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- Title
Determination of the limits of applicability of the giulotto method when measuring longitudinal relaxation time in nuclear magnetic flowmeters-relaxometers.
- Authors
Davydov, Vadim V.; Goldberg, A. A.; Dudkin, V. I.; Davydov, R. V.
- Abstract
The method of nuclear magnetic resonance, which is currently the most common in research and control of parameters of condensed matter, and the nuclear magnetic flowmeters and relaxometers that implement this method are described. The features of determining the times of longitudinal and transverse relaxation in nuclear magnetic flowmeters-relaxometers in various modes of medium flow while monitoring its parameters have been established. The advantages of the modulation technique for signal recording in nuclear magnetic flowmeters-relaxometers compared to other recording methods are noted. Using various approximations by the Giulotto method from the Bloch equations, a relation was obtained to determine the longitudinal relaxation time based on the results of measurements of two values of nuclear magnetic resonance signal amplitudes or resonance frequencies at different modulation frequencies. It has been experimentally proven that this relationship has a number of limitations when applied to a flowing liquid. These limitations are associated with the method of recording nuclear magnetic resonance signals and the possibility of their formation at different modulation frequencies of a constant magnetic field, and the amplitudes of the signals differ from each other beyond the measurement error. The reasons that led to such a discrepancy in the ratio of determining the time of longitudinal relaxation have been established. The limits of applicability of the obtained relation are found and it is experimentally proven that within these limits it can be used for reliable measurements of relaxation constants. Based on experimental data, the relationship for determining the longitudinal relaxation time was studied. It has been proven that in a number of cases it is impossible to determine the required time using the specified relationship, although nuclear magnetic resonance signals of the flowing liquid are recorded and it has relaxation times. The results obtained make it possible to eliminate errors when using the nuclear magnetic resonance method to study flowing liquids and solve a number of complex problems in the energy, oil, chemical and pharmaceutical industries.
- Subjects
NUCLEAR magnetic resonance; BLOCH equations; CONDENSED matter; MEASUREMENT errors; MAGNETIC fields; NUCLEAR magnetic resonance spectroscopy
- Publication
Measurement Techniques, 2024, Vol 66, Issue 12, p958
- ISSN
0543-1972
- Publication type
Article
- DOI
10.1007/s11018-024-02312-2