Abstract: A cryopump system includes: a plurality of cryopumps connected to a common roughing pump and provided with a plurality of rough valves, respectively; and a controller configured to control each of the rough valves for regenerating a corresponding one of the plurality of cryopumps. A delay time is set between closing of an open one of the plurality of rough valves and opening of a closed one of the plurality of rough valves.

Abstract: A cryopump includes: a cryopump chamber having an inlet port through which a gas to be pumped is introduced; a refrigerator provided with a second cooling stage provided in the cryopump chamber; an intermediate member thermally coupled to the second cooling stage; and a cryopanel having a connecting part connected to the intermediate member at a position farther from the inlet port in the direction in which the gas is introduced than the second cooling stage, and extending from the connecting part toward the inlet port. For example, a cryopump having a suspended panel structure is provided.

Abstract: The invention relates to a device (21) for avoiding the memory effect in cryogenic pumps having a first cooling stage (23) and a second cooling stage (25) which adjoins the first cooling stage (23) in the axial direction. A cylindrical shield (31) has an opening (37) and a base (35), which base (35) is penetrated centrally by the two-stage cooling head (21) in such a way that the first cooling stage (23) is arranged outside the shield (31) and the second cooling stage (25) is arranged within the shield (31). An intermediate chamber (34) is formed between the shield (31) and the first cooling stage (23), and the base of the shield (31) is connected in a thermally conductive manner to the first cooling stage (23) by means of a thermal bridge (33). A cooling panel (43) which serves as pumping surface is connected to the second cooling stage (25) and is provided within the shield (31).

Abstract: A helium management control system for controlling the helium refrigerant supply from a common manifold supplies cryogenic refrigerators with an appropriate helium supply. The system employs sensors to monitor and regulate the overall refrigerant supply. An appropriate supply of helium is distributed to each cryopump. If the total refrigeration supply exceeds the demand, or consumption, excess refrigerant is directed to cryogenic refrigerators which can utilize the excess helium to complete a current cooling function more quickly. If the total refrigeration demand exceeds the total refrigeration supply, the refrigerant supply to some or all of the cryogenic refrigerators will be reduced accordingly so that detrimental or slowing effects are minimized based upon the current cooling function.

Abstract: A thermoacoustic device 1 for improving heat exchange efficiency is provided which has a first stack 3a including stack constituent elements 3eL and 3eH laminated together, and a first high-temperature side heat exchanger 4 and a first low-temperature side heat exchanger 5, which are provided at two ends of the first stack 3a, in which a self-excited acoustic wave is generated by a temperature difference between the first high-temperature side heat exchanger 4 and the first low-temperature side heat exchanger 5 and is then converted to thermal energy in a stack 3b provided between a second high-temperature side heat exchanger 6 and a second low-temperature side heat exchanger 7.

Abstract: A cryogen pump, including: a pump section that includes: a bellow with an inlet opening at a first end and an exit opening, the inlet opening in direct fluid communication with a volume of a cryogen, the exit opening at least in fluid communication with a second end of the bellow opposing the first end, a pair of plugs configured to sealingly close the opposing ends of the bellow, the pair of plugs cooperating so that when one plug sealingly closes one of the ends, the other end of the bellow is open; and a drive section configured to drive the pump section in a reciprocating manner so as to move the plugs.

Abstract: A cryosorber panel having nanomaterials used for the cryosorption material, with nanomaterial either grown directly on the cryopanel or freestanding nanomaterials attached to the cryopanel mechanically without the use of adhesives. Such nanomaterial cryosorber materials can be used in place of conventional charcoals that are attached to cryosorber panels with special low outgassing, low temperature capable adhesives. Carbon nanotubes and other nanomaterials could serve the same purpose as conventional charcoal cryosorbers, providing a large surface area for cryosorption without the need for adhesive since the nanomaterials can be grown directly on a metallic substrate or mechanically attached. The nanomaterials would be capable of being fully baked by heating above 100° C.

Abstract: A cryopump includes a cryopump including: a refrigerator; a first cryopanel including a radiation shield; and a second cryopanel enclosed by the first cryopanel and cooled to a lower temperature than that of the first cryopanel. The radiation shield includes an attaching pedestal located lateral to the second cryopanel for attachment of the refrigerator to the radiation shield, and a shield portion adjacent to the attaching pedestal and enclosing the second cryopanel. A lateral gap is formed between the second cryopanel and the attaching pedestal. A gap part continuing into the lateral gap is formed between the second cryopanel and the shield portion. The second cryopanel is shaped and/or located such that the lateral gap is comparable in width to the gap part.

