Langmuir waves from trapped superthermal electrons

Abstract

view Abstract Citations (12) References (30) Co-Reads Similar Papers Volume Content Graphics Metrics Export Citation NASA/ADS Langmuir waves from trapped superthermal electrons Wentzel, D. G. Abstract A 'gap' distribution of trapped superthermal but nonrelativistic electrons may generate Langmuir waves with a high brightness temperature 1/2 mc-squared, which has been invoked to explain the solar type I radio continuum. The conditions under which the Langmuir waves can actually become this intense when the electrons are treated as magnetized with a gyrofrequency smaller than the plasma frequency are evaluated. For isotropic electrons at a single velocity, there arise many instabilities, but most disappear for a slightly broadened velocity distribution. A serious Cerenkov instability, equivalent to the two-stream instability, occurs for electrons of small pitch angles. It is avoided by a modest loss cone. Then the Langmuir waves within 45 deg of the magnetic field can indeed achieve the expected high brightness temperature. The solar type I radio continuum can be explained in terms of a nonrelativistic electron gap distribution. Superthermal microwave gyroradiation implies sufficient superthermal electrons that their Langmuir waves might cause observable microwave emission at twice the plasma frequency. Publication: The Astrophysical Journal Pub Date: September 1985 DOI: 10.1086/163445 Bibcode: 1985ApJ...296..278W Keywords: Electrostatic Waves; Solar Corona; Solar Electrons; Solar Radio Emission; Cerenkov Radiation; Gyrofrequency; Harmonic Radiation; Microwave Emission; Solar Physics full text sources ADS |