Twin rotating coils for cold magnetic measurements of 15 m long LHC dipoles

Billan, J.; Bottura, L.; Buzio, Marco; D'Angelo, G.; Deferne, G.; Dunkel, O.; Legrand, P.; Rijllart, A.; Siemko, A.; Sievers, P.; Schloss, S.; Walckiers, L.

doi:10.1109/77.828506

Cited by 52 publications

(57 citation statements)

References 5 publications

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“…where , is the value of the k-th undesired harmonic either normal (b k ) or skew (a k ) (2), measured synchronously by the same encoder trigger source by means of n series of m(q) harmonic coils (referred as n "supersegments"), and where (L pq +bs) is the length of the p-th harmonic coil segment of the q-th supersegment of the measuring shaft, with bs the blank space between segments [21].…”

Section: A Analytical Formulationmentioning

confidence: 99%

“…1 is the equipment for harmonic measurements of coils [21]. A test station with the main aim of improving the bandwidth was developed specifically for measuring pulsed magnetic fields.…”

Section: The Measurement Systemmentioning

confidence: 99%

“…The ratio between the bending strength of the main dipole magnets and the focusing strength of the quadrupole must be controlled within 15 ppm in order to limit tune changes to below 10 -2 during the whole beam cycle. Measurement systems existing at the time of the LHC construction are not suitable, due mainly a too low resolution, either in time domain [21] (harmonic coil techniques), or in space domain [22] (Hall probe detectors).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Active compensation of field errors within ±2ppm in superconducting magnets

Arpaïa

Fiscarelli

Montenero

et al. 2011

Nuclear Instruments and Methods in Physics Research Section A:

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A system for the active compensation of magnetic field errors within ±2 ppm relative to the main field in superconducting magnets is proposed. A high-performance rotating coils system is exploited in order to combine high time resolution and integral field measurements. The compensation is based on an enhanced characterization of the corrector magnets and the measured field: this allows the system to be used as off-line reference in accelerator facilities. As an experimental case study, the measurement system and the procedure for compensating field errors of dipole magnets of the Large Hadron Collider at the European Organization for Nuclear Research (CERN) are illustrated. Published in Nuclear Instruments and Methods in Physics Research A 2011Geneva, Switzerland CERN-ATS 2011-009

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Section: A Analytical Formulationmentioning

confidence: 99%

“…1 is the equipment for harmonic measurements of coils [21]. A test station with the main aim of improving the bandwidth was developed specifically for measuring pulsed magnetic fields.…”

Section: The Measurement Systemmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Active compensation of field errors within ±2ppm in superconducting magnets

Arpaïa

Fiscarelli

Montenero

et al. 2011

Nuclear Instruments and Methods in Physics Research Section A:

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“…Field quality measurements at cold were performed using rotating coil based systems [15] and cross-checked with Single Stretched Wire measurements [16] for the transfer function. This combination guarantees for the main field an uncertainty of 5 units and 1 unit for the reproducibility.…”

Section: Test Procedures and Measurementsmentioning

confidence: 99%

Magnetic Performance of the Main Superconducting Magnets for the LHC

Sanfilippo

Sammut

Bottura

et al. 2008

IEEE Trans. Appl. Supercond.

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Abstract-The field strength and homogeneity of all the LHC superconducting magnets were measured as a part of the production control and qualification process that has taken place during the past four years. In addition to field measurements at room temperature performed on the integral of the production, a significant part of the magnets has been subjected to extensive magnetic measurements at cold. The measurements at cryogenic temperatures, generally performed up to excitation currents of 12 kA corresponding to the ultimate LHC energy of 7.6 TeV, were mainly based on static and dynamic field integral and harmonic measurements. This allowed us to study in detail the DC effects from persistent current magnetization and long-term decay during constant current excitation. These effects are all expected to be of relevance for the field setting and error compensation in the LHC. This paper reports the main results obtained during these tests executed at operating conditions. The integrated field quality is discussed in terms of distribution (average and spread) of the field strength and low-order harmonics as obtained for all the main ring magnet families (dipoles, main and matching quadrupoles). The dependence of field quality on coil geometry, magnet and cable manufacturer is analyzed. A projection of the field quality expected for the critical components in the machine is presented.

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“…There are three main systems available at CERN to measure the integrated gradient for the cold tests of the LHC quadrupoles: the Single Stretched Wire (SSW) [2], the Automated Scanner [3] and the Twin Rotating Coils system [4]. The first is based on the moving stretched wire technique whereas the last two are based on rotating coil technique.…”

Section: Introductionmentioning

confidence: 99%

Focusing Strength Measurements of the Main Quadrupoles for the LHC

Smirnov

Bottura

Calvi

et al. 2006

IEEE Trans. Appl. Supercond.

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More than 1100 quadrupole magnets of different types are needed for the Large Hadron Collider (LHC) which is in the construction stage at CERN. The most challenging parameter to measure on these quadrupoles is the integrated gradient (Gdl). An absolute accuracy of 0.1% is needed to control the beta beating. In this paper we briefly describe the whole set of equipment used for Gdl measurements: Automated Scanner system, Single Stretched Wire system and Twin Coils system, concentrating mostly on their absolute accuracies. Most of the possible inherent effects that can introduce systematic errors are discussed along with their preventive methods. In the frame of this qualification some of the magnets were tested with two systems. The results of the intersystem cross-calibrations are presented. In addition, the qualification of the measurement system used at the magnet manufacturer's is based on results of more than 40 quadrupole assemblies tested in cold conditions at CERN and in warm conditions at the vendor site.

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Twin rotating coils for cold magnetic measurements of 15 m long LHC dipoles

Abstract: Abslruct

Cited by 52 publications

References 5 publications

Active compensation of field errors within ±2ppm in superconducting magnets

Active compensation of field errors within ±2ppm in superconducting magnets

Magnetic Performance of the Main Superconducting Magnets for the LHC

Focusing Strength Measurements of the Main Quadrupoles for the LHC

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