LAUSR

This paper is concerned with the structure of the ion-ion hybrid (IIH) waves in the multicomponent magnetospheric plasma in the dipole geomagnetic field model. Like the Alfv\'en waves, in the IIH waves the field line can oscillate in different directions: in the azimuthal direction (the toroidal modes) and in the radial direction (the poloidal modes). Contrary to the Alfv\'en waves, in the IIH waves only the equatorial part of the field line can oscillate, since due to the heavy ions admixture the IIH are trapped in the resonator in the vicinity of the geomagnetic equator. The equatorial localization of the waves allowed to calculate the parallel structure of the toroidal and poloidal IIH modes analytically. It was found that the toroidal and poloidal modes have slightly different structures. Their frequencies are slightly different as well. The difference between toroidal and poloidal frequencies (the polarization splitting) is small with respect to the basic harmonics of each mode. It was found that IIH modes have considerable comressional component of the wave's magnetic field.