minepoch

Minepoch is a mini-app version of the relativistic electromagnetic particle in cell (PIC) code EPOCH. Minepoch is designed to act both as a proxy-app for performance testing as well as a test-bed for PIC algorithm development. Minepoch contains the same core physics module as EPOCH, in which Maxwell's equations are solved on an Eulerian mesh, coupled to Lagrangian particles, as well as extensions to allow drift-kinetic particles to be treated.

Compiling the code

The code can be compiled using make, and an appropriately set compiler variable, for example:

$ make COMPILER=gfortran

The requirements are minimal, only a Fortran compiler and MPI are required to compile and run the code. The code is routinely run on both Linux and OS X, and tested with gfortran, but other compilers (e.g. make COMPILER=intel) ought to work.

Running the code

Minepoch is controlled using a Fortran namelist, which is read from Data/input.deck. The file Data/example_input.deck contains all the run-time configurable options and their default values. The code contains a number of predefined set-ups, which can be selected by changing the problem variable of the CONTROL namelist block.

A number of example input decks are included with the code:

• Data/two_stream.deck: A two-stream instability, run with the standard PIC algorithm
• Data/two_stream_substep.deck: The same two-stream instability, but with particle substepping enabled.
• Data/one_stream.deck: A 1D force-free problem illustrating the use of low-noise control-variates.
• Data/drift_kinetic.deck: An demonstration of the use of drift-kinetics in a quasi-1D setting.
• Data/em_wave.deck: A simple electromagnetic wave set-up in a vacuum. Also demonstrates use of the field probe diagnostic.

To run one of these problems the input deck must be copied to the correct location before running minepoch, for example:

$ cp Data/two_stream.deck Data/input.deck
$ ./bin/epoch3d

Analysing the results

As minepoch is primarily designed to test performance, only minimal diagnostics are included. These are written to Data/output.dat. Some example scripts for analysing the output can be found in the directory minepoch_py.

Further Details

• Information regarding the low noise PIC algorithm can be found in ExCALIBUR-NEPTUNE report 2047355-TN-03 (in Docs directory of this repository).
• Documentation on the advanced particle tracing routines (substepping and drift-kinetics) is included with the code. The document can be generated by running make docs.
• Although minepoch only includes a small subset of the functionality of the original EPOCH code, the user manual for EPOCH is included within each release.
• The EPOCH code paper contains a review of the core PIC algorithm used in minepoch and EPOCH.
• The original EPOCH code may be downloaded from the repository.

Any problems?

Please open an issue on the issue tracker.