Electron cyclotron emission quasi-optical transmission system on the HL-3 tokamak

Journal Article · 22 November 2024 · Review of Scientific Instruments

DOI: https://doi.org/10.1063/5.0231756 · OSTI ID:2478408

Yu, X.  ^[1]; Shi, Z. B.  ^[2]; Yang, Z. C.  ^[2]; Jiang, M.  ^[2]; Chen, W. ^[2]; Yu, G. Y.  ^[3]; Zhu, Y. L.  ^[3]; Deng, W. C.  ^[2]; Zhou, Y.  ^[2]; Shen, Y. Q.  ^[2]; Wen, J.  ^[2]; Shi, P. W.  ^[2]; Han, K. X.  ^[2]

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1. Southwestern Institute of Physics, Chengdu (China); University of California, Davis, CA
2. Southwestern Institute of Physics, Chengdu (China)
3. University of California, Davis, CA (United States)

A new quasi-optical (QO) Electron Cyclotron Emission (ECE) transmission system has been established on the HL-3 tokamak, which includes a focusing QO mirror combination and a long-distance transmission line. This system was developed to meet the requirements for poloidal spatial resolution and the high signal-to-noise ratio needed for magnetohydrodynamic (MHD) instability studies using ECE on the HL-3. The QO mirror combination was installed inside the vacuum chamber for focusing. Laboratory test results, theoretical calculations, and synthetic ECE simulation results indicate that the Gaussian beam can meet the spatial resolution requirements for the accurate measurement of the MHD instability on the q = 1/2/3 surfaces, corresponding to the poloidal mode numbers m = 3/6/9. This includes good diagnostic poloidal spatial resolution for the important 2/1 and 3/2 modes. At the front end of the transmission line, a high-efficiency mode converter was designed to transition the TE₁₀ mode to the HE₁₁ mode for input into the transmission line, with an insertion loss of less than 1.5 dB. A 30 m long-distance corrugated oversized waveguide was constructed, with transmission losses ranging from 6 to 10 dB in the 60–120 GHz range. Polarization adjustment results show that the polarization offset and geometric spatial polarization angle change consistently, which can provide a reference for polarization adjustment in other complex structured transmission lines. As a result, the newly established ECE QO transmission system will provide strong support for future physics research involving ECE on the HL-3.

• Research Organization: University of California, Davis, CA (United States)
• Sponsoring Organization: Innovation Program of Southwestern Institute of Physics; National Magnetic Confinement Fusion Science Program of China; National Natural Science Foundation of China; USDOE Office of Science (SC)
• Grant/Contract Number: FG02-99ER54531; SC0023500
• OSTI ID: 2478408
• Journal Information: Review of Scientific Instruments, Journal Name: Review of Scientific Instruments Journal Issue: 11 Vol. 95; ISSN 0034-6748
• Publisher: American Institute of Physics (AIP)Copyright Statement
• Country of Publication: United States
• Language: English