Development of Microwave Imaging Diagnostics on the HL-2A Tokamak

Abstract

Microwave imaging reflectometry (MIR) and electron cyclotron emission imaging (ECEI) systems have been developed on the HL-2A tokamak to visualize the density and temperature fluctuations. The MIR system is comprised of a quasi-optical system, a four frequency microwave source and receiver system that generate 8(poloidal) × 4(radial) × 2(toroidal) = 64 channel images of density fluctuations. The ECEI system is comprised of a quasi-optical system, a front-end 24 channel heterodyne imaging array with a tunable RF from 75 to 110 GHz, and a set of back-end ECEI electronics that together generate 24(poloidal) × 8(radial) = 192 channel images of the 2D temperature fluctuations. Characteristics of both systems are presented. Simulations and laboratory tests of both optical systems have been conducted. The test results are in good agreement with simulations.

Progress of microwave diagnostics development on the HL-2A tokamak

“…Three microwave interferometer systems are developed to measure the plasma line-averaged density and density fluctuations in the main plasma and divertor regions [22,23]. The multi-channel ECE and ECEI are developed to measure the electron temperature profiles and fluctuations [24][25][26][27][28][29][30]. Three frequency modulation continuous wave (FMCW) reflectometers and two amplitude modulation (AM) reflectometers are developed to measure the density profiles from low field side in the horizontal plane [31][32][33][34].…”

“…Microwave imaging diagnostic systems have made important contributions to plasma physics study and have been adopted at major fusion facilities worldwide [7,19]. The ECEI and MIR systems have been developed to visualize the two/threedimensional (2D/3D) density and temperature fluctuations on the HL-2A tokamak [12,[27][28][29][30]. The ECEI system is developed in collaboration with UC Davis [19,27,28].…”