324,174 research outputs found
A magneto-mechanical model for rotating-coil magnetometers
Get PDFRotating-coil magnetometers are among the most common transducers for measuring local and integral magnetic fields of accelerator magnets. The measurement uncertainty strongly depends on the mechanical properties of the shafts, bearings, drive systems, and supports. This paper proposes an analytical mechanical model for rotating-coil magnetometers, which allows a sensitivity analysis of mechanical phenomena affecting magnetic measurements. Both static and dynamic effects are considered. The model is validated numerically with a finite element model, and experimentally on an operational device
Metrological characterisation of rotating-coil magnetometer systems
Get PDFRotating-coil magnetometers are among the most common and most accurate transducers for measuring the integral magnetic-field harmonics in accelerator magnets. The measurement uncertainty depends on the mechanical properties of the shafts, bearings, drive systems, and supports. Therefore, rotating coils require a careful analysis of the mechanical phenomena (static and dynamic) affecting the measurements, both in the design and in operation phases. The design phase involves the estimation of worst-case scenarios in terms of mechanical disturbances, while the operation phase reveals the actual mechanical characteristics of the system. In previous publications, we focused on modelling the rotating-coil mechanics for the design of novel devices. In this paper, we characterise a complete system in operation. First, the mechanical model is employed for estimating the forces arising during shaft rotation. Then, the effect of the estimated disturbances is evaluated in a simulated measurement. This measurement is then performed in the laboratory and the two results are compared. In order to characterise the robustness of the system against mechanical vibrations, different revolution speeds are evaluated. This work thus presents a complete procedure for characterising a rotating-coil magnetometer system
Design of Energy-Saving MgB_\rm{2} Ramped Superconducting Magnets for Particle Beam Lines [Design of Energy-Saving MgB2 Ramped Superconducting Magnets for Particle Beam Lines = Design of Energy-Saving MgB]
No full textLarge accelerator facilities in the medium- and high-energy particle range can consume a significant amount of energy to power the resistive magnets in the beamlines. Depending on the magnet duty cycle, new magnet designs based on superconducting configurations have become increasingly attractive as possible alternatives to energy-intensive resistive solutions. High-temperature superconductor coils made in BCO (rare earth copper oxide) and MgB based cables can be used for both static and ramped magnets thanks to their high energy margin due to the large critical temperature. The University of Milan and INFN-Milano LASA lab. research team are currently working on developing superconducting magnet designs to replace the conventional resistive coils without modifications of the iron yoke of the normal-conducting solution. To highlight the potential of these superconducting materials, we present an estimation of the energy consumption reduction achieved in a MgB superferric dipole ramped magnet case study for the CNAO accelerator complex. Two design iterations, optimized at 10 K and 20 K, are compared with the resistive design demonstrating the benefit on total consumed energy and cost of this type of superconducting magnet solutions for large-scale research facilities
Data-driven simulation of transient fields in air–coil magnets for accelerators
No full textTime-varying fields in fast-ramping magnets for accelerators are difficult to compute in the range of accuracy required for magnet operation. This is due to the complexity of the dynamic phenomena such as hysteresis and 3D eddy currents. On the other hand, magnetic measurements that intercept all these physical phenomena are often limited to a subset of excitation cycles and restricted spatial domains. The measurement results are therefore difficult to extrapolate without a validated physical model of the device. This paper proposes measurement-updated field simulations to characterize dynamic effects in accelerator magnets. The main idea is to construct a reduced-order model, whose variables are retrievable from measurements by means of a state estimator, and to update the model by minimizing the error between simulations and measurements. The proposed method is applied to a linear, time-transient electromagnetic-field problem of an air–coil corrector magnet with aluminium collars. The proposed method is a first step towards a hybrid twin of an accelerator magnet
A mechanical analysis of rotating-coil magnetometers
No full textRotating-coil magnetometers are among the most common and most accurate transducers for measuring the integral magnetic-field harmonics in accelerator magnets. The measurement uncertainty depends on the mechanical properties of the shafts, bearings, drive systems, and supports. In this paper we study the mechanical phenomena (static and dynamic) affecting rotating-coil measurements and propose analysis and diagnostic methods for improving the instrument in terms of material choice and geometrical design. The propagation of uncertainty is investigated on the measured quantities (induced voltages, integrated and developed into a Fourier series, the coefficients of which are know as field harmonics). This results in a consistent framework for the design of a measurement bench for rotating-coil magnetometers. The paper also presents the design of a complete system, including displacement stages, supports, rotating coils, and an angular position system
