Oversized Electrodynamic Systems for Powerful Long-Pulse Sub-THz/THz Band FEL: Simulations and “Cold” Tests

Project of sub-THz/THz band FEL driven by induction linac “LIU” 5 - 20 MeV / 2 kA / 200 ns is under development in collaboration between BINP RAS (Novosibirsk) and IAP RAS (N.Novgorod) and aimed to achieve ultra-high (sub-GW to GW level) radiation power in this frequency range. In order to provide stable narrow-band generation regime in the strongly-oversized oscillator, we elaborate two types of electrodynamic systems: (1) advanced Bragg resonators based on coupling of quasi-cutoff and propagating waves and (2) quasi-optical resonators of the Talbot-type. Design of these resonators, their simulations and “cold” test results are presented, state of the project is discussed.