Solenoid Magnet Research Articles

A Custom Finite-Element Method Framework for Designing Superconducting Solenoidal Magnets and Coils With True HTS Tape Geometry

A Custom Finite-Element Method Framework for Designing Superconducting Solenoidal Magnets and Coils With True HTS Tape Geometry

A new fast and robust thermo-hydraulic code for ITER superconducting magnet simulation

A new software is being developed for plasma pulse scenario validation of the ITER magnet system behaviour and prediction of the margin to quench in superconductors. The principal idea behind this project has been to develop a software tool for the thermo-hydraulic simulation of superconducting magnets that is able to simulate different operations scenarios for the magnets at least an order of magnitude faster than real time. To achieve this level of performance, a tight coupling between the Cable-In-Conduit-Conductors and the structure of the magnet is performed. All the equations for the flow and heat conduction parts of the global model are put in a single sparse system that is integrated in time. Such tight coupling in combination with implicit time stepping allows much longer time steps whilst keeping high accuracy of the solution. The code named REIMS (Riemann Explicit Implicit Magnet Simulator) is still under development. Both central solenoid (CS) and toroidal field (TF) ITER magnets are available at this stage. The development of the different intermediate steps that led to the current version of the code required verification/validation against exact solutions, experimental data and/or comparisons with existing codes. In the same way, results obtained with REIMS for the simulation of both CS and TF loops after application of a short plasma pulse scenario have been compared to results from existing reference codes, showing a good agreement.

Design and analysis of a HTS internally cooled cable for the Muon Collider target and capture solenoid magnets

The Muon Collider is one of the options considered as the next step in High Energy Physics. It bears many challenges, last not least in superconducting magnet technology. The target and capture solenoid is one of them, a channel of approximately 18 m length consisting of co-axial solenoid magnets with a 1.2 m free bore and peak field on axis of 20 T. One of the main concerns come from the nuclear radiation environment that may influence the stable operation of the coil, as well as its material integrity. Energetic photons cause large radiation heat load, of the order of several kW in the cold mass, and deposit a considerable dose, several tens of MGy. Neutrons cause material damage, at the level of 10-3 DPA. These values are at the present limit of superconducting coil technology. We describe here the conceptual design of the target and capture solenoid, focusing on the HTS cable design, which is largely inspired by the VIPER concept developed at MIT. We show how to address margin and protection, cooling and mechanics specific to the HTS cable selected.

Effects of lateral critical current nonuniformity on stresses in dry-wound high-field REBCO coils

Abstract The distribution of critical current density (jc) in REBCO coated conductors affects the magnetization behaviors and subsequently screening-current-induced stresses, particularly for solenoid magnets in high fields. This paper studies numerically the correlation between lateral jc profile across conductor width and stress distribution in pancake coils. The modeling framework considers bending, winding, thermal contraction, and magnetic forces including coupled electromagnetic-mechanical behaviors, i.e., the deviation of the perpendicular field away from axial direction due to tilting deformation. The lateral nonuniformity is introduced using trapezoidal functions, emulating typical jc profiles originated in pristine tapes and those caused by slitting. First, parametric studies are carried out on the small test coils previously reported in the 'Little Big Coils' (LBC) paper. It is shown that while slitting edge defects have a moderate impact on peak strains, imperfections in the pristine tape with a larger shoulder width can accelerate the penetration process, shifting peak force to the structurally resilient middle section. Similar behaviors are found in the LBC3 case study, suggesting that lateral jc nonuniformity may have contributed to the observed degradation states in pancakes with different slit-edge orientations. Furthermore, the manipulation of lateral jc profile is proposed as a strategy to manage stresses in high field solenoids. This is demonstrated in the design study of a hypothetical REBCO insert. By adjusting the lateral jc distribution and the overall scaling factor, magnet designs with a reasonable current margin and moderate peak strain can be found. The multi-width concept is then applied to allow for a higher operating current and a larger margin for the end pancakes. Albeit being a generic case, this study highlights the sensitivity of peak stresses in high-field magnets to jc distribution. This feature may be taken into account to fine-tune magnet designs and adjust coil assemblies for better overall performance. It also emphasizes the need for careful characterization and effective control of lateral jc distributions in REBCO coated conductors.

