Runes2P

The name stands for RUNaway Electron Solver in 2 momentum (P) dimensions: the electron distribution is resolved in the magnitude of the momentum and in its pitch.

Runes2P

Runes2P solves the relativistic Fokker-Planck equation of the electrons of a cylindrical plasma together with the fluid quantities that couple to it. The unknowns are laid out by an UnknownLayout: distribution functions on a KineticGrid, whose momentum grid may differ between radii, radial profiles and scalars. Each unknown has an Equation built from EquationTerms. The equations form an EquationSystem, $M \, \mathrm{d}u/\mathrm{d}t = \mathrm{rhs}(u, t)$. integrate advances it with backward Euler steps, or BDF2 steps with StepController, each solved by Newton's method (NewtonSolver), and write_output writes the result.

Citing and acknowledgements

These are requests, not conditions of the licence.

• Parts of Runes2P are ported from DREAM and compared with it. Please cite the DREAM paper: M. Hoppe, O. Embréus and T. Fülöp, Computer Physics Communications 268, 108098 (2021), doi:10.1016/j.cpc.2021.108098.
• For hydrogen and its isotopes, neon and argon, the :chianti form of ionization_cross_section uses the fit parameters of the CHIANTI atomic database, version 11.0.2. CHIANTI is a collaborative project involving George Mason University, the University of Michigan (USA), the University of Cambridge (UK) and NASA Goddard Space Flight Center (USA). Work that uses these data should cite:
  • K. P. Dere et al., Astronomy and Astrophysics Supplement Series 125, 149 (1997), doi:10.1051/aas:1997368,
  • R. P. Dufresne et al., The Astrophysical Journal 974, 71 (2024), doi:10.3847/1538-4357/ad6765,
  • for the ionization data, K. P. Dere, Astronomy and Astrophysics 466, 771 (2007), doi:10.1051/0004-6361:20066728.
• The ADF11 rate coefficients that read_adas reads are taken from OPEN-ADAS (https://open.adas.ac.uk) under its terms and conditions. For H, D and T, every rate coefficient except charge exchange comes from the high-density files of DREAM's repository instead. No ADAS data file is distributed with Runes2P. ADAS: H. P. Summers, The ADAS User Manual, version 2.6 (2004), https://www.adas.ac.uk.
• The ionization energies of IONIZATION_ENERGIES are those of the NIST Atomic Spectra Database (Kramida, Ralchenko, Reader and the NIST ASD Team, doi:10.18434/T4W30F), through DREAM's table.
• NIST ESTAR is the reference of the radiative stopping power that the docstring of CollisionSettings names. ESTAR: M. J. Berger, J. S. Coursey, M. A. Zucker and J. Chang, NIST Standard Reference Database 124 (2017), doi:10.18434/T4NC7P.
• The DREAM reference data of the tests come from DREAM's public examples and from synthetic cases, generated with DREAM release v26.5 and DREAM's public branch boltzmann-eqterm. A further set holds GSL 2.8's bicubic interpolation as DREAM uses it, on a synthetic table (see Reference data).

The licences of the code and data that Runes2P builds on are in the file THIRD_PARTY_NOTICES.md of the repository.

Installation

Runes2P is added from its repository, as described on the page Getting started.

Four parts are package extensions, enabled by loading their packages next to Runes2P (see Extensions):

• HDF5: the output files and checkpoints (write_output, read_output),
• SciMLBase: the SciML form of an equation system (ode_function),
• Interpolations: interpolators of Interpolations.jl as radial profiles,
• Pardiso: the linear solver MKLPardiso, Intel MKL PARDISO.

Questions and bug reports go to the issue tracker of the repository, https://github.com/osrep/Runes2P.jl/issues.

Map of the pages

• Getting started: installation, a first run with the examples, the units of the inputs, the settings of a run and its output files.
• Model and numerics:
  • Unknowns and the equation system: the unknown layout, equations and terms, the equation system and its pairing checks.
  • Grids: momentum, pitch and radial grids, the hot-tail and runaway grids and their interface.
  • Collision models: the Fokker-Planck operator, screening, bremsstrahlung, synchrotron, knock-on and field-particle collisions.
  • Atomic data and ionization: ADAS rates, the kinetic ionization cross sections, radiation.
  • Energy and current balance: the energy of the electrons, the energy transfer between the distributions, conductivity and induction.
  • Positivity and flux limiters: the interpolation schemes of the advection, the limiters, the lower limits of the Newton step.
  • Time stepping and solvers: backward Euler, the step controllers, Newton, the linear solvers, checkpoints and the stop.
  • Output files: the HDF5 output and checkpoint format, reading and joining segments.
• Choices of this package: the values and defaults that are choices of this package, with their reasons.
• Performance and accuracy: the guidelines for cost and accuracy, the hot paths, the linear solvers and the measurements against DREAM.
• Comparison with DREAM: the features of DREAM and their state in Runes2P, the departures.
• The disruption case: the comparison of Runes2P with DREAM in DREAM's disruption case, at the size of the tests and in two whole quenches at full size.
• Reference data: the reference sets of the tests and how to regenerate them.
• API:
  • Overview: how the API reference is organized and built.
  • Grids, Physics, Operators, Equation system, Solvers and runs: the docstrings by category.
  • Extensions: the docstrings of the package extensions.