Simultaneous observation of the electron acceleration and ion deceleration in the dayside high‐latitude auroral region

Abstract

SS‐520‐2 sounding rocket flew through the dayside high‐latitude auroral region in the vicinity of the cusp. One of the science instruments LEP‐ESA/ISA simultaneously observed electron acceleration and ion deceleration when inverted‐V type electron precipitations were observed. The correspondence between the electron acceleration energy and the ion deceleration energy clearly indicated the existence of the quasi‐static field‐aligned potential drop above the sounding rocket. Moreover, ion deceleration started 9.5 seconds later than electron acceleration. By considering a simple temporal model that field‐aligned potential drop gradually grew in 10 seconds at 4200 km altitude region, we have succeeded in explaining the observed characteristics of the electron acceleration and ion deceleration.