Abstract: Methods and apparatus for partial regeneration of a cryopump are provided. The cyropump includes first and second stage cryoarrays, a refrigerator for cooling the first and second stage cryoarrays, and typically includes a sorbent material for removing gases by cryosorption. The second stage cryoarray is heated from its operating temperature to a partial regeneration temperature range selected to liberate captured gas from the second stage cryoarray and to retain condensed water vapor on the first stage cryoarray. The partial regeneration temperature range is preferably 100K to 160K and is more preferably 120K to 140K. When the second stage cryoarray has a temperature within the partial regeneration temperature range, gas liberated from the second stage cryoarray is pumped with a turbomolecular pump in fluid communication with the cryopump. The turbomolecular pump removes liberated gases from the cryopump at high speeds and produces a low pressure in the cryopump.

Abstract: A cryogenic pump capable of operating with a sub-zero net positive suction head includes a reciprocating piston positioned in a cylindrical housing for dividing the interior of the housing into a supercharger chamber and an evacuation chamber on opposite sides of the piston. A supercharger chamber valve, positioned directly behind the reciprocating piston, controls the flow of liquified gas from a gas inlet into the supercharger chamber. A fixed piston, extending into the evacuation chamber, engages a cylindrical skirt carried by the reciprocating piston to form a high pressure chamber between the two pistons. Liquified case from the high pressure chamber is supplied to a gas outlet via a passageway in the fixed piston.

Abstract: A cryogenically cooled water pump traps water vapor with a high probability but is open to non-condensing gases for high conductance to a turbomolecular pump. The preferred array is a single cylinder, having a length to diameter ratio of between 0.5 and 1, concentric with and near to an ambient temperature conduit. A center baffle, preferably of closed frustoconical shape, may be positioned at the center of the array over the upper bearing plate of the turbomolecular pump where it results in minimal reduction in conductance to the pump.

Abstract: A system has been developed for adsorbing gases at high vacuum in a closed area. The system utilizes large surface clean anodized metal surfaces at low temperatures to adsorb the gases. The large surface clean anodized metal is referred to as a metal sponge. The metal sponge generates or maintains the high vacuum by increasing the available active cryosorbing surface area.

Abstract: The invention relates to a cryopump operated with a refrigerator, having a housing, having an inlet valve, having heatable pumping surfaces and having a backing pump connected to the pump interior; to be able to regenerate the cryopump quickly by executing the removal of the condensed gases at a high pressure, it is proposed that it is equipped with a line for the precipitates to be removed and that is provided with a regeneration valve.

Abstract: A cryopump array is described. Each vane of the array is coated with a 3-dimensional adsorbing structure made up of an adhesive which is transparent to passage of gases to be pumped by adsorption and a plurality of pieces of an appropriate adsorbing material adhered on top of one another.

Abstract: Fluid transfer apparatus comprising a fluid reservoir and a pump connected to the reservoir by a supply line, wherein the apparatus is configured so that vapor generated in the pump during periods of inoperation may escape from the pump cavity through the pump inlet, rather than being trapped in the pump cavity, and liquid may flow into the pump cavity from the supply line through the pump inlet to replace escaping vapor, thereby providing reliable pump start-up during intermittent operation. The apparatus may be employed to pump LNG for fueling of vehicles. Where LNG or another cryogenic fluid is being pumped, the pump is preferably driven by a motor located above the pump and connected thereto by an elongated shaft. Shaft seals may be provided to prevent the fluid being pumped from contacting the motor or the bearings supporting the motor shaft. A vapor trap may be provided beneath the shaft seals to prevent contact between liquid being pumped and the shaft seals.

Abstract: Cryogenic fluid piston pump functions as stationary dispensing pump, mobile vehicle fuel pump etc., and can pump vapour and liquid efficiently even at negative feed pressures, thus permitting pump location outside a liquid container. Piston inducts fluid by removing vapour from liquid in an inlet conduit faster than the liquid therein can vaporize by absorbing heat, and moves at essentially constant velocity throughout an induction stroke to generate an essentially steady state induction flow with negligible restriction of flow through an inlet port. Stroke displacement volume is at least two orders of magnitude greater than residual or dead volume remaining in cylinder during stroke changeover, and is greater than volume of inlet conduit. Cryogenic tank has a liquid compartment, a vapour compartment, and inlet and overflow conduits. Inlet conduit receives liquid from dispensing pump and widely disperses liquid into liquid tank to contact and condense vapour.

