Quadrupole Coils Research Articles

A novel bipolar coil structure with high interoperability performance for electric vehicle wireless charging systems

SummaryThe magnetic couplers play an important role in electric vehicle (EV) wireless power transfer (WPT) systems. Conversational coupling structures are mainly based on unipolar, bipolar, and quadrupole coils, and the interoperability among them cannot be achieved. To solve the interoperability problem in the coupling structure, a novel bipolar coil structure is proposed in this paper. Energy transfer with unipolar and bipolar coils is achieved by interconnecting unipolar and bipolar types crosswise in the same plane and combining them with the corresponding topologies. They are connected in series on the dc side. An experimental prototype is built to verify the interoperability performance of the proposed novel bipolar coil structure. The proposed novel bipolar coil structure can be compatible with unipolar, bipolar, and quadrupole coils and achieve a maximum dc‐dc efficiency of more than 85%.

A Quadrupole Receiving Coil With Series-Connected Diode Rectifiers for Interoperability of Nonpolarized and Polarized Transmitting Coils

Non-polarized and polarized coils are utilized in an electric vehicles (EV) wireless charging system. These coils are decoupled from each other at the central position, leading to interoperability issues. This letter proposes a new decoupling method and a quadrupole receiving coil with series connected diode rectifiers for interoperability purposes. Decoupling windings are added to achieve decoupling of the four receiving poles. The total mutual inductance between the transmitting coil and the quadrupole receiving coil is the summation of the absolute values of the mutual inductances between the transmitting coil and the four receiving poles. In this way, the proposed quadrupole coil can be tolerant with not only the non-polarized transmitting coil, but also with the polarized transmitting coils along two perpendicular directions. The experimental results confirm that a large coupling and efficient power transfer can be achieved with the non-polarized coil and the polarized coil placed at two perpendicular directions with good misalignment tolerance.

A metal object detection system for electric vehicle wireless charging with quadrupole detection coils

In the practical application of magnetic coupling wireless charging technology, the absence of direct contact between the receiver and transmitter usually leads to metal objects (MOs) entering the charging area. The strong magnetic field between the receiver and transmitter causes eddy current effects and generates large amounts of heat in MOs, which may lead to serious hazards such as fires, so it is necessary to detect accidental entry of MOs. In this paper, a novel detection coil layout suitable for wireless charging of electric vehicles (EVs) has been proposed, which consists of multiple quadrupole coils arranged to achieve decoupling from the receiver and the transmitter to minimize the effect on the system efficiency. The influence of the presence of MOs on the equivalent inductance and equivalent resistance of the quadrupole detection coil has been deduced. The simulation results show that the maximum self-inductance change rate of the proposed detection coil reaches 28.11%, and a high self-inductance variation rate is also achieved at the edge of the detection coil.

DCT&CCT Superconducting Multiplets for HIAF-HFRS

HIAF (High Intensity heavy ion Accelerator Facility) is the new generation heavy ion accelerator under construction in China. The HFRS (FRagment Separator of HIAF) is a fragment separator and also a transfer-line between the Booster Ring and the Spectrometer ring, which has magnetic rigidity up to 25 Tm. HFRS magnet system is composed of 11 superconducting dipoles and 13 sets of triplets. Several multipole magnets (an octupole coil, a quadrupole coil, and a sextupole coil) are nested together to compact the length of the HFRS-line. All of them feature high field gradients (13 T/m, 25 T/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> , 105 T/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> ) and large bores (320 mm). To reduce the cold mass and ensure the field quality, the whole multipole magnets are all designed with coil-dominated magnets of CCT (Canted Cosine Theta) and DCT (Discrete Cosine Theta). This paper will introduce the general design process of an HFRS multipole module. The development process and test results of the prototype will be presented.

Concept Design of a Superconducting Magnet for a Compact Heavy-Ion Synchrotron

A compact synchrotron is now under development at the National Institutes for Quantum Science and Technology (QST), with the goal of downsizing the heavy-ion therapy system with superconducting magnets conduction-cooled by GM cryocoolers. The synchrotron is required to accelerate several kinds of heavy-ion beams from 4 MeV/u to 430 MeV/u. A superconducting magnet with both dipole and quadrupole coils is adopted to generate a dipole field from 0.3 to 3.5 T and a quadrupole field from 0.1 to 1.5 T/m with a ramp rate of 0.6 T/s. A coil winding pattern and iron yoke are optimized to achieve field homogeneity in the required area. For the small-scale synchrotron, the coil ends are optimized with a novel parameter combining the beta function and multipole errors considering the beam dynamics.

