Strong decay modes of warm space-charge waves in thermal plasma waveguides

The strong collisional decay modes of warm space-charge waves are derived in a thermal plasma waveguide composed of warm collisional electrons and cold ions. The kinetic theory is applied to obtain the dispersion relation of the space-charge wave. In addition, the analytic expressions of the real part and the damping rate of the wave frequency are obtained for a plasma waveguide including the influence of collision and geometric configuration. It is found that the space-charge wave has the strong decay mode in small wave numbers. In these decay modes, the damping rate increases with an increase of the collision frequency and decreases with an increase of the order of the root of the Bessel function. It is found that the damping rate of the space-charge wave increases with an increase of the radius of the plasma waveguide. It is also found that the space-charge wave is always highly damped in the propagation domain. In addition, the influence of geometric configuration on the damping rate is found to be much significant in high-harmonic cases. Graphical abstract