zcl-maker / Quill

Quill is a 3D QED-PIC code for simulations of interaction of electromagnetic radiation and particles with plasmas with QED effects such as gamma photon radiation and electron–positron pair production.

QUILL: 3D QED particle-in-cell code

QUILL (simulator for QUantum effects in Intense Laser-pLasma interactions) is a fully three-dimensional parallel particle-in-cell (PIC) code developed at the Institute of Applied Physics RAS, Nizhny Novgorod, Russia. To our knowledge, it was the first PIC code with implementation of the Monte Carlo QED approach to investigate the development of electron–positron cascades.

The code is able to model the following processes using the Monte Carlo technique:

• photon emission by an electron in the strong field, with radiation reaction effects;
• electron–positron pair creation from gamma photons (Breit–Wheeler process).

The Maxwell solvers implemented in the code are NDFX (the scheme used in A. Pukhov's VLPL code) and FDTD. The particles pushers implemented in the code use Vay or Boris scheme.

Dependencies

In order to build and run Quill, the following dependencies are required:

• C++ compiler with C++11 support;
• Make;
• MPI implementation;
• Python3 interpreter (optional: NumPy and Matplotlib for data analysis).

Quill is developed and tested on Linux with the use of g++ and clang++ compilers and OpenMPI.

Build

To build Quill, run make all in the quill3d folder.

Note: Running make without target all does not build the required chameleon package. Use make without targets only if chameleon is already built.

By default, the build process invokes mpicxx which should automatically provide necessary include and library paths for the compiler and linker. Use the CXX environment variable to override this behavior.

When OpenMPI is used, the OMPI_CXX environment variable can be used to select the C++ compiler, e.g.

OMPI_CXX=clang++ make all

Input files

Input files for Quill should be placed in the quill3d-conf folder. An input file must begin with the quill.conf prefix.

Example input files can be found in the quill3d-conf/examples folder. All possible parameters in the input file are described in the quill.conf.example file.

Run

To run Quill, use the run.sh script from the quill3d folder and pass the name of the input file without the quill.conf prefix as a parameter. For example,

./run.sh .my-problem

will run Quill using the quill-conf/quill.conf.my-problem input file.

By default, run.sh relies on mpirun. Rewrite the script itself if different behavior is required.

The number of MPI threads is determined by the n_sr parameter in the input file and should never be explicitly set to a different value.

Note: In order to run Quill, a Python interpreter is required on all nodes; it is used to parse the input file.

Analyze results

Results can be graphically analyzed with the qplot Python package located in the quill3d/python folder. Refer to the documentation within the package itself. Documentation in IPython or Jupyter Notebooks/Lab can also be accessed using the ? command, e.g. qplot.density?

Low-level data reading is available in the resread package.

The qplot package depends on the matplotlib and numpy packages; resread depends only on numpy.