Abstract: The invention relates to a process for regenerating a cryopump (1) that is equipped with an inlet valve (33), with cold surfaces (6, 8, 11) which have a temperature during operation of the pump that effects the condensation and/or adsorption of gases and which are heated for the purpose of regenerating them, the cryopump further including a backing pump (45) that is connected with the pump interior (9) by way of a valve (44). In this process, heating of the cold surfaces begins if the inlet valve (33) is closed and the connection between the pump interior (9) and the connected backing pump (45) is blocked so that, in addition to the temperature of the cold surfaces, the pressure in the pump interior also rises to values that lie above the corresponding values of the triple point of the gas to be removed.

Abstract: Apparatus and method for vacuum pumping an enclosed chamber includes a cryogenic pumping device in fluid communication with the chamber for removing gases from the chamber. The cryogenic pumping device includes a cooled pumping surface and an expander for expanding a compressed gas and thereby cooling the pumping surface. The vacuum pumping apparatus further includes a sensor for sensing an operating parameter, such as temperature, of the cryogenic pumping device and a controller responsive to the sensor for controlling the operating speed of the expander to produce a desired value of the operating parameter. Typically, the sensor is a temperature sensor, and the controller controls the speed of the expander motor.

Abstract: In a fast partial regeneration process, the second stage of a cryopump is heated as purge gas is applied to the cryopump. In a test loop, the purge gas is turned off and the roughing valve is opened. If the cryopump is judged to be sufficiently empty of gases from the second stage by being roughed to a sufficiently low pressure in a short period of time the system proceeds to a reconditioning phase. If the system fails the test, however, it is repurged with a burst of warm purge gas and then retested. After passing the emptiness test, the pressure is further reduced by the roughing pump as heat is applied to the second stage. The heat is then turned off for cool down as the system continues to be rough pumped to a base pressure. At about the base pressure, the roughing valve is cycled to maintain the cryopump pressure at a level near to the base pressure.

Abstract: Apparatus for vacuum pumping an enclosed chamber without the use of activated charcoal to remove hydrogen by cryosorption. As a result, the potential for contamination by a sorbent material is eliminated. The pumping structure includes an integral two-stage vacuum pump. The first-stage pump is a cryogenic pump having a pump chamber and cryoarrays mounted on an expander for cryocondensation of the principal gases present in the vacuum chamber. The second-stage pump operates at room temperatures and includes one or more getter pumps whose principal function is to remove hydrogen molecules that may be present in the vacuum chamber after the first-stage cryopump has removed most of the cryocondensable gases from the vacuum chamber. In one aspect of the invention, the first-stage pump is separated from the second-stage pump by a gate valve to protect the getter pumps during the regeneration flushing of nitrogen through the first-stage cryogenic pump chamber.

Abstract: A cryopump includes a housing in which is mounted a cooling head having a first, 80.degree. K. cooling stage and a second, 20.degree. K. cooling stage. A shield mounted on the cooling head surrounds the two stages, and a cooling surface within the housing and within the shield surrounds the second stage. The housing and the shield include corresponding inlet openings for admitting gases, and a diaphragm protects the cooling surface from heat radiation entering the inlet openings. The diaphragm is closer to the cooling surface than is the shield, creating a transfer opening that permits free access of gases into the volume within the shield. The cooling head can be rotated by an adjustment motor to displace the shield inlet opening with respect to the housing inlet opening to control the suction capacity of the pump for process gases without the need for an additional reduction valve, while maintaining the capacity for processing water vapor.

Abstract: A cryopump includes a sloped draining surface for receiving liquids released from cyropumping surfaces. The liquids are collected in an exhaust port and released outside the cryopump vacuum vessel. A pressure relief valve coupled to the exhaust port exhausts gases released by the pumping surfaces after warming. The cryopump further includes a drain filter assembly connected to the exhaust port for collecting debris and removing liquid that is released from the cryopumping surfaces. A purge gas tube facilitates the removal of large quantities of liquid in the cryopump.

