Experimental study of double resonance parametric excitations in the ionosphere

Abstract

We report the double resonance excitation of two pump waves with frequencies separated from 5 to several hundred Hz. The cyclotron frequencies of NO+ and O2+, abundant at the bottom of the F layer (∼ 150 km), are within this range. The nonlinear mode coupling takes place at ∼ 150 km where the pump frequency matches the plasma frequency. The experiments show that when the beat frequency is close to the NO+ cyclotron frequency at ∼ 30 Hz, the energy transfer from the higher frequency to the lower frequency wave is enhanced through parametric coupling. When the two pump waves have equal power, discrete sidebands are symmetrically distributed around the pump frequencies. However, a burst of lower‐frequency sidebands, lasting for several seconds, frequently breaks the symmetry. We attribute this asymmetry to the cascade parametric process. The asymmetric spectra only occur only during O mode experiments.

Comparison of ELF/VLF generation modes in the ionosphere by the HIPAS heater array

“…In addition, sky wave HF signals were monitored at the Gilmore Creek site using a coaxial-collinear array circularly polarized in the right-hand direction. A Racal RA6790/GM receiver with a bandwidth of 8 kHz, centered at the heater frequency of 2.85 MHz, was then used to detect the signal [Song et al, 1995].…”

Numerical study on matching conditions of Langmuir parametric instability and the formation of Langmuir turbulence in ionospheric heating

“…Parametric instability in ionospheric heating by powerful highfrequency radio waves has been investigated both theoretically and experimentally for many years (Fejer, 1979;Stenflo, 1985;Leyser, 1991;Song B et al, 1995;Kuo SP, 2014;Akbari et al, 2017). Langmuir parametric instability, which is related to Langmuir wave excitation, is excited below the O-mode wave reflection point.…”