Magnet Quench Research Articles

Power deposition in the He bath induced by the Z gradient coil in the 11.7 T Iseult magnet: theory versus measurements

Gradient-magnet interactions increase with higher field magnets and stronger gradient coils. Perhaps the most sensitive aspect is magnet quench, which can be induced by a loss of superconductivity of the main coil caused by a rise of the temperature of the He bath with gradient activity. Predicting power depositions thereby can be a very valuable tool to avoid dangerous frequency zones but also eventually correct design flaws. In this work, we report model predictions compared to measurements of power deposition in the He bath of the Iseult 11.7 T magnet for the Z gradient coil axis.

Cryogenic and safety design of the future high field cable test facility at Fermilab

The HFVMTF (High Field Vertical Magnet Test Facility) is a new experimental facility under development at Fermi National Accelerator Laboratory (FNAL) to test large superconducting magnets (up to 20 tons weight and 1.3 m diameter) in a double bath superfluid helium cryostat (1.9 K and 1.2 bar). Coupled with a superconducting dipole magnet fabricated by Lawrence Berkeley National Laboratory (LBNL), this facility will be able to test future high-temperature superconductor (HTS) cables under a background magnetic field of 15 T for fusion magnets. This paper describes the design of the cryostat and its 1.4-meter diameter lambda plate, as well as the different components for a safe operation of the facility, even during critical events such a magnet quench or a vacuum breaking situation. The project is funded by US DOE Offices of Science, High Energy Physics (HEP), and Fusion Energy Sciences (FES).

First results of the cryogenics operation from the LHC physics Run 3 at the increased energy to 6.8 TeV

Back in 2018, LHC completed its Run 2 physics period. Consolidation, maintenance, and upgrade activities performed during the subsequent Long Shutdown 2 period (LS2), based on a data-driven approach, allowed for full potential availability of the LHC cryogenics infrastructure before tackling the 2021 magnet quench training campaign, preparing the whole machine for operation at the increased energy of 6.8 TeV. This paper will first give a summary of the main upgrades, consolidations and maintenance performed during the LS2. Magnet training of the machine to the increased energy of 6.8 TeV will be addressed. Results of the first year (2022) of Run 3 physics will be presented, achieving high cryogenic availability in a heavily sustained operational context of the accelerator (beams energy increase, induced heat load, peak & integrated luminosity). Helium inventory management aspects will be discussed, with a particular highlight on the necessary operational adjustments taken to cope with the present supply market evolution. Implementation of several operational modes for cryogenic plants will be presented, towards significant electrical power savings while maintaining nominal physics production at the highest availability rate.

Continuous Fiber Bragg Grating Optical Sensors for Superconducting Magnet Quench Detection: The Effects of Attenuation and Position in the Array

Quasi-continuous arrays of fiber Bragg gratings (FBGs) show great promise for quench protection in superconductors. The number of identical gratings and the reflectivity of the individual gratings are important parameters determining the sensitivity of the system to a local temperature or strain perturbation. We apply strain to shift the Bragg wavelength of a single FBG through the spectrum of an array of up to 1000 identical gratings, and map out the detection sensitivity for a given <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex-math notation="LaTeX">$\Delta \lambda$</tex-math></inline-formula> relative to the peak reflectance of the FBG array, and show that the position of the perturbed FBG matters only due to the broadband attenuation of the probe light down the array. Varying the number of gratings in the array shows the interplay between the number of gratings, the reflectivity of the gratings, and the sensitivity of the system. We demonstrate that the ability to model the spectrum of the FBG array is crucial to predicting system performance.

Advances in Searching for Galactic Axions with a Dielectric Haloscope (MADMAX)

AbstractAxions are hypothetical particles that could explain the observed dark matter density and, simultaneously, could naturally resolve the strong charge parity (CP) problem in quantum chromodynamics (QCD). Recent theoretical works indicate that axions are expected to have masses in the range of , a range that presently still evades experimental detection. An experimental design is presented to search for QCD axions in this mass range via the magnetized disk and mirror axion experiment (MADMAX). MADMAX will be composed of multiple movable dielectric disks and a stable mirror that are placed inside a strong magnetic field to utilize the axion‐induced coherent electromagnetic wave emissions from each disk surface. In this paper, new R&amp;D milestones achieved will be reported, that is, the updated magnet quench protection system, a closed booster dielectric haloscope system tested in the MORPURGO magnet at (European Organization for Nuclear Research) CERN using a full experimental data acquisition chain. These new main novel accomplishments investigate the feasibility of the experiment.

