Ion‐Pedersen drift and parallel electric field effects on plasma jetting

Abstract

The combination of ion‐Pedersen currents and parallel electric fields are shown to affect significantly both the jetting of ionospheric plasma clouds transverse to the geomagnetic field and the Alfven waves generated by the moving plasma. Ion‐Pedersen currents and parallel electric fields invalidate the “frozen‐in” field approximation and cause Alfven waves to decay. They also imply an eigenvalue condition on the size of the plasma cloud transverse to the geomagnetic field and the direction of cloud motion. The attenuation of Alfven waves reduces the likelihood that the waves can cause an electromagnetic pulse on the ground and implies that the initial directed energy in the plasma jet is coupled, over great distances, to ions and electrons. It is suggested that two phenomena are more likely to occur at higher altitudes (e.g., > 500 km), where neutral and ambient densities become smaller. First, there is the substantial displacement of plasma clouds with an accompanying temporary change in the geomagnetic field. Second, the Alfven waves created in response to the motion of plasma clouds are less subject to attenuation and more likely to cause an electromagnetic pulse on the ground.