Parametric Excitation of Plasma instabilities by two Monochromatic Pump waves

Abstract

AbstractThe dispersion characteristics of a plasma in a pump field 𝔈(t) = 𝔈 sub ω0t + 𝔈1 sin ω1t are considered. Firstly we assume, that the second wave is weak (|𝔈1| ≪ |𝔈0|) and the frequency ω1 is near sω0(ω1 = sω0 + Ω,Ω ≪ ω0). We obtain the dispersion equation, describing the parametric coupling of the waves driven by the strong field 𝔈0 sin ω0t under the resonance condition ω0 ≈ ωLe/P and derive the expressions for the growth rates (ωLe is the electron LANGMUIR frequency; s, p are integers). In the second part it is shown, that a strong field 𝔈1 with a frequency ω1 much larger than ω Le(ω Le ≈ pω0) stabilizes the plasma; the growth rates are reduced and the frequency region of the parametric instability is contracted.