In the last 30 days

• Open/close Plasma Diagnosis for Microwave ECR Plasma Enhanced Sputtering Deposition of DLC Films

  Pang Jianhua (庞见华) et al 2012 Plasma Sci. Technol. 14 172 Tag this article

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  Application of the Langmuir probe in plasma circumstance for deposition of diamond-like carbon (DLC) thin films usually faces the problem of rapid failure of the probe due to surface insulative coating. In this paper, we circumvent the problem by using the floating harmonic probe technique. In the real circumstance of DLC film deposition, the floating harmonic probe worked reliably over 3 hours, correctly indicating the ion density and electron temperature. The technique was practically used to measure the ion density and electron temperature in DLC film deposition processes using the microwave ECR plasma enhanced sputtering. Combined with the Raman spectroscopic characterization of the films, the conditions for deposition of DLC films were investigated.

• Open/close Electron Density and Optical Emission Measurements of SF₆/O₂ Plasmas for Silicon Etch Processes

  M. M. Morshed and S. M. Daniels 2012 Plasma Sci. Technol. 14 316 Tag this article

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  This work investigates internal plasma process parameters using a hairpin resonance probe and optical emission spectroscopy. The dependence of electron density and atomic fluorine on the percentage of oxygen in an SF ₆/O ₂ discharge was measured using these methods. An RIE Oxford Instruments 80 plus chamber was used for the experiments. Two different process powers (100 W and 300 W) at a constant pressure (100 mTorr) were used, and it was found that the optical emission intensity of the 703.7 nm and 685.6 nm lines of atomic fluorine increased rapidly as oxygen was added to the SF ₆ discharge, reached their maximum at an O ₂ fraction of 20% and then decreased with further addition of oxygen. The plasma electron density was also strongly influenced by the addition of O ₂.

• Open/close Plasma-Assisted ALD of an Al₂O₃ Permeation Barrier Layer on Plastic

  Lei Wenwen (雷雯雯) et al 2012 Plasma Sci. Technol. 14 129 Tag this article

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  Atomic layer deposition (ALD) technique is used in the preparation of organic/inorganic layers, which requires uniform surfaces with their thickness down to several nanometers. For film with such thickness, the growth mode defined as the arrangement of clusters on the surface during the growth is of significance. In this work, Al ₂O ₃ thin film was deposited on various interfacial species of pre-treated polyethylene terephthalate (PET, 12 μm) by plasma assisted atomic layer deposition (PA-ALD), where trimethyl aluminium was used as the Al precursor and O ₂ as the oxygen source. The interfacial species, -NH ₃, -OH, and -COOH as well as SiCHO (derived from monomer of HMDSO plasma), were grafted previously by plasma and chemical treatments. The growth mode of PA-ALD Al ₂O ₃ was then investigated in detail by combining results from in-situ diagnosis of spectroscopic ellipsometry (SE) and ex-situ characterization of as-deposited layers from the morphologies scanned by atomic force microscopy (AFM). In addition, the oxygen transmission rates (OTR) of the original and treated plastic films were measured. The possible reasons for the dependence of the OTR values on the surface species were explored.

• Open/close Experimental Study on the Interaction of Electromagnetic Waves and Glow Plasma

  Zhang Zhitao (张芝涛) et al 2011 Plasma Sci. Technol. 13 279 Tag this article

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  An experimental system was established in order to study the interaction between electromagnetic waves, with a frequency of 300 kHz to 3 GHz, and DC glow discharge plasma. The results show that the DC glow discharge plasma affects the transmission properties of electromagnetic waves, while the waves can change both temperature and density of electrons.

• Open/close A Fusion Neutron Source Driven Sub-Critical Nuclear Energy System: A Way for Early Application of Fusion Technology

  Wu Yi-can 2001 Plasma Sci. Technol. 3 1085 Tag this article

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  This paper proposes a sub-critical nuclear energy system driven by fusion neutron source, FDS, which can be used to transmute long-lived radioactive wastes and to produce fissile nuclear fuel as a way for early application of fusion technology. The necessity and feasibility to develop that system in China are illustrated on the basis of prediction of the demand of energy source in the first half of the 21th century, the status of current fission energy supply and the progress in fusion technology in the world. The characteristics of fusion neutron driver and the potential for transmutation of long-lived nuclear wastes and breeding of fissile nuclear fuel in a blanket are analyzed. A scenario of development steps is proposed.

• Open/close A Novel Nanosecond Pulsed Power Unit for the Formation of OH in Water

  Li Shengli (李胜利) et al 2012 Plasma Sci. Technol. 14 312 Tag this article

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  A novel nanosecond pulsed power unit was developed for plasma treatment of wastewater, based on the theory of magnetic pulse compression and semiconductor opening switch (SOS). The peak value, rise time and pulse duration of the output voltage were observed to be −51 kV, 60 ns and 120 ns, respectively. The concentrations of ·OH generated by the novel nanosecond pulsed plasma power were determined using the method of high-performance liquid chromatography (HPLC). The results showed that the concentrations of ·OH increased with the increase in peak voltage, and the generation rates of ·OH were 4.1 × 10 ^-10 mol/s, 5.7 × 10 ^-10 mol/s, and 7.7 × 10 ^-10 mol/s at 30 kV, 35 kV, and 40 kV, respectively. The efficiency of OH generation was found to be independent of the input parameters for applied power, with an average value of 3.23×10 ^-12 mol/J obtained.

