A water bag model of driven phase space holes in non-neutral plasmas

The formation and control of stable multiphase space hole structures and the associated Bernstein-Greene-Kruskal modes in trapped pure ion plasmas driven by an oscillating, chirped frequency perturbation are considered. The holes are formed by passing kinetic bounce resonances ωd =nπ uL in the system, u and L are the longitudinal velocity of the plasma species and the length of the trap, and n is the multiplicity of the resonance (the number of the phase space holes). An adiabatic, quasi-one-dimensional water bag model of this excitation for an initially flat-top distribution of the ions in the trap is suggested, based on the isomorphism with a related problem in infinite quasineutral plasmas. A multiwater bag approach allows us to generalize the theory to other initial distributions. Numerical simulations yield a very good agreement with the theory until the coherent phase space structure is destroyed due to the resonance overlap when the decreasing driving frequency passes a critical value estimated within the water bag theory.