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Sample records for capacitively coupled binary

  1. Capacitively-coupled inductive sensor

    DOEpatents

    Ekdahl, Carl A.

    1984-01-01

    A capacitively coupled inductive shunt current sensor which utilizes capacitive coupling between flanges having an annular inductive channel formed therein. A voltage dividing capacitor is connected between the coupling capacitor and ground to provide immediate capacitive division of the output signal so as to provide a high frequency response of the current pulse to be detected. The present invention can be used in any desired outer conductor such as the outer conductor of a coaxial transmission line, the outer conductor of an electron beam transmission line, etc.

  2. Circuit Model for Capacitive Coupling in Inductively Coupled Plasmas

    NASA Astrophysics Data System (ADS)

    Watanabe, M.; Shaw, D. M.; Collins, G. J.; Sugai, H.

    1998-10-01

    A crude circuit model has been developed to illustrate and account for capacitive coupling between the rf coil and the bulk plasma in a stove top inductively coupled plasma source. The circuit model is composed of three levels of capacitance: the dielectric window capacitance, sheath capacitance contiguous to the dielectric window, and the chamber to ground sheath capacitance. The model is verified by quantitative comparison with the measured rf plasma potential in the bulk plasma body, plasma feedstock gas (argon) pressures below 2 mTorr. At higher pressures above 5 mTorr, the measured results diverge from the circuit model due to the transition from a spatially uniform electron density throughout the bulk plasma at pressures less than 2 mTorr to a less spatially uniform electron density at pressures above 5 mTorr.

  3. [Wireless ECG measurement system with capacitive coupling].

    PubMed

    Aleksandrowicz, Adrian; Walter, Marian; Leonhardt, Steffen

    2007-04-01

    This paper describes a measurement system that captures an electrocardiogram (ECG) using capacitively coupled electrodes. The measurement system was integrated into an off-the-shelf office chair (so-called "Aachen SmartChair"). Whereas for classical ECG measurement adhesive is used to attach conductively coupled electrodes to bare skin, the system presented allows ECG measurement through clothing without direct skin contact. Furthermore, a ZigBee communication module was integrated to allow wireless transmission of ECG data to a PC or an ICU patient monitor. For system validation, classical ECG using conductive electrodes was obtained simultaneously. First measurement results, including variations of cloth thickness and material, are presented and some of the system-specific problems of this approach are discussed.

  4. Kinetic simulations of magnetized capacitively coupled discharges

    NASA Astrophysics Data System (ADS)

    Trieschmann, Jan; Shihab, Mohammed; Eremin, Denis; Brinkmann, Ralf Peter; Schulze, Julian; Mussenbrock, Thomas

    2012-10-01

    Capacitive high frequency discharges are of crucial importance in the context of plasma etching, deposition and surface modification. As these single or multiple frequency discharges are oftentimes operated at low pressures of less than a few pascal, a high plasma density is commonly achieved with the use of external magnetic fields. In this work kinetic simulations are used to investigate the effect of inhomogeneous external magnetic fields on the discharge dynamics in a strongly nonlocal pressure regime. We found that capacitively coupled discharges can be largely asymmetrized by applying strong magnetic fields in front of a given target electrode. This not only has an effect on the plasma density, but also on the ion energy distribution functions (IEDF) at the electrodes and on the acceleration of fast electrons in the plasma sheath regions. In consequence in the discharge currents a generation of higher harmonics of the driving frequency can be observed. We investigate these scenarios in terms of 1D-3V Particle in Cell simulations.

  5. Rf capacitively-coupled electrodeless light source

    DOEpatents

    Manos, Dennis M.; Diggs, Jessie; Ametepe, Joseph D.; Fugitt, Jock A.

    2000-01-01

    An rf capacitively-coupled electrodeless light source is provided. The light source comprises a hollow, elongated chamber and at least one center conductor disposed within the hollow, elongated chamber. A portion of each center conductor extends beyond the hollow, elongated chamber. At least one gas capable of forming an electronically excited molecular state is contained within each center conductor. An electrical coupler is positioned concentric to the hollow, elongated chamber and the electrical coupler surrounds the portion of each center conductor that extends beyond the hollow, elongated chamber. A rf-power supply is positioned in an operable relationship to the electrical coupler and an impedance matching network is positioned in an operable relationship to the rf power supply and the electrical coupler.

  6. Electron heating in capacitively coupled plasmas revisited

    NASA Astrophysics Data System (ADS)

    Lafleur, T.; Chabert, P.; Booth, J. P.

    2014-06-01

    We revisit the problem of electron heating in capacitively coupled plasmas (CCPs), and propose a method for quantifying the level of collisionless and collisional heating in plasma simulations. The proposed procedure, based on the electron mechanical energy conservation equation, is demonstrated with particle-in-cell simulations of a number of single and multi-frequency CCPs operated in regimes of research and industrial interest. In almost all cases tested, the total electron heating is comprised of collisional (ohmic) and pressure heating parts. This latter collisionless component is in qualitative agreement with the mechanism of electron heating predicted from the recent re-evaluation of theoretical models. Finally, in very electrically asymmetric plasmas produced in multi-frequency discharges, we observe an additional collisionless heating mechanism associated with electron inertia.

  7. Instabilities in a capacitively coupled oxygen plasma

    SciTech Connect

    Küllig, C. Wegner, Th. Meichsner, J.

    2015-04-15

    Periodic fluctuations in the frequency range from 0.3 to 3 kHz were experimentally investigated in capacitively coupled radio frequency (13.56 MHz) oxygen plasma. The Gaussian beam microwave interferometry directly provides the line integrated electron density fluctuations. A system of two Langmuir probes measured the floating potential spatially (axial, radial) and temporally resolved. Hence, the floating potential fluctuation development is mapped within the discharge volume and provides a kind of discharge breathing and no wave propagation. Finally, it was measured the optical emission pattern of atomic oxygen during the fluctuation as well as the RF phase resolved optical emission intensity at selected phase position of the fluctuation by an intensified charge-coupled device camera. The deduced excitation rate pattern reveals the RF sheath dynamics and electron heating mechanisms, which is changing between low and high electronegativity during a fluctuation cycle. A perturbation calculation was taken into account using a global model with 15 elementary collision processes in the balance equations for the charged plasma species (O{sub 2}{sup +}, e, O{sup −}, O{sub 2}{sup −}) and a harmonic perturbation. The calculated frequencies agree with the experimentally observed frequencies. Whereby, the electron attachment/detachment processes are important for the generation of this instability.

  8. Instabilities in a capacitively coupled oxygen plasma

    NASA Astrophysics Data System (ADS)

    Küllig, C.; Wegner, Th.; Meichsner, J.

    2015-04-01

    Periodic fluctuations in the frequency range from 0.3 to 3 kHz were experimentally investigated in capacitively coupled radio frequency (13.56 MHz) oxygen plasma. The Gaussian beam microwave interferometry directly provides the line integrated electron density fluctuations. A system of two Langmuir probes measured the floating potential spatially (axial, radial) and temporally resolved. Hence, the floating potential fluctuation development is mapped within the discharge volume and provides a kind of discharge breathing and no wave propagation. Finally, it was measured the optical emission pattern of atomic oxygen during the fluctuation as well as the RF phase resolved optical emission intensity at selected phase position of the fluctuation by an intensified charge-coupled device camera. The deduced excitation rate pattern reveals the RF sheath dynamics and electron heating mechanisms, which is changing between low and high electronegativity during a fluctuation cycle. A perturbation calculation was taken into account using a global model with 15 elementary collision processes in the balance equations for the charged plasma species ( O2+, e , O-, O2- ) and a harmonic perturbation. The calculated frequencies agree with the experimentally observed frequencies. Whereby, the electron attachment/detachment processes are important for the generation of this instability.

  9. Gas heating mechanisms in capacitively coupled plasmas

    NASA Astrophysics Data System (ADS)

    Agarwal, Ankur; Rauf, Shahid; Collins, Ken

    2012-10-01

    Capacitively coupled plasma (CCP) tools utilized for plasma etching of dielectric features utilize large amounts of power for processing. As a result, neutral gas heats up significantly during processing. The resulting gas density variations across the reactor can affect reaction rates, radical densities, plasma characteristics and uniformity within the reactor. In this paper, results from a two-dimensional computational investigation of an Ar/CF4 CCP discharge incorporating an energy equation solution for all ions and neutrals are discussed. The dominant neutral gas heating process is identified to be elastic collisions with ions while conduction is found to be the major mechanism of heat transport. Some species such as F and CF3 demonstrate higher temperatures than the feedstock gases owing to additional heating via charge-exchange reactions and/or Franck-Condon heating. Typical process parameters such as pressure, frequency of excitation, power and gas composition are varied to investigate their impact on gas temperature. At higher excitation frequency and/or pressure, increased elastic collisions with ions lead to greater heat generation. The heat generated per molecule of the radicals, however, decreases with increase in pressure leading to a decrease in gas temperature. The increase in neutral collision frequencies with pressure also results in the decrease in temperature difference between species in the plasma. As CF4 fraction increases, both the elastic collision cross-section and Franck-Condon heating sources increase, leading to higher gas temperatures.

  10. Design Considerations in Capacitively Coupled Plasmas

    NASA Astrophysics Data System (ADS)

    Song, Sang-Heon; Ventzek, Peter; Ranjan, Alok

    2015-11-01

    Microelectronics industry has driven transistor feature size scaling from 10-6 m to 10-9 m during the past 50 years, which is often referred to as Moore's law. It cannot be overstated that today's information technology would not have been so successful without plasma material processing. One of the major plasma sources for the microelectronics fabrication is capacitively coupled plasmas (CCPs). The CCP reactor has been intensively studied and developed for the deposition and etching of different films on the silicon wafer. As the feature size gets to around 10 nm, the requirement for the process uniformity is less than 1-2 nm across the wafer (300 mm). In order to achieve the desired uniformity, the hardware design should be as precise as possible before the fine tuning of process condition is applied to make it even better. In doing this procedure, the computer simulation can save a significant amount of resources such as time and money which are critical in the semiconductor business. In this presentation, we compare plasma properties using a 2-dimensional plasma hydrodynamics model for different kinds of design factors that can affect the plasma uniformity. The parameters studied in this presentation include chamber accessing port, pumping port, focus ring around wafer substrate, and the geometry of electrodes of CCP.

  11. Wavelet approach to artifact noise removal from Capacitive coupled Electrocardiograph.

    PubMed

    Lee, Seung Min; Kim, Ko Keun; Park, Kwang Suk

    2008-01-01

    Capacitive coupled Electrocardiography (ECG) is introduced as non-invasive measurement technology for ubiquitous health care and appliance are spread out widely. Although it has many merits, however, capacitive coupled ECG is very weak for motion artifacts for its non-skin-contact property. There are many studies for artifact problems which treats all artifact signals below 0.8Hz. In our capacitive coupled ECG measurement system, artifacts exist not only below 0.8Hz but also over than 10Hz. Therefore, artifact noise removal algorithm using wavelet method is tested to reject artifact-wandered signal from measured signals. It is observed that using power calculation each decimation step, artifact-wandered signal is removed as low frequency artifacts as high frequency artifacts. Although some original ECG signal is removed with artifact signal, we could level the signal quality for long term measure which shows the best quality ECG signals as we can get. PMID:19163323

  12. Wavelet approach to artifact noise removal from Capacitive coupled Electrocardiograph.

    PubMed

    Lee, Seung Min; Kim, Ko Keun; Park, Kwang Suk

    2008-01-01

    Capacitive coupled Electrocardiography (ECG) is introduced as non-invasive measurement technology for ubiquitous health care and appliance are spread out widely. Although it has many merits, however, capacitive coupled ECG is very weak for motion artifacts for its non-skin-contact property. There are many studies for artifact problems which treats all artifact signals below 0.8Hz. In our capacitive coupled ECG measurement system, artifacts exist not only below 0.8Hz but also over than 10Hz. Therefore, artifact noise removal algorithm using wavelet method is tested to reject artifact-wandered signal from measured signals. It is observed that using power calculation each decimation step, artifact-wandered signal is removed as low frequency artifacts as high frequency artifacts. Although some original ECG signal is removed with artifact signal, we could level the signal quality for long term measure which shows the best quality ECG signals as we can get.

  13. Tunable capacitive coupling between two semiconductor charge qubits

    NASA Astrophysics Data System (ADS)

    Yu, Guo-Dong; Li, Hai-Ou; Cao, Gang; Xiao, Ming; Jiang, Hong-Wen; Guo, Guo-Ping

    2016-08-01

    Strong coupling between two qubits is one of the main requirements for high fidelity two-qubit logic operations. Here we experimentally investigate the capacitive coupling between two double quantum dots. A pair of open slot confinement gates is used to enhance the coupling. We find that the coupling energy J can be conveniently tuned in a broad range. Through numerical simulations, we study the effect of J on two-qubit operations. The analysis shows that our experimentally obtained J is adequate to achieve high fidelity two-qubit entanglement and logic gates.

  14. Tunable capacitive coupling between two semiconductor charge qubits.

    PubMed

    Yu, Guo-Dong; Li, Hai-Ou; Cao, Gang; Xiao, Ming; Jiang, Hong-Wen; Guo, Guo-Ping

    2016-08-12

    Strong coupling between two qubits is one of the main requirements for high fidelity two-qubit logic operations. Here we experimentally investigate the capacitive coupling between two double quantum dots. A pair of open slot confinement gates is used to enhance the coupling. We find that the coupling energy J can be conveniently tuned in a broad range. Through numerical simulations, we study the effect of J on two-qubit operations. The analysis shows that our experimentally obtained J is adequate to achieve high fidelity two-qubit entanglement and logic gates. PMID:27354414

  15. Capacitive-coupled Series Spoof Surface Plasmon Polaritons

    NASA Astrophysics Data System (ADS)

    Yin, Jia Yuan; Ren, Jian; Zhang, Hao Chi; Zhang, Qian; Cui, Tie Jun

    2016-04-01

    A novel method to realize stopband within the operating frequency of spoof surface plasmon polaritons (SPPs) is presented. The stopband is introduced by a new kind of capacitive-coupled series spoof SPPs. Two conventional H-shaped unit cells are proposed to construct a new unit cell, and every two new unit cells are separated by a gap with certain distance, which is designed to implement capacitive coupling. The original surface impedance matching is disturbed by the capacitive coupling, leading to the stopband during the transmission of SPPs. The proposed method is verified by both numerical simulations and experiments, and the simulated and measured results have good agreements. It is shown that the proposed structure exhibits a stopband in 9-9.5 GHz while the band-pass feature maintains in 5-9 GHz and 9.5-11 GHz. In the passband, the reflection coefficient is less than -10 dB, and the transmission loss is around 3 dB in the stopband, the reflection coefficient is -2 dB, and the transmission coefficient is less than -30 dB. The compact size, easy fabrication and good band-pass and band-stop features make the proposed structure a promising plasmonic device in SPP communication systems.

  16. Capacitive-coupled Series Spoof Surface Plasmon Polaritons

    PubMed Central

    Yin, Jia Yuan; Ren, Jian; Zhang, Hao Chi; Zhang, Qian; Cui, Tie Jun

    2016-01-01

    A novel method to realize stopband within the operating frequency of spoof surface plasmon polaritons (SPPs) is presented. The stopband is introduced by a new kind of capacitive-coupled series spoof SPPs. Two conventional H-shaped unit cells are proposed to construct a new unit cell, and every two new unit cells are separated by a gap with certain distance, which is designed to implement capacitive coupling. The original surface impedance matching is disturbed by the capacitive coupling, leading to the stopband during the transmission of SPPs. The proposed method is verified by both numerical simulations and experiments, and the simulated and measured results have good agreements. It is shown that the proposed structure exhibits a stopband in 9–9.5 GHz while the band-pass feature maintains in 5–9 GHz and 9.5–11 GHz. In the passband, the reflection coefficient is less than −10 dB, and the transmission loss is around 3 dB; in the stopband, the reflection coefficient is −2 dB, and the transmission coefficient is less than −30 dB. The compact size, easy fabrication and good band-pass and band-stop features make the proposed structure a promising plasmonic device in SPP communication systems. PMID:27089949

  17. Correlated Coulomb Drag in Capacitively Coupled Quantum-Dot Structures.

    PubMed

    Kaasbjerg, Kristen; Jauho, Antti-Pekka

    2016-05-13

    We study theoretically Coulomb drag in capacitively coupled quantum dots (CQDs)-a bias-driven dot coupled to an unbiased dot where transport is due to Coulomb mediated energy transfer drag. To this end, we introduce a master-equation approach that accounts for higher-order tunneling (cotunneling) processes as well as energy-dependent lead couplings, and identify a mesoscopic Coulomb drag mechanism driven by nonlocal multielectron cotunneling processes. Our theory establishes the conditions for a nonzero drag as well as the direction of the drag current in terms of microscopic system parameters. Interestingly, the direction of the drag current is not determined by the drive current, but by an interplay between the energy-dependent lead couplings. Studying the drag mechanism in a graphene-based CQD heterostructure, we show that the predictions of our theory are consistent with recent experiments on Coulomb drag in CQD systems.

  18. Electromechanical coupling factor of capacitive micromachined ultrasonic transducers

    NASA Astrophysics Data System (ADS)

    Caronti, Alessandro; Carotenuto, Riccardo; Pappalardo, Massimo

    2003-01-01

    Recently, a linear, analytical distributed model for capacitive micromachined ultrasonic transducers (CMUTs) was presented, and an electromechanical equivalent circuit based on the theory reported was used to describe the behavior of the transducer [IEEE Trans. Ultrason. Ferroelectr. Freq. Control 49, 159-168 (2002)]. The distributed model is applied here to calculate the dynamic coupling factor kw of a lossless CMUT, based on a definition that involves the energies stored in a dynamic vibration cycle, and the results are compared with those obtained with a lumped model. A strong discrepancy is found between the two models as the bias voltage increases. The lumped model predicts an increasing dynamic k factor up to unity, whereas the distributed model predicts a more realistic saturation of this parameter to values substantially lower. It is demonstrated that the maximum value of kw, corresponding to an operating point close to the diaphragm collapse, is 0.4 for a CMUT single cell with a circular membrane diaphragm and no parasitic capacitance (0.36 for a cell with a circular plate diaphragm). This means that the dynamic coupling factor of a CMUT is comparable to that of a piezoceramic plate oscillating in the thickness mode. Parasitic capacitance decreases the value of kw, because it does not contribute to the energy conversion. The effective coupling factor keff is also investigated, showing that this parameter coincides with kw within the lumped model approximation, but a quite different result is obtained if a computation is made with the more accurate distributed model. As a consequence, keff, which can be measured from the transducer electrical impedance, does not give a reliable value of the actual dynamic coupling factor.

  19. Is collisionless heating in capacitively coupled plasmas really collisionless?

    NASA Astrophysics Data System (ADS)

    Lafleur, T.; Chabert, P.

    2015-08-01

    By performing a combination of test-particle and particle-in-cell simulations, we investigate electron heating in single frequency capacitively coupled plasmas (CCPs). In agreement with previous theoretical considerations highlighted in Kaganovich et al (1996 Appl. Phys. Lett. 69 3818), we show that the level of true collisionless/stochastic heating in typical CCPs is significantly smaller than that due to collisional interactions; even at very low pressures and wide gap lengths. Fundamentally electron heating is a collisional phenomenon whereby particle collisions provide the vital phase randomization and stochastization mechanism needed to generate both a local (or ohmic) heating component, and a non-local (or hybrid) heating component.

  20. RF capacitively coupled plasma with multi-hole multi electrode

    NASA Astrophysics Data System (ADS)

    Lee, Hun Su; Lee, Yun Seong; Seo, Sang Hun; Chang, Hong Young

    2011-10-01

    In the photovoltaic industry, it is desired to make plasma discharge of high electron density for the deposition of microcrystalline silicon layer, which is a bottle-neck process in the fabrication of thin film solar cell. So multi-hole electrode instead of plane electrode is used to make capacitively coupled discharge and the deposition rate could be increased because of the plasma density increases by the increased ionization by the energetic secondary electron surrounded by sheath region. To further increase the productivity of the process, high frequency and large electrode area is demanded, however the uniformity of the process is degraded by the change. To solve the matter, the concept of dividing a multi-hole electrode into multiple multi-hole electrode is introduced in the presentation. By dividing electrode into several region and differentiating the hole configuration of each region, local hollow cathode effect can be controlled to make more uniform discharge. To verify the feasibility of the concept, an electrode of RF capacitively coupled plasma is divided and the hole configuration of each electrode. And with 13.56MHz power applied to the electrode, the spatial plasma distribution of the discharge is measured.

  1. Detection of Electrocardiogram by Electrodes with Fabrics Using Capacitive Coupling

    NASA Astrophysics Data System (ADS)

    Ueno, Akinori; Furusawa, Yoichi; Hoshino, Hiroshi; Ishiyama, Yoji

    This article reports on a novel technique for detecting electrocardiogram (ECG) at a condition where thin cloth is interpolated between sensing electrodes and the skin to which the electrodes are attached. The technique is based upon capacitive coupling composed of the electrode, the cloth and the skin, so that the electrode can lead alternating electrocardiographic current through capacitance of the coupling. The technique is also founded on impedance transforming circuit that has extremely high input impedance around 1000GΩ and low output impedance, so as to match high output impedance of the electrode to low input impedance required by subsequent circuitry. A pilot ECG measuring device was manufactured using the technique and experiments showed (1) ECG recordings using the device with silk of 240μm thickness or with cotton of 564μm thickness were quite similar to ECGs recorded from the skin using conventional system, (2) stable ECGs were observed with the silk below 600μm thickness or with the cotton below 1128μm thickness, (3) effects of long-term measurement and perspiration on ECG waveform were negligible. These results prove feasibility of the proposed technique for detecting ECG by electrodes with fabrics.

  2. Improving the gate fidelity of capacitively coupled spin qubits

    NASA Astrophysics Data System (ADS)

    Wang, Xin; Barnes, Edwin

    2015-03-01

    Precise execution of quantum gates acting on two or multiple qubits is essential to quantum computation. For semiconductor spin qubits coupled via capacitive interaction, the best fidelity for a two-qubit gate demonstrated so far is around 70%, insufficient for fault-tolerant quantum computation. In this talk we present control protocols that may substantially improve the robustness of two-qubit gates against both nuclear noise and charge noise. Our pulse sequences incorporate simultaneous dynamical decoupling protocols and are simple enough for immediate experimental realization. Together with existing control protocols for single-qubit gates, our results constitute an important step toward scalable quantum computation using spin qubits. This work is done in collaboration with Sankar Das Sarma and supported by LPS-NSA-CMTC and IARPA-MQCO.

  3. Double input capacitively coupled contactless conductivity detector with phase shift.

    PubMed

    Zheng, Hao; Li, Meng; Dai, Jianyuan; Wang, Zhen; Li, Xiuting; Yuan, Hongyan; Xiao, Dan

    2014-10-21

    A double input capacitively coupled contactless conductivity detector (DIC(4)D) device which gets higher sensitivity has been described in this paper. The detector consists of two input electrodes and one output electrode. When two alternating current (AC) voltages with the same amplitude and different phases are imposed on each input electrode, the equivalent resistance of the output electrode is reduced because of the interference of the two signals with different phase angles. For a capacitively coupled contactless conductivity detector (C(4)D), the ratio of the response of KCl solution to that of distilled water is 1.6. However, for DIC(4)D, the ratio is 1.55 at a phase difference of 0° and increases to 1.8 at the phase difference of 170°, respectively. For C(4)D, the response of KCl solution is a linear function of the logarithm of concentrations from 10(-5) M to 10(-2) M, and the slope is 5.58. However, the slope of the response increases to 7.13 in DIC(4)D, and the limit of detection (LOD) of DIC(4)D is estimated to be 5 × 10(-8) M. The slope of the three-way DIC(4)D is increased to 69.78. A flow injection device is employed for the evaluation of the applicability of DIC(4)D with the same range, and good reproducibility is confirmed through flow injection of the same solution 10 times. The relative standard deviation (RSD) is 0.7%, which demonstrates a promising application to capillary electrophoresis (CE).

  4. Acoustic coupling in capacitive microfabricated ultrasonic transducers: modeling and experiments.

    PubMed

    Caronti, Alessandro; Savoia, Alessandro; Caliano, Giosuè; Pappalardo, Massimo

    2005-12-01

    In the design of low-frequency transducer arrays for active sonar systems, the acoustic interactions that occur between the transducer elements have received much attention. Because of these interactions, the acoustic loading on each transducer depends on its position in the array, and the radiated acoustic power may vary considerably from one element to another. Capacitive microfabricated ultrasonic transducers (CMUT) are made of a two-dimensional array of metallized micromembranes, all electrically connected in parallel, and driven into flexural motion by the electrostatic force produced by an applied voltage. The mechanical impedance of these membranes is typically much lower than the acoustic impedance of water. In our investigations of acoustic coupling in CMUTs, interaction effects between the membranes in immersion were observed, similar to those reported in sonar arrays. Because CMUTs have many promising applications in the field of medical ultrasound imaging, understanding of cross-coupling mechanisms and acoustic interaction effects is especially important for reducing cross-talk between array elements, which can produce artifacts and degrade image quality. In this paper, we report a finite-element study of acoustic interactions in CMUTs and experimental results obtained by laser interferometry measurements. The good agreement found between finite element modeling (FEM) results and optical displacement measurements demonstrates that acoustic interactions through the liquid represent a major source of cross coupling in CMUTs.

  5. Capacitively Coupled Hot-Electron Nanobolometer with SIN Tunnel Junctions

    NASA Astrophysics Data System (ADS)

    Kuzmin, Leonid S.; Fominsky, M.; Kalabukhov, A.; Golubev, D.; Tarasov, M.

    2003-02-01

    A capacitively coupled hot-electron nanobolometer (CC-HEB) is the simplest and most effective antenna-coupled bolometer. The bolometer consists of a small absorber connected to the superconducting antenna by tunnel junctions. The tunnel junctions used for high-frequency coupling also give perfect thermal isolation of hot electrons in the small volume of the absorber. The same tunnel junctions are used for temperature measurements and electron cooling. This bolometer does not suffer from the frequency limitations in the submillimeter range due to the high potential barrier of the tunnel junctions as does the microbolometer with Andreev mirrors (A-HEB), which is limited by the superconducting gap. Theoretical analyses show that the two-junction configuration more than doubles the sensitivity of the bolometer in current-biased mode compared to the single-junction configuration used for A-HEB. Another important advantage of CC-HEB is its simple two-layer technology for sample fabrication. Samples were fabricated with an absorber made of a bilayer of Cr and Al to match the impedance of the antenna. Electrodes were made of Al and tunnel junctions were formed over the Al oxide layer. The coupling capacitances of the tunnel junctions, C ≍ 20 fF, in combination with the inductance of the 10 μm absorber create a bandpass filter with a central frequency around 300 GHz. Bolometers are integrated with log-periodic and double-dipole planar antennas made of Au. The temperature response of bolometer structures was measured at temperatures down to 256 mK. In our experiment we observed dV/dT=1.3 mV/K, corresponding to responsivity S=0.2.109 V/W. For amplifier noise Vna=3nV/Hz1/2 at 1 kHz the estimated total noise equivalent power is NEP=1.5.10-17 W/Hz1/2. The intrinsic bolometer self noise Vnbol=0.5 nV/Hz1/2 corresponds to NEP=3.10-18 W/Hz1/2. For microwave evaluation of bolometer sensitivity we used a black body radiation source comprising a thin NiCr stimulator placed on the

  6. Capacitively coupled hybrid pixel assemblies for the CLIC vertex detector

    NASA Astrophysics Data System (ADS)

    Tehrani, N. Alipour; Arfaoui, S.; Benoit, M.; Dannheim, D.; Dette, K.; Hynds, D.; Kulis, S.; Perić, I.; Petrič, M.; Redford, S.; Sicking, E.; Valerio, P.

    2016-07-01

    The vertex detector at the proposed CLIC multi-TeV linear e+e- collider must have minimal material content and high spatial resolution, combined with accurate time-stamping to cope with the expected high rate of beam-induced backgrounds. One of the options being considered is the use of active sensors implemented in a commercial high-voltage CMOS process, capacitively coupled to hybrid pixel ASICs. A prototype of such an assembly, using two custom designed chips (CCPDv3 as active sensor glued to a CLICpix readout chip), has been characterised both in the lab and in beam tests at the CERN SPS using 120 GeV/c positively charged hadrons. Results of these characterisation studies are presented both for single and dual amplification stages in the active sensor, where efficiencies of greater than 99% have been achieved at -60 V substrate bias, with a single hit resolution of 6.1 μm . Pixel cross-coupling results are also presented, showing the sensitivity to placement precision and planarity of the glue layer.

  7. Secondary electron induced asymmetry in capacitively coupled plasmas

    NASA Astrophysics Data System (ADS)

    Lafleur, T.; Chabert, P.; Booth, J. P.

    2013-04-01

    Using a simple analytical model, together with a 1D particle-in-cell simulation, we show that it is possible to generate an asymmetric plasma response in a sinusoidally excited, geometrically symmetric, capacitively coupled plasma (CCP). The asymmetric response is produced using rf electrodes of differing materials, and hence different secondary electron emission coefficients. This asymmetry in the emission coefficients can produce a significant, measurable dc bias voltage (Vbias/Vrf ˜ 0-0.2), together with an asymmetry in the plasma density profiles and ion flux to each electrode. The dc bias formation can be understood from a particle-flux balance applied to each electrode, and results from two main effects: (1) the larger effective ion flux at each electrode due to the emission of secondary electrons and (2) ion-flux multiplication within the sheath due to ionization from these emitted secondary electrons. By making use of an empirical fit to the simulation data, the possibility of non-invasively estimating secondary electron emission coefficients in CCP systems is discussed.

  8. Macroscopic quantum tunneling in a stack of capacitively-coupled intrinsic Josephson junctions

    NASA Astrophysics Data System (ADS)

    Koyama, Tomio; Machida, Masahiko

    2008-04-01

    A macroscopic quantum theory for the phase dynamics in capacitively-coupled intrinsic Josephson junctions (IJJ's) is constructed. We quantize the capacitively-coupled IJJ model in terms of the canonical quantization method. The multi-junction effect for the macroscopic quantum tunneling (MQT) to the first resistive branch is clarified. It is shown that the escape rate is greatly enhanced by the capacitive coupling between junctions. We also discuss the origin of the N2 -enhancement in the escape rate observed in the uniformly switching in Bi-2212 IJJ's.

  9. Macroscopic quantum effects in capacitively- and inductively-coupled intrinsic Josephson junctions

    NASA Astrophysics Data System (ADS)

    Koyama, T.; Machida, M.

    2009-03-01

    A theory for macroscopic quantum tunneling (MQT) in intrinsic Josephson junction stacks is formulated. Both capacitive and inductive couplings between junctions are taken into account. We calculate the escape rate in the switching to the first resistive branch in the quantum regime. It is shown that the enhancement of the escape rate is caused mainly by the capacitive coupling between junctions in IJJ's with small in-plane area of ~ 1μm2.

  10. Capacitively coupled RF voltage probe having optimized flux linkage

    DOEpatents

    Moore, James A.; Sparks, Dennis O.

    1999-02-02

    An RF sensor having a novel current sensing probe and a voltage sensing probe to measure voltage and current. The current sensor is disposed in a transmission line to link all of the flux generated by the flowing current in order to obtain an accurate measurement. The voltage sensor is a flat plate which operates as a capacitive plate to sense voltage on a center conductor of the transmission line, in which the measured voltage is obtained across a resistance leg of a R-C differentiator circuit formed by the characteristic impedance of a connecting transmission line and a capacitance of the plate, which is positioned proximal to the center conductor.

  11. Mapping Capacitive Coupling Among Pixels in a Sensor Array

    NASA Technical Reports Server (NTRS)

    Seshadri, Suresh; Cole, David M.; Smith, Roger M.

    2010-01-01

    An improved method of mapping the capacitive contribution to cross-talk among pixels in an imaging array of sensors (typically, an imaging photodetector array) has been devised for use in calibrating and/or characterizing such an array. The method involves a sequence of resets of subarrays of pixels to specified voltages and measurement of the voltage responses of neighboring non-reset pixels.

  12. Evaluation of electrical capacitance tomography sensor based on the coupling of fluid field and electrostatic field

    NASA Astrophysics Data System (ADS)

    Ye, Jiamin; Wang, Haigang; Yang, Wuqiang

    2016-07-01

    Electrical capacitance tomography (ECT) is based on capacitance measurements from electrode pairs mounted outside of a pipe or vessel. The structure of ECT sensors is vital to image quality. In this paper, issues with the number of electrodes and the electrode covering ratio for complex liquid-solids flows in a rotating device are investigated based on a new coupling simulation model. The number of electrodes is increased from 4 to 32 while the electrode covering ratio is changed from 0.1 to 0.9. Using the coupling simulation method, real permittivity distributions and the corresponding capacitance data at 0, 0.5, 1, 2, 3, 5, and 8 s with a rotation speed of 96 rotations per minute (rpm) are collected. Linear back projection (LBP) and Landweber iteration algorithms are used for image reconstruction. The quality of reconstructed images is evaluated by correlation coefficient compared with the real permittivity distributions obtained from the coupling simulation. The sensitivity for each sensor is analyzed and compared with the correlation coefficient. The capacitance data with a range of signal-to-noise ratios (SNRs) of 45, 50, 55 and 60 dB are generated to evaluate the effect of data noise on the performance of ECT sensors. Furthermore, the SNRs of experimental data are analyzed for a stationary pipe with permittivity distribution. Based on the coupling simulation, 16-electrode ECT sensors are recommended to achieve good image quality.

  13. Control of strong light-matter coupling using the capacitance of metamaterial nanocavities

    SciTech Connect

    Benz, Alexander; Campione, Salvatore; Klem, John Frederick; Sinclair, Michael B.; Brener, Igal

    2015-01-27

    Metallic nanocavities with deep subwavelength mode volumes can lead to dramatic changes in the behavior of emitters placed in their vicinity. The resulting collocation and interaction often leads to strong coupling. We present for the first time experimental evidence that the Rabi splitting is directly proportional to the electrostatic capacitance associated with the metallic nanocavity. As a result, the system analyzed consists of different metamaterial geometries with the same resonance wavelength coupled to intersubband transitions in quantum wells.

  14. A new technique for determining the capacitive coupling coefficients in flash EPROM's

    NASA Astrophysics Data System (ADS)

    San, K. T.; Kaya, Cetin; Liu, David K. Y.; Ma, Tso-Ping; Shah, Pradeep

    1992-06-01

    A new method to determine the capacitive coupling coefficients of flash EPROM's is presented. This technique relies on the Fowler-Nordheim (F-N) erase measurements and source/drain junction leakage characteristics of the device to extract the control gate, source, and drain coupling coefficients. An advantage offered by this method is its use of actual flash EPROM cell without requiring additional test structures.

  15. Control of strong light-matter coupling using the capacitance of metamaterial nanocavities.

    PubMed

    Benz, Alexander; Campione, Salvatore; Klem, John F; Sinclair, Michael B; Brener, Igal

    2015-03-11

    Metallic nanocavities with deep subwavelength mode volumes can lead to dramatic changes in the behavior of emitters placed in their vicinity. This collocation and interaction often leads to strong coupling. Here, we present for the first time experimental evidence that the Rabi splitting is directly proportional to the electrostatic capacitance associated with the metallic nanocavity. The system analyzed consists of different metamaterial geometries with the same resonance wavelength coupled to intersubband transitions in quantum wells.

  16. Capacitive coupling in hybrid graphene/GaAs nanostructures

    SciTech Connect

    Simonet, Pauline Rössler, Clemens; Krähenmann, Tobias; Varlet, Anastasia; Ihn, Thomas; Ensslin, Klaus; Reichl, Christian; Wegscheider, Werner

    2015-07-13

    Coupled hybrid nanostructures are demonstrated using the combination of lithographically patterned graphene on top of a two-dimensional electron gas (2DEG) buried in a GaAs/AlGaAs heterostructure. The graphene forms Schottky barriers at the surface of the heterostructure and therefore allows tuning the electronic density of the 2DEG. Conversely, the 2DEG potential can tune the graphene Fermi energy. Graphene-defined quantum point contacts in the 2DEG show half-plateaus of quantized conductance in finite bias spectroscopy and display the 0.7 anomaly for a large range of densities in the constriction, testifying to their good electronic properties. Finally, we demonstrate that the GaAs nanostructure can detect charges in the vicinity of the heterostructure's surface. This confirms the strong coupling of the hybrid device: localized states in the graphene ribbon could, in principle, be probed by the underlying confined channel. The present hybrid graphene/GaAs nanostructures are promising for the investigation of strong interactions and coherent coupling between the two fundamentally different materials.

  17. Mathematical modeling of intrinsic Josephson junctions with capacitive and inductive couplings

    NASA Astrophysics Data System (ADS)

    Rahmonov, I. R.; Shukrinov, Yu M.; Zemlyanaya, E. V.; Sarhadov, I.; Andreeva, O.

    2012-11-01

    We investigate the current voltage characteristics (CVC) of intrinsic Josephson junctions (IJJ) with two types of couplings between junctions: capacitive and inductive. The IJJ model is described by a system of coupled sine-Gordon equations which is solved numerically by the 4th order Runge-Kutta method. The method of numerical simulation and numerical results are presented. The magnetic field distribution is calculated as the function of coordinate and time at different values of the bias current. The influence of model parameters on the CVC is studied. The behavior of the IJJ in dependence on coupling parameters is discussed.

  18. The role of the relative voltage and phase for frequency coupling in a dual-frequency capacitively coupled plasma

    SciTech Connect

    O'Connell, D.; Gans, T.; Semmler, E.; Awakowicz, P.

    2008-08-25

    Frequency coupling in multifrequency discharges is a complex nonlinear interaction of the different frequency components. An alpha-mode low pressure rf capacitively coupled plasma operated simultaneously with two frequencies is investigated and the coupling of the two frequencies is observed to greatly influence the excitation and ionization within the discharge. Through this, plasma production and sustainment are dictated by the corresponding electron dynamics and can be manipulated through the dual-frequency sheath. These mechanisms are influenced by the relative voltage and also the relative phase of the two frequencies.

  19. A study on improvement of discharge characteristic by using a transformer in a capacitively coupled plasma

    SciTech Connect

    Kim, Young-Cheol; Kim, Hyun-Jun; Lee, Hyo-Chang; Chung, Chin-Wook

    2015-12-15

    In a plasma discharge system, the power loss at powered line, matching network, and other transmission line can affect the discharge characteristics such as the power transfer efficiency, voltage and current at powered electrode, and plasma density. In this paper, we propose a method to reduce power loss by using a step down transformer mounted between the matching network and the powered electrode in a capacitively coupled argon plasma. This step down transformer decreases the power loss by reducing the current flowing through the matching network and transmission line. As a result, the power transfer efficiency was increased about 5%–10% by using a step down transformer. However, the plasma density was dramatically increased compared to no transformer. This can be understood by the increase in ohmic heating and the decrease in dc-self bias. By simply mounting a transformer, improvement of discharge efficiency can be achieved in capacitively coupled plasmas.

  20. Nanocellulose coupled flexible polypyrrole@graphene oxide composite paper electrodes with high volumetric capacitance

    NASA Astrophysics Data System (ADS)

    Wang, Zhaohui; Tammela, Petter; Strømme, Maria; Nyholm, Leif

    2015-02-01

    A robust and compact freestanding conducting polymer-based electrode material based on nanocellulose coupled polypyrrole@graphene oxide paper is straightforwardly prepared via in situ polymerization for use in high-performance paper-based charge storage devices, exhibiting stable cycling over 16 000 cycles at 5 A g-1 as well as the largest specific volumetric capacitance (198 F cm-3) so far reported for flexible polymer-based electrodes.A robust and compact freestanding conducting polymer-based electrode material based on nanocellulose coupled polypyrrole@graphene oxide paper is straightforwardly prepared via in situ polymerization for use in high-performance paper-based charge storage devices, exhibiting stable cycling over 16 000 cycles at 5 A g-1 as well as the largest specific volumetric capacitance (198 F cm-3) so far reported for flexible polymer-based electrodes. Electronic supplementary information (ESI) available. See DOI: 10.1039/c4nr07251k

  1. Coupling capacitance between double quantum dots tunable by the number of electrons in Si quantum dots

    SciTech Connect

    Uchida, Takafumi Arita, Masashi; Takahashi, Yasuo; Fujiwara, Akira

    2015-02-28

    Tunability of capacitive coupling in the Si double-quantum-dot system is discussed by changing the number of electrons in quantum dots (QDs), in which the QDs are fabricated using pattern-dependent oxidation (PADOX) of a Si nanowire and multi-fine-gate structure. A single QD formed by PADOX is divided into multiple QDs by additional oxidation through the gap between the fine gates. When the number of electrons occupying the QDs is large, the coupling capacitance increases gradually and almost monotonically with the number of electrons. This phenomenon is attributed to the gradual growth in the effective QD size due to the increase in the number of electrons in the QDs. On the other hand, when the number of electrons changes in the few-electron regime, the coupling capacitance irregularly changes. This irregularity can be observed even up to 40 electrons. This behavior is attributable the rough structure of Si nano-dots made by PADOX. This roughness is thought to induce complicated change in the electron wave function when an electron is added to or subtracted from a QD.

  2. Strongly coupled polyaniline/graphene hybrids with much enhanced capacitance performance.

    PubMed

    Xi, Xin; Liu, Ruili; Huang, Tao; Xu, Yi; Wu, Dongqing

    2016-12-01

    To enforce the interactions between polyaniline (PANI) and graphene, a facile strategy is developed in this work to fabricate the strongly coupled hybrids of PANI nanofibers and graphene (named as PAGs) by introducing different diamines to functionalize graphene oxide. As the electrode material in a two-electrode supercapacitor (SC), the ethylenediamine-functionalized hybrid (PAG-EDA) deliveries an excellent volumetric specific capacitance of 810Fcm(-3) at 5mVs(-1). The SC also manifests high cycling stability by maintaining 84.4% of the initial capacitance after 10,000 cycles. More importantly, PAG-EDA renders the SC to have both high energy density (92.15Whkg(-1)) and high power density (182.28kWkg(-1)), superior to most of the previously reported PANI based SC electrode materials.

  3. Equidistance of branch structure in capacitively coupled Josephson junctions model with diffusion current

    NASA Astrophysics Data System (ADS)

    Shukrinov, Yu. M.; Mahfouzi, F.; Seidel, P.

    2006-11-01

    Branch structure in current-voltage characteristics of intrinsic Josephson junctions of HTSC is studied in the framework of two models: capacitively coupled Josephson junctions (CCJJ) model and CCJJ model with diffusion current (CCJJ + DC). We investigate the coupling dependence of the branch’s slopes and demonstrate that the equidistance of the branch structure in CCJJ model is broken at enough small values of coupling parameter (at α ≪ 1). We show that the inclusion of diffusion in the tunneling current through intrinsic Josephson junctions might restore the equidistance of the branch structure. Change of the current-voltage characteristics in CCJJ + DC model under variation of the coupling and McCumber parameters and effect of boundary conditions on the branch structure is analyzed.

  4. Coupled binary embedding for large-scale image retrieval.

    PubMed

    Zheng, Liang; Wang, Shengjin; Tian, Qi

    2014-08-01

    Visual matching is a crucial step in image retrieval based on the bag-of-words (BoW) model. In the baseline method, two keypoints are considered as a matching pair if their SIFT descriptors are quantized to the same visual word. However, the SIFT visual word has two limitations. First, it loses most of its discriminative power during quantization. Second, SIFT only describes the local texture feature. Both drawbacks impair the discriminative power of the BoW model and lead to false positive matches. To tackle this problem, this paper proposes to embed multiple binary features at indexing level. To model correlation between features, a multi-IDF scheme is introduced, through which different binary features are coupled into the inverted file. We show that matching verification methods based on binary features, such as Hamming embedding, can be effectively incorporated in our framework. As an extension, we explore the fusion of binary color feature into image retrieval. The joint integration of the SIFT visual word and binary features greatly enhances the precision of visual matching, reducing the impact of false positive matches. Our method is evaluated through extensive experiments on four benchmark datasets (Ukbench, Holidays, DupImage, and MIR Flickr 1M). We show that our method significantly improves the baseline approach. In addition, large-scale experiments indicate that the proposed method requires acceptable memory usage and query time compared with other approaches. Further, when global color feature is integrated, our method yields competitive performance with the state-of-the-arts.

  5. Coupled binary embedding for large-scale image retrieval.

    PubMed

    Zheng, Liang; Wang, Shengjin; Tian, Qi

    2014-08-01

    Visual matching is a crucial step in image retrieval based on the bag-of-words (BoW) model. In the baseline method, two keypoints are considered as a matching pair if their SIFT descriptors are quantized to the same visual word. However, the SIFT visual word has two limitations. First, it loses most of its discriminative power during quantization. Second, SIFT only describes the local texture feature. Both drawbacks impair the discriminative power of the BoW model and lead to false positive matches. To tackle this problem, this paper proposes to embed multiple binary features at indexing level. To model correlation between features, a multi-IDF scheme is introduced, through which different binary features are coupled into the inverted file. We show that matching verification methods based on binary features, such as Hamming embedding, can be effectively incorporated in our framework. As an extension, we explore the fusion of binary color feature into image retrieval. The joint integration of the SIFT visual word and binary features greatly enhances the precision of visual matching, reducing the impact of false positive matches. Our method is evaluated through extensive experiments on four benchmark datasets (Ukbench, Holidays, DupImage, and MIR Flickr 1M). We show that our method significantly improves the baseline approach. In addition, large-scale experiments indicate that the proposed method requires acceptable memory usage and query time compared with other approaches. Further, when global color feature is integrated, our method yields competitive performance with the state-of-the-arts. PMID:24951697

  6. Correlated Fluctuations in Strongly Coupled Binary Networks Beyond Equilibrium

    NASA Astrophysics Data System (ADS)

    Dahmen, David; Bos, Hannah; Helias, Moritz

    2016-07-01

    Randomly coupled Ising spins constitute the classical model of collective phenomena in disordered systems, with applications covering glassy magnetism and frustration, combinatorial optimization, protein folding, stock market dynamics, and social dynamics. The phase diagram of these systems is obtained in the thermodynamic limit by averaging over the quenched randomness of the couplings. However, many applications require the statistics of activity for a single realization of the possibly asymmetric couplings in finite-sized networks. Examples include reconstruction of couplings from the observed dynamics, representation of probability distributions for sampling-based inference, and learning in the central nervous system based on the dynamic and correlation-dependent modification of synaptic connections. The systematic cumulant expansion for kinetic binary (Ising) threshold units with strong, random, and asymmetric couplings presented here goes beyond mean-field theory and is applicable outside thermodynamic equilibrium; a system of approximate nonlinear equations predicts average activities and pairwise covariances in quantitative agreement with full simulations down to hundreds of units. The linearized theory yields an expansion of the correlation and response functions in collective eigenmodes, leads to an efficient algorithm solving the inverse problem, and shows that correlations are invariant under scaling of the interaction strengths.

  7. Development and Application of Capacitive Coupling Voltage Contrast for Microelectronic Analysis.

    NASA Astrophysics Data System (ADS)

    Cole, Edward Issac, Jr.

    A scanning electron microscope was used to examine dynamic secondary electron emission from the surface of microelectronic structures. This dynamic secondary electron emission, called capacitive coupling voltage contrast, occurs only at low primary electron beam energies. Low energies minimize radiation damage to sensitive structures and make non-destructive electron beam analysis possible. By examining the temporal dependence of the secondary electron emission, a method for determining the potential of buried structures through an insulating surface passivation has been developed. Voltage measurements with a standard error of 45 mV or lower have been obtained, which exceeds the resolution of currently used energy spectrometers. In addition, the depth of buried structures under passivation was determined from the dynamic secondary electron emission. Applied bias is not necessary for depth profiling, alleviating the need for mechanical probing and/or wire bonding of the sample. An average error of 6.59%, with a standard deviation of 4.93%, has been obtained over a depth range from 0.04 to 0.76 micrometers. While not as accurate as ellipsometry, the definable area of interest can be 5 orders of magnitude smaller than is possible with optical techniques. Further, a method for producing capacitive coupling voltage contrast images of buried, unbiased structures was developed, with better than one micrometer spatial resolution through passivation. An electron beam/device interaction model was developed to interpret the experimental results.

