Cryopump System Research Articles

1426. A cryopumping system for balloon-borne mass spectrometers: R O Woods and T K Devlin, Rev Sci Instrum, 45 (1), 1974, 136–137

1426. A cryopumping system for balloon-borne mass spectrometers: R O Woods and T K Devlin, Rev Sci Instrum, 45 (1), 1974, 136–137

Evaluation of a liquid-helium cryopumping system operating with an electron beam gun

A recently developed 14-kW 240 ° electron beam gun was installed in an 18-in. glass belljar pumped by a liquid-helium cryopumping system made by Air Liquide, a French supplier of cryogenic pumps. The cryogenic pump has a speed of 6000 liter/sec for air. Pumping of hydrogen and helium is accomplished by bleeding in a small amount of argon which freezes on the helium reservoir and has a gettering effect on these gases. Experiments were conducted to determine the operating characteristics of this type of system when evaporating various materials such as aluminum, copper, and tantalum. Data taken during the evaporation runs consisted of major gases evolved, time for belljar pressure to recover to 10−7 Torr range, pressure during evaporation, effectiveness of argon sublimator in reducing pressure, and pumpdown curves. It was found that using a liquid-helium cryopumping system in conjunction with an electron beam gun gives exceptional results. It would be particularly advantageous in the fabrication of MOS devices where extreme cleanliness is required.

A cryopumping system for balloon-borne mass spectrometers

A change in geometry from that of the usual laboratory zeolite pump provided more efficient thermal insulation. Zeolite was packaged in a manner which gave a large surface-to-volume ratio and effective heat transfer during bakeout and cooling.

A cryopumped ion-bombardment ion source for the trace analysis of solids

A cryopump system was developed for an ion-bombardment ion source used in mass spectrometric trace analysis of solids. The purpose of the system was to decrease the partial pressure of oxygen, nitrogen and hydrogen below 10 −8 torr within the ion source. A cryopump with an evaporator cryostat and a pumping efficiency of 10,000 1-sec −1 is operated with liquid helium as the freezing agent. A report on the operation and performance of the pump system as well as its influence upon the secondary ion yields is given.

The Cryopumping System for the Indiana University 200 WeV Cyclotron

The cryopumping system for the 200 MeV cyclotron being designed and built at Indiana University is described. The volume of the vacuum chamber is approximately 28,000 liters and the estimated net area is 3.5 × 106 cm2. Two flange mounted cryopump assemblies are used to reach a pressure in the low 10-6 Torr region. Each assembly consistg of a 20°K refrigerator which uses ambient temperature helium gas and a chevron radiation shield which uses helium gas in a closed cycle at a nominal 80°K from a cryogenerator. The pumping speed of each pump is in the region of 30,000 1/s for nitrogen at 1 × 10-5 Torr or less, plus 250,000 1/s for water vapor. Liquid nitrogen is not used for cooling the radiation shield because of explosive hazards. A cryogenic heat exchanger (part of the closed cycle) in a safe location can be used also with liquid nitrogen for cooling the 80°K helium circuit should the cryogenerator be out of use for more than its scheduled maintenance period. A method for cryopumping a beam line is also described.

A cryopumping system with two cryogenic condensers for molecular beam experiments

A cryopumping system with two cryogenic condensers for molecular beam experiments

1166. Complex study of the secondary-emission properties of vacuum-melted copper

Forschungszentrum Karlsruhe (FZK) is developing the cryopumps for the ITER Neutral Beam Injectors (NBI). The system is characterized by high gas flows against which the cryopumping system must maintain the required pressures down to 10−3 Pa in the beam line vessel. During detailed investigations of the gas dynamics in the neutral beam system it showed up that in the close geometry of the beam line design a cryopump with a gas capture probability of 30% is needed to cover the low pressures. This cannot be achieved by a classical cryopump design using a chevron baffle because it is limited to gas capture probabilities below 24%.Therefore, a novel cryopump has been developed which is characterised by a gas capture probability of 33%. The engineering design of the pump takes into account that it will be operated under the conditions of the ITER cryosupply. Under these conditions the heat load to the low temperature circuits of the new cryopump design is only 20% higher than for the classical cryopump which is in regard of the 50% higher pumping speed a very good improvement of the entire efficiency. The new cryopump design is now the reference design for the ITER Heating NBI. Two cryopumps will be integrated in the beam line vessel, each of them about 8 m long and 2.75 m high resulting in an overall pumping speed for hydrogen (H2) of 5000 m3 s−1.This paper describes the vacuum conditions of the ITER Heating NBI and summarizes the pumping properties of the cryosorption pump as well as to the investigations on the heat loads to the cryogenic circuits.

