Enhancement of runaway avalanche during LHCD and fishbone instability

Certain amount of highly energetic runaway electrons in a plasma can knock out bulk electrons through large angle Coulomb scattering, and these secondary electrons can be effectively accelerated to become runaway electrons by lower hybrid current drive (LHCD). These runaway electrons can be returned to the plasma by positive feedback, and this process leads to an avalanche effect. During this process, some secondary electrons with larger poloidal momentum or a part of energetic electrons driven by LHCD are trapped in the banana trajectory. When certain magnetic oscillations are resonant with the electrons trapped in the magnetic island, the fishbone instability appears