Measurement of Maxwell Currents Using an Atmospheric Electrometer
Document ID: 342
Senior Honors Thesis
1 The Pennsylvania State University Department of Electrical and Computer Engineering, University Park, PA, U.S.A.
Introduction
The Geophysics Data Center (GDC) in the Department of Electrical and Computer Engineering at The Pennsylvania State University is concerned with the collecting, storing and displaying of various information pertaining to the Earth's geophysical environment. The GDC has several instruments currently (spring 1992) built with more expected. This instrument, an atmospheric electrometer, is one of the instruments to be incorporated into the GDC.
The Electrometer measures the current in the atmosphere on a continuous basis. Current in the atmosphere is primarily caused by thunderstorms which can be thought of as the power supplies in the global circuit. The amount of current measured, however, is heavily influenced by atmospheric conditions, namely wind.
As a consequence of measuring atmospheric current, Earth's electric field strength can be inferred by calculation. However, an accurate reading of the electric field using an electrometer can only be made when stable atmospheric conditions are present. In order to reduce the effect of the environment, an electric field-mill should be employed to give an accurate readings of the electric field. The electric field-mill alternately exposes and conceals a metal plate to the atmosphere and measures the change of charge in a known time interval. For more information, see reference 6.
Another motivation for building an electrometer is cost. Commercially available electrometers sell for over $2000. The electrometer built in this paper costs about $400. The commercial electrometer does, of course have other options available.
| Citation: | E. J. Novitsky, "Measurement of Maxwell Currents Using an Atmospheric Electrometer", The Pennsylvania State University, Senior Honors Thesis, 1992, 25 pages |