利用超声氦束测量边界等离子体参数

The distribution and performance of edge plasma are the key problems in various advanced running modes of nuclear fusion. Therefore, the parameters of the edge plasma is of particular importance in understanding various high constrained behaviors and mechanics during fusion experiment. By using a Laval nozzle, designed on aerodynamic principle, which creates supersonic helium beam with very small diffusive angle (at the velocity of 2~3km/s), to measure the ne(r) and Te(r) in the edge with the ratio value of two pair of helium spectrum lines, we make the measurement range be much wider (5 eV < Te < 300 eV and radial distance being about 10 cm). This has become a powerful means in thorough physical investigation of fusion research and also a original creation in plasma diagnoses. According to the plan of this fund, we have successfully developed and designed a Laval nozzle used in measuring the parameters of edge plasma; developed a multi-channel amplifier and the corresponding optical system for the experiment; programmed the code by using the radiate strength of hedium spectrum lines to obtain the temperature and density of the edge plasma; and measured the electron temperature in the edge. During the implementation of this research, we adjusted and extended the oringial plan according to the development of international tokamak experiment by applying the Laval nozzle to load fuel into tokamak and achieved good experimental results: the maximum density reached 6.5×1019m-3 when loading hedium at high speed and 5.5×1019m-3 when loading deuterium at high speed, which extended the operation space of plasma on HT-7 tokamak greatly. The experimental data demonstrated that the efficiency by the usage of Laval nozzle to load the fuel was 30% higher than that by common loading method, and this technique can be used for steady fuel loading with high-effficiency in future experiment on large-scale superconduction equipment. As this fuel loading method is peculiar and efficient, this fuel loading technique with Laval nozzle and the corresponding experimental results have been drawn forth great attention in the research and applied in the experiment by abroad experts of this field. Totally three research papers have been published for this fund, one was on international conferences, and two were in international journals.

近年来，国际受控界已经认识到边界等离子体的高约束行为起到至关重要的作用，边界等离子体参数分布的测量是这一研究的关键。本项研究利用拉瓦尔喷嘴产生的超声速氦束，结合吸收比较法求出边界的电子密度分布和温度分布。该方法不受强磁场影响，测量精度高，还具有很高的时空分辨率。该方法的成功使用能为磁约束聚变研究提供一个全新的诊断技术。