SIMPLEX:

SASE (Self Amplified Spontaneous Emission) FEL simulation is carried out with the "sase.json" parameter file. After opening the parameter file, the location of the output file is specified first. Then, after checking the parameters, betatron functions are plotted as an example of pre-processing. Running "Start Simulation" command starts the simulation by invoking the solver ("simplex_solver_nompi" in this examle, because "Enable Parallel Computing" is disabled). After completing the simulation, various post-processing operations are done.

HGHG (High Gain Harmonic Generation) FEL simulation is carried out with the "hghg_mod.json" and "hghg_rad.json" parameter files. The former is to simulate the FEL process in the modulator with a long-wavelength seed laser. After the simulation with this file, the particle distribution in the E-t phase space is verified by the post-processor, and an optimum value for the longitudinal dispersion (R₅₆) is examined. Then, the FEL process in the radiator is simulated with the latter file by loading the output file of the former simulation, by specifying its file name in the file selection dialog.

Self-Seedd FEL simulation is carried out with the "self_seed.json" parameter file, in which SASE FEL radiation is monochromatized by Si(111) located at the 4-th undulator segment and works as a coherent seed pulse in the undulator segments afterward.

Repeat FEL simulations with the "sase.json" parameter file to optimize the undulator taper, by scanning a parameter "Base Linear Taper". In this example, five different taper values are examined, and the results (gain curves) are compared in the post-processor. Note that exporting the "Radiation Profile Data" is disabled to reduce the CPU time.

Showing how to operate the graphical plot to visualize the output data of the simulation and its post-processed results.