Development of superconductive magnets

Survey of superconductive magnets considers - stabilization problems, advances in materials and their uses, and design evolution. Uses of superconducting magnets in particle accelerators and bubble chambers, as well as possible applications in magnetohydrodynamic and thermonuclear power generation and levitation are discussed

High-temperature superconducting ring magnet

Many electrical engineering applications such as motors and generators use permanent magnets which approximately account for 45% of their electricity consumption. The conventional magnets in use have a maximum field of around 1.5-2 T. High performance superconducting materials such as REBCO have facilitated the development of superconducting magnets. Superconducting bulk magnets and stacks of tapes have already demonstrated the extraordinary potential to trap magnetic fields of very high order with very compact sizes. This has significantly increased the efficiency of rotating machines and improved power/torque density, while having low synchronous reactance with large overloading capacity, high transient stability with low noise and harmonic content with the additional cost of cooling. This thesis focuses on a new type of superconducting magnet which uses superconducting tape as the field source. The most significant limiting factor for superconducting magnets is their size.;This new superconducting magnet has made possible the development of HTS magnets with flexible sizes by splitting the 2G HTS tapes to form the persistent current rings. By stacking HTS closed loop rings into a compact magnet, our HTS ring magnet has been proven to generate a trapped magnetic field higher than 5 T. The main advantage of the new magnet compared to existing trapped field HTS magnets is that the magnetic field lies parallel to the ab plane of the HTS, leading to higher critical currents in the same magnetic field. This thesis reports our key findings so far. Two different stacking configuration magnet samples were tested using the field cooling magnetization at 25 K and 4.2 K, with magnet diameter 90 mm and 150 mm, respectively. Over 4.6 T of the trapped field has been reported by using Super Power tapes with a field cooling process at 25 K, which is the highest field trapped in the ring magnets for first configuration. A new stacking design was proposed to improve magnetic field distribution within the magnet and has the potential to trap more magnetic field with the estimated trap field of 9.4 T at 4.2 K. A three dimensional model was developed to simulate the performance of the ring magnets, and good agreements between experiment and simulation have been achieved. The new HTS permanent magnet with improved field homogenisation and large diameter is promising for medical imaging applications, as well as propulsion applications.Many electrical engineering applications such as motors and generators use permanent magnets which approximately account for 45% of their electricity consumption. The conventional magnets in use have a maximum field of around 1.5-2 T. High performance superconducting materials such as REBCO have facilitated the development of superconducting magnets. Superconducting bulk magnets and stacks of tapes have already demonstrated the extraordinary potential to trap magnetic fields of very high order with very compact sizes. This has significantly increased the efficiency of rotating machines and improved power/torque density, while having low synchronous reactance with large overloading capacity, high transient stability with low noise and harmonic content with the additional cost of cooling. This thesis focuses on a new type of superconducting magnet which uses superconducting tape as the field source. The most significant limiting factor for superconducting magnets is their size.;This new superconducting magnet has made possible the development of HTS magnets with flexible sizes by splitting the 2G HTS tapes to form the persistent current rings. By stacking HTS closed loop rings into a compact magnet, our HTS ring magnet has been proven to generate a trapped magnetic field higher than 5 T. The main advantage of the new magnet compared to existing trapped field HTS magnets is that the magnetic field lies parallel to the ab plane of the HTS, leading to higher critical currents in the same magnetic field. This thesis reports our key findings so far. Two different stacking configuration magnet samples were tested using the field cooling magnetization at 25 K and 4.2 K, with magnet diameter 90 mm and 150 mm, respectively. Over 4.6 T of the trapped field has been reported by using Super Power tapes with a field cooling process at 25 K, which is the highest field trapped in the ring magnets for first configuration. A new stacking design was proposed to improve magnetic field distribution within the magnet and has the potential to trap more magnetic field with the estimated trap field of 9.4 T at 4.2 K. A three dimensional model was developed to simulate the performance of the ring magnets, and good agreements between experiment and simulation have been achieved. The new HTS permanent magnet with improved field homogenisation and large diameter is promising for medical imaging applications, as well as propulsion applications

Technologies for Delivery of Proton and Ion Beams for Radiotherapy

Recent developments for the delivery of proton and ion beam therapy have been significant, and a number of technological solutions now exist for the creation and utilisation of these particles for the treatment of cancer. In this paper we review the historical development of particle accelerators used for external beam radiotherapy and discuss the more recent progress towards more capable and cost-effective sources of particles.Comment: 53 pages, 13 figures. Submitted to International Journal of Modern Physics

Using LSTM recurrent neural networks for monitoring the LHC superconducting magnets

The superconducting LHC magnets are coupled with an electronic monitoring system which records and analyses voltage time series reflecting their performance. A currently used system is based on a range of preprogrammed triggers which launches protection procedures when a misbehavior of the magnets is detected. All the procedures used in the protection equipment were designed and implemented according to known working scenarios of the system and are updated and monitored by human operators. This paper proposes a novel approach to monitoring and fault protection of the Large Hadron Collider (LHC) superconducting magnets which employs state-of-the-art Deep Learning algorithms. Consequently, the authors of the paper decided to examine the performance of LSTM recurrent neural networks for modeling of voltage time series of the magnets. In order to address this challenging task different network architectures and hyper-parameters were used to achieve the best possible performance of the solution. The regression results were measured in terms of RMSE for different number of future steps and history length taken into account for the prediction. The best result of RMSE=0.00104 was obtained for a network of 128 LSTM cells within the internal layer and 16 steps history buffer

EUCARD magnet development

The FP7-EuCARD work package 7 (WP7), "HFM: Superconducting High Field Magnets for higher luminosities and energies" is a collaboration between 12 European institutes and firms with the objective of developing high field magnet technology. WP7 foresees to construct a 13 T dipole with a 100 mm aperture, a B = 6 T high temperature superconductor (HTS) dipole insert, a superconducting HTS link and a superconducting helical undulator.Comment: 5 pages, contribution to the EuCARD-AccNet-EuroLumi Workshop: The High-Energy Large Hadron Collider, Malta, 14 -- 16 Oct 2010; CERN Yellow Report CERN-2011-003, pp. 45-4

Coupling single molecule magnets to quantum circuits

In this work we study theoretically the coupling of single molecule magnets (SMMs) to a variety of quantum circuits, including microwave resonators with and without constrictions and flux qubits. The main results of this study is that it is possible to achieve strong and ultrastrong coupling regimes between SMM crystals and the superconducting circuit, with strong hints that such a coupling could also be reached for individual molecules close to constrictions. Building on the resulting coupling strengths and the typical coherence times of these molecules (of the order of microseconds), we conclude that SMMs can be used for coherent storage and manipulation of quantum information, either in the context of quantum computing or in quantum simulations. Throughout the work we also discuss in detail the family of molecules that are most suitable for such operations, based not only on the coupling strength, but also on the typical energy gaps and the simplicity with which they can be tuned and oriented. Finally, we also discuss practical advantages of SMMs, such as the possibility to fabricate the SMMs ensembles on the chip through the deposition of small droplets.Comment: 23 pages, 12 figure