High-speed ion flow, substorm current wedge, and multiple Pi2 pulsations

We have studied the onset timing of Earthward high-speed ion flow observed by the AMPTE/IRM satellite at 12.3 Earth Radii (R_E) and 01 magnetic local time (MLT) in the central plasma sheet during an isolated substorm event on March 1, 1985. The timing of this onset is compared with that of the substorm current wedge and Pi2 magnetic pulsations observed by a large number of ground-based stations and the AMPTE/CCE, GOES 5, ISEE 1, and SCATHA satellites and with that of particle injection observed at Los Alamos geosynchronous satellite 1982-019. On the basis of these observations, we conclude that the substorm current wedge is formed due to plasma processes at the braking point of the Earthward high-speed flow during the initial stage of the substorm expansion phase. The braking point is well-separated from the near-Earth neutral line. It is also suggested that the compressional pulses and the field-aligned currents generated at the braking point of the flow can be the initial cause of the Pi2 magnetic pulsations in the inner magnetosphere. (orig.)50 refs.SIGLEAvailable from TIB Hannover: RN 9303(394) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman