Title :
A permanent magnet for NMR
Author :
Battocletti, Joseph H. ; Myers, Thomas J.
Author_Institution :
Milwaukee VA Med. Center, WI, USA
fDate :
9/1/1989 12:00:00 AM
Abstract :
A 0.105-T (1050-G) whole-body permanent-magnet structure has been designed by 3-D and 2-D, finite-element analysis, constructed using simple manufacturing techniques, and passively shimmed to yield a homogeneity factor of 105 p.p.m. over a 25-cm- (10-in) diameter sphere. Ceramic type 10 magnetic material is used. An expert computer program that utilizes all the shimming data for additional homogeneity improvement has been written. The program, which includes over 1000 inhomogeneity conditions, could be used for shimming other magnet structures. Transient temperature tests show that the magnetic flux density at the center of the working air gap can change significantly in the short term, so that temperature stability of the magnet environment is required
Keywords :
CAD; biomedical NMR; electrical engineering computing; expert systems; finite element analysis; permanent magnets; 0.105 T; NMR; ceramic type 10 material; expert computer program; finite-element analysis; inhomogeneity conditions; magnetic flux density; magnetic material; passive mechanical shimming; permanent magnet; shimming data; temperature stability; transient temperature tests; whole-body imaging; working air gap; Ceramics; Finite element methods; Magnetic analysis; Magnetic flux; Magnetic materials; Manufacturing; Nuclear magnetic resonance; Permanent magnets; Temperature; Testing;
Journal_Title :
Magnetics, IEEE Transactions on
