ENERGY STABILITY IN A HIGH AVERAGE POWER FEL

摘要

Recirculating, energy-recovering linacs can be used as driver accelerators for high power FELs. Instabilities which arise from fluctuations of the cavity fields are investigated. Energy changes can cause beam loss on apertures, or, when coupled to M_(56), phase oscillations. Both effects change the beam induced voltage in the cavities and can lead to unstable variations of the accelerating field. Stability analysis for small perturbations from equilibrium is performed and threshold currents are determined. Design strategies to increase the instability threshold are discussed and the high average power FEL proposed for construction at CEBAF is used as an example.