Abstract

A number of physics issues are relevant to the design of a high extraction efficiency wiggler for a free-electron laser (FEL) oscillator. The physics issues we address here are the following: (1) the balance of small-signal gain with maximum extraction efficiency when the wiggler length is constrained; (2) degradation of the electron extraction efficiency with the onset of the sideband instability and the use of corrective frequency filtering techniques to suppress the sideband; (3) reduction of efficiency due to the structure of the electron micropulse and that due to cavity length detuning; and (4) 3-D effects such as electron-beam emittance, focusing and refractive effects, misalignments, and the self-consistent FEL resonator solution with the electron beam present. We have developed several numerical models with increasing complexity to isolate and address the above physics issues. Each of these models is described in the following summary of the procedure we use to design a wiggler.

© 1986 Optical Society of America