Wave excitation by energetic ring-distributed electron beams in the solar corona

Abstract

We analyzed properties of waves excited by mildly relativistic electron beams propagating along magnetic field with a ring-shape perpendicular momentum distribution in neutral and current-free solar coronal plasmas. These plasmas are subject to both the beam and the electron cyclotron maser (ECM) instabilities driven by the positive momentum gradient of the ring-beam electron distribution in the directions parallel and perpendicular to the ambient magnetic field, respectively. To explore the related kinetic processes self-consistently, 2.5-dimensional fully kinetic particle-in-cell (PIC) simulations were carried out. To quantify excited wave properties in different coronal conditions, we investigated the dependence of their energy and polarization on the ring-beam electron density and magnetic field. In general, electrostatic waves dominate the energetics of waves and nonlinear waves are ubiquitous. In weakly magnetized plasmas, where the electron cyclotron frequency ${\omega }_{ce}$ is lower than the electron plasma frequency ${\omega }_{pe}$, it is difficult to produce escaping electromagnetic waves with frequency $\omega >{\omega }_{pe}$ and small refractive index $|ck/\omega |<1$ ($k$ and $c$ are the wavenumber and the light speed, respectively). Highly polarized and anisotropic escaping electromagnetic waves can, however, be effectively excited in strongly magnetized plasmas with ${\omega }_{ce}/{\omega }_{pe}\ge 1$. The anisotropy of the energy, circular polarization degree (CPD), and spectrogram of these escaping electromagnetic waves strongly depend on the number density ratio of the ring-beam electrons to the background electrons. In particular, their CPDs can vary from left-handed to right-handed with the decrease of the ring-beam density, which may explain some observed properties of solar radio bursts (e.g., radio spikes) from the solar corona.

arXiv commentApJ, accepted

References in corpus (24)

• Impulsive phase flare energy transport by large-scale Alfven waves and the electron acceleration problem
• A Review of Solar Type III Radio Bursts
• Stochastic Acceleration of Electrons and Protons. I. Acceleration by Parallel Propagating Waves
• Coherent Emission Mechanisms in Astrophysical Plasmas
• Particle Acceleration by a Solar Flare Termination Shock
• Emission of Type II Radio Bursts - Single-Beam versus Two-Beam Scenario
• Magnetic Reconnection Null Points as the Origin of Semi-relativistic Electron Beams in a Solar Jet
• Nonlinear Wave Interactions as Emission Process of Type II Radio Bursts
• Electron acceleration by cascading reconnection in the solar corona I Magnetic gradient and curvature effects
• Self-consistent particle-in-cell simulations of fundamental and harmonic plasma radio emission mechanisms
• Conditions for electron-cyclotron maser emission in the solar corona
• Energy loss of intergalactic pair beams: Particle-in-Cell simulation
• Kinetic turbulence in fast 3D collisionless guide-field magnetic reconnection
• Electron-cylotron maser radiation from electron holes: Upward current region
• Non-Maxwellian electron distribution functions due to self-generated turbulence in collisionless guide-field reconnection
• Electron-Cyclotron-Maser Observable Modes
• A new approach to the maser emission in the solar corona
• Is Cyclotron Maser Emission in Solar Flares Driven by a Horseshoe Distribution?
• Spectral evolution of two-dimensional kinetic plasma turbulence in the wavenumber-frequency domain
• Plasma Waves as a Benchmark Problem
• Two-stage electron acceleration by 3D collisionless guide field magnetic reconnection
• Electron cyclotron maser instability (ECMI) in strong magnetic guide field reconnection
• Particle Scattering off of Right-Handed Dispersive Waves
• Ring-shaped velocity distribution functions in energy-dispersed structures formed at the boundaries of a proton stream injected into a transverse magnetic field: Test-kinetic results

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• Plasma emission induced by ring-distributed energetic electrons in overdense plasmas
• Proton and Helium Heating by Cascading Turbulence in a Low-beta Plasma
• Nonthermal electron velocity distribution functions due to 3D kinetic magnetic reconnection for solar coronal plasma conditions
• Emission Characteristics of Energetic Electrons with Crescent-shaped Velocity Distributions
• Single-Mode Wave Decay