Energy and momentum conservation upon reflection of a solitary pulse in a bounded magnetized plasma

TL;DR

This paper investigates how energy and momentum oscillate during the reflection of magnetosonic pulses in bounded magnetized plasmas, revealing radiation effects and momentum transfer mechanisms through analytical models and simulations.

Contribution

It introduces a detailed analysis of energy and momentum conservation during pulse reflection, highlighting oscillations, radiation effects, and momentum transfer mechanisms in magnetized plasma slabs.

Findings

Energy and momentum oscillate during reflection.

Radiation to and from vacuum causes oscillations.

Partial reflection leads to energy and momentum losses.

Abstract

When the nature of a magnetosonic pulse propagating in a bounded magnetized plasma slab is successively transformed from compression to rarefaction and vice-versa upon reflection at a plasma-vacuum interface, both the energy and the longitudinal electromagnetic (EM) momentum of the plasma-pulse system are found to oscillate between two states. Simple analytical models and particle-in-cell simulations show that these oscillations are associated with EM radiation to and from the surrounding magnetized vacuum. For partial reflection supplemental losses in total pulse energy and mechanical momentum are identified and shown to follow respectively Fresnel's transmission coefficients for the energy and the magnetic perturbation. This mechanical momentum loss upon partial reflection is traced to the momentarily non-zero volume integrated Lorentz force, which in turn supports that mechanical and EM momentum transfers are respectively associated with the magnetic and electric parts of the momentum flux density.