Magnetic measurement with coils and wires

Walckiers, L.

doi:10.48550/arxiv.1104.3784

Cited by 3 publications

(5 citation statements)

References 14 publications

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“…The normalized gradient error obtained from Radia is below 5 × 10 −4 within the GFR of ±10 mm. Usually, multipole errors or field harmonics of multipole magnets can be accurately measured using a rotating coil or a stretched wire technique [22][23][24]. The measuring coils are rotated in the magnet aperture, and an induced voltage from the change in magnetic flux through the coils is measured.…”

Section: Magnetic Field Measurementmentioning

confidence: 99%

Development of Type A Quadrupole Magnet for Siam Photon Source II

Prawanta,

Leetha,

Singthong

et al. 2023

Particles

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A prototype of a type A quadrupole magnet has been designed and manufactured for the 3 GeV storage ring of Siam Photon Source II, the second synchrotron light source in Thailand. The required quadrupole gradient is 51 T/m with the magnet effective length being 162 mm. Magnet modeling and magnetic field calculation were performed using Radia and Opera-3D. The bore radius of the magnet is 16 mm. The magnet will be operated at the excitation of 5544 A-turns. A mechanical analysis of the magnet structure was performed in SOLIDWORKS and ANSYS, where the maximum deformation of 0.003 mm was found at the magnet poles, and the first-mode natural frequency was higher than 100 Hz. The magnet yoke is made of AISI 1006 low-carbon steel with a fabrication tolerance of ±0.020 mm. Magnet coils are water-cooled and made of high-purity copper. The temperature rise of the coils was below 3.0 °C at the maximum excitation of 6664 A-turns, which is 20% above the operating point. Magnetic field measurement was carried out using the Hall probe technique. The measured magnetic field and coil temperature of the prototype show good agreement with the calculations.

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Section: Magnetic Field Measurementmentioning

confidence: 99%

Development of Type A Quadrupole Magnet for Siam Photon Source II

Prawanta,

Leetha,

Singthong

et al. 2023

Particles

View full text Add to dashboard Cite

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“…The air gap of a magnet can be modeled as a region free of current sources. Considering a cylindrical volume, coaxial with the gap, sufficiently extended so that the field at both ends can be considered to vanish, the integral magnetic field density satisfies the

Laplace equation and can be described by a complex-valued harmonic field expansion in a circular domain of radius

, also called the reference radius [ 4 ]. For

where

and

represent the vertical and horizontal field components as a function of the position,

is the n -th complex harmonic coefficient, and

and

are the normal and skew harmonic coefficients, respectively, expressed in tesla at the reference radius

.…”

Section: Background Theorymentioning

confidence: 99%

“…Assessment of the field quality is performed through accurate field measurements, necessary to determine the presence of construction errors, coil deformations due to electromagnetic forces, dynamical effects such as eddy currents in the bulk of the yoke, ferromagnetic hysteresis, and iron saturation. Complementary methods exist to perform magnetic measurements [ 4 ], each one optimized for a determined quantity of interest, such as integrated field, field harmonics, or time evolution of the field in the magnet gap.…”

Section: Introductionmentioning

confidence: 99%

“…Increasing the aspect ratio

leads very rapidly to a high sag and undesired flexural oscillations during the rotation, which affect the accuracy of the measured harmonics [ 16 ]. The impact of such mechanical imperfections can be mitigated by the coil bucking technique [ 4 ], which, however, requires very tight tolerances on the geometry of the coils. In addition, the small size of the rotating shaft and the constraints on the density of coil turns, which can vary typically between 100 (for multi-layer PCBs) and 400 turns/mm

(for multi-wire flat cables), reduce the magnetometer coil sensitivity, especially on the higher-order harmonics.…”

Section: Introductionmentioning

confidence: 99%

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Rotating-Coil Measurement System for Small-Bore-Diameter Magnet Characterization

Lauria

Arpaïa

Buzio

et al. 2022

Sensors

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Rotating-coil measurement systems are widely used to measure the multipolar fields of particle accelerator magnets. This paper presents a rotating-coil measurement system that aims at providing a complete data set for the characterization of quadrupole magnets with small bore diameters (26 mm). The PCB magnetometer design represents a challenging goal for this type of transducer. It is characterized by an aspect ratio 30% higher than the state of the art, imposed by the reduced dimension of the external radius of the rotating shaft and the necessity of covering the entire magnet effective length (500 mm or higher). The system design required a novel design for the mechanical asset, also considering the innovation represented by the commercial carbon fiber tube, housing the PCB magnetometer. Moreover, the measurement system is based primarily on standard and commercially available components, with simplified control and post-processing software applications. The system and its components are cross-calibrated using a stretched-wire system and another rotating-coil system. The measurement precision is established in a measurement campaign performed on a quadrupole magnet characterized by an inner bore diameter of 45 mm.

