Diagnostic development for parallel wave-number measurement of lower hybrid waves in EAST

Dataset · Tue Jun 21 00:00:00 EDT 2022

DOI:https://doi.org/10.7910/DVN/AF60VB· OSTI ID:1889413

Wang, Y. F. ^[1]; Ding, B. J.; Li, M. H.; Baek, S. G.; Wallace, G. M.; Liu, L.; Zhao, L. M.; Wang, M.; Wu, Z. G.; Liu, F. K.; Shan, J. F.; Zhang, X. J.; Li, Y. C.; Wu, C. B.

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1. OSTI

An eight-channel magnetic probe diagnostic system has been designed and installed adjacent to the 4.6 GHz lower hybrid (LH) grill antenna in the low-field side of the EAST tokamak in order to study the n|| evolution of lower hybrid waves in the first pass from the launcher to the core plasma. The magnetic probes are separated by 6.6 mm, which allows measurement of the dominant parallel refractive index n|| up to n|| =5 for 4.6GHz LH waves. The magnetic probes are designed to be sensitive to the magnetic field component perpendicular to the background magnetic field with a slit on the casing that encloses the probe. The intermediate frequency (IF) stage, which consists of two mixing stages, down-coverts the frequency of the measured wave signals at 4.6 GHz to 20 MHz. A bench test demonstrates the phase stability of the magnetic probe diagnostic system. By evaluating the phase variation of the measured signals along the background magnetic field, the dominant n|| of the LH wave in the scrape-off layer (SOL) has been deduced during the 2019 experimental campaign. In the low density plasma, the measured dominant n|| of the lower hybrid waves is about 2.1, corresponding to the main peak 2.04 of the launched n|| spectrum. The n|| deduced by the least square linear fit method remains near this value in the low density plasma with a high spatial correlation magnitude of 0.9. With an eight-channel probe system a wave-number spectrum has also been deduced, which has a peak near to the measured dominant n||.

• Research Organization: Massachusetts Inst. of Technology (MIT), Cambridge, MA (United States). Plasma Science and Fusion Center
• Sponsoring Organization: USDOE Office of Science (SC), Fusion Energy Sciences (FES)
• DOE Contract Number: SC0010492
• OSTI ID: 1889413
• Country of Publication: United States
• Language: English

Related Subjects

70 PLASMA PHYSICS AND FUSION TECHNOLOGY