## Abstract

The excitation of low-frequency parametric instabilities by a finite wavelength pump in a system consisting of a warm electron plasma traversed by a warm electron beam is investigated in a fluid dissipationless model. The dispersion relation for the three-dimensional problem in a magnetized plasma with arbitrary directions for the waves is derived, and the one-dimensional case is analyzed numerically. For the one-dimensional back-scattering decay process, it is found that when the plasma-electron Debye length (λ _{D}^{p}) is larger than the beam-electron Debye length (λ_{D}^{b}), two low-frequency electrostatic instability branches with different growth rates may exist simultaneously. When λ_{D}^{p}≃λ_{D}^{b}, the large growth rate instability found in the analysis depends strongly on the amplitude of the pump field. For the case λ_{D}^{p} <λ_{D}^{b}, only one low-frequency instability branch is generally excited.

Original language | English |
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Pages (from-to) | 1456-1464 |

Number of pages | 9 |

Journal | Physics of Fluids |

Volume | 24 |

Issue number | 8 |

DOIs | |

State | Published - 1981 |