Measurements of the force between superconducting rings and calculation of the induced currents

Measurements of the currents induced in coaxially confronted superconducting rings

“…As it may be seen, on approaching the rings the currents increase above the initial currents (that are the critical currents for non-interacting rings). This increase is below the one obtained in previous measurements [3] because in this work the approach of the rings is limited by the greater height of the Y35x10x12 rings and the presence of the loop for the magnetic flux density measurements. Here we plot the data for only two examples of each type of confronted rings to better illustrate the agreement with the currents derived from equation (5) for the mutual inductance (solid lines).…”

“…For instance, the maximum applicable current to bar-shaped superconductors can be increased with samples threaded axially with an external wire in a counter-current setup which kept low the self-field [2]. A similar effect can be achieved by using ring-shaped samples [3]. Two current-carrying superconducting rings coaxially confronted behave like magnets that can either attract or repel each other depending on current direction trough each ring.…”

“…When the rings are bring closer the effective reduction of the self-field allows to induce in both rings persistent currents well above the maximum applicable current (the critical current) to non-interacting rings, i.e., rings far enough apart. Currents as high as the own depairing current may be induced in the case of thin-film rings [3]. When the currents can be assumed to be uniformly distributed in the rings cross-section their magnitude can be determined from the rings' mutual inductance [3] calculated in turn by using widely reported expressions [4][5][6][7].…”

“…Currents as high as the own depairing current may be induced in the case of thin-film rings [3]. When the currents can be assumed to be uniformly distributed in the rings cross-section their magnitude can be determined from the rings' mutual inductance [3] calculated in turn by using widely reported expressions [4][5][6][7]. However, this procedure is no longer valid if the currents are non uniformly distributed.…”