Characterization of beam ion loss in high poloidal beta regime on EAST

作者：Jing Fu, J. Huang, Junwen Wang, Limin Yu, M. A. Van Zeeland, Jinming Chang, Baolong Hao, Jiale Chen, Muquan Wu, W H Hu, Zong Xu, Wei Gao, Wei Gao, Jie Su, Yuxin Sun, R.R. Liang, Qing Zang, Haiqing Liu, Bo Lyu, Guoqiang Zhong, Bin Zhang, Xiaojing Gong, EAST Team · 发表于：Plasma Physics and Controlled Fusion · 年份：2022 · DOI：10.1088/1361-6587/ac77b7 · 被引用次数：6 · 研究领域：Magnetic confinement fusion research、Particle accelerators and beam dynamics、Fusion materials and technologies

Abstract A critical issue for achieving the integrated operation of steady-state long-pulse high-confinement (H-mode) plasmas on experimental advanced superconducting tokamak (EAST) is to improve beam ion population confinement during neutral beam injection (NBI). To study the characterization of beam ion loss and improve beam ion confinement, the steady-state long pulse scenario discharges were conducted on EAST ( β p ⩾ 2.0, β N ⩾ 1.7, q 95 ⩾ 6.7 and H 98y2 ⩾ 1.1) with NBI heating. Based on neutron yield, the beam voltage and line-averaged electron density were adjusted from 50 kV to 60 kV and 4.4 × 1019 m −3 to 5.0 × 10 19 m −3 , respectively. The results show that the dominant mechanisms of beam ion loss are shine-through loss, prompt loss, and stochastic ripple loss. The shine-through loss fraction is determined by initial velocity, flight time and entire beam path. The change in prompt loss fraction is caused by the change in the deposition of beam ions. The change in stochastic ripple loss fraction is caused by the change in the initial fraction of trapped-confined ions. Detailed physics shows that the prompt loss fraction during counter-Ip injections (∼45%) is far larger than during co-Ip injections (∼5%) due to the finite orbit width. The lost ions are mainly deposited on the lower divertor or below the midplane since the direction of magnetic drift is vertical down. The orbit types of prompt loss during counter-Ip injections are mainly trapped-lost and ctr-passing lo...