Abnormal Depression of a Rocket's Potential Accompanied by Low-Frequency Fluctuations of the Electron Density and Electric Field in the E-Region

A sounding rocket was launched in January 1988 to locate heat sources which may cause the anomalous elevation of the E-region electron temperature over Kagoshima, Japan. Fluctuations of the electron density and the electric field were measured using a fixed-biased Langmuir probe (PWN) and a pair of double probes (AEF) respectively, placed onboard the rocket. The PWN measured an abrupt decrease in DC current and an increase in AC current (5-160Hz component) at the altitude of 94-130km along the rocket's ascending path. The AEF also measured an increase in AC electric field (5-160Hz component) in the same altitude. Comparative analysis of the PWN and AEF data reveals that the potential of the rocket dropped a few volts accompanied by low-frequency fluctuations in that altitude range. An other research group of the same rocket measured an elevated electron temperature in the same altitude range. Coincident occurrence of these phenomena suggests common cause. The suprathermal electrons are considered to be a promising candidate.