An Optimization Technique for Computing Chromatic Corrections in Heavy Ion Focussing Systems

An optimization algorithm is described for computing field strengths for a set of corrective sextupole magnets in a heavy ion focussing system. Initial results are presented which show that, in some cases, the beam transmission through a 1 mm pellet canbe increased from an uncorrected value of about 60% to over 90%. The method should be useful for systems where, due to constraints or the presence of a number of abberations, no straight-forward theory exists for directly computing the field strengths.