What provides the centripetal force for Cooper pairs flowing in a toroidal superconductor?

I asked myself this question, which led me to realize I also don't really know the answer to a more basic question: What provides the centripetal force for ordinary current (electrons) flowing in a circular wire?

Are either or both of these forces a Lorentz force, as a result of the magnetic field generated by other moving electrons/Cooper pairs? (I suspect no, since if I were to add more electrons/Cooper pairs into the conductor/superconductor, then the centripetal force on individual charge carriers will increase and their motion will follow a tighter circle, perhaps ejecting the surplus charge carriers from the conductor/superconductor. But I don't think this really happens? And this apparently fails to explain the forces experienced by charge carriers flowing in closed loops other than circles, e.g. forces that cause charge carriers to "turn the corners" in a square loop.)

These thoughts prompt the question: does the ion lattice itself exert a centripetal force? Is the mechanism by which the lattice exerts a centripetal force different for Cooper pairs in a superconductor than for ordinary electrons in an ordinary conducting wire? (I suspect some kind of "yes" to these questions, though I don't understand the mechanism by which the ion lattice would exert a force, especially for Cooper pairs in a superconductor. I figure ordinary electrons can at least "bump" themselves around the lattice in a circular wire -- which I suppose would mean that for extraordinarily narrow wires, the resistance of the wire could be a function of its geometry (!) -- but for Cooper Pairs to do so without resistance of course feels like a miracle.)

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    $\begingroup$ Well, rotating material can spin indefinitely with no dissipation in vacuum, and the centripetal force is provided by the material strength. Why would a superconducting current be different? $\endgroup$
    – lurscher
    Jan 4 at 17:05
  • $\begingroup$ @lurscher a superconducting current, or ordinary current for that matter, is composed of individual pseudoparticles or particles (Cooper pairs or electrons, for supercurrents or "ordinary" currents, respectively) which are not in bound states with the other psuedoparticles or particles. This differs dramatically from a spinning rigid object, does it not? Sometimes we imagine electrons in a conductor to be an "electron gas" that is unbound with individual ions. $\endgroup$
    – David C.
    Jan 4 at 20:08
  • $\begingroup$ @lurscher I see that I may be misled in my understanding that Cooper pairs are not in "bound states" with the other Cooper pairs. a similar question to mine in this post has been asked here: physics.stackexchange.com/q/244049/106387 $\endgroup$
    – David C.
    Jan 5 at 18:26


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