• Open/close Abnormal Enhancement of N₂⁺ Emission Induced by Lower Frequency in N₂ Dual-Frequency Capacitively Coupled Plasmas

  Yu Yiqing (虞一青) et al 2012 Plasma Sci. Technol. 14 222 Tag this article

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  Nitrogen dual-frequency capacitively coupled plasmas (DF-CCPs) with different frequency configurations, i.e., 60/2 MHz and 60/13.56 MHz, are investigated by means of optical emission spectroscopy (OES) and a floating double probe. The excited nitrogen molecule ion N ₂ ⁺(B) is monitored by measuring the emission intensity of the (0,0) bandhead of the first negative system (FNS) at 391.44 nm. It is shown that in the discharge with 60/13.56 MHz, the N ₂ ⁺ emission intensity decreases with the increase in pressure. In the discharge with 60/2 MHz, however, an abnormal enhancement of N ₂ ⁺ emission at higher pressure is observed when a higher power of 2 MHz is added. Variation in the ion density shows a similar dependence on the gas pressure. This indicates that in the discharge with 60/2 MHz there is a mode transition from the alpha to gamma type when a higher power of 2 MHz is added at high pressures. Combining the measurements using OES and double probe, the influence of low frequency on the discharge is investigated and the excitation route of the N ₂ ⁺(B) state in the discharge of 60/2 MHz is also discussed.

• Open/close Numerical Simulation of High-Current Vacuum Arc with Consideration of Anode Vapor

  Zhang Ling (张玲) et al 2012 Plasma Sci. Technol. 14 285 Tag this article

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  A high-current vacuum arc (HCVA) with the consideration of anode vapor is modeled and simulated. First, from the HCVA column model, the heat flux density to the anode is obtained, which is put into the anode activity model, and the parameter distributions (such as the vapor temperature and velocity) of anode vapor are obtained from the simulation results of the anode activity model. Then, by iterating and calculating the HCVA column model and anode activity model, the interaction between the HCVA column and the anode vapor is simulated and analyzed. In the simulation, the distribution of the axial magnetic field (AMF) generated by the electrode system is calculated by software ANSYS. The simulation results show that the influence of anode vapor on the parameter distributions in the arc column is significant. The simulation results are also compared with the vacuum arc photograph.

• Open/close Magnetic Configuration Effects on Fast Ion Losses Induced by Fast Ion Driven Toroidal Alfvén Eigenmodes in the Large Helical Device

  K. Ogawa et al 2012 Plasma Sci. Technol. 14 269 Tag this article

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  Beam-ion losses induced by fast-ion-driven toroidal Alfvén eigenmodes (TAE) were measured with a scintillator-based lost fast-ion probe (SLIP) in the large helical device (LHD). The SLIP gave simultaneously the energy E and the pitch angle χ = arccos(υ _///υ) distribution of the lost fast ions. The loss fluxes were investigated for three typical magnetic configurations of R _{ax_vac} = 3.60 m, 3.75 m, and 3.90 m, where R _{ax_vac} is the magnetic axis position of the vacuum field. Dominant losses induced by TAEs in these three configurations were observed in the E/χ regions of 50~190 keV/40°, 40~170 keV/25°, and 30~190 keV/30°, respectively. Lost-ion fluxes induced by TAEs depend clearly on the amplitude of TAE magnetic fluctuations, R _{ax_vac} and the toroidal field strength B _t. The increment of the loss fluxes has the dependence of ( b _TAE/ B _t) ^s . The power s increases from s = 1 to 3 with the increase of the magnetic axis position in finite beta plasmas.

• Open/close Determination of Non-Maxwellian Electron Energy Distributions in Low-Pressure Plasmas by Using the Optical Emission Spectroscopy and a Collisional-Radiative Model

  Zhu Ximing (朱悉铭) and Pu Yikang (蒲以康) 2011 Plasma Sci. Technol. 13 267 Tag this article

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  A Maxwellian electron energy distribution function (EEDF) is often assumed when using the optical emission line-ratio method to determine the electron temperature in low-temperature plasmas. However, in many cases, non-Maxwellian EEDFs can be formed due to the non-local electron heating or the inelastic-collisional energy loss processes. In this work, with a collisional-radiative model, we propose an approach to obtain the non-Maxwellian EEDF with a ‘two-temperature structure’ from the emission line-ratios of Paschen 2p levels of argon and krypton atoms. For applications of this approach in reactive gas (CF ₄, O ₂, etc) discharges that contain argon and krypton, recommendations of some specific emission line-ratios are provided, according to their sensitivities to the EEDF variation. The kinetic processes of the relevant excited atoms are also discussed in detail.