Abstract: A cryopump includes an adsorption cryopanel including a front surface configured to receive incidence of a non-condensable gas and a back surface having an adsorption region of the non-condensable gas, and a reflection cryopanel including a reflection surface of the non-condensable gas facing the back surface. The adsorption cryopanel may have a multitude of through holes penetrating from the front surface to the back surface. The adsorption cryopanel has a passage probability of the non-condensable gas selected from a range of 10% to 70%.

Abstract: A cryopump control apparatus controls an evacuation process of a cryopump that includes a cryopanel which cools and thus condenses or adsorbs gas, and a pump housing which contains the cryopanel. The cryopump control apparatus includes a pressure control unit and a vacuum retention evaluation unit. The pressure control unit stops pumping when detecting that a pressure in the pump housing decreases to a reference pressure. The vacuum retention evaluation unit determines whether a difference between pressure values in the pump housing measured at first measurement time and at second measurement time is within an allowable range of pressure change. The first measurement time is determined by adding correction time relating to an operating delay of pumping to a time point when the pressure in the pump housing is detected to be decreased to the reference pressure.

Abstract: Systems and methods for improving the performance of dilution refrigeration systems include cryocondensation traps employed in the helium circuit of a dilution refrigerator may be modified to improve performance. A cryocondensation trap employs a cryocondensation surface having at least one temperature that preferably matches the temperature at which at least one contaminant freezes into a solid form from a gaseous form. A single trap with at least one continuous cryocondensation surface formed in a generally helical or spiral-like fashion with each region having a different temperature may be employed to trap a specific contaminant or set of contaminants. A single trap with multiple cryocondensation surfaces where each surface has a different temperature may be alternatively employed for the same purpose. To provide a temperature gradient in the cryocondensation trap, at least one region of the cryocondensation trap may be thermally coupled to a cold surface and/or a transfer tube.

Abstract: A vacuum network control system includes a plurality of nodes configured for control over operational processes of the system. The plural nodes are configured, in a network ring or other topology, as a selectable master node for controlling the operational processes. Control can be distributed among, and passed between, each of the nodes. Each node on the network monitors adjacent network connectors to detect a fault in the network. In response to a detected fault, a disconnect is mapped to the fault, and the network topology is reconfigured for continued communication among the nodes and with external devices.

Abstract: This invention provides a cold trap using a Stirling refrigerator. A refrigerator includes a drive piston configured to drive a free piston so as to reciprocally move a working medium between a heat dissipation portion and a heat absorption portion, a vibration sensor configured to measure a vibration of a case, a dynamic vibration absorber configured to reduce the vibration of the case when the drive piston is driven, and a frequency adjustment device configured to adjust a driving frequency to reduce the vibration of the case when the drive piston is driven in a state in which the case is connected to a vacuum device.

Abstract: A sample mounting apparatus for a cryo-cooler is provided having a housing with an outer wall surface for connecting to the cryo-cooler, and an inner wall surface. An inert gas is sealed inside the housing for thermal transfer, and a delicate mount is attached to the inner wall surface of the housing for supporting the sample and substantially preventing vibrations from being transferred to the sample from the cryo-cooler.

Abstract: A cryopump includes a first cryopanel including a radiation shield and a plate member across a shield opening and a second cryopanel enclosed by the first cryopanel and cooled to a lower temperature than that of the first cryopanel. The plate member includes a plate main portion and a plate peripheral portion adapted to attach the plate main portion to the radiation shield. The plate main portion includes a gas passing region having a multitude of pores through which gases pass to be condensed on the second cryopanel and a gas shielding region formed at a different position in the plate main portion from that of the gas passing region.

Abstract: A cryopump includes: a radiation shield that includes a shield front end that defines a shield opening, a shield bottom portion, and a shield side portion that extends between the shield front end and the shield bottom portion; and a cryopanel assembly that is cooled to a lower temperature than that of the radiation shield. The cryopanel assembly includes a first panel arrangement including a plurality of first adsorption panels and a plurality of second panel arrangements each including a plurality of second adsorption panels. The first panel arrangement forms a multitude of adsorption sections arranged in a lattice-shaped pattern in cooperation with the plurality of second panel arrangements, each of the adsorption sections being exposed to the shield side portion.

