Pinning by a Macroscopic Spherical Cavity in a Type II Superconductor

Abstract

The magnetic field created by a vortex line located near a macroscopic spherical cavity as well as the ma.gnetic field within the superconductor are calculated by solving London equations using the generalized spherical function technique. The interaction energy between the flux line and the cavity and consequently the pinning force are also calculated. It is shown that one possible cause of the pinning is that an attractive image force exists a t the superconductor sphere boundary.Sowohl das durch eine in der NLhe eines makroskopischen spharischen Hohlraums lokalisierte Wirbellinie hervorgerufene magnetische Feld als auch daa magnetische Feld innerhalb des Supraleiters werden durch Losung der Londongleichungen mit der Technik der verallgemeinerten spharischen Funktion berechnet. Die Wechselwirkungsenergie zwischen der FluBlinie und dem Hohlraum und folglich die Anhaftkraft werden ebenfalls berechnet. Es wird gezeigt, daB ein moglicher Grund fur das Anhaften die Existenz einer anziehenden Bildkraft an der SupraleiterKugelgrenze ist.

Pinning of a Curved Flux Line by Macroscopic Inclusions in a Type II Superconductor

“…If the straight F L intersects the xy plane a t (R, 0, 0 ) , i.e. Po = 1 2 and po -0, we get the same results previously obtained in [4].…”

“…The interaction between a straight P L and a cylindrical normal inclusion in type I1 superconductors was considered in [2, 31 while the interaction with a macroscopic spherical cavity was treated in [4]. Flux pinning is experimentally determined from critical current and flux penetration profile measurements.…”

“…The procedure of calculations of the magnetic fields, energy, and pinning force is carried out in the same manner as in [4]. However, in the present case, the curved FL is described by the locus of its 7-singularity, i.e.…”

Effect of extremely fine Y2BaCuO5 precipitates on the critical current density of melt-processed YBa2Cu3Ox

“…The interaction energy of a vortex and a cavity and the resulting elementary pinning force has been calculated by various researchers. 56,63,[87][88][89][90][91][92][93][94][95] In particular, Friedal et al, 87 Silocox et al, 56 Shehata, 89 and Daemen et al 89,90 have estimated the pinning force associated with a spherical cavity. Interaction between a cylindrical cavity with axis parallel to that of a flux line has been studied by Mkrtchyan et al, 92 which was further modified by Timms et al 93 In all of these estimations the pinning force is assumed to be originated from the socalled magnetic interaction.…”

Magnetic Pinning Interaction of a Type‐II Superconducting Cylinder

“…The interaction between a straight FL and a cylindrical normal inclusion in type-I1 superconductors was considered in [ 7 , 81 when the interaction of a straight FL [9] (or ourved PT, [ 101) with a macroscopic spherical inclusion was considered.…”