First Lasing of the CAEP THz FEL facility Driven by a Superconducting Accelerator

China Academy of Engineering Physics terahertz free electron laser (CAEP THz FEL, CTFEL) is the first THz FEL oscillator in China, which was jointly built by CAEP, Peking university and Tsinghua university. The stimulated saturation of the CTFEL was reached in August, 2017. CTFEL consists of a GaAs photocathode high-voltage DC gun, a superconducting RF linac, a planar undulator and a quasi-concentric optical resonator. The terahertz lasers frequency is continuously adjustable from 2 THz to 3 THz. The average power is about 20W and the micro-pulse power is more than 0:3MW.