RAPID COMPUTATION OF STATIC FIELDS PRODUCED BY THICK CIRCULAR SOLENOIDS

A straightforward method is proposed for computing the magnetic field produced by a circular coil that contains a large number of turns woun d onto a solenoid of rectangular cross section. The coil is thus appro ximated by a circular ring containing a continuous constant current de nsity, which is very close to the real situation when sire of rectangu lar cross section is used. All that is required is to evaluate two fun ctions, which are defined as integrals of periodic quantities; this is done accurately and efficiently using trapezoidal-rule quadrature. Th e solution can be obtained so rapidly that this procedure is ideally s uited for use in stochastic optimization, An example is given, in whic h this approach is combined with a simulated annealing routine to opti mize shielded profile coils for NMR.