ON THE MAGNETIC-MOMENT INDUCED IN THIN SUPERCONDUCTING DISCS

Results are presented of model calculations on the surface current dis tribution on thin superconducting oblate spheroids in low perpendicula r magnetic fields. The total magnetic moment is practically independen t of the thickness of the spheroid. The calculated moment agrees well with the moment measured on thin superconducting discs. With the expec tation of a similarity in the current distribution, the latter is calc ulated for the simpler model. The results show that for spheroids, in the region up to 99% of the major semiaxis R, the current density dist ribution is practically independent of the thickness of the spheroid. In the outer, 1% of R, region the current density becomes higher as th e spheroid becomes thinner but in such a way that the moment contribut ion, 21% of the total moment, is also practically independent of the t hickness of the spheroid. The current density comes into play when lim itations to critical values are considered.