Fueling Performance of Supersonic Molecular Beam Injection on the J-TEXT Tokamak

A supersonic molecular beam injection (SMBI) system was developed on the J-TEXT tokamak. With SMBI fueling, a continuous electron density increase was successfully achieved when multiple-pulse injection was employed. A steeper density profile was observed during the penetration process. A high fueling efficiency, between 20% and 45%, was obtained in limiter/ohmic discharges, suggesting that SMBI is a superior fueling method. SMBI efficiency decreased with increasing background electron density. Analyses of the penetration process with a H α array and a CCD camera suggest the ionization mainly concentrates in the SOL and plasma edge region.