Analysis of the effects of plasmas and beam slippage in optical klystron FEL devices

We examine here the effects of plasmas and beam slippage on the gain of an optical klystron (OK) free electron laser (FEL) device under the influence of a weak guiding magnetic field and background plasma. The beam energy spread decreases with background plasma density nop and increases with beam plasma density nob. The maximum gain (Gmax) scales proportional to nop2. The beam slippage phase Δψ scales directly to five power of relativistic factor γ0 and one half power to nob.