Sample records for vacuum annealing phenomena

  1. Vacuum Arc Anode Phenomena

    Microsoft Academic Search

    H. Craig Miller

    1983-01-01

    This paper briefly reviews anode phenomena in vacuum arcs, specially experimental work. It discusses, in succession, arc modes at the anode, anode temperature measurements, anode ions, transitions of the arc into various modes (principally the anode spot mode), and theoretical explanations of anode phenomena. The two most common anode modes in a vacuum arc are a low current mode where

  2. Vacuum Arc Anode Phenomena

    Microsoft Academic Search

    H. Craig Miller

    1977-01-01

    This paper presents a brief review of anode phenomena in vacuum arcs. It discusses in succession the transition of the arc into the anode spot mode; the temperature of the anode before, during, and after formation of an anode spot; and anode ions. Characteristically the anode spot has a temperature of the order of the atmospheric boiling point of the

  3. Vacuum arc recovery phenomena

    Microsoft Academic Search

    J. A. Rich; G. A. Farrall

    1964-01-01

    The present experimental and theoretical study has been designed to uncover the mechanism underlying the rapid recovery of electrical strength of a short vacuum gap after arcing. In the experiment the contacts were of gas-free silver and the contact area and gap length were varied. Recovery strength was measured following the forced extinction of a 250 amp arc in 0.5

  4. Vacuum arc ion currents and electrode phenomena

    Microsoft Academic Search

    C. W. Kimblin

    1971-01-01

    Properties of dc vacuum arcs between copper electrodes are studied in both a vacuum interrupter and a metal walled arc chamber. Maximum ion currents of ?8 to 20 percent of the arc current (100 to 3000 A) are drawn from the diffuse arc plasma when the bounding metal wall or shield is biased negative. This maximum ion current is a

  5. Controlling superconductivity in La2-xSrxCuO4+? by ozone and vacuum annealing

    DOE PAGESBeta

    Leng, Xiang; Bozovic, Ivan

    2015-01-01

    In this study we performed a series of ozone and vacuum annealing experiments on epitaxial La2-xSrxCuO4+? thin films. The transition temperature after each annealing step has been measured by the mutual inductance technique. The relationship between the effective doping and the vacuum annealing time has been studied. Short-time ozone annealing at 470 °C oxidizes an underdoped film all the way to the overdoped regime. The subsequent vacuum annealing at 350 °C to 380 °C slowly brings the sample across the optimal doping point back to the undoped, non-superconducting state. Several ozone and vacuum annealing cycles have been done on themore »same sample and the effects were found to be repeatable and reversible Vacuum annealing of ozone-loaded LSCO films is a very controllable process, allowing one to tune the doping level of LSCO in small steps across the superconducting dome, which can be used for fundamental physics studies.« less

  6. A Review of Anode Phenomena in Vacuum Arcs

    Microsoft Academic Search

    H. Craig Miller

    1985-01-01

    This paper discusses arc modes at the anode, anode temperature measurments, anode ions, transitions of the arc into various modes (principally the anode-spot mode), and theoretical explanations of anode phenomena. A vacuum arc can exhibit five anode discharge modes: 1) a low-current mode in which the anode is basically passive, acting only as a collector of particles emitted from the

  7. Vacuum annealing temperature on spray In2S3 layers

    NASA Astrophysics Data System (ADS)

    Bouguila, Nourredine; Timoumi, Abdelmajid; Bouzouita, Hassen

    2014-02-01

    Indium sulfide In2S3 thick films are deposited on glass substrates using spray technique over the optimum conditions experiments (Ts = 340 °C, S/In = 2). The films are polycrystalline and have thickness of about 1.8 ?m. These films are annealed in a vacuum sealed pyrex tubes (10-5 torr). Physico-chemical characterizations by SEM observation, X-ray diffraction and EDX analysis are undertaked on these films. This treatment has improved crystallinity of samples. It has allowed thus to stabilize ? and ? varieties of In2S3 material. In2O3 and In6S7 phases have appeared with very weak intensities at high temperatures. The best structure quality are obtained at 300 °C for the optimum annealed temperature (Ts = 340 °C, S/In = 2), for which samples are constituted in dominance by ? phase oriented preferentially towards (1 0 2). The grain size is 42 nm of this phase. Chemical composition of such films has changed relatively to non-treated film but it seems not be affected by treatment temperature. Atomic molar ratio S/In is obtained for 0.9. Optical study shows that these layers are transparent in the visible and optical direct band gap increases as function of annealed temperature.

  8. A review of anode phenomena in vacuum arces

    SciTech Connect

    Miller, H.C.

    1988-09-01

    This report discusses arc modes at the anode, experimental results pertinent to anode phenomena, and theoretical explanations of anode phenomena. The dominant mechanism controlling the formation of an anode spot appears to depend upon the electrode geometry, the electrode material, and the current waveforms of the particular vacuum arc being considered. In specific experimental conditions, either magnetic constriction in the gap plasma or gross anode melting or local anode evaporation can trigger the transition. However, the most probable explanation of anode spot formation is a combination theory, which considers magnetic constriction in the plasma together with the fluxes of material from the anode and cathode as well as the thermal, electrical, and geometric effects of the anode in analyzing the behavior of the anode and the nearby plasma. 88 refs., 6 figs., 8 tabs.

  9. Phase Transformation and RT Characteristics of Vacuum Annealed Vanadium Oxide Thin Films

    Microsoft Academic Search

    Y. L. Wang; M. C. Li; L. C. Zhao

    2008-01-01

    Polycrystalline vanadium oxide (VOx) thin films with mixed phases of V6O13 + VO2 (M) are deposited onto p-doped Si (100) substrates at 430°C using magnetron sputtering. By vacuum annealing on as-deposited VOx thin films at 450°C, at different annealing times we obtained nanoscale polycrystalline VOx thin films with two or more mixed phases. With the annealing time increasing, the phases

  10. PHASE TRANSFORMATION AND R–T CHARACTERISTICS OF VACUUM ANNEALED VANADIUM OXIDE THIN FILMS

    Microsoft Academic Search

    Y. L. WANG; M. C. LI; L. C. ZHAO

    2008-01-01

    Polycrystalline vanadium oxide (VOx) thin films with mixed phases of V6O13 + VO2 (M) are deposited onto p-doped Si (100) substrates at 430°C using magnetron sputtering. By vacuum annealing on as-deposited VOx thin films at 450°C, at different annealing times we obtained nanoscale polycrystalline VOx thin films with two or more mixed phases. With the annealing time increasing, the phases

  11. A Review of Arcing Phenomena in Vacuum and in the Transition to Atmospheric Pressure Arcs

    Microsoft Academic Search

    C. W. Kimblin

    1982-01-01

    This paper reviews vacuum-arc phenomena, and the effect of low-pressure gaseous ambients on electrode phenomena in the transition to atmospheric pressure arcs. The 5 main areas addressed are cathode-spot phenomena, anode-spot phenomena, the properties of the interelectrode plasma for both diffuse arcs and columnar arcs, the interaction of vacuum arcs with axial and transverse magnetic fields, and finally, the transition

  12. Development of fast heating electron beam annealing setup for ultra high vacuum chamber

    SciTech Connect

    Das, Sadhan Chandra [UGC-DAE Consortium For Scientific Research, University Campus, Khandwa Road, Indore 452 001, MP (India) [UGC-DAE Consortium For Scientific Research, University Campus, Khandwa Road, Indore 452 001, MP (India); School of Electronics, Devi Ahilya University, Indore 452001, MP (India); Institute of Physics, University of Greifswald, Felix Hausdroff Str. 6 (Germany); Majumdar, Abhijit, E-mail: majuabhijit@gmail.com, E-mail: majumdar@uni-greifswald.de; Hippler, R. [Institute of Physics, University of Greifswald, Felix Hausdroff Str. 6 (Germany)] [Institute of Physics, University of Greifswald, Felix Hausdroff Str. 6 (Germany); Katiyal, Sumant [School of Electronics, Devi Ahilya University, Indore 452001, MP (India)] [School of Electronics, Devi Ahilya University, Indore 452001, MP (India); Shripathi, T. [UGC-DAE Consortium For Scientific Research, University Campus, Khandwa Road, Indore 452 001, MP (India)] [UGC-DAE Consortium For Scientific Research, University Campus, Khandwa Road, Indore 452 001, MP (India)

    2014-02-15

    We report the design and development of a simple, electrically low powered and fast heating versatile electron beam annealing setup (up to 1000?°C) working with ultra high vacuum (UHV) chamber for annealing thin films and multilayer structures. The important features of the system are constant temperature control in UHV conditions for the temperature range from room temperature to 1000?ºC with sufficient power of 330 W, at constant vacuum during annealing treatment. It takes approximately 6 min to reach 1000?°C from room temperature (?10{sup ?6} mbar) and 45 min to cool down without any extra cooling. The annealing setup consists of a UHV chamber, sample holder, heating arrangement mounted on suitable UHV electrical feed-through and electronic control and feedback systems to control the temperature within ±1?ºC of set value. The outside of the vacuum chamber is cooled by cold air of 20?°C of air conditioning machine used for the laboratory, so that chamber temperature does not go beyond 50?°C when target temperature is maximum. The probability of surface oxidation or surface contamination during annealing is examined by means of x-ray photoelectron spectroscopy of virgin Cu sample annealed at 1000?°C.

  13. Wettability of ZnO: A comparison of reactively sputtered; thermally oxidized and vacuum annealed coatings

    Microsoft Academic Search

    Harish C. Barshilia; N. Selvakumar; Nisha Pillai; L. Mayura Devi; K. S. Rajam

    2011-01-01

    We have studied the wettability of sputter deposited ZnO, thermally oxidized Zn–ZnO and vacuum annealed ZnO coatings. The X-ray diffraction patterns showed the formation of hexagonal-wurtzite structure of ZnO, which was further confirmed by micro-Raman spectroscopy data. The X-ray photoelectron spectroscopy data indicated that the sputter deposited ZnO coatings were more stoichiometric than thermally oxidized Zn–ZnO and vacuum annealed ZnO

  14. Surface enhanced Raman scattering of aged graphene: Effects of annealing in vacuum

    NASA Astrophysics Data System (ADS)

    Wang, Yingying; Ni, Zhenhua; Li, Aizhi; Zafar, Zainab; Zhang, Yan; Ni, Zhonghua; Qu, Shiliang; Qiu, Teng; Yu, Ting; Xiang Shen, Ze

    2011-12-01

    In this paper, we report a simple method to recover the surface enhanced Raman scattering activity of aged graphene. The Raman signals of Rhodamine molecules absorbed on aged graphene are dramatically increased after vacuum annealing and comparable to those on fresh graphene. Atomic force microscopy measurements indicate that residues on aged graphene surface can efficiently be removed by vacuum annealing, which makes target molecule closely contact with graphene. We also find that the hole doping in graphene will facilitate charge transfer between graphene and molecule. These results confirm the strong Raman enhancement of target molecule absorbed on graphene is due to the charge transfer mechanism.

  15. Surface enhanced Raman scattering of aged graphene: Effects of annealing in vacuum

    SciTech Connect

    Wang Yingying; Li Aizhi; Qu Shiliang [Department of Optoelectronic Science, Harbin Institute of Technology at Weihai, Weihai 264209 (China); Ni Zhenhua; Zafar, Zainab; Qiu Teng [Department of Physics, Southeast University, Nanjing 211189 (China); Zhang Yan; Ni Zhonghua [Jiangsu Key Laboratory for Design and Fabrication of Micro-Nano Biomedical Instruments, School of Mechanical Engineering, Southeast University, Nanjing 211189 (China); Yu Ting; Shen Zexiang [Division of Physics and Applied Physics, School of Physical and Mathematical Sciences, Nanyang Technological University, 21 Nanyang Link, Singapore 637371 (Singapore)

    2011-12-05

    In this paper, we report a simple method to recover the surface enhanced Raman scattering activity of aged graphene. The Raman signals of Rhodamine molecules absorbed on aged graphene are dramatically increased after vacuum annealing and comparable to those on fresh graphene. Atomic force microscopy measurements indicate that residues on aged graphene surface can efficiently be removed by vacuum annealing, which makes target molecule closely contact with graphene. We also find that the hole doping in graphene will facilitate charge transfer between graphene and molecule. These results confirm the strong Raman enhancement of target molecule absorbed on graphene is due to the charge transfer mechanism.

  16. Mid-Infrared Spectral Evolution of Amorphous Magnesium Silicate Smokes Annealed in Vacuum: Comparison to Cometary Spectra

    Microsoft Academic Search

    Susan L. Hallenbeck; Joseph A. Nuth; Patricia L. Daukantas

    1998-01-01

    Amorphous magnesium silicate smokes were prepared by vapor phase condensation and annealed in vacuum. The samples were monitored by IR spectroscopy as a function of annealing time and temperature, focusing on the development of the 10 ?m silicate feature. The IR spectrum of the initial condensate displayed a broad band at 9.3 ?m. After annealing for 10.5 h at 1027

  17. The effects of vacuum annealing on the structure and surface chemistry of iron nanoparticles

    Microsoft Academic Search

    Thomas B. Scott; Michelle Dickinson; Richard A. Crane; Olga Riba; Gareth M. Hughes; Geoffrey C. Allen

    2010-01-01

    In order to increase the longevity of contaminant retention, a method is sought to improve the corrosion resistance of iron\\u000a nanoparticles (INP) used for remediation of contaminated water and thereby extend their industrial lifetime. A multi-disciplinary\\u000a approach was used to investigate changes induced by vacuum annealing (?8 mbar) at 500 °C on the bulk and surface chemistry of INP. The particle size

  18. Post arc phenomena in rapidly commutated diffuse vacuum arcs

    Microsoft Academic Search

    Mody

    1985-01-01

    The behavior of rapidly commutated (up to 1.2 kA\\/..mu..s) diffuse vacuum arcs was studied using three different interrupters: (a) GE 10-cm-diameter Cu electrode interrupter, (b) a GE 10-cm-diameter Be electrode interrupter, and (c) a VIL (V5) interrupter. These interrupters were tested using a synthetic test circuit that allowed independent variation of arc current prior to commutation. Post arc currents and

  19. Monte Carlo Simulation of Surface-Charging Phenomena on Insulators Prior to Flashover in Vacuum

    Microsoft Academic Search

    Kai-Kun Yu; Guan-Jun Zhang; Nan Zheng; Yevgeny Raitses; Nathaniel J. Fisch

    2009-01-01

    Before flashover across an insulator under high electric field in vacuum, there are charging phenomena occurring on the insulator surface, which significantly affect the developing process of flashover. Based on the secondary-electron-emission-avalanche model and by using the Monte Carlo method, a 2-D analysis of surface charge density on cylindrical and conical insulators prior to flashover in vacuum has been performed

  20. Surface charge and surface preflashover phenomena of alumina insulators in vacuum

    Microsoft Academic Search

    Lijian Ding; C. R. Li; Jingchun Wang; Wei Wang; Yangchun Cheng

    2000-01-01

    Investigations have been carried out on alumina insulators in vacuum under an impulse voltage (0.7\\/4 ?s) in order to study the relationship between surface charging and surface preflashover phenomena of insulators. The alumina insulators studied were 99.9% alumina cylindrical specimens and the employed electrode system is a non-uniform field electrode system. The surface preflashover phenomena was observed and the surface

  1. High-vacuum annealing reduction of Co/CoO nanoparticles.

    PubMed

    López Antón, R; González, J A; Andrés, J P; Canales-Vázquez, J; De Toro, J A; Riveiro, J M

    2014-03-14

    Porous films of Co/CoO magnetic nanoparticles have been obtained by inert gas condensation and partially oxidized in situ in the deposition chamber. These nanoparticle films were subjected to thermal treatments in high vacuum and the chemical and structural changes monitored by x-ray diffraction, transmission electron microscopy, transport and magnetic measurements (with a focus on the exchange-bias phenomenon), which evidence that for vacuum annealing temperatures above 360?°C, most of the CoO phase is reduced to metallic Co without requiring the presence of an external reducing agent (e.g., H?) or a plasma. Additionally, there is a certain degree of particle coalescence resulting in the formation of greater nanoparticles as the annealing temperature increases. This yields a smaller proportion of CoO compared to metallic Co and a reduction of the Co/CoO interface density, pinpointed by a drastic decrease of the exchange-bias field. The crucial roles of the vacuum level and the surface-to-volume ratio are evidenced by magnetic measurements, highlighting the potential of magnetometry as a probe for the reduction/oxidation of composite nanostructures. PMID:24532090

  2. High-vacuum annealing reduction of Co/CoO nanoparticles

    NASA Astrophysics Data System (ADS)

    López Antón, R.; González, J. A.; Andrés, J. P.; Canales-Vázquez, J.; De Toro, J. A.; Riveiro, J. M.

    2014-03-01

    Porous films of Co/CoO magnetic nanoparticles have been obtained by inert gas condensation and partially oxidized in situ in the deposition chamber. These nanoparticle films were subjected to thermal treatments in high vacuum and the chemical and structural changes monitored by x-ray diffraction, transmission electron microscopy, transport and magnetic measurements (with a focus on the exchange-bias phenomenon), which evidence that for vacuum annealing temperatures above 360?°C, most of the CoO phase is reduced to metallic Co without requiring the presence of an external reducing agent (e.g., H2) or a plasma. Additionally, there is a certain degree of particle coalescence resulting in the formation of greater nanoparticles as the annealing temperature increases. This yields a smaller proportion of CoO compared to metallic Co and a reduction of the Co/CoO interface density, pinpointed by a drastic decrease of the exchange-bias field. The crucial roles of the vacuum level and the surface-to-volume ratio are evidenced by magnetic measurements, highlighting the potential of magnetometry as a probe for the reduction/oxidation of composite nanostructures.

  3. Dynamics of arc phenomena at closure of electrical contacts in vacuum circuit breakers

    Microsoft Academic Search

    Stanislav N. Kharin; H. Nouri; D. Amft

    2005-01-01

    Dynamic phenomena accompanying electrical contact closure in vacuum circuit breakers are considered as consecutive stages, including breakdown, touch, compression, restitution, bridging, and arcing at bouncing. The hybrid mathematical model is elaborated to describe dynamics of the arc and forces acting in the contact gap. The model uses experimental oscillograms of current, voltage and contact displacement and nonlinear equations for arc,

  4. Annealing single-walled metallic carbon nanotube devices in ultra-high vacuum

    NASA Astrophysics Data System (ADS)

    Kane, Alexander Allen

    Single walled carbon nanotube (SWNT) devices were fabricated and annealed in ultra high vacuum (UHV) with simultaneous electrical characterization. As one-dimensional crystals with nanometer scale diameters and up to meter scale lengths, SWNTs offer a unique opportunity to probe 1D transport in mesoscopic electronics. Furthermore, all of the atoms in SWNTs are surface atoms which means that the electronic properties can be examined and tailored using the well-developed tools of surface chemistry. However, electronic resistances and noise for technologically relevant small-diameter SWNT devices are too high for commercial applications. In this work, intrinsic and extrinsic sources of scattering in SWNTs were examined by heating SWNT field effect transistors in UHV with while monitoring changes in the devices' resistance, transconductance, and conductance fluctuations. The effects of the contact interface were studied by varying the electrode metal, including palladium, titanium, and platinum contacts. It was found that metal-SWNT contact interfaces are the primary scatterers in devices as fabricated, but the contact resistance can be greatly reduced by annealing to a limit that depends primarily on the surface chemistry of the electrode metal and the geometry of the interface. Secondary sources of scattering include surface adsorbates on the electrodes and substrate, sub-strate oxide phonons and SWNT phonons. Adsorbates are the primary source of 1/f conductance noise, followed by the electrode interface. Annealing devices in UHV was found to reduce the contact resistance, noise, and device to device inhomogeneity. Graphene, formed through catalysis on the Pt surface during the anneal, was found to make the best contact to SWNTs, rather than the conventional Pd, Ti, and Pt, both in terms of contact resistance and noise.

  5. Annealing effects of tantalum films on Si and SiO2/Si substrates in various vacuums

    NASA Astrophysics Data System (ADS)

    Liu, Ling; Wang, Yue; Gong, Hao

    2001-07-01

    The annealing effects of 550 nm thick ?-Ta films sputtered on Si and SiO2 substrates have been investigated under various vacuum conditions. Phase transformation from the tetragonal ?-Ta into body-centered-cubic ?-Ta of much higher conductivity occurred at annealing temperatures lower than 500 °C and 80% of ?-Ta transformed into ?-Ta after annealing at 600 °C for Ta on a Si substrate. For Ta on a SiO2 substrate, no phase transformation was observed at 500 °C annealing, and only 20% of ?-Ta transformed into ?-Ta at 600 °C. Oxygen diffusion into the Ta film at the interface of Ta/SiO2 could hinder ?-Ta to ?-Ta transformation. Both Ta on Si and Ta on SiO2 samples have smooth surfaces after annealing in 2×10-5 Torr. After annealing in a vacuum lower than 2×10-4 Torr, surface oxidation of the Ta thin films was detected. The increase of oxygen content in the Ta films caused higher compressive stress, and resulted in the film peeling in a serpentine pattern during annealing at 500 °C in 2×10-2 Torr for Ta on a SiO2 substrate. The Ta films cracked and detached from the SiO2 substrate after being annealed at 750 °C in 2×10-2 Torr. In contrast, no crack was found in Ta on Si, probably because of the relief of film stress due to more ?-Ta being transformed into ?-Ta during annealing. The residual oxygen and moisture in low vacuum may build up stress in Ta thin films during thermal processes, which can cause major reliability problems in electronic and other applications.

  6. Vacuum annealing effects on the surface stoichiometry of InGaAsP

    SciTech Connect

    Yeh, J.L.; Siu, S.Z. (Dept. of Electrical and Computer Engineering, Rutgers Univ., Piscataway, NJ (US)); Vasile, M.J.; Schwartz, B. (AT and T Bell Lab., Murray Hill, NJ (US))

    1990-04-01

    The use of the binary and quaternary systems InP and In{sub 1{minus}x}Ga{sub x}As{sub 1{minus}y}P{sub y} for the fabrication of long wavelengths (i.e., 1.3-1.6{mu}m) LED's and lasers is a well-established approach. Our work is focused on the quaternay (Q) materials, with the major emphasis being on the surface chemistry of epitaxially grown Q-layers, lattice matched to InP and photoluminescing at about 1.3 {mu}m. In this paper the authors report on a surface stoichiometry shift that has been observed on annealing Q-layers up to about 600{degrees}C in a vacuum ({approximately}10{sup {minus}9} Torr).

  7. INVESTIGATION OF THE ELECTROCAPILLARY PHENOMENA IN BISMUTH-CADMIUM ALLOYS AND OF THE SURFACE TENSION OF THE ALLOYS IN VACUUM

    Microsoft Academic Search

    V. A. Kuznetsov; T. D. Dyakova; V. P. Maltseva

    1959-01-01

    A study was made of the electrocapillary phenomena in Cd- Bi alloys and ; of the surface tension of these alloys in vacuum at 450 deg C. Increase in ; concentration of bismuth in the alloy was shown to lower the surface tension of ; the latter both at the electrolyte interface and in vacuum. Calculations were ; made of

  8. XANES and XPS studies of processes initiated by high-vacuum annealing in SnO x /MWCNT composite layers

    NASA Astrophysics Data System (ADS)

    Bolotov, V. V.; Korusenko, P. M.; Nesov, S. N.; Povoroznyuk, S. N.; Shelyagin, R. V.

    2013-06-01

    The initial and thermally treated composites based on SnO x /MWCNT have been studied by the XANES and XPS methods using the equipment of the BESSY II Russian-German beamline of synchrotron radiation and by the AES and HRTEM methods. The characteristic mechanisms of chemical and structural transformations in the SnO x phase have been determined depending on the vacuum annealing temperature. It has been found that the basic process in the metal-oxide component at annealing temperatures not exceeding 500°C is the tin monoxide SnO disproportionation reaction with the formation of the dioxide SnO2 phase and metallic tin. An increase in the annealing temperature to 800°C results in the activation of carbothermal reduction of metallic tin in contact areas of oxide clusters and MWCNT, as well as in the formation of nanocrystalline structures in the metal-oxide component of composite.

  9. The effects of vacuum annealing on the structure and surface chemistry of iron:nickel alloy nanoparticles

    Microsoft Academic Search

    Michelle Dickinson; Thomas B. Scott; Richard A. Crane; Olga Riba; Robert J. Barnes; Gareth M. Hughes

    2010-01-01

    In order to increase the longevity of contaminant retention on the particle surface, a method is sought to improve the corrosion\\u000a resistance of bimetallic iron nickel nanoparticles (INNP) used for the remediation of contaminated water, and thereby extend\\u000a their industrial lifetime. A multi-disciplinary approach was used to investigate changes induced by vacuum annealing (?8 mbar) at 500 °C on the bulk and

  10. Structural, optical and electrical properties of In 2Se 3 thin films formed by annealing chemically deposited Se and vacuum evaporated In stack layers

    Microsoft Academic Search

    K. Bindu; C Sudha Kartha; K. P Vijayakumar; T Abe; Y Kashiwaba

    2002-01-01

    Indium selenide thin films were prepared by annealing the Se–In stack layers in high vacuum. Selenium film was deposited using chemical bath deposition and indium film, using vacuum evaporation. Annealing temperatures were varied from 373 to 723K. Properties of these films were investigated using different analytical techniques. X-ray diffraction studies revealed that polycrystalline and amorphous ?-In2Se3 films were obtained depending

  11. Controlling superconductivity in La2-xSrxCuO4+? by ozone and vacuum annealing

    SciTech Connect

    Leng, Xiang [Brookhaven National Lab. (BNL), Upton, NY (United States); Bozovic, Ivan [Brookhaven National Lab. (BNL), Upton, NY (United States)

    2015-01-01

    In this study we performed a series of ozone and vacuum annealing experiments on epitaxial La2-xSrxCuO4+? thin films. The transition temperature after each annealing step has been measured by the mutual inductance technique. The relationship between the effective doping and the vacuum annealing time has been studied. Short-time ozone annealing at 470 °C oxidizes an underdoped film all the way to the overdoped regime. The subsequent vacuum annealing at 350 °C to 380 °C slowly brings the sample across the optimal doping point back to the undoped, non-superconducting state. Several ozone and vacuum annealing cycles have been done on the same sample and the effects were found to be repeatable and reversible Vacuum annealing of ozone-loaded LSCO films is a very controllable process, allowing one to tune the doping level of LSCO in small steps across the superconducting dome, which can be used for fundamental physics studies.

  12. Enhanced reactivity of nanoscale iron particles through a vacuum annealing process

    Microsoft Academic Search

    Olga RibaRobert; Robert J. Barnes; Thomas B. Scott; Murray N. Gardner; Simon A. Jackman; Ian P. Thompson

    A reactivity study was undertaken to compare and assess the rate of dechlorination of chlorinated aliphatic hydrocarbons (CAHs)\\u000a by annealed and non-annealed nanoscale iron particles. The current study aims to resolve the uncertainties in recently published\\u000a work studying the effect of the annealing process on the reduction capability of nanoscale Fe particles. Comparison of the\\u000a normalized rate constants (m2\\/h\\/L) obtained

  13. Color center annealing in gamma - irradiated polystyrene, under vacuum and air atmospheres

    Microsoft Academic Search

    J. S. Wallace; M. B. Sinclair; K. T. Gillen; R. L. Clough

    1993-01-01

    A primary effect of low doses of ionizing radiation on polystyrene is the production of absorption centers in the UV and Visible regions of the spectrum. There are two types of color centers: ``annealable'' and ``permanent''. Annealable centers are most likely due to the formation of cyclohexadienyl, radicals in the polymer. These species have not only strong UV absorption bands

  14. Influence of annealing on the optical properties of vacuum deposited silver thin films

    NASA Astrophysics Data System (ADS)

    Gnanadurai, P.; Sivaraja, N.; Soundrarajan, N.; Vijayan, C.

    2015-06-01

    Thin Silver films of thickness 15nm were prepared by thermal evaporation on well cleaned glass substrates at room temperature at a pressure of 2×10-5 mbar with the deposition rate of 0.01À/sec and annealed in air for an hour at temperatures between 300°c and 400°c. The prepared films were characterized by X-ray diffraction (XRD), UV-visible spectroscopy and AFM. The mean grain size of the film at different annealing temperatures was determined by the X-ray diffraction pattern by using Scheer's formula. It is found that from absorbance studies surface Plasmon peak position decreases as the annealing temperature increases and blue shifted. And also from transmittance studies the thermal effect of silver film strongly affects the optical transmittance. From AFM studies the average particle size and RMS surface roughness increase with increase of annealing temperatures.

  15. Electrical activation phenomena induced by excimer laser annealing in B-implanted silicon

    SciTech Connect

    Fortunato, G.; Mariucci, L.; La Magna, A.; Alippi, P.; Italia, M.; Privitera, V.; Svensson, B.; Monakhov, E. [IFN-CNR, Via Cineto Romano 42, 00156 Rome (Italy); IMM-CNR, Stradale Primosole 50, 95121 Catania (Italy); University of Oslo, P.O. Box 1048 Blindern, N-0316 Oslo (Norway)

    2004-09-20

    The activation process induced by excimer laser annealing (ELA) has been investigated in 10 keV B-implanted samples. It is found that for energy densities inducing melt depths of the order or larger of the implanted region the junction depth is controlled by the melt depth, with activation approaching 100% and box-shaped carrier density distributions with abrupt junction profile. For energy densities inducing a melting shallower than the implanted region, two different activation mechanisms have been identified: the first occurring in the molten region and leading to complete B activation; the second occurring in the region immediately below the molten zone and leading to thermal activation of B, induced by the heat wave propagating into the Si wafer. This last process is characterized by an activation energy of 5 eV and is not accompanied by B diffusion. As a consequence, a deep tail of active B is produced, preventing the possibility to form abrupt and ultrashallow junctions. These results suggest that for the formation of ultrashallow junctions it is essential to combine ELA with ultralow energy ion implantation.

  16. The evolution of chemical nature on U-0.79 wt.%Ti surface during vacuum annealing

    NASA Astrophysics Data System (ADS)

    Shi, Peng; Luo, Lizhu; Zhao, Yawen; Fu, Xiaoguo; Ao, Bingyun; Bai, Bin; Wang, Xiaolin

    2015-07-01

    The evolution of the oxide-overlayer's chemical nature on the surface of U-0.79 wt.%Ti alloy during vacuum annealing has been examined in situ by X-ray photoelectron spectroscopy (XPS). A specimen sheet of the alloy covered by oxide films is heated from room temperature to 700 °C in vacuum. It is found that the UO2+x outer oxide layer starts to be reduced to UO2 at 200 °C. Between 300 and 400 °C, an oxycarbide (UOxCy) layer is observed due to the reaction between UO2 and carbon. Above 500 °C, UOxCy decomposes and the surface covered oxide layer starts to be reduced to the metallic state, meanwhile, a thermal driven segregation of Ti to the surface is also observed.

  17. Low-energy ion scattering spectroscopy observations of c-axis-oriented YBa2Cu3O(7-x) thin films - Effects of in-vacuum annealing

    Microsoft Academic Search

    S. Tanaka; T. Nakamura; M. Iiyama; N. Yoshida; S. Takano; F. Shoji; K. Oura

    1991-01-01

    The atomic structure of (001) surfaces of c-axis-oriented YBa2Cu3O(7-x) (YBCO) thin films was studied by low-energy ion scattering spectroscopy (ISS) after annealing in ultrahigh vacuum. This is the first report on the surface analysis of superconducting oxide evaluated by ISS. A clean surface of YBCO (001) 1 x 1 is produced by annealing at around 500 C. The surface structure

  18. Structural and optical properties of Ti-doped ZnO thin films prepared by the cathodic vacuum arc technique with different annealing processes

    Microsoft Academic Search

    Chun-Sen Wu; Bor-Tsuen Lin; Ru-Yuan Yang

    2011-01-01

    Highly transparent Ti-doped ZnO thin films were prepared on glass substrates at a deposition rate of approximately 33nm\\/min using the cathodic vacuum arc technique with a Zn target power of 550W and a Ti target power of 750W, respectively. X-ray diffraction measurements have shown that the Ti-doped ZnO thin film with a vacuum post-annealing condition is c-axis oriented but an

  19. Solid state interdiffusions in epitaxial Fe/GaAs(001) heterostructures during ultrahigh vacuum annealings up to 450 °C

    NASA Astrophysics Data System (ADS)

    Lépine, B.; Ababou, S.; Guivarc'h, A.; Jézéquel, G.; Députier, S.; Guérin, R.; Filipe, A.; Schuhl, A.; Abel, F.; Cohen, C.; Rocher, A.; Crestou, J.

    1998-03-01

    We have used a set of complementary experimental techniques to characterize an epitaxial structure (25 nm Fe)/GaAs(001) annealed at 450 °C under ultrahigh vacuum conditions. The solid state interdiffusion leads to the formation of an epitaxial reaction layer made of Fe2As patches embedded in a Ga rich Fe3Ga2-XAsX ternary phase. The epitaxial character of this layer explains how the usually reported epitaxial growth of Fe on GaAs performed in the temperature range of 175 to 225 °C is possible in spite of the species intermixing occurring at the interface. Moreover, the observed grains of Fe2As explain the decrease of magnetization at the interface in such contact, since Fe2As is an antiferromagnetic alloy.

  20. Growth of SiC thin films on (100) and (111) silicon by pulsed laser deposition combined with a vacuum annealing process

    SciTech Connect

    Huang, J.; Wang, L.; Wen, J.; Wang, Y.; Lin, C.; Zetterling, C.M.; Oestling, M.

    1999-07-01

    Crystalline 3C-SiC thin films were successfully grown on (100) and (111) Si substrates by using ArF pulsed laser ablation from a SiC ceramic target combined with a vacuum annealing process. X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR) were employed to study the effect of annealing on the structure of thin films deposited at 800 C. It was demonstrated that vacuum annealing could transform the amorphous SiC films into crystalline phase and that the crystallinity was strongly dependent on the annealing temperature. For the samples deposited on (100) and (111) Si, the optimum annealing temperatures were 980 and 920 C, respectively. Scanning electron microscope (SEM) micrographs exhibited different characteristic microstructure for the (100) and (111) Si cases, similar to that observed for the carbonization layer initially formed in chemical vapor deposition of SiC films on Si. This also showed the presence of the epitaxial relationship of 3C-SiC[100]//Si[100] and 3C-SiC[111]//Si[111] in the direction of growth.

  1. High-Vacuum Annealing of Polythiophene:Methanofullerene Bulk Heterojunction Solar Cells

    NASA Astrophysics Data System (ADS)

    Segui, Jennifer; Gearba, Ioana; Rafailovich, Miriam; Black, Charles

    2009-03-01

    Solar cell device architectures incorporating photoactive layers of immiscible blends of organic semiconductors achieve improved photovoltaic power conversion efficiency compared to planar device geometries. We have fabricated bulk heterojunction solar cells with active layer blends of poly-3 hexylthiophene (P3HT) and the fullerene derivative, [6,6] phenyl C61-butyric acid methyl ester (PCBM). Spin casting the blend from a chlorobenzene solution forms nanometer-scale domains of electron donor and acceptor phases in the device active layer. We solution process the active layers in ambient atmospheric conditions prior to aluminum contact evaporation resulting in inevitable oxygen adsorption in the P3HT bulk and interfaces. We have investigated several device post-fabrication thermal treatments for driving oxygen from the device active layer, including different temperatures, times, and vacuum pressures. We evaluate the efficacy of this technique in improving Al contact quality, film morphology, solar cell efficiency, and reproducibility via analysis of device current-voltage characteristics and tapping mode atomic force microscopy.

  2. Optical, electrical and structural characteristics of Al:ZnO thin films with various thicknesses deposited by DC sputtering at room temperature and annealed in air or vacuum

    Microsoft Academic Search

    C. Guillén; J. Herrero

    2010-01-01

    Transparent and conductive Al-doped ZnO (AZO) films have been grown with various thicknesses between 0.3 and 1.1 ?m by magnetron sputtering at room temperature onto soda lime glass substrates. After deposition, the samples have been annealed at temperatures ranging from 150 to 450 °C in air or vacuum. The optical, electrical, and structural characteristics of the AZO coatings have been analyzed as

  3. Vanishing of Vacuum States and Blow-up Phenomena of the Compressible Navier-Stokes Equations

    Microsoft Academic Search

    Hai-Liang Li; Jing Li; Zhouping Xin

    2008-01-01

    The Navier-Stokes systems for compressible fluids with density-dependent viscosities are considered in the present paper.\\u000a These equations, in particular, include the ones which are rigorously derived recently as the Saint-Venant system for the\\u000a motion of shallow water, from the Navier-Stokes system for incompressible flows with a moving free surface [14]. These compressible\\u000a systems are degenerate when vacuum state appears. We

  4. Effect of non-vacuum thermal annealing on high indium content InGaN films deposited by pulsed laser deposition.

    PubMed

    Wang, Tzu-Yu; Ou, Sin-Liang; Shen, Kun-Ching; Wuu, Dong-Sing

    2013-03-25

    InGaN films with 33% and 60% indium contents were deposited by pulsed laser deposition (PLD) at a low growth temperature of 300 °C. The films were then annealed at 500-800 °C in the non-vacuum furnace for 15 min with an addition of N(2) atmosphere. X-ray diffraction results indicate that the indium contents in these two films were raised to 41% and 63%, respectively, after annealing in furnace. In(2)O(3) phase was formed on InGaN surface during the annealing process, which can be clearly observed by the measurements of auger electron spectroscopy, transmission electron microscopy and x-ray photoelectron spectroscopy. Due to the obstruction of indium out-diffusion by forming In(2)O(3) on surface, it leads to the efficient increment in indium content of InGaN layer. In addition, the surface roughness was greatly improved by removing In(2)O(3) with the etching treatment in HCl solution. Micro-photoluminescence measurement was performed to analyze the emission property of InGaN layer. For the as-grown InGaN with 33% indium content, the emission wavelength was gradually shifted from 552 to 618 nm with increasing the annealing temperature to 800 °C. It reveals the InGaN films have high potential in optoelectronic applications. PMID:23546117

  5. Characterization of mixed titanium-niobium oxide Ti2Nb10O29 annealed in vacuum as anode material for lithium-ion battery

    NASA Astrophysics Data System (ADS)

    Takashima, Toshiki; Tojo, Tomohiro; Inada, Ryoji; Sakurai, Yoji

    2015-02-01

    In this paper, the properties of mixed titanium-niobium oxide Ti2Nb10O29 (TNO) annealed in air and vacuum as anode material for lithium-ion battery were investigated. The color of TNO annealed in vacuum (V-TNO) is dark blue while white for TNO annealed in air (A-TNO). Moreover, lattice parameters for V-TNO were confirmed to be slightly larger than those for A-TNO. Introduction of oxygen defect in V-TNO was confirmed by thermogravimetric analysis. X-ray photoelectron spectroscopy analysis also indicated that Ti4+ in V-TNO are partially reduced into Ti3+, due to the introduction of oxygen defect in V-TNO. Electronic conductivity at room temperature for uni-axially pressed V-TNO powder is estimated to be around 10-6-10-5 S cm-1, which is more than three digits higher than that for pressed A-TNO powder (= 10-9 S cm-1). The enhancement of intrinsic electronic conductivity of TNO greatly contributes for improving the rate performance. At low current density of 0.5 mA cm-2, both A-TNO and V-TNO showed reversible capacity around 250 mAh g-1 at potential range from 1.0 to 2.5 V vs. Li/Li+, while at higher current density of 10 mA cm-2, V-TNO maintained much higher discharge capacity of 150 mAh g-1 than that for TNO (= 50 mAh g-1).

  6. Low-energy ion scattering spectroscopy observations of c -axis-oriented YBa sub 2 Cu sub 3 O sub 7 minus x thin films: Effects of in-vacuum annealing

    Microsoft Academic Search

    S. Tanaka; T. Nakamura; M. Iiyama; N. Yoshida; S. Takano; F. Shoji; K. Oura

    1991-01-01

    The atomic structure of (001) surfaces of {ital c}-axis-oriented YBaâCuâO{sub 7-{ital x}} (YBCO) thin films was studied by low-energy ion scattering spectroscopy (ISS) after annealing in ultrahigh vacuum. This is the first report on the surface analysis of superconducting oxide evaluated by ISS. A clean surface of YBCO (001) 1Ã1 is produced by annealing at around 500 °C. The surface

  7. Characteristics of Al-doped ZnO thin films prepared in Ar + H{sub 2} atmosphere and their vacuum annealing behavior

    SciTech Connect

    Zhu, Bailin; Lü, Kun; Wang, Jun; Li, Taotao; Wu, Jun [Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan 430081 (China)] [Key Laboratory for Ferrous Metallurgy and Resources Utilization of Ministry of Education, Wuhan University of Science and Technology, Wuhan 430081 (China); Zeng, Dawen; Xie, Changsheng [Department of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)] [Department of Materials Science and Engineering, Huazhong University of Science and Technology, Wuhan 430074 (China)

    2013-11-15

    The microstructure and electrical–optical properties of Al-doped ZnO (AZO) films have been studied as a function of H{sub 2} flux in the magnetron sputtering process at 150 °C and postannealing temperature in vacuum. As H{sub 2} flux increases in the sputtering gas, the AZO films deposited have a (002) preferred orientation rather than the mixed (100) and (002) orientations, the grain size shows a tendency to first increase then decrease, and (002) diffraction peak position is inclined to shift to higher angles first then to lower angles. The resistivity of the films first decreases then increases with H{sub 2} flux, and the lowest resistivity of 4.02 × 10{sup ?4}? cm is obtained at a H{sub 2} flux of 10 sccm. The average transmittance in the visible region shows little dependence on H{sub 2} flux. As a whole, the AZO films with higher values of figure of merit are obtained when the H{sub 2} flux is in the range of 6–12 sccm. The AZO films deposited in Ar and Ar + H{sub 2} exhibit different annealing behaviors. For the AZO film deposited in Ar, the grain size gradually increases, the stresses are relaxed, the resistivity first decreases then increases, and the average transmittance in the visible region is unchanged initially then somewhat decreased as annealing temperature is increased. The optimum annealing temperature for improving properties of AZO films deposited in Ar is 300 °C. For the AZO films deposited in Ar + H{sub 2}, annealing does not significantly change the microstructure but increases the resistivity of the films; the average transmittance in the visible region remains unchanged initially but greatly reduced with further increase in annealing temperature. The carrier transport in the as-deposited and annealed films appears to be controlled by a mechanism of grain boundary scattering, and the value of E{sub g} increases with the increase in carrier concentration due to Burstein–Moss effect.

  8. Temperature-dependent phase separation during annealing of Ge2Sb2Te5 thin films in vacuum

    NASA Astrophysics Data System (ADS)

    Zhang, Zheng; Pan, Jisheng; Fang, Lina Wei-Wei; Yeo, Yee-Chia; Foo, Yong Lim; Zhao, Rong; Shi, Luping; Tok, Eng Soon

    2012-06-01

    Thermal stability of 100 nm Ge2Sb2Te5 thin film during annealing from room temperature to 240 °C inside a UHV chamber was studied in situ by X-ray photoelectron spectroscopy (XPS) and ex situ by X-ray diffraction (XRD) and atomic force microscopy (AFM). Ge species are found to diffuse preferentially to the surface when GST film is annealed from 25 °C to 100 °C. This process is accompanied by a change of phase whereby the amorphous film completely becomes face-center-cubic (FCC) phase at 100 °C. From 100 °C to 200 °C, both Sb and Te species are observed to diffuse more to the surface. The FCC phase is partially changed into hexagonal-close-pack (HCP) phase at 200 °C. At 220 °C, FCC phase is completely transformed into HCP phase. Loss of Sb and Te are also detected from the surface and this is attributed to desorption due to their high vapor pressures. At 240 °C, Sb and Te species are found to have desorbed completely from the surface, and leave behind Ge-rich 3D droplets on the surface. The separation of Ge2Sb2Te5 into Sb,Te-rich phase and Ge-rich phase is thus the main mechanism to account for the failure of Ge2Sb2Te5-based phase change memory devices under thermal stress.

  9. Annealing effect on the particle size and chemical composition of activated carbon obtained from vacuum furnace of teak sawdust

    SciTech Connect

    Armynah, B., E-mail: dtahir@fmipa.unhas.ac.id; Tahir, D., E-mail: dtahir@fmipa.unhas.ac.id; Jaya, N., E-mail: dtahir@fmipa.unhas.ac.id [Department of Physics, Hasanuddin University, Makassar 90245 (Indonesia)

    2014-09-25

    Activated carbon was produced from sawdust by using physical method in a high temperature vacuum furnace without additional chemical. Fast pyrolysis process was carried out prior in fluidized a bed furnace to produce char before activation process. Experiments were conducted to investigate the influence of various process parameters such as particle size, activation temperature and activation time on the quality of the activated carbon. In addition, the chemical composition studies were done by using x-ray fluorescence (XRF) spectroscopy. The crystallite sizes were calculated by using Scherer equation based on x-ray diffraction (XRD) spectroscopy data. The pyrolysis temperature and time were varied from 600°C to 900°C and from 3 hours to 6 hours, respectively. The particle size of activated carbon was increase with increasing temperature. The composition and crystallite size of the prepared activated carbon was compared with the non-activated carbon. The results indicated that the teak sawdust carbon could be employed as a low cost alternative to produce commercial activated carbon.

  10. Effect of Annealing Temperature on Tribological Properties and Material Transfer Phenomena of CrN and CrAlN Coatings

    NASA Astrophysics Data System (ADS)

    Wang, Linlin; Nie, X.

    2013-10-01

    This study evaluates the effects of annealing temperature and of the oxides produced during annealing processes on the tribological properties and material transfer behavior between the PVD CrN and CrAlN coatings and various counterface materials, i.e., ceramic alumina, steel, and aluminum. CrAlN coating has better thermal stability than CrN coating in terms of hardness degradation and oxidation resistance. When sliding against ceramic Al2O3 counterface, both CrN and CrAlN coatings present excellent wear resistance, even after annealing at 800 °C. The Cr-O compounds on the coating surface could serve as a lubricious layer and decrease the coefficient of friction of annealed coatings. When sliding against steel balls, severe material transfer and adhesive wear occurred on the CrN and CrAlN coatings annealed at 500 and 700 °C. However, for the CrAlN coating annealed at 800 °C, much less material sticking and only small amount of adhesive wear occurred, which is possibly due to the formation of a continuous Al-O layer on the coating outer layer. The sliding tests against aluminum balls indicate that both coatings are not suitable as the tool coatings for dry machining of aluminum alloys.

  11. Accelerated formation of metal oxide thin film at 200 °C using oxygen supplied by a nitric acid additive and residual organic suction vacuum annealing for thin-film transistor applications.

    PubMed

    Jeong, Woong Hee; Kim, Dong Lim; Kim, Hyun Jae

    2013-09-25

    Oxide semiconductors have gradually replaced amorphous and polycrystalline silicon for thin-film transistor (TFT) because of their high mobility and large-area uniformity. Especially, the oxide semiconductors have also achieved the low-cost manufacturing using a solution process. However, because the solution-processed oxide semiconductors require a high thermal energy to form the oxide thin film, the additional solution synthesis and annealing process are needed for low-temperature solution process. Because the conventional solution-processed oxide thin films have low oxidation level and high residual organic concentration at low annealing temperature, we propose the novel solution process that includes the nitric acid additive and the vacuum ambient annealing as an oxidizing agent and a residual organic suction, respectively. Therefore, we have successfully developed the simple oxide solution process and the soluble InZnO TFT with high field-effect mobility of 3.38 cm(2)/(V s) at 200 °C. PMID:23962037

  12. Infrared thermal annealing device

    NASA Astrophysics Data System (ADS)

    Gladys, M. J.; Clarke, I.; O'Connor, D. J.

    2003-07-01

    A device for annealing samples within an ultrahigh vacuum (UHV) scanning tunneling microscopy system was designed, constructed, and tested. The device is based on illuminating the sample with infrared radiation from outside the UHV chamber with a tungsten projector bulb. The apparatus uses an elliptical mirror to focus the beam through a sapphire viewport for low absorption. Experiments were conducted on clean Pd(100) and annealing temperatures in excess of 1000 K were easily reached.

  13. Nanomechanical characteristics of annealed Si/SiGe superlattices

    NASA Astrophysics Data System (ADS)

    Wu, Ming-Jhang; Wen, Hua-Chiang; Wu, Shyh-Chi; Yang, Ping-Feng; Lai, Yi-Shao; Hsu, Wen-Kuang; Wu, Wen-Fa; Chou, Chang-Pin

    2011-08-01

    In this study, the nanomechanical damage was investigated on the annealed Si/SiGe strained-layer superlattices (SLSs) deposited using an ultrahigh-vacuum chemical vapor deposition (UHVCVD). Nanoscratch, nanoindenter, atomic force microscopy (AFM), and transmission electron microscopy (TEM) techniques were used to determine the nanomechanical behavior of the SiGe films. With a constant force applied, greater hardness number and larger coefficients of friction ( ?) were observed on the samples that had been annealed at 600 °C, suggesting that annealing of the Si/SiGe SLSs can induce greater shear resistance. AFM morphological studies of the Si/SiGe SLSs revealed that pile-up phenomena occurred on both sides of each scratch, with the formation of some pellets and microparticles. The Si/SiGe SLSs that had been subjected to annealing under various conditions exhibited significantly different features in their indentation results. Indeed, the TEM images reveal slight dislocation propagation in the microstructures. Thus, the hardness and elastic modulus can be increased slightly after annealing treatment because the existence of comparatively unstable microstructures. It is suggested that cracking phenomena dominate the damage cause of Si/SiGe SLSs.

  14. Heating steels in vacuum

    SciTech Connect

    Marmer, E.N.

    1983-03-01

    It is recommended that high-strength and corrosion-resistant steels be heated in an electric vacuum furnace. Absence of oxidation and decarburization, decrease in the deformation of the part, increase in service life, plus safety, and nontoxicity in the shop, are cited as advantages. Annealing, carburizing, hardening, brazing, and sintering--all detailed-can be more efficiently accomplished in vacuum heating. As vacuum heating requires certain surface conditions, the compositions of residual mediums is studied. The microrelief and surface finish obtained after vacuum heating is determined. Annealing in a vacuum is compared to annealing in air, a depletion in manganese indicating a greater savings by use of vacuum. Ductility is also tested. The gas of special purity nitrogen is recommended for best results. In general, then, use of electric vacuum furnaces is recommended.

