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Two‐dimensional numerical simulation of O ‐mode to Z ‐mode conversion in the ionosphere
Author(s) -
Can P. D.,
Honary F.,
Borisov N.
Publication year - 2016
Publication title -
journal of geophysical research: space physics
Language(s) - English
Resource type - Journals
eISSN - 2169-9402
pISSN - 2169-9380
DOI - 10.1002/2015ja022105
Subject(s) - physics , ionosphere , plasma , finite difference time domain method , computational physics , zenith , optics , electron density , electric field , perturbation (astronomy) , atomic physics , geophysics , quantum mechanics
Experiments in the illumination of the F region of the ionosphere via radio frequency waves polarized in the ordinary mode ( O ‐mode) have revealed that the magnitude of artificial heating‐induced effects depends strongly on the inclination angle of the pump beam, with a greater modification to the plasma observed when the heating beam is directed close to or along the magnetic zenith direction. Numerical simulations performed using a recently developed finite‐difference time‐domain (FDTD) code are used to investigate the contribution of the O ‐mode to Z ‐mode conversion process to this effect. The aspect angle dependence and angular size of the radio window for which conversion of an O ‐mode pump wave to the Z ‐mode occurs is simulated for a variety of plasma density profiles including 2‐D linear gradients representative of large‐scale plasma depletions, density‐depleted plasma ducts, and periodic field‐aligned irregularities. The angular shape of the conversion window is found to be strongly influenced by the background plasma profile. If the Z ‐mode wave is reflected, it can propagate back toward the O ‐mode reflection region leading to resonant enhancement of the electric field in this region. Simulation results presented in this paper demonstrate that this process can make a significant contribution to the magnitude of electron density depletion and temperature enhancement around the resonance height and contributes to a strong dependence of the magnitude of plasma perturbation with the direction of the pump wave.