Abstract: A method of regenerating a cryopump includes a first discharging process that includes alternately evacuating a cryopump housing and supplying a purge gas in a first pressure range, and a second discharging process that includes evacuating the cryopump housing to a low pressure region below the first pressure range. The second discharging process includes making a determination at least once in the low pressure range as to whether the second discharging process should be terminated, and supplying the purge gas to the cryopump housing prior to a first-time determination as to whether the second discharging process should be terminated.

Abstract: A cryopump system includes a cryopump, a compressor of a working gas for the cryopump, a control device configured to control an operation frequency of the compressor, a gas line connecting the cryopump and the compressor, and a gas quantity adjustment unit configured to switch a working gas quantity of the gas line between at least a first gas quantity and a second gas quantity. When the gas line has the first gas quantity, a controllable range of the operation frequency provides a first flow rate range of the working gas. When the gas line has the second gas quantity, the controllable range provides a second flow rate range of the working gas. The second flow rate range has a non-overlapping portion with the first flow rate range.

Abstract: A cryopump includes: a cryopanel assembly including a plurality of cryopanels each having an adsorption area on both surfaces thereof; a radiation shield forming a gas receiving space that surrounds the cryopanel assembly; and a radiation cover disposed in a cryopump inlet. The radiation cover includes a main plate located at a position in the cryopanel inlet that corresponds to the cryopanel assembly and a louver portion located at a position in the cryopanel inlet that corresponds to the gas receiving space. The radiation cover may not include the louver portion.

Abstract: A biogas purification method includes injecting biogas into a pressure vessel, cooling the pressure vessel to a first predetermined temperature and pressurizing the pressure vessel to a predetermined pressure. The method further includes visually monitoring separation of a biogas impurity from a product gas during an induction period, isolating the product gas from the biogas impurity at a clathrate formation equilibrium by removing the product gas from the pressure vessel and passing the product gas through water to yield a purified gas.

Abstract: A cryopump for evacuating a vacuum chamber is provided with a radiation shield provided with a shield opening end surrounding a shield opening for receiving a gas and a lid member having a connection opening narrower than a shield opening for connecting the shield opening to the vacuum chamber. The lid member is provided with a first mounting flange for mounting the cryopump on a mating flange provided with the vacuum chamber. The first mounting flange surrounds the connection opening on a vacuum chamber side of the lid member.

Abstract: A cryopump includes a high-temperature cryopanel, a low-temperature cryopanel, and a cooling system. The cooling system has: a refrigerator provided with a first stage for cooling the high-temperature cryopanel and a second stage for cooling the low-temperature cryopanel; and a control unit configured to control a cool-down operation in which the first stage and the second stage are cooled in order to initiate a vacuum pumping operation of the cryopump. The cooling system may be configured to selectively provide a cooling relief effect to the first stage at least temporarily in the cool-down operation.

Abstract: A cryopump comprises a cryopanel that cools and thus condenses or adsorbs gas, and a pump housing that contains the cryopanel. a regeneration process of the cryopump includes a basic purge process, an evacuation processes, and an optional purge process that is executed additionally if required. The optional purge process includes one or more gas purge steps. In a cryopump control apparatus that controls the cryopump, a deterioration evaluation unit determines whether a re-purge number, which is the total number of gas purge steps that are required to be executed in one regeneration process, reaches a deterioration evaluation criteria number.

Abstract: A cold trap is provided with a cold panel provided in a pumping path such that the panel is exposed, a refrigerator thermally coupled to the cold panel and operative to cool the cold panel; and a controller configured, in a regeneration process for evaporating a gas frozen on the surface of the cold panel and discharging the gas outside using the vacuum pump, to control the refrigerator so as to raise the temperature of the cold panel to a temperature exceeding a non-liquefaction temperature range and to adjust a pressure in the pumping path at the temperature so that the gas frozen on the surface of the cold panel is evaporated without being melted, the non-liquefaction temperature range being a range in which it is guaranteed that a gas frozen on the surface of the cold trap is evaporated without being melted.

