Abstract: A bread cooling machine comprising at least one carousel mounted for rotation about a central axis and having a number of stations about the periphery of the carousel. The stations are each arranged to support one or more loaves and cooling operations are carried out on the loaves during rotation of the carousel. The means for carrying out these cooling operations comprises hollow needles arranged to penetrate the interior of the loaves and to supply air under pressure thereto to cause a flow of cooling air from the interior of the loaves to the ambient atmospheric pressure exterior. There are conveyor means for delivering loaves to be cooled from an oven for example to the carousel stations and for receiving loaves after the cooling operations from the carousel for further processing stages such as slicing and wrapping of the loaves.

Abstract: A refrigerating apparatus is provided which comprises a cabinet (1) with a refrigeration compartment (10) closable by a door (12), which compartment is connected to an evacuating system comprising a vacuum pump (6) arranged in the cabinet and an evacuation pipe (8) between the vacuum pump and said compartment. The apparatus comprises a container (17) closable in a vacuum-tight manner and movable within said compartment (10), and means for detachably connecting the inner space of the container (17) with the pipe (8) of the evacuating system. The means comprise a container pipe (23) provided in a wall (24) of the container (17) through which the inner space of the container can be evacuated, and a hollow elastic element (25) connected to one of the ends of the pipes (8,23) facing each other to form a detachable seal against the other end.

Abstract: In a vacuum cooling apparatus, a hollow receptacle is provided, for containing a plurality of containers for containing materials to be cooled, the containers being slidably fitted in the receptacle one after another. The receptacle has through-holes formed therein at intervals corresponding to the dimension of the container which is measured in the axial direction of the receptacle in such a manner that the receptacle through-holes are arranged in the axial direction of the receptacle. Each of the containers has a container through-hole formed therein so that the container through-hole is allowed to communicate with the receptacle through-holes. Seal members also are provided, allowing the inside of each container to communicate with the outside only through the receptacle through-hole and container through hole.

Abstract: A cryogenic sorption pump comprises a housing complete with a cover, a bottom, and an inlet nozzle, and, a vessel for cryogenic agent, designed in the form of two shells installed in the central part of the pump one over the other and interconnected by a circular element. The cryogenic agnet vessel is provided with a heat conductor encompassing the upper shell and forming an interspace therewith, wherein is installed a gas-permeable screen. Between the heat conductor and the gas-permeable screen is located an adsorbent. The pump contains a vacuum conductor arranged within the space of the cryogenic agent vessel and provided with heat conductors attached to the vacuum conductor and installed inside the shells, respectively, throughout their length. The ends of the vacuum conductor are provided with heat bridges, respectively, and taken out of the housing through the bottom. The pump is also provided with pipes and for filling in cryogenic agent and removing cryogenic agent vepors, respectively.

Abstract: A cryogenic sorption pump including a pumping element complete with a vessel for a lower temperature cryogenic agent, a radiation screen encompassing the pumping element, a pipe, and a heat bridge. The radiation screen incorporates a vessel for a higher temperature cryogenic agent, a shell having its lower end connected to said vessel and its upper end, to the pump housing, and a chevron screen. The heat bridge is installed between the shell and the pumping element and has its upper end connected to the shell and its lower end to the vessel of the pumping element. The pipe passes within the space defined by the inner walls of the vessels and has its lower end connected to the bottom of the housing and its upper end to the vessel of the pumping element.

Abstract: The cryogenic condensation pump comprises a housing (3), accommodating a vessel (3) for a cryoagent, namely liquid nitrogen, a shell heat line and a chevron baffle which make up a radiation shield, and a pump-out element. The cryoagent vessel and pump-out element are provided with suspension pipes. Each of the suspension pipes is provided with assemblies, for joining it to the housing, and assemblies for joining it to the cryoagent vessel and the pump-out element.The suspension pipe of the pump-out element is provided with a support bush, and in the cover of the cryoagent vessel an annular element is secured which makes contact with the support bush. The pump housing, radiation shield and pump-out element are made of metals having low specific weight.

Abstract: The present invention relates to a cryopump with multiple cooling sufaces, each cooled independently by a closed-cycle refrigerator. Specifically, a primary pumping surface is cooled by a first, two-stage refrigerator independently from the radiation shield, which is cooled by a second, single-stage refrigerator.

Abstract: This invention relates to an apparatus and method for distillation drying of one or more biological samples. The drying apparatus includes a retaining assembly, a vacuum assembly, cooling means, monitoring means and control means for actively regulating the temperature and pressure conditions of biological tissue so that such tissue may be dried without substantial ultrastructural damage.

