A LARGE BORE QUADRUPOLE MAGNET FOR CALIBRATION OF ROTATING COILS (original) (raw)
Related papers
Small-Diameter Rotating Coils for Field Quality Measurements in Quadrupole Magnets
2014
Two rotating coil shafts with a challenging small diameter of 8 and 19 mm, originally developed at CERN for the measurement of linear accelerator magnets, have been used to quantify the magnetic field strength, the harmonic content and the field direction of series quadrupoles for the Swiss Free Electron Laser in construction at the Paul Scherrer Institute. In this paper, we describe the design and construction of these coils, the procedure used for their calibration, and the results obtained on the magnets tested so far. We focus especially on the manufacturing and calibration difficulties related to the very small diameter of these coils, which makes it challenging to obtain relative errors at the level of a few 10 -4 as it is commonly required by accelerator beam optics. The last part of the paper is dedicated to a selection of measurement results obtained on Swiss Free Electron Laser quadrupoles to illustrate the performance of the two types of coils on series measurements.
Rotating-Coil Measurement System for Small-Bore-Diameter Magnet Characterization
Sensors
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 compon...
Measurement, 2016
A method is proposed for calibrating the radius of a rotating coil sensor by relaxing the metrological constraints on alignment and field errors of the reference quadrupole. A coil radius calibration considering a roll-angle misalignment of the measurement bench, the magnet, and the motor-drive unit is analyzed. Then, the error arising from higher-order harmonic field imperfections in the reference quadrupole is assessed. The method is validated by numerical field computation for both the higher-order harmonic errors and the roll-angle misalignment. Finally, an experimental proof-of-principle demonstration is carried out in a calibration magnet with sextupole harmonic.
In situ calibration of rotating sensor coils for magnet testing
Review of Scientific Instruments, 2012
An in situ procedure for calibrating equivalent magnetic area and rotation radius of rotating coils is proposed for testing accelerator magnets shorter than the measuring coil. The procedure exploits measurements of magnetic field and mechanical displacement inside a reference quadrupole magnet. In a quadrupole field, an offset between the magnet and coil rotation axes gives rise to a dipole component in the field series expansion. The measurements of the focusing strength, the displacement, and the resulting dipole term allow the equivalent area and radius of the coil to be determined analytically. The procedure improves the accuracy of coils with large geometrical irregularities in the winding. This is essential for short magnets where the coil dimensions constrain the measurement accuracy.
DESIGN AND FABRICATION OF A ROTATING COIL MAGNETIC MEASUREMENT SYSTEM
2001
A rotating coil magnetic measurement system has been built at SSRC to measure the quadrupole and sextupole magnet prototypes of SSRF. The system consists of several rotating coils designed for different magnets and a control system. The coils are designed to have nearly zero sensitivity to the fundamental signals in bucked configurations. The control system is designed to be versatile, modular, expandable, maintainable, quick and easily reconfigurable in both hardware and software. This system can provide 0.01% precision.
Precision Analysis and Design of Rotating Coil Magnetic Measurements System
Applied Sciences, 2020
This research presents the design and construction of measuring instruments for a dipole magnetic field using a rotating coil technique. This technique is a closed-loop speed-control system where a Proportional-Integral (PI) controller works together with the intensity measurement of the magnetic field through the rotating coil. It was used to analyze the impact on the accuracy of the electromagnetic at speed ranges of 60, 90, and 120 rpm. The error estimation in the measurement of the normal dipole and skew dipole magnet caused by the steady-state error of the speed control system and the rotational search coil in whirling motion are demonstrated. Rotating unbalance, shaft coupling, and misalignment from its setup disturbed the performance of the speed control system as a nonlinear system.
A polyvalent harmonic coil testing method for small-aperture magnets
Review of Scientific Instruments, 2012
A new compact, high sensitivity neutron imaging system Rev. Sci. Instrum. 83, 10E131 (2012) Generation of a beam of fast electrons by tightly focusing a radially polarized ultrashort laser pulse Appl. Phys. Lett. 101, 041105 The various manifestations of collisionless dissipation in wave propagation Phys. Plasmas 19, 063110 Experimental investigation on focusing characteristics of a He-Ne laser using circular Fresnel zone plate for highprecision alignment of linear accelerators Rev. Sci. Instrum. 83, 053301 (2012) Frequency control in the process of a multicell superconducting cavity production Rev. Sci. Instrum. 83, 043304 Additional information on Rev. Sci. Instrum.
An in-situ procedure for calibrating the equivalent radius and width of the coil transducer in rotating mode measurements for magnetic field quality analysis is proposed. The standard calibration procedure is not suitable when the coil is longer than the magnet under test, because an average value of the radius and of the width along the length as a whole is obtained. This problem increases for small coils used in small-aperture magnets, such as quadrupoles of new-generation linear accelerators. In the paper, the problem of the coil parameter calibration is highlighted and then the proposed calibration method and the corresponding measurement station are illustrated. Experimental results of a case study on the magnet series of the new linear particle accelerator LINAC4, designed to intensify the proton flux currently available in the accelerator chain at the European Organization for Nuclear Research (CERN), are reported.
Calibration of the 3-D Coil System's Orthogonality
IEEE Transactions on Magnetics, 2000
Two methods were tested for calibration procedures of the 3-D coil system which is used as a source part of the magnetic tracker. Precise magnetometer's positions with respect to the coil system were used for determining of the nonorthogonality of the coil system as well as for determining of the magnetic moment. The needed number of the reference positions was measured to calculate six unknown calibrated parameters. In comparison, the 3-D coils system was also calibrated with a method which employs the orthogonal homogenous ac field generated in Helmholtz coils. The misalignment of up to two degrees was discovered.
New small diameter rotating coil shaft for characterizing new generation of multipolar magnets
Journal of Physics: Conference Series, 2019
The proliferation of ultimate-light source facilities around the world has yielded the need of accurate characterization of small gap magnets. This also applies to multipolar magnets. Clearance diameters down to 10 mm for quadrupoles and sextupoles become to be used and need to be accurately measured. At these small gaps, the high order multipoles influence on electron beam dynamics is high, and it should be well characterized in order to guarantee a feasible operation of the accelerator. To face this challenge, ALBA magnetic measurement laboratory has developed a new rotating coil shaft with a diameter of 10 mm able to be introduced inside narrow-gap multipolar magnets. In this paper we present the design as well as the manufacturing of such a device.