Abstract: A method and system for controlled rate freezing of biological materials is provided. The presently disclosed system and method provides the ability to rapidly cool the biological materials contained in vials or other containers within a cooling unit via forced convective cooling using a laminar and uniform flow of cryogen in proximity to the plurality of vials disposed within the cooling unit. The rapid cooling of the biological materials is achieved by precisely controlling and adjusting the temperature of the cryogen being introduced to the system as a function of time.

Abstract: A cold trap includes a duct, which is for connecting a volume to be evacuated to a vacuum pump, and a cold panel surrounded by the duct. The duct includes an inlet flange at an evacuation target side and an outlet flange at a vacuum pump side. The outlet flange is arranged at a distance from the inlet flange in the extending direction of the duct. The inlet flange has an outer diameter larger than an outer diameter of the outlet flange.

Abstract: The rotary type ultralow temperature refrigerant supply apparatus includes a refrigerant introduction pipe coupled to the super conductive rotor for supplying a liquid-phase ultralow temperature refrigerant cooled by the refrigeration system to the evaporator, a refrigerant withdrawal pipe disposed spaced apart from the refrigerant introduction pipe for withdrawing a gas-phase ultralow temperature refrigerant obtained through the evaporation of the liquid-phase refrigerant by the evaporator and guiding the withdrawn gas-phase ultralow temperature refrigerant to the refrigeration system, and a vacuum housing fixedly disposed outside the refrigerant introduction pipe and the refrigerant withdrawal pipe, the vacuum housing having a vacuum heat insulation space defined inside.

Abstract: Systems and methods for improving the performance of dilution refrigeration systems are described. Filters and traps employed in the helium circuit of a dilution refrigerator may be modified to improve performance. Some traps may be designed to harness cryocondensation as opposed to cryoadsorption. A cryocondensation trap employs a cryocondensation surface having a high thermal conductivity and a high specific heat with a binding energy that preferably matches at least one contaminant but does not match helium. Multiple traps may be coupled in series in the helium circuit, with each trap designed to trap a specific contaminant or set of contaminants. Both cryocondensation and cryoadsorption may be exploited among multiple traps.

Abstract: A cryopump includes a nested array of cryopanels. A hydrogen molecule incident into a clearance in the nested array of cryopanels is reflected by a cryopanel. The reflected hydrogen molecule is adsorbed by another cryopanel. Each of the cryopanels may have an inverted frustum shape.

Abstract: A method is described for separating off trace components from a fraction (1) containing at least nitrogen and helium, wherein this fraction is partially condensed (E) before enrichment of the helium. The partially condensed fraction (2) is fed at least in part to at least one separation column (T) and separated therein into a helium-rich gas fraction (6) and a nitrogen-rich liquid fraction which also contains the unwanted trace components (5).

Abstract: An instrument to provide on-site analyses utilizing a combination cryotrap and absorbent traps in the extraction of constituents from the sample gas stream consistent with the requirements of 40 CFR Pt. 60 App. A Method 25. The air sample is passed through a cryotrap system which is maintained at the temperature of dry ice ˜72° C.). Heavier molecular weight constituents in the gas sample are condensed on the cold surfaces of the trap. The lighter molecular weight constituents are retained in the absorbent trap, while also acting as a column to separate methane, carbon dioxide, and carbon monoxide from each other and the remain carbon compounds. After separation, all of the sample constituents are oxidized to carbon dioxide and reduced to methane prior to being introduced to a Flame Ionization Detector, which measures the concentration of each against known calibration standards.

Abstract: An apparatus is provided for drying a gas by gradually releasing and condensing the moisture in various chambers of a column, different pressures and different temperatures thus being present in the chambers of the column. The gas to be dried is first fed into the bottom chamber, where the largest amount of the water contained in the gas is condensed, and the gas is then discharged from the bottom chamber via a nozzle. Subsequently the gas is cooled and fed into at least one more chamber located above the first chamber, where further moisture is condensed before the resulting condensate is fed via a pipe—preferably shaped like a siphon—into the bottom reservoir to prevent the gas from flowing from the chamber below into the chamber above. A process which enables a gas to be dried is also described.

Abstract: A cryopump has a simple-to-manufacture frontal baffle plate with improved gas distribution and has a large-area second-stage array plate to capture Type II gases. The cryopump has a first-stage frontal baffle plate having orifices and flaps bent from and attached to the orifices. The cryopump has a second-stage top plate that is larger in area than cooling baffles of the second stage array.