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“…All the quadrupole magnets that belong to the ATF2 FFS except the FD are denoted as QEA magnets. A first measurement campaign of the ATF2 FFS magnets was conducted at IHEP in 2006 during the manufacturing stage using the harmonic coil measurement technique [105]. The rotating coil measurement provides the integrated strength and the tilt of each multipole component present in the magnet.…”

Section: Initial Estimates Of Multipole Components Of the Atf2 Magnetsmentioning

confidence: 99%

Design and higher order optimisation of final focus systems for linear colliders

Marín Lacoma

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The accelerator and particle physics communities are considering a lepton Linear Collider LC as the most appropriate machine to carry out high precision particle physics research in the TeV energy regime. The Compact Linear Collider CLIC and the International Linear Collider ILC are the two proposals for the future e+e- LC. Both designs achieve a luminosity L above 10^(34) cm-2 s-1 at the interaction point IP, satisfying the particle physics requirements. The LC consists of different systems, being the Final Focus System FFS the last one before colliding the beam at the IP. It is responsible to focus the beams at sizes in the range of nanometres by means of the Final Doublet FD. The FFS designs of the CLIC and ILC projects are based on a new local chromaticity correction scheme which has never been experimentally tested before. The Accelerator Test Facility ATF2 at KEK (Japan) aims to experimentally verify the feasibility of the FFS based on this novel scheme. The present thesis is devoted to the design and higher order optimisation of FFS for linear colliders based on the local chromaticity correction scheme. The CLIC design luminosity L0 is 5.9·10^(34) cm-2 s-1 assuming head-on collisions. However the beams cross each other at the IP forming an angle of 20 mrad. Due to this crossing scheme the luminosity would be reduced by 90%. Crab cavities are dedicated to tilt the bunches in order to provide head-on like collisions preserving the design L0. In this thesis different solutions that recover the design luminosity for the CLIC FFS are proposed. The designs of a new ATF2 Nominal and Ultra-low beta* lattices, to test the feasibility of the ILC and CLIC FFS respectively, are presented in this thesis. The expected IP vertical beam sizes sy* for these lattices are 38 and 23 nm respectively, at this beam size regime the magnetic field quality of the FFS magnets is a concern. Indeed, the evaluated sy* with the measured multipole components is 100% for the Nominal lattice and 400% for the Ultra-low beta* lattice. The study of the higher order aberrations performed in this thesis is crucial for identifying possible cures that minimise the observed beam size growth. Different solutions have been studied: (i) replacing the FD by better field quality magnets, (ii) swapping the ATF2 quadrupole magnets according to their skew sextupole component and (iii) modifying the lattice optics. The new lattice designs ATF2 Bx2.5By1.0 and ATF2 Ultra-low betay* are based on the prosposed solutions. The impact of the multipoles components is effectively minimsed for both new designs, achieving a sy* equal to 38 and 27 nm ,respectively. The tuning study of the FFS determines its feasibility under realistic error conditions. 100 machines with different initial error configurations are used to address this problem. The tuning simulation study for the alternative CLIC FFS design takes into account BPM resolution, the effect of synchrotron radiation and the misalignment errors of the magnets, being the later a critical parameter on the tuning performance of the system. The motion of the magnetic centre when shunting the quadrupole magnet might represent a limiting factor for further improvement of its alignment. Dedicated measurements at ATF2 have shown a motion of the magnetic centre below 1 micrometre for a shunting variation of 20%. Under this alignment condition the tuning study of the CLIC FFS shows that 80% of the machines reach a L equal or above than L0. The errors included in the tuning study of the ATF2 lattices are misalignments, tilts and miss-powering of the ATF2 FFS magnets. The simulated tuning results show that 80% of the machines reach a final sy* that does not exceed in more than 11% and 35% the design sy* for the ATF2 Bx2.5By1.0 and Ultra-low beta_y* lattices respectively. These results demonstrate the theoretical feasebility of FFS based on the novel chromaticity correction scheme.

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Magnetic measurement with coils and wires

Cited by 3 publications

References 14 publications

Development of Type A Quadrupole Magnet for Siam Photon Source II

Development of Type A Quadrupole Magnet for Siam Photon Source II

Rotating-Coil Measurement System for Small-Bore-Diameter Magnet Characterization

Design and higher order optimisation of final focus systems for linear colliders

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