Current source of a FFC NMR relaxometer linearly controlled

A Fast Field Cycling (FFC) Nuclear Magnetic Resonance (NMR) relaxometer combines optimized magnets (low volume and power losses) and power apparatus that integrate power supplies and control methods. The magnet of a FFC NMR relaxometer determines the requirements of the main power supply. As main requirement, the magnet current should be controlled linearly in order to control the magnet flux density. In addition, the current control should be accurate and having an adequate thermal stability. In this paper, framed by the main blocks that integrate a FFC NMR relaxometer, the topology of the magnet current source is presented. The operating modes and the control methodology are also described. Experimental results are presented validating the proposed solution according to the application requirements. A power losses analysis supported by experimental results is performed for the generalized operating modes.