Development and Testing of a 3.9 GHz Third Harmonic Superconducting RF System at Fermilab (original) (raw)

A 3.9 GHz third harmonic Superconducting RF (SRF) system was proposed to increase the peak bunch current of the particle beam and to linearize the accelerating voltage acting on the electrons within a bunch in the longitudinal phase space for the Free Electron Laser in Hamburg (FLASH) user facility in Germany. Fermilab, as part of the FLASH collaboration, participates in developing and testing the 3.9 GHz third harmonic SRF system. Theoretical consideration, design and simulation, and high-power testing of the 3.9 GHz SRF components including superconducting cavities and main couplers will be presented in this paper.