Time-dependent Aharonov-Bohm type topological effects on dipoles

Exploring the time-dependent characteristics of AB-type effects holds significant importance in contemporary physics and its practical applications. Here, we delve into the investigation of time-dependent topological effects emerging in AB-type experimental setups. We first analyse the topological effects on magnetic dipoles moving in closed trajectories around the time-varying magnetic field source solenoid, then on electrical dipoles around a time-varying electric field source in 2+1 dimensions without any approximation. Last, we discuss the characteristics of the topological effects by considering the identity and dualities between phases from an integrated perspective.

CORC® wires allowing bending to 20 mm radius with 97.5% retention in critical current and having an engineering current density of 530 A mm−2 at 20 T

Abstract Low-inductance, high-field insert solenoid magnets and 20 T dipole magnets for particle accelerators require flexible cables, wound from high-temperature superconductors (HTS) such as RE-Ba2Cu3O7-δ (REBCO) coated conductors, that allow bending to a 20 mm radius without significant degradation in performance. They require an operating current of at least 5 kA and a high engineering current density (Je) exceeding 500 A/mm2 at 20 T. HTS cable technologies that target such demanding magnet applications so far haven’t been able to meet the combination of these requirements.
Here we present the development of the next generation of Conductor on Round Core (CORC®) wires that improves their bending flexibility by factor of more than 2 compared to previous generation CORC® wires. CORC® wires now allow for a bending radius of 20 mm with only 2 – 3 % performance degradation. They allow bending to a radius of 15 mm with a performance retention of 83.5 %. The performance of 30-tape CORC® wires wound from 2 mm wide REBCO tapes from SuperPower Inc, SuperOx and Shanghai Superconductor Technologies was measured at magnetic fields up to 12 T. The overall performance at high magnetic fields of the next generation of CORC® wires improved by a factor of 1.5 – 1.8, depending on the REBCO tape manufacturer. CORC® wires wound from production REBCO tapes achieved a new record Je of 751 A/mm2 at a current of 8.3 kA at 12 T, and a Je of 530 A/mm2 at a current of 5.8 kA when extrapolated to 20 T. 

EFFECT OF VARIATION OF MAGNETIC INDUCTION SOLENOID VALUES ON TENSILE AND IMPACT STRENGTH FOR WELDING BETWEEN LOW CARBON STEEL AND MEDIUM CARBON STEEL

The use of solenoid magnets in welding processes has attracted attention due to their potential to influence the properties of welded joints. This research investigates the effect of the size of the magnetic induction solenoid on the tensile strength and impact toughness of welds between mild steel and medium carbon steel. Welding experiments were carried out using various sizes of solenoid magnets (0; 1.71mT; 2.11mT; 2.31mT; 2.60mT), and the welding results were tested for tensile strength and impact toughness. The findings show that the size of the magnetic induction solenoid has a significant effect on the mechanical properties of the weld. The larger induction size in this study increased the tensile strength of the welded joint, namely 431.576 N/mm2 without induction and 533.33 N/mm2 with induction. Meanwhile, the impact toughness of welded joints also increases, namely 95.92N.m without treatment and 217.35N.m with induction.

Structural Design and Driving Experiment of an Electromagnetic Drive System for Microrobot

Abstract Controlling the exact positioning and direction of microrobots is a significant challenge in the prospect of microrobot actuation. To solve this problem, the current study created a system that combines solenoid and permanent magnets as an electromagnetic drive mechanism. This system uses a stepping motor to effectively manage the placement of the permanent magnet in the terminal area of solenoid, enabling precise control of its movement. Additionally, a programmable power source is used to adjust the microrobot’s orientation. Driving tests were conducted on a simulated hepatic vein, achieving speeds of up to 1.3mm/s. These results provide valuable references for optimizing future electromagnetic actuation systems.

