CRITICAL CURRENTS IN NORMAL CONDUCTORS

It is shown that in a normal conductor the value of a current that gen erates a magnetic pressure equal to the critical pressure may be consi derably lower than it is generally considered. The lower value of the critical current occurs due to the shift of the whole curve of phase e quilibrium in the presence of strong electric current. This shift aris es due to the additional work performed against ponderomotive forces w hich prevents from the formation of the nucleus of a phase with a lowe r value of electric conductivity. In case of the Van der Waals model o f the critical state the value of the critical current calculated taki ng into account the shift of the phase equilibrium curve is by factor 2-3 less than the critical current determined when this effect is negl ected.