Realization of electron cyclotron resonance heating and dual-step toroidal field coil current assisted startup in NCST

In the NanChang Spherical Tokamak (NCST), for the first time, experimental research was carried out on the dual-step toroidal field coil power supply system, which is specifically designed to assist the plasma current startup through electron cyclotron resonance heating (ECRH). The experimental results demonstrate that, in comparison to the preceding toroidal field coil power supply system, the dual-step toroidal field coil power supply system is more effective in aligning with the ECRH system and optimizing the utilisation of the toroidal electric field. This has resulted in an increase in plasma current from 30 kA to 40 kA, an extension of the discharge time from 47 ms to 123 ms, and a notable enhancement in the stability of the plasma.