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The Indian Vacuum Society (IVS) was established in 1970 to promote vacuum science and technology in academic, industrial and R&D institutions in India. IVS is a member society of the International Union for Vacuum Science, Technique and Applications (IUVSTA). It has organized International and national symposia, short term courses and workshops on different aspects of Vacuum Science and Technology at regular intervals. So far 27 National symposia, 4 International Symposia and 47 courses have been organized at various locations in India. There has been an active participation from R&D establishments, universities and Indian industries during all these events.

In view of the current global situation and emerging trends in vacuum technology, the executive committee of the IVS suggested to us that we organize an International Symposium at the Variable Energy Cyclotron Centre, Kolkata from 15–17 February 2012. At the Variable Energy Cyclotron Centre we have a large number of high vacuum systems used in the K130 Cyclotron and K500 Superconducting Cyclotron. Also a large cryogenic system using LHe plant is in operation for cryopanels and a superconducting magnet for K-500 Cyclotron. The main areas covered at the symposium were the production and measurement of vacuums, leak detection, design and development of large vacuum systems, vacuum metallurgy, vacuum materials and the application of high vacuums in cyclotrons, LINACS and other accelerators. This symposium provided an opportunity for interaction between active researchers and technologists and allowed them to review the current situation, report recent experimental results, share the available expertise and consider the future R&D efforts needed in this area.

Keeping the industrial significance of vacuum technology in mind, an exhibition of the vacuum related equipment, accessories, products etc by various suppliers and manufactures was organized alongside the symposium. Participation by a large number of exhibitors clearly indicates that industry has advanced quite significantly. During the symposium, the Indian Vacuum Society honoured two distinguished personalities for their remarkable and significant contributions to the field of vacuum science and development of technology in the country. Awards were presented for both oral and poster papers during the symposium. A committee evaluated the scientific content and clarity of presentation of contributed papers. We believe that deliberations and discussions at the symposium will help gain a better understanding of the complicated and involved technology of vacuum science and be of benefit to scientists and technologists.

Subimal Saha Convener Gautam Pal Co-Convener V S Pandit Secretary Surajit Pal Treasurer

Indian Vacuum Society

The Indian Vacuum Society (IVS) was established in 1970. It has over 900 members including many from Industry and R&D Institutions spread over the country. The society has an active chapter at Kolkata. The society was formed with the main aim to promote, encourage and develop the growth of Vacuum Science, Techniques and Applications in the country. In order to achieve this aim it has been conducting a number of short term courses at graduate and technician levels on vacuum science and technology on topics ranging from low vacuum to ultrahigh vacuum. So far it has conducted 47 such courses in different parts of the country and imparted training to more than 1500 people in the field. Some of these courses were in-plant training courses conducted on the premises of the establishment and designed to take care of the special needs of the establishment. Recently such a course was conducted at the Nuclear Fuel Complex, Hyderabad and Fundamentals of Vacuum Technology in general and Large Vacuum Furnaces, Vacuum Metallurgy in particular were the themes of the workshop. IVS also regularly conducts national and international seminars and symposia on vacuum science and technology with special emphasis on themes related to applications of vacuum. A large number of delegates from all over India take part in the deliberations of such seminars and symposia and present their work. IVS also arranges technical visits to different industries and research institutes. The society also helped in the UNESCO sponsored post-graduate level courses in vacuum science, technology and applications conducted by Mumbai University. IVS extended its support in standardizing many of the vacuum instruments and played a vital role in helping to set up a Regional Testing Centre along with BARC. As part of the development of vacuum education, the society arranges the participation of expert members on the subject to deliver lectures and take part in devising courses in the universities.

IVS has published the 'Bulletin of Indian Vacuum Society' quarterly since its inception, in which articles on Vacuum and related topics are published. NIRVAT, news, announcements, and reports are the other features of the Bulletin. The articles in the Bulletin are internationally abstracted. The Bulletin is distributed free to all members of the society. The society also publishes the proceedings of National, International Symposia/Seminars, manuals, lecture notes etc. It has published 'Vacuum Directory' containing very useful information on vacuum technology and it is in the process of updating this. The IVS has also set up its own website (http://www.ivsnet.org) in January 2002. The website contains information about IVS, lists of EC members, events and news, abstracts of articles published in the Bulletin of Indian Vacuum Society, utilities, technical data, announcements, reports, membership and other forms including advertisements. Our Society is a member society of the International Union of Vacuum Science, Techniques and Applications (IUVSTA) and many IVS members are nominated in its various committees since 1970. In 1983, IVS conducted an International Symposium on Vacuum Technology and Nuclear Applications in BARC, Mumbai under the sponsorship of IUVSTA. In 1987, IVS arranged, the Triennial International Conference on Thin Films in New Delhi, where more than 200 foreign delegates participated. IVS also hosted the IUVSTA Executive Council Meeting along with the conference. The society organized yet again an International Conference on Vacuum Science and Technology (IVS-2007) during 28-30 November 2007 at TIFR, Colaba Camups, Mumbai.

IVS organizes the prestigious Professor Balakrishnan Memorial Lecture in memory of its founder vice-president. Leading scientists in the field from India and abroad are invited to deliver the talk. So far 24 lectures have been held in this series. IVS has instituted the 'IVS- Professor D Y Phadke Memorial Prize' in memory of our founder President the late Professor D Y Phadke in the University of Mumbai. The prize is given every year to the top ranker in the MSc (Physics) examination conducted by the Mumbai University. IVS Kolkata Chapter has established the Dr A S Divatia Memorial Trust with the objective to organize the Dr A S Divatia Memorial Lecture and a seminar once a year and to set up a vacuum testing and calibration facility. IVS has instituted an award in memory of late Shri C. Ambasankaran, its past president and pioneer of vacuum technology in India. This award is given to one of the best papers presented in the national symposium conducted by IVS. One more best Poster award 'Smt Shakuntalabai Vyawahare Memorial Prize' is established from the donation given by Shri. Mohan R. Vyawahare, a life member, in memory of his mother.

Recently, The IVS has decided to offer financial support to cover travel, registration fees and accommodation charges for a few selected students and participants (preferably IVS life members) for attending conferences in the country.

Shrikrishna Gupta Gen. Secretary, IVS

All papers published in this volume of Journal of Physics: Conference Series have been peer reviewed through processes administered by the proceedings Editors. Reviews were conducted by expert referees to the professional and scientific standards expected of a proceedings journal published by IOP Publishing.

Variable Energy Cyclotron Centre (VECC) has two large cyclotrons, K-130 cyclotron and K-500 cyclotron. The first beam in the room temperature K-130 cyclotron (RTC) was accelerated in June 1977. The cyclotron accelerated and delivered alpha and proton beams consistently to the cyclotron users for several years. Heavy ion beams were available in this cyclotron from 1997 to 2007. Presently, the cyclotron is working as a primary source for RIB production. The cyclotron has an acceleration chamber volume of about 28 m³. The total length of beam line is about 65 m. Vacuum of the order of 1 x 10⁻⁶ mbar is presently maintained in the cyclotron and beam line using diffusion pumps. It is one of the largest vacuum systems operating in India. It is consistently being operated 24 x 7 round the year giving beam to the cyclotron users. A K-500 superconducting cyclotron (SCC) with K=520 has been constructed at Kolkata. SCC will be used to accelerate beams to 80 MeV/A for light heavy ions and about 10 MeV/A for medium mass heavy ions. Three turbo molecular pumps are connected to the acceleration chamber. Three cryopanels placed inside the lower dees in the valley gap of the superconducting magnet are available in the accelerating chamber for achieving high vacuum. The acceleration chamber having a volume of about 1.0 m³ was operated using turbomolecular pumps, liquid nitrogen cooled panels and liquid helium cooled cryopanels at different stages during beam commissioning. Differential pumping is provided across the RF liner to avoid distortion. The first beam line of about 21 m has been installed in the cyclotron. The outer vacuum chamber of the cyclotron magnet cryostat has active pumping. The vacuum system of the superconducting cyclotron is also operating reliably round the clock throughout the year. The paper describes the details of the vacuum systems of the large cyclotrons at VEC Centre Kolkata India, its commissioning and operating experience.

Vacuum technology is an integral part of any accelerator system. At IUAC we have a 15UD PELLETRON, superconduting LINAC, Low Energy Ion beam Facility and a 1.7MV pelletron. Vacuum requirement in these accelerators is ~10⁻⁸ torr. Various types of Vacuum pump are used in different zones of the accelerators depending on load. Since the whole accelerator is quite long, distributed pumps are placed in different sections as per load. In ion sources displacement type pump viz turbo-pumps are usually used as the gas load is quite high. In other parts of the accelerator combination of getter and ion pumps are used. It is very much necessary to isolate different sections for maintenance purpose. Proper valves are used to isolate the sections and to avoid vacuum accidents proper interlock system is introduced. If air goes in some sections accidentally, valves will close automatically to protect other sections. The talk will cover different types of pumps and interlock used in accelerators at IUAC.

High pulsed power magnetrons and klystrons for medical and industrial accelerators, and high CW power klystrons and gyrotrons for plasma heating in tokamak, are being developed at CEERI. S-band 2.0MW pulsed tunable magnetrons of centre frequency 2856MHz and 2998 MHz were developed, and S-band 2.6MW pulsed tunable magnetron is being developed for medical LINAC, and 3MW pulsed tunable magnetron is being developed for industrial accelerator. S-band (2856MHz), 5MW pulsed klystron was developed for particle accelerator, and S-band 6MW pulsed klystron is under development for 10MeV industrial accelerator. 350MHz, 100kW (CW) klystron is being developed for proton accelerator, and C-band 250kW (CW) klystron is being developed for plasma heating. 42GHz, 200kW (CW/Long pulse) gyrotron is under development for plasma heating. Plasma filled tubes are also being developed for switching. 25kV/1kA and 40kV/3kA thyratrons were developed for high voltage high current switching in pulse modulators for magnetrons and klystrons. 25kV/3kA Pseudospark switch of current rise time of 1kA/|a-sec and pulse repetition rate of 500Hz is being developed. Plasma assisted high power microwave device is also being investigated.

