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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.

Understanding the magnetic properties of materials used in accelerator components is becoming more and more important. For example, in the upcoming LHC upgrade at CERN, the increasing luminosity will boost the radiation dose received by the accelerator magnet's coil and consequently decrease its lifespan. Hence, a radiation shield with relative permeability less than 1.005 is required. The goal of this research is to design and validate a new method for characterizing weekly magnetic materials, suitable to be used in quality control of series production. The proposed method is based on inverse analysis approach coupled with a finite-element model. A material with unknown permeability is inserted in the air gap of a dipole magnet and the consequent perturbations of the dipole background flux density are measured. The magnetic permeability is then identified through gray-box inverse modelling, based on a finite-element approach. The results have been used to predict the magnetic impact of the radiation shield and develop further research on this subject., Proceedings of the 8th Int. Particle Accelerator Conf., IPAC2017, Copenhagen, Denmark

A superconducting permeameter is proposed to characterize the magnetic properties of high-energy superconducting magnet yokes at their operating temperature and saturation level. The main problem of superconducting coils, an undesired quench, was faced by specific protection simulations, which has led to a self-protected system. The superconducting permeameter was used to perform the magnetic characterization of ARMCO Pure Iron, the material for the new High-Luminosity Large Hadron Collider (HL-LHC) superconducting magnet yokes, which was performed at the cryogenic temperature of 4.2 K and a saturation level of nearly 3 T. Two case studies based on the new HL-LHC superconducting quadrupole and dipole magnets highlight the impact of the magnetic properties of the yoke on the performance of the superconducting magnets, showing that the common assumption that heavily saturated steels with similar chemical composition behave precisely the same way has been proven wrong.

In this paper, the importance of magnetic material measurements in the framework of the design of magnets for particle accelerator is discussed. In particular, five samples of different ferromagnetic materials are analyzed experimentally and compared with literature results. These materials have been (or will be) used for producing yokes for several normal-conductor magnets at CERN, such as REX-ISOLDE main dipole, ELENA dipole and quadrupole, and SESAME dipole. The comparison with literature shows several disagreements. The main one of them is analyzed in detail in a case study based on finite elements simulation of a quadrupole magnet installed in CERN. This analysis shows that a good knowledge of the yoke initial magnetization curve is important to guarantee a given level of magnet performance, especially concerning its field quality.

An easily accessible polyoxomolybdate–calix[4]arene hybrid 1 has been synthesized and applied as a heterogeneous catalyst in the sulfoxidation of thioethers to sulfoxides and to sulfones under strictly stoichiometric amounts of 30% H2O2 in CH3CN as the solvent. This study represents the first promising example of successful employment of calixarenes–polyoxometalate (POM) hybrid materials in the area of catalytic oxidations.