Induction-Coil Measurement System for Normal- and Superconducting Solenoids
No full textThe magnetic measurement of solenoids relies on different methods to characterize the field quality and locate the magnetic axis. Usually, Hall mappers and stretched-wire systems are used for these tasks. This paper presents an alternative, fluxmetric method to measure the radial field dependence and the magnetic axis with a single instrument. The solenoidal-field transducer is based on a disc-shaped induction-coil array with concentric coils and 90 deg. arc segments mounted on a translation stage. This allows to sample the magnet along its axis and to extract both the longitudinal and transversal field components. The design, development, and validation of the new instrument are described. The induction coil, which is the core of this instrument, is fabricated in printed-circuit board technology, which has become the new standard for these applications. Results of recent measurements of a normal-conducting solenoid magnet are given
A mechanical analysis of rotating-coil magnetometers
No full textRotating-coil magnetometers are among the most common and most accurate transducers for measuring the integral magnetic-field harmonics in accelerator magnets. The measurement uncertainty depends on the mechanical properties of the shafts, bearings, drive systems, and supports. In this paper we study the mechanical phenomena (static and dynamic) affect-
ing rotating-coil measurements and propose analysis and diagnostic methods for improving the instrument in terms of material choice and geometrical design.
The propagation of uncertainty is investigated on the measured quantities (induced voltages, integrated and developed into a Fourier series, the coefficients of which are know as field harmonics). This results in a consistent framework for the design of a measurement
bench for rotating-coil magnetometers. The paper also presents the design of a complete system, including displacement stages, supports, rotating coils, and an angular position system
Data-driven simulation of transient fields in air–coil magnets for accelerators
No full textTime-varying fields in fast-ramping magnets for accelerators are difficult to compute in the range of accuracy required for magnet operation. This is due to the complexity of the dynamic phenomena such as hysteresis and 3D eddy currents. On the other hand, magnetic measurements that intercept all these physical phenomena are often limited to a subset of excitation cycles and restricted spatial domains. The measurement results are therefore difficult to extrapolate without a validated physical model of the device. This paper proposes measurement-updated field simulations to characterize dynamic effects in accelerator magnets. The main idea is to construct a reduced-order model, whose variables are retrievable from measurements by means of a state estimator, and to update the model by minimizing the error between simulations and measurements. The proposed method is applied to a linear, time-transient electromagnetic-field problem of an air–coil corrector magnet with aluminium collars. The proposed method is a first step towards a of an accelerator magnet
Data-driven modeling of nonlinear materials in normal-conducting magnets
No full textAccurate numerical modeling of normal-conducting accelerator magnets requires a reliable characterization of the iron saturation and hysteresis as well as a precise knowledge of the magnet geometry as built. Computations of the field quality are not easily achieving the accuracy required by the accelerator operation, particularly for eddy-current effects in fast-ramping magnets. This paper proposes a (measurement) data-driven model for the nonlinear magnetization of normal-conducting magnets. The model adopts a volume integral formulation compatible with eddy-current simulations. A two-step updating procedure is applied. The first step is the fitting of material parameters directly in the magnet model. The second step is the updating of the magnetization by measurements of the integral field harmonics. The result is a full-order updated model that can be employed in static or dynamic simulations. Finally, the procedure is validated on an iron-dominated, normal-conducting magnet
Data-driven modeling of nonlinear materials in normal-conducting magnets
Get PDFAccurate numerical modeling of normal-conducting accelerator magnets requires a reliable characterization of the iron saturation and hysteresis as well as a precise knowledge of the magnet geometry as built. Computations of the field quality are not easily achieving the accuracy required by the accelerator operation, particularly for eddy-current effects in fast-ramping magnets. This paper proposes a (measurement) data-driven model for the nonlinear magnetization of normal-conducting magnets. The model adopts a volume integral formulation compatible with eddy-current simulations. A two-step updating procedure is applied. The first step is the fitting of material parameters directly in the magnet model. The second step is the updating of the magnetization by measurements of the integral field harmonics. The result is a full-order updated model that can be employed in static or dynamic simulations. Finally, the procedure is validated on an iron-dominated, normal-conducting magnet
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