Saturation in ion-channel free electron laser with electromagnetic wiggler

The effect of ion-channel guiding on saturation mechanism of a single pass free electron laser with electromagnetic wiggler is studied numerically. By using equations of motion of electron beam and field equations, a set of coupled nonlinear differential equation is derived in slowly varying envelope approximation. The electron beam propagates with a relativistic velocity, ions are assumed immobile and slippage is ignored. A comparison is made between the result of propagation of the electron beam in an electromagnetic and magnetostatic wiggler. Numerical simulations are performed with and without ion channel, for electromagnetic wiggler. Calculations are made for the saturation length, bunching parameter and output power.