Table of Content

15 June 2007, Volume 27 Issue 2

Previous Issue    Next Issue

Research Report

Experimental investigation of electrostatic fluctuation and related transport at the edge of HL-2A plasma

CHENG Jun, YAN Long-wen, HONG Wen-yu, QIAN Jun

2007, 27(2):  81-86. 

Asbtract ( )   PDF (1182KB) ( )  

References | Related Articles | Metrics

The electrostatic fluctuation and related transport at the edge of HL-2A plasma have been investigated using the parameters such as electron temperature, electron density, plasma potential, their fluctuations, particle flux and energy flux, which are simultaneously measured in a single steady shot by means of fast reciprocating probe system. Analyzed fluctuation features including the Boltzmann relationship of edge parameters, the radial electron-field shearing induced by the gradients of plasma potential, and the influence of fluctuations on edge confinement are given.

Suppression of Rayleigh-Taylor instability by gyroviscosity and sheared axial flow in imploding plasma pinches

HUANG Lin, JIAN Guang-de, QIU Xiao-ming

2007, 27(2):  87-94. 

Asbtract ( )   PDF (728KB) ( )  

References | Related Articles | Metrics

The synergistic stabilizing effect of gyroviscosity and sheared axial flow on the Rayleigh-Taylor instability in Z-pinch implosions is studied by means of the incompressible viscid magneto-hydrodynamic equations. The gyroviscosity (or finite Larmor radius) effects are introduced in the momentum equation through an anisotropic ion stress tensor. Dispersion relation with the effect of a density discontinuity is derived. The results indicate that the short-wavelength modes of the Rayleigh-Taylor instability are easily stabilized by the gyroviscosity effects. The long wavelength modes are stabilized by the sufficient sheared axial flow. However, the synergistic effects of the finite Larmor radius and sheared axial flow can heavily mitigate the Rayleigh-Taylor instability. This synergistic effect can compress the Rayleigh-Taylor instability to a narrow wave number region. Even with a sufficient gyroviscosity and large enough flow velocity, the synergistic effect can completely suppressed the Rayleigh-Taylor instability in whole wave number region.

Heat load of EAST PF coils during plasma discharge

TAN Yun-fei, WENG Pei-de, SUN Wei-wen, LIU Fang, LI Shao-lei

2007, 27(2):  95-100. 

Asbtract ( )   PDF (952KB) ( )  

References | Related Articles | Metrics

From magnetic fields in PF coils of EAST expressed as elliptic integrals, the heat load of PF coils during plasma discharge is determined. The maximum temperature rise of these coils is also estimated from the thermo-hydraulic condition of the magnet operation.

Study of 16kA high temperature superconducting current leads used in EAST’s toroidal field magnets system

ZHU Yin-feng, WU Song-tao, BI Yan-fang, MA Deng-kui, WU Yu

2007, 27(2):  101-105. 

Asbtract ( )   PDF (1083KB) ( )  

References | Related Articles | Metrics

In EAST (experimental advanced superconducting tokamak), power supplies are connected to suerconducting magnets by high temperature superconducting current leads(HTSCL). In order to reduce the costs in the course of experiments, hybrid type of current leads were selected．Two toroidal field HTSCL were tested, The results can satisfy the design requirement．

Calculation of atomic data for plasmas using a relativistic screened hydrogenic model

DUAN Yao-yong, GUO Yong-hui, KUAI Bin

2007, 27(2):  106-112. 

Asbtract ( )   PDF (1130KB) ( )  

References | Related Articles | Metrics

A test-potential method and a mean radius-screened charge loop iteration method are utilized to find the screened charges in the relativistic and the non-relativistic screened hydrogenic models. The screened charges obtained by the above two methods show that the mean radius-screened charge loop iteration method exhibits advantages over the test-potential method both in solving efficiency and solution precision. The comparisons of electron ionization energies, ionic total energies and electron transition energies calculated respectively by More, Faussurier and the relativistic screened hydrogenic models, have been performed and the precisions of these physical quantities verify the preponderance of the relativistic screened model based on the analytical potentials.

Variation of frequency-dependent opacity with temperature for Sn plasma

YAN An-ying1, BAO Xing-ming2, JIANG Ming1

2007, 27(2):  113-116. 

Asbtract ( )   PDF (764KB) ( )  

References | Related Articles | Metrics

By SHML model, the frequency-dependent opacity and the Rosseland mean opacity for Sn plasma at high temperature (150eV, 200eV, 250eV, 300eV, 400eV) and density (ρ=1g•cm^-3) are calculated. The relationship between the absorption peaks (the opacity peaks) of curve of frequency-dependent opacity and the transitions are explained. The results are in good agreement with theoretical calculations using DCA/UTA and STA model.

