Time resolved deposition measurements in NSTX

JOURNAL OF NUCLEAR MATERIALS

卷:337

Article; Proceedings Paper

Skinner, CH ; Kugel, H ; Roquemore, AL ; Hogan, J ; Wampler, WR

关键词: carbon deposition;    quartz microbalance;    hydrocarbon radicals;    NSTX;    Monte Carlo simulation;   

DOI  :  10.1016/j.jnucmat.2004.10.076

来源: Elsevier

【 摘 要 】

Time-resolved measurements of deposition in current tokamaks are crucial to gain a predictive understanding of deposition with a view to mitigating tritium retention and deposition on diagnostic mirrors expected in next-step devices. Two quartz crystal microbalances have been installed on NSTX at a location 0.77m outside the last closed flux surface. This configuration mimics a typical diagnostic window or mirror. The deposits were analyzed ex-situ and found to be dominantly carbon, oxygen and deuterium. A rear facing quartz crystal recorded deposition of lower sticking probability molecules at 10% of the rate of the front facing one. Time resolved measurements over a 4-week period with 497 discharges, recorded 29.2 mu g/cm(2) of deposition, however surprisingly, 15.9 mu g/cm(2) of material loss occurred at 7 discharges. The net deposited mass of 13.3 mu g/cm(2) matched the mass of 13.5 mu g/cm(2) measured independently by ion beam analysis. Monte Carlo modeling suggests that transient processes are likely to dominate the deposition. (c) 2004 Elsevier B.V. All rights reserved.

【 授权许可】

Free