Advanced storage ring concepts for intense ion beams often require operation far outside the stability boundaries provided by Landau damping. Whether a machine can be operated in such a regime depends on the phase space dilution after saturation of the microwave instability. A Vlasov simulation model is employed to analyze the saturation mechanisms in space charge dominated coasting beams. The stabilizing effect of space charge [I. Hofmann, Laser Part. Beams 3, 1 (1985)] is addressed to fluidlike mode coupling effects.
