Comparison of ELM-Filament Mitigation Between Supersonic Molecular Beam Injection and Pellet Injection on HL-2A**supported by National Natural Science Foundation of China (Nos. 11075046, 10975049, 11375054, 11275060), the National Magnetic Confinement Fusion Science Program of China (Nos. 2013GB112008, 2013GB107000, 2013GB104002, 2014GB107000, 2014GB108000), and the China-Korean Joint Research Program (No. 2012DFG02230)

Abstract

On HL-2A, two different injections (supersonic molecular beam injection (SMBI) and pellet injection (PI)) are used to mitigate edge localized mode (ELM)-filament convective transport. The changes of their characteristics are studied in this paper. A high spatiotemporal resolution probe shows there are many similar phenomena, and the filament density amplitude and radial velocity are both suppressed. Our statistical results indicate that: the velocity suppression comes from the decrease of filament density and temperature; the transient particle and heat fluxes drop strongly; and long-range correlation along a magnetic flux surface also decreases, when the electron-ion collisionality increases significantly, which may have a role on the filament parallel current during ELM mitigation.