  15. Low-energy ion scattering spectroscopy observations of c -axis-oriented YBa sub 2 Cu sub 3 O sub 7 minus x thin films: Effects of in-vacuum annealing

    SciTech Connect

    Tanaka, S.; Nakamura, T.; Iiyama, M. (Information and Electronics Laboratories, Sumitomo Electric Industries, Ltd., 1-1-3, Shimaya, Konohana-ku, 554 Osaka (Japan)); Yoshida, N.; Takano, S. (Osaka Research Laboratories, Sumitomo Electric Industries, Ltd., 1-1-3, Shimaya, Konohana-ku, Osaka 554 (Japan)); Shoji, F.; Oura, K. (Faculty of Engineering, Osaka University, 2-1, Yamada-oka, Suita, Osaka 565 (Japan))

    1991-12-30

    The atomic structure of (001) surfaces of {ital c}-axis-oriented YBa{sub 2}Cu{sub 3}O{sub 7{minus}{ital x}} (YBCO) thin films was studied by low-energy ion scattering spectroscopy (ISS) after annealing in ultrahigh vacuum. This is the first report on the surface analysis of superconducting oxide evaluated by ISS. A clean surface of YBCO (001) 1{times}1 is produced by annealing at around 500 {degree}C. The surface structure is discussed in terms of the blocking and the nonblocking effects caused by the desorption of O(4) atoms. We conclude that the (001) surfaces are stabilized by Cu(1)-O chains.

  16. Study of the effect of thermal annealing on the optical and electrical properties of vacuum evaporated amorphous thin films in the system Ge20Te80-xBix

    NASA Astrophysics Data System (ADS)

    Bhatia, K. L.; Kishore, Nawal; Malik, Jitender; Singh, Mahender; Kundu, R. S.; Sharma, Ashwani; Srivastav, B. K.

    2002-03-01

    We systematically studied the effect of thermal annealing on the optical and electrical properties of amorphous semiconducting thin films in the system Ge20Te80-xBix (x = 0, 0.19, 2.93, 7.35) prepared by flash evaporation in a vacuum of 1 × 10-6 Torr. The films are characterized by x-ray diffraction (XRD) and electron probe micro analysis. The annealing temperature is kept at 150 °C, 180 °C and 220 °C. No crystallization of the thin films is achieved on annealing up to the temperature of 150 °C. At a higher temperature of annealing, microcrystals of Te, Bi2Te3, Ge-Te, etc, are observed along with an amorphous phase as indicated by XRD analysis. The fundamental optical absorption edge and reflection spectra of as-prepared and annealed films are determined. Optical interband transitions are observed for various films (as-prepared and annealed). The presence of crystalline Bi2Te3 in films annealed at 220 °C is also supported by the reflection spectrum. The optical energy gap (Eg), the slope parameter (?) of the absorption edge and the tailing parameter (B-1) of the energy band tails are computed from the optical data. The dc electrical conductivity (?dc) of various films is studied in the temperature range of 150-450 K. We observe that two types of conduction take place: conduction through extended states in the higher temperature region, and conduction through localized states in the band tails and at the Fermi level by the hopping process assisted by phonons at lower temperatures. The data at higher temperatures have been fitted with the expression ?dc = ?0exp(-?E/kT) and the electrical parameters, ?E and ?0, are also determined. It is observed that the bismuth concentration and annealing temperature dependences of the optical and electrical parameters are different in the two regions of compositions, x ? 2.93 and x > 2.93, indicating structural differences in the two sets of compositions. It is pointed out that the bulk form of these amorphous semiconductors exhibits a carrier sign reversal at a bismuth concentration of about 3.5 at%. However, the thin-film form of these amorphous semiconductors does not show such a carrier sign reversal in the electrical transport.

  17. Effect of Ti3SiC2 formation on p-type GaN by vacuum annealing on the contact properties

    NASA Astrophysics Data System (ADS)

    Mohd Halil, Aiman bin; Maeda, Masakatsu; Takahashi, Yasuo

    2014-08-01

    In the present study, after the formation of Ti3SiC2 on p-type GaN by depositing Ti- Si-C ternary film with a composition stoichiometrically close to Ti3SiC2 and subsequent annealing at temperatures of 973 K and 1073 K (lower than the annealing temperature for a contact between p-type SiC and Ti3SiC2), the resulting contact properties were analysed by X- ray diffraction, a direct-current conduction test, and a Hall-effect measurement test. The X-ray diffraction results reveal that the Ti3SiC2 phase is successfully formed after the annealing. The direct-current conduction test shows that ohmic-like contacts are achieved after the formation of Ti3SiC2. However, the Hall-effect measurement test reveals that the dominant carrier type of the specimens is inverted from p-type to n-type even after the annealing at 973 K. The N vacancy formation during the annealing is likely the cause of this change. The contact properties of the annealed specimens are discussed because it is difficult to achieve ohmic contact formation between n-type GaN and Ti3SiC2.

  18. Laser-matter interactions, phase changes and diffusion phenomena during laser annealing of plasmonic AlN:Ag templates and their applications in optical encoding

    NASA Astrophysics Data System (ADS)

    Siozios, A.; Koutsogeorgis, D. C.; Lidorikis, E.; Dimitrakopulos, G. P.; Pliatsikas, N.; Vourlias, G.; Kehagias, T.; Komninou, P.; Cranton, W.; Kosmidis, C.; Patsalas, P.

    2015-07-01

    Nanocomposite thin films incorporating silver nanoparticles are emerging as photosensitive templates for optical encoding applications. However, a deep understanding of the fundamental physicochemical mechanisms occurring during laser-matter interactions is still lacking. In this work, the photosensitivity of AlN:Ag plasmonic nanocomposites is thoroughly examined and a series of UV laser annealing parameters, such as wavelength, fluence and the number of pulses are investigated. We report and study effects such as the selective crystallization of the AlN matrix, the enlargement of the Ag nanoparticle inclusions by diffusion of laser-heated Ag and the outdiffusion of Ag to the film’s surface. Detailed optical calculations contribute to the identification and understanding of the aforementioned physical mechanisms and of their dependency on the laser processing parameters. We are then able to predetermine the plasmonic response of processed AlN:Ag nanocomposites and demonstrate its potential by means of optically encoding an overt or covert cryptographic pattern.

  19. Heating steels in vacuum

    Microsoft Academic Search

    Marmer

    1983-01-01

    It is recommended that high-strength and corrosion-resistant steels be heated in an electric vacuum furnace. Absence of oxidation and decarburization, decrease in the deformation of the part, increase in service life, plus safety, and nontoxicity in the shop, are cited as advantages. Annealing, carburizing, hardening, brazing, and sintering--all detailed-can be more efficiently accomplished in vacuum heating. As vacuum heating requires

  20. Depth profile investigation of ?-FeSi2 formed in Si(1 0 0) by high fluence implantation of 50 keV Fe ion and post-thermal vacuum annealing

    NASA Astrophysics Data System (ADS)

    Lakshantha, Wickramaarachchige J.; Kummari, Venkata C.; Reinert, Tilo; McDaniel, Floyd D.; Rout, Bibhudutta

    2014-08-01

    A single phase polycrystalline ?-FeSi2 layer has been synthesized at the near surface region by implantation in Si(1 0 0) of a high fluence (?1017 atoms/cm2) of 50 keV Fe ions and subsequent thermal annealing in vacuum at 800 °C. The depth profile of the implanted Fe atoms in Si(1 0 0) were simulated by the widely used transportation of ions in matter (TRIM) computer code as well as by the dynamic transportation of ions in matter code (T-DYN). The simulated depth profile predictions for this heavy ion implantation process were experimentally verified using Rutherford Backscattering Spectrometry (RBS) and X-ray Photoelectron Spectroscopy (XPS) in combination with Ar-ion etching. The formation of the ?-FeSi2 phase was monitored by X-ray diffraction measurements. The T-DYN simulations show better agreement with the experimental Fe depth profile results than the static TRIM simulations. The experimental and T-DYN simulated results show an asymmetric distribution of Fe concentrated more toward the surface region of the Si substrate.

  1. Effect of annealing on the nanoscratch behavior of multilayer Si 0.8Ge 0.2/Si films

    NASA Astrophysics Data System (ADS)

    Lian, Derming

    2010-11-01

    In this study, we examined the nanoscratch behavior of annealed multilayered silicon-germanium (SiGe) films comprising alternating sublayers (Si) deposited using an ultrahigh-vacuum chemical vapor deposition (UHV/CVD) system. Annealing consisted of ex situ thermal treatment in a furnace system. We used a nanoscratch technique to investigate the nanotribological behavior of the SiGe films and atomic force microscopy (AFM) to observe deformation phenomena. Our AFM morphological studies of the SiGe films revealed that pile-up phenomena occurred on both sides of each scratch. The scratched surfaces of the SiGe films that had been subjected to various annealing conditions exhibited significantly different features, it is conjectured that cracking dominates in the case of SiGe films while ploughing dominates during the scratching process. We obtained higher coefficients of friction ( ?) when the ramped force was set at 6000 ?N, rather than 2000 ?N, suggesting that annealing of SiGe films leads to higher shear resistance; annealing treatment not only produced misfit dislocations in the form of a significantly wavy sliding surface but also promoted scratching resistance.

  2. Vacuum arcs and switching

    Microsoft Academic Search

    G. A. Farrall

    1973-01-01

    This paper is a review of vacuum-arc phenomena which are related to switching devices. Despite the device overtones, the approach adopted for this paper is fundamental. Topics discussed include the drawn arc, the triggered arc, the power input to the cathode spot, cathode-spot division, arc stability, substructure of the cathode spot, dielectric recovery processes, and breakdown between electrodes subjected to

  3. Structure and luminescence of annealed nanoparticles of ZnS:Mn A. D. Dinsmore,a)

    E-print Network

    Dinsmore, Tony

    Structure and luminescence of annealed nanoparticles of ZnS:Mn A. D. Dinsmore,a) D. S. Hsu, S. B Structural and light-emitting properties of nanoparticles of ZnS:Mn annealed in vacuum at temperatures up of some particles without substantial change in the luminescence or ZnS lattice. After annealing at 400

  4. Rapid thermal annealing enhanced crystalline SiC particles at lower formation temperature

    Microsoft Academic Search

    B. H. Wu; C. K. Chung; C. C. Peng

    2008-01-01

    Formation of nanoparticle SiC (np-SiC) from three-layer Si\\/C\\/Si multilayers on Si(100) substrates were investigated using ultra-high-vacuum ion beam sputtering and post annealing by conventional furnace annealing (FA) and rapid thermal annealing (RTA). Fixing the thickness of bottom Si-layer at 50 nm, different thicknessses of the top Si and C layers were designed to study the effect of annealing on the

  5. Post-annealed gallium and aluminum co-doped zinc oxide films applied in organic photovoltaic devices

    PubMed Central

    2014-01-01

    Gallium and aluminum co-doped zinc oxide (GAZO) films were produced by magnetron sputtering. The GAZO films were post-annealed in either vacuum or hydrogen microwave plasma. Vacuum- and hydrogen microwave plasma-annealed GAZO films show different surface morphologies and lattice structures. The surface roughness and the spacing between adjacent (002) planes decrease; grain growth occurs for the GAZO films after vacuum annealing. The surface roughness increases and nanocrystals are grown for the GAZO films after hydrogen microwave plasma annealing. Both vacuum and hydrogen microwave plasma annealing can improve the electrical and optical properties of GAZO films. Hydrogen microwave plasma annealing improves more than vacuum annealing does for GAZO films. An electrical resistivity of 4.7?×?10?4 ?-cm and average optical transmittance in the visible range from 400 to 800 nm of 95% can be obtained for the GAZO films after hydrogen microwave plasma annealing. Hybrid organic photovoltaic (OPV) devices were fabricated on the as-deposited, vacuum-annealed, and hydrogen microwave plasma-annealed GAZO-coated glass substrates. The active layer consisted of blended poly(3-hexylthiophene) (P3HT) and [6,6]-phenyl C61 butyric acid methyl ester (PCBM) in the OPV devices. The power conversion efficiency of the OPV devices is 1.22% for the hydrogen microwave plasma-annealed GAZO films, which is nearly two times higher compared with that for the as-deposited GAZO films. PMID:25352768

  6. Annealing-insensitive "black silicon" with high infrared absorption

    NASA Astrophysics Data System (ADS)

    Peng, Yan; Chen, Xiangqian; Zhou, Yunyan; Xu, Gongjie; Cai, Bin; Zhu, Yiming; Xu, Jian; Henderson, Ron; Dai, Jianming

    2014-08-01

    A black silicon structure with high-aspect-ratio surface spikes was designed and fabricated in vacuum, resulting in absorptance >90% over the range of 200-2500 nm. It is demonstrated that annealing, an essential step in the fabrication of semiconductor devices, has almost no effect on the infrared absorption of this material, while the infrared absorption of an identical structure fabricated in a SF6 drops dramatically after the annealing process. The characteristic of high infrared absorption and annealing-insensitivity is attributed to both the high-aspect-ratio structure and the phosphor-doped low impedance silicon. These results are important for the fabrication of highly efficient optoelectronic devices.

  7. On the Debossing, Annealing and Mounting of Bells

    NASA Astrophysics Data System (ADS)

    PERRIN, R.; SWALLOWE, G. M.; CHARNLEY, T.; MARSHALL, C.

    1999-10-01

    Changes in the frequencies of the musical partials of various types of bells following debossing dismounting/mounting and annealing/quench annealing are reported. Debossing, dismounting and quench annealing lead to frequency drops, while mounting gives rises. Annealing can lead to frequency increases or decreases depending upon the maximum temperature employed and the initial residual stress. Qualitative explanations of these phenomena are given in terms of changes in crown stiffness, internal stress and alloy phase structure. These are supported by the results of X-ray diffraction measurements. Although the effects are all small they can be large enough to be detected by a reasonably musical car. This, together with the fact that the effects cannot be controlled, gives a plausible explanation of why modern bellfounders use vertical lathes for tuning, even with small carillon bells, and do not anneal bells when trying to control warble.

  8. Vanadium transition metal oxide films obtained by annealing under room atmosphere of metal layers sequentially deposited

    Microsoft Academic Search

    E Baba Ali; J. C Bernède; P Le Ray

    2000-01-01

    Metallic thin films M\\/V\\/M\\/V... \\/V\\/M (M=Fe,Ni) sequentially deposited under vacuum were annealed for 12h in room atmosphere. The samples were characterised by X-rays diffraction (XRD), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM) and optical absorption (OA) and near-infrared absorption. The annealing temperature and the substrate were taken as parameters. In addition some pre-annealing treatment was used. The results showed

  9. Annealed single-crystal cadmium selenide electrodes in liquid junction solar cells

    Microsoft Academic Search

    S. Wessel; A. Mackintosh; K. Colbow

    1984-01-01

    I-V characteristics, voltage dependence of the quantum efficiency, and spectral response were compared for annealed single-crystal CdSe photoanodes. Annealing in cadmium atmosphere improved the overall solar response considerably, while annealing under vacuum revealed a poor response for photon energies larger than 1.8 eV and a high quantum efficiency for near-bandgap energies. This behavior may be attributed to electron-hole pair generation

  10. Ultrathin, ultrasmooth, and low-loss silver films via wetting and annealing K. P. Chen,1

    E-print Network

    Shalaev, Vladimir M.

    deposited sequentially on the initial substrates without breaking the chamber vacuum. First, a 10 nm SiO2 demonstrated that a thermal annealing treatment can reduce the optical losses in ultrathin, ultrasmooth, silver thermal annealing treatment to reduce the ultrathin SF losses significantly by enlarging the internal

  11. Vacuum Technology

    SciTech Connect

    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.

  12. Vacuum mechatronics

    NASA Technical Reports Server (NTRS)

    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.

  13. Deterministic annealing EM algorithm

    Microsoft Academic Search

    Naonori Ueda; Ryohei Nakano

    1998-01-01

    Abstract This paper presents a deterministic annealing EM (DAEM) algorithm for maximum,likelihood estimation problems,to overcome,a local maxima problem associated with the conventional EM algorithm. In our approach, a new posterior parameterized by ‘temperature’ is derived by using the principle of maximum entropy and is used for controlling the annealing process. In the DAEM algorithm, the EM process is reformulated as

  14. A high-vacuum multichamber tester for specimens and materials

    Microsoft Academic Search

    G. G. Maksiraovich; V. S. Baranen'kii; S. M. Kuplak; V. S. Pavlina; V. N. Vinogradov; B. M. Stakhnyak; V. S. Ribal'chenko

    1992-01-01

    Working principles are described for a high-vacuum multichamber tester that provides four simultaneously operating vacuum chambers in which various thermal operations can be performed: annealing, life test with thermal stabilization, thermal cycling, effects of temperature and residual gases on the corrosion and physical properties of constructional materials, etc. Ongoing observations can be made on the specimen resistance. A feature is

  15. GenAnneal: Genetically modified Simulated Annealing

    NASA Astrophysics Data System (ADS)

    Tsoulos, Ioannis G.; Lagaris, Isaac E.

    2006-05-01

    A modification of the standard Simulated Annealing (SA) algorithm is presented for finding the global minimum of a continuous multidimensional, multimodal function. We report results of computational experiments with a set of test functions and we compare to methods of similar structure. The accompanying software accepts objective functions coded both in Fortran 77 and C++. Program summaryTitle of program:GenAnneal Catalogue identifier:ADXI_v1_0 Program summary URL:http://cpc.cs.qub.ac.uk/summaries/ADXI_v1_0 Program available from: CPC Program Library, Queen's University of Belfast, N. Ireland Computer for which the program is designed and others on which it has been tested: The tool is designed to be portable in all systems running the GNU C++ compiler Installation: University of Ioannina, Greece on Linux based machines Programming language used:GNU-C++, GNU-C, GNU Fortran 77 Memory required to execute with typical data: 200 KB No. of bits in a word: 32 No. of processors used: 1 Has the code been vectorized or parallelized?: No No. of bytes in distributed program, including test data, etc.:84 885 No. of lines in distributed program, including test data, etc.:14 896 Distribution format: tar.gz Nature of physical problem: A multitude of problems in science and engineering are often reduced to minimizing a function of many variables. There are instances that a local optimum does not correspond to the desired physical solution and hence the search for a better solution is required. Local optimization techniques are frequently trapped in local minima. Global optimization is hence the appropriate tool. For example, solving a non-linear system of equations via optimization, employing a "least squares" type of objective, one may encounter many local minima that do not correspond to solutions (i.e. they are far from zero). Typical running time: Depending on the objective function. Method of solution: We modified the process of step selection that the traditional Simulated Annealing employs and instead we used a global technique based on grammatical evolution.

  16. Quo Vadis quantum annealing?

    NASA Astrophysics Data System (ADS)

    Das, Arnab; Suzuki, Sei

    2015-02-01

    In this article we sketch a broad outline of quantum annealing as a framework for realizing analog quantum computation. We provide a short review of the basic ideas and discuss some issues relevant to the current scenario of condensed matter physics and quantum computation.

  17. Placement by thermodynamic simulated annealing

    Microsoft Academic Search

    Juan de Vicente; Juan Lanchares; Román Hermida

    2003-01-01

    Combinatorial optimization problems arise in different fields of science and engineering. There exist some general techniques coping with these problems such as simulated annealing (SA). In spite of SA success, it usually requires costly experimental studies in fine tuning the most suitable annealing schedule. In this Letter, the classical integrated circuit placement problem is faced by Thermodynamic Simulated Annealing (TSA).

  18. Effect of Zone Drawing, Zone Annealing and Annealing at Constant Length on the Structure and Mechanical Properties of Biends of PET, PBT and Polyamide 6

    Microsoft Academic Search

    M. Evstatiev; A. A. Apostolov; S. Fakirov

    1999-01-01

    Binary (1:1 by wt.) and ternary (1:1:1 by wt.) blends of polyethylene terephthalate, poly(butylene terephthalate) and polyamide-6 were extruded as strips and ultraquenched from the melt. After zone drawing and subsequent zone annealing or annealing at constant length at temperature T = 220°C for 5 hours in vacuum, the samples were studied by differential scanning calorimetry, wide-angle X-ray scattering, small-angle

  19. Morphological variations in AuxSiy nanostructures under variable pressure and annealing conditions

    NASA Astrophysics Data System (ADS)

    Rath, A.; Dash, J. K.; Juluri, R. R.; Satyam, P. V.

    2015-03-01

    Well-ordered, substrate symmetry-driven, AuxSiy structures of average size ~25 nm were formed under ultra-high vacuum (UHV) conditions using molecular beam epitaxy method. Post-annealing was done at 500 °C in three different vacuum conditions: (1) low vacuum (LV) (10-2 mbar), (2) high vacuum (HV) (10-5 mbar) and (3) UHV (10-10 mbar) (MBE chamber). For both HV and LV cases, the AuxSiy nanostructures were found to have their corners rounded unlike in UHV case where the structures have sharp edges. In all the above three cases, samples were exposed to air before annealing. In situ annealing inside UHV chamber without exposing to air resulted in well-aligned rectangles with sharp corners, while sharp but irregular island structures were found for air exposed and UHV annealing system. The role of residual gases present in LV and HV annealing environment and inhibition of lateral surface diffusion due to the presence of surface oxide (through air exposure) would be discussed. Annealing at various conditions yielded variation in the coverage and correspondingly, the average area of nanostructures varied from a ~329 nm2 (as deposited) to ~2,578 nm2 (at high temperature). High-resolution transmission electron microscopy (planar and cross section) has been utilized to study the morphological variations.

  20. Annealing Effects on Transition Temperature of Superconductiong Bi-Sr-Ca-Cu-O Films after Ion Irradiation

    Microsoft Academic Search

    Taiji Hoshiya; Saburo Takamura; Takeo Aruga; Mamoru Kobiyama

    1989-01-01

    The effect of annealing after irradiation on the transition temperature is studied for polycrystalline Bi-Sr-Ca-Cu-O films irradiated by He ions at room temperature. The temperatures of the out-diffusion and the in-diffusion of oxygen are obtained by annealing in air and a vacuum. There is a large recovery stage around 200˜ 500°C on annealing in air after irradiation. The 110 K

  1. Vacuum Technology: Vacuum Technology III

    NSDL National Science Digital Library

    Rack, Philip D.

    This is a link to a PDF version of lecture slides that discuss gas sources in a vacuum. The presentation explains concepts such as vapor pressure curves, thermal desorption and first and second order desorption. Keywords: Vaporization, desorption, diffusion, permeation, backstreaming

  2. Electron-irradiation enhanced photoluminescence from GaInNAs\\/GaAs quantum wells subject to thermal annealing

    Microsoft Academic Search

    E.-M. Pavelescu; A. Gheorghiu; M. Dumitrescu; A. Tukiainen; T. Jouhti; T. Hakkarainen; R. Kudrawiec; J. Andrzejewski; J. Misiewicz; N. Tkachenko; H. Lemmetyinen; M. Pessa

    2004-01-01

    Electron irradiation of a 1.3-mum-GaInNAs\\/GaAs multi-quantum-well heterostructure, grown by molecular beam epitaxy and subsequently rapid-thermal annealed, is found to induce much stronger photoluminescence than what is observed for an identical as-grown sample upon annealing. Annealing of the irradiated sample also causes a small additional spectral blueshift and reduces alloy potential energy fluctuations at the conduction band minimum. These irradiation-related phenomena

  3. Extinction of ferromagnetism in HOPG by thermal annealing

    NASA Astrophysics Data System (ADS)

    Miao, Xiaochang; Hebard, Arthur; Tongay, Sefaattin; Appleton, Bill

    2011-03-01

    Observations of ferromagnetism (FM) in highly ordered pyrolytic graphite (HOPG) have generated vigorous research activity to clarify its origin, especially when transition metals are known to be absent. We report that the ferromagnetism of pristine HOPG samples as measured by hysteretic magnetization loops can be diminished and eventually extinguished with sufficiently long high vacuum anneals at temperatures greater than 2000°C. Concomitant with the extinction of ferromagnetism, we observe an anneal-induced increase in grain size (accompanied by possible edge reconstruction) confirmed by XRD measurement and improved transport properties, including lower in-plane and out-of-plane resistance, higher electron and hole mobility and improved charge compensation. The implied anneal-induced reduction of defects and vacancies suggests that the FM of pristine HOPG is correlated with localized states located at zigzag edges, vacancies and related defects. Work supported ONR-00075094 and NSF-1005301.

  4. Rapid preparation of solution-processed InGaZnO thin films by microwave annealing and photoirradiation

    NASA Astrophysics Data System (ADS)

    Cheong, Heajeong; Ogura, Shintaro; Ushijima, Hirobumi; Yoshida, Manabu; Fukuda, Nobuko; Uemura, Sei

    2015-06-01

    We fabricated solution-processed indium-gallium-zinc oxide (IGZO) thin-film transistors (TFTs) by microwave (MW) annealing an IGZO precursor film followed by irradiating with vacuum ultraviolet (VUV) light. MW annealing allows more rapid heating of the precursor film than conventional annealing processes using a hot plate or electric oven and promotes the crystallization of IGZO. VUV irradiation was used to reduce the duration and temperature of the post-annealing step. Consequently, the IGZO TFTs fabricated through MW annealing for 5 min and VUV irradiation for 1 min exhibited an on/off current ratio of 108 and a field-effect mobility of 0.3 cm2 V-1 s-1. These results indicate that MW annealing and photoirradiation is an effective combination for annealing solution processed IGZO precursor films to prepare the semiconductor layers of TFTs.

  5. Oxidation of Ta diffusion barrier layer for Cu metallization in thermal annealing

    Microsoft Academic Search

    Kai-Min Yin; Li Chang; Fu-Rong Chen; Ji-Jung Kai; Cheng-Cheng Chiang; Graham Chuang; Peijun Ding; Barry Chin; Hong Zhang; Fusen Chen

    2001-01-01

    This work examines the thermal stability of Ta barrier layer for Cu metallization with the effect of oxygen. The Cu\\/Ta\\/SiO2\\/Si films were annealed at temperatures ranging from 400 to 600°C under various vacuum conditions. Transmission electron microscopy has been performed to characterize the microstructure of the films after annealing. The results show that an amorphous interlayer of oxide between Cu

  6. Annealing of GaAs solar cells damaged by electron irradiation

    Microsoft Academic Search

    G. H. Walker; E. J. Conway

    1978-01-01

    Measurements of thermal annealing of GaAlAs\\/GaAs solar cells damaged by 1 MeV electron irradiation are reported, and the magnitude of the short-circuit current recovery is discussed. The damaged cells are annealed in a vacuum at 200 C. A cell irradiated at 10 to the 13th power electrons per sq cm recovers all its lost short-circuit current after 15 hours of

  7. Reduced noise in NbN hot-electron bolometer mixers by annealing

    Microsoft Academic Search

    Z. Q. Yang; M. Hajenius; J. J. A. Baselmans; J. R. Gao; B. Voronov; G N Gol’tsman

    2006-01-01

    We find that the sensitivity of heterodyne receivers based on superconducting hot-electron bolometers (HEBs) increases by 25–30% after annealing at 85 °C in vacuum. The devices studied are twin-slot antenna coupled mixers with a small NbN bridge of 1 × 0.15 µm2. We show that annealing changes the device properties as reflected in sharper resistive transitions of the complete device,

  8. RAPID COMMUNICATION: Reduced noise in NbN hot-electron bolometer mixers by annealing

    Microsoft Academic Search

    Z. Q. Yang; M. Hajenius; J. J. A. Baselmans; J. R. Gao; B. Voronov; G. N. Gol'tsman

    2006-01-01

    We find that the sensitivity of heterodyne receivers based on superconducting hot-electron bolometers (HEBs) increases by 25-30% after annealing at 85 °C in vacuum. The devices studied are twin-slot antenna coupled mixers with a small NbN bridge of 1 × 0.15 µm2. We show that annealing changes the device properties as reflected in sharper resistive transitions of the complete device,

  9. Effect of annealing treatment on surface state and subsequent corrosion of 304L stainless steel

    Microsoft Academic Search

    Weirick

    1973-01-01

    Experience with porous flow-control media of 304L stainless steel (SS) has suggested that it may be the annealing process during production that affects the corrosion resistance of the material. To examine this question, test specimens were cut from SS sheet; some were left with the naturally formed oxide surface film, while others were polished. One set was vacuum-annealed at various

  10. STIS CCD Hot Pixel Annealing

    NASA Astrophysics Data System (ADS)

    Hernandez, Svea

    2013-10-01

    This purpose of this activity is to repair radiation induced hot pixel damage to theSTIS CCD by warming the CCD to the ambient instrument temperature and annealing radiation damaged pixels. Radiation damage creates hot pixels in the STIS CCD Detector. Many of these hot pixels can be repaired by warming the CCD from its normal operating temperature near-83 C to the ambient instrument temperature { +5 C} for several hours. The number of hot pixels repaired is a function of annealing temperature. The effectiveness of the CCD hot pixel annealing process is assessed by measuring the dark current behavior before and after annealing and by searching for any window contamination effects.

  11. Silicon carbide formation by annealing C60 films on silicon D. C. Lorents, R. Malhotra, and R. S. Ruoff

    E-print Network

    were then introduced to the high vacuum HV chamber within a few minutes. C60 films 200­300 nm thick2 pieces, and annealed in a separate ultrahigh vacuum UHV chamber (P 10 8 Torr). To pre- vent loss as a semiconductor, high thermal conductivity, chemical inertness, hardness, and wear resistance .1­4 Different

  12. X-Ray Photoelectron Spectroscopy and Tribology Studies of Annealed Fullerene-like WS2 Nanoparticles

    NASA Astrophysics Data System (ADS)

    Kopnov, F.; Tenne, R.; Späth, B.; Jägermann, W.; Cohen, H.; Feldman, Y.; Zak, A.; Moshkovich, A.; Rapoport, L.

    The temporal chemical changes occurring at the surface of fullerene-like (IF) nanoparticles of WS2 were investigated using X-ray photo-electron spectroscopy (XPS) and compared to those of bulk powder (2H) of the same material. It is possible to follow the long term (surface oxidation and carbonization) occurring at defects on the outermost surface (0001) layer of the fullerene-like nanoparticles. Similar but perhaps more distinctive changes are observed on the prismatic (hk0) surfaces of the 2H powder. Vacuum annealing is shown to remove most of these changes and bring the surface close to its stoichiometric composition. In accordance with previous measurements, further evidence is obtained for the existence of water molecules which are entrapped in the hollow core and interstitial defects of the fullerene-like nanoparticles during the synthesis. They are also shown to be removed by the vacuum annealing process. Chemically resolved electrical measurements (CREM) in the XPS show that the vacuum annealed IF samples become more intrinsic. Finally, tribological measurements show that the vacuum annealed IF samples perform better as an additive to oil than the non-annealed IF samples and the bulk (2H) platelets powder.

  13. Development of a vacuum arc fault-current limiter

    NASA Astrophysics Data System (ADS)

    Dollinger, R.; Gilmour, A. S., Jr.

    1981-07-01

    The operating principles of vacuum arc devices for fault current limiting applications are investigated. The general operating characteristics are given for two basic vacuum arc devices. One is the vacuum arc fault current limiter and the other is the magnetically controlled vacuum arc switch. Detailed studies of the phenomena occurring with the two devices are described. In particular, the repetitive voltage spiking phenomena that occurs in the vacuum arc fault current limiter is treated in substantial detail. The mechanism of the voltage spiking (the repetitive formation and collapse of an anode sheath) is described along with measurements that were made of parameters associated with repetitive spiking. Techniques for enhancing current limiting by enhancing spiking development are discussed. Work on the magnetically controlled vacuum arc switch and the cooperative efforts with the industrial partner are described.

  14. Annealing of indium sulfide thin films prepared at low temperature by modulated flux deposition

    NASA Astrophysics Data System (ADS)

    Sanz, C.; Guillén, C.; Herrero, J.

    2013-01-01

    A set of 130 nm thick indium sulfide films was deposited on soda-lime glass substrates at 150 °C by modulated flux deposition (MFD). Next, four different annealing conditions were carried out inside the MFD equipment, namely annealings with and without additional delivery of sulfur were investigated at two annealing temperatures, TA = 250 °C and TA = 350 °C. All the annealing conditions enhanced the crystallinity of the as-deposited indium sulfide films, which was considered as the main factor after the increase of the optical transmission, on the bandgap energy (Eg) and on the electrical conductivity. Eg increased from 2.62 eV for the as-deposited films to 2.66 eV (TA = 250 °C) and 2.73 eV (TA = 350 °C). Regarding the electrical properties, a minimum resistivity of 4.8 ? cm was achieved by vacuum-annealing at 350 °C without the delivery of sulfur.

  15. Annealing to Mitigate Pitting in Electropolished Niobium Coupons and SRF Cavities

    SciTech Connect

    Cooley, L.D.; Hahn, E.; Hicks, D.; Romanenko, A.; Schuessler, R.; Thompson, C.; /Fermilab

    2011-06-08

    Ongoing studies at Fermilab investigate whether dislocations and other factors instigate pitting during cavity electropolishing (EP), despite careful processing controls and the inherent leveling mechanism of EP itself. Here, cold-worked niobium coupons, which exhibited increased tendencies for pitting in our past study, were annealed in a high vacuum furnace and subsequently processed by EP. Laser confocal scanning microscopy and special defect counting algorithms were used to assess the population of pits formed. Hardness measurements indicated that annealing for 2 hours at 800 C produced recovery, whereas annealing for 12 hours at 600 C did not, as is consistent with known changes for cavities annealed in a similar way. The 800 C anneal was effective in some cases but not others, and we discuss reasons why tendencies for pitting remain. We discuss implications for cavities and continued work to understand pitting.

  16. Effect of post-deposition annealing on the structural, optical and electrical properties of IGZO films

    NASA Astrophysics Data System (ADS)

    Jeon, Jae-Hyun; Gong, Tae-Kyung; Kong, Young-Min; Lee, Hak Min; Kim, Daeil

    2015-05-01

    IGZO thin films were deposited on glass substrates via RF magnetron co-sputtering with In2O3 and GZO targets. The films were then vacuum annealed at 100°C, 200°C and 300°C for 30 minutes to investigate the effects of the annealing temperature on the structural, electrical, and optical properties of the films. Although XRD patterns demonstrated that all films had an amorphous phase regardless of annealing temperature, electrical resistivity decreased to as low as 3.2 × 10-4 ? cm at an annealing temperature of 300°C. The optical transmittance in the visible wavelength region also improved from 80 to 83%. The figure of merit shows that IGZO films annealed at 300°C have the higher optical and electrical performance than other films prepared under different conditions in this study. [Figure not available: see fulltext.

  17. State of the theory of vacuum arcs

    Microsoft Academic Search

    Isak I. Beilis

    2001-01-01

    A review of vacuum arc phenomena including the cathode and anode processes with cold and hot electrodes as well as the processes in the interelectrode plasma is presented. In the case of cold electrodes, the current continuity mechanism, the nature of mass loss, spot motion, plasma jet generation in the spots, and the cathode potential drop are reviewed. The explosive

  18. Vacuum energy and the cosmological constant

    NASA Astrophysics Data System (ADS)

    Bass, Steven D.

    2015-06-01

    The accelerating expansion of the Universe points to a small positive value for the cosmological constant or vacuum energy density. We discuss recent ideas that the cosmological constant plus Large Hadron Collider (LHC) results might hint at critical phenomena near the Planck scale.

  19. Recent advances in vacuum sciences and applications

    NASA Astrophysics Data System (ADS)

    Mozeti?, M.; Ostrikov, K.; Ruzic, D. N.; Curreli, D.; Cvelbar, U.; Vesel, A.; Primc, G.; Leisch, M.; Jousten, K.; Malyshev, O. B.; Hendricks, J. H.; Kövér, L.; Tagliaferro, A.; Conde, O.; Silvestre, A. J.; Giapintzakis, J.; Buljan, M.; Radi?, N.; Draži?, G.; Bernstorff, S.; Biederman, H.; Kylián, O.; Hanuš, J.; Miloševi?, S.; Galtayries, A.; Dietrich, P.; Unger, W.; Lehocky, M.; Sedlarik, V.; Stana-Kleinschek, K.; Drmota-Petri?, A.; Pireaux, J. J.; Rogers, J. W.; Anderle, M.

    2014-04-01

    Recent advances in vacuum sciences and applications are reviewed. Novel optical interferometer cavity devices enable pressure measurements with ppm accuracy. The innovative dynamic vacuum standard allows for pressure measurements with temporal resolution of 2 ms. Vacuum issues in the construction of huge ultra-high vacuum devices worldwide are reviewed. Recent advances in surface science and thin films include new phenomena observed in electron transport near solid surfaces as well as novel results on the properties of carbon nanomaterials. Precise techniques for surface and thin-film characterization have been applied in the conservation technology of cultural heritage objects and recent advances in the characterization of biointerfaces are presented. The combination of various vacuum and atmospheric-pressure techniques enables an insight into the complex phenomena of protein and other biomolecule conformations on solid surfaces. Studying these phenomena at solid-liquid interfaces is regarded as the main issue in the development of alternative techniques for drug delivery, tissue engineering and thus the development of innovative techniques for curing cancer and cardiovascular diseases. A review on recent advances in plasma medicine is presented as well as novel hypotheses on cell apoptosis upon treatment with gaseous plasma. Finally, recent advances in plasma nanoscience are illustrated with several examples and a roadmap for future activities is presented.

  20. Simulated annealing algorithms: an overview

    Microsoft Academic Search

    Rob A. Rutenbar

    1989-01-01

    A brief introduction is given to the actual mechanics of simulated annealing, and a simple example from an IC layout is used to illustrate how these ideas can be applied. The complexities and tradeoffs involved in attacking a realistically complex design problem are illustrated by dissecting two very different annealing algorithms for VLSI chip floorplanning. Several current research problems aimed

  1. Wear of Steel and Ti6Al4V Rollers in Vacuum

    NASA Technical Reports Server (NTRS)

    Krantz, Timothy L.; Shareef, Iqbal

    2012-01-01

    This investigation was prompted by results of a qualification test of a mechanism to be used for the James Webb Space Telescope. Post-test inspections of the qualification test article revealed some loose wear debris and wear of the steel rollers and the mating Ti6Al4V surfaces. An engineering assessment of the design and observations from the tested qualification unit suggested that roller misalignment was a controlling factor. The wear phenomena were investigated using dedicated laboratory experiments. Tests were done using a vacuum roller rig for a range of roller misalignment angles. The wear in these tests was mainly adhesive wear. The measured wear rates were highly correlated to the misalignment angle. For all tests with some roller misalignment, the steel rollers lost mass while the titanium rollers gained mass indicating strong adhesion of the steel with the titanium alloy. Inspection of the rollers revealed that the adhesive wear was a two-way process as titanium alloy was found on the steel rollers and vice versa. The qualification test unit made use of 440F steel rollers in the annealed condition. Both annealed 440F steel rollers and hardened 440C rollers were tested in the vacuum roller rig to investigate possibility to reduce wear rates and the risk of loose debris formation. The 440F and 440C rollers had differing wear behaviors with significantly lesser wear rates for the 440C. For the test condition of zero roller misalignment, the adhesive wear rates were very low, but still some loose debris was formed

  2. Science and Paranormal Phenomena

    SciTech Connect

    Noyes, H. Pierre

    1999-06-03

    In order to ground my approach to the study of paranormal phenomena, I first explain my operational approach to physics, and to the ''historical'' sciences of cosmic, biological, human, social and political evolution. I then indicate why I believe that ''paranormal phenomena'' might-but need not- fit into this framework. I endorse the need for a new theoretical framework for the investigation of this field presented by Etter and Shoup at this meeting. I close with a short discussion of Ted Bastin's contention that paranormal phenomena should be defined as contradicting physics.

  3. Science and Paranormal Phenomena

    E-print Network

    Noyes, H P

    1999-01-01

    In order to ground my approach to the study of paranormal phenomena, I first explain my operational approach to physics, and to the ``historical'' sciences of cosmic, biological, human, social and political evolution. I then indicate why I believe that ``paranormal phenomena'' might --- but need not --- fit into this framework. I endorse the need for a new theoretical framework for the investigation of this field presented by Etter and Shoup at this meeting. I close with a short discussion of Ted Bastin's contention that paranormal phenomena should be {\\it defined} as contradicting physics.

  4. Science and Paranormal Phenomena

    E-print Network

    H. Pierre Noyes

    1999-06-03

    In order to ground my approach to the study of paranormal phenomena, I first explain my operational approach to physics, and to the ``historical'' sciences of cosmic, biological, human, social and political evolution. I then indicate why I believe that ``paranormal phenomena'' might --- but need not --- fit into this framework. I endorse the need for a new theoretical framework for the investigation of this field presented by Etter and Shoup at this meeting. I close with a short discussion of Ted Bastin's contention that paranormal phenomena should be {\\it defined} as contradicting physics.

  5. The effect of post oxide deposition annealing on the effective work function in metal/Al2O3/InGaAs gate stack

    NASA Astrophysics Data System (ADS)

    Winter, R.; Krylov, I.; Ahn, J.; McIntyre, P. C.; Eizenberg, M.

    2014-05-01

    The effect of post oxide deposition annealing on the effective work function in metal/Al2O3/ InGaAs gate stacks was investigated. Using a systematic method for effective work function extraction, a shift of 0.3 ± 0.1 eV was found between the effective work function of forming gas annealed samples and vacuum annealed samples. The electrical measurements enabled us to obtain the band alignment of the metal/Al2O3/InGaAs gate stack. This band alignment was confirmed by X-ray photoelectron spectroscopy. The measured shift in the effective work function between different annealing ambient may be attributed to indium out-diffusion during post oxide deposition annealing that is observed in forming gas anneal to a much larger extent than in vacuum.

  6. Fullerene formation and annealing

    SciTech Connect

    Mintmire, J.W. [Naval Research Lab., Washington, DC (United States)

    1996-04-05

    Why does the highly symmetric carbon cluster C{sub 60} form in such profusion under the right conditions? This question was first asked in 1985, when Kroto suggested that the predominance of the C{sub 60} carbon clusters observed in the molecular beam experiments could be explained by the truncated icosahedral (or soccer ball) form. The name given to this cluster, buckminsterfullerene, led to the use of the term fullerenes for the family of hollow-cage carbon clusters made up of even numbers of triply coordinated carbons arranged with 12 pentagonal rings and an almost arbitrary number of hexagonal rings. More than a decade later, we still lack a completely satisfying understanding of the fundamental chemistry that takes place during fullerene formation. Most current models for fullerene formation require a facile mechanism for ring rearrangement in the fullerene structure, but the simplest proposed mechanisms are believed to have unrealistically high activation barriers. In recent research calculations have suggested that atomic carbon in the reaction mixture could act as a catalyst and allow substantially lower activation barriers for fullerene annealing. This article discusses the background for this research and other adjunct research. 14 refs.

  7. Study on effect of annealing conditions on structural, magnetic and superconducting properties of MgB{sub 2} bulk samples

    SciTech Connect

    Phaneendra, Konduru, E-mail: phaneendra-50@yahoo.com; Asokan, K., E-mail: phaneendra-50@yahoo.com; Kanjilal, D. [Inter University Accelerator Centre, Aruna Asaf Ali Marg, Vasanth Kung, New Delhi-110067 (India); Awana, V. P. S. [Quantum Phenomena and Applications, National Physical Laboratory, K S Krishnan Marg, New Delhi-110012 (India); Sastry, S. Sreehari [Dept. of Physics, Acharya Nagarjuna University, Guntur-522510 (India)

    2014-04-24

    Effect of annealing conditions on structural, magnetic and superconducting properties of Magnesium Diboride (MgB{sub 2}) bulk superconductor samples prepared by solid state route method are compared. The samples are made by taking Magnesium and Boron powders in stoichiometric ratio, grounded well and pelletized at pressure of about 10Tonnes. These pellets are annealed in both Argon and vacuum environment separately up to 800°c for two hours. Both the samples show clear superconducting transition at Tc ? 38 k. This is further conformed by AC/DC magnetization (M-T), Resistivity [? (T, H)] measurements under magnetic field up to 14 Tesla as well. Rietveld refinement of X-ray diffraction of both samples conformed the MgB{sub 2} phase formation with P6/mmm space group symmetry. Scanning Electron Microscopy images of the surface revile more agglomeration of grains in case of Argon annealed samples. This result in more critical current density (J{sub c}) of Argon annealed samples than vacuum annealed one calculated from Bean's critical state model. This high Jc is explained in terms of more inter grain connectivity for Argon annealed sample than vacuum annealed sample.

  8. Reversibility of trapped hole annealing

    Microsoft Academic Search

    A. J. Lelis; H. E. Jr. Boesch; T. R. Oldham; F. B. McLean

    1988-01-01

    Annealing under negative bias of metal-oxide semiconductor field-effect transistors (MOSFETs) previously irradiated and annealed under positive bias is studied as a function of oxide field and time. Using three different sets of samples ranging from hard to soft, the authors have observed a considerable reversal of the oxide trapped charge component, ..delta..V\\/sub ot\\/, in the two harder sets and essentially

  9. Laser sealed vacuum insulating window

    DOEpatents

    Benson, D.K.; Tracy, C.E.

    1985-08-19

    A laser sealed evacuated window panel is comprised of two glass panes held spaced apart in relation to each other by a plurality of spherical glass beads and glass welded around the edges to provide an evacuated space between the glass panes that is completely glass sealed from the exterior. The glass welded edge seal is obtained by welding the edges of the glass panes together with a laser beam while the glass panes and bead spacers are positioned in a vacuum furnace and heated to the annealing point of the glass to avoid stress fracture in the area of the glass weld. The laser welding in the furnace can be directed around the perimeter of the galss panel by a combination of rotating the glass panel and linearly translating or aiming the laser with a relay mirror.

  10. Annealing to Mitigate Pitting in Electropolished Niobium Coupons and SRF Cavities

    Microsoft Academic Search

    L. D. Cooley; E. Hahn; D. Hicks; A. Romanenko; R. Schuessler; C. Thompson

    2011-01-01

    Ongoing studies at Fermilab investigate whether dislocations and other factors instigate pitting during cavity electropolishing (EP), despite careful processing controls and the inherent leveling mechanism of EP itself. Here, cold-worked niobium coupons, which exhibited increased tendencies for pitting in our past study, were annealed in a high vacuum furnace and subsequently processed by EP. Laser confocal scanning microscopy and special

  11. Vacuum polarization and Hawking radiation

    NASA Astrophysics Data System (ADS)

    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.

  12. Inhomogeneous vacuum energy

    NASA Astrophysics Data System (ADS)

    Wands, David; De-Santiago, Josue; Wang, Yuting

    2012-07-01

    Vacuum energy remains the simplest model of dark energy which could drive the accelerated expansion of the Universe without necessarily introducing any new degrees of freedom. Inhomogeneous vacuum energy is necessarily interacting in general relativity. Although the 4-velocity of vacuum energy is undefined, an interacting vacuum has an energy transfer and the vacuum energy defines a particular foliation of spacetime. In particular we will discuss cosmological solutions where the background vacuum energy is spatially homogeneous. It is possible to give a consistent description of vacuum dynamics and in particular the relativistic equations of motion for spatially inhomogeneous perturbations given a covariant prescription for the vacuum energy, or equivalently the energy transfer 4-vector, and we construct gauge-invariant vacuum perturbations. We show that any dark energy cosmology can be decomposed into an interacting vacuum+matter cosmology whose inhomogeneous perturbations obey simple first-order equations.

  13. Indium out-diffusion in Al{sub 2}O{sub 3}/InGaAs stacks during anneal at different ambient conditions

    SciTech Connect

    Krylov, Igor, E-mail: krylov@tx.technion.ac.il [The Russell Berrie Nanotechnology Institute, Technion–Israel Institute of Technology, Haifa 32000 (Israel); Winter, Roy [Department of Materials Science and Engineering, Technion–Israel Institute of Technology, Haifa 32000 (Israel); Ritter, Dan [The Russell Berrie Nanotechnology Institute, Technion–Israel Institute of Technology, Haifa 32000 (Israel); Department of Electrical Engineering, Technion–Israel Institute of Technology, Haifa 32000 (Israel); Eizenberg, Moshe [The Russell Berrie Nanotechnology Institute, Technion–Israel Institute of Technology, Haifa 32000 (Israel); Department of Materials Science and Engineering, Technion–Israel Institute of Technology, Haifa 32000 (Israel)

    2014-06-16

    Indium out-diffusion during anneal enhances leakage currents in metal/dielectric/InGaAs gate stacks. In this work, we study the influence of ambient conditions during anneal on indium out-diffusion in Al{sub 2}O{sub 3}/InGaAs structures, prior to the gate metal deposition. Using X-ray photoemission spectroscopy and time of flight secondary ions mass spectrometry, we observed much lower indium concentrations in the Al{sub 2}O{sub 3} layer following vacuum and O{sub 2} anneals compared to forming gas or nitrogen anneals. The electrical characteristics of the Ni/Al{sub 2}O{sub 3}/InGaAs gate stack following these pre-metallization anneals as well as after subsequent post metallization anneals are presented. Possible explanations for the role of the annealing ambient conditions on indium out-diffusion are presented.

  14. Germanium detector vacuum encapsulation

    NASA Technical Reports Server (NTRS)

    Madden, N. W.; Malone, D. F.; Pehl, R. H.; Cork, C. P.; Luke, P. N.; Landis, D. A.; Pollard, M. J.

    1991-01-01

    This paper describes an encapsulation technology that should significantly improve the viability of germanium gamma-ray detectors for a number of important applications. A specialized vacuum chamber has been constructed in which the detector and the encapsulating module are processed in high vacuum. Very high vacuum conductance is achieved within the valveless encapsulating module. The detector module is then sealed without breaking the chamber vacuum. The details of the vacuum chamber, valveless module, processing, and sealing method are presented.

  15. Germanium detector vacuum encapsulation

    NASA Astrophysics Data System (ADS)

    Madden, N. W.; Malone, D. F.; Pehl, R. H.; Cork, C. P.; Luke, P. N.; Landis, D. A.; Pollard, M. J.

    1991-08-01

    This paper describes an encapsulation technology that should significantly improve the viability of germanium gamma-ray detectors for a number of important applications. A specialized vacuum chamber has been constructed in which the detector and the encapsulating module are processed in high vacuum. Very high vacuum conductance is achieved within the valveless encapsulating module. The detector module is then sealed without breaking the chamber vacuum. The details of the vacuum chamber, valveless module, processing, and sealing method are presented.

