Electric Field Driven Instabilities in the Auroral Zone Ionosphere
Location
Yosemite National Park
Start Date
2-8-1974 10:45 AM
End Date
2-8-1974 11:00 AM
Description
Due co their low phase velocity, electrostatic waves interact more strongly with a low beta plasma than do electromagnetic waves. Recently, measurements of the electric field and plasma density fluctuations associated with such waves have been made on rockets and satellites. Simultaneous measurements of the convection electric field have been made on the same vehicles and several mechanisms for ionospheric plasma instability have been identified. 1) The electric field and plasma density oscillations associated with two stream instability of the auroral electrojet have been detected and shown to agree very well with theoretical predictions for the phase velocity, spectrum, direction of k, wave amplitude and relation to the driving electric field. These E region waves did not couple to the F region. 2) Strong F region electric field fluctuations were observed during another experiment on magnetic field lines in contact with a region in which the electric field was parallel to a plasma density gradient pointing toward an auroral arc. The condition EHV n is unstable only in the E Region. Thus, the F region observations indicate that the instability couples to the F region where a secondary effect such as the drift wave instability may operate.
Electric Field Driven Instabilities in the Auroral Zone Ionosphere
Yosemite National Park
Due co their low phase velocity, electrostatic waves interact more strongly with a low beta plasma than do electromagnetic waves. Recently, measurements of the electric field and plasma density fluctuations associated with such waves have been made on rockets and satellites. Simultaneous measurements of the convection electric field have been made on the same vehicles and several mechanisms for ionospheric plasma instability have been identified. 1) The electric field and plasma density oscillations associated with two stream instability of the auroral electrojet have been detected and shown to agree very well with theoretical predictions for the phase velocity, spectrum, direction of k, wave amplitude and relation to the driving electric field. These E region waves did not couple to the F region. 2) Strong F region electric field fluctuations were observed during another experiment on magnetic field lines in contact with a region in which the electric field was parallel to a plasma density gradient pointing toward an auroral arc. The condition EHV n is unstable only in the E Region. Thus, the F region observations indicate that the instability couples to the F region where a secondary effect such as the drift wave instability may operate.