||An X(0) shim coil for precise magic-angle adjustment.
Matsunaga, Tatsuya ,
Mizuno, TakashiTakegoshi, K
Journal of magnetic resonance
8 , 2015-07 , Elsevier Inc.
A new method for precise setting of the spinning angle to the magic angle by using a saddle coil is described. The coil, which is referred to as an X(0) shim coil, is wound to produce a uniform static magnetic field B(x) perpendicular to the main magnetic field B(0). The magnetic field felt by a sample is a vector sum of the main field B(0) and the transverse field B(x) produced by the X(0) shim coil. Hence the angle between the spinner axis and the effective magnetic field can be controlled by current I supplied to the X(0) shim coil, leading to precise angle adjustment without backlash accompanied with a mechanical system conventionally used. It is shown that the angle range achieved is ±0.05° for I=±5A at B(0)=7T.