Spacecraft attitude testbed

Spacecraft attitude determination and control systems (ADCS) stand as a pivotal factor for ensuring the success of missions. As satellite sizes continue to decrease, the need for more intelligent and efficient control algorithms becomes increasingly pronounced. In response to this imperative, we propose the development of a scaled-down testbed specifically designed for evaluating satellites (ACDS). This testbed will demonstrate effective control of a CubeSat through the use of Helmholtz coils, magnetic torquer solenoids, reaction wheels and inexpensive student-made components and available components off the shelf (COTS) in the San Diego State University SPACE Lab. Referred to as the Spacecraft Attitude Testbed (SAT), this custom-designed 3-DoF experimental attitude platform replicates the conditions experienced by a weightless satellite in space. The objective of this research paper is to improve the understanding of how to manufacture a testbed and components like those within this paper, expose some of the issues encountered and improve the outcomes for future academic testbeds. Within this study, the testbed employs torque application to magnetic torquers and reaction wheels to regulate attitude. In summary, this research endeavors to establish a comprehensive and cost-effective testbed platform dedicated to the assessment of spacecraft attitude control and determination systems. It not only seeks to enhance our understanding of advanced control algorithms but also aims to contribute valuable insights into fault detection and adaptive control strategies, ultimately bolstering the efficiency and robustness of satellite operations.

Laser-plasma accelerated proton beam transport system using high-field pulsed solenoid magnet

An energetic proton beam with a high divergence cone angle of ∼10°, generated by the interaction of a 25 fs, 800 nm Ti: Sapphire laser pulse with a thin metal foil target, was transported and focused at a specified distance from the source. A pulsed high-voltage solenoid, which generates a magnetic field of 5.7 T at a current of 8 kA, was developed in-house for this purpose. The profile of the proton beam was monitored online at various positions using a combination of a fast thin plastic scintillator and a CCD camera. The effect of solenoid misalignment on the focused proton beam was also investigated experimentally. In addition, the proton beam was transported out of the vacuum chamber into the ambient air for radiography application. A proton flux of ∼2 × 108 protons (energy >4 MeV) was transported and focused at a distance of 1.27 m from the target with a transmission efficiency of 30 % in a single shot. Detailed simulations incorporating particle tracing and transfer matrix method were performed to highlight the role of beam chromaticity and the impact of spherical harmonics on the focusing characteristics of the solenoid. The simulation results qualitatively reproduce the experimental observations. The solenoid provides energy-selective proton focusing for a broad energy proton beam. The proton beam was used for the radiography of reference meshes and has the potential to be used for radiobiological irradiation studies.

Study on ion current density of different species in laser produced plasma in a solenoid magnet

A solenoid magnetic field along the expanding laser-produced plasma is an essential technique of the laser ion source. The solenoid field can increase ion beam current at beam extraction point by a factor of 2 to over 100 by confining moving laser produced plasma in transverse direction. This technique is used everywhere from development lab to operational machine for user operation. However, the motion of ions in laser produced plasma is not fully understood. In this study, we experimentally investigated the motion of ions in a solenoid magnet (inner diameter 102 mm, coil length 1980 mm) for Al, Fe, and Ta targets. Using the following three conditions: full solenoid bore, a φ51 mm collimator on the solenoid axis, and a thin-wall φ51 mm tube at the bottom of the solenoid, we found that extracting ions at off-axis position (20∼30 mm from the solenoid axis in this study) can enhance ion intensity by a factor of three or more. We continue to investigate ion motion in a solenoid field to develop better laser ion source design.

Ti beam extraction from a laser plasma focused by a magnetic field of a solenoid

Laser ion sources (LISs) have the advantages of generating plasma from various solid targets and quickly switching the ion species by changing the target. Given these features, we aimed to develop a LIS for an ion implanter that requires a wide variety of ion species. The plasma generated by the LIS diffuses three-dimensionally with a wide angular distribution, such that only a small fraction of the generated ions reaching the extraction electrode aperture is extracted as a beam. With this procedure, the beam intensity is insufficient for the implanter LIS, which uses a laser with lower energy than the conventional LIS. To obtain a higher beam intensity by increasing the number of ions reaching the beam extraction electrode aperture, a plasma transport system with a linear solenoid magnet was installed immediately after the LIS chamber to focus the plasma by a magnetic field. In the Ti plasma focusing experiment using this system, the beam intensity increased up to 6.7 times compared to that of the case without a magnetic field. This result demonstrates that plasma focusing by a magnetic field is effective for increasing the beam intensity.

