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The Earth's Field NMR (EFNMR) Instrument
The instrument contains three coaxial tubes
wrapped with wire, the coils. The three coaxial
tubes are pictured at right.3 The large outer coil is
the "polarizing coil," used to align sample spins.
The innermost coil, the B1 coil, measures and
excites precessing net magnetization. The middle
tube contains four coils: gradient coils to adjust
("shim") the magnetic field in the x, y and z
directions, and a second x coil that is used for
pulsed-gradient NMR. The electronics box, the
"spectrometer," communicates with the Prospa
software that is on a computer, sends power to the
coils as needed, and collects response from the B1
coil.
Figure 6. Magritek EFNMR coils (ref. 3)
As shown in Figure 7, at left, the x axis lies along the axes of
the tubes. The y and z axes are perpendicular to the probe's
axis, with z being along the Earth's magnetic field, BE.
Figure 7. EFNMR probe and axis
conventions. (ref. 3)
EFNMR.odt
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