The Influence of the non-linear term in the ionic polarization drift on solitary kinetic Alfven wavest

It is shown that the nonlinear term in the ionic polarization drift has a non-negligible effect on the solitary kinetic Alfven waves (SKAW) of the rarefied type in low-β plasmas (β is the heat to magnetic energy ratio) i.e. the nonlinear term allows the existence of SKAW with both sub- and super-Alfvenic speeds in the low-β regime. This result appears to be in good agreement with satellite observations of the magnetosphere.