Effects of electron beam temperature on radiation growth rate in a realistic helical wiggler with ion-channel guiding

We study the effects of electron beam parameters such as electron beam temperature and Lorentz relativistic factor (or electron energy) on growth rate in a realistic (three-dimensional) helical wiggler free-electron laser with ion-channel guiding. A generalized dispersion relation is derived by considering the interaction between the radiation fields and electron beam when the effects of electron beam self-fields are taken into account. The growth rate is then calculated, and it is found that, for group I orbits, there is an optimum value for electron beam density at which the growth rate goes to its maximum. Also, there is an optimum value for Lorentz relativistic factor. The effect of beam temperature is also investigated, and it is shown that the growth rate decreases considerably as beam temperature increases.