Stacked multistage Joule-Thomson cryostat
First Claim
1. A stacked multistage Joule-Thomson cryostat, comprising:
- a plurality of supplies of different highly pressurized gas coolants with different boiling temperatures at ambient pressure, said supplies of coolants including a primary coolant with a lowest boiling temperature and at least one secondary coolant with an inversion temperature that is above ambient temperature,a plurality of stages stacked one above the other in thermal isolation from each other, each stage including a thermally conductive material plate member with fluid passages formed therein, the fluid passages in each stage including two-phase reservoir passages associated with a different coolant from reservoir passages in the other stages and a restricting passageway in fluid communication with the high pressure gas supply of that associated coolant, said restricting passageway forming a Joule-Thomson throttle valve opening into said reservoir passages for isenthalpic expansion and liquefaction of the associated coolant, said reservoir passages of a coldest stage associated with said primary coolant being in heat exchange relation with a cold surface of that coldest stage, said cold surface adapted for mounting a device to be cooled thereto in thermal contact therewith, each stage other than said coldest stage also having high pressure coolant supply passages in heat exchange relation with said reservoir passages of that stage for precooling each gas coolant with a lower boiling temperature than the coolant associated with that stage.
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Accused Products
Abstract
A stacked multistage Joule-Thomson (J-T) cryostat is described in which each stage comprises a thermally conducting material plate member with fluid passages formed therein and in which the stages are stacked one above the other but separated from each other by thermally insulating standoff supports. Each successive stage in the stack is cooled to successively lower temperature zones by J-T expansion and liquefaction of different coolant gases. Each stage has a restricting passageway connected to a different high pressure gas coolant supply and forming a throttle valve opening into two-phase (liquid-vapor) coolant reservoir passages. The reservoir passages in all but the coldest stage are in heat exchange relation with the high pressure supply passages of the lower boiling temperature coolant gases. The coldest stage is in heat exchange relation with a cold surface on which a device to be cooled can be mounted. Because the stages are constructed of thermally conductive material, there is substantially no thermal gradient within a given stage, and because the stages are thermally isolated from each other, substantial parasitic loads by the heat exchanger section on the cold reservoir for a given coolant is avoided.
58 Citations
28 Claims
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1. A stacked multistage Joule-Thomson cryostat, comprising:
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a plurality of supplies of different highly pressurized gas coolants with different boiling temperatures at ambient pressure, said supplies of coolants including a primary coolant with a lowest boiling temperature and at least one secondary coolant with an inversion temperature that is above ambient temperature, a plurality of stages stacked one above the other in thermal isolation from each other, each stage including a thermally conductive material plate member with fluid passages formed therein, the fluid passages in each stage including two-phase reservoir passages associated with a different coolant from reservoir passages in the other stages and a restricting passageway in fluid communication with the high pressure gas supply of that associated coolant, said restricting passageway forming a Joule-Thomson throttle valve opening into said reservoir passages for isenthalpic expansion and liquefaction of the associated coolant, said reservoir passages of a coldest stage associated with said primary coolant being in heat exchange relation with a cold surface of that coldest stage, said cold surface adapted for mounting a device to be cooled thereto in thermal contact therewith, each stage other than said coldest stage also having high pressure coolant supply passages in heat exchange relation with said reservoir passages of that stage for precooling each gas coolant with a lower boiling temperature than the coolant associated with that stage. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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8. A stacked two-stage Joule-Thomson cryostat, comprising:
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a supply of high pressure, primary coolant gas, a supply of high pressure, secondary coolant gas, said secondary coolant gas characterized by an inversion temperature that is above ambient temperature and by a boiling temperature at ambient pressure that is less than an inversion temperature of said primary coolant gas, a first stage including a thermally conductive material plate member with fluid passages formed therein, said fluid passages including a high pressure primary coolant supply path with an inlet connected to said supply of high pressure primary coolant gas and with an outlet, a low pressure primary coolant return path with an inlet and an outlet, and a secondary coolant path with an inlet connected to said supply of high pressure secondary coolant gas and with an outlet, said secondary coolant path including a flow restricting passageway forming a throttle valve opening into a secondary coolant reservoir in heat exchange relation with said high pressure primary coolant supply path, and a second stage, thermally isolated from said first stage and stacked above said first stage, including a thermally conductive material plate member with fluid passages formed there, said fluid passages including a primary coolant path with an inlet connected to said outlet of said high pressure primary coolant supply path of said first stage and with an outlet connected to said inlet of said low pressure primary coolant return path of said first stage, said primary coolant path in said second stage including a flow restricting passageway forming a throttle valve for said primary coolant gas opening into a primary coolant reservoir in heat exchange relation with a cold surface of said second stage, said cold surface adapted for mounting a device to be cooled thereto in thermal contact with said cold surface. - View Dependent Claims (9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A stacked three-stage Joule-Thomson cryostat, comprising:
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a supply of high pressure, primary coolant gas, a supply of high pressure, secondary coolant gas, said secondary coolant gas characterized by a boiling temperature at ambient pressure that is less than an inversion temperature of said primary coolant gas, a supply of high pressure, auxiliary coolant gas, said auxiliary coolant gas characterized by an inversion temperature that is above ambient temperature and by a boiling temperature at ambient pressure that is less than an inversion temperature of said secondary coolant gas, a first stage including a thermally conductive plate member with fluid passages formed therein, said fluid passages including a first high pressure primary coolant supply path with an inlet connected to said supply of high pressure primary coolant gas and with an outlet, a high-pressure secondary coolant supply path with an inlet connected to said supply of high pressure secondary coolant gas and with an outlet, a low pressure secondary coolant return path with an inlet and an outlet, and an auxiliary coolant path with an inlet connected to said supply of high pressure auxiliary coolant gas and with an outlet, said auxiliary coolant path including a flow restricting passageway forming a throttle valve for said auxiliary coolant gas opening into an auxiliary coolant reservoir in heat exchange relation with said high pressure, primary and secondary, coolant supply paths, a second stage, thermally isolated from said first stage and stacked above said first stage, including a thermally conductive material plate member with fluid passages formed therein, said fluid passages including a second high pressure primary coolant supply path with an inlet connected to said outlet of said first high pressure primary coolant supply path of said firs stage and with an outlet, a secondary coolant path with an inlet connected to said outlet of said high pressure secondary coolant supply path of said first stage and with an outlet connected to said inlet, said low pressure secondary coolant return path of said first stage, and a low pressure primary coolant return path with an inlet and an outlet, said secondary coolant path in said second stage including a flow restricting passageway forming a throttle valve for said secondary coolant gas opening into a secondary coolant reservoir in heat exchange relation with said second high pressure primary coolant supply path of said second stage, and a third stage, thermally isolated from said second stage and stacked above said second stage, including a thermally conductive material plate member with fluid passages formed therein, said fluid passages including a primary coolant path with an inlet connected to said outlet of said second high pressure primary coolant supply path of said second stage and with an outlet connected to said inlet of said low pressure primary coolant return path of said second stage, said primary coolant path in said third stage including a flow restricting passageway forming a throttle valve for said primary coolant gas opening into a primary coolant reservoir in heat exchange relation with a cold surface of said third stage, said cold surface adapted for mounting a device to be cooled thereto in thermal contact with said cold surface. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28)
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Specification