As part of the US Magnet Development Program, Lawrence Berkeley National Laboratory (LBNL) is working on the development of high field stress-managed Nb<inline-formula><tex-math ...notation="LaTeX">_{3}</tex-math></inline-formula>Sn dipole magnets using canted-cosine-theta (CCT) technology. As part of this program, a series of two layer magnets, CCT3/4/5, with short sample bore field of approximately 10 T and a 90 mm diameter open aperture have been designed, fabricated, and tested. The first magnet in the series, CCT3, was limited to less than 70% of the short sample current, this limitation is believed to be due to conductor damage. The second magnet in the series, CCT4, reached 86% of the short sample current, after changes to the groove geometry were made to accommodate dimensional changes in the cable during heat treatment. The third and final magnet of this series, CCT5, reached 88% of the short sample current with improved training relative to CCT4, after changes were made to the impregnation and assembly methods. While this two layer series was used to successfully demonstrate Nb<inline-formula><tex-math notation="LaTeX">_{3}</tex-math></inline-formula>Sn CCT magnet technology, improvements in the training behavior of these magnets is desirable. For this purpose, a subscale program has been devised in order to probe the causes and explore reductions / improvements to training in stress-managed magnet technology. The subscale nature of the magnets allows for faster turnaround in the fabrication and testing process. In this paper, we present the design and test results for the first (baseline) subscale Nb<inline-formula><tex-math notation="LaTeX">_{3}</tex-math></inline-formula>Sn CCT magnet and demonstrate that the subscale platform and the larger two-layer magnets produce similar training results.
Recent studies have shown that strong, alternating focusing magnets can be used to greatly increase the momentum acceptance of hadron therapy gantries. With the high gradients achievable with ...superconducting magnets a level of momentum acceptance can be reached which may have significant implications to medical gantries and to the introduction of superconducting technology in this area. The design of such a superconducting magnet system for a proton therapy gantry will be presented. The Canted-Cosine-Theta concept is extended to a curved magnet system generating the desired bending and alternating focusing fields for the achromatic optics. Magnetic, structural, and thermal analysis of this design is presented along with preliminary efforts towards fabrication and assembly of the curved magnet.
Worldwide several electron cyclotron resonance (ECR) ion sources have been developed and in operation for heavy ion accelerators using Nb-Ti superconducting magnets. The Versatile ECR ion source for ...NUclear Science (VENUS) at the Lawrence Berkeley National Lab (LBNL) and the newly commissioned 28 GHz superconducting ECR ion source at the Facility for Rare Isotope Beams (FRIB) were developed by LBNL. Both sources adopt a scheme with a sextupole magnet inside a mirror-type solenoid to confine the ions and electrons. Nb-Ti coils limit all the existing ECR ion sources to operate below <inline-formula><tex-math notation="LaTeX">\sim</tex-math></inline-formula>9 T at 4.2 K. Nb<inline-formula><tex-math notation="LaTeX">_{{\text{3}}}</tex-math></inline-formula>Sn potentially enables next generation ECR ion sources with a higher field limit (<inline-formula><tex-math notation="LaTeX">\sim</tex-math></inline-formula>22 T at 4.2 K). As an example, a 45 GHz ECR ion source Nb<inline-formula><tex-math notation="LaTeX">_{{\text{3}}}</tex-math></inline-formula>Sn magnet is currently being developed by the Institute of Modern Physics (IMP) in China. Clearly conductor characteristics of Nb<inline-formula><tex-math notation="LaTeX">_{{\text{3}}}</tex-math></inline-formula>Sn are very much different and new development are needed to meet challenges such as coil fabrication. FRIB and LBNL team up again to develop ECR ion sources based on Nb<inline-formula><tex-math notation="LaTeX">_{{\text{3}}}</tex-math></inline-formula>Sn. Here as the first step, this paper describes the design of a second 28 GHz superconducting ECR ion source using Nb<inline-formula><tex-math notation="LaTeX">_{{\text{3}}}</tex-math></inline-formula>Sn coils at FRIB. We present conductor selection and characteristics, magnetic design, mechanical design and cold mass assembly, coil fabrication challenges and potential solution, quench protection, and the development and prototyping efforts so far.
