Varian, Inc.

Sean T Burns

Wai Ha Wong

Knut G Mehr

Thomas De Swiet

James Finnigan

Alexander M J Hudson

Marco A Romo

In some embodiments, a NMR spectrometer includes a NMR probe circuit component (e.g. RF coil insert, capacitor, inductor) in thermal and electrical contact with a cryogenically-cooled NMR probe support through a collet assembly. The collet assembly includes a collet assembly body connected to the probe support, a collet inserted into the collet assembly body, a pin connected to the probe circuit component, and a nut threaded over a back of the collet to secure the pin to the collet. The collet assembly body is connected to the probe circuit component and the pin is connected to the probe support. A heat exchanger may be in thermal contact with the probe support. The collet assembly provides a demountable, compact, reliable, low-resistance, and strong thermal and electrical connection particularly suited for use in NMR probes, which are commonly subject to stringent spatial and other NMR-compatibility design constraints.

Demountable cryogenic NMR connection assembly systems and methods

According to one aspect, a nuclear magnetic resonance (NMR) radio-frequency (RF) coil of an NMR spectrometer includes oppositely-facing arches at opposite longitudinal ends of the coil window, along shielded regions of the coil. The arched coil shapes allow situating the transverse parts of the coil away from the interfaces between the sample measurement volume and coil shields while minimizing the additional coil length and thus coil inductance and capacitance needed to move the transverse conductors away from interfaces. Moving the transverse parts of the coil away from the measurement volume facilitates shimming. The coil may be lifted on a plurality of longitudinal support rods spaced around a circumference of the coil, in order to reduce the capacitance between the coil and associated shields.

Arched saddle-shaped NMR RF coils

According to some embodiments, low-temperature (cryogenic) nuclear magnetic resonance (NMR) probe fixed capacitors include thermally-conductive dielectric layers serving to thermally connect the capacitors to a cryogenic heat sink. For example, a sapphire layer may be metalized on opposite sides to form copper capacitor plates, and along an edge to form a copper heat sink contact. Heat generated by RF currents during an operation of an NMR circuit including such a capacitor is discharged through the thermally-conductive dielectric to the heat sink. Cooling cold-probe circuit components such as capacitors through thermally-conductive capacitor dielectrics allows reducing perturbations introduced into the circuit by components such as heat sinks.

Cryogenic NMR probe capacitors with dielectric heat sinks

A birdcage resonator has a pair of conductor rings separated from each other along a central axis and a plural number of axially disposed conductor rungs, which extend between the rings and are evenly spaced around the central axis. Each of the rungs has a sectional shape with thickness or a radial extension comparable to or greater than its width or its azimuthal extension. Measures of the width and thickness of the rungs may be determined by using them as parameters to calculate the values of Q factor from an analytical procedure to locate parameter value ranges corresponding to maximal Q. Geometric calculations for filling factor yield ranges of parameters providing for compromise parameter values. Saddle coils have been found to exhibit similar enhancement of Q with radially oriented conductor cross section.

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East Palo Alto, CA, United States of America

Sean T Burns