Coil design for large-volume high-B-1 homogeneity for solid-state NMR applications

The design of a solenoidal NMR coil with high-B-1 homogeneity for high-frequency solid-state NMR is described. The coil is made of thin ribbon of continuously variable width. The width is varied to minimize inhomogeneity in the axial direction. The field distribution throughout the entire volume of the sample was taken into account. The gap between turns is constant and kept small to minimize field inhomogeneity in the radial direction. For large samples in particular, coils of this design tested at 300 MHz show significantly better homogeneity than helical coils with constant pitch or coils with variable pitch but fixed ribbon width. (C) 1996 Academic Press, Inc.