Surface-Wave Instability in Helicon-Wave Propagation

A novel instability is described which can be utilized to amplify helicon waves in a single-component solid-state plasma. The instability is created by carrier drift at threshold velocities which can be smaller than the phase velocity of the wave which is being amplified. The instability can be excited in composite structures made up of two or more layers of solid-state plasma of different carrier densities with the interface parallel to an applied static magnetic field. It is intrinsically connected with the presence of a surface wave at the interface between the two media.