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Design of current power sources for a FFC NMR apparatus: a comparison

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Resumo:The power supply of a Fast Field Cycling Nuclear Magnetic Resonance apparatus is typically a current power source, with characteristics that are not fulfilled by most of the commercially available power supplies. This current source is used to supply a specially designed magnet, and should be able to drive a cycling current with a slew rate lower than 3 A/ms. In this paper, two solutions for this current source are designed and discussed. The first uses two power supplies: the main voltage source and an auxiliary power supply to guarantee the current transitons from the low level to the high level. In the second solution the auxiliary power supply is replaced by a capacitor. To guarantee the required current slews rates, the possibility of using resistors to dissipate the energy store in the magnet is also discussed.
Autores principais:Roque, António
Outros Autores:Pinto, Sónia F.; Santana, João; Sousa, Duarte; Margato, Elmano; Maia, José
Assunto:Current power source Fast field cycling nuclear magnetic resonance Fast transients
Ano:2012
País:Portugal
Tipo de documento:documento de conferência
Tipo de acesso:acesso restrito
Instituição associada:Instituto Politécnico de Lisboa
Idioma:inglês
Origem:Repositório Científico do Instituto Politécnico de Lisboa
Descrição
Resumo:The power supply of a Fast Field Cycling Nuclear Magnetic Resonance apparatus is typically a current power source, with characteristics that are not fulfilled by most of the commercially available power supplies. This current source is used to supply a specially designed magnet, and should be able to drive a cycling current with a slew rate lower than 3 A/ms. In this paper, two solutions for this current source are designed and discussed. The first uses two power supplies: the main voltage source and an auxiliary power supply to guarantee the current transitons from the low level to the high level. In the second solution the auxiliary power supply is replaced by a capacitor. To guarantee the required current slews rates, the possibility of using resistors to dissipate the energy store in the magnet is also discussed.