Application of hybrid tomography diagnosis on the HL-2A tokamak

DENG Wei，DONG Yun-bo，CUI Zheng-ying，FU Bing-zhong

2007, 27(2):  117-122. 

Asbtract ( )   PDF (1227KB) ( )  

References | Related Articles | Metrics

Results of the two-dimensional reconstructed distribution of soft X-ray emission on the HL-2A tokamak are presented. Improvement of soft X-ray cameras and development of tomography software have been given in details with visual studies of soft X-ray emission on the HL-2A tokamak. Several algorithms are employed to get detailed images while keeping least guiding assumptions. Recently a 2D peeling away algorithm for tomography reconstruction of the HL-2A soft X-ray data is applied successfully. It helps the research of impurity injection and double sawtooth crash.

Calculation of ECRH ray tracing and power deposition on HL-2A tokamak

SONG Shao-dong, LIU Yong, ZHANG Jin-hua, HE Hong-da, RAO Jun

2007, 27(2):  123-126. 

Asbtract ( )   PDF (946KB) ( )  

References | Related Articles | Metrics

The interaction between ECW and HL-2A plasma has been simulated using TORAY. The effects of plasma and wave parameters on ECRH ray trace, power deposition and current drive has been investigated. According to the calculation, when the linear-averaged density is 3.0×10¹³cm^-3 and the central temperature is 1.19keV, the single-pass absorption efficiency is 99.29%, and the maximum current drive efficiency is 0.005×10²⁰A•W^-1•m^-2.

A high performance computer system for HL-2A tokamak experiment

CHEN Liao-yuan, PAN Wei, ZHANG Jin-hua, LIAO Min, LI Yong-ge, LUO Cui-wen, WANG Xiu-hui

2007, 27(2):  127-130. 

Asbtract ( )   PDF (668KB) ( )  

References | Related Articles | Metrics

A high performance computer system with total 130 CPU, for HL-2A experiment has a peak performance of 768 GFLOPS and it is easy to be managed and expanded. With the system built, some research on optimization of programm performance and application on HL-2A experiment have been carried out. Some progresses have been made.

Preliminary design of a pellet injector based on a cycle refrigerator on HL-2A tokamak

XU Hong-bing, LIU De-quan, XIAO Zheng-gui, ZHU Gen-liang, WANG Ming-jian

2007, 27(2):  131-136. 

Asbtract ( )   PDF (913KB) ( )  

References | Related Articles | Metrics

A new flexible and efficient pellet injector with more barrels is designed for the HL-2A core plasma fueling at higher plasma parameters. The design of the 25-barrel pellet injector based on the G-M cycle refrigerator is introduced in this paper. Components, engineering parameters and structure design are all described. The thermal stresses of main parts are calculated in detail using a 3-dimensional heat transport analysis code. Temperature gradient along the barrel and pellet injection modes are also discussed.

Study of the property of EAST composite insulators with finite element analysis

ZHANG Yuan-bin1， PAN Wan-jiang2，XI Wei-bin2，SHENG Dao-lin2

2007, 27(2):  137-140. 

Asbtract ( )   PDF (763KB) ( )  

References | Related Articles | Metrics

The property of helium leak tight composite insulators in EAST magnet system is analyzed by finite element method. Calculation results show that the composite insulators can endure 15kV high voltage, thermal tensors have main influence on insulators and the insulators present good cryogenic performance.

Calculations of helium pressure drop in the current lead of EAST superconducting magnet

KANG Zhi-cheng, LAN Jian-she, DING Li-ren

2007, 27(2):  141-144. 

Asbtract ( )   PDF (764KB) ( )  

References | Related Articles | Metrics

Helium pressure drop in the current lead of EAST superconducting magnet was calculated using FEA code. The helium model was simplified and divided into a few of segments in calculation, and every two conjoint segments were coupled by the flux boundary condition and pressure boundary condition. Some results obtained were given.

Design of diamagnetic loop on EAST superconducting tokamak

XI Wei-bin, SHEN Biao, QIAN Jin-ping, WU Song-tao, WAN Bao-nan

2007, 27(2):  145-149. 

Asbtract ( )   PDF (1021KB) ( )  

References | Related Articles | Metrics

The design of EAST diamagnetic measurement system including diamagnetic loop and compensation loop has been given. The advantage of this method is that, the compensation loop is applied for eliminating the change of toroidal flux produced by the toroidal coils and the adjustable structure can be used to decrease the error signals come from the poloidal field. On the other hand, the effect of the material and structure on the diamagnetic loop is detailedly checked during engineering design. Error analysis of the measurement system is given.

