Diffusion Pump Research Articles

On the Immersion Liquid Evaporation Method Based on the Dynamic Sweep of Magnitude of the Refractive Index of a Binary Liquid Mixture: A Case Study on Determining Mineral Particle Light Dispersion.

This is a feasibility study of a modified immersion liquid technique for determining the refractive index of micro-sized particles. The practical challenge of the traditional liquid immersion method is to find or produce a suitable host liquid whose refractive index equals that of a solid particle. Usually, the immersion liquid method uses a set of immersion liquids with different refractive indices or continuously mixes two liquids with different refractive indices, e.g., using a pumping system. Here, the phenomenon of liquid evaporation has been utilized in defining the time-dependent refractive index variation of the host liquid. From the spectral transmittance data measured during the evaporation process, the refractive index of a solid particle in the host liquid can be determined as a function of the wavelength. The method was tested using calcium fluoride (CaF2) particles with an immersion liquid mixed from diethyl ether and diffusion pump fluid. The dispersion data obtained were consistent with the literature values thus indicating the proper functioning of the proposed procedure.

Investigation of the 4-Quadrant behaviour of a mixed flow diffuser pump with CFD-methods and test rig evaluation

The complete pump characteristics including its 4-quadrant behaviour are of essential interest for off-design operations such as a pump trip. At this exceptional load case the pump enters the dissipation mode and moves further into the turbine mode while the direction of rotation and the flow direction will change. The time-consuming and expensive experimental investigation of the 4-quadrant behaviour requires a specific test rig, allowing the flow direction as well as the rotational direction of the investigated pump to be reverted. By measuring the pump performance (head and efficiency) at variable positive and negative discharge and rotation the complete pump characteristics are evaluated. Nowadays CFD- analysis allows for the reliable prediction of the hydraulic performance of a pump near the design point. However, abnormal operating conditions lead to complex and unsteady flow phenomena inside the pump. Besides steady-state calculations in the normal operating conditions quite comprehensive transient CFD-investigations are required to simulate the whole pump characteristics accurately. The present study focuses on the comparison of the results obtained on the test rig and by numerical methods and shows a remarkably good agreement between them. It can be shown that it is possible to reliably simulate the 4-quadrant behaviour of a mixed flow diffuser pump based on CFD-methods. Furthermore an exemplary waterhammer calculation shows the successful application of the numerically calculated 4- quadrant behaviour.

Angular dose variations from 320 kV rod pinch diode flash X-ray experiments on the modified Kali-1000 Pulsed Power System

This paper highlights the angular distribution of radiation dose emitted from a rod-pinch diode. The typical RP diode employed used a small diameter (1–2 mm) anode rod extended through a cathode aperture (5–8 mm). The diode chamber is maintained at 2 × 10–5 Torr vacuum by a rotary backed diffusion pump. Experiments performed on a modified Kali-1000 Pulsed Power System (300 kV, 30 kA, 100 ns) were aimed at optimizing the source by maximizing the figure of merit (dose at 1 m in rad/spot diameter2 in mm2) with minimizing of the diode impedance. The typical electron beam parameters used in the experiments are 240–320 kV, 6.5–27.5 kA, 100 ns, with a few hundreds of kA/cm2 current density. The radiation emitted from a rod-pinch diode is measured using thermoluminescence dosimeters at an angular interval of 15° on either side of the rod in horizontal and vertical plane with different aspects ratio ranging from 2.5 to 10.0. Experimentally found that the radiation dose produced from the rod pinch diode configuration is maximum in the axial direction and decreases with angular variation on either side of the axis in horizontal and vertical planes, which indicates the directivity of the source. Maximum radiation dose at 1 m distance on the axial line is ranging from 42 to 307 mR.

Advanced design of the Mechanical Tritium Pumping System for JET DTE2

For tritium processing in JET during the next Deuterium-Tritium-Experiment (DTE2), a fully tritium compatible and continuously working vacuum pumping system has been developed. This pump train will be used as roughing pump to cover a pressure regime between 10−1Pa and ambient pressure. Therefore, a two-stage liquid ring pump in combination with a booster vapor diffusion pump will be applied. In this paper, a close-to-final design of the pumps is being described. Finite element (FEM) simulation results of components where high mechanical stresses due to thermal gradients are expected are presented. Furthermore, the final design of the control and data acquisition system is shown and explained.

Flowing-gas diode pumped alkali lasers: theoretical analysis of transonic vs supersonic and subsonic devices.

