Sample records for closed-field unbalanced magnetron

  1. Structural and tribological properties of CrTiAlN coatings on Mg alloy by closed-field unbalanced magnetron sputtering ion plating

    NASA Astrophysics Data System (ADS)

    Shi, Yongjing; Long, Siyuan; Yang, Shicai; Pan, Fusheng

    2008-09-01

    In this paper, a series of multi-layer hard coating system of CrTiAlN has been prepared by closed-field unbalanced magnetron sputtering ion plating (CFUBMSIP) technique in a gas mixture of Ar + N 2. The coatings were deposited onto AZ31 Mg alloy substrates. During deposition step, technological temperature and metallic atom concentration of coatings were controlled by adjusting the currents of different metal magnetron targets. The nitrogen level was varied by using the feedback control of plasma optical emission monitor (OEM). The structural, mechanical and tribological properties of coatings were characterized by means of X-ray photoelectron spectrometry, high-resolution transmission electron microscope, field emission scanning electron microscope (FESEM), micro-hardness tester, and scratch and ball-on-disc tester. The experimental results show that the N atomic concentration increases and the oxide on the top of coatings decreases; furthermore the modulation period and the friction coefficient decrease with the N 2 level increasing. The outstanding mechanical property can be acquired at medium N 2 level, and the CrTiAlN coatings on AZ31 Mg alloy substrates outperform the uncoated M42 high speed steel (HSS) and the uncoated 316 stainless steel (SS).

  2. Multi-cathode unbalanced magnetron sputtering systems

    NASA Technical Reports Server (NTRS)

    Sproul, William D.

    1991-01-01

    Ion bombardment of a growing film during deposition is necessary in many instances to ensure a fully dense coating, particularly for hard coatings. Until the recent advent of unbalanced magnetron (UBM) cathodes, reactive sputtering had not been able to achieve the same degree of ion bombardment as other physical vapor deposition processes. The amount of ion bombardment of the substrate depends on the plasma density at the substrate, and in a UBM system the amount of bombardment will depend on the degree of unbalance of the cathode. In multi-cathode systems, the magnetic fields between the cathodes must be linked to confine the fast electrons that collide with the gas atoms. Any break in this linkage results in electrons being lost and a low plasma density. Modeling of the magnetic fields in a UBM cathode using a finite element analysis program has provided great insight into the interaction between the magnetic fields in multi-cathode systems. Large multi-cathode systems will require very strong magnets or many cathodes in order to maintain the magnetic field strength needed to achieve a high plasma density. Electromagnets offer the possibility of independent control of the plasma density. Such a system would be a large-scale version of an ion beam enhanced deposition (IBED) system, but, for the UBM system where the plasma would completely surround the substrate, the acronym IBED might now stand for Ion Blanket Enhanced Deposition.

  3. Unbalanced field RF electron gun

    DOEpatents

    Hofler, Alicia

    2013-11-12

    A design for an RF electron gun having a gun cavity utilizing an unbalanced electric field arrangement. Essentially, the electric field in the first (partial) cell has higher field strength than the electric field in the second (full) cell of the electron gun. The accompanying method discloses the use of the unbalanced field arrangement in the operation of an RF electron gun in order to accelerate an electron beam.

  4. Characteristics of W Doped Nanocrystalline Carbon Films Prepared by Unbalanced Magnetron Sputtering.

    PubMed

    Park, Yong Seob; Park, Chul Min; Kim, Nam-Hoon; Kim, Jae-Moon

    2016-05-01

    Nanocrystalline tungsten doped carbon (WC) films were prepared by unbalanced magnetron sputtering. Tungsten was used as the doping material in carbon thin films with the aim of application as a contact strip in an electric railway. The structural, physical, and electrical properties of the fabricated WC films with various DC bias voltages were investigated. The films had a uniform and smooth surface. Hardness and frication characteristics of the films were improved, and the resistivity and sheet resistance decreased with increasing negative DC bias voltage. These results are associated with the nanocrystalline WC phase and sp(2) clusters in carbon networks increased by ion bombardment enhanced with increasing DC bias voltage. Consequently, the increase of sp(2) clusters containing WC nanocrystalline in the carbon films is attributed to the improvement in the physical and electrical properties.

  5. Properties of Diamond-Like Carbon Films Synthesized by Dual-Target Unbalanced Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    Liu, Cui; Li, Guo-Qing; Gou, Wei; Mu, Zong-Xin; Zhang, Cheng-Wu

    2004-11-01

    Smooth, dense and uniform diamond-like carbon films (DLC films) for industrial applications have successfully been prepared by dual-target unbalanced magnetron sputtering and the DLC characteristics of the films are confirmed by Raman spectra. It is found that the sputtering current of target plays an important role in the DLC film deposition. Deposition rate of 3.5 μm/h is obtained by using the sputtering current of 30 A. The friction coefficient of the films is 0.2-0.225 measured by using a pin-on-disc microtribometer. The structure of the films tends to have a growth of sp3 bonds content at high sputtering current. The compressive residual stress in the films increases with the increasing sputtering current of the target.

  6. Nanoscale multilayer Me-graphite coatings grown by combined steered cathodic arc/unbalanced magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Kok, Yin Nan

    Low friction, nanoscale multilayer carbon/chromium (C/Cr) coatings were successfully deposited by the combined steered cathodic arc/unbalanced magnetron sputtering technique (also known as Arc Bond Sputtering or ABS) using a Hauzer HTC 1000-4 PVD coater. The work described in this thesis has been directed towards understanding the effect of ion irradiation on the composition, microstructure, and functional properties of C/Cr coatings. This has been achieved by varying the bias voltage, U[B], over a wide range between -65 V and -550 V. C/Cr coatings were deposited in three major steps: (i) Cr+ ion etching using a steered cathodic arc discharge at a substrate bias voltage of -1200 V, (ii) deposition of a 0.25 mum thick CrN base layer by reactive unbalanced magnetron sputtering to enhance the adhesion, and (iii) deposition of C/Cr coatings by unbalanced magnetron sputtering from three graphite targets and one chromium target at 260°C. The coatings were deposited at different bias voltages (U[B]) from -65 V to -550 V in a non-reactive Ar atmosphere.C/Cr coatings exhibit excellent adhesion (critical load, L[C] > 70 N), with hardness ranging from 6.8 to 25.1 GPa depending on the bias voltage. The friction coefficient of C/Cr coatings was found to reduce from 0.22 to 0.16 when the bias voltage was increased from U[B] = -65 to -95 V. The relevance of C/Cr coatings for actual practical applications was demonstrated using dry high-speed milling trials on automotive aluminium alloy (Al-Si8Cu3Fe). The results showed that C/Cr coated cemented carbide ball-nose end mills prepared at U[B] = -95 V (70 at.% C, 30 at.% Cr) enhance the tool performance and the tool life compared to the uncoated tools by a factor of two, suggesting the potential for use in dry high-speed machining of "sticky" alloys such as aluminum. Different film morphologies were observed in the investigated bias voltage range between U[B] = -65 and -550 V using XTEM. With increasing bias voltage from U[B] = -65

  7. Surface treatment effect on Si (111) substrate for carbon deposition using DC unbalanced magnetron sputtering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Aji, A. S., E-mail: aji.ravazes70@gmail.com; Sahdan, M. F.; Hendra, I. B.

    In this work, we studied the effect of HF treatment in silicon (111) substrate surface for depositing thin layer carbon. We performed the deposition of carbon by using DC Unbalanced Magnetron Sputtering with carbon pallet (5% Fe) as target. From SEM characterization results it can be concluded that the carbon layer on HF treated substrate is more uniform than on substrate without treated. Carbon deposition rate is higher as confirmed by AFM results if the silicon substrate is treated by HF solution. EDAX characterization results tell that silicon (111) substrate with HF treatment have more carbon fraction than substrate withoutmore » treatment. These results confirmed that HF treatment on silicon Si (111) substrates could enhance the carbon deposition by using DC sputtering. Afterward, the carbon atomic arrangement on silicon (111) surface is studied by performing thermal annealing process to 900 °C. From Raman spectroscopy results, thin film carbon is not changing until 600 °C thermal budged. But, when temperature increase to 900 °C, thin film carbon is starting to diffuse to silicon (111) substrates.« less

  8. Carbon film deposition on SnO{sub 2}/Si(111) using DC unbalanced magnetron sputtering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Aji, A. S.; Darma, Y.

    In this paper, carbon deposition on SnO{sub 2} layer using DC unbalanced magnetron-sputtering technique at low temperature has been systematically studied. Sputtering process were carried out at pressure of 4.6×10{sup −2} Torr by keeping the substrate temperature at 300 °C. SnO{sub 2} were growth on silicon (111) substrate using thermal evaporation and continuing with dry oxidation of Sn at 225 °C. Thermal evaporation for high purity Sn was conducted by maintain the current source as high as 40 ampere. The quality of SnO{sub 2} on Si(111) and the characteristic of carbon thin film on SnO{sub 2} were analized by meanmore » XRD, FTIR and Raman spectra. XRD analysis shows that SnO{sub 2} film is growth uniformly on Si(111). FTIR and Raman spectra confirm the formation of thin film carbon on SnO{sub 2}. Additionally, thermal annealing for some sample series have been performed to study their structural stability. The change of atomic structure due to thermal annealing were analized by Raman and XRD spectra.« less

  9. Deposition and characterization of TiAlSiN nanocomposite coatings prepared by reactive pulsed direct current unbalanced magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Barshilia, Harish C.; Ghosh, Moumita; Shashidhara; Ramakrishna, Raja; Rajam, K. S.

    2010-08-01

    This work reports the performance of high speed steel drill bits coated with TiAlSiN nanocomposite coating at different Si contents (5.5-8.1 at.%) prepared using a four-cathode reactive pulsed direct current unbalanced magnetron sputtering system. The surface morphology of the as-deposited coatings was characterized using field emission scanning electron microscopy. The crystallographic structure, chemical composition and bonding structure were evaluated using X-ray diffraction, energy-dispersive X-ray analysis, X-ray photoelectron spectroscopy, respectively. The corrosion behavior, mechanical properties and thermal stability of TiAlSiN nanocomposite coatings were also studied using potentiodynamic polarization, nanoindentation and Raman spectroscopy, respectively. The TiAlSiN coating thickness was approximately 2.5-2.9 μm. These coatings exhibited a maximum hardness of 38 GPa at a silicon content of approximately 6.9 at.% and were stable in air up to 850 °C. For the performance evaluation, the TiAlSiN coated drills were tested under accelerated machining conditions by drilling a 12 mm thick 304 stainless steel plate. Under dry conditions the uncoated drill bits failed after drilling 50 holes, whereas, TiAlSiN coated drill bits (Si = 5.5 at.%) drilled 714 holes before failure. Results indicated that for TiAlSiN coated drill bits the tool life increased by a factor of more than 14.

  10. Time dependence of carbon film deposition on SnO{sub 2}/Si using DC unbalanced magnetron sputtering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Alfiadi, H., E-mail: yudi@fi.itb.ac.id; Aji, A. S., E-mail: yudi@fi.itb.ac.id; Darma, Y., E-mail: yudi@fi.itb.ac.id

    Carbon deposition on SnO{sub 2} layer has been demonstrated at low temperature using DC unbalanced magnetron-sputtering technique for various time depositions. Before carbon sputtering process, SnO{sub 2} thin layer is grown on silicon substrate by thermal evaporation method using high purity Sn wire and then fully oxidizes by dry O{sub 2} at 225°C. Carbon sputtering process was carried out at pressure of 4.6×10{sup −2} Torr by keeping the substrate temperature of 300 °C for sputtering deposition time of 1 to 4 hours. The properties of SnO{sub 2}/Si structure and carbon thin film on SnO{sub 2} is characterized using SEM, EDAX,more » XRD, FTIR, and Raman Spectra. SEM images and XRD spectra show that SnO2 thin film has uniformly growth on Si substrate and affected by annealing temperature. Raman and FTIR results confirm the formation of carbon-rich thin film on SnO{sub 2}. In addition, XRD spectra indicate that some structural change occur by increasing sputtering deposition time. Furthermore, the change of atomic structure due to the thermal annealing is analized by XRD spectra and Raman spectroscopy.« less

  11. Characterization of polycrystalline nickel cobaltite nanostructures prepared by DC plasma magnetron co-sputtering for gas sensing applications

    NASA Astrophysics Data System (ADS)

    Hammadi, Oday A.; Naji, Noor E.

    2018-03-01

    In this work, a gas sensor is fabricated from polycrystalline nickel cobaltite nano films deposited on transparent substrates by closed-field unbalanced dual-magnetrons (CFUBDM) co-sputtering technique. Two targets of nickel and cobalt are mounted on the cathode of discharge system and co-sputtered by direct current (DC) argon discharge plasma in presence of oxygen as a reactive gas. The total gas pressure is 0.5 mbar and the mixing ratio of Ar:O2 gases is 5:1. The characterization measurements performed on the prepared films show that their transmittance increases with the incident wavelength, the polycrystalline structure includes 5 crystallographic planes, the average particle size is about 35 nm, the electrical conductivity is linearly increasing with increasing temperature, and the activation energy is about 0.41 eV. These films show high sensitivity to ethanol vapor.

  12. Influence of substrate bias voltage on structure and properties of the CrAlN films deposited by unbalanced magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Lv, Yanhong; Ji, Li; Liu, Xiaohong; Li, Hongxuan; Zhou, Huidi; Chen, Jianmin

    2012-02-01

    The CrAlN films were deposited on silicon and stainless steel substrates by unbalanced magnetron sputtering system. The influence of substrate bias on deposition rate, composition, structure, morphology and properties of the CrAlN films was investigated. The results showed that, with the increase of the substrate bias voltage, the deposition rate decreased accompanied by a change of the preferred orientation of the CrAlN film from (2 2 0) to (2 0 0). The grain size and the average surface roughness of the CrAlN films declined as the bias voltage increases above -100 V. The morphology of the films changed from obviously columnar to dense glass-like structure with the increase of the bias voltage from -50 to -250 V. Meanwhile, the films deposited at moderate bias voltage had better mechanical and tribological properties, while the films deposited at higher bias voltage showed better corrosion resistance. It was found that the corrosion resistance improvement was not only attributed to the low pinhole density of the film, but also to chemical composition of films.

  13. Magnetron magnetic priming for rapid startup and noise reduction

    NASA Astrophysics Data System (ADS)

    Neculaes, Vasile Bogdan

    The magnetron is a vacuum electronics crossed-field device: perpendicular electric and magnetic fields determine the electron dynamics. Compactness, efficiency and reliability make magnetrons suitable for a wide range of military and civilian applications: radar, industrial heating, plasma sources, and medical accelerators. The most ubiquitous use of magnetrons is as the microwave power source in microwave ovens, operating at 2.45 GHz and delivering about 800--1000 W. University of Michigan and several other research programs are actively pursuing the development of GW range relativistic magnetrons. This dissertation presents experimental and computational results concerning innovative techniques to improve magnetron noise, startup and mode stability. The DC-operated oven magnetron studies performed at University of Michigan opened new directions by utilizing azimuthally varying magnetic fields (magnetic priming). Magnetic priming for rapid startup in an N-cavity magnetron operating in the pi-mode is based on implementation of an axial magnetic field with N/2 azimuthal periods, to prebunch the electrons in the desired number of spokes (N/2). Experiments with magnetic priming on DC oven magnetrons using perturbing magnets added on the upper existing magnet of the magnetron showed rapid startup (pi-mode oscillation observed at low currents) and up to 35 dB noise reduction (close to the carrier and in sidebands). A complex 3-dimensional (3D) ICEPIC computational model recovered the oven magnetron magnetic priming experimental results: rapid electron prebunching due to presence of perturbing magnets, fast startup and tendency towards a lower noise state. Simulations in 6-cavity relativistic magnetrons show that ideal magnetic priming causes fast startup, rapid mode growth (with radial electron diffusion) and suppression of mode competition. A highly idealized model (planar, crossed-field, non-resonant, non-relativistic structure) using single particle dynamics showed

  14. Corrosion resistance of zirconium oxynitride coatings deposited via DC unbalanced magnetron sputtering and spray pyrolysis-nitriding

    NASA Astrophysics Data System (ADS)

    Cubillos, G. I.; Bethencourt, M.; Olaya, J. J.

    2015-02-01

    ZrOxNy/ZrO2 thin films were deposited on stainless steel using two different methods: ultrasonic spray pyrolysis-nitriding (SPY-N) and the DC unbalanced magnetron sputtering technique (UBMS). Using the first method, ZrO2 was initially deposited and subsequently nitrided in an anhydrous ammonia atmosphere at 1023 K at atmospheric pressure. For UBMS, the film was deposited in an atmosphere of air/argon with a Φair/ΦAr flow ratio of 3.0. Structural analysis was carried out through X-ray diffraction (XRD), and morphological analysis was done through scanning electron microscopy (SEM) and atomic force microscopy (AFM). Chemical analysis was carried out using X-ray photoelectron spectroscopy (XPS). ZrOxNy rhombohedral polycrystalline film was produced with spray pyrolysis-nitriding, whereas using the UBMS technique, the oxynitride films grew with cubic Zr2ON2 crystalline structures preferentially oriented along the (2 2 2) plane. Upon chemical analysis of the surface, the coatings exhibited spectral lines of Zr3d, O1s, and N1s, characteristic of zirconium oxynitride/zirconia. SEM analysis showed the homogeneity of the films, and AFM showed morphological differences according to the deposition technique of the coatings. Zirconium oxynitride films enhanced the stainless steel's resistance to corrosion using both techniques. The protective efficacy was evaluated using electrochemical techniques based on linear polarization (LP). The results indicated that the layers provide good resistance to corrosion when exposed to chloride-containing media.

  15. Reconstruction of the static magnetic field of a magnetron

    NASA Astrophysics Data System (ADS)

    Krüger, Dennis; Köhn, Kevin; Gallian, Sara; Brinkmann, Ralf Peter

    2018-06-01

    The simulation of magnetron discharges requires a quantitatively correct mathematical model of the magnetic field structure. This study presents a method to construct such a model on the basis of a spatially restricted set of experimental data and a plausible a priori assumption on the magnetic field configuration. The example in focus is that of a planar circular magnetron. The experimental data are Hall probe measurements of the magnetic flux density in an accessible region above the magnetron plane [P. D. Machura et al., Plasma Sources Sci. Technol. 23, 065043 (2014)]. The a priori assumption reflects the actual design of the device, and it takes the magnetic field emerging from a center magnet of strength m C and vertical position d C and a ring magnet of strength m R , vertical position d R , and radius R. An analytical representation of the assumed field configuration can be formulated in terms of generalized hypergeometric functions. Fitting the ansatz to the experimental data with a least square method results in a fully specified analytical field model that agrees well with the data inside the accessible region and, moreover, is physically plausible in the regions outside of it. The outcome proves superior to the result of an alternative approach which starts from a multimode solution of the vacuum field problem formulated in terms of polar Bessel functions and vertical exponentials. As a first application of the obtained field model, typical electron and ion Larmor radii and the gradient and curvature drift velocities of the electron guiding center are calculated.

  16. Effects of magnetic flux density and substrate bias voltage on Ni films prepared on a flexible substrate material using unbalanced magnetron sputtering assisted by inductively coupled plasma

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Koda, Tatsunori; Toyota, Hiroshi, E-mail: h.toyota.za@it-hiroshima.ac.jp

    The authors fabricated Ni films on a flexible substrate material using unbalanced magnetron sputtering assisted by inductively coupled plasma. The effects of magnetic flux density B{sub C} and substrate DC bias voltage V{sub S} on the Ni film structures were investigated. For V{sub S} = −40 V, the average surface grain size D{sub G} measured by atomic force microscopy for B{sub C} = 0, 3, and 5 mT was 88.2, 95.4, and 104.4 nm, respectively. In addition, D{sub G} increased with V{sub S}. From x-ray diffraction measurements, the (111) and (200) peaks were clearly visible for the fabricated Ni films. The ratio of the integrated intensities ofmore » I(111)/I(200) increased with V{sub S}. For V{sub S} = −40 V and B{sub C} = 3 mT, a film resistivity ρ of 8.96 × 10{sup −6} Ω cm was observed, which is close to the Ni bulk value of 6.84 × 10{sup −6} Ω cm. From these results, the authors determined that the structure of the fabricated Ni films on the flexible substrate material was affected by the values of B{sub C} and V{sub S}.« less

  17. Satellite Power System (SPS) magnetron tube assessment study

    NASA Technical Reports Server (NTRS)

    Brown, W. C.

    1981-01-01

    The data base was extended with respect to the magnetron directional amplifier and its operating parameters that are pertinent to its application in the solar power satellite. On the basis of the resulting extended data base the design of a magnetron was outlined that would meet the requirements of the SPS application and a technology program was designed that would result in its development. The proposed magnetron design for the SPS is a close scale of the microwave oven magnetron, and resembles it closely physically and electrically.

  18. Improving optical properties of silicon nitride films to be applied in the middle infrared optics by a combined high-power impulse/unbalanced magnetron sputtering deposition technique.

    PubMed

    Liao, Bo-Huei; Hsiao, Chien-Nan

    2014-02-01

    Silicon nitride films are prepared by a combined high-power impulse/unbalanced magnetron sputtering (HIPIMS/UBMS) deposition technique. Different unbalance coefficients and pulse on/off ratios are applied to improve the optical properties of the silicon nitride films. The refractive indices of the Si3N4 films vary from 2.17 to 2.02 in the wavelength ranges of 400-700 nm, and all the extinction coefficients are smaller than 1×10(-4). The Fourier transform infrared spectroscopy and x-ray diffractometry measurements reveal the amorphous structure of the Si3N4 films with extremely low hydrogen content and very low absorption between the near IR and middle IR ranges. Compared to other deposition techniques, Si3N4 films deposited by the combined HIPIMS/UBMS deposition technique possess the highest refractive index, the lowest extinction coefficient, and excellent structural properties. Finally a four-layer coating is deposited on both sides of a silicon substrate. The average transmittance from 3200 to 4800 nm is 99.0%, and the highest transmittance is 99.97% around 4200 nm.

  19. The Pulsed Cylindrical Magnetron for Deposition

    NASA Astrophysics Data System (ADS)

    Korenev, Sergey

    2012-10-01

    The magnetron sputtering deposition of films and coatings broadly uses in microelectronics, material science, environmental applications and etc. The rate of target evaporation and time for deposition of films and coatings depends on magnetic field. These parameters link with efficiency of gas molecules ionization by electrons. The cylindrical magnetrons use for deposition of films and coatings on inside of pipes for different protective films and coatings in oil, chemical, environmental applications. The classical forming of magnetic field by permanent magnets or coils for big and long cylindrical magnetrons is complicated. The new concept of pulsed cylindrical magnetron for high rate deposition of films and coating for big and long pipes is presented in this paper. The proposed cylindrical magnetron has azimuthally pulsed high magnetic field, which allows forming the high ionized plasma and receiving high rate of evaporation material of target (central electrode). The structure of proposed pulsed cylindrical magnetron sputtering system is given. The main requirements to deposition system are presented. The preliminary data for forming of plasma and deposition of Ta films and coatings on the metal pipers are discussed. The comparison of classical and proposed cylindrical magnetrons is given. The analysis of potential applications is considered.

  20. Spectroscopy analysis of graphene like deposition using DC unbalanced magnetron sputtering on γ‐Al{sub 2}O{sub 3} buffer layer

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Aji, A. S., E-mail: yudi@fi.itb.ac.id; Darma, Y., E-mail: yudi@fi.itb.ac.id

    In this work, graphene-like deposition using DC unbalanced magnetron-sputtering technique on γ‐Al{sub 2}O{sub 3} layer at low temperature has been systematically studied. The γ‐Al{sub 2}O{sub 3} was growth on silicon substrate using thermal evaporation of Al wire and continuing with dry oxidation of Al at 550 °C. Sputtering process were carried out using Fe-doped carbon pellet as a target by maintain the chamber pressure of 4.6×10{sup −2} Torr at substrate temperature of 300 °C for time deposition range of 1 to 4 hours. The quality of Al{sub 2}O{sub 3} on Si(100) and the characteristic of carbon thin film on γ‐Al{submore » 2}O{sub 3} were analized by mean XRD, opctical microscopy, EDAX, FTIR, and Raman spectra. XRD and optical microscopy analysis shows that Al{sub 2}O{sub 3} film is growth uniformly on Si substrate and forming the γ phase of Al{sub 2}O{sub 3}. Raman and FTIR spectra confirm the formation of graphene like carbon layer on Al{sub 2}O{sub 3}. Additionally, thermal annealing for some sample series have been performed to study their structural stability. The change of atomic structure due to thermal annealing were analized by XRD spectra. The quality and the number of graphene layers are investigated by using Raman spectra peaks analysis.« less

  1. The current-density distribution in a pulsed dc magnetron deposition discharge

    NASA Astrophysics Data System (ADS)

    Vetushka, Alena; Bradley, James W.

    2007-04-01

    Using a carefully constructed magnetic probe (a B-dot probe) the spatial and temporal evolution of the perturbation in the magnetic field ΔB in an unbalanced pulsed dc magnetron has been determined. The plasma was run in argon at a pressure of 0.74 Pa and the plasma ions sputtered a pure graphite target. The pulse frequency and duty were set at 100 kHz and 55%, respectively. From the ΔB measurements (measured with magnitudes up to about 0.01 mT) the axial, azimuthal and radial components of the total current density j in the plasma bulk were determined. In the plasma 'on' phase, the axial current density jz has a maximum value of approximately 200 A m-2 above the racetrack region, while high values in the azimuthal current density jΦ are distributed in a region from 1 to 3 cm into the bulk plasma with jΦ exceeding 350 A m-2. In the 'off' phase of the plasma, jz decays almost instantaneously (at least within the 100 ns time-resolution of the ΔB measurements) as the electric field collapses; however, jΦ decays with a characteristic time constant of about 1 µs. This slow decay can be attributed to the presence of decaying Grad-B and curvature drifts, with their rates controlled by the decay in the plasma density. A comparison between axial and azimuthal current densities in the plasma 'on' time, when the plasma is being driven, strongly indicates that classical transport does not operate in the magnetron discharge.

  2. Method and apparatus for improved high power impulse magnetron sputtering

    DOEpatents

    Anders, Andre

    2013-11-05

    A high power impulse magnetron sputtering apparatus and method using a vacuum chamber with a magnetron target and a substrate positioned in the vacuum chamber. A field coil being positioned between the magnetron target and substrate, and a pulsed power supply and/or a coil bias power supply connected to the field coil. The pulsed power supply connected to the field coil, and the pulsed power supply outputting power pulse widths of greater that 100 .mu.s.

  3. Experimental radiation cooled magnetrons for space

    NASA Astrophysics Data System (ADS)

    Brown, W. C.; Pollock, M.

    The heat disposal problem that occurs in the microwave generator of the Solar Power Satellite when it converts dc power from solar photovoltaic arrays into microwave power for transmission to earth is examined. A theoretical study is made of the radiation cooling of a magnetron directional amplifier, and some experimental data obtained from the QKH 2244 magnetron are presented. This instrument is an unpackaged microwave oven magnetron to which an anodized aluminum radiator has been attached and whose magnetic field is supplied by special samarium cobalt magnets.

  4. RF Priming Experiments and Simulations of Magnetic Priming in Relativistic Magnetrons

    NASA Astrophysics Data System (ADS)

    White, W. M.; Gilgenbach, R. M.; Jones, M. C.; Neculaes, V. B.; Lau, Y. Y.; Jordan, N.; Pengvanich, P.; Edgar, R.; Hoff, B.; Spencer, T. A.; Price, D.

    2004-11-01

    We investigate 2 priming techniques in relativistic magnetrons for rapid startup and mode-locking: RF priming experiments with 0.1-1 MW from a 2nd magnetron; Magnetic-priming simulations by azimuthally-varying-axial magnetic field. Experiments utilize MELBA-C with a Titan 6-vane magnetron: V = -300kV, I = 1-10kA, e-beam T = 0.5 μs, microwave power = 100-500 MW, f= 1-1.3 GHz, base vacuum= 8.5 x 10-10 Torr. The AFRL RF priming magnetron is at 0.1-2 MW, 3 μsec, 1.27-1.32 GHz. About 0.2-0.3 MW is injected into 1 of 3 open coupling slots in the relativistic magnetron. Analysis of the relativistic magnetron's microwave output shows a clear effect of RF priming. Simulations of magnetic priming in the pi-mode are run in MAGIC code by imposing N/2 azimuthal-variations in the axial magnetic field of an N-vane magnetron. Faster startup and mode-locking are simulated by rapid-electron spoke formation and excitation of RF fields.

  5. Stability of Brillouin flow in planar, conventional, and inverted magnetrons

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Simon, D. H.; Lau, Y. Y.; Greening, G.

    2015-08-15

    The Brillouin flow is the prevalent flow in crossed-field devices. We systematically study its stability in the conventional, planar, and inverted magnetron geometry. To investigate the intrinsic negative mass effect in Brillouin flow, we consider electrostatic modes in a nonrelativistic, smooth bore magnetron. We found that the Brillouin flow in the inverted magnetron is more unstable than that in a planar magnetron, which in turn is more unstable than that in the conventional magnetron. Thus, oscillations in the inverted magnetron may startup faster than the conventional magnetron. This result is consistent with simulations, and with the negative mass property inmore » the inverted magnetron configuration. Inclusion of relativistic effects and electromagnetic effects does not qualitatively change these conclusions.« less

  6. Recirculating planar magnetrons: simulations and experiment

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Franzi, Matthew; Gilgenbach, Ronald; French, David

    2011-07-01

    The Recirculating Planar Magnetron (RPM) is a novel crossed-field device whose geometry is expected to reduce thermal load, enhance current yield as well as ease the geometric limitations in scaling to high RF frequencies as compared to the conventional cylindrical magnetrons. The RPM has two different adaptations: A. Axial B field and radial E field; B. Radial B field and axial E field. The preliminary configuration (A) to be used in experiments at the University of Michigan consists of two parallel planar sections which join on either end by cylindrical regions to form a concentric extruded ellipse. Similar to conventionalmore » magnetrons, a voltage across the AK gap in conjunction with an axial magnetic field provides the electrons with an ExB drift. The device is named RPM because the drifting electrons recirculate from one planar region to the other. The drifting electrons interact with the resonantly tuned slow wave structure on the anode causing spoke formation. These electron spokes drive a RF electric field in the cavities from which RF power may be extracted to Waveguides. The RPM may be designed in either a conventional configuration with the anode on the outside, for simplified extraction, or as an inverted magnetron with the anode at the inner conductor, for fast start-up. Currently, experiments at the Pulsed Power and Microwave Laboratory at the University of Michigan are in the setup and design phase. A conventional RPM with planar cavities is to be installed on the Michigan Electron Long Beam Accelerator (MELBA) and is anticipated to operate at -200kV, 0.2T with a beam current of 1-10 kA at 1GHz. The conventional RPM consists of 12 identical planar cavities, 6 on each planar side, with simulated quality factor of 20.« less

  7. Experimental study on an S-band near-field microwave magnetron power transmission system on hundred-watt level

    NASA Astrophysics Data System (ADS)

    Zhang, Biao; Jiang, Wan; Yang, Yang; Yu, Chengyang; Huang, Kama; Liu, Changjun

    2015-11-01

    A multi-magnetron microwave source, a metamaterial transmitting antenna, and a large power rectenna array are presented to build a near-field 2.45 GHz microwave power transmission system. The square 1 m2 rectenna array consists of sixteen rectennas with 2048 Schottky diodes for large power microwave rectifying. It receives microwave power and converts them into DC power. The design, structure, and measured performance of a unit rectenna as well as the entail rectenna array are presented in detail. The multi-magnetron microwave power source switches between half and full output power levels, i.e. the half-wave and full-wave modes. The transmission antenna is formed by a double-layer metallic hole array, which is applied to combine the output power of each magnetron. The rectenna array DC output power reaches 67.3 W on a 1.2 Ω DC load at a distance of 5.5 m from the transmission antenna. DC output power is affected by the distance, DC load, and the mode of microwave power source. It shows that conventional low power Schottky diodes can be applied to a microwave power transmission system with simple magnetrons to realise large power microwave rectifying.

  8. Development of high-vacuum planar magnetron sputtering using an advanced magnetic field geometry

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ohno, Takahiro; Yagyu, Daisuke; Saito, Shigeru, E-mail: saito@ee.kagu.tus.ac.jp

    2015-11-15

    A permanent magnet in a new magnetic field geometry (namely, with the magnetization in the radial direction) was fabricated and used for high-vacuum planar magnetron sputtering using Penning discharge. Because of the development of this magnet, the discharge current and deposition rate were increased two to three times in comparison with the values attainable with a magnet in the conventional geometry. This improvement was because the available space for effective discharge of the energetic electrons for the ionization increased because the magnetic field distribution increased in both the axial and radial directions of discharge.

  9. Multi-Frequency Recirculating Planar Magnetrons

    NASA Astrophysics Data System (ADS)

    Greening, Geoffrey Bruce

    The cavity magnetron is generally accepted as the standard for compactness and high microwave power with applications in industry, science, and defense, with the latter including counter-electronics. In this application, magnetrons are limited because they are narrowband devices. To expand the range of frequencies that can be produced using a single magnetron, a novel multi-frequency variant of the Recirculating Planar Magnetron (RPM) was designed, fabricated, and experimentally demonstrated. This multi-frequency RPM (MFRPM) was the first high-power magnetron capable of generating multiple microwave frequencies simultaneously and demonstrated the first known instance of harmonic frequency-locking in a magnetron. The MFRPM design consisted of two planar cavity arrays coupled by cylindrical electron recirculation bends. The two arrays formed a 1 GHz L-Band Oscillator (LBO) and a 2 GHz S-Band Oscillator (SBO). Experiments were conducted using a 0.1-0.3 T axial magnetic field produced using a pulsed pair of Helmholtz coils and a -300 kV, 200-400 ns, 1-5 kA pulse applied to a Mode-Control Cathode (MCC) using the MELBA-C Marx generator. Six experimental configurations were tested using three anodes (the isolated LBO, the isolated SBO, and the MFRPM), two microwave loads (a standard, matched load, and a waveguide taper load used to characterize the LBO frequency harmonics), and two axial magnetic fields (uniform and nonuniform). Using these configurations, an in-depth characterization of MFRPM operation determined 1) the identity of the observed electromagnetic modes, and the degree of mode competition, 2) the frequencies, powers, and other electrical characteristics associated with those modes and the LBO frequency harmonics, 3) the magnetic fields corresponding to optimal operation, 4) the operational impact of a nonuniform axial magnetic field, and 5) the origin and performance characteristics of a novel harmonic frequency-locked state observed in the MFRPM. The

  10. An investigation of material properties and tribological performance of magnetron sputtered thin film coatings

    NASA Astrophysics Data System (ADS)

    Singh, Harpal

    This dissertation is divided into two categories based upon lubrication functionality and its application. The categories are: Dry film lubrication and Fluid film lubrication with thin film coatings. Thin film coatings examined in this work were deposited using closed field unbalanced magnetron sputtering and RF-DC coupled magnetron sputtering systems. In Dry/Solid film lubrication, the mechanical, structural and tribological properties of two Molybdenum disulphide (MoS2) based coatings are examined and evaluated. Among the two coatings, one coating is doped with Ti (Ti-MoS2) and the other is a combination of metal, lubricant and oxide (Sb2O3/Au - MoS2). These coatings are known to provide low friction in vacuum environments. The goal of this work was to evaluate friction and wear performance of MoS2 doped coatings in unidirectional and reciprocating sliding contact under different environmental conditions. Sliding contact results showed friction and wear dependence on temperature and humidity. The formation and removal of transfer films and the recrystallization and reorientation of basal layers on the steel counterface was observed as the mechanism for low friction. Structural analysis revealed a relationship between the microstructural properties and tribological performance. It was also observed that the addition of dopants (Ti, Au, Sb 2O3) improved the mechanical properties as compared to pure MoS2 coatings. Further, the rolling contact performance of the coatings was measured on a five ball on rod tribometer and a Thrust bearing tribometer under vacuum and air environments. The rolling contact experiments indicated that life of the rolling components depend on the amount of material present between the contacts. Fluid film lubrication with thin film coatings investigates the possibilities to improve the performance and durability of tribological components when oils and thin films are synergistically coupled. In this work, the ability of a Diamond Like Carbon

  11. Bloch equations applied to ion cyclotron resonance spectroscopy: Broadband interconversion between magnetron and cyclotron motion for ion axialization

    NASA Astrophysics Data System (ADS)

    Guan, Shenheng; Marshall, Alan G.

    1993-03-01

    Conversion of magnetron motion to cyclotron motion combined with collisional cooling of the cyclotron motion provides an efficient way to reduce the kinetic energy of trapped heavy ions and to reduce their magnetron radii in an ion cyclotron resonance (ICR) ion trap. The coupling of magnetron and cyclotron motion can be realized by azimuthal quadrupolar excitation. Theoretical understanding of the coupling process has until now been based on resonant single-frequency quadrupolar excitation at the combination frequency ωc=ω++ω-, in which ωc is the ion cyclotron orbital frequency in the absence of electrostatic field; and ω+ and ω- are the reduced cyclotron and magnetron frequencies in the presence of an electrostatic trapping potential. In this work, we prove that the magnetron/cyclotron coupling is closely related to a two energy level system whose behavior is described by the well-known Bloch equations. By means of a special transformation, the equations of motion for the coupling may be expressed in Bloch-type equations in spherical coordinates. We show that magnetron-to-cyclotron conversion by single-frequency quadrupolar excitation in ICR is analogous to a 180° pulse in nuclear magnetic resonance (NMR). We go on to show that simultaneous magnetron-to-cyclotron conversion of ions over a finite mass-to-charge ratio range may be produced by quadrupolar frequency-sweep excitation, by analogy to adiabatic rapid passage in magnetic resonance. Axialization by broadband magnetron-to-cyclotron conversion followed by cyclotron cooling is successfully demonstrated experimentally for a crude oil distillate sample.

  12. RF priming of a long pulse relativistic magnetron

    NASA Astrophysics Data System (ADS)

    White, William Michael

    Rapid startup, increased pulsewidth and mode locking of magnetrons have been demonstrated experimentally on a relativistic magnetron by radio frequency (RF) priming. Experiments utilize a -300 kV, 2-8 kA, 300-500 ns electron beam to drive a Titan 6-vane relativistic magnetron (˜100 MW output power). The RF priming source is a 100 kW pulsed magnetron operating at 1.27-1.32 GHz. Tuning stubs were utilized in the Titan structure to adjust the operating frequency of the relativistic magnetron pi-mode upward by 30%. The tuning was guided by simulation in the MAGIC 3D code and experimental cold tests including a mapping of the azimuthal electric field inside the relativistic magnetron structure. The most successful tuning geometry was that of a standard anode resonant structure, but RF priming experiments were performed on a rising-sun structure as well. The Time Frequency Analysis (TFA) program was used to directly observe the effects of RF priming on the relativistic magnetron. RF priming was successful in decreasing mode competition by suppressing the generation of the 2pi/3-mode power by 41%. RF priming experiments were also successful in increasing microwave pulsewidth by 12% and decreasing microwave output delay by 22%. These improvements were observed while operating in a priming regime not satisfying Adler's Relation. Overall, the improvements made to the performance of the relativistic magnetron were modest because of the low priming power available (50-250 kW).

  13. An inverted cylindrical sputter magnetron as metal vapor supply for electron cyclotron resonance ion sources.

    PubMed

    Weichsel, T; Hartung, U; Kopte, T; Zschornack, G; Kreller, M; Silze, A

    2014-05-01

    An inverted cylindrical sputter magnetron device has been developed. The magnetron is acting as a metal vapor supply for an electron cyclotron resonance (ECR) ion source. FEM simulation of magnetic flux density was used to ensure that there is no critical interaction between both magnetic fields of magnetron and ECR ion source. Spatially resolved double Langmuir probe and optical emission spectroscopy measurements show an increase in electron density by one order of magnitude from 1 × 10(10) cm(-3) to 1 × 10(11) cm(-3), when the magnetron plasma is exposed to the magnetic mirror field of the ECR ion source. Electron density enhancement is also indicated by magnetron plasma emission photography with a CCD camera. Furthermore, photographs visualize the formation of a localized loss-cone - area, when the magnetron is operated at magnetic mirror field conditions. The inverted cylindrical magnetron supplies a metal atom load rate of R > 1 × 10(18) atoms/s for aluminum, which meets the demand for the production of a milliampere Al(+) ion beam.

  14. Dusty waves and vortices in rf magnetron discharge plasma

    NASA Astrophysics Data System (ADS)

    Filippov, A. V.; Pal, A. F.; Ryabinkin, A. N.; Serov, A. O.; Shugaev, F. V.

    2018-01-01

    The appearance and subsequent growth of metallic particles in plasma of planar rf magnetron sputter were observed. The origin of the particles is sputtering of the rf electrode by ion flux from the plasma. In some regions of formed dust cloud the particles were involved in the horizontal or vertical circular movement. The horizontal rotation along the sputtered track in the cyclotron drift direction was observed close to the main magnetron plasma. The torus-shaped dust vortex ring engirdled the secondary plasma of the discharge at height of a few centimeters over the electrode. Close to this region particle density waves propagated through the cloud. The possible role of discharge plasma azimuthal inhomogeneity and gas dynamics effects in the forming the observed structures was considered.

  15. ION MAGNETRON

    DOEpatents

    Gow, J.D.; Layman, R.W.

    1962-10-31

    A magnetohydrodynamic device or plasma generator of the ion magnetron class is described wherein a long central electrode is disposed along the axis of an evacuated cylinder. A radial electric field and an axial magnetic field are provided between the cylsnder and the electrode, forming a plasma trapping and heating region. For maximum effectiveness, neutral particles from the cylinder wall must be prevented from entering such region This is effected by forming a cylindrical sheath of electrons near the cylinder wall for ionizing undesired neutral particles, which are then trapped and removed by the magnetic field. An annular filament at one end of the device provides the electrons, which follow the axial magnetic field to a reflecting electrode at the opposite end of the device. (AEC)

  16. Simulation and Experimental Studies of a 2.45GHz Magnetron Source for an SRF Cavity with Field Amplitude and Phase Controls

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Haipeng; Plawski, Tomasz E.; Rimmer, Robert A.

    2016-06-01

    Phase lock to an SRF cavity by using injection signal through output waveguide of a magnetron has been demonstrated [1, 3]. Amplitude control using magnetic field trimming and anode voltage modulation has been studied using MATLAB/Simulink simulations [2]. Based on these, we are planning to use an FPGA based digital LLRF system, which allows applying various types of control algorithms in order to achieve the required accelerating field stability. Since the 1497 MHz magnetron is still in the design stage, the proof of principle measurements of a commercial 2450 MHz magnetron are carried out to characterize the anode I-V curve,more » output power (the tube electronic efficiency), frequency dependence on the anode current (frequency pushing) and the Rieke diagram (frequency pulling by the reactive load). Based on early Simulink simulation, experimental data and extension of the Adler equation governing injection phase stability by Chen’s model, the specification of the new LLRF control chassis for both 2450 and 1497MHz systems are presented in this paper.« less

  17. A novel injection-locked amplitude-modulated magnetron at 1497 MHz

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Neubauer, Michael; Wang, Haipeng

    2015-12-15

    Thomas Jefferson National Accelerator Facility (JLab) uses low efficiency klystrons in the CEBAF machine. In the older portion they operate at 30% efficiency with a tube mean time between failure (MTBF) of five to six years. A highly efficient source (>55-60%) must provide a high degree of backwards compatibility, both in size and voltage requirements, to replace the klystron presently used at JLab, while providing energy savings. Muons, Inc. is developing a highly reliable, highly efficient RF source based upon a novel injection-locked amplitude modulated (AM) magnetron with a lower total cost of ownership, >80% efficiency, and MTBF of sixmore » to seven years. The design of the RF source is based upon a single injection-locked magnetron system at 8 kW capable of operating up to 13 kW, using the magnetron magnetic field to achieve the AM required for backwards compatibility to compensate for microphonics and beam loads. A novel injection-locked 1497 MHz 8 kW AM magnetron with a trim magnetic coil was designed and its operation numerically simulated during the Phase I project. The low-level RF system to control the trim field and magnetron anode voltage was designed and modeled for operation at the modulation frequencies of the microphonics. A plan for constructing a prototype magnetron and control system was developed.« less

  18. An inverted cylindrical sputter magnetron as metal vapor supply for electron cyclotron resonance ion sources

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Weichsel, T., E-mail: tim.weichsel@fep.fraunhofer.de; Hartung, U.; Kopte, T.

    2014-05-15

    An inverted cylindrical sputter magnetron device has been developed. The magnetron is acting as a metal vapor supply for an electron cyclotron resonance (ECR) ion source. FEM simulation of magnetic flux density was used to ensure that there is no critical interaction between both magnetic fields of magnetron and ECR ion source. Spatially resolved double Langmuir probe and optical emission spectroscopy measurements show an increase in electron density by one order of magnitude from 1 × 10{sup 10} cm{sup −3} to 1 × 10{sup 11} cm{sup −3}, when the magnetron plasma is exposed to the magnetic mirror field of themore » ECR ion source. Electron density enhancement is also indicated by magnetron plasma emission photography with a CCD camera. Furthermore, photographs visualize the formation of a localized loss-cone - area, when the magnetron is operated at magnetic mirror field conditions. The inverted cylindrical magnetron supplies a metal atom load rate of R > 1 × 10{sup 18} atoms/s for aluminum, which meets the demand for the production of a milliampere Al{sup +} ion beam.« less

  19. Joint quantum measurement using unbalanced array detection.

    PubMed

    Beck, M; Dorrer, C; Walmsley, I A

    2001-12-17

    We have measured the joint Q-function of a highly multimode field using unbalanced heterodyne detection with a charge-coupled device array detector. We use spectral interferometry between a weak signal field and a strong, 100 fs duration local oscillator pulse to reconstruct the joint quadrature amplitude statistics of about 25 temporal modes. By adjusting the time delay between the signal and local oscillator pulses we are able to shift all the classical noise to modes distinct from the signal. This obviates the need to use a balanced detector.

  20. A Compact, Pi-Mode Extraction Scheme for the Axial B-Field Recirculating Planar Magnetron

    DTIC Science & Technology

    2012-07-23

    Figure 4). Thus, in a planar magnetron, the minimum phase velocity, vph , to stay above cutoff in the rectangular waveguide is ℎ = ...as magnetrons, electrons must be accelerated such that they are in synchronism with the phase velocity, vph , of the electromagnetic wave for an

  1. Methods of Phase and Power Control in Magnetron Transmitters for Superconducting Accelerators

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kazadevich, G.; Johnson, R.; Neubauer, M.

    Various methods of phase and power control in magnetron RF sources of superconducting accelerators intended for ADS-class projects were recently developed and studied with conventional 2.45 GHz, 1 kW, CW magnetrons operating in pulsed and CW regimes. Magnetron transmitters excited by a resonant (injection-locking) phasemodulated signal can provide phase and power control with the rates required for precise stabilization of phase and amplitude of the accelerating field in Superconducting RF (SRF) cavities of the intensity-frontier accelerators. An innovative technique that can significantly increase the magnetron transmitter efficiency at the widerange power control required for superconducting accelerators was developed and verifiedmore » with the 2.45 GHz magnetrons operating in CW and pulsed regimes. High efficiency magnetron transmitters of this type can significantly reduce the capital and operation costs of the ADSclass accelerator projects.« less

  2. NOVEL TECHNIQUE OF POWER CONTROL IN MAGNETRON TRANSMITTERS FOR INTENSE ACCELERATORS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kazakevich, G.; Johnson, R.; Neubauer, M.

    A novel concept of a high-power magnetron transmitter allowing dynamic phase and power control at the frequency of locking signal is proposed. The transmitter compensating parasitic phase and amplitude modulations inherent in Superconducting RF (SRF) cavities within closed feedback loops is intended for powering of the intensity-frontier superconducting accelerators. The con- cept uses magnetrons driven by a sufficient resonant (in- jection-locking) signal and fed by the voltage which can be below the threshold of self-excitation. This provides an extended range of power control in a single magnetron at highest efficiency minimizing the cost of RF power unit and the operationmore » cost. Proof-of-principle of the proposed concept demonstrated in pulsed and CW regimes with 2.45 GHz, 1kW magnetrons is discussed here. A conceptual scheme of the high-power transmitter allowing the dynamic wide-band phase and y power controls is presented and discussed.« less

  3. Neutral gas rotation in magnetron discharge

    NASA Astrophysics Data System (ADS)

    Pal, A. F.; Ryabinkin, A. N.; Serov, A. O.; Filippov, A. V.

    2014-12-01

    We have experimentally established the existence and determined the velocity of motion of the neutral component of plasma in a planar magnetron discharge, which takes place in the direction of drift of the charged plasma component in crossed electric and magnetic ( E × B) fields. For this purpose, we have studied the propagation of a small gaseous additive over the plasma ring of dc magnetron discharge in the diffusion regime. The obtained temporal dependences of the intensity of atomic emission spectra of the additive in various regions of the plasma ring are compared to the results of numerical solution of the diffusion equation for the experimental conditions studied.

  4. Effect of assistant rf field on phase composition of iron nitride film prepared by magnetron sputtering process

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Li, W.L.; Zheng, F.; Fei, W.D.

    2006-01-15

    Fe-N thin films were fabricated using a direct current magnetron sputtering process assisted by a radio-frequency (rf) field. The effect of the rf field on the phase composition of the films was investigated. The results indicate that with the assistance of the rf field, various kinds of iron nitrides can be obtained in the films, including {alpha}{sup '}-Fe-N, {alpha}{sup ''}-Fe{sub 16}N{sub 2}, {xi}-Fe{sub 2}N, {epsilon}-Fe{sub 3}N, and {gamma}{sup ''}-FeN with ZnS structure. It was found that the rf field greatly benefits the formation of iron nitrides in the Fe-N films.

  5. Field emission from ZnS nanorods synthesized by radio frequency magnetron sputtering technique

    NASA Astrophysics Data System (ADS)

    Ghosh, P. K.; Maiti, U. N.; Jana, S.; Chattopadhyay, K. K.

    2006-11-01

    The field emission property of zinc sulphides nanorods synthesized in the thin film form on Si substrates has been studied. It is seen that ZnS nanorod thin films showed good field emission properties with a low-macroscopic turn-on field (2.9-6.3 V/μm). ZnS nanorods were synthesized by using radio frequency magnetron sputtering of a polycrystalline prefabricated ZnS target at a relatively higher pressure (10 -1 mbar) and at a lower substrate temperature (233-273 K) without using any catalyst. Transmission electron microscopic image showed the formation of ZnS nanorods with high aspect ratio (>60). The field emission data were analysed using Fowler-Nordhiem theory and the nearly straight-line nature of the F-N plots confirmed cold field emission of electrons. It was also found that the turn-on field decreased with the decrease of nanorod's diameters. The optical properties of the ZnS nanorods were also studied. From the measurements of transmittance of the films deposited on glass substrates, the direct allowed bandgap values have been calculated and they were in the range 3.83-4.03 eV. The thickness of the films was ˜600 nm.

  6. Novel high power impulse magnetron sputtering enhanced by an auxiliary electrical field

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Li, Chunwei, E-mail: lcwnefu@126.com, E-mail: xiubotian@163.com; State Key Laboratory of Advanced Welding and Joining, Harbin Institute of Technology, Harbin 150001; Tian, Xiubo, E-mail: lcwnefu@126.com, E-mail: xiubotian@163.com

    2016-08-15

    The high power impulse magnetron sputtering (HIPIMS) technique is a novel highly ionized physical vapor deposition method with a high application potential. However, the electron utilization efficiency during sputtering is rather low and the metal particle ionization rate needs to be considerably improved to allow for a large-scale industrial application. Therefore, we enhanced the HIPIMS technique by simultaneously applying an electric field (EF-HIPIMS). The effect of the electric field on the discharge process was studied using a current sensor and an optical emission spectrometer. Furthermore, the spatial distribution of the electric potential and electric field during the EF-HIPIMS process wasmore » simulated using the ANSYS software. The results indicate that a higher electron utilization efficiency and a higher particle ionization rate could be achieved. The auxiliary anode obviously changed the distribution of the electric potential and the electric field in the discharge region, which increased the plasma density and enhanced the degree of ionization of the vanadium and argon gas. Vanadium films were deposited to further compare both techniques, and the morphology of the prepared films was investigated by scanning electron microscopy. The films showed a smaller crystal grain size and a denser growth structure when the electric field was applied during the discharge process.« less

  7. Power Analysis in Two-Level Unbalanced Designs

    ERIC Educational Resources Information Center

    Konstantopoulos, Spyros

    2010-01-01

    Previous work on statistical power has discussed mainly single-level designs or 2-level balanced designs with random effects. Although balanced experiments are common, in practice balance cannot always be achieved. Work on class size is one example of unbalanced designs. This study provides methods for power analysis in 2-level unbalanced designs…

  8. Measurement Of Hydrogen Capacities And Stability In Thin Films Of AlH Deposited By Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    Dissanayake, A.; AlFaify, S.; Garratt, E.; Nandasiri, M. I.; Taibu, R.; Tecos, G.; Hamdan, N. M.; Kayani, A.

    2011-06-01

    Thin, hydrogenated aluminum hydride films were deposited on silicon substrates using unbalanced magnetron (UBM) sputtering of a high purity aluminum target under electrically grounded conditions. Argon was used as sputtering gas and hydrogenation was carried out by diluting the growth plasma with hydrogen. The effect of hydrogen partial pressure on the final concentration of trapped elements including hydrogen has been studied using ion beam analysis (IBA) techniques. Moreover, in-situ thermal stability of trapped hydrogen in the film was carried out using Rutherford Backscattering Spectrometry (RBS), Non-Rutherford Backscattering Spectrometry (NRBS) and Elastic Recoil Detection Analysis (ERDA). Microstructure of the film was investigated by SEM analysis. Hydrogen content in the thin films was found decreasing as the films were heated above 110 °C in vacuum.

  9. Modulated electron cyclotron drift instability in a high-power pulsed magnetron discharge.

    PubMed

    Tsikata, Sedina; Minea, Tiberiu

    2015-05-08

    The electron cyclotron drift instability, implicated in electron heating and anomalous transport, is detected in the plasma of a planar magnetron. Electron density fluctuations associated with the mode are identified via an adapted coherent Thomson scattering diagnostic, under direct current and high-power pulsed magnetron operation. Time-resolved analysis of the mode amplitude reveals that the instability, found at MHz frequencies and millimeter scales, also exhibits a kHz-scale modulation consistent with the observation of larger-scale plasma density nonuniformities, such as the rotating spoke. Sharply collimated axial fluctuations observed at the magnetron axis are consistent with the presence of escaping electrons in a region where the magnetic and electric fields are antiparallel. These results distinguish aspects of magnetron physics from other plasma sources of similar geometry, such as the Hall thruster, and broaden the scope of instabilities which may be considered to dictate magnetron plasma features.

  10. Theoretical investigation of resonant frequencies of unstrapped magnetron with arbitrary side resonators

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yue, Song, E-mail: yuessd@163.com; University of Chinese Academy of Sciences, Beijing 100049; Zhang, Zhao-chuan

    In this paper, a sector steps approximation method is proposed to investigate the resonant frequencies of magnetrons with arbitrary side resonators. The arbitrary side resonator is substituted with a series of sector steps, in which the spatial harmonics of electromagnetic field are also considered. By using the method of admittance matching between adjacent steps, as well as field continuity conditions between side resonators and interaction regions, the dispersion equation of magnetron with arbitrary side resonators is derived. Resonant frequencies of magnetrons with five common kinds of side resonators are calculated with sector steps approximation method and computer simulation softwares, inmore » which the results have a good agreement. The relative error is less than 2%, which verifies the validity of sector steps approximation method.« less

  11. Initiation of a Relativistic Magnetron

    NASA Astrophysics Data System (ADS)

    Kaup, D. J.

    2003-10-01

    We report on recent results in our studies of relativistic magnetrons. Experimentally, these devices have proven to be very difficult to operate, typically cutting off too quickly after they are initialized, and therefore not delivering the power levels expected [1]. Our analysis is based on our model of a crossed-field device, consisting only of its two dominant modes, a DC background and an RF oscillating mode [2]. This approach has produced generally quantitatively correct values for the operating regime and major features of nonrelativistic devices. We have performed a fully electromagnetic, relativistic analysis of a magnetron of the A6 cylindrical configuration. We will show that when the device should generate maximum power, it enters a regime where the DC background could become potentially unstable. In particular, when a nonrelativistic planar device enters the saturation regime, the DC electron density distribution could become unstable if the vertical DC velocity would ever become equal to the magnitude of the vertical RF velocity [3]. We find that during the initiation phase, for the highest power levels of our model of the A6, near the cathode, the DC vertical velocity does become just less than, and definitely on the order of the magnitude of the vertical RF velocity. Consequently, any localized surge in the currents near the cathode, could easily destroy the smooth upward flow of the electrons, drive the DC background unstable, and thereby shut down the operation of the device. [1] Long-pulse relativistic magnetron experiments, M.R. Lopez, R.M. Gilgenbach, Y.Y. Lau, D.W. Jordan, M.D. Johnston, M.C. Jones, V.B. Neculaes, T.A. Spencer, J.W. Luginsland, M.D. Haworth, R.W.Lemke, D. Price, and L. Ludeking, Proc. of SPIE Aerosense 4720, 10-17, (2002). [2] Theoretical modeling of crossed-field electron vacuum devices, D.J. Kaup, Phys. of Plasmas 8, 2473-80 (2001). [3] Initiation and Stationary Operating States in a Crossed-Field Vacuum Electron Device, D. J

  12. An efficient magnetron transmitter for superconducting accelerators

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kazakevich, G.; Lebedev, V.; Yakovlev, V.

    A concept of a highly-efficient high-power magnetron transmitter allowing wide-band phase and the mid-frequency power control at the frequency of the locking signal is proposed. The proposal is aimed for powering Superconducting RF (SRF) cavities of intensity-frontier accelerators. The transmitter is intended to operate with phase and amplitude control feedback loops allowing suppression of microphonics and beam loading in the SRF cavities. The concept utilizes injectionlocked magnetrons controlled in phase by the locking signal supplied by a feedback system. The injection-locking signal pre-excites the magnetron and allows its operation below the critical voltage. This realizes control of the magnetron powermore » in a wide range by control of the magnetron current. Pre-excitation of the magnetron by the locking signal provides an output power range up to 10 dB. Experimental studies were carried out with 2.45 GHz, 1 kW, CW magnetrons. They demonstrated stable operation of the magnetrons and power control at a low noise level. In conclusion, an analysis of the kinetics of the drifting charge in the drift approximation substantiates the concept and the experimental results.« less

  13. An efficient magnetron transmitter for superconducting accelerators

    DOE PAGES

    Kazakevich, G.; Lebedev, V.; Yakovlev, V.; ...

    2016-09-22

    A concept of a highly-efficient high-power magnetron transmitter allowing wide-band phase and the mid-frequency power control at the frequency of the locking signal is proposed. The proposal is aimed for powering Superconducting RF (SRF) cavities of intensity-frontier accelerators. The transmitter is intended to operate with phase and amplitude control feedback loops allowing suppression of microphonics and beam loading in the SRF cavities. The concept utilizes injectionlocked magnetrons controlled in phase by the locking signal supplied by a feedback system. The injection-locking signal pre-excites the magnetron and allows its operation below the critical voltage. This realizes control of the magnetron powermore » in a wide range by control of the magnetron current. Pre-excitation of the magnetron by the locking signal provides an output power range up to 10 dB. Experimental studies were carried out with 2.45 GHz, 1 kW, CW magnetrons. They demonstrated stable operation of the magnetrons and power control at a low noise level. In conclusion, an analysis of the kinetics of the drifting charge in the drift approximation substantiates the concept and the experimental results.« less

  14. Magnetron sputtering source

    DOEpatents

    Makowiecki, Daniel M.; McKernan, Mark A.; Grabner, R. Fred; Ramsey, Philip B.

    1994-01-01

    A magnetron sputtering source for sputtering coating substrates includes a high thermal conductivity electrically insulating ceramic and magnetically attached sputter target which can eliminate vacuum sealing and direct fluid cooling of the cathode assembly. The magnetron sputtering source design results in greater compactness, improved operating characteristics, greater versatility, and low fabrication cost. The design easily retrofits most sputtering apparatuses and provides for safe, easy, and cost effective target replacement, installation, and removal.

  15. Magnetron sputtering source

    DOEpatents

    Makowiecki, D.M.; McKernan, M.A.; Grabner, R.F.; Ramsey, P.B.

    1994-08-02

    A magnetron sputtering source for sputtering coating substrates includes a high thermal conductivity electrically insulating ceramic and magnetically attached sputter target which can eliminate vacuum sealing and direct fluid cooling of the cathode assembly. The magnetron sputtering source design results in greater compactness, improved operating characteristics, greater versatility, and low fabrication cost. The design easily retrofits most sputtering apparatuses and provides for safe, easy, and cost effective target replacement, installation, and removal. 12 figs.

  16. Detection of gain enhancement in laser-induced fluorescence of rhodamine B lasing dye by silicon dioxide nanostructures-coated cavity

    NASA Astrophysics Data System (ADS)

    Al-Tameemi, Mohammed N. A.

    2018-03-01

    In this work, nanostructured silicon dioxide films are deposited by closed-field unbalanced direct-current (DC) reactive magnetron sputtering technique on two sides of quartz cells containing rhodamine B dye dissolved in ethanol with 10‒5 M concentration as a random gain medium. The preparation conditions are optimized to prepare highly pure SiO2 nanostructures with a minimum particle size of about 20 nm. The effect of SiO2 films as external cavity for the random gain medium is determined by the laser-induced fluorescence of this medium, and an increase of about 200% in intensity is observed after the deposition of nanostructured SiO2 thin films on two sides of the dye cell.

  17. Particle-In-Cell (PIC) simulation of long-anode magnetron

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Verma, Rajendra Kumar, E-mail: rajendra.verma89@gmail.com; Maurya, Shivendra; Singh, Vindhyavasini Prasad

    Long Anode Magnetron (LAM) is a design scheme adopted to attain greater thermal stability and higher power levels for the conventional magnetrons. So a LAM for 5MW Power level at 2.858 GHz was ‘Virtual Prototyped’ using Admittance Matching field theory (AMT) andthen a PIC Study (Beam-wave interaction) was conducted using CST Particle Studio (CST-PS) which is explained in this paper. The convincing results thus obtained were – hot resonant frequency of 2.834 GHz. Output power of 5 MW at beam voltage of 58kV and applied magnetic field of 2200 Gauss with an overall efficiency of 45%. The simulated parameters values on comparisonmore » with the E2V LAM tube (M5028) were in good agreement which validates the feasibility of the design approach.« less

  18. A Three-Phase Microgrid Restoration Model Considering Unbalanced Operation of Distributed Generation

    DOE PAGES

    Wang, Zeyu; Wang, Jianhui; Chen, Chen

    2016-12-07

    Recent severe outages highlight the urgency of improving grid resiliency in the U.S. Microgrid formation schemes are proposed to restore critical loads after outages occur. Most distribution networks have unbalanced configurations that are not represented in sufficient detail by single-phase models. This study provides a microgrid formation plan that adopts a three-phase network model to represent unbalanced distribution networks. The problem formulation has a quadratic objective function with mixed-integer linear constraints. The three-phase network model enables us to examine the three-phase power outputs of distributed generators (DGs), preventing unbalanced operation that might trip DGs. Because the DG unbalanced operation constraintmore » is non-convex, an iterative process is presented that checks whether the unbalanced operation limits for DGs are satisfied after each iteration of optimization. We also develop a relatively conservative linear approximation on the unbalanced operation constraint to handle larger networks. Compared with the iterative solution process, the conservative linear approximation is able to accelerate the solution process at the cost of sacrificing optimality to a limited extent. Simulation in the IEEE 34 node and IEEE 123 test feeders indicate that the proposed method yields more practical microgrid formations results. In addition, this paper explores the coordinated operation of DGs and energy storage (ES) installations. The unbalanced three-phase outputs of ESs combined with the relatively balanced outputs of DGs could supply unbalanced loads. In conclusion, the case study also validates the DG-ES coordination.« less

  19. A Three-Phase Microgrid Restoration Model Considering Unbalanced Operation of Distributed Generation

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wang, Zeyu; Wang, Jianhui; Chen, Chen

    Recent severe outages highlight the urgency of improving grid resiliency in the U.S. Microgrid formation schemes are proposed to restore critical loads after outages occur. Most distribution networks have unbalanced configurations that are not represented in sufficient detail by single-phase models. This study provides a microgrid formation plan that adopts a three-phase network model to represent unbalanced distribution networks. The problem formulation has a quadratic objective function with mixed-integer linear constraints. The three-phase network model enables us to examine the three-phase power outputs of distributed generators (DGs), preventing unbalanced operation that might trip DGs. Because the DG unbalanced operation constraintmore » is non-convex, an iterative process is presented that checks whether the unbalanced operation limits for DGs are satisfied after each iteration of optimization. We also develop a relatively conservative linear approximation on the unbalanced operation constraint to handle larger networks. Compared with the iterative solution process, the conservative linear approximation is able to accelerate the solution process at the cost of sacrificing optimality to a limited extent. Simulation in the IEEE 34 node and IEEE 123 test feeders indicate that the proposed method yields more practical microgrid formations results. In addition, this paper explores the coordinated operation of DGs and energy storage (ES) installations. The unbalanced three-phase outputs of ESs combined with the relatively balanced outputs of DGs could supply unbalanced loads. In conclusion, the case study also validates the DG-ES coordination.« less

  20. Unbalanced atrioventricular septal defect: definition and decision making.

    PubMed

    Overman, David M; Baffa, Jeanne M; Cohen, Meryl S; Mertens, Luc; Gremmels, David B; Jegatheeswaram, Anusha; McCrindle, Brian W; Blackstone, Eugene H; Morell, Victor O; Caldarone, Christopher; Williams, William G; Pizarro, Christian

    2010-04-01

    Unbalanced atrioventricular septal defect is an uncommon lesion with widely varying anatomic manifestations. When unbalance is severe, diagnosis and treatment is straightforward, directed toward single-ventricle palliation. Milder forms, however, pose a challenge to current diagnostic and therapeutic approaches. The transition from anatomies that are capable of sustaining biventricular physiology to those that cannot is obscure, resulting in uneven application of surgical strategy and excess mortality. Imprecise assessments of ventricular competence have dominated clinical decision making in this regard. Malalignment of the atrioventricular junction and its attendant derangement of inflow physiology is a critical factor in determining the feasibility of biventricular repair in the setting of unbalanced atrioventricular septal defect. The atrioventricular valve index accurately identifies unbalanced atrioventricular septal defect and also brings into focus a zone of transition from anatomies that can support a biventricular end state and those that cannot.

