Chapter 7 - Electric Field Measurement Techniques

Abstract

Measurements of atmospheric electric phenomena have been conducted for over a hundred years, going back to the experiments of Benjamin Franklin. These experiments were carried out in a very weakly ionized medium. Advances during the past few decades have been carried out in a highly conducting material called a plasma. New methods were needed and developed in the 1960s, with the realization of electric phenomena’s importance in space. As we shall see, the field can be deduced by direct measurements using what is basically a voltmeter or by measuring the plasma motion in response to electrical forcing. The latter has been accomplished by using chemical tracers, whose motion can be registered by cameras, by radars on the ground that record the material’s Doppler shift, and by detecting the plasma motion relative to a satellite’s velocity.