Varian, Inc.

Thomas M Barbara

Thomas De Swiet

Alexander M J Hudson

Knut G Mehr

Matthew H Commens

Atholl A V Gibson

The NMR device with a magnet utilizes a composition exhibiting a desired value of magnetic susceptibility, wherein the composition comprises a metal ion selected from the group consisting of Gd, Feand Mnand an amorphous material using a ligand or chelating agent to solubilize the metal ion throughout the amorphous material, wherein the magnetic susceptibility of the composition exhibits a desired value at cryogenic temperatures such as nearly zero susceptibility at temperatures at or below 77 K.

Low temperature susceptibility compensation

An composition exhibiting a desired value of magnetic susceptibility, which can be used to fabricate components in an NMR device, and method thereof, wherein the composition comprises a metal ion selected from the group consisting of Gd, Feand Mnand an amorphous material using a ligand or chelating agent to solubilize the metal ion throughout the marphous material, wherein the magnetic susceptibility of the composition exhibits a desired value at cryogenic temperatures such as nearly zero susceptibility at temperatures at or below 77&#xb0; K.

The vacuum properties of a cryogenic NMR probe maintained at a desired operating temperature by a cold head heat exchanger are improved by a separate heat exchanger operating below the temperature of the cold head heat exchanger for maintaining cryo-pumping surfaces at a temperature below said selected operating temperature.

Efficiently cryo-pumped NMR cryogenic probe

The thermal performance and vacuum properties of a cryogenic NMR probe are improved when thermal control is implemented by conductive heat transfer to a cold head cooled by a heat exchanger to below the selected operating temperature. The heat load is manipulated by locating a heater to produce a more nearly constant heat load in conjunction with pulsed RF power and in one embodiment transferring such heater power through a common thermal path. In another embodiment, the heater power is conductively transferred directly to the heat exchanger.

Cryogenic NMR probe

An extended Maxwell pair has a pair of cylindrical gradient coils disposed coaxially, carrying equal currents in mutually opposite directions. Each of these gradient coils may be surrounded by a coaxially disposed cylindrically extended shield coil so as to cancel the magnetic field outside. For given values of radii of the gradient and shield coils, the length and the center-to-center separation of the pair of gradient coils are determined by numerically solving an equation which is derived from the condition that the currents through the gradient and shield coils should together generate a magnetic field inside with a linear gradient. The equation to be solved is derived by calculating the magnetic field by a Fourier-Bessel expansion method incorporating the condition that the shield coils do shield the magnetic field inside and cancel the field outside the system.

Extended maxwell pair gradient coils

A magnetic field generated by windings supported by a cylindrical former having axis Z is established in a desired direction forming an angle &PHgr; with respect to Z. Over an interval on Z, substantially constant value for the desired field and substantially vanishing orthogonal components are achieved by specifying the current distribution on the cylinder as a solution to field equations and then approximating said current distribution in a discrete conductor forming a plurality of anharmonic loops, nonlinearly spaced in accord with said solution.

RF coils for magic angle spinning probes

A coil set and its design is described for obtaining a magnetic field gradient oriented at a desired angle to a uniform magnetic field wherein the coils set is disposed on a cylinder with axis along the desired gradient direction.

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Mountain View, CA, United States of America

Thomas M Barbara