The superconducting electron cyclotron resonance (ECR) source magnet for the facility for rare isotope beams at Michigan State University was designed and built by the Superconducting Magnet Group at ...Lawrence Berkeley National Laboratory (LBNL) in 2017. The 28 GHz NbTi ion source magnet features a sextupole-in-solenoids configuration which is comparable to the VENUS ECR magnet operated at LBNL. However, the mechanical design of this magnet utilizes a shell-based support structure which allows fine adjustments to the sextupole preload and reversibility of the magnet assembly process. The magnet has been assembled and tested to operational currents at LBNL. This paper describes the mechanical analyses performed to estimate the sextupole's and solenoids' preloads. We will report on the 3-D finite element analysis during room temperature assembly, cool-down, and magnet excitation, and then describe the magnet preload operations. Finally, we will describe the performance of the support structure during the quench training.
The Nb<inline-formula><tex-math notation="LaTeX">_{3}</tex-math></inline-formula>Sn based test facility dipole magnet (TFD), with a rectangular aperture of 100 × 150 mm, and an operation target bore ...field of 15 T at 1.9 K, is designed to provide a background dipole field for cables and inserts. The design of the magnet is based on four double-layer coils and an aluminum shell-based structure, using key-and-bladder technology, with axial pre-load. The status of the magnet design, and optimization analyses, are here presented. The results of the initial prototyping, initial winding tests, characterization of cable hard-way bend curvature, and layer jump prototype test are also discussed.
Canted-Cosine-Theta (CCT) magnet is an accelerator magnet that superposes fields of nested and tilted solenoids that are oppositely canted. The current distribution of any canted layer generates a ...pure harmonic field as well as a solenoid field that can be cancelled with a similar but oppositely canted layer. The concept places windings within mandrel's ribs and spars that simultaneously intercept and guide Lorentz forces of each turn to prevent stress accumulation. With respect to other designs, the need for pre-stress in this concept is reduced by an order of magnitude making it highly compatible with the use of strain sensitive superconductors such as Nb 3 Sn or HTS. Intercepting large Lorentz forces is of particular interest in magnets with large bores and high field accelerator magnets like the one foreseen in the future high energy upgrade of the LHC. This paper describes the CCT concept and reports on the construction of CCT1 a "proof of principle" dipole.
A two-layer subscale canted-cosine-theta 4.5 T has been built and successfully tested. The design of the magnet is based on Nb 3 Sn cable wound into aluminum bronze mandrels, and an external aluminum ...shell. The magnet was conceived as an agile platform for the development of canted-cosine-theta magnets and general magnet technology. The main fabrication, assembly and analysis processes developed for this magnet are discussed in detail. The training behavior and mechanical response of magnet's structure in relation to previous canted-cosine-theta magnets are also discussed.
Test Results of the LARP Nb3Sn Quadrupole HQ03a DiMarco, J.; Ambrosio, G.; Anerella, M. ...
IEEE transactions on applied superconductivity,
06/2016, Letnik:
26, Številka:
4
Journal Article
Recenzirano
Odprti dostop
The U.S. LHC Accelerator Research Program (LARP) has been developing Nb 3 Sn quadrupoles of increasing performance for the high-luminosity upgrade of the large hadron collider. The 120-mm aperture ...high-field quadrupole (HQ) models are the last step in the R&D phase supporting the development of the new IR Quadrupoles (MQXF). Three series of HQ coils were fabricated and assembled in a shell-based support structure, progressively optimizing the design and fabrication process. The final set of coils consistently applied the optimized design solutions and was assembled in the HQ03a model. This paper reports a summary of the HQ03a test results, including training, mechanical performance, field quality, and quench studies.
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