This paper describes a method to assess the electromagnetic characteristics of a superconducting ceramic material. YBa2Cu3O7-d ceramic samples have been made in the form of hollow cylinders with the standard 4 terminal configuration for measurement of the critical current (Ic) attached to the outer surface. An additional wire carries a second internal current (Iint) along the central axis. Ic can thus be modulated by Iint. In particular, an increase in Ic can be achieved by directing Iint in the opposite direction to the cylinder current in order to compensate the self-generated magnetic field. The Ic-Iint characteristic can be described by a critical state model where we assume a linear dependence between the local critical current density (jc) and the local magnetic field (H) for the superconducting polycrystalline material. Based on this linear model the experimental data for a given sample can be analyzed to extract two parameters: the maximum local critical current density (j0) and the local magnetic field (H0) for which jc should vanish. The best sample yielded j0 = 1023 A cm-2 and H0 = 4450 A m-1.
|Number of pages||9|
|Journal||Physica C: Superconductivity and its Applications|
|Publication status||Published - 1 Feb 2001|