Numerical Studies on Tunable Coherent Radiations with a Laser-plasma Accelerator*

Generation of tunable coherent radiation is numerically investigated via the two-dimensional particle-in-cell (2DPIC) code developed by UNIST [1] and SIMPLEX developed by Spring-8. The electron beams can be produced by the laser-driven wakefield acceleration technique. The electron beam energy can be easily adjusted between 450 MeV and 800 MeV with a tapered density plasma on the order of 1×10 cm while the driving laser power is fixed, and the high-energy electron beams can be sent through the undulator arrays for the coherent light emission. The energy-controllable electron bunches can provide an opportunity to control the radiation wavelength with the fixed gap undulators. For the tapered density profile, a capillary cell with two gas inlets can be used. In this paper, we show some simulation and numerical research results regarding these issues, which reveal the possibility for a tunable light source in the soft X-ray regime.