  1. ZrN coatings deposited by high power impulse magnetron sputtering and cathodic arc techniques

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Purandare, Yashodhan, E-mail: Y.Purandare@shu.ac.uk; Ehiasarian, Arutiun; Hovsepian, Papken

    Zirconium nitride (ZrN) coatings were deposited on 1 μm finish high speed steel and 316L stainless steel test coupons. Cathodic Arc (CA) and High Power Impulse Magnetron Sputtering (HIPIMS) + Unbalanced Magnetron Sputtering (UBM) techniques were utilized to deposit coatings. CA plasmas are known to be rich in metal and gas ions of the depositing species as well as macroparticles (droplets) emitted from the arc sports. Combining HIPIMS technique with UBM in the same deposition process facilitated increased ion bombardment on the depositing species during coating growth maintaining high deposition rate. Prior to coating deposition, substrates were pretreated with Zr{sup +}more » rich plasma, for both arc deposited and HIPIMS deposited coatings, which led to a very high scratch adhesion value (L{sub C2}) of 100 N. Characterization results revealed the overall thickness of the coatings in the range of 2.5 μm with hardness in the range of 30–40 GPa depending on the deposition technique. Cross-sectional transmission electron microscopy and tribological experiments such as dry sliding wear tests and corrosion studies have been utilized to study the effects of ion bombardment on the structure and properties of these coatings. In all the cases, HIPIMS assisted UBM deposited coating fared equal or better than the arc deposited coatings, the reasons being discussed in this paper. Thus H+U coatings provide a good alternative to arc deposited where smooth, dense coatings are required and macrodroplets cannot be tolerated.« less

  2. Magnetron Electron Gun,

    DTIC Science & Technology

    1980-05-23

    ULMAGNETRON ELECTRON GUN . (U) .Ay G0 A L GOLOENBERG, T B PANKRATOVA UNCLASSIFIED FTD..In(RS)T41896-?9 4 __ ihD - -111113 MICROCOPY RESOLUTION TEST...CHART NATIONAL BUREAU OF STANDARD 1961 A -_"D-I-D ,RS)T-18q6-79 v FOREIGN TECHNOLOGY DIVISION MAGNETRON ELECTRON GUN by A. L. Gol’denberg, T. B...VISION. WP.AP6. OHIO. FTD -ID(RS)T-1396-79 Date z.-.:a’,-lq -,o • 110ewm /A Is a, -D r.l MAGNETRON ELECTRON GUN A. L. Gol’denberg, T. B. Pankratova and M

  3. Structure evolution of zinc oxide thin films deposited by unbalance DC magnetron sputtering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Aryanto, Didik, E-mail: didi027@lipi.go.id; Materials Research Group, Physics Department, Universitas Negeri Semarang, Gunungpati, Semarang 50229 Jawa Tengah; Marwoto, Putut

    Zinc oxide (ZnO) thin films are deposited on corning glass substrates using unbalanced DC magnetron sputtering. The effect of growth temperature on surface morphology and crystallographic orientation of ZnO thin film is studied using atomic force microscopy (AFM) and X-ray diffraction (XRD) techniques. The surface morphology and crystallographic orientation of ZnO thin film are transformed against the increasing of growth temperature. The mean grain size of film and the surface roughness are inversely and directly proportional towards the growth temperature from room temperature to 300 °C, respectively. The smaller grain size and finer roughness of ZnO thin film are obtainedmore » at growth temperature of 400 °C. The result of AFM analysis is in good agreement with the result of XRD analysis. ZnO thin films deposited in a series of growth temperatures have hexagonal wurtzite polycrystalline structures and they exhibit transformations in the crystallographic orientation. The results in this study reveal that the growth temperature strongly influences the surface morphology and crystallographic orientation of ZnO thin film.« less

  4. Rapid start of oscillations in a magnetron with a "transparent" cathode.

    PubMed

    Fuks, Mikhail; Schamiloglu, Edl

    2005-11-11

    We report on the improvement of conditions for the rapid start of oscillations in magnetrons by increasing the amplitude of the operating wave that is responsible for the capture of electrons into spokes. This amplitude increase is achieved by using a hollow cathode with longitudinal strips removed, thereby making the cathode transparent to the wave electric field with azimuthal polarization. In addition, an optimal choice of the number and position of cathode strips provide favorable prebunching of the electron flow over the cathode for fast excitation of the operating mode. Particle-in-cell simulations of the A6 magnetron demonstrate these advantages of this novel cathode.

  5. Fracture toughness and sliding properties of magnetron sputtered CrBC and CrBCN coatings

    NASA Astrophysics Data System (ADS)

    Wang, Qianzhi; Zhou, Fei; Ma, Qiang; Callisti, Mauro; Polcar, Tomas; Yan, Jiwang

    2018-06-01

    CrBC and CrBCN coatings with low and high B contents were deposited on 316L steel and Si wafers using an unbalanced magnetron sputtering system. Mechanical properties including hardness (H), elastic modulus (E) and fracture toughness (KIc) as well as residual stresses (σ) were quantified. A clear correlation between structural, mechanical and tribological properties of coatings was found. In particular, structural analyses indicated that N incorporation in CrBC coatings with high B content caused a significant structural evolution of the nanocomposite structure (crystalline grains embedded into an amorphous matrix) from nc-CrB2/(a-CrBx, a-BCx) to nc-CrN/(a-BCx, a-BN). As a result, the hardness of CrBC coating with high B content decreased from 23.4 to 16.3 GPa but the fracture toughness was enhanced. Consequently, less cracks initiated on CrBCN coatings during tribological tests, which combined with the shielding effect of a-BN on wear debris, led to a low friction coefficient and wear rate.

  6. Real-space observation of unbalanced charge distribution inside a perovskite-sensitized solar cell.

    PubMed

    Bergmann, Victor W; Weber, Stefan A L; Javier Ramos, F; Nazeeruddin, Mohammad Khaja; Grätzel, Michael; Li, Dan; Domanski, Anna L; Lieberwirth, Ingo; Ahmad, Shahzada; Berger, Rüdiger

    2014-09-22

    Perovskite-sensitized solar cells have reached power conversion efficiencies comparable to commercially available solar cells used for example in solar farms. In contrast to silicon solar cells, perovskite-sensitized solar cells can be made by solution processes from inexpensive materials. The power conversion efficiency of these cells depends substantially on the charge transfer at interfaces. Here we use Kelvin probe force microscopy to study the real-space cross-sectional distribution of the internal potential within high efficiency mesoscopic methylammonium lead tri-iodide solar cells. We show that the electric field is homogeneous through these devices, similar to that of a p-i-n type junction. On illumination under short-circuit conditions, holes accumulate in front of the hole-transport layer as a consequence of unbalanced charge transport in the device. After light illumination, we find that trapped charges remain inside the active device layers. Removing these traps and the unbalanced charge injection could enable further improvements in performance of perovskite-sensitized solar cells.

  7. Microwave impedance matching strategies of an applicator supplied by a bi-directional magnetron waveguide launcher.

    PubMed

    Roussy, Georges; Kongmark, Nils

    2003-01-01

    It is shown that a bi-directional waveguide launcher can be used advantageously for reducing the reflection coefficient mismatch of an input impedance of an applicator. In a simple bi-directional waveguide launcher, the magnetron is placed in the waveguide and generates a nominal field distribution with significant output impedance in both directions of the waveguide. If a standing wave is tolerated in the torus, which connects the launcher and the applicator, the power transfer from the magnetron to the applicator can be optimal, without using special matching devices. It is also possible to match the bi-directional launcher with two inductance stubs near the antenna of the magnetron and use them for supplying a two-input applicator without reflection.

  8. Particle-in-Cell Modeling of Magnetron Sputtering Devices

    NASA Astrophysics Data System (ADS)

    Cary, John R.; Jenkins, T. G.; Crossette, N.; Stoltz, Peter H.; McGugan, J. M.

    2017-10-01

    In magnetron sputtering devices, ions arising from the interaction of magnetically trapped electrons with neutral background gas are accelerated via a negative voltage bias to strike a target cathode. Neutral atoms ejected from the target by such collisions then condense on neighboring material surfaces to form a thin coating of target material; a variety of industrial applications which require thin surface coatings are enabled by this plasma vapor deposition technique. In this poster we discuss efforts to simulate various magnetron sputtering devices using the Vorpal PIC code in 2D axisymmetric cylindrical geometry. Field solves are fully self-consistent, and discrete models for sputtering, secondary electron emission, and Monte Carlo collisions are included in the simulations. In addition, the simulated device can be coupled to an external feedback circuit. Erosion/deposition profiles and steady-state plasma parameters are obtained, and modifications due to self consistency are seen. Computational performance issues are also discussed. and Tech-X Corporation.

  9. Magnetron sputtering for the production of EUV mask blanks

    NASA Astrophysics Data System (ADS)

    Kearney, Patrick; Ngai, Tat; Karumuri, Anil; Yum, Jung; Lee, Hojune; Gilmer, David; Vo, Tuan; Goodwin, Frank

    2015-03-01

    Ion Beam Deposition (IBD) has been the primary technique used to deposit EUV mask blanks since 1995 when it was discovered it could produce multilayers with few defects. Since that time the IBD technique has been extensively studied and improved and is finally approaching usable defectivities. But in the intervening years, the defectivity of magnetron sputtering has been greatly improved. This paper evaluates the suitability of a modern magnetron tool to produce EUV mask blanks and the ability to support HVM production. In particular we show that the reflectivity and uniformity of these tools are superior to current generation IBD tools, and that the magnetron tools can produce EUV films with defect densities comparable to recent best IBD tool performance. Magnetron tools also offer many advantages in manufacturability and tool throughput; however, challenges remain, including transitioning the magnetron tools from the wafer to mask formats. While work continues on quantifying the capability of magnetron sputtering to meet the mask blank demands of the industry, for the most part the remaining challenges do not require any fundamental improvements to existing technology. Based on the recent results and the data presented in this paper there is a clear indication that magnetron deposition should be considered for the future of EUV mask blank production.

  10. Phenotypic Signatures Arising from Unbalanced Bacterial Growth

    PubMed Central

    Tan, Cheemeng; Smith, Robert Phillip; Tsai, Ming-Chi; Schwartz, Russell; You, Lingchong

    2014-01-01

    Fluctuations in the growth rate of a bacterial culture during unbalanced growth are generally considered undesirable in quantitative studies of bacterial physiology. Under well-controlled experimental conditions, however, these fluctuations are not random but instead reflect the interplay between intra-cellular networks underlying bacterial growth and the growth environment. Therefore, these fluctuations could be considered quantitative phenotypes of the bacteria under a specific growth condition. Here, we present a method to identify “phenotypic signatures” by time-frequency analysis of unbalanced growth curves measured with high temporal resolution. The signatures are then applied to differentiate amongst different bacterial strains or the same strain under different growth conditions, and to identify the essential architecture of the gene network underlying the observed growth dynamics. Our method has implications for both basic understanding of bacterial physiology and for the classification of bacterial strains. PMID:25101949

  11. Phenotypic signatures arising from unbalanced bacterial growth.

    PubMed

    Tan, Cheemeng; Smith, Robert Phillip; Tsai, Ming-Chi; Schwartz, Russell; You, Lingchong

    2014-08-01

    Fluctuations in the growth rate of a bacterial culture during unbalanced growth are generally considered undesirable in quantitative studies of bacterial physiology. Under well-controlled experimental conditions, however, these fluctuations are not random but instead reflect the interplay between intra-cellular networks underlying bacterial growth and the growth environment. Therefore, these fluctuations could be considered quantitative phenotypes of the bacteria under a specific growth condition. Here, we present a method to identify "phenotypic signatures" by time-frequency analysis of unbalanced growth curves measured with high temporal resolution. The signatures are then applied to differentiate amongst different bacterial strains or the same strain under different growth conditions, and to identify the essential architecture of the gene network underlying the observed growth dynamics. Our method has implications for both basic understanding of bacterial physiology and for the classification of bacterial strains.

  12. Serially-Connected Compensator for Eliminating the Unbalanced Three-Phase Voltage Impact on Wind Turbine Generators: Preprint

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wu, Z.; Hsu, P.; Muljadi, E.

    2015-04-06

    Untransposed transmission lines, unbalanced tap changer operations, and unbalanced loading in weak distribution lines can cause unbalanced-voltage conditions. The resulting unbalanced voltage at the point of interconnection affects proper gird integration and reduces the lifetime of wind turbines due to power oscillations, torque pulsations, mechanical stresses, energy losses, and uneven and overheating of the generator stator winding. This work investigates the dynamic impact of unbalanced voltage on the mechanical and electrical components of integrated Fatigue, Aerodynamics, Structures, and Turbulence (FAST) wind turbine generation systems (WTGs) of Type 1 (squirrel-cage induction generator) and Type 3 (doubly-fed induction generator). To alleviate thismore » impact, a serially-connected compensator for a three-phase power line is proposed to balance the wind turbine-side voltage. Dynamic simulation studies are conducted in MATLAB/Simulink to compare the responses of these two types of wind turbine models under normal and unbalanced-voltage operation conditions and demonstrate the effectiveness of the proposed compensator.« less

  13. A Serially-Connected Compensator for Eliminating the Unbalanced Three-Phase Voltage Impact on Wind Turbine Generators

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wu, Ziping; Hsu, Ping; Muljadi, Eduard

    2015-10-05

    Untransposed transmission lines, unbalanced tap changer operations, and unbalanced loading in weak distribution lines can cause unbalanced-voltage conditions. The resulting unbalanced voltage at the point of interconnection affects proper gird integration and reduces the lifetime of wind turbines due to power oscillations, torque pulsations, mechanical stresses, energy losses, and uneven and overheating of the generator stator winding. This work investigates the dynamic impact of unbalanced voltage on the mechanical and electrical components of integrated Fatigue, Aerodynamics, Structures, and Turbulence (FAST) wind turbine generation systems (WTGs) of Type 1 (squirrel-cage induction generator) and Type 3 (doubly-fed induction generator). To alleviate thismore » impact, a serially-connected compensator for a three-phase power line is proposed to balance the wind turbine-side voltage. Dynamic simulation studies are conducted in MATLAB/Simulink to compare the responses of these two types of wind turbine models under normal and unbalanced-voltage operation conditions and demonstrate the effectiveness of the proposed compensator.« less

  14. Cathode Priming vs. RF Priming for Relativistic Magnetrons

    NASA Astrophysics Data System (ADS)

    White, W. M.; Spencer, T. A.; Price, D.

    2005-10-01

    Magnetron start-oscillation time, pulsewidth and pi-mode locking are experimentally compared for RF priming versus cathode priming on the Michigan-Titan relativistic magnetron (-300 kV, 2-10 kA, 300-500 ns). Cathode priming [1, 2] is an innovative technique first demonstrated experimentally at UM. In this technique, the cathode is fabricated with N/2 emitting strips or N/2-separate cathodes (for an N-cavity magnetron), which generate the desired number of spokes for pi-mode. Cathode priming yields 13% faster startup with more reproducible pi-mode oscillation. Radio Frequency (RF) priming is investigated as the baseline priming technique for magnetrons. The external priming source is a 100kW, 3μs pulsewidth magnetron on loan from AFRL. RF priming reduced startup delay by 15% and increased pulsewidth by 9%. [1] M.C. Jones, V.B. Neculaes, R.M. Gilgenbach, W.M. White, M.R. Lopez, Y.Y. Lau, T.A. Spencer, and D. Price, Rev. Sci. Inst., 75, 2976 (2004) [2] M.C. Jones, Doctoral Dissertation, University of Michigan, 2005

  15. Spoke rotation reversal in magnetron discharges of aluminium, chromium and titanium

    NASA Astrophysics Data System (ADS)

    Hecimovic, A.; Maszl, C.; Schulz-von der Gathen, V.; Böke, M.; von Keudell, A.

    2016-06-01

    The rotation of localised ionisation zones, i.e. spokes, in magnetron discharge are frequently observed. The spokes are investigated by measuring floating potential oscillations with 12 flat probes placed azimuthally around a planar circular magnetron. The 12-probe setup provides sufficient temporal and spatial resolution to observe the properties of various spokes, such as rotation direction, mode number and angular velocity. The spokes are investigated as a function of discharge current, ranging from 10 mA (current density 0.5 mA cm-2) to 140 A (7 A cm-2). In the range from 10 mA to 600 mA the plasma was sustained in DC mode, and in the range from 1 A to 140 A the plasma was pulsed in high-power impulse magnetron sputtering mode. The presence of spokes throughout the complete discharge current range indicates that the spokes are an intrinsic property of a magnetron sputtering plasma discharge. The spokes may disappear at discharge currents above 80 A for Cr, as the plasma becomes homogeneously distributed over the racetrack. Up to discharge currents of several amperes (the exact value depends on the target material), the spokes rotate in a retrograde \\mathbf{E}× \\mathbf{B} direction with angular velocity in the range of 0.2-4 km s-1. Beyond a discharge current of several amperes, the spokes rotate in a \\mathbf{E}× \\mathbf{B} direction with angular velocity in the range of 5-15 km s-1. The spoke rotation reversal is explained by a transition from Ar-dominated to metal-dominated sputtering that shifts the plasma emission zone closer to the target. The spoke itself corresponds to a region of high electron density and therefore to a hump in the electrical potential. The electric field around the spoke dominates the spoke rotation direction. At low power, the plasma is further away from the target and it is dominated by the electric field to the anode, thus retrograde \\mathbf{E}× \\mathbf{B} rotation. At high power, the plasma is closer to the target and it is

  16. Modeling and experimental studies of a side band power re-injection locked magnetron

    NASA Astrophysics Data System (ADS)

    Ye, Wen-Jun; Zhang, Yi; Yuan, Ping; Zhu, Hua-Cheng; Huang, Ka-Ma; Yang, Yang

    2016-12-01

    A side band power re-injection locked (SBPRIL) magnetron is presented in this paper. A tuning stub is placed between the external injection locked (EIL) magnetron and the circulator. Side band power of the EIL magnetron is reflected back to the magnetron. The reflected side band power is reused and pulled back to the central frequency. A phase-locking model is developed from circuit theory to explain the process of reuse of side band power in SBPRIL magnetron. Theoretical analysis proves that the side band power is pulled back to the central frequency of the SBPRIL magnetron, then the amplitude of the RF voltage increases and the phase noise performance is improved. Particle-in-cell (PIC) simulation of a 10-vane continuous wave (CW) magnetron model is presented. Computer simulation predicts that the frequency spectrum’s peak of the SBPRIL magnetron has an increase of 3.25 dB compared with the free running magnetron. The phase noise performance at the side band offset reduces 12.05 dB for the SBPRIL magnetron. Besides, the SBPRIL magnetron experiment is presented. Experimental results show that the spectrum peak rises by 14.29% for SBPRIL magnetron compared with the free running magnetron. The phase noise reduces more than 25 dB at 45-kHz offset compared with the free running magnetron. Project supported by the National Basic Research Program of China (Grant No. 2013CB328902) and the National Natural Science Foundation of China (Grant No. 61501311).

  17. Unbalanced and Minimal Point Equivalent Estimation Second-Order Split-Plot Designs

    NASA Technical Reports Server (NTRS)

    Parker, Peter A.; Kowalski, Scott M.; Vining, G. Geoffrey

    2007-01-01

    Restricting the randomization of hard-to-change factors in industrial experiments is often performed by employing a split-plot design structure. From an economic perspective, these designs minimize the experimental cost by reducing the number of resets of the hard-to- change factors. In this paper, unbalanced designs are considered for cases where the subplots are relatively expensive and the experimental apparatus accommodates an unequal number of runs per whole-plot. We provide construction methods for unbalanced second-order split- plot designs that possess the equivalence estimation optimality property, providing best linear unbiased estimates of the parameters; independent of the variance components. Unbalanced versions of the central composite and Box-Behnken designs are developed. For cases where the subplot cost approaches the whole-plot cost, minimal point designs are proposed and illustrated with a split-plot Notz design.

  18. Magnetron sputtered boron films

    DOEpatents

    Makowiecki, Daniel M.; Jankowski, Alan F.

    1998-01-01

    A method is described for the production of thin boron and titanium/boron films by magnetron sputter deposition. The amorphous boron films contain no morphological growth features, unlike those found when thin films are prepared by various physical vapor deposition processes. Magnetron sputter deposition method requires the use of a high density crystalline boron sputter target which is prepared by hot isostatic pressing. Thin boron films prepared by this method are useful for producing hardened surfaces, surfacing machine tools, etc. and for ultra-thin band pass filters as well as the low Z element in low Z/high Z optical components, such as mirrors which enhance reflectivity from grazing to normal incidence.

  19. Magnetron sputtered boron films

    DOEpatents

    Makowiecki, D.M.; Jankowski, A.F.

    1998-06-16

    A method is described for the production of thin boron and titanium/boron films by magnetron sputter deposition. The amorphous boron films contain no morphological growth features, unlike those found when thin films are prepared by various physical vapor deposition processes. Magnetron sputter deposition method requires the use of a high density crystalline boron sputter target which is prepared by hot isostatic pressing. Thin boron films prepared by this method are useful for producing hardened surfaces, surfacing machine tools, etc. and for ultra-thin band pass filters as well as the low Z element in low Z/high Z optical components, such as mirrors which enhance reflectivity from grazing to normal incidence. 8 figs.

  20. Tutorial: Reactive high power impulse magnetron sputtering (R-HiPIMS)

    NASA Astrophysics Data System (ADS)

    Anders, André

    2017-05-01

    High Power Impulse Magnetron Sputtering (HiPIMS) is a coating technology that combines magnetron sputtering with pulsed power concepts. By applying power in pulses of high amplitude and a relatively low duty cycle, large fractions of sputtered atoms and near-target gases are ionized. In contrast to conventional magnetron sputtering, HiPIMS is characterized by self-sputtering or repeated gas recycling for high and low sputter yield materials, respectively, and both for most intermediate materials. The dense plasma in front of the target has the dual function of sustaining the discharge and providing plasma-assistance to film growth, affecting the microstructure of growing films. Many technologically interesting thin films are compound films, which are composed of one or more metals and a reactive gas, most often oxygen or nitrogen. When reactive gas is added, non-trivial consequences arise for the system because the target may become "poisoned," i.e., a compound layer forms on the target surface affecting the sputtering yield and the yield of secondary electron emission and thereby all other parameters. It is emphasized that the target state depends not only on the reactive gas' partial pressure (balanced via gas flow and pumping) but also on the ion flux to the target, which can be controlled by pulse parameters. This is a critical technological opportunity for reactive HiPIMS (R-HiPIMS). The scope of this tutorial is focused on plasma processes and mechanisms of operation and only briefly touches upon film properties. It introduces R-HiPIMS in a systematic, step-by-step approach by covering sputtering, magnetron sputtering, reactive magnetron sputtering, pulsed reactive magnetron sputtering, HiPIMS, and finally R-HiPIMS. The tutorial is concluded by considering variations of R-HiPIMS known as modulated pulsed power magnetron sputtering and deep-oscillation magnetron sputtering and combinations of R-HiPIMS with superimposed dc magnetron sputtering.

  1. TRANSFORMER FOR JOINING UNBALANCED TO BALANCED TRANSMISSION MEANS

    DOEpatents

    Bittner, B.J.; Opperman, R.H.

    1960-06-28

    An improved transformer is invented for joining an unbalanced transmission means to a balanced transmission means and is useful, for example, in transmitting an electromagnetic signal from a coaxial cable to a balanced dipole antenna.

  2. Simulation of the electric potential and plasma generation coupling in magnetron sputtering discharges

    NASA Astrophysics Data System (ADS)

    Trieschmann, Jan; Krueger, Dennis; Schmidt, Frederik; Brinkmann, Ralf Peter; Mussenbrock, Thomas

    2016-09-01

    Magnetron sputtering typically operated at low pressures below 1 Pa is a widely applied deposition technique. For both, high power impulse magnetron sputtering (HiPIMS) as well as direct current magnetron sputtering (dcMS) the phenomenon of rotating ionization zones (also referred to as spokes) has been observed. A distinct spatial profile of the electric potential has been associated with the latter, giving rise to low, mid, and high energy groups of ions observed at the substrate. The adherent question of which mechanism drives this process is still not fully understood. This query is approached using Monte Carlo simulations of the heavy particle (i.e., ions and neutrals) transport consistently coupled to a pre-specified electron density profile via the intrinsic electric field. The coupling between the plasma generation and the electric potential, which establishes correspondingly, is investigated. While the system is observed to strive towards quasi-neutrality, distinct mechanisms governing the shape of the electric potential profile are identified. This work is supported by the German Research Foundation (DFG) in the frame of the transregional collaborative research centre TRR 87.

  3. Sandblasting induced stress release and enhanced adhesion strength of diamond films deposited on austenite stainless steel

    NASA Astrophysics Data System (ADS)

    Li, Xiao; Ye, Jiansong; Zhang, Hangcheng; Feng, Tao; Chen, Jianqing; Hu, Xiaojun

    2017-08-01

    We firstly used sandblasting to treat austenite stainless steel and then deposited a Cr/CrN interlayer by close field unbalanced magnetron sputtering on it. After that, diamond films were prepared on the interlayer. It is found that the sandblasting process induces phase transition from austenite to martensite in the surface region of the stainless steel, which decreases thermal stress in diamond films due to lower thermal expansion coefficient of martensite phase compared with that of austenite phase. The sandblasting also makes stainless steel's surface rough and the Cr/CrN interlayer film inherits the rough surface. This decreases the carburization extent of the interlayer, increases nucleation density and modifies the stress distribution. Due to lower residual stress and small extent of the interlayer's carburization, the diamond film on sandblast treated austenite stainless steel shows enhanced adhesion strength.

  4. Resonant interaction of the electron beam with a synchronous wave in controlled magnetrons for high-current superconducting accelerators

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kazakevich, G.; Johnson, R.; Lebedev, V.

    A simplified analytical model of the resonant interaction of the beam of Larmor electrons drifting in the crossed constant fields of a magnetron with a synchronous wave providing a phase grouping of the drifting charge was developed to optimize the parameters of an rf resonant injected signal driving the magnetrons for management of phase and power of rf sources with a rate required for superconducting high-current accelerators. The model, which considers the impact of the rf resonant signal injected into the magnetron on the operation of the injection-locked tube, substantiates the recently developed method of fast power control of magnetronsmore » in the range up to 10 dB at the highest generation efficiency, with low noise, precise stability of the carrier frequency, and the possibility of wideband phase control. Experiments with continuous wave 2.45 GHz, 1 kW microwave oven magnetrons have verified the correspondence of the behavior of these tubes to the analytical model. A proof of the principle of the novel method of power control in magnetrons, based on the developed model, was demonstrated in the experiments. The method is attractive for high-current superconducting rf accelerators. This study also discusses vector methods of power control with the rates required for superconducting accelerators, the impact of the rf resonant signal injected into the magnetron on the rate of phase control of the injection-locked tubes, and a conceptual scheme of the magnetron transmitter with highest efficiency for high-current accelerators.« less

  5. Resonant interaction of the electron beam with a synchronous wave in controlled magnetrons for high-current superconducting accelerators

    DOE PAGES

    Kazakevich, G.; Johnson, R.; Lebedev, V.; ...

    2018-06-14

    A simplified analytical model of the resonant interaction of the beam of Larmor electrons drifting in the crossed constant fields of a magnetron with a synchronous wave providing a phase grouping of the drifting charge was developed to optimize the parameters of an rf resonant injected signal driving the magnetrons for management of phase and power of rf sources with a rate required for superconducting high-current accelerators. The model, which considers the impact of the rf resonant signal injected into the magnetron on the operation of the injection-locked tube, substantiates the recently developed method of fast power control of magnetronsmore » in the range up to 10 dB at the highest generation efficiency, with low noise, precise stability of the carrier frequency, and the possibility of wideband phase control. Experiments with continuous wave 2.45 GHz, 1 kW microwave oven magnetrons have verified the correspondence of the behavior of these tubes to the analytical model. A proof of the principle of the novel method of power control in magnetrons, based on the developed model, was demonstrated in the experiments. The method is attractive for high-current superconducting rf accelerators. This study also discusses vector methods of power control with the rates required for superconducting accelerators, the impact of the rf resonant signal injected into the magnetron on the rate of phase control of the injection-locked tubes, and a conceptual scheme of the magnetron transmitter with highest efficiency for high-current accelerators.« less

  6. A Two-stage Injection-locked Magnetron for Accelerators with Superconducting Cavities

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kazakevich, Grigory; Flanagan, Gene; Johnson, Rolland

    2012-05-01

    A concept for a two-stage injection-locked CW magnetron intended to drive Superconducting Cavities (SC) for intensity-frontier accelerators has been proposed. The concept considers two magnetrons in which the output power differs by 15-20 dB and the lower power magnetron being frequency-locked from an external source locks the higher power magnetron. The injection-locked two-stage CW magnetron can be used as an RF power source for Fermilab's Project-X to feed separately each of the 1.3 GHz SC of the 8 GeV pulsed linac. We expect output/locking power ratio of about 30-40 dB assuming operation in a pulsed mode with pulse duration ofmore » ~ 8 ms and repetition rate of 10 Hz. The experimental setup of a two-stage magnetron utilising CW, S-band, 1 kW tubes operating at pulse duration of 1-10 ms, and the obtained results are presented and discussed in this paper.« less

  7. Tutorial: Reactive high power impulse magnetron sputtering (R-HiPIMS)

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Anders, André

    High Power Impulse Magnetron Sputtering (HiPIMS) is a coating technology that combines magnetron sputtering with pulsed power concepts. Furthermore, by applying power in pulses of high amplitude and a relatively low duty cycle, large fractions of sputtered atoms and near-target gases are ionized. In contrast to conventional magnetron sputtering, HiPIMS is characterized by self-sputtering or repeated gas recycling for high and low sputter yield materials, respectively, and both for most intermediate materials. The dense plasma in front of the target has the dual function of sustaining the discharge and providing plasma-assistance to film growth, affecting the microstructure of growing films.more » Many technologically interesting thin films are compound films, which are composed of one or more metals and a reactive gas, most often oxygen or nitrogen. When reactive gas is added, non-trivial consequences arise for the system because the target may become “poisoned,” i.e., a compound layer forms on the target surface affecting the sputtering yield and the yield of secondary electron emission and thereby all other parameters. It is emphasized that the target state depends not only on the reactive gas' partial pressure (balanced via gas flow and pumping) but also on the ion flux to the target, which can be controlled by pulse parameters. This is a critical technological opportunity for reactive HiPIMS (R-HiPIMS). The scope of this tutorial is focused on plasma processes and mechanisms of operation and only briefly touches upon film properties. It introduces R-HiPIMS in a systematic, step-by-step approach by covering sputtering, magnetron sputtering, reactive magnetron sputtering, pulsed reactive magnetron sputtering, HiPIMS, and finally R-HiPIMS. The tutorial is concluded by considering variations of R-HiPIMS known as modulated pulsed power magnetron sputtering and deep-oscillation magnetron sputtering and combinations of R-HiPIMS with superimposed dc magnetron

  8. Tutorial: Reactive high power impulse magnetron sputtering (R-HiPIMS)

    DOE PAGES

    Anders, André

    2017-03-21

    High Power Impulse Magnetron Sputtering (HiPIMS) is a coating technology that combines magnetron sputtering with pulsed power concepts. Furthermore, by applying power in pulses of high amplitude and a relatively low duty cycle, large fractions of sputtered atoms and near-target gases are ionized. In contrast to conventional magnetron sputtering, HiPIMS is characterized by self-sputtering or repeated gas recycling for high and low sputter yield materials, respectively, and both for most intermediate materials. The dense plasma in front of the target has the dual function of sustaining the discharge and providing plasma-assistance to film growth, affecting the microstructure of growing films.more » Many technologically interesting thin films are compound films, which are composed of one or more metals and a reactive gas, most often oxygen or nitrogen. When reactive gas is added, non-trivial consequences arise for the system because the target may become “poisoned,” i.e., a compound layer forms on the target surface affecting the sputtering yield and the yield of secondary electron emission and thereby all other parameters. It is emphasized that the target state depends not only on the reactive gas' partial pressure (balanced via gas flow and pumping) but also on the ion flux to the target, which can be controlled by pulse parameters. This is a critical technological opportunity for reactive HiPIMS (R-HiPIMS). The scope of this tutorial is focused on plasma processes and mechanisms of operation and only briefly touches upon film properties. It introduces R-HiPIMS in a systematic, step-by-step approach by covering sputtering, magnetron sputtering, reactive magnetron sputtering, pulsed reactive magnetron sputtering, HiPIMS, and finally R-HiPIMS. The tutorial is concluded by considering variations of R-HiPIMS known as modulated pulsed power magnetron sputtering and deep-oscillation magnetron sputtering and combinations of R-HiPIMS with superimposed dc magnetron

  9. The role of the altruistic unbalanced chain in exchange living donor renal transplantation: single-center experience.

    PubMed

    Ahn, B K; Kwon, O J; Kang, C M

    2012-01-01

    The exchange donor program in renal transplantation is an efficient solution for recipients with a blood type or crossmatch-incompatible donor. However, this program has some difficulties to define unacceptable human leukocyte antigen matches, deteriorating clinical potential recipient condition, and withdrawal of donor consent. We analyzed the outcomes of exchange donor renal transplantation through the altruistic unbalanced chain. Among 152 cases of exchange donor renal transplantation from 1991 to 2010 in our hospital, we performed 58 procedures through altruistic unbalanced chains. We compared their outcomes with the direct and balanced chain group. We analyzed retrospectively whether this program expanded the donor pool, seeking better immunologic, size, and age matching. The graft survival and acute rejection rates did not differ significantly in the two groups. Of 152 cases, 58 (38.2%) renal transplantations were performed through an unbalanced chain. Seventeen waiting list recipients were transplanted through an altruistic unbalanced chain. In blood type O recipients (n = 32), the causes of registration in the exchange program were ABO incompatibility (93.3%), and positive crossmatch (6.7%). Nine altruistic blood type O donors and 9 (28.1%) type O recipients underwent transplantations through this chain. We suggest the altruistic unbalanced chain may expand the donor pool with advantages for difficult-to-match pairs. The disadvantages of type O recipients may be overcome through the use of an unbalanced chain. The altruistic unbalanced exchange transplantation program can help easy-to-match subjects, shortening the waiting periods. Copyright © 2012 Elsevier Inc. All rights reserved.

  10. African crop yield reductions due to increasingly unbalanced Nitrogen and Phosphorus consumption

    NASA Astrophysics Data System (ADS)

    van der Velde, Marijn; Folberth, Christian; Balkovič, Juraj; Ciais, Philippe; Fritz, Steffen; Janssens, Ivan A.; Obersteiner, Michael; See, Linda; Skalský, Rastislav; Xiong, Wei; Peñuealas, Josep

    2014-05-01

    The impact of soil nutrient depletion on crop production has been known for decades, but robust assessments of the impact of increasingly unbalanced nitrogen (N) and phosphorus (P) application rates on crop production are lacking. Here, we use crop response functions based on 741 FAO maize crop trials and EPIC crop modeling across Africa to examine maize yield deficits resulting from unbalanced N:P applications under low, medium, and high input scenarios, for past (1975), current, and future N:P mass ratios of respectively, 1:0.29, 1:0.15, and 1:0.05. At low N inputs (10 kg/ha), current yield deficits amount to 10% but will increase up to 27% under the assumed future N:P ratio, while at medium N inputs (50 kg N/ha), future yield losses could amount to over 40%. The EPIC crop model was then used to simulate maize yields across Africa. The model results showed relative median future yield reductions at low N inputs of 40%, and 50% at medium and high inputs, albeit with large spatial variability. Dominant low-quality soils such as Ferralsols, which are strongly adsorbing P, and Arenosols with a low nutrient retention capacity, are associated with a strong yield decline, although Arenosols show very variable crop yield losses at low inputs. Optimal N:P ratios, i.e. those where the lowest amount of applied P produces the highest yield (given N input) where calculated with EPIC to be as low as 1:0.5. Finally, we estimated the additional P required given current N inputs, and given N inputs that would allow Africa to close yield gaps (ca. 70%). At current N inputs, P consumption would have to increase 2.3-fold to be optimal, and to increase 11.7-fold to close yield gaps. The P demand to overcome these yield deficits would provide a significant additional pressure on current global extraction of P resources.

  11. Phase Grouping of Larmor Electrons by a Synchronous Wave in Controlled Magnetrons

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kazakevich, G.; Johnson, R.; Lebedev, V.

    A simplified analytical model based on the charge drift approximation has been developed. It considers the resonant interaction of the synchronous wave with the flow of Larmor electrons in a magnetron. The model predicts stable coherent generation of the tube above and below the threshold of self-excitation. This occurs if the magnetron is driven by a sufficient resonant injected signal (up to -10 dB). The model substantiates precise stability, high efficiency and low noise at the range of the magnetron power control over 10 dB by variation of the magnetron current. The model and the verifying experiments with 2.45 GHz,more » 1 kW magnetrons are discussed.« less

  12. Highly conductive ultrathin Co films by high-power impulse magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Jablonka, L.; Riekehr, L.; Zhang, Z.; Zhang, S.-L.; Kubart, T.

    2018-01-01

    Ultrathin Co films deposited on SiO2 with conductivities exceeding that of Cu are demonstrated. Ionized deposition implemented by high-power impulse magnetron sputtering (HiPIMS) is shown to result in smooth films with large grains and low resistivities, namely, 14 µΩ cm at a thickness of 40 nm, which is close to the bulk value of Co. Even at a thickness of only 6 nm, a resistivity of 35 µΩ cm is obtained. The improved film quality is attributed to a higher nucleation density in the Co-ion dominated plasma in HiPIMS. In particular, the pulsed nature of the Co flux as well as shallow ion implantation of Co into SiO2 can increase the nucleation density. Adatom diffusion is further enhanced in the ionized process, resulting in a dense microstructure. These results are in contrast to Co deposited by conventional direct current magnetron sputtering where the conductivity is reduced due to smaller grains, voids, rougher interfaces, and Ar incorporation. The resistivity of the HiPIMS films is shown to be in accordance with models by Mayadas-Shatzkes and Sondheimer which consider grain-boundary and surface-scattering.

  13. Research and Development for an Alternative RF Source Using Magnetrons in CEBAF

    NASA Astrophysics Data System (ADS)

    Jacobs, Andrew

    2016-09-01

    At Jefferson Lab, klystrons are currently used as a radiofrequency (RF) power source for the 1497 MHz Continuous Electron Beam Accelerator Facility (CEBAF) Continuous Wave (CW) system. A drop-in replacement for the klystrons in the form of a system of magnetrons is being developed. The klystron DC-RF efficiency at CEBAF is 35-51% while the estimated magnetron efficiency is 80-90%. Thus, the introduction of magnetrons to CEBAF will have enormous benefits in terms of electrical power saving. The primary focus of this project was to characterize a magnetron's frequency pushing and pulling curves at 2.45 GHz with stub tuner and anode current adjustments so that a Low Level RF controller for a new 1.497 GHz magnetron can be built. A Virtual Instrument was created in LabVIEW, and data was taken. The resulting data allowed for the creation of many constant lines of frequency and output power. Additionally, the results provided a characterization of magnetron oven temperature drift over the operation time and the relationship between anode current and frequency. Using these results, the control model of different variables and their feedback or feedforward that affect the frequency pushing and pulling of the magnetron is better developed. Department of Energy, Science Undergraduate Laboratory Internships, and Jefferson Lab.

  14. Mo doped DLC nanocomposite coatings with improved mechanical and blood compatibility properties

    NASA Astrophysics Data System (ADS)

    Tang, X. S.; Wang, H. J.; Feng, L.; Shao, L. X.; Zou, C. W.

    2014-08-01

    Mo (molybdenum) doped diamond like carbon (Mo-DLC) coatings with improved mechanical and blood compatibility properties were deposited by closed field unbalanced magnetron sputtering. The undoped and Mo-doped DLC coatings were analyzed by various characterization techniques such as Raman spectra, Atomic force microscopy, and temperature-dependent frictional wear testing. The results showed that the Mo-DLC coating with low Mo concentration was a effective protective coating with reduced residual stress and increased cohesive strength, and kept good wear resistance at the ambient temperature of 500 °C. The blood compatibility of Mo-DLC coatings was investigated by platelet adhesion. The results showed that the amount of thrombus on the Mo-DLC nanocomposite coatings was much less than that of thrombus on pyrolytic carbon films. The Mo-DLC nanocomposite coatings would be a new kind of promising materials applied to artificial heart valve and endovascula stent.

  15. Metal copper films deposited on cenosphere particles by magnetron sputtering method

    NASA Astrophysics Data System (ADS)

    Yu, Xiaozheng; Xu, Zheng; Shen, Zhigang

    2007-05-01

    Metal copper films with thicknesses from several nanometres to several micrometres were deposited on the surface of cenosphere particles by the magnetron sputtering method under different working conditions. An ultrasonic vibrating generator equipped with a conventional magnetron sputtering apparatus was used to prevent the cenosphere substrates from accumulating during film growth. The surface morphology, the chemical composition, the average grain size and the crystallization of cenosphere particles were characterized by field emission scanning electron microscopy (FE-SEM), inductively coupled plasma-atom emission spectrometer, x-ray photoelectron spectroscopy and x-ray diffraction (XRD) analysis, respectively, before and after the plating process. The results indicate that the copper films were successfully deposited on cenosphere particles. It was found from the FE-SEM results that the films were well compacted and highly uniform in thickness. The XRD results show that the copper film coated on cenospheres has a face centred cubic structure and the crystallization of the film sample increases with increasing sputtering power.

  16. Steady-State Modeling of Modular Multilevel Converter Under Unbalanced Grid Conditions

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Shi, Xiaojie M.; Wang, Zhiqiang; Liu, Bo

    This paper presents a steady-state model of MMC for the second-order phase voltage ripple prediction under unbalanced conditions, taking the impact of negative-sequence current control into account. From the steady-state model, a circular relationship is found among current and voltage quantities, which can be used to evaluate the magnitudes and initial phase angles of different circulating current components. Moreover, in order to calculate the circulating current in a point-to-point MMC-based HVdc system under unbalanced grid conditions, the derivation of equivalent dc impedance of an MMC is discussed as well. According to the dc impedance model, an MMC inverter can bemore » represented as a series connected R-L-C branch, with its equivalent resistance and capacitance directly related to the circulating current control parameters. Experimental results from a scaled-down three-phase MMC system under an emulated single-line-to-ground fault are provided to support the theoretical analysis and derived model. In conclusion, this new models provides an insight into the impact of different control schemes on the fault characteristics and improves the understanding of the operation of MMC under unbalanced conditions.« less

  17. Steady-State Modeling of Modular Multilevel Converter Under Unbalanced Grid Conditions

    DOE PAGES

    Shi, Xiaojie M.; Wang, Zhiqiang; Liu, Bo; ...

    2016-11-16

    This paper presents a steady-state model of MMC for the second-order phase voltage ripple prediction under unbalanced conditions, taking the impact of negative-sequence current control into account. From the steady-state model, a circular relationship is found among current and voltage quantities, which can be used to evaluate the magnitudes and initial phase angles of different circulating current components. Moreover, in order to calculate the circulating current in a point-to-point MMC-based HVdc system under unbalanced grid conditions, the derivation of equivalent dc impedance of an MMC is discussed as well. According to the dc impedance model, an MMC inverter can bemore » represented as a series connected R-L-C branch, with its equivalent resistance and capacitance directly related to the circulating current control parameters. Experimental results from a scaled-down three-phase MMC system under an emulated single-line-to-ground fault are provided to support the theoretical analysis and derived model. In conclusion, this new models provides an insight into the impact of different control schemes on the fault characteristics and improves the understanding of the operation of MMC under unbalanced conditions.« less

  18. Magnetron with flux switching cathode and method of operation

    DOEpatents

    Aaron, David B.; Wiley, John D.

    1989-01-01

    A magnetron sputtering apparatus is formed with a plurality of cells each for generating an independent magnetic field within a different region in the chamber of the apparatus. Each magnetic field aids in maintaining an ion plasma in the respective region of the chamber. One of a plurality of sputtering material targets is positioned on an electrode adjacent to each region so that said ions strike the target ejecting some of the target material. By selectively generating each magnetic field, the ion plasma may be moved from region to region to sputter material from different targets. The sputtered material becomes deposited on a substrate mounted on another electrode within the chamber. The duty cycle of each cell can be dynamically varied during the deposition to produce a layer having a graded composition throughout its thickness.

  19. Plasma reactivity in high-power impulse magnetron sputtering through oxygen kinetics

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Vitelaru, Catalin; National Institute for Optoelectronics, Magurele-Bucharest, RO 077125; Lundin, Daniel

    2013-09-02

    The atomic oxygen metastable dynamics in a Reactive High-Power Impulse Magnetron Sputtering (R-HiPIMS) discharge has been characterized using time-resolved diode laser absorption in an Ar/O{sub 2} gas mixture with a Ti target. Two plasma regions are identified: the ionization region (IR) close to the target and further out the diffusion region (DR), separated by a transition region. The μs temporal resolution allows identifying the main atomic oxygen production and destruction routes, which are found to be very different during the pulse as compared to the afterglow as deduced from their evolution in space and time.

  20. Characterization of Magnetron Sputtered Copper-Nickel Thin Film and Alloys

    DTIC Science & Technology

    2016-09-01

    ARL-TR-7783 ● SEP 2016 US Army Research Laboratory Characterization of Magnetron Sputtered Copper-Nickel Thin Films and Alloys...TR-7783 ● SEP 2016 US Army Research Laboratory Characterization of Magnetron Sputtered Copper-Nickel Thin Films and Alloys by Eugene...

  1. Structure and tribological behavior of Pb-Ti/MoS2 nanoscaled multilayer films deposited by magnetron sputtering method

    NASA Astrophysics Data System (ADS)

    Li, Hao; Xie, Mingling; Zhang, Guangan; Fan, Xiaoqiang; Li, Xia; Zhu, Minhao; Wang, Liping

    2018-03-01

    The Pb-Ti/MoS2 nanoscaled multilayer films with different bilayer period were deposited by unbalanced magnetron sputtering system. The morphology, microstructure, mechanical and tribological properties of the films were investigated. It was found that the film changed from multilayer structure to composite structure as the bilayer period decreased from 25 nm to 6 nm, due to the diffusion effect. The multilayer film showed a pronounced (002) diffraction peak, the growth of the MoS2 platelets below the interface were affected by Pb and Ti, and the c-axis of MoS2 platelets were inclined to the substrate at an angle of -30° to 30°. The hardness of the film ranged from 5.9 to 7.2 GPa depending on the bilayer period. The tribological behavior of the films was performed under vacuum, and the friction coefficient were typically below 0.25. Furthermore, the nanoscale multilayer film with a bilayer period of 20 nm exhibits much better mechanical and tribological properties than pure MoS2. The result indicates that the nanoscale multilayer is a design methodology for developing high basal plane oriented and vacuum solid lubricating MoS2 based materials.

  2. Very low pressure high power impulse triggered magnetron sputtering

    DOEpatents

    Anders, Andre; Andersson, Joakim

    2013-10-29

    A method and apparatus are described for very low pressure high powered magnetron sputtering of a coating onto a substrate. By the method of this invention, both substrate and coating target material are placed into an evacuable chamber, and the chamber pumped to vacuum. Thereafter a series of high impulse voltage pulses are applied to the target. Nearly simultaneously with each pulse, in one embodiment, a small cathodic arc source of the same material as the target is pulsed, triggering a plasma plume proximate to the surface of the target to thereby initiate the magnetron sputtering process. In another embodiment the plasma plume is generated using a pulsed laser aimed to strike an ablation target material positioned near the magnetron target surface.

  3. Magnetron with flux switching cathode and method of operation

    DOEpatents

    Aaron, D.B.; Wiley, J.D.

    1989-09-12

    A magnetron sputtering apparatus is formed with a plurality of cells each for generating an independent magnetic field within a different region in the chamber of the apparatus. Each magnetic field aids in maintaining an ion plasma in the respective region of the chamber. One of a plurality of sputtering material targets is positioned on an electrode adjacent to each region so that said ions strike the target ejecting some of the target material. By selectively generating each magnetic field, the ion plasma may be moved from region to region to sputter material from different targets. The sputtered material becomes deposited on a substrate mounted on another electrode within the chamber. The duty cycle of each cell can be dynamically varied during the deposition to produce a layer having a graded composition throughout its thickness. 5 figs.

  4. Sequential Service Restoration for Unbalanced Distribution Systems and Microgrids

    DOE PAGES

    Chen, Bo; Chen, Chen; Wang, Jianhui; ...

    2017-07-07

    The resilience and reliability of modern power systems are threatened by increasingly severe weather events and cyber-physical security events. An effective restoration methodology is desired to optimally integrate emerging smart grid technologies and pave the way for developing self-healing smart grids. In this paper, a sequential service restoration (SSR) framework is proposed to generate restoration solutions for distribution systems and microgrids in the event of large-scale power outages. The restoration solution contains a sequence of control actions that properly coordinate switches, distributed generators, and switchable loads to form multiple isolated microgrids. The SSR can be applied for three-phase unbalanced distributionmore » systems and microgrids and can adapt to various operation conditions. Mathematical models are introduced for three-phase unbalanced power flow, voltage regulators, transformers, and loads. Furthermore, the SSR problem is formulated as a mixed-integer linear programming model, and its effectiveness is evaluated via the modified IEEE 123 node test feeder.« less

  5. Sequential Service Restoration for Unbalanced Distribution Systems and Microgrids

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chen, Bo; Chen, Chen; Wang, Jianhui

    The resilience and reliability of modern power systems are threatened by increasingly severe weather events and cyber-physical security events. An effective restoration methodology is desired to optimally integrate emerging smart grid technologies and pave the way for developing self-healing smart grids. In this paper, a sequential service restoration (SSR) framework is proposed to generate restoration solutions for distribution systems and microgrids in the event of large-scale power outages. The restoration solution contains a sequence of control actions that properly coordinate switches, distributed generators, and switchable loads to form multiple isolated microgrids. The SSR can be applied for three-phase unbalanced distributionmore » systems and microgrids and can adapt to various operation conditions. Mathematical models are introduced for three-phase unbalanced power flow, voltage regulators, transformers, and loads. Furthermore, the SSR problem is formulated as a mixed-integer linear programming model, and its effectiveness is evaluated via the modified IEEE 123 node test feeder.« less

  6. Gravitational Scattering Amplitudes and Closed String Field Theory in the Proper-Time Gauge

    NASA Astrophysics Data System (ADS)

    Lee, Taejin

    2018-01-01

    We construct a covariant closed string field theory by extending recent works on the covariant open string field theory in the proper-time gauge. Rewriting the string scattering amplitudes generated by the closed string field theory in terms of the Polyakov string path integrals, we identify the Fock space representations of the closed string vertices. We show that the Fock space representations of the closed string field theory may be completely factorized into those of the open string field theory. It implies that the well known Kawai-Lewellen-Tye (KLT) relations of the first quantized string theory may be promoted to the second quantized closed string theory. We explicitly calculate the scattering amplitudes of three gravitons by using the closed string field theory in the proper-time gauge.

  7. Processing of Signals from Fiber Bragg Gratings Using Unbalanced Interferometers

    NASA Technical Reports Server (NTRS)

    Adamovsky, Grigory; Juergens, Jeff; Floyd, Bertram

    2005-01-01

    Fiber Bragg gratings (FBG) have become preferred sensory structures in fiber optic sensing system. High sensitivity, embedability, and multiplexing capabilities make FBGs superior to other sensor configurations. The main feature of FBGs is that they respond in the wavelength domain with the wavelength of the returned signal as the indicator of the measured parameter. The wavelength is then converted to optical intensity by a photodetector to detect corresponding changes in intensity. This wavelength-to-intensity conversion is a crucial part in any FBG-based sensing system. Among the various types of wavelength-to-intensity converters, unbalanced interferometers are especially attractive because of their small weight and volume, lack of moving parts, easy integration, and good stability. In this paper we investigate the applicability of unbalanced interferometers to analyze signals reflected from Bragg gratings. Analytical and experimental data are presented.

  8. Construction, Test and Delivery of Standardized Coaxial Magnetron.

    DTIC Science & Technology

    1981-09-23

    Cavity Pressurization and Pressure Switch . .. 13 4.0 PERFORNANCE OF BAND IV, VMS-1104 COAXIAL AAGNETRON. 14 4.1 Initial Test of Band IV, VNS-1I04, S/N...of the magnetron. 3.7 Ship Air Pressure Switch The insertion of the magnetron deeper into the cabinet to obtain proper alignment of the tube and...waveguide run required reloca- tion of the ship air pressure switch . The switch was moved approxi- mately two inches deeper into the cabinet and rebolted

  9. Reactive magnetron sputtering deposition of bismuth tungstate onto titania nanoparticles for enhancing visible light photocatalytic activity

    NASA Astrophysics Data System (ADS)

    Ratova, Marina; Kelly, Peter J.; West, Glen T.; Tosheva, Lubomira; Edge, Michele

    2017-01-01

    Titanium dioxide - bismuth tungstate composite materials were prepared by pulsed DC reactive magnetron sputtering of bismuth and tungsten metallic targets in argon/oxygen atmosphere onto anatase and rutile titania nanoparticles. The use of an oscillating bowl placed beneath the two magnetrons arranged in a co-planar closed field configuration enabled the deposition of bismuth tungstate onto loose powders, rather than a solid substrate. The atomic ratio of the bismuth/tungsten coatings was controlled by varying the power applied to each target. The effect of the bismuth tungstate coatings on the phase, optical and photocatalytic properties of titania was investigated by X-ray diffraction, energy-dispersive X-ray spectroscopy (EDX), Brunauer-Emmett-Teller (BET) surface area measurements, transmission electron microscopy (TEM), UV-vis diffuse reflectance spectroscopy and an acetone degradation test. The latter involved measurements of the rate of CO2 evolution under visible light irradiation of the photocatalysts, which indicated that the deposition of bismuth tungstate resulted in a significant enhancement of visible light activity, for both anatase and rutile titania particles. The best results were achieved for coatings with a bismuth to tungsten atomic ratio of 2:1. In addition, the mechanism by which the photocatalytic activity of the TiO2 nanoparticles was enhanced by compounding it with bismuth tungstate was studied by microwave cavity perturbation. The results of these tests confirmed that such enhancement of the photocatalytic properties is due to more efficient photogenerated charge carrier separation, as well as to the contribution of the intrinsic photocatalytic properties of Bi2WO6.

  10. A novel passive micromixer based on unbalanced splits and collisions of fluid streams

    NASA Astrophysics Data System (ADS)

    Ansari, Mubashshir Ahmad; Kim, Kwang-Yong; Anwar, Khalid; Kim, Sun Min

    2010-05-01

    A new passive micromixer based on the concept of unbalanced splits and cross-collisions of fluid streams is designed and fabricated. Experimental and numerical studies have been carried out on the micromixer at Reynolds numbers ranging from 10 to 80. The three-dimensional Navier-Stokes equations have been used to analyze the mixing and flow behavior of the micromixer, which is composed of two sub-channels of unequal widths which repeatedly undergo splitting and recombination. The difference between the mass flow rates in the two sub-channels creates an unbalanced collision of the two fluid streams. Mixing is mainly due to the combined effect of unbalanced collisions of the fluid streams and Dean vortices. The micromixer shows interesting mixing behavior for different ratios of the widths of the two split sub-channels. The sub-channels wherein the major sub-channel is twice as wide as the minor sub-channel exhibit the highest mixing performance at Reynolds numbers larger than 40. The results show the lowest mixing performance for the case of uniform width, where balanced collisions occur.

  11. Data Normalization of (1)H NMR Metabolite Fingerprinting Data Sets in the Presence of Unbalanced Metabolite Regulation.

    PubMed

    Hochrein, Jochen; Zacharias, Helena U; Taruttis, Franziska; Samol, Claudia; Engelmann, Julia C; Spang, Rainer; Oefner, Peter J; Gronwald, Wolfram

    2015-08-07

    Data normalization is an essential step in NMR-based metabolomics. Conducted properly, it improves data quality and removes unwanted biases. The choice of the appropriate normalization method is critical and depends on the inherent properties of the data set in question. In particular, the presence of unbalanced metabolic regulation, where the different specimens and cohorts under investigation do not contain approximately equal shares of up- and down-regulated features, may strongly influence data normalization. Here, we demonstrate the suitability of the Shapiro-Wilk test to detect such unbalanced regulation. Next, employing a Latin-square design consisting of eight metabolites spiked into a urine specimen at eight different known concentrations, we show that commonly used normalization and scaling methods fail to retrieve true metabolite concentrations in the presence of increasing amounts of glucose added to simulate unbalanced regulation. However, by learning the normalization parameters on a subset of nonregulated features only, Linear Baseline Normalization, Probabilistic Quotient Normalization, and Variance Stabilization Normalization were found to account well for different dilutions of the samples without distorting the true spike-in levels even in the presence of marked unbalanced metabolic regulation. Finally, the methods described were applied successfully to a real world example of unbalanced regulation, namely, a set of plasma specimens collected from patients with and without acute kidney injury after cardiac surgery with cardiopulmonary bypass use.

  12. Altruistic unbalanced paired kidney exchange at Columbia University/New York-Presbyterian hospital: rationale and practical considerations.

    PubMed

    Ratner, Lloyd E; Ratner, Emily R; Kelly, Joan; Carrol, Maureen; Cherwinski, Karyn; Ernst, Victoria; Rana, Abbas

    2008-01-01

    Paired kidney exchanges are being used with increasing frequency to overcome humoral immunologic incompatibilities between patients in need of renal transplantation and their potential live donors. Altruistic unbalanced exchanges utilize compatible donor/recipient pairs in order to facilitate the transplantation of a patient with an incompatible donor. We have now performed several altruistic unbalanced paired kidney exchanges at our institution. Also, we have surveyed potential donors and recipients regarding their attitudes toward participating in altruistic unbalanced paired kidney exchanges. Patients are most amenable to participation if they perceive a benefit from trading away a compatible donor. Given the number of compatible live donor transplants performed annually, if practiced on a broad scale, altruistic unbalancedpaired kidney exchanges can have a profound impact upon the supply of kidneys for transplantation. These exchanges can be performed at individual centers without the requirement for largesharing pools or complex computer algorithms. However, there are a number of ethical and logistical considerations that must be addressed. Altruistic unbalanced paired kidney exchanges represent a major paradigm shift in renal transplantation, in that a private resource (i.e. the live kidney donor) is converted to a shared or public one.

  13. Visualization in Mechanics: The Dynamics of an Unbalanced Roller

    ERIC Educational Resources Information Center

    Cumber, Peter S.

    2017-01-01

    It is well known that mechanical engineering students often find mechanics a difficult area to grasp. This article describes a system of equations describing the motion of a balanced and an unbalanced roller constrained by a pivot arm. A wide range of dynamics can be simulated with the model. The equations of motion are embedded in a graphical…

  14. A control strategy for grid-side converter of DFIG under unbalanced condition based on Dig SILENT/Power Factory

    NASA Astrophysics Data System (ADS)

    Han, Pingping; Zhang, Haitian; Chen, Lingqi; Zhang, Xiaoan

    2018-01-01

    The models of doubly fed induction generator (DFIG) and its grid-side converter (GSC) are established under unbalanced grid condition based on DIgSILENT/PowerFactory. According to the mathematical model, the vector equations of positive and negative sequence voltage and current are deduced in the positive sequence synchronous rotating reference frame d-q-0 when the characteristics of the simulation software are considered adequately. Moreover, the reference value of current component of GSC in the positive sequence frame d-q-0 under unbalanced condition can be obtained to improve the traditional control of GSC when the national issue of unbalanced current limits is combined. The simulated results indicate that the control strategy can restrain negative sequence current and the two times frequency power wave of GSC’s ac side effectively. The voltage of DC bus can be maintained a constant to ensure the uninterrupted operation of DFIG under unbalanced grid condition eventually.

  15. What drives health care expenditure?--Baumol's model of 'unbalanced growth' revisited.

    PubMed

    Hartwig, Jochen

    2008-05-01

    The share of health care expenditure in GDP rises rapidly in virtually all OECD countries, causing increasing concern among politicians and the general public. Yet, economists have to date failed to reach an agreement on what the main determinants of this development are. This paper revisits Baumol's [Baumol, W.J., 1967. Macroeconomics of unbalanced growth: the anatomy of urban crisis. American Economic Review 57 (3), 415-426] model of 'unbalanced growth', showing that the latter offers a ready explanation for the observed inexorable rise in health care expenditure. The main implication of Baumol's model in this context is that health care expenditure is driven by wage increases in excess of productivity growth. This hypothesis is tested empirically using data from a panel of 19 OECD countries. Our tests yield robust evidence in favor of Baumol's theory.

  16. Effect of control surface mass unbalance on the stability of a closed-loop active control system

    NASA Technical Reports Server (NTRS)

    Nissim, E.

    1989-01-01

    The effects on stability of inertial forces arising from closed-loop activation of mass-unbalanced control surfaces are studied analytically using inertial energy approach, similar to the aerodynamic energy approach used for flutter suppression. The limitations of a single control surface like a leading-edge (LE) control or a trailing-edge (TE) control are demonstrated and compared to the superior combined LE-TE mass unbalanced system. It is shown that a spanwise section for sensor location can be determined which ensures minimum sensitivity to the mode shapes of the aircraft. It is shown that an LE control exhibits compatibility between inertial stabilization and aerodynamic stabilization, and that a TE control lacks such compatibility. The results of the present work should prove valuable, both for the purpose of flutter suppression using mass unbalanced control surfaces, or for the stabilization of structural modes of large space structures by means of inertial forces.

  17. Phased Array Technology with Phase and Amplitude Controlled Magnetron for Microwave Power Transmission

    NASA Astrophysics Data System (ADS)

    Shinohara, N.; Matsumoto, H.

    2004-12-01

    We need a microwave power transmitter with light weight and high DC-RF conversion efficiency for an economical SSPS (Space Solar Power System). We need a several g/W for a microwave power transmission (MPT) system with a phased array with 0.0001 degree of beam control accuracy (=tan-1 (100m/36,000km)) and over 80 % of DC-RF conversion efficiency when the weight of the 1GW-class SPS is below a several thousand ton - a several tens of thousand ton. We focus a microwave tube, especially magnetron by economical reason and by the amount of mass-production because it is commonly used for microwave oven in the world. At first, we have developed a phase controlled magnetron (PCM) with different technologies from what Dr. Brown developed. Next we have developed a phase and amplitude controlled magnetron (PACM). For the PACM, we add a feedback to magnetic field of the PCM with an external coil to control and stabilize amplitude of the microwave. We succeed to develop the PACM with below 10-6 of frequency stability and within 1 degree of an error in phase and within 1% of amplitude. We can control a phase and amplitude of the PACM and we have developed a phased array the PCMs. With the PCM technology, we have developed a small light weight MPT transmitter COMET (Compact Microwave Energy Transmitter) with consideration of heat radiation for space use and with consideration of mobility to space.

  18. On the Effects of a Spacecraft Subcarrier Unbalanced Modulator

    NASA Technical Reports Server (NTRS)

    Nguyen, Tien Manh

    1993-01-01

    This paper presents mathematical models with associated analysis of the deleterious effects which a spacecraft's subcarrier unbalanced modulator has on the performance of a phase-modulated residual carrier communications link. The undesired spectral components produced by the phase and amplitude imbalances in the subcarrier modulator can cause (1) potential interference to the carrier tracking and (2) degradation in the telemetry bit signal-to-noise ratio (SNR). A suitable model for the unbalanced modulator is developed and the threshold levels of undesired components that fall into the carrier tracking loop are determined. The distribution of the carrier phase error caused by the additive White Gaussian noise (AWGN) and undesired component at the residual RF carrier is derived for the limiting cases. Further, this paper analyses the telemetry bit signal-to-noise ratio degradations due to undesirable spectral components as well as the carrier tracking phase error induced by phase and amplitude imbalances. Numerical results which indicate the sensitivity of the carrier tracking loop and the telemetry symbol-error rate (SER) to various parameters of the models are also provided as a tool in the design of the subcarrier balanced modulator.

  19. Analysis of temperature changes on three-phase synchronous generator using infrared: comparison between balanced and unbalanced load

    NASA Astrophysics Data System (ADS)

    Amien, S.; Yoga, W.; Fahmi, F.

    2018-02-01

    Synchronous generators are a major tool in an electrical energy generating systems, the load supplied by the generator is unbalanced. This paper discusses the effect of synchronous generator temperature on the condition of balanced load and unbalanced load, which will then be compared with the measurement result of both states of the generator. Unbalanced loads can be caused by various asymmetric disturbances in the power system and the failure of load forecasting studies so that the load distribution in each phase is not the same and causing the excessive heat of the generator. The method used in data collection was by using an infrared thermometer and resistance calculation method. The temperature comparison result between the resistive, inductive and capacitive loads in the highest temperature balance occured when the generator is loaded with a resistive load, where T = 31.9 ° C and t = 65 minutes. While in a state of unbalanced load the highest temperature occured when the generator is loaded with a capacitive load, where T = 40.1 ° C and t = 60 minutes. By understanding this behavior, we can maintain the generator for longer operation life.

  20. Effect of hafnium doping on density of states in dual-target magnetron co-sputtering HfZnSnO thin film transistors

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Huang, Chuan-Xin; Li, Jun, E-mail: SHUniverjunli@163.com; Fu, Yi-Zhou

    2015-11-23

    This study investigates the effect of hafnium doping on the density of states (DOSs) in HfZnSnO thin film transistors fabricated by dual-target magnetron co-sputtering system. The DOSs is extracted by temperature-dependent field-effect measurements, and they decrease from 1.1 × 10{sup 17} to 4.6 × 10{sup 16 }eV/cm{sup 3} with increasing the hafnium concentrations. The behavior of DOSs for the increasing hafnium concentration HfZnSnO thin film transistors can be confirmed by both the reduction of ΔV{sub T} under bias stress and the trapping charges calculated by capacitance voltage measurements. It suggests that the reduction in DOSs due to the hafnium doping is closely related with themore » bias stability and thermal stability.« less

  1. Transient analysis of unbalanced short circuits of the ERDA-NASA 100 kW wind turbine alternator

    NASA Technical Reports Server (NTRS)

    Hwang, H. H.; Gilbert, L. J.

    1976-01-01

    Unbalanced short-circuit faults on the alternator of the ERDA-NASA Mod-O100-kW experimental wind turbine are studied. For each case, complete solutions for armature, field, and damper-circuit currents; short-circuit torque; and open-phase voltage are derived directly by a mathematical analysis. Formulated results are tabulated. For the Mod-O wind turbine alternator, numerical calculations are given, and results are presented by graphs. Comparisons for significant points among the more important cases are summarized. For these cases the transients are found to be potentially severe. The effect of the alternator neutral-to-ground impedance is evaluated.

  2. Magnetron injection gun for a broadband gyrotron backward-wave oscillator

    NASA Astrophysics Data System (ADS)

    Yuan, C. P.; Chang, T. H.; Chen, N. C.; Yeh, Y. S.

    2009-07-01

    The magnetron injection gun is capable of generating relativistic electron beam with high velocity ratio and low velocity spread for a gyrotron backward-wave oscillator (gyro-BWO). However, the velocity ratio (α) varies drastically against both the magnetic field and the beam voltage, which significantly limits the tuning bandwidth of a gyro-BWO. This study remedies this drawback by adding a variable trim field to adjust the magnetic compression ratio when changing the operating conditions. Theoretical results obtained by employing a two-dimensional electron gun code (EGUN) demonstrate a constant velocity ratio of 1.5 with a low axial velocity spread of 6% from 3.4-4.8 Tesla. These results are compared with a three-dimensional particle-tracing code (computer simulation technology, CST). The underlying physics for constant α will be discussed in depth.

  3. Microstructure of ZnO Thin Films Deposited by High Power Impulse Magnetron Sputtering (Postprint)

    DTIC Science & Technology

    2015-03-01

    AFRL-RX-WP-JA-2015-0185 MICROSTRUCTURE OF ZNO THIN FILMS DEPOSITED BY HIGH POWER IMPULSE MAGNETRON SPUTTERING (POSTPRINT) A. N. Reed...COVERED (From – To) 29 January 2013 – 16 February 2015 4. TITLE AND SUBTITLE MICROSTRUCTURE OF ZNO THIN FILMS DEPOSITED BY HIGH POWER IMPULSE MAGNETRON...ABSTRACT High power impulse magnetron sputtering was used to deposit thin (~100 nm) zinc oxide (ZnO) films from a ceramic ZnO target onto substrates

  4. Effect of unbalanced magnetic pull and hydraulic seal force on the vibration of large rotor-bearing systems

    NASA Astrophysics Data System (ADS)

    Song, Z.; Guo, P.; Liu, Y.

    2014-03-01

    The influence of unbalanced magnetic pull (UMP) and hydraulic seal force on the vibration of large rotor-bearing systems is studied. The UMP caused by rotor eccentricity imposes important effects on rotating machinery, especially for large generators such as water turbine generator sets, because these machines operate above their first critical speed in some instances and are supported by oil film bearings. A magnetic stiffness matrix for studying the effects of the UMP is proposed. The magnetic stiffness matrix can be generated by decomposing the expression of air gap magnetic field energy. Two vibration models are constructed using the Lagrange equation. The difference between the two models lies in the boundary support condition: one has rigid support and the other has elastic bearing support. The influence of the magnetic stiffness and elastic support on the critical speed of the rotor is studied using Lyapunov nonlinear vibration stability theory. The vibration amplitude of the rotor is calculated, taking the magnetic stiffness and horizontal centrifugal force into account. The unbalanced hydraulic seal force is produced because of the asymmetry of seal clearance. This imbalance is one of the factors that causes self-excited vibration in rotating machinery, and is as important as the UMP for large water turbine generator sets. The rotor-bearing system is supported by an oil film journal bearing, whose characteristic also impose considerable influence on vibration. On the basis of the above-mentioned conditions, a three-dimensional finite element model of the rotating system that includes the oil film journal bearing is constructed. The effect of the UMP and unbalanced hydraulic seal force is considered in the construction, and studied in relation to the magnetic parameters, seal parameters, journal bearing stiffness, and outer diameter of the rotating machine critical speed. Conclusions may benefit the dynamic design and optimized operation of large rotating

  5. An unbalanced spectra classification method based on entropy

    NASA Astrophysics Data System (ADS)

    Liu, Zhong-bao; Zhao, Wen-juan

    2017-05-01

    How to solve the problem of distinguishing the minority spectra from the majority of the spectra is quite important in astronomy. In view of this, an unbalanced spectra classification method based on entropy (USCM) is proposed in this paper to deal with the unbalanced spectra classification problem. USCM greatly improves the performances of the traditional classifiers on distinguishing the minority spectra as it takes the data distribution into consideration in the process of classification. However, its time complexity is exponential with the training size, and therefore, it can only deal with the problem of small- and medium-scale classification. How to solve the large-scale classification problem is quite important to USCM. It can be easily obtained by mathematical computation that the dual form of USCM is equivalent to the minimum enclosing ball (MEB), and core vector machine (CVM) is introduced, USCM based on CVM is proposed to deal with the large-scale classification problem. Several comparative experiments on the 4 subclasses of K-type spectra, 3 subclasses of F-type spectra and 3 subclasses of G-type spectra from Sloan Digital Sky Survey (SDSS) verify USCM and USCM based on CVM perform better than kNN (k nearest neighbor) and SVM (support vector machine) in dealing with the problem of rare spectra mining respectively on the small- and medium-scale datasets and the large-scale datasets.

