Abstract
Abstract. An ordinary mode electromagnetic wave can decay into an ion acoustic wave and a scattered electromagnetic wave by a process called stimulated Brillouin scatter (SBS). The first detection of this process during ionospheric modification with high power radio waves was reported by Norin et al. (2009) using the HAARP transmitter in Alaska. Subsequent experiments have provided additional verification of this process and quantitative interpretation of the scattered wave frequency offsets to yield measurements of the electron temperatures in the heated ionosphere. Using the SBS technique, electron temperatures between 3000 and 4000 K were measured over the HAARP facility. The matching conditions for decay of the high frequency pump wave show that in addition to the production of an ion-acoustic wave, an electrostatic ion cyclotron wave may also be produced by the generalized SBS processes. Based on the matching condition theory, the first profiles of the scattered wave amplitude are produced using the stimulated Brillouin scatter (SBS) matching conditions. These profiles are consistent with maximum ionospheric interactions at the upper-hybrid resonance height and at a region just below the plasma resonance altitude where the pump wave electric fields reach their maximum values.
Highlights
Many types of waves exist in the ionospheric F-region plasma that is primarily composed of electrons and O+ ions in the earth’s magnetic field
The waves supported in this plasma include O-mode and X-mode electromagnetic waves, electron plasma waves, ion acoustic waves, upper hybrid waves, lower hybrid waves, electron and ion Bernstein waves, electron whistler waves, and ion cyclotron waves
This paper has provided experimental measurements of stimulated Brillouin scatter supported by wave matching theory and ray tracing
Summary
Many types of waves exist in the ionospheric F-region plasma that is primarily composed of electrons and O+ ions in the earth’s magnetic field. In a recent paper, Norin et al (2009) have produced the first detection in the ionosphere of an electromagnetic pump from the ground exciting the stimulated Brillouin scatter (SBS) instability using transmissions from the HAARP facility in Alaska. They recorded the stimulated electromagnetic emissions (SEE) in a 100 Hz band near the pump frequency. The wave number and wave frequency matching conditions are solved with the dispersion equations for the ion acoustic and electromagnetic waves keeping all of the effects of the ion and electron gyro frequencies These solutions provide an analytic expression that will yield measurements of the electron temperatures in the upper hybrid interaction regions based on the frequencies of the widely spaced SBS lines. The stimulated Brillouin spectra interpretation provides a powerful remote sensing tool for the modified ionospheric environment
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