Abstract: This invention relates to linear motor compressors which operate without the use of oil and a gas bearing while providing a flexible suspension for such a compressor. Such structures of this type, generally, provide a highly reliable oil-free compressor for use with cryogenic refrigeration equipment so as to attain unattended, continuous operation without maintenance over extended periods of time.

Abstract: In a cryopump a frost concentrating device is affixed to a condensing cryopanel and provides surfaces for condensing gases which are cryopumped through an opening in the vacuum vessel. The surfaces of the frost concentrator extend towards the opening in the vacuum vessel and thus limit the amount of gases which condense on the surfaces of the condensing cryopanel facing the opening. The result is that the gap between the radiation shield and the condensing cryopanel does not become significantly narrowed by condensing gases, particularly in the area closest to the opening through which gases are cryopumped. This allows other gases to pass easily through the gap and condense on surfaces of the condensing cryopanel further away from the opening of the cryopump or to be adsorbed by an adsorbent material shielded by the condensing cryopanel.

Abstract: A piston pump for conveying cryogenic fluids, especially liquid hydrogen, permits reliable transport of relatively large amounts of the fluid at high conveying pressures even with horizontal operation of the pump. The actual pump is inserted in an inner casing pipe (3, 25) of a vacuum housing. The pump is connected by a thread at one end of the housing and sealed against the atmosphere by an O-ring. The cylinder of the piston pump is sealed with respect to the inner casing pipe on the high-pressure side as well as on the low-pressure side by means of synthetic resin gaskets.

Abstract: A cold trap includes a set of baffles cooled by the cold finger of a closed cycle refrigerator. The baffles are vertically disposed in a vertical fluid conduit with frustoconical and conical surfaces for directing liquid to a circular trough during regeneration. After the liquid is collected, it is blown from the trough through a pressure relief valve by a nitrogen purge. The trough is formed in the upper surface of a connecting flange at the lower end of the fluid conduit.

Abstract: An evacuation system in an ultra-high vacuum sputtering apparatus capable of shortening the pumping time of the system. A main pump, composed of a turbo-molecular pump and a baffle is positioned upstream of a main pump and cooled to a temperature in which argon gas is not absorbed and only water is absorbed. The pump and a vacuum chamber are separated by a valve. A pipeline circulates a heating medium to rapidly heat and cool the vacuum chamber for enabling a gas discharge from the vacuum chamber whereby the pumping time can be reduced and the overall production of the system can be increased.

Abstract: To perform an even, high temperature baking treatment at about 450.degree. C. to a cryopump for the achievement of an extremely high vacuum, the cryopump is divided into two, a pump section P and a refrigerator R; the pump section P is cut off, with a vacuum state maintained, from the refrigerator R; and cooling stages 49 and 69 of the refrigerator R are connected through detachable heat transfer means 53 and 73 to cryopanel 2 and 5 of the pump section P, whereby the pump section P and the refrigerator R being detachably connected together. A drive unit of the refrigerator R and a casing 1 of the pump section P are connected together by a bellows 36, and at least a part of the transfer means 53, which connects the cooling stage 49 and 69 of the refrigerator R to the cryopanels 2 and 5 of the pump section P, made of a flexible material.

Abstract: Apparatus for vacuum pumping an enclosed chamber includes a cryopump in gas communication with the chamber for removing gases by cryocondensation and cryotrapping and an auxiliary pumping device for removing gases that are difficult to remove by cryocondensation or cryotrapping. The cryopump does not contain a sorbent material for cryosorption. As a result, the potential for contamination by a sorbent material is eliminated. The auxiliary pumping device can comprise an ion pump or a turbomolecular vacuum pump. When an ion pump is used, the ion pump is inactivated during periods of high gas loading in the chamber. The vacuum pumping apparatus is particularly useful for vacuum pumping of a plasma vapor deposition chamber.

