Dressed test particles, oscillation centres and pseudo-orbits

TL;DR

This paper introduces a semi-analytical method for accurately computing the dielectric screening effects around a moving test particle in plasma, avoiding approximations and applicable to various velocities.

Contribution

It presents a general, approximation-free numerical approach for calculating dressed potentials in plasma, connecting quasiparticle concepts with oscillation-centre and pseudo-orbit formalisms.

Findings

Method accurately computes dressed potentials for different particle velocities.

Results demonstrate the method's efficiency and precision.

Connections made between plasma fluctuation spectra and quasiparticle models.

Abstract

A general semi-analytical method for accurate and efficient numerical calculation of the dielectrically screened ("dressed") potential around a non-relativistic test particle moving in an isotropic, collisionless, unmagnetised plasma is presented. The method requires no approximations and is illustrated using results calculated for two cases taken from the MSc thesis of the first author: test particles with velocities above and below the ion sound speed in plasmas with Maxwellian ions and warm electrons. The idea that the fluctuation spectrum of a plasma can be described as a superposition of the fields around \emph{non-interacting} dressed test particles is an expression of the quasiparticle concept, which has also been expressed in the development of the oscillation-centre and pseudo-orbit formalisms.