Design of rf conditioner cavities

Abstract

Theoretical studies are made of radio frequency structures which can be used to condition electron beams so as to greatly reduce the stringent emittance requirements for successful lasing in a free-electron laser. The basic strategy of conditioning calls for modulating an electron beam in the transverse dimension, by a periodic focusing channel, while it traverses a series of rf cavities, each operating in a TM210 mode. In this paper, we analyze the cavities both analytically and numerically (using MAFIA simulations). We find that when cylindrical symmetry is broken the coupling impedance can be greatly enhanced. We present results showing various performance characteristics as a function of cavity parameters, as well as possible designs for conditioning cavities.

Simulation analysis of the effect of beam pipes and multi-mode competition in the standing-wave free-electron laser two-beam accelerator

“…Effect of beam pipes on the operating-mode field in an ideal FEL cavity MAFIA [15] is extensively used to calculate rf cavities in the accelerator community, but typically only those cavity modes with fairly small mode indices are involved [16]. In the SWFEUTBA configuration, however, the FEL interaction cavity is rather long and it contains up to 96 half wavelengths [12].…”