WorldWideScience

Sample records for previous ultrahigh vacuum

  1. Advanced Photon Source accelerator ultrahigh vacuum guide

    International Nuclear Information System (INIS)

    Liu, C.; Noonan, J.

    1994-03-01

    In this document the authors summarize the following: (1) an overview of basic concepts of ultrahigh vacuum needed for the APS project, (2) a description of vacuum design and calculations for major parts of APS, including linac, linac waveguide, low energy undulator test line, positron accumulator ring (PAR), booster synchrotron ring, storage ring, and insertion devices, and (3) cleaning procedures of ultrahigh vacuum (UHV) components presently used at APS

  2. Design consideration on the synchrotron ultrahigh vacuum system

    International Nuclear Information System (INIS)

    Tsujikawa, H.; Chida, K.; Mizobuchi, A.; Miyahara, A.

    1982-01-01

    Ultrahigh vacuum production for the high-energy heavy-ion accelerator poses special problems concerning beam-gas molecule and beam-wall interactions. In this paper, summary of the TARN ultrahigh vacuum system and design criteria of the synchrotron ultrahigh vacuum system are presented. On-beam pressure of 4 x 10 -11 Torr is achieved in the TARN ultrahigh vacuum system, of which experiences through the construction and the operation are described and discussed. With emphasis on the application of newly developed technique in the fabrication of vacuum chamber and ultrahigh vacuum pump for the synchrotron ultrahigh vacuum system. (author)

  3. Automatic electromagnetic valve for previous vacuum

    International Nuclear Information System (INIS)

    Granados, C. E.; Martin, F.

    1959-01-01

    A valve which permits the maintenance of an installation vacuum when electric current fails is described. It also lets the air in the previous vacuum bomb to prevent the oil ascending in the vacuum tubes. (Author)

  4. Molecular density modulation type ultrahigh vacuum gauge

    International Nuclear Information System (INIS)

    Horikoshi, Gen-ichi; Komada, Kazutaka; Mizuno, Hajime

    1978-01-01

    When pressure is measured in ultrahigh vacuum region, with an ionization gauge one of the causes producing the measuring limit is its dark current due to so-called soft X-ray effect and ion desorption. A kind of the modulation gauge provided with a modulation electrode is described in this paper. If a plate is vibrating perpendicularly to its surface in the sufficiently low pressure gas to satisfy molecular conditions (molecular density n), the molecular density in the space in front of the plate is expected to vary with time, affected by the vibration of the plate. When the vacuum gauge is placed in this space, the modulated current is proportional to pressure P, which is not related to the current due to soft X-ray effect and ion desorption. The other cause of determining the pressure-measuring limit is noises, among which only the noise coherent with the vibration of the plate affects the measurement. To avoid the induced current by this type of noise, it is considered to use the pulse-counting technique using an electron multiplier. It is anticipated that the induced currents generated from electrical noises and mechanical vibrations can be avoided almost completely by this method. As a result, the theoretical measuring limit may be estimated at approximately 5 x 10 -13 Torr, if the mean residence time in the collision of molecules with the plate is assumed to be 1 sec, the sensitivity of the vacuum gauge S is 20 Torr -1 , electron current Ie is 2 x 10 -3 A and modulation coefficient m is 3 x 10 -3 . (Wakatsuki, Y.)

  5. Modification of Ultra-High Vacuum Surfaces Using Free Radicals

    CERN Document Server

    Vorlaufer, G

    2002-01-01

    In ultra-high vacuum systems outgassing from vacuum chamber walls and desorption of surface adsorbates are usually the factors which determine pressure and residual gas composition. In particular in beam vacuum systems of accelerators like the LHC, where surfaces are exposed to intense synchrotron radiation and bombardment by energetic ions and electrons, surface properties like the molecular desorption yield or secondary electron yield can strongly influence the performance of the accelerator. Well-established treatment methods like vacuum bake-out or glow-discharge cleaning have been successfully applied in the past to condition ultra-high vacuum surfaces, but these methods are sometimes difficult to carry out, for example if the vacuum chambers are not accessible. In this work, an alternative treatment method is investigated. This method is based on the strong chemical reactivity of free radicals, electrically neutral fragments of molecules. Free radicals (in the case of this work, nitrogen and oxygen radi...

  6. High resolution, high speed ultrahigh vacuum microscopy

    International Nuclear Information System (INIS)

    Poppa, Helmut

    2004-01-01

    The history and future of transmission electron microscopy (TEM) is discussed as it refers to the eventual development of instruments and techniques applicable to the real time in situ investigation of surface processes with high resolution. To reach this objective, it was necessary to transform conventional high resolution instruments so that an ultrahigh vacuum (UHV) environment at the sample site was created, that access to the sample by various in situ sample modification procedures was provided, and that in situ sample exchanges with other integrated surface analytical systems became possible. Furthermore, high resolution image acquisition systems had to be developed to take advantage of the high speed imaging capabilities of projection imaging microscopes. These changes to conventional electron microscopy and its uses were slowly realized in a few international laboratories over a period of almost 40 years by a relatively small number of researchers crucially interested in advancing the state of the art of electron microscopy and its applications to diverse areas of interest; often concentrating on the nucleation, growth, and properties of thin films on well defined material surfaces. A part of this review is dedicated to the recognition of the major contributions to surface and thin film science by these pioneers. Finally, some of the important current developments in aberration corrected electron optics and eventual adaptations to in situ UHV microscopy are discussed. As a result of all the path breaking developments that have led to today's highly sophisticated UHV-TEM systems, integrated fundamental studies are now possible that combine many traditional surface science approaches. Combined investigations to date have involved in situ and ex situ surface microscopies such as scanning tunneling microscopy/atomic force microscopy, scanning Auger microscopy, and photoemission electron microscopy, and area-integrating techniques such as x-ray photoelectron

  7. Ultra-high vacuum technology for accelerators

    CERN Multimedia

    CERN. Geneva. Audiovisual Unit; Hilleret, Noël; Strubin, Pierre M

    2002-01-01

    The lectures will start with a review of the basics of vacuum physics required to build Ultra High Vacuum (UHV) systems, such as static and dynamic outgassing. Before reviewing the various pumping and measurement devices, including the most modern one like Non Evaporable Getter (NEG) coatings, an overview of adequate materials to be used in UHV systems will be given together with their treatment (e.g. cleaning procedures and bake out). Practical examples based on existing or future accelerators will be used to illustrate the topics. Finally, a short overview of modern vacuum controls and interlocks will be given.

  8. Automatic kelvin probe compatible with ultrahigh vacuum

    NARCIS (Netherlands)

    Baikie, I.D.; van der Werf, Kees; Oerbekke, H.; Broeze, J.; van Silfhout, Arend

    1989-01-01

    This article describes a new type of in situ ultrahigh‐vacuum compatible kelvin probe based on a voice‐coil driving mechanism. This design exhibits several advantages over conventional mechanical feed‐through and (in situ) piezoelectric devices in regard to the possibility of multiple probe

  9. An ultrahigh vacuum monochromator for photophysics beamline

    International Nuclear Information System (INIS)

    Meenakshi Raja Rao, P.; Padmanabhan, Saraswathy; Raja Sekhar, B.N.; Shastri, Aparna; Khan, H.A.; Sinha, A.K.

    2000-08-01

    The photophysics beamline designed for carrying out photoabsorption and fluorescence studies using the 450 MeV Synchrotron Radiation Source (SRS), INDUS-1, uses a 1 metre monochromator as premonochromator for monochromatising the continuum. An ultra high vacuum compatible monochromator in Seya-Namioka mount has been designed and fabricated indigenously. The monochromator was assembled and tested for its performance. Wavelength scanning mechanism was tested for its reproducibility and the monochromator was tested for its resolution using UV and VUV sources. An average spectral resolution of 2.5 A was achieved using a 1200 gr/mm grating. A wavelength repeatability of ± 1A was obtained. An ultra high vacuum of 2 X 10 -8 mbar was also achieved in the monochromator. Details of fabrication, assembly and testing are presented in this report. (author)

  10. Ultra-high vacuum photoelectron linear accelerator

    Science.gov (United States)

    Yu, David U.L.; Luo, Yan

    2013-07-16

    An rf linear accelerator for producing an electron beam. The outer wall of the rf cavity of said linear accelerator being perforated to allow gas inside said rf cavity to flow to a pressure chamber surrounding said rf cavity and having means of ultra high vacuum pumping of the cathode of said rf linear accelerator. Said rf linear accelerator is used to accelerate polarized or unpolarized electrons produced by a photocathode, or to accelerate thermally heated electrons produced by a thermionic cathode, or to accelerate rf heated field emission electrons produced by a field emission cathode.

  11. Historical evolution toward achieving ultrahigh vacuum in JEOL electron microscopes

    CERN Document Server

    Yoshimura, Nagamitsu

    2014-01-01

    This book describes the developmental history of the vacuum system of the transmission electron microscope (TEM) at the Japan Electron Optics Laboratory (JEOL) from its inception to its use in today’s high-technology microscopes. The author and his colleagues were engaged in developing vacuum technology for electron microscopes (JEM series) at JEOL for many years. This volume presents a summary and explanation of their work and the technology that makes possible a clean ultrahigh vacuum. The typical users of the TEM are top-level researchers working at the frontiers of new materials or with new biological specimens. They often use the TEM under extremely severe conditions, with problems sometimes occurring in the vacuum system of the microscopes. JEOL engineers then must work as quickly as possible to improve the vacuum evacuation system so as to prevent the recurrence of such problems. Among the wealth of explanatory material in this book are examples of users’ reports of problems in the vacuum system of...

  12. Quartz microbalance device for transfer into ultrahigh vacuum systems

    International Nuclear Information System (INIS)

    Stavale, F.; Achete, C. A.; Niehus, H.

    2008-01-01

    An uncomplicated quartz microbalance device has been developed which is transferable into ultrahigh vacuum (UHV) systems. The device is extremely useful for flux calibration of different kinds of material evaporators. Mounted on a commercial specimen holder, the device allows fast quartz microbalance transfer into the UHV and subsequent positioning exactly to the sample location where subsequent thin film deposition experiments shall be carried out. After backtransfer into an UHV sample stage, the manipulator may be loaded in situ with the specimen suited for the experiment. The microbalance device capability is demonstrated for monolayer and submonolayer vanadium depositions with an achieved calibration sensitivity of less the 0.001 ML coverage.

  13. Surface chemistry of tribochemical reactions explored in ultrahigh vacuum conditions

    International Nuclear Information System (INIS)

    Lara-Romero, Javier; Maya-Yescas, Rafael; Rico-Cerda, Jose Luis; Rivera-Rojas, Jose Luis; Castillo, Fernando Chinas; Kaltchev, Matey; Tysoe, Wilfred T.

    2006-01-01

    The thermal decomposition of model extreme-pressure lubricant additives on clean iron was studied in ultrahigh vacuum conditions using molecular beam strategies. Methylene chloride and chloroform react to deposit a solid film consisting of FeCl 2 and carbon, and evolve only hydrogen into the gas phase. No gas-phase products and less carbon on the surface are detected in the case of carbon tetrachloride. Dimethyl and diethyl disulfide react on clean iron to deposit a saturated sulfur plus carbon layer at low temperatures (∼600 K) and an iron sulfide film onto a Fe + C underlayer at higher temperatures (∼950 K). Methane is the only gas-phase product when dimethyl disulfide reacts with iron. Ethylene and hydrogen are detected when diethyl disulfide is used

  14. Micro-damage propagation in ultra-high vacuum seals

    CERN Document Server

    Lutkiewicz, P; Garion, C

    2010-01-01

    The paper addresses a fundamental problem of tightness of ultra-high vacuum systems (UHV) at cryogenic temperatures in the light of continuum damage mechanics (CDM). The problem of indentation of a rigid punch into an elastic-plastic half-space is investigated based on rate independent plasticity with mixed kinematic and isotropic hardening. The micro-damage fields are modeled by using an anisotropic approach with a kinetic law of damage evolution suitable for ductile materials and cryogenic temperatures. The model has been experimentally validated and the results are used to predict the onset of macro-cracking (loss of tightness) and the corresponding load (contact pressure). The algorithm is applied in the design of UHV systems for particle accelerators. (C) 2009 Published by Elsevier Ltd.

  15. TFTR ultrahigh-vacuum pumping system incorporating mercury diffusion pumps

    International Nuclear Information System (INIS)

    Sink, D.A.; Sniderman, M.

    1976-06-01

    The TFTR vacuum vessel will have a system of four 61 cm diameter mercury diffusion pumps to provide a base pressure in the 10 -8 to 10 -9 Torr range as well as a low impurity level within the vessel. The system, called the Torus Vacuum Pumping System (TVPS), will be employed with the aid of an occasional 250 0 C bakeout in situ as well as periodic applications of aggressive discharge cleaning. The TVPS is an ultrahigh-vacuum (UHV) system using no elastomers as well as being a closed system with respect to tritium or any tritiated gases. The backing system employing approximately 75 all-metal isolation valves is designed with the features of redundancy and flexibility employed in a variety of ways to meet the fundamental requirements and functions enumerated for the TVPS. Since the design, is one which is a modification of the conceptual design of the TVPS, those features which have changed are discussed. Calculations are presented for the major performance parameters anticipated for the TVPS and include conductances, effective pumping speeds, base pressures, operating parameters, getter pump parameters, and calculations of time constants associated with leak checking. Modifications in the vacuum pumping system for the guard regions on the twelve bellows sections are presented so that it is compatible with the main TVPS. The bellows pumping system consists of a mechanical pump unit, a zirconium aluminum getter pump unit and a residual gas analyzer. The control and management of the TVPS is described with particular attention given to providing both manual and automatic control at a local station and at the TFTR Central Control. Such operations as testing, maintenance, leak checking, startup, bakeout, and various other operations are considered in some detail. Various aspects related to normal pulsing, discharge cleaning, non-tritium operations and tritium operations are also taken into consideration. A cost estimate is presented

  16. Note: reliable and reusable ultrahigh vacuum optical viewports.

    Science.gov (United States)

    Arora, P; Sen Gupta, A

    2012-04-01

    We report a simple technique for the realization of ultrahigh vacuum optical viewports. The technique relies on using specially designed thin copper knife-edges and using a thin layer of Vacseal(®) on tip of the knife-edges between the optical flat and the ConFlat(®) (CF) flange. The design of the windows is such that it gives uniform pressure on the flat without breaking it. The assembled window is a complete unit, which can be mounted directly onto a CF flange of the vacuum chamber. It can be removed and reused without breaking the window seal. The design is reliable as more than a dozen such windows have survived several bake out and cooling cycles and have been leak tested up to 10(-11) Torr l/s level with a commercial Helium leak detector. The advantages of this technique are ease of assembly and leak proof sealing that survives multiple temperature cycling making the windows reliable and reusable. © 2012 American Institute of Physics

  17. O-Ring sealing arrangements for ultra-high vacuum systems

    Science.gov (United States)

    Kim, Chang-Kyo; Flaherty, Robert

    1981-01-01

    An all metal reusable O-ring sealing arrangement for sealing two concentric tubes in an ultra-high vacuum system. An O-ring of a heat recoverable alloy such as Nitinol is concentrically positioned between protruding sealing rings of the concentric tubes. The O-ring is installed between the tubes while in a stressed martensitic state and is made to undergo a thermally induced transformation to an austenitic state. During the transformation the O-ring expands outwardly and contracts inwardly toward a previously sized austenitic configuration, thereby sealing against the protruding sealing rings of the concentric tubes.

  18. New design of a variable-temperature ultrahigh vacuum scanning tunneling microscope

    NARCIS (Netherlands)

    Mugele, Friedrich Gunther; Rettenberger, A.; Boneberg, J.; Leiderer, P.

    1998-01-01

    We present the design of a variable-temperature ultrahigh vacuum (UHV) scanning tunneling microscope which can be operated between 20 and 400 K. The microscope is mounted directly onto the heat exchanger of a He continuous flow cryostat without vibration isolation inside the UHV chamber. The coarse

  19. Baking enables McLeod gauge to measure in ultrahigh vacuum range

    Science.gov (United States)

    Kreisman, W. S.

    1965-01-01

    Accurate measurements in the ultrahigh vacuum range by a conventional McLeod gage requires degassing of the gage's glass walls. A closed system, in which mercury is forced into the gage by gravity alone, and in which the gage components are baked out for long periods, is used to achieve this degassing.

  20. Ultraclean Si/Si interface formation by surface preparation and direct bonding in ultrahigh vacuum

    DEFF Research Database (Denmark)

    Hermansson, Karin; Grey, Francois; Bengtsson, Stefan

    1998-01-01

    Silicon surfaces have been cleaned and bonded in ultrahigh vacuum, at a pressure in the 10(-10) Torr range. The bonded interfaces show extremely low contamination levels as measured by secondary ion mass spectroscopy. Nevertheless, a potential barrier could be detected at the interface by spreading...

  1. A compact combined ultrahigh vacuum scanning tunnelling microscope (UHV STM) and near-field optical microscope

    International Nuclear Information System (INIS)

    Woolley, R A J; Hayton, J A; Cavill, S; Ma, Jin; Beton, P H; Moriarty, P

    2008-01-01

    We have designed and constructed a hybrid scanning near-field optical microscope (SNOM)–scanning tunnelling microscope (STM) instrument which operates under ultrahigh vacuum (UHV) conditions. Indium tin oxide (ITO)-coated fibre-optic tips capable of high quality STM imaging and tunnelling spectroscopy are fabricated using a simple and reliable method which foregoes the electroless plating strategy previously employed by other groups. The fabrication process is reproducible, producing robust tips which may be exchanged under UHV conditions. We show that controlled contact with metal surfaces considerably enhances the STM imaging capabilities of fibre-optic tips. Light collection (from the cleaved back face of the ITO-coated fibre-optic tip) and optical alignment are facilitated by a simple two-lens arrangement where the in-vacuum collimation/collection lens may be adjusted using a slip-stick motor. A second in-air lens focuses the light (which emerges from the UHV system as a parallel beam) onto a cooled CCD spectrograph or photomultiplier tube. The application of the instrument to combined optical and electronic spectroscopy of Au and GaAs surfaces is discussed

  2. The design and structure of the ultra-high vacuum system of HIRFL-CSR

    International Nuclear Information System (INIS)

    Yang Xiaotian; Zhang Junhui; Zhang Xinjun; Meng Jun; Zhan Wenlong

    2001-01-01

    To minimize the beam loss due to charge exchange of very heavy ions with the residual gas molecules, ultra-high vacuum of 6x10 -9 Pa is required for the HIRFL-CSR facility, which is the lowest pressure in a large vacuum system in China up to now. The total length of the system is about 450 meters and the total inner surface is about 263 square meters. More than 500 standard vacuum components are needed and more than 400 different chambers have to be manufactured. A lot of researches have been down to try to find out the experiences to obtain the required pressure. In this article the following contents are described: the layout of the system; the structure of main vacuum chambers; the treatment method to reduce the outgassing rate of the chamber wall surfaces; vacuum equipment; pressure distribution and the progress of the system

  3. Achieving ultrahigh vacuum in an unbaked chamber with glow ...

    Indian Academy of Sciences (India)

    2016-12-06

    Dec 6, 2016 ... An ultimate vacuum in any leak-tight chamber with a given pumping speed and ... chamber is exposed to atmospheric pressure, water vapour gets sorbed ... A variable DC power supply of 0–1000 V was con- nected in series ...

  4. A novel ultra-high vacuum manipulator with six degrees of freedom

    International Nuclear Information System (INIS)

    Auciello, O.; Lulich, C.; Alonso, E.V.; Baragiola, R.A.

    1977-01-01

    An ultra-high vacuum goniometer of novel design for use in experiments with ion beams is described. The goniometer uses a wire system to transmit movements, is bakeable to 200 0 C and is reproducible in its angular positions to within 1.3 X 10 -4 rad (0.008 0 ). It allows a sample to be rotated around two axes over 360 0 , around a third over 180 0 , and to be translated along three perpendicular axes. (Auth.)

  5. Tribological reactions of perfluoroalkyl polyether oils with stainless steel under ultrahigh vacuum conditions at room temperature

    Science.gov (United States)

    Mori, Shigeyuki; Morales, Wilfredo

    1989-01-01

    The reaction between three types of commercial perfluoroalkyl polyether (PFPE) oils and stainless steel 440C was investigated experimentally during sliding under ultrahigh vacuum conditions at room temperature. It is found that the tribological reaction of PFPE is mainly affected by the activity of the mechanically formed fresh surfaces of metals rather than the heat generated at the sliding contacts. The fluorides formed on the wear track act as a boundary layer, reducing the friction coefficient.

  6. Ultra-high vacuum system of the Brookhaven National Synchrotron Light Source

    International Nuclear Information System (INIS)

    Foerster, C.L.

    1995-01-01

    The rings of the National Synchrotron Light Source (NSLS) have been supplying light to numerous users for approximately a decade and recently a fully conditioned machine vacuum at design currents was obtained. A brief description of the x-ray storage ring, the VUV storage ring and their current supply is given along with some of their features. The ultra-high vacuum system employed for the storage rings and their advantages for the necessary stored beam environments are discussed including, a brief history of time. 15 refs., 2 tabs., 8 figs

  7. Differential ultrahigh-vacuum pump for electron microscope

    International Nuclear Information System (INIS)

    Kroshkov, A.A.; Aseev, A.L.; Baranova, E.A.; Latyshev, A.V.; Yakushenko, O.A.

    1985-01-01

    A differential cryogenic pump for the JEM-7A microscope is described. It reduces the vacuum pressure in the region of the specimen. The device allows tilting and movement of the specimen, direct electrical heating, measurement of specimen temperature, and deposition of films of various substances on the specimen surface. A diagram of the pump shows its placement in the objective chamber of the microscope. The fittings are equipped with bellows and provide for input and output of liquid nitrogen or liquid-helium vapor coolants. The enumerated results attest to a reduction of residual atmospheric pressure in the area of the specimen and the possibility of producing a pure silicon surface in the described device

  8. New method for the simultaneous condensation of complete ternary alloy systems under ultrahigh vacuum conditions

    International Nuclear Information System (INIS)

    Mehrtens, A.; Moske, M.; Samwer, K.

    1988-01-01

    An ultrahigh vacuum apparatus is described for the simultaneous condensation of complete ternary alloy systems. Three singly controlled electron beam evaporation sources provide a constant evaporation rate of the different elements. A specially designed rotating mask guarantees a concentration gradient on the substrate according to a ternary phase diagram. The conversion of the actual concentration profile into a standard ternary phase diagram is done by simple computer calculations. They involve corrections for the beam characteristics of the evaporation sources and for the rotating mask. As an example, measurements for the Zr--Cu--Co system are given. The concentration range for the amorphous phase is compared with thermodynamic predictions using Miedema's parameter

  9. Implementation of complex nanosystems using a versatile ultrahigh vacuum nonlithographic technique

    International Nuclear Information System (INIS)

    Das, Biswajit; Banerjee, Arghya

    2007-01-01

    We have developed an ultrahigh vacuum technique for the implementation of complex nanosystems incorporating nonlithographic nanoparticles, ohmic contact metals and isolation dielectrics. The technique is compatible with the silicon integrated circuit manufacturing process and is versatile, allowing the deposition of nanoparticles of any metal, semiconductor or insulator with diameters as small as 2 nm with less than 5% size variation. In addition, the technique allows the creation of multi-layered structures of nanoparticles of different dimensions. The flexibility and the versatility of the technique have been demonstrated by depositing nanoparticles of various materials as well as fabricating multi-layered structures incorporating nanoparticles

  10. Low loss hollow optical-waveguide connection from atmospheric pressure to ultra-high vacuum

    Energy Technology Data Exchange (ETDEWEB)

    Ermolov, A.; Mak, K. F.; Tani, F.; Hölzer, P.; Travers, J. C. [Max Planck Institute for the Science of Light, Günther-Scharowsky-Str. 1, 91058 Erlangen (Germany); Russell, P. St. J. [Max Planck Institute for the Science of Light, Günther-Scharowsky-Str. 1, 91058 Erlangen (Germany); Department of Physics, University of Erlangen-Nuremberg, Günther-Scharowsky-Str. 1, 91058 Erlangen (Germany)

    2013-12-23

    A technique for optically accessing ultra-high vacuum environments, via a photonic-crystal fiber with a long small hollow core, is described. The small core and the long bore enable a pressure ratio of over 10{sup 8} to be maintained between two environments, while permitting efficient and unimpeded delivery of light, including ultrashort optical pulses. This delivery can be either passive or can encompass nonlinear optical processes such as optical pulse compression, deep UV generation, supercontinuum generation, or other useful phenomena.

  11. Structure and chemistry of model catalysts in ultrahigh vacuum

    Science.gov (United States)

    Walker, Joshua D.

    The study of catalysis is a key area of focus not only in the industrial sector but also in the nature and biological systems. The market for catalysis is a multi-billion dollar industry. Many of the materials and products we use on a daily basis are formed through a catalytic process. The quest to understanding and improving catalytic mechanisms is ongoing. Many model catalysts use transition metals as a support for chemical reactions to take place due to their selectivity and activity. Palladium, gold, and copper metals are studied in this work and show the ability to be catalytically reactive. It is important to understand the characteristics and properties of these surfaces. A well-known example of catalysis is the conversion of carbon monoxide (CO), a very harmful gas to carbon dioxide (CO2) which is less harmful. This reaction is mainly seen in the automotive industry. This reaction is investigated in this work on a Au(111) single crystal, which is normally inert but becomes reactivity with the adsorption of oxygen on the surface. Temperature Programmed Desorption (TPD) is used to understand some of the chemistry and effects with and without the addition of H2O. The oxidation of CO is shown to be enhanced by the addition of water, but warrants further analysis too fully understand the different mechanisms and reaction pathways existing. The field of nano-electronics is rapidly growing as technology continues to challenge scientists to create innovative ideas. The trend to produce smaller electronic products is increasing as consumer demands persist. It has been shown previously that 1,4-phenlyene diisocyanobenzene (1,4-PDI) on Au(111) react to form one-dimensional oligomer chains comprising alternating gold and 1,4-PDI units on the Au(111) surface. A similar compound 1,3-phenlyene diisocyanobenzene (1,3-PDI) was studied in order to investigate whether the oligomerization found for 1,4-PDI is a general phenomenon and to ultimately explore the effect of

  12. Ultra-high vacuum compatible optical chopper system for synchrotron x-ray scanning tunneling microscopy

    Energy Technology Data Exchange (ETDEWEB)

    Chang, Hao, E-mail: hc000211@ohio.edu [Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States); Nanoscale and Quantum Phenomena Institute, Physics & Astronomy Department, Ohio University, Athens, Ohio 45701 (United States); Cummings, Marvin; Shirato, Nozomi; Stripe, Benjamin; Preissner, Curt; Freeland, John W. [Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States); Rosenmann, Daniel [Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States); Kersell, Heath; Hla, Saw-Wai [Nanoscale and Quantum Phenomena Institute, Physics & Astronomy Department, Ohio University, Athens, Ohio 45701 (United States); Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States); Rose, Volker, E-mail: vrose@anl.gov [Advanced Photon Source, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States); Center for Nanoscale Materials, Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States)

    2016-01-28

    High-speed beam choppers are a crucial part of time-resolved x-ray studies as well as a necessary component to enable elemental contrast in synchrotron x-ray scanning tunneling microscopy (SX-STM). However, many chopper systems are not capable of operation in vacuum, which restricts their application to x-ray studies with high photon energies, where air absorption does not present a significant problem. To overcome this limitation, we present a fully ultra-high vacuum (UHV) compatible chopper system capable of operating at variable chopping frequencies up to 4 kHz. The lightweight aluminum chopper disk is coated with Ti and Au films to provide the required beam attenuation for soft and hard x-rays with photon energies up to about 12 keV. The chopper is used for lock-in detection of x-ray enhanced signals in SX-STM.

  13. Pressure measurements in the AGS Booster ultra-high vacuum system

    International Nuclear Information System (INIS)

    Gabusi, J.; Geller, J.; Hseuh, H.C.; Mapes, M.; Stattel, P.

    1992-01-01

    An average pressure of mid 10 -11 Torr has been achieved and maintained in the AGS Booster ring vacuum system during its first year of operation. This ultra-high vacuum system is monitored through remote controlled Bayard-Alpert Gauges (BAGs). The characteristics of the pressure measurements with BAGs over the long cable lengths (up to 200 m) and under various accelerator operating conditions will be described. Two types of noise in the pressure readouts have been identified; the electromagnetic interference (EMI) associated with the acceleration cycles of the Booster and the environment noise associated with the temperature of the collector cables. The magnitude of the noise pickup depends on the routing of the collector cables and reaches the equivalent pressure of low 10 -9 Torr

  14. Hydrogen poisoning of the CO oxidation reaction on Pt and Pd under ultrahigh vacuum conditions

    International Nuclear Information System (INIS)

    Strozier, J.A.

    1977-01-01

    The poisoning by hydrogen of the catalyzed oxidation of CO on Pt and Pd under ultrahigh vacuum conditions was investigated. ac pulsing techniques are used in which the pressure of the reactant CO in the reaction chamber is modulated periodically by means of a fast piezoelectric ultrahigh vacuum valve, and the ac component of the product CO 2 is recorded mass spectroscopically by phase-sensitive techniques. The ac CO 2 production rate is measured as a function of hydrogen pressure (1 - 10 x 10 -9 toor) at constant CO and O 2 pressures (approximately equal to 5 x 10 -8 torr), and constant temperature (approximately equal to 700 K). Exact theoretical calculations of CO 2 production rates were carried out employing several models, i.e., oxygen burn-off by hydrogen, incorporating both the Eley-Rideal and Langmuir-Hinshelwood mechanisms. From a comparison with the experimental results, the probable reaction is of the Langmuir-Hinshelwood type and the relevant rate constant is also determined. These results are compared with other results in the literature on hydrogen oxidation on the surface of Pt

  15. Ultra-high vacuum system of the Brookhaven National Synchrotron Light Source

    Energy Technology Data Exchange (ETDEWEB)

    Foerster, C.L.

    1995-12-31

    The rings of the National Synchrotron Light Source (NSLS) have been supplying light to numerous users for approximately a decade and we recently enjoyed a fully conditioned machine vacuum at design currents. A brief description of the X-Ray storage ring, the VUV storage ring and their current supply is given along with some of their features. The ultra-high vacuum system employed for the storage rings and their advantages for the necessary stored beam environments are discussed including, a brief history of time. After several hundred amp hours of stored beam current operation, very little improvement in machine performance was seen due to conditioning. Sections of the rings were vented, to dry nitrogen and replacement components were pre-baked and pre-argon glow conditioned prior to installation. Very little machine conditioning was needed to return to operation after recovering vacuum due to well established conditioning procedures. All straight sections in the X-Ray ring and the VUV ring have been filled with various insertion devices and most are fully operational. Each storage ring has a computer controlled total pressure and partial pressure monitoring system for the ring and its beam ports, to insure good vacuum.

  16. Ultrasensitive leak detection during ultrahigh vacuum evacuation by quadrupole mass spectrometer

    International Nuclear Information System (INIS)

    Chen Xu; Huang Tianbin; Wang Ligong; Jin Qiji; Cha Liangzhen

    2006-01-01

    One must do ultrasensitive leak detection during ultrahigh-vacuum (UHV) evacuation, especially just before the device is sealed off from the vacuum system, to guarantee the longevity of the sealed high-vacuum or even UHV devices with small volume. A quadrupole mass spectrometer (QMS) with an UHV evacuation system can be used under accumulation mode to do the testing. Possible accumulate modes, as well as their advantages and shortcomings, are studied experimentally and discussed in this paper. We found that the opening action of the metal valve during accumulation mode always severely affects the height of the peak indicated by QMS and causes considerable errors. If we determine the leak rate by the peak area instead of the peak height, the situation is much improved. This method has proven quite useful in ensuring the tightness quality for complex sealed UHV devices with small volumes. Ultrasensitive leak detection has been carried out for such real evacuating devices, and a leak rate of 2x10 -14 Pa·m 3 /s was detected, which is far lower than its dynamic mode and the detection limit of the current advanced commercial leak detectors

  17. Magnetic anisotropy in iron thin films evaporated under ultra-high vacuum

    International Nuclear Information System (INIS)

    Dinhut, J.F.; Eymery, J.P.; Krishnan, R.

    1992-01-01

    α-iron thin films with thickness ranging between 20 and 1500 nm have been evaporated using an electron gun under ultra-high vacuum conditions (5.10 -7 P). The columnar structure observed in cross-sectional TEM is related to the large surface diffusion. From Moessbauer spectra the spin orientation is deduced and found to be influenced by the column axis. Spins can be obtained perpendicularly to the film plane by rotating the substrte during the deposition. The magnetization of the samples is reduced by about 30% and the reduction attributed to the interstitial space which increases with the incident angle. The substrate rotation also decreases Ku( parallel ) by a factor 2 and increases Ku( perpendicular to ). (orig.)

  18. An ultrahigh vacuum fast-scanning and variable temperature scanning tunneling microscope for large scale imaging.

    Science.gov (United States)

    Diaconescu, Bogdan; Nenchev, Georgi; de la Figuera, Juan; Pohl, Karsten

    2007-10-01

    We describe the design and performance of a fast-scanning, variable temperature scanning tunneling microscope (STM) operating from 80 to 700 K in ultrahigh vacuum (UHV), which routinely achieves large scale atomically resolved imaging of compact metallic surfaces. An efficient in-vacuum vibration isolation and cryogenic system allows for no external vibration isolation of the UHV chamber. The design of the sample holder and STM head permits imaging of the same nanometer-size area of the sample before and after sample preparation outside the STM base. Refractory metal samples are frequently annealed up to 2000 K and their cooldown time from room temperature to 80 K is 15 min. The vertical resolution of the instrument was found to be about 2 pm at room temperature. The coarse motor design allows both translation and rotation of the scanner tube. The total scanning area is about 8 x 8 microm(2). The sample temperature can be adjusted by a few tens of degrees while scanning over the same sample area.

  19. Use of nuclear method analysis in ultrahigh vacuum. Application to the hydrogen dosage in solids

    International Nuclear Information System (INIS)

    Chartoire, M.

    1982-01-01

    It is possible to determine hydrogen by the 1 H( 15 N,αγ) 12 C nuclear reaction, in an ultra-high vacuum and with sample temperature monitoring, without reducing the detection efficiency of the γ rays emitted. This method is sensitive on the surface of the samples as well as in the core. Further, its resolution in depth on the surface is less than 50 x 10 -4 μm for elements with an atomic number above that of silicon. This surface analysis technique competes with and supplements the performance of the Auger and ESCA spectrometries. The cooling or heating of the samples in-situ from -150 0 C to +450 0 C enables an initial approach to be made to the phenomena of adsorption of the hydrogenated species on the surface of the samples. The possibility of plotting concentration profiles to depths of around a micrometer, also provides a means for studying the sorption of hydrogen in solids. The importance is brought to light of the quality of the residual vacuum and mainly of the partial steam pressure in the curves showing the change in the concentration of surface contamination hydrogen according to the quantity of incident ions. At temperatures above 300 0 C, the radiolysis and desorption phenomena of the species thus created become very significant. These were obtained only by making a study in greater depth of the validity conditions of the model used for describing the effusion of hydrogen under the analytical beam [fr

  20. dc breakdown conditioning and breakdown rate of metals and metallic alloys under ultrahigh vacuum

    Directory of Open Access Journals (Sweden)

    A. Descoeudres

    2009-03-01

    Full Text Available The rf accelerating structures of the Compact Linear Collider (CLIC require a material capable of sustaining high electric field with a low breakdown rate and low induced damage. Because of the similarity of many aspects of dc and rf breakdown, a dc breakdown study is underway at CERN in order to test candidate materials and surface preparations, and have a better understanding of the breakdown mechanism under ultrahigh vacuum in a simple setup. Conditioning speeds and breakdown fields of several metals and alloys have been measured. The average breakdown field after conditioning ranges from 100  MV/m for Al to 850  MV/m for stainless steel, and is around 170  MV/m for Cu which is the present base-line material for CLIC structures. The results indicate clearly that the breakdown field is limited by the cathode. The presence of a thin cuprous oxide film at the surface of copper electrodes significantly increases the breakdown field. On the other hand, the conditioning speed of Mo is improved by removing oxides at the surface with a vacuum heat treatment, typically at 875°C for 2 hours. Surface finishing treatments of Cu samples only affect the very first breakdowns. More generally, surface treatments have an effect on the conditioning process itself, but not on the average breakdown field reached after the conditioning phase. In analogy to rf, the breakdown probability has been measured in dc with Cu and Mo electrodes. The dc data show similar behavior as rf as a function of the applied electric field.

  1. dc breakdown conditioning and breakdown rate of metals and metallic alloys under ultrahigh vacuum

    CERN Document Server

    Descoeudres, A; Calatroni, S; Taborelli, M; Wuensch, W

    2009-01-01

    RF accelerating structures of the Compact Linear Collider (CLIC) require a material capable of sustaining high electric field with a low breakdown rate and low induced damage. Because of the similarity of many aspects of DC and RF breakdown, a DC breakdown study is underway at CERN in order to test candidate materials and surface preparations, and have a better understanding of the breakdown mechanism under ultra-high vacuum in a simple setup. Conditioning speeds and breakdown fields of several metals and alloys have been measured. The average breakdown field after conditioning ranges from 100 MV/m for Al to 850 MV/m for stainless steel, and is around 170 MV/m for Cu which is the present base-line material for CLIC structures. The results indicate clearly that the breakdown field is limited by the cathode. The presence of a thin cuprous oxide film at the surface of copper electrodes significantly increases the breakdown field. On the other hand, the conditioning speed of Mo is improved by removing oxides at t...

  2. Controlled planar interface synthesis by ultrahigh vacuum diffusion bonding/deposition

    International Nuclear Information System (INIS)

    Kim, M. J.; Carpenter, R. W.; Cox, M. J.; Xu, J.

    2000-01-01

    An ultrahigh vacuum (UHV) diffusion bonding/deposition instrument was designed and constructed, which can produce homophase and heterophase planar interfaces from a wide array of materials. The interfaces are synthesized in situ by diffusion bonding of two substrates with or without various interfacial layers, at temperatures up to about 1500 degree sign C. Substrate surfaces can be heat treated, ion-beam sputter cleaned, and chemically characterized in situ by Auger electron spectroscopy prior to deposition and/or bonding. Bicrystals can be synthesized by bonding two single-crystal substrates at a specified orientation. Interfacial layers can be deposited by electron beam evaporation and/or sputter deposition in any layered or alloyed combination on the substrates before bonding. The instrument can accommodate cylindrical and/or wafer type specimens whose sizes are sufficient for fracture mechanical testing to measure interface bond strength. A variety of planar interfaces of metals, semiconductors, and ceramics were synthesized. Examples of bonded stainless steel/Ti/stainless steel, Si/Si, and sapphire/sapphire interfaces are presented. (c) 2000 Materials Research Society

  3. Ultra-high vacuum target assembly for charged particle irradiations in the materials research field

    International Nuclear Information System (INIS)

    Bressers, J.; Cassanelli, G.; Cat, R. de; Kohnen, H.; Gherardi, G.

    1978-01-01

    A target assembly designed for ion irradiation and ion implantation experiments on different particle accelerators is described. It consists of a target chamber separated from the beam line by a thin metal window, thus allowing implantations to be carried out under ultra-high vacuum conditions. Homogeneous in-depth distribution of the implanted ion species is realized by rotating the target about an axis perpendicular to the ion beam (rocking). The target holder is driven by means of a stepping motor with a constant step angle and a rocking device controller containing the required rocking angle-dwell time relation. Ion beam homogeneity over a sufficiently large target area is arrived at by transforming the Gaussian beam intensity profile into a flat beam intensity distribution by means of an electrostatic ring lens. The beam intensity profile is monitored by means of a specially designed ion beam monitor based on the Nipkov disc principle. A toroidal beam current monitoring transformer continuously measures the total beam current. Beam scanners and current measuring collimators complete the beam analysing equipment

  4. Atmospheric pressure reaction cell for operando sum frequency generation spectroscopy of ultrahigh vacuum grown model catalysts

    Science.gov (United States)

    Roiaz, Matteo; Pramhaas, Verena; Li, Xia; Rameshan, Christoph; Rupprechter, Günther

    2018-04-01

    A new custom-designed ultrahigh vacuum (UHV) chamber coupled to a UHV and atmospheric-pressure-compatible spectroscopic and catalytic reaction cell is described, which allows us to perform IR-vis sum frequency generation (SFG) vibrational spectroscopy during catalytic (kinetic) measurements. SFG spectroscopy is an exceptional tool to study vibrational properties of surface adsorbates under operando conditions, close to those of technical catalysis. This versatile setup allows performing surface science, SFG spectroscopy, catalysis, and electrochemical investigations on model systems, including single crystals, thin films, and deposited metal nanoparticles, under well-controlled conditions of gas composition, pressure, temperature, and potential. The UHV chamber enables us to prepare the model catalysts and to analyze their surface structure and composition by low energy electron diffraction and Auger electron spectroscopy, respectively. Thereafter, a sample transfer mechanism moves samples under UHV to the spectroscopic cell, avoiding air exposure. In the catalytic cell, SFG spectroscopy and catalytic tests (reactant/product analysis by mass spectrometry or gas chromatography) are performed simultaneously. A dedicated sample manipulation stage allows the model catalysts to be examined from LN2 temperature to 1273 K, with gaseous reactants in a pressure range from UHV to atmospheric. For post-reaction analysis, the SFG cell is rapidly evacuated and samples are transferred back to the UHV chamber. The capabilities of this new setup are demonstrated by benchmark results of CO adsorption on Pt and Pd(111) single crystal surfaces and of CO adsorption and oxidation on a ZrO2 supported Pt nanoparticle model catalyst grown by atomic layer deposition.

  5. The use of non-destructive testing in COSY, an ultrahigh vacuum research plant of KFA, Juelich

    International Nuclear Information System (INIS)

    Schroeder, G.; Pauly, F.; Stechemesser, H.

    1993-01-01

    This report shows that the development, the construction and the later successful operation of ultra-high vacuum (UHV) plants in the pressure range of ≤ 10 -10 mbar is not possible without the use of highly sensitive non-destructive testing. Using the example of the large scale precision plant COSY, it is shown that only by observing basic UHV manufacturing conditions and the thorough use of the helium leak-finding technique and mass-spectrometric residual gas analysis can the required leakage rates ( -10 mbar. 1 . s -1 ) and surface cleanliness be achieved. (orig.) [de

  6. Electrospray deposition of fullerenes in ultra-high vacuum: in situ scanning tunneling microscopy and photoemission spectroscopy

    International Nuclear Information System (INIS)

    Satterley, Christopher J; Perdigao, LuIs M A; Saywell, Alex; Magnano, Graziano; Rienzo, Anna; Mayor, Louise C; Dhanak, Vinod R; Beton, Peter H; O'Shea, James N

    2007-01-01

    Electrospray deposition of fullerenes on gold has been successfully observed by in situ room temperature scanning tunneling microscopy and photoemission spectroscopy. Step-edge decoration and hexagonal close-packed islands with a periodicity of 1 nm are observed at low and multilayer coverages respectively, in agreement with thermal evaporation studies. Photoemission spectroscopy shows that fullerenes are being deposited in high purity and are coupling to the gold surface as for thermal evaporation. These results open a new route for the deposition of thermally labile molecules under ultra-high vacuum conditions for a range of high resolution surface science techniques

  7. Ultrahigh-vacuum in situ electrochemistry with solid polymer electrolyte and x-ray photoelectron spectroscopy studies of polypyrrole

    International Nuclear Information System (INIS)

    Skotheim, T.A.; Florit, M.I.; Melo, A.; O'Grady, W.E.

    1984-01-01

    A new in situ combined electrochemistry and x-ray-photoelectron-spectroscopy (XPS) technique using solid polymer electrolytes has been used to characterize electrically conducting films of polypyrrole perchlorate. The technique allows in situ electrochemical oxidation and reduction (doping and undoping) in ultrahigh vacuum and the simultaneous study of the polymer with XPS as a function of its electrochemical potential. We demonstrate that some anion species interact strongly electrostatically with the nitrogen heteroatoms. We also show conclusively that the electrochemistry of polypyrrole is highly irreversible

  8. An atomic resolution scanning tunneling microscope that applies external tensile stress and strain in an ultrahigh vacuum

    International Nuclear Information System (INIS)

    Fujita, D; Kitahara, M; Onishi, K; Sagisaka, K

    2008-01-01

    We have developed an ultrahigh vacuum scanning tunneling microscope with an in situ external stress application capability in order to determine the effects of stress and strain on surface atomistic structures. It is necessary to understand these effects because controlling them will be a key technology that will very likely be used in future nanometer-scale fabrication processes. We used our microscope to demonstrate atomic resolution imaging under external tensile stress and strain on the surfaces of wafers of Si(111) and Si(001). We also successfully observed domain redistribution induced by applying uniaxial stress at an elevated temperature on the surface of a wafer of vicinal Si(100). We confirmed that domains for which an applied tensile stress is directed along the dimer bond become less stable and shrink. This suggests that it may be feasible to fabricate single domain surfaces in a process that controls surface stress and strain

  9. Tetrasilane and digermane for the ultra-high vacuum chemical vapor deposition of SiGe alloys

    International Nuclear Information System (INIS)

    Hart, John; Hazbun, Ramsey; Eldridge, David; Hickey, Ryan; Fernando, Nalin; Adam, Thomas; Zollner, Stefan; Kolodzey, James

    2016-01-01

    Tetrasilane and digermane were used to grow epitaxial silicon germanium layers on silicon substrates in a commercial ultra-high vacuum chemical vapor deposition tool. Films with concentrations up to 19% germanium were grown at temperatures from 400 °C to 550 °C. For all alloy compositions, the growth rates were much higher compared to using mono-silane and mono-germane. The quality of the material was assessed using X-ray diffraction, atomic force microscopy, and spectroscopic ellipsometry; all indicating high quality epitaxial films with low surface roughness suitable for commercial applications. Studies of the decomposition kinetics with regard to temperature were performed, revealing an unusual growth rate maximum between the high and low temperature deposition regimes. - Highlights: • Higher order precursors tetrasilane and digermane • Low temperature deposition • Thorough film characterization with temperature • Arrhenius growth rate peak

  10. Multifunctional ultra-high vacuum apparatus for studies of the interactions of chemical warfare agents on complex surfaces

    International Nuclear Information System (INIS)

    Wilmsmeyer, Amanda R.; Morris, John R.; Gordon, Wesley O.; Mantooth, Brent A.; Lalain, Teri A.; Davis, Erin Durke

    2014-01-01

    A fundamental understanding of the surface chemistry of chemical warfare agents is needed to fully predict the interaction of these toxic molecules with militarily relevant materials, catalysts, and environmental surfaces. For example, rules for predicting the surface chemistry of agents can be applied to the creation of next generation decontaminants, reactive coatings, and protective materials for the warfighter. Here, we describe a multifunctional ultra-high vacuum instrument for conducting comprehensive studies of the adsorption, desorption, and surface chemistry of chemical warfare agents on model and militarily relevant surfaces. The system applies reflection-absorption infrared spectroscopy, x-ray photoelectron spectroscopy, and mass spectrometry to study adsorption and surface reactions of chemical warfare agents. Several novel components have been developed to address the unique safety and sample exposure challenges that accompany the research of these toxic, often very low vapor pressure, compounds. While results of vacuum-based surface science techniques may not necessarily translate directly to environmental processes, learning about the fundamental chemistry will begin to inform scientists about the critical aspects that impact real-world applications

  11. Multifunctional ultra-high vacuum apparatus for studies of the interactions of chemical warfare agents on complex surfaces.

    Science.gov (United States)

    Wilmsmeyer, Amanda R; Gordon, Wesley O; Davis, Erin Durke; Mantooth, Brent A; Lalain, Teri A; Morris, John R

    2014-01-01

    A fundamental understanding of the surface chemistry of chemical warfare agents is needed to fully predict the interaction of these toxic molecules with militarily relevant materials, catalysts, and environmental surfaces. For example, rules for predicting the surface chemistry of agents can be applied to the creation of next generation decontaminants, reactive coatings, and protective materials for the warfighter. Here, we describe a multifunctional ultra-high vacuum instrument for conducting comprehensive studies of the adsorption, desorption, and surface chemistry of chemical warfare agents on model and militarily relevant surfaces. The system applies reflection-absorption infrared spectroscopy, x-ray photoelectron spectroscopy, and mass spectrometry to study adsorption and surface reactions of chemical warfare agents. Several novel components have been developed to address the unique safety and sample exposure challenges that accompany the research of these toxic, often very low vapor pressure, compounds. While results of vacuum-based surface science techniques may not necessarily translate directly to environmental processes, learning about the fundamental chemistry will begin to inform scientists about the critical aspects that impact real-world applications.

  12. Multifunctional ultra-high vacuum apparatus for studies of the interactions of chemical warfare agents on complex surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Wilmsmeyer, Amanda R.; Morris, John R. [Department of Chemistry, Virginia Tech, Blacksburg, Virginia 24061 (United States); Gordon, Wesley O.; Mantooth, Brent A.; Lalain, Teri A. [Research and Technology Directorate, U.S. Army Edgewood Chemical Biological Center, Aberdeen Proving Ground, Maryland 21010 (United States); Davis, Erin Durke [OptiMetrics, Inc., Abingdon, Maryland 21009 (United States)

    2014-01-15

    A fundamental understanding of the surface chemistry of chemical warfare agents is needed to fully predict the interaction of these toxic molecules with militarily relevant materials, catalysts, and environmental surfaces. For example, rules for predicting the surface chemistry of agents can be applied to the creation of next generation decontaminants, reactive coatings, and protective materials for the warfighter. Here, we describe a multifunctional ultra-high vacuum instrument for conducting comprehensive studies of the adsorption, desorption, and surface chemistry of chemical warfare agents on model and militarily relevant surfaces. The system applies reflection-absorption infrared spectroscopy, x-ray photoelectron spectroscopy, and mass spectrometry to study adsorption and surface reactions of chemical warfare agents. Several novel components have been developed to address the unique safety and sample exposure challenges that accompany the research of these toxic, often very low vapor pressure, compounds. While results of vacuum-based surface science techniques may not necessarily translate directly to environmental processes, learning about the fundamental chemistry will begin to inform scientists about the critical aspects that impact real-world applications.

  13. Ultrahigh vacuum system of the heavy ion transport line at Brookhaven

    International Nuclear Information System (INIS)

    Hseuh, H.C.; Feigenbaum, I.; Manni, M.; Stattel, P.; Skelton, R.

    1985-01-01

    Heavy ions with an energy up to 8 MeV/A for S +16 and 1 MeV/A for Au +34 from the 16 MV Tandem will be injected into the AGS for further acceleration to less than or equal to 15 GeV/A. A 600-meter beam transport line between the Tandem and the AGS has been designed and is under construction. This paper describes the design of the vacuum system of this transport line and the performance of the prototype vacuum sectors

  14. Additive manufacturing of magnetic shielding and ultra-high vacuum flange for cold atom sensors.

    Science.gov (United States)

    Vovrosh, Jamie; Voulazeris, Georgios; Petrov, Plamen G; Zou, Ji; Gaber, Youssef; Benn, Laura; Woolger, David; Attallah, Moataz M; Boyer, Vincent; Bongs, Kai; Holynski, Michael

    2018-01-31

    Recent advances in the understanding and control of quantum technologies, such as those based on cold atoms, have resulted in devices with extraordinary metrological performance. To realise this potential outside of a lab environment the size, weight and power consumption need to be reduced. Here we demonstrate the use of laser powder bed fusion, an additive manufacturing technique, as a production technique relevant to the manufacture of quantum sensors. As a demonstration we have constructed two key components using additive manufacturing, namely magnetic shielding and vacuum chambers. The initial prototypes for magnetic shields show shielding factors within a factor of 3 of conventional approaches. The vacuum demonstrator device shows that 3D-printed titanium structures are suitable for use as vacuum chambers, with the test system reaching base pressures of 5 ± 0.5 × 10 -10 mbar. These demonstrations show considerable promise for the use of additive manufacturing for cold atom based quantum technologies, in future enabling improved integrated structures, allowing for the reduction in size, weight and assembly complexity.

  15. Vacuum Bloch-Siegert shift in Landau polaritons with ultra-high cooperativity

    Science.gov (United States)

    Li, Xinwei; Bamba, Motoaki; Zhang, Qi; Fallahi, Saeed; Gardner, Geoff C.; Gao, Weilu; Lou, Minhan; Yoshioka, Katsumasa; Manfra, Michael J.; Kono, Junichiro

    2018-06-01

    A two-level system resonantly interacting with an a.c. magnetic or electric field constitutes the physical basis of diverse phenomena and technologies. However, Schrödinger's equation for this seemingly simple system can be solved exactly only under the rotating-wave approximation, which neglects the counter-rotating field component. When the a.c. field is sufficiently strong, this approximation fails, leading to a resonance-frequency shift known as the Bloch-Siegert shift. Here, we report the vacuum Bloch-Siegert shift, which is induced by the ultra-strong coupling of matter with the counter-rotating component of the vacuum fluctuation field in a cavity. Specifically, an ultra-high-mobility two-dimensional electron gas inside a high-Q terahertz cavity in a quantizing magnetic field revealed ultra-narrow Landau polaritons, which exhibited a vacuum Bloch-Siegert shift up to 40 GHz. This shift, clearly distinguishable from the photon-field self-interaction effect, represents a unique manifestation of a strong-field phenomenon without a strong field.

  16. Portable ultrahigh-vacuum sample storage system for polarization-dependent total-reflection fluorescence x-ray absorption fine structure spectroscopy

    Energy Technology Data Exchange (ETDEWEB)

    Watanabe, Yoshihide, E-mail: e0827@mosk.tytlabs.co.jp; Nishimura, Yusaku F.; Suzuki, Ryo; Beniya, Atsushi; Isomura, Noritake [Toyota Central R& D Labs., Inc., Yokomichi 41-1, Nagakute, Aichi 480-1192 (Japan); Uehara, Hiromitsu; Asakura, Kiyotaka; Takakusagi, Satoru [Catalysis Research Center, Hokkaido University, Kita 21-10, Sapporo, Hokkaido 001-0021 (Japan); Nimura, Tomoyuki [AVC Co., Ltd., Inada 1450-6, Hitachinaka, Ibaraki 312-0061 (Japan)

    2016-03-15

    A portable ultrahigh-vacuum sample storage system was designed and built to investigate the detailed geometric structures of mass-selected metal clusters on oxide substrates by polarization-dependent total-reflection fluorescence x-ray absorption fine structure spectroscopy (PTRF-XAFS). This ultrahigh-vacuum (UHV) sample storage system provides the handover of samples between two different sample manipulating systems. The sample storage system is adaptable for public transportation, facilitating experiments using air-sensitive samples in synchrotron radiation or other quantum beam facilities. The samples were transferred by the developed portable UHV transfer system via a public transportation at a distance over 400 km. The performance of the transfer system was demonstrated by a successful PTRF-XAFS study of Pt{sub 4} clusters deposited on a TiO{sub 2}(110) surface.

  17. Refined tip preparation by electrochemical etching and ultrahigh vacuum treatment to obtain atomically sharp tips for scanning tunneling microscope and atomic force microscope.

    Science.gov (United States)

    Hagedorn, Till; El Ouali, Mehdi; Paul, William; Oliver, David; Miyahara, Yoichi; Grütter, Peter

    2011-11-01

    A modification of the common electrochemical etching setup is presented. The described method reproducibly yields sharp tungsten tips for usage in the scanning tunneling microscope and tuning fork atomic force microscope. In situ treatment under ultrahigh vacuum (p ≤10(-10) mbar) conditions for cleaning and fine sharpening with minimal blunting is described. The structure of the microscopic apex of these tips is atomically resolved with field ion microscopy and cross checked with field emission. © 2011 American Institute of Physics

  18. Refined tip preparation by electrochemical etching and ultrahigh vacuum treatment to obtain atomically sharp tips for scanning tunneling microscope and atomic force microscope

    International Nuclear Information System (INIS)

    Hagedorn, Till; Ouali, Mehdi El; Paul, William; Oliver, David; Miyahara, Yoichi; Gruetter, Peter

    2011-01-01

    A modification of the common electrochemical etching setup is presented. The described method reproducibly yields sharp tungsten tips for usage in the scanning tunneling microscope and tuning fork atomic force microscope. In situ treatment under ultrahigh vacuum (p ≤10 -10 mbar) conditions for cleaning and fine sharpening with minimal blunting is described. The structure of the microscopic apex of these tips is atomically resolved with field ion microscopy and cross checked with field emission.

  19. Conceptual design and application studies of piezoelectric crystal motors under ultra-high vacuum conditions

    International Nuclear Information System (INIS)

    Nagler, Jens

    2009-08-01

    For the operation of accelerators it is important that motions in the vacuum occur. The here produced diploma thesis deals with the possibility to perform thes motions with piezocrystal motors in order to abandon wear-susceptible membrane bellows. For this studies have been performed, which should show for which it is useful to apply a piezocrystal motor. Limits are shown, advances and disadvantages are weighted in the thesis. Construction with with subsequent test of a tandem facility and an outlook on possible future concepts form the main content [de

  20. Sample mounting and transfer for coupling an ultrahigh vacuum variable temperature beetle scanning tunneling microscope with conventional surface probes

    International Nuclear Information System (INIS)

    Nafisi, Kourosh; Ranau, Werner; Hemminger, John C.

    2001-01-01

    We present a new ultrahigh vacuum (UHV) chamber for surface analysis and microscopy at controlled, variable temperatures. The new instrument allows surface analysis with Auger electron spectroscopy, low energy electron diffraction, quadrupole mass spectrometer, argon ion sputtering gun, and a variable temperature scanning tunneling microscope (VT-STM). In this system, we introduce a novel procedure for transferring a sample off a conventional UHV manipulator and onto a scanning tunneling microscope in the conventional ''beetle'' geometry, without disconnecting the heating or thermocouple wires. The microscope, a modified version of the Besocke beetle microscope, is mounted on a 2.75 in. outer diameter UHV flange and is directly attached to the base of the chamber. The sample is attached to a tripod sample holder that is held by the main manipulator. Under UHV conditions the tripod sample holder can be removed from the main manipulator and placed onto the STM. The VT-STM has the capability of acquiring images between the temperature range of 180--500 K. The performance of the chamber is demonstrated here by producing an ordered array of island vacancy defects on a Pt(111) surface and obtaining STM images of these defects

  1. Heteroepitaxial Growth of Germanium-on-Silicon Using Ultrahigh-Vacuum Chemical Vapor Deposition with RF Plasma Enhancement

    Science.gov (United States)

    Alharthi, Bader; Grant, Joshua M.; Dou, Wei; Grant, Perry C.; Mosleh, Aboozar; Du, Wei; Mortazavi, Mansour; Li, Baohua; Naseem, Hameed; Yu, Shui-Qing

    2018-05-01

    Germanium (Ge) films have been grown on silicon (Si) substrate by ultrahigh-vacuum chemical vapor deposition with plasma enhancement (PE). Argon plasma was generated using high-power radiofrequency (50 W) to assist in germane decomposition at low temperature. The growth temperature was varied in the low range of 250°C to 450°C to make this growth process compatible with complementary metal-oxide-semiconductor technology. The material and optical properties of the grown Ge films were investigated. The material quality was determined by Raman and x-ray diffraction techniques, revealing growth of crystalline films in the temperature range of 350°C to 450°C. Photoluminescence spectra revealed improved optical quality at growth temperatures of 400°C and 450°C. Furthermore, material quality study using transmission electron microscopy revealed existence of defects in the Ge layer grown at 400°C. Based on the etch pit density, the average threading dislocation density in the Ge layer obtained at this growth temperature was measured to be 4.5 × 108 cm-2. This result was achieved without any material improvement steps such as use of graded buffer or thermal annealing. Comparison between PE and non-plasma-enhanced growth, in the same machine at otherwise the same growth conditions, indicated increased growth rate and improved material and optical qualities for PE growth.

