Saddle Coils for Uniform Static Magnetic Field Generation in NMR Experiments

F. BONETTO; E. ANOARDO; M. POLELLO

CONCEPTS IN MAGNETIC RESONANCE PART B: MAGNETIC RESONACE ENGINEERING

John Wiley and Sons

Lugar: Hoboken, New Jersey, USA; Año: 2006 p. 9 - 19

1043-7347

The magnetic flux density field (called henceforth ``magnetic field", for the sake of simplicity) generated by a saddle coil system is numerically calculated in the whole space and experimentally tested in two different spatial planes. The uniformity of the magnetic field is studied using Taylor series expansions of the three components separately. The optimum geometry is revised and obtained from the second order Taylor expansions. The most favorable relationship between saddle coil geometric parameters is determined in case of the optimum geometry can not be achieved (because of experimental restrictions). Approximated manipulable analytical expression are obtained via fourth order Taylor expansions of the three components of the magnetic field and compared with exact expressions. Considering typical sample and coil dimensions, it is found that they differ in less than 10^(-3) within a sample region. Deviations of the magnetic field produced by an optimum compensating saddle coil system were contrasted with typical NMR field cycling magnet field inhomogeneities. Possible influences of such deviations in NMR experiments are discussed.