Alfven wave generation by means of high orbital injection of barium cloud in magnetosphere

Abstract

An analysis of the Alfven wave generation associated with the barium vapor release at altitudes ∼ 5.2 R E in the magnetosphere is presented. Such injections were executed in G-8 and G-10 experiments of the Combined Radiation and Radiation Effects Satellite (CRRES) mission. It is shown that the generation of Alfven waves is possible throughout the whole time of the expansion of plasma cloud. The maximum intensity of these waves corresponds to the time of complete retardation of the diamagnetic cavity created by the expansion of the plasma cloud. The Alfven wave exhibits a form of an impulse with an effective frequency ∼ 0.03–0.05 Hz. Due to the background conditions and wave frequency, the wave mainly oscillates along the geomagnetic field between the mirror reflection points situated at ∼ 0.7 R E i.e. the wave is trapped by the magnetospheric Alfven resonator. The reflection coefficient is about 80–85%. The wave amplitude is sufficient to the generation of plasma instabilities and longitudinal electric fields, and to an increase in the longitudinal energy of electrons accelerated by this field up to ∼ 1 keV. These processes are the most probable for altitudes ∼ 1 R E . The auroral kilometric radiation (AKR) at frequencies ∼ 100 kHz is associated with these accelerated electrons. It is shown that the acceleration of electrons and AKR can be observed almost continuously during the first minute and then from time to time with pauses about 35–40 s till 6–8 min after the release. Apparently, these findings do not contradict the experimental data. The betatron acceleration of electrons at the recovery of the geomagnetic field is also discussed. This mechanism could be responsible for the acceleration of electrons resulting in the aurorae and ultra short radio wave storm at frequencies 50–300 MHz observed at the 8–10th min after the release.