  2. An ultrahigh vacuum, low-energy ion-assisted deposition system for III-V semiconductor film growth

    Science.gov (United States)

    Rohde, S.; Barnett, S. A.; Choi, C.-H.

    1989-06-01

    A novel ion-assisted deposition system is described in which the substrate and growing film can be bombarded with high current densities (greater than 1 mA/sq cm) of very low energy (10-200 eV) ions. The system design philosophy is similar to that used in III-V semiconductor molecular-beam epitaxy systems: the chamber is an all-metal ultrahigh vacuum system with liquid-nitrogen-cooled shrouds, Knudsen-cell evaporation sources, a sample insertion load-lock, and a 30-kV reflection high-energy electron diffraction system. III-V semiconductor film growth is achieved using evaporated group-V fluxes and group-III elemental fluxes sputtered from high-purity targets using ions extracted from a triode glow discharge. Using an In target and an As effusion cell, InAs deposition rates R of 2 microns/h have been obtained. Epitaxial growth of InAs was observed on both GaSb(100) and Si(100) substrates.

  3. CHICSi - a compact ultra-high vacuum compatible detector system for nuclear reaction experiments at storage rings. II. Detectors

    Energy Technology Data Exchange (ETDEWEB)

    Golubev, P.; Avdeichikov, V.; Carlen, L.; Jakobsson, B. E-mail: bo.jakobsson@kosufy.lu.se; Siwek, A.; Veldhuizen, E.J. van; Westerberg, L.; Whitlow, H.J

    2003-03-11

    We describe the detectors for identification of charged particles and fragments in CHICSi, a large solid angle multi-telescope system mounted inside an ultra-high vacuum (UHV), cluster-jet target chamber. CHICSi performs nuclear reaction experiments at storage rings. The telescopes consist of a first very thin, 10-14 {mu}m Si detector, a second 300 {mu}m (or possibly 500 {mu}m) ion implanted Si detector supplemented by a 6 mm GSO(Ce) scintillator read out by a photodiode (PD) or by a third 300 {mu}m Si detector. The telescopes provide full charge separation up to Z=17 and mass resolution up to A=9 in the energy range 0.7-60A MeV. The thin p-i-n diode detector, etched out from a 280 {mu}m Si wafer, and the GSO/PD detector, both exclusively developed for CHICSi, provide an energy resolution {<=}8%, while the standard 300 {mu}m detectors have {<=}2% energy resolution. Radiation stability of the Si detectors is confirmed up to an integrated flux of 10{sup 10} alpha particles. The GSO detector has 70% light collection efficiency with the optical coupling to the PD a simple open, 0.2 mm, gap. A new method, developed to perform absolute energy calibration for the GSO/PD detector is presented.

  4. CHICSi - a compact ultra-high vacuum compatible detector system for nuclear reaction experiments at storage rings. II. Detectors

    International Nuclear Information System (INIS)

    Golubev, P.; Avdeichikov, V.; Carlen, L.; Jakobsson, B.; Siwek, A.; Veldhuizen, E.J. van; Westerberg, L.; Whitlow, H.J.

    2003-01-01

    We describe the detectors for identification of charged particles and fragments in CHICSi, a large solid angle multi-telescope system mounted inside an ultra-high vacuum (UHV), cluster-jet target chamber. CHICSi performs nuclear reaction experiments at storage rings. The telescopes consist of a first very thin, 10-14 μm Si detector, a second 300 μm (or possibly 500 μm) ion implanted Si detector supplemented by a 6 mm GSO(Ce) scintillator read out by a photodiode (PD) or by a third 300 μm Si detector. The telescopes provide full charge separation up to Z=17 and mass resolution up to A=9 in the energy range 0.7-60A MeV. The thin p-i-n diode detector, etched out from a 280 μm Si wafer, and the GSO/PD detector, both exclusively developed for CHICSi, provide an energy resolution ≤8%, while the standard 300 μm detectors have ≤2% energy resolution. Radiation stability of the Si detectors is confirmed up to an integrated flux of 10 10 alpha particles. The GSO detector has 70% light collection efficiency with the optical coupling to the PD a simple open, 0.2 mm, gap. A new method, developed to perform absolute energy calibration for the GSO/PD detector is presented

  5. The SSRL ultrahigh vacuum grazing incidence monochromator: design considerations and operating experience

    International Nuclear Information System (INIS)

    Brown, F.C.; Bachrach, R.Z.; Lien, N.

    1978-01-01

    Considerable experience has now accumulated with the 'grasshopper' monochromator installed on the four degree line at the Stanford Synchrotron Radiation Laboratory. This is one of the first bakeable high vacuum instruments for use with a storage ring source in the photon energy range 25 to 1000 eV. The unique features of this instrument will be discussed from a general point of view, including the source emittance and the transforming properties of the beam line plus monochromator. Actual performance figures will be given in order to better appraise the limits of focusing optics and gratings at two degree grazing incidence. Improvements such as post-monochromator optics, isolation valves and provisions for adjustment will be briefly discussed. (Auth.)

  6. Ultra-High Speed Visualization of the Flashing Instability in Micron Size Nozzles under Vacuum Conditions

    KAUST Repository

    Alghamdi, Tariq A.

    2017-11-01

    I visualized the flash-boiling atomization of liquid jets released into a low pressure environment at frame rates of up to five million frames per second. Such a high temporal resolution allowed us to observe for the first time the bubble expansion mechanism that atomizes the jet. To visualize the dynamics in detail, I focused closely to the outflow of the nozzle using a long distance microscope objective. I documented an abrupt transition from a laminar to a fully external flashing jet by systematically reducing the ambient pressure. I performed experiments with different volatile liquids and using nozzles with different inner diameters. The inner diameters of the nozzles varied from 30 to 480 . Perfluorohexane (PFnH) was our main working fluid, but also methanol, ethanol and 1-bromopropane were tested. Surprisingly, minimum intensity profiles revealed spray angles close to ~360°, meaning drops are ejected in all directions. Also, I measured speeds of bubble expansion up to 140 m/s. That is 45 times faster than the upper bound for inertial growth speed in complete vacuum from the Rayleigh-Plesset equation. I also calculated the trajectories of the ejected droplets as well as the drop speed distribution using particle tracking. I expect that our results bring new insight into the flash-boiling atomization mechanism.

  7. Degradation and crosslinking of perfluoroalkyl polyethers under X-ray irradiation in ultrahigh vacuum

    International Nuclear Information System (INIS)

    Mori, S.; Morales, W.

    1989-03-01

    Degradation of three types of commercially available perfluoroalkyl polyethers (PFPE)-Demnum S200, Fomblin Z25, and Krytox 16256-by X-ray irradiation was studied by using X-ray photoemission spectroscopy (XPS) and a mass spectrometer under ultra-high-vacuum conditions. The carbons in the polymers were characterized by chemical shifts of Cls binding energies. Gaseous products containing COF2 and low-molecular-weight fluorocarbons were formed. From Fomblin Z25, which has acetal linkages (-OCF2O-), a large quantity of COF2 gas was evolved. Liquid products became tacky after a long irradiation time, and some did not dissolve in Freon. High-pressure liquid chromatography (HPLC) showed that molecular weight distribution became broader and that higher molecular weight polymers were formed from Demnum and Krytox. We concluded from these results that degradation and cross-linking took place simultaneously. Demnum crosslinked more easily than the other fluids. The time dependence of both XPS spectra of Cls and mass spectra showed that C-O-bonded carbons in PFPE'S were removed faster than other carbons. There was no substrate effect on the degradation reaction because the first-order rate constants calculated from the change of gaseous products were similar when stainless steel (440C) and gold-coated surfaces were used. Metal fluorides were formed on stainless steel during the reaction. A mechanism for the degradation of PFPE'S is discussed on the basis of their molecular structures

  8. Strength of Al and Al-Mg/alumina bonds prepared using ultrahigh vacuum diffusion bonding

    International Nuclear Information System (INIS)

    King, W.E.; Campbell, G.H.; Wien, W.L.; Stoner, S.L.

    1994-01-01

    The authors have measured the cross-breaking strength of Al and Al-Mg alloys bonded with alumina. Diffusion bonding of Al and Al-Mg alloys requires significantly more bonding time than previously thought to obtain complete bonding. In contrast to previous diffusion bonding studies, fracture morphologies are similar to those obtained in bonds formed by liquid phase reaction; i.e., bonds are as strong or stronger than the ceramic; and fracture tends to propagate in the metal for pure Al and near the interface in the ceramic for the alloys. There are indications that the fracture morphology depends on Mg content and therefore on plasticity in the metal

  9. A compact sub-Kelvin ultrahigh vacuum scanning tunneling microscope with high energy resolution and high stability.

    Science.gov (United States)

    Zhang, L; Miyamachi, T; Tomanić, T; Dehm, R; Wulfhekel, W

    2011-10-01

    We designed a scanning tunneling microscope working at sub-Kelvin temperatures in ultrahigh vacuum (UHV) in order to study the magnetic properties on the nanoscale. An entirely homebuilt three-stage cryostat is used to cool down the microscope head. The first stage is cooled with liquid nitrogen, the second stage with liquid (4)He. The third stage uses a closed-cycle Joule-Thomson refrigerator of a cooling power of 1 mW. A base temperature of 930 mK at the microscope head was achieved using expansion of (4)He, which can be reduced to ≈400 mK when using (3)He. The cryostat has a low liquid helium consumption of only 38 ml/h and standing times of up to 280 h. The fast cooling down of the samples (3 h) guarantees high sample throughput. Test experiments with a superconducting tip show a high energy resolution of 0.3 meV when performing scanning tunneling spectroscopy. The vertical stability of the tunnel junction is well below 1 pm (peak to peak) and the electric noise floor of tunneling current is about 6fA/√Hz. Atomic resolution with a tunneling current of 1 pA and 1 mV was achieved on Au(111). The lateral drift of the microscope at stable temperature is below 20 pm/h. A superconducting spilt-coil magnet allows to apply an out-of-plane magnetic field of up to 3 T at the sample surface. The flux vortices of a Nb(110) sample were clearly resolved in a map of differential conductance at 1.1 K and a magnetic field of 0.21 T. The setup is designed for in situ preparation of tip and samples under UHV condition.

  10. Integrating atomic layer deposition and ultra-high vacuum physical vapor deposition for in situ fabrication of tunnel junctions

    Energy Technology Data Exchange (ETDEWEB)

    Elliot, Alan J., E-mail: alane@ku.edu, E-mail: jwu@ku.edu; Malek, Gary A.; Lu, Rongtao; Han, Siyuan; Wu, Judy Z., E-mail: alane@ku.edu, E-mail: jwu@ku.edu [Department of Physics and Astronomy, The University of Kansas, Lawrence, Kansas 66045 (United States); Yu, Haifeng; Zhao, Shiping [Beijing National Laboratory for Condensed Matter Physics, Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2014-07-15

    Atomic Layer Deposition (ALD) is a promising technique for growing ultrathin, pristine dielectrics on metal substrates, which is essential to many electronic devices. Tunnel junctions are an excellent example which require a leak-free, ultrathin dielectric tunnel barrier of typical thickness around 1 nm between two metal electrodes. A challenge in the development of ultrathin dielectric tunnel barriers using ALD is controlling the nucleation of dielectrics on metals with minimal formation of native oxides at the metal surface for high-quality interfaces between the tunnel barrier and metal electrodes. This poses a critical need for integrating ALD with ultra-high vacuum (UHV) physical vapor deposition. In order to address these challenges, a viscous-flow ALD chamber was designed and interfaced to an UHV magnetron sputtering chamber via a load lock. A sample transportation system was implemented for in situ sample transfer between the ALD, load lock, and sputtering chambers. Using this integrated ALD-UHV sputtering system, superconductor-insulator-superconductor (SIS) Nb-Al/Al{sub 2}O{sub 2}/Nb Josephson tunnel junctions were fabricated with tunnel barriers of thickness varied from sub-nm to ∼1 nm. The suitability of using an Al wetting layer for initiation of the ALD Al{sub 2}O{sub 3} tunnel barrier was investigated with ellipsometry, atomic force microscopy, and electrical transport measurements. With optimized processing conditions, leak-free SIS tunnel junctions were obtained, demonstrating the viability of this integrated ALD-UHV sputtering system for the fabrication of tunnel junctions and devices comprised of metal-dielectric-metal multilayers.

  11. Ultrahigh vacuum STM/STS studies of the Bi-O surface in Bi2Sr2CuOy single crystals

    International Nuclear Information System (INIS)

    Ikeda, Kazuto; Tomeno, Izumi; Takamuku, Kenshi; Yamaguchi, Koji; Itti, Rittaporn; Koshizuka, Naoki

    1992-01-01

    Scanning tunneling microscopic and spectroscopic studies were made on cleaved surfaces of Bi 2 Sr 2 CuO y single crystals using an ultrahigh-vacuum scanning tunneling microscope (UHV-STM). The modulation structures of the Bi-O surface were observed at room temperature with atomic resolution. The tunneling spectra showed electronic gap structures similar to those observed for the Bi-O surface of superconducting Bi-2212 single crystals. This suggests that superconductivity is not directly related to the electronic structure observed in the Bi-O plane. (orig.)

  12. Infrared spectroscopy of model electrochemical interfaces in ultrahigh vacuum: some implications for ionic and chemisorbate solvation at electrode surfaces

    Science.gov (United States)

    Villegas, Ignacio; Kizhakevariam, Naushad; Weaver, Michael J.

    1995-07-01

    The utility of infrared reflection-absorption spectroscopy (IRAS) for examining structure and bonding for model electrochemical interfaces in ultrahigh vacuum (UHV) is illustrated, focusing specifically on the solvation of cations and chemisorbed carbon monoxide on Pt(111). These systems were chosen partly in view of the availability of IRAS data (albeit limited to chemisorbate vibrations) for the corresponding in-situ metal-solution interfaces, enabling direct spectral comparisons to be made with the "UHV electrochemical model" systems. Kelvin probe measurements of the metal-UHV surface potential changes (ΔΦ) attending alterations in the interfacial composition are also described: these provide the required link to the in-situ electrode potentials as well as yielding additional insight into surface solvation. Variations in the negative electronic charge density and, correspondingly, in the cation surface concentration (thereby mimicking charge-induced alterations in the electrode potential below the potential of zero charge) are achieved by potassium atom dosage onto Pt(111). Of the solvents selected for discussion here — deuterated water, methanol, and acetonitrile — the first two exhibit readily detectable vibrational bands which provide information on the ionic solvation structure. Progressively dosing these solvents onto Pt(111) in the presence of low potassium coverages yields marked alterations in the solvent vibrational bands which can be understood in terms of sequential cation solvation. Comparison between these spectra for methanol with analogous data for sequential methanol solvation of gas-phase alkali cations enables the influence of the interfacial environment to be assessed. The effects of solvating chemisorbed CO are illustrated for acetonitrile; the markedly larger shifts in CO frequencies and binding sites for dilute CO adlayers can be accounted for in terms of short-range coadsorbate interactions in addition to longer-range Stark effects

  13. Ultrahigh vacuum dc magnetron sputter-deposition of epitaxial Pd(111)/Al2O3(0001) thin films.

    Science.gov (United States)

    Aleman, Angel; Li, Chao; Zaid, Hicham; Kindlund, Hanna; Fankhauser, Joshua; Prikhodko, Sergey V; Goorsky, Mark S; Kodambaka, Suneel

    2018-05-01

    Pd(111) thin films, ∼245 nm thick, are deposited on Al 2 O 3 (0001) substrates at ≈0.5 T m , where T m is the Pd melting point, by ultrahigh vacuum dc magnetron sputtering of Pd target in pure Ar discharges. Auger electron spectra and low-energy electron diffraction patterns acquired in situ from the as-deposited samples reveal that the surfaces are compositionally pure 111-oriented Pd. Double-axis x-ray diffraction (XRD) ω-2θ scans show only the set of Pd 111 peaks from the film. In triple-axis high-resolution XRD, the full width at half maximum intensity Γ ω of the Pd 111 ω-rocking curve is 630 arc sec. XRD 111 pole figure obtained from the sample revealed six peaks 60°-apart at a tilt angles corresponding to Pd 111 reflections. XRD ϕ scans show six 60°-rotated 111 peaks of Pd at the same ϕ angles for 11[Formula: see text]3 of Al 2 O 3 based on which the epitaxial crystallographic relationships between the film and the substrate are determined as [Formula: see text]ǁ[Formula: see text] with two in-plane orientations of [Formula: see text]ǁ[Formula: see text] and [Formula: see text]ǁ[Formula: see text]. Using triple axis symmetric and asymmetric reciprocal space maps, interplanar spacings of out-of-plane (111) and in-plane (11[Formula: see text]) are found to be 0.2242 ± 0.0003 and 0.1591 ± 0.0003 nm, respectively. These values are 0.18% lower than 0.2246 nm for (111) and the same, within the measurement uncertainties, as 0.1588 nm for (11[Formula: see text]) calculated from the bulk Pd lattice parameter, suggesting a small out-of-plane compressive strain and an in-plane tensile strain related to the thermal strain upon cooling the sample from the deposition temperature to room temperature. High-resolution cross-sectional transmission electron microscopy coupled with energy dispersive x-ray spectra obtained from the Pd(111)/Al 2 O 3 (0001) samples indicate that the Pd-Al 2 O 3 interfaces are essentially atomically abrupt and

  14. FOREWORD: The 4th CCM International Conference on Pressure Metrology from Ultra-High Vacuum to Very High Pressures (10-9 Pa to 109 Pa)

    Science.gov (United States)

    Legras, Jean-Claude; Jousten, Karl; Severn, Ian

    2005-12-01

    The fourth CCM (Consultative Committee for Mass and related quantities) International Conference on Pressure Metrology from Ultra-High Vacuum to Very High Pressures (10-9 Pa to 109 Pa) was held at the Institute of Physics in London from 19-21 April 2005. The event, which was organized by the Low, Medium and High Pressure working groups of the CCM, was attended by in excess of one hundred participants with representatives from five continents and every regional metrology organization. The purpose of this conference is to review all the work that is devoted to the highest quality of pressure measurement by primary standards as well as the dissemination of the pressure scale. A total of 52 papers were presented orally, and 26 as posters, in sessions that covered the following topics: Latest scientific advances in pressure and vacuum metrology Innovative transfer standards, advanced sensors and new instrument development Primary (top-level) measurement standards International and regional key comparisons New approaches to calibration It is interesting the note that since the third conference in 1999 the pressure range covered has increased by two orders of magnitude to 109 Pa, to take into account more exacting scientific and industrial demands for traceable vacuum measurement. A further feature of the conference was the increased range of instrumentation and techniques used in the realization and potential realization of pressure standards. Seton Bennett, Director of International Metrology at the National Physical Laboratory, opened the conference and Andrew Wallard, Director of the Bureau International des Poids et Mesures (BIPM), gave the keynote address which described the implementation of the mutual recognition arrangement and the resulting removal of metrological barriers to international trade. Many experts have contributed significant amounts of their time to organize the event and to review the submitted papers. Thanks are due to all of these people

  15. Set-up of a high-resolution 300 mK atomic force microscope in an ultra-high vacuum compatible "3He/10 T cryostat

    International Nuclear Information System (INIS)

    Allwörden, H. von; Ruschmeier, K.; Köhler, A.; Eelbo, T.; Schwarz, A.; Wiesendanger, R.

    2016-01-01

    The design of an atomic force microscope with an all-fiber interferometric detection scheme capable of atomic resolution at about 500 mK is presented. The microscope body is connected to a small pumped "3He reservoir with a base temperature of about 300 mK. The bakeable insert with the cooling stage can be moved from its measurement position inside the bore of a superconducting 10 T magnet into an ultra-high vacuum chamber, where the tip and sample can be exchanged in situ. Moreover, single atoms or molecules can be evaporated onto a cold substrate located inside the microscope. Two side chambers are equipped with standard surface preparation and surface analysis tools. The performance of the microscope at low temperatures is demonstrated by resolving single Co atoms on Mn/W(110) and by showing atomic resolution on NaCl(001).

  16. Low-temperature, ultrahigh-vacuum tip-enhanced Raman spectroscopy combined with molecular beam epitaxy for in situ two-dimensional materials' studies

    Science.gov (United States)

    Sheng, Shaoxiang; Li, Wenbin; Gou, Jian; Cheng, Peng; Chen, Lan; Wu, Kehui

    2018-05-01

    Tip-enhanced Raman spectroscopy (TERS), which combines scanning probe microscopy with the Raman spectroscopy, is capable to access the local structure and chemical information simultaneously. However, the application of ambient TERS is limited by the unstable and poorly controllable experimental conditions. Here, we designed a high performance TERS system based on a low-temperature ultrahigh-vacuum scanning tunneling microscope (LT-UHV-STM) and combined with a molecular beam epitaxy (MBE) system. It can be used for growing two-dimensional (2D) materials and for in situ STM and TERS characterization. Using a 2D silicene sheet on the Ag(111) surface as a model system, we achieved an unprecedented 109 Raman single enhancement factor in combination with a TERS spatial resolution down to 0.5 nm. The results show that TERS combined with a MBE system can be a powerful tool to study low dimensional materials and surface science.

  17. Local stabilization of single-walled carbon nanotubes on Si(100)-2 x 1:H via nanoscale hydrogen desorption with an ultrahigh vacuum scanning tunnelling microscope

    International Nuclear Information System (INIS)

    Albrecht, Peter M; Lyding, Joseph W

    2007-01-01

    An ultrahigh vacuum scanning tunnelling microscope (UHV-STM) was used to modify the interface between isolated ∼10 A-diameter single-walled carbon nanotubes (SWNTs) and the hydrogen-passivated Si(100) surface. Room-temperature UHV-STM desorption of hydrogen at the SWNT/H-Si(100) interface resulted in the local mechanical stabilization of tubes originally perturbed by the rastered STM tip under nominal imaging conditions. For the section of the SWNT contacted by depassivated Si, a topographic depression of 1.5 A (1 A) was measured in the case of parallel (nearly perpendicular) alignment between the tube axis and the Si dimer rows, in agreement with existing first-principles calculations. The compatibility of hydrogen-resist UHV-STM nanolithography with SWNTs adsorbed on H-Si(100) would enable the atomically precise placement of single molecules in proximity to the tube for the bottom-up fabrication of molecular electronic devices

  18. Set-up of a high-resolution 300 mK atomic force microscope in an ultra-high vacuum compatible {sup 3}He/10 T cryostat

    Energy Technology Data Exchange (ETDEWEB)

    Allwörden, H. von; Ruschmeier, K.; Köhler, A.; Eelbo, T.; Schwarz, A., E-mail: aschwarz@physnet.uni-hamburg.de; Wiesendanger, R. [Department of Physics, University of Hamburg, Jungiusstrasse 11, 20355 Hamburg (Germany)

    2016-07-15

    The design of an atomic force microscope with an all-fiber interferometric detection scheme capable of atomic resolution at about 500 mK is presented. The microscope body is connected to a small pumped {sup 3}He reservoir with a base temperature of about 300 mK. The bakeable insert with the cooling stage can be moved from its measurement position inside the bore of a superconducting 10 T magnet into an ultra-high vacuum chamber, where the tip and sample can be exchanged in situ. Moreover, single atoms or molecules can be evaporated onto a cold substrate located inside the microscope. Two side chambers are equipped with standard surface preparation and surface analysis tools. The performance of the microscope at low temperatures is demonstrated by resolving single Co atoms on Mn/W(110) and by showing atomic resolution on NaCl(001).

  19. A compact Ultra-High Vacuum (UHV) compatible instrument for time of flight-energy measurements of slow heavy reaction products

    Energy Technology Data Exchange (ETDEWEB)

    Kuznetsov, A.V.; Veldhuizen, E.J. van; Westerberg, L.; Lyapin, V.G.; Aleklett, K.; Loveland, W.; Bondorf, J.; Jakobsson, B.; Whitlow, H.J.; El Bouanani, M

    2000-10-01

    A compact Ultra-High Vacuum (UHV) compatible instrument for time of flight-energy measurements of slow heavy reaction products from nuclear reactions has been designed and tested at the CELSIUS storage ring in Uppsala. The construction is based on MicroChannel Plate (MCP) time detectors of the electron mirror type and silicon p-i-n diodes, and permits the detectors to be stacked side-by-side to achieve large solid angle coverage. This kind of telescope measures the Time of Flight (ToF) and Energy (E) of the particle from which one can reconstruct mass. The combination of an ultra-thin cluster gas-jet target and thin carbon emitter foils allows one to measure heavy residues down to an energy of {approx}35 keV/nucleon from the interactions of 400 MeV/nucleon {sup 16}O with {sup nat}Xe gas targets.

  20. A compact Ultra-High Vacuum (UHV) compatible instrument for time of flight-energy measurements of slow heavy reaction products

    International Nuclear Information System (INIS)

    Kuznetsov, A.V.; Veldhuizen, E.J. van; Westerberg, L.; Lyapin, V.G.; Aleklett, K.; Loveland, W.; Bondorf, J.; Jakobsson, B.; Whitlow, H.J.; El Bouanani, M.

    2000-01-01

    A compact Ultra-High Vacuum (UHV) compatible instrument for time of flight-energy measurements of slow heavy reaction products from nuclear reactions has been designed and tested at the CELSIUS storage ring in Uppsala. The construction is based on MicroChannel Plate (MCP) time detectors of the electron mirror type and silicon p-i-n diodes, and permits the detectors to be stacked side-by-side to achieve large solid angle coverage. This kind of telescope measures the Time of Flight (ToF) and Energy (E) of the particle from which one can reconstruct mass. The combination of an ultra-thin cluster gas-jet target and thin carbon emitter foils allows one to measure heavy residues down to an energy of ∼35 keV/nucleon from the interactions of 400 MeV/nucleon 16 O with nat Xe gas targets

  1. Ultrahigh vacuum and high-pressure coadsorption of CO and H2 on Pd(111): A combined SFG, TDS, and LEED study

    Science.gov (United States)

    Morkel, Matthias; Rupprechter, Günther; Freund, Hans-Joachim

    2003-11-01

    Sum frequency generation (SFG) vibrational spectroscopy was carried out in conjunction with thermal desorption spectroscopy, low-energy electron diffraction, and Auger electron spectroscopy to examine the coadsorption of CO and H2 on Pd(111). Sequential dosing as well as various CO/H2 mixtures was utilized to study intermolecular interactions between CO and H2. Preadsorbed CO effectively prevented the dissociative adsorption of hydrogen for CO coverages ⩾0.33 ML. While preadsorbed hydrogen was able to hinder CO adsorption at low temperature (100 K), hydrogen was replaced from the surface by CO at 150 K. When 1:1 mixtures of CO/H2 were used at 100 K, hydrogen selectively hindered CO adsorption on on-top sites, while above ˜125 K no blocking of CO adsorption was observed. The observations are explained in terms of mutual site blocking, of a CO-H phase separation, and of a CO-assisted hydrogen dissolution in the Pd bulk. The temperature-dependent site blocking effect of hydrogen is attributed to the ability (inability) of surface hydrogen to diffuse into the Pd bulk above (below) ˜125 K. Nonlinear optical SFG spectroscopy allowed us to study these effects not only in ultrahigh vacuum but also in a high-pressure environment. Using an SFG-compatible ultrahigh vacuum-high-pressure cell, spectra of 1:10 CO/H2 mixtures were acquired up to 55 mbar and 550 K, with simultaneous gas chromatographic and mass spectrometric gas phase analysis. Under reaction conditions, CO coverages ⩾0.5 ML were observed which strongly limit H2 adsorption and thus may be partly responsible for the low CO hydrogenation rate. The high-pressure and high-temperature SFG spectra also showed indications of a reversible surface roughening or a highly dynamic (not perfectly ordered) CO adsorbate phase. Implications of the observed adsorbate structures on catalytic CO hydrogenation on supported Pd nanoparticles are discussed.

  2. Ultrahigh vacuum and high-pressure coadsorption of CO and H2 on Pd(111): A combined SFG, TDS, and LEED study

    International Nuclear Information System (INIS)

    Morkel, Matthias; Rupprechter, Guenther; Freund, Hans-Joachim

    2003-01-01

    Sum frequency generation (SFG) vibrational spectroscopy was carried out in conjunction with thermal desorption spectroscopy, low-energy electron diffraction, and Auger electron spectroscopy to examine the coadsorption of CO and H 2 on Pd(111). Sequential dosing as well as various CO/H 2 mixtures was utilized to study intermolecular interactions between CO and H 2 . Preadsorbed CO effectively prevented the dissociative adsorption of hydrogen for CO coverages ≥0.33 ML. While preadsorbed hydrogen was able to hinder CO adsorption at low temperature (100 K), hydrogen was replaced from the surface by CO at 150 K. When 1:1 mixtures of CO/H 2 were used at 100 K, hydrogen selectively hindered CO adsorption on on-top sites, while above ∼125 K no blocking of CO adsorption was observed. The observations are explained in terms of mutual site blocking, of a CO-H phase separation, and of a CO-assisted hydrogen dissolution in the Pd bulk. The temperature-dependent site blocking effect of hydrogen is attributed to the ability (inability) of surface hydrogen to diffuse into the Pd bulk above (below) ∼125 K. Nonlinear optical SFG spectroscopy allowed us to study these effects not only in ultrahigh vacuum but also in a high-pressure environment. Using an SFG-compatible ultrahigh vacuum-high-pressure cell, spectra of 1:10 CO/H 2 mixtures were acquired up to 55 mbar and 550 K, with simultaneous gas chromatographic and mass spectrometric gas phase analysis. Under reaction conditions, CO coverages ≥0.5 ML were observed which strongly limit H 2 adsorption and thus may be partly responsible for the low CO hydrogenation rate. The high-pressure and high-temperature SFG spectra also showed indications of a reversible surface roughening or a highly dynamic (not perfectly ordered) CO adsorbate phase. Implications of the observed adsorbate structures on catalytic CO hydrogenation on supported Pd nanoparticles are discussed

  3. Vacuum phonon tunneling.

    Science.gov (United States)

    Altfeder, Igor; Voevodin, Andrey A; Roy, Ajit K

    2010-10-15

    Field-induced phonon tunneling, a previously unknown mechanism of interfacial thermal transport, has been revealed by ultrahigh vacuum inelastic scanning tunneling microscopy (STM). Using thermally broadened Fermi-Dirac distribution in the STM tip as in situ atomic-scale thermometer we found that thermal vibrations of the last tip atom are effectively transmitted to sample surface despite few angstroms wide vacuum gap. We show that phonon tunneling is driven by interfacial electric field and thermally vibrating image charges, and its rate is enhanced by surface electron-phonon interaction.

  4. Realisation of a ultra-high vacuum system and technique development of microscopical emitters preparation in silicium. First measurements of field emission current and field photoemission

    International Nuclear Information System (INIS)

    El Manouni, A.

    1990-12-01

    The development of research in the domain of photocathode (electron sources) illuminated by laser light to produce intense multiple bunches of electrons in short time is needed by many applications as linear collider e + e - , free electron laser, lasertron, etc... In this way, after a study of field emission, of photoemission and of photofield emission, we prepared microscopical emitters in silicium heavy and weakly doped a boron using a technique of microlithography. Then, we realized a system of ultra-high vacuum of studying property of emission from photocathodes realized. The experiment results obtained in field emission and photofield emission have shown that a behaviour unexpected for P-silicium tips array compared to P + -silicon tips array. With P-type silicon, a quantum yield of 21 percent has been measured for laser power of 140 mW and for applied field of 1.125 x 10 7 V/m and an instantaneous response to laser light beam has been observed. It has been noted that presence of oxyde at the surface of photocathode limits extensively the emission current. The fluctuations of emission current are due to quality of vacuum [fr

  5. High field electron paramagnetic resonance spectroscopy under ultrahigh vacuum conditions—A multipurpose machine to study paramagnetic species on well defined single crystal surfaces

    Energy Technology Data Exchange (ETDEWEB)

    Rocker, J.; Cornu, D.; Kieseritzky, E.; Hänsel-Ziegler, W.; Freund, H.-J. [Fritz-Haber-Institut der MPG, Faradayweg 4-6, 14195 Berlin (Germany); Seiler, A. [Fritz-Haber-Institut der MPG, Faradayweg 4-6, 14195 Berlin (Germany); Laboratorium für Applikationen der Synchrotronstrahlung, KIT Campus Süd, Kaiserstr. 12, 76131 Karlsruhe (Germany); Bondarchuk, O. [Fritz-Haber-Institut der MPG, Faradayweg 4-6, 14195 Berlin (Germany); CIC energiGUNE, Parque Tecnologico, C/Albert Einstein 48, CP 01510 Minano (Alava) (Spain); Risse, T., E-mail: risse@chemie.fu-berlin.de [Fritz-Haber-Institut der MPG, Faradayweg 4-6, 14195 Berlin (Germany); Institut für Chemie und Biochemie, Freie Universität Berlin, Takustr. 3, 14195 Berlin (Germany)

    2014-08-01

    A new ultrahigh vacuum (UHV) electron paramagnetic resonance (EPR) spectrometer operating at 94 GHz to investigate paramagnetic centers on single crystal surfaces is described. It is particularly designed to study paramagnetic centers on well-defined model catalysts using epitaxial thin oxide films grown on metal single crystals. The EPR setup is based on a commercial Bruker E600 spectrometer, which is adapted to ultrahigh vacuum conditions using a home made Fabry Perot resonator. The key idea of the resonator is to use the planar metal single crystal required to grow the single crystalline oxide films as one of the mirrors of the resonator. EPR spectroscopy is solely sensitive to paramagnetic species, which are typically minority species in such a system. Hence, additional experimental characterization tools are required to allow for a comprehensive investigation of the surface. The apparatus includes a preparation chamber hosting equipment, which is required to prepare supported model catalysts. In addition, surface characterization tools such as low energy electron diffraction (LEED)/Auger spectroscopy, temperature programmed desorption (TPD), and infrared reflection absorption spectroscopy (IRAS) are available to characterize the surfaces. A second chamber used to perform EPR spectroscopy at 94 GHz has a room temperature scanning tunneling microscope attached to it, which allows for real space structural characterization. The heart of the UHV adaptation of the EPR experiment is the sealing of the Fabry-Perot resonator against atmosphere. To this end it is possible to use a thin sapphire window glued to the backside of the coupling orifice of the Fabry Perot resonator. With the help of a variety of stabilization measures reducing vibrations as well as thermal drift it is possible to accumulate data for a time span, which is for low temperature measurements only limited by the amount of liquid helium. Test measurements show that the system can detect paramagnetic

  6. ZnO nanocrystals on SiO2/Si surfaces thermally cleaned in ultrahigh vacuum and characterized using spectroscopic photoemission and low energy electron microscopy

    International Nuclear Information System (INIS)

    Ericsson, Leif K. E.; Magnusson, Kjell O.; Zakharov, Alexei A.

    2010-01-01

    Thermal cleaning in ultrahigh vacuum of ZnO nanocrystals distributed on SiO 2 /Si surfaces has been studied using spectroscopic photoemission and low energy electron microscopy (SPELEEM). This study thus concern weakly bound ZnO nanocrystals covering only 5%-10% of the substrate. Chemical properties, crystallinity, and distribution of nanocrystals are used to correlate images acquired with the different techniques showing excellent correspondence. The nanocrystals are shown to be clean enough after thermal cleaning at 650 deg. C to be imaged by LEEM and x-ray PEEM as well as chemically analyzed by site selective x-ray photoelectron spectroscopy (μ-XPS). μ-XPS shows a sharp Zn 3d peak and resolve differences in O 1s states in oxides. The strong LEEM reflections together with the obtained chemical information indicates that the ZnO nanocrystals were thermally cleaned, but do not indicate any decomposition of the nanocrystals. μ-XPS was also used to determine the thickness of SiO 2 on Si. This article is the first to our knowledge where the versatile technique SPELEEM has been used to characterize ZnO nanocrystals.

  7. Design and performance of an ultra-high vacuum spin-polarized scanning tunneling microscope operating at 30 mK and in a vector magnetic field.

    Science.gov (United States)

    von Allwörden, Henning; Eich, Andreas; Knol, Elze J; Hermenau, Jan; Sonntag, Andreas; Gerritsen, Jan W; Wegner, Daniel; Khajetoorians, Alexander A

    2018-03-01

    We describe the design and performance of a scanning tunneling microscope (STM) that operates at a base temperature of 30 mK in a vector magnetic field. The cryogenics is based on an ultra-high vacuum (UHV) top-loading wet dilution refrigerator that contains a vector magnet allowing for fields up to 9 T perpendicular and 4 T parallel to the sample. The STM is placed in a multi-chamber UHV system, which allows in situ preparation and exchange of samples and tips. The entire system rests on a 150-ton concrete block suspended by pneumatic isolators, which is housed in an acoustically isolated and electromagnetically shielded laboratory optimized for extremely low noise scanning probe measurements. We demonstrate the overall performance by illustrating atomic resolution and quasiparticle interference imaging and detail the vibrational noise of both the laboratory and microscope. We also determine the electron temperature via measurement of the superconducting gap of Re(0001) and illustrate magnetic field-dependent measurements of the spin excitations of individual Fe atoms on Pt(111). Finally, we demonstrate spin resolution by imaging the magnetic structure of the Fe double layer on W(110).

  8. An ultrahigh-vacuum cryostat for simultaneous scanning tunneling microscopy and magneto-transport measurements down to 400 mK.

    Science.gov (United States)

    Liebmann, Marcus; Bindel, Jan Raphael; Pezzotta, Mike; Becker, Stefan; Muckel, Florian; Johnsen, Tjorven; Saunus, Christian; Ast, Christian R; Morgenstern, Markus

    2017-12-01

    We present the design and calibration measurements of a scanning tunneling microscope setup in a 3 He ultrahigh-vacuum cryostat operating at 400 mK with a hold time of 10 days. With 2.70 m in height and 4.70 m free space needed for assembly, the cryostat fits in a one-story lab building. The microscope features optical access, an xy table, in situ tip and sample exchange, and enough contacts to facilitate atomic force microscopy in tuning fork operation and simultaneous magneto-transport measurements on the sample. Hence, it enables scanning tunneling spectroscopy on microstructured samples which are tuned into preselected transport regimes. A superconducting magnet provides a perpendicular field of up to 14 T. The vertical noise of the scanning tunneling microscope amounts to 1 pm rms within a 700 Hz bandwidth. Tunneling spectroscopy using one superconducting electrode revealed an energy resolution of 120 μeV. Data on tip-sample Josephson contacts yield an even smaller feature size of 60 μeV, implying that the system operates close to the physical noise limit.

  9. Design and performance of an ultra-high vacuum scanning tunneling microscope operating at dilution refrigerator temperatures and high magnetic fields.

    Science.gov (United States)

    Misra, S; Zhou, B B; Drozdov, I K; Seo, J; Urban, L; Gyenis, A; Kingsley, S C J; Jones, H; Yazdani, A

    2013-10-01

    We describe the construction and performance of a scanning tunneling microscope capable of taking maps of the tunneling density of states with sub-atomic spatial resolution at dilution refrigerator temperatures and high (14 T) magnetic fields. The fully ultra-high vacuum system features visual access to a two-sample microscope stage at the end of a bottom-loading dilution refrigerator, which facilitates the transfer of in situ prepared tips and samples. The two-sample stage enables location of the best area of the sample under study and extends the experiment lifetime. The successful thermal anchoring of the microscope, described in detail, is confirmed through a base temperature reading of 20 mK, along with a measured electron temperature of 250 mK. Atomically resolved images, along with complementary vibration measurements, are presented to confirm the effectiveness of the vibration isolation scheme in this instrument. Finally, we demonstrate that the microscope is capable of the same level of performance as typical machines with more modest refrigeration by measuring spectroscopic maps at base temperature both at zero field and in an applied magnetic field.

  10. Design and performance of an ultra-high vacuum spin-polarized scanning tunneling microscope operating at 30 mK and in a vector magnetic field

    Science.gov (United States)

    von Allwörden, Henning; Eich, Andreas; Knol, Elze J.; Hermenau, Jan; Sonntag, Andreas; Gerritsen, Jan W.; Wegner, Daniel; Khajetoorians, Alexander A.

    2018-03-01

    We describe the design and performance of a scanning tunneling microscope (STM) that operates at a base temperature of 30 mK in a vector magnetic field. The cryogenics is based on an ultra-high vacuum (UHV) top-loading wet dilution refrigerator that contains a vector magnet allowing for fields up to 9 T perpendicular and 4 T parallel to the sample. The STM is placed in a multi-chamber UHV system, which allows in situ preparation and exchange of samples and tips. The entire system rests on a 150-ton concrete block suspended by pneumatic isolators, which is housed in an acoustically isolated and electromagnetically shielded laboratory optimized for extremely low noise scanning probe measurements. We demonstrate the overall performance by illustrating atomic resolution and quasiparticle interference imaging and detail the vibrational noise of both the laboratory and microscope. We also determine the electron temperature via measurement of the superconducting gap of Re(0001) and illustrate magnetic field-dependent measurements of the spin excitations of individual Fe atoms on Pt(111). Finally, we demonstrate spin resolution by imaging the magnetic structure of the Fe double layer on W(110).

  11. Ge quantum dot arrays grown by ultrahigh vacuum molecular-beam epitaxy on the Si(001) surface: nucleation, morphology, and CMOS compatibility.

    Science.gov (United States)

    Yuryev, Vladimir A; Arapkina, Larisa V

    2011-09-05

    Issues of morphology, nucleation, and growth of Ge cluster arrays deposited by ultrahigh vacuum molecular beam epitaxy on the Si(001) surface are considered. Difference in nucleation of quantum dots during Ge deposition at low (≲600°C) and high (≳600°C) temperatures is studied by high resolution scanning tunneling microscopy. The atomic models of growth of both species of Ge huts--pyramids and wedges-- are proposed. The growth cycle of Ge QD arrays at low temperatures is explored. A problem of lowering of the array formation temperature is discussed with the focus on CMOS compatibility of the entire process; a special attention is paid upon approaches to reduction of treatment temperature during the Si(001) surface pre-growth cleaning, which is at once a key and the highest-temperature phase of the Ge/Si(001) quantum dot dense array formation process. The temperature of the Si clean surface preparation, the final high-temperature step of which is, as a rule, carried out directly in the MBE chamber just before the structure deposition, determines the compatibility of formation process of Ge-QD-array based devices with the CMOS manufacturing cycle. Silicon surface hydrogenation at the final stage of its wet chemical etching during the preliminary cleaning is proposed as a possible way of efficient reduction of the Si wafer pre-growth annealing temperature.

  12. An ultrahigh-vacuum apparatus for resonant diffraction experiments using soft x rays (hν=300-2000 eV)

    International Nuclear Information System (INIS)

    Takeuchi, T.; Chainani, A.; Takata, Y.; Tanaka, Y.; Oura, M.; Tsubota, M.; Senba, Y.; Ohashi, H.; Mochiku, T.; Hirata, K.; Shin, S.

    2009-01-01

    We have developed an ultrahigh-vacuum instrument for resonant diffraction experiments using polarized soft x rays in the energy range of hν=300-2000 eV at beamline BL17SU of SPring-8. The diffractometer consists of modified differentially pumped rotary feedthroughs for θ-2θ stages, a sample manipulator with motor-controlled x-y-z-, tilt (χ)-, and azimuth (φ)-axes, and a liquid helium flow-type cryostat for temperature dependent measurements between 30 and 300 K. Test results indicate that the diffractometer exhibits high reproducibility (better than 0.001 deg.) for a Bragg reflection of α-quartz 100 at a photon energy of hν=1950 eV. Typical off- and on-resonance Bragg reflections in the energy range of 530-1950 eV could be measured using the apparatus. The results show that x-ray diffraction experiments with energy-, azimuth-, and incident photon polarization-dependence can be reliably measured using soft x rays in the energy range of ∼300-2000 eV. The facility can be used for resonant diffraction experiments across the L-edge of transition metals, M-edge of lanthanides, and up to the Si K-edge of materials.

  13. Ge quantum dot arrays grown by ultrahigh vacuum molecular-beam epitaxy on the Si(001 surface: nucleation, morphology, and CMOS compatibility

    Directory of Open Access Journals (Sweden)

    Yuryev Vladimir

    2011-01-01

    Full Text Available Abstract Issues of morphology, nucleation, and growth of Ge cluster arrays deposited by ultrahigh vacuum molecular beam epitaxy on the Si(001 surface are considered. Difference in nucleation of quantum dots during Ge deposition at low (≲600°C and high (≳600°C temperatures is studied by high resolution scanning tunneling microscopy. The atomic models of growth of both species of Ge huts--pyramids and wedges-- are proposed. The growth cycle of Ge QD arrays at low temperatures is explored. A problem of lowering of the array formation temperature is discussed with the focus on CMOS compatibility of the entire process; a special attention is paid upon approaches to reduction of treatment temperature during the Si(001 surface pre-growth cleaning, which is at once a key and the highest-temperature phase of the Ge/Si(001 quantum dot dense array formation process. The temperature of the Si clean surface preparation, the final high-temperature step of which is, as a rule, carried out directly in the MBE chamber just before the structure deposition, determines the compatibility of formation process of Ge-QD-array based devices with the CMOS manufacturing cycle. Silicon surface hydrogenation at the final stage of its wet chemical etching during the preliminary cleaning is proposed as a possible way of efficient reduction of the Si wafer pre-growth annealing temperature.

  14. CHICSi - a compact ultra-high vacuum compatible detector system for nuclear reaction experiments at storage rings. I. General structure, mechanics and UHV compatibility

    International Nuclear Information System (INIS)

    Westerberg, L.; Avdeichikov, V.; Carlen, L.; Golubev, P.; Jakobsson, B.; Rouki, C.; Siwek, A.; Veldhuizen, E.J. van; Whitlow, H.J.

    2003-01-01

    CELSIUS Heavy-Ion Collision Silicon detector system (CHICSi) is a large solid angle, barrel-shaped detector system, housing up to 600 detector telescopes arranged in rotational symmetry around the beam axis. CHICSi measures charged particles and fragments from nuclear reactions. It operates at internal targets of storage rings. In order to optimize space and momentum-space coverage and minimize the low-energy detection limits, CHICSi is designed for use in ultra-high vacuum (UHV, ∼10 -8 Pa) inside a cluster-jet target chamber. This calls for materials in mechanical support, detectors, Very Large Scale Integrated (VLSI) electronics, connectors, cables and other signal transport devices with very low outgassing. Two auxiliary detector systems, which will operate in coincidence with CHICSi, a heavy-recoil, time-of-flight system (HR-TOF) also placed inside the target chamber and a projectile fragmentation wall (PF-WALL) located outside the chamber, have also been constructed. In total, this combined system registers more than 80% of all charged particles and fragments from typical heavy-ion reactions at energies of a few hundreds of MeV per nucleon

  15. CHICSi - a compact ultra-high vacuum compatible detector system for nuclear reaction experiments at storage rings. I. General structure, mechanics and UHV compatibility

    Energy Technology Data Exchange (ETDEWEB)

    Westerberg, L.; Avdeichikov, V.; Carlen, L.; Golubev, P.; Jakobsson, B. E-mail: bo.jakobsson@kosufy.lu.se; Rouki, C.; Siwek, A.; Veldhuizen, E.J. van; Whitlow, H.J

    2003-03-11

    CELSIUS Heavy-Ion Collision Silicon detector system (CHICSi) is a large solid angle, barrel-shaped detector system, housing up to 600 detector telescopes arranged in rotational symmetry around the beam axis. CHICSi measures charged particles and fragments from nuclear reactions. It operates at internal targets of storage rings. In order to optimize space and momentum-space coverage and minimize the low-energy detection limits, CHICSi is designed for use in ultra-high vacuum (UHV, {approx}10{sup -8} Pa) inside a cluster-jet target chamber. This calls for materials in mechanical support, detectors, Very Large Scale Integrated (VLSI) electronics, connectors, cables and other signal transport devices with very low outgassing. Two auxiliary detector systems, which will operate in coincidence with CHICSi, a heavy-recoil, time-of-flight system (HR-TOF) also placed inside the target chamber and a projectile fragmentation wall (PF-WALL) located outside the chamber, have also been constructed. In total, this combined system registers more than 80% of all charged particles and fragments from typical heavy-ion reactions at energies of a few hundreds of MeV per nucleon.

  16. An ultrahigh-vacuum cryostat for simultaneous scanning tunneling microscopy and magneto-transport measurements down to 400 mK

    Science.gov (United States)

    Liebmann, Marcus; Bindel, Jan Raphael; Pezzotta, Mike; Becker, Stefan; Muckel, Florian; Johnsen, Tjorven; Saunus, Christian; Ast, Christian R.; Morgenstern, Markus

    2017-12-01

    We present the design and calibration measurements of a scanning tunneling microscope setup in a 3He ultrahigh-vacuum cryostat operating at 400 mK with a hold time of 10 days. With 2.70 m in height and 4.70 m free space needed for assembly, the cryostat fits in a one-story lab building. The microscope features optical access, an xy table, in situ tip and sample exchange, and enough contacts to facilitate atomic force microscopy in tuning fork operation and simultaneous magneto-transport measurements on the sample. Hence, it enables scanning tunneling spectroscopy on microstructured samples which are tuned into preselected transport regimes. A superconducting magnet provides a perpendicular field of up to 14 T. The vertical noise of the scanning tunneling microscope amounts to 1 pmrms within a 700 Hz bandwidth. Tunneling spectroscopy using one superconducting electrode revealed an energy resolution of 120 μeV. Data on tip-sample Josephson contacts yield an even smaller feature size of 60 μeV, implying that the system operates close to the physical noise limit.

  17. An ultra-high vacuum scanning tunneling microscope operating at sub-Kelvin temperatures and high magnetic fields for spin-resolved measurements

    Science.gov (United States)

    Salazar, C.; Baumann, D.; Hänke, T.; Scheffler, M.; Kühne, T.; Kaiser, M.; Voigtländer, R.; Lindackers, D.; Büchner, B.; Hess, C.

    2018-06-01

    We present the construction and performance of an ultra-low-temperature scanning tunneling microscope (STM), working in ultra-high vacuum (UHV) conditions and in high magnetic fields up to 9 T. The cryogenic environment of the STM is generated by a single-shot 3He magnet cryostat in combination with a 4He dewar system. At a base temperature (300 mK), the cryostat has an operation time of approximately 80 h. The special design of the microscope allows the transfer of the STM head from the cryostat to a UHV chamber system, where samples and STM tips can be easily exchanged. The UHV chambers are equipped with specific surface science treatment tools for the functionalization of samples and tips, including high-temperature treatments and thin film deposition. This, in particular, enables spin-resolved tunneling measurements. We present test measurements using well-known samples and tips based on superconductors and metallic materials such as LiFeAs, Nb, Fe, and W. The measurements demonstrate the outstanding performance of the STM with high spatial and energy resolution as well as the spin-resolved capability.

  18. CHICSi--a compact ultra-high vacuum compatible detector system for nuclear reaction experiments at storage rings. III. readout system

    Energy Technology Data Exchange (ETDEWEB)

    Carlen, L.; Foerre, G.; Golubev, P.; Jakobsson, B. E-mail: bo.jakobsson@kosufy.lu.se; Kolozhvari, A.; Marciniewski, P.; Siwek, A.; Veldhuizen, E.J. van; Westerberg, L.; Whitlow, H.J.; Oestby, J.M

    2004-01-11

    (CHICSi) Celsius Heavy Ion Collaboration Si detector system is a high granularity, modular detector telescope array for operation around the cluster-jet target/circulating beam intersection of the CELSIUS storage ring at the The. Svedberg Laboratory in Uppsala, Sweden. It is able to provide identity and momentum vector of up to 100 charged particles and fragments from proton-nucleus and nucleus-nucleus collisions at intermediate energies, 50-1000A MeV. All detector telescopes as well as the major part of electronic readout system are placed inside the target chamber in ultra-high vacuum (UHV, 10{sup -9}-10{sup -7} Pa). This requires Very Large Scale Integrated (VLSI) microchip for the spectroscopic signal processing and the generation and transport of digital control signals. Eighteen telescopes, read out with chip-on-board technique by ceramics Mother Boards (MB) and corresponding 18 microchips are mounted on a 450x45 mm{sup 2} Grand Mother Board (GMB), processed on FR4 glass-fibre material. Each of these 28 GMB units contains a daisy-chain organisation of the VLSI chips and associated protection circuits. Analogue-to-digital conversion of the spectroscopic signals is performed on a board outside the chamber which is connected on one side to a power distribution board, directly attached to a UHV mounting flange, and on the other side to the VME-based data acquisition system (CHICSiDAQ). This in its turn is connected via a fibre-optic link to the general TSL acquisition system (SVEDAQ), and in this way data from auxiliary detector systems, read out in CAMAC mode, can be stored in coincidence with CHICSi data.

  19. CHICSi--a compact ultra-high vacuum compatible detector system for nuclear reaction experiments at storage rings. III. readout system

    International Nuclear Information System (INIS)

    Carlen, L.; Foerre, G.; Golubev, P.; Jakobsson, B.; Kolozhvari, A.; Marciniewski, P.; Siwek, A.; Veldhuizen, E.J. van; Westerberg, L.; Whitlow, H.J.; Oestby, J.M.

    2004-01-01

    (CHICSi) Celsius Heavy Ion Collaboration Si detector system is a high granularity, modular detector telescope array for operation around the cluster-jet target/circulating beam intersection of the CELSIUS storage ring at the The. Svedberg Laboratory in Uppsala, Sweden. It is able to provide identity and momentum vector of up to 100 charged particles and fragments from proton-nucleus and nucleus-nucleus collisions at intermediate energies, 50-1000A MeV. All detector telescopes as well as the major part of electronic readout system are placed inside the target chamber in ultra-high vacuum (UHV, 10 -9 -10 -7 Pa). This requires Very Large Scale Integrated (VLSI) microchip for the spectroscopic signal processing and the generation and transport of digital control signals. Eighteen telescopes, read out with chip-on-board technique by ceramics Mother Boards (MB) and corresponding 18 microchips are mounted on a 450x45 mm 2 Grand Mother Board (GMB), processed on FR4 glass-fibre material. Each of these 28 GMB units contains a daisy-chain organisation of the VLSI chips and associated protection circuits. Analogue-to-digital conversion of the spectroscopic signals is performed on a board outside the chamber which is connected on one side to a power distribution board, directly attached to a UHV mounting flange, and on the other side to the VME-based data acquisition system (CHICSiDAQ). This in its turn is connected via a fibre-optic link to the general TSL acquisition system (SVEDAQ), and in this way data from auxiliary detector systems, read out in CAMAC mode, can be stored in coincidence with CHICSi data

  20. Experimental study of metal gasketed joints for ultra-high vacuums; Etude experimentale de joints metalliques pour ultra-vide

    Energy Technology Data Exchange (ETDEWEB)

    Boulloud, J. P.; Schweitzer, J. [Commissariat a l' energie atomique et aux energies alternatives - CEA, Service de Physique Appliquee, groupe de Vide, Centre d' Etudes Nucleaires de Saclay (France)

    1960-07-01

    Various type of leak-tight metal joints have been studied with their application in assemblies containing total vacuums in mind. Their integrity has been tested with a helium leak detector, and leaks of about 2 x 10{sup -12} cm{sup 3} Atm/s per meter of joint have been measured, simultaneously with the clamping effort applied at the joint and the deformation of the metal gasket. The integrity to clamping effort ratio curve is not retraced in reverse upon relaxation of the clamping effort, but a 'return curve' analogous to a hysteresis cycle explains why certain types of joint retain their integrity at high temperatures. The use of a tracer gas permits discrimination between external permeation of the joint and gas from occlusions between its mating surfaces. The authors have been led to consider that neither the nature nor the purity or surface condition of the joint have any basic influence on its integrity. Clamping effort values in respect of various joints and necessary for total integrity are indicated. Reprint of a paper published in Le vide, no. 82, Jul-Aug 1959 [French] L'etude de differents types de joints metalliques etanches, en vue de leur application a l'ultra-vide, a ete effectuee a l'aide d'un detecteur de fuite a helium. On a mesure simultanement le debit de fuite, l'effort applique sur le joint et sa deformation. On a reussi a mesurer des debits de fuite de l'ordre de 2 x 10{sup -12} cm{sup 3} Atm/s/m de joint pour l'air. La courbe de l'etancheite en fonction de l'effort applique n'est pas reversible et on a pu mettre en evidence un 'cycle d'hysteresis' qui explique que certains joints conservent leur etancheite a haute temperature. La methode de mesure d'etancheite au moyen d'un gaz traceur a amene a faire une distinction entre la permeation et le degazage des gaz occlus dans l'interface des joints et a considerer que ni la nature, ni la purete et ni l'etat de surface du joint n'ont une influence primordiale sur l'etancheite de joint. Des valeurs

  1. Evaluation of Vapor Pressure and Ultra-High Vacuum Tribological Properties of Ionic Liquids (2) Mixtures and Additives

    Science.gov (United States)

    Morales, Wilfredo; Koch, Victor R.; Street, Kenneth W., Jr.; Richard, Ryan M.

    2008-01-01

    Ionic liquids are salts, many of which are typically viscous fluids at room temperature. The fluids are characterized by negligible vapor pressures under ambient conditions. These properties have led us to study the effectiveness of ionic liquids containing both organic cations and anions for use as space lubricants. In the previous paper we have measured the vapor pressure and some tribological properties of two distinct ionic liquids under simulated space conditions. In this paper we will present vapor pressure measurements for two new ionic liquids and friction coefficient data for boundary lubrication conditions in a spiral orbit tribometer using stainless steel tribocouples. In addition we present the first tribological data on mixed ionic liquids and an ionic liquid additive. Post mortem infrared and Raman analysis of the balls and races indicates the major degradation pathway for these two organic ionic liquids is similar to those of other carbon based lubricants, i.e. deterioration of the organic structure into amorphous graphitic carbon. The coefficients of friction and lifetimes of these lubricants are comparable to or exceed these properties for several commonly used space oils.

  2. Industry-relevant magnetron sputtering and cathodic arc ultra-high vacuum deposition system for in situ x-ray diffraction studies of thin film growth using high energy synchrotron radiation

    OpenAIRE

    Schroeder, Jeremy; Thomson, W.; Howard, B.; Schell, N.; Näslund, Lars-Åke; Rogström, Lina; Johansson-Jöesaar, Mats P.; Ghafoor, Naureen; Odén, Magnus; Nothnagel, E.; Shepard, A.; Greer, J.; Birch, Jens

    2015-01-01

    We present an industry-relevant, large-scale, ultra-high vacuum (UHV) magnetron sputtering and cathodic arc deposition system purposefully designed for time-resolved in situ thin film deposition/annealing studies using high-energy (greater than50 keV), high photon flux (greater than10(12) ph/s) synchrotron radiation. The high photon flux, combined with a fast-acquisition-time (less than1 s) two-dimensional (2D) detector, permits time-resolved in situ structural analysis of thin film formation...

  3. Industry-relevant magnetron sputtering and cathodic arc ultra-high vacuum deposition system for in situ x-ray diffraction studies of thin film growth using high energy synchrotron radiation.

    Science.gov (United States)

    Schroeder, J L; Thomson, W; Howard, B; Schell, N; Näslund, L-Å; Rogström, L; Johansson-Jõesaar, M P; Ghafoor, N; Odén, M; Nothnagel, E; Shepard, A; Greer, J; Birch, J

    2015-09-01

    We present an industry-relevant, large-scale, ultra-high vacuum (UHV) magnetron sputtering and cathodic arc deposition system purposefully designed for time-resolved in situ thin film deposition/annealing studies using high-energy (>50 keV), high photon flux (>10(12) ph/s) synchrotron radiation. The high photon flux, combined with a fast-acquisition-time (film formation processes. The high-energy synchrotron-radiation based x-rays result in small scattering angles (industry-relevant processes. We openly encourage the materials research community to contact us for collaborative opportunities using this unique and versatile scientific instrument.

