Progress towards high regimes on HL-2A

Significant progress has been made recently in the following areas: the first High coupling efficiency of lower-hybrid current drive (LHCD) with the Passive-Active Multi-junction (PAM) antenna was successfully demonstrated in H-mode on the HL-2A tokamak; double critical impurity gradients of electromagnetic turbulence were observed in H-mode plasmas; A new pedestal mode, leading an inward particle flux, was observed prior to each ELM onset; Various ELM mitigation techniques have been investigated, including supersonic molecular beam injection (SMBI), impurity seeding, resonant magnetic perturbation (RMP) and lower-hybrid wave (LHW); The ion internal transport barrier was observed in the neutral beam injection (NBI) heated plasmas; Neoclassical tearing modes (NTMs) driven by the transient perturbation of local electron temperature during the non-local thermal transport events have been observed, and a new-type non-local transport triggered by the ion fishbone was found; Long-lasting runaway electron plateau was achieved after argon injection and the runaway current was successfully suppressed by SMBI; It was found that low-n Alfvenic ion temperature gradient (AITG) modes can be destabilized in ohmic plasmas even with weak magnetic shear and low pressure gradients; For the first time, the synchronization of geodesic acoustic mode (GAM) and magnetic fluctuations was observed in the edge plasmas, revealing the frequency entrainment and phase lock; Spatiotemporal features of zonal flows have been studied by using multi-channel correlation Doppler reflectometers. (author)