Detection of geomagnetically aligned currents associated with an auroral arc

Abstract

A rocket-borne experiment consisting of a vector magnetometer system and energetic charged particle detectors was launched from Fort Churchill, Canada, over a stable IBC II auroral arc at 2000 LT on February 26, 1969. Vector magnetic field profiles and energetic particle flux profiles are presented which indicate the existence of geomagnetically aligned sheet currents associated with the visible auroral arc. In particular, evidence is shown that suggests that precipitated energetic electrons in the range 2 to 18 kev carry a significant fraction of the total upward field-aligned current, but that energetic particles in this range are apparently unimportant in providing the downward return current. The spatial relation of the precipitated particle structure and the auroral current configuration are discussed.