  16. Stress pulse phenomena

    SciTech Connect

    McGlaun, M.

    1993-08-01

    This paper is an introductory discussion of stress pulse phenomena in simple solids and fluids. Stress pulse phenomena is a very rich and complex field that has been studied by many scientists and engineers. This paper describes the behavior of stress pulses in idealized materials. Inviscid fluids and simple solids are realistic enough to illustrate the basic behavior of stress pulses. Sections 2 through 8 deal with the behavior of pressure pulses. Pressure is best thought of as the average stress at a point. Section 9 deals with shear stresses which are most important in studying solids.

  17. Atomic-scale investigation of graphene grown on Cu foil and the effects of thermal annealing.

    PubMed

    Cho, Jongweon; Gao, Li; Tian, Jifa; Cao, Helin; Wu, Wei; Yu, Qingkai; Yitamben, Esmeralda N; Fisher, Brandon; Guest, Jeffrey R; Chen, Yong P; Guisinger, Nathan P

    2011-05-24

    We have investigated the effects of thermal annealing on ex-situ chemically vapor deposited submonolayer graphene islands on polycrystalline Cu foil at the atomic-scale using ultrahigh vacuum scanning tunneling microscopy. Low-temperature annealed graphene islands on Cu foil (at ?430 °C) exhibit predominantly striped Moire? patterns, indicating a relatively weak interaction between graphene and the underlying polycrystalline Cu foil. Rapid high-temperature annealing of the sample (at 700-800 °C) gives rise to the removal of Cu oxide and the recovery of crystallographic features of the copper that surrounds the intact graphene. These experimental observations of continuous crystalline features between the underlying copper (beneath the graphene islands) and the surrounding exposed copper areas revealed by high-temperature annealing demonstrates the impenetrable nature of graphene and its potential application as a protective layer against corrosion. PMID:21500843

  18. Annealing and Test Temperature Dependence of Tensile Properties of UNS N04400 Alloy

    NASA Astrophysics Data System (ADS)

    Afzal, Naveed; Ahmad, R.; Akhtar, Tanveer; Ayub, R.; Ghauri, I. M.

    2013-07-01

    Effects of annealing and test temperatures on the tensile behavior of UNS N04400 alloy have been examined. The specimens were annealed at 800, 1000, and 1200 °C for 4 h under vacuum in a muffle furnace. Stress-strain curves of the specimens were obtained in the temperature range 25-300 °C using a universal testing machine fitted with a thermostatic chamber. The results indicate that the yield strength (YS), ultimate tensile strength (UTS), and percentage elongation of the specimens decrease with increase of annealing temperature. By increasing the test temperature, the YS and UTS decrease, whereas the percentage elongation initially decreases with increase of test temperature from 25 to 100 °C and then increases with further increasing the temperature up to 300 °C. The changes in the tensile properties of the alloy are associated with the post-annealing microstructure and modes of fracture.

  19. Effect of annealing ambient on the ferromagnetism of Mn-doped anatase TiO2 films

    NASA Astrophysics Data System (ADS)

    Xu, J. P.; Wang, J. F.; Lin, Y. B.; Liu, X. C.; Lu, Z. L.; Lu, Z. H.; Lv, L. Y.; Zhang, F. M.; Du, Y. W.

    2007-08-01

    The magnetic properties of anatase Ti1-xMnxO2 (0 < x < 0.06) films prepared by sol-gel spin coating annealed in air and vacuum have been investigated. Room temperature ferromagnetism was observed in all the films. Enhancement of ferromagnetism is revealed in the films annealed in vacuum. The magnetic moment of the films annealed in vacuum, at 300 K, is 0.285 ± 0.004 ?B/Mn for Ti0.9618Mn0.0382 O2 and 0.366 ± 0.005 ?B/Mn for Ti0.9409 Mn0.0591O2. It is believed that the enhanced ferromagnetism could be due to the formation of oxygen vacancies and/or defects.

  20. Transport phenomena in nanofluidics

    Microsoft Academic Search

    Reto B. Schoch; Jongyoon Han; Philippe Renaud

    2008-01-01

    The transport of fluid in and around nanometer-sized objects with at least one characteristic dimension below 100nm enables the occurrence of phenomena that are impossible at bigger length scales. This research field was only recently termed nanofluidics, but it has deep roots in science and technology. Nanofluidics has experienced considerable growth in recent years, as is confirmed by significant scientific

  1. Thin films of FeVO 4 obtained by annealing under room atmosphere of Fe and V layers sequentially deposited

    Microsoft Academic Search

    E. Baba Ali; J. C Bernède; A Barreau

    2000-01-01

    Metallic thin films Fe\\/V\\/Fe\\/V... \\/V sequentially deposited under vacuum have been annealed half an hour in room atmosphere. The samples have been characterised by X-rays diffraction (XRD), scanning electron microscopy (SEM), microprobe analysis (EDX), X-ray photoelectron spectroscopy (XPS) and optical absorption. The annealing temperature and the under layer material have been taken as parameters. The results have shown that triclinic

  2. Thermal and ion induced annealing of nanocrystalline ZnO thin film deposited by atom beam sputtering

    NASA Astrophysics Data System (ADS)

    Agarwal, D. C.; Singh, F.; Kabiraj, D.; Sen, S.; Kulariya, P. K.; Sulania, I.; Nozaki, S.; Chauhan, R. S.; Avasthi, D. K.

    2008-02-01

    ZnO thin films were deposited using atom beam sputtering and their modifications have been shown by two processes: (a) thermal annealing of ZnO thin films in oxygen and (b) athermal annealing by irradiation of these films by swift heavy ions (SHIs) in a high vacuum chamber. The as-deposited films showed the nanocrystalline nature with a preferred orientation along the c-axis of the hexagonal structure as revealed by x-ray diffraction (XRD) and Raman spectra. The influence of the thermal annealing and athermal annealing on the structural and surface modifications of these thin films were investigated. XRD and Raman spectroscopy confirmed the improvement in the crystallinity of ZnO thin film by both thermal annealing and SHI irradiation. The Zn-O bonding was confirmed by Fourier transform infrared spectroscopy and the interpretation of IR spectra corroborated the XRD and Raman results. Surface morphology was investigated by atomic force microscopy. The AFM study of the films implied no significant change in the roughness of the films in both types of annealing conditions. It was concluded that the modification of nanocrystalline ZnO thin film could be possible by both thermal and athermal annealing. Results indicate that transient annealing by SHI irradiation induces the highly textured c-axis oriented ZnO thin film for device applications, comparable to those of high temperature annealing.

  3. Influence of Annealing on the Optical Parameters of In2S3 Thin Films Produced by Thermal Evaporation

    NASA Astrophysics Data System (ADS)

    Izadneshan, H.; Gremenok, V. F.

    2014-05-01

    In2S3 thin fi lms are grown on glass substrates by vacuum thermal evaporation followed by annealing in vacuum between 330 and 400 °C for different time durations. We have investigated the infl uence of the annealing parameters on the characteristics of thin fi lms. It is shown that thermal treatment changed the crystal structure and optical energy band gap of In2S3 thin fi lms. Two energy band gaps were determined for all the fi lms, one indirect and the other direct.

  4. High power, high frequency, vacuum flange

    DOEpatents

    Felker, B.; McDaniel, M.R.

    1993-03-23

    An improved waveguide flange is disclosed for high power operation that helps prevent arcs from being initiated at the junctions between waveguide sections. The flanges at the end of the waveguide sections have counter bores surrounding the waveguide tubes. When the sections are bolted together the counter bores form a groove that holds a fully annealed copper gasket. Each counterbore has a beveled step that is specially configured to insure the gasket forms a metal-to-metal vacuum seal without gaps or sharp edges. The resultant inner surface of the waveguide is smooth across the junctions between waveguide sections, and arcing is prevented.

  5. Membrane Transport Phenomena (MTP)

    NASA Technical Reports Server (NTRS)

    Mason, Larry W.

    1997-01-01

    The third semi-annual period of the MTP project has been involved with performing experiments using the Membrane Transport Apparatus (MTA), development of analysis techniques for the experiment results, analytical modeling of the osmotic transport phenomena, and completion of a DC-9 microgravity flight to test candidate fluid cell geometries. Preparations were also made for the MTP Science Concept Review (SCR), held on 13 June 1997 at Lockheed Martin Astronautics in Denver. These activities are detailed in the report.

  6. Educational Vacuum Trainers

    NSDL National Science Digital Library

    Hansen, Steve

    Have you inherited a bell jar vacuum system and are scratching your head over how to set it up or are unsure of its operations or capabilities? Or do you want to do more with your bell jar vacuum? The forum on Bell Jar Vacuums - with the topic Vacuum Trainers can help you. The intent of this forum is for this to be a place where technical issues, classroom exercises, activities, etc. can be discussed. There's no endorsement by manufacturers and commercial issues are off limits. Steve Hansen (bell jar expert) gives some brief descriptions of the vacuum trainers that are or have been available over the past decade or so - Varian, MKS, Science Source, American Vacuum Society. Links are provided to various data sheets, articles and online exercises. Steve, the forum moderator has experience in all of these.Keywords: vacuum, "vacuum trainer","bell jar" and/or belljar, MKSVarian, VPAL, VTS, sputtering, plasma

  7. Radiation hard vacuum switch

    DOEpatents

    Boettcher, Gordon E. (Albuquerque, NM)

    1990-01-01

    A vacuum switch with an isolated trigger probe which is not directly connected to the switching electrodes. The vacuum switch within the plasmatron is triggered by plasma expansion initiated by the trigger probe which travels through an opening to reach the vacuum switch elements. The plasma arc created is directed by the opening to the space between the anode and cathode of the vacuum switch to cause conduction.

  8. Multidimensional Scaling by Deterministic Annealing

    Microsoft Academic Search

    Hansjörg Klock; Joachim M. Buhmann

    1997-01-01

    . Multidimensional scaling addresses the problem how proximitydata can be faithfully visualized as points in a low-dimensionalEuclidian space. The quality of a data embedding is measured by a costfunction called stress which compares proximity values with Euclidiandistances of the respective points. We present a novel deterministic annealing algorithm to efficiently determine embedding coordinates for thiscontinuous optimization problem. Experimental results demonstrate

  9. Simulated annealing with extended neighbourhood

    Microsoft Academic Search

    Xin Yao

    1991-01-01

    Simulated Annealing (SA) is a powerful stochastic search method applicable to a wide range of problems for which little prior knowledge is available. It can produce very high quality solutions for hard combinatorial optimization problems. However, the computation time required by SA is very large. Various methods have been proposed to reduce the computation time, but they mainly deal with

  10. An Introduction to Simulated Annealing

    ERIC Educational Resources Information Center

    Albright, Brian

    2007-01-01

    An attempt to model the physical process of annealing lead to the development of a type of combinatorial optimization algorithm that takes on the problem of getting trapped in a local minimum. The author presents a Microsoft Excel spreadsheet that illustrates how this works.

  11. Convergence of an annealing algorithm

    Microsoft Academic Search

    M. Lundy; A. Mees

    1986-01-01

    The annealing algorithm is a stochastic optimization method which has attracted attention because of its success with certain difficult problems, including NP-hard combinatorial problems such as the travelling salesman, Steiner trees and others. There is an appealing physical analogy for its operation, but a more formal model seems desirable. In this paper we present such a model and prove that

  12. Anode-Spot Formation and Motion of Vacuum Arcs

    Microsoft Academic Search

    A. Kaltenecker; M. Schussek

    1985-01-01

    This paper reports about experimental investigations on high-current vacuum-arc phenomena, especially anode-spot formation, arc states, and motion. The presented work was stimulated by lack of information about the transition process from the diffuse low-current mode to the high-current mode characterized by anode spot(s). Optoelectronic measurements, streak photographs, high-speed movies, and correlated arc voltage\\/current records yielded remarkable results on power-frequency vacuum

  13. Effect of Annealing Ambient on the Electrical and Optical Properties of Aluminum-Doped ZnO Films Produced via a Sol-Gel Process

    NASA Astrophysics Data System (ADS)

    Ho, Yung-Shou; Chen, Yi-Siou; Wu, Cheng-Heng

    2014-07-01

    In this study, aluminum-doped ZnO (AZO) thin films were prepared by a sol-gel with spin coating process. The AZO films were annealed by a two-step process. The films were first annealed in air or nitrogen at 500°C for 3 h, followed by annealing in three types of ambient, i.e., vacuum (10-3 Torr or 10-6 Torr) or forming gas (10% H2/90% N2), at 500°C for 4 h. The effect of the annealing ambient on the microstructure, electrical and optical properties of the AZO films was explored by x-ray diffraction, field-emission scanning electron microscopy, four-point probe sheet resistivity measurements, Hall voltage measurements, and ultraviolet-visible spectroscopy. The results showed that the size of AZO particulates in the films was determined mainly by the first annealing step. The films annealed in air in the first step were composed of larger AZO particulates than those annealed in nitrogen. The conductivities of the AZO films were significantly increased by the second annealing step. Second annealing in a high-vacuum system (10-6 Torr) led to the highest AZO film conductivity among the three ambients. Regardless of the various annealing processes, the films remained transparent under visible light and exhibited a sharp absorption edge in the ultraviolet region. The highest conductivity, i.e., 168 S cm-1, was obtained from films annealed first in air and then in vacuum of 10-6 Torr.

  14. In situ laser annealing system for real-time surface kinetic analysis

    NASA Astrophysics Data System (ADS)

    Wang, Q.; Sun, Y.-M.; Zhao, W.; Campagna, J.; White, J. M.

    2002-11-01

    For real-time analysis during thermal annealing, a continuous wave CO2 infrared laser was coupled to a surface analysis system equipped for x-ray photoelectron spectroscopy (XPS) and ion scattering spectroscopy (ISS). The laser beam was directed into the vacuum chamber through a ZnSe window to the back side of the sample. With 10 W laser output, the sample temperature reached 563 K. The chamber remained below 10-8 Torr during annealing and allowed XPS and ISS data to be gathered as a function of time at selected temperatures. As a test example, real time Cu2O reduction at 563 K was investigated.

  15. Quantum Annealing for Variational Bayes Inference

    E-print Network

    Issei Sato; Kenichi Kurihara; Shu Tanaka; Hiroshi Nakagawa; Seiji Miyashita

    2009-05-28

    This paper presents studies on a deterministic annealing algorithm based on quantum annealing for variational Bayes (QAVB) inference, which can be seen as an extension of the simulated annealing for variational Bayes (SAVB) inference. QAVB is as easy as SAVB to implement. Experiments revealed QAVB finds a better local optimum than SAVB in terms of the variational free energy in latent Dirichlet allocation (LDA).

  16. ANNEALED THEORIES OF LEARNING H. S. Seung

    E-print Network

    Seung, Sebastian

    ANNEALED THEORIES OF LEARNING H. S. Seung AT&T Bell Laboratories Murray Hill, NJ 07974 E-mail: seung@physics.att.com ABSTRACT We study annealed theories of learning boolean functions using a concept class of nite cardinality. The naive annealed theory can be used to derive a univer- sal learning curve

  17. Critical Acceleration and Quantum Vacuum

    E-print Network

    Johann Rafelski; Lance Labun

    2012-04-22

    Little is known about the physics frontier of strong acceleration; both classical and quantum physics need further development in order to be able to address this newly accessible area of physics. In this lecture we discuss what strong acceleration means and possible experiments using electron-laser collisions and, data available from ultra-relativistic heavy ion collisions. We review the foundations of the current understanding of charged particle dynamics in presence of critical forces and discuss the radiation reaction inconsistency in electromagnetic theory and the apparent relation with quantum physics and strong field particle production phenomena. The role of the quantum vacuum as an inertial reference frame is emphasized, as well as the absence of such a `Machian' reference frame in the conventional classical limit of quantum field theory.

  18. Breakdown phenomena in high power klystrons

    SciTech Connect

    Vlieks, A.E.; Allen, M.A.; Callin, R.S.; Fowkes, W.R.; Hoyt, E.W.; Lebacqz, J.V.; Lee, T.G.

    1988-03-01

    In the course of developing new high peak power klystrons at SLAC, high electric fields in several regions of these devices have become an important source of vacuum breakdown phenomena. In addition, a renewed interest in breakdown phenomena for nanosecond pulse, multi-megavolt per centimeter fields has been sparked by recent R and D work in the area of gigawatt RF sources. The most important regions of electrical breakdown are in the output cavity gap area, the RF ceramic windows, and the gun ceramic insulator. The details of the observed breakdown in these regions, experiments performed to understand the phenomena and solutions found to alleviate the problems will be discussed. Recently experiments have been performed on a new prototype R and D klystron. Peak electric fields across the output cavity gaps of this klystron exceed 2 MV/cm. The effect of peak field duration (i.e. pulse width) on the onset of breakdown have been measured. The pulse widths varied from tens of nanoseconds to microseconds. Results from these experiments will be presented. The failure of ceramic RF windows due to multipactor and puncturing was an important problem to overcome in order that our high power klystrons would have a useful life expectancy. Consequently many studies and tests were made to understand and alleviate window breakdown phenomena. Some of the results in this area, especially the effects of surface coatings, window materials and processing techniques and their effects on breakdown will be discussed. Another important source of klystron failure in the recent past at SLAC has been the puncturing of the high voltage ceramic insulator in the gun region. A way of alleviating this problem has been found although the actual cause of the puncturing is not yet clear. The ''practical'' solution to this breakdown process will be described and a possible mechanism for the puncturing will be presented. 9 refs., 5 figs., 3 tabs.

  19. MULTISCALE PHENOMENA IN MATERIALS

    SciTech Connect

    A. BISHOP

    2000-09-01

    This project developed and supported a technology base in nonequilibrium phenomena underpinning fundamental issues in condensed matter and materials science, and applied this technology to selected problems. In this way the increasingly sophisticated synthesis and characterization available for classes of complex electronic and structural materials provided a testbed for nonlinear science, while nonlinear and nonequilibrium techniques helped advance our understanding of the scientific principles underlying the control of material microstructure, their evolution, fundamental to macroscopic functionalities. The project focused on overlapping areas of emerging thrusts and programs in the Los Alamos materials community for which nonlinear and nonequilibrium approaches will have decisive roles and where productive teamwork among elements of modeling, simulations, synthesis, characterization and applications could be anticipated--particularly multiscale and nonequilibrium phenomena, and complex matter in and between fields of soft, hard and biomimetic materials. Principal topics were: (i) Complex organic and inorganic electronic materials, including hard, soft and biomimetic materials, self-assembly processes and photophysics; (ii) Microstructure and evolution in multiscale and hierarchical materials, including dynamic fracture and friction, dislocation and large-scale deformation, metastability, and inhomogeneity; and (iii) Equilibrium and nonequilibrium phases and phase transformations, emphasizing competing interactions, frustration, landscapes, glassy and stochastic dynamics, and energy focusing.

  20. S (LLV, 150 eV) and C (KLL, 265 eV) Auger peaks scale with varied TTPO coverage C peak loses significance in prolonged study as it is present following thermal annealing beyond TTPO

    E-print Network

    New Hampshire, University of

    -high vacuum chamber (~10-10 mbar) Deposition and AES analysis performed in situ TTPO deposited by physical significance in prolonged study as it is present following thermal annealing beyond TTPO decomposition of indicator peaks following thermal anneal, 250º C

  1. Crystallization phenomena in slags

    NASA Astrophysics Data System (ADS)

    Orrling, Carl Folke

    2000-09-01

    The crystallization of the mold slag affects both the heat transfer and the lubrication between the mold and the strand in continuous casting of steel. In order for mold slag design to become an engineering science rather than an empirical exercise, a fundamental understanding of the melting and solidification behavior of a slag must be developed. Thus it is necessary to be able to quantify the phenomena that occur under the thermal conditions that are found in the mold of a continuous caster. The double hot thermocouple technique (DHTT) and the Confocal Laser Scanning Microscope used in this study are two novel techniques for investigating melting and solidification phenomena of transparent slags. Results from these techniques are useful in defining the phenomena that occur when the slag film infiltrates between the mold and the shell of the casting. TTT diagrams were obtained for various slags and indicated that the onset of crystallization is a function of cooling rate and slag chemistry. Crystal morphology was found to be dependent upon the experimental temperature and four different morphologies were classified based upon the degree of melt undercooling. Continuous cooling experiments were carried out to develop CCT diagrams and it was found that the amount and appearance of the crystalline fraction greatly depends on the cooling conditions. The DHTT can also be used to mimic the cooling profile encountered by the slag in the mold of a continuous caster. In this differential cooling mode (DCT), it was found that the details of the cooling rate determine the actual response of the slag to a thermal gradient and small changes can lead to significantly different results. Crystal growth rates were measured and found to be in the range between 0.11 mum/s to 11.73 mum/s depending on temperature and slag chemistry. Alumina particles were found to be effective innoculants in oxide melts reducing the incubation time for the onset of crystallization and also extending the temperature range of observed crystallization. The effect of changing the gas atmosphere surrounding the sample has been studied. The presence of water vapor increased the nucleation rate and crystal growth rate significantly when compared to experiments carried out in a dry atmosphere. With an atmosphere of Argon and Argon-3% Hydrogen mixture, the incubation time for crystallization was increased with several minutes. The crystal growth rate in these atmospheres was also drastically reduced compared to an atmosphere of normal air. Significant numbers of bubbles were formed during the initial melting of mold slag samples and the melting rate of the slag was found to be related to the rate of bubble generation and to the rate of heat transport.

  2. Attoheat transport phenomena

    E-print Network

    J. Marciak-Kozlowska; M. Pelc; M. A. Kozlowski

    2009-06-09

    Fascinating developments in optical pulse engineering over the last 20 years lead to the generation of laser pulses as short as few femtosecond, providing a unique tool for high resolution time domain spectroscopy. However, a number of the processes in nature evolve with characteristic times of the order of 1 fs or even shorter. Time domain studies of such processes require at first place sub-fs resolution, offered by pulse depicting attosecond localization. The generation, characterization and proof of principle applications of such pulses is the target of the attoscience. In the paper the thermal processes on the attosecond scale are described. The Klein-Gordon and Proca equations are developed. The relativistic effects in the heat transport on nanoscale are discussed. It is shown that the standard Fourier equation can not be valid for the transport phenomena induced by attosecond laser pulses. The heat transport in nanoparticles and nanotubules is investigated.

  3. Weld pool phenomena

    SciTech Connect

    David, S.A.; Vitek, J.M.; Zacharia, T. [Oak Ridge National Lab., TN (United States); DebRoy, T. [Pennsylvania State Univ., University Park, PA (United States)

    1994-09-01

    During welding, the composition, structure and properties of the welded structure are affected by the interaction of the heat source with the metal. The interaction affects the fluid flow, heat transfer and mass transfer in the weld pool, and the solidification behavior of the weld metal. In recent years, there has been a growing recognition of the importance of the weld pool transport processes and the solid state transformation reactions in determining the composition, structure and properties of the welded structure. The relation between the weld pool transport processes and the composition and structure is reviewed. Recent applications of various solidification theories to welding are examined to understand the special problems of weld metal solidification. The discussion is focussed on the important problems and issues related to weld pool transport phenomena and solidification. Resolution of these problems would be an important step towards a science based control of composition, structure and properties of the weld metal.

  4. In situ monitoring of ion sputtering and thermal annealing of crystalline surfaces using an oblique-incidence optical

    E-print Network

    Zhu, Xiangdong

    in an ultrahigh vacuum chamber. The base pressure during experiment is around 2 10 10 Torr. The surfaceIn situ monitoring of ion sputtering and thermal annealing of crystalline surfaces using an oblique 1998 We demonstrate that the morphology of crystalline surfaces during ion sputtering and thermal

  5. Recursive Branching Simulated Annealing Algorithm

    NASA Technical Reports Server (NTRS)

    Bolcar, Matthew; Smith, J. Scott; Aronstein, David

    2012-01-01

    This innovation is a variation of a simulated-annealing optimization algorithm that uses a recursive-branching structure to parallelize the search of a parameter space for the globally optimal solution to an objective. The algorithm has been demonstrated to be more effective at searching a parameter space than traditional simulated-annealing methods for a particular problem of interest, and it can readily be applied to a wide variety of optimization problems, including those with a parameter space having both discrete-value parameters (combinatorial) and continuous-variable parameters. It can take the place of a conventional simulated- annealing, Monte-Carlo, or random- walk algorithm. In a conventional simulated-annealing (SA) algorithm, a starting configuration is randomly selected within the parameter space. The algorithm randomly selects another configuration from the parameter space and evaluates the objective function for that configuration. If the objective function value is better than the previous value, the new configuration is adopted as the new point of interest in the parameter space. If the objective function value is worse than the previous value, the new configuration may be adopted, with a probability determined by a temperature parameter, used in analogy to annealing in metals. As the optimization continues, the region of the parameter space from which new configurations can be selected shrinks, and in conjunction with lowering the annealing temperature (and thus lowering the probability for adopting configurations in parameter space with worse objective functions), the algorithm can converge on the globally optimal configuration. The Recursive Branching Simulated Annealing (RBSA) algorithm shares some features with the SA algorithm, notably including the basic principles that a starting configuration is randomly selected from within the parameter space, the algorithm tests other configurations with the goal of finding the globally optimal solution, and the region from which new configurations can be selected shrinks as the search continues. The key difference between these algorithms is that in the SA algorithm, a single path, or trajectory, is taken in parameter space, from the starting point to the globally optimal solution, while in the RBSA algorithm, many trajectories are taken; by exploring multiple regions of the parameter space simultaneously, the algorithm has been shown to converge on the globally optimal solution about an order of magnitude faster than when using conventional algorithms. Novel features of the RBSA algorithm include: 1. More efficient searching of the parameter space due to the branching structure, in which multiple random configurations are generated and multiple promising regions of the parameter space are explored; 2. The implementation of a trust region for each parameter in the parameter space, which provides a natural way of enforcing upper- and lower-bound constraints on the parameters; and 3. The optional use of a constrained gradient- search optimization, performed on the continuous variables around each branch s configuration in parameter space to improve search efficiency by allowing for fast fine-tuning of the continuous variables within the trust region at that configuration point.

  6. Formation of Nanocomposites by Oxidizing Annealing of SiO x and SiO x Films: Ellipsometry and FTIR Analysis.

    PubMed

    Sopinskyy, Mykola V; Vlasenko, Natalya A; Lisovskyy, Igor P; Zlobin, Sergii O; Tsybrii, Zinoviia F; Veligura, Lyudmyla I

    2015-01-01

    The structural-phase transformations induced by air annealing of SiO x and SiO x ??films were studied by the combined use of infrared spectroscopy and ellipsometry. The films were prepared using vacuum evaporation of SiO powder and co-evaporation of SiO and ErF3 powders. The annealing took place at moderate temperatures (750 and 1000 °C). It was found that the micro- and macrostructure of the annealed films is similar to the structure of the Si-SiO x nanocomposites obtained by annealing SiO x in vacuum or inert atmosphere and subjected to post-annealing in oxidizing atmosphere. This proves that the phase separation in the non-stoichiometric SiO x films proceeds much faster than their oxidation. The results of the work point at a possibility to simplify the annealing technology by replacing the two-step annealing with one-step in the oxygen-containing environment while maintaining the positive effects. The differences in the structure of the nanocomposites obtained by annealing the SiO x and SiO x ??films are explained by the action of Er centers as the promoters for SiO x disproportionation, as well as the enhanced action of F on the processes of disorder-to-order transition and crystallization in amorphous silicon. PMID:26034423

  7. Vacuum probe surface sampler

    NASA Technical Reports Server (NTRS)

    Zahlava, B. A. (inventor)

    1973-01-01

    A vacuum probe surface sampler is described for rapidly sampling relatively large surface areas which possess relatively light loading densities of micro-organism, drug particles or the like. A vacuum head with a hollow handle connected to a suitable vacuum source is frictionally attached to a cone assembly terminating in a flared tip adapted to be passed over the surface to be sampled. A fine mesh screen carried by the vacuum head provides support for a membrane filter which collects the microorganisms or other particles. The head assembly is easily removed from the cone assembly without contacting the cone assembly with human hands.

  8. Exoelectron emission from a clean, annealed magnesium single crystal during oxygen adsorption

    NASA Technical Reports Server (NTRS)

    Ferrante, J.

    1976-01-01

    Exoelectron emission has been observed from a clean, annealed Mg (0001) surface during oxygen and chlorine adsorption at pressures of 0.000065 N/sq m and lower. The studies were performed in an ultrahigh vacuum system. The crystals were cleaned by argon-ion bombardment and annealed at 300 C. Auger electron spectroscopy was used to verify surface cleanliness, and low-energy electron diffraction was used to verify that the surface was annealed. The emission was found to be dependent on oxygen arrival rate. Two peaks were observed in the electron emission with exposure. Evidence is presented that the formation of the second peak corresponds to oxidation of the Mg surface. The results verify that electron emission occurs from a strain-free surface simply upon adsorption of oxygen. A qualitative explanation for the mechanisms of emission in terms of chemical effects is presented.

  9. Exoelectron emission from a clean, annealed magnesium single crystal during oxygen adsorption

    NASA Technical Reports Server (NTRS)

    Ferrante, J.

    1976-01-01

    Exoelectron emission was observed from a clean, annealed Mg (0001) surface during oxygen and chlorine adsorption at pressures of 6.5x10 0.00001- N/sq m and lower. the studies were performed in an ultrahigh vacuum system. The crystals were cleaned by argon ion bombardment and annealed at 300 C. Auger electron spectroscopy was used to verify surface cleanliness, and low energy electron diffraction was used to verify that the surface was annealed. The emission was found to be oxygen arrival rate dependent. Two peaks were observed in the electron emission with exposure. Evidence is presented that the formation of the second peak corresponds to oxidation of the Mg surface. No emission was observed from clean aluminum during adsorption. Results verify that electron emission occurs from a strain free surface simply upon adsorption of oxygen. A qualitative explanation for the mechanisms of emission in terms of chemical effects is presented.

  10. Current transport analysis of ZrO2 thin films: Effects of post-deposition annealing

    NASA Astrophysics Data System (ADS)

    Jeong, Heejun

    2014-12-01

    We report on the effects of post-deposition annealing on the electrical properties and the dielectric performance of atomic layer-deposited ZrO2 thin films investigated by using capacitance-voltage and current-voltage measurements. ZrO2 films crystallized by post-deposition annealing in vacuum showed an enhanced dielectric constant and energy band gap, but the leakage current was increased. The Poole-Frankel and the trap assisted tunneling mechanisms were considered to be the major leakage current conduction processes and the charge trap energy level was reduced from 1.09-1.13 eV to 0.81-0.84 eV by post-deposition annealing. The increase in the leakage current in the crystallized films can be explained by considering structural defect relaxation or grain boundary formation.

  11. Effect of annealing on properties of CuInS2 thin films

    Microsoft Academic Search

    R. Brini; M. Kanzari; B. Rezig; J. Werckmann

    2005-01-01

    Surface morphology, structural and optical properties of CuInS{2} thin films grown by the single source thermal evaporation in vacuum have been studied. The films were annealed from 250 to 550 ° C in argon atmosphere with low oxygen concentration (O{2}<2 ppm). CuInS{2} films are characterized by scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), X-ray diffraction (XRD) and optical

  12. Effect of parallel circuit parameters on the instability of a low-current vacuum arc

    Microsoft Academic Search

    Cuie Ding; Satoru Yanabu

    2003-01-01

    To clarify the instability phenomena of a low-current vacuum arc, we observe the phenomena by changing the parallel circuit parameters. We measure instability-initiation current, chopping current, arc voltage, reignition voltage peak, and the transient recovery voltage by using copper, copper chromium, copper tungsten, and silver tungsten carbide electrodes. We find that the chopping current, reignition voltage peak, and transient recovery

  13. About the connection between vacuum birefringence and the light-light scattering amplitude

    E-print Network

    J. Haissinski; S. Dagoret; M. Urban; F. Zomer

    2006-11-10

    Birefringence phenomena stemming from vacuum polarization are revisited in the framework of coherent scattering. Based on photon-photon scattering, our analysis brings out the direct connection between this process and vacuum birefringence. We show how this procedure can be extended to the Kerr and the Cotton-Mouton birefringences in vacuum, thus providing a unified treatment of various polarization schemes, including those involving static fields.

  14. Conductive layers in diamond formed by hydrogen ion implantation and annealing

    NASA Astrophysics Data System (ADS)

    Popov, V. P.; Safronov, L. N.; Naumova, O. V.; Nikolaev, D. V.; Kupriyanov, I. N.; Palyanov, Yu. N.

    2012-07-01

    High conductivity is extremely difficult to obtain in diamond due to its wide band gap and low solubility of dopands. The goal of the investigation was to form a conductor inside HPHT synthetic diamond plates with initial high sheet resistivity ?s (˜1012 ?/sq) for 400 ?m thickness. We used metastable character of diamond structures relative to the graphitization of defective layers formed by 50 keV hydrogen molecular ions at high fluence ? = (1-13) × 1016 cm-2 ion implantation. High temperature (HT) (500-1600 °C) and vacuum or high pressure (VP/HP) (3 × 10-3/4 × 109 Pa) thermal annealing were chosen to provide the annealing regimes where the graphitic carbon is the most stable phase. Sheet resistance, dropped down up to nine orders of magnitude (?s ˜ 103 ?/sq), as well as Raman spectroscopy, and AFM measurements were used to determine electrical, optical and geometrical properties of multilayered heterostructures formed in the set of experiments. Temperature dependences of the conductivity show, that after highest fluencies and annealing temperatures the conductivity is quasimetallic and electronic system is above metal-insulator transition (MIT). At lower fluences and/or annealing temperatures the system is under MIT with the transport of charge carriers being well described by variable range hopping (VRH) mechanism with variable decay length of wave function for localized states. Two or three order of magnitude differences in the conductivity in VP and HP annealed samples are attributed with the higher dimensions of graphite nanocrystals in the case of vacuum annealing. This suggestion coincides with Raman spectra and optimum hopping length for carrier jumps in VRH model for conductivity in the buried layers.

  15. Elevated temperature annealing of the neutron induced reverse current and corresponding defect levels in low and high resistivity silicon detectors

    Microsoft Academic Search

    V. Eremin; A. Ivanov; E. Verbitskaya; Z. Li; H. W. Kraner

    1995-01-01

    A new aspect of degradation phenomena of neutron irradiated silicon detectors has been revealed which consists in the significant influence of carbon related defect transformation on the detector reverse current (Irev). The annealing of the reverse current at elevated temperatures and the corresponding changes of the deep level transient spectroscopy (DLTS) spectra of defects for fast neutron irradiated silicon detectors,

  16. Highest transmittance and high-mobility amorphous indium gallium zinc oxide films on flexible substrate by room-temperature deposition and post-deposition anneals

    SciTech Connect

    Gadre, Mandar J. [School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, Arizona 85287 (United States); Alford, T. L. [School for Engineering of Matter, Transport and Energy, Arizona State University, Tempe, Arizona 85287 (United States); Flexible Display Center at Arizona State University, Tempe, Arizona 85284 (United States)

    2011-08-01

    Amorphous indium gallium zinc oxide (a-IGZO) thin films of the highest transmittance reported in literature were initially deposited onto flexible polymer substrates at room temperature. The films were annealed in vacuum, air, and oxygen to enhance their electrical and optical performances. Electrical and optical characterizations were done before and after anneals. A partial reversal of the degradation in electrical properties upon annealing in oxygen was achieved by subjecting the films to subsequent vacuum anneals. A model was developed based on film texture and structural defects which showed close agreement between the measured and calculated carrier mobility values at low carrier concentrations (2-6 x 10{sup 19} cm{sup -3}).

  17. Chapter 13. The Vacuum System

    E-print Network

    Brookhaven National Laboratory - Experiment 821

    to the exact radius for a 28 degree arc. A short aluminum bellows adapter is placed between each vacuum chamberChapter 13. The Vacuum System Revised February 1994 13.1. The Vacuum Chambers A plan view of the assembled vacuum chamber ring is shown in Fig. 13.1.1. The vacuum chamber ring includes twelve 28 degree

  18. Superlattice Phenomena in Nanohelices

    NASA Astrophysics Data System (ADS)

    Downing, Charles; Robinson, Matthew; Portnoi, Mikhail; University of Exeter Team

    2015-03-01

    Recently artificially-created nanohelices have been demonstrated in various semiconductor systems. We argue that subjecting a nanohelix to an electric field normal to its axis turns it into a superlattice with easily-tunable electronic properties. We investigate such a system, also subjected to a longitudinal electric field along the nanotube axis, and find Bloch oscillations and negative differential conductivity. Taking into account Zener tunneling across the band gap, we find the characteristic N-type dependence of electron drift velocity on the longitudinal field which is commonly used in high-frequency electronics. The merits of using a nanohelix for novel tunable device applications are assessed. We also study dipole transitions across the energy gap, which can be tuned to the THz range by experimentally attainable external fields. There is a drastic change in selection rules for a helix in a transverse field compared to the case of purely chiral structures. For the excitation propagating along the nanohelix axis our results are somewhat similar to those found for a quantum ring pierced by a magnetic flux, with the momentum of a quasiparticle in a helix playing the same role as a flux through a ring. We also discuss possible devices which could utilize these phenomena.

  19. ON DETECTING TRANSIENT PHENOMENA

    SciTech Connect

    Belanger, G., E-mail: gbelanger@sciops.esa.int [European Space Astronomy Centre (ESA/ESAC), Science Operations Department, Villanueva de la Canada (Madrid) (Spain)

    2013-08-10

    Transient phenomena are interesting and potentially highly revealing of details about the processes under observation and study that could otherwise go unnoticed. It is therefore important to maximize the sensitivity of the method used to identify such events. In this article, we present a general procedure based on the use of the likelihood function for identifying transients which is particularly suited for real-time applications because it requires no grouping or pre-processing of the data. The method makes use of all the information that is available in the data throughout the statistical decision-making process, and is suitable for a wide range of applications. Here we consider those most common in astrophysics, which involve searching for transient sources, events or features in images, time series, energy spectra, and power spectra, and demonstrate the use of the method in the case of a weak X-ray flare in a time series and a short-lived quasi-periodic oscillation in a power spectrum. We derive a fit statistic that is ideal for fitting arbitrarily shaped models to a power density distribution, which is of general interest in all applications involving periodogram analysis.

  20. Arcjet cathode phenomena

    NASA Technical Reports Server (NTRS)

    Curran, Francis M.; Haag, Thomas W.; Raquet, John F.

    1989-01-01

    Cathode tips made from a number of different materials were tested in a modular arcjet thruster in order to examine cathode phenomena. Periodic disassembly and examination, along with the data collected during testing, indicated that all of the tungsten-based materials behaved similarly despite the fact that in one of these samples the percentage of thorium oxide was doubled and another was 25 percent rhenium. The mass loss rate from a 2 percent thoriated rhenium cathode was found to be an order of magnitude greater than that observed using 2 percent thoriated tungsten. Detailed analysis of one of these cathode tips showed that the molten crater contained pure tungsten to a depth of about 150 microns. Problems with thermal stress cracking were encountered in the testing of a hafnium carbide tip. Post test analysis showed that the active area of the tip had chemically reacted with the propellant. A 100 hour continuous test was run at about 1 kW. Post test analysis revealed no dendrite formation, such as observed in a 30 kW arcjet lifetest, near the cathode crater. The cathodes from both this test and a previously run 1000 hour cycled test displayed nearly identical arc craters. Data and calculations indicate that the mass losses observed in testing can be explained by evaporation.

  1. Arcjet Cathode Phenomena

    NASA Technical Reports Server (NTRS)

    Curran, Francis M.; Haag, Thomas W.; Raquet, John F.

    1989-01-01

    Cathode tips made from a number of different materials were tested in a modular arcjet thruster in order to examine cathode phenomena. Periodic disassembly and examination, along with the data collected during testing, indicated that all of the tungsten-based materials behaved similarly despite the fact that in one of these samples the percentage of thorium oxide was doubled and another was 25 percent rhenium. The mass loss rate from a 2 percent thoriated rhenium cathode was found to be an order of magnitude greater than that observed using 2 percent thoriated tungsten. Detailed analysis of one of these cathode tips showed that the molten crater contained pure tungsten to a depth of about 150 microns. Problems with thermal stress cracking were encountered in the testing of a hafnium carbide tip. Post test analysis showed that the active area of the tip had chemically reacted with the propellant. A 100 hour continuous test was run at about 1 kW. Post test analysis revealed no dendrite formation, such as observed in a 30 kW arcjet lifetest, near the cathode crater. The cathodes from both this test and a previously run 1000 hour cycled test displayed nearly identical arc craters. Data and calculations indicate that the mass losses observed in testing can be explained by evaporation.

  2. Photon acceleration in vacuum

    E-print Network

    J. T. Mendonca; M. Marklund; P. K. Shukla; G. Brodin

    2006-08-16

    A new process associated with the nonlinear optical properties of the electromagnetic vacuum, as predicted by quantum electrodynamics, is described. This can be called photon acceleration in vacuum, and corresponds to the frequency shift that takes place when a given test photon interacts with an intense beam of background radiation.

  3. Deterministic and Stochastic Quantum Annealing Approaches

    Microsoft Academic Search

    Demian Battaglia; Lorenzo Stella; Osvaldo Zagordi; Giuseppe E. Santoro; Erio Tosatti

    2005-01-01

    The idea of quantum annealing (QA) is a late offspring of the celebrated simulated thermal annealing by Kirkpatrick et al. [1]. In simulated annealing, the problem of minimizing a certain cost (or energy) function in a large\\u000a configuration space is tackled by the introduction of a fictitious temperature, which is slowly lowered in the course of a\\u000a Monte Carlo or

  4. Dual beam laser spike annealing technology

    Microsoft Academic Search

    Yun Wang; Shaoyin Chen; Michael Shen; Xiaoru Wang; Senquan Zhou; Jeff Hebb; David Owen

    2010-01-01

    A new dual-beam laser spike annealing (DB-LSA) technology is developed to expand the application space of non-melt laser annealing. In the standard LSA configuration, a single narrow laser beam is used to heat the wafer surface from substrate temperature to the peak annealing temperature close to silicon melt. In DB-LSA, a second wide laser beam is incorporated to preheat the

  5. Neutronic optimization in high conversion Th-{sup 233}U fuel assembly with simulated annealing

    SciTech Connect

    Kotlyar, D.; Shwageraus, E. [Dept. of Nuclear Engineering, Ben-Gurion Univ., POB 653, Beer Sheva 84105 (Israel)

    2012-07-01

    This paper reports on fuel design optimization of a PWR operating in a self sustainable Th-{sup 233}U fuel cycle. Monte Carlo simulated annealing method was used in order to identify the fuel assembly configuration with the most attractive breeding performance. In previous studies, it was shown that breeding may be achieved by employing heterogeneous Seed-Blanket fuel geometry. The arrangement of seed and blanket pins within the assemblies may be determined by varying the designed parameters based on basic reactor physics phenomena which affect breeding. However, the amount of free parameters may still prove to be prohibitively large in order to systematically explore the design space for optimal solution. Therefore, the Monte Carlo annealing algorithm for neutronic optimization is applied in order to identify the most favorable design. The objective of simulated annealing optimization is to find a set of design parameters, which maximizes some given performance function (such as relative period of net breeding) under specified constraints (such as fuel cycle length). The first objective of the study was to demonstrate that the simulated annealing optimization algorithm will lead to the same fuel pins arrangement as was obtained in the previous studies which used only basic physics phenomena as guidance for optimization. In the second part of this work, the simulated annealing method was used to optimize fuel pins arrangement in much larger fuel assembly, where the basic physics intuition does not yield clearly optimal configuration. The simulated annealing method was found to be very efficient in selecting the optimal design in both cases. In the future, this method will be used for optimization of fuel assembly design with larger number of free parameters in order to determine the most favorable trade-off between the breeding performance and core average power density. (authors)

  6. Indium-free, acid-resistant anatase Nb-doped TiO 2 electrodes activated by rapid-thermal annealing for cost-effective organic photovoltaics

    Microsoft Academic Search

    Jun-Hyuk Park; Seong Jun Kang; Seok-In Na; Hyun Hwi Lee; Sung-Wng Kim; H. Hosono; Han-Ki Kim

    2011-01-01

    Indium-free and acid-resistant anatase Nb-doped TiO2 (NTO) electrodes are promising as economical substitutes for high-cost Sn-doped In2O3 (ITO) films used in organic photovoltaics. By rapid-thermal annealing under an ambient vacuum, an insulating amorphous NTO film of low transparency was changed dramatically into a transparent and conductive anatase NTO electrode. Metallic conductivity of the annealed NTO electrode could be attributed to

  7. Enhanced magneto-optical effect due to interface alloy formation in CoPt (1 1 1) ultrathin lms upon thermal annealing

    E-print Network

    Lin, Minn-Tsong

    in an ultrahigh vacuum (UHV) chamber with base pressure in the range 5 Â 10À10 mbar. The UHV chamber was Applied upon thermal annealing M.-T. Lina,* , C.C. Kuoa , J.W. Hoa , Y.E. Wub , H.Y. Herb , C.S. Shernb , H; Perpendicular magnetic anisotropy; Ultrathin ®lm; Thermal annealing 1. Introduction Co±Pt based systems

  8. Increasing the strength of nanocrystalline steels by annealing: Is segregation necessary?

    PubMed Central

    Renk, O.; Hohenwarter, A.; Eder, K.; Kormout, K.S.; Cairney, J.M.; Pippan, R.

    2015-01-01

    Hardening phenomena in nanocrystalline metals after annealing have been widely reported, and the subject of much recent debate. Solute segregation to grain boundaries and dislocation source hardening have been proposed to cause the strengthening. To shed light on the dominant mechanisms, we present results from mechanical experiments and atom probe tomography on samples with similar grain size but different amounts of solute segregation and different boundary chemistries. PMID:25598694

  9. Initial stages of oxidation on single crystals of lithium hydride-interaction between single crystal lithium hydride and a stainless steel, high vacuum container

    SciTech Connect

    Simandl, R.F.; McLaughlin, J.F.

    1981-11-30

    Interaction between single crystals of lithium hydride (LiH) and surface contaminants found on clean stainless steel and gold-plated stainless steel containers during a high vacuum, 350/sup 0/C anneal contributed significantly to the oxidation of the single crystal surfaces. Annealing the samples in the presence of a clean, polycrystalline LiH getter in a hydrogen-reduced container significantly reduced surface oxidation. Thermal etching during the 350/sup 0/C anneal, under high vacuum, contributed to the formation of a very unusual maze morphology and also to a rectangular-step morphology.

  10. Development of a vacuum arc fault current limiter

    SciTech Connect

    Dollinger, R.; Gilmour, A.S. Jr.

    1981-07-01

    The primary purpose of this program was to develop an understanding of the operating principles of the vacuum arc devices under development at the State University of New York at Buffalo for fault current limiting applications. The general operating characteristics are given for two basic vacuum arc devices. One is the Vacuum Arc Fault Current Limiter and the other is the Magnetically Controlled Vacuum Arc Switch. The results of detailed studies of the phenomena occurring with the two devices are described. In particular, the repetitive voltage spiking phenomena that occurs in the Vacuum Arc Fault Current Limiter is treated in substantial detail. The mechanism of the voltage spiking (the repetitive formation and collapse of an anode sheath) is described along with measurements that were made of parameters associated with repetitive spiking. Techniques for enhancing current limiting by enhancing spiking development are discussed. Work on the magnetically controlled vacuum arc switch and the cooperative efforts with the industrial partner (Gould-Brown Boveri) are described.

  11. Physical phenomena disturbing LIBS analysis

    Microsoft Academic Search

    A. Sarzynski; W. Skrzeczanowski; J. Marczak

    2007-01-01

    An influence of some physical phenomena disturbing correct interpretation of LIBS spectra is described in the paper. The following phenomena were investigated: a way of laser beam focusing (power density), laser spark in air, spectral line broadening, apparatus efficiency and resolution, and an influence of those factors on LIBS spectra as well. They are particularly important for quantitative LIBS measurements.

  12. The oxidization behavior and mechanical properties of ultrananocrystalline diamond films at high temperature annealing

    NASA Astrophysics Data System (ADS)

    Huang, Kai; Hu, Xiaojun; Xu, Hui; Shen, Yaogen; Khomich, Alex

    2014-10-01

    Ultrananocrystalline diamond (UNCD) films prepared by hot filament chemical vapor deposition (HFCVD) were annealed at 1000 °C in low degree vacuum under a pressure of 4000 Pa. The correlation between the mechanical and structural properties was investigated to understand the oxidization behavior of UNCD films after high temperature annealing. At the early stage of annealing (?30 min), the amorphous carbon and graphite in grain boundaries are selectively oxidized firstly along the clusters' gaps, with the Young's modulus and hardness decreasing rapidly revealed by nanoindentation results. A special annealing time of ?30-60 min is found to exist as a turning point that the mechanical properties changing trend has a transition, because of the diamond grains starting to be oxidized. With the annealing time increasing to 180 min, the nanoindentation depth increases from ?70 to ?90 nm and the Young's modulus and hardness decrease more slowly with almost keeping constant of ?383 and ?35 GPa, respectively. X-ray photoelectron spectroscopy (XPS) results show that a steady 30-nm-thick oxidized layer has been formed on the top-surface and keeps a balance of the speed between films being oxidized and the carbon oxidation being broken down.

  13. Enhanced annealing of GaAs solar cell radiation damage

    Microsoft Academic Search

    R. Loo; R. C. Knechtli; G. S. Kamath

    1981-01-01

    Solar cells are degraded by radiation damage in space. Investigations have been conducted concerning possibilities for annealing this radiation damage in GaAs solar cells, taking into account the conditions favoring such annealing. It has been found that continuous annealing as well as the combination of injection annealing with thermal annealing can lead to recovery from radiation damage under particularly favorable

  14. The quantum vacuum

    E-print Network

    G. S. Paraoanu

    2014-12-12

    The vacuum is the lowest energy state of a field in a certain region of space. This definition implies that no particles can be present in the vacuum state. In classical physics, the only features of vacuum are those of its geometry. For example, in the general theory of relativity the geometry is a dynamical structure that guides the motion of matter, and, in turn, it is bent and curved by the presence of matter. Other than this, the classical vacuum is a structure void of any physical properties, since classically properties are strictly associated with physical objects such as particles and finite-amplitude fields. The situation is very different in quantum physics. As I will show in this paper, the difference stems from the fact that in quantum physics the properties are not strictly tied to objects. We know for example that physical properties come into existence - as values of observables - only when the object is measured. Thus, quantum physics allows us to detach properties from objects. This has consequences: one does not need pre-existing real objects to create actual properties, and indeed under certain perturbations the quantum vacuum produces observable effects such as energy shifts and creation of particles. An open question is if by necessity the vacuum comes with an embedded geometry, and if it is possible to construct viable physical theories in which geometry is detached from the vacuum.

