Speaker
Description
The Korea Atomic Energy Research Institute has developed a 5-MeV compact microtron accelerator to construct a high-power terahertz (THz) free electron laser (FEL) for field use. Good quality electron beam is essential for generating strong THz laser beam. Optimizing the electron beam was a priority for ensuring the performance and stability of the final THz FEL beam. The compact microtron accelerator has components that are difficult to adjust. The controllable factors are the RF power, microtron magnetic field strength, and the relative position between microtron RF cavity and beam extractor. We found that part of electron beam hit the exit gate of the extractor. To solve this problem, an adjustable guide line for the RF assembly including a magnetron, waveguide components and cavity was installed to stably relocate the cavity for optimizing the beam extraction to an FEL beamline. The beam exiting the microtron inevitably has large dispersion due to 180-degree rotation. Using ASTRA code, we determined the strengths of the quadrupole magnets in the beamline to minimize the dispersion after bending the beam 90 degrees. After bending, electron beam enters a strong electromagnet undulator and waveguide-mode resonator. After accurately characterizing the beam and undulator specifications, we plan to inject the electron beam into the undulator to attempt THz laser oscillation.
