This chapter assumes that the parameters of the magnetoplasma medium change slowly enough that an adiabatic analysis can be made. The objective is to determine the modifications of the source wave caused by the time-varying parameters. The chapter illustrates such an analysis for a source R wave. The starting point for the adiabatic analysis of the R wave in a time-varying space-invariant magnetoplasma medium is represented as an equation. The chapter looks at the adiabatic transformation of the whistler wave by a collapsing plasma medium. It presents equations that show that the whistler wave can have a substantial frequency upshift with power intensification of the signal. The whistler wave is converted into a wiggler magnetic field.