Plasma cleaning of ITER edge Thomson scattering mock-up mirror in the EAST tokamak
Plasma cleaning of ITER edge Thomson scattering mock-up mirror in the EAST tokamak
复制标题
DOI：
10.1088/1741-4326/aa96b8
复制
发表时间：
2018-02
期刊：
影响因子：
3.3
通讯作者：
R. Yan;L. Moser;Baoguo Wang;Jiao Peng;C. Vorpahl;F. Leipold;R. Reichle;R. Ding;Junling Chen;L. Mu;R. Steiner;E. Meyer;Ming-Hua Zhao;Jinhua Wu;L. Marot
中科院分区：
文献类型：
--
作者：
R. Yan;L. Moser;Baoguo Wang;Jiao Peng;C. Vorpahl;F. Leipold;R. Reichle;R. Ding;Junling Chen;L. Mu;R. Steiner;E. Meyer;Ming-Hua Zhao;Jinhua Wu;L. Marot
第一面镜子是热核实验堆所有光学和激光诊断的关键要素。直接面对等离子体，第一反射镜的表面可能会被含能粒子溅射，或者沉积有从第一壁侵蚀的污染物(钨和铍)，这将导致反射率下降。杂质沉积强调了ITER第一次镜面原位清洗的必要性。用于ITER边缘汤姆森散射诊断的模拟第一镜系统首次在EAST使用射频电容耦合等离子体在托卡马克中进行了清洗。用直径为25 mm的钼镜镶件(直径25 mm)在样板上方5个位置(中心到边缘)沉积了10 nm的氧化铝作为铍的替代物，考察了其清洗性能，即污染物的去除和清洗的均匀性。用能量色散X射线能谱、反射率测量和X射线光电子能谱对清洗效果进行了评价。在实验室中使用无磁场的Ar或Ne等离子体，在EAST托卡马克装置上施加1.7T的磁场，可以均匀地去除氧化铝薄膜。EAST清洗后镜面反射率完全恢复，清洗效率约为无磁场清洗的40倍。所有这些结果都为ITER的等离子体清洗基线场景提供了良好的前景。
First mirrors are the key element of all optical and laser diagnostics in ITER. Facing the plasma directly, the surface of the first mirrors could be sputtered by energetic particles or deposited with contaminants eroded from the first wall (tungsten and beryllium), which would result in the degradation of the reflectivity. The impurity deposits emphasize the necessity of the first mirror in situ cleaning for ITER. The mock-up first mirror system for ITER edge Thomson scattering diagnostics has been cleaned in EAST for the first time in a tokamak using radio frequency capacitively coupled plasma. The cleaning properties, namely the removal of contaminants and homogeneity of cleaning were investigated with molybdenum mirror insets (25 mm diameter) located at five positions over the mock-up plate (center to edge) on which 10 nm of aluminum oxide, used as beryllium proxy, were deposited. The cleaning efficiency was evaluated using energy dispersive x-ray spectroscopy, reflectivity measurements and x-ray photoelectron spectroscopy. Using argon or neon plasma without magnetic field in the laboratory and with a 1.7 T magnetic field in the EAST tokamak, the aluminum oxide films were homogeneously removed. The full recovery of the mirrors’ reflectivity was attained after cleaning in EAST with the magnetic field, and the cleaning efficiency was about 40 times higher than that without the magnetic field. All these results are promising for the plasma cleaning baseline scenario of ITER.