Electron concentration at L approximately 1.8 obtained from whistler measurements

Whistlers observed in the same two-minute recording as well as whistlers observed in the course of several hours were used to provide data on electron concentration in the equatorial plane at heights ranging from 3,000 to 6,000 km. The nose frequency and the group delay of the whistlers were measured with geomagnetic latitude obtained from the nose frequency and electron distribution along the whistler propagation path obtained from group delay. The main problem in determining electron concentration by means of whistlers is to solve an integral equation for the group delay. Two models - the gyrofrequency model and a model of a multicomponent plasma in hydrostatic equilibrium along the geomagnetic field line are used to evaluate the integral equation.