Progress of long pulse and H-mode experiments in EAST

Abstract

Significant progress, on both the technological and physical fronts, towards high-performance, long-pulse plasma discharges has been made in EAST (the experimental advanced superconducting tokamak) since the last IAEA FEC. With enhanced operational capabilities, the following key results have been achieved with lithium wall conditioning: fully steady-state long-pulse diverted plasmas entirely driven by the lower hybrid current drive (LHCD) over 400 s and stationary H-mode discharges over 30 s with LHCD and ion cyclotron resonant heating (ICRF). H-modes with various types of edge localized modes (ELMs) have been achieved with HIPB98(y,2) ranging from 0.7 to over unity, providing great opportunities for the study of H-mode physics. New and exciting physics with dominant radio-frequency heating has emerged, including new findings of LHCD-induced 3D edge magnetic topology and its effect on ELM dynamics and particle and heat deposition; the role of zonal flows during the L–H transition and I-phase; and a new turbulence-flow cycle state at the H-mode pedestal. Various means for mitigating ELMs have also been demonstrated to facilitate long-pulse operation, including supersonic molecular beam injection, as well as innovative solid Li granule injection. A brief overview of these recent advances is presented.