Avalanche Phenomenon of Runaway Electrons During Additional Fueling

During pellet injection and supersonic molecular beam injection, we have observed the increase of electron density and the enhancement of hard x-ray radiation, but the runaway electrons normally decrease without additional fueling when the density of plasma increases. This phenomenon may come from synergetic effects of Dreicer and avalanche runaway electrons. The experimental results are consistent with the calculation based on the theory of avalanche runaway in the HL-1M Tokamak.