A simple model for frequency up-conversion in linear time-variant gaseous plasmas

We present a simple model to estimate electromagnetic wave frequency up-conversion resulting from rapidly forming gaseous plasma slabs. Such a model aids in the interpretation or planning of realizable laboratory experiments, where the plasma is neither formed instantaneously nor infinite in spatial extent. The model uses, as a basis, the behavior of an unbounded plasma when the plasma forms over extended times and considers slab boundary conditions to estimate optimum transmitted sampling windows that capture the frequency spectra of the converted waves. The results of this model are compared to exact solutions using finite difference time domain calculations, confirming its effectiveness as a tool for understanding the fundamental nature of the wave-plasma slab interactions and for planning and interpreting experimental results.