Ion cyclotron instabilities in high-β plasmas

The complete dispersion equation (including all the electromagnetic terms) for flute like (k/sub ///=0) ion cyclotron instabilities in a high beta plasma is solved using both numerical and analytic methods. A new type of ion cyclotron instability is found which is caused by the coupling of an electrostatic ion cyclotron wave with an electromagnetic ion cyclotron wave. The effect of magnetic field inhomogeneity is found to reduce the growth rate of this instability but does not stabilise it.