  6. The Magnetron Method for the Determination of e/m for Electrons: Revisited

    ERIC Educational Resources Information Center

    Azooz, A. A.

    2007-01-01

    Additional information concerning the energy distribution function of electrons in a magnetron diode valve can be extracted. This distribution function is a manifestation of the effect of space charge at the anode. The electron energy distribution function in the magnetron is obtained from studying the variation of the anode current with the…

  7. Genotype by environment interaction and the use of unbalanced historical data for genomic selection in an international wheat breeding program

    USDA-ARS?s Scientific Manuscript database

    Genomic selection (GS) offers breeders the possibility of using historic data and unbalanced breeding trials to form training populations for predicting the performance of new lines. However, in using datasets that are unbalanced over time and space, there is increasing exposure to particular genoty...

  8. Tribological characterization of TiN coatings prepared by magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Makwana, Nishant S.; Chauhan, Kamlesh V.; Sonera, Akshay L.; Chauhan, Dharmesh B.; Dave, Divyeshkumar P.; Rawal, Sushant K.

    2018-05-01

    Titanium nitride (TiN) coating deposited on aluminium and brass pin substrates using RF reactive magnetron sputtering. The structural properties and surface morphology were characterized by X-ray diffraction (XRD), atomic force microscope (AFM) and field emission scanning electron microscope (FE-SEM). There was formation of (101) Ti2N, (110) TiN2 and (102) TiN0.30 peaks at 3.5Pa, 2Pa and 1.25Pa sputtering pressure respectively. The tribological properties of coating were inspected using pin on disc tribometer equipment. It was observed that TiN coated aluminium and brass pins demonstrated improved wear resistance than uncoated aluminium and brass pins.

  9. Primary TKA Patients with Quantifiably Balanced Soft-Tissue Achieve Significant Clinical Gains Sooner than Unbalanced Patients

    PubMed Central

    Gustke, Kenneth A.; Golladay, Gregory J.; Roche, Martin W.; Elson, Leah C.; Anderson, Christopher R.

    2014-01-01

    Although total knee arthroplasty has a high success rate, poor outcomes and early revision are associated with ligament imbalance. This multicenter evaluation was performed in order to provide 1-year followup of a previously reported group of patients who had sensor-assisted TKA, comparing the clinical outcomes of quantitatively balanced versus unbalanced patients. At 1 year, the balanced cohort scored 179.3 and 10.4 in KSS and WOMAC, respectively; the unbalanced cohort scored 156.1 and 17.9 in KSS and WOMAC (P < 0.001; P = 0.085). The average activity level scores of quantitatively balanced patients were 68.6 (corresponding to tennis, light jogging, and heavy yard work), while the average activity level of unbalanced patients was 46.7 (corresponding to light housework, and limited walking distances) (P = 0.015). Out of all confounding variables, a balanced articulation was the most significant contributing factor to improved postoperative outcomes (P < 0.001). PMID:25210632

  10. Influence of oxygen flow rate on metal-insulator transition of vanadium oxide thin films grown by RF magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Ma, Xu; Liu, Xinkun; Li, Haizhu; Zhang, Angran; Huang, Mingju

    2017-03-01

    High-quality vanadium oxide ( VO2) films have been fabricated on Si (111) substrates by radio frequency (RF) magnetron sputtering deposition method. The sheet resistance of VO2 has a significant change (close to 5 orders of magnitude) in the process of the metal-insulator phase transition (MIT). The field emission-scanning electron microscope (FE-SEM) results show the grain size of VO2 thin films is larger with the increase of oxygen flow. The X-ray diffraction (XRD) results indicate the thin films fabricated at different oxygen flow rates grow along the (011) crystalline orientation. As the oxygen flow rate increases from 3 sccm to 6 sccm, the phase transition temperature of the films reduces from 341 to 320 K, the width of the thermal hysteresis loop decreases from 32 to 9 K. The thin films fabricated in the condition of 5 sccm have a high temperature coefficient of resistance (TCR) -3.455%/K with a small resistivity of 2.795 ρ/Ω cm.

  11. Magnetron sputtered boron films and TI/B multilayer structures

    DOEpatents

    Makowiecki, Daniel M.; Jankowski, Alan F.

    1993-01-01

    A method is described for the production of thin boron and titanium/boron films by magnetron sputter deposition. The amorphous boron films contain no morphological growth features, unlike those found when thin films are prepared by various physical vapor deposition processes. Magnetron sputter deposition method requires the use of a high density crystalline boron sputter target which is prepared by hot isostatic pressing. Thin boron films prepared by this method are useful for ultra-thin band pass filters as well as the low Z element in low Z/high Z mirrors which enhance reflectivity from grazing to normal incidence.

  12. Magnetron sputtered boron films and Ti/B multilayer structures

    DOEpatents

    Makowiecki, Daniel M.; Jankowski, Alan F.

    1995-01-01

    A method is described for the production of thin boron and titanium/boron films by magnetron sputter deposition. The amorphous boron films contain no morphological growth features, unlike those found when thin films are prepared by various physical vapor deposition processes. Magnetron sputter deposition method requires the use of a high density crystalline boron sputter target which is prepared by hot isostatic pressing. Thin boron films prepared by this method are useful for ultra-thin band pass filters as well as the low Z element in low Z/high Z mirrors which enhance reflectivity from grazing to normal incidence.

  13. Magnetron sputtered boron films and TI/B multilayer structures

    DOEpatents

    Makowiecki, D.M.; Jankowski, A.F.

    1993-04-20

    A method is described for the production of thin boron and titanium/boron films by magnetron sputter deposition. The amorphous boron films contain no morphological growth features, unlike those found when thin films are prepared by various physical vapor deposition processes. Magnetron sputter deposition method requires the use of a high density crystalline boron sputter target which is prepared by hot isostatic pressing. Thin boron films prepared by this method are useful for ultra-thin band pass filters as well as the low Z element in low Z/high Z mirrors which enhance reflectivity from grazing to normal incidence.

  14. Magnetron sputtered boron films and Ti/B multilayer structures

    DOEpatents

    Makowiecki, D.M.; Jankowski, A.F.

    1995-02-14

    A method is described for the production of thin boron and titanium/boron films by magnetron sputter deposition. The amorphous boron films contain no morphological growth features, unlike those found when thin films are prepared by various physical vapor deposition processes. Magnetron sputter deposition method requires the use of a high density crystalline boron sputter target which is prepared by hot isostatic pressing. Thin boron films prepared by this method are useful for ultra-thin band pass filters as well as the low Z element in low Z/high Z mirrors which enhance reflectivity from grazing to normal incidence. 6 figs.

  15. Self-organization and self-limitation in high power impulse magnetron sputtering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Anders, Andre

    The plasma over the racetrack in high power impulse magnetron sputtering develops in traveling ionization zones. Power densities can locally reach 10{sup 9} W/m{sup 2}, which is much higher than usually reported. Ionization zones move because ions are 'evacuated' by the electric field, exposing neutrals to magnetically confined, drifting electrons. Drifting secondary electrons amplify ionization of the same ionization zone where the primary ions came from, while sputtered and outgassing atoms are supplied to the following zone(s). Strong density gradients parallel to the target disrupt electron confinement: a negative feedback mechanism that stabilizes ionization runaway.

  16. Studies of PMMA sintering foils with and without coating by magnetron sputtering Pd

    NASA Astrophysics Data System (ADS)

    Cutroneo, M.; Mackova, A.; Torrisi, L.; Vad, K.; Csik, A.; Ando', L.; Svecova, B.

    2017-09-01

    Polymethylmethacrylate thin foils were prepared by using physical and chemical processes aimed at changing certain properties. The density and the optical properties were changed obtaining clear and opaque foils. DC magnetron sputtering method was used to cover the foils with thin metallic palladium layers. The high optical absorbent foils were obtained producing microstructured PMMA microbeads with and without thin metallic coatings. Rutherford Backscattering Spectroscopy, optical investigation and microscopy were employed to characterize the prepared foils useful in the field study of laser-matter interaction.

  17. Echocardiographic definition and surgical decision-making in unbalanced atrioventricular septal defect: a Congenital Heart Surgeons' Society multiinstitutional study.

    PubMed

    Jegatheeswaran, Anusha; Pizarro, Christian; Caldarone, Christopher A; Cohen, Meryl S; Baffa, Jeanne M; Gremmels, David B; Mertens, Luc; Morell, Victor O; Williams, William G; Blackstone, Eugene H; McCrindle, Brian W; Overman, David M

    2010-09-14

    Although identification of unbalanced atrioventricular septal defect (AVSD) is obvious when extreme, exact criteria to define the limits of unbalanced are not available. We sought to validate an atrioventricular valve index (AVVI) (left atrioventricular valve area/total atrioventricular valve area, centimeters squared) as a discriminator of balanced and unbalanced forms of complete AVSD and to characterize the association of AVVI with surgical strategies and outcomes. Diagnostic echocardiograms and hospital records of 356 infants with complete AVSD at 4 Congenital Heart Surgeons' Society (CHSS) institutions (2000-2006) were reviewed and AVVI measured (n=315). Patients were classified as unbalanced if AVVI≤0.4 (right dominant) or ≥0.6 (left dominant). Surgical strategy and outcomes were examined across the range of AVVI. Competing risks analysis until the time of commitment to a surgical strategy examined 4 end states: biventricular repair (BVR), univentricular repair (UVR), pulmonary artery banding (PAB), and death before surgery. A prediction nomogram for surgical strategy based on AVVI was developed. The majority of patients had balanced AVSD (0.4unbalanced AVSD with important correlation to anatomic substrate and selected surgical strategy.

  18. Magnetron cathodes in plasma electrode pockels cells

    DOEpatents

    Rhodes, Mark A.

    1995-01-01

    Magnetron cathodes, which produce high current discharges, form greatly improved plasma electrodes on each side of an electro-optic crystal. The plasma electrode has a low pressure gas region on both sides of the crystal. When the gas is ionized, e.g., by a glow discharge in the low pressure gas, the plasma formed is a good conductor. The gas electrode acts as a highly uniform conducting electrode. Since the plasma is transparent to a high energy laser beam passing through the crystal, the plasma is transparent. A crystal exposed from two sides to such a plasma can be charged up uniformly to any desired voltage. A typical configuration utilizes helium at 50 millitorr operating. pressure and 2 kA discharge current. The magnetron cathode produces a more uniform plasma and allows a reduced operating pressure which leads to lower plasma resistivity and a more uniform charge on the crystal.

  19. Waveguide-Mode Terahertz Free Electron Lasers Driven by Magnetron-Based Microtrons

    NASA Astrophysics Data System (ADS)

    Jeong, Young Uk; Miginsky, Sergey; Gudkov, Boris; Lee, Kitae; Mun, Jungho; Shim, Gyu Il; Bae, Sangyoon; Kim, Hyun Woo; Jang, Kyu-Ha; Park, Sunjeong; Park, Seong Hee; Vinokurov, Nikolay

    2016-04-01

    We have developed small-sized terahertz free-electron lasers by using low-cost and compact microtrons combining with magnetrons as high-power RF sources. We could stabilize the bunch repetition rate by optimizing a modulator for the magnetron and by coupling the magnetron with an accelerating cavity in the microtron. By developing high-performance undulators and low-loss waveguide-mode resonators having small cross-sectional areas, we could strengthen the interaction between the electron beam and the THz wave inside the FEL resonators to achieve lasing even with low-current electron beams from the microtron. We used a parallel-plate waveguide in a planar electromagnet undulator for our first THz FEL. We try to reduce the size of the FEL resonator by combining a dielectric-coated circular waveguide and a variable-period helical undulator to realize a table-top THz FEL for applying it to the security inspection on airports.

  20. Tribological Behaviour of Ti:Ta-DLC Films Under Different Tribo-Test Conditions

    NASA Astrophysics Data System (ADS)

    Efeoglu, İhsan; Keleş, Ayşenur; Totik, Yaşar; Çiçek, Hikmet; Emine Süküroglu, Ebru

    2018-01-01

    Diamond-like carbon (DLC) films are suitable applicants for cutting tools due to their high hardness, low friction coefficient and wear rate. Doping metals in DLC films have been improved its tribological properties. In this study, titanium and tantalum doped hydrogenated DLC films were deposited by closed-field unbalanced magnetron sputtering system onto M2 high speed steels in Ar/N2/C2H2 atmosphere. The friction and wear properties of Ti:Ta-DLC film were investigated under different tribo-test conditions including in atmospheric pressure, distilled water, commercial oil and Ar atmosphere. The coated specimens were characterized by SEM and X-ray diffraction techniques. The bonding state of C-C (sp3) and C=C (sp2) were obtained with XPS. The tribological properties of Ti:Ta-DLC were investigated with pin-on-disc wear test. Hardness measurements performed by micro-indentation. Our results suggest that Ti:Ta-doped DLC film shows very dense columnar microstructure, high hardness (38.2 GPa) with low CoF (µ≈0.02) and high wear resistance (0.5E-6 mm3/Nm).

  1. High-current electron gun with a planar magnetron integrated with an explosive-emission cathode

    NASA Astrophysics Data System (ADS)

    Kiziridi, P. P.; Ozur, G. E.

    2017-05-01

    A new high-current electron gun with plasma anode and explosive-emission cathode integrated with planar pulsed powered magnetron is described. Five hundred twelve copper wires 1 mm in diameter and 15 mm in height serve as emitters. These emitters are installed on stainless steel disc (substrate) with 3-mm distance between them. Magnetron discharge plasma provides increased ion density on the periphery of plasma anode formed by high-current Penning discharge ignited within several milliseconds after starting of the magnetron discharge. The increased on the periphery ion density improves the uniformity of high-current electron beam produced in such an electron gun.

  2. Frequency noise suppression of a single mode laser with an unbalanced fiber interferometer for subnanometer interferometry.

    PubMed

    Šmíd, Radek; Čížek, Martin; Mikel, Břetislav; Číp, Ondřej

    2015-01-12

    We present a method of noise suppression of laser diodes by an unbalanced Michelson fiber interferometer. The unstabilized laser source is represented by compact planar waveguide external cavity laser module, ORIONTM (Redfern Integrated Optics, Inc.), working at 1540.57 nm with a 1.5-kHz linewidth. We built up the unbalanced Michelson interferometer with a 2.09 km-long arm based on the standard telecommunication single-mode fiber (SMF-28) spool to suppress the frequency noise by the servo-loop control by 20 dB to 40 dB within the Fourier frequency range, remaining the tuning range of the laser frequency.

  3. A cookbook for building a high-current dimpled H – magnetron source for accelerators

    DOE PAGES

    Bollinger, Daniel S.; Karns, Patrick R.; Tan, Cheng -Yang

    2015-10-30

    A high-current (>50 mA) dimpled H – magnetron source has been built at Fermilab for supplying H – beam to the entire accelerator complex. Despite many decades of expertise with slit H – magnetron sources at Fermilab, we were faced with many challenges from the dimpled H – magnetron source, which needed to be overcome in order to make it operational. Dimpled H – sources for high-energy physics are not new: Brookhaven National Laboratory has operated a dimpled H- source for more than two decades. However, the transference of that experience to Fermilab took about two years because a cookbookmore » for building this type of source did not exist and seemingly innocuous or undocumented choices had a huge impact on the success or failure for this type of source. Moreover, it is the goal of this paper to document the reasons for these choices and to present a cookbook for building and operating dimpled H – magnetron sources.« less

  4. The Development and Application of the Magnetron,

    DTIC Science & Technology

    1982-03-31

    of *medicine. The power of the magnetron used is from several tens of watts to several hundred watts. Microwave physiotherapy has been used in...clinical practice for the fast cure of arthritis , rheumatism and the subsidence of swelling. Therapeutic results have been excellent. In recent years

  5. Magnetron cathodes in plasma electrode Pockels cells

    DOEpatents

    Rhodes, M.A.

    1995-04-25

    Magnetron cathodes, which produce high current discharges, form greatly improved plasma electrodes on each side of an electro-optic crystal. The plasma electrode has a low pressure gas region on both sides of the crystal. When the gas is ionized, e.g., by a glow discharge in the low pressure gas, the plasma formed is a good conductor. The gas electrode acts as a highly uniform conducting electrode. Since the plasma is transparent to a high energy laser beam passing through the crystal, the plasma is transparent. A crystal exposed from two sides to such a plasma can be charged up uniformly to any desired voltage. A typical configuration utilizes helium at 50 millitorr operating pressure and 2 kA discharge current. The magnetron cathode produces a more uniform plasma and allows a reduced operating pressure which leads to lower plasma resistivity and a more uniform charge on the crystal. 5 figs.

  6. Radio-frequency unbalanced M-Z interferometer for wavelength interrogation of fiber Bragg grating sensors.

    PubMed

    Zhou, Jiaao; Xia, Li; Cheng, Rui; Wen, Yongqiang; Rohollahnejad, Jalal

    2016-01-15

    The optical unbalanced Mach-Zehnder interferometer (UMZI) has attracted significant interests for interrogation of FBG sensors owing to its excellent advantages in sensitivity, resolution, and demodulation speed. But this method is still limited to dynamic measurements due to its poor stability and reliability when used for quasi-static detections. Here, we propose for the first time, to the best of our knowledge, a radio-frequency unbalanced M-Z interferometer (RF-UMZI) for interrogation of FBG sensors, which, owing to its operation in an incoherent rather than a coherent regime, provides an ideal solution for the existing stability problem of the conventional UMZI, with remarkable features of adjustable resolution and potentially extremely high sensitivity. A dispersion compensation fiber (DCF) and single-mode fiber (SMF) with a small length difference are served as the two unbalanced arms of the RF interferometer. The induced differential chromatic dispersion transfers the wavelength shift of the FBG to the change of the RF phase difference between the two interferometric carriers, which ultimately leads to the variation of the RF signal intensity. An interrogation of a strain-turned FBG was accomplished and a maximum sensitivity of 0.00835  a.u./με was obtained, which can easily be further improved by more than two orders of magnitude through various fiber dispersion components. Finally, the stability of the interrogation was tested.

  7. Improved Magnetron Stability and Reduced Noise in Efficient Transmitters for Superconducting Accelerators

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kazakevich, G.; Johnson, R.; Lebedev, V.

    State of the art high-current superconducting accelerators require efficient RF sources with a fast dynamic phase and power control. This allows for compensation of the phase and amplitude deviations of the accelerating voltage in the Superconducting RF (SRF) cavities caused by microphonics, etc. Efficient magnetron transmitters with fast phase and power control are attractive RF sources for this application. They are more cost effective than traditional RF sources such as klystrons, IOTs and solid-state amplifiers used with large scale accelerator projects. However, unlike traditional RF sources, controlled magnetrons operate as forced oscillators. Study of the impact of the controlling signalmore » on magnetron stability, noise and efficiency is therefore important. This paper discusses experiments with 2.45 GHz, 1 kW tubes and verifies our analytical model which is based on the charge drift approximation.« less

  8. High performance thin film transistor with ZnO channel layer deposited by DC magnetron sputtering.

    PubMed

    Moon, Yeon-Keon; Moon, Dae-Yong; Lee, Sang-Ho; Jeong, Chang-Oh; Park, Jong-Wan

    2008-09-01

    Research in large area electronics, especially for low-temperature plastic substrates, focuses commonly on limitations of the semiconductor in thin film transistors (TFTs), in particular its low mobility. ZnO is an emerging example of a semiconductor material for TFTs that can have high mobility, while a-Si and organic semiconductors have low mobility (<1 cm2/Vs). ZnO-based TFTs have achieved high mobility, along with low-voltage operation low off-state current, and low gate leakage current. In general, ZnO thin films for the channel layer of TFTs are deposited with RF magnetron sputtering methods. On the other hand, we studied ZnO thin films deposited with DC magnetron sputtering for the channel layer of TFTs. After analyzing the basic physical and chemical properties of ZnO thin films, we fabricated a TFT-unit cell using ZnO thin films for the channel layer. The field effect mobility (micro(sat)) of 1.8 cm2/Vs and threshold voltage (Vth) of -0.7 V were obtained.

  9. Valve-sparing reimplantation for neoaortic root dilatation and regurgitation with an unbalanced cusp after the arterial switch operation.

    PubMed

    Yoneyama, Fumiya; Okamura, Toru; Harada, Yorikazu; Okita, Yutaka

    2018-02-01

    A 13-year-old male presented with neoaortic root dilatation and severe aortic valve regurgitation 13 years following an arterial switch operation. The valve cusps were unbalanced due to an enlarged non-coronary cusp. A valve-sparing reimplantation with a cusp plication was performed which resulted in a competent valve with trivial regurgitation. Thus, even in an unbalanced cusp, valve-sparing reimplantation can be used for neoaortic root dilatation and valve regurgitation after an arterial switch operation. © 2018 Wiley Periodicals, Inc.

  10. Frequency Noise Suppression of a Single Mode Laser with an Unbalanced Fiber Interferometer for Subnanometer Interferometry

    PubMed Central

    Šmíd, Radek; Čížek, Martin; Mikel, Břetislav; Číp, Ondřej

    2015-01-01

    We present a method of noise suppression of laser diodes by an unbalanced Michelson fiber interferometer. The unstabilized laser source is represented by compact planar waveguide external cavity laser module, ORIONTM (Redfern Integrated Optics, Inc.), working at 1540.57 nm with a 1.5-kHz linewidth. We built up the unbalanced Michelson interferometer with a 2.09 km-long arm based on the standard telecommunication single-mode fiber (SMF-28) spool to suppress the frequency noise by the servo-loop control by 20 dB to 40 dB within the Fourier frequency range, remaining the tuning range of the laser frequency. PMID:25587980

  11. Closed-field capacitive liquid level sensor

    DOEpatents

    Kronberg, James W.

    1998-01-01

    A liquid level sensor based on a closed field circuit comprises a ring oscillator using a symmetrical array of plate units that creates a displacement current. The displacement current varies as a function of the proximity of a liquid to the plate units. The ring oscillator circuit produces an output signal with a frequency inversely proportional to the presence of a liquid. A continuous liquid level sensing device and a two point sensing device are both proposed sensing arrangements. A second set of plates may be located inside of the probe housing relative to the sensing plate units. The second set of plates prevent any interference between the sensing plate units.

  12. Closed-field capacitive liquid level sensor

    DOEpatents

    Kronberg, J.W.

    1995-01-01

    A liquid level sensor based on a closed field circuit comprises a ring oscillator using a symmetrical array of plate units that creates a displacement current. The displacement current varies as a function of the proximity of a liquid to the plate units. The ring oscillator circuit produces an output signal with a frequency inversely proportional to the presence of a liquid. A continuous liquid level sensing device and a two point sensing device are both proposed sensing arrangements. A second set of plates may be located inside of the probe housing relative to the sensing plate units. The second set of plates prevent any interference between the sensing plate units.

  13. Is This Object Balanced or Unbalanced? Judgments Are on the Safe Side

    ERIC Educational Resources Information Center

    Samuel, Francoise; Kerzel, Dirk

    2011-01-01

    Do we perceive correctly whether a 2-D object is balanced or unbalanced? What would be the cause of biased equilibrium judgments? In two psychometric studies, we varied independently the characteristics of the objects and the equilibrium states. First, we observed that observers were excessively sensitive to the eccentricity of the object top.…

  14. Characterization and optimization of the magnetron directional amplifier

    NASA Astrophysics Data System (ADS)

    Hatfield, Michael Craig

    Many applications of microwave wireless power transmission (WPT) are dependent upon a high-powered electronically-steerable phased array composed of many radiating modules. The phase output from the high-gain amplifier in each module must be accurately controlled if the beam is to be properly steered. A highly reliable, rugged, and inexpensive design is essential for making WPT applications practical. A conventional microwave oven magnetron may be combined with a ferrite circulator and other external circuitry to create such a system. By converting it into a two-port amplifier, the magnetron is capable of delivering at least 30 dB of power gain while remaining phase-locked to the input signal over a wide frequency range. The use of the magnetron in this manner is referred to as a MDA (Magnetron Directional Amplifier). The MDA may be integrated with an inexpensive slotted waveguide array (SWA) antenna to form the Electronically-Steerable Phased Array Module (ESPAM). The ESPAM provides a building block approach to creating phased arrays for WPT. The size and shape of the phased array may be tailored to satisfy a diverse range of applications. This study provided an in depth examination into the capabilities of the MDA/ESPAM. The basic behavior of the MDA was already understood, as well as its potential applicability to WPT. The primary objective of this effort was to quantify how well the MDA could perform in this capacity. Subordinate tasks included characterizing the MDA behavior in terms of its system inputs, optimizing its performance, performing sensitivity analyses, and identifying operating limitations. A secondary portion of this study examined the suitability of the ESPAM in satisfying system requirements for the solar power satellite (SPS). Supporting tasks included an analysis of SPS requirements, modeling of the SWA antenna, and the demonstration of a simplified phased array constructed of ESPAM elements. The MDA/ESPAM is well suited for use as an

  15. Alfven's critical ionization velocity observed in high power impulse magnetron sputtering discharges

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Brenning, N.; Lundin, D.

    2012-09-15

    Azimuthally rotating dense plasma structures, spokes, have recently been detected in several high power impulse magnetron sputtering (HiPIMS) devices used for thin film deposition and surface treatment, and are thought to be important for plasma buildup, energizing of electrons, as well as cross-B transport of charged particles. In this work, the drift velocities of these spokes are shown to be strongly correlated with the critical ionization velocity, CIV, proposed by Alfven. It is proposed as the most promising approach in combining the CIV and HiPIMS research fields is to focus on the role of spokes in the process of electronmore » energization.« less

  16. Plasma ``anti-assistance'' and ``self-assistance'' to high power impulse magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Anders, André; Yushkov, Georgy Yu.

    2009-04-01

    A plasma assistance system was investigated with the goal to operate high power impulse magnetron sputtering (HiPIMS) at lower pressure than usual, thereby to enhance the utilization of the ballistic atoms and ions with high kinetic energy in the film growth process. Gas plasma flow from a constricted plasma source was aimed at the magnetron target. Contrary to initial expectations, such plasma assistance turned out to be contraproductive because it led to the extinction of the magnetron discharge. The effect can be explained by gas rarefaction. A better method of reducing the necessary gas pressure is operation at relatively high pulse repetition rates where the afterglow plasma of one pulse assists in the development of the next pulse. Here we show that this method, known from medium-frequency (MF) pulsed sputtering, is also very important at the much lower pulse repetition rates of HiPIMS. A minimum in the possible operational pressure is found in the frequency region between HiPIMS and MF pulsed sputtering.

  17. Innovative Inverted Magnetron Experiments and Theory

    DTIC Science & Technology

    2015-06-01

    and characterized the Recirculating Planar Magnetron (RPM), a new type of High Power Microwave (HPM) device. Researchers have simulated the operation... power extraction is desired. In simulation, the RPM-CACE was up to 70% efficient, producing peak microwave powers of 420 MW. 15. SUBJECT TERMS High ...type of High Power Microwave (HPM) device. Using HFSS, MAGIC, and ICEPIC, researchers have simulated the operation of the device in both a

  18. A Parallel Biological Optimization Algorithm to Solve the Unbalanced Assignment Problem Based on DNA Molecular Computing.

    PubMed

    Wang, Zhaocai; Pu, Jun; Cao, Liling; Tan, Jian

    2015-10-23

    The unbalanced assignment problem (UAP) is to optimally resolve the problem of assigning n jobs to m individuals (m < n), such that minimum cost or maximum profit obtained. It is a vitally important Non-deterministic Polynomial (NP) complete problem in operation management and applied mathematics, having numerous real life applications. In this paper, we present a new parallel DNA algorithm for solving the unbalanced assignment problem using DNA molecular operations. We reasonably design flexible-length DNA strands representing different jobs and individuals, take appropriate steps, and get the solutions of the UAP in the proper length range and O(mn) time. We extend the application of DNA molecular operations and simultaneity to simplify the complexity of the computation.

  19. Closed-field capacitive liquid level sensor

    DOEpatents

    Kronberg, J.W.

    1998-03-03

    A liquid level sensor based on a closed field circuit comprises a ring oscillator using a symmetrical array of plate units that creates a displacement current. The displacement current varies as a function of the proximity of a liquid to the plate units. The ring oscillator circuit produces an output signal with a frequency inversely proportional to the presence of a liquid. A continuous liquid level sensing device and a two point sensing device are both proposed sensing arrangements. A second set of plates may be located inside of the probe housing relative to the sensing plate units. The second set of plates prevent any interference between the sensing plate units. 12 figs.

  20. Generation of vortex array laser beams with Dove prism embedded unbalanced Mach-Zehnder interferometer

    NASA Astrophysics Data System (ADS)

    Chu, Shu-Chun

    2009-02-01

    This paper introduces a scheme for generation of vortex laser beams from a solid-state laser with off-axis laser-diode pumping. The proposed system consists of a Dove prism embedded in an unbalanced Mach-Zehnder interferometer configuration. This configuration allows controlled construction of p × p vortex array beams from Ince-Gaussian modes, IGep,p modes. An incident IGe p,p laser beam of variety order p can easily be generated from an end-pumped solid-state laser with an off-axis pumping mechanism. This study simulates this type of vortex array laser beam generation and discusses beam propagation effects. The formation of ordered transverse emission patterns have applications in a variety of areas such as optical data storage, distribution, and processing that exploit the robustness of soliton and vortex fields and optical manipulations of small particles and atoms in the featured intensity distribution.

  1. SERS spectra of pyridine adsorbed on nickel film prepared by magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Li, Daoyong; Ouyang, Yu; Chen, Li; Cao, Weiran; Shi, Shaohua

    2011-02-01

    As a repeating well and cheaper enhancement substrate, the nickel film was fabricated with magnetron sputtering coating instrument. Surface enhanced Raman spectra (SERS) of pyridine adsorbed on this nickel film are compared with the experimental values of gaseous pyridine, the theoretical value of pyridine solution listed in other literatures and our method is better than electro-chemical etching electrode method for large scale preparation. The enhancement factor of the nickel film is calculated and the result indicates that magnetron sputtering coating technology is feasible for obtaining good SERS active surface.

  2. Non-polynomial closed string field theory: loops and conformal maps

    NASA Astrophysics Data System (ADS)

    Hua, Long; Kaku, Michio

    1990-11-01

    Recently, we proposed the complete classical action for the non-polynomial closed string field theory, which succesfully reproduced all closed string tree amplitudes. (The action was simultaneously proposed by the Kyoto group). In this paper, we analyze the structure of the theory. We (a) compute the explicit conformal map for all g-loop, p-puncture diagrams, (b) compute all one-loop, two-puncture maps in terms of hyper-elliptic functions, and (c) analyze their modular structure. We analyze, but do not resolve, the question of modular invariance.

  3. Dynamic effects of restoring footpoint symmetry on closed magnetic field lines

    NASA Astrophysics Data System (ADS)

    Reistad, J. P.; Østgaard, N.; Tenfjord, P.; Laundal, K. M.; Snekvik, K.; Haaland, S.; Milan, S. E.; Oksavik, K.; Frey, H. U.; Grocott, A.

    2016-05-01

    Here we present an event where simultaneous global imaging of the aurora from both hemispheres reveals a large longitudinal shift of the nightside aurora of about 3 h, being the largest relative shift reported on from conjugate auroral imaging. This is interpreted as evidence of closed field lines having very asymmetric footpoints associated with the persistent positive y component of the interplanetary magnetic field before and during the event. At the same time, the Super Dual Auroral Radar Network observes the ionospheric nightside convection throat region in both hemispheres. The radar data indicate faster convection toward the dayside in the dusk cell in the Southern Hemisphere compared to its conjugate region. We interpret this as a signature of a process acting to restore symmetry of the displaced closed magnetic field lines resulting in flux tubes moving faster along the banana cell than the conjugate orange cell. The event is analyzed with emphasis on Birkeland currents (BC) associated with this restoring process, as recently described by Tenfjord et al. (2015). Using data from the Active Magnetosphere and Planetary Electrodynamics Response Experiment (AMPERE) during the same conditions as the presented event, the large-scale BC pattern associated with the event is presented. It shows the expected influence of the process of restoring symmetry on BCs. We therefore suggest that these observations should be recognized as being a result of the dynamic effects of restoring footpoint symmetry on closed field lines in the nightside.

  4. A Magnetron Sputter Deposition System for the Development of Multilayer X-Ray Optics

    NASA Technical Reports Server (NTRS)

    Broadway, David; Ramsey, Brian; Gubarev, Mikhail

    2014-01-01

    The proposal objective is to establish the capability to deposit multilayer structures for x-ray, neutron, and EUV optic applications through the development of a magnetron sputtering deposition system. A specific goal of this endeavor is to combine multilayer deposition technology with the replication process in order to enhance the MSFC's position as a world leader in the design of innovative X-ray instrumentation through the development of full shell replicated multilayer optics. The development of multilayer structures is absolutely necessary in order to advance the field of X-ray astronomy by pushing the limit for observing the universe to ever increasing photon energies (i. e. up to 200 keV or higher); well beyond Chandra (approx. 10 keV) and NuStar's (approx. 75 keV) capability. The addition of multilayer technology would significantly enhance the X-ray optics capability at MSFC and allow NASA to maintain its world leadership position in the development, fabrication and design of innovative X-ray instrumentation which would be the first of its kind by combining multilayer technology with the mirror replication process. This marriage of these technologies would allow astronomers to see the universe in a new light by pushing to higher energies that are out of reach with today's instruments.To this aim, a magnetron vacum sputter deposition system for the deposition of novel multilayer thin film X-ray optics is proposed. A significant secondary use of the vacuum deposition system includes the capability to fabricate multilayers for applications in the field of EUV optics for solar physics, neutron optics, and X-ray optics for a broad range of applications including medical imaging.

  5. A Magnetron Sputter Deposition System for the Development of X-Ray Multilayer Optics

    NASA Technical Reports Server (NTRS)

    Broadway, David

    2015-01-01

    The project objective is to establish the capability to deposit multilayer structures for x-ray, neutron, and extreme ultraviolet (EUV) optic applications through the development of a magnetron sputtering deposition system. A specific goal of this endeavor is to combine multilayer deposition technology with the replication process in order to enhance NASA Marshall Space Flight Center's (MSFC's) position as a world leader in the design of innovative x-ray instrumentation through the development of full shell replicated multilayer optics. The development of multilayer structures are absolutely necessary in order to advance the field of x-ray astronomy by pushing the limit for observing the universe to ever-increasing photon energies (i.e., up to 200 keV or higher), well beyond Chandra's (approx.10 keV) and NuStar's (approx.75 keV) capability. The addition of multilayer technology would significantly enhance the x-ray optics capability at MSFC and allow NASA to maintain its world leadership position in the development, fabrication, and design of innovative x-ray instrumentation, which would be the first of its kind by combining multilayer technology with the mirror replication process. This marriage of these technologies would allow astronomers to see the universe in a new light by pushing to higher energies that are out of reach with today's instruments. To this aim, a magnetron vacuum sputter deposition system for the deposition of novel multilayer thin film x-ray optics is proposed. A significant secondary use of the vacuum deposition system includes the capability to fabricate multilayers for applications in the field of EUV optics for solar physics, neutron optics, and x-ray optics for a broad range of applications including medical imaging.

  6. On open and closed field line regions in Tsyganenko's field model and their possible associations with horse collar auroras

    NASA Technical Reports Server (NTRS)

    Birn, J.; Hones, E. W., Jr.; Craven, J. D.; Frank, L. A.; Elphinstone, R. D.; Stern, D. P.

    1991-01-01

    The boundary between open and closed field lines is investigated in the empirical Tsyganenko (1987) magnetic field model. All field lines extending to distances beyond -70 R(E), the tailward velocity limit of the Tsyganenko model are defined as open, while all other field lines, which cross the equatorial plane earthward of -70 R(E) and are connected with the earth at both ends, are assumed closed. It is found that this boundary at the surface of the earth, identified as the polar cap boundary, can exhibit the arrowhead shape, pointed toward the sun, which is found in horse collar auroras. For increasing activity levels, the polar cap increases in area and becomes rounder, so that the arrowhead shape is less pronounced. The presence of a net B(y) component can also lead to considerable rounding of the open flux region. The arrowhead shape is found to be closely associated with the increase of B(z) from the midnight region to the flanks of the tail, consistent with a similar increase of the plasma sheet thickness.

  7. A Parallel Biological Optimization Algorithm to Solve the Unbalanced Assignment Problem Based on DNA Molecular Computing

    PubMed Central

    Wang, Zhaocai; Pu, Jun; Cao, Liling; Tan, Jian

    2015-01-01

    The unbalanced assignment problem (UAP) is to optimally resolve the problem of assigning n jobs to m individuals (m < n), such that minimum cost or maximum profit obtained. It is a vitally important Non-deterministic Polynomial (NP) complete problem in operation management and applied mathematics, having numerous real life applications. In this paper, we present a new parallel DNA algorithm for solving the unbalanced assignment problem using DNA molecular operations. We reasonably design flexible-length DNA strands representing different jobs and individuals, take appropriate steps, and get the solutions of the UAP in the proper length range and O(mn) time. We extend the application of DNA molecular operations and simultaneity to simplify the complexity of the computation. PMID:26512650

  8. Langmuir Probe Measurements in a Grid-Assisted Magnetron Sputtering System

    NASA Astrophysics Data System (ADS)

    Sagás, Julio César; Pessoa, Rodrigo Sávio; Maciel, Homero Santiago

    2018-02-01

    The grid-assisted magnetron sputtering is a variation of the magnetron sputtering commonly used for thin film deposition. In this work, Langmuir probe measurements were performed in such a system by using the grid under two basic and practical electrical conditions, i.e., floating and grounded. The results show that grounding the grid leads to an enhancement of the plasma confinement and to increases in both floating and plasma potential, as inferred from the probe characteristics. The grounded grid drains electrons from the plasma, acting as an auxiliary anode and reducing the plasma diffusion toward the chamber walls. For the same discharge current, the improved confinement results in a lower electron temperature when compared to floating condition, although the electron densities are comparable in both cases.

  9. Microwave beamed power technology improvement. [magnetrons and slotted waveguide arrays

    NASA Technical Reports Server (NTRS)

    Brown, W. C.

    1980-01-01

    The magnetron directional amplifier was tested for (1) phase shift and power output as a function of gain, anode current, and anode voltage, (2) background noise and harmonics in the output, (3) long life potential of the magnetron cathode, and (4) high operational efficiency. Examples of results were an adequate range of current and voltage over which 20 dB of amplification could be obtained, spectral noise density 155 dB below the carrier, 81.7% overall efficiency, and potential cathode life of 50 years in a design for solar power satellite use. A fabrication method was used to fabricate a 64 slot, 30 in square slotted waveguide array module from 0.020 in thick aluminum sheet. The test results on the array are discussed.

  10. Fabrication and characterization of self-folding thermoplastic sheets using unbalanced thermal shrinkage.

    PubMed

    Danielson, Christian; Mehrnezhad, Ali; YekrangSafakar, Ashkan; Park, Kidong

    2017-06-14

    Self-folding or micro-origami technologies are actively investigated as a novel manufacturing process to fabricate three-dimensional macro/micro-structures. In this paper, we present a simple process to produce a self-folding structure with a biaxially oriented polystyrene sheet (BOPS) or Shrinky Dinks. A BOPS sheet is known to shrink to one-third of its original size in plane, when it is heated above 160 °C. A grid pattern is engraved on one side of the BOPS film with a laser engraver to decrease the thermal shrinkage of the engraved side. The thermal shrinkage of the non-engraved side remains the same and this unbalanced thermal shrinkage causes folding of the structure as the structure shrinks at high temperature. We investigated the self-folding mechanism and characterized how the grid geometry, the grid size, and the power of the laser engraver affect the bending curvature. The developed fabrication process to locally modulate thermomechanical properties of the material by engraving the grid pattern and the demonstrated design methodology to harness the unbalanced thermal shrinkage can be applied to develop complicated self-folding macro/micro structures.

  11. Theory of injection locking and rapid start-up of magnetrons, and effects of manufacturing errors in terahertz traveling wave tubes

    NASA Astrophysics Data System (ADS)

    Pengvanich, Phongphaeth

    In this thesis, several contemporary issues on coherent radiation sources are examined. They include the fast startup and the injection locking of microwave magnetrons, and the effects of random manufacturing errors on phase and small signal gain of terahertz traveling wave amplifiers. In response to the rapid startup and low noise magnetron experiments performed at the University of Michigan that employed periodic azimuthal perturbations in the axial magnetic field, a systematic study of single particle orbits is performed for a crossed electric and periodic magnetic field. A parametric instability in the orbits, which brings a fraction of the electrons from the cathode toward the anode, is discovered. This offers an explanation of the rapid startup observed in the experiments. A phase-locking model has been constructed from circuit theory to qualitatively explain various regimes observed in kilowatt magnetron injection-locking experiments, which were performed at the University of Michigan. These experiments utilize two continuous-wave magnetrons; one functions as an oscillator and the other as a driver. Time and frequency domain solutions are developed from the model, allowing investigations into growth, saturation, and frequency response of the output. The model qualitatively recovers many of the phase-locking frequency characteristics observed in the experiments. Effects of frequency chirp and frequency perturbation on the phase and lockability have also been quantified. Development of traveling wave amplifier operating at terahertz is a subject of current interest. The small circuit size has prompted a statistical analysis of the effects of random fabrication errors on phase and small signal gain of these amplifiers. The small signal theory is treated with a continuum model in which the electron beam is monoenergetic. Circuit perturbations that vary randomly along the beam axis are introduced through the dimensionless Pierce parameters describing the beam

  12. Axial Structure of High-Vacuum Planar Magnetron Discharge Space

    NASA Astrophysics Data System (ADS)

    Miura, Tsutomu

    1999-09-01

    The spatial structure of high-vacuum planar magnetron discharge is theoretically investigated taking into account the electron confinement. The boundary xes of the electron confinement region depends on BA with Ea/BA as the parameter (BA: the magnetic flux density at the anode, Ea: the average electric field strength). The location at which the frequency of ionization events takes the maximum is expressed as CnNxiep (CnN: a factor related to the electron density distribution, xiep: the distance of the location from the cathode at which the ionization is most efficient). With increasing Ea and BA at a fixed Ea/BA, the density of the confined energetic electrons increases. With increasing Ea, the region where ionization is efficient shifts to the cathode side to give a high efficiency of the magnet. The boundary xes as determined by the probe method agreed with the theoretical prediction.

  13. Quantum field theory in spaces with closed timelike curves

    NASA Astrophysics Data System (ADS)

    Boulware, David G.

    1992-11-01

    Gott spacetime has closed timelike curves, but no locally anomalous stress energy. A complete orthonormal set of eigenfunctions of the wave operator is found in the special case of a spacetime in which the total deficit angle is 2π. A scalar quantum field theory is constructed using these eigenfunctions. The resultant interacting quantum field theory is not unitary because the field operators can create real, on-shell, particles in the noncausal region. These particles propagate for finite proper time accumulating an arbitrary phase before being annihilated at the same spacetime point as that at which they were created. As a result, the effective potential within the noncausal region is complex, and probability is not conserved. The stress tensor of the scalar field is evaluated in the neighborhood of the Cauchy horizon; in the case of a sufficiently small Compton wavelength of the field, the stress tensor is regular and cannot prevent the formation of the Cauchy horizon.

  14. Usefulness of left ventricular inflow index to predict successful biventricular repair in right-dominant unbalanced atrioventricular canal.

    PubMed

    Szwast, Anita L; Marino, Bradley S; Rychik, Jack; Gaynor, James William; Spray, Thomas L; Cohen, Meryl S

    2011-01-01

    The outcome of biventricular (BV) repair for right-dominant unbalanced atrioventricular canal has remained poor, because it is difficult to predict left ventricular (LV) adequacy before surgery. Our aim was to determine whether preoperative echocardiographic parameters, specifically analysis of color inflow into the LV, would predict survival after BV repair in patients with right-dominant unbalanced atrioventricular canal. Subjects with right-dominant unbalanced atrioventricular canal diagnosed from 1994 to 2007 were included. The echocardiographic parameters were analyzed blinded to the palliation strategy and survival. The LV inflow index (LVII) was calculated as the secondary color inflow diameter indexed to the left atrioventricular valve (AVV) annulus diameter. Univariate analysis, survival analysis, and multivariate modeling with stepwise logistic regression were performed. Of the 45 subjects, 23 (51%) underwent single ventricle (SV) palliation and 22 (49%) underwent BV repair. Of the 23 who underwent SV palliation, 15 (65%) survived compared to 18 (82%) of 22 who underwent BV repair (p = 0.34). In the BV group, a greater LVII predicted survival (R2 = 0.46, p = 0.03). No subjects with a LVII <0.5 survived BV repair. Mortality in the BV group was associated with younger age at initial surgery (p <0.01) and abnormal left AVV morphology (p = 0.02). Of the BV subjects with a patent ductus arteriosus at the initial operation (n = 11), the nonsurvivors were more likely to have retrograde flow in the transverse arch (p <0.01). In the BV group, reoperation within 30 days of the initial repair was strongly associated with mortality (p <0.01). In conclusion, in cases of mild or moderate LV hypoplasia, a greater LVII predicted survival after BV repair in patients with right-dominant unbalanced atrioventricular canal. We propose incorporation of the LVII into the echocardiographic assessment of these patients. Copyright © 2011 Elsevier Inc. All rights reserved.

  15. Deposition and characterization of magnetron sputtered bcc tantalum

    NASA Astrophysics Data System (ADS)

    Patel, Anamika

    under increasing loads revealed high critical load values for failure (>15 N) for the bcc coatings versus the low load values (<9 N) for the beta coatings. The coating deposited on TaN interlayers on sputter-etched steel had better adhesion than those on steel surface without sputter etching. The results for this work have demonstrated that by controlling the various process parameters of do magnetron sputtering, high quality bcc Ta coatings of multi-micron thickness with excellent adhesion to steel can be made. An important contribution of this dissertation is in the enhancing an understanding of this process. The impact of this research will be in a number of fields where superior protective castings are needed. These include military applications, electronic components, chemical processing, and others.

  16. MHD Stability of Axisymmetric Plasmas In Closed Line Magnetic Fields

    NASA Astrophysics Data System (ADS)

    Simakov, Andrei N.; Catto, Peter J.; Ramos, Jesus J.; Hastie, R. J.

    2003-04-01

    The stability of axisymmetric plasmas confined by closed poloidal magnetic field lines is considered. The results are relevant to plasmas in the dipolar fields of stars and planets, as well as the Levitated Dipole Experiment, multipoles, Z pinches and field reversed configurations. The ideal MHD energy principle is employed to study stability of pressure driven Alfvén modes. A point dipole is considered in detail to demonstrate that equilibria exist, which are MHD stable for arbitrary beta. Effects of sound waves and plasma resistivity are investigated next for point dipole equilibria by means of resistive MHD theory.

  17. Precision vector control of a superconducting RF cavity driven by an injection locked magnetron

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Chase, Brian; Pasquinelli, Ralph; Cullerton, Ed

    The technique presented in this paper enables the regulation of both radio frequency amplitude and phase in narrow band devices such as a Superconducting RF (SRF) cavity driven by constant power output devices i.e. magnetrons [1]. The ability to use low cost high efficiency magnetrons for accelerator RF power systems, with tight vector regulation, presents a substantial cost savings in both construction and operating costs - compared to current RF power system technology. An operating CW system at 2.45 GHz has been experimentally developed. Vector control of an injection locked magnetron has been extensively tested and characterized with a SRFmore » cavity as the load. Amplitude dynamic range of 30 dB, amplitude stability of 0.3% r.m.s, and phase stability of 0.26 degrees r.m.s. has been demonstrated.« less

  18. Precision vector control of a superconducting RF cavity driven by an injection locked magnetron

    DOE PAGES

    Chase, Brian; Pasquinelli, Ralph; Cullerton, Ed; ...

    2015-03-01

    The technique presented in this paper enables the regulation of both radio frequency amplitude and phase in narrow band devices such as a Superconducting RF (SRF) cavity driven by constant power output devices i.e. magnetrons [1]. The ability to use low cost high efficiency magnetrons for accelerator RF power systems, with tight vector regulation, presents a substantial cost savings in both construction and operating costs - compared to current RF power system technology. An operating CW system at 2.45 GHz has been experimentally developed. Vector control of an injection locked magnetron has been extensively tested and characterized with a SRFmore » cavity as the load. Amplitude dynamic range of 30 dB, amplitude stability of 0.3% r.m.s, and phase stability of 0.26 degrees r.m.s. has been demonstrated.« less

  19. Computational model for calculating the dynamical behaviour of generators caused by unbalanced magnetic pull and experimental validation

    NASA Astrophysics Data System (ADS)

    Pennacchi, Paolo

    2008-04-01

    The modelling of the unbalanced magnetic pull (UMP) in generators and the experimental validation of the proposed method are presented in this paper. The UMP is one of the most remarkable effects of electromechanical interactions in rotating machinery. As a consequence of the rotor eccentricity, the imbalance of the electromagnetic forces acting between rotor and stator generates a net radial force. This phenomenon can be avoided by means of a careful assembly and manufacture in small and stiff machines, like electrical motors. On the contrary, the eccentricity of the active part of the rotor with respect to the stator is unavoidable in big generators of power plants, because they operate above their first critical speed and are supported by oil-film bearings. In the first part of the paper, a method aimed to calculate the UMP force is described. This model is more general than those available in literature, which are limited to circular orbits. The model is based on the actual position of the rotor inside the stator, therefore on the actual air-gap distribution, regardless of the orbit type. The closed form of the nonlinear UMP force components is presented. In the second part, the experimental validation of the proposed model is presented. The dynamical behaviour in the time domain of a steam turbo-generator of a power plant is considered and it is shown that the model is able to reproduce the dynamical effects due to the excitation of the magnetic field in the generator.

  20. TOPICAL REVIEW: Physics and phenomena in pulsed magnetrons: an overview

    NASA Astrophysics Data System (ADS)

    Bradley, J. W.; Welzel, T.

    2009-05-01

    This paper reviews the contribution made to the observation and understanding of the basic physical processes occurring in an important type of magnetized low-pressure plasma discharge, the pulsed magnetron. In industry, these plasma sources are operated typically in reactive mode where a cathode is sputtered in the presence of both chemically reactive and noble gases typically with the power modulated in the mid-frequency (5-350 kHz) range. In this review, we concentrate mostly, however, on physics-based studies carried out on magnetron systems operated in argon. This simplifies the physical-chemical processes occurring and makes interpretation of the observations somewhat easier. Since their first recorded use in 1993 there have been more than 300 peer-reviewed paper publications concerned with pulsed magnetrons, dealing wholly or in part with fundamental observations and basic studies. The fundamentals of these plasmas and the relationship between the plasma parameters and thin film quality regularly have whole sessions at international conferences devoted to them; however, since many different types of magnetron geometries have been used worldwide with different operating parameters the important results are often difficult to tease out. For example, we find the detailed observations of the plasma parameter (particle density and temperature) evolution from experiment to experiment are at best difficult to compare and at worst contradictory. We review in turn five major areas of studies which are addressed in the literature and try to draw out the major results. These areas are: fast electron generation, bulk plasma heating, short and long-term plasma parameter rise and decay rates, plasma potential modulation and transient phenomena. The influence of these phenomena on the ion energy and ion energy flux at the substrate is discussed. This review, although not exhaustive, will serve as a useful guide for more in-depth investigations using the referenced

  1. Reactive high power impulse magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Gudmundsson, J. T.; Magnus, F.; Tryggvason, T. K.; Sveinsson, O. B.; Olafsson, S.

    2012-10-01

    Here we discuss reactive high power impulse magnetron sputtering sputtering (HiPIMS) [1] of Ti target in an Ar/N2 and Ar/O2 atmosphere. The discharge current waveform is highly dependent on both the pulse repetition frequency and discharge voltage. The discharge current increases with decreasing frequency or voltage. This we attribute to an increase in the secondary electron emission yield during the self-sputtering phase of the pulse, as nitride [2] or oxide [3] forms on the target. We also discuss the growth of TiN films on SiO2 at temperatures of 22-600 ^oC. The HiPIMS process produces denser films at lower growth temperature and the surface is much smoother and have a significantly lower resistivity than dc magnetron sputtered films on SiO2 at all growth temperatures due to reduced grain boundary scattering [4].[4pt] [1] J. T. Gudmundsson, N. Brenning, D. Lundin and U. Helmersson, J. Vac. Sci. Technol. A, 30 030801 (2012)[0pt] [2] F. Magnus, O. B. Sveinsson, S. Olafsson and J. T. Gudmundsson, J. Appl. Phys., 110 083306 (2011)[0pt] [3] F. Magnus, T. K. Tryggvason, S. Olafsson and J. T. Gudmundsson, J. Vac. Sci. Technol., submitted 2012[0pt] [4] F. Magnus, A. S. Ingason, S. Olafsson and J. T. Gudmundsson, IEEE Elec. Dev. Lett., accepted 2012

  2. Magnetron sputtered boron films for increasing hardness of a metal surface

    DOEpatents

    Makowiecki, Daniel M [Livermore, CA; Jankowski, Alan F [Livermore, CA

    2003-05-27

    A method is described for the production of thin boron and titanium/boron films by magnetron sputter deposition. The amorphous boron films contain no morphological growth features, unlike those found when thin films are prepared by various physical vapor deposition processes. Magnetron sputter deposition method requires the use of a high density crystalline boron sputter target which is prepared by hot isostatic pressing. Thin boron films prepared by this method are useful for producing hardened surfaces, surfacing machine tools, etc. and for ultra-thin band pass filters as well as the low Z element in low Z/high Z optical components, such as mirrors which enhance reflectivity from grazing to normal incidence.

  3. High power impulse magnetron sputtering discharges: Instabilities and plasma self-organization

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ehiasarian, A. P.; New, R.; Hecimovic, A.

    We report on instabilities in high power impulse magnetron sputtering plasmas which are likely to be of the generalized drift wave type. They are characterized by well defined regions of high and low plasma emissivity along the racetrack of the magnetron and cause periodic shifts in floating potential. The azimuthal mode number m depends on plasma current, plasma density, and gas pressure. The structures rotate in E-vectorxB-vector direction at velocities of {approx}10 km s{sup -1} and frequencies up to 200 kHz. Collisions with residual gas atoms slow down the rotating wave, whereas increasing ionization degree of the gas and plasmamore » conductivity speeds it up.« less

  4. Hamiltonian description of closed configurations of the vacuum magnetic field

    NASA Astrophysics Data System (ADS)

    Skovoroda, A. A.

    2015-05-01

    Methods of obtaining and using the Hamiltonians of closed vacuum magnetic configurations of fusion research systems are reviewed. Various approaches to calculate the flux functions determining the Hamiltonian are discussed. It is shown that the Hamiltonian description allows one not only to reproduce all traditional results, but also to study the behavior of magnetic field lines by using the theory of dynamic systems. The potentialities of the Hamiltonian formalism and its close relation to traditional methods are demonstrated using a large number of classical examples adopted from the fundamental works by A.I. Morozov, L.S. Solov'ev, and V.D. Shafranov.

  5. Investigation of Influence of Gas Ratio on the Electron Temperature in TiN Magnetron Sputtering Deposition System

    DTIC Science & Technology

    2013-07-01

    31st ICPIG, July 14-19, 2013, Granada , Spain Investigation of Influence of Gas Ratio on the Electron Temperature in TiN Magnetron Sputtering...ICPIG) Held in Granada , Spain on 14-19 July 2013 14. ABSTRACT In this work, a nanolayer of titanium nitride which produced by the magnetron

  6. A set of 14 DIP-SNP markers to detect unbalanced DNA mixtures.

    PubMed

    Liu, Zhizhen; Liu, Jinding; Wang, Jiaqi; Chen, Deqing; Liu, Zidong; Shi, Jie; Li, Zeqin; Li, Wenyan; Zhang, Gengqian; Du, Bing

    2018-03-04

    Unbalanced DNA mixture is still a difficult problem for forensic practice. DIP-STRs are useful markers for detection of minor DNA but they are not widespread in the human genome and having long amplicons. In this study, we proposed a novel type of genetic marker, termed DIP-SNP. DIP-SNP refers to the combination of INDEL and SNP in less than 300bp length of human genome. The multiplex PCR and SNaPshot assay were established for 14 DIP-SNP markers in a Chinese Han population from Shanxi, China. This novel compound marker allows detection of the minor DNA contributor with sensitivity from 1:50 to 1:1000 in a DNA mixture of any gender with 1 ng-10 ng DNA template. Most of the DIP-SNP markers had a relatively high probability of informative alleles with an average I value of 0.33. In all, we proposed DIP-SNP as a novel kind of genetic marker for detection of minor contributor from unbalanced DNA mixture and established the detection method by associating the multiplex PCR and SNaPshot assay. DIP-SNP polymorphisms are promising markers for forensic or clinical mixture examination because they are shorter, widespread and higher sensitive. Copyright © 2018 Elsevier Inc. All rights reserved.

  7. Experimental Investigation of Electron Cloud Containment in a Nonuniform Magnetic Field

    NASA Technical Reports Server (NTRS)

    Eninger, J. E.

    1974-01-01

    Dense clouds of electrons were generated and studied in an axisymmetric, nonuniform magnetic field created by a short solenoid. The operation of the experiment was similar to that of a low-pressure (approximately 0.000001 Torr) magnetron discharge. Discharge current characteristics are presented as a function of pressure, magnetic field strength, voltage, and cathode end-plate location. The rotation of the electron cloud is determined from the frequency of diocotron waves. In the space charge saturated regime of operation, the cloud is found to rotate as a solid body with frequency close to V sub a/phi sub a where V sub a is the anode voltage and phi suba is the total magnetic flux. This result indicates that, in regions where electrons are present, the magnetic field lines are electrostatic equipotentials (E bar, B bar = 0). Equilibrium electron density distributions suggested by this conditions are integrated with respect to total ionizing power and are found consistent with measured discharge currents.

  8. Existence of standard models of conic fibrations over non-algebraically-closed fields

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Avilov, A A

    2014-12-31

    We prove an analogue of Sarkisov's theorem on the existence of a standard model of a conic fibration over an algebraically closed field of characteristic different from two for three-dimensional conic fibrations over an arbitrary field of characteristic zero with an action of a finite group. Bibliography: 16 titles.

  9. Spectroscopic ellipsometry investigation of the optical properties of graphene oxide dip-coated on magnetron sputtered gold thin films

    NASA Astrophysics Data System (ADS)

    Politano, Grazia Giuseppina; Vena, Carlo; Desiderio, Giovanni; Versace, Carlo

    2018-02-01

    Despite intensive investigations on graphene oxide-gold nanocomposites, the interaction of graphene oxide sheets with magnetron sputtered gold thin films has not been studied yet. The optical constants of graphene oxide thin films dip-coated on magnetron sputtered gold thin films were determined by spectroscopic ellipsometry in the [300-1000] wavelength range. Moreover, the morphologic properties of the samples were investigated by SEM analysis. Graphene oxide absorbs mainly in the ultraviolet region, but when it is dip-coated on magnetron sputtered gold thin films, its optical constants show dramatic changes, becoming absorbing in the visible region, with a peak of the extinction coefficient at 3.1 eV. Using magnetron sputtered gold thin films as a substrate for graphene oxide thin films could therefore be the key to enhance graphene oxide optical sheets' properties for several technological applications, preserving their oxygen content and avoiding the reduction process.

  10. Mithras Studies of the Boundary Between Open and Closed Field Lines.

    DTIC Science & Technology

    1994-01-31

    I ¸ . . A- : - Final Report • March 1995 MITHRAS STUDIES OF THE BOUNDARY BETWEEN OPEN AND CLOSED FIELD LINES John D. Kelly, Program Manager Richard A...Kelly, Program Manager Richard A. Doe, Research Physicist Geoscience and Engineering Center SRI Project 3245 Prepared for: Department of the Air...characteristic energy, energy flux, and an estimate for upward field-aligned current. On the basis of coordinated radar/optical experiments, Vallance Jones et al

  11. Method to control deposition rate instabilities—High power impulse magnetron sputtering deposition of TiO{sub 2}

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kossoy, Anna, E-mail: annaeden@hi.is, E-mail: anna.kossoy@gmail.com; Magnusson, Rögnvaldur L.; Tryggvason, Tryggvi K.

    2015-03-15

    The authors describe how changes in shutter state (open/closed) affect sputter plasma conditions and stability of the deposition rate of Ti and TiO{sub 2} films. The films were grown by high power impulse magnetron sputtering in pure Ar and in Ar/O{sub 2} mixture from a metallic Ti target. The shutter state was found to have an effect on the pulse waveform for both pure Ar and reactive sputtering of Ti also affecting stability of TiO{sub 2} deposition rate. When the shutter opened, the shape of pulse current changed from rectangular to peak-plateau and pulse energy decreased. The authors attribute itmore » to the change in plasma impedance and gas rarefaction originating in geometry change in front of the magnetron. TiO{sub 2} deposition rate was initially found to be high, 1.45 Å/s, and then dropped by ∼40% during the first 5 min, while for Ti the change was less obvious. Instability of deposition rate poses significant challenge for growing multilayer heterostructures. In this work, the authors suggest a way to overcome this by monitoring the integrated average energy involved in the deposition process. It is possible to calibrate and control the film thickness by monitoring the integrated pulse energy and end growth when desired integrated pulse energy level has been reached.« less

  12. Magnetron-Sputtered Amorphous Metallic Coatings

    NASA Technical Reports Server (NTRS)

    Thakoor, A. P.; Mehra, M.; Khanna, S. K.

    1985-01-01

    Amorphous coatings of refractory metal/metalloid-based alloys deposited by magnetron sputtering provide extraordinary hardness and wear resistance. Sputtering target fabricated by thoroughly mixing powders of tungsten, rhenium, and boron in stated proportions and pressing at 1,200 degrees C and 3,000 lb/in. to second power (21 MPa). Substrate lightly etched by sputtering before deposition, then maintained at bias of - 500 V during initial stages of film growth while target material sputtered onto it. Argon gas at pressure used as carrier gas for sputter deposition. Coatings dense, pinhole-free, extremely smooth, and significantly resistant to chemical corrosion in acidic and neutral aqueous environments.

  13. Unbalanced Nature, Unbounded Bodies, and Unlimited Technology: Ecocriticism and Karen Traviss' Wess'har Series

    ERIC Educational Resources Information Center

    Sullivan, Heather I.

    2010-01-01

    While nature is often claimed to be a space of harmonized balance or an antidote to the chaos of the modern world, we need a more grounded assessment of nature as endlessly changing and much less predictable than we like to assume. In this essay, I explore Karen Traviss' provocative exploration of unbalanced nature and unbounded bodies in her…

  14. Phase control and fast start-up of a magnetron using modulation of an addressable faceted cathode

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Browning, J., E-mail: JimBrowning@BoiseState.edu; Fernandez-Gutierrez, S.; Lin, M. C.

    The use of an addressable, faceted cathode has been proposed as a method of modulating current injection in a magnetron to improve performance and control phase. To implement the controllable electron emission, five-sided and ten-sided faceted planar cathodes employing gated field emitters are considered as these emitters could be fabricated on flat substrates. For demonstration, the conformal finite-difference time-domain particle-in-cell simulation, as implemented in VORPAL, has been used to model a ten-cavity, rising sun magnetron using the modulated current sources and benchmarked against a typical continuous current source. For the modulated, ten-sided faceted cathode case, the electrons are injected frommore » three emitter elements on each of the ten facets. Each emitter is turned ON and OFF in sequence at the oscillating frequency with five emitters ON at one time to drive the five electron spokes of the π-mode. The emitter duty cycle is then 1/6th the Radio-Frequency (RF) period. Simulations show a fast start-up time as low as 35 ns for the modulated case compared to 100 ns for the continuous current cases. Analysis of the RF phase using the electron spoke locations and the RF magnetic field components shows that the phase is controlled for the modulated case while it is random, as typical, for the continuous current case. Active phase control during oscillation was demonstrated by shifting the phase of the electron injection 180° after oscillations started. The 180° phase shift time was approximately 25 RF cycles.« less

  15. A vector-free ECG interpretation with P, QRS & T waves as unbalanced transitions between stable configurations of the heart electric field during P-R, S-T & T-P segments

    PubMed Central

    2014-01-01

    Since cell membranes are weak sources of electrostatic fields, this ECG interpretation relies on the analogy between cells and electrets. It is here assumed that cell-bound electric fields unite, reach the body surface and the surrounding space and form the thoracic electric field that consists from two concentric structures: the thoracic wall and the heart. If ECG leads measure differences in electric potentials between skin electrodes, they give scalar values that define position of the electric field center along each lead. Repolarised heart muscle acts as a stable positive electric source, while depolarized heart muscle produces much weaker negative electric field. During T-P, P-R and S-T segments electric field is stable, only subtle changes are detectable by skin electrodes. Diastolic electric field forms after ventricular depolarization (T-P segments in the ECG recording). Telediastolic electric field forms after the atria have been depolarized (P-Q segments in the ECG recording). Systolic electric field forms after the ventricular depolarization (S-T segments in the ECG recording). The three ECG waves (P, QRS and T) can then be described as unbalanced transitions of the heart electric field from one stable configuration to the next and in that process the electric field center is temporarily displaced. In the initial phase of QRS, the rapidly diminishing septal electric field makes measured potentials dependent only on positive charges of the corresponding parts of the left and the right heart that lie within the lead axes. If more positive charges are near the "DOWN" electrode than near the "UP" electrode, a Q wave will be seen, otherwise an R wave is expected. Repolarization of the ventricular muscle is dampened by the early septal muscle repolarization that reduces deflection of T waves. Since the "UP" electrode of most leads is near the usually larger left ventricle muscle, T waves are in these leads positive, although of smaller amplitude and longer

  16. Unbalanced 5;16 translocation in a boy with papillary thyroid carcinoma

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    McDonald, M.; Maynard, S.; Sheldon, S.

    This is the first reported case of an unbalanced chromosome rearrangement resulting in trisomy 5q35.5{r_arrow}qter and monosomy 16p 13.3{r_arrow}pter, in a boy with mental and growth retardation, minor anomalies, and a history of bilateral papillary thyroid carcinoma. This was the result of a familial balanced translocation. The clinical and cytogenetic manifestations of the case are presented and the possible role of the chromosomal rearrangement in the etiology of the thyroid carcinoma is discussed. 25 refs., 5 figs., 1 tab.

  17. Quantum field theory in spaces with closed time-like curves

    NASA Astrophysics Data System (ADS)

    Boulware, D. G.

    Gott spacetime has closed timelike curves, but no locally anomalous stress-energy. A complete orthonormal set of eigenfunctions of the wave operator is found in the special case of a spacetime in which the total deficit angle is 27(pi). A scalar quantum field theory is constructed using these eigenfunctions. The resultant interacting quantum field theory is not unitary because the field operators can create real, on-shell, particles in the acausal region. These particles propagate for finite proper time accumulating an arbitrary phase before being annihilated at the same spacetime point as that at which they were created. As a result, the effective potential within the acausal region is complex, and probability is not conserved. The stress tensor of the scalar field is evaluated in the neighborhood of the Cauchy horizon; in the case of a sufficiently small Compton wavelength of the field, the stress tensor is regular and cannot prevent the formation of the Cauchy horizon.

  18. Closed and open magnetic fields in stellar winds

    NASA Technical Reports Server (NTRS)

    Mullan, D. J.; Steinolfson, R. S.

    1983-01-01

    A numerical study of the interaction between a thermal wind and a global dipole field in the sun and in a giant star is reported. In order for closed field lines to persist near the equator (where a helmet-streamer-like configuration appears), the coronal temperature must be less than a critical value Tc, which scales as M/R. This condition is found to be equivalent to the following: for a static helmet streamer to persist, the sonic point above the helmet must not approach closer to the star than 2.2-2.6 stellar radii. Implications for rapid mass loss and X-ray emission from cool giants are pointed out. The results strengthen the case for identifying empirical dividing lines in the H-R diagram with a magnetic topology transition locus (MTTL). Support for the MTTL concept is also provided by considerations of the breakdown of magnetostatic equilibrium.

  19. Drifting potential humps in ionization zones: The “propeller blades” of high power impulse magnetron sputtering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Anders, André; Ni, Pavel; Panjan, Matjaž

    2013-09-30

    Ion energy distribution functions measured for high power impulse magnetron sputtering show features, such as a broad peak at several 10 eV with an extended tail, as well as asymmetry with respect to E×B, where E and B are the local electric and magnetic field vectors, respectively. Here it is proposed that those features are due to the formation of a potential hump of several 10 V in each of the traveling ionization zones. Potential hump formation is associated with a negative-positive-negative space charge that naturally forms in ionization zones driven by energetic drifting electrons.