We examine transonic diode pumped alkali laser (DPAL) devices as a simpler alternative to supersonic devices, suggested by B.D. Barmashenko and S. Rosenwaks [Appl. Phys. Lett. 102, 141108 (2013)], where complex hardware, including supersonic nozzle, diffuser and high power mechanical pump, is required for continuous closed cycle operation. Three-dimensional computational fluid dynamics modeling of transonic (Mach number M ~0.9) Cs and K DPALs, taking into account the kinetic processes in the lasing medium is reported. The performance of these lasers is compared with that of supersonic (M ~2.5) and subsonic (M ~0.2) DPALs. For Cs DPAL the maximum achievable power of transonic device is lower than that of supersonic, with the same resonator and Cs density at the laser section inlet, by only ~3% implying that supersonic operation mode has only small advantage over transonic. On the other hand, for subsonic laser the maximum power is by 7% lower than in transonic, showing larger advantage of transonic over subsonic operation mode. The power achieved in supersonic and transonic K DPALs is higher than in subsonic by ~80% and ~20%, respectively, showing a considerable advantage of supersonic device over transonic and of transonic over subsonic.

Construction of Home-Made Tin Fixed-Point Cell at TUBITAK UME

TUBITAK UME Temperature Laboratory initiated a new study which focuses on the construction of a tin freezing-point cell as a primary temperature standard. The design is an open-cell type similar to the National Institute of Standards and Technology design. With this aim, a brand new vacuum and filling line employing an oil diffusion pump and two cold traps (liquid nitrogen and dry ice) was set-up. The graphite parts (crucible, thermometer well, etc.) have been baked at high temperature under vacuum. Each cell was filled with approximately 1 kg of high-purity tin (99.9999 %) in a three-zone furnace. Then several melting and freezing curves were obtained to assess the quality of the home-made cell, and also the new cell was compared with the existing reference cell of the laboratory. The results obtained are very close to the reference cell of UME, indicating that the method used for fabrication was promising and satisfactory and also seems to meet the requirements to have a primary level temperature standard.

Development of a standard gas generating vial comprised of a silicon oil–polystyrene/divinylbenzene composite sorbent

In this work, a highly reproducible standard gas generating vial is proposed. The vial is comprised of a silicon diffusion pump oil spiked with an appropriate calibration compound, such as modified McReynolds probes (benzene, 2-pentanone, pyridine, 1-nitropropane, 1-pentanol, and n-octane), and then mixed with polystyrene/divinylbenzene (PS/DVB) particles. The concentrations of these compounds in gaseous headspace were found to substantially decrease in comparison to previously developed hydrocarbon pump oil based vials; hence, the amount of standard loaded onto SPME fibers was at most, half that of the previous vial design. Depletion for all compounds after 208 successive extractions was shown to be less than 3.5%. Smaller quantities of standards being used resulted in a vial that depleted slower while remaining statistically repeatable over a wider number of runs. Indeed, it was found that depletion could be largely predicted by using a mass balance theoretical model. This behavior allowed a further increase in the number of loadings that could be performed repeatedly. At a 95% level of confidence, the ANOVA test demonstrated that the prepared vials were statistically identical, with no significant intra- or inter-batch differences. In addition, it was found that vials stored under different conditions (e.g. under light exposure, room temperature, and within a refrigerator) were stable over 10 weeks. Silicon based vials proved to be ideal for performing instrument quality control and loading of internal standards onto fibers, both of which are of great importance when performing on-site analysis using portable GC–MS instrumentation and high throughput determinations in laboratory.

Experimental investigation of velocity fluctuations in a radial diffuser pump

The strong interaction in a radial pump due to the relative movement between the impeller and the diffuser may excite not only strong pressure fluctuations but also velocity fluctuations. In this paper, the laser Doppler velocimetry (LDV) technique is successfully applied to measure the periodic flow field in a radial diffuser pump with low-specific speed, in order to investigate the velocity fluctuations caused by the impeller-diffuser interactions both in the impeller and diffuser regions. The velocity fluctuations in the impeller region are quantitatively examined at different radial positions, and the flow structure at the radial gap between two flow components is analyzed at different relative positions. In addition, the downstream effect on the diffuser flow is quantitatively and qualitatively assessed and compared with the turbulence effect.

