Varian, Inc.

James Finnigan

Weston A Anderson

Wai Ha Wong

Joseph Murphy

Thomas De Swiet

Sean T Burns

Marco A Romo

NMR (Nuclear Magnetic Resonance) capacitor switches allow for adjusting the resonant frequency ranges of NMR measurement circuits by inserting or removing capacitors having different values into the circuits. A change of position of a single switching member is used to change the contact state of at least two capacitors. In some embodiments, at least two pairs of external contacts are disposed at distinct longitudinal levels along a channel, and a slider including multiple longitudinally-spaced capacitors is moved longitudinally within the channel to establish electrical contact between the external contact pairs and different capacitors along the slider. In other embodiments, two capacitor columns are disposed along the channel, and a movable longitudinal member establishes electrical contact between the two columns at different longitudinal levels along the columns. In some embodiments, capacitor covers or intracapacitor blocks are provided to protect the capacitors. An auxiliary inductor may also be inserted into the circuits.

Capacitor switches for NMR

A single RF port, multiply-resonant circuit comprises coupled resonant sub-circuits coupled through an adjustable reactive element exhibiting a dynamic range that includes a value of the reactive component of sufficient magnitude to produce an impedance producing substantial mutual isolation of the sub-circuits.

Multi-functional NMR probe

According to some embodiments, NMR (nuclear magnetic resonance) circuits include one or more variable capacitors each having two concentric cylindrical conductors. The inner conductor is connected to an upper external contact disposed closer to the NMR sample coil than the outer conductor. The inner conductor and upper contact are generally exposed to higher voltages than the outer conductor, and the upper contact is shorter than the outer conductor. Capacitance adjustment is performed by moving the inner conductor longitudinally within the outer conductor. Using a relatively short contact for the higher-voltage capacitor node allows reducing the surface area most conducive to arcing, and allows reducing lead lengths and stray capacitances. Shorting the capacitor may be performed by moving the inner conductor to contact a capacitor base situated opposite the upper external contact.

NMR systems employing inverted variable capacitors

A high resolution NMR probe having two or more resonators, an inner resonator which is closely coupled to a sample and is used to stimulate and receive a response from one nuclear species, and an outer resonator to induce transitions in another nuclear species, wherein the resonators may be provided with cooling capability and may be made of superconducting material, and wherein the inner resonator may be a saddle coil or a birdcage coil with capability of being tuned, and wherein the outer resonator may be one or more spiral wound saddle coil.

NMR probe having an inner quadrature detection coil combined with a spiral wound outer coil for irradiation

An insertable wand is used in a multi-nuclear NMR probe enabling the probe to detect and obtain data from various combinations of nuclei. The particular combination of frequencies is determined by various electrical components, and parts within the wand that are designed to cooperate with a tube, to form an adjustable &frac14; wave assembly. The adjustable &frac14; wave assembly component in the wand comprises a metal rod with an adjustable conductive collar and spring contacts such that when inserted into the tube, the rod and the tube to form an adjustable &frac14; wave circuit or a &frac14; wave shorted stub. The tube may form part of the wand or the probe. When the wand is plugged into the probe, the combination of the NMR coil within the probe and the adjustable &frac14; wave shorted stub provides means for the NMR circuit to resonate at two separate frequencies.

Multinuclear wands

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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Saratoga, CA, United States of America

James Finnigan