  4. Delayed flap coverage of open extremity fractures after previous vacuum-assisted closure (VAC) therapy - worse or worth?

    Science.gov (United States)

    Steiert, Andreas E; Gohritz, Andreas; Schreiber, Thomas C; Krettek, Christian; Vogt, Peter M

    2009-05-01

    Controversy remains regarding timing in the management of complex traumatic lower extremity defects. Many authors recommend a definitive bony and soft tissue reconstruction within a critical period of 72 h, yet in many patients this may be impossible due to concomitant injuries or delayed referral. However, little data are available on the results of delayed flap reconstruction of complex traumatic extremity defects, especially using new technologies of wound coverage such as vacuum-assisted closure (VAC((R))) therapy which may reduce the disadvantages of conventional open wound therapy prior to a subsequent flap reconstruction. We retrospectively analysed the soft tissue reconstructions in 43 open extremity fractures during a 4-year period with special regard to complications, overall flap loss and wound infection. A total of 29 male and 13 female patients with 33 open fractures of the lower and 10 of the upper extremity were included. All patients had been referred from a trauma centre at a mean interval of 19 days (range 1-96 days) after the trauma event with temporary VAC((R)) of their wounds after initial fracture fixation and initial debridement of necrotic tissue. Flap reconstruction was thus only possible later than 72 h and definitive wound closure was achieved at a mean time of 28 days (range 3-106 days). Overall, three pedicled flaps were lost and one of 38 microsurgical free flaps (2.6%) underwent necrosis, the cause of which was unrelated to treatment delay. According to this study, the flap reconstructions performed beyond the frequently quoted critical interval yielded similar results to those of immediate reconstruction within the first 3 days, as reported in the literature. This strategy is in accordance with the principles of 'Damage Control Orthopaedics (DCO)' and may reduce the importance of emergency reconstructions, especially in poly-traumatised patients.

  5. An electrostatic ion pump with nanostructured Si field emission electron source and Ti particle collectors for supporting an ultra-high vacuum in miniaturized atom interferometry systems

    International Nuclear Information System (INIS)

    Basu, Anirban; Velásquez-García, Luis F

    2016-01-01

    We report a field emission-based, magnetic-less ion pump architecture for helping maintain a high vacuum within a small chamber that is compatible with miniaturized cold-atom interferometry systems. A nanostructured silicon field emitter array, with each nano-sharp tip surrounded by a self-aligned proximal gate electrode, is used to generate a surplus of electrons that cause impact ionization of gas molecules. A two-stage cylindrical electron collector, made of titanium, is used to increase the travel distance of the electrons, augmenting the ionization probability; gas ionization is subsequently followed by gettering of the ions by a negatively charged, annular-shaped titanium electrode. A proof-of-concept pump prototype was characterized using a 25 cm 3 stainless steel vacuum chamber backed up by an external turbomolecular pump, a diaphragm pump, and a standard ion pump. Pumping action was observed with the electrostatic pump operating alone after an initial rapid rise of the chamber pressure due to electron/ion scrubbing. In addition, running the electrostatic pump in combination with the standard ion pump results in a lower vacuum level compared to the vacuum level produced by the standard ion pump acting alone. A proposed reduced-order model accurately predicts the functional dependence of the pressure versus time data and provides a good estimate of the characteristic pumping time constant inferred from the experiments. (paper)

  6. Vacuum mechatronics first international workshop

    Energy Technology Data Exchange (ETDEWEB)

    Belinski, S.E.; Shirazi, M.; Hackwood, S.; Beni, G. (eds.) (California Univ., Santa Barbara, CA (USA))

    1989-01-01

    This report contains papers on the following topics: proposed epitaxial thin film growth in the ultra-vacuum of space; particle monitoring and control in vacuum processing equipment; electrostatic dust collector for use in vacuum systems; materials evaluation of an electrically noisy vacuum slip ring assembly; an overview of lubrication and associated materials for vacuum service; the usage of lubricants in a vacuum environment; guidelines and practical applications for lubrication in vacuum; recent development in leak detector and calibrator designs; the durability of ballscrews for ultrahigh vacuum; vacuum-compatible robot for self-contained manufacturing systems; the design, fabrication, and assembly of an advanced vacuum robotics system for space payload calibration; design criteria for mechanisms used in space; and concepts and requirements for semiconductor multiprocess integration in vacuum. These papers are indexed separately elsewhere.

  7. Ultra high vacuum technology

    CERN Multimedia

    CERN. Geneva

    2001-01-01

    A short introduction for some basic facts and equations. Subsquently, discussion about: Building blocks of an ultrahigh vacuum system - Various types of pumps required to reach uhv and methods to reduce these effects - Outgassing phenomena induced by the presence of a particle beam and the most common methods to reduce these effects It will be given some practical examples from existing CERN accelerators and discuss the novel features of the future LHC vacuum system.

  8. Preparation of hydrosol suspensions of elemental and core–shell nanoparticles by co-deposition with water vapour from the gas-phase in ultra-high vacuum conditions

    International Nuclear Information System (INIS)

    Binns, Chris; Prieto, Pilar; Baker, Stephen; Howes, Paul; Dondi, Ruggero; Burley, Glenn; Lari, Leonardo; Kröger, Roland; Pratt, Andrew; Aktas, Sitki; Mellon, John K.

    2012-01-01

    We report a new method to produce liquid suspensions of nanoparticles by co-deposition with water vapour from the gas-phase in ultra-high vacuum (UHV) conditions. The water is injected from outside the vacuum as a molecular beam onto a substrate maintained at 77 K and forms an ice layer with a UHV vapour pressure. Molecular dynamics simulations confirm that the nanoparticles are soft-landed close to the surface of the growing ice layer. We show that the un-agglomerated size distribution within the liquid is similar to the gas-phase size distribution and demonstrate that the inclusion of surfactants in the injected water prevents agglomeration. The method allows the flexibility and tight size control available with gas-phase production methods to be applied to making nanoparticle suspensions with any desired properties. This is important for practical applications, especially in medicine. We have extended the method to include core–shell nanoparticles, in which there is flexible control over the core size and shell thickness and free choice of the material in either. Here, we report the production of suspensions of Cu, Ag and Au elemental nanoparticles and Fe-Au and Fe-Fe-oxide core–shell nanoparticles with diameters in the range 5–15 nm. We demonstrate the power of the method in practical applications in the case of Fe-Fe-oxide nanoparticles, which have a specific absorption rate of an applied oscillating magnetic field that is significantly higher than available Fe-oxide nanoparticle suspensions and the highest yet reported. These will thus have a very high-performance in the treatment of tumours by magnetic nanoparticle hyperthermia.

  9. Conceptual design and application studies of piezoelectric crystal motors under ultra-high vacuum conditions; Konzepterstellung und Verwendungsmoeglichkeiten eines Piezokristallmotors im Ultrahochvakuum

    Energy Technology Data Exchange (ETDEWEB)

    Nagler, Jens

    2009-08-15

    For the operation of accelerators it is important that motions in the vacuum occur. The here produced diploma thesis deals with the possibility to perform thes motions with piezocrystal motors in order to abandon wear-susceptible membrane bellows. For this studies have been performed, which should show for which it is useful to apply a piezocrystal motor. Limits are shown, advances and disadvantages are weighted in the thesis. Construction with with subsequent test of a tandem facility and an outlook on possible future concepts form the main content. [German] Fuer den Betrieb von Beschleunigern ist es wichtig, dass Bewegungen im Vakuum stattfinden. Die hier angefertigte Diplomarbeit befasst sich mit der Moeglichkeit, diese Bewegungen mit Piezokristallmotoren durchzufuehren, um auf verschleissanfaellige Membranbaelge zu verzichten. Hierfuer sind Studien durchgefuehrt worden, die zeigen sollen, wofuer es ratsam ist, einen Piezokristallmotor zu verwenden. Grenzen werden aufgezeigt, Vor- und Nachteile werden in der Arbeit abgewogen. Konstruktion mit anschliessenden Tests eines Tandemaufbaus und ein Ausblick auf moegliche zukuenftige Konzepte bilden den Kerninhalt. (orig.)

  10. Scanning Tunneling Microscopy Study of Carbon Tetrachloride Adsorption and Degradation on a Natural a-Fe2O3(0001) Surface in Ultrahigh Vacuum

    Science.gov (United States)

    Taeg Rim, Kwang; Fitts, Jeffrey; Adib, Kaveh; Camillone, Nicholas, III; Schlosser, Peter; Osgood, Richard, Jr.; Flynn, George; Joyce, Stephen

    2001-03-01

    Scanning tunneling microscopy and low energy electron diffraction have been used to study a natural a-Fe2O3(0001) surface and the adsorption and degradation of carbon tetrachloride on the reduced Fe3O4(111) terminated surface. A natural a-Fe2O3 (0001) surface was prepared by repeated cycles of Ar+ ion sputtering and annealing in vacuum or in O2 at 850 K. STM images and a LEED pattern indicate that an Fe3O4(111) terminated surface and a bi-phase can be formed depending on annealing conditions. The Fe3O4(111) terminated surface was dosed with CCl4 at room temperature, and flashed up to 590 K and 850 K. STM images show adsorbates on the surface at room temperature and the degradation products of CCl4 are isolated on the surface as the flashing temperature increases up to 850 K. Results from a companion temperature programmed desorption investigation are used in conjunction with the STM images to propose site specific reactions of CCl4 on the Fe3O4(111) terminated surface.

  11. Introduction to vacuum technology: supplementary study material developed for IVS sponsored vacuum courses

    International Nuclear Information System (INIS)

    Bhusan, K.G.

    2008-01-01

    Vacuum technology has advanced to a large extent mainly from the demands of experimental research scientists who have more than ever understood the need for clean very low pressure environments. This need only seems to increase as the lowest pressures achievable in a laboratory setup are dropping down by the decade. What is not usually said is that conventional techniques of producing ultrahigh vacuum have also undergone a metamorphosis in order to cater to the multitude of restrictions in modern day scientific research. This book aims to give that practical approach to vacuum technology. The basics are given in the first chapter with more of a definition oriented approach - which is practically useful. The second chapter deals with the production of vacuum and ultrahigh vacuum with an emphasis on the working principles of several pumps and their working pressure ranges. Measurement of low pressures, both total and partial is presented in the third chapter with a note on leak detection and mass spectrometric techniques. Chapter 4 gives an overview of the materials that are vacuum compatible and their material properties. Chapter 5 gives the necessary methods to be followed for cleaning of vacuum components especially critical if ultrahigh vacuum environment is required. The practical use of a ultrahigh vacuum environment is demonstrated in Chapter 6 for production of high quality thin films through vapour deposition

  12. Vacuum compatibility of 3D-printed materials

    OpenAIRE

    Povilus, AP; Wurden, CJ; Vendeiro, Z; Baquero-Ruiz, M; Fajans, J

    2014-01-01

    The fabrication fidelity and vacuum properties are tested for currently available 3D-printed materials including polyamide, glass, acrylic, and sterling silver. The silver was the only material found to be suitable to ultrahigh vacuum environments due to outgassing and sublimation observed in other materials. © 2014 American Vacuum Society.

  13. Indian Vacuum Society: The Indian Vacuum Society

    Science.gov (United States)

    Saha, T. K.

    2008-03-01

    The Indian Vacuum Society (IVS) was established in 1970. It has over 800 members including many from Industry and R & D Institutions spread throughout India. The society has an active chapter at Kolkata. The society was formed with the main aim to promote, encourage and develop the growth of Vacuum Science, Techniques and Applications in India. In order to achieve this aim it has conducted a number of short term courses at graduate and technician levels on vacuum science and technology on topics ranging from low vacuum to ultrahigh vacuum So far it has conducted 39 such courses at different parts of the country and imparted training to more than 1200 persons in the field. Some of these courses were in-plant training courses conducted on the premises of the establishment and designed to take care of the special needs of the establishment. IVS also regularly conducts national and international seminars and symposia on vacuum science and technology with special emphasis on some theme related to applications of vacuum. A large number of delegates from all over India take part in the deliberations of such seminars and symposia and present their work. IVS also arranges technical visits to different industries and research institutes. The society also helped in the UNESCO sponsored post-graduate level courses in vacuum science, technology and applications conducted by Mumbai University. The society has also designed a certificate and diploma course for graduate level students studying vacuum science and technology and has submitted a syllabus to the academic council of the University of Mumbai for their approval, we hope that some colleges affiliated to the university will start this course from the coming academic year. IVS extended its support in standardizing many of the vacuum instruments and played a vital role in helping to set up a Regional Testing Centre along with BARC. As part of the development of vacuum education, the society arranges the participation of

  14. Vacuum Technology

    Energy Technology Data Exchange (ETDEWEB)

    Biltoft, P J

    2004-10-15

    The environmental condition called vacuum is created any time the pressure of a gas is reduced compared to atmospheric pressure. On earth we typically create a vacuum by connecting a pump capable of moving gas to a relatively leak free vessel. Through operation of the gas pump the number of gas molecules per unit volume is decreased within the vessel. As soon as one creates a vacuum natural forces (in this case entropy) work to restore equilibrium pressure; the practical effect of this is that gas molecules attempt to enter the evacuated space by any means possible. It is useful to think of vacuum in terms of a gas at a pressure below atmospheric pressure. In even the best vacuum vessels ever created there are approximately 3,500,000 molecules of gas per cubic meter of volume remaining inside the vessel. The lowest pressure environment known is in interstellar space where there are approximately four molecules of gas per cubic meter. Researchers are currently developing vacuum technology components (pumps, gauges, valves, etc.) using micro electro mechanical systems (MEMS) technology. Miniature vacuum components and systems will open the possibility for significant savings in energy cost and will open the doors to advances in electronics, manufacturing and semiconductor fabrication. In conclusion, an understanding of the basic principles of vacuum technology as presented in this summary is essential for the successful execution of all projects that involve vacuum technology. Using the principles described above, a practitioner of vacuum technology can design a vacuum system that will achieve the project requirements.

  15. Vacuum extraction

    DEFF Research Database (Denmark)

    Maagaard, Mathilde; Oestergaard, Jeanett; Johansen, Marianne

    2012-01-01

    Objectives. To develop and validate an Objective Structured Assessment of Technical Skills (OSATS) scale for vacuum extraction. Design. Two-part study design: Primarily, development of a procedure-specific checklist for vacuum extraction. Hereafter, validation of the developed OSATS scale for vac...

  16. Vacuum mechatronics

    Science.gov (United States)

    Hackwood, Susan; Belinski, Steven E.; Beni, Gerardo

    1989-01-01

    The discipline of vacuum mechatronics is defined as the design and development of vacuum-compatible computer-controlled mechanisms for manipulating, sensing and testing in a vacuum environment. The importance of vacuum mechatronics is growing with an increased application of vacuum in space studies and in manufacturing for material processing, medicine, microelectronics, emission studies, lyophylisation, freeze drying and packaging. The quickly developing field of vacuum mechatronics will also be the driving force for the realization of an advanced era of totally enclosed clean manufacturing cells. High technology manufacturing has increasingly demanding requirements for precision manipulation, in situ process monitoring and contamination-free environments. To remove the contamination problems associated with human workers, the tendency in many manufacturing processes is to move towards total automation. This will become a requirement in the near future for e.g., microelectronics manufacturing. Automation in ultra-clean manufacturing environments is evolving into the concept of self-contained and fully enclosed manufacturing. A Self Contained Automated Robotic Factory (SCARF) is being developed as a flexible research facility for totally enclosed manufacturing. The construction and successful operation of a SCARF will provide a novel, flexible, self-contained, clean, vacuum manufacturing environment. SCARF also requires very high reliability and intelligent control. The trends in vacuum mechatronics and some of the key research issues are reviewed.

  17. Cosmic vacuum

    International Nuclear Information System (INIS)

    Chernin, Artur D

    2001-01-01

    Recent observational studies of distant supernovae have suggested the existence of cosmic vacuum whose energy density exceeds the total density of all the other energy components in the Universe. The vacuum produces the field of antigravity that causes the cosmological expansion to accelerate. It is this accelerated expansion that has been discovered in the observations. The discovery of cosmic vacuum radically changes our current understanding of the present state of the Universe. It also poses new challenges to both cosmology and fundamental physics. Why is the density of vacuum what it is? Why do the densities of the cosmic energy components differ in exact value but agree in order of magnitude? On the other hand, the discovery made at large cosmological distances of hundreds and thousands Mpc provides new insights into the dynamics of the nearby Universe, the motions of galaxies in the local volume of 10 - 20 Mpc where the cosmological expansion was originally discovered. (reviews of topical problems)

  18. Cosmic vacuum

    Energy Technology Data Exchange (ETDEWEB)

    Chernin, Artur D [P.K. Shternberg State Astronomical Institute at the M.V. Lomonosov Moscow State University, Moscow (Russian Federation)

    2001-11-30

    Recent observational studies of distant supernovae have suggested the existence of cosmic vacuum whose energy density exceeds the total density of all the other energy components in the Universe. The vacuum produces the field of antigravity that causes the cosmological expansion to accelerate. It is this accelerated expansion that has been discovered in the observations. The discovery of cosmic vacuum radically changes our current understanding of the present state of the Universe. It also poses new challenges to both cosmology and fundamental physics. Why is the density of vacuum what it is? Why do the densities of the cosmic energy components differ in exact value but agree in order of magnitude? On the other hand, the discovery made at large cosmological distances of hundreds and thousands Mpc provides new insights into the dynamics of the nearby Universe, the motions of galaxies in the local volume of 10 - 20 Mpc where the cosmological expansion was originally discovered. (reviews of topical problems)

  19. Probing the vacuum with highly charged ions

    International Nuclear Information System (INIS)

    Bottcher, C.; Strayer, M.R.

    1987-01-01

    The physics of the Fermion vacuum is briefly described, and applied to pair production in heavy ion collisions. We consider in turn low energies (<50 MeV/nucleon), intermediate energies (<5 GeV/nucleon), and ultrahigh energies such as would be produced in a ring collider. At high energies, interesting questions of Lorentz and gauge invariance arise. Finally, some applications to the structure of high Z atoms are examined. 14 refs., 11 figs

  20. Vacuum strings in FRW models

    Energy Technology Data Exchange (ETDEWEB)

    Dyer, C C; Oattes, L M; Starkman, G D

    1988-01-01

    The authors find that vacuum string solutions cannot be embedded in an FRW model in the spirit of the swiss cheese model for inhomogeneities. Since all standard lensing calculations rely implicitly on the Swiss Cheese model, this result indicates that the previous lensing results for the vacuum string may be in error.

  1. Vacuum gauges

    International Nuclear Information System (INIS)

    Power, B.D.; Priestland, C.R.D.

    1978-01-01

    This invention relates to vacuum gauges, particularly of the type known as Penning gauges, which are cold cathode ionisation gauges, in which a magnetic field is used to lengthen the electron path and thereby increase the number of ions produced. (author)

  2. Magnons in ultrahigh vacuum deposited Fe/Ag multilayers

    International Nuclear Information System (INIS)

    El Kiadi, I.; Lassri, H.; Benkirane, K.; Bensassi, B.

    2007-01-01

    We have grown Fe/Ag multilayers with Ag buffer layer, by evaporation under UHV conditions on glass substrates. The magnetic properties of Fe/Ag multilayers are examined as a function of Fe layer thickness t Fe . The temperature dependence of the spontaneous magnetization M(T) is well described by a T 3/2 law in all multilayers. A spin-wave theory has been used to explain the temperature dependence of the magnetization and the approximate values for the bulk exchange interaction J b and surface exchange interaction J s for various Fe layer thicknesses have been obtained

  3. Bake-Out Mobile Controls for Large Vacuum Systems

    CERN Document Server

    Blanchard, S; Gomes, P; Pereira, H; Kopylov, L; Merker, S; Mikheev, M

    2014-01-01

    Large vacuum systems at CERN (Large Hadron Collider - LHC, Low Energy Ion Rings - LEIR...) require bake-out to achieve ultra-high vacuum specifications. The bake-out cycle is used to decrease the outgassing rate of the vacuum vessel and to activate the Non-Evaporable Getter (NEG) thin film. Bake-out control is a Proportional-Integral-Derivative (PID) regulation with complex recipes, interlocks and troubleshooting management and remote control. It is based on mobile Programmable Logic Controller (PLC) cabinets, fieldbus network and Supervisory Control and Data Acquisition (SCADA) application. The CERN vacuum installations include more than 7 km of baked vessels; using mobile cabinets reduces considerably the cost of the control system. The cabinets are installed close to the vacuum vessels during the time of the bake-out cycle. Mobile cabinets can be used in any of the CERN vacuum facilities. Remote control is provided through a fieldbus network and a SCADA application

  4. Processing and evaluation of the AGS Booster ultra-high vaccum system

    International Nuclear Information System (INIS)

    Hseuh, H.C.; Mapes, M.; Schnitzenbaumer, P.; Shen, B.; Sikora, R.; Stattel, P.

    1991-01-01

    The AGS Booster is a synchrotron for the acceleration of both protons and heavy ions. To minimize the beam loss due to charge exchange of the partially stripped, low Β very heavy ions with the residual gas molecules, pressure of low 10 -11 Torr is required for the 200 m booster ring. To achieve this ultra high vacuum, chemical cleaning, vacuum furnace degassing and insitu bake were employed for all chambers and beam components. Using these procedures, vacuums of low 10 -11 Torr have been routinely achieved during the testing of individual half cells and beam components, and during the commissioning of the vacuum sectors. In this paper, the design and layout of chambers, flanges and bakeout hardware is briefly described. The vacuum processing of different components and the results of bakeout and evaluation are summarized. The experience gained during the construction and commissioning of this ultra-high vacuum system is also given. 3 refs., 3 figs., 1 tab

  5. Construction of vacuum system for Tristan accumulation ring

    International Nuclear Information System (INIS)

    Ishimaru, H.; Horikoshi, G.; Kobayashi, M.; Kubo, T.; Mizuno, H.; Momose, T.; Narushima, K.; Watanabe, H.; Yamaguchi, H.

    1983-01-01

    An all aluminum-alloy vacuum system for the TRISTAN accumulation ring is now under construction. Aluminum and aluminum alloys are preferred materials for ultrahigh vacuum systems of large electron storage rings because of their good thermal conductivity, extremely low outgassing rate, and low residual radioactivity. Vacuum beam chambers for the dipole and quadrupole magnets are extruded using porthole dies. The aluminum alloy 6063-T6 provides superior performance in extrusion. For ultrahigh vacuum performance, a special extrusion technique is applied which, along with the outgassing procedure used, is described in detail. Aluminum alloy 3004 seamless elliptical bellows are inserted between the dipole and quadrupole magnet chambers. These bellows are produced by the hydraulic forming of a seamless tube. The seamless bellows and the beam chambers are joined by fully automatic welding. The ceramic chambers for the kicker magnets, the fast bump magnets, and the slow beam intensity monitor are inserted in the aluminum alloy beam chambers. The ceramic chamber (98% alumina) and elliptical bellows are brazed with brazing sheets (4003-3003-4003) in a vacuum furnace. The brazing technique is described. The inner surface of the ceramic chamber is coated with a TiMo alloy by vacuum evaporation to permit a smooth flow of the RF wall current. Other suitable aluminum alloy components, including fittings, feedthroughs, gauges, optical windows, sputter ion pumps, turbomolecular pumps, and valves have been developed; their fabrication is described

  6. Leybold vacuum handbook

    CERN Document Server

    Diels, K; Diels, Kurt

    1966-01-01

    Leybold Vacuum Handbook presents a collection of data sets that are essential for numerical calculation of vacuum plants and vacuum processes. The title first covers vacuum physics, which includes gas kinetics, flow phenomena, vacuum gauges, and vapor removal. Next, the selection presents data on vacuum, high vacuum process technology, and gas desorption and gettering. The text also deals with materials, vapor pressure, boiling and melting points, and gas permeability. The book will be of great interest to engineers and technicians that deals with vacuum related technologies.

  7. Design and construction of Alborz tokamak vacuum vessel system

    International Nuclear Information System (INIS)

    Mardani, M.; Amrollahi, R.; Koohestani, S.

    2012-01-01

    Highlights: ► The Alborz tokamak is a D-shape cross section tokamak that is under construction in Amirkabir University of Technology. ► As one of the key components for the device, the vacuum vessel can provide ultra-high vacuum and clean environment for the plasma operation. ► A limiter is a solid surface which defines the edge of the plasma and designed to protect the wall from the plasma, localizes the plasma–surface interaction and localizes the particle recycling. ► Structural analyses were confirmed by FEM model for dead weight, vacuum pressure and plasma disruptions loads. - Abstract: The Alborz tokamak is a D-shape cross section tokamak that is under construction in Amirkabir University of Technology. At the heart of the tokamak is the vacuum vessel and limiter which collectively are referred to as the vacuum vessel system. As one of the key components for the device, the vacuum vessel can provide ultra-high vacuum and clean environment for the plasma operation. The VV systems need upper and lower vertical ports, horizontal ports and oblique ports for diagnostics, vacuum pumping, gas puffing, and maintenance accesses. A limiter is a solid surface which defines the edge of the plasma and designed to protect the wall from the plasma, localizes the plasma–surface interaction and localizes the particle recycling. Basic structure analyses were confirmed by FEM model for dead weight, vacuum pressure and plasma disruptions loads. Stresses at general part of the VV body are lower than the structure material allowable stress (117 MPa) and this analysis show that the maximum stresses occur near the gravity support, and is about 98 MPa.

  8. Vacuum Technology in the study of Graphene

    International Nuclear Information System (INIS)

    Ghoshal, A K; Banerjee, S N; Chakraborty, D

    2012-01-01

    Graphene, an allotrope of carbon is a two-dimensional sheet of covalently bonded carbon atoms that has been attracting great attention in the field of electronics. In a recent review graphene is defined as a flat monolayer of carbon atoms tightly packed into a 2-D honeycomb lattice. A survey has been made of the production processes and instrumentation for characterization of graphene. In the production of graphene, the methods mainly used are Epitaxial growth, oxide reduction, growth from metal-carbon melts, growth from sugar. In the characterization of graphene, the instruments that are mainly used to study the atomic properties, electronic properties, optical properties, spin properties are Scanning Electron Microscopy, Transmission Electron Microscopy, Raman Spectroscopy. In all these instruments high or ultra-high vacuum is required. This paper attempts to correlate vacuum technology in the production and characterization of graphene.

  9. MEA vacuum system

    International Nuclear Information System (INIS)

    Stroo, R.; Schwebke, H.; Heine, E.

    1984-01-01

    This report describes construction and operation of the MEA vacuum system of NIKHEF (Netherlands). First, the klystron vacuum system, beam transport system, diode pump and a triode pump are described. Next, the isolation valve and the fast valves of the vacuum system are considered. Measuring instruments, vacuum system commands and messages of failures are treated in the last chapter. (G.J.P.)

  10. Vacuum system for ISABELLE

    International Nuclear Information System (INIS)

    Hobson, J.P.

    1975-01-01

    An analysis is presented of the proposed vacuum system for the planned ISABELLE storage rings with respect to acceptability and practicality from the vacuum viewport. A comparison is made between the proposed vacuum system and the vacuum system at the CERN ISR, and some comments on various design and operational parameters are made

  11. Note: Ultra-low birefringence dodecagonal vacuum glass cell

    Energy Technology Data Exchange (ETDEWEB)

    Brakhane, Stefan, E-mail: brakhane@iap.uni-bonn.de; Alt, Wolfgang; Meschede, Dieter; Robens, Carsten; Moon, Geol; Alberti, Andrea [Institut für Angewandte Physik, Universität Bonn, Wegelerstr. 8, D-53115 Bonn (Germany)

    2015-12-15

    We report on an ultra-low birefringence dodecagonal glass cell for ultra-high vacuum applications. The epoxy-bonded trapezoidal windows of the cell are made of SF57 glass, which exhibits a very low stress-induced birefringence. We characterize the birefringence Δn of each window with the cell under vacuum conditions, obtaining values around 10{sup −8}. After baking the cell at 150 °C, we reach a pressure below 10{sup −10} mbar. In addition, each window is antireflection coated on both sides, which is highly desirable for quantum optics experiments and precision measurements.

  12. Vacuum system for the tokamak fusion test reactor (TFTR)

    International Nuclear Information System (INIS)

    Lange, W.J.; Green, D.; Sink, D.A.

    1976-01-01

    The vacuum system for TFTR is described. Insofar as possible, conventional and ultrahigh vacuum (UHV) components and technology will be employed. Subassemblies will be prebaked in vacuum to reduce subsequent outgassing, and assembly will employ TIG welding and metal gaskets. It is not anticipated that the totally assembled torus with its numerous diagnostic appendages will be baked in situ to a high temperature, however a lower bakeout temperature (approximately 250 0 C) is under consideration. Final vacuum conditioning will be performed using discharge cleaning to obtain a specific outgassing rate of less than or = to 10 -10 Torr liter/sec cm 2 hydrogen isotopes and less than or = to 10 -12 Torr liter/sec cm 2 of other gases, and a base pressure of less than or = to 5 x 10 -8 Torr

  13. The vacuum interlock system for the CELSIUS ring

    International Nuclear Information System (INIS)

    Gajewski, K.

    1990-01-01

    A vacuum interlock system has been designed and built for the CELSIUS storage ring. The ultrahigh-vacuum system of CELSIUS has a design pressure of 10 -11 mbar. This is achieved by using vacuum-fired stainless-steel chambers, baking the whole ring to 300degC and running some 50 sputter ion and titanium sublimation pumps. The turbopumps, combined with roughing pumps, are used during the pump-down and the bake-out. The pressure is monitored by Penning vacuum gauges. There is a number of programmable pressure thresholds set to trigger various events (like closing the sector valves, disabling the bake-out, etc.). The interlock system is based on the Mitsubishi programmable logic controller (PLC). An IBM PC is used as an operator's console. The operation and performance of the system is described. On the basis of present experience an upgrading of the system is suggested. (orig.)

  14. Proceedings of the international conference on vacuum science and technology and SRS vacuum systems. V.1: accelerators and SRS systems

    International Nuclear Information System (INIS)

    Venkatramani, N.; Sinha, A.K.

    1995-01-01

    An International Conference on Vacuum Science and Technology, INCOVAST-95 was held during January 30 - February 2, 1995 at the Centre for Advanced Technology (CAT), Indore under the aegis of the Indian Vacuum Society. Centre for Advanced Technology has a major programme of design and construction of a 450 MeV electron storage ring, synchrotron radiation source Indus-1 followed by the 1.25 GeV Indus-2. To match the activities at the centre, the present conference had ultrahigh vacuum for Synchrotron Radiation Sources (SRSs) as the main theme. Three major topics, namely accelerators and SRS systems, thin films and surfaces, vacuum components and applications were covered in detail. A short summary of the discussions is also included in the proceedings. Papers relevant to INIS are indexed separately

  15. Vacuum Simulations in High Energy Accelerators and Distribution Properties of Continuous and Discrete Particle Motions

    OpenAIRE

    Aichinger, Ida; Larcher, Gerhard; Kersevan, Roberto

    2017-01-01

    The underlying thesis on mathematical simulation methods in application and theory is structured into three parts. The first part sets up a mathematical model capable of predicting the performance and operation of an accelerator’s vacuum system based on analytical methods. A coupled species-balance equation system describes the distribution of the gas dynamics in an ultra-high vacuum system considering impacts of conductance limitations, beam induced effects (ion-, electron-, and photon-induc...

  16. Evaluating strength at ultra-high temperatures-Methods and results

    International Nuclear Information System (INIS)

    Voelkl, Rainer; Fischer, Bernd; Beschliesser, Manuel; Glatzel, Uwe

    2008-01-01

    Proprietary equipment for mechanical testing at ultra-high temperatures by ohmic heating is outlined. Strain is measured with a video extensometer with an accuracy of up to Δε-bar∼±0.00025%. Stability and accuracy of the test system are evaluated on Pt- and refractory alloys. These specially designed and built test facilities are compared to commercially available high-vacuum test chambers with tungsten heater

  17. Cold vacuum drying facility design requirements

    Energy Technology Data Exchange (ETDEWEB)

    Irwin, J.J.

    1997-09-24

    This release of the Design Requirements Document is a complete restructuring and rewrite to the document previously prepared and released for project W-441 to record the design basis for the design of the Cold Vacuum Drying Facility.

  18. Cold vacuum drying facility design requirements

    International Nuclear Information System (INIS)

    Irwin, J.J.

    1997-01-01

    This release of the Design Requirements Document is a complete restructuring and rewrite to the document previously prepared and released for project W-441 to record the design basis for the design of the Cold Vacuum Drying Facility

  19. Vacuum-assisted delivery

    Science.gov (United States)

    ... medlineplus.gov/ency/patientinstructions/000514.htm Vacuum-assisted delivery To use the sharing features on this page, ... through the birth canal. When is Vacuum-assisted Delivery Needed? Even after your cervix is fully dilated ( ...

  20. Improved anchoring of SSS with vacuum barrier to avoid displacement

    CERN Document Server

    Capatina, O; Foreste, A; Parma, V; Renaglia, T; Quesnel, J

    2009-01-01

    As presented in the previous speech, the incident in sector 3-4 of the LHC caused a high pressure build-up inside the cryostat insulation vacuum resulting in high longitudinal forces acting on the insulation vacuum barriers. This resulted in braking floor and floor fixations of the SSS with vacuum barrier. The strategy of improving anchoring of SSS with vacuum barrier to avoid displacement is presented and discussed.

  1. Vacuum system of SST-1 Tokamak

    International Nuclear Information System (INIS)

    Khan, Ziauddin; Pathan, Firozkhan; George, Siju; Semwal, Pratibha; Dhanani, Kalpesh; Paravastu, Yuvakiran; Thankey, Prashant; Ramesh, Gattu; Himabindu, Manthena; Pradhan, Subrata

    2013-01-01

    Highlights: ► Air leaks developed during ongoing SST-1 cooldown campaign were detected online using RGA. ► The presence of N 2 and O 2 gases with the ratio of their partial pressures with ∼3.81:1 confirmed the air leaks. ► Baking of SST-1 was done efficiently by flowing hot N 2 gas in C-channels welded on inner surfaces without any problem. ► In-house fabricated demountable bull nose couplers were demonstrated for high temperature and pressure applications. ► Cryopumping effect was observed when liquid helium cooled superconducting magnets reached below 63 K. -- Abstract: Vacuum chambers of Steady State Superconducting (SST-1) Tokamak comprises of the vacuum vessel and the cryostat. The plasma will be confined inside the vacuum vessel while the cryostat houses the superconducting magnet systems (TF and PF coils), LN 2 cooled thermal shields and hydraulics for these circuits. The vacuum vessel is an ultra-high (UHV) vacuum chamber while the cryostat is a high-vacuum (HV) chamber. In order to achieve UHV inside the vacuum vessel, it would be baked at 150 °C for longer duration. For this purpose, U-shaped baking channels are welded inside the vacuum vessel. The baking will be carried out by flowing hot nitrogen gas through these channels at 250 °C at 4.5 bar gauge pressure. During plasma operation, the pressure inside the vacuum vessel will be raised between 1.0 × 10 −4 mbar and 1.0 × 10 −5 mbar using piezoelectric valves and control system. An ultimate pressure of 4.78 × 10 −6 mbar is achieved inside the vacuum vessel after 100 h of pumping. The limitation is due to the development of few leaks of the order of 10 −5 mbar l/s at the critical locations of the vacuum vessel during baking which was confirmed with the presence of nitrogen gas and oxygen gas with the ratio of ∼3.81:1 indicating air leak. Similarly an ultimate vacuum of 2.24 × 10 −5 mbar is achieved inside the cryostat. Baking of the vacuum vessel up to 110 °C with ±10

  2. Vacuum system of SST-1 Tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Ziauddin, E-mail: ziauddin@ipr.res.in [Institute for Plasma Research, Near Indira Bridge, Bhat, Gandhinagar 382 428 (India); Pathan, Firozkhan; George, Siju; Semwal, Pratibha; Dhanani, Kalpesh; Paravastu, Yuvakiran; Thankey, Prashant; Ramesh, Gattu; Himabindu, Manthena; Pradhan, Subrata [Institute for Plasma Research, Near Indira Bridge, Bhat, Gandhinagar 382 428 (India)

    2013-10-15

    Highlights: ► Air leaks developed during ongoing SST-1 cooldown campaign were detected online using RGA. ► The presence of N{sub 2} and O{sub 2} gases with the ratio of their partial pressures with ∼3.81:1 confirmed the air leaks. ► Baking of SST-1 was done efficiently by flowing hot N{sub 2} gas in C-channels welded on inner surfaces without any problem. ► In-house fabricated demountable bull nose couplers were demonstrated for high temperature and pressure applications. ► Cryopumping effect was observed when liquid helium cooled superconducting magnets reached below 63 K. -- Abstract: Vacuum chambers of Steady State Superconducting (SST-1) Tokamak comprises of the vacuum vessel and the cryostat. The plasma will be confined inside the vacuum vessel while the cryostat houses the superconducting magnet systems (TF and PF coils), LN{sub 2} cooled thermal shields and hydraulics for these circuits. The vacuum vessel is an ultra-high (UHV) vacuum chamber while the cryostat is a high-vacuum (HV) chamber. In order to achieve UHV inside the vacuum vessel, it would be baked at 150 °C for longer duration. For this purpose, U-shaped baking channels are welded inside the vacuum vessel. The baking will be carried out by flowing hot nitrogen gas through these channels at 250 °C at 4.5 bar gauge pressure. During plasma operation, the pressure inside the vacuum vessel will be raised between 1.0 × 10{sup −4} mbar and 1.0 × 10{sup −5} mbar using piezoelectric valves and control system. An ultimate pressure of 4.78 × 10{sup −6} mbar is achieved inside the vacuum vessel after 100 h of pumping. The limitation is due to the development of few leaks of the order of 10{sup −5} mbar l/s at the critical locations of the vacuum vessel during baking which was confirmed with the presence of nitrogen gas and oxygen gas with the ratio of ∼3.81:1 indicating air leak. Similarly an ultimate vacuum of 2.24 × 10{sup −5} mbar is achieved inside the cryostat. Baking of the

  3. Ultrahigh temperature intermetallic alloys

    Energy Technology Data Exchange (ETDEWEB)

    Brady, M.P.; Zhu, J.H.; Liu, C.T.; Tortorelli, P.F.; Wright, J.L.; Carmichael, C.A.; Walker, L.R. [Oak Ridge National Lab., TN (United States). Metals and Ceramics Div.

    1997-12-01

    A new family of Cr-Cr{sub 2}X based alloys with fabricability, mechanical properties, and oxidation resistance superior to previously developed Cr-Cr{sub 2}Nb and Cr-Cr{sub 2}Zr based alloys has been identified. The new alloys can be arc-melted/cast without cracking, and exhibit excellent room temperature and high-temperature tensile strengths. Preliminary evaluation of oxidation behavior at 1100 C in air indicates that the new Cr-Cr{sub 2}X based alloys form an adherent chromia-based scale. Under similar conditions, Cr-Cr{sub 2}Nb and Cr-Cr{sub 2}Zr based alloys suffer from extensive scale spallation.

  4. Development and Measurement of Strain Free RF Photoinjector Vacuum Windows

    CERN Document Server

    Biedron, Sandra G

    2004-01-01

    RF photoinjectors produce the highest brightness electron bunches only under nearly ideal illumination by a drive laser. The vacuum window used to introduce the laser beam is an essential element that may potentially degrade any distribution, making it difficult or impossible to know the actual uniformity achieved at the cathode. Because of the necessity to obtain ultrahigh vacuum near the photoinjector, some restrictions are imposed on the fabrication technology available to manufacture distortion-free windows. At the UV wavelengths commonly used for photoinjectors, it is challenging to measure and eliminate degradation caused by vacuum windows. Here, we discuss the initial laser-based measurements of a strain-free, coated, UHV window manufactured by Insulator Seal in collaboration with members of Brookhaven and Argonne National Laboratories.

  5. Note: Hollow cathode lamp with integral, high optical efficiency isolation valve: A modular vacuum ultraviolet source

    International Nuclear Information System (INIS)

    Sloan Roberts, F.; Anderson, Scott L.

    2013-01-01

    The design and operating conditions of a hollow cathode discharge lamp for the generation of vacuum ultraviolet radiation, suitable for ultrahigh vacuum (UHV) application, are described in detail. The design is easily constructed, and modular, allowing it to be adapted to different experimental requirements. A thin isolation valve is built into one of the differential pumping stages, isolating the discharge section from the UHV section, both for vacuum safety and to allow lamp maintenance without venting the UHV chamber. The lamp has been used both for ultraviolet photoelectron spectroscopy of surfaces and as a “soft” photoionization source for gas-phase mass spectrometry

  6. Note: Hollow cathode lamp with integral, high optical efficiency isolation valve: A modular vacuum ultraviolet source

    Energy Technology Data Exchange (ETDEWEB)

    Sloan Roberts, F.; Anderson, Scott L. [Department of Chemistry, University of Utah, 315 S. 1400 E., Salt Lake City, Utah 84112 (United States)

    2013-12-15

    The design and operating conditions of a hollow cathode discharge lamp for the generation of vacuum ultraviolet radiation, suitable for ultrahigh vacuum (UHV) application, are described in detail. The design is easily constructed, and modular, allowing it to be adapted to different experimental requirements. A thin isolation valve is built into one of the differential pumping stages, isolating the discharge section from the UHV section, both for vacuum safety and to allow lamp maintenance without venting the UHV chamber. The lamp has been used both for ultraviolet photoelectron spectroscopy of surfaces and as a “soft” photoionization source for gas-phase mass spectrometry.

  7. Note: Hollow cathode lamp with integral, high optical efficiency isolation valve: a modular vacuum ultraviolet source.

    Science.gov (United States)

    Roberts, F Sloan; Anderson, Scott L

    2013-12-01

    The design and operating conditions of a hollow cathode discharge lamp for the generation of vacuum ultraviolet radiation, suitable for ultrahigh vacuum (UHV) application, are described in detail. The design is easily constructed, and modular, allowing it to be adapted to different experimental requirements. A thin isolation valve is built into one of the differential pumping stages, isolating the discharge section from the UHV section, both for vacuum safety and to allow lamp maintenance without venting the UHV chamber. The lamp has been used both for ultraviolet photoelectron spectroscopy of surfaces and as a "soft" photoionization source for gas-phase mass spectrometry.

  8. Rolling contact fatigue in a vacuum test equipment and coating analysis

    CERN Document Server

    Danyluk, Michael

    2014-01-01

    This book deals with wear and performance testing of thin solid film lubrication and hard coatings in an ultra-high vacuum (UHV), a process which enables rapid accumulation of stress cycles compared with testing in oil at atmospheric pressure. The authors' lucid and authoritative narrative broadens readers' understanding of the benefits of UHV testing: a cleaner, shorter test is achieved in high vacuum, disturbance rejection by the deposition controller may be optimized for maximum fatigue life of the coating using rolling contact fatigue testing (RCF) in a high vacuum, and RCF testing in UHV

  9. Magnetically induced vacuum decay

    International Nuclear Information System (INIS)

    Xue Shesheng

    2003-01-01

    We study the fermionic vacuum energy of vacua with and without application of an external magnetic field. The energetic difference of two vacua leads to the vacuum decaying and the vacuum energy being released. In the context of quantum field theories, we discuss why and how the vacuum energy can be released by spontaneous photon emission and/or paramagnetically screening the external magnetic field. In addition, we quantitatively compute the vacuum energy released, the paramagnetic screening effect, and the rate and spectrum of spontaneous photon emission. The possibilities of experimentally detecting such an effect of vacuum-energy release and that this effect accounts for the anomalous x-ray pulsar are discussed

  10. Vacuum technology Practice for scientific instruments

    CERN Document Server

    Yoshimura, Nagamitsu

    2008-01-01

    Nanotechnology has reached a level where almost every new development and even every new product uses features of nanoscopic properties of materials. As a consequence, an enormous amount of scientific instruments is used in order to synthesize and analyze new structures and materials. Due to the surface sensitivity of such materials, many of these instruments require ultrahigh vacuum that has to be provided under extreme conditions like very high voltages. In this book, Yoshimura provides a review of the UHV related development during the last decades. His very broad experience in the design enables him to present us this detailed reference. After a general description how to design UHV systems, he covers all important issue in detail, like pumps, outgasing, Gauges, and Electrodes for high voltages. Thus, this book serves as reference for everybody using UVH in his scientific equipment

  11. Vacuum vessel for the tandem Mirror Fusion Test Facility

    International Nuclear Information System (INIS)

    Gerich, J.W.

    1986-01-01

    In 1980, the US Department of Energy gave the Lawrence Livermore National Laboratory approval to design and build a tandem Mirror Fusion Test Facility (MFTF-B) to support the goals of the National Mirror Program. We designed the MFTF-B vacuum vessel both to maintain the required ultrahigh vacuum environment and to structurally support the 42 superconducting magnets plus auxiliary internal and external equipment. During our design work, we made extensive use of both simple and complex computer models to arrive at a cost-effective final configuration. As part of this work, we conducted a unique dynamic analysis to study the interaction of the 32,000-tonne concrete-shielding vault with the 2850-tonne vacuum vessel system. To maintain a vacuum of 2 x 10 -8 torr during the physics experiments inside the vessel, we designed a vacuum pumping system of enormous capacity. The vacuum vessel (4200-m 3 internal volume) has been fabricated and erected, and acceptance tests have been completed at the Livermore site. The rest of the machine has been assembled, and individual systems have been successfully checked. On October 1, 1985, we began a series of integrated engineering tests to verify the operation of all components as a complete system

  12. Gravitation and vacuum field

    International Nuclear Information System (INIS)

    Tevikyan, R.V.

    1986-01-01

    This paper presents equations that describe particles with spins s = 0, 1/2, 1 completely and which also describe 2s + 2 limiting fields as E → ∞. It is shown that the ordinary Hilbert-Einstein action for the gravitation field must be augmented by the action for the Bose vacuum field. This means that one must introduce in the gravitational equations a cosmological term proportional to the square of the strength of the Bose vacuum field. It is shown that the theory of gravitation describes three realities: matter, field, and vacuum field. A new form of matter--the vacuum field--is introduced into field theory

  13. Insulation vacuum and beam vacuum overpressure release

    CERN Document Server

    Parma, V

    2009-01-01

    There is evidence that the incident of 19th September caused a high pressure build-up inside the cryostat insulation vacuum which the existing overpressure devices could not contain. As a result, high longitudinal forces acting on the insulation vacuum barriers developed and broke the floor and the floor fixations of the SSS with vacuum barriers. The consequent large longitudinal displacements of the SSS damaged chains of adjacent dipole cryo-magnets. Estimates of the helium mass flow and the pressure build- up experienced in the incident are presented together with the pressure build-up for an even more hazardous event, the Maximum Credible Incident (MCI). The strategy of limiting the maximum pressure by the installation of addition pressure relieve devices is presented and discussed. Both beam vacuum lines were ruptured during the incident in sector 3-4 giving rise to both mechanical damage and pollution of the system. The sequence, causes and effects of this damage will be briefly reviewed. We will then an...

  14. Improving the Bevatron vacuum to 10-10 torr

    International Nuclear Information System (INIS)

    Avery, R.; Elioff, T.; Grunder, H.

    1981-03-01

    Pressure of approx. 10 -10 torr is needed in the Bevatron to accelerate partially-stripped very-heavy ions (e.g. U 69+ ) in the Bevatron without significant loss due to interactions with the residual gas. This ultra-high vacuum will be achieved by installing (summer and fall 1981) a cryogenic liner, mostly 12 0 K, surrounding the Bevatron circulating beam. The novel construction features are presented along with results from successful tests of prototype sections. This is believed to be the largest application of cryogenic pumping to particle accelerators yet undertaken

  15. Modern vacuum physics

    CERN Document Server

    Chambers, Austin

    2005-01-01

    Modern Vacuum Physics presents the principles and practices of vacuum science and technology along with a number of applications in research and industrial production. The first half of the book builds a foundation in gases and vapors under rarefied conditions, The second half presents examples of the analysis of representative systems and describes some of the exciting developments in which vacuum plays an important role. The final chapter addresses practical matters, such as materials, components, and leak detection. Throughout the book, the author''s explanations are presented in terms of first principles and basic physics, augmented by illustrative worked examples and numerous figures.

  16. Evaporation under vacuum condition

    International Nuclear Information System (INIS)

    Mizuta, Satoshi; Shibata, Yuki; Yuki, Kazuhisa; Hashizume, Hidetoshi; Toda, Saburo; Takase, Kazuyuki; Akimoto, Hajime

    2000-01-01

    In nuclear fusion reactor design, an event of water coolant ingress into its vacuum vessel is now being considered as one of the most probable accidents. In this report, the evaporation under vacuum condition is evaluated by using the evaporation model we have developed. The results show that shock-wave by the evaporation occurs whose behavior strongly depends on the initial conditions of vacuum. And in the case of lower initial pressure and temperature, the surface temp finally becomes higher than other conditions. (author)

  17. Ultrahigh piezoelectricity in ferroelectric ceramics by design

    Science.gov (United States)

    Li, Fei; Lin, Dabin; Chen, Zibin; Cheng, Zhenxiang; Wang, Jianli; Li, ChunChun; Xu, Zhuo; Huang, Qianwei; Liao, Xiaozhou; Chen, Long-Qing; Shrout, Thomas R.; Zhang, Shujun

    2018-03-01

    Piezoelectric materials, which respond mechanically to applied electric field and vice versa, are essential for electromechanical transducers. Previous theoretical analyses have shown that high piezoelectricity in perovskite oxides is associated with a flat thermodynamic energy landscape connecting two or more ferroelectric phases. Here, guided by phenomenological theories and phase-field simulations, we propose an alternative design strategy to commonly used morphotropic phase boundaries to further flatten the energy landscape, by judiciously introducing local structural heterogeneity to manipulate interfacial energies (that is, extra interaction energies, such as electrostatic and elastic energies associated with the interfaces). To validate this, we synthesize rare-earth-doped Pb(Mg1/3Nb2/3)O3-PbTiO3 (PMN-PT), as rare-earth dopants tend to change the local structure of Pb-based perovskite ferroelectrics. We achieve ultrahigh piezoelectric coefficients d33 of up to 1,500 pC N-1 and dielectric permittivity ɛ33/ɛ0 above 13,000 in a Sm-doped PMN-PT ceramic with a Curie temperature of 89 °C. Our research provides a new paradigm for designing material properties through engineering local structural heterogeneity, expected to benefit a wide range of functional materials.

  18. Continuous vacuum processing system for quartz crystal resonators

    International Nuclear Information System (INIS)

    Ney, R.J.; Hafner, E.

    1979-01-01

    An ultrahigh vacuum continuous cycle quartz crystal fabrication facility has been developed that assures an essentially contamination-free environment throughout the final manufacturing steps of the crystal unit. The system consists of five essentially tubular vacuum chambers that are interconnected through gate valves. The unplated crystal resonators, mounted in ceramic flatback frames and loaded on carrier trays, enter the vacuum system through an entrance air lock, are UV/ozone cleaned, baked at 300 0 C, plated to frequency, thermocompression sealed, and exit as completed crystal units through an exit air lock, while the bake, plate and seal chambers remain under continuous vacuum permanently. In-line conveyor belts are used, in conjunction with balanced vacuum manipulators, to move the resonator components to the various work stations. Unique high density, highly directional nozzle beam evaporation sources, capable of long term operation without reloading, are used for electroding the resonators simultaneously on both sides. The design goal for the system is a production rate of 200 units per 8 hour day; it is adaptable to automatic operation

  19. Helical type vacuum container

    International Nuclear Information System (INIS)

    Owada, Kimio.

    1989-01-01

    Helical type vacuum containers in the prior art lack in considerations for thermal expansion stresses to helical coils, and there is a possibility of coil ruptures. The object of the present invention is to avoid the rupture of helical coils wound around the outer surface of a vacuum container against heat expansion if any. That is, bellows or heat expansion absorbing means are disposed to a cross section of a helical type vacuum container. With such a constitution, thermal expansion of helical coils per se due to temperature elevation of the coils during electric supply can be absorbed by expansion of the bellows or absorption of the heat expansion absorbing means. Further, this can be attained by arranging shear pins in the direction perpendicular to the bellows axis so that the bellows are not distorted when the helical coils are wound around the helical type vacuum container. (I.S.)

  20. Vacuum considerations: summary

    International Nuclear Information System (INIS)

    Blechschmidt, D.; Halama, H.J.

    1978-01-01

    A summary is given of the efforts of a vacuum systems study group of the workshop on a Heavy Ion Demonstration Experiment (HIDE) for heavy ion fusion. An inadequate knowledge of cross-sections prevents a more concrete vacuum system design. Experiments leading to trustworthy numbers for charge exchange, stripping and capture cross-sections are badly needed and should start as soon as possible. In linacs, beam loss will be almost directly proportional to the pressure inside the tanks. The tanks should, therefore, be built in such a way that they can be baked-out in situ to improve their vacuum, especially if the cross-sections turn out to be higher than anticipated. Using standard UHV techniques and existing pumps, an even lower pressure can be achieved. The vacuum system design for circular machines will be very difficult, and in some cases, beyond the present state-of-the-art

  1. Handbook of vacuum technology

    CERN Document Server

    2016-01-01

    This comprehensive, standard work has been updated to remain an important resource for all those needing detailed knowledge of the theory and applications of vacuum technology. With many numerical examples and illustrations to visualize the theoretical issues.

  2. Cold Vacuum Drying Facility

    Data.gov (United States)

    Federal Laboratory Consortium — Located near the K-Basins (see K-Basins link) in Hanford's 100 Area is a facility called the Cold Vacuum Drying Facility (CVDF).Between 2000 and 2004, workers at the...

  3. TFTR diagnostic vacuum controller

    International Nuclear Information System (INIS)

    Olsen, D.; Persons, R.

    1981-01-01

    The TFTR diagnostic vacuum controller (DVC) provides in conjunction with the Central Instrumentation Control and Data Acquisition System (CICADA), control and monitoring for the pumps, valves and gauges associated with each individual diagnostic vacuum system. There will be approximately 50 systems on TFTR. Two standard versions of the controller (A and B) wil be provided in order to meet the requirements of two diagnostic manifold arrangements. All pump and valve sequencing, as well as protection features, will be implemented by the controller

  4. A Planck Vacuum Cosmology

    Directory of Open Access Journals (Sweden)

    Daywitt W. C.

    2009-04-01

    Full Text Available Both the big-bang and the quasi-steady-state cosmologies originate in some type of Planck state. This paper presents a new cosmological theory based on the Planck- vacuum negative-energy state, a state consisting of a degenerate collection of negative- energy Planck particles. A heuristic look at the Einstein field equation provides a con- vincing argument that such a vacuum state could provide a theoretical explanation for the visible universe.

  5. Automation of Aditya vacuum control system based on CODAC Core System

    Energy Technology Data Exchange (ETDEWEB)

    Raulji, Vismaysinh D., E-mail: vismay@ipr.res.in; Pujara, Harshad; Arambhadiya, Bharat; Jadeja, Kumarpalsinh; Bhatt, Shailesh; Rajpal, Rachana

    2016-11-15

    Highlights: • Monitor and control of vacuum control system based on CODAC Core System. • Communication between SIEMENS PLC and open source software EPICS. • With CODAC Core easy to configure and programming of slow controller. - Abstract: The main objective of vacuum control system is to provide ultrahigh vacuum for Aditya Tokamak operations. Aditya Vacuum vessel is having four vacuum pumping lines. To demonstrate implementation of automation; a study case is under taken by automating single Pumping Line of the Aditya vacuum system using CODAC Core System (CCS). Currently, vacuum system is operated manually. The CCS based control system allows remote control, monitoring, alarm handling of vacuum parameters. The CODAC Core System is the Linux based software package that is distributed by ITER Organization for the development of Plant System I&C software. CODAC Core System includes EPICS, CSS (Control System Studio) etc. CSS is used for HMI (Human Machine Interface), alarms and archives. SDD (Self Description Data) tool is used to configure plant system I&C. SDD Editor is an Eclipse based application to define the plant system, interface, I&C component, interfaced signals, configure variable. SCADA (Supervisory Control and Data Acquisition) system is developed in CSS. Data is transferred between PLC and CSS through EPICS. The complete system is tested with Aditya Vacuum Control System with process interlocks. Operator interface is also developed using Lab VIEW as a choice of the user. This paper will describe the salient features of the developed control system in detail.

  6. Laparoscopy After Previous Laparotomy

    Directory of Open Access Journals (Sweden)

    Zulfo Godinjak

    2006-11-01

    Full Text Available Following the abdominal surgery, extensive adhesions often occur and they can cause difficulties during laparoscopic operations. However, previous laparotomy is not considered to be a contraindication for laparoscopy. The aim of this study is to present that an insertion of Veres needle in the region of umbilicus is a safe method for creating a pneumoperitoneum for laparoscopic operations after previous laparotomy. In the last three years, we have performed 144 laparoscopic operations in patients that previously underwent one or two laparotomies. Pathology of digestive system, genital organs, Cesarean Section or abdominal war injuries were the most common causes of previouslaparotomy. During those operations or during entering into abdominal cavity we have not experienced any complications, while in 7 patients we performed conversion to laparotomy following the diagnostic laparoscopy. In all patients an insertion of Veres needle and trocar insertion in the umbilical region was performed, namely a technique of closed laparoscopy. Not even in one patient adhesions in the region of umbilicus were found, and no abdominal organs were injured.

  7. The evaluation of different environments in ultra-high frequency induction sintered powder metal compacts

    International Nuclear Information System (INIS)

    Cavdar, P. S.; Cavdar, U.

    2015-01-01

    The application of the iron based Powder Metal (PM) compacts in Ultra-High Frequency Induction Sintering (UHFIS) was reviewed for different environments. The three different environments: atmosphere, argon and vacuum were applied to the PM compacts. Iron based PM compacts were sintered at 1120 degree centigrade for a total of 550 seconds by using induction sintering machines with 2.8 kW power and 900 kHz frequency. Micro structural properties, densities, roughness and micro hardness values were obtained for all environments. The results were compared with each other. (Author)

  8. Thin walls in regions with vacuum energy

    Energy Technology Data Exchange (ETDEWEB)

    Garfinkle, D [Florida Univ., Gainesville, FL (USA). Dept. of Physics; Vuille, C [Embry-Riddle Aeronautical Univ., Prescott, AZ (USA). Dept. of Math/Physical Science

    1989-12-01

    The motion of a thin wall is treated in the case where the regions on either side of the wall have vacuum energy. This treatment generalises previous results involving domain walls in vacuum and also previous results involving the properties of false vacuum bubbles. The equation of state for a domain wall is{tau} = {sigma} where {tau} is the tension in the wall and {sigma} is the energy density. We consider the motion of a more general class of walls having equation of state {tau}{Gamma}{sigma} with 0{le}{Gamma}{le}1. Spherically symmetric and planar symmetric walls are examined. We also find the global structure of the wall spacetime. (author).

  9. Vacuum instability in scalar field theories

    International Nuclear Information System (INIS)

    McKane, A.J.

    1978-09-01

    Scalar field theories with an interaction of the form gphisup(N) have no stable vacuum state for some range of values of their coupling constant, g. This thesis reports calculations of vacuum instability in such theories. Using the idea that the tunnelling out of the vacuum state is described by the instanton solutions of the theory, the imaginary part of the vertex functions is calculated for the massless theory in the one-loop approximation, near the dimension dsub(c) = 2N/N-2, where the theory is just renormalisable. The calculation differs from previous treatments in that dimensional regularisation is used to control the ultra-violet divergences of the theory. In this way previous analytic calculations in conformally invariant field theories are extended to the case where the theory is almost conformally invariant, since it is now defined in dsub(c) - epsilon dimensions (epsilon > 0). (author)

  10. Vector Susceptibility of QCD Vacuum from an Effective Quark-Quark Interaction

    Institute of Scientific and Technical Information of China (English)

    ZONG Hong-Shi; QI Shi; CHEN Wei; WU Xiao-Hua

    2003-01-01

    .A new approach for calculating vacuum susceptibilities from an effective quark-quark interaction model is derived. As a special case, the vector vacuum susceptibility is calculated. A comparison with the results of the previous approaches is given.

