Title: Plasma response to rotating resonant magnetic perturbations with a locked mode in the J-TEXT tokamak

Abstract

Disruption affected by locked modes (LMs) is one of the most critical issues to be solved for tokamak fusion reactors. This paper aimed to understand the plasma response to external rotating resonant magnetic perturbations (RMPs), which are applied at a few kilohertz for controlling the pre-existing LMs. In the J-TEXT tokamak, the plasma response to a rotating RMP showed a feature of travelling wave, if no tearing mode (TM) existed. With a LM, the application of a rotating RMP led to unique features of plasma responses, which could be roughly described by the formula δb_θ(θ, t)=2Asin(mθ–mθ_O)cos(2πf_RRMPt), where δb_θ, A, m, θ_O and f_RRMP are the perturbed poloidal magnetic field, the amplitude, the poloidal mode number, the poloidal location of the TM's O-point and the frequency of the rotating RMP. These features are analogous to that of a standing wave in the TM rest frame, with the nodes locating at the O-/X- points. The perturbations of electron temperature, T_e, due to plasma responses were zero or minimal inside the magnetic island or outside the magnetic island but at the same poloidal positions as the O-/X- points. Both δb_θ and the T_e perturbations increased linearly with the rotating RMP. A phenomenological modelmore » is presented that the rotating RMP drives the phase oscillation of the TM by applying a periodical electromagnetic torque. Then the phase oscillation of TM, combined with the poloidal gradient of the plasma parameters, induces the plasma response measured experimentally. The nonlinear numerical modelling confirmed the forced phase oscillation of the TM, and qualitatively verified the amplitude and phase dependences among the plasma response, the phase oscillation of the TM and the rotating RMP, which have been predicted by the model.« less

Authors:

Wang, Nengchao  ^[1];

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Rao, Bo ^[1]; Hu, Qiming ^[2]; Ding, Yonghua ^[1]; Chen, Zhipeng ^[1]; Yang, Zhoujun ^[1]; Guo, Daojing ^[1]; Huang, Zhuo ^[1]; Ji, Xinke ^[1]; Li, Da ^[1]; Li, Jianchao ^[1]; Li, Mao ^[1]; Pan, Xiaoming ^[1]; Xu, Guo ^[1]; Yu, Q. ^[3]; Zhuang, G. ^[1]; Pan, Yuan ^[1]

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+ Show Author Affiliations

1. Huazhong Univ. of Science and Technology, Wuhan (China)
2. Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)
3. Max Planck Inst. fur Plasmaphysik, Garching (Germany)

Publication Date:

Fri Jan 04 00:00:00 EST 2019

Research Org.:

Princeton Plasma Physics Laboratory (PPPL), Princeton, NJ (United States)

Sponsoring Org.:

USDOE

Contributing Org.:

J-TEXT team

OSTI Identifier:

1513267

Grant/Contract Number:  

AC02-09CH11466

Resource Type:

Accepted Manuscript

Journal Name:

Nuclear Fusion

Additional Journal Information:

Journal Volume: 59; Journal Issue: 2; Journal ID: ISSN 0029-5515

Publisher:

IOP Science

Country of Publication:

United States

Language:

English

Subject:

70 PLASMA PHYSICS AND FUSION TECHNOLOGY