プラズマ対向面での損耗・再堆積研究の進展 2．正味損耗分布モデルと模擬実験

摘要

Estimation　of　net－erosion　profile　is　requisite　for　evaluating　the　lifetime　of　divertor　plates　under　high　heat and　particle　fluxes　of fusion　plasmas．As　a　reference　in　benchmark　tests　of numerical　calculation codes，a self－consistent　analytical　solution　is　presented for　a　simplified　divertor　condition，wherein　the　magnetic　field　line is normal　to　the　target plate　and the ionization mean free path of sputtered particles is assumed constant.The primary　flux　profile　of hydrogen　and　impurities　are　externally　given　as　well　as　the　return ratio　of　sputtered atoms　to　the　target.　In　the　direction　along　the　divertor　trace，all　conditions　are　uniform．The　analytical　solution is compared with net－erosion experiments carried out using the Compact Helical System（CHS）．The deposition profiles　of　Ti　and　O　impurities　are　in　very　good　agreement　with　the　analytical　predictlons，Recent　preliminary　results　observed　on　divertor　plates　in　the　Large　Helical　Device（LHD）are　briefly　presented．