  11. Ultra high vacuum fracture and transfer device for AES analysis of irradiated austenitic stainless steel

    International Nuclear Information System (INIS)

    Urie, M.W.; Panayotou, N.F.; Robinson, J.E.

    1980-01-01

    An ultrahigh vacuum fracture and transfer device for analysis of irradiated and non-irradiated SS 316 fuel cladding is described. Mechanical property tests used to study the behavior of cladding during reactor transient over-power conditions are reported. The stress vs temperature curves show minimal differences between unirradiated cladding and unfueled cladding. The fueled cladding fails at a lower temperature. All fueled specimens failed in an intergranular mode

  12. In-vacuum scattered light reduction with black cupric oxide surfaces for sensitive fluorescence detection.

    Science.gov (United States)

    Norrgard, E B; Sitaraman, N; Barry, J F; McCarron, D J; Steinecker, M H; DeMille, D

    2016-05-01

    We demonstrate a simple and easy method for producing low-reflectivity surfaces that are ultra-high vacuum compatible, may be baked to high temperatures, and are easily applied even on complex surface geometries. Black cupric oxide (CuO) surfaces are chemically grown in minutes on any copper surface, allowing for low-cost, rapid prototyping, and production. The reflective properties are measured to be comparable to commercially available products for creating optically black surfaces. We describe a vacuum apparatus which uses multiple blackened copper surfaces for sensitive, low-background detection of molecules using laser-induced fluorescence.

  13. Vacuum arc anode phenomena

    International Nuclear Information System (INIS)

    Miller, H.C.

    1976-01-01

    A brief review of anode phenomena in vacuum arcs is presented. Discussed in succession are: the transition of the arc into the anode spot mode; the temperature of the anode before, during and after the anode spot forms; and anode ions. Characteristically the anode spot has a temperature of the order of the atmospheric boiling point of the anode material and is a copious source of vapor and energetic ions. The dominant mechanism controlling the transition of the vacuum arc into the anode spot mode appears to depend upon the electrode geometry, the electrode material, and the current waveform of the particular vacuum arc being considered. Either magnetic constriction in the gap plasma or gross anode melting can trigger the transition; indeed, a combination of the two is a common cause of anode spot formation

  14. Vacuum Arc Ion Sources

    CERN Document Server

    Brown, I.

    2013-12-16

    The vacuum arc ion source has evolved into a more or less standard laboratory tool for the production of high-current beams of metal ions, and is now used in a number of different embodiments at many laboratories around the world. Applications include primarily ion implantation for material surface modification research, and good performance has been obtained for the injection of high-current beams of heavy-metal ions, in particular uranium, into particle accelerators. As the use of the source has grown, so also have the operational characteristics been improved in a variety of different ways. Here we review the principles, design, and performance of vacuum arc ion sources.

  15. Vacuum fusion of uranium

    International Nuclear Information System (INIS)

    Stohr, J.A.

    1957-01-01

    After having outlined that vacuum fusion and moulding of uranium and of its alloys have some technical and economic benefits (vacuum operations avoid uranium oxidation and result in some purification; precision moulding avoids machining, chip production and chemical reprocessing of these chips; direct production of the desired shape is possible by precision moulding), this report presents the uranium fusion unit (its low pressure enclosure and pumping device, the crucible-mould assembly, and the MF supply device). The author describes the different steps of cast production, and briefly comments the obtained results

  16. Baryogenesis in false vacuum

    Energy Technology Data Exchange (ETDEWEB)

    Hamada, Yuta [KEK Theory Center, IPNS, KEK, Tsukuba, Ibaraki (Japan); Yamada, Masatoshi [Kanazawa University, Institute for Theoretical Physics, Kanazawa (Japan)

    2017-09-15

    The null result in the LHC may indicate that the standard model is not drastically modified up to very high scales, such as the GUT/string scale. Having this in the mind, we suggest a novel leptogenesis scenario realized in the false vacuum of the Higgs field. If the Higgs field develops a large vacuum expectation value in the early universe, a lepton number violating process is enhanced, which we use for baryogenesis. To demonstrate the scenario, several models are discussed. For example, we show that the observed baryon asymmetry is successfully generated in the standard model with higher-dimensional operators. (orig.)

  17. Vacuum considerations summary

    International Nuclear Information System (INIS)

    1977-01-01

    The vacuum system for Heavy Ion Fusion machines can be divided according to pressure into 4 parts: (a) Ion Sources; (b) Linear Accelerators; (c) Circular Accelerators, Accumulators and Storage Rings; and (d) Reactors. Since ion sources will need rather conventional pumping arrangements and reactors will operate with greater pressures, depending on their mode of operation, only items b and c will be treated in this report. In particular, the vacuum system design will be suggested for the machines proposed by various scenarios arrived at during the workshop. High mass numbers will be assumed

  18. Handbook of vacuum physics

    CERN Document Server

    1964-01-01

    Handbook of Vacuum Physics, Volume 3: Technology is a handbook of vacuum physics, with emphasis on the properties of miscellaneous materials such as mica, oils, greases, waxes, and rubber. Accurate modern tables of physical constants, properties of materials, laboratory techniques, and properties of commercial pumps, gauges, and leak detectors are presented. This volume is comprised of 12 chapters and begins with a discussion on pump oils, divided into rotary pump oils and vapor pump oils. The next chapter deals with the properties and applications of greases, including outgassing and vapor pr

  19. Ultra-high temperature direct propulsion

    International Nuclear Information System (INIS)

    Araj, K.J.; Slovik, G.; Powell, J.R.; Ludewig, H.

    1987-01-01

    Potential advantages of ultra-high exhaust temperature (3000 K - 4000 K) direct propulsion nuclear rockets are explored. Modifications to the Particle Bed Reactor (PBR) to achieve these temperatures are described. Benefits of ultra-high temperature propulsion are discussed for two missions - orbit transfer (ΔV = 5546 m/s) and interplanetary exploration (ΔV = 20000 m/s). For such missions ultra-high temperatures appear to be worth the additional complexity. Thrust levels are reduced substantially for a given power level, due to the higher enthalpy caused by partial disassociation of the hydrogen propellant. Though technically challenging, it appears potentially feasible to achieve such ultra high temperatures using the PBR

  20. The fate of the Higgs vacuum

    Energy Technology Data Exchange (ETDEWEB)

    Burda, Philipp [Racah Institute of Physics, Hebrew University,Jerusalem 91904 (Israel); Centre for Particle Theory, Durham University,South Road, Durham, DH1 3LE (United Kingdom); Gregory, Ruth [Centre for Particle Theory, Durham University,South Road, Durham, DH1 3LE (United Kingdom); Perimeter Institute,31 Caroline Street North, Waterloo, ON, N2L 2Y5 (Canada); Moss, Ian G. [School of Mathematics and Statistics, Newcastle University,Newcastle Upon Tyne, NE1 7RU (United Kingdom)

    2016-06-06

    We have recently suggested that tiny black holes can act as nucleation seeds for the decay of the metastable Higgs vacuum. Previous results applied only to the nucleation of thin-wall bubbles, and covered a very small region of parameter space. This paper considers bubbles of arbitrary profile and reaches the same conclusion: black holes seed rapid vacuum decay. Seeded and unseeded nucleation rates are compared, and the gravitational back reaction of the bubbles is taken into account. The evolution of the bubble interior is described for the unseeded nucleation. Results are presented for the renormalisation group improved Standard Model Higgs potential, and a simple effective model representing new physics.

  1. The fate of the Higgs vacuum

    International Nuclear Information System (INIS)

    Burda, Philipp; Gregory, Ruth; Moss, Ian G.

    2016-01-01

    We have recently suggested that tiny black holes can act as nucleation seeds for the decay of the metastable Higgs vacuum. Previous results applied only to the nucleation of thin-wall bubbles, and covered a very small region of parameter space. This paper considers bubbles of arbitrary profile and reaches the same conclusion: black holes seed rapid vacuum decay. Seeded and unseeded nucleation rates are compared, and the gravitational back reaction of the bubbles is taken into account. The evolution of the bubble interior is described for the unseeded nucleation. Results are presented for the renormalisation group improved Standard Model Higgs potential, and a simple effective model representing new physics.

  2. A Foundation for Vacuuming Temporal Databases

    DEFF Research Database (Denmark)

    Skyt, Janne; Jensen, Christian Søndergaard; Mark, L.

    2003-01-01

    A wide range of real-world database applications, including financial and medical applications, are faced with accountability and traceability requirements. These requirements lead to the replacement of the usual update-in-place policy by an append-only policy that retain all previous states...... only received little attention. Such vacuuming is called for by, e.g., the laws of many countries and the policies of many businesses. Although necessary, with vacuuming, the database’s perfect recollection of the past may be compromised via, e.g., selective removal of records pertaining to past states...

  3. Ultrahigh-pressure transitions in solid hydrogen

    International Nuclear Information System (INIS)

    Mao, H.; Hemley, R.J.

    1994-01-01

    During the past five years, major progress has been made in the experimental study of solid hydrogen at ultrahigh pressures as a result of developments in diamond-cell technology. Pressures at which metallization has been predicted to occur have been reached (250--300 Gigapascals). Detailed studies of the dynamic, structural, and electronic properties of dense hydrogen reveal a system unexpectedly rich in physical phenomena, exhibiting a variety of transitions at ultrahigh pressures. This colloquium explores the study of dense hydrogen as an archetypal problem in condensed-matter physics

  4. Propagation of ultrahigh-energy cosmic rays

    Energy Technology Data Exchange (ETDEWEB)

    Stanev, Todor [Bartol Research Institute and Department of Physics and Astronomy, University of Delaware, Newark, DE 19716 (United States)], E-mail: stanev@bartol.udel.edu

    2009-06-15

    We briefly describe the energy loss processes of ultrahigh-energy protons, heavier nuclei and {gamma}-rays in interactions with the universal photon fields of the Universe. We then discuss the modification of the accelerated cosmic-ray energy spectrum in propagation by the energy loss processes and the charged cosmic-ray scattering in the extragalactic magnetic fields. The energy lost by the ultrahigh-energy cosmic rays goes into {gamma}-rays and neutrinos that carry additional information about the sources of highest energy particles. The new experimental results of the HiRes and the Auger collaborations are discussed in view of the predictions from propagation calculations.

  5. LEP vacuum chamber, prototype

    CERN Multimedia

    CERN PhotoLab

    1983-01-01

    Final prototype for the LEP vacuum chamber, see 8305170 for more details. Here we see the strips of the NEG pump, providing "distributed pumping". The strips are made from a Zr-Ti-Fe alloy. By passing an electrical current, they were heated to 700 deg C.

  6. Cryogenic vacuum pump design

    International Nuclear Information System (INIS)

    Bartlett, A.J.; Lessard, P.A.

    1984-01-01

    This paper is a review of the problems and tradeoffs involved in cryogenic vacuum pump analysis, design and manufacture. Particular attention is paid to the several issues unique to cryopumps, e.g., radiation loading, adsorption of noncondensible gases, and regeneration. A general algorithm for cryopump design is also proposed. 12 references

  7. ISR vacuum system

    CERN Multimedia

    CERN PhotoLab

    1971-01-01

    Some of the most important components of the vacuum system are shown. At the left, the rectangular box is a sputter-ion pump inside its bake-out oven. The assembly in the centre includes a sector valve, three roughing valves, a turbomolecular pump, a rotary backing pump and auxiliary equipment. At the right, the small elbow houses a Bayard-

  8. ISR vacuum system

    CERN Multimedia

    CERN PhotoLab

    1970-01-01

    A pressure of 5 x 10-11 Torr has been obtained repreatedly in this pilot section of the ISR vacuum system. The pilot section is 45 m long is pumped by 9 sputter-ion pumps pf 350 l/s pumping speed, and is baked out at 200 degrees C before each pump down.

  9. LEP Vacuum Chamber

    CERN Multimedia

    1983-01-01

    This is a cut-out of a LEP vacuum chamber for dipole magnets showing the beam channel and the pumping channel with the getter (NEG) strip and its insulating supports. A water pipe connected to the cooling channel can also be seen at the back.The lead radiation shield lining is also shown. See also 8305563X.

  10. Vacuum distilling vessel

    Energy Technology Data Exchange (ETDEWEB)

    Reik, H

    1928-12-27

    Vacuum distilling vessel for mineral oil and the like, characterized by the ring-form or polyconal stiffeners arranged inside, suitably eccentric to the casing, being held at a distance from the casing by connecting members of such a height that in the resulting space if necessary can be arranged vapor-distributing pipes and a complete removal of the residue is possible.

  11. Scroll vacuum pump

    Energy Technology Data Exchange (ETDEWEB)

    Morishita, Etsuo; Suganami, Takuya; Nishida, Mitsuhiro; Kitora, Yoshihisa; Yamamoto, Sakuei; Fujii, Kosaburo

    1988-02-25

    An effort is made to apply a scroll machine to development of a vacuum pump. In view of mechanical simplification and load patterns, the vacuum pump uses a rotating mechanism to produce paired vortices rotating around each center. Chip seal and atmospheric pressure are utilized for axial gap sealing while a spring and atmospheric pressure for the radial gap sealing. In both gaps, the sealing direction is stationary relative to the environment during rotation, making it much easier to achieve effective sealing as compared to oscillating pumps. Since the compression ratio is high in vacuum pumps, a zero top clearance form is adopted for the central portion of vortices and an gas release valve is installed in the rotating axis. A compact Oldham coupling with a small inertia force is installed behind the vortices to maintain the required phase relations between the vortices. These improvements result in a vacuum of 1 Pa for dry operation and 10/sup -2/ Pa for oil flooded operation of a single-stage scroll machine at 1800 rpm. (5 figs, 1 tab, 4 refs)

  12. On Lovelock vacuum solution

    OpenAIRE

    Dadhich, Naresh

    2010-01-01

    We show that the asymptotic large $r$ limit of all Lovelock vacuum and electrovac solutions with $\\Lambda$ is always the Einstein solution in $d \\geq 2n+1$ dimensions. It is completely free of the order $n$ of the Lovelock polynomial indicating universal asymptotic behaviour.

  13. The JET vacuum interspace system

    International Nuclear Information System (INIS)

    Orchard, J.; Scales, S.

    1999-01-01

    In the past JET has suffered from a number of vacuum leaks on components such as bellows, windows and feedthroughs due, in part, to the adverse conditions, including high mechanical forces, which may prevail during plasma operation. Therefore before the recent Tritium experiments on JET it was deemed prudent to manufacture and install items with a secondary containment or interspace in order to minimise the effect of failure of the primary vacuum barrier on both the leak integrity of the machine and the outcome of the experiments. This paper describes the philosophy, logistics, method and implementation of an integrated connection and monitoring system on the 330 interspaces currently in position on the JET machine. Using the JET leak database comparisons are drawn of leak failure rates of the components allied to the number of operational hours, prior to the system being present and after installation and commissioning, and the case of detection compared to the previous situation. An argument is also presented on the feasibility and adaptability of this system to any large complex machine and the benefits to be obtained in reduction of leaks and operational down time. (author)

  14. High current vacuum closing switch

    International Nuclear Information System (INIS)

    Dolgachev, G.I.; Maslennikov, D.D.; Romanov, A.S.; Ushakov, A.G.

    2005-01-01

    The paper proposes a powerful pulsed closing vacuum switch for high current commutation consisting of series of the vacuum diodes with near 1 mm gaps having closing time determined by the gaps shortening with the near-electrode plasmas [ru

  15. Expectations for ultra-high energy interactions

    International Nuclear Information System (INIS)

    Feynman, R.P.

    1978-01-01

    Strong interactions at ultra-high energies are discussed with emphasis on the hadrons produced in high energy collisions. Evidence is considered that quantum chromodynamics might be the right theory, and also some estimates are given of quantum chromodynamics asymptotic-freedom phenomena, the work under discussion being very preliminary. 6 references

  16. The symmetries of the vacuum

    International Nuclear Information System (INIS)

    Fleming, H.

    1985-01-01

    The vacuum equation of state required by cosmological inflation is taken seriously as a general property of the cosmological vacuum. This correctly restricts the class of theories which admit inflation. A model of such a vacuum is presented that leads naturally to the cosmological principle. (Author) [pt

  17. The π and Tensor Vacuum Susceptibilities from the Global Color Symmetry Model

    Institute of Scientific and Technical Information of China (English)

    ZONG Hong-Shi; PING Jia-Lun; YANG Hong-Ting; LU Xiao-Fu; WANG Fan

    2002-01-01

    A modified method for calculating the nonperturbative quark vacuum condensates from the global color symmetry model is derived. Within this approach it is shown that the treatment of quark vacuum condensates is different from that in the previous studies. As a special case we calculate the π and tensor vacuum susceptibilities. A comparison with the results of the other nonperturbative QCD approaches is given.

  18. Nonperturbative QED vacuum birefringence

    Energy Technology Data Exchange (ETDEWEB)

    Denisov, V.I.; Dolgaya, E.E.; Sokolov, V.A. [Physics Department, Moscow State University,Moscow, 119991 (Russian Federation)

    2017-05-19

    In this paper we represent nonperturbative calculation for one-loop Quantum Electrodynamics (QED) vacuum birefringence in presence of strong magnetic field. The dispersion relations for electromagnetic wave propagating in strong magnetic field point to retention of vacuum birefringence even in case when the field strength greatly exceeds Sauter-Schwinger limit. This gives a possibility to extend some predictions of perturbative QED such as electromagnetic waves delay in pulsars neighbourhood or wave polarization state changing (tested in PVLAS) to arbitrary magnetic field values. Such expansion is especially important in astrophysics because magnetic fields of some pulsars and magnetars greatly exceed quantum magnetic field limit, so the estimates of perturbative QED effects in this case require clarification.

  19. Compact vacuum insulation embodiments

    Science.gov (United States)

    Benson, D.K.; Potter, T.F.

    1992-04-28

    An ultra-thin compact vacuum insulation panel is comprised of two hard, but bendable metal wall sheets closely spaced apart from each other and welded around the edges to enclose a vacuum chamber. Glass or ceramic spacers hold the wall sheets apart. The spacers can be discrete spherical beads or monolithic sheets of glass or ceramic webs with nodules protruding therefrom to form essentially point' or line' contacts with the metal wall sheets. In the case of monolithic spacers that form line' contacts, two such spacers with the line contacts running perpendicular to each other form effectively point' contacts at the intersections. Corrugations accommodate bending and expansion, tubular insulated pipes and conduits, and preferred applications are also included. 26 figs.

  20. Compact vacuum insulation

    Science.gov (United States)

    Benson, D.K.; Potter, T.F.

    1993-01-05

    An ultra-thin compact vacuum insulation panel is comprised of two hard, but bendable metal wall sheets closely spaced apart from each other and welded around the edges to enclose a vacuum chamber. Glass or ceramic spacers hold the wall sheets apart. The spacers can be discrete spherical beads or monolithic sheets of glass or ceramic webs with nodules protruding therefrom to form essentially point'' or line'' contacts with the metal wall sheets. In the case of monolithic spacers that form line'' contacts, two such spacers with the line contacts running perpendicular to each other form effectively point'' contacts at the intersections. Corrugations accommodate bending and expansion, tubular insulated pipes and conduits, and preferred applications are also included.

  1. Dry vacuum pumps

    International Nuclear Information System (INIS)

    Sibuet, R

    2008-01-01

    For decades and for ultimate pressure below 1 mbar, oil-sealed Rotary Vane Pumps have been the most popular solution for a wide range of vacuum applications. In the late 80ies, Semiconductor Industry has initiated the development of the first dry roughing pumps. Today SC applications are only using dry pumps and dry pumping packages. Since that time, pumps manufacturers have developed dry vacuum pumps technologies in order to make them attractive for other applications. The trend to replace lubricated pumps by dry pumps is now spreading over many other market segments. For the Semiconductor Industry, it has been quite easy to understand the benefits of dry pumps, in terms of Cost of Ownership, process contamination and up-time. In this paper, Technology of Dry pumps, its application in R and D/industries, merits over conventional pumps and future growth scope will be discussed

  2. Temperature control in vacuum

    International Nuclear Information System (INIS)

    Dearnaley, G.

    1986-01-01

    The patent concerns a method for controlling the temperature of silicon wafers (or samples), during ion beam treatment of the wafers, in a vacuum. The apparatus and method are described for irradiation and temperature control of the samples. The wafers are mounted on a drum which is rotated through the ion beam, and are additionally heated by infra-red lamps to achieve the desired temperature. (U.K.)

  3. Electroweak vacuum geometry

    International Nuclear Information System (INIS)

    Lepora, N.; Kibble, T.

    1999-01-01

    We analyse symmetry breaking in the Weinberg-Salam model paying particular attention to the underlying geometry of the theory. In this context we find two natural metrics upon the vacuum manifold: an isotropic metric associated with the scalar sector, and a squashed metric associated with the gauge sector. Physically, the interplay between these metrics gives rise to many of the non-perturbative features of Weinberg-Salam theory. (author)

  4. Vacuum inhomogeneous cosmological models

    International Nuclear Information System (INIS)

    Hanquin, J.-L.

    1984-01-01

    The author presents some results concerning the vacuum cosmological models which admit a 2-dimensional Abelian group of isometries: classifications of these space-times based on the topological nature of their space-like hypersurfaces and on their time evolution, analysis of the asymptotical behaviours at spatial infinity for hyperbolical models as well as in the neighbourhood of the singularity for the models possessing a time singularity during their evolution. (Auth.)

  5. ELETTRA vacuum system

    International Nuclear Information System (INIS)

    Bernardini, M.; Daclon, F.; Giacuzzo, F.; Miertusova, J.; Pradal, F.; Kersevan, R.

    1993-01-01

    Elettra is a third-generation synchrotron light source which is being built especially for the use of high brilliance radiation from insertion devices and bending magnets. The UHV conditions in a storage ring lead to a longer beam lifetime - one of the most important criterion. The Elettra vacuum system presents some pecularities which cannot be found in any already existing machine. The final version of bending magnet vacuum chamber is presented. After chemical and thermal conditioning the specific outgassing rate of about 1.5e-12 Torr. liters sec -1 cm -2 was obtained. A microprocessor-controlled system has been developed to perform bake-out at the uniform temperature. The etched-foil type heaters are glued to the chamber and Microtherm insulation is used. UHV pumps based on standard triode sputter-ion pumps were modified with ST 707 NEG (Non Evaporable Getter) modules. A special installation enables the resistive activation of getters and significantly increases pumping speed for hydrogen and other residual gases (except methane and argon). All these technological innovations improve vacuum conditions in Elettra storage ring and consequently also the other parameters of the light source

  6. PARAFFIN SEPARATION VACUUM DISTILLATION

    Directory of Open Access Journals (Sweden)

    Zaid A. Abdulrahman

    2013-05-01

    Full Text Available Simulated column performance curves were constructed for existing paraffin separation vacuum distillation column in LAB plant (Arab Detergent Company/Baiji-Iraq. The variables considered in this study are the thermodynamic model option, top vacuum pressure, top and bottom temperatures, feed temperature, feed composition & reflux ratio. Also simulated columns profiles for the temperature, vapor & liquid flow rates composition were constructed. Four different thermodynamic model options (SRK, TSRK, PR, and ESSO were used, affecting the results within 1-25% variation for the most cases.The simulated results show that about 2% to 8 % of paraffin (C10, C11, C12, & C13 present at the bottom stream which may cause a problem in the LAB plant. The major variations were noticed for the top temperature & the  paraffin weight fractions at bottom section with top vacuum pressure. The bottom temperature above 240 oC is not recommended because the total bottom flow rate decreases sharply, where as  the weight fraction of paraffins decrease slightly. The study gives evidence about a successful simulation with CHEMCAD

  7. Vacuum system for LHC

    International Nuclear Information System (INIS)

    Groebner, O.

    1995-01-01

    The Large Hadron Collider (LHC) which is planned at CERN will be housed in the tunnel of the Large Electron Positron collider (LEP) and will store two counter-rotating proton beams with energies of up to 7 TeV in a 27 km accelerator/storage ring with superconducting magnets. The vacuum system for the LHC will be at cryogenic temperatures (between 1.9 and 20 K) and will be exposed to synchrotron radiation emitted by the protons. A stringent limitation on the vacuum is given by the energy deposition in the superconducting coils of the magnets due to nuclear scattering of the protons on residual gas molecules because this may provoke a quench. This effect imposes an upper limit to a local region of increased gas density (e.g. a leak), while considerations of beam lifetime (100 h) will determine more stringent requirements on the average gas density. The proton beam creates ions from the residual gas which may strike the vacuum chamber with sufficient energy to lead to a pressure 'run-away' when the net ion induced desorption yield exceeds a stable limit. These dynamic pressure effects will be limited to an acceptable level by installing a perforated 'beam screen' which shields the cryopumped gas molecules at 1.9 K from synchrotron radiation and which also absorbs the synchrotron radiation power at a higher and, therefore, thermodynamically more efficient temperature. (author)

  8. Anomalous vacuum expectation values

    International Nuclear Information System (INIS)

    Suzuki, H.

    1986-01-01

    The anomalous vacuum expectation value is defined as the expectation value of a quantity that vanishes by means of the field equations. Although this value is expected to vanish in quantum systems, regularization in general produces a finite value of this quantity. Calculation of this anomalous vacuum expectation value can be carried out in the general framework of field theory. The result is derived by subtraction of divergences and by zeta-function regularization. Various anomalies are included in these anomalous vacuum expectation values. This method is useful for deriving not only the conformal, chiral, and gravitational anomalies but also the supercurrent anomaly. The supercurrent anomaly is obtained in the case of N = 1 supersymmetric Yang-Mills theory in four, six, and ten dimensions. The original form of the energy-momentum tensor and the supercurrent have anomalies in their conservation laws. But the modification of these quantities to be equivalent to the original one on-shell causes no anomaly in their conservation laws and gives rise to anomalous traces

  9. Vacuum pumping concepts for ETF

    International Nuclear Information System (INIS)

    Homeyer, W.G.

    1980-09-01

    The Engineering Test Facility (ETF) poses unique vacuum pumping requirements due to its large size and long burn characteristics. These requirements include torus vacuum pumping initially and between burns and pumping of neutralized gas from divertor collector chambers. It was found that the requirements could be met by compound cryopumps in which molecular sieve 5A is used as the cryosorbent. The pumps, ducts, and vacuum valves required are large but fit with other ETF components and do not require major advances in vacuum pumping technology. Several additional design, analytical, and experimental studies were identified as needed to optimize designs and provide better design definition for the ETF vacuum pumping systems

  10. Ultra-high energy physics and standard basic principles

    Directory of Open Access Journals (Sweden)

    Gonzalez-Mestres Luis

    2014-04-01

    Full Text Available It has not yet been elucidated whether the observed flux suppression for ultra-high energy cosmic rays (UHECR at energies above ≃ 4 x 1019 eV is a signature of the Greisen-Zatsepin-Kuzmin (GZK cutoff or a consequence of other phenomena. In both cases, violations of the standard fundamental principles of Physics can be present and play a significant role. They can in particular modify cosmic-ray interactions, propagation or acceleration at very high energy. Thus, in a long-term program, UHECR data can hopefully be used to test relativity, quantum mechanics, energy and momentum conservation, vacuum properties... as well as the elementariness of standard particles. Data on cosmic rays at energies ≃ 1020 eV may also be sensitive to new physics generated well beyond Planck scale. A typical example is provided by the search for possible signatures of a Lorentz symmetry violation (LSV associated to a privileged local reference frame (the "vacuum rest frame", VRF. If a VRF exists, the internal structure of standard particles at ultra-high energy can undergo substantial modifications. Similarly, the conventional particle symmetries may cease to be valid at such energies instead of heading to a grand unification and the structure of vacuum may no longer be governed by standard quantum field theory. Then, the question whether the notion of Planck scale still makes sense clearly becomes relevant and the very grounds of Cosmology can undergo essential modifications. UHECR studies naturally interact with the interpretation of WMAP and Planck observations. Recent Planck data analyses tend to confirm the possible existence of a privileged space direction. If the observed phenomenon turns out to be a signature of the spinorial space-time (SST we suggested in 1996-97, then conventional Particle Physics may correspond to the local properties of standard matter at low enough energy and large enough distances. This would clearly strengthen the cosmological

  11. Extremely-high vacuum pressure measurement by laser ionization

    International Nuclear Information System (INIS)

    Kokubun, Kiyohide

    1991-01-01

    Laser ionization method has the very high sensitivity for detecting atoms and molecules. Hurst et al. successfully detected a single Cs atom by means of resonance ionization spectroscopy developed by them. Noting this high sensitivity, the authors have attempted to apply the laser ionization method to measure gas pressure, particularly in the range down to extremely high vacuum. At present, hot cathode ionization gauges are used for measuring gas pressure down to ultrahigh vacuum, however, those have a number of disadvantages. The pressure measurement using lasers does not have such disadvantages. The pressure measurement utilizing the laser ionization method is based on the principle that when laser beam is focused through a lens, the amount of atom or molecule ions generated in the focused space region is proportional to gas pressure. In this paper, the experimental results are presented on the nonresonant multiphoton ionization characteristics of various kinds of gases, the ion detection system with high sensitivity and an extremely high vacuum system prepared for the laser ionization experiment. (K.I.)

  12. Vacuum system of tandem type electrostatic accelerator of Kyushu University

    International Nuclear Information System (INIS)

    Nakajima, Yutaka

    1981-01-01

    In the tandem type electrostatic accelerator of Kyushu University, the problem of vacuum in the beam transport system including the accelerator tube has been considered as one of the important elements for the performance of the electrostatic accelerator from the beginning of construction. Though the three-stage tandem accelerating scheme was considered as the beam transport system at the beginning of the program, in which the existing 6 MV Van de Graaf accelerator was to be used as the injector, three types of ion sources are prepared at present; the sputter ion source to generate negative heavy ions, the polarizing ion source to generate negative polarized protons or deuterons, and direct extraction type negative ion source. Ultrahigh evacuating system, in which the sputter ion pump is mainly employed, and the turbo-molecular pump is used supplementarily, was installed in the vacuum system. The vacuum of approximately 10 - 9 Torr level off-beam at the inlet or outlet of the accelerator tube and approximately 10 - 8 Torr level in the tubing section in the center terminal were achieved. Since the upper limit of withstand voltage of the accelerating tube was not able to be satisfied for the insufficient baking at the beginning, it was finally decided that the accelerating tube should be heated by directly supplying power to the electrode through low voltage discharge in the tube. This method enabled the generated voltage at the terminal to exceed 10 MV. (Wakatsuki, Y.)

  13. Multiple (Two) Met Bel 601 In Series Ultimate Vacuum Testing

    Energy Technology Data Exchange (ETDEWEB)

    Restivo, M. [Savannah River Site (SRS), Aiken, SC (United States). Savannah River National Lab. (SRNL)

    2016-09-30

    SRNL Environmental and Chemical Process Technology (E&CPT) was requested to perform testing of vacuum pumps per a verbal request from the Customer, SRNL Hydrogen Processing Technology. Tritium Operations is currently having difficulties procuring the Normetex™® Model 15 m3/hr (9 CFM) vacuum pump (formerly Normetex Pompes, now EumecaSARL). One possible solution proposed by Hydrogen Processing Technology personnel is to use two Senior Aerospace Metal Bellows MB-601 vacuum pumps piped with the heads in series, and the pumps in series (Figure 1 below). This memorandum documents the ultimate vacuum testing that was performed to determine if this concept was a viable alternate vacuum pump strategy. This testing dovetails with previous pump evaluations documented in references 1 and 2.

  14. Design of ultrahigh brightness solar-pumped disk laser.

    Science.gov (United States)

    Liang, Dawei; Almeida, Joana

    2012-09-10

    To significantly improve the solar-pumped laser beam brightness, a multi-Fresnel lens scheme is proposed for side-pumping either a single-crystal Nd:YAG or a core-doped ceramic Sm(3+) Nd:YAG disk. Optimum laser system parameters are found through ZEMAX and LASCAD numerical analysis. An ultrahigh laser beam figure of merit B of 53 W is numerically calculated, corresponding to a significant enhancement of more than 180 times over the previous record. 17.7 W/m(2) collection efficiency is also numerically attained. The strong thermal effects that have hampered present-day rod-type solar-pumped lasers can also be largely alleviated.

  15. Ultrahigh-energy cosmic-ray spectrum

    International Nuclear Information System (INIS)

    Hill, C.T.; Schramm, D.N.

    1985-01-01

    We analyze the evolution of the ultrahigh-energy cosmic-ray spectrum upon traversing the 2.7 0 K microwave background with respect to pion photoproduction, pair-production reactions, and cosmological effects. Our approach employs exact transport equations which manifestly conserve nucleon number and embody the laboratory details of these reactions. A spectrum enhancement appears around 6 x 10 19 eV due to the ''pile-up'' of energy-degraded nucleons, and a ''dip'' occurs around 10 19 eV due to combined effects. Both of these features appear in the observational spectrum. We analyze the resulting neutrino spectrum and the effects of cosmological source distributions. We present a complete model of the ultrahigh-energy spectrum and anisotropy in reasonable agreement with observation and which predicts an observable electron-neutrino spectrum

  16. The vacuum platform

    Science.gov (United States)

    McNab, A.

    2017-10-01

    This paper describes GridPP’s Vacuum Platform for managing virtual machines (VMs), which has been used to run production workloads for WLCG and other HEP experiments. The platform provides a uniform interface between VMs and the sites they run at, whether the site is organised as an Infrastructure-as-a-Service cloud system such as OpenStack, or an Infrastructure-as-a-Client system such as Vac. The paper describes our experience in using this platform, in developing and operating VM lifecycle managers Vac and Vcycle, and in interacting with VMs provided by LHCb, ATLAS, ALICE, CMS, and the GridPP DIRAC service to run production workloads.

  17. Ultrahigh energy neutrinos and nonlinear QCD dynamics

    International Nuclear Information System (INIS)

    Machado, Magno V.T.

    2004-01-01

    The ultrahigh energy neutrino-nucleon cross sections are computed taking into account different phenomenological implementations of the nonlinear QCD dynamics. Based on the color dipole framework, the results for the saturation model supplemented by the Dokshitzer-Gribov-Lipatov-Altarelli-Parisi (DGLAP) evolution as well as for the Balitskii-Fadin-Kuraev-Lipatov (BFKL) formalism in the geometric scaling regime are presented. They are contrasted with recent calculations using next-to-leading order DGLAP and unified BFKL-DGLAP formalisms

  18. Scaling violations at ultra-high energies

    International Nuclear Information System (INIS)

    Tung, W.K.

    1979-01-01

    The paper discusses some of the features of high energy lepton-hadron scattering, including the observed (Bjorken) scaling behavior. The cross-sections where all hadron final states are summed over, are examined and the general formulas for the differential cross-section are examined. The subjects of scaling, breaking and phenomenological consequences are studied, and a list of what ultra-high energy neutrino physics can teach QCD is given

  19. R&D ERL: Vacuum

    Energy Technology Data Exchange (ETDEWEB)

    Mapes, M.; Smart, L.; Weiss, D.; Steszyn, A.; Todd, R.

    2010-01-01

    The ERL Vacuum systems are depicted in a figure. ERL has eight vacuum volumes with various sets of requirements. A summary of vacuum related requirements is provided in a table. Five of the eight volumes comprise the electron beamline. They are the 5-cell Superconducting RF Cavity, Superconducting e-gun, injection, loop and beam dump. Two vacuum regions are the individual cryostats insulating the 5-cell Superconducting RF Cavity and the Superconducting e-gun structures. The last ERL vacuum volume not shown in the schematic is the laser transport line. The beamline vacuum regions are separated by electropneumatic gate valves. The beam dump is common with loop beamline but is considered a separate volume due to geometry and requirements. Vacuum in the 5-cell SRF cavity is maintained in the {approx}10{sup -9} torr range at room temperature by two 20 l/s ion pumps and in the e-gun SRF cavity by one 60 l/s ion pump. Vacuum in the SRF cavities operated at 2{sup o}K is reduced to low 10{sup -11} torr via cryopumping of the cavity walls. The cathode of the e-gun must be protected from poisoning, which can occur if vacuum adjacent to the e-gun in the injection line exceeds 10-11 torr range in the injection warm beamline near the e-gun exit. The vacuum requirements for beam operation in the loop and beam dump are 10-9 torr range. The beamlines are evacuated from atmospheric pressure to high vacuum level with a particulate free, oil free turbomolecular pumping cart. 25 l/s shielded ion pumps distributed throughout the beamlines maintain the vacuum requirement. Due to the more demanding vacuum requirement of the injection beamline proximate to the e-gun, a vacuum bakeout of the injection beamline is required. In addition, two 200 l/s diode ion pumps and supplemental pumping provided by titanium sublimation pumps are installed in the injection line just beyond the exit of the e-gun. Due to expected gas load a similar pumping arrangement is planned for the beam dump. The

  20. R and D ERL: Vacuum

    International Nuclear Information System (INIS)

    Mapes, M.; Smart, L.; Weiss, D.; Steszyn, A.; Todd, R.

    2010-01-01

    The ERL Vacuum systems are depicted in a figure. ERL has eight vacuum volumes with various sets of requirements. A summary of vacuum related requirements is provided in a table. Five of the eight volumes comprise the electron beamline. They are the 5-cell Superconducting RF Cavity, Superconducting e-gun, injection, loop and beam dump. Two vacuum regions are the individual cryostats insulating the 5-cell Superconducting RF Cavity and the Superconducting e-gun structures. The last ERL vacuum volume not shown in the schematic is the laser transport line. The beamline vacuum regions are separated by electropneumatic gate valves. The beam dump is common with loop beamline but is considered a separate volume due to geometry and requirements. Vacuum in the 5-cell SRF cavity is maintained in the ∼10 -9 torr range at room temperature by two 20 l/s ion pumps and in the e-gun SRF cavity by one 60 l/s ion pump. Vacuum in the SRF cavities operated at 2 o K is reduced to low 10 -11 torr via cryopumping of the cavity walls. The cathode of the e-gun must be protected from poisoning, which can occur if vacuum adjacent to the e-gun in the injection line exceeds 10-11 torr range in the injection warm beamline near the e-gun exit. The vacuum requirements for beam operation in the loop and beam dump are 10-9 torr range. The beamlines are evacuated from atmospheric pressure to high vacuum level with a particulate free, oil free turbomolecular pumping cart. 25 l/s shielded ion pumps distributed throughout the beamlines maintain the vacuum requirement. Due to the more demanding vacuum requirement of the injection beamline proximate to the e-gun, a vacuum bakeout of the injection beamline is required. In addition, two 200 l/s diode ion pumps and supplemental pumping provided by titanium sublimation pumps are installed in the injection line just beyond the exit of the e-gun. Due to expected gas load a similar pumping arrangement is planned for the beam dump. The cryostat vacuum thermally

  1. Waveguide quantum electrodynamics in squeezed vacuum

    Science.gov (United States)

    You, Jieyu; Liao, Zeyang; Li, Sheng-Wen; Zubairy, M. Suhail

    2018-02-01

    We study the dynamics of a general multiemitter system coupled to the squeezed vacuum reservoir and derive a master equation for this system based on the Weisskopf-Wigner approximation. In this theory, we include the effect of positions of the squeezing sources which is usually neglected in the previous studies. We apply this theory to a quasi-one-dimensional waveguide case where the squeezing in one dimension is experimentally achievable. We show that while dipole-dipole interaction induced by ordinary vacuum depends on the emitter separation, the two-photon process due to the squeezed vacuum depends on the positions of the emitters with respect to the squeezing sources. The dephasing rate, decay rate, and the resonance fluorescence of the waveguide-QED in the squeezed vacuum are controllable by changing the positions of emitters. Furthermore, we demonstrate that the stationary maximum entangled NOON state for identical emitters can be reached with arbitrary initial state when the center-of-mass position of the emitters satisfies certain conditions.

  2. Study on reactor building structure using ultrahigh strength materials, 1

    International Nuclear Information System (INIS)

    Ishimura, Kikuo; Odajima, Masahiro; Irino, Kazuo; Hashiba, Toshio.

    1991-01-01

    This study was promoted to be aimed at realization of the optimal nuclear reactor building structure of the future. As the first step, the study regarding ultrahigh strength reinforced concrete (abbr. RC) shear wall was selected. As the result of various tests, the application of ultrahigh strength RC shear walls was verified. The tests conducted were relevant to; ultrahigh strength concrete material tests; pure shear tests of RC flat panels; and bending shear tests and its simulation analysis of RC shear walls. (author)

  3. Changing MFTF vacuum environment

    International Nuclear Information System (INIS)

    Margolies, D.; Valby, L.

    1982-12-01

    The Mirror Fusion Test Facility (MFTF) vacuum vessel will be about 60m long and 10m in diameter at the widest point. The allowable operating densities range from 2 x 10 9 to 5 x 10 10 particles per cc. The maximum leak rate of 10 - 6 tl/sec is dominated during operation by the deliberately injected cold gas of 250 tl/sec. This gas is pumped by over 1000 square meters of cryopanels, external sorption pumps and getters. The design and requirements have changed radically over the past several years, and they are still not in final form. The vacuum system design has also changed, but more slowly and less radically. This paper discusses the engineering effort necessary to meet these stringent and changing requirements. Much of the analysis of the internal systems has been carried out using a 3-D Monte Carlo computer code, which can estimate time dependent operational pressures. This code and its use will also be described

  4. Of vacuum and gas

    CERN Multimedia

    Katarina Anthony

    2015-01-01

    A new LHCb programme is delving into uncharted waters for the LHC: exploring how protons interact with noble gases inside the machine pipe. While, at first glance, it may sound risky for the overall quality of the vacuum in the machine, the procedure is safe and potentially very rich in rewards. The results could uncover the high-energy helium-proton cross-section (with all the implications thereof), explore new boundaries of the quark-gluon plasma and much more.   As the beam passes through LHCb, interactions with neon gas allow the experiment to measure the full beam profile. In this diagram, beam 1 (blue) and beam 2 (red) are measured by the surrounding VELO detector. It all begins with luminosity. In 2011, LHCb set out to further improve its notoriously precise measurements of the beam profile, using the so-called Beam-Gas Imaging (BGI) method. BGI does exactly what it says on the tin: a small amount of gas is inserted into the vacuum, increasing the rate of collisions around the interaction ...

  5. LHC vacuum system

    CERN Document Server

    Gröbner, Oswald

    1999-01-01

    The Large Hadron Collider (LHC) project, now in the advanced construction phase at CERN, comprises two proton storage rings with colliding beams of 7-TeV energy. The machine is housed in the existing LEP tunnel with a circumference of 26.7 km and requires a bending magnetic field of 8.4 T with 14-m long superconducting magnets. The beam vacuum chambers comprise the inner 'cold bore' walls of the magnets. These magnets operate at 1.9 K, and thus serve as very good cryo-pumps. In order to reduce the cryogenic power consumption, both the heat load from synchrotron radiation emitted by the proton beams and the resistive power dissipation by the beam image currents have to be absorbed on a 'beam screen', which operates between 5 and 20 K and is inserted inside the vacuum chamber. The design of this beam screen represents a technological challenge in view of the numerous and often conflicting requirements and the very tight mechanical tolerances imposed. The synchrotron radiation produces strong outgassing from the...

  6. Low temperature ultrahigh vacuum cross-sectional scanning tunneling microscope for luminescence measurements

    International Nuclear Information System (INIS)

    Khang, Yoonho; Park, Yeonjoon; Salmeron, Miquel; Weber, Eicke R.

    1999-01-01

    We have constructed a scanning tunneling microscope with simultaneous light collection capabilities in order to investigate the opto-electronic properties of semiconductors. The microscope has in situ sample cleavage mechanism for cross-sectional sample. In order to reach low temperature (4 K), we used a specially designed cryostat. The efficiency of light collection generated in the tip-surface junction was greatly improved by use of a small parabolic mirror with the tip located at its focal point. (c) 1999 American Institute of Physics

  7. A simple, ultrahigh vacuum compatible scanning tunneling microscope for use at variable temperatures

    NARCIS (Netherlands)

    Mugele, Friedrich Gunther; Kloos, Ch.; Leiderer, P.; Moller, R.

    1996-01-01

    We present the construction of a very compact scanning tunneling microscope (STM) which can be operated at temperatures between 4 and 350 K. The tip and a tiny tip holder are the only movable parts, whereas the sample and the piezoscanner are rigidly attached to the body of the STM. This leads to an

  8. Ultra-High Speed Visualization of the Flashing Instability in Micron Size Nozzles under Vacuum Conditions

    KAUST Repository

    Alghamdi, Tariq A.

    2017-01-01

    fluid, but also methanol, ethanol and 1-bromopropane were tested. Surprisingly, minimum intensity profiles revealed spray angles close to 𝜃𝑠 ~360°, meaning drops are ejected in all directions. Also, I measured speeds of bubble expansion up to 140 m

  9. High and ultra-high vacuum pumping techniques: applications in accelerators and storage rings

    International Nuclear Information System (INIS)

    Schaefer, G.

    1988-01-01

    A survey is given on gas transfer pumps, especially Turbomolecular pumps, and entrapment pumps (cryopumps and getter pumps) mainly with regard to their application in evacuating particle accelerators and storage rings. (A.C.A.S.) [pt

  10. Particle contamination in vacuum systems

    International Nuclear Information System (INIS)

    Martignac, J.; Bonin, B.; Henriot, C.; Poupeau, J.P.; Koltchakian, I.; Kocic, D.; Herbeaux, Ch.; Marx, J.P.

    1996-01-01

    Many vacuum devices, like RF cavities, are sensitive to particle contamination. This fact has motivated a considerable effort of cleanliness from the SRF community. The present paper reports the first results of a general study trying to identify the most contaminating steps during assembly and vacuum operation of the cavity. The steps investigated here are gasket assembly, evacuation and venting of the vacuum system, and operation of sputter ion pumps. (author)

  11. Vacuum guidelines for ISA insertions

    International Nuclear Information System (INIS)

    Edwards, D. Jr.

    1976-01-01

    Vacuum requirements place design restrictions on the ISA insertions. The vacuum tube diameter, given a distance L between pumps, is determined by the desorption of molecules from the wall under the impact of ions created by the beam, whereas the thickness of the tube must be sufficient to prevent collapse. In addition, the entire vacuum chamber must be able to be baked out at approximately 200 0 C

  12. Particle contamination in vacuum systems

    International Nuclear Information System (INIS)

    Martignac, J.; Bonin, B.; Henriot, C.; Poupeau, J.P.; Koltchakian, I.; Kocic, D.; Herbeaux, Ch.; Marx, J.P.

    1996-01-01

    Many vacuum devices, like RF cavities, are sensitive to particle contamination. This fact has motivated a considerable effort of cleanliness from the SRF community. The first results of a general study trying to identify the most contaminating steps during assembly and vacuum operation of the cavity is reported. The steps investigated here are gasket assembly, evacuation and venting of the vacuum system, and operation of sputter ion pumps. (author)

  13. Big Bang or vacuum fluctuation

    International Nuclear Information System (INIS)

    Zel'dovich, Ya.B.

    1980-01-01

    Some general properties of vacuum fluctuations in quantum field theory are described. The connection between the ''energy dominance'' of the energy density of vacuum fluctuations in curved space-time and the presence of singularity is discussed. It is pointed out that a de-Sitter space-time (with the energy density of the vacuum fluctuations in the Einstein equations) that matches the expanding Friedman solution may describe the history of the Universe before the Big Bang. (P.L.)

  14. Cavity Control and Cooling of Nanoparticles in High Vacuum

    Science.gov (United States)

    Millen, James

    2016-05-01

    Levitated systems are a fascinating addition to the world of optically-controlled mechanical resonators. It is predicted that nanoparticles can be cooled to their c.o.m. ground state via the interaction with an optical cavity. By freeing the oscillator from clamping forces dissipation and decoherence is greatly reduced, leading to the potential to produce long-lived, macroscopically spread, mechanical quantum states, allowing tests of collapse models and any mass limit of quantum physics. Reaching the low pressures required to cavity-cool to the ground state has proved challenging. Our approach is to cavity cool a beam of nanoparticles in high vacuum. We can cool the c.o.m. motion of nanospheres, and control the rotation of nanorods, with the potential to produce cold, aligned nanostructures. Looking forward, we will utilize novel microcavities to enhance optomechanical cooling, preparing particles in a coherent beam ideally suited to ultra-high mass interferometry at 107 a.m.u.

  15. Vacuum metastability with black holes

    Energy Technology Data Exchange (ETDEWEB)

    Burda, Philipp [Centre for Particle Theory, Durham University,South Road, Durham, DH1 3LE (United Kingdom); Gregory, Ruth [Centre for Particle Theory, Durham University,South Road, Durham, DH1 3LE (United Kingdom); Perimeter Institute, 31 Caroline Street North,Waterloo, ON, N2L 2Y5 (Canada); Moss, Ian G. annd [School of Mathematics and Statistics, Newcastle University,Newcastle Upon Tyne, NE1 7RU (United Kingdom)

    2015-08-24

    We consider the possibility that small black holes can act as nucleation seeds for the decay of a metastable vacuum, focussing particularly on the Higgs potential. Using a thin-wall bubble approximation for the nucleation process, which is possible when generic quantum gravity corrections are added to the Higgs potential, we show that primordial black holes can stimulate vacuum decay. We demonstrate that for suitable parameter ranges, the vacuum decay process dominates over the Hawking evaporation process. Finally, we comment on the application of these results to vacuum decay seeded by black holes produced in particle collisions.

  16. Vacuum metastability with black holes

    International Nuclear Information System (INIS)

    Burda, Philipp; Gregory, Ruth; Moss, Ian G. annd

    2015-01-01

    We consider the possibility that small black holes can act as nucleation seeds for the decay of a metastable vacuum, focussing particularly on the Higgs potential. Using a thin-wall bubble approximation for the nucleation process, which is possible when generic quantum gravity corrections are added to the Higgs potential, we show that primordial black holes can stimulate vacuum decay. We demonstrate that for suitable parameter ranges, the vacuum decay process dominates over the Hawking evaporation process. Finally, we comment on the application of these results to vacuum decay seeded by black holes produced in particle collisions.

  17. PDX vacuum vessel stress analysis

    International Nuclear Information System (INIS)

    Nikodem, Z.D.

    1975-01-01

    A stress analysis of PDX vacuum vessel is described and the summary of results is presented. The vacuum vessel is treated as a toroidal shell of revolution subjected to an internal vacuum. The critical buckling pressure is calculated. The effects of the geometrical discontinuity at the juncture of toroidal shell head and cylindrical outside wall, and the concavity of the cylindrical wall are examined. An effect of the poloidal field coil supports and the vessel outside supports on the stress distribution in the vacuum vessel is determined. A method evaluating the influence of circular ports in the vessel wall on the stress level in the vessel is outlined

  18. Vacuum leak detector and method

    Science.gov (United States)

    Edwards, Jr., David

    1983-01-01

    Apparatus and method for detecting leakage in a vacuum system involves a moisture trap chamber connected to the vacuum system and to a pressure gauge. Moisture in the trap chamber is captured by freezing or by a moisture adsorbent to reduce the residual water vapor pressure therein to a negligible amount. The pressure gauge is then read to determine whether the vacuum system is leaky. By directing a stream of carbon dioxide or helium at potentially leaky parts of the vacuum system, the apparatus can be used with supplemental means to locate leaks.

  19. Vacuum science, technology, and applications

    CERN Document Server

    Naik, Pramod K

    2018-01-01

    Vacuum plays an important role in science and technology. The study of interaction of charged particles, neutrals and radiation with each other and with solid surfaces requires a vacuum environment for reliable investigations. Vacuum has contributed immensely to advancements made in nuclear science, space, metallurgy, electrical/electronic technology, chemical engineering, transportation, robotics and many other fields. This book is intended to assist students, scientists, technicians and engineers to understand the basics of vacuum science and technology for application in their projects. The fundamental theories, concepts, devices, applications, and key inventions are discussed.

  20. Surge-damping vacuum valve

    International Nuclear Information System (INIS)

    Bullock, J.C.; Kelley, B.E.

    1977-01-01

    A valve for damping out flow surges in a vacuum system is described. The surge-damping mechanism consists of a slotted, spring-loaded disk adjacent to the valve's vacuum port (the flow passage to the vacuum roughing pump). Under flow surge conditions, the differential pressure forces the disk into a sealing engagement with the vacuum port, thereby restricting the gas flow path to narrow slots in the disk's periphery. The increased flow damps out the flow surge. When pressure is equalized on both sides of the valve, the spring load moves the disk away from the port to restore full flow conductance through the valve

  1. Shiva and Argus target diagnostics vacuum systems

    International Nuclear Information System (INIS)

    Glaros, S.S.; Mayo, S.E.; Campbell, D.; Holeman, D.

    1978-09-01

    The normal operation of LLL's Argus and Shiva laser irradiation facilities demand a main vacuum system for the target chamber and a separate local vacuum system for each of the larger appendage dianostics. This paper will describe the Argus and Shiva main vacuum systems, their respective auxiliary vacuum systems and the individual diagnostics with their respective special vacuum requirements and subsequent vacuum systems. Our latest approach to automatic computer-controlled vacuum systems will be presented

  2. Design and manufacturing of vacuum vessel of TPE-RX

    Energy Technology Data Exchange (ETDEWEB)

    Sago, H.; Kaguchi, H.; Orita, J.; Ishigami, Y. [Mitsubishi Heavy Industries Ltd., Kobe (Japan); Urata, K. [Mitsubishi Heavy Industries Ltd. (Japan). Nuclear Energy Systems Engineering Center; Hasegawa, M. [Mitsubishi Electric Co. (Japan). Nuclear Fusion Development; Yagi, Y.; Hirano, Y.; Shimada, T.; Sekine, S.; Sakakita, H. [Electrotechnical Lab. (Japan)

    1998-07-01

    Construction of a new, large reversed field pinch (RFP) machine called TPE-RX was complete at the end of 1997 as a successor of the previous TPE-1RM20 machine at the Electrotechnical Laboratory (ETL). RFP configuration has been successfully obtained in March 1998. This paper introduces structural design and manufacturing of the vacuum vessel of TPE-RX. The support positions were decided by structural analyses. The structural integrity of the vacuum vessel was evaluated by inelastic analyses. (author)

  3. Design and manufacturing of vacuum vessel of TPE-RX

    International Nuclear Information System (INIS)

    Sago, H.; Kaguchi, H.; Orita, J.; Ishigami, Y.; Urata, K.

    1998-01-01

    Construction of a new, large reversed field pinch (RFP) machine called TPE-RX was complete at the end of 1997 as a successor of the previous TPE-1RM20 machine at the Electrotechnical Laboratory (ETL). RFP configuration has been successfully obtained in March 1998. This paper introduces structural design and manufacturing of the vacuum vessel of TPE-RX. The support positions were decided by structural analyses. The structural integrity of the vacuum vessel was evaluated by inelastic analyses. (author)

  4. Melting the vacuum

    International Nuclear Information System (INIS)

    Rafelski, J.

    1998-01-01

    Results presented at the Quark Matter 97 conference, held in December in Tsukuba, Japan, have provided new insights into the confinement of quarks in matter. The current physics paradigm is that the inertial masses of protons and neutrons, and hence of practically all of the matter around us, originate in the zero-point energy caused by the confinement of quarks inside the small volume of the nucleon. Today, 25 years after Harald Fritzsch, Heinrich Leutwyler and Murray Gell-Mann proposed quantum chromodynamics (QCD) as a means for understanding strongly interacting particles such as nucleons and mesons, our understanding of strong interactions and quark confinement remains incomplete. Quarks and the gluons that bind them together have a ''colour'' charge that may be red, green or blue. But quarks are seen in particles that are white: baryons such as protons and neutrons consist of three quarks with different colour charges, while mesons consist of a quark and an antiquark, and again the colour charge cancels out. To prove that confinement arises from quark-gluon fluctuations in the vacuum that quantum theories dictate exists today, we need to find a way of freeing the colour charge of quarks. Experiments must therefore ''melt'' the vacuum to deconfine quarks and the colour charge. By colliding nuclei at high energies, we hope to produce regions of space filled with free quarks and gluons. This deconfined phase is known as the quark-gluon plasma. At the Tsukuba meeting, Scott Pratt of Michigan State University in the US discussed measurements that show that the hot dense state of matter created in these collisions exists for only 2x10 -23 s. So does the quark gluon plasma exist? No-one doubts that it did at one time, before the vacuum froze into its current state about 20 into the life of the universe, causing the nucleons to form as we know them today. The issue is whether we can recreate this early stage of the universe in laboratory experiments. And if we did

  5. Accelerator vacuum system elements

    International Nuclear Information System (INIS)

    Sivokon', V.V.; Kobets, A.F.; Shvetsov, V.A.; Sivokon', L.V.

    1980-01-01

    Some elements of vacuum systems are investigated. Considerable attention has been given to the investigation into peculiarities in pumping out of a ionoguide for transportation of an accelerated charged particles beam the spread of which often attains a considerable length. The number of pumps over the ionoguide length is experimentally determined. It is shown that as a result of ionoguide warm-up the pumping out time is considerably reduced maximum permissible pressure is decreased by two orders and lesser rate of pump pumping out is required. The investigations have shown that when operating the ionoguide there is no necessity in setting up seals between the ionoguide and magnetodischarged pump. The causes of the phenomenon in which the pressure near the pump is greater than in the end of the ionoguide, are impurities carried in by the pump into the ionoguide volume and the pumping out capacity of the pressure converter

  6. The realm of the vacuum

    International Nuclear Information System (INIS)

    Buchholz, D.; Wanzenberg, R.

    1992-01-01

    The spacelike asymptotic structure of physical states in local quantum theory is analysed. It is shown that this structure can be described in terms of a vacuum state if the theory satisfies a condition of timelike asymptotic abelianess. Theories which violate this condition can have an involved asymptotic vacuum structure as is illustrated by a simple example. (orig.)

  7. Vacuum Technology for Ion Sources

    International Nuclear Information System (INIS)

    Chiggiato, P

    2013-01-01

    The basic notions of vacuum technology for ion sources are presented, with emphasis on pressure profile calculation and choice of pumping technique. A Monte Carlo code (Molflow+) for the evaluation of conductances and the vacuum-electrical analogy for the calculation of time-dependent pressure variations are introduced. The specific case of the Linac4 H - source is reviewed. (author)

  8. ULTRARAPID VACUUM-MICROWAVE HISTOPROCESSING

    NARCIS (Netherlands)

    KOK, LP; BOON, ME

    A novel histoprocessing method for paraffin sections is presented in which the combination of vacuum and microwave exposure is the key element. By exploiting the decrease in boiling temperature under vacuum, the liquid molecules in the tissues have been successfully extracted and exchanged at

  9. Detecting leaks in vacuum bags

    Science.gov (United States)

    Carlstrom, E. E.

    1980-01-01

    Small leaks in vacuum bag can be readily detected by eye, using simple chemical reaction: combination of ammonia and acetic acid vapors to produce cloudy white smoke. Technique has been successfully used to test seam integrity and to identify minute pinholes in vacuum bag used in assembly of ceramic-tile heat shield for Space Shuttle Orbiter.

  10. Vacuum Technology for Superconducting Devices

    Energy Technology Data Exchange (ETDEWEB)

    Chiggiato, P [European Organization for Nuclear Research, Geneva (Switzerland)

    2014-07-01

    The basic notions of vacuum technology for superconducting applications are presented, with an emphasis on mass and heat transport in free molecular regimes. The working principles and practical details of turbomolecular pumps and cryopumps are introduced. The specific case of the Large Hadron Collider’s cryogenic vacuum system is briefly reviewed.