Abstract: A cryopump includes a sloped draining surface for receiving liquids released from cyropumping surfaces. The liquids are collected in an exhaust port and released outside the cryopump vacuum vessel. A pressure relief valve coupled to the exhaust port exhausts gases released by the pumping surfaces after warming. The cryopump further includes a drain filter assembly connected to the exhaust port for collecting debris and removing liquid that is released from the cryopumping surfaces. A purge gas tube facilitates the removal of large quantities of liquid in the cryopump.

Abstract: Methods and apparatus for economically and effectively using a portion of a liquified compressed gas feedstock, such as liquid carbon dioxide, as a refrigerant to cool said liquified compressed gas feedstock so as to prevent cavitation and liquid compressibility when pumping such feedstock are disclosed.

Abstract: A cryopump is capable of pumping a process chamber at a process pressure and differentially pumping a second chamber such as an RGA independently at a substantially lower pressure. A member extends through the cryopump housing into a low pressure region disposed within the second stage array. The member comprises a port for accessing the low pressure region, thus providing an independent differential pumping source. No physical seal is required between the member and the main cryopump volume to maintain the pressure differential.

Abstract: A turbopump which operates at cryogenic temperatures to pump cryogenic liquid fuels to high pressure, and which includes a rotating group supported on process fluid foil journal bearings and a hydrostatic and hydrodynamic foil thrust bearing. A back-face surface of a pump rotor reacts thrust forces to the foil thrust bearing and receives counter acting hydrostatic fluid forces dynamically moderated to achieve an equilibrium axial position and force balance.

Abstract: In a cryostat vacuum chamber encompassing a refrigerator and a sample table cooled by the refrigerator, a heater is provided for controlling a temperature of the sample table, and the refrigerator is also provided with separate heaters.

Abstract: A network of cryopumps, each having an electronic regeneration controller, is coupled to a common rough pump. Each regeneration controller operates independently except that each is inhibited from opening its roughing valve to the common rough pump. Each regeneration controller only proceeds to open the roughing valve after it has received a token from a network interface terminal. The network interface terminal may control multiple groups of cryopumps coupled to respective common rough pumps. The regeneration controllers are removable modules connected to the cryopumps. A PROM is provided for each cryopump to the side of the connector opposite to the module. The PROM stores data specific to the cryopump and retains the data for the cryopump with replacement of the controller module.

Abstract: A cryogenic vacuum pump includes, in an integral assembly, temperature sensors and heaters associated with the first and second stages of the cryopumping array, a roughing valve and a purge valve. An electronic module removably coupled in the assembly responds to all sensors and controls all operations of the cryopump including regeneration thereof. System parameters are stored in a nonvolatile memory in the module. Included in the regeneration procedures are an auto-zero of the pressure gauge, heating of the array throughout rough pumping, and a change in pressure rate test to determine stall in rough pumping. The electronic module also restarts the system after power failure, limits use of a pressure gauge to safe conditions, provides warnings before allowing opening of the valves while the cryopump is operating and stores sensor calibration information. Control through a control pad on the pump may be limited by a password requirement. Password override is also provided.

Abstract: Condensation on a cryopump second stage refrigerator cylinder is prevented by arranging a passageway between a colder second stage cylinder shield in thermal contact with the coldest section of the second stage and a warmer radiation shield in thermal contact with the warmer first stage. This arrangement produces a uniform and significant temperature differential in the passageway. The passageway is arranged so that the ratio of its length, L, to its width, W, is ideally greater than five. This ensures molecular collisions with the cold surface of the cylinder shield so that gas molecules are tightly bound to the cylinder shield. As a result, condensation on the refrigerator cylinder and resultant pressure variations are prevented.

Abstract: A linear drive motor of a cryogenic refrigerator, where a reciprocating armature is coupled to a piston which alternately compresses and expands a gaseous fluid in a thermodynamic cycle. The piston has a clearance seal and is attached at one end to a flexible coupling to reduce cross-bearing loads exerted by the piston along the clearance seal. A displacer assembly of the cryogenic refrigerator employs a displacer piston that reciprocates along a clearance seal. The displacer piston is coupled to the displacer cylinder and/or the armature of a displacer drive motor by a flexible coupling that reduces radial forces exerted by the displacer piston on the clearance seal.

