Apparatus for compensating for time-vibrant field interference in magnetic fields
US4788502A · kind A · utility
Inventors
Key dates
| Filing date | Aug 14, 1987 |
| Grant date | Nov 29, 1988 |
| Priority date | — |
| Expiry date | Aug 14, 2007 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH01F6/00
- WIPO fieldElectrical machinery, apparatus, energy
- WIPO sectorElectrical engineering
Abstract
An apparatus is employed to compensate for time-variant field interference in magnetic fields of electromagnets with high field homogeneity, in particular in specimen areas of superconductive electromagnets for measurements of magnetic resonance. The magnetic field that permeates a specimen area of the electromagnet is identified by means of at least one induction coil, a voltage induced in the induction coil is supplied to a control stage, and a compensating current that flows through a compensating coil that surrounds the specimen area is set by means of an output signal from the control stage. In order to be able to compensate for remote interference emanating from far outside the magnet, at least one compensating coil and at least two induction coils, or vice versa, are disposed. Disposed in the control stage is either a voltage adder, to which the induced currents of the at least two induction coils can be supplied and differently weighted, or a current divider, which supplies differently weighted compensating currents to at least two compensating coils. The induction voltages or compensating currents can be weighted as a function of frequency.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.