Abstract: A cold exchange system includes a Dewar flask having an inner vessel and an exterior vessel joined to and surrounding the inner vessel, defining an evacuable chamber therebetween. The flask includes an evacuation port through the inner and exterior vessels through which cryogenic gas contained in the inner vessel can evaporate during the cold exchange process. The exterior vessel includes a device port through which a device to be cooled extends. The device is housed in a housing that is engaged over the device port. A cold finger is in heat transfer contact with the inner vessel. A non-metallic flexible bellows is sealingly adhered to the cold finger at one open end of the bellows. The other open end of the non-metallic bellows is sealingly adhered at its other open end to a top plate which is vacuum fitted over the device port. The non-metallic bellows and device housing define a second evacuable chamber separate from the Dewar flask vacuum chamber.

Abstract: The invention discloses a cryopump comprising a primary cryopanel 67 associated with a low temperature heat sink 60 having means for adsorbing a first low boiling point gas and a secondary cryopanel 80 associated with heat sink 60 and a higher temperature heat sink 48 having means for condensing a higher boiling point gas. There are means 90 for selectively irradiating the primary cryopanel from a location external to the vacuum chamber. The radiation raises the temperature of the cryopanel above that which is necessary to cause said first gas to become desorbed from said cryopanel while having minimal effect on the capacity of the higher temperature heat sink.

Abstract: A regenerable cryosorption pump with a movable physical barrier in which the barrier includes a cylindrical body closed at one end and having a circumferential baffle around the open end. The baffle engages a flange on the hydrogen isotope condensing and pumping surface to require all gases entering the pump during normal operation to pass through the hydrogen isotope condensing and pumping surface, thus avoiding bypass of that surface. The barrier is advanced by a bellows system to isolate the hydrogen isotope condensing and pumping surface from the sorbent surface during regeneration and thus ensuring separation of hydrogen isotopes such as tritium from helium which is sorbed onto the sorbent surface.

Abstract: A cryopump which has three temperature stages for pumping gas. The third temperature stage is surrounded by and separated from the second temperature stage which is surrounded by and separated from the first temperature stage. Adsorbent placed on the second and third stage are operated at different temperatures to prevent gases with higher critical mobility temperatures from becoming immobilized at the entrance of pores and wells along the surface of the adsorbent.

Abstract: The invention relates to a process for the simultaneous exchange of heat and matter through a porous wall. A relatively hot gaseous mixture of two constituents passes through an exchange compartment by flowing along the first surface of a porous wall and is progressively cooled, which causes the condensation of a fraction of said mixture. This fraction is vaporized on the second surface of the wall in contact with a relatively cold gas. This process is useful for the fractionation of a mixture of two constituents of a gas, for example, of a mixture of pentane and heptane.

Abstract: Herein disclosed is a cooling system for use with an internal combustion engine which is operated on evaporable fuel supplied from a fuel tank. The cooling system comprises a tube extending from the fuel tank to a venturi throat portion of an air induction passage of the engine, an expansion valve connected to the tube and opening the tube when a pressure in the tube downstream of the valve is reduced to a certain degree, an evaporator device connected to the tube at a position downstream of the expansion valve, and a structure for defining an enclosed space about the evaporator device.

Abstract: In a vacuum system having a load lock cooperating with a work chamber, a flow line is connected between the cryopump of the load lock and the work chamber. The flow line passes noncondensible gases which are not absorbed by the cryopump of the load lock to the work chamber 12 for absorption by the cryopump of the work chamber. Alternatively, the flow line is connected between the load lock cryopump and the cryopump of the work chamber for directly passing the noncondensible gases to the work chamber cryopump. The flow line prevents buildup of noncondensible gases within the cryopump of the load lock. The flow line may include baffles to damp pressure surges during cryopumping of the load lock. A control valve connected to the flow line allows operator control of the passing of noncondensible gases from the load lock cryopump to the work chamber or to the work chamber cryopump through the flow line. The dimensions of the flow line provide molecular flow of the noncondensible gases.

