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Warwick-Plasma / epoch

Particle-in-cell code for plasma physics simulations
https://epochpic.github.io
GNU General Public License v3.0
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Use a more efficient method for sampling from Maxwell-Jüttner distributions #60

Open keithbennett opened 3 years ago

keithbennett commented 3 years ago

In GitLab by Keith Bennett (@keithbennett) on 31 May 2019, 16:48 (GitLab issue GL#2030)

Description

The current method just uses accept/reject. There are more efficient methods available.

Links / references

Zenitani, S. (2015). Loading relativistic Maxwell distributions in particle simulations. Physics of Plasmas, 22(4), 042116. http://doi.org/10.1063/1.4919383

Schnittman, J. D., & Krolik, J. H. (2013). A MONTE CARLO CODE FOR RELATIVISTIC RADIATION TRANSPORT AROUND KERR BLACK HOLES. The Astrophysical Journal, 777(1), 11. http://doi.org/10.1088/0004-637x/777/1/11

Melzani, Mickaël, Winisdoerffer, Christophe, Walder, Rolf, Folini, Doris, Favre, Jean M., Krastanov, Stefan, & Messmer, P. (2013). Apar-T: code, validation, and physical interpretation of particle-in-cell results. A\&A, 558, A133. http://doi.org/10.1051/0004-6361/201321557

keithbennett commented 3 years ago

In GitLab by Christopher Brady (@csbrady-warwick) on 31 May 2019, 17:01

A possible caveat but both of those methods are for the isotropic Maxwell-Juttner distribution and because of the Lorentz gamma factor you can't sample each component separately. Anisotropic Maxwell-Juttner distributions are perfectly meaningful (Livadotis (2016) Modeling anisotropic Maxwell–Jüttner distributions: derivation and properties http://doi.org/10.5194/angeo-34-1145-2016 ) so removing the possibility of sampling them would be quite a serious change. It might be possible to modify the algorithms for anisotropic distributions but that is a bigger job.

keithbennett commented 3 years ago

In GitLab by Keith Bennett (@keithbennett) on 31 May 2019, 17:05

changed the description