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Abstract

The Tritium-Helium-Trap-Experiment (THe-Trap) at the Max-Planck-Institut für Kernphysik in Heidelberg is a Penning-trap mass spectrometer which aims to measure the mass ratio of tritium to helium-3 with a relative precision of 10^-11. To correct for inhomogeneities of the magnetic field a set of correction coils is installed on the trap envelope. The magnetic field of extended coils is derived theoretically and checked with a simulation of the coil geometry in COMSOL Multiphysics. The series coefficients at the precision trap center of the correction coils are calculated in accordance to the design values. Deviations of these components are dominated by the misalignment of the coils relative to the trap center. The magnetic field is calculated on and off axis, the series coefficients are in particular also determined in the storage trap center. Mechanical influences due to the external magnetic fields are investigated and found to be mostly harmless to the setup. At last an alternative coil geometry, which offers better spatial homogeneity of the coefficients, is discussed.