Key issues in the design of a two-stage FEL

A number of key issues for the design of a two-stage FEL with a cylindrically symmetric quasioptical cavity are investigated. Designs for long- and short-wavelength cavities are presented. Techniques for designing the wiggler injection optics and determining the effect of finite beam size on laser gain and bandwidth are described. An electrostatic accelerator conceptual design that could permit continuous operation of the two-stage system is also presented.