Compact Waveguide-mode Terahertz Free-electron Lasers in KAERI

概要

We have developed compact terahertz (THz) free electron lasers (FELs) by using classical microtrons driven by magnetrons. The main advantages of the magnetron-driven microtron are compactness, cost-effectiveness, and high beam quality (relatively low emittance and energy spread). However, the peak current of the microtron is less than 1 A (~10 pC for 15 ps bunch duration) and it is not easy to get enough gain for FEL operation with the beam. To enhance the interaction between electrons and electromagnetic waves in the FEL oscillators, we used a parallel-plate waveguide for our first THz FEL (100-300 micro-meter light with linear polarization) and a circular waveguide for the second THz FEL (400-600 micro-meter, circular polarization). I will introduce some technical points for the waveguide-mode FEL oscillators, for example, mode size and loss in the waveguides, undulators, outcoupling of the radiation, applications, and so on.