Analysis of wakefield effects on the operation of an energy-recovering superconducting linear accelerator

Abstract

An energy-recovering superconducting linear accelerator is being developed fur a high-power infrared free-electron laser (FEL). The design value of the maximum beam current circulating in the superconducting cavities is 50 mA. In such a high-current accelerator, the wakefield excited by the bunches passing through the cavities can induce unstable operation of the accelerator. The effects of the wakefield on the accelerator operation are analyzed for successful lacing of the FEL. The beam quality degradation, the starting current of tire beam breakup, and the power loss to the higher-order mode coupler are calculated analytically and numerically. It is found that the accelerator can be operated at the maximum current without having a severe problem caused fey the wakefield.