1159. The design, construction and performance of a caesium-beam tube

Forschungszentrum Karlsruhe (FZK) is developing the cryopumps for the ITER Neutral Beam Injectors (NBI). The system is characterized by high gas flows against which the cryopumping system must maintain the required pressures down to 10−3 Pa in the beam line vessel. During detailed investigations of the gas dynamics in the neutral beam system it showed up that in the close geometry of the beam line design a cryopump with a gas capture probability of 30% is needed to cover the low pressures. This cannot be achieved by a classical cryopump design using a chevron baffle because it is limited to gas capture probabilities below 24%.Therefore, a novel cryopump has been developed which is characterised by a gas capture probability of 33%. The engineering design of the pump takes into account that it will be operated under the conditions of the ITER cryosupply. Under these conditions the heat load to the low temperature circuits of the new cryopump design is only 20% higher than for the classical cryopump which is in regard of the 50% higher pumping speed a very good improvement of the entire efficiency. The new cryopump design is now the reference design for the ITER Heating NBI. Two cryopumps will be integrated in the beam line vessel, each of them about 8 m long and 2.75 m high resulting in an overall pumping speed for hydrogen (H2) of 5000 m3 s−1.This paper describes the vacuum conditions of the ITER Heating NBI and summarizes the pumping properties of the cryosorption pump as well as to the investigations on the heat loads to the cryogenic circuits.

667. A getter ion pump: A S Nazarov, USSR Patent 184,389, Appril 14 thApril 1965, Publ 10 thSept 1966

Forschungszentrum Karlsruhe (FZK) is developing the cryopumps for the ITER Neutral Beam Injectors (NBI). The system is characterized by high gas flows against which the cryopumping system must maintain the required pressures down to 10−3 Pa in the beam line vessel. During detailed investigations of the gas dynamics in the neutral beam system it showed up that in the close geometry of the beam line design a cryopump with a gas capture probability of 30% is needed to cover the low pressures. This cannot be achieved by a classical cryopump design using a chevron baffle because it is limited to gas capture probabilities below 24%.Therefore, a novel cryopump has been developed which is characterised by a gas capture probability of 33%. The engineering design of the pump takes into account that it will be operated under the conditions of the ITER cryosupply. Under these conditions the heat load to the low temperature circuits of the new cryopump design is only 20% higher than for the classical cryopump which is in regard of the 50% higher pumping speed a very good improvement of the entire efficiency. The new cryopump design is now the reference design for the ITER Heating NBI. Two cryopumps will be integrated in the beam line vessel, each of them about 8 m long and 2.75 m high resulting in an overall pumping speed for hydrogen (H2) of 5000 m3 s−1.This paper describes the vacuum conditions of the ITER Heating NBI and summarizes the pumping properties of the cryosorption pump as well as to the investigations on the heat loads to the cryogenic circuits.

Development of an integrated cryopump for the application in vacuum research-and production units.: Prof Dr F X Eder, Direktor bei der Kommission für Tieftemperaturforschung der Bayerischen Akademie der Wissenschaften, München, Marstallplatz 8 Dr J Hengevoss und Dipl-Ing H Wössner, Balzers Aktiengesellschaft für Hochvakuumtechnik und Dünne Schichten, Balzers, Fürstentum Liechtenstein

Progress has been made in defining the capabilities of charcoal as the most promising absorbent to be used in cryopumps for fusion power application. The capabilities of alternative methods of cryopumping helium have been examined in a literature survey and by test, and the results are described here. Considerations include pumping speed, capacity to accumulate pumped gas, ease of reconditioning, use of alternative materials and tolerance to the fusion environment. Vacuum pumps for future fusion devices must handle large quantities of helium/hydrogen isotopes and other impurities. Cryopumps or turbomolecular pumps have demonstrated the capability on a small scale, and each has an important advantage: TMPs do not accumulate gases; cryopumps can separate helium from other effluents.This paper includes a review of a method for selecting charcoals for helium cryopumping, testing of a continuously operating cryopump system, and definition of a design that is based on the requirements of the Next European Torus. Tritium limits are satisfied. The pump design incorporates the charcoal sorbent system that has been recently developed and is based on a reasonable extrapolation of current state-of-the-art. Evaluation of alternative methods of separating helium and other gases led to selection of a movable barrier as the preferred solution.

Coating cryopump surfaces with molecular sieve materials: A Sands and S M Dick,Vacuum, 16 (12), Dec 1966, 691–694

Neutral Beam Injector (NBI) with negative ion source is under development as one of the most promising heating devices for achieving the objective plasma parameters in the Large Helical Device (LHD) at NIFS. This paper considers the development of high speed cryopumps for the NBI in the LHD. A new type of louvre blind cryopump having parallel 80 K louvre blinds and 3.7K cryopanels, located parallel to the 80 K louvre blinds, is proposed.At the ratios of B/C = 0.92 and D/B = 1.2, the transmission probability of this advanced type is calculated to be 0.72 which means the cryopump system with this louvre blind type can theoretically attain a high pumping speed.

