In the last 30 days

• Open/close Space-Resolved Spectrum Diagnose by Soft X-Ray Transmission Grating Spectrometer

  Shang Wanli (尚万里) et al 2011 Plasma Sci. Technol. 13 36 Tag this article

  Article References Full text PDF (4.46 MB)

  A space-resolving transmission grating spectrometer is established on the “Shenguang-III" prototype laser facility and an iterative procedure for unfolding the X-ray spectrum with spatial resolution is described. The diagnostics is applied to measure the X-ray spectrum from laser-entered gold target and the typical space-resolved spectrum is provided. The relative standard uncertainty of the X-ray spectrum from the laser-generated plasma is also determined.

• 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

  Article References Full text PDF (6.15 MB)

  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.

• Open/close Development of Nanopowder Synthesis Using Induction Plasma

  Guo Jiayin et al 2010 Plasma Sci. Technol. 12 188 Tag this article

  Article References Full text PDF (4.79 MB)

  The application of induction plasma technology developed for the synthesis of nanometric powders is summarized. A brief description of the scientific basis for the induction plasma processes is given, followed by the presentation of an induction plasma system developed by Tekna, together with various examples of the nanopowders synthesized using its facilities. The advantages of the induction plasma process over alternative techniques and its adaptability into industrial-scale operation is particularly illustrated. Some specific issues related to the nanopowder synthesis process are also discussed.

• Open/close Development of the PARASOL Code and Full Particle Simulation of Tokamak Plasma with an Open-Field SOL-Divertor Region Using PARASOL

  T. Takizuka 2011 Plasma Sci. Technol. 13 316 Tag this article

  Article References Full text PDF (1.50 MB)

  The PARASOL code and the simulation by using PARASOL are introduced briefly. The PARASOL code with particle-in-cell (PIC) method and binary collision model was developed in JAERI and JAEA. Simulations using PARASOL code were carried out in order to investigate the power and particle control with diveror system in fusion reactors. The one-dimensional (1D) version of PARASOL was adopted to investigate the Bohm criterion, the supersonic flow, the SOL heat conduction, and so on. The heat propagation due to edge localized mode (ELM) was studied with the 1D-dynamic PARASOL. The two-dimensional version of PARASOL for the whole tokamak plasma including scrape-off-layer (SOL)-divertor region was useful for simulating the SOL flow pattern, the electric field formation etc. Based on PARASOL simulation results, improved physics modeling for the fluid simulation was built up.

• 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

  Article References Full text PDF (5.68 MB)

  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 Kinetic Theories of Geodesic Acoustic Modes: Radial Structure, Linear Excitation by Energetic Particles and Nonlinear Saturation

  Qiu Zhiyong (仇志勇) et al 2011 Plasma Sci. Technol. 13 257 Tag this article

  Article References Full text PDF (1.11 MB)

  Geodesic acoustic modes (GAMs) are oscillating zonal mode structures unique to toroidal plasmas and are capable of regulating microscopic turbulence and associated transports. In this paper, three important aspects of GAM dynamics are investigated, namely (1) GAM continuous spectrum and its mode conversion to kinetic GAM (KGAM); (2) linear excitation of energetic particle induced GAM (EGAM) and its coupling to the GAM continuum, and (3) nonlinear saturation of EGAM via wave particle trapping. The analogy between the GAM-EGAM dynamics and the well known beam-plasma instability are also discussed.

• Open/close Study of Characteristics of the Radio-Frequency Sheath over a Substrate with a Circular Trench

  Dai Zhongling (戴忠玲) et al 2011 Plasma Sci. Technol. 13 50 Tag this article

  Article References Full text PDF (2.31 MB)

  Since processed substrates usually exhibit nonplanar surface structures in micro-electro-mechanical-systems (MEMS) etching, a two-dimensional (2D) fluid model is developed to simulate the characteristics of the sheath near a conductive substrate with a circular trench, which is placed in an argon discharge powered by a radio-frequency (RF) current source. The model consists of 2D time-dependent fluid equations, the Poisson equation, and a current balance equation that can self-consistently determine the instantaneous voltage on the substrate placed on a powered electrode. The effects of both the aspect ratio (depth/width) and the structure of the trench on the characteristics of the sheath are simulated. The time-averaged potential and electric field in the sheath are calculated and compared for different discharge parameters. The results show that the radial sheath profile is not uniform and always tends to adapt to the contour of the substrate, which is believed to be the moulding effect. Affected by the structure of the substrate surface, the potential and electric field near the inner and outer sidewalls of the trench exhibit obvious non-uniformity, which will inevitably lead to non-uniformity in etching, such as notching. Furthermore, with a fixed amplitude of the RF current source, the potential drops and the sheath thickness decrease with an increase in aspect ratio.

• Open/close Thermo-Mechanical Analyses of the High Heat Flux Component for ITER Dual Functional Lithium Lead Test Blanket Module

  Chen Hongli and Bai Yunqing 2009 Plasma Sci. Technol. 11 236 Tag this article

  Article References Full text PDF (671 KB)

  The finite element code ANSYS is used to calculate the temperature and stress distributions for the first wall of DFLL-TBM (dual functional lithium lead-test blanket module), for testing in ITER. Preliminary analyses indicate that not only the low temperature design rules, the well-known 3 S _m rules, are satisfied for the first wall, but the additional high temperature structural design criteria for the creep damage limits and creep-ratcheting limits are met as well.

• Open/close An Experimental Platform for the Study on Magnetic Reconnection in Laboratory Plasmas

  Zhang Shoubiao (张寿彪) et al 2011 Plasma Sci. Technol. 13 286 Tag this article

  Article References Full text PDF (695 KB)

  In order to investigate electron dynamics near the electron diffusion region in magnetic reconnection process, an upgrade in the linear magnetized plasma (LMP) device is accomplished at the University of Science and Technology of China. Radio frequency (RF) helicon discharge is used to generate a quasi-stationary plasma, and a time-dependent magnetic field is applied to the plasma, which exhibits an X-type neutral point in vacuum. A two-dimensional sophisticated mobile platform is built up, providing a high spatial resolution, below 0.5 mm, for the diagnostics.

• Open/close Improvement of Plasma Performance Using Carbon Pellet Injection in Large Helical Device

  Shigeru Morita et al 2011 Plasma Sci. Technol. 13 290 Tag this article

  Article References Full text PDF (3.24 MB)

  A cylindrical carbon pellet with a size of 1.2 ^L × 1.2 mm to 1.8 ^L × 1.8 mm and a velocity of 100 m/s to 300 m/s was injected into large helical device (LHD) for an efficient fueling based on its deeper deposition instead of hydrogen gas puffing and ice pellet injection. Electron density increment of Δ n _e = 10 ¹⁴ cm ⁻³ is successfully obtained by single carbon pellet injection without plasma collapse. Typical density and temperature of the ablation plasma of the carbon pellet, e.g., 6.5 × 10 ¹⁶ cm ⁻³ and 2.5 eV for CII, are examined respectively by spectroscopic method. A confinement improvement up to 50% compared to ISS-95 stellarator scaling is clearly observed in a relatively low-density regime of n _e = 2×10 ¹³ cm ⁻³ to 4×10 ¹³ cm ⁻³, and high ion temperature T _i(0) of about 6 keV is also observed with an internal transport barrier at n _e = 1.2×10 ¹³ cm ⁻³. In particular, the improvement in the ion temperature largely exceeds that observed in hydrogen gas-puffed discharges, which typically ranges below 3 keV.