Supersonic molecular beam injection (SMBI)

a new fuelling method

was first proposed and demonstrated on the HL-1 tokamak in 1992

and successfully developed and used in HL-1M (modified from HL-1) and HT-7 superconducting tokamak. The characteristics of the beam injection are electron density peaking and hollow profile of electron temperature. The increase of the rotation velocity of poloidal plasma flow results in the edge plasma disturbance eliminating and plasma energy confinement improvement. The fuelling efficiency of SMBI is increased to twice as much as that for gas puffing

whereas the particle retention on the surface is reduced. Recently new results of SMBI experiments were obtained by increasing the gas pressure

and the hydrogen clusters within the beam were found to play an important role in the deeper injection. It was also shown that injected particles could penetrate into the core region of the HL-1M plasma

which results in a stair-shaped electron density increment

just as the behavior of ice pellet injection. These results prove effectiveness of SMBI as a promising fuelling tool for stead-state operation of great-size tokamak or stellarator.