  11. Vacuum Alignment with more Flavors

    DEFF Research Database (Denmark)

    Ryttov, Thomas

    2014-01-01

    We study the alignment of the vacuum in gauge theories with $N_f$ Dirac fermions transforming according to a complex representation of the gauge group. The alignment of the vacuum is produced by adding a small mass perturbation to the theory. We study in detail the $N_f=2,3$ and $4$ case. For $N_...

  12. The AGS Booster vacuum systems

    International Nuclear Information System (INIS)

    Hseuh, H.C.

    1989-01-01

    The AGS Booster is a synchrotron for the acceleration of both protons and heavy ions. The design pressure of low 10 -11 mbar is required to minimize beam loss of the partially stripped heavy ions. To remove contaminants and to reduce outgassing, the vacuum chambers and the components located in them will be chemically cleaned, vacuum fired, baked then treated with nitric oxide. The vacuum sector will be insitu baked to a minimum of 200 degree C and pumped by the combination of sputter ion pumps and titanium sublimation pumps. This paper describes the design and the processing of this ultra high vacuum system, and the performance of some half-cell vacuum chambers. 9 refs., 7 figs

  13. Cosmology with decaying vacuum energy

    International Nuclear Information System (INIS)

    Freese, K.; Adams, F.; Frieman, J.; Mottola, E.

    1987-09-01

    Motivated by recent attempts to solve the cosmological constant problem, we examine the observational consequences of a vacuum energy density which decays in time. For all times later than t ∼ 1 sec, the ratio of the vacuum to the total energy density of the universe must be small. Although the vacuum cannot provide the ''missing mass'' required to close the universe today, its presence earlier in the history of the universe could have important consequences. We discuss restrictions on the vacuum energy arising from primordial nucleosynthesis, the microwave and gamma ray background spectra, and galaxy formation. A small vacuum component at the era of nucleosynthesis, 0.01 5, but in some cases would severely distort the microwave spectrum. 9 refs., 3 figs

  14. Vacuum transitions in dual models

    International Nuclear Information System (INIS)

    Pashnev, A.I.; Volkov, D.V.; Zheltukhin, A.A.

    1976-01-01

    The investigation is continued of the spontaneous vacuum transition problem in the Neview-Schwartz dual model (NSDM). It is shown that vacuum transitions allow disclosing of supplementary degeneration in the resonance state spectrum. The dual amplitudes possess an internal structure corresponding to the presence of an infinite number of quarks with increasing masses and retained charges. The Adler principle holds. Analytic continuation on the constant of induced vacuum transitions makes it possible to establish the existence of spontaneous vacuum transitions in the NSDM. The consequence of this fact is the exact SU(2) symmetry of π, rho meson trajectories and the Higgs mechanism in the model. In this case the ratios of masses of particles leading trajectories are analogous to those obtained in the current algebra. It is shown that in the NSDM there arises chiral SU(2) x SU(2) x U(1) x U(1) x ... symmetry resulting from spontaneous vacuum transitions

  15. Hadron Contribution to Vacuum Polarisation

    CERN Document Server

    Davier, M; Malaescu, B; Zhang, Z

    2016-01-01

    Precision tests of the Standard Theory require theoretical predictions taking into account higher-order quantum corrections. Among these vacuum polarisation plays a predominant role. Vacuum polarisation originates from creation and annihilation of virtual particle–antiparticle states. Leptonic vacuum polarisation can be computed from quantum electrodynamics. Hadronic vacuum polarisation cannot because of the non-perturbative nature of QCD at low energy. The problem is remedied by establishing dispersion relations involving experimental data on the cross section for e+ e− annihilation into hadrons. This chapter sets the theoretical and experimental scene and reviews the progress achieved in the last decades thanks to more precise and complete data sets. Among the various applications of hadronic vacuum polarisation calculations, two are emphasised: the contribution to the anomalous magnetic moment of the muon, and the running of the fine structure constant α to the Z mass scale. They are fundamental ingre...

  16. Some problems of physics of ultrahigh energy cosmic rays

    International Nuclear Information System (INIS)

    Isaev, P.S.

    1999-01-01

    Nearest 15-20 years will be years of flourishing of experimental researches into the energy of cosmic rays at > or ∼ 10 15 eV and of new discoveries in the physics of elementary particles of ultrahigh energies. Unsolved problems of modern physics of ultrahigh energy cosmic rays, which are relevant to the problems of elementary particles physics, are reviewed

  17. Ultrahigh-energy particles from cosmic strings

    International Nuclear Information System (INIS)

    Bhattacharjee, P.

    1991-02-01

    The idea of production of ultrahigh-energy particles in the present universe due to annihilation or collapse of topological defects is discussed. Topological defects, formed in symmetry-breaking phase transitions in the early universe, can survive till today owing to their topological stability. However, under certain circumstances, topological defects may be physically destroyed. When topological defects are destroyed, the energy contained in the defects can be released in the form of massive gauge- and Higgs bosons of the underlying spontaneously broken gauge theory. Subsequent decay of these massive particles can give rise to energetic particles ranging up to an energy on the order of the mass of the original particles released from the defects. This may give us a ''natural'' mechanism of production of extremely energetic cosmic ray particles in the universe today, without the need for any acceleration mechanism. To illustrate this idea, I describe in detail the calculation of the expected ultrahigh-energy proton spectrum due to a specific process which involves collapse or multiple self-intersections of a class of closed cosmic string loops formed in a phase transition at a grand unification energy scale. I discuss the possibility that some of the highest-energy cosmic ray particles are of this origin. By comparing with the observational results on the ultrahigh-energy cosmic rays, we derive an upper limit to the average fraction of the total energy in all ''primary'' cosmic string loops that may be released in the form of particles due to collapse or multiple self-intersections of these loops. No nuclei such as α's or Fe's are in the spectrum. 43 refs., 3 figs

  18. REQUIREMENTS AND GUIDELINES FOR NSLS EXPERIMENTAL BEAM LINE VACUUM SYSTEMS-REVISION B.

    Energy Technology Data Exchange (ETDEWEB)

    FOERSTER,C.

    1999-05-01

    Typical beam lines are comprised of an assembly of vacuum valves and shutters referred to as a ''front end'', optical elements to monochromatize, focus and split the photon beam, and an experimental area where a target sample is placed into the photon beam and data from the interaction is detected and recorded. Windows are used to separate sections of beam lines that are not compatible with storage ring ultra high vacuum. Some experimental beam lines share a common vacuum with storage rings. Sections of beam lines are only allowed to vent up to atmospheric pressure using pure nitrogen gas after a vacuum barrier is established to protect ring vacuum. The front end may only be bled up when there is no current in the machine. This is especially true on the VUV storage ring where for most experiments, windows are not used. For the shorter wavelength, more energetic photons of the x-ray ring, beryllium windows are used at various beam line locations so that the monochromator, mirror box or sample chamber may be used in a helium atmosphere or rough vacuum. The window separates ring vacuum from the environment of the downstream beam line components. The stored beam lifetime in the storage rings and the maintenance of desirable reflection properties of optical surfaces depend upon hydrocarbon-free, ultra-high vacuum systems. Storage ring vacuum systems will operate at pressures of {approximately} 1 x 10{sup {minus}10} Torr without beam and {approximately} 1 x 10{sup {minus}9} Torr with beam. Systems are free of hydrocarbons in the sense that no pumps, valves, etc. containing organics are used. Components are all-metal, chemically cleaned and bakeable. To the extent that beam lines share a common vacuum with the storage ring, the same criteria will hold for beam line components. The design philosophy for NSLS beam lines is to use all-metal, hydrocarbon-free front end components and recommend that experimenters use this approach for common vacuum hardware

  19. REQUIREMENTS AND GUIDELINES FOR NSLS EXPERIMENTAL BEAM LINE VACUUM SYSTEMS-REVISION B

    International Nuclear Information System (INIS)

    FOERSTER, C.

    1999-01-01

    Typical beam lines are comprised of an assembly of vacuum valves and shutters referred to as a ''front end'', optical elements to monochromatize, focus and split the photon beam, and an experimental area where a target sample is placed into the photon beam and data from the interaction is detected and recorded. Windows are used to separate sections of beam lines that are not compatible with storage ring ultra high vacuum. Some experimental beam lines share a common vacuum with storage rings. Sections of beam lines are only allowed to vent up to atmospheric pressure using pure nitrogen gas after a vacuum barrier is established to protect ring vacuum. The front end may only be bled up when there is no current in the machine. This is especially true on the VUV storage ring where for most experiments, windows are not used. For the shorter wavelength, more energetic photons of the x-ray ring, beryllium windows are used at various beam line locations so that the monochromator, mirror box or sample chamber may be used in a helium atmosphere or rough vacuum. The window separates ring vacuum from the environment of the downstream beam line components. The stored beam lifetime in the storage rings and the maintenance of desirable reflection properties of optical surfaces depend upon hydrocarbon-free, ultra-high vacuum systems. Storage ring vacuum systems will operate at pressures of ∼ 1 x 10 -10 Torr without beam and ∼ 1 x 10 -9 Torr with beam. Systems are free of hydrocarbons in the sense that no pumps, valves, etc. containing organics are used. Components are all-metal, chemically cleaned and bakeable. To the extent that beam lines share a common vacuum with the storage ring, the same criteria will hold for beam line components. The design philosophy for NSLS beam lines is to use all-metal, hydrocarbon-free front end components and recommend that experimenters use this approach for common vacuum hardware downstream of front ends. O-ring-sealed valves, if used, are not

  20. Ultrahigh stability of atomically thin metallic glasses

    Energy Technology Data Exchange (ETDEWEB)

    Cao, C. R.; Huang, K. Q.; Zhao, N. J.; Sun, Y. T.; Bai, H. Y.; Gu, L., E-mail: l.gu@iphy.ac.cn, E-mail: dzheng@iphy.ac.cn, E-mail: whw@iphy.ac.cn; Zheng, D. N., E-mail: l.gu@iphy.ac.cn, E-mail: dzheng@iphy.ac.cn, E-mail: whw@iphy.ac.cn; Wang, W. H., E-mail: l.gu@iphy.ac.cn, E-mail: dzheng@iphy.ac.cn, E-mail: whw@iphy.ac.cn [Institute of Physics, Chinese Academy of Sciences, Beijing 100190 (China)

    2014-07-07

    We report the fabrication and study of thermal stability of atomically thin ZrCu-based metallic glass films. The ultrathin films exhibit striking dynamic properties, ultrahigh thermal stability, and unique crystallization behavior with discrete crystalline nanoparticles sizes. The mechanisms for the remarkable high stability and crystallization behaviors are attributed to the dewetting process of the ultrathin film. We demonstrated a promising avenue for understanding some fundamental issues such as glassy structure, crystallization, deformation, and glass formation through atomic resolution imaging of the two dimensional like metallic glasses.

  1. Uses of the vacuum

    International Nuclear Information System (INIS)

    Rohrlich, D.M.

    1986-01-01

    Three problems in quantum field theory are analyzed. Each presents the vacuum in a different role. The connections among these significant roles are discussed in Chapter I. Chapter II contains a calculation of the zero-point energy in the Kaluza-Klein model. The zero-point fluctuations induce a potential which makes the compact dimensional contract. The effective potential is seen to be the four-dimensional version of the Casimir effect. Chapter III contains a Monte Carlo study of asymptotic freedom scales in lattice QCD. Two versions of SU(2) gauge theory, having different representations of the gauge group, are compared. A new method is used to calculate the ratio of scale parameters of the two theories. The method directly uses the weak-coupling behavior of the theories. The Monte-Carlo results are compared with perturbative calculations on the lattice, one of which is presented. They are in good agreement. Chapter IV applies the hypothesis of dimensional reduction to five-dimensional SU(2) and four-dimensional SO(3) lattice gauge theories. New analytic results for the strong- and weak-coupling limits are derived. Monte Carlo calculations show dimensional reduction in the strong coupling phases of both theories. At the phase transition, the two theories show a similar loss of dimensional reduction. An external source of random flux does not induce dimensional reduction where it is not already present

  2. Changing MFTF vacuum environment

    International Nuclear Information System (INIS)

    Margolies, D.; Valby, L.

    1982-01-01

    The Mirror Fusion Test Facility (MFTF) vaccum vessel will be about 60m long and 10m in diameter at the widest point. The allowable operating densities range from 2 x 10 9 to 5 x 10 10 particles per cc. The maximum leak rate of 10 -6 tl/sec is dominated during operation by the deliberately injected cold gas of 250 tl/sec. This gas is pumped by over 1000 square meters of cryopanels, external sorbtion pumps and getters. The design and requirements have changed radically over the past several years, and they are still not in final form. The vacuum system design has also changed, but more slowly and less radically. This paper discusses the engineering effort necessary to meet these stringent and changing requirements. Much of the analysis of the internal systems has been carried out using a 3-D Monte Carlo computer code, which can estimate time dependent operational pressures. This code and its use will also be described

  3. Vacuum type D initial data

    Science.gov (United States)

    García-Parrado Gómez-Lobo, Alfonso

    2016-09-01

    A vacuum type D initial data set is a vacuum initial data set of the Einstein field equations whose data development contains a region where the space–time is of Petrov type D. In this paper we give a systematic characterisation of a vacuum type D initial data set. By systematic we mean that the only quantities involved are those appearing in the vacuum constraints, namely the first fundamental form (Riemannian metric) and the second fundamental form. Our characterisation is a set of conditions consisting of the vacuum constraints and some additional differential equations for the first and second fundamental forms These conditions can be regarded as a system of partial differential equations on a Riemannian manifold and the solutions of the system contain all possible regular vacuum type D initial data sets. As an application we particularise our conditions for the case of vacuum data whose data development is a subset of the Kerr solution. This has applications in the formulation of the nonlinear stability problem of the Kerr black hole.

  4. Investigation of Vacuum Insulator Surface Dielectric Strength with Nanosecond Pulses

    International Nuclear Information System (INIS)

    Nunnally, W.C.; Krogh, M.; Williams, C.; Trimble, D.; Sampayan, S.; Caporaso, G.

    2003-01-01

    The maximum vacuum insulator surface dielectric strength determines the acceleration electric field gradient possible in a short pulse accelerator. Previous work has indicated that higher electric field strengths along the insulator-vacuum interface might be obtained as the pulse duration is decreased. In this work, a 250 kV, single ns wide impulse source was applied to small diameter, segmented insulators samples in a vacuum to evaluate the multi-layer surface dielectric strength of the sample construction. Resonances in the low inductance test geometry were used to obtain unipolar, pulsed electric fields in excess of 100 MV/m on the insulator surface. The sample construction, experimental arrangement and experimental results are presented for the initial data in this work. Modeling of the multi-layer structure is discussed and methods of improving insulator surface dielectric strength in a vacuum are proposed

  5. Vacuum vessel for thermonuclear device

    International Nuclear Information System (INIS)

    Hagiwara, Koji; Imura, Yasuya.

    1979-01-01

    Purpose: To provide constituted method for easily performing baking of vacuum vessel, using short-circuiting segments. Constitution: At the time of baking, one turn circuit is formed by the vacuum vessel and short-circuiting segments, and current transformer converting the one turn circuit into a secondary circuit by the primary coil and iron core is formed, and the vacuum vessel is Joule heated by an induction current from the primary coil. After completion of baking, the short-circuiting segments are removed. (Kamimura, M.)

  6. Vacuum system for HIMAC synchrotrons

    International Nuclear Information System (INIS)

    Kanazawa, M.; Sudou, M.; Sato, K.

    1994-01-01

    HIMAC synchrotrons are now under construction, which require vacuum chambers of large aperture and high vacuum of about 10 -9 torr. Wide thin wall vacuum chamber of 0.3 mm thickness reinforced with ribs has been developed as the chamber at dipole magnet. We have just now started to evacuate the lower ring. The obtained average value was about 5x10 -8 torr with turbo-molecular and sputter ion pumps, and 1.1x10 -9 torr after baking. (author)

  7. The localized quantum vacuum field

    International Nuclear Information System (INIS)

    Dragoman, D

    2008-01-01

    A model for the localized quantum vacuum is proposed in which the zero-point energy (ZPE) of the quantum electromagnetic field originates in energy- and momentum-conserving transitions of material systems from their ground state to an unstable state with negative energy. These transitions are accompanied by emissions and re-absorptions of real photons, which generate a localized quantum vacuum in the neighborhood of material systems. The model could help resolve the cosmological paradox associated with the ZPE of electromagnetic fields, while reclaiming quantum effects associated with quantum vacuum such as the Casimir effect and the Lamb shift. It also offers a new insight into the Zitterbewegung of material particles

  8. The localized quantum vacuum field

    Energy Technology Data Exchange (ETDEWEB)

    Dragoman, D [Physics Department, University of Bucharest, PO Box MG-11, 077125 Bucharest (Romania)], E-mail: danieladragoman@yahoo.com

    2008-03-15

    A model for the localized quantum vacuum is proposed in which the zero-point energy (ZPE) of the quantum electromagnetic field originates in energy- and momentum-conserving transitions of material systems from their ground state to an unstable state with negative energy. These transitions are accompanied by emissions and re-absorptions of real photons, which generate a localized quantum vacuum in the neighborhood of material systems. The model could help resolve the cosmological paradox associated with the ZPE of electromagnetic fields, while reclaiming quantum effects associated with quantum vacuum such as the Casimir effect and the Lamb shift. It also offers a new insight into the Zitterbewegung of material particles.

  9. Resistor cooling in a vacuum

    International Nuclear Information System (INIS)

    Crittenden, R.; Krider, J.

    1987-01-01

    This note describes thermal measurements which were done on a resistor operating both in air at one atmosphere pressure and in a vacuum of a few milliTorr. The motivation for this measurement was our interest in operating a BGO crystal-photomultiplier tube-base assembly in a vacuum, as a synchrotron radiation detector to tag electrons in the MT beam. We wished to determine what fraction of the total resistor power was dissipated by convection in air, in order to know whether there would be excessive heating of the detector assembly in a vacuum. 3 figs

  10. Experimental tests of vacuum energy

    CERN Multimedia

    CERN. Geneva

    2015-01-01

    While the current vacuum energy of the Universe is very small, in our standard cosmological picture it has been much larger at earlier epochs. We try to address the question of what are possible ways to try to experimentally verify this. One direction is to look for systems where vacuum energy constitutes a non-negligible fraction of the total energy, and study the properties of those. Another possibility is to focus on the epochs around cosmic phase transitions, when the vacuum energy is of the same order as the total energy. Along these lines we investigate properties of neutron stars and the imprint of phase transitions on primordial gravitational waves.

  11. Vacuum arc ion charge state distributions

    International Nuclear Information System (INIS)

    Brown, I.G.; Godechot, X.

    1990-06-01

    We have measured vacuum arc ion charge state spectra for a wide range of metallic cathode materials. The charge state distributions were measured using a time-of-flight diagnostic to monitor the energetic ion beam produced by a metal vapor vacuum arc ion source. We have obtained data for 48 metallic cathode elements: Li, C, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ge, Sr, Y, Zr, Nb, Mo, Pd, Ag, Cd, In, Sn, Ba, La, Ce, Pr, Nd, Sm, Gd, Dy, Ho, Er, Yb, Hf, Ta, W, Ir, Pt, Au, Pb, Bi, Th and U. The arc was operated in a pulsed mode with pulse length 0.25 msec; arc current was 100 A throughout. This array of elements extends and completes previous work by us. In this paper the measured distributions are cataloged and compared with our earlier results and with those of other workers. We also make some observations about the performance of the various elements as suitable vacuum arc cathode materials

  12. Vacuum arc ion charge-state distributions

    International Nuclear Information System (INIS)

    Brown, I.G.; Godechot, X.

    1991-01-01

    The authors have measured vacuum arc ion charge-state spectra for a wide range of metallic cathode materials. The charge-state distributions were measured using a time-of-flight diagnostic to monitor the energetic ion beam produced by a metal vapor vacuum arc ion source. They have obtained data for 48 metallic cathode elements: Li, C, Mg, Al, Si, Ca, Sc, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ge, Sr, Y, Zr, Nb, Mo, Pd, Ag, Cd, In, Sn, Ba, La, Ce, Pr, Nd, Sm, Gd, Dy, Ho, Er, Yb, Hf, Ta, W, Ir, Pt, Au, Pb, Bi, Th, and U. The arc was operated in a pulsed mode with pulse length 0.25 ms; arc current was 100 A throughout. This array of elements extends and completes previous work by the authors. In this paper the measured distributions are cataloged and compared with their earlier results and those of other workers. They also make some observations about the performance of the various elements as suitable vacuum arc cathode materials

  13. Vacuum switchgear for power station auxiliary switchboards

    International Nuclear Information System (INIS)

    Coombs, P.E.

    1992-01-01

    Sizewell B is the first UK power station in which vacuum switchgear is used for the auxiliary switchboards. Previously the 3.3kV, 6.6kV or 11kV switchgear has used air-break circuit breakers and fused air-break contactors, known as motor starting devices or fused switching devices (FSD). The use of vacuum interrupters is therefore a new technology in this application, although it has been established in the UK distribution network and in industrial installations from the mid 1970s. Vacuum switchgear was already in use in the USA for power station auxiliary switchgear at the time that it was proposed for Sizewell B. The Sizewell B high voltage auxiliary switchgear comprises eight Unit and Station Auxiliary Switchboards at 3.3kV and 11kV, and four 3.3kV Essential Switchboards for the essential safety related circuits, making a total of 65 circuit breakers plus FSD panels. (Author)

  14. NCSX Vacuum Vessel Fabrication

    International Nuclear Information System (INIS)

    Viola ME; Brown T; Heitzenroeder P; Malinowski F; Reiersen W; Sutton L; Goranson P; Nelson B; Cole M; Manuel M; McCorkle D.

    2005-01-01

    The National Compact Stellarator Experiment (NCSX) is being constructed at the Princeton Plasma Physics Laboratory (PPPL) in conjunction with the Oak Ridge National Laboratory (ORNL). The goal of this experiment is to develop a device which has the steady state properties of a traditional stellarator along with the high performance characteristics of a tokamak. A key element of this device is its highly shaped Inconel 625 vacuum vessel. This paper describes the manufacturing of the vessel. The vessel is being fabricated by Major Tool and Machine, Inc. (MTM) in three identical 120 o vessel segments, corresponding to the three NCSX field periods, in order to accommodate assembly of the device. The port extensions are welded on, leak checked, cut off within 1-inch of the vessel surface at MTM and then reattached at PPPL, to accommodate assembly of the close-fitting modular coils that surround the vessel. The 120 o vessel segments are formed by welding two 60 o segments together. Each 60 o segment is fabricated by welding ten press-formed panels together over a collapsible welding fixture which is needed to precisely position the panels. The vessel is joined at assembly by welding via custom machined 8-inch (20.3 cm) wide spacer ''spool pieces''. The vessel must have a total leak rate less than 5 X 10 -6 t-l/s, magnetic permeability less than 1.02(micro), and its contours must be within 0.188-inch (4.76 mm). It is scheduled for completion in January 2006

  15. Particle creation during vacuum decay

    International Nuclear Information System (INIS)

    Rubakov, V.A.

    1984-01-01

    The hamiltonian approach is developed with regard to the problem of particle creation during the tunneling process, leading to the decay of the false vacuum in quantum field theory. It is shown that, to the lowest order in (h/2π), the particle creation is described by the euclidean Schroedinger equation in an external field of a bounce. A technique for solving this equation is developed in an analogy to the Bogoliubov transformation technique, in the theory of particle creation in the presence of classical background fields. The technique is illustrated by two examples, namely, the particle creation during homogeneous vacuum decay and during the tunneling process leading to the materialization of the thin-wall bubble of a new vacuum in the metastable one. The curious phenomenon of intensive particle annihilation during vacuum decay is discussed and explicitly illustrated within the former example. The non-unitary extension of the Bogoliubov u, v transformations is described in the appendix. (orig.)

  16. Vacuum in intensive gauge fields

    International Nuclear Information System (INIS)

    Matinian, S.G.

    1977-12-01

    The behaviour of vacuum in a covariantly constant Yang-Mills field is considered. The expressions for the effective Lagrangian in an intensive field representing the asymptotic freedom of the theory are found

  17. Utilizing scalar electromagnetics to tap vacuum energy

    International Nuclear Information System (INIS)

    Sweet, F.; Bearden, T.E.

    1991-01-01

    Based on E.T. Whittaker's previously unnoticed 1903-1904 papers which established a hidden bidirectional EM wave structure in a standing forcefield free scalar potential, a method of directly engineering the ambient potential of the vacuum has been developed and realized experimentally. Adding Whittaker's engineerable hidden variable theory to classical electromagnetic, quantum mechanics, and general relativity produces supersets of each discipline. These supersets are joined by the common Whittaker subset, producing a unified field theory that is engineerable and tested. By treating the nucleus of the atom as a pumped phase conjugate mirror, several working model energy units have been produced which excite and organize the local vacuum, increase the local virtual photon flux between local vacuum and nucleus, establish coherent self-oscillations between the local excited vacuum and the affected nuclei, utilized the self-oscillating standing wave for self-pumping of the nuclei/mirrors, introduce a very tiny signal wave to the mirrors, and output into an external load circuit a powerful, amplified, time-reversed phase conjugate replica wave at 60 Hertz frequency and nominal 120 volt sine wave power. Several models have been built, ranging from 6 watts early on to one of 5 kilowatts. Both closed battery-less systems with damped positive feedback and open loop systems with battery-powered input have been successfully built. Open loop power gains of from 5 x 10 4 to 1.5 x 10 6 have been achieved. Antigravity experiments have also been successfully conducted where the weight of the unit was reduced by 90% in controlled experiments, with a signal wave input of 175 microwatts and an output of 1 kilowatt. The basic theory of the device is briefly explained and experimental results presented

  18. Vacuum production; Produccion de vacio

    Energy Technology Data Exchange (ETDEWEB)

    Segovia, J. L. de

    2010-07-01

    Since the advent of ultra high vacuum in 1958 has been a great demand for new as means of production and to meet the process needs to be done: industry heavy, high technology and space research areas, large accelerator systems particles or nuclear fusion. In this paper we explore the modern media production: dry vacuum pumps, turbo pumps, pump status diffusion ion pumps and cryopumps. (Author)

  19. Development of vacuum brazing furnace

    International Nuclear Information System (INIS)

    Singh, Rajvir; Yedle, Kamlesh; Jain, A.K.

    2005-01-01

    In joining of components where welding process is not possible brazing processes are employed. Value added components, high quality RF systems, UHV components of high energy accelerators, carbide tools etc. are produced using different types of brazing methods. Furnace brazing under vacuum atmosphere is the most popular and well accepted method for production of the above mentioned components and systems. For carrying out vacuum brazing successfully it is essential to have a vacuum brazing furnace with latest features of modern vacuum brazing technology. A vacuum brazing furnace has been developed and installed for carrying out brazing of components of copper, stainless steel and components made of dissimilar metals/materials. The above furnace has been designed to accommodate jobs of 700mm diameter x 2000mm long sizes with job weight of 500kgs up to a maximum temperature of 1250 degC at a vacuum of 5 x 10 -5 Torr. Oil diffusion pumping system with a combination of rotary and mechanical booster pump have been employed for obtaining vacuum. Molybdenum heating elements, radiation shield of molybdenum and Stainless Steel Grade 304 have been used. The above furnace is computer controlled with manual over ride facility. PLC and Pentium PC are integrated together to maneuver steps of operation and safety interlocks of the system. Closed loop water supply provides cooling to the system. The installation of the above system is in final stage of completion and it will be ready for use in next few months time. This paper presents insights of design and fabrication of a modern vacuum brazing furnace and its sub-system. (author)

  20. Vacuum energy from noncommutative models

    Science.gov (United States)

    Mignemi, S.; Samsarov, A.

    2018-04-01

    The vacuum energy is computed for a scalar field in a noncommutative background in several models of noncommutative geometry. One may expect that the noncommutativity introduces a natural cutoff on the ultraviolet divergences of field theory. Our calculations show however that this depends on the particular model considered: in some cases the divergences are suppressed and the vacuum energy is only logarithmically divergent, in other cases they are stronger than in the commutative theory.

  1. ITER diagnostic system: Vacuum interface

    International Nuclear Information System (INIS)

    Patel, K.M.; Udintsev, V.S.; Hughes, S.; Walker, C.I.; Andrew, P.; Barnsley, R.; Bertalot, L.; Drevon, J.M.; Encheva, A.; Kashchuk, Y.; Maquet, Ph.; Pearce, R.; Taylor, N.; Vayakis, G.; Walsh, M.J.

    2013-01-01

    Diagnostics play an essential role for the successful operation of the ITER tokamak. They provide the means to observe control and to measure plasma during the operation of ITER tokamak. The components of the diagnostic system in the ITER tokamak will be installed in the vacuum vessel, in the cryostat, in the upper, equatorial and divertor ports, in the divertor cassettes and racks, as well as in various buildings. Diagnostic components that are placed in a high radiation environment are expected to operate for the life of ITER. There are approx. 45 diagnostic systems located on ITER. Some diagnostics incorporate direct or independently pumped extensions to maintain their necessary vacuum conditions. They require a base pressure less than 10 −7 Pa, irrespective of plasma operation, and a leak rate of less than 10 −10 Pa m 3 s −1 . In all the cases it is essential to maintain the ITER closed fuel cycle. These directly coupled diagnostic systems are an integral part of the ITER vacuum containment and are therefore subject to the same design requirements for tritium and active gas confinement, for all normal and accidental conditions. All the diagnostics, whether or not pumped, incorporate penetration of the vacuum boundary (i.e. window assembly, vacuum feedthrough etc.) and demountable joints. Monitored guard volumes are provided for all elements of the vacuum boundary that are judged to be vulnerable by virtue of their construction, material, load specification etc. Standard arrangements are made for their construction and for the monitoring, evacuating and leak testing of these volumes. Diagnostic systems are incorporated at more than 20 ports on ITER. This paper will describe typical and particular arrangements of pumped diagnostic and monitored guard volume. The status of the diagnostic vacuum systems, which are at the start of their detailed design, will be outlined and the specific features of the vacuum systems in ports and extensions will be described

  2. ITER diagnostic system: Vacuum interface

    Energy Technology Data Exchange (ETDEWEB)

    Patel, K.M., E-mail: Kaushal.Patel@iter.org [ITER Organization, Route de Vinon sur Verdon, 13115 St Paul-Lez-Durance (France); Udintsev, V.S.; Hughes, S.; Walker, C.I.; Andrew, P.; Barnsley, R.; Bertalot, L. [ITER Organization, Route de Vinon sur Verdon, 13115 St Paul-Lez-Durance (France); Drevon, J.M. [Bertin Technologies, BP 22, 13762 Aix-en Provence cedex 3 (France); Encheva, A. [ITER Organization, Route de Vinon sur Verdon, 13115 St Paul-Lez-Durance (France); Kashchuk, Y. [Institution “PROJECT CENTER ITER”, 1, Akademika Kurchatova pl., Moscow (Russian Federation); Maquet, Ph. [Bertin Technologies, BP 22, 13762 Aix-en Provence cedex 3 (France); Pearce, R.; Taylor, N.; Vayakis, G.; Walsh, M.J. [ITER Organization, Route de Vinon sur Verdon, 13115 St Paul-Lez-Durance (France)

    2013-10-15

    Diagnostics play an essential role for the successful operation of the ITER tokamak. They provide the means to observe control and to measure plasma during the operation of ITER tokamak. The components of the diagnostic system in the ITER tokamak will be installed in the vacuum vessel, in the cryostat, in the upper, equatorial and divertor ports, in the divertor cassettes and racks, as well as in various buildings. Diagnostic components that are placed in a high radiation environment are expected to operate for the life of ITER. There are approx. 45 diagnostic systems located on ITER. Some diagnostics incorporate direct or independently pumped extensions to maintain their necessary vacuum conditions. They require a base pressure less than 10{sup −7} Pa, irrespective of plasma operation, and a leak rate of less than 10{sup −10} Pa m{sup 3} s{sup −1}. In all the cases it is essential to maintain the ITER closed fuel cycle. These directly coupled diagnostic systems are an integral part of the ITER vacuum containment and are therefore subject to the same design requirements for tritium and active gas confinement, for all normal and accidental conditions. All the diagnostics, whether or not pumped, incorporate penetration of the vacuum boundary (i.e. window assembly, vacuum feedthrough etc.) and demountable joints. Monitored guard volumes are provided for all elements of the vacuum boundary that are judged to be vulnerable by virtue of their construction, material, load specification etc. Standard arrangements are made for their construction and for the monitoring, evacuating and leak testing of these volumes. Diagnostic systems are incorporated at more than 20 ports on ITER. This paper will describe typical and particular arrangements of pumped diagnostic and monitored guard volume. The status of the diagnostic vacuum systems, which are at the start of their detailed design, will be outlined and the specific features of the vacuum systems in ports and extensions

  3. Renormalized vacuum polarization for finite range potentials

    International Nuclear Information System (INIS)

    Lewin, J.D.

    1975-10-01

    This report presents computed vacuum polarization effects for leptons in a spherical potential well of radius large compared with the lepton Compton wavelength. These results, together with those previously obtained for small radius wells, show that the total charge generated is independent of well radius and lepton mass; thus the quadratic divergence obtained for the total unrenormalized charge can be removed by the subtraction of the contribution computed for a lepton of mass M(→ infinity) as in the case of the Coulomb potential. Various other problems arising from the earlier study are clarified by the present results. (author)

  4. Technical specification for vacuum systems

    International Nuclear Information System (INIS)

    Khaw, J.

    1987-01-01

    The vacuum systems at the Stanford Linear Accelerator Center (SLAC) are primarily of all-metal construction and operate at pressures from 10 -5 to 10 -11 Torr. The primary gas loads during operation result from thermal desorption and beam-induced desorption from the vacuum chamber walls. These desorption rates can be extremely high in the case of hydrocarbons and other contaminants. These specifications place a major emphasis on eliminating contamination sources. The specifications and procedures have been written to insure the cleanliness and vacuum integrity of all SLAC vacuum systems, and to assist personnel involved with SLAC vacuum systems in choosing and designing components that are compatible with existing systems and meet the quality and reliability of SLAC vacuum standards. The specification includes requirements on design, procurement, fabrication, chemical cleaning, clean room practices, welding and brazing, helium leak testing, residual gas analyzer testing, bakeout, venting, and pumpdown. Also appended are specifications regarding acceptable vendors, isopropyl alcohol, bakeable valve cleaning procedure, mechanical engineering safety inspection, notes on synchrotron radiation, and specifications of numerous individual components

  5. Vacuum vessel for thermonuclear device

    International Nuclear Information System (INIS)

    Kikuchi, Mitsuru; Kurita, Gen-ichi; Onozuka, Masaki; Suzuki, Masaru.

    1997-01-01

    Heat of inner walls of a vacuum vessel that receive radiation heat from plasmas by way of first walls is removed by a cooling medium flowing in channels for cooling the inner walls. Nuclear heat generation of constitutional materials of the vacuum vessel caused by fast neutrons and γ rays is removed by a cooling medium flowing in cooling channels disposed in the vacuum vessel. Since the heat from plasmas and the nuclear heat generation are removed separately, the amount of the cooling medium flowing in the channels for cooling inner walls is increased for cooling a great amount of heat from plasmas while the amount of the cooling medium flowing in the channels for cooling the inside of the vacuum vessel is reduced for cooling the small amount of nuclear heat generation. Since the amount of the cooling medium can thus be optimized, the capacity of the facilities for circulating the cooling medium can be reduced. In addition, since the channels for cooling the inner walls and the channels of cooling medium formed in the vacuum vessel are disposed to the inner walls of the vacuum vessel on the side opposite to plasmas, integrity of the channels relative to leakage of the cooling medium can be ensured. (N.H.)

  6. Vacuum vessel for thermonuclear device

    Energy Technology Data Exchange (ETDEWEB)

    Kikuchi, Mitsuru; Kurita, Gen-ichi [Japan Atomic Energy Research Inst., Tokyo (Japan); Onozuka, Masaki; Suzuki, Masaru

    1997-07-31

    Heat of inner walls of a vacuum vessel that receive radiation heat from plasmas by way of first walls is removed by a cooling medium flowing in channels for cooling the inner walls. Nuclear heat generation of constitutional materials of the vacuum vessel caused by fast neutrons and {gamma} rays is removed by a cooling medium flowing in cooling channels disposed in the vacuum vessel. Since the heat from plasmas and the nuclear heat generation are removed separately, the amount of the cooling medium flowing in the channels for cooling inner walls is increased for cooling a great amount of heat from plasmas while the amount of the cooling medium flowing in the channels for cooling the inside of the vacuum vessel is reduced for cooling the small amount of nuclear heat generation. Since the amount of the cooling medium can thus be optimized, the capacity of the facilities for circulating the cooling medium can be reduced. In addition, since the channels for cooling the inner walls and the channels of cooling medium formed in the vacuum vessel are disposed to the inner walls of the vacuum vessel on the side opposite to plasmas, integrity of the channels relative to leakage of the cooling medium can be ensured. (N.H.)

  7. Monte Carlo simulations of ultra high vacuum and synchrotron radiation for particle accelerators

    CERN Document Server

    AUTHOR|(CDS)2082330; Leonid, Rivkin

    With preparation of Hi-Lumi LHC fully underway, and the FCC machines under study, accelerators will reach unprecedented energies and along with it very large amount of synchrotron radiation (SR). This will desorb photoelectrons and molecules from accelerator walls, which contribute to electron cloud buildup and increase the residual pressure - both effects reducing the beam lifetime. In current accelerators these two effects are among the principal limiting factors, therefore precise calculation of synchrotron radiation and pressure properties are very important, desirably in the early design phase. This PhD project shows the modernization and a major upgrade of two codes, Molflow and Synrad, originally written by R. Kersevan in the 1990s, which are based on the test-particle Monte Carlo method and allow ultra-high vacuum and synchrotron radiation calculations. The new versions contain new physics, and are built as an all-in-one package - available to the public. Existing vacuum calculation methods are overvi...

  8. The chirped-pulse inverse free-electron laser: A high-gradient vacuum laser accelerator

    International Nuclear Information System (INIS)

    Hartemann, F.V.; Landahl, E.C.; Troha, A.L.; Van Meter, J.R.; Baldis, H.A.; Freeman, R.R.; Luhmann, N.C. Jr.; Song, L.; Kerman, A.K.; Yu, D.U.

    1999-01-01

    The inverse free-electron laser (IFEL) interaction is studied theoretically and computationally in the case where the drive laser intensity approaches the relativistic regime, and the pulse duration is only a few optical cycles long. The IFEL concept has been demonstrated as a viable vacuum laser acceleration process; it is shown here that by using an ultrashort, ultrahigh-intensity drive laser pulse, the IFEL interaction bandwidth and accelerating gradient are increased considerably, thus yielding large energy gains. Using a chirped pulse and negative dispersion focusing optics allows one to take further advantage of the laser optical bandwidth and produce a chromatic line focus maximizing the gradient. The combination of these novel ideas results in a compact vacuum laser accelerator capable of accelerating picosecond electron bunches with a high gradient (GeV/m) and very low energy spread. copyright 1999 American Institute of Physics

  9. Vacuum Simulations in High Energy Accelerators and Distribution Properties of Continuous and Discrete Particle Motions

    CERN Document Server

    Aichinger, Ida; Kersevan, Roberto

    The underlying thesis on mathematical simulation methods in application and theory is structured into three parts. The first part sets up a mathematical model capable of predicting the performance and operation of an accelerator’s vacuum system based on analytical methods. A coupled species-balance equation system describes the distribution of the gas dynamics in an ultra-high vacuum system considering impacts of conductance limitations, beam induced effects (ion-, electron-, and photon-induced de- sorption), thermal outgassing and sticking probabilities of the chamber materials. A new solving algorithm based on sparse matrix representations, is introduced and presents a closed form solution of the equation system. The model is implemented in a Python environment, named PyVasco, and is supported by a graphical user interface to make it easy available for everyone. A sensitivity analysis, a cross-check with the Test-Particle Monte Carlo simulation program Molflow+ and a comparison of the simulation results t...

  10. Flipped cryptons and ultrahigh energy cosmic rays

    CERN Document Server

    Ellis, Jonathan Richard; Nanopoulos, D V

    2004-01-01

    Cryptons are metastable bound states of fractionally-charged particles that arise generically in the hidden sectors of models derived from heterotic string. We study their properties and decay modes in a specific flipped SU(5) model with long-lived four-particle spin-zero bound states called tetrons. We show that the neutral tetrons are metastable, and exhibit the tenth order nonrenormalizable superpotential operators responsible for their dominant decays. By analogy with QCD, we expect charged tetrons to be somewhat heavier, and to decay relatively rapidly via lower-order interactions that we also exhibit. The expected masses and lifetimes of the neutral tetrons make them good candidates for cold dark matter, and a potential source of the ultrahigh energy cosmic rays which have been observed, whereas the charged tetrons would have decayed in the early Universe.

  11. Plasma mirrors for ultrahigh-intensity optics

    International Nuclear Information System (INIS)

    Thaury, C.; Quere, F.; Levy, A.; Ceccotti, T.; Monot, P.; Bougeard, M.; Reau, F.; D'Oliveira, P.; Martin, PH.; Geindre, J.P.; Audebert, P.; Marjoribanks, R.; Marjoribanks, R.

    2007-01-01

    Specular reflection is one of the most fundamental processes of optics. At moderate light intensities generated by conventional light sources this process is well understood. But at those capable of being produced by modern ultrahigh-intensity lasers, many new and potentially useful phenomena arise. When a pulse from such a laser hits an optically polished surface, it generates a dense plasma that itself acts as a mirror, known as a plasma mirror (PM). PMs do not just reflect the remainder of the incident beam, but can act as active optical elements. Using a set of three consecutive PMs in different regimes, we significantly improve the temporal contrast of femtosecond pulses, and demonstrate that high-order harmonics of the laser frequency can be generated through two distinct mechanisms. A better understanding of these processes should aid the development of laser-driven atto-second sources for use in fields from materials science to molecular biology. (authors)

  12. Ultrahigh humidity sensitivity of graphene oxide.

    Science.gov (United States)

    Bi, Hengchang; Yin, Kuibo; Xie, Xiao; Ji, Jing; Wan, Shu; Sun, Litao; Terrones, Mauricio; Dresselhaus, Mildred S

    2013-01-01

    Humidity sensors have been extensively used in various fields, and numerous problems are encountered when using humidity sensors, including low sensitivity, long response and recovery times, and narrow humidity detection ranges. Using graphene oxide (G-O) films as humidity sensing materials, we fabricate here a microscale capacitive humidity sensor. Compared with conventional capacitive humidity sensors, the G-O based humidity sensor has a sensitivity of up to 37800% which is more than 10 times higher than that of the best one among conventional sensors at 15%-95% relative humidity. Moreover, our humidity sensor shows a fast response time (less than 1/4 of that of the conventional one) and recovery time (less than 1/2 of that of the conventional one). Therefore, G-O appears to be an ideal material for constructing humidity sensors with ultrahigh sensitivity for widespread applications.

  13. Plasma mirrors for ultrahigh-intensity optics

    Energy Technology Data Exchange (ETDEWEB)

    Thaury, C; Quere, F; Levy, A; Ceccotti, T; Monot, P; Bougeard, M; Reau, F; D' Oliveira, P; Martin, PH [CEA, DSM, DRECAM, Serv Photons Atomes and Mol, F-91191 Gif Sur Yvette, (France); Geindre, J P; Audebert, P [Ecole Polytech, CNRS, Lab Utilisat Lasers Inst, F-91128 Palaiseau, (France); Marjoribanks, R [Univ Toronto, Dept Phys, Toronto, ON M5S 1A7, (Canada); Marjoribanks, R [Univ Toronto, Inst Opt Sci, Toronto, ON M5S 1A7, (Canada)

    2007-07-01

    Specular reflection is one of the most fundamental processes of optics. At moderate light intensities generated by conventional light sources this process is well understood. But at those capable of being produced by modern ultrahigh-intensity lasers, many new and potentially useful phenomena arise. When a pulse from such a laser hits an optically polished surface, it generates a dense plasma that itself acts as a mirror, known as a plasma mirror (PM). PMs do not just reflect the remainder of the incident beam, but can act as active optical elements. Using a set of three consecutive PMs in different regimes, we significantly improve the temporal contrast of femtosecond pulses, and demonstrate that high-order harmonics of the laser frequency can be generated through two distinct mechanisms. A better understanding of these processes should aid the development of laser-driven atto-second sources for use in fields from materials science to molecular biology. (authors)

  14. Spherical collapse model in time varying vacuum cosmologies

    International Nuclear Information System (INIS)

    Basilakos, Spyros; Plionis, Manolis; Sola, Joan

    2010-01-01

    We investigate the virialization of cosmic structures in the framework of flat Friedmann-Lemaitre-Robertson-Walker cosmological models, in which the vacuum energy density evolves with time. In particular, our analysis focuses on the study of spherical matter perturbations, as they decouple from the background expansion, 'turn around', and finally collapse. We generalize the spherical collapse model in the case when the vacuum energy is a running function of the Hubble rate, Λ=Λ(H). A particularly well-motivated model of this type is the so-called quantum field vacuum, in which Λ(H) is a quadratic function, Λ(H)=n 0 +n 2 H 2 , with n 0 ≠0. This model was previously studied by our team using the latest high quality cosmological data to constrain its free parameters, as well as the predicted cluster formation rate. It turns out that the corresponding Hubble expansion history resembles that of the traditional ΛCDM cosmology. We use this Λ(t)CDM framework to illustrate the fact that the properties of the spherical collapse model (virial density, collapse factor, etc.) depend on the choice of the considered vacuum energy (homogeneous or clustered). In particular, if the distribution of the vacuum energy is clustered, then, under specific conditions, we can produce more concentrated structures with respect to the homogeneous vacuum energy case.

  15. Lanthanum additions and the toughness of ultra-high strength steels and the determination of appropriate lanthanum additions

    International Nuclear Information System (INIS)

    Garrison, Warren M.; Maloney, James L.

    2005-01-01

    Studies of commercial heats of AF1410 steel suggest that under appropriate conditions additions of rare-earth elements can significantly enhance fracture toughness. This improvement in toughness is not due to an extremely low inclusion volume fraction but is apparently due to the formation of larger and more widely spaced inclusions. The purpose of this work is to discuss our experience in using rare-earth additions to laboratory scale vacuum induction melted and subsequently vacuum arc remelted heats of ultra-high strength steels to achieve inclusion distributions similar to those observed in commercial heats modified with lanthanum additions. The results indicate that lanthanum additions of 0.015 wt.% to low sulfur steels which have been well deoxidized using carbon-vacuum deoxidation can result in lanthanum rich inclusions which are similar in size, volume fraction and spacing to those obtained in commercially produced heats of ultra-high strength steel to which lanthanum has been added. The heat of steel to which lanthanum additions of 0.015 wt.% were made had significantly higher toughness than did the heat of the same steel in which the sulfur had been gettered as small and closely spaced particles of MnS and which had an inclusion volume fraction similar to that of the heat modified by the addition of 0.015 wt.% lanthanum. This improvement in toughness was attributed to an increase in inclusion spacing. An addition of 0.06 wt.% lanthanum was excessive. Such an addition of lanthanum resulted in a huge volume fraction of large cuboidal inclusions which primarily contain lanthanum and oxygen and which are extremely detrimental to toughness

  16. Numerical study on the performance of vacuum cooler and evaporation-boiling phenomena during vacuum cooling of cooked meat

    International Nuclear Information System (INIS)

    Jin, T.X.; Xu, L.

    2006-01-01

    The vacuum cooling of cooked meats is described in this paper. Based on the energy and mass balance, a modified mathematical model based on a previous model is developed to analyze the performance of the vacuum cooler and the evaporation-boiling phenomena during vacuum cooling of cooked meat. Validation experimentation is performed in the designed vacuum cooler. Boiling occurs inside the cooked meat. There is a boiling front, and the boiling front moves toward the center of the cooked meat as the vacuum cooling proceeds. The experimental data are compared with the simulation results. It is found that the differences of the temperature between the simulation and the experimentation are within 5 deg. C, and the deviation of weight loss between the simulation and the experimentation is within 4%. The simulation results agree with the experimental data well. The modified model can be used to predict the variation of the vacuum pressure in the chamber, the temperature and pressure distributions and the weight loss profiles of cylindrical cooked meats

  17. Ultrahigh pressure deformation of polycrystaline hcp-cobalt

    Science.gov (United States)

    Merkel, S.; Antonangeli, D.; Fiquet, G.; Yagi, T.

    2003-12-01

    During the past few years, a novel set of methods has been developed allowing direct measurements on elasticity and rheology under static ultrahigh pressures using synchrotron x-ray diffraction and the diamond anvil cell. In particular, the analysis on the development of texture and uniaxial stress in a polycrystalline sample under ultrahigh pressure and non-hydrostatic conditions yielded to very interesting results on the microscopic deformation mechanisms and strength of MgO, silicate perovskite or ɛ -Fe [eg. Merkel et al. 2002, Merkel et al. 2003]. However, our understanding of the properties of the ɛ phase of iron remains poor. There are considerable uncertainties and disagreement on the results of various experiments or first-principles calculations. In particular, the results of the radial diffraction measurement on ɛ -Fe [Mao et al. 1998] have been highly controversial. In order to address this issue, we performed investigations on polycrystalline hcp-cobalt. Its properties such as the bulk modulus and thermal expansion are very close to those of ɛ -Fe and it is readily available under ambient conditions. Thus, it is a well known material and results from the high pressure radial diffraction experiments can be compared with those from well-established techniques. In the present analysis, we performed a new set a measurements between 0 and 20 GPa under ambient temperature conditions at the ESRF synchrotron source using amorphous boron gasket, monochromatic x-ray beam, and imaging plate techniques. From such an experiment, we are able to extract information on non-hydrostatic stress, elasticity, and preferred orientations of the sample in-situ under high pressure and compare them with results obtained previously on ɛ -Fe. Documenting the evolution of stress, elasticity and texture in hcp metals is of great interest for our understanding of the bulk properties and seismic anisotropy of the Earth's inner core. S. Merkel et al., J. Geophys. Res. 107 (2002

  18. MHD Modeling of Conductors at Ultra-High Current Density

    International Nuclear Information System (INIS)

    Rosenthal, S.E.; Asay, J.R.; Desjarlais, M.P.; Douglas, M.R.; Frese, M.H.; Hall, C.A.; Morse, R.L.; Reisman, D.; Spielman, R.B.; Stygar, W.A.

    1999-01-01

    In conjunction with ongoing high-current experiments on Sandia National Laboratories' Z accelerator we have revisited a problem first described in detail by Heinz Knoepfel. MITLs of previous pulsed power accelerators have been in the 1-Tesla regime. Z's disc transmission line (downstream of the current addition) is in a 100-1200 Tesla regime, so its conductors cannot be modeled simply as static infinite conductivity boundaries. Using the MHD code MACH2 we have been investigating conductor hydrodynamics, characterizing the joule heating, magnetic field diffusion, and material deformation, pressure, and velocity over a range of current densities, current rise-times, and conductor materials. Three purposes of this work are ( 1) to quantify power flow losses owing to ultra-high magnetic fields, (2) to model the response of VISAR diagnostic samples in various configurations on Z, and (3) to incorporate the most appropriate equation of state and conductivity models into our MHD computations. Certain features are strongly dependent on the details of the conductivity model. Comparison with measurements on Z will be discussed

  19. Vacuum vessel for thermonuclear device

    International Nuclear Information System (INIS)

    Kikuchi, Mitsuru; Nagashima, Keisuke; Suzuki, Masaru; Onozuka, Masaki.

    1997-01-01

    A vacuum vessel main body and structural members at the inside and the outside of the vacuum vessel main body are constituted by structural materials activated by irradiation of neutrons from plasmas such as stainless steels. Shielding members comprising tungsten or molybdenum are disposed on the surface of the vacuum vessel main body and the structural members of the inside and the outside of the main body. The shielding members have a function also as first walls or a seat member for the first walls. Armor tiles may be disposed to the shielding members. The shielding members and the armor tiles are secured to a securing seat member disposed, for example, to an inner plate of the vacuum vessel main body by bolts. Since the shielding members are disposed, it is not necessary to constitute the vacuum vessel main body and the structural members at the inside and the outside thereof by using a low activation material which is less activated, such as a titanium alloy. (I.N.)

  20. Vacuum vessel for thermonuclear device

    Energy Technology Data Exchange (ETDEWEB)

    Kikuchi, Mitsuru; Nagashima, Keisuke [Japan Atomic Energy Research Inst., Tokyo (Japan); Suzuki, Masaru; Onozuka, Masaki

    1997-07-11

    A vacuum vessel main body and structural members at the inside and the outside of the vacuum vessel main body are constituted by structural materials activated by irradiation of neutrons from plasmas such as stainless steels. Shielding members comprising tungsten or molybdenum are disposed on the surface of the vacuum vessel main body and the structural members of the inside and the outside of the main body. The shielding members have a function also as first walls or a seat member for the first walls. Armor tiles may be disposed to the shielding members. The shielding members and the armor tiles are secured to a securing seat member disposed, for example, to an inner plate of the vacuum vessel main body by bolts. Since the shielding members are disposed, it is not necessary to constitute the vacuum vessel main body and the structural members at the inside and the outside thereof by using a low activation material which is less activated, such as a titanium alloy. (I.N.)

  1. Pion Susceptibilities of the Vacuum in a Modified Global Colour Symmetry Model

    Institute of Scientific and Technical Information of China (English)

    ZONG Hong-Shi; WU Xiao-Hua; DING Xiao-Ping; L0 Xiao-Fu; ZHAO En-Guang

    2001-01-01

    Based on a modified version of the global color symmetry model, the pion susceptibilities of vacuum needed in the QCD sum rule external-field method for the coupling of pseudoscalar current to hadron have bean calculated beyond the vacuum saturation approximation. Comparison with the previous estimations has been given.

  2. Carbon nanotubes based vacuum gauge

    Science.gov (United States)

    Rudyk, N. N.; Il'in, O. I.; Il'ina, M. V.; Fedotov, A. A.; Klimin, V. S.; Ageev, O. A.

    2017-11-01

    We have created an ionization type Vacuum gauge with sensor element based on an array of vertically aligned carbon nanotubes. Obtained asymmetrical current-voltage characteristics at different voltage polarity on the electrode with the CNTs. It was found that when applying a negative potential on an electrode with the CNTs, the current in the gap is higher than at a positive potential. In the pressure range of 1 ÷ 103 Torr vacuum gauge sensitivity was 6 mV/Torr (at a current of 4.5·10-5 A) and in the range of 10-5 ÷ 1 Torr was 10 mV/Torr (at a current of 1.3·10-5 A). It is shown that the energy efficiency of vacuum gauge can be increased in the case where electrode with CNT operates as an emitter of electrons.

  3. Magnetically enhanced vacuum arc thruster

    International Nuclear Information System (INIS)

    Keidar, Michael; Schein, Jochen; Wilson, Kristi; Gerhan, Andrew; Au, Michael; Tang, Benjamin; Idzkowski, Luke; Krishnan, Mahadevan; Beilis, Isak I

    2005-01-01

    A hydrodynamic model of the vacuum arc thruster and its plume is described. Primarily an effect of the magnetic field on the plume expansion and plasma generation is considered. Two particular examples are investigated, namely the magnetically enhanced co-axial vacuum arc thruster (MVAT) and the vacuum arc thruster with ring electrodes (RVAT). It is found that the magnetic field significantly decreases the plasma plume radial expansion under typical conditions. Predicted plasma density profiles in the plume of the MVAT are compared with experimental profiles, and generally a good agreement is found. In the case of the RVAT the influence of the magnetic field leads to plasma jet deceleration, which explains the non-monotonic dependence of the ion current density, on an axial magnetic field observed experimentally

  4. Magnetically enhanced vacuum arc thruster

    Energy Technology Data Exchange (ETDEWEB)

    Keidar, Michael [University of Michigan, Ann Arbor 48109 MI (United States); Schein, Jochen [Alameda Applied Science Corporation, San Leandro, CA 94577 (United States); Wilson, Kristi [Alameda Applied Science Corporation, San Leandro, CA 94577 (United States); Gerhan, Andrew [Alameda Applied Science Corporation, San Leandro, CA 94577 (United States); Au, Michael [Alameda Applied Science Corporation, San Leandro, CA 94577 (United States); Tang, Benjamin [Alameda Applied Science Corporation, San Leandro, CA 94577 (United States); Idzkowski, Luke [Alameda Applied Science Corporation, San Leandro, CA 94577 (United States); Krishnan, Mahadevan [Alameda Applied Science Corporation, San Leandro, CA 94577 (United States); Beilis, Isak I [Tel Aviv University, Tel Aviv (Israel)

    2005-11-01

    A hydrodynamic model of the vacuum arc thruster and its plume is described. Primarily an effect of the magnetic field on the plume expansion and plasma generation is considered. Two particular examples are investigated, namely the magnetically enhanced co-axial vacuum arc thruster (MVAT) and the vacuum arc thruster with ring electrodes (RVAT). It is found that the magnetic field significantly decreases the plasma plume radial expansion under typical conditions. Predicted plasma density profiles in the plume of the MVAT are compared with experimental profiles, and generally a good agreement is found. In the case of the RVAT the influence of the magnetic field leads to plasma jet deceleration, which explains the non-monotonic dependence of the ion current density, on an axial magnetic field observed experimentally.

  5. Quantum electrodynamics with unstable vacuum

    Energy Technology Data Exchange (ETDEWEB)

    Fradkin, E.S. (P.N. Lebedev Physical Inst., USSR Academy of Sciences, Moscow (USSR)); Gitman, D.M. (Moscow Inst. of Radio Engineering Electronics and Automation (USSR)); Shvartsman, Sh.M. (Tomsk State Pedagogical Inst. (USSR))

    1991-01-01

    Intense external fields destabilize vacuum inducing the creation of particle pairs. In this book the formalism of quantum electrodynamics (QED), using a special perturbation theory with matrix propagators, is systematically analyzed for such systems. The developed approach is, however, general for any quantum field with unstable vacuum. The authors propose solutions for real pair-creating fields. They discuss the general form for the causal function and many other Green's functions, as well as methods for finding them. Analogies to the optical theorem and rules for computing total probabilities are given, as are solutions for non-Abelian theories. (orig.).

  6. QED vacuum loops and inflation

    Energy Technology Data Exchange (ETDEWEB)

    Fried, H.M. [Brown University, Department of Physics, Providence, RI (United States); Gabellini, Y. [UMR 6618 CNRS, Institut Non Lineaire de Nice, Valbonne (France)

    2015-03-01

    A QED-based model of a new version of vacuum energy has recently been suggested, which leads to a simple, finite, one parameter representation of dark energy. An elementary, obvious, but perhaps radical generalization is then able to describe both dark energy and inflation in the same framework of vacuum energy. One further, obvious generalization then leads to a relation between inflation and the big bang, to the automatic inclusion of dark matter, and to a possible understanding of the birth (and death) of a universe. (orig.)

  7. QED vacuum loops and inflation

    International Nuclear Information System (INIS)

    Fried, H.M.; Gabellini, Y.

    2015-01-01

    A QED-based model of a new version of vacuum energy has recently been suggested, which leads to a simple, finite, one parameter representation of dark energy. An elementary, obvious, but perhaps radical generalization is then able to describe both dark energy and inflation in the same framework of vacuum energy. One further, obvious generalization then leads to a relation between inflation and the big bang, to the automatic inclusion of dark matter, and to a possible understanding of the birth (and death) of a universe. (orig.)

