A slow wave free-electron laser in a longitudinal wiggler field

Linearized Vlasov-Maxwell equations are solved to obtain the growth rate of free electron laser instability from a tenuous relativistic electron beam propagating in a partially dielectric loaded waveguide immersed in combined axial and longitudinal wiggler magnetic fields. The instability appears via cyclotron resonance interactions for wave perturbations very close to w-kV/sub z/-w/sub c/=nk/sub 0/V/sub Z/ where n is the general harmonic number. For n=0, the gain is similar to a slow wave cyclotron amplifier. For n>or=1, the growth rate is substantially larger than the standard slow wave free electron laser scheme utilizing a transverse wiggler field.<
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