  8. Numerical investigation on electrical characterization of a capacitive coupled radio-frequency plasma

    NASA Astrophysics Data System (ADS)

    Yao, H.; He, X.; Chen, J. P.; Zhang, Y. C.

    2015-05-01

    This paper presents the main electrical features of capacitive coupled radio-frequency (CCRF) discharges in gas. A two-dimensional, time-dependent fluid model was established. Capacitive coupled plasmas (CCP) were produced by applying radio-frequency voltage to a pair of parallel plate electrodes which are separated from the plasma by dielectric layers. The electron equation and the electron transport equations were solved and yielded the electron number density and electron temperature. The electrostatic field was obtained by the solution of the Poisson equation. The distribution of electron temperature and electron number density was studied under different conditions: radio-frequency applied voltages (VRF=100-2000V), frequencies (f=3.0-40.68MHz), pressures (p=0.001-1torr), and gas species (O2, Ar, He, N2). The results show that electron number density presents a minimum near the electrodes, and presents a maximum between the positive and the negative electrodes. The distinguishing feature of CCP is the presence of oscillating sheaths near electrodes where displacement current dominates conduction current. These informations will help us to analyze the characters of CCP for application.

  9. Pneumatic switched angle spinning NMR probe with capacitively coupled double saddle coil.

    PubMed

    Litvak, Ilya M; Espinosa, Catalina A; Shapiro, Rebecca A; Oldham, Andrew N; Duong, Vincent V; Martin, Rachel W

    2010-10-01

    Switched angle spinning (SAS) experiments can be used for generating isotropic-anisotropic correlations in oriented samples in a single experiment. In order for these methods to become widespread, specialized hardware is required. Here we describe the electronic and mechanical design and performance of a double-resonance SAS probe. Unlike many previous SAS probe implementations, the focus here is on systems where the dipolar couplings are partially averaged by molecular motion. This probe has a moving double saddle coil capacitively coupled to the stationary circuit. Angle switching is accomplished by a steam engine-type pneumatic mechanism. The speed and stability of the switching hardware for SAS experiments are demonstrated using spectra of model compounds. PMID:20673643

  10. Active loaded plasmonic antennas at terahertz frequencies: Optical control of their capacitive-inductive coupling

    NASA Astrophysics Data System (ADS)

    Georgiou, G.; Tserkezis, C.; Schaafsma, M. C.; Aizpurua, J.; Gómez Rivas, J.

    2015-03-01

    We demonstrate the photogeneration of loaded dipole plasmonic antennas resonating at THz frequencies. This is achieved by the patterned optical illumination of a semiconductor surface using a spatial light modulator. Our experimental results indicate the existence of capacitive and inductive coupling of localized surface plasmon polaritons. By varying the load in the antenna gap we are able to switch between both coupling regimes. Furthermore, we determine experimentally the effective impedance of the antenna load and verify that this load can be effectively expressed as a LC resonance formed by a THz inductor and capacitor connected in a parallel circuit configuration. These findings are theoretically supported by full electrodynamic calculations and by simple concepts of lumped circuit theory. Our results open new possibilities for the design of active THz circuits for optoelectronic devices.

  11. Pneumatic switched angle spinning NMR probe with capacitively coupled double saddle coil.

    PubMed

    Litvak, Ilya M; Espinosa, Catalina A; Shapiro, Rebecca A; Oldham, Andrew N; Duong, Vincent V; Martin, Rachel W

    2010-10-01

    Switched angle spinning (SAS) experiments can be used for generating isotropic-anisotropic correlations in oriented samples in a single experiment. In order for these methods to become widespread, specialized hardware is required. Here we describe the electronic and mechanical design and performance of a double-resonance SAS probe. Unlike many previous SAS probe implementations, the focus here is on systems where the dipolar couplings are partially averaged by molecular motion. This probe has a moving double saddle coil capacitively coupled to the stationary circuit. Angle switching is accomplished by a steam engine-type pneumatic mechanism. The speed and stability of the switching hardware for SAS experiments are demonstrated using spectra of model compounds.

  12. Pneumatic switched angle spinning NMR probe with capacitively coupled double saddle coil

    NASA Astrophysics Data System (ADS)

    Litvak, Ilya M.; Espinosa, Catalina A.; Shapiro, Rebecca A.; Oldham, Andrew N.; Duong, Vincent V.; Martin, Rachel W.

    2010-10-01

    Switched angle spinning (SAS) experiments can be used for generating isotropic-anisotropic correlations in oriented samples in a single experiment. In order for these methods to become widespread, specialized hardware is required. Here we describe the electronic and mechanical design and performance of a double-resonance SAS probe. Unlike many previous SAS probe implementations, the focus here is on systems where the dipolar couplings are partially averaged by molecular motion. This probe has a moving double saddle coil capacitively coupled to the stationary circuit. Angle switching is accomplished by a steam engine-type pneumatic mechanism. The speed and stability of the switching hardware for SAS experiments are demonstrated using spectra of model compounds.

  13. Coupling of Waveguide and Resonator by Inductive and Capacitive Irises for EPR Spectroscopy

    PubMed Central

    Mett, R.R.; Sidabras, J.W.; Hyde, J.S.

    2009-01-01

    An analytic circuit model for slot coupling from a waveguide to a loop-gap resonator (LGR) in a context of electron paramagnetic resonance (EPR) spectroscopy is presented. The physical dimensions of the waveguide, iris, LGR, and aqueous sample are transformed into circuit values of inductance, capacitance, and resistance. These values are used in a solution of circuit equations that results in a prediction of the rf currents, magnitude and phase, frequency, and magnetic and electric stored energies near critical coupling. The circuit geometry reflects magnetic flux conservation between the iris and LGR as well as modification of the outer loop LGR currents by the iris. Unlike conventional models, coupling is not explicitly based on a mutual inductance between the iris and LGR. Instead, the conducting wall high frequency rf boundary condition is used to define surface currents, regions, and circuit topology with lumped-circuit values of self-inductance, capacitance, and resistance. Match is produced by a combination of self-inductive and capacitive circuit coupling. Two conditions must be met to achieve match. First, the equivalent resistance of the LGR as seen by the iris must be transformed into the waveguide characteristic impedance. This transformation is met at a particular frequency relative to the natural LGR resonance frequency. The frequency shift magnitude is largely determined by the LGR properties, weakly dependent on iris length and placement, and independent of other iris dimensions. The second condition for match is that the iris reactance at this frequency shift must cancel the residual reactance of the LGR. This second condition is sensitive to the iris dimensions. If both conditions are not simultaneously satisfied, overcoupling or undercoupling results. A slotted iris of equal length to the size of the large dimension of the waveguide is found to have many properties opposite to a conventional iris of shorter length. Notably, the magnetic field

  14. Emissive Probe Measurements in a Dual-Frequency-Confined Capacitively-Coupled-Plasma System

    NASA Astrophysics Data System (ADS)

    Linnane, Shane; Ellingboe, Albert R.

    2002-10-01

    Dual frequency confined capacitively coupled plasmas (DFC-CCP) are increasingly used in semiconductor manufacturing for dielectric etching, allowing greater (and independent) control of ion energies and ion flux on the etched substrate. The powered electrode is driven with the summation of 27MHz and 2MHz sinusoidal voltages, while the other electrode is grounded. The electrode areas are similar in size, giving an electrode aspect ratio less than 2. Because of this low aspect ratio, there are large oscillations in the plasma potential. The expectation is for sinusoidal oscillations at the higher driving frequency, due to capacitive sheaths, while a rectified oscillation is expected at the lower driving frequency.(E. Kawamura, V. Vahedi, M. A. Lieberman and C. K. Birdsall, Plasma Sources Sci. Technology. 8 (1999) R45-R64 Work Supported by EURATOM.) Measurements of rf oscillation in the plasma potential taken with a floating emissive probe will be presented. The emissive probe and circuitry allows direct realtime measurement of plasma potential oscillation at both driving frequencies and the harmonics of each, thus allowing measurement of the actual potential on the driven electrode and ion energy incident on grounded electrode.

  15. Tumor Selective Hyperthermia Induced by Short-Wave Capacitively-Coupled RF Electric-Fields

    PubMed Central

    Raoof, Mustafa; Cisneros, Brandon T.; Corr, Stuart J.; Palalon, Flavio; Curley, Steven A.; Koshkina, Nadezhda V.

    2013-01-01

    There is a renewed interest in developing high-intensity short wave capacitively-coupled radiofrequency (RF) electric-fields for nanoparticle-mediated tumor-targeted hyperthermia. However, the direct thermal effects of such high-intensity electric-fields (13.56 MHZ, 600 W) on normal and tumor tissues are not completely understood. In this study, we investigate the heating behavior and dielectric properties of normal mouse tissues and orthotopically-implanted human hepatocellular and pancreatic carcinoma xenografts. We note tumor-selective hyperthermia (relative to normal mouse tissues) in implanted xenografts that can be explained on the basis of differential dielectric properties. Furthermore, we demonstrate that repeated RF exposure of tumor-bearing mice can result in significant anti-tumor effects compared to control groups without detectable harm to normal mouse tissues. PMID:23861912

  16. Observation of transient electric fields in particle-in-cell simulation of capacitively coupled discharges

    SciTech Connect

    Sharma, S. Mishra, S. K.; Kaw, Predhiman K.

    2014-07-15

    The analytical prediction of the presence of transient electric field regions between the bulk plasma and sheath edge in radio frequency capacitively coupled plasma (RF-CCP) discharges has been reported by Kaganovich [Phys. Rev. Lett. 89, 265006 (2002)]. In this paper, we have used the semi-infinite particle-in-cell (PIC) simulation technique to verify the theoretical prediction for the existence of transient electric field in the linear regime; it is shown that the PIC simulation results are in good agreement with the results predicted by analytical model in this regime. It is also demonstrated that the linear theory overestimates the transient electric field as one moves from linear to weakly nonlinear regime. The effect of applied RF current density and electron temperature on evolution of transition field and phase mixing regime has been explored.

  17. Direct current dielectric barrier assistant discharge to get homogeneous plasma in capacitive coupled discharge

    SciTech Connect

    Du, Yinchang; Li, Yangfang; Cao, Jinxiang; Liu, Yu; Wang, Jian; Zheng, Zhe

    2014-06-15

    In this paper, we propose a method to get more homogeneous plasma in the geometrically asymmetric capacitive coupled plasma (CCP) discharge. The dielectric barrier discharge (DBD) is used for the auxiliary discharge system to improve the homogeneity of the geometrically asymmetric CCP discharge. The single Langmuir probe measurement shows that the DBD can increase the electron density in the low density volume, where the DBD electrodes are mounted, when the pressure is higher than 5 Pa. By this manner, we are able to improve the homogeneity of the plasma production and increase the overall density in the target volume. At last, the finite element simulation results show that the DC bias, applied to the DBD electrodes, can increase the homogeneity of the electron density in the CCP discharge. The simulation results show a good agreement with the experiment results.

  18. Kinetic simulation of capacitively coupled plasmas driven by trapezoidal asymmetric voltage pulses

    SciTech Connect

    Diomede, Paola Economou, Demetre J.

    2014-06-21

    A kinetic Particle-In-Cell simulation with Monte Carlo Collisions was performed of a geometrically symmetric capacitively coupled, parallel-plate discharge in argon, driven by trapezoidal asymmetric voltage pulses with a period of 200 ns. The discharge was electrically asymmetric, making the ion energy distributions at the two electrodes different from one another. The fraction of the period (α), during which the voltage was kept at a constant (top-flat) positive value, was a critical control parameter. For the parameter range investigated, as α increased, the mean ion energy on the grounded electrode increased and the ions became more directional, whereas the opposite was found for the ions striking the powered electrode. The absolute value of the DC self-bias voltage decreased as α increased. Plasma instabilities, promoted by local double layers and electric field reversals during the time of the positive voltage excursion, were characterized by electron plasma waves launched from the sheath edge.

  19. Diffusion Dynamics of Charged Dust Particles in Capacitively Coupled RF Discharge System

    SciTech Connect

    Chew, W. X.; Muniandy, S. V.; Wong, C. S.; Yap, S. L.; Tan, K. S.

    2011-03-30

    Dusty plasma is loosely defined as electron-ion plasma with additional charged components of micron-sized dust particles. In this study, we developed a particle diagnostic technique based on light scattering and particle tracking velocimetry to investigate the dynamics of micron-sized titanium oxide particles in Argon gas capacitively coupled rf-discharge. The particle trajectories are constructed from sequence of image frames and treated as sample paths of charged Brownian motion. At specific sets of plasma parameters, disordered liquid-like dust particle configuration are observed. Mean-square-displacement of the particle trajectories are determined to characterize the transport dynamics. We showed that the dust particles in disordered liquid phase exhibit anomalous diffusion with different scaling exponents for short and large time scales, indicating the presence of slow and fast modes which can be related to caging effect and dispersive transport, respectively.

  20. Frequency dependent plasma characteristics in a capacitively coupled 300 mm wafer plasma processing chamber.

    SciTech Connect

    Hebner, Gregory Albert; Holland, J.P.; Paterson, A.M.; Barnat, Edward V.; Miller, Paul Albert

    2006-01-01

    Argon plasma characteristics in a dual-frequency, capacitively coupled, 300 mm-wafer plasma processing system were investigated for rf drive frequencies between 10 and 190 MHz. We report spatial and frequency dependent changes in plasma parameters such as line-integrated electron density, ion saturation current, optical emission and argon metastable density. For the conditions investigated, the line-integrated electron density was a nonlinear function of drive frequency at constant rf power. In addition, the spatial distribution of the positive ions changed from uniform to peaked in the centre as the frequency was increased. Spatially resolved optical emission increased with frequency and the relative optical emission at several spectral lines depended on frequency. Argon metastable density and spatial distribution were not a strong function of drive frequency. Metastable temperature was approximately 400 K.

  1. Real-time control of electron density in a capacitively coupled plasma

    SciTech Connect

    Keville, Bernard; Gaman, Cezar; Turner, Miles M.; Zhang Yang; Daniels, Stephen; Holohan, Anthony M.

    2013-05-15

    Reactive ion etching (RIE) is sensitive to changes in chamber conditions, such as wall seasoning, which have a deleterious effect on process reproducibility. The application of real time, closed loop control to RIE may reduce this sensitivity and facilitate production with tighter tolerances. The real-time, closed loop control of plasma density with RF power in a capacitively coupled argon plasma using a hairpin resonance probe as a sensor is described. Elementary control analysis shows that an integral controller provides stable and effective set point tracking and disturbance attenuation. The trade off between performance and robustness may be quantified in terms of one parameter, namely the position of the closed loop pole. Experimental results are presented, which are consistent with the theoretical analysis.

  2. Kinetic simulation of capacitively coupled plasmas driven by trapezoidal asymmetric voltage pulses

    NASA Astrophysics Data System (ADS)

    Diomede, Paola; Economou, Demetre J.

    2014-06-01

    A kinetic Particle-In-Cell simulation with Monte Carlo Collisions was performed of a geometrically symmetric capacitively coupled, parallel-plate discharge in argon, driven by trapezoidal asymmetric voltage pulses with a period of 200 ns. The discharge was electrically asymmetric, making the ion energy distributions at the two electrodes different from one another. The fraction of the period (α), during which the voltage was kept at a constant (top-flat) positive value, was a critical control parameter. For the parameter range investigated, as α increased, the mean ion energy on the grounded electrode increased and the ions became more directional, whereas the opposite was found for the ions striking the powered electrode. The absolute value of the DC self-bias voltage decreased as α increased. Plasma instabilities, promoted by local double layers and electric field reversals during the time of the positive voltage excursion, were characterized by electron plasma waves launched from the sheath edge.

  3. Effects of gas pressure on 60/13.56 MHz dual-frequency capacitively coupled plasmas

    SciTech Connect

    Yuan, Q. H.; Yin, G. Q.; Xin, Y.; Ning, Z. Y.

    2011-05-15

    The electron energy probability functions (EEPFs) were measured with increasing gas pressure in 60/13.56 MHz dual-frequency capacitively coupled plasma (DF-CCP) using compensated Langmiur electrostatic probe. The transition pressure of heating mode from collisionless to collisional heating in 60/13.56 MHz DF-CCP is found to be significantly lower than that in 13.56 MHz single-frequency CCP. As the pressure increases, the EEPFs change from bi-Maxwellian to Druyvesteyn type which is similar with that in 60 MHz single-frequency CCP. The pressure dependence of electron densities, effective electron temperatures, floating potentials, and plasma potentials in 60/13.56 MHz DF-CCP were measured and were compared with that in 60 MHz single-frequency CCP. The pressure dependence of these plasma parameters in 60/13.56 MHz DF-CCP is similar with that in 60 MHz single-frequency CCP.

  4. Ion transit through capacitively coupled Ar sheaths: Ion current and energy distribution

    NASA Astrophysics Data System (ADS)

    Greene, W. M.; Hartney, M. A.; Oldham, W. G.; Hess, D. W.

    1988-03-01

    The ion current and ion energy distribution (IED) of Ar+ and ArH+ impinging on a grounded surface immersed in capacitively coupled Ar plasmas have been measured as a function of pressure, applied rf voltage amplitude (Vrf), interelectrode gap, and sampling orifice size. A maximum in ion current occurs at high Vrf and intermediate electrode spacing. rf modulation of the collisionless IED occurs at high pressure and high Vrf and is caused by reduction of the sheath dimension under these conditions. Collisional shift to lower ion energy is also noted at high pressure. A low-energy peak at ˜10 eV is observed under high pressure and ion current conditions. Larger orifice sizes increase the collisions occurring downstream from the orifice as indicated by collisional energy shifts in the IED and a decrease in ion current density.

  5. Simulation of dust particles in dual-frequency capacitively coupled silane discharges

    SciTech Connect

    Liu Xiangmei; Song Yuanhong; Xu Xiang; Wang Younian

    2010-01-15

    The behavior of nanoparticles in dual-frequency capacitively coupled silane discharges is investigated by employing a one-dimensional self-consistent fluid model. The numerical simulation tries to trace the formation, charging, growth, and transport of dust particles during the discharge, under the influences of the high- and low-frequency electric sources, as well as the gas pressure. The effects of the presence of the nanoparticles and larger anions on the plasma properties are also discussed, especially, for the bulk potential, electron temperature, and densities of various particles. The calculation results show that the nanoparticle density and charge distribution are mainly influenced by the voltage and frequency of the high-frequency source, while the voltage of the low-frequency source can also exert an effect on the nanoparticle formation, compared with the frequency. As the discharge lasts, the electric potential and electron density keep decreasing, while the electron temperature gets increasing after a sudden drop.

  6. Numerical Study of a System of Long Josephson Junctions with Inductive and Capacitive Couplings

    NASA Astrophysics Data System (ADS)

    Rahmonov, I. R.; Shukrinov, Yu. M.; Plecenik, A.; Zemlyanaya, E. V.; Bashashin, M. V.

    2016-02-01

    The phase dynamics of the stacked long Josephson junctions is investigated taking into account the inductive and capacitive couplings between junctions and the diffusion current. The simulation of the current-voltage characteristics is based on the numerical solution of a system of nonlinear partial differential equations by a fourth order Runge-Kutta method and finite-difference approximation. A parallel implementation is based on the MPI technique. The effectiveness of the MPI/C++ code is confirmed by calculations on the multi-processor cluster CICC (LIT JINR, Dubna). We demonstrate the appearance of the charge traveling wave (CTW) at the boundary of the zero field step. Based on this fact, we conclude that the CTW and the fluxons coexist.

  7. Abnormal heating of low-energy electrons in low-pressure capacitively coupled discharges.

    PubMed

    Park, G Y; You, S J; Iza, F; Lee, J K

    2007-02-23

    In low-pressure capacitively coupled plasmas, high-energy electrons are collisionlessly heated by large rf fields in the sheaths while low-energy electrons are confined in the bulk plasma by the ambipolar potential. Low-energy electrons are typically inefficiently heated due to their low collisionality and the weak rf electric field present in the bulk. It is shown, however, that as a result of the nonlinear interaction between the electron motion and the weak rf field present in the bulk, low-energy electrons can be efficiently heated. Electrons in the bulk that bounce inside the electrostatic potential well with a frequency equal to the rf excitation frequency are efficiently heated by the coherent interaction with the rf field. This resonant collisionless heating can be very efficient and manifest itself as a plateau in the electron energy probability function.

  8. Capacitively coupled singlet-triplet qubits in the double charge resonant regime

    NASA Astrophysics Data System (ADS)

    Srinivasa, V.; Taylor, J. M.

    2015-12-01

    We investigate a method for entangling two singlet-triplet qubits in adjacent double quantum dots via capacitive interactions. In contrast to prior work, here we focus on a regime with strong interactions between the qubits. The interplay of the interaction energy and simultaneous large detunings for both double dots gives rise to the "double charge resonant" regime, in which the unpolarized (1111) and fully polarized (0202) four-electron states in the absence of interqubit tunneling are near degeneracy, while being energetically well separated from the partially polarized (0211 and 1102) states. A rapid controlled-phase gate may be realized by combining time evolution in this regime in the presence of intraqubit tunneling and the interqubit Coulomb interaction with refocusing π pulses that swap the singly occupied singlet and triplet states of the two qubits via, e.g., magnetic gradients. We calculate the fidelity of this entangling gate, incorporating models for two types of noise—charge fluctuations in the single-qubit detunings and charge relaxation within the low-energy subspace via electron-phonon interaction—and identify parameter regimes that optimize the fidelity. The rates of phonon-induced decay for pairs of GaAs or Si double quantum dots vary with the sizes of the dipolar and quadrupolar contributions and are several orders of magnitude smaller for Si, leading to high theoretical gate fidelities for coupled singlet-triplet qubits in Si dots. We also consider the dependence of the capacitive coupling on the relative orientation of the double dots and find that a linear geometry provides the fastest potential gate.

  9. Metalless electrodes for capacitively coupled contactless conductivity detection on electrophoresis microchips.

    PubMed

    Duarte Junior, Gerson F; Fracassi da Silva, José Alberto; Mendonça Francisco, Kelliton José; do Lago, Claudimir Lucio; Carrilho, Emanuel; Coltro, Wendell K T

    2015-08-01

    This paper describes the use of ionic solutions as sensing electrodes for capacitively coupled contactless conductivity detection on electrophoresis microchips. Initially, two channels were engraved in a PMMA holder by using a CO2 laser system and sealed with a thin adhesive membrane. PDMS electrophoresis chips were fabricated by soft lithography and reversibly sealed against the polymer membrane. Different ionic solutions were investigated as metalless electrodes. The electrode channels were filled with KCl solutions prepared in conductivity values from approximately 10 to 40 S/m. The best analytical response was achieved using the KCl solution with 21.9 S/m conductivity (2 mol/L). Besides KCl, we also tested NaCl and LiCl solutions for actuating as detection electrodes. Taking into account the same electrolyte concentration (2 mol/L), the best response was recorded with KCl solution due to its higher ionic conductivity. The optimum operating frequency (400 kHz) and the best sensing electrode (2 mol/L KCl) were used to monitor electrophoretic separations of a mixture containing K(+) , Na(+) , and Li(+) . The use of liquid solutions as sensing electrodes for capacitively coupled contactless conductivity detection measurements has revealed great performance to monitor separations on chip-based devices, avoiding complicated fabrication schemes to include metal deposition and encapsulation of electrodes. The LOD values were estimated to be 28, 40, and 58 μmol/L for K(+) , Na(+) , and Li(+) , respectively, what is comparable to that of conventional metal electrodes. When compared to the use metal electrodes, the proposed approach offers advantages regarding the easiness of fabrication, simplicity, and lower cost per device.

  10. Properties of linear arrays of Josephson junctions capacitively coupled to a diffusive metal

    NASA Astrophysics Data System (ADS)

    Lobos, Alejandro; Giamarchi, Thierry

    2011-03-01

    Josephson junctions arrays (JJAs) are strongly-correlated quantum systems showing a rich and complex behavior at low-temperatures. Besides their potential uses in applications, JJAs allow to investigate (under controlled conditions) many aspects of low-dimensional superconductivity which remain to be understood. In this work we study the phase diagram and the low-energy properties of a one-dimensional (1D) JJA capacitively coupled to a diffusive two-dimensional electron gas (2DEG) placed at a distance d , which provides dissipation. We derive an effective field-theoretical model for the 1D JJA coupled to the 2DEG, and predict a superconductor-insulator transition (SIT) at T = 0 , in agreement with former theoretical predictions. We discuss implications for transport experiments and for the observed SIT in 1DJJAs. Both in the superconducting and insulating phases, the coupling to the 2DEG produces deviations with respect to the resistivity as a function of T predicted for an isolated array. This work was supported in part by the Swiss SNF under MaNEP and division II.

  11. A novel in-line frequency sensor based on coupling capacitance for X-band application

    NASA Astrophysics Data System (ADS)

    Yan, Jiabin; Liao, Xiaoping; Yi, Zhenxiang

    2016-05-01

    This paper presents a novel in-line frequency sensor, based on coupling capacitance, for X-band applications. The novel frequency sensor can achieve absolute frequency measurement with a simple structure and no DC power consumption. Fabrication of the frequency sensor is completely compatible with the GaAs monolithic microwave integrated circuit process. A well-designed metal-insulator-metal capacitor is employed to couple a certain percentage of incident power and a thermoelectric power sensor is used to measure the coupled power. The sensor design is guided by HFSS simulation and a lumped circuit model. The results validate the effectiveness of the simulation and model, and show relatively good performance of the frequency sensor with simple and reliable components. The net sensitivity of the frequency sensor is about 1.43 mV (W•GHz)-1, and the measured S 11 and S 21 are better than  -14.8 dB and  -1.39 dB at X-band.

  12. Capacitively coupled radio-frequency hydrogen discharges: The role of kinetics

    NASA Astrophysics Data System (ADS)

    Marques, L.; Jolly, J.; Alves, L. L.

    2007-09-01

    This paper presents a systematic characterization of capacitively coupled radio-frequency hydrogen discharges, produced within a parallel plate cylindrical setup at different rf applied voltages (Vrf=50-600V), frequencies (f=13.56-40.68MHz), and pressures (p=0.2-1torr). A two-dimensional, time-dependent fluid model for charged particle transport is self-consistently solved coupled to a homogeneous kinetic model for hydrogen, including vibrationally excited molecular species and electronically excited atomic species. Numerical simulations are compared with experimental measurements of various plasma parameters. A good quantitative agreement is found between simulations and experiment for the coupled electrical power and the plasma potential. The model underestimates the values of the electron density, the self-bias potential, and the H(n =1) atom density with respect to measurements, but agrees with experiment when predicting that all these parameters increase with either Vrf, f, or p. The dissociation degree is about 10-3 for the work conditions considered. Simulations adopt a wall recombination probability for H atoms that was experimentally measured, thus accounting for surface modification with discharge operating conditions. Results show the key role played by the atomic wall recombination mechanism in plasma description.

  13. Capacitive micromachined ultrasonic transducers based on annular cell geometry for air-coupled applications.

    PubMed

    Na, Shuai; Chen, Albert I H; Wong, Lawrence L P; Li, Zhenhao; Macecek, Mirek; Yeow, John T W

    2016-09-01

    A novel design of an air-coupled capacitive micromachined ultrasonic transducer (CMUT) with annular cell geometry (annular CMUT) is proposed. Finite element analysis shows that an annular cell has a ratio of average-to-maximum displacement (RAMD) of 0.52-0.58 which is 58-76% higher than that of a conventional circular cell. The increased RAMD leads to a larger volume displacement which results in a 48.4% improved transmit sensitivity and 127.3% improved power intensity. Single-cell annular CMUTs were fabricated with 20-μm silicon plates on 13.7-μm deep and 1.35-mm wide annular cavities using the wafer bonding technique. The measured RAMD of the fabricated CMUTs is 0.54. The resonance frequency was measured to be 94.5kHz at 170-V DC bias. The transmit sensitivity was measured to be 33.83Pa/V and 25.85Pa/V when the CMUT was excited by a continuous wave and a 20-cycle burst, respectively. The receive sensitivity at 170-V DC bias was measured to be 7.7mV/Pa for a 20-cycle burst, and 15.0mV/Pa for a continuous incident wave. The proposed annular CMUT design demonstrates a significant improvement in transmit efficiency, which is an important parameter for air-coupled ultrasonic transducers. PMID:27352025

  14. Particle-in-cell/Monte Carlo simulation of capacitively coupled chlorine plasmas

    NASA Astrophysics Data System (ADS)

    Matsuoka, Kenji; Takao, Yoshinori; Eriguchi, Koji; Ono, Kouichi

    2011-10-01

    A better understanding of capacitively coupled plasmas (CCP) is still important, because of the development of dual-frequency CCP discharges, and also of the CCP mode that occurs in inductively coupled plasma discharges at low rf powers. This paper presents a two-dimensional particle-in-cell/Monte Carlo (PIC/MC) simulation of CCP chlorine discharges in an asymmetric parallel-plate rf plasma reactor. The model includes an external electrical circuit with a blocking capacitor and an rf power supply, which gives self-consistently the dc self-bias voltages on the powered electrode. Four charged species (e-, Cl2+, Cl+, Cl-) are taken into account in uniformly distributed Cl2 neutral backgrounds, together with electron-neutral elastic collision and ionization, dissociative attachment, positive ion-neutral elastic collision and charge transfer, and electron-ion and ion-ion recombination. The results indicated that the population of negative ions dominates that of electrons, which governs the plasma discharge and sheath dynamics, and thus the dynamics of incoming ion fluxes onto the powered electrode.

  15. Influence of frequency on the characteristics of VHF capacitively coupled plasmas in a 300 mm chamber

    NASA Astrophysics Data System (ADS)

    Hebner, G. A.; Barnat, E. V.; Miller, P. A.; Paterson, A.; Holland, J.; Lill, T.

    2004-09-01

    We have investigated the characteristics of VHF capacitively coupled plasmas produced in a modified Applied Materials chamber. The chamber had a 14-inch diameter upper electrode (source) that was driven at 10 to 160 MHz and a 300 mm diameter electrostatic chuck with a ceramic process kit that was driven at 13.56 MHz (bias). Diagnostics employed include a microwave interferometer to measure the line-integrated electron density, a hairpin microwave resonator to measure the spatially resolved electron density, absorption spectroscopy to determine the argon metastable temperature and density, laser induced fluorescence (LIF) to determine the spatial distribution of the excited species, and spatially resolved optical emission. We found that for constant source rf power, the electron density increased with rf frequency. The argon 1s5 metastable temperature was slightly above room temperature (300 - 400K), significantly cooler than our previous measurements in inductively coupled plasmas. The metastable density was not a strong function of source frequency or rf power. The metastable spatial distribution was always peaked in the center of the chamber and had a weak dependence on frequency. Scaling of the plasma parameters with frequency, power and pressure, and implications to energy deposition models will be discussed. This work was supported by Applied Materials and Sandia National Laboratories, a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  16. Fluid modelling of capacitively coupled radio-frequency discharges: a review

    NASA Astrophysics Data System (ADS)

    Alves, L. L.; Marques, L.

    2012-12-01

    This paper reviews the basis and the successes with the fluid modelling of capacitively coupled radio-frequency discharges, produced within a parallel-plate cylindrical setup at (single) 13.56-80 MHz frequencies, 6 × 10-2-6 Torr pressures and 50-1000 V rf-applied voltages, in SiH4-H2, H2 and N2. The two-dimensional, time-dependent model used in the simulations accounts for the production, transport and destruction of the charged particles (via the electron and ion continuity and momentum-transfer equations, and the electron mean energy transport equations), and of the excited species and/or radicals (via their rate balance equations, including very complete kinetic descriptions with several collisional-radiative production/destruction mechanisms, coupled to the two-term electron Boltzmann equation), accounting also for the self-consistent development of the rf field (via the solution to Poisson's equation). The charged particle transport equations are solved with and without corrective flux terms (due to inertia and friction effects), whose influence on results is discussed. In the case of silane-hydrogen mixtures, the model further includes a phenomenological description of the plasma-substrate interaction to calculate the deposition rate of a-Si : H thin films. In general, the model gives good predictions for the self-bias voltage, the coupled power and the intensities of radiative emission transitions (both average and spatially resolved), underestimating the electron density by a factor of 3-4.

  17. 3-Dimensional Modeling of Capacitively and Inductively Coupled Plasma Etching Systems

    NASA Astrophysics Data System (ADS)

    Rauf, Shahid

    2008-10-01

    Low temperature plasmas are widely used for thin film etching during micro and nano-electronic device fabrication. Fluid and hybrid plasma models were developed 15-20 years ago to understand the fundamentals of these plasmas and plasma etching. These models have significantly evolved since then, and are now a major tool used for new plasma hardware design and problem resolution. Plasma etching is a complex physical phenomenon, where inter-coupled plasma, electromagnetic, fluid dynamics, and thermal effects all have a major influence. The next frontier in the evolution of fluid-based plasma models is where these models are able to self-consistently treat the inter-coupling of plasma physics with fluid dynamics, electromagnetics, heat transfer and magnetostatics. We describe one such model in this paper and illustrate its use in solving engineering problems of interest for next generation plasma etcher design. Our 3-dimensional plasma model includes the full set of Maxwell equations, transport equations for all charged and neutral species in the plasma, the Navier-Stokes equation for fluid flow, and Kirchhoff's equations for the lumped external circuit. This model also includes Monte Carlo based kinetic models for secondary electrons and stochastic heating, and can take account of plasma chemistry. This modeling formalism allows us to self-consistently treat the dynamics in commercial inductively and capacitively coupled plasma etching reactors with realistic plasma chemistries, magnetic fields, and reactor geometries. We are also able to investigate the influence of the distributed electromagnetic circuit at very high frequencies (VHF) on the plasma dynamics. The model is used to assess the impact of azimuthal asymmetries in plasma reactor design (e.g., off-center pump, 3D magnetic field, slit valve, flow restrictor) on plasma characteristics at frequencies from 2 -- 180 MHz. With Jason Kenney, Ankur Agarwal, Ajit Balakrishna, Kallol Bera, and Ken Collins.

  18. Analysis of ecstasy tablets using capillary electrophoresis with capacitively coupled contactless conductivity detection.

    PubMed

    Porto, Suely K S S; Nogueira, Thiago; Blanes, Lucas; Doble, Philip; Sabino, Bruno D; do Lago, Claudimir L; Angnes, Lúcio

    2014-11-01

    A method for the identification of 3,4-methylenedioxymethamphetamine (MDMA) and meta-chlorophenylpiperazine (mCPP) was developed employing capillary electrophoresis (CE) with capacitively coupled contactless conductivity detection (C(4) D). Sample extraction, separation, and detection of "Ecstasy" tablets were performed in <10 min without sample derivatization. The separation electrolyte was 20 mm TAPS/Lithium, pH 8.7. Average minimal detectable amounts for MDMA and mCPP were 0.04 mg/tablet, several orders of magnitude lower than the minimum amount encountered in a tablet. Seven different Ecstasy tablets seized in Rio de Janeiro, Brazil, were analyzed by CE-C(4) D and compared against routine gas chromatography-mass spectrometry (GC-MS). The CE method demonstrated sufficient selectivity to discriminate the two target drugs, MDMA and mCPP, from the other drugs present in seizures, namely amphepramone, fenproporex, caffeine, lidocaine, and cocaine. Separation was performed in <90 sec. The advantages of using C(4) D instead of traditional CE-UV methods for in-field analysis are also discussed.

  19. Influence of nanoparticle formation on discharge properties in argon-acetylene capacitively coupled radio frequency plasmas

    NASA Astrophysics Data System (ADS)

    Wegner, Th.; Hinz, A. M.; Faupel, F.; Strunskus, T.; Kersten, H.; Meichsner, J.

    2016-02-01

    This contribution presents experimental results regarding the influence of nanoparticle formation in capacitively coupled radio frequency (13.56 MHz) argon-acetylene plasmas. The discharge is studied using non-invasive 160 GHz Gaussian beam microwave interferometry and optical emission spectroscopy. Particularly, the temporal behavior of the electron density from microwave interferometry is analyzed and compared with the changing plasma emission and self-bias voltage caused by nanoparticle formation. The periodic particle formation with a cycle duration between 30 s and 140 s starts with an electron density drop over more than one order of magnitude below the detection limit (8 × 1014 m-3). The electron density reduction is the result of electron attachment processes due to negative ions and nanoparticle formation. The onset time constant of nanoparticle formation is five times faster compared to the expulsion of the particles from the plasma due to multi-disperse size distribution. Moreover, the intensity of the argon transition lines increases and implies a rising effective electron temperature. The cycle duration of the particle formation is affected by the total gas flow rate and exhibits an inverse proportionality to the square of the total gas flow rate. The variation in the total gas flow rate influences the force balance, which determines the confinement time of the nanoparticles. As a further result, the cycle duration is dependent on the axial position of the powered electrode, which also corresponds to different distances relative to the fixed optical axis of the microwave interferometer.

  20. Heart Rate Variability Monitoring during Sleep Based on Capacitively Coupled Textile Electrodes on a Bed

    PubMed Central

    Lee, Hong Ji; Hwang, Su Hwan; Yoon, Hee Nam; Lee, Won Kyu; Park, Kwang Suk

    2015-01-01

    In this study, we developed and tested a capacitively coupled electrocardiogram (ECG) measurement system using conductive textiles on a bed, for long-term healthcare monitoring. The system, which was designed to measure ECG in a bed with no constraints of sleep position and posture, included a foam layer to increase the contact region with the curvature of the body and a cover to ensure durability and easy installation. Nine healthy subjects participated in the experiment during polysomnography (PSG), and the heart rate (HR) coverage and heart rate variability (HRV) parameters were analyzed to evaluate the system. The experimental results showed that the mean of R-peak coverage was 98.0% (95.5%–99.7%), and the normalized errors of HRV time and spectral measures between the Ag/AgCl system and our system ranged from 0.15% to 4.20%. The root mean square errors for inter-beat (RR) intervals and HR were 1.36 ms and 0.09 bpm, respectively. We also showed the potential of our developed system for rapid eye movement (REM) sleep and wake detection as well as for recording of abnormal states. PMID:26007716

  1. Experimental investigations of driving frequency effect in low-pressure capacitively coupled oxygen discharges

    SciTech Connect

    Liu, Jia; Liu, Yong-Xin; Liu, Gang-Hu; Gao, Fei; Wang, You-Nian

    2015-04-14

    The effect of driving frequency on the electron density is investigated in low-pressure capacitively coupled oxygen plasmas by utilizing a floating hairpin probe. The power absorbed by the plasma is investigated and it is found that the power lost in the matching network can reach 50% or higher under certain conditions. The effect of driving frequency on the electron density is studied from two aspects, i.e., constant absorbed power and electrode voltage. In the former case, the electron density increases with the driving frequency increasing from 13.56 to 40.68 MHz and slightly changes depending on the gas pressures with the frequency further increasing to 100 MHz. In the latter case, the electron density rapidly increases when the driving frequency increases from 13.56 to 40.68 MHz, and then decreases with the frequency further increasing to 100 MHz. The electron series resonance is observed at 40.68 MHz and can be attributed to the higher electron density. And the standing wave effect also plays an important role in increasing electron density at 100 MHz and 2.6 Pa.

  2. Experimental and numerical investigations of the phase-shift effect in capacitively coupled discharges

    SciTech Connect

    Gao, Fei; Zhang, Yu-Ru; Zhao, Shu-Xia; Wang, You-Nian

    2014-08-15

    The phase-shift effect has been investigated by a Langmuir probe and a fluid model in Ar capacitively coupled plasmas at 50 mTorr. In the discharge, two sources with the same frequency, i.e., 27.12 MHz, are applied on the top and bottom electrodes simultaneously, and the phase shift between them varies from 0 to π. It is found that the electron density has an off-axis peak near the radial edge when the phase difference is equal to 0 due to the electrostatic edge effect, and the best radial uniformity is observed at a phase difference equal to π. Furthermore, when the voltage increases, the best radial uniformity is obtained at lower phase shift values. Moreover, the electron energy probability function has a bi-temperature structure at all the selected phase differences at r = 1–15 cm. The evolution of the plasma characteristics with the phase difference implies that the best radial uniformity can be obtained, by balancing the electrostatic edge effect and the phase shift effect.

  3. Reversal of the asymmetry in a cylindrical coaxial capacitively coupled Ar/Cl2 plasma

    DOE PAGESBeta

    Upadhyay, Janardan; Im, Do; Popović, Svetozar; Vušković, Leposava; Valente-Feliciano, Anne -Marie; Phillips, Larry

    2015-10-08

    The reduction of the asymmetry in the plasma sheath voltages of a cylindrical coaxial capacitively coupled plasma is crucial for efficient surface modification of the inner surfaces of concave three-dimensional structures, including superconducting radio frequency cavities. One critical asymmetry effect is the negative dc self-bias, formed across the inner electrode plasma sheath due to its lower surface area compared to the outer electrode. The effect on the self-bias potential with the surface enhancement by geometric modification on the inner electrode structure is studied. The shapes of the inner electrodes are chosen as cylindrical tube, large and small pitch bellows, andmore » disc-loaded corrugated structure (DLCS). The dc self-bias measurements for all these shapes were taken at different process parameters in Ar/Cl2 discharge. Lastly, the reversal of the negative dc self-bias potential to become positive for a DLCS inner electrode was observed and the best etch rate is achieved due to the reduction in plasma asymmetry.« less

  4. Heart Rate Variability Monitoring during Sleep Based on Capacitively Coupled Textile Electrodes on a Bed.

    PubMed

    Lee, Hong Ji; Hwang, Su Hwan; Yoon, Hee Nam; Lee, Won Kyu; Park, Kwang Suk

    2015-05-14

    In this study, we developed and tested a capacitively coupled electrocardiogram (ECG) measurement system using conductive textiles on a bed, for long-term healthcare monitoring. The system, which was designed to measure ECG in a bed with no constraints of sleep position and posture, included a foam layer to increase the contact region with the curvature of the body and a cover to ensure durability and easy installation. Nine healthy subjects participated in the experiment during polysomnography (PSG), and the heart rate (HR) coverage and heart rate variability (HRV) parameters were analyzed to evaluate the system. The experimental results showed that the mean of R-peak coverage was 98.0% (95.5%-99.7%), and the normalized errors of HRV time and spectral measures between the Ag/AgCl system and our system ranged from 0.15% to 4.20%. The root mean square errors for inter-beat (RR) intervals and HR were 1.36 ms and 0.09 bpm, respectively. We also showed the potential of our developed system for rapid eye movement (REM) sleep and wake detection as well as for recording of abnormal states.

  5. Numerical simulations of electrical asymmetry effect on electronegative plasmas in capacitively coupled rf discharge

    SciTech Connect

    Zhang Quanzhi; Jiang Wei; Wang Younian; Hou Lujing

    2011-01-01

    Recently a so-called electrical asymmetry effect (EAE), which could achieve high-degree separate control of ion flux and energy in dual-frequency capacitively coupled radio-frequency (CCRF) discharges, was discovered theoretically by Heil et al. [J. Phys. D: Appl. Phys. 41, 165202 (2008)] and was confirmed by experiments and theory/numerical simulations later on for electropositive argon discharges. In this work simulations based on particle-in-cell/Monte Carlo collision are performed to study the EAE on electronegative oxygen plasmas in geometrically symmetric CCRF discharges. Dual frequency discharges operating at 13.56 and 27.12 MHz are simulated for different pressures and the results are compared with those of electropositive argon discharges at the same conditions. It is found that in general the EAE on oxygen discharges has similar behavior as on argon discharge: The self-bias voltage {eta} increases monotonically and almost linearly with the increase in the phase angle {theta} between the two driving voltages in the range 0<{theta}<90 deg. , and the maximum ion energy varies by a factor of 3 by adjusting {theta}. However, the ion flux varies with {theta} by {+-}12% for low pressure and by {+-}15% for higher pressure, due primarily to an enhanced plasma series resonance, which then leads to dramatic changes in plasma density, power absorption and consequently the electronegativity. This may place a limitation for achieving separate control of ion energy and flux for electronegative plasma via the EAE.

  6. Experimental and simulation study of a capacitively coupled oxygen discharge driven by tailored voltage waveforms

    NASA Astrophysics Data System (ADS)

    Derzsi, Aranka; Lafleur, Trevor; Booth, Jean-Paul; Korolov, Ihor; Donkó, Zoltán

    2016-02-01

    We report experimental and particle-based kinetic simulation studies of low-pressure capacitively coupled oxygen plasmas driven by tailored voltage waveforms that consist of up to four harmonics of base frequency 13.56 MHz. Experimentally determined values of DC self-bias and electrical power deposition, as well as flux density and flux-energy distribution of the positive ions at the grounded electrode are compared with simulation data for a wide range of operating conditions. Very good agreement is found for self-bias and flux-energy distribution of the positive ions at the electrodes, while a fair agreement is reached for discharge power and ion flux data. The simulated spatial and temporal behaviour of the electric field, electron density, electron power absorption, ionization rate and mean electron energy shows a transition between sheath expansion heating and drift-ambipolar discharge modes, induced by changing either the number of harmonics comprising the excitation waveform or the gas pressure. The simulations indicate that under our experimental conditions the plasma operates at high electronegativity, and also reveal the crucial role of {{\\text{O}}2}≤ft({{a}1}{{Δ }g}\\right) singlet metastable molecules in establishing discharge behavior via the fast destruction of negative ions within the bulk plasma.

  7. Spectroscopy diagnostic of dual-frequency capacitively coupled CHF{sub 3}/Ar plasma

    SciTech Connect

    Liu, Wen-Yao; Du, Yong-Quan; Liu, Yong-Xin; Liu, Jia; Zhao, Tian-Liang; Wang, You-Nian; Xu, Yong; Li, Xiao-Song; Zhu, Ai-Min

    2013-11-15

    A combined spectroscopic method of absorption, actinometry, and relative optical emission intensity is employed to determine the absolute CF{sub 2} density, the relative F and H densities, H atom excitation temperature and the electron density in dual-frequency (60/2 MHz) capacitively coupled CHF{sub 3}/Ar plasmas. The effects of different control parameters, such as high-frequency (HF) power, low-frequency (LF) power, gas pressure, gap length and content of CHF{sub 3}, on the concentration of radical CF{sub 2}, F, and H and excitation temperature are discussed, respectively. It is found that the concentration of CF{sub 2} is strongly dependent on the HF power, operating pressure and the proportion of CHF{sub 3} in feed gas, while it is almost independent of the LF power and the gap length. A higher concentration ratio of F to CF{sub 2} could be obtained in dual-frequency discharge case. Finally, the generation and decay mechanisms of CF{sub 2} and F were also discussed.

  8. Capacitively Coupled RF Plasmas for the Synthesis of Silicon Nanocrystals: Scaling and Mechanisms

    NASA Astrophysics Data System (ADS)

    Markosyan, Aram H.; Le Picard, Romain; Porter, David H.; Girshick, Steven L.; Kushner, Mark J.

