Superconducting magnet | EPFL Graph Search

A superconducting magnet is an electromagnet made from coils of superconducting wire. They must be cooled to cryogenic temperatures during operation. In its superconducting state the wire has no electrical resistance and therefore can conduct much larger electric currents than ordinary wire, creating intense magnetic fields. Superconducting magnets can produce stronger magnetic fields than all but the strongest non-superconducting electromagnets, and large superconducting magnets can be cheaper to operate because no energy is dissipated as heat in the windings. They are used in MRI instruments in hospitals, and in scientific equipment such as NMR spectrometers, mass spectrometers, fusion reactors and particle accelerators. They are also used for levitation, guidance and propulsion in a magnetic levitation (maglev) railway system being constructed in Japan. Construction Cooling During operation, the magnet windings must be cooled below their critical temperature

Analysis of Quench Detection and Protection of a Nb3Sn CCT Technology Demonstrator Dipole for FCC

Jiani Gao

From 2016, Paul Scherrer Institut (PSI) started an activity related to developing design, construction and testing of the superconducting magnets. My thesis work is part of this activity and mainly concerns the design and construction of an innovative high-field superconducting magnet of the Canted-Cosine-Theta (CCT) type - a possible candidate for the Future Circular Collider (FCC) 16 T dipole magnet design. The unique mechanical structure intercepts the accumulated forces lowering the stress on the windings, constituting intrinsic stress management in the high-field Nb3Sn accelerator magnets. However, this structure also constitutes a barrier for heat to quickly propagate in case of a quench. To succeed in the CCT-type magnet design and construction, quench protection is a challenging task that requires a detailed investigation of the electrothermal behavior of this magnet. In this thesis, the potential detection and protection concepts are studied by the multiphysics simulations on a two-layer short model built at PSI and also in a subscale experiment. The 2D User-Defined Elements (UDEs) developed at Lawrence Berkeley National Laboratory (LBNL) in ANSYS Mechanical APDL, which support multi-dependence material properties and include the effect of inter-filament coupling currents, are adapted and used in the coupled electrothermal, electrodynamic, and electrical-circuits calculations for a two-layer CCT-type magnet with different protection methods, such as Coupling-Loss Induced Quench (CLIQ) and Energy-Extraction (EE) system. A first-of-a-kind CCT-type magnet protection study using UDEs is presented. The generic model method is validated through the test data of CCT4, a model magnet constructed at LBNL, protected by an energy-extraction system. The simulation predictions are the first steps of the conceptual design and feasibility validation of the construction of a fast and efficient quench protection system for CCT-type magnets to be operated in an accelerator. These calculations are to be compared to the experimental data in the near future on the PSI's first 1-m long two-layer CCT-type model magnet, CD1. Furthermore, these studies lay the ground for the four-layer CCT protection concepts for FCC.

EPFL2020

Beam-Machine Interaction Studies for the Phase II LHC Collimation System

Luisella Lari

Collimation is essential in a high Energy and Intensity hadron collider with SuperConducting magnets, like the LHC at CERN. To improve the cleaning efficiency and to reduce the LHC impedance budget in stable condition and at top Energy, additional 30 Phase II collimators are foreseen to be installed. The work of this PhD analyses the beam-machine interactions in the LHC Betatron Cleaning Insertions for its upgrade with the Phase II collimators. These studies aim at optimizing the collimation system layout from the machine protection point of view, considering different options for the Phase II collimator design and focusing on heating damage and activation problems. The outcomes of this PhD work have been used to support the Phase II design evolution and their prototype mechanical integration, and to point out possible critical points along the Betatron Cleaning Straight Section. Emphasis is on studying several configurations and material choices for nominal and failure scenarios.

EPFL2010

Analysis of a Novel Toroidal Configuration for Hadron Therapy Gantries

Enrico Felcini

Hadron therapy refers to a medical treatment that uses hadron beams (i.e. protons and ions) to deliver localized energy that suppresses cancerous cells, sparing the neighbouring healthy tissues from unwanted radiation. The major technical components of a hadron therapy centre are the particle accelerator (cyclotron, synchrotron, or linac) and the beam delivery system that controls, shapes and orients the particles towards the area to be treated. The beam delivery can consist of fixed transfer lines, or it can include a gantry, a transfer line that rotates around the patient and allows radiation from multiple directions. The present work investigates a new toroidal gantry for hadron therapy, named GaToroid. This novel gantry configuration allows the dose delivery from a discrete number of angles avoiding magnets as well as patient rotation. Compared to traditional gantries that require rotating magnets, this improvement is made possible by a toroidal magnet operating in steady-state. This design constitutes the ideal conditions for the use of superconductors to generate a significantly higher magnetic field compared to normal-conducting solutions, as well as to reduce the weight and footprint of the magnets. The study of a GaToroid system requires the integration of several aspects of physics and engineering. In this framework, the focus of this research is on the design of the superconducting coils integrated with beam optics and particle tracking analyses. The first part of the thesis illustrates the optimization of the toroidal magnet. Coupling two-dimensional particle tracking and magnetic field calculations, an algorithm was developed to identify optimal gantry configurations that maximize the energy acceptance of the system. Two solutions composed of 16 coils, differing in high and low values of engineering current density, were investigated. In line with current clinical requirements, the beams converged at the isocenter within 1 mm over the whole treatment energy spectrum for both configurations. The second part of the thesis describes the algorithm implemented for the two- and three-dimensional particle tracking. Building upon the results of the magnetic optimization, a linear beam optics formalism was developed to determine the focusing properties of GaToroid. The third part of the thesis focuses on the engineering design of the low current density solution. Using two thermo-electric models, lumped and one-dimensional, the Nb-Ti and ReBCO cable geometries were validated, together with the quench protection system. Furthermore, analytical and numerical studies on mechanics made it possible to estimate the overall footprint and weight of the system. Results show that, compared with the state-of-the-art gantries, the proposed GaToroid solution has the potential to be more compact and lighter by at least a factor two. Finally, the last part of the thesis describes the design of a scaled-down demonstrator wound with ReBCO tapes. Studies on quench protection, mechanics and experimental implementation aimed at testing the use of ReBCO technology for GaToroid coils are discussed. In conclusion, this work presents the first overall description of a GaToroid system, ranging from the analytical definition, magnetic optimization, particle tracking and magnet engineering. The investigation of this new toroidal paradigm for gantries represents a quantum step toward more compact and less expensive solutions for hadron therapy centres.

EPFL2021