Recent progress on the J-TEXT three-wave polarimeter-interferometer
Yuhan Wang, Li Gao, Peng Shi, Xin Xu, Yinan Zhou, Qinglong Yang, Chengyu Yang, Qinlin Tao, Chengshuo Shen, Yajun Wang, Lu Wang, Zhipeng Chen, Donghui Xia, Zhongyong Chen, Nengchao Wang, Zhoujun Yang, Yonghua Ding, Yuan Pan
Abstract
Abstract The J-TEXT three-wave polarimeter-interferometer system (POLARIS), which measures time-space distribution of electron density and current density, has been optimized with both the optical system and the equilibrium reconstruction method. The phase resolution of a Faraday rotation angle has been improved from 0.1 to 0.06 degree in chords from –0.18 to 0.18 m (plasma minor radius), and the sawtooth oscillation behavior has been detected by Faraday rotation angle measurement. By combining the POLARIS measured data and the equilibrium and fitting code (EFIT), an upgraded equilibrium reconstruction method has been developed, which provides a more accurate temporal and spatial distribution of current density and electron density. By means of the optimized POLARIS and improved equilibrium reconstruction, variations of profiles with increasing density have been carried out, under both Ohmic and electron cyclotron resonance heating discharges.