Cryopump Research Articles

Linde pioneers hydrogen compression techniques for fuel cell electric vehicles

Innovative hydrogen compression technology is needed to help roll out the required hydrogen infrastructure to refuel the growing number of fuel cell electric vehicles (FCEVs) that are expected to hit the road in the next few years. The Linde Group has been at the forefront of these advances, and many of the world's hydrogen fueling stations (HFS) are equipped with Linde technology. The company has developed a cryogenic hydrogen pump and ionic compressor, the latter being a key feature at the world's first small-series production facility unveiled in July in Vienna.

宇宙成因<sup>21</sup>Ne暴露测年方法的初步建立及检验

The stable cosmogenic isotope ²¹Ne provides an extremely powerful tool for surface exposure dating, because of its extremely wide exposure dating range, requirement for comparatively small samples (about 0.2-1.0 g), and relatively simple sample preparation process. Furthermore, in addition to quartz, ²¹Ne analysis is applicable to many other types of silicate, such as pyroxene, olivine, and biotite. Cosmogenic ²¹Ne has become a significant geochronological technique in Quaternary geology; however, because of the high resolution required to separate the ⁴⁰Ar²⁺ peak from that of ²⁰Ne⁺ in mass spectrometry, the development of the cosmogenic ²¹Ne exposure dating technique in China is still in its early stages. A measurement procedure has been established in our laboratory for cosmogenic ²¹Ne dating based on improvement of the purification system of the mass spectrometer by adding a cryogenic pump. A highly enriched ²¹Ne standard material (CREU-1) and an alluvial fan surface sample from Longshou Shan, Inner Mongolia, China, were analyzed, and the data from these two samples have demonstrated the feasibility of our ²¹Ne analytical procedure for quartz. The establishment of this neon analytical procedure provides a promising tool for the development of a cosmogenic ²¹Ne dating method for use in many fields, such as Quaternary geology and active tectonics.

초저온 피스톤 펌프의 성능 향상에 관한 연구

In order to develop a universal cryogenic piston pump of small size for increasing utilization of liquid hydrogen, dynamic compression performance of piston pump were evaluated and improvements were also discussed for piston rod and piston tip. The cryogenic piston pump has crosshead structure and inclined cup shape piston tip. As the results, it was found that i) insulation of heat flow from piston-rod part is required for stable operation ii) improving the self-clearance adjustment effect of piston tip and reducing piston eccentricity were desirable to promote pumping pressure and operating range.

Consequences of plasma disruption mitigation by massive gas injection on the ITER torus cryopumping system

The ITER torus exhaust pumping system is based on six primary vacuum cryogenic pumps, and a rough and regeneration pumping system that can pump the exhaust gases from the torus cryopumps to the tritium plant. Massive gas injection is a proposed concept to mitigate plasma disruptions in ITER. The present paper identifies the limitations and down-times of the ITER torus pumping system after a massive gas injection event. Deuterium, helium, neon, and argon injections are discussed. The resulting high pressure in the torus is leading to high mass flows and heat fluxes to the cryogenic pumps, resulting in a significant and rapid temperature increase of the pumping surfaces normally cooled at 5K. However, the consequences on the torus pumping system operation depend on the gas species and quantities injected. Finally, the regeneration of the cryopumps, the rough pumping of the torus, and the overall torus pumping system turnover time until vacuum and thermal conditions for the start of the next plasma pulse are initiated again are discussed.

Marine environment compatible antireflection coating with nanotop layer on silicon optics

Antireflection coating on silicon optics have crucial importance in thermal device working in 3.6–4.9μm wavelength region. When the thermal device is used in marine environment, the optics face harsh saline weather condition compared to normal field environment. This deteriorates coated optics and to improve mechanical strength of the coating, a nanotop layer on the antireflection coating has been developed. In this paper a study has been carried out to improve marine environment compatibility by employing a nanolayer on the top of antireflection coating on silicon optics. Optimac synthesis method was used to design the multilayer stack on the substrate with germanium and IR-F625 as high/low refractive index respectively and the layer number was restricted to four layers. The top nanolayer was 60±2nm thick hafnium dioxide layer developed with ion assisted deposition (End–Hall) on the optics during coating process. The deposition of multilayer coating was carried out inside the coating plant fitted with cryo pump and residual gas analyzer. The evaporation was carried out at high vacuum (2–6×10−6mbar) using electron beam gun and layer thicknesses were measured with crystal monitor. The average transmission achieved was 97% in the spectral band of 3.6–4.9μm with a hardness of 9.7GPa on the coated optics.

