High-Field Superconducting Magnets

Liebel, H

doi:10.1007/174_2010_100

Cited by 7 publications

(7 citation statements)

References 27 publications

(43 reference statements)

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“…A benchmark instantaneous scanning bandwidth of ∼50 MHz, where the quality factor Q ∼ 10 4 needed to reach QCD axion sensitivity is tenable in practice for about four dozen layers made of zirconia, is compatible with our experimental results [71]. The experiment cryostat is housed within the bore of a regular superconducting magnet [68]. Microwaves arise in an axion-photon-photon vertex.…”

Section: Introductionsupporting

confidence: 68%

“…0 , with T sys being the system temperature, A the cross-sectional area, Q the quality factor, t the integration time-typically t ≲ 1 ms per subspectrum to mitigate 1/f noise, which are stacked into a single spectrum at each frequency to mitigate white noise [74]-and B 0 the magnetic field strength. Therefore, in addition to procuring a powerful superconducting solenoid with a large bore that allows for housing a lowtemperature cryostat with a large cross-sectional area-e.g., [68]-it becomes crucial to provide a high Q factor. The quality factor of a Fabry-Pérot resonator, defined as 2π times the ratio of the energy stored in the resonator and the energy loss per oscillation period, is Q = ωτ g , where the group delay time, τ g , is the average lifetime of a photon in the resonator or, equivalently, decay time of the energy density of radiation in the interferometer, and adopts typical values of a few nanoseconds per layer [75].…”

Section: Introductionmentioning

confidence: 99%

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A Forecast of the Sensitivity of the DALI Experiment to Galactic Axion Dark Matter

Hernández-Cabrera,

De Miguel,

Joven Álvarez

et al. 2024

Symmetry

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The axion is a long-postulated boson that can simultaneously solve two fundamental problems of modern physics: the charge–parity symmetry problem in the strong interaction and the enigma of dark matter. In this work, we estimate, by means of Monte Carlo simulations, the sensitivity of the Dark-photons & Axion-Like particles Interferometer (DALI), a new-generation Fabry–Pérot haloscope proposed to probe axion dark matter in the 25–250 μeV band.

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Section: Introductionsupporting

confidence: 68%

Section: Introductionmentioning

confidence: 99%

A Forecast of the Sensitivity of the DALI Experiment to Galactic Axion Dark Matter

Hernández-Cabrera,

De Miguel,

Joven Álvarez

et al. 2024

Symmetry

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“…Historically the preferred design for UHF is a compensated solenoid because the peak fields in the conductors are only slightly higher than the field generated in the bore [10]. In this case the majority of the field is generated by a simple long solenoid that stretches the entire length of the magnet.…”

Section: Designmentioning

confidence: 99%

Ultra-high field magnets for whole-body MRI

Warner

2016

Supercond. Sci. Technol.

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For whole-body MRI, an ultra-high field (UHF) magnet is currently defined as a system operating at 7 T or above. Over 70 UHF magnets have been built, all with the same technical approach originally developed by Magnex Scientific Ltd. The preferred coil configuration is a compensated solenoid. In this case, the majority of the field is generated by a simple long solenoid that stretches the entire length of the magnet. Additional coils are wound on a separate former outside the main windings with the purpose of balancing the homogeneity. Most of the magnets currently in operation are passively shielded systems where the magnet is surrounded by a steel box of 200–870 tonnes of carbon steel. More recently actively shielded magnets have been built for operation at 7 T; in this case the stray field is controlled by with reverse turns wound on a separate former outside the primary coils. Protection against quench damage is much more complex with an actively shielded magnet design due to the requirement to prevent the stray field from increasing during a quench. In the case of the 7 T 900 magnet this controlled by combining some of the screening coils into each section of the protection circuit. Correction of the field variations caused by manufacturing tolerances and environmental effects are made with a combination of superconducting shims and passive shims. Modern UHF magnets operate in zero boil-off mode with the use of cryocoolers with cooling capacity at 4.2 K. Although there are no cryogen costs associated with normal operation UHF magnets require a significant volume (10 000–20 000 l) of liquid helium for the cool-down. Liquid helium is expensive therefore new methods of cool-down using high-power cryocoolers are being implemented to reduce the requirement.

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“…A small-scale experiment of this passive protection system has been reported [17]. Several reliable options for quench protection of MRI magnets are known for MRI [18,19] and 400 M nuclear magnetic resonance (NMR) [20]. Moreover, the quench propagation kinetics of the whole body 11.7 T MRI magnet shielding coils were also investigated [21].…”

Section: Introductionmentioning

confidence: 99%

Systematic analysis of the quench process performance and simulation of the 9.4 T-800 mm whole-body MRI magnet

Chen

Wang

Zhang

et al. 2023

Supercond. Sci. Technol.

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In 2021, the Institute of Electrical Engineering, Chinese Academy of Sciences successfully reached 9.4T in a whole-body magnetic resonance imaging (MRI) superconducting magnet with an inner diameter of 800 mm. In this study, a systematic analysis of both the real quench protection performance and a simulation are reported. The four successful quench protections during the entire energization process proved the feasibility of the “in-out-in” quench protection protocol for a 9.4T-800 mm superconducting magnet. The quench trigger sequence was shown to be adjusted by changing the heater thickness, which demonstrates the flexibility of the “in-out-in” quench protection protocol to fit a different MRI magnet design. The high accuracy of the quench protection simulation method and code was confirmed through comparison of the simulation results with the real performance. Moreover, the limitations of the current quench protection and reference value to other MRI magnets were discussed. It is believed that this study will be useful to other research groups and promote the development of an extremely high-field whole-body MRI system.

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High-Field Superconducting Magnets

Cited by 7 publications

References 27 publications

A Forecast of the Sensitivity of the DALI Experiment to Galactic Axion Dark Matter

A Forecast of the Sensitivity of the DALI Experiment to Galactic Axion Dark Matter

Ultra-high field magnets for whole-body MRI

Systematic analysis of the quench process performance and simulation of the 9.4 T-800 mm whole-body MRI magnet

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