    2015-09-01

    Silicon nanocrystals (SNCs) are of interest for light emitting electronics, photovoltaics, and biotechnology. SNCs are produced in low pressure capacitively coupled plasmas (CCPs) sustained in SiH4 containing mixtures. To optimize these applications, it is necessary to control the size distribution of the SNCs. Particles 3-5 nm diameter are typically tailored by flow rates and power, however the fundamental processes responsible for this size control are not well understood. We developed a 2-d computer model for RF powered CCPs to predict the synthesis of SNCs. An aerosol sectional model was incorporated into the Hybrid Plasma Equipment Model. The reactor is a quartz tube a few mm in diameter through which 100 sccm Ar and 15 sccm He/SiH4 = 95/5 at 2 Torr are flowed. The SNC residence time is 1-2 ms in the dense plasma region near the electrodes. We found that the distribution of plasma potential is important in determining the growth and size distribution of the SNCs. The SNCs having long residence times in the plasma, thereby enabling growth, are usually negatively charged. To ultimately allow these SNCs to flow out of the plasma, the distribution of the plasma potential must enable the particles to be entrained in the neutral gas flow without a significant potential barrier. We also found that agglomeration of particles of <1 nm is important in the rate of growth of SNCs. Work supported by DOE (DE-SC0001939) and NSF (CHE-124752).

  9. Capacitively coupled hydrogen plasmas sustained by tailored voltage waveforms: excitation dynamics and ion flux asymmetry

    NASA Astrophysics Data System (ADS)

    Bruneau, B.; Diomede, P.; Economou, D. J.; Longo, S.; Gans, T.; O'Connell, D.; Greb, A.; Johnson, E.; Booth, J.-P.

    2016-08-01

    Parallel plate capacitively coupled plasmas in hydrogen at relatively high pressure (~1 Torr) are excited with tailored voltage waveforms containing up to five frequencies. Predictions of a hybrid model combining a particle-in-cell simulation with Monte Carlo collisions and a fluid model are compared to phase resolved optical emission spectroscopy measurements, yielding information on the dynamics of the excitation rate in these discharges. When the discharge is excited with amplitude asymmetric waveforms, the discharge becomes electrically asymmetric, with different ion energies at each of the two electrodes. Unexpectedly, large differences in the \\text{H}2+ fluxes to each of the two electrodes are caused by the different \\text{H}3+ energies. When the discharge is excited with slope asymmetric waveforms, only weak electrical asymmetry of the discharge is observed. In this case, electron power absorption due to fast sheath expansion at one electrode is balanced by electron power absorption at the opposite electrode due to a strong electric field reversal.

  10. Slope and amplitude asymmetry effects on low frequency capacitively coupled carbon tetrafluoride plasmas

    NASA Astrophysics Data System (ADS)

    Bruneau, B.; Korolov, I.; Lafleur, T.; Gans, T.; O'Connell, D.; Greb, A.; Derzsi, A.; Donkó, Z.; Brandt, S.; Schüngel, E.; Schulze, J.; Johnson, E.; Booth, J.-P.

    2016-04-01

    We report investigations of capacitively coupled carbon tetrafluoride (CF4) plasmas excited with tailored voltage waveforms containing up to five harmonics of a base frequency of 5.5 MHz. The impact of both the slope asymmetry, and the amplitude asymmetry, of these waveforms on the discharge is examined by combining experiments with particle-in-cell simulations. For all conditions studied herein, the discharge is shown to operate in the drift-ambipolar mode, where a comparatively large electric field in the plasma bulk (outside the sheaths) is the main mechanism for electron power absorption leading to ionization. We show that both types of waveform asymmetries strongly influence the ion energy at the electrodes, with the particularity of having the highest ion flux on the electrode where the lowest ion energy is observed. Even at the comparatively high pressure (600 mTorr) and low fundamental frequency of 5.5 MHz used here, tailoring the voltage waveforms is shown to efficiently create an asymmetry of both the ion energy and the ion flux in geometrically symmetric reactors.

  11. Experimental investigations of driving frequency effect in low-pressure capacitively coupled oxygen discharges

    NASA Astrophysics Data System (ADS)

    Liu, Jia; Liu, Yong-Xin; Liu, Gang-Hu; Gao, Fei; Wang, You-Nian

    2015-04-01

    The effect of driving frequency on the electron density is investigated in low-pressure capacitively coupled oxygen plasmas by utilizing a floating hairpin probe. The power absorbed by the plasma is investigated and it is found that the power lost in the matching network can reach 50% or higher under certain conditions. The effect of driving frequency on the electron density is studied from two aspects, i.e., constant absorbed power and electrode voltage. In the former case, the electron density increases with the driving frequency increasing from 13.56 to 40.68 MHz and slightly changes depending on the gas pressures with the frequency further increasing to 100 MHz. In the latter case, the electron density rapidly increases when the driving frequency increases from 13.56 to 40.68 MHz, and then decreases with the frequency further increasing to 100 MHz. The electron series resonance is observed at 40.68 MHz and can be attributed to the higher electron density. And the standing wave effect also plays an important role in increasing electron density at 100 MHz and 2.6 Pa.

  12. PIC/MCC simulation of capacitively coupled discharges: Effect of particle management and integration

    NASA Astrophysics Data System (ADS)

    Sun, Anbang; Becker, Markus M.; Loffhagen, Detlef

    2016-09-01

    A PIC/MCC simulation model for the analysis of low-temperature discharge plasmas is represented which takes the common leapfrog and the velocity Verlet algorithm for the particle integration, adaptive particle management as well as parallel computing using MPI into account. Main features of the model including the impact of super particle numbers, adaptive particle management and the time step size for the different integration methods are represented. The investigations are performed for low-pressure capacitively coupled radio frequency discharges in helium and argon. Besides a code verification by comparison with benchmark simulation results in helium it is shown that an adaptive particle management is particularly suitable for the simulation of discharges at elevated pressures where boundary effects and processes in the sheath regions are important. Furthermore, it is pointed out that the velocity Verlet integration scheme allows to speed up the PIC/MCC simulations compared to the leapfrog method because it makes the use of larger time steps at the same accuracy possible.

  13. Analysis of ecstasy tablets using capillary electrophoresis with capacitively coupled contactless conductivity detection.

    PubMed

    Porto, Suely K S S; Nogueira, Thiago; Blanes, Lucas; Doble, Philip; Sabino, Bruno D; do Lago, Claudimir L; Angnes, Lúcio

    2014-11-01

    A method for the identification of 3,4-methylenedioxymethamphetamine (MDMA) and meta-chlorophenylpiperazine (mCPP) was developed employing capillary electrophoresis (CE) with capacitively coupled contactless conductivity detection (C(4) D). Sample extraction, separation, and detection of "Ecstasy" tablets were performed in <10 min without sample derivatization. The separation electrolyte was 20 mm TAPS/Lithium, pH 8.7. Average minimal detectable amounts for MDMA and mCPP were 0.04 mg/tablet, several orders of magnitude lower than the minimum amount encountered in a tablet. Seven different Ecstasy tablets seized in Rio de Janeiro, Brazil, were analyzed by CE-C(4) D and compared against routine gas chromatography-mass spectrometry (GC-MS). The CE method demonstrated sufficient selectivity to discriminate the two target drugs, MDMA and mCPP, from the other drugs present in seizures, namely amphepramone, fenproporex, caffeine, lidocaine, and cocaine. Separation was performed in <90 sec. The advantages of using C(4) D instead of traditional CE-UV methods for in-field analysis are also discussed. PMID:25039689

  14. Effects of interelectrode gap on high frequency and very high frequency capacitively coupled plasmas

    SciTech Connect

    Bera, Kallol; Rauf, Shahid; Ramaswamy, Kartik; Collins, Ken

    2009-07-15

    Capacitively coupled plasma (CCP) discharges using high frequency (HF) and very high frequency (VHF) sources are widely used for dielectric etching in the semiconductor industry. A two-dimensional fluid plasma model is used to investigate the effects of interelectrode gap on plasma spatial characteristics of both HF and VHF CCPs. The plasma model includes the full set of Maxwell's equations in their potential formulation. The peak in plasma density is close to the electrode edge at 13.5 MHz for a small interelectrode gap. This is due to electric field enhancement at the electrode edge. As the gap is increased, the plasma produced at the electrode edge diffuses to the chamber center and the plasma becomes more uniform. At 180 MHz, where electromagnetic standing wave effects are strong, the plasma density peaks at the chamber center at large interelectrode gap. As the interelectrode gap is decreased, the electron density increases near the electrode edge due to inductive heating and electrostatic electron heating, which makes the plasma more uniform in the interelectrode region.

  15. Characteristics of VHF capacitively coupled plasmas in a 300 mm chamber

    NASA Astrophysics Data System (ADS)

    Hebner, G. A.; Miller, P. A.; Barnat, E. V.; Paterson, A.; Holland, J.; Lill, T.

    2004-09-01

    We have investigated the characteristics of VHF capacitively coupled plasmas produced in a modified Applied Materials chamber. The chamber had a 14-inch diameter upper electrode (source) that was driven at 10 to 160 MHz and a 300 mm diameter electrostatic chuck with a ceramic process kit that was driven at 13.56 MHz (bias). Diagnostics employed include rf diagnostics to measure the voltage and current, Bdot probes to measure the spatial magnetic fields, a microwave interferometer to measure the line-integrated electron density, a hairpin microwave resonator to measure the spatially resolved electron density, absorption spectroscopy to determine the argon metastable temperature and density, laser induced fluorescence (LIF) to determine the spatial distribution of the excited species, and spatially resolved optical emission. Scaling of the plasma parameters with frequency, power and pressure, and implications to energy deposition models will be discussed. This work was supported by Applied Materials and Sandia National Laboratories, a multiprogram laboratory operated by Sandia Corporation, a Lockheed Martin Company for the United States Department of Energy's National Nuclear Security Administration under contract DE-AC04-94AL85000.

  16. Experimental study of spatial nonuniformities in 100 MHz capacitively coupled plasma using optical probe

    SciTech Connect

    Volynets, V. N.; Ushakov, A. G.; Sung, D.; Tolmachev, Y. N.; Pashkovsky, V. G.; Lee, J. B.; Kwon, T. Y.; Jeong, K. S.

    2008-05-15

    Plasma spatial nonuniformities in the 100 MHz rf driven capacitively coupled reactor used for reactive ion etching of 300 mm substrates were experimentally studied using a linear scanning optical emission spectroscopy probe. Radial profiles of plasma emission intensity were measured both in argon and fluorocarbon-containing gas mixtures in the pressure interval of 10-80 mTorr and the rf power range of 500-1250 W. It was demonstrated that the plasma emission profiles strongly depend on the working gas composition and pressure. The profiles have a bell-like shape at pressures about 10 mTorr for all gases. As the pressure increases, the profile shape becomes more complex with the central and peripheral peaks, and the amplitudes of the peaks strongly depend on the working gas composition. It is suggested that the emission profiles show plasma spatial nonuniformities that can influence the etching rate profiles obtained with such systems. According to the existing theoretical models, the most probable reasons for these plasma nonuniformities are charged particle radial diffusion at low pressures (about 10 mTorr), as well as the standing wave and skin and edge effects at higher pressures. Using the experimental emission profiles, the working conditions have been found that allow one to achieve the most uniform plasma for discharges in argon and fluorocarbon-containing gas mixtures.

  17. Study of fluorocarbon plasma in 60 and 100 MHz capacitively coupled discharges using mass spectrometry

    SciTech Connect

    Ushakov, Andrey; Volynets, Vladimir; Jeong, Sangmin; Sung, Dougyong; Ihm, Yongho; Woo, Jehun; Han, Moonhyeong

    2008-09-15

    The signals of positive ions and radicals formed in the fluorocarbon plasma of the capacitively coupled plasma reactor were measured using a quadrupole mass spectrometry and optical emission actinometry. The plasma was produced at 60 and 100 MHz frequencies for the same reactor configuration and gas mixtures. Experiments were performed at 25 mTorr with a SiO{sub 2} wafer on the grounded electrode. Mass spectra of ions were measured in C{sub 4}F{sub 8}/O{sub 2}/Ar and C{sub 4}F{sub 6}/O{sub 2}/Ar gas mixtures at 500-1500 W generator powers. For 60 and 100 MHz discharges production of fluorocarbon ions and radicals is discussed. It was found that the production of heavy species increases with frequency. The high mass signals such as C{sub 3}F{sub 3}{sup +}, C{sub 2}F{sub 4}{sup +}, C{sub 2}F{sub 5}{sup +}, C{sub 3}F{sub 5}{sup +}, C{sub 4}F{sub 7}{sup +} decrease when CHF{sub 3} is added to the gas mixture. However, the signals of CF{sub x}{sup +} (x=1,2,3) do not change significantly. These results are compared to the results of polymer film deposition on the wafer. It was suggested to control the polymerization film formation by adding small amount of CHF{sub 3} to the process mixture.

  18. Studies on the effect of finite geometrical asymmetry in dual capacitively coupled radio frequency plasma

    NASA Astrophysics Data System (ADS)

    Bora, B.

    2015-10-01

    In recent years, dual capacitively coupled radio frequency (CCRF) glow discharge plasma has been widely studied in the laboratory because of its simpler design and high efficiency for different material processing applications such as thin-film deposition, plasma etching, sputtering of insulating materials etc. The main objective of studies on dual frequency CCRF plasma has been the independent control of ion energy and ion flux using an electrical asymmetry effect (EAE). Most studies have been reported in electrode configurations that are either geometrically symmetric (both electrodes are equal) or completely asymmetric (one electrode is infinitely bigger than the other). However, it seems that most of the laboratory CCRF plasmas have finite electrode geometry. In addition, plasma series resonance (PSR) and electron bounce resonance (EBR) heating also come into play as a result of geometrical asymmetry as well as EAE. In this study, a dual frequency CCRF plasma has been studied in which the dual frequency CCRF has been coupled to the lumped circuit model of the plasma and the time-independent fluid model of the plasma sheath, in order to study the effect of finite geometrical asymmetry on the generation of dc-self bias and plasma heating. The dc self-bias is found to strongly depend on the ratio of the area between the electrodes. The dc self-bias is found to depend on the phase angle between the two applied voltage waveforms. The EAE and geometrical asymmetry are found to work differently in controlling the dc self-bias. It can be concluded that the phase angle between the two voltage waveforms in dual CCRF plasmas has an important role in determining the dc self-bias and may be used for controlling the plasma properties in the dual frequency CCRF plasma.

  19. Optical vibration measurements of cross coupling effects in capacitive micromachined ultrasonic transducer arrays

    NASA Astrophysics Data System (ADS)

    Leirset, Erlend; Aksnes, Astrid

    2011-05-01

    Optical vibration measurement systems are excellent tools for characterizing ultrasonic transducers. This paper presents measurements on immersed arrays of capacitive ultrasonic transducers (CMUTs) using a heterodyne interferometer. The interferometer allows measurements of vibrations from DC up to 1 GHz with a noise floor of ~1pm/√Hz. Previously CMUTs have been characterized in air. The transducer is intended for intravascular use. Therefore the CMUTs were characterized in the transparent fluids kerosene and rapeseed oil that have acoustic properties closer to blood. The optical measurements on immersed CMUTs were validated by assessing the measurement errors caused by the acousto optic effects in the fluid. When immersed there is significant cross coupling between individual CMUTs within an array. Simulations presented here indicate that this causes an acoustic wave mode that is bound to the interface between the CMUTs and the fluid. This is confirmed by measurements of the phase velocity and attenuation coefficient of this wave. The measurement results indicate that the wave exists up to a maximum frequency and that the attenuation constant increases with increasing frequency. Rapeseed oil causes a significantly larger attenuation coefficient than kerosene, which most probably is due to a considerable difference in fluid viscosities. There was a mismatch between the simulated and measured phase velocity for low frequencies. It is likely that the cause of this is coupling between the fluid CMUT interface waves and Lamb waves in the substrate of the CMUT array. Measurements performed with the heterodyne interferometer have confirmed the presence of dispersive waves bound to the surface of the transducer by directly showing their propagation along the array. The setup has also characterized the bound waves by measuring dispersion relations.

  20. PIC-MCC/Fluid Hybrid Model for Low Pressure Capacitively Coupled O{sub 2} Plasma

    SciTech Connect

    Bera, Kallol; Rauf, Shahid; Collins, Ken

    2011-05-20

    Low pressure capacitively coupled plasmas are extensively used for advanced microelectronic device fabrication. Due to long electron mean free path and large bias voltages in this regime, kinetic effects play an important role in the dynamics of low pressure discharges. To take account of the kinetic effects, a one-dimensional hybrid plasma model has been developed that couples the Particle-In-Cell (PIC) technique for charged species and a fluid method for neutral species. The PIC model uses the Monte Carlo Collision (MCC) method to account for collision processes. The fluid model for neutral species takes into account species transport in the plasma, chemical reactions, and surface processes. An electronegative O{sub 2} plasma is simulated for a range of pressures (10-300 mTorr) and rf voltages (200-600 V) at 60 MHz. Our model for the O{sub 2} plasma considers electrons, O{sub 2}{sup +}, O{sup -}, O, and O*. The reaction mechanism includes electron impact dissociation, ionization, dissociative attachment and ion-ion recombination. Computational results are compared to our previous simulations for an electropositive Ar discharge. The electrons primarily absorb power from the external power supply at the sheath edge during sheath expansion. Energetic beam electrons are generated at the sheath edge during electron heating, which are responsible for plasma production and sustenance through collisions. The negative ions are found to be confined in the bulk plasma due to the potential well. The ratio of negative ions to electrons increases with increase in pressure and decrease in rf voltage. The spatial profiles of charged and neutral species in the plasma are found to primarily depend on species sources due to collisional processes.

  1. Geophysical characterization of the Lollie Levee near Conway, Arkansas, using capacitively coupled resistivity, coring, and direct push logging

    USGS Publications Warehouse

    Gillip, Jonathan A.; Payne, Jason D.

    2011-01-01

    A geophysical characterization of Lollie Levee near Conway, Arkansas, was conducted in February 2011. A capacitively coupled resistivity survey (using Geometric's OhmMapper) was completed along the top and toe of the 6.7-mile levee. Two-dimensional inversions were conducted on the geophysical data. As a quality-control measure, cores and direct push logs were taken at approximately 1-mile intervals along the levee. The capacitively coupled resistivity survey, the coring, and the direct push logs were used to characterize the geologic materials. Comparison of the cores and the direct push log data, along with published resistivity values, indicates that resistivity values of 200 Ohm-meters or greater represent relatively clean sand, with decreasing resistivity values occurring with increasing silt and clay content. The cores indicated that the levee is composed of a heterogeneous mixture of sand, silt, and clay. The capacitively coupled resistivity sections confirm that the levee is composed of a heterogeneous mixture of high and low resistivity materials and show that the composition of the levee varies spatially. The geologic materials underlying the levee vary spatially as a result of the geologic processes that deposited them. In general, the naturally deposited geologic materials underlying the levee contain a greater amount of low resistivity materials in the southern extent of the levee.

  2. Formation Kinetics and Control of Dust Particles in Capacitively-Coupled Reactive Plasmas

    NASA Astrophysics Data System (ADS)

    Watanabe, Yukio; Shiratani, Masaharu; Koga, Kazunori

    Formation kinetics and behavior of dust particles below about 10 nm in size, referred to as clusters, in silane capacitively-coupled RF plasmas are studied using double pulse discharge and photon-counting laser-light-scattering methods. Even under so-called device quality conditions, clusters of ˜1011 cm-3 high compared to a plasma ion density of ˜10-9 cm3 are found at t ˜ 50 ms after the discharge initiation. Clusters begin to be composed of two size groups at t ˜ 10 ms. The ones in the small size group have an almost constant average size of ˜0.5 nm during the discharge period, while the ones in the large size group grow at a rate of ˜4 nm/s. This result indicates that the large clusters are nucleated by the small ones containing 3-4 Si atoms. Various methods for suppressing cluster growth have also been studied using two in situ cluster detection methods. Since species contributing to the initial growth of clusters are principally produced in the radical production region around the plasma/sheath boundary near the rf electrode, the pulse discharge modulation which has the discharge-off period in one modulation cycle longer than the diffusion time of clusters through the radical production region is effective in reducing the growth of clusters. Thermophoretic force due to heating of the grounded electrode drives neutral clusters above a few nm in size toward the cool RF electrode which is at room temperature. Periodical pulse discharge modulation is much more effective in reducing the cluster density when it is combined with grounded electrode heating. Hydrogen dilution of a high H2/SiH4 concentration ratio above about 5 is useful for suppressing cluster growth especially in the radical production region near the RF electrode.

  3. A parallel-architecture parametric equalizer for air-coupled capacitive ultrasonic transducers.

    PubMed

    McSweeney, Sean G; Wright, William M D

    2012-01-01

    Parametric equalization is rarely applied to ultrasonic transducer systems, for which it could be used on either the transmitter or the receiver to achieve a desired response. An optimized equalizer with both bump and cut capabilities would be advantageous for ultrasonic systems in applications in which variations in the transducer performance or the properties of the propagating medium produce a less-than-desirable signal. Compensation for non-ideal transducer response could be achieved using equalization on a device-by-device basis. Additionally, calibration of ultrasonic systems in the field could be obtained by offline optimization of equalization coefficients. In this work, a parametric equalizer for ultrasonic applications has been developed using multiple bi-quadratic filter elements arranged in a novel parallel arrangement to increase the flexibility of the equalization. The equalizer was implemented on a programmable system-on-chip (PSOC) using a small number of parallel 4th-order infinite impulse response switchedcapacitor band-pass filters. Because of the interdependency of the required coefficients for the switched capacitors, particle swarm optimization (PSO) was used to determine the optimum values. The response of a through-transmission system using air-coupled capacitive ultrasonic transducers was then equalized to idealized Hamming function or brick-wall frequencydomain responses. In each case, there was excellent agreement between the equalized signals and the theoretical model, and the fidelity of the time-domain response was maintained. The bandwidth and center frequency response of the system were significantly improved. It was also shown that the equalizer could be used on either the transmitter or the receiver, and the system could compensate for the effects of transmitterreceiver misalignment.

  4. Electromembrane extraction of heavy metal cations followed by capillary electrophoresis with capacitively coupled contactless conductivity detection.

    PubMed

    Kubáň, Pavel; Strieglerová, Lenka; Gebauer, Petr; Boček, Petr

    2011-04-01

    Electromembrane extraction (EME) was used as an off-line sample pre-treatment method for the determination of heavy metal cations in aqueous samples using CE with capacitively coupled contactless conductivity detection (CE-C(4) D). A short segment of porous polypropylene hollow fibre was penetrated with 1-octanol and 0.5% v/v bis(2-ethylhexyl)phosphonic acid and constituted a low cost, single use, disposable supported liquid membrane, which selectively transported and pre-concentrated heavy metal cations into the fibre lumen filled with 100 mM acetic acid acceptor solution. Donor solutions were standard solutions and real samples dissolved in deionized water at neutral pH. At optimized EME conditions (penetration time, 5 s; applied voltage, 75 V; and stirring rate, 750 rpm), 15-42% recoveries of heavy metal cations were achieved for a 5 min extraction time. Repeatability of the EME pre-treatment was examined for six independent EME runs and ranged from 6.6 to 11.1%. Limits of detection for the EME-CE-C(4) D method ranged from 25 to 200 nM, resulting into one to two orders of magnitude improvement compared with CE-C(4) D without sample treatment. The developed EME sample pre-treatment procedure was applied to the analysis of heavy metal cations in tap water and powdered milk samples. Zinc in the real samples was identified and quantified in a background electrolyte solution consisting of 20 mM L-histidine and 30 mM acetic acid at pH 4.95 in about 3 min.

  5. Tailored voltage waveform capacitively coupled plasmas in electronegative gases: frequency dependence of asymmetry effects

    NASA Astrophysics Data System (ADS)

    Schüngel, E.; Korolov, I.; Bruneau, B.; Derzsi, A.; Johnson, E.; O’Connell, D.; Gans, T.; Booth, J.-P.; Donkó, Z.; Schulze, J.

    2016-07-01

    Capacitively coupled radio frequency plasmas operated in an electronegative gas (CF4) and driven by voltage waveforms composed of four consecutive harmonics are investigated for different fundamental driving frequencies using PIC/MCC simulations and an analytical model. As has been observed previously for electropositive gases, the application of peak-shaped waveforms (that are characterized by a strong amplitude asymmetry) results in the development of a DC self-bias due to the electrical asymmetry effect (EAE), which increases the energy of ions arriving at the powered electrode. In contrast to the electropositive case (Korolov et al 2012 J. Phys. D: Appl. Phys. 45 465202) the absolute value of the DC self-bias is found to increase as the fundamental frequency is reduced in this electronegative discharge, providing an increased range over which the DC self-bias can be controlled. The analytical model reveals that this increased DC self-bias is caused by changes in the spatial profile and the mean value of the net charge density in the grounded electrode sheath. The spatio-temporally resolved simulation data show that as the frequency is reduced the grounded electrode sheath region becomes electronegative. The presence of negative ions in this sheath leads to very different dynamics of the power absorption of electrons, which in turn enhances the local electronegativity and plasma density via ionization and attachment processes. The ion flux to the grounded electrode (where the ion energy is lowest) can be up to twice that to the powered electrode. At the same time, while the mean ion energies at both electrodes are quite different, their ratio remains approximately constant for all base frequencies studied here.

  6. Trench and hole patterning with EUV resists using dual frequency capacitively coupled plasma (CCP)

    NASA Astrophysics Data System (ADS)

    Feurprier, Yannick; Lutker-Lee, Katie; Rastogi, Vinayak; Matsumoto, Hiroie; Chiba, Yuki; Metz, Andrew; Kumar, Kaushik; Beique, Genevieve; Labonte, Andre; Labelle, Cathy; Mignot, Yann; Hamieh, Bassem; Arnold, John

    2015-03-01

    Patterning at 10 nm and sub-10 nm technology nodes is one of the key challenges for the semiconductor industry. Several patterning techniques are under investigation to enable the aggressive pitch requirements demanded by the logic technologies. EUV based patterning is being considered as a serious candidate for the sub-10nm nodes. As has been widely published, a new technology like EUV has its share of challenges. One of the main concerns with EUV resists is that it tends to have a lower etch selectivity and worse LER/LWR than traditional 193nm resists. Consequently the characteristics of the dry etching process play an increasingly important role in defining the outcome of the patterning process. In this paper, we will demonstrate the role of the dual-frequency Capacitively Coupled Plasma (CCP) in the EUV patterning process with regards to improving LER/LWR, resist selectivity and CD tunability for holes and line patterns. One of the key knobs utilized here to improve LER and LWR, involves superimposing a negative DC voltage in RF plasma at one of the electrodes. The emission of ballistic electrons, in concert with the plasma chemistry, has shown to improve LER and LWR. Results from this study along with traditional plasma curing methods will be presented. In addition to this challenge, it is important to understand the parameters needed to influence CD tunability and improve resist selectivity. Data will be presented from a systematic study that shows the role of various plasma etch parameters that influence the key patterning metrics of CD, resist selectivity and LER/LWR. This work was performed by the Research Alliance Teams at various IBM Research and Development Facilities.

  7. Trace determination of perchlorate using electromembrane extraction and capillary electrophoresis with capacitively coupled contactless conductivity detection.

    PubMed

    Kiplagat, Isaac K; Doan, Thi Kieu Oanh; Kubáň, Pavel; Boček, Petr

    2011-11-01

    Electromembrane extraction (EME) and CE with capacitively coupled contactless conductivity detection (CE-C(4) D) was applied to rapid and sensitive determination of perchlorate in drinking water and environmental samples. Porous polypropylene hollow fiber impregnated with 1-heptanol acted as a supported liquid membrane (SLM) and perchlorate was transported and preconcentrated in the fiber lumen on application of electric field. High selectivity of perchlorate determination and its baseline separation from major inorganic anions was achieved in CE-C(4) D using background electrolyte solution consisting of 7.5 mM L-histidine and 40 mM acetic acid at pH 4.1. The analytical method showed excellent parameters in terms of reproducibility; RSD values for migration times and peak areas at a spiked concentration of 15 μg/L of perchlorate (US EPA recommended limit for drinking water) were below 0.2 and 8.7%, respectively, in all examined water samples. Linear calibration curves were obtained for perchlorate in the concentration range 1-100 μg/L (r(2) ≥0.999) with limits of detection at 1 μg/L for tap water and at 0.25-0.35 μg/L for environmental and bottled potable water samples. Recoveries at 15 μg/L of perchlorate were between 95.9 and 106.7% with minimum and maximum recovery values for snow and bottled potable water samples, respectively.

  8. Energy distribution of electron flux at electrodes in a low pressure capacitively coupled plasma

    NASA Astrophysics Data System (ADS)

    Rauf, Shahid; Dorf, Leonid; Kenney, Jason; Collins, Ken

    2013-01-01

    A one-dimensional particle-in-cell (PIC) model is used to examine the energy distribution of electron flux at electrodes [labeled ge(ɛ,t), where ɛ is energy and t is time] in a low pressure 60 MHz capacitively coupled Ar discharge. The effect of gas pressure and an auxiliary DC voltage on ge(ɛ,t) is also investigated. It is found that the electrons only leave the plasma for a short time period during the radio-frequency (RF) cycle when the sheath collapses at the electrode. Furthermore, majority of the exiting electrons have energies below 10 eV with a distribution ge(ɛ,t) that is narrow in both energy and time. At relatively high pressures (≥4.67 Pa for the conditions considered), the relationship between the time-average distribution ge(ɛ) and electron temperature in the plasma (Te) can be easily established. Below 4.67 Pa, kinetic effects become important, making it difficult to interpret ge(ɛ) in terms of Te. At low pressures, ge(ɛ,t) is found to broaden in both energy and time except for a narrow pressure range around 1.2 Pa where the distribution narrows temporally. These low pressure kinetic phenomena are observed when the electrons can be accelerated by expanding sheaths to speeds that allow them to traverse the inter-electrode distance quickly (<1.5 RF cycles for conditions considered) and when electrons undergo few collisions during this excursion. The mean energy of exiting electrons increases with decreasing gas pressure, especially below 1.0 Pa, due to higher Te and secondary electrons retaining a larger fraction of the energy they gained during initial sheath acceleration. For the relatively small DC voltages examined (|Vdc|/Vrf ≤ 0.15), the application of a negative DC voltage on an electrode decreases the electron flux there but has a weak impact on the ge profile.

  9. High energy electron fluxes in dc-augmented capacitively coupled plasmas I. Fundamental characteristics

    NASA Astrophysics Data System (ADS)

    Wang, Mingmei; Kushner, Mark J.

    2010-01-01

    Power deposition from electrons in capacitively coupled plasmas (CCPs) has components from stochastic heating, Joule heating, and from the acceleration of secondary electrons through sheaths produced by ion, electron, or photon bombardment of electrodes. The sheath accelerated electrons can produce high energy beams which, in addition to producing excitation and ionization in the gas can penetrate through the plasma and be incident on the opposite electrode. In the use of CCPs for microelectronics fabrication, there may be an advantage to having these high energy electrons interact with the wafer. To control the energy and increase the flux of the high energy electrons, a dc bias can be externally imposed on the electrode opposite the wafer, thereby producing a dc-augmented CCP (dc-CCP). In this paper, the characteristics of dc-CCPs will be discussed using results from a computational study. We found that for a given rf bias power, beams of high energy electrons having a narrow angular spread (<1°) can be produced incident on the wafer. The maximum energy in the high energy electron flux scales as ɛmax=-Vdc+Vrf+Vrf0, for a voltage on the dc electrode of Vdc, rf voltage of Vrf, and dc bias on the rf electrode of Vrf0. The dc current from the biased electrode must return to ground through surfaces other than the rf electrode and so seeks out a ground plane, typically the side walls. If the side wall is coated with a poorly conducting polymer, the surface will charge to drive the dc current through.

  10. Heating mode transition in capacitively coupled CF4 discharges: comparison of experiments with simulations

    NASA Astrophysics Data System (ADS)

    Liu, Gang-Hu; Liu, Yong-Xin; Wen, De-Qi; Wang, You-Nian

    2015-06-01

    The electron heating mode transitions in capacitively coupled CF4 discharges were studied by synergistically using two diagnostic methods in combination with Particle-in-Cell/Monte Carlo collision (PIC/MCC) simulations. Based on the method of phase resolved optical emission spectroscopy of trace rare gas, the spatiotemporal evolutions of energetic electrons were presented. The time-average electron density at the discharge center was measured by using a hairpin probe. All the experimental results were compared with those obtained from PIC/MCC simulations. Two different electron heating modes were observed depending on the discharge conditions: (1) the α mode (or electropositive mode), in which the electron heating maximum occurs near the sheath boundary, dominated by the sheath electric field during its expansion phase, (2) the drift-ambipolar (DA) mode (or electronegative mode), in which the electron heating maxima occur inside the entire bulk plasma and near the collapsing sheath edge, dominated by the drift field inside the bulk and the ambipolar fields near the collapsing sheath edge, respectively. The transitions between the two modes were presented when changing the rf power, working pressure and driving frequency. By increasing the power, the heating mode experiences a transition from DA to α mode. This is ascribed to the fact that at high powers, the sheath heating is enhanced, leading to a drastic decrease in the electronegativity, and consequently the DA electric field is significantly reduced. By increasing the pressure, a heating mode transition from a pure α mode, then a combination of α and DA modes, finally into a DA mode is induced. We found that the mode transition is much more sensitive to the change of working pressure than that of rf power. When increasing the pressure, there is an evident enhancement in the electron attachment, which can generate the negative ions and deplete the electrons, resulting in a higher electronegativity as well as

  11. CAPACITIVE COUPLING ELECTRIC FIELDS IN THE TREATMENT OF VERTEBRAL COMPRESSION FRACTURES.

    PubMed

    Piazzolla, A; Solarino, G; Bizzoca, D; Garofalo, N; Dicuonzo, F; Setti, S; Moretti, B

    2015-01-01

    Positive effects of Capacitive Coupling Electric Field (CCEF) stimulation are described for several orthopedic indications such as the healing of recent fractures, non-unions and spinal fusion, due to the capacity to involve the up-regulation of osteopromotive factors. In vitro studies on MC3T3-E1 bone cells showed that CCEF acts opening the plasma membrane voltage gated calcium channels, thus increasing the cytosolic calcium concentration and the phospholipase A2 (PLA2) activity. Cytosolic calcium activates the calmodulin pathway, thus resulting in an up-regulated expression of osteogenic genes, such as transforming growth factor-β superfamily genes (TGF-β1, -β2 -β3, bone morphogenetic protein-2 and -4), fibroblast growth factor (FGF)-2, osteocalcin (BGP) and alkaline phosphatase (ALP). PLA2 acts increasing the synthesis of Prostaglandin E2 (PGE2), which promotes osteogenesis by raising the cellular L-ascorbic acid uptake through the membrane carrier sodium vitamin C transporter-2 (SVCT-2). In vivo, Brighton et al. in a castration-induced osteoporosis animal model, demonstrated that CCEF was able to restore bone mass/unit volume in the rat vertebral body. To investigate the role of CCEF stimulation in vertebral bone marrow edema (VBME) its percentage was assessed in 24 patients with 25 acute vertebral compression fractures (VCFs) conservatively treated with CCEF (group A) or without CCEF (group B) using serial MR imaging follow-up at 0, 30, 60, 90 days. Pain and quality of life were assessed by visual analog scale (VAS) and Oswestry Low Back Disability Index (ODI) in the same periods. At 90 day follow-up the complete resolution of VBME was found only in group A (p=0.0001). A significant improvement of VAS (p=0.007) and ODI (p=0.002) was also observed in group A. This preliminary observational study shows that patients treated with CCEF stimulation present an improvement of clinical symptoms with faster fracture healing and a complete VBME resolution. PMID

  12. Interface and permittivity simultaneous reconstruction in electrical capacitance tomography based on boundary and finite-elements coupling method.

    PubMed

    Ren, Shangjie; Dong, Feng

    2016-06-28

    Electrical capacitance tomography (ECT) is a non-destructive detection technique for imaging the permittivity distributions inside an observed domain from the capacitances measurements on its boundary. Owing to its advantages of non-contact, non-radiation, high speed and low cost, ECT is promising in the measurements of many industrial or biological processes. However, in the practical industrial or biological systems, a deposit is normally seen in the inner wall of its pipe or vessel. As the actual region of interest (ROI) of ECT is surrounded by the deposit layer, the capacitance measurements become weakly sensitive to the permittivity perturbation occurring at the ROI. When there is a major permittivity difference between the deposit and the ROI, this kind of shielding effect is significant, and the permittivity reconstruction becomes challenging. To deal with the issue, an interface and permittivity simultaneous reconstruction approach is proposed. Both the permittivity at the ROI and the geometry of the deposit layer are recovered using the block coordinate descent method. The boundary and finite-elements coupling method is employed to improve the computational efficiency. The performance of the proposed method is evaluated with the simulation tests. This article is part of the themed issue 'Supersensing through industrial process tomography'. PMID:27185960

  13. Interface and permittivity simultaneous reconstruction in electrical capacitance tomography based on boundary and finite-elements coupling method.

    PubMed

    Ren, Shangjie; Dong, Feng

    2016-06-28

    Electrical capacitance tomography (ECT) is a non-destructive detection technique for imaging the permittivity distributions inside an observed domain from the capacitances measurements on its boundary. Owing to its advantages of non-contact, non-radiation, high speed and low cost, ECT is promising in the measurements of many industrial or biological processes. However, in the practical industrial or biological systems, a deposit is normally seen in the inner wall of its pipe or vessel. As the actual region of interest (ROI) of ECT is surrounded by the deposit layer, the capacitance measurements become weakly sensitive to the permittivity perturbation occurring at the ROI. When there is a major permittivity difference between the deposit and the ROI, this kind of shielding effect is significant, and the permittivity reconstruction becomes challenging. To deal with the issue, an interface and permittivity simultaneous reconstruction approach is proposed. Both the permittivity at the ROI and the geometry of the deposit layer are recovered using the block coordinate descent method. The boundary and finite-elements coupling method is employed to improve the computational efficiency. The performance of the proposed method is evaluated with the simulation tests. This article is part of the themed issue 'Supersensing through industrial process tomography'.

  14. Branch structure of IV-characteristics in the capacitively coupled Josephson junctions model with the diffusion current

    NASA Astrophysics Data System (ADS)

    Shukrinov, Yu. M.; Mahfouzi, F.; Seidel, P.

    2007-09-01

    We have solved numerically a system of dynamical equations for the gauge-invariant phase differences between superconducting layers for a stack of N intrinsic junctions and obtained a total branch structure in the current-voltage characteristics (IVC) of the stack. The coupling dependence of the branch’s slopes is investigated and demonstrated that the equidistance of the branch structure in capacitively coupled Josephson junctions (CCJJ) model is broken at small values of coupling parameter. Changes in the parameters of the boundary conditions and the use of periodic boundary conditions do not affect this result. In the framework of the CCJJ model with the diffusion current we simulate an experiment and obtain the IV-characteristic with equidistant branch structure at different values of model parameters.

  15. The discharge mode transition and O(5p1) production mechanism of pulsed radio frequency capacitively coupled plasma

    NASA Astrophysics Data System (ADS)

    Liu, X. Y.; Hu, J. T.; Liu, J. H.; Xiong, Z. L.; Liu, D. W.; Lu, X. P.; Shi, J. J.

    2012-07-01

    The discharge mode transition from uniform plasma across the gas gap to the α mode happens at the rising phase of the pulsed radio frequency capacitively coupled plasma (PRF CCP). This transition is attributed to the fast increasing stochastic heating at the edge of sheath. In the second stage with the stable current and voltage amplitude, the consistency between experimental and numerical spatial-temporal 777 nm emission profile suggests that He* and He2* dominate the production of O(5p1) through dissociation and excitation of O2. Finally, the sterilization efficiency of PRF CCP is found to be higher than that of plasma jet.

  16. Capacitively coupled resistivity survey of the levee surrounding the Omaha Public Power District Nebraska City Power Plant, June 2011

    USGS Publications Warehouse

    Burton, Bethany L.; Cannia, James C.

    2011-01-01

    This report is a release of digital data from a capacitively coupled resistivity survey conducted on June 13, 2011, on the flood-protection levees surrounding the Omaha Public Power District Nebraska City power plant. The U.S. Geological Survey Crustal Geophysics and Geochemistry Science Center and the Nebraska Water Science Center performed the survey in response to a flood on the Missouri River. A single line of resistivity profiling was completed along the center line of the section of levee 573 that surrounds the power plant.

  17. On the scaling of rf and dc self-bias voltages with pressure in electronegative capacitively coupled plasmas

    SciTech Connect

    Agarwal, Ankur; Dorf, Leonid; Rauf, Shahid; Collins, Ken

    2012-03-15

    Higher gas densities and lower diffusion losses at higher operating pressures typically lead to increased charged species densities (and hence flux) for a constant power deposition in capacitively coupled plasmas (CCP). As a result, one would expect that the bias radio-frequency (rf) voltage required to deposit a given power in a CCP reactor decreases with increasing operating pressure. These observations may not hold true in multiple frequency CCPs, commonly used for dielectric etching in microelectronics fabrication, due to nonlinear interactions between the rf sources. Wafer-based measurements of the rf and self-generated direct current (dc) bias voltages in a dual-frequency capacitively coupled electronegative plasma were made, which indicate that the rf and dc voltages vary nonmonotonically with pressure. These experimental results are presented in this paper and a computational plasma model is used to explain the experimental observations for varying 60 MHz and 13 MHz powers in the Ar/CF{sub 4}/CHF{sub 3} plasma over a pressure range of 25 to 400 mTorr. The authors found that while the ion density increases with pressure, the increase is most dominant near the electrode with the high frequency source (60 MHz). The rf and dc bias voltages are ultimately influenced by both charged species density magnitudes and spatial profiles.

  18. A capacitive-coupled ground resistivity system for engineering and environmental applications: Results of two Canadian field tests

    SciTech Connect

    Douma, M.; Hunter, J.A.; Timofeev, V.M.; Rogozinski, A.W.

    1994-12-31

    Ground resistivity conditions in a variety of geological environments were measured using a technique that odes not rely on galvanic contact between the sensors and the terrain. The capacitive-coupling method converts a current applied through one pair of antennas and a voltage potential received through another set of antennas into apparent resistivity using a particular constant which is dependent upon the geometry of the antenna arrays. The method supports rapid data acquisition, and because contact resistance problems are obviated, surveys in very resistive conditions (> 10,000 ohm-m) can be conducted. Originally a Russian development, used in routine permafrost mapping along pipeline routes and at well-sites in Siberia, a version of the capacitive-coupled resistivity (CCR) system, called RUSCAN, is being developed by a Canadian firm, Androtex, Ltd. The development program is supported by the All-Russian Institute for Hydrogeology and Engineering Geology in Moscow and the Industrial Partners Program of the Geological Survey of Canada. Case studies in a variety of geological environments have been used to evaluate the new system, comparing results from electromagnetic, D.C. resistivity, drilling results, and borehole geophysics.

  19. Beyond the Binary: Trans-Negotiations in Couple and Family Therapy.

    PubMed

    Giammattei, Shawn V

    2015-09-01

    Dualistic notions about gender and sexuality have permeated the field of couple and family therapy. These binary constructions have been limiting for everyone, especially those who fall outside the male/female dichotomy. This article examines the impact of these binary notions, especially on transgender and gender-creative individuals, couples, and families. Current theory and research in the field as they relate to gender identity, sexuality, and gender minority stress in couples and families are presented. Case examples are used to illustrate affirmative approaches to treatment issues such as coming out, safety, grief and loss, redefining relationships, and social/medical transitions that may arise for transgender or gender nonconforming (TGNC) individuals, couples, and families.

  20. PHYSICS OF GASES, PLASMAS, AND ELECTRIC DISCHARGES: CHF3 Dual-Frequency Capacitively Coupled Plasma by Optical Emission Spectroscopy

    NASA Astrophysics Data System (ADS)

    Xu, Yi-Jun; Ye, Chao; Huang, Xiao-Jiang; Yuan, Jing; Xing, Zhen-Yu; Ning, Zhao-Yuan

    2008-08-01

    We investigate the intermediate gas phase in the CHF3 13.56 MHz/2 MHz dual-frequency capacitively couple plasma (CCP) for the SiCOH low dielectric constant (low-k) film etching, and the effect of 2 MHz power on radicals concentration. The major dissociation reactions of CHF3 in 13.56MHz CCP are the low dissociation bond energy reactions, which lead to the low F and high CF2 concentrations. The addition of 2 MHz power can raise the probability of high dissociation bond energy reactions and lead to the increase of F concentration while keeping the CF2 concentration almost a constant, which is of advantage to the SiCOH low-k films etching. The radical spatial uniformity is dependent on the power coupling of two sources. The increase of 2 MHz power leads to a poor uniformity, however, the uniformity can be improved by increasing 13.56 MHz power.

  1. Numerical investigation on fundamental properties in capacitively-coupled methane plasmas for deposition of diamond-like carbon films

    NASA Astrophysics Data System (ADS)

    Oda, Akinori; Kousaka, Hiroyuki

    2012-10-01

    Capacitively-coupled methane (CH4) plasmas for deposition of diamond-like carbon films have been simulated using a self-consistent one-dimensional fluid model, incorporating the mass balance equations for electrons, ions, radicals and non-radicals, the electron energy balance equation, coupled with the Poisson equation. Despite of low-pressure CH4 gas condition, many positive-ion species, such as C2H4^+, CH4^+, C2H2^+, CH5^+ etc., have been found in the plasmas. The non-radical neutrals, such as C2H4, C3H8, C2H2 and C2H6, have also found with higher densities comparable to the source gas density. This result indicates that this complexity of background gas in CH4 plasmas is strongly affected to the electron energy distribution function, which is important for the determination of plasmas properties.

  2. Disc-jet-wind coupling in black hole binaries, and other stories

    NASA Astrophysics Data System (ADS)

    Fender, R.

    2016-05-01

    In this article, I briefly review our current understanding of the phenomenological connections between accretion flows, jets and winds in black hole binaries. I further highlight a couple of topical and important areas which need the attention of the community and should lead to interesting astrophysics.

  3. Experimental Observation and Computational Analysis of Striations in Electronegative Capacitively Coupled Radio-Frequency Plasmas

    NASA Astrophysics Data System (ADS)

    Liu, Yong-Xin; Schüngel, Edmund; Korolov, Ihor; Donkó, Zoltán; Wang, You-Nian; Schulze, Julian

    2016-06-01

    Self-organized spatial structures in the light emission from the ion-ion capacitive rf plasma of a strongly electronegative gas (CF4 ) are observed experimentally for the first time. Their formation is analyzed and understood based on particle-based kinetic simulations. These "striations" are found to be generated by the resonance between the driving radio frequency and the eigenfrequency of the ion-ion plasma (derived from an analytical model) that establishes a modulation of the electric field, the ion densities, as well as the energy gain and loss processes of electrons in the plasma. The growth of the instability is followed by the numerical simulations.

  4. Experimental Observation and Computational Analysis of Striations in Electronegative Capacitively Coupled Radio-Frequency Plasmas.

    PubMed

    Liu, Yong-Xin; Schüngel, Edmund; Korolov, Ihor; Donkó, Zoltán; Wang, You-Nian; Schulze, Julian

    2016-06-24

    Self-organized spatial structures in the light emission from the ion-ion capacitive rf plasma of a strongly electronegative gas (CF_{4}) are observed experimentally for the first time. Their formation is analyzed and understood based on particle-based kinetic simulations. These "striations" are found to be generated by the resonance between the driving radio frequency and the eigenfrequency of the ion-ion plasma (derived from an analytical model) that establishes a modulation of the electric field, the ion densities, as well as the energy gain and loss processes of electrons in the plasma. The growth of the instability is followed by the numerical simulations. PMID:27391730

  5. The coupled effect of tides and stellar winds on the evolution of compact binaries

    NASA Astrophysics Data System (ADS)

    Repetto, Serena; Nelemans, Gijs

    2014-10-01

    We follow the evolution of compact binaries under the coupled effect of tides and stellar winds until the onset of Roche lobe overflow. These binaries contain a compact object (either a black hole, a neutron star or a planet) and a stellar component. We integrate the full set of tidal equations, which are based on Hut's model for tidal evolution, and we couple them with the angular momentum loss in a stellar wind. Our aim is twofold. First, we wish to highlight some interesting evolutionary outcomes of the coupling. When tides are coupled with a non-massive stellar wind, one interesting outcome is that in certain types of binaries, the stellar spin tends to reach a quasi-equilibrium state, where the effects of tides and wind are counteracting each other. When tides are coupled with a massive wind, we parametrize the evolution in terms of the decoupling radius, at which the wind decouples from the star. Even for small decoupling radii, this wind braking can drive systems on the main sequence to Roche lobe overflow that otherwise would fail to do so. Our second aim is to inspect whether simple time-scale considerations are a good description of the evolution of the systems. We find that simple time-scale considerations, which rely on neglecting the coupling between tides and stellar winds, do not accurately represent the true evolution of compact binaries. The outcome of the coupled evolution of the rotational and orbital elements can strongly differ from simple time-scale considerations, as already pointed out by Barker and Ogilvie in the case of short-period planetary systems.