Measurement of zero-zone voltage for vacuum circuit breaker with oscillation zero-crossing circuit

Vacuum Circuit Breaker (VCB) with oscillation zero-crossing circuit is wildly used to interrupt high direct current, especially in the magnet quench protection system. The injection time of reverse current is the critical factor that affect the breaking result. During the current breaking period, the voltage of VCB varies in a wide range, while the arc voltage in zero-zone is very small and changes rapidly. Therefore, the conventional methods cannot meet the voltage measurement requirements. In this paper, a bi-directional zero-zone voltage measurement scheme for VCB was proposed. According to the variation characteristics of transient voltage during the breaking process, the design and simulation verification of the measurement device were completed. Then the high voltage impulse experiment and arcing measurement testing were carried out by the developed prototype of the arc voltage measurement device. The experimental results indicated that the device has fast response and high measurement accuracy, which meets the measurement requirements of VCB zero-zone voltage.

Superconducting Magnet Design for a Vertical-Ring High Gradient Magnetic Separation System

This paper describes a design of a Vertical-ring High Gradient Superconducting Magnetic Separation (VHGMS) system for recovery of the magnetic ore and purification of non-metallic minerals. Compared to the conventional design which uses copper wires, using superconducting magnet can help reduce the energy consumption and increase the magnetic field. The first part of this paper introduces the operation margin design of the superconducting magnet. This magnet is wound with NbTi wires and its temperature margin is designed to be higher than 1 K. It generates an average magnetic field above 2 T in the filtering area. The second part of this paper introduces a quench protection circuit implemented in this magnet and post-quench analysis is also presented. Simulation results show that maximum temperature and terminal voltage are within the safe limits. So, the superconducting magnet can be effectively protected from burning-out during a quench. The third part of this paper proposes a novel reinforcement structure for the coil and analyzes the stress status during magnet charging and quench process. The Von mises stresses in the coil and stainless steel are both in allowable stress region and have a large safety margin.

Test Result of a Full-Scale Prototype of Beam Separation Dipole Magnet for the High-Luminosity LHC Upgrade

High Energy Accelerator Research Organization (KEK) is developing Nb-Ti based beam separation dipole (MBXF) for the high-luminosity Large Hadron Collider (HL-LHC) upgrade within the framework of CERN&#x2013;KEK collaboration. This magnet produces field integral of 35 T&#x2022;m in a 150 mm bore at 12 kA and 1.9 K. KEK has fabricated and tested three 2 m-long model magnets as in-house activities. After the technologies cultivated in these model magnet development was transferred from KEK to a manufacture, construction of the first full-scale prototype (MBXFP1) started in Hitachi. This paper reports test result of cold test for MBXFP1 including training, mechanical behavior, magnetic field quality and quench protection.

Design of a Curved Superconducting Combined Function Bending Magnet Demonstrator for Hadron Therapy

Curved superconducting bending magnets have clear potential for compact hadron therapy gantries and medical synchrotrons. A combined function superconducting bending magnet design based on collared cos-theta coils is proposed for a new compact and cost-effective hadron therapy gantry initiative. This 3 T magnet, based on the technologies extensively developed for the LHC project, includes several gantry-specific features that shall be developed and validated with a demonstrator magnet. The main development areas include fabrication of epoxy-impregnated cos-theta Nb-Ti coils with 2.2 m radius of curvature along with the assembly of the surrounding curved cold mass. This paper presents the magnetic and mechanical design optimization of the proposed demonstrator magnet, the results of the numerical modelling of the transient losses during operation as well as the magnet quench protection analysis.

Dipole Magnets Wound Using YBCO Cables-FEM Stability Issues Modeling

Quench and protection in magnets wound with coated conductors is of great interest for many applications, including high energy particle accelerators. The relatively large slow normal zone propagation and large MQE of coated conductors and the potential of burn out in well insulated coils has led to an interest in non-insulation coils. A stability of block type dipole magnets wound using non-insulated YBCO Roebel and CORC cables has been modeled by FEM. Critical currents of the magnets have been calculated using a self-consistent method based on anisotropic I_c(B) curves of the cables. Advantages and disadvantages of using the Roebel and CORC cables in dipole magnet windings have been discussed. Measured heat disturbances of different size, intensity and duration in a pancake coil wound using a non-insulated YBCO tape have been analyzed from the viewpoint of the magnet quench and stability. The effect of CORC cable magnetization on the field quality of a canted cosine theta dipole was evaluated.

