EAST上磁位形和杂质对束离子约束和加热影响的数值模拟

doi:10.19596/j.cnki.1001-246x.8548

摘要/Abstract

摘要：

利用程序ORBIT和TRANSP/NUBEAM模拟研究全超导托卡马克实验装置(EAST)等离子体位形和杂质的特征参数Z_eff(有效电荷数)对束离子约束和加热的影响。结果表明: 在等离子体位形中, 随着最后一个封闭通量表面与中面外容器壁之间的距离(gapout)和环向磁场强度的增加, 快离子的损失(包含瞬时损失和波纹损失)也随之减少, 因此中性束的加热效率随着gapout的增加而提高。此外, 随着背景等离子体杂质的增加(即Z_eff的增加), 增加了束损失, 导致最后束加热效率降低。选择合适的磁位形, 同时降低背景的杂质含量可以增强快离子约束, 提高束的加热效率。

关键词: 中性束注入, 磁位形, 有效电荷数, 快离子约束, 快离子损失

Abstract:

Effects of plasma configuration and effective ion charge (Z_eff) with neutral beam heating on EAST are studied with guiding center codes ORBIT and TRANSP/NUBEAM. The resultes show that the fast-ion loss (including prompt and ripple losses) decreases as the distance between the last closed flux surface and the outer vessel wall in the mid-plane(gapout) and the toroidal magnetic field increases in the magnetic configuration. As a result the beam-ion confinement are enhanced and the heating efficiency is increased. Moreover, as the background plasma impurities increase, i.e., Z_eff increases the beam-ion loss increases, resulting in the reduction of beam-ion heating efficiency. Thus, choosing appropriate magnetic configuration and reducing the background impurity content enhance the fast-ion confinement and improve the beam heating efficiency.

Key words: neutral beam injection, magnetic configuration, effective ion charge, fast-ion confinement, fast-ion loss

刘源煜, 向东, 龚学余, 路兴强. EAST上磁位形和杂质对束离子约束和加热影响的数值模拟[J]. 计算物理, 2023, 40(3): 282-290.

Yuanyu LIU, Dong XIANG, Xueyu GONG, Xingqiang LU. Effect of Magnetic Configuration and Impurities with Neutral Beam Heating on EAST: Numerical Investigation[J]. Chinese Journal of Computational Physics, 2023, 40(3): 282-290.

图/表 12

表1 在EAST上具有不同注入方向和切向半径Rtan的中性束参数

Table 1 Neutral beams with different injection directions and tangential radius Rtan on EAST

束线端口	注入方向	切向半径R_tan/m
NBI-AL	同向	1.26
NBI-AR	同向	0.73
NBI-DL	同向	1.14
NBI-DR	同向	0.61
NBI-FL	反向	0.61
NBI-FR	反向	1.14

图1 EAST 98839炮(红线)和98840炮(蓝线)的参数随时间的变化(a) 等离子体电流；(b) gapout

Fig.1 The parameters of EAST shots 98839 (the red line) and 98840 (the blue line) as functions of time (a) plasma current; (b) gapout

图2 模拟参数剖面(a) 电子温度(Te，黑色线)和离子温度(Ti，蓝色线)；(b) 电子密度(Ne)

Fig.2 Parameter profiles in the simulation (a) electron temperature (Te, black line) and ion temperature (Ti, blue line); (b) electron density (Ne)

图3 EAST 98839炮(红线)，98840炮(绿线)的加热特性(a)中性束注入背景离子的总加热功率(图例中有最终加热份额。)；(b)束离子沉积剖面

Fig.3 Heating characteristics of shot 98839 (the red line) and shot 98840 (the green line) on EAST (a) all bull-ion heating power for NBI (final beam-ion heating fraction in the legend); (b) beam-ion deposition distribution

表2 不同gapout下束离子的各项损失份额

Table 2 Loss fractions of beam ions in different gapout

炮号	gapout/cm	第一轨道损失/%	波纹损失/%	穿透损失/%
98839	6.0	2.3	4.1	6.3
98840	4.5	3.3	4.7	7.6

表3 不同磁场强度时等离子体参数和束参数

Table 3 Parameters of plasma and beam ion in different magnetic field

炮号	环向磁场B_T/T	离子体电流I_p/MA	束注入功率P_int/MW	束注入能量E_nb/kev
101700	1.755	0.4	0.98	56
101701	1.979	0.4	0.98	56
101705	2.204	0.4	0.98	56
101707	2.427	0.4	0.98	56

图4 不同磁场强度时背景等离子体的(a) 电子温度(Te)和离子温度(Ti)，(b) 电子密度(Ne)剖面

Fig.4 Parameter profiles of background plasma in different magnetic field (a) electron temperature (Te) and ion temperature (Ti), (b) electron density (Ne)

图5 EAST实验炮101700炮(蓝线)，101701炮(黑线)，101705炮(红线)和101707炮(绿线)的(a)总加热效率中性束注入背景离子加热功率(图例中有最终加热份额)以及(b)束离子功率沉积剖面

Fig.5 Heating characteristics of shot 101700 (the blue line), shot 101701 (the black line), shot 101705 (the red line) and shot 101707 (the green line) on EAST (a) all bull-ion heating power for NBI (final beam-ion heating fraction in the legend), (b) beam-ion deposition distribution

表4 在不同环向磁场下束离子的各项损失份额

Table 4 Loss fractions of beam ions in different toroidal magnetic field

炮号	第一轨道损失/%	波纹损失/%	穿透损失/%
101700	3.8	5.2	6.2
101701	3.5	5.0	6.2
101705	3.3	4.2	6.1
101707	3	3.9	6.1

图6 总加热效率中性束注入背景离子加热功率(图例中有最终加热份额。) (a) 101700炮，(b) 101705炮

Fig.6 All bull-ion heating power for NBI (final beam-ion heating fraction in the legend) (a) shot 101700, (b) shot 101705

表5 不同Zeff下束离子的各项损失份额

Table 5 Loss fractions of beam ions at different Zeff

炮号	第一轨道损失/%	波纹损失/%	穿透损失/%
101700 (Z_eff=1.9)	3.8	5.0	7.2
101700 (Z_eff=3.0)	4.1	5.3	7.1
101705 (Z_eff=1.9)	3.3	4.2	7.1
101705 (Z_eff=3.0)	3.7	4.5	7.1

图7 不同Zeff下NBI快离子初始分布(黑色虚线是捕获-通行边界。) (a) 101700炮；(b) 101705炮

Fig.7 Initial distributions of NBI fast ions at different Zeff (Black dashed lines are capture-passage boundaries.) (a) shot 101700; (b) shot 101705

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