Open AccessDispersive ionospheric Alfvén resonator
Author(s) -
Pokhotelov Oleg A.,
Pokhotelov D.,
Streltsov A.,
Khruschev V.,
Parrot M.
Publication year - 2000
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 - 10.1029/1999ja900480
Subject(s) - physics , ionosphere , dispersion relation , whistler , instability , geophysics , dispersion (optics) , computational physics , ionospheric heater , plasma , mechanics , optics , quantum mechanics
A new model of the ionospheric Alfvén resonator (IAR) including the effect of wave frequency dispersion is presented. It is shown that the shear Alfvén waves in the IAR are coupled to the compressional mode through the boundary conditions at the ionosphere. This coupling results in the appearance of the Hall dispersion and subsequent shift of the IAR frequency spectrum. The excitation mechanism involving the IAR interaction with the magnetospheric convective flow is considered. It is shown that the Hall dispersion of the IAR eigenmode increases the growth rate of the feedback instability. However, for the observed values of ionospheric conductivity this effect is not very high. It is shown that the physical mechanism of the feedback instability is similar to the Čerenkov radiation in collisionless plasmas. The IAR eigenfrequencies and growth rates are evaluated for the case of exponential variation of the Alfvén velocity with altitude in the topside ionosphere.