Numerical study on the electromagnetic characteristics of multi-layer CORC cables

Due to the high isotropy and low AC losses, the multi-layer conductor on round core (CORC) cable is a good candidate for high field magnets, such as central solenoid magnets in fusion. Considering the difficulty in experimental measurement, numerical model is an effective way to illustrate the electromagnetic characteristics of the multi-layer CORC cable and provide further insights into its working performance. In this work, a 3D finite element model based on H formulation is proposed to simulate a CORC cable with as many as 18 layers considering electromagnetic coupling. The validity of the model has been verified by experimental results. Based on the proposed model, the DC transport current distribution characteristics and charge-discharge loss characteristics of multi-layer CORC cables wound in the same and opposite winding directions are investigated respectively. This work can provide an important reference for the design of multi-layer CORC cables for high-current or high-field application.

A beam line setup for flash radiation therapy with focused electron beams at the PITZ facility at desy in zeuthen: Basic concept and dosimetry simulations

The objective of this study is demonstration of the principal possibility to increase the electron beam dose deposition at the certain depth of the sample for radiation therapy purposes. Electron bunches of 22 MeV within train generated at PITZ are focused inside the sample using a dedicated fast deflector and a solenoid magnet. To explore the capabilities of the proposed setup, dose distributions are calculated for multiple electron bunches focused in a single point inside a water phantom. Electron beam focusing produces dose peaks with a tunable maximal dose depth which is interesting for healthy tissue sparing at the surface and enhancing treatment quality. The duration of the full bunch train is 1 ms. During this time interval, the FLASH effect could be efficiently triggered inside the irradiated target volume. Monte Carlo simulations based on the FLUKA code were performed to evaluate the depth dose curves distributions in a water phantom. Using the PITZ electron beam parameters, simulations have shown the possibility to produce a peak dose in water seven times higher than compared to the dose at the surface. Moreover, the RMS size homogeneous area around the maximal dose is approximately 25 mm.

Integrable Magnetic Fluid Hyperthermia Systems for 3D Magnetic Particle Imaging.

Background: Combining magnetic particle imaging (MPI) and magnetic fluid hyperthermia (MFH) offers the ability to perform localized hyperthermia and magnetic particle imaging-assisted thermometry of hyperthermia treatment. This allows precise regional selective heating inside the body without invasive interventions. In current MPI-MFH platforms, separate systems are used, which require object transfer from one system to another. Here, we present the design, development and evaluation process for integrable MFH platforms, which extends a commercial MPI scanner with the functionality of MFH. Methods: The biggest issue of integrating magnetic fluid hyperthermia platforms into a magnetic particle imaging system is the magnetic coupling of the devices, which induces high voltage in the imaging system, and is harming its components. In this paper, we use a self-compensation approach derived from heuristic algorithms to protect the magnetic particle imaging scanner. The integrable platforms are evaluated regarding electrical and magnetic characteristics, cooling capability, field strength, the magnetic coupling to a replica of the magnetic particle imaging system's main solenoid and particle heating. Results: The MFH platforms generate suitable magnetic fields for the magnetic heating of particles and are compatible with a commercial magnetic particle imaging scanner. In combination with the imaging system, selective heating with a gradient field and steerable heating positioning using the MPI focus fields are possible. Conclusion: The proposed MFH platforms serve as a therapeutic tool to unlock the MFH functionality of a commercial magnetic particle imaging scanner, enabling its use in future preclinical trials of MPI-guided, spatially selective magnetic hyperthermia therapy.

Development of a solenoid magnet for emittance compensation

This paper explores the implementation of a solenoid field to achieve electron beam focusing and compensation of transverse emittance, which is generated from photocathode RF gun. An extensive investigation was conducted to determine the optimal solenoid magnetic field required for focusing an electron bunch with a charge of 0.5 nC. A magnetic field strength of 0.25 T was chosen for emittance compensation, enabling the reduction of emittance to below 1.20 mm-mrad at the end of linac. The engineering design of the solenoid magnet for this system is presented in detail, ensuring precise dimensional tolerances within the range of ±30 µm. To ensure its effectiveness and reliability, extensive thermal and mechanical analyses were conducted. Currently, the prototype solenoid magnet is in the fabrication process.

