Hydrogen recycling and tritiurn retention at plasma facing wall in a fusion reactor

最近发展的成像板（IP）技术给出了JT-60 U D-D放电中面向等离子体碳瓦上氚沉积的详细图，并使直接比较氚分布和碳沉积图案成为可能。这促使我们比较H，D和T在不同托卡马克中的保留行为，并调查差异的来源。在JET中，大部分T与碳（D/C = 0.75）共同沉积在偏滤器阴影区，特别是在低温泵前面的百叶窗上，而JT-60 U偏滤器瓦片上沉积层中的氢和氘保留（H+D/C比）要小得多。这两台机器都是在较高的壁温（约550 K）下运行的。在JT-60 U中，偏滤器瓦片是惯性冷却的，瓦片表面温度很容易达到600 K，有时超过1000 K。然而，在JET中，偏滤器安装结构是水冷的，使得尽管偏滤器瓦片的表面温度 ...更多信息 在等离子体放电过程中，在撞击点附近也可以超过1000 K，它们的本体温度被限制在低得多的温度（355- 420 K）。这使我们得出结论，偏滤器的温度以及因此的共沉积层的温度可以对氚保留起重要作用，并且可以通过调整面向等离子体的部件的表面温度来显著减少氚保留。在TFTR中，即使在缓冲器限制器的侵蚀主导区域中，我们也发现在所有瓦片的侧面上有大量的氚共沉积，其不直接面对等离子体。这表明，大量被侵蚀的碳不会长距离移动，而是迅速重新沉积，当然，在侵蚀占主导地位的地区，它会立即重新被侵蚀。考虑到现有的碳沉积和H、D、T在面向等离子体的碳材料中的滞留数据，对碳基D-T反应器中的氚滞留量进行了估算，特别是从滞留氚存量减少的角度进行了估算。少

The recently developed imaging plate (IP) technique gives a detailed map of tritium deposition on plasma facing carbon tiles used in JT-60U D-D discharges and makes it possible for the direct comparison of tritium distribution and carbon deposition pattern. This motivates us to compare the retention behavior of H, D and T in different tokamaks and to investigate from where the differences originate. In JET, most of the T is co-deposited with carbon (D/C〜0.75) in the divertor shadowed region, particularly on louvers in front of the cryogenic pumps, while hydrogen and deuterium retention (in H+D/C ratio) in the deposited layers on JT-60U divertor tiles is much smaller. Both machines are operated at elevated wall temperatures (around 550K). In JT-60U, the divertor tiles are inertially cooled and tile surface temperatures easily reach 600K, sometimes more than 1000K. However, in JET the divertor mounting structure is water cooled, so that although the surface temperature of divertor tiles … More can also exceed 1000K near the strike points during plasma discharges, their bulk temperatures are restrained to a much lower temperature (〜355-420K). This lead us to conclude that the temperature of the divertor and therefore of the co-deposited layer could play an important role on the tritium retention and it may be possible to reduce tritium retention significantly by tailoring the surface temperature of plasma facing components.In TFTR, even in erosion dominated regions of the bumper limiter, we have found large amount of tritium codeposition on the sides of all tiles, which do not directly face the plasma. This indicates that large amount of eroded carbon does not travel long distances but is rather promptly re-deposited, where of course it is immediately re-eroded in erosion dominated areas. Taking the available data on carbon deposition and retention of H, D and T in the plasma facing carbon materials into account, tritium retention in a carbon based D-T reactor, particularly from the aspect of retained tritium inventory reduction is estimated. Less