A magnet system of a magnetic resonance apparatus for generating a magnetic field which is homogeneous and temporally highly stable within a volume under investigation and which extends along a z-axis, with a superconducting magnet coil (3) which is disposed in a cryostat (1) and with a periodically operated refrigerator (2) having a magnetic regenerator material which is disposed in a regenerator housing (5) within the cryostat (1) in the stray field of the magnet coil (3), and which is provided with a device (4) for shielding or compensating a magnetic disturbing field in the volume under investigation generated by the periodic operation of the refrigerator (2) due to regenerator magnetization changes is characterized in that the regenerator housing (5) is surrounded by a compensation coil arrangement (4) which can be superconductingly short-circuited and which is made from a plurality of conductor loops (6, 7a, 7b) which are separately short-circuited during measurement to keep a plurality of magnetic fluxes through these conductor loops (6, 7a, 7b) constant in the superconductingly short-circuited state. A magnet system of this type facilitates effective compensation of the disturbing fields caused by a magnetic regenerator material at the location of the volume under investigation.

 
Web www.patentalert.com

> Medium voltage vacuum contactor

~ 00358