  15. Boron distribution in silicon after multiple pulse excimer laser annealing

    SciTech Connect

    Monakhov, E.V.; Svensson, B.G.; Linnarsson, M.K.; La Magna, A.; Italia, M.; Privitera, V.; Fortunato, G.; Cuscuna, M.; Mariucci, L. [Department of Physics, Physical Electronics, University of Oslo, P.O. Box 1048, Blindern, N-0316 Oslo (Norway); Royal Institute of Technology, Lab of Materials and Semiconductor Physics, P.O. Box Electrum 229, SE-164 40 Kista (Sweden); CNR-IMM, Stradale Primosole 50, 95121 Catania (Italy); CNR-IFN, Via Cineto Romano 42, 00156 Rome (Italy)

    2005-08-22

    We have studied B redistribution in Si after excimer laser annealing (ELA) with multiple laser pulses. B was implanted with energies of 1 and 10 keV and doses of 1x10{sup 14} and 1x10{sup 15} cm{sup -2}. ELA with the number of pulses from 1 to 100 was performed at room temperature and 450 deg. C in vacuum. Irrespective of the implantation parameters and the ELA conditions used, a pile-up in the B concentration is observed near the maximum melting depth after ten pulses of ELA. Moreover, a detailed study has revealed that B accumulates at the maximum melt depth gradually with the number of ELA pulses. Besides, an increase in the carrier concentration is observed at the maximum melt depth, suggesting electrical activity of the accumulated B. Formation of Si-B complexes and vacancy accumulation during multiple ELA are discussed as possible mechanisms for the B build-up.

  16. Thermophoretic vacuum wand

    DOEpatents

    Klebanoff, Leonard Elliott (San Ramon, CA); Rader, Daniel John (Lafayette, CA)

    2000-01-01

    A thermophoretic vacuum wand that is particularly suited for transporting articles in a cleanroom environment so that potential particle contaminants in the air do not become adhered to the surface of the article is described. The wand includes a housing having a platen with a front surface with suction port(s) through the platen; a vacuum source for applying a negative pressure to the suction port(s); and heating device for the object. Heating the article when it is held by the vacuum wand affords thermophoretic protection that effectively prevents particles in the air from depositing onto the article.

  17. Thermophoretic vacuum wand

    DOEpatents

    Klebanoff, Leonard Elliott (San Ramon, CA); Rader, Daniel John (Lafayette, CA)

    2001-01-01

    A thermophoretic vacuum wand that is particularly suited for transporting articles in a cleanroom environment so that potential particle contaminants in the air do not become adhered to the surface of the article is described. The wand includes a housing having a platen with a front surface with suction port(s) through the platen; a vacuum source for applying a negative pressure to the suction port(s); and heating device for the object. Heating the article when it is held by the vacuum wand affords thermophoretic protection that effectively prevents particles in the air from depositing onto the article.

  18. Evading death by vacuum

    E-print Network

    A. Barroso; P. M. Ferreira; I. P. Ivanov; Rui Santos; João P. Silva

    2013-03-15

    In the Standard Model, the Higgs potential allows only one minimum at tree-level. But the open possibility that there might be two scalar doublets enriches the vacuum structure, allowing for the risk that we might now be in a metastable state, which we dub the panic vacuum. Current experiments at the LHC are probing the Higgs particle predicted as a result of the spontaneous symmetry breaking. Remarkably, in the two Higgs model with a softly broken U(1) symmetry, the LHC experiments already preclude panic vacuum solutions.

  19. Direct and pulsed current annealing of p-MOSFET based dosimeter: the "MOSkin".

    PubMed

    Alshaikh, Sami; Carolan, Martin; Petasecca, Marco; Lerch, Michael; Metcalfe, Peter; Rosenfeld, Anatoly

    2014-06-01

    Contemporary radiation therapy (RT) is complicated and requires sophisticated real-time quality assurance (QA). While 3D real-time dosimetry is most preferable in RT, it is currently not fully realised. A small, easy to use and inexpensive point dosimeter with real-time and in vivo capabilities is an option for routine QA. Such a dosimeter is essential for skin, in vivo or interface dosimetry in phantoms for treatment plan verification. The metal-oxide-semiconductor-field-effect-transistor (MOSFET) detector is one of the best choices for these purposes, however, the MOSFETs sensitivity and its signal stability degrade after essential irradiation which limits its lifespan. The accumulation of positive charge on the gate oxide and the creation of interface traps near the silicon-silicon dioxide layer is the primary physical phenomena responsible for this degradation. The aim of this study is to investigate MOSFET dosimeter recovery using two proposed annealing techniques: direct current (DC) and pulsed current (PC), both based on hot charged carrier injection into the gate oxide of the p-MOSFET dosimeter. The investigated MOSFETs were reused multiple times using an irradiation-annealing cycle. The effect of the current-annealing parameters was investigated for the dosimetric characteristics of the recovered MOSFET dosimeters such as linearity, sensitivity and initial threshold voltage. Both annealing techniques demonstrated excellent results in terms of maintaining a stable response, linearity and sensitivity of the MOSFET dosimeter. However, PC annealing is more preferable than DC annealing as it offers better dose response linearity of the reused MOSFET and has a very short annealing time. PMID:24648245

  20. Biplanar gradient coil design by simulated annealing

    Microsoft Academic Search

    A. M. Peters; R. W. Bowtell

    1994-01-01

    Simulated annealing has been applied to the design of biplanar gradient coils for use in NMR microscopy. This method allows a variety of coil parameters to be considered, such as homogeneity over a specified region of interest (ROI), power dissipation, and efficiency. Chosen parameters are represented in an overall figure of merit which is then minimized by the simulated annealing

  1. Hybrid parallel tempering and simulated annealing method

    Microsoft Academic Search

    Yaohang Li; Vladimir A. Protopopescu; Nikita Arnold; Xinyu Zhang; Andrey Gorin

    2009-01-01

    In this paper, we propose a new hybrid scheme of parallel tempering and simulated annealing (hybrid PT\\/SA). Within the hybrid PT\\/SA scheme, a composite system with multi- ple conformations is evolving in parallel on a temperature ladder with various transition step sizes. The simulated annealing (SA) process uses a cooling scheme to decrease the temperature values in the temperature ladder

  2. Simulated annealing artificial fish swarm algorithm

    Microsoft Academic Search

    Mingyan Jiang; Yongming Cheng

    2010-01-01

    This paper presents a novel stochastic approach called the simulated annealing-artificial fish swarm algorithm (SA-AFSA) for solving some multimodal problems. The proposed algorithm incorporates the simulated annealing (SA) into artificial fish swarm algorithm (AFSA) to improve the performance of the AFSA. The hybrid algorithm has the following features: the hybrid algorithm maintains 1) the strong local searching ability of the

  3. Adaptive simulated annealing (ASA): Lessons learned

    Microsoft Academic Search

    Lester Ingber

    2000-01-01

    Adaptive simulated annealing (ASA) is a global optimization algorithm based on an associated proof that the parameter space can be sampled much more efficiently than by using other previous simulated annealing algorithms. The author's ASA code has been publicly available for over two years. During this time the author has volunteered to help people via e-mail, and the feedback obtained

  4. Circuit partitioning using mean field annealing

    Microsoft Academic Search

    Tevfik Bultan; Cevdet Aykanat

    1995-01-01

    Meanfield annealing (MFA) algorithm, proposed for solving combinatorial optimization problems, combines the characteristics of neural networks and simulated annealing. Previous works on MFA resulted with successful mapping of the algorithm to some classic optimization problems such as traveling salesperson problem, scheduling problem, knapsack problem and graph partitioning problem. In this paper, MFA is formulated for the circuit partitioning problem using

  5. Thermal Stability of RuO2 Thin Films and Effects of Annealing Ambient on Their Reduction Process

    NASA Astrophysics Data System (ADS)

    Kaga, Yukinao; Abe, Yoshio; Sasaki, Midori

    1999-06-01

    RuO2 films prepared by reactive sputtering were annealed in air and vacuum and the changes of their crystal structure, chemical binding state and resistivity were studied.In air, the RuO2 films maintain a rutile structure below 800°C.Crystal grain growth was found above 600°C and the minimum resistivity of 46 µ?cm was obtained at 800°C.The vacuum annealing was conducted with two types of annealing systems, one using an oil diffusion pump and the other using a turbomolecular pump as the main pump.The RuO2 films annealed in the system using the turbomolecular pump were not reduced below 500°C, however, the surface of the films was reduced as low as 200°C in the system using the oil diffusion pump.The difference in the reduction processes was examined on the basis of the thermodynamics of RuO2 and the influence of reducing residual gases in vacuum.

  6. Vacuum mechatronics first international workshop

    SciTech Connect

    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. The temperature dependence of the spin polarization of field emitted electrons from a W-EuS-vacuum junction

    Microsoft Academic Search

    G. Baum; E. Kisker; A. H. Mahan; K. Schröder

    1976-01-01

    We have measured the temperature dependence P(T) of the electron spin polarization of field emitted electrons from a W-EuS-vacuum junction. The shapes of the P(T) curves depend strongly on the annealing temperature of the EuS layer. Annealed at some temperature between 300°C and 600°C the polarization drops to zero at about 16 +\\/- 2 K.

  8. Supermite vacuum interface design

    NASA Astrophysics Data System (ADS)

    Moore, W. B.; Stinnett, R. W.; McDaniel, D. H.

    A new water plastic vacuum interface has been designed for Sandia Laboratory's Supermite (2.8 MV, 2.2 ohm) accelerator. This design was based on the PBFA I vacuum interface. Electrostatic field plots show that in positive polarity the water feed to the PBFA I interface will fail at 2 MV on Supermite. This is confirmed by positive polarity experiments and field plots using the PBFA I style vacuum interface at the Naval Research Labs. Modifications to the water section geometry to increase the water breakdown strength in positive polarity result in equivalent electric field grading at the plastic vacuum interface but allow positive polarity operation at voltages up to 3.1 MV. This is accomplished by incorporating a dielectric field shaper which significantly improves the electric field grading across the insulator.

  9. Vacuum Camera Cooler

    NASA Technical Reports Server (NTRS)

    Laugen, Geoffrey A.

    2011-01-01

    Acquiring cheap, moving video was impossible in a vacuum environment, due to camera overheating. This overheating is brought on by the lack of cooling media in vacuum. A water-jacketed camera cooler enclosure machined and assembled from copper plate and tube has been developed. The camera cooler (see figure) is cup-shaped and cooled by circulating water or nitrogen gas through copper tubing. The camera, a store-bought "spy type," is not designed to work in a vacuum. With some modifications the unit can be thermally connected when mounted in the cup portion of the camera cooler. The thermal conductivity is provided by copper tape between parts of the camera and the cooled enclosure. During initial testing of the demonstration unit, the camera cooler kept the CPU (central processing unit) of this video camera at operating temperature. This development allowed video recording of an in-progress test, within a vacuum environment.

  10. Annealed importance sampling with constant cooling rate

    NASA Astrophysics Data System (ADS)

    Giovannelli, Edoardo; Cardini, Gianni; Gellini, Cristina; Pietraperzia, Giangaetano; Chelli, Riccardo

    2015-02-01

    Annealed importance sampling is a simulation method devised by Neal [Stat. Comput. 11, 125 (2001)] to assign weights to configurations generated by simulated annealing trajectories. In particular, the equilibrium average of a generic physical quantity can be computed by a weighted average exploiting weights and estimates of this quantity associated to the final configurations of the annealed trajectories. Here, we review annealed importance sampling from the perspective of nonequilibrium path-ensemble averages [G. E. Crooks, Phys. Rev. E 61, 2361 (2000)]. The equivalence of Neal's and Crooks' treatments highlights the generality of the method, which goes beyond the mere thermal-based protocols. Furthermore, we show that a temperature schedule based on a constant cooling rate outperforms stepwise cooling schedules and that, for a given elapsed computer time, performances of annealed importance sampling are, in general, improved by increasing the number of intermediate temperatures.

  11. III. Vacuum PumpsIII. Vacuum Pumps Gas transfer

    E-print Network

    Liu, Kai

    : Oil Diffusion PumpB. High Vacuum: Oil Diffusion Pump (Wet, Gas Transfer)(Wet, Gas Transfer, Screw High vacuum Oil diffusion, Turbomolecular, Cryo, Ion Auxiliary Titanium Sublimation, LN2 Liu, UCDIII. Vacuum PumpsIII. Vacuum Pumps Mechanism Gas transfer Gas capture FunctionFunction Roughing

  12. Flow phenomena in rocks: from continuum models to fractals, percolation, cellular automata, and simulated annealing

    Microsoft Academic Search

    Muhammad Sahimi

    1993-01-01

    In this paper, theoretical and experimental approaches to flow, hydrodynamic dispersion, and miscible and immiscible displacement processes in reservoir rocks are reviewed and discussed. Both macroscopically homogeneous and heterogeneous rocks are considered. The latter are characterized by large-scale spatial variations and correlations in their effective properties and include rocks that may be characterized by several distinct degrees of porosity, a

  13. Characterization of nanostructured ZnO thin films deposited through vacuum evaporation

    PubMed Central

    Maldonado, Arturo; Juarez, Héctor; Pacio, Mauricio; Perez, Rene

    2015-01-01

    Summary This work presents a novel technique to deposit ZnO thin films through a metal vacuum evaporation technique using colloidal nanoparticles (average size of 30 nm), which were synthesized by our research group, as source. These thin films had a thickness between 45 and 123 nm as measured by profilometry. XRD patterns of the deposited thin films were obtained. According to the HRSEM micrographs worm-shaped nanostructures are observed in samples annealed at 600 °C and this characteristic disappears as the annealing temperature increases. The films obtained were annealed from 25 to 1000 °C, showing a gradual increase in transmittance spectra up to 85%. The optical band gaps obtained for these films are about 3.22 eV. The PL measurement shows an emission in the red and in the violet region and there is a correlation with the annealing process. PMID:25977868

  14. Physical phenomena disturbing LIBS analysis

    NASA Astrophysics Data System (ADS)

    Sarzy?ski, A.; Skrzeczanowski, W.; Marczak, J.

    2007-07-01

    An influence of some physical phenomena disturbing correct interpretation of LIBS spectra is described in the paper. The following phenomena were investigated: a way of laser beam focusing (power density), laser spark in air, spectral line broadening, apparatus efficiency and resolution, and an influence of those factors on LIBS spectra as well. They are particularly important for quantitative LIBS measurements. The presented measurement results clearly show that the correct elemental identification plays a significant role in artworks dating [5].

  15. Engineering of nanoscale defect patterns in CeO2 nanorods via ex situ and in situ annealing.

    PubMed

    Sakthivel, Tamil Selvan; Reid, David L; Bhatta, Umananda M; Möbus, Günter; Sayle, Dean C; Seal, Sudipta

    2015-03-12

    Single-crystalline ceria nanorods were fabricated using a hydrothermal process and annealed at 325 °C-800 °C. As-synthesized CeO2 nanorods contain a high concentration of defects, such as oxygen vacancies and high lattice strains. Annealing resulted in an improved lattice crystalline quality along with the evolution of novel cavity-shaped defects in the nanorods with polyhedral morphologies and bound by e.g. {111} and {100} (internal) surfaces, confirmed for both air (ex situ) and vacuum (in situ) heating. We postulate that the cavities evolve via agglomeration of vacancies within the as-synthesized nanorods. PMID:25655364

  16. Theory of Quantum Annealing of an Ising Spin Glass

    E-print Network

    Giuseppe E. Santoro; Roman Martonak; Erio Tosatti; Roberto Car

    2002-05-14

    Probing the lowest energy configuration of a complex system by quantum annealing was recently found to be more effective than its classical, thermal counterpart. Comparing classical and quantum Monte Carlo annealing protocols on the random two-dimensional Ising model we confirm the superiority of quantum annealing relative to classical annealing. We also propose a theory of quantum annealing, based on a cascade of Landau-Zener tunneling events. For both classical and quantum annealing, the residual energy after annealing is inversely proportional to a power of the logarithm of the annealing time, but the quantum case has a larger power which makes it faster

  17. Vacuum Energy: Myths and Reality

    Microsoft Academic Search

    2006-01-01

    We discuss the main myths related to the vacuum energy and cosmological\\u000aconstant, such as: ``unbearable lightness of space-time''; the dominating\\u000acontribution of zero point energy of quantum fields to the vacuum energy;\\u000anon-zero vacuum energy of the false vacuum; dependence of the vacuum energy on\\u000athe overall shift of energy; the absolute value of energy only has significance\\u000afor

  18. Separation phenomena in the tritium source and numerical simulations of turbo-molecular pumps

    E-print Network

    Sharipov, Felix

    Separation phenomena in the tritium source and numerical simulations of turbo-molecular pumps Felix In the previous works [1, 2], the results of numerical calculations of tritium flow from the buffer vessel up to the first vacuum system were reported. Two values of the tritium source temperature were considered, i.e. 27

  19. Stellarator helical vacuum vessel

    SciTech Connect

    Yavornik, E.J.

    1983-01-01

    A design study of a stainless steel, heavy wall, helically shaped vacuum torus has been made for use in a proposed Stellarator configuration. The study concerns itself with the shape of the vacuum vessel and the division of the vessel into components that can be machined and welded together into a helical configuration. A complication in the design requires that a circular magnet coil be located at the minor toroidal axis and that this coil be embedded within the periphery of the vacuum vessel. The vacuum vessel has a minor toroidal axis diameter of 4 meters, a 68.6-cm shell diameter, and a 1.9-cm wall thickness. It twists about the minor toroidal axis twice in 360/sup 0/C. (An n value of 2). It is proposed that the unit be made of cylindrical segments with the ends of the cylinders cut at appropriate lengths and angles to form the helix. A mathematical derivation of the dimensions necessary to produce the required shapes of the segments has been made. Also, drawings of the vacuum vessel components have been produced on LANL's CTR CAD/CAM system. The procedure developed can be used for any value of n as dictated by physics requirements.

  20. Vacuum Techniques Lecture Notes

    NSDL National Science Digital Library

    Most modern day experimental research in physical chemistry is performed with the use of some sort of vacuum system. Organic and inorganic chemists are also finding it is essential to conduct synthetic and kinetic work under controlled or reduced pressures. The term "vacuum system" is applied rather broadly, from instrumentation that operates at very low pressures (i.e., below 10-8 torr) to systems that are only pumped down once to remove air and then used to handle gases at moderate pressures (up to and sometimes over one atmosphere). Vacuum systems vary widely in their size and complexity (and expense) depending on the requirements of pumping speed and attainable vacuum. This experiment is designed to illustrate the purpose and use of the basic components found on typical vacuum apparati. The volumes of the isolatable sections of the system will be measured. Also, some of the variables, such as pumping speed, which should be considered in designing such a system, will be investigated.

  1. Critical velocity phenomena and the LTP. [Lunar Transient Phenomena

    NASA Technical Reports Server (NTRS)

    Srnka, L. J.

    1977-01-01

    When the relative velocity between magnetized plasma and neutral gas exceeds a critical value, the gas-plasma interaction is dominated by collective phenomena which rapidly excite and ionize the neutrals. The interaction of the solar wind with a large cloud (between 10 to the 24th and 10 to the 28th power neutrals) vented from the moon should be of this type. Line radiation from such an interaction can yield an apparent lunar surface brightness rivaling reflected sunlight levels over small areas, if the kinetic-energy flow density of the gas is sufficiently high. The aberrated solar-wind flow past the moon would enhance the visibility of such interactions near the lunar sunrise terminator, supporting the statistical studies which indicate that the 'Lunar Transient Phenomena' (anomalous optical phenomena on the moon) are significantly correlated with the position of the terminator on the lunar surface.

  2. Crystal growth behaviour in Au-ZnO nanocomposite under different annealing environments and photoswitchability

    SciTech Connect

    Mishra, Y. K.; Adelung, R. [Functional Nanomaterials, Institute for Materials Science, University of Kiel, Kaiserstrasse 2, 24143 Kiel (Germany); Chakravadhanula, V. S. K.; Hrkac, V.; Kienle, L. [Synthesis and Real Structure, Institute for Materials Science, University of Kiel, Kaiserstrasse 2, 24143 Kiel (Germany); Jebril, S. [Multicomponent Materials, Institute for Materials Science, University of Kiel, Kaiserstrasse 2, 24143 Kiel (Germany); Agarwal, D. C.; Avasthi, D. K. [Inter University Accelerator Centre, Post Box 10502, New Delhi 110067 (India); Mohapatra, S. [University School of Basic and Applied Sciences, GGS Indraprastha University, Dwaraka, New Delhi 110075 (India)

    2012-09-15

    The growth of gold nanoparticles and ZnO nanorods in atom beam co-sputtered Au-ZnO nanocomposite (NC) system by annealing at two different ambient conditions is demonstrated in this work. Annealing in a furnace at 600 Degree-Sign C (air environment) confirmed the formation of ZnO nanorods surrounded with Au nanoparticles. In-situ annealing inside a transmission electron microscope (TEM) led to the formation of gold nanocrystals with different polygonal shapes. TEM micrographs were obtained in real time at intermediate temperatures of 300 Degree-Sign C, 420 Degree-Sign C, and 600 Degree-Sign C under vacuum. The growth mechanisms of Au nanocrystals and ZnO nanorods are discussed in the framework of Au-Zn eutectic and Zn-melting temperatures in vacuum and air, respectively. Current-voltage responses of Au-ZnO NC nanorods in dark as well as under light illumination have been investigated and photoswitching in Au-ZnO NC system is reported. The photoswitching has been discussed in terms of Au-ZnO band-diagram.

  3. Crystal growth behaviour in Au-ZnO nanocomposite under different annealing environments and photoswitchability

    NASA Astrophysics Data System (ADS)

    Mishra, Y. K.; Chakravadhanula, V. S. K.; Hrkac, V.; Jebril, S.; Agarwal, D. C.; Mohapatra, S.; Avasthi, D. K.; Kienle, L.; Adelung, R.

    2012-09-01

    The growth of gold nanoparticles and ZnO nanorods in atom beam co-sputtered Au-ZnO nanocomposite (NC) system by annealing at two different ambient conditions is demonstrated in this work. Annealing in a furnace at 600 °C (air environment) confirmed the formation of ZnO nanorods surrounded with Au nanoparticles. In-situ annealing inside a transmission electron microscope (TEM) led to the formation of gold nanocrystals with different polygonal shapes. TEM micrographs were obtained in real time at intermediate temperatures of 300 °C, 420 °C, and 600 °C under vacuum. The growth mechanisms of Au nanocrystals and ZnO nanorods are discussed in the framework of Au-Zn eutectic and Zn-melting temperatures in vacuum and air, respectively. Current-voltage responses of Au-ZnO NC nanorods in dark as well as under light illumination have been investigated and photoswitching in Au-ZnO NC system is reported. The photoswitching has been discussed in terms of Au-ZnO band-diagram.

  4. Improving Vacuum Cleaners

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Under a Space Act Agreement between the Kirby company and Lewis Research Center, NASA technology was applied to a commercial vacuum cleaner product line. Kirby engineers were interested in advanced operational concepts, such as particle flow behavior and vibration, critical factors to improve vacuum cleaner performance. An evaluation of the company 1994 home care system, the Kirby G4, led to the refinement of the new G5 and future models. Under the cooperative agreement, Kirby had access to Lewis' holography equipment, which added insight into how long a vacuum cleaner fan would perform, as well as advanced computer software that can simulate the flow of air through fans. The collaboration resulted in several successes including fan blade redesign and continuing dialogue on how to improve air-flow traits in various nozzle designs.

  5. Enthalpy relaxation and annealing effect in polystyrene

    NASA Astrophysics Data System (ADS)

    Sakatsuji, Waki; Konishi, Takashi; Miyamoto, Yoshihisa

    2013-07-01

    The effects of thermal history on the enthalpy relaxation in polystyrene are studied by differential scanning calorimetry. The temperature dependence of the specific heat in the liquid and the glassy states, that of relaxation time, and the exponent of the Kohlrausch-Williams-Watts function are determined by measurements of the thermal response against sinusoidal temperature variation. A phenomenological model equation previously proposed to interpret the memory effect in the frozen state is applied to the enthalpy relaxation and the evolution of entropy under a given thermal history is calculated. The annealing below the glass transition temperature produces two effects on enthalpy relaxation: the decay of excess entropy with annealing time in the early stage of annealing and the increase in relaxation time due to physical aging in the later stage. The crossover of these effects is reflected in the variation of temperature of the maximum specific heat observed in the heating process after annealing and cooling.

  6. Annealing of single lamella nanoparticles of polyethylene

    E-print Network

    Christophe N. Rochette; Sabine Rosenfeldt; Katja Henzler; Frank Polzer; Matthias Ballauff; Qiong Tong; Stefan Mecking; Markus Drechsler; Theyencheri Narayanan; Ludger Harnau

    2011-07-05

    We study the change of the size and structure of freely suspended single lamella nanoparticles of polyethylene during thermal annealing in aqueous solutions. Using small-angle x-ray scattering and cryogenic transmission electron microscopy, it is shown that a doubling of the crystalline lamella sandwiched between two amorphous polymer layers is obtained by annealing the nanoparticles at 125 C. This thickening of the crystalline lamella can be understood in terms of an unlooping of polymer chains within a single nanoparticle. In addition a variation of the annealing temperature from 90 C to 115 C demonstrates that the inverse of the crystalline lamellar thickness increases linearly with the annealing temperatures leading to a recrystallization line in a Gibbs-Thomson graph. Since the nanoparticles consist of about only eight polymer chains, they can be considered as a ideal candidates for the experimental realization of equilibrium polymer crystals.

  7. Enthalpy relaxation and annealing effect in polystyrene.

    PubMed

    Sakatsuji, Waki; Konishi, Takashi; Miyamoto, Yoshihisa

    2013-07-01

    The effects of thermal history on the enthalpy relaxation in polystyrene are studied by differential scanning calorimetry. The temperature dependence of the specific heat in the liquid and the glassy states, that of relaxation time, and the exponent of the Kohlrausch-Williams-Watts function are determined by measurements of the thermal response against sinusoidal temperature variation. A phenomenological model equation previously proposed to interpret the memory effect in the frozen state is applied to the enthalpy relaxation and the evolution of entropy under a given thermal history is calculated. The annealing below the glass transition temperature produces two effects on enthalpy relaxation: the decay of excess entropy with annealing time in the early stage of annealing and the increase in relaxation time due to physical aging in the later stage. The crossover of these effects is reflected in the variation of temperature of the maximum specific heat observed in the heating process after annealing and cooling. PMID:23944484

  8. INVESTIGATION Recombination and Annealing Pathways Compete

    E-print Network

    Roth, John R.

    such that different rrn loci can provide single-strand rrn sequences that lack the RecA coating that normally inhibits duplication by recombination and annealing pathways may reflect a limiting economy of gaps and breaks arising

  9. Annealing behavior of high permeability amorphous alloys

    SciTech Connect

    Rabenberg, L.

    1980-06-01

    Effects of low temperature annealing on the magnetic properties of the amorphous alloy Co/sub 71/ /sub 4/Fe/sub 4/ /sub 6/Si/sub 9/ /sub 6/B/sub 14/ /sub 4/ were investigated. Annealing this alloy below 400/sup 0/C results in magnetic hardening; annealing above 400/sup 0/C but below the crystallization temperature results in magnetic softening. Above the crystallization temperature the alloy hardens drastically and irreversibly. Conventional and high resolution transmission electron microscopy were used to show that the magnetic property changes at low temperatures occur while the alloy is truly amorphous. By imaging the magnetic microstructures, Lorentz electron microscopy has been able to detect the presence of microscopic inhomogeneities in this alloy. The low temperature annealing behavior of this alloy has been explained in terms of atomic pair ordering in the presence of the internal molecular field. Lorentz electron microscopy has been used to confirm this explanation.

  10. Vacuum Arc Ion Sources

    E-print Network

    Brown, I

    2013-01-01

    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.

  11. Spacecraft thermal vacuum testing

    NASA Technical Reports Server (NTRS)

    Elam, B. F.; Lancaster, L. D.

    1972-01-01

    An approach for developing a general thermal vacuum test program philosophy is discussed. Guidelines are established that will assist the project engineer in relating the risk associated with flying any spacecraft to its test program. Computerized techniques can be used to help ascertain these guidelines, which relate the risk to the level of test (component, subsystem, etc), as well as to the type of test (development, qualification, etc). The interrelationship between the test program and the analytical effort is also discussed. The Skylab Apollo telescope mount general thermal vacuum test program, including test schedules, instrumentation, and test results is also discussed.

  12. The microstructural response of mill-annealed and solution-annealed INCONEL 600 to heat treatment

    Microsoft Academic Search

    Ernest L. Hall; Clyde L. Briant

    1985-01-01

    Samples of INCONEL* 600 were examined in the mill-annealed and solution-annealed states, and after isothermal annealing at\\u000a 400 °C and 650 °C. The corrosion behavior of the samples was examined, analytical electron microscopy was used to determine\\u000a the microstructures present and the chemistry of grain boundaries, and Auger electron spectroscopy was used to measure grain\\u000a boundary segregation. Samples of different

  13. K-130 Cyclotron vacuum system

    NASA Astrophysics Data System (ADS)

    Yadav, R. C.; Bhattacharya, S.; Bhole, R. B.; Roy, Anindya; Pal, Sarbajit; Mallik, C.; Bhandari, R. K.

    2012-11-01

    The vacuum system for K-130 cyclotron has been operational since 1977. It consists of two sub-systems, main vacuum system and beam line vacuum system. The main vacuum system is designed to achieve and maintain vacuum of about 1 × 10-6 mbar inside the 23 m3 volume of acceleration chamber comprising the Resonator tank and the Dee tank. The beam line vacuum system is required for transporting the extracted beam with minimum loss. These vacuum systems consist of diffusion pumps backed by mechanical pumps like roots and rotary pumps. The large vacuum pumps and valves of the cyclotron vacuum system were operational for more than twenty five years. In recent times, problems of frequent failures and maintenance were occurring due to aging and lack of appropriate spares. Hence, modernisation of the vacuum systems was taken up in order to ensure a stable high voltage for radio frequency system and the extraction system. This is required for efficient acceleration and transportation of high intensity ion beam. The vacuum systems have been upgraded by replacing several pumps, valves, gauges and freon units. The relay based control system for main vacuum system has also been replaced by PLC based state of the art control system. The upgraded control system enables inclusion of additional operational logics and safety interlocks into the system. The paper presents the details of the vacuum system and describes the modifications carried out for improving the performance and reliability of the vacuum system.

  14. The vacuum interpretation of quantum mechanics and the vacuum universe

    E-print Network

    Ding-Yu Chung

    2001-10-27

    Quantum mechanics is interpreted by the adjacent vacuum that behaves as a virtual particle to be absorbed and emitted by its matter. As described in the vacuum universe model, the adjacent vacuum is derived from the pre-inflationary universe in which the pre-adjacent vacuum is absorbed by the pre-matter. This absorbed pre-adjacent vacuum is emitted to become the added space for the inflation in the inflationary universe whose space-time is separated from the pre-inflationary universe. This added space is the adjacent vacuum. The absorption of the adjacent vacuum as the added space results in the adjacent zero space (no space), Quantum mechanics is the interaction between matter and the three different types of vacuum: the adjacent vacuum, the adjacent zero space, and the empty space. The absorption of the adjacent vacuum results in the empty space superimposed with the adjacent zero space, confining the matter in the form of particle. When the absorbed vacuum is emitted, the adjacent vacuum can be anywhere instantly in the empty space superimposed with the adjacent zero space where any point can be the starting point (zero point) of space-time. Consequently, the matter that expands into the adjacent vacuum has the probability to be anywhere instantly in the form of wavefunction. In the vacuum universe model, the universe not only gains its existence from the vacuum but also fattens itself with the vacuum. During the inflation, the adjacent vacuum also generates the periodic table of elementary particles to account for all elementary particles and their masses in a good agreement with the observed values.

  15. Polycrystalline silicon resistor trimming by laser annealing 

    E-print Network

    Crowley, Robert Terrence

    1989-01-01

    wavelengths was used to change the resistance of polysilicon resistors by laser annealing. Polysilicon films with a thickness of 0. 5 pm were deposited on 0. 5 pm of silicon dioxide and implanted with boron at a dose of 5. 0 x 10 cm . Laser annealing... that the concentration of boron or phosphorous dopants in the polysilicon was proportional to the concentration of the dopant atoms in the vapor. Carrier concentration was determined using Hall measurements. The carrier concentration indicates the amount...

  16. Quantum annealing in a kinetically constrained system

    Microsoft Academic Search

    Arnab Das; Bikas K. Chakrabarti; Robin B. Stinhcombe

    2005-01-01

    Classical and quantum annealing is discussed for a kinetically constrained\\u000achain of $N$ non-interacting asymmetric double wells, represented by Ising\\u000aspins in a longitudinal field $h$. It is shown that in certain cases, where the\\u000akinetic constraints may arise from infinitely high but vanishingly narrow\\u000abarriers appearing in the relaxation path of the system, quantum annealing\\u000aexploiting the quantum-mechanical penetration

  17. Annealing behavior of electroplated permalloy thin films

    Microsoft Academic Search

    R. L. Anderson; A. Gangulee; L. T. Romankiw

    1973-01-01

    The isochronal annealing behavior of electroplated 1.2 ?m Ni-Fe thin films containing nominally 80 wt% Ni, in the temperature\\u000a range from 373? to 773?K, and with a magnetic field parallel to the easy axis of the films, was investigated through measurements\\u000a of the films’ structural, magnetic and electrical properties. The effects of annealing could be described in terms of two

  18. Annealing behavior of electroplated permalloy thin films

    Microsoft Academic Search

    R. L. Anderson; A. Gangulee; L. T. Romankiw

    1973-01-01

    The isochronal annealing behavior of electroplated 1.2 µm Ni-Fe thin films containing nominally 80 wt% Ni, in the temperature range from 373° to 773°K, and with a magnetic field parallel to the easy axis of the films, was investigated through measurements of the films' structural, magnetic and electrical properties. The effects of annealing could be described in terms of two

  19. Mirowave annealing of silicon nitride materials

    SciTech Connect

    Kiggans, J.O. Jr.; Montgomery, F.C.; Tiegs, T.N. [and others] [and others

    1997-08-01

    Dense silicon nitride-based ceramics were microwave annealed to determine if microwave heating offers advantages over conventional heating for the enhancement of the high temperature creep resistance. Gas pressure sintered silicon nitride (GPS-SN) and sintered reaction-bonded silicon nitride (SRBSN) were heated in microwave or graphite element furnaces at 1150{degrees}C and 1600{degrees}C. Annealed materials were characterized for the room and high temperature flexural strengths, room temperature fracture toughness values, and high temperature creep properties. In addition, SEM analyses were performed to study grain growth and other microstructural changes. The results of this study showed that both types of furnace anneals at 1150{degrees}C lowered the room temperature strength and toughness values of both SRBSN and GPS-SN materials; however, the anneal treatments at 1600{degrees}C had little effect on the room temperature properties. Both the SRBSN and GPS-SN control and annealed samples had reduced high temperature fast fracture strengths, when compared to the room temperature strengths. Creep tests at 1200{degrees}C indicated that both the SRBSN and the GPS-SN materials that were annealed by microwave heating at I 150{degrees}C for 20 h showed enhanced creep resistance, when compared to unheated controls and conventionally heated materials. No qualitative differences were seen in the microstructures of the SRBSN and the GPS-SN materials which could account for the differences in the creep properties of the annealed materials. Additional experimental work is in progress to further understand the mechanisms for the enhanced creep properties of silicon nitride materials annealed by microwave heating.

  20. Annealed CVD molybdenum thin film surface

    DOEpatents

    Carver, Gary E. (Tucson, AZ); Seraphin, Bernhard O. (Tucson, AZ)

    1984-01-01

    Molybdenum thin films deposited by pyrolytic decomposition of Mo(CO).sub.6 attain, after anneal in a reducing atmosphere at temperatures greater than 700.degree. C., infrared reflectance values greater than reflectance of supersmooth bulk molybdenum. Black molybdenum films deposited under oxidizing conditions and annealed, when covered with an anti-reflecting coating, approach the ideal solar collector characteristic of visible light absorber and infrared energy reflector.

  1. The Theory and Practice of Simulated Annealing

    Microsoft Academic Search

    Darrall Henderson; Sheldon H. Jacobson; Alan Johnson

    Simulated annealing is a popular local search meta-heuristic used to address discrete and, to a lesser extent, continuous optimization problems. The key feature of simulated annealing is that it provides a means to escape local optima by allowing hill-climbing moves (i.e., moves which worsen the objective function value) in hopes of finding a global optimum. A brief history of simulated

  2. Laser spike annealing for advanced CMOS devices

    Microsoft Academic Search

    Yun Wang; Shaoyin Chen; Michael Shen; Xiaoru Wang; Senquan Zhou; Jeff Hebb; David Owen

    2008-01-01

    The introduction of new materials in recent years puts more stringent requirements on thermal budget management. For example, high Ge concentration in e-SiGe used for strain engineering makes wafers prone to thermal plastic deformation which limits the maximum annealing temperature. In this paper, we will explore ways to expand the process window using sub-millisecond laser spike annealing. Focus will be

  3. Comparative study of the performance of quantum annealing and simulated annealing

    NASA Astrophysics Data System (ADS)

    Nishimori, Hidetoshi; Tsuda, Junichi; Knysh, Sergey

    2015-01-01

    Relations of simulated annealing and quantum annealing are studied by a mapping from the transition matrix of classical Markovian dynamics of the Ising model to a quantum Hamiltonian and vice versa. It is shown that these two operators, the transition matrix and the Hamiltonian, share the eigenvalue spectrum. Thus, if simulated annealing with slow temperature change does not encounter a difficulty caused by an exponentially long relaxation time at a first-order phase transition, the same is true for the corresponding process of quantum annealing in the adiabatic limit. One of the important differences between the classical-to-quantum mapping and the converse quantum-to-classical mapping is that the Markovian dynamics of a short-range Ising model is mapped to a short-range quantum system, but the converse mapping from a short-range quantum system to a classical one results in long-range interactions. This leads to a difference in efficiencies that simulated annealing can be efficiently simulated by quantum annealing but the converse is not necessarily true. We conclude that quantum annealing is easier to implement and is more flexible than simulated annealing. We also point out that the present mapping can be extended to accommodate explicit time dependence of temperature, which is used to justify the quantum-mechanical analysis of simulated annealing by Somma, Batista, and Ortiz. Additionally, an alternative method to solve the nonequilibrium dynamics of the one-dimensional Ising model is provided through the classical-to-quantum mapping.

  4. Transport Phenomena and Materials Processing

    NASA Astrophysics Data System (ADS)

    Kou, Sindo

    1996-10-01

    An extremely useful guide to the theory and applications of transport phenomena in materials processing This book defines the unique role that transport phenomena play in materials processing and offers a graphic, comprehensive treatment unlike any other book on the subject. The two parts of the text are, in fact, two useful books. Part I is a very readable introduction to fluid flow, heat transfer, and mass transfer for materials engineers and anyone not yet thoroughly familiar with the subject. It includes governing equations and boundary conditions particularly useful for studying materials processing. For mechanical and chemical engineers, and anyone already familiar with transport phenomena, Part II covers the many specific applications to materials processing, including a brief description of various materials processing technologies. Readable and unencumbered by mathematical manipulations (most of which are allocated to the appendixes), this book is also a useful text for upper-level undergraduate and graduate-level courses in materials, mechanical, and chemical engineering. It includes hundreds of photographs of materials processing in action, single and composite figures of computer simulation, handy charts for problem solving, and more. Transport Phenomena and Materials Processing: * Describes eight key materials processing technologies, including crystal growth, casting, welding, powder and fiber processing, bulk and surface heat treating, and semiconductor device fabrication * Covers the latest advances in the field, including recent results of computer simulation and flow visualization * Presents special boundary conditions for transport phenomena in materials processing * Includes charts that summarize commonly encountered boundary conditions and step-by-step procedures for problem solving * Offers a unique derivation of governing equations that leads to both overall and differential balance equations * Provides a list of publicly available computer programs and publications relevant to transport phenomena in materials processing

  5. Effect of annealing on structural and optical properties of diamond-like nanocomposite thin films

    NASA Astrophysics Data System (ADS)

    Jana, Sukhendu; Das, Sayan; De, Debasish; Gangopadhyay, Utpal; Ghosh, Prajit; Mondal, Anup

    2014-03-01

    The annealing effect on structural and optical properties of the Diamond-like Nanocomposite (DLN) thin film deposited on glass substrate by Plasma Assisted Chemical Vapor Deposition (PACVD) method has been investigated. The films were annealed at temperature ranging from 300 to 600 °C, with 100 °C interval for 9 minutes by rapid thermal process (RTP) under vacuum. The structural changes of the annealed films have been studied using Fourier transform infrared spectroscopy (FTIR), Raman spectroscopy, Scanning Electron Microscope (SEM), and optical parameters have been determined using transmittance and reflectance spectra in UV-UIS-NIR range. The result shows that the refractive index increases gradually from 1.79 to 2.84 with annealing temperature due to out-diffusion of H by breaking Si-H and C-H bond leads to Si-C bond, i.e. more cross linking structure. In higher temperature range, graphitization also enhanced the refractive index. However, the optical band gap at up to 400 °C initially increases from 3.05 to 3.20 eV and then decreases due to graphitization. The film has a great potential to be used as anti-reflection coating (ARC) on silicon-based solar cell.

  6. The local crystallization in nanoscale diamond-like carbon films during annealing

    NASA Astrophysics Data System (ADS)

    Kolpakov, A. Ya.; Poplavsky, A. I.; Galkina, M. E.; Manokhin, S. S.; Gerus, J. V.

    2014-12-01

    The local crystallization during annealing at 600 °C in nanoscale diamond-like carbon coatings films grown by pulsed vacuum-arc deposition method was observed using modern techniques of high-resolution transmission electron microscopy. The crystallites formed by annealing have a face-centred cubic crystal structure and grow in the direction [ 0 1 ¯ 1 ¯ ] as a normal to the film surface. The number and size of the crystallites depend on the initial values of the intrinsic stresses before annealing, which in turn depend on the conditions of film growth. The sizes of crystallites are 10 nm for films with initial compressive stresses of 3 GPa and 17 nm for films with initial compressive stresses of 12 GPa. Areas of local crystallization arising during annealing have a structure different from the graphite. Additionally, the investigation results of the structure of nanoscale diamond-like carbon coatings films using Raman spectroscopy method are presented, which are consistent with the transmission electron microscopy research results.

  7. Post-deformational annealing of calcite rocks

    NASA Astrophysics Data System (ADS)

    Barnhoorn, Auke; Bystricky, Misha; Burlini, Luigi; Kunze, Karsten

    2005-07-01

    The evolution of microstructure and crystallographic preferred orientation (CPO) during post-deformational annealing was studied on three calcite rock types differing in purity and grain size: Carrara marble (98% calcite, mean grain size of 115 ?m), Solnhofen limestone (96%, 5 ?m) and synthetic calcite aggregates (99%, 7 ?m). Samples were first deformed in torsion at 727 °C at a shear strain rate of 3 × 10 - 4 s - 1 to a shear strain of 5 and subsequently heat-treated at 727 °C for various durations between 0 and 24 h. Microstructures and CPOs were analysed by optical microscopy, image analysis and electron backscatter diffraction (EBSD). All rock types deformed in the dislocation creep field at the same applied conditions, but their microstructures and CPOs after deformation and after annealing differed depending on starting grain size and material composition. In Carrara marble and in the synthetic calcite aggregate, a strong CPO developed during deformation accompanied by dynamic recrystallisation with significant changes in grain size. During annealing, widespread grain growth and subtle changes of CPO occurred, and equilibrated foam microstructures were approached after long annealing times. The CPO is the only feature in annealed samples indicating an earlier deformation phase, although it is not always identical to the CPO formed during deformation. In the more impure Solnhofen limestone, secondary phases on grain boundaries suppressed grain boundary mobility and prevented both the formation of a recrystallisation CPO during deformation and grain size modification during deformation and annealing.

  8. Halogen and Mercury Lamp Annealing of Arsenic Implanted into Silicon

    Microsoft Academic Search

    Katsuhiro Yokota; Kenji Muta; Masatoshi Kimura; Susumu Tamura; Shinji Ishihara; Itsuro Kimura

    1987-01-01

    As implanted Si was annealed using halogen and mercury lamps whose lights primarily have, respectively, infrared and ultraviolet regions. Annealing time necessary for fully electrically activating the implanted As in the mercury lamp annealing was shorter than that in the halogen lamp annealing, when the light emitted from the two lamps was of the same intensity. This was due to

  9. Proton damage annealing kinetics in silicon solar cells

    NASA Astrophysics Data System (ADS)

    Horne, W. E.; Arimura, I.; Day, A. C.

    1980-07-01

    Proton damage annealing as a method for prolonging the life of solar power systems in space is discussed. Variables are minimized and fundamental characteristics of proton damage annealing are considered. The usefulness of annealing for prolonging space missions is evaluated. A preliminary determination of optimum annealing conditions is made, and base data provided for more detailed research programs.

  10. Influence of in-situ annealing ambient on p-type conduction in dual ion beam sputtered Sb-doped ZnO thin films

    SciTech Connect

    Pandey, Sushil Kumar; Kumar Pandey, Saurabh; Awasthi, Vishnu; Mukherjee, Shaibal [Hybrid Nanodevice Research Group (HNRG), Discipline of Electrical Engineering, Indian Institute of Technology, Indore 453441 (India)] [Hybrid Nanodevice Research Group (HNRG), Discipline of Electrical Engineering, Indian Institute of Technology, Indore 453441 (India); Gupta, M.; Deshpande, U. P. [University Grants Commission Department of Atomic Energy (UGC DAE) Consortium for Scientific Research, Indore (India)] [University Grants Commission Department of Atomic Energy (UGC DAE) Consortium for Scientific Research, Indore (India)

    2013-08-12

    Sb-doped ZnO (SZO) films were deposited on c-plane sapphire substrates by dual ion beam sputtering deposition system and subsequently annealed in-situ in vacuum and in various proportions of O{sub 2}/(O{sub 2} + N{sub 2})% from 0% (N{sub 2}) to 100% (O{sub 2}). Hall measurements established all SZO films were p-type, as was also confirmed by typical diode-like rectifying current-voltage characteristics from p-ZnO/n-ZnO homojunction. SZO films annealed in O{sub 2} ambient exhibited higher hole concentration as compared with films annealed in vacuum or N{sub 2} ambient. X-ray photoelectron spectroscopic analysis confirmed that Sb{sup 5+} states were more preferable in comparison to Sb{sup 3+} states for acceptor-like Sb{sub Zn}-2V{sub Zn} complex formation in SZO films.

  11. Influence of annealing ambient on the structure, photoluminescence and photocatalytic activity of low temperature grown ZnO nanowires

    NASA Astrophysics Data System (ADS)

    Niu, Hongru; Zhao, Xiaoru; Duan, Libing; Wang, Yajun; Wang, Fenggui; Ali, Amjed; Liu, Ruidi

    2015-07-01

    ZnO nanowires were synthesized via a low-temperature (90 °C) hydrothermal route on glass substrates pre-deposited with a ZnO seed layer. The influence of different annealing ambient conditions (air or vacuum) on the structure, photoluminescence and photocatalytic activity of ZnO nanowires was investigated by Raman spectroscopy, X-ray diffraction, photoluminescence (PL) and photochemical reactions etc. It was found that there existed graphitic carbons on the surfaces of ZnO nanowires after vacuum annealing. The PL intensity of ZnO nanowires with the graphitic carbons was significantly reduced while the photocatalytic activity was enhanced, indicating that the graphitic carbons could decrease the recombination probability of photo-induced carriers.

  12. The vacuum conservation theorem

    E-print Network

    E. Minguzzi

    2015-02-28

    A version of the vacuum conservation theorem is proved which does not assume the existence of a time function nor demands stronger properties than the dominant energy condition. However, it is shown that a stronger stable version plays a role in the study of compact Cauchy horizons.

  13. Langmuir vacuum and superconductivity

    SciTech Connect

    Veklenko, B. A. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)

    2012-06-15

    It is shown that, in the 'jelly' model of cold electron-ion plasma, the interaction between electrons and the quantum electromagnetic vacuum of Langmuir waves involves plasma superconductivity with an energy gap proportional to the energy of the Langmuir quantum.

  14. Vacuum insulator coating development

    Microsoft Academic Search

    I. S. Roth; P. S. Sincerny; L. Mandelcorn; M. Mendelsohn; D. Smith; T. G. Engel; L. Schlitt; C. M. Cooke

    1997-01-01

    The authors discuss the electrical and mechanical requirements for vacuum insulators in high peak power generators. To increase the lifetime of these insulators, they have developed a coating called Dendresist. This coating has extended the insulator lifetime on the PITHON, DM2, CASINO, and Double-EAGLE pulsed power generators. They describe its development, and compare its electrical and mechanical strength to that

  15. Vacuum Kundt waves

    NASA Astrophysics Data System (ADS)

    McNutt, David; Milson, Robert; Coley, Alan

    2013-03-01

    We discuss the invariant classification of vacuum Kundt waves using the Cartan-Karlhede algorithm and determine the upper bound on the number of iterations of the Karlhede algorithm to classify the vacuum Kundt waves (Collins (1991 Class. Quantum Grav. 8 1859-69), Machado Ramos (1996 Class. Quantum Grav. 13 1589)). By choosing a particular coordinate system we partially construct the canonical coframe used in the classification to study the functional dependence of the invariants arising at each iteration of the algorithm. We provide a new upper bound, q ? 4, and show that this bound is sharp by analyzing the subclass of Kundt waves with invariant count beginning with (0, 1,…) to show that the class with invariant count (0, 1, 3, 4, 4) exists. This class of vacuum Kundt waves is shown to be unique as the only set of metrics requiring the fourth covariant derivatives of the curvature. We conclude with an invariant classification of the vacuum Kundt waves using a suite of invariants.

