# Laser Amplification in Strongly-Magnetized Plasma

## TL;DR

This paper explores laser pulse backscattering in strongly-magnetized plasma via kinetic magnetohydrodynamic waves, revealing a high-growth-rate instability with broad bandwidth suitable for ultrashort pulse amplification.

## Contribution

It introduces magnetized low-frequency scattering as a new, efficient laser amplification mechanism with higher growth rates and broader bandwidth than traditional methods.

## Key findings

- MLF scattering has higher growth rate than Raman scattering.
- Supports ultrashort pulse durations due to large bandwidth.
- Can become the dominant backscatter instability in certain conditions.

## Abstract

We consider backscattering of laser pulses in strongly-magnetized plasma mediated by kinetic magnetohydrodynamic waves. Magnetized low-frequency scattering, which can occur when the external magnetic field is neither perpendicular nor parallel to the laser propagation direction, provides an instability growth rate higher than Raman scattering and a frequency downshift comparable to Brillouin scattering. In addition to the high growth rate, which allows smaller plasmas, and the 0.1-2\% frequency downshift, which permits a wide range of pump sources, MLF scattering is an ideal candidate for amplification because the process supports an extremely large bandwidth, which particle-in-cell simulations show produces ultrashort durations. Under some conditions, MLF scattering also becomes the dominant spontaneous backscatter instability, with implications for magnetized laser-confinement experiments.