SIMulator & Postprocessor for free electron Laser EXperiments

Getting Started with SIMPLEX

A simple instruction to perform FEL simulations with SIMPLEX is introduced in the followings.

Step 1: Open or create a parameter file

Open an existing parameter file that contains all the information necessary to perform a simulation. You can also create a new parameter set by executing [File]-[Create New] command.

Step 2: Edit the Parameters

You will find tabbed windows on the SIMPLEX main window. Click any tab to view or edit the parameters as you like. The meanings of the parametes can be found in the reference manual, which can be opened by execugint [Help]-[Reference Manual] command. The parameters, such as the wavelength, electron-beam size,FEL (or Pierce) parameter, gain length, and saturation power, are calculated with the current settings and indicated in the right-hand panel on the main window.

Step 3: Counfigure Focusing Magnets and Twiss Parameters

If you changed the accelerator or undulator parameters such as the electron energy and the undulator length, it is recommended to configure the focusing parameters. Click the "Focusing" tab to see the current settings. You will find the twiss parameters at the entrance of the undulator and the arrangement of the focusing magnets. In order to see the betatron functions with the current settings, execute [Configuration]-[Plot betatron Functions] command. Change the focusing paramters untill the beta functions become desirable. For details about optimization of parameters, refer to the reference manual.

Step 4: Counfigure Simulation Controls

It is also recommended to edit parameters concerning the simulation control. Click the "Controls" tab to see the paramters for the simulation control, with which you can specify the type of simulation (time-dependent or time-independent), the range of the electron bunch (slice location), the number of macroparticles, and so on. Also, the parameters related to dumping the simulation output data should be specified. For time-dependent simulatons, the dump file size may be quite huge: take care so that it does not exceed the memory of the hard disk. An approximarte value of the file size is indicated in the window. Note that if the time-independent simulation is selected, the power of the seeding light (specified in the "Seed" tab window) should be a positive number. Otherwise, no FEL gain is obtained.

Step 5: Start Simulation

After all the parameters are set up, execute [Run]-[Start Calculation] command to start a simulation. A dialog box will pop up to enter a data name. All the simulation results are save to files "****_average.dat" and "****.spx", where "****" is the data name. In the former file, quantities averaged over the electron bunch (for time-independent simulation, those in the single slice) are saved in an ascii format. In the latter file, all the values such as the complex amplitude of the radiation and electron position in the 6-dimensional space are saved in a binary format. The so-called radiation power-growth curve is saved in the "****_average.dat" and the graphical plot is shown in a window that pops up after completion of the simulation.

Step 6: Post-processing

The simulation results saved in "****.spx" can be visualized. To do so, execute [View]-[Visualization Panel] command to open the "Visualization Configuration Window". Specify the item and method for visualization in this window and retrieve the data from the data file. For details refer to the reference manual.