  6. Rabi-coupled countersuperflow in binary Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Usui, Ayaka; Takeuchi, Hiromitsu

    2015-06-01

    We show theoretically that periodic density patterns are stabilized in two counterpropagating Bose-Einstein condensates of atoms in different hyperfine states under Rabi coupling. In the presence of coupling, the relative velocity between the two components is localized around density depressions in quasi-one-dimensional systems. When the relative velocity is sufficiently small, the periodic pattern reduces to a periodic array of topological solitons as kinks of the relative phase. According to our variational and numerical analyses, the soliton solution is well characterized by the soliton width and density depression. We demonstrate the dependence of the depression and width on the Rabi frequency and the coupling constant of the intercomponent density-density interactions. The periodic pattern of the relative phase transforms continuously from a soliton array to a sinusoidal pattern as the period becomes smaller than the soliton width. These patterns become unstable when the localized relative velocity exceeds a critical value. The stability-phase diagram of this system is evaluated with a stability analysis of countersuperflow, by taking into account the finite-size effect owing to the density depression.

  7. Modulational instability in binary spin-orbit-coupled Bose-Einstein condensates

    NASA Astrophysics Data System (ADS)

    Bhat, Ishfaq Ahmad; Mithun, T.; Malomed, B. A.; Porsezian, K.

    2015-12-01

    We study modulation instability (MI) of flat states in two-component spin-orbit-coupled (SOC) Bose-Einstein condensates (BECs) in the framework of coupled Gross-Pitaevskii equations for two components of the pseudospinor wave function. The analysis is performed for equal densities of the components. Effects of the interaction parameters, Rabi coupling, and SOC on the MI are investigated. In particular, the results demonstrate that the SOC strongly alters the commonly known MI (immiscibility) condition, g122>g1g2 , for the binary superfluid with coefficients g1 ,2 and g12 of the intra- and interspecies repulsive interactions. In fact, the binary BEC is always subject to the MI under the action of the SOC, which implies that the ground state of the system is plausibly represented by a striped phase.

  8. Enhancing capacitive deionization performance of electrospun activated carbon nanofibers by coupling with carbon nanotubes.

    PubMed

    Dong, Qiang; Wang, Gang; Wu, Tingting; Peng, Senpei; Qiu, Jieshan

    2015-05-15

    Capacitive deionization (CDI) is an alternative, effective and environmentally friendly technology for desalination of brackish water. The performance of the CDI device is highly determined by the electrode materials. In this paper, a composite of carbon nanotubes (CNTs) embedded in activated carbon nanofiber (ACF) was prepared by a direct co-electrospinning way and subsequent CO2 activation. The introduction of CNTs can greatly improve the conductivity while the CO2-mediated activation can render the final product with high porosity. As such, the hybrid structure can provide an excellent storage space and pathways for ion adsorption and conduction. When evaluated as electrode materials for CDI, the as-prepared CNT/ACF composites with higher electrical conductivity and mesopore ratios exhibited higher electrosorption capacity and good regeneration performance in comparison with the pure ACF.

  9. Capacitive deionization coupled with microbial fuel cells to desalinate low-concentration salt water.

    PubMed

    Yuan, Lulu; Yang, Xufei; Liang, Peng; Wang, Lei; Huang, Zheng-Hong; Wei, Jincheng; Huang, Xia

    2012-04-01

    A new technology (CDI-MFC) that combined capacitive deionization (CDI) and microbial fuel cell (MFC) was developed to treat low-concentration salt water with NaCl concentration of 60mg/L. The water desalination rate was 35.6mg/(Lh), meanwhile the charge efficiency was 21.8%. Two desorption modes were investigated: discharging (DC) mode and short circuit (SC) mode. The desalination rate in the DC mode was 200.6±3.1mg/(Lh), 47.8% higher than that in the SC mode [135.7±15.3mg/(Lh)]. The average current in the DC mode was also much higher than that of the SC mode. The energy stored in the CDI cell has been reused to enhance the electron production of MFC by the discharging desorption mode (DC mode), which offers an approach to recover the electrostatic energy in the CDI cell.

  10. Strong ionization asymmetry in a geometrically symmetric radio frequency capacitively coupled plasma induced by sawtooth voltage waveforms.

    PubMed

    Bruneau, Bastien; Gans, Timo; O'Connell, Deborah; Greb, Arthur; Johnson, Erik V; Booth, Jean-Paul

    2015-03-27

    The ionization dynamics in geometrically symmetric parallel plate capacitively coupled plasmas driven by radio frequency tailored voltage waveforms is investigated using phase resolved optical emission spectroscopy (PROES) and particle-in-cell (PIC) simulations. Temporally asymmetric waveforms induce spatial asymmetries and offer control of the spatiotemporal dynamics of electron heating and associated ionization structures. Sawtooth waveforms with different rise and fall rates are employed using truncated Fourier series approximations of an ideal sawtooth. Experimental PROES results obtained in argon plasmas are compared with PIC simulations, showing excellent agreement. With waveforms comprising a fast voltage drop followed by a slower rise, the faster sheath expansion in front of the powered electrode causes strongly enhanced ionization in this region. The complementary waveform causes an analogous effect in front of the grounded electrode. PMID:25860749

  11. Characterization of argon/air atmospheric pressure capacitively coupled radio frequency dielectric barrier discharge regarding parasitic capacitor at 13.56 MHz

    NASA Astrophysics Data System (ADS)

    Sohbatzadeh, Farshad; Mirzanejhad, Saeed; Mahdavi, Hoda; Omidi, Zahra

    2012-11-01

    In this paper, uniform argon glow discharge at atmospheric pressure in a diffuse mode driven by a 300-W radio-frequency (13.56 MHz) power supply based on dielectric barrier discharge was investigated. In this work, the effect of the parasitic capacitor on the electrical characteristics of the capacitively coupled atmospheric pressure plasma was investigated. It was revealed that more than half of the RF current is parasitic in our system as a characteristic of the capacitively coupled plasma. It was also proved that the discharge resistance and sheath capacitance increase at higher input powers while the impedance decreases. In order to recognize plasma, optical emission spectroscopy apparatus was used. Argon, oxygen, copper, and nitrogen spectrum lines were diagnosed. The plasma gas temperature and electronic excitation temperature were investigated showing a non-equilibrium discharge.

  12. Gravitational waveforms from unequal-mass binaries with arbitrary spins under leading order spin-orbit coupling

    SciTech Connect

    Tessmer, Manuel

    2009-12-15

    This paper generalizes the structure of gravitational waves from orbiting spinning binaries under leading order spin-orbit coupling, as given in the work by Koenigsdoerffer and Gopakumar [Phys. Rev. D 71, 024039 (2005)] for single-spin and equal-mass binaries, to unequal-mass binaries and arbitrary spin configurations. The orbital motion is taken to be quasicircular and the fractional mass difference is assumed to be small against one. The emitted gravitational waveforms are given in analytic form.

  13. Kinetic interpretation of resonance phenomena in low pressure capacitively coupled radio frequency plasmas

    NASA Astrophysics Data System (ADS)

    Wilczek, Sebastian; Trieschmann, Jan; Eremin, Denis; Brinkmann, Ralf Peter; Schulze, Julian; Schuengel, Edmund; Derzsi, Aranka; Korolov, Ihor; Hartmann, Peter; Donkó, Zoltán; Mussenbrock, Thomas

    2016-06-01

    Low pressure capacitive radio frequency (RF) plasmas are often described by equivalent circuit models based on fluid approaches that predict the self-excitation of resonances, e.g., high frequency oscillations of the total current in asymmetric discharges, but do not provide a kinetic interpretation of these effects. In fact, they leave important questions open: How is current continuity ensured in the presence of energetic electron beams generated by the expanding sheaths that lead to a local enhancement of the conduction current propagating through the bulk? How do the beam electrons interact with cold bulk electrons? What is the kinetic origin of resonance phenomena? Based on kinetic simulations, we find that the energetic beam electrons interact with cold bulk electrons (modulated on a timescale of the inverse local electron plasma frequency) via a time dependent electric field outside the sheaths. This electric field is caused by the electron beam itself, which leaves behind a positive space charge, that attracts cold bulk electrons towards the expanding sheath. The resulting displacement current ensures current continuity by locally compensating the enhancement of the conduction current. The backflow of cold electrons and their interaction with the nonlinear plasma sheath cause the generation of multiple electron beams during one phase of sheath expansion and contribute to a strongly non-sinusoidal RF current. These kinetic mechanisms are the basis for a fundamental understanding of the electron power absorption dynamics and resonance phenomena in such plasmas, which are found to occur in discharges of different symmetries including perfectly symmetric plasmas.

  14. Ternary and coupled binary zinc tin oxide nanopowders: Synthesis, characterization, and potential application in photocatalytic processes

    SciTech Connect

    Ivetić, T.B.; Finčur, N.L.; Đačanin, Lj. R.; Abramović, B.F.; Lukić-Petrović, S.R.

    2015-02-15

    Highlights: • Mechanochemically synthesized nanocrystalline zinc tin oxide (ZTO) powders. • Photocatalytic degradation of alprazolam in the presence of ZTO water suspensions. • Coupled binary ZTO exhibits enhanced photocatalytic activity compared to ternary ZTO. - Abstract: In this paper, ternary and coupled binary zinc tin oxide nanocrystalline powders were prepared via simple solid-state mechanochemical method. X-ray diffraction, scanning electron microscopy, Raman and reflectance spectroscopy were used to study the structure and optical properties of the obtained powder samples. The thermal behavior of zinc tin oxide system was examined through simultaneous thermogravimetric-differential scanning calorimetric analysis. The efficiencies of ternary (Zn{sub 2}SnO{sub 4} and ZnSnO{sub 3}) and coupled binary (ZnO/SnO{sub 2}) zinc tin oxide water suspensions in the photocatalytic degradation of alprazolam, short-acting anxiolytic of the benzodiazepine class of psychoactive drugs, under UV irradiation were determined and compared with the efficiency of pure ZnO and SnO{sub 2}.

  15. Current response for a single redox moiety trapped in a closed generator-collector system: the role of capacitive coupling.

    PubMed

    Feldberg, Stephen W; Edwards, Martin A

    2015-04-01

    A theoretical model is proposed to describe the steady-state average limiting current associated with a single redox moiety (ox or red) trapped in a closed generator-collector system along with excess supporting electrolyte. By "closed" we mean that neither solvent nor solutes can enter or leave the system. The potential difference, EOE - ERE, between the oxidizing electrode (OE) and the reducing electrode (RE) is maintained constant with the values of EOE and ERE chosen so that the operative faradaic electrode processes are very fast, i.e., red = ox + nETe(-) (kox = ∞) at the OE and ox + nETe(-) = red (kred = ∞) at the RE. Because there is only a single redox moiety the faradaic process occurs at only one electrode at a time while current at the other electrode is purely capacitive (we refer to this as capacitive coupling). We propose that a two-step process is required to transfer nETqe coulombs (qe is the absolute value of the elemental electronic charge). The first step is associated with diffusion (approximated as a random walk) of a single red moiety to the OE where it is oxidized to ox with a concomitant transfer of qstep1 (= nETqe/(1 + AOECOE/ARECRE)) coulombs; the second step is associated with the diffusion (random walk) of the newly formed single ox moiety to the RE with the concomitant transfer of qstep2 (= nETqe/(1 + ARECRE/AOECOE)) coulombs (ARE,AOE andCRE,COEare the areas (cm(2)) and differential capacitances (farads cm(-2)) of the corresponding electrodes). The total charge transferred in the two steps is nETqe(= qstep1 + qstep2). Transport of the redox moiety from one electrode to the other is accomplished by a random walk. The probability density function (pdf) and cumulative density function (CDF) for the duration of a full redox cycle are presented as the analytical solution to a 1-dimensional bounded random-walk problem (confirmed by numerical simulation). These show that tfull, the average time for the full redox cycle (step 1 + step 2

  16. Simultaneous determination of atenolol and amiloride by capillary electrophoresis with capacitively coupled contactless conductivity detection (C4D).

    PubMed

    AL Azzam, Khaldun M; Aboul-Enein, Hassan Y

    2013-01-01

    Capillary electrophoresis coupled with a capacitively coupled contactless conductivity detector (CE-C(4)D) has been employed for the determination of the β-blocker drugs (atenolol and amiloride) in pharmaceutical formulations. 150 mM acetic acid was used as background electrolyte. The influence of several factors (detector excitation voltage and frequency, buffer concentration, applied voltage, capillary temperature, and injection time) was studied. Non-UV absorbing L-valine was used as an internal standard; the analytes were all separated in less than 7 min. The separation was carried out in normal polarity mode at 28 °C, 25 kV, and using hydrodynamic injection (25 s). The separation was effected in a bare fused-silica capillary 75 μm × 52 cm. The CE-C(4)D method was validated with respect to linearity, limit of detection and quantification, accuracy, precision, and selectivity. Calibration curves were linear over the range 5-250 μg mL(-1) for the studied analytes. The relative standard deviations of intra- and inter-day precisions of migration times and corrected peak areas were less than 6.0%. The method showed good precision and accuracy and was successfully applied to the simultaneous determination of the β-blocker drugs in different pharmaceutical tablets.

  17. Arsenic and antimony determination in non- and biodegradable materials by hydride generation capacitively coupled plasma microtorch optical emission spectrometry.

    PubMed

    Mihaltan, Alin I; Frentiu, Tiberiu; Ponta, Michaela; Petreus, Dorin; Frentiu, Maria; Darvasi, Eugen; Marutoiu, Constantin

    2013-05-15

    A sensitive method using a miniature analytical system with a capacitively coupled plasma microtorch (25 W, 13.56 MHz, 0.4 l min(-1) Ar) was developed and evaluated for the determination of As and Sb in recyclable plastics and biodegradable materials by hydride generation optical emission spectrometry. Given their toxicity, As and Sb should be subject to monitoring in such materials despite not being included within the scope of Restriction of Hazardous Substances Directive. The advantages of the proposed approach are better detection limits and lower analysis cost relative to conventional systems based on inductively coupled plasma optical emission and flame atomic absorption spectrometry with/without derivatization. Samples were subjected to acidic microwave-assisted digestion in a nitric-sulfuric acid mixture. Chemical hydride generation with 0.5% NaBH4 after the prereduction of As(V) and Sb(V) with 0.3% L-cysteine in 0.01 mol l(-1) HCl (10 min contact time at 90±5°C) was used. Under the optimal hydride generation conditions and analytical system operation the detection limits (mg kg(-1)) were 0.5 (As) and 0.1 (Sb), whereas the precision was 0.4-7.1% for 10.2-46.2 mg kg(-1) As and 0.4-3.2% for 7.1-156 mg kg(-1) Sb. Analysis of two polyethylene CRMs revealed recoveries of 101±2% As and 100±1% Sb.

  18. Simultaneous determination of atenolol and amiloride in pharmaceutical preparations by capillary zone electrophoresis with capacitively coupled contactless conductivity detection.

    PubMed

    Al Azzam, Khaldun M; Saad, Bahruddin; Aboul-Enein, Hassan Y

    2010-09-01

    Capillary zone electrophoresis coupled with a capacitively coupled contactless conductivity detector (CE-C(4)D) has been employed for the determination of atenolol and amiloride in pharmaceutical formulations. Acetic acid (150 mm) was used as background electrolyte. The influence of several factors (detector excitation voltage and frequency, buffer concentration, applied voltage, capillary temperature and injection time) was studied. Non-UV-absorbing L-valine was used as internal standard; the analytes were all separated in less than 7 min. The separation was carried out in normal polarity mode at 28 degrees C, 25 kV and using hydrodynamic injection (25 s). The separation was effected in an uncoated fused-silica capillary (75 microm, i.d. x 52 cm). The CE-C(4)D method was validated with respect to linearity, limit of detection and quantification, accuracy, precision and selectivity. Calibration curves were linear over the range 5-250 microg/mL for the studied analytes. The relative standard deviations of intra- and inter-day migration times and corrected peak areas were less than 6.0%. The method showed good precision and accuracy and was successfully applied to the simultaneous determination of atenolol and amiloride in different pharmaceutical tablet formulations.

  19. New observations and new models of spin-orbit coupling in binary asteroids

    NASA Astrophysics Data System (ADS)

    Margot, Jean-Luc; Naidu, Shantanu

    2015-08-01

    The YORP-induced rotational fission hypothesis is the leading candidate for explaining the formation of binaries, triples, and pairs among small (<20 km) asteroids (e.g., Margot et al, Asteroids IV, subm., 2015). Various evolutionary paths following rotational fission have been suggested, but many important questions remain about the evolutionary mechanisms and timescales. We test hypotheses about the evolution of binary asteroids by obtaining precise descriptions of the orbits and components of binary systems with radar and by examining the system dynamics with detailed numerical simulations. Predictions for component spin states and orbital precession rates can then be compared to observables in our data sets or in other data sets to elucidate the states of various systems and their likely evolutionary paths.Accurate simulations require knowledge of the masses, shapes, and spin states of individual binary components. Because radar observations can provide exquisite data sets spanning days with spatial resolutions at the decameter level, we can invert for the component shapes and measure spin states. We can also solve for the mutual orbit by fitting the observed separations between components. In addition, the superb (10e-7--10e-8) fractional uncertainties in range allow us to measure the reflex motions directly, allowing masses of individual components to be determined.We use recently published observations of the binary 2000 DP107 (Naidu et al. AJ, subm., 2015) and that of other systems to simulate the dynamics of components in well-characterized binary systems (Naidu and Margot, AJ 149, 80, 2015). We model the coupled spin and orbital motions of two rigid, ellipsoidal bodies under the influence of their mutual gravitational potential. We use surface of section plots to map the possible spin configurations of the satellites. For asynchronous satellites, the analysis reveals large regions of phase space where the spin state of the satellite is chaotic. The

  20. Different modes of a capacitively coupled radio-frequency discharge in methane.

    PubMed

    Schweigert, I V

    2004-04-16

    The transition between different regimes of a capacitevely coupled radio-frequency gas discharge in methane is studied with a combined particle-in-cell Monte Carlo collision algorithm over a wide range of gas pressure P and discharge current j. The results of this study are compared with known experimental and numerical results and summarized on a P-j phase diagram, which constitutes the areas of existence of different discharge regimes.

  1. Different Modes of a Capacitively Coupled Radio-Frequency Discharge in Methane

    NASA Astrophysics Data System (ADS)

    Schweigert, I. V.

    2004-04-01

    The transition between different regimes of a capacitevely coupled radio-frequency gas discharge in methane is studied with a combined particle-in-cell Monte Carlo collision algorithm over a wide range of gas pressure P and discharge current j. The results of this study are compared with known experimental and numerical results and summarized on a P-j phase diagram, which constitutes the areas of existence of different discharge regimes.

  2. A Polarization Reconfigurable Aperture-Coupled Microstrip Antenna and Its Binary Array for MIMO

    NASA Astrophysics Data System (ADS)

    Zhong, Lei; Hong, Jin-Song; Zhou, Hong-Cheng

    2016-03-01

    In the paper, a singly fed circular patch antenna with polarization diversity is proposed, and its binary array for MIMO application is explored as well. The air substrate and aperture-coupled feed structure are adopted to increase bandwidth and simplify the bias circuit of PIN diodes. By controlling the states of four PIN diodes on the patch, the proposed antenna can produce linear polarization (LP), left- or right-hand circular polarization (LHCP or RHCP). For each polarization sense, the antenna exhibits wide impedance bandwidth, high gain and low cross-polarization. Two antennas are orthogonally placed to form a binary array for MIMO application, which has high isolation and low envelope correlation. The antenna and its array have advantages of simple biasing network, easy fabrication and adjustment, which can be widely applied in wireless communication systems.

  3. Application of capacitively coupled contactless conductivity as an external detector for zone electrophoresis in poly(dimethylsiloxane) chips.

    PubMed

    Koczka, Péter I; Bodoki, Ede; Gáspár, Attila

    2016-02-01

    In this work, lab-made PDMS microfluidic chips were matched to a capacitively coupled contactless conductivity detector (C(4) D) having external in-plane electrodes (eDAQ, Australia). The advantages of this type of C(4) D are the choice to reversibly place or remove the microchip onto/from the detector and to freely variate the position of the detection (separation length) on the microchip. The thickness of the bottom layer of the PDMS chip was optimized to achieve sensitive detection during the electrophoretic separation. PDMS chips with 100 μm bottom layer used with the C(4) D platform were tested by CZE of a mixture of seven anions and different types of real samples. Using split-flow pressure sample injection and effective length of 6.5 cm, the numbers of theoretical plates were in the range of 4000-6000 (63,000-93,000/m) and the LODs amounted to 3.66-14.7 μmol/L (0.13-2.26 μg/mL) for the studied anions. PMID:26531885

  4. Influence of dielectric materials on uniformity of large-area capacitively coupled plasmas for N2/Ar discharges

    NASA Astrophysics Data System (ADS)

    Liang, Ying-Shuang; Zhang, Yu-Ru; Wang, You-Nian

    2016-10-01

    The effect of the dielectric ring on the plasma radial uniformity is numerically investigated in the practical 450-mm capacitively coupled plasma reactor by a two-dimensional self-consistent fluid model. The simulations were performed for N2/Ar discharges at the pressure of 300 Pa, and the frequency of 13.56 MHz. In the practical plasma treatment process, the wafer is always surrounded by a dielectric ring, which is less studied. In this paper, the plasma characteristics are systematically investigated by changing the properties of the dielectric ring, i.e., the relative permittivity, the thickness and the length. The results indicate that the plasma parameters strongly depend on the properties of the dielectric ring. As the ratio of the thickness to the relative permittivity of the dielectric ring increases, the electric field at the wafer edge becomes weaker due to the stronger surface charging effect. This gives rise to the lower ion density, flux and N atom density at the wafer edge. Thus the homogeneous plasma density is obtained by selecting optimal dielectric ring relative permittivity and thickness. In addition, we also find that the length of the dielectric ring should be as short as possible to avoid the discontinuity of the dielectric materials, and thus obtain the large area uniform plasma. Project supported by the National Natural Science Foundation of China (Grant Nos. 11335004 and 11405019) and the Important National Science and Technology Specific Project of China (Grant No. 2011ZX02403-001).

  5. Characteristics of dual-frequency capacitively coupled SF6/O2 plasma and plasma texturing of multi-crystalline silicon

    NASA Astrophysics Data System (ADS)

    Xu, Dong-Sheng; Zou, Shuai; Xin, Yu; Su, Xiao-Dong; Wang, Xu-Sheng

    2014-06-01

    Due to it being environmentally friendly, much attention has been paid to the dry plasma texturing technique serving as an alternative candidate for multicrystalline silicon (mc-Si) surface texturing. In this paper, capacitively coupled plasma (CCP) driven by a dual frequency (DF) of 40.68 MHz and 13.56 MHz is first used for plasma texturing of mc-Si with SF6/O2 gas mixture. Using a hairpin resonant probe and optical emission techniques, DF-CCP characteristics and their influence on mc-silicon surface plasma texturing are investigated at different flow rate ratios, pressures, and radio-frequency (RF) input powers. Experimental results show that suitable plasma texturing of mc-silicon occurs only in a narrow range of plasma parameters, where electron density ne must be larger than 6.3 × 109 cm-3 and the spectral intensity ratio of the F atom to that of the O atom ([F]/[O]) in the plasma must be between 0.8 and 0.3. Out of this range, no cone-like structure is formed on the mc-silicon surface. In our experiments, the lowest reflectance of about 7.3% for mc-silicon surface texturing is obtained at an [F]/[O] of 0.5 and ne of 6.9 × 109 cm-3.

  6. Reversal of the asymmetry in a cylindrical coaxial capacitively coupled Ar/Cl2 plasma

    SciTech Connect

    Upadhyay, Janardan; Im, Do; Popović, Svetozar; Vušković, Leposava; Valente-Feliciano, Anne -Marie; Phillips, Larry

    2015-10-08

    The reduction of the asymmetry in the plasma sheath voltages of a cylindrical coaxial capacitively coupled plasma is crucial for efficient surface modification of the inner surfaces of concave three-dimensional structures, including superconducting radio frequency cavities. One critical asymmetry effect is the negative dc self-bias, formed across the inner electrode plasma sheath due to its lower surface area compared to the outer electrode. The effect on the self-bias potential with the surface enhancement by geometric modification on the inner electrode structure is studied. The shapes of the inner electrodes are chosen as cylindrical tube, large and small pitch bellows, and disc-loaded corrugated structure (DLCS). The dc self-bias measurements for all these shapes were taken at different process parameters in Ar/Cl2 discharge. Lastly, the reversal of the negative dc self-bias potential to become positive for a DLCS inner electrode was observed and the best etch rate is achieved due to the reduction in plasma asymmetry.

  7. The electric field in capacitively coupled RF discharges: a smooth step model that includes thermal and dynamic effects

    NASA Astrophysics Data System (ADS)

    Brinkmann, Ralf Peter

    2015-12-01

    The electric field in radio-frequency driven capacitively coupled plasmas (RF-CCP) is studied, taking thermal (finite electron temperature) and dynamic (finite electron mass) effects into account. Two dimensionless numbers are introduced, the ratios ε ={λ\\text{D}}/l of the electron Debye length {λ\\text{D}} to the minimum plasma gradient length l (typically the sheath thickness) and η ={ω\\text{RF}}/{ω\\text{pe}} of the RF frequency {ω\\text{RF}} to the electron plasma frequency {ω\\text{pe}} . Assuming both numbers small but finite, an asymptotic expansion of an electron fluid model is carried out up to quadratic order inclusively. An expression for the electric field is obtained which yields (i) the space charge field in the sheath, (ii) the generalized Ohmic and ambipolar field in the plasma, and (iii) a smooth interpolation for the transition in between. The new expression is a direct generalization of the Advanced Algebraic Approximation (AAA) proposed by the same author (2009 J. Phys. D: Appl. Phys. 42 194009), which can be recovered for η \\to 0 , and of the established Step Model (SM) by Godyak (1976 Sov. J. Plasma Phys. 2 78), which corresponds to the simultaneous limits η \\to 0 , ε \\to 0 . A comparison of the hereby proposed Smooth Step Model (SSM) with a numerical solution of the full dynamic problem proves very satisfactory.

  8. 2D fluid model analysis for the effect of 3D gas flow on a capacitively coupled plasma deposition reactor

    NASA Astrophysics Data System (ADS)

    Kim, Ho Jun; Lee, Hae June

    2016-06-01

    The wide applicability of capacitively coupled plasma (CCP) deposition has increased the interest in developing comprehensive numerical models, but CCP imposes a tremendous computational cost when conducting a transient analysis in a three-dimensional (3D) model which reflects the real geometry of reactors. In particular, the detailed flow features of reactive gases induced by 3D geometric effects need to be considered for the precise calculation of radical distribution of reactive species. Thus, an alternative inclusive method for the numerical simulation of CCP deposition is proposed to simulate a two-dimensional (2D) CCP model based on the 3D gas flow results by simulating flow, temperature, and species fields in a 3D space at first without calculating the plasma chemistry. A numerical study of a cylindrical showerhead-electrode CCP reactor was conducted for particular cases of SiH4/NH3/N2/He gas mixture to deposit a hydrogenated silicon nitride (SiN x H y ) film. The proposed methodology produces numerical results for a 300 mm wafer deposition reactor which agree very well with the deposition rate profile measured experimentally along the wafer radius.

  9. Mass spectrometry of positive ions in capacitively coupled low pressure RF discharges in oxygen with water impurities

    NASA Astrophysics Data System (ADS)

    Stefanović, Ilija; Stojanović, Vladimir; Boulmer-Leborgne, Chantal; Lecas, Thomas; Kovacevic, Eva; Berndt, Johannes

    2016-07-01

    A capacitively coupled RF oxygen discharge is studied by means of mass spectroscopy. Mass spectra of neutral and positive species are measured in the mid plane between the electrodes at different distances between plasma and mass-spectrometer orifice. In the case of positive ions, as expected, the largest flux originates from \\text{O}2+ . However, a significant number of impurities are detected, especially for low input powers and larger distances. The most abundant positive ions (besides \\text{O}2+ ) are \\text{N}{{\\text{O}}+}, \\text{NO}2+ , {{\\text{H}}+}≤ft({{\\text{H}}2}\\text{O}\\right) , and {{\\text{H}}+}{{≤ft({{\\text{H}}2}\\text{O}\\right)}2} . In particular, for the case of hydrated hydronium ions {{\\text{H}}+}{{≤ft({{\\text{H}}2}\\text{O}\\right)}n} (n  =  1, 2) a surprisingly large flux (for low pressure plasma conditions) is detected. Another interesting fact concerns the {{\\text{H}}2}{{\\text{O}}+} ions. Despite the relatively high ammount of water impurities {{\\text{H}}2}{{\\text{O}}+} ions are present only in traces. The reaction mechanisms leading to the production of the observed ions, especially the hydrated hydronium ions are discussed.

  10. Experimental and numerical investigations of electron density in low-pressure dual-frequency capacitively coupled oxygen discharges

    SciTech Connect

    Liu, Jia; Wen, De-Qi; Liu, Yong-Xin; Gao, Fei; Lu, Wen-Qi; Wang, You-Nian

    2013-11-15

    The electron density is measured in low-pressure dual-frequency (2/60 MHz) capacitively coupled oxygen discharges by utilizing a floating hairpin probe. The dependence of electron density at the discharge center on the high frequency (HF) power, low frequency (LF) power, and gas pressure are investigated in detail. A (1D) particle-in-cell/Monte Carlo method is developed to calculate the time-averaged electron density at the discharge center and the simulation results are compared with the experimental ones, and general agreements are achieved. With increasing HF power, the electron density linearly increases. The electron density exhibits different changes with the LF power at different HF powers. At low HF powers (e.g., 30 W in our experiment), the electron density increases with increasing LF power while the electron density decreases with increasing LF power at relatively high HF powers (e.g., 120 W in our experiment). With increasing gas pressure the electron density first increases rapidly to reach a maximum value and then decreases slowly due to the combined effect of the production process by the ionization and the loss processes including the surface and volume losses.

  11. Mercury determination in non- and biodegradable materials by cold vapor capacitively coupled plasma microtorch atomic emission spectrometry.

    PubMed

    Frentiu, Tiberiu; Mihaltan, Alin I; Ponta, Michaela; Darvasi, Eugen; Frentiu, Maria; Cordos, Emil

    2011-10-15

    A new analytical system consisting of a low power capacitively coupled plasma microtorch (20 W, 13.56 MHz, 150 ml min(-1) Ar) and a microspectrometer was investigated for the Hg determination in non- and biodegradable materials by cold-vapor generation, using SnCl(2) reductant, and atomic emission spectrometry. The investigated miniaturized system was used for Hg determination in recyclable plastics from electronic equipments and biodegradable materials (shopping bags of 98% biodegradable polyethylene and corn starch) with the advantages of easy operation and low analysis costs. Samples were mineralized in HNO(3)-H(2)SO(4) mixture in a high-pressure microwave system. The detection limits of 0.05 ng ml(-1) or 0.08 μg g(-1) in solid sample were compared with those reported for other analytical systems. The method precision was 1.5-9.4% for Hg levels of 1.37-13.9 mg kg(-1), while recovery in two polyethylene certified reference materials in the range 98.7 ± 4.5% (95% confidence level).

  12. Application of capacitively coupled contactless conductivity as an external detector for zone electrophoresis in poly(dimethylsiloxane) chips.

    PubMed

    Koczka, Péter I; Bodoki, Ede; Gáspár, Attila

    2016-02-01

    In this work, lab-made PDMS microfluidic chips were matched to a capacitively coupled contactless conductivity detector (C(4) D) having external in-plane electrodes (eDAQ, Australia). The advantages of this type of C(4) D are the choice to reversibly place or remove the microchip onto/from the detector and to freely variate the position of the detection (separation length) on the microchip. The thickness of the bottom layer of the PDMS chip was optimized to achieve sensitive detection during the electrophoretic separation. PDMS chips with 100 μm bottom layer used with the C(4) D platform were tested by CZE of a mixture of seven anions and different types of real samples. Using split-flow pressure sample injection and effective length of 6.5 cm, the numbers of theoretical plates were in the range of 4000-6000 (63,000-93,000/m) and the LODs amounted to 3.66-14.7 μmol/L (0.13-2.26 μg/mL) for the studied anions.

  13. Experimental and theoretical study of RF capacitively coupled plasma in Ar-CF4-CF3I mixtures

    NASA Astrophysics Data System (ADS)

    Proshina, O. V.; Rakhimova, T. V.; Lopaev, D. V.; Šamara, V.; Baklanov, M. R.; de Marneffe, J.-F.

    2015-10-01

    Radio frequency capacitively coupled plasma (RF CCP) sustained at RF frequencies of 27 MHz in an Ar-CF4-CF3I gas mixture is studied experimentally and theoretically. The RF CCP in Ar-CF4-CF3I is simulated by using a 1D hybrid particle-in-cell-fluid numerical model. We pay special attention to the changes in plasma structure and fluxes to the electrode, negative ion and neutral radical production with admixture of CF3I in Ar-CF4 plasma. With CF3I admixture the plasma becomes strongly electronegative as a result of the high electron attachment rate to the CF3I molecule. The atomic fluorine density becomes extremely low with addition of CF3I molecules due to the large volume loss in the reaction CF3I + F  →  CF3 + IF. Optical emission spectrometry data on CF2 emission at the wavelength of 250 nm indicate the essential sources of CF2 in CF3I-containing plasma in the studied conditions, although direct dissociation channels for the CF3I molecule with CF2 production have not been studied. Evaluation of CF2 density in Ar-CF4-CF3I plasma was first carried out on the basis of the actinometry technique and numerical simulation. The possible mechanism of ultra-low-k film damage in the studied conditions is also discussed.

  14. Investigation of ion energy and angular distributions at the wafer edge in rf capacitively coupled reactors using CFD-ACE+

    NASA Astrophysics Data System (ADS)

    Bhoj, Ananth; Roy, Abhra; Jain, Kunal; Xiong, Zhongmin

    2015-09-01

    Dual frequency capacitively coupled reactors are now commonly used in microelectronics fabrication. The extent of possible independent control of ion fluxes and ion energy and angular distribution (IEADs) by varying HF and LF signals is currently a topic of great interest. In this study, we report on investigations of IEADs in single and dual frequency CCPs, including the wafer edge refinement using CFD-ACE+. The current algorithms in CFD-ACE+ allow the determination of total power at the electrode or in the discharge. To account for the presence of two or more rf sources connected to a powered electrode, the existing numerical algorithms for power targeting were enhanced to track current at the electrode as a function of time, vary voltage and determine power as a function of frequency. The Monte Carlo transport module for heavy species in CFD-ACE+ was recently enhanced to compute IEADs in rf discharges. Results for the effect of varying power and pressure on IEADs were compared to semi-analytical models and data reported in Gahan et al.. The validated model was applied to investigate the effect of details of HF and LF signals on IEADs in Argon discharges.

  15. Generation of optical and matter-wave solitons in binary systems with a periodically modulated coupling

    SciTech Connect

    Niederberger, Armand; Malomed, Boris A.; Lewenstein, Maciej

    2010-10-15

    We present a systematic study of the generation of the array of optical or matter-wave kinks (dark solitons) in the ground state (GS) of binary systems. We consider quasi-one-dimensional systems described by a pair of nonlinear Schroedinger (NLSE's) or Gross-Pitaevskii equations (GPE's), which are coupled by the linear mixing, with local strength {Omega}, and by nonlinear interactions. We assume the self-repulsive nonlinearity in both components, and include the effects of a harmonic trapping potential, while the nonlinear interaction between the components may be both repulsive and attractive. The model may be realized in terms of periodically modulated slab waveguides in nonlinear optics and also in Bose-Einstein condensates. Depending on the sign and strengths of the linear and nonlinear couplings between the components, the ground states in such binary systems may be symmetric, antisymmetric, or asymmetric. In this work, we introduce a periodic spatial modulation of the linear coupling, making {Omega} an odd or even function of the coordinate (x). The sign flips of {Omega}(x) strongly modify the structure of the GS in the binary system, as the relative sign of its components tends to lock to the local sign of {Omega}. Using a systematic numerical analysis and an analytic approximation, we demonstrate that the GS of the trapped system contains one or several kinks (dark solitons) in one component, while the other component does not change its sign. The final results are presented in the form of maps showing the number of kinks in the GS as a function of the system's parameters, with the odd (even) modulation function giving rise to the odd (even) number of the kinks. The modulation of {Omega}(x) also produces a strong effect on the transition between states with nearly equal and strongly unequal amplitudes of the two components.

  16. Coupled Spin and Orbital Dynamics of Binary Near-Earth Asteroids 2000 DP107 and 1991 VH

    NASA Astrophysics Data System (ADS)

    Naidu, Shantanu; Margot, J.

    2013-10-01

    Binaries form a significant fraction 15%) of the near-Earth asteroid (NEA) population. Various models suggest that they are evolving and that some of them might be in an intermediate stage towards the formation of binary pairs, contact binary NEAs, or triple NEAs. Binary NEAs are thought to evolve under the influence of gravitational and radiative forces such as YORP and binary YORP (e.g., Cuk and Burns, 2005). A wide variety of end-states may arise depending on the relative magnitudes of the forces, which are dictated by the component shapes, spins, and mutual orbit of the binary (e.g., Jacobson & Scheeres 2011, Fang & Margot 2012). Because the spins and mutual orbits of binary NEAs are tightly coupled to each other, understanding the spin-orbit interaction is key to modeling binary NEA evolution. This interaction can be studied using asteroid shape models (e.g., Scheeres et al. 2006, Fahnestock and Scheeres, 2006). We will present numerical simulations describing the spin-orbit states of two binary NEAs, 2000 DP107 and 1991 VH, as well as the consequences for the evolution of binary NEAs. Naidu et al. (2011) presented the radar-derived component shape models, masses, densities, spin states, and the mutual orbit of binary near-Earth asteroid 2000 DP107. The smaller component spins synchronously and may exhibit small amplitude (< 5 degree) librations. The mutual orbit pole and primary spin pole fits to the radar data suggest that they are inclined with respect to each other. Such an inclined orbit would precess due to the oblateness of the primary component. For 1991 VH, Naidu et al. (2012) were unable to fit a unique spin period to the elongated secondary using radar images and suggested that it might be in a chaotic spin state on the basis of theoretical considerations and numerical simulations. We will present improved simulations that include spin-orbit coupling.

  17. Modeling of the nanoparticle coagulation in pulsed radio-frequency capacitively coupled C2H2 discharges

    NASA Astrophysics Data System (ADS)

    Liu, Xiang-Mei; Li, Qi-Nan; Li, Rui

    2015-07-01

    The role of pulse parameters on nanoparticle property is investigated self-consistently based on a couple of fluid model and aerosol dynamics model in a capacitively coupled parallel-plate acetylene (C2H2) discharge. In this model, the mass continuity equation, momentum balance equation, and energy balance equation for neutral gas are taken into account. Thus, the thermophoretic force arises when a gas temperature gradient exists. The typical results of this model are positive and negative ion densities, electron impact collisions rates, nanoparticle density, and charge distributions. The simulation is performed for duty ratio 0.4/0.7/1.0, as well as pulse modulation frequency from 40 kHz to 2.7 MHz for pure C2H2 discharges at a pressure of 500 mTorr. We find that the pulse parameters, especially the duty ratio, have a great affect on the dissociative attachment coefficient and the negative density. More importantly, by decreasing the duty ratio, nanoparticles start to diffuse to the wall. Under the action of gas flow, nanoparticle density peak is created in front of the pulse electrode, where the gas temperature is smaller. Project supported by the Natural Science Foundation of Heilongjiang Province, China (Grant Nos. A2015011 and A2015010), the Postdoctoral Scientific Research Developmental Fund of Heilongjiang Province, China (Grant No. LBH-Q14159), the National Natural Science Foundation of China (Grant No. 11404180), and the Program for Young Teachers Scientific Research in Qiqihar University, China (Grant No. 2014k-Z11).

  18. Binary data corruption due to a Brownian agent. II. Two dimensions, competing agents, and generalized couplings.

    PubMed

    Triampo, W; Newman, T J

    1999-08-01

    This work is a continuation of our previous investigation of binary data corruption due to a Brownian agent [Phys. Rev. E 59, 5172 (1999)]. We extend our study in three main directions which allow us to make closer contact with real bistable systems. These are (i) a detailed analysis of two dimensions, (ii) the case of competing agents, and (iii) the cases of asymmetric and quenched random couplings. Most of our results are obtained by extending our original phenomenological model, and are supported by extensive numerical simulations.

  19. Phase-field modeling of binary alloy solidification with coupled heat and solute diffusion.

    PubMed

    Ramirez, J C; Beckermann, C; Karma, A; Diepers, H-J

    2004-05-01

    A phase-field model is developed for simulating quantitatively microstructural pattern formation in solidification of dilute binary alloys with coupled heat and solute diffusion. The model reduces to the sharp-interface equations in a computationally tractable thin-interface limit where (i). the width of the diffuse interface is about one order of magnitude smaller than the radius of curvature of the interface but much larger than the real microscopic width of a solid-liquid interface, and (ii). kinetic effects are negligible. A recently derived antitrapping current [Phys. Rev. Lett. 87, 115701 (2001)

  20. Measuring the composition-curvature coupling in binary lipid membranes by computer simulations

    SciTech Connect

    Barragán Vidal, I. A. Müller, M.; Rosetti, C. M.; Pastorino, C.

    2014-11-21

    The coupling between local composition fluctuations in binary lipid membranes and curvature affects the lateral membrane structure. We propose an efficient method to compute the composition-curvature coupling in molecular simulations and apply it to two coarse-grained membrane models—a minimal, implicit-solvent model and the MARTINI model. Both the weak-curvature behavior that is typical for thermal fluctuations of planar bilayer membranes as well as the strong-curvature regime corresponding to narrow cylindrical membrane tubes are studied by molecular dynamics simulation. The simulation results are analyzed by using a phenomenological model of the thermodynamics of curved, mixed bilayer membranes that accounts for the change of the monolayer area upon bending. Additionally the role of thermodynamic characteristics such as the incompatibility between the two lipid species and asymmetry of composition are investigated.

  1. Capacitively-Coupled Resistivity measurements to determine frequency dependent electrical parameters in periglacial environment - theoretical considerations and first field tests.

    NASA Astrophysics Data System (ADS)

    Przyklenk, A.; Hördt, A.; Radić, T.

    2016-05-01

    Capacitively-Coupled Resistivity (CCR) is conventionally used to emulate DC resistivity measurements and may provide important information about the ice content of material in periglacial areas. The application of CCR theoretically enables the determination of both electrical parameters, i.e. the resistivity and the electrical permittivity, by analyzing magnitude and phase shift spectra. The electrical permittivity may dominate the impedance, especially in periglacial areas or regions of hydrogeological interest. However, previous theoretical work suggested that the phase shift may strongly depend on electrode height above ground, implying that electrode height must be known with great accuracy to determine electrical permittivity. Here, we demonstrate with laboratory test measurements, theoretical modelling and by analysing the Jacobian matrix of the inversion, that the sensitivity towards electrode height is drastically reduced if the electrical permittivity is frequency dependent in a way that is typical for ice. For the fist time, we used a novel broadband CCR device "Chameleon" for a field test located in one of the ridge galleries beneath the crest of Mount Zugspitze. A permanently ice covered bottom of a tunnel was examined. For the inversion of the measured spectra, the frequency dependance of the electrical parameters was parameterized in 3 different ways. A Debye Model for pure ices, a Cole-Cole Model for pure ices and a dual Cole-Cole Model including interfacial water additionally. The frequency-dependent resistivity and permittivity spectra obtained from the inversion, including low and high frequency limits, agree reasonably well with laboratory and field measurements reported in the literature.

  2. Electron heating enhancement due to plasma series resonance in a capacitively coupled RF discharge: Electrical modeling and comparison to experimental measurements

    NASA Astrophysics Data System (ADS)

    Cao, Minglu; Lu, Yijia; Cheng, Jia; Ji, Linhong

    2016-09-01

    The electron heating enhancement due to the self-excitation of the plasma series resonance in capacitively coupled plasmas is revisited by a combination of an equivalent circuit model and experiments. To improve the model accuracy, measured voltage waveforms at the powered electrode are used instead of prescribing a sinusoidal voltage supply in series with a bias capacitance. The results calculated from the electrical model are consistent with the experimental measurements performed by a Langmuir probe with verification of a microwave interferometer, at pressures of 0.2 and 0.3 Torr. High harmonics occurring in the discharge currents agree with observations in previous research. The nonlinear plasma series resonance effect is found to have a notable contribution to both ohmic and stochastic heating evaluated by the electron heating efficiencies.

  3. Pulsed two-frequency capacitively coupled plasma simulation with H_2/N2 mixtures for the etching of low-k materials

    NASA Astrophysics Data System (ADS)

    Shon, C. H.; Makabe, T.

    2002-10-01

    As the critical dimension of integrated circuit is scaled down, the resistance-capacitance (RC) delay of signals through interconnection materials becomes important. As a solution, the new materials like Cu and low-k dielectric polymers have been used to reduce the signal delay in interconnect. As a result, low-k materials etching becomes a big issue in the plasma etching process. In this research, we present the simulation results of a pulsed two-frequency capacitively coupled plasma (2f-CCP)[1,2] based on relaxation continuum (RCT) model[3,4] in H_2/N2 mixtures. The electrons, ions of each gas and NHx radicals are followed in the model. The characteristics of a pulsed plasma are investigated. In addition, the flux of ions and radicals toward the biased substrate which has great importance in etching process is also discussed. sep = -1mm [[1

  4. Experimental demonstration of sharp Fano resonance within binary gold nanodisk array through lattice coupling effects.

    PubMed

    Zhao, Wenyu; Jiang, Yongyuan

    2015-01-01

    Fano resonance originating from the interaction of anti-phased and in-phased lattice collective resonances supported by a binary gold nanodisk array is investigated both numerically and experimentally. As the magnitude of particle radii in the two arrays approaches gradually, the Q factor of such resonance increases while the spectral contrast reduces. In the experiment, a high spectral contrast of 0.7 and a large Q factor of 14 could be achieved at the same time due to the excitation of the pure dipole resonance of each particle resulting from the weak near-field coupling. Optimal calculation gives rise to a higher Q factor of up to 85 and a corresponding spectral contrast of 0.86, which is very promising in refractive sensors. The sensitivity and the figure of merit are 337  nm/RIU and 116, respectively.

  5. Cation effects in the oxidative coupling of methane on silica-supported binary alkali and alkaline earths

    SciTech Connect

    Voyatzis, R.; Moffat, J.B. )

    1993-07-01

    The oxidative coupling of methane has been investigated with a series of silica-supported binary oxide catalysts containing alkali or alkaline earths or combinations of the former and latter. The conversion of methane and the stability of the silica-supported binary alkali metal oxides were found to increase with decreasing cation mobility, while the selectivities and conversions observed with the binary alkaline earths increase with cation size. The selectivities and conversions of binary alkali/alkaline earths appear to depend upon the size of the alkali and alkaline earth cations, respectively. With small quantities of TCM (CCl[sub 4]) added continuously to the feedstream, catalysts containing small alkali and large alkaline earth cations produced the largest selectivities and conversions. 23 refs., 14 figs., 2 tabs.

