This paper presents an experimental characterization of the local plasma parameters in the COMPASS open divertor in deuterium, L-mode plasmas by means of Langmuir probes during neutral beam injection (NBI) heating. The effect of NBI heating of the core plasma on the local divertor plasma parameters is investigated under different plasma configurations and different directions of the magnetic field and plasma current for different line-averaged electron densities. At low line-averaged densities below 6 10¹⁹ m^-3, a low NBI heating power level does not lead to any significant changes in the plasma parameters in the divertor region. It is also found that for a reversed magnetic field the influence of NBI in the divertor is stronger at higher line-averaged electron density and plasma current. In the divertor, the impact of the NBI heating is more pronounced at high delivered powers (above P _NBI = 320 kW) and line-averaged densities (above 7 10¹⁹ m^-3). The electron temperature and the floating potential at the outer target increases respectively with 10–50% and 100%, while the plasma potential in the inner divertor increases twofold. At a higher line-averaged density, the NBI heating affects the edge plasma, namely, the electron temperature in the midplane scrape-off layer and the heating moves toward the divertor. Thus, a twice as high electron temperature is observed in the divertor and a bi-Maxwellian electron energy distribution function arises.

本文介绍了在中性射束注入 (NBI) 加热过程中通过朗缪尔探针在氘、L 模式等离子体中 COMPASS 开放偏滤器中局部等离子体参数的实验表征。针对不同线平均电子密度，在不同等离子体配置和不同磁场和等离子体电流方向下研究了核心等离子体的 NBI 加热对局部偏滤器等离子体参数的影响。线平均密度低于 6 10 ¹⁹ m ^-3，低 NBI 加热功率水平不会导致偏滤器区域中等离子体参数的任何显着变化。还发现，对于反向磁场，偏滤器中 NBI 的影响在更高的线平均电子密度和等离子体电流下更强。在偏滤器中，NBI 加热的影响在高输出功率（高于P _NBI = 320 kW）和线平均密度（高于 7 10 ¹⁹ m ^-3）。外靶处的电子温度和浮动电位分别增加了 10-50% 和 100%，而内偏滤器中的等离子体电位增加了两倍。在较高的线平均密度下，NBI 加热会影响边缘等离子体，即中平面刮除层中的电子温度，并且加热向偏滤器移动。因此，在偏滤器中观察到两倍高的电子温度，并且出现双麦克斯韦电子能量分布函数。