Abstract: A single horizontal cylinder, small refrigeration compressor has a lubrication arrangement which includes a recess on the cylinder block above the cylinder bore which collects oil that drains from the lower end of the motor. A supply passage extends downward from said recess and opens into the cylinder bore near its midpoint. The piston has an elongated shallow groove on the interior between head and skirt lands which is connected to the passage during a major portion of the piston stroke to receive oil from the recess. Drain passage means are provided on the piston to allow oil to flow out of the groove at a lesser rate than it is supplied by the supply passage from the recess.

Abstract: In a vacuum pumping device regeneration method, the temperature of the trap is raised to a temperature at which a molecule trapping chamber such as a cold molecules trapped by the trap are sublimated while the trap is maintained vacuum. Thereafter, the gas in which the molecules in a vapor state are present is removed from the trap without the temperature of the trap being raised to room temperatures without the pressure of the trap being to an atmospheric pressure. Consequently, contamination of the system can be avoided.

Abstract: A two-stage cryopump having a refrigerator including a first stage and a second stage being colder than the first stage; a condensation member having a condensation surface; a first coupler for connecting the condensation member to the second stage in a thermally conducting manner; an adsorption member having an adsorption surface and being spaced from the condensation member; and a second coupler for connecting the adsorption member to the second stage in a heat conducting manner. There is further provided a heater for heating the adsorption member during time periods for regenerating the adsorption member. The second coupler is so designed that it thermally sufficiently insulates the adsorption member from the second stage and from the condensation member at least during heating periods of the adsorption member, for preventing heating the condensation member by the heater.

Abstract: A cryopump for effecting a cooling operation by a freezing medium such as liquid helium. A plurality of radiation-heat shield plates for protecting cryopanels against an external heat radiation are provided in opposed relation to a gas inlet of the cryopump. Particularly, a plurality of groups of such radiation-heat shield plates are provided in such a manner that the radiation-heat shield plates of each group are arranged in a multi-stage manner in registry with one another in the direction of the depth of the cryopump and are disposed in parallel relation to one another. Each of the cryopanels is disposed adjacent to a rear surface of respective radiation-heat shield plates facing away from the gas inlet. With this construction, the gas molecules reflected by those radiation-heat shield plates and by a rear wall of the cryopump, are less liable to reach the gas inlet, and tend to be condensed at an increased rate on those cryopanels.

Abstract: An evacuation apparatus and method using a turbomolecular pump having a rotor provided with a plurality of rotor blades and a spacer provided with a plurality of stator blades so that gas molecules are sucked in from a suction port, compressed and discharged from an exhaust port of the turbomolecular pump is disclosed. A heat exchanger is provided at the suction port side of the turbomolecular pump to freeze-trap gas molecules from being cooled by a helium refrigerator.The gate valve is disposed upstream of the heat exchanger and is provided in a suction pipe which extends between the vacuum vessel and the turbomolecular pump. In exhausting the vacuum vessel, the gate valve is opened and, in this state, the turbomolecular pump and the helium refrigerator are run.

Abstract: To improve a cryogas pump, in particular a cryogas pump for cryogenic hydrogen fit for use in vehicles, comprising a cylinder housing and a piston which forms with the cylinder housing a first compression space for the cryogenic gas and which is mounted with a first piston section adjacent to the first compression space by a gas film in the cylinder housing such that owing to its dimensions it can be constructed so as to be fit for use in vehicles, with the shorter piston length requiring less cooling of the piston by the gas film, it is proposed that the cryogas pump comprise a second compression space with which the gas film is in communication and by means of which a flow of gas can be generated in the gas film in the direction of the first compression space.

Abstract: In the pumping element of a cryogenic sorption pump, a sorbent material is accommodated in annular spaces between heat conductor shells and porous screen shells, with the shells being attached to the cover of a cryogenic agent vessel so as to make good thermal contact therewith.