  20. Localized heating of electrons in ionization zones: Going beyond the Penning-Thornton paradigm in magnetron sputtering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Anders, Andre

    2014-12-07

    The fundamental question of how energy is supplied to a magnetron discharge is commonly answered by the Penning-Thornton paradigm invoking secondary electrons. Huo et al. (Plasma Sources Sci. Technol. 22, 045005, (2013)) used a global discharge model to show that electron heating in the electric field of the magnetic presheath is dominant. In this contribution, this concept is applied locally taking into account the electric potential structure of ionization zones. Images of ionization zones can and should be interpreted as diagrams of the localization of electric potential and related electron energy, where certain collisions promote or dampen their formation.

  1. Recent operation of the FNAL magnetron H- ion source

    NASA Astrophysics Data System (ADS)

    Karns, P. R.; Bollinger, D. S.; Sosa, A.

    2017-08-01

    This paper will detail changes in the operational paradigm of the Fermi National Accelerator Laboratory (FNAL) magnetron H- ion source due to upgrades in the accelerator system. Prior to November of 2012 the H- ions for High Energy Physics (HEP) experiments were extracted at ˜18 keV vertically downward into a 90 degree bending magnet and accelerated through a Cockcroft-Walton accelerating column to 750 keV. Following the upgrade in the fall of 2012 the H- ions are now directly extracted from a magnetron at 35 keV and accelerated to 750 keV by a Radio Frequency Quadrupole (RFQ). This change in extraction energy as well as the orientation of the ion source required not only a redesign of the ion source, but an updated understanding of its operation at these new values. Discussed in detail are the changes to the ion source timing, arc discharge current, hydrogen gas pressure, and cesium delivery system that were needed to maintain consistent operation at >99% uptime for HEP, with an increased ion source lifetime of over 9 months.

  2. An improved synchronous reference frame current control strategy for a photovoltaic grid-connected inverter under unbalanced and nonlinear load conditions.

    PubMed

    Naderipour, Amirreza; Asuhaimi Mohd Zin, Abdullah; Bin Habibuddin, Mohd Hafiz; Miveh, Mohammad Reza; Guerrero, Josep M

    2017-01-01

    In recent years, renewable energy sources have been considered the most encouraging resources for grid and off-grid power generation. This paper presents an improved current control strategy for a three-phase photovoltaic grid-connected inverter (GCI) under unbalanced and nonlinear load conditions. It is challenging to suppress the harmonic content in the output current below a pre-set value in the GCI. It is also difficult to compensate for unbalanced loads even when the grid is under disruption due to total harmonic distortion (THD) and unbalanced loads. The primary advantage and objective of this method is to effectively compensate for the harmonic current content of the grid current and microgrid without the use of any compensation devices, such as active and passive filters. This method leads to a very low THD in both the GCI currents and the current exchanged with the grid. The control approach is designed to control the active and reactive power and harmonic current compensation, and it also corrects the system unbalance. The proposed control method features the synchronous reference frame (SRF) method. Simulation results are presented to demonstrate the effective performance of the proposed method.

  3. An improved synchronous reference frame current control strategy for a photovoltaic grid-connected inverter under unbalanced and nonlinear load conditions

    PubMed Central

    Naderipour, Amirreza; Asuhaimi Mohd Zin, Abdullah; Bin Habibuddin, Mohd Hafiz; Miveh, Mohammad Reza; Guerrero, Josep M.

    2017-01-01

    In recent years, renewable energy sources have been considered the most encouraging resources for grid and off-grid power generation. This paper presents an improved current control strategy for a three-phase photovoltaic grid-connected inverter (GCI) under unbalanced and nonlinear load conditions. It is challenging to suppress the harmonic content in the output current below a pre-set value in the GCI. It is also difficult to compensate for unbalanced loads even when the grid is under disruption due to total harmonic distortion (THD) and unbalanced loads. The primary advantage and objective of this method is to effectively compensate for the harmonic current content of the grid current and microgrid without the use of any compensation devices, such as active and passive filters. This method leads to a very low THD in both the GCI currents and the current exchanged with the grid. The control approach is designed to control the active and reactive power and harmonic current compensation, and it also corrects the system unbalance. The proposed control method features the synchronous reference frame (SRF) method. Simulation results are presented to demonstrate the effective performance of the proposed method. PMID:28192436

  4. Fabrication and characterization of flaky core-shell particles by magnetron sputtering silver onto diatomite

    NASA Astrophysics Data System (ADS)

    Wang, Yuanyuan; Zhang, Deyuan; Cai, Jun

    2016-02-01

    Diatomite has delicate porous structures and various shapes, making them ideal templates for microscopic core-shell particles fabrication. In this study, a new process of magnetron sputtering assisted with photoresist positioning was proposed to fabricate lightweight silver coated porous diatomite with superior coating quality and performance. The diatomite has been treated with different sputtering time to investigate the silver film growing process on the surface. The morphologies, constituents, phase structures and surface roughness of the silver coated diatomite were analyzed with SEM, EDS, XRD and AFM respectively. The results showed that the optimized magnetron sputtering time was 8-16 min, under which the diatomite templates were successfully coated with uniform silver film, which exhibits face centered cubic (fcc) structure, and the initial porous structures were kept. Moreover, this silver coating has lower surface roughness (RMS 4.513 ± 0.2 nm) than that obtained by electroless plating (RMS 15.692 ± 0.5 nm). And the infrared emissivity of coatings made with magnetron sputtering and electroless plating silver coated diatomite can reach to the lowest value of 0.528 and 0.716 respectively.

  5. Autovibration and chaotic motion of an unbalanced rotor in massive non-linear compliant supports

    NASA Astrophysics Data System (ADS)

    Pasynkova, I. A.; Stepanova, P. P.

    2018-05-01

    Stability loss scenarios of an unbalanced rotor with a flexible massless shaft mounted in massive non-linear compliant supports are studied on the example of cylindrical precession. Dyffing type of non-linearity in compliant supports is considered. The system "rotor - supports" has eight degrees of freedom. Internal and external friction are taken into account. Autovibrations and chaotic vibrations are obtained. The results are confirmed by numerical check.

  6. Ensemble Pruning for Glaucoma Detection in an Unbalanced Data Set.

    PubMed

    Adler, Werner; Gefeller, Olaf; Gul, Asma; Horn, Folkert K; Khan, Zardad; Lausen, Berthold

    2016-12-07

    Random forests are successful classifier ensemble methods consisting of typically 100 to 1000 classification trees. Ensemble pruning techniques reduce the computational cost, especially the memory demand, of random forests by reducing the number of trees without relevant loss of performance or even with increased performance of the sub-ensemble. The application to the problem of an early detection of glaucoma, a severe eye disease with low prevalence, based on topographical measurements of the eye background faces specific challenges. We examine the performance of ensemble pruning strategies for glaucoma detection in an unbalanced data situation. The data set consists of 102 topographical features of the eye background of 254 healthy controls and 55 glaucoma patients. We compare the area under the receiver operating characteristic curve (AUC), and the Brier score on the total data set, in the majority class, and in the minority class of pruned random forest ensembles obtained with strategies based on the prediction accuracy of greedily grown sub-ensembles, the uncertainty weighted accuracy, and the similarity between single trees. To validate the findings and to examine the influence of the prevalence of glaucoma in the data set, we additionally perform a simulation study with lower prevalences of glaucoma. In glaucoma classification all three pruning strategies lead to improved AUC and smaller Brier scores on the total data set with sub-ensembles as small as 30 to 80 trees compared to the classification results obtained with the full ensemble consisting of 1000 trees. In the simulation study, we were able to show that the prevalence of glaucoma is a critical factor and lower prevalence decreases the performance of our pruning strategies. The memory demand for glaucoma classification in an unbalanced data situation based on random forests could effectively be reduced by the application of pruning strategies without loss of performance in a population with increased

  7. Lyapounov Functions of Closed Cone Fields: From Conley Theory to Time Functions

    NASA Astrophysics Data System (ADS)

    Bernard, Patrick; Suhr, Stefan

    2018-03-01

    We propose a theory "à la Conley" for cone fields using a notion of relaxed orbits based on cone enlargements, in the spirit of space time geometry. We work in the setting of closed (or equivalently semi-continuous) cone fields with singularities. This setting contains (for questions which are parametrization independent such as the existence of Lyapounov functions) the case of continuous vector-fields on manifolds, of differential inclusions, of Lorentzian metrics, and of continuous cone fields. We generalize to this setting the equivalence between stable causality and the existence of temporal functions. We also generalize the equivalence between global hyperbolicity and the existence of a steep temporal function.

  8. TU-H-BRA-02: The Physics of Magnetic Field Isolation in a Novel Compact Linear Accelerator Based MRI-Guided Radiation Therapy System

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Low, D; Mutic, S; Shvartsman, S

    Purpose: To develop a method for isolating the MRI magnetic field from field-sensitive linear accelerator components at distances close to isocenter. Methods: A MRI-guided radiation therapy system has been designed that integrates a linear accelerator with simultaneous MR imaging. In order to accomplish this, the magnetron, port circulator, radiofrequency waveguide, gun driver, and linear accelerator needed to be placed in locations with low magnetic fields. The system was also required to be compact, so moving these components far from the main magnetic field and isocenter was not an option. The magnetic field sensitive components (exclusive of the waveguide) were placedmore » in coaxial steel sleeves that were electrically and mechanically isolated and whose thickness and placement were optimized using E&M modeling software. Six sets of sleeves were placed 60° apart, 85 cm from isocenter. The Faraday effect occurs when the direction of propagation is parallel to the magnetic RF field component, rotating the RF polarization, subsequently diminishing RF power. The Faraday effect was avoided by orienting the waveguides such that the magnetic field RF component was parallel to the magnetic field. Results: The magnetic field within the shields was measured to be less than 40 Gauss, significantly below the amount needed for the magnetron and port circulator. Additional mu-metal was employed to reduce the magnetic field at the linear accelerator to less than 1 Gauss. The orientation of the RF waveguides allowed the RT transport with minimal loss and reflection. Conclusion: One of the major challenges in designing a compact linear accelerator based MRI-guided radiation therapy system, that of creating low magnetic field environments for the magnetic-field sensitive components, has been solved. The measured magnetic fields are sufficiently small to enable system integration. This work supported by ViewRay, Inc.« less

  9. Efficacy and safety of one-stage posterior hemivertebral resection for unbalanced multiple hemivertebrae: A more than 2-year follow-up.

    PubMed

    Huang, Yong; Feng, Ganjun; Song, Yueming; Liu, Limin; Zhou, Chunguang; Wang, Lei; Zhou, Zhongjie; Yang, Xi

    2017-09-01

    One-stage posterior hemivertebral resection has been proven to be an effective, reliable surgical option for treating congenital scoliosis due to a single hemivertebra. To date, however, no studies of treating unbalanced multiple hemivertebrae have appeared. This study evaluated the efficacy and safety of one-stage posterior hemivertebral resection for unbalanced multiple hemivertebrae. Altogether, we studied 15 patients with unbalanced multiple hemivertebrae who had undergone hemivertebral resection using the one-stage posterior approach with at least 2 years of follow-up. Clinical outcomes were assessed radiographically and with the Scoliosis Research Society-22 (SRS-22) score. Related complications were also recorded. The mean Cobb angle of the main curve was 62.4° (46°-98°) before surgery and 18.2° (9°-33°) at the most recent follow-up (average correction 73.3%). The compensatory cranial curve was corrected from 28.5° (11°-52°) to 9.1° (0°-30°) (average correction 70.0%). The compensatory caudal curve was corrected from 31.6° (14°-54°) to 6.9°(0°-19°) (average correction 79.1%). The segmental kyphosis/lordosis was corrected from 41.1° (-40° to 98°) to 12.3° (-25° to 41°) (average correction 65.5%). The mean growth rate of the T1-S1 length in immature patients was 9.8mm/year during the follow-up period. Health-related quality of life (SRS-22 score) had significantly improved. Complications include one wound infection and one developing deformity. One-stage posterior hemivertebral resection for unbalanced multiple hemivertebrae provides good radiographic and clinical outcomes with no severe complications when performed by an experienced surgeon. Longer follow-up to detect late complications is obligatory. Copyright © 2017 Elsevier B.V. All rights reserved.

  10. Large unbalanced credit scoring using Lasso-logistic regression ensemble.

    PubMed

    Wang, Hong; Xu, Qingsong; Zhou, Lifeng

    2015-01-01

    Recently, various ensemble learning methods with different base classifiers have been proposed for credit scoring problems. However, for various reasons, there has been little research using logistic regression as the base classifier. In this paper, given large unbalanced data, we consider the plausibility of ensemble learning using regularized logistic regression as the base classifier to deal with credit scoring problems. In this research, the data is first balanced and diversified by clustering and bagging algorithms. Then we apply a Lasso-logistic regression learning ensemble to evaluate the credit risks. We show that the proposed algorithm outperforms popular credit scoring models such as decision tree, Lasso-logistic regression and random forests in terms of AUC and F-measure. We also provide two importance measures for the proposed model to identify important variables in the data.

  11. Excess velocity of magnetic domain walls close to the depinning field

    NASA Astrophysics Data System (ADS)

    Caballero, Nirvana B.; Fernández Aguirre, Iván; Albornoz, Lucas J.; Kolton, Alejandro B.; Rojas-Sánchez, Juan Carlos; Collin, Sophie; George, Jean Marie; Diaz Pardo, Rebeca; Jeudy, Vincent; Bustingorry, Sebastian; Curiale, Javier

    2017-12-01

    Magnetic field driven domain wall velocities in [Co/Ni] based multilayers thin films have been measured using polar magneto-optic Kerr effect microscopy. The low field results are shown to be consistent with the universal creep regime of domain wall motion, characterized by a stretched exponential growth of the velocity with the inverse of the applied field. Approaching the depinning field from below results in an unexpected excess velocity with respect to the creep law. We analyze these results using scaling theory to show that this speeding up of domain wall motion can be interpreted as due to the increase of the size of the deterministic relaxation close to the depinning transition. We propose a phenomenological model to accurately fit the observed excess velocity and to obtain characteristic values for the depinning field Hd, the depinning temperature Td, and the characteristic velocity scale v0 for each sample.

  12. Exactly solvable field theories of closed strings

    NASA Astrophysics Data System (ADS)

    Brézin, E.; Kazakov, V. A.

    1990-02-01

    Field theories of closed strings are shown to be exactly solvable for a central charge of matter fields c=1-6/m(m+1),m=1,2, 3, .... The two-point function χ(λ,N), in which λ is the cosmological constant and N-1 is the string coupling constant, obeys a scaling law χ(λ,N=N-(m+1/2)C((λc-λ)Nm/(m+1/2)) in the limit in which N-1 goes to zero and λ goes to a critical value λc we have determined the universal non-linear differential equation satisfied by the function C. From this equation it is found that a phase transition takes place for some finite value of the scaling parameter (λc-λ)Nm/(m+1/2); this transition is a ``condensation of handles'' on the world sheet, characterized by a divergence of the averaged genus of the world sheets. The cases m=2,3 are elaborated in more details, and the case m=1, which corresponds to the embedding of a bosonic string in -2 dimensions, is reduced to explicit quadratures. Permanent address: Cybernetics Council and Academy of Sciences, ul. Vavilova 40, SU-117 333 Moscow, USSR.

  13. A hybrid electron cyclotron resonance metal ion source with integrated sputter magnetron for the production of an intense Al{sup +} ion beam

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Weichsel, T., E-mail: tim.weichsel@fep.fraunhofer.de; Hartung, U.; Kopte, T.

    2015-09-15

    A metal ion source prototype has been developed: a combination of magnetron sputter technology with 2.45 GHz electron cyclotron resonance (ECR) ion source technology—a so called magnetron ECR ion source (MECRIS). An integrated ring-shaped sputter magnetron with an Al target is acting as a powerful metal atom supply in order to produce an intense current of singly charged metal ions. Preliminary experiments show that an Al{sup +} ion current with a density of 167 μA/cm{sup 2} is extracted from the source at an acceleration voltage of 27 kV. Spatially resolved double Langmuir probe measurements and optical emission spectroscopy were usedmore » to study the plasma states of the ion source: sputter magnetron, ECR, and MECRIS plasma. Electron density and temperature as well as Al atom density were determined as a function of microwave and sputter magnetron power. The effect of ECR heating is strongly pronounced in the center of the source. There the electron density is increased by one order of magnitude from 6 × 10{sup 9} cm{sup −3} to 6 × 10{sup 10} cm{sup −3} and the electron temperature is enhanced from about 5 eV to 12 eV, when the ECR plasma is ignited to the magnetron plasma. Operating the magnetron at constant power, it was observed that its discharge current is raised from 1.8 A to 4.8 A, when the ECR discharge was superimposed with a microwave power of 2 kW. At the same time, the discharge voltage decreased from about 560 V to 210 V, clearly indicating a higher plasma density of the MECRIS mode. The optical emission spectrum of the MECRIS plasma is dominated by lines of excited Al atoms and shows a significant contribution of lines arising from singly ionized Al. Plasma emission photography with a CCD camera was used to prove probe measurements and to identify separated plasma emission zones originating from the ECR and magnetron discharge.« less

  14. Performance of unbalanced QPSK in the presence of noisy reference and crosstalk

    NASA Technical Reports Server (NTRS)

    Divsalar, D.; Yuen, J. H.

    1979-01-01

    The problem of transmitting two telemetry data streams having different rates and different powers using unbalanced quadriphase shift keying (UQPSK) signaling is considered. It is noted that the presence of a noisy carrier phase reference causes a degradation in detection performance in coherent communications systems and that imperfect carrier synchronization not only attenuates the main demodulated signal voltage in UQPSK but also produces interchannel interference (crosstalk) which degrades the performance still further. Exact analytical expressions for symbol error probability of UQPSK in the presence of noise phase reference are derived.

  15. Elementary surface processes during reactive magnetron sputtering of chromium

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Monje, Sascha; Corbella, Carles, E-mail: carles.corbella@rub.de; Keudell, Achim von

    2015-10-07

    The elementary surface processes occurring on chromium targets exposed to reactive plasmas have been mimicked in beam experiments by using quantified fluxes of Ar ions (400–800 eV) and oxygen atoms and molecules. For this, quartz crystal microbalances were previously coated with Cr thin films by means of high-power pulsed magnetron sputtering. The measured growth and etching rates were fitted by flux balance equations, which provided sputter yields of around 0.05 for the compound phase and a sticking coefficient of O{sub 2} of 0.38 on the bare Cr surface. Further fitted parameters were the oxygen implantation efficiency and the density of oxidationmore » sites at the surface. The increase in site density with a factor 4 at early phases of reactive sputtering is identified as a relevant mechanism of Cr oxidation. This ion-enhanced oxygen uptake can be attributed to Cr surface roughening and knock-on implantation of oxygen atoms deeper into the target. This work, besides providing fundamental data to control oxidation state of Cr targets, shows that the extended Berg's model constitutes a robust set of rate equations suitable to describe reactive magnetron sputtering of metals.« less

  16. Structure of the metallic films deposited on small spheres trapped in the rf magnetron plasma

    NASA Astrophysics Data System (ADS)

    Filippov, A. V.; Pal, A. F.; Ryabinkin, A. N.; Serov, A. O.

    2016-11-01

    Metallic coatings were deposited onto glass spheres having diameters from several to one hundred micrometers by the magnetron sputtering. Two different experimental schemes were exploited. One of them had the traditional configuration where a magnetron sputter was placed at one hundred millimeters from particles. In this scheme, continuous mechanical agitation in a fluidized bed was used to achieve uniformity of coatings. In the second scheme the treated particles (substrates) levitated in a magnetron rf plasma over a sputtered rf electrode (target) at the distance d of few mm from it and at gas pressure p values of 30-100 mTorr. These parameters are essentially different from those in the traditional sputtering. Agitation due to the features of a particle confinement in dusty plasma was used here to obtain uniform coatings. Thickness and morphology of the obtained coatings were studied. As it is known, film growth rate and structure are determined by the substrate temperature, the densities of ion and neutral atom fluxes to the substrate surface, the radiation flux density, and the heat energy produced due to the surface condensation of atoms and recombination of electrons and ions. These parameters particularly depend on the product of p and d. In the case of magnetron rf dusty plasma, it is possible to achieve the pd value several times lower than the lowest value proper to the first traditional case. Completely different dependencies of the film growth rate and structure on the pd value in these sputtering processes were observed and qualitatively explained.

  17. Rarefaction windows in a high-power impulse magnetron sputtering plasma

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Palmucci, Maria; Britun, Nikolay; Konstantinidis, Stephanos

    2013-09-21

    The velocity distribution function of the sputtered particles in the direction parallel to the planar magnetron cathode is studied by spatially- and time-resolved laser-induced fluorescence spectroscopy in a short-duration (20 μs) high-power impulse magnetron sputtering discharge. The experimental evidence for the neutral and ionized sputtered particles to have a constant (saturated) velocity at the end of the plasma on-time is demonstrated. The velocity component parallel to the target surface reaches the values of about 5 km/s for Ti atoms and ions, which is higher that the values typically measured in the direct current sputtering discharges before. The results point outmore » on the presence of a strong gas rarefaction significantly reducing the sputtered particles energy dissipation during a certain time interval at the end of the plasma pulse, referred to as “rarefaction window” in this work. The obtained results agree with and essentially clarify the dynamics of HiPIMS discharge studied during the plasma off-time previously in the work: N. Britun, Appl. Phys. Lett. 99, 131504 (2011)« less

  18. Closed-form nonlinear frequency of flexoelectric nanobeams with surface and nonlocal effects under closed circuit electric field

    NASA Astrophysics Data System (ADS)

    Barati, Mohammad Reza

    2018-02-01

    Nonlocal and surface effects on nonlinear vibration characteristics of a flexoelectric nanobeams under magnetic field are examined. Eringen’s nonlocal elasticity as well as surface elasticity theories are employed to describe the size-dependency of the flexoelectric nanobeam. Also, flexoelectricity is an important size-dependent phenomena for piezoelectric structures at nanoscale, related to the strain gradient-electric polarization coupling. After the derivation of governing equation via Hamilton’s principle, Galerkin method is employed to satisfy boundary conditions. Also, analytical procedures are implemented to obtain the closed-form nonlinear frequency of flexoelectric nanobeam. It is showed that magnetic field intensity, flexoelectric parameter, nonlocal parameter, elastic foundation and applied voltage on the top surface of the nanobeam have great influences on nonlinear vibration frequency.

  19. Performance Evaluation of UPQC under Nonlinear Unbalanced Load Conditions Using Synchronous Reference Frame Based Control

    NASA Astrophysics Data System (ADS)

    Kota, Venkata Reddy; Vinnakoti, Sudheer

    2017-12-01

    Today, maintaining Power Quality (PQ) is very important in the growing competent world. With new equipments and devices, new challenges are also being put before power system operators. Unified Power Quality Conditioner (UPQC) is proposed to mitigate many power quality problems and to improve the performance of the power system. In this paper, an UPQC with Fuzzy Logic controller for capacitor voltage balancing is proposed in Synchronous Reference Frame (SRF) based control with Modified Phased Locked Loop (MPLL). The proposed controller with SRF-MPLL based control is tested under non-linear and unbalanced load conditions. The system is developed in Matlab/Simulink and its performance is analyzed under various conditions like non-linear, unbalanced load and polluted supply voltage including voltage sag/swells. Active and reactive power flow in the system, power factor and %THD of voltages and currents before and after compensation are also analyzed in this work. Results prove the applicability of the proposed scheme for power quality improvement. It is observed that the fuzzy controller gives better performance than PI controller with faster capacitor voltage balancing and also improves the dynamic performance of the system.

  20. Large Unbalanced Credit Scoring Using Lasso-Logistic Regression Ensemble

    PubMed Central

    Wang, Hong; Xu, Qingsong; Zhou, Lifeng

    2015-01-01

    Recently, various ensemble learning methods with different base classifiers have been proposed for credit scoring problems. However, for various reasons, there has been little research using logistic regression as the base classifier. In this paper, given large unbalanced data, we consider the plausibility of ensemble learning using regularized logistic regression as the base classifier to deal with credit scoring problems. In this research, the data is first balanced and diversified by clustering and bagging algorithms. Then we apply a Lasso-logistic regression learning ensemble to evaluate the credit risks. We show that the proposed algorithm outperforms popular credit scoring models such as decision tree, Lasso-logistic regression and random forests in terms of AUC and F-measure. We also provide two importance measures for the proposed model to identify important variables in the data. PMID:25706988

  1. Advanced, phase-locked, 100 kW, 1.3 GHz magnetron

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Read, Michael; Ives, R. Lawrence; Bui, Thuc

    Calabazas Creek Research, Inc., in collaboration with Fermilab and Communications & Power Industries, LLC, is developing a phase-locked, 100 kW peak, 10 kW average power magnetron-based RF system for driving accelerators. Here, phase locking will be achieved using an approach originating at Fermilab that includes control of both amplitude and phase on a fast time scale.

  2. Advanced, phase-locked, 100 kW, 1.3 GHz magnetron

    DOE PAGES

    Read, Michael; Ives, R. Lawrence; Bui, Thuc; ...

    2017-03-06

    Calabazas Creek Research, Inc., in collaboration with Fermilab and Communications & Power Industries, LLC, is developing a phase-locked, 100 kW peak, 10 kW average power magnetron-based RF system for driving accelerators. Here, phase locking will be achieved using an approach originating at Fermilab that includes control of both amplitude and phase on a fast time scale.

  3. Express penetration of hydrogen on Mg(10͞13) along the close-packed-planes.

    PubMed

    Ouyang, Liuzhang; Tang, Jiajun; Zhao, Yujun; Wang, Hui; Yao, Xiangdong; Liu, Jiangwen; Zou, Jin; Zhu, Min

    2015-06-01

    Metal atoms often locate in energetically favorite close-packed planes, leading to a relatively high penetration barrier for other atoms. Naturally, the penetration would be much easier through non-close-packed planes, i.e. high-index planes. Hydrogen penetration from surface to the bulk (or reversely) across the packed planes is the key step for hydrogen diffusion, thus influences significantly hydrogen sorption behaviors. In this paper, we report a successful synthesis of Mg films in preferential orientations with both close- and non-close-packed planes, i.e. (0001) and a mix of (0001) and (10͞13), by controlling the magnetron sputtering conditions. Experimental investigations confirmed a remarkable decrease in the hydrogen absorption temperature in the Mg (10͞13), down to 392 K from 592 K of the Mg film (0001), determined by the pressure-composition-isothermal (PCI) measurement. The ab initio calculations reveal that non-close-packed Mg(10͞13) slab is advantageous for hydrogen sorption, attributing to the tilted close-packed-planes in the Mg(10͞13) slab.

  4. Effects of Duplex Nitriding and TiN Coating Treatment on Wear Resistance, Corrosion Resistance and Biocompatibility of Ti6Al4V Alloy

    NASA Astrophysics Data System (ADS)

    Kao, W. H.; Su, Y. L.; Hsieh, Y. T.

    2017-08-01

    Ti6Al4V alloy substrates were nitrided at 900 °C. TiN coatings were then deposited on the nitrided substrates using a closed-field unbalanced magnetron sputtering system. The microstructure, hardness and adhesion properties of the TiN-N-Ti6Al4V substrates were evaluated and compared with those of an untreated Ti6Al4V sample, a nitrided Ti6Al4V sample and a TiN-coated Ti6Al4V sample, respectively. The tribological properties of the various samples were investigated by means of reciprocating sliding wear tests performed in 0.9 wt.% NaCl solution against 316L, Si3N4 and Ti6Al4V balls, respectively. In addition, the corrosion resistance was evaluated using potentiodynamic polarization tests. Finally, the biocompatibility of the samples was investigated by observing the attachment and growth of purified mouse leukemic monocyte/macrophage cells (Raw 264.7) on the sample surface after culturing periods of 24, 72 and 120 h, respectively. Overall, the results showed that the duplex nitriding/TiN coating treatment significantly improved the tribological, anti-corrosion and biocompatibility properties of the original Ti6Al4V alloy.

  5. [Effects of magnetron sputtered ZrN on the bonding strength of titanium porcelain].

    PubMed

    Zhou, Shu; Zhang, Wen-yan; Guang, Han-bing; Xia, Yang; Zhang, Fei-min

    2009-04-01

    To investigate the effect of magnetron sputtered ZrN on the bonding strength between a low-fusing porcelain (Ti/Vita titankeramik system) and commercially pure cast titanium. Sixteen specimens were randomly assigned to test group and control group (n=8). The control group received no surface treated. Magnetron sputtered ZrN film was deposited on the surface of specimens in the test group. Then the sixteen titanium-porcelain specimens were prepared in a rectangular shape and went through three-point bending test on a universal test machine. The bond strength of Ti/porcelain was recorded. The phase composition of the specimens was analyzed using X-ray diffraction (XRD). The interface at titanium and porcelain and the titanium surface after debonding were observed with a scanning electron microscopy (SEM) and analyzed using energy depressive spectrum (EDS). New phase of ZrN was found with XRD in the test group. Statistical analysis showed higher bond strength following ZrN surface treatment in the test group [(45.991+/-0.648) MPa] than that in the control group [(29.483+/-1.007) MPa] (P=0.000). Bonded ceramic could be observed in test group, the amount of bonded ceramic was more than that in the control group. No obvious bonded ceramic in control group was found. Magnetron sputtered ZrN can improve bond strength of Ti/Vita titankeramik system significantly.

  6. Investigating cellular network heterogeneity and modularity in cancer: a network entropy and unbalanced motif approach.

    PubMed

    Cheng, Feixiong; Liu, Chuang; Shen, Bairong; Zhao, Zhongming

    2016-08-26

    Cancer is increasingly recognized as a cellular system phenomenon that is attributed to the accumulation of genetic or epigenetic alterations leading to the perturbation of the molecular network architecture. Elucidation of network properties that can characterize tumor initiation and progression, or pinpoint the molecular targets related to the drug sensitivity or resistance, is therefore of critical importance for providing systems-level insights into tumorigenesis and clinical outcome in the molecularly targeted cancer therapy. In this study, we developed a network-based framework to quantitatively examine cellular network heterogeneity and modularity in cancer. Specifically, we constructed gene co-expressed protein interaction networks derived from large-scale RNA-Seq data across 8 cancer types generated in The Cancer Genome Atlas (TCGA) project. We performed gene network entropy and balanced versus unbalanced motif analysis to investigate cellular network heterogeneity and modularity in tumor versus normal tissues, different stages of progression, and drug resistant versus sensitive cancer cell lines. We found that tumorigenesis could be characterized by a significant increase of gene network entropy in all of the 8 cancer types. The ratio of the balanced motifs in normal tissues is higher than that of tumors, while the ratio of unbalanced motifs in tumors is higher than that of normal tissues in all of the 8 cancer types. Furthermore, we showed that network entropy could be used to characterize tumor progression and anticancer drug responses. For example, we found that kinase inhibitor resistant cancer cell lines had higher entropy compared to that of sensitive cell lines using the integrative analysis of microarray gene expression and drug pharmacological data collected from the Genomics of Drug Sensitivity in Cancer database. In addition, we provided potential network-level evidence that smoking might increase cancer cellular network heterogeneity and

  7. High-latitude convection on open and closed field lines for large IMF B(y)

    NASA Technical Reports Server (NTRS)

    Moses, J. J.; Crooker, N. U.; Gorney, D. J.; Siscoe, G. L.

    1985-01-01

    S3-3 electric field observations for August 23, 1976, show a single convection cell engulfing the northern polar cap. The flow direction is that for a positive IMF B(y) component. The particle data indicate that nearly half the duskside sunward flow occurs on closed field lines whereas the dawnside flow is entirely on open field lines. This is interpreted in terms of an IMF B(y)-induced deformation in the polar cap boundary, where the deformation moves with the convective flow. Thus, convection streamlines cross the deformed polar cap boundary, but no flow crosses the boundary because it is carried by the flow. Since southern hemisphere convection is expected to occur with the opposite sense of rotation, closed field lines that will be forced to tilt azimuthally are predicted. On the nightside the tilt produces a y component of the magnetic field in the same direction as the IMF for either sign of IMF B(y). This interpretation is consistent with observations of a greater y component in the plasma sheet than the tail lobes, which are difficult to understand in terms of the common explanation of IMF penetration. Alternatives to this interpretation are also discussed.

  8. Controllable transition from positive space charge to negative space charge in an inverted cylindrical magnetron

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Rane, R., E-mail: ramu@ipr.res.in; Ranjan, M.; Mukherjee, S.

    2016-01-15

    The combined effect of magnetic field (B), gas pressure (P), and the corresponding discharge voltage on the discharge properties of argon in inverted cylindrical magnetron has been investigated. In the experiment, anode is biased with continuous 10 ms sinusoidal half wave. It is observed that at a comparatively higher magnetic field (i.e., >200 gauss) and lower operating pressure (i.e., <1 × 10{sup −3} mbar), the discharge extinguishes and demands a high voltage to reignite. Discharge current increases with increase in magnetic field and starts reducing at sufficiently higher magnetic field for a particular discharge voltage due to restricted electron diffusion towards the anode.more » It is observed that B/P ratio plays an important role in sustaining the discharge and is constant for a discharge voltage. The discharge is transformed to negative space charge regime from positive space charge regime at certain B/P ratio and this ratio varies linearly with the discharge voltage. The space charge reversal is indicated by the radial profile of the floating potential and plasma potential in between two electrodes for different magnetic fields. At a particular higher magnetic field (beyond 100 gauss), the floating potential increases gradually with the radial distance from cathode, whereas it remains almost constant at lower magnetic field.« less

  9. Oleophobic optical coating deposited by magnetron PVD

    NASA Astrophysics Data System (ADS)

    Bernt, D.; Ponomarenko, V.; Pisarev, A.

    2016-09-01

    Thin oxinitride films of Zn-Sn-O-N and Si-Al-O-N were deposited on glass by reactive magnetron sputtering at various nitrogen-to-oxygen ratios. Nitrogen added to oxygen led to decrease of the surface roughness and increase of oleophobic properties studied by the oil-drop test. The best oleophobity was obtained for Zn-Sn-O-N oxinitride at Zn:Sn=1:1 and N:O=1:2. Improved oleophobic properties were also demonstrated if the oxinitride film was deposited on top of the multilayer coating as the final step in the industrial cycle of production of energy efficient glass.

  10. Sputter deposition of MgxAlyOz thin films in a dual-magnetron device: a multi-species Monte Carlo model

    NASA Astrophysics Data System (ADS)

    Yusupov, M.; Saraiva, M.; Depla, D.; Bogaerts, A.

    2012-07-01

    A multi-species Monte Carlo (MC) model, combined with an analytical surface model, has been developed in order to investigate the general plasma processes occurring during the sputter deposition of complex oxide films in a dual-magnetron sputter deposition system. The important plasma species, such as electrons, Ar+ ions, fast Ar atoms and sputtered metal atoms (i.e. Mg and Al atoms) are described with the so-called multi-species MC model, whereas the deposition of MgxAlyOz films is treated by an analytical surface model. Target-substrate distances for both magnetrons in the dual-magnetron setup are varied for the purpose of growing stoichiometric complex oxide thin films. The metal atoms are sputtered from pure metallic targets, whereas the oxygen flux is only directed toward the substrate and is high enough to obtain fully oxidized thin films but low enough to avoid target poisoning. The calculations correspond to typical experimental conditions applied to grow these complex oxide films. In this paper, some calculation results are shown, such as the densities of various plasma species, their fluxes toward the targets and substrate, the deposition rates, as well as the film stoichiometry. Moreover, some results of the combined model are compared with experimental observations. Note that this is the first complete model, which can be applied for large and complicated magnetron reactor geometries, such as dual-magnetron configurations. With this model, we are able to describe all important plasma species as well as the deposition process. It can also be used to predict film stoichiometries of complex oxide films on the substrate.

  11. Electrical characteristics of thin Ta2O5 films deposited by reactive pulsed direct-current magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Kim, J.-Y.; Nielsen, M. C.; Rymaszewski, E. J.; Lu, T.-M.

    2000-02-01

    Room temperature deposition of tantalum oxide films on metallized silicon substrates was investigated by reactive pulsed magnetron sputtering of Ta in an Ar/O2 ambient. The dielectric constant of the tantalum oxide ranged from 19 to 31 depending on the oxygen percentage [P(%)=PO2/(PO2+PAr)] used during sputtering. The leakage current density was less than 10 nA/cm2 at 0.5 MV/cm electric field and the dielectric breakdown field was greater than 3.8 MV/cm for P=60%. A charge storage as high as 3.3 μF/cm2 was achieved for 70-Å-thick film. Pulse frequency variation (from 20 to 200 kHz) did not give a significant effect in the electrical properties (dielectric constant or leakage current density) of the Ta2O5 films.

  12. Persistence border collisions in a vibrating system excited by an unbalanced motor with a relay control

    NASA Astrophysics Data System (ADS)

    Zhusubaliyev, Zhanybai T.; Avrutin, Viktor; Rubanov, Vasily G.; Bushuev, Dmitry A.; Titov, Dmitry V.; Yanochkina, Olga O.

    2018-05-01

    The paper describes a new scenario for the transition to complex dynamics in a vibrating system with an unbalanced rotor and a relay feedback control. We show that the transition from a regular dynamics without switching events in the relay element to an irregular dynamics which takes place completely in the hysteresis region occurs via a cascade of persistence border collisions.

  13. Recurrence, submicroscopic complexity, and potential clinical relevance of copy gains detected by array CGH that are shown to be unbalanced insertions by FISH.

    PubMed

    Neill, Nicholas J; Ballif, Blake C; Lamb, Allen N; Parikh, Sumit; Ravnan, J Britt; Schultz, Roger A; Torchia, Beth S; Rosenfeld, Jill A; Shaffer, Lisa G

    2011-04-01

    Insertions occur when a segment of one chromosome is translocated and inserted into a new region of the same chromosome or a non-homologous chromosome. We report 71 cases with unbalanced insertions identified using array CGH and FISH in 4909 cases referred to our laboratory for array CGH and found to have copy-number abnormalities. Although the majority of insertions were non-recurrent, several recurrent unbalanced insertions were detected, including three der(Y)ins(Y;18)(q?11.2;p11.32p11.32)pat inherited from parents carrying an unbalanced insertion. The clinical significance of these recurrent rearrangements is unclear, although the small size, limited gene content, and inheritance pattern of each suggests that the phenotypic consequences may be benign. Cryptic, submicroscopic duplications were observed at or near the insertion sites in two patients, further confounding the clinical interpretation of these insertions. Using FISH, linear amplification, and array CGH, we identified a 126-kb duplicated region from 19p13.3 inserted into MECP2 at Xq28 in a patient with symptoms of Rett syndrome. Our results demonstrate that although the interpretation of most non-recurrent insertions is unclear without high-resolution insertion site characterization, the potential for an otherwise benign duplication to result in a clinically relevant outcome through the disruption of a gene necessitates the use of FISH to determine whether copy-number gains detected by array CGH represent tandem duplications or unbalanced insertions. Further follow-up testing using techniques such as linear amplification or sequencing should be used to determine gene involvement at the insertion site after FISH has identified the presence of an insertion.

  14. Future missions for observing Earth's changing gravity field: a closed-loop simulation tool

    NASA Astrophysics Data System (ADS)

    Visser, P. N.

    2008-12-01

    The GRACE mission has successfully demonstrated the observation from space of the changing Earth's gravity field at length and time scales of typically 1000 km and 10-30 days, respectively. Many scientific communities strongly advertise the need for continuity of observing Earth's gravity field from space. Moreover, a strong interest is being expressed to have gravity missions that allow a more detailed sampling of the Earth's gravity field both in time and in space. Designing a gravity field mission for the future is a complicated process that involves making many trade-offs, such as trade-offs between spatial, temporal resolution and financial budget. Moreover, it involves the optimization of many parameters, such as orbital parameters (height, inclination), distinction between which gravity sources to observe or correct for (for example are gravity changes due to ocean currents a nuisance or a signal to be retrieved?), observation techniques (low-low satellite-to-satellite tracking, satellite gravity gradiometry, accelerometers), and satellite control systems (drag-free?). A comprehensive tool has been developed and implemented that allows the closed-loop simulation of gravity field retrievals for different satellite mission scenarios. This paper provides a description of this tool. Moreover, its capabilities are demonstrated by a few case studies. Acknowledgments. The research that is being done with the closed-loop simulation tool is partially funded by the European Space Agency (ESA). An important component of the tool is the GEODYN software, kindly provided by NASA Goddard Space Flight Center in Greenbelt, Maryland.

  15. Classification of highly unbalanced CYP450 data of drugs using cost sensitive machine learning techniques.

    PubMed

    Eitrich, T; Kless, A; Druska, C; Meyer, W; Grotendorst, J

    2007-01-01

    In this paper, we study the classifications of unbalanced data sets of drugs. As an example we chose a data set of 2D6 inhibitors of cytochrome P450. The human cytochrome P450 2D6 isoform plays a key role in the metabolism of many drugs in the preclinical drug discovery process. We have collected a data set from annotated public data and calculated physicochemical properties with chemoinformatics methods. On top of this data, we have built classifiers based on machine learning methods. Data sets with different class distributions lead to the effect that conventional machine learning methods are biased toward the larger class. To overcome this problem and to obtain sensitive but also accurate classifiers we combine machine learning and feature selection methods with techniques addressing the problem of unbalanced classification, such as oversampling and threshold moving. We have used our own implementation of a support vector machine algorithm as well as the maximum entropy method. Our feature selection is based on the unsupervised McCabe method. The classification results from our test set are compared structurally with compounds from the training set. We show that the applied algorithms enable the effective high throughput in silico classification of potential drug candidates.

  16. Crash Frequency Modeling Using Real-Time Environmental and Traffic Data and Unbalanced Panel Data Models

    PubMed Central

    Chen, Feng; Chen, Suren; Ma, Xiaoxiang

    2016-01-01

    Traffic and environmental conditions (e.g., weather conditions), which frequently change with time, have a significant impact on crash occurrence. Traditional crash frequency models with large temporal scales and aggregated variables are not sufficient to capture the time-varying nature of driving environmental factors, causing significant loss of critical information on crash frequency modeling. This paper aims at developing crash frequency models with refined temporal scales for complex driving environments, with such an effort providing more detailed and accurate crash risk information which can allow for more effective and proactive traffic management and law enforcement intervention. Zero-inflated, negative binomial (ZINB) models with site-specific random effects are developed with unbalanced panel data to analyze hourly crash frequency on highway segments. The real-time driving environment information, including traffic, weather and road surface condition data, sourced primarily from the Road Weather Information System, is incorporated into the models along with site-specific road characteristics. The estimation results of unbalanced panel data ZINB models suggest there are a number of factors influencing crash frequency, including time-varying factors (e.g., visibility and hourly traffic volume) and site-varying factors (e.g., speed limit). The study confirms the unique significance of the real-time weather, road surface condition and traffic data to crash frequency modeling. PMID:27322306

  17. Implementation of Design Changes Towards a More Reliable, Hands-off Magnetron Ion Source

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sosa, A.; Bollinger, D. S.; Karns, P. R.

    As the main H- ion source for the accelerator complex, magnetron ion sources have been used at Fermilab since the 1970’s. At the offline test stand, new R&D is carried out to develop and upgrade the present magnetron-type sources of H- ions of up to 80 mA and 35 keV beam energy in the context of the Proton Improvement Plan. The aim of this plan is to provide high-power proton beams for the experiments at FNAL. In order to reduce the amount of tuning and monitoring of these ion sources, a new electronic system consisting of a current-regulated arc dischargemore » modulator allow the ion source to run at a constant arc current for improved beam output and operation. A solenoid-type gas valve feeds H2 gas into the source precisely and independently of ambient temperature. This summary will cover several studies and design changes that have been tested and will eventually be implemented on the operational magnetron sources at Fermilab. Innovative results for this type of ion source include cathode geometries, solenoid gas valves, current controlled arc pulser, cesium boiler redesign, gas mixtures of hydrogen and nitrogen, and duty factor reduction, with the aim to improve source lifetime, stability, and reducing the amount of tuning needed. In this summary, I will highlight the advances made in ion sources at Fermilab and will outline the directions of the continuing R&D effort.« less

  18. Comparative analysis of electrophysical properties of ceramic tantalum pentoxide coatings, deposited by electron beam evaporation and magnetron sputtering methods

    NASA Astrophysics Data System (ADS)

    Donkov, N.; Mateev, E.; Safonov, V.; Zykova, A.; Yakovin, S.; Kolesnikov, D.; Sudzhanskaya, I.; Goncharov, I.; Georgieva, V.

    2014-12-01

    Ta2O5 ceramic coatings have been deposited on glass substrates by e-beam evaporation and magnetron sputtering methods. For the magnetron sputtering process Ta target was used. X-ray diffraction measurements show that these coatings are amorphous. XPS survey spectra of the ceramic Ta2O5 coatings were obtained. All spectra consist of well-defined XPS lines of Ta 4f, 4d, 4p and 4s; O 1s; C 1s. Ta 4f doublets are typical for Ta2O5 coatings with two main peaks. Scanning electron microscopy and atomic force microscopy images of the e-beam evaporated and magnetron sputtered Ta2O5 ceramic coatings have revealed a relatively flat surface with no cracks. The dielectric properties of the tantalum pentoxide coatings have been investigated in the frequency range of 100 Hz to 1 MHz. The electrical behaviour of e-beam evaporated and magnetron sputtered Ta2O5 ceramic coatings have also been compared. The deposition process conditions principally effect the structure parameters and electrical properties of Ta2O5 ceramic coatings. The coatings deposited by different methods demonstrate the range of dielectric parameters due to the structural and stoichiometric composition changes

  19. Are the argon metastables important in high power impulse magnetron sputtering discharges?

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gudmundsson, J. T., E-mail: tumi@hi.is; Science Institute, University of Iceland, Dunhaga 3, IS-107 Reykjavik; Lundin, D.

    2015-11-15

    We use an ionization region model to explore the ionization processes in the high power impulse magnetron sputtering (HiPIMS) discharge in argon with a titanium target. In conventional dc magnetron sputtering (dcMS), stepwise ionization can be an important route for ionization of the argon gas. However, in the HiPIMS discharge stepwise ionization is found to be negligible during the breakdown phase of the HiPIMS pulse and becomes significant (but never dominating) only later in the pulse. For the sputtered species, Penning ionization can be a significant ionization mechanism in the dcMS discharges, while in the HiPIMS discharge Penning ionization ismore » always negligible as compared to electron impact ionization. The main reasons for these differences are a higher plasma density in the HiPIMS discharge, and a higher electron temperature. Furthermore, we explore the ionization fraction and the ionized flux fraction of the sputtered vapor and compare with recent experimental work.« less

  20. Infrared metamaterial by RF magnetron sputtered ZnO/Al:ZnO multilayers

    NASA Astrophysics Data System (ADS)

    Santiago, Kevin C.; Mundle, Rajeh; White, Curtis; Bahoura, Messaoud; Pradhan, Aswini K.

    2018-03-01

    Hyperbolic metamaterials create artificial anisotropy using metallic wires suspended in dielectric media or alternating layers of a metal and dielectric (Type I or Type II). In this study we fabricated ZnO/Al:ZnO (AZO) multilayers by the RF magnetron sputtering deposition technique. Our fabricated multilayers satisfy the requirements for a type II hyperbolic metamaterial. The optical response of individual AZO and ZnO films, as well as the multilayered film were investigated via UV-vis-IR transmittance and spectroscopic ellipsometry. The optical response of the multilayered system is calculated using the nonlocal-corrected Effective Medium Approximation (EMA). The spectroscopic ellipsometry data of the multilayered system was modeled using a uniaxial material model and EMA model. Both theoretical and experimental studies validate the fabricated multilayers undergo a hyperbolic transition at a wavelength of 2.2 μm. To our knowledge this is the first AZO/ZnO type II hyperbolic metamaterial system fabricated by magnetron sputtering deposition method.

  1. Assumption or Fact? Line-to-Neutral Voltage Expression in an Unbalanced 3-Phase Circuit during Inverter Switching

    ERIC Educational Resources Information Center

    Masrur, M. A.

    2009-01-01

    This paper discusses the situation in a 3-phase motor or any other 3-phase system operating under unbalanced operating conditions caused by an open fault in an inverter switch. A dc voltage source is assumed as the input to the inverter, and under faulty conditions of the inverter switch, the actual voltage applied between the line to neutral…

  2. Recommendations for choosing an analysis method that controls Type I error for unbalanced cluster sample designs with Gaussian outcomes.

    PubMed

    Johnson, Jacqueline L; Kreidler, Sarah M; Catellier, Diane J; Murray, David M; Muller, Keith E; Glueck, Deborah H

    2015-11-30

    We used theoretical and simulation-based approaches to study Type I error rates for one-stage and two-stage analytic methods for cluster-randomized designs. The one-stage approach uses the observed data as outcomes and accounts for within-cluster correlation using a general linear mixed model. The two-stage model uses the cluster specific means as the outcomes in a general linear univariate model. We demonstrate analytically that both one-stage and two-stage models achieve exact Type I error rates when cluster sizes are equal. With unbalanced data, an exact size α test does not exist, and Type I error inflation may occur. Via simulation, we compare the Type I error rates for four one-stage and six two-stage hypothesis testing approaches for unbalanced data. With unbalanced data, the two-stage model, weighted by the inverse of the estimated theoretical variance of the cluster means, and with variance constrained to be positive, provided the best Type I error control for studies having at least six clusters per arm. The one-stage model with Kenward-Roger degrees of freedom and unconstrained variance performed well for studies having at least 14 clusters per arm. The popular analytic method of using a one-stage model with denominator degrees of freedom appropriate for balanced data performed poorly for small sample sizes and low intracluster correlation. Because small sample sizes and low intracluster correlation are common features of cluster-randomized trials, the Kenward-Roger method is the preferred one-stage approach. Copyright © 2015 John Wiley & Sons, Ltd.

  3. Analysis of hourly crash likelihood using unbalanced panel data mixed logit model and real-time driving environmental big data.

    PubMed

    Chen, Feng; Chen, Suren; Ma, Xiaoxiang

    2018-06-01

    Driving environment, including road surface conditions and traffic states, often changes over time and influences crash probability considerably. It becomes stretched for traditional crash frequency models developed in large temporal scales to capture the time-varying characteristics of these factors, which may cause substantial loss of critical driving environmental information on crash prediction. Crash prediction models with refined temporal data (hourly records) are developed to characterize the time-varying nature of these contributing factors. Unbalanced panel data mixed logit models are developed to analyze hourly crash likelihood of highway segments. The refined temporal driving environmental data, including road surface and traffic condition, obtained from the Road Weather Information System (RWIS), are incorporated into the models. Model estimation results indicate that the traffic speed, traffic volume, curvature and chemically wet road surface indicator are better modeled as random parameters. The estimation results of the mixed logit models based on unbalanced panel data show that there are a number of factors related to crash likelihood on I-25. Specifically, weekend indicator, November indicator, low speed limit and long remaining service life of rutting indicator are found to increase crash likelihood, while 5-am indicator and number of merging ramps per lane per mile are found to decrease crash likelihood. The study underscores and confirms the unique and significant impacts on crash imposed by the real-time weather, road surface, and traffic conditions. With the unbalanced panel data structure, the rich information from real-time driving environmental big data can be well incorporated. Copyright © 2018 National Safety Council and Elsevier Ltd. All rights reserved.

  4. Visualization in mechanics: the dynamics of an unbalanced roller

    NASA Astrophysics Data System (ADS)

    Cumber, Peter S.

    2017-04-01

    It is well known that mechanical engineering students often find mechanics a difficult area to grasp. This article describes a system of equations describing the motion of a balanced and an unbalanced roller constrained by a pivot arm. A wide range of dynamics can be simulated with the model. The equations of motion are embedded in a graphical user interface for its numerical solution in MATLAB. This allows a student's focus to be on the influence of different parameters on the system dynamics. The simulation tool can be used as a dynamics demonstrator in a lecture or as an educational tool driven by the imagination of the student. By way of demonstration the simulation tool has been applied to a range of roller-pivot arm configurations. In addition, approximations to the equations of motion are explored and a second-order model is shown to be accurate for a limited range of parameters.

  5. High-efficiency interaction-free measurement with an unbalanced Mach–Zehnder interferometer

    NASA Astrophysics Data System (ADS)

    Chao, Liu; Jinhong, Liu; Junxiang, Zhang; Shiyao, Zhu

    2018-06-01

    The presence of an object can be detected without the absorption of photons in an interaction-free measurement (IFM) system based on the Zeno effect in chained Mach–Zehnder interferometers (MZIs). In this paper, we propose a scheme with an unbalanced MZI to perform the transmission of two frequency components of input light simultaneously. The two components are separated at two output ports of the MZI, achieving a high probability of asserting the absence of the object. The two final outputs of the MZI can also be extended to perform special information processing via IFM. As a result, this proposal contributes to the improvement of efficiency in interaction-free measurements with a very small number of interferometers for potential practical implementations of quantum information technology.

  6. A W-band sixth-harmonic magnetron-type slotted peniotron

    NASA Astrophysics Data System (ADS)

    Hu, Biao; Li, Jiayin; Wu, Xinhui; Li, Tianming; Li, Hao; Wang, Haiyang; Zhao, Xiaoyun

    2013-04-01

    This paper has numerically investigated operating characteristics of a w-band six-harmonic magnetron-type slotted peniotron with 7 vanes. With the new structure design, a high efficiency of 40% w-band 30 kW medium power microwave source has been achieved and the mode competition can be somewhat suppressed. The main advantage of such a peniotron, based on a permanent magnet, is that it can have much more compact size and lower cost, and its operation gap can be greatly reduced.

  7. Effect of residual gas on structural, electrical and mechanical properties of niobium films deposited by magnetron sputtering deposition

    NASA Astrophysics Data System (ADS)

    Wang, Lanruo; Zhong, Yuan; Li, Jinjin; Cao, Wenhui; Zhong, Qing; Wang, Xueshen; Li, Xu

    2018-04-01

    Magnetron sputtering is an important method in the superconducting thin films deposition. The residual gas inside the vacuum chamber will directly affect the quality of the superconducting films. In this paper, niobium films are deposited by magnetron sputtering under different chamber residual gas conditions. The influence of baking and sputtering process on residual gas are studied as well. Surface morphology, electrical and mechanical properties of the films are analysed. The residual gas analysis result before the sputtering process could be regarded as a reference condition to achieve high quality superconducting thin films.

  8. Distribution of magnesium in central nervous system tissue, trabecular and cortical bone in rats fed with unbalanced diets of minerals.

    PubMed

    Yasui, M; Yano, I; Yase, Y; Ota, K

    1990-11-01

    Recent epidemiological changes in patterns of foci of amyotrophic lateral sclerosis (ALS) in the Western Pacific suggest that environmental factors play a contributory role in the pathogenic process of this disorder. In this experimental study on rats, a similar situation of dietary mineral imbalance was created as is found in the soil and drinking water of these ALS foci with a low content of calcium (Ca) and magnesium (Mg) and a high content of aluminum (Al). In groups of rats fed a low Ca diet, low Ca-Mg diet, and low Ca-Mg plus high Al diet, serum Ca levels were found to be lower than those in a group fed a standard diet. Also, serum Mg levels were lower in the groups fed a low Ca-Mg diet and a low Ca-Mg plus high Al diet than in the groups fed a standard diet and only a low Ca diet. There was no significant difference in Mg content of central nervous system (CNS) tissues of groups fed unbalanced and standard diets, except for a significant decrease in Mg content of the spinal cord of rats fed a low Ca-Mg plus high Al diet. Mg content of the lumbar spine and cortical bone decreased in the unbalanced diet groups compared with that of a group fed a standard diet. These findings suggest that under the disturbed bone mineralization induced by unbalanced mineral diets, Mg may be mobilized from bone to maintain the level necessary for vital activity in soft tissues including CNS tissue.

  9. Discharge current modes of high power impulse magnetron sputtering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Wu, Zhongzhen, E-mail: wuzz@pkusz.edu.cn; Xiao, Shu; Ma, Zhengyong

    2015-09-15

    Based on the production and disappearance of ions and electrons in the high power impulse magnetron sputtering plasma near the target, the expression of the discharge current is derived. Depending on the slope, six possible modes are deduced for the discharge current and the feasibility of each mode is discussed. The discharge parameters and target properties are simplified into the discharge voltage, sputtering yield, and ionization energy which mainly affect the discharge plasma. The relationship between these factors and the discharge current modes is also investigated.

  10. New heterogeneous test statistics for the unbalanced fixed-effect nested design.

    PubMed

    Guo, Jiin-Huarng; Billard, L; Luh, Wei-Ming

    2011-05-01

    When the underlying variances are unknown or/and unequal, using the conventional F test is problematic in the two-factor hierarchical data structure. Prompted by the approximate test statistics (Welch and Alexander-Govern methods), the authors develop four new heterogeneous test statistics to test factor A and factor B nested within A for the unbalanced fixed-effect two-stage nested design under variance heterogeneity. The actual significance levels and statistical power of the test statistics were compared in a simulation study. The results show that the proposed procedures maintain better Type I error rate control and have greater statistical power than those obtained by the conventional F test in various conditions. Therefore, the proposed test statistics are recommended in terms of robustness and easy implementation. ©2010 The British Psychological Society.

  11. A review comparing cathodic arcs and high power impulse magnetron sputtering (HiPIMS)

    DOE PAGES

    Anders, André

    2014-09-02

    In this study, high power impulse magnetron sputtering (HiPIMS) has been in the center of attention over the last years as it is an emerging physical vapor deposition (PVD) technology that combines advantages of magnetron sputtering with various forms of energetic deposition of films such as ion plating and cathodic arc plasma deposition. It should not come at a surprise that many extension and variations of HiPIMS make use, intentionally or unintentionally, of previously discovered approaches to film processing such as substrate surface preparation by metal ion sputtering and phased biasing for film texture and stress control. Therefore, in thismore » review, an overview is given on some historical developments and features of cathodic arc and HiPIMS plasmas, showing commonalities and differences. To limit the scope, emphasis is put on plasma properties, as opposed to surveying the vast literature on specific film materials and their properties.« less

  12. Magnetic properties of in-plane oriented barium hexaferrite thin films prepared by direct current magnetron sputtering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhang, Xiaozhi; Yue, Zhenxing, E-mail: yuezhx@mail.tsinghua.edu.cn; Meng, Siqin

    2014-12-28

    In-plane c-axis oriented Ba-hexaferrite (BaM) thin films were prepared on a-plane (112{sup ¯}0) sapphire (Al{sub 2}O{sub 3}) substrates by DC magnetron sputtering followed by ex-situ annealing. The DC magnetron sputtering was demonstrated to have obvious advantages over the traditionally used RF magnetron sputtering in sputtering rate and operation simplicity. The sputtering power had a remarkable influence on the Ba/Fe ratio, the hematite secondary phase, and the grain morphology of the as-prepared BaM films. Under 80 W of sputtering power, in-plane c-axis highly oriented BaM films were obtained. These films had strong magnetic anisotropy with high hysteresis loop squareness (M{sub r}/M{sub s}more » of 0.96) along the in-plane easy axis and low M{sub r}/M{sub s} of 0.03 along the in-plane hard axis. X-ray diffraction patterns and pole figures revealed that the oriented BaM films grew via an epitaxy-like growth process with the crystallographic relationship BaM (101{sup ¯}0)//α-Fe{sub 2}O{sub 3}(112{sup ¯}0)//Al{sub 2}O{sub 3}(112{sup ¯}0)« less

  13. Characterization of barium strontium titanate thin films on sapphire substrate prepared via RF magnetron sputtering system

    NASA Astrophysics Data System (ADS)

    Jamaluddin, F. W.; Khalid, M. F. Abdul; Mamat, M. H.; Zoolfakar, A. S.; Zulkefle, M. A.; Rusop, M.; Awang, Z.

    2018-05-01

    Barium Strontium Titanate (Ba0.5Sr0.5TiO3) is known to have a high dielectric constant and low loss at microwave frequencies. These unique features are useful for many electronic applications. This paper focuses on material characterization of BST thin films deposited on sapphire substrate by RF magnetron sputtering system. The sample was then annealed at 900 °C for two hours. Several methods were used to characterize the structural properties of the material such as X-ray diffraction (XRD) and atomic force microscopy (AFM). Field emission scanning electron microscopy (FESEM) was used to analyze the surface morphology of the thin film. From the results obtained, it can be shown that the annealed sample had a rougher surface and better crystallinity as compared to as-deposited sample.

  14. Performance characterization of a solenoid-type gas valve for the H- magnetron source at FNAL

    NASA Astrophysics Data System (ADS)

    Sosa, A.; Bollinger, D. S.; Karns, P. R.

    2017-08-01

    The magnetron-style H- ion sources currently in operation at Fermilab use piezoelectric gas valves to function. This kind of gas valve is sensitive to small changes in ambient temperature, which affect the stability and performance of the ion source. This motivates the need to find an alternative way of feeding H2 gas into the source. A solenoid-type gas valve has been characterized in a dedicated off-line test stand to assess the feasibility of its use in the operational ion sources. H- ion beams have been extracted at 35 keV using this valve. In this study, the performance of the solenoid gas valve has been characterized measuring the beam current output of the magnetron source with respect to the voltage and pulse width of the signal applied to the gas valve.

  15. Investigation of high power impulse magnetron sputtering (HIPIMS) discharge using fast ICCD camera

    NASA Astrophysics Data System (ADS)

    Hecimovic, Ante

    2012-10-01

    High power impulse magnetron sputtering (HIPIMS) combines impulse glow discharges at power levels up to the MW range with conventional magnetron cathodes to achieve a highly ionised sputtered flux. The dynamics of the HIPIMS discharge was investigated using fast Intensified Charge Coupled Device (ICCD) camera. In the first experiment the HIPIMS plasma was recorded from the side with goal to analyse the plasma intensity using Abel inversion to obtain the emissivity maps of the plasma species. Resulting emissivity maps provide the information on the spatial distribution of Ar and sputtered material and evolution of the plasma chemistry above the cathode. In the second experiment the plasma emission was recorded with camera facing the target. The images show that the HIPIMS plasma develops drift wave type instabilities characterized by well defined regions of high and low plasma emissivity along the racetrack of the magnetron. The instabilities cause periodic shifts in the floating potential. The structures rotate in ExB direction at velocities of 10 kms-1 and frequencies up to 200 kHz. The high emissivity regions comprise Ar and metal ion emission with strong Ar and metal neutral emission depletion. A detailed analysis of the temporal evolution of the saturated instabilities using four consequently triggered fast ICCD cameras is presented. Furthermore working gas pressure and discharge current variation showed that the shape and the speed of the instability strongly depend on the working gas and target material combination. In order to better understand the mechanism of the instability, different optical interference band pass filters (of metal and gas atom, and ion lines) were used to observe the spatial distribution of each species within the instability.

  16. [Effect of niobium nitride on the bonding strength of titanium porcelain by magnetron sputtering].

    PubMed

    Wang, Shu-shu; Zhang, La-bao; Guang, Han-bing; Zhou, Shu; Zhang, Fei-min

    2010-05-01

    To investigate the effect of magnetron sputtered niobium nitride (NbN) on the bonding strength of commercially pure cast titanium (Ti) and low-fusing porcelain (Ti/Vita titankeramik system). Sixty Ti specimens were randomly divided into four groups, group T1, T2, T3 and T4. All specimens of group T1 and T2 were first treated with 120 microm blasted Al2O3 particles, and then only specimens of group T2 were treated with magnetron sputtered NbN film. All specimens of group T3 and T4 were first treated with magnetron sputtered NbN film and then only specimens of group T4 were treated with 120 microm blasted Al2O3 particles. The composition of the deposits were analyzed by X-ray diffraction (XRD). A universal testing machine was used to perform the three-point bending test to evaluate the bonding strength of Ti and porcelain. The microstructure of NbN, the interface of Ti-porcelain and the fractured Ti surface were observed with scanning electron microscopy (SEM) and energy depressive spectrum (EDS), and the results were compared. The XRD results showed that the NbN deposits were cubic crystalline phases. The bonding strength of Ti and porcelain in T1 to T4 group were (27.2+/-0.8), (43.1+/-0.6), (31.4+/-1.0) and (44.9+/-0.6) MPa. These results were analyzed by one-way analysis of variance and differences between groups were compared using least significant difference test. Significant inter-group differences were found among all groups (P<0.05). The results of SEM showed that with treatment of Al2O3 or NbN, alone, pre-cracks were found in the interface of Ti-porcelain, while samples treated with both Al2O3 and NbN had better bond. EDS of Ti-porcelain interface showed oxidation occurred in T1, T2 and T3, but was well controlled in T4. Magnetron sputtered NbN can prevent Ti from being oxidized, and can improve the bonding strength of Ti/Vita titankeramik system. Al2O3 blast can also improve the bonding strength of Ti/Vita titankeramik system.

  17. Analysis of the unbalanced NBI rotation experiments in the ISX-B, PLT and PDX tokamaks

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Stacey, W.M. Jr.; Ryu, C.M.; Malik, M.A.

    1985-07-01

    The recently developed Stacey-Sigmar theory for toroidal momentum confinement, which is based upon neoclassical gyroviscosity, has been applied to the analysis of the unbalanced NBI rotation experiments in ISX-B, PLT and PDX. Measured steady-state rotation velocities, momentum confinement times inferred therefrom and momentum confinement times inferred from rotation decay after termination of NBI were compared with theoretical predictions. Good agreement between theory and experiment was obtained over a wide range of the parameters which enter the theory (R,Z,T,B).

  18. How the IMF By induces a By-component on closed field lines during northward IMF Bz

    NASA Astrophysics Data System (ADS)

    Tenfjord, Paul; Østgaard, Nikolai; Strangeway, Robert J.; Reistad, Jone; Magnus Laundal, Karl; Haaland, Stein; Hesse, Michael; Snekvik, Kristian; Milan, Stephen E.

    2017-04-01

    We describe how the IMF By-component induces a local By-component on closed field lines during northward IMF Bz. The mechanism is the result of high-latitude reconnection on the dayside when IMF By is non-zero. We describe the dynamical process, in which tension on newly reconnected field lines redistribute the open flux asymmetrically between the two hemispheres, which leads to asymmetric energy flow into the lobes. The resulting shear flows change the magnetic field, thereby inducing a By-component on closed field lines. We use a global magnetohydrodynamics model to illustrate the mechanism. The magnetosphere imposes asymmetric forces on the ionosphere, and the effects on the ionospheric flows are characterized by a departure from a symmetric two-cell configuration to the growth of one of the lobe cells, while the other will contract. We also present the associated timescales of the local By-component to a change in the IMF By, by both theoretical arguments and by a superposed epoch analysis between magnetic field measurements from GOES and a list of IMF By reversals. We find that the magnetosphere responds within 10 minutes and reconfigures within 40 minutes.

  19. High power impulse magnetron sputtering and its applications

    NASA Astrophysics Data System (ADS)

    Yan, YUAN; Lizhen, YANG; Zhongwei, LIU; Qiang, CHEN

    2018-04-01

    High power impulse magnetron sputtering (HiPIMS) has attracted a great deal of attention because the sputtered material is highly ionized during the coating process, which has been demonstrated to be advantageous for better quality coating. Therefore, the mechanism of the HiPIMS technique has recently been investigated. In this paper, the current knowledge of HiPIMS is described. We focus on the mechanical properties of the deposited thin film in the latest applications, including hard coatings, adhesion enhancement, tribological performance, and corrosion protection layers. A description of the electrical, optical, photocatalytic, and functional coating applications are presented. The prospects for HiPIMS are also discussed in this work.

  20. Tribological and structural properties of titanium nitride and titanium aluminum nitride coatings deposited with modulated pulsed power magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Ward, Logan

    The demand for economical high-performance materials has brought attention to the development of advanced coatings. Recent advances in high power magnetron sputtering (HPPMS) have shown to improve tribological properties of coatings. These coatings offer increased wear and oxidation resistance, which may facilitate the use of more economical materials in harsh applications. This study demonstrates the use of novel forms of HPPMS, namely modulated pulsed-power magnetron sputtering (MPPMS) and deep oscillation magnetron sputtering (DOMS), for depositing TiN and Ti1-xAlxN tribological coatings on commonly used alloys, such as Ti-6Al-4V and Inconel 718. Both technologies have been shown to offer unique plasma characteristics in the physical vapor deposition (PVD) process. High power pulses lead to a high degree of ionization compared to traditional direct-current magnetron sputtering (DCMS) and pulsed magnetron sputtering (PMS). Such a high degree of ionization was previously only achievable by cathodic arc deposition (CAD); however, CAD can lead to increased macroparticles that are unfavorable in high friction and corrosive environments. MPPMS, DOMS, and other HPPMS techniques offer unique plasma characteristics and have been shown to produce coatings with refined grain structure, improved density, hardness, adhesion, and wear resistance. Using DOMS and MPPMS, TiN and Ti1-xAlxN coatings were deposited using PMS to compare microstructures and tribological performance. For Ti1-xAlxN, two sputtering target compositions, Ti 0.5Al0.5 and Ti0.3Al0.7, were used to evaluate the effects of MPPMS on the coating's composition and tribological properties. Scanning electron microscopy (SEM), transmission electron microscopy (TEM), and X-ray diffraction (XRD) were used to characterize microstructure and crystallographic texture. Several tribological properties were evaluated including: wear rate, coefficient of friction, adhesion, and nanohardness. Results show that substrate

  1. Magnetron Sputtered Molybdenum Oxide for Application in Polymers Solar Cells

    NASA Astrophysics Data System (ADS)

    Sendova-Vassileva, M.; Dikov, Hr; Vitanov, P.; Popkirov, G.; Gergova, R.; Grancharov, G.; Gancheva, V.