Design and Optimization of the Superconducting Quadrupole Magnet Q1a in CEPC Interaction Region

To study the properties of Higgs, scientists from the Institute of High Energy Physics have proposed to build the Circular Electron Positron Collider (CEPC) and published a conceptual design report in 2018. In order to improve the collision luminosity of CEPC, the upgrade of the final focus system in the interaction region is on-going. According to the latest physical requirements of superconducting magnets in the CEPC interaction region, a high gradient, double-aperture quadrupole magnet Q1a is required, which is 1.9 m from the interaction point. In this paper, we present the magnetic design of superconducting quadrupole magnet Q1a, and discuss the advantages and disadvantages of the three kinds of quadrupole coil structures, including cos2θ coil, CCT coil, and racetrack coil. Low-temperature superconductor NbTi is used in our magnet design process. In addition, optimization is performed to greatly reduce the weight of the magnet.

Design and Field Performance of Octupole Magnet With Skew Quadrupole Component in HEPS

The High Energy Photo Source (HEPS) is being built in China and the magnets are in batch production. The octupole magnets with skew quadrupole component used in the storage ring have been designed and manufactured. The octupole has an aperture of 30 mm, a field gradient of 735000 T/m <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> and a length of 0.26 m. In this paper, detailed magnetic design of HEPS octupole magnets is presented. Different design schemes of the skew quadrupole coils are compared, and the temperature effect on magnetic center and the integral field in the first batch of octupole magnets are also given. In addition, the influence of the combined power-on mode on the magnetic field is studied.

Numerical Optimization of the FFS Quadrupole

Three experiments HIHEX (Heavy Ion Heating and Expansion), LAPLAS (Laboratory Planetary Sciences) and PRIOR (Proton Microscope for FAIR) are proposed by the HED&#x0040;FAIR (High Energy Density at Facility for Antiproton and Ion Research) collaboration to study matter under extreme conditions of temperature and pressure at the FAIR facility in Darmstadt, Germany. A special beam strong final focusing and imaging system has to be installed at the end of the HED&#x0040;FAIR beam line. One of the main components of these systems are four wide-aperture quadrupoles, which have to provide a focal spot of about a millimeter size. Within the framework of collaboration between IHEP and GSI at IHEP, these magnets will be designed and produced. The main parameters of the quadrupoles are: DC operating mode; the coil inner diameter is 260 mm; the minimal distance between quadrupole centers of two nearby magnets is 2500 mm; the integral of field gradient is 66 T. The prototype of the quadrupole coil is manufactured and its mechanical characteristics is studied. The 2D and 3D geometry of large-aperture quadrupole is optimized taking into account these studies. The general characteristics of this geometry are presented in this article.

Computer Simulation of the Mechanical Behavior of the FFS Superconducting Quadrupole Coil

Computer Simulation of the Mechanical Behavior of the FFS Superconducting Quadrupole Coil

Harmonic Suppression Study on Twin Aperture CCT Type Superconducting Quadrupole for CEPC Interaction Region

Iron-free twin-aperture superconducting quadrupole in the interaction region is a key technology to increase the luminosity of high-energy future colliders, such as the circular electron-positron collider that China will build in the next ten years with a center-of-mass energy of 240 GeV and a small crossing angle of 33 mrad in the interaction region. The final focusing quadrupole QD0, which is 2.2 m away from the interaction point, only has a 72 mm beam separation distance at the front end of the magnet. Because of the tight space, canted cosine theta coil type is the best selection, where the coil can be wound directly on the coil former in a fixed inclination angle. For QD0, the superconducting quadrupole coils for the two apertures are nearly in contact; high-order harmonics will be produced by magnetic field crosstalk and should be canceled out at the design stage. This article will present the design study for a pair of 400 mm long QD0 prototype, where we deliberately introduce some opposite harmonics to optimize the coil configuration so as to cancel out the unwanted harmonics.