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 cryopump having at least two temperature stages for pumping gases at their optimal temperatures. A first embodiment has a third temperature stage that 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 stages 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. Another embodiment has at least a second stage, a temperature sensor, and a heater to maintain the second stage temperature at optimal level for the gas being pumped.

Abstract: A cryogenic pump of the type operated with a two-stage refrigerator. A first refrigerator stage includes a plurality of first-stage pump surfaces, and a second refrigerator stage includes a plurality of second stage pump surfaces. The second-stage pump surfaces include a plurality of plates arranged parallel to one another to form a generally cuboid configuration. Each of the plates has a generally rectangular planar surface bounded by a pair of bevels extending angularly from opposite longitudinal edges of the planar surface. The plates are spaced a predetermined distance away from one another, and the bevels have a predetermined width that is equal to or greater than the distance between the plates. The plates are at least partially covered with an adsorption material. In a further embodiment, the plates may include first and second bevel sections.

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: Method and apparatus for checking the operation of a refrigerator-operator cryogenic pump. The method for checking the operation of a refrigerator-operated cryogenic pump having a cold head with at least one refrigerating unit that is equipped with a pump surface. Various data of the cryogenic pump, particularly the net refrigerating power of the refrigerating unit, are interrogated under various operating conditions and these data are compared to rated data. The method and apparatus are also directed to a diagnostic apparatus with which the interrogation is implemented.

Abstract: The invention relates to a method of adapting a twostage refrigerator cryopump to a specific gas; the cryopump includes a first cooling stage to which pump surfaces are fastened and which is equipped with a heating device; the cryopump further includes a second cooling stage to which pump surfaces are fastened and which, during operation, takes on a temperature of up to 20 K. In order to enable the pump to perform at an optimum level for gases having different vapor pressures, it is proposed to control the heating device in such a manner that the coldest location of the first cooling head or, more precisely, of its pump surfaces, has a temperature which is higher by 5 to 10 K than the vapor pressure temperature of the respective gas associated with the maximum process pressure.

Abstract: An immersion pump, especially for low-boiling fluids, having a support for a shaft and a ferromagnetic impeller wheel mounted to the shaft. The support includes at least one controllable electromagnet that operates to axially support and position the impeller wheel. An outlet path is also provided to enable vapor bubbles within the moving fluid to escape from the pump and be returned to the liquid supply.

Abstract: A turbomolecular pump having a rotor provided with a plurality of rotor blades and a spacer provided with a plurality of stator blades so that gas molecules are sucked in from a suction port, compressed and discharged from an exhaust port. The pump further has a heat exchanger provided inside the suction port, the heat exchanger being connected to a refrigerator through a refrigerant pipe and a gate valve provided on the upstream side of the suction port. Gases having low molecular weights, particularly water vapor, are freeze-trapped on the heat exchanger. Thus, it is possible to efficiently exhaust gases having low molecular weights, particularly water vapor, and hence to obtain a high vacuum of good quality. In addition, it is easy to start and suspend operation of the system and possible to run it on a continuous basis.

Abstract: A cryogenic vacuum pump includes, in an integral assembly, temperature sensors and heaters associated with the first and second stages of the cryopumping array, a roughing valve and a purge valve. An electronic module removably coupled in the assembly responds to all sensors and controls all operations of the cryopump including regeneration thereof. System parameters are stored in a nonvolatile memory in the module. Included in the regeneration procedures are an auto-zero of the pressure gauge, heating of the array throughout rough pumping, and a change in pressure rate test to determine stall in rough pumping. The electronic module also restarts the system after power failure, limits use of a pressure gauge to safe conditions, provides warnings before allowing opening of the valves while the cryopump is operating and stores sensor calibration information. Control through a control pad on the pump may be limited by a password requirement. Password override is also provided.

Abstract: In a method for conveying a liquid at or in the proximity of its boiling temperature, in particular, liquid hydrogen, by means of a pump which draws the liquid from a storage container through a suction entrance port, in order to prevent undesired bubble formation in the suction region, it is proposed that the pressure in the storage container be increased for a short time during the suction phase of the pump above the equilibrium pressure of the liquid in the storage container. An apparatus for performing this method is also described.

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.