Shimming device for superconducting magnet

Abstract

A shimming device sequentially records a history of conducted shim setting, momentarily dynamically calculates compensation values corresponding to the record by the aid of a characteristic function, and dynamically controls the shim coil by the aid of the compensation values thus obtained, to thereby compensate magnetic field fluctuation of a superconducting magnet which is attributable to the setting of the shim, and stabilizes the magnetic field in an NMR superconducting magnet. This device includes a shim setting recorder () that records a set value of the shim, a type of set operation, the operation amount of the setting, and a time at which the setting is conducted, in association with each other for each setting; generating compensation function supply () that supplies a generating compensation function that is a function having the type of the operation, the operation amount, and the amount of time as factors, and is set so as to approximately compensate a magnetic field fluctuation attributable to individual setting; compensation value computer () that refers to the generating compensation function supply () and the shim setting recorder (), computes a compensation value at the time t by the aid of a compensation function that is configured by, and outputs the computation result; a shim coil driver () that drives the shim coil () by the aid of a sum of the compensation value obtained by the compensation value computer (), and a latest set value.