The dynomak: An advanced spheromak reactor concept with imposed-dynamo current drive and next-generation nuclear power technologies

A high-β spheromak reactor concept has been formulated with an estimated overnight capital cost that is competitive with conventional power sources. This reactor concept utilizes recently discovered imposed-dynamo current drive (IDCD) and a molten salt (FLiBe) blanket system for first wall cooling, neutron moderation and tritium breeding. Currently available materials and ITER-developed cryogenic pumping systems were implemented in this concept from the basis of technological feasibility. A tritium breeding ratio (TBR) of greater than 1.1 has been calculated using a Monte Carlo N-Particle (MCNP5) neutron transport simulation. High temperature superconducting tapes (YBCO) were used for the equilibrium coil set, substantially reducing the recirculating power fraction when compared to previous spheromak reactor studies. Using zirconium hydride for neutron shielding, a limiting equilibrium coil lifetime of at least thirty full-power years has been achieved. The primary FLiBe loop was coupled to a supercritical carbon dioxide Brayton cycle due to attractive economics and high thermal efficiencies. With these advancements, an electrical output of 1000MW from a thermal output of 2486MW was achieved, yielding an overall plant efficiency of approximately 40%.

Development of Advanced Exhaust Pumping Technology for a DT Fusion Power Plant

The main functions of the exhaust pumping system of a Deuterium-Tritium (DT) fusion device are to pump out the helium ash and control the divertor neutral gas density. This requires the handling of large gas throughputs at high pumping speeds (but at relatively moderate vacua). The pumped exhaust gas is then usually transported to the tritium plant for cleaning, which involves impurity removal and separation of the pure hydrogenic species for reinjection as fuel. In view of a fusion power plant, a systematic technical review of primary and roughing pump technologies is conducted in order to identify potential exhaust pumping concepts, which eliminate some of the disadvantages that eventually result from simple scale-up of the ITER solutions that are based on batchwise operating cryogenic pumps. This paper also illustrates the methodology applied to come to unbiased results and describes the final configuration, which is based on a vapor diffusion pump as primary pump together with a metal foil pump for hydrogen separation, and a liquid metal ring pump as roughing pump. All pumps are working continuously and do not require cryogenic temperatures. The new concept will reduce the tritium inventories of a power plant: 1) because of the continuous pumping characteristics of the pumps involved and 2) because the metal foil pump allows for internal recycling of the unburnt fuel species directly from the divertor to the fuelling systems, bypassing the tritium plant. A research and development program was initiated in EU to demonstrate the feasibility of this novel approach and, thus, to make it the reference solution for a fusion power plant. The current status in this effort is summarized, and the test facility to be employed is described in full detail.

Simulation of a Condition Monitoring Scheme for a Neutral Beam Injector Cryogenic Pump

This paper presents the simulation testing of a model-based condition monitoring scheme for the Joint European Torus neutral beam cryogenic pumping system. The scheme was tested by examining its response to a range of realistic simulated faults. Ten faults were tested. The scheme detected each of the faults and uniquely identified six of them. The scheme was shown to have an improved performance compared to the current manual detection method.

828 能動4軸制御磁気軸受を用いた極低温ポンプの研究

828 能動4軸制御磁気軸受を用いた極低温ポンプの研究

DSMC simulation of rarefied gas mixtures flows driven by arrays of absorbing plates

Gas flows induced by arrays of absorbing surfaces of various shapes are met in several vacuum technology devices, like NEG or cryogenic pumps. In order to obtain a simplified model of low pressure gas dynamics driven by surface absorption, flows of rarefied gas binary mixtures past arrays of absorbing plates are studied by numerical solution of a system of coupled and spatially two-dimensional Boltzmann equations. The overall absorption rate is obtained as a function of problem parameters which include the characteristic flow Knudsen number and wall absorption probabilities. Particular attention is devoted to mixtures flows in which one of the components is present in small amounts and it is weakly absorbed.

The Direct Internal Recycling concept to simplify the fuel cycle of a fusion power plant

A new concept, the Direct Internal Recycling (DIR) concept, is proposed, which minimizes fuel cycle inventory by adding an additional short-cut between the pumped torus exhaust gas and the fuelling systems. The paper highlights quantitative modelling results derived from a simple fuel cycle spreadsheet which underline the potential benefits that can be achieved by implementation of the DIR concept into a fusion power plant.DIR requires a novel set-up of the torus exhaust pumping system, which replaces the batch-wise and cyclic operated cryogenic pumps by a continuous pumping solution and which offers at the same time an additional integral gas separation function. By that, hydrogen can be removed close to the divertor from all other gases and the main load to the fuel clean-up systems is a smaller, helium-rich gas stream. Candidate DIR relevant pump technology based on liquid metals (vapour diffusion and liquid ring pumps) and metal foils is discussed.