    2016-10-01

    Thin films of molybdenum oxide were deposited by radio frequency (RF) magnetron sputtering in Ar from a MoO3 target at different deposition power on glass and silicon substrates. The thickness of the films was determined by profilometer measurements and by ellipsometry. The films were annealed in air at temperatures between 200 and 400°C in air. The optical transmission and reflection spectra were measured. The conductivity of the as deposited and annealed films was determined. The crystal structure was probed by Raman spectroscopy. The oxidation state of the surface was studied by X-ray photoelectron spectroscopy (XPS) spectroscopy. The deposition technique described above was used to experiment with MoOx as a hole transport layer (HTL) in polymer solar cells with bulk hetrojunction active layer, deposited by spin coating. The performance of these layers was compared with poly(3,4-ethylenedioxythiophene):polystyrene sulfonate (PEDOT:PSS), which is the standard material used in this role. The measured current-voltage characteristics of solar cells with the structure glass/ITO/HTL/Poly(3-hexyl)thiophene (P3HT):[6,6]-phenyl-C61- butyric acid methyl ester (PCBM)/Al demonstrate that the studied MoOx layer is a good HTL and leads to comparable characteristics to those with PEDOT:PSS. On the other hand the deposition by magnetron sputtering guarantees reliable and repeatable HTLs.

  2. Investigation of electrical and optical properties of low temperature titanium nitride grown by rf-magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Sosnin, D.; Kudryashov, D.; Mozharov, A.

    2017-11-01

    Titanium nitride is a promising material due to its low resistivity, high hardness and chemical inertness. Titanium nitride (TiN) can be applied as an ohmic contact for n-GaN and rectifying contact for p-GaN and also as a part of perovskite solar cell. A technology of TiN low temperature reactive rf-magnetron sputtering has been developed. Electrical and optical properties of titanium nitride were studied as a function of the rf-power and gas mixture composition. Reflectance and transmittance spectra were measured. Cross-section and surface SEM image were obtained. 250 nm thin films of TiN with a resistivity of 23.6 μOm cm were obtained by rf-magnetron sputtering at low temperature.

  3. Microstructure, mechanical and tribological characterization of CrN/DLC/Cr-DLC multilayer coating with improved adhesive wear resistance

    NASA Astrophysics Data System (ADS)

    Sui, Xudong; Liu, Jinyu; Zhang, Shuaituo; Yang, Jun; Hao, Junying

    2018-05-01

    Adhesive wear is one of the major reasons for the failure of components during various tribological application, especially for rubbing with viscous materials. This study presents CrN/DLC/Cr-DLC multilayer composite coatings prepared on a plasma enhanced chemical vapor deposition (PECVD) device with the close field unbalanced magnetron sputtering ion plating (CFUBMSIP) technique. SEM, XRD and Raman spectroscopy were used to determine the structure of multilayer coatings. It was found that the multilayer coatings are composed by the alternating CrN and DLC layers. Compared with the single CrN coatings, the friction coefficient of the CrN/DLC/Cr-DLC multilayer coating decreases about more than seven times after sliding a distance of 500 m. This helps to reduce the adhesive wear of multilayer coatings. Compared with the single CrN and DLC coating, the wear rate of the CrN/DLC/Cr-DLC multilayer coating is reduced by an order of magnitude to 7.10 × 10-17 (sliding with AISI 440C) and 2.64 × 10-17 (sliding with TC4) m3/(N m). The improved tribological performance of multilayer coatings mainly attributes to the introduction of lubricant DLC and hard support CrN layers, the enhancement of crack propagation inhibition, and the increment of elastic recovery value We (71.49%) by multilayer design method.

  4. Breakdown of the Coulomb friction law in TiC/a-C:H nanocomposite coatings

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Pei, Y. T.; Huizenga, P.; Galvan, D.

    2006-12-01

    Advanced TiC/a-C:H nanocomposite coatings have been produced via reactive deposition in a closed-field unbalanced magnetron sputtering system (Hauzer HTC-1000 or HTC 1200). In this paper, we report on the tribological behavior of TiC/a-C:H nanocomposite coatings in which ultralow friction is tailored with superior wear resistance, two properties often difficult to achieve simultaneously. Tribotests have been performed at room temperature with a ball-on-disk configuration. In situ monitoring of the wear depth of the coated disk together with the wear height of the ball counterpart at nanometer scale reveals that the self-lubricating effects are induced by the formation of transfer films onmore » the surface of the ball counterpart. A remarkable finding is a breakdown of the Coulomb friction law in the TiC/a-C:H nanocomposite coatings. In addition, the coefficient of friction of TiC/a-C:H nanocomposite coatings decreases with decreasing relative humidity. A superior wear resistance of the coated disk at a level of 10{sup -17} m{sup 3}/N m (per lap) has been achieved under the condition of superlow friction and high toughness, both of which require fine TiC nanoparticles (e.g., 2 nm) and a wide matrix separation that must be comparable to the dimensions of the nanoparticles.« less

  5. Gross regional domestic product estimation: Application of two-way unbalanced panel data models to economic growth in East Nusa Tenggara province

    NASA Astrophysics Data System (ADS)

    Wibowo, Wahyu; Sinu, Elisabeth B.; Setiawan

    2017-03-01

    The condition of East Nusa Tenggara Province which recently developed new districts can affect the number of information or data collected become unbalanced. One of the consequences of ignoring the data incompleteness is the estimator become not valid. Therefore, the analysis of unbalanced panel data is very crucial.The aim of this paper is to find the estimation of Gross Regional Domestic Product in East Nusa Tenggara Province using unbalanced panel data regression model for two-way error component which assume random effect model (REM). In this research, we employ Feasible Generalized Least Squares (FGLS) as regression coefficients estimation method. Since variance of the model is unknown, ANOVA method is considered to obtain the variance components in order to construct the variance-covariance matrix. The data used in this research is secondary data taken from Central Bureau of Statistics of East Nusa Tenggara Province in 21 districts period 2004-2013. The predictors are the number of labor over 15 years old (X1), electrification ratios (X2), and local revenues (X3) while Gross Regional Domestic Product based on constant price 2000 is the response (Y). The FGLS estimation result shows that the value of R2 is 80,539% and all the predictors chosen are significantly affect (α = 5%) the Gross Regional Domestic Product in all district of East Nusa Tenggara Province. Those variables are the number of labor over 15 years old (X1), electrification ratios (X2), and local revenues (X3) with 0,22986, 0,090476, and 0,14749 of elasticities, respectively.

  6. Large tangential electric fields in plasmas close to temperature screening

    NASA Astrophysics Data System (ADS)

    Velasco, J. L.; Calvo, I.; García-Regaña, J. M.; Parra, F. I.; Satake, S.; Alonso, J. A.; the LHD team

    2018-07-01

    Low collisionality stellarator plasmas usually display a large negative radial electric field that has been expected to cause accumulation of impurities due to their high charge number. In this paper, two combined effects that can potentially modify this scenario are discussed. First, it is shown that, in low collisionality plasmas, the kinetic contribution of the electrons to the radial electric field can make it negative but small, bringing the plasma close to impurity temperature screening (i.e., to a situation in which the ion temperature gradient is the main drive of impurity transport and causes outward flux); in plasmas of very low collisionality, such as those of the large helical device displaying impurity hole (Ida et al (The LHD Experimental Group) 2009 Phys. Plasmas 16 056111; Yoshinuma et al (The LHD Experimental Group) 2009 Nucl. Fusion 49 062002), screening may actually occur. Second, the component of the electric field that is tangent to the flux surface (in other words, the variation of the electrostatic potential on the flux surface), although smaller than the radial component, has recently been suggested to be an additional relevant drive for radial impurity transport. Here, it is explained that, especially when the radial electric field is small, the tangential magnetic drift has to be kept in order to correctly compute the tangential electric field, that can be larger than previously expected. This can have a strong impact on impurity transport, as we illustrate by means of simulations using the newly developed code kinetic orbit-averaging-solver for stellarators, although it is not enough to explain by itself the behavior of the fluxes in situations like the impurity hole.

  7. Characteristics of Iron-Palladium alloy thin films deposited by magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Chiu, Y.-J.; Shen, C.-Y.; Chang, H.-W.; Jian, S.-R.

    2018-06-01

    The microstructural features, magnetic, nanomechanical properties and wettability behaviors of Iron-Palladium (FePd) alloy thin films are investigated by using X-ray diffraction (XRD), atomic force microscopy (AFM), vibrating sample magnetometer (VSM), nanoindentation and water contact angle (CA) techniques, respectively. The FePd alloy thin films were deposited on glass substrates using a magnetron sputtering system. The post-annealing processes of FePd alloy thin films were carried out at 400 °C and 750 °C and resulted in a significant increase of both the average grain size and surface roughness. The XRD analysis showed that FePd alloy thin films exhibited a predominant (1 1 1) orientation. The magnetic field dependence of magnetization of all FePd thin films are measured at room temperature showed the ferromagnetic characteristics. The nanoindentation with continuous stiffness measurement (CSM) is used to measure the hardness and Young's modulus of present films. The contact angle (θCA) increased with increasing surface roughness. The maximum θCA of 75° was achieved for the FePd alloy thin film after annealing at 750 °C and a surface roughness of 4.2 nm.

  8. Plasma studies of a linear magnetron operating in the range from DC to HiPIMS

    NASA Astrophysics Data System (ADS)

    Anders, André; Yang, Yuchen

    2018-01-01

    Plasma properties of magnetrons have been extensively studied in the past with the focus on small, research-style magnetrons with planar disk targets. In this contribution, we report on plasma diagnostics of a linear magnetron because the linear geometry is widely used in industry and, more importantly here, it provides the unique opportunity to align a linear racetrack section with a streak camera's entrance slit. This allows us to follow the evolution of plasma instabilities, i.e., localized ionization zones or spokes, as they travel along the racetrack. This report greatly extends our more limited and focused study on the structure and velocity of spokes [Anders and Yang, Appl. Phys. Lett. 111, 064103 (2017)]. Following recent plasma potential measurements [Panjan and Anders, J. Appl. Phys. 121, 063302 (2017)], we interpret optical emission information with localized electron heating. We confirm that for low direct current operation, spokes move in the -E ×B direction, and in the opposite direction in the high current mode. Streak images indicate slower spoke velocities near corners compared to spoke velocities in the straight sections of the racetrack. Spoke splitting and merging are observed supporting the interpretation that spoke motion represents a phase velocity of the region of greatest ionization and is not a motion of plasma. Fast camera investigations are supplemented by measurements of the energy distribution functions of ions emitted from the straight and curved regions of the racetrack, showing notable and reproducible differences.

  9. Performance Characterization of a Solenoid-type Gas Valve for the H- Magnetron Source at FNAL

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sosa, A.; Bollinger, D. S.; Karns, P. R.

    2016-09-06

    The magnetron-style H- ion sources currently in operation at Fermilab use piezoelectric gas valves to function. This kind of gas valve is sensitive to small changes in ambient temperature, which affect the stability and performance of the ion source. This motivates the need to find an alternative way of feeding H2 gas into the source. A solenoid-type gas valve has been characterized in a dedicated off-line test stand to assess the feasibility of its use in the operational ion sources. H- ion beams have been extracted at 35 keV using this valve. In this study, the performance of the solenoidmore » gas valve has been characterized measuring the beam current output of the magnetron source with respect to the voltage and pulse width of the signal applied to the gas valve.« less

  10. Unbalanced 2 x 2 Factorial Designs and the Interaction Effect: A Troublesome Combination

    PubMed Central

    2015-01-01

    In this power study, ANOVAs of unbalanced and balanced 2 x 2 datasets are compared (N = 120). Datasets are created under the assumption that H1 of the effects is true. The effects are constructed in two ways, assuming: 1. contributions to the effects solely in the treatment groups; 2. contrasting contributions in treatment and control groups. The main question is whether the two ANOVA correction methods for imbalance (applying Sums of Squares Type II or III; SS II or SS III) offer satisfactory power in the presence of an interaction. Overall, SS II showed higher power, but results varied strongly. When compared to a balanced dataset, for some unbalanced datasets the rejection rate of H0 of main effects was undesirably higher. SS III showed consistently somewhat lower power. When the effects were constructed with equal contributions from control and treatment groups, the interaction could be re-estimated satisfactorily. When an interaction was present, SS III led consistently to somewhat lower rejection rates of H0 of main effects, compared to the rejection rates found in equivalent balanced datasets, while SS II produced strongly varying results. In data constructed with only effects in the treatment groups and no effects in the control groups, the H0 of moderate and strong interaction effects was often not rejected and SS II seemed applicable. Even then, SS III provided slightly better results when a true interaction was present. ANOVA allowed not always for a satisfactory re-estimation of the unique interaction effect. Yet, SS II worked better only when an interaction effect could be excluded, whereas SS III results were just marginally worse in that case. Overall, SS III provided consistently 1 to 5% lower rejection rates of H0 in comparison with analyses of balanced datasets, while results of SS II varied too widely for general application. PMID:25807514

  11. Energetic electron anisotropies in the magnetotail - Identification of open and closed field lines

    NASA Technical Reports Server (NTRS)

    Baker, D. N.; Stone, E. C.

    1976-01-01

    Unidirectional anisotropies in the energetic electron fluxes (E greater than or equal to about 200 keV) have been observed in the earth's magnetotail with the Caltech Electron/Isotope Spectrometer on IMP-8. The anisotropies occur during periods of enhanced fluxes and provide essential information on the topology (open or closed) of the magnetotail field lines which are associated with recently identified acceleration regions.

  12. Optical properties of aluminum-doped zinc oxide films deposited by direct-current pulse magnetron reactive sputtering

    NASA Astrophysics Data System (ADS)

    Gao, Xiao-Yong; Chen, Chao; Zhang, Sa

    2014-03-01

    A series of <103>-oriented aluminum-doped zinc oxide (AZO) films were deposited on glass substrates via direct-current pulse magnetron reactive sputtering at different O2-to-Ar gas flow ratios (GFRs). The optical properties of the films were characterized using the fitted optical constants in the general oscillator model (which contains two Psemi-Tri oscillators) through the use of measured ellipsometric parameters. The refractive index dispersion data below the interband absorption edge were analyzed using a single-oscillator model. The fitted optical energy gap obtained using the single-oscillator model clearly shows a blue shift, followed by a red shift, as the GFR increases from 0.9/18 to 2.1/18. This shift can be attributed to the change in the free electron concentration of the film, which is closely related to the film stress. In addition, the fitted β value indicates that the AZO film falls under the ionic class. The photoluminescence spectrum indicates a photoluminescence mechanism of the direct and wide energy gap semiconductor.

  13. Quantum Physics, Fields and Closed Timelike Curves: The D-CTC Condition in Quantum Field Theory

    NASA Astrophysics Data System (ADS)

    Tolksdorf, Jürgen; Verch, Rainer

    2018-01-01

    The D-CTC condition has originally been proposed by David Deutsch as a condition on states of a quantum communication network that contains "backward time-steps" in some of its branches. It has been argued that this is an analogue for quantum processes in the presence of closed timelike curves (CTCs). The unusual properties of states of quantum communication networks that fulfill the D-CTC condition have been discussed extensively in recent literature. In this work, the D-CTC condition is investigated in the framework of quantum field theory in the local, operator-algebraic approach due to Haag and Kastler. It is shown that the D-CTC condition cannot be fulfilled in states that are analytic in the energy, or satisfy the Reeh-Schlieder property, for a certain class of processes and initial conditions. On the other hand, if a quantum field theory admits sufficiently many uncorrelated states across acausally related spacetime regions (as implied by the split property), then the D-CTC condition can always be fulfilled approximately to arbitrary precision. As this result pertains to quantum field theory on globally hyperbolic spacetimes where CTCs are absent, one may conclude that interpreting the D-CTC condition as characteristic for quantum processes in the presence of CTCs could be misleading, and should be regarded with caution. Furthermore, a construction of the quantized massless Klein-Gordon field on the Politzer spacetime, often viewed as spacetime analogue for quantum communication networks with backward time-steps, is proposed in this work.

  14. Demonstration of a vectorial optical field generator with adaptive close loop control.

    PubMed

    Chen, Jian; Kong, Lingjiang; Zhan, Qiwen

    2017-12-01

    We experimentally demonstrate a vectorial optical field generator (VOF-Gen) with an adaptive close loop control. The close loop control capability is illustrated with the calibration of polarization modulation of the system. To calibrate the polarization ratio modulation, we generate 45° linearly polarized beam and make it propagate through a linear analyzer whose transmission axis is orthogonal to the incident beam. For the retardation calibration, circularly polarized beam is employed and a circular polarization analyzer with the opposite chirality is placed in front of the CCD as the detector. In both cases, the close loop control automatically changes the value of the corresponding calibration parameters in the pre-set ranges to generate the phase patterns applied to the spatial light modulators and records the intensity distribution of the output beam by the CCD camera. The optimized calibration parameters are determined corresponding to the minimum total intensity in each case. Several typical kinds of vectorial optical beams are created with and without the obtained calibration parameters, and the full Stokes parameter measurements are carried out to quantitatively analyze the polarization distribution of the generated beams. The comparisons among these results clearly show that the obtained calibration parameters could remarkably improve the accuracy of the polarization modulation of the VOF-Gen, especially for generating elliptically polarized beam with large ellipticity, indicating the significance of the presented close loop in enhancing the performance of the VOF-Gen.

  15. Pd-catalysts for DFAFC prepared by magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Bieloshapka, I.; Jiricek, P.; Vorokhta, M.; Tomsik, E.; Rednyk, A.; Perekrestov, R.; Jurek, K.; Ukraintsev, E.; Hruska, K.; Romanyuk, O.; Lesiak, B.

    2017-10-01

    Samples of a palladium catalyst for direct formic acid fuel cell (DFAFC) applications were prepared on the Elat® carbon cloth by magnetron sputtering. The quantity of Pd was equal to 3.6, 120 and 720 μg/cm2. The samples were tested in a fuel cell for electro-oxidation of formic acid, and were characterized by atomic force microscopy (AFM), scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS). The XPS measurements revealed a high contribution of PdCx phase formed at the Pd/Elat® surface interface, with carbon concentration in PdCx from x = 9.9-14.6 at.%, resulting from the C substrate and CO residual gases. Oxygen groups, e.g. hydroxyl (-OH), carbonyl (Cdbnd O) and carboxyl (COOH), resulted from the synthesis conditions due to the presence of residual gases, electro-oxidation during the reaction and oxidation in the atmosphere. Because of the formation of CO and CO2 on the catalysts during the reaction, or because of poisoning by impurities containing the -CH3 group, together with the risk of Pd losses due to dissolution in formic acid, there was a negative effect of catalyst degradation on the active area surface. The effect of different loadings of Pd layers led to increasing catalyst efficiency. Current-voltage curves showed that different amounts of catalyst did not increase the DFAFC power to a great extent. One reason for this was the catalyst structure formed on the carbon cloth. AFM and SEM measurements showed a layer-by-layer growth with no significant variations in morphology. The results for electric power recalculated for the Pd loading per 1 mg of catalyst layers in comparison to carbon substrates decorated by Pd nanoparticles showed that there is potential for applying anodes for formic acid fuel cells prepared by magnetron sputtering.

  16. Enhanced tunability of magnetron sputtered Ba0.5Sr0.5TiO3 thin films on c-plane sapphire substrates

    NASA Astrophysics Data System (ADS)

    Fardin, E. A.; Holland, A. S.; Ghorbani, K.; Reichart, P.

    2006-07-01

    Thin films of Ba0.5Sr0.5TiO3 (BST) were deposited on c-plane (0001) sapphire by rf magnetron sputtering and investigated by complementary materials analysis methods. Microwave properties of the films, including tunability and Q factor were measured from 1to20GHz by patterning interdigital capacitors (IDCs) on the film surface. The tunability is correlated with texture, strain, and grain size in the deposited films. An enhanced capacitance tunability of 56% at a bias field of 200kV/cm and total device Q of more than 15 (up to 20GHz) were achieved following postdeposition annealing at 900°C.

  17. The nanostructure of porous cobalt coatings deposited by magnetron sputtering in helium atmosphere.

    PubMed

    Lacroix, B; Godinho, V; Fernández, A

    2018-05-01

    In this work, (scanning) transmission electron microscopy has been used to study the nanostructure of porous cobalt coatings obtained by magnetron sputtering using helium as process gas. This nanostructure consists of closed pores of different nanometric size (about 4-20 nm) that are distributed all over a nanocrystalline Co matrix and filled with the deposition gas. Spatially resolved electron energy-loss spectroscopy analysis was applied to measure and map, with high lateral resolution, the relevant physical properties (density, pressure and He-K edge shift) of helium trapped inside these individual nanopores, in order to provide new insights about the growth mechanism involved in such systems. In particular, a coefficient of proportionality, C = 0.039 eV nm 3 , between the blue shift of the He K-edge and the He density has been found. In addition, very high He densities (10-100 at./nm 3 ) and pressures in the gigapascal range (0.05-5.0 GPa) have been measured. The linear dependence of these parameters as a function of the inverse radii obeying to the Laplace-Young law for most of the pores suggests that their formation during the coating's growth takes place in regime of elastic deformation of the Co matrix. Copyright © 2018 Elsevier Ltd. All rights reserved.

  18. Green-wave control of an unbalanced two-route traffic system with signals

    NASA Astrophysics Data System (ADS)

    Tobita, Kazuhiro; Nagatani, Takashi

    2013-11-01

    We introduce the preference parameter into the two-route dynamic model proposed by Wahle et al. The parameter represents the driver’s preference for the route choice. When the driver prefers a route, the traffic flow on route A does not balance with that on route B. We study the signal control for the unbalanced two-route traffic flow at the tour-time feedback strategy where the vehicles move ahead through a series of signals. The traffic signals are controlled by both cycle time and phase shift (offset time). We find that the mean tour time can be balanced by selecting the offset time successfully. We derive the relationship between the mean tour time and offset time (phase shift). Also, the dependences of the mean density and mean current on the offset time are derived.

  19. Reactive sputtering of δ-ZrH{sub 2} thin films by high power impulse magnetron sputtering and direct current magnetron sputtering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Högberg, Hans, E-mail: hans.hogberg@liu.se; Tengdelius, Lina; Eriksson, Fredrik

    2014-07-01

    Reactive sputtering by high power impulse magnetron sputtering (HiPIMS) and direct current magnetron sputtering (DCMS) of a Zr target in Ar/H{sub 2} plasmas was employed to deposit Zr-H films on Si(100) substrates, and with H content up to 61 at. % and O contents typically below 0.2 at. % as determined by elastic recoil detection analysis. X-ray photoelectron spectroscopy reveals a chemical shift of ∼0.7 eV to higher binding energies for the Zr-H films compared to pure Zr films, consistent with a charge transfer from Zr to H in a zirconium hydride. X-ray diffraction shows that the films are single-phase δ-ZrH{sub 2} (CaF{submore » 2} type structure) at H content >∼55 at. % and pole figure measurements give a 111 preferred orientation for these films. Scanning electron microscopy cross-section images show a glasslike microstructure for the HiPIMS films, while the DCMS films are columnar. Nanoindentation yield hardness values of 5.5–7 GPa for the δ-ZrH{sub 2} films that is slightly harder than the ∼5 GPa determined for Zr films and with coefficients of friction in the range of 0.12–0.18 to compare with the range of 0.4–0.6 obtained for Zr films. Wear resistance testing show that phase-pure δ-ZrH{sub 2} films deposited by HiPIMS exhibit up to 50 times lower wear rate compared to those containing a secondary Zr phase. Four-point probe measurements give resistivity values in the range of ∼100–120 μΩ cm for the δ-ZrH{sub 2} films, which is slightly higher compared to Zr films with values in the range 70–80 μΩ cm.« less

  20. Vibration signal correction of unbalanced rotor due to angular speed fluctuation

    NASA Astrophysics Data System (ADS)

    Cao, Hongrui; He, Dong; Xi, Songtao; Chen, Xuefeng

    2018-07-01

    The rotating speed of a rotor is hardly constant in practice due to angular speed fluctuation, which affects the balancing accuracy of the rotor. In this paper, the effect of angular speed fluctuation on vibration responses of the unbalanced rotor is analyzed quantitatively. Then, a vibration signal correction method based on zoom synchrosqueezing transform (ZST) and tacholess order tracking is proposed. The instantaneous angular speed (IAS) of the rotor is extracted by the ZST firstly and then used to calculate the instantaneous phase. The vibration signal is further resampled in angular domain to reduce the effect of angular speed fluctuation. The signal obtained in angular domain is transformed into order domain using discrete Fourier transform (DFT) to estimate the amplitude and phase of the vibration signal. Simulated and experimental results show that the proposed method can successfully correct the amplitude and phase of the vibration signal due to angular speed fluctuation.

  1. Microwave window breakdown experiments and simulations on the UM/L-3 relativistic magnetron

    NASA Astrophysics Data System (ADS)

    Hoff, B. W.; Mardahl, P. J.; Gilgenbach, R. M.; Haworth, M. D.; French, D. M.; Lau, Y. Y.; Franzi, M.

    2009-09-01

    Experiments have been performed on the UM/L-3 (6-vane, L-band) relativistic magnetron to test a new microwave window configuration designed to limit vacuum side breakdown. In the baseline case, acrylic microwave windows were mounted between three of the waveguide coupling cavities in the anode block vacuum housing and the output waveguides. Each of the six 3 cm deep coupling cavities is separated from its corresponding anode cavity by a 1.75 cm wide aperture. In the baseline case, vacuum side window breakdown was observed to initiate at single waveguide output powers close to 20 MW. In the new window configuration, three Air Force Research Laboratory-designed, vacuum-rated directional coupler waveguide segments were mounted between the coupling cavities and the microwave windows. The inclusion of the vacuum side power couplers moved the microwave windows an additional 30 cm away from the anode apertures. Additionally, the Lucite microwave windows were replaced with polycarbonate windows and the microwave window mounts were redesigned to better maintain waveguide continuity in the region around the microwave windows. No vacuum side window breakdown was observed in the new window configuration at single waveguide output powers of 120+MW (a factor of 3 increase in measured microwave pulse duration and factor of 3 increase in measured peak power over the baseline case). Simulations were performed to investigate likely causes for the window breakdown in the original configuration. Results from these simulations have shown that in the original configuration, at typical operating voltage and magnetic field ranges, electrons emitted from the anode block microwave apertures strike the windows with a mean kinetic energy of 33 keV with a standard deviation of 14 keV. Calculations performed using electron impact angle and energy data predict a first generation secondary electron yield of 65% of the primary electron population. The effects of the primary aperture electron

  2. Dewetting kinetics of metallic liquid films: Competition between unbalanced Young's force and dissolutive reaction

    NASA Astrophysics Data System (ADS)

    Lu, Gui; Lin, Lin; Hui, Sheng; Wang, Shuo-Lin; Wang, Xiao-Dong; Lee, Duu-Jong

    2017-11-01

    Dewetting kinetics of Al and NiAl metallic liquid films on NiAl (1 0 0) substrates was studied using molecular dynamics simulations. A new dewetting-spreading transitional behavior was observed for high temperature dewetting. The dewetting-spreading transition comes from the competition between unbalanced Young's force and dissolutive reaction. Without dissolutive reaction, liquid films keep dewetting, but immediately turn into spreading when the dissolutive reaction involved. The dissolutive reaction depends on the initial Ni atom contents rather than the contact areas of dewetting films. The far-away-from saturated Ni content is the main mechanism which accelerates the wetting and reverses the dewetting process at high temperatures.

  3. Synthesis and characterization of CdTe nanostructures grown by RF magnetron sputtering method

    NASA Astrophysics Data System (ADS)

    Akbarnejad, Elaheh; Ghoranneviss, Mahmood; Hantehzadeh, Mohammad Reza

    2017-08-01

    In this paper, we synthesize Cadmium Telluride nanostructures by radio frequency (RF) magnetron sputtering system on soda lime glass at various thicknesses. The effect of CdTe nanostructures thickness on crystalline, optical and morphological properties has been studied by means of X-ray diffraction (XRD), UV-VIS-NIR spectrophotometry, field emission scanning electron microscopy (FESEM) and atomic force microscopy (AFM), respectively. The XRD parameters of CdTe nanostructures such as microstrain, dislocation density, and crystal size have been examined. From XRD analysis, it could be assumed that increasing deposition time caused the formation of the wurtzite hexagonal structure of the sputtered films. Optical properties of the grown nanostructures as a function of film thickness have been observed. All the films indicate more than 60% transmission over a wide range of wavelengths. The optical band gap values of the films have obtained in the range of 1.62-1.45 eV. The results indicate that an RF sputtering method succeeded in depositing of CdTe nanostructures with high purity and controllable physical properties, which is appropriate for photovoltaic and nuclear detector applications.

  4. Cluster randomised crossover trials with binary data and unbalanced cluster sizes: application to studies of near-universal interventions in intensive care.

    PubMed

    Forbes, Andrew B; Akram, Muhammad; Pilcher, David; Cooper, Jamie; Bellomo, Rinaldo

    2015-02-01

    Cluster randomised crossover trials have been utilised in recent years in the health and social sciences. Methods for analysis have been proposed; however, for binary outcomes, these have received little assessment of their appropriateness. In addition, methods for determination of sample size are currently limited to balanced cluster sizes both between clusters and between periods within clusters. This article aims to extend this work to unbalanced situations and to evaluate the properties of a variety of methods for analysis of binary data, with a particular focus on the setting of potential trials of near-universal interventions in intensive care to reduce in-hospital mortality. We derive a formula for sample size estimation for unbalanced cluster sizes, and apply it to the intensive care setting to demonstrate the utility of the cluster crossover design. We conduct a numerical simulation of the design in the intensive care setting and for more general configurations, and we assess the performance of three cluster summary estimators and an individual-data estimator based on binomial-identity-link regression. For settings similar to the intensive care scenario involving large cluster sizes and small intra-cluster correlations, the sample size formulae developed and analysis methods investigated are found to be appropriate, with the unweighted cluster summary method performing well relative to the more optimal but more complex inverse-variance weighted method. More generally, we find that the unweighted and cluster-size-weighted summary methods perform well, with the relative efficiency of each largely determined systematically from the study design parameters. Performance of individual-data regression is adequate with small cluster sizes but becomes inefficient for large, unbalanced cluster sizes. When outcome prevalences are 6% or less and the within-cluster-within-period correlation is 0.05 or larger, all methods display sub-nominal confidence interval coverage

  5. Localized traveling ionization zones and their importance for the high power impulse magnetron sputtering process

    NASA Astrophysics Data System (ADS)

    Maszl, Christian

    2016-09-01

    High power impulse magnetron sputtering (HiPIMS) is a technique to deposit thin films with superior quality. A high ionization degree up to 90% and the natural occurence of high energetic metal ions are the reason why HiPIMS exceeds direct current magnetron sputtering in terms of coating quality. On the other hand HiPIMS suffers from a reduced efficiency, especially if metal films are produced. Therefore, a lot of research is done by experimentalists and theoreticians to clarify the transport mechanisms from target to substrate and to identify the energy source of the energetic metal ions. Magnetron plasmas are prone to a wide range of wave phenomena and instabilities. Especially, during HiPIMS at elevated power/current densities, symmetry breaks and self-organization in the plasma torus are observed. In this scenario localized travelling ionization zones with certain quasi-mode numbers are present which are commonly referred to as spokes. Because of their high rotation speed compared to typical process times of minutes their importance for thin film deposition was underestimated at first. Recent investigations show that spokes have a strong impact on particle transport, are probably the source of the high energetic metal ions and are therefore the essence of HiPIMS plasmas. In this contribution we will describe the current understanding of spokes, discuss implications for thin film synthesis and highlight open questions. This project is supported by the DFG (German Science Foundation) within the framework of the Coordinated Research Center SFB-TR 87 and the Research Department ``Plasmas with Complex Interactions'' at Ruhr-University Bochum.

  6. Optimal SVM parameter selection for non-separable and unbalanced datasets.

    PubMed

    Jiang, Peng; Missoum, Samy; Chen, Zhao

    2014-10-01

    This article presents a study of three validation metrics used for the selection of optimal parameters of a support vector machine (SVM) classifier in the case of non-separable and unbalanced datasets. This situation is often encountered when the data is obtained experimentally or clinically. The three metrics selected in this work are the area under the ROC curve (AUC), accuracy, and balanced accuracy. These validation metrics are tested using computational data only, which enables the creation of fully separable sets of data. This way, non-separable datasets, representative of a real-world problem, can be created by projection onto a lower dimensional sub-space. The knowledge of the separable dataset, unknown in real-world problems, provides a reference to compare the three validation metrics using a quantity referred to as the "weighted likelihood". As an application example, the study investigates a classification model for hip fracture prediction. The data is obtained from a parameterized finite element model of a femur. The performance of the various validation metrics is studied for several levels of separability, ratios of unbalance, and training set sizes.

  7. The effect of changing the magnetic field strength on HiPIMS deposition rates

    NASA Astrophysics Data System (ADS)

    Bradley, J. W.; Mishra, A.; Kelly, P. J.

    2015-06-01

    The marked difference in behaviour between HiPIMS and conventional dc or pulsed-dc magnetron sputtering discharges with changing magnetic field strengths is demonstrated through measurements of deposition rate. To provide a comparison between techniques the same circular magnetron was operated in the three excitation modes at a fixed average power of 680 W and a pressure of 0.54 Pa in the non-reactive sputtering of titanium. The total magnetic field strength B at the cathode surface in the middle of the racetrack was varied from 195 to 380 G. DC and pulsed-dc discharges show the expected behaviour that deposition rates fall with decreasing B (here by ~25-40%), however the opposite trend is observed in HiPIMS with deposition rates rising by a factor of 2 over the same decrease in B. These observations are understood from the stand point of the different composition and transport processes of the depositing metal flux between the techniques. In HiPIMS, this flux is largely ionic and slow post-ionized sputtered particles are subject to strong back attraction to the target by a retarding plasma potential structure ahead of them. The height of this potential barrier is known to increase with increasing B. From a simple phenomenological model of the sputtered particles fluxes, and using the measured deposition rates from the different techniques as inputs, the combined probabilities of ionization, α, and back attraction, β, of the metal species in HiPIMS has been calculated. There is a clear fall in αβ (from ~0.9 to ~0.7) with decreasing B-field strengths, we argue primarily due to a weakening of electrostatic ion back attraction, so leading to higher deposition rates. The results indicate that careful design of magnetron field strengths should be considered to optimise HiPIMS deposition rates.

  8. Mn-coatings on the micro-pore formed Ti-29Nb-xHf alloys by RF-magnetron sputtering for dental applications

    NASA Astrophysics Data System (ADS)

    Park, Seon-Yeong; Choe, Han-Cheol

    2018-02-01

    In this study, Mn-coatings on the micro-pore formed Ti-29Nb-xHf alloys by RF-magnetrons sputtering for dental applications were studied using different experimental techniques. Mn coating films were formed on Ti-29Nb-xHf alloys by a radio frequency magnetron sputtering technique for 0, 1, 3, and 5 min at 45 W. The microstructure, composition, and phase structure of the coated alloys were examined by optical microscopy, field emission scanning electron microscopy, X-ray diffraction, and energy-dispersive X-ray spectroscopy. The microstructure of Ti-29Nb alloy showed α" phase in the needle-like structure and Ti-29Nb-15Hf alloy showed β phase in the equiaxed structure. As the sputtering time increased, the circular particles of Mn coatings on the Ti-29Nb alloy increased at inside and outside surfaces. As the sputtering time increased, [Mn + Ca/P] ratio of the plasma electrolytic oxidized films in Ti- 29Nb-xHf alloys increased. The corrosion potential (Ecorr) of Mn coatings on the Ti-29Nb alloy showed higher than that of Mn coatings on the Ti-29Nb-15Hf alloy. The passive current density (Ipass) of the Mn coating on the Ti-29Nb alloy and Mn coatings on the Ti-29Nb-15Hf alloy was less noble than the non-Mn coated Ti-29Nb and Ti-29Nb-15Hf alloys surface.

  9. Nanoscale Cu{sub 2}O films: Radio-frequency magnetron sputtering and structural and optical studies

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kudryashov, D. A., E-mail: kudryashovda@apbau.ru; Gudovskikh, A. S.; Babichev, A. V.

    2017-01-15

    Nanoscale copper (I) oxide layers are formed by magnetron-assisted sputtering onto glassy and silicon substrates in an oxygen-free environment at room temperature, and the structural and optical properties of the layers are studied. It is shown that copper oxide formed on a silicon substrate exhibits a lower degree of disorder than that formed on a glassy substrate, which is supported by the observation of a higher intensity and a smaller half-width of reflections in the diffraction pattern. The highest intensity of reflections in the diffraction pattern is observed for Cu{sub 2}O films grown on silicon at a magnetron power ofmore » 150 W. The absorption and transmittance spectra of these Cu{sub 2}O films are in agreement with the well-known spectra of bulk crystals. In the Raman spectra of the films, phonons inherent in the crystal lattice of cubic Cu{sub 2}O crystals are identified.« less

  10. Study of cobalt mononitride thin films prepared using DC and high power impulse magnetron sputtering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gupta, Rachana, E-mail: dr.rachana.gupta@gmail.com; Pandey, Nidhi; Behera, Layanta

    2016-05-23

    In this work we studied cobalt mononitride (CoN) thin films deposited using dc magnetron sputtering (dcMS) and high power impulse magnetron sputtering (HiPIMS). A Co target was sputtered using pure N{sub 2} gas alone as the sputtering medium. Obtained long-range structural ordering was studies using x-ray diffraction (XRD), short-range structure using Co L{sub 2,3} and N K absorption edges using soft x-ray absorption spectroscopy (XAS) and the surface morphology using atomic force microscopy (AFM). It was found that HiPIMS deposited films have better long-range ordering, better stoichiometric ratio for mononitride composition and smoother texture as compared to dcMS deposited films.more » In addition, the thermal stability of HiPIMS deposited CoN film seems to be better. On the basis of different type of plasma conditions generated in HiPIMS and dcMS process, obtained results are presented and discussed.« less

  11. Is classic pericentric inversion of chromosome 2 inv(2)(p11q13) associated with an increased risk of unbalanced chromosomes?

    PubMed

    Ferfouri, Fatma; Clement, Patrice; Gomes, Denise Molina; Minz, Marie; Amar, Edouard; Selva, Jacqueline; Vialard, François

    2009-10-01

    To study pericentric inversion segregation and interchromosomal effect on sperm for men heterozygous for inv(2)(p11q13), to assess the risk of miscarriage. Case report. Department of reproductive biology, cytogenetics, gynecology, and obstetrics. Seven patients heterozygous for inv(2)(p11q13) and five patients with normal karyotype with experience of recurrent spontaneous miscarriage. Fluorescence in situ hybridization on sperm with 2 p and 2q subtelomeric probes to screen for inversion segregation, and X, Y, and 18 centromeric probes to study interchromosomal effects. One thousand sperm were analyzed per experiment and per patient. Rate of unbalanced chromosomes and aneuploid sperm. The inv(2)(p11q13) patients showed a 0.3% rate of sperm with unbalanced chromosomes. For interchromosomal effects, a 0.6% aneuploid sperm rate was observed for patients heterozygous for inv(2)(p11q13). This is similar to the 0.5% rate observed for control patients. Inv(2)(p11q13) seems not to increase miscarriage for couples with men heterozygous for this inversion.

  12. Photoluminescence of ZnS-SiO2:Ce Thin Films Deposited by Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    Mizuno, Masao

    2011-12-01

    Photoluminescent emissions of zinc sulfide-silica-cerium thin films deposited by magnetron sputtering were observed. The films consisted of ZnS nanocrystals embedded in amorphous SiO2 matrices. ZnS-SiO2:Ce films exhibited photoluminescence even without postannealing. Their emission spectra showed broad patterns in the visible range; the emitted colors depended on film composition.

  13. Applying PWM to control overcurrents at unbalanced faults of force-commutated VSCs used as static var compensators

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jiang, Y.; Ekstroem, A.

    1997-01-01

    This study is devoted to investigating the possibility of controlling the overcurrent of a forced-commutated voltage source converter (VSC) by PWM when the ac system is undergoing large unbalanced disturbance. The converter is supposed to be used as a static var compensator at a high power level. A novel control strategy is proposed for controlling the reactive current and the dc side voltage independently. Digital simulation results are presented and compared with the results by using just the reactive current control with fundamental switching frequency.

  14. Fabrication of eco-friendly PNP transistor using RF magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Kumar, B. Santhosh; Harinee, N.; Purvaja, K.; Shanker, N. Praveen; Manikandan, M.; Aparnadevi, N.; Mukilraj, T.; Venkateswaran, C.

    2018-05-01

    An effort has been made to fabricate a thin film transistor using eco-friendly oxide semiconductor materials. Oxide semiconductor materials are cost - effective, thermally and chemically stable with high electron/hole mobility. Copper (II) oxide is a p-type semiconductor and zinc oxide is an n-type semiconductor. A pnp thin film transistor was fabricated using RF magnetron sputtering. The films deposited have been subjected to structural characterization using AFM. I-V characterization of the fabricated device, Ag/CuO/ZnO/CuO/Ag, confirms transistor behaviour. The mechanism of electron/hole transport of the device is discussed below.

  15. Measured close lightning leader-step electric-field-derivative waveforms.

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jordan, Doug M.; Hill, Dustin; Biagi, Christopher J.

    2010-12-01

    We characterize the measured electric field-derivative (dE/dt) waveforms of lightning stepped-leader steps from three negative lightning flashes at distances of tens to hundreds of meters. Electromagnetic signatures of leader steps at such close distances have rarely been documented in previous literature. Individual leader-step three-dimensional locations are determined by a dE/dt TOA system. The leader-step field derivative is typically a bipolar pulse with a sharp initial half-cycle of the same polarity as that of the return stroke, followed by an opposite polarity overshoot that decays relatively slowly to background level. This overshoot increases in amplitude relative to the initial peak andmore » becomes dominant as range decreases. The initial peak is often preceded by a 'slow front,' similar to the slow front that precedes the fast transition to peak in first return stroke dE/dt and E waveforms. The overall step-field waveform duration is typically less than 1 {micro}s. The mean initial peak of dE/dt, range-normalized to 100 km, is 7.4 V m{sup -1} {micro}s{sup -1} (standard deviation (S.D.), 3.7 V m{sup -1} {micro}s{sup -1}, N = 103), the mean half-peak width is 33.5 ns (S.D., 11.9 ns, N = 69), and the mean 10-to-90% risetime is 43.6 ns (S.D., 24.2 ns, N = 69). From modeling, we determine the properties of the leader step currents which produced two typical measured field derivatives, and we use one of these currents to calculate predicted leader step E and dE/dt as a function of source range and height, the results being in good agreement with our observations. The two modeled current waveforms had maximum rates of current rise-to-peak near 100 kA {micro}s{sup -1}, peak currents in the 5-7 kA range, current half-peak widths of about 300 ns, and charge transfers of {approx}3 mC. As part of the modeling, those currents were propagated upward at 1.5 x 10{sup 8} m s{sup -1}, with their amplitudes decaying exponentially with a decay height constant of 25 m.« less

  16. Trisomy 2q11.2-->q21.1 resulting from an unbalanced insertion in two generations.

    PubMed Central

    Glass, I A; Stormer, P; Oei, P T; Hacking, E; Cotter, P D

    1998-01-01

    In this communication, we describe two cases of proximal 2q trisomy (2q11.2--> q21.1) resulting from an interchromosomal insertion. The chromosomal origin of the insertion was confirmed by fluorescence in situ hybridisation. An unbalanced karyotype, 46,XX,der(8) ,ins(8;2) (p21.3; q21.1q11.2), was found in the proband and her mother, who both have mild mental retardation, short stature, dysmorphic features, insulin dependent diabetes mellitus, and a psychotic illness. This family is a rare example of direct transmission of a partial autosomal trisomy. Images PMID:9598728

  17. Analytical close-form solutions to the elastic fields of solids with dislocations and surface stress

    NASA Astrophysics Data System (ADS)

    Ye, Wei; Paliwal, Bhasker; Ougazzaden, Abdallah; Cherkaoui, Mohammed

    2013-07-01

    The concept of eigenstrain is adopted to derive a general analytical framework to solve the elastic field for 3D anisotropic solids with general defects by considering the surface stress. The formulation shows the elastic constants and geometrical features of the surface play an important role in determining the elastic fields of the solid. As an application, the analytical close-form solutions to the stress fields of an infinite isotropic circular nanowire are obtained. The stress fields are compared with the classical solutions and those of complex variable method. The stress fields from this work demonstrate the impact from the surface stress when the size of the nanowire shrinks but becomes negligible in macroscopic scale. Compared with the power series solutions of complex variable method, the analytical solutions in this work provide a better platform and they are more flexible in various applications. More importantly, the proposed analytical framework profoundly improves the studies of general 3D anisotropic materials with surface effects.

  18. Plasma diagnostics of low pressure high power impulse magnetron sputtering assisted by electron cyclotron wave resonance plasma

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Stranak, Vitezslav; University of South Bohemia, Institute of Physics and Biophysics, Branisovska 31, 370 05 Ceske Budejovice; Herrendorf, Ann-Pierra

    2012-11-01

    This paper reports on an investigation of the hybrid pulsed sputtering source based on the combination of electron cyclotron wave resonance (ECWR) inductively coupled plasma and high power impulse magnetron sputtering (HiPIMS) of a Ti target. The plasma source, operated in an Ar atmosphere at a very low pressure of 0.03 Pa, provides plasma where the major fraction of sputtered particles is ionized. It was found that ECWR assistance increases the electron temperature during the HiPIMS pulse. The discharge current and electron density can achieve their stable maximum 10 {mu}s after the onset of the HiPIMS pulse. Further, a highmore » concentration of double charged Ti{sup ++} with energies of up to 160 eV was detected. All of these facts were verified experimentally by time-resolved emission spectroscopy, retarding field analyzer measurement, Langmuir probe, and energy-resolved mass spectrometry.« less

  19. Characteristic of Nano-Cu Film Prepared by Energy Filtrating Magnetron Sputtering Technique and Its Optical Property

    NASA Astrophysics Data System (ADS)

    Wang, Zhaoyong; Hu, Xing; Yao, Ning

    2015-03-01

    At the optimized deposition parameters, Cu film was deposited by the direct current magnetron sputtering (DMS) technique and the energy filtrating magnetron sputtering (EFMS) technique. The nano-structure was charactered by x-ray diffraction. The surface morphology of the film was observed by atomic force microscopy. The optical properties of the film were measured by spectroscopic ellipsometry. The refractive index, extinction coefficient and the thickness of the film were obtained by the fitted spectroscopic ellipsometry data using the Drude-Lorentz oscillator optical model. Results suggested that a Cu film with different properties was fabricated by the EFMS technique. The film containing smaller particles is denser and the surface is smoother. The average transmission coefficient, the refractive index and the extinction coefficients are higher than those of the Cu film deposited by the DMS technique. The average transmission coefficient (400-800 nm) is more than three times higher. The refractive index and extinction coefficient (at 550 nm) are more than 36% and 14% higher, respectively.

  20. Use of unbalanced laminates as a screening method for microcracking

    NASA Technical Reports Server (NTRS)

    Papadopoulos, Demetrios S.; Bowles, Kenneth J.

    1990-01-01

    State-of-the-art, high temperature polyimide matrix composites, reinforced with continuous graphite fibers are known to be susceptible to intraply cracking when thermally cycled over their useful service temperature range. It is believed that the transply cracking, in part, results from residual stresses caused by differences in coefficients of thermal expansion (CTE) between the polymer matrix and the reinforcement. Thermal cycling tests to investigate this phenomenon involve expensive time and energy consuming programs which are not economically feasible for use as a part of a materials screening process. As an alternative to thermal cycling studies, a study of unbalanced crossply graphite fiber reinforcement composites was conducted to assess the effect of the composite ply layup and surface condition on the residual stresses that remain after the processing of these materials. The residual stresses were assessed by measuring the radii of curvature of the types of laminates that were studied. The temperature at which stress-free conditions existed were determined and a dye penetrant method was used to observe surface damage resulting from excessive residual stress buildup. These results are compared with some published results of thermal cycling tests that were previously conducted on balanced polyimide composites.

  1. Studies on Magnetron Sputtered ZnO-Ag Films: Adhesion Activity of S. aureus

    NASA Astrophysics Data System (ADS)

    Geetha, S. R.; Dhivya, P.; Raj, P. Deepak; Sridharan, M.; Princy, S. Adline

    Zinc oxide (ZnO) thin films have been deposited onto thoroughly cleaned stainless steel (AISI SS 304) substrates by reactive direct current (dc) magnetron sputtering and the films were doped with silver (Ag). The prepared thin films were analyzed using X-ray diffraction (XRD), field emission-scanning electron microscopy (FE-SEM) to investigate the structural and morphological properties. The thickness values of the films were in the range of 194 to 256nm. XRD results revealed that the films were crystalline with preferred (002) orientation. Grain size values of pure ZnO films were found to be 19.82-23.72nm. On introducing Ag into ZnO film, the micro-structural properties varied. Adhesion test was carried out with Staphylococcus aureus (S. aureus) in order to know the adherence property of the deposited films. Colony formation units (CFU) were counted manually and bacterial adhesion inhibition (BAI) was calculated. We observed a decrease in the CFU on doping Ag in the ZnO films. BAI of the film deposited at - 100 V substrate bias was found to be increased on Ag doping from 69 to 88%.

  2. CLOSED-FIELD CORONAL HEATING DRIVEN BY WAVE TURBULENCE

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Downs, Cooper; Lionello, Roberto; Mikić, Zoran

    To simulate the energy balance of coronal plasmas on macroscopic scales, we often require the specification of the coronal heating mechanism in some functional form. To go beyond empirical formulations and to build a more physically motivated heating function, we investigate the wave-turbulence-driven (WTD) phenomenology for the heating of closed coronal loops. Our implementation is designed to capture the large-scale propagation, reflection, and dissipation of wave turbulence along a loop. The parameter space of this model is explored by solving the coupled WTD and hydrodynamic evolution in 1D for an idealized loop. The relevance to a range of solar conditionsmore » is also established by computing solutions for over one hundred loops extracted from a realistic 3D coronal field. Due to the implicit dependence of the WTD heating model on loop geometry and plasma properties along the loop and at the footpoints, we find that this model can significantly reduce the number of free parameters when compared to traditional empirical heating models, and still robustly describe a broad range of quiet-Sun and active region conditions. The importance of the self-reflection term in producing relatively short heating scale heights and thermal nonequilibrium cycles is also discussed.« less

  3. Closed-field Coronal Heating Driven by Wave Turbulence

    NASA Astrophysics Data System (ADS)

    Downs, Cooper; Lionello, Roberto; Mikić, Zoran; Linker, Jon A.; Velli, Marco

    2016-12-01

    To simulate the energy balance of coronal plasmas on macroscopic scales, we often require the specification of the coronal heating mechanism in some functional form. To go beyond empirical formulations and to build a more physically motivated heating function, we investigate the wave-turbulence-driven (WTD) phenomenology for the heating of closed coronal loops. Our implementation is designed to capture the large-scale propagation, reflection, and dissipation of wave turbulence along a loop. The parameter space of this model is explored by solving the coupled WTD and hydrodynamic evolution in 1D for an idealized loop. The relevance to a range of solar conditions is also established by computing solutions for over one hundred loops extracted from a realistic 3D coronal field. Due to the implicit dependence of the WTD heating model on loop geometry and plasma properties along the loop and at the footpoints, we find that this model can significantly reduce the number of free parameters when compared to traditional empirical heating models, and still robustly describe a broad range of quiet-Sun and active region conditions. The importance of the self-reflection term in producing relatively short heating scale heights and thermal nonequilibrium cycles is also discussed.

  4. Fabrication and characterization of He-charged ODS-FeCrNi films deposited by a radio-frequency plasma magnetron sputtering technique

    NASA Astrophysics Data System (ADS)

    Song, Liang; Wang, Xianping; Wang, Le; Zhang, Ying; Liu, Wang; Jiang, Weibing; Zhang, Tao; Fang, Qianfeng; Liu, Changsong

    2017-04-01

    He-charged oxide dispersion strengthened (ODS) FeCrNi films were prepared by a radio-frequency (RF) plasma magnetron sputtering method in a He and Ar mixed atmosphere at 150 °C. As a comparison, He-charged FeCrNi films were also fabricated at the same conditions through direct current (DC) plasma magnetron sputtering. The doping of He atoms and Y2O3 in the FeCrNi films was realized by the high backscattered rate of He ions and Y2O3/FeCrNi composite target sputtering method, respectively. Inductive coupled plasma (ICP) and x-ray photoelectron spectroscopy (XPS) analysis confirmed the existence of Y2O3 in FeCrNi films, and Y2O3 content hardly changed with sputtering He/Ar ratio. Cross-sectional scanning electron microscopy (SEM) shows that the FeCrNi films were composed of dense columnar nanocrystallines and the thickness of the films was obviously dependent on He/Ar ratio. Nanoindentation measurements revealed that the FeCrNi films fabricated through DC/RF plasma magnetron sputtering methods exhibited similar hardness values at each He/Ar ratio, while the dispersion of Y2O3 apparently increased the hardness of the films. Elastic recoil detection (ERD) showed that DC/RF magnetron sputtered FeCrNi films contained similar He amounts (˜17 at.%). Compared with the minimal change of He level with depth in DC-sputtered films, the He amount decreases gradually in depth in the RF-sputtered films. The Y2O3-doped FeCrNi films were shown to exhibit much smaller amounts of He owing to the lower backscattering possibility of Y2O3 and the inhibition effect of nano-sized Y2O3 particles on the He element.

  5. Two-phase nc-TiN/a-(C,CN{sub x}) nanocomposite films: A HRTEM and MC simulation study

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Guo, J.; Lu, Y. H.; Hu, X. J.

    2013-06-18

    The grain growth in two-phase nanocomposite Ti-C{sub x}-N{sub y} thin films grown by reactive close-field unbalanced magnetron sputtering in an Ar-N{sub 2} gas mixture with microstructures comprising of nanocrystalline (nc-) Ti(N,C) phase surrounded by amorphous (a-) (C,CN{sub x}) phase was investigated by a combination of high-resolution transmission electron microscopy (HRTEM) and Monte Carlo (MC) simulations. The HRTEM results revealed that amorphous-free solid solution Ti(C,N) thin films exhibited polycrystallites with different sizes, orientations and irregular shapes. The grain size varied in the range between several nanometers and several decade nanometers. Further increase of C content (up to {approx}19 at.% C) mademore » the amorphous phase wet nanocrystallites, which strongly hindered the growth of nanocrystallites. As a result, more regular Ti(C,N) nanocrystallites with an average size of {approx}5 nm were found to be separated by {approx}0.5-nm amorphous phases. When C content was further increased (up to {approx}48 at.% in this study), thicker amorphous matrices were produced and followed by the formation of smaller sized grains with lognormal distribution. Our MC analysis indicated that with increasing amorphous volume fraction (i.e. increasing C content), the transformation from nc/nc grain boundary (GB)-curvature-driven growth to a/nc GB-curvature-driven growth is directly responsible for the observed grain growth from great inhomogeneity to homogeneity process.« less

  6. Tribological properties, corrosion resistance and biocompatibility of magnetron sputtered titanium-amorphous carbon coatings

    NASA Astrophysics Data System (ADS)

    Dhandapani, Vishnu Shankar; Subbiah, Ramesh; Thangavel, Elangovan; Arumugam, Madhankumar; Park, Kwideok; Gasem, Zuhair M.; Veeraragavan, Veeravazhuthi; Kim, Dae-Eun

    2016-05-01

    Amorphous carbon incorporated with titanium (a-C:Ti) was coated on 316L stainless steel (SS) by magnetron sputtering technique to attain superior tribological properties, corrosion resistance and biocompatibility. The morphology, topography and functional groups of the nanostructured a-C:Ti coatings in various concentrations were analyzed using atomic force microscopy (AFM), Raman, X-Ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Raman and XPS analyses confirmed the increase in sp2 bonds with increasing titanium content in the a-C matrix. TEM analysis confirmed the composite nature of the coating and the presence of nanostructured TiC for Ti content of 2.33 at.%. This coating showed superior tribological properties compared to the other a-C:Ti coatings. Furthermore, electrochemical corrosion studies were performed against stimulated body fluid medium in which all the a-C:Ti coatings showed improved corrosion resistance than the pure a-C coating. Preosteoblasts proliferation and viability on the specimens were tested and the results showed that a-C:Ti coatings with relatively high Ti (3.77 at.%) content had better biocompatibility. Based on the results of this work, highly durable coatings with good biocompatibility could be achieved by incorporation of optimum amount of Ti in a-C coatings deposited on SS by magnetron sputtering technique.

  7. Algan/Gan Hemt By Magnetron Sputtering System

    NASA Astrophysics Data System (ADS)

    Garcia Perez, Roman

    In this thesis, the growth of the semiconductor materials AlGaN and GaN is achieved by magnetron sputtering for the fabrication of High Electron Mobility Transistors (HEMTs). The study of the deposited nitrides is conducted by spectroscopy, diffraction, and submicron scale microscope methods. The preparation of the materials is performed using different parameters in terms of power, pressure, temperature, gas, and time. Silicon (Si) and Sapphire (Al2O3) wafers are used as substrates. The chemical composition and surface topography of the samples are analyzed to calculate the materials atomic percentages and to observe the devices surface. The instruments used for the semiconductors characterization are X-ray Photoelectron Spectroscopy (XPS), X-ray Diffraction (XRD), Scanning Electron Microscopy (SEM), and Atomic Force Microscope (AFM). The project focused its attention on the reduction of impurities during the deposition, the controlled thicknesses of the thin-films, the atomic configuration of the alloy AlxGa1-xN, and the uniformity of the surfaces.

  8. Electrical Conducting and Mechanism of Oxygen-Deficient Tin Oxide Films Deposited by RF Magnetron Sputtering at Various O2/Ar Ratios

    NASA Astrophysics Data System (ADS)

    Wang, Qi; Wang, Chengbiao; Lv, Changchun; Wang, Yang; Peng, Zhijian; Fu, Xiuli

    Oxygen-deficient tin oxide thin films were prepared by radiofrequency magnetron sputtering with a sintered non-stoichiometric tin oxide ceramic target under an atmosphere of various ratios of O2/Ar from pure Ar to 1:1. X-ray diffraction analysis showed that the thin films were polycrystalline with relatively strong (1 1 0), (1 0 1) and (2 1 1) diffraction peaks. Scanning electron microscopy observation revealed that the thin films prepared at different O2/Ar ratios were all of relatively dense and homogeneous structure. With increasing O2/Ar ratio, the grain size of the films decreased slightly, and their chemical composition became close to the stoichiometric SnO2; but the deposition rate as well as film thickness increased first and then decreased sharply. It was revealed that the main defect in obtained films was oxygen vacancy (VO), and as the O2/Ar ratio increased, the concentration of VO fell down monotonously, which would lead to an increased electrical resistivity.

  9. Noise analysis in numerical modeling of crossed fields microwave tubes

    NASA Astrophysics Data System (ADS)

    BłaŻejewicz, Mariusz; Woźniak, Martyna; Szkop, Emil; RóŻycki, Andrzej; Rychlewski, Michał; Baczewski, Dariusz; Laskowski, Dariusz

    2018-04-01

    One of the most important parameters that characterize microwave tubes with crossed fields, both amplifiers (CFA), and generating tubes like magnetrons is the noise level. This type of tubes are characterized by relatively high noise levels, which is the main factor limiting their current use in radar transmitters. The main source of noise in microwave tubes of this type is the dispersion of the energy of electrons that are in phase with the spatial wave of the electromagnetic field propagating in the delay line (in case of an amplitron) or in the resonant structure (in case of a magnetron).The results of the research presented in the article concern the technique of determination of Signal to Noise Ratio (SNR) based on the analysis of results obtained during the numerical simulations of the effect of electric charge on a high frequency electromagnetic field. Signal to noise ratio was determined by analysing in-phase and quadrature data recorded in the high frequency simulation. In order to assess the accuracy of the method under investigation, the results from the noise analysis obtained from numerical calculations were compared with the results obtained from real tube measurements performed by a spectrum analyser. On the basis of the research, it appears that performing analysis of noise generated in the interaction area may be useful for preliminary evaluation of the tube at the design stage.

  10. Characterization on RF magnetron sputtered niobium pentoxide thin films

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Usha, N.; Sivakumar, R., E-mail: krsivakumar1979@yahoo.com; Sanjeeviraja, C.

    2014-10-15

    Niobium pentoxide (Nb{sub 2}O{sub 5}) thin films with amorphous nature were deposited on microscopic glass substrates at 100°C by rf magnetron sputtering technique. The effect of rf power on the structural, morphological, optical, and vibrational properties of Nb{sub 2}O{sub 5} films have been investigated. Optical study shows the maximum average transmittance of about 87% and the optical energy band gap (indirect allowed) changes between 3.70 eV and 3.47 eV. AFM result indicates the smooth surface nature of the samples. Photoluminescence measurement showed the better optical quality of the deposited films. Raman spectra show the LO-TO splitting of Nb-O stretching ofmore » Nb{sub 2}O{sub 5} films.« less

  11. Unbalanced Activation of Glutathione Metabolic Pathways Suggests Potential Involvement in Plant Defense against the Gall Midge Mayetiola destructor in Wheat

    PubMed Central

    Liu, Xuming; Zhang, Shize; Whitworth, R. Jeff; Stuart, Jeffrey J.; Chen, Ming-Shun

    2015-01-01

    Glutathione, γ-glutamylcysteinylglycine, exists abundantly in nearly all organisms. Glutathione participates in various physiological processes involved in redox reactions by serving as an electron donor/acceptor. We found that the abundance of total glutathione increased up to 60% in resistant wheat plants within 72 hours following attack by the gall midge Mayetiola destructor, the Hessian fly. The increase in total glutathione abundance, however, is coupled with an unbalanced activation of glutathione metabolic pathways. The activity and transcript abundance of glutathione peroxidases, which convert reduced glutathione (GSH) to oxidized glutathione (GSSG), increased in infested resistant plants. However, the enzymatic activity and transcript abundance of glutathione reductases, which convert GSSG back to GSH, did not change. This unbalanced regulation of the glutathione oxidation/reduction cycle indicates the existence of an alternative pathway to regenerate GSH from GSSG to maintain a stable GSSG/GSH ratio. Our data suggest the possibility that GSSG is transported from cytosol to apoplast to serve as an oxidant for class III peroxidases to generate reactive oxygen species for plant defense against Hessian fly larvae. Our results provide a foundation for elucidating the molecular processes involved in glutathione-mediated plant resistance to Hessian fly and potentially other pests as well. PMID:25627558

  12. Enabling Unbalanced Fermentations by Using Engineered Electrode-Interfaced Bacteria

    PubMed Central

    Flynn, Jeffrey M.; Ross, Daniel E.; Hunt, Kristopher A.; Bond, Daniel R.; Gralnick, Jeffrey A.

    2010-01-01

    Cellular metabolism is a series of tightly linked oxidations and reductions that must be balanced. Recycling of intracellular electron carriers during fermentation often requires substrate conversion to undesired products, while respiration demands constant addition of electron acceptors. The use of electrode-based electron acceptors to balance biotransformations may overcome these constraints. To test this hypothesis, the metal-reducing bacterium Shewanella oneidensis was engineered to stoichiometrically convert glycerol into ethanol, a biotransformation that will not occur unless two electrons are removed via an external reaction, such as electrode reduction. Multiple modules were combined into a single plasmid to alter S. oneidensis metabolism: a glycerol module, consisting of glpF, glpK, glpD, and tpiA from Escherichia coli, and an ethanol module containing pdc and adh from Zymomonas mobilis. A further increase in product yields was accomplished through knockout of pta, encoding phosphate acetyltransferase, shifting flux toward ethanol and away from acetate production. In this first-generation demonstration, conversion of glycerol to ethanol required the presence of an electrode to balance the reaction, and electrode-linked rates were on par with volumetric conversion rates observed in engineered E. coli. Linking microbial biocatalysis to current production can eliminate redox constraints by shifting other unbalanced reactions to yield pure products and serve as a new platform for next-generation bioproduction strategies. PMID:21060736

  13. Full System Model of Magnetron Sputter Chamber - Proof-of-Principle Study

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Walton, C; Gilmer, G; Zepeda-Ruiz, L

    2007-05-04

    The lack of detailed knowledge of internal process conditions remains a key challenge in magnetron sputtering, both for chamber design and for process development. Fundamental information such as the pressure and temperature distribution of the sputter gas, and the energies and arrival angles of the sputtered atoms and other energetic species is often missing, or is only estimated from general formulas. However, open-source or low-cost tools are available for modeling most steps of the sputter process, which can give more accurate and complete data than textbook estimates, using only desktop computations. To get a better understanding of magnetron sputtering, wemore » have collected existing models for the 5 major process steps: the input and distribution of the neutral background gas using Direct Simulation Monte Carlo (DSMC), dynamics of the plasma using Particle In Cell-Monte Carlo Collision (PIC-MCC), impact of ions on the target using molecular dynamics (MD), transport of sputtered atoms to the substrate using DSMC, and growth of the film using hybrid Kinetic Monte Carlo (KMC) and MD methods. Models have been tested against experimental measurements. For example, gas rarefaction as observed by Rossnagel and others has been reproduced, and it is associated with a local pressure increase of {approx}50% which may strongly influence film properties such as stress. Results on energies and arrival angles of sputtered atoms and reflected gas neutrals are applied to the Kinetic Monte Carlo simulation of film growth. Model results and applications to growth of dense Cu and Be films are presented.« less

  14. The magnetic field in the very close neighborhood of Mars according to data from the Mars 2 and Mars 3 spacecraft

    NASA Technical Reports Server (NTRS)

    Dolginov, S. S.; Yeroshenko, Y. G.; Zhuzgov, L. N.

    1972-01-01

    The magnetic field in the close proximity of planet Mars according to data from Mars 2 and Mars 3 spacecraft is discussed. The magnetometers on the spacecraft detected a field whose intensity near the orbital periapses was 7 to 10 times higher than the interplanetary field at the distance of the Martian orbit. The nature of the observed field is described.

  15. Unbalanced translocation 6p/16q (partial monosomy 6p and trisomy 16q): prenatal diagnosis and cytogenetics.

    PubMed

    Puhl, Alexander G; Zelazny, Julia; Galetzka, Danuta; Skala, Christine; Frey-Mahn, Gabriele; Wellek, Brigitte; Koelbl, Heinz

    2010-06-01

    Unbalanced translocation 6p/16q in one fetus is a very rare event and the prenatal sonographic findings have never been published before. We will give a short overview of the literature along with a case report focussing on prenatal ultrasound features and molecular cytogenetic analysis. A 21-year-old primigravid woman presented with a singleton pregnancy at 19 weeks' gestation. The fetus revealed a mild hydrocephalus, a ventricular septal defect (VSD), a Dandy-Walker malformation as well as an intrauterine growth retardation (IUGR) and limb anomalities. MLPA analysis from amniotic fluid cells showed an unbalanced translocation from the subtelomeric region of chromosome 6p to the subtelomeric region of chromosome 16q. Karyotype of the fetus was 46, XX.ishder(6)t(6;16)(p2?5;q?13)(pVYS246A+, pVYS228B-, pVYS229A+). Despite the karyotype the mother decided not to interrupt pregnancy. The fetus died in utero within the 39th week of gestation and was delivered vaginally after labour induction, with a birth weight of 1815g. Prenatal FISH and MLPA studies can be very important to help outline the chromosomal area of deletion and duplication and the sonographic findings forebode the cytogenetic region of interest. Subsequent to the processing of the case, a complete Medline search was conducted to review previous cases with similar genetic alterations. Copyright 2010 Elsevier Ireland Ltd. All rights reserved.

