Search

In nuclear reaction experiments, the thin targets are required. In the present work, 30 thin 116Sn targets were prepared using physical vapor deposition technique (preferable for thin film fabrication) on carbon backing with usage efficiency of 98%. The carbon-backed thin target films along with the parting agents are deposited on the particular substrates using a diffusion pump based coating unit. The thicknesses of the targets were verified using α-energy loss and RBS technique and they were in good agreement with each other. The purity of the target, verified using RBS, EDS and XRD techniques, were also tested with confirmation.

Sandwiched 142 , 150 Nd targets of thickness ( ∼ 100– 150 μ g /cm 2 ) have been fabricated between two carbon layers of different thickness ( ∼ 30 μ g /cm 2 and ∼ 10 μ g /cm 2 ) using the thermal evaporation technique in the diffusion pump based coating unit at the target lab of Inter University Accelerator Center (IUAC), New Delhi. Thickness and purity measurement of the targets have been confirmed by using the Rutherford backscattering spectrometry (RBS) technique and energy dispersive X-ray fluorescence (EDXRF) measurement present at IUAC, New Delhi and Panjab University, Chandigarh, respectively. These targets have been successfully used in a recent experiment to measure evaporation-residue (ER) cross section and spin distribution of ERs in the hybrid recoil mass analyzer (HYRA) facility present at IUAC.

To perform nuclear reaction experiments at HIRA, IUAC, New Delhi, thin (100–150 μg/cm2) and pure 61,62Ni targets of uniform thickness are required. Self supporting targets are preferable for such case but, instead, carbon-backed isotopic targets are fabricated by adapting physical vapour deposition technique as it was comparatively more stable and consistent. Around 25 thin targets of both 61,62Ni isotopes are prepared using the limited amount of available enriched target material (less than 100 mg). The carbon-backed slides along with the parting agents are prepared using a diffusion pump based coating unit and the target material is deposited over the carbon-backed slides in the turbopump based coating unit. To obtain consistent and intact targets, some trials were done with deposited slides and was found that the material degrades in any of the slides when kept idle for few days. The thicknesses of the targets are verified using profilometer, α energy loss technique, and RBS technique. They were found to be in good agreement with each other using the three techniques. The purity and the uniformity of the fabricated targets are further confirmed after verification using the RBS, the EDS and the XRD techniques.

Isotopic 121Sb targets with 197 Au backing have been prepared by Physical Vapor Deposition (PVD) method using the diffusion pump based coating unit at target laboratory, Inter University Accelerator Centre (IUAC), New Delhi, India. The target thickness was measured by stylus profilo-meter and the purity of the targets was investigated by Energy Dispersive X-ray Analysis (EDXA). One of these targets has been used in an experiment which was performed at IUAC for nuclear structure study through fusion evaporation reaction. The excitation function of the 121Sb(12C, y x n γ ) reaction has been performed for energies 58 to 70 MeV in steps of 4 MeV. The experimental results were compared with the calculations of statistical models : PACE4 and CASCADE. The methods adopted to achieve best quality foils and good deposition efficiency are reported in this paper.

The vortex pump has increasingly become an important alternative or supplement to the centrifugal pump, the positive displacement pump and the diffusion pump due to its capacity of developing a high head at a small flow rate within a single stage. However, the vortex pumps with various blade shapes such as the twisted blades or the 3-D blades are not well studied. In this paper, some new concepts of the 2-D and 3-D corner blades are introduced for the design of the vortex pumps. The mechanism behind the effect of the corner blade shapes on the pump hydraulic performance is numerically investigated and elucidated in terms of the internal vortex structures. The results show that both 2-D and 3-D forward corner blades can induce stronger well-organized longitudinal vortices as well as smaller axial and radial vortices within the impeller blade passage, which benefit a higher pump head and a higher efficiency in comparison with the traditional radial straight blade. This study provides useful guidelines for the design of advanced vortex pumps.

The linear mercury diffusion pump is proposed as the primary pump for sustaining the continuous working of KALPUREX (Karlsruhe liquid metal based pumping process for fusion reactor exhaust gases), which is considered as the exhaust pumping solution for reducing the tritium inventory in future fusion reactor with the fuel cycle based on the Direct Internal Recycling (DIR) concept. In this work, a preliminary simulation study of the linear mercury diffusion pump (LDP) is performed based on the Direct Simulation Monte Carlo (DSMC) method. While the dsmcFoam solver in the OpenFOAM platform is used, the inlet model named by fixed mass-flow-rate (FixedMFR) model is developed to control the mass flow rate into the pump, in accord with the condition of the experiment in 1950s. The simulated pumping speeds are in reasonable agreement with the experimental results when the pressure is in the range of 1 × 10−2 ~ 2 × 10−2 Pa, which implies that the DSMC model can be used for simulating the performance of the LDP. It should be noted that in the preliminary DSMC model, the mesh size is too large. Due to the large mesh size, the expansion of the mercury vapor steam is overestimated and the pumping speed is underestimated. Further work is required to find a proper way to generate the computational mesh for predicting the pumping performance of the LDP accurately and effectively.