A low energy heavy ion irradiation/implantation facility has been developed at VECC, Kolkata for materials science and atomic physics research, utilizing indigenously developed 6.4 GHz ECR ion source. The facility provides high charge state ion beams of N, O, Ne, Ar, S, Kr, Xe, Fe, Ti, Hf etc. up to a few micro amperes to an energy of 10 keV per charge state.The beam energy can be further enhanced by floating the target at a negative potential (up to 25 kV). The ion beam is focused to a spot of about 2 mm diameter on the target using a set of glaser lenses. A x-y scanner is used to scan the beam over a target area of 10 mm x 10 mm to obtain uniform implantation. The recently commissioned multi facility sample chamber has provision for mounting multiple samples on indigenously developed disposable beam viewers for insitu beam viewing during implantation. The ionization chamber of ECR source is mainly pumped by ECR plasma. An additional pumping speed has been provided through extraction hole and pumping slots to obtain low base pressure. In the ion source, base pressure of 1x10⁻⁷ Torr in injector stage and ~5x10⁻⁸ Torr in extraction chamber have been routinely obtained. The ultra-high vacuum multi facility experimental chamber is generally kept at ~ 1x10⁻⁷ Torr during implantation on the targets. This facility is a unique tool for studying fundamental and technologically important problems of materials science and atomic physics research. High ion flux available from this machine is suitable for generating high defect densities i.e. high value of displacement-per-atom (dpa). Recently this facility has been used for studies like "Tunability of dielectric constant of conducting polymer Polyaniline (PANI) by low energy Ar⁹⁺ irradiation" and "Fe¹⁰⁺ implantation in ZnO for synthesis of dilute magnetic semiconductor".

Energetic electrons and intense bremsstrahlung radiation from 8 MeV Microtron are being utilized in variety of collaborative research programs in radiation physics and allied sciences involving premier institutions of the country and sister universities of the region. The first of its kind electron accelerator in the country, set up at Mangalore University in collaboration with RRCAT Indore and BARC Mumbai, has been facilitating researchers since its inception with its inherent simplicity, ease of construction, low cost and excellent beam quality. A bird's eye view on the reliable aspects of the machine, efforts behind the continuous operation of the accelerator and important applications of the accelerator in physical and biological sciences are presented in this paper.

UHV/XHV users are increasingly demanding vacuum pumps with high performances with smaller package and weight. This requires a more efficient combination/integration of the currently available pumping technologies and, possibly, the development of new approaches in vacuum pumping systems. Non Evaporable Getter (NEG) pumps represent one of the most appealing option to UHV/XHV pumping, thanks to his large pumping speed and sorption capacity for several active gases (H₂, H₂O, CO, O₂, N₂, ...). NEG pumps can also reduce the pump down and bake-out time and can keep a stable pressure level in UHV conditions even if the other pumping systems are switched off. However, NEG pumps are unable to sorb, in UHV/XHV systems, the small amount of noble gases and methane which, on the other hand, can be removed by sputter ion pump (SIP). For this reason, extensive studies have been carried out to combine NEG and SIP technologies. Some results of the vacuum characterization of such combination are discussed in this work and compared with traditional pumping approaches based on large SIP. A further step forward is the NEXTorr^®3 pump which is an integration of a NEG pump (pumping speed ranging between 100 to 500 l/s for hydrogen) with a SIP (pumping speed of 6 and 10 l/s for Ar and CH₄ respectively) into a single small package unit. Examples of applications of this new approach in vacuum technology will be given to demonstrate the simplification of the design and operation of UHV/XHV systems.

The present work reports on progress in the design of modular UHV cluster tool multichamber systems. A wide range of processes has been implemented in the Deposition Process Chambers (DPC's), including rf-PECVD, vhf-PECVD, ECR-PECVD and HWCVD. A wide range of intrinsic and doped amorphous and microcrystalline silicon and silicon alloy materials have been produced and have been used in the fabrication of several types of electronic devices such as solar cells, Light Emitting Devices (LED's), Thin Film Transistors (TFT's), etc. using multichamber systems at several laboratories worldwide.

In a thermo vacuum chamber, attaining and controlling low and high temperatures (-100 Deg. C to +120 Deg. C) is a very important task. This paper describes the development of "Open loop, auto reversing liquid nitrogen based thermal system". System specifications, features, open loop auto reversing system, liquid nitrogen flow paths etc. are discussed in this paper. This thermal system consists of solenoid operated cryogenic valves, double embossed thermal plate (shroud), heating elements, temperature sensors and PLC. Bulky items like blowers, heating chambers, liquid nitrogen injection chambers, huge pipe lines and valves were not used. This entire thermal system is very simple to operate and PLC based, fully auto system with auto tuned to given set temperatures. This system requires a very nominal amount of liquid nitrogen (approx. 80 liters / hour) while conducting thermo vacuum tests. This system was integrated to 1.2m dia thermo vacuum chamber, as a part of its augmentation, to conduct extreme temperature cycling tests on passive antenna reflectors of satellites.

Hydrogen gas is generated by electrolysis method in a compact hydrogen generator. A simple procedure reduces handling and storage of hydrogen cylinders for laboratory applications. In such a system, we are producing deuterium gas from heavy water by electrolysis method. After production of the deuterium gas, we have checked the purity level of the outgoing deuterium from the electrolyser. The test was carried out in a high vacuum system in which one residual gas analyser (RGA) was mounted. The deuterium gas was inserted by one manual gas leak valve in to the vacuum system. In this study, the effect of the emission current of the RGA on the detection of the deuterium was performed. In this paper, we will discuss the detail analysis of the deuterium gas and the effect of the emission current on the partial pressure measurement.

BARC is developing a technology for the accelerator driven subcritical system (ADSS) that will be mainly utilized for the transmutation of nuclear waste and enrichment of U233. Design and prototyping of a superconducting medium velocity cavity has been taken up as a part of the ADSS project. The cavity design for β = 0.49, f = 1050 MHz has been optimized to minimize the peak electric and magnetic fields, with a goal of 5 MV/m of accelerating gradient at a Q > 5×10⁹ at 2 K. After the design optimization one single cell cavity was fabricated from large grain (RRR>99) Niobium material. This report presents the design, fabrication, electron beam welding and RF measurements at room temperature before and after electron beam welding.

Multipurpose vacuum processing systems are cost effective; occupy less space, multiple functional under one roof and user friendly. A multipurpose vacuum induction system was designed, fabricated and installed in a record time of 6 months time at NFTDC Hyderabad. It was designed to function as a) vacuum induction melting/refining of oxygen free electronic copper/pure metals, b) vacuum induction melting furnace for ferrous materials c) vacuum induction melting for non ferrous materials d) large vacuum heat treatment chamber by resistance heating (by detachable coil and hot zone) e) bottom discharge vacuum induction melting system for non ferrous materials f) Induction heat treatment system and g) directional solidification /investment casting. It contains provision for future capacity addition. The attachments require to manufacture multiple shaped castings and continuous rod casting can be added whenever need arises. Present capacity is decided on the requirement for 10years of development path; presently it has 1.2 ton liquid copper handling capacity. It is equipped with provision for capacity addition up to 2 ton liquid copper handling capacity in future. Provision is made to carry out the capacity addition in easy steps quickly. For easy operational maintenance and troubleshooting, design was made in easily detachable sections. High vacuum system is also is detachable, independent and easily movable which is first of its kind in the country. Detailed design parameters, advantages and development history are presented in this paper.

In the Aditya Tokamak, one of primary requirement for plasma generation is to feed the required quantity of the fuel gas prior to plasma shot. Gas feed system mainly consists of piezoelectric gas leak valve and gas reservoir. The Hydrogen gas is prior to 300ms loop voltage for the duration of 4 msec to 7 msec. Gas is puffed during the shot for required plasma parameters and to increase plasma density using the same system. The valve is controlled by either continuous voltage or pulses of different width, amplitude and delay with respect to loop voltage. These voltage pulses are normally applied through standard pulse generator. The standard pulse generator is replaced by micro controller based in housed developed programmable pulse generator system consists of in built power supply, BNC input for external trigger, BNC output and serial interface. This programmable pulse generator is successfully tested and is in operation for gas puffing during ADITYA Tokamak experiments. The paper discusses the design and development aspect of the system.

National Physical Laboratory, the National Metrology Institute (NMI) of India is maintaining Primary standards of pressure that cover several decades of pressure, starting from 3.0E-06 Pa to 1.0 GPa. Among which a recent addition is a Force Balanced Piston Gauge, the non-rotating piston type, having better resolution and zero stability compared to any other primary pressure standards commercially available in the range 1.0 Pa to 15.0 kPa (abs and gauge). The characterization of this FPG is done against Ultrasonic Interferometer Manometer (UIM), the National Primary pressure standard, working in the range 1.0 Pa to 130.0 kPa (abs and diff) and Air Piston Gauge (APG), a Transfer Pressure Standard, working in the range 6.5 kPa to 360 kPa (abs and gauge), in their overlapping pressure regions covering both absolute and gauge pressures. As NPL being one of the signatories to the CIPM MRA, the Calibration and Measurement Capabilities (CMC) of both the reference standards (UIM & APG), are Peer reviewed and notified in the Key Comparison Data Base (KCDB) of BIPM. The estimated mean effective area of the Piston Cylinder assembly of this FPG against UIM (980.457 mm²) and APG (980.463 mm²) are well within 4 ppm and 10 ppm agreement respectively, with the manufacturer's reported value (980.453 mm²). The expanded uncertainty of this FPG, Q(0.012 Pa, 0.0025% of reading), evaluated against UIM as reference standard, is well within the reported value of the manufacturer, Q(0.008 Pa, 0.003% of reading) at k = 2. The results of the characterization along with experimental setup & measurement conditions (for gauge and absolute pressure measurements), uncertainty budget preparation and evaluation of measurement uncertainty are discussed in detail in this paper.

A vacuum chamber, to house the optical pulse compressor of a 150 TW Ti:sapphire laser system, has been designed, fabricated, and tested. As the intensity of the laser pulse becomes very high after pulse compression, there is phase distortion of the laser beam in air. Hence, the beam (after pulse compression) has to be transported in vacuum to avoid this distortion, which affects the laser beam focusability. A breadboard with optical gratings and reflective optics for compression of the optical pulse has to be kept inside the chamber. The chamber is made of SS 316L material in cuboidal shape with inside dimensions 1370×1030×650 mm³, with rectangular and circular demountable ports for entry and exit of the laser beam, evacuation, system cables, and ports to access optics mounted inside the chamber. The front and back sides of the chamber are kept demountable in order to insert the breadboard with optical components mounted on it. Leak tightness of 9×10⁻⁹ mbar-lit/sec in all the joints and ultimate vacuum of 6.5×10⁻⁶ mbar was achieved in the chamber using a turbo molecular pumping system. The paper describe details of the design/ features of the chamber, important procedure involved in machining, fabrication, processing and final testing.