  8. Time response of protection in event of vacuum failure based on Nude ionization gauge controller

    Science.gov (United States)

    Gao, Hui; Wang, Qiuping; Wang, Weibin; Wu, Qinglin; Chen, Wentong; Sheng, Liusi; Zhang, Yunwu

    2001-10-01

    This article describes the design and application of fast-response vacuum protection sensor module, based on the Nude ionization gauge and a homemade controller named GH07X. A simulative test indicated that the controller's response time was less than 200 μs when 1 atm air rushed into the vacuum system through a pulsed valve with 0.8 mm orifice nozzle and the emitting current of the Nude gauge was 4 mA. The experiment result showed that the response time mainly depended on the gas density as well as the electron emitting current of the Nude gauge filament. Compared with the vacuum protection sensors based on sputter ion pump and cold-cathode gauge, GH07X is faster and reliable besides, GH07X can be used as an ultrahigh-vacuum slow valve interlock controller with response time of 100 ms, which is faster than other gauge controllers. The widely used field-bus interface CAN and common serial interface RS232/RS485 are embedded in GH07X controller system.

  9. Proceedings of the Japan-U.S. workshop P-118 on vacuum technologies for fusion devices

    International Nuclear Information System (INIS)

    Miyahara, A.

    1989-01-01

    Fusion community does not appreciate vacuum technologies to the same extent as accelerator community does. This is because, in the case of accelerators, in particular storage ring systems, the requirement of attaining ultrahigh vacuum in order to avoid collisional loss is well defined, on the other hand, it is not possible to define the requirement so precisely in the case of fusion devices. One of the reasons is that core plasma interacts with vessel wall so strongly and unpredictably that it becomes difficult to identify the role played by individual components. However, in the next step and the next generation machines like CIT, LHS, ITER, FER and NET, vacuum technologies would play more significant roles, because the CIT will introduce tritium in a vacuum vessel, and the aim of the ITER project is to demonstrate particle balance, namely, to achieve steady state operation with D-T fuel. The Japan-U.S. workshop P-118 was held at the Institute of Plasma Physics, Nagoya University, from August 1 to 5, 1988. 33 participants including 4 from the U.S. took part in the workshop. In the plenary session, 12 lectures were given, and also the topics-oriented session on pumping, gauging, remote maintenance, first wall, pump limiter, divertor and others was held. (K.I.)

  10. A scheme of measurement of quantum-vacuum geometric phases in a noncoplanar fibre system

    International Nuclear Information System (INIS)

    Shen Jianqi

    2004-01-01

    We study the quantum-vacuum geometric phases resulting from the vacuum fluctuation of photon fields in a Tomita-Chiao-Wu noncoplanar curved fibre system, and suggest a scheme to test for the potential existence of such a vacuum effect. Since the signs of the quantum-vacuum geometric phases of left- and right-handed (LRH) circularly polarized light are opposite, the sum of the geometric phases at the vacuum level is necessarily zero in the fibre experiments performed previously by other authors. By using the present approach where a fibre made of gyroelectric media is employed, the quantum-vacuum geometric phases of LRH light cannot be exactly cancelled, and it may therefore be possible to test this experimentally. (letter to the editor)

  11. Previously unknown species of Aspergillus.

    Science.gov (United States)

    Gautier, M; Normand, A-C; Ranque, S

    2016-08-01

    The use of multi-locus DNA sequence analysis has led to the description of previously unknown 'cryptic' Aspergillus species, whereas classical morphology-based identification of Aspergillus remains limited to the section or species-complex level. The current literature highlights two main features concerning these 'cryptic' Aspergillus species. First, the prevalence of such species in clinical samples is relatively high compared with emergent filamentous fungal taxa such as Mucorales, Scedosporium or Fusarium. Second, it is clearly important to identify these species in the clinical laboratory because of the high frequency of antifungal drug-resistant isolates of such Aspergillus species. Matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) has recently been shown to enable the identification of filamentous fungi with an accuracy similar to that of DNA sequence-based methods. As MALDI-TOF MS is well suited to the routine clinical laboratory workflow, it facilitates the identification of these 'cryptic' Aspergillus species at the routine mycology bench. The rapid establishment of enhanced filamentous fungi identification facilities will lead to a better understanding of the epidemiology and clinical importance of these emerging Aspergillus species. Based on routine MALDI-TOF MS-based identification results, we provide original insights into the key interpretation issues of a positive Aspergillus culture from a clinical sample. Which ubiquitous species that are frequently isolated from air samples are rarely involved in human invasive disease? Can both the species and the type of biological sample indicate Aspergillus carriage, colonization or infection in a patient? Highly accurate routine filamentous fungi identification is central to enhance the understanding of these previously unknown Aspergillus species, with a vital impact on further improved patient care. Copyright © 2016 European Society of Clinical Microbiology and

  12. Gases and vacua handbook of vacuum physics

    CERN Document Server

    Beck, A H

    2013-01-01

    Handbook of Vacuum Physics, Volume 1: Gases and Vacua provides information on the many aspects of vacuum technology, from material on the quantum theoretical aspects of the complex semi-conductors used for thermionic and photo-electric emission to data on the performance of commercially available pumps, gauges, and high-vacuum materials. The handbook satisfies the need of workers using vacuum apparatuses or works on the diverse applications of high-vacuum technology in research and industry. The book is a compilation of long articles prepared by experts in vacuum technology. Sufficient theoret

  13. The Source of the Quantum Vacuum

    Directory of Open Access Journals (Sweden)

    Daywitt W. C.

    2009-01-01

    Full Text Available The quantum vacuum consists of virtual particles randomly appearing and disappearing in free space. Ordinarily the wavenumber (or frequency spectrum of the zero-point fields for these virtual particles is assumed to be unbounded. The unbounded nature of the spectrum leads in turn to an infinite energy density for the quantum vacuum and an infinite renormalization mass for the free particle. This paper argues that there is a more fundamental vacuum state, the Planck vacuum, from which the quantum vacuum emerges and that the “graininess” of this more fundamental vacuum state truncates the wavenumber spectrum and leads to a finite energy density and a finite renormalization mass.

  14. The Source of the Quantum Vacuum

    Directory of Open Access Journals (Sweden)

    Daywitt W. C.

    2009-01-01

    Full Text Available The quantum vacuum consists of virtual particles randomly appearing and disappearing in free space. Ordinarily the wavenumber (or frequency spectrum of the zero-point fields for these virtual particles is assumed to be unbounded. The unbounded nature of the spectrum leads in turn to an infinite energy density for the quantum vacuum and an infinite renormalization mass for the free particle. This paper argues that there is a more fundamental vacuum state, the Planck vacuum, from which the quantum vacuum emerges and that the "graininess" of this more fundamental vacuum state truncates the wavenumber spectrum and leads to a finite energy density and a finite renormalization mass.

  15. Vacuum-insulated catalytic converter

    Science.gov (United States)

    Benson, David K.

    2001-01-01

    A catalytic converter has an inner canister that contains catalyst-coated substrates and an outer canister that encloses an annular, variable vacuum insulation chamber surrounding the inner canister. An annular tank containing phase-change material for heat storage and release is positioned in the variable vacuum insulation chamber a distance spaced part from the inner canister. A reversible hydrogen getter in the variable vacuum insulation chamber, preferably on a surface of the heat storage tank, releases hydrogen into the variable vacuum insulation chamber to conduct heat when the phase-change material is hot and absorbs the hydrogen to limit heat transfer to radiation when the phase-change material is cool. A porous zeolite trap in the inner canister absorbs and retains hydrocarbons from the exhaust gases when the catalyst-coated substrates and zeolite trap are cold and releases the hydrocarbons for reaction on the catalyst-coated substrate when the zeolite trap and catalyst-coated substrate get hot.

  16. Investigations of Pulsed Vacuum Gap.

    Science.gov (United States)

    1981-02-10

    Violet Spectra of Hot Sparks in Hh’Iacua, ’ ?hys. Rev., Vol. 12, p. 167, (1913). 31A Maitland , "Spark CondiiIoning Equation for Olane ElectrodesI-in...Appl. Phys., Vol. 1, 1291 G. Thecohilus, K. Srivastava, and R. ’ ian Heeswi.k, ’tn-situ Observation of !Microparticles in a Vacuum-Tnsulated Gap Using

  17. PC driven integrated vacuum system

    International Nuclear Information System (INIS)

    Curuia, M.; Culcer, M.; Brandea, I.; Anghel, M.

    2001-01-01

    The paper presents a integrated vacuum system which was designed and manufactured in our institute. The main parts of this system are the power supply unit for turbo-melecular pumps and the vacuummeter. Both parts of the system are driven by means of a personal computer using a serial communication, according to the RS 232 hardware standard.(author)

  18. Vacuum therapy for chronic wounds

    Directory of Open Access Journals (Sweden)

    Ekaterina Leonidovna Zaytseva

    2012-09-01

    Full Text Available Chronic wound in patients with diabetes mellitus (DM is one of the most urgent problems of modern diabetology and surgery. Numberof patients suffering from different types of chronic wounds follows increase in DM incidence. Vacuum therapy is a novel perspectivemethod of topical treatment for non-healing chronic wounds of various etiology. Current review addresses experimental and clinicalevidence for this method.

  19. Filling the vacuum at LHCb

    CERN Multimedia

    Katarina Anthony

    2013-01-01

    Last month, the Vacuum, Surfaces and Coatings (VSC) group was tasked with an unusually delicate operation in the LHCb experiment cavern: removing the LHC beam pipe while keeping the sensitive Vertex Locator vacuum vessel (VELO) completely isolated from the action.   The VSC group seal off the VELO beam pipe with a flange. Image: Gloria Corti. LHCb’s VELO detector is one of the crown jewels of the experiment. With detector elements surrounded by a vacuum, it gets as close as 5 cm from the beam. Fantastic for physics, but difficult for all-important access. “Because of the sensitivity of the VELO detector and its proximity to the beam, the collaboration decided not to bake (see box) its portion of the beam pipe,” says Giulia Lanza (TE-VSC-LBV), the expert in charge of the beam vacuum operation. “Our group was therefore asked to remove the rest of the LHC beam pipe while keeping the VELO portion of the pipe completely isolated. This work...

  20. HIGH PRODUCTIVITY VACUUM BLASTING SYSTEM

    International Nuclear Information System (INIS)

    McPhee, William S.

    1999-01-01

    The objective of this project is to improve the productivity and lower the expense of existing vacuum blasting technology. This technology is used to remove radioactive contamination, PCBs, and lead-based paint and provides worker protection by continuously recycling the material and dust for the decontamination tasks. The proposed work would increase the cleaning rate and provide safe and cost-effective decontamination of the DOE sites. This work focuses on redesigning and improving existing vacuum blasting technology including blast head nozzles, ergonomic handling of the blast head by reducing its weight; brush-ring design, vacuum level regulator, efficiency of the dust separator, and operational control sensors. The redesign is expected to enhance the productivity and economy of the vacuum blasting system by at least 50% over current vacuum blasting systems. There are three phases in the project. Phase I consists of developing and testing mathematical models. Phase II consists of pre-prototype design and fabrication and pre-prototype unit testing. Phase III consists of prototype design and field verification testing. In phase I, mathematical models are developed and analyzed for the nozzle, blast head, wind curtain, and dust separator, first as individual devices and then combined as an integrated model. This allows study of respective airflow and design parameters. The Contractor shall, based on the results of the mathematical modeling studies, design experimental models of the components and test these models. In addition, the Contractor shall develop sensors to detect the relationship of the blast head to the blast surfaces and controls to minimize the dependency on an operator's skill and judgment to obtain optimum positioning, as well as real-time characterization sensors to determine as the blast head is moving the depth to which coatings must be removed, thereby improving production and minimizing waste. In phase II, the Contractor shall design and

  1. Ultra-high resolution protein crystallography

    International Nuclear Information System (INIS)

    Takeda, Kazuki; Hirano, Yu; Miki, Kunio

    2010-01-01

    Many protein structures have been determined by X-ray crystallography and deposited with the Protein Data Bank. However, these structures at usual resolution (1.5< d<3.0 A) are insufficient in their precision and quantity for elucidating the molecular mechanism of protein functions directly from structural information. Several studies at ultra-high resolution (d<0.8 A) have been performed with synchrotron radiation in the last decade. The highest resolution of the protein crystals was achieved at 0.54 A resolution for a small protein, crambin. In such high resolution crystals, almost all of hydrogen atoms of proteins and some hydrogen atoms of bound water molecules are experimentally observed. In addition, outer-shell electrons of proteins can be analyzed by the multipole refinement procedure. However, the influence of X-rays should be precisely estimated in order to derive meaningful information from the crystallographic results. In this review, we summarize refinement procedures, current status and perspectives for ultra high resolution protein crystallography. (author)

  2. Measurement system for ultrahigh temperature thermophysical properties

    International Nuclear Information System (INIS)

    Fukuyama, Hiroyuki

    2015-01-01

    Properties and Simulations Probed with Electromagnetic Containerless Technique (PROSPECT) is a measurement system for ultrahigh temperature thermophysical properties to be able to measure thermophysical properties with high precision by combining AC magnetic field (electromagnetic levitation device) and DC magnetic field (superconducting magnet) to realize the static floating state of metallic melt, in other words, the state of suppressing the surface vibration of droplets, translational motion, and internal convection. The electromagnetic levitation method is a method to obtain a floating force due to the Lorentz force generated by the interaction between high-frequency current flowing in the coil and the induced current generated in a sample, and to heat/melt the sample with the Joule heat generated by its induced current. This paper roughly explains the element technologies of PROSPECT with a focus on the laser modulation calorimetry (laser periodic heating method), normal spectral emissivity measurement method, density measurement, and surface tension measurement method. Furthermore, as the application of PROSPECT to new research deployment, it introduces the observation of phase separation structure in the supercooled solidification structure of Cu-Co alloy. (A.O.)

  3. Ultrahigh Ductility, High-Carbon Martensitic Steel

    Science.gov (United States)

    Qin, Shengwei; Liu, Yu; Hao, Qingguo; Zuo, Xunwei; Rong, Yonghua; Chen, Nailu

    2016-10-01

    Based on the proposed design idea of the anti-transformation-induced plasticity effect, both the additions of the Nb element and pretreatment of the normalization process as a novel quenching-partitioning-tempering (Q-P-T) were designed for Fe-0.63C-1.52Mn-1.49Si-0.62Cr-0.036Nb hot-rolled steel. This high-carbon Q-P-T martensitic steel exhibits a tensile strength of 1890 MPa and elongation of 29 pct accompanied by the excellent product of tensile and elongation of 55 GPa pct. The origin of ultrahigh ductility for high-carbon Q-P-T martensitic steel is revealed from two aspects: one is the softening of martensitic matrix due to both the depletion of carbon in the matensitic matrix during the Q-P-T process by partitioning of carbon from supersaturated martensite to retained austenite and the reduction of the dislocation density in a martensitic matrix by dislocation absorption by retained austenite effect during deformation, which significantly enhances the deformation ability of martensitic matrix; another is the high mechanical stability of considerable carbon-enriched retained austenite, which effectively reduces the formation of brittle twin-type martensite. This work verifies the correctness of the design idea of the anti-TRIP effect and makes the third-generation advanced high-strength steels extend to the field of high-carbon steels from low- and medium-carbon steels.

  4. Ultrahigh iodine adsorption in porous organic frameworks

    KAUST Repository

    Pei, Cuiying

    2014-01-01

    We present two porous organic frameworks (POFs), PAF-1 and JUC-Z2, with ultrahigh iodine capture capacity. The iodine vapor uptake of PAF-1 and JUC-Z2 were 1.86 g g-1 and 1.44 g g-1 respectively at 298 K per 40 Pa, which is extremely high for such low pressure sorption conditions. In addition, PAF-1 and JUC-Z2 could adsorb iodine over water with the selectivity of 5.1 and 6.5 respectively. The isosteric enthalpy at zero surface coverage, calculated by a virial equation with the iodine vapor sorption isotherms at 298 K and 313 K of JUC-Z2, reached -51.1 kJ mol-1, which was much higher than the coverage of PAF-1 (-14.9 kJ mol-1). Raman measurement confirmed the polyiodide to be I5 - in POFs. Furthermore, solvents with different polarities, such as n-hexane, chloroform, and methanol, were chosen to conduct iodine binding measurements on PAF-1 and JUC-Z2. The formation constant Kf for POFs in n-hexane, chloroform and methanol drastically decreased with the increase in polarity, thus illustrating the important role of solvents in iodine binding. © the Partner Organisations 2014.

  5. Vacuum surface flashover and high pressure gas streamers

    International Nuclear Information System (INIS)

    Elizondo, J.M.; Krogh, M.L.; Smith, D.; Stolz, D.; Wright, S.N.

    1997-07-01

    Pre-breakdown current traces obtained during high pressure gas breakdown and vacuum surface flashover show similar signatures. The initial pre-breakdown current spike, a flat constant current phase, and the breakdown phase with voltage collapse and current surge differ mostly in magnitude. Given these similarities, a model, consisting of the initial current spike corresponding to a fast precursor streamer (ionization wave led by a photoionizing front), the flat current stage as the heating or glow phase, and the terminal avalanche and gap closure, is applied to vacuum surface flashover. A simple analytical approximation based on the resistivity changes induced in the vacuum and dielectric surface is presented. The approximation yields an excellent fit to pre-breakdown time delay vs applied field for previously published experimental data. A detailed kinetics model that includes surface and gas contributions is being developed based in the initial approximation

  6. Living beyond the edge: Higgs inflation and vacuum metastability

    CERN Document Server

    Bezrukov, Fedor; Shaposhnikov, Mikhail

    2015-01-01

    The measurements of the Higgs mass and top Yukawa coupling indicate that we live in a very special Universe, at the edge of the absolute stability of the electroweak vacuum. If fully stable, the Standard Model (SM) can be extended all the way up to the inflationary scale and the Higgs field, non-minimally coupled to gravity with strength $\\xi$, can be responsible for inflation. We show that the successful Higgs inflation scenario can also take place if the SM vacuum is not absolutely stable. This conclusion is based on two effects that were overlooked previously. The first one is associated with the effective renormalization of the SM couplings at the energy scale $M_P/\\xi$, where $M_P$ is the Planck scale. The second one is a symmetry restoration after inflation due to high temperature effects that leads to the (temporary) disappearance of the vacuum at Planck values of the Higgs field.

  7. Conditioning of the vacuum chamber of the Tokamak Novillo

    International Nuclear Information System (INIS)

    Valencia A, R.; Lopez C, R.; Melendez L, L.; Chavez A, E.; Colunga S, S.; Gaytan G, E.

    1992-03-01

    The obtained experimental results of the implementation of two techniques of present time for the conditioning of the internal wall of the chamber of discharges of the Tokamak Novillo are presented, which has been designed, built and put in operation in the Laboratory of Plasma Physics of the National Institute of Nuclear Research (ININ). These techniques are: the vacuum baking and the low energy pulsed discharges, which were applied after having reached an initial pressure of the order of 10 -7 Torr. with a system of turbomolecular pumping previous preparation of surfaces and vacuum seals. The analysis of residual gases was carried out with a mass spectrometer before and after conditioning. The obtained results show that the vacuum baking it was of great effectiveness to reduce the value of the initial pressure in short time, in more of a magnitude order and the low energy discharges reduced the oxygen at worthless levels with regard to the initial values. (Author)

  8. Regulating vacuum pump speed with feedback control

    International Nuclear Information System (INIS)

    Ludington, D.C.; Aneshansley, D.J.; Pellerin, R.; Guo, F.

    1992-01-01

    Considerable energy is wasted by the vacuum pump/motor on dairy farms. The output capacity (m 3 /min or cfm) of the vacuum pump always exceeds the capacity needed to milk cows and wash pipelines. Vacuum pumps run at full speed and load regardless of actual need for air. Excess air is admitted through a controller. Energy can be saved from electrical demand reduced by regulating vacuum pump speed according to air based on air usage. An adjustable speed drive (ASD) on the motor and controlled based upon air usage, can reduce the energy used by the vacuum pump. However, the ASD unit tested could not maintain vacuum levels within generally accepted guidelines when air usage changed. Adding a high vacuum reserve and a dual vacuum controller between the vacuum pump and the milking pipeline brought vacuum stability within guidelines. The ASD/dual vacuum system can reduce energy consumption and demand by at least 50 percent during milking and provide better vacuum stability than conventional systems. Tests were not run during washing cycles. Using 1990 costs and only the energy saved during milking, the simple payback on investment in new equipment for a 5 hp motor, speed controller and vacuum regulator would be about 5 years

  9. Vacuum polarization and Hawking radiation

    Science.gov (United States)

    Rahmati, Shohreh

    Quantum gravity is one of the interesting fields in contemporary physics which is still in progress. The purpose of quantum gravity is to present a quantum description for spacetime at 10-33cm or find the 'quanta' of gravitational interaction.. At present, the most viable theory to describe gravitational interaction is general relativity which is a classical theory. Semi-classical quantum gravity or quantum field theory in curved spacetime is an approximation to a full quantum theory of gravity. This approximation considers gravity as a classical field and matter fields are quantized. One interesting phenomena in semi-classical quantum gravity is Hawking radiation. Hawking radiation was derived by Stephen Hawking as a thermal emission of particles from the black hole horizon. In this thesis we obtain the spectrum of Hawking radiation using a new method. Vacuum is defined as the possible lowest energy state which is filled with pairs of virtual particle-antiparticle. Vacuum polarization is a consequence of pair creation in the presence of an external field such as an electromagnetic or gravitational field. Vacuum polarization in the vicinity of a black hole horizon can be interpreted as the cause of the emission from black holes known as Hawking radiation. In this thesis we try to obtain the Hawking spectrum using this approach. We re-examine vacuum polarization of a scalar field in a quasi-local volume that includes the horizon. We study the interaction of a scalar field with the background gravitational field of the black hole in the desired quasi-local region. The quasi-local volume is a hollow cylinder enclosed by two membranes, one inside the horizon and one outside the horizon. The net rate of particle emission can be obtained as the difference of the vacuum polarization from the outer boundary and inner boundary of the cylinder. Thus we found a new method to derive Hawking emission which is unitary and well defined in quantum field theory.

  10. Compactified vacuum in ten dimensions

    International Nuclear Information System (INIS)

    Wurmser, D.

    1987-01-01

    Since the 1920's, theories which unify gravity with the other fundamental forces have called for more than the four observed dimensions of space-time. According to such a theory, the vacuum consists of flat four-dimensional space-time described by the Minkowski metric M 4 and a compactified space B. The dimensions of B are small, and the space can only be observed at distance scales smaller than the present experimental limit. These theories have had serious difficulties. The equations of gravity severely restrict the possible choices for the space B. The allowed spaces are complicated and difficult to study. The vacuum is furthermore unstable in the sense that a small perturbation causes the compactified dimensions to expand indefinitely. There is an addition a semi-classical argument which implies that the compactified vacuum by annihilated by virtual black holes. It follows that a universe with compactified extra dimensions could not have survived to the present. These results were derived by applying the equations of general relativity to spaces of more than four dimensions. The form of these equations was assumed to be unchanged by an increase in the number of dimensions. The authors illustrate the effect of such terms by considering the example B = S 6 where S 6 is the six-dimensional sphere. Only when the extra terms are included is this choice of the compactified space allowed. He explore the effect of a small perturbation on such a vacuum. The ten-dimensional spherically symmetric potential is examined, and I determine conditions under which the formation of virtual black holes is forbidden. The examples M 4 x S 6 is still plagued by the semi-classical instability, but this result does not hold in general. The requirement that virtual black holes be forbidden provides a test for any theory which predicts a compactified vacuum

  11. Effect of vacuum energy on evolution of primordial black holes in Einstein gravity

    International Nuclear Information System (INIS)

    Nayak, Bibekananda; Jamil, Mubasher

    2012-01-01

    We study the evolution of primordial black holes by considering present universe is no more matter dominated rather vacuum energy dominated. We also consider the accretion of radiation, matter and vacuum energy during respective dominance period. In this scenario, we found that radiation accretion efficiency should be less than 0.366 and accretion rate is much larger than previous analysis by Nayak et al. (2009) . Thus here primordial black holes live longer than previous works Nayak and Singh (2011). Again matter accretion slightly increases the mass and lifetime of primordial black holes. However, the vacuum energy accretion is slightly complicated one, where accretion is possible only up to a critical time. If a primordial black hole lives beyond critical time, then its' lifespan increases due to vacuum energy accretion. But for presently evaporating primordial black holes, critical time comes much later than their evaporating time and thus vacuum energy could not affect those primordial black holes.

  12. Review of Current Nuclear Vacuum System Technologies

    International Nuclear Information System (INIS)

    Carroll, M.; McCracken, J.; Shope, T.

    2003-01-01

    Nearly all industrial operations generate unwanted dust, particulate matter, and/or liquid wastes. Waste dust and particulates can be readily tracked to other work locations, and airborne particulates can be spread through ventilation systems to all locations within a building, and even vented outside the building - a serious concern for processes involving hazardous, radioactive, or nuclear materials. Several varieties of vacuum systems have been proposed and/or are commercially available for clean up of both solid and liquid hazardous and nuclear materials. A review of current technologies highlights both the advantages and disadvantages of the various systems, and demonstrates the need for a system designed to address issues specific to hazardous and nuclear material cleanup. A review of previous and current hazardous/nuclear material cleanup technologies is presented. From simple conventional vacuums modified for use in industrial operations, to systems specifically engineered for such purposes, the advantages and disadvantages are examined in light of the following criteria: minimal worker exposure; minimal secondary waste generation;reduced equipment maintenance and consumable parts; simplicity of design, yet fully compatible with all waste types; and ease of use. The work effort reviews past, existing and proposed technologies in light of such considerations. Accomplishments of selected systems are presented, including identified areas where technological improvements could be suggested

  13. Gauge field vacuum structure in geometrical aspect

    International Nuclear Information System (INIS)

    Konopleva, N.P.

    2003-01-01

    Vacuum conception is one of the main conceptions of quantum field theory. Its meaning in classical field theory is also very profound. In this case the vacuum conception is closely connected with ideas of the space-time geometry. The global and local geometrical space-time conceptions lead to different vacuum definitions and therefore to different ways of physical theory construction. Some aspects of the gauge field vacuum structure are analyzed. It is shown that in the gauge field theory the vacuum Einstein equation solutions describe the relativistic vacuum as common vacuum of all gauge fields and its sources. Instantons (both usual and hyperbolical) are regarded as nongravitating matter, because they have zero energy-momentum tensors and correspond to vacuum Einstein equations

  14. Characteristics of the ISABELLE vacuum system

    International Nuclear Information System (INIS)

    Aggus, J.R.; Edwards, D. Jr.; Halama, H.J.; Herrera, J.C.

    1977-01-01

    A discussion is given of the complete vacuum system of ISABELLE, emphasizing those design characteristics dictated by high vacuum, the avoidance of beam current loss, and the reduction of background. The experimental and theoretical justifications for the design are presented

  15. Research on vacuum insulation for cryocables

    International Nuclear Information System (INIS)

    Graneau, P.

    1974-01-01

    Vacuum insulation, as compared with solid insulation, simplifies the construction of both resistive or superconducting cryogenic cables. The common vacuum space in the cable can furnish thermal insulation between the environment and the cryogenic coolant, provide electrical insulation between conductors, and establish thermal isolation between go- and return-coolant streams. The differences between solid and vacuum high voltage insulation are discussed, and research on the design, materials selection, and testing of vacuum insulated cryogenic cables is described

  16. Design and performance of main vacuum pumping system of SST-1 Tokamak

    Energy Technology Data Exchange (ETDEWEB)

    Khan, Ziauddin, E-mail: ziauddin@ipr.res.in; Pathan, Firozkhan; George, Siju; Dhanani, Kalpesh; Paravastu, Yuvakiran; Semwal, Pratibha; Pradhan, Subrata

    2014-01-15

    Highlights: •SST-1 Tokamak was successfully commissioned. •Vacuum vessel and cryostat were pumped down to 6.3 × 10{sup −7} mbar and 1.3 × 10{sup −5} mbar. •Leaks developed during baking were detected in-situ by RGA and confirmed later on. •Cryo-pumping effect was observed when LN2 thermal shields reached below 273 K. •Non-standard aluminum wire-seals have shown leak tightness < 1.0 × 10{sup −9} mbar l/s. -- Abstract: Steady-state Superconducting Tokamak (SST-1) was installed and it is commissioning for overall vacuum integrity, magnet systems functionality in terms of successful cool down to 4.5 K and charging up to 10 kA current was started from August 2012. Plasma operation of 100 kA current for more than 100 ms was also envisaged. It is comprised of vacuum vessel (VV) and cryostat (CST). Vacuum vessel, an ultra-high (UHV) vacuum chamber with net volume of 23 m{sup 3} was maintained at the base pressure of 6.3 × 10{sup −7} mbar for plasma confinement. Cryostat, a high-vacuum (HV) chamber with empty volume 39 m{sup 3} housing superconducting magnet system, bubble thermal shields and hydraulics for these circuits, maintained at 1.3 × 10{sup −5} mbar in order to provide suitable environment for these components. In order to achieve these ultimate vacuums, two numbers of turbo-molecular pumps (TMP) are installed in vacuum vessel while three numbers of turbo-molecular pumps are installed in cryostat. Initial pumping of both the chambers was carried out by using suitable Roots pumps. PXI based real time controlled system is used for remote operation of the complete pumping operation. In order to achieve UHV inside the vacuum vessel, it was baked at 150 °C for longer duration. Aluminum wire-seals were used for all non-circular demountable ports and a leak tightness < 1.0 × 10{sup −9} mbar l/s were achieved.

  17. Beyond sixfold coordinated Si in SiO2 glass at ultrahigh pressures.

    Science.gov (United States)

    Prescher, Clemens; Prakapenka, Vitali B; Stefanski, Johannes; Jahn, Sandro; Skinner, Lawrie B; Wang, Yanbin

    2017-09-19

    We investigated the structure of SiO 2 glass up to 172 GPa using high-energy X-ray diffraction. The combination of a multichannel collimator with diamond anvil cells enabled the measurement of structural changes in silica glass with total X-ray diffraction to previously unachievable pressures. We show that SiO 2 first undergoes a change in Si-O coordination number from fourfold to sixfold between 15 and 50 GPa, in agreement with previous investigations. Above 50 GPa, the estimated coordination number continuously increases from 6 to 6.8 at 172 GPa. Si-O bond length shows first an increase due to the fourfold to sixfold coordination change and then a smaller linear decrease up to 172 GPa. We reconcile the changes in relation to the oxygen-packing fraction, showing that oxygen packing decreases at ultrahigh pressures to accommodate the higher than sixfold Si-O coordination. These results give experimental insight into the structural changes of silicate glasses as analogue materials for silicate melts at ultrahigh pressures.

  18. Color-magnetic permeability of QCD vacuum

    Energy Technology Data Exchange (ETDEWEB)

    Saito, T [Kyoto Prefectural Univ. of Medicine (Japan); Shigemoto, K

    1980-03-01

    In the very strong background gauge field the QCD true vacuum has been shown to have lower energy than the ''perturbative vacuum.'' The color-magnetic permeability of the QCD true vacuum is then calculated to be 1/2 within the quark-one-loop approximation.

  19. 46 CFR 154.804 - Vacuum protection.

    Science.gov (United States)

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Vacuum protection. 154.804 Section 154.804 Shipping... Systems § 154.804 Vacuum protection. (a) Except as allowed under paragraph (b) of this section, each cargo tank must have a vacuum protection system meeting paragraph (a)(1) of this section and either paragraph...

  20. Hadronic vacuum polarization in true muonium

    Science.gov (United States)

    Lamm, Henry

    2017-01-01

    In order to reduce the theoretical uncertainty in the prediction, the leading-order hadronic vacuum polarization contribution to the hyperfine splitting of true muonium is reevaluated in two ways. A more complex pionic form factor and better estimates of the perturbative QCD contributions are used to study the model dependence of the previous calculation. The second, more accurate method directly integrates the Drell ratio R (s ) to obtain C1 ,HVP=-0.04874 (9 ) . This corresponds to an energy shift in the hyperfine splitting (HFS) of Δ EHFS,HVP μ=-8202 (16 ) MHz and represents a factor-of-50 reduction in the theoretical uncertainty from hadronic sources. We also compute the contribution in positronium, which is too small at present to detect.

  1. Cathodic Vacuum Arc Plasma of Thallium

    International Nuclear Information System (INIS)

    Yushkov, Georgy Yu.; Anders, Andre

    2006-01-01

    Thallium arc plasma was investigated in a vacuum arc ion source. As expected from previous consideration of cathode materials in the Periodic Table of the Elements, thallium plasma shows lead-like behavior. Its mean ion charge state exceeds 2.0 immediately after arc triggering, reaches the predicted 1.60 and 1.45 after about 100 microsec and 150 microsec, respectively. The most likely ion velocity is initially8000 m/s and decays to 6500 m/s and 6200 m/s after 100 microsec and 150microsec, respectively. Both ion charge states and ion velocities decay further towards steady state values, which are not reached within the 300microsec pulses used here. It is argued that the exceptionally high vapor pressure and charge exchange reactions are associated with the establishment of steady state ion values

  2. "Flat-Fish" Vacuum Chamber

    CERN Multimedia

    CERN PhotoLab

    1978-01-01

    The picture shows a "Flat-Fish" vacuum chamber being prepared in the ISR workshop for testing prior to installation in the Split Field Magnet (SFM) at intersection I4. The two shells of each part were hydroformed from 0.15 mm thick inconel 718 sheet (with end parts in inconel 600 for easier manual welding to the arms) and welded toghether with two strips which were attached by means of thin stainless steel sheets to the Split Field Magnet poles in order to take the vertical component of the atmospheric pressure force. This was the thinnest vacuum chamber ever made for the ISR. Inconel material was chosen for its high elastic modulus and strenght at chamber bake-out temperature. In this picture the thin sheets transferring the vertical component of the atmosferic pressure force are attached to a support frame for testing. See also 7712182, 7712179.

  3. LEP vacuum chamber, early prototype

    CERN Multimedia

    CERN PhotoLab

    1978-01-01

    The structure of LEP, with long bending magnets and little access to the vacuum chamber between them, required distributed pumping. This is an early prototype for the LEP vacuum chamber, made from extruded aluminium. The main opening is for the beam. The small channel to the right is for cooling water, to carry away the heat deposited by the synchroton radiation from the beam. The 4 slots in the channel to the left house the strip-shaped ion-getter pumps (see 7810255). The ion-getter pumps depended on the magnetic field of the bending magnets, too low at injection energy for the pumps to function well. Also, a different design was required outside the bending magnets. This design was therefore abandoned, in favour of a thermal getter pump (see 8301153 and 8305170).

  4. HIGH PRODUCTIVITY VACUUM BLASTING SYSTEM

    International Nuclear Information System (INIS)

    McPhee, William S.

    2001-01-01

    The Department of Energy (DOE) needs improved technologies to decontaminate large areas of both concrete and steel surfaces. The technology should have high operational efficiency, minimize exposures to workers, and produce low levels of secondary waste. In order to meet the DOE's needs, an applied research and development project for the improvement of a current decontamination technology, Vacuum Blasting, is proposed. The objective of this project is to improve the productivity and lower the expense of the existing vacuum blasting technology which has been widely used in DOE sites for removing radioactive contamination, PCBs, and lead-based paint. The proposed work would increase the productivity rate and provide safe and cost-effective decontamination of the DOE sites

  5. Deflated-Victims of vacuum

    International Nuclear Information System (INIS)

    Sanders, Roy E.

    2007-01-01

    Atmospheric pressure combined with a partial vacuum within chemical plant or refinery tanks can result in some ego-deflating moments. This article will review three catastrophic vessel failures in detail and touch on several other incidents. A 4000-gal acid tank was destroyed by a siphoning action; a well maintained tank truck was destroyed during a routine delivery; and a large, brand new refinery mega-vessel collapsed as the steam within it condensed. Seasoned engineers are aware of the frail nature of tanks and provide safeguards or procedures to limit damages. The purpose of this paper is to ensure this new generation of chemical plant/refinery employees understand the problems of the past and take the necessary precautions to guard against tank damages created by partial vacuum conditions

  6. Mirror Fusion vacuum technology developments

    International Nuclear Information System (INIS)

    Batzer, T.H.; Call, W.R.

    1983-01-01

    Magnetic Mirror Fusion experiments, such as MFTF-B+T (Mirror Fusion Test Facility-B, Tritium Upgrade) and foreseeable follow-on devices, have operational and maintenance requirements that have not yet been fully demonstrated. Among those associated with vacuum technology are the very-high continuous-pumping speeds, 10 7 to 10 8 l/s for D 2 , T 2 and, to a lesser extent, He; the early detection of water leaks from the very-high heat-flux neutral-beam dumps and the detection and location of leaks in the superconducting magnets not protected by guard vacuums. Possible solutions to these problems have been identified and considerable progress has been made toward successfully demonstrating their feasibility

  7. Mirror fusion vacuum technology developments

    International Nuclear Information System (INIS)

    Batzer, T.H.; Call, W.R.

    1983-01-01

    Magnetic Mirror Fusion experiments, such as MFTF-B+T (Mirror Fusion Test Facility-B, Tritium Upgrade) and foreseeable follow-on devices, have operational and maintenance requirements that have not yet been fully demonstrated. Among those associated with vacuum technology are the very-high continuous-pumping speeds, 10 7 to 10 8 l/s for D 2 , T 2 and, to a lesser extent, He; the early detection of water leaks from the very-high heat-flux neutral-beam dumps and the detection and location of leaks in the superconducting magnets not protected by guard vacuums. Possible solutions to these problems have been identified and considerable progress has been made toward successfully demonstrating their feasibility

  8. Stretchers and compressors for ultra-high power laser systems

    Energy Technology Data Exchange (ETDEWEB)

    Yakovlev, I V [Institute of Applied Physics, Russian Academy of Sciences, Nizhnii Novgorod (Russian Federation)

    2014-05-30

    This review is concerned with pulse stretchers and compressors as key components of ultra-high power laser facilities that take advantage of chirped-pulse amplification. The potentialities, characteristics, configurations and methods for the matching and alignment of these devices are examined, with particular attention to the history of the optics of ultra-short, ultra-intense pulses before and after 1985, when the chirped-pulse amplification method was proposed, which drastically changed the view of the feasibility of creating ultra-high power laser sources. The review is intended primarily for young scientists and experts who begin to address the amplification and compression of chirped pulses, experts in laser optics and all who are interested in scientific achievements in the field of ultra-high power laser systems. (review)

  9. Vacuum chamber eddy current correction coil for the AGS Booster

    International Nuclear Information System (INIS)

    Danby, G.; Jackson, J.

    1988-01-01

    The AGS Booster injector will perform a variety of functions. Heavy ion acceleration requires a bakeable, ultra-high vacuum system (VC). Acceleration for intense proton beams requires rapid cycling (B /preceq/ 10T/sec). If straight forward heavy walled VC are used, the field perturbations due to eddy currents are large. The state of the art lattice has highly distributed lumped sextupoles capable of substantially correcting the induced field nonlinearity. Nevertheless, for the very highest space charge-intensity limits, it is desirable to have the capability to remove eddy current fields at the source. Correction coils attached to the outside of the VC cancel its current aberrations over the required good field aperture. These can be passively powered by transformer action, using two turn windings around the magnet yoke. Programmed power supplies can also be used. This inexpensive additional correction option uses a three turn per quadrant coil which follows the local contour of the VC. Transverse movements of several mms of the VC will have no beam optical effect since the large field aberrations and their corrections have the same displaced coordinates. Experimental and computer studies will be presented, as well as mechanical and electrical design of a simple method of construction. 6 figs

  10. SLC polarized beam source ultra-high-vacuum design

    International Nuclear Information System (INIS)

    Lavine, T.L.; Clendenin, J.E.; Garwin, E.L.; Hoyt, E.W.; Hoyt, M.W.; Miller, R.H.; Nuttall, J.A.; Schultz, D.C.; Wright, D.

    1991-05-01

    This paper describes the design of the ultra-high vacuum system for the beam-line from the 160-kV polarized electron gun to the linac injector in the Stanford Linear Collider (SLC). The polarized electron source is a GaAs photocathode, requiring 10 -11 -Torr-range pressure for adequate quantum efficiency and longevity. The photo-cathode is illuminated by 3-nsec-long laser pulses. Photo-cathode maintenance and improvements require occasional substitution of guns with rapid restoration of UHV conditions. Differential pumping is crucial since the pressure in the injector is more than 10 times greater than the photocathode can tolerate, and since electron-stimulated gas desorption from beam loss in excess of 0.1% of the 20-nC pulses may poison the photocathode. Our design for the transport line contains a differential pumping region isolated by a pair of valves. Exchange of guns requires venting only this isolated region which can be restored to UHV rapidly by baking. The differential pumping is performed by non-evaporable getters (NEGs) and an ion pump. 3 refs., 3 figs

  11. Vacuum chamber eddy current correction coil for the AGS booster

    International Nuclear Information System (INIS)

    Danby, G.; Jackson, J.

    1988-01-01

    This paper reports on the AGS Booster injector that performs a variety of functions. Heavy ion acceleration requires a bakeable, ultra-high vacuum system (VC). Acceleration for intense proton beams requires rapid cycling (B ≤10T/sec). If straight forward heavy walled VC are used, the field perturbations due to eddy currents are large. The state of the art lattice has highly distributed lumped sextupoles capable of substantially correcting the induced field nonlinearity. Nevertheless, for the very highest space charge-intensity limits, it is desirable to have the capability to remove eddy current fields at the source. Correction coils attached to the outside of the VC cancel its current aberrations over the required good field aperture. These can be passively powered by transformer action, using two turn windings around the magnet yoke. Programmed power supplies can also be used. This inexpensive additional correction option uses a three turn per quadrant coil which follows the local contour of the VC. Transverse movements of several mms of the VC will have no beam optical effect since the large field aberrations and their corrections have the same displace coordinates. Experimental and computer studies will be presented, as well as mechanical and electrical design of a simple method of construction

  12. Quantum friction across the vacuum

    International Nuclear Information System (INIS)

    Ebelein, C.

    1998-01-01

    Friction is so ubiquitous that it seems to be almost trivially familiar. The rubbing of two solid surfaces is opposed by a resistance and accompanied by the production of heat. Engineers still dream of perfectly smooth surfaces that can be moved against each other without any friction. However, this dream has now been shattered by John Pendry of Imperial College, London, who has published a theory that shows that even two perfectly smooth surfaces can experience an appreciable friction when moved relative to each other (J. Phys.: Condens. Matter 1997 9 10301-10320). Moreover, the two surfaces he considers are not even in contact but separated by a gap a lattice constant or so wide. The explanation of this lies in what Pendry calls the shearing of the vacuum in the gap. In quantum physics the vacuum is not just empty nothingness; it is full of virtually everything. The vacuum abounds with virtual photons. These zero-point fluctuations cannot normally be seen, but they give the vacuum a structure that manifests itself in a variety of effects (for example, the Casimir effect). A more subtle, yet more familiar, manifestation of these zero-point fluctuations is the van der Waals force. The effect described by Pendry can be understood as a van der Waals interaction between two infinite slabs of dielectric material moving relative to each other. Each slab will be aware of the motion of the other because the virtual photons reflected from the moving surface are Doppler-shifted up or down, depending on the direction of the photon wave vector relative to the motion. Pendry shows that this asymmetry in the exchange of virtual photons can lead to an appreciable effect for materials of reasonably strong dispersion. (author)

  13. Random numbers from vacuum fluctuations

    International Nuclear Information System (INIS)

    Shi, Yicheng; Kurtsiefer, Christian; Chng, Brenda

    2016-01-01

    We implement a quantum random number generator based on a balanced homodyne measurement of vacuum fluctuations of the electromagnetic field. The digitized signal is directly processed with a fast randomness extraction scheme based on a linear feedback shift register. The random bit stream is continuously read in a computer at a rate of about 480 Mbit/s and passes an extended test suite for random numbers.

  14. Acceleration of plasma into vacuum

    Energy Technology Data Exchange (ETDEWEB)

    Marshall, John [Los Alamos Scientific Laboratory, University of California, Los Alamos, NM (United States)

    1958-07-01

    The first part of this paper is a discussion of the magnetic acceleration of plasma. The second part contains a description of some experiments which have been performed. In the work reported the intention is: 1. To produce a burst of gas in vacuo; 2. To ionize the gas and heat it to such an extent that it becomes a good electrical conductor. 3. To accelerate the plasma thus produced into vacuum by the use of external time-varying magnetic fields.

  15. Random numbers from vacuum fluctuations

    Energy Technology Data Exchange (ETDEWEB)

    Shi, Yicheng; Kurtsiefer, Christian, E-mail: christian.kurtsiefer@gmail.com [Department of Physics, National University of Singapore, 2 Science Drive 3, Singapore 117542 (Singapore); Center for Quantum Technologies, National University of Singapore, 3 Science Drive 2, Singapore 117543 (Singapore); Chng, Brenda [Center for Quantum Technologies, National University of Singapore, 3 Science Drive 2, Singapore 117543 (Singapore)

    2016-07-25

    We implement a quantum random number generator based on a balanced homodyne measurement of vacuum fluctuations of the electromagnetic field. The digitized signal is directly processed with a fast randomness extraction scheme based on a linear feedback shift register. The random bit stream is continuously read in a computer at a rate of about 480 Mbit/s and passes an extended test suite for random numbers.

  16. Vacuum evaporation of pure metals

    OpenAIRE

    Safarian, Jafar; Engh, Thorvald Abel

    2013-01-01

    Theories on the evaporation of pure substances are reviewed and applied to study vacuum evaporation of pure metals. It is shown that there is good agreement between different theories for weak evaporation, whereas there are differences under intensive evaporation conditions. For weak evaporation, the evaporation coefficient in Hertz-Knudsen equation is 1.66. Vapor velocity as a function of the pressure is calculated applying several theories. If a condensing surface is less than one collision...

  17. Vacuum mammotomy under ultrasound guidance

    International Nuclear Information System (INIS)

    Luczynska, E.; Kocurek, A.; Pawlik, T.; Aniol, J.; Herman, K.; Skotnicki, P.

    2007-01-01

    Breast ultrasound is a non-invasive method of breast examination. You can use it also for fine needle biopsy, core needle biopsy, vacuum mammotomy and for placing the '' wire '' before open surgical biopsy. 106 patients (105 women and 1 man) aged 20-71 years (mean age 46.9) were treated in Cancer Institute in Cracow by vacuum mammotomy under ultrasound guidance. The lesions found in ultrasonography were divided into three groups: benign lesions (BI RADS II), ambiguous lesions (BI RADS 0, III and IVa), and suspicious lesions (BI RADS IV B, IV C and V). Then lesions were qualified to vacuum mammotomy. According to USG, fibroadenoma or '' fibroadenoma-like '' lesions were found in 75 women, in 6 women complicated cysts, in 6 women cyst with dense fluid (to differentiate with FA), and in 19 patients undefined lesions. Fibroadenoma was confirmed in histopathology in 74% patients among patients with fibroadenoma or '' fibroadenoma-like '' lesions in ultrasound (in others also benign lesions were found). Among lesions undefined after ultrasound examination (total 27 patients) cancer was confirmed in 6 % (DCIS and IDC). In 6 patients with complicated cysts in ultrasound examination, histopathology confirmed fibroadenoma in 4 women, an intraductal lesion in 1 woman and inflamatory process in 1 woman. Also in 6 women with a dense cyst or fibroadenoma seen in ultrasound, histopathology confirmed fibroadenoma in 3 women and fibrosclerosis in 3 women. Any breast lesions undefined or suspicious after ultrasound examination should be verified. The method of verification or kind of operation of the whole lesion (vacuum mammotomy or '' wire '') depends on many factors, for example: lesion localization; lesion size; BI RADS category. (author)

  18. QCD contributions to vacuum polarization

    International Nuclear Information System (INIS)

    Reinders, L.J.; Rubinstein, H.R.; Yazaki, S.

    1980-01-01

    We have computed to lowest non-trivial order the perturbative and non-perturbative contributions to the vacuum polarization from all currents up to and including spin 2 ++ . These expressions are important, for example to evaluate QCD sum rules for heavy and light quark systems as shown by Shifman, Vainshtein and Zakharov. Most of the known ones are verified, one slightly changed, and many new ones are displayed. (orig.)

  19. Vacuum vessel for plasma devices

    International Nuclear Information System (INIS)

    Yamada, Masao; Taguchi, Masami.

    1975-01-01

    Object: To permit effective utility of the space in the inner and outer sides of the container wall and also permit repeated assembly for use. Structure: Vacuum vessel wall sections are sealed together by means of welding bellows, and also flange portions formed at the end of the wall sections are coupled together by bolts and are sealed together with a seal ring and a seal cap secured by welding. (Nakamura, S.)

  20. Relaxed plasma-vacuum systems

    International Nuclear Information System (INIS)

    Spies, G.O.; Lortz, D.; Kaiser, R.

    2001-01-01

    Taylor's theory of relaxed toroidal plasmas (states of lowest energy with fixed total magnetic helicity) is extended to include a vacuum between the plasma and the wall. In the extended variational problem, one prescribes, in addition to the helicity and the magnetic fluxes whose conservation follows from the perfect conductivity of the wall, the fluxes whose conservation follows from the assumption that the plasma-vacuum interface is also perfectly conducting (if the wall is a magnetic surface, then one has the toroidal and the poloidal flux in the vacuum). Vanishing of the first energy variation implies a pressureless free-boundary magnetohydrostatic equilibrium with a Beltrami magnetic field in the plasma, and in general with a surface current in the interface. Positivity of the second variation implies that the equilibrium is stable according to ideal magnetohydrodynamics, that it is a relaxed state according to Taylor's theory if the interface is replaced by a wall, and that the surface current is nonzero (at least if there are no closed magnetic field lines in the interface). The plane slab, with suitable boundary conditions to simulate a genuine torus, is investigated in detail. The relaxed state has the same double symmetry as the vessel if, and only if, the prescribed helicity is in an interval that depends on the prescribed fluxes. This interval is determined in the limit of a thin slab

  1. PC driven integrated vacuum system

    International Nuclear Information System (INIS)

    Curuia, Marian; Culcer, Mihai; Brandea, Iulian; Anghel, Mihai

    2001-01-01

    The monitoring of industrial plants by virtual instrumentation represents the most modern trend in the domain of electronic equipment. The integrated vacuum system presented here has several facilities, including the automated data storing of measurement results on hard disk and providing warning messages for operators when the measured parameters are lower or higher upper than the fixed values. The system can also work stand-alone, receiving the commands from the keyboards placed on his front panel but, when it is included in a automation complex system, a remote control from PC is necessary . Both parts of the system, power supply unit for turbo-molecular pump and the vacuum gage, are controlled by an 80C31 microcontroller. Because this microcontroller has a built-in circuitry for a serial communication, we established a serial communication between the PC and the power supply unit for turbo-molecular pump and the vacuum gage, according to the RS-232 hardware standard. As software, after careful evaluation of several options, we chose to develop a hybrid software packing using two different software development tools: LabVIEW, and assembly language. We chose LabVIEW because it is dedicated to data acquisition and communications, containing libraries for data collection, analysis, display and storage. (authors)

  2. Running jobs in the vacuum

    International Nuclear Information System (INIS)

    McNab, A; Stagni, F; Garcia, M Ubeda

    2014-01-01

    We present a model for the operation of computing nodes at a site using Virtual Machines (VMs), in which VMs are created and contextualized for experiments by the site itself. For the experiment, these VMs appear to be produced spontaneously 'in the vacuum' rather having to ask the site to create each one. This model takes advantage of the existing pilot job frameworks adopted by many experiments. In the Vacuum model, the contextualization process starts a job agent within the VM and real jobs are fetched from the central task queue as normal. An implementation of the Vacuum scheme, Vac, is presented in which a VM factory runs on each physical worker node to create and contextualize its set of VMs. With this system, each node's VM factory can decide which experiments' VMs to run, based on site-wide target shares and on a peer-to-peer protocol in which the site's VM factories query each other to discover which VM types they are running. A property of this system is that there is no gate keeper service, head node, or batch system accepting and then directing jobs to particular worker nodes, avoiding several central points of failure. Finally, we describe tests of the Vac system using jobs from the central LHCb task queue, using the same contextualization procedure for VMs developed by LHCb for Clouds.

  3. Ultrahigh energy cosmic ray nuclei from extragalactic pulsars and the effect of their Galactic counterparts

    International Nuclear Information System (INIS)

    Fang, Ke; Olinto, Angela V.; Kotera, Kumiko

    2013-01-01

    The acceleration of ultrahigh energy nuclei in fast spinning newborn pulsars can explain the observed spectrum of ultrahigh energy cosmic rays and the trend towards heavier nuclei for energies above 10 19 eV as reported by the Auger Observatory. Pulsar acceleration implies a hard injection spectrum ( ∼ E −1 ) due to pulsar spin down and a maximum energy E max ∼ Z 10 19 eV due to the limit on the spin rate of neutron stars. We have previously shown that the escape through the young supernova remnant softens the spectrum, decreases slightly the maximum energy, and generates secondary nuclei. Here we show that the distribution of pulsar birth periods and the effect of propagation in the interstellar and intergalactic media modifies the combined spectrum of all pulsars. By assuming a normal distribution of pulsar birth periods centered at 300 ms, we show that the contribution of extragalactic pulsar births to the ultrahigh energy cosmic ray spectrum naturally gives rise to a contribution to very high energy cosmic rays (VHECRs, between 10 16 and 10 18 eV) by Galactic pulsar births. The required injected composition to fit the observed spectrum depends on the absolute energy scale, which is uncertain, differing between Auger Observatory and Telescope Array. The contribution of Galactic pulsar births can also bridge the gap between predictions for cosmic ray acceleration in supernova remnants and the observed spectrum just below the ankle, depending on the composition of the cosmic rays that escape the supernova remnant and the diffusion behavior of VHECRs in the Galaxy

  4. Working in the magnetic field of ultrahigh field MRI

    International Nuclear Information System (INIS)

    Leitgeb, N.; Gombotz, H.

    2013-01-01

    Development of magnetic resonance imaging (MRI) device technology continues to increase the static magnetic flux densities applied and consequently leads to considerably increased occupational exposure. This has already made it necessary to review limits of occupational exposure and to postpone European legal regulations for occupational exposure to electromagnetic fields. This raises the question whether and if so which adverse health effects and health risks might be associated with occupational exposure to MRI ultra-high static magnetic fields. Based on a survey on interaction mechanisms recommendations and safety rules are presented to help minimize adverse health effects of emerging ultra-high field MRI. (orig.) [de

  5. The intergalactic propagation of ultrahigh energy cosmic ray nuclei

    Energy Technology Data Exchange (ETDEWEB)

    Hooper, Dan; /Fermilab; Sarkar, Subir; /Oxford U., Theor. Phys.; Taylor, Andrew M.; /Oxford U.

    2006-08-01

    We investigate the propagation of ultra-high energy cosmic ray nuclei (A = 1-56) from cosmologically distant sources through the cosmic radiation backgrounds. Various models for the injected composition and spectrum and of the cosmic infrared background are studied using updated photodisintegration cross-sections. The observational data on the spectrum and the composition of ultra-high energy cosmic rays are jointly consistent with a model where all of the injected primary cosmic rays are iron nuclei (or a mixture of heavy and light nuclei).

  6. Production of ultrahigh magnetic fields. Technical progress report

    International Nuclear Information System (INIS)

    1985-01-01

    The objective was to produce and measure controlled ultrahigh magnetic fields by imploding a plasma in which a magnetic field has been entrained. The novel method for producing the ultrahigh fields using a gas-puff Z pinch was tested successfully and found to work as well as predicted in some respects and better in others, such as field amplification. Moreover, in testing this concept, we may have created the only megagauss facility in the world with a 3-minute repetition rate and long lifetime. Most megagauss facilities are single-shot, owing to material deformations or the use of explosives

  7. Feature Screening for Ultrahigh Dimensional Categorical Data with Applications.

    Science.gov (United States)

    Huang, Danyang; Li, Runze; Wang, Hansheng

    2014-01-01

    Ultrahigh dimensional data with both categorical responses and categorical covariates are frequently encountered in the analysis of big data, for which feature screening has become an indispensable statistical tool. We propose a Pearson chi-square based feature screening procedure for categorical response with ultrahigh dimensional categorical covariates. The proposed procedure can be directly applied for detection of important interaction effects. We further show that the proposed procedure possesses screening consistency property in the terminology of Fan and Lv (2008). We investigate the finite sample performance of the proposed procedure by Monte Carlo simulation studies, and illustrate the proposed method by two empirical datasets.

  8. Geometric scaling in ultrahigh energy neutrinos and nonlinear perturbative QCD

    International Nuclear Information System (INIS)

    Machado, Magno V.T.

    2011-01-01

    The ultrahigh energy neutrino cross section is a crucial ingredient in the calculation of the event rate in high energy neutrino telescopes. Currently there are several approaches which predict different behaviors for its magnitude for ultrahigh energies. In this contribution is presented a summary of current predictions based on the non-linear QCD evolution equations, the so-called perturbative saturation physics. In particular, predictions are shown based on the parton saturation approaches and the consequences of geometric scaling property at high energies are discussed. The scaling property allows an analytical computation of the neutrino scattering on nucleon/nucleus at high energies, providing a theoretical parameterization. (author)

  9. Shock characterization of an ultra-high strength concrete

    International Nuclear Information System (INIS)

    Erzar, B.; Pontiroli, C.; Buzaud, E.

    2016-01-01

    Nowadays, the design of protective structures may imply ultra-high performance concretes. These materials present a compressive strength 5 times higher than standard concretes. However, few reliable data on the shock response of such materials are available in the literature. Thus, a characterization of an ultra-high strength concrete has been conducted by means of hydrostatic and triaxial tests in the quasi-static regime, and plate impact experiments for shock response. Data have been gathered up to 6 GPa and a simple modelling approach has been applied to get a reliable representation of the shock compression of this concrete. (authors)

  10. CAS CERN Accelerator School vacuum technology. Proceedings

    International Nuclear Information System (INIS)

    Turner, S.

    1999-01-01

    These proceedings present the lectures given at the twelfth specialized course organized by the CERN Accelerator School (CAS), the topic this time being 'Vacuum Technology'. Despite the importance of vacuum technology in the design and operation of particle accelerators at CERN and at the many other accelerators already installed around the world, this was the first time that CAS has organized a course devoted entirely to this topic. Perhaps this reflects the facts that vacuum has become one of the more critical aspects of future accelerators, and that many of the pioneers in the accelerator field are being replaced by new, younger personnel. The lectures start with the basic concepts of the physics and technology of vacuum followed by detailed descriptions of the many different types of gas-pumping devices and methods to measure the pressures achieved. The outgassing characteristics of the different materials used in the construction of vacuum systems and the optimisation of cleaning methods to reduce this outgassing are then explained together with the effects of the residual gases on the particle beams. Then follow chapters on leak detection, materials and vacuum system engineering. Finally, seminars are presented on designing vacuum systems, the history of vacuum devices, the LHC (large hadron collider) vacuum system, vacuum systems for electron storage rings, and quality assurance for vacuum. (orig.)

  11. Rotary bayonets for cryogenic and vacuum service

    International Nuclear Information System (INIS)

    Rucinski, R.A.; Dixon, K.D.; Krasa, R.; Krempetz, K.J.; Mulholland, G.T.; Trotter, G.R.; Urbin, J.B.

    1993-07-01

    Rotary bayonets were designed, tested, and installed for liquid nitrogen, liquid argon, and vacuum service. This paper will present the design, testing, and service record for two sizes of vacuum jacketed cryogenic rotary bayonets and two sizes of vacuum service rotary bayonets. Materials used in construction provide electrical isolation across the bayonet joint. The joint permits 360 degrees of rotation between the male and female pipe sections while maintaining integrity of service. Assemblies using three such joints were built to allow end connection points to be translated through at least 1 meter of horizontal travel while kept in service. Vacuum jacketed sizes built in-house at Fermi National Accelerator Laboratory are 1-1/2 in. inner pipe size, 3 in. vacuum jacket, and 4 in. inner pipe size, 6 in. vacuum jacket The single wall vacuum service bayonets are in 4 in. and 6 in. pipe sizes. The bayonets have successfully been in active service for over one year

  12. Rotary bayonets for cryogenic and vacuum service

    International Nuclear Information System (INIS)

    Rucinski, R.A.; Dixon, K.D.; Krasa, R.; Krempetz, K.J.; Mulholland, G.T.; Trotter, G.R.; Urbin, J.B.

