Transport of the electromagnetic field energy through a plasma-like medium near cut-off

Abstract

The cut-off of propagation of electromagnetic waves in a plasma-like medium is a well-known phenomenon; when the frequency of the wave is below the cut-off frequency, which is determined by the Bohm-Gross dispersion relation, the wave is reflected leaving behind only an evanescent wave, which does not convey any electromagnetic energy. However, the dispersion relation describing the cut-off applies in a stationary state, whereas near the cut-off condition there is a long transient period before the system reaches a steady state. During this transient period, a significant amount of the field energy is transported through the medium near cut-off. The transient behavior of the field near cut-off has not been illuminated before. In this presentation, we demonstrate, both theoretically and by simulations, that the electromagnetic energy can transport through a plasma-like medium near cut-off over substantial distances.