Measuring the magnetic axis alignment during solenoids working

A method for monitoring the misalignment of the magnetic axis in solenoids is proposed. This method requires only a few measurements of the magnetic field at fixed positions inside the magnet aperture, and thus overcomes the main drawback of sturdy moving mechanics of other Hall sensor-based methods. Conversely to state-of-the-art axis determination, the proposed method can be applied also during magnet operations, when the axis region and almost the whole remaining magnet aperture are not accessible. Moreover, only a few measurements of the magnetic field at fixed positions inside the magnet aperture are required: thus a slow process such as the mapping of the whole aperture of a magnet by means of moving stages is not necessary. The mathematical formulation of the method is explained, and a case study on a model of a multi–layer solenoid is presented. For this case study, the uncertainty is assessed and the optimal placement of the Hall transducers is derived

Magnetic material characterization and magnet axis displacement measurement for particle accelerators

Bending and focusing magnets, both normal- or super-conducting, are crucial elements for the performance of any particle accelerator. Their design requirements are always more tighten regarding components’ misalignment and magnetic properties. This dissertation proposes new solutions for characterizing magnetic materials and monitoring solenoids’ magnetic axis misalignments. A superconducting permeameter is designed to characterize the new-generation superconducting magnet yokes at their operational temperature and saturation level. As proof of principle, the magnetic characterization of ARMCO® Pure Iron was performed at the cryogenic temperature of 4.2 K and a saturation level of nearly 3 T. A case study based on the new HL-LHC superconducting magnets quantifies the impact of the magnetic properties of the yoke on the performances of the superconducting magnets. A flux-metric based method is proposed to identify the relative magnetic permeability of weakly magnetic materials. As proof of principle, the magnetic properties of the ITER TF coils quench detection stainless steel are analyzed. This method is not suitable to test materials with a relative permeability lower than 1.1. Hence, a measurement system based on a new magneto-metric method is conceived and validated employing a standard reference sample. The methods proposed in this thesis are currently employed at CERN’s magnetic laboratory to face an increasing number of requests concerning not only the magnetic characterization of materials for magnets but also for shielding systems and compatibility of various components with high magnetic fields. In this thesis, the results of the evaluation of ARMCO® Pure Iron as the yoke of the new LHC superconducting magnets and CRYOPHY as the magnetic shield for the cryomodule prototypes of HL-LHC Crab Cavities are reported. Finally, a new Hall-sensor method is conceived and implemented for monitoring the coils alignment in multi-coil magnets, directly during their operation in particle accelerators. The proposed method is suitable even for those cases when almost the whole magnet aperture is not accessible. Requiring only a few measurements of the magnetic field at fixed positions inside the magnet aperture, the method overcomes the main drawback of the other Hall sensor-based methods which is having to deal with sturdy mechanics of the moving stages. The method is validated numerically on a challenging case study related to the Solenoid B of the project ELI-NP

emiT: an apparatus to test time reversal invariance in polarized neutron decay

We describe an apparatus used to measure the triple-correlation term (\D \hat{\sigma}_n\cdot p_e\times p_\nu) in the beta-decay of polarized neutrons. The \D-coefficient is sensitive to possible violations of time reversal invariance. The detector has an octagonal symmetry that optimizes electron-proton coincidence rates and reduces systematic effects. A beam of longitudinally polarized cold neutrons passes through the detector chamber, where a small fraction beta-decay. The final-state protons are accelerated and focused onto arrays of cooled semiconductor diodes, while the coincident electrons are detected using panels of plastic scintillator. Details regarding the design and performance of the proton detectors, beta detectors and the electronics used in the data collection system are presented. The neutron beam characteristics, the spin-transport magnetic fields, and polarization measurements are also described.Comment: 15 pages, 13 figure

The Effect Of Magnetic Bearing On The Vibration And Friction Of A Wind Turbine

Demands for sustainable energy have resulted in increased interest in wind turbines. Thus, despite widespread economic difficulties, global installed wind power increased by over 20% in 2011 alone. Recently, magnetic bearing technology has been proposed to improve wind turbine performance by mitigating vibration and reducing frictional losses. While magnetic bearing has been shown to reduce friction in other applications, little data has been presented to establish its effect on vibration and friction in wind turbines. Accordingly, this study provides a functional method for experimentally evaluating the effect of a magnetic bearing on the vibration and efficiency characteristics of a wind turbine, along with associated results and conclusions. The magnetic bearing under examination is a passive, concentric ring design. Vibration levels, dominant frequency components, and efficiency results are reported for the bearing as tested in two systems: a precision test fixture, and a small commercially available wind turbine. Data is also presented for a geometrically equivalent ball bearing, providing a benchmark for the magnetic bearing’s performance. The magnetic bearing is conclusively shown to reduce frictional losses as predicted by the original hypothesis. However, while reducing vibration in the precision test fixture, the magnetic bearing demonstrates increased vibration in the small wind turbine. This is explained in terms of the stiffness and damping of the passive test bearing. Thus, magnetic bearing technology promises to improve wind turbine performance, provided that application specific stiffness and damping characteristics are considered in the bearing design

Technical Design Report for the PANDA Solenoid and Dipole Spectrometer Magnets

This document is the Technical Design Report covering the two large spectrometer magnets of the PANDA detector set-up. It shows the conceptual design of the magnets and their anticipated performance. It precedes the tender and procurement of the magnets and, hence, is subject to possible modifications arising during this process.Comment: 10 pages, 14MB, accepted by FAIR STI in May 2009, editors: Inti Lehmann (chair), Andrea Bersani, Yuri Lobanov, Jost Luehning, Jerzy Smyrski, Technical Coordiantor: Lars Schmitt, Bernd Lewandowski (deputy), Spokespersons: Ulrich Wiedner, Paola Gianotti (deputy

