Effect of lithium coating on long pulse high performance plasma discharges in EAST
Effect of lithium coating on long pulse high performance plasma discharges in EAST
复制标题
锂涂层对 EAST 长脉冲高性能等离子体放电的影响
DOI：
10.1088/1361-6587/ab9b3a
复制
发表时间：
2020-08-01
影响因子：
2.2
通讯作者：
Gao, X.
中科院分区：
文献类型：
--
作者：
Xu, W.;Hu, J. S.;Gao, X.
研究了采用锂蒸发涂层和实时锂粉喷射技术对高性能H模放电的杂质、燃料循环和氢含量的控制。结果表明，锂蒸发涂层显著降低了等离子体中低Z杂质碳和高Z杂质钨和钼的浓度，并且随着锂蒸发涂层的积累，杂质浓度显著降低，并保持了较好的稳定性。具体地说，在101 S H模放电过程中，高Z钨芯杂质浓度保持在3ppm-15ppm之间，这对于长脉冲工作是可以接受的。此外，在与35 S长脉冲H型放电类似的过程中，通过LPI进行的实时壁面处理成功地将堆芯高Z金属杂质减少了50%，显示出实时LPI与长脉冲放电之间的强大兼容性。此外，蒸发锂涂层还表现出了燃料循环控制，锂涂层燃料循环明显减少，并在之后保持良好。同时，随着锂涂层的积累，以密度比H/(H+D)表示的氢的少数组分含量从接近50%降至接近5%；低的氢含量提高了ICRF少数组分的加热效率。最终，实时LPI将回收系数R(全局)从0.95降低到0.82。在这些壁面条件的帮助下，101 S长脉冲H模放电过程中的等离子体密度得到了很好的控制。这些结果为EAST和未来聚变装置未来长脉冲高性能H模运行(S=400)的杂质、燃料回收和氢含量控制提供有价值的参考。
Control of impurities, fuel recycling and hydrogen content by lithium evaporative coatings and real-time lithium powder injection (LPI) in EAST are studied for high performance H-mode discharges of up to similar to 100 s. The results show that the lithium evaporative coatings significantly reduced both the low-Z impurity carbon and high-Z impurity tungsten as well as molybdenum concentration in the plasmas, and the impurities concentration significantly reduced with the accumulated lithium coatings and maintained well afterwards. Specifically the high-Z tungsten core impurity concentration was maintained between 3 ppm-15 ppm during the 101 s H-mode discharge, which is acceptable for the long pulse operation. In addition, real-time wall conditioning via LPI successfully reduced the core high-Z metal impurities by 50% during similar to 35 s long pulse H-mode discharge, exhibiting strong compatibility between real-time LPI with long pulse discharges. In addition, evaporative lithium coatings demonstrated fuel recycling control, with fuel recycling obviously reducing with lithium coatings and maintaining well afterwards. Also, the lithium evaporative coatings reduced the hydrogen minority species content, represented by the density ratio H/(H + D), from similar to 50% down to similar to 5% with accumulated lithium coatings; low hydrogen fraction improved the ICRF minority heating efficiency. Finally the real-time LPI reduced the recycling coefficientR(global)from 0.95 to 0.82. With these wall conditionings help, the plasma density controlled well during the 101 s long pulse H-mode discharge. These results provide valuable references on impurities, fuel recycling and hydrogen content control for future longer pulse high performance H-mode operation (>= 400 s) in EAST and future fusion devices.