The effect of the magnetopause thickness on the interchange instability ofthe magnetospheric boundary

The interchange instability of the magnetospheric boundary at the subsolar point has been considered in the present paper on the basis of the magnetic gas-dynamic model (MGD approximation). The magnetopause is simulated by a thin layer of constant thickness and finite curvature radius. Two cases of changing magnetic field and plasma density at crossing the magnetopause wer e examined: (1) plasma parameters and the magnetic field are constant insid e the magnetopause and change by a jump at its boundaries, and (2) all para meters continuously vary from their values in the magnetosheath to those in the magnetosphere, In the first case, an analytical solution has been foun d, and the linearized problem of small disturbances of the magnetospheric b oundaries has been numerically solved in the second case. The growth rate o f intel change instability has been determined depending on the direction o f the interplanetary magnetic field, wavenumber, curvature radius of the ma gnetospheric boundary, and magnetopause thickness.