Experimental characteristics of a lower hybrid wave multi-junction coupler in the HT-7 tokamak
Experimental characteristics of a lower hybrid wave multi-junction coupler in the HT-7 tokamak作者机构：Institute of Plasma Physics Chinese Academy of Sciences Hefei 230031 China HT-7 team
出 版 物：《Chinese Physics B》 (中国物理B（英文版）)
年 卷 期：2006年第15卷第12期
页 面：2989-2999页
核心收录：
学科分类：07[理学] 070201[理学-理论物理] 0702[理学-物理学]
基 金：Project supported by the National Natural Science Foundation of China (Grant Nos 10205015 and 10575104).Acknowledgement 0ne of the authors Ding B J would like to thank the members of HT-7 Team for their cooperation and kindly help
主 题：antenna plasma heating plasma confinement
摘 要：A phase-controlled lower hybrid wave （LHW） multi-junction （M J） coupler （3（rows）×4（columns）×4 （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 plasm-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.
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