The dropper-type gas flow measuring apparatus is widely used in the vacuum pumping speed measurement. An innovative method based on the weighing principle was proposed in the paper. The structure and working principle of the dropper-type gas flow measuring apparatus is introduced. An electronic scale was placed under the storage tank to measure the oil mass into dropper. The corresponding formulas of gas flow are deduced and the error analysis of measuring accuracy is carried out. Comparing to the disadvantages of the original measuring method, the characteristics of new method was analyzed. A miniature measuring apparatus was set up in the laboratory, and the pumping speed curve of a K-200 diffusion pump was measured by experiment. The feasibility and convenience of the measuring apparatus were verified. This improvement can provide theoretical support and reference method for achieving automatic measurement of vacuum pumping speed and minimal gas flow.

High-intensity pulsed ion beam (HIPIB) technology is developed as an advanced manufacturing method for components with improved wear, corrosion and/or fatigue performance, etc. Robust HIPIB equipment with stable repetitive operation, long-lifetime, and easy maintenance are desired for industrial applications, on which stability of ion beam parameters is critical to achieve consistent result of reproducibility. Here, magnetically insulated ion diodes (MIDs) as ion source with durable graphite anode are investigated in a simple self-magnetic field configuration under repetitive operation. Influence of background pressure on ion beam generation and transportation is emphasized since ion beam sources were intrinsically a vacuum-based system. Comparative experiments were conducted on two types of HIPIB equipment, that is, TEMP-6 and TEMP-4M, differing in vacuum packages where turbo-molecular pump or oil diffusion pump was used. Both the HIPIB equipments are operated on a bipolar pulse mode, that is, a first negative pulse of 150–200 kV with pulse duration 450–500 ns to generate anode plasma on explosive electron emission, and a second positive pulse of 200–250 kV with 120 ns to accelerate the ions. Ion beam energy density up to 8 J/cm2 is achievable using MIDs of geometrical focusing configuration, and the total energy, energy density distribution along cross-section, deflection and divergence, and charge neutralization of the ion beams are assessed under background pressures in a wide range of two orders of magnitude, that is, 1–100 mPa. No appreciable change in the parameters is observed up to 50 mPa, and merely a slight increase in the beam deflection from about ±3 mm to about ±4 mm at the focal point over 50 mPa. The stability of ion beam at the varied pressure is mainly facilitated by the higher pressure up to several Pa in anode–cathode gap during plasma generation and good neutralizing effect for ion beam transportation.

Several mercury diffusion pump stages in the Tritium Purification process at the Savannah River Site (SRS) have been removed from service for scheduled preventive maintenance. These stages have been examined to determine if failure has occurred. Evidence of fatigue around the flange portion of the pump has been seen. In addition, erosion and cavitation inside the throat of the venturi tube and corrosion on the other surface of the venturi tube has been observed. Several measures are being examined in an attempt to improve the performance of these pumps. These measures, as well as the noted observations, are described. Six stages [two machined (MP) and four electron beam (EB) welded] from the mercury diffusion pumps operating in the Tritium Purification process at SRS have been analyzed to determine their condition after nine months of usage. Several cracks were found around the necked region of the two MP stages. The EB welded stages, however, seemed to perform better in service; only two of four stages showed cracking. The cracking is caused by fatigue that has been enhanced by high stresses and tritium in the flange area. The EB welded stage appears to be a step in the right direction. Since the EB weld is a shrink fit, the surface is in compression, thereby eliminating crack propagation. In addition, shot peening has been employed to produce a compressive material surface since fatigue usually originates at the surface. Pitting was observed down the throat of the venturi. This pitting was caused by cavitation and erosion along the length of the venturi tube. Corrosion and pitting was seen on the exterior walls of the diffuser tubes. Stress-corrosion cracks were observed emanating from these corrosion pits. The corrosion likely occurred from the chloride ions present in the process cooling water. Shot peening is now being used in an attempt to place the outside of the diffuser tube in compression to eliminate the stress-corrosion cracking.

