Deciphering in situ electron dynamics of ultrarelativistic plasma via polarization pattern of emitted gamma photons

TL;DR

This paper introduces a novel method using gamma-photon polarization patterns to in situ probe ultrarelativistic plasma dynamics, revealing electron behavior and quantum electrodynamical effects during laser-plasma interactions.

Contribution

The study presents a new polarization-based technique for in situ analysis of plasma dynamics and quantum effects in ultrarelativistic regimes, advancing plasma diagnostics.

Findings

Polarization patterns correlate with electron dynamics.

Gamma-photon circular polarization indicates quantum electrodynamical processes.

Method provides detailed insights into laser-plasma interactions.

Abstract

Understanding and interpretation of the dynamics of ultrarelativistic plasma is a challenge, which calls for the development of methods for \textit{in situ} probing the plasma dynamical characteristics. We put forward a new method, harnessing polarization properties of $\gamma$-photons emitted from a non-pre-polarized plasma irradiated by a circularly polarized pulse. We show that the angular pattern of $\gamma$-photon linear polarization is explicitly correlated with the dynamics of the radiating electrons, which provides information on the laser-plasma interaction regime. Furthermore, with the $\gamma$-photon circular polarization originating from the electron radiative spin-flips, the plasma susceptibility to quantum electrodynamical processes is gauged. Our study demonstrates that the polarization signal of emitted $\gamma$-photons can be a versatile information source, which would be beneficial for the research fields of laser-driven plasma, accelerator science, and laboratory astrophysics.