  16. Safety of Minkowski Vacuum

    E-print Network

    Gia Dvali

    2011-07-05

    We give a simple argument suggesting that in a consistent quantum field theory tunneling from Minkowski to a lower energy vacuum must be impossible. Theories that allow for such a tunneling also allow for localized states of negative mass, and therefore, should be inconsistent.

  17. What is vacuum?

    Microsoft Academic Search

    Peter Rowlands

    2008-01-01

    Vacuum can be defined with exact mathematical precision as the state which remains when a fermion, with all its special characteristics, is created out of absolutely nothing. The definition leads to a special form of relativistic quantum mechanics, which only requires the construction of a creation operator. This form of quantum mechanics is especially powerful for analytic calculation, at the

  18. Vacuum arc deposition devices

    SciTech Connect

    Boxman, R.L.; Zhitomirsky, V.N. [Electrical Discharge and Plasma Laboratory, Faculty of Engineering, Tel Aviv University, P.O. Box 39040, Tel Aviv 69978 (Israel)

    2006-02-15

    The vacuum arc is a high-current, low-voltage electrical discharge which produces a plasma consisting of vaporized and ionized electrode material. In the most common cathodic arc deposition systems, the arc concentrates at minute cathode spots on the cathode surface and the plasma is emitted as a hypersonic jet, with some degree of contamination by molten droplets [known as macroparticles (MPs)] of the cathode material. In vacuum arc deposition systems, the location and motion of the cathode spots are confined to desired surfaces by an applied magnetic field and shields around undesired surfaces. Substrates are mounted on a holder so that they intercept some portion of the plasma jet. The substrate often provides for negative bias to control the energy of depositing ions and heating or cooling to control the substrate temperature. In some systems, a magnetic field is used to guide the plasma around an obstacle which blocks the MPs. These elements are integrated with a deposition chamber, cooling, vacuum gauges and pumps, and power supplies to produce a vacuum arc deposition system.

  19. Nonlinear Oscillators Vacuum Squeezing

    E-print Network

    Haviland, David

    dz mtF dt dz mzzk =++ =+ --- Classical Physics: The Driven Damped Harmonic Oscillator - a modelNonlinear Oscillators and Vacuum Squeezing David Haviland Nanosturcture Physics, Dept. Applied #12;Splitting of Cavity Resonance Now consider damping: excitation is ½ photon, ½ atom decay rate: 2

  20. Decoherence and Vacuum Fluctuations

    Microsoft Academic Search

    L. H. Ford

    1995-01-01

    The interference pattern of coherent electrons is effected by coupling to the quantized electromagnetic field. The amplitudes of the interference maxima are changed by a factor which depends upon a double line integral of the photon two-point function around the closed path of the electrons. The interference pattern is sensitive to shifts in the vacuum fluctuations in regions from which

  1. Light-front vacuum

    NASA Astrophysics Data System (ADS)

    Herrmann, Marc; Polyzou, W. N.

    2015-04-01

    The purpose of this work is to understand the relation between the trivial vacuum in light-front field theory and the nontrivial vacuum in canonical representations of quantum field theory and the role of zero-modes in this relation. The role of the underlying field algebra in the definition of the vacuum is exploited to understand these relations. The trivial vacuum defined by an annihilation operator defines a linear functional on the algebra of fields restricted to a light front. This is extended to a linear functional on the algebra of local fields. The extension defines a unitary mapping between the physical representation of the local algebra and a sub-algebra of the light-front Fock algebra. The dynamics appears in the mapping and the structure of the sub-algebra. This correspondence provides a formulation of locality and Poincaré invariance on the light-front Fock space. Zero modes do not appear in the final mapping, but may be needed in the construction of the mapping using a local Lagrangian.

  2. The vacuum conservation theorem

    NASA Astrophysics Data System (ADS)

    Minguzzi, E.

    2015-03-01

    A version of the vacuum conservation theorem is proved which does not assume the existence of a time function nor demands stronger properties than the dominant energy condition. However, it is shown that a stronger stable version plays a role in the study of compact Cauchy horizons.

  3. The quantum vacuum

    E-print Network

    Paraoanu, G S

    2014-01-01

    The vacuum is the lowest energy state of a field in a certain region of space. This definition implies that no particles can be present in the vacuum state. In classical physics, the only features of vacuum are those of its geometry. For example, in the general theory of relativity the geometry is a dynamical structure that guides the motion of matter, and, in turn, it is bent and curved by the presence of matter. Other than this, the classical vacuum is a structure void of any physical properties, since classically properties are strictly associated with physical objects such as particles and finite-amplitude fields. The situation is very different in quantum physics. As I will show in this paper, the difference stems form the fact that in quantum physics the properties are not strictly tied to objects. We know for example that physical properties come into existence - as values of observables - only when the object is measured. Thus, quantum physics allows us to detach properties from objects. This has cons...

  4. Vacuum configurations for superstrings

    Microsoft Academic Search

    P. Candelas; Gary T. Horowitz; Andrew Strominger; Edward Witten

    1985-01-01

    We study candidate vacuum configurations in ten-dimensional O(32) and E8 × E8 supergravity and superstring theory that have unbroken N = 1 supersymmetry in four dimensions. This condition permits only a few possibilities, all of which have vanishing cosmological constant. In the E8 × E8 case, one of these possibilities leads to a model that in four dimensions has an

  5. Enhanced annealing of GaAs solar cell radiation damage

    NASA Technical Reports Server (NTRS)

    Loo, R.; Knechtli, R. C.; Kamath, G. S.

    1981-01-01

    Solar cells are degraded by radiation damage in space. Investigations have been conducted concerning possibilities for annealing this radiation damage in GaAs solar cells, taking into account the conditions favoring such annealing. It has been found that continuous annealing as well as the combination of injection annealing with thermal annealing can lead to recovery from radiation damage under particularly favorable conditions in GaAs solar cells. The damage caused by both electrons and protons in GaAs solar cells can be substantially reduced by annealing at temperatures as low as 150 C, under appropriate conditions. This possibility makes the GaAs solar cells especially attractive for long space missions, or for missions in severe radiation environments. Attention is given to results concerning periodic thermal annealing, continuous annealing, and injection annealing combined with thermal annealing.

  6. Vacuum C-metric and the Gravitational Stark Effect

    E-print Network

    Donato Bini; Christian Cherubini; Bahram Mashhoon

    2004-05-27

    We study the vacuum C-metric and its physical interpretation in terms of the exterior spacetime of a uniformly accelerating spherically - symmetric gravitational source. Wave phenomena on the linearized C-metric background are investigated. It is shown that the scalar perturbations of the linearized C-metric correspond to the gravitational Stark effect. This effect is studied in connection with the Pioneer anomaly.

  7. Long-term microstructural stability of oxide-dispersion strengthened Eurofer steel annealed at 800 °C

    NASA Astrophysics Data System (ADS)

    Zilnyk, K. D.; Sandim, H. R. Z.; Bolmaro, R. E.; Lindau, R.; Möslang, A.; Kostka, A.; Raabe, D.

    2014-05-01

    Oxide-dispersion strengthened ferritic martensitic steels such as ODS-Eurofer grade are good candidates for structural applications in future fusion power reactors. Long-term annealing treatments in vacuum were carried out in cold-rolled samples (80% reduction in thickness) from 1 h up to 4320 h (6 months) at 800 °C, i.e. the maximum temperature in the ferritic phase field, to follow its softening behavior. The microstructural stability of this steel was mapped using several characterization techniques including scanning electron microscopy, transmission electron microscopy, electron backscatter diffraction, Vickers microhardness testing, X-ray diffraction texture measurements, low-temperature electrical resistivity, and magnetic coercive field measurements. ODS-Eurofer steel displays good microstructural stability. Discontinuous recrystallization occurs at the early stages of annealing resulting in a low volume fraction of recrystallized grains. Extended recovery is the predominant softening mechanism at this temperature for longer times.

  8. A general model for vacuum condensates and vacuum diffusive coatings

    Microsoft Academic Search

    RI Shishkov; EM Lisichkova

    1995-01-01

    The paper suggests a general model for the classification of metal coatings obtained in vacuum. The model gives the thickness, the bond character and the bond to the coated substrate, depending on : temperature, forming time and condensation rate. The coatings have been classified in two basic groups : vacuum condensates and vacuum diffusive coatings, separated by a layer zone

  9. Demonstrations with a Vacuum: Old Demonstrations for New Vacuum Pumps.

    ERIC Educational Resources Information Center

    Greenslade, Thomas B., Jr.

    1989-01-01

    Explains mechanisms of 19th-century vacuum pumps. Describes demonstrations using the pump including guinea and feather tube, aurora tube, electric egg, Gassiots cascade, air mill, bell in vacuum, density and buoyancy of air, fountain in vacuum, mercury shower, palm and bladder glasses, Bacchus demonstration, pneumatic man-lifter, and Magdeburg…

  10. Origin of reverse annealing effect in hydrogen-implanted silicon

    SciTech Connect

    Di, Zengfeng [Los Alamos National Laboratory; Nastasi, Michael A [Los Alamos National Laboratory; Wang, Yongqiang [Los Alamos National Laboratory

    2009-01-01

    In contradiction to conventional damage annealing, thermally annealed H-implanted Si exhibits an increase in damage or reverse annealing behavior, whose mechanism has remained elusive. On the basis of quantitative high resolution transmission electron microscopy combined with channeling Rutherford backscattering analysis, we conclusively elucidate that the reverse annealing effect is due to the nucleation and growth of hydrogen-induce platelets. Platelets are responsible for an increase in the height and width the channeling damage peak following increased isochronal anneals.

  11. Graphene tests of Klein phenomena

    E-print Network

    Stefano De Leo; Pietro Rotelli

    2012-02-07

    Graphene is characterized by chiral electronic excitations. As such it provides a perfect testing ground for the production of Klein pairs (electron/holes). If confirmed, the standard results for barrier phenomena must be reconsidered with, as a byproduct, the accumulation within the barrier of holes.

  12. Quantum Phenomena Observed Using Electrons

    SciTech Connect

    Tonomura, Akira [Okinawa Institute of Science and Technology, Onna-son, Okinawa 904-0412 (Japan); Advanced Research Laboratory, Hitachi, Ltd., Hatoyama, Saitama, 350-0395 (Japan); Advanced Science Institute, RIKEN, Wako, Saitama, 351-0198 (Japan)

    2011-05-06

    Electron phase microscopy based on the Aharonov-Bohm (AB) effect principle has been used to illuminate fundamental phenomena concerning magnetism and superconductivity by visualizing quantitative magnetic lines of force. This paper deals with confirmation experiments on the AB effect, the magnetization process of tiny magnetic heads for perpendicular recording, and vortex behaviors in high-Tc superconductors.

  13. Quantum imitations of physical phenomena.

    SciTech Connect

    Ortiz, G. (Gerardo)

    2001-01-01

    Quantum imitation is an attempt to exploit quantum laws to advantage, and thus accomplish efficient simulation of physical phenomena. We discuss the fundamental concepts behind this new paradigm of information processing, such as the connection between models of computation and physical systems, along with the first imitation of a toy quantum many-body problem.

  14. Wave phenomena in phononic crystals

    Microsoft Academic Search

    Alexey Sukhovich

    2007-01-01

    Novel wave phenomena in two- and three-dimensional (2D and 3D) phononic crystals were investigated experimentally using ultrasonic techniques. These ultrasonic techniques allow the full wave field to be imaged directly, which is a considerable advantage in fundamental studies of wave propagation in periodic media. Resonant tunnelling of ultrasonic waves was successfully observed for the first time by measuring the transmission

  15. Usefulness of Simulating Social Phenomena

    Microsoft Academic Search

    Pablo Lucas

    This paper discusses 1 the current usefulness and implications of developing research on agent-based Simulation Models of Social Phenomena (SMSP) beyond purely academic, hobbyist or educational purposes. Design, development and testing phases are discussed along with issues evidence-driven modellers often face whilst collecting, analysing and translating quantitative and qualitative empirical data into social simulation models. Methodological recommendations are discussed in

  16. Synthesis of large area, homogeneous, single layer graphene films by annealing amorphous carbon on Co and Ni

    Microsoft Academic Search

    Carlo M. Orofeo; Hiroki Ago; Baoshan Hu; Masaharu Tsuji

    2011-01-01

    The synthesis of large area, homogenous, single layer graphene on cobalt (Co) and nickel (Ni) is reported. The process involves\\u000a vacuum annealing of sputtered amorphous carbon (a-C) deposited on Co\\/sapphire or Ni\\/sapphire substrates. The improved crystallinity\\u000a of the metal film, assisted by the sapphire substrate, proves to be the key to the quality of as-grown graphene film. The\\u000a crystallinity of

  17. The dopant concentration and annealing temperature dependence of ferromagnetism in Co-doped ZnO thin films

    Microsoft Academic Search

    Xiao-Hong Xu; Xiu-Fang Qin; Feng-Xian Jiang; Xiao-Li Li; Ya Chen; G. A. Gehring

    2008-01-01

    A series of Zn1?xCoxO thin films with the atomic fraction, x, in the range of 0.03–0.10 were deposited on glass substrates at room temperature by magnetron co-sputtering technique and subsequently coupled with the post-annealing treatment for half hour at different temperatures (350°C and 500°C) under vacuum. A systematic study was done on the structural, optical and magnetic properties of Zn1?xCoxO

  18. The effects of composition and annealing conditions on the stability of columbium (niobium)-treated low-carbon steels

    Microsoft Academic Search

    R. E. Hook; J. A. Elias

    1972-01-01

    The effects of composition and annealing conditions on the yielding behavior of vacuum melted, columbium(niobium) -treated,\\u000a low-carbon steels were investigated. Additions of columbium were found to result in stabilization,i.e. freedom from inhomogeneous yielding or Lder’s strain in the as-recrystallized condition. Stabilization is accounted for\\u000a by considering the role of columbium as a carbide former, thereby reducing the carbon content in

  19. The effects of composition and annealing conditions on the stability of columbium (niobium)-treated low-carbon steels

    Microsoft Academic Search

    R. E. Hook; J. A. Elias

    1972-01-01

    The effects of composition and annealing conditions on the yielding behavior of vacuum melted, columbium(niobium) -treated, low-carbon steels were investigated. Additions of columbium were found to result in stabilization, i.e. freedom from inhomogeneous yielding or Lüder's strain in the as-recrystallized condition. Stabilization is accounted for by considering the role of columbium as a carbide former, thereby reducing the carbon content

  20. Ultrathin films of lead oxide on gold: Dependence of stoichiometry, stability and thickness on O 2 pressure and annealing temperature

    Microsoft Academic Search

    L. Bouzidi; A. J. Slavin

    2005-01-01

    Ultrathin oxide films grown in vacuum are important in many industrial areas, including microelectronics and heterogeneous catalysis. In this paper, the dependence of oxide stoichiometry, growth kinetics, thickness and stability on O2 pressure and annealing temperature are explored using a high-stability quartz-crystal microbalance and Auger spectroscopy, for the oxidation of lead on gold as a model system. The oxide thickness

  1. Flashover in vacuum tubes

    Microsoft Academic Search

    G. Damamme

    1998-01-01

    Despite a controversy that is as old as the model the secondary electron cascade for explaining the flashover still abounds. However, advanced understanding of charge trapping and associated energetic phenomena in insulators open new perspectives. The logic of pulse power experiments was to measure a flashover strength under short voltage pulses (ns, ?s). However, the dielectric strength is not a

  2. Tritium handling in vacuum systems

    SciTech Connect

    Gill, J.T. [Monsanto Research Corp., Miamisburg, OH (United States). Mound Facility; Coffin, D.O. [Los Alamos National Lab., NM (United States)

    1986-10-01

    This report provides a course in Tritium handling in vacuum systems. Topics presented are: Properties of Tritium; Tritium compatibility of materials; Tritium-compatible vacuum equipment; and Tritium waste treatment.

  3. Furnace brazing under partial vacuum

    NASA Technical Reports Server (NTRS)

    Mckown, R. D.

    1979-01-01

    Brazing furnace utilizing partial-vacuum technique reduces tooling requirements and produces better bond. Benefit in that partial vacuum helps to dissociate metal oxides that inhibit metal flow and eliminates heavy tooling required to hold parts together during brazing.

  4. Dendritic crystallization of amorphous germanium by in situ thermal pulse annealing

    NASA Astrophysics Data System (ADS)

    Lui, K. M.; Chik, K. P.; Xu, J. B.

    1997-06-01

    Phase transformation of amorphous-germanium thin film has been carried out on amorphous substrate by in situ thermal-pulse annealing in a high vacuum chamber directly after evaporation. The microstructure of the resultant film was shown to depend markedly both on the annealing ambient and on the time of exposure (te) for the as-deposited films under full-powered (<102W/cm2) incoherent broadband irradiation. The heating rate was estimated to be not less than 102K/s. The surface morphology of the sample was examined by atomic force microscopy (AFM), scanning electron microscopy, and optical microscopy. For samples annealed in air, hillock growth mode was observed, while for samples annealed in vacuum, a transition from the microgranular to dendritic grain growth, depending sensitively on te, was clearly evident. Surprisingly, the length of the crystallized dendrites could be as long as ?104?m, being at least ?104 times larger than the thickness of the film. The dendritic morphology, the implied growth rate, and the condition of crystallization lead us to suggest that the Ge film may exist in a supercooled semiconductive liquid phase just before crystallization. X-ray diffraction analysis revealed that grains were crystallized dominantly with a random orientation for te<2.84±0.05 s, while a sharp transition to a preferred <110> crystal orientation occurred at the critical te of 3.22±0.05 s, corresponding to a maximum temperature (Tm) of 577 °C reached by the system. This transition is consistent with the appearance of dendrites in AFM micrographs. More interestingly, an anomalous lateral size effect of the substrate on the misalignment of the <110> crystal direction of different grains with respect to the substrate normal was observed from the x-ray rocking curves. Careful inspection of the AFM images found that the giant dendrites broke up into individual columnar grains as the substrate width went down in size.

  5. Difficult to process? Vacuum it!

    SciTech Connect

    Eckles, A.J. [Atlanta Technology Group, GA (United States)

    1997-09-01

    Recent improvements in vacuum processing have broadened the technology`s use in the chemical process industries, running the gamut from vacuum distillation and evaporation, degassing, freeze drying, vapor deposition and etching, to vacuum filtrations. The paper discusses process improvements, attaining liquid distribution, medium-vacuum processing, falling-film evaporators, wiped-film evaporators, short-path evaporators, evaporation and crystallization, filtration, drying, refrigeration, freeze drying, degassing, semiconductor processing, pumps and their selection, and leak testing.

  6. A radiation hard vacuum switch

    DOEpatents

    Boettcher, G.E.

    1988-07-19

    A vacuum switch with an isolated trigger probe which is not directly connected to the switching electrodes. The vacuum switch within the plasmatron is triggered by plasma expansion initiated by the trigger probe which travels through an opening to reach the vacuum switch elements. The plasma arc created is directed by the opening to the space between the anode and cathode of the vacuum switch to cause conduction. 3 figs.

  7. Aging- and annealing-induced variations in Nb/Al-AlOx/Nb tunnel junction properties

    NASA Astrophysics Data System (ADS)

    Pavolotsky, Alexey B.; Dochev, Dimitar; Belitsky, Victor

    2011-01-01

    In this paper, we present studies of room temperature aging and annealing of Nb/Al-AlOx/Nb tunnel junctions with the size of 2-3 ?m2. We observed a noticeable drop of junction normal resistance Rn unusually combined with increase in subgap resistance Rj as a result of aging. Variation in both Rn and Rj are subject to the junction size effect. An effect of aging history on the junction degradation after consequent annealing was discovered. Discussion and interpretation of the observed phenomena are presented in terms of structural ordering and reconstruction in the AlOx layer, driven by diffusion flows enhanced due to stress relaxation processes in the Al layer interfacing the AlOx layer.

  8. Vacuum Energy: Myths and Reality

    E-print Network

    G. E. Volovik

    2006-07-10

    We discuss the main myths related to the vacuum energy and cosmological constant, such as: ``unbearable lightness of space-time''; the dominating contribution of zero point energy of quantum fields to the vacuum energy; non-zero vacuum energy of the false vacuum; dependence of the vacuum energy on the overall shift of energy; the absolute value of energy only has significance for gravity; the vacuum energy depends on the vacuum content; cosmological constant changes after the phase transition; zero-point energy of the vacuum between the plates in Casimir effect must gravitate, that is why the zero-point energy in the vacuum outside the plates must also gravitate; etc. All these and some other conjectures appear to be wrong when one considers the thermodynamics of the ground state of the quantum many-body system, which mimics macroscopic thermodynamics of quantum vacuum. In particular, in spite of the ultraviolet divergence of the zero-point energy, the natural value of the vacuum energy is comparable with the observed dark energy. That is why the vacuum energy is the plausible candidate for the dark energy.

  9. Crystallization phenomena in thin films of amorphous barium hexaferrite

    NASA Astrophysics Data System (ADS)

    Gerard, P.; Lacroix, E.; Marest, G.; Blanchard, B.; Rolland, G.; Rolland, B.; Bechevet, B.

    1989-07-01

    It is an investigation on crystallization phenomena by post-deposition annealings of amorphous thin films of M type barium hexaferrite made either at room temperature (A samples) or at 400°C (B samples). Both amorphous layers were deposited by facing target sputtering system. The evolution of magnetic and crystalline properties of A and B samples were studied as a function of isochronous thermal treatments under air or oxygen. After different annealing steps, samples were characterized for the structure and the composition by X-ray and by secondary ion mass spectrometry respectively and for the magnetic properties by a vibrating sample magnetometer and by conversion electron Mössbauer spectroscopy. Stress measurements were also performed using a Fizeau interferometer. On the whole, it turns out that B samples are well textured, the c-axis being rather well perpendicular to the surface of the substance. This gives rise to the desired perpendicular anisotropy. As for A samples, they display isomorphous magnetic behaviour having no preferential crystalline orientation. Huge hydroxyl group absorption found in A with respect to B samples seems to be at the origin of discrepancies between the two amorphous hexaferrites made at different temperatures.

  10. Thermal annealing of radiation damaged titanite

    SciTech Connect

    Chrosch, J.; Colombo, M.; Malcherek, T.; Salje, E.K.H. [Univ. of Cambridge (United Kingdom). Dept. of Earth Sciences; Groat, L.A. [Univ. of British Columbia, Vancouver (Canada). Dept. of Earth and Ocean Sciences; Bismayer, U. [Univ. Hamburg (Germany). Mineralogisch-Petrographisches Inst.

    1998-09-01

    Radiogenic impurities of 400 to 800 ppm U and Th in titanite, CaTiSiO{sub 5}, lead to moderate radiation damage ({approx}1.5 {times} 10{sup 18} {alpha}-decay events/g) and therefore to partial amorphization ({approx}30%). Powder X-ray diffraction on such damaged titanite from the Cardiff locality in Canada shows that two modifications of the crystalline material coexist. Both modifications are structurally {beta} phase but differ systematically in their lattice parameters and also in their chemical composition. One modification exhibits strong particle size broadening in X-ray diffraction patterns, whereas it is almost unstrained with respect to fully annealed titanite. The other modification shows large strain broadening and increased specific volume (about 3%) due to a high concentration of defects. The unstrained modification consists of small nucleation centers in the damaged material, and it grows when the sample is annealed. At annealing temperatures above 823 K, this modification dominates rapidly and replaces the strained titanite. The results of Rietveld refinement of the annealed samples and of the time evolution of isothermal annealing studies are discussed. The analysis of volume strain and of structural strain resulting from the peak profiles suggests a temperature-dependent activation energy for the recrystallization process, with E{sub A} {approx} 380 kJ/mol at T > 873 K and E{sub A} {approx} 500 kJ/mol at temperatures 773 K < T < 873 K.

  11. Annealing Effect on Exchange Bias in NiFe\\/FeMn\\/CoFe Trilayer Thin Films

    Microsoft Academic Search

    Ki-Yeon Kim; Hyeok-Cheol Choi; Chun-Yeol You; Jeong-Soo Lee

    We investigated the exchange bias fields at the NiFe\\/FeMn and FeMn\\/CoFe interfaces in 18.9-nm NiFe\\/15.0-nm FeMn\\/17.6-nm CoFe trilayer thin films as the annealing temperature was varied from room temperature to 250oC in a vacuum for 1 hour in a magnetic field of 150 Oe. Interestingly, magnetic hysteresis (M-H) measure- ments showed that NiFe\\/FeMn\\/CoFe trilayer thin films exhibited a completely contrasting

  12. Compact vacuum insulation embodiments

    DOEpatents

    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.

  13. Vacuum tool manipulator

    DOEpatents

    Zollinger, W.T.

    1993-11-23

    Apparatus for manipulating a vacuum hose in a reactor vessel comprises a housing with two opposing openings, an arm carried by the housing and deployable from a stowed position essentially completely within the housing to an extended position where the arm extends through the two openings in a generally horizontal position. The arm preferably has a two-fingered gripping device for gripping the vacuum hose but may carry a different end effector such as a grinding wheel. The fingers are opened and closed by one air cylinder. A second air cylinder extends the device. A third air cylinder within the housing pivotally pulls the opposing end of the arm into the housing via a pivoting member pivotally connected between the third air cylinder shaft and the arm. 6 figures.

  14. Vacuum tool manipulator

    DOEpatents

    Zollinger, William T. (3927 Almon Dr., Martinez, GA 30907)

    1993-01-01

    Apparatus for manipulating a vacuum hose in a reactor vessel comprises a housing with two opposing openings, an arm carried by the housing and deployable from a stowed position essentially completely within the housing to an extended position where the arm extends through the two openings in a generally horizontal position. The arm preferably has a two-fingered gripping device for gripping the vacuum hose but may carry a different end effector such as a grinding wheel. The fingers are opened and closed by one air cylinder. A second air cylinder extends the device. A third air cylinder within the housing pivotally pulls the opposing end of the arm into the housing via a pivoting member pivotally connected between the third air cylinder shaft and the arm.

  15. Compact vacuum insulation

    DOEpatents

    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.

  16. Effects of annealing in Be/W and Be/C bilayers deposited on Si(0 0 1) substrates with Fe buffer layers

    NASA Astrophysics Data System (ADS)

    Schinteie, G.; Greculeasa, S. G.; Palade, P.; Lungu, G. A.; Porosnicu, C.; Jepu, I.; Lungu, C. P.; Filoti, G.; Kuncser, V.

    2015-02-01

    Atomic intermixing processes in relation to structural aspects and phase formation in Be based thin films subjected to different annealing treatments simulating the case of re-deposited layered structures on plasma facing components in nuclear fusion devices are reported. Accordingly, bilayers of Be/W and Be/C have been deposited on Si(0 0 1) substrates with Fe buffer layers. The Fe films have been prepared by radiofrequency sputtering and further processed by annealing in hydrogen atmosphere at 300 °C, for 90 min, at a pressure of 10 bars of H2. After the Be/W and Be/C bilayer deposition by means of thermionic vacuum arc method, annealing in vacuum at 600 °C, for 10 min has been applied to the complex structures. The influence of annealing on the phase composition and atomic intermixing processes in the complex structures has been studied by means of X-ray photoelectron spectroscopy (XPS) and conversion electron Mössbauer spectroscopy (CEMS). The layered structures present an oxidation gradient with oxide phases in the uppermost layers and non-oxidized phases in the lower layers, as observed from the XPS data. The CEMS results revealed that the as-deposited structures contain a main metallic Fe phase and secondary superparamagnetic Fe oxide phases at the Fe/Be interface, while annealed samples present a large contribution of Fe-Be and Fe-C mixtures. The annealing treatment induces considerable atomic interdiffusion, strongly dependent on the nature of the upper layer. In the case of Be/W system, the annealing provides a much rougher Be/W interface, while in case of the Be/C structure, the annealing treatment only homogenize the structure over the whole depth.

  17. Decoherence and Vacuum Fluctuations

    Microsoft Academic Search

    L. H. Ford

    1994-01-01

    The interference pattern of coherent electrons is effected by coupling to the\\u000aquantized electromagnetic field. The amplitudes of the interference maxima are\\u000achanged by a factor which depends upon a double line integral of the photon\\u000atwo-point function around the closed path of the electrons. The interference\\u000apattern is sensitive to shifts in the vacuum fluctuations in regions from which

  18. Decoherence and Vacuum Fluctuations

    E-print Network

    L. H. Ford

    1994-08-30

    The interference pattern of coherent electrons is effected by coupling to the quantized electromagnetic field. The amplitudes of the interference maxima are changed by a factor which depends upon a double line integral of the photon two-point function around the closed path of the electrons. The interference pattern is sensitive to shifts in the vacuum fluctuations in regions from which the electrons are excluded. Thus this effect combines aspects of both the Casimir and the Aharonov-Bohm effects. The coupling to the quantized electromagnetic field tends to decrease the amplitude of the interference oscillations, and hence is a form of decoherence. The contributions due to photon emission and to vacuum fluctuations may be separately identified. It is to be expected that photon emission leads to decoherence, as it can reveal which path an electron takes. It is less obvious that vacuum fluctuations also can cause decoherence. What is directly observable is a shift in the fluctuations due, for example, to the presence of a conducting plate. In the case of electrons moving parallel to conducting boundaries, the dominant decohering influence is that of the vacuum fluctuations. The shift in the interference amplitudes can be of the order of a few percent, so experimental verification of this effect may be possible. The possibility of using this effect to probe the interior of matter, e.g., to determine the electrical conductivity of a rod by means of electrons encircling it is discussed. (Presented at the Conference on Fundamental Problems in Quantum Theory, University of Maryland, Baltimore County, June 18-22, 1994.)

  19. Vacuum Ultraviolet Detector

    NASA Astrophysics Data System (ADS)

    Shao, Chun-Lin; Tomita, Kazuhiro; Jimbo, Takashi; Umeno, Masayoshi; Hattori, Shuzo

    1985-02-01

    A new vacuum ultraviolet detector has been fabricated. A sample was made using a crystalline quartz plate on the surface of which a metal electrode was deposited. It has been experimentally established that the sample is sensitive to VUV radiation, and the external quantum efficiency is estimated to be higher than several percent. The new photodetector also has very good stability and should be a practicable new VUV photodetector.

  20. Decoherence and vacuum fluctuations

    E-print Network

    Ford, L H

    1994-01-01

    The interference pattern of coherent electrons is effected by coupling to the quantized electromagnetic field. The amplitudes of the interference maxima are changed by a factor which depends upon a double line integral of the photon two-point function around the closed path of the electrons. The interference pattern is sensitive to shifts in the vacuum fluctuations in regions from which the electrons are excluded. Thus this effect combines aspects of both the Casimir and the Aharonov-Bohm effects. The coupling to the quantized electromagnetic field tends to decrease the amplitude of the interference oscillations, and hence is a form of decoherence. The contributions due to photon emission and to vacuum fluctuations may be separately identified. It is to be expected that photon emission leads to decoherence, as it can reveal which path an electron takes. It is less obvious that vacuum fluctuations also can cause decoherence. What is directly observable is a shift in the fluctuations due, for example, to the pr...

  1. Emergent Phenomena via Molecular Dynamics

    NASA Astrophysics Data System (ADS)

    Rapaport, D. C.

    Emergent phenomena are unusual because they are not obvious consequences of the design of the systems in which they appear, a feature no less relevant when they are being simulated. Several systems that exhibit surprisingly rich emergent behavior, each studied by molecular dynamics (MD) simulation, are described: (i) Modeling self-assembly processes associated with virus growth reveals the ability to achieve error-free assembly, where paradoxically, near-maximum yields are due to reversible bond formation. (ii) In fluids studied at the atomistic level, complex hydrodynamic phenomena in rotating and convecting fluids - the Taylor- Couette and Rayleigh-Bénard instabilities - can be reproduced, despite the limited length and time scales accessible by MD. (iii) Segregation studies of granular mixtures in a rotating drum reproduce the expected, but counterintuitive, axial and radial segregation, while for the case of a vertically vibrated layer a novel form of horizontal segregation is revealed.

  2. Undergraduates Understanding of Cardiovascular Phenomena

    NSDL National Science Digital Library

    PhD Joel A. Michael (Rush Medical College Department of Molecular Biophysics and Physiology)

    2002-06-01

    Undergraduates students in 12 courses at 8 different institutions were surveyed to determine the prevalence of 13 different misconceptions (conceptual difficulties) about cardiovascular function. The prevalence of these misconceptions ranged from 20 to 81% and, for each misconception, was consistent across the different student populations. We also obtained explanations for the studentsÂ? answers either as free responses or with follow-up multiple-choice questions. These results suggest that students have a number of underlying conceptual difficulties about cardiovascular phenomena. One possible source of some misconceptions is the studentsÂ? inability to apply simple general models to specific cardiovascular phenomena. Some implications of these results for teachers of physiology are discussed.

  3. Statistical phenomena in particle beams

    SciTech Connect

    Bisognano, J.J.

    1984-09-01

    Particle beams are subject to a variety of apparently distinct statistical phenomena such as intrabeam scattering, stochastic cooling, electron cooling, coherent instabilities, and radiofrequency noise diffusion. In fact, both the physics and mathematical description of these mechanisms are quite similar, with the notion of correlation as a powerful unifying principle. In this presentation we will attempt to provide both a physical and a mathematical basis for understanding the wide range of statistical phenomena that have been discussed. In the course of this study the tools of the trade will be introduced, e.g., the Vlasov and Fokker-Planck equations, noise theory, correlation functions, and beam transfer functions. Although a major concern will be to provide equations for analyzing machine design, the primary goal is to introduce a basic set of physical concepts having a very broad range of applicability.

  4. Hydrogen Annealing Of Single-Crystal Superalloys

    NASA Technical Reports Server (NTRS)

    Smialek, James L.; Schaeffer, John C.; Murphy, Wendy

    1995-01-01

    Annealing at temperature equal to or greater than 2,200 degrees F in atmosphere of hydrogen found to increase ability of single-crystal superalloys to resist oxidation when subsequently exposed to oxidizing atmospheres at temperatures almost as high. Supperalloys in question are principal constituents of hot-stage airfoils (blades) in aircraft and ground-based turbine engines; also used in other high-temperature applications like chemical-processing plants, coal-gasification plants, petrochemical refineries, and boilers. Hydrogen anneal provides resistance to oxidation without decreasing fatigue strength and without need for coating or reactive sulfur-gettering constituents. In comparison with coating, hydrogen annealing costs less. Benefits extend to stainless steels, nickel/chromium, and nickel-base alloys, subject to same scale-adhesion and oxidation-resistance considerations, except that scale is chromia instead of alumina.

  5. New phenomena searches at CDF

    SciTech Connect

    Soha, Aron; /UC, Davis

    2006-04-01

    The authors report on recent results from the Collider Detector at Fermilab (CDF) experiment, which is accumulating data from proton-antiproton collisions with {radical}s = 1.96 TeV at Run II of the Fermilab Tevatron. The new phenomena being explored include Higgs, Supersymmetry, and large extra dimensions. They also present the latest results of searches for heavy objects, which would indicate physics beyond the Standard Model.

  6. Neural Correlates of Insight Phenomena

    Microsoft Academic Search

    Jing Luo; Gunther Knoblich; Chongde Lin

    2009-01-01

    Difficult problems are sometimes solved in a sudden flash of illumination, a phenomenon referred to as “insight.” Recent neuroimaging\\u000a studies have begun to reveal the neural correlates of the cognitive processes underlying such insight phenomena (Luo and Niki\\u000a 2003; Jung-Beeman et al. 2004; Luo et al. 2004a, 2006; Mai et al. 2004; Lang et al. 2006). However, researchers have encountered

  7. REVIEW ARTICLE: Valence fluctuation phenomena

    Microsoft Academic Search

    J. M. Lawrence; P. S. Riseborough; R. D. Parks

    1981-01-01

    Valence fluctuation phenomena occur in rare-earth compounds in which the proximity of the 4f level to the Fermi energy leads to instabilities of the charge configuration (valence) and\\/or of the magnetic moment. The authors review the experimental results observed in the subset of such systems for which the 4f ions form a lattice with identical valence on each site. The

  8. Insulation Phenomena of Compressed Air

    Microsoft Academic Search

    L. D. McConnell

    1957-01-01

    Test data on impulse and 60-cycle voltage breakdown strength for compressed air with various electrode configurations are reported. The tests were made with rod-to-plane electrodes with spacings up to 8 inches and pressures to 250 psig (pounds per square inch gage). Breakdown phenomena of air insulation encountered in the development of an air insulated air-blast circuit breaker1 are reported. The

  9. THE EFFECT OF POST-IRRADATION ANNEALING ON STACKING FAULT TETRAHEDRA IN NEUTRON-IRRADIATED OFHC COPPER

    SciTech Connect

    Edwards, Danny J.; Singh, Bachu N.; Eldrup, M.

    2003-09-03

    Two irradiation experiments have been completed wherein two sets of tensile specimens of OFHC copper were irradiated with fission neutrons, one set at 200 degrees C and the other at 250 degrees C. Post-irradiation annealing in vacuum was then used to evaluate the change in the defect microstructure, including vacancy-type SFT, voids, and dislocation loops. Individual samples within each set were given one annealing exposure at 300, 350, 400, 450, 500, or 550 degrees C for 2 hours. The fine-scale defect microstructure was characterized by transmission electron microscopy (TEM) to compare the defect size and spatial distribution at each annealing temperature and reference the results to that measured in the as-irradiated condition. Based on the change in the SFT size distributions, post-irradiation annealing led to a preferential removal of the smaller sized SFT, but did not lead to a general coarsening as might be expected from an Oswald ripening scenario. The issue of whether the SFT produced during irradiation are all structurally perfect is still being investigated at the time of this report, however, the images of the SFT appeared more perfect after annealing at 300 degrees C and higher. Further analysis is being performed to determine whether intermediate stages of SFT formation exist in the as-irradiated condition.

  10. Work Hardening and Annealing of Copper

    NSDL National Science Digital Library

    Stoebe, Thomas G.

    This activity will demonstrate the process of work hardening and annealing of a copper. Students will get the opportunity to see the hardening of metal by deformation, experience the process of work hardening, explain the effects of work hardening in metals and experience property changes affected by annealing. This activity would be appropriate for grades 4 through high school and college level, with each age group gaining different educational benefits. Around 60 minutes is required for the demonstration. Student, instructor and course evaluation questions are included. This document will serve as a framework for instructors and may be downloaded in PDF format.

  11. Rock melting tool with annealer section

    SciTech Connect

    Bussod, Gilles Y. (Santa Fe, NM); Dick, Aaron J. (Oakland, CA); Cort, George E. (Montrose, CO)

    1998-01-01

    A rock melting penetrator is provided with an afterbody that rapidly cools a molten geological structure formed around the melting tip of the penetrator to the glass transition temperature for the surrounding molten glass-like material. An annealing afterbody then cools the glass slowly from the glass transition temperature through the annealing temperature range to form a solid self-supporting glass casing. This allows thermally induced strains to relax by viscous deformations as the molten glass cools and prevents fracturing of the resulting glass liner. The quality of the glass lining is improved, along with its ability to provide a rigid impermeable casing in unstable rock formations.

  12. Quantum Annealing in a Kinetically Constrained System

    E-print Network

    Arnab Das; Bikas K. Chakrabarti; Robin B. Stinhcombe

    2005-02-07

    Classical and quantum annealing is discussed for a kinetically constrained chain of $N$ non-interacting asymmetric double wells, represented by Ising spins in a longitudinal field $h$. It is shown that in certain cases, where the kinetic constraints may arise from infinitely high but vanishingly narrow barriers appearing in the relaxation path of the system, quantum annealing exploiting the quantum-mechanical penetration of sufficiently narrow barriers may be far more efficient than its thermal counterpart. We have used a semiclassical picture of scattering dynamics to do our simulation for the quantum system.

  13. Quantum Annealing and Analog Quantum Computation

    E-print Network

    Arnab Das; Bikas K. Chakrabarti

    2008-03-24

    We review here the recent success in quantum annealing, i.e., optimization of the cost or energy functions of complex systems utilizing quantum fluctuations. The concept is introduced in successive steps through the studies of mapping of such computationally hard problems to the classical spin glass problems. The quantum spin glass problems arise with the introduction of quantum fluctuations, and the annealing behavior of the systems as these fluctuations are reduced slowly to zero. This provides a general framework for realizing analog quantum computation.

  14. Improved zircon fission-track annealing model based on reevaluation of annealing data

    SciTech Connect

    Guedes, Sandro [Instituto de Fisica Gleb Wataghin, Unicamp, Brazil; Moreira, Pedro A.F.P. [Universidade Estadual de Campinas, Sao Paulo; Devanathan, Ram [Pacific Northwest National Laboratory (PNNL); Weber, William J [ORNL; Hadler, Julio C [Instituto de Fisica Gleb Wataghin, Unicamp, Brazil

    2013-01-01

    The thermal recovery (annealing) of mineral structure modified by the passage of fission fragments has long been studied by the etching technique. In minerals like apatite and zircon, the annealing kinetics are fairly well constrained from the hour to the million-year timescale and have been described by empirical and semi-empirical equations. On the other hand, laboratory experiments, in which ion beams interact with minerals and synthetic ceramics, have shown that there is a threshold temperature beyond which thermal recovery impedes ion-induced amorphization. In this work, it is assumed that this behavior can be extended to the annealing of fission tracks in minerals. It is proposed that there is a threshold temperature, T0, beyond which fission tracks are erased within a time t0, which is independent of the current state of lattice deformation. This implies that iso-annealing curves should converge to a fanning point in the Arrhenius pseudo-space (ln t vs. 1/T). Based on the proposed hypothesis, and laboratory and geological data, annealing equations are reevaluated. The geological timescale estimations of a model arising from this study are discussed through the calculation of partial annealing zone and closure temperature, and comparison with geological sample constraints found in literature. It is shown that the predictions given by this model are closer to field data on closure temperature and partial annealing zone than predictions given by previous models.

  15. Improved zircon fission-track annealing model based on reevaluation of annealing data

    SciTech Connect

    Guedes, S.; Moreira, Pedro; Devanathan, Ramaswami; Weber, William J.; Hadler, J. C.

    2012-11-10

    The thermal recovery (annealing) of mineral structure modified by the passage of fission fragments has long been studied by the etching technique. In minerals like apatite and zircon, the annealing kinetics are fairly well constrained from the hour to the million-year timescale and have been described by empirical and semi-empirical equations. On the other hand, laboratory experiments, in which ion beams interact with minerals and synthetic ceramics, have shown that there is a threshold temperature beyond which thermal recovery impedes ion-induced amorphization. In this work, it is assumed that this behavior can be extended to the annealing of fission tracks in minerals. It is proposed that there is a threshold temperature, T 0, beyond which fission tracks are erased within a time t 0, which is independent of the current state of lattice deformation. This implies that iso-annealing curves should converge to a fanning point in the Arrhenius pseudo-space (ln t vs. 1/T). Based on the proposed hypothesis, and laboratory and geological data, annealing equations are reevaluated. The geological timescale estimations of a model arising from this study are discussed through the calculation of partial annealing zone and closure temperature, and comparison with geological sample constraints found in literature. It is shown that the predictions given by this model are closer to field data on closure temperature and partial annealing zone than predictions given by previous models.

  16. The microstructural response of mill-annealed and solution-annealed INCONEL 600 to heat treatment

    NASA Astrophysics Data System (ADS)

    Hall, Ernest L.; Briant, Clyde L.

    1985-07-01

    Samples of INCONEL* 600 were examined in the mill-annealed and solution-annealed states, and after isothermal annealing at 400 °C and 650 °C. The corrosion behavior of the samples was examined, analytical electron microscopy was used to determine the microstructures present and the chemistry of grain boundaries, and Auger electron spectroscopy was used to measure grain boundary segregation. Samples of different alloys in the mill-annealed state were found to have quite different microstructures, with Cr-rich M7C3 carbides occurring either along grain boundaries or in intragranular sheets. The corrosion behavior of the samples correlated well with the occurrence of grain boundary chromium depletion. Solution annealing at 1190 °C caused dissolution of all carbides, whereas at 1100 °C the carbides either dissolved or the grain boundaries moved away from the carbides, depending upon alloy carbon content. Low-temperature annealing at 400 °C had little effect on millannealed or fully solutionized samples, but in samples with intragranular carbides present, the grain boundaries moved until intersecting or adjacent to the carbides. Isothermal annealing at 650 °C caused carbide nucleation and growth at grain boundaries in fully solutionized samples. Chromium depletion at grain boundaries accompanied carbide precipitation, with a minimum chromium level of 6 wt pct achieved after 5 hours. Healing was found to occur after 100 hours. Solution-annealed samples with intragranular carbides present had more rapid corrosion kinetics since the grain boundaries moved back to the existing carbides. Thermodynamic analysis of the chromium-depletion process showed good agreement with experimental measurements. The Auger results found only boron present at grain boundaries in the mill-annealed state. Aged samples had boron, nitrogen, and phosphorus present, with phosphorus and nitrogen segregating to the greatest extent. The kinetics of phosphorus segregation are much slower at 400 °C compared with 650 °C.

  17. Vacuum ultraviolet and infrared spectra of condensed methyl acetate on cold astrochemical dust analogs

    SciTech Connect

    Sivaraman, B. [Space and Atmospheric Sciences Division, Physical Research Laboratory, Ahmedabad 380009 (India); Nair, B. G.; Mason, N. J. [Department of Physical Sciences, The Open University, Walton Hall, Milton Keynes MK7 6AA (United Kingdom); Lo, J.-I.; Cheng, B.-M. [National Synchrotron Radiation Research Center, 101 Hsin-Ann Road, Hsinchu Science Park, Hsinchu 30076, Taiwan (China); Kundu, S.; Davis, D.; Prabhudesai, V.; Krishnakumar, E. [Department of Nuclear and Atomic Physics, Tata Institute of Fundamental Research, Mumbai 400005 (India); Raja Sekhar, B. N., E-mail: bhala@prl.res.in [B-4, Indus-1, BARC Spectroscopy Lab at Indus-1, Atomic and Molecular Physics Division, BARC, Mumbai and RRCAT, Indore 452013 (India)

    2013-12-01

    Following the recent report of the first identification of methyl acetate (CH{sub 3}COOCH{sub 3}) in the interstellar medium (ISM), we have carried out vacuum ultraviolet (VUV) and infrared (IR) spectroscopy studies on methyl acetate from 10 K until sublimation in an ultrahigh vacuum chamber simulating astrochemical conditions. We present the first VUV and IR spectra of methyl acetate relevant to ISM conditions. Spectral signatures clearly showed molecular reorientation to have started in the ice by annealing the amorphous ice formed at 10 K. An irreversible phase change from amorphous to crystalline methyl acetate ice was found to occur between 110 K and 120 K.

  18. Vacuum Ultraviolet and Infrared Spectra of Condensed Methyl Acetate on Cold Astrochemical Dust Analogs

    NASA Astrophysics Data System (ADS)

    Sivaraman, B.; Nair, B. G.; Lo, J.-I.; Kundu, S.; Davis, D.; Prabhudesai, V.; Raja Sekhar, B. N.; Mason, N. J.; Cheng, B.-M.; Krishnakumar, E.

    2013-12-01

    Following the recent report of the first identification of methyl acetate (CH3COOCH3) in the interstellar medium (ISM), we have carried out vacuum ultraviolet (VUV) and infrared (IR) spectroscopy studies on methyl acetate from 10 K until sublimation in an ultrahigh vacuum chamber simulating astrochemical conditions. We present the first VUV and IR spectra of methyl acetate relevant to ISM conditions. Spectral signatures clearly showed molecular reorientation to have started in the ice by annealing the amorphous ice formed at 10 K. An irreversible phase change from amorphous to crystalline methyl acetate ice was found to occur between 110 K and 120 K.

  19. A study of surface features resulting from oxidation and thermal etching of a single crystal of lithium hydride during a 350°C high vacuum bake

    NASA Astrophysics Data System (ADS)

    Simandl, R. F.; McLaughlin, J. F.

    1981-10-01

    Thermal etching of single crystals of lithium hydride annealed at 350° C under 30 ?Pa vacuum in the presence of a polycrystalline LiH getter contributes to the formation of an unusual rectangular maze surface morphology. This morphology was extensively developed on crystal faces that were not in contact with the stainless containers during the anneal. For faces in contact with the steel container, maze formation was apparently limited by the conductance of free lithium away from the LiH surface. Despite attempts to eliminate residual oxygen and water from the high vacuum system, the LiH samples nevertheless became oxidized to a limited extent.

  20. Transient phenomena on ZT-40

    SciTech Connect

    Jacobson, A.R.; Buchenauer, C.J.

    1980-01-01

    Two aspects of fluctuations in the ZT-40 reversed-field pinch are examined. First, the polarization of the magnetic fluctuations in the outer (vacuum) region is discussed. This in turn provides information on the wavevectors associated with the turbulence. The results provide some clues about the location (in minor radius) of the singular surfaces which are customarily associated with fluctuations. Second, the density fluctuations are studied using a multichord interferometer. The spatial distribution (in major radius) of the chord-averaged fluctuations are also described.

  1. What is vacuum?

    E-print Network

    Rowlands, Peter

    2008-01-01

    Vacuum can be defined with exact mathematical precision as the state which remains when a fermion, with all its special characteristics, is created out of absolutely nothing. The definition leads to a special form of relativistic quantum mechanics, which only requires the construction of a creation operator. This form of quantum mechanics is especially powerful for analytic calculation, at the same time as explaining, from first principles, many aspects of the Standard Model of particle physics. In particular, the characteristics of the weak, strong and electric interactions can be derived from the structure of the creation operator itself.

  2. What is vacuum?

    E-print Network

    Peter Rowlands

    2008-10-01

    Vacuum can be defined with exact mathematical precision as the state which remains when a fermion, with all its special characteristics, is created out of absolutely nothing. The definition leads to a special form of relativistic quantum mechanics, which only requires the construction of a creation operator. This form of quantum mechanics is especially powerful for analytic calculation, at the same time as explaining, from first principles, many aspects of the Standard Model of particle physics. In particular, the characteristics of the weak, strong and electric interactions can be derived from the structure of the creation operator itself.

