Generation of wakefields by whistlers in spin quantum magnetoplasmas

TL;DR

This paper investigates how whistler waves can generate wakefields in dense, strongly magnetized spin quantum plasmas, revealing conditions for efficient particle acceleration driven by quantum and magnetic effects.

Contribution

It introduces a coupled nonlinear model showing how quantum and magnetic forces influence wakefield generation by whistlers in dense plasmas, highlighting multiple length scales and regimes.

Findings

Multiple wakefields can be excited due to Bohm potential effects.

Quantum tunneling enhances wakefield amplitude.

Strong magnetic fields reduce wakefield strength.

Abstract

The excitation of electrostatic wakefields in a magnetized spin quantum plasma by the classical as well as the spin-induced ponderomotive force (CPF and SPF, respectively) due to whistler waves is reported. The nonlinear dynamics of the whistlers and the wakefields is shown to be governed by a coupled set of nonlinear Schr\"{o}dinger (NLS) and driven Boussinesq-like equations. It is found that the quantum force associated with the Bohm potential introduces two characteristic length scales, which lead to the excitation of multiple wakefields in a strongly magnetized dense plasma (with a typical magnetic field strength $B_{0}\gtrsim10^{9}$ T and particle density $n_{0}\gtrsim10^{36}$ m$^{-3}$), where the SPF strongly dominates over the CPF. In other regimes, namely $B_{0}\lesssim10^{8}$ T and $\ n_{0}\lesssim10^{35}$ m$^{-3}$, where the SPF is comparable to the CPF, a plasma wakefield can also be excited self-consistently with one characteristic length scale. Numerical results reveal that the wakefield amplitude is enhanced by the quantum tunneling effect, however it is lowered by the external magnetic field. Under appropriate conditions, the wakefields can maintain high coherence over multiple plasma wavelengths and thereby accelerate electrons to extremely high energies. The results could be useful for particle acceleration at short scales, i.e. at nano- and micrometer scales, in magnetized dense plasmas where the driver is the whistler wave instead of a laser or a particle beam.