Superconducting switches

An electrical switch comprising:

• a length of superconducting material configured to carry a transport current, wherein the length of superconducting material has a critical current and a critical temperature;
• a first magnetic field generator configured to apply a first, constant, magnetic field to the length of superconducting material;
• and
• a second magnetic field generator configured to apply a second, time-varying, magnetic field to the length of superconducting material,
• wherein the first magnetic field generator and the second magnetic field generator are configured to be selectively controlled independently or in combination to switch the length of superconducting material between a low-resistance state and a higher resistance state,
• wherein, in the low-resistance state, magnitudes of the first magnetic field and the second magnetic field are relatively low and the transport current is substantially less than the critical current,
• wherein, in a first configuration of the electrical switch in the higher-resistance state, the magnitude of the first magnetic field is relatively high to reduce the critical current such that the transport current approaches the critical current, is substantially equal to the critical current or is greater than the critical current of the length of superconducting material,
• wherein, in a second configuration of the electrical switch in the higher-resistance state, the second magnetic field creates dynamic resistance in the length of superconducting material, and
• wherein, in a third configuration of the electrical switch in the higher-resistance state, the magnitude of the first magnetic field is relatively high to reduce the critical current such that the transport current approaches the critical current, is substantially equal to the critical current or is greater than the critical current of the length of superconducting material, and the second magnetic field creates dynamic resistance in the length of superconducting material.