    1994-01-01

    Rotary bayonets were designed, tested, and installed for liquid nitrogen, liquid argon, and vacuum service. This paper will present the design, testing, and service record for two sizes of vacuum jacketed cryogenic rotary bayonets and two sizes of vacuum service rotary bayonets. Materials used in construction provide electrical isolation across the bayonet joint. The joint permits 360 degrees of rotation between the male and female pipe sections while maintaining integrity of service. Assemblies using three such joints were built to allow end connection points to be translated through at least 1 meter of horizontal travel while kept in service. Vacuum jacketed sizes built in-house at Fermi National Accelerator Laboratory are 1 1/2 inches inner pipe size, 3 inches vacuum jacket, and 4 inches inner pipe size, 6 inches vacuum jacket. The single wall vacuum service bayonets are in 4 inch and 6 inch pipe sizes. The bayonets have successfully been in active service for over one year

  13. Ultra-flattened nearly-zero dispersion and ultrahigh nonlinear slot silicon photonic crystal fibers with ultrahigh birefringence

    Science.gov (United States)

    Liao, Jianfei; Xie, Yingmao; Wang, Xinghua; Li, Dongbo; Huang, Tianye

    2017-07-01

    A slot silicon photonic crystal fiber (PCF) is proposed to simultaneously achieve ultrahigh birefringence, large nonlinearity and ultra-flattened nearly-zero dispersion over a wide wavelength range. By taking advantage on the slot effect, ultrahigh birefringence up to 0.0736 and ultrahigh nonlinear coefficient up to 211.48 W-1 m-1 for quasi-TE mode can be obtained at the wavelength of 1.55 μm. Moreover, ultra-flattened dispersion of 0.49 ps/(nm km) for quasi-TE mode can be achieved over a 180 nm wavelength range with low dispersion slope of 1.85 × 10-3 ps/(nm2 km) at 1.55 μm. Leveraging on these advantages, the proposed slot PCF has great potential for efficient all-optical signal processing applications.

  14. Running vacuum cosmological models: linear scalar perturbations

    Energy Technology Data Exchange (ETDEWEB)

    Perico, E.L.D. [Instituto de Física, Universidade de São Paulo, Rua do Matão 1371, CEP 05508-090, São Paulo, SP (Brazil); Tamayo, D.A., E-mail: elduartep@usp.br, E-mail: tamayo@if.usp.br [Departamento de Astronomia, Universidade de São Paulo, Rua do Matão 1226, CEP 05508-900, São Paulo, SP (Brazil)

    2017-08-01

    In cosmology, phenomenologically motivated expressions for running vacuum are commonly parameterized as linear functions typically denoted by Λ( H {sup 2}) or Λ( R ). Such models assume an equation of state for the vacuum given by P-bar {sub Λ} = - ρ-bar {sub Λ}, relating its background pressure P-bar {sub Λ} with its mean energy density ρ-bar {sub Λ} ≡ Λ/8π G . This equation of state suggests that the vacuum dynamics is due to an interaction with the matter content of the universe. Most of the approaches studying the observational impact of these models only consider the interaction between the vacuum and the transient dominant matter component of the universe. We extend such models by assuming that the running vacuum is the sum of independent contributions, namely ρ-bar {sub Λ} = Σ {sub i} ρ-bar {sub Λ} {sub i} . Each Λ i vacuum component is associated and interacting with one of the i matter components in both the background and perturbation levels. We derive the evolution equations for the linear scalar vacuum and matter perturbations in those two scenarios, and identify the running vacuum imprints on the cosmic microwave background anisotropies as well as on the matter power spectrum. In the Λ( H {sup 2}) scenario the vacuum is coupled with every matter component, whereas the Λ( R ) description only leads to a coupling between vacuum and non-relativistic matter, producing different effects on the matter power spectrum.

  15. Ultrahigh-speed, high-sensitivity color camera with 300,000-pixel single CCD

    Science.gov (United States)

    Kitamura, K.; Arai, T.; Yonai, J.; Hayashida, T.; Ohtake, H.; Kurita, T.; Tanioka, K.; Maruyama, H.; Namiki, J.; Yanagi, T.; Yoshida, T.; van Kuijk, H.; Bosiers, Jan T.; Etoh, T. G.

    2007-01-01

    We have developed an ultrahigh-speed, high-sensitivity portable color camera with a new 300,000-pixel single CCD. The 300,000-pixel CCD, which has four times the number of pixels of our initial model, was developed by seamlessly joining two 150,000-pixel CCDs. A green-red-green-blue (GRGB) Bayer filter is used to realize a color camera with the single-chip CCD. The camera is capable of ultrahigh-speed video recording at up to 1,000,000 frames/sec, and small enough to be handheld. We also developed a technology for dividing the CCD output signal to enable parallel, highspeed readout and recording in external memory; this makes possible long, continuous shots up to 1,000 frames/second. As a result of an experiment, video footage was imaged at an athletics meet. Because of high-speed shooting, even detailed movements of athletes' muscles were captured. This camera can capture clear slow-motion videos, so it enables previously impossible live footage to be imaged for various TV broadcasting programs.

  16. Status of Ultra-High Energy Cosmic Rays

    CERN Multimedia

    CERN. Geneva

    2015-01-01

    I will review the recent results on Ultra-High energy cosmic rays obtained by the Auger and Telescope Array Observatories, and discuss some of the Astrophysical scenarios that could account for them, a connection with LHC results  as well as the possible connections to neutrino and gamma ray observations.

  17. Soliton-based ultra-high speed optical communications

    Indian Academy of Sciences (India)

    All these facts are the outcome of research on optical solitons in fibers in spite of the fact that the commonly used RZ format is not always called a soliton format. The overview presented here attempts to incorporate the role of soliton-based communications research in present day ultra-high speed communications.

  18. Oriented nanocomposites of ultrahigh-molecular-weight polyethylene and gold

    NARCIS (Netherlands)

    Heffels, W.; Bastiaansen, C.W.M.; Caseri, W.R.; Smith, P.

    2000-01-01

    Polymer nanocomposites were prepd. by mixing ultrahigh-mol.-wt. polyethylene and gold colloids coated with a self-assembled monolayer of dodecanethiol. Subsequently, these materials were oriented by solid state drawing which induced the formation of uniaxially oriented arrays of gold particles. As a

  19. Proton-proton elastic scattering at ultrahigh energies

    Energy Technology Data Exchange (ETDEWEB)

    Saleem, M.; Shaukat, M.A.; Fazal-e-Aleem (University of the Punjab, Lahore (Pakistan). Dept. of Physics)

    1981-05-30

    The authors use a geometrical model of high-energy pp elastic scattering as proposed by Chou and Yong to analyse experimental data available at present and consider the predictions of the dipole pomeron model for pp elastic scattering at ultrahigh energies. Theoretical results for differential cross sections are compared with experimental data.

  20. Finite escape fraction for ultrahigh energy collisions around Kerr ...

    Indian Academy of Sciences (India)

    Abstract. We investigate the issue of observability of high-energy collisions around Kerr naked singularity and show that results are in contrast with the Kerr black hole case. We had shown that it would be possible to have ultrahigh energy collisions between the particles close to the location r = M around the Kerr naked ...

  1. Finite escape fraction for ultrahigh energy collisions around Kerr

    Indian Academy of Sciences (India)

    We investigate the issue of observability of high-energy collisions around Kerr naked singularity and show that results are in contrast with the Kerr black hole case. We had shown that it would be possible to have ultrahigh energy collisions between the particles close to the location = M around the Kerr naked singularity if ...

  2. Fiber based hydrophones for ultra-high energy neutrino detection

    NARCIS (Netherlands)

    Buis, E.J.; Doppenberg, E.J.J.; Eijk, D. van; Lahmann, R.; Nieuwland, R.A.; Toet, P.M.

    2014-01-01

    It is a well studied process [1, 2] that energy deposition of cosmic ray particles in water that generate thermo-acoustic signals. Hydrophones of sufficient sensitivity could measure this signal and provide a means of detecting ultra-high energetic cosmic neutrinos. We investigate optical

  3. Vacuum Chambers for LEP sections

    CERN Multimedia

    1983-01-01

    The picture shows sections of the LEP vacuum chambers to be installed in the dipole magnets (left) and in the quadrupoles (right). The dipole chamber has three channels: the beam chamber, the pumping duct where the NEG (non-evaporabe getter) is installed and the water channel for cooling (on top in the picture). The pumping duct is connected to the beam chamber through holes in the separating wall. The thick lead lining to shield radiation can also be seen. These chambers were manufactured as extruded aluminium alloy profiles.

  4. Machine for extrusion under vacuum

    International Nuclear Information System (INIS)

    Gautier, A.

    1958-01-01

    In a study of the behaviour of easily oxidised metals during the extrusion process, it is first necessary to find an effective mean of fighting corrosion, since this, even when barely detectable, has an important influence on the validity of the results recorded. The neatest and also the most efficient of all the methods tried consists in creating a vacuum around the test piece. Working on this principle, and at the same time respecting the conventional rules for extrusion tests (loading the sample after stabilisation at the testing temperature, differential measurements of lengthening, etc.) we found it necessary to construct an original machine. (author) [fr

  5. Entanglement in the Bogoliubov vacuum

    DEFF Research Database (Denmark)

    Poulsen, Uffe Vestergaard; Meyer, T.; Lewenstein, M.

    2005-01-01

    We analyze the entanglement properties of the Bogoliubov vacuum, which is obtained as a second-order approximation to the ground state of an interacting Bose-Einstein condensate. We work in one- and two-dimensional lattices and study the entanglement between two groups of sites as a function...... of the geometry of the configuration and the strength of the interactions. As our measure of entanglement we use the logarithmic negativity, supplemented by an algorithmic check for bound entanglement where appropiate. The short-range entanglement is found to grow approximately linearly with the group sizes...

  6. Radiobiological influence of megavoltage electron pulses of ultra-high pulse dose rate on normal tissue cells.

    Science.gov (United States)

    Laschinsky, Lydia; Karsch, Leonhard; Leßmann, Elisabeth; Oppelt, Melanie; Pawelke, Jörg; Richter, Christian; Schürer, Michael; Beyreuther, Elke

    2016-08-01

    Regarding the long-term goal to develop and establish laser-based particle accelerators for a future radiotherapeutic treatment of cancer, the radiobiological consequences of the characteristic short intense particle pulses with ultra-high peak dose rate, but low repetition rate of laser-driven beams have to be investigated. This work presents in vitro experiments performed at the radiation source ELBE (Electron Linac for beams with high Brilliance and low Emittance). This accelerator delivered 20-MeV electron pulses with ultra-high pulse dose rate of 10(10) Gy/min either at the low pulse frequency analogue to previous cell experiments with laser-driven electrons or at high frequency for minimizing the prolonged dose delivery and to perform comparison irradiation with a quasi-continuous electron beam analogue to a clinically used linear accelerator. The influence of the different electron beam pulse structures on the radiobiological response of the normal tissue cell line 184A1 and two primary fibroblasts was investigated regarding clonogenic survival and the number of DNA double-strand breaks that remain 24 h after irradiation. Thereby, no considerable differences in radiation response were revealed both for biological endpoints and for all probed cell cultures. These results provide evidence that the radiobiological effectiveness of the pulsed electron beams is not affected by the ultra-high pulse dose rates alone.

  7. Radiobiological influence of megavoltage electron pulses of ultra-high pulse dose rate on normal tissue cells

    International Nuclear Information System (INIS)

    Laschinsky, Lydia; Karsch, Leonhard; Schuerer, Michael; Lessmann, Elisabeth; Beyreuther, Elke; Oppelt, Melanie; Pawelke, Joerg; Richter, Christian

    2016-01-01

    Regarding the long-term goal to develop and establish laser-based particle accelerators for a future radiotherapeutic treatment of cancer, the radiobiological consequences of the characteristic short intense particle pulses with ultra-high peak dose rate, but low repetition rate of laser-driven beams have to be investigated. This work presents in vitro experiments performed at the radiation source ELBE (Electron Linac for beams with high Brilliance and low Emittance). This accelerator delivered 20-MeV electron pulses with ultra-high pulse dose rate of 10"1"0 Gy/min either at the low pulse frequency analogue to previous cell experiments with laser-driven electrons or at high frequency for minimizing the prolonged dose delivery and to perform comparison irradiation with a quasi-continuous electron beam analogue to a clinically used linear accelerator. The influence of the different electron beam pulse structures on the radiobiological response of the normal tissue cell line 184A1 and two primary fibroblasts was investigated regarding clonogenic survival and the number of DNA double-strand breaks that remain 24 h after irradiation. Thereby, no considerable differences in radiation response were revealed both for biological endpoints and for all probed cell cultures. These results provide evidence that the radiobiological effectiveness of the pulsed electron beams is not affected by the ultra-high pulse dose rates alone. (orig.)

  8. Experience with the TRIUMF Main Tank Vacuum Control System

    International Nuclear Information System (INIS)

    Sarkar, S.; Yandon, J.C.; Sievers, W.; Bennett, P.; Gurd, D.P.; Harmer, P.; Nelson, J.

    1993-01-01

    The TRIUMF Main Tank Vacuum Control System was upgraded in 1984. The earlier system, which consisted of a collection of hardwired relay logic boxes housed in three standard instrumentation racks, was replaced with a compact and flexible microprocessor-based control system. The user interface, previously distributed over the three racks, was consolidated into a single hardwired control and mimic panel. Since 1984, the Main Tank Vacuum System has undergone a series of changes in configuration and vacuum pumping hardware with necessary changes being implemented in the control system logic. Corresponding changes to the user interface were sometimes difficult to implement and in time exhausted the spare input/output capacity which had been built into the panel. The availability of inexpensive personal computers with adequate graphics capability and the ease of modifying, or adding to a programmable user interface precipitated the retirement of the hardwired panel and its replacement by a PC-based graphics user interface. System configuration, safety considerations, the hardware and the software implementation using the open-quote C close-quote programming language are described. The evolution of the control system and its performance, both over the years and in adapting to the vacuum system changes, are discussed

  9. Hamiltonian description of toroidal magnetic fields in vacuum

    International Nuclear Information System (INIS)

    Lewis, H.R.; Bates, J.W.

    1996-01-01

    An investigation of vacuum magnetic fields in toroidal geometry has been initiated. Previously, the general form of the magnetic scalar potential for fields regular at the poloidal axis was given. Here, these results have been expanded to obtain the magnetic scalar potential in a vacuum region that may surround a toroidal current distribution. Using this generalized magnetic scalar potential in conjunction with Boozer's canonical representation of a magnetic field, a field-line Hamiltonian for nonaxisymmetric vacuum fields has been derived. These fields axe being examined using a novel, open-quotes time-dependentclose quotes perturbation theory, which permits the iterative construction of invariants associated with magnetic field-line Hamiltonians that consist of an axisymmetric zeroth-order term, plus a nonaxisymmetric perturbation. By choosing appropriate independent variables, an explicit constructive procedure is developed which involves only a single canonical transformation. Such invariants are of interest because they provide a means of investigating the topology of magnetic field lines. Our objective is to elucidate the existence of magnetic surfaces for nonaxisymmetric vacuum configurations, as well as to provide an approach for studying the onset of stochastic behavior

  10. Imaging at ultrahigh magnetic fields: History, challenges, and solutions.

    Science.gov (United States)

    Uğurbil, Kamil

    2018-03-01

    Following early efforts in applying nuclear magnetic resonance (NMR) spectroscopy to study biological processes in intact systems, and particularly since the introduction of 4 T human scanners circa 1990, rapid progress was made in imaging and spectroscopy studies of humans at 4 T and animal models at 9.4 T, leading to the introduction of 7 T and higher magnetic fields for human investigation at about the turn of the century. Work conducted on these platforms has provided numerous technological solutions to challenges posed at these ultrahigh fields, and demonstrated the existence of significant advantages in signal-to-noise ratio and biological information content. Primary difference from lower fields is the deviation from the near field regime at the radiofrequencies (RF) corresponding to hydrogen resonance conditions. At such ultrahigh fields, the RF is characterized by attenuated traveling waves in the human body, which leads to image non-uniformities for a given sample-coil configuration because of destructive and constructive interferences. These non-uniformities were initially considered detrimental to progress of imaging at high field strengths. However, they are advantageous for parallel imaging in signal reception and transmission, two critical technologies that account, to a large extend, for the success of ultrahigh fields. With these technologies and improvements in instrumentation and imaging methods, today ultrahigh fields have provided unprecedented gains in imaging of brain function and anatomy, and started to make inroads into investigation of the human torso and extremities. As extensive as they are, these gains still constitute a prelude to what is to come given the increasingly larger effort committed to ultrahigh field research and development of ever better instrumentation and techniques. Copyright © 2017 Elsevier Inc. All rights reserved.

  11. Vacuum systems for the ILC helical undulator

    CERN Document Server

    Malyshev, O B; Clarke, J A; Bailey, I R; Dainton, J B; Malysheva, L I; Barber, D P; Cooke, P; Baynham, E; Bradshaw, T; Brummitt, A; Carr, S; Ivanyushenkov, Y; Rochford, J; Moortgat-Pick, G A

    2007-01-01

    The International Linear Collider (ILC) positron source uses a helical undulator to generate polarized photons of ∼10MeV∼10MeV at the first harmonic. Unlike many undulators used in synchrotron radiation sources, the ILC helical undulator vacuum chamber will be bombarded by photons, generated by the undulator, with energies mostly below that of the first harmonic. Achieving the vacuum specification of ∼100nTorr∼100nTorr in a narrow chamber of 4–6mm4–6mm inner diameter, with a long length of 100–200m100–200m, makes the design of the vacuum system challenging. This article describes the vacuum specifications and calculations of the flux and energy of photons irradiating the undulator vacuum chamber and considers possible vacuum system design solutions for two cases: cryogenic and room temperature.

  12. Straw detector: 1 - Vacuum: 0

    CERN Multimedia

    Katarina Anthony

    2012-01-01

    The NA62 straw tracker is using pioneering CERN technology to measure charged particles from very rare kaon decays. For the first time, a large straw tracker with a 4.4 m2 coverage will be placed directly into an experiment’s vacuum tank, allowing physicists to measure the direction and momentum of charged particles with extreme precision. NA62 measurements using this technique will help physicists take a clear look at the kaon decay rate, which might be influenced by particles and processes that are not included in the Standard Model.   Straw ends are glued to an aluminium frame, a crucial step in the assembly of a module. The ends are then visually inspected before a leak test is performed.  “Although straw detectors have been around since the 1980s, what makes the NA62 straw trackers different is that they can work under vacuum,” explains Hans Danielsson from the PH-DT group leading the NA62 straw project. Straw detectors are basically small drift cha...

  13. High-vacuum plasma pump

    International Nuclear Information System (INIS)

    Dorodnov, A.M.; Minajchev, V.E.; Miroshkin, S.I.

    1980-01-01

    The action of an electric-arc high-vacuum pump intended for evacuating the volumes in which the operation processes are followed by a high gas evolution is considered. The operation of the pump is based on the principle of controlling the getter feed according to the gas load and effect of plasma sorbtion pumping. The pump performances are given. The starting pressure is about 5 Pa, the limiting residual pressure is about 5x10 -6 Pa, the pumping out rate of nitrogen in the pressure range 5x10 -5 -5x10 -3 Pa accounts for about 4000 l/s, the power consumption comes to 6 kW. Analyzing the results of the test operation of the pump, it has been concluded that its principal advantages are the high starting pressure, controlled getter feed rate and possibility of pumping out the gases which are usually pumped out with difficulty. The operation reliability of the pump is defined mainly by reliable operation of the ignition system of the vacuum arc [ru

  14. Gases vacuum dedusting and cooling

    Directory of Open Access Journals (Sweden)

    Alexey А. Burov

    2015-03-01

    Full Text Available Represented are the results of operating the ladle degassing vacuum plant (productivity: 120 tons of liquid steel with various dust collectors. The process gases’ cooling and dedusting, obtained in the closed loop buran study, provides opportunity to install a bag filter after that closed loop and its efficient use. Proven is the effectiveness of the cylindrical cyclone replacement with a multichannel (buran dust collector, based on a system of closed-loop (return coupling serially connected curved ducts, where the dusty gas flow rotation axis is vertically positioned. The system of closed-loop serially connected curvilinear channels creates preconditions for the emergence of a negative feedback at the curvilinear gas flow containing transit and circulating flows. These conditions are embodied with circulating flows connecting the in- and outputs of the whole system each channel. The transit flow multiple continuous filtration through the circulating dust layers leads to the formation and accumulation of particles aggregates in the collection chamber. The validity of such a dusty flow control mechanism is confirmed by experimental data obtained in a vacuum chamber. Therefore, replacing one of the two buran’s forevacuum pumps assemblies with the necessary number of curved channels (closed loop is estimated in a promising method.

  15. TORE SUPRA vacuum vessel and shield manufacturing

    International Nuclear Information System (INIS)

    Blateyron, J.; Lepez, R.

    1984-01-01

    TORE SUPRA vacuum vessel and vacuum chamber shield manufacturing in progress at Jeumont-Schneider consists of three main phases: - Detail engineering and manufacturing fixture construction; - Prototype section manufacturing and process preparation; - Construction of the 6 production modules. The welding techniques adopted, call for three special automatic processes: TIG, MIG and PLASMA welding which guarantee mechanical strength, vacuum tightness and absence of distortion. Production of the modules began July 1984. (author)

  16. A versatile ultra high vacuum sample stage with six degrees of freedom

    Energy Technology Data Exchange (ETDEWEB)

    Ellis, A. W.; Tromp, R. M. [IBM T.J. Watson Research Center, 1101 Kitchawan Road, P.O. Box 218, Yorktown Heights, New York 10598 (United States)

    2013-07-15

    We describe the design and practical realization of a versatile sample stage with six degrees of freedom. The stage was designed for use in a Low Energy Electron Microscope, but its basic design features will be useful for numerous other applications. The degrees of freedom are X, Y, and Z, two tilts, and azimuth. All motions are actuated in an ultrahigh vacuum base pressure environment by piezoelectric transducers with integrated position sensors. The sample can be load-locked. During observation, the sample is held at a potential of −15 kV, at temperatures between room temperature and 1500 °C, and in background gas pressures up to 1 × 10{sup −4} Torr.

  17. Tribological Performance of Some Pennzane(Registered Trademark) Based Greases for Vacuum Applications

    Science.gov (United States)

    Marchetti, Mario; Jones, William R., Jr.; Street, Kenneth W.; Wheeler, Donald; Dixon, Duane; Jansen, Mark J.; Kimura, Hiroshi

    2002-01-01

    Commercial greases for space applications usually fulfill the requirements imposed by the severe conditions of use. The main requirement is their ability to create an EHL film, boundary film, or both under speed, load and temperature conditions that the mechanisms will operate. Three greases, all based on a multiply alkylated cyclopentane (Pennzan(R)) base oil, were studied. The thickeners were an n-octadecylterephthalamate soap, a lithium soap, and a urea derivative. A Four-Ball Tribometer and a Spiral Orbit Tribometer were employed to evaluate the greases under ultrahigh vacuum. Results indicated that all three greases yielded very low wear rates and extended lifetimes. In addition, routine physical property data is reported for each grease.

  18. Shape Memory Alloy connectors for Ultra High Vacuum applications: a breakthrough for accelerator technologies

    CERN Document Server

    AUTHOR|(CDS)2091326; Garion, Cedric

    Beam-pipe coupling in particle accelerators is nowadays provided by metallic flanges that are tightly connected by several screws or heavy collars. Their installation and dismounting in radioactive areas contribute to the radiation doses received by the technical personnel. Owing to the increased proton-beam intensity and luminosity of the future High-Luminosity LHC (HL-LHC), radioactivity in some specific zones will be significantly higher than in the present LHC; the presence of the technical staff in these areas will be strictly controlled and minimized. Remote interventions are being considered, too. Shape Memory Alloys (SMAs) offer a unique possibility to generate tight connections and fast clamping/unclamping by remotely changing the temperature of the junction unit. In fact, SMAs exhibit unique strain and stress recovery capabilities which are related to reversible phase transition mechanisms, induced thermally or mechanically. In this PhD work, a novel Ultra-High Vacuum (UHV) coupling system based on ...

  19. Vacuum technology in the chemical industry

    CERN Document Server

    Jorisch, Wolfgang

    2015-01-01

    Based on the very successful German edition and a seminar held by the German Engineers` Association (VDI) on a regular basis for years now, this English edition has been thoroughly updated and revised to reflect the latest developments. It supplies in particular the special aspects of vacuum technology, applied vacuum pump types and vacuum engineering in the chemical, pharmaceutical and process industry application-segments. The text includes chapters dedicated to latest European regulations for operating in hazardous zones with vacuum systems, methods for process pressure control and regulati

  20. Development of a vacuum superinsulation panel

    Energy Technology Data Exchange (ETDEWEB)

    Timm, H; Seefeldt, D; Nitze, C

    1983-05-01

    After completion of the investigations the vacuum-insulated panel is available as prototype. The aim of the investigations was to optimize and to finalize the vacuum superinsulation system with regard to a pressure-resistant, temperature-resistant thermal insulation of high efficiency. In this connection, particularly investigations with regard to vacuum-tight sealing, compression and evacuation of powder filling as well as special material investigations were performed. The application-specific utilization of the vacuum-insulated panel and the adjustment to special operational conditions can now be started. Application possibilities are at present seen in coverings or linings with high temperature and/or pressure requirements.

  1. Dynamical effects of QCD vacuum structure

    International Nuclear Information System (INIS)

    Ferreira, Erasmo

    1994-01-01

    The role of the QCD vacuum structure in the determination of the properties of states and processes occurring in the confinement regime of QCD is reviewed. The finite range of the vacuum correlations is discussed, and an analytical form is suggested for the correlation functions. The role of the vacuum quantum numbers in the phenomenology of high-energy scattering is reviewed. The vacuum correlation model of non-perturbative QCD is mentioned as a bridge between the fundamental theory and the description of the experiments. (author). 13 refs., 1 fig

  2. Cold vacuum drying facility design requirements

    International Nuclear Information System (INIS)

    IRWIN, J.J.

    1999-01-01

    This document provides the detailed design requirements for the Spent Nuclear Fuel Project Cold Vacuum Drying Facility. Process, safety, and quality assurance requirements and interfaces are specified

  3. Vacuum exhaust duct used for thermonuclear device

    International Nuclear Information System (INIS)

    Tachikawa, Nobuo; Kondo, Mitsuaki; Honda, Tsutomu.

    1990-01-01

    The present invention concerns a vacuum exhaust duct used for a thermonuclear device. A cylindrical metal liners is lined with a gap to the inside of a vacuum exhaust duct main body. Bellows are connected to both ends of the metal liners and the end of the bellows is welded to the vacuum exhaust duct main body. Futher, a heater is mounted to the metal liner on the side of the vacuum exhaust duct main body, and the metal liner is heated by the heater to conduct baking for the vacuum exhaust duct main body. Accordingly, since there is no requirement for elevating the temperature of the vacuum exhaust duct upon conducting baking, the vacuum exhaust duct scarcely suffers substantial deformation due to heat expansion. Further, there is also no substantial deformation for the bellows disposed between the outer circumference of the vacuum vessel and a portion of a vacuum exhaust duct, so that the durability of the bellows is greatly improved. (I.S.)

  4. Evacuation of the NET vacuum chamber

    International Nuclear Information System (INIS)

    Muller, R.A.

    1987-01-01

    Parametric calculations of the evacuation process were carried out for the NET-vacuum chamber involving two blanket designs. The results show that with an acceptable vacuum pumping capacity the required start vacuum conditions can be realized within reasonable time. The two blanket concepts do not differ remarkably in their evacuation behaviour. The remaining large pressure differences between the different locations of the vacuum chamber can be reduced if approximately 30% of the total gas flow is extracted from the heads of the blanket replacement ports

  5. Evacuation of the NET vacuum chamber

    International Nuclear Information System (INIS)

    Mueller, R.

    1986-01-01

    Parametric calculations of the evacuation process were carried out for the NET-vacuum chamber involving two blanket designs. The results show that with an acceptable vacuum pumping capacity the required start vacuum conditions can be realized within reasonable time. The two blanket concepts do not differ remarkably in their evacuation behaviour. The remaining large pressure differences between the different locations of the vacuum chamber can be reduced if approximately 30% of the total gas flow is extracted from the heads of the blanket replacement ports. (author)

  6. Cold vacuum drying facility design requirements

    Energy Technology Data Exchange (ETDEWEB)

    IRWIN, J.J.

    1999-07-01

    This document provides the detailed design requirements for the Spent Nuclear Fuel Project Cold Vacuum Drying Facility. Process, safety, and quality assurance requirements and interfaces are specified.

  7. IN VITRO FLOW ANALYSIS OF NOVEL DOUBLE-CUTTING, OPEN-PORT, ULTRAHIGH-SPEED VITRECTOMY SYSTEMS.

    Science.gov (United States)

    Zehetner, Claus; Moelgg, Marion; Bechrakis, Emmanouil; Linhart, Caroline; Bechrakis, Nikolaos E

    2017-10-09

    To analyze the performance and flow characteristics of novel double-cutting, open-port, 23-, 25-, and 27-gauge ultrahigh-speed vitrectomy systems. In vitro fluidic measurements were performed to assess the volumetric aspiration profiles of several vitrectomy systems in basic salt solution and egg white. Double-cutting open-port vitrectomy probes delivered stable aspiration flow rates that were less prone to flow variation affected by the cutting speed. Increase in cutting frequency to the maximum level resulted in flow reduction of less than 10% (0.0%-9.5%). Commercially available 23-, 25-, and 27-G double-cutting probes exhibited higher egg-white and basic salt solution flow rates at all evaluated cut rates, with aspirational efficiencies being 1.1 to 2.9 times the flow rates of standard single-blade vitrectomy probes of the same caliber at the maximum preset vacuum. The highest relative differences were observed at faster cut rates. The newly introduced double-cutting open-port vitrectomy probes delivered stable aspiration flow rates that were less prone to flow variation affected by the cutting speed. The fluidic principle of constant flow even at the highest cut rates and low vacuum levels might impact surgical strategies, especially when performing manipulations close to the retina.

  8. Wafer-level hermetic vacuum packaging by bonding with a copper-tin thin film sealing ring

    Science.gov (United States)

    Akashi, Teruhisa; Funabashi, Hirofumi; Takagi, Hideki; Omura, Yoshiteru; Hata, Yoshiyuki

    2018-04-01

    A wafer-level hermetic vacuum packaging technology intended for use with MEMS devices was developed based on a copper-tin (CuSn) thin film sealing ring. To allow hermetic packaging, the shear strength of the CuSn thin film bond was improved by optimizing the pretreatment conditions. As a result, an average shear strength of 72.3 MPa was obtained and a cavity that had been hermetically sealed using wafer-level packaging (WLP) maintained its vacuum for 1.84 years. The total pressures in the cavities and the partial pressures of residual gases were directly determined with an ultra-low outgassing residual gas analyzer (RGA) system. Hermeticity was evaluated based on helium leak rates, which were calculated from helium pressures determined with the RGA system. The resulting data showed that a vacuum cavity following 1.84 years storage had a total pressure of 83.1 Pa, contained argon as the main residual gas and exhibited a helium leak rate as low as 1.67  ×  10-17 Pa · m3 s-1, corresponding to an air leak rate of 6.19  ×  10-18 Pa · m3 s-1. The RGA data demonstrate that WLP using a CuSn thin film sealing ring permits ultra-high hermeticity in conjunction with long-term vacuum packaging that is applicable to MEMS devices.

  9. Construction of a Thermal Vacuum Chamber for Environment Test of Triple CubeSat Mission TRIO-CINEMA

    Science.gov (United States)

    Jeon, Jeheon; Lee, Seongwhan; Yoon, Seyoung; Seon, Jongho; Jin, Ho; Lee, Donghun; Lin, Robert P.

    2013-12-01

    TRiplet Ionospheric Observatory-CubeSat for Ion, Neutron, Electron & MAgnetic fields (TRIO-CINEMA) is a CubeSat with 3.14 kg in weight and 3-U (10 × 10 × 30 cm) in size, jointly developed by Kyung Hee University and UC Berkeley to measure magnetic fields of near Earth space and detect plasma particles. When a satellite is launched into orbit, it encounters ultrahigh vacuum and extreme temperature. To verify the operation and survivability of the satellite in such an extreme space environment, experimental tests are conducted on the ground using thermal vacuum chamber. This paper describes the temperature control device and monitoring system suitable for CubeSat test environment using the thermal vacuum chamber of the School of Space Research, Kyung Hee University. To build the chamber, we use a general purpose thermal analysis program and NX 6.0 TMG program. We carry out thermal vacuum tests on the two flight models developed by Kyung Hee University based on the thermal model of the TRIO-CINEMA satellite. It is expected from this experiment that proper operation of the satellite in the space environment will be achieved.

  10. Construction of a Thermal Vacuum Chamber for Environment Test of Triple CubeSat Mission TRIO-CINEMA

    Directory of Open Access Journals (Sweden)

    Jeheon Jeon

    2013-09-01

    Full Text Available TRiplet Ionospheric Observatory-CubeSat for Ion, Neutron, Electron & MAgnetic fields (TRIO-CINEMA is a CubeSat with 3.14 kg in weight and 3-U (10 × 10 × 30 cm in size, jointly developed by Kyung Hee University and UC Berkeley to measure magnetic fields of near Earth space and detect plasma particles. When a satellite is launched into orbit, it encounters ultrahigh vacuum and extreme temperature. To verify the operation and survivability of the satellite in such an extreme space environment, experimental tests are conducted on the ground using thermal vacuum chamber. This paper describes the temperature control device and monitoring system suitable for CubeSat test environment using the thermal vacuum chamber of the School of Space Research, Kyung Hee University. To build the chamber, we use a general purpose thermal analysis program and NX 6.0 TMG program. We carry out thermal vacuum tests on the two flight models developed by Kyung Hee University based on the thermal model of the TRIO-CINEMA satellite. It is expected from this experiment that proper operation of the satellite in the space environment will be achieved.

  11. Advanced light source vacuum policy and vacuum guidelines for beamlines and experiment endstations

    International Nuclear Information System (INIS)

    Hussain, Z.

    1995-08-01

    The purpose of this document is to: (1) Explain the ALS vacuum policy and specifications for beamlines and experiment endstations. (2) Provide guidelines related to ALS vacuum policy to assist in designing beamlines which are in accordance with ALS vacuum policy. This document supersedes LSBL-116. The Advanced Light Source is a third generation synchrotron radiation source whose beam lifetime depends on the quality of the vacuum in the storage ring and the connecting beamlines. The storage ring and most of the beamlines share a common vacuum and are operated under ultra-high-vacuum (UHV) conditions. All endstations and beamline equipment must be operated so as to avoid contamination of beamline components, and must include proper safeguards to protect the storage ring vacuum from an accidental break in the beamline or endstation vacuum systems. The primary gas load during operation is due to thermal desorption and electron/photon induced desorption of contaminants from the interior of the vacuum vessel and its components. The desorption rates are considerably higher for hydrocarbon contamination, thus considerable emphasis is placed on eliminating these sources of contaminants. All vacuum components in a beamline and endstation must meet the ALS vacuum specifications. The vacuum design of both beamlines and endstations must be approved by the ALS Beamline Review Committee (BRC) before vacuum connections to the storage ring are made. The vacuum design is first checked during the Beamline Design Review (BDR) held before construction of the beamline equipment begins. Any deviation from the ALS vacuum specifications must be approved by the BRC prior to installation of the equipment on the ALS floor. Any modification that is incorporated into a vacuum assembly without the written approval of the BRC is done at the user's risk and may lead to rejection of the whole assembly

  12. Dynamics of vacuum-sealed, double-leaf partitions

    Science.gov (United States)

    Kavanaugh, Joshua Stephen

    The goal of this research is to investigate the feasibility and potential effectiveness of using vacuum-sealed, double-leaf partitions for applications in noise control. Substantial work has been done previously on double-leaf partitions where the acoustics of the inner chamber and mechanical vibrations of structural supports are passively and actively controlled. The work presented here is unique in that the proposed system aims to eliminate the need for active acoustic control of transmitted acoustic energy by removing all the air between the two panels of the double partition. Therefore, the only remaining energy paths would be along the boundary and at the points where there are intermediate structural supports connecting the two panels. The eventual goal of the research is to develop a high-loss double-leaf partition that simplifies active control by removing the need for control of the air cavity and channeling all the energy into discrete structural paths. The work presented here is a first step towards the goal of designing a high-loss, actively-controlled double-leaf partition with an air-evacuated inner chamber. One experiment is conducted to investigate the effects of various levels of vacuum on the response of a double-leaf partition whose panels are mechanically coupled only at the boundary. Another experiment is conducted which investigates the effect of changing the stiffness of an intermediate support coupling the two panels of a double-leaf partition in which a vacuum has been applied to the inner cavity. The available equipment was able to maintain a 99% vacuum between the panels. Both experiments are accompanied by analytical models used to investigate the importance of various dynamic parameters. Results show that the vacuum-sealed system shows some potential for increased transmission loss, primarily by the changing the natural frequencies of the double-leaf partition.

  13. Fusion reactor high vacuum pumping

    International Nuclear Information System (INIS)

    Sedgley, D.W.; Walthers, C.R.; Jenkins, E.M.

    1992-01-01

    This paper reports on recent experiments which have shown the practicality of using activated carbon (coconut charcoal) at 4K to pump helium and hydrogen isotopes for a fusion reactor. Both speed and capacity for deuterium/helium and tritium/helium-3 mixtures were satisfactory. The long-term effects of tritium on the charcoal/cement system developed by Grumman and LLNL was now known; therefore a program was undertaken to see what, if any, effect long-term tritium exposure has on the cryosorber. Several charcoal on aluminum test samples were subjected to six months exposure of tritium at approximately 77 K. The tritium was scanned several times with a residual gas analyzer and the speed-capacity performance of the samples was measured before, approximately one-third way through, and after the exposure. Modest effects were noted which would not seriously restrict the use of charcoal as a cryosorber for fusion reactor high-vacuum pumping applications

  14. Progress of ITER vacuum vessel

    Energy Technology Data Exchange (ETDEWEB)

    Ioki, K., E-mail: Kimihiro.Ioki@iter.org [ITER Organization, Route de Vinon sur Verdon, 13115 St Paul-lez-Durance (France); Bayon, A. [F4E, c/ Josep Pla, No. 2, Torres Diagonal Litoral, Edificio B3, E-08019 Barcelona (Spain); Choi, C.H.; Daly, E.; Dani, S.; Davis, J.; Giraud, B.; Gribov, Y.; Hamlyn-Harris, C.; Jun, C.; Levesy, B. [ITER Organization, Route de Vinon sur Verdon, 13115 St Paul-lez-Durance (France); Kim, B.C. [NFRI, 52 Yeoeundong Yuseonggu, Daejeon 305-333 (Korea, Republic of); Kuzmin, E. [NTC “Sintez”, Efremov Inst., 189631 Metallostroy, St. Petersburg (Russian Federation); Le Barbier, R.; Martinez, J.-M. [ITER Organization, Route de Vinon sur Verdon, 13115 St Paul-lez-Durance (France); Pathak, H. [ITER-India, A-29, GIDC Electronic Estate, Sector 25, Gandhinagar 382025 (India); Preble, J. [ITER Organization, Route de Vinon sur Verdon, 13115 St Paul-lez-Durance (France); Sa, J.W. [NFRI, 52 Yeoeundong Yuseonggu, Daejeon 305-333 (Korea, Republic of); Terasawa, A.; Utin, Yu. [ITER Organization, Route de Vinon sur Verdon, 13115 St Paul-lez-Durance (France); and others

    2013-10-15

    Highlights: ► This covers the overall status and progress of the ITER vacuum vessel activities. ► It includes design, R and D, manufacturing and approval process of the regulators. ► The baseline design was completed and now manufacturing designs are on-going. ► R and D includes ISI, dynamic test of keys and lip-seal welding/cutting technology. ► The VV suppliers produced full-scale mock-ups and started VV manufacturing. -- Abstract: Design modifications were implemented in the vacuum vessel (VV) baseline design in 2011–2012 for finalization. The modifications are mostly due to interface components, such as support rails and feedthroughs for the in-vessel coils (IVC). Manufacturing designs are being developed at the domestic agencies (DAs) based on the baseline design. The VV support design was also finalized and tests on scale mock-ups are under preparation. Design of the in-wall shielding (IWS) has progressed, considering the assembly methods and the required tolerances. Further modifications are required to be consistent with the DAs’ manufacturing designs. Dynamic tests on the inter-modular and stub keys to support the blanket modules are being performed to measure the dynamic amplification factor (DAF). An in-service inspection (ISI) plan has been developed and R and D was launched for ISI. Conceptual design of the VV instrumentation has been developed. The VV baseline design was approved by the agreed notified body (ANB) in accordance with the French Nuclear Pressure Equipment Order procedure.

  15. The physics of ''vacuum'' breakdown

    International Nuclear Information System (INIS)

    Schwirzke, F.

    1993-01-01

    Many discharges form small cathode spots which provide such a high energy density that the cathode material explodes into a dense plasma cloud within a very short time. Despite the fundamental importance of cathode spots for the breakdown process and the formation of a discharge, the structure of the cathode spot plasma and the source of the high energy density were not yet well defined. One model, the whisker explosive emission model, assumes that joule heating by field emitted electrons provides the energy. Current densities of j FE = 10 12 - 10 13 A/m 2 would be required. However, the pre-breakdown j FE is self-limiting. The negative space charge caused by j FE in the cathode-anode gap reduces the effective electric field E on the cathode surface. The maximum current density j CL is space charge limited by Child-Langmuir's law. The field emitting spot cannot deliver j CL without turning itself off, since the negative space charge caused by j CL reduces E congruent 0 at the cathode surface. Hence, it must be that the vacuum j FE CL . The development of a current with j > j FE (vacuum) requires that ions exist in front of the electron emitting spot. Ions cannot be emitted from the surface of the field emitting spot, the enhanced electric field would hold them back. The initial ionization must occur in the cathode-anode gap near the electron emitting spot. Ionization of desorbed neutrals provides the mechanism. This ionization process requires considerably less current than the ionization of solid material by joule heating. Field emission and the impact of ions stimulate desorption of weakly bound adsorbates from the surface of the electron emitting spot. The cross section for ionization of the neutrals has a maximum for ∼ 100 eV electrons

  16. Vacuum ultraviolet photochemistry of polymers

    International Nuclear Information System (INIS)

    Skurat, Vladimir

    2003-01-01

    The interaction of vacuum UV radiation (wavelength range from 1 to 200 nm) with polymers is interesting for fundamental and applied sciences. This interest is stimulated by various reasons: - Wide applications of polymeric materials in semiconductor technology, where they are used as photoresist materials in combination with VUV light sources (lasers, excimer lamps, synchrotron radiation and others). - Polymers are widely used as spacecraft materials in the last 20 years. On near-Earth orbits, the polymeric materials of spacecraft surfaces are destroyed by solar radiation. - VUV radiation is one of the components of gas discharge plasmas, which are used for treatment of polymer, with the aim of modifying their surface properties. The main features of interaction of VUV radiation with polymers are discussed. The spectra of intrinsic absorption of saturated polymers (polyethylene, polypropylene, polytetrafluoroethylene and others) are situated mainly in the VUV region. The photochemistry of polymers in the VUV region is very different from their photochemistry at wavelengths longer than 200 nm, where the absorption spectra belong to impurities and polymer defects. The polymer photochemistry in the VUV region is wavelength-dependent. At wavelengths longer than about 140 nm, the main role is played by transformations of primary-formed singlet excited molecules. At shorter wavelengths the role of photoionization increases progressively and the main features of VUV photolysis become similar to the picture of radiolysis, with significant contributions of charge pairs and triplet excited molecules. Very important features of VUV light absorption in polymers are high absorption coefficients. Because of this, the surface layers absorb large doses of energy. This leads to very profound transformation of material on the polymer surface. In particular for polymers which are considered destroyed by radiation (for example, perfluoropolymers), this leads to VUV-induced erosion

  17. Progress of ITER vacuum vessel

    International Nuclear Information System (INIS)

    Ioki, K.; Bayon, A.; Choi, C.H.; Daly, E.; Dani, S.; Davis, J.; Giraud, B.; Gribov, Y.; Hamlyn-Harris, C.; Jun, C.; Levesy, B.; Kim, B.C.; Kuzmin, E.; Le Barbier, R.; Martinez, J.-M.; Pathak, H.; Preble, J.; Sa, J.W.; Terasawa, A.; Utin, Yu.

    2013-01-01

    Highlights: ► This covers the overall status and progress of the ITER vacuum vessel activities. ► It includes design, R and D, manufacturing and approval process of the regulators. ► The baseline design was completed and now manufacturing designs are on-going. ► R and D includes ISI, dynamic test of keys and lip-seal welding/cutting technology. ► The VV suppliers produced full-scale mock-ups and started VV manufacturing. -- Abstract: Design modifications were implemented in the vacuum vessel (VV) baseline design in 2011–2012 for finalization. The modifications are mostly due to interface components, such as support rails and feedthroughs for the in-vessel coils (IVC). Manufacturing designs are being developed at the domestic agencies (DAs) based on the baseline design. The VV support design was also finalized and tests on scale mock-ups are under preparation. Design of the in-wall shielding (IWS) has progressed, considering the assembly methods and the required tolerances. Further modifications are required to be consistent with the DAs’ manufacturing designs. Dynamic tests on the inter-modular and stub keys to support the blanket modules are being performed to measure the dynamic amplification factor (DAF). An in-service inspection (ISI) plan has been developed and R and D was launched for ISI. Conceptual design of the VV instrumentation has been developed. The VV baseline design was approved by the agreed notified body (ANB) in accordance with the French Nuclear Pressure Equipment Order procedure

  18. Measurement uncertainties for vacuum standards at Korea Research Institute of Standards and Science

    International Nuclear Information System (INIS)

    Hong, S. S.; Shin, Y. H.; Chung, K. H.

    2006-01-01

    The Korea Research Institute of Standards and Science has three major vacuum systems: an ultrasonic interferometer manometer (UIM) (Sec. II, Figs. 1 and 2) for low vacuum, a static expansion system (SES) (Sec. III, Figs. 3 and 4) for medium vacuum, and an orifice-type dynamic expansion system (DES) (Sec. IV, Figs. 5 and 6) for high and ultrahigh vacuum. For each system explicit measurement model equations with multiple variables are, respectively, given. According to ISO standards, all these system variable errors were used to calculate the expanded uncertainty (U). For each system the expanded uncertainties (k=1, confidence level=95%) and relative expanded uncertainty (expanded uncertainty/generated pressure) are summarized in Table IV and are estimated to be as follows. For UIM, at 2.5-300 Pa generated pressure, the expanded uncertainty is -2 Pa and the relative expanded uncertainty is -2 ; at 1-100 kPa generated pressure, the expanded uncertainty is -5 . For SES, at 3-100 Pa generated pressure, the expanded uncertainty is -1 Pa and the relative expanded uncertainty is -3 . For DES, at 4.6x10 -3 -1.3x10 -2 Pa generated pressure, the expanded uncertainty is -4 Pa and the relative expanded uncertainty is -3 ; at 3.0x10 -6 -9.0x10 -4 Pa generated pressure, the expanded uncertainty is -6 Pa and the relative expanded uncertainty is -2 . Within uncertainty limits our bilateral and key comparisons [CCM.P-K4 (10 Pa-1 kPa)] are extensive and in good agreement with those of other nations (Fig. 8 and Table V)

  19. Multifunctional Ultra-High Vacuum Apparatus for Studies of the Interactions of Chemical Warfare Agents on Complex Surfaces

    Science.gov (United States)

    2014-01-02

    How- ever, the complete absence of trace amounts of CWAs from the system is never guaranteed. Therefore, prior to venting the chamber and opening a...Gay, A. J. McFarlan, and B. A. Morrow, “Trimethyl phosphite ad- sorbed on silica - An NMR and infrared study,” J. Phys. Chem. 95(3), 1360–1368 (1991

  20. Ultra-high vacuum qualification of the prototype module for the 2*3 km arms of the VIRGO interferometer

    CERN Document Server

    Brisson, V; Lissilour, G; Marin, P; Reboux, A; Bernardini, B; Pasqualetti, A

    2001-01-01

    The prototype for the series production of the 400 modules to be built by CNIM is first briefly described after the surface cleaning and 400 degrees C air firing. The systems for the 160 degrees C bake out, the pumping and measuring bench installed in the CNIM premises are then presented. The results on leak tightness, hydrogen outgassing and residual hydrocarbon contamination are reported and compared to the 20 degrees C VIRGO specifications. An additional test on hydrogen diffusion at 400 degrees C performed at CERN on a stainless-steel sample is reported. Our measurement of the hydrogen outgassing rate is discussed in relation with this test and also with regard to the oxide layer resulting from the air firing. (5 refs).

  1. Multifunctional Ultra-high Vacuum Apparatus for Studies of the Interactions of Chemical Warfare Agents on Complex Surfaces

    Science.gov (United States)

    2014-01-02

    ion gun, (M) Venturi tube ventilation system, (N) foreline pumps for all the turbomolecular pumps . plished from a source containing no more than...via hot gas and pumping cycles prior to removal of any flange; and (5) The entire chamber must be maintained under negative pressure during maintenance...are critical for performing ex- periments under high gas flux conditions. In addition, the pumping speed can be varied by reducing the rotation speed of

  2. Ultrahigh Vacuum Studies of the Fundamental Interactions of Chemical Warfare Agents and Their Simulants with Amorphous Silica

    Science.gov (United States)

    2015-07-14

    realize and my success in graduate school began with their mentorship. Erin Davis, Jessica Lu, Will Alexander, Steve Burrows , Alec Wagner, Yafen...description of the doser can be found in Larry Fiegland’s dissertation.68 The second doser is a variable sapphire-plate precision leak valve (Duniway

  3. Construction of MoS2/Si nanowire array heterojunction for ultrahigh-sensitivity gas sensor

    Science.gov (United States)

    Wu, Di; Lou, Zhenhua; Wang, Yuange; Xu, Tingting; Shi, Zhifeng; Xu, Junmin; Tian, Yongtao; Li, Xinjian

    2017-10-01

    Few-layer MoS2 thin films were synthesized by a two-step thermal decomposition process. In addition, MoS2/Si nanowire array (SiNWA) heterojunctions exhibiting excellent gas sensing properties were constructed and investigated. Further analysis reveals that such MoS2/SiNWA heterojunction devices are highly sensitive to nitric oxide (NO) gas under reverse voltages at room temperature (RT). The gas sensor demonstrated a minimum detection limit of 10 ppb, which represents the lowest value obtained for MoS2-based sensors, as well as an ultrahigh response of 3518% (50 ppm NO, ˜50% RH), with good repeatability and selectivity of the MoS2/SiNWA heterojunction. The sensing mechanisms were also discussed. The performance of the MoS2/SiNWA heterojunction gas sensors is superior to previous results, revealing that they have great potential in applications relating to highly sensitive gas sensors.

  4. Vacuum state supersymmetry in d=11 supergravity

    International Nuclear Information System (INIS)

    Vasilevich, D.V.

    1987-01-01

    Supersymmetry of vacuum state in d=11 supergravity is considered. Proceeding on sufficiently general assumptions relatively superformation parameter only Freud-Rubin type solutions may possess supersymmetries. To obtain this result no restrictions on the form of superformation parameter, supealgebra of vacuum global supersymmetry and the form of boson fields were imposed

  5. VACUUM ASSISTED CLOSURE IN DIABETIC FOOT MANAGEMENT

    OpenAIRE

    Moganakannan; `Prema; Arun Sundara Rajan

    2014-01-01

    Comparision of vacuum assisted closure vs conventional dressing in management of diabetic foot patients. 30 patients were taken in that 15 underwent vacuum therapy and remaining 15 underwent conventional dressing.They were analysed by the development of granulation tissue and wound healing.The study showed Vac therapy is the best modality for management of diabetic foot patients.

  6. AA, vacuum tank for stochastic precooling

    CERN Multimedia

    CERN PhotoLab

    1979-01-01

    The vaccum tank in which the fast stochastic precooling kicker was installed. It is clad with heating jackets for bake-out to 200 deg C, indispensable for reaching the operational vacuum of 7E-11 Torr. Alain Poncet, responsible for AA vacuum, is looking on. See also 7910268, 8002234.

  7. Quality Management of CERN Vacuum Controls

    CERN Document Server

    Antoniotti, F; Fortescue-Beck, E; Gama, J; Gomes, P; Le Roux, P; Pereira, H F; Pigny, G

    2014-01-01

    The vacuum controls Section (TE-VSC-ICM) is in charge of the monitoring, maintenance and consolidation of the control systems of all accelerators and detectors in CERN; this represents 6 000 instruments distributed along 128 km of vacuum chambers, often of heterogeneous architectures and of diverse

  8. Silicates materials of high vacuum technology

    CERN Document Server

    Espe, Werner

    2013-01-01

    Materials of High Vacuum Technology, Volume 2: Silicates covers silicate insulators of special importance to vacuum technology. The book discusses the manufacture, composition, and physical and chemical properties of technical glasses, quartz glass, quartzware, vycor glass, ceramic materials, mica, and asbestos.

  9. The probability of the false vacuum decay

    International Nuclear Information System (INIS)

    Kiselev, V.; Selivanov, K.

    1983-01-01

    The closed expession for the probability of the false vacuum decay in (1+1) dimensions is given. The probability of false vacuum decay is expessed as the product of exponential quasiclassical factor and a functional determinant of the given form. The method for calcutation of this determinant is developed and a complete answer for (1+1) dimensions is given

  10. The vacuum system for technological unit development and design

    Science.gov (United States)

    Zhukeshov, A. M.; Gabdullina, A. T.; Amrenova, A. U.; Giniyatova, Sh G.; Kaibar, A.; Sundetov, A.; Fermakhan, K.

    2015-11-01

    The paper shows results of development of plasma technological unit on the basis of accelerator of vacuum arc and automated system. During the previous years, the authors investigated the operation of pulsed plasma accelerator and developed unique technologies for hardening of materials. Principles of plasma formation in pulsed plasma accelerator were put into basis of the developed unit. Operation of the pulsed arc accelerator was investigated at different parameters of the charge. The developed vacuum system is designed for production of hi-tech plasma units in high technologies in fields of nanomaterials, mechanical and power engineering and production with high added value. Unlike integrated solutions, the system is a module one to allow its low cost, high reliability and simple maintenance. The problems of use of robots are discussed to modernize the technological process.

  11. The vacuum system for technological unit development and design

    International Nuclear Information System (INIS)

    Zhukeshov, A M; Gabdullina, A T; Amrenova, A U; Giniyatova, Sh G; Kaibar, A; Sundetov, A; Fermakhan, K

    2015-01-01

    The paper shows results of development of plasma technological unit on the basis of accelerator of vacuum arc and automated system. During the previous years, the authors investigated the operation of pulsed plasma accelerator and developed unique technologies for hardening of materials. Principles of plasma formation in pulsed plasma accelerator were put into basis of the developed unit. Operation of the pulsed arc accelerator was investigated at different parameters of the charge. The developed vacuum system is designed for production of hi-tech plasma units in high technologies in fields of nanomaterials, mechanical and power engineering and production with high added value. Unlike integrated solutions, the system is a module one to allow its low cost, high reliability and simple maintenance. The problems of use of robots are discussed to modernize the technological process. (paper)

  12. AMANDA Observations Constrain the Ultrahigh Energy Neutrino Flux

    Energy Technology Data Exchange (ETDEWEB)

    Halzen, Francis; /Wisconsin U., Madison; Hooper, Dan; /Fermilab

    2006-05-01

    A number of experimental techniques are currently being deployed in an effort to make the first detection of ultra-high energy cosmic neutrinos. To accomplish this goal, techniques using radio and acoustic detectors are being developed, which are optimally designed for studying neutrinos with energies in the PeV-EeV range and above. Data from the AMANDA experiment, in contrast, has been used to place limits on the cosmic neutrino flux at less extreme energies (up to {approx}10 PeV). In this letter, we show that by adopting a different analysis strategy, optimized for much higher energy neutrinos, the same AMANDA data can be used to place a limit competitive with radio techniques at EeV energies. We also discuss the sensitivity of the IceCube experiment, in various stages of deployment, to ultra-high energy neutrinos.

  13. Bridging ultrahigh-Q devices and photonic circuits

    Science.gov (United States)

    Yang, Ki Youl; Oh, Dong Yoon; Lee, Seung Hoon; Yang, Qi-Fan; Yi, Xu; Shen, Boqiang; Wang, Heming; Vahala, Kerry

    2018-05-01

    Optical microresonators are essential to a broad range of technologies and scientific disciplines. However, many of their applications rely on discrete devices to attain challenging combinations of ultra-low-loss performance (ultrahigh Q) and resonator design requirements. This prevents access to scalable fabrication methods for photonic integration and lithographic feature control. Indeed, finding a microfabrication bridge that connects ultrahigh-Q device functions with photonic circuits is a priority of the microcavity field. Here, an integrated resonator having a record Q factor over 200 million is presented. Its ultra-low-loss and flexible cavity design brings performance to integrated systems that has been the exclusive domain of discrete silica and crystalline microcavity devices. Two distinctly different devices are demonstrated: soliton sources with electronic repetition rates and high-coherence/low-threshold Brillouin lasers. This multi-device capability and performance from a single integrated cavity platform represents a critical advance for future photonic circuits and systems.

  14. A new vacuum for loop quantum gravity

    International Nuclear Information System (INIS)

    Dittrich, Bianca; Geiller, Marc

    2015-01-01

    We construct a new vacuum and representation for loop quantum gravity. Because the new vacuum is based on BF theory, it is physical for (2+1)-dimensional gravity, and much closer to the spirit of spin foam quantization in general. To construct this new vacuum and the associated representation of quantum observables, we introduce a modified holonomy–flux algebra that is cylindrically consistent with respect to the notion of refinement by time evolution suggested in Dittrich and Steinhaus (2013 arXiv:1311.7565). This supports the proposal for a construction of the physical vacuum made in Dittrich and Steinhaus (2013 arXiv:1311.7565) and Dittrich (2012 New J. Phys. 14 123004), and for (3+1)-dimensional gravity. We expect that the vacuum introduced here will facilitate the extraction of large scale physics and cosmological predictions from loop quantum gravity. (fast track communication)

  15. Vacuum and ultravacuum physics and technology

    CERN Document Server

    Bello, Igor

    2018-01-01

    Vacuum technology has enormous impact on human life in many aspects and fields, such as metallurgy, material development and production, food and electronic industry, microelectronics, device fabrication, physics, materials science, space science, engineering, chemistry, technology of low temperature, pharmaceutical industry, and biology. All decorative coatings used in jewelries and various daily products—including shiny decorative papers, the surface finish of watches, and light fixtures—are made using vacuum technological processes. Vacuum analytical techniques and vacuum technologies are pillars of the technological processes, material synthesis, deposition, and material analyses—all of which are used in the development of novel materials, increasing the value of industrial products, controlling the technological processes, and ensuring the high product quality. Based on physical models and calculated examples, the book provides a deeper look inside the vacuum physics and technology.

  16. [Ambulant treatment of wounds by vacuum sealing].

    Science.gov (United States)

    Ziegler, U E; Schmidt, K; Breithaupt, B; Menig, R; Debus, E S; Thiede, A

    2000-01-01

    The treatment of chronic wounds by vacuum sealing as an outpatient procedure is a new method of wound conditioning before closing the defect. The quality of life for the patient in his usual surrounding is maintained. Financial aspects also play a role in this treatment since costs for the health care system can be reduced. Various vacuum pumps, drainages and polymere foams are available and suitable for the outpatient treatment. The most important condition is to regularly check the vacuum. This can performed by the patient, the relatives or nursing staff. The main complication consists in loss of vacuum but technical and local or systemic complications can also appear. Individually applied vacuum dressings (polyvinyl foam, drainage tube and polymere foil) are practical. The ideal pump systems for the outpatient treatment are still not trial.

