The study of MARFE during long pulse discharges in the HT-7 tokamak

Abstract

Lower hybrid current drive (LHCD) experiments have been carried out to achieve high performance for long pulse operation in the HT-7 superconducting tokamak. Multifaceted asymmetric radiation from the edge (MARFE) phenomena is summarized and studied in the HT-7 tokamak. MARFE during LHCD discharge often occurs at the value of Zeff1/2fGW in range of 0.6–0.9. These MARFEs generally appear to have the same characteristics as high fGW density MARFEs and are locally stable throughout the LHCD pulse. The MARFE instability typically occurs at a fraction 33% of the nGW density during LHCD discharge, and it can often terminate the long pulse discharges in the HT-7 tokamak.