The controllable super-high energetic electrons by external magnetic fields at relativistic laser-solid interactions in the presence of large scale pre-plasmas

TL;DR

This paper demonstrates that external magnetic fields can significantly enhance electron energies in relativistic laser-solid interactions with pre-plasmas, revealing a controllable mechanism for generating super-high energetic electrons up to 500 MeV.

Contribution

The study extends the two-stage electron acceleration model to include magnetic field effects, showing controllable electron energies and identifying a laser front sharpening mechanism at relativistic intensities.

Findings

Electron kinetic energy can reach 500 MeV with magnetic fields >10,000 T.

Magnetic fields enable control over electron energy cut-offs.

A laser front sharpening mechanism is identified at high magnetic fields.

Abstract

The two stage electron acceleration model [arXiv: 1512.02411 and arXiv: 1512.07546] is extended to the study of laser magnetized-plasmas interactions at relativistic intensities and in the presence of large-scale preformed plasmas. It is shown that the cut-off electron kinetic energy is controllable by the external magnetic field strength and directions. Further studies indicate that for a right-hand circularly polarized laser (RH-CP) of intensity $10^{20}\ \text{W}/\text{cm}^2$ and pre-plasma scale length $10\ \mu\text{m}$, the cut-off electron kinetic energy can be as high as $500\ \text{MeV}$, when a homogeneous external magnetic field of exceeding $10000\ \text{T}$ (or $B=\omega_{c}/\omega_0>1$) is loaded along the laser propagation direction, which is a significant increase compared with that $120\ \text{MeV}$ without external magnetic field. A laser front sharpening mechanism is identified at relativistic laser magnetized-plasmas interactions with $B=\omega_{c}/\omega_0>1$, which is responsible for these super-high energetic electrons.