Saturation of turbulent energy density in longitudinal currents

The phenomenon of saturation of electrostatic turbulence level at longitudinal current passing in magnetosphere depending on j longitudinal current density is analysed. It is shown, that this phenomenon is satisfactorily explained using the concept about excitation at auroral force lines of ion-cyclotron and ion-acoustic electrostatic turbulences. If ion resonances broadening is the stabilization mechanism of ion-cyclotron instability, the dependence of turbulence level on j value corresponds to turbulent energy restriction at current increase. More intensive longitudinal currents excite the Benemann and then ion-acoustic instability in the Sagdeev mode. Resulting turbulence is nonstationary, its level decreases with the course of time. This turbulence maximal level does not depend on j current value. Corresponding evaluations of turbulence levels for both instabilities are close to the values, derived from the experiment