FEL/Duke University, Durham, North Carolina
High repetition rate linacs and ERLs are preferred accelerators to drive high power FELs in the kW to hundreds of kW region. The storage ring FEL, given its well-known extracted power limit, has not been considered as a high power photon source. A high-intensity Compton gamma source requires a high-power photon source, which can be made available inside an FEL resonator. The Duke storage ring FEL has been developed as a high intracavity photon source for a world-class Compton gamma-ray source, High Intensity Gamma-ray Source (HIGS). Recently, the HIGS has reached a total flux of few 110 g/s at few to 10 MeV, enabled by a few-kW intracavity average power storage ring FEL. In this work, we report our recent experimental study of kW intracavity FEL operation in visible and near-IR wavelengths. In particular, we will present our novel approach to suppress wiggler power loading on the downstream FEL mirror using in-cavity apertures, a critical step to achieve kW intracavity power. We envision that this wiggler radiation power control technique be adopted by other high power resonator FELs driven by linacs and ERLs in their pursuit of further increasing the FEL power.
