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

Magnetic properties of a nanocrystalline material for current derivative sensors of magnets protection systems

Nanocrystalline materials are becoming ever more broadly used in transformer-based transducers due to their low losses, high relative permeability and high saturation flux density. In this paper, the magnetic characterization of one of these materials is presented by highlighting its influence on the performance of a current derivative sensor. This sensor was recently prototyped at CERN in the framework of the consolidation activity on the quench protection of superconducting magnets for the high-luminosity upgrade of the Large Hadron Collider. The performance is analyzed in terms of linearity and dynamic response

A Static-Sample Magnetometer for Characterizing Weak Magnetic Materials

In this paper, a static-sample magnetometer is presented to measure the relative permeability of weakly magnetic materials. The method consists of scanning the magnetic field inside a dipole magnet by using an NMR teslameter to measure the perturbation of a test specimen on the externally applied field. Then, an inverse problem is used to compute the specimen's relative permeability. As a case study, the measurement of three different materials with different shapes and dimensions is carried out. The method was validated by measuring the same material by a vibrating sample magnetometry as proposed by the standard ASTM A342/A342M-14. The Monte Carlo evaluated expanded measurement uncertainty of the relative permeability is about 10 −4 for all the cases, with a level of confidence of 95 %

Clinical impact of COVID-19 on tuberculosis

: During COVID-19 pandemic, a lot of diseases suffered from a limited access to health care services, owing to the use of resources, both technical and financial, mainly directed towards such a dramatic outbreak. Among these, tuberculosis (TB) has been one of the most penalized, with a huge delay both in diagnosis and in start of treatment, with a consequential dramatic increase in morbidity and mortality. COVID-19 and tuberculosis share similar common pathogenetic pathways, and both diseases affect primarily the lungs. About the impact of TB on COVID-19 severity and mortality, data are unclear and literature reports are often conflicting. Certainly, considering the management of coinfected patients, there are pharmacokinetic interactions between several drugs used for the therapy of SARS-CoV-2 infection and the treatment of TB

A Superconducting Permeameter for Characterizing Soft Magnetic Materials at High Fields

Asuperconductingpermeameterisproposedtocharacterizethemagneticpropertiesofhigh-energysuperconducting magnet yokes at their operating temperatureand saturation level. The main problem of superconductingcoils, an undesired quench, was faced by specific protectionsimulations, which has led to a self-protected system. Thesuperconducting permeameter was used to perform the magneticcharacterization of ARMCO Pure Iron, the material for the newHigh-Luminosity Large Hadron Collider (HL-LHC) supercon-ducting magnet yokes, which was performed at the cryogenictemperature of 4.2 K and a saturation level of nearly 3 T.Two case studies based on the new HL-LHC superconductingquadrupole and dipole magnets highlight the impact of themagnetic properties of the yoke on the performance of thesuperconducting magnets, showing that the common assumptionthat heavily saturated steels with similar chemical compositionbehave precisely the same way has been proven wrong

Wave monitoring using buoy based - wireless sensor nodes

Peer Reviewe

On the use of fluxmetric methods for characterizing feebly magnetic materials

The problems related to the use of a split-coil permeameter for measuring the magnetic properties of materials with low relative permeability are faced. In particular, a challenging problem arises from the series production of steel tapes: magnetic and paramagnetic materials, in fact, exhibit different magnetic properties according to the production process (i.e. annealing and cold work). Consequently, samples of this material differently treated have to be characterized in order to find the optimal cold work and annealing able to minimize raising of magnetism. In this paper, fluxmetric methods, widely employed for magnets testing, are extended to the characterization of feebly magnetic materials. A case study for the series production of steel tapes about co-wound 1.430 stainless steel tapes, the material used for the quench detection in ITER TF coils [1], is presented