Abstract—

Hydrogen glow discharge cleaning (H-GDC) is a routine conditioning procedure for the modern tokamaks and the future fusion machines, including ITER. Due to the low energy of hydrogen ions in glow discharge plasmas, the probability of any considerable damage to the plasma-facing components was mainly ignored. In this work, Tungsten, as the primary candidate for the plasma-facing materials in tokamaks, is considered for studies regarding effects of the H-GDC procedure on the material during a routine vacuum vessel conditioning in Damavand tokamak. After performing routine H-GDC using pure hydrogen, the formation of loosely attached nanostructured bundles (NSBs) on the surface of the tungsten samples was observed. The presence of the NSBs, which can be a source of dust, would be significant due to their possible effects on the functionality of the future fusion plasma devices. The NSBs are observed on the tungsten samples with the surface temperature of <370 K after 2.5–4 hours of hydrogen ion bombardment with incident energy of ≈120 eV and fluence of ≈(2–3.5) × 10²² m^–2. The surface modifications of specimens exposed to H‑GDC were examined using a material probe experiment and several surface analysis techniques such as SEM, EDX, XRD, and ERDA. Therefore, the formation of loose nanostructures on the wall of plasma confinement vessels due to H-GDC draws attention to probable damaging effects of this phenomenon upon functionality and outcomes of tokamaks.

中文翻译：

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氢辉光放电清洗钨的副作用的研究

摘要-

氢辉光放电清洗（H-GDC）是现代托卡马克及未来的聚变设备（包括ITER）的常规调节程序。由于辉光放电等离子体中氢离子的能量低，主要忽略了面对等离子体的组件受到任何重大损坏的可能性。在这项工作中，钨被用作托卡马克中面向等离子体的材料的主要候选材料，被认为是在达马万德托卡马克的常规真空容器调理过程中研究H-GDC程序对材料的影响的研究。在使用纯氢执行常规H-GDC之后，观察到钨样品表面上形成的松散附着的纳米结构束（NSB）。NSB的存在可能是灰尘的来源，由于它们可能对未来的融合等离子体装置的功能产生影响，因此具有重要意义。在钨离子轰击2.5–4小时后，在钨样品上观察到的表面温度<370 K的NSB，入射能量≈120eV，能量密度约为≈（2-3.5）×10²² m ^–2。使用材料探针实验和几种表面分析技术（例如SEM，EDX，XRD和ERDA）检查了暴露于H-GDC的样品的表面改性。因此，由于H-GDC，在血浆限制血管壁上形成的松散的纳米结构引起人们对这种现象对托卡马克功能和结果的可能破坏作用的关注。