Ion wave instability in an electrostatic shock

An interesting feature of the collisionless electrostatic shock in a plasma is the reflection of ions by the shock front. Recently, in an experiment, Taylor, Baker and Ikezi (1970) observed a collisionless electrostatic shock with a small precursor moving at speeds greater than the shock. They used an ion-energy analyser and found this precursor to be a group of streaming ions causing a double- humped ion distribution. The authors have investigated the instabilities arising in linear longitudinal waves by employing a double-humped-or the so-called bump in tail-ion velocity distribution.