  6. Effect of driving voltages in dual capacitively coupled radio frequency plasma: A study by nonlinear global model

    SciTech Connect

    Bora, B.

    2015-10-15

    On the basis of nonlinear global model, a dual frequency capacitively coupled radio frequency plasma driven by 13.56 MHz and 27.12 MHz has been studied to investigate the influences of driving voltages on the generation of dc self-bias and plasma heating. Fluid equations for the ions inside the plasma sheath have been considered to determine the voltage-charge relations of the plasma sheath. Geometrically symmetric as well as asymmetric cases with finite geometrical asymmetry of 1.2 (ratio of electrodes area) have been considered to make the study more reasonable to experiment. The electrical asymmetry effect (EAE) and finite geometrical asymmetry is found to work differently in controlling the dc self-bias. The amount of EAE has been primarily controlled by the phase angle between the two consecutive harmonics waveforms. The incorporation of the finite geometrical asymmetry in the calculations shift the dc self-bias towards negative polarity direction while increasing the amount of EAE is found to increase the dc self-bias in either direction. For phase angle between the two waveforms ϕ = 0 and ϕ = π/2, the amount of EAE increases significantly with increasing the low frequency voltage, whereas no such increase in the amount of EAE is found with increasing high frequency voltage. In contrast to the geometrically symmetric case, where the variation of the dc self-bias with driving voltages for phase angle ϕ = 0 and π/2 are just opposite in polarity, the variation for the geometrically asymmetric case is different for ϕ = 0 and π/2. In asymmetric case, for ϕ = 0, the dc self-bias increases towards the negative direction with increasing both the low and high frequency voltages, but for the ϕ = π/2, the dc-self bias is increased towards positive direction with increasing low frequency voltage while dc self-bias increases towards negative direction with increasing high frequency voltage.

  7. Thermal conductivity of highly asymmetric binary mixtures: how important are heat/mass coupling effects?

    PubMed

    Armstrong, Jeff; Bresme, Fernando

    2014-06-28

    The coupling of mass and heat fluxes is responsible for the Soret effect in fluid mixtures containing particles of dissimilar mass and/or size. We investigate using equilibrium and non-equilibrium molecular dynamics simulations the relevance of these coupling effects in determining the thermal transport in fluids consisting of binary mixtures where the individual components feature significant mass, 1 : 8, or size, 1 : 3, asymmetries. We quantify the thermal transport by using both boundary driven molecular dynamics simulations (NEMD) and the equilibrium Green-Kubo (GK) approach and investigate the impact of different heat flux definitions, relevant in kinetic theory and experiments, in the quantification of the thermal conductivity. We find that the thermal conductivities obtained from the different definitions agree within numerical accuracy, suggesting that the Soret coefficient does not lead to significant changes in the thermal conduction, even for the large asymmetries considered here, which lead to significant Soret coefficients (∼10(-2) K(-1)). The asymmetry in size and mass introduces large differences in the specific enthalpy of the individual components that must be carefully considered to compute accurate thermal conductivities using the GK approach. Neglecting the enthalpic contributions, results in large overestimations of the thermal conductivity, typically between 20% and 50%. Further, we quantify the time dependent behavior of the internal energy and mass flux correlation functions and propose a microscopic mechanism for the heat transport in these asymmetric mixtures.

  8. Magnetic dipolar coupling and collective effects for binary information codification in cost-effective logic devices

    NASA Astrophysics Data System (ADS)

    Chiolerio, Alessandro; Allia, Paolo; Graziano, Mariagrazia

    2012-09-01

    Physical limitations foreshadow the eventual end to traditional Complementary Metal Oxide Semiconductor (CMOS) scaling. Therefore, interest has turned to various materials and technologies aimed to succeed to traditional CMOS. Magnetic Quantum dot Cellular Automata (MQCA) are one of these technologies. Working MQCA arrays require very complex techniques and an excellent control on the geometry of the nanomagnets and on the quality of the magnetic thin film, thus limiting the possibility for MQCA of representing a definite solution to cost-effective, high density and low power consumption device demand. Counter-intuitively, moving towards bigger sizes and lighter technologies it is still possible to develop multi-state logic devices, as we demonstrated, whose main advantage is cost-effectiveness. Applications may be seen in low cost logic devices where integration and computational power are not the main issue, eventually using flexible substrates and taking advantage of the intrinsic mechanical toughness of systems where long range interactions do not need wirings. We realized cobalt micrometric MQCA arrays by means of Electron Beam Lithography, exploiting cost-effective processes such as lift-off and RF sputtering that usually are avoided due to their low control on array geometry and film roughness. Information relative to the magnetic configuration of MQCA elements including their eventual magnetic interactions was obtained from Magnetic Force Microscope (MFM) images, enhanced by means of a numerical procedure and presented in differential maps. We report the existence of bi-stable magnetic patterns, as detected by MFM while sampling the z-component of magnetic induction field, arising from dipolar inter-element magnetostatic coupling, able to store and propagate binary information. This is achieved despite the array quality and element magnetic state, which are low and multi-domain, respectively. We discuss in detail shape, inter-element spacing and dot profile

  9. Nonlinear dynamics of capacitive charging and desalination by porous electrodes.

    PubMed

    Biesheuvel, P M; Bazant, M Z

    2010-03-01

    The rapid and efficient exchange of ions between porous electrodes and aqueous solutions is important in many applications, such as electrical energy storage by supercapacitors, water desalination and purification by capacitive deionization, and capacitive extraction of renewable energy from a salinity difference. Here, we present a unified mean-field theory for capacitive charging and desalination by ideally polarizable porous electrodes (without Faradaic reactions or specific adsorption of ions) valid in the limit of thin double layers (compared to typical pore dimensions). We illustrate the theory for the case of a dilute, symmetric, binary electrolyte using the Gouy-Chapman-Stern (GCS) model of the double layer, for which simple formulae are available for salt adsorption and capacitive charging of the diffuse part of the double layer. We solve the full GCS mean-field theory numerically for realistic parameters in capacitive deionization, and we derive reduced models for two limiting regimes with different time scales: (i) in the "supercapacitor regime" of small voltages and/or early times, the porous electrode acts like a transmission line, governed by a linear diffusion equation for the electrostatic potential, scaled to the RC time of a single pore, and (ii) in the "desalination regime" of large voltages and long times, the porous electrode slowly absorbs counterions, governed by coupled, nonlinear diffusion equations for the pore-averaged potential and salt concentration.

  10. Difference in chemical reactions in bulk plasma and sheath regions during surface modification of graphene oxide film using capacitively coupled NH{sub 3} plasma

    SciTech Connect

    Lee, Sung-Youp; Kim, Chan; Kim, Hong Tak

    2015-09-14

    Reduced graphene oxide (r-GO) films were obtained from capacitively coupled NH{sub 3} plasma treatment of spin-coated graphene oxide (GO) films at room temperature. Variations were evaluated according to the two plasma treatment regions: the bulk plasma region (R{sub bulk}) and the sheath region (R{sub sheath}). Reduction and nitridation of the GO films began as soon as the NH{sub 3} plasma was exposed to both regions. However, with the increase in treatment time, the reduction and nitridation reactions differed in each region. In the R{sub bulk}, NH{sub 3} plasma ions reacted chemically with oxygen functional groups on the GO films, which was highly effective for reduction and nitridation. While in the R{sub sheath}, physical reactions by ion bombardment were dominant because plasma ions were accelerated by the strong electrical field. The accelerated plasma ions reacted not only with the oxygen functional groups but also with the broken carbon chains, which caused the removal of the GO films by the formation of hydrocarbon gas species. These results showed that reduction and nitridation in the R{sub bulk} using capacitively coupled NH{sub 3} plasma were very effective for modifying the properties of r-GO films for application as transparent conductive films.

  11. Kibble-Zurek dynamics in an array of coupled binary Bose condensates

    NASA Astrophysics Data System (ADS)

    Xu, Jun; Wu, Shuyuan; Qin, Xizhou; Huang, Jiahao; Ke, Yongguan; Zhong, Honghua; Lee, Chaohong

    2016-03-01

    Universal dynamics of spontaneous symmetry breaking is central to understanding the universal behavior of spontaneous defect formation in various systems from the early universe, condensed-matter systems to ultracold atomic systems. We explore the universal real-time dynamics in an array of coupled binary atomic Bose-Einstein condensates in optical lattices, which undergo a spontaneous symmetry breaking from the symmetric Rabi oscillation to the broken-symmetry self-trapping. In addition to Goldstone modes, there exist gapped Higgs modes whose excitation gap vanishes at the critical point. In the slow passage through the critical point, we analytically find that the symmetry-breaking dynamics obeys the Kibble-Zurek mechanism. From the scalings of bifurcation delay and domain formation, we numerically extract two Kibble-Zurek exponents, b1=ν/(1+ν z) and b2=1/(1+ν z) , which give the static correlation-length critical exponent ν and the dynamic critical exponent z. Our approach provides an efficient way for the simultaneous determination of the critical exponents ν and z for a continuous phase transition.

  12. Investigation of Interdiffusion Behavior in the Mo-Zr Binary System via Diffusion Couple Studies

    SciTech Connect

    A. Paz y Puente; J. Dickson; D.D. Keiser, Jr.; Y.H. Sohn

    2014-03-01

    Zirconium has recently garnered attention for use as a diffusion barrier between U–Mo metallic nuclear fuels and Al alloy cladding. In order to gain a fundamental understanding of the diffusional interactions, the interdiffusion behavior in the binary Mo–Zr system was investigated via solid-to-solid diffusion couples annealed in the temperature range of 750 to 1050 degrees C. A combination of scanning electron microscopy, X-ray energy dispersive spectroscopy, and electron probe microanalysis were used to examine the microstructure and concentration profiles across the interdiffusion zone. A large __-Zr (cI2) solid solution layer and a thin (approximately 1–2 um) layer of Mo2Zr (cF24) developed in all couples. Parabolic growth constants and concentration dependent interdiffusion coefficients were calculated for the Mo2Zr and Zr solid solution phases, respectively. The pre-exponential factor and activation energy for growth of the Mo2Zr phase were determined to be approximately 6.5 × 10- 15 m2/s and 90 kJ/mol, respectively. The interdiffusion coefficient in ___-Zr solid solution decreased with an increase in Mo concentration. Both the pre-exponential factors (2 × 10- 8 m2/s at 2 at.% Mo to near 5 × 10- 8 m2/s at 9 at.% Mo) and activation energies (140 kJ/mol at 2 at.% Mo to approximately 155 kJ/mol at 9 at.% Mo) of interdiffusion coefficients were determined to increase with an increase in Mo concentration.

  13. A scanning microscopy technique based on capacitive coupling with a field-effect transistor integrated with the tip.

    PubMed

    Shin, Kumjae; Kang, Dae sil; Lee, Sang hoon; Moon, Wonkyu

    2015-12-01

    We propose a method for measuring the capacitance of a thin layer using a Tip-on-Gate of Field-Effect Transistor (ToGoFET) probe. A ToGoFET probe with a metal-oxide-semiconductor field-effect transistor (MOSFET) with an ion-implant channel was embedded at the end of a cantilever and a Pt tip was fabricated using micro-machining. The ToGoFET probe was used to detect an alternating electric field at the dielectric surface. A dielectric buried metal sample was prepared; a sinusoidal input signal was applied to the buried metal lines; and the ToGoFET probe detected the electric field at the tip via the dielectric. The AC signal detected by the ToGoFET probe was demodulated by a simple AC-to-DC converter. Experimentally, it was shown that an electric field could be measured at the surface of the dielectric layer above a buried metal line. This promising result shows that it is possible to measure the surface local capacitance.

  14. A scanning microscopy technique based on capacitive coupling with a field-effect transistor integrated with the tip.

    PubMed

    Shin, Kumjae; Kang, Dae sil; Lee, Sang hoon; Moon, Wonkyu

    2015-12-01

    We propose a method for measuring the capacitance of a thin layer using a Tip-on-Gate of Field-Effect Transistor (ToGoFET) probe. A ToGoFET probe with a metal-oxide-semiconductor field-effect transistor (MOSFET) with an ion-implant channel was embedded at the end of a cantilever and a Pt tip was fabricated using micro-machining. The ToGoFET probe was used to detect an alternating electric field at the dielectric surface. A dielectric buried metal sample was prepared; a sinusoidal input signal was applied to the buried metal lines; and the ToGoFET probe detected the electric field at the tip via the dielectric. The AC signal detected by the ToGoFET probe was demodulated by a simple AC-to-DC converter. Experimentally, it was shown that an electric field could be measured at the surface of the dielectric layer above a buried metal line. This promising result shows that it is possible to measure the surface local capacitance. PMID:26231315

  15. The discharge mode transition and O({sup 5}p{sub 1}) production mechanism of pulsed radio frequency capacitively coupled plasma

    SciTech Connect

    Liu, X. Y.; Hu, J. T.; Liu, J. H.; Xiong, Z. L.; Liu, D. W.; Lu, X. P.; Shi, J. J.

    2012-07-23

    The discharge mode transition from uniform plasma across the gas gap to the {alpha} mode happens at the rising phase of the pulsed radio frequency capacitively coupled plasma (PRF CCP). This transition is attributed to the fast increasing stochastic heating at the edge of sheath. In the second stage with the stable current and voltage amplitude, the consistency between experimental and numerical spatial-temporal 777 nm emission profile suggests that He* and He{sub 2}* dominate the production of O({sup 5}p{sub 1}) through dissociation and excitation of O{sub 2}. Finally, the sterilization efficiency of PRF CCP is found to be higher than that of plasma jet.

  16. Performance Enhancement of Capacitive-Coupling Dual-gate Ion-Sensitive Field-Effect Transistor in Ultra-Thin-Body

    PubMed Central

    Jang, Hyun-June; Cho, Won-Ju

    2014-01-01

    Recently, thin-film transistor based-ISFETs with the dual-gate (DG) structures have been proposed, in order to beat the Nernst response of the standard ISFET, utilizing diverse organic or inorganic materials. The immutable Nernst response can be dramatically transformed to an ultra-sensing margin, with the capacitive-coupling arisen from the DG structure. In order to advance this platform, we here embedded the ultra-thin body (UTB) into the DG ISFET. The UTB of 4.3 nm serves to not only increase its sensitivity, but also to strongly suppress the leakage components, leading to a better stability of the DG ISFET. In addition, we first provide a comprehensive analysis of the body thickness effects especially how the thick body can render the degradation in the device performance, such as sensitivity and stability. The UTB DG ISFET will allow the ISFET-based biosensor platform to continue enhancement into the next decade. PMID:24923751

  17. Hyperthermic therapy of deep seated tumors: comparison of the heating efficiencies of an annular array applicator and a capacitively coupled radiofrequency system.

    PubMed

    Egawa, S; Tsukiyama, I; Akine, Y; Kajiura, Y; Ogino, T; Yamashita, K

    1988-03-01

    Among 82 cases of deep seated tumors treated by hyperthermia with an annular array applicator (AA) and/or a capacitively coupled 8 mHz system (CCS) combined with radiation therapy, 13 cases were treated by both devices. The efficiencies of tumor heating were compared in terms of the time required to attain 42 degrees C, the duration of heating time and the thermal dose as determined by a biological iso-effect formula for equivalent minutes at 42.5 degrees C. Temperature profiles and percent of temperature levels greater than 42 degrees C were better in the cases treated by the AA, but higher thermal doses were obtained with the CCS because longer treatment times were tolerated with the CCS than with the AA. Methods are necessary to prevent excess elevation of body temperature in the case of the AA, and to reduce superficial pain where the applicators contact the skin in the case of the CCS.

  18. Comparison of atmospheric-pressure helium and argon plasmas generated by capacitively coupled radio-frequency discharge

    SciTech Connect

    Li, S.-Z.; Lim, J.-P.; Kang, Jung G.; Uhm, Han S.

    2006-09-15

    In this paper, the electrical discharge characteristics of plasmas generated in coaxial cylindrical electrodes capacitively powered by a radio-frequency power supply at atmospheric pressure are investigated with respect to helium and argon gases. The electrical discharge parameters, voltage (V), current (I), and power (P), are measured for both helium and argon plasmas, and the electron temperatures and electron densities for them are evaluated by means of the equivalent circuit model and the power balance equation. By comparison of the discharge characteristics of the helium and argon plasmas, it is found that the discrepant macroscopic characteristics of helium and argon plasma, viz., current and voltage characteristics and current and power characteristics, are owed to their own intrinsic microscopic parameters of the helium and argon atoms, such as the first excited energy, the ionization energy, the total cross section, and the atom mass. Furthermore, the influences of the additive gas, oxygen gas, on the electrical discharge characteristics are also investigated in the helium and argon plasmas, which are closely related to the electron temperature of plasmas.

  19. Simulation study of wave phenomena from the sheath region in single frequency capacitively coupled plasma discharges; field reversals and ion reflection

    SciTech Connect

    Sharma, S.; Turner, M. M.

    2013-07-15

    Capacitively coupled radio-frequency (RF) discharges have great significance for industrial applications. Collisionless electron heating in such discharges is important, and sometimes is the dominant mechanism. This heating is usually understood to originate in a stochastic interaction between electrons and the electric fields. However, other mechanisms may also be important. There is evidence of wave emission with a frequency near the electron plasma frequency, i.e., ω{sub pe}, from the sheath region in collisionless capacitive RF discharges. This is the result of a progressive breakdown of quasi-neutrality close to the electron sheath edge. These waves are damped in a few centimeters during their propagation from the sheath towards the bulk plasma. The damping occurs because of the Landau damping or some related mechanism. This research work reports that the emission of waves is associated with a field reversal during the expanding phase of the sheath. Trapping of electrons near to this field reversal region is observed. The amplitude of the wave increases with increasing RF current density amplitude J(tilde sign){sub 0} until some maximum is reached, beyond which the wave diminishes and a new regime appears. In this new regime, the density of the bulk plasma suddenly increases because of ion reflection, which occurs due to the presence of strong field reversal near sheath region. Our calculation shows that these waves are electron plasma waves. These phenomena occur under extreme conditions (i.e., higher J(tilde sign){sub 0} than in typical experiments) for sinusoidal current waveforms, but similar effects may occur with non-sinusoidal pulsed waveforms for conditions of experimental interest, because the rate of change of current is a relevant parameter. The effect of electron elastic collisions on plasma waves is also investigated.

  20. Patterns of disc-jet-wind coupling in black hole binaries

    NASA Astrophysics Data System (ADS)

    Fender, R.

    2015-07-01

    In this talk I will present the current state of the art in our understanding of the connection between accretion state and feedback in black hole X-ray binaries. In particular I will discuss how the X-ray accretion states, defined by their spectral and temporal properties, relate to phases of the production of relativistic (radio) jets and accretion disc winds. I will furthermore discuss how these patterns of behaviour contribute to the overall kinetic and radiative feedback during an outburst, and how comparable they may be to similar behaviour in neutron star X-ray binaries and supermassive black holes in active galactic nuclei.

  1. Tunable Plasmonic Coupling in Self-Assembled Binary Nanocrystal Super lattices Studied by Correlated Optical Microspectrophotometry and Electron Microscopy

    SciTech Connect

    Ye, XC; Chen, J; Diroll, BT; Murray, CB

    2013-03-01

    We study the plasmonic properties of self-assembled binary nanocrystal superlattices (BNSLs) using correlated optical microspectrophotometry and electron microscopy performed on individual BNSL domains. The strength of near-field couplings between adjacent plasmonic nanocrystals (NCs) can be systematically engineered by varying the NC size, composition, and the lattice symmetry of BNSLs, leading to broadband spectral tunability of the collective plasmonic response of BNSLs across the entire visible spectrum. Self-assembled multicomponent NC superlattices represent a versatile platform for the rational design of macroscopic three-dimensional plasmonic metamaterials with emergent optical characteristics.

  2. Pattern evolution caused by dynamic coupling between wetting and phase separation in binary liquid mixture containing glass particles

    NASA Astrophysics Data System (ADS)

    Tanaka, Hajime; Lovinger, Andew J.; Davis, Don D.

    1994-04-01

    We demonstrate here that the pattern evolution in a binary liquid mixture containing glass spheres is strongly affected by the dynamic coupling between phase separation and wetting. Because of the difference in the wettability to glass between the two phases, the glass particles are preferentially included in the more wettable phase. The resulting pattern is strongly dependent on whether the spheres are mobile or immobile. For a high density of mobile particles, we find that an initially random pattern of spheres transforms into an ordered pattern because of geometrical confinement of particles into the more wettable phase.

  3. Twin-capacitive shaft angle encoder with analog output signal

    NASA Technical Reports Server (NTRS)

    Hruby, R. J.; Wilson, R. L. (Inventor)

    1977-01-01

    A precision capacitive shaft encoder providing a dc signal corresponding to the angular position of a shaft is described. Two variable capacitances are coupled in tandem by a rotatable shaft. Each capacitor has a capacitance that varies linearly with a change in the angular position of the shaft. The sum of the two capacitances is always constant for any angular position of the shaft. Each capacitance is alternately coupled to a reference dc voltage and a discharge circuit. The capacitances are electrically coupled in series and the charge periodically acquired at the junction of the capacitance is a function of the position of the shaft. An error-compensating voltage is imposed on the junction when the capacitances are coupled to the reference voltages. The junction is coupled to sample-and-hold apparatus provided with a error-correcting circuit.

  4. Interpixel capacitance in nondestructive focal plane arrays

    NASA Astrophysics Data System (ADS)

    Moore, Andrew C.; Ninkov, Zoran; Forrest, William J.

    2004-01-01

    Inter-pixel capacitive coupling can exist in a non-destructive detector array if the detector nodes change voltage as they integrate charge and the design of the device allows for an electric field to exist between adjacent collection nodes. Small amounts of inter-pixel capacitance can cause large errors in the measurement of poissonian noise versus signal, and all subsequently derived measurements such as nodal capacitance and quantum efficiency. Crosstalk and MTF can also be significantly influenced by interpixel capacitance. Two 1k by 1k Raytheon SB226-based hybridized silicon PIN arrays were tested for nodal capacitance and MTF. Initial results indicated unexpected and unexplainably large nodal capacitance, poor MTF, and odd edge spread. It was hypothesized that inter-pixel capacitive coupling was responsible for these discrepancies. A stochastic method of measuring the coupling using 2D autocorrelation and Fourier Transform techniques was devised and implemented. Autocorrelation of the shot noise in the images revealed a correlation consistent with 3.2% interpixel capacitive coupling. When the effects of the measured interpixel capacitance were taken into account, the initially measured nodal capacitance of 56 fF was found to be 31% higher than the corrected nodal capacitance measurement of 43 fF. Large discrepancies between the theoretical and observed edge spread response were also greatly reduced. A simulation of the electric field in the PIN detector intrinsic region predicted an interpixel coupling very close to the observed coupling. Interpixel capacitance was also observed in a 2k by 2k Raytheon SB304-based InSb detector array, but was not strongly evident in a bare Raytheon SB226 multiplexer.

  5. Phase-shift effects on growth and transport of dust particles in VHF capacitively coupled silane discharges: Two dimensional fluid simulation

    SciTech Connect

    Liu Xiangmei; Song Yuanhong; Xu Xiang; Wang Younian

    2011-08-15

    A two-dimensional (2D) self-consistent fluid model is developed to describe the formation, subsequent growth, transport, and charging mechanisms of nanoparticles in a capacitively coupled silane discharge applied by two very high frequency (VHF) sources with phase shift. In this discharge process, large anions are produced by a series of chemical reactions of anions with silane molecules, while the lower limit of the initial nanoparticles are taken as large anions (Si{sub 12}H{sub 25}{sup -} and Si{sub 12}H{sub 24}{sup -}) to directly link the coagulation module with the nucleation module. And then, by using the coagulation module, the particle number density quickly decreases over several orders of magnitude, whereas the particle size strongly increases. We investigate in particular the growth of the nanoparticles ranging in size from {approx}1 to 50 nm in coagulation processes. The influences of controlled phase shifts between VHF (50 MHz) voltages on the electron density, electron temperature, nanoparticle uniformity, and deposition rate, are carefully studied. It is found from our simulation that the plasma density and nanoparticle density become center high and more uniform as the phase shift increases from 0 to 180 deg. Moreover, the role of phase-shift control in the silane discharge diluted with hydrogen gas is also discussed.

  6. An investigation of Ar metastable state density in low pressure dual-frequency capacitively coupled argon and argon-diluted plasmas

    SciTech Connect

    Liu, Wen-Yao; Xu, Yong Peng, Fei; Guo, Qian; Li, Xiao-Song; Zhu, Ai-Min; Liu, Yong-Xin; Wang, You-Nian

    2015-01-14

    An tunable diode laser absorption spectroscopy has been used to determine the Ar*({sup 3}P{sub 2}) and Ar*({sup 3}P{sub 0}) metastable atoms densities in dual-frequency capacitively coupled plasmas. The effects of different control parameters, such as high-frequency power, gas pressure and content of Ar, on the densities of two metastable atoms and electron density were discussed in single-frequency and dual-frequency Ar discharges, respectively. Particularly, the effects of the pressure on the axial profile of the electron and Ar metastable state densities were also discussed. Furthermore, a simple rate model was employed and its results were compared with experiments to analyze the main production and loss processes of Ar metastable states. It is found that Ar metastable state is mainly produced by electron impact excitation from the ground state, and decayed by diffusion and collision quenching with electrons and neutral molecules. Besides, the addition of CF{sub 4} was found to significantly increase the metastable destruction rate by the CF{sub 4} quenching, especially for large CF{sub 4} content and high pressure, it becomes the dominant depopulation process.

  7. Pulse-biased etching of Si3N4-layer in capacitively-coupled plasmas for nano-scale patterning of multi-level resist structures.

    PubMed

    Lee, Hyelim; Kim, Sechan; Choi, Gyuhyun; Lee, Nae-Eung

    2014-12-01

    Pulse-biased plasma etching of various dielectric layers is investigated for patterning nano-scale, multi-level resist (MLR) structures composed of multiple layers via dual-frequency, capacitively-coupled plasmas (CCPs). We compare the effects of pulse and continuous-wave (CW) biasing on the etch characteristics of a Si3N4 layer in CF4/CH2F2/O2/Aretch chemistries using a dual-frequency, superimposed CCP system. Pulse-biasing conditions using a low-frequency power source of 2 MHz were varied by controlling duty ratio, period time, power, and the gas flow ratio in the plasmas generated by the 27.12 MHz high-frequency power source. Application of pulse-biased plasma etching significantly affected the surface chemistry of the etched Si3N4 surfaces, and thus modified the etching characteristics of the Si3N4 layer. Pulse-biased etching was successfully applied to patterning of the nano-scale line and space pattern of Si3N4 in the MLR structure of KrF photoresist/bottom anti-reflected coating/SiO2/amorphous carbon layer/Si3N4. Pulse-biased etching is useful for tuning the patterning of nano-scale dielectric hard-mask layers in MLR structures. PMID:25971085

  8. The effect of dust on the electron heating in capacitively coupled H2/SiH4 single- and dual-frequency discharges

    NASA Astrophysics Data System (ADS)

    Schüngel, Edmund; Mohr, Sebastian; Iwashita, Shinya; Schulze, Julian; Czarnetzki, Uwe

    2013-09-01

    Hydrogen diluted silane discharges exhibit a high dust concentration under typical application conditions. Therefore, the role of dust in fundamental plasma processes needs to be understood. We study a capacitively coupled rf discharge in H2/SiH4 using Phase Resolved Emission Spectroscopy, two-dimensional laser light scattering on the dust particles as well as current and voltage measurements. The results show that the electron heating is strongly affected by the presence of dust particles. In particular, a mode transition occurs from the traditional α-mode to a bulk drift field mode (Ω-mode), if the amount of dust is increased. An analytical model of the electron dynamics in Ω-mode has been developed. An asymmetric dust particle density profile, e.g. due to a gas temperature gradient, induces an asymmetry in the electron heating and, thereby, in the ion density profile of a single frequency parallel plate discharge. In electrically asymmetric discharges, the discharge asymmetry can usually be controlled via the phase angle between the applied harmonics. It is found that the Electrical Asymmetry Effect works in discharges operated in both α- or Ω-mode, as the width of the control interval is almost independent of the dust distribution. Funded by the German Federal Ministry for the Environment (0325210B) and the Ruhr-University Research Department Plasma.

  9. Investigating the formation and the properties of monoalkyl carbonates in aqueous medium using capillary electrophoresis with capacitively coupled contactless conductivity detection.

    PubMed

    Vidal, Denis Tadeu Rajh; Nogueira, Thiago; Saito, Renata Mayumi; do Lago, Claudimir Lucio

    2011-04-01

    Although alkyl carbonic acids (ACAs) and their salts are referred to as instable species in aqueous medium, we demonstrate that a monoalkyl carbonate (MAC) can in fact be easily formed from bicarbonate and an alcohol even in the presence of a high amount of water. A CE system with two capacitively coupled contactless conductivity detectors (C⁴Ds) was used to obtain different parameters about these species and their reactions. Based on the mobilities obtained for a series of alcohols ranging from 1 to 5 carbons, the coefficients of diffusion and the hydrodynamic radii were calculated. When compared with the equivalent carboxylates, MACs have radii systematically smaller. Although the precise pK(a) values of the ACAs could not be obtained, because of the fast decomposition in acid medium, it was possible, for the first time, to show that they are below 4.0. This result suggests that the acidity of an ACA is quite similar to the first hydrogen of H₂CO₃. Using a new approach to indirectly calibrate the C⁴D, the kinetic constants and the equilibrium constants of formation were also obtained. The results suggest that the increase in the chain length makes the MACs less stable and more inert. PMID:21413029

  10. Simple and robust method for lithium traces determination in drinking water by atomic emission using low-power capacitively coupled plasma microtorch and microspectrometer.

    PubMed

    Zsigmond, Andreea R; Frentiu, Tiberiu; Ponta, Michaela; Frentiu, Maria; Petreus, Dorin

    2013-12-15

    A method for Li determination in drinking water using atomic emission spectrometry in a new low-power Ar capacitively coupled plasma microtorch (15 W, 0.6 L min(-1)) with a detection limit of 0.013 μg L(-1) was developed. The method is based on external calibration in the presence of a buffering solution containing 5 mg L(-1) Na, K, Ca, Mg added both to calibration standards and water samples. The statistical validation on 31 bottled drinking water samples (0.4-2140 μg L(-1) Li) using the Bland and Altman test and regression analysis has shown results similar to those obtained by the standard additions method. The buffering solution approach is simpler than the standard additions and has demonstrated good intra- and interday precision, accuracy and robustness. It was successfully applied over a wide concentration range of Li and multimineral matrix with a pooled precision of 2.5-3.5% and 99±9% accuracy.

  11. Absolute CF{sub 2} density and gas temperature measurements by absorption spectroscopy in dual-frequency capacitively coupled CF{sub 4}/Ar plasmas

    SciTech Connect

    Liu, Wen-Yao; Xu, Yong Peng, Fei; Gong, Fa-Ping; Li, Xiao-Song; Zhu, Ai-Min; Liu, Yong-Xin; Wang, You-Nian

    2014-10-15

    Broadband ultraviolet absorption spectroscopy has been used to determine the CF{sub 2} radical density in dual-frequency capacitively coupled CF{sub 4}/Ar plasmas, using the CF{sub 2} A{sup ~1}B{sub 1}←X{sup ~1}A{sub 1} system of absorption spectrum. The rotational temperature of ground state CF{sub 2} and excited state CF was also estimated by using A{sup ~1}B{sub 1}←X{sup ~1}A{sub 1} system and B{sup 2}Δ−X{sup 2}Π system, respectively. The translational gas temperature was deduced from the Doppler width of the Ar{sup *}({sup 3}P{sub 2}) and Ar{sup *}({sup 3}P{sub 0}) metastable atoms absorption line by using the tunable diode laser absorption spectroscopy. The rotational temperatures of the excited state CF are about 100 K higher than those of ground state CF{sub 2}, and about 200 K higher than the translational gas temperatures. The dependences of the radical CF{sub 2} density, electron density, electron temperature, rotational temperature, and gas temperature on the high frequency power and pressure have been analyzed. Furthermore, the production and loss mechanisms of CF{sub 2} radical and the gas heating mechanisms have also been discussed.

  12. A H2 very high frequency capacitively coupled plasma inactivates glyceraldehyde 3-phosphate dehydrogenase(GapDH) more efficiently than UV photons and heat combined

    NASA Astrophysics Data System (ADS)

    Stapelmann, Katharina; Lackmann, Jan-Wilm; Buerger, Ines; Bandow, Julia Elisabeth; Awakowicz, Peter

    2014-02-01

    Plasma sterilization is a promising alternative to commonly used sterilization techniques, because the conventional methods suffer from certain limitations, e.g. incompatibility with heat-sensitive materials, or use of toxic agents. However, plasma-based sterilization mechanisms are not fully understood yet. A low-pressure very high frequency capacitively coupled plasma is used to investigate the impact of a hydrogen discharge on the protein glyceraldehyde 3-phosphate dehydrogenase (GapDH). GapDH is an enzyme of glycolysis. As a part of the central metabolism, it occurs in nearly all organisms from bacteria to humans. The plasma is investigated with absolutely calibrated optical emission spectroscopy in order to identify and to quantify plasma components that can contribute to enzyme inactivation. The contribution of UV photons and heat to GapDH inactivation is investigated separately, and neither seems to be a major factor. In order to investigate the mechanisms of GapDH inactivation by the hydrogen discharge, samples are investigated for etching, induction of amino acid backbone breaks, and chemical modifications. While neither etching nor strand breaks are observed, chemical modifications occur at different amino acid residues of GapDH. Deamidations of asparagines as well as methionine and cysteine oxidations are detected after VHF-CCP treatment. In particular, oxidation of the cysteine in the active centre is known to lead to GapDH inactivation.

  13. Enhanced Macroscopic Quantum Tunneling in Capacitively Coupled BiPb2201 Single-Layered Intrinsic Josephson Junctions

    NASA Astrophysics Data System (ADS)

    Nomura, Yoshiki; Mizuno, Takaaki; Kambara, Hitoshi; Nakagawa, Yuya; Kakeya, Itsuhiro

    2015-01-01

    Macroscopic quantum tunneling (MQT) in an intrinsic Josephson junction (IJJ) stack of Bi1.9Pb0.1Sr1.39La0.63CuO6+δ (BiPb2201) has been investigated. For the first switch, from superconducting to the first resistive branch in current-voltage characteristics, the crossover between MQT and thermal activation (TA) takes place at 0.6 K. On the other hand, for the second switch, the MQT-TA crossover temperature is increased to 2.0 K. This result is interpreted as follows: the MQT rate of the second switch is enhanced by the charge coupling between adjacent IJJs as well as in Bi2Sr2CaCu2O8+δ. We consider that the enhancement of the MQT rate is a common feature among bismuth-cuprates with single and double CuO2 layers in their crystal structures.

  14. Tuning the ITO work function by capacitively coupled plasma and its application in inverted organic solar cells

    NASA Astrophysics Data System (ADS)

    Fang, Ming; Zhang, Chunmei; Chen, Qiang

    2016-11-01

    In this paper, we investigated the performance of inverted organic solar cells (OSCs) with plasma-treated indium tin oxide (ITO) as the cathode for omitting an electron transport layer. The Ar plasma was produced by capcitively coupled plasma setup under 20 Pa chamber pressure. For the device with the structure of plasma-treated ITO/P3HT:PCBM/MoO3/Ag, a power conversion efficiency (PCE) of 3.22% was achieved, whereas PCE of 1.13% was recorded from the device fabricated with the pristine ITO. The photovoltaic performance was found to be dependent on the applied power of plasma. After analyzing by atomic force microscopy (AFM) and X-ray photoelectron spectroscopy (XPS), we concluded that the chemical component variation of ITOs surface resulted in the decrease of ITO work function, which meant that the ITO Fermi level became shallow relative to the vacuum level. The low work function of ITO should be responsible for the improvement of inverted OSCs because of the better energy level alignment between ITO and the photoactive layer.

  15. Infinitely high selective inductively coupled plasma etching of an indium tin oxide binary mask structure for extreme ultraviolet lithography

    SciTech Connect

    Park, Y. R.; Ahn, J. H.; Kim, J. S.; Kwon, B. S.; Lee, N.-E.; Kang, H. Y.; Hwangbo, C. K.; Ahn, Jinho; Seo, Hwan Seok

    2010-07-15

    Currently, extreme ultraviolet lithography (EUVL) is being investigated for next generation lithography. Among the core EUVL technologies, mask fabrication is of considerable importance due to the use of new reflective optics with a completely different configuration than those of conventional photolithography. This study investigated the etching properties of indium tin oxide (ITO) binary mask materials for EUVL, such as ITO (absorber layer), Ru (capping/etch-stop layer), and a Mo-Si multilayer (reflective layer), by varying the Cl{sub 2}/Ar gas flow ratio, dc self-bias voltage (V{sub dc}), and etch time in inductively coupled plasmas. The ITO absorber layer needs to be etched with no loss in the Ru layer on the Mo-Si multilayer for fabrication of the EUVL ITO binary mask structure proposed here. The ITO layer could be etched with an infinitely high etch selectivity over the Ru etch-stop layer in Cl{sub 2}/Ar plasma even with a very high overetch time.

  16. A jet emission model to probe the dynamics of accretion and ejection coupling in black hole X-ray binaries

    NASA Astrophysics Data System (ADS)

    Malzac, Julien

    2016-07-01

    Compact jets are probably the most common form of jets in X-ray binaries and Active Galactic Nuclei. They seem to be present in all sources in the so-called hard X-ray spectral state. They are characterised by a nearly flat Spectral Energy Distribution (SED) extending from the radio to the infrared bands. This emission is usually interpreted as partially self absorbed synchrotron emission from relativistic leptons accelerated in the jet. The observed flat spectral shape requires energy dissipation and acceleration of particules over a wide range of distances along the jet. This distributed energy dissipation is likely to be powered by internal shocks caused by fluctuations of the outflow velocity. I will discuss such an internal shock model in the context of black hole binaries. I will show that internal shocks can produce the observed SEDs and also predict a strong, wavelength dependent, variability that resembles the observed one. The assumed velocity fluctuations of the jet must originate in the accretion flow. The model thus predicts a strong connection between the observable properties of the jet in the radio to IR bands, and the variability of the accretion flow as observed in X-rays. If the model is correct, this offers a unique possibility to probe the dynamics of the coupled accretion and ejection processes leading to the formation of compact jets.

  17. Electron–phonon coupling in Ni-based binary alloys with application to displacement cascade modeling

    NASA Astrophysics Data System (ADS)

    Samolyuk, G. D.; Béland, L. K.; Stocks, G. M.; Stoller, R. E.

    2016-05-01

    Energy transfer between lattice atoms and electrons is an important channel of energy dissipation during displacement cascade evolution in irradiated materials. On the assumption of small atomic displacements, the intensity of this transfer is controlled by the strength of electron–phonon (el–ph) coupling. The el–ph coupling in concentrated Ni-based alloys was calculated using electronic structure results obtained within the coherent potential approximation. It was found that Ni0.5Fe0.5, Ni0.5Co0.5 and Ni0.5Pd0.5 are ordered ferromagnetically, whereas Ni0.5Cr0.5 is nonmagnetic. Since the magnetism in these alloys has a Stoner-type origin, the magnetic ordering is accompanied by a decrease of electronic density of states at the Fermi level, which in turn reduces the el–ph coupling. Thus, the el–ph coupling values for all alloys are approximately 50% smaller in the magnetic state than for the same alloy in a nonmagnetic state. As the temperature increases, the calculated coupling initially increases. After passing the Curie temperature, the coupling decreases. The rate of decrease is controlled by the shape of the density of states above the Fermi level. Introducing a two-temperature model based on these parameters in 10 keV molecular dynamics cascade simulation increases defect production by 10–20% in the alloys under consideration.

  18. Electron phonon coupling in Ni-based binary alloys with application to displacement cascade modeling

    DOE PAGESBeta

    Samolyuk, German D.; Stocks, George Malcolm; Stoller, Roger E.

    2016-04-01

    Energy transfer between lattice atoms and electrons is an important channel of energy dissipation during displacement cascade evolution in irradiated materials. On the assumption of small atomic displacements, the intensity of this transfer is controlled by the strength of electron–phonon (el–ph) coupling. The el–ph coupling in concentrated Ni-based alloys was calculated using electronic structure results obtained within the coherent potential approximation. It was found that Ni0.5Fe0.5, Ni0.5Co0.5 and Ni0.5Pd0.5 are ordered ferromagnetically, whereas Ni0.5Cr0.5 is nonmagnetic. Since the magnetism in these alloys has a Stoner-type origin, the magnetic ordering is accompanied by a decrease of electronic density of states atmore » the Fermi level, which in turn reduces the el–ph coupling. Thus, the el–ph coupling values for all alloys are approximately 50% smaller in the magnetic state than for the same alloy in a nonmagnetic state. As the temperature increases, the calculated coupling initially increases. After passing the Curie temperature, the coupling decreases. The rate of decrease is controlled by the shape of the density of states above the Fermi level. Introducing a two-temperature model based on these parameters in 10 keV molecular dynamics cascade simulation increases defect production by 10–20% in the alloys under consideration.« less

  19. Electron-phonon coupling in Ni-based binary alloys with application to displacement cascade modeling

    NASA Astrophysics Data System (ADS)

    Samolyuk, G. D.; Béland, L. K.; Stocks, G. M.; Stoller, R. E.

    2016-05-01

    Energy transfer between lattice atoms and electrons is an important channel of energy dissipation during displacement cascade evolution in irradiated materials. On the assumption of small atomic displacements, the intensity of this transfer is controlled by the strength of electron-phonon (el-ph) coupling. The el-ph coupling in concentrated Ni-based alloys was calculated using electronic structure results obtained within the coherent potential approximation. It was found that Ni0.5Fe0.5, Ni0.5Co0.5 and Ni0.5Pd0.5 are ordered ferromagnetically, whereas Ni0.5Cr0.5 is nonmagnetic. Since the magnetism in these alloys has a Stoner-type origin, the magnetic ordering is accompanied by a decrease of electronic density of states at the Fermi level, which in turn reduces the el-ph coupling. Thus, the el-ph coupling values for all alloys are approximately 50% smaller in the magnetic state than for the same alloy in a nonmagnetic state. As the temperature increases, the calculated coupling initially increases. After passing the Curie temperature, the coupling decreases. The rate of decrease is controlled by the shape of the density of states above the Fermi level. Introducing a two-temperature model based on these parameters in 10 keV molecular dynamics cascade simulation increases defect production by 10-20% in the alloys under consideration.

  20. Capacitive label reader

    DOEpatents

    Arlowe, H.D.

    1983-07-15

    A capacitive label reader includes an outer ring transmitting portion, an inner ring transmitting portion, and a plurality of insulated receiving portions. A label is the mirror-image of the reader except that identifying portions corresponding to the receiving portions are insulated from only one of two coupling elements. Positive and negative pulses applied, respectively, to the two transmitting rings biased a CMOS shift register positively to either a 1 or 0 condition. The output of the CMOS may be read as an indication of the label.

  1. Bistable Magnetoresistance Switching in Exchange-Coupled CoFe2O4-Fe3O4 Binary Nanocrystal Superlattices by Self-Assembly and Thermal Annealing

    SciTech Connect

    Chen, J; Ye, XC; Oh, SJ; Kikkawa, JM; Kagan, CR; Murray, CB

    2013-02-01

    Self-assembly of multicomponent nanocrystal superlattices provides a modular approach to the design of metamaterials by choosing constituent nanocrystal building blocks with desired physical properties and engineering the interparticle coupling. In this work, we report the self-assembly of binary nanocrystal superlattices composed of magnetically hard CoFe2O4 nanocrystals and magnetically soft Fe3O4 nanocrystals. Both NaZn13- and MgZn2-type CoFe2O4-Fe3O4 binary nanocrystal superlattices have been formed by the liquid-air interfacial assembly approach. Exchange coupling is achieved in both types of binary superlattices after thermal annealing under vacuum at 400 degrees C. The exchange-coupled CoFe2O4-Fe3O4 binary nanocrystal superlattices show single-phase magnetization switching behavior and magnetoresistance switching behavior below 200 K. The NaZn13-type CoFe2O4-Fe3O4 binary nanocrystal superlattices annealed at 500 degrees C even exhibit bistable magnetoresistance switching behavior at room temperature constituting a simple nonvolatile memory function.

  2. Disc-jet coupling in the Terzan 5 neutron star X-ray binary EXO 1745-248

    NASA Astrophysics Data System (ADS)

    Tetarenko, A. J.; Bahramian, A.; Sivakoff, G. R.; Tremou, E.; Linares, M.; Tudor, V.; Miller-Jones, J. C. A.; Heinke, C. O.; Chomiuk, L.; Strader, J.; Altamirano, D.; Degenaar, N.; Maccarone, T.; Patruno, A.; Sanna, A.; Wijnands, R.

    2016-07-01

    We present the results of Very Large Array, Australia Telescope Compact Array, and Swift X-ray Telescope observations of the 2015 outburst of the transient neutron star X-ray binary (NSXB), EXO 1745-248, located in the globular cluster Terzan 5. Combining (near-) simultaneous radio and X-ray measurements, we measure a correlation between the radio and X-ray luminosities of L_R∝ L_X^β with β =1.68^{+0.10}_{-0.09}, linking the accretion flow (probed by X-ray luminosity) and the compact jet (probed by radio luminosity). While such a relationship has been studied in multiple black hole X-ray binaries (BHXBs), this work marks only the third NSXB with such a measurement. Constraints on this relationship in NSXBs are strongly needed, as comparing this correlation between different classes of XB systems is key in understanding the properties that affect the jet production process in accreting objects. Our best-fitting disc-jet coupling index for EXO 1745-248 is consistent with the measured correlation in NSXB 4U 1728-34 (β = 1.5 ± 0.2) but inconsistent with the correlation we fit using the most recent measurements from the literature of NSXB Aql X-1 (β =0.76^{+0.14}_{-0.15}). While a similar disc-jet coupling index appears to hold across multiple BHXBs in the hard accretion state, this does not appear to be the case with the three NSXBs measured so far. Additionally, the normalization of the EXO 1745-248 correlation is lower than the other two NSXBs, making it one of the most radio faint XBs ever detected in the hard state. We also report the detection of a type-I X-ray burst during this outburst, where the decay time-scale is consistent with hydrogen burning.

  3. Estimation of Leakage Potential of Selected Sites in Interstate and Tri-State Canals Using Geostatistical Analysis of Selected Capacitively Coupled Resistivity Profiles, Western Nebraska, 2004

    USGS Publications Warehouse

    Vrabel, Joseph; Teeple, Andrew P.; Kress, Wade H.

