Open AccessThe 2 f p radiation from localized Langmuir waves
Author(s) -
Malaspina David M.,
Cairns Iver H.,
Ergun Robert E.
Publication year - 2010
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.67
H-Index - 298
eISSN - 2156-2202
pISSN - 0148-0227
DOI - 10.1029/2009ja014609
Subject(s) - physics , plasma oscillation , plasma , radiation , computational physics , atomic physics , langmuir turbulence , antenna (radio) , electron , electromagnetic radiation , optics , telecommunications , quantum mechanics , computer science
A formalism is developed in which Langmuir waves, localized as eigenmodes of solar wind density cavities, emit coherent electromagnetic radiation as antennas at twice the local plasma frequency. Theoretical estimates are presented for the total power emitted as antenna radiation from localized Langmuir currents. The dependence of emitted power on wave packet properties and plasma environmental parameters is explored. STEREO observations demonstrate that the currents required for eigenmode antenna radiation are present and have strengths within an order of magnitude of theoretical predictions. The intensity of radio emission from the Earth's foreshock at twice the local electron plasma frequency is estimated based on measured distributions of electric field strength and wave packet localization scale. The eigenmode antenna radiation mechanism implies that, out of the total number of Langmuir waves excited by an electron beam, relatively few localized antenna radiators may account for a majority of observed emission from an extended radio source.