NMR polarization monitoring coils, hyperpolarizers with same, and methods for determining the polarization level of accumulated hyperpolarized noble gases during production
First Claim
1. A hyperpolarizer for producing polarized noble gases, comprising:
- an optical pumping cell having a non-polarized gas inlet port and a polarized gas outlet port;
a magnetic field source operably associated with said optical pumping cell, said magnetic field source configured to provide a region of homogeneity;
a NMR coil having first and second opposing ends, said first end positioned adjacent said optical pumping cell within said region of homogeneity;
a cryogenic accumulator in fluid communication with said optical pumping cell outlet port;
a polarized gas dispensing outlet in fluid communication with said cryogenic accumulator;
a polarized gas exit flow line extending between said cryogenic accumulator and said polarized gas dispensing outlet; and
a secondary reservoir positioned adjacent said NMR coil second end in fluid communication with said polarized gas exit flow path, wherein said NMR coil is configured such that during operation of said hyperpolarizer, said NMR coil excites a quantity of polarized gas positioned in one of said optical cell and said secondary reservoir.
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Abstract
Hyperpolarizers which produce hyperpolarized noble gases include one or more on-board NMR monitoring coils configured to monitor the polarization level of the hyperpolarized gas at various production points in the polarized gas production cycle. A dual symmetry NMR coil is positioned adjacent the optical pumping cell and is in fluid communication with a secondary reservoir in fluid communication with the polarized gas dispensing or exit flow path. This can measure the post-thaw polarization of the gas “on-board” the polarizer. Alternately or additionally, a NMR monitoring coil is assembled to the exit port portion of tie optical pumping cell to give a more reliable indication of the polarization level of the gas as it flows out of the gas optical pumping cell. Another NMR monitoring coil can be positioned in a cryogenic bath adjacent a quantity of frozen polarized 129Xe to determine the polarization level of the frozen gas.
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Citations
40 Claims
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1. A hyperpolarizer for producing polarized noble gases, comprising:
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an optical pumping cell having a non-polarized gas inlet port and a polarized gas outlet port;
a magnetic field source operably associated with said optical pumping cell, said magnetic field source configured to provide a region of homogeneity;
a NMR coil having first and second opposing ends, said first end positioned adjacent said optical pumping cell within said region of homogeneity;
a cryogenic accumulator in fluid communication with said optical pumping cell outlet port;
a polarized gas dispensing outlet in fluid communication with said cryogenic accumulator;
a polarized gas exit flow line extending between said cryogenic accumulator and said polarized gas dispensing outlet; and
a secondary reservoir positioned adjacent said NMR coil second end in fluid communication with said polarized gas exit flow path, wherein said NMR coil is configured such that during operation of said hyperpolarizer, said NMR coil excites a quantity of polarized gas positioned in one of said optical cell and said secondary reservoir. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8)
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9. A secondary reservoir for a hyperpolarizer unit configured to hold a quantity of hyperpolarized noble gas therein, comprising:
a body with opposing first and second end portions defining a gas flow path therebetween, said first end portion configured to capture a quantity of hyperpolarized gas therein, said second end portion having an opening formed therein, said second end configured to engage with a hyperpolarizer during operation thereof thereby allowing hyperpolarized gas to flow therein when engaged with a portion of a gas flow line in the hyperpolarizer. - View Dependent Claims (10, 11, 14, 15, 16, 17, 18, 19)
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12. A dual symmetry NMR coil for monitoring the level of polarization associated with polarized gas in two different regions, comprising:
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a coil body having first and second opposing flanges and an intermediate coil receiving section positioned therebetween;
a wire coil configured with a plurality of turns positioned about said intermediate coil receiving section, wherein said first flange has a first thickness and said second flange has a second thickness, and said first and second thicknesses are substantially the same, and wherein said NMR coil is configured to monitor the level of polarization associated with a quantity of hyperpolarized noble gas.
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13. A hyperpolarizer for producing polarized noble gases, comprising:
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an optical pumping cell having a primary body and a longitudinally extending polarized gas outlet port with an outer surface; and
a first NMR coil having first and second opposing ends and defining a center aperture therethrough, said first NMR coil positioned on said outlet port such that a portion of said outlet port longitudinally extending port extends through said first NMR coil aperture, said NMR coil first end being positioned adjacent said primary body of said optical pumping cell, wherein said first NMR coil is configured such that during operation of said hyperpolarizer said first NMR coil excites a quantity of polarized gas positioned proximate to said optical cell outlet port.
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20. A hyperpolarizer for producing optically pumped polarized noble gases, comprising:
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an optical pumping cell having an unpolarized gas inlet port and a polarized gas outlet port and a primary body;
a cryogenic accumulator in fluid communication with said optical pumping cell outlet port, comprising;
an elongated closed end tube defining a polarized gas collection chamber for holding a quantity of collected polarized gas therein, said gas collection chamber being operably associated with first and second sealable valves;
a cryogenic bath, wherein said collection chamber is immersed into said cryogenic bath;
a magnetic field source arranged to provide a magnetic field with a region of homogeneity adjacent said collection chamber in said cryogenic bath;
a first NMR coil positioned in said cryogenic bath adjacent said closed end of said tube in said magnetic field region of homogeneity;
a polarized gas-dispensing outlet in fluid communication with said cryogenic accumulator; and
a polarized gas exit flow path extending from said cryogenic accumulator to a polarized gas dispensing outlet, wherein said first NMR coil is configured such that during operation of said hyperpolarizer, said first NMR coil monitors the level of polarization associated with the collected polarized gas held proximate to the closed end of said collection tube. - View Dependent Claims (21, 22, 23, 24, 25, 27, 28, 29, 30, 31, 32)
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26. A method of monitoring the polarization level of hyperpolarized noble gas during production thereof, comprising the steps of:
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polarizing a quantity of noble gas in an optical pumping chamber;
directing the polarized noble gas in the optical pumping chamber to a gas collection path;
providing a magnetic field having a region of homogeneity, the region of homogeneity including at least a volume of space associated with a portion of the optical pumping chamber and the gas collection path proximate to the optical pumping chamber;
positioning a first NMR coil adjacent the gas flow path in the magnetic field region of homogeneity;
exciting the polarized gas by transmitting an excitation signal to the first NMR coil; and
measuring the level of polarization associated with the hyperpolarized gas adjacent the NMR coil to thereby monitor the level of polarization associated with the polarized gas in a region of the polarizer adjacent the polarized gas flow path.
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33. A hyperpolarized gas optical pumping cell having an integrated NMR coil, comprising:
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an optical pumping cell having a primary body and at least one longitudinally extending leg portion; and
a NMR coil having opposing first and second ends and an aperture formed through the center thereof, said aperture being sized and configured to receive a portion of said longitudinally extending leg therethrough. - View Dependent Claims (34, 35, 36, 38, 39, 40)
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37. A method for releasing the post-thaw cryogenically accumulated hyperpolarized gas from a cold finger collection container operably associated with exit flow path plumbing, comprising the steps of:
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cryogenically accumulating a quantity of hyperpolarized gas as a frozen sample in a cold finger;
monitoring a pressure associated with the cryogenically collected hyperpolarized gas sample held in the cold finger;
thawing at least a portion of the quantity of frozen hyperpolarized gas sample in the cold finger;
increasing the pressure in the cold finger facilitating the phase transition of the hyperpolarized gas from a substantially frozen sample into a thawed fluid sample; and
releasing the thawed fluid hyperpolarized sample as a gas from the cold finger responsive to a predetermined pressure associated with the cold finger during said monitoring step.
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Specification