LAUSR

Abstract H-mode discharges with edge localized modes (ELMs) have been achieved in the HL-2A tokamak with combined auxiliary heating of NBI and ECRH. In order to realize the mitigation or suppression of ELMs in HL-2A plasmas and also to explore the ELM suppression and other 3D magnetic field physics, a set of compact in-vessel resonant magnetic perturbation (RMP) coils (2×2 array) has been recently designed and installed on the HL-2A tokamak to meet the limited space requirement. There are two rows of coils (upper and lower separated poloidally 66.5°), with each row consisting of 2 coils separated from each other by 180° along the toroidal direction. Each coil spans about 11.4° toroidally. Meanwhile, an integral solid-state regulating power supply system with a high switching frequency and an AC–DC–AC converter configuration has been designed and fabricated for the RMP system. It can provide DC and AC with various waveforms. The maximum amplitude of DC is 5.0 kA and the frequency of AC can reach 3 kHz. These in-vessel coils can produce sufficient RMPs in the plasma edge during typical HL-2A H-mode discharges. The ELM mitigation by applying an n = 1 RMP has been observed in recent HL-2A experiments. The ELM frequency was increased by a factor of 2 and the amplitude of the Dαemission decreased, leading to a reduced heat load on the divertor plates.