Comparison of methods for turbulence Doppler frequency shift calculation in Doppler reflectometer

Xiaoming ZHONG; Xiaolan ZOU; Chu ZHOU; Adi LIU; Ge ZHUANG; Xi FENG; Jin ZHANG; Jiaxu JI; Hongrui FAN; Shen LIU; Shifan WANG; Liutian GAO; Wenxiang SHI; Tao LAN; Hong LI; Jinlin XIE; Wenzhe MAO; Zixi LIU; Wandong LIU

doi:10.1088/2058-6272/acc8ba

Plasma Science and Technology > 2023 > 25(9): 095104. > DOI: 10.1088/2058-6272/acc8ba

Xiaoming ZHONG, Xiaolan ZOU, Chu ZHOU, Adi LIU, Ge ZHUANG, Xi FENG, Jin ZHANG, Jiaxu JI, Hongrui FAN, Shen LIU, Shifan WANG, Liutian GAO, Wenxiang SHI, Tao LAN, Hong LI, Jinlin XIE, Wenzhe MAO, Zixi LIU, Wandong LIU. Comparison of methods for turbulence Doppler frequency shift calculation in Doppler reflectometer[J]. Plasma Science and Technology, 2023, 25(9): 095104. DOI: 10.1088/2058-6272/acc8ba

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Comparison of methods for turbulence Doppler frequency shift calculation in Doppler reflectometer

1.
School of Nuclear Science and Technology, University of Science and Technology of China, Hefei 230026, Peopleʼs Republic of China
2.
French Alternative Energies and Atomic Energy Commission, Institute for Magnetic Fusion Research, Saint-Paul-Lez-Durance F-13108, France
3.
Shenzhen University, Shenzhen 518061, Peopleʼs Republic of China

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Corresponding author:
Chu ZHOU, E-mail: zhouchu@ustc.edu.cn
Received Date: November 24, 2022
Revised Date: March 07, 2023
Accepted Date: March 28, 2023
Available Online: December 05, 2023
Published Date: June 05, 2023

Graphical Abstract

Abstract

Abstract

The Doppler reflectometer (DR), a powerful diagnostic for the plasma perpendicular velocity (u_⊥) and turbulence measurement, has been widely used in various fusion devices. Many efforts have been put into extracting the Doppler shift from the DR signal. There are several commonly used methods for Doppler shift extraction, such as the phase derivative, the center of gravity, and symmetric fitting (SFIT). However, the strong zero-order reflection component around 0 kHz may interfere with the calculation of the Doppler shift. To avoid the influence of the zero-frequency peak, the asymmetric fitting (AFIT) method was designed to calculate the Doppler shift. Nevertheless, the AFIT method may lead to an unacceptable error when the Doppler shift is relatively small compared to the half width at half maximum (HWHM). Therefore, an improved method, which can remove the zero-frequency peak and fit the remaining Doppler peak with a Gaussian function, is devised to extract the Doppler shift. This method can still work reliably whether the HWHM is larger than the Doppler shift or not.
- perpendicular velocity measurement,
- Doppler reflectometer,
- Doppler shift

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Acknowledgments

This work was supported in part by the National MCF Energy R&D Program (Nos. 2018YFE0311200 and 2017YFE0301204), National Natural Science Foundation of China (Nos. U1967206, 11975231 and 11922513). This work was also supported by the Users with Excellence Program of Hefei Science Center CAS (No. 2020HSC-UE009). We also acknowledge the EAST team for the aid.

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