Nuclear Fusion and Plasma Physics

Schemes for the HL-2A tokamak modification

LIU De-quan, ZHANG Jin-hua, LI Fang-zhu, LI Qiang, YAN Long-wen, PAN Yu-dong, RAN Hong, LI Guang-sheng, LIU Yong

2006, 26(4): 257-262.

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Three schemes for HL-2A tokamak modification have been proposed to increase plasma parameters and obtain optimal plasma configuration. They are a local modification of adjusting the poloidal coils in vacuum vessel with remaining of vacuum vessel, a middle scale modification of rearranging poloidal coils with remaining of vacuum vessel and an enormous one of redesigning vacuum vessel and poloidal coils. Three schemes have been analyzed and compared, and the third one is optimal.

Analysis of thermal stress for a grid of 60kV-55A-2s ion source

ZHOU Gui-qing, JIANG Shao-feng, LEI Guang-jiu, ZHOU Cai-pin

2006, 26(4): 263-267.

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Analysis of thermal stress for a grid of ion source with 60kV, 55A and 2s is carried out using finite element method. Numerical simulation for transient temperature indicates that it takes 6s to make thermal balance, and the maximum temperature is less than 100℃ at 2s. The results indicate no melt and no plastic deformation on the grid under a heat loads of 2.0MW•m^-2 with cooling water velocity of 10m•s^-1. The most dangerous point and the maximum displacement of the grid are also shown in the paper.

Study of ion temperature gradient driven instability from reduced Braginskii equations

JIANG Hai-bin，WANG Ai-ke

2006, 26(4): 268-271.

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A new dispersion relation for the ion temperature gradient (ITG) driven instability in toroidal plasma is derived from the reduced Braginskii equations. It includes the effects of both the safety factor q and the adiabatic electron temperature gradient . The present model reproduces the basic properties of ITG instability obtained by previous works. On the other hand, it is found numerically that the safety factor q enhances the ITG instabilities while the quantity reduces them .

The calculation and simulation of the ECRH HV power supply for the HL-2A tokamak

MAO Xiao-hui，LI Qing，XUAN Wei-min，YAO Lie-ying

2006, 26(4): 272-276.

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In order to satisfy the requirement of ECRH, the ECRH HV power supply (ECHV-HVPS) on the base of high voltage pulse modulation has been designed. The filter inductance in the ECHV-HVPS is much smaller than the voltage regulation power supply. Modulations are adopted in the power supply, so the short time of the leading edge and lagging edge of the pulse is achieved. The main circuit of the ECHV-HVPS is showed. The equivalent resistance and the transient response of the PS are calculated and analyzed using MATLAB, and experiment results are given.

Discharge simulation for EAST and analysis of flux consumption

NIU Xin-ping, WU Bin

2006, 26(4): 277-282.

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A simulation code is used to simulate the whole tokamak discharge process for parameters relevant to EAST. This simulation takes into account of the plasma bootstrap current, ion cyclotron resonance heating and fast wave current drive. A D-shape plasma equilibrium with peak density of 1.2×10²⁰m^-3, T_e=4.5keV, T_i=3.8keV is got. According to the simulation results, we make a analysis of flux consumption for EAST, and study influences of the plasma current ramp up time and the effective charge.

The effects of Compton scattering on the light field and electron density profile in the laser plasma

HAO Dong-shan, YU Ding-chen

2006, 26(4): 282-287.

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Under the action of the femto-second laser, when the multi-photon nonlinear Compton scattering takes place in the linear plasma, the effects of the femto-second coupling laser field formed by the scattering laser and incident laser on the light field and electron density profile in the linear plasma have been studied using the model of the inelastic collision between the electron and multi-photon group and the model of the cold plasma. The results show that under the action of the ponderomotive force of the coupling laser, there are a larger divergence of the density profile of the electron and ion in the laser-plasma than that without Compton scattering， the faster change of the electron density than the ion density，and the stronger electrostatic field than that without Compton scattering. Even if the coupling laser field is the very small and weak，there still are the relativistic effects of the electron motion and the electrostatic field.

Theoretical study of mean opacity of Au-Gd mixture

YAN An-ying, JIANG Ming

2006, 26(4): 288-293.

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The screened hydrogenic model with l splitting is proposed to calculate the Rosseland mean opacities for Au-Gd mixture at the temperature T=250eV and the density ρ=1g•cm^-3. The results are in good agreement with experiment measurements and other theoretical calculations.

Development of remote experiment data access and process system for the HL-2A tokamak

LI Yong-ge, CHEN Liao-yuan, PAN Li, PAN Wei, LIAO Min

2006, 26(4): 293-297.

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According to the characteristics of HL-2A DAS data, a remote data access and process system is developed on an advanced N-layer architecture. The system has substantial functions for remote signal processing, computing and information querying. It also realizes remote transmission of the data, which is only requisitioned by a user. Some simple examples are introduced about Web and Windows client-side applications which are based on the system.

The application of wavelet in processing the control signal of fast control power supply in EAST tokamak

LU Song-sheng, LIU Zheng-zhi

2006, 26(4): 297-301.

