# Containing intense laser light in circular cavity with magnetic trap door

## TL;DR

This study demonstrates via particle-in-cell simulation that intense circularly polarized laser light can be effectively contained within a magnetized circular plasma cavity, enabling prolonged interaction before dissipation.

## Contribution

It introduces a novel method of trapping intense laser light in a circular plasma cavity using magnetic fields, extending the duration of laser-plasma interaction.

## Key findings

- Laser light can be contained for hundreds of light-wave periods.
- The trapped laser undergoes multiple reflections with minimal energy loss.
- Frequency broadening and harmonic generation are weak and nearly isotropic.

## Abstract

It is shown by particle-in-cell simulation that intense circularly polarized (CP) laser light can be contained in the cavity of a solid-density circular Al-plasma shell for hundreds of light-wave periods before it is dissipated by laser-plasma interaction. A right-hand CP laser pulse can propagate almost without reflection into the cavity through a highly magnetized overdense H-plasma slab filling the entrance hole. The entrapped laser light is then multiply reflected at the inner surfaces of the slab and shell plasmas, gradually losing energy to the latter. Compared to that of the incident laser, the frequency is only slightly broadened and the wave vector slightly modified by appearance of weak nearly isotropic and homogeneous higher harmonics.