A rotating coil transducer for magnetic field mapping

Arpaïa, Pasquale; Buzio, Marco; Matteis, Ernesto De; Russenschuck, Stephan

doi:10.1088/1748-0221/10/06/p06006

Cited by 5 publications

(6 citation statements)

References 25 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The system, mounted on a rail and equipped with a linear encoder, is shown in Figure 2. The metrological characterization of the system was published in Arpaia et al (2015a).…”

Section: 1mentioning

confidence: 99%

“…We have therefore developed measurement methods based on moving induction-coil arrays, longitudinal and transversal rotating-coil scanners (Arpaia et al, 2015a) and induction-coil transducers for solenoidal magnets (Arpaia et al, 2015b). These methods require, however, a sophisticated post-processing step based on the regularity conditions of electromagnetic fields in simply connected, source-free domains.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Rotating- and translating-coil magnetometers for extracting pseudo-multipoles in accelerator magnets

Russenschuck

2017

COMPEL

View full text Add to dashboard Cite

Purpose The purpose of this paper is to establish the mathematical foundations of magnetic measurement methods based on translating-coil and rotating-coil magnetometers for accelerator magnets and solenoids. These field transducers allow a longitudinal scanning of the field distribution, but require a sophisticated post-processing step to extract the coefficients of the Fourier–Bessel series (known as pseudo-multipoles or generalized gradients) as well as a novel design of the rotating coil magnetometers. Design/methodology/approach Calculating the transversal field harmonics as a function of the longitudinal position in the magnet, or measuring these harmonics with a very short, rotating induction-coil scanner, allows the extraction of the coefficients of a Fourier–Bessel series, which can then be used in the thin lens approximation of the end regions of accelerator magnets. Findings The extraction of the leading term in the Fourier–Bessel series requires the solution of a differential equation by means of a Fourier transform. This yields a natural way to de-convolute the measured distribution of the multipole content. The author has shown that the measurement technique requires iso-parametric coils to avoid interception of the longitudinal field component. The compensation of the main signal cannot be done with the classical arrangement of search coils at different radii, because no easy scaling law exists. A new design of an iso-perimetric induction coil has been found. Research limitations/implications In the literature, it is stated that the pseudo-multipoles can be extracted from field computations or measurements. While this is true for computations, the author shows that the measurement of the field harmonics must be done with iso-parametric coils because otherwise the leading term in the Fourier–Bessel series cannot be extracted. Practical implications The author has now established the theory behind a number of field transducers, such as the moving fluxmeter, the rotational coil scanner and the solenoidal field transducer. Originality/value This paper brought together the known theory of the orthogonal expansion method with the methods and tools for magnetic field measurements to establish a field description in accelerator magnets.

show abstract

“…The system, mounted on a rail and equipped with a linear encoder, is shown in Figure 2. The metrological characterization of the system was published in Arpaia et al (2015a).…”

Section: 1mentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Rotating- and translating-coil magnetometers for extracting pseudo-multipoles in accelerator magnets

Russenschuck

2017

COMPEL

View full text Add to dashboard Cite

show abstract

“…The most common case is the rotating-coil measurement of a static field, carried out during the acceptance tests. In this case, correction of integrator drift is facilitated by the very short integration times, typically one second or less, and by the periodicity of the measured flux as a function of the coil rotation angle [7]. Often the magnets are operated with fast magnetic cycles, so that measurements with a fixed induction coil are useful to capture dynamic effects.…”

Section: Introductionmentioning

confidence: 99%

Integrator Drift Compensation of Magnetic Flux Transducers by Feed-Forward Correction

Amodeo

Arpaïa

Buzio

2019

Sensors

View full text Add to dashboard Cite

Integrator drift is a problem strongly felt in different measurement fields, often detrimental even for short-term applications. An analytical method for modelling and feed-forward correcting drift in magnetic flux measurements was developed analytically and tested experimentally. A case study is reported on the proof of principle as a novel kind of quasi-DC field marker of the 5-ppm Nuclear Magnetic Resonance (NMR) transducer Metrolab PT2026, applied to the Extra Low ENergy Antiproton (ELENA) ring and the Proton Synchrotron Booster (PSB) at CERN. In some particle accelerators, such as in ELENA, the resulting feed-forward correction guarantees 1 µT field stability over 120-s long magnetic cycle on a plateau of 50 mT, reducing by three orders of magnitude the field error caused by the integrator drift with respect to the state of the art.

show abstract

“…The magnetic measurement section within the magnet group of CERN's technology department is responsible for the qualification of all superconducting and normal conducting magnets in CERN's accelerator complex. To supplement the long rotating-coil magnetometers and stretched-wire systems (the section's workhorses for magnetic measurements) we have recently developed moving induction-coil arrays, axial and transversal rotating-coil scanners [1], and inductioncoil transducers for solenoidal magnets. Applications of these tools require, however, a sophisticated post-processing step based on the regularity conditions of electromagnetic fields.…”

Section: Introductionmentioning

confidence: 99%

“…Developing these signals into Fourier series results in convoluted functions of the spacial flux distribution, because strictly speaking, point-like measurements of the magnetic flux density are not possible. 1 Before such signals can be used as boundary data for harmonic analysis or boundary-element methods (BEM), a deconvolution is required.…”

Section: Introductionmentioning

confidence: 99%

Challenges in extracting pseudo-multipoles from magnetic measurements

Russenschuck

Caiafa

Fiscarelli

et al. 2019

Int. J. Mod. Phys. A

Self Cite

View full text Add to dashboard Cite

Extracting the coefficients of Fourier-Bessel series, known as pseudo-multipoles or generalized gradients, from magnetic measurements of accelerator magnets involves technical and mathematical challenges. First, a novel design of a short, rotating-coil magnetometer is required that does not intercept any axial field component of the magnet. Moreover, displacing short magnetometers, step-by-step along the magnet axis, yields a convolution of the local multipole field errors and the sensitivity (test function) of the induction coil. The deconvolution must then content with the low signal-to-noise ratio of the measurands, which are integrated voltages corresponding to spatial flux distributions. Finally, the compensation schemes, as implemented on long coils used for measuring the integrated field harmonics, cannot be applied to short magnetometers. All this requires careful design of experiment to derive the optimal length of the induction coil, the step size of the scan, and the highest order of pseudo-multipoles in the field reconstruction. This paper presents the theory of the measurement method, the data acquisition and deconvolution, and the design and production of a saddle-shaped, rotating-coil magnetometer.

show abstract

A rotating coil transducer for magnetic field mapping

Cited by 5 publications

References 25 publications

Rotating- and translating-coil magnetometers for extracting pseudo-multipoles in accelerator magnets

Rotating- and translating-coil magnetometers for extracting pseudo-multipoles in accelerator magnets

Integrator Drift Compensation of Magnetic Flux Transducers by Feed-Forward Correction

Challenges in extracting pseudo-multipoles from magnetic measurements

Contact Info

Product

Resources

About