  16. Antibacterial properties of nano-silver coated PEEK prepared through magnetron sputtering.

    PubMed

    Liu, Xiuju; Gan, Kang; Liu, Hong; Song, Xiaoqing; Chen, Tianjie; Liu, Chenchen

    2017-09-01

    We aimed to investigate the cytotoxicity and antibacterial properties of nano-silver-coated polyetheretherketone (PEEK) produced through magnetron sputtering and provide a theoretical basis for its use in clinical applications. The surfaces of PEEKs were coated with nano-silver at varying thicknesses (3, 6, 9, and 12nm) through magnetron sputtering technology. The resulting coated PEEK samples were classified into the following groups according to the thickness of the nano-silver coating: PEEK-3 (3nm), PEEK-6 (6nm), PEEK-9 (9nm), PEEK-12 (12nm), and PEEK control group. The surface microstructure and composition of each sample were observed by scanning electron microscopy (SEM), atomic force microscopy (AFM), and energy dispersive spectrum (EDS) analysis. The water contact angle of each sample was then measured by contact angle meters. A cell counting kit (CCK-8) was used to analyze the cytotoxicity of the mouse fibroblast cells (L929) in the coated groups (n=5) and group test samples (n=6), negative control (polyethylene, PE) (n=6), and positive control group (phenol) (n=6). The antibacterial properties of the samples were tested by co-culturing Streptococcus mutans and Straphylococcus aureus. The bacteria that adhered to the surface of samples were observed by SEM. The antibacterial adhesion ability of each sample was then evaluated. SEM and AFM analysis results showed that the surfaces of control group samples were smooth but compact. Homogeneous silver nano-particles (AgNPs) and nano-silver coating were uniformly distributed on the surface of the coated group samples. Compared with the control samples, the nano-silver coated samples had a significant increase in surface roughness (P<0.05) as the thickness of their nano-silver coating increased. EDS analysis showed that not only C and O but also Ag were present on the surface of the coated samples. Moreover, the water contact angle of modified samples significantly increased after nano-silver coating modification

  17. Overview of recent studies and design changes for the FNAL magnetron ion source

    NASA Astrophysics Data System (ADS)

    Bollinger, D. S.; Sosa, A.

    2017-08-01

    This paper presents several studies and design changes that will eventually be implemented to the Fermi National Accelerator Laboratory (FNAL) magnetron ion source. The topics include tungsten cathode insert, solenoid gas valves, current controlled arc pulser, cesium boiler redesign, gas mixtures of hydrogen and nitrogen, and duty factor reduction. The studies were performed on the FNAL test stand described in [1], with the aim to improve source lifetime, stability, and reducing the amount of tuning needed.

  18. Definition and design of an experiment to test raster scanning with rotating unbalanced-mass devices on gimbaled payloads

    NASA Technical Reports Server (NTRS)

    Lightsey, W. D.; Alhorn, D. C.; Polites, M. E.

    1992-01-01

    An experiment designed to test the feasibility of using rotating unbalanced-mass (RUM) devices for line and raster scanning gimbaled payloads, while expending very little power is described. The experiment is configured for ground-based testing, but the scan concept is applicable to ground-based, balloon-borne, and space-based payloads, as well as free-flying spacecraft. The servos used in scanning are defined; the electronic hardware is specified; and a computer simulation model of the system is described. Simulation results are presented that predict system performance and verify the servo designs.

  19. Observations of the Ion Signatures of Double Merging and the Formation of Newly Closed Field Lines

    NASA Technical Reports Server (NTRS)

    Chandler, Michael O.; Avanov, Levon A.; Craven, Paul D.

    2007-01-01

    Observations from the Polar spacecraft, taken during a period of northward interplanetary magnetic field (IMF) show magnetosheath ions within the magnetosphere with velocity distributions resulting from multiple merging sites along the same field line. The observations from the TIDE instrument show two separate ion energy-time dispersions that are attributed to two widely separated (-20Re) merging sites. Estimates of the initial merging times show that they occurred nearly simultaneously (within 5 minutes.) Along with these populations, cold, ionospheric ions were observed counterstreaming along the field lines. The presence of such ions is evidence that these field lines are connected to the ionosphere on both ends. These results are consistent with the hypothesis that double merging can produce closed field lines populated by solar wind plasma. While the merging sites cannot be unambiguously located, the observations and analyses favor one site poleward of the northern cusp and a second site at low latitudes.

  20. Reactive magnetron sputtering of N-doped carbon thin films on quartz glass for transmission photocathode applications

    NASA Astrophysics Data System (ADS)

    Balalykin, N. I.; Huran, J.; Nozdrin, M. A.; Feshchenko, A. A.; Kobzev, A. P.; Sasinková, V.; Boháček, P.; Arbet, J.

    2018-03-01

    N-doped carbon thin films were deposited on a silicon substrate and quartz glass by RF reactive magnetron sputtering using a carbon target and an Ar+N2 gas mixture. During the magnetron sputtering, the substrate holder temperatures was kept at 800 °C. The carbon film thickness on the silicon substrate was about 70 nm, while on the quartz glass it was in the range 15 nm – 60 nm. The elemental concentration in the films was determined by RBS and ERD. Raman spectroscopy was used to evaluate the intensity ratios I D/I G of the D and G peaks of the carbon films. The transmission photocathodes prepared were placed in the hollow-cathode assembly of a Pierce-structure DC gun to produce photoelectrons. The quantum efficiency (QE) was calculated from the laser energy and cathode charge measured. The properties of the transmission photocathodes based on semitransparent N-doped carbon thin films on quartz glass and their potential for application in DC gun technology are discussed.

  1. Boron ion beam generation utilizing lanthanum hexaboride cathodes: Comparison of vacuum arc and planar magnetron glow

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Nikolaev, A. G.; Vizir, A. V.; Yushkov, G. Yu., E-mail: gyushkov@mail.ru

    Boron ion beams are widely used for semiconductor ion implantation and for surface modification for improving the operating parameters and increasing the lifetime of machine parts and tools. For the latter application, the purity requirements of boron ion beams are not as stringent as for semiconductor technology, and a composite cathode of lanthanum hexaboride may be suitable for the production of boron ions. We have explored the use of two different approaches to boron plasma production: vacuum arc and planar high power impulse magnetron in self-sputtering mode. For the arc discharge, the boron plasma is generated at cathode spots, whereasmore » for the magnetron discharge, the main process is sputtering of cathode material. We present here the results of comparative test experiments for both kinds of discharge, aimed at determining the optimal discharge parameters for maximum yield of boron ions. For both discharges, the extracted ion beam current reaches hundreds of milliamps and the fraction of boron ions in the total extracted ion beam is as high as 80%.« less

  2. A new method of nanocrystalline nickel powder formation by magnetron sputtering on the water-soluble substrates

    NASA Astrophysics Data System (ADS)

    Tučkutė, S.; Urbonavičius, M.; Lelis, M.; Maiorov, M.; Díaz Ordaz, J. R.; Milčius, D.

    2018-01-01

    Due to the accurate and relatively easy control magnetron sputtering is an attractive technique for the synthesis of metallic particles. This work describes a new method of nickel powder production by depositing nickel on the surface of sodium chloride particles which were used as the template and are soluble in water. Ni powder with flake-like structure was obtained after washing Ni coated salt particles in ultrasonic cleaner. Salt particles and nickel powder were characterized using scanning electron microscope (SEM), energy-dispersive x-ray spectrometer, XRD and X-ray photoelectron spectroscopy (XPS) techniques. SEM images showed that thickness of the received Ni particles varied in the nanoscale and depended on the magnetron deposition time but did not depend on the size of salt particles. On the other hand initial size of the salt particles was successfully employed a measure to control lateral dimensions of Ni powder. XRD and XPS analysis results revealed that Ni particles had metallic core and oxidized shell which was a cause of the slightly deteriorated magnetic properties.

  3. Optical fiber magnetic field sensors with TbDyFe magnetostrictive thin films as sensing materials.

    PubMed

    Yang, Minghong; Dai, Jixiang; Zhou, Ciming; Jiang, Desheng

    2009-11-09

    Different from usually-used bulk magnetostrictive materials, magnetostrictive TbDyFe thin films were firstly proposed as sensing materials for fiber-optic magnetic field sensing characterization. By magnetron sputtering process, TbDyFe thin films were deposited on etched side circle of a fiber Bragg Grating (FBG) as sensing element. There exists more than 45pm change of FBG wavelength when magnet field increase up to 50 mT. The response to magnetic field is reversible, and could be applicable for magnetic and current sensing.

  4. Characterization of sp3 bond content of carbon films deposited by high power gas injection magnetron sputtering method by UV and VIS Raman spectroscopy.

    PubMed

    Zdunek, Krzysztof; Chodun, Rafał; Wicher, Bartosz; Nowakowska-Langier, Katarzyna; Okrasa, Sebastian

    2018-04-05

    This paper presents the results of investigations of carbon films deposited by a modified version of the magnetron sputtering method - HiPGIMS (High Power Gas Injection Magnetron Sputtering). In this experiment, the magnetron system with inversely polarized electrodes (sputtered cathode at ground potential and positively biased, spatially separated anode) was used. This arrangement allowed us to conduct the experiment using voltages ranging from 1 to 2kV and a power supply system equipped with 25/50μF capacitor battery. Carbon films were investigated by VIS/UV Raman spectroscopy. Sp 3 /sp 2 bonding ratio was evaluated basing the elementary components of registered spectra. Our investigation showed that sp 3 bond content increases with discharge power but up to specific value only. In extreme conditions of generating plasma impulses, we detected a reversed relation of the sp 3 /sp 2 ratio. In our opinion, a energy of plasma pulse favors nucleation of a sp 3 phase because of a relatively higher ionization state but in extreme cases the influence of energy is reversed. Copyright © 2018 Elsevier B.V. All rights reserved.

  5. System having unmodulated flux locked loop for measuring magnetic fields

    DOEpatents

    Ganther, Jr., Kenneth R.; Snapp, Lowell D [Blue Springs, MO

    2006-08-15

    A system (10) for measuring magnetic fields, wherein the system (10) comprises an unmodulated or direct-feedback flux locked loop (12) connected by first and second unbalanced RF coaxial transmission lines (16a, 16b) to a superconducting quantum interference device (14). The FLL (12) operates for the most part in a room-temperature or non-cryogenic environment, while the SQUID (14) operates in a cryogenic environment, with the first and second lines (16a, 16b) extending between these two operating environments.

  6. Window-closing safety system

    DOEpatents

    McEwan, Thomas E.

    1997-01-01

    A safety device includes a wire loop embedded in the glass of a passenger car window and routed near the closing leading-edge of the window. The wire loop carries microwave pulses around the loop to and from a transceiver with separate output and input ports. An evanescent field only and inch or two in radius is created along the wire loop by the pulses. Just about any object coming within the evanescent field will dramatically reduce the energy of the microwave pulses received back by the transceiver. Such a loss in energy is interpreted as a closing area blockage, and electrical interlocks are provided to halt or reverse a power window motor that is actively trying to close the window.

  7. Window-closing safety system

    DOEpatents

    McEwan, T.E.

    1997-08-26

    A safety device includes a wire loop embedded in the glass of a passenger car window and routed near the closing leading-edge of the window. The wire loop carries microwave pulses around the loop to and from a transceiver with separate output and input ports. An evanescent field only an inch or two in radius is created along the wire loop by the pulses. Just about any object coming within the evanescent field will dramatically reduce the energy of the microwave pulses received back by the transceiver. Such a loss in energy is interpreted as a closing area blockage, and electrical interlocks are provided to halt or reverse a power window motor that is actively trying to close the window. 5 figs.

  8. Simplified Estimation and Testing in Unbalanced Repeated Measures Designs.

    PubMed

    Spiess, Martin; Jordan, Pascal; Wendt, Mike

    2018-05-07

    In this paper we propose a simple estimator for unbalanced repeated measures design models where each unit is observed at least once in each cell of the experimental design. The estimator does not require a model of the error covariance structure. Thus, circularity of the error covariance matrix and estimation of correlation parameters and variances are not necessary. Together with a weak assumption about the reason for the varying number of observations, the proposed estimator and its variance estimator are unbiased. As an alternative to confidence intervals based on the normality assumption, a bias-corrected and accelerated bootstrap technique is considered. We also propose the naive percentile bootstrap for Wald-type tests where the standard Wald test may break down when the number of observations is small relative to the number of parameters to be estimated. In a simulation study we illustrate the properties of the estimator and the bootstrap techniques to calculate confidence intervals and conduct hypothesis tests in small and large samples under normality and non-normality of the errors. The results imply that the simple estimator is only slightly less efficient than an estimator that correctly assumes a block structure of the error correlation matrix, a special case of which is an equi-correlation matrix. Application of the estimator and the bootstrap technique is illustrated using data from a task switch experiment based on an experimental within design with 32 cells and 33 participants.

  9. Nanostructured titanium-silver coatings with good antibacterial activity and cytocompatibility fabricated by one-step magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Bai, Long; Hang, Ruiqiang; Gao, Ang; Zhang, Xiangyu; Huang, Xiaobo; Wang, Yueyue; Tang, Bin; Zhao, Lingzhou; Chu, Paul K.

    2015-11-01

    Bacterial infection and loosing are serious complications for biomedical implants in the orthopedic, dental, and other biomedical fields and the ideal implants should combine good antibacterial ability and bioactivity. In this study, nanostructured titanium-silver (Ti-Ag) coatings with different Ag contents (1.2 to 21.6 at%) are prepared on Ti substrates by magnetron sputtering. As the Ag concentration is increased, the coatings change from having dense columnar crystals to sparse ones and eventually no columnar structure. The Ti-Ag coatings can effectively kill Staphylococcus aureus during the first few days and remain moderately antibacterial after immersion for 75 days. Compared to pure Ti, the Ti-Ag coatings show good cytocompatibility as indicated by good osteoblast adhesion, proliferation, intracellular total protein synthesis, and alkaline phosphatase (ALP) activity. In addition, cell spreading, collagen secretion, and extracellular matrix mineralization are promoted on the coatings with the proper Ag contents due to the nanostructured morphological features. Our results indicate that favorable antibacterial activity and osseointegration ability can be simultaneously achieved by regulating the Ag contents in Ti-Ag coatings.

  10. Effects of post-deposition annealing ambient on band alignment of RF magnetron-sputtered Y2O3 film on gallium nitride

    PubMed Central

    2013-01-01

    The effects of different post-deposition annealing ambients (oxygen, argon, forming gas (95% N2 + 5% H2), and nitrogen) on radio frequency magnetron-sputtered yttrium oxide (Y2O3) films on n-type gallium nitride (GaN) substrate were studied in this work. X-ray photoelectron spectroscopy was utilized to extract the bandgap of Y2O3 and interfacial layer as well as establishing the energy band alignment of Y2O3/interfacial layer/GaN structure. Three different structures of energy band alignment were obtained, and the change of band alignment influenced leakage current density-electrical breakdown field characteristics of the samples subjected to different post-deposition annealing ambients. Of these investigated samples, ability of the sample annealed in O2 ambient to withstand the highest electric breakdown field (approximately 6.6 MV/cm) at 10−6 A/cm2 was related to the largest conduction band offset of interfacial layer/GaN (3.77 eV) and barrier height (3.72 eV). PMID:23360596

  11. Control of Low-Field Hysteresis Loop Shift of Spin Valves

    NASA Astrophysics Data System (ADS)

    Chernyshova, T. A.; Milyaev, M. A.; Naumova, L. I.; Proglyado, V. V.; Maksimova, I. K.; Pavlova, A. Yu.; Blagodatkov, D. V.; Ustinov, V. V.

    2017-12-01

    Spin valves that comprise synthetic antiferromagnet as a component of pinned layer and an exchange-coupled ferromagnet/Ru/ferromagnet structure in the free layer have been prepared by magnetron sputtering. Microobjects have been formed from spin valves by optical and electron-beam lithography. It has been shown that the shift of the low-field magnetoresistance hysteresis loop decreases as the thicknes of the Ru spacer in the free layer of spin valve increases. The almost hysteresis-free odd-field dependences of the magnetoresistance were obtained for micron-sized samples; in this case, the sensitivity is 0.2%/Oe.

  12. Why Does Rebalancing Class-Unbalanced Data Improve AUC for Linear Discriminant Analysis?

    PubMed

    Xue, Jing-Hao; Hall, Peter

    2015-05-01

    Many established classifiers fail to identify the minority class when it is much smaller than the majority class. To tackle this problem, researchers often first rebalance the class sizes in the training dataset, through oversampling the minority class or undersampling the majority class, and then use the rebalanced data to train the classifiers. This leads to interesting empirical patterns. In particular, using the rebalanced training data can often improve the area under the receiver operating characteristic curve (AUC) for the original, unbalanced test data. The AUC is a widely-used quantitative measure of classification performance, but the property that it increases with rebalancing has, as yet, no theoretical explanation. In this note, using Gaussian-based linear discriminant analysis (LDA) as the classifier, we demonstrate that, at least for LDA, there is an intrinsic, positive relationship between the rebalancing of class sizes and the improvement of AUC. We show that the largest improvement of AUC is achieved, asymptotically, when the two classes are fully rebalanced to be of equal sizes.

  13. SPEEDY babies: A putative new behavioral syndrome of unbalanced motor-speech development

    PubMed Central

    Haapanen, Marja-Leena; Aro, Tuomo; Isotalo, Elina

    2008-01-01

    Even though difficulties in motor development in children with speech and language disorders are widely known, hardly any attention is paid to the association between atypically rapidly occurring unassisted walking and delayed speech development. The four children described here presented with a developmental behavioral triad: 1) atypically speedy motor development, 2) impaired expressive speech, and 3) tongue carriage dysfunction resulting in related misarticulations. Those characteristics might be phenotypically or genetically clustered. These children didn’t have impaired cognition, neurological or mental disease, defective sense organs, craniofacial dysmorphology or susceptibility to upper respiratory infections, particularly recurrent otitis media. Attention should be paid on discordant and unbalanced achievement of developmental milestones. Present children are termed SPEEDY babies, where SPEEDY refers to rapid independent walking, SPEE and DY to dyspractic or dysfunctional speech development and lingual dysfunction resulting in linguoalveolar misarticulations. SPEEDY babies require health care that recognizes and respects their motor skills and supports their needs for motor activities and on the other hand include treatment for impaired speech. The parents may need advice and support with these children. PMID:19337462

  14. THE INTERSTELLAR MAGNETIC FIELD CLOSE TO THE SUN. II

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Frisch, P. C.; Andersson, B-G; Berdyugin, A.

    2012-12-01

    The magnetic field in the local interstellar medium (ISM) provides a key indicator of the galactic environment of the Sun and influences the shape of the heliosphere. We have studied the interstellar magnetic field (ISMF) in the solar vicinity using polarized starlight for stars within 40 pc of the Sun and 90 Degree-Sign of the heliosphere nose. In Frisch et al. (Paper I), we developed a method for determining the local ISMF direction by finding the best match to a group of interstellar polarization position angles obtained toward nearby stars, based on the assumption that the polarization is parallel tomore » the ISMF. In this paper, we extend the analysis by utilizing weighted fits to the position angles and by including new observations acquired for this study. We find that the local ISMF is pointed toward the galactic coordinates l, b =47 Degree-Sign {+-} 20 Degree-Sign , 25 Degree-Sign {+-} 20 Degree-Sign . This direction is close to the direction of the ISMF that shapes the heliosphere, l, b =33 Degree-Sign {+-} 4 Degree-Sign , 55 Degree-Sign {+-} 4 Degree-Sign , as traced by the center of the 'Ribbon' of energetic neutral atoms discovered by the Interstellar Boundary Explorer (IBEX) mission. Both the magnetic field direction and the kinematics of the local ISM are consistent with a scenario where the local ISM is a fragment of the Loop I superbubble. A nearby ordered component of the local ISMF has been identified in the region l Almost-Equal-To 0 Degree-Sign {yields} 80 Degree-Sign and b Almost-Equal-To 0 Degree-Sign {yields} 30 Degree-Sign , where PlanetPol data show a distance-dependent increase of polarization strength. The ordered component extends to within 8 pc of the Sun and implies a weak curvature in the nearby ISMF of {approx}0.{sup 0}25 pc{sup -1}. This conclusion is conditioned on the small sample of stars available for defining this rotation. Variations from the ordered component suggest a turbulent component of {approx}23 Degree-Sign . The

  15. The effects of close binaries on the magnetic activity of M dwarfs as probed using close white dwarf companions

    NASA Astrophysics Data System (ADS)

    Morgan, D. P.

    2017-01-01

    I present a study of close white dwarf (WD) and M dwarf (dM) binary systems (WD+dM) to examine the effects that close companions have on magnetic field generation in dMs. Using the Sloan Digital Sky Survey (SDSS) Data Release 8 spectroscopic database, I constructed a sample of 1756 WD+dM high-quality pairs. I show that early-type dMs (close binary systems are more likely to be magnetically active (as measured by Hα emission) and remain active longer than field dMs. Late-type dMs (>M4), where stars become fully convective, the activity fraction and activity lifetimes of WD+dM binary systems become more comparable to those of the field dMs. The implications of having a close binary companion may include: increased stellar rotation through disk disruption, tidal effects, and/or angular momentum exchange. Thus, the similarity in activity between late-type field dMs and late-type dMs with close companions is likely due to the mechanism generating magnetic fields being less sensitive to the effects caused by a close companion; namely, increased stellar rotation. Using a subset of 181 close WD+dM pairs, matched to the time-domain SDSS Stripe 82 catalog, I show that enhanced magnetic activity extends to the flaring behavior of dMs in close binaries. Specifically, early spectral type dMs (M0-M4), in close WD+dM pairs, are two orders of magnitude more likely to flare than field dMs, whereas late-type dMs (M4-M6) in close WD+dM pairs flare as frequently or less than the late-type field dM sample. To test whether the presence of a close companion leads to star-star interactions, I searched for correlations between the WD occultations and flares from the dM member in KOI-256, an eclipsing WD+dM system. I find no correlations between the flaring activity of the dM and the WD occultations, indicating the there are no obvious signs of star-star interactions at work. In addition, the dM member of KOI-256 flares more than any other dM observed by Kepler and shows evidence

  16. A model for characterizing residential ground current and magnetic field fluctuations.

    PubMed

    Mader, D L; Peralta, S B; Sherar, M D

    1994-01-01

    The current through the residential grounding circuit is an important source for magnetic fields; field variations near the grounding circuit accurately track fluctuations in this ground current. In this paper, a model is presented which permits calculation of the range of these fluctuations. A discrete network model is used to simulate a local distribution system for a single street, and a statistical model to simulate unbalanced currents in the system. Simulations of three-house and ten-house networks show that random appliance operation leads to ground current fluctuations which can be quite large, on the order of 600%. This is consistent with measured fluctuations in an actual house.

  17. Low-temperature formation of c-axis-oriented aluminum nitride thin films by plasma-assisted reactive pulsed-DC magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Takenaka, Kosuke; Satake, Yoshikatsu; Uchida, Giichiro; Setsuhara, Yuichi

    2018-01-01

    The low-temperature formation of c-axis-oriented aluminum nitride thin films was demonstrated by plasma-assisted reactive pulsed-DC magnetron sputtering. The effects of the duty cycle at the pulsed-DC voltage applied to the Al target on the properties of AlN films formed via inductively coupled plasma (ICP)-enhanced pulsed-DC magnetron sputtering deposition were investigated. With decreasing duty cycle at the target voltage, the peak intensity of AlN(0002) increased linearly. The surface roughness of AlN films decreased since there was an increase in film density owing to the impact of energetic ions on the films together with the enhancement of nitriding associated with the relative increase in N radical flux. The improvement of both the crystallinity and surface morphology of AlN films at low temperatures is considered to be caused by the difference between the relative flux values of ions and sputtered atoms.

  18. Spectroscopic imaging of self-organization in high power impulse magnetron sputtering plasmas

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Andersson, Joakim; Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, 117543 Singapore; Ni, Pavel

    Excitation and ionization conditions in traveling ionization zones of high power impulse magnetron sputtering plasmas were investigated using fast camera imaging through interference filters. The images, taken in end-on and side-on views using light of selected gas and target atom and ion spectral lines, suggest that ionization zones are regions of enhanced densities of electrons, and excited atoms and ions. Excited atoms and ions of the target material (Al) are strongly concentrated near the target surface. Images from the highest excitation energies exhibit the most localized regions, suggesting localized Ohmic heating consistent with double layer formation.

  19. Spectroscopic imaging of self-organization in high power impulse magnetron sputtering plasmas

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Centre for Quantum Technologies, National University of Singapore, 3 Science Drive 2, 117543 Singapore, Singapore; Andersson, Joakim; Ni, Pavel

    Excitation and ionization conditions in traveling ionization zones of high power impulse magnetron sputtering plasmas were investigated using fast camera imaging through interference filters. The images, taken in end-on and side on views using light of selected gas and target atom and ion spectral lines, suggest that ionization zones are regions of enhanced densities of electrons, and excited atoms and ions. Excited atoms and ions of the target material (Al) are strongly concentrated near the target surface. Images from the highest excitation energies exhibit the most localized regions, suggesting localized Ohmic heating consistent with double layer formation.

  20. Sustaining high performance: dynamic balancing in an otherwise unbalanced system.

    PubMed

    Wolf, Jason A

    2011-01-01

    As Ovid said, "There is nothing in the whole world which is permanent." It is this very premise that frames the discoveries in this chapter and the compelling paradox it has raised. What began as a question of how performance is sustained, unveiled a collection of core organizational paradoxes. The findings ultimately suggest that sustained high performance is not a permanent state an organization achieves, but rather it is through perpetual movement and dynamic balance that sustainability occurs. The idea of sustainability as movement is predicated on the ability of organizational members to move beyond the experience of paradox as an impediment to progress. Through holding three critical "movements"--agile/consistency, collective/individualism, and informative/inquiry--not as paradoxical, but as active polarities, the organizations in the study were able to transcend paradox, and take active steps to continuous achievement in outperforming their peers. The study, focused on a collection of hospitals across the Unites States, reveals powerful stories of care and service, of the profound grace of human capacity, and of clear actions taken to create significant results. All of this was achieved in an environment of great volatility, in essence an unbalanced system. It was the discovery of movement and ultimately of dynamic balancing that allowed the organizations to in this study to move beyond stasis to the continuous "state" of sustaining high performance.

  1. LETTER TO THE EDITOR: Quantum manifestations of closed orbits in the photoexcitation scaled spectrum of the hydrogen atom in crossed fields

    NASA Astrophysics Data System (ADS)

    Rao, Jianguo; Delande, D.; Taylor, K. T.

    2001-06-01

    The scaled photoexcitation spectrum of the hydrogen atom in crossed electric and magnetic fields has been obtained by means of accurate quantum mechanical calculation using a new algorithm. Closed orbits in the corresponding classical system have also been obtained, using a new, efficient and practical searching procedure. Two new classes of closed orbit have been identified. Fourier transforming each photoexcitation quantum spectrum to yield a plot against scaled action has allowed direct comparison between peaks in such plots and the scaled action values of closed orbits. Excellent agreement has been found with all peaks assigned.

  2. Analysis of frequency noise properties of 729nm extended cavity diode laser with unbalanced Mach-Zehnder interferometer

    NASA Astrophysics Data System (ADS)

    Pham, Tuan M.; Čížek, Martin; Hucl, Václav; Lazar, Josef; Hrabina, Jan; Řeřucha, Šimon; Lešundák, Adam; Obšil, Petr; Filip, Radim; Slodička, Lukáš; Číp, Ondřej

    2016-12-01

    We report on the frequency noise investigation of a linewidth-suppressed Extended Cavity Diode Laser (ECDL), working at 729 nm. Since the ECDL is intended as an excitation laser for the forbidden transition in a trapped and laser cooled 40Ca+ ion, an Hz-level linewidth is required. We present the experimental design that comprises a two-stage linewidth narrowing and a facility for frequency and noise analysis. The linewidth is first narrowed with a phase lock loop of the ECDL onto a selected component of an optical frequency comb where the frequency noise was suppressed with a fast electronic servo-loop controller that drives the laser injection current with a high bandwidth. The second stage comprises locking the laser onto a selected mode of a high-finesse passive optical cavity. The frequency analysis used an unbalanced Mach-Zehnder interferometer with a fiber spool inserted in the reference arm in order to give a general insight into the signal properties by mixing two separated beams, one of them delayed by the spool, and processing it with a spectral analyzer. Such a frequency noise analysis reveals what are the most significant noises contributions to the laser linewidth, which is a crucial information in field of ion trapping and cooling. The presented experimental results show the effect of the linewidth narrowing with the first stage, where the linewidth of ECDL was narrowed down to a kHz level.

  3. Effect of different methods of preliminary surface treatment and magnetron sputtering on the adhesion of Si coatings

    NASA Astrophysics Data System (ADS)

    Borisov, D. P.; Slabodchikov, V. A.; Kuznetsov, V. M.

    2017-05-01

    The paper presents research results on the adhesion of Si coatings deposited by magnetron sputtering on NiTi substrates after preliminary surface treatment (cleaning and activation) with low-energy ion beams and gas discharge plasma. The adhesion properties of the coatings obtained by two methods are analyzed and compared using data of scratch and spherical abrasion tests.

  4. In situ stress evolution during magnetron sputtering of transition metal nitride thin films

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Abadias, G.; Guerin, Ph.

    2008-09-15

    Stress evolution during reactive magnetron sputtering of TiN, ZrN, and TiZrN layers was studied using real-time wafer curvature measurements. The presence of stress gradients is revealed, as the result of two kinetically competing stress generation mechanisms: atomic peening effect, inducing compressive stress, and void formation, leading to a tensile stress regime predominant at higher film thickness. No stress relaxation is detected during growth interrupt in both regimes. A change from compressive to tensile stress is evidenced with increasing film thickness, Ti content, sputtering pressure, and decreasing bias voltage.

  5. Characteristics of Low-latitude Coronal Holes near the Maximum of Solar Cycle 24

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hofmeister, Stefan J.; Veronig, Astrid; Reiss, Martin A.

    We investigate the statistics of 288 low-latitude coronal holes extracted from SDO /AIA-193 filtergrams over the time range of 2011 January 01–2013 December 31. We analyze the distribution of characteristic coronal hole properties, such as the areas, mean AIA-193 intensities, and mean magnetic field densities, the local distribution of the SDO /AIA-193 intensity and the magnetic field within the coronal holes, and the distribution of magnetic flux tubes in coronal holes. We find that the mean magnetic field density of all coronal holes under study is 3.0 ± 1.6 G, and the percentaged unbalanced magnetic flux is 49 ± 16%.more » The mean magnetic field density, the mean unsigned magnetic field density, and the percentaged unbalanced magnetic flux of coronal holes depend strongly pairwise on each other, with correlation coefficients cc > 0.92. Furthermore, we find that the unbalanced magnetic flux of the coronal holes is predominantly concentrated in magnetic flux tubes: 38% (81%) of the unbalanced magnetic flux of coronal holes arises from only 1% (10%) of the coronal hole area, clustered in magnetic flux tubes with field strengths >50 G (10 G). The average magnetic field density and the unbalanced magnetic flux derived from the magnetic flux tubes correlate with the mean magnetic field density and the unbalanced magnetic flux of the overall coronal hole (cc>0.93). These findings give evidence that the overall magnetic characteristics of coronal holes are governed by the characteristics of the magnetic flux tubes.« less

  6. Electric Mars: A Large Trans-Terminator Electric Potential Drop on Closed Magnetic Field Lines Above Utopia Planitia

    NASA Technical Reports Server (NTRS)

    Collinson, Glyn; Mitchell, David; Xu, Shaosui; Glocer, Alex; Grebowsky, Joseph; Hara, Takuya; Lillis, Robert; Espley, Jared; Mazelle, Christian; Sauvaud, Jean-Andre

    2017-01-01

    Abstract Parallel electric fields and their associated electric potential structures play a crucial role inionospheric-magnetospheric interactions at any planet. Although there is abundant evidence that parallel electric fields play key roles in Martian ionospheric outflow and auroral electron acceleration, the fields themselves are challenging to directly measure due to their relatively weak nature. Using measurements by the Solar Wind Electron Analyzer instrument aboard the NASA Mars Atmosphere and Volatile EvolutioN(MAVEN) Mars Scout, we present the discovery and measurement of a substantial (Phi) Mars 7.7 +/-0.6 V) parallel electric potential drop on closed magnetic field lines spanning the terminator from day to night above the great impact basin of Utopia Planitia, a region largely free of crustal magnetic fields. A survey of the previous 26 orbits passing over a range of longitudes revealed similar signatures on seven orbits, with a mean potential drop (Phi) Mars of 10.9 +/- 0.8 V, suggestive that although trans-terminator electric fields of comparable strength are not ubiquitous, they may be common, at least at these northerly latitudes.

  7. Application of closed-form solutions to a mesh point field in silicon solar cells

    NASA Technical Reports Server (NTRS)

    Lamorte, M. F.

    1985-01-01

    A computer simulation method is discussed that provides for equivalent simulation accuracy, but that exhibits significantly lower CPU running time per bias point compared to other techniques. This new method is applied to a mesh point field as is customary in numerical integration (NI) techniques. The assumption of a linear approximation for the dependent variable, which is typically used in the finite difference and finite element NI methods, is not required. Instead, the set of device transport equations is applied to, and the closed-form solutions obtained for, each mesh point. The mesh point field is generated so that the coefficients in the set of transport equations exhibit small changes between adjacent mesh points. Application of this method to high-efficiency silicon solar cells is described; and the method by which Auger recombination, ambipolar considerations, built-in and induced electric fields, bandgap narrowing, carrier confinement, and carrier diffusivities are treated. Bandgap narrowing has been investigated using Fermi-Dirac statistics, and these results show that bandgap narrowing is more pronounced and that it is temperature-dependent in contrast to the results based on Boltzmann statistics.

  8. Simulation, fabrication and characterization of ZnO based thin film transistors grown by radio frequency magnetron sputtering.

    PubMed

    Singh, Shaivalini; Chakrabarti, P

    2012-03-01

    We report the performance of the thin film transistors (TFTs) using ZnO as an active channel layer grown by radio frequency (RF) magnetron sputtering technique. The bottom gate type TFT, consists of a conventional thermally grown SiO2 as gate insulator onto p-type Si substrates. The X-ray diffraction patterns reveal that the ZnO films are preferentially orientated in the (002) plane, with the c-axis perpendicular to the substrate. A typical ZnO TFT fabricated by this method exhibits saturation field effect mobility of about 0.6134 cm2/V s, an on to off ratio of 102, an off current of 2.0 x 10(-7) A, and a threshold voltage of 3.1 V at room temperature. Simulation of this TFT is also carried out by using the commercial software modeling tool ATLAS from Silvaco-International. The simulated global characteristics of the device were compared and contrasted with those measured experimentally. The experimental results are in fairly good agreement with those obtained from simulation.

  9. Silicon oxynitride films deposited by reactive high power impulse magnetron sputtering using nitrous oxide as a single-source precursor

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hänninen, Tuomas, E-mail: tuoha@ifm.liu.se; Schmidt, Susann; Jensen, Jens

    2015-09-15

    Silicon oxynitride thin films were synthesized by reactive high power impulse magnetron sputtering of silicon in argon/nitrous oxide plasmas. Nitrous oxide was employed as a single-source precursor supplying oxygen and nitrogen for the film growth. The films were characterized by elastic recoil detection analysis, x-ray photoelectron spectroscopy, x-ray diffraction, x-ray reflectivity, scanning electron microscopy, and spectroscopic ellipsometry. Results show that the films are silicon rich, amorphous, and exhibit a random chemical bonding structure. The optical properties with the refractive index and the extinction coefficient correlate with the film elemental composition, showing decreasing values with increasing film oxygen and nitrogen content.more » The total percentage of oxygen and nitrogen in the films is controlled by adjusting the gas flow ratio in the deposition processes. Furthermore, it is shown that the film oxygen-to-nitrogen ratio can be tailored by the high power impulse magnetron sputtering-specific parameters pulse frequency and energy per pulse.« less

  10. Microstructure, corrosion and tribological and antibacterial properties of Ti-Cu coated stainless steel.

    PubMed

    Jin, Xiaomin; Gao, Lizhen; Liu, Erqiang; Yu, Feifei; Shu, Xuefeng; Wang, Hefeng

    2015-10-01

    A Ti-Cu coated layer on 316L stainless steel (SS) was obtained by using the Closed Field Unbalanced Magnetron Sputtering (CFUBMS) system to improve antibacterial activity, corrosion and tribological properties. The microstructure and phase constituents of Ti-Cu coated layer were characterized by using X-ray diffraction (XRD), scanning electron microscopy (SEM) and glow discharge optical emission spectrometry (GDOES). The corrosion and tribological properties of a stainless steel substrate, SS316L, when coated with Ti-Cu were investigated in a simulated body fluid (SBF) environment. The viability of bacteria attached to the antibacterial surface was tested using the spread plate method. The results indicate that the Ti-Cu coated SS316L could achieve a higher corrosion polarization resistance and a more stable corrosion potential in an SBF environment than the uncoated SS316L substrate. The desirable corrosion protection performance of Ti-Cu may be attributable to the formation of a Ti-O passive layer on the coating surface, protecting the coating from further corrosion. The Ti-Cu coated SS316L also exhibited excellent wear resistance and chemical stability during the sliding tests against Si3N4 balls in SBF environment. Moreover, the Ti-Cu coatings exhibited excellent antibacterial abilities, where an effective reduction of 99.9% of Escherichia coli (E.coli) within 12h was achieved by contact with the modified surface, which was attributed to the release of copper ions when the Ti-Cu coatings are in contact with bacterial solution. Copyright © 2015 Elsevier Ltd. All rights reserved.

  11. Electrochemical properties of magnetron sputtered WO{sub 3} thin films

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Madhavi, V.; Kondaiah, P.; Hussain, O. M.

    2013-02-05

    Thin films of tungsten oxide (WO{sub 3}) were deposited on ITO substrates by using RF magnetron sputtering at oxygen and argon atmospheres of 6 Multiplication-Sign 10{sup -2}Pa and 4 Pa respectively. The chemical composition and surface morphology of the WO{sub 3} thin films have been studied by X-ray photoelectron spectroscopy (XPS) and scanning electron microscopy (SEM) respectively. The results indicate that the deposited WO{sub 3} thin films are nearly stoichiometric. The electrochemical performances of the WO{sub 3} thin films have been evaluated by galvonostatic charging/discharging method. The discharge capacity was 15{mu}Ah/cm{sup 2}{mu}m at the initial cycle and faded rapidly inmore » the first few cycles and stabilized at a lesser stage.« less

  12. RF Magnetron Sputtering Deposited W/Ti Thin Film For Smart Window Applications

    NASA Astrophysics Data System (ADS)

    Oksuz, Lutfi; Kiristi, Melek; Bozduman, Ferhat; Uygun Oksuz, Aysegul

    2014-10-01

    Electrochromic (EC) devices can change reversible and persistent their optical properties in the visible region (400-800 nm) upon charge insertion/extraction according to the applied voltage. A complementary type EC is a device containing two electrochromic layers, one of which is anodically colored such as vanadium oxide (V2 O5) while the other cathodically colored such as tungsten oxide (WO3) which is separated by an ionic conduction layer (electrolyte). The use of a solid electrolyte such as Nafion eliminates the need for containment of the liquid electrolyte, which simplifies the cell design, as well as improves safety and durability. In this work, the EC device was fabricated on a ITO/glass slide. The WO3-TiO2 thin film was deposited by reactive RF magnetron sputtering using a 2-in W/Ti (9:1%wt) target with purity of 99.9% in a mixture gas of argon and oxygen. As a counter electrode layer, V2O5 film was deposited on an ITO/glass substrate using V2O3 target with the same conditions of reactive RF magnetron sputtering. Modified Nafion was used as an electrolyte to complete EC device. The transmittance spectra of the complementary EC device was measured by optical spectrophotometry when a voltage of +/-3 V was applied to the EC device by computer controlled system. The surface morphology of the films was characterized by scanning electron microscopy (SEM) and atomic force microscopy (AFM) (Fig. 2). The cyclic voltammetry (CV) for EC device was performed by sweeping the potential between +/-3 V at a scan rate of 50 mV/s.

  13. Closed Field Coronal Heating Models Inspired by Wave Turbulence

    NASA Astrophysics Data System (ADS)

    Downs, C.; Lionello, R.; Mikic, Z.; Linker, J.; Velli, M. M.

    2013-12-01

    To simulate the energy balance of coronal plasmas on macroscopic scales, we often require the specification of the coronal heating mechanism in some functional form. To go beyond empirical formulations and to build a more physically motivated heating function, we investigate the wave-turbulence dissipation (WTD) phenomenology for the heating of closed coronal loops. To do so, we employ an implementation of non-WKB equations designed to capture the large-scale propagation, reflection, and dissipation of wave turbulence along a loop. The parameter space of this model is explored by solving the coupled WTD and hydrodynamic equations in 1D for an idealized loop, and the relevance to a range of solar conditions is established by computing solutions for several hundred loops extracted from a realistic 3D coronal field. Due to the implicit dependence of the WTD heating model on loop geometry and plasma properties along the loop and at the footpoints, we find that this model can significantly reduce the number of free parameters when compared to traditional empirical heating models, and still robustly describe a broad range of quiet-sun and active region conditions. The importance of the self-reflection term in producing realistic heating scale heights and thermal non-equilibrium cycles is discussed, and preliminary 3D thermodynamic MHD simulations using this formulation are presented. Research supported by NASA and NSF.

  14. Unbalanced-flow, fluid-mixing plug with metering capabilities

    NASA Technical Reports Server (NTRS)

    England, John Dwight (Inventor); Kelley, Anthony R. (Inventor); Van Buskirk, Paul D. (Inventor)

    2009-01-01

    A fluid mixer plug has holes formed therethrough such that a remaining portion is closed to fluid flow. The plug's inlet face defines a central circuit region and a ring-shaped region with the ring-shaped region including at least some of the plug's remaining portion so-closed to fluid flow. This remaining portion or closed region at each radius R of the ring shaped region satisfies a radius independent, flow-based relationship. Entry openings are defined in the plug's inlet face in correspondence with the holes. The entry openings define an open flow area at each radius of the ring-shaped region. The open flow area at each such radius satisfies the inverse of the flow-based relationship defining the closed regions of the plug.

  15. The target material influence on the current pulse during high power pulsed magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Moens, Filip; Konstantinidis, Stéphanos; Depla, Diederik

    2017-10-01

    The current-time characteristic during high power pulsed magnetron sputtering is measured under identical conditions for seventeen different target materials. Based on physical processes such as gas rarefaction, ion-induced electron emission, and electron impact ionization, two test parameters were derived that significantly correlate with specific features of the current-time characteristic: i) the peak current is correlated to the momentum transfer between the sputtered material and the argon gas, ii) while the observed current plateau after the peak is connected to the metal ionization rate.

  16. The retest distribution of the visual field summary index mean deviation is close to normal.

    PubMed

    Anderson, Andrew J; Cheng, Allan C Y; Lau, Samantha; Le-Pham, Anne; Liu, Victor; Rahman, Farahnaz

    2016-09-01

    When modelling optimum strategies for how best to determine visual field progression in glaucoma, it is commonly assumed that the summary index mean deviation (MD) is normally distributed on repeated testing. Here we tested whether this assumption is correct. We obtained 42 reliable 24-2 Humphrey Field Analyzer SITA standard visual fields from one eye of each of five healthy young observers, with the first two fields excluded from analysis. Previous work has shown that although MD variability is higher in glaucoma, the shape of the MD distribution is similar to that found in normal visual fields. A Shapiro-Wilks test determined any deviation from normality. Kurtosis values for the distributions were also calculated. Data from each observer passed the Shapiro-Wilks normality test. Bootstrapped 95% confidence intervals for kurtosis encompassed the value for a normal distribution in four of five observers. When examined with quantile-quantile plots, distributions were close to normal and showed no consistent deviations across observers. The retest distribution of MD is not significantly different from normal in healthy observers, and so is likely also normally distributed - or nearly so - in those with glaucoma. Our results increase our confidence in the results of influential modelling studies where a normal distribution for MD was assumed. © 2016 The Authors Ophthalmic & Physiological Optics © 2016 The College of Optometrists.

  17. A star tracker insensitive to stray light generated by radiation sources close to the field of view

    NASA Astrophysics Data System (ADS)

    Romoli, A.; Gambicorti, L.; Simonetti, F.; Zuccaro Marchi, A.

    2017-11-01

    Aim of this work is to propose an innovative star tracker, practically insensitive to the radiation coming from the sun or from other strong planetary sources out of (but near) the Field of View. These sources need to be stopped in some way. The classical solution to reject the unwanted radiation is to place a shadow (or baffle) before the star tracker objective. The shadow size depends on the Field of View and on the minimum angle subtended by the source (i.e. the sun) with respect to the optical axis of the star tracker. The lower is this angle the larger is the shadow. Requests for star trackers able to work with the sun as close as possible to the Field of View are increasing, due to the need of maximum mission flexibility. The innovation of this proposed star tracker is conceived by using spatial filtering with a concept complementary to that of coronagraph for sun corona observation, allowing to drastically reduce the size of the shadow. It can also work close to antennas and other part of the platform, which, when illuminated by the sun, become secondary sources capable to blind the star tracker. This kind of accommodation offers three main advantages: no cumbersome shadows (baffle), maximum flexibility in terms of mission profile, less platform location constraints. This new star sensor concept, dated 2007, is now patent pending. Galileo Avionica (now Selex Galileo) is the owner of the patent.

  18. φ-OTDR sensing system with bidirectional pumped fiber Raman amplifier and unbalanced MZ interferometer

    NASA Astrophysics Data System (ADS)

    Zhang, Liang; Tian, Ming; Dong, Lei

    2017-10-01

    In order to improve the detection distance and the sensitivity, we propose a novel distributed optical fiber sensing system. This system is composed of bidirectional pumping fiber Raman amplifier and unbalanced fiber Mach-Zehnder interferometer. Based on the interference mechanism of phase sensitive optical time domain reflectometer (φ-OTDR), the system can get the sensing information of the whole optical fiber by analyzing the backward scattered light. The interferometer is used as the demodulator of the sensing system, which consists of a 3×3 coupler and two faraday rotator mirrors. By means of the demodulator, the signal light is divided into three beams with fixed phase difference. To deal with these three signals, we can get the vibration information directly on the optical fiber. Through experimental study, this system has a high sensitivity. The maximum sensing length and the spatial resolution of the φ-OTDR system are 100 km and 10 m. The signal to noise ratio about 18 dB is achieved.

  19. Sparse Coding and Lateral Inhibition Arising from Balanced and Unbalanced Dendrodendritic Excitation and Inhibition

    PubMed Central

    Migliore, Michele; Hines, Michael L.; Shepherd, Gordon M.

    2014-01-01

    The precise mechanism by which synaptic excitation and inhibition interact with each other in odor coding through the unique dendrodendritic synaptic microcircuits present in olfactory bulb is unknown. Here a scaled-up model of the mitral–granule cell network in the rodent olfactory bulb is used to analyze dendrodendritic processing of experimentally determined odor patterns. We found that the interaction between excitation and inhibition is responsible for two fundamental computational mechanisms: (1) a balanced excitation/inhibition in strongly activated mitral cells, leading to a sparse representation of odorant input, and (2) an unbalanced excitation/inhibition (inhibition dominated) in surrounding weakly activated mitral cells, leading to lateral inhibition. These results suggest how both mechanisms can carry information about the input patterns, with optimal level of synaptic excitation and inhibition producing the highest level of sparseness and decorrelation in the network response. The results suggest how the learning process, through the emergent development of these mechanisms, can enhance odor representation of olfactory bulb. PMID:25297097

  20. Low Temperature Unbalanced Magnetron Deposition of Hard, Wear-Resistant Coatings for Liquid-Film Bearing Applications

    NASA Technical Reports Server (NTRS)

    Sproul, William D.

    1996-01-01

    The original program for evaluating the tribological properties several different hard coatings for liquid film bearing applications was curtailed when the time for the program was reduced from 3 years to 1. Of the several different coatings originally planned for evaluation, we decided to concentrate on one coating, carbon nitride. At BIRL, we have been instrumental in the development of reactively sputtered carbon nitride coatings, and we have found that it is a very interesting new material with very good tribological properties. In this program, we found that the reactively sputtered carbon nitride does not bond well directly to hardened 440C stainless steel; but if an interlayer of titanium nitride is added between the carbon nitride and the 440C, the adhesion of the dual coating combination is very good. Statistically designed experiments were run with the dual layer combination, and 3 variables were chosen for the Box-Benken design, which were the titanium nitride interlayer thickness, the nitrogen partial pressure during the reactive sputtering of the carbon nitride, and the carbon nitride substrate bias voltage. Two responses were studied from these three variables; the adhesion of the dual coating combination to the 440C substrate and the friction coefficient of the carbon nitride in dry sliding contact with 52100 steel in air. The best adhesion came with the thickness interlayer thickness studied, which was 4 micrometers, and the lowest coefficient of friction was 0.1, which was achieved when the bias voltage was in the range of -80 to - 120 V and the nitrogen partial pressure was 3 mTorr.

  1. Simple Genetic Distance-Optimized Field Deployments for Clonal Seed Orchards Based on Microsatellite Markers: As a Case of Chinese Pine Seed Orchard.

    PubMed

    Yuan, Huwei; Niu, Shihui; El-Kassaby, Yousry A; Li, Yue; Li, Wei

    2016-01-01

    Chinese pine seed orchards are in a period of transition from first-generation to advanced-generations. How to effectively select populations for second-generation seed orchards and significantly increase genetic gain through rational deployment have become major issues. In this study, we examined open- and control-pollinated progeny of the first-generation Chinese pine seed orchards in Zhengning (Gansu Province, China) and Xixian (Shanxi Province, China) to address issues related to phenotypic selection for high volume growth, genetic diversity analysis and genetic distance-based phylogenetic analysis of the selections by simple sequence repeats (SSRs), and phylogenetic relationship-based field deployment for advanced-generation orchards. In total, 40, 28, 20, and 13 superior individuals were selected from the large-scale no-pedigree open-pollinated progeny of Zhengning (ZN-NP), open-pollinated families of Zhengning (ZN-OP), open-pollinated families of Xixian (XX-OP), and control-pollinated families of Xixian, with mean volume dominance ratios of 0.83, 0.15, 0.25, and 0.20, respectively. Phylogenetic relationship analysis of the ZN-NP and XX-OP populations showed that the 40 superior individuals in the ZN-NP selected population belonged to 23 families and could be further divided into five phylogenetic groups, and that families in the same group were closely related. Similarly, 20 families in the XX-OP population were related to varying degrees. Based on these results, we found that second-generation Chinese pine seed orchards in Zhengning and Xixian should adopt a grouped, unbalanced, complete, fixed block design and an unbalanced, incomplete, fixed block design, respectively. This study will provide practical references for applying molecular markers to establishing advanced-generation seed orchards.

  2. Facing-target mid-frequency magnetron reactive sputtered hafnium oxide film: Morphology and electrical properties

    NASA Astrophysics Data System (ADS)

    Zhang, Yu; Xu, Jun; Wang, You-Nian; Choi, Chi Kyu; Zhou, Da-Yu

    2016-03-01

    Amorphous hafnium dioxide (HfO2) film was prepared on Si (100) by facing-target mid-frequency reactive magnetron sputtering under different oxygen/argon gas ratio at room temperature with high purity Hf target. 3D surface profiler results showed that the deposition rates of HfO2 thin film under different O2/Ar gas ratio remain unchanged, indicating that the facing target midfrequency magnetron sputtering system provides effective approach to eliminate target poisoning phenomenon which is generally occurred in reactive sputtering procedure. X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) demonstrated that the gradual reduction of oxygen vacancy concentration and the densification of deposited film structure with the increase of oxygen/argon (O2/Ar) gas flow ratio. Atomic force microscopy (AFM) analysis suggested that the surface of the as-deposited HfO2 thin film tends to be smoother, the root-meansquare roughness (RMS) reduced from 0.876 nm to 0.333 nm while O2/Ar gas flow ratio increased from 1/4 to 1/1. Current-Voltage measurements of MOS capacitor based on Au/HfO2/Si structure indicated that the leakage current density of HfO2 thin films decreased by increasing of oxygen partial pressure, which resulted in the variations of pore size and oxygen vacancy concentration in deposited thin films. Based on the above characterization results the leakage current mechanism for all samples was discussed systematically.

  3. Deposition of vanadium oxide films by direct-current magnetron reactive sputtering

    NASA Astrophysics Data System (ADS)

    Kusano, E.; Theil, J. A.; Thornton, John A.

    1988-06-01

    It is demonstrated here that thin films of vanadium oxide can be deposited at modest substrate temperatures by dc reactive sputtering from a vanadium target in an O2-Ar working gas using a planar magnetron source. Resistivity ratios of about 5000 are found between a semiconductor phase with a resistivity of about 5 Ohm cm and a metallic phase with a resistivity of about 0.001 Ohm cm for films deposited onto borosilicate glass substrates at about 400 C. X-ray diffraction shows the films to be single-phase VO2 with a monoclinic structure. The VO2 films are obtained for a narrow range of O2 injection rates which correspond to conditions where cathode poisoning is just starting to occur.

  4. Deposition of vanadium oxide films by direct-current magnetron reactive sputtering

    NASA Technical Reports Server (NTRS)

    Kusano, E.; Theil, J. A.; Thornton, John A.

    1988-01-01

    It is demonstrated here that thin films of vanadium oxide can be deposited at modest substrate temperatures by dc reactive sputtering from a vanadium target in an O2-Ar working gas using a planar magnetron source. Resistivity ratios of about 5000 are found between a semiconductor phase with a resistivity of about 5 Ohm cm and a metallic phase with a resistivity of about 0.001 Ohm cm for films deposited onto borosilicate glass substrates at about 400 C. X-ray diffraction shows the films to be single-phase VO2 with a monoclinic structure. The VO2 films are obtained for a narrow range of O2 injection rates which correspond to conditions where cathode poisoning is just starting to occur.

  5. Stepwise occurrence of a complex unbalanced translocation in neuroblastoma leading to insertion of a telomere sequence and late chromosome 17q gain.

    PubMed

    Schleiermacher, Gudrun; Bourdeaut, Franck; Combaret, Valérie; Picrron, Gaelle; Raynal, Virginie; Aurias, Alain; Ribeiro, Agnes; Janoueix-Lerosey, Isabelle; Delattre, Olivier

    2005-05-05

    In neuroblastoma, the most frequent genetic alterations are unbalanced translocations involving chromosome 17. To gain insights into these rearrangements, we have characterized a previously identified der(1)t(1;17) of the CLB-Bar cell line. The 17q breakpoint was mapped by FISH. Subsequently, a rearranged fragment was identified by Southern analysis, cloned in a lambda vector and sequenced. The chromosome rearrangement is more complex than expected due to the presence of an interstitial 4p telomeric sequence between chromosome 1p and 17q. Three different genes, which may play a role in neuroblastoma development, are disrupted by the translocation breakpoints. Indeed, the 3'UTR of the PIP5K2B gene on chromosome 17q is directly fused to the (TTAGGG)n repeat of the chromosome 4p telomere, and the (1;4) fusion disrupts the MACF1 (microtubule-actin crosslinking factor 1) and POLN genes, respectively. Interestingly, the (1;4) fusion was present at diagnosis and at relapse, whereas the (4;17) fusion was detected at relapse only, leading to a secondary 17q gain confirmed by array CGH therefore indicating that 17q gain may not be a primary event in neuroblastoma. Finally, screening of a panel of neuroblastoma cell lines identified interstitial telomeric sequences in three other cases, suggesting that this may be a recurrent mechanism leading to unbalanced translocations in neuroblastoma.

  6. Raman and PEELS studies of magnetron sputtered a-C

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zhang, S.; Jen, T.M.; Zeng, X.

    Amorphous carbon coatings (a-C, a-C:H) of less than 100 nm thick were deposited on KBr pellets and silicon wafer substrate via magnetron sputtering of graphic target in argon, argon/hydrogen and argon/nitrogen atmosphere. Parallel electron energy loss spectroscopy (PEELS) analysis was used to quantify the sp{sup 2}/sp{sup 3} bonding in carbon films. Stand-alone films of amorphous carbon were produced by sputtering onto compressed KBr pellets and then floating off in distilled water for PEELS study. Raman spectroscopy was used to measure the peak intensity ratio of D-band to that of the G-band (I{sub d}/I{sub g}). It shows that higher sp{sup 3}more » fraction often associates with Raman peak ratio I{sub d}/I{sub g}. At the same time, G-band peak position P{sub g} decreases while sp{sup 3} fraction increases.« less

  7. Cobalt Modification of Thin Rutile Films Magnetron-Sputtered in Vacuum

    NASA Astrophysics Data System (ADS)

    Afonin, N. N.; Logacheva, V. A.

    2018-04-01

    Using X-ray phase analysis, atomic force microscopy, and secondary ion mass-spectrometry, the phase formation and component distribution in a Co-TiO2 film system have been investigated during magnetron sputtering of the metal on the oxide and subsequent vacuum annealing. It has been found that cobalt diffuses deep into titanium oxide to form complex oxides CoTi2O5 and CoTiO3. A mechanism behind their formation at grain boundaries throughout the thickness of the TiO2 film is suggested. It assumes the reactive diffusion of cobalt along grain boundaries in the oxide. A quantitative model of reactive interdiffusion in a bilayer polycrystalline metal-oxide film system with limited solubility of components has been developed. The individual diffusion coefficients of cobalt and titanium have been determined in the temperature interval 923-1073 K.

  8. THE INFLUENCE OF MAGNETIC FIELD GEOMETRY ON THE FORMATION OF CLOSE-IN EXOPLANETS

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Simon, Jacob B., E-mail: jbsimon.astro@gmail.com

    2016-08-20

    Approximately half of Sun-like stars harbor exoplanets packed within a radius of ∼0.3 au, but the formation of these planets and why they form in only half of known systems are still not well understood. We employ a one-dimensional steady-state model to gain physical insight into the origin of these close-in exoplanets. We use Shakura and Sunyaev α values extracted from recent numerical simulations of protoplanetary disk accretion processes in which the magnitude of α , and thus the steady-state gas surface density, depend on the orientation of large-scale magnetic fields with respect to the disk’s rotation axis. Solving formore » the metallicity as a function of radius, we find that for fields anti-aligned with the rotation axis, the inner regions of our model disk often fall within a region of parameter space that is not suitable for planetesimal formation, whereas in the aligned case, the inner disk regions are likely to produce planetesimals through some combination of streaming instability and gravitational collapse, though the degree to which this is true depends on the assumed parameters of our model. More robustly, the aligned field case always produces higher concentrations of solids at small radii compared to the anti-aligned case. In the in situ formation model, this bimodal distribution of solid enhancement leads directly to the observed dichotomy in exoplanet orbital distances.« less

  9. Inter- and intra-guild interactions related to aphids in nettle (Urtica dioica L.) strips closed to field crops.

    PubMed

    Alhmedi, A; Haubruge, E; Bodson, B; Francis, F

    2006-01-01

    A field experiment designed to assess the biodiversity related to nettle strips closed to crops, and more particularly the aphid and related beneficial populations, was established in experimental farm located in Gembloux (Belgium). Margin strips of nettle (Urtica dioica) closed to wheat (Triticum aestivum), green pea (Pisum sativum) and rape (Brassicae napus) fields were investigated. The diversity, abundance of aphids and related predators were analysed according to the plant crop species and the differential pesticide application (treated plot and control). Insects were visually observed every week during all the cultivation season. Two main families of aphidophagous predators were found in all field crops and nettle, the Coccinellidae and Syrphidae. The diversity of the aphidophagous predators was shown to be higher on nettle than in field crops, particularly the Chrysopidae, the Anthocoridae and the Miridae. However, a striking difference of ladybird abundance was observed according to the aphid host plant. In one side, Coccinella septempunctata was much more abundant on Acyrthosiphon pisum infested green pea than on the other host plant species. At the opposite, higher occurrence of Harmonia axyridis was observed on the aphid infested nettle plants than on the crop plants. In particular, none of H. axyridis was found in wheat crop. Also, more than only a significant positive correlation between predator and aphid abundance, specialised relations between particular aphid species and some so-called generalist predators was determined in the fields. Finally, intraguild interactions between the aphidophagous predators was assessed and shown that only a significant negative correlation between Episyrphus balteatus and H. axyridis related to the nettle aphid, Micrlophium carnosum, was observed. The relative distribution of the ladybirds, namely C. septempunctata and H. axyridis according to the host plant, nettle strips and crop plots was discussed in relation to

  10. [A survey on the dietary and health habits according to action styles for unbalanced diets among female university students].

    PubMed

    Nagashima, Kumiko; Sakaguchi, Sanae; Sakaguchi, Takehiro

    2002-05-01

    A survey of woman's students, who had grown up in a time of change-over of Japanese customs regarding food, was conducted to investigate dietary habits, a focus on actions in response to with set needs, The aim was to obtain to measure prospective health maintenance and promotion. The authors carried out a questionnaire for woman's students in 6 universities of Kanto area (a junior college and graduate courses were included) in years 1999 and 2000. In actions regarding the diet, 19.1% of the 815 students responded "I eat everything without fail", 17.7% "I eat almost everything irrespective of likes and dislikes", 24.5% "I strive to eat everything", 19.8% "I leave almost everything I dislike", and 18.5% "I don't eat what I dislike". The students who responded "I leave almost everything I dislike" and "I don't eat what I dislike" had low scores in the questionnaire for dietary and health habits, and they tended to like noodles and popular snacks, and also made frequent use of fast food restaurants. There was not a problem with the majority, but about 30% of the students were judged as confirming an unbalanced diet by this questionnaire. It was found that there were "gaps" and "bad habits" in the regular diet. Moreover, we recognized a tendency to prefer convenience and taste to nutritional balance. This simple questionnaire is suitable for rapid identification of unbalanced distory habits, and both "gaps" and "bad habits" in the regular system diet. It is the most important that we induce students who leave or don't eat what they dislike, to strive to eat everything, irrespective of likes and dislikes.

  11. Close-field electroporation gene delivery using the cochlear implant electrode array enhances the bionic ear.

    PubMed

    Pinyon, Jeremy L; Tadros, Sherif F; Froud, Kristina E; Y Wong, Ann C; Tompson, Isabella T; Crawford, Edward N; Ko, Myungseo; Morris, Renée; Klugmann, Matthias; Housley, Gary D

    2014-04-23

    The cochlear implant is the most successful bionic prosthesis and has transformed the lives of people with profound hearing loss. However, the performance of the "bionic ear" is still largely constrained by the neural interface itself. Current spread inherent to broad monopolar stimulation of the spiral ganglion neuron somata obviates the intrinsic tonotopic mapping of the cochlear nerve. We show in the guinea pig that neurotrophin gene therapy integrated into the cochlear implant improves its performance by stimulating spiral ganglion neurite regeneration. We used the cochlear implant electrode array for novel "close-field" electroporation to transduce mesenchymal cells lining the cochlear perilymphatic canals with a naked complementary DNA gene construct driving expression of brain-derived neurotrophic factor (BDNF) and a green fluorescent protein (GFP) reporter. The focusing of electric fields by particular cochlear implant electrode configurations led to surprisingly efficient gene delivery to adjacent mesenchymal cells. The resulting BDNF expression stimulated regeneration of spiral ganglion neurites, which had atrophied 2 weeks after ototoxic treatment, in a bilateral sensorineural deafness model. In this model, delivery of a control GFP-only vector failed to restore neuron structure, with atrophied neurons indistinguishable from unimplanted cochleae. With BDNF therapy, the regenerated spiral ganglion neurites extended close to the cochlear implant electrodes, with localized ectopic branching. This neural remodeling enabled bipolar stimulation via the cochlear implant array, with low stimulus thresholds and expanded dynamic range of the cochlear nerve, determined via electrically evoked auditory brainstem responses. This development may broadly improve neural interfaces and extend molecular medicine applications.

  12. Influence of stress on the structural and dielectric properties of rf magnetron sputtered zinc oxide thin film

    NASA Astrophysics Data System (ADS)

    Menon, Rashmi; Sreenivas, K.; Gupta, Vinay

    2008-05-01

    Highly c axis oriented zinc oxide (ZnO) thin films have been prepared on 1737 Corning glass substrate by planar rf magnetron sputtering under varying pressure (10-50mTorr) and different oxygen percentage (40%-100%) in reactive gas mixtures. The as-grown ZnO thin films were found to have stress over a wide range from -6×1010to-9×107dynes/cm2. The presence of stress depends strongly on processing conditions, and films become almost stress free under a unique combination of sputtering pressure and reactive gas composition. The studies show a correlation of stress with structural and electrical properties of the ZnO thin film. The stressed films possess high electrical conductivity and exhibits strong dielectric dispersion over a wide frequency (1kHz-1MHz). The dielectric constant ɛ'(ω) of stress free ZnO film was almost frequency independent and was close to the bulk value. The measured value of dc conductivity, σdc(ω) and ac conductivity σac(ω) of stress free ZnO film was 1.3×10-9 and 6.8×10-5Ω-1cm-1, respectively. The observed variation in the structural and electrical properties of ZnO thin film with stress has been analyzed in the light of growth kinetics.

  13. Open and closed loop manipulation of charged microchiplets in an electric field

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Lu, J. P., E-mail: jplu@parc.com; Thompson, J. D.; Whiting, G. L.

    We demonstrate the ability to orient, position, and transport microchips (“chiplets”) with electric fields. In an open-loop approach, modified four phase traveling wave potential patterns manipulate chiplets in a dielectric solution using dynamic template agitation techniques. Repeatable parallel assembly of chiplets is demonstrated to a positional accuracy of 6.5 μm using electrodes of 200 μm pitch. Chiplets with dipole surface charge patterns are used to show that orientation can be controlled by adding unique charge patterns on the chiplets. Chip path routing is also demonstrated. With a closed-loop control system approach using video feedback, dielectric, and electrophoretic forces are used to achievemore » positioning accuracy of better than 1 μm with 1 mm pitch driving electrodes. These chip assembly techniques have the potential to enable future printer systems where inputs are electronic chiplets and the output is a functional electronic system.« less

  14. BiVO{sub 4} photoanodes for water splitting with high injection efficiency, deposited by reactive magnetron co-sputtering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Gong, Haibo; Institute for Solar Fuels, Helmholtz-Zentrum Berlin für Materialien und Energie GmbH, Hahn-Meitner-Platz 1, 14109 Berlin; Freudenberg, Norman

    2016-04-15

    Photoactive bismuth vanadate (BiVO{sub 4}) thin films were deposited by reactive co-magnetron sputtering from metallic Bi and V targets. The effects of the V-to-Bi ratio, molybdenum doping and post-annealing on the crystallographic and photoelectrochemical (PEC) properties of the BiVO{sub 4} films were investigated. Phase-pure monoclinic BiVO{sub 4} films, which are more photoactive than the tetragonal BiVO{sub 4} phase, were obtained under slightly vanadium-rich conditions. After annealing of the Mo-doped BiVO{sub 4} films, the photocurrent increased 2.6 times compared to undoped films. After optimization of the BiVO{sub 4} film thickness, the photocurrent densities (without a catalyst or a blocking layer ormore » a hole scavenger) exceeded 1.2 mA/cm{sup 2} at a potential of 1.23 V{sub RHE} under solar AM1.5 irradiation. The surprisingly high injection efficiency of holes into the electrolyte is attributed to the highly porous film morphology. This co-magnetron sputtering preparation route for photoactive BiVO{sub 4} films opens new possibilities for the fabrication of large-scale devices for water splitting.« less

  15. Relationship between plasma parameters and film microstructure in radio frequency magnetron sputter deposition of barium strontium titanate

    NASA Astrophysics Data System (ADS)

    Panda, B.; Dhar, A.; Nigam, G. D.; Bhattacharya, D.; Ray, S. K.

    1998-01-01

    Radio frequency magnetron sputtered Ba0.8Sr0.2TiO3 thin films have been deposited on silicon and Si/SiO2/SiN/Pt substrates. The analysis of plasma discharge has been carried out using the Langmuir probe technique. Both the pressure and power have been found to influence the ion density and self-bias of the target. Introduction of oxygen into the discharge effectively decreases the ion density. The structural and electrical properties have been investigated using x-ray diffraction, atomic force microscopy of deposited films and capacitance-voltage, conductance-voltage, and current density-electric field characteristics of fabricated capacitors. The growth and orientation of the films have been found to depend upon the type of substrates and deposition temperatures. The <100> texture in the film is promoted at a pressure 0.25 Torr with a moderately high value of ion density and low ion bombardment energy. Films deposited on Si/SiO2/SiN/Pt substrate have shown higher dielectric constant (191) and lower leakage current density (2.8×10-6 A/cm2 at 100 kV/cm) compared to that on silicon.

  16. Structural, Electrical and Optical Properties of Cd Doped ZnO Thin Films by Reactive dc Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    Kumar, A. Guru Sampath; Obulapathi, L.; Sarmash, T. Sofi; Rani, D. Jhansi; Maddaiah, M.; Rao, T. Subba; Asokan, K.

