Reconnection heating experiments and simulations for torus plasma merging startup
Reconnection heating experiments and simulations for torus plasma merging startup
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环面等离子体合并启动的重连接加热实验和模拟
DOI：
10.1088/1741-4326/ab14a4
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发表时间：
2019
期刊：
影响因子：
3.3
通讯作者：
Horiuchi Ritoku
中科院分区：
文献类型：
--
作者：
Ono Yasushi;Inoue Shizuo;Tanabe Hiroshi;Cheng Chio-Zong;Hara Hirohisa;Horiuchi Ritoku
通过TS-3（TS-3U）、TS-4、MAST和ST-40等一系列的并合实验，揭示了高β球形托卡马克（ST）、球形托卡马克和场反向位形（FRC）并合过程中的重联加热特性。我们开发了MW级（TS-3U中< 30 MW）离子加热使用磁重联环面等离子体合并。合并实验和粒子在细胞（PIC）模拟（也部分太阳观测）同意，（一）离子加热的重联在其下游，（二）负电位形成在下游加速离子和（iii）低依赖性的离子加热的引导（环形）字段B g。一个重要的发现是，在磁轴q 0处的安全因子> 2的托卡马克工作区，重联加热能与重联磁场B rec有关，而与B g无关。等离子体团/电流片喷射促进了高Q区域中的离子加热，削弱了离子加热的B g依赖性。由于重连将离子加速到B rec的阿尔芬速度的70%，因此在恒定等离子体密度下，离子温度Ti增量（和重连加热能量）与B rec的平方成比例。这种有希望的重连加热不依赖于等离子体的大小，只要重连时间短于等离子体约束时间。扩展到1.2 keV以上的标度律表明，通过增加B rec，合并启动可以实现燃烧等离子体温度Ti> 10 keV。合并/重连加热可以探索一条新的直接燃烧等离子体的途径，而不需要使用任何额外的加热，如中性束注入（NBI）。这种缩放导致我们进行新的重连加热实验，以直接进入燃烧等离子体状态：托卡马克能源公司的ST-40和东京大学的TS-3U。
A series of merging experiments, TS-3 (TS-3U), TS-4, MAST and ST-40, made clear the promising characteristics of reconnection heating during merging formation of a high-beta spherical tokamak (ST), spheromak and field-reversed configuration (FRC). We developed the MW-class (< 30 MW in TS-3U) ion heating using magnetic reconnection of torus plasma merging. Both the merging experiments and particle-in-cell (PIC) simulations (and also partly solar observation) agree on,(i) ion heating of the reconnection in its downstream,(ii) negative potential formation in the downstream for accelerating ions and (iii) low dependence of ion heating on the guide (toroidal) field B g. An important finding is that the reconnection heating energy depends on the reconnecting magnetic field B rec but has little dependence on B g in the tokamak operation region with the safety factor at the magnetic axis q 0> 2. The plasmoid/current sheet ejection promotes ion heating in the high-q region, weakening the B g dependence of ion heating. Since the reconnection accelerated ions up to 70% of the Alfven speed of B rec, the ion temperature T i increment (and the reconnection heating energy) scales with B rec squared under the constant plasma density. This promising reconnection heating does not depend on plasma size, as long as the reconnection time is shorter than the plasma confinement time. This scaling law extended over 1.2 keV suggests that the merging start-up may realize the burning plasma temperature T i> 10 keV by increasing B rec. The merging/reconnection heating can explore a new direct route to burning plasma regimes without using any additional heating, such as neutral beam injection (NBI). This scaling leads us to new reconnection heating experiments for direct access to burning plasma regimes: ST-40 at Tokamak Energy and TS-3U at the University of Tokyo.