Absolute parametric instability in a nonuniform cylindrical plasma waveguide

The paper reports an analysis of the effect of spatial plasma nonuniformity on the parametric instability of electrostatic waves in magnetized cylindrical waveguides subjected to an intense HF electric field. It is shown that allowance for the spatial nonuniformity leads: (1) to localization of an unstable wave in a finite region of the plasma volume, (2) to an increase in the threshold value of the pump wave amplitude above which parametric amplification occurs and (3) to a decrease in the value of the growth rate of the unstable waves.