7月17日 Plasma-material interaction and plasma diagnostics in He containing plasmas

报告题目：Plasma-material interaction and plasma diagnostics in He containing plasmas

报告时间：2026年7月17日（星期五）10:00

报告地点：EAST大厅二楼会议室

报 告 人：Shin Kajita

报告人简介：

Shin Kajita教授于1977年出生于日本名古屋，2005年获东京大学博士学位，现任东京大学新领域创成科学研究科教授。其主要研究方向包括聚变装置偏滤器区域的等离子体-材料相互作用、氦等离子体辐照下金属表面纳米结构形成机制，以及相关纳米结构在光电化学领域的应用。长期以来，他围绕氦等离子体诊断、钨材料表面改性、纳米气泡与绒毛结构形成、瞬态热负荷损伤及单极电弧等问题开展了系统研究。

报告摘要：

Helium is produced in deuterium–tritium fusion reactors and plays an important role in both plasma diagnostics and plasma–material interactions. This presentation covers two main topics: (1) plasma diagnostics using helium emission and (2) helium-induced modification of tungsten plasma-facing materials.

For plasma diagnostics, a neural network was developed to infer electron density and electron temperature from helium optical emission spectroscopy (OES) in various linear plasma devices. Compared with conventional multiple regression methods, the model reduced prediction errors by more than half and achieved an accuracy of approximately 10% for new discharges when sufficient training data were available.

For plasma–material interactions, helium irradiation can induce the formation of nanobubbles and fuzz-like nanostructures on tungsten surfaces, leading to reduced thermal conductivity and enhanced field emission. These surface modifications can promote transient damage and unipolar arcing, resulting in tungsten erosion and impurity generation. The effects of helium irradiation under deposition conditions and its influence on arc formation will also be discussed.