Patent ID: 6014069
Filing Date: 2000-01-11
Classification: G01R

Abstract:
In a superconducting magnet suitable for magnetic resonance imaging and including a plurality of main magnet coils and magnet field correction coils in a cryogen vessel and surrounding an imaging bore; a magnetic field correction coil control for adjusting correction coil current flow to improve the homogeneity of the magnetic field in said imaging bore including:a variable current source external to said cryogen vessel selectively connected through no more than 3 leads passing through said cryogen vessel to said main magnet coils and said correction coils for introducing a current flow in said coils for superconducting operation; andswitching means to selectively divert said variable current source to said magnetic field correction coils to cause a controlled superconducting current flow through said magnetic field corrections coils;said switching means including selectively operated shunts across a plurality of said magnetic field correction coils to connect selected coils in circuit with said variable current source;whereby the number of said leads between said power supply and said coils and their associated thermal loss is minimized.