743. Corrosion in mercury diffusion pumps: E W Gooden, “Corrosion in transport and industry”, 6th Ann Conf Australasian Corrosion Assoc, 15–19 Nov 1965, 6 pages

Forschungszentrum Karlsruhe (FZK) is developing the cryopumps for the ITER Neutral Beam Injectors (NBI). The system is characterized by high gas flows against which the cryopumping system must maintain the required pressures down to 10−3 Pa in the beam line vessel. During detailed investigations of the gas dynamics in the neutral beam system it showed up that in the close geometry of the beam line design a cryopump with a gas capture probability of 30% is needed to cover the low pressures. This cannot be achieved by a classical cryopump design using a chevron baffle because it is limited to gas capture probabilities below 24%.Therefore, a novel cryopump has been developed which is characterised by a gas capture probability of 33%. The engineering design of the pump takes into account that it will be operated under the conditions of the ITER cryosupply. Under these conditions the heat load to the low temperature circuits of the new cryopump design is only 20% higher than for the classical cryopump which is in regard of the 50% higher pumping speed a very good improvement of the entire efficiency. The new cryopump design is now the reference design for the ITER Heating NBI. Two cryopumps will be integrated in the beam line vessel, each of them about 8 m long and 2.75 m high resulting in an overall pumping speed for hydrogen (H2) of 5000 m3 s−1.This paper describes the vacuum conditions of the ITER Heating NBI and summarizes the pumping properties of the cryosorption pump as well as to the investigations on the heat loads to the cryogenic circuits.

713. Exo-electron emission from abraded metal surfaces at high and ultrahigh vacuum: J A Ramsey, J Appl Phys, 37(1), Jan 1966, 452

Forschungszentrum Karlsruhe (FZK) is developing the cryopumps for the ITER Neutral Beam Injectors (NBI). The system is characterized by high gas flows against which the cryopumping system must maintain the required pressures down to 10−3 Pa in the beam line vessel. During detailed investigations of the gas dynamics in the neutral beam system it showed up that in the close geometry of the beam line design a cryopump with a gas capture probability of 30% is needed to cover the low pressures. This cannot be achieved by a classical cryopump design using a chevron baffle because it is limited to gas capture probabilities below 24%.Therefore, a novel cryopump has been developed which is characterised by a gas capture probability of 33%. The engineering design of the pump takes into account that it will be operated under the conditions of the ITER cryosupply. Under these conditions the heat load to the low temperature circuits of the new cryopump design is only 20% higher than for the classical cryopump which is in regard of the 50% higher pumping speed a very good improvement of the entire efficiency. The new cryopump design is now the reference design for the ITER Heating NBI. Two cryopumps will be integrated in the beam line vessel, each of them about 8 m long and 2.75 m high resulting in an overall pumping speed for hydrogen (H2) of 5000 m3 s−1.This paper describes the vacuum conditions of the ITER Heating NBI and summarizes the pumping properties of the cryosorption pump as well as to the investigations on the heat loads to the cryogenic circuits.

744. Experiments with a liquid helium cryopumped extreme high vacuum: R W Moore, Jr, Sixth Annual Symposium on Space Environmental Simulation, St Louis, Missouri, May 1965, 17 pages

Forschungszentrum Karlsruhe (FZK) is developing the cryopumps for the ITER Neutral Beam Injectors (NBI). The system is characterized by high gas flows against which the cryopumping system must maintain the required pressures down to 10−3 Pa in the beam line vessel. During detailed investigations of the gas dynamics in the neutral beam system it showed up that in the close geometry of the beam line design a cryopump with a gas capture probability of 30% is needed to cover the low pressures. This cannot be achieved by a classical cryopump design using a chevron baffle because it is limited to gas capture probabilities below 24%.Therefore, a novel cryopump has been developed which is characterised by a gas capture probability of 33%. The engineering design of the pump takes into account that it will be operated under the conditions of the ITER cryosupply. Under these conditions the heat load to the low temperature circuits of the new cryopump design is only 20% higher than for the classical cryopump which is in regard of the 50% higher pumping speed a very good improvement of the entire efficiency. The new cryopump design is now the reference design for the ITER Heating NBI. Two cryopumps will be integrated in the beam line vessel, each of them about 8 m long and 2.75 m high resulting in an overall pumping speed for hydrogen (H2) of 5000 m3 s−1.This paper describes the vacuum conditions of the ITER Heating NBI and summarizes the pumping properties of the cryosorption pump as well as to the investigations on the heat loads to the cryogenic circuits.

