Bi

The dispersion function of a beam line is determined by the strength and placement of dipole magnets. As a consequence, dipole field errors also contribute to the dispersion function. Multipole components corresponding to a magnetic flux distribution, which can be added up are denoted by Bi and Ai. B1 corresponds to a normal dipole component, B2 to a normal quadrupole component, B3 to a normal sextupole component, A1 to a skew dipole, A2 to a skew quadrupole and A3 to a skew sectupole.