Abstract: A multi-stage pulse tube refrigerator includes a first stage regenerator tube including a heat exchanger; a second stage regenerator tube; a first stage pulse tube; a second stage pulse tube; a first cooling stage connected to the first stage regenerator tube and the first stage pulse tube; and a second cooling stage connected to the second stage regenerator tube and the second stage pulse tube. A cold end of the first stage regenerator tube is connected to the first stage pulse tube via a first flow path and connected to the second stage regenerator tube via a second flow path. The first flow path is configured such that a heat exchange occurs between the heat exchanger and a refrigerant gas flowing through the first flow path, and the second flow path is configured such that the refrigerant gas flowing through the second flow path bypasses the heat exchanger.

Abstract: A cold trap includes a refrigerator and a cold panel that is thermally connected with the refrigerator to be cooled. A rough surface is formed on the cold panel. The cold trap is arranged, for example, in an evacuation channel for connecting a vacuum chamber with a turbo-molecular pump in order to freeze and capture, on a surface thereof, part of a gas that is to be sucked and pumped into the turbo-molecular pump from the vacuum chamber through the evacuation channel.

Abstract: A means of rapidly melting a large quantity of type II cryogen in a cryopump that is configured to contain the liquid in the warm cryopanel with the inlet to the cryopump facing up or sideways, and venting the liquid and gas in a controlled way. Rapid melting is preferably accomplished by flowing a purge gas that will condense on the cryodeposit. By not allowing the liquid to drain onto the vacuum housing the evaporation rate is limited and the maximum pressure in the cryopump can be controlled by the purge gas flow rate.

Abstract: Faster cool down time is achieved in a low profile cryopump by having heat transferred directly from the inlet louver to the first stage heat station through one or more tapered thermal busses, and by obviating the need of a thermal shield over the second stage cylinder of the expander by having second stage cryopanels that form a nested tent like structure, at least one of which, extends over the cylinder.

Abstract: A cryopump system includes a cryopump having a first cooling stage and a second cooling stage connected to the first cooling stage, the second cooling stage including a gas adsorber having a hydrogen adsorbing capacity of at least about 2 standard liters. The thermal storage capacity of the second cooling stage is sufficient to enable control of hydrogen pressure within the cryopump to satisfy ignition safety limits and limits on hydrogen flow rate in an exhaust line to be within limits of an abatement system to be coupled to the cryopump, upon warming of the second cooling stage during regeneration of up to a fully loaded cryopump.

Abstract: A cryopump system includes a cryopump configured to perform a preparatory operation including a cooldown from a room temperature to a cryogenic temperature and to perform a vacuum pumping operation at the cryogenic temperature, a compressor unit of a working gas for the cryopump, a gas line connecting the cryopump and the compressor unit, a gas volume adjuster configured to increase a quantity of the working gas in the gas line during the vacuum pumping operation in comparison with that during the preparatory operation, and a control device configured to control the compressor unit so as to provide a pressure control for the gas line.

Abstract: A method for regenerating a cryopump includes stopping a pressure sensor for the cryopump, starting to heat a cryogenic surface for adsorbing gas molecules, starting the rough evacuation of the cryopump while the pressure sensor is stopped, and terminating the rough evacuation while the pressure sensor is stopped. This method may include activating the pressure sensor after the rough evacuation has been terminated.

Abstract: A cryopump includes: a first panel to be cooled by a first stage of a refrigerator; a second panel to be cooled by a second stage of the refrigerator; a panel temperature sensor provided with the first panel and/or the second panel; a stage temperature sensor provided with the first stage and/or the second stage; and a control unit that controls vacuum pumping based on the temperature measured by the stage temperature sensor. The control unit controls regeneration including a heating process of a cryopanel, and uses the temperature measured by the panel temperature sensor exclusively in the regeneration. The control unit completes the heating process based on the temperature measured by the panel temperature sensor.

Abstract: A cryogenic apparatus is provided having a nested thermally insulating structure, thermal links, a vacuum shroud, and a cryo-cooler. The nested thermally insulated structure holds a sample to be cooled while dampening the external vibrations caused by the cryo-cooler, the surrounding environment or cryo-cooler mounting surface. A vacuum plate is removably attached to the vacuum shroud to provide access to the sample chamber.