Abstract: Ice is formed by allowing water to partially evaporate in a vacuum. The ice can then be removed and be collected for subsequent use. For the creation of the vacuum, means for reduction of the pressure are required. A vapor compressor may be used for suction and compression of the water vapor to a pressure which enables condensing on a cold surface without freezing occurring. To be able to manufacture ice in a vacuum without using an expensive water vapor compressor, a method and a device for the manufacture of an ice slurry include which several cooperating vacuum chambers (1, 2, 3) with cold surfaces (6, 7, 8) used in a plant without a water vapor compressor. In this plant fresh water is supplied to one of the vacuum chambers for defrosting thereof, the thermal energy of the fresh water being utilized for that purpose. The precooled water thus formed is supplied to the other vacuum chambers, in which they will then form ice.

Abstract: An improved cryopump for the removal of gases from a high vacuum, comprising a cryopanel incorporating honeycomb structure, refrigerant means thermally connected to the cryopanel, and a rotatable channel moving azimuthally around an axis located near the center of the cryopanel, removing gases absorbed within the honeycomb structure by subliming them and conducting them outside the vacuum vessel.

Abstract: A two stage cryopump with an improved first stage for condensing water vapor at high speed independently of the rate of gas flow into the second stage and without increasing the heat load on the cryopump. The cryopump utilizes a low profile high precision variable aperture to control flow to a lower baffle obstructing the mouth of a shroud containing the second stage, utilizes a support shaft mounted on the top of the lower baffle and extending upstream through the aperture, and utilizes an upper baffle mounted on the top of the shaft in thermal contact with the lower baffle to condense water vapor before reaching the aperture.

Abstract: A throttle valve with a separate flange, usable with a vacuum pump defining an inlet opening, and a controllable throttle assembly for varying a flow passage cross section of the inlet opening. The throttle assembly is disposed in the inlet opening and has a plurality of slats rotatable about respective longitudinal axes for varying their inclination and an actuating rod for turning the slats. The flange has a throughgoing bore through which the actuating rod passes. The slats have a substantially constant width and their longitudinal axes are oriented parallel to one another. The slats form a first and a second slat group, and a linkage connects the slats with one another for turning the slats of the first slat group and the slats of the second slat group in opposite directions. A chamber is situated externally of the inlet opening and communicates with the throughgoing bore. A pivotal lever articulated to the actuating rod is situated in the chamber and projects outwardly therefrom.

Abstract: A refrigerant fluid trap for a vacuum evaporator for depositing a thin metal film including a U-shaped structure for passage of refrigerant fluid, forming an interior space for trapping condensable vapors. In said interior space there is housed a titanium evaporation source.

Abstract: A method for cooling a material in contact with a cooling medium comprises evaporating water contained in the cooling medium and adsorbing the evaporated water to soft burnt lime and causing the evaporation and the adsorption to be carried out under a reduced pressure to cool the material. An apparatus for carrying out the method is provided.

Abstract: The refrigerator of a cryopump is positioned within an insulating vacuum and the two stages of the refrigerator are selectively thermally coupled to first and second stage cryopanels. After initial rough pumping by an air ejector, rough pumping is completed during startup by coupling the cold first stage of the refrigerator to a first stage adsorption cryopanel. The second stage of the refrigerator is thereafter coupled to the second stage cryopanel. Thermal coupling of the refrigerator to the cryopanels is by means of spring biased thermal contacts brought into position by movement of the refrigerator. The thermal contact elements are provided with sufficiently large thermal masses to handle the large thermal loads of system startup.

Abstract: An evaporating apparatus comprising a high temperature side evaporator and a low temperature side evaporator connected in series in a flowing direction of a heat source, a first and second pipe line for directing fluid being evaporated therethrough, and an ejector having a suction inlet and a discharge outlet of drive steam and an induction port of steam being sucked, wherein the first pipe line is linked through the high temperature side evaporator to the suction inlet of the ejector, and the second pipe line is branched from the first pipe line at the upstream side of the hot temperature side evaporator, and linked through the low temperature side evaporator to the induction port of the ejector.

Abstract: A refrigerator or heat pump with a jet pump (1) as the compressor, in which the evaporator (2) of the heat-pump or refrigerator circuit is incorporated in the jet pump (1). In the simplest case, this is achieved by the presence, in the inlet line, of a partition (18, 39, 40, 41) made of porous material such as, for example, sintered metal, which firstly exercises a throttling action between the condenser pressure and the evaporation pressure and secondly on whose large internal surface the evaporation of the working medium takes place at the same time. The supply of the evaporation heat is obtained by the fact that only one part of the liquid working medium fed from the condenser (3) is evaporated, and on the other hand heat can be supplied from outside via heat-exchangers (21, 27). Heat-pump or refrigerator circuits with a jet pump of this type (1, 24, 30) can also be designed with several stages, so that an internal heat exchange can be effected in a number of ways.

