Development of Toroidal Machine for Fundamental Research of Advanced Tokamak

采用脉冲宽度为40kHz的IGBT逆变电源，实现了等离子体电流为600A、平顶频率为6ms、60Hz、几乎无停留时间的完全连续托卡马克放电。在稳态0.1T的环向磁场下，等离子体的电子密度为-1 × 10^<18>m^<-3>，电子温度< 15eV。回路电压在10V左右。单极长时间高占空托卡马克放电的实现单极放电电流高达950A，平顶时间为6ms，实现了高重复、高占空达50%、持续时间为1分钟的托卡马克放电。在真空室壁面氢气循环过程中，发现了边缘氢气压力的一个非常有趣的时间演化规律。目前正在发展粒子平衡的数值模拟，以了解氢循环的几个基本过程。在环形直流放电中，制备了B场与靶板连接长度为16cm的LaB_6阴极高密度环形等离子体。碳棒通过许多LaB_6珠来加热LaB_6阴极。这种长阴极组件设置在环面上，与环面磁场的掠角为5.5‰。放电发生在与磁场垂直平行的阴极和阳极之间。静态垂直磁场与环形磁场相结合，使得真空室底部的靶板连接长度较长。在B_t=0.086T,B_v=4.5*10^<-4>T,P_<Ar>=5*10^<-4>Torr, I_<放电>=2A的放电条件下，产生了等离子体密度接近10^<19>m^<-3>的氩等离子体。该研究为环形导流器模拟器的构建奠定了基础。

Realization of Fully Continuous AC Tokamak OperationFully continuous tokamak discharges have been realized with the plasma current of 600A,the flat top of 6ms, 60Hz and almost no dwell time by employing IGBT invertor power supply with 40kHz pulse width modulation. Under the toroidal magnetic field of 0.1T in steady state, we have the plasma with the electron density of -1*10^<18>m^<-3>, the electron temperature of < 15eV.The loop voltage is around 10V.Realization of Mono-pole Long Duration Tokamak Discharge with High DutyThe high repetition tokamak discharge with the high duty up to 50% and the duration of 1 minute has been realized for mono-pole discharge current of up to 950A with the flat top of 6ms. A very interesting time evolution of hydrogen gas pressure at the edge has been found in terms of nydrogen recycling on the wall of vacuum chamber. The numerical modelling on particle balance is now being developed to know the several elementary processes on hydrogen recycling.Generation of High Density Toroidal Plasma with Long Connection Length of B Field to the Target PlateA LaB_6 cathode with the length of 16cm has been developed for the toroidal DC discharge. A carbon rod passing through many LaB_6 beads is employed to heat the LaB_6 catohde. Such a long cathode assembly is set in the torus to have a grazing angle of 5.5ﾟ with the toroidal magnetic field. The discharge takes place between the cathode and the anode set vertical pararell to the magnetic field. A seady state vertical magnetic field combined with the toroidal field make the long connection length to the target plate located at the bottom of vacuum chamber. Argon plasma with the plasma density close to 10^<19>m^<-3> has been generated under the following discharge condition : B_t=0.086T,B_v=4.5*10^<-4>T,P_<Ar>=5*10^<-4>Torr and I_<discharge>=2A.This research becomes the basis for the construction of Toroidal Divertor Simulator.