Control of sawtooth via ECRH on EAST tokamak

Yuan, Yifei; Hu, Liqun; Xu, Liqing; Wang, Xiaoguang; Wang, Xiaojie; Xu, Handong; Luo, Z.P.; Chen, Kaiyun; Lin, Shiyao; Duan, Yanmin; Chang, Pengxiang; Zhao, Hailin; He, Kang; Liang, Y.

doi:10.1063/1.4953605

Cited by 13 publications

(9 citation statements)

References 13 publications

(15 reference statements)

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“…However, the counter-ECCD seems to have few effects on the mode stabilization. The sawtooth period is found to be minimized in EAST experiments [14] when the ECRH resonance location is deposited to be just inside the q =1 surface, as shown in the Fig. 11(b).…”

Section: Preliminary Results From Ecrhmentioning

confidence: 96%

Recent progress of RF-dominated experiments on EAST

et al. 2017

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Abstract. The research of EAST program is mostly focused on the development of high performance steady state scenario with ITER-like poloidal configuration and RF-dominated heating schemes. With the enhanced ITER-relevant auxiliary heating and current drive systems, the plasma profile control by coupling/integration of various combinations has been investigated, including lower hybrid current drive (LHCD), electron cyclotron resonance heating (ECRH) and ion cyclotron resonance heating (ICRH). The 12 MW ICRH system has been installed on EAST. Heating and confinement studies using the Hydrogen Minority Heating scheme have been investigated. One of the importance challenges for EAST is coupling higher power into the core plasma, experiments including changing plasma position, electron density, local gas puffing and antenna phasing scanning were performed to improve ICRF coupling efficiency on EAST. Results show that local gas injection and reducing the k|| can improve the coupling efficiency directly. By means of the 4.6 GHz and 2.45 GHz LHCD systems, H-mode can be obtained and sustained at relatively high density, even up to ne ~ 4.5 × 10 19 m -3, where a current drive effect is still observed. Meanwhile, effect of source frequency (2.45GHz and 4.6GHz) on LHCD characteristic has been studied on EAST, showing that higher frequency improves penetration of the coupled LH (lower hybrid) power into the plasma core and leads to a better effect on plasma characteristics. Studies demonstrate the role of parasitic effects of edge plasma in LHCD and the mitigation by increasing source frequency. Experiments of effect of LH spectrum and plasma density on plasma characteristics are performed, suggesting the possibility of plasma control for high performance. The development of a 4MW ECRH system is in progress for the purpose of plasma heating and MHD control. The built ECRH system with 1MW source power has been successfully put into use on EAST in 2015. H-mode discharges with L-H transition triggered by ECRH injection were obtained and its effects on the electron temperature, particle confinement and the core MHD stabilities were observed. By further exploring and optimizing the RF combination for the sole RF heating and current drive regime, fully non-inductive H-mode discharges with V loop~0 V has progressed steadily in the 2016 campaign. The overview of the significant progress of RF dominated experiments is presented in this paper.

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Section: Preliminary Results From Ecrhmentioning

confidence: 96%

Recent progress of RF-dominated experiments on EAST

et al. 2017

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“…Till now, the launcher is stably operated under 100 s pulse length with 500kW injection power. The influence on sawtooth period and tearing mode stabilizing were investigated due to the flexible steering capability [21].…”

Section: Engineering Commissioningmentioning

confidence: 99%

Research activities and progress on the long pulse ECRH launcher for EAST

et al. 2019

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A long pulse Electron Cyclotron Resonance Heating (ECRH) system is developed on EAST tokamak for plasma heating and current profile tailoring. The ECRH system is designed to operate at 140GHz and to inject 4MW CW power. With respect to the physical objectives of the newly built ECRH system, a quasi-optical launcher is designed to inject 4MW continuous wave into plasma through an equatorial port. Gaussian beams delivered from evacuated corrugation waveguides will be focused and reflected by high thermal conductive metal mirrors, and then steered by using push-rod steering mechanism with entire scanning range of ±25° toroidally and over 30° poloidally in plasma cross section. The mirrors are carefully designed with mega watts power handling capability and optimum optical characteristics. The performance of steering mechanism has been tested before installation, an open-loop control system for ECRH launcher has been implemented for required mirror movement and proper polarization between plasma discharges. This paper will present the overall design and progress of the launcher, along with the performance in EAST campaigns. Considerations and possible upgrade of the design features relevant to long pulse operation are discussed.

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“…[15][16][17] Furthermore, in EAST, it is observed that the combined heating of LHW and ECRH can alleviate and avoid the effect of the sawtooth oscillation on the impurity transport. [18][19][20] The results regarding this combined heating for improving the core impurity confinement will be beneficial to the EAST long-pulse steady-state and high-performance operation with tungsten divertor.…”

Section: Introductionmentioning

confidence: 99%

Reduction of impurity confinement time by combined heating of LHW and ECRH in EAST*

Xu¹,

Wu²,

Zhang³

et al. 2021

Chinese Phys. B

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The core impurity confinement properties are experimentally investigated in the Experimental Advanced Superconducting Tokamak (EAST) plasma heated by lower hybrid wave (LHW) and electron cyclotron resonance heating (ECRH) (LHW+ECRH). It is shown that the impurity confinement time (τ imp) in the L-mode plasma jointly heated by LHW and ECRH is weakly dependent on electron density but strongly dependent on the heating power, thus it is shorter than that in LHW-only heated L-mode plasma with the similar plasma parameters. The combined heating of LHW and ECRH can reduce the collisionality and indicates a more effective heating method for core τ imp reduction and normalized poloidal beta (β P) improvement. It should be emphasized that in this high β P operation window the small ELM regime can be accessed, and an L-mode level τ imp (40 ms–80 ms) and high β N (∼ 1.7) can be obtained simultaneously. It means that this typical small ELMy H-mode regime has an advantage in avoiding the serious tungsten accumulation, and will be competitive in future long-pulse steady-state and high-performance operation with high-Z material plasma-facing components.

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Control of sawtooth via ECRH on EAST tokamak

Cited by 13 publications

References 13 publications

Recent progress of RF-dominated experiments on EAST

Recent progress of RF-dominated experiments on EAST

Research activities and progress on the long pulse ECRH launcher for EAST

Reduction of impurity confinement time by combined heating of LHW and ECRH in EAST*

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