Feasibility of applying the lower cut-off frequency for the density radial coverage extension in EAST reflectometry measurement

Jia HUANG; Xiang HAN; Kaixuan YE; Tao ZHANG; Fei WEN; Mingfu WU; Kangning GENG; Gongshun LI; Fubin ZHONG; Yukai LIU; Haoming XIANG; Shuqi YANG; Shoubiao ZHANG; Xiang GAO; Ge ZHUANG; the EAST Team

doi:10.1088/2058-6272/ac52e9

Plasma Science and Technology > 2022 > 24(5): 055104. > DOI: 10.1088/2058-6272/ac52e9

Jia HUANG, Xiang HAN, Kaixuan YE, Tao ZHANG, Fei WEN, Mingfu WU, Kangning GENG, Gongshun LI, Fubin ZHONG, Yukai LIU, Haoming XIANG, Shuqi YANG, Shoubiao ZHANG, Xiang GAO, Ge ZHUANG, the EAST Team. Feasibility of applying the lower cut-off frequency for the density radial coverage extension in EAST reflectometry measurement[J]. Plasma Science and Technology, 2022, 24(5): 055104. DOI: 10.1088/2058-6272/ac52e9

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Feasibility of applying the lower cut-off frequency for the density radial coverage extension in EAST reflectometry measurement

1.
University of Science and Technology of China, Hefei 230026, People's Republic of China
2.
Institute of Plasma Physics, Chinese Academy of Sciences, Hefei 230031, People's Republic of China
3.
Advanced Energy Research Center, Shenzhen University, Shenzhen 518060, People's Republic of China
4.
Key Laboratory of Optoelectronic Devices and Systems of Ministry of Education and Guangdong Province, College of Optoelectronic Engineering, Shenzhen University, Shenzhen 518060, People's Republic of China

More Information

Corresponding author:
Xiang HAN, E-mail: xiang.han@ipp.ac.cn

Ge ZHUANG, E-mail: gezhuang@ustc.edu.cn
Received Date: October 17, 2021
Revised Date: December 19, 2021
Accepted Date: February 07, 2022
Available Online: December 11, 2023
Published Date: May 22, 2022

Graphical Abstract

Abstract

Abstract

The extraordinary mode (X-mode) lower cut-off frequency is proposed for use in the reflectometry diagnostic on ITER for the electron density profile measurement, which is a trade-off between extreme plasma parameters and the accessible probing frequency. In contemporary experiments, the lower cut-off frequency can be identified at the probing frequency below the electron cyclotron frequency (f_ce) under certain plasma conditions. We provide here, for the first time, the experimental validation of the use of the lower cut-off frequency for the density profiles via the reflectometry measurement on EAST. The corresponding group delay of the lower cut-off frequency evolves continuously with the upper one, revealing a reasonable radial coverage extension of reflectometry measurement toward the plasma core. It is concluded that the lower cut-off frequency can be used as a supplement to the upper one in the density profile inversion process, which is of particular interest in the high magnetic field and/or density discharge to extend the radial coverage of reflectometry measurement.
- X-mode reflectometry,
- density profile,
- EAST,
- lower cut-off frequency

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Acknowledgments

The authors wish to acknowledge Dr. S. X. Wang for helping to analyze the POINT data. This work has been supported by the National Key R & D Program of China (Nos. 2017YFE0301205 and 2019YFE03040002), National Natural Science Foundation of China (Nos. 11875289, 11975271, 11805136, 12075284, and 12175277) and China Postdoctoral Science Foundation (No. 2021M703256).

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