中国物理B ›› 2006, Vol. 15 ›› Issue (12): 2989-2999.doi: 10.1088/1009-1963/15/12/037

• PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES • 上一篇    下一篇

Experimental characteristics of a lower hybrid wave multi-junction coupler in the HT-7 tokamak

丁伯江, 单家方, 刘甫坤, 方瑜德, 韦 维, 吴振伟, 陈忠勇, 徐汉东, 王 茂, 蒋 敏, 张公让, 黄 峰, 赵燕平, 匡光力, HT-7 team   

  1. Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031,China
  • 收稿日期:2006-03-17 修回日期:2006-08-07 出版日期:2006-12-20 发布日期:2006-12-20
  • 基金资助:
    Project supported by the National Natural Science Foundation of China (Grant Nos 10205015 and 10575104).

Experimental characteristics of a lower hybrid wave multi-junction coupler in the HT-7 tokamak

Ding Bo-Jiang(丁伯江)† , Shan Jia-Fang(单家方), Liu Fu-Kun(刘甫坤), Fang Yu-De(方瑜德), Wei Wei(韦维), Wu Zhen-Wei(吴振伟), Chen Zhong-Yong(陈忠勇), Xu Han-Dong(徐汉东), Wang Mao(王茂), Jiang Min(蒋敏), Zhang Gong-Rang(张公让), Huang Feng(黄峰), Zhao Yan-Ping(赵燕平), Kuang Guang-Li(匡光力), and HT-7 team   

  1. Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031,China
  • Received:2006-03-17 Revised:2006-08-07 Online:2006-12-20 Published:2006-12-20
  • Supported by:
    Project supported by the National Natural Science Foundation of China (Grant Nos 10205015 and 10575104).

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摘要： A phase-controlled lower hybrid wave (LHW) multi-junction (MJ) coupler (3(rows)×(columns)× (subwaveguides)) has been developed in the HT-7 tokamak. Simulations show that it is more effective for driving plasma current than an ordinary phase-controlled LHW antenna (3(rows)×12(columns)) (traditional coupler). The plasma--wave coupling experiments show that the reflection coefficient (RC) is below 10%, implying that the MJ grill can launch the wave into the plasma effectively. The effect of power spectrum launched by the MJ coupler on RC indicates that an optimal condition is requisite for a better coupling in the lower hybrid current drive (LHCD) experiments. Studies indicate that the drive efficiency of the MJ antenna is higher than that of the traditional one, which is mainly ascribed to the discrepancy in impurity concentration, plasma temperature, and spectrum directivity. An improved confinement with an electron internal transport barrier is obtained by LHCD. The analysis shows that the modified negative (low) magnetic shear and the change of radial electric field profile due to LHCD are possible factors responsible for the eITB formation.

Abstract: A phase-controlled lower hybrid wave (LHW) multi-junction (MJ) coupler (3(rows)×(columns)× (subwaveguides)) has been developed in the HT-7 tokamak. Simulations show that it is more effective for driving plasma current than an ordinary phase-controlled LHW antenna (3(rows)×12(columns)) (traditional coupler). The plasma--wave coupling experiments show that the reflection coefficient (RC) is below 10%, implying that the MJ grill can launch the wave into the plasma effectively. The effect of power spectrum launched by the MJ coupler on RC indicates that an optimal condition is requisite for a better coupling in the lower hybrid current drive (LHCD) experiments. Studies indicate that the drive efficiency of the MJ antenna is higher than that of the traditional one, which is mainly ascribed to the discrepancy in impurity concentration, plasma temperature, and spectrum directivity. An improved confinement with an electron internal transport barrier is obtained by LHCD. The analysis shows that the modified negative (low) magnetic shear and the change of radial electric field profile due to LHCD are possible factors responsible for the eITB formation.

Key words: antenna, plasma heating, plasma confinement

中图分类号:  (Electromagnetic waves (e.g., electron-cyclotron, Whistler, Bernstein, upper hybrid, lower hybrid))

  • 52.35.Hr
52.25.Fi (Transport properties) 52.25.Vy (Impurities in plasmas) 52.40.Fd (Plasma interactions with antennas; plasma-filled waveguides) 52.55.Fa (Tokamaks, spherical tokamaks) 52.55.Wq (Current drive; helicity injection)