| The ionosphere is a conducting layer in the Earth's upper atmosphere and is the nearest naturally occurring plasma environment. Inherent to all plasma environments is an electric field. Currently, the double electric field probe is the most successful instrument for measuring the electric fields of space plasmas. Utah State University/Space Dynamics Lab has developed a double electric field probe, called the Floating Potential Probe (FPP), with a slightly different instrumentation approach than what has been done previously. The FPP is one component of a suite of instruments that launched in fall of 2007 from Wallops Island, Virginia, as part of NASA's sounding rocket program to an approximate altitude of 450km. This mission is nicknamed "The Storms Mission."In general, an electric field probe acts as a voltmeter to measure the electric potential between a probe located near the end of a long boom and the skin of the rocket. This measurement is also called the floating potential. To obtain electric field measurements, the oating potential is gathered from two probes located 180° apart and differenced to calculate the electric potential between probes and thereby the ambient electric field. Historically, this has been accomplished with an entirely analog circuit implementation. For the Storm Mission, the signals are digitized before the differencing occurs. Then during data analysis, the signals can either be differenced digitally to produce the ambient electric field or summed to observe the oating potential of the payload skin. Additionally, the signals are digitized to 20 bits giving a far greater dynamic range than is typically achieved in similar direct current (DC) coupled instruments. This thesis discusses the theory, design, test, and calibration efforts of the FPP for the Storms Mission. |
