Frequency upshifting with power intensification of a whistler wave by a collapsing plasma medium

Summary form only given. Frequency upshifting using time-varying magnetoplasmas has been investigated previously. In all these cases the electron density profile was a monotonically increasing function of time. A fast profile was modeled as sudden creation of a plasma medium. The slow profile problem was solved using WKB method. The calculations showed that the power density in the frequency-shifted waves was less than one. It is known that across a temporal discontinuity in the properties of the medium, while the energy is conserved, the sum of the power densities of the new waves may be less than of greater than the power density of the source wave. The case of "greater power density in the new wave" with upshifted frequency seems to occur under the following circumstances: a right circularly polarized electromagnetic wave (R wave) is propagating in the whistler mode in an unbounded magnetoplasma. At t=0 the electron density starts decreasing and for t>0, the electron density profile is a monotonically decreasing function of time. A R wave is assumed to be propagating in the positive z direction in a spatially unbounded magnetoplasma medium. Let /spl omega//sub 0/ be the frequency of the incident wave, /spl omega//sub p0/ is the plasma frequency, /spl omega//sub b/ is the electron gyrofrequency and n/sub 0/ is the refractive index of the magnetoplasma medium existing prior to t=0. Assume that at t=0 the plasma undergoes a fast collapse which may be idealized as a sudden collapse. In the case of a sudden collapse it will be shown that the fields of the third wave are zero. In the whistler mode i.e. /spl omega//sub 0/1, E/sub 1//E/sub 0/>1, and S/sub 1//S/sub 0/>1. Thus we have a frequency upshifted wave with power intensification.