Nonlinear current and dynamical quantum phase transitions in the flux-quenched Su-Schrieffer-Heeger model

We investigate the dynamical effects of a magnetic flux quench in the Su-Schrieffer-Heeger model in a one-dimensional ring geometry. We show that, even when the system is initially in the half-filled insulating state, the flux quench induces a time-dependent current that eventually reaches a finite stationary value. Such persistent current, which exists also in the thermodynamic limit, cannot be captured by the linear response theory and is the hallmark of nonlinear dynamical effects occurring in the presence of dimerization. Moreover, we show that, for a range of values of dimerization strength and initial flux, the system exhibits dynamical quantum phase transitions, despite the quench is performed within the same topological class of the model.

Study on reducing the impact to EAST cryogenic system caused by the failure of load devices

EAST tokamak has complicated supercritical helium loops for cooling the superconducting magnets and other thermal loads. When failures occur in these load devices, such as magnet quench or vacuum failure, a large amount of helium evaporated in the cryogenic circuits returns to the cryogenic distribution system, which makes the pressures rise and the helium returning to the refrigerator increases. The refrigerator will run in a supercooling state and the turbine protection shutdown will be triggered with probability, which further affects the operation of the cryogenic system. This paper analyzes the archive data of this undesired phenomenon, the EAST cryogenic system model based on EcosimPro is used to simulate the dynamic process during the failure. A split-range control scheme to stabilize the pressures in the distribution system under failure state is proposed. the control module is developed in EcosimPro, simulation results show that it could achieve a satisfactory control performance and reduce the impact caused by the failure.

Holographic Abrikosov lattice: Vortex matter from black hole

The $\mathrm{AdS}/\mathrm{CFT}$ correspondence provides a unique way to study the vortex matter phases in superconductors. We solve the dynamical evolution of a superconductor in $2+1$ dimensions at a finite temperature subjected to a magnetic field quench in terms of a gravitational ``hairy black hole'' dual living in an asymptotic ${\mathrm{AdS}}_{4}$ space. We exploit this to determine the nature of the equilibrium states realized at long times after the quench of this two dimensional type II superconductor in a perpendicular external uniform magnetic field ${B}_{0}$. This holographic superconductor exhibits the generic lower (${B}_{c1}(T)$) and upper (${B}_{c2}(T)$) critical fields. For ${B}_{0}&lt;{B}_{c1}(T)$ the magnetic field is completely expelled revealing the Meissner phase, while the superconductivity is destroyed when ${B}_{0}&gt;{B}_{c2}(T)$. Abrikosov lattices appear in the range ${B}_{c1}(T)&lt;{B}_{0}&lt;{B}_{c2}(T)$ that realize various configurations in the form of hexagonal, square and slightly irregular square lattices pending the magnetic field strength and the influence of finite size boundaries. We show this to be consistent with the expectations of Ginzburg-Landau theory where the upper and lower critical fields are associated with the inverse squares of the coherence length and magnetic penetration depth, respectively.

Bond Graph as a Tool for Modelling Superconducting Magnet Quench

Bond Graph as a Tool for Modelling Superconducting Magnet Quench

Magnet Quench Factors in Ramping-up Procedure

Ramping-up is the magnet current injection procedure which is under the control of resistance, voltage, current lead temperature, magnet pressure, temperature and so on. In this procedure, the factors related to the stability of the magnet such as, magnet temperature, pressure and currents are constantly changing. This procedure is the main step which the magnet-quench occurs in. This study uses the data collected during 7 years and SIMENS MRI ramping-up theory, in order to help engineers understand the key factors to reduce the magnet quench during the ramping up procedure.

Exploring New Resin Systems for Nb3Sn Accelerator Magnets

Epoxy resins have long been a focus of magnet design. They provide strength and stability to the superconductor, to allow coil fabrication and consistent magnet performance. They are often cited as a main contributor to magnet performance, often as a limiting factor, from epoxy cracking and energy release. New resin systems are being designed to improve magnet quench and training performance through several means. Baseline candidate resin systems are evaluated for neat resin mechanical properties as well as behavior in Nb <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sub> Sn subscale composites. This data feeds additional resin system tuning to meet the goals stated above.

