A 30-Centimeter Bore, 70-Kilogauss Superconducting Helmholtz Magnet
This paper summarizes the design, procurement and testing of a 30-cm Heimholte coil with a central field of 70 kG. In 1966, it was decided to build a large-scale supermagnet which could be used for high-energy physics experiments, as well as to be utilized as a general purpose magnet to study high-field properties of new Type-II superconductors, heat transfer, thermal conductivity, etc. The coils have an outer diameter of 90 cm and a total axial length of 66 cm with an axial gap of 8 cm. To utilize the full capability of the magnet, each coil half is subdivided into three modules which may be energized from one or separate current sources. When the inner coil alone is energized, the central field of 30 kG in stable mode is obtained; however, this section can be operated up to 35 kG without quench. The field homogeneity in the center is measured to be ΔB/B = 7 × 10-4 inside a 2.0-cm diameter sphere and can be im? proved by adding higher-order solenoids inside the bore to achieve a field homogeneity value of ΔB/B = 10-5 or 0.7 G.
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