| 摘要 |
Within the scope of the invention, an apparatus for applying a constant magnetic field to a volume of interest (VOI) has been developed. This apparatus comprises at least one magnetic field source and a permeable yoke, which guides the magnetic flux generated by this magnetic field source into the volume of interest (VOI). In accordance with the invention, the yoke is guided through at least one closed conductor loop which can be transferred to the superconductive state so that, in the superconductive state of the conductor loop, a change in the flux through the yoke effects a current counteracting this change along the conductor loop. It has been identified that in this way the stabilizer for the magnetic field can be spaced so far apart from the volume of interest (VOI) that the field distribution in this volume is virtually no longer influenced. At the same time, the quality of the stabilization is also improved since the conductor loop is no longer subjected to the entire magnetic field prevailing in the volume of interest (VOI). The entire critical current that the conductor loop can carry is available as control range for compensating for fluctuations in the flux. In comparison with the prior art, the invention first accepts the apparent disadvantage that, in general, additional means are required for connecting the conductor loop to and fro between the superconductive state and the normal conductive state. However, this disadvantage is more than compensated for. |
