Author:
Luo Chen-Xi,Zeng Long,Zhu Xiang,Tang Tian,Qiu Zhi-Yong,Lin Shi-Yao,Zhang Tao,Liu Hai Qing,Shi Tong-Hui,Zhang Bin,Ding Rui,Gao Wei,Wang Min-Rui,Gao Wei,Ti Ang,Zhao Hai Lin,Zhou Tian-Fu,Qian Jin-Ping,Sun You-Wen,Lv Bo,Zang Qing,Jie Yin-Xian,Liang Yun-Feng,Gao Xiang
Abstract
Abstract
The generation of runaway electrons (REs) is observed during the low-density helium ohmic plasma discharge in the Experimental Advanced Superconducting Tokamak (EAST). The growth rate of hard x-ray (HXR) is inversely proportional to the line-average density. Besides, the RE generation in helium plasma is higher than deuterium plasma at the same density, which is obtained by comparing the growth rate of HXR with the same discharge conditions. The potential reason is the higher electron temperature of helium plasma in the same current and electron density plateau. Furthermore, two Alfvén eigenmodes driven by REs have been observed. The frequency evolution of the mode is not fully satisfied with the Alfvén scaling and when extension of the Alfvén frequency is towards 0, the high frequency branch is ~50 kHz. The different spatial position of the two modes and the evolution of the helium concentration could be used to understand deviation between theoretical and experimental observation.
Subject
General Physics and Astronomy