Plasma Wave Field Generation by the Tethered Satellite System

Abstract

A main objective of the Italo‐American tethered satellite project TSS 1 is the investigation of induced plasma waves in the Earth's ionosphere. Therefore many theoretical models have been developed. In this paper we extend the model of Estes (1988) by including evanescent wave modes and multi‐ion effects. We use a plasma composition dominated by oxygen ions with an admixture of 10% protons to characterize the ionospheric F layer. Thus the highest frequencies in our model are far beyond the proton gyrofrequency. Because of this modification, the first band of frequencies where propagating waves are generated (Barnett and Olbert, 1986) splits into two parts, and waves in the proton whistler regime also contribute. In addition to the MHD‐Alfvén wing, a second wing, here called the proton whistler wing, is generated. The evanescent wave modes contribute to the wave field up to 4–5 km in the direction of the background magnetic field. These waves depend strongly on the initial source current distribution of the system and may affect the streaming ionospheric plasma. The impedance of the system in the frequency band considered is changed as a result of the change in the Alfvén speed, but it does not exceed the value of 2 ohms.