NUCLEAR MAGNETIC RESONANCE APPARATUS AND METHOD FOR GENERATING AN AXISYMMETRIC MAGNETIC FIELD HAVING STRAIGHT CONTOUR LINES IN THE RESONANCE REGION

摘要

The present invention is directed to a nuclear magnetic resonance apparatus and method for generating an axisymmetric magnetic field having long, straight contour lines in the resonance region. A magnetically permeable member is used to shape th e static magnetic field generated by an array of permanent magnets. The magnetically permeable member minimizes variations of the static magnetic field in the formation du e to vertical motion of the apparatus while obtaining a nuclear magnetic resonance measurement. Further, the magnetically permeable member may minimize variations of the static magnetic field in the formation due to lateral motion of the apparatus while obtaining a nuclear magnetic resonance measurement.