The Formation by Electric Fields of Field‐Aligned Irregularities in the Magnetosphere

A possible mechanism for the formation of electron density irregularities in the magnetosphere is examined quantitatively. The mechanism involves localized E × B convection cells in which tubes of ionization with different total content are mixed. Under reasonable initial conditions, it is shown that a 0.1‐mv/m electric field in the equatorial plane can produce electron density enhancements and depressions of the order of 5% at L = 4 in about one‐half hour. These enhancements are large enough to trap whistler waves, whereas the depressions can trap HF waves. It is also shown that small‐scale density irregularities can be produced by a much larger scale electric field. It is suggested that thundercloud electricity may be a possible source of the electric field responsible for the irregularities.