Design and Development of a Helmholtz Pair System for Production of a Low-Magnetic Field of up to 7.5 mT

Abstract

In this study, the design, numerical modelling, and construction of various Helmholtz pair coil systems were investigated to produce a homogeneous magnetic field. The magnetic field was simulated using three different Helmholtz coil systems including 2-coil, 3-coil, and 4-coil combinations in order to optimize the field homogeneity and strength over a region of interest that consists of a cylindrical geometry with a height of 700 mm and a diameter of 90 mm. The simulated magnetic field created by the 4-coil system was found to be more homogenous than 3-coil and 2-coil systems over the region of interest. The 4-coil system was constructed and tested by using two commercially available low-power (P=600 W) DC power supplies. For further optimization, the number of turns and diameter of coil elements were simulated. The optimum number of turns and elements were determined to be 140 and 80 turns for the outer pair and inner pair of the 4-coil system, respectively. Finally, the produced magnetic field strength was measured using a hand-held gaussmeter and compared to the simulated magnetic field. We found that the system can produce a magnetic field of B=7.5047 ± 0.0562 mT, and the correlation between simulated and measured magnetic fields were calculated to be R=0.9824 with (p<0.001) suggesting a statistically significant agreement.

Keywords

• Helmholtz Coil
• Magnetic Field
• Spin Exchange Optical Pumping

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