ヘリウム損傷ナノ構造形成タングステンの冷却特性と損傷回避法

Abstract

Precise evaluation of radiation cooling capability of the tungsten with fiber-form nanostructure is done using an electron beam power calibration system. It is found that the total emissivity of black nanostructured tungsten is very close to 1.0, meaning a complete black body. Discrepancies for the determination of total emissivity between the electron beam method and the fixed biasing procedure were discussed in terms of energy transmission through the plasma sheath, focusing on the ion energy reflection and the cooling associated by secondary electron emission. Some recovery techniques to obtain an almost original flat tungsten surface from nanostructured one is introduced, emphasizing on ITER-grade tungsten. Finally the effect of thin carbon layer on the formation of nanostructure on the tungsten surface is demonstrated as a mitigation technique.