Variable impedance device with integrated refrigeration

A method of varying a magnitude of current, comprising:

• maintaining a first bus bar at a first temperature using a first refrigeration system;
• maintaining a variable impedance component that is at least partially made of a material that is superconducting below a critical temperature at a second temperature, the first temperature being between 300K and the critical temperature and the second temperature being below the critical temperature;
• passing current between the first and a second bus bar through the variable impedance component connected between the first and second leads;
• and
• increasing an impedance of the variable impedance component so that the current switches from superconducting current to resistive current through the variable impedance component.

A variable impedance subsystem comprising:

• at least a first configuration including:
• a cryocooler having a heat exchanger with a fluid passage formed therein, the fluid passage having first and second portions, each portion being in the form of a respective coil;
• an expansion valve connecting the first and second portions;
• and
• a variable impedance component on the cryocooler, the variable impedance component at least partially made of a material that is superconducting below a critical temperature.

A method of making a variable impedance subsystem, comprising:

• forming a channel in a body of the cryocooler;
• forming an expansion port in the channel;
• and
• securing a capping component over the channel so that the channel and a surface of the capping component form a passage having first and second portions with the expansion port connecting the portions;
• and
• depositing a material on the cryocooler, the material being superconducting below a critical temperature.

A variable impedance subassembly comprising:

• a plurality of cooled variable impedance configurations adjacent one another, each configuration including:
• a heat exchanger;
• and
• a variable impedance component against the heat exchanger, the variable impedance component being made of a material that is superconducting between a critical temperature and the heat exchanger being configured to cool the variable impedance component to below the critical temperature,
• at least one electrically conductive link connecting the variable impedance component of a first of the configurations with the variable impedance component of a second of the configurations.