ECRH by finite band width free‐electron laser

Electron cyclotron resonance heating (ECRH) when an intense microwave field with GW power level is split into slight different frequency fields is investigated. Due to the strong electric field, the phase space island can be overlapped even if k∥(parallel wave number)≂0 provided that each frequency is pertinently chosen. The island overlapping in the phase space induces the stochastic electron motion and pumps up thermal electrons into the higher energy state. Furthermore, the related electron phase randomization enhances the ratio of the heated particle for an initial distribution.