On instability of low-frequency waves in a stream-magnetized plasma system

The interaction of low-frequency electromagnetic waves propagating at an arbitrary angle to the static magnetic field with a nearly synchronous charged stream along the field in a cold plasma is analyzed. The temporal growth of the waves is found to increase with the signal frequency, the stream density, and the propagation angle off the field line. Explicit forms of maximum growth rate are derived for VLF and ELF waves, and a numerical example is given for a typical ionospheric plasma near the magnetic equator.