AN NMR MULTIFID METHOD FOR MEASUREMENT OF MAGNETIC-FIELD GRADIENT

The described MULTIFID method, that allows measurement of the time characteristic of the magnetic field gradient G(z)(t), is based on the measurement of the instantaneous frequency Of FID signals periodically recorded immediately after switching off the gradient pulse. The method was used for a fast and sufficiently accurate determination of the pre-emphasis time and amplitude constants. The pre-emphasis filter used allowed us to shorten the decay time of the gradient magnetic field G(z) from 200 ms to 100 mus and, thereby, to carry out a good compensation for the influence of eddy currents for the purposes Of NMR spectroscopy and