1.5 T Nuclear Magnetic Resonance Imaging System Failure Treatment and Rectification Summary

Quench of magnetic resonance imaging system refers to the process that the superconducting condition inside the magnet is destroyed due to some reason. The large current stored in the coil is quickly converted into heat at the place where the resistance is formed, and a large amount of liquid helium in the magnet is evaporated. If it happens, it will cause huge loss to the user. We introduce the real cases of 1.5 T magnetic resonance imaging system's quench fault, maintenance treatment and management improvement, which can be used for reference by various medical institutions, so as to better strengthen the operation and maintenance management of magnetic resonance imaging system, so as to avoid the occurrence of out of tolerance fault, and do a good job in the guarantee work after the out of tolerance fault.

A High-Efficiency Protecting Scheme for HTS Inserts in Case of Background Magnet Quenches

For extremely high field magnets, the LTS/HTS structure is an efficient and economical solution. In an LTS/HTS magnet system, the LTS (Low-temperature superconducting) background field magnet is deeply mutual inductance coupled with the HTS (High-temperature superconducting) insert magnet. A sudden background LTS magnet quench may potentially destroy the double pancakes (DPs) of the insert HTS magnet because of the induced current and the resulting additional electromagnetic stress. To improve the safety and stability of the LTS/HTS magnet system, this article proposed a new passive protecting scheme of the LTS/HTS system. In this scheme, a magnetic dam is arranged between the insert magnet and the background field magnet. When the background field magnet quenches, the magnetic dam can help to slow down the magnetic flux variation in the insert magnet. According to the simulation results, a magnetic dam can significantly reduce the instantaneous stress rise of the insert magnet by 65.3protective effect of the magnetic dam was also verified by the experiments with a Bi-2223 insulating coil magnet. The structural parameters affecting the isolating effect of the magnetic dam were also discussed. Based on these work, researchers can further improve the safety and stability of the LTS/HTS magnet system.

Impact of betatron collimation losses in the High-Energy Large Hadron Collider

In response to recommendations in the 2013 update of the European Strategy for Particle Physics, a conceptual design effort for an energy upgrade of the Large Hadron Collider (LHC) at CERN, the so-called high-energy LHC (HE-LHC), was launched as part of the Future Circular Collider study. The HE-LHC machine, which is meant to use 16 T magnet technologies in the existing LHC tunnel, would provide proton collisions at a center-of-mass energy of 27 TeV ($\ensuremath{\sim}2\ifmmode\times\else\texttimes\fi{}\mathrm{LHC}$) with a total stored energy of 1.34 GJ ($\ensuremath{\sim}4\ifmmode\times\else\texttimes\fi{}\mathrm{LHC}$) per beam. By adapting the LHC collimation system, a first layout of the HE-LHC's betatron cleaning insertion was conceived, with the requirement to sustain---for at least 10 seconds---the impact of about 1.86 MW, corresponding to a beam lifetime of 12 minutes, without inducing any magnet quench nor any damage to other accelerator components. In this article, we evaluate the power deposition on the collimation insertion for proton beam operation in the HE-LHC machine at top energy, by means of particle tracking and interaction calculations. The beam loss effects on the warm elements as well as on the superconducting dispersion suppressor magnets are assessed through a three-step simulation approach. In particular, for the proposed future high-energy LHC, we demonstrate the necessity of adding local collimators in the dispersion suppressor, and we uncover the harmful consequences of a potential removal of the beam line ``dogleg'' in the collimation insertion.

Mechanical Behavior of the Shielded HL-LHC Beam Screen During a Magnet Quench

In the framework of the High-Luminosity Large Hadron Collider (HL-LHC) project, larger and shielded beam screens will be installed in the beam pipe of the superconducting magnets of the insertion next to the ATLAS and CMS detectors. The beam screen is a complex assembly that guarantees the vacuum requirements while shielding the magnet cold mass from the induced heat loads. Such an assembly has to withstand high intensity electromagnetic forces induced during magnet quenches. The mechanical stability was verified in a dedicated quench test campaign performed at the magnet test station of CERN. Strain gauges, custom-made probes, and optical fibers were installed in the beam screen to measure deformations during a quench. Magnetic field measurements were also carried out by means of pick-up coils mounted within the assembly. The main outcomes of this work are the elastic behaviour of the beam screen after 52 quenches and a satisfactory agreement between measurements and simulations.