Physics
Scientific paper
Dec 2009
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2009agufmsm41b1718c&link_type=abstract
American Geophysical Union, Fall Meeting 2009, abstract #SM41B-1718
Physics
[2704] Magnetospheric Physics / Auroral Phenomena, [2790] Magnetospheric Physics / Substorms
Scientific paper
In order to facilitate Poker Flat AMISR (PFISR) detection of plasma perturbations attributable to the ionospheric feedback instability (IFI), an ionosphere-centric derivation of the growth rate of the IFI has been carried out that accounts for the non-zero vertical thickness of the ionosphere, and the associated parallel electric field. The magnetosphere is treated as a complex admittance, which is determined by analysis of a long cascade of transmission line sections, terminated above the top boundary of the ionospheric Alfven resonator (IAR) by a matched load. The effect of ionospheric thickness is a significant reduction in the growth rate, especially at frequencies above the fundamental, and for “background” electric fields below about 50 mV/m. These dependencies are explained by the fact that the horizontal wavelength of the unstable mode is reduced as the mode frequency is increased, and as the background electric field is decreased. The effects are enough to require consideration in previous numerical simulations of the IFI, which do not include them. Of importance to the problem of detection, the unstable horizontal wavelength is less than 4 km for electric fields below 50 mV/m. Because the PFISR beam width is two to three kilometers (at 120 km in altitude), this means that the electric field needs be greater than 50 mV/m for PFISR to be able to detect density perturbations associated with the IFI. Since the plasma density tends to be low where/when the electric field is large, appropriate conditions are fairly rare. This may explain why our efforts to detect the IFI have so far not met with success. Growth rate versus frequency for the ionospheric feedback instability, for thin and finite thickness ionosphere.
Cosgrove Russell B.
Doe Richard
No associations
LandOfFree
Effects of Ionospheric Thickness on the Ionospheric Feedback Instability, and the Problem of Radar Detection does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Effects of Ionospheric Thickness on the Ionospheric Feedback Instability, and the Problem of Radar Detection, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Effects of Ionospheric Thickness on the Ionospheric Feedback Instability, and the Problem of Radar Detection will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1880109