Key Technologies of a Terahertz Source Based on Free Electron Lasers

In this paper some key technologies of a THz source based on free electron lasers are discussed. In order to yield exceptionally high quality THz radiation, electron guns are expected to create high-brightness and short-pulse beams, and the normalized rms beam emittance and longitudinal rms emittance should be low. At the same time, a linear accelerator and an undulator should be designed carefully. The electron beam through the high gradient linac and the undulator is discussed.