Relativistic Topological Waves from Cherenkov and Doppler Resonances in Self-Magnetized Laser Plasmas

TL;DR

This paper demonstrates the generation of relativistic topological waves at plasma interfaces through Cherenkov and Doppler resonances, using theoretical analysis and 3D particle-in-cell simulations of laser-plasma interactions.

Contribution

It introduces the concept of relativistic topological waves generated via resonances in self-magnetized laser plasmas, revealing new slow-wave branches and persistent electron acceleration.

Findings

Relativistic topological waves are generated at plasma interfaces.

Cherenkov and Doppler resonances excite multiple frequency-shifted modes.

A remnant relativistic mode continues electron acceleration after laser passage.

Abstract

Strong magnetic fields at plasma-plasma interfaces can be naturally produced in laser-plasma interactions. Using theoretical analysis and fully three-dimensional particle-in-cell simulations, we demonstrate that relativistic topological waves can be generated via Cherenkov and Doppler resonances in the interaction of intense femtosecond laser pulses with near-critical-density plasmas. At the self-magnetized plasma-plasma interface, a new slow-wave branch appears. Its phase velocity is much smaller than the group velocity of the laser pulse and the electron beam velocity. Therefore, the Cherenkov resonance condition can be easily satisfied. Furthermore, since electrons undergo betatron oscillations, Doppler resonances may also occur and are responsible for the excitation of several frequency-shifted branches observed in our simulations. After the passage of the laser pulse, we observe a fast remnant mode with relativistic amplitude and frequency close to the local plasma frequency. This mode continues to accelerate electrons further for many tens of laser periods even after the laser pulse has left the plasma.