Field-cycling NMR Relaxometry: Instrumentation, Model Theories and Applications
Chapter 5: Specific Aspects of the Design of Field-cycling Devices
Published:11 Oct 2018
Special Collection: 2018 ebook collectionSeries: New Developments in NMR
D. M. Sousa, in Field-cycling NMR Relaxometry: Instrumentation, Model Theories and Applications, ed. R. Kimmich, The Royal Society of Chemistry, 2018, ch. 5, pp. 118-137.
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The advent of power semiconductors constituted a turning point in the development, performance and features of fast field-cycling NMR devices. During the last decades of the twentieth century, fast field-cycling (FFC) relaxometers were developed, taking advantage of different types of semiconductors together with the development of computational tools to optimise the design and running of such equipment. Among other approaches, since the 1990s, solutions based on insulated-gate bipolar transistors (IGBTs) were developed, which can be seen has a breaking point compared with the standard approaches up to that time. In this work, the design aspects of FFC relaxometers based on IGBTs are described. Starting from the general conception of FFC devices, aspects of the design of the power systems, the magnets and the control chains of three generations of FFC relaxometers are presented.