Effects of self-fields on dispersion relation in a helical wiggler with ion-channel guiding

The effects of self-fields on dispersion relation in a helical wiggler free-electron laser with ion channel guiding are investigated. An equation for dispersion relation showing coupling of space-charge and electromagnetic waves in the presence of self-fields is derived. Numerical solutions of the dispersion equation are used to study growth rate. It is shown that for helical wiggler and ion-channel guiding the growth rate decreases due to the self-fields.