The spatial structure of ULF-waves in the equatorial resonator localized at the plasmapause with the admixture of the heavy ions

• The ULF-waves are trapped in the equatorial resonator along the magnetic field.
• The resonator appears due to an admixture of heavy ions in magnetosphere plasma.
• The waves are trapped in the waveguide localized near the center of plasmapause.
• The wave eigenfrequencies are quantized.
• The frequency depends on both the wave parallel structure and perpendicular one.

The paper is devoted to the spatial structure of ULF (ultra-low frequency) Pc1 oscillations with the admixture of heavy ions taken into account. Due to dip of the Alfvén velocity in the plasmapause region and the admixture of heavy ions, the wave is located in the two-dimensional resonator located near the plasmapause on the radial coordinate and near the magnetic equator along the magnetic field line. For the purposes of a qualitative analysis of the parallel resonator, the WKB approximation in the coordinate along the magnetic field line was used to obtain the wave eigenfrequencies.