Abstract: A vibration isolated cryogenic apparatus mounted as a mass in a series of mass/elastomer/mass springed system.

Abstract: A high throughput continuous cryopump is provided. The cryopump (10) incorporates an improved method for regenerating the cryopumping surface (22) while the pump is in continuous operation. The regeneration of the cryopumping surface (22) does not thermally cycle the pump, and to this end a small chamber (91) connected to a secondary pumping source (60) serves to contain and exhaust frost removed from the cryopumping surface (22) during such regeneration. The frost is exhausted at a rate substantially independent of the speed of the cryopump which enhances the capability of the pump to achieve a high compression ratio and allow the pump to operate continuously while the cryopumping surface is being regenerated.

Abstract: High vacuum pumping system employs a poppet valve having dual seats for respectively seating a pair of vertically disposed spaced valve discs thereon to define a closed position. A refrigerated cold trap is located within a dome portion of the valve, i.e., above the upper of the valve discs while seated, and a diffusion pump is mounted below the valve to evacuate the vacuum process chamber when the discs are elevated or unseated to define an open position. The cold trap and diffusion pump are mounted in parallel and form a common axis with the poppet valve thereinbetween. Means are provided to equalize the pressures within the dome and vacuum process chamber when the discs are seated.

Abstract: The pressure relief valve is debris resistant, self-cleaning, and self-actuating in a cryopump. It includes an o-ring carried by a valve member within a valve cylinder. In opening, the valve member moves away from an end port to open vent ports in the side of the valve cylinder while withdrawing the o-ring to a debris free and protected region of the valve. As the valve member is moved into the closed position in response to an atmospherical pressure differential, a wiper ring cleans debris from the inner surface of the valve cylinder. A taper is provided on the inner surface of the cylinder to release compression on the vacuum sealing o-ring upon opening and to compress the o-ring as the valve member moves to the closed position. The wiper ring is expansible in order to provide a wiping action along the entire taper and prevent debris from reaching the o-ring. The end of the valve cylinder opposite to the end port serves as a shock absorber as the valve is opened.

Abstract: A cryopump with quicker adsorption of non-condensible gases is disclosed. The second stage cryopanel of this cryopump is comprised of an array of discs spaced along an axis perpendicular to the frontal cryopanel, and in close thermal contact with the second stage heat sink. Each disc of the array is bent toward the frontal cryopanel at the outer edge of the disc and is flat radially inward from the bend. Each disc is coated with adsorbent material on the surface away from the frontal cryopanel radially inward from the bend in the disc.

Abstract: A cryopump is regenerated by means of an ejector pump which draws gas from the cryopump as the pump is warmed. The ejector is actuated by an inert gas. The same inert gas may also be used to purge the pump during evacuation.

Abstract: Method and equipment for the utilization of the freezing heat contained in water as a source of heat of a heat pump. The water flow to be utilized as the source of heat is evaporated in one or several stages (4) at such a low pressure that, when the vapor that is formed binds its evaporation heat out of the water, part of the water freezes. The vapor formed is condensed in one or several heat exchangers functioning as the evaporator of the heat pump, whereat the vapor, on being condensed, delivers its heat to the heat transfer medium used in the heat pump.

Abstract: A cryogenic pump with a two stages refrigerator, an access grid and condensation walls partially coated by adsorbing material and thermally connected to the second stage of the cryogenic generator, which walls are formed by one or more metallic strips so shaped as to slant considerably in respect to the axis of the cylindrical shield and completely covered by an adsorbing material on both faces; said walls are protected by shielding surfaces at least outside reflecting.

Abstract: The hypobaric preservation of respiring plant matter without the step of humidifying the storage atmosphere by contacting it with a supplementary body of heated water is hereby disclosed, characterized by storage at controlled and correlated conditions of temperature, subatmospheric pressure, evacuation rate, air recirculation rate and air intake rate, and by the dependence of each set of correlated conditions upon the weight, respiration rate and type of plant matter. Expanded relatively dry atmospheric air is passed into and humid rarified air is withdrawn from the storage chamber at rates which maintain an optimal steady-state oxygen partial pressure for each type of respiring, oxygen-consuming plant matter, and a nearly saturated relative humidity sufficient to keep the temperature of the respiring, heat producing plant matter equal to or slightly higher than the temperature of the chamber walls and rarified air.

