INTENSE ELECTROSTATIC-WAVES NEAR THE UPPER HYBRID-RESONANCE FREQUENCY

Plasma wave measurements using instruments on the Imp 6 and Hawkeye 1 satellites are utilized in a study of very intense electrostatic waves near the upper hybrid resonance frequency in the region just outside the plasmapause. These intense plasma wave events have electric field strengths of similar 1 - 20 mV m** minus **1 and are among the most intense waves seen in the earth's magnetosphere. Detailed studies of more than 140 of these intense electrostatic disturbances reveal that the events occur at all local times and at magnetic latitudes varying from the equator to as high as 50 degree . The characteristics of these waves are discussed. A possible mechanism for producing intense waves near the upper hybrid resonance frequency is suggested. Evidence suggests that the intense electrostatic waves may be a source of nonthermal continuum radiation.