Effect of Magnetic Configuration and Impurities with Neutral Beam Heating on EAST: Numerical Investigation

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

Abstract

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

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.

Figures/Tables 12

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

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

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

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

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

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

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

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

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

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

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

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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