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Conversion of Electrostatic Plasma Waves into Electromagnetic Waves: Numerical Calculation of the Dispersion Relation for All Wavelengths
Author(s) -
Oya Hiroshi
Publication year - 1971
Publication title -
radio science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.371
H-Index - 84
eISSN - 1944-799X
pISSN - 0048-6604
DOI - 10.1029/rs006i012p01131
Subject(s) - physics , electromagnetic radiation , dispersion relation , electromagnetic electron wave , wave propagation , wavelength , plasma , landau damping , plasma oscillation , longitudinal wave , ion acoustic wave , mechanical wave , resonance (particle physics) , rectilinear propagation , computational physics , atomic physics , optics , quantum mechanics
The dispersion curves have been computed for a wide range of wavelengths from electromagnetic waves to electrostatic waves in a magnetoactive warm plasma with a Maxwellian velocity distribution function. The computation was carried out mainly for the perpendicular propagation mode. The upper hybrid resonance is the connection point of the electrostatic waves and the electromagnetic waves. The electrostatic waves not associated with the upper hybrid resonance are subjected to electron cyclotron damping when the wavelength becomes long. Oblique propagation is allowed for the electrostatic waves in a frequency range from the plasma frequency to the upper hybrid resonance frequency in the long‐wavelength region where Landau damping can be neglected and where the electrostatic mode smoothly connects to the electromagnetic X ‐mode. In a slightly inhomogeneous plasma, the Bernstein‐mode electrostatic wave can escape by being converted into the O ‐mode electromagnetic wave; two reflections take place during this escape process. The frequency range of the escape coincides with the Cerenkov radiation of the electromagnetic waves, but these two mechanisms indicate clear contrast in its origin. The electromagnetic Cerenkov radiation is produced interacting with the high‐energy plasma beam with velocity range l00υ th < υ < l000υ th (for the nonrelativisitic plasma), where υ th is the electron thermal velocity, whereas the origin of the electrostatic waves is in the interaction with the low‐energy plasma beam.