Ion acoustic wave forms generated by ion-ion streams at the Earth's bow shock

The electric field experiment on board ISEE-1 had a special mode of operation in which bursts of very high time resolution measurements were stored and slowly read-out. This mode of operation allows us to study in detail the waveforms of the large amplitude electrostatic waves observed at the Earth's bow shock in a frequency range (10--500 Hz) not well covered previously. These waves appear to be correlated with two streams in the ion angular distribution. Our observations indicate, therefore, that the ion--ion stream instability is the dissipation mechanism of a collisionless fast quasi-perpendicular shock wave.