    2009-01-01

    With increasing demands for reliable water supplies and availability estimates, groundwater flow models often are developed to enhance understanding of surface-water and groundwater systems. Specific hydraulic variables must be known or calibrated for the groundwater-flow model to accurately simulate current or future conditions. Surface geophysical surveys, along with selected test-hole information, can provide an integrated framework for quantifying hydrogeologic conditions within a defined area. In 2004, the U.S. Geological Survey, in cooperation with the North Platte Natural Resources District, performed a surface geophysical survey using a capacitively coupled resistivity technique to map the lithology within the top 8 meters of the near-surface for 110 kilometers of the Interstate and Tri-State Canals in western Nebraska and eastern Wyoming. Assuming that leakage between the surface-water and groundwater systems is affected primarily by the sediment directly underlying the canal bed, leakage potential was estimated from the simple vertical mean of inverse-model resistivity values for depth levels with geometrically increasing layer thickness with depth which resulted in mean-resistivity values biased towards the surface. This method generally produced reliable results, but an improved analysis method was needed to account for situations where confining units, composed of less permeable material, underlie units with greater permeability. In this report, prepared by the U.S. Geological Survey in cooperation with the North Platte Natural Resources District, the authors use geostatistical analysis to develop the minimum-unadjusted method to compute a relative leakage potential based on the minimum resistivity value in a vertical column of the resistivity model. The minimum-unadjusted method considers the effects of homogeneous confining units. The minimum-adjusted method also is developed to incorporate the effect of local lithologic heterogeneity on water

  4. Effects of Bias Pulsing on Etching of SiO2 Pattern in Capacitively-Coupled Plasmas for Nano-Scale Patterning of Multi-Level Hard Masks.

    PubMed

    Kim, Sechan; Choi, Gyuhyun; Chae, Heeyeop; Lee, Nae-Eung

    2016-05-01

    In order to study the effects of bias pulsing on the etching characteristics of a silicon dioxide (SiO2) layer using multi-level hard mask (MLHM) structures of ArF photoresist/bottom anti-reflected coating/SiO2/amorphous carbon layer (ACL)/SiO2, the effects of bias pulsing conditions on the etch characteristics of a SiO2 layer with an ACL mask pattern in C4F8/CH2F2/O2/Ar etch chemistries were investigated in a dual-frequency capacitively-coupled plasma (CCP) etcher. The effects of the pulse frequency, duty ratio, and pulse-bias power in the 2 MHz low-frequency (LF) power source were investigated in plasmas generated by a 27.12 MHz high-frequency (HF) power source. The etch rates of ACL and SiO2 decreased, but the etch selectivity of SiO2/ACL increased with decreasing duty ratio. When the ACL and SiO2 layers were etched with increasing pulse frequency, no significant change was observed in the etch rates and etch selectivity. With increasing LF pulse-bias power, the etch rate of ACL and SiO2 slightly increased, but the etch selectivity of SiO2/ACL decreased. Also, the precise control of the critical dimension (CD) values with decreasing duty ratio can be explained by the protection of sidewall etching of SiO2 by increased passivation. Pulse-biased etching was successfully applied to the patterning of the nano-scale line and space of SiO2 using an ACL pattern. PMID:27483889

  5. Effect of Embedded RF Pulsing for Selective Etching of SiO2 in the Dual-Frequency Capacitive Coupled Plasmas.

    PubMed

    Kim, Nam Hun; Jeon, Min Hwan; Kim, Tae Hyung; Yeom, Geun Young

    2015-11-01

    The characteristics of embedded pulse plasma using 60 MHz radio frequency as the source power and 2 MHz radio frequency as the bias power were investigated for the etching of SiO2 masked with an amorphous carbon layer (ACL) using an Ar/C4F8/O2 gas mixture. Especially, the effects of the different pulse duty ratio of the embedded dual-frequency pulsing between source power and bias power on the characteristics on the plasma and SiO2 etching were investigated. The experiment was conducted by varying the source duty percentage from 90 to 30% while bias duty percentage was fixed at 50%. Among the different duty ratios, the source duty percentage of 60% with the bias duty percentage of 50% exhibited the best results in terms of etch profile and etch selectivity. The change of the etch characteristics by varying the duty ratios between the source power and bias power was believed to be related to the different characteristics of gas dissociation, fluorocarbon passivation, and ion bombardment observed during the different source/bias pulse on/off combinations. In addition, the instantaneous high electron temperature peak observed during each initiation of the source pulse-on period appeared to affect the etch characteristics by significant gas dissociation. The optimum point for the SiO2 etching with the source/bias pulsed dual-frequency capacitively coupled plasma system was obtained by avoiding this instant high electron temperature peak while both the source power and bias power were pulsed almost together, therefore, by an embedded RF pulsing. PMID:26726572

  6. The role of the metastable O2(b{{}^{1}}{\\Sigma}_{\\text {g}}^{+} ) and energy-dependent secondary electron emission yields in capacitively coupled oxygen discharges

    NASA Astrophysics Data System (ADS)

    Hannesdottir, H.; Gudmundsson, J. T.

    2016-10-01

    The effects of including the singlet metastable molecule O2(b{{}1}Σ\\text{g}+ ) in the discharge model of a capacitively coupled rf driven oxygen discharge are explored. We furthermore examine the addition of energy-dependent secondary electron emission yields from the electrodes to the discharge model. The one-dimensional object-oriented particle-in-cell Monte Carlo collision code oopd1 is used for this purpose, with the oxygen discharge model considering the species {{\\text{O}}2}≤ft({{\\text{X}}3}Σ\\text{g}-\\right) , {{\\text{O}}2}≤ft({{\\text{a}}1}{{Δ }\\text{g}}\\right) , {{\\text{O}}2}≤ft({{\\text{b}}1}Σ\\text{g}+\\right) , O(3P), O(1D), \\text{O}2+ , O+, O-, and electrons. The effects on particle density profiles, the electron heating rate profile, the electron energy probability function and the sheath width are explored including and excluding the metastable oxygen molecules and secondary electron emission. Earlier we have demonstrated that adding the metastable O2(a{{}1}{{Δ }\\text{g}} ) to the discharge model changes the electron heating from having contributions from both bulk and sheath heating to being dominated by sheath heating for pressures above 50 mTorr. We find that including the metastable O2(b{{}1}Σ\\text{g}+ ) further decreases the ohmic heating and the effective electron temperature in the bulk region. The effective electron temperature in the electronegative core is found to be less than 1 eV in the pressure range 50-200 mTorr which agrees with recent experimental findings. Furthermore, we find that including an energy-dependent secondary electron emission yield for \\text{O}2+ -ions has a significant influence on the discharge properties, including decreased sheath width.

  7. Effect of source frequency and pulsing on the SiO2 etching characteristics of dual-frequency capacitive coupled plasma

    NASA Astrophysics Data System (ADS)

    Kim, Hoe Jun; Jeon, Min Hwan; Mishra, Anurag Kumar; Kim, In Jun; Sin, Tae Ho; Yeom, Geun Young

    2015-01-01

    A SiO2 layer masked with an amorphous carbon layer (ACL) has been etched in an Ar/C4F8 gas mixture with dual frequency capacitively coupled plasmas under variable frequency (13.56-60 MHz)/pulsed rf source power and 2 MHz continuous wave (CW) rf bias power, the effects of the frequency and pulsing of the source rf power on the SiO2 etch characteristics were investigated. By pulsing the rf power, an increased SiO2 etch selectivity was observed with decreasing SiO2 etch rate. However, when the rf power frequency was increased, not only a higher SiO2 etch rate but also higher SiO2 etch selectivity was observed for both CW and pulse modes. A higher CF2/F ratio and lower electron temperature were observed for both a higher source frequency mode and a pulsed plasma mode. Therefore, when the C 1s binding states of the etched SiO2 surfaces were investigated using X-ray photoelectron spectroscopy (XPS), the increase of C-Fx bonding on the SiO2 surface was observed for a higher source frequency operation similar to a pulsed plasma condition indicating the increase of SiO2 etch selectivity over the ACL. The increase of the SiO2 etch rate with increasing etch selectivity for the higher source frequency operation appears to be related to the increase of the total plasma density with increasing CF2/F ratio in the plasma. The SiO2 etch profile was also improved not only by using the pulsed plasma but also by increasing the source frequency.

  8. Capacitively Coupled Resistivity measurements to determine frequency-dependent electrical parameters in periglacial environment—theoretical considerations and first field tests

    NASA Astrophysics Data System (ADS)

    Przyklenk, A.; Hördt, A.; Radić, T.

    2016-08-01

    Capacitively Coupled Resistivity (CCR) is conventionally used to emulate DC resistivity measurements and may provide important information about the ice content of material in periglacial areas. The application of CCR theoretically enables the determination of both electrical parameters, that is, the resistivity and the electrical permittivity, by analysing magnitude and phase shift spectra. The electrical permittivity may dominate the impedance, especially in periglacial areas or regions of hydrogeological interest. However, previous theoretical work suggested that the phase shift may strongly depend on electrode height above ground, implying that electrode height must be known with great accuracy to determine electrical permittivity. Here, we demonstrate with laboratory test measurements, theoretical modelling and by analysing the Jacobian matrix of the inversion that the sensitivity towards electrode height is drastically reduced if the electrical permittivity is frequency dependent in a way that is typical for ice. For the first time, we used a novel broad-band CCR device `Chameleon' for a field test located in one of the ridge galleries beneath the crest of Mount Zugspitze. A permanently ice covered bottom of a tunnel was examined. For the inversion of the measured spectra, the frequency dependence of the electrical parameters was parametrized in three different ways: A Debye Model for pure ices, a Cole-Cole Model for pure ices and a dual Cole-Cole Model including interfacial water additionally. The frequency-dependent resistivity and permittivity spectra obtained from the inversion, including low- and high-frequency limits, agree reasonably well with laboratory and field measurements reported in the literature.

  9. Exploring the possibilities of capacitively coupled contactless conductivity detection in combination with liquid chromatography for the analysis of polar compounds using aminoglycosides as test case.

    PubMed

    Jankovics, Péter; Chopra, Shruti; El-Attug, Mohamed N; Cabooter, Deirdre; Wolfs, Kris; Noszál, Béla; Van Schepdael, Ann; Adams, Erwin

    2015-08-10

    The analysis of highly polar (often charged) compounds which lack a strong UV absorbing chromophore is really challenging. Despite the numerous analytical methods published, the demand for a simple, robust and cheap technique for their analysis still persists. Here, reversed phase (RP) liquid chromatography (LC) with capacitively coupled contactless conductivity detection (C(4)D) was explored for the first time as a possible method for separation and detection of various aminoglycoside (AMG) antibiotics which were taken as typical test compounds: tobramycin (TOB), spectinomycin, streptomycin, amikacin, kanamycin A and kanamycin B. C(4)D was performed using a commercially available as well as a laboratory made cell. As ion-pairing reagents (IPR) four perfluorinated carboxylic acids were used: pentafluoropropionic acid, heptafluorobutyric acid, nonafluoropentanoic acid (NFPA) and pentadecafluorooctanoic acid (PDFOA). 0.125 mM NFPA-acetonitrile (ACN) (90:10) or 0.125 mM PDFOA-ACN (70:30) as mobile phases were suitable to detect TOB with reasonable retention times. However, NFPA was preferred for practical reasons. Its applicable concentration range in the mobile phase was strongly restricted by loss of chromatographic performance at lower levels and excessive background conductivity at higher levels. Overall repeatability and robustness of the method were rather poor which was explained by the relatively low IPR levels. Selectivity between the tested AMGs was mainly influenced by the number of protonated amino groups per molecule making it impossible to separate compounds of equal net charges. Problems encountered with gradient elution, hydrophilic interaction liquid chromatography (HILIC) and separation at high pH without IPRs are also discussed. PMID:25549929

  10. A comparative study of capacitively coupled HBr/He, HBr/Ar plasmas for etching applications: Numerical investigation by fluid model

    SciTech Connect

    Gul, Banat; Aman-ur-Rehman

    2015-10-15

    Fluid model has been applied to perform a comparative study of hydrogen bromide (HBr)/He and HBr/Ar capacitively coupled plasma discharges that are being used for anisotropic etching process. This model has been used to identify the most dominant species in HBr based plasmas. Our simulation results show that the neutral species like H and Br, which are the key player in chemical etching, have bell shape distribution, while ions like HBr{sup +}, Br{sup +}, which play a dominant rule in the physical etching, have double humped distribution and show peaks near electrodes. It was found that the dilution of HBr by Ar and/or He results in an increase in electron density and electron temperature, which results in more ionization and dissociation and hence higher densities of neutral and charged species can be achieved. The ratio of positive ion flux to the neutral flux increases with an increase in additive gas fraction. Compare to HBr/He plasma, the HBr/Ar plasma shows a maximum change in the ion density and flux and hence the etching rate can be considered in the ion-assisted and in the ion-flux etch regime in HBr/Ar discharge. The densities of electron and other dominant species in HBr/Ar plasma are higher than those of HBr/He plasma. The densities and fluxes of the active neutrals and positive ions for etching and subsequently chemical etching versus physical sputtering in HBr/Ar and HBr/He plasmas discharge can be controlled by tuning gas mixture ratio and the desire etching can be achieved.

  11. Effect on plasma and etch-rate uniformity of controlled phase shift between rf voltages applied to powered electrodes in a triode capacitively coupled plasma reactor

    SciTech Connect

    Sung, Dougyong; Jeong, Sangmin; Park, Youngmin; Volynets, Vladimir N.; Ushakov, Andrey G.; Kim, Gon-Ho

    2009-01-15

    The influence of the phase shift between rf voltages applied to the powered electrodes on plasma parameters and etch characteristics was studied in a very high-frequency (VHF) capacitively coupled plasma (CCP) triode reactor. rf voltages at 100 MHz were simultaneously applied to the top and bottom electrodes having a controlled phase shift between them, which could be varied between 0 deg. and 360 deg. Several plasma and process characteristics were measured as a function of the phase shift: (i) radial profiles of plasma-emission intensity, (ii) line-of-sight averaged plasma-emission intensity, and (iii) radial profiles of blanket SiO{sub 2} etching rate over a 300 mm wafer. Radial profiles of plasma emission were obtained using the scanning optical probe. It has been shown that all the measured characteristics strongly depend on the phase shift: (i) plasma-emission intensity is minimal at phase shift equal to 0 deg. and maximal at 180 deg. for all radial positions, while the emission radial profile changes from bell-shaped distribution with considerable nonuniformity at 0 deg. to a much more flattened distribution at 180 deg.; (ii) line-of-sight averaged plasma-emission intensity shows a similar dependence on the phase shift with minimum and maximum at 0 deg. and 180 deg., respectively; and (iii) the etch-rate radial profile at 180 deg. shows a much better uniformity as compared to that at 0 deg. Some of these results can be qualitatively explained by the redistribution of plasma currents that flow between the electrodes and also from the electrodes to the grounded wall with the phase shift. We suggest that the phase-shift effect can be used to improve the plasma and etch-rate spatial uniformity in VHF-CCP triode reactors.

  12. Coupled peritectic growth of the {alpha}- and {gamma}-phases in binary titanium aluminides

    SciTech Connect

    Meissen, F.; Busse, P.; Laakmann, J.

    1996-12-31

    Coupled growth during three phase equilibrium solidification is well known from directionally solidified eutectic systems, and was recently generated in monotectic systems. Several theories predict a stationary peritectic reaction and coupled growth of the properitectic and the peritectic phases therefore should be possible. In spite of these theories coupled growth has not been observed up to now. The TiAl system was selected for further investigation on this topic because of its technical relevance and the fact that it meets the condition mentioned for coupled growth. In a Bridgman laboratory furnace, TiAl with 53.4 at.% Al was directionally solidified with solidification rates v between 0.025 mm/min and 0.1 mm/min and a temperature gradient up to 20 K/mm. The resulting microstructures, analyzed using optical and scanning microscopy with EDX and WDX, consist of two phases parallel to the growth direction. At v = 0.05 to 0.1 mm/min, the alloy solidifies as properitectical {alpha}, which subsequently eutectoidally transforms to a substructure of {alpha}{sub 2}-Ti{sub 3}Al and {gamma}-TiAl, and peritectic {gamma}. The lamellar {alpha}{sub 2}/{gamma}-substructure is oriented parallel to the growth direction. The experimental results were compared with the existing theoretical models of a stationary peritectic reaction and the possibility of metastable eutectic growth was discussed.

  13. Capacitively Coupled Resistivity Survey of Selected Irrigation Canals Within the North Platte River Valley, Western Nebraska and Eastern Wyoming, 2004 and 2007-2009

    USGS Publications Warehouse

    Burton, Bethany L.; Johnson, Michaela R.; Vrabel, Joseph; Imig, Brian H.; Payne, Jason D.; Tompkins, Ryan E.

    2009-01-01

    Due to water resources of portions of the North Platte River basin being designated as over-appropriated by the State of Nebraska Department of Natural Resources (DNR), the North Platte Natural Resources District (NPNRD), in cooperation with the DNR, is developing an Integrated Management Plan (IMP) for groundwater and surface water in the NPNRD. As part of the IMP, a three-dimensional numerical finite difference groundwater-flow model is being developed to evaluate the effectiveness of using leakage of water from selected irrigation canal systems to manage groundwater recharge. To determine the relative leakage potential of the upper 8 m of the selected irrigation canals within the North Platte River valley in western Nebraska and eastern Wyoming, the U.S. Geological Survey performed a land-based capacitively coupled (CC) resistivity survey along nearly 630 km of 13 canals and 2 laterals in 2004 and from 2007 to 2009. These 13 canals were selected from the 27 irrigation canals in the North Platte valley due to their location, size, irrigated area, and relation to the active North Platte valley flood plain and related paleochannels and terrace deposits where most of the saturated thickness in the alluvium exists. The resistivity data were then compared to continuous cores at 62 test holes down to a maximum depth of 8 m. Borehole electrical conductivity (EC) measurements at 36 of those test holes were done to correlate resistivity values with grain sizes in order to determine potential vertical leakage along the canals as recharge to the underlying alluvial aquifer. The data acquired in 2004, as well as the 25 test hole cores from 2004, are presented elsewhere. These data were reprocessed using the same updated processing and inversion algorithms used on the 2007 through 2009 datasets, providing a consistent and complete dataset for all collection periods. Thirty-seven test hole cores and borehole electrical conductivity measurements were acquired based on the 2008

  14. Comparison of vacuum ultra-violet emission of Ar/CF4 and Ar/CF3I capacitively coupled plasmas

    NASA Astrophysics Data System (ADS)

    Zotovich, A.; Proshina, O.; el Otell, Z.; Lopaev, D.; Rakhimova, T.; Rakhimov, A.; de Marneffe, J.-F.; Baklanov, M. R.

    2016-10-01

    Spectra in the vacuum-ultra violet range (VUV, 30 nm-200 nm) as well as in the ultra-violet(UV) and visible ranges (UV+vis, 200 nm-800 nm) were measured from Ar/CF3I and Ar/CF4 discharges. The discharges were generated in an industrial 300 mm capacitively coupled plasma source with 27 MHz radio-frequency power. It was seen that the measured spectra were strongly modified. This is mainly due to absorption, especially by CF3I, and Ar self-trapping along the line of sight, towards the detector and in the plasma itself. The estimated unabsorbed VUV spectra were revealed from the spectra of mixtures with low fluorocarbon gas content by means of normalization with unabsorbed I* emission, at 206 nm, and CF2\\ast band (1B1(0,v‧,0){{\\to}1} A1(0,{{\\text{v}}\\prime \\prime} ,0)) emission between 230 nm and 430 nm. Absolute fluences of UV CF2\\ast emission were derived using hybrid 1-dimensional (1D) particle-in-cell (PIC) Monte-Carlo (MC) model calculations. Absolute calibration of the VUV emission was performed using these calculated values from the model, which has never been done previously for real etch conditions in an industrial chamber. It was seen that the argon resonant lines play a significant role in the VUV spectra. These lines are dominant in the case of etching recipes close to the standard ones. The restored unabsorbed spectra confirm that replacement of conventional CF4 etchant gas with CF3I in low-k etching recipes leads to an increase in the overall VUV emission intensity. However, emission from Ar exhibited the most intense peaks. Damage to low-k SiCOH glasses by the estimated VUV was calculated for blanket samples with pristine k-value of 2.2. The calculations were then compared with Fourier transform infrared (FTIR) data for samples exposed to the similar experimental conditions in the same reactor. It was shown that Ar emission plays the most significant role in VUV-induced damage.

  15. The interplay between magnetism, structure, and strong electron-phonon coupling in binary FeAs under pressure

    SciTech Connect

    Jeffries, J R; Butch, N P; Cynn, H; Saha, S R; Kirshenbaum, K; Weir, S T; Vohra, Y K; Paglione, J

    2010-11-10

    Unlike the ferropnictide superconductors, which crystallize in a tetragonal crystal structure, binary FeAs forms in an orthorhombic crystal structure, where the local atomic environment resembles a highly distorted variant of the FeAs{sub 4} tetrahedral building block of the ferropnictide superconductors. However, like the parent compounds of the ferropnictide superconductors, FeAs undergoes magnetic ordering at low temperatures, with no evidence favoring a superconducting ground state at ambient pressure. We employ pressure-dependent electrical transport and x-ray diffraction measurements using diamond anvil cells to characterize the magnetic state and the structure as a function of pressure. While the structure persists up to 25 GPa, compressing continuously with pressure, magnetotransport measurements suggests that the magnetic state is destroyed near 11 GPa. The magnetic transition temperature is found to be remarkably robust under pressure, and transport measurements suggest that a dynamical structural instability coupled to the Fermi surface via a strong electron-phonon interaction may play an important role in enabling magnetism in FeAs.

  16. Theoretical study of surface plasmons coupling in transition metallic alloy 2D binary grating

    NASA Astrophysics Data System (ADS)

    Dhibi, Abdelhak; Khemiri, Mehdi; Oumezzine, Mohamed

    2016-05-01

    The excitation of a surface plasmon polariton (SPP) wave on a metal-air interface by a 2D diffraction grating is numerically investigated. The grating consists of homogeneous alloys of two metals of a formula AxB1-x, or three metals of a formula AxByCz, where A, B and C could be silver (Ag), copper (Cu), gold (Au) or aluminum (Al). It is observed that all the alloys of two metals present a very small change of surface plasmon resonance (SPR) irrespective of composition x. Moreover, the addition of 25% of Al to two metals alloy is insufficient to change the SPR curves. The influence of the different grating parameters is discussed in details using rigorous coupled-wave analysis (RCWA) method. Furthermore, the SPR is highly dependent on grating periods (dx and dy) and the height of the grating h. The results reveal that dx= dy= 700 nm, h=40 nm and duty cycle w=0.5 are the optimal parameters for exciting SPP.

  17. Capacitively coupled and direct-current resistivity surveys of selected reaches of Cozad, Thirty-Mile, Orchard-Alfalfa, Kearney, and Outlet Canals in Nebraska, 2012-13

    USGS Publications Warehouse

    Hobza, Christopher M.; Burton, Bethany L.; Lucius, Jeffrey E.; Tompkins, Ryan E.

    2014-01-01

    Understanding the spatial characteristics of leakage from canals is critical to effectively managing and utilizing water resources for irrigation and hydroelectric purposes. Canal leakage in some parts of Nebraska is the primary source of water for groundwater recharge and helps maintain the base flow of streams. Because surface-water supplies depend on the streamflow of the Platte River and the available water stored in upstream reservoirs, water managers seek to minimize conveyance losses, which can include canal leakage. The U.S. Geological Survey, in cooperation with the Central Platte Natural Resources District and Nebraska Public Power District, used capacitively coupled (CC) and direct-current (DC) resistivity techniques for continuous resistivity profiling to map near-surface lithologies near and underlying the Cozad, Thirty-Mile, Orchard-Alfalfa, Kearney, and Outlet Canals. Approximately 84 kilometers (km) of CC-resistivity data were collected along the five canals. The CC-resistivity data were compared with results from continuous sediment cores and electrical conductivity logs. Generally, the highest resistivities were recorded at the upstream reaches of the Cozad, Thirty-Mile, and Orchard-Alfalfa canals where flood-plain deposits of silt and clay mantle coarser channel deposits of sand and gravel. The finer grained deposits gradually thicken with increasing distance away from the Platte River. Consequently, for many surveyed reaches the thickness of fine-grained deposits exceeded the 8-meter depth of investigation. A detailed geophysical investigation along a 5-km reach of the Outlet Canal southwest of North Platte, Nebraska, used CC and DC resistivity to examine the condition of a compacted-core bank structure and characterized other potential controls on areas of focused seepage. CC-resistivity data, collected along the 5-km study reach, were compared with continuous sediment cores and DC-resistivity data collected near a selected seep near Outlet

  18. Shielded capacitive electrode

    DOEpatents

    Kireeff Covo, Michel

    2013-07-09

    A device is described, which is sensitive to electric fields, but is insensitive to stray electrons/ions and unlike a bare, exposed conductor, it measures capacitively coupled current while rejecting currents due to charged particle collected or emitted. A charged particle beam establishes an electric field inside the beam pipe. A grounded metallic box with an aperture is placed in a drift region near the beam tube radius. The produced electric field that crosses the aperture generates a fringe field that terminates in the back surface of the front of the box and induces an image charge. An electrode is placed inside the grounded box and near the aperture, where the fringe fields terminate, in order to couple with the beam. The electrode is negatively biased to suppress collection of electrons and is protected behind the front of the box, so the beam halo cannot directly hit the electrode and produce electrons. The measured signal shows the net potential (positive ion beam plus negative electrons) variation with time, as it shall be observed from the beam pipe wall.

  19. Effect of C:F Deposition on Etching of SiCOH Low-k Films in CHF3 60 MHz/2 MHz Dual-Frequency Capacitively Coupled Plasma

    NASA Astrophysics Data System (ADS)

    Shi, Guofeng; Ye, Chao; Xu, Yijun; Huang, Hongwei; Yuan, Yuan; Ning, Zhaoyuan

    2010-08-01

    Effect of C:F deposition on SiCOH etching in a CHF3 dual-frequency capacitively couple plasma, driven by a high-frequency source of 60 MHz (HF) and a low-frequency source of 2 MHz (LF) simultaneously, is investigated. With the increase in LF power, the change of C:F layer from dense C:F layer to porous C:F layer and further to C:F filling gaps was observed, which led to the transition from films deposition to films etching. The change of C:F layer is related to the bombardment by energetic ions and CF2 concentration in the plasma. As the LF power increased to 35~40 W, the energetic ions and the low CF2 concentration led to a suppression of C:F deposition. Therefore, the SiCOH films can be etched at higher LF power.

  20. Effects of gas flow rate on the etch characteristics of a low- k sicoh film with an amorphous carbon mask in dual-frequency CF4/C4F8/Ar capacitively-coupled plasmas

    NASA Astrophysics Data System (ADS)

    Kwon, Bong-Soo; Lee, Hea-Lim; Lee, Nae-Eung; Kim, Chang-Young; Choi, Chi Kyu

    2013-01-01

    Highly selective nanoscale etching of a low-dielectric constant (low- k) organosilicate (SiCOH) layer using a mask pattern of chemical-vapor-deposited (CVD) amorphous carbon layer (ACL) was carried out in CF4/C4F8/Ar dual-frequency superimposed capacitively-coupled plasmas. The etching characteristics of the SiCOH layers, such as the etch rate, etch selectivity, critical dimension (CD), and line edge roughness (LER) during the plasma etching, were investigated by varying the C4F8 flow rate. The C4F8 gas flow rate primarily was found to control the degree of polymerization and to cause variations in the selectivity, CD and LER of the patterned SiCOH layer. Process windows for ultra-high etch selectivity of the SiCOH layer to the CVD ACL are formed due to the disproportionate degrees of polymerization on the SiCOH and the ACL surfaces.

  1. Variable Synthetic Capacitance

    NASA Technical Reports Server (NTRS)

    Kleinberg, L. L.

    1986-01-01

    Feedback amplifier circuit synthesizes electronically variable capacitance. Variable Synthetic Capacitor is amplifier circuit with follower/feedback configuration. Effective input capacitance depends on input set current. If synthetic capacitor is connected across resonant element of oscillator, oscillator frequency controlled via input set current. Circuit especially suitable for fine frequency adjustments of piezoelectric-crystal or inductor/capacitor resonant oscillators.

  2. Capacitance measuring device

    DOEpatents

    Andrews, W.H. Jr.

    1984-08-01

    A capacitance measuring circuit is provided in which an unknown capacitance is measured by comparing the charge stored in the unknown capacitor with that stored in a known capacitance. Equal and opposite voltages are repetitively simultaneously switched onto the capacitors through an electronic switch driven by a pulse generator to charge the capacitors during the ''on'' portion of the cycle. The stored charge is compared by summing discharge currents flowing through matched resistors at the input of a current sensor during the ''off'' portion of the switching cycle. The net current measured is thus proportional to the difference in value of the two capacitances. The circuit is capable of providing much needed accuracy and stability to a great variety of capacitance-based measurement devices at a relatively low cost.

  3. An associative capacitive network based on nanoscale complementary resistive switches for memory-intensive computing.

    PubMed

    Kavehei, Omid; Linn, Eike; Nielen, Lutz; Tappertzhofen, Stefan; Skafidas, Efstratios; Valov, Ilia; Waser, Rainer

    2013-06-01

    We report on the implementation of an Associative Capacitive Network (ACN) based on the nondestructive capacitive readout of two Complementary Resistive Switches (2-CRSs). ACNs are capable of performing a fully parallel search for Hamming distances (i.e. similarity) between input and stored templates. Unlike conventional associative memories where charge retention is a key function and hence, they require frequent refresh cycles, in ACNs, information is retained in a nonvolatile resistive state and normal tasks are carried out through capacitive coupling between input and output nodes. Each device consists of two CRS cells and no selective element is needed, therefore, CMOS circuitry is only required in the periphery, for addressing and read-out. Highly parallel processing, nonvolatility, wide interconnectivity and low-energy consumption are significant advantages of ACNs over conventional and emerging associative memories. These characteristics make ACNs one of the promising candidates for applications in memory-intensive and cognitive computing, switches and routers as binary and ternary Content Addressable Memories (CAMs) and intelligent data processing.

  4. An associative capacitive network based on nanoscale complementary resistive switches for memory-intensive computing

    NASA Astrophysics Data System (ADS)

    Kavehei, Omid; Linn, Eike; Nielen, Lutz; Tappertzhofen, Stefan; Skafidas, Efstratios; Valov, Ilia; Waser, Rainer

    2013-05-01

    We report on the implementation of an Associative Capacitive Network (ACN) based on the nondestructive capacitive readout of two Complementary Resistive Switches (2-CRSs). ACNs are capable of performing a fully parallel search for Hamming distances (i.e. similarity) between input and stored templates. Unlike conventional associative memories where charge retention is a key function and hence, they require frequent refresh cycles, in ACNs, information is retained in a nonvolatile resistive state and normal tasks are carried out through capacitive coupling between input and output nodes. Each device consists of two CRS cells and no selective element is needed, therefore, CMOS circuitry is only required in the periphery, for addressing and read-out. Highly parallel processing, nonvolatility, wide interconnectivity and low-energy consumption are significant advantages of ACNs over conventional and emerging associative memories. These characteristics make ACNs one of the promising candidates for applications in memory-intensive and cognitive computing, switches and routers as binary and ternary Content Addressable Memories (CAMs) and intelligent data processing.

  5. Investigating the role of capacitive coupling between the operating table and the return electrode of an electrosurgery unit in the modification of the current density distribution within the patients’ body

    PubMed Central

    2013-01-01

    Background Electrosurgery units are widely employed in modern surgery. Advances in technology have enhanced the safety of these devices, nevertheless, accidental burns are still regularly reported. This study focuses on possible causes of sacral burns as complication of the use of electrosurgery. Burns are caused by local densifications of the current, but the actual pathway of current within patient’s body is unknown. Numerical electromagnetic analysis can help in understanding the issue. Methods To this aim, an accurate heterogeneous model of human body (including seventy-seven different tissues), electrosurgery electrodes, operating table and mattress was build to resemble a typical surgery condition. The patient lays supine on the mattress with the active electrode placed onto the thorax and the return electrode on his back. Common operating frequencies of electrosurgery units were considered. Finite Difference Time Domain electromagnetic analysis was carried out to compute the spatial distribution of current density within the patient’s body. A differential analysis by changing the electrical properties of the operating table from a conductor to an insulator was also performed. Results Results revealed that distributed capacitive coupling between patient body and the conductive operating table offers an alternative path to the electrosurgery current. The patient’s anatomy, the positioning and the different electromagnetic properties of tissues promote a densification of the current at the head and sacral region. In particular, high values of current density were located behind the sacral bone and beneath the skin. This did not occur in the case of non-conductive operating table. Conclusion Results of the simulation highlight the role played from capacitive couplings between the return electrode and the conductive operating table. The concentration of current density may result in an undesired rise in temperature, originating burns in body region far from

  6. System for Measuring Capacitance

    NASA Technical Reports Server (NTRS)

    McNichol, Randal S. (Inventor)

    2001-01-01

    A system has been developed for detecting the level of a liquid in a tank wherein a capacitor positioned in the tank has spaced plates which are positioned such that the dielectric between the plates will be either air or the liquid, depending on the depth of the liquid in the tank. An oscillator supplies a sine wave current to the capacitor and a coaxial cable connects the capacitor to a measuring circuit outside the tank. If the cable is very long or the capacitance to be measured is low, the capacitance inherent in the coaxial cable will prevent an accurate reading. To avoid this problem, an inductor is connected across the cable to form with the capacitance of the cable a parallel resonant circuit. The impedance of the parallel resonant circuit is infinite, so that attenuation of the measurement signal by the stray cable capacitance is avoided.

  7. Capacitance pressure sensor

    DOEpatents

    Eaton, William P.; Staple, Bevan D.; Smith, James H.

    2000-01-01

    A microelectromechanical (MEM) capacitance pressure sensor integrated with electronic circuitry on a common substrate and a method for forming such a device are disclosed. The MEM capacitance pressure sensor includes a capacitance pressure sensor formed at least partially in a cavity etched below the surface of a silicon substrate and adjacent circuitry (CMOS, BiCMOS, or bipolar circuitry) formed on the substrate. By forming the capacitance pressure sensor in the cavity, the substrate can be planarized (e.g. by chemical-mechanical polishing) so that a standard set of integrated circuit processing steps can be used to form the electronic circuitry (e.g. using an aluminum or aluminum-alloy interconnect metallization).

  8. Capacitive chemical sensor

    DOEpatents

    Manginell, Ronald P; Moorman, Matthew W; Wheeler, David R

    2014-05-27

    A microfabricated capacitive chemical sensor can be used as an autonomous chemical sensor or as an analyte-sensitive chemical preconcentrator in a larger microanalytical system. The capacitive chemical sensor detects changes in sensing film dielectric properties, such as the dielectric constant, conductivity, or dimensionality. These changes result from the interaction of a target analyte with the sensing film. This capability provides a low-power, self-heating chemical sensor suitable for remote and unattended sensing applications. The capacitive chemical sensor also enables a smart, analyte-sensitive chemical preconcentrator. After sorption of the sample by the sensing film, the film can be rapidly heated to release the sample for further analysis. Therefore, the capacitive chemical sensor can optimize the sample collection time prior to release to enable the rapid and accurate analysis of analytes by a microanalytical system.

  9. Simulating Capacitances to Silicon Quantum Dots: Breakdown of the Parallel Plate Capacitor Model

    NASA Astrophysics Data System (ADS)

    Thorbeck, Ted; Fujiwara, Akira; Zimmerman, Neil M.

    2012-09-01

    Many electrical applications of quantum dots rely on capacitively coupled gates; therefore, to make reliable devices we need those gate capacitances to be predictable and reproducible. We demonstrate in silicon nanowire quantum dots that gate capacitances are reproducible to within 10% for nominally identical devices. We demonstrate the experimentally that gate capacitances scale with device dimensions. We also demonstrate that a capacitance simulator can be used to predict measured gate capacitances to within 20%. A simple parallel plate capacitor model can be used to predict how the capacitances change with device dimensions; however, the parallel plate capacitor model fails for the smallest devices because the capacitances are dominated by fringing fields. We show how the capacitances due to fringing fields can be quickly estimated.

  10. Coupling ion-exchangers with inexpensive activated carbon fiber electrodes to enhance the performance of capacitive deionization cells for domestic wastewater desalination.

    PubMed

    Liang, Peng; Yuan, Lulu; Yang, Xufei; Zhou, Shaoji; Huang, Xia

    2013-05-01

    A capacitive deionization (CDI) cell was built with electrodes made of an inexpensive commercial activated carbon fiber (ACF), and then modified by incorporating ion-exchangers into the cell compartment. Three modified CDI designs were tested: MCDI - a CDI with electrodes covered by ion-exchange membranes (IEMs) of the same polarity, FCDI - a CDI with electrodes covered by ion-exchange felts (IEFs), and R-MCDI - an MCDI with cell chamber packed with ion-exchange resin (IER) granules. The cell was operated in the batch reactor mode with an initial salt concentration of 1000 mg/L NaCl, a typical level of domestic wastewater. The desalination tests involved investigations of two consecutive operation stages of CDIs: electrical adsorption (at an applied voltage of 1.2 V) and desorption [including short circuit (SC) desorption and discharge (DC) desorption]. The R-MCDI showed the highest electric adsorption as measured in the present study by desalination rate [670 ± 20 mg/(L h)] and salt removal efficiency (90 ± 1%) at 60 min, followed by the MCDI [440 ± 15 mg/(L h) and 60 ± 2%, respectively]. The superior desalination performance of the R-MCDI over other designs was also affirmed by its highest charge efficiency (110 ± 7%) and fastest desorption rates at both the SC [1960 ± 15 mg/(L·h)] and DC [3000 ± 20 mg/(L·h)] modes. The desalination rate and salt removal efficiency of the R-MCDI increased from ∼270 mg/(L h) and 83% to ∼650 mg/(L h) and 98% respectively when the applied voltage increased from 0.6 V to 1.4 V, while decreased slightly when lowering the salt water flow rate that fed into the cell. The packing of IER granules in the R-MCDI provided additional surface area for ions transfer; meanwhile, according to the results of electrochemical impedance spectroscopy (EIS) analysis, it substantially lower down the R-MCDI's ohmic resistance, resulting in improved desalination performance.

  11. An instability due to the nonlinear coupling of p-modes to g-modes: Implications for coalescing neutron star binaries

    SciTech Connect

    Weinberg, Nevin N.; Arras, Phil; Burkart, Joshua

    2013-06-01

    A weakly nonlinear fluid wave propagating within a star can be unstable to three-wave interactions. The resonant parametric instability is a well-known form of three-wave interaction in which a primary wave of frequency ω {sub a} excites a pair of secondary waves of frequency ω {sub b} + ω {sub c} ≅ ω {sub a}. Here we consider a nonresonant form of three-wave interaction in which a low-frequency primary wave excites a high-frequency p-mode and a low-frequency g-mode such that ω {sub b} + ω {sub c} >> ω {sub a}. We show that a p-mode can couple so strongly to a g-mode of similar radial wavelength that this type of nonresonant interaction is unstable even if the primary wave amplitude is small. As an application, we analyze the stability of the tide in coalescing neutron star binaries to p-g mode coupling. We find that the equilibrium tide and dynamical tide are both p-g unstable at gravitational wave frequencies f {sub gw} ≳ 20 Hz and drive short wavelength p-g mode pairs to significant energies on very short timescales (much less than the orbital decay time due to gravitational radiation). Resonant parametric coupling to the tide is, by contrast, either stable or drives modes at a much smaller rate. We do not solve for the saturation of the p-g instability and therefore we cannot say precisely how it influences the evolution of neutron star binaries. However, we show that if even a single daughter mode saturates near its wave breaking amplitude, the p-g instability of the equilibrium tide will (1) induce significant orbital phase errors (Δφ ≳ 1 radian) that accumulate primarily at low frequencies (f {sub gw} ≲ 50 Hz) and (2) heat the neutron star core to a temperature of T ∼ 10{sup 10} K. Since there are at least ∼100 unstable p-g daughter pairs, Δφ and T are potentially much larger than these values. Tides might therefore significantly influence the gravitational wave signal and electromagnetic emission from coalescing neutron star binaries

  12. An Instability due to the Nonlinear Coupling of p-modes to g-modes: Implications for Coalescing Neutron Star Binaries

    NASA Astrophysics Data System (ADS)

    Weinberg, Nevin N.; Arras, Phil; Burkart, Joshua

    2013-06-01

    A weakly nonlinear fluid wave propagating within a star can be unstable to three-wave interactions. The resonant parametric instability is a well-known form of three-wave interaction in which a primary wave of frequency ω a excites a pair of secondary waves of frequency ω b + ω c ~= ω a . Here we consider a nonresonant form of three-wave interaction in which a low-frequency primary wave excites a high-frequency p-mode and a low-frequency g-mode such that ω b + ω c Gt ω a . We show that a p-mode can couple so strongly to a g-mode of similar radial wavelength that this type of nonresonant interaction is unstable even if the primary wave amplitude is small. As an application, we analyze the stability of the tide in coalescing neutron star binaries to p-g mode coupling. We find that the equilibrium tide and dynamical tide are both p-g unstable at gravitational wave frequencies f gw >~ 20 Hz and drive short wavelength p-g mode pairs to significant energies on very short timescales (much less than the orbital decay time due to gravitational radiation). Resonant parametric coupling to the tide is, by contrast, either stable or drives modes at a much smaller rate. We do not solve for the saturation of the p-g instability and therefore we cannot say precisely how it influences the evolution of neutron star binaries. However, we show that if even a single daughter mode saturates near its wave breaking amplitude, the p-g instability of the equilibrium tide will (1) induce significant orbital phase errors (Δphi >~ 1 radian) that accumulate primarily at low frequencies (f gw <~ 50 Hz) and (2) heat the neutron star core to a temperature of T ~ 1010 K. Since there are at least ~100 unstable p-g daughter pairs, Δphi and T are potentially much larger than these values. Tides might therefore significantly influence the gravitational wave signal and electromagnetic emission from coalescing neutron star binaries at much larger orbital separations than previously thought.

  13. Experimental investigations of electron density and ion energy distributions in dual-frequency capacitively coupled plasmas for Ar/CF{sub 4} and Ar/O{sub 2}/CF{sub 4} discharges

    SciTech Connect

    Liu, Jia; Liu, Yong-Xin; Gao, Fei; Wang, You-Nian; Bi, Zhen-Hua

    2014-01-07

    The electron density and ion energy distribution (IED) are investigated in low-pressure dual-frequency capacitively coupled Ar/CF{sub 4} (90%/10%) and Ar/O{sub 2}/CF{sub 4} (80%/10%/10%) plasmas. The relations between controllable parameters, such as high-frequency (HF) power, low-frequency (LF) power and gas pressure, and plasma parameters, such as electron density and IEDs, are studied in detail by utilizing a floating hairpin probe and an energy resolved quadrupole mass spectrometer, respectively. In our experiment, the electron density is mainly determined by the HF power and slightly influenced by the LF power. With increasing gas pressure, the electron density first goes up rapidly to a maximum value and then decreases at various HF and LF powers. The HF power also plays a considerable role in affecting the IEDs under certain conditions and the ion energy independently controlled by the LF source is discussed here. For clarity, some numerical results obtained from a two-dimensional fluid model are presented.

  14. Capacitive Feedthroughs for Medical Implants.

    PubMed

    Grob, Sven; Tass, Peter A; Hauptmann, Christian

    2016-01-01

    Important technological advances in the last decades paved the road to a great success story for electrically stimulating medical implants, including cochlear implants or implants for deep brain stimulation. However, there are still many challenges in reducing side effects and improving functionality and comfort for the patient. Two of the main challenges are the wish for smaller implants on one hand, and the demand for more stimulation channels on the other hand. But these two aims lead to a conflict of interests. This paper presents a novel design for an electrical feedthrough, the so called capacitive feedthrough, which allows both reducing the size, and increasing the number of included channels. Capacitive feedthroughs combine the functionality of a coupling capacitor and an electrical feedthrough within one and the same structure. The paper also discusses the progress and the challenges of the first produced demonstrators. The concept bears a high potential in improving current feedthrough technology, and could be applied on all kinds of electrical medical implants, even if its implementation might be challenging.

  15. Capacitive Feedthroughs for Medical Implants.

    PubMed

    Grob, Sven; Tass, Peter A; Hauptmann, Christian

    2016-01-01

    Important technological advances in the last decades paved the road to a great success story for electrically stimulating medical implants, including cochlear implants or implants for deep brain stimulation. However, there are still many challenges in reducing side effects and improving functionality and comfort for the patient. Two of the main challenges are the wish for smaller implants on one hand, and the demand for more stimulation channels on the other hand. But these two aims lead to a conflict of interests. This paper presents a novel design for an electrical feedthrough, the so called capacitive feedthrough, which allows both reducing the size, and increasing the number of included channels. Capacitive feedthroughs combine the functionality of a coupling capacitor and an electrical feedthrough within one and the same structure. The paper also discusses the progress and the challenges of the first produced demonstrators. The concept bears a high potential in improving current feedthrough technology, and could be applied on all kinds of electrical medical implants, even if its implementation might be challenging. PMID:27660602

  16. Capacitive Feedthroughs for Medical Implants

    PubMed Central

    Grob, Sven; Tass, Peter A.; Hauptmann, Christian

    2016-01-01

    Important technological advances in the last decades paved the road to a great success story for electrically stimulating medical implants, including cochlear implants or implants for deep brain stimulation. However, there are still many challenges in reducing side effects and improving functionality and comfort for the patient. Two of the main challenges are the wish for smaller implants on one hand, and the demand for more stimulation channels on the other hand. But these two aims lead to a conflict of interests. This paper presents a novel design for an electrical feedthrough, the so called capacitive feedthrough, which allows both reducing the size, and increasing the number of included channels. Capacitive feedthroughs combine the functionality of a coupling capacitor and an electrical feedthrough within one and the same structure. The paper also discusses the progress and the challenges of the first produced demonstrators. The concept bears a high potential in improving current feedthrough technology, and could be applied on all kinds of electrical medical implants, even if its implementation might be challenging. PMID:27660602

  17. Capacitive Feedthroughs for Medical Implants

    PubMed Central

    Grob, Sven; Tass, Peter A.; Hauptmann, Christian

    2016-01-01

    Important technological advances in the last decades paved the road to a great success story for electrically stimulating medical implants, including cochlear implants or implants for deep brain stimulation. However, there are still many challenges in reducing side effects and improving functionality and comfort for the patient. Two of the main challenges are the wish for smaller implants on one hand, and the demand for more stimulation channels on the other hand. But these two aims lead to a conflict of interests. This paper presents a novel design for an electrical feedthrough, the so called capacitive feedthrough, which allows both reducing the size, and increasing the number of included channels. Capacitive feedthroughs combine the functionality of a coupling capacitor and an electrical feedthrough within one and the same structure. The paper also discusses the progress and the challenges of the first produced demonstrators. The concept bears a high potential in improving current feedthrough technology, and could be applied on all kinds of electrical medical implants, even if its implementation might be challenging.

  18. Two-dimensional model of a capacitively coupled rf discharge and comparisons with experiments in the Gaseous Electronics Conference reference reactor

    NASA Astrophysics Data System (ADS)

    Boeuf, J. P.; Pitchford, L. C.

    1995-02-01

    We present results from a two-dimensional (2D) numerical fluid model of rf discharges in conditions close to recently published measurements of the spatial distribution of plasma density in the Gaseous Electronic Conference reference cell. The discharge is in pure argon at pressures in the 100 mtorr range, frequency 13.56 MHz, and rf voltage amplitudes on the order of 100 V. The model is based on solutions of the continuity, momentum (drift-diffusion), and energy equations for the electrons, continuity, and drift-diffusion equation for positive ions, coupled with the Poisson equation. The results of the model are qualitatively and quantitatively in good agreement with the experiments. The model predicts a maximum of plasma density off axis, as in the experiment. The ion current density on the electrode is also nonuniform, and increases radially in the conditions of the experiments. The effects of the rf voltage, pressure, and reactor geometry (electrode dimensions, gap length, guard rings, etc.) on the plasma properties and on the uniformity of the ion current on the powered electrode are also discussed. It is shown that the existence of a maximum of plasma density in the radial direction, in the conditions of the experiment, is due to the small value of the electrode spacing. The results show that the harmonic content of the discharge current is also geometry dependent. The comparisons show that 2D, three-moment fluid models can accurately describe the discharge and the effects of the chamber geometry on the plasma properties for pressure above the limit where collisionless electron heating does not play a significant role.