Enhancing resonant circular-section haloscopes for dark matter axion detection: approaches and limitations in volume expansion

Haloscopes, microwave resonant cavities utilized in detecting dark matter axions within powerful static magnetic fields, are pivotal in modern astrophysical research. This paper delves into the realm of cylindrical geometries, investigating techniques to augment volume and enhance compatibility with dipole or solenoid magnets. The study explores volume constraints in two categories of haloscope designs: those reliant on single cavities and those employing multicavities. In both categories, strategies to increase the expanse of elongated structures are elucidated. For multicavities, the optimization of space within magnets is explored through 1D configurations. Three subcavity stacking approaches are investigated, while the foray into 2D and 3D geometries lays the groundwork for future topological developments. The results underscore the efficacy of these methods, revealing substantial room for progress in cylindrical haloscope design. Notably, an elongated single cavity design attains a three-order magnitude increase in volume compared to a WC-109 standard waveguide-based single cavity. Diverse prototypes featuring single cavities, 1D, 2D, and 3D multicavities highlight the feasibility of leveraging these geometries to magnify the volume of tangible haloscope implementations.

Towards a compact all-optical terahertz-driven electron source

In this study, we propose a physical design of a compact all-optical terahertz (THz)-driven electron source. The 300-mm accelerator beamline, powered by a Joule-level laser system, can be easily integrated into the tabletop scale. A THz-driven electron gun, a tapered dielectric-loaded cylindrical waveguide, THz-driven bunch compressors, and permanent magnetic solenoids (PMSs) have been designed and optimized. Dynamic simulations show that the electron source can deliver 19 fC electron beams at 3 MeV, with a normalized transverse emittance of 0.079 π.mm.mrad. A minimum relative energy spread of 0.04% or a minimum root-mean-square (RMS) bunch length of 6.1 fs can be achieved. Sensitivity analysis shows that the THz-driven electron source can effectively work with a laser power jitter within 1.5%. Simulation studies also reveal the potential of the designed THz-driven electron source for achieving high-quality ultrafast electron diffraction (UED). Prototype THz-driven electron guns have been fabricated and are currently under testing, and more comprehensive results will be reported in future works.

Overview of the Electromagnetic Optimization Literature of Superconducting Solenoidal Magnets and Coils

This article is a narrative and systematic review on the electromagnetic optimization literature of superconducting solenoidal magnets and coils. Superconducting solenoids are the basis of magnetic resonance imaging machines and superconducting energy storage systems. As the literature has evolved and many optimization techniques have been used, in this paper, we review the evolution of techniques used to achieve a defined field homogeneity, to reduce conductor's length, achieve a defined field intensity, increase stored energy, and optimize secondary aspects. We present chronologically, discuss and compare the referenced literature, which is also categorized in tables based on the optimization target. The tables present the optimization type, the used technique, the contribution of the paper, and the material. We discuss the existing literature gaps and the optimization techniques applied for designing the two most common machines, i.e., magnetic resonance imaging and superconducting magnetic energy storage devices, and we conclude that modern techniques are not used frequently, compared to techniques that predate the year 2000.

An infrared light-guide based target positioning system for operation in a harsh environment

In the P¯ANDA experiment’s hypernuclear and hyperatom setup, a positioning system for the primary production target is required, which will be located in the center of the solenoid magnet, in ultra-high vacuum, and exposed to high radiation levels. In this work, a prototype for a positioning sensor was built using a bisected light guide for infrared light and a low-priced readout system based on microcontrollers. In contrast to many modern positioning systems that require electronics in direct proximity, this setup has no active electronic components close to the moving parts. The prototype system was operated with a resolution of better than 5µm, and with a repeatability of better than ±18µm in a total of 14000 measurements. The demonstrated performance is by far satisfying the positioning requirement of ±300µm in the hypernuclear and hyperatom setup at P¯ANDA.