Adjusting homogeneity of magnetic field gradient in NMR system - regulating current through correction winding, or varying number of elements or positioning of ferromagnetic piece, while observing NMR frequency spectrum from specimen until total compensation of gradient is achieved

摘要

Analysis specimens are selectively arranged or selected from samples already installed at places where a correction winding or ferromagnet acts, for a given gradient predominant, on the one hand, and symmetric and/ or opposed on the other hand. The correction winding to be adjusted is supplied, and the NMR signal is sampled and displayed after conversion into the frequency domain. The supply current in the correction winding is adjusted whilst the spectral evolution of the NMR signal from the analysed samples is observed in real time, to obtain a configuration of the spectrum corresponding to a total compensation of the influenced gradient. These operations are effected for the assembly of correction windings or ferromagnetic pieces according to a predetermined order, a function of the configuration of the magnetically-homogeneous analysis volume.. ADVANTAGE - Permits rapid adjustment of gradient assemblies in simple and methodical manner.