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At least 109 records · Page 6

Magneto-Mechanical Optimization of Cross-Sections for $ \text{cos}(\theta)$Accelerator Magnets

The cross-section design of cos (θ) superconducting magnets is historically developed in a two-step process: initially, the coil geometry is defined on the basis of magnetic optimizations; then, the structure is designed around the coil. The first step searches for the best coil cross-section maximizing the magnetic field, margin, field quality and conductor efficiency. The latter step aims at limiting the coil stresses and deformations. However, the coil design, defined with the initial magnetic optimization, can influence the mechanical behaviour of the magnet, altering, for example, the peak stress during operation. As the critical current is a function of the applied strain, the mechanical implications of the coil cross-section design can limit the achievable performance. In this paper we propose an integrated optimization process that targets the peak stress on the conductor in addition to the magnetic objectives. Here the results are presented for a sample high-field Nb 3 Sn dipole: a 4-layer design aiming at ultimate conductor performance.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

A Flexible Field Mapping System for Accelerator Magnets

Magnetic field mapping is a fundamental magnetic measurement method that typically uses Hall and NMR sensors. In magnet measurement facilities, such systems are likely used in various configurations suitable for a specific task at hand. To address this diversity, the authors developed a flexible field mapping system capable of being configured and tailored to each particular measurement case. Further, the system needs to address the variability introduced by differences in sensors and their readout systems, probe positioning systems, power supply systems, and required mapping geometry (mapping space and grid, measurement steps and sequences). Although the discussed field mapping systems range from a self-propelled multi-sensor mapper of a large detector magnet to a single 3D Hall sensor system to scan a small permanent magnet, they were all built with the same core mapping system. The variability present in field mapping systems, the measurement system architecture addressing this variability, as well as examples of several field mapping systems built in this architecture are presented.

75 CONDENSED MATTER PHYSICS, SUPERCONDUCTIVITY AND↗

A Hybrid HTS/LTS Superconductor Design for High-Field Accelerator Magnets (Final Report)

This paper presents the design, construction, and test results of a hybrid dipole magnet. The inner coils were of second generation (2G) high-temperature superconductor (HTS) ReBCO tape and the outer coils were of low-temperature superconductor (LTS) Nb 3 Sn Rutherford cable. The HTS and LTS coils were independently powered and protected using different power supplies. The HTS coils were quenched many times with no degradation in performance observed. The hybrid field reached ~8.6 T, which is believed to be a record for a hybrid dipole. The maximum field was limited by the stable operation of the leads in the LTS coil at 8000 A. The HTS coils were independently ramped to 800 A, and the LTS coils to 10,000 A. With improved leads and instrumentation, this hybrid dipole is expected to produce over 13 T when the ReBCO tape in the HTS coil is aligned nearly parallel to the field. One major purpose of this program was to perform magnetization studies in the coils made with the HTS tape. Magnetization-induced field errors are expected to be small when the field is nearly parallel to the wide face of the tape. The magnetization measurements were performed at 77 K with the two racetrack coils in two orientations, with field predominantly either parallel or perpendicular to the wide face of the HTS tape. In addition, measurements were also performed at 4 K in different background fields provided by the outer Nb3Sn coils. This paper will summarize the magnetization measurements and present the quenching experience of the HTS coils in this hybrid magnet system.

99 GENERAL AND MISCELLANEOUS↗

Superconducting Magnets for Accelerators

Superconducting magnets have enabled great progress and multiple fundamental discoveries in the field of high-energy physics. This chapter reviews the use of superconducting magnets in particle accelerators, introduces Nb$_{3}$Sn superconducting accelerator magnets, and describes their main challenges.

43 PARTICLE ACCELERATORS↗

FIRST-ORDER PARTICLE ACCELERATION IN MAGNETICALLY DRIVEN FLOWS

We demonstrate that particles are regularly accelerated while experiencing curvature drift in flows driven by magnetic tension. Some examples of such flows include spontaneous turbulent reconnection and decaying magnetohydrodynamic turbulence, where a magnetic field relaxes to a lower-energy configuration and transfers part of its energy to kinetic motions of the fluid. We show that this energy transfer, which normally causes turbulent cascade and heating of the fluid, also results in a first-order acceleration of non-thermal particles. Since it is generic, this acceleration mechanism is likely to play a role in the production of non-thermal particle distribution in magnetically dominant environments such as the solar chromosphere, pulsar magnetospheres, jets from supermassive black holes, and γ-ray bursts.

79 ASTRONOMY AND ASTROPHYSICS↗