Design and Construction of a 2.4 T Air-Cored Copper Magnet for Fast Field-Cycling NMR

Abstract

The theoretical magnet-coil optimization formalism described previously ¹⁾ has been extended to calculate a still stronger and more homogeneous (10⁵) low-inductance (6 mH) copper magnet with a maximum magnetic flux density of 2.4 T for fast field cycling NMR, where field switches of the order of milliseconds are necessary. These calculations were combined with a novel, computer controlled coil cutting technique from copper and aluminium tubes, which allows us to produce much narrower gaps between the conductor windings (0.1 mm) and a more precise sawing path (0.01 mm) of the sophisticated coil geometry than in our original construction. The cutting procedure was successfully tested on a smaller 1.4 T system, and the final magnet is under construction. It will considerably improve both the signal sensitivity and the spectral resolution of selective frequency dependent relaxation measurements of deuterons in difficult systems, like liquid crystals ²⁾.