Interesting idea, but I am not sure that the structures would be equivalent: in the "classic" method, an explicit sensor located at the center of the device ensures a zero magnetic field there, but with the superconducting coils there is no explicit sensor: the coils themselves act as an implicit sensor and create an opposing field in their vicinity, but does this imply that the field in the center region is zero?
That is something one needs to think about.
If it is workable, there is no need for actual superconductors: the drive amplifier can have a negative resistance exactly equal to the copper resistance.
Copper has a significant tempco, but it would be possible to embed two compensating windings wired in opposition in the coil, and they would track the temperature very accurately.
If the tracking accuracy is +/-0.1°C, the resistance deviation would be 0.04%, allowing a safe compensation down to 0.1%.
For the degaussing loop I took for example, this would push the low frequency cutoff down to 0.5Hz, which would be sufficient for 50Hz applications
That is something one needs to think about.
If it is workable, there is no need for actual superconductors: the drive amplifier can have a negative resistance exactly equal to the copper resistance.
Copper has a significant tempco, but it would be possible to embed two compensating windings wired in opposition in the coil, and they would track the temperature very accurately.
If the tracking accuracy is +/-0.1°C, the resistance deviation would be 0.04%, allowing a safe compensation down to 0.1%.
For the degaussing loop I took for example, this would push the low frequency cutoff down to 0.5Hz, which would be sufficient for 50Hz applications