New options for material testing at the material ion beam test facility MARION

Within the development of new fusion devices like ITER and DEMO, material testing becomes more and more relevant. The material ion beam test facility MARION which was primarily designed for beam source development and commissioning is also used for high heat flux testing up to 120MW/m2 power density. In order to improve this second field of activity the concept of MARION is adapted to material testing. To increase the flexibility and to decrease the costs for material testing operation the vacuum system has been changed by excluding the cryogenic pumps combined with an enhancement of the conventional vacuum pumping part. The reduction in pumping capacity has made a new optimization of the operation parameters necessary.The experimental results of this optimization can be used as calibration base for future heat load tests. They are shown in this paper, combined with the changes in operation range for this new, additional mode.

Heat transfer enhancement of NBI vacuum pump cryopanels

Huge cryogenic pumps are installed inside neutral beam injectors in order to manage the typically very large gas flows. This paper deals with the aspect of passive cooling in NBI cryopump design development and discusses design considerations in two example areas. One is the design of cryopanels consisting of a pipe, centrally supplied with cryogenic helium, and a welded fin, passively cooled, to provide the necessary pumping surface below a given maximum temperature. The results of several parametric simulations in ANSYS are presented using different copper thicknesses and cryopanel geometries to discuss the thermal capability (heat transfer characteristics and heat capacities) of a number of design variants. The optimum design solution is based on copper-coated fins, using an electroplating technique, and thereby improving the heat transfer of the cryopanels while attaining an overall reduction in weight. The other area is the sound design of the manifold shielding system with a weld contact between copper and stainless steel. Weld samples were manufactured and investigated to raise awareness of the demands and risks during manufacturing and to demonstrate that readily applicable weld procedures exist.

Condition monitoring for a neutral beam injector cryopumping system

For neutral beam injection systems, the maintenance of a vacuum inside the injector box is essential for normal operation. Cryogenic pumping systems are often used to create and maintain this vacuum. Cryogenic pumping systems have been deployed on the neutral beam heating systems supporting the Joint European Torus. With these as a target application, the development of a condition monitoring scheme is presented. The scheme uses a residual generation approach. A bank of Kalman filters is used to estimate measured process variables. A residual evaluator is used to map residual signals onto a set of faults. Two example faults are simulated to demonstrate the response of the scheme. This paper contributes to the wider fusion development programme by demonstrating how a contemporary condition monitoring technique can be applied to a fusion support system, in order to improve its availability.

Channel electron multiplier operated on a sounding rocket without a cryogenic vacuum pump from 120 to 80 km altitude

We demonstrate that a channel electron multiplier (CEM) can be operated on a sounding rocket in the pulse-counting mode from 120km to 80km altitude without the cryogenic evacuation used in the past. Evacuation of the CEM is provided only by aerodynamic flow around the rocket. This demonstration is motivated by the need for additional flights of mass spectrometers to clarify the fate of metallic compounds and ions ablated from micrometeorites and their possible role in the nucleation of noctilucent clouds. The CEMs were flown as guest instruments on two sounding rockets to the mesosphere. Modeling of the aerodynamic flow around the payload with Direct Simulation Monte-Carlo (DSMC) code showed that the pressure is reduced below ambient in the void behind (relative to the direction of motion) an aft-facing surface. An enclosure containing the CEM was placed forward of an aft-facing deck and a valve was opened during flight to expose the CEM to the aerodynamically evacuated region behind it. The CEM operated successfully from apogee down to ∼80km. A Pirani gauge confirmed pressures reduced to as low as 20% of ambient with the extent of reduction dependent upon altitude and velocity. Additional DSMC simulations indicate that there are alternate payload designs with improved aerodynamic pumping for forward mounted instruments such as mass spectrometers.

