Nonlinear Evolution and Saturation of an Unstable Electrostatic Wave
CALIFORNIA UNIV LOS ANGELES PLASMA PHYSICS GROUP
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The nonlinear development and saturation of a single Langmuir wave driven unstable by a gentle bump in the tail of the distribution function in a collisionless plasma is studied by treating the resonant particles numerically. Over a wide range of parameter values, the amplitude of the potential Phi is found to saturate at such a level that the ratio g OmegabGamma0 approximately equals 3.2, where Omegabek squaredPhim is the bounce frequency of the trapped particles in the wave trough and Gamma 0 is the linear growth rate, approximately given by the classical Landau value. In view of the importance of inverse Landau damping for many instabilities, this work should have wide applicability and the results should be suitable for direct experimental tests.
- Fluid Mechanics
- Plasma Physics and Magnetohydrodynamics