  3. Avoiding Death by Vacuum

    E-print Network

    A. Barroso; P. M. Ferreira; I. Ivanov; R. Santos; Joao P. Silva

    2013-05-08

    The two-Higgs doublet model (2HDM) can have two electroweak breaking, CP-conserving, minima. The possibility arises that the minimum which corresponds to the known elementary particle spectrum is metastable, a possibility we call the "panic vacuum". We present analytical bounds on the parameters of the softly broken Peccei-Quinn 2HDM which are necessary and sufficient conditions to avoid this possibility. We also show that, for this particular model, the current LHC data already tell us that we are necessarily in the global minimum of the theory, regardless of any cosmological considerations about the lifetime of the false vacua.

  4. Polymers in a Vacuum

    SciTech Connect

    Deutsch, J. M. [Department of Physics, University of California, Santa Cruz, California 95064 (United States)

    2007-12-07

    In a variety of situations, isolated polymer molecules are found in a vacuum, and here we examine their properties. Angular momentum conservation is shown to significantly alter the average size of a chain and its conservation is only broken slowly by thermal radiation. For an ideal chain, the time autocorrelation for monomer position oscillates with a period proportional to chain length. The oscillations and damping are analyzed in detail. Short-range repulsive interactions suppress oscillations and speed up relaxation, but stretched chains still show damped oscillatory correlations.

  5. Macroscopic, freestanding, and tubular graphene architectures fabricated via thermal annealing.

    PubMed

    Nguyen, Duc Dung; Suzuki, Seiya; Kato, Shuji; To, Bao Dong; Hsu, Chia Chen; Murata, Hidekazu; Rokuta, Eiji; Tai, Nyan-Hwa; Yoshimura, Masamichi

    2015-03-24

    Manipulation of individual graphene sheets/films into specific architectures at macroscopic scales is crucially important for practical uses of graphene. We present herein a versatile and robust method based on annealing of solid carbon precursors on nickel templates and thermo-assisted removal of poly(methyl methacrylate) under low vacuum of ?0.6 Pa for fabrication of macroscopic, freestanding, and tubular graphene (TG) architectures. Specifically, the TG architectures can be obtained as individual and woven tubes with a diameter of ?50 ?m, a wall thickness in the range of 2.1-2.9 nm, a density of ?1.53 mg·cm(-3), a thermal stability up to 600 °C in air, an electrical conductivity of ?1.48 × 10(6) S·m(-1), and field emission current densities on the order of 10(4) A·cm(-2) at low applied electrical fields of 0.6-0.7 V·?m(-1). These properties show great promise for applications in flexible and lightweight electronics, electron guns, or X-ray tube sources. PMID:25738973

  6. Ridge formation and removal via annealing in exfoliated graphene.

    PubMed

    Han, Sang A; Choi, In Sung; An, Hyo Sub; Lee, Hyunsoo; Yong, Hyeon Deuk; Lee, Sangwook; Jung, Jongwan; Lee, Nae Sung; Seo, Yongho

    2011-07-01

    It is well known that graphene is a very promising material due to its excellent physical, chemical, and thermal properties. Previously, ridges in graphene on a substrate were found in epitaxial graphene on a SiC substrate. It was found in this study that ridges can be made on a graphene layer via mechanical exfoliation on a sapphire substrate, and that ridges can be created or removed through heating and cooling. Due to the difference of the thermal-expansion coefficients of the substrate and graphene, it can be said that thermal cycling causes compressive strain, which is released by forming ridges. Annealing was carried out in a vacuum chamber within the pressure range of 10(-3)-10(-6) Torr and at 900-1100 degrees C. To analyze the shapes and mechanical properties of the ridges, Raman spectroscopy and AFM measurement were performed. It was found that the ridges can be extended by defect as a nucleation center, and the graphene layer can be folded along the preexisting ridge during heating and cooling. PMID:22121637

  7. Fourier Analysis of Fast Vacuum Arc Parameters

    SciTech Connect

    Anders, Andre; Oks, Efim M.; Yushkov, Georgy Yu.

    2006-08-17

    Vacuum arcs are known for their noisy character: allparameters show more-or-less rapid fluctuations. This is of particularconcern to those who would like to utilize the exceptional properties ofthe vacuum arc plasma in ion sources and other devices. Among theseproperties are the very high degree of ionization and the presence ofmultiply ionized species. The rapid fluctuations are known to beultimately caused by the explosive nature of the perpetual spot ignitionand plasma production. We present a systematic application of the FastFourier Transform to the fluctuating arc voltage and current. Newpossibilities have arisen with the advent of fast digital oscilloscopesand low cost computation of large amounts of data. We show that thespectral power density (SPD) scales with a power law in log-logpresentation for all frequencies below 50 MHz, supporting a fractaldescription of the cathode spot phenomena below this limit. At higherfrequencies, the result is less clear. The fractal behavior seems to becut off as indicated by material dependent fluctuations which are abovethe level found for the power law at lower frequencies. This might beassociated with approaching the region of individual explosive processes,also known as ectons. However, the nonlinear behavior of the SPD containspeaks that are the same for different materials, indicating thatresonances in the measuring circuit play a role, too. Hence, fractalbehavior may be possible for frequencies faster than 50 MHz.

  8. Positron prevacancy effects in pure annealed metals

    SciTech Connect

    Smedskjaer, L.C.

    1981-06-01

    The low-temperature prevacancy effects sometimes observed with positrons in well-annealed high-purity metals are discussed. It is shown that these effects are not experimental artifacts, but are due to trapping of the positrons. It is suggested that dislocations are responsible for these trapping effects. 46 references, 5 figures.

  9. Drawing graphs nicely using simulated annealing

    Microsoft Academic Search

    Ron Davidson; David Harel

    1996-01-01

    The paradigm of simulated annealing is applied to the problem of drawing graphs “nicely.” Our algorithm deals with general undirected graphs with straight-line edges, and employs several simple criteria for the aesthetic quality of the result. The algorithm is flexible, in that the relative weights of the criteria can be changed. For graphs of modest size it produces good results,

  10. Simulated annealing, acceleration techniques, and image restoration

    Microsoft Academic Search

    Marc C. Robini; Thierry Rastello; Isabelle E. Magnin

    1999-01-01

    Typically, the linear image restoration problem is an ill-conditioned, underdetermined inverse problem. Here, stabilization is achieved via the introduction of a first-order smoothness constraint which allows the preservation of edges and leads to the minimization of a nonconvex functional. In order to carry through this optimization task, we use stochastic relaxation with annealing. We prefer the Metropolis dynamics to the

  11. Annealing and the normalized N-cut

    Microsoft Academic Search

    Tomás Gedeon; Albert E. Parker; Collette Campion; Zane Aldworth

    2008-01-01

    We describe an annealing procedure that computes the normalized N -cut of a weighted graph G. The first phase transition computes the solution of the approximate normalized 2-cut problem, while the low temperature solution computes the normalized N -cut. The intermediate solutions provide a sequence of refinements of the 2-cut that can be used to split the data to K

  12. Multiple Sequence Alignment by Conformational Space Annealing

    Microsoft Academic Search

    Keehyoung Joo; Jinwoo Lee; Ilsoo Kim; Sung Jong Lee; Jooyoung Lee

    2008-01-01

    We present a new method for multiple sequence alignment (MSA), which we call MSACSA. The method is based on the direct application of a global optimization method called the conformational space annealing (CSA) to a consistency-based score function constructed from pairwise sequence alignments between constituting sequences. We applied MSACSA to two MSA databases, the 82 families from the BAliBASE reference

  13. Stochastic assembly line balancing using simulated annealing

    Microsoft Academic Search

    G. SURESH; S. SAHU

    1994-01-01

    The problem of balancing assembly lines with stochastic task processing times is addressed. The size of the problems that can be solved by optimal methods is limited and hence many heuristics have been developed, which give sub-optimal solutions. An approach for solving the problem using the simulated annealing technique is presented here. The proposed approach tries to reach the global

  14. Miniature ion-sorption vacuum pump with CNT field-emission electron source

    NASA Astrophysics Data System (ADS)

    Grzebyk, T.; Górecka-Drzazga, A.

    2013-01-01

    Generation and maintenance of the high vacuum in the MEMS-type (micro-electro-mechanical system) microsystems and vacuum nanoelectronics devices remain a major problem today. The phenomena of gas desorption from the surface of a microcavity and outgassing of materials limit the vacuum to the level of about 10-1 Pa. In this paper, a new MEMS-type micropump for generating a high vacuum in a microcavity is presented. The main component of the ion-sorption micropump is a carbon nanotube (CNT) field-emission electron source. Test structures of the electron source with electrophoretically deposited CNT have been fabricated and measured. A satisfactory value of the emission current and a low turn-on voltage have been obtained. The elaborated electron source has been applied to the micropump structure; it has enabled us to achieve a vacuum level below 10-3 Pa.

  15. Direct observation of vacuum fluctuations in a spinor Bose-Einstein condensate

    E-print Network

    Klempt, Carsten; Gebreyesus, Gebremedhn; Scherer, Manuel; Henninger, Thorsten; Hyllus, Philipp; Ertmer, Wolfgang; Santos, Luis; Arlt, Jan

    2009-01-01

    The nature of the vacuum state and its fluctuations constitutes one of the most fascinating aspects of modern physics. Despite their non-intuitive character, vacuum fluctuations play an important role for our understanding of nature. Specifically, the parametric amplification of such fluctuations is crucial for phenomena ranging from optical parametric down-conversion to stimulated positronium annihilation, and boson creation in Universe inflation. Spinor Bose-Einstein condensates, consisting of atoms with non-zero total spin, provide an optimal system for the investigation of the vacuum state, since vacuum fluctuations can dominate classical fluctuations in the spin dynamics of these magnetic superfluids. Here we explore the amplification of vacuum fluctuations in gaseous spinor condensates in an unstable spin configuration. We observe strong instability resonances in the spinor condensate, induced by the confinement of the atomic ensemble. Our work shows that it is crucial for the understanding of spinor dy...

  16. Observation of Vacuum Fluctuations in a Spinor Bose-Einstein Condensate

    NASA Astrophysics Data System (ADS)

    Klempt, C.; Topic, O.; Gebreyesus, G.; Scherer, M.; Henninger, T.; Hyllus, P.; Ertmer, W.; Santos, L.; Arlt, J.

    2010-02-01

    The nature of the vacuum state and its fluctuations constitutes one of the most fascinating aspects of modern physics. In particular, the parametric amplification of such fluctuations is crucial for phenomena ranging from optical parametric down-conversion1 to stimulated positronium annihilation,2 and boson creation in Universe inflation.3 Spinor Bose-Einstein condensates,4-7 consisting of atoms with non-zero total spin, provide an optimal system for the investigation of the vacuum state.8,9 Here we describe the amplification of vacuum fluctuations in gaseous spinor condensates in an unstable spin configuration. We observe strong instability resonances in the spinor condensate,10 induced by the confinement of the atomic ensemble. On these resonances we conclusively demonstrate that the system can act as a parametric amplifier for vacuum fluctuations,11 providing a new microscope to investigate the vacuum state and a promising method for entanglement and squeezing production in matter waves.

  17. Irradiation-induced phenomena in carbon

    E-print Network

    Krasheninnikov, Arkady V.

    Chapter 1 Irradiation-induced phenomena in carbon nanotubes To appear in "Chemistry of Carbon@acclab.helsinki.fi 1 #12;2CHAPTER 1. IRRADIATION-INDUCED PHENOMENA IN CARBON NANOTUBES #12;Contents 1 Irradiation-induced phenomena in carbon nanotubes 1 1.1 Introduction

  18. Groundwater phenomena and the theory of mixtures

    SciTech Connect

    Lee, D.W. (Oak Ridge National Lab., TN (USA)); Wineman, A.S. (Michigan Univ., Ann Arbor, MI (USA). Dept. of Mechanical Engineering and Applied Mechanics)

    1991-01-01

    The phenomena of groundwater motion and the recent developments in the Theory of Mixtures are reviewed. Comparisons of these results with those from classical theory are presented. Phenomena of interest that are not well explained are discussed and the potential of the Theory of Mixtures in addressing these phenomena is presented. 16 refs.

  19. Multifractal phenomena in physics and chemistry

    Microsoft Academic Search

    H. Eugene Stanley; Paul Meakin

    1988-01-01

    A brief introduction to multifractal phenomena, different regions of an object that have different fractal properties, is given. The application of the concept of multifractal phenomena to complex surfaces and interfaces and to fluid flow in porous media is discussed. Analogies of multifractals with thermodynamics and multifractal scaling are pointed out. The association of multifractal phenomena with systems where the

  20. Correlated randomness and switching phenomena

    NASA Astrophysics Data System (ADS)

    Stanley, H. E.; Buldyrev, S. V.; Franzese, G.; Havlin, S.; Mallamace, F.; Kumar, P.; Plerou, V.; Preis, T.

    2010-08-01

    One challenge of biology, medicine, and economics is that the systems treated by these serious scientific disciplines have no perfect metronome in time and no perfect spatial architecture-crystalline or otherwise. Nonetheless, as if by magic, out of nothing but randomness one finds remarkably fine-tuned processes in time and remarkably fine-tuned structures in space. Further, many of these processes and structures have the remarkable feature of “switching” from one behavior to another as if by magic. The past century has, philosophically, been concerned with placing aside the human tendency to see the universe as a fine-tuned machine. Here we will address the challenge of uncovering how, through randomness (albeit, as we shall see, strongly correlated randomness), one can arrive at some of the many spatial and temporal patterns in biology, medicine, and economics and even begin to characterize the switching phenomena that enables a system to pass from one state to another. Inspired by principles developed by A. Nihat Berker and scores of other statistical physicists in recent years, we discuss some applications of correlated randomness to understand switching phenomena in various fields. Specifically, we present evidence from experiments and from computer simulations supporting the hypothesis that water’s anomalies are related to a switching point (which is not unlike the “tipping point” immortalized by Malcolm Gladwell), and that the bubbles in economic phenomena that occur on all scales are not “outliers” (another Gladwell immortalization). Though more speculative, we support the idea of disease as arising from some kind of yet-to-be-understood complex switching phenomenon, by discussing data on selected examples, including heart disease and Alzheimer disease.

  1. R&D ERL: Vacuum

    SciTech Connect

    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 cryostat vacuum thermally insulating the SRF cavities need only reduce the convective heat load such that heat loss is primarily radiation through several layers of multi-layer insulation and conductive end-losses which are contained by 5{sup o}K thermal transitions. Prior to cool down rough vacuum {approx}10{sup -5} torr range is established and maintained by a dedicated turbomolecular pump station. Cryopumping by the cold mass and heat shields reduces the insulating vacuum to 10{sup -7} torr range after cool down.

  2. Surface Chemistry, Friction, and Wear Properties of Untreated and Laser-Annealed Surfaces of Pulsed-Laser-Deposited WS(sub 2) Coatings

    NASA Technical Reports Server (NTRS)

    Miyoshi, Kazuhisa; Wheeler, Donald R.; Zabinski, Jeffrey S.

    1996-01-01

    An investigation was conducted to examine the surface chemistry, friction, and wear behavior of untreated and annealed tungsten disulfide (WS2) coatings in sliding contact with a 6-mm-diameter 440C stainless-steel ball. The WS2 coatings and annealing were performed using the pulsed-laser-deposition technique. All sliding friction experiments were conducted with a load of 0.98 N (100 g), an average Hertzian contact pressure of 0.44 GPa, and a constant rotating speed of 120 rpm. The sliding velocity ranged from 31 to 107 mm/s because of the range of wear track radii involved in the experiments. The experiment was performed at room temperature in three environments: ultrahigh vacuum (vacuum pressure, 7X(exp -10) Pa), dry nitrogen (relative humidity, less than 1 percent), and humid air (relative humidity, 15 to 40 percent). Analytical techniques, including scanning electron microscopy (SEM), energy-dispersive x-ray spectroscopy (EDX), x-ray photo electron spectroscopy (XPS), surface profilometry, and Vickers hardness testing, were used to characterize the tribological surfaces of WS2 coatings. The results of the investigation indicate that the laser annealing decreased the wear of a WS2 coating in an ultrahigh vacuum. The wear rate was reduced by a factor of 30. Thus, the laser annealing increased the wear life and resistance of the WS2 coating. The annealed WS 2 coating had a low coefficient of friction (less than O.1) and a low wear rate ((10(exp -7) mm(exp 3)/N-m)) both of which are favorable in an ultrahigh vacuum.

  3. CW CO2-laser annealing of arsenic implanted silicon

    NASA Astrophysics Data System (ADS)

    Takai, M.; Tsien, P. H.; Tsou, S. C.; Röschenthaler, D.; Ramin, M.; Ryssel, H.; Ruge, I.

    1980-06-01

    CW CO2-laser annealing of arsenic implanted silicon was investigated in comparison with thermal annealing. Ion channeling, ellipsometry, and Hall effect measurements were performed to characterize the annealed layers and a correlation among the different methods was made. The laser annealing was done with power densities of 100 to 640 W cm-2 for 1 to 20 s. It was found that the lattice disorder produced during implantation can be completely annealed out by laser annealing with a power density of 500 W cm-2 and the arsenic atoms are brought on lattice sites up to 96±2%. The maximum sheet carrier concentration of 6×1015 cm-2 was obtained for 1×1016 cm-2 implantation after laser annealing, which was up to 33% higher than that after thermal annealing at 600 to 900°C for 30 min.

  4. High-Vacuum Annealing of Polythiophene:Methanofullerene Bulk Heterojunction Solar Cells

    Microsoft Academic Search

    Jennifer Segui; Ioana Gearba; Miriam Rafailovich; Charles Black

    2009-01-01

    Solar cell device architectures incorporating photoactive layers of immiscible blends of organic semiconductors achieve improved photovoltaic power conversion efficiency compared to planar device geometries. We have fabricated bulk heterojunction solar cells with active layer blends of poly-3 hexylthiophene (P3HT) and the fullerene derivative, [6,6] phenyl C61-butyric acid methyl ester (PCBM). Spin casting the blend from a chlorobenzene solution forms nanometer-scale

  5. Magnetism as the emergent phenomena

    NASA Astrophysics Data System (ADS)

    Tokura, Yoshinori

    2014-03-01

    Versatile emergent phenomena have been observed in strongly correlated electron systems as a consequence of mutual strong coupling among the spin, orbital, and charge degrees of freedom. Here, we would overview the outcomes of topological spin textures in transport, dielectric, and optical properties of correlated systems; these include sciences of colossal magnetoresistance, multiferroics, skyrmions, and topological/quantum-anomalous Hall effects. Impacts of the emergent electric and magnetic fields acting on the electrons in a solid are discussed as well as their possible applications to future devices.

  6. Quantum phenomena in gravitational field

    NASA Astrophysics Data System (ADS)

    Bourdel, Th.; Doser, M.; Ernest, A. D.; Voronin, A. Yu.; Voronin, V. V.

    2011-10-01

    The subjects presented here are very different. Their common feature is that they all involve quantum phenomena in a gravitational field: gravitational quantum states of ultracold antihydrogen above a material surface and measuring a gravitational interaction of antihydrogen in AEGIS, a quantum trampoline for ultracold atoms, and a hypothesis on naturally occurring gravitational quantum states, an Eötvös-type experiment with cold neutrons and others. Considering them together, however, we could learn that they have many common points both in physics and in methodology.

  7. Gravitational anomaly and transport phenomena.

    PubMed

    Landsteiner, Karl; Megías, Eugenio; Pena-Benitez, Francisco

    2011-07-01

    Quantum anomalies give rise to new transport phenomena. In particular, a magnetic field can induce an anomalous current via the chiral magnetic effect and a vortex in the relativistic fluid can also induce a current via the chiral vortical effect. The related transport coefficients can be calculated via Kubo formulas. We evaluate the Kubo formula for the anomalous vortical conductivity at weak coupling and show that it receives contributions proportional to the gravitational anomaly coefficient. The gravitational anomaly gives rise to an anomalous vortical effect even for an uncharged fluid. PMID:21797593

  8. Engineering of nanoscale defect patterns in CeO2 nanorods via ex situ and in situ annealing

    NASA Astrophysics Data System (ADS)

    Sakthivel, Tamil Selvan; Reid, David L.; Bhatta, Umananda M.; Möbus, Günter; Sayle, Dean C.; Seal, Sudipta

    2015-03-01

    Single-crystalline ceria nanorods were fabricated using a hydrothermal process and annealed at 325 °C-800 °C. As-synthesized CeO2 nanorods contain a high concentration of defects, such as oxygen vacancies and high lattice strains. Annealing resulted in an improved lattice crystalline quality along with the evolution of novel cavity-shaped defects in the nanorods with polyhedral morphologies and bound by e.g. {111} and {100} (internal) surfaces, confirmed for both air (ex situ) and vacuum (in situ) heating. We postulate that the cavities evolve via agglomeration of vacancies within the as-synthesized nanorods.Single-crystalline ceria nanorods were fabricated using a hydrothermal process and annealed at 325 °C-800 °C. As-synthesized CeO2 nanorods contain a high concentration of defects, such as oxygen vacancies and high lattice strains. Annealing resulted in an improved lattice crystalline quality along with the evolution of novel cavity-shaped defects in the nanorods with polyhedral morphologies and bound by e.g. {111} and {100} (internal) surfaces, confirmed for both air (ex situ) and vacuum (in situ) heating. We postulate that the cavities evolve via agglomeration of vacancies within the as-synthesized nanorods. Electronic supplementary information (ESI) available: W-H analysis result, the XPS spectrum of the annealed CeO2 nanorods, XPS binding energies of individual peaks, additional HRTEM images of as-synthesized CeO2 nanorods, and in situ TEM images in various places after heating. See DOI: 10.1039/c4nr07308h

  9. Vacuum vapor deposition

    NASA Technical Reports Server (NTRS)

    Poorman, Richard M. (inventor); Weeks, Jack L. (inventor)

    1995-01-01

    A method and apparatus is described for vapor deposition of a thin metallic film utilizing an ionized gas arc directed onto a source material spaced from a substrate to be coated in a substantial vacuum while providing a pressure differential between the source and the substrate so that, as a portion of the source is vaporized, the vapors are carried to the substrate. The apparatus includes a modified tungsten arc welding torch having a hollow electrode through which a gas, preferably inert, flows and an arc is struck between the electrode and the source. The torch, source, and substrate are confined within a chamber within which a vacuum is drawn. When the arc is struck, a portion of the source is vaporized and the vapors flow rapidly toward the substrate. A reflecting shield is positioned about the torch above the electrode and the source to ensure that the arc is struck between the electrode and the source at startup. The electrode and the source may be confined within a vapor guide housing having a duct opening toward the substrate for directing the vapors onto the substrate.

  10. Changing MFTF vacuum environment

    SciTech Connect

    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/sup 9/ to 5 x 10/sup 10/ particles per cc. The maximum leak rate of 10/sup -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.

  11. Motor actuated vacuum door

    NASA Astrophysics Data System (ADS)

    Hanagud, A. V.

    1986-10-01

    Doors that allow scientific instruments to record and retrieve the observed data are often required to be designed and installed as a part of sounding rocket hardware. The motor-actuated vacuum door was designed to maintain a medium vacuum of the order of 0.0001 torr or better while closed, and to provide an opening 15 inches long x 8.5 inches wide while open for cameras to image Halley's comet. When the electric motor receives the instruction to open the door through the payload battery, timer, and relay circuit, the first operation is to unlock the door. After unlatching, the torque transmitted by the motor to the main shaft through the links opens the door. A microswitch actuator, which rides on the linear motion conversion mechanism, is adjusted to trip the limit switch at the end of the travel. The process is repeated in the reverse order to close the door. 'O' rings are designed to maintain the seal. Door mechanisms similar to the one described have flown on Aerobee 17.018 and Black Brant 27.047 payloads.

  12. Influence of annealing condition and multicycle AlGaAs/GaAs structures on the Al0.26Ga0.74As surface morphology

    NASA Astrophysics Data System (ADS)

    Wei, Wenzhe; Wang, Yi; Guo, Xiang; Luo, Zijiang; Zhao, Zhen; Zhou, Haiyue; Ding, Zhao

    2015-08-01

    The influence of annealing temperature, As4 beam equivalent pressure and multi-runs growth on AlGaAs/GaAs structures was investigated. The real space ultrahigh vacuum scanning tunneling microscopy images showed that AlGaAs/GaAs surface morphology greatly depends on annealing conditions and initial state of surface. The reasons of the surface phenomenon are proposed, and a physical model was proposed to explain why the multi-runs growth structures can increase AlGaAs surface roughness. The reasonable preparation conditions for AlGaAs/GaAs structures were proposed.

  13. Processing of silicon solar cells by ion implantation and laser annealing

    NASA Technical Reports Server (NTRS)

    Minnucci, J. A.; Matthei, K. W.; Greenwald, A. C.

    1981-01-01

    Methods to improve the radiation tolerance of silicon cells for spacecraft use are described. The major emphasis of the program was to reduce the process-induced carbon and oxygen impurities in the junction and base regions of the solar cell, and to measure the effect of reduced impurity levels on the radiation tolerance of cells. Substrates of 0.1, 1.0 and 10.0 ohm-cm float-zone material were used as starting material in the process sequence. High-dose, low-energy ion implantation was used to form the junction in n+p structures. Implant annealing was performed by conventional furnace techniques and by pulsed laser and pulsed electron beam annealing. Cells were tested for radiation tolerance at Spire and NASA-LeRC. After irradiation by 1 MeV electrons to a fluence of 10 to the 16th power per sq cm, the cells tested at Spire showed no significant process induced variations in radiation tolerance. However, for cells tested at Lewis to a fluence of 10 to the 15th power per sq cm, ion-implanted cells annealed in vacuum by pulsed electron beam consistently showed the best radiation tolerance for all cell resistivities.

  14. Sb-Te alloy nanostructures produced on a graphite surface by a simple annealing process

    NASA Astrophysics Data System (ADS)

    Kuwahara, Masashi; Uratsuji, Hideaki; Abe, Maho; Sone, Hayato; Hosaka, Sumio; Sakai, Joe; Uehara, Yoichi; Endo, Rie; Tsuruoka, Tohru

    2015-08-01

    We have produced Sb-Te alloy nanostructures from a thin Sb2Te3 layer deposited on a highly oriented pyrolytic graphite substrate using a simple rf-magnetron sputtering and annealing technique. The size, shape, and chemical composition of the structures were investigated by scanning electron microscopy (SEM), atomic force microscopy (AFM), and energy dispersive X-ray spectrometry (EDX), respectively. The shape of the nanostructures was found to depend on the annealing temperature; nanoparticles appear on the substrate by annealing at 200 °C, while nanoneedles are formed at higher temperatures. Chemical composition analysis has revealed that all the structures were in the composition of Sb:Te = 1:3, Te rich compared to the target composition Sb2Te3, probably due to the higher movability of Te atoms on the substrate compared with Sb. We also tried to observe the production process of nanostructures in situ using SEM. Unfortunately, this was not possible because of evaporation in vacuum, suggesting that the formation of nanostructures is highly sensitive to the ambient pressure.

  15. Low partial discharge vacuum feedthrough

    NASA Technical Reports Server (NTRS)

    Benham, J. W.; Peck, S. R.

    1979-01-01

    Relatively discharge free vacuum feedthrough uses silver-plated copper conductor jacketed by carbon filled silicon semiconductor to reduce concentrated electric fields and minimize occurrence of partial discharge.

  16. Uranium Pyrophoricity Phenomena and Prediction

    SciTech Connect

    DUNCAN, D.R.

    2000-04-20

    We have compiled a topical reference on the phenomena, experiences, experiments, and prediction of uranium pyrophoricity for the Hanford Spent Nuclear Fuel Project (SNFP) with specific applications to SNFP process and situations. The purpose of the compilation is to create a reference to integrate and preserve this knowledge. Decades ago, uranium and zirconium fires were commonplace at Atomic Energy Commission facilities, and good documentation of experiences is surprisingly sparse. Today, these phenomena are important to site remediation and analysis of packaging, transportation, and processing of unirradiated metal scrap and spent nuclear fuel. Our document, bearing the same title as this paper, will soon be available in the Hanford document system [Plys, et al., 2000]. This paper explains general content of our topical reference and provides examples useful throughout the DOE complex. Moreover, the methods described here can be applied to analysis of potentially pyrophoric plutonium, metal, or metal hydride compounds provided that kinetic data are available. A key feature of this paper is a set of straightforward equations and values that are immediately applicable to safety analysis.

  17. Solar cells from laser-annealed ion-implanted silicon

    Microsoft Academic Search

    R. T. Young; C. W. White; J. Narayan; R. D. Westbrook; R. F. Wood; W. H. Christie

    1978-01-01

    Annealing by high-power laser pulses is being used to replace conventional furnace annealing for the removal of lattice damage in ion-implanted silicon. Results show that laser annealing can completely remove the lattice damage in the implanted layer without degradation of the minority carrier diffusion length in the substrate. This results in solar cells with improved open circuit voltages and short

  18. Transport properties of annealed CdSe colloidal nanocrystal solids

    Microsoft Academic Search

    M. Drndic; M. V. Jarosz; N. Y. Morgan; M. A. Kastner; M. G. Bawendi

    2002-01-01

    Transport properties of artificial solids composed of colloidal CdSe nanocrystals (NCs) are studied from 6 to 250 K, before and after annealing. After the solids are annealed, three changes are observed. First, transmission electron micrographs show that the separation between NCs decreases with annealing. Second, the optical absorption spectrum changes: the excitonic peaks of the NC solids shift to lower

  19. Motion of high-current vacuum arcs on spiral-type contacts

    Microsoft Academic Search

    EDGAR DULLNI

    1989-01-01

    Motion of vacuum arcs on spiral-type contacts is not only controlled by self-induced magnetic fields, but also by heating phenomena. An expression is derived which permits the calculation of the speed of the arc from a computation of the time needed to heat the surface up to boiling temperature. The heat flux density of the constricted arc at the anode

  20. The response of watercress ( Nasturtium officinale) to vacuum impregnation: Effect of an antifreeze protein type I

    Microsoft Academic Search

    Rui M. S. Cruz; Margarida C. Vieira; Cristina L. M. Silva

    2009-01-01

    The setting up of methodologies that reduce the size of ice crystals and reduce or inhibit the recrystallisation phenomena could have an extraordinary significance in the final quality of frozen products and consequently bring out new market opportunities. In this work, the effect of an antifreeze protein type I (AFP-I), by vacuum impregnation (VI), on frozen watercress was studied. The

  1. Numerical study on sublimation–condensation phenomena during microwave freeze drying

    Microsoft Academic Search

    Zhao Hui Wang; Ming Heng Shi

    1998-01-01

    A sublimation–condensation model is developed for freeze drying of unsaturated porous media. The governing equations describing the drying process are solved numerically with variable time step finite-difference method. The sublimation–condensation phenomena during microwave freeze drying are studied numerically for different operating conditions including electric field strength, sample thickness, and vacuum pressure. The results show that the sublimation–condensation effects depend on

  2. Control Dewar Secondary Vacuum Container

    SciTech Connect

    Rucinski, R.; /Fermilab

    1993-10-04

    This engineering note provides background information regarding the control dewar secondary vacuum container. The secondary vacuum container has it's origin with the CDP control dewar design. The name secondary vacuum container replaced the CDP term 'Watt can' which was named after Bob Watt (SLAC), a PAC/DOE review committee member who participated in a review of CDP and recommended a secondary vacuum enclosure. One of the most fragile parts of the control dewar design is the ceramic electrical feed throughs located in the secondary vacuum container. The secondary vacuum container is provided to guard against potential leaks in these ceramic insulating feed throughs. The secondary vacuum container has a pumping line separate from the main solenoid/control dewar insulating vacuum. This pumping line is connected to the inlet of the turbo pump for initial pumpdown. Under normal operation the container is isolated. Should a feedthrough develop a small leak, alternate pumping arrangements for the secondary vacuum container could be arranged. The pressure in the secondary vacuum container should be kept in a range that the breakdown voltage is kept at a maximum. The breakdown voltage is known to be a function of pressure and is described by a Paschen curve. I cannot find a copy of the curve at this time, but from what I remember, the breakdown voltage is a minimum somewhere around 10-3 torr. Ideally the pressure in the secondary vacuum can should be kept very low, around 10 E-6 or 10 E-7 torr for maximum breakdown voltage. If however a leak developed and this was not possible, then one could operate at a pressure higher than the minima point.

  3. Entrapment Type Vacuum Pumps

    NSDL National Science Digital Library

    This is a description for a learning module from Maricopa Advanced Technology Education Center. This PDF describes the module; access may be purchased by visiting the MATEC website. Entrapment type pumps operate primarily in the high to ultra-high vacuum ranges. The discussion in this MATEC module includes applications, theory of operation, operating range and preventative maintenance. The focus is on three major types of pumps: cryosorption, cryogenic and sputter-ion. The overall performance of these types of pumps depends on a variety of parameters. For example, it is important that learners understand the balance between pumping speed and capacity. Competency is demonstrated as the learners specify systems for defined process applications.

  4. Modeling Vacuum Arcs

    E-print Network

    Insepov, Z; Proslier, T; Huang, D; Mahalingam, S; Veitzer, S

    2010-01-01

    We are developing a model of vacuum arcs. This model assumes that arcs develop as a result of mechanical failure of the surface due to Coulomb explosions, followed by ionization of fragments by field emission and the development of a small, dense plasma that interacts with the surface primarily through self sputtering and terminates as a unipolar arc capable of producing breakdown sites with high enhancement factors. We have attempted to produce a self consistent picture of triggering, arc evolution and surface damage. We are modeling these mechanisms using Molecular Dynamics (mechanical failure, Coulomb explosions, self sputtering), Particle-In-Cell (PIC) codes (plasma evolution), mesoscale surface thermodynamics (surface evolution), and finite element electrostatic modeling (field enhancements). We can present a variety of numerical results. We identify where our model differs from other descriptions of this phenomenon.

  5. Annealing of Solar Cells and Other Thin Film Devices

    NASA Technical Reports Server (NTRS)

    Escobar, Hector; Kuhlman, Franz; Dils, D. W.; Lush, G. B.; Mackey, Willie R. (Technical Monitor)

    2001-01-01

    Annealing is a key step in most semiconductor fabrication processes, especially for thin films where annealing enhances performance by healing defects and increasing grain sizes. We have employed a new annealing oven for the annealing of CdTe-based solar cells and have been using this system in an attempt to grow US on top of CdTe by annealing in the presence of H2S gas. Preliminary results of this process on CdTe solar cells and other thin-film devices will be presented.

  6. 48 Optical Illusions & Visual Phenomena

    NSDL National Science Digital Library

    Have you ever wondered how different optical illusions work? This fun, informative, and very cool website developed by ophthalmologist Dr. Michael Bach of the University of Freiburg's Medical School introduces 48 interactive visual illusions and phenomena. The illusions are animated and accompanied by explanations that help visitors make sense of their perceptual responses. Major illusion categories include: Motion & Time, Luminance & Contrast, Colour, Cognitive, and more. The site is still in progress, and Dr. Bach encourages both general feedback, and additional scientific information for improving the illusion explanations. The second site, also from Professor Bach, presents site users with an interactive, online Visual Acuity Test. Note: The Contrast component of the Test has yet to be implemented.

  7. Cartridge getter for vacuum jacketing

    NASA Technical Reports Server (NTRS)

    Luebbers, C. J.

    1977-01-01

    Inexpensively-manufactured getter cartridge save users time in vacuum system maintenance and allows almost anyone to carry out replacement procedure that formerly required skilled welder. Cartridge screws into port in outer wall of vacuum jacket. Getter is replaced by simply unscrewing cartridge rather than cutting and rewelding.

  8. Technical specification for vacuum systems

    Microsoft Academic Search

    Khaw

    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 to 10¹¹ 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

  9. Anode modes in vacuum arcs

    Microsoft Academic Search

    H. Craig Miller

    1997-01-01

    This paper reviews the five different anode discharge modes which can occur in a vacuum arc. These modes are diffuse arc (low current, with or without anode sputtering), footpoint (intermediate current), and anode spot or intense arc (high current). Descriptions of the various modes are presented, based primarily on experimental results. The hot anode vacuum arc mode, which occurs only

  10. Computational Bottlenecks of Quantum Adiabatic Annealing

    NASA Astrophysics Data System (ADS)

    Knysh, Sergey

    2015-03-01

    Quantum annealing in a transverse field with rate d? / dt inversely proportional to the system size N suppresses non-adiabatic transitions for fully connected spin glass such as the Sherrington-Kirpatrick (SK) model at the quantum critical point. This alone is not sufficient to ensure that the problem is solvable in polynomial time. I conjecture the appearance of small gaps associated with macroscopic tunneling events deep in the spin glass phase. This effect is demonstrated rigorously for the annealing of a toy model that shares a set of crtical exponents with SK model: Hopfield network with two Gaussian patterns. It presents with 0 . 15 lnN additional bottlenecks with gaps that scale as a stretched exponential exp[-c (N?) 3 / 4]. Further, I extend the analysis to the ?-landscapes model (random energy model with correlations) which more faithfully represents real spin glasses.

  11. Simulated annealing for generalized Skyrme models

    NASA Astrophysics Data System (ADS)

    Longpré, J.-P.; Marleau, L.

    2005-05-01

    We use a simulated annealing algorithm to find the static field configuration with the lowest energy in a given sector of topological charge for generalized SU(2) Skyrme models. These numerical results suggest that the following conjecture may hold: the symmetries of the soliton solutions of extended Skyrme models are the same as for the Skyrme model. Indeed, this is verified for two effective Lagrangians with terms of order six and order eight in derivatives of the pion fields, respectively, for topological charges B=1 up to B=4. We also evaluate the energy of these multiskyrmions using the rational maps ansatz. A comparison with the exact numerical results shows that the reliability of this approximation for extended Skyrme models is almost as good as for the pure Skyrme model. Some details regarding the implementation of the simulated annealing algorithm in one and three spatial dimensions are provided.

  12. Vacuum energy as dark matter

    NASA Astrophysics Data System (ADS)

    Albareti, F. D.; Cembranos, J. A. R.; Maroto, A. L.

    2014-12-01

    We consider the vacuum energy of massive quantum fields in an expanding universe. We define a conserved renormalized energy-momentum tensor by means of a comoving cutoff regularization. Using exact solutions for de Sitter space-time, we show that in a certain range of mass and renormalization scales there is a contribution to the vacuum energy density that scales as nonrelativistic matter and that such a contribution becomes dominant at late times. By means of the WKB approximation, we find that these results can be extended to arbitrary Robertson-Walker geometries. We study the range of parameters in which the vacuum energy density would be compatible with current limits on dark matter abundance. Finally, by calculating the vacuum energy in a perturbed Robertson-Walker background, we obtain the speed of sound of density perturbations and show that the vacuum energy density contrast can grow on sub-Hubble scales as in standard cold dark matter scenarios.

  13. Spacetime structure and vacuum entanglement

    E-print Network

    Eduardo Martin-Martinez; Alexander R. H. Smith; Daniel R. Terno

    2015-07-09

    We study the role that both vacuum fluctuations and vacuum entanglement of a scalar field play in identifying the spacetime topology, which is not prescribed from first principles---neither in general relativity or quantum gravity. We analyze how the entanglement and observable correlations acquired between two particle detectors are sensitive to the spatial topology of spacetime. We examine the detector's time evolution to all orders in perturbation theory and then study the phenomenon of vacuum entanglement harvesting in Minkowski spacetime and two flat topologically distinct spacetimes constructed from identifications of the Minkowski space. We show that, for instance, if the spatial topology induces a preferred direction, this direction may be inferred from the dependence of correlations between the two detectors on their orientation. We therefore show that vacuum fluctuations and vacuum entanglement harvesting makes it, in principle, possible to distinguish spacetimes with identical local geometry that differ only in their topology.

  14. UV annealing of ultrathin tantalum oxide films

    Microsoft Academic Search

    J. J. Yu; J.-Y. Zhang; I. W. Boyd

    2002-01-01

    Tantalum pentoxide (Ta2O5) thin films with different thicknesses of around 100, 170 and 660Å have been grown on 4-in. p-type (100) Si wafers by photo-induced chemical vapor deposition and then annealed at low temperature (350°C) using 172nm excimer lamps. High film uniformity across the wafers with a thickness variation of not more than ±2.5% was readily achieved for all the

  15. Curve Fitting with NURBS using Simulated Annealing

    Microsoft Academic Search

    M. Sarfraz; M. Riyazuddin

    2004-01-01

    The global optimization strategy of Simulated Annealing is applied to the optimization of knot parameters of NURBS for curve\\u000a fitting, the objective being the reduction of fitting error to obtain a smooth curve. This is accomplished by using a unit\\u000a weight vector and a fixed number of control points calculated using the least squares technique, while the sum of squared

  16. Exemplar-Based Clustering via Simulated Annealing

    Microsoft Academic Search

    Michael J. Brusco; Hans-Friedrich Köhn

    2009-01-01

    Several authors have touted the p-median model as a plausible alternative to within-cluster sums of squares (i.e., K-means) partitioning. Purported advantages of the p-median model include the provision of “exemplars” as cluster centers, robustness with respect to outliers, and the accommodation\\u000a of a diverse range of similarity data. We developed a new simulated annealing heuristic for the p-median problem and

  17. Simulated annealing algorithm for optimal capital growth

    NASA Astrophysics Data System (ADS)

    Luo, Yong; Zhu, Bo; Tang, Yong

    2014-08-01

    We investigate the problem of dynamic optimal capital growth of a portfolio. A general framework that one strives to maximize the expected logarithm utility of long term growth rate was developed. Exact optimization algorithms run into difficulties in this framework and this motivates the investigation of applying simulated annealing optimized algorithm to optimize the capital growth of a given portfolio. Empirical results with real financial data indicate that the approach is inspiring for capital growth portfolio.

  18. Simulated annealing for supervised gene selection

    Microsoft Academic Search

    Maurizio Filippone; Francesco Masulli; Stefano Rovetta

    2011-01-01

    Genomic data, and more generally biomedical data, are often characterized by high dimensionality. An input selection procedure\\u000a can attain the two objectives of highlighting the relevant variables (genes) and possibly improving classification results.\\u000a In this paper, we propose a wrapper approach to gene selection in classification of gene expression data using simulated annealing\\u000a along with supervised classification. The proposed approach

  19. SPEECH INVERSE FILTERING BY SIMULATED ANNEALING ALGORITHM

    Microsoft Academic Search

    Chang-Shiann Wu; Yu-Fu Hsieh

    The purpose of this study is to develop one solution to the speech inverse filtering problem. A new efficient articulatory speech analysis scheme, identifying the articulatory parameters from the acoustic speech waveforms, was induced. The algorithm is known as simulated annealing, which is constrained to avoid non-unique solutions and local minima problems. The constraints are determined by the articulatory-to-acoustic transformation

  20. A new multiobjective simulated annealing algorithm

    Microsoft Academic Search

    Ozan Tekinalp; Gizem Karsli

    2007-01-01

    A new multiobjective simulated annealing algorithm for continuous optimization problems is presented. The algorithm has an\\u000a adaptive cooling schedule and uses a population of fitness functions to accurately generate the Pareto front. Whenever an\\u000a improvement with a fitness function is encountered, the trial point is accepted, and the temperature parameters associated\\u000a with the improving fitness functions are cooled. Beside well

  1. Rapid-thermal-annealing surface treatment for restoring the intrinsic properties of graphene field-effect transistors

    NASA Astrophysics Data System (ADS)

    Jang, Chan Wook; Kim, Ju Hwan; Kim, Jong Min; Shin, Dong Hee; Kim, Sung; Choi, Suk-Ho

    2013-10-01

    Graphene field-effect transistors (GFETs) were fabricated by photolithography and lift-off processes, and subsequently heated in a rapid-thermal-annealing (RTA) apparatus at temperatures (TA) from 200 to 400?° C for 10 min under nitrogen to eliminate the residues adsorbed on the graphene during the GFET fabrication processes. Raman-scattering, current-voltage (I-V), and sheet resistance measurements showed that, after annealing at 250?° C, graphene in GFETs regained its intrinsic properties, such as very small intensity ratios of D to G and G to 2D Raman bands, a symmetric I-V curve with respect to ˜0 V, and very low sheet resistance. Atomic force microscopy images and height profiles also showed that the surface roughness of graphene was almost minimized at TA = 250?° C. By annealing at 250?° C, the electron and hole mobilities reached their maxima of 4587 and 4605 cm2 V-1 s-1, respectively, the highest ever reported for chemical-vapor-deposition-grown graphene. Annealing was also performed under vacuum or hydrogen, but this was not so effective as under nitrogen. These results suggest that the RTA technique is very useful for eliminating the surface residues of graphene in GFETs, in that it employs a relatively low thermal budget of 250?° C and 10 min.

  2. Rapid-thermal-annealing surface treatment for restoring the intrinsic properties of graphene field-effect transistors.

    PubMed

    Jang, Chan Wook; Kim, Ju Hwan; Kim, Jong Min; Shin, Dong Hee; Kim, Sung; Choi, Suk-Ho

    2013-10-11

    Graphene field-effect transistors (GFETs) were fabricated by photolithography and lift-off processes, and subsequently heated in a rapid-thermal-annealing (RTA) apparatus at temperatures (T(A)) from 200 to 400 °C for 10 min under nitrogen to eliminate the residues adsorbed on the graphene during the GFET fabrication processes. Raman-scattering, current-voltage (I-V), and sheet resistance measurements showed that, after annealing at 250 °C, graphene in GFETs regained its intrinsic properties, such as very small intensity ratios of D to G and G to 2D Raman bands, a symmetric I-V curve with respect to ~0 V, and very low sheet resistance. Atomic force microscopy images and height profiles also showed that the surface roughness of graphene was almost minimized at T(A) = 250 °C. By annealing at 250 °C, the electron and hole mobilities reached their maxima of 4587 and 4605 cm(2) V(-1) s(-1), respectively, the highest ever reported for chemical-vapor-deposition-grown graphene. Annealing was also performed under vacuum or hydrogen, but this was not so effective as under nitrogen. These results suggest that the RTA technique is very useful for eliminating the surface residues of graphene in GFETs, in that it employs a relatively low thermal budget of 250 °C and 10 min. PMID:24029636

  3. Vacuum energy and cosmological evolution

    NASA Astrophysics Data System (ADS)

    Solà, Joan

    2014-07-01

    An expanding universe is not expected to have a static vacuum energy density. The so-called cosmological constant ? should be an approximation, certainly a good one for a fraction of a Hubble time, but it is most likely a temporary description of a true dynamical vacuum energy variable that is evolving from the inflationary epoch to the present day. We can compare the evolving vacuum energy with a Casimir device where the parallel plates slowly move apart ("expand"). The total vacuum energy density cannot be measured, only the effect associated to the presence of the plates, and then also their increasing separation with time. In the universe there is a nonvanishing spacetime curvature R as compared to Minkowskian spacetime that is changing with the expansion. The vacuum energy density must change accordingly, and we naturally expect ??˜R˜H2. A class of dynamical vacuum models that trace such rate of change can be constructed. They are compatible with the current cosmological data, and conveniently extended can account for the complete cosmic evolution from the inflationary epoch till the present days. These models are very close to the ?CDM model for the late universe, but very different from it at the early times. Traces of the inherent vacuum dynamics could be detectable in our recent past.

  4. Vacuum Brazing of Accelerator Components

    NASA Astrophysics Data System (ADS)

    Singh, Rajvir; Pant, K. K.; Lal, Shankar; Yadav, D. P.; Garg, S. R.; Raghuvanshi, V. K.; Mundra, G.

    2012-11-01

    Commonly used materials for accelerator components are those which are vacuum compatible and thermally conductive. Stainless steel, aluminum and copper are common among them. Stainless steel is a poor heat conductor and not very common in use where good thermal conductivity is required. Aluminum and copper and their alloys meet the above requirements and are frequently used for the above purpose. The accelerator components made of aluminum and its alloys using welding process have become a common practice now a days. It is mandatory to use copper and its other grades in RF devices required for accelerators. Beam line and Front End components of the accelerators are fabricated from stainless steel and OFHC copper. Fabrication of components made of copper using welding process is very difficult and in most of the cases it is impossible. Fabrication and joining in such cases is possible using brazing process especially under vacuum and inert gas atmosphere. Several accelerator components have been vacuum brazed for Indus projects at Raja Ramanna Centre for Advanced Technology (RRCAT), Indore using vacuum brazing facility available at RRCAT, Indore. This paper presents details regarding development of the above mentioned high value and strategic components/assemblies. It will include basics required for vacuum brazing, details of vacuum brazing facility, joint design, fixturing of the jobs, selection of filler alloys, optimization of brazing parameters so as to obtain high quality brazed joints, brief description of vacuum brazed accelerator components etc.

  5. Transfer-free graphene synthesis on insulating substrates via agglomeration phenomena of catalytic nickel films

    NASA Astrophysics Data System (ADS)

    Banno, Kazuya; Mizuno, Masaya; Fujita, Kazuhisa; Kubo, Toshiharu; Miyoshi, Makoto; Egawa, Takashi; Soga, Tetsuo

    2013-08-01

    Graphene layers were synthesized by annealing amorphous carbon (a-C) thin films on Ni/SiO2/Si(111) substrates grown using pulse arc plasma deposition. Although the graphene layers were formed by catalytic reaction between a-C films and Ni metals, they were observed to be directly on the insulating SiO2/Si substrates with island-shaped metallic particles. These particles presumably resulted from agglomeration phenomena of thin Ni films at a high temperature. We speculated that the agglomeration phenomena allowed the graphene formation on SiO2/Si substrates. It was also confirmed that the particle size and graphene layer thickness depend on the starting Ni thickness.

  6. Vacuum plasma spray coating

    NASA Technical Reports Server (NTRS)

    Holmes, Richard R.; Mckechnie, Timothy N.

    1989-01-01

    Currently, protective plasma spray coatings are applied to space shuttle main engine turbine blades of high-performance nickel alloys by an air plasma spray process. Originally, a ceramic coating of yttria-stabilized zirconia (ZrO2.12Y2O3) was applied for thermal protection, but was removed because of severe spalling. In vacuum plasma spray coating, plasma coatings of nickel-chromium-aluminum-yttrium (NiCrAlY) are applied in a reduced atmosphere of argon/helium. These enhanced coatings showed no spalling after 40 MSFC burner rig thermal shock cycles between 927 C (1700 F) and -253 C (-423 F), while current coatings spalled during 5 to 25 test cycles. Subsequently, a process was developed for applying a durable thermal barrier coating of ZrO2.8Y2O3 to the turbine blades of first-stage high-pressure fuel turbopumps utilizing the enhanced NiCrAlY bond-coating process. NiCrAlY bond coating is applied first, with ZrO2.8Y2O3 added sequentially in increasing amounts until a thermal barrier coating is obtained. The enchanced thermal barrier coating has successfully passed 40 burner rig thermal shock cycles.