Cryopump system for laboratory evaporator: K J Bolton,J Scient Instrum, 42,Dec 1965, 894–895.

Cryopump system for laboratory evaporator: K J Bolton,J Scient Instrum, 42,Dec 1965, 894–895.

373. The effective evacuation rate of an electrical discharge pump: G A Vasil'ev, Pribory i Tekh Eksper, 1 1965, 147–149, (in Russian)

Progress has been made in defining the capabilities of charcoal as the most promising absorbent to be used in cryopumps for fusion power application. The capabilities of alternative methods of cryopumping helium have been examined in a literature survey and by test, and the results are described here. Considerations include pumping speed, capacity to accumulate pumped gas, ease of reconditioning, use of alternative materials and tolerance to the fusion environment. Vacuum pumps for future fusion devices must handle large quantities of helium/hydrogen isotopes and other impurities. Cryopumps or turbomolecular pumps have demonstrated the capability on a small scale, and each has an important advantage: TMPs do not accumulate gases; cryopumps can separate helium from other effluents.This paper includes a review of a method for selecting charcoals for helium cryopumping, testing of a continuously operating cryopump system, and definition of a design that is based on the requirements of the Next European Torus. Tritium limits are satisfied. The pump design incorporates the charcoal sorbent system that has been recently developed and is based on a reasonable extrapolation of current state-of-the-art. Evaluation of alternative methods of separating helium and other gases led to selection of a movable barrier as the preferred solution.

Quasi-one-fluid theory of wave propagation in a fully ionized plasma : J.E. Willett, J. Appl. Phys., 34 (3), March 1963, 574

Neutral Beam Injector (NBI) with negative ion source is under development as one of the most promising heating devices for achieving the objective plasma parameters in the Large Helical Device (LHD) at NIFS. This paper considers the development of high speed cryopumps for the NBI in the LHD. A new type of louvre blind cryopump having parallel 80 K louvre blinds and 3.7K cryopanels, located parallel to the 80 K louvre blinds, is proposed.At the ratios of B/C = 0.92 and D/B = 1.2, the transmission probability of this advanced type is calculated to be 0.72 which means the cryopump system with this louvre blind type can theoretically attain a high pumping speed.

Cryopumping simulates hyperaltitude : R.L. Chuan and D.A. Wallace, Research & Devel., 14 (3), March 1963, 48–51

Progress has been made in defining the capabilities of charcoal as the most promising absorbent to be used in cryopumps for fusion power application. The capabilities of alternative methods of cryopumping helium have been examined in a literature survey and by test, and the results are described here. Considerations include pumping speed, capacity to accumulate pumped gas, ease of reconditioning, use of alternative materials and tolerance to the fusion environment. Vacuum pumps for future fusion devices must handle large quantities of helium/hydrogen isotopes and other impurities. Cryopumps or turbomolecular pumps have demonstrated the capability on a small scale, and each has an important advantage: TMPs do not accumulate gases; cryopumps can separate helium from other effluents.This paper includes a review of a method for selecting charcoals for helium cryopumping, testing of a continuously operating cryopump system, and definition of a design that is based on the requirements of the Next European Torus. Tritium limits are satisfied. The pump design incorporates the charcoal sorbent system that has been recently developed and is based on a reasonable extrapolation of current state-of-the-art. Evaluation of alternative methods of separating helium and other gases led to selection of a movable barrier as the preferred solution.

Vacuum gauge calibration

Progress has been made in defining the capabilities of charcoal as the most promising absorbent to be used in cryopumps for fusion power application. The capabilities of alternative methods of cryopumping helium have been examined in a literature survey and by test, and the results are described here. Considerations include pumping speed, capacity to accumulate pumped gas, ease of reconditioning, use of alternative materials and tolerance to the fusion environment. Vacuum pumps for future fusion devices must handle large quantities of helium/hydrogen isotopes and other impurities. Cryopumps or turbomolecular pumps have demonstrated the capability on a small scale, and each has an important advantage: TMPs do not accumulate gases; cryopumps can separate helium from other effluents.This paper includes a review of a method for selecting charcoals for helium cryopumping, testing of a continuously operating cryopump system, and definition of a design that is based on the requirements of the Next European Torus. Tritium limits are satisfied. The pump design incorporates the charcoal sorbent system that has been recently developed and is based on a reasonable extrapolation of current state-of-the-art. Evaluation of alternative methods of separating helium and other gases led to selection of a movable barrier as the preferred solution.