Experimental Investigation on Turbulence Fields in a Radial Diffuser Pump Using PIV Technique

Particle image velocimetry (PIV) technique has been successfully employed to measure the unsteady periodic flow in a lowspecific speed radial diffuser pump, in order to obtain turbulence intensity fields caused by rotor-stator interaction at different operation conditions. The PIVmeasuring region covers a complete impeller channel and a complete diffuser channel, enabling the investigation of turbulence behavior in both the impeller and diffuser region simultaneously, and the turbulence transportation from the upstream impeller wake to the diffuser region. In addition, the flow rate effect on the turbulence field has also been investigated by comparing measured turbulence fields at different flow rates in both qualitative and quantitative manners. This work can enhance the understanding of turbulence generation mechanism, transport behavior, and development characteristics in rotor-stator interaction in vaned radial diffuser pumps.

The Effect of Thickness of Aluminium Films on Optical Reflectance

In Uganda and Africa at large, up to 90% of the total energy used for food preparation and water pasteurization is from fossil fuels particularly firewood and kerosene which pollute the environment, yet there is abundant solar energy throughout the year, which could also be used. Uganda is abundantly rich in clay minerals such as ball clay, kaolin, feldspar, and quartz from which ceramic substrates were developed. Aluminium films of different thicknesses were deposited on different substrates in the diffusion pump microprocessor vacuum coater (Edwards AUTO 306). The optical reflectance of the aluminium films was obtained using a spectrophotometer (SolidSpec-3700/DUV-UV-VIS-NIR) at various wave lengths. The analysis of the results of the study revealed that the optical reflectance of the aluminium films was above 50% and increased with increasing film thickness and wavelength. Thus, this method can be used to produce reflector systems in the technology of solar cooking and other appliances which use solar energy.

1203 ディフューザポンプ翼列干渉により誘起される共鳴現象

1203 ディフューザポンプ翼列干渉により誘起される共鳴現象

Contamination of Magnetron Sputtered Metallic Films by Oxygen From Residual Atmosphere in Deposition Chamber

The article reports on the contamination of Ag thin films sputtered from a pure Ag target in Ar and Ne gas by the RF magnetron by gas atoms contained in residual gas atmosphere in the deposition chamber at different values of the base pressure. The amount of O atoms generated at different values of base pressure is compared with the amount of Ag atoms sputtered at different deposition rates of Ag film. This comparison reveals a great problem in the formation of pure metallic films at low deposition rates and high values of the base pressure. No pure Ag films can be deposited at low in deposition chambers evacuated with diffusion or root pumps to the base pressures lower than 1 mPa only.

Synthesis and Characterization of Fluorinated Alkyl Substituted Disiloxane

Alkyl substituted disiloxanes demonstrated promising applications as high performance hydraulic oil, diffusion pump oil, etc. In this study, fluorinated alkyl substituted disiloxane was synthesized via Grignard reaction followed by condensation reaction. Its chemical structure was verified by FTIR and NMR. Measurement results showed that this silicon oil exhibited good high temperature performance, oxidation resistance and rust resistance.

Electrical resistivity and its thermal coefficient of TiW alloy thin films prepared by two different sputtering systems

AbstractElectrical resistivity and its thermal coefficient (TCR) of TiW alloy thin films which were prepared by using two different sputtering systems have been investigated. System A is a DC‐magnetron sputtering system equipped with a single composite‐target that allows the contents controllable by an external field of solenoid as reported in previous papers (Sakurai and Takeda, Abstract of E‐MRS 2005 Fall Meeting [1] and Sakurai et al., Solid State Phenom. 154, 175 (2009) [2]). The system A prepared specimens with the range of 21.6 to 36.6 at% of W‐contents. The TCR varies from minus to plus at 32 at% of W‐content. On the other hand, System B is a RF‐magnetron sputtering system equipped with multi‐targets and multi‐sputtering‐sources. The system B covered the whole binary composition ranges by controlling power ratio for two independent sputtering sources. The resistivity characteristics show a parabolic curve with the maximum value on Ti‐rich contents. The TCR decreases at the contents that shows the maximum resistivity, but the TCR is always plus and does not cross zero. Difference of the properties by using the two systems will be discussed. In the system A, the background is exhausted by an oil diffusion pump and the pressure is higher (lower vacuum degree) than the background in the system B with a turbo molecular pump. This suggests that zero TCR would be achieved by introducing the controlled impurities (O2 or N2) into the binary alloy films. (© 2014 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)

The KALPUREX-process – A new vacuum pumping process for exhaust gases in fusion power plants

The Karlsruhe Institute of Technology (KIT) is developing a continuously working and non-cryogenic pumping solution for torus exhaust pumping of a demonstration power plant (DEMO) including Direct Internal Recycling (DIR).This full pumping system consists of three pumps, namely a metal foil pump for gas separation, a linear diffusion pump as primary pump and a liquid ring pump as backing pump. The latter two pumps apply mercury as working fluid due to its perfect tritium compatibility. This asks for a baffle system on both sides of the pumping train to control working fluid vapour and to avoid any mercury propagation in the machine.In this paper, the arrangement of all torus pumps required for a power plant reactor as well as the corresponding infrastructure and its effect on the DEMO machine design is presented and discussed. The full pumping process is called ‘Karlsruhe liquid metal based pumping process for fusion reactor exhaust gases’ (KALPUREX process, patent pending).