  7. Changing MFTF vacuum environment

    SciTech Connect

    Margolies, D.; Valby, L.

    1982-08-19

    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/sup 9/ to 5 x 10/sup 10/ particles per cc. The maximum leak rate of 10/sup -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.

  8. Nucleation phenomena in polymeric systems

    NASA Astrophysics Data System (ADS)

    Binder, K.

    1995-02-01

    Materials formed from long flexible macromolecules differ from their small-molecule analogs, because corresponding collective length scales are distinctly larger and many dynamical phenomena are very much slower; in addition, the variation of chain length N yields a control parameter that leaves intermolecular forces invariant, but allows a stringent test of theories. These concepts are exemplified in a discussion of nucleation barriers for symmetrical polymer ( A, B)-mixtures (chain lengths NA = NB = N) near the critical temperature Tc, and for symmetrical block copolymers near the (fluctuation-induced) first order transition between the disordered melt and the lamellar mesophase. While in the latter case for N ? ? the transition becomes second-order and the order of magnitude of the nucleation barrier vanishes as N - {1}/{3}, for the polymer mixtures it increases as N {1}/{2} in the mean-field critical regime. Experiments and simulations, however, both show that very long chains are needed to fully reach this mean-field critical regime. For asymmetrical block copolymers {f= {N A}/{(N A+ N) }? {1}/{2}} the nucleation barrier scales as N {1}/{2}|f- {1}/{2}| 5.

  9. Bleed Hole Flow Phenomena Studied

    NASA Technical Reports Server (NTRS)

    1997-01-01

    Boundary-layer bleed is an invaluable tool for controlling the airflow in supersonic aircraft engine inlets. Incoming air is decelerated to subsonic speeds prior to entering the compressor via a series of oblique shocks. The low momentum flow in the boundary layer interacts with these shocks, growing in thickness and, under some conditions, leading to flow separation. To remedy this, bleed holes are strategically located to remove mass from the boundary layer, reducing its thickness and helping to maintain uniform flow to the compressor. The bleed requirements for any inlet design are unique and must be validated by extensive wind tunnel testing to optimize performance and efficiency. To accelerate this process and reduce cost, researchers at the NASA Lewis Research Center initiated an experimental program to study the flow phenomena associated with bleed holes. Knowledge of these flow properties will be incorporated into computational fluid dynamics (CFD) models that will aid engine inlet designers in optimizing bleed configurations before any hardware is fabricated. This ongoing investigation is currently examining two hole geometries, 90 and 20 (both with 5-mm diameters), and various flow features.

  10. Interference Phenomena in Quantum Information

    E-print Network

    Martin Stefanak

    2010-09-01

    One of the key features of quantum mechanics is the interference of probability amplitudes. The reason for the appearance of interference is mathematically very simple. It is the linear structure of the Hilbert space which is used for the description of quantum systems. In terms of physics we usually talk about the superposition principle valid for individual and composed quantum objects. So, while the source of interference is understandable it leads in fact to many counter-intuitive physical phenomena which puzzle physicists for almost hundred years. The present thesis studies interference in two seemingly disjoint fields of physics. However, both have strong links to quantum information processing and hence are related. In the first part we study the intriguing properties of quantum walks. In the second part we analyze a sophisticated application of wave packet dynamics in atoms and molecules for factorization of integers. The main body of the thesis is based on the original contributions listed separately at the end of the thesis. The more technical aspects and brief summaries of used methods are left for appendices.

  11. WESF natural phenomena hazards survey

    SciTech Connect

    Wagenblast, G.R., Westinghouse Hanford

    1996-07-01

    A team of engineers conducted a systematic natural hazards phenomena (NPH) survey for the 225-B Waste Encapsulation and Storage Facility (WESF). The survey is an assessment of the existing design documentation to serve as the structural design basis for WESF, and the Interim Safety Basis (ISB). The lateral force resisting systems for the 225-B building structures, and the anchorages for the WESF safety related systems were evaluated. The original seismic and other design analyses were technically reviewed. Engineering judgment assessments were made of the probability of NPH survival, including seismic, for the 225-B structures and WESF safety systems. The method for the survey is based on the experience of the investigating engineers,and documented earthquake experience (expected response) data.The survey uses knowledge on NPH performance and engineering experience to determine the WESF strengths for NPH resistance, and uncover possible weak links. The survey, in general, concludes that the 225-B structures and WESF safety systems are designed and constructed commensurate with the current Hanford Site design criteria.

  12. Vacuum Function Operation and Systems

    NSDL National Science Digital Library

    The understanding of vacuum function and systems is essential for students and employees working within the micro- and nanofabrication industry. This presentation/webinar highlights the use, construction, and examples of current vacuum technology systems today. Prepared by WHO, of the Nanotechnology Applications and Career Knowledge (NACK), a National ATE Center, this presentation provides material presented from the instructor/engineer viewpoint. Discussions include vacuum pump function, gauge use and ranges, applicable design considerations, as well as insight on cost and equipment training methodologies that have been utilized by the NACK Center. This site requires a free log-in to access.

  13. Microstructure evolution during annealing of TiAl/NiCoCrAl multilayer composite prepared by EB-PVD

    SciTech Connect

    Zhang, Rubing, E-mail: zrb86411680@126.com [Department of Mechanics, School of Civil Engineering, Beijing Jiaotong University, Beijing 100044 (China); Zhang, Deming [Beijing General Research Institute of Mining and Metallurgy, Beijing 100044 (China); Chen, Guiqing [Center for Composite Materials, Harbin Institute of Technology, Harbin 150001 (China); Wang, Yuesheng [Department of Mechanics, School of Civil Engineering, Beijing Jiaotong University, Beijing 100044 (China)

    2014-07-01

    TiAl/NiCoCrAl laminate composite sheet with a thickness of 0.4–0.6 mm as well as a dimension of 150 mm × 100 mm was fabricated successfully by using electron beam physical vapor deposition (EB-PVD) method. The annealing treatment was processed at 1123 and 1323 K for 3 h in a high vacuum atmosphere, respectively. The phase composition and microstructure of TiAl/NiCoCrAl microlaminated sheet have been analyzed by X-ray diffraction (XRD), scanning electron microscopy (SEM) and transmission electron microscopy (TEM). Based on the sheet characterization and results of the microstructure evolution during annealing treatment process, the diffusion mechanism of interfacial reaction in TiAl/NiCoCrAl microlaminate was investigated and discussed.

  14. Effects of nickel ions implantation and subsequent thermal annealing on structural and magnetic properties of titanium dioxide

    NASA Astrophysics Data System (ADS)

    Vakhitov, I. R.; Lyadov, N. M.; Valeev, V. F.; Nuzhdin, V. I.; Tagirov, L. R.; Khaibullin, R. I.

    2014-12-01

    Wide bandgap semiconducting rutile (TiO2) doped with 3d-elements is a promising material for spintronic applications. In our work a composite material of TiO2:Ni has been formed by using implantation of Ni+ ions into single-crystalline (100)- and (001)- plates of TiO2. Sub-micron magnetic layers of TiO2 containing nickel dopant have been obtained at high implantation fluence of 1×1017 ion/cm2. A part of the implanted samples was then annealed in vacuum at different temperatures Tann = 450-1200 K for 30 min. The influence of the implantation fluence, crystalline orientation, as well as subsequent annealing on the structural and magnetic properties of the nickel-implanted TiO2 have been investigated by using X-ray photoelectron spectroscopy, scanning electron microscopy and coil magnetometry techniques.

  15. Enhancing the photocatalytic efficiency of sprayed ZnO thin films through double doping (Sn + F) and annealing under different ambiences

    NASA Astrophysics Data System (ADS)

    Ravichandran, K.; Mohan, R.; Sakthivel, B.; Varadharajaperumal, S.; Devendran, P.; Alagesan, T.; Pandian, K.

    2014-12-01

    Doubly (Sn + F) doped zinc oxide (ZnO:Sn:F) thin films were deposited onto glass substrates using a simplified spray pyrolysis technique. The deposited films were annealed at 400 °C under two different ambiences (air and vacuum) for 2 h. The photocatalytic activity of these films was assessed through photocatalytic decolorization kinetics of Methylene Blue (MB) dye and the decolorization efficiency of the annealed films was compared with that of their as-deposited counterpart. The photocatalytic studies reveal that the ZnO:Sn:F films annealed under vacuum environment exhibits better photocatalytic efficiency when compared with both air annealed and as-deposited films. The SEM and TEM images depict that the surface of each of the films has an overlayer comprising of nanobars formed on a bottom layer, having spherical grains. The studies show that the diameter of the nanobars plays crucial role in enhancing the photocatalytic activity of the ZnO:Sn:F films. The structural, optical and electrical studies substantiate the discussions on the photocatalytic ability of the deposited films.

  16. Pollution prevention in vacuum processes

    SciTech Connect

    Mulholland, K.L.; Dyer, J.A. [E.I. du Pont de Nemours and Co., Wilmington, DE (United States)] [E.I. du Pont de Nemours and Co., Wilmington, DE (United States)

    1999-05-01

    The gaseous emissions from vacuum systems often contain volatile organic compounds (VOCs)--one or more of which may be regulated as Hazardous Air Pollutants (HAPs) under the 1990 Clean Air Act Amendments. Typically, regulated emission sources will require greater than 98% control of using an end-of-pipe abatement or recovery technology. VOCs from vacuum generation are expensive to control and increase the investment and operating cost of the vacuum system. When noncondensibles or inerts are present, the amount of VOCs emitted to the environment will increase dramatically. This article discusses approaches which process and project engineers can apply to reduce or eliminate vacuum system emissions. Actual case histories are included which reflect the range of solutions that are being applied.

  17. Alumina barrier for vacuum brazing

    NASA Technical Reports Server (NTRS)

    Beuyukian, C. S.

    1980-01-01

    Heating platens of vacuum-brazing press will not stick to workpiece if aluminum oxide "paper" is interposed. Paper does not disintegrate in press, will not contaminate braze alloy, and helps form smoothly contoured, regular fillet at brazed edges.

  18. Vacuum Energy in Quantum Graphs

    E-print Network

    Wilson, Justin

    2007-07-14

    energy density. Both methods are done heuristically for star graphs then rigorously for general graphs. We also discuss some properties of the vacuum energy in quantum graphs including: repulsive Casimir forces, convergence and continuity in bond lengths....

  19. Ranking significant phenomena in physical systems

    Microsoft Academic Search

    R. A. Dimenna; T. K. Larson

    1989-01-01

    The analysis of any physical system requires a thorough understanding of the principal phenomena affecting the behavior of that system. In a complex application such as a nuclear reactor, identifying the principal phenomena in an accident transient can be a formidable task. This paper describes the use of the analytical hierarchy process (AHP) to assimilate engineering judgments that relate and

  20. Thermoelectric phenomena via an interacting particle system

    E-print Network

    Maes, Christian

    Thermoelectric phenomena via an interacting particle system Christian Maes and Maarten H. van for thermoelectric phenomena in terms of an interacting particle system, a lattice electron gas dynamics, a standard reference is [1]. We present an interacting particle system for the standard thermoelectric

  1. Stochastic properties of partial-discharge phenomena

    Microsoft Academic Search

    R. J. Van Brunt

    1991-01-01

    The author presents a bibliography and survey of the literature concerned with theory and measurement of the stochastic behavior of pulsating partial-discharge (PD) phenomena that can occur when insulation is subjected to electrical stress. The types of PD phenomena considered include AC and DC generated electron avalanches, pulsating positive and negative corona in gases, and PD that occur in liquid

  2. Critical Phenomena in Multi-scale Models

    Microsoft Academic Search

    E. A. Shchepakina; V. A. Sobolev

    The paper is devoted to the investigation of the relationship between slow integral manifolds of singularly perturbed dierential equations and critical phenomena in chemical kinetics and laser models. We tried to consider dierent problems using the techniques of canards and black swans. The mathematical language of singular perturbations seems to apply to all critical phenomena even in the most disparate

  3. Quantum versus Classical Annealing of Ising Spin Glasses

    E-print Network

    Bettina Heim; Troels F. Rønnow; Sergei V. Isakov; Matthias Troyer

    2014-11-20

    The strongest evidence for superiority of quantum annealing on spin glass problems has come from comparing simulated quantum annealing using quantum Monte Carlo (QMC) methods to simulated classical annealing [G. Santoro et al., Science 295, 2427(2002)]. Motivated by experiments on programmable quantum annealing devices we revisit the question of when quantum speedup may be expected for Ising spin glass problems. We find that even though a better scaling compared to simulated classical annealing can be achieved for QMC simulations, this advantage is due to time discretization and measurements which are not possible on a physical quantum annealing device. QMC simulations in the physically relevant continuous time limit, on the other hand, do not show superiority. Our results imply that care has to be taken when using QMC simulations to assess quantum speedup potential and are consistent with recent arguments that no quantum speedup should be expected for two-dimensional spin glass problems.

  4. Fourier-transforming with quantum annealers

    NASA Astrophysics Data System (ADS)

    Hen, Itay

    2014-07-01

    We introduce a set of quantum adiabatic evolutions that we argue may be used as `building blocks', or subroutines, in the onstruction of an adiabatic algorithm that executes Quantum Fourier Transform (QFT) with the same complexity and resources as its gate-model counterpart. One implication of the above construction is the theoretical feasibility of implementing Shor's algorithm for integer factorization in an optimal manner, and any other algorithm that makes use of QFT, on quantum annealing devices. We discuss the possible advantages, as well as the limitations, of the proposed approach as well as its relation to traditional adiabatic quantum computation.

  5. Optimised simulated annealing for Ising spin glasses

    NASA Astrophysics Data System (ADS)

    Isakov, S. V.; Zintchenko, I. N.; Rønnow, T. F.; Troyer, M.

    2015-07-01

    We present several efficient implementations of the simulated annealing algorithm for Ising spin glasses on sparse graphs. In particular, we provide a generic code for any choice of couplings, an optimised code for bipartite graphs, and highly optimised implementations using multi-spin coding for graphs with small maximum degree and discrete couplings with a finite range. The latter codes achieve up to 50 spin flips per nanosecond on modern Intel CPUs. We also compare the performance of the codes to that of the special purpose D-Wave devices built for solving such Ising spin glass problems.

  6. A study of magnetically annealed ferromagnetic materials 

    E-print Network

    Ramos, Domingo

    1961-01-01

    August 1961 ASST RACT The factors that affect the magnetic properties of ferromagnetic materials and conrentional methods of preparation of ferrites" are re- viewed briefly. A new processing metf od by magnetic annealing for the prepara- tion... of ferrites is presented. Specimens made from several compositions of Ni: Zn: Fe&O4 and (Nil . Zn &:Co:Fe204 in powdered form were x' y' Z 4 ' 1-x x'1-y' y' heat treated in a magnetic field. The specimens were cylindrical in shape and i:ad three electrical...

  7. Cold cathode vacuum gauging system

    DOEpatents

    Denny, Edward C. (Knoxville, TN)

    2004-03-09

    A vacuum gauging system of the cold cathode type is provided for measuring the pressure of a plurality of separate vacuum systems, such as in a gas centrifuge cascade. Each casing is fitted with a gauge tube assembly which communicates with the vacuum system in the centrifuge casing. Each gauge tube contains an anode which may be in the form of a slender rod or wire hoop and a cathode which may be formed by the wall of the gauge tube. The tube is provided with an insulated high voltage connector to the anode which has a terminal for external connection outside the vacuum casing. The tube extends from the casing so that a portable magnet assembly may be inserted about the tube to provide a magnetic field in the area between the anode and cathode necessary for pressure measurements in a cold cathode-type vacuum gauge arrangement. The portable magnetic assembly is provided with a connector which engages the external high voltage terminal for providing power to the anode within in the gauge tube. Measurement is made in the same manner as the prior cold cathode gauges in that the current through the anode to the cathode is measured as an indication of the pressure. By providing the portable magnetic assembly, a considerable savings in cost, installation, and maintenance of vacuum gauges for pressure measurement in a gas centrifuge cascade is realizable.

  8. Tunneling through high energy barriers in simulated quantum annealing

    E-print Network

    Elizabeth Crosson; Mingkai Deng

    2014-10-30

    We analyze the performance of simulated quantum annealing (SQA) on an optimization problem for which simulated classical annealing (SA) is provably inefficient because of a high energy barrier. We present evidence that SQA can pass through this barrier to find the global minimum efficiently. This demonstrates the potential for SQA to inherit some of the advantages of quantum annealing (QA), since this problem has been previously shown to be efficiently solvable by quantum adiabatic optimization.

  9. Computerized simulation of thermal annealing effects on self implanted silicon

    SciTech Connect

    De Sandre, G. [Politecnico di Milano (Italy). Dipartimento di Ingegneria Nucleare; Colombo, L. [Universita` di Milano (Italy). Dipartimento di Fisica; Maric, D. [CSCS, Manno (Switzerland)

    1995-09-01

    The authors investigate the effects of thermal annealing on the structural, elastic and electronic properties of self implanted silicon by tight binding molecular dynamics. The irradiated samples, after a careful relaxation at room temperature, are annealed at different temperatures and for different times and, finally, their properties are carefully monitored during constant temperature simulations. They further provide a characterization of the chemical bonding in the amorphous network and show the evolution of the point defect distribution against maximum annealing temperature.

  10. Fission Gas Release during Post Irradiation Annealing of BWR Fuels

    Microsoft Academic Search

    Katsumi UNE; Shinji KASHIBE

    1990-01-01

    Uranium dioxide fuels irradiated in a commercial BWR during 1 to 4 cycles (burn-up: 6–28 GWd\\/t) have been annealed in an out-of-pile condition and the release rate of Kr was measured continuously. The annealing temperature ranged 1,500–1,800°C. The effects of temperature and burn-up have been studied on burst release during temperature ramp and on diffusional release during isothermal annealing.The burst

  11. Simulated Q-annealing: conformational search with an effective potential

    Microsoft Academic Search

    Won-joon Son; Soonmin Jang; Seokmin Shin

    We have tested a version of the generalized simulated annealing algorithm based on molecular dynamics simulations with effective\\u000a potential suggested by Tsallis statistics. The generalized annealing method, termed “simulated Q-annealing (SQ),” is applied\\u000a to the simulations of a synthetic 11-residue peptide segment (1AQG). In SQ, the energy barriers between local minima change\\u000a as the parameter q is varied and specific

  12. Effect of thermal annealing on structure and optical band gap of Se66Te25In9 thin films

    NASA Astrophysics Data System (ADS)

    Dwivedi, D. K.; Pathak, H. P.; Shukla, Nitesh; Kumar, Vipin

    2015-05-01

    Thin films of a-Se66Te25In9 have been deposited onto a chemically cleaned glass substrate by thermal evaporation technique under vacuum. Glassy nature of the films has been ascertained by X-ray diffraction pattern. The analysis of absorption spectra, measured at normal incidence, in the spectral range 400-1100 nm has been used for the optical characterization of thin films under investigation. The effect of thermal annealing on structure and optical band gap (Eg) of a-Se66Te25In9 have been studied.

  13. Recrystallization phenomena in an IF steel observed by in situ EBSD experiments.

    PubMed

    Nakamichi, H; Humphreys, F J; Brough, I

    2008-06-01

    In situ electron backscatter diffraction microstructural analysis of recrystallizing interstitial free steels deformed to strains of 0.75 and 1.6 has been carried out in a FEG-SEM. The experimental procedures are discussed, and it is shown that there is no degradation of the electron backscatter diffraction patterns at temperatures up to 800 degrees C. Analysis of the surface and interior microstructures of annealed samples shows only minor difference, which suggests that in situ annealing experiments are of value. In addition, it is shown that in situ measurements allow a detailed comparison between the same areas before and after annealing, thereby providing information about the recrystallization mechanisms. Sequential recrystallization phenomena, such as initiation and growth of new grains, are observed at temperatures over 740 degrees C, and depending on the deformation histories, different recrystallization behaviour is observed. It is found that {111} <123> recrystallized grains are preferentially formed in the highly deformed material, whereas no strong recrystallization texture is formed in the lower strained material. PMID:18503673

  14. Proton damage annealing for use in extended life solar arrays

    NASA Astrophysics Data System (ADS)

    Day, A. C.; Horne, W. E.; Arimura, I.

    1980-12-01

    Isochronal and isothermal annealing studies have been performed on low energy (250 keV and 1.5 MeV) proton damage in silicon and gallium arsenide solar cells. It is found that (1) proton damaged silicon cells can be restored to within 90-95% of their initial maximum power in less than five minutes at 400 C; (2) damaged gallium arsenide cells anneal more slowly and do not recover as completely at temperatures up to 300 C where thermal degradation is observed; and (3) the annealing of silicon cells exhibits a dependence on fluence, suggesting that a tradeoff exists between frequency of anneals and other economic factors.

  15. Teaching vacuum technology using spreadsheet calculations

    Microsoft Academic Search

    R. E. Pearson; G. M. Atkinson

    2003-01-01

    Vacuum technology is an important part of nano-fabrication. Automated control systems for vacuum equipment have made operation easy and safe but have also isolated the user from the need to understand the physics of vacuum systems. In spite of this, many equipment and process decisions revolve around choices made concerning the vacuum components of a processing tool. Students can use

  16. Leak rate measurements for large vacuum chambers

    Microsoft Academic Search

    HE Nuss; I Streuff

    1995-01-01

    For large vacuum chambers of volume between 50 and 500 m3, which are required for space simulation and thermal vacuum testing of spacecraft systems and subsystems, a specific method for the determination of the vacuum chamber leak rate is described. The main characteristics of the facility including irradiation, thermal shroud, motion and vacuum subsystem are presented. The outgassing and desorption

  17. Cold-Cathodes for Sensors and Vacuum Microelectronics

    SciTech Connect

    Siegal, M.P.; Sullivan, J.P.; Tallant, D.R.; Simpson, R.L. [Sandia National Labs., Albuquerque, NM (United States); DiNardo, N.J.; Mercer, T.W. [Drexel Univ., Philadelphia, PA (United States). Dept. of Physics and Astronomy; Martinez-Miranda, L.J. [Univ. of Maryland, College Park, MD (United States). Dept. of Materials Science and Engineering

    1998-05-01

    The aim of this laboratory-directed research and development project was to study amorphous carbon (a-C) thin films for eventual cold-cathode electron emitter applications. The development of robust, cold-cathode emitters are likely to have significant implications for modern technology and possibly launch a new industry: vacuum micro-electronics (VME). The potential impact of VME on Sandia`s National Security missions, such as defense against military threats and economic challenges, is profound. VME enables new microsensors and intrinsically radiation-hard electronics compatible with MOSFET and IMEM technologies. Furthermore, VME is expected to result in a breakthrough technology for the development of high-visibility, low-power flat-panel displays. This work covers four important research areas. First, the authors studied the nature of the C-C bonding structures within these a-C thin films. Second, they determined the changes in the film structures resulting from thermal annealing to simulate the effects of device processing on a-C properties. Third, they performed detailed electrical transport measurements as a function of annealing temperature to correlate changes in transport properties with structural changes and to propose a model for transport in these a-C materials with implications on the nature of electron emission. Finally, they used scanning atom probes to determine important aspects on the nature of emission in a-C.

  18. Wave phenomena in phononic crystals

    NASA Astrophysics Data System (ADS)

    Sukhovich, Alexey

    Novel wave phenomena in two- and three-dimensional (2D and 3D) phononic crystals were investigated experimentally using ultrasonic techniques. These ultrasonic techniques allow the full wave field to be imaged directly, which is a considerable advantage in fundamental studies of wave propagation in periodic media. Resonant tunnelling of ultrasonic waves was successfully observed for the first time by measuring the transmission of ultrasound pulses through a double barrier consisting of two 3D phononic crystals separated by a cavity. This effect is the classical analogue of resonant tunnelling of a quantum mechanical particle through a double potential barrier, in which transmission reaches unity at resonant frequencies. For phononic crystals, the tunnelling peak was found to be less than unity, an effect that was explained by absorption. Absorption introduces a small propagating component inside the crystals in addition to the dominant evanescent mode at band gap frequencies, and causes leakage of the pulse from the cavity. The dynamics of resonant tunnelling was explored by measuring the group velocities of the ultrasonic pulses. Very slow and very fast velocities were found at frequencies close to and at the resonance, respectively. These extreme values are less than the speed of sound in air and greater than the speed of sound in any of the crystal's constituent materials. Negative refraction and focusing effects in 2D phononic crystals were also observed. Negative refraction of ultrasound was demonstrated unambiguously in a prism-shaped 2D crystal at frequencies in the 2nd pass band, where the equifrequency contours are circular so that the wave vector and group velocity are antiparallel. The Multiple Scattering Theory and Snell's law allowed theoretical predictions of the refraction angles. Excellent agreement was found between theory and experiment. The negative refraction experiments revealed a mechanism that can be used to focus ultrasound using a flat phononic crystal, and experiments to demonstrate the focusing of ultrasound emitted by several point sources were successfully carried out. The importance of using phononic crystals with circular equi frequency contours, as well as matching the size of the contours inside and outside the crystal, was established. Both conditions were satisfied by a flat phononic crystal of steel rods, in which the liquid inside the crystal (methanol) was different from the outside medium (water). The possibility of achieving subwavelength resolution using this phononic crystal was investigated with a subwavelength line source (a miniature strip-shaped transducer, approximately lambda/5 wide). A resolution of 0.55lambda was found, which is just above the diffraction limit lambda/2.

  19. Annealing Would Improve beta" - Alumina Solid Electrolyte

    NASA Technical Reports Server (NTRS)

    Williams, Roger; Homer, Margie; Ryan, Margaret; Cortez, Roger; Shields, Virgil; Kisor, Adam

    2003-01-01

    A pre-operational annealing process is under investigation as a potential means of preventing a sudden reduction of ionic conductivity in a Beta"-alumina solid electrolyte (BASE) during use. On the basis of tests, the sudden reduction of ionic conductivity, followed by a slow recovery, has been found to occur during testing of the solid electrolyte and electrode components of an alkali metal thermal-to-electric converter (AMTEC) cell. At this time, high-temperature tests of limited duration have indicated the superiority of the treated BASE, but reproducible tests over thousands of hours are necessary to confirm that microcracking has been eliminated. The ionic conductivity of the treated BASE is also measured to be higher than untreated BASE at 1,073 K in low-pressure sodium vapor. Microcracking resulting in loss of conductivity was not observed with treated BASE in one high-temperature experiment, but this result must be duplicated over very long testing times to be sure of the effect. Shorter annealing times (10 to 20 hours) were found to result in significantly less loss of mass; it may be necessary for the packed powder mixture to evolve some Na2O before the Na2O can leave the ceramic.

  20. Annealing and thickness effect on the optical absorption of Ge20Te80 and Cu6Ge14Te80 films

    NASA Astrophysics Data System (ADS)

    El-Zahed, H.; Dongol, M.; Radwan, M.

    2002-03-01

    Thin films of Ge{20}Te{80} and Cu6Ge{14}Te{80} of different thicknesses are deposited on glass substrate by thermal evaporation under vacuum. The effect of incorporation of copper in Ge{20}Te{80} film is studied by measuring the optical absorption. The mechanism of optical absorption follows the rule of direct transition. The films are annealed at different elevated temperatures from 370 to 520 K. The measurements were carried on as-deposited and annealed specimens. The optical energy gap (E_g) was found to decrease with increasing the annealing temperatures in the case of Ge{20}Te{80} films. But in the case of Cu6Ge{14}Te{80} films, E_g first increases with annealing temperature up to 410 K, then decreases sharply after further increasing the annealing temperature above the glass transition temperature. The decreases of E_g and the increase of the width of localized states E_e could be attributed to the amorphous - crystalline transformation. The values of optical energy gap E_g are also found to increase with thickness of both two-type films. The effect of films thickness on optical energy gap (E_g) of the films is interpreted in terms of the density of state model of Mott and Davis. The refractive index n, extinction coefficient k and dielectric constant \\varepsilon_i and \\varepsilon_r are also calculated for all samples.

  1. Effect of electron beam rapid thermal annealing on crystallographic, structural and magnetic properties of Zn1-xSmxO thin films

    NASA Astrophysics Data System (ADS)

    Sundararaj, Anuraj; Chandrasekaran, Gopalakrishnan; Annal Therese, Helen; Sonachalam, Arumugam; Annamalai, Karthigeyan

    2015-03-01

    Trivalent rare earth ions (Sm3+) doped ZnO dilute magnetic semiconductor thin films (Zn1-xSmxO, where x=0.02, 0.04 and 0.06) of different thickness are grown on silicon (100) substrates using radio frequency magnetron sputtering and post annealed in high vacuum by electron beam rapid thermal annealing (ERTA) technique. X-ray diffraction analysis indicates that the thin films have a ZnO's hexagonal wurtzite structure. The unit cell constants a, c and the cell volume increases in the as-deposited sample as 'x' increases, whereas ERTA has a reverse effect on them. Topographic analysis by atomic force microscopy on as-deposited thin films shows nonlinear change in grain size as a function of Sm concentration, whereas annealed thin films show linear change. Magnetization studies by vibrating sample magnetometer on as-deposited and annealed Zn1-xSmxO thin films show ferromagnetic response, due to the oxygen vacancies introduced by Sm doping. The as-deposited 100 nm Zn0.94Sm0.06O thin film is weakly ferromagnetic (24 ?emu), which after annealing becomes comparatively stronger (60 ?emu). This indicates that apart from higher doping concentration of Sm, ERTA plays an important role in inducing oxygen vacancies.

  2. Study of the optical properties of etched alpha tracks in annealed and non-annealed CR-39 polymeric detectors

    NASA Astrophysics Data System (ADS)

    Saad, A. F.; Al-Faitory, N. M.; Mohamed, R. A.

    2014-04-01

    The UV-visible absorption spectra of virgin and alpha particle-irradiated, annealed and non-annealed CR-39 polymeric track detectors were investigated using a UV-visible spectrometer (Shimadzu mini 1240). Isothermal annealing experiments were carried out on poly allyl diglycol carbonate (PADC) films based nuclear track detectors (NTDs) exposed to a 241Am source. A shifting and broadening of the UV-visible peaks was observed as a result of the etched alpha tracks in the non-annealed and annealed PADC films. The UV-visible spectra of the virgin and non-annealed ?-irradiated PADC polymer films displayed a decreasing trend in their optical energy band gaps, both direct and indirect, whereas those measured for the annealed ?-irradiated ones showed no significant change. This drop in the energy band gap with increasing fluence is discussed on the basis of the alpha particle- and thermal annealing-induced modifications in the PADC polymeric detector. The results clearly showed that the values for the indirect energy band gap were lower than the corresponding values for the direct band gap. In addition, the Urbach energy was estimated from the Urbach edge, and exhibited roughly the same trend as the optical band gap. Finally, this study presents new results showing that the annealed PADC films were highly insensitive to alpha particles.

  3. Probability distribution of the vacuum energy density

    E-print Network

    G. Duplancic; D. Glavan; H. Stefancic

    2010-11-26

    As the vacuum state of a quantum field is not an eigenstate of the Hamiltonian density, the vacuum energy density can be represented as a random variable. We present an analytical calculation of the probability distribution of the vacuum energy density for real and complex massless scalar fields in Minkowski space. The obtained probability distributions are broad and the vacuum expectation value of the Hamiltonian density is not fully representative of the vacuum energy density.

  4. Probability distribution of the vacuum energy density

    SciTech Connect

    Duplancic, Goran; Stefancic, Hrvoje [Theoretical Physics Division, Rudjer Boskovic Institute, P.O. Box 180, HR-10002 Zagreb (Croatia); Glavan, Drazen [Department of Physics, Faculty of Science, University of Zagreb, P.O. Box 331, HR-10002 Zagreb (Croatia)

    2010-12-15

    As the vacuum state of a quantum field is not an eigenstate of the Hamiltonian density, the vacuum energy density can be represented as a random variable. We present an analytical calculation of the probability distribution of the vacuum energy density for real and complex massless scalar fields in Minkowski space. The obtained probability distributions are broad and the vacuum expectation value of the Hamiltonian density is not fully representative of the vacuum energy density.

  5. Synchronization Phenomena and Epoch Filter of Electroencephalogram

    NASA Astrophysics Data System (ADS)

    Matani, Ayumu

    Nonlinear electrophysiological synchronization phenomena in the brain, such as event-related (de)synchronization, long distance synchronization, and phase-reset, have received much attention in neuroscience over the last decade. These phenomena contain more electrical than physiological keywords and actually require electrical techniques to capture with electroencephalography (EEG). For instance, epoch filters, which have just recently been proposed, allow us to investigate such phenomena. Moreover, epoch filters are still developing and would hopefully generate a new paradigm in neuroscience from an electrical engineering viewpoint. Consequently, electrical engineers could be interested in EEG once again or from now on.

  6. Elevated temperature annealing of the neutron induced reverse current and corresponding defect levels in low and high resistivity silicon detectors

    SciTech Connect

    Eremin, V.; Ivanov, A.; Verbitskaya, E. [Academy of Sciences of Russia, St. Petersburg (Russian Federation). A.F. Ioffe Physico-Technical Institute] [Academy of Sciences of Russia, St. Petersburg (Russian Federation). A.F. Ioffe Physico-Technical Institute; Li, Z.; Kraner, H.W. [Brookhaven National Lab., Upton, NY (United States)] [Brookhaven National Lab., Upton, NY (United States)

    1995-08-01

    A new aspect of degradation phenomena of neutron irradiated silicon detectors has been revealed which consists in the significant influence of carbon related defect transformation on the detector reverse current (I{sub rev}). The annealing of the reverse current at elevated temperatures and the corresponding changes of the deep level transient spectroscopy (DLTS) spectra of defects for fast neutron irradiated silicon detectors, fabricated on high (4--6) k{Omega}-cm, moderate (0.5--1.0 k{Omega}-cm) and low (<100 {Omega}-cm) resistivity silicon material have been investigated. For all resistivity silicon detectors studied in this work, three annealing stages of the defects with deep levels in the energy band gap have been observed: (1) the transformation of carbon related defects in the temperature range of 20--72 C; (2) decrease of the peak E{sub c}{minus}0.4 eV at 150 C, and (3) complete annealing of the peak e{sub c}{minus}0.4 eV at 350 C. The transformations of carbon related defects consisted in the annealing of interstitial carbon (C{sub i}) and simultaneous generation of C{sub i}-O{sub i} complex and was accompanied by a significant reduction of the reverse current. The decrease of the peak E{sub c} {minus} 0.4 eV was observed in the temperature range of 72--350 C and was affected by both the annealing of the E-center (V-P complex) and single minus charge state of divacancy (VV) and by the changes in the filling of the deep levels in high or moderate resistivity Si. The results show the comparable role of the V-P complex and VV-center in formation of E{sub c} {minus} 0.4 eV defect in high and moderate resistivity silicon.

  7. Measurement of partial pressures in vacuum technology and vacuum physics

    NASA Technical Reports Server (NTRS)

    Huber, W. K.

    1986-01-01

    It is pointed out that the measurement of gaseous pressures of less than 0.0001 torr is based on the ionization of gas atoms and molecules due to collisions with electrons. The particle density is determined in place of the pressure. The ionization cross sections for molecules of various gases are discussed. It is found that the true pressure in a vacuum system cannot be determined with certainty if it is unknown which gas is present. Effects of partial pressure determination on the condition of the vacuum system are discussed together with ion sources, systems of separation, and ion detection.

  8. Optical Analysis Of The Vacuum Arc Plasma Generated In Cup-Shape Contacts

    SciTech Connect

    Pavelescu, G.; Gherendi, F. [National Institute for Optoelectronics, Bucharest-Magurele (Romania); Pavelescu, D. ['Politehnica' University of Bucharest, Bucharest (Romania); Dumitrescu, G.; Anghelita, P. [Electrotechnical Institute, ICPE, Bucharest (Romania)

    2007-04-23

    In this paper are presented the results of the optical analysis on the rotating arc plasma, generated in the vacuum low voltage circuit breaker with cup-shaped contacts. An adequate experimental setup was used for single shot time and spatial resolved spectroscopy in order to analyze the evolution of the vacuum arc plasma. Different current interruption situations are correlated with plasma spectral diagnosis. The study is aimed to contribute to a better understanding of the complex phenomena that take place in the interruption process of high currents that appears in the short-circuit regime of electrical networks.

  9. Bit patterned media optimization at 1 Tdot/in{sup 2} by post-annealing

    SciTech Connect

    Hellwig, Olav; Marinero, Ernesto E.; Kercher, Dan; Hennen, Tyler; McCallum, Andrew; Dobisz, Elizabeth; Wu, Tsai-Wei; Lille, Jeff; Hirano, Toshiki; Ruiz, Ricardo; Grobis, Michael K.; Weller, Dieter; Albrecht, Thomas R. [San Jose Research Center, HGST—A Western Digital Company, 3403 Yerba Buena Rd., San Jose, California 95135 (United States)

    2014-09-28

    We report on the fabrication of 1 Tdot/in{sup 2} bit patterned media with high coercivity (H{sub C}) and narrow intrinsic switching field distribution (iSFD) based on nanoimprint from a master pattern formed by e-beam guided block copolymer assembly onto a carbon hard mask and subsequent pattern transfer via etching into a thin CoCrPt perpendicular anisotropy recording layer. We demonstrate that an additional vacuum annealing step after pattern transfer into the CoCrPt layer and after Carbon hard mask removal not only yields recovery from undesired damage of the island edges, but actually transforms the islands into a magnetically more favorable compositional phase with higher H{sub C}, lower iSFD/H{sub C}, and three-fold increased thermal stability. Energy filtered transmission electron microscopy analysis reveals that the diffusion of Cr from the island cores to the periphery of the islands during post-annealing is responsible for the transformation of the magnetic bits into a more stable state.

  10. Growth and surface modification of LaFeO3 thin films induced by reductive annealing

    NASA Astrophysics Data System (ADS)

    Flynn, Brendan T.; Zhang, Kelvin H. L.; Shutthanandan, Vaithiyalingam; Varga, Tamas; Colby, Robert J.; Oleksak, Richard P.; Manandhar, Sandeep; Engelhard, Mark H.; Chambers, Scott A.; Henderson, Michael A.; Herman, Gregory S.; Thevuthasan, Suntharampillai

    2015-03-01

    The mixed electronic and ionic conductivity of perovskite oxides has enabled their use in diverse applications such as automotive exhaust catalysts, solid oxide fuel cell cathodes, and visible light photocatalysts. The redox chemistry at the surface of perovskite oxides is largely dependent on the oxidation state of the metal cations as well as the oxide surface stoichiometry. In this study, LaFeO3 (LFO) thin films grown on yttria-stabilized zirconia (YSZ) was characterized using both bulk and surface sensitive techniques. A combination of in situ reflection high-energy electron diffraction (RHEED), X-ray diffraction (XRD), and Rutherford backscattering spectrometry (RBS) demonstrated that the film is primarily textured in the [1 0 0] direction and is stoichiometric. High-resolution transmission electron microscopy measurements show regions that are dominated by [1 0 0] oriented LFO grains that are oriented with respect to the substrates lattice. However, selected regions of the film show multiple domains of grains that are not [1 0 0] oriented. The film was annealed in an ultra-high vacuum chamber to simulate reducing conditions and studied by angle-resolved X-ray photoelectron spectroscopy (XPS). Iron was found to exist as Fe(0), Fe(II), and Fe(III) depending on the annealing conditions and the depth within the film. A decrease in the concentration of surface oxygen species was correlated with iron reduction. These results should help guide and enhance the design of LFO materials for catalytic applications.

  11. Origin of exchange decoupling effects in high-coercivity air-annealed CoPd multilayers

    NASA Astrophysics Data System (ADS)

    Egelhoff, W. F.; McMichael, R. D.; Mallett, J. J.; Shapiro, A. J.; Powell, C. J.; Bonevich, J. E.; Judy, J. H.; Thomas, J. H.; Svedberg, E. B.

    2005-05-01

    We have achieved excellent exchange decoupling of grains in CoPd multilayers by annealing in air at 300°C. Samples exhibit a slope in the hysteresis loop close to 1.0, nucleation fields as large as 11kOe, and coercivities as large as 16kOe. These are among the best properties ever achieved for CoPd multilayers. In samples of the general type seed layer(0.3nmCo1nmPd)×15\\capping layer, it appears that atoms diffuse rapidly up and down the grain boundaries at 300°C. From x-ray photoelectron and Auger depth profiling, we have found that when Co atoms arrive at the surface they become oxidized and remain at the surface, leaving the grain boundaries depleted in Co and apparently nonmagnetic. If the annealing is carried out in vacuum, exchange decoupling of the grains does not occur. This result supports our conclusion that the presence of oxygen plays a crucial role. When Au or Pt atoms are present in the seed layer or capping layer, they diffuse into the CoPd grain boundaries and apparently enhance the exchange decoupling of grains.

  12. Improvement of magnetomechanical properties of cobalt ferrite by magnetic annealing

    Microsoft Academic Search

    C. C. H. Lo; A. P. Ring; J. E. Snyder; D. C. Jiles

    2005-01-01

    We report dramatic improvements in both magnetostriction level and strain derivative of polycrystalline cobalt ferrite as a result of magnetic annealing. Magnetostrictive cobalt ferrite composites have potential for use in advanced magnetomechanical stress and torque sensors due to their high sensitivity of magnetization to applied stresses and high levels of magnetostriction. Results show that annealing cobalt ferrite at 300°C in

  13. Behaviour of Neutron-irradiated Ammonium Sulphate on Thermal Annealing

    Microsoft Academic Search

    Nikola Getoff; Masaru Nishikawa

    1961-01-01

    THE behaviour of a neutron-irradiated substance in thermal annealing is known to depend on the temperature and on the period of heating. Normally, the retention reaches a saturation value after a few hours of heating. Very recently, experimental evidence was obtained which indicates that the ammonium group in a compound can influence the course of thermal and radiation annealing1. Potassium

  14. LIPS III-burst anneal solar array experiment

    Microsoft Academic Search

    M. Thompson; M. Morgan; W. E. Horne; S. Cannaday

    1989-01-01

    The burst anneal solar array, which is one of three solar power experiments developed space deployment on the US Naval Research Laboratory third Living Plume Shield (LIPS III) satellite, is discussed. Burst annealing involves rapidly cycling solar cells to an elevated temperature to completely recover cell damage caused by electron and proton radiation. The LIPS III experimental array consists of

  15. Applying simulated annealing to location-planning models

    Microsoft Academic Search

    Alan T. Murray; Richard L. Church

    1996-01-01

    Simulated annealing is a computational approach that simulates an annealing schedule used in producing glass and metals. Originally developed by Metropolis et al. in 1953, it has since been applied to a number of integer programming problems, including the p-median location-allocation problem. However, previously reported results by Golden and Skiscim in 1986 were less than encouraging. This article addresses the

  16. QISA: Incorporating quantum computation into Simulated Annealing for optimization problems

    Microsoft Academic Search

    Zhanghui Chen; Ping Luo

    2011-01-01

    This paper proposes a novel model of QISA (Quantum-Inspired Simulated Annealing) which embeds quan- tum computation into the Simulated Annealing (SA) process for optimization problems. Compared with previous SA studies, QISA adopts Quantum Bits (Qubits) rather than the conventional binary bits as the coding scheme, and update the entries in the Qubits sequence with different probabilities by the proposed methods

  17. Maintenance scheduling by using simulated annealing method [for power plants

    Microsoft Academic Search

    T. Satoh; K. Nara

    1991-01-01

    The thermal power plant generator maintenance scheduling problem is addressed. The problem is formulated as a mixed-integer programming problem, and it is solved by using an optimization method known as simulated annealing. Since the simulated annealing method assumes an analogy between a physical multiparticle system and a combinatorial optimization problem, a global minimum can be found with high probability through

  18. Toward Understanding Dynamic Annealing Processes in Irradiated Ceramics 

    E-print Network

    Myers, Michael

    2013-03-04

    of the evolution of defects after damage cascade thermalization, referred to as dynamic annealing, is quite limited. Unraveling the mechanisms associated with dynamic annealing is crucial since such processes play an important role in the formation of stable post-irradiation...

  19. Robust design of multimachine power system stabilizers using simulated annealing

    Microsoft Academic Search

    M. A. Abido

    2000-01-01

    Robust design of multimachine power system stabilizers (PSSs) using simulated annealing (SA) optimization technique is presented in this paper. The proposed approach employs SA to search for optimal parameter settings of a widely used conventional fixed-structure lead-lag PSS (CPSS). The parameters of the proposed simulated annealing based power system stabilizer (SAPSS) are optimized in order to shift the system electromechanical

  20. An Efficient Simulated Annealing Schedule: Implementation and Evaluation

    Microsoft Academic Search

    Jimmy Lam; Jean-Marc Delosme

    We present an implementation of an efficient general simulated annealing schedule and demonstrate experimentally that the new schedule achieves speedups often exceeding an order of magnitude when compared with other general schedules currently available in the literature. To assess the performance of simulated annealing as a general method for solving combinatorial optimization problems, we also compare the method with efficient

  1. Annealed high-density amorphous ice under pressure

    E-print Network

    Loss, Daniel

    ARTICLES Annealed high-density amorphous ice under pressure RICHARD J. NELMES1 *, JOHN S. LOVEDAY1 ices--LDA and HDA--as proxies for the supercooled liquids. But numerous studies over the past decade a previously uncharacterized state of high-density amorphous ice obtained if HDA is annealed at pressures near

  2. Chairman : B. ESCAIG M. LORETTO.-Tetrahedra annealing.

    E-print Network

    Paris-Sud XI, Université de

    DISCUSSION Chairman : B. ESCAIG M. LORETTO.-Tetrahedra annealing. J. WASHBURN.- Recent Experiments, e. g. stacking fault loops and or tetrahedra. Loretto reported on recent direct observations of the annealing of such tetrahedra in gold, usinghigh voltage electron microscopy (cf. Fraser et al., Phil. Mag

  3. Post irradiation annealing of uranium-molybdenum ternary alloys

    Microsoft Academic Search

    D. Kramer; W. V. Johnston

    1963-01-01

    The effects of post-irradiation annealing on density changes in U-- Mo ; alloys were investigated. Density changes that occurred in all the alloys ; studied during irradiation were accounted for by the solid fission products ; produced. No further density changes took place in the ternary systems studied ; (U- Mo-- Si and U-- Mo-- Sn) when annealed at 650

  4. ON CONSTRAINED ANNEALED BOUNDS FOR LINEAR CHAIN PINNING MODELS

    E-print Network

    an Hamiltonian that, for a system of size N, is a function HN, of the trajectory S, but depending only on S0, S1 GIACOMIN Abstract. The free energy of quenched disordered systems is bounded above by the free energy of the corresponding annealed system. This bound may be improved by ap- plying the annealing procedure, which is just

  5. TOP OF STRAND ANNEALING TOWER, ONE OF FIVE SUCH STRUCTURES ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    TOP OF STRAND ANNEALING TOWER, ONE OF FIVE SUCH STRUCTURES THE BUFFALO PLANT OF AMERICAN BRASS. HEAVIER-GAUGE STRIP IS CONTINUOUSLY ANNEALED TO GIVE THE PRODUCT A MORE UNIFORM GRAIN SIZE AND RENDER IT MORE DUCTILE. - American Brass Foundry, 70 Sayre Street, Buffalo, Erie County, NY

  6. Ambroise August Liébeault and psychic phenomena.

    PubMed

    Alvarado, Carlos S

    2009-10-01

    Some nineteenth-century hypnosis researchers did not limit their interest to the study of the conventional psychological and behavioral aspects of hypnosis, but also studied and wrote about psychic phenomena such as mental suggestion and clairvoyance. One example, and the topic of this paper, was French physician Ambroise August Liébeault (1823-1904), who influenced the Nancy school of hypnosis. Liébeault wrote about mental suggestion, clairvoyance, mediumship, and even so-called poltergeists. Some of his writings provide conventional explanations of the phenomena. Still of interest today, Liébeault's writings about psychic phenomena illustrate the overlap that existed during the nineteenth-century between hypnosis and psychic phenomena--an overlap related to the potentials of the mind and its subconscious activity. PMID:19862897

  7. Reproductive phenomena of a sexual buffelgrass plant

    E-print Network

    Taliaferro, Charles Millard

    1965-01-01

    lines apomictic lines. 21 22 REPRODUCTIVE PHENOMENA OF A SEXUAL BUFFELGRASS PLANT INTRODUCTION Buffelgrass, Pennisetum ciliare (L. ) Link, is a polymorphic, perennial, warm-season, bunch grass with a native range extending from Africa to India...

  8. Perspective: Emergent magnetic phenomena at interfaces

    NASA Astrophysics Data System (ADS)

    Suzuki, Yuri

    2015-06-01

    The discovery of emergent magnetic phenomena is of fundamental and technological interest. This perspective highlights recent promising examples of emergent ferromagnetism at complex oxide interfaces in the context of spin based electronics.

  9. Fractal Geometry and Spatial Phenomena A Bibliography

    E-print Network

    California at Santa Barbara, University of

    Fractal Geometry and Spatial Phenomena A Bibliography January 1991 Mark MacLennan, A. Stewart. MEASUREMENT ISSUES........................................................... 8 II.1 ESTIMATION OF FRACTAL DIMENSION - GENERAL ISSUES .......... 8 II.2 ESTIMATION OF FRACTAL DIMENSION FOR CURVES/PROFILES ... 9 II.3

  10. D-Zero Vacuum System

    SciTech Connect

    Wintercorn, S.J.; /Fermilab

    1986-04-07

    The system pumping speed was calculated by taking the reciprocal of the sum of the reciprocal pump speed and the reciprocal line conductances. The conductances of the pipe were calculated from the following formulas taken from the Varian vacuum manual. This report updates the original to reflect the pumping curves and basic vacuum system characteristics for the purchased components and installed piping of the D-Zero vacuum system. The system consists of two Edward's E2M275 two stage mechanical pumps, a Leybold-Heraeus WSU2000 Blower and three Varian 4' diffusion pumps (one for each cryostat). Individual pump and system pumping speed curves and a diagram of the system is included.

  11. Mathematical theory of physical vacuum

    NASA Astrophysics Data System (ADS)

    Magnitskii, N. A.

