Thank you marcusl, that is very helpful.
Does a critical field exist for a zero-resistance (not superconducting) cylinder? Hall (1st ed Manchester) p264 suggests this is the case. Why?
Cool a cylinder made from a Type I superconducting material below the superconducting transition temperature.
Apply a magnetic field parallel to the cylinder. The cylinder expels the flux.. up until the field reaches a critical value.
Why does a critical value exist? That is, why doesn't...