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The control signal of fast control power supply (FCPS) in EAST tokamak is decomposed using wavelet multi-resolution. The control signal of FCPS satisfied the demand is obtained, and verified by the simulation and test. Results show that the effect using wavelet is better than other methods.

The control survey of key parts assembly on EAST tokamak

ZHAO Qing-rong, WU Song-tao

2006, 26(4): 302-306.

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The technology based on the precise engineering survey has been adopted to control the key parts’ assembly position of EAST tokamak. The establishment of the survey control networks is also described. With application of the appropriate survey plans, the key parts assembly position design precision in the EAST device has been ensured.

High signal-to-noise ratio Langmuir probe system

LI Ya-lei, DENG Xin-lv, XU Jun, DING Wan-yu

2006, 26(4): 306-309.

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A new Langmuir probe system based on integrator is introduced. New features of the system include: the integrator network to implement the process of analog-to-digital conversion and to provide effective noise suppression; data processing card to communicate with the host computer. It gives a noise elimination method which increased signal-to-noise ratio dramatically. Successful operation of the system has been demonstrated in the electrically noisy environment of an ECR plasma source.

The stimulated Raman scattering from interaction of 351nm laser light with hohlraum

Wang-chuan-ke, KUANG Long-yu, WANG Zhe-bin, LIU Shen-ye, LI Wen-hong, LI San-wei, JIANG Xiao-hua

2006, 26(4): 310-314.

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An experimental study of laser-plasma interaction in hohlraum by laser with 351nm wavelength and 2ns pulse at SGII facility is reported in this paper. The angular distribution of stimulated Raman scattering (SRS) energy has been measured. In the same conditions of laser pulse width and hohlraum dimension, the SRS energy from slot hohlraum is higher than that from hohlraum, and the energy from small hohlraum is higher than that from standard hohlraum. The SRS energy from interaction of 2ns laser with hohlraum is weaker than that of 1ns laser with hohlraum due to decrease of laser power density. The experiments show that the size of standard hohlraum is unsuitable for 2ns laser-produced plasma.

Development of SWITRIM code and its applications

DENG Bai-quan, HUANG Jin-hua, FENG Kai-ming, CHEN Zhi, YUAN Tao

2006, 26(4): 314-317.

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Numerical simulation code package SWITRIM has been developed to calculate the tritium inventory distribution and its time evolution in all subsystems of FEB reactor. The applications in recent 5 years indicate that it is reasonable and reliable. The new phenomenon of “tritium well depth and tritium well time” during the fusion reactor start-up phase is studied using the SWITRIM code package. The combination of the SWITRIM code package, user’s guide and the latest example are briefly introduced.

Application researches on doped graphites as plasma facing materials

LIU Zhan-jun1，2, GUO Quan-gui1, SONG Jin-ren1, LIU Lang1, CHEN Jun-ling3, LI Jia

2006, 26(4): 318-323.

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The recrystallized graphites were prepared with calcined coke filler, coal-tar pitch binder and additives of B₄C、Si、Ti by the hot-pressing in order to investigate the thermo-mechanical properties and microstructure of the recrystallized graphites. Radiation damages of the recrystallized graphites by ion bombardment in HT-7 fusion environment were also studied. The experimental results showed that the recrystallized graphites doped 10%B₄C exhibited higher bending strength, up to 104Mpa, but lower thermal conductivity; on the contrary, the recrystallized graphites doped Si and Ti exhibited higher thermal conductivity but lower bending strength. Compared with pure graphite, the erosion-resistant of the recrystallized graphites was improved obviously. The thickness of the gradient SiC coating of BSTDG was thinned from 40～50μm to 5μm, and the coating flaked off partially after irradiation in HT-7 tokamak.

AC pin-to-plate atmospheric glow discharge in air

ZHANG Yu-tao, MA Teng-cai, REN Chun-sheng, QI Bing, MIAO Shu-yi, WANG De-zhen, WANG You-nian

2006, 26(4): 323-327.

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Atmospheric glow discharge in air is produced difficultly due to that the discharge is transited easily to spark discharge. By means of resistance and capacitance coupled negative feedback method to control the plasma discharge development process and prevent the transition from glow discharge to spark discharge in a pin-to-plate static air plasma generator, a stable alternative current atmospheric glow discharge is produced successfully. The effects of voltage and electrode gap on discharge is studied.

Methane coupling to C₂ hydrocarbons using glow discharge plasma

WANG Da-wang，MA Teng-cai

2006, 26(4): 327-330.

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At normal temperature and pressure, glow discharge plasma was used as a new method for the coupling of methane to hydrocarbons by a new type plasma reactor with rotary electrode. On the experimental scale, the results showed that C₂H₂ is more than 80% in C₂ hydrocarbons formation and energy efficiency is 5.6% to 11.2%. With increasing of the amount of hydrogen, the CH₄ conversion and the yield of C₂ hydrocarbons were increased. As the energy density increased from 500 to 2200 kJ•mol⁻¹, CH4 conversion increased linearly and C₂yield changes with a peak-shape curve.

Nuclear Fusion and Plasma Physics Vol.26 ( 2006 )

2006, 26(4): 331-337.

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