2024/07/18 by Ian E. Ochs, Ochs, Ian E. · 1 citation
Physics and Astronomy · #Dust and Plasma Wave Phenomena #FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE) #Laser-Plasma Interactions and Diagnostics #Magnetic confinement fusion research #Plasma Physics (physics.plasm-ph)
paper · pdf · doi:10.48550/arxiv.2407.13106
openalex publication_date 2024/07/18 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28
Recent work has shown that synchrotron emission from relativistic plasmas leads the electron distribution to form an anisotropic ring in momentum space, which can be unstable to both kinetic and hydrodynamic instabilities. Fundamental to these works was the assumption that the plasma was optically thin, allowing all emitted radiation to escape. Here, we examine the behavior of these instabilities as the plasma becomes more optically thick. To do this, we extend a recently-developed Fokker-Planck operator for synchrotron emission and absorption in mildly relativistic plasmas to fully relativistic plasmas. For a given set of plasma parameters, photons emitted by higher-energy electrons tend to be higher frequency, and thus more easily escape the plasma. As a result, the ratio of the photon emission rate (radiative drag) to absorption rate (radiative diffusion) for a given electron is extremely energy-dependent. Given this behavior, we determine the critical parameters that control the opacity, and show how the plasma gradually transitions to become more isotropic and stable at higher opacity.