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Accuracy of the Fill Factor Formula in the Halbach System

F Balci1, N Dogan2, A Bingolbali1*, (1) Yildiz Technical University, Istanbul, TR, (2) Gebze Technical University, Gebze-Kocaeli, TR


(Sunday, 7/12/2020)   [Eastern Time (GMT-4)]

Room: AAPM ePoster Library

Purpose: Halbach magnets are generally used in direct current motors, magnetic bonding devices and especially in the field of medical imaging such as MPI and MRI techniques. Many studies have been done on Halbach magnets because magnetic flux density is the more sinusoidal and unwanted background of such magnetic fields are much lower. In literature, the effect of magnet length, magnet residual factor, a radius of Halbach system and filling factor parameters in Halbach design have been investigated. In this study, a new mathematical model was developed by optimizing the fill factor equation. In this way, it can be understood exactly the value of a designed cylindrical Halbach system in terms of filling factor.

Methods: Numerical calculation of the filling factor model we developed was tested for its accuracy and the Comsol Multiphysics 5.4 simulation program was used to measure its optimization. Comparison of the old and new models in 4 magnet systems was made in cylindrical Halbach system at different values of the parameters of Br factor, magnet length, system radius, and fill factor since these parameters affect the performance of the cylindrical Halbach system in terms of creating magnetic flux density at the center.

Results: Our model for the fill factor formula showed that the magnetic flux density of the system was produced approximately 17.6% more accurately than that old model in literature in the 4 magnet system. This optimization rate did not change significantly by the change of Br factor and magnet length. However, this rate increases with increasing system radius and filling factor in the Halbach system.

Conclusion: The calculations made show how far the magnetic flux density, which should actually be exactly correct, is calculated from its real value. Thus, our fill factor model removes such a gap in the literature.

Funding Support, Disclosures, and Conflict of Interest: This work was supported by the Scientific and Technological Research Council of Turkey under Grant TUBITAK 115E776 & 115E777.


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