Fabrication of superconducting cavities has been taken up as a part of the development of accelerator driven sub critical system (ADSS) by Bhabha Atomic Research Centre. Large grain (RRR>99) pure niobium was chosen as the material for the cavity. Niobium,for its application as superconductor requires extremely high quality joints, feasible only by electron beam welding at high vacuum environment. An indigenously developed 100kV, 4kW high vacuum electron beam welding machine has been utilized to carry out the welding operations. Planning of the weld sequences was chalked out. Holding fixtures for the cavity, consists of seven numbers of joints have been fabricated beforehand. A few coupons were welded for optimization of the weld parameters and for inspection of the weld purity by indigenously developed secondary ion mass spectroscopy. The report describes the welding equipment and the stage wise joining operations of the cavity in details and also discusses the qualification testing of the welded cavity.

Electron beam assisted physical vapour deposition (EB-PVD) and purification of metal by repeated melting using electron guns is a well-established technique in industrial metallurgy. Strip electron gun is considered a cost effective alternative to multiple pencil guns for handling of large size substrates. In the electron guns, the thermionic emission of the electrons from a filament is achieved by using AC or DC filament heating. A study of their relative merits and demerits was conducted for the both types of electron guns. Due to finite length of the filament, the magnetic field generated around the filament by heating current drops down towards ends. The DC filament heating results in electron beam with a comet shape having high power density hot spot at one end with low power density tails. With AC filament heating, electron beam oscillates with the frequency as that of heating current. The study of vapour flux distribution using DC gun revealed that highly directional vapour evolution takes place from a smaller hot spot whereas with AC gun vapour evolution occurs from an oscillatory 2D-evaporating source. The vapour deposit on substrate indicated that evaporation using DC gun caused splashing and granular deposit due to volumetric melting and evaporation from the ingot. This is contrary to the AC filament heating wherein quiet evaporation was observed due to surface melting and evaporation. The experimental results are critically reviewed to decide the configuration of electron guns for large-scale evaporation.

VEC K500 superconducting cyclotron will be used to accelerate heavy ion. The accelerated beam will be transported to different beam halls by using large switching magnets. The vacuum chamber for the switching magnet is around 1000 mm long. It has a height of 85 mm and width varying from 100 mm to 360 mm. The material for the chamber has been chosen as SS304.The material for the vacuum chamber for the switching magnet has been chosen as SS304. Design of the vessel was done as per ASME Boiler and Pressure Vessel Code, Section VIII, Division 1. It was observed that primary stress values exceed the allowable limit. Since, the magnet was already designed with a fixed pole gap; increase of the vacuum chamber plate thickness restricts the space for beam transport. Design was optimized using stress analysis software ANSYS. Analysis was started using plate thickness of 4 mm. The stress was found higher than the allowable level. The analysis was repeated by increasing plate thickness to 6 mm, resulting in the reduction of stress level below the allowable level. In order to reduce the stress concentration due to sharp bend, chamfering was done at the corner, where the stress level was higher. The thickness of the plate at the corner was increased from 6 mm to 10 mm. These measures resulted in reduction of localized stress.

In state of art technology, integrated devices are widely used or their potential advantages. Common system reduces weight as well as total space covered by its various parts. In the state of art surveillance system integrated SWIR and night vision system used for more accurate identification of object. In this system a common optical window is used, which passes the radiation of both the regions, further both the spectral regions are separated in two channels. ZnS is a good choice for a common window, as it transmit both the region of interest, night vision (650 – 850 nm) as well as SWIR (0.9 – 1.7 μm). In this work a broad band anti reflection coating is developed on ZnS window to enhance the transmission. This seven layer coating is designed using flip flop design method. After getting the final design, some minor refinement is done, using simplex method. SiO₂ and TiO₂ coating material combination is used for this work. The coating is fabricated by physical vapour deposition process and the materials were evaporated by electron beam gun. Average transmission of both side coated substrate from 660 to 1700 nm is 95%. This coating also acts as contrast enhancement filter for night vision devices, as it reflect the region of 590 – 660 nm. Several trials have been conducted to check the coating repeatability, and it is observed that transmission variation in different trials is not very much and it is under the tolerance limit. The coating also passes environmental test for stability.

The paper describes an experimental study aimed at standardizing brazing procedure for joining Glidcop to OFE Cu for its application in upgraded photon absorbers of 2.5 GeV synchrotron radiation source, Indus-2. Two different brazing routes, involving brazing with silver base (BVAg-8) and gold base (50Au/50Cu) alloys, were studied to join Glidcop to OFE Cu. Brazing with both alloys yielded helium leak tight and bakeable joints with acceptable shear strengths.

Sheet beam transport through closed periodic cusped magnet has been analysed. On the basis of analysis, closed PCM is designed to transport elliptical sheet beam of size 30 mm (width)×1.2 mm (thickness), beam voltage 120 kV, current density 600 A/cm². This beam is selected for 30 GHz high power sheet beam klystron which has potential application for high gradient LINAC. Selection of aspect ratio of magnetic tunnel and magnetic period is the critical aspect. When aspect ratio of magnetic period is 4:1 and magnetic period is 10 mm, horizontal magnetic force profile matches nearly with horizontal space charge field profile. However, to get desired peak value of magnetic field is very critical. When magnetic period is 10 mm, cross-sectional size of magnetic tunnel is 42.4 mm (width) ×10.6 mm (height), axial thickness of each magnets is 4.2 mm, transverse thickness is 20 mm, the simulated value of magnetic field is 720 G. Above sheet beam with current density 100 A/cm² transports up to 120 mm distance through this magnetic tunnel without any instability.

In view of up-gradation of K-130 Cyclotron at VECC, Kolkata, we have designed a new Vacuum chamber to modify the existing vacuum chamber system. This new chamber is meant for C-shaped 1T dipole type 159.5° Analysing Magnet of 4710 OD × 2750 ID × 1075 mm tall in the RIB feeder beam-line. The welded type vacuum chamber is made of SS-304. The chamber with trapezoidal cross-section is of 4447 OD × 4057 ID × 61.5 mm average height. Pumping ports and modules are selected accordingly to ensure the required high vacuum for beam transport. The chamber improves the base vacuum and reduces the complicated O-ring replacement mandatory for existing chamber made of aluminium alloy. The new chamber is installed at site along with all the pumping module and beam line components. This paper presents the detailed design, installation and commissioning results.

Titanium sublimation pumps (TSP) provide inexpensive large pumping speeds for active gases especially in UHV environment where residual gases are mainly H₂ and CO etc. The pumping speed of TSP is independent of pressure in this range. Sublimation of Ti on liquid nitrogen (LN₂) cooled surfaces is expected to provide large porosity in deposited film and this may also result in further enhancement of its pumping speed. Accordingly a liquid nitrogen cooled TSP was developed to achieve clean vacuum in 10⁻¹¹ mbar range in combination of sputter ion pump which is mainly used to take care of inert gas load. The LN₂ shroud was designed to have 1.9 litre capacity and offered approximately 2000 cm² cooled surface area with approximately 250cm² area coated with titanium film. This paper describes the performance of the TSP at room temperature as well as after cooling with LN₂. Quadrupole mass analyzer was utilized to analyze residual gases. Simultaneously for pumping speed measurements for different gasses, a setup with known conductance was also appended.

Deposition of NEG thin films onto the interior walls of the vacuum chambers is an advanced technique to convert a vacuum chamber from a gas source to an effective pump. These films offer considerably large pumping speed for reactive gases like CO, H₂ etc. A UHV compatible pumping speed measurement system was developed in-house to measure the pumping speed of NEG coated chambers. To inject the fixed quantity of CO and H₂ gas in pumping speed measurement set-up a calibrated leak was also developed. Stainless steel chambers were sputter coated with thin film of Ti-Zr-V getter material using varied parameters for different compositions and thickness. Pumping capacity which is a function of sorbed gas quantities was also studied at various activation temperatures. In order to optimize the activation temperature for maximum pumping speed for CO and H₂, pumping speeds were measured at room temperature after activation at different temperatures. The experimental system detail, pumping performance of the NEG film at various activation temperatures and RGA analysis are presented.

Helium leak testing is the most versatile form of weld qualification test for any vacuum application. Almost every ultra-high vacuum (UHV) system utilizes this technique for insuring leak tightness for the weld joints as well as demountable joints. During UHV system under operational condition with many other integrated components, in-situ developed leaks identification becomes one of the prime aspect for maintaining the health of such system and for continuing the experiments onwards. Since online utilization of leak detector (LD) has many practical limitations, residual gas analyser (RGA) can be used as a potential instrument for online leak detection. For this purpose, a co-relation for a given leak rate between Leak Detector and RGA is experimentally established. This paper describes the experimental aspect and the relationship between leak detector and RGA.

Commonly used materials for accelerator components are those which are vacuum compatible and thermally conductive. Stainless steel, aluminum and copper are common among them. Stainless steel is a poor heat conductor and not very common in use where good thermal conductivity is required. Aluminum and copper and their alloys meet the above requirements and are frequently used for the above purpose. The accelerator components made of aluminum and its alloys using welding process have become a common practice now a days. It is mandatory to use copper and its other grades in RF devices required for accelerators. Beam line and Front End components of the accelerators are fabricated from stainless steel and OFHC copper. Fabrication of components made of copper using welding process is very difficult and in most of the cases it is impossible. Fabrication and joining in such cases is possible using brazing process especially under vacuum and inert gas atmosphere. Several accelerator components have been vacuum brazed for Indus projects at Raja Ramanna Centre for Advanced Technology (RRCAT), Indore using vacuum brazing facility available at RRCAT, Indore. This paper presents details regarding development of the above mentioned high value and strategic components/assemblies. It will include basics required for vacuum brazing, details of vacuum brazing facility, joint design, fixturing of the jobs, selection of filler alloys, optimization of brazing parameters so as to obtain high quality brazed joints, brief description of vacuum brazed accelerator components etc.

