Autoresonant BGK Modes

Coherent electron phase-space structures are formed and controlled in plasmas by adiabatic nonlinear phase locking (autoresonance) with a chirped frequency driving wave. The process involves dragging a low density region in phase space into the bulk of the distribution via persistent Cherenkov-type resonance. This perturbation in electron density leads to creation of electrostatic self-field (BGK mode) in the plasma. A simplified kinetic theory of this excitation process is developed in cases of flattop [1] and Gaussian velocity distributions. The self-field dependence on the driving frequency and plasma parameters is discussed and theoretical predictions are compared with computer simulations. [1] L. Friedland, P. Khain, and A.G. Shagalov, Phys. Rev. Lett. \textbf {96}, 225001 (2006).