title: Air core notch-coil magnet with variable geometry for fast-field-cycling NMR.
abstract: In this manuscript we present details on the optimization, construction and performance of a wide-bore (71 mm) α-helical-cut notch-coil magnet with variable geometry for fast-field-cycling NMR. In addition to the usual requirements for this kind of magnets (high field-to-power ratio, good magnetic field homogeneity, low inductance and resistance values) a tunable homogeneity and a more uniform heat dissipation along the magnet body are considered. The presented magnet consists of only one machined metallic cylinder combined with two external movable pieces. The optimal configuration is calculated through an evaluation of the magnetic flux density within the entire volume of interest. The magnet has a field-to-current constant of 0.728 mT/A, allowing to switch from zero to 0.125 T in less than 3 ms without energy storage assistance. For a cylindrical sample volume of 35 cm(3) the effective magnet homogeneity is lower than 130 ppm.
authors.affiliation: Laboratorio de Relaxometría y Técnicas Especiales, Grupo de Resonancia Magnética Nuclear, Facultad de Matemática, Astronomía y Física, Universidad Nacional de Córdoba and IFEG - CONICET, Córdoba, Argentina.
authors.forename: S
authors.initials: S
authors.lastname: Kruber
authors.affiliation: Laboratorio de Relaxometría y Técnicas Especiales, Grupo de Resonancia Magnética Nuclear, Facultad de Matemática, Astronomía y Física, Universidad Nacional de Córdoba and IFEG - CONICET, Córdoba, Argentina.
authors.forename: G D
authors.initials: GD
authors.lastname: Farrher
authors.affiliation: Laboratorio de Relaxometría y Técnicas Especiales, Grupo de Resonancia Magnética Nuclear, Facultad de Matemática, Astronomía y Física, Universidad Nacional de Córdoba and IFEG - CONICET, Córdoba, Argentina. Electronic address: anoardo@famaf.unc.edu.ar.
authors.forename: E
authors.initials: E
authors.lastname: Anoardo
mesh_terms: D000465:Algorithms; D004574:Electromagnetic Fields; D004867:Equipment Design; D006358:Hot Temperature; D009682:Magnetic Resonance Spectroscopy / Q000295:instrumentation*; D059346:Magnets; D013696:Temperature
keywords: Fast-field-cycling; Magnet system; Notch-coil; Optimization