Density fluctuations and the acceleration of electrons by beam-generated Langmuir waves in the solar corona

Abstract

Non-thermal electron populations are observed throughout the heliosphere. The relaxation of an electron beam is known to produce Langmuir waves which, in turn, may substantially modify the electron distribution function. As the Langmuir waves are refracted by background density gradients and as the solar and heliospheric plasma density is naturally perturbed with various levels of inhomogeneity, the interaction of Langmuir waves with non-thermal electrons in inhomogeneous plasmas is an important topic. We investigate the role played by ambient density fluctuations on the beam-plasma relaxation, focusing on the effect of acceleration of beam electrons. The scattering of Langmuir waves off turbulent density fluctuations is modeled as a wavenumber diffusion process which is implemented in numerical simulations of the one-dimensional quasilinear kinetic equations describing the beam relaxation. The results show that a substantial number of beam electrons are accelerated when the diffusive time scale in wavenumber space τ_D is of the order of the quasilinear time scale τ_ql, while when τ_D << τ_ql, the beam relaxation is suppressed. Plasma inhomogeneities are therefore an important means of energy redistribution for waves and hence electrons, and so must be taken into account when interpreting, for example, hard X-ray or Type III emission from flare-accelerated electrons.

References in corpus (5)

• Nonlinear development of electron-beam-driven weak turbulence in an inhomogeneous plasma
• Dynamics of electron beams in the solar corona plasma with density fluctuations
• Wave-particle interactions in non-uniform plasma and the interpretation of Hard X-ray spectra in solar flares
• Electron acceleration during three-dimensional relaxation of an electron beam-return current plasma system in a magnetic field
• Vlasov-Maxwell, self-consistent electromagnetic wave emission simulations in the solar corona

Cited by in corpus (15)

• A Review of Solar Type III Radio Bursts
• Anisotropic Radio-Wave Scattering and the Interpretation of Solar Radio Emission Observations
• Large scale simulations of solar type III radio bursts: flux density, drift rate, duration and bandwidth
• Particle-in-cell and weak turbulence simulations of plasma emission
• The Low-High-Low Trend of Type III Radio Burst Starting Frequencies and Solar Flare Hard X-rays
• Langmuir Wave Electric Fields Induced by Electron Beams in the Heliosphere
• Spatial expansion and speeds of type III electron beam sources in the solar corona
• Harmonic radio emission in randomly inhomogeneous plasma
• Stopping Frequency of Type III Solar Radio Bursts in Expanding Magnetic Flux Tubes
• A Fokker-Planck Framework for Studying the Diffusion of Radio Burst Waves in the Solar Corona
• Plasma radio emission from inhomogeneous collisional plasma of a flaring loop
• Simulation of plasma emission in magnetized plasmas
• Resonance broadening due to particle scattering and mode-coupling in the quasi-linear relaxation of electron beams
• Effect of turbulent density-fluctuations on wave-particle interactions and solar flare X-ray spectra
• Bridging High-Density, Electron Beam Coronal Transport and Deep Chromospheric Heating in Stellar Flares