The magnetic field of a coil depends on the current, and the number of turns. If you have a sufficiently thin superconductor, and keep below the critical curren

The magnetic field of a coil depends on the current, and the number of turns. If you have a sufficiently thin superconductor, and keep below the critical current density, you can ramp up the number of turns until you reach the physical space limitations. When you're working with a copper conductor, the thinner the wire, the higher the resistance, and you trade off turns for conductance (1/resistance). Thus, a superconductor offers the ability to put many more turns, or much higher current, into a given volume. You're limited with steel cores as to the maximum magnetic flux, but you could get the same flux with much lower power levels using superconducting coils. Alternatively, you could redesign your motor or actuator to be a coreless design, and you can then use much, much higher magnetic fields (up to the critical field of the superconductor).