Density measurements above and within a sporadic-E layer using Impedance Probes and Langmuir Probes

A Black Brant sounding rocket (NASA 21.125) was launched on June 29th, 2001 at 04:44~UTC (00:44~EST) from Wallops Flight Facility (WFF), Virginia, to study the relation of sporadic-E layers and quasi-periodic (Q-P) radar echoes and their electrodynamical properties. The launch was accompanied by VHF radar measurements from Fort Macon, NC, provided by the University of Illinois and ionosonde measurements at WFF. The rocket consisted of a main- and a sub-payload, each equipped with E-field sensors, a fixed-bias Langmuir probe in ion saturation mode, and a magnetometer. The main payload employed an additional Langmuir probe in electron saturation mode, a mutual impedance probe, and an ionization gauge. The rocket was launched during the presence of strong Q-P echos and a well-developed sporadic-E layer as measured by radar and ionosonde. Good data has been received from all instruments. The apogee of 122 km was reached after 179 seconds flight-time. Enhanced electron densities were encountered during the upleg and during the downleg at altitudes between 102 km and 107 km. At the same altitudes indications of resonances are visible in the impedance probe data. The Langmuir probes also revealed plasma density structures including quasi-periodic oscillations with ~0.8 sec periodicity, corresponding to ~400 m for horizontal structures aligned with the rocket velocity. These structures appear both above and within the sporadic-E layer and do not appear to be gradient-drift driven. In this paper, we concentrate on the density measurements gathered by the different techniques and use them to advance our current understanding of sporadic-E layer formation and structure.