A non-destructive, non-contact, quality test of critical current for Ag-BiSCCO tape

An accurate noncontact method of characterizing Ag-BiSCCO tape is reported, using the trapped field, B_t, of a field-cooled tape. The dimensions of the tape make it possible to calculate in closed form a very simple expression, relating trapped field to transport current. Short lengths of tape, 4 cm, are used to experimentally confirm the model. The model applies to any length of tape for which length is greater than 5 times the tape width. A schematic of a proposed test apparatus is presented which should permit on-line testing for magnitude of the current, and for cracks, while the tape is in motion during production.