EFFECT OF LONGITUDINAL MOMENTUM SPREAD IN ION-RIPPLE LASER

Using kinetic coupling mode theory of three waves, the effect of longi tudinal momentum spread in ion-ripple laser (IRL), which is an advance d new scheme to generate tunable-coherent radiation with frequency ran ging from microwaves to x-rays, is investigated. For a Gaussian distri bution in beam longitudinal momentum, the results show that the growth rate of IRL falls of rapidly with increasing momentum spread, and the momentum spread causes linear damping of beam space-charge wave, weak ening the beam-radiation mode coupling and lowering the output radiati on frequency apart from broadening the radiation spectrum. The dispers ion relation and phase matching conditions are also obtained.