Lower hybrid current drive experiments and improved performance on the HT-7 superconducting tokamak

Guang-li, Kuang; Liu, Yuexiou; Shan, Jiafang; Xu, Wenzhen; Zhang, Xiangqin; Liu, Deng-Cheng; Liu, Fukun; Zhu, Yubao; Zhang, Cheng; Zheng, Guodi; Wu, Jinyong; Lin, Jiande; Ding, Bingjun; Xu, Handong; Fang, Yue; Li, Jiangang; Luo, Junhua; Zhang, Xiaodong; Wan, Baonian; Qingchu, Zhao; Mao, Jiangyu; Gao, Xiang; Zhang, Shouyin; Li, Cheng-Fu; Gu, Xiaoxia; Qing, Pinjian; Fan, Heng‐Yu; Liu, Shengxia; Ling, Bili; Ding, Baoqing; Li, Yahong; Wu, Zhengwei; Jie, Yinxian; Liu, Sheng; Xie, Jinbo; Wan, Yuanxi

doi:10.1088/0029-5515/39/11y/317

Cited by 47 publications

(18 citation statements)

References 8 publications

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“…This could be improved by means of increasing the electron temperature, hence enhancing the single-pass absorption efficiency. Anyway, preliminary results showing that the current profiles are related to ϕ ∆ indicate the possibility of profile control by changing the wave spectrum, which has also been shown in previous LH experiments in many tokamaks [62][63][64][65][66][67]. Further experiments will be continued with hotter target plasma, e.g.…”

Section: Effect Of Power Spectrum On Current Drivesupporting

confidence: 61%

First results of LHCD experiments with 4.6 GHz system toward steady-state plasma in EAST

Liu

Ding

et al. 2015

Nucl. Fusion

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A 4.6 GHz lower-hybrid current drive (LHCD) system has been firstly commissioned in EAST in the 2014 campaign. The first LHCD results with 4.6 GHz show that LHW can be coupled to plasma with a low reflection coefficient, drive plasma current and plasma rotation, modify the plasma current profile, and heat plasma effectively. By means of configuration optimization and local gas puffing near the LHW antenna, good LHW-plasma coupling with a reflection coefficient less than 5% is obtained. The maximum LHW power coupled to plasma is up to 3.5 MW. The current drive (CD) efficiency is up to 1.1 × 10 19 A m −2 W −1 and the central electron temperature is above 4 keV, suggesting that LH power could be mainly deposited in the core region, which is in agreement with code simulation. Experiments show that the current profile is effectively modified and toroidal rotation in the co-current direction is driven by the LHCD. Also, the CD efficiency and current profile depend on the launched wave spectrum, suggesting the possibility of controlling the current profile by changing the phase difference. Repeatable H-mode plasma is obtained by either the 4.6 GHz LHCD system alone, or together with a 2.45 GHz LHCD system, the NBI (neutral beam injection) system. The different ELM features of H-mode between the different heating methods are under investigation.

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Section: Effect Of Power Spectrum On Current Drivesupporting

confidence: 61%

First results of LHCD experiments with 4.6 GHz system toward steady-state plasma in EAST

Liu

Ding

et al. 2015

Nucl. Fusion

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“…The major research fields on the HT-7 are steady-state operation, high-performance such as advanced tokamak operation modes, the fuelling study [27] and MARFE phenomena [28], lower hybrid wave (LHW) current drive [29] and ICRF heating [30]. For recent experiments on the HT-7, the following main diagnostics signals are effectively used in this paper as shown in Fig.…”

Section: Methodsmentioning

confidence: 99%

Study of confinement improvement in presence of a MARFE in the HT-7 superconducting tokamak

Asif¹

2006

Braz. J. Phys.

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A new set of actively cooled toroidal double-ring graphite limiters have been developed on the HT-7 tokamk for long pulse operation. In this paper, a Multifaceted asymmetric radiation from the edge (MARFE) phenomena and improved particle confinement induced by a MARFE, characterized by H α line emissions drops and the lineaveraged density increase have been studied in the HT-7 ohmic discharges (where the plasma current I p =145 kA, loop voltage V loop =2-3 V, toroidal field B T =1.7 T, and Z e f f =2-8). It is found that the improved particle confinement phase exists for about 90 ms and the particle confinement time τ P increased about 1.6 times.

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“…The plasma current, position and central line-averaged electron density are feedback controlled during discharges. A stainless-steel liner has been installed in the vacuum chamber at the radius of 0.32m [12,13]. A lower hybrid wave (LHW) power up to 0.6MW at 2.45GHz is available in the HT-7 tokamak.…”

Section: Experimental Set-upmentioning

confidence: 99%

Observation of Runaway Electron Behaviour During Disruptions in LHCD Discharges in the HT‐7 Tokamak

et al. 2010

Contrib. Plasma Phys.

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Production of runaway electrons during disruptions has been observed in the HT-7 Tokamak. The runaway current plateaus, which can carry part of the pre-disruptive current, are observed in lower-hybrid current drive (LHCD) limiter discharges. It is found that the runaway current can mitigate the disruptions effectively. We can use gas puffing to increase the line-averaged density to restrain the runaway electrons and rebuild the plasmas after the disruptions. Detailed observations are presented on the runaway electrons generated following disruptions in the HT-7 tokamak discharges. The results indicate that the magnetic oscillations play a significant role in the loss of runaway electrons in disruptions. There are two important preconditions to rebuild plasmas by runaway electrons after the disruptions. One of them are weak magnetic oscillations; another one are LHWs (lower-hybrid waves).

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Lower hybrid current drive experiments and improved performance on the HT-7 superconducting tokamak

Cited by 47 publications

References 8 publications

First results of LHCD experiments with 4.6 GHz system toward steady-state plasma in EAST

First results of LHCD experiments with 4.6 GHz system toward steady-state plasma in EAST

Study of confinement improvement in presence of a MARFE in the HT-7 superconducting tokamak

Observation of Runaway Electron Behaviour During Disruptions in LHCD Discharges in the HT‐7 Tokamak

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