収縮低減剤を混和したセメント硬化体の低温吸水効果による凍害劣化機構

For the formation of ice and its melting in the microstructure, Gibbs free energy for ice are lower than that of pore liquid. This results in the movement of water from fine pore to large pore and air voids. This phenomenon is so-called cryogenic suction pump. For coexistence of shrinkage reducing agent (SRA) in pore water, the movement of water into ice in air void is promoted by osmotic pressure effect as well as cryogenic suction pump effect. The authors used two different types of SRAs：one in the traditional one（SRA-1）, the other in the newly developed one（SRA-2）. The later in adsorbed strongly on cement was compared with traditional SRA-1. The authors prepared three different specimens of hardened cement paste（HCP：without SRA（OPC）, with SRA-1, with SRA-2. Length changes of HCP specimens increased with an increase of freezing/thawing cycles, and depended on the types of paste：SRA-1＞SRA-2＞OPC. However, the megascopic observation of frost damage did not correspond to the order of length changes：SRA-2＞SRA-1＝OPC. For the most serious damaged specimen added SRA-2, the gel pore less than 4nm increased during freezing/thawing cycles, where capillary pore decreased. The osmotic pressure due to present of SRA in pore liquid emptied the large gel pore and shrinkaged it providing increase of small gel pore. On the other hand, capillary pore was destroyed during freezing/thawing cycles, and then the capillary pore decreased. From these results, strong adsorbed SRA improves the resistance against frost damage, which is almost the same on specimens without SRA.本論文は、収縮低減剤が混和されたセメント硬化体の凍結融解劣化機構を解明するため、ギブス自由エネルギーの差によって働く低温吸水ポンプ作用と未凍結水移動の駆動力の増大によって気泡に隣接する毛細管空隙が断裂するという仮説を立て、凍結融解時の細孔構造変化及び長さ変化測定によって検証を行ったものである。その結果、収縮低減剤を混和したセメント硬化体において未凍結水の移動による毛細管空隙の収縮と比較的早いサイクルでひび割れが内部まで伝播したことを確認し、前述した仮説の妥当性を裏付けるとともに、収縮低減剤の種類によっては凍結融解抵抗性を損なわないことが確認された。

Design of Skid-Mounted LCNG Fueling Station for Vehicle

More and more LCNG fueling stations being built in several cities of China, it brings some problems on safety ensuring, rapidly constructing, cost saving, stable controlling, convenient moving. According to the requirements of the technological process, a kind of skid-mounted LCNG (Liquefied Compressed Natural Gas-engines) fueling station is designed. The station integrates those main equipments, such as LNG cryogenic pump, LNG vaporizer, and electrical control cabinet. Using a touch screen with a PLC in the electrical control cabinet, and it is an easy and less cost way to discharging the field controlling. The control system structure and the software are also designed for stable controlling. Compared to traditional CNG fueling station, it can be less land consumption, low construction cost, easily moving, and the skid-mounted LCNG fueling station has very wide application foreground.

1106 極低温ポンプの作製及び評価(磁気浮上・磁気ダンパ・超伝導)

1106 極低温ポンプの作製及び評価(磁気浮上・磁気ダンパ・超伝導)

Numerical simulation for the temperature environment of cryogenic pump

To improve performance and design of the cryogenic pump, analyze and solve the pump fault, and ensure the reliability of design and operating, it is highly necessary to understand the cryogenic pump temperature profile. Regarding horizontal single cryogenic centrifugal pump as the studied object, the flow field and structural heat transfer is calculated and analyzed. Based on reasonable boundary condition, three dimensional steady state of the pump mesh model is calculated by finite-element method with the software of Fluent, the fluid pressure field and the whole structural temperature profile is obtained. The structural temperature profile by finite-element heat transfer calculation indicates that: in the operating range of the cryogenic pump, the pumping cryogenic liquid is unable to vaporize at the room temperature, and the low temperature area is unable to interfere with the gear case in normal operation.

Study of Hydrogen Pumping through Condensed Argon in Cryogenic pump

In ultra high vacuum (UHV) range, hydrogen is a dominant residual gas in vacuum chamber. Hydrogen, being light gas, pumping of hydrogen in this vacuum range is limited with widely used UHV pumps, viz. turbo molecular pump and cryogenic pump. Pre condensed argon layers in cryogenic pump create porous structure on the surface of the pump, which traps hydrogen gas at a temperature less than 20° K. Additional argon gas injection in the cryogenic pump, at lowest temperature, generates multiple layers of condensed argon as a porous frost with 10 to 100 A° diameters pores, which increase the pumping capacity of hydrogen gas. This pumping mechanism of hydrogen is more effective, to pump more hydrogen gas in UHV range applicable in accelerator, space simulation etc. and where hydrogen is used as fuel gas like tokamak. For this experiment, the cryogenic pump with a closed loop refrigerator using helium gas is used to produce the minimum cryogenic temperature as ~ 14° K. In this paper, effect of cryosorption of hydrogen is presented with different levels of argon gas and hydrogen gas in cryogenic pump chamber.