Current between supeconducting rings

How to calculate the current between two superconducting rings with radius r separated by a distance d?

Please note that being unfamiliar to the concept of superconducting rings, I can't approach this problem. It would also be useful if anyone tells me which special property of superconductors can be used here.

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Please note that the superconducting rings will be placed in such a way that one ring is vertically above the other, so the line joining the centers of the rings will actually be the axis of the cylinder formed by joining the rings. –  helloworld Apr 22 '13 at 2:11
The problem is ill posed since you could start with two distant rings with whatever current you like and bring them into your configuration. There will be some induction currents generated when you do this, but since you can start with arbitrary currents I'd imagine that there are many solutions. Can you tell us more about your problem? –  Michael Brown Apr 22 '13 at 8:08
@ Michael Brown, I cannot comment so I am writing it as an answer. Suppose two identical superconducting rings are brought very close to each other, and then the current between them is I. Given this information, how can we find the current between them when they are at some fixed distance apart? I would prefer some hints/properties of superconductors rather than the fully worked solution itself. –  user23464 Apr 22 '13 at 10:41