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

最新发展的成像板（IP）技术给出了用于JT-60U D-D放电的等离子体面碳瓦上氚沉积的详细图，并使直接比较氚分布和碳沉积模式成为可能。这促使我们比较H， D和T在不同托卡马克中的保留行为，并研究差异的来源。在JET中，大部分T与碳共沉积（D/C ~ 0.75）在导流器阴影区，特别是在低温泵前的百叶窗上，而JT-60U导流器瓦上沉积层中的氢和氘保留（以H+D/C比）要小得多。这两种机器都在高壁温度（约550K）下运行。在JT-60U中，导流瓦是惯性冷却的，瓦表面温度很容易达到600K，有时甚至超过1000K。然而，在JET中，导流器安装结构是水冷的，因此，尽管在等离子体放电过程中，导流器瓦的表面温度也可以超过1000K，但它们的整体温度被限制在一个更低的温度（~ 355-420K）。这使我们得出结论，分流器和共沉积层的温度可能对氚潴留起重要作用，并且有可能通过调整面向等离子体组件的表面温度来显着减少氚潴留。在TFTR中，即使在缓冲器限制器的侵蚀主导区域，我们也发现大量的氚共沉积在所有瓦片的侧面，而不是直接面对等离子体。这表明，大量被侵蚀的碳不会长距离移动，而是相当迅速地重新沉积，当然，在侵蚀为主的地区，它会立即被重新侵蚀。结合现有的等离子体面碳材料中碳沉积和H、D、T的滞留数据，对碳基D-T反应器中的氚滞留量，特别是从滞留氚库存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