    2015-04-01

    Thin films of cadmium (Cd) (0 wt.%, 2 wt.%, 4 wt.% and 10 wt.%) doped zinc oxide (ZnO) have been deposited on a glass substrate by reactive DC magnetron sputtering. The synthesized films are characterized by glancing angle x-ray diffraction (GAXRD), UV-Vis-NIR spectroscopy, four probe resistivity measurement, Hall measurement system, field emission-scanning electron microscopy and energy dispersive analysis by x-rays. A systematic study has been made on the structure, electrical and optical properties of Cd doped ZnO thin films as a function of Cd concentration (0 wt.%, 2 wt.%, 4 wt.% and 10 wt.%). All these films have a hexagonal wurtzite ZnO structure with (0 0 2) orientation without any Cd related phase from the GAXRD patterns. The grain size was increased and maximum appears at 4 wt.% Cd concentration. The electrical resistivity of the films decreased with the Cd doping and minimum resistivity was observed at 4 wt.% Cd concentration. UV-Vis-NIR studies showed that the optical band gap of ZnO (3.37 eV) was reduced to 3.10 eV which is at 4 wt.% Cd concentration.

  17. Using Close White Dwarf + M Dwarf Stellar Pairs to Constrain the Flare Rates in Close Stellar Binaries

    NASA Astrophysics Data System (ADS)

    Morgan, Dylan P.; West, Andrew A.; Becker, Andrew C.

    2016-05-01

    We present a study of the statistical flare rates of M dwarfs (dMs) with close white dwarf (WD) companions (WD+dM; typical separations <1 au). Our previous analysis demonstrated that dMs with close WD companions are more magnetically active than their field counterparts. One likely implication of having a close binary companion is increased stellar rotation through disk-disruption, tidal effects, and/or angular momentum exchange; increased stellar rotation has long been associated with an increase in stellar activity. Previous studies show a strong correlation between dMs that are magnetically active (showing Hα in emission) and the frequency of stellar flare rates. We examine the difference between the flare rates observed in close WD+dM binary systems and field dMs. Our sample consists of a subset of 181 close WD+dM pairs from Morgan et al. observed in the Sloan Digital Sky Survey Stripe 82, where we obtain multi-epoch observations in the Sloan ugriz-bands. We find an increase in the overall flaring fraction in the close WD+dM pairs (0.09 ± 0.03%) compared to the field dMs (0.0108 ± 0.0007%) and a lower flaring fraction for active WD+dMs (0.05 ± 0.03%) compared to active dMs (0.28 ± 0.05%). We discuss how our results constrain both the single and binary dM flare rates. Our results also constrain dM multiplicity, our knowledge of the Galactic transient background, and may be important for the habitability of attending planets around dMs with close companions.

  18. Methods of Using a Magnetic Field Response Sensor Within Closed, Electrically Conductive Containers

    NASA Technical Reports Server (NTRS)

    Woodward, Stanley E.; Taylor, Bryant D.

    2010-01-01

    Magnetic field response sensors are a class of sensors that are powered via oscillating magnetic fields, and when electrically active, respond with their own magnetic fields with attributes dependent upon the magnitude of the physical quantity being measured. A magnetic field response recorder powers and interrogates the magnetic sensors [see Magnetic-Field-Response Measurement- Acquisition System, NASA Tech Briefs Vol. 30, No, 6 (June 2006, page 28)]. Electrically conductive containers have low transmissivity for radio frequency (RF) energy and thus present problems for magnetic field response sensors. It is necessary in some applications to have a magnetic field response sensor s capacitor placed in these containers. Proximity to conductive surfaces alters the inductance and capacitance of the sensors. As the sensor gets closer to a conductive surface, the electric field and magnetic field energy of the sensor is reduced due to eddy currents being induced in the conductive surface. Therefore, the capacitors and inductors cannot be affixed to a conductive surface or embedded in a conductive material. It is necessary to have a fixed separation away from the conductive material. The minimum distance for separation is determined by the desired sensor response signal to noise ratio. Although the inductance is less than what it would be if it were not in proximity to the conductive surface, the inductance is fixed. As long as the inductance is fixed, all variations of the magnetic field response are due to capacitance changes. Numerous variations of inductor mounting can be utilized, such as providing a housing that provides separation from the conductive material as well as protection from impact damage. The sensor can be on the same flexible substrate with a narrow throat portion of the sensor between the inductor and the capacitor, Figure 1. The throat is of sufficient length to allow the capacitor to be appropriately placed within the container and the inductor

  19. The effects of film thickness on the electrical, optical, and structural properties of cylindrical, rotating, magnetron-sputtered ITO films

    NASA Astrophysics Data System (ADS)

    Kim, Jae-Ho; Seong, Tae-Yeon; Ahn, Kyung-Jun; Chung, Kwun-Bum; Seok, Hae-Jun; Seo, Hyeong-Jin; Kim, Han-Ki

    2018-05-01

    We report the characteristics of Sn-doped In2O3 (ITO) films intended for use as transparent conducting electrodes; the films were prepared via a five-generation, in-line type, cylindrical, rotating magnetron sputtering (CRMS) system as a function of film thickness. By using a rotating cylindrical ITO target with high usage (∼80%), we prepared high conductivity, transparent ITO films on five-generation size glass. The effects of film thickness on the electrical, optical, morphological, and structural properties of CRMS-grown ITO films are investigated in detail to correlate the thickness and performance of ITO films. The preferred orientation changed from the (2 2 2) to the (4 0 0) plane with increasing thickness of ITO is attributed to the stability of the (4 0 0) plane against resputtering during the CRMS process. Based on X-ray diffraction, surface field emission scanning electron microscopy, and cross-sectional transmission electron microscopy, we suggest a possible mechanism to explain the preferred orientation and effects of film thickness on the performance of CRMS-grown ITO films.

  20. Structure and morphology of magnetron sputter deposited ultrathin ZnO films on confined polymeric template

    NASA Astrophysics Data System (ADS)

    Singh, Ajaib; Schipmann, Susanne; Mathur, Aakash; Pal, Dipayan; Sengupta, Amartya; Klemradt, Uwe; Chattopadhyay, Sudeshna

    2017-08-01

    The structure and morphology of ultra-thin zinc oxide (ZnO) films with different film thicknesses on confined polymer template were studied through X-ray reflectivity (XRR) and grazing incidence small angle X-ray scattering (GISAXS). Using magnetron sputter deposition technique ZnO thin films with different film thicknesses (<10 nm) were grown on confined polystyrene with ∼2Rg film thickness, where Rg ∼ 20 nm (Rg is the unperturbed radius of gyration of polystyrene, defined by Rg = 0.272 √M0, and M0 is the molecular weight of polystyrene). The detailed internal structure, along the surface/interfaces and the growth direction of the system were explored in this study, which provides insight into the growth procedure of ZnO on confined polymer and reveals that a thin layer of ZnO, with very low surface and interface roughness, can be grown by DC magnetron sputtering technique, with approximately full coverage (with bulk like electron density) even in nm order of thickness, in 2-7 nm range on confined polymer template, without disturbing the structure of the underneath template. The resulting ZnO-polystyrene hybrid systems show strong ZnO near band edge (NBE) and deep-level (DLE) emissions in their room temperature photoluminescence spectra, where the contribution of DLE gets relatively stronger with decreasing ZnO film thickness, indicating a significant enhancement of surface defects because of the greater surface to volume ratio in thinner films.

  1. On the longitudinal distribution of electric field in the acceleration zones of plasma accelerators and thrusters with closed electron drift

    NASA Astrophysics Data System (ADS)

    Kim, V. P.

    2017-04-01

    The long-term experience in controlling the electric field distribution in the discharge gaps of plasma accelerators and thrusters with closed electron drift and the key ideas determining the concepts of these devices and tendencies of their development are analyzed. It is shown that an electrostatic mechanism of ion acceleration in plasma by an uncompensated space charge of the cloud of magnetized electrons "kept" to the magnetic field takes place in the acceleration zones and that the electric field distribution can be controlled by varying the magnetic field in the discharge gap. The role played by the space charge makes the mechanism of ion acceleration in this type of thrusters is fundamentally different from the acceleration mechanism operating in purely electrostatic thrusters.

  2. Ion energies in high power impulse magnetron sputtering with and without localized ionization zones

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yang, Yuchen; Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720; Tanaka, Koichi

    2015-03-23

    High speed imaging of high power impulse magnetron sputtering discharges has revealed that ionization is localized in moving ionization zones but localization disappears at high currents for high yield targets. This offers an opportunity to study the effect ionization zones have on ion energies. We measure that ions have generally higher energies when ionization zones are present, supporting the concept that these zones are associated with moving potential humps. We propose that the disappearance of ionization zones is caused by an increased supply of atoms from the target which cools electrons and reduces depletion of atoms to be ionized.

  3. Hamiltonian structure of Dubrovin{close_quote}s equation of associativity in 2-d topological field theory

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Galvao, C.A.; Nutku, Y.

    1996-12-01

    mA third order Monge-Amp{grave e}re type equation of associativity that Dubrovin has obtained in 2-d topological field theory is formulated in terms of a variational principle subject to second class constraints. Using Dirac{close_quote}s theory of constraints this degenerate Lagrangian system is cast into Hamiltonian form and the Hamiltonian operator is obtained from the Dirac bracket. There is a new type of Kac-Moody algebra that corresponds to this Hamiltonian operator. In particular, it is not a W-algebra. {copyright} {ital 1996 American Institute of Physics.}

  4. Comparative measurements of plasma potential with ball-pen and Langmuir probe in low-temperature magnetized plasma

    NASA Astrophysics Data System (ADS)

    Zanáška, M.; Adámek, J.; Peterka, M.; Kudrna, P.; Tichý, M.

    2015-03-01

    The ball-pen probe (BPP) is used for direct plasma potential measurements in magnetized plasma. The probe can adjust the ratio of the electron and ion saturation currents Isat-/Isat+ to be close to one and therefore its I-V characteristic becomes nearly symmetric. If this is achieved, the floating potential of the BPP is close to the plasma potential. Because of its rather simple construction, it offers an attractive probe for measurements in magnetized plasma. Comparative measurements of plasma potential by BPPs of different dimensions as well as one Langmuir probe (LP) in an argon discharge plasma of a cylindrical magnetron were performed at various experimental conditions. An additional comparison by an emissive probe was also performed. All these types of probes provide similar values of plasma potential in a wide range of plasma parameters. Our results for three different BPP dimensions indicate that the BPP can be operated in a cylindrical magnetron DC argon discharge if the value of the ratio of the magnetic field and neutral gas pressure, B/p, is greater than approximately 10 mT/Pa.

  5. Rotating-unbalanced-mass Devices for Scanning Balloon-borne Experiments, Free-flying Spacecraft, and Space Shuttle/space Station Experiments

    NASA Technical Reports Server (NTRS)

    Polites, Michael E.

    1990-01-01

    A new method is presented for scanning balloon-borne experiments, free-flying spacecraft, and gimballed experiments mounted to the space shuttle or the space station. It uses rotating-unbalanced-mass (RUM) devices for generating circular, line, or raster scan patterns and an auxiliary control system for target acquisition, keeping the scan centered on the target, and producing complementary motion for raster scanning. It is ideal for applications where the only possible way to accomplish the required scan is to physically scan the entire experiment or spacecraft as in x ray and gamma ray experiments. In such cases, this new method should have advantages over prior methods in terms of either power, weight, cost, performance, stability, or a combination of these.

  6. Growth and characterization of a-axis oriented Cr-doped AlN films by DC magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Panda, Padmalochan; Ramaseshan, R.; Krishna, Nanda Gopala; Dash, S.

    2016-05-01

    Wurtzite type Cr-doped AlN thin films were grown on Si (100) substrates using DC reactive magnetron sputtering with a function of N2 concentration (15 to 25%). Evolution of crystal structure of these films was studied by GIXRD where a-axis preferred orientation was observed. The electronic binding energy and concentration of Cr in these films were estimated by X-ray photoemission spectroscopy (XPS). We have observed indentation hardness (HIT) of around 28.2 GPa for a nitrogen concentration of 25%.

  7. Ultra-hard AlMgB14 coatings fabricated by RF magnetron sputtering from a stoichiometric target

    NASA Astrophysics Data System (ADS)

    Grishin, A. M.; Khartsev, S. I.; Böhlmark, J.; Ahlgren, M.

    2015-01-01

    For the first time hard aluminum magnesium boride films were fabricated by RF magnetron sputtering from a single stoichiometric ceramic AlMgB14 target. Optimized processing conditions (substrate temperature, target sputtering power and target-to-substrate distance) enable fabrication of stoichiometric in-depth compositionally homogeneous films with the peak values of nanohardness 88 GPa and Young's modulus 517 GPa at the penetration depth of 26 nm and, respectively, 35 and 275 GPa at 200 nm depth in 2 μm thick film.

  8. A type N radiation field solution with Λ <0 in a curved space-time and closed time-like curves

    NASA Astrophysics Data System (ADS)

    Ahmed, Faizuddin

    2018-05-01

    An anti-de Sitter background four-dimensional type N solution of the Einstein's field equations, is presented. The matter-energy content pure radiation field satisfies the null energy condition (NEC), and the metric is free-from curvature divergence. In addition, the metric admits a non-expanding, non-twisting and shear-free geodesic null congruence which is not covariantly constant. The space-time admits closed time-like curves which appear after a certain instant of time in a causally well-behaved manner. Finally, the physical interpretation of the solution, based on the study of the equation of the geodesics deviation, is analyzed.

  9. Electrochemical characteristics of amorphous carbon nanorod synthesized by radio frequency magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Chang, Hsin-Yueh; Huang, Yung-Jui; Chang, Hsuan-Chen; Su, Wei-Jhih; Shih, Yi-Ting; Chen, John L.; Honda, Shin-ichi; Huang, Ying-Sheng; Lee, Kuei-Yi

    2015-01-01

    Amorphous carbon nanorods (CNRs) were deposited directly using radio frequency magnetron sputtering. The synthesized CNR electrochemical properties were investigated using graphene as the current collector for an electric double layer capacitor. The CNRs were vertically aligned to the graphene to achieve higher specific surface area. The capacitor performance was characterized using electrochemical impedance spectroscopy, cyclic voltammetry, and galvanostatic charge-discharge testing in 1 M KOH electrolyte at 30°C, 40°C, 50°C, and 60°C. The CNR specific capacitance was observed to increase with increasing measurement temperature and could reach up to 830 F/g at 60°C. Even after extensive measurements, the CNR electrode maintained good adhesion to the graphene current collector thereby suggesting electrode material stability.

  10. Particle visualization in high-power impulse magnetron sputtering. II. Absolute density dynamics

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Britun, Nikolay, E-mail: nikolay.britun@umons.ac.be; Palmucci, Maria; Konstantinidis, Stephanos

    2015-04-28

    Time-resolved characterization of an Ar-Ti high-power impulse magnetron sputtering discharge has been performed. The present, second, paper of the study is related to the discharge characterization in terms of the absolute density of species using resonant absorption spectroscopy. The results on the time-resolved density evolution of the neutral and singly-ionized Ti ground state atoms as well as the metastable Ti and Ar atoms during the discharge on- and off-time are presented. Among the others, the questions related to the inversion of population of the Ti energy sublevels, as well as to re-normalization of the two-dimensional density maps in terms ofmore » the absolute density of species, are stressed.« less

  11. Influence of microstructure and surface topography on the electrical conductivity of Cu and Ag thin films obtained by magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Polonyankin, D. A.; Blesman, A. I.; Postnikov, D. V.

    2017-05-01

    Conductive thin films formation by copper and silver magnetron sputtering is one of high technological areas for industrial production of solar energy converters, energy-saving coatings, flat panel displays and touch control panels because of their high electrical and optical properties. Surface roughness and porosity, average grain size, internal stresses, orientation and crystal lattice type, the crystallinity degree are the main physical properties of metal films affecting their electrical resistivity and conductivity. Depending on the film thickness, the dominant conduction mechanism can affect bulk conductivity due to the flow of electron gas, and grain boundary conductivity. The present investigation assesses the effect of microstructure and surface topography on the electrical conductivity of magnetron sputtered Cu and Ag thin films using X-ray diffraction analysis, scanning electron and laser interference microscopy. The highest specific conductivity (78.3 MS m-1 and 84.2 MS m-1, respectively, for copper and silver films at the thickness of 350 nm) were obtained with the minimum values of roughness and grain size as well as a high degree of lattice structuredness.

  12. Improved power control using optimal adjustable coefficients for three-phase photovoltaic inverter under unbalanced grid voltage.

    PubMed

    Wang, Qianggang; Zhou, Niancheng; Lou, Xiaoxuan; Chen, Xu

    2014-01-01

    Unbalanced grid faults will lead to several drawbacks in the output power quality of photovoltaic generation (PV) converters, such as power fluctuation, current amplitude swell, and a large quantity of harmonics. The aim of this paper is to propose a flexible AC current generation method by selecting coefficients to overcome these problems in an optimal way. Three coefficients are brought in to tune the output current reference within the required limits of the power quality (the current harmonic distortion, the AC current peak, the power fluctuation, and the DC voltage fluctuation). Through the optimization algorithm, the coefficients can be determined aiming to generate the minimum integrated amplitudes of the active and reactive power references with the constraints of the inverter current and DC voltage fluctuation. Dead-beat controller is utilized to track the optimal current reference in a short period. The method has been verified in PSCAD/EMTDC software.

  13. Improved Power Control Using Optimal Adjustable Coefficients for Three-Phase Photovoltaic Inverter under Unbalanced Grid Voltage

    PubMed Central

    Wang, Qianggang; Zhou, Niancheng; Lou, Xiaoxuan; Chen, Xu

    2014-01-01

    Unbalanced grid faults will lead to several drawbacks in the output power quality of photovoltaic generation (PV) converters, such as power fluctuation, current amplitude swell, and a large quantity of harmonics. The aim of this paper is to propose a flexible AC current generation method by selecting coefficients to overcome these problems in an optimal way. Three coefficients are brought in to tune the output current reference within the required limits of the power quality (the current harmonic distortion, the AC current peak, the power fluctuation, and the DC voltage fluctuation). Through the optimization algorithm, the coefficients can be determined aiming to generate the minimum integrated amplitudes of the active and reactive power references with the constraints of the inverter current and DC voltage fluctuation. Dead-beat controller is utilized to track the optimal current reference in a short period. The method has been verified in PSCAD/EMTDC software. PMID:25243215

  14. Magnetron Sputtering as a Fabrication Method for a Biodegradable Fe32Mn Alloy

    PubMed Central

    Jurgeleit, Till; Quandt, Eckhard; Zamponi, Christiane

    2017-01-01

    Biodegradable metals are a topic of great interest and Fe-based materials are prominent examples. The research task is to find a suitable compromise between mechanical, corrosion, and magnetic properties. For this purpose, investigations regarding alternative fabrication processes are important. In the present study, magnetron sputtering technology in combination with UV-lithography was used in order to fabricate freestanding, microstructured Fe32Mn films. To adjust the microstructure and crystalline phase composition with respect to the requirements, the foils were post-deposition annealed under a reducing atmosphere. The microstructure and crystalline phase composition were investigated by scanning electron microscopy, energy dispersive X-ray spectroscopy, and X-ray diffraction. Furthermore, for mechanical characterization, uniaxial tensile tests were performed. The in vitro corrosion rates were determined by electrochemical polarization measurements in pseudo-physiological solution. Additionally, the magnetic properties were measured via vibrating sample magnetometry. The foils showed a fine-grained structure and a tensile strength of 712 MPa, which is approximately a factor of two higher compared to the sputtered pure Fe reference material. The yield strength was observed to be even higher than values reported in literature for alloys with similar composition. Against expectations, the corrosion rates were found to be lower in comparison to pure Fe. Since the annealed foils exist in the austenitic, and antiferromagnetic γ-phase, an additional advantage of the FeMn foils is the low magnetic saturation polarization of 0.003 T, compared to Fe with 1.978 T. This value is even lower compared to the SS 316L steel acting as a gold standard for implants, and thus enhances the MRI compatibility of the material. The study demonstrates that magnetron sputtering in combination with UV-lithography is a new concept for the fabrication of already in situ geometrically

  15. Properties of Nanocomposite Nickel-Carbon Films Deposited by Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    Grenadyorov, A. S.; Oskomov, K. V.; Solov'ev, A. A.; Rabotkin, S. V.; Zakharov, A. N.; Semenov, V. A.; Oskirko, V. O.; Yelgin, Yu. I.; Korneva, O. S.

    2017-12-01

    The method of magnetron sputtering was used to produce a-C and a-C:Ni films on substrates of monocrystalline silicon and thermoelectric material of n-type ((Bi2Te3)0.94(Bi2Se3)0.06) and p-type ((Bi2Te3)0.20(Sb2Te3)0.80) conductivity. The authors studied the effect of Ni concentration on specific electric resistance, hardness and adhesion of the produced films. It was demonstrated that specific resistance of a-C films deposited by graphite target sputtering when supplying high bias voltage onto the substrate can be reduced by increasing the share of graphitized carbon. Adding Ni to such films allows additionally reducing their specific resistance. The increase in Ni content is accompanied with the decrease in hardness and adhesion of a-C:Ni films. The acquired values of specific electric resistance and adhesion of a-C:Ni films to thermoelectric materials allow using them as barrier anti-diffusion coatings of thermoelectric modules.

  16. On the road to self-sputtering in high power impulse magnetron sputtering: particle balance and discharge characteristics

    NASA Astrophysics Data System (ADS)

    Huo, Chunqing; Lundin, Daniel; Raadu, Michael A.; Anders, André; Tomas Gudmundsson, Jon; Brenning, Nils

    2014-04-01

    The onset and development of self-sputtering (SS) in a high power impulse magnetron sputtering (HiPIMS) discharge have been studied using a plasma chemical model and a set of experimental data, taken with an aluminum target and argon gas. The model is tailored to duplicate the discharge in which the data are taken. The pulses are long enough to include both an initial transient and a following steady state. The model is used to unravel how the internal discharge physics evolves with pulse power and time, and how it is related to features in the discharge current-voltage-time characteristics such as current densities, maxima, kinks and slopes. The connection between the self-sputter process and the discharge characteristics is quantified and discussed in terms of three parameters: a critical target current density Jcrit based on the maximum refill rate of process (argon) gas above the target, an SS recycling factor ΠSS-recycle, and an approximation \\tilde{\\alpha} of the probabilities of ionization of species that come from the target (both sputtered metal and embedded argon atoms). For low power pulses, discharge voltages UD ⩽ 380 V with peak current densities below ≈ 0.2 A cm-2, the discharge is found to be dominated by process gas sputtering. In these pulses there is an initial current peak in time, associated with partial gas rarefaction, which is followed by a steady-state-like plateau in all parameters similar to direct current magnetron sputtering. In contrast, high power pulses, with UD ⩾ 500 V and peak current densities above JD ≈ 1.6 A cm-2, make a transition to a discharge mode where SS dominates. The transition is found not to be driven by process gas rarefaction which is only about 10% at this time. Maximum gas rarefaction is found later in time and always after the initial peak in the discharge current. With increasing voltage, and pulse power, the discharge can be described as following a route where the role of SS increases in four steps

  17. Anomalous cross-B field transport and spokes in HiPIMS plasma

    NASA Astrophysics Data System (ADS)

    Hecimovic, Ante; Maszl, Christian; Schulz-von der Gathen, Volker; von Keudell, Achim

    2016-09-01

    The rotation of localised ionisation zones, i.e. spokes, in magnetron discharge is investigated as a function of discharge current, ranging from 10 mA (current density 0.5 mA cm-2) to 140 A (7 A cm-2) . The presence of spokes throughout the complete discharge current range indicates that the spokes are an intrinsic property of a magnetron sputtering plasma discharge. Up to discharge currents of several amperes, the spokes rotate in a retrograde ExB direction and beyond the spokes rotate in a ExB direction. In this contribution we present experimental evidence that anomalous diffusion is triggered by the appearance of spokes rotating in the ExB direction. The Hall parameter ωceτc , product of the electron cyclotron frequency and the classical collision time, reduces from Bohm diffusion values (16 and higher) down to the value of 3 as spokes appear, indicating anomalous cross-B field transport. The ion diffusion coefficients calculated from a sideways image of the spoke is six times higher than Bohm diffusion coefficients, which is consistent with the reduction of the Hall parameter.

  18. Influence of Substrate Temperature on Structural, Electrical and Optical Properties of Ito Thin Films Prepared by RF Magnetron Sputtering

    NASA Astrophysics Data System (ADS)

    He, Bo; Zhao, Lei; Xu, Jing; Xing, Huaizhong; Xue, Shaolin; Jiang, Meng

    2013-10-01

    In this paper, we investigated indium-tin-oxide (ITO) thin films on glass substrates deposited by RF magnetron sputtering using ceramic target to find the optimal condition for fabricating optoelectronic devices. The structural, electrical and optical properties of the ITO films prepared at various substrate temperatures were investigated. The results indicate the grain size increases with substrate temperature increases. As the substrate temperature grew up, the resistivity of ITO films greatly decreased. The ITO film possesses high quality in terms of electrode functions, when substrate temperature is 480°C. The resistivity is as low as 9.42 × 10-5 Ω•cm, while the carrier concentration and mobility are as high as 3.461 × 1021 atom/cm3 and 19.1 cm2/Vṡs, respectively. The average transmittance of the film is about 95% in the visible region. The novel ITO/np-Silicon frame, which prepared by RF magnetron sputtering at 480°C substrate temperature, can be used not only for low-cost solar cell, but also for high quantum efficiency of UV and visible lights enhanced photodetector for various applications.

  19. Distribution of Fe atom density in a dc magnetron sputtering plasma source measured by laser-induced fluorescence imaging spectroscopy

    NASA Astrophysics Data System (ADS)

    Shibagaki, K.; Nafarizal, N.; Sasaki, K.; Toyoda, H.; Iwata, S.; Kato, T.; Tsunashima, S.; Sugai, H.

    2003-10-01

    Magnetron sputtering discharge is widely used as an efficient method for thin film fabrication. In order to achieve the optimized fabrication, understanding of the kinetics in plasmas is essential. In the present work, we measured the density distribution of sputtered Fe atoms using laser-induced fluorescence imaging spectroscopy. A dc magnetron plasma source with a Fe target was used. An area of 20 × 2 mm in front of the target was irradiated by a tunable laser beam having a planar shape. The picture of laser-induced fluorescence on the laser beam was taken using an ICCD camera. In this way, we obtained the two-dimensional image of the Fe atom density. As a result, it has been found that the Fe atom density observed at a distance of several centimeters from the target is higher than that adjacent to the target, when the Ar gas pressure was relatively high. It is suggested from this result that some gas-phase production processes of Fe atoms are available in the plasma. This work has been performed under the 21st Century COE Program by the Ministry of Education, Culture, Sports, Science and Technology in Japan.

  20. One-step aluminium-assisted crystallization of Ge epitaxy on Si by magnetron sputtering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Liu, Ziheng, E-mail: ziheng.liu@unsw.edu.au; Hao, Xiaojing; Ho-Baillie, Anita

    In this work, one-step aluminium-assisted crystallization of Ge on Si is achieved via magnetron sputtering by applying an in-situ low temperature (50 °C to 150 °C) heat treatment in between Al and Ge depositions. The effect of heat treatment on film properties and the growth mechanism of Ge epitaxy on Si are studied via X-ray diffraction, Raman and transmission electron microscopy analyses. Compared with the conventional two-step process, the one-step aluminium-assisted crystallization requires much lower thermal budget and results in pure Ge epitaxial layer, which may be suitable for use as a virtual substrate for the fabrication of III-V solar cells.

  1. Particle visualization in high-power impulse magnetron sputtering. I. 2D density mapping

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Britun, Nikolay, E-mail: nikolay.britun@umons.ac.be; Palmucci, Maria; Konstantinidis, Stephanos

    2015-04-28

    Time-resolved characterization of an Ar-Ti high-power impulse magnetron sputtering discharge has been performed. This paper deals with two-dimensional density mapping in the discharge volume obtained by laser-induced fluorescence imaging. The time-resolved density evolution of Ti neutrals, singly ionized Ti atoms (Ti{sup +}), and Ar metastable atoms (Ar{sup met}) in the area above the sputtered cathode is mapped for the first time in this type of discharges. The energetic characteristics of the discharge species are additionally studied by Doppler-shift laser-induced fluorescence imaging. The questions related to the propagation of both the neutral and ionized discharge particles, as well as to theirmore » spatial density distributions, are discussed.« less

  2. Growth and characterization of a-axis oriented Cr-doped AlN films by DC magnetron sputtering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Panda, Padmalochan; Ramaseshan, R., E-mail: seshan@igcar.gov.in; Dash, S.

    2016-05-23

    Wurtzite type Cr-doped AlN thin films were grown on Si (100) substrates using DC reactive magnetron sputtering with a function of N{sub 2} concentration (15 to 25%). Evolution of crystal structure of these films was studied by GIXRD where a-axis preferred orientation was observed. The electronic binding energy and concentration of Cr in these films were estimated by X-ray photoemission spectroscopy (XPS). We have observed indentation hardness (H{sub IT}) of around 28.2 GPa for a nitrogen concentration of 25%.

  3. Measured density of copper atoms in the ground and metastable states in argon magnetron discharge correlated with the deposition rate

    NASA Astrophysics Data System (ADS)

    Naghshara, H.; Sobhanian, S.; Khorram, S.; Sadeghi, N.

    2011-01-01

    In a dc-magnetron discharge with argon feed gas, densities of copper atoms in the ground state Cu(2S1/2) and metastable state Cu*(2D5/2) were measured by the resonance absorption technique, using a commercial hollow cathode lamp as light source. The operating conditions were 0.3-14 µbar argon pressure and 10-200 W magnetron discharge power. The deposition rate of copper in a substrate positioned at 18 cm from the target was also measured with a quartz microbalance. The gas temperature, in the range 300-380 K, was deduced from the emission spectral profile of N2(C 3Πu - B 3Πg) 0-0 band at 337 nm when trace of nitrogen was added to the argon feed gas. The isotope-shifts and hyperfine structures of electronic states of Cu have been taken into account to deduce the emission and absorption line profiles, and hence for the determination of atoms' densities from the measured absorption rates. To prevent error in the evaluation of Cu density, attributed to the line profile distortion by auto-absorption inside the lamp, the lamp current was limited to 5 mA. Density of Cu(2S1/2) atoms and deposition rate both increased with the enhanced magnetron discharge power. But at fixed power, the copper density augmented with argon pressure whereas the deposition rate followed the opposite trend. Whatever the gas pressure, the density of Cu*(2D5/2) metastable atoms remained below the detection limit of 1 × 1010 cm-3 for magnetron discharge powers below 50 W and hence increased much more rapidly than the density of Cu(2S1/2) atoms, over passing this later at some discharge power, whose value decreases with increasing argon pressure. This behaviour is believed to result from the enhancement of plasma density with increasing discharge power and argon pressure, which would increase the excitation rate of copper into metastable states. At fixed pressure, the deposition rate followed the same trend as the total density of copper atoms in the ground and metastable states. Two important

  4. The Tribological Performance of Surface Treated Ti6A14V as Sliding Against Si3N4 Ball and 316L Stainless Steel Cylinder

    NASA Astrophysics Data System (ADS)

    Kao, W. H.; Su, Y. L.; Horng, J. H.; Huang, H. C.

    2016-12-01

    Closed field unbalanced magnetron sputtering was used to deposit diamond-like carbon (Ti-C:H) coatings on Ti6Al4V alloy and gas nitrided Ti6Al4V alloy. Four different specimens were prepared, namely untreated Ti6Al4V alloy (Ti6Al4V), gas nitrided Ti6Al4V alloy (N-Ti6Al4V), Ti-C:H-coated Ti6Al4V alloy (Ti-C:H/Ti6Al4V) and Ti-C:H-coated gas nitrided Ti6Al4V alloy (Ti-C:H/N-Ti6Al4V). The tribological properties of the four specimens were evaluated using a reciprocating wear tester sliding against a Si3N4 ball (point contact mode) and 316L stainless steel cylinder (line contact mode). The wear tests were performed in a 0.89 wt.% NaCl solution. The results showed that the nitriding treatment increased the surface roughness and hardness of the Ti6Al4V alloy and improved the wear resistance as a result. In addition, the Ti-C:H coating also improved the tribological performance of Ti6Al4V. For example, compared to the untreated Ti6Al4V sample, the Ti-C:H coating reduced the wear depth and friction coefficient by 340 times and 10 times, respectively, in the point contact wear mode, and 151 times and 9 times, respectively, in the line contact wear mode. It is thus inferred that diamond-like carbon coatings are of significant benefit in extending the service life of artificial biomedical implants.

  5. Inheritance of a Balanced t(12;20)(q24.33;p12.2) and Unbalanced der(13)t(7;13)(p21.3;q33.2) from a Maternally Derived Double Balanced Translocation Carrier.

    PubMed

    Peterson, Jess F; Geddes, Gabrielle C; Basel, Donald G; Schippman, Dana; Grignon, John W; vanTuinen, Peter; Kappes, Ulrike P

    2018-03-01

    We report a 4-month-old male proband with a history of prominent forehead, hypertelorism, ear abnormalities, micrognathia, hypospadias, and multiple cardiac abnormalities. Initial microarray analysis detected a concurrent 7p21.3-p22.3 duplication and 13q33.2-q34 deletion indicating an unbalanced rearrangement. However, subsequent conventional cytogenetic studies only revealed what appeared to be a balanced t(12;20)(q24.33;p12.2). Fluorescence in situ hybridization (FISH) using chromosome-specific subtelomere probes confirmed the presence of an unbalanced der(13)t(7;13)(p21.3;q33.2) and balanced t(12;20)(q24.33;p12.2), both of maternal origin. In addition to our unique clinical findings, this case highlights the benefits and limitations of both conventional cytogenetic studies and microarray analysis and how FISH complements each methodology.

  6. Functional Dependence for Calculation of Additional Real-Power Losses in a Double-Wound Supply Transformer Caused by Unbalanced Active Inductive Load in a Star Connection with an Insulated Neutral

    ERIC Educational Resources Information Center

    Kostinskiy, Sergey S.; Troitskiy, Anatoly I.

    2016-01-01

    This article deals with the problem of calculating the additional real-power losses in double-wound supply transformers with voltage class 6 (10)/0,4 kV, caused by unbalanced active inductive load connected in a star connection with an insulated neutral. When solving the problem, authors used the theory of electric circuits, method of balanced…

  7. RP and RQA Analysis for Floating Potential Fluctuations in a DC Magnetron Sputtering Plasma

    NASA Astrophysics Data System (ADS)

    Sabavath, Gopikishan; Banerjee, I.; Mahapatra, S. K.

    2016-04-01

    The nonlinear dynamics of a direct current magnetron sputtering plasma is visualized using recurrence plot (RP) technique. RP comprises the recurrence quantification analysis (RQA) which is an efficient method to observe critical regime transitions in dynamics. Further, RQA provides insight information about the system’s behavior. We observed the floating potential fluctuations of the plasma as a function of discharge voltage by using Langmuir probe. The system exhibits quasi-periodic-chaotic-quasi-periodic-chaotic transitions. These transitions are quantified from determinism, Lmax, and entropy of RQA. Statistical investigations like kurtosis and skewness also studied for these transitions which are in well agreement with RQA results.

  8. As(III) Removal from Drinking Water by Carbon Nanotube Membranes with Magnetron-Sputtered Copper: Performance and Mechanisms.

    PubMed

    Luan, Hongyan; Zhang, Quan; Cheng, Guo-An; Huang, Haiou

    2018-06-20

    Current approaches for functionalizing carbon nanotubes (CNTs) often utilize harsh chemical conditions, and the resulting harmful wastes can cause various environmental and health concerns. In this study, magnetron sputtering technique is facilely employed to functionalize CNT membranes by depositing Cu onto premade CNT membranes without using any chemical treatment. A comparative evaluation of the substrate polymeric membrane (mixed cellulose ester (MCE)), MCE sputtered with copper (Cu/MCE), the pristine CNT membrane (CNT), and CNT membrane sputtered with Cu (Cu/CNT) shows that Cu/CNT possesses mechanically stable structures and similar membrane permeability as MCE. More importantly, Cu/CNT outperforms other membranes with high As(III) removal efficiency of above 90%, as compared to less than 10% by MCE and CNT, and 75% by Cu/MCE from water. The performance of Cu/CNT membranes for As(III) removal is also investigated as a function of ionic strength, sputtering time, co-existing ions, solution pH, and the reusability. Further characterizations of As speciation in the filtrate and on Cu/CNT reveal that arsenite removal by Cu/CNT possibly began with Cu-catalyzed oxidation of arsenite to arsenate, followed by adsorptive filtration of arsenate by the membrane. Overall, this study demonstrates that magnetron sputtering is a promising greener technology for the productions of metal-CNT composite membranes for environmental applications.

  9. UV-Enhanced Ethanol Sensing Properties of RF Magnetron-Sputtered ZnO Film.

    PubMed

    Huang, Jinyu; Du, Yu; Wang, Quan; Zhang, Hao; Geng, Youfu; Li, Xuejin; Tian, Xiaoqing

    2017-12-26

    ZnO film was deposited by the magnetron sputtering method. The thickness of ZnO film is approximately 2 μm. The influence of UV light illumination on C₂H₅OH sensing properties of ZnO film was investigated. Gas sensing results revealed that the UV-illuminated ZnO film displays excellent C₂H₅OH characteristics in terms of high sensitivity, excellent selectivity, rapid response/recovery, and low detection limit down to 0.1 ppm. The excellent sensing performance of the sensor with UV activation could be attributed to the photocatalytic oxidation of ethanol on the surface of the ZnO film, the planar film structure with high utilizing efficiency of UV light, high electron mobility, and a good surface/volume ratio of of ZnO film with a relatively rough and porous surface.

  10. On Both Spatial And Velocity Distribution Of Sputtered Particles In Magnetron Discharge

    NASA Astrophysics Data System (ADS)

    Vitelaru, C.; Pohoata, V.; Tiron, V.; Costin, C.; Popa, G.

    2012-12-01

    The kinetics of the sputtered atoms from the metallic target as well as the time-space distribution of the argon metastable atoms have been investigated for DC and high power pulse magnetron discharge by means of Tunable Diode - Laser Absorption Spectroscopy (TD-LAS) and Tunable Diode - Laser Induced Fluorescence (TD-LIF). The discharge was operated in argon (5-30 mTorr) with two different targets, tungsten and aluminum, for pulses of 1 to 20 μs, at frequencies of 0.2 to 1 kHz. Peak current intensity of ~100 A has been attained at cathode peak voltage of ~1 kV. The mean velocity distribution functions and particle fluxes of the sputtered metal atoms, in parallel and perpendicular direction to the target, have been obtained and compared for DC and pulse mode.

  11. Synthesis and properties of nanocrystalline copper indium oxide thin films deposited by Rf magnetron sputtering.

    PubMed

    Singh, Mandeep; Singh, V N; Mehta, B R

    2008-08-01

    Nanocrystalline copper indium oxide (CuInO2) thin films with particle size ranging from 25 nm to 71 nm have been synthesized from a composite target using reactive Rf magnetron sputtering technique. X-ray photoelectron spectroscopy (XPS) combined with glancing angle X-ray diffraction (GAXRD) analysis confirmed the presence of delafossite CuInO2 phase in these films. The optical absorption studies show the presence of two direct band gaps at 3.3 and 4.3 eV, respectively. The resistance versus temperature measurements show thermally activated hopping with activation energy of 0.84 eV to be the conduction mechanism.

  12. The role of growth form and correlated traits in competitive ranking of six perennial ruderal plant species grown in unbalanced mixtures

    NASA Astrophysics Data System (ADS)

    Dietz, Hansjörg; Steinlein, Thomas; Ullmann, Isolde

    1998-02-01

    The competitive abilities of six perennial ruderal plants of three different growth forms were compared via yield measures using an additive diallel experimental design with unbalanced mixtures (9:3 or 3:9 plants per pot, respectively). Thus, in a given mixture species A was grown in two configurations: three individuals in centre position of the pot together with nine plants of species B in border position and vice versa. Effect competitive abilities as well as response competitive abilities of the species were significantly related to canopy height and plant biomass. The species with lower rosette growth form and smaller biomasses were weaker competitors than the species possessing elevated canopies along with higher biomasses, whereas total leaf area was not significantly correlated with competitive ability between species. Species differences in competitive ability were stronger between the plants grown in the central position than between those grown in the border position. Furthermore, interactions between species-specific traits and configuration could be observed, indicating the importance of species proportions and arrangement patterns for evaluation of competitive outcome in the field. The degree of complete transitivity of the competitive network of the six ruderal species, which was significantly higher than expected under the null model in our experimental design, also seemed to depend on species proportions in mixture. Shifts in root:shoot ratio of the centre plants when faced with competition by the border plants were in the direction of higher shoot allocation for the weak competitors with rosette growth form irrespective of the neighbour species, except for Bunias orientalis, which showed a more plastic response. The stronger competitors showed higher root allocation ( Urtica dioica) or were hardly affected at all. Consistent with the results of our experiment, the weaker competitors occur at rather frequently disturbed and therefore transient

  13. Composition-control of magnetron-sputter-deposited (BaxSr1-x)Ti1+yO3+z thin films for voltage tunable devices

    NASA Astrophysics Data System (ADS)

    Im, Jaemo; Auciello, O.; Baumann, P. K.; Streiffer, S. K.; Kaufman, D. Y.; Krauss, A. R.

    2000-01-01

    Precise control of composition and microstructure is critical for the production of (BaxSr1-x)Ti1+yO3+z (BST) dielectric thin films with the large dependence of permittivity on electric field, low losses, and high electrical breakdown fields that are required for successful integration of BST into tunable high-frequency devices. Here, we present results on composition-microstructure-electrical property relationships for polycrystalline BST films produced by magnetron-sputter deposition, that are appropriate for microwave and millimeter-wave applications such as varactors and frequency triplers. Films with controlled compositions were grown from a stoichiometric Ba0.5Sr0.5TiO3 target by control of the background processing gas pressure. It was determined that the (Ba+Sr)/Ti ratios of these BST films could be adjusted from 0.73 to 0.98 by changing the total (Ar+O2) process pressure, while the O2/Ar ratio did not strongly affect the metal ion composition. Film crystalline structure and dielectric properties as a function of the (Ba+Sr)/Ti ratio are discussed. Optimized BST films yielded capacitors with low dielectric losses (0.0047), among the best reported for sputtered BST, while still maintaining tunabilities suitable for device applications.

  14. Evaporation-assisted high-power impulse magnetron sputtering: The deposition of tungsten oxide as a case study

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Hemberg, Axel; Dauchot, Jean-Pierre; Snyders, Rony

    2012-07-15

    The deposition rate during the synthesis of tungsten trioxide thin films by reactive high-power impulse magnetron sputtering (HiPIMS) of a tungsten target increases, above the dc threshold, as a result of the appropriate combination of the target voltage, the pulse duration, and the amount of oxygen in the reactive atmosphere. This behavior is likely to be caused by the evaporation of the low melting point tungsten trioxide layer covering the metallic target in such working conditions. The HiPIMS process is therefore assisted by thermal evaporation of the target material.

  15. Formation of the N-MWCNT/TiOx nanocomposite structure using magnetron method for gas sensing application

    NASA Astrophysics Data System (ADS)

    Bolotov, V. V.; Kan, V. E.; Knyazev, E. V.; Davletkildeev, N. A.; Nesov, S. N.; Ponomareva, I. V.; Sokolov, D. V.; Korusenko, P. M.

    2017-08-01

    The nanocomposite structures N-MWCNT/TiOx based on nitrogen-doped multi-walled carbon nanotubes (N-MWCNT) have been synthesized using magnetron sputtering. The morphology, structure, composition and also the electro-physical properties of the nanocomposite structures have been investigated. The changes of the Fermi level position and the electrical conductivity of N-MWCNT and N-MWCNT/TiOx structures at the adsorption of the oxidizing and reducing gas molecules have been studied. The obtained nanocomposite structures demonstrate the wide perspectives as the sensing media for gas micro- and nanosensors.

  16. Coating multilayer material with improved tribological properties obtained by magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Mateescu, A. O.; Mateescu, G.; Balasoiu, M.; Pompilian, G. O.; Lungu, M.

    2017-02-01

    This work is based on the Patent no. RO 128094 B1, granted by the Romanian State Office for Inventions and Trademarks. The goal of the work is to obtain for investigations tribological coatings with multilayer structure with improved tribological properties, deposited by magnetron sputtering process from three materials (sputtering targets). Starting from compound chemical materials (TiC, TiB2 and WC), as sputtering targets, by deposition in argon atmosphere on polished stainless steel, we have obtained, based on the claims of the above patent, thin films of multilayer design with promising results regarding their hardness, elastic modulus, adherence, coefficient of friction and wear resistance. The sputtering process took place in a special sequence in order to ensure better tribological properties to the coating, comparing to those of the individual component materials. The tribological properties, such as the coefficient of friction, are evaluated using the tribometer test.

  17. Cyclopia and cebocephaly in two newborn infants with unbalanced segregation of a familial translocation rcp (1;7)(q32;q34).

    PubMed

    Schinzel, A

    1984-05-01

    This is a report of a family with a balanced reciprocal translocation, rcp (1;7)(q32;q34). Among pregnancies from translocation carriers, there were several miscarriages, and two unbalanced offspring with dup(1q32----qter) and del (7q34----qter) who died perinatally. One was a male cyclops with additional brain malformations and hydronephrosis, the other was a cebocephalic female with multiple additional malformations of heart, kidneys, and skeleton. In both pregnancies, the brain and renal anomalies were detected prenatally by ultrasound, in the cyclops during the 32nd and in the cebocephalic fetus during the 28th week of gestation.

  18. Comparison of potential field solutions for Carrington Rotation 2144

    NASA Astrophysics Data System (ADS)

    Hayashi, Keiji; Yang, Shangbin; Deng, Yuagyong

    2016-02-01

    We examined differences among the coronal magnetic field structures derived with the potential field source surface (PFSS) model for Carrington Rotation 2144, from 21 November to 19 December 2013. We used the synoptic maps of solar photospheric magnetic field from four observatories, the Huairou Solar Observing Station (HSOS), Global Oscillation Network Group (GONG), Helioseismic Magnetic Imager (HMI), and Wilcox Solar Observatory (WSO). We tested two smoothing methods, Gaussian and boxcar averaging, and correction of unbalanced net magnetic flux. The solutions of three-dimensional coronal magnetic field are significantly different each other. An open-field region derived with HSOS data agrees best with the corresponding coronal hole observed by Solar Dynamics Observatories/Atmospheric Imaging Assembly, while HMI data yielded best agreements with the near-Earth OMNI database. The GONG data overall gave agreements as good as the HMI. The PFSS calculations using WSO data were least sensitive to the choices we examined in this work. Differences in PFSS solutions using different choices and parameters in smoothing imply that the photospheric magnetic field distributions with size of several degrees at midlatitude and low-latitude regions can be decisive, at least, in the examined period. To better determine the global solar corona, therefore, further evaluation of influences from compact bipolar magnetic field is needed.

  19. Full-Process Computer Model of Magnetron Sputter, Part I: Test Existing State-of-Art Components

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Walton, C C; Gilmer, G H; Wemhoff, A P

    2007-09-26

    This work is part of a larger project to develop a modeling capability for magnetron sputter deposition. The process is divided into four steps: plasma transport, target sputter, neutral gas and sputtered atom transport, and film growth, shown schematically in Fig. 1. Each of these is simulated separately in this Part 1 of the project, which is jointly funded between CMLS and Engineering. The Engineering portion is the plasma modeling, in step 1. The plasma modeling was performed using the Object-Oriented Particle-In-Cell code (OOPIC) from UC Berkeley [1]. Figure 2 shows the electron density in the simulated region, using magneticmore » field strength input from experiments by Bohlmark [2], where a scale of 1% is used. Figures 3 and 4 depict the magnetic field components that were generated using two-dimensional linear interpolation of Bohlmark's experimental data. The goal of the overall modeling tool is to understand, and later predict, relationships between parameters of film deposition we can change (such as gas pressure, gun voltage, and target-substrate distance) and key properties of the results (such as film stress, density, and stoichiometry.) The simulation must use existing codes, either open-source or low-cost, not develop new codes. In part 1 (FY07) we identified and tested the best available code for each process step, then determined if it can cover the size and time scales we need in reasonable computation times. We also had to determine if the process steps are sufficiently decoupled that they can be treated separately, and identify any research-level issues preventing practical use of these codes. Part 2 will consider whether the codes can be (or need to be) made to talk to each other and integrated into a whole.« less

  20. Inflation in a closed universe

    NASA Astrophysics Data System (ADS)

    Ratra, Bharat

    2017-11-01

    To derive a power spectrum for energy density inhomogeneities in a closed universe, we study a spatially-closed inflation-modified hot big bang model whose evolutionary history is divided into three epochs: an early slowly-rolling scalar field inflation epoch and the usual radiation and nonrelativistic matter epochs. (For our purposes it is not necessary to consider a final dark energy dominated epoch.) We derive general solutions of the relativistic linear perturbation equations in each epoch. The constants of integration in the inflation epoch solutions are determined from de Sitter invariant quantum-mechanical initial conditions in the Lorentzian section of the inflating closed de Sitter space derived from Hawking's prescription that the quantum state of the universe only include field configurations that are regular on the Euclidean (de Sitter) sphere section. The constants of integration in the radiation and matter epoch solutions are determined from joining conditions derived by requiring that the linear perturbation equations remain nonsingular at the transitions between epochs. The matter epoch power spectrum of gauge-invariant energy density inhomogeneities is not a power law, and depends on spatial wave number in the way expected for a generalization to the closed model of the standard flat-space scale-invariant power spectrum. The power spectrum we derive appears to differ from a number of other closed inflation model power spectra derived assuming different (presumably non de Sitter invariant) initial conditions.

  1. High sensitivity electric field monitoring system for control of field-induced CD degradation in reticles (EFM)

    NASA Astrophysics Data System (ADS)

    Sebald, Thomas; Rider, Gavin

    2009-04-01

    It has recently been reported [1] that production reticles are subject to progressive CD degradation during use and intense study is under way to try and identify the causes of it. One damage mechanism which has already been identified and quantified [2] is electric field induced migration of chrome (EFM). This can be caused by electric fields that are more than 100x weaker than those that cause ESD. Such low level electric fields can be experienced by a reticle during normal handling and processing steps, as well as coming from external sources during transportation and storage. The field strength of concern is lower than most electrostatic field meters are designed to measure and it can be difficult or impossible to measure such fields inside the cramped environment of equipment. To measure this risk a new sensor device ("E-Reticle") has been developed having the same materials of construction and form factor as a standard chrome-on-quartz reticle. It allows the electric field that a reticle would experience during normal use and handling to be measured and recorded. Results from testing of this device in a semiconductor production facility are reported, showing that certain processes like reticle washing are inherently hazardous. It also enables identification of problems with electrostatic protection measures inside equipment, such as unbalanced ionizers or poor load port grounding. The device is shown to be capable of recording electric fields in the reticle handling environment that are below the recommended maximum that is being proposed for the 2009 ITRS guidelines.

  2. Discharge Characteristic of VHF-DC Superimposed Magnetron Sputtering System

    NASA Astrophysics Data System (ADS)

    Toyoda, Hirotaka; Fukuoka, Yushi; Fukui, Takashi; Takada, Noriharu; Sasai, Kensuke

    2014-10-01

    Magnetron plasmas are one of the most important tools for sputter deposition of thin films. However, energetic particles from the sputtered target such as backscattered rare gas atoms or oxygen negative ions from oxide targets sometimes induce physical and chemical damages as well as surface roughening to the deposited film surface during the sputtering processes. To suppress kinetic energy of such particles, superposition of RF or VHF power to the DC power has been investigated. In this study, influence of the VHF power superposition on the DC target voltage, which is important factor to determine kinetic energy of high energy particles, is investigated. In the study, 40 MHz VHF power was superimposed to an ITO target and decrease in the target DC voltage was measured as well as deposited film deposition properties such as deposition rate or electrical conductivity. From systematic measurement of the target voltage, it was revealed that the target voltage can be determined by a very simple parameter, i.e., a ratio of VHF power to the total input power (DC and VHF powers) in spite of the DC discharge current. Part of this work was supported by ASTEP, JST.

  3. Combinatorial study of low-refractive Mg-F-Si-O nano-composites deposited by magnetron co-sputtering from compound targets

    NASA Astrophysics Data System (ADS)

    Mertin, Stefan; Länzlinger, Tony; Sandu, Cosmin S.; Scartezzini, Jean-Louis; Muralt, Paul

    2018-03-01

    Deposition of nano-composite Mg-F-Si-O films on optical grade silica glass was studied employing RF magnetron co-sputtering from magnesium fluoride (MgF2) and fused silica (SiO2) targets. The aim was to obtain a stable and reliable sputtering process for optical coatings exhibiting a refractive index lower than the one of quartz glass (1.46 at 550 nm) without adding gaseous fluorine to the deposition process. The two magnetrons were installed in a confocal way at 45° off-axis with respect to a static substrate, thus creating a lateral gradient in the thin-film composition. The deposited Mg-F-Si-O coatings were structurally analysed by electron dispersive X-ray spectroscopy (EDX), transmission electron microscopy (TEM) and scanning electron microscopy (SEM). The obtained films consist of MgF2 nanocrystals embedded in a SiO2-rich amorphous matrix. Spectroscopic ellipsometry and spectrophotometry measurements showed that they are highly transparent exhibiting a very-low extinction coefficient k and a refractive index n in the desired range between the one of MgF2 (1.38) and SiO2 (1.46). Films with n = 1.424 and 1.435 at 550 nm were accomplished with absorption below the detection threshold.

  4. Effect of unbalanced diets on the long-term metabolism of a toxicant. 1. Lead in rats: preliminary note.

    PubMed

    Baldini, M; Coni, E; Mantovani, A; Stacchini, A; Zanasi, F

    1989-01-01

    The aim of this study was the evaluation of the effect of dietary imbalances on absorption and distribution of lead in the female Sprague-Dawley rat. In this note preliminary results on the relationship between blood concentrations of lead and unbalanced diets are presented. Hyperproteic, hyperglycidic, hyperlipidic and balanced diets were prepared, and most of them included 15 mg/kg lead. Blood samples were collected at day 0, 21, 36, and 95 of the diets and analyzed by anodic stripping voltammetry (ASV). Lead uptake as a function of feed consumption was found to decrease in the order: balanced, hyperproteic and hyperglycidic, hyperlipidic diet. On the other hand lead blood levels were as follows (decreasing order): hyperlipidic, hyperproteic, hyperglycidic, balanced. Further research is being carried out on the influences of dietary imbalances on whole-body distribution of lead.

  5. Structural and morphological properties of ITO thin films grown by magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Ghorannevis, Z.; Akbarnejad, E.; Ghoranneviss, M.

    2015-10-01

    Physical properties of transparent and conducting indium tin oxide (ITO) thin films grown by radiofrequency (RF) magnetron sputtering are studied systematically by changing deposition time. The X-ray diffraction (XRD) data indicate polycrystalline thin films with grain orientations predominantly along the (2 2 2) and (4 0 0) directions. From atomic force microscopy (AFM) it is found that by increasing the deposition time, the roughness of the film increases. Scanning electron microscopy (SEM) images show a network of a high-porosity interconnected nanoparticles, which approximately have a pore size ranging between 20 and 30 nm. Optical measurements suggest an average transmission of 80 % for the ITO films. Sheet resistances are investigated using four-point probes, which imply that by increasing the film thickness the resistivities of the films decrease to 2.43 × 10-5 Ω cm.

  6. Electrochemical and microstructural characterization of magnetron-sputtered ATO thin films as Li–ion storage materials

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Ouyang, Pan; Zhang, Hong; Chen, Wenhao

    2015-01-15

    Highlights: • Nano-structured ATO thin films prepared by RF magnetron sputtering at 25 °C, 100 °C and 200 °C, respectively. • ATO thin films show a high reversible capacity and high rate performance. • Electrochemical reaction mechanism of the ATO thin film was revealed by transmission electron microscopy. - Abstract: Sb-doped SnO{sub 2} (ATO) nanostructured thin films were prepared by using radio frequency magnetron sputtering at the substrate temperatures of 25 °C, 100 °C and 200 °C, respectively. All the ATO thin films have the similar redox characteristics in the cyclic voltammetry measurements. The ATO thin film sputtered at 200more » °C shows the lowest charge transfer resistance and best electrochemical performance, and has a high reversible capacity of 679 mA h g{sup −1} at 100 mA g{sup −1} after 200 charge–discharge cycles and high rate performance of 483 mA h g{sup −1} at 800 mA g{sup −1}. The electrochemical mechanisms were investigated by analyzing the phase evolution of the ATO electrodes that had been electrochemically induced at various stages. The results reveal that the ATO underwent reversible lithiation/delithiation processes during the electrochemical cycles, i.e., the SnO{sub 2} reacted with Li{sup +} to produce metallic Sn and followed by the formation of the Li{sub x}Sn alloys during discharge process, and then Li{sub x}Sn alloys de-alloyed, Sn reacted with Li{sub 2}O, and even partially formed SnO{sub 2} during charge process.« less

  7. DC Magnetron Sputtered IZTO Thin Films for Organic Photovoltaic Application.

    PubMed

    Lee, Hye Ji; Noviyana, Imas; Putri, Maryane; Koo, Chang Young; Lee, Jung-A; Kim, Jeong-Joo; Jeong, Youngjun; Lee, Youngu; Lee, Hee Young

    2018-02-01

    IZTO20 (In0.6Zn0.2Sn0.2O1.5) ceramic target was prepared from oxide mixture of In2O3, ZnO, and SnO2 powders. IZTO20 thin films were then deposited onto glass substrate at 400 °C by DC magnetron sputtering. The average optical transmittance determined by ultraviolet-visible spectroscopy was higher than 85% for all films. The minimum resistivity of the annealed IZTO20 thin film was approximately 6.1×10-4 Ω·cm, which tended to increase with decreasing indium content. Substrate heating and annealing were found to be important parameters affecting the electrical and optical properties. An organic photovoltaic (OPV) cell was fabricated using the IZTO20 film deposited under the optimized condition as an anode electrode and the efficiency of up to 80% compared to that of a similar OPV cell using ITO film was observed. Reduction of surface roughness and electrical resistivity through annealing treatment was found to contribute to the improved efficiency of the OPV cell.

  8. High-altitude closed magnetic loops at Mars observed by MAVEN

    NASA Astrophysics Data System (ADS)

    Xu, Shaosui; Mitchell, David; Luhmann, Janet; Ma, Yingjuan; Fang, Xiaohua; Harada, Yuki; Hara, Takuya; Brain, David; Webber, Tristan; Mazelle, Christian; DiBraccio, Gina A.

    2017-10-01

    With electron and magnetic field data obtained by the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft, we have identified closed magnetic field lines, with both footpoints embedded in the dayside ionosphere, extending up to 6200 km altitude (2.8 $R_m$) into the Martian tail. This topology is deduced from photoelectrons produced in the dayside ionosphere being observed in both parallel and anti-parallel directions along the magnetic field line. At perpendicular pitch angles, cases with either solar wind electrons or photoelectrons have been found, indicative of different formation mechanisms of these closed loops. These large closed loops are predicted by MHD simulations. The case with field-aligned photoelectrons mixed with perpendicular solar wind electrons is likely to be associated with reconnection, while the case with photoelectrons in all directions are probably due to closed field lines being pulled back down tail. We have developed an automated algorithm for distinguishing photoelectrons from solar wind electrons in pitch angle resolved energy spectra. This allows us to systematically analyze the MAVEN database and map the spatial distribution and occurrence rate of these closed magnetic loops, ranging from a few percent to a few tens percent outside of the optical shadow and less than one percent within the wake. These observations can be used to investigate the general magnetic topology in the tail, which is relevant to ion escape, reconnection, and flux ropes.

  9. Three-Dimensional, Fibrous Lithium Iron Phosphate Structures Deposited by Magnetron Sputtering.

    PubMed

    Bünting, Aiko; Uhlenbruck, Sven; Sebold, Doris; Buchkremer, H P; Vaßen, R

    2015-10-14

    Crystalline, three-dimensional (3D) structured lithium iron phosphate (LiFePO4) thin films with additional carbon are fabricated by a radio frequency (RF) magnetron-sputtering process in a single step. The 3D structured thin films are obtained at deposition temperatures of 600 °C and deposition times longer than 60 min by using a conventional sputtering setup. In contrast to glancing angle deposition (GLAD) techniques, no tilting of the substrate is required. Thin films are characterized by X-ray diffraction (XRD), Raman spectrospcopy, scanning electron microscopy (SEM), cyclic voltammetry (CV), and galvanostatic charging and discharging. The structured LiFePO4+C thin films consist of fibers that grow perpendicular to the substrate surface. The fibers have diameters up to 500 nm and crystallize in the desired olivine structure. The 3D structured thin films have superior electrochemical properties compared with dense two-dimensional (2D) LiFePO4 thin films and are, hence, very promising for application in 3D microbatteries.

  10. A mechanism for the dynamo terms to sustain closed-flux current, including helicity balance, by driving current which crosses the magnetic field

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jarboe, T. R.; Nelson, B. A.; Sutherland, D. A.

    2015-07-15

    An analysis of imposed dynamo current drive (IDCD) [T.R. Jarboe et al., Nucl. Fusion 52 083017 (2012)] reveals: (a) current drive on closed flux surfaces seems possible without relaxation, reconnection, or other flux-surface-breaking large events; (b) the scale size of the key physics may be smaller than is often computationally resolved; (c) helicity can be sustained across closed flux; and (d) IDCD current drive is parallel to the current which crosses the magnetic field to produce the current driving force. In addition to agreeing with spheromak data, IDCD agrees with selected tokamak data.

  11. Breakpoint Features of Genomic Rearrangements in Neuroblastoma with Unbalanced Translocations and Chromothripsis

    PubMed Central

    Daveau, Romain; Combaret, Valérie; Pierre-Eugène, Cécile; Cazes, Alex; Louis-Brennetot, Caroline; Schleiermacher, Gudrun; Ferrand, Sandrine; Pierron, Gaëlle; Lermine, Alban; Frio, Thomas Rio; Raynal, Virginie; Vassal, Gilles; Barillot, Emmanuel; Delattre, Olivier; Janoueix-Lerosey, Isabelle

    2013-01-01

    Neuroblastoma is a pediatric cancer of the peripheral nervous system in which structural chromosome aberrations are emblematic of aggressive tumors. In this study, we performed an in-depth analysis of somatic rearrangements in two neuroblastoma cell lines and two primary tumors using paired-end sequencing of mate-pair libraries and RNA-seq. The cell lines presented with typical genetic alterations of neuroblastoma and the two tumors belong to the group of neuroblastoma exhibiting a profile of chromothripsis. Inter and intra-chromosomal rearrangements were identified in the four samples, allowing in particular characterization of unbalanced translocations at high resolution. Using complementary experiments, we further characterized 51 rearrangements at the base pair resolution that revealed 59 DNA junctions. In a subset of cases, complex rearrangements were observed with templated insertion of fragments of nearby sequences. Although we did not identify known particular motifs in the local environment of the breakpoints, we documented frequent microhomologies at the junctions in both chromothripsis and non-chromothripsis associated breakpoints. RNA-seq experiments confirmed expression of several predicted chimeric genes and genes with disrupted exon structure including ALK, NBAS, FHIT, PTPRD and ODZ4. Our study therefore indicates that both non-homologous end joining-mediated repair and replicative processes may account for genomic rearrangements in neuroblastoma. RNA-seq analysis allows the identification of the subset of abnormal transcripts expressed from genomic rearrangements that may be involved in neuroblastoma oncogenesis. PMID:23991058

  12. Ion mass spectrometry investigations of the discharge during reactive high power pulsed and direct current magnetron sputtering of carbon in Ar and Ar/N{sub 2}

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Schmidt, S.; Greczynski, G.; Jensen, J.

    2012-07-01

    Ion mass spectrometry was used to investigate discharges formed during high power impulse magnetron sputtering (HiPIMS) and direct current magnetron sputtering (DCMS) of a graphite target in Ar and Ar/N{sub 2} ambient. Ion energy distribution functions (IEDFs) were recorded in time-averaged and time-resolved mode for Ar{sup +}, C{sup +}, N{sub 2}{sup +}, N{sup +}, and C{sub x}N{sub y}{sup +} ions. An increase of N{sub 2} in the sputter gas (keeping the deposition pressure, pulse width, pulse frequency, and pulse energy constant) results for the HiPIMS discharge in a significant increase in C{sup +}, N{sup +}, and CN{sup +} ion energies.more » Ar{sup +}, N{sub 2}{sup +}, and C{sub 2}N{sup +} ion energies, in turn, did not considerably vary with the changes in working gas composition. The HiPIMS process showed higher ion energies and fluxes, particularly for C{sup +} ions, compared to DCMS. The time evolution of the plasma species was analyzed for HiPIMS and revealed the sequential arrival of working gas ions, ions ejected from the target, and later during the pulse-on time molecular ions, in particular CN{sup +} and C{sub 2}N{sup +}. The formation of fullerene-like structured CN{sub x} thin films for both modes of magnetron sputtering is explained by ion mass-spectrometry results and demonstrated by transmission electron microscopy as well as diffraction.« less

  13. Coronal Jets in Closed Magnetic Regions on the Sun

    NASA Astrophysics Data System (ADS)

    Wyper, Peter Fraser; DeVore, C. R.

    2015-04-01

    Coronal jets are dynamic, collimated structures observed in solar EUV and X-ray emission. They appear predominantly in the open field of coronal holes, but are also observed in areas of closed field, especially active regions. A common feature of coronal jets is that they originate from the field above a parasitic polarity of opposite sign to the surrounding field. Some process - such as instability onset or flux emergence - induces explosive reconnection between the closed “anemone” field and the surrounding open field that generates the jet. The lesser number of coronal jets in closed-field regions suggests a possible stabilizing effect of the closed configuration with respect to coronal jet formation. If the scale of the jet region is small compared with the background loop length, as in for example type II spicules, the nearby magnetic field may be treated as locally open. As such, one would expect that if a stabilizing effect exists it becomes most apparent as the scale of the anemone region approaches that of the background coronal loops.To investigate if coronal jets are indeed suppressed along shorter coronal loops, we performed a number of simulations of jets driven by a rotation of the parasitic polarity (as in the previous open-jet calculations by Pariat et. al 2009, 2010, 2015) embedded in a large-scale closed bipolar field. The simulations were performed with the state of the art Adaptively Refined Magnetohydrodynamics Solver. We will report here how the magnetic configuration above the anemone region determines the nature of the jet, when it is triggered, and how much of the stored magnetic energy is released. We show that regions in which the background field and the parasitic polarity region are of comparable scale naturally suppress explosive energy release. We will also show how in the post-jet relaxation phase a combination of confined MHD waves and weak current layers are generated by the jet along the background coronal loops, both of which

  14. Evidence for breathing modes in direct current, pulsed, and high power impulse magnetron sputtering plasmas

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Yang, Yuchen; Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720; Zhou, Xue

    2016-01-18

    We present evidence for breathing modes in magnetron sputtering plasmas: periodic axial variations of plasma parameters with characteristic frequencies between 10 and 100 kHz. A set of azimuthally distributed probes shows synchronous oscillations of the floating potential. They appear most clearly when considering the intermediate current regime in which the direction of azimuthal spoke motion changes. Breathing oscillations were found to be superimposed on azimuthal spoke motion. Depending on pressure and current, one can also find a regime of chaotic fluctuations and one of stable discharges, the latter at high current. A pressure-current phase diagram for the different situations is proposed.

  15. FAST TRACK COMMUNICATION: Deposition of amino-rich thin films by RF magnetron sputtering of nylon

    NASA Astrophysics Data System (ADS)

    Kylián, O.; Hanuš, J.; Choukourov, A.; Kousal, J.; Slavínská, D.; Biederman, H.

    2009-07-01

    RF magnetron sputtering of a nylon target in different gas mixtures was studied in order to evaluate the capability of this process to deposit amino-rich coatings needed in a wide range of biomedical applications. It has been demonstrated that both the deposition rate of the coatings and the surface density of primary amino groups are strongly linked with working gas mixture composition. From this point of view, a sufficiently high deposition rate as well as the highest amine efficiency reaching a NH2/C value of 18% was observed in the N2/H2 discharge, which leads to the surface exhibiting a high rate of protein adsorption.

  16. Take a Field Trip Close to Home.

    ERIC Educational Resources Information Center

    Wood, Jacalyn K.

    1986-01-01

    Describes a simple field trip taken by fourth-grade students to a local park. Aided by volunteers, students go through four learning stations dealing with rock studies, tree identification, following directions (mapping), and observation skills. Presite and postsite activities are discussed. (TW)

  17. Propagation direction reversal of ionization zones in the transition between high and low current magnetron sputtering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    School of Materials Science and Engineering, State Key Lab for Materials Processing and Die & Mold Technology, Huazhong University of Science and Technology, Wuhan 430074, China; Department of Physics, University of California Berkeley, Berkeley, California 94720, USA; Lawrence Berkeley National Laboratory, 1 Cyclotron Road, Berkeley, California 94720, USA

    2014-12-11

    Past research has revealed the propagation of dense, asymmetric ionization zones in both high and low current magnetron discharges. Here we report about the direction reversal of ionization zone propagation as observed with fast cameras. At high currents, zones move in the E B direction with velocities of 103 to 104 m/s. However at lower currents, ionization zones are observed to move in the opposite, the -E B direction, with velocities ~;; 103 m/s. It is proposed that the direction reversal is associated with the local balance of ionization and supply of neutrals in the ionization zone.

