I Effect of Fringe Fields for a Bending (Dipole) Magnet on Field Integral?

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Modeling a bending magnet for a magnetic spectrometer using FEMM reveals concerns about the impact of fringe fields on the field integral ∫B ds. Initially, a hard edge scenario was analyzed without fringe fields, leading to a baseline understanding of the magnetic field. When fringe fields were introduced, there was uncertainty about whether the field integral would increase or decrease. The initial hypothesis suggested that the integral would decrease due to a reduction in the normal B field when extending the path length into fringe regions. This discussion highlights the complexities of accurately modeling magnetic fields in bending magnets.
rubixx14
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I'm doing some modeling of a bending magnet in FEMM, to use as a magnetic spectrometer, and came across the following equation:
Energy_spectrometer_equation_cropped.png

with the setup of the magnetic spectrometer similar to the following figure:
Energy_spectrometer_figure.png

At first I modeled a hard edge scenario in a 2D cross section, where no fringe fields had been considered, and then I began to look at adding the fringe fields. My question relates to the field integral of ∫B ds and how it changes (does it increase or decrease?) when you add in the fringe fields? My initial thinking is that the integral would decrease, since the normal B field I acquired from my model decreased when I extended the path length out to include the fringe regions, but I'm not entirely confident on my conclusion.
 
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