There has been a high demand for low-cost thermal vacuum testing facility for Lean satellite (1U CubeSat) program in emerging space economies. Most often, CubeSat testing is performed in a complex and expensive thermal vacuum chamber equipped with for example shroud filled liquid nitrogen (boiling point is-195.7oC) for simulating the cold temperature environment as close to the cold heat sink of outer space in a simulated low pressure (>10-3 Pa) chamber environment. This paper introduces PeTT vacuum chamber as a low cost and easy access testing facility suitable for simulating cold temperature plateaus for performing a functional test of the internal subsystems of Lean satellite (1U CubeSat) functional test. Under ISO 19683: “Design Qualification and Acceptance Test of Spacecraft and Units”, the test requirement for cold temperature plateau is equal to - or more than -15oC. The PeTT vacuum chamber has been developed to achieve ISO 19683 test requirements. The PeTT vacuum chamber consists of a Peltier cooling device integrated inside a vacuum chamber. The Peltier cooling device consists of 4multi-stage Peltier elements sandwiched in-between a copper surface plate and water cooler has a mass of 3.4kg and size 152mm length × 127mm width × 40 mm height. The Peltier cooling device is targeted for performing 1U Cubesat functional test by conduction heat transfer. The Peltier cooling device has a total maximum exchange heat capability of 400W which runs by water cooling system and varying DC power supply. The vacuum chamber has an inner diameter of 55cm equipped with a rotary pump and diffusion pump to achieve a low pressure around 10–4 Pa. The main goal of this paper is to provide low cost and easy access testing technique for space activities in emerging space economies especially universities space research and development laboratories, to build their capacity in the installation and operation of a thermal vacuum testing facility. This paper provides details of the design and development of the PeTT vacuum chamber, cost, and results for testing 1U dummy CubeSat.

The fabrication of targets from rare earth elements are extremely difficult due to their highly active reacting properties. Hence, the fabrication, transfer, and storage of these types of targets using in-vacuum transfer facilities is found to be the ideal solution. However, the required instrument for this purpose is very expensive and not easy to maintain for a long period of time. Search for an alternate simplified method and its effective usage for fabrication and preservation of rare earth targets is the need of the hour. The present manuscript describes such a method which has been successfully used in the case of fabricating thin targets from the enriched Neodymium (Nd) isotopes. Since the target materials of enriched Nd-isotopes are expensive, devising a procedure which can produce a maximum number of targets with the use of minimum amount of material is very important. Isotopically enriched thin, uniform and durable Neodymium ( 142 , 150 Nd) targets of ∼ 150 μ g /cm 2 thickness have been fabricated by using electron beam bombardment technique within a diffusion pump based High Vacuum (HV) coating unit. The targets have been fabricated at the target laboratory of the Inter University Accelerator Centre (IUAC), New Delhi. The sandwiched targets have been prepared with a carbon backing layer of thickness ∼ 25 μ g /cm 2 and a carbon capping layer of thickness ∼ 10 μ g /cm 2 . The present article brings out different aspects such as: (i) the detailed fabrication procedure along with the various challenges faced (heat damage, peeling off, oxidizing nature of the target etc.) has been reported in this article; (ii) the measurements involving Energy Dispersive X-ray Spectroscopy (EDS), and Rutherford Backscattering Spectrometry (RBS) have been carried out to assess the purity, uniformity, and elemental composition of the targets. The analysis of the acquired data from the measurements suggests that the prepared targets are found to be free from any high-Z contaminating elements. These targets have successfully been used in heavy-ion induced nuclear physics experiments using the General Purpose Scattering Chamber (GPSC) available at IUAC, New Delhi.

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.

We demonstrate a hydrogel bowl capable of selectively and rapidly collecting spilled oil while floating on water. The bowl has macroscopic openings in its sidewall, and its surface is first coated with octadecyltrichlorosilane (OTS) and then with diffusion pump oil, which imparts exceptional hydrophobic, oleophilic, and high oil wettability properties. The use of a hydrogel makes it possible to obtain surface hydrophobicity and oleophilicity, while also being inexpensive, eco-friendly, and easy to fabricate. Using a prototype of the bowl and a small pump system, we demonstrate that oils with a broad range of viscosities (2.7–2000.0 cSt at 20–40 °C) are more rapidly and efficiently collected from the surface of both pure water and seawater than with any other reported technique. The hydrogel bowl can collect oil for more than one month without losing its efficiency and can be stored in oil for reuse. Therefore, such hydrogel bowls represent a new alternative to conventional oil spill remediation techniques.

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.

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.

This work presents the results of the experimental study of a method of liquid propellant supply by the means of a porous ceramic diffusion element placed in a coaxial discharge unit. Diffusion pump oil is used as a propellant. Supply rate of liquid to the discharge area is controlled by the pressure at the back side of the porous element. Plasma flow is generated by discharge initiated by 30 ns pulses of 3.5 kA current at initial voltage of 90 kV. Measured parameters are weight loss and ion current of the plasma bunch. We show that the discharge in such experimental conditions is localized within a layer of liquid on a surface of porous ceramics. Plasma formation efficiency depends on thickness of the liquid layer, being higher in case of thinner layers.

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).

Electrical 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 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.