Increasing the length of free-falling path with homogeneous bias field for compact cold atom interferometers by configuring MOT coils

In a cold atom interferometer, a bias magnetic field, usually generated by a solenoid or a set of coils, is used to select specific Raman transitions of atoms in the interference region, and its inhomogeneity leads to a Zeeman-effect-induced error for the measurement. To improve the measurement’s accuracy further, we propose a simple method to compensate for the non-uniformity of the bias field by reversing the direction and tuning the value of the current running through the pair of quadrupole coils used for magneto-optical trap (MOT). To smoothen the field with MOT coils, the current applied should be controlled timely and precisely, which was done with a fast-responding electric circuit we designed and built. We also used Raman spectroscopy to characterize the magnetic field profile without and with our method applied, which shows that the length of the homogeneous field (where the fluctuation of magnetic strength is less than 10%) is expanded from 81.87 mm to 101.64 mm. From our calculations, with the free evolution time T of 30 ms, the quadratic Zeeman-effect-induced phase shift Δϕzeeman can be reduced by 76%, which reduces the quadratic Zeeman-effect-induced error of measured gravity Δgzeeman to a quarter of that without our method applied (from 1.745 mGal to 0.418 mGal). Simulation and experiment prove that this method is effective. This method can also be used in other atom interferometers, especially compact systems.

Final Focus Superconducting Magnets for CEPC

Final focus high gradient quadrupole magnets QD0 and QF1 are key devices of the Proposed Circular Electron Positron Collider (CEPC). They are both double aperture superconducting quadrupoles with held gradients of 136 T/m and 110 T/m, respectively. The angles between the two aperture centerlines are both 33 mrad. Though the two apertures of QD0 is in close proximity, the problem of multipole helds caused by held crosstalk is successfully solved by using cos2θ quadrupole coil with iron core. The quadrupol magnets are operated inside the magnetic held of the Detector solenoid magnet, so superconducting anti-solenoid is required to generate solenoid held that can cancel the Detector solenoid held. The hrst step of the R&D is to develop a QD0 short model magnet with a magnetic length of 0.5 m. In this paper, the layout and magnetic design of CEPC hnal focus superconducting magnets are described, and the detailed design of the QD0 short model magnet is presented.

Vacuum Pressure Impregnation Setup at CERN for Nb3Sn Coils

The CERN Large Magnet Facility (LMF) is currently producing 5.5 m long 11 Tesla dipole and 7.2 m long MQXFB quadrupole coils for the HL-LHC project. Both coil types are fabricated with Nb3Sn conductor with the so-called wind and react technique. These coils require a vacuum pressure impregnation process to form the final insulation and to give the final dimensions. The paper will present the impregnation process applied at CERN focusing in particular on the hardware. The impregnation process and its reproducibility are shown, together with ongoing developments. Furthermore, the LMF impregnation infrastructure and recent applied upgrades are described, aiming for a reliable process workflow based on a modular hardware with an improved interchangeability.

Magnetic Design and Fabrication of Warm-Iron Normal-Conducting Quadrupole Magnets for ReA3 HEBT Line at NSCL

The ReA3 reaccelerator facility at the National Superconducting Cyclotron Laboratory (NSCL), Michigan State University (MSU), East Lansing, MI, USA, provides unique access to high-quality beams of a wide variety of isotopes for scientific research. The high-energy beam transport (HEBT) line from the ReA3 superconducting linear accelerator to the three experimental end stations consists of several iron-dominated normal-conducting quadrupole magnets, dipole magnets, and also combined-function horizontal and vertical corrector magnets. This article focuses on the design and fabrication of a new type of normal-conducting quadrupole magnet with cylindrical split yoke structure and standard quadrupole coils. Electromagnetic simulation results demonstrate that the magnet design fulfills the performance requirements for the ReA3 HEBT beamline. We present the coil fabrication and mechanical assembly details of the magnet. Our analysis results show that the hydraulic requirements for the coils are met.

Evaluation of radiation environment in the target area of fragment separator HFRS at HIAF

In this work, the radiation environment in the target area of a fragment separator is evaluated using FLUKA code. The energy deposition in quadrupole coils is presented to provide guidance for a radiation-resistant magnets design. Results show that neutrons dominate in the prompt radiation field. A compact shielding design is recommended for high radiation areas along with the minimization of air activation in the tunnel in order to minimize the radiation effect on nearby beam lines. The displacements per atom results for the graphite target and copper coils indicate that the effect is insignificant. In addition, the activation level of the target is estimated for workers under possible hands-on maintenance condition.

A dynamic magneto-optical trap for atom chips

We describe a dynamic magneto-optical trap (MOT) suitable for the use with vacuum systems in which optical access is limited to a single window. This technique facilitates the long-standing desire of producing integrated atom chips, many of which are likely to have severely restricted optical access compared with conventional vacuum chambers. This ‘switching-MOT’ relies on the synchronized pulsing of optical and magnetic fields at audio frequencies. The trap’s beam geometry is obtained using a planar mirror surface, and does not require a patterned substrate or bulky optics inside the vacuum chamber. Central to the design is a novel magnetic field geometry that requires no external quadrupole or bias coils which leads toward a very compact system. We have implemented the trap for 85Rb and shown that it is capable of capturing 2 million atoms and directly cooling below the Doppler temperature.

