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 floating potential is gathered from two probes located 180 degrees 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 floating 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.

The non-uniform dc glow discharge plasma system is studied by using isolated computer controlled three couples of double probe system (TCDP) in argon gas, simultaneously. TCDP system has been developed to use for magnetized, unmagnetized, and for low oscillating plasma systems by using low pass filter with optically isolated circuitry to minimize the measurement errors with higher resolution and accuracy. Difference in the shapes and diameters of the discharge tube from region to region leads to change in the positive column glow discharge properties. This is because the positive column inhomogeneities, rising from the increase in the electron densities at the small tube radius region than the large one. Therefore, the axial electric field and the electron temperature have been diverted from their normal behavior in the positive column. However, at the large radius regions, the axial electric field seams to stay approximately constant at higher discharge currents. On the other hand, In this work the radial dependence of the electron temperature, density, floating potential, and the normalized probe radius (&amp / #958 / =rp&amp / #955 / D) has been investigated. Since, the probe radius is smaller than Debye length, the orbital motion limited (OML) theory has been used. As a result, the electron temperature (at the center) decreased and density increased with decreasing tube radius, and they have maximum values at the first probe (near the cathode). The electron density ne was observed to decrease and electron temperature Te to increase with increasing the discharge current. The floating potential has less negative value with decreasing tube radius except at the higher currents. Finally, it has been found that the &amp / #958 / is proportional with electron density, but it remains constant depending on the value of Te and ne.

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