  19. Characterization of binary silver based alloys by nanosecond-infrared-laser-ablation-inductively coupled plasma-optical emission spectrometer

    NASA Astrophysics Data System (ADS)

    Márquez, Ciro; Sobral, Hugo

    2013-11-01

    A nanosecond infrared laser ablation (LA) system was examined to determine the composition of several silver-copper alloys through an inductively coupled plasma-optical emission spectrometer (ICP-OES). Samples with different concentrations were prepared and analyzed by atomic absorption, and ICP-OES after sample digestion, and compared with an energy-dispersive x-ray spectrometer-scanning electron microscopy (EDX-SEM). Elemental fractionation during the ablation process and within the ICP was investigated for different laser frequencies and fluences. Samples were used for optimizing and calibrating the coupling between LA to the ICP-OES system. Results obtained from the samples analysis were in agreement with those obtained by atomic absorption spectroscopy, ICP-OES and EDX-SEM, showing that fractionation was not significant for laser fluences higher than 55 J cm-2.

  20. Online capacitive densitometer

    DOEpatents

    Porges, K.G.

    1988-01-21

    This invention is an apparatus for measuring fluid density of mixed phase fluid flow. The apparatus employs capacitive sensing of the mixed phased flow combined with means for uniformizing the electric field between the capacitor plates to account for flow line geometry. From measurement of fluid density, the solids feedrate can be ascertained. 7 figs.

  1. Online capacitive densitometer

    DOEpatents

    Porges, Karl G.

    1990-01-01

    This invention is an apparatus for measuring fluid density of mixed phase fluid flow. The apparatus employs capacitive sensing of the mixed phased flow combined with means for uniformizing the electric field between the capacitor plates to account for flow line geometry. From measurement of fluid density, the solids feedrate can be ascertained.

  2. Digital capacitance measuring system

    NASA Technical Reports Server (NTRS)

    1973-01-01

    The hardware phase of a digital capacitance measuring system is presented with the major emphasis placed on the electrical design and operation. Test results are included of the three units fabricated. The system's interface is applicable to existing requirements for the space shuttle vehicle.

  3. Highly selective etching of silicon nitride to physical-vapor-deposited a-C mask in dual-frequency capacitively coupled CH{sub 2}F{sub 2}/H{sub 2} plasmas

    SciTech Connect

    Kim, J. S.; Kwon, B. S.; Heo, W.; Jung, C. R.; Park, J. S.; Shon, J. W.; Lee, N.-E.

    2010-01-15

    A multilevel resist (MLR) structure can be fabricated based on a very thin amorphous carbon (a-C) layer ( congruent with 80 nm) and Si{sub 3}N{sub 4} hard-mask layer ( congruent with 300 nm). The authors investigated the selective etching of the Si{sub 3}N{sub 4} layer using a physical-vapor-deposited (PVD) a-C mask in a dual-frequency superimposed capacitively coupled plasma etcher by varying the process parameters in the CH{sub 2}F{sub 2}/H{sub 2}/Ar plasmas, viz., the etch gas flow ratio, high-frequency source power (P{sub HF}), and low-frequency source power (P{sub LF}). They found that under certain etch conditions they obtain infinitely high etch selectivities of the Si{sub 3}N{sub 4} layers to the PVD a-C on both the blanket and patterned wafers. The etch gas flow ratio played a critical role in determining the process window for infinitely high Si{sub 3}N{sub 4}/PVD a-C etch selectivity because of the change in the degree of polymerization. The etch results of a patterned ArF photoresisit/bottom antireflective coating/SiO{sub x}/PVD a-C/Si{sub 3}N{sub 4} MLR structure supported the idea of using a very thin PVD a-C layer as an etch-mask layer for the Si{sub 3}N{sub 4} hard-mask pattern with a pattern width of congruent with 80 nm and high aspect ratio of congruent with 5.

  4. A miniaturized capacitively coupled plasma microtorch optical emission spectrometer and a Rh coiled-filament as small-sized electrothermal vaporization device for simultaneous determination of volatile elements from liquid microsamples: spectral and analytical characterization.

    PubMed

    Frentiu, Tiberiu; Darvasi, Eugen; Butaciu, Sinziana; Ponta, Michaela; Petreus, Dorin; Mihaltan, Alin I; Frentiu, Maria

    2014-11-01

    A low power and low argon consumption (13.56 MHz, 15 W, 150 ml min(-1)) capacitively coupled plasma microtorch interfaced with a low-resolution microspectrometer and a small-sized electrothermal vaporization Rh coiled-filament as liquid microsample introduction device into the plasma was investigated for the simultaneous determination of several volatile elements of interest for environment. Constructive details, spectral and analytical characteristics, and optimum operating conditions of the laboratory equipment for the simultaneous determination of Ag, Cd, Cu, Pb and Zn requiring low vaporization power are provided. The method involves drying of 10 μl sample at 100°C, vaporization at 1500°C and emission measurement by capture of 20 successive spectral episodes each at an integration time of 500 ms. Experiments showed that emission of elements and plasma background were disturbed by the presence of complex matrix and hot Ar flow transporting the microsample into plasma. The emission spectrum of elements is simple, dominated by the resonance lines. The analytical system provided detection limits in the ng ml(-1) range: 0.5(Ag); 1.5(Cd); 5.6(Cu); 20(Pb) and 3(Zn) and absolute detection limits of the order of pg: 5(Ag); 15(Cd); 56(Cu); 200(Pb) and 30(Zn). It was demonstrated the utility and capability of the miniaturized analytical system in the simultaneous determination of elements in soil and water sediment using the standard addition method to compensate for the non-spectral effects of alkali and earth alkaline elements. The analysis of eight certified reference materials exhibited reliable results with recovery in the range of 95-108% and precision of 0.5-9.0% for the five examined elements. The proposed miniaturized analytical system is attractive due to the simple construction of the electrothermal vaporization device and microtorch, low costs associated to plasma generation, high analytical sensitivity and easy-to-run for simultaneous multielemental

  5. Effect of electrode spacing on the density distributions of electrons, ions, and metastable and radical molecules in SiH{sub 4}/NH{sub 3}/N{sub 2}/He capacitively coupled plasmas

    SciTech Connect

    Kim, Ho Jun; Yang, Wonkyun; Joo, Junghoon

    2015-07-28

    Semiconductor fabrication often requires the deposition of hydrogenated silicon nitride (SiN{sub x}H{sub y}) film using SiH{sub 4}/NH{sub 3}/N{sub 2}/He capacitively coupled plasma (CCP) discharge. As analysis of the discharge geometry is essential to understanding CCP deposition, the effect of electrode spacing on the two-dimensional distributions of electrons, ions, and metastable and radical molecules was analyzed numerically using a fluid model. The simulation shows that the spatial variations in the ionization rates near the sheath become more obvious as the electrode spacing increases. In addition, as molecule-molecule gas-phase reactions are significantly affected by the local residence time, large electrode spacings are associated with significant volumetric losses for positive ions. Consequently, an increase of the electrode spacing leads axial density profiles of ions to change from bell shaped to double humped. However, NH{sub 4}{sup +} persistently maintains a bell-shaped axial density profile regardless of the degree of electrode spacing. We set the mole fraction of NH{sub 3} to only 1% of the total flow at the inlet, but NH{sub 4}{sup +} is the most abundant positive ion at the large electrode spacings. As the gas flow can transport the radicals around the space between the electrodes, we found that radical density distribution shifts toward the grounded electrode. The shift becomes pronounced as the electrode spacing increases. Finally, to validate our model, we compared the calculated deposition rate profile with the experimental data obtained along the wafer radius. According to our numerical results, the SiN{sub x}H{sub y} deposition rate decreases by approximately 16% when the electrode spacing increases from 9 to 20 mm.

  6. Capacitive skin characterization

    NASA Technical Reports Server (NTRS)

    Mcconnell, Robert; Manzo, Michael

    1992-01-01

    NASA is currently involved in research that utilizes a capacitive sensor that is used for proximity detection of objects. This sensor is sensitive to conductive and dielectric materials including metal objects and humans. The range of the sensor has been found to be about twelve inches. It is the goal of this research project to further characterize the sensor so that it can be tailored to specific requirements. The characterization of the sensor should be with respect to shield size, sensor size, object size, and object distance. The method of finite elements to calculate the capacitance of the sensor while varying different parameters was used. Each of the parameters was varied in turn, often by selecting data points from different runs. The plotted results are shown and an apparent functionality developed for each.

  7. Capacitive deionization of seawater

    SciTech Connect

    Farmer, J.C.; Fix, D.V.; Mack, G.V.

    1995-10-01

    Capacitive deionization with carbon aerogel electrodes is an efficient and economical new process for removing salt and impurities from water. Carbon aerogel is a material that enables the successful purification of water because of its high surface area, optimum pore size, and low electrical resistivity. The electrodes are maintained at a potential difference of about one volt; ions are removed from the water by the imposed electrostatic field and retained on the electrode surface until the polarity is reversed. The capacitive deionization of water with a stack of carbon aerogel electrodes has been successfully demonstrated. The overall process offers advantages when compared to conventional water-purification methods, requiring neither pumps, membranes, distillation columns, nor thermal heaters. Consequently, the overall process is both robust and energy efficient. The current state of technology development, commercialization, and potential applications of this process are reviewed.

  8. Electrical capacitance clearanceometer

    NASA Technical Reports Server (NTRS)

    Hester, Norbert J. (Inventor); Hornbeck, Charles E. (Inventor); Young, Joseph C. (Inventor)

    1992-01-01

    A hot gas turbine engine capacitive probe clearanceometer is employed to measure the clearance gap or distance between blade tips on a rotor wheel and its confining casing under operating conditions. A braze sealed tip of the probe carries a capacitor electrode which is electrically connected to an electrical inductor within the probe which is inserted into a turbine casing to position its electrode at the inner surface of the casing. Electrical power is supplied through a voltage controlled variable frequency oscillator having a tuned circuit in which the probe is a component. The oscillator signal is modulated by a change in electrical capacitance between the probe electrode and a passing blade tip surface while an automatic feedback correction circuit corrects oscillator signal drift. A change in distance between a blade tip and the probe electrode is a change in capacitance therebetween which frequency modulates the oscillator signal. The modulated oscillator signal which is then processed through a phase detector and related circuitry to provide an electrical signal is proportional to the clearance gap.

  9. Capacitively-coupled data receiver clipper stage

    NASA Technical Reports Server (NTRS)

    Saunders, F. W.

    1977-01-01

    Circuit technique compensates for dc offset and asymmetry in dc clipping levels, negates unbalance in input waveform that causes voltage offset at end of data word, blocks any dc component that is generated by asymmetrical operation of clipper, and improves data threshold detection.

  10. Multi-Channel Capacitive Sensor Arrays

    PubMed Central

    Wang, Bingnan; Long, Jiang; Teo, Koon Hoo

    2016-01-01

    In this paper, multi-channel capacitive sensor arrays based on microstrip band-stop filters are studied. The sensor arrays can be used to detect the proximity of objects at different positions and directions. Each capacitive sensing structure in the array is connected to an inductive element to form resonance at different frequencies. The resonances are designed to be isolated in the frequency spectrum, such that the change in one channel does not affect resonances at other channels. The inductive element associated with each capacitive sensor can be surface-mounted inductors, integrated microstrip inductors or metamaterial-inspired structures. We show that by using metamaterial split-ring structures coupled to a microstrip line, the quality factor of each resonance can be greatly improved compared to conventional surface-mounted or microstrip meander inductors. With such a microstrip-coupled split-ring design, more sensing elements can be integrated in the same frequency spectrum, and the sensitivity can be greatly improved. PMID:26821023

  11. Multi-Channel Capacitive Sensor Arrays.

    PubMed

    Wang, Bingnan; Long, Jiang; Teo, Koon Hoo

    2016-01-01

    In this paper, multi-channel capacitive sensor arrays based on microstrip band-stop filters are studied. The sensor arrays can be used to detect the proximity of objects at different positions and directions. Each capacitive sensing structure in the array is connected to an inductive element to form resonance at different frequencies. The resonances are designed to be isolated in the frequency spectrum, such that the change in one channel does not affect resonances at other channels. The inductive element associated with each capacitive sensor can be surface-mounted inductors, integrated microstrip inductors or metamaterial-inspired structures. We show that by using metamaterial split-ring structures coupled to a microstrip line, the quality factor of each resonance can be greatly improved compared to conventional surface-mounted or microstrip meander inductors. With such a microstrip-coupled split-ring design, more sensing elements can be integrated in the same frequency spectrum, and the sensitivity can be greatly improved. PMID:26821023

  12. Complex Capacitance Scaling in Ionic Liquids-filled Nanopores

    SciTech Connect

    Qiao, Rui; Huang, Jingsong; Meunier, Vincent; Sumpter, Bobby G; Peng, Wu

    2011-01-01

    Recent experiments have shown that the capacitance of sub-nanometer pores increases anomalously as the pore width decreases, thereby opening a new avenue for developing supercapacitors with enhanced energy density. However, this behavior is still subject to some controversy since its physical origins are not well understood. Using atomistic simulations, we show that the capacitance of slit-shaped nanopores in contact with room-temperature ionic liquids exhibits a U-shaped scaling behavior in pores with width from 0.75 to 1.26 nm. The left branch of the capacitance scaling curve directly corresponds to the anomalous capacitance increase and thus reproduces the experimental observations. The right branch of the curve indirectly agrees with experimental findings that so far have received little attention. The overall U-shaped scaling behavior provides insights on the origins of the difficulty in experimentally observing the pore-width dependent capacitance. We establish a theoretical framework for understanding the capacitance of electrical double layers in nanopores and provide mechanistic details into the origins of the observed scaling behavior. The framework highlights the critical role of ion solvation in controlling pore capacitance and the importance of choosing anion/cation couples carefully for optimal energy storage in a given pore system.

  13. Complex Capacitance Scaling in Ionic Liquids-Filled Nanopores

    SciTech Connect

    Sumpter, Bobby G

    2011-01-01

    Recent experiments have shown that the capacitance of subnanometer pores increases anomalously as the pore width decreases, thereby opening a new avenue for developing supercapacitors with enhanced energy density. However, this behavior is still subject to some controversy since its physical origins are not well understood. Using atomistic simulations, we show that the capacitance of slit-shaped nanopores in contact with room-temperature ionic liquids exhibits a U-shaped scaling behavior in pores with widths from 0.75 to 1.26 nm. The left branch of the capacitance scaling curve directly corresponds to the anomalous capacitance increase and thus reproduces the experimental observations. The right branch of the curve indirectly agrees with experimental findings that so far have received little attention. The overall U-shaped scaling behavior provides insights on the origins of the difficulty in experimentally observing the pore-width-dependent capacitance. We establish a theoretical framework for understanding the capacitance of electrical double layers in nanopores and provide mechanistic details into the origins of the observed scaling behavior. The framework highlights the critical role of 'ion solvation' in controlling pore capacitance and the importance of choosing anion/cation couples carefully for optimal energy storage in a given pore system.

  14. A compact, low input capacitance neural recording amplifier.

    PubMed

    Ng, K A; Xu, Yong Ping

    2013-10-01

    Conventional capacitively coupled neural recording amplifiers often present a large input load capacitance to the neural signal source and hence take up large circuit area. They suffer due to the unavoidable trade-off between the input capacitance and chip area versus the amplifier gain. In this work, this trade-off is relaxed by replacing the single feedback capacitor with a clamped T-capacitor network. With this simple modification, the proposed amplifier can achieve the same mid-band gain with less input capacitance, resulting in a higher input impedance and a smaller silicon area. Prototype neural recording amplifiers based on this proposal were fabricated in 0.35 μm CMOS, and their performance is reported. The amplifiers occupy smaller area and have lower input loading capacitance compared to conventional neural amplifiers. One of the proposed amplifiers occupies merely 0.056 mm(2). It achieves 38.1-dB mid-band gain with 1.6 pF input capacitance, and hence has an effective feedback capacitance of 20 fF. Consuming 6 μW, it has an input referred noise of 13.3 μVrms over 8.5 kHz bandwidth and NEF of 7.87. In-vivo recordings from animal experiments are also demonstrated.

  15. A simple and reproducible capacitive electrode.

    PubMed

    Spinelli, Enrique; Guerrero, Federico; García, Pablo; Haberman, Marcelo

    2016-03-01

    Capacitive Electrodes (CE) allow the acquisition of biopotentials through a dielectric layer, without the use of electrolytes, just by placing them on skin or clothing, but demands front-ends with ultra-high input impedances. This must be achieved while providing a path for bias currents, calling for ultra-high value resistors and special components and construction techniques. A simple CE that uses bootstrap techniques to avoid ultra-high value components and special materials is proposed. When electrodes are placed on the skin; that is, with coupling capacitances C(S) of around 100 pF, they present a noise level of 3.3 µV(RMS) in a 0.5-100 Hz bandwidth, which is appropriate for electrocardiography (ECG) measurements. Construction details of the CE and the complete circuit, including a fast recovery feature, are presented.

  16. Theoretical and experimental analysis of a piezoelectric plate connected to a negative capacitance at MHz frequencies

    NASA Astrophysics Data System (ADS)

    Mansoura, S. A.; Benard, P.; Morvan, B.; Maréchal, P.; Hladky-Hennion, A.-C.; Dubus, B.

    2015-11-01

    In this paper, a theoretical and experimental study of the electric impedance of a piezoelectric plate connected to a negative capacitance is performed in the MHz frequency range. The negative capacitance is realized with a circuit using current conveyors (CCII+). This circuit allows us to achieve important values of negative capacitance, of the same order of the static capacitance of the piezoelectric plate studied. Mason’s model is considered for the theoretical characterization of the piezoelectric plate connected to the negative capacitance circuit. The experimental results show a large tunability of the frequency of the piezoelectric parallel resonance over a range of 1.1 MHz to 1.28 MHz. Moreover, according to the value of the negative capacitance, the effective electromechanical coupling factor of the piezoelectric plate is evaluated. With a very good agreement with the theoretical estimation, an increase of approximately 50% of the effective electromechanical coupling factor is experimentally measured.

  17. COUPLING

    DOEpatents

    Frisch, E.; Johnson, C.G.

    1962-05-15

    A detachable coupling arrangement is described which provides for varying the length of the handle of a tool used in relatively narrow channels. The arrangement consists of mating the key and keyhole formations in the cooperating handle sections. (AEC)

  18. Programmable electronic synthesized capacitance

    NASA Technical Reports Server (NTRS)

    Kleinberg, Leonard L. (Inventor)

    1987-01-01

    A predetermined and variable synthesized capacitance which may be incorporated into the resonant portion of an electronic oscillator for the purpose of tuning the oscillator comprises a programmable operational amplifier circuit. The operational amplifier circuit has its output connected to its inverting input, in a follower configuration, by a network which is low impedance at the operational frequency of the circuit. The output of the operational amplifier is also connected to the noninverting input by a capacitor. The noninverting input appears as a synthesized capacitance which may be varied with a variation in gain-bandwidth product of the operational amplifier circuit. The gain-bandwidth product may, in turn, be varied with a variation in input set current with a digital to analog converter whose output is varied with a command word. The output impedance of the circuit may also be varied by the output set current. This circuit may provide very small ranges in oscillator frequency with relatively large control voltages unaffected by noise.

  19. Binary stars.

    PubMed

    Paczynacuteski, B

    1984-07-20

    Most stars in the solar neighborhood are either double or multiple systems. They provide a unique opportunity to measure stellar masses and radii and to study many interesting and important phenomena. The best candidates for black holes are compact massive components of two x-ray binaries: Cygnus X-1 and LMC X-3. The binary radio pulsar PSR 1913 + 16 provides the best available evidence for gravitational radiation. Accretion disks and jets observed in close binaries offer a very good testing ground for models of active galactic nuclei and quasars.

  20. Binary stars.

    PubMed

    Paczynacuteski, B

    1984-07-20

    Most stars in the solar neighborhood are either double or multiple systems. They provide a unique opportunity to measure stellar masses and radii and to study many interesting and important phenomena. The best candidates for black holes are compact massive components of two x-ray binaries: Cygnus X-1 and LMC X-3. The binary radio pulsar PSR 1913 + 16 provides the best available evidence for gravitational radiation. Accretion disks and jets observed in close binaries offer a very good testing ground for models of active galactic nuclei and quasars. PMID:17749544

  1. Improved capacitive EKG electrode

    NASA Technical Reports Server (NTRS)

    Day, J. L.; Griffith, M. E.; Portnox, W. M.; Stotts, L. J.

    1979-01-01

    Light, compact electrode monitors heart signals through burn ointment and requires no electrolyte paste for coupling to skin. Innovation is useful because of its ability to monitor heart condition of burn victims.

  2. Capacitive deionization system

    SciTech Connect

    Richardson, J. H., LLNL

    1996-10-01

    The new capacitive deionization system (CDI) removes ions, contaminants impurities from water and other aqueous process streams, and further selectively places the removed ions back into solution during regeneration. It provides a separation process that does not utilize chemical regeneration processes, and thus significantly reduces or completely eliminates secondary wastes associated with the operation of ion exchange resins. In the CDI, electrolyte flows in open channels formed between adjacent electrodes, and consequently the pressure drop is much lower than conventional separation processes. The fluid flow can be gravity fed through these open channels, and does not require membranes. This feature represents a significant advantage over the conventional reverse osmosis systems which include water permeable cellulose acetate membranes, and over the electrodialysis systems which require expensive and exotic ion exchange membranes. The CDI is adaptable for use in a wide variety of commercial applications, including domestic water softening, industrial water softening, waste water purification, sea water desalination, treatment of nuclear and aqueous wastes, treatment of boiler water in nuclear and fossil power plants, production of high-purity water for semiconductor processing, and removal of salt from water for agricultural irrigation. CDI accomplishes this removal of impurities by a variety of mechanisms, but predominantly by electrostatic removal of organic and inorganic ions from water or any other dielectric solvent.

  3. Motion artifacts in capacitive ECG measurements: reducing the combined effect of DC voltages and capacitance changes using an injection signal.

    PubMed

    Serteyn, A; Vullings, R; Meftah, M; Bergmans, J W M

    2015-01-01

    Capacitive electrodes are a promising alternative to the conventional adhesive electrodes for ECG measurements. They provide more comfort to the patient when integrated in everyday objects (e.g., beds or seats) for long-term monitoring. However, the application of capacitive sensors is limited by their high sensitivity to motion artifacts. For example, motion at the body-electrode interface causes variations of the coupling capacitance which, in the presence of a dc voltage across the coupling capacitor, create strong artifacts in the measurements. The origin, relevance, and reduction of this specific and important type of artifacts are studied here. An injection signal is exploited to track the variations of the coupling capacitance in real time. This information is then used by an identification scheme to estimate the artifacts and subtract them from the measurements. The method was evaluated in simulations, lab environments, and in a real-life recording on an adult's chest. For the type of artifact under study, a strong artifact reduction ranging from 40 dB for simulated data to 9 dB for a given real-life recording was achieved. The proposed method is automated, does not require any knowledge about the measurement system parameters, and provides an online estimate for the dc voltage across the coupling capacitor.

  4. Oscillation of Capacitance inside Nanopores

    SciTech Connect

    Jiang, De-en; Jin, Zhehui; Wu, Jianzhong

    2011-10-26

    Porous carbons of high surface area are promising as cost-effective electrode materials for supercapacitors. Although great attention has been given to the anomalous increase of the capacitance as the pore size approaches the ionic dimensions, there remains a lack of full comprehension of the size dependence of the capacitance in nanopores. Here we predict from a classical density functional theory that the capacitance of an ionic-liquid electrolyte inside a nanopore oscillates with a decaying envelope as the pore size increases. The oscillatory behavior can be attributed to the interference of the overlapping electric double layers (EDLs); namely, the maxima in capacitance appear when superposition of the two EDLs is most constructive. The theoretical prediction agrees well with the experiment when the pore size is less than twice the ionic diameter. Confirmation of the entire oscillatory spectrum invites future experiments with a precise control of the pore size from micro- to mesoscales.

  5. Oscillation of Capacitance inside Nanopores

    SciTech Connect

    Jiang, Deen; Wu, Jianzhong; Jin, Zhehui

    2011-01-01

    materials for supercapacitors. Although great attention has been given to the anomalous increase of the capacitance as the pore size approaches the ionic dimensions, there remains a lack of full comprehension of the size dependence of the capacitance in nanopores. Here we predict from a classical density functional theory that the capacitance of an ionic-liquid electrolyte inside a nanopore oscillates with a decaying envelope as the pore size increases. The oscillatory behavior can be attributed to the interference of the overlapping electric double layers (EDLs); namely, the maxima in capacitance appear when superposition of the two EDLs is most constructive. The theoretical prediction agreeswell with the experiment when the pore size is less than twice the ionic diameter.Confirmation of the entire oscillatory spectruminvites future experiments with a precise control of the pore size from micro- to mesoscales.

  6. Capacitive Position Sensor For Accelerometer

    NASA Technical Reports Server (NTRS)

    Vanzandt, Thomas R.; Kaiser, William J.; Kenny, Thomas W.

    1995-01-01

    Capacitive position sensor measures displacement of proof mass in prototype accelerometer described in "Single-Crystal Springs for Accelerometers" (NPO-18795). Sensor is ultrasensitive, miniature device operating at ultra-high frequency and described in more detail in "Ultra-High-Frequency Capacitive Displacement Sensor," (NPO-18675). Advances in design and fabrication of prototype accelerometer also applicable to magnetometers and other sensors in which sensed quantities measured in terms of deflections of small springs.

  7. Josephson effect in low-capacitance superconductor--normal-metal--superconductor systems

    SciTech Connect

    Bauernschmitt, R.; Siewert, J.; Nazarov, Y.V.; Odintsov, A.A. )

    1994-02-01

    The transport properties of a small superconductor--normal-metal--superconducting tunnel junction can be controlled by a gate electrode coupled capacitively to the central island. We evaluate the critical Josephson current [ital I][sub [ital c

  8. A capacitive electrode with fast recovery feature.

    PubMed

    Spinelli, Enrique; Haberman, Marcelo; García, Pablo; Guerrero, Federico

    2012-08-01

    Capacitive electrodes (CEs) allow for acquiring biopotentials without galvanic contact, avoiding skin preparation and the use of electrolytic gel. The signal quality provided by present CEs is similar to that of standard wet electrodes, but they are more sensitive to electrostatic charge interference and motion artifacts, mainly when biopotentials are picked up through clothing and coupling capacitances are reduced to tens of picofarads. When artifacts are large enough to saturate the preamplifier, several seconds (up to tens) are needed to recover a proper baseline level, and during this period biopotential signals are irremediably lost. To reduce this problem, a CE that includes a fast-recovery (FR) circuit is proposed. It works directly on the coupling capacitor, recovering the amplifier from saturation while preserving ultra-high input impedance, as a CE requires. A prototype was built and tested acquiring ECG signals. Several experimental data are presented, which show that the proposed circuit significantly reduces record segment losses due to amplifier saturation when working in real environments.

  9. Authentication of Nigella sativa Seed Oil in Binary and Ternary Mixtures with Corn Oil and Soybean Oil Using FTIR Spectroscopy Coupled with Partial Least Square

    PubMed Central

    Rohman, Abdul

    2013-01-01

    Fourier transform infrared spectroscopy (FTIR) combined with multivariate calibration of partial least square (PLS) was developed and optimized for the analysis of Nigella seed oil (NSO) in binary and ternary mixtures with corn oil (CO) and soybean oil (SO). Based on PLS modeling performed, quantitative analysis of NSO in binary mixtures with CO carried out using the second derivative FTIR spectra at combined frequencies of 2977–3028, 1666–1739, and 740–1446 cm−1 revealed the highest value of coefficient of determination (R2, 0.9984) and the lowest value of root mean square error of calibration (RMSEC, 1.34% v/v). NSO in binary mixtures with SO is successfully determined at the combined frequencies of 2985–3024 and 752–1755 cm−1 using the first derivative FTIR spectra with R2 and RMSEC values of 0.9970 and 0.47% v/v, respectively. Meanwhile, the second derivative FTIR spectra at the combined frequencies of 2977–3028 cm−1, 1666–1739 cm−1, and 740–1446 cm−1 were selected for quantitative analysis of NSO in ternary mixture with CO and SO with R2 and RMSEC values of 0.9993 and 0.86% v/v, respectively. The results showed that FTIR spectrophotometry is an accurate technique for the quantitative analysis of NSO in binary and ternary mixtures with CO and SO. PMID:24319381

  10. Double-driven shield capacitive type proximity sensor

    NASA Technical Reports Server (NTRS)

    Vranish, John M. (Inventor)

    1993-01-01

    A capacity type proximity sensor comprised of a capacitance type sensor, a capacitance type reference, and two independent and mutually opposing driven shields respectively adjacent to the sensor and reference and which are coupled in an electrical bridge circuit configuration and driven by a single frequency crystal controlled oscillator is presented. The bridge circuit additionally includes a pair of fixed electrical impedance elements which form adjacent arms of the bridge and which comprise either a pair of precision resistances or capacitors. Detection of bridge unbalance provides an indication of the mutual proximity between an object and the sensor. Drift compensation is also utilized to improve performance and thus increase sensor range and sensitivity.

  11. Fully Integrated Low-Noise Readout Circuit with Automatic Offset Cancellation Loop for Capacitive Microsensors

    PubMed Central

    Song, Haryong; Park, Yunjong; Kim, Hyungseup; Cho, Dong-il Dan; Ko, Hyoungho

    2015-01-01

    Capacitive sensing schemes are widely used for various microsensors; however, such microsensors suffer from severe parasitic capacitance problems. This paper presents a fully integrated low-noise readout circuit with automatic offset cancellation loop (AOCL) for capacitive microsensors. The output offsets of the capacitive sensing chain due to the parasitic capacitances and process variations are automatically removed using AOCL. The AOCL generates electrically equivalent offset capacitance and enables charge-domain fine calibration using a 10-bit R-2R digital-to-analog converter, charge-transfer switches, and a charge-storing capacitor. The AOCL cancels the unwanted offset by binary-search algorithm based on 10-bit successive approximation register (SAR) logic. The chip is implemented using 0.18 μm complementary metal-oxide-semiconductor (CMOS) process with an active area of 1.76 mm2. The power consumption is 220 μW with 3.3 V supply. The input parasitic capacitances within the range of −250 fF to 250 fF can be cancelled out automatically, and the required calibration time is lower than 10 ms. PMID:26473877

  12. Fully integrated low-noise readout circuit with automatic offset cancellation loop for capacitive microsensors.

    PubMed

    Song, Haryong; Park, Yunjong; Kim, Hyungseup; Cho, Dong-Il Dan; Ko, Hyoungho

    2015-10-14

    Capacitive sensing schemes are widely used for various microsensors; however, such microsensors suffer from severe parasitic capacitance problems. This paper presents a fully integrated low-noise readout circuit with automatic offset cancellation loop (AOCL) for capacitive microsensors. The output offsets of the capacitive sensing chain due to the parasitic capacitances and process variations are automatically removed using AOCL. The AOCL generates electrically equivalent offset capacitance and enables charge-domain fine calibration using a 10-bit R-2R digital-to-analog converter, charge-transfer switches, and a charge-storing capacitor. The AOCL cancels the unwanted offset by binary-search algorithm based on 10-bit successive approximation register (SAR) logic. The chip is implemented using 0.18 μm complementary metal-oxide-semiconductor (CMOS) process with an active area of 1.76 mm². The power consumption is 220 μW with 3.3 V supply. The input parasitic capacitances within the range of -250 fF to 250 fF can be cancelled out automatically, and the required calibration time is lower than 10 ms.

  13. Fully integrated low-noise readout circuit with automatic offset cancellation loop for capacitive microsensors.

    PubMed

    Song, Haryong; Park, Yunjong; Kim, Hyungseup; Cho, Dong-Il Dan; Ko, Hyoungho

    2015-01-01

    Capacitive sensing schemes are widely used for various microsensors; however, such microsensors suffer from severe parasitic capacitance problems. This paper presents a fully integrated low-noise readout circuit with automatic offset cancellation loop (AOCL) for capacitive microsensors. The output offsets of the capacitive sensing chain due to the parasitic capacitances and process variations are automatically removed using AOCL. The AOCL generates electrically equivalent offset capacitance and enables charge-domain fine calibration using a 10-bit R-2R digital-to-analog converter, charge-transfer switches, and a charge-storing capacitor. The AOCL cancels the unwanted offset by binary-search algorithm based on 10-bit successive approximation register (SAR) logic. The chip is implemented using 0.18 μm complementary metal-oxide-semiconductor (CMOS) process with an active area of 1.76 mm². The power consumption is 220 μW with 3.3 V supply. The input parasitic capacitances within the range of -250 fF to 250 fF can be cancelled out automatically, and the required calibration time is lower than 10 ms. PMID:26473877

  14. Improved resistive shunt by means of negative capacitance: new circuit, performances and multi-mode control

    NASA Astrophysics Data System (ADS)

    Berardengo, M.; Thomas, O.; Giraud-Audine, C.; Manzoni, S.

    2016-07-01

    This paper deals with vibration control by means of piezoelectric patches shunted with electrical impedances made up by a resistance and a negative capacitance. The paper analyses most of the possible layouts by which a negative capacitance can be built and shows that a common mathematical description is possible. This allows closed formulations to be found in order to optimise the electrical network for mono- and multi-mode control. General analytical formulations are obtained to estimate the performance of the shunt in terms of vibration reduction. In particular, it is highlighted that the main effect of a negative capacitance is to artificially enhance the electromechanical coupling factor, which is the basis of performance estimation. Stability issues relating to the use of negative capacitances are especially addressed using refined models for the piezoelectric patch capacitance. Furthermore, a new circuit based on a couple of negative capacitances is proposed and tested, showing better performances than those provided by the usual layouts with a single negative capacitance. Finally, guidelines and analytical formulations to deal with the practical implementation of negative capacitance circuits are provided.

  15. Tracking cancer cell proliferation on a CMOS capacitance sensor chip.

    PubMed

    Prakash, Somashekar Bangalore; Abshire, Pamela

    2008-05-15

    We report a novel technique for assessing cell proliferation that employs integrated capacitance sensors for monitoring the growth of anchorage-dependent living cells. The sensors measure substrate coupling capacitances of cells cultured on-chip in a standard in vitro environment. The biophysical phenomenon underlying the capacitive behavior of cells is the counterionic polarization around the insulating cell bodies when exposed to weak, low frequency electric fields. The sensors employ charge sharing for mapping sensed capacitance values in the fF range to output voltage signals. The sensor chip has been fabricated in a commercially available 0.5microm, 2-poly 3-metal CMOS technology. We report experimental results demonstrating sensor response to the adhesion of MDA-MB-231 breast cancer cells followed by their proliferation on the chip surface. On-chip capacitance sensing offers a non-invasive, label-free, easy-to-use, miniaturized technique with real-time monitoring capability for tracking cell proliferation in vitro. PMID:18281207

  16. Equivalence of ADM Hamiltonian and Effective Field Theory approaches at next-to-next-to-leading order spin1-spin2 coupling of binary inspirals

    SciTech Connect

    Levi, Michele; Steinhoff, Jan E-mail: jan.steinhoff@ist.utl.pt

    2014-12-01

    The next-to-next-to-leading order spin1-spin2 potential for an inspiralling binary, that is essential for accuracy to fourth post-Newtonian order, if both components in the binary are spinning rapidly, has been recently derived independently via the ADM Hamiltonian and the Effective Field Theory approaches, using different gauges and variables. Here we show the complete physical equivalence of the two results, thereby we first prove the equivalence of the ADM Hamiltonian and the Effective Field Theory approaches at next-to-next-to-leading order with the inclusion of spins. The main difficulty in the spinning sectors, which also prescribes the manner in which the comparison of the two results is tackled here, is the existence of redundant unphysical spin degrees of freedom, associated with the spin gauge choice of a point within the extended spinning object for its representative worldline. After gauge fixing and eliminating the unphysical degrees of freedom of the spin and its conjugate at the level of the action, we arrive at curved spacetime generalizations of the Newton-Wigner variables in closed form, which can also be used to obtain further Hamiltonians, based on an Effective Field Theory formulation and computation. Finally, we make use of our validated result to provide gauge invariant relations among the binding energy, angular momentum, and orbital frequency of an inspiralling binary with generic compact spinning components to fourth post-Newtonian order, including all known sectors up to date.

  17. Binary Planets

    NASA Astrophysics Data System (ADS)

    Ryan, Keegan; Nakajima, Miki; Stevenson, David J.

    2014-11-01

    Can a bound pair of similar mass terrestrial planets exist? We are interested here in bodies with a mass ratio of ~ 3:1 or less (so Pluto/Charon or Earth/Moon do not qualify) and we do not regard the absence of any such discoveries in the Kepler data set to be significant since the tidal decay and merger of a close binary is prohibitively fast well inside of 1AU. SPH simulations of equal mass “Earths” were carried out to seek an answer to this question, assuming encounters that were only slightly more energetic than parabolic (zero energy). We were interested in whether the collision or near collision of two similar mass bodies would lead to a binary in which the two bodies remain largely intact, effectively a tidal capture hypothesis though with the tidal distortion being very large. Necessarily, the angular momentum of such an encounter will lead to bodies separated by only a few planetary radii if capture occurs. Consistent with previous work, mostly by Canup, we find that most impacts are disruptive, leading to a dominant mass body surrounded by a disk from which a secondary forms whose mass is small compared to the primary, hence not a binary planet by our adopted definition. However, larger impact parameter “kissing” collisions were found to produce binaries because the dissipation upon first encounter was sufficient to provide a bound orbit that was then rung down by tides to an end state where the planets are only a few planetary radii apart. The long computational times for these simulation make it difficult to fully map the phase space of encounters for which this outcome is likely but the indications are that the probability is not vanishingly small and since planetary encounters are a plausible part of planet formation, we expect binary planets to exist and be a non-negligible fraction of the larger orbital radius exoplanets awaiting discovery.

  18. The Capacitive Magnetic Field Sensor

    NASA Astrophysics Data System (ADS)

    Zyatkov, D. O.; Yurchenko, A. V.; Balashov, V. B.; Yurchenko, V. I.

    2016-01-01

    The results of a study of sensitive element magnetic field sensor are represented in this paper. The sensor is based on the change of the capacitance with an active dielectric (ferrofluid) due to the magnitude of magnetic field. To prepare the ferrofluid magnetic particles are used, which have a followingdispersion equal to 50 < Ø < 56, 45 < Ø < 50, 40 < Ø < 45 and Ø < 40micron of nanocrystalline alloy of brand 5BDSR. The dependence of the sensitivity of the capacitive element from the ferrofluid with different dispersion of magnetic particles is considered. The threshold of sensitivity and sensitivity of a measuring cell with ferrofluid by a magnetic field was determined. The experimental graphs of capacitance change of the magnitude of magnetic field are presented.

  19. Determination of the theoretical capacitance of a concave capacitance sensor.

    PubMed

    Abouelwafa, M S; Kendall, E J

    1979-09-01

    The practical use of four concave capacitance plates for determining in situ volume fractions in two-phase pipelines has been amply demonstrated. In this letter, the system is analyzed theoretically using a microstrip technique and the results are compared with experimental data.

  20. Improving capacitance/damping ratio in a capacitive MEMS transducer

    NASA Astrophysics Data System (ADS)

    Dias, Rosana A.; Rocha, Luis A.

    2014-01-01

    Damping forces play an important role in capacitive MEMS (microelectromechanical systems) behavior, and typical damper design (parallel-plates) cannot address the design conflict between increase in electrical capacitance and damping reduction. Squeeze-film damping in in-plane parallel-plate MEMS is discussed here and a novel damper geometry for gap-varying parallel-plates is introduced and used to increase the capacitance/damping ratio. The new geometry is compared with a typical parallel-plate design for an silicon-on-insulator process (25 µm thick) and experimental data shows an approximate 25% to 50% reduction for the damping coefficient in structures with 500 µm long dampers (for a gap variation between 0.75 and 3.75 µm), in agreement with computational fluid dynamics simulations, without significantly affecting the capacitance value (∼4% reduction). Preliminary simulations to study the role of the different geometric parameters involved in the improved geometry are also performed and reveal that the channel width is the most critical value for effective damping reduction.

  1. Driven shielding capacitive proximity sensor

    NASA Technical Reports Server (NTRS)

    Vranish, John M. (Inventor); McConnell, Robert L. (Inventor)

    2000-01-01

    A capacitive proximity sensing element, backed by a reflector driven at the same voltage as and in phase with the sensor, is used to reflect the field lines away from a grounded robot arm towards an intruding object, thus dramatically increasing the sensor's range and sensitivity.

  2. The coupling of a disk corona and a jet for the radio/X-ray correlation in black hole X-ray binaries

    NASA Astrophysics Data System (ADS)

    Qiao, Erlin

    2015-08-01

    We interpret the radio/X-ray correlation of LR ∝ LX1.4 for LX/LEdd >10-3 in black hole X-ray binaries with a detailed disk corona-jet model, in which the accretion flow and the jet are connected by a parameter, ‘η’, describing the fraction of the matter in the accretion flow ejected outward to form the jet. We calculate LR and LX at different mass accretion rates, adjusting η to fit the observed radio/X-ray correlation of the black hole X-ray transient H1743-322 for LX/LEdd > 10-3. It is found that the value of η for this radio/X-ray correlation for LX/LEdd > 10-3, is systematically less than that of the case for LX/LEdd < 10-3, which is consistent with the general idea that the jet is often relatively suppressed at the high luminosity phase in black hole X-ray binaries.

  3. Design of auto-tuning capacitive power transfer system for wireless power transfer

    NASA Astrophysics Data System (ADS)

    Lu, Kai; Kiong Nguang, Sing

    2016-09-01

    This paper presents the design of capacitive wireless power transfer systems based on a Class-E inverter approach. The main reason for adopting the Class-E inverter approach is because of its high efficiency, theoretically 100%. However, the operation of a Class-E inverter is highly sensitive to its circuit's parameters. In a typical capacitive wireless power transfer application, the capacitive coupling distance between plates is subject to changes, and hence its power transfer efficiency is greatly affected if the Class-E inverter is properly tuned. This drawback motivates us to develop an auto frequency tuning algorithm for a Class-E inverter which maintains its power transfer efficiency in spite of the variations of capacitive coupling distances between plates and circuit's parameters. Finally, simulation and experiment are carried out to verify the effectiveness of the auto frequency tuning algorithm.

  4. Radial profile of the electron energy distribution function in RF capacitive gas-discharge plasma

    NASA Astrophysics Data System (ADS)

    Dimitrova, M.; Popov, Tsv; Puac, N.; Skoro, N.; Spasic, K.; Malovic, G.; Dias, F. M.; Petrovic, Z. Lj

    2016-03-01

    This paper reports experimental results on low-pressure argon capacitive RF discharge (parallel-plate capacitively-coupled plasma - CCP) under different conditions, namely, gas pressure in the range 3 -r- 30 Pa and RF power in the range 10 - 100 W. The IV characteristics measured were processed by two different second-derivative probe techniques for determination of the plasma parameters and the electron energy distribution function. The radial profiles of the main plasma parameters are presented.

  5. Actuatable capacitive transducer for quantitative nanoindentation combined with transmission electron microscopy

    DOEpatents

    Warren, Oden L; Asif, Syed Amanula Syed; Cyrankowski, Edward; Kounev, Kalin

    2013-06-04

    An actuatable capacitive transducer including a transducer body, a first capacitor including a displaceable electrode and electrically configured as an electrostatic actuator, and a second capacitor including a displaceable electrode and electrically configured as a capacitive displacement sensor, wherein the second capacitor comprises a multi-plate capacitor. The actuatable capacitive transducer further includes a coupling shaft configured to mechanically couple the displaceable electrode of the first capacitor to the displaceable electrode of the second capacitor to form a displaceable electrode unit which is displaceable relative to the transducer body, and an electrically-conductive indenter mechanically coupled to the coupling shaft so as to be displaceable in unison with the displaceable electrode unit.

  6. Actuatable capacitive transducer for quantitative nanoindentation combined with transmission electron microscopy

    DOEpatents

    Warren, Oden L.; Asif, S. A. Syed; Cyrankowski, Edward; Kounev, Kalin

    2010-09-21

    An actuatable capacitive transducer including a transducer body, a first capacitor including a displaceable electrode and electrically configured as an electrostatic actuator, and a second capacitor including a displaceable electrode and electrically configured as a capacitive displacement sensor, wherein the second capacitor comprises a multi-plate capacitor. The actuatable capacitive transducer further includes a coupling shaft configured to mechanically couple the displaceable electrode of the first capacitor to the displaceable electrode of the second capacitor to form a displaceable electrode unit which is displaceable relative to the transducer body, and an electrically-conductive indenter mechanically coupled to the coupling shaft so as to be displaceable in unison with the displaceable electrode unit.-

  7. Lightweight linear alternators with and without capacitive tuning

    NASA Technical Reports Server (NTRS)

    Niedra, Janis M.

    1993-01-01

    Permanent magnet excited linear alternators rated tens of kW and coupled to free-piston Stirling engines are presently viewed as promising candidates for long term generation of electric power in both space and terrestrial applications. Series capacitive cancellation of the internal inductive reactance of such alternators was considered a viable way to both increase power extraction and to suppress unstable modes of the thermodynamic oscillation. Idealized toroidal and cylindrical alternator geometries are used for a comparative study of the issues of specific mass and capacitive tuning, subject to stability criteria. The analysis shows that the stator mass of an alternator designed to be capacitively tuned is always greater than the minimum achievable stator mass of an alternator designed with no capacitors, assuming equal utilization of materials ratings and the same frequency and power to a resistive load. This conclusion is not substantially altered when the usually lesser masses of the magnets and of any capacitors are added. Within the reported stability requirements and under circumstances of normal materials ratings, this study finds no clear advantage to capacitive tuning. Comparative plots of the various constituent masses are presented versus the internal power factor taken as a design degree of freedom. The explicit formulas developed for stator core, coil, capacitor, and magnet masses and for the degree of magnet utilization provide useful estimates of scaling effects.

  8. Quantum capacitance in topological insulators.

    PubMed

    Xiu, Faxian; Meyer, Nicholas; Kou, Xufeng; He, Liang; Lang, Murong; Wang, Yong; Yu, Xinxin; Fedorov, Alexei V; Zou, Jin; Wang, Kang L

    2012-01-01

    Topological insulators show unique properties resulting from massless, Dirac-like surface states that are protected by time-reversal symmetry. Theory predicts that the surface states exhibit a quantum spin Hall effect with counter-propagating electrons carrying opposite spins in the absence of an external magnetic field. However, to date, the revelation of these states through conventional transport measurements remains a significant challenge owing to the predominance of bulk carriers. Here, we report on an experimental observation of Shubnikov-de Haas oscillations in quantum capacitance measurements, which originate from topological helical states. Unlike the traditional transport approach, the quantum capacitance measurements are remarkably alleviated from bulk interference at high excitation frequencies, thus enabling a distinction between the surface and bulk. We also demonstrate easy access to the surface states at relatively high temperatures up to 60 K. Our approach may eventually facilitate an exciting exploration of exotic topological properties at room temperature.

  9. Full-bridge capacitive extensometer

    NASA Astrophysics Data System (ADS)

    Peters, Randall D.

    1993-08-01

    Capacitive transducers have proven to be very effective sensors of small displacements, because of inherent stability and noninvasive high resolution. The most versatile ones have been those of a differential type, in which two elements are altered in opposite directions in response to change of the system parameter being monitored. Oftentimes, this differential pair has been incorporated into a bridge circuit, which is a useful means for employing synchronous detection to improve signal to noise ratios. Unlike previous differential capacitive dilatometers which used only two active capacitors, the present sensor is a full-bridge type, which is well suited to measuring low-level thermal expansions. This analog sensor is capable of 0.1 μm resolution anywhere within a range of several centimeters, with a linearity of 0.1%. Its user friendly output can be put on a strip chart recorder or directed to a computer for sophisticated data analysis.

