Instabilities of ideal magnetohydrodynamics mode and neoclassical tearing mode stabilization by electron cyclotron current drive for EHL-2 spherical torus

The next generation fusion device listed on ENN’s fusion roadmap, named as (ENN He-Long) EHL-2, is under both physics and engineering designs. The instabilities of ideal magnetohydrodynamics (MHD) mode and neoclassical tearing mode (NTM) stabilized by electron cyclotron current drive (ECCD) for EHL-2’s two typical operation scenarios are analyzed. For high-ion-temperature operating (HITO) scenario, the vertical displacement event (VDE) could be a big challenge to the device safety. For the steady-state operating (SSO) scenario, the limitation may rise from the ideal MHD mode, NTM, etc. This suggests that the MHD analysis of both operation scenarios should be done with different focusing. Preliminary analysis based on the current physics and engineering design of both two scenarios is given in this paper. Based on the analysis result of above, the future assessments might target at active control method and the effect of boron on MHD activities.