SIMPLE: Symplectic Integration Methods for Particle Loss Estimation

SIMPLE computes statistical losses of guiding-center orbits for particles of given mass, charge and energy from the volume of 3D magnetic configurations. Orbits are traced via a symplectic integrator [1,2] that guarantees conservation of invariants of motion within fixed bounds over long integration periods. A classifier based on Poincarè plots [1] allows for accelerated prediction for confinement of regular (non-chaotic) orbits.

The main focus of SIMPLE is to make computation of fusion alpha particle losses fast enough to be used directly in stellarator optimization codes. For that reason currently 3D configurations with nested magnetic flux surfaces are supported based on a VMEC equilibrium file in NetCDF format, and orbits are computed without taking collisions into account.

The code is free to use and modify under the MIT License and links to Runge-Kutta-Fehlberg routines in SRC/contrib/rkf45.f90 from https://people.sc.fsu.edu/~jburkardt/f_src/rkf45/rkf45.html under the GNU LGPL License as well as MINPACK in SRC/contrib/minpack.f90 under the according license.

When using this code for scientific publications, please cite the according references:

[1] C. G. Albert, S. V. Kasilov, and W. Kernbichler, Accelerated methods for direct computation of fusion alpha particle losses within stellarator optimization. J. Plasma Phys. (forthcoming, 2020)

[2] C. G. Albert, S. V. Kasilov, and W. Kernbichler, Symplectic integration with non-canonical quadrature for guiding-center orbits in magnetic confinement devices. J. Comp. Phys 403, 109065 (2020), https://doi.org/10.1016/j.jcp.2019.109065, preprint on https://arxiv.org/abs/1903.06885