General dispersion relation for nonpotential ion harmonic waves propagating in plasmas with arbitrary β

The dispersion relation for nonpotential ion harmonic waves propagating at any angle to the magnetic field in plasmas with arbitrary β is derived for ω/k/sub z/>>V/sub i/, where ω/k/sub z/ is the parallel phase velocity and V/sub i/ is the ion thermal speed. It is shown that these slow waves can propagate in plasmas when the electron plasma pressure to magnetic pressure ratio β/sub e/, is much less than 1 and only in the wavenumber range k> (Pi/sub e//c)(ω/Ω/sub e/costheta)/sup 1/2/, where Pi/sub e/ is the plasma frequency, Ω/sub e/ is the electron gyrofrequency, c is the velocity of light, and theta is the propagation angle. Finally, a comparison between the properties of these slow waves and those of the fast electromagnetic ones, is given