ELECTROMAGNETIC EXPULSION FORCE IN COSMIC PLASMA

Electromagnetic expulsion acts on a body submerged in a conducting flu id traversed by an electric current and a, magnetic field (provided th e Lorentz force in the vicinity of the body is not zero). The effect r esults from the difference of electric conductivities inside and outsi de the body and is the MHD counterpart of the Archimedean force. In th is paper the dimensionality consideration and energy analysis are used to determine the expulsion force in the case of large magnetic Reynol ds numbers, that is important for astrophysical applications. The cons equences of electromagnetic expulsion are shown to be observable in so lar prominences; here it can balance the gravity and can generate fast vortex flows inside them and in their vicinity. Possible observationa l tests of the effect are discussed.