AN EXPERIMENTAL STUDY OF PLASMA DYNAMICS IN THE AURORAL IONOSPHERE

In March 1979, the third and fourth Porcupine sounding rockets were launched into auroral arcs from a launch site in northern Sweden. At the beginning of each flight two instrumented subpayloads, a xenon ion source, and a barium shaped charge were ejected from the main payload. This thesis covers measurements returned by the instrumented subpayloads of the electric fields, magnetic fields, plasma waves, and particle fluxes in the auroral arcs and during the operation of the xenon ion source.; During the fourth flight, the subpayloads flew through the northern edge of an intense auroral arc. Two abrupt decreases in the precipitating electron energy and number flux were observed, and the precipitation boundaries were correlated with 20 to 60 mV/m increases in the ionospheric electric field and 0.1 to 0.2 A/m upward field aligned currents. The divergence of the electric field was calculated using simultaneous measurements by the two subpayloads and showed the expected build up of polarization charge at the precipitation boundaries. The direction and magnitude of the field aligned currents accompanying the electric field increases indicated that the magnetosphere was the source of the electric field perturbations and that the ionosphere was acting as a resistive load. Downward field aligned currents were observed adjacent to the regions of electron precipitation and may have been carried by ionospheric electrons moving up the magnetic field lines. These upward moving electrons may have drifted into the precipitation boundary and could have supplied the current necessary to maintain the observed electric field gradient.; Measurements made by the subpayloads during the ion source operation provided details on the evolution of an ion beam outside the constraints of a laboratory vacuum system. The beam was expected to generate a polarization electric field which would have allowed the beam to travel across the magnetic field, but an enhanced electric field in the beam was observed for distances less than 200 meters from the ion source. Because the region of increased electric field in the beam was less than the beam ion gyroradius of 520 meters, the beam ions were essentially following their individual gyromotions. The absence of a polarization electric field was confirmed by the measurement of the currents in the beam which indicated that the beam ions were moving though a stationary background of electrons and the observation that the beam ions were extending across the magnetic field from the ion source for distances less than twice the beam ion gyroradius.