NMR measurement method
There is disclosed an NMR measurement method and NMR apparatus in which the temperature of the NMR detection coil or the RF irradiation coil hardly varies if pulsed RF power is applied to the coil during NMR measurements. The apparatus includes the detection coil or the RF irradiation coil, a first RF power application means for applying RF power of a frequency necessary for measurement of NMR signals, a second RF power application means for applying RF power of a frequency not affecting the measurement of NMR signals, and a control means for controlling the two power application means such that the sum of the RF power applied to the coil from the first application means and the RF power applied to the coil from the second application means is kept almost constant.
1. An NMR measurement method comprising the steps of:
placing an RF power meter on the cable connected between an RF power source and an NMR detection coil or an RF irradiation coil;
applying RF power of a frequency not affecting measurement of an NMR signal from an NMR specimen to either a detection coil or the RF irradiation coil such that reflected RF power is produced and measured by the RF power meter; and
detecting an increase in the temperature of the detection coil or the RF irradiation coil from the strength of the measured reflected RF power.
2. The NMR measurement method set forth in claim 1 , wherein said detection coil or the RF irradiation coil has a resonance mode which is different from a resonance mode at a measurement frequency for the NMR signal and which does not affect the measurement of the NMR signal.
3. The NMR measurement method set forth in claim 1 , wherein said frequency not affecting the measurement of the NMR signal is shifted from a measurement frequency for the NMR signal by a given frequency and can resonate in the same resonance mode as the measurement frequency for the NMR signal.
4. The NMR measurement method of claim 1 , wherein the RF power of the frequency not affecting the measurement of the NMR signal can be so adjusted that the ratio of the RF power reflected from the detection coil or the RF irradiation coil to the RF power applied to the detection coil or the RF irradiation coil is minimized.