SST-1 Tokamak is a steady state super-conducting tokamak for plasma discharge of 1000 sec duration. The plasma discharge of such long time duration can be obtained by reducing the impurities level, which will be possible only when SST-1 vacuum chamber is pumped to ultra high vacuum. In order to achieve UHV inside the chamber, the baking of complete vacuum chamber has to be carried out during pumping. For this purpose the C-channels are welded inside the vacuum vessel. During baking of vacuum vessel, these welded channels should be helium leak tight. Further, these U-channels will be in accessible under operational condition of SST-1. So, it will not possible to repair if any leak is developed during experiment. To avoid such circumstances, a dedicated high vacuum chamber is used for baking of the individual vacuum modules and sectors before assembly so that any fault during welding of the channels will be obtained and repaired. This paper represents the baking of vacuum vessel modules and sectors and their temperature distribution along the entire surface before assembly.

The Steady-state Superconducting Tokamak (SST-1) is an indigenously built medium sized fusion device at IPR designed for plasma duration of 1000 seconds. It consists of two large vacuum chambers – Vacuum Vessel (16 m³) and Cryostat (39 m³) which will be pumped to UHV and HV pressures respectively using a set of turbo molecular pumps, Cryo-pumps and Roots pumps. The total as well as the partial pressure measurement in these chambers will be carried out using a set of Pirani gauges, Bayard Alpert type gauges, Capacitance manometers and Residual Gas Analyzers (RGA). A reliable and accurate pressure measurement is essential for successful operation of SST-1 machine. For this purpose a gauge calibration system is set up in SST-1 Vacuum laboratory based on Spinning Rotor Gauge which can measure absolute pressure in the range 1.0 mbar to 1.0 × 10⁻⁷ mbar. This system is designed to calibrate up to five gauges simultaneously for different gases in different operating pressure ranges of the gauges. This paper discusses the experimental set-up and the procedure adopted for the calibration of such vacuum gauges.

In ultra high vacuum (UHV) range, hydrogen is a dominant residual gas in vacuum chamber. Hydrogen, being light gas, pumping of hydrogen in this vacuum range is limited with widely used UHV pumps, viz. turbo molecular pump and cryogenic pump. Pre condensed argon layers in cryogenic pump create porous structure on the surface of the pump, which traps hydrogen gas at a temperature less than 20° K. Additional argon gas injection in the cryogenic pump, at lowest temperature, generates multiple layers of condensed argon as a porous frost with 10 to 100 A° diameters pores, which increase the pumping capacity of hydrogen gas. This pumping mechanism of hydrogen is more effective, to pump more hydrogen gas in UHV range applicable in accelerator, space simulation etc. and where hydrogen is used as fuel gas like tokamak. For this experiment, the cryogenic pump with a closed loop refrigerator using helium gas is used to produce the minimum cryogenic temperature as ~ 14° K. In this paper, effect of cryosorption of hydrogen is presented with different levels of argon gas and hydrogen gas in cryogenic pump chamber.

SST-1 Tokamak is under commissioning at Institute for Plasma Research in mission mode. It comprises of a toroidal doughnut shaped plasma chamber, surrounded by liquid helium cooled superconducting magnets and LN₂ thermal shields, housed inside the cryostat chamber. The superconducting magnet system of SST-1 consists of toroidal field (TF) magnets and poloidal field (PF) magnets and will be operated at internal supercritical helium pressure of 4.5 bar (a) under very low temperature of 4.5 K and carrying a DC current of 10 kA. High-vacuum compatibility up to low-pressure ≤ 1 × 10⁻⁵ mbar is one of the most essential features of these superconducting magnets in order to avoid the heat losses due to conduction and convection. This paper describes the extensive tests carried out under representative conditions to ensure the high-vacuum compatibility of the SST-1 magnets before assembly to the main system.

Vacuum system of steady-state Superconducting Tokamak (SST-1) has a very essential role during SST-1 plasma operation. For this purpose, its data acquisition and control system should be reliable and accurate. The PXI based faster real time data acquisition and control system were used for performing various operations like online data measurements, control, display, status indication in form of graphical visualization and storing the data for future analysis. We developed such PXI based vacuum control and implemented to our ongoing experimental set-up. This paper will describe the detailed information and guidance on PXI based platform for data acquisition and control used during the campaign.

Zirconium oxide (ZrO₂) thin films were deposited on to p – Si and quartz substrates by sputtering of zirconium target at an oxygen partial pressure of 4x10⁻² Pa and sputter pressure of 0.4 Pa by using DC reactive magnetron sputtering technique. The effect of annealing temperature on structural, optical, electrical and dielectric properties of the ZrO₂ films was systematically studied. The as-deposited films were mixed phases of monoclinic and orthorhombic ZrO₂. As the annealing temperature increased to 1073 K, the films were transformed in to single phase orthorhombic ZrO₂. Fourier transform infrared studies conform the presence of interfacial layer between Si and ZrO₂. The optical band gap and refractive index of the as-deposited films were 5.82 eV and 1.81. As the annealing temperature increased to 1073 K the optical band gap and refractive index increased to 5.92 eV and 2.10 respectively. The structural changes were influenced the capacitance-voltage and current-voltage characteristics of Al/ZrO₂/p-Si capacitors. The dielectric constant was increased from 11.6 to 24.5 and the leakage current was decreased from 1.65×10⁻⁷ to 3.30×10⁻⁹ A/ cm² for the as-deposited and annealed at 1073 K respectively.

Zinc Aluminum Oxide(ZAO) thin films were deposited on glass substrates by DC reactive magnetron sputtering in an Ar+O₂ gas mixture using commercial available Zn metal (99.99% purity) and Al (99.99% purity) targets of 2 inch diameter and 4 mm thickness. The films were characterized and the effect of aluminum (Al) concentration (2 at %-6 at %) on the structural and optical properties was studied. The average crystallite size obtained from Scherer formula is in the range of 32-44nm. Microstructural analysis using Scanning Electron Microscope (SEM) supplemented with EDS is carried out to find the grain size as well as to find the composition elemental data of prepared thin films. Optical study is performed to calculate the extinction coefficient (k), absorption coefficient (a), optical band gap (E_g) using transmission spectra obtained using UV-VIS-NIR spectrophotometer. There was widening of optical band gap with increasing aluminum concentration. ZAO film with low resistivity 3.2 × 10⁻⁴ cm and high transmittance of 80% is obtained for 3at% doped Al which is crucial for optoelectronic applications.

For the generation of microwaves, Electron beam devices operating in vacuum are most widely used. For pulsed and high power microwave generation, Virtual cathode oscillators (VIRCATORs) are said to be simple in operation and construction. They are generally driven by a pulsed power source which gives high input powers to the Vircator connected as load. Vircator, depending upon its efficiency, converts the electrical input power to the microwave power. We are presenting the results of an axial Vircator operating in 2×10⁻⁴ mbar vacuum and is driven by a compact pulsed power source. The energy source and pulse compression is realized in very user friendly approach to run the system. The radiating system presently runs at relatively low powers but has the scope of reaching to high power by a logical improvement. A study of effect of collapsing diode impedance, of the vacuum field emission diode of the Vircator, on the microwave emission is presented in the paper. We are also presenting the microwave emission measurement conducted in the given system. Effect of vacuum is also studied to the extent of present experimental limits.

SST-1 Tokamak, a steady state super-conducting device, is under refurbishment to demonstrate the plasma discharge for the duration of 1000 second. The major fabricated components of SST-1 like vacuum vessel, thermal shields, superconducting magnets etc have to be tested for their functional parameters. During machine operation, vacuum vessel will be baked at 150 °C, thermal shields will be operated at 85 K and magnet system will be operated at 4.5 K. All these components must have helium leak tightness under these conditions so far as the machine operation is concerned. In order to validate the helium leak tightness of these components, in-house high vacuum chamber is fabricated. This paper describes the analysis, design and fabrication of high vacuum chamber to demonstrate these functionalities. Also some results will be presented.

A compact 180 kV electron beam system is designed for high power microwave generation. The electron beam system is consists of a secondary energy storage device, which can deliver energy to the load at faster rate than usual primary energy storage system such as tesla transformers or marx generator. The short duration, high voltage pulse with fast rise time and good flattop is applied to vacuum diode for high power microwave generation. The compact electron beam system is made up of single turn primary tesla transformer which charges a helical pulse forming line and transfers its energy to vacuum diode through a high voltage pressurized spark gap switch. We have used helical pulse forming line which has higher inductance as compared to coaxial pulse forming line, which in turns increases, the pulse width and reduce the length of the pulse forming line. Water dielectric medium is used because of its high dielectric constant, high dielectric strength and efficient energy storage capability. The time dependent breakdown property and high relative permittivity of water makes it an ideal choice for this system. The high voltage flat-top pulse of 90 kV, 260 ns is measured across the matched load. In this article we have reported the design details, simulation and initial experimental results of 180 kV pulsed electron beam system for high power microwave generation.

SST-1 tokamak is a long pulse tokamak designed for the plasma operation up to 1000 sec duration. Gas feed system and gas exhaust management will play a very crucial role during plasma discharge. During the different type of operations of tokamak like wall conditioning, diverter operation and neutral beam injection, a large amount of gas will be fed into the vacuum chamber at different locations. Also during plasma operations, the gas will be fed both in continues and pulse mode. Gas feed will be carried out mainly using piezo-electric valves controlled by PXI based data acquisition and control system. Such operations will lead to a huge amount gas exhaust by the main system which requires good exhaust facility to searches, great care should be taken in constructing both. Also initial pumping of cryostat and vacuum vessel of SST-1 will release a large amount of gas. Exhausted gases from SST -1 will be Hydrogen, Nitrogen, Mixture gases or some toxic gases. Dedicated exhaust system controlling the different gases are installed. Special treatment of hazardous/explosive gases is done before releasing to the atmosphere. This paper describes design and implementations of the complete gas feed and exhaust system of SST-1.

This paper represents the design of multi-beam (sixty-beam) electron gun and focusing system for high power, compact klystron. The beam voltage is 4 kV with a total beam current of 513 (8.55 × 60) mA which is equally divided among sixty-beam. Each beam has a perveance of 0.033 μP making a total gun perveance of 2.02 μP corresponding to a total beam power of more than 2 kW. The cathode radius is7 mm and individual emitter radius is 0.2 mm having current density 6.7 A/cm2. The design has been accomplished using OPERA 3D code. All beamlets have individual anode as well as BFE and a common focusing system. Potential difference between cathode and anode is 4 kV. A magnetic field of 1200 Gauss is applied along the beam axis. A major challenge for the development of multi-beam klystron is design and technology for the focusing of off-axis beamlets because off-axis beams are at various azimuths.