Design of Superconducting Magnets for a Compact Carbon Gantry

For widespread use of rotating gantries for carbon radiotherapy, we designed a new compact gantry. This new gantry consists of three combined-function superconducting magnets having a bending angle of 90°. The dipole field of the superconducting magnets is set to be B <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">max</sub> = 5.02 T, corresponding to a bending radius of 1.32 m for transporting carbon ions having kinetic energy of 430 MeV/u. The superconducting magnet also has three independent superconducting quadrupole coils, which are to be wound inside the dipole coil for beam focusing. The dipole and quadrupole coils are electrically isolated in the magnet and connected to independent power supplies so that each field component can be independently excited. Having used the combined-function superconducting magnets, the size of the rotating gantry would become very compact; the length and radius are 5.1 and 4.0 m, respectively. The magnetic field distributions of the superconducting magnets were calculated with a 3-D electromagnetic field solver, Opera-3d code. With calculated fields, the superconducting coils were designed to obtain uniform field distributions. In this paper, the design of this compact rotating gantry and the superconducting magnets is presented.

Bose-Einstein condensation in an electro-pneumatically transformed quadrupole-Ioffe magnetic trap

We report a novel approach for preparing a Bose–Einstein condensate (BEC) of 87Rb atoms using an electro-pneumatically driven transfer of atoms into a quadrupole-Ioffe magnetic trap (QUIC trap). More than 5 × atoms from a magneto-optical trap are loaded into a spherical quadrupole trap and then transferred into an Ioffe trap by moving the Ioffe coil towards the center of the quadrupole coil thereby changing the distance between the quadrupole trap center and the Ioffe coil. The transfer efficiency is more than 80%. This approach is different from the conventional approach of loading the atoms into a QUIC trap wherein the spherical quadrupole trap is transformed into a QUIC trap by changing the currents in the quadrupole and the Ioffe coils. The phase space density is then increased by forced rf evaporative cooling to achieve Bose–Einstein condensation of more than 105 atoms.

Experience on Series Production of the Superconducting Magnet Package for the Linear Accelerator of the European XFEL

The procurement of 103 superconducting magnet packages is part of the Spanish in-kind contribution to the European X-FEL. Each package consists of a main superferric quadrupole and two steerers, vertical and horizontal, fed by conduction-cooled current leads and enclosed in a stainless steel vessel. The operation temperature is 2 K, as they are embedded in a superfluid helium bath. The magnetic and mechanical designs are published elsewhere. The magnets are being produced in the Spanish company ANTEC, while the vessels are fabricated by another Spanish company, Trinos Vacuum-Projects, which is also responsible for the integration, under the supervision of CIEMAT. The helium vessel manufacturer needs to accomplish the requirements given by the European Pressure Equipment Directive, namely PED 97/23/EC. This paper describes the series fabrication techniques, the production follow-up, the quality assurance, and the magnet testing at the manufacturer site. Cold tests are realized at DESY premises. The main problems found during the fabrication of the first half of the series are also reported: 1) the reproducibility of the quadrupole coil dimensions; 2) the accuracy of the beam position monitor housing after final welding of the vessel; and 3) the minimization of the magnetization effects on the transfer function of the magnets.

The Installation and Commissioning of the Advanced Light Source Combined-Function Harmonic Sextupoles for the Low Emittance Upgrade

The Advanced Light Source (ALS) is a third-generation light source in operation since 1993. This light source is providing state-of-the-art performance to more than 40 beamlines and their users, due to the upgrades that have been completed over the last few years. The storage ring upgrade project that is developed here will allow the ALS to provide the 40 beamline users with higher photon beam brightness (factor of 2 or 3) by having its storage ring lattice modified. Forty-eight harmonic sextupole magnets with integrated dipole correctors and skew quadrupole coils will be introduced, which will require a level of installation activity not seen at the ALS since its original construction in 1991. Introducing new combined-function magnets in an existing storage ring is a challenge due to the limited space available and a balance had to be found between magnet performance and spatial constraints. After an introduction reviewing the characteristics of the three design families of the 48 combined-function magnets, the magnet fabrication and installation are developed along with analyses based on the magnetic measurements and the ALS storage ring commissioning results.