Abstract

The erosion and redeposition of first-wall armor materials is a problem in nuclear fusion devices with carbon walls, where deuterium, tritium, and (eroded) carbon present in the plasma are deposited on the walls of the device, trapping the expensive and radiologically hazardous tritium. Thermo-oxidation, in which vessel surfaces are heated and oxygen containing gas is injected, is a possible solution. It results in the production of carbon oxides and tritiated water vapor, which can be pumped out by the vacuum pumps and recycled in a tritium recycling facility. In the present study, thermogravimetric analysis was used to measure the mass loss (or gain) of codeposited specimens from the General Atomics DIII-D National Fusion Facility under thermo-oxidation, in addition to laser thermal desorption spectroscopy. X-ray photo-electron spectroscopy was also used in this work to examine the tile’s surface composition pre and post oxidation. Dust scraped from the specimen was also studied, as this is a surrogate for dust that naturally falls from the tile codeposits and builds up in the tile gaps. One key conclusion is that boron oxides form where boron is present in the codeposit as an impurity, and these oxides dominate the weight-change behavior of the codeposit specimens for long exposures.

摘要

在具有碳壁的核聚变装置中，第一壁装甲材料的腐蚀和再沉积是一个问题，其中等离子体中存在的氘，tri和（侵蚀的）碳沉积在装置的壁上，从而捕获了昂贵且具有放射性危害的装置氚。一种可能的解决方案是热氧化，其中加热容器表面并注入含氧气体。它会产生碳氧化物和ti化的水蒸气，可以通过真空泵将其抽出并在t回收设施中进行回收。在本研究中，除了激光热脱附光谱法外，热重分析还用于测量通用原子DIII-D国家聚变设施在热氧化条件下共沉积标本的质量损失（或增益）。在这项工作中还使用了X射线光电子能谱，以检查氧化前后瓷砖的表面成分。还研究了从标本刮下的灰尘，因为这是自然从瓷砖共存处掉落并堆积在瓷砖缝隙中的灰尘的替代物。一个重要的结论是，氧化硼形成于共存物中硼作为杂质存在的地方，并且这些氧化物支配了长时间暴露于共存样品的重量变化行为。