Vacuum vessel In-Wall Shield (IWS) will be inserted between the inner and outer shells of the ITER vacuum vessel. The behaviour of IWS in the vacuum vessel especially concerning the susceptibility to crevice of shielding block assemblies could cause rapid and extensive corrosion attacks. Even galvanic corrosion may be due to different metals in same electrolyte. IWS blocks are not accessible until life of the machine after closing of vacuum vessel. Hence, it is necessary to study the susceptibility of IWS materials to general corrosion and crevice corrosion under operations of ITER vacuum vessel. Corrosion properties of IWS materials were studied by using (i) Immersion technique and (ii) Electro-chemical Polarization techniques. All the sample materials were subjected to a series of examinations before and after immersion test, like Loss/Gain weight measurement, SEM analysis, and Optical stereo microscopy, measurement of surface profile and hardness of materials. After immersion test, SS 304B4 and SS 304B7 showed slight weight gain which indicate oxide layer formation on the surface of coupons. The SS 430 material showed negligible weight loss which indicates mild general corrosion effect. On visual observation with SEM and Metallography, all material showed pitting corrosion attack. All sample materials were subjected to series of measurements like Open Circuit potential, Cyclic polarization, Pitting potential, protection potential, Critical anodic current and SEM examination. All materials show pitting loop in OC2 operating condition. However, its absence in OC1 operating condition clearly indicates the activity of chloride ion to penetrate oxide layer on the sample surface, at higher temperature. The critical pitting temperature of all samples remains between 100° and 200°C.

Electron gun is extensively used in material processing, physical vapour deposition and atomic vapour based laser processes. In these processes where the electron beam is incident on the substrate, a significant fraction of electron beam gets back-scattered from the target surface. The trajectory of this back scattered electron beam depends on the magnetic field in the vicinity. The fraction of back-scattered depends on the atomic number of the target metal and can be as high as ∼40% of the incident beam current. These back-scattered electrons can cause undesired hot spots and also affect the overall process. Hence, the study of the trajectory of these back-scattered electrons is important. This paper provides the details of experimentally mapped back-scattered electrons of a 2×20kW Twin Electron Beam Gun (TEBG) in opposed magnetic field i.e. with these guns placed at 180° to each other.

In vacuum technology, metal gasket seals are extensively employed to achieve a UHV with reduced contamination considering the pressure and temperature variations as it performs a static seal between two stationary members of a mechanical assembly. The optimum sealing is attained over the balancing of the forces effective, which are function of temperature, governs the surface deformation for the metal gasket seal follows into degradation in the leak tightness at elevated temperatures. The prime component exerting the most deformation force over metal gasket seals, gasket seating force is a constant value generated by the bolting of the stationary members of a mechanical assembly. The paper address to metal gasket seals, copper and aluminum, behavior under thermo-mechanical load is analyzed (simulation), with ANSYS platform, workbench. The major concern is to investigate the typical deformation behavior as a function of thermal variation, baking/ cooling. For copper and Aluminum gasket seals, 16mm to 250mm internal diameter, exposed to pre-established gasket seating force under wide temperatures range. The deformation, average and the deformation range, observed to move in a very specific manner and runs to a wide range for a given material and size. The data reported here deserves to be substantial enough to establish the prediction of thermal behavior of metal gasket seals for standardization.

Thin films of Non-evaporable getter (NEG) Ti–Nb–Zr, have been deposited using a DC magnetron sputtering technique. The NEG films were produced from a Ti–Nb–Zr target in the form twisted wires of pure individual metals combined to give the appropriate stoichiometry. The performance and morphology dependence on deposition pressure, sputtering conditions and substrate surface roughness are investigated. Energy dispersive X-ray and X-ray photoelectron spectroscopic techniques are utilized to characterize and study the activation behaviour of the NEG thin films. After characterizing with surface techniques the activation temperature of this alloy is found to be in the range 250 – 300°C for 2 h heating with well defined composition. It is seen that film topography and density depend largely on the substrate surface roughness, while the activation temperature depends almost exclusively on the final stoichiometry of the thin film.

A 60 cm diameter spherical high-vacuum target-chamber with side-opening hemispherical-lids, two ancillary-chambers, beam-line-tubes, tees and other high-vacuum components, and chamber-lid handling systems have been designed, constructed and installed for the Charged Particle Detector Array in BARC-TIFR Pelletron-LINAC Facility, Mumbai. This array of several tens of Si-CsI detector modules and other ancillary-detectors will be used for investigations in fusion-fission dynamics, nuclear structure at elevated temperatures and angular momenta, exotic nuclear clusters and related fields. This paper describes the unique features of the system that aid different coincidence experiments, the chamber fabrication experience and the pump-down characteristics with a turbo molecular pump. Unlike many other target chambers in use, this chamber allows multiple overall geometrical configurations to be set to reach experimental goals. For instance, by replacing a hemispherical-lid from one side with a flat-lid, the overall configuration becomes hemispherical. This way, high geometrical efficiency can be provided to an ancillary gamma detector array by allowing it to move close to target from the flat-lid side, although with some sacrifice of geometrical efficiency for charged particles. In experiments where a further improvement of geometrical efficiency for a gamma array is desired, a third compact-cylinder configuration can also be arrived at. Thinned portion of the lids of the chamber also allow neutron coincidence measurements with charged particles and gamma rays.

The Super-Conducting Fragment Separator (Super FRS) of the Facility for Antiproton and Ion Research (FAIR) at GSI Darmstadt is a large-acceptance superonducting fragment separator. The separator consists of large dipole, quadrupole and hexapole superconducting magnets. The long quadrupole magnet cryostat houses the helium chamber, which has the magnet iron and NbTi superconducting coil. The magnet weighs about 30 tons. The helium chamber is enclosed in vacuum inside the magnet cryostat. Multilayer Insulation (MLI) will be wrapped around the thermal shield to reduce radiation loss. Polyster of MLI comprises the major component responsible for outgassing. In order to reduce outgassing, pumping at elevated temperatures has to be carried out. In view of the large size and weight of the magnet, a seal off approach might not be operationally feasible. Continuous pumping of the cryostat has also been examined. Pump has been kept at a distance from the magnet considering the effect of stray magnetic fields. Oil free turbo molecular pump and scroll pump combination will be used to pump down the cryostat. The ultimate heat load of the cryostat will be highly dependent on the pressure attained. Radiation and conduction plays an important role in the heat transfer at low temperatures. This paper presents the vacuum design of the long quadrupole magnet cryostat and estimates the heat load of the cryostat.

ADITYA (R0 = 75 cm, a = 25 cm), an ohmically heated circular limiter tokamak is regularly being operated to carry out several experiments related to controlled thermonuclear fusion research. In recent operational campaign, various experiments have been carried out to enhance the discharge performance as well as improve the plasma parameters. A comparative plasma discharges study with SiC and Graphite limiter was carried out to increase the plasma heating and reduce runaways. Excellent plasma heating has been observed in many discharges using Graphite limiter. Good repeatability of low hard X-rays, high temperature discharges was obtained. The control of plasma impurities and hydrogen recycling is very much essential for high performance discharges. The wall conditioning in ADITYA tokamak is carried out by hydrogen glow discharge cleaning (GDC), Pulse discharge cleaning and electron cyclotron resonance (ECR) discharge cleaning techniques with and without lithium wall coating. GDC assisted Lithiumization was found to be the most effective technique for substantial reduction in Ha and low Z (CIII & O-I) impurities. The partial pressure of mass number 18 (H2O) and 28 (N2/C2H4/CO) were regularly monitored before plasma discharge operation. Furthermore, experiment on optimization of pulse gas feed was helped in reducing wall loading and recycling. However, hard X-rays suppression with the application of multiple gas puff has been successfully achieved during negative converter operation, which led to the extension of plasma pulse length up to ∼ 250 ms. All the supporting facts and operation aspects are reported.

The water vapour contained in the atmosphere contaminates a vacuum systems, when it is exposed to air. The degree of contamination will depend on the surface characteristics, treatment of the system walls, the relative humidity and the turbulence of air, the amount of time the system is opened to the atmosphere, etc. If the temperature of the exposed surface is low, possibility of water condensing on the surface exists. In order to study the effect and optimise procedure for achieving high vacuum in a vacuum chamber initially containing water, a vacuum chamber has been fabricated. Pump down time has been measured for different amount of water placed in the vacuum chamber with varying pumping speeds. The paper presents a review of similar activities and results of the experimental study.

The vacuum system for K-130 cyclotron has been operational since 1977. It consists of two sub-systems, main vacuum system and beam line vacuum system. The main vacuum system is designed to achieve and maintain vacuum of about 1 × 10⁻⁶ mbar inside the 23 m³ volume of acceleration chamber comprising the Resonator tank and the Dee tank. The beam line vacuum system is required for transporting the extracted beam with minimum loss. These vacuum systems consist of diffusion pumps backed by mechanical pumps like roots and rotary pumps. The large vacuum pumps and valves of the cyclotron vacuum system were operational for more than twenty five years. In recent times, problems of frequent failures and maintenance were occurring due to aging and lack of appropriate spares. Hence, modernisation of the vacuum systems was taken up in order to ensure a stable high voltage for radio frequency system and the extraction system. This is required for efficient acceleration and transportation of high intensity ion beam. The vacuum systems have been upgraded by replacing several pumps, valves, gauges and freon units. The relay based control system for main vacuum system has also been replaced by PLC based state of the art control system. The upgraded control system enables inclusion of additional operational logics and safety interlocks into the system. The paper presents the details of the vacuum system and describes the modifications carried out for improving the performance and reliability of the vacuum system.

SMall Aspect Ratio Toroidal Experiments in a C-shaped trap (SMARTEX-C) attempts to confine electrons in a toroidal trap using static electric and magnetic field. Confinement of these electrons is largely limited by charge losses due to the presence of background neutrals and by short pulsed magnetic field. Ions formed due to electron impact ionization of background neutrals lead to instabilities that are ultimately observed to limit the confinement. Lowering the amount of neutrals in the trap is therefore of paramount importance. In SMARTEX-C, prior to electron injection, the trap is pumped down to base pressures of the order of 2 ± 1 × 10⁻⁸ mbar. However, as one turns on the electron source (tungsten filament emitting thermionically) pressure in the system increases to ∼ 1 × 10⁻⁷mbar. Partial pressure analysis of the vacuum system indicates predominant presence of H₂ during filament operation. Replacing the copper current-leads for electron source with stainless steel-304 led to reduction of H2 outgassing. Additionally, viton seals have been replaced with Aluminum wire-seals that allow baking at elevated temperatures and further reduce out-gassing. All these measures have led to an improvement in the base pressure to 7±1 × 10⁻⁹ mbar even during filament operation. Confinement of electron plasmas in the trap has thus significantly improved.