  18. Probing domain switching dynamics in ferroelectric thick films by small field e31,f piezoelectric measurement

    NASA Astrophysics Data System (ADS)

    Cheng, Hongbo; Ouyang, Jun; Kanno, Isaku

    2017-07-01

    Epitaxial Pb(Zr0.53Ti0.47)O3 films were grown on (001) Pt/(001) MgO via rf-magnetron sputtering. Switching dynamics of 90° and 180° domains under bi-polar electric fields were probed by using small-field e31 ,f measurements in which the evolution of the transverse piezoelectric response with the bias voltage represents a set of fingerprints of the evolving domain structure. Furthermore, the asymmetric e31 ,f-V curves revealed a strong built-in electric field, which was verified by the standard polarization-electric field hysteresis measurement. Finally, X-ray 2θ-scan patterns under DC bias voltages were collected for the piezoelectric specimen. The domain switching sequence indicated by the XRD results is consistent with that revealed by the e31 ,f measurement.

  19. Design of a double-anode magnetron-injection gun for the W-band gyrotron

    NASA Astrophysics Data System (ADS)

    Jang, Kwang Ho; Choi, Jin Joo; So, Joon Ho

    2015-07-01

    A double-anode magnetron-injection gun (MIG) was designed. The MIG is for a W-band 10-kW gyrotron. Analytic equations based on adiabatic theory and angular momentum conservation were used to examine the initial design parameters such as the cathode angle, and the radius of the beam emitting surface. The MIG's performances were predicted by using an electron trajectory code, the EGUN code. The beam spread of the axial velocity, Δvz/vz, obtained from the EGUN code was observed to be 1.34% at α = 1.3. The cathode edge emission and the thermal effect were modeled. The cathode edge emission was found to have a major effect on the velocity spread. The electron beam's quality was significantly improved by affixing non-emissive cylinders to the cathode.

  20. Arsenic doped p-type zinc oxide films grown by radio frequency magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Fan, J. C.; Zhu, C. Y.; Fung, S.; Zhong, Y. C.; Wong, K. S.; Xie, Z.; Brauer, G.; Anwand, W.; Skorupa, W.; To, C. K.; Yang, B.; Beling, C. D.; Ling, C. C.

    2009-10-01

    As-doped ZnO films were grown by the radio frequency magnetron sputtering method. As the substrate temperature during growth was raised above ˜400 °C, the films changed from n type to p type. Hole concentration and mobility of ˜6×1017 cm-3 and ˜6 cm2 V-1 s-1 were achieved. The ZnO films were studied by secondary ion mass spectroscopy, x-ray photoelectron spectroscopy (XPS), low temperature photoluminescence (PL), and positron annihilation spectroscopy (PAS). The results were consistent with the AsZn-2VZn shallow acceptor model proposed by Limpijumnong et al. [Phys. Rev. Lett. 92, 155504 (2004)]. The results of the XPS, PL, PAS, and thermal studies lead us to suggest a comprehensive picture of the As-related shallow acceptor formation.

  1. Multilayered Al/CuO thermite formation by reactive magnetron sputtering: Nano versus micro

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Petrantoni, M.; Rossi, C.; Salvagnac, L.

    2010-10-15

    Multilayered Al/CuO thermite was deposited by a dc reactive magnetron sputtering method. Pure Al and Cu targets were used in argon-oxygen gas mixture plasma and with an oxygen partial pressure of 0.13 Pa. The process was designed to produce low stress (<50 MPa) multilayered nanoenergetic material, each layer being in the range of tens nanometer to one micron. The reaction temperature and heat of reaction were measured using differential scanning calorimetry and thermal analysis to compare nanostructured layered materials to microstructured materials. For the nanostructured multilayers, all the energy is released before the Al melting point. In the case ofmore » the microstructured samples at least 2/3 of the energy is released at higher temperatures, between 1036 and 1356 K.« less

  2. Comparative measurements of plasma potential with ball-pen and Langmuir probe in low-temperature magnetized plasma

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Zanáška, M.; Kudrna, P.; Tichý, M.

    The ball-pen probe (BPP) is used for direct plasma potential measurements in magnetized plasma. The probe can adjust the ratio of the electron and ion saturation currents I{sub sat}{sup −}/I{sub sat}{sup +} to be close to one and therefore its I-V characteristic becomes nearly symmetric. If this is achieved, the floating potential of the BPP is close to the plasma potential. Because of its rather simple construction, it offers an attractive probe for measurements in magnetized plasma. Comparative measurements of plasma potential by BPPs of different dimensions as well as one Langmuir probe (LP) in an argon discharge plasma ofmore » a cylindrical magnetron were performed at various experimental conditions. An additional comparison by an emissive probe was also performed. All these types of probes provide similar values of plasma potential in a wide range of plasma parameters. Our results for three different BPP dimensions indicate that the BPP can be operated in a cylindrical magnetron DC argon discharge if the value of the ratio of the magnetic field and neutral gas pressure, B/p, is greater than approximately 10 mT/Pa.« less

  3. Magnetic field effect on spoke behaviour

    NASA Astrophysics Data System (ADS)

    Hnilica, Jaroslav; Slapanska, Marta; Klein, Peter; Vasina, Petr

    2016-09-01

    The investigations of the non-reactive high power impulse magnetron sputtering (HiPIMS) discharge using high-speed camera imaging, optical emission spectroscopy and electrical probes showed that plasma is not homogeneously distributed over the target surface, but it is concentrated in regions of higher local plasma density called spokes rotating above the erosion racetrack. Magnetic field effect on spoke behaviour was studied by high-speed camera imaging in HiPIMS discharge using 3 inch titanium target. An employed camera enabled us to record two successive images in the same pulse with time delay of 3 μs between them, which allowed us to determine the number of spokes, spoke rotation velocity and spoke rotation frequency. The experimental conditions covered pressure range from 0.15 to 5 Pa, discharge current up to 350 A and magnetic fields of 37, 72 and 91 mT. Increase of the magnetic field influenced the number of spokes observed at the same pressure and at the same discharge current. Moreover, the investigation revealed different characteristic spoke shapes depending on the magnetic field strength - both diffusive and triangular shapes were observed for the same target material. The spoke rotation velocity was independent on the magnetic field strength. This research has been financially supported by the Czech Science Foundation in frame of the project 15-00863S.

  4. Implementation and initial test result of a prototype solid state modulator for pulsed magnetron

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Dake, Vishal; Mangalvedekar, H.A., E-mail: vishaldake90@gmail.com; Tillu, Abhijit

    2014-07-01

    A solid-state modulator rated for 50 kV, 120A, 4μs and 250 Hz has been designed. The discharging circuit of the modulator is being tested at ∼ 33 kV, 40-80A, at a maximum pulse repetition rate of 30 pps. The paper discusses development and testing of prototype discharging circuit on resistive load and magnetron. The technique used for measurement of pulse transformer leakage inductance, distributed capacitance and stray primary circuit series inductance will also be discussed in detail. It is necessary to have Energy Storage Capacitors with low ESL for these applications (ESL < 40 nH). The method used for evaluatingmore » the ESL of locally available metalized polypropylene capacitors will also be presented. (author)« less

  5. Catalytic activity and stability of nanometic Rh overlayers prepared by pulsed arc-plasma deposition and r.f. magnetron-sputtering

    NASA Astrophysics Data System (ADS)

    Misumi, Satoshi; Matsumoto, Akinori; Yoshida, Hiroshi; Sato, Tetsuya; Machida, Masato

    2018-01-01

    50 μm-thick Fe-Cr-Al metal foils covered by 7 nm-thick Rh overlayers were prepared by pulsed arc-plasma (AP) and r.f. magnetron sputtering technique to compare their catalytic activities. As-prepared metal foil catalysts were wrapped into a honeycomb structure with a density of 900 cells per square inches and the stoichiometric NO-CO-C3H6-O2 reaction was performed at space velocity of 1.2 × 105 h-1. During temperature ramp at 10 °C min-1, honeycomb catalysts showed steep light-off of NO, CO, and C3H6 at above 200 °C and their conversions soon reached to almost 100%. Both catalysts exhibited high turnover frequencies close to or more than 50-fold greater compared with those for a reference Rh/ZrO2 powder-coated cordierite honeycomb prepared using a conventional slurry coating. When the temperature ramping was repeated, however, the catalytic activity was decreased to the different extent depending on the preparation procedure. Significant deactivation occurred only when prepared by sputtering, whereas the sample prepared by AP showed no signs of deactivation. The deactivation is associated with the formation of passivation layers consisting of Fe, Cr, and Al oxides, which covered the surface and decreased the surface concentration of Rh. The Rh overlayer formed by AP was found to be thermally stable because of the strong adhesion to the metal foil surface, compared to the sample prepared by sputtering.

  6. Fabrication of oriented hydroxyapatite film by RF magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Hirata, Keishiro; Kubota, Takafumi; Koyama, Daisuke; Takayanagi, Shinji; Matsukawa, Mami

    2017-08-01

    Hydroxyapatite (HAp) is compatible with bone tissue and is used mainly as a bone prosthetic material, especially as the coating of implants. Oriented HAp film is expected to be a high-quality epitaxial scaffold of the neonatal bone. To fabricate highly oriented HAp thin films via the conventional plasma process, we deposited the HAp film on a Ti coated silica glass substrate using RF magnetron sputtering in low substrate temperature conditions. The X-ray diffraction pattern of the film sample consisted of an intense (002) peak, corresponding to the highly oriented HAp. The (002) peak in XRD diagrams can be attributed either to the monoclinic phase or the hexagonal phase. Pole figure analysis showed that the (002) plane grew parallel to the surface of the substrate, without inclination. Transmission Electron Microscope analysis also showed the fabrication of aligned HAp crystallites. The selected area diffraction patterns indicated the existence of monoclinic phase. The existence of hexagonal phase could not be judged. These results indicate the uniaxial films fabricated by this technique enable to be the epitaxial scaffold of the neonatal bone. This scaffold can be expected to promote connection with the surrounding bone tissue and recovery of the dynamic characteristics of the bone.

  7. Decorative black TiCxOy film fabricated by DC magnetron sputtering without importing oxygen reactive gas

    NASA Astrophysics Data System (ADS)

    Ono, Katsushi; Wakabayashi, Masao; Tsukakoshi, Yukio; Abe, Yoshiyuki

    2016-02-01

    Decorative black TiCxOy films were fabricated by dc (direct current) magnetron sputtering without importing the oxygen reactive gas into the sputtering chamber. Using a ceramic target of titanium oxycarbide (TiC1.59O0.31), the oxygen content in the films could be easily controlled by adjustment of total sputtering gas pressure without remarkable change of the carbon content. The films deposited at 2.0 and 4.0 Pa, those are higher pressure when compared with that in conventional magnetron sputtering, showed an attractive black color. In particular, the film at 4.0 Pa had the composition of TiC1.03O1.10, exhibited the L* of 41.5, a* of 0.2 and b* of 0.6 in CIELAB color space. These values were smaller than those in the TiC0.29O1.38 films (L* of 45.8, a* of 1.2 and b* of 1.2) fabricated by conventional reactive sputtering method from the same target under the conditions of gas pressure of 0.3 Pa and optimized oxygen reactive gas concentration of 2.5 vol.% in sputtering gas. Analysis of XRD and XPS revealed that the black film deposited at 4.0 Pa was the amorphous film composed of TiC, TiO and C. The adhesion property and the heat resisting property were enough for decorative uses. This sputtering process has an industrial advantage that the decorative black coating with color uniformity in large area can be easily obtained by plain operation because of unnecessary of the oxygen reactive gas importing which is difficult to be controlled uniformly in the sputtering chamber.

  8. Optical characterization of Mg-doped ZnO thin films deposited by RF magnetron sputtering technique

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Singh, Satyendra Kumar; Tripathi, Shweta; Hazra, Purnima

    2016-05-06

    This paper reports the in-depth analysis on optical characteristics of magnesium (Mg) doped zinc oxide (ZnO) thin films grown on p-silicon (Si) substrates by RF magnetron sputtering technique. The variable angle ellipsometer is used for the optical characterization of as-deposited thin films. The optical reflectance, transmission spectra and thickness of as-deposited thin films are measured in the spectral range of 300-800 nm with the help of the spectroscopic ellipsometer. The effect of Mg-doping on optical parameters such as optical bandgap, absorption coefficient, absorbance, extinction coefficient, refractive Index and dielectric constant for as-deposited thin films are extracted to show its application inmore » optoelectronic and photonic devices.« less

  9. Solid oxide fuel cells with apatite-type lanthanum silicate-based electrolyte films deposited by radio frequency magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Liu, Yi-Xin; Wang, Sea-Fue; Hsu, Yung-Fu; Wang, Chi-Hua

    2018-03-01

    In this study, solid oxide fuel cells (SOFCs) containing high-quality apatite-type magnesium doped lanthanum silicate-based electrolyte films (LSMO) deposited by RF magnetron sputtering are successfully fabricated. The LSMO film deposited at an Ar:O2 ratio of 6:4 on an anode supported NiO/Sm0.2Ce0·8O2-δ (SDC) substrate followed by post-annealing at 1000 °C reveals a uniform and dense c-axis oriented polycrystalline structure, which is well adhered to the anode substrate. A composite SDC/La0·6Sr0·4Co0·2Fe0·8O3-δ cathode layer is subsequently screen-printed on the LSMO deposited anode substrate and fired. The SOFC fabricated with the LSMO film exhibits good mechanical integrity. The single cell with the LSMO layer of ≈2.8 μm thickness reports a total cell resistance of 1.156 and 0.163 Ωcm2, open circuit voltage of 1.051 and 0.982 V, and maximum power densities of 0.212 and 1.490 Wcm-2 at measurement temperatures of 700 and 850 °C, respectively, which are comparable or superior to those of previously reported SOFCs with yttria stabilized zirconia electrolyte films. The results of the present study demonstrate the feasibility of deposition of high-quality LSMO films by RF magnetron sputtering on NiO-SDC anode substrates for the fabrication of SOFCs with good cell performance.

  10. High-Altitude Closed Magnetic Loops at Mars Observed by MAVEN

    NASA Astrophysics Data System (ADS)

    Xu, Shaosui; Mitchell, David; Luhmann, Janet; Ma, Yingjuan; Fang, Xiaohua; Harada, Yuki; Hara, Takuya; Brain, David; Weber, Tristan; Mazelle, Christian; DiBraccio, Gina A.

    2017-11-01

    With electron and magnetic field data obtained by the Mars Atmosphere and Volatile EvolutioN (MAVEN) spacecraft, we have identified closed magnetic field lines, with both foot points embedded in the dayside ionosphere, extending up to 6,200 km altitude into the Martian tail. This topology is deduced from photoelectrons produced in the dayside ionosphere being observed traveling both parallel and antiparallel to the magnetic field. At trapped-zone pitch angles (within a range centered on 90° where electrons magnetically reflect before interacting with the atmosphere), cases with either solar wind electrons or photoelectrons have been found, indicating different formation mechanisms for these closed loops. These large closed loops are present in MHD simulations. The case with field-aligned photoelectrons mixed with solar wind electrons having trapped-zone pitch angles is likely to be associated with reconnection, while the case with photoelectrons at all pitch angles is probably due to closed field lines being pulled tailward by the surrounding plasma flow. By utilizing an algorithm for distinguishing photoelectrons from solar wind electrons in pitch angle-resolved energy spectra, we systematically map the spatial distribution and occurrence rate of these closed magnetic loops over the region sampled by the MAVEN orbit. We find that the occurrence rate ranges from a few percent to a few tens of percent outside of the optical shadow and less than one percent within the shadow. These observations can be used to investigate the general magnetic topology in the tail, which is relevant to cold ion escape, reconnection, and flux ropes.

  11. Characterization and device applications of ZnO films deposited by high power impulse magnetron sputtering (HiPIMS)

    NASA Astrophysics Data System (ADS)

    Partridge, J. G.; Mayes, E. L. H.; McDougall, N. L.; Bilek, M. M. M.; McCulloch, D. G.

    2013-04-01

    ZnO films have been reactively deposited on sapphire substrates at 300 °C using a high impulse power magnetron sputtering deposition system and characterized structurally, optically and electronically. The unintentionally doped n-type ZnO films exhibit high transparency, moderate carrier concentration (˜5 × 1018 cm-3) and a Hall mobility of 8.0 cm2 V-1 s-1, making them suitable for electronic device applications. Pt/ZnO Schottky diodes formed on the HiPIMS deposited ZnO exhibited rectification ratios up to 104 at ±2 V and sensitivity to UV light.

  12. Rietveld-refinement and optical study of the Fe doped ZnO thin film by RF magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Kumar, Arun; Dhiman, Pooja; Singh, M.

    2017-05-01

    Fe Doped ZnO Dilute Magnetic Semiconductor thin film prepared by RF magnetron sputtering on glass substrate and Influence of 3% Fe-doping on structural and Optical properties has been studied. The Rietveld-refinement analysis shows that Fe doping has a significant effect on crystalline structure, grain size and strain in the thin film. Two dimensional and three-dimensional atom probe tomography of the thin film shows that Fe ions are randomly distributed which is supported by Xray Diffraction (XRD). Fe-doping is found to effectively modify the band gap energy up to 3.5 eV.

  13. Chemically induced porosity on BiVO4 films produced by double magnetron sputtering to enhance the photo-electrochemical response.

    PubMed

    Thalluri, Sitaramanjaneya Mouli; Rojas, Roberto Mirabal; Rivera, Osmary Depablos; Hernández, Simelys; Russo, Nunzio; Rodil, Sandra Elizabeth

    2015-07-21

    Double magnetron sputtering (DMS) is an efficient system that is well known because of its precise control of the thin film synthesizing process over any kind of substrate. Here, DMS has been adopted to synthesize BiVO4 films over a conducting substrate (FTO), using metallic vanadium and ceramic Bi2O3 targets simultaneously. The films were characterized using different techniques, such as X-ray diffraction (XRD), UV-Vis spectroscopy, Raman spectroscopy, X-ray photoelectron spectroscopy (XPS), field emission scanning electron microscopy (FESEM) and profilometry. The photo-electrochemical analysis was performed using linear scan voltammetry, chronoamperometry and electrochemical impedance spectroscopy (EIS) under the illumination of simulated solar light at 1 Sun. The photocurrent density of the sputtered BiVO4 thin films could be improved from 0.01 mA cm(-2) to 1.19 mA cm(-2) at 1.23 V vs. RHE by chemical treatment using potassium hydroxide (KOH). The effect of KOH was the removal of impurities from the grain boundaries, leading to a more porous structure and more pure crystalline monoclinic BiVO4 particles. Such variations in the microstructure as well as the improvement of the charge transfer properties of the BiVO4 film after the KOH treatment were confirmed and studied in depth by EIS analysis.

  14. Effect of negative bias on the composition and structure of the tungsten oxide thin films deposited by magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Wang, Meihan; Lei, Hao; Wen, Jiaxing; Long, Haibo; Sawada, Yutaka; Hoshi, Yoichi; Uchida, Takayuki; Hou, Zhaoxia

    2015-12-01

    Tungsten oxide thin films were deposited at room temperature under different negative bias voltages (Vb, 0 to -500 V) by DC reactive magnetron sputtering, and then the as-deposited films were annealed at 500 °C in air atmosphere. The crystal structure, surface morphology, chemical composition and transmittance of the tungsten oxide thin films were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), X-ray photoelectron spectroscopy (XPS) and UV-vis spectrophotometer. The XRD analysis reveals that the tungsten oxide films deposited at different negative bias voltages present a partly crystallized amorphous structure. All the films transfer from amorphous to crystalline (monoclinic + hexagonal) after annealing 3 h at 500 °C. Furthermore, the crystallized tungsten oxide films show different preferred orientation. The morphology of the tungsten oxide films deposited at different negative bias voltages is consisted of fine nanoscale grains. The grains grow up and conjunct with each other after annealing. The tungsten oxide films deposited at higher negative bias voltages after annealing show non-uniform special morphology. Substoichiometric tungsten oxide films were formed as evidenced by XPS spectra of W4f and O1s. As a result, semi-transparent films were obtained in the visible range for all films deposited at different negative bias voltages.

  15. Ultrasensitive hydrogen sensor based on Pt-decorated WO₃ nanorods prepared by glancing-angle dc magnetron sputtering.

    PubMed

    Horprathum, M; Srichaiyaperk, T; Samransuksamer, B; Wisitsoraat, A; Eiamchai, P; Limwichean, S; Chananonnawathorn, C; Aiempanakit, K; Nuntawong, N; Patthanasettakul, V; Oros, C; Porntheeraphat, S; Songsiriritthigul, P; Nakajima, H; Tuantranont, A; Chindaudom, P

    2014-12-24

    In this work, we report an ultrasensitive hydrogen (H2) sensor based on tungsten trioxide (WO3) nanorods decorated with platinum (Pt) nanoparticles. WO3 nanorods were fabricated by dc magnetron sputtering with a glancing angle deposition (GLAD) technique, and decorations of Pt nanoparticles were performed by normal dc sputtering on WO3 nanorods with varying deposition time from 2.5 to 15 s. Crystal structures, morphologies, and chemical information on Pt-decorated WO3 nanorods were characterized by grazing-incident X-ray diffraction, field-emission scanning electron microscopy, energy-dispersive X-ray spectroscopy, and photoelectron spectroscopy, respectively. The effect of the Pt nanoparticles on the H2-sensing performance of WO3 nanorods was investigated over a low concentration range of 150-3000 ppm of H2 at 150-350 °C working temperatures. The results showed that the H2 response greatly increased with increasing Pt-deposition time up to 10 s but then substantially deteriorated as the deposition time increased further. The optimally decorated Pt-WO3 nanorod sensor exhibited an ultrahigh H2 response from 1530 and 214,000 to 150 and 3000 ppm of H2, respectively, at 200 °C. The outstanding gas-sensing properties may be attributed to the excellent dispersion of fine Pt nanoparticles on WO3 nanorods having a very large effective surface area, leading to highly effective spillover of molecular hydrogen through Pt nanoparticles onto the WO3 nanorod surface.

  16. Low-loss interference filter arrays made by plasma-assisted reactive magnetron sputtering (PARMS) for high-performance multispectral imaging

    NASA Astrophysics Data System (ADS)

    Broßmann, Jan; Best, Thorsten; Bauer, Thomas; Jakobs, Stefan; Eisenhammer, Thomas

    2016-10-01

    Optical remote sensing of the earth from air and space typically utilizes several channels in the visible and near infrared spectrum. Thin-film optical interference filters, mostly of narrow bandpass type, are applied to select these channels. The filters are arranged in filter wheels, arrays of discrete stripe filters mounted in frames, or patterned arrays on a monolithic substrate. Such multi-channel filter assemblies can be mounted close to the detector, which allows a compact and lightweight camera design. Recent progress in image resolution and sensor sensitivity requires improvements of the optical filter performance. Higher demands placed on blocking in the UV and NIR and in between the spectral channels, in-band transmission and filter edge steepness as well as scattering lead to more complex filter coatings with thicknesses in the range of 10 - 25μm. Technological limits of the conventionally used ion-assisted evaporation process (IAD) can be overcome only by more precise and higher-energetic coating technologies like plasma-assisted reactive magnetron sputtering (PARMS) in combination with optical broadband monitoring. Optics Balzers has developed a photolithographic patterning process for coating thicknesses up to 15μm that is fully compatible with the advanced PARMS coating technology. This provides the possibility of depositing multiple complex high-performance filters on a monolithic substrate. We present an overview of the performance of recently developed filters with improved spectral performance designed for both monolithic filter-arrays and stripe filters mounted in frames. The pros and cons as well as the resulting limits of the filter designs for both configurations are discussed.

  17. Evaluation of the electrical conductivity and corrosion resistance for layers deposited via sputtering on stainless steel

    NASA Astrophysics Data System (ADS)

    Blanco, J.; Salas, Y.; Jiménez, C.; Pineda, Y.; Bustamante, A.

    2017-12-01

    In some Engineering fields, we need that conductive materials have a mechanic performance and specific electrical for that they maintain conditions or corrosive attack if they are in the environment or if they are closed structure. The stainless steels have an inert film on their surface and it has the function to act in contrast to external agents who generates the corrosion, especially for stings, spoiling the film until to fail. We found a solution taking into account the electrical performance and the anticorrosive; into the process we put recovering of specific oxides on, stainless steel using the method of sputtering with Unbalanced Magnetron, (UBM) varying the oxygen in the reactive environment. The coating obtained had a thickness one micron approximately and we saw on serious structural uniformity [1]. The corrosion resistance was evaluated through the potentiodynamics polarization and electrochemical spectroscopy impedance in NACL according to the standard. The cathode protection is the most important method employed for the corrosion prevention of metallic structures in the soil or immersed on the water. The electrical resistivity was evaluated with the four points methods and it showed a behaviour of diode type in some substrates with a threshold potential in several volts. We noticed a simple resistance solution when it was analysed in the Nyquist graphics whit the Electrochemical Impedance Spectroscopy technique. With on equivalent circuit, for this reason we determinate a variation in the corrosion speed in almost two orders of magnitude when we analysed the potentiodynamics curve by Tafel approximation. The data obtained and analysed show that this type of surface modification maintains the conductivity condition at the interface, improving the resistance in relation whit the corrosion of these elements where the recovering allowed the ionic flow wished for overcoming threshold voltage, acting as an insulator in different cases.

  18. Hopping conduction in zirconium oxynitrides thin film deposited by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Guo, Jie; Zhan, Guanghui; Liu, Jingquan; Yang, Bin; Xu, Bin; Feng, Jie; Chen, Xiang; Yang, Chunsheng

    2015-10-01

    Zirconium oxynitrides thin film thermometers were demonstrated to be useful temperature sensors. However, the basic conduction mechanism of zirconium oxynitrides films has been a long-standing issue, which hinders the prediction and optimization of their ultimate performance. In this letter, zirconium oxynitrides films were grown on sapphire substrates by magnetron sputtering and their electric transport mechanism has been systemically investigated. It was found that in high temperatures region (>150 K) the electrical conductivity was dominated by thermal activation for all samples. In the low temperatures range, while Mott variable hopping conduction (VRH) was dominated the transport for films with relatively low resistance, a crossover from Mott VRH conduction to Efros-Shklovskii (ES) VRH was observed for films with relatively high resistance. This low temperature crossover from Mott to ES VRH indicates the presence of a Coulomb gap (~7 meV). These results demonstrate the competing and tunable conduction mechanism in zirconium oxynitrides thin films, which would be helpful for optimizing the performance of zirconium oxynitrides thermometer.

  19. Zinc Oxide-Based Schottky Diode Prepared Using Radio-Frequency Magnetron Cosputtering System

    NASA Astrophysics Data System (ADS)

    Lai, Bo-Ting; Lee, Ching-Ting; Hong, Jhen-Dong; Yao, Shiau-Lu; Liu, Day-Shan

    2010-08-01

    The rectifying property of a zinc oxide (ZnO)-based Schottky diode prepared using a radio-frequency (rf) magnetron cosputtering system was improved by enhancing the cosputtered ZnO crystal quality, thereby optimizing the ohmic contact resistance and compensating the Schottky contact surface states. An undoped ZnO layer with a high c-axis orientation and a low internal residual stress was achieved using a postannealing treatment. A homogeneous n-type ZnO-indium tin oxide (ITO) cosputtered film was deposited onto the undoped ZnO layer to optimize the ohmic contact behavior to the Al electrode. The Schottky contact surface of the undoped ZnO layer to the Ni/Au electrode was passivated using an oxygen plasma treatment. Owing to the compensation of the native oxygen vacancies (VO) on the undoped ZnO surface, the leakage current markedly decreased and subsequently led to a quality Schottky diode performance with an ideality factor of 1.23 and a Schottky barrier height of 0.82 eV.

  20. Boron-rich plasma by high power impulse magnetron sputtering of lanthanum hexaboride

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Oks, Efim M.; Anders, Andre

    2012-10-15

    Boron-rich plasmas have been obtained using a LaB{sub 6} target in a high power impulse sputtering (HiPIMS) system. The presence of {sup 10}B{sup +}, {sup 11}B{sup +}, Ar{sup 2+}, Ar{sup +}, La{sup 2+}, and La{sup +} and traces of La{sup 3+}, {sup 12}C{sup +}, {sup 14}N{sup +}, and {sup 16}O{sup +} have been detected using an integrated mass and energy spectrometer. Peak currents as low as 20 A were sufficient to obtain plasma dominated by {sup 11}B{sup +} from a 5 cm planar magnetron. The ion energy distribution function for boron exhibits an energetic tail extending over several 10 eV,more » while argon shows a pronounced peak at low energy (some eV). This is in agreement with models that consider sputtering (B, La) and gas supply (from background and 'recycling'). Strong voltage oscillations develop at high current, greatly affecting power dissipation and plasma properties.« less

  1. Characteristics of a-IGZO/ITO hybrid layer deposited by magnetron sputtering.

    PubMed

    Bang, Joon-Ho; Park, Hee-Woo; Cho, Sang-Hyun; Song, Pung-Keun

    2012-04-01

    Transparent a-IGZO (In-Ga-Zn-O) films have been actively studied for use in the fabrication of high-quality TFTs. In this study, a-IGZO films and a-IGZO/ITO double layers were deposited by DC magnetron sputtering under various oxygen flow rates. The a-IGZO films showed an amorphous structure up to 500 degrees C. The deposition rate of these films decreased with an increase in the amount of oxygen gas. The amount of indium atoms in the film was confirmed to be 11.4% higher than the target. The resistivity of double layer follows the rules for parallel DC circuits The maximum Hall mobility of the a-IGZO/ITO double layers was found to be 37.42 cm2/V x N s. The electrical properties of the double layers were strongly dependent on their thickness ratio. The IGZO/ITO double layer was subjected to compressive stress, while the ITO/IGZO double layer was subjected to tensile stress. The bending tolerance was found to depend on the a-IGZO thickness.

  2. Amorphous indium-tin-zinc oxide films deposited by magnetron sputtering with various reactive gases: Spatial distribution of thin film transistor performance

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jia, Junjun; Torigoshi, Yoshifumi; Shigesato, Yuzo, E-mail: yuzo@chem.aoyama.ac.jp

    This work presents the spatial distribution of electrical characteristics of amorphous indium-tin-zinc oxide film (a-ITZO), and how they depend on the magnetron sputtering conditions using O{sub 2}, H{sub 2}O, and N{sub 2}O as the reactive gases. Experimental results show that the electrical properties of the N{sub 2}O incorporated a-ITZO film has a weak dependence on the deposition location, which cannot be explained by the bombardment effect of high energy particles, and may be attributed to the difference in the spatial distribution of both the amount and the activity of the reactive gas reaching the substrate surface. The measurement for themore » performance of a-ITZO thin film transistor (TFT) also suggests that the electrical performance and device uniformity of a-ITZO TFTs can be improved significantly by the N{sub 2}O introduction into the deposition process, where the field mobility reach to 30.8 cm{sup 2} V{sup –1} s{sup –1}, which is approximately two times higher than that of the amorphous indium-gallium-zinc oxide TFT.« less

  3. Developing Multilayer Thin Film Strain Sensors With High Thermal Stability

    NASA Technical Reports Server (NTRS)

    Wrbanek, John D.; Fralick, Gustave C.; Gonzalez, Jose M., III

    2006-01-01

    A multilayer thin film strain sensor for large temperature range use is under development using a reactively-sputtered process. The sensor is capable of being fabricated in fine line widths utilizing the sacrificial-layer lift-off process that is used for micro-fabricated noble-metal sensors. Tantalum nitride films were optimized using reactive sputtering with an unbalanced magnetron source. A first approximation model of multilayer resistance and temperature coefficient of resistance was used to set the film thicknesses in the multilayer film sensor. Two multifunctional sensors were fabricated using multilayered films of tantalum nitride and palladium chromium, and tested for low temperature resistivity, TCR and strain response. The low temperature coefficient of resistance of the films will result in improved stability in thin film sensors for low to high temperature use.

  4. Crystalline TiO 2 grafted with poly(2-methacryloyloxyethyl phosphorylcholine) via surface-initiated atom-transfer radical polymerization

    NASA Astrophysics Data System (ADS)

    Zhao, Yuancong; Tu, Qiufen; Wang, Jin; Huang, Qiongjian; Huang, Nan

    2010-12-01

    Crystalline TiO 2 films were prepared by unbalanced magnetron sputtering and the structure was confirmed by XRD. An organic layer of 11-hydroxyundecylphosphonic acid (HUPA) was prepared on the TiO 2 films by self-assembling, and the HUPA on TiO 2 films was confirmed by FTIR analysis. Simultaneously, hydroxyl groups were introduced in the phosphonic acid molecules to provide a functionality for further chemical modification. 2-Methacryloyloxyethyl phosphorylcholine (MPC), a biomimetic monomer, was chemically grafted on the HUPA surfaces at room temperature by surface-initiated atom-transfer radical polymerization. The surface characters of TiO 2 films modified by poly-MPC were confirmed by FTIR, XPS and SEM analysis. Platelet adhesion experiment revealed that poly-MPC modified surface was effective to inhibit platelet adhesion in vitro.

  5. Hierarchical structure graphitic-like/MoS2 film as superlubricity material

    NASA Astrophysics Data System (ADS)

    Gong, Zhenbin; Jia, Xiaolong; Ma, Wei; Zhang, Bin; Zhang, Junyan

    2017-08-01

    Friction and wear result in a great amount of energy loss and the invalidation of mechanical parts, thus it is necessary to minimize friction in practical application. In this study, the graphitic-like/MoS2 films with hierarchical structure were synthesized by the combination of pulse current plasma chemical-vapor deposition and medium frequency unbalanced magnetron sputtering in preheated environment. This hierarchical structure composite with multilayer nano sheets endows the films excellent tribological performance, which easily achieves macro superlubricity (friction coefficient ∼0.004) under humid air. Furthermore, it is expected that hierarchical structure of graphitic-like/MoS2 films could match the requirements of large scale, high bear-capacity and wear-resistance of actual working conditions, which could be widely used in the industrial production as a promising superlubricity material.

  6. Cleaning of HT-7 Tokamak Exposed First Mirrors by Radio Frequency Magnetron Sputtering Plasma

    NASA Astrophysics Data System (ADS)

    Yan, Rong; Chen, Junling; Chen, Longwei; Ding, Rui; Zhu, Dahuan

    2014-12-01

    The stainless steel (SS) first mirror pre-exposed in the deposition-dominated environment of the HT-7 tokamak was cleaned in the newly built radio frequency (RF) magnetron sputtering plasma device. The deposition layer on the FM surface formed during the exposure was successfully removed by argon plasma with a RF power of about 80 W and a gas pressure of 0.087 Pa for 30 min. The total reflectivity of the mirrors was recovered up to 90% in the wavelength range of 300-800 nm, while the diffuse reflectivity showed a little increase, which was attributed to the increase of surface roughness in sputtering, and residual contaminants. The FMs made from single crystal materials could help to achieve a desired recovery of specular reflectivity in the future.

  7. Optimized dielectric properties of SrTiO3:Nb /SrTiO3 (001) films for high field effect charge densities

    NASA Astrophysics Data System (ADS)

    Cai, Xiuyu; Frisbie, C. Daniel; Leighton, C.

    2006-12-01

    The authors report the growth, structural and electrical characterizations of SrTiO3 films deposited on conductive SrTiO3:Nb (001) substrates by high pressure reactive rf magnetron sputtering. Optimized deposition parameters yield smooth epitaxial layers of high crystalline perfection with a room temperature dielectric constant ˜200 (for a thickness of 1150Å). The breakdown fields in SrTiO3:Nb /SrTiO3/Ag capacitors are consistent with induced charge densities >1×1014cm-2 for both holes and electrons, making these films ideal for high charge density field effect devices.

  8. Noncommutative-geometry model for closed bosonic strings

    NASA Technical Reports Server (NTRS)

    Sen, Siddhartha; Holman, R.

    1987-01-01

    It is shown how Witten's (1986) noncommutative geometry may be extended to describe the closed bosonic string. For closed strings, an explicit representation is provided of the integral operator needed to construct an action and of an associative product on string fields. The proper choice of the action of the integral operator and the associative product in order to give rise to a reasonable theory is explained, and the consequences of such a choice are discussed. It is shown that the ghost numbers of the operator and associative product can be chosen arbitrarily for both open and closed strings, and that this construct can be used as an action for interacting closed bosonic strings.

  9. Close Air Support in a Joint Environment: Disconnect Between the Services and How Can Close Air Support Be Improved

    DTIC Science & Technology

    2013-04-05

    military expecting technology to close the gap between the lack of CAS training and the expected pilot proficiency in multiple roles? To be an... Research Project. Carlisle Barracks: U.S. Army War College, 19 March 2004. McGrath, John. Fire for Effect: Field Artillery and Close Air Support in...including suggestions for reducing this burden to Department of Defense, Washington Headquarters Services, Directorate for Information Operations

  10. Practical quantum private query of blocks based on unbalanced-state Bennett-Brassard-1984 quantum-key-distribution protocol

    NASA Astrophysics Data System (ADS)

    Wei, Chun-Yan; Gao, Fei; Wen, Qiao-Yan; Wang, Tian-Yin

    2014-12-01

    Until now, the only kind of practical quantum private query (QPQ), quantum-key-distribution (QKD)-based QPQ, focuses on the retrieval of a single bit. In fact, meaningful message is generally composed of multiple adjacent bits (i.e., a multi-bit block). To obtain a message from database, the user Alice has to query l times to get each ai. In this condition, the server Bob could gain Alice's privacy once he obtains the address she queried in any of the l queries, since each ai contributes to the message Alice retrieves. Apparently, the longer the retrieved message is, the worse the user privacy becomes. To solve this problem, via an unbalanced-state technique and based on a variant of multi-level BB84 protocol, we present a protocol for QPQ of blocks, which allows the user to retrieve a multi-bit block from database in one query. Our protocol is somewhat like the high-dimension version of the first QKD-based QPQ protocol proposed by Jacobi et al., but some nontrivial modifications are necessary.

  11. Practical quantum private query of blocks based on unbalanced-state Bennett-Brassard-1984 quantum-key-distribution protocol

    PubMed Central

    Wei, Chun-Yan; Gao, Fei; Wen, Qiao-Yan; Wang, Tian-Yin

    2014-01-01

    Until now, the only kind of practical quantum private query (QPQ), quantum-key-distribution (QKD)-based QPQ, focuses on the retrieval of a single bit. In fact, meaningful message is generally composed of multiple adjacent bits (i.e., a multi-bit block). To obtain a message from database, the user Alice has to query l times to get each ai. In this condition, the server Bob could gain Alice's privacy once he obtains the address she queried in any of the l queries, since each ai contributes to the message Alice retrieves. Apparently, the longer the retrieved message is, the worse the user privacy becomes. To solve this problem, via an unbalanced-state technique and based on a variant of multi-level BB84 protocol, we present a protocol for QPQ of blocks, which allows the user to retrieve a multi-bit block from database in one query. Our protocol is somewhat like the high-dimension version of the first QKD-based QPQ protocol proposed by Jacobi et al., but some nontrivial modifications are necessary. PMID:25518810

  12. Electric-field-induced assembly and propulsion of chiral colloidal clusters.

    PubMed

    Ma, Fuduo; Wang, Sijia; Wu, David T; Wu, Ning

    2015-05-19

    Chiral molecules with opposite handedness exhibit distinct physical, chemical, or biological properties. They pose challenges as well as opportunities in understanding the phase behavior of soft matter, designing enantioselective catalysts, and manufacturing single-handed pharmaceuticals. Microscopic particles, arranged in a chiral configuration, could also exhibit unusual optical, electric, or magnetic responses. Here we report a simple method to assemble achiral building blocks, i.e., the asymmetric colloidal dimers, into a family of chiral clusters. Under alternating current electric fields, two to four lying dimers associate closely with a central standing dimer and form both right- and left-handed clusters on a conducting substrate. The cluster configuration is primarily determined by the induced dipolar interactions between constituent dimers. Our theoretical model reveals that in-plane dipolar repulsion between petals in the cluster favors the achiral configuration, whereas out-of-plane attraction between the central dimer and surrounding petals favors a chiral arrangement. It is the competition between these two interactions that dictates the final configuration. The theoretical chirality phase diagram is found to be in excellent agreement with experimental observations. We further demonstrate that the broken symmetry in chiral clusters induces an unbalanced electrohydrodynamic flow surrounding them. As a result, they rotate in opposite directions according to their handedness. Both the assembly and propulsion mechanisms revealed here can be potentially applied to other types of asymmetric particles. Such kinds of chiral colloids will be useful for fabricating metamaterials, making model systems for both chiral molecules and active matter, or building propellers for microscale transport.

  13. Substantial difference in target surface chemistry between reactive dc and high power impulse magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Greczynski, G.; Mráz, S.; Schneider, J. M.; Hultman, L.

    2018-02-01

    The nitride layer formed in the target race track during the deposition of stoichiometric TiN thin films is a factor 2.5 thicker for high power impulse magnetron sputtering (HIPIMS), compared to conventional dc processing (DCMS). The phenomenon is explained using x-ray photoelectron spectroscopy analysis of the as-operated Ti target surface chemistry supported by sputter depth profiles, dynamic Monte Carlo simulations employing the TRIDYN code, and plasma chemical investigations by ion mass spectrometry. The target chemistry and the thickness of the nitride layer are found to be determined by the implantation of nitrogen ions, predominantly N+ and N2+ for HIPIMS and DCMS, respectively. Knowledge of this method-inherent difference enables robust processing of high quality functional coatings.

  14. Effect of thickness on surface morphology, optical and humidity sensing properties of RF magnetron sputtered CCTO thin films

    NASA Astrophysics Data System (ADS)

    Ahmadipour, Mohsen; Ain, Mohd Fadzil; Ahmad, Zainal Arifin

    2016-11-01

    In this study, calcium copper titanate (CCTO) thin films were deposited on ITO substrates successfully by radio frequency (RF) magnetron sputtering method in argon atmosphere. The CCTO thin films present a polycrystalline, uniform and porous structure. The surface morphology, optical and humidity sensing properties of the synthesized CCTO thin films have been studied by X-ray diffraction (XRD), atomic force microscopy (AFM), field emission scanning electron microscopy (FESEM), energy-dispersive X-ray spectroscopy (EDX), UV-vis spectrophotometer and current-voltage (I-V) analysis. XRD and AFM confirmed that the intensity of peaks and pore size of CCTO thin films were enhanced by increasing the thin films. Tauc plot method was adopted to estimate the optical band gaps. The surface structure and energy band gaps of the deposited films were affected by film thickness. Energy band gap of the layers were 3.76 eV, 3.68 eV and 3.5 eV for 200 nm, 400 nm, and 600 nm CCTO thin films layer, respectively. The humidity sensing properties were measured by using direct current (DC) analysis method. The response times were 12 s, 22 s, and 35 s while the recovery times were 500 s, 600 s, and 650 s for 200 nm, 400 nm, and 600 nm CCTO thin films, respectively at humidity range of 30-90% relative humidity (RH).

  15. Tunable dielectric properties of Barium Magnesium Niobate (BMN) doped Barium Strontium Titanate (BST) thin films by magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Alema, Fikadu; Reinholz, Aaron; Pokhodnya, Konstantin

    2013-03-01

    We report on the tunable dielectric properties of Mg and Nb co-doped Ba0.45Sr0.55TiO3 (BST) thin film prepared by the magnetron sputtering using BST target (pure and doped with BaMg0.33Nb0.67O3 (BMN)) on Pt/TiO2/SiO2/Al2O3 4'' wafers at 700 °C under oxygen atmosphere. The electrical measurements are conducted on 2432 metal-ferroelectric-metal capacitors using Pt as the top and bottom electrode. The crystalline structure, microstructure, and surface morphology of the films are analyzed and correlated to the films dielectric properties. The BMN doped and undoped BST films have shown tunabilities of 48% and 52%; and leakage current densities of 2.2x10-6 A/cm2 and 3.7x10-5 A/cm2, respectively at 0.5 MV/cm bias field. The results indicate that the BMN doped film exhibits a lower leakage current with no significant decrease in tunability. Due to similar electronegativity and ionic radii, it was suggested that both Mg2+ (accepter-type) and Nb5+ (donor-type) dopants substitutTi4+ ion in BST. The improvement in the film dielectric losses and leakage current with insignificant loss of tunability is attributed to the adversary effects of Mg2+ and Nb5+ in BST.

  16. Deposition of the low resistive ITO-films by means of reactive magnetron sputtering of the In/Sn target on the cold substrate

    NASA Astrophysics Data System (ADS)

    Zhidik, Y. S.; Troyan, P. E.; Baturina, E. V.; Korzhenko, D. V.; Yurjev, Y. N.

    2016-06-01

    Detailed information on the deposition technology of the low-resistive ITO-films in oxygen-containing media by magnetron reactive sputtering from the In(90%)/Sn(10%) target on the cold substrate is given. Developed technology allows deposition ITO-films with sheet resistance 2-3 Ω/□, transparency higher than 90%. Developed technology is notable for high reproducibility of results and is compatible with production technology of semiconductor devices of optoelectronics.

  17. Reversible superhydrophilicity and hydrophobicity switching of V2O5 thin films deposited by magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Zhang, Chunzi; Peng, Zhiguang; Cui, Xiaoyu; Neil, Eric; Li, Yuanshi; Kasap, Safa; Yang, Qiaoqin

    2018-03-01

    V2O5 thin films are well-known "smart" materials due to their reversible wettability under UV irradiation and dark storage. Their surfaces are usually hydrophobic and turn into hydrophilic under UV irradiation. However, the V2O5 thin films deposited by magnetron sputtering in present work are superhydrophilic and turned into hydrophobic after days' of storage in air. This change can be recovered by heating. The effects of many factors including surface roughness, irradiation from visible light, UV, & X-ray, and storage in air & vacuum on the reversible switching of wettability were investigated. The results show that air absorption is the main factor causing the film surface change from superhydrophilicity to hydrophobicity.

  18. Magnetron sputtering based direct fabrication of three dimensional CdTe hierarchical nanotrees exhibiting stable superhydrophobic property

    NASA Astrophysics Data System (ADS)

    Luo, Bingwei; Deng, Yuan; Wang, Yao; Shi, Yongming; Cao, Lili; Zhu, Wei

    2013-09-01

    Three dimensional CdTe hierarchical nanotrees are initially prepared by a simple one-step magnetron sputtering method without any templates or additives. The CdTe hierarchical nanotrees are constructed by the spear-like vertical trunks and horizontal branches with the diameters of about 100 nm at bottom and became cuspidal on the top. The particular nanostructure imparts these materials superhydrophobic property, and this property can be preserved after placing in air for 90 days, and is stable even after the ultraviolet light and X-ray irradiation, respectively. This study provides a simple strategy to achieve superhydrophobic properties for CdTe materials at lower temperature, which opens a new potential for CdTe solar cell with self-cleaning property.

  19. High quality boron carbon nitride/ZnO-nanorods p-n heterojunctions based on magnetron sputtered boron carbon nitride films

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Qian, J. C.; Department of Engineering Physics, Polytechnique Montréal, Montreal, Quebec H3A 3A7; Jha, S. K., E-mail: skylec@gmail.com, E-mail: apwjzh@cityu.edu.hk

    2014-11-10

    Boron carbon nitride (BCN) films were synthesized on Si (100) and fused silica substrates by radio-frequency magnetron sputtering from a B{sub 4}C target in an Ar/N{sub 2} gas mixture. The BCN films were amorphous, and they exhibited an optical band gap of ∼1.0 eV and p-type conductivity. The BCN films were over-coated with ZnO nanorod arrays using hydrothermal synthesis to form BCN/ZnO-nanorods p-n heterojunctions, exhibiting a rectification ratio of 1500 at bias voltages of ±5 V.

  20. Effect of Silver Dopants on the ZnO Thin Films Prepared by a Radio Frequency Magnetron Co-Sputtering System

    PubMed Central

    Liu, Fang-Cheng; Li, Jyun-Yong; Chen, Tai-Hong; Chang, Chun-How; Lee, Ching-Ting; Hsiao, Wei-Hua; Liu, Day-Shan

    2017-01-01

    Ag-ZnO co-sputtered films at various atomic ratios of Ag (Ag/(Ag + Zn) at.%) were prepared by a radio frequency magnetron cosputtering system, using the co-sputtered targets of Ag and ZnO. The activation of the Ag acceptors (AgZn) and the formation of the Ag aggregations (Ag0) in the ZnO matrix were investigated from XRD, Raman scattering, and XPS measurements. The Ag-ZnO co-sputtered film behaving like a p-type conduction was achievable after annealing at 350 °C under air ambient for 1 h. PMID:28773159

  1. Effect of film thickness on structural and mechanical properties of AlCrN nanocompoite thin films deposited by reactive DC magnetron sputtering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Prakash, Ravi; Kaur, Davinder, E-mail: dkaurfph@iitr.ac.in

    2016-05-06

    In this study, the influence of film thickness on the structural, surface morphology and mechanical properties of Aluminum chromium nitride (AlCrN) thin films has been successfully investigated. The AlCrN thin films were deposited on silicon (100) substrate using dc magnetron reactive co-sputtering at substrate temperature 400° C. The structural, surface morphology and mechanical properties were studied using X-ray diffraction, field-emission scanning electron microscopy and nanoindentation techniques respectively. The thickness of these thin films was controlled by varying the deposition time therefore increase in deposition time led to increase in film thickness. X-ray diffraction pattern of AlCrN thin films with differentmore » deposition time shows the presence of (100) and (200) orientations. The crystallite size varies in the range from 12.5 nm to 36.3 nm with the film thickness due to surface energy minimization with the higher film thickness. The hardness pattern of these AlCrN thin films follows Hall-Petch relation. The highest hardness 23.08 Gpa and young modulus 215.31 Gpa were achieved at lowest grain size of 12.5 nm.« less

  2. Characterization of ZnO:SnO{sub 2} (50:50) thin film deposited by RF magnetron sputtering technique

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Cynthia, S. R.; Sanjeeviraja, C.; Ponmudi, S.

    2016-05-06

    Zinc oxide (ZnO) and tin oxide (SnO{sub 2}) thin films have attracted significant interest recently for use in optoelectronic application such as solar cells, flat panel displays, photonic devices, laser diodes and gas sensors because of their desirable electrical and optical properties and wide band gap. In the present study, thin films of ZnO:SnO{sub 2} (50:50) were deposited on pre-cleaned microscopic glass substrate by RF magnetron sputtering technique. The substrate temperature and RF power induced changes in structural, surface morphological, compositional and optical properties of the films have been studied.

  3. Numerical Simulation of Single-anode and Double-anode Magnetron Injection Guns for 127.5 GHz 1 MW Gyrotron

    NASA Astrophysics Data System (ADS)

    Singh, Udaybir; Kumar, Nitin; Kumar, Anil; Purohit, Laxmi Prasad; Sinha, Ashok Kumar

    2011-07-01

    This paper presents the design of two types of magnetron injection guns (MIG's) for 1 MW, 127.5 GHz gyrotron. TE24,8 mode has been chosen as the operating mode. In-house developed code MIGSYN has been used to estimate the initial gun parameters. The electron trajectory tracing program EGUN and in-house developed code MIGANS have been used to optimize the single-anode and the double-anode design for 80 kV, 40 A MIG. The parametric analysis of MIG has also been presented. The advantages and the disadvantages of each kind of configuration have been critically examined.

  4. Defect free C-axis oriented zinc oxide (ZnO) films grown at room temperature using RF magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Kunj, Saurabh; Sreenivas, K.

    2016-05-01

    Radio frequency Magnetron sputtering technique was employed to fabricate ZnO thin films on quartz substrate at room temperature. The effect of varying oxygen to argon (O2/Ar) gas ratio on the structural and photoluminescence properties of the film is analyzed.X-ray diffraction (XRD) spectra reveals the formation of hexagonal wurtzite structured ZnO thin films with preferred orientation along (002) plane. Photoluminescence (PL) characterization reveals the preparation of highly crystalline films exhibiting intense Ultraviolet (UV) emission with negligible amount of defects as indicated by the absence of Deep Level Emission (DLE) in the PL spectra.

  5. Defect free C-axis oriented zinc oxide (ZnO) films grown at room temperature using RF magnetron sputtering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Kunj, Saurabh, E-mail: saurabhkunj22@gmail.com; Sreenivas, K.

    2016-05-23

    Radio frequency Magnetron sputtering technique was employed to fabricate ZnO thin films on quartz substrate at room temperature. The effect of varying oxygen to argon (O{sub 2}/Ar) gas ratio on the structural and photoluminescence properties of the film is analyzed.X-ray diffraction (XRD) spectra reveals the formation of hexagonal wurtzite structured ZnO thin films with preferred orientation along (002) plane. Photoluminescence (PL) characterization reveals the preparation of highly crystalline films exhibiting intense Ultraviolet (UV) emission with negligible amount of defects as indicated by the absence of Deep Level Emission (DLE) in the PL spectra.

  6. Influence of argon pressure and current density on substrate temperature during magnetron sputtering of hot titanium target

    NASA Astrophysics Data System (ADS)

    Komlev, Anton A.; Minzhulina, Ekaterina A.; Smirnov, Vladislav V.; Shapovalov, Viktor I.

    2018-01-01

    The paper describes physical characteristics of the hot target sputtering process, which have not been known before. To switch a magnetron over to the hot target regime, a titanium disk of 1 mm thick with a 1-mm-gap was attached on a 4-mm-thick copper plate cooled by running water. A thermocouple sensor was used to investigate the thermal processes occurring in substrates. The study was performed at the discharge current density of 20-40 mA/cm2 and argon pressure of 3-7 mTorr. The accuracy of temperature measurement appeared to be within ± 5%, due the application of a chromel-copel thermocouple. The study reveals that under these conditions the heating curves have the inflection points positioned proportionally to the discharge current density and argon pressure on a time axis. The inflection point appears in the kinetic curves due to the finite value of the target heating time constant. The study shows that the substrate fixed temperature and substrate heating time constant depend on the argon pressure and relate to the current density by the polynomials of the first and second degrees, respectively. The influence of a target on the substrate heating kinetics is considered in an analytical description by the introduction of a multiplier in the form of an exponential function of time. The results of the research make a novel contribution to the field of the sputtering process.

  7. Diagnostics of RF magnetron sputtering plasma for synthesizing transparent conductive Indium-Zinc-Oxide film

    NASA Astrophysics Data System (ADS)

    Ohta, Takayuki; Inoue, Mari; Takota, Naoki; Ito, Masafumi; Higashijima, Yasuhiro; Kano, Hiroyuki; den, Shoji; Yamakawa, Koji; Hori, Masaru

    2009-10-01

    Transparent conductive Oxide film has been used as transparent conducting electrodes of optoelectronic devices such as flat panel display, solar cells, and so on. Indium-Zinc-Oxide (IZO) has been investigated as one of promising alternatives Indium Tin Oxide film, due to amorphous, no nodule and so on. In order to control a sputtering process with highly precise, RF magnetron sputtering plasma using IZO composite target was diagnosed by absorption and emission spectroscopy. We have developed a multi-micro hollow cathode lamp which can emit simultaneous multi-atomic lines for monitoring Zn and In densities simultaneously. Zn and In densities were measured to be 10^9 from 10^10 cm-3 at RF power from 40 to 100 W, pressure of 5Pa, and Ar flow rate of 300 sccm. The emission intensities of Zn, In, InO, and Ar were also observed.

  8. Effect of sputtering power on the growth of Ru films deposited by magnetron sputtering

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Jhanwar, Prachi, E-mail: prachijhanwar87@gmail.com; Department of Electronics, Banasthali University-304022, Rajasthan; Kumar, Arvind

    2016-04-13

    Ruthenium is deposited by DC magnetron sputtering at different powers and is characterized. The effect of sputtering power on the electrical and structural properties of the film is investigated experimentally. High resolution X-ray diffraction is used to characterize the microstructure of Ru films deposited on SiO{sub 2} surface. The peak (002) is more sharp and intense with full width at half maximum (FWHM) of 0.37° at 250W. The grain size increases with increase in sputtering power improving the crystallinity of the film. The film deposited at high sputtering power also showed lower resistivity (12.40 µΩ-cm) and higher mobility (4.82 cm{sup 2}/V.s) asmore » compared to the film deposited at low power. The surface morphology of the film is studied by atomic force microscopy (AFM).« less

  9. High-voltage, high-current, solid-state closing switch

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Focia, Ronald Jeffrey

    2017-08-22

    A high-voltage, high-current, solid-state closing switch uses a field-effect transistor (e.g., a MOSFET) to trigger a high-voltage stack of thyristors. The switch can have a high hold-off voltage, high current carrying capacity, and high time-rate-of-change of current, di/dt. The fast closing switch can be used in pulsed power applications.

  10. Closing the wildland fire heat budget - measurements in the field at intermediate and operational scales

    NASA Astrophysics Data System (ADS)

    Dickinson, M.; Kremens, R.; Bova, A. S.

    2012-12-01

    Closing the wildland fire heat budget involves characterizing the heat source and energy dissipation across the range of variability in fuels and fire behavior. Meeting this challenge will lay the foundation for predicting direct ecological effects of fires and fire-atmosphere coupling. Here, we focus on the relationships between the fire radiation field, as measured from the zenith, fuel consumption, and the behavior of spreading flame fronts. Experiments were conducted in 8 m x 8 m outdoor plots using pre-conditioned wildland fuels characteristic of mixed-oak forests of the eastern United States. Using dual-band radiometers with a field of view of about 18.5 m^2 at a height of 4.2 m, we found a near-linear increase in fire radiative energy density (FRED) over a range of fuel consumption between 0.15 kg m^-2 to 3.25 kg m^-2. Using an integrated heat budget, we estimate that the fraction of total theoretical combustion energy density radiated from the plot averaged 0.17, the fraction of latent energy transported in the plume averaged 0.08, and the fraction accounted for by the combination of fire convective energy transport and soil heating averaged 0.72. Future work will require, at minimum, instantaneous and time-integrated estimates of energy transported by radiation, convection, and soil heating across a range of fuels. We introduce the Rx-CADRE project through which such measurements are being made.

  11. Thermal stability of tungsten sub-nitride thin film prepared by reactive magnetron sputtering

    NASA Astrophysics Data System (ADS)

    Zhang, X. X.; Wu, Y. Z.; Mu, B.; Qiao, L.; Li, W. X.; Li, J. J.; Wang, P.

    2017-03-01

    Tungsten sub-nitride thin films deposited on silicon samples by reactive magnetron sputtering were used as a model system to study the phase stability and microstructural evolution during thermal treatments. XRD, SEM&FIB, XPS, RBS and TDS were applied to investigate the stability of tungsten nitride films after heating up to 1473 K in vacuum. At the given experimental parameters a 920 nm thick crystalline film with a tungsten and nitrogen stoichiometry of 2:1 were achieved. The results showed that no phase and microstructure change occurred due to W2N film annealing in vacuum up to 973 K. Heating up to 1073 K led to a partial decomposition of the W2N phase and the formation of a W enrichment layer at the surface. Increasing the annealing time at the same temperature, the further decomposition of the W2N phase was negligible. The complete decomposition of W2N film happened as the temperature reached up to 1473 K.

  12. CH₃NH₃PbI₃-based planar solar cells with magnetron-sputtered nickel oxide.

    PubMed

    Cui, Jin; Meng, Fanping; Zhang, Hua; Cao, Kun; Yuan, Huailiang; Cheng, Yibing; Huang, Feng; Wang, Mingkui

    2014-12-24

    Herein we report an investigation of a CH3NH3PbI3 planar solar cell, showing significant power conversion efficiency (PCE) improvement from 4.88% to 6.13% by introducing a homogeneous and uniform NiO blocking interlayer fabricated with the reactive magnetron sputtering method. The sputtered NiO layer exhibits enhanced crystallization, high transmittance, and uniform surface morphology as well as a preferred in-plane orientation of the (200) plane. The PCE of the sputtered-NiO-based perovskite p-i-n planar solar cell can be further promoted to 9.83% when a homogeneous and dense perovskite layer is formed with solvent-engineering technology, showing an impressive open circuit voltage of 1.10 V. This is about 33% higher than that of devices using the conventional spray pyrolysis of NiO onto a transparent conducting glass. These results highlight the importance of a morphology- and crystallization-compatible interlayer toward a high-performance inverted perovskite planar solar cell.

  13. Evaluation of SmCo and SmCoN magnetron sputtering coatings for SOFC interconnect applications

    NASA Astrophysics Data System (ADS)

    Wu, Junwei; Li, Chengming; Johnson, Christopher; Liu, Xingbo

    Cobalt or cobalt containing coatings are promising for SOFC interconnect applications because of their high conductivity. We have investigated SmCo and SmCoN coatings deposited by magnetron sputtering from a SmCo (5% Sm) target on to Crofer 22 APU substrates. The composition, structure, surface morphology, and electrical conductivity of the coated substrates were characterized by SEM/EDX, XRD and ASR measurements. Addition of Sm enhances the oxidation resistance and the Cr retention capability of the coatings. The use of nitride as a precursor stabilizes Sm during oxidation of the films, thus inhibiting diffusion of Fe, resulting in a more compact coating and lowering ASR. The combined advantages of Sm addition to cobalt and the use of a nitride as a precursor, makes SmCoN coatings a promising new interconnect coating material.

  14. Improvements on the stability and operation of a magnetron H - ion source

    DOE PAGES

    Sosa, A.; Bollinger, D. S.; Karns, P. R.; ...

    2017-05-31

    The magnetron H - ion sources developed in the 1970s currently in operation at Fermilab provide beam to the rest of the accelerator complex. A series of modifications to these sources have been tested in a dedicated offline test stand with the aim of improving different operational issues. The solenoid type gas valve was tested as an alternative to the piezoelectric gas valve in order to avoid its temperature dependence. A new cesium oven was designed and tested in order to avoid glass pieces that were present with the previous oven, improve thermal insulation and fine tune its temperature. Amore » current-regulated arc modulator was developed to run the ion source at a constant arc current, providing very stable beam outputs during operations. In order to reduce beam noise, the addition of small amounts of N 2 gas was explored, as well as testing different cathode shapes with increasing plasma volume. This study summarizes the studies and modifications done in the source over the last three years with the aim of improving its stability, reliability and overall performance.« less

  15. Corrosion studies of DC reactive magnetron sputtered alumina coating on 304 SS

    NASA Astrophysics Data System (ADS)

    Thangaraj, Baskar; Mahadevan, Krishnan

    2017-12-01

    Aluminum oxide films on SS 304 deposited by DC reactive magnetron sputtering technique were studied with respect to the composition of the sputter gas (Ar:O2), gas pressure, substrate temperature, current etc. to achieve good insulating films with high corrosion resistance. The films were characterized by XRD and SEM techniques. Potentiodynamic polarization and electrochemical impedance spectroscopy measurements were made under static conditions in order to evaluate the corrosion performance of the alumina-coated SS 304 for various immersion durations in 0.5 M and 1 M NaCl solution. Alumina-coated SS 304 has low corrosion value of 0.4550 and 1.1090MPY for 24 h immersion time in both solutions. The impedance plots for the alumina coated SS 304 in 1 M NaCl solution at different durations are slightly different to when compared to its immersion in 0.5 M NaCl solutions and are composed of two depressed semi circles. For the alumina coated film, the impedance spectrum decreased, when immersion time increased.

  16. Improvements on the stability and operation of a magnetron H- ion source

    NASA Astrophysics Data System (ADS)

    Sosa, A.; Bollinger, D. S.; Karns, P. R.; Tan, C. Y.

    2017-05-01

    The magnetron H- ion sources developed in the 1970s currently in operation at Fermilab provide beam to the rest of the accelerator complex. A series of modifications to these sources have been tested in a dedicated off-line test stand with the aim of improving different operational issues. The solenoid type gas valve was tested as an alternative to the piezoelectric gas valve in order to avoid its temperature dependence. A new cesium oven was designed and tested in order to avoid glass pieces that were present with the previous oven, improve thermal insulation and fine-tune its temperature. A current-regulated arc modulator was developed to run the ion source at a constant arc current, providing very stable beam outputs during operations. In order to reduce beam noise, the addition of small amounts of N2 gas was explored, as well as testing different cathode shapes with increasing plasma volume. This paper summarizes the studies and modifications done in the source over the past three years with the aim of improving its stability, reliability and overall performance.

  17. Improvements on the stability and operation of a magnetron H - ion source

    DOE Office of Scientific and Technical Information (OSTI.GOV)

    Sosa, A.; Bollinger, D. S.; Karns, P. R.

    The magnetron H - ion sources developed in the 1970s currently in operation at Fermilab provide beam to the rest of the accelerator complex. A series of modifications to these sources have been tested in a dedicated offline test stand with the aim of improving different operational issues. The solenoid type gas valve was tested as an alternative to the piezoelectric gas valve in order to avoid its temperature dependence. A new cesium oven was designed and tested in order to avoid glass pieces that were present with the previous oven, improve thermal insulation and fine tune its temperature. Amore » current-regulated arc modulator was developed to run the ion source at a constant arc current, providing very stable beam outputs during operations. In order to reduce beam noise, the addition of small amounts of N 2 gas was explored, as well as testing different cathode shapes with increasing plasma volume. This study summarizes the studies and modifications done in the source over the last three years with the aim of improving its stability, reliability and overall performance.« less

  18. Optical Field Confinement Enhanced Single ZnO Microrod UV Photodetector

    NASA Astrophysics Data System (ADS)

    Wei, Ming; Xu, Chun-Xiang; Qin, Fei-Fei; Gowri Manohari, Arumugam; Lu, Jun-Feng; Zhu, Qiu-Xiang

    2017-07-01

    ZnO microrods are synthesized using the vapor phase transport method, and the magnetron sputtering is used to decorate the Al nanoparticles (NPs) on a single ZnO microrod. The micro-PL and I-V responses are measured before and after the decoration of Al NPs. The FDTD stimulation is also carried out to demonstrate the optical field distribution around the decoration of Al NPs on the surface of a ZnO microrod. Due to an implementation of Al NPs, the ZnO microrod exhibits an improved photoresponse behavior. In addition, Al NPs induced localized surface plasmons (LSPs) as well as improved optical field confinement can be ascribed to an enhancement of ultraviolet (UV) response. This research provides a method for improving the responsivity of photodetectors. Supported by the National Natural Science Foundation of China under Grant Nos 61475035 and 61275054, the Science and Technology Support Program of Jiangsu Province under Grant No BE2016177, and the Collaborative Innovation Center of Suzhou Nano Science and Technology.

  19. Simulative and experimental investigation on stator winding turn and unbalanced supply voltage fault diagnosis in induction motors using Artificial Neural Networks.

    PubMed

    Lashkari, Negin; Poshtan, Javad; Azgomi, Hamid Fekri

    2015-11-01

    The three-phase shift between line current and phase voltage of induction motors can be used as an efficient fault indicator to detect and locate inter-turn stator short-circuit (ITSC) fault. However, unbalanced supply voltage is one of the contributing factors that inevitably affect stator currents and therefore the three-phase shift. Thus, it is necessary to propose a method that is able to identify whether the unbalance of three currents is caused by ITSC or supply voltage fault. This paper presents a feedforward multilayer-perceptron Neural Network (NN) trained by back propagation, based on monitoring negative sequence voltage and the three-phase shift. The data which are required for training and test NN are generated using simulated model of stator. The experimental results are presented to verify the superior accuracy of the proposed method. Copyright © 2015. Published by Elsevier Ltd.

  20. VALORATE: fast and accurate log-rank test in balanced and unbalanced comparisons of survival curves and cancer genomics.

    PubMed

    Treviño, Victor; Tamez-Pena, Jose

    2017-06-15

    The association of genomic alterations to outcomes in cancer is affected by a problem of unbalanced groups generated by the low frequency of alterations. For this, an R package (VALORATE) that estimates the null distribution and the P -value of the log-rank based on a recent reformulation is presented. For a given number of alterations that define the size of survival groups, the log-rank density is estimated by a weighted sum of conditional distributions depending on a co-occurrence term of mutations and events. The estimations are accurately accelerated by sampling across co-occurrences allowing the analysis of large genomic datasets in few minutes. In conclusion, the proposed VALORATE R package is a valuable tool for survival analysis. The R package is available in CRAN at https://cran.r-project.org and in http://bioinformatica.mty.itesm.mx/valorateR . vtrevino@itesm.mx. Supplementary data are available at Bioinformatics online. © The Author 2017. Published by Oxford University Press. All rights reserved. For Permissions, please e-mail: journals.permissions@oup.com