Excitation of extraordinary Bernstein waves by a beam of energetic electrons

Abstract

Abstract. This paper discusses an instability of extraordinary Bernstein waves, driven by a beam of energetic electrons. The present research is motivated by the study of solar radio emission processes, and its findings may have interesting implications. Specifically, the extraordinary Bernstein waves excited both below and above the plasma frequency by the present instability can, in principle, mode convert to either of the free-space propagating modes in the presence of magnetic field and/or density inhomogeneities. This paper is devoted to an analysis of the basic properties associated with the present instability over a wide range of various physical parameters.

Whistler Instability Driven by Electron Thermal Ring Distribution With Magnetospheric Application

“…Recently, we proposed that the ubiquitously observed fluctuations in the Langmuir/upper-hybrid frequency range, which is sometimes accompanied by (n + 1∕2)f ce , or multiple-harmonic electron cyclotron emissions, in the inner magnetosphere including the radiation belt environment (Christiansen et al, 1978a(Christiansen et al, , 1978bKurth et al, 1979aKurth et al, , 1979bMatsumoto & Usui, 1997;Usui et al, 1999;Kurth et al, 2015), can be interpreted in terms of the Bernstein mode instability or thermal emissions in the Bernstein modes (Lee et al, 2018a). Bernstein mode instability, or Harris instability, is associated with quasi-perpendicular electrostatic mode driven by weak loss cone feature associated with the magnetospheric electrons (Ashour-Abdalla & Kennel, 1978;Crawford, 1965;Crawford et al, 1967;Fleishman & Yastrebov, 1994;Fredericks, 1971;Harris, 1959;Hubbard & Birmingham, 1978;Karpman et al, 1975;Yoon & Wu, 1999;Young et al, 1973;Zheleznyakov & Zlotnik, 1975). Thermal emission is spontaneously emitted electrostatic fluctuations with enhanced intensities in the close vicinity of Bernstein modes (Hwang et al, 2017;Issautier et al, 2001;Meyer-Vernet et al, 1993;Moncuquet et al, 2005;Sentman, 1982;Yoon et al, 2017).…”

Simulation and Quasi‐linear Theory of Magnetospheric Bernstein Mode Instability

“…The multiple-harmonic electron cyclotron emissions are actually quite common in a variety of laboratory and space/astrophysical settings. In fact, early laboratory experiments as well as solar radio emissions in addition to magnetospheric examples have been interpreted in the light of electron Bernstein gryoharmonic instability theory (Ashour-Abdalla & Kennel, 1978;Crawford, 1965;Crawford et al, 1967;Fleishman & Yastrebov, 1994;Fredericks, 1971;Hubbard & Birmingham, 1978;Karpman et al, 1975;Yoon & Wu, 1999;Young et al, 1973;Zheleznyakov & Zlotnik, 1975).…”

Excitation of Bernstein waves by energetic pickup ions

“…In both areas, contemporary plasma physics plays fundamentally important roles. In several recent articles, the excitation of Bernstein waves in the solar corona (Yoon et al 1999;Ziebell et al 2000) and the energization of newly created ions near a flare site (Wang et al 2001) are discussed. In the former case, it is postulated that the excitation is mainly due to fast electrons streaming along the ambient magnetic field, and in the latter study the acceleration of ions is attributed to a pickup process by enhanced Alfvén waves in a reconnection layer.…”

“…Because Bernstein waves are propagating in directions perpendicular to an ambient magnetic field, usually these waves cannot be excited by particles that are moving along the background magnetic field. The works by Yoon et al (1999) and Ziebell et al (2000) make the point that a maser instability associated with a beam of fast electrons can occur. The theoretical analyses emphasize a resonant process that involves a relativistic effect.…”