Empirical and Theoretical Analysis of B-Field Behavior in X-Y Ion Beam Steering Magnets*

The "X-Y Steering Magnet" is an essential component of beam transport systems because it can provide small corrections to the vertical and horizontal positions of the beam. Since the profile of the beam can potentially fill the physical space of the magnet, knowing the actual 3-dimentional B-field structure is important for optimizing the transport efficiency of the beam along the beam line. Although the B-field structure of X-Y Steering Magnets is academic, the TAMU Cyclotron Institute does not have empirical B-field maps of the X-Y Steering Magnets used on their beam lines. Recently, the Cyclotron Institute purchased three new X-Y Steering Magnets which need to be tested and compared to an existing X-Y Steering Magnet before being installed on the beam line. This study aims to gather empirical B-field maps from the four X-Y Steering Magnets and compare the results to theoretical predictions. The work involved assembling a 3-dimentional positioning apparatus for a gaussmeter, designing a versatile base stand for the magnets, and comparing the B-field measurements to theoretical simulations. Magnetic fields were recorded at currents of 1, 2.5 and 5 Amps, at 3 points along the z-axis, and at specific x-axis and y-axis coordinates to obtain 3-dimensional B-field maps for each magnet. The data was entered and analyzed in Microsoft Excel. The measured B-field values, and overall B-field structure agreed with the predictions made by the 2-dimesional FEMM software. However, the data also revealed a non-linear structure in the magnetic field at the center of the magnet along the z-axis coordinate, which then agreed with the simulations made by the 3-dimensional COMSOLE software. The findings of this work have enhanced our understanding of the magnetic field structure of the X-Y Steering Magnets used at the Cyclotron Institute and will contribute to an improved transport efficiency of the beams along the beam lines. Future work will involve comparing the measured trajectories of actual ion beams against theoretical predictions.