Millimeter-wave imaging of magnetic fusion plasmas: technology innovations advancing physics understanding

Abstract

Electron cyclotron emission imaging (ECEI) passively collects spontaneous emission at harmonics of the cyclotron frequency, ω ce , and produces a 2D image of electron temperature, T e , for a poloidal cross-section of optically thick plasma [1][2][3][4][5][6]. It utilizes the fact that the cyclotron frequency in a tokamak depends on the major radius, leading to a 1:1 mapping between emission intensity and the local T e value. Along the poloidal direction, T e is imaged onto a vertically aligned array of antennas. Figure 1 illustrates both conventional 1DNuclear Fusion

Development and application of radar reflectometer using micro to infrared waves

“…It is seen that a clear correlation is observed in the poloidal direction in the H-mode plasma. MIR systems have been applied to various magnetically confined plasmas in the world such as DIII-D, LHD, KSTAR, ASDEX-U, and EAST, and produces useful information regarding fluctuations [48][49][50][51].…”

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

“…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 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]. It is comprised of a quasi-optical system, a front-end 24 channel heterodyne imaging array with a tunable RF from 60 GHz to 135 GHz, and a set of back-end ECEI electronics that together generate 24(poloidal)×16(radial)=384 channel images of the 2D temperature fluctuations.…”

“…With the characteristic of local measurement, good accessibility, and without external perturbation to plasmas, more and more attentions have been paid to microwave diagnostics by scientists, and some new techniques have been developed and applied to the hardware development, signal processing and data interpretation in recent twenty years. So far, significant progresses have been made, especially on ECEI, microwave imaging reflectometry (MIR), multi-channel DBS reflectometer and high temporal resolution frequency modulation (FM) reflectometers [12][13][14][15][16][17][18][19].…”

Modeling the electron cyclotron emission below the fundamental resonance in ITER

“…2R 4.7 w + 98.2,(11) as well as the value of f ′ for which T rad remains below 1% of T e,0 ,f ′ (T rad < 0.01T e,0 ) = −0.88T e,0 − 4.6R 4.7 w + 96.1, (12) valid for f ′ ∈ [55; 75] in GHz, T e,0 ∈ [15; 40] in keV, and R w ∈ [0.6; 0.9]. Either of these two limits on T rad should be easily detectable by any sensitive radiometer.…”