Stabilization and tuning of persistent currents using variable inductance
AssigneeThe Regents of the University of California
InventorLucas Brouwer
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Abstract
An alternative approach to flux pumping in superconducting devices is described for fast and extremely precise tuning of the current during persistent mode operation. Rather than bringing in new flux from outside the circuit, the alternative approach stores a small flux in a tunable inductor (also referred to herein as a “flux bank”) at the initial point of powering. Flux can be transferred back and forth from this bank to the main coil by simply changing the inductance of the bank. This allows for fine and fast adjustments of the persistent current without the use of thermal switches found in other approaches (which limit the adjustment speed and accuracy).
Claims20
An apparatus for storage of magnetic flux at cryogenic temperatures comprising:
- (a) a variable inductor;
- (b) wherein the variable inductor is configured for storing a magnetic flux in situ within a cryogenic system configured for a persistent magnetic operation mode;
- (c) wherein said variable inductor operates as a flux bank which is charged at the initial point of powering the circuit;
- and
- (d) wherein said variable inductor performs flux pumping to a closed superconducting magnetic circuit through inductive transfer, without the need of breaking and closing superconducting connections to move flux into the closed superconducting magnetic circuit.
A method for maintaining a persistent magnetic field in a cryogenic apparatus, comprising:
- (a) providing a variable inductor in series with a main inductor to create a superconducting circuit;
- (b) inducing a persistent magnetic field within the main inductor;
- (c) measuring a field strength of the persistent magnetic field;
- (d) controlling the persistent magnetic field strength by changing an inductance of the variable inductor which operates as a flux bank which performs flux pumping through inductive transfer;
- (e) whereby the persistent magnetic field is maintained at a controlled level in response to shifting flux to and from the variable inductor and main inductor.
Dependencies are inferred from the claim text.