用远红外HCN激光干涉仪测量等离子体电子密度

在大多数托克马克上，远红外激光干涉仪是等离子体诊断中的一种重要的装置。本文介绍了用远红外ＨＣＮ激光干涉仪测量等离子体电子密度的原理和激光干涉仪结构，并给了了首次在我国第一以大型超导托克马克ＨＴ－７装置上测到的中心弦等离子体电子平均密度。     

The Experiment of Modulated Toroidal Current on HT-7 and HT-6M Tokamak

The Experiments of Modulated Toroidal Current were done on the HT-6M tokamak and HT-7 superconducting tokamak. The toroidal current was modulated by programming the Ohmic heating field. Modulation of the plasma current has been used successfully to suppress MHD activity in discharges near the density limit where large MHD m = 2 tearing modes were suppressed by sufficiently large plasma current oscillations. The improved Ohmic confinement phase was observed during modulating toroidal current (MTC) on the Hefei Tokamak-6M (HT-6M) and Hefei superconducting Tokamak-7 (HT-7). A toroidal frequency-modulated current, induced by a modulated loop voltage, was added on the plasma equilibrium current. The ratio of A.C. amplitude of plasma current to the main plasma current △Ip/Ip is about 12% ～ 30%. The different formats of the frequency-modulated toroidal current were compared.     

Density Modulation Experiments to Determine Particle Transport Coefficients on HT-7 Tokamak

The particle diffusion coefficient and the convection velocity were studied based on the density modulation using D2 gas puffing on the HT-7 tokamak. The density was measured by a five-channel FIR interferometer. The density modulation amplitude was 10% of the central chord averaged background density and the modulation frequency was 10 Hz in the experiments. The particle diffusion coefficient （D） and the convection velocity （V） were obtained for different background plasmas with the central chord averaged density 〈ne〉 = 1.5×10^19m^-3 and 3.0×10^19 m^-3 respectively. It was observed that the influence of density modulation on the main plasma parameters was very weak. This technology is expected to be useful for the analysis of LHW and IBW heated plasmas on HT-7 tokamak in the near future.     

太赫兹连续波DCN激光器的实验研究

介绍了运行在1.54THz(195μm)和1.58THz(190μm)的波导型辉光放电激励的大功率连续波DCN激光器的开发和研制工作.该激光器的谐振腔长3.4m,放电长度3m,谐振腔由耐热玻璃制成,直径54mm.谐振腔一端为平面反射镜,一端为金属栅网.工作气体为N2,CD4和He(或D2)的混合气体,在1.54THz的连续激光输出功率大于0.2W.实验中对放电电流、激光管温度、气压等参数进行了优化,研究了EH11模DCN激光在自由空间的传输特性.研究表明,利用新的N2,CD4和D2混合气体的太赫兹DCN激光器可以得到稳定连续的高功率放电.光束传输远场满足高斯分布(z>4m),对各种参数进行优化后,190μm和195μm窗口处输出EH11模功率分别为0.15W和0.16W,可以满足超导托卡马克连续运行的干涉测量的需要.     

基于Linux的数据服务器在核能工程中的应用

介绍在核能科学领域,基于Linux操作系统的稳定的数据服务器的搭建过程.通过安装和配置Linux系统的Vsftpd、 Apache HTTP以及OpenSSH服务软件包完成对服务器FTP服务、Web服务和SSH服务的搭建,并对过程中需要注意的诸如主机访问控制、不同操作系统的字符集编码转化等问题进行分析和解决.     

Multi-channel FIR Interferometer for Electron Density Measurement on HT-7 Superconducting Tokamak

1. IntroductionHigh-density plasma are of interest in thermonuclear fusion research. Fusion plasma density canbe measured by FIR laser and submillimeter waveinterferometer [l]. Plasma are transparent as longas the plasma frequency wp is smaller than the frequency w of the probe wave. The index of refractionof a medium is easily measurable by using electromagnetic waves for which the medium is transparent [l,21. The values of tile index of refraction, po,correspond to a polarized wave with it…     

Spontaneous current relaxation in NBI heated plasmas on EAST

We report on current profile evolution in EAST NBI driven plasmas where two neutral beams are injected,one during the current ramp phase and the second during flattop.At the end of the current ramp phase,it is found that a flat q profile with q0?~?1 is achieved with low magnetic shear in the core.It is observed that plasma current and density both relax much faster than resistive time,even in the absence of sawtooth activity when H–L transition occurs.Density fluctuations associated with magnetic perturbations(3/2) as a precursor to the H–L transition are observed.It is likely that these modes play a role in fast current transport.     

HCN Laser Interferometer on the EAST Superconducting Tokamak

A single-channel far-infrared （FIR） laser interferometer was developed to measure the line averaged electron density on the EAST tokamak. The structure of the single-channel FIR laser interferometer is described in detail. The evolution of density sawtooth oscillation was measured by means the FIR laser interferometer, and was identified by electron cyclotron emission （ECE） signals and soft X-ray intensity. The discharges with and without sawtooth were compared with each other in the Hugill diagram.     

石英晶体寻常光折射率的确认

用HCN激光干涉仪,通过测量位相差的方法,简单地确认了激光波长为336.5578μm的石英晶体寻常光折射率n_0。表明n_0=2.1076比n_0=2.113更符合实验结果。     

Sawtooth Control Experiments on HT-7 and EAST Tokamak

Sawtooth control experiments were performed on HT-7 with a limiter configuration and on the Experimental Advanced Superconducting Tokamak (EAST) with a double null con-figuration. The sawtooth period can be modified by lower hybrid wave (LHW) and ion cyclotron resonance frequency (ICRF). Different sawtooth behavior was observed with the same plasma density, LHW power but different plasma currents on HT-7. There was a dwell time between LHW added and the sawtooth stabilization on HT-7 while the sawtooth stabilization immediately happened when LHW power was injected on EAST. The possible mechanism of the sawtooth control is discussed in this paper. All the experimental results have proved that power deposition of the radio frequency (RF) should be the key factor for sawtooth control.