Instability of the cometary plasma tail - the instability in a plasma sheet

We consider the instability of the cometary plasma tail which is composed of a neutral sheet, two lobes of the ion tail and solar wind. The plasma is assumed to be highly conductive and incompressible. The unstable state yields a magnetic field which is perpendicular to the tail axis. Our result is consistent with findings about plasma from the International Cometary Explorer (ICE).