Energy transfer in binary collisions of two gyrating charged particles in a magnetic field

TL;DR

This paper presents a comprehensive classical perturbation theory for energy transfer during binary collisions of gyrating charged particles in magnetic fields, validated by numerical simulations across various regimes.

Contribution

It develops a second-order perturbation approach that accounts for all cyclotron harmonics and is valid for any magnetic field strength, extending previous models.

Findings

Perturbation theory agrees well with CTMC simulations for high velocities.

The method accurately describes energy transfer for finite, nonsingular potentials.

Strong collisions with large energy transfer are effectively modeled.

Abstract

Binary collisions of the gyrating charged particles in an external magnetic field are considered within a classical second-order perturbation theory, i.e., up to contributions which are quadratic in the binary interaction, starting from the unperturbed helical motion of the particles. The calculations are done with the help of a binary collisions treatment which is valid for any strength of the magnetic field and involves all harmonics of the particles cyclotron motion. The energy transfer is explicitly calculated for a regularized and screened potential which is both of finite range and nonsingular at the origin. The validity of the perturbation treatment is evaluated by comparing with classical trajectory Monte Carlo (CTMC) calculations which also allow to investigate the strong collisions with large energy and velocity transfer at low velocities. For large initial velocities on the other hand, only small velocity transfers occur. There the nonperturbative numerical CTMC results agree excellently with the predictions of the perturbative treatment.