Study of energetic particle physics with advanced ECEI system on the HL-2A tokamak

Abstract

Abstract. Understanding the physics of energetic particles (EP) is crucial for the burning plasmas in next generation fusion devices such as ITER. In this work, three types of internal kink modes (a saturated internal kink mode (SK), a resonant internal kink mode (RK), and a double e-fishbone) excited by energetic particles in the low density discharges during ECRH/ECCD heating have been studied by the newly developed 24(poloidal) × 16(radial) = 384 channel ECEI system on the HL-2A tokamak. The SK and RK rotate in the electron diamagnetic direction poloidally and are destabilized by the energetic trapped electrons. The SK is destabilized in the case of qmin > 1, while the RK is destabilized in the case of qmin < 1.The double e-fishbone, which has two m/n = 1/1 modes propagating in the opposite directions poloidally, has been observed during plasma current ramp-up with counter-ECCD. Strong thermal transfer and mode coupling between the two m/n = 1/1 modes have been studied.

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].…”

“…The optical system has been optimized to match the curvature of the field [13]. This system has been installed and successfully operated on the HL-2A tokamak, and 2D structures of the MHD activities, such as double e-fishbones, tearing mode, sawtooth crash and Alfven eigenmodes, have been clearly observed [9,28,29]. The MIR system comprises a quasi-optical system, a four-frequency microwave source and a 16-antenna (8 in poloidal and 2 in toroidal) receiver system that generate 8 (poloidal)×4 (radial)×2 (toroidal)=64 channel images of the density fluctuations.…”

Development of a 105 GHz fast ion collective Thomson scattering diagnostic on HL-2A tokamak

“…Fast ions originated from auxiliary neutral beam injection or ion cyclotron resonance heating have become a major concern in magnetic confinement fusion, since those energetic particles provide free energy for excitation of multitudinous Alfvenic modes [1,2], which may degrade the fast ion confinement and affect the bulk plasma dynamics [3][4][5][6]. Collective Thomson scattering (CTS) diagnostic, a powerful tool for mapping out the fast ion phase space distribution by providing spatially localized measurements of the ion velocity distribution, is firstly used to measure the fast ion evolution on JET [7].…”