Ponderomotive Force of Ion Cyclotron Waves in the Pc1 Frequency Range with Magnetosonic Dispersion

Nonlinear properties of the Pc 1 geomagnetic pulsations with anomalous (magnetosonic) dynamic spectrum are studied. The nonlinear properties of the waves are reflected in the emergence of ponderomotive force proportional to the squared amplitude of the waves. Just as in the case of the Alfven waves, at small values of parameter ν 0 = ω/ω ci 0 < 0.4 (ratio of the carrier frequency to proton gyrofrequency in the equatorial plane), the ponderomotive force leads to the modification of the background plasma through increasing its density towards the equator. At ν 0 > 0.4, plasma is expelled from the equator towards the higher latitudes. The dependence of the nonlinear modification of background plasma for the different parameters of the magnetosphere is studied.