Helium leak detection of vacuum furnaces and equipments used for processing of nuclear material is generally carried out by utilizing vacuum spray technique. In this technique helium leak detector is connected to the furnace, back ground reading is noted and helium gas is sprayed on all the suspected joints. Any increase in back ground is noted as leak signal. Processing of Zirconium alloy cladded fuel pins is carried out in vacuum furnace of about 3 meter length and 500 mm inside diameter. Furnace is connected with two numbers of rotary vacuum pump and one number of diffusion pump for creating vacuum (1 × 10⁻⁶ torr) inside the furnace. It is desirable that furnace should have good vacuum and best possible leak tightness during dynamic and static vacuum. During dynamic vacuum at higher temperature although required vacuum is achieved the furnace may have fine leakage through which air may enter and cause oxidation of clad tube leading to change in its coloration. This change in coloration will cause rejection of fuel element. Such fine leakages may not be reflected in the dynamic vacuum of the system at high temperature. During trial run change in coloration of outside surface of clad tube was observed although dynamic vacuum of the furnace was in the range of 1×10⁻⁶ torr range. To eliminate such possibilities of oxidation due to fine leakages in the system, it was decided to carry out in-service leak testing of the furnace. Helium leak testing of the furnace was carried out by using vacuum spray method and leaks observed were repaired and furnace was retested to ensure the leak tightness. The in-service helium leak testing of the furnace helped in maintaining its leak tightness during service under dynamic vacuum and prevent oxidation of fuel element. This paper describes the techniques of in- service helium leak testing, it's importance for detection of fine leak under dynamic vacuum and discusses details of the testing method and result obtained.

Electron beam heating is a technique to generate vapor of refractory and high melting point metals. Vapor production finds application in thin film deposition and laser-based purification of materials. A strip electron-gun whose filament is heated by AC current is generally used because of larger molten pool formation and quiet evaporation. Electron-gun thus generates vapor. The incident beam of electrons is backscattered with large angular distribution. Both the electron groups, namely the primary and the backscattered electrons participate in production of plasma by electron-impact ionization. The plasma is weakly ionized (∼ 0.1% degree of ionization) with ion density ∼ 10⁸ cm⁻³ and has low electron temperature (∼ 0.3 eV). The vapor and the simultaneously produced plasma expand in the space above the target. Plasma expands by ambipolar diffusion in a transverse magnetic field while the vapor expands as a collision-less atomic beam. In this paper we study vapor and plasma formation of copper and zirconium. Details shall be discussed.

Electron beam is preferably used for large scale evaporation of refractory materials. Material evaporation from a long and narrow source providing a well collimated wedge shaped atomic beam has applications in isotopic purification of metals relevant to nuclear industry. The electron beam from an electron gun with strip type filament provides a linear heating source. However, the high power density of the electron beam can lead to turbulence of the melt pool and undesirable splashing of molten metal. For obtaining quiet surface evaporation, the linear electron beam is generally scanned along its length. To further reduce the power density to maintain quiet evaporation the width of the vapour source can be controlled by rotating the electron gun on its plane, thereby scanning an inclined beam over the molten pool. The rotation of gun has further advantages. When multiple strip type electron guns are used for scaling up evaporation length, a dark zone appears between two beams due to physical separation of adjacent guns. This dark zone can be reduced by rotating the gun and thereby bringing two adjacent beams closer. The paper presented here provides the simulation results of the electron beam trajectory and incident power density originating from two strip electron guns by using in-house developed code. The effect of electron gun rotation on the electron beam trajectory and power density is studied. The simulation result is experimentally verified with the image of molten pool and heat affected zone taken after experiment. This technique can be gainfully utilized in controlling the time averaged power density of the electron beam and obtaining quiet evaporation from the metal molten pool.

Nano science and nanotechnology continue to grow as fields of scientific research and commercial development. At this time, focus is to develop the particles of desired size with significant change of properties than bulk material. But the sample preparation methods involved in each process, surface functionlization and existing characterization techniques remains an important and complicated issue of nanoscience for the development of new materials till the present date. Thus for a science, that is all about size, these important size issues need to be fully understood as it impacts not only the electronic and optical properties but also environmental and biological interactions. We are producing metal nanoparticles by exploding wire method. Vacuum plays an important role in the production of pure nanopowder as well as to avoid contamination and storage of the material to produce stable nanoparticles. In this paper we will discuss about the complications and intermediate process involved in the production of nano crystalline by exploding wire method.

A steady state superconducting Tokamak SST-1 is presently under its assembly stage at the Institute for Plasma Research. The SST-1 machine is a family of Superconducting SC coils for both Toroidal field and Poloidal Field. An ultra high vacuum compatible vacuum vessel, placed in the bore of the TF coils, houses the plasma facing components. A high vacuum cryostat encloses all the SC coils and the vacuum vessel. Liquid Nitrogen (LN₂) cooled thermal shield between the vacuum vessel & SC coils as well as between cryostat and the SC coils. There are number of crucial cryogenic components as Electrical isolators, 80 K thermal shield, Cryogenic flexible hose etc., which have to be passed the performance validation tests as part of fulfillment of the stringent QA/QC before incorporated in the main assembly. The individual leak tests of components at RT as well as after thermal cycle from 300 K to 77 K ensure us to make final overall leak proof system. These components include, Large numbers of Electrical Isolators for Helium as well as LN₂ services, Flexible Bellows and Hoses for Helium as well as LN₂ services, Thermal shock tests of large numbers of 80 K Bubble shields In order to validate the helium leak tightness of these components, we have used the calibrated mass spectrometer leak detector (MSLD) at 300 K, 77 K and 4.2. Since it is very difficult to locate the leaks, which are appearing at rather lower temperatures e.g. less than 20 K, We have invented different approaches to resolve the issue of such leaks. This paper, in general describes the design of cryogenic flexible hose, assembly, couplings for leak testing, test method and techniques of thermal cycles test at 77 K inflow conditions and leak testing aspects of different cryogenic components. The test results, the problems encountered and its solutions techniques are discussed.

In this paper, we report on the development of a brazing process for an ultra-high vacuum (UHV) compatible photocathode RF gun structure developed at our Centre. The choice of brazing alloy and its form, brazing clearance between parts to be joined and the brazing cycle adopted have been qualified through metallographic examination of identical joints on an OFE copper prototype that was cut open after brazing. The quality of brazed joint not only affects the UHV compatibility of the gun, but also influences the RF parameters finally achieved. A 2-D electromagnetic code, SUPERFISH, was used to predict the variation in RF parameters before and after brazing considering actual brazing clearances provided between the parts to be joined. Results obtained from low power RF measurements on the brazed gun structure confirm the integrity of the brazed joints and show good agreement with those predicted by electromagnetic simulations. The brazed gun structure has been leak-tested and pumped down to a vacuum level limited by the vacuum compatibility of the flange-fittings employed in the setup.

VECC has undertaken the modernization of the K-130 Room Temperature Cyclotron (RTC) (operational since 1978) and commissioning of K-500 Superconducting Cyclotron (SCC) at present. The control system of RTC vacuum system has been upgraded to Programmable Logic Controller (PLC) based automated system from relay based manual system. A distributed PLC based system is under installation for SCC vacuum system. The requirement of high vacuum in both the cyclotrons (1×10⁻⁶ mbar for RTC and 5 × 10⁻⁸ mbar SCC) imposes the reliable local and remote operation of all vacuum components and instrumentation. The design and development of the vacuum control system of two cyclotrons using the Experimental Physics and Industrial Control System (EPICS) distributed real-time software tools are presented.

We use a three stage vacuum system for developing a dilution fridge at VECC, Kolkata. We aim at achieving a cooling power of 20μW at 100mK for various experiments especially in the field of condensed matter and nuclear physics. The system is essentially composed of four segments-bath cryostat, vacuum system, dilution insert and ³He circulation circuit. Requirement of vacuum system at different stages are different. The vacuum system for cryostat and for internal vacuum chamber located within the helium bath is a common turbo molecular pump backed by scroll pump as to maintain a vacuum ∼10⁻⁶mbar. For bringing down the temperature of the helium evaporator, we use a high throughput Roots pump backed by a dry pump. The pumping system for ³He distillation chamber (still) requires a high pumping speed, so a turbo drag pump backed by a scroll pump has been installed. As the fridge use precious ³He gas for operation, the entire system has been made to be absolutely leak proof with respect to the ³He gas.

A high vacuum sample preparation system for the ³He/⁴He ratio mass spectrometer (Helix SFT) has been developed to remove all the gaseous constituents excluding helium from the field gases. The sample preparation system comprises of turbo molecular pump, ion pump, zirconium getter, pipettes and vacuum gauges with controller. All these are fitted with cylindrical SS chamber using all metal valves. The field samples are initially treated with activated charcoal trap immersed in liquid nitrogen to cutoff major impurities and moisture present in the sample gas. A sample of 5 ml is collected out of this stage at a pressure of 10⁻² mbar. This sample is subsequently purified at a reduced pressure of 10⁻⁷ mbar before it is injected into the ion source of the mass spectrometer. The sample pressure was maintained below 10⁻⁷ mbar with turbo molecular vacuum pumps and ion pumps. The sample gas passes through several getter elements and a cold finger with the help of manual high vacuum valves before it is fed to the mass spectrometer. Thus the high vacuum sample preparation system introduces completely clean, dry and refined helium sample to the mass spectrometer for best possible analysis of isotopic ratio of helium.

