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A Magnetic Multipole

A general magnetic multipole, i.e. a superimposed quadrupole, hexapole and octopole, is defined by the command: 9 M(AGNETIC) M(ULTIPOLE) <effective length $\ell$ of multipole in meter> <BQ in T at pole tip> <BH in T at pole tip> <BO in T at pole tip> <BD in T at pole tip> <BZ in T at pole tip> <aperture radius G0 in meter> ; [example: M   M   0.2   1.0   0   0   0   0   0.2 ;]

BQ, BH, BO, BD and BZ here are the quadrupole-, hexapole-, octopole-, decapole- and dodecapole-components of the magnetic flux density. For positive or negative values of BQ, BH, BO, BD and BZ particles with positive x-values are driven towards or away from the optic axis, respectively.
This multipole-command is also applicable for a pure quadrupole, hexapole, octopole, decapole or dodecapol. However, to save computer time, it is advisable to use in such cases the following commands:

KPII
1999-10-20