The double parametric instability in magnetized plasma

The possibility of reducing the threshold of the low-frequency parametric instability in a magnetized plasma by means of the double parametric resonance has been investigated. One finds that, beside the lowering of the instability threshold for γ >> Ω (already reported for an unmagnetized plasma) an important reduction of the threshold - with a corresponding increase in the instability increment - results for a magnetized plasma for γ << Ω. (author)