Abstract: To control the temperature of one or more heat sinks of a cryogenic refrigerator in a cryopump, refrigerant gas to the refrigerator is diverted through heat exchangers associated with the refrigerator heat sinks. The diverted refrigerant gas may be used to maintain the temperature of the first stage cryopumping surfaces above some level to avoid cross over hangup. The second stage cryopumping surfaces may be warmed by the diverted refrigerant to some temperature level for partial regeneration. Both heat sinks may be warmed for full regeneration of the cryopump. Bleed flow of refrigerant gas cooled by the first stage of the refrigerator can be directed past a thermal mass to cool that mass. By reversing the flow of refrigerant gas during cooldown of the system, the thermal mass can be used to more rapidly cool the refrigerator. The thermal mass is thermally isolated from the refrigerator heat sinks and is positioned within the vacuum vessel of the cryopump adjacent to the first stage of the refrigerator.

Abstract: A cooling heat exchanger such as a cold trap for removing contaminants from a vapor stream. Vapor flows through a conduit having angled baffles therein. The baffles are aligned within the conduit so as to form an optically dense trap. A cold region is created by placing a cold finger of a cryogenic refrigerator in contact with a sleeve surrounding the conduit adjacent to the baffles. Insulation of the cold region to maintain cryogenic temperatures is accomplished by insulation within an insulating container surrounding the cold region.

Abstract: A cryopump and a method of operating the same, with the cryopump being provided with a cryopanel adapted to be cooled with cold heat generated by a cold heat generating device, and remove the ambient gas, and a device for regulating the temperature of said cryopanel in accordance with the ambient conditions. The cryopump is capable of varying its pumping speed by regulating in accordance with the ambient conditions the temperature of the cryopanel which is adapted to be cooled with cold heat and remove the ambient gas.

Abstract: The apparatus comprises an insulated storage tank adapted to hold a liquified cryogenic fluid and vapor emanating from the liquified cryogenic fluid, an insulated working chamber adapted to hold an object to be treated, and a vacuum pump for evacuating the interior of the working chamber. The storage tank is in fluid communication with the working chamber, either directly, or through a vapor reservoir adapted to hold the vapor emanating from the cryogenic fluid. The method comprises introducing the vapor and/or liquid cryogen into the working chamber either in discrete or continuous amounts. The working chamber can be evacuated to a specific negative pressure either prior to introducing the vapor and/or liquid cryogen or simultaneously as the cryogens are introduced. The apparatus also provides the capability of heating materials from cryogenic levels to room-or-higher-temperature levels in a choice of ambient gases.

Abstract: An exhaust port from a cryopump vacuum vessel leads to an exhaust valve. The valve is protected from contamination by a filter standpipe which extends from the exhaust port into the vacuum vessel and which is open at its end opposite to the exhaust port. The standpipe is of porous material which allows the free flow of gas, water, and liquid cryogens therethrough while retaining contaminating debris within the vacuum vessel. The filter conduit is of screen formed into a cylinder. One end is tapered and pressed into the exhaust conduit. The screen cylinder is stopped in the exhaust conduit by a circumferential ridge.

Abstract: The hypobaric preservation of non-respiring animal matter without the step of adding fresh air to the storage chamber, and without humidifying the storage atmosphere by contacting it with a supplementary body of heated water, is hereby disclosed, characterized by storage at a controlled temperature correlated to the type of animal matter, by a hypobaric pressure slightly less than the vapor pressure of water at said storage temperature, and by evacuation at a controlled rate correlated to the storage temperature and the weight of stored animal matter. The evacuation rate preferably is set to pump nearly saturated steam from the vacuum tank at a rate which exhausts an amount of water equal to about 1% of the initial weight of the animal matter each month.

Abstract: A heat pump using water as a refrigerant comprises an evaporator equipped with a feedwater control device and a draining device, a compressor and a condenser equipped with a vacuum generating means.

Abstract: Apparatus for providing a simulated space environment for the testing of articles under low temperature conditions comprising a liquid nitrogen head tank, liquid nitrogen subcooler pumps, a liquid nitrogen subcooler coil, a liquid nitrogen head tank makeup pumps, a low pressure liquid nitrogen storage tank, a high pressure liquid nitrogen storage tank, a liquid nitrogen transfer pump, a vacuum chamber and thermal simulation heat exchanger shrouds contained within the vacuum chamber. Appropriate internal and external piping connects these components so that the apparatus can be operated both in a subcooled pressurized closed loop system as well as in a gravity convection system. While liquid nitrogen in this apparatus will produce a stable uniform temperature of -297.degree. F. within the shroud containing the article to be tested, other liquids with similar low temperature characteristics may be used.

