Plasma heating by electron cyclotron wave and the temperature effects on lower hybrid current drive on EAST

Nuclear Fushion

article

M.H. Li¹  H.D. Xu¹  X.J. Wang¹  M. Wang¹  B.J. Ding¹  C.B. Wu¹  G.H. Yan¹  L. Liu¹  L.M. Zhao¹  Z.G. Wu¹  W.Y. Xu¹  D.J. Wu¹  L.Y. Zhang¹  Y.Y. Tang¹  H. Li³  G.M. Wallace⁴  S.G. Baek⁴  P.T. Bonoli⁴  Q. Zang¹  S.Y. Lin¹  L.Y. Meng¹  H.L. Zhao¹  L.Q. Xu¹  M.R. Wang¹  X.J. Zhang¹  J. Huang¹  J.P. Qian¹  X.Z. Gong¹ 

[1] Institute of Plasma Physics, Chinese Academy of Sciences;University of Science and Technology of China;Advanced Energy Research Center, Shenzhen University;MIT Plasma Science and Fusion Center

关键词: electron cyclotron resonance heating (ECRH);    lower hybrid current drive (LHCD);    current drive efficiency;    collisional absorption;   

DOI  :  10.1088/1741-4326/acbec9

来源: Institute of Physics Publishing Ltd.

【 摘 要 】

This paper presents the progress in the long—pulse operation of the electron cyclotron (EC) system and the achievements in high—electron temperature plasmas by the combined EC and lower hybrid (LH) waves heating since the EC system was built in 2015. An electron temperature of up to 12 keV with a duration over 100 s was realized by the simultaneous heating of EC and LH waves at the line-averaged density {bar n_{ext{e}}}∼ 1.8×10¹⁹ m⁻³. The plasma heating effect strongly depends on the location of EC power deposition. H-mode plasmas with solely EC wave auxiliary heating have been obtained on EAST for the first time. These H-mode discharges show an enhanced confinement factorH _98(y,2) around 1.0, which is higher than the previous H-mode using LH power alone (Xuet al2011Nucl. Fusion51072001). The total heating power is very close to the threshold value for L–H transition according to the international tokamak scaling. In addition to the temperature effects inside the separatrix, higher electron temperature produced by EC wave is found to reduce the LH power loss in the scrape-off layer due to collisional absorption, which is beneficial to further increase the LH current drive efficiency. Ray-tracing/Fokker–Planck modeling results indicate that higher electron temperature can shorten the LH wave propagation on EAST in a multiple-pass regime, thus decreasing the collisional dissipation.

【 授权许可】

Unknown