Technical Design Report for the PANDA Solenoid and Dipole Spectrometer Magnets

This document is the Technical Design Report covering the two large spectrometer magnets of the PANDA detector set-up. It shows the conceptual design of the magnets and their anticipated performance. It precedes the tender and procurement of the magnets and, hence, is subject to possible modifications arising during this process

Modeling of the response function and measurement of transmission properties of the KATRIN experiment

This thesis was performed in the context of the Karlsruhe Tritium Neutrino (KATRIN) experiment which aims to determine the effective mass of the electron antineutrino with an unprecedented sensitivity of 200 meV/c^2 (90% C.L.). The main goals of this thesis were to perform large scale Monte Carlo simulations of signal electrons to model the properties of the response function of the experiment with great precision as well as to determine the transmission properties of the main spectrometer

Determination of Electromagnetic Fields and Tritium Column Density for Neutrino Mass Analysis with KATRIN

Das KArlsruher TRitium Neutrino (KATRIN) Experiment hat als Ziel die effektive Elektron-Antineutrinomasse modellunabhängig mit einer Sensitivität von 0.2 eV (90 % C.L.) zu bestimmen, indem das Tritium $\beta$-Zerfallspektrum nahe dem kinematischen Endpunkt untersucht wird. Um dieses Ziel zu erreichen ist eine genaue Charakterisierung der KATRIN Antwortfunktion für Signalelektronen erforderlich. In der vorliegenden Arbeit werden zwei wichtige Komponenten der Antwortfunktion mit großer Genauigkeit untersucht, nämlich die elektromagnetischen Felder im KATRIN Aufbau sowie die Gasmenge in der Tritiumquelle

Intracorporeal anchoring and guiding system with permanent magnet force modulation

Magnetic manipulation of objects within the body is a growing field of research since the second half of the last century. Therapeutic and diagnostic capabilities offered by such technology are extended with the clinical need to make procedures less invasive and traumatic for the patients. Ophthalmologists were among the first to explore magnetic manipulation for removing iron fragments from the interior of the eye. Subsequently, the intubation devices were developed for extracting foreign objects from the body. The first case of magnetic guidance is an intravascular catheter magnetically guided by large external magnets in the 1950s. Half a century later, magnetic actuation of medical devices has led to many developments growing in complexity, such as wireless endoscopic capsule for exploring the gastrointestinal tract; intraocular microrobots of sub-millimitric size per- forming delicate tasks; internal magnetic laparoscopic instruments magnetically coupled through the abdominal wall without the need of additional incisions; or enormous systems for remote magnetic steering of catheters in cardiovascular or neurological procedures. Technically, magnetic guidance requires variable, reshapable or steerable magnetic fields and therefore is generally associated with large magnetic arrangements of coils or perma- nent magnets surrounding the patient; while magnetic anchoring is achievable by external permanent magnets of adequate size placed or dragged manually on the surface of the body. In this thesis work, we propose a novel type of magnetic guidance. Instead of having the guiding part external to the body, we propose to perform the guidance locally, on- site, by having the guiding part within the body in close vicinity of the element to be guided. Although the separation distance between the guiding and guided member is decreased, the required magnetic field to be generated is still significant with regards to the size of the system. Moreover, the magnetic attractions force should be adjusted in order to provide a robust guidance over variable and dynamic anatomical conditions. Electromagnets are an ideal solution by their ability to control the strength, polarity and shape of the generated magnetic field. However, obtaining a substantial magnetic field strength becomes challenging in the millimetric scale. Rare-earth magnets produce strong magnetic fields and become interesting when size is limited. But, they produce a constant field and the resulting attractive forces are strongly depending on the distance, which can be a safety issue. To overcome these hurdles, we present a proof-of-concept of intracorporeal force mod- ulation with steerable permanent magnets. We demonstrate through several examples that the magnetic forces applied to the guided element can be modulated by combining permanent magnets together or with other ferromagnetic materials. A first prototype of force modulator is produced, characterized and tested in vitro. We analyze the behavior of this “magnetotractive” system of guidance through two operating modes, namely passive and active guidance modes. While the passive guidance mode uses static magnetic fields, the active guidance mode allows the variation of the magnetic field during the guidance. Operating at static magnetic field implies that the coupling force within the system depends on the tissue thickness and irregularities. As the coupling force decreases approximately as the square of the distance, levels of coupling force could rapidly change during the guidance. Therefore, having the capability of adjusting the coupling force provides flexibility of the method. We demonstrate that active control can be achieved by a combination of several movable permanent magnets. This provides smoother guidance and superior robustness in comparison with the passive mode. On the guided element, we empirically identify the parameters representing the most significant effect on friction during the guidance. These findings could be very helpful in the design of magnetic guidance systems. Finally, we show that magnetic attractive forces applied on the guided element could be adjusted with permanent magnet arrangements. This solution not only offers larger amplitude of force with regards to its size, but the range of modulation is significant in comparison with electromagnets. In addition, we demonstrate in vitro that intracorporeal magnetic guidance with steerable permanent magnets is feasible over variable and irregular tissue thickness. Therefore, this novel type of guidance has the potential to facilitate for example the treatment of cardiac arrhythmias