Abstract: An apparatus and method for vacuum cooling produce and similar foodstuffs includes a vacuum cooling chamber, a vacuum pump, refrigeration equipment and data processing equipment which is provided with various data by the operator, weight and pressure sensors within the cooling chamber and appropriately controls and terminates the operating cycle of the equipment. The method generally includes determining the initial weight and average temperature of the produce, calculating the amount of heat removal necessary to lower the temperature of the produce to a predetermined final temperature, calculating the amount of water to be removed to accomplish the desired heat removal and subjecting such produce to a vacuum to vaporize the quantity of water from such produce, such quantity of water having a heat of vaporization sufficient to achieve the previously calculated heat removal.

Abstract: A cryopump has a two-stage refrigerator in a housing with a pumping surface area in thermal communication with each stage of the refrigerator for gas-pumping by adsorption or absorption when the refrigerator is operated. A roughing vacuum pump provides a pressure of from about 1 to about 10.sup.-3 mbar to the housing and at least the pumping surface area of the second refrigerator stage is heated sufficiently to prevent gas adsorption or absorption thereon before the cryopump is operatively connected to a space to be evacuated therewith as a starting method for improving the cryopumping of, particularly, helium and a regenerating method after use of the cryopump.

Abstract: Orifices in a cooled plate throttle gases entering a cryopump. Selected orifices are closed by removable closures such as spring clips to allow the throttling to be varied.

Abstract: The invention relates to a method for treating moist pulverulent material and is particularly useful for removing the moisture from such material. In one aspect of the invention, the material is hot foundry sand, where the sand is first moistened by the addition of water and then the moist sand is treated in a vibrating container under vacuum.

Abstract: A vacuum cooling trap for use in a vacuum chamber comprising: a laminated structure comprised of a pair of plates bonded together in face-to-face contacting relation, the plates being composed of metal of high thermal conductivity, and the plates having aligned confronting conduit portions which jointly define a conduit within the laminated structure for circulating a cooling medium through the laminated structure during use of the vacuum cooling trap.

Abstract: A cryosorption pump for high vacuum condition to be evacuated generally comprises a cryopumping container connected to a chamber to be evacuated, and cryosorption and cryocondensation members located in the container. The cryocondensation member surrounds the cryosorption member on which an adsorbent is applied to adsorb gases which are not beforehand condensed on the cryocondensation member. A coil means or magnet means for generating a magnetic field is also disposed in the container so as to generate a magnetic field around the cryosorption member to prevent from the impingement of energetic electrons or .beta.-rays emitted from a material condensed on the cryocondensation member against the cryosorption member.

Abstract: A reactor for performing reactions at very low, i.e. cryogenic temperatures has a collection vessel mounted above an electron gun to collect vaporized material such as metals, metal oxides, metal salts and metal halides. The collection vessel is maintained at a very low temperature, typically between 14.degree. and 77.degree. K., by a heat pump that also serves as a support for the collection vessel. A manifold introduces a reagent into the reactor between the electron gun and the vessel to react with the vaporized material and form a product. The product is condensed on the collection vessel which may then be inverted to provide a stable support for the collected product during further experimentation.

Abstract: The disclosure relates to a refrigeration system wherein the evaporator of the refrigeration system is placed within a vacuum system as a "Meissner" coil previously described. Optionally it may be provided with extended surface(s). The cryosurface has a single tube passage for flow of either an evaporating low temperature refrigerant fluid for cooldown and continuous cold operation, or superheated compressed refrigerant gas for adding heat during the defrost cycle. Appropriate valves select whether cold fluid or superheated refrigerant gas flows through the tube in the cryosurface. A recuperative heat exchanger and a superheating exchanger preheat, in two stages, a cold compressed refrigerant gas stream after the gas has been rectified within the system. This superheated gas stream defrosts the cryosurface, flows back through the recuperative heat exchanger where it is recooled and then is reintroduced into the cold cascade heat exchangers.

Abstract: A cryopump and method for using cryopumping to enhance the sensitivity of a leak detection system. The cryopump is used to control the relative pumping speeds of the gases normally frozen out on the pump or adsorbed in a cold adsorbent to thereby achieve the enhanced sensitivity of the system. The system is characterized by controlled access to the cold panel which is disposed within the warm panel.