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.