    2011-06-01

    This article sets out mathematical basics of unifying fundamental physical theory, with a single postulate of nonvoid physical vacuum. It will be shown that all basic equations of classical electrodynamics, quantum mechanics and gravitation theory could be derived from two nonlinear equations, which define dynamics of physical vacuum in three-dimensional Euclidean space and, in turn, are derived from equations of Newtonian mechanics. Through the characteristics of physical vacuum, namely its density and propagation velocity of various density's perturbations, such principal physical conceptions as matter and antimatter, electric, magnetic and gravitational fields, velocity of light, electron, photon and other elementary particles, internal energy, mass, charge, spin, quantum properties, Planck constant and fine structure constant will have clear and sane definitions.

  12. Impedances of Laminated Vacuum Chambers

    SciTech Connect

    Burov, A.; Lebedev, V.; /Fermilab

    2011-06-22

    First publications on impedance of laminated vacuum chambers are related to early 70s: those are of S. C. Snowdon [1] and of A. G. Ruggiero [2]; fifteen years later, a revision paper of R. Gluckstern appeared [3]. All the publications were presented as Fermilab preprints, and there is no surprise in that: the Fermilab Booster has its laminated magnets open to the beam. Being in a reasonable mutual agreement, these publications were all devoted to the longitudinal impedance of round vacuum chambers. The transverse impedance and the flat geometry case were addressed in more recent paper of K. Y. Ng [4]. The latest calculations of A. Macridin et al. [5] revealed some disagreement with Ref. [4]; this fact stimulated us to get our own results on that matter. Longitudinal and transverse impendances are derived for round and flat laminated vacuum chambers. Results of this paper agree with Ref. [5].

  13. Encapsulated Annealing: Enhancing the Plasmon Quality Factor in Lithographically–Defined Nanostructures

    PubMed Central

    Bosman, Michel; Zhang, Lei; Duan, Huigao; Tan, Shu Fen; Nijhuis, Christian A.; Qiu, Cheng–Wei; Yang, Joel K. W.

    2014-01-01

    Lithography provides the precision to pattern large arrays of metallic nanostructures with varying geometries, enabling systematic studies and discoveries of new phenomena in plasmonics. However, surface plasmon resonances experience more damping in lithographically–defined structures than in chemically–synthesized nanoparticles of comparable geometries. Grain boundaries, surface roughness, substrate effects, and adhesion layers have been reported as causes of plasmon damping, but it is difficult to isolate these effects. Using monochromated electron energy–loss spectroscopy (EELS) and numerical analysis, we demonstrate an experimental technique that allows the study of these effects individually, to significantly reduce the plasmon damping in lithographically–defined structures. We introduce a method of encapsulated annealing that preserves the shape of polycrystalline gold nanostructures, while their grain-boundary density is reduced. We demonstrate enhanced Q–factors in lithographically–defined nanostructures, with intrinsic damping that matches the theoretical Drude damping limit. PMID:24986023

  14. Encapsulated Annealing: Enhancing the Plasmon Quality Factor in Lithographically-Defined Nanostructures

    NASA Astrophysics Data System (ADS)

    Bosman, Michel; Zhang, Lei; Duan, Huigao; Tan, Shu Fen; Nijhuis, Christian A.; Qiu, Cheng–Wei; Yang, Joel K. W.

    2014-07-01

    Lithography provides the precision to pattern large arrays of metallic nanostructures with varying geometries, enabling systematic studies and discoveries of new phenomena in plasmonics. However, surface plasmon resonances experience more damping in lithographically-defined structures than in chemically-synthesized nanoparticles of comparable geometries. Grain boundaries, surface roughness, substrate effects, and adhesion layers have been reported as causes of plasmon damping, but it is difficult to isolate these effects. Using monochromated electron energy-loss spectroscopy (EELS) and numerical analysis, we demonstrate an experimental technique that allows the study of these effects individually, to significantly reduce the plasmon damping in lithographically-defined structures. We introduce a method of encapsulated annealing that preserves the shape of polycrystalline gold nanostructures, while their grain-boundary density is reduced. We demonstrate enhanced Q-factors in lithographically-defined nanostructures, with intrinsic damping that matches the theoretical Drude damping limit.

  15. Annealing effects on cathodoluminescence of zircon

    NASA Astrophysics Data System (ADS)

    Tsuchiya, Y.; Nishido, H.; Noumi, Y.

    2011-12-01

    U-Pb zircon dating (e. g., SHRIMP) is an important tool to interpret a history of the minerals at a micrometer-scale, where cathodoluminescence (CL) imaging allows us to recognize internal zones and domains with different chemical compositions and structural disorder at high spatial resolution. The CL of zircon is attributed by various types of emission centers, which are extrinsic ones such as REE impurities and intrinsic ones such as structural defects. Metamictization resulted from radiation damage to the lattice by alpha particles from the decay of U and Th mostly causes an effect on the CL features of zircon as a defect center. However, slightly radiation-damaged zircon, which is almost nondetectable by XRD, has not been characterized using CL method. In this study, annealing effects on CL of zircon has been investigated to clarify a recovery process of the damaged lattice at low radiation dose. A single crystal of zircon from Malawi was selected for CL measurements. It contains HfO2: 2.30 w.t %, U: 241 ppm and Th: 177 ppm. Two plate samples perpendicular to c and a axes were prepared for annealing experiments during 12 hours from room temperature to 1400 degree C. Color CL images were captured using a cold-cathode microscope (Luminoscope: Nuclide ELM-3R). CL spectral measurements were conducted using an SEM (JEOL: JSM-5410) combined with a grating monochromator (Oxford: Mono CL2) to measure CL spectra ranging from 300 to 800 nm in 1 nm steps with a temperature controlled stage. The dispersed CL was collected by a photoncounting method using a photomultiplier tube (Hamamatsu: R2228) and converted to digital data. All CL spectra were corrected for the total instrumental response. Spectral analysis reveals an anisotropy of the CL emission bands related to intrinsic defect center in blue region, radiation-induced defect center from 500 to 700 nm, and trivalent Dy impurity center at 480 and 580 nm, but their relative intensities are almost constant. CL on the surface perpendicular to c-axis, at which direction its intensity is maximum, was characterized in this study. Color CL imaging indicates yellow emission below 300 degree C, white to pale blue between 400 ~ 800 degree C and blue above 900 degree C. The broad band emission assigned to radiation-induced defect center in metamict state decreases in an increase of annealed temperature and disappeared above 700 degree C, whereas any change in XRD patterns was not detected. The blue CL emission caused by intrinsic defect center gradually increases in heating due to a recovery of its crystal field. Furthermore, the emission bands of trace amounts of trivalent Gd at 320 nm and Er at 400nm become to be appeared in response to a recrystallization by annealing. Therefore, CL analysis provides useful information on characteristics of the nature of metamict zircon rather than other conventional methods.

  16. Annealing a Magnetic Cactus into Phyllotaxis

    E-print Network

    Nisoli, Cristiano; Lammert, Paul E; Maynard, J D; Crespi, Vincent H

    2010-01-01

    The appearance of mathematical regularities in the disposition of leaves on a stem, scales on a pine-cone and spines on a cactus has puzzled scholars for millennia; similar so-called phyllotactic patterns are seen in self-organized growth, polypeptides, convection, magnetic flux lattices and ion beams. Levitov showed that a cylindrical lattice of repulsive particles can reproduce phyllotaxis under the (unproved) assumption that minimum of energy would be achieved by 2-D Bravais lattices. Here we provide experimental and numerical evidence that the Phyllotactic lattice is actually a ground state. When mechanically annealed, our experimental "magnetic cactus" precisely reproduces botanical phyllotaxis, along with domain boundaries (called transitions in Botany) between different phyllotactic patterns. We employ a structural genetic algorithm to explore the more general axially unconstrained case, which reveals multijugate (multiple spirals) as well as monojugate (single spiral) phyllotaxis.

  17. The endurance limit of JPCA alloy at 703 K in vacuum

    NASA Astrophysics Data System (ADS)

    Furuya, K.; Shiraishi, H.; Tanaka, M.

    1985-08-01

    The high-cycle fatigue behavior of the Japanese Primary Candidate Alloy (JPCA) was determined at 703 K in vacuum. Four different thermomechanical treatments produced the changes in dislocation structure and dispersion of Ti-rich MC type carbides. Applying load controlled sine waves of 30 Hz in tension-compression mode, ductile fractures with striations and dimples were observed for both solution annealed and subsequently aged alloys at 1073 K, while brittle facets and wavy patterns with tearing by shear were observed for 15% cold worked alloy. The fatigue life was shown to be improved by the cold work in the relatively high-stress and short-life regime. But the fatigue endurance limit at 10 7 cycles for cold worked JPCA was 550 MN/m 2, slightly lower than that for solution annealed JPCA, and was furthermore decreased by aging for the precipitation of MC type carbides.

  18. [Fabrication of annealing equipment for optically stimulated luminescence (OSL) dosimeter].

    PubMed

    Nakagawa, Kohei; Hayashi, Hiroaki; Okino, Hiroki; Takegami, Kazuki; Okazaki, Tohru; Kobayashi, Ikuo

    2014-10-01

    The optically stimulated luminescence (OSL) dosimeter is a useful detector for measuring absorbed doses of X-rays. A small-type OSL dosimeter, "nanoDot", has recently been developed by Landauer, Inc., who also manufacture "microStar" reading equipment. However, additional annealing equipment is needed if the nanoDot OSL dosimeter is used repeatedly. The aim of this study was to fabricate suitable annealing equipment using commonly available products. Our device positions four fluorescent light tubes in a close configuration. The heat from the fluorescent light tubes is dissipated using fans. Experiments using diagnostic X-ray equipment were carried out to evaluate the capability of our annealing equipment. The results indicated that our equipment can fully anneal the nanoDot OSL dosimeter with annealing times of approximately 20 hours. PMID:25327423

  19. High pressure annealing of Europium implanted GaN

    NASA Astrophysics Data System (ADS)

    Lorenz, K.; Miranda, S. M. C.; Alves, E.; Roqan, I. S.; O'Donnell, K. P.; Bo?kowski, M.

    2012-03-01

    GaN epilayers were implanted with Eu to fluences of 1×1013 Eu/cm2 and 1×1015 Eu/cm2. Post-implant thermal annealing was performed in ultra-high nitrogen pressures at temperatures up to 1450 ºC. For the lower fluence effective structural recovery of the crystal was observed for annealing at 1000 ºC while optical activation could be further improved at higher annealing temperatures. The higher fluence samples also reveal good optical activation; however, some residual implantation damage remains even for annealing at 1450 ºC which leads to a reduced incorporation of Eu on substitutional sites, a broadening of the Eu luminescence lines and to a strongly reduced fraction of optically active Eu ions. Possibilities for further optimization of implantation and annealing conditions are discussed.

  20. Thermal annealing of GaAs concentrator solar cells

    NASA Technical Reports Server (NTRS)

    Curtis, H. B.; Brinker, David J.

    1991-01-01

    Isochronal and isothermal annealing tests were performed on GaAs concentrator cells which were irradiated with electrons of various energies to fluences up to 1 x 10(exp 16) e/sq cm. The results include: (1) For cells irradiated with electrons from 0.7 to 2.3 MeV, recovery decreases with increasing electron energy. (2) As determined by the un-annealed fractions, isothermal and isochronal annealing produce the same recovery. Also, cells irradiated to 3 x 10(exp 15) or 1 x 10(exp 16) e/sq cm recover to similar un-annealed fractions. (3) Some significant annealing is being seen at 150 C although very long times are required.

  1. Annealed Importance Sampling Reversible Jump MCMC algorithms

    SciTech Connect

    Karagiannis, Georgios; Andrieu, Christophe

    2013-03-20

    It will soon be 20 years since reversible jump Markov chain Monte Carlo (RJ-MCMC) algorithms have been proposed. They have significantly extended the scope of Markov chain Monte Carlo simulation methods, offering the promise to be able to routinely tackle transdimensional sampling problems, as encountered in Bayesian model selection problems for example, in a principled and flexible fashion. Their practical efficient implementation, however, still remains a challenge. A particular difficulty encountered in practice is in the choice of the dimension matching variables (both their nature and their distribution) and the reversible transformations which allow one to define the one-to-one mappings underpinning the design of these algorithms. Indeed, even seemingly sensible choices can lead to algorithms with very poor performance. The focus of this paper is the development and performance evaluation of a method, annealed importance sampling RJ-MCMC (aisRJ), which addresses this problem by mitigating the sensitivity of RJ-MCMC algorithms to the aforementioned poor design. As we shall see the algorithm can be understood as being an “exact approximation” of an idealized MCMC algorithm that would sample from the model probabilities directly in a model selection set-up. Such an idealized algorithm may have good theoretical convergence properties, but typically cannot be implemented, and our algorithms can approximate the performance of such idealized algorithms to an arbitrary degree while not introducing any bias for any degree of approximation. Our approach combines the dimension matching ideas of RJ-MCMC with annealed importance sampling and its Markov chain Monte Carlo implementation. We illustrate the performance of the algorithm with numerical simulations which indicate that, although the approach may at first appear computationally involved, it is in fact competitive.

  2. QED vacuum loops and Inflation

    E-print Network

    H. M. Fried; Y. Gabellini

    2014-11-19

    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.

  3. Vacuum Plasma Spraying Replaces Electrodeposition

    NASA Technical Reports Server (NTRS)

    Holmes, Richard R.; Power, Chris; Burns, David H.; Daniel, Ron; Mckechnie, Timothy N.

    1992-01-01

    Vacuum plasma spraying used to fabricate large parts with complicated contours and inner structures, without uninspectable welds. Reduces time, and expense of fabrication. Wall of combustion chamber built up inside of outer nickel-alloy jacket by plasma spraying. Particles of metal sprayed partially melted in plasma gun and thrown at supersonic speed toward deposition surface. Vacuum plasma-spray produces stronger bond between the grooves and covering layer completing channels and wall of combustion chamber. In tests, bond withstood pressure of 20 kpsi, three times allowable limit by old method.

  4. Partial SOP for Tube Anneal Furnace, EML: 9/04 Instructions for temp controller for Anneal furnace

    E-print Network

    Reif, Rafael

    Partial SOP for Tube Anneal Furnace, EML: 9/04 Instructions for temp controller for Anneal furnace at the Temp controller unit for the next couple of steps, press and hold the RUN button until both the RUN ARROW twice to display set point 8. Use UP/DOWN ARROW to set desired temp 9. Press AUTO/MANUAL until

  5. Experimental Studies of Light Emission Phenomena in Superconducting RF Cavitites

    SciTech Connect

    Anthony, P.L.; /SLAC; Delayen, J.R.; /Jefferson Lab; Fryberger, D.; /SLAC; Goree, W.S.; Mammosser, J.; /Jefferson Lab /SNS Project, Oak Ridge; Szalata, Z.M.; II, J.G.Weisend /SLAC

    2009-08-04

    Experimental studies of light emission phenomena in superconducting RF cavities, which we categorize under the general heading of cavity lights, are described. The cavity lights data, which were obtained using a small CCD video camera, were collected in a series of nine experimental runs ranging from {approx} 1/2 to {approx} 2 h in duration. The video data were recorded on a standard VHS tape. As the runs progressed, additional instrumentation was added. For the last three runs a LabVIEW controlled data acquisition system was included. These runs furnish evidence for several, possibly related, light emission phenomena. The most intriguing of these is what appear to be small luminous objects {le} 1.5 mm in size, freely moving about in the vacuum space, generally without wall contact, as verified by reflections of the tracks in the cavity walls. In addition, on a number of occasions, these objects were observed to bounce off of the cavity walls. The wall-bounce aspect of most of these events was clearly confirmed by pre-bounce and post-bounce reflections concurrent with the tracks. In one of the later runs, a mode of behavior was observed that was qualitatively different from anything observed in the earlier runs. Perhaps the most perplexing aspect of this new mode was the observation of as many as seven luminous objects arrayed in what might be described as a macromolecular formation, coherently moving about in the interior of the cavity for extended periods of time, evidently without any wall contact. It is suggested that these mobile luminous objects are without explanation within the realm of established physics. Some remarks about more exotic theoretical possibilities are made, and future plans are discussed.

  6. Effects of thermal annealing on the microstructure of sputtered Al{sub 2}O{sub 3} coatings

    SciTech Connect

    Edlmayr, V.; Harzer, T. P.; Hoffmann, R.; Kiener, D.; Scheu, C.; Mitterer, C. [Department of Physical Metallurgy and Materials Testing, University of Leoben, A-8700 Leoben (Austria); Department of Chemistry, Ludwig-Maximilians-University of Munich, D-81377 Munich (Germany); Department of Physical Metallurgy and Materials Testing, University of Leoben, A-8700 Leoben (Austria)

    2011-07-15

    The morphology and microstructure of Al{sub 2}O{sub 3} thin films deposited by pulsed direct current magnetron sputtering were studied in the as-grown state and after vacuum annealing at 1000 deg. C for 12 h using transmission electron microscopy. For the coating deposited under low ion bombardment conditions, the film consists of small {gamma}- and/or {delta}-Al{sub 2}O{sub 3} grains embedded in an amorphous matrix. The grain size at the region close to the interface to the substrate was much larger than that of the remaining layer. Growth of the {gamma}-Al{sub 2}O{sub 3} phase is promoted during annealing but no transformation to {alpha}-Al{sub 2}O{sub 3} was detected. For high-energetic growth conditions, clear evidence for {gamma}-Al{sub 2}O{sub 3} formation was found in the upper part of the coating with grain size much larger than for low-energetic growth, but the film was predominately amorphous at the interface region. Annealing resulted in the transformation of {gamma}-Al{sub 2}O{sub 3} to {alpha}-Al{sub 2}O{sub 3}, while the mainly amorphous part crystallized to {gamma}-Al{sub 2}O{sub 3}.

  7. Vacuum-injection-molding processing

    SciTech Connect

    Kramer, D.P.; Massey, R.T.

    1982-01-01

    An improved processing technique for the manufacture of glass or glass-ceramic headers has been developed. Vacuum-injection molding is a relatively easy processing technique that has been used successfully in the fabrication of several different advantages in certain applications over the present fabrication process which uses glass preforms.

  8. Recent advances in Vacuum Electronics

    Microsoft Academic Search

    Baruch Levush

    2008-01-01

    Vacuum Electronics (VE) technology has been and will continue to be the enabling technology for entire classes of high-power high-frequency amplifiers with the most demanding specifications for use in both military and commercial systems. Here in this paper, TWT design and its application has been described. Among the wide variety of applications requiring high power, communication, radar, EW, and broadcasting

  9. Fluctuation Noise in Vacuum Tubes

    Microsoft Academic Search

    G. L. Pearson

    1934-01-01

    The fluctuation noises originating in vacuum tubes are treated theoretically under the following headings: (1) thermal agitation in the internal plate resistance of the tube, (2) shot effect and flicker effect from space current in the presence of space charge, (3) shot effect from electrons produced by collision ionization and secondary emission, and (4) space charge fluctuations due to positive

  10. Vacuum coating of plastic optics

    Microsoft Academic Search

    Ulrike Schulz; Norbert Kaiser

    2006-01-01

    Vacuum technologies for the deposition of optical interference coatings on polymer substrates, based on long-term experience in glass coating, have been under development for about 20 years. A growing market for precision optical elements and consumer optics moulded from thermoplastic polymers requires antireflective properties and hard coatings. Owing to the manifold chemical and physical properties of optical polymers, special efforts

  11. Peoperties of vacuum brass coatings

    Microsoft Academic Search

    I. L. Roikh; L. K. Glukhova; E. V. Efimovich; S. R. Pustotina; N. A. Litovchenko; V. P. Kirichenko

    1975-01-01

    This communication deals with the structure, phase composition, and mechanical properties of coatings of the system Cu-Zn, deposited by simultaneous condensation of Cu and Zn in a vacuum of 1 ?9 10 -4 torr from various evaporants at deposition rates of 3 ~\\/min and 5 p\\/min, respectively. The thickness of the coatings investigated was less than 20 tt. Depending on

  12. Degassing procedure for ultrahigh vacuum

    NASA Technical Reports Server (NTRS)

    Moore, B. C.

    1979-01-01

    Calculations based on diffusion coefficients and degassing rates for stainless-steel vacuum chambers indicate that baking at lower temperatures for longer periods give lower ultimate pressures than rapid baking at high temperatures. Process could reduce pressures in chambers for particle accelerators, fusion reactors, material research, and other applications.

  13. DCI wiggler magnet vacuum system

    SciTech Connect

    Souchet, R.; Marx, J.P.

    1988-09-30

    With the end of the high energy experiments in DCI, developments could take place at LURE and a five pole wiggler magnet program was launched in 1983 to exclusively dedicate DCI as a synchrotron radiation source. Design and performance measurements of the wiggler magnet vacuum system at DCI is presented. (AIP)

  14. HIGH PRODUCTIVITY VACUUM BLASTING SYSTEM

    SciTech Connect

    Dr. M.A. Ebadian

    2000-01-13

    The purpose of the project is to increase the productivity and economics of existing vacuum blasting technology. This technology is used to remove radioactive contamination, PCB's and lead-base paint and provides worker and environmental protection by continuously recycling the blast media and the full containment of the dust generated in the process.

  15. Plates for vacuum thermal fusion

    DOEpatents

    Davidson, James C. (Livermore, CA); Balch, Joseph W. (Livermore, CA)

    2002-01-01

    A process for effectively bonding arbitrary size or shape substrates. The process incorporates vacuum pull down techniques to ensure uniform surface contact during the bonding process. The essence of the process for bonding substrates, such as glass, plastic, or alloys, etc., which have a moderate melting point with a gradual softening point curve, involves the application of an active vacuum source to evacuate interstices between the substrates while at the same time providing a positive force to hold the parts to be bonded in contact. This enables increasing the temperature of the bonding process to ensure that the softening point has been reached and small void areas are filled and come in contact with the opposing substrate. The process is most effective where at least one of the two plates or substrates contain channels or grooves that can be used to apply vacuum between the plates or substrates during the thermal bonding cycle. Also, it is beneficial to provide a vacuum groove or channel near the perimeter of the plates or substrates to ensure bonding of the perimeter of the plates or substrates and reduce the unbonded regions inside the interior region of the plates or substrates.

  16. A vacuum ultraviolet spectrophotometric system

    NASA Technical Reports Server (NTRS)

    Spann, James F.; Keffer, Charles E.; Zukic, Muamer

    1993-01-01

    The development of a vacuum ultraviolet spectrophotometric system for measuring transmittance and reflectance at variable angles is presented. Using various detectors and sources, the spectrophotometric system has been used for wavelengths from 80 nm to 300 nm with optical components up to 80 mm in diameter. The capability exists to make measurements through the visible range.

  17. Vacuum barrier for excimer lasers

    DOEpatents

    Shurter, R.P.

    1992-09-15

    A barrier for separating the vacuum area of a diode from the pressurized gas area of an excimer laser. The barrier is a composite material comprising layers of a metal such as copper, along with layers of polyimide, and a matrix of graphite fiber yarns impregnated with epoxy. The barrier is stronger than conventional foil barriers, and allows greater electron throughput. 3 figs.

  18. Vacuum Flushing of Sewer Solids

    EPA Science Inventory

    The vacuum sewer and tank cleaning (flushing) technology removes sewer solids from urban drainage systems, such as storage tanks and pipes. This technology is both effective and inexpensive. In addition, it can be considered a true green technology. It operates under atmospheri...

  19. Vacuum barrier for excimer lasers

    DOEpatents

    Shurter, Roger P. (Jemez Springs, NM)

    1992-01-01

    A barrier for separating the vacuum area of a diode from the pressurized gas area of an excimer laser. The barrier is a composite material comprising layers of a metal such as copper, along with layers of polyimide, and a matrix of graphite fiber yarns impregnated with epoxy. The barrier is stronger than conventional foil barriers, and allows greater electron throughput.

  20. VACUUM SYSTEMS PHYSICS 359E

    E-print Network

    Landstreet, John D.

    experiments in high vacuum is to permit atoms or ions to move with- out colliding with air molecules. The mean at room temperature corresponds to a particle density of 3.5 × 1016 particles cm-3. Pressures in the range, metal gaskets, and a selection of ion pumps, cryopumps, molecular turbopumps, and titanium sublimation

  1. HIGH PRODUCTIVITY VACUUM BLASTING SYSTEM

    SciTech Connect

    William S. McPhee

    1999-05-31

    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 construct a pre-prototype of the nozzle, blast head with wind curtain, sensors, and dust separator and test this system to assess the performance of the new design under controlled conditions at the contractor's facility. In phase III, the Contractor shall design and construct a prototype of the High Productivity Vacuum Blasting System, based on the results of the pre-prototype design and testing performed. This unit will be a full-scale prototype and will be tested at a designated Department of Energy (DOE) facility. Based on the results, the system performance, the productivity, and the economy of the improved vacuum blasting system will be evaluated.

  2. Regulating vacuum pump speed with feedback control

    SciTech Connect

    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{sup 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.

  3. Can zero-point phenomena truly be the origin of inertia?

    E-print Network

    C. T. Ridgely

    2001-09-16

    A current approach to the problem of inertia suggests that the origin of the inertial properties of matter is the interaction between matter and vacuum electromagnetic zero-point radiation. Herein, it is shown that zero-point phenomena can be treated as the origin of inertia only when one chooses to ignore the mass-energy content of matter. In the absence of any physical basis for such a choice, it is concluded that zero-point-induced forces must arise in addition to the intrinsic inertial properties of ordinary matter.

  4. A Class of Stationary Electromagnetic Vacuum Fields

    E-print Network

    Israel, Werner; Wilson, Gordon A.

    1972-01-10

    It is shown how a new class of stationary electromagnetic vacuum fields can be generated from solutions of Laplace's equation. These fields are a stationary generalization of the static electromagnetic vacuum fields of Weyl, Majumdar, and Papapetrou...

  5. Crystal growth and annealing for minimized residual stress

    DOEpatents

    Gianoulakis, Steven E. (Albuquerque, NM)

    2002-01-01

    A method and apparatus for producing crystals that minimizes birefringence even at large crystal sizes, and is suitable for production of CaF.sub.2 crystals. The method of the present invention comprises annealing a crystal by maintaining a minimal temperature gradient in the crystal while slowly reducing the bulk temperature of the crystal. An apparatus according to the present invention includes a thermal control system added to a crystal growth and annealing apparatus, wherein the thermal control system allows a temperature gradient during crystal growth but minimizes the temperature gradient during crystal annealing.

  6. Switching Circuit for Shop Vacuum System

    NASA Technical Reports Server (NTRS)

    Burley, R. K.

    1987-01-01

    No internal connections to machine tools required. Switching circuit controls vacuum system draws debris from grinders and sanders in machine shop. Circuit automatically turns on vacuum system whenever at least one sander or grinder operating. Debris safely removed, even when operator neglects to turn on vacuum system manually. Pickup coils sense alternating magnetic fields just outside operating machines. Signal from any coil or combination of coils causes vacuum system to be turned on.

  7. The making of extraordinary psychological phenomena.

    PubMed

    Lamont, Peter

    2012-01-01

    This article considers the extraordinary phenomena that have been central to unorthodox areas of psychological knowledge. It shows how even the agreed facts relating to mesmerism, spiritualism, psychical research, and parapsychology have been framed as evidence both for and against the reality of the phenomena. It argues that these disputes can be seen as a means through which beliefs have been formulated and maintained in the face of potentially challenging evidence. It also shows how these disputes appealed to different forms of expertise, and that both sides appealed to belief in various ways as part of the ongoing dispute about both the facts and expertise. Finally, it shows how, when a formal Psychology of paranormal belief emerged in the twentieth century, it took two different forms, each reflecting one side of the ongoing dispute about the reality of the phenomena. PMID:25363382

  8. Annealing-Environment Effects on the Properties of CoPt Nanoparticles Formed in Single-Crystal Al2O3 by Ion Implantation

    SciTech Connect

    White, Clark W [ORNL; Withrow, Stephen P [ORNL; Budai, John D [ORNL; Thomas, Darrell Keith [ORNL; Williams, J. M. [BronteK Delta Corporation; Meldrum, A. [University of Alberta, Edmondton, Canada; Sorge, K. D. [University of Nebraska, Lincoln; Thompson, James R [ORNL; Ownby, Gary Webb [ORNL; Wendelken, J F [ORNL; Boatner, Lynn A [ORNL

    2005-01-01

    The ion implantation of nearly equal doses of Co and Pt into a single-crystal Al{sub 2}O{sub 3} host followed by thermal annealing leads to the formation of nanoparticles whose phase, structure, and physical properties are strongly dependent on the annealing environment. Annealing in 96%Ar+4%H{sub 2} gives rise to ferromagnetic, chemically ordered CoPt nanoparticles with the L1{sub 0} structure and a magnetic coercivity that can exceed 10 kOe at 5 K. Annealing in O{sub 2} (or in Ar) does not result in the formation of a CoPt alloy. Instead, the implanted Pt precipitates to form oriented elemental Pt nanoparticles, and the implanted Co combines with oxygen to form Co{sub 3}O{sub 4} oxide nanoparticles. Annealing in ultrahigh-vacuum conditions results in a mixture of phases including CoPt{sub 3} and Co{sub 3}O{sub 4} and possibly Co. The results obtained for Co+Pt-implanted Al{sub 2}O{sub 3} are compared with the previous results for Fe+Pt-implanted Al{sub 2}O{sub 3} annealed in similar environments.

  9. High-temperature annealing characteristics of tungsten and tungsten nitride Schottky contacts to GaAs under different annealing conditions

    NASA Astrophysics Data System (ADS)

    Yu, Kin Man; Jaklevic, J. M.; Haller, E. E.; Cheung, S. K.; Kwok, P. S.

    1988-08-01

    We have systematically investigated the structural and electrical characteristics of thin-film tungsten and reactively sputtered tungsten nitride (WNx) Schottky contacts to GaAs under high-temperature annealing conditions (with annealing temperatures ranging from 700 to 850 °C) in an arsenic-overpressure and flowing nitrogen ambient with and without a silicon dioxide capping layer. Compositions of the WNx films measured by Rutherford backscattering spectrometry and proton resonant scattering techniques indicate a linear relationship between x and the nitrogen partial pressure during sputtering. Glancing angle x-ray diffraction studies revealed that for nonzero nitrogen partial pressure, the as-deposited films were amorphous, and after annealing these films converted to polycrystalline W2 N and W phases. A surface layer of W2 As3 phase was also observed after As-overpressure capless annealing and was believed to be the result of reactions between W and the ambient As gas. Electrical measurements showed that all WNx /GaAs contacts (with x=0-0.5) were thermally stable up to an annealing temperature of 850 °C. A diode edge effect is observed for WNx /GaAs diodes cap annealed in As overpressure at temperatures higher than 800 °C. The maximum achievable Schottky barrier heights for these contacts were found to be independent of the nitrogen content in the films but are influenced by the annealing conditions. We also explored the role played by nitrogen on the thermal stability and barrier height of the contacts.

  10. Ion pump provides increased vacuum pumping speed

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Multiple-cell ion pumps with increased vacuum pumping speed are used for producing ultrahigh vacuums in vacuum tubes and mass spectrometers. The pump has eight cathode-anode magnetron cells arranged in a cylinder which increase the surface area of the cathode.

  11. The APS beamline front end vacuum system

    Microsoft Academic Search

    Nielsen

    1993-01-01

    This report discusses the design of the vacuum system for the advanced photon source beamline front ends. Included in this report are discussions on: vacuum calculations, the differential pump; front end vacuum set points; cleaning methods and agents; and continuing and completed research and development.

  12. RHIC vacuum instrumentation and control system

    Microsoft Academic Search

    R. C. Lee; D. Pate; L. A. Smart; D. Weiss; D. Zigrosser

    1999-01-01

    The Relativistic Heavy Ion Collider (RHIC) Project is a nuclear physics research accelerator at Brookhaven National Laboratory (BNL) with beam circulation scheduled for May 1999. To achieve the necessary beam lifetime, the vacuum in the two concentric rings must be constantly monitored to isolate problem vacuum regions. One function of the RHIC vacuum instrumentation and control (I&C) system is to

  13. In Situ Monitoring of Vacuum Carburizing

    Microsoft Academic Search

    M. Bruncko; A. C. Kneissl; I. Anzel

    2009-01-01

    The present article describes development and testing of a new measurement method that enables nondestructive and in situ monitoring of a vacuum carburizing process. The principle of the method is based on monitoring the carbon diffusion during vacuum carburizing by the in-situ measurement of electrical resistance changes in the carburizing sample. Using this method the electrical resistance changes during vacuum

  14. Rotary bayonets for cryogenic and vacuum service

    Microsoft Academic Search

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

    1993-01-01

    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

  15. Fundamental investigation of duct/ESP phenomena

    SciTech Connect

    Brown, C.A. (Radian Corp., Austin, TX (United States)); Durham, M.D. (ADA Technologies, Inc., Englewood, CO (United States)); Sowa, W.A. (California Univ., Irvine, CA (United States). Combustion Lab.); Himes, R.M. (Fossil Energy Research Corp., Laguna Hills, CA (United States)); Mahaffey, W.A. (CHAM of North America, Inc., Huntsville, AL (United States))

    1991-10-21

    Radian Corporation was contracted to investigate duct injection and ESP phenomena in a 1.7 MW pilot plant constructed for this test program. This study was an attempt to resolve problems found in previous studies and answer remaining questions for the technology using an approach which concentrates on the fundamental mechanisms of the process. The goal of the study was to obtain a better understanding of the basic physical and chemical phenomena that control: (1) the desulfurization of flue gas by calcium-based reagent, and (2) the coupling of an existing ESP particulate collection device to the duct injection process. Process economics are being studied by others. (VC)

  16. Modeling of fundamental phenomena in welds

    SciTech Connect

    Zacharia, T.; Vitek, J.M. [Oak Ridge National Lab., TN (United States); Goldak, J.A. [Carleton Univ., Ottawa, Ontario (Canada); DebRoy, T.A. [Pennsylvania State Univ., University Park, PA (United States); Rappaz, M. [Ecole Polytechnique Federale de Lausanne (Switzerland); Bhadeshia, H.K.D.H. [Cambridge Univ. (United Kingdom)

    1993-12-31

    Recent advances in the mathematical modeling of fundamental phenomena in welds are summarized. State-of-the-art mathematical models, advances in computational techniques, emerging high-performance computers, and experimental validation techniques have provided significant insight into the fundamental factors that control the development of the weldment. The current status and scientific issues in the areas of heat and fluid flow in welds, heat source metal interaction, solidification microstructure, and phase transformations are assessed. Future research areas of major importance for understanding the fundamental phenomena in weld behavior are identified.

  17. Mirror fusion vacuum technology developments

    SciTech Connect

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

    1983-11-21

    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/sup 7/ to 10/sup 8/ l/s for D/sub 2/, T/sub 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.

  18. HIGH PRODUCTIVITY VACUUM BLASTING SYSTEM

    SciTech Connect

    William S. McPhee

    2001-08-31

    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.

  19. Radiation Reaction in Quantum Vacuum

    E-print Network

    Keita Seto

    2014-11-02

    From the development of the electron theory by H. A. Lorentz in 1906, many authors have tried to reformulate this model named "radiation reaction". P. A. M. Dirac derived the relativistic-classical electron model in 1938, which is now called the Lorentz-Abraham-Dirac model. But this model has the big difficulty of the run-away solution. Recently, this equation has become important for ultra-intense laser-electron (plasma) interactions. Therefore, it is desirable to stabilize this model of the radiation reaction for estimations. Via my recent research, I found a stabilized model of radiation reaction in quantum vacuum. This leads us to an updated Fletcher-Millikan's charge to mass ratio including radiation, de/dm, derived as the 4th order tensor measure. In this paper, I will discuss the latest update of the model and the ability of the equation of motion with radiation reaction in quantum vacuum via photon-photon scatterings.

  20. Radiation reaction in quantum vacuum

    NASA Astrophysics Data System (ADS)

    Seto, Keita

    2015-02-01

    Since the development of the radiating electron theory by P. A. M. Dirac in 1938 [P. A. M. Dirac, Proc. R. Soc. Lond. A 167, 148 (1938)], many authors have tried to reformulate this model, called the "radiation reaction". Recently, this equation has become important for ultra-intense laser-electron (plasma) interactions. In our recent research, we found a stabilized model of the radiation reaction in quantum vacuum [K. Seto et al., Prog. Theor. Exp. Phys. 2014, 043A01 (2014)]. It led us to an updated Fletcher-Millikan charge-to-mass ratio including radiation. In this paper, I will discuss the generalization of our previous model and the new equation of motion with the radiation reaction in quantum vacuum via photon-photon scatterings and also introduce the new tensor d{E}^{? ? ? ? }/dm, as the anisotropy of the charge-to-mass ratio.

  1. Data Visualization by Multidimensional Scaling: A Deterministic Annealing Approach

    E-print Network

    Clausen, Michael

    Data Visualization by Multidimensional Scaling: A Deterministic Annealing Approach Hansj¨org Klock to the multidimensional scaling concept (see also [3]). 1 #12; 2 Klock & Buhmann: Data Visualization by Multidimensional

  2. Annealing behavior of cadmium ion implanted GaSb

    NASA Astrophysics Data System (ADS)

    Pandey, S. D.; Dubey, S. K.

    2013-02-01

    Single crystal, n-type GaSb substrates implanted with 300 keV cadmium ions at fluence 1×1016cm-2 have been investigated for their annealing behavior. The defect density in the implanted sample was estimated as 1.4×1018cm-3 indicating that cadmium ion implantation produces many defects in GaSb. FTIR studies before and after rapid thermal annealing showed recrystalization and reduction in defect levels. Reflection spectra showed oscillatory interference fringes for as-implanted sample which vanished with gradual rapid thermal annealing. The broadening of peak and reduction in its intensity observed in XRD spectra of as-implanted sample disappeared with progressive annealing.

  3. Structural changes during annealing of GaInAsN

    SciTech Connect

    Kurtz, Sarah; Webb, J.; Gedvilas, L.; Friedman, D.; Geisz, J.; Olson, J.; King, R.; Joslin, D.; Karam, N.

    2001-02-05

    The alloy GaInAsN has great potential as a lower-band-gap material lattice matched to GaAs, but there is little understanding of what causes its poor optoelectronic properties and why these improve with annealing. This study provides information about the structural changes that occur when GaInAsN is annealed. The Fourier transform infrared spectra exhibit two primary features: a triplet at {approx}470 cm-1 (Ga--N stretch) and two or three bands at {approx}3100 cm-1 (N--H stretch). The change in the Ga--N stretch absorption can be explained if the nitrogen environment is converted from NGa{sub 4} to NInGa{sub 3} after annealing. The N--H stretch is also changed after annealing, implying a second, and unrelated, structural change.

  4. Annealing effect in raman scattering of various types of tourmalines

    NASA Astrophysics Data System (ADS)

    Hoang, Luc Huy; Hien, Nguyen Thi Minh; Chen, Xiang-Bai; Yang, In Sang

    2013-01-01

    Raman scattering studies of the annealing effect in spectra of seven natural tourmalines are presented. It was found that tourmalines containing Fe ions when annealed in air showed Raman features significantly different from those of the Fe-free minerals. Furthermore, tourmalines containing the Fe ions behaved differently depending on whether they were annealed in air or in argon. Our analysis indicated that these differences were mainly due to the Fe2+ ions present in the tourmalines. When Fe2+-tourmalines were annealed in air, the Fe2+ ions were oxidized into Fe3+ ions, and the oxidation strongly modified the crystal structure, even in tourmalines with a very low Fe2+ concentration (0.20 wt.%). Our finding may be helpful in studying the oxidation of other minerals which contain the Fe2+ ions.

  5. Design and fabrication of a tin-sulfide annealing furnace

    E-print Network

    Lewis, Raymond (Raymond A.)

    2011-01-01

    A furnace was designed and its heat transfer properties were analyzed for use in annealing thin-film tins-ulfide solar cells. Tin sulfide has been explored as an earth abundant solar cell material, and the furnace was ...

  6. Fabrication of Annealed Proton-Exchanged Waveguides for Vertical Integration 

    E-print Network

    Webb, Jacob Douglas

    2011-08-08

    There is a drive for improving the surface uniformity of optical waveguide devices in the photonics lab. This report focuses on the exploration of annealed proton exchange (APE) waveguide fabrication on lithium niobate crystal as a method...

  7. Distinguishing graphs with a quantum annealer using susceptibility measurements

    NASA Astrophysics Data System (ADS)

    Wittmann, Matthew; Hen, Itay; Young, A. P.

    2014-03-01

    Recently it has been proposed that the Graph Isomorphism (GI) problem could be solved using a quantum annealer. This is done by encoding the graphs into Ising Hamiltonians, identifying the vertices with spins and the edges with antiferromagnetic interactions. The idea is that measurements of simple observables during and at the end of the annealing process should distinguish non-isomorphic graphs. The first experimental study of the GI problem using D-Wave's quantum computer has been carried out by Vinci et al., utilizing measurements taken at the end of the annealing process. Here, we will present preliminary evidence that measurements taken part way through the annealing process, now obtainable using state-of-the-art devices, may offer better distinguishing capabilities.

  8. OBJECT KINETIC MONTE CARLO SIMULATIONS OF CASCADE ANNEALING IN TUNGSTEN

    SciTech Connect

    Nandipati, Giridhar; Setyawan, Wahyu; Heinisch, Howard L.; Roche, Kenneth J.; Kurtz, Richard J.; Wirth, Brian D.

    2014-03-31

    The objective of this work is to study the annealing of primary cascade damage created by primary knock-on atoms (PKAs) of various energies, at various temperatures in bulk tungsten using the object kinetic Monte Carlo (OKMC) method.

  9. Annealing effects on 5 nm iron oxide nanoparticles.

    PubMed

    Vargas, J M; Lima, E; Socolovsky, L M; Knobel, M; Zanchet, D; Zysler, R D

    2007-09-01

    Morphological, structural and magnetic properties of 4.8 nm iron oxide nanoparticles have been investigated after annealing under inert atmosphere at different temperatures. The as-prepared iron oxide nanoparticles have been synthesized by chemical route from high temperature reaction of Fe(acac)3 solution in presence of oleic acid and oleylamine surfactant. Annealing the particles at low temperatures (Tann = 573 K) produces an increment of the mean size from 4.8 nm to 6.0 nm, preserving the same morphology. The coercive field of the annealed sample has a small increasing with respect to the as-prepared sample in agreement with the mean particle volume change. Annealing at higher temperature (Tann = 823 K) leads to a bimodal size distribution of the iron oxide nanoparticles with 6.0 nm and 17 nm mean sizes respectively, where the bigger particles dominate the observed magnetic properties. PMID:18019166

  10. Inflation in a Symmetric Vacuum

    E-print Network

    Kevin Cahill

    2007-05-23

    If in a finite universe, the tree-level vacuum is a symmetric superposition of coherent states, in each of which the inflaton field assumes a different, energy-minimizing mean value (vev), then the resulting energy is positive and decreases exponentially as the volume of the universe increases. This effect can drive inflation when that volume is small and explain part of dark energy when it is big, but the effect is exceedingly tiny except at very early times.

  11. Vacuum Ultraviolet Photochemistry of Cyclobutanone

    Microsoft Academic Search

    Alfred A. Scala; Daniel G. Ballan

    1972-01-01

    The photodecomposition of cyclobutanone in the vacuum ultraviolet is characterized by ? C2H4 + CH2 + CO,? CO+C3H6. At 147.0 nm and high pressure the quantum yields of Reactions (1) and (2) are approximately 0.7 and 0.25 respectively. At 123.6 and 106.7–4.8 nm the ratio of the quantum yield of Reaction (2) relative to Reaction (1) is 0.28. The quantum

  12. Accurate vacuum-polarization calculations

    Microsoft Academic Search

    Hans Persson; Ingvar Lindgren; Sten Salomonson; Per Sunnergren

    1993-01-01

    A numerical scheme for evaluating the part of the one-photon vacuum-polarization effect not accounted for by the Uehling potential (the Wichmann-Kroll effect) is presented. The method can be used with an arbitary atomic model potential describing the bound electrons. Benchmark results for this effect are presented for hydrogenlike levels using a uniform nuclear-charge distribution. The effect of direct and exchange

  13. The Statistics of Vacuum Geometry

    E-print Network

    Melissa Duncan; Wei Gu; Yang-Hui He; Da Zhou

    2014-06-22

    We investigate the vacuum moduli space of supersymmetric gauge theories en masse by probing the space of such vacua from a statistical standpoint. Using quiver gauge theories with ${\\cal N}=1$ supersymmetry as a testing ground, we sample over a large number of vacua as algebraic varieties, computing explicitly their dimension, degree and Hilbert series. We study the distribution of these geometrical quantities, and also address the question of how likely it is for the moduli space to be Calabi-Yau.

  14. Cold cathode vacuum discharge tube

    DOEpatents

    Boettcher, Gordon E. (Albuquerque, NM)

    1998-01-01

    A cold cathode vacuum discharge tube, and method for making same, with an interior surface of the trigger probe coated with carbon deposited by carbon vapor deposition (CVD) or diamond-like carbon (DLC) deposition. Preferably a solid graphite insert is employed in the probe-cathode structure in place of an aluminum bushing employed in the prior art. The CVD or DLC probe face is laser scribed to allow resistance trimming to match available trigger voltage signals and to reduce electrical aging.

  15. Vacuum Systems CTI-Cryogenics

    E-print Network

    Gellman, Andrew J.

    compressor supports all pumps up to eight inches in size and is designed for flexibility, allowing you with all Four-inch, Six-inch and Eight-inch On-Board or Cryo-Torr Cryopumps and On-Board Waterpumps Three-Board® Vacuum Systems Dimensions 16.65" h x 19.50"w x 19.59"d (423mm h x 495.3mm w x 498mm d) Weight 140 lbs

  16. Improved Vacuum-Tight Connector

    NASA Technical Reports Server (NTRS)

    Rudin, Frank

    1989-01-01

    Simple reinforcing tube increases service life and improves seal. Short stainless-steel tube inserted in copper tube to reinforce against compression, preventing leaks due to thermal distortion or to collapse under squeeze of ferrule in compressure fitting. Several test specimens of improved connector constructed, tested, and evaluated. Fittings not only operated successfully at required operating conditions of vacuum and temperature but also consistently demonstrated high reliability after loosened and tightened many times.

  17. Vacuum Stability of Standard Model^{++}

    E-print Network

    Luis A. Anchordoqui; Ignatios Antoniadis; Haim Goldberg; Xing Huang; Dieter Lust; Tomasz R. Taylor; Brian Vlcek

    2013-01-23

    The latest results of the ATLAS and CMS experiments point to a preferred narrow Higgs mass range (m_h \\simeq 124 - 126 GeV) in which the effective potential of the Standard Model (SM) develops a vacuum instability at a scale 10^{9} -10^{11} GeV, with the precise scale depending on the precise value of the top quark mass and the strong coupling constant. Motivated by this experimental situation, we present here a detailed investigation about the stability of the SM^{++} vacuum, which is characterized by a simple extension of the SM obtained by adding to the scalar sector a complex SU(2) singlet that has the quantum numbers of the right-handed neutrino, H", and to the gauge sector an U(1) that is broken by the vacuum expectation value of H". We derive the complete set of renormalization group equations at one loop. We then pursue a numerical study of the system to determine the triviality and vacuum stability bounds, using a scan of 10^4 random set of points to fix the initial conditions. We show that, if there is no mixing in the scalar sector, the top Yukawa coupling drives the quartic Higgs coupling to negative values in the ultraviolet and, as for the SM, the effective potential develops an instability below the Planck scale. However, for a mixing angle -0.35 \\alt \\alpha \\alt -0.02 or 0.01 \\alt \\alpha \\alt 0.35, with the new scalar mass in the range 500 GeV \\alt m_{h"} \\alt 8 TeV, the SM^{++} ground state can be absolutely stable up to the Planck scale. These results are largely independent of TeV-scale free parameters in the model: the mass of the non-anomalous U(1) gauge boson and its branching fractions.

  18. Various superstable synchronous phenomena in switch-coupled relaxation oscillators

    Microsoft Academic Search

    Fumitaka Komatsu; Hiroyuki Torikai; Toshimichi Saito

    2001-01-01

    This paper considers synchronous phenomena from switch-coupled relaxation oscillators. This system exhibits a variety of interesting superstable synchronous phenomena. Using a hybrid return map, we can analyze the phenomena almost completely. Using a simple circuit, typical phenomena are verified in the laboratory

  19. Superstable Synchronous Phenomena of Switch-Coupled Relaxation Oscillators

    Microsoft Academic Search

    Toshimichi SAITO; Fumitaka KOMATSU; Hiroyuki TORIKAI

    2002-01-01

    SUMMARY As two simple relaxation oscillators are coupled by periodical and instantaneous switching, the system exhibits rich superstable synchronous phenomena. In order to analyze the phenomena, we derive a hybrid return map of real and binary variables;and give theoretical results for (1) superstability of the synchronous phenomena and (2) period of the synchronous phenomena as a function of the parameters.

  20. Improved Aerogel Vacuum Thermal Insulation

    NASA Technical Reports Server (NTRS)

    Ruemmele, Warren P.; Bue, Grant C.

    2009-01-01

    An improved design concept for aerogel vacuum thermal-insulation panels calls for multiple layers of aerogel sandwiched between layers of aluminized Mylar (or equivalent) poly(ethylene terephthalate), as depicted in the figure. This concept is applicable to both the rigid (brick) form and the flexible (blanket) form of aerogel vacuum thermal-insulation panels. Heretofore, the fabrication of a typical aerogel vacuum insulating panel has involved encapsulation of a single layer of aerogel in poly(ethylene terephthalate) and pumping of gases out of the aerogel-filled volume. A multilayer panel according to the improved design concept is fabricated in basically the same way: Multiple alternating layers of aerogel and aluminized poly(ethylene terephthalate) are assembled, then encapsulated in an outer layer of poly(ethylene terephthalate), and then the volume containing the multilayer structure is evacuated as in the single-layer case. The multilayer concept makes it possible to reduce effective thermal conductivity of a panel below that of a comparable single-layer panel, without adding weight or incurring other performance penalties. Implementation of the multilayer concept is simple and relatively inexpensive, involving only a few additional fabrication steps to assemble the multiple layers prior to evacuation. For a panel of the blanket type, the multilayer concept, affords the additional advantage of reduced stiffness.