A sub-nanosecond rise time intense electron beam source

This paper presents the design and development of a 75 kV, 55 A, 2 nanosecond duration, ⩽ 850 ps rise time, single shot,intense ( ⩾ 100 A/cm2) electron beam source and also themeasurement technique adopted in sub-nanosecond regime. A 200 kV (nanosecondpulse) coaxial pulse forming line (PFL) based pulser is designed to drive acold cathode explosive emission electron gun. The electron gun diodeconsists with a planer graphite cathode, which has the emission area of 8 mmdiameter and a SS 304L anode mesh. Vacuum is achieved of the order of 3.5e-5 mbar by using a diffusion pump, backed by rotary pump. At the diagnosticside for diode voltage measurement a fast response copper sulphate aqueoussolution resistive voltage divider is designed and implemented. For the beamcurrent diagnostic a graphite Faraday cup is designed with taking care ofresponse time in GHz (1.0–3.0 GHz) regime. The circuit diagram, voltage andcurrent waveforms and the experimental setup is presented.

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.

Analysis of High Vacuum System Based on the Applications of Vacuum Materials

In this study, the outgassing effects of selected vacuum materials on the vacuum characteristics were simulated by the VacSim Multi simulation tool. This investigation examined the feasibility of reliably simulating the outgassing characteristics of common vacuum chamber materials (aluminum, copper, stainless steel, nickel plated steel, Viton A). The optimum design factors for these vacuum systems were suggested based on the simulation results. The baking- out effects of the modeled systems and materials on the performance of the vacuum system were also analyzed. The simulation predicted that the overall outgassing effect was more significant in the turbomolecular pump system than in the diffusion pump system and that the utilization of a booster pump has a greater effect on the evacuation time than on the ultimate pressure.

Vacuum chamber-free centrifuge with magnetic bearings

Centrifuges are devices that separate particles of different densities and sizes through the application of a centrifugal force. If a centrifuge could be operated under atmospheric conditions, all vacuum-related components such as the vacuum chamber, vacuum pump, diffusion pump, and sealing could be removed from a conventional centrifuge system. The design and manufacturing procedure for centrifuges could then be greatly simplified to facilitate the production of lightweight centrifuge systems of smaller volume. Furthermore, the maintenance costs incurred owing to wear and tear due to conventional ball bearings would be eliminated. In this study, we describe a novel vacuum chamber-free centrifuge supported by magnetic bearings. We demonstrate the feasibility of the vacuum chamber-free centrifuge by presenting experimental results that verify its high-speed support capability and motoring power capacity.

Fluid-Structure Interaction Study on Diffuser Pump With a Two-Way Coupling Method

In order to study the effect of the fluid-structure interaction (FSI) on the simulation results, the external characteristics and internal flow features of a diffuser pump were analyzed with a two-way flow solid coupling method. And the static and dynamic structure analysis of the blade was also caculated with the FEA method. The steady flow field is based on Reynolds Averaged N-S equations with standard <TEX>$k-{\varepsilon}$</TEX> turbulent model, the unsteady flow field is based on the large eddy simulation, and the structure response is based on elastic transient structural dynamic equation. The results showed that the effect of FSI on the head prediction based on CFD really exists. At the same radius, the van mises stress on the nodes closed shroud and hub was larger than other nodes. A large deformation region existed near inlet side at the middle of blades. The strength of impeller satisfied the strength requirement with static stress analysis based on the fourth strength theory. The dynamic stress varied periodically with the impeller rotating. It was also found that the fundamental frequency of the dynamic stress is the rotating frequency and its harmonic frequency. The frequency of maximum stress amplitude at node 1626 was 7 times of the rotating frequency. The frequency of maximum stress amplitude at node 2328 was 14 times of the rotating frequency. No matter strength failure or fatigue failure, the root of blades near shroud is the key region to analyse.