Calibration of a polarization measurement station
A hyperpolarized, standard coil technology, applied in measurement devices, measurement of magnetic variables, magnetic resonance measurement, etc., can solve problems such as no way to check, inconvenient to carry strong magnetic field NMR magnets and spectrometers, etc.
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example 1
[0090] a bag 3 He, in the fairly uniform supporting magnetic field of the polarimetric stand, looks to the polarimetric circuit like a loosely coupled coil with a large but finite Q.
[0091] To demonstrate the proof-of-concept, a model circuit was built using the coaxial coil geometry. The components used for the transfer criteria were selected as shown in Table 1 in order to approximate, but not actually satisfy, the oscillation conditions. It should be noted that the R values in Table 1 are approximate, using the tuning box and coil as the LRC tank, so the R values listed below represent the coil resistance plus the additional resistance in the tuning box. A 350-turn NMR surface coil and 22nF capacitor is used to divert the standard LC tank and is vertically displaced 1 above the pickup coil 3 / 4 inch. Within the resolution range of the normal display, the Q and resonant frequency of the polarization measurement circuit were not changed by the addition of the trans...
example 2
[0096] refer to Figure 11 , using 8 inch diameter, 1 / 2 inch thick PVC pipe as the coil structure 102, was constructed as a concentric coplanar transfer standard 110. 100 turns of wire 104 were wound in the channel 106 machined on the coil structure 104. The coil is tuned to approximately match the polarization measurement circuit, and the effect of the transfer standard on the polarization measurement circuit parameters is determined (by looking for changes in the "coil test" response). Repeat this process, removing a few turns at a time, until there is no visible change in response. It was determined that only 5 turns are required for the transfer standard.
[0097] Then build a Venturi oscillator circuit around this 5-turn coil and measure the apparent polarization. It was decided to reduce the apparent polarization by a factor of approximately 15 by adding an additional 220 μH inductance (Coilcraft #90-41) in series with the transfer standard coil as above (it should be ...
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