NORSE -- NOn-linear Relativistic Solver for Electrons

Installation and usage

NORSE is a Matlab program. No compilation or external libraries are required, except that runawayRegionMode = 3 requires Matlab's Curve Fitting Toolbox. A detailed description of the usage, available settings, and various output quantities is given in the file NORSE.m in the folder @NORSE. See also the files in the examples folder. Examples of how to access and process the output are given in the various methods of the Plot class (see Plot.m in @Plot).

To use NORSE in a MATLAB script, either add the src directory permanently to your MATLAB path, or for the current session by running

addpath('/path/to/NORSE/src/')

(or by putting this line at the top of your MATLAB script).

NORSE files

Each folder starting with a @ under src contains the files for a class with the corresponding name (without the @). Inside the folder, the file with the same name as the folder is the main file of that class. The classes are:

• NORSE

  Main class for performing a NORSE calculation.

• Grid

  Class that describes the finite-difference grid in a NORSE calculation, and associated quantities such as finite-difference derivatives. Also contains various methods for manipulating the grid.

• TimeAdvance

  Abstract class that handles the advancement of the NORSE system in time.

  • TAAdaptive

    Subclass that implements an adaptive-time-step time-advancement scheme

  • TADirect

    Subclass that advances the system using direct matrix inversion (LU)

  • TAInductiveE

    Subclass that solves for both the distribution and the electric-field evolution, self-consistently

  • TAIterative Subclass that advances the system using indirect matrix inversion (GMRES). This is usually faster than the direct approach

• Potentials Handles the calculation of the potentials of the Braams & Karney collision operator.

• CollisionOperator

  Abstract class that describes the electron-electron and electron-ion collision operators, as well as artificial damping at the boundary of the momentum grid.

  • CNonLinear

    Sub class that implements the nonlinear realativistic Braams & Karney operator.

• HeatSink

  Class that describes the heat sink in NORSE as well as related quantities such as the contribution to the source magnitude from various effects.

• ParticleSource

  Class that describes the particle source/sink needed to perform changes to the electron density.

• TimeDependentParameter

  Class for defining convenient time-dependent quantities.

• Plot

  Implements various plots and visualizations for the NORSE solution or its properties.

Example files

These are found in the examples folder.

• SimpleNORSERun.m

  Shows how to perform a simple NORSE run, using default settings.

• AdvancedNORSERun.m

  Shows an example of a more involved NORSE run, including how to change settings, use time-dependent parameters, and continue the calculation after it has finished.

• outputSimple.m

  The expected final distribution when running SimpleNORSERun.m.

• outputAdvanced.m

  The expected final distribution when running AdvancedNORSERun.m.

Author

NORSE was originally written by Adam Stahl as part of his PhD, and is today maintained by the Chalmers Plasma Theory group. For details about current developers, please see the DEVNOTES.md.

References

When publishing results obtained with NORSE, please cite the official NORSE paper:

[1] Stahl A., Landreman M., Embréus O. and Fülöp T. 2017 Comput. Phys. Comm. 212 269-79

Other publications using NORSE:

[2] Stahl A. 2017 PhD Thesis Chalmers University of Technology. Available online.