Magnet design with high B(0) homogeneity for fast-field-cycling NMR applications

The design, construction, and performance of a low-inductance solenoidal coil with high B(0) homogeneity for fast-field-cycling NMR is presented. It consists of six concentric layers. The conductor width is varied to minimize the B(0) inhomogeneity in the volume of the sample. This is done using an algorithm which takes the real shape of the conductor directly into account. The calculated coil geometry can be manufactured easily using standard computerized numeric control equipment, which keeps the costs low. The coil is liquid cooled and produces a B(0) field of 0.95 T at 800 A. The field inhomogeneity in a cylindrical volume (diameter 5 mm, length 10 mm) is about 10 ppm, and the inductance is 190 microH. Switching times below 200 micros can be achieved. During 6 months of operation the coil has shown good stability and reliability.