From Wikipedia: "Any change to the current through the magnet must be done very slowly, first because electrically the magnet is a large inductor and an abrupt

From Wikipedia: "Any change to the current through the magnet must be done very slowly, first because electrically the magnet is a large inductor and an abrupt current change will result in a large voltage spike across the windings, and more importantly because fast changes in current can cause eddy currents and mechanical stresses in the windings that can precipitate a quench [...]. So the power supply is usually microprocessor-controlled, programmed to accomplish current changes gradually, in gentle ramps. It usually takes several minutes to energize or de-energize a laboratory-sized magnet." https://en.wikipedia.org/wiki/Superconducting_magnet https://en.wikipedia.org/wiki/Superconducting_magnet