Runaway electrons behaviors during ion cycolotron range of frequency and lower hybrid wave plasmas in the HT-7 Tokamak

Abstract

HT-7 Tokamak is equipped with a lower hybrid wave (LHW) system and an ion cyclotron range of frequency (ICRF) system. ICRF can accelerate ions effectively, while LHW can accelerate electrons effectively. The generation of runaway electrons during the LHW and ICRF plasmas, as well as the time evolution of electron temperature during the ICRF and LHW plasmas was investigated in this paper. The runaway critical energy for runaway electrons was also calculated according to the experimental data. It was observed that the combination of ICRF and LHW can produce a higher heating efficiency and a better coupling between ICRF and plasmas if the power of LHW exceeds a critical value. Therefore, the generation of runaway electrons and fusion neutrons are affected by ICRF.