Hoffmann C.,Industrial Research Ltd. |
Walsh R.,Industrial Research Ltd. |
Karrer-Mueller E.,Industrial Research Ltd. |
Pooke D.,HTS 110 Ltd
Flux pumps are devices to energize superconducting magnets and are embedded in the cryo-system. Therefore heat loss through current leads is eliminated allowing for more efficient cooling design. This is particularly advantageous for HTS based magnet systems which cannot be operated in a persistent mode because of the inability to form superconducting joints. We recently developed a flux pump based on YBCO thin films capable of generating currents over 200A. In this paper we investigate variations of the design by comparing a flux pump employing an YBCO coated disc with a 2G wire based system. Results are discussed with regard to voltage generation and current capacity and were used to design a prototype 1T magnet system made of 2G HTS wire. © 2011 Published by Elsevier B.V. Selection and/or peer-review under responsibility of the Guest Editors. Source
HTS 110 Ltd | Date: 2015-05-07
A passive magnetic field shim arrangement including a plurality of shim pairs. For shimming a number of magnetic field harmonics, each shim pair may include a first shim and a second opposite and substantially equal shim, each shim pair being configured for shimming one of the magnetic field harmonics. Each shim pair may include a first shim of order N and a second opposite and substantially equal shim of order N, the first and second shims together defining a magnetic field shim correction of order N1. Each shim may include one or more shim elements arranged on a non-magnetic tubular support, the tubular supports being dimensioned such that the tubular supports may be arranged concentrically in relation to each other. A magnetic field may be shimmed by providing a shim pair configured for shimming a magnetic field harmonic, the shim pair including a first shim and a second opposite and substantially equal shim and symmetrically adjusting an axial position of the first shim and an axial position of the second shim to provide a desired shimming magnitude in order to shim the magnetic field harmonic.
HTS 110 Ltd | Date: 2013-08-07
An assembly for generating a superconducting magnetic field with high stability comprises a main power supply unit arranged to provide a main current to generate a superconducting magnetic field, a magnetic field measurement device for measuring the generated magnetic field, and an auxiliary power supply unit arranged to output an auxiliary current based on the measured magnetic field.
Huang T.,HTS 110 Ltd |
Caughley A.,Industry Research Ltd.
AIP Conference Proceedings
Industrial Research Ltd has developed a diaphragm based low-cost pressure wave generator technology for Stirling and pulse tube cryogenic refrigerators. To quickly design and optimize a refrigerator based on a diaphragm pressure wave generator, one-dimensional analysis plays a very important role. However, due to the large cross-section change between the pressure wave generator and the heat exchanger, one-dimensional design code can't give accurate results without adjusting empirical heat transfer and friction coefficients. Therefore, multi-dimensional analysis is needed to verify one-dimensional results and determine empirical coefficients. In our previous work, a two-dimensional axisymmetric Computational Fluid Dynamics (CFD) model was developed to simulate oscillating fluid flow and heat transfer in a diaphragm pressure wave generator and validated by a series of validation experiments. In this study, the validation experiments were modeled using Sage commercial code. Results obtained from the Sage model were compared with those from CFD simulations and validation experiments. We present the results to assist to determine the empirical heat transfer coefficients in Sage for the cases with great cross-section change between a pressure wave generator and a heat exchanger. © 2012 American Institute of Physics. Source
Hoffmann C.,Industrial Research Ltd. |
Pooke D.,HTS 110 Ltd |
Caplin A.D.,Imperial College London
IEEE Transactions on Applied Superconductivity
Magnets fabricated with HTS wire can not be operated in a true persistent mode as superconducting joints of sufficient technological quality have not been achieved to date. In order to maintain a constant magnetic field in a HTS magnet a power supply has to be permanently employed, which then leads to heat losses in the cryo-system through the employment of current leads. By using a flux pump these losses can be minimized. We present a new flux pump based on 2G HTS wire. This device energized at 77 K a 2.7 mH 2G HTS double-pancake coil to its critical current of 49 A within 112 seconds. The operating principle will be described and data of the current ramping is shown. Considering the simplicity of the device and the potential to increase the generated current to 200 A and more, this new flux pump is very promising for many superconducting devices including HTS and LTS magnets and rotating machines. © 2010 IEEE. Source