Technical Design of Arc-Discharge and Deceleration Power Supply for MW Level NBI System on HL-2A Tokamak

Neutral beam injection (NBI) is one of the most effective ways to heat and drive plasma in a tokamak. The mega watt level neutral beam injector on the HL-2A tokamak consists of four high-power ion sources. Each source is supplied by discharge, beam extraction and auxiliary power supplies. Some circuit topologies and control sequences designed for the system are presented in this paper. Some important technologies such as the notching circuit, insulated gate bipolar transistor (IGBT) series-connected switch, high-frequency switching power supply and control system based on a digital signal processor (DSP) have been used. The system can be effectively used for high current ion beam extraction, protection, ion optics and so on. The power system has been safely used in HL-2A high-parameter NBI experiments for three years. The power of NBI can be kept at higher than 0.75MW for 1 second and the ion beam power extracted from the ion source is higher than 2MW. The ion temperature of the plasma center is close to 2.0keV. These results show that the design of this power system is reasonable and reliable, and it can fully meet the system requirements for NBI of the HL-2A tokamak.