Effect of the transmission line on the ion temperature measured by the retarding field analyzer
Kangzhong Xu,
Hai Liu,
Yuhong Xu,
Zhipeng Chen,
Jun Cheng,
Haifeng Liu,
Xianqu Wang,
Jie Huang,
Xin Zhang,
Changjian Tang,
Junren Shao,
J-TEXT Team
Affiliations
Kangzhong Xu
Institute of Fusion Science, School of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031, People’s Republic of China
Hai Liu
Institute of Fusion Science, School of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031, People’s Republic of China
Yuhong Xu
Institute of Fusion Science, School of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031, People’s Republic of China
Zhipeng Chen
International Joint Research Laboratory of Magnetic Confinement Fusion and Plasma Physics, State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan 430074, People’s Republic of China
Jun Cheng
Institute of Fusion Science, School of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031, People’s Republic of China
Haifeng Liu
Institute of Fusion Science, School of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031, People’s Republic of China
Xianqu Wang
Institute of Fusion Science, School of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031, People’s Republic of China
Jie Huang
Institute of Fusion Science, School of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031, People’s Republic of China
Xin Zhang
Institute of Fusion Science, School of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031, People’s Republic of China
Changjian Tang
Institute of Fusion Science, School of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031, People’s Republic of China
Junren Shao
Institute of Fusion Science, School of Physical Science and Technology, Southwest Jiaotong University, Chengdu 610031, People’s Republic of China
J-TEXT Team
International Joint Research Laboratory of Magnetic Confinement Fusion and Plasma Physics, State Key Laboratory of Advanced Electromagnetic Engineering and Technology, School of Electrical and Electronic Engineering, Huazhong University of Science and Technology, Wuhan 430074, People’s Republic of China
Due to the presence of capacitance in the transmission line, the current collected by the retarding field analyzer (RFA) becomes asymmetrical (i.e., hysteresis) during voltage scanning, and it further affects the measurement of the ion temperature (Ti). In this article, we first analyze the hysteresis of the RFA’s I–V characteristics measured in the edge plasma of the J-TEXT tokamak, and we found that the ion temperature fitted from the falling side of the collector current is about 14% higher than that fitted from the rising side. An analytic model is built and verified by experimental results. Based on the model, the influence of the capacitance of transmission lines and the frequency of the scanning voltage on the hysteresis is investigated. It is found that the hysteresis becomes more remarkable with increasing capacitance or scanning frequency. Besides, the impact of the capacitance and the scanning frequency on the Ti measurement is also studied, which indicates that Ti is overestimated due to the hysteresis. The temperature error is linearly dependent on the capacitance and the scanning frequency. Furthermore, the analytical results are expected to be used in the prediction of scanning frequency for RFA applications.
