| 摘要 |
A magnetic field generation system can comprise first (28a) and second (28b) magnetic flux concentrators each spaced apart to form a sample volume (30). The first (28a) and second (28b) magnetic flux concentrators can be formed of a material having a magnetic field saturation. A first set of auxiliary permanent magnets (10a, 10b) can be symmetrically oriented about a portion of the first magnetic flux concentrator (28a) and can be in substantial contact with the first magnetic flux concentrator. Similarly, a second set of auxiliary permanent magnets (1 Oc, 1 Od) can be symmetrically oriented about a portion of the second magnetic flux concentrator (28b) and can be in substantial contact with the second magnetic flux concentrator. Generally, the first set (10a, 10b) and second set (10c, 10d) of auxiliary permanent magnets can be remote from the sample volume (30). Each of the first set and second set of auxiliary permanent magnets can be oriented in a magnetically repulsive orientation with respect to at least one other member of their respective sets. The first (10a, 10b) and second (10c, 10d) sets of auxiliary magnets can be magnetically associated via the first (28a) and second (28b) magnetic flux concentrators. The present invention can further be configured to allow variation of the magnetic field strength across the sample volume by disrupting the field flux across the magnetic flux concentrators. This can be accomplished by orienting one or more magnetically soft shunts (38) in a sufficient proximity to at least one of the magnetic flux concentrators (28a, 28b).
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