Simulations of Seeding Options for THz FEL at PITZ

A THz FEL is under commissioning at PITZ as a proof-of-principle experiment for a high power and high repetitionrate THz source and as an option for THz-driven experi-ments at the European XFEL. Some of these experimentsrequire excellent coherence and CEP stable THz pulses. InSASE regime, the coherent properties of the FEL radiationare limited. A seeding scheme can be used instead of SASEto improve the coherent properties and shot-to-shot stability.Several options for seeding are considered in simulation forthe THz FEL at PITZ: external laser pulse, pre-bunched elec-tron beam, energy modulated electron beam and additionalshort spike on top of a smooth beam profile. The improve-ments over SASE in energy, spectral and temporal stabilityof the THz pulse are presented