For all accelerators and many research and industries, excellent vacuum conditions are required and the highest possible pumping rates are necessary. For most applications the standard ion sputtering pump (ISP) meets these requirements and is optimal for financial point of view also. The physical principle of the ISP is well known and many companies manufacture variety of ISP. Most of them use dipole magnetic field produced by permanent magnet and electric dipole field between the electrodes in which tenuous plasma is created because of interaction of between the relatively fast electrons slow residual gas atoms. Performance of an ISP depends basically on the electron cloud density in between the titanium electrodes but in the available present configurations no consideration has been given to electron confinement which needs a mirror magnetic field. If this is incorporated it will make a robust ISP surely; furthermore, the requirement of constant feeding of high voltage to electrodes for supplying sufficient number of electrons will be reduced too. A study has been performed to create sufficient rotationally symmetric spindle magnetic field (SMF) with inherent presence of magnetic mirror effect to electron motion to confine them for longer time for enhancing the density of electron cloud between the electrodes. It will lessen the electric power feeding the electrodes and lengthen their life-time. Construction of further compact and robust ISP is envisaged herein. The field simulation using the commercially available permanent magnet together with simulation of electron motion in such field will be presented and discussed in the paper.

Short duration, high power pulses with fast rise time and good flat-top are essentially required for driving pulsed electron beam diodes. To attain this objective, a dual resonant Tesla transformer based pulsed power accelerator 'AMBICA-600' has been developed. In this newly developed system, a coaxial water line is charged through single turn Tesla transformer that operates in the dual resonant mode. For making the accelerator compact, in the high power pulse forming line, water has been used as dielectric medium because of its high dielectric constant, high dielectric strength and high energy density. The coaxial waterline can be pulsed charged up to 600kV, has impedance of ∼5Ω and generates pulse width of ~60ns. The integrated system is capable of producing intense electron beam of 300keV, 60kA when connected to impedance matched vacuum diode. In this paper, system hardware details and experimental results of gigawatt electron beam generation have been presented.

In this investigation, tungsten oxide (WO₃) thin films have been deposited on unheated glass substrates by RF magnetron sputtering of tungsten target at constant oxygen partial pressure of 6×10⁻² Pa, sputtering power of 150 W and at different substrate bias voltages in the range from 0 to -150 V. The structural and optical properties of the films were investigated by using X-ray diffraction, Fourier transform infrared spectroscopy and UV-Vis-NIR spectrophotometers. The films formed up to substrate bias voltage of -50 V were found to be amorphous in nature, while those films formed at -100 V showed a weak (200) reflection indicates the presence of monoclinic phase of WO₃ in amorphous matrix. The optical transmittance of the films was in the range 78 – 95 % in the wavelength range of 500 – 1200 nm. The absorption band edge was shifted towards higher wavelength side with increasing substrate bias voltage. The optical band gap of the films decrease from 2.81 to 2.69 eV with increase of substrate bias voltage from 0 to -150 V respectively. The refractive index of the films increased from 2.19 to 2.27 with increase of substrate bias voltage from 0 to -150 V respectively.

A conceptual design of vacuum chamber is proposed to study the thermal response of high heat flux components under energy depositions of the magnitude and durations expected in plasma fusion devices. It is equipped with high power electron beam with maximum beam power of 200 KW mounted in a stationary horizontal position from back side of the chamber. The electron beam is used as a heat source to evaluate the heat removal capacity, material performance under thermal loads & stresses, thermal fatigue etc on actively cooled mock – ups which are mounted on a flange system which is the front side door of the chamber. The tests mock – ups are connected to a high pressure high temperature water circulation system (HPHT-WCS) operated over a wide range of conditions. The vacuum chamber consists of different ports at different angles to view the mock -up surface available for mock -up diagnostics. The vacuum chamber is pumped with different pumps mounted on side ports of the chamber. The chamber is shielded from X – rays which are generated inside the chamber when high-energy electrons are incident on the mock-up. The design includes development of a conceptual design with theoretical calculations and CAD modelling of the system using CATIA V5. These CAD models give an outline on the complete geometry of HHF test chamber, fabrication challenges and safety issues. FEA analysis of the system has been performed to check the structural integrity when the system is subjected to structural & thermal loads.

A low impedance Marx generator was developed, which will serve as a test bed for Vacuum diodes of various electrode materials and geometries. The vacuum diodes will be used for high power microwave generation. The generator is capable to supply ∼3GW of pulsed power to the vacuum diodes which is sufficient enough to produce plasma within the diode for electron beam generation. A vacuum of 10⁻⁵Torr is required for virtual cathode formation within the diode, when the beam current exceeds the space charge limiting current. A vacuum diode of reflex triode geometry has been designed and vacuum of 10⁻⁵ Torr has been achieved. The repetitive operation of the vacuum diode depends upon the recovery of the diode, the importance of the vacuum system on the recovery of the diode will be explained. A vacuum system with high voltage isolator has been installed for getting the desired vacuum within the diode. The design criterion of the vacuum system will be discussed. The 300kV/1.8kJ Marx generator which will power the vacuum diode has six stages with stage capacitance and voltage of 240nF and 50kV respectively. It has an impedance of ∼7 ohm and can deliver 200kV voltage across the diode in critically damped load condition. The generator has a very fast rise time of 200ns.The operational characteristics of the Marx generator are determined experimentally. The results have been analyzed and compared to an equivalent circuit model of the system.

This paper describes the vacuum system design for a 20-cell Plane Wave Transformer (PWT) type LINear ACcelerator (LINAC) structure to obtain a vacuum better than 5×10⁻⁸ mbar everywhere inside the linac structure. Specific material out-gassing rate for a 20-cell linac is determined on the basis of vacuum achieved in a similar type of 8-cell linac structure, which is smaller in length, and presently under operation in the Compact Ultrafast TEra-hertz Free Electron Laser (CUTE-FEL) beam transport line at RRCAT.

Advanced fusion reactors like ITER and up coming Indian DEMO devices are having challenges in terms of their materials design and fabrication procedures. The operation of these devices is having various loads like structural, thermo-mechanical and neutron irradiation effects on major systems like vacuum vessel, divertor, magnets and blanket modules. The concept of double wall vacuum vessel (VV) is proposed in view of protecting of major reactor subsystems like super conducting magnets, diagnostic systems and other critical components from high energy 14 MeV neutrons generated from fusion plasma produced by D-T reactions. The double walled vacuum vessel is used in combination with pressurized water circulation and some special grade borated steel blocks to shield these high energy neutrons effectively. The fabrication of sub components in VV are mainly used with high thickness SS materials in range of 20 mm- 60 mm of various grades based on the required protocols. The structural components of double wall vacuum vessel uses various parts like shields, ribs, shells and diagnostic vacuum ports. These components are to be developed with various welding techniques like TIG welding, Narrow gap TIG welding, Laser welding, Hybrid TIG laser welding, Electron beam welding based on requirement. In the present paper the samples of 20 mm and 40 mm thick SS 316 materials are developed with TIG welding process and their mechanical properties characterization with Tensile, Bend tests and Impact tests are carried out. In addition Vickers hardness tests and microstructural properties of Base metal, Heat Affected Zone (HAZ) and Weld Zone are done. TIG welding application with high thick SS materials in connection with vacuum vessel requirements and involved criticalities towards welding process are highlighted.

Non evaporable getter (NEG) coating technology development started at UHVTD, Raja Ramanna Centre for Advanced Technology (RRCAT). An UHV compatible, cylindrical magnetron sputtering system for Ti-Zr-V (Titanium-Zirconium-Vanadium) NEG coating was designed, developed and successfully installed at UHVTD, RRCAT. Surface studies play important role in this technology development. Inside surfaces of many vacuum chambers were coated with varying thickness and compositions using this setup. Preliminary studies of adhesion, crystallographic structure & size of crystallites, surface morphology, trapping of argon gas during coating and its release after getter activation were carried out and some results are reported in this paper.

Thin films of ZnO were synthesised on glass substrate by dc sputtering technique at a system pressure of 10⁻⁴ Torr. A layer of TiO₂ was deposited onto the above ZnO films by high pressure sputtering technique. The composite structure was then subjected to rapid thermal annealing at a pressure of 10⁻² Torr in argon ambience. Microstructural and compositional analyses were carried out by SEM, EADX and XRD studies. The optical band gap pure ZnO (∼3.45 eV) was found to shift to higher energy (∼3.54 eV) for the ZnO/Ti structures. FTIR measurement indicated the presence of a prominent absorption peak at ∼490 cm⁻¹ due to ZnO stretching mode. Methane gas sensing measurement was carried out at 353K, indicated that the highest sensitivity was nearly 60% with a response time ∼52 min when the film were exposed to 10 % vol. of methane gas.

A 2.45 GHz microwave ion source and the transport system of high current proton beam for injection study in a compact cyclotron have been designed, fabricated indigenously, installed and commissioned. Presently it is under testing for beam characterization and inflection study. The vacuum system consists of a plasma chamber with 8mm slit in the plasma electrode, two-segment ceramic insulators (Al2O3) column, which supports the beam extraction electrodes and isolates the high voltage deck from the beam line and a 3m long low energy beam transport line (LEBT) equipped with several diagnostic elements such as faraday cup, slits, beam viewer etc. There is a provision to connect a needle valve to feed gas into the chamber for beam space charge neutralization studies. An online vacuum data logging software has been developed for continuous monitoring of the vacuum near the extraction zone. Monitoring system being very sensitive to the high voltage breakdown, is designed with a spark protection circuit which provides an isolation of 10kV using an optical isolation technique. In this paper we present design philosophy, operating experience and some experimental results. We have studied the behaviour of vacuum system near the extraction zone under various operating conditions of the high current ion source.

Graphene, an allotrope of carbon is a two-dimensional sheet of covalently bonded carbon atoms that has been attracting great attention in the field of electronics. In a recent review graphene is defined as a flat monolayer of carbon atoms tightly packed into a 2-D honeycomb lattice. A survey has been made of the production processes and instrumentation for characterization of graphene. In the production of graphene, the methods mainly used are Epitaxial growth, oxide reduction, growth from metal-carbon melts, growth from sugar. In the characterization of graphene, the instruments that are mainly used to study the atomic properties, electronic properties, optical properties, spin properties are Scanning Electron Microscopy, Transmission Electron Microscopy, Raman Spectroscopy. In all these instruments high or ultra-high vacuum is required. This paper attempts to correlate vacuum technology in the production and characterization of graphene.

Cryosorption pump is the only solution for pumping helium and hydrogen in fusion reactors. It is chosen because it offers highest pumping speed as well as the only suitable pump for the harsh environments in a tokamak. Towards the development of such cryosorption pumps, the optimal choice of the right activated carbon panels is essential. In order to characterize the performance of the panels with indigenously developed activated carbon, a cryocooler based cryosorption pump with scaled down sizes of panels is experimented. The results are compared with the commercial cryopanel used in a CTI cryosorption (model: Cryotorr 7) pump. The cryopanel is mounted on the cold head of the second stage GM cryocooler which cools the cryopanel down to 11K with first stage reaching about ∼50K. With no heat load, cryopump gives the ultimate vacuum of 2.1E-7 mbar. The pumping speed of different gases such as nitrogen, argon, hydrogen, helium are tested both on indigenous and commercial cryopanel. These studies serve as a bench mark towards the development of better cryopanels to be cooled by liquid helium for use with tokamak.

