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We carried out the three-dimensional (3-D) mechanical design of a 2-m-long 20 T common-coil dipole magnet and provided solutions for coil stress management. Instead of using flared ends to make space for the beam pipe, the prototype magnet is designed with a coil configuration which consists of four Nb3Sn and six Bi-2212 flat racetrack coils. The designed peak coil field is 20.4 T at the operating current of 14 700 A. The operating margin is 11% on the load line at 4.2 K. The magnitude of the calculated Lorentz force for 1/8 model is around 1562, 405, and 206 t for the horizontal, vertical, and axial directions, respectively. The special coil configuration and such significant magnetic force bring unprecedented challenges in applying preload to coils and optimizing the coil stress and the stress in the other components. By using an extended aluminum shell and a split yoke assembly, we minimized the coil end effects and applied a uniform and large enough preload to the coil straight section and the coil ends. This paper presents the stress analysis and the optimized 3-D mechanical design of the magnet. [ABSTRACT FROM AUTHOR]

This paper presents the shrink-fit multilayered aluminum shell (SMAS) used for withstanding large Lorentz force in a 20-T shell-based common-coil accelerator dipole magnet. Finite element analysis (FEA) is carried out to optimize the required shell thickness when a single layer aluminum shell is used to support the 20-T dipole magnet. Also, FEA is carried out to study the performance of a three-layer SMAS used in the same dipole magnet. The analyzed results indicate that the three-layer SMAS with thickness of 75 mm can help us to reduce the peak shell stress significantly compared to a 75-mm-thick single layer aluminum shell when they provide the same preload to the coils. Some preliminary experiments have been carried out which prove that the initial stress distribution in the SMAS can be well controlled after the assembly. Hopefully, the outer diameter of the twin-aperture 20-T common-coil dipole magnet can be restricted to 900 mm if we use a three-layer SMAS as the support structure. [ABSTRACT FROM AUTHOR]

Presents a study that assessed cylindrical permanent-magnet structures that exploit the image effect in a surrounding circular soft-iron sheath. Introduction of a theory of sheathed infinite length cylindrical multipole magnet structures using the idea of magnetic images in the surrounding iron; Observations on the changes in multipole field when surrounded by a sheath; Description of the construction and performance of a small dipole ring magnet.