Apparatus for improving the homogeneity of a magnetic field

Claim 1

APPARATUS FOR IMPROVING THE HOMOGENEITY OF A CERTAIN VOLUME OF MAGNETIC FIELD BY REMOVING A PARTICULAR UNDESIRED FIELD GRADIENT INCLUDING, ELECTRICALLY CONDUCTIVE MEANS FOR PROVIDING A PLURALITY OF SPACED APART CURRENT PATHS IN EACH OF A PAIR OF ESSENTIALLY PARALLEL PLANES, THE SPACING BETWEEN SAID CURRENT PATHS BEING LARGER THAN ANY DISTANCE TRAVERSING THEIR CROSS SECTION, SAID PAIR OF PLANES POSITIONED ON OPPOSITE SIDES OF THE VOLUME OF MAGNETIC FIELD TO BE CORRECTED SO AS TO DEFINE A GAP THEREBETWEEN, SAID ELECTRICALLY CONDUCTIVE MEANS INE ACH OF SAID PLANES BEING THIN IN THE DIRECTION TAKEN ACROSS THE GAP SO THAT SAID SPACED APART CURRENT PATHS LIE ENTIRELY IN SAID PAIR OF ESSENTIALLY PARALLEL PLANES AND LYING ON OPPOSITE SIDES OF A PLANE THROUGH THE VOLUME OF MAGNETIC FIELD AND PERPENDICULAR TO SAID PARALLEL PLANES, SAID ELECTRICALLY CONDUCTIVE MEANS BEING CONNECTED SO AS TO PROVIDE WHEN ENERGIZED IN EACH OF SAID PARALLEL PLANES TWO OPPOSING DIRECTIONS OF CURRENT FLOW ON ONE SIDE OF SAID PLANE THROUGH SAID VOLUME OF MAGNETIC FIELD AND TWO OPPOSING DIRECTIONS OF CURRENT FLOW ON THE OTHER SIDE OF SAID PLANE THROUGH SAID VOLUME OF MAGNETIC FIELD, AND SAID ELECTRICALLY CONDUCTIVE MEANS BEING DISPOSED SO THAT WHEN ENERGIZED THE CURRENTS FLOWING IN OPPOSING DIRECTIONS WILL FLOW SUBSTANTIALLY PARALLEL TO SAID PLANE THROUGH SAID VOLUME OF MAGNETIC FIELD.