Microbunching Free Electron Laser

Tabletop plasma laser accelerators require bunched electron beams as inputs. An ideal source for this bunched beam would be a free electron laser that operates at terahertz frequencies. The addition of a terahertz waveguide to the free electron laser would permit efficient bunching with low input power. Therefore, this project will develop, test, and build two bunching undulator systems with THz waveguides, ancillary magnets, and fully turn-key operation. Phase I showed that microbunching undulators in the THz range are technically feasible and can be built in a cost effective way. In particular, Phase I involved a magnetic analysis of the microbunching undulator, an analysis of THZ waveguide impact on undulator design, and an engineering design analysis of the microbunching undulator. Phase II will: (1) refine the magnetic analysis based on engineering details; (2) engineer, design, and build two undulators, chicanes and THz waveguides for future research; and (3) test both the short and long THz waveguides with the 60 cm and 2 meter microbunching undulators. These tests will entail performing beam propagation measurements and comparing resonant FEL amplification with theoretical predictions. Commercial Application and Other Benefits as described by the awardee: The new free electron laser would be a source of high-power terahertz radiation with many applications including future DOE accelerators, the U.S. Navy, and the Department of Homeland Security. There are no commercial suppliers of these microbunching free electron lasers.