Abstract: A refrigerator system or cryopump includes a first refrigerator having at least first and second stages, and a second refrigerator. A thermal coupling between the first stage of the first refrigerator and a cold end of the second refrigerator is restricted to maintain a temperature difference between the cold end of the second refrigerator and the first stage of the first refrigerator. The refrigerator system or cryopump also includes a radiation shield in thermal contact with the cold end of the second refrigerator, and a condensing surface, spaced from and surrounded by the radiation shield, and in thermal contact with a second stage, e.g., coldest stage, of the first refrigerator. The restricted thermal coupling can be configured to balance the cooling load on the two refrigerators.

Abstract: A cryopump includes a low-temperature cryopanel, a high-temperature cryopanel provided outside the low-temperature cryopanel, and a housing provided outside the high-temperature cryopanel. The high-temperature cryopanel includes an extension panel extending outward. The housing includes an inlet flange surrounding the extension panel.

Abstract: A cold trap includes two individually controllable cooling units. The cold trap is provided in an evacuation path for connecting a vacuum chamber to a turbomolecular pump, The first cooling unit includes a first panel unit provided in the evacuation path such that the panel is exposed, and a first refrigerator thermally coupled to the first panel unit so as to cool the first panel unit. The second cooling unit includes a second panel unit provided in the evacuation path such that the panel is exposed, and a second refrigerator thermally coupled to the second panel unit so as to cool the second panel unit. The first panel unit is spaced apart from the second panel unit.

Abstract: A cryopump includes a housing, an electrical control unit which controls the cryopump, a purge valve provided on a passage between an external purge gas source and the inside of the housing, a rough valve provided on a passage between an external pump and the inside of the housing, a vent valve provided on a passage between the inside and the outside of the housing, and a Pirani gauge which measures a pressure inside the housing. The electrical control unit is connected to each of the purge valve, rough valve, vent valve, and Pirani gauge via a wire. Each of the wires is provided with a connector on the component side and a connector on the electrical control unit side. The connector on the component side is configured to be attachable to and detachable from the connector on the electrical control unit side.

Abstract: A compressor controller includes: a control amount calculation unit configured to calculate at least two control amounts including a first control amount for controlling a first control object that relates to a gas amount for cooling a cryogenic apparatus, and a second control amount for controlling a second control object that relates to the refrigerant gas amount and that is different from the first control object, the second control amount being common with the first control amount; and a selection unit configured to select a control object to be controlled from at least two control objects including the first control object and the second control object on the basis of a comparison between the at least two common control amounts.

Abstract: A cold trap filter and method is provided for filtering chemical species from a vacuum system of an ion implantation system. A canister is in fluid communication with an exhaust of a high vacuum pump and an intake of a roughing pump used for evacuating an ion source chamber. One or more paddles are positioned within the canister, wherein each paddle has a cooling line in fluid communication with a coolant source. The coolant source passes a coolant through the cooling line, thus cooling the one or more paddles to a predetermined temperature associated with a condensation or deposition point of the chemical species, therein condensing or depositing the chemical species on the paddles while not interfering with a vacuum capacity of the high vacuum and roughing pumps. The paddles can also be electrically biased to electrostatically attract the chemical species to the paddles in one or more biasing steps.

Abstract: A system and method for trapping and collecting volatile compounds is described. The system and method generally include a trapping column including adsorption materials positioned within a lumen of the trapping column, an oven for heating the trapping column, and a cold-trap condenser. When a sample containing a volatile compound is passed through the lumen of the trapping column, the volatile compound is captured on or in the adsorption material. The captured volatile compound is subsequently released from the trapping column by simultaneously heating the column in the oven while a gas is pushed through the lumen of the column, and the released volatile compound is collected in the cold-trap condenser.

Abstract: The invention relates to a device (21) for avoiding the memory effect in cryogenic pumps having a first cooling stage (23) and a second cooling stage (25) which adjoins the first cooling stage (23) in the axial direction. A cylindrical shield (31) has an opening (37) and a base (35), which base (35) is penetrated centrally by the two-stage cooling head (21) in such a way that the first cooling stage (23) is arranged outside the shield (31) and the second cooling stage (25) is arranged within the shield (31). An intermediate chamber (34) is formed between the shield (31) and the first cooling stage (23), and the base of the shield (31) is connected in a thermally conductive manner to the first cooling stage (23) by means of a thermal bridge (33). A cooling panel (43) which serves as pumping surface is connected to the second cooling stage (25) and is provided within the shield (31).