Velocity-space compression from Fermi acceleration with Lorentz scattering

J. C. Waybright, M. E. Mlodik, N. J. Fisch

Research output: Contribution to journalArticlepeer-review

1 Scopus citations


The Fermi acceleration model describes how cosmic ray particles accelerate to great speeds by interacting with moving magnetic fields. We identify a variation of the model where light ions interact with a moving wall while undergoing pitch angle scattering through Coulomb collisions due to the presence of a heavier ionic species. The collisions introduce a stochastic component which adds complexity to the particle acceleration profile and sets it apart from collisionless Fermi acceleration models. The unusual effect captured by this simplified variation of Fermi acceleration is the nonconservation of phase space, with the possibility for a distribution of particles initially monotonically decreasing in energy to exhibit an energy peak upon compression. A peaked energy distribution might have interesting applications, such as to optimize fusion reactivity or to characterize astrophysical phenomena that exhibit nonthermal features.

Original languageEnglish (US)
Article number015207
JournalPhysical Review E
Issue number1
StatePublished - Jan 2022

All Science Journal Classification (ASJC) codes

  • Condensed Matter Physics
  • Statistical and Nonlinear Physics
  • Statistics and Probability


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