  17. Maxwell electrodynamics subjected to quantum vacuum fluctuations

    International Nuclear Information System (INIS)

    Gevorkyan, A. S.; Gevorkyan, A. A.

    2011-01-01

    The propagation of electromagnetic waves in the vacuum is considered taking into account quantum fluctuations in the limits of Maxwell-Langevin (ML) equations. For a model of “white noise” fluctuations, using ML equations, a second order partial differential equation is found which describes the quantum distribution of virtual particles in vacuum. It is proved that in order to satisfy observed facts, the Lamb Shift etc, the virtual particles should be quantized in unperturbed vacuum. It is shown that the quantized virtual particles in toto (approximately 86 percent) are condensed on the “ground state” energy level. It is proved that the extension of Maxwell electrodynamics with inclusion of the vacuum quantum field fluctuations may be constructed on a 6D space-time continuum with a 2D compactified subspace. Their influence on the refraction indexes of vacuum is studied.

  18. Mechanics and Physics of Precise Vacuum Mechanisms

    CERN Document Server

    Deulin, E. A; Panfilov, Yu V; Nevshupa, R. A

    2010-01-01

    In this book the Russian expertise in the field of the design of precise vacuum mechanics is summarized. A wide range of physical applications of mechanism design in electronic, optical-electronic, chemical, and aerospace industries is presented in a comprehensible way. Topics treated include the method of microparticles flow regulation and its determination in vacuum equipment and mechanisms of electronics; precise mechanisms of nanoscale precision based on magnetic and electric rheology; precise harmonic rotary and not-coaxial nut-screw linear motion vacuum feedthroughs with technical parameters considered the best in the world; elastically deformed vacuum motion feedthroughs without friction couples usage; the computer system of vacuum mechanisms failure predicting. This English edition incorporates a number of features which should improve its usefulness as a textbook without changing the basic organization or the general philosophy of presentation of the subject matter of the original Russian work. Exper...

  19. Modified heat treatment for lower temperature improvement of the mechanical properties of two ultrahigh strength low alloy steels

    Science.gov (United States)

    Tomita, Yoshiyuki; Okabayashi, Kunio

    1985-01-01

    In the previous papers, a new heat treatment for improving the lower temperature mechanical propertise of the ultrahigh strength low alloy steels was suggested by the authors which produces a mixed structure of 25 vol pct lower bainite and 75 vol pct martensite through isothermal transformation at 593 K for a short time followed by water quenching (after austenitization at 1133 K). In this paper, two commercial Japanese ultrahigh strength steels, 0.40 pct C-Ni-Cr-Mo (AISI 4340 type) and 0.40 pct C-Cr-Mo (AISI 4140 type), have been studied to determine the effect of the modified heat treatment, coupled above new heat treatment with γ ⇆ α' repctitive heat treatment, on the mechanical properties from ambient temperature (287 K) to 123 K. The results obtained for various test temperatures have been compared with those for the new heat treatment reported previously and the conventional 1133 K direct water quenching treatment. The incorporation of intermediate four cyclic γ ⇆ α' repctitive heat treatment steps (after the initial austenitization at 1133 K and oil quenching) into the new heat treatment reported previously, as compared with the conventional 1133 K direct water quenching treatment, significantly improved 0.2 pct proof stress as well as notch toughness of the 0.40 pct C-Ni-Cr-Mo ultrahigh strength steel at similar fracture ductility levels from 287 to 123 K. Also, this heat treatment, as compared with the conventional 1133 K direct water quenching treatment, significantly improved both 0.2 pct proof stress and notch toughness of the 0.40 pct C-Cr-Mo ultrahigh strength steel with increased fracture ductility at 203 K and above. The microstructure consists of mixed areas of ultrafine grained martensite, within which is the refined blocky, highly dislocated structure, and the second phase lower bainite (about 15 vol pct), which appears in acicular form and partitions prior austenite grains. This newly developed heat treatment makes it possible to modify

  20. Approximated calculation of the vacuum wave function and vacuum energy of the LGT with RPA method

    International Nuclear Information System (INIS)

    Hui Ping

    2004-01-01

    The coupled cluster method is improved with the random phase approximation (RPA) to calculate vacuum wave function and vacuum energy of 2 + 1 - D SU(2) lattice gauge theory. In this calculating, the trial wave function composes of single-hollow graphs. The calculated results of vacuum wave functions show very good scaling behaviors at weak coupling region l/g 2 >1.2 from the third order to the sixth order, and the vacuum energy obtained with RPA method is lower than the vacuum energy obtained without RPA method, which means that this method is a more efficient one

  1. Tomography system having an ultrahigh speed processing unit

    International Nuclear Information System (INIS)

    Cox, J.P. Jr.; Gerth, V.W. Jr.

    1977-01-01

    A transverse section tomography system has an ultrahigh-speed data processing unit for performing back projection and updating. An x-ray scanner directs x-ray beams through a planar section of a subject from a sequence of orientations and positions. The scanner includes a movably supported radiation detector for detecting the intensity of the beams of radiation after they pass through the subject

  2. Ultra-high energy cosmic rays: Setting the stage

    Science.gov (United States)

    Sokolsky, P.

    2013-06-01

    The history of ultra-high energy cosmic ray physics is reviewed from the post-war era of arrays such as Volcano Ranch, Haverah Park and Akeno to the development of air-fluorescence and current hybrid arrays. The aim of this paper is to present the background information needed for a better understanding of the current issues in this field that are discussed in much greater depth in the rest of this conference.

  3. Ultra-high energy cosmic rays: Setting the stage

    Directory of Open Access Journals (Sweden)

    Sokolsky P.

    2013-06-01

    Full Text Available The history of ultra-high energy cosmic ray physics is reviewed from the post-war era of arrays such as Volcano Ranch, Haverah Park and Akeno to the development of air-fluorescence and current hybrid arrays. The aim of this paper is to present the background information needed for a better understanding of the current issues in this field that are discussed in much greater depth in the rest of this conference.

  4. Proton-proton elastic scattering at ultrahigh energies

    International Nuclear Information System (INIS)

    Saleem, M.; Shaukat, M.A.; Fazal-e-Aleem

    1981-01-01

    Recent experimental results on proton-proton elastic scattering at high energies are discussed in the context of the comments by Chou and Yang. There does not appear to be any tendency that the experimental results would agree with the predictions of the geometrical model even at ultrahigh energies. The angular distribution structure as described by using the dipole pomeron is consistent with the experimental data at presently available high energies and predicts results quite different from the geometrical model. (author)

  5. Proton-proton elastic scattering at ultrahigh energies

    Energy Technology Data Exchange (ETDEWEB)

    Saleem, M.; Shaukat, M.A.; Fazal-e-Aleem (University of the Punjab, Lahore (Pakistan). Dept. of Physics)

    1981-05-30

    Recent experimental results on proton-proton elastic scattering at high energies are discussed in the context of the comments by Chou and Yang. There does not appear to be any tendency that the experimental results would agree with the predictions of the geometrical model even at ultrahigh energies. The angular distribution structure as described by using the dipole pomeron is consistent with the experimental data at presently available high energies and predicts results quite different from the geometrical model.

  6. ULTRAHIGH ENERGY COSMIC RAYS: REVIEW OF THE CURRENT SITUATION

    Directory of Open Access Journals (Sweden)

    Todor Stanev

    2013-12-01

    Full Text Available We describe the current situation of the data on the highest energy particles in the Universe – the ultrahigh energy cosmic rays. The new results in the field come from the Telescope Array experiment in Utah, U.S.A. For this reason we concentrate on the results from these experiments and compare them to the measurements of the other two recent experiments, the High Resolution Fly’sEye and the Southern Auger Observatory.

  7. Ultra-high Performance Liquid Chromatography in Steroid Analysis

    OpenAIRE

    Salonen, Fanny

    2017-01-01

    The latest version of liquid chromatography is ultra-high performance (or pressure) chromatography (UHPLC). In the technique, short and narrow-bore columns with particle sizes below 3 µm are used. The extremely high pressure used results in very short analysis times, excellent separation, and good resolution. This makes UHPLC a good choice for steroidal analysis. Steroids are a highly interesting area of study; they can be recognized as biomarkers for several diseases and are a relevant topic...

  8. Influence of Gap Distance on Vacuum Arc Characteristics of Cup Type AMF Electrode in Vacuum Interrupters

    International Nuclear Information System (INIS)

    Cheng Shaoyong; Xiu Shixin; Wang Jimei; Shen Zhengchao

    2006-01-01

    The greenhouse effect of SF 6 is a great concern today. The development of high voltage vacuum circuit breakers becomes more important. The vacuum circuit breaker has minimum pollution to the environment. The vacuum interrupter is the key part of a vacuum circuit breaker. The interrupting characteristics in vacuum and arc-controlling technique are the main problems to be solved for a longer gap distance in developing high voltage vacuum interrupters. To understand the vacuum arc characteristics and provide effective technique to control vacuum arc in a long gap distance, the arc mode transition of a cup-type axial magnetic field electrode is observed by a high-speed charge coupled device (CCD) video camera under different gap distances while the arc voltage and arc current are recorded. The controlling ability of the axial magnetic field on vacuum arc obviously decreases when the gap distance is longer than 40 mm. The noise components and mean value of the arc voltage significantly increase. The effective method for controlling the vacuum arc characteristics is provided by long gap distances based on the test results. The test results can be used as a reference to develop high voltage and large capacity vacuum interrupters

  9. Electroweak vacuum instability and renormalized Higgs field vacuum fluctuations in the inflationary universe

    Energy Technology Data Exchange (ETDEWEB)

    Kohri, Kazunori [Institute of Particle and Nuclear Studies, KEK, 1-1 Oho, Tsukuba 305-0801 (Japan); Matsui, Hiroki, E-mail: kohri@post.kek.jp, E-mail: matshiro@post.kek.jp [The Graduate University for Advanced Studies (SOKENDAI), 1-1 Oho, Tsukuba 305-0801 (Japan)

    2017-08-01

    In this work, we investigated the electroweak vacuum instability during or after inflation. In the inflationary Universe, i.e., de Sitter space, the vacuum field fluctuations < δ φ {sup 2} > enlarge in proportion to the Hubble scale H {sup 2}. Therefore, the large inflationary vacuum fluctuations of the Higgs field < δ φ {sup 2} > are potentially catastrophic to trigger the vacuum transition to the negative-energy Planck-scale vacuum state and cause an immediate collapse of the Universe. However, the vacuum field fluctuations < δ φ {sup 2} >, i.e., the vacuum expectation values have an ultraviolet divergence, and therefore a renormalization is necessary to estimate the physical effects of the vacuum transition. Thus, in this paper, we revisit the electroweak vacuum instability from the perspective of quantum field theory (QFT) in curved space-time, and discuss the dynamical behavior of the homogeneous Higgs field φ determined by the effective potential V {sub eff}( φ ) in curved space-time and the renormalized vacuum fluctuations < δ φ {sup 2} >{sub ren} via adiabatic regularization and point-splitting regularization. We simply suppose that the Higgs field only couples the gravity via the non-minimal Higgs-gravity coupling ξ(μ). In this scenario, the electroweak vacuum stability is inevitably threatened by the dynamical behavior of the homogeneous Higgs field φ, or the formations of AdS domains or bubbles unless the Hubble scale is small enough H < Λ {sub I} .

  10. Ultrahigh-energy cosmic rays: facts, myths and legends

    International Nuclear Information System (INIS)

    Anchordoqui, L.A.

    2011-01-01

    This is a written version of a series of lectures aimed at graduate students in astrophysics and theoretical/experimental particle physics. In the first part, we explain the important progress made in recent years towards understanding the experimental data on cosmic rays with energies > or approx. 10 8 GeV. We begin with a brief survey of the available data, including a description of the energy spectrum, mass composition and arrival directions. At this point we also give a short overview of experimental techniques. After that, we introduce the fundamentals of acceleration and propagation in order to discuss the conjectured nearby cosmic-ray sources, and emphasize some of the prospects for a new (multiparticle) astronomy. Next, we survey the state of the art regarding the ultrahigh-energy cosmic neutrinos that should be produced in association with the observed cosmic rays. In the second part, we summarize the phenomenology of cosmic-ray air showers. We explain the hadronic interaction models used to extrapolate results from collider data to ultrahigh energies, and describe the prospects for insights into forward physics at the Large Hadron Collider. We also explain the main electromagnetic processes that govern the longitudinal shower evolution. Armed with these two principal shower ingredients and motivation from the underlying physics, we describe the different methods proposed to distinguish primary species. In the last part, we outline how ultrahigh-energy cosmic-ray interactions can be used to probe new physics beyond the electroweak scale. (author)

  11. Ultra high vacuum systems for accelerators

    International Nuclear Information System (INIS)

    Loefgren, P.

    2001-01-01

    Full text: In order to perform controlled, stable, and reproducible experiments, several research areas today require very low pressures. Maybe the most important example is the research that is performed in storage rings and accelerators where the lifetime and stability of particle beams depends critically on the vacuum conditions. Although the vacuum requirements ultimately depend on the kind of experiments that is performed, the studies of more and more rare and exotic species in storage rings and accelerators today pushes the demands on the vacuum conditions towards lower and lower pressures. The final pressure obtained in the vacuum system can often be the key factor for the outcome of an experiment. Pioneering work in vacuum technology has therefore often been performed at storage rings and accelerator facilities around the world. In order to reach pressures in the low UHV regime and lower (below 10 -11 mbar), several aspects have to be considered which implies choosing the proper materials, pumps and vacuum gauges. In the absence of gases inleaking from the outside, the rate of gas entering a vacuum system is determined by the release of molecules adsorbed on the surfaces and the outgassing from the bulk of the vacuum chamber walls. This means that the choice of material and, equally important, the pre treatment of the material, must be such that these rates are minimised. Today the most widely used material for vacuum applications are stainless steel. Besides its many mechanical advantages, it is resistant to corrosion and oxidation. If treated correctly the major gas source in a stainless steel chamber is hydrogen outgassing from the chamber walls. The hydrogen outgassing can be decreased by vacuum firing at 950 deg. C under vacuum. In addition to choosing the right materials the choice of vacuum pumps is important for the final pressure. Since no vacuum pump is capable of taking care of all kinds of gases found in the rest gas at pressures below 10 -11

  12. Wireless Integrated Microelectronic Vacuum Sensor System

    Science.gov (United States)

    Krug, Eric; Philpot, Brian; Trott, Aaron; Lawrence, Shaun

    2013-01-01

    NASA Stennis Space Center's (SSC's) large rocket engine test facility requires the use of liquid propellants, including the use of cryogenic fluids like liquid hydrogen as fuel, and liquid oxygen as an oxidizer (gases which have been liquefied at very low temperatures). These fluids require special handling, storage, and transfer technology. The biggest problem associated with transferring cryogenic liquids is product loss due to heat transfer. Vacuum jacketed piping is specifically designed to maintain high thermal efficiency so that cryogenic liquids can be transferred with minimal heat transfer. A vacuum jacketed pipe is essentially two pipes in one. There is an inner carrier pipe, in which the cryogenic liquid is actually transferred, and an outer jacket pipe that supports and seals the vacuum insulation, forming the "vacuum jacket." The integrity of the vacuum jacketed transmission lines that transfer the cryogenic fluid from delivery barges to the test stand must be maintained prior to and during engine testing. To monitor the vacuum in these vacuum jacketed transmission lines, vacuum gauge readings are used. At SSC, vacuum gauge measurements are done on a manual rotation basis with two technicians, each using a handheld instrument. Manual collection of vacuum data is labor intensive and uses valuable personnel time. Additionally, there are times when personnel cannot collect the data in a timely fashion (i.e., when a leak is detected, measurements must be taken more often). Additionally, distribution of this data to all interested parties can be cumbersome. To simplify the vacuum-gauge data collection process, automate the data collection, and decrease the labor costs associated with acquiring these measurements, an automated system that monitors the existing gauges was developed by Invocon, Inc. For this project, Invocon developed a Wireless Integrated Microelectronic Vacuum Sensor System (WIMVSS) that provides the ability to gather vacuum

  13. Heat treatment for improvement in lower temperature mechanical properties of 0.40 pct C-Cr-Mo ultrahigh strength steel

    Science.gov (United States)

    Tomita, Yoshiyuki; Okabayashi, Kunio

    1983-11-01

    In the previous paper, it was reported that isothermal heat treatment of a commercial Japanese 0.40 pct C-Ni-Cr-Mo ultrahigh strength steel (AISI 4340 type) at 593 K for a short time followed by water quenching, in which a mixed structure of 25 vol pct lower bainite and 75 vol pct martensite is produced, results in the improvement of low temperature mechanical properties (287 to 123 K). The purpose of this paper is to study whether above new heat treatment will still be effective in commercial practice for improving low temperature mechanical properties of the ultrahigh strength steel when applied to a commercial Japanese 0.40 pct C-Cr-Mo ultrahigh strength steel which is economical because it lacks the expensive nickel component (AISI 4140 type). At and above 203 K this new heat treatment, as compared with the conventional 1133 K direct water quenching treatment, significantly improved the strength, tensile ductility, and notch toughness of the 0.40 pct C-Cr-Mo ultrahigh strength steel. At and above 203 K the new heat treatment also produced superior fracture ductility and notch toughness results at similar strength levels as compared to those obtained by using γ α' repetitive heat treatment for the same steel. However, the new heat treatment remarkably decreased fracture ductility and notch toughness of the 0.40 pct C-Cr-Mo ultrahigh strength steel below 203 K, and thus no significant improvement in the mechanical properties was noticeable as compared with the properties produced by the conventional 1133 K direct water quenching treatment and the γ α' repetitive heat treatment. This contrasts with the fact that the new heat treatment, as compared with the conventional 1133 K direct water quenching treatment and the γ α' repetitive heat treatment, dramatically improved the notch toughness of the 0.40 pct C-Ni-Cr-Mo ultrahigh strength steel, providing a better combination of strength and ductility throughout the 287 to 123 K temperature range. The difference

  14. Vacuum-bag-only processing of composites

    Science.gov (United States)

    Thomas, Shad

    Ultrasonic imaging in the C-scan mode in conjunction with the amplitude of the reflected signal was used to measure flow rates of an epoxy resin film penetrating through the thickness of single layers of woven carbon fabric. Assemblies, comprised of a single layer of fabric and film, were vacuum-bagged and ultrasonically scanned in a water tank during impregnation at 50°C, 60°C, 70°C, and 80°C. Measured flow rates were plotted versus inverse viscosity to determine the permeability in the thin film, non-saturated system. The results demonstrated that ultrasonic imaging in the C-scan mode is an effective method of measuring z-direction resin flow through a single layer of fabric. The permeability values determined in this work were consistent with permeability values reported in the literature. Capillary flow was not observed at the temperatures and times required for pressurized flow to occur. The flow rate at 65°C was predicted from the linear plot of flow rate versus inverse viscosity. The effects of fabric architecture on through-thickness flow rates during impregnation of an epoxy resin film were measured by ultrasonic imaging. Multilayered laminates comprised of woven carbon fabrics and epoxy films (prepregs) were fabricated by vacuum-bagging. Ultrasonic imaging was performed in a heated water tank (65°C) during impregnation. Impregnation rates showed a strong dependence on fabric architecture, despite similar areal densities. Impregnation rates are directly affected by inter-tow spacing and tow nesting, which depend on fabric architecture, and are indirectly affected by areal densities. A new method of predicting resin infusion rates in prepreg and resin film infusion processes was proposed. The Stokes equation was used to derive an equation to predict the impregnation rate of laminates as a function of fabric architecture. Flow rate data previously measured by ultrasound was analyzed with the new equation and the Kozeny-Carman equation. A fiber

  15. Vacuum-Ultraviolet Photovoltaic Detector.

    Science.gov (United States)

    Zheng, Wei; Lin, Richeng; Ran, Junxue; Zhang, Zhaojun; Ji, Xu; Huang, Feng

    2018-01-23

    Over the past two decades, solar- and astrophysicists and material scientists have been researching and developing new-generation semiconductor-based vacuum ultraviolet (VUV) detectors with low power consumption and small size for replacing traditional heavy and high-energy-consuming microchannel-detection systems, to study the formation and evolution of stars. However, the most desirable semiconductor-based VUV photovoltaic detector capable of achieving zero power consumption has not yet been achieved. With high-crystallinity multistep epitaxial grown AlN as a VUV-absorbing layer for photogenerated carriers and p-type graphene (with unexpected VUV transmittance >96%) as a transparent electrode to collect excited holes, we constructed a heterojunction device with photovoltaic detection for VUV light. The device exhibits an encouraging VUV photoresponse, high external quantum efficiency (EQE) and extremely fast tempera response (80 ns, 10 4 -10 6 times faster than that of the currently reported VUV photoconductive devices). This work has provided an idea for developing zero power consumption and integrated VUV photovoltaic detectors with ultrafast and high-sensitivity VUV detection capability, which not only allows future spacecraft to operate with longer service time and lower launching cost but also ensures an ultrafast evolution of interstellar objects.

  16. Vacuum control system of VEC

    International Nuclear Information System (INIS)

    Roy, Anindya; Bhole, R.B.; Bandopadhyay, D.L.; Mukhopadhyay, B.; Pal, Sarbajit; Sarkar, D.

    2009-01-01

    As a part of modernization of VEC (Variable Energy Cyclotron), the Vacuum Control System is being upgraded to PLC based automated system from initial Relay based Manual system. EPICS (Experimental Physics and Industrial Control System), a standard open source software tool for designing distributed control system, is chosen for developing the supervisory control software layer, leading towards a unified distributed control architecture of VEC Control System. A Modbus - TCP based IOC (I/O Controller) has been developed to communicate control data to PLC using Ethernet-TCP LAN. Keeping in mind, the operators' familiarity with MS-Windows, a MS-Windows based operator interface is developed using VB6. It is also used to test and evaluate EPICS compatibility to MS Windows. Several MS Windows ActiveX components e.g. text display, image display, alarm window, set-point input etc. have been developed incorporating Channel Access library of EPICS. Use of such components ease the programming complexity and reduce developmental time of the operator interface. The system is in the final phase of commissioning. (author)

  17. Baking results of KSTAR vacuum vessel

    Energy Technology Data Exchange (ETDEWEB)

    Kim, S. T.; Kim, Y. J.; Kim, K. M.; Im, D. S.; Joung, N. Y.; Yang, H. L.; Kim, Y. S.; Kwon, M. [National Fusion Research Institute, Daejeon (Korea, Republic of)

    2009-05-15

    The Korea Superconducting Tokamak Advanced Research (KSTAR) is an advanced superconducting tokamak designed to establish a scientific and technological basis for an attractive fusion reactor. The fusion energy in the tokamak device is released through fusion reactions of light atoms such as deuterium or helium in hot plasma state, of which temperature reaches several hundreds of millions Celsius. The high temperature plasma is created in the vacuum vessel that provides ultra high vacuum status. Accordingly, it is most important for the vacuum condition to keep clean not only inner space but also surface of the vacuum vessel to make high quality plasma. There are two methods planned to clean the wall surface of the KSTAR vacuum vessel. One is surface baking and the other is glow discharge cleaning (GDC). To bake the vacuum vessel, De-Ionized (DI) water is heated to 130 .deg. C and circulated in the passage between double walls of the vacuum vessel (VV) in order to bake the surface. The GDC operation uses hydrogen and inert gas discharges. In this paper, general configuration and brief introduction of the baking result will be reported.

  18. Baking results of KSTAR vacuum vessel

    International Nuclear Information System (INIS)

    Kim, S. T.; Kim, Y. J.; Kim, K. M.; Im, D. S.; Joung, N. Y.; Yang, H. L.; Kim, Y. S.; Kwon, M.

    2009-01-01

    The Korea Superconducting Tokamak Advanced Research (KSTAR) is an advanced superconducting tokamak designed to establish a scientific and technological basis for an attractive fusion reactor. The fusion energy in the tokamak device is released through fusion reactions of light atoms such as deuterium or helium in hot plasma state, of which temperature reaches several hundreds of millions Celsius. The high temperature plasma is created in the vacuum vessel that provides ultra high vacuum status. Accordingly, it is most important for the vacuum condition to keep clean not only inner space but also surface of the vacuum vessel to make high quality plasma. There are two methods planned to clean the wall surface of the KSTAR vacuum vessel. One is surface baking and the other is glow discharge cleaning (GDC). To bake the vacuum vessel, De-Ionized (DI) water is heated to 130 .deg. C and circulated in the passage between double walls of the vacuum vessel (VV) in order to bake the surface. The GDC operation uses hydrogen and inert gas discharges. In this paper, general configuration and brief introduction of the baking result will be reported

  19. Quark and gluon condensate in vacuum

    International Nuclear Information System (INIS)

    Vajnshtejn, A.I.; Zakharov, V.I.; Shifman, M.A.

    1979-01-01

    The mechanism of quark confinement has been reviewed. The fact that coloured particles in a free state cannot be observed is connected with specific properties of vacuum in quantum chromodynamics. The basic hypothesis consists in the existence of vacuum fields, quark and gluon condensates, which affect the coloured objects. The vacuum transparent relative to noncharged ''white'' states serves as a source of the force acting upon the coloured particles. It has been a sucess to examine strictly the action of the vacuum fields on quarks when the distance between them is relatively small and the force of the vacuum fields on quarks is relatively small too. It is shown that the interaction with the vacuum fields manifests itself earlier than the forces connected with the gluon exchange do. It is assumed that the vacuum condensate of quarks and gluons and its relation to properties of resonances and to the bag model exist in reality. The dispersion sum rules are used for calculating masses and lepton widths of resonances

  20. Is the Free Vacuum Energy Infinite?

    International Nuclear Information System (INIS)

    Shirazi, S. M.; Razmi, H.

    2015-01-01

    Considering the fundamental cutoff applied by the uncertainty relations’ limit on virtual particles’ frequency in the quantum vacuum, it is shown that the vacuum energy density is proportional to the inverse of the fourth power of the dimensional distance of the space under consideration and thus the corresponding vacuum energy automatically regularized to zero value for an infinitely large free space. This can be used in regularizing a number of unwanted infinities that happen in the Casimir effect, the cosmological constant problem, and so on without using already known mathematical (not so reasonable) techniques and tricks

  1. Gases and vacua handbook of vacuum physics

    CERN Document Server

    Beck, A H

    2013-01-01

    Handbook of Vacuum Physics, Volume 1: Gases and Vacua presents three major topics, which are the fourth to sixth parts of this volume. These topics are the remarks on units of physical quantities; kinetic theory of gases and gaseous flow; and theory of vacuum diffusion pumps. The first topic aims to present concisely the significance of units of physical quantities, catering the need and interest of those who take measurements and make calculations in different fields of vacuum sciences. The technique and applications of this particular topic are also provided. The second main topic focuses sp

  2. Plasma instability of a vacuum arc centrifuge

    International Nuclear Information System (INIS)

    Hole, M.J.; Dallaqua, R.S.; Simpson, S.W.; Del Bosco, E.

    2002-01-01

    Ever since conception of the vacuum arc centrifuge in 1980, periodic fluctuations in the ion saturation current and floating potential have been observed in Langmuir probe measurements in the rotation region of a vacuum arc centrifuge. In this work we develop a linearized theoretical model to describe a range of instabilities in the vacuum arc centrifuge plasma column, and then test the validity of the description through comparison with experiment. We conclude that the observed instability is a 'universal' instability, driven by the density gradient, in a plasma with finite conductivity

  3. Cold vacuum drying facility site evaluation report

    International Nuclear Information System (INIS)

    Diebel, J.A.

    1996-01-01

    In order to transport Multi-Canister Overpacks to the Canister Storage Building they must first undergo the Cold Vacuum Drying process. This puts the design, construction and start-up of the Cold Vacuum Drying facility on the critical path of the K Basin fuel removal schedule. This schedule is driven by a Tri-Party Agreement (TPA) milestone requiring all of the spent nuclear fuel to be removed from the K Basins by December, 1999. This site evaluation is an integral part of the Cold Vacuum Drying design process and must be completed expeditiously in order to stay on track for meeting the milestone

  4. Report of the Synchrotron Radiation Vacuum Workshop

    International Nuclear Information System (INIS)

    Avery, R.T.

    1984-06-01

    The Synchrotron Radiation Vacuum Workshop was held to consider two vacuum-related problems that bear on the design of storage rings and beam lines for synchrotron radiation facilities. These problems are gas desorption from the vacuum chamber walls and carbon deposition on optical components. Participants surveyed existing knowledge on these topics and recommended studies that should be performed as soon as possible to provide more definitive experimental data on these topics. This data will permit optimization of the final design of the Advanced Light Source (ALS) and its associated beam lines. It also should prove useful for other synchrotron radiation facilities as well

  5. Vacuum anti-shielding of monopoles

    International Nuclear Information System (INIS)

    Goebel, D.J.

    1984-01-01

    This chapter examines the difficulties in calculating the vacuum polarization, or magnetization, induced in the vacuum by a monopole. The usual Lagrangian formalism and consequent Feynman rules do not apply. Another problem is that the interaction strength between the monopole and a charge is not small (unless it vanishes exactly) because it is quantized to half integer values. Perturbation theory is therefore not applicable. The discussed problems are solved by using the old fashioned method of calculating a vacuum expectation value as a sum over single particle modes

  6. Quark virtuality and QCD vacuum condensates

    International Nuclear Information System (INIS)

    Zhou Lijuan; Ma Weixing

    2004-01-01

    Based on the Dyson-Schwinger equations (DSEs) in the 'rainbow' approximation, the authors investigate the quark virtuality in the vacuum state and quantum-chromodynamics (QCD) vacuum condensates. In particular, authors calculate the local quark vacuum condensate and quark-gluon mixed condensates, and then the virtuality of quark. The calculated quark virtualities are λ u,d 2 =0.7 GeV 2 for u, d quarks, and λ s 2 =1.6 GeV 2 for s quark. The theoretical predictions are consistent with empirical values used in QCD sum rules, and also fit to lattice QCD predictions

  7. Vacuum engineering, calculations, formulas, and solved exercises

    CERN Document Server

    Berman, Armand

    1992-01-01

    This book was written with two main objectives in mind-to summarize and organize the vast material of vacuum technology in sets of useful formulas, and to provide a collection of worked out exercises showing how to use these formulas for solving technological problems. It is an ideal reference source for those with little time to devote to a full mathematical treatment of the many problems issued in vacuum practice, but who have a working knowledge of the essentials of vacuum technology, elementary physics, and mathematics. This time saving book employs a problem-solving approach throughout, p

  8. The fine art of preparing a vacuum

    CERN Multimedia

    2006-01-01

    The vacuum chambers, or beam pipes, of the LHC experiments are located right at the interface between the detectors and the accelerator, and are therefore crucial to the LHC project as a whole. In this domain, the ALICE and CMS experiments have just passed an important milestone, with the completion of the first of CMS's two end-cap vacuum chambers, together with the completion and bakeout of an 18-metre section of the ALICE vacuum chamber. These complex projects, for which CERN's AT/VAC Group is responsible, involved dozens of people over a number of years.

  9. Some aspects of vacuum ultraviolet radiation physics

    CERN Document Server

    Damany, Nicole; Vodar, Boris

    2013-01-01

    Some Aspects of Vacuum Ultraviolet Radiation Physics presents some data on the state of research in vacuum ultraviolet radiation in association with areas of physics. Organized into four parts, this book begins by elucidating the optical properties of solids in the vacuum ultraviolet region (v.u.v.), particularly the specific methods of determination of optical constants in v.u.v., the properties of metals, and those of ionic insulators. Part II deals with molecular spectroscopy, with emphasis on the spectra of diatomic and simple polyatomic molecules, paraffins, and condensed phases. Part III

  10. An ultra-high-vacuum multiple grating chamber and scan drive with improved grating change

    International Nuclear Information System (INIS)

    Hulbert, S.L.; Holly, D.J.; Middleton, F.H.; Wallace, D.J.; Wisconsin Univ., Stoughton, WI; Wisconsin Univ., Stoughton, WI

    1989-01-01

    We describe a new grating chamber and scan drive which has been designed, built, and tested by Physical Sciences Laboratory of the University of Wisconsin for the new high flux, high-resolution spectroscopy branch line of the TOK hybrid wiggler/undulator on the NSLS VUV ring. The chamber will contain spherical gratings to be used in the Spherical Grating Monochromator (SGM) configuration introduced by Chen and Sette. The grating chamber houses five 180 mm x 35 mm x 30 mm gratings capable of scanning a range of 12 degree (-14 degree to +8 degree with respect to the incoming beam direction) for VUV and soft X-ray diffraction. The gratings can be switched and precisely indexed while under ultra-high vacuum (UHV) at any scan angle and are mechanically isolated from the vacuum chamber to prevent inaccuracies due to chamber distortions. The gratings can separately be adjusted for height, yaw, pitch, and roll, with the latter three performed while in vacuo. The scan drive provides a resolution of 0.03 arc sec with linearity over the 12 degree range of ∼1.5 arc sec and absolute reproducibility of 1 arc sec. 5 refs., 5 figs

  11. A method for the determination of low nitrogen concentrations in niobium by vacuum hot extraction

    International Nuclear Information System (INIS)

    Gruenwald, W.; Haessner, F.; Schulze, K.

    1976-01-01

    A method for the vacuum hot extraction of gases without the use of crucibles and fluxes is described and applied to the determination of gas contents of high-melting-point metals at low atomic ppm. The Nb-N system is quoted as an example. The reaction vessel (after baking at 150 0 C) was evacuated by means of a turbomolecular pump at an effective rate of 240 l s -1 . Degassing was carried out in ultra-high vacuum employing a residual nitrogen partial pressure of 2 X 10 -10 Torr and liquid and/or solid samples were melted by the levitation method in a radiofrequency field. The evolved gases were detected using a quadrupole mass filter and the quantity of nitrogen evolved calculated by integrating the partial pressure over the time period at a given pumping rate independent of pressure. In addition to giving a chemical analysis of the gas-metal system at low atomic ppm, this method also enables the thermodynamic and kinetic parameters to be determined. The minimum detectable concentration of nitrogen dissolved in niobium was ca. 0.5 at. ppm, the distribution coefficient between solid and liquid niobium 0.76 with the solubility of nitrogen being unaffected by additions of carbon up to 4.5 at.%. The contamination of high purity niobium during sample preparation has also been investigated. (Auth.)

  12. ITER vacuum vessel structural analysis completion during manufacturing phase

    Energy Technology Data Exchange (ETDEWEB)

    Martinez, J.-M., E-mail: jean-marc.martinez@live.fr [ITER Organization, Route Vinon sur Verdon, CS 90046, 13067, St. Paul lez Durance, Cedex (France); Alekseev, A.; Sborchia, C.; Choi, C.H.; Utin, Y.; Jun, C.H.; Terasawa, A.; Popova, E.; Xiang, B.; Sannazaro, G.; Lee, A.; Martin, A.; Teissier, P.; Sabourin, F. [ITER Organization, Route Vinon sur Verdon, CS 90046, 13067, St. Paul lez Durance, Cedex (France); Caixas, J.; Fernandez, E.; Zarzalejos, J.M. [F4E, c/Josep Pla, n.2, Torres Diagonal Litoral, Edificio B3, E-08019, Barcelona (Spain); Kim, H.-S.; Kim, Y.G. [ITER Korea, National Fusion Research Institute, Daejeon (Korea, Republic of); Privalova, E. [NTC “Sintez”, Efremov Inst., 189631 Metallostroy, St. Petersburg (Russian Federation); and others

    2016-11-01

    Highlights: • ITER Vacuum Vessel (VV) is a part of the first barrier to confine the plasma. • A Nuclear Pressure Equipment necessitates Agreed Notified Body to assure design, fabrication, and conformance testing and quality assurance. • Some supplementary RCC-MR margin targets have been considered to guarantee considerable structural margins in areas not inspected in operation. • Many manufacturing deviation requests (MDR) and project change requests (PCR) impose to re-evaluate the structural margin. • Several structural analyses were performed with global and local models to guarantee the structural integrity of the whole ITER Vacuum Vessel. - Abstract: Some years ago, analyses were performed by ITER Organization Central Team (IO-CT) to verify the structural integrity of the ITER vacuum vessel baseline design fixed in 2010 and classified as a Protection Important Component (PIC). The manufacturing phase leads the ITER Organization domestic agencies (IO-DA) and their contracted manufacturers to propose detailed design improvements to optimize the manufacturing or inspection process. These design and quality inspection changes can affect the structural margins with regards to the Codes&Standards and thus oblige to evaluate one more time the modified areas. This paper proposes an overview of the additional analyses already performed to guarantee the structural integrity of the manufacturing designs. In this way, CT and DAs have been strongly involved to keep the considerable margins obtained previously which were used to fix reasonable compensatory measures for the lack of In Service Inspections of a Nuclear Pressure Equipment (NPE).

  13. Chromium depletion from stainless steels during vacuum annealing

    International Nuclear Information System (INIS)

    Smith, A.F.; Hales, R.

    1977-01-01

    During selective chromium oxidation of stainless steels the changes in chromium concentration at the metal surface and in the metal have an important bearing on the overall oxidation performance. It has been proposed that an analogue of chromium behaviour during selective oxidation is obtained from volatilisation of chromium during high temperature vacuum annealing. In the present report the evaporation of chromium from 316 type of steel, vacuum annealed at 1,000 0 C, has been investigated by means of energy dispersive X-ray analysis and by neutron activation analysis. It was established that chromium loss from austenitic stainless steels is rate controlled by interdiffusion in the alloy. As predicted the chromium concentration at the metal surface decreased with increasing vacuum annealing time. The chromium depletion profile in the metal was in good agreement with the previously derived model apart from an anomalous region near the surface. Here the higher resolution of the neutron activation technique indicated a zone within approximately 2μm of the surface where the chromium concentration decreased more steeply than expected. (orig.) [de

  14. ITER vacuum vessel structural analysis completion during manufacturing phase

    International Nuclear Information System (INIS)

    Martinez, J.-M.; Alekseev, A.; Sborchia, C.; Choi, C.H.; Utin, Y.; Jun, C.H.; Terasawa, A.; Popova, E.; Xiang, B.; Sannazaro, G.; Lee, A.; Martin, A.; Teissier, P.; Sabourin, F.; Caixas, J.; Fernandez, E.; Zarzalejos, J.M.; Kim, H.-S.; Kim, Y.G.; Privalova, E.

    2016-01-01

    Highlights: • ITER Vacuum Vessel (VV) is a part of the first barrier to confine the plasma. • A Nuclear Pressure Equipment necessitates Agreed Notified Body to assure design, fabrication, and conformance testing and quality assurance. • Some supplementary RCC-MR margin targets have been considered to guarantee considerable structural margins in areas not inspected in operation. • Many manufacturing deviation requests (MDR) and project change requests (PCR) impose to re-evaluate the structural margin. • Several structural analyses were performed with global and local models to guarantee the structural integrity of the whole ITER Vacuum Vessel. - Abstract: Some years ago, analyses were performed by ITER Organization Central Team (IO-CT) to verify the structural integrity of the ITER vacuum vessel baseline design fixed in 2010 and classified as a Protection Important Component (PIC). The manufacturing phase leads the ITER Organization domestic agencies (IO-DA) and their contracted manufacturers to propose detailed design improvements to optimize the manufacturing or inspection process. These design and quality inspection changes can affect the structural margins with regards to the Codes&Standards and thus oblige to evaluate one more time the modified areas. This paper proposes an overview of the additional analyses already performed to guarantee the structural integrity of the manufacturing designs. In this way, CT and DAs have been strongly involved to keep the considerable margins obtained previously which were used to fix reasonable compensatory measures for the lack of In Service Inspections of a Nuclear Pressure Equipment (NPE).

  15. Development of an oxidized porous silicon vacuum microtriode

    Energy Technology Data Exchange (ETDEWEB)

    Smith, II, Don Deewayne [Texas A & M Univ., College Station, TX (United States)

    1994-05-01

    In order to realize a high-power microwave amplifier design known as a gigatron, a gated field emission array must be developed that can deliver a high-intensity electron beam at gigahertz frequencies. No existing field emission device meets the requirements for a gigatron cathode. In the present work, a porous silicon-based approach is evaluated. The use of porous silicon reduces the size of a single emitter to the nanometer scale, and a true two-dimensional array geometry can be approached. A wide number of applications for such a device exist in various disciplines. Oxidized porous silicon vacuum diodes were first developed in 1990. No systematic study had been done to characterize the performance of these devices as a function of the process parameters. The author has done the first such study, fabricating diodes from p<100>, p<111>, and n<100> silicon substrates. Anodization current densities from 11 mA/cm2 to 151 mA/cm2 were used, and Fowler-Nordheim behavior was observed in over 80% of the samples. In order to effectively adapt this technology to mainstream vacuum microelectronic applications, a means of creating a gated triodic structure must be found. No previous attempts had successfully yielded such a device. The author has succeeded in utilizing a novel metallization method to fabricate the first operational oxidized porous silicon vacuum microtriodes, and results are encouraging.

  16. An anisotropic universe due to dimension-changing vacuum decay

    International Nuclear Information System (INIS)

    Scargill, James H.C.

    2015-01-01

    In this paper we consider the question of observational signatures of a false vacuum decay event in the early universe followed by a period of inflation; in particular, motivated by the string landscape, we consider decays in which the parent vacuum has a smaller number of large dimensions than the current vacuum, which leads to an anisotropic universe. We go beyond previous studies, and examine the effects on the CMB temperature and polarisation power spectra, due to both scalar and tensor modes, and consider not only late-time effects but also the full cosmological perturbation theory at early times. We find that whilst the scalar mode behaves as one would expect, and the effects of anisotropy at early times are sub-dominant to the late-time effects already studied, for the tensor modes in fact the the early-time effects grow with multipole and can become much larger than one would expect, even dominating over the late-time effects. Thus these effects should be included if one is looking for such a signal in the tensor modes

  17. Is there vacuum when there is mass? Vacuum and non-vacuum solutions for massive gravity

    International Nuclear Information System (INIS)

    Martín-Moruno, Prado; Visser, Matt

    2013-01-01

    Massive gravity is a theory which has a tremendous amount of freedom to describe different cosmologies, but at the same time, the various solutions one encounters must fulfil some rather nontrivial constraints. Most of the freedom comes not from the Lagrangian, which contains only a small number of free parameters (typically three depending on counting conventions), but from the fact that one is in principle free to choose the reference metric almost arbitrarily—which effectively introduces a non-denumerable infinity of free parameters. In the current paper, we stress that although changing the reference metric would lead to a different cosmological model, this does not mean that the dynamics of the universe can be entirely divorced from its matter content. That is, while the choice of reference metric certainly influences the evolution of the physically observable foreground metric, the effect of matter cannot be neglected. Indeed the interplay between matter and geometry can be significantly changed in some specific models; effectively since the graviton would be able to curve the spacetime by itself, without the need of matter. Thus, even the set of vacuum solutions for massive gravity can have significant structure. In some cases, the effect of the reference metric could be so strong that no conceivable material content would be able to drastically affect the cosmological evolution. Dedicated to the memory of Professor Pedro F González–Díaz (paper)

  18. An Evaluation of Ultra-High Pressure Regulator for Robotic Lunar Landing Spacecraft

    Science.gov (United States)

    Burnside, Christopher; Trinh, Huu; Pedersen, Kevin

    2011-01-01

    The Robotic Lunar Lander Development (RLLD) Project Office at NASA Marshall Space Flight Center (MSFC) has studied several lunar surface science mission concepts. These missions focus on spacecraft carrying multiple science instruments and power systems that will allow extended operations on the lunar surface. Initial trade studies of launch vehicle options for these mission concepts indicate that the spacecraft design will be significantly mass-constrained. To minimize mass and facilitate efficient packaging, the notional propulsion system for these landers has a baseline of an ultra-high pressure (10,000 psig) helium pressurization system that has been used on Defense missiles. The qualified regulator is capable of short duration use; however, the hardware has not been previously tested at NASA spacecraft requirements with longer duration. Hence, technical risks exist in using this missile-based propulsion component for spacecraft applications. A 10,000-psig helium pressure regulator test activity is being carried out as part of risk reduction testing for MSFC RLLD project. The goal of the test activity is to assess the feasibility of commercial off-the-shelf ultra-high pressure regulator by testing with a representative flight mission profile. Slam-start, gas blowdown, water expulsion, lock-up, and leak tests are also performed on the regulator to assess performance under various operating conditions. The preliminary test results indicated that the regulator can regulate helium to a stable outlet pressure of 740 psig within the +/- 5% tolerance band and maintain a lock-up pressure less than +5% for all tests conducted. Numerous leak tests demonstrated leakage less than 10-3 standard cubic centimeters per second (SCCS) for internal seat leakage at lock-up and less than10-5 SCCS for external leakage through the regulator ambient reference cavity. The successful tests have shown the potential for 10,000 psig helium systems in NASA spacecraft and have reduced risk

  19. Analysis of Gas Membrane Ultra-High Purification of Small Quantities of Mono-Isotopic Silane

    Energy Technology Data Exchange (ETDEWEB)

    de Almeida, Valmor F [ORNL; Hart, Kevin J [ORNL

    2016-09-01

    A small quantity of high-value, crude, mono-isotopic silane is a prospective gas for a small-scale, high-recovery, ultra-high membrane purification process. This is an unusual application of gas membrane separation for which we provide a comprehensive analysis of a simple purification model. The goal is to develop direct analytic expressions for estimating the feasibility and efficiency of the method, and guide process design; this is only possible for binary mixtures of silane in the dilute limit which is a somewhat realistic case. Among the common impurities in crude silane, methane poses a special membrane separation challenge since it is chemically similar to silane. Other potential problematic surprises are: ethylene, diborane and ethane (in this order). Nevertheless, we demonstrate, theoretically, that a carefully designed membrane system may be able to purify mono-isotopic, crude silane to electronics-grade level in a reasonable amount of time and expenses. We advocate a combination of membrane materials that preferentially reject heavy impurities based on mobility selectivity, and light impurities based on solubility selectivity. We provide estimates for the purification of significant contaminants of interest. To improve the separation selectivity, it is advantageous to use a permeate chamber under vacuum, however this also requires greater control of in-leakage of impurities in the system. In this study, we suggest cellulose acetate and polydimethylsiloxane as examples of membrane materials on the basis of limited permeability data found in the open literature. We provide estimates on the membrane area needed and priming volume of the cell enclosure for fabrication purposes when using the suggested membrane materials. These estimates are largely theoretical in view of the absence of reliable experimental data for the permeability of silane. Last but not least, future extension of this work to the non-dilute limit may apply to the recovery of silane from

  20. High vacuum tribology of polycrystalline diamond coatings

    Indian Academy of Sciences (India)

    Polycrystalline diamond coatings; hot filament CVD; high vacuum tribology. 1. Introduction .... is a characteristic of graphite. We mark the (diamond ... coefficient of friction due to changes in substrate temperature. The average coefficient of.

  1. Gravitational collapse and the vacuum energy

    International Nuclear Information System (INIS)

    Campos, M

    2014-01-01

    To explain the accelerated expansion of the universe, models with interacting dark components (dark energy and dark matter) have been considered recently in the literature. Generally, the dark energy component is physically interpreted as the vacuum energy of the all fields that fill the universe. As the other side of the same coin, the influence of the vacuum energy on the gravitational collapse is of great interest. We study such collapse adopting different parameterizations for the evolution of the vacuum energy. We discuss the homogeneous collapsing star fluid, that interacts with a vacuum energy component, using the stiff matter case as example. We conclude this work with a discussion of the Cahill-McVittie mass for the collapsed object.

  2. Analytical and numerical tools for vacuum systems

    CERN Document Server

    Kersevan, R

    2007-01-01

    Modern particle accelerators have reached a level of sophistication which require a thorough analysis of all their sub-systems. Among the latter, the vacuum system is often a major contributor to the operating performance of a particle accelerator. The vacuum engineer has nowadays a large choice of computational schemes and tools for the correct analysis, design, and engineering of the vacuum system. This paper is a review of the different type of algorithms and methodologies which have been developed and employed in the field since the birth of vacuum technology. The different level of detail between simple back-of-the-envelope calculations and more complex numerical analysis is discussed by means of comparisons. The domain of applicability of each method is discussed, together with its pros and cons.

  3. Exact vacuum energy of orbifold lattice theories

    International Nuclear Information System (INIS)

    Matsuura, So

    2007-01-01

    We investigate the orbifold lattice theories constructed from supersymmetric Yang-Mills matrix theories (mother theories) with four and eight supercharges. We show that the vacuum energy of these theories does not receive any quantum correction perturbatively

  4. Design of the ZTH vacuum liner

    International Nuclear Information System (INIS)

    Prince, P.P.; Dike, R.S.

    1987-01-01

    The current status of the ZTh vacuum liner design is covered by this report. ZTH will be the first experiment to be installed in the CPRF (Confinement Physics Research Facility) at the Los Alamos National Laboratory and is scheduled to be operational at the rated current of 4 MA in 1992. The vacuum vessel has a 2.4m major radius and a 40 cm minor radius. Operating parameters which drive the vacuum vessel mechanical design include a 300 C bakeout temperature, an armour support system capable of withstanding 25 kV, a high toroidal resistance, 1250 kPa magnetic loading, a 10 minute cycle time, and high positional accuracy with respect to the conducting shell. The vacuum vessel design features which satisfy the operating parameters are defined

  5. Topology of classical vacuum space-time

    International Nuclear Information System (INIS)

    Cho, Y.M.

    2007-04-01

    We present a topological classification of classical vacuum space-time. Assuming the 3-dimensional space allows a global chart, we show that the static vacuum space-time of Einstein's theory can be classified by the knot topology π 3 (S 3 ) = π 3 (S 2 ). Viewing Einstein's theory as a gauge theory of Lorentz group and identifying the gravitational connection as the gauge potential of Lorentz group, we construct all possible vacuum gravitational connections which give a vanishing curvature tensor. With this we show that the vacuum connection has the knot topology, the same topology which describes the multiple vacua of SU(2) gauge theory. We discuss the physical implications of our result in quantum gravity. (author)

  6. 2XIIB vacuum vessel: a unique design

    International Nuclear Information System (INIS)

    Hibbs, S.M.; Calderon, M.O.

    1975-01-01

    The 2XIIB mirror confinement experiment makes unique demands on its vacuum system. The confinement coil set encloses a cavity whose surface is comprised of both simple and compound curves. Within this cavity and at the core of the machine is the operating vacuum which is on the order of 10 -9 Torr. The vacuum container fits inside the cavity, presenting an inside surface suitable for titanium getter pumping and a means of removing the heat load imposed by incandescent sublimator wires. In addition, the cavity is constructed of nonmagnetic and nonconducting materials (nonmetals) to avoid distortion of the pulsed confinement field. It is also isolated from mechanical shocks induced in the machine's main structure when the coils are pulsed. This paper describes the design, construction, and operation of the 2XIIB high-vacuum vessel that has been performing successfully since early 1974

  7. Production of Lunar Oxygen Through Vacuum Pyrolysis

    National Research Council Canada - National Science Library

    Matchett, John

    2006-01-01

    .... The vacuum pyrolysis method of oxygen production from lunar regolith presents a viable option for in situ propellant production because of its simple operation involving limited resources from earth...

  8. Design of the CLIC Quadrupole Vacuum Chambers

    CERN Document Server

    Garion, C

    2010-01-01

    The Compact Linear Collider, under study, requires vacuum chambers with a very small aperture, of the order of 8 mm in diameter, and with a length up to around 2 m for the main beam quadrupoles. To keep the very tight geometrical tolerances on the quadrupoles, no bake out is allowed. The main issue is to reach UHV conditions (typically 10-9 mbar static pressure) in a system where the vacuum performance is driven by water outgassing. For this application, a thinwalled stainless steel vacuum chamber with two ante chambers equipped with NEG strips, is proposed. The mechanical design, especially the stability analysis, is shown. The key technologies of the prototype fabrication are given. Vacuum tests are carried out on the prototypes. The test set-up as well as the pumping system conditions are presented.

  9. FRIB driver linac vacuum model and benchmarks

    CERN Document Server

    Durickovic, Bojan; Kersevan, Roberto; Machicoane, Guillaume

    2014-01-01

    The Facility for Rare Isotope Beams (FRIB) is a superconducting heavy-ion linear accelerator that is to produce rare isotopes far from stability for low energy nuclear science. In order to achieve this, its driver linac needs to achieve a very high beam current (up to 400 kW beam power), and this requirement makes vacuum levels of critical importance. Vacuum calculations have been carried out to verify that the vacuum system design meets the requirements. The modeling procedure was benchmarked by comparing models of an existing facility against measurements. In this paper, we present an overview of the methods used for FRIB vacuum calculations and simulation results for some interesting sections of the accelerator. (C) 2013 Elsevier Ltd. All rights reserved.

  10. Theorem on axially symmetric gravitational vacuum configurations

    Energy Technology Data Exchange (ETDEWEB)

    Papadopoulos, A; Le Denmat, G [Paris-6 Univ., 75 (France). Inst. Henri Poincare

    1977-01-24

    A theorem is proved which asserts the non-existence of axially symmetric gravitational vacuum configurations with non-stationary rotation only. The eventual consequences in black-hole physics are suggested.

  11. Re-circulating linac vacuum system

    International Nuclear Information System (INIS)

    Wells, Russell P.; Corlett, John N.; Zholents, Alexander A.

    2003-01-01

    The vacuum system for a proposed 2.5 GeV, 10ΜA recirculating linac synchrotron light source [1] is readily achievable with conventional vacuum hardware and established fabrication processes. Some of the difficult technical challenges associated with synchrotron light source storage rings are sidestepped by the relatively low beam current and short beam lifetime requirements of a re-circulating linac. This minimal lifetime requirement leads directly to relatively high limits on the background gas pressure through much of the facility. The 10ΜA average beam current produces very little synchrotron radiation induced gas desorption and thus the need for an ante-chamber in the vacuum chamber is eliminated. In the arc bend magnets, and the insertion devices, the vacuum chamber dimensions can be selected to balance the coherent synchrotron radiation and resistive wall wakefield effects, while maintaining the modest limits on the gas pressure and minimal outgassing

  12. High Vacuum Techniques for Anionic Polymerization

    KAUST Repository

    Ratkanthwar, Kedar; Hadjichristidis, Nikolaos; Mays, Jimmy

    2015-01-01

    Anionic polymerization high vacuum techniques (HVTs) are the most suitable for the preparation of polymer samples with well-defined complex macromolecular architectures. Though HVTs require glassblowing skill for designing and making polymerization

  13. Vacuum ultraviolet photochemistry of tetrahydrothiophene and sulfolane

    International Nuclear Information System (INIS)

    Scala, A.A.; Colon, I.

    1979-01-01

    The vacuum uv photolysis of tetrahydrothiophene (THT) involves the breaking of the S to α-C bond. Besides ethylene, C 3 H 6 and 1,3-butadiene are also formed. Photolyses of THT, tetrahydrofuran, and pyrrolidine are similar. The vacuum uv photolysis of tetramethylene sulfone (sulfolane) was also studied; products are SO 2 , cyclobutane, 1-butene, and ethylene. No cis-2-butene was observed

  14. Vacuum-plasma coverings on the aircraft

    International Nuclear Information System (INIS)

    Shvetsov, V.D.; Teksin, Eh.K.; Lysyak, A.A.

    1998-01-01

    In the article are considered the perspectives of vacuum-plasma coverings using for engine components protection. The influence of operating factors on the durability of components which has the vacuum-plasma coverings is show.Leads in using the concept of informational parameter of quality.The recommendation about organization of engine with abolished components maintenance by methods of flyable conditions or reliability level are given

  15. The Effect of Forcing on Vacuum Radiation

    OpenAIRE

    Jones-Smith, Katherine; Mathur, Harsh; Lowenstein, Ashton

    2018-01-01

    Vacuum radiation has been the subject of theoretical study in both cosmology and condensed matter physics for many decades. Recently there has been impressive progress in experimental realizations as well. Here we study vacuum radiation when a field mode is driven both parametrically and by a classical source. We find that in the Heisenberg picture the field operators of the mode undergo a Bogolyubov transformation combined with a displacement, in the Schr\\"odinger picture the oscillator evol...

  16. Cluster expansion for vacuum confining fields

    International Nuclear Information System (INIS)

    Simonov, Yu.A.

    1987-01-01

    Colored particle Green functions in vacuum background random fields are written as path integrals. Averaging over random fields is done using the cluster (cumulant) expansion. The existence of a finite correlation length for vacuum background fields is shown to produce the linear confinement, in agreement with the results, obtained with the help of averaged Hamiltonians. A modified form of cluster expansion for nonabelian fields is introduced using the path-ordered cumulants

  17. Vacuum decay in an interacting multiverse

    Science.gov (United States)

    Robles-Pérez, S.; Alonso-Serrano, A.; Bastos, C.; Bertolami, O.

    2016-08-01

    We examine a new multiverse scenario in which the component universes interact. We focus our attention to the process of "true" vacuum nucleation in the false vacuum within one single element of the multiverse. It is shown that the interactions lead to a collective behavior that might lead, under specific conditions, to a pre-inflationary phase and ensued distinguishable imprints in the comic microwave background radiation.

  18. Vacuum decay in an interacting multiverse

    Energy Technology Data Exchange (ETDEWEB)

    Robles-Pérez, S. [Centro de Física “Miguel Catalán”, Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, Serrano 121, 28006 Madrid (Spain); Estación Ecológica de Biocosmología, Pedro de Alvarado, 14, 06411 Medellín (Spain); Alonso-Serrano, A. [Centro de Física “Miguel Catalán”, Instituto de Física Fundamental, Consejo Superior de Investigaciones Científicas, Serrano 121, 28006 Madrid (Spain); Estación Ecológica de Biocosmología, Pedro de Alvarado, 14, 06411 Medellín (Spain); School of Mathematics and Statistics, Victoria University of Wellington, PO Box 600, Wellington 6140 (New Zealand); Bastos, C., E-mail: catarina.bastos@tecnico.ulisboa.pt [GoLP, Instituto de Plasmas e Fusão Nuclear, Instituto Superior Técnico, Avenida Rovisco Pais 1, 1049-001 Lisboa (Portugal); Bertolami, O. [Departamento de Física e Astronomia and Centro de Física do Porto, Faculdade de Ciências da Universidade do Porto, Rua do Campo Alegre 687, 4169-007 Porto (Portugal)

    2016-08-10

    We examine a new multiverse scenario in which the component universes interact. We focus our attention to the process of “true” vacuum nucleation in the false vacuum within one single element of the multiverse. It is shown that the interactions lead to a collective behavior that might lead, under specific conditions, to a pre-inflationary phase and ensued distinguishable imprints in the comic microwave background radiation.

  19. Vacuum decay in an interacting multiverse

    Directory of Open Access Journals (Sweden)

    S. Robles-Pérez

    2016-08-01

    Full Text Available We examine a new multiverse scenario in which the component universes interact. We focus our attention to the process of “true” vacuum nucleation in the false vacuum within one single element of the multiverse. It is shown that the interactions lead to a collective behavior that might lead, under specific conditions, to a pre-inflationary phase and ensued distinguishable imprints in the comic microwave background radiation.

  20. Vacuum decay in an interacting multiverse

    International Nuclear Information System (INIS)

    Robles-Pérez, S.; Alonso-Serrano, A.; Bastos, C.; Bertolami, O.

    2016-01-01

    We examine a new multiverse scenario in which the component universes interact. We focus our attention to the process of “true” vacuum nucleation in the false vacuum within one single element of the multiverse. It is shown that the interactions lead to a collective behavior that might lead, under specific conditions, to a pre-inflationary phase and ensued distinguishable imprints in the comic microwave background radiation.