Optimization of the chamfering structures for ITER-like W/Cu monoblocks to avoid the leading edge-induced melting in EAST
Optimization of the chamfering structures for ITER-like W/Cu monoblocks to avoid the leading edge-induced melting in EAST
复制标题
优化类似 ITER 的 W/Cu 整体块的倒角结构，以避免 EAST 中的前缘诱导熔化
DOI：
10.1016/j.fusengdes.2020.111951
复制
发表时间：
2020
影响因子：
1.7
通讯作者：
Xu Guoliang
中科院分区：
文献类型：
--
作者：
Li Changjun;Zhu Dahuan;Ding Rui;Wang Baoguo;Chen Junling;Gao Binfu;Xie Hai;Xu Guoliang
自2014年以来，EAST已经为真空室上部的目标安装了一个完整的类似iter的W分流器，带有W/Cu单体。虽然采用了环形和径向切割1 mm的双倒角成形结构（1 mm × 1 mm）来减轻前缘诱导的热效应，但在内外靶上都广泛观察到严重的前缘诱导熔化。所有熔化只发生在相邻卡带模块之间的前缘（inter- cm），而在一个卡带模块内相邻单块之间的前缘（intra-CM）没有发现熔化。为了优化倒角结构以避免熔化，采用有限元法对W/Cu单块进行了热分析。结果表明，目前的双倒角成形结构（1 mm × 1 mm）由于径向偏差较大，难以控制，甚至可能达到3 mm，因此不适用于内部cm。在如此大的偏差下，电流结构的最大表面稳态热负荷仅为1.2 MW m−2。因此，本文提出了一种对称结构，可以在两种不同的环向磁场下适应EAST操作要求，以提高热性能和避免熔化。在cm间，提出了适合较大误差和热通量的优化倒角结构。热评价后，目前的双倒角成形结构仍保持在cm内。这种对称CMs应确保EAST在热流高达3 MW m−2的情况下运行，偏差水平为3 mm。并对进一步改进以承受更高的热流密度提出了建议和讨论。
EAST has installed a full ITER-like W divertor with W/Cu monoblocks for targets in the upper part of vacuum chamber since 2014. Although the dual chamfer shaping structure with 1 mm cutting in both toroidal and radial directions (1 mm × 1 mm) has been employed to mitigate the leading edge-induced thermal effect, severe leading edge-induced melting was widely observed on both inner and outer targets. All melting only occurred at the leading edges between neighboring cassette modules (inter-CMs), while it was not found at the leading edges between neighboring monoblocks within one cassette module (intra-CM). To optimize the chamfering structure for avoiding melting, thermal analysis of W/Cu monoblocks was performed by finite element method. It is identified that the current dual chamfer shaping structure (1 mm × 1 mm) does not work for inter-CMs due to the large radial misalignment which was hardly controlled and could even reached up to 3 mm. With such large misalignment, the maximum surface steady state heat load is only 1.2 MW m−2for current structure. Thus, a symmetric structure of CMs which survive EAST operations requirement with two different toroidal magnetic fields has been proposed to improve the thermal performance and avoid melting. At inter-CMs, the optimized chamfering structure suitable for larger misalignments and heat fluxes has been suggested. And, the current dual chamfer shaping structure is remained at intra-CM after thermal evaluation. Such symmetric CMs should ensure EAST operate with heat flux up to 3 MW m−2with 3 mm misalignment level. And, further improvement to withstand a higher heat flux is also proposed and discussed.