In this paper, we report fabrication and testing of a unique Faraday Cup designed for qualification of Electron Gun for a 10 kW industrial LINAC. This is a compact device consisting of a tapered copper cavity electrically isolated by a ceramic cylinder metalized at both ends. Kovar tubes matching with the diameter of ceramic isolator were used at both ends to facilitate high quality UHV compatible joints with copper cavity at one end and standard knife edge stainless steel flange at the other end. The Kovar tube was flared at both ends to form a collar matching with the outer diameter of the ceramic isolator. The joint between Kovar collar and ceramic isolator was done by hydrogen brazing using copper silver eutectic alloy. All the joints were tested with helium leak detector and leak rates were found to be below 1 × 10⁻¹⁰mbar.litre/second.

Transport of a low-current-density electron beam is simulated for an electrostatic accelerator system. Representative charged particles are uniformly assigned for emission from a circular indirectly-heated cathode of an axial electron gun. The beam is accelerated stepwise up to energy of 1 MeV electrostatically in a length-span of ~3 m using multiple accelerating electrodes in a column of ten tubes. The simulation is done under relativistic condition and the effect of the magnetic field induced by the cathode-heating filament current is taken into account. The beam diameter is tracked at different axial locations for various settings of the electrode potentials. Attempts have been made to examine and explain data on beam transport efficiency obtained from experimental observations.

Electrons guns for RF linacs and DC Accelerators are designed and developed at Electron Beam Centre (EBC)/APPD/BARC. Planar geometry grid and Pierce geometry grid configuration diode and triode guns with LaB6 cathode are developed. The cathode assembly consists of cups and heat shields made out of Tantalum and Rhenium sheets. The cathode assembly and the electron guns are tested on a test bench for beam characterization. The paper presents the development of the electron guns.

This paper reports the optical and electrical characterization of sinusoidal and pulse glow-discharge plasma in helium. A homogeneous type of discharge has been observed for different operating conditions in helium DBD. The image of discharges makes sure that the diffuse discharge covers the entire surface of the electrodes. Optical emission spectroscopy has been used to determine the main emission lines of the helium glow discharge plasma. The internal plasma parameters of DBDs have been investigated at different operating conditions. It has been observed that the DBDs are becoming more intense with increase in pressure and applied power. The effect of the excitation mechanism on the emission properties and discharge parameters for the helium DBD is studied experimentally and further analysed by using plasma simulation tool OOPIC-Pro.

The pseudospark (PS) discharge is, however, more recently recognized as a different type of discharge which is capable of generating electron beams with the highest combined current density and brightness of any known type of electron source. PS discharge is a specific type of gas discharge, which operates on the left-hand side of the hollow cathode analogy to the Paschen curve with axially symmetric parallel electrodes and central holes on the electrodes. The PS discharge generated electron beam has tremendous applications in plasma filled microwave sources where normal material cathode cannot be used. Analysis of the electron beam profile has been carried out experimentally for different applied voltages. The investigation has been done at different axial and radial location inside the drift tube in argon atmosphere. This paper represents experimentally derived axial and radial variation of the beam current inside the plasma filled drift tube of PS discharge based plasma cathode electron (PCE) gun. With the help of current density estimation the focusing and defocusing point of electron beam in axial direction can be analyzed. It has been further confirmed the successful propagation of electron beam in confined manner without any assistance of external magnetic field.

Sheet Beam Klystron (SBK) is a device employing rectangular/elliptical cross section beam. The barbell cavity for SBK has been designed providing uniform flat electric field profile across the width of the cavity. The loop coupling arrangement has also been designed using CST Microwave studio software tool and optimized for maximum return loss. The designed barbell cavity has been re-optimized after the insertion of the loop coupling to provide flat electric field profile across the width of the cavity. The cavity has also been fabricated and initial characterization has been carried out. The simulated results and the experimental results matches closely.

A large, segmented, horizontal axis, reaction chamber (SHARC) has recently been fabricated, installed and integrated with the beam line in the VECC superconducting cyclotron (SCC) experimental area. It is a cylindrical, three segment, stainless steel chamber of length 2.2 m, diameter 1 m. Two pairs of parallel rails have been provided internally for placement of the target assembly and detector systems within the chamber. The whole target assembly can be placed anywhere on the rail to facilitate optimum flight path. The nominal vacuum of ∼1×10⁻⁷ mbar has been obtained in ∼8 hrs by means of two turbo molecular (1000 l/s) and two cryo pumps (2500 l/s) backed by mechanical pumps. The whole vacuum system as well as the target positioning (vertical and rotational movements) operations are fully automated with manual override option; both are monitored and controlled locally as well as remotely through the local and remote control units providing real time status display.

The paper presents the design and development of collector for C-band 250 kW high power klystron. The design criteria for the collector assembly is selection of material, vacuum and high temperature compatibility, proper electron beam dispersion, minimum back scattering of electrons and thermal design for proper cooling at high power dissipation. All these aspects have been discussed for collector development in details. The collector has been designed in TRAK and then beam propagation has been analyzed in MAGIC 2D software. The thermal simulation has been done using ANSYS 11.0 (multi-physics). The outer surface of the collector has been grooved to facilitate its proper cooling. Design results are presented for water cooling with different flow rates and channel dimensions. OFHC copper material is chosen for collector which is suitable for vacuum and hydrogen brazing operations and good thermal properties for efficient cooling.

Cryosorption pump is the only solution to pump helium, hydrogen and its isotopes in fusion devices. To design such pumps, knowledge of adsorption characteristics of activated carbons in the temperature range from 4.5 to 77 K is needed, but is very scarce in the open literature. Hence an experimental setup is designed and developed to measure adsorption characteristics of activated carbons down to 4.5 K. For this purpose, a commercial micropore analyzer operating down to 77K is coupled to a two-stage GM cryocooler, to enable cooling the sample temperature down to 4.5 K. A heat switch is mounted in between the second stage cold head and the sample chamber helps to vary the sample temperature from 4.5 K to 77K without affecting the performance of the cryocooler. The details of the experimental setup is presented elsewhere. We present here the experimental results of adsorption of different types of activated carbons in the temperature range 4.5K to 10 K using Helium gas as adsorbate. These results are evaluated in terms of surface area, pore sizes and their distributions. Also the effect of epoxy based adhesive used in bonding the activated carbons to the panels is evaluated. These results will be useful towards the selection of the right activated carbons for the development of cryosorption pumps.

Traveling Wave Tubes are the unique class of microwave amplifiers with broad bandwidth, which makes it preferred for space applications. The constraints for a space application are very stringent demanding compactness and less weight. Entire size of the tube is mainly decided by the size of the collector, as it is the bulkiest component in a tube. Hence, if the size of the collector is reduced then the entire tube size will reduce. Researches reveal that in order to reduce the size of the collector, application of the magnetic field is necessary. Therefore, to study the effect of magnetic field on the collector performance, a magneto-static solver module has been developed. This paper describes the development of the magneto-static solver.

A new and elaborate automatic vacuum protection system using fast acting valve has been installed to avoid accidental venting of accelerator from experimental chamber side. To cover all the beam lines and to reduce the system cost, it has been installed at a common point from where all the seven beam lines originate. The signals are obtained by placing fast response pressure sensing gauges (HV SENSOR) near all the experimental stations. The closing time of the fast valve is 10 milli-second. The fast closing system protects only one vacuum line at a time. At IUAC, we have seven beam lines so one sensor was placed in each of the beam lines near experimental chamber and a multiplexer was incorporated into the fast closing system. At the time of experiment, the sensor of the active beam line is selected through the multiplexer and the Fast closing valve is interlocked with the selected sensor. As soon as the pressure sensor senses the pressure rise beyond a selected pressure, the signal is transferred and the fast valve closes within 10 to 12 millisecond.

Bharatiya Nabhikiya Vidyut Nigam (BHAVINI) is engaged in construction of 500MW Prototype Fast Breeder Reactor (PFBR) at Kalpak am, Chennai. In this very important and prestigious national programme Special Product Division (SPD) of M/s Kay Bouvet Engg.pvt. ltd. (M/s KBEPL) Satara is contributing in a major way by supplying many important sub-assemblies like- Under Water trolley (UWT), Airlocks (PAL, EAL) Container and Storage Rack (CSR) Vessels in Fuel Transfer Cell (FTC) etc for PFBR. SPD of KBEPL caters to the requirements of Government departments like – Department of Atomic Energy (DAE), BARC, Defense, and Government undertakings like NPCIL, BHAVINI, BHEL etc. and other precision Heavy Engg. Industries. SPD is equipped with large size Horizontal Boring Machines, Vertical Boring Machines, Planno milling, Vertical Turret Lathe (VTL) & Radial drilling Machine, different types of welding machines etc. PFBR is 500 MWE sodium cooled pool type reactor in which energy is produced by fissions of mixed oxides of Uranium and Plutonium pellets by fast neutrons and it also breeds uranium by conversion of thorium, put along with fuel rod in the reactor. In the long run, the breeder reactor produces more fuel then it consumes. India has taken the lead to go ahead with Fast Breeder Reactor Programme to produce electricity primarily because India has large reserve of Thorium. To use Thorium as further fuel in future, thorium has to be converted in Uranium by PFBR Technology.

We have designed and developed an indigenous ultra high vacuum (UHV) sputtering system which can deposit magnetic thin films with high purity and good uniformity. The equipment consists of state-of the-art technologies and sophistication. Turbo-molecular pump combined with sputter ion pump is used to pump down the vacuum chamber up to 10⁻¹⁰ to 10⁻¹¹ mbar of pressure. With this system it is possible to deposit coatings of various materials on a sample size of diameter 3". The Ni₈₁Fe₁₉ ferromagnetic thin films, with Tantalum (Ta) as a buffer and cap layers have been deposited on silicon substrates using this ultra high vacuum (UHV) sputtering system. The magneto transport measurement study indicated a significant variation in the AMR values of the films for varying thicknesses of tantalum and NiFe layers.