Investigation about The mechanism of wall saturation and refreshment in long time plasma-wall interaction

长时间稳态运行是未来聚变装置的关键问题。在长持续时间放电中，出现了具有长时间常数的现象，尽管这些现象在短脉冲放电中看不到。“壁饱和和刷新”现象就是其中之一。为了调查。基于壁面饱和和刷新机制，建立了等离子体Hu强度剖面测量系统，并介绍了蒙特-卡罗模拟程序。德加此外，还对超导托卡马克TRIAM-1 M装置长时间放电过程中的全局粒子平衡进行了分析。在TRIAM-1 M装置上进行的3 h放电中，H_u线强度在1030 min时自发增加，加料压电阀通过反馈控制自动关闭。A1 1 × 30 mm，壁的氢吸收和释放之间的总体平衡（即，壁饱和），然后仅通过再循环通量维持等离子体密度直到放电结束。H_u强度的环形分布的测量结果表明，H_u强度的增加（即流入等离子体）是由整个环形区的贡献引起的。从极向限制器和主室的温度迹线来看，壁饱和似乎是由于主室温度升高导致的氢释放增加而引起的。提出了壁面饱和和刷新现象与氢在壁面中的滞留量有关。墙，这取决于放电的历史。在DEGAS的模拟中，用中性氢粒子均匀释放的模型几乎可以再现H_u强度的极向分布。主腔室表面的整个区域。

Longtime steady-state operation is a critical issue for future fusion devices. In long duration discharges, phenomena with a long 'time-constant appear, although those cannot be seen in short pulse discharges. A phenomenon of "wall saturation and refreshment" is one of those. In order to investigate the. mechanism of the wall saturation and refreshment, we constructed a measurement system of profiles of Hu intensity 'of the plasma and we introduced a Monte-Carlo simulation code. "DEGAS". Moreover, an analysis of a global particle balance during long duration discharges has been carried out in the superconducting tokamak TRIAM-1M.In a 3-hour discharge on TRIAM-1M, the H_u line intensity spontaneously increased at 〜 30 min and the piezoelectric valve for the fueling was automatically closed by feedback control. A1 1〜30 mm, the global balance between the hydrogen absorption and release, of the wall (i.e., wall saturation) was achieved, and then the plasma density was maintained by the recycling flux alone until the end of the discharge. The measurement result of the toroidal profile of the H_u intensity indicates that the increase in the H_u, intensity (i.e. influx to the, plasma) is caused by the contribution from the whole toroidal area. From the temperature trace of the poloidal limiter and the main chamber, the wall saturation seems to be caused by the increase in hydrogen release from the main chamber due to its temperature increase. It is suggested that the phenomenon of the wall saturation and refreshment depends on the amount of retained hydrogen in the. wall, which depends on the history of the discharges. In the simulation of DEGAS, the. poloidal profile of H_u, intensity can be almost reproduced using a model in which neutral hydrogen particles ire released uniformly from the. whole area of the main chamber surface.