3D particle-in-cell simulation of electron acceleration by Langmuir waves in an inhomogeneous plasma

Abstract

A possible solution to the unexplained high intensity hard x-ray (HXR) emission observable during solar flares was investigated via 3D fully relativistic, electromagnetic particle-in-cell (PIC) simulations with realistic ion to electron mass ratio. A beam of accelerated electrons was injected into a magnetised, Maxwellian, homogeneous and inhomogeneous background plasma. The electron distribution function was unstable to the beam-plasma instability and was shown to generate Langmuir waves, while relaxing to plateau formation. In order to estimate the role of the background density gradient on an unbound (infinite spatial extent) beam, three different scenarios were investigated: a) a uniform density background; b) a weak density gradient, n_R/n_L=3; c) a strong gradient case, n_R/n_L=10, where n_R and n_L denote background electron densities on the left and right edges of the simulation box respectively. The strong gradient case produced the largest fraction of electrons beyond 15 v_th. Further, two cases (uniform and strong gradient background) with spatially localized beam injections were performed aiming to show drifts of the generated Langmuir wave wavenumbers, as suggested in previous studies. For the strong gradient case, the Langmuir wave power is shown to drift to smaller wavenumbers, as found in previous quasi-linear simulations.

References in corpus (3)

• Impulsive phase flare energy transport by large-scale Alfven waves and the electron acceleration problem
• Radio Spectral Evolution of an X-ray Poor Impulsive Solar Flare: Implications for Plasma Heating and Electron Acceleration
• Determining the wavelength of Langmuir wave packets at the Earth's bow shock

Cited by in corpus (8)

• A Unified Computational Model for Solar and Stellar Flares
• A comparison of weak-turbulence and PIC simulations of weak electron-beam plasma interaction
• Particle-in-cell simulations of the relaxation of electron beams in inhomogeneous solar wind plasmas
• Highly efficient electromagnetic emission during 100 keV electron beam relaxation in a thin magnetized plasma
• Bridging High-Density, Electron Beam Coronal Transport and Deep Chromospheric Heating in Stellar Flares
• Electron plasma wake field acceleration in solar coronal and chromospheric plasmas
• The effect of a longitudinal density gradient on electron plasma wake field acceleration
• Numerical simulations of a continuously injected relativistic electron beam relaxation into a plasma with large-scale density gradients