Premium
Excitation threshold and gyroharmonic suppression of artificial E region field‐aligned plasma density irregularities
Author(s) -
Hysell D. L.,
Nossa E.,
McCarrick M.
Publication year - 2010
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 - 10.1029/2010rs004360
Subject(s) - excitation , plasma , atomic physics , physics , field (mathematics) , computational physics , mathematics , nuclear physics , quantum mechanics , pure mathematics
Ionospheric modification experiments have been carried out using the HAARP facility along with a 30 MHz coherent scatter radar imager in Alaska to examine properties of artificial E region field‐aligned plasma density irregularities (FAIs). In one set of experiments, the RF emission power was varied gradually in order to determine the threshold electric field for irregularity generation. A threshold O mode peak electric field amplitude of 170–195 mV/m at an altitude of 99 km and a heating frequency of 2.7 MHz was identified based on the full‐wave formalism of Thidé and Lundborg (1986). In another, the pump frequency was varied gradually to investigate the suppression of the FAIs at frequencies near the second electron gyroharmonic frequency (2Ω e ). Coherent echoes were found to be suppressed for pump frequencies in an asymmetric band 40–50 kHz wide around 2Ω e but only for irregularities driven marginally above threshold. Theoretical context for these results is provided.