Reaction apparatus of plasma polymerization and applications

WANG Hong, LI Lai-feng, HUANG Chuan-jun, SHI Dong-liu

2007, 27(2):  150-155. 

Asbtract ( )   PDF (1240KB) ( )  

References | Related Articles | Metrics

The history and characterizations of plasma polymerization technique are introduced in brief. The reaction apparatus of plasma polymerization are introduced in details. Research on the surface modification processes for various nano-materials such as Al₂O₃, ZnO, carbon nano-tube, carbon fiber, is also discussed.

Diagnosis of radio frequency induced plasma with Langmiur probe and spectrum

ZHANG Jian, REN Chun-sheng, QI Xue-lian, WANG You-nian

2007, 27(2):  156-162. 

Asbtract ( )   PDF (832KB) ( )  

References | Related Articles | Metrics

In argon plasma induced by radio frequency of 13.56MHz, radial and axial profiles of plasma parameters have been measured versus pressure by Langmiur probe and axial intensity of Ar spectrum at 750.3nm has been obtained versus pressure using the emission spectrum. The results show that the same diversification appears in both data. Axial intensity of Ar⁺ spectrum at 434.8nm was measured with the pressure, and the ratios of 434.8nm Ar⁺ spectrum intensity to the 430.0nm Ar’s were obtained with pressure in three axial positions. The results indicate that a high density uniform and stable plasma has formed in the middle and at the top of the discharge chamber, its density descends at the target and the plasma density decreases slowly below the middle of the chamber. The plasma parameters change slightly in radial area within 6~7cm, a radially uniform and stable plasma also occurs.

Deposition and erosion study on amorphous hydrocarbon films by in situ ellipsometry

SUN Chao, XU Jun, MA Teng-cai

2007, 27(2):  163-167. 

Asbtract ( )   PDF (609KB) ( )  

References | Related Articles | Metrics

The deposition and erosion of amorphous hydrocarbon films by a methane plasma with O₂, H₂, H₂/N₂(30% N₂) and CH₄/N₂ (30% N₂) are investigated by in situ ellipsometry. RF bias voltage could make effects on the optical properties of amorphous hydrocarbon films, actually the refractive index and extinction coefficient increase with the increase of bias voltage. The deposition rate of methane plasmas increases when the bias voltage increases from floating potential to 100V, then it decreases from 100V to 200V. Erosion is most effective in pure O₂ plasma. For the erosion experiments using CH₄/N₂ mixtures, transition from deposition to erosion was observed when bias voltage increased from zero to 300V.

Study of the power variation of the gliding arc driven by the magnetic field

LI Hui, TAO Xiao-ping, WANG Chuan-bing

2007, 27(2):  168-171. 

Asbtract ( )   PDF (596KB) ( )  

References | Related Articles | Metrics

The power variation of gliding arc driven by the magnetic field with the highest value 6040Gs in the parallel electrodes 25mm apart with 40mm length is discussed.The phase of gliding arc plasma is also analyzed. When arc moves on the parallel part of electrodes, the arc power is drastically fluctuated at 0.65kW. When arc is moving to the top of electrodes, the arc power increases rapidly from 0.65kW to 2.0kW. In generally, the arc power increases in one cycle of arc discharge and the arc plasma continuously obtains energy form power supply to maintain the equilibrium phase of arc plasma. According to the theory of Ozlem Mutaf-Yardimici, the phase of the gliding arc plasma is in equilibrium.

Diagnostics of plasma jet in AC glow discharge by concentration modulation spectroscopy

SUN Dian-ping, ZHU Y, LIU Yu-Tan, CHEN Yang-Qin

2007, 27(2):  172-176. 

Asbtract ( )   PDF (737KB) ( )  

References | Related Articles | Metrics

Nitrogen plasma jet in the AC discharge is studied by means of the concentration modulation spectroscopy. Nitrogen ions were generated in pulse mode when the discharge voltage was higher than 9.6 kV (peak-to-peak), and the ions pulse arose only in every negative cycle of the discharge, meanwhile an opposite peak appeared in the discharge current. This peak was formed by the inertia movement of ejecting nitrogen ion in jet. Additionally, the intensity of the ions was found to be proportional to the area of this opposite peak. This phenomenon was interpreted by a proposed theoretical model based on the detected 1f/2f data by concentration modulation spectroscopy.