Patent ID: 7541905

Claim:
A magnet structure including a magnetic yoke comprising a pair of poles that define an acceleration chamber with a median acceleration plane, wherein the poles are joined at a perimeter and separated to form a pole gap in a central region with a peak gap of at least 37 cm between the poles, wherein each of the poles includes a pole wing that converges beyond the peak gap to produce a gap between the poles that is less than one-third the peak gap, wherein each pole is structured to shape a magnetic field in the median acceleration plane so that the magnetic field decreases with increasing radius in the median acceleration plane from an inner radius for ion introduction to an outer radius for ion extraction when the magnetic yoke is fully magnetized by a pair of magnetic coils positioned about the acceleration chamber and when a central magnetic field of at least 5 Tesla is directly generated in the median acceleration plane by the magnetic coils, and wherein the magnetic yoke further comprises localized magnetic tips positioned circumferentially on the upper and lower pole wings.