  10. Capacitive de-ionization electrode

    SciTech Connect

    Daily, III, William D.

    2013-03-19

    An electrode "cell" for use in a capacitive deionization (CDI) reactor consists of the electrode support structure, a non-reactive conductive material, the electrode accompaniment or substrate and a flow through screen/separator. These "layers" are repeated and the electrodes are sealed together with gaskets between two end plates to create stacked sets of alternating anode and cathode electrodes in the CDI reactor.

  11. The coupling of a disk corona and a jet for the radio/X-ray correlation in black hole X-ray binaries

    NASA Astrophysics Data System (ADS)

    Qiao, Erlin

    2016-02-01

    We interpret the radio/X-ray correlation of L R ~ L X ~1.4 for L X/L Edd >~ 10-3 with a detailed disk corona-jet model, in which the accretion flow and the jet are connected by a parameter, η, describing the fraction of the matter in the accretion flow ejected outward to form the jet. We calculate L R and L X at different Ṁ, adjusting η to fit the observed radio/X-ray correlation of the black hole X-ray transient H1743-322 for L X/L Edd > 10-3. It is found that the value of η for this radio/X-ray correlation for L X/L Edd > 10-3, is systematically less than that of the case for L X/L Edd < 10-3, which is consistent with the general idea that the jet is often relatively suppressed at the high luminosity phase in black hole X-ray binaries.

  12. Redox regulation of mammalian sperm capacitation

    PubMed Central

    O’Flaherty, Cristian

    2015-01-01

    Capacitation is a series of morphological and metabolic changes necessary for the spermatozoon to achieve fertilizing ability. One of the earlier happenings during mammalian sperm capacitation is the production of reactive oxygen species (ROS) that will trigger and regulate a series of events including protein phosphorylation, in a time-dependent fashion. The identity of the sperm oxidase responsible for the production of ROS involved in capacitation is still elusive, and several candidates are discussed in this review. Interestingly, ROS-induced ROS formation has been described during human sperm capacitation. Redox signaling during capacitation is associated with changes in thiol groups of proteins located on the plasma membrane and subcellular compartments of the spermatozoon. Both, oxidation of thiols forming disulfide bridges and the increase on thiol content are necessary to regulate different sperm proteins associated with capacitation. Reducing equivalents such as NADH and NADPH are necessary to support capacitation in many species including humans. Lactate dehydrogenase, glucose-6-phospohate dehydrogenase, and isocitrate dehydrogenase are responsible in supplying NAD (P) H for sperm capacitation. Peroxiredoxins (PRDXs) are newly described enzymes with antioxidant properties that can protect mammalian spermatozoa; however, they are also candidates for assuring the regulation of redox signaling required for sperm capacitation. The dysregulation of PRDXs and of enzymes needed for their reactivation such as thioredoxin/thioredoxin reductase system and glutathione-S-transferases impairs sperm motility, capacitation, and promotes DNA damage in spermatozoa leading to male infertility. PMID:25926608

  13. An approach to evaluate capacitance, capacitive reactance and resistance of pivoted pads of a thrust bearing

    NASA Astrophysics Data System (ADS)

    Prashad, Har

    1992-07-01

    A theoretical approach is developed for determining the capacitance and active resistance between the interacting surfaces of pivoted pads and thrust collar, under different conditions of operation. It is shown that resistance and capacitive reactance of a thrust bearing decrease with the number of pads times the values of these parameters for an individual pad, and that capacitance increases with the number of pads times the capacitance of an individual pad. The analysis presented has a potential to diagnose the behavior of pivoted pad thrust bearings with the angle of tilt and the ratio of film thickness at the leading to trailing edge, by determining the variation of capacitance, resistance, and capacitive reactance.

  14. On the interfacial capacitance of an electrolyte at a metallic electrode around zero surface charge

    NASA Astrophysics Data System (ADS)

    Bari Bhuiyan, Lutful; Lamperski, Stanisław

    2013-03-01

    The behaviour of the capacitance of a planar double layer containing a restricted primitive model electrolyte (equi-sized rigid ions moving in a continuum dielectric) at and around zero surface charge is examined for a polarizable electrode with particular emphasis on a metallic surface. Capacitance results are reported for symmetric valency (1:1) salts encompassing a range of concentrations and temperatures covering both electrolyte solution and ionic liquid regimes. Although the modified Poisson-Boltzmann theory is principally employed, at higher concentrations the theoretical calculations have been supplemented by Monte Carlo simulations. Capacitance anomaly, that is, increase of capacitance with temperature at low temperatures, is seen to occur when the electrode is an insulator with a low dielectric constant or when it is unpolarized. No capacitance anomaly is, however, seen for a metallic electrode with an infinite dielectric constant and in this situation the capacitance increases (a) dramatically at low temperatures (strong coupling) at a given concentration, and (b) as concentration increases at a given temperature. These capacitance trends are consistent with earlier works in the presence or absence of surface polarization and, in particular, the results for a conducting electrode at ionic liquid concentrations are consistent with that recently reported by Loth et al. [Phys. Rev. E, 82, 056102 (2010)]. Overall the theoretical predictions are qualitative to semi-quantitative with the simulations.

  15. Capacitance enhancement via electrode patterning

    SciTech Connect

    Ho, Tuan A.; Striolo, Alberto

    2013-11-28

    The necessity of increasing the energy density in electric double layer capacitors to meet current demand is fueling fundamental and applied research alike. We report here molecular dynamics simulation results for aqueous electrolytes near model electrodes. Particular focus is on the effect of electrode patterning on the structure of interfacial electrolytes, and on the potential drop between the solid electrodes and the bulk electrolytes. The latter is estimated by numerically integrating the Poisson equation using the charge densities due to water and ions accumulated near the interface as input. We considered uniform and patterned electrodes, both positively and negatively charged. The uniformly charged electrodes are modeled as graphite. The patterned ones are obtained by removing carbon atoms from the top-most graphene layer, yielding nanoscopic squares and stripes patterns. For simplicity, the patterned electrodes are effectively simulated as insulators (the charge remains localized on the top-most layer of carbon atoms). Our simulations show that the patterns alter the structure of water and the accumulation of ions at the liquid-solid interfaces. Using aqueous NaCl solutions, we found that while the capacitance calculated for three positively charged electrodes did not change much, that calculated for the negatively charged electrodes significantly increased upon patterning. We find that both water structure and orientation, as well as ion accumulation affect the capacitance. As electrode patterning affects differently water structure and ion accumulation, it might be possible to observe ion-specific effects. These results could be useful for advancing our understanding of electric double layer capacitors, capacitive desalination processes, as well as of fundamental interfacial electrolytes properties.

  16. Capacitance enhancement via electrode patterning.

    PubMed

    Ho, Tuan A; Striolo, Alberto

    2013-11-28

    The necessity of increasing the energy density in electric double layer capacitors to meet current demand is fueling fundamental and applied research alike. We report here molecular dynamics simulation results for aqueous electrolytes near model electrodes. Particular focus is on the effect of electrode patterning on the structure of interfacial electrolytes, and on the potential drop between the solid electrodes and the bulk electrolytes. The latter is estimated by numerically integrating the Poisson equation using the charge densities due to water and ions accumulated near the interface as input. We considered uniform and patterned electrodes, both positively and negatively charged. The uniformly charged electrodes are modeled as graphite. The patterned ones are obtained by removing carbon atoms from the top-most graphene layer, yielding nanoscopic squares and stripes patterns. For simplicity, the patterned electrodes are effectively simulated as insulators (the charge remains localized on the top-most layer of carbon atoms). Our simulations show that the patterns alter the structure of water and the accumulation of ions at the liquid-solid interfaces. Using aqueous NaCl solutions, we found that while the capacitance calculated for three positively charged electrodes did not change much, that calculated for the negatively charged electrodes significantly increased upon patterning. We find that both water structure and orientation, as well as ion accumulation affect the capacitance. As electrode patterning affects differently water structure and ion accumulation, it might be possible to observe ion-specific effects. These results could be useful for advancing our understanding of electric double layer capacitors, capacitive desalination processes, as well as of fundamental interfacial electrolytes properties.

  17. Dual Cryogenic Capacitive Density Sensor

    NASA Technical Reports Server (NTRS)

    Youngquist, Robert; Mata, Carlos; Vokrot, Peter; Cox, Robert

    2009-01-01

    A dual cryogenic capacitive density sensor has been developed. The device contains capacitive sensors that monitor two-phase cryogenic flow density to within 1% accuracy, which, if temperature were known, could be used to determine the ratio of liquid to gas in the line. Two of these density sensors, located a known distance apart, comprise the sensor, providing some information on the velocity of the flow. This sensor was constructed as a proposed mass flowmeter with high data acquisition rates. Without moving parts, this device is capable of detecting the density change within a two-phase cryogenic flow more than 100 times a second. Detection is enabled by a series of two sets of five parallel plates with stainless steel, cryogenically rated tubing. The parallel plates form the two capacitive sensors, which are measured by electrically isolated digital electronics. These capacitors monitor the dielectric of the flow essentially the density of the flow and can be used to determine (along with temperature) the ratio of cryogenic liquid to gas. Combining this information with the velocity of the flow can, with care, be used to approximate the total two-phase mass flow. The sensor can be operated at moderately high pressures and can be lowered into a cryogenic bath. The electronics have been substantially improved over the older sensors, incorporating a better microprocessor, elaborate ground loop protection and noise limiting circuitry, and reduced temperature sensitivity. At the time of this writing, this design has been bench tested at room temperature, but actual cryogenic tests are pending

  18. Voltage-dependent capacitance of human embryonic kidney cells

    NASA Astrophysics Data System (ADS)

    Farrell, Brenda; Do Shope, Cythnia; Brownell, William E.

    2006-04-01

    We determine membrane capacitance, C as a function of dc voltage for the human embryonic kidney (HEK) cell. C was calculated from the admittance, Y , obtained during a voltage ramp when the HEK cell was held in whole-cell patch-clamp configuration. Y was determined at frequencies of 390.625 and 781.25Hz from the measured current, i obtained with a dual-sinusoidal stimulus. We find that the fractional increase in the capacitance, C is small (<1%) and grows with the square of the voltage, Ψ . C can be described by: C=C(0)(1+α(Ψ+ψs)2) [where C(0) : Capacitance at 0volts , ψs : Difference in surface potential between cytoplasmic and extracellular leaflets and α : Proportionality constant]. We find that α and ψs are 0.120 (±0.01)V-2 and -0.073 (±0.017)V in solutions that contain ion channel blockers and 0.108 (±0.29)V-2 and -0.023 (±0.009)V when 10mM sodium salicylate was added to the extracellular solution. This suggests that salicylate does not affect the rate at which C grows with Ψ , but reduces the charge asymmetry of the membrane. We also observe an additional linear differential capacitance of about (-46fFV-1) in about 60% of the cells, this additional component acts simultaneously with the quadratic component and was not observed when salicylate was added to the solution. We suggest that the voltage dependent capacitance originates from electromechanical coupling either by electrostriction and/or Maxwell stress effects and estimate that a small electromechanical force (≈1pN) acts at physiological potentials. These results are relevant to understand the electromechanical coupling in outer hair cells (OHCs) of the mammalian cochlea, where an asymmetric bell-shaped C versus Ψ relationship is observed upon application of a similar field. Prestin, a membrane protein expressed in OHCs is required to observe this function. When we compare the total charge contributions from HEK cell membrane ( 7×104 electrons, 10pF cell) with that determined for

  19. Compact monolithic capacitive discharge unit

    DOEpatents

    Roesler, Alexander W.; Vernon, George E.; Hoke, Darren A.; De Marquis, Virginia K.; Harris, Steven M.

    2007-06-26

    A compact monolithic capacitive discharge unit (CDU) is disclosed in which a thyristor switch and a flyback charging circuit are both sandwiched about a ceramic energy storage capacitor. The result is a compact rugged assembly which provides a low-inductance current discharge path. The flyback charging circuit preferably includes a low-temperature co-fired ceramic transformer. The CDU can further include one or more ceramic substrates for enclosing the thyristor switch and for holding various passive components used in the flyback charging circuit. A load such as a detonator can also be attached directly to the CDU.

  20. Non- contacting capacitive diagnostic device

    DOEpatents

    Ellison, Timothy

    2005-07-12

    A non-contacting capacitive diagnostic device includes a pulsed light source for producing an electric field in a semiconductor or photovoltaic device or material to be evaluated and a circuit responsive to the electric field. The circuit is not in physical contact with the device or material being evaluated and produces an electrical signal characteristic of the electric field produced in the device or material. The diagnostic device permits quality control and evaluation of semiconductor or photovoltaic device properties in continuous manufacturing processes.

  1. Phosphoproteome analysis of capacitated human sperm. Evidence of tyrosine phosphorylation of a kinase-anchoring protein 3 and valosin-containing protein/p97 during capacitation.

    PubMed

    Ficarro, Scott; Chertihin, Olga; Westbrook, V Anne; White, Forest; Jayes, Friederike; Kalab, Petr; Marto, Jarrod A; Shabanowitz, Jeffrey; Herr, John C; Hunt, Donald F; Visconti, Pablo E

    2003-03-28

    Before fertilization can occur, mammalian sperm must undergo capacitation, a process that requires a cyclic AMP-dependent increase in tyrosine phosphorylation. To identify proteins phosphorylated during capacitation, two-dimensional gel analysis coupled to anti-phosphotyrosine immunoblots and tandem mass spectrometry (MS/MS) was performed. Among the protein targets, valosin-containing protein (VCP), a homolog of the SNARE-interacting protein NSF, and two members of the A kinase-anchoring protein (AKAP) family were found to be tyrosine phosphorylated during capacitation. In addition, immobilized metal affinity chromatography was used to investigate phosphorylation sites in whole protein digests from capacitated human sperm. To increase this chromatographic selectivity for phosphopeptides, acidic residues in peptide digests were converted to their respective methyl esters before affinity chromatography. More than 60 phosphorylated sequences were then mapped by MS/MS, including precise sites of tyrosine and serine phosphorylation of the sperm tail proteins AKAP-3 and AKAP-4. Moreover, differential isotopic labeling was developed to quantify phosphorylation changes occurring during capacitation. The phosphopeptide enrichment and quantification methodology coupled to MS/MS, described here for the first time, can be employed to map and compare phosphorylation sites involved in multiple cellular processes. Although we were unable to determine the exact site of phosphorylation of VCP, we did confirm, using a cross-immunoprecipitation approach, that this protein is tyrosine phosphorylated during capacitation. Immunolocalization of VCP showed fluorescent staining in the neck of noncapacitated sperm. However, after capacitation, staining in the neck decreased, and most of the sperm showed fluorescent staining in the anterior head.

  2. Module Eleven: Capacitance; Basic Electricity and Electronics Individualized Learning System.

    ERIC Educational Resources Information Center

    Bureau of Naval Personnel, Washington, DC.

    In this module the student will learn about another circuit quantity, capacitance, and discover the effects of this component on circuit current, voltage, and power. The module is divided into seven lessons: the capacitor, theory of capacitance, total capacitance, RC (resistive-capacitive circuit) time constant, capacitive reactance, phase and…

  3. Capacitance Measurement with a Sigma Delta Converter for 3D Electrical Capacitance Tomography

    NASA Technical Reports Server (NTRS)

    Nurge, Mark

    2005-01-01

    This paper will explore suitability of a newly available capacitance to digital converter for use in a 3D Electrical Capacitance Tomography system. A switch design is presented along with circuitry needed to extend the range of the capacitance to digital converter. Results are then discussed for a 15+ hour drift and noise test.

  4. Modeling Binary Neutron Stars

    NASA Astrophysics Data System (ADS)

    Park, Conner; Read, Jocelyn; Flynn, Eric; Lockett-Ruiz, Veronica

    2016-03-01

    Gravitational waves, predicted by Einstein's Theory of Relativity, are a new frontier in astronomical observation we can use to observe phenomena in the universe. Laser Interferometer Gravitational wave Observatory (LIGO) is currently searching for gravitational wave signals, and requires accurate predictions in order to best extract astronomical signals from all other sources of fluctuations. The focus of my research is in increasing the accuracy of Post-Newtonian models of binary neutron star coalescence to match the computationally expensive Numerical models. Numerical simulations can take months to compute a couple of milliseconds of signal whereas the Post-Newtonian can generate similar signals in seconds. However the Post-Newtonian model is an approximation, e.g. the Taylor T4 Post-Newtonian model assumes that the two bodies in the binary neutron star system are point charges. To increase the effectiveness of the approximation, I added in tidal effects, resonance frequencies, and a windowing function. Using these observed effects from simulations significantly increases the Post-Newtonian model's similarity to the Numerical signal.

  5. High Temperature Capacitive Strain Gage

    NASA Technical Reports Server (NTRS)

    Wnuk, Stephen P., Jr.; Wnuk, Stephen P., III; Wnuk, V. P.

    1990-01-01

    Capacitive strain gages designed for measurements in wind tunnels to 2000 F were built and evaluated. Two design approaches were followed. One approach was based on fixed capacitor plates with a movable ground plane inserted between the plates to effect differential capacitive output with strain. The second approach was based on movable capacitor plates suspended between sapphire bearings, housed in a rugged body, and arranged to operate as a differential capacitor. A sapphire bearing gage (1/4 in. diameter x 1 in. in size) was built with a range of 50,000 and a resolution of 200 microstrain. Apparent strain on Rene' 41 was less than + or - 1000 microstrain from room temperature to 2000 F. Three gage models were built from the Ground Plane Differential concept. The first was 1/4 in. square by 1/32 in. high and useable to 700 F. The second was 1/2 in. square by 1/16 in. high and useable to 1440 F. The third, also 1/2 in. square by 1/16 in. high was expected to operate in the 1600 to 2000 F range, but was not tested because time and funding ended.

  6. Ultrahigh Temperature Capacitive Pressure Sensor

    NASA Technical Reports Server (NTRS)

    Harsh, Kevin

    2014-01-01

    Robust, miniaturized sensing systems are needed to improve performance, increase efficiency, and track system health status and failure modes of advanced propulsion systems. Because microsensors must operate in extremely harsh environments, there are many technical challenges involved in developing reliable systems. In addition to high temperatures and pressures, sensing systems are exposed to oxidation, corrosion, thermal shock, fatigue, fouling, and abrasive wear. In these harsh conditions, sensors must be able to withstand high flow rates, vibration, jet fuel, and exhaust. In order for existing and future aeropropulsion turbine engines to improve safety and reduce cost and emissions while controlling engine instabilities, more accurate and complete sensor information is necessary. High-temperature (300 to 1,350 C) capacitive pressure sensors are of particular interest due to their high measurement bandwidth and inherent suitability for wireless readout schemes. The objective of this project is to develop a capacitive pressure sensor based on silicon carbon nitride (SiCN), a new class of high-temperature ceramic materials, which possesses excellent mechanical and electric properties at temperatures up to 1,600 C.

  7. Capacitance densitometer for flow regime identification

    DOEpatents

    Shipp, Jr., Roy L.

    1978-01-01

    This invention relates to a capacitance densitometer for determining the flow regime of a two-phase flow system. A two-element capacitance densitometer is used in conjunction with a conventional single-beam gamma densitometer to unambiguously identify the prevailing flow regime and the average density of a flowing fluid.

  8. The capacitive division image readout: a novel imaging device for microchannel plate detectors

    NASA Astrophysics Data System (ADS)

    Lapington, J. S.; Conneely, T. M.; Leach, S. A.; Moore, L.

    2013-09-01

    The Capacitive Division Image Readout (C-DIR) is a simple and novel image readout for photon counting detectors offering major performance advantages. C-DIR is a charge centroiding device comprising three elements; (i) a resistive anode providing event charge localization, event current return path and electrical isolation from detector high voltage, (ii) a dielectric substrate which capacitively couples the event transient signal to the third element, (iii) the readout device; an array of capacitively coupled electrodes which divides the signal among the readout charge measurement nodes. The resistive anode and dielectric substrate constitute the rear interface of the detector and capacitively couple the signal to the external C-DIR readout device. The C-DIR device is a passive, multilayer printed circuit board type device comprising a matrix of isolated electrodes whose geometries define the capacitive network. C-DIR is manufactured using conventional PCB geometries and is straightforward and economical to construct. C-DIR's robustness and simplicity belie its performance advantages. Its capacitive nature avoids partition noise, the Poisson noise associated with collection of discrete charges. The dominant noise limiting position resolution is electronic noise. However C-DIR also presents a low input capacitance to the readout electronics, minimising this noise component thus maximising spatial resolution. Optimisation of the C-DIR pattern-edge geometry can provide ~90% linear dynamic range. We present data showing image resolution and linearity of the C-DIR device in a microchannel plate detector and describe various electronic charge measurement scheme designed to exploit the full performance potential of the C-DIR device.

  9. Scanning capacitance microscopy for thin film measurements

    NASA Astrophysics Data System (ADS)

    Lee, D. T.; Pelz, J. P.; Bhushan, Bharat

    2006-03-01

    We have used direct, low-frequency scanning capacitance microscopy measurements to characterize variations in thin, dielectric films with up to 1 nm thickness and ~200 nm lateral resolution. This technique may be used on metallic as well as semiconducting substrates because it does not rely upon d C/d V measurements. We also find that the sensitivity of capacitance to film thickness can be enhanced by an aqueous meniscus that typically forms between the atomic force microscope tip and the sample surface. Further, we quantified the nanometre-scale capacitance of the tip-meniscus-sample system that is sensitive to variations in film thickness by making simultaneous capacitance and cantilever deflection measurements. This capacitance is used along with an average film thickness to quantify variations in film thickness.

  10. 3D Alignment of nanowriters using fringe capacitance

    NASA Astrophysics Data System (ADS)

    Lally, Richard; Stark, Thomas; Reeves, Jeremy; Barrett, Lawrence; Bishop, David

    With the introduction of atomic calligraphy, high resolution nanoscale structures can be fabricated rapidly over a large surface area. This reliable, chemically stable and cost effective nanoscale writing method can be applied to a number of interesting applications. One specific application of this writing approach is to fabricate metamaterials, a process that requires precise alignment of the MEMS and substrate. Here we present a MEMS based solution coupling the well-studied comb drive capacitance effects with the less predictable close order fringe effects. The combined capacitance allows for precise measurements in the nanometer range. Using two sets of orthogonal static MEMS comb drives, the capacitance is used to discern the x, y, and z spatial displacement from the substrate. The unique SOI wafer is prepared creating a periodic array of silicon pillars. Placement of additional MEMS comb drives at the MEMS device edges will allow stage corrections for tip, tilt and rotational alignment thereby reducing the effects generated by variations in wafer thickness and surface smoothness. This work is funded by the DARPA A2P Program.

  11. Langmuir probe characterization of capacitively driven discharges in different gases.

    NASA Astrophysics Data System (ADS)

    McFarland, J.; Mahony, C. M. O.; Steen, P. G.; Graham, W. G.

    1997-10-01

    A compensated Langmuir probe technique has been used to study and contrast the plasma parameters of 13.56 MHz capacitively driven discharges operating in H_2, D_2, He and Ar. The discharge was created in a GEC reference reactor configured in the asymmetric capacitive mode. Standard GEC I(V) measurement techniques were used to characterize the energy input. In all gases the form of the electron energy distribution function (EEDF) was found to be dependent on the operating power and pressure and in a manner which was consistent with those previously reported in other capacitively coupled systems (V.A. Godyak, R.B. Piejak and B.M. Alexandrovich, Plasma Sources Sci. Technol., 1 p 36-58 (1992)). In Ar the electron densities, mean energies and plasma potentials were gratifyingly close to those measured in the University of Texas GEC reference reactor (L.J. Overzet and F.Y. Leong-Rousey, Private communication). For input powers between 10 and 100 watts and pressures in the range 75 mTorr to 1000 mTorr the electron densities were between 5 x 10^8 and 9 x 10^10 cm-3 with the highest density in Ar and the lowest in D_2. Mean electron energies were between 2-4 eV. A detailed discussion of the variation between the different gases will be presented.

  12. DNA Nucleotides Detection via capacitance properties of Graphene

    NASA Astrophysics Data System (ADS)

    Khadempar, Nahid; Berahman, Masoud; Yazdanpanah, Arash

    2016-05-01

    In the present paper a new method is suggested to detect the DNA nucleotides on a first-principles calculation of the electronic features of DNA bases which chemisorbed to a graphene sheet placed between two gold electrodes in a contact-channel-contact system. The capacitance properties of graphene in the channel are surveyed using non-equilibrium Green's function coupled with the Density Functional Theory. Thus, the capacitance properties of graphene are theoretically investigated in a biological environment, and, using a novel method, the effect of the chemisorbed DNA nucleotides on electrical charges on the surface of graphene is deciphered. Several parameters in this method are also extracted including Electrostatic energy, Induced density, induced electrostatic potential, Electron difference potential and Electron difference density. The qualitative and quantitative differences among these parameters can be used to identify DNA nucleotides. Some of the advantages of this approach include its ease and high accuracy. What distinguishes the current research is that it is the first experiment to investigate the capacitance properties of gaphene changes in the biological environment and the effect of chemisorbed DNA nucleotides on the surface of graphene on the charge.

  13. Observation of the quantum capacitance in a Cooper-pair transistor

    NASA Astrophysics Data System (ADS)

    Duty, Tim

    2005-03-01

    The effective capacitance of a single Cooper-pair box (SCB) can be defined as the second derivative of its energy with respect to gate voltage. This capacitance has two parts, the geometric capacitance, Cgeom, and the quantum capacitance, CQ. CQ is due to the anti-level crossing caused by the Josephson coupling energy EJ, and depends parametrically on the gate voltage. This capacitance, which is dual to the Josephson inductance, can be substantially larger than Cgeom as well as negative. To detect CQ, we have measured the in- phase and out-of-phase rf-signal reflected from a Cooper-pair transistor (CPT), embedded in a resonant circuit. Under suitable biasing conditions the CPT acts as a SCB in series with a capacitance. It can be shown that the imaginary part of the reflected signal depends linearly on CQ, and we can thus measure CQ directly from the reflected signal as a function of the gate voltage. The measured data agrees well with the theoretical prediction assuming that the system is in the ground state. We can extract the ratio EJ/EC for each of the two junctions in the CPT, where EC is the charging energy of the CPT.

  14. Stability of binaries. Part 1: Rigid binaries

    NASA Astrophysics Data System (ADS)

    Sharma, Ishan

    2015-09-01

    We consider the stability of binary asteroids whose members are possibly granular aggregates held together by self-gravity alone. A binary is said to be stable whenever each member is orbitally and structurally stable to both orbital and structural perturbations. To this end, we extend the stability test for rotating granular aggregates introduced by Sharma (Sharma, I. [2012]. J. Fluid Mech., 708, 71-99; Sharma, I. [2013]. Icarus, 223, 367-382; Sharma, I. [2014]. Icarus, 229, 278-294) to the case of binary systems comprised of rubble members. In part I, we specialize to the case of a binary with rigid members subjected to full three-dimensional perturbations. Finally, we employ the stability test to critically appraise shape models of four suspected binary systems, viz., 216 Kleopatra, 25143 Itokawa, 624 Hektor and 90 Antiope.

  15. Reducing the capacitance of piezoelectric film sensors.

    PubMed

    González, Martín G; Sorichetti, Patricio A; Santiago, Guillermo D

    2016-04-01

    We present a novel design for large area, wideband, polymer piezoelectric sensor with low capacitance. The large area allows better spatial resolution in applications such as photoacoustic tomography and the reduced capacitance eases the design of fast transimpedance amplifiers. The metalized piezoelectric polymer thin film is segmented into N sections, electrically connected in series. In this way, the total capacitance is reduced by a factor 1/N(2), whereas the mechanical response and the active area of the sensor are not modified. We show the construction details for a two-section sensor, together with the impedance spectroscopy and impulse response experimental results that validate the design.

  16. Reducing the capacitance of piezoelectric film sensors.

    PubMed

    González, Martín G; Sorichetti, Patricio A; Santiago, Guillermo D

    2016-04-01

    We present a novel design for large area, wideband, polymer piezoelectric sensor with low capacitance. The large area allows better spatial resolution in applications such as photoacoustic tomography and the reduced capacitance eases the design of fast transimpedance amplifiers. The metalized piezoelectric polymer thin film is segmented into N sections, electrically connected in series. In this way, the total capacitance is reduced by a factor 1/N(2), whereas the mechanical response and the active area of the sensor are not modified. We show the construction details for a two-section sensor, together with the impedance spectroscopy and impulse response experimental results that validate the design. PMID:27131698

  17. Reducing the capacitance of piezoelectric film sensors

    NASA Astrophysics Data System (ADS)

    González, Martín G.; Sorichetti, Patricio A.; Santiago, Guillermo D.

    2016-04-01

    We present a novel design for large area, wideband, polymer piezoelectric sensor with low capacitance. The large area allows better spatial resolution in applications such as photoacoustic tomography and the reduced capacitance eases the design of fast transimpedance amplifiers. The metalized piezoelectric polymer thin film is segmented into N sections, electrically connected in series. In this way, the total capacitance is reduced by a factor 1/N2, whereas the mechanical response and the active area of the sensor are not modified. We show the construction details for a two-section sensor, together with the impedance spectroscopy and impulse response experimental results that validate the design.

  18. Binary Inspiral in Quadratic Gravity

    NASA Astrophysics Data System (ADS)

    Yagi, Kent

    2015-01-01

    Quadratic gravity is a general class of quantum-gravity-inspired theories, where the Einstein-Hilbert action is extended through the addition of all terms quadratic in the curvature tensor coupled to a scalar field. In this article, we focus on the scalar Gauss- Bonnet (sGB) theory and consider the black hole binary inspiral in this theory. By applying the post-Newtonian (PN) formalism, we found that there is a scalar dipole radiation which leads to -1PN correction in the energy flux relative to gravitational radiation in general relativity. From the orbital decay rate of a low-mass X-ray binary A0600-20, we obtain the bound that is six orders of magnitude stronger than the current solar system bound. Furthermore, we show that the excess in the orbital decay rate of XTE J1118+480 can be explained by the scalar radiation in sGB theory.

  19. Binary mask programmable hologram.

    PubMed

    Tsang, P W M; Poon, T-C; Zhou, Changhe; Cheung, K W K

    2012-11-19

    We report, for the first time, the concept and generation of a novel Fresnel hologram called the digital binary mask programmable hologram (BMPH). A BMPH is comprised of a static, high resolution binary grating that is overlaid with a lower resolution binary mask. The reconstructed image of the BMPH can be programmed to approximate a target image (including both intensity and depth information) by configuring the pattern of the binary mask with a simple genetic algorithm (SGA). As the low resolution binary mask can be realized with less stringent display technology, our method enables the development of simple and economical holographic video display.

  20. Three-terminal capacitance cell for stopped-flow measurements of very dilute solutions

    NASA Astrophysics Data System (ADS)

    Tjahjono, Martin; Davis, Thomas; Garland, Marc

    2007-02-01

    A capacitance cell has been designed, constructed, and tested for stopped-flow measurements of very dilute low-relative permittivity liquid solutions. The capacitance cell utilizes a three-terminal design and is connected to ultrahigh sensitivity capacitance bridge. The cell was designed for operating conditions T ≈243.15-373.15K and P ≈0-1MPa and tested with pure anhydrous cyclohexane and with dilute acetone/cyclohexane solutions at 298.15K and 0.1MPa under an argon blanket in a thermostated bath with a temperature variation of <0.001K. Details of the design and materials of construction are reported. The measured relative permittivity of cyclohexane was 2.015 565, in agreement with the literature, and the long term variation of the measurement was ±5×10-6. The relative permittivities of the acetone/cyclohexane solutions were very linear (R2=0.9997) in the measured interval of 0.001-0.008mole fraction. These measurements confirm that the design specifications for stability and resolution/sensitivity of better than 1×10-5 have been realized. Finally, the present online capacitance cell was connected online to an ultrasensitive densitometer and ultrasensitive refractometer and binary acetone/cyclohexane solutions were measured. The measurements of density, refractive index, and relative permittivity were combined to provide a dipole moment of acetone of 2.750±0.005D, which is in good agreement with literature.

  1. Capacitive Cells for Dielectric Constant Measurement

    ERIC Educational Resources Information Center

    Aguilar, Horacio Munguía; Maldonado, Rigoberto Franco

    2015-01-01

    A simple capacitive cell for dielectric constant measurement in liquids is presented. As an illustrative application, the cell is used for measuring the degradation of overheated edible oil through the evaluation of their dielectric constant.

  2. The skin landscape following nonoptical capacitance imaging.

    PubMed

    Xhauflaire-Uhoda, Emmanuelle; Piérard, Gérald E; Quatresooz, Pascale

    2010-01-01

    Skin capacitance is an electrical property measurable at the level of the stratum corneum. Values are related to the moisture content of the tissue. Using the silicon image sensor technology, it has recently become possible to measure capacitance at 50 microm intervals on the skin surface. The resulting nonoptical picture corresponds to skin capacitance imaging. This novel tool for dermatologists highlights with precision the hollow skin surface patterns, including dermatoglyphics, the patterns of the shallow skin lines, and wrinkles. The topographic heterogeneity in skin surface hydration is made visible. In addition, the sweat gland and follicular openings are disclosed. Skin disorders induced by surfactants or presenting as hyperkeratotic areas, including some neoplasms, may show typical aspects. It is concluded that skin capacitance imaging brings added value to the clinical assessment performed by dermatologists. PMID:20141229

  3. Interconnection capacitance models for VLSI circuits

    NASA Astrophysics Data System (ADS)

    Wong, Shyh-Chyi; Liu, Patrick S.; Ru, Jien-Wen; Lin, Shi-Tron

    1998-06-01

    A new set of capacitance models is developed for delay estimation of VLSI interconnections. The set of models is derived for five representative wiring structures, with their combinations covering arbitrary VLSI layouts. A semi-empirical approach is adopted to deal with complicated geometry nature in VLSI and to allow for closed-form capacitance formulas to be developed to provide direct observation of capacitance variation vs process parameters as well as computational efficiency for circuit simulation. The formulas are given explicitly in terms of wire width, wire thickness, dielectric thickness and inter-wire spacing. The models show good agreement with numerical solutions from RAPHAEL and measurement data of fabricated capacitance test structures. The models are further applied and validated on a ring oscillator. It is shown that the frequency of the ring oscillator obtained from HSPICE simulation with our models agrees well with the bench measurement.

  4. High-temperature capacitive strain measurement system

    NASA Technical Reports Server (NTRS)

    Wilson, E. J.; Egger, R. L.

    1975-01-01

    Capacitive strain gage and signal conditioning system measures stress-induced strain and cancels thermal expansion strain at temperatures to 1,500 F (815 C). Gage does not significantly restrain or reinforce specimen.

  5. Search for Binary Trojans

    NASA Astrophysics Data System (ADS)

    Noll, Keith S.; Grundy, W. M.; Ryan, E. L.; Benecchi, S. D.

    2015-11-01

    We have reexamined 41 Trojan asteroids observed with the Hubble Space Telescope (HST) to search for unresolved binaries. We have identified one candidate binary with a separation of 53 milliarcsec, about the width of the diffraction limited point-spread function (PSF). Sub-resolution-element detection of binaries is possible with HST because of the high signal-to-noise ratio of the observations and the stability of the PSF. Identification and confirmation of binary Trojans is important because a Trojan Tour is one of five possible New Frontiers missions. A binary could constitute a potentially high value target because of the opportunity to study two objects and to test models of the primordial nature of binaries. The potential to derive mass-based physical information from the binary orbit could yield more clues to the origin of Trojans.

  6. Direct, low--frequency scanning capacitance microscopy measurements variations in parasitic capacitance and meniscus formation.

    NASA Astrophysics Data System (ADS)

    Lee, D. T.; Pelz, J. P.; Bhushan, Bharat

    2002-03-01

    We developed a low-noise (<0.4 aF/(Hz)^1/2 at 1 Hz) circuit for direct, calibrated, low-frequency scanning capacitance microscopy (SCM) . We used this circuit to characterize aF-level changes in the parasitic probe-sample capacitance with probe height (2-5 aF/nm) and lateral position (1 ~aF/nm). We also measured the abrupt capacitance change that occurs as the probe tip snaps on/off the surface, which is primarily due to aqueous meniscus formation. For a small meniscus, the capacitance change is a few aF; for a large meniscus, the capacitance change is hundreds of aF. The presence of the meniscus increases the effective area of the capacitance probe, which increases capacitance sensitivity at the expense of spatial resolution. The parasitic capacitance changes and the effect of the meniscus on capacitance must be understood to properly interpret SCM measurements of thin dielectric films, particularly for rough surfaces.

  7. Opening of K+ channels by capacitive stimulation from silicon chip

    NASA Astrophysics Data System (ADS)

    Ulbrich, M. H.; Fromherz, P.

    2005-10-01

    The development of stable neuroelectronic systems requires a stimulation of nerve cells from semiconductor devices without electrochemical effects at the electrolyte/solid interface and without damage of the cell membrane. The interaction must rely on a reversible opening of voltage-gated ion channels by capacitive coupling. In a proof-of-principle experiment, we demonstrate that Kv1.3 potassium channels expressed in HEK293 cells can be opened from an electrolyte/oxide/silicon (EOS) capacitor. A sufficient strength of electrical coupling is achieved by insulating silicon with a thin film of TiO2 to achieve a high capacitance and by removing NaCl from the electrolyte to enhance the resistance of the cell-chip contact. When a decaying voltage ramp is applied to the EOS capacitor, an outward current through the attached cell membrane is observed that is specific for Kv1.3 channels. An open probability up to fifty percent is estimated by comparison with a numerical simulation of the cell-chip contact.

  8. Experimental determination of dielectric barrier discharge capacitance

    NASA Astrophysics Data System (ADS)

    Pipa, A. V.; Hoder, T.; Koskulics, J.; Schmidt, M.; Brandenburg, R.

    2012-07-01

    The determination of electrical parameters (such as instantaneous power, transferred charge, and gas gap voltage) in dielectric barrier discharge (DBD) reactors relies on estimates of key capacitance values. In the classic large-scale sinusoidal-voltage driven DBD, also known as silent or ozonizer discharge, capacitance values can be determined from charge-voltage (Q-V) plot, also called Lissajous figure. For miniature laboratory reactors driven by fast pulsed voltage waveforms with sub-microsecond rise time, the capacitance of the dielectric barriers cannot be evaluated from a single Q-V plot because of the limited applicability of the classical theory. Theoretical determination can be problematic due to electrode edge effects, especially in the case of asymmetrical electrodes. The lack of reliable capacitance estimates leads to a "capacitance bottleneck" that obstructs the determination of other DBD electrical parameters in fast-pulsed reactors. It is suggested to obtain capacitance of dielectric barriers from a plot of the maximal charge versus maximal voltage amplitude (Qmax - Vmax plot) in a manner analogous to the classical approach. The method is examined using measurements of current and voltage waveforms of a coaxial DBD reactor in argon at 100 mbar driven by square voltage pulses with a rise time of 20 ns and with different voltage amplitudes up to 10 kV. Additionally, the applicability of the method has been shown for the data reported in literature measured at 1 bar of nitrogen-oxygen gas mixtures and xenon.

  9. PHOEBE: PHysics Of Eclipsing BinariEs

    NASA Astrophysics Data System (ADS)

    Prsa, Andrej; Matijevic, Gal; Latkovic, Olivera; Vilardell, Francesc; Wils, Patrick

    2011-06-01

    PHOEBE (PHysics Of Eclipsing BinariEs) is a modeling package for eclipsing binary stars, built on top of the widely used WD program (Wilson & Devinney 1971). This introductory paper overviews most important scientific extensions (incorporating observational spectra of eclipsing binaries into the solution-seeking process, extracting individual temperatures from observed color indices, main-sequence constraining and proper treatment of the reddening), numerical innovations (suggested improvements to WD's Differential Corrections method, the new Nelder & Mead's downhill Simplex method) and technical aspects (back-end scripter structure, graphical user interface). While PHOEBE retains 100% WD compatibility, its add-ons are a powerful way to enhance WD by encompassing even more physics and solution reliability.

  10. Capacitively coupled RF diamond-like-carbon reactor

    DOEpatents

    Devlin, David James; Coates, Don Mayo; Archuleta, Thomas Arthur; Barbero, Robert Steven

    2000-01-01

    A process of coating a non-conductive fiber with diamond-like carbon, including passing a non-conductive fiber between a pair of parallel metal grids within a reaction chamber, introducing a hydrocarbon gas into the reaction chamber, forming a plasma within the reaction chamber for a sufficient period of time whereby diamond-like carbon is formed upon the non-conductive fiber, is provided together with a reactor chamber for deposition of diamond-like carbon upon a non-conductive fiber, including a vacuum chamber, a cathode assembly including a pair of electrically isolated opposingly parallel metal grids spaced apart at a distance of less than about 1 centimeter, an anode, a means of introducing a hydrocarbon gas into said vacuum chamber, and a means of generating a plasma within said vacuum chamber.

  11. Narrow gap electronegative capacitive discharges

    NASA Astrophysics Data System (ADS)

    Kawamura, E.; Lieberman, M. A.; Lichtenberg, A. J.

    2013-10-01

    Narrow gap electronegative (EN) capacitive discharges are widely used in industry and have unique features not found in conventional discharges. In this paper, plasma parameters are determined over a range of decreasing gap length L from values for which an electropositive (EP) edge exists (2-region case) to smaller L-values for which the EN region connects directly to the sheath (1-region case). Parametric studies are performed at applied voltage Vrf=500 V for pressures of 10, 25, 50, and 100 mTorr, and additionally at 50 mTorr for 1000 and 2000 V. Numerical results are given for a parallel plate oxygen discharge using a planar 1D3v (1 spatial dimension, 3 velocity components) particle-in-cell (PIC) code. New interesting phenomena are found for the case in which an EP edge does not exist. This 1-region case has not previously been investigated in detail, either numerically or analytically. In particular, attachment in the sheaths is important, and the central electron density ne0 is depressed below the density nesh at the sheath edge. The sheath oscillations also extend into the EN core, creating an edge region lying within the sheath and not characterized by the standard diffusion in an EN plasma. An analytical model is developed using minimal inputs from the PIC results, and compared to the PIC results for a base case at Vrf=500 V and 50 mTorr, showing good agreement. Selected comparisons are made at the other voltages and pressures. A self-consistent model is also developed and compared to the PIC results, giving reasonable agreement.

  12. Narrow gap electronegative capacitive discharges

    SciTech Connect

    Kawamura, E.; Lieberman, M. A.; Lichtenberg, A. J.

    2013-10-15

    Narrow gap electronegative (EN) capacitive discharges are widely used in industry and have unique features not found in conventional discharges. In this paper, plasma parameters are determined over a range of decreasing gap length L from values for which an electropositive (EP) edge exists (2-region case) to smaller L-values for which the EN region connects directly to the sheath (1-region case). Parametric studies are performed at applied voltage V{sub rf}=500 V for pressures of 10, 25, 50, and 100 mTorr, and additionally at 50 mTorr for 1000 and 2000 V. Numerical results are given for a parallel plate oxygen discharge using a planar 1D3v (1 spatial dimension, 3 velocity components) particle-in-cell (PIC) code. New interesting phenomena are found for the case in which an EP edge does not exist. This 1-region case has not previously been investigated in detail, either numerically or analytically. In particular, attachment in the sheaths is important, and the central electron density n{sub e0} is depressed below the density n{sub esh} at the sheath edge. The sheath oscillations also extend into the EN core, creating an edge region lying within the sheath and not characterized by the standard diffusion in an EN plasma. An analytical model is developed using minimal inputs from the PIC results, and compared to the PIC results for a base case at V{sub rf}=500 V and 50 mTorr, showing good agreement. Selected comparisons are made at the other voltages and pressures. A self-consistent model is also developed and compared to the PIC results, giving reasonable agreement.

  13. Capacitive power transfer (CPT) system design using a class E resonant converter circuit

    NASA Astrophysics Data System (ADS)

    Kh., Kamarudin; Saat, Shakir; Yusmarnita, Y.; Ramli. M., S.; Sufiah, A. W. Siti

    2016-02-01

    This paper presents a Capacitive Power Transfer (CPT) system design using a Class E resonant converter circuit. The Class E resonant converter circuit is used to produce a high frequency of alternate current. The purpose of this circuit is to transfer the power via capacitive coupling efficiently. A major advantage of Class E resonant converter circuit is low switching losses. To be specifically, the performance of CPT system at 1MHz of operating frequency and 12V of DC supply voltage is analyzed through experimental works. Finally, a prototype of a CPT system is successfully developed which produced 2mW output power through a capacitive plate size is 12cm × 12cm at 0.1cm of air gap distance.

  14. Amorphous Ni-Co Binary Oxide with Hierarchical Porous Structure for Electrochemical Capacitors.

    PubMed

    Long, Chao; Zheng, Mingtao; Xiao, Yong; Lei, Bingfu; Dong, Hanwu; Zhang, Haoran; Hu, Hang; Liu, Yingliang

    2015-11-11

    A simple and outstanding approach is provided to fabricate amorphous structure Ni-Co binary oxide as supercapacitors electrode materials. We can easily obtain porous Ni-Co oxides composite materials via chemical bath deposition and subsequent calcination without any template or complicate operation procedures. The amorphous porous Ni-Co binary oxide exhibits brilliant electrochemical performance: first, the peculiar porous structure can effectively transport electrolytes and shorten the ion diffusion path; second, binary composition and amorphous character introduce more surface defects for redox reactions. It shows a high specific capacitance up to 1607 F g(-1) and can be cycled for 2000 cycles with 91% capacitance retention. In addition, the asymmetric supercapacitor delivers superior energy density of 28 W h kg(-1), and the maximum power density of 3064 W kg(-1) with a high energy density of 10 W h kg(-1).

  15. Electrical Capacitance Volume Tomography with High-Contrast Dielectrics

    NASA Technical Reports Server (NTRS)

    Nurge, Mark

    2010-01-01

    The Electrical Capacitance Volume Tomography (ECVT) system has been designed to complement the tools created to sense the presence of water in nonconductive spacecraft materials, by helping to not only find the approximate location of moisture but also its quantity and depth. The ECVT system has been created for use with a new image reconstruction algorithm capable of imaging high-contrast dielectric distributions. Rather than relying solely on mutual capacitance readings as is done in traditional electrical capacitance tomography applications, this method reconstructs high-resolution images using only the self-capacitance measurements. The image reconstruction method assumes that the material under inspection consists of a binary dielectric distribution, with either a high relative dielectric value representing the water or a low dielectric value for the background material. By constraining the unknown dielectric material to one of two values, the inverse math problem that must be solved to generate the image is no longer ill-determined. The image resolution becomes limited only by the accuracy and resolution of the measurement circuitry. Images were reconstructed using this method with both synthetic and real data acquired using an aluminum structure inserted at different positions within the sensing region. The cuboid geometry of the system has two parallel planes of 16 conductors arranged in a 4 4 pattern. The electrode geometry consists of parallel planes of copper conductors, connected through custom-built switch electronics, to a commercially available capacitance to digital converter. The figure shows two 4 4 arrays of electrodes milled from square sections of copper-clad circuit-board material and mounted on two pieces of glass-filled plastic backing, which were cut to approximately square shapes, 10 cm on a side. Each electrode is placed on 2.0-cm centers. The parallel arrays were mounted with the electrode arrays approximately 3 cm apart. The open ends

  16. Electrical Capacitance Volume Tomography: Design and Applications

    PubMed Central

    Wang, Fei; Marashdeh, Qussai; Fan, Liang-Shih; Warsito, Warsito

    2010-01-01

    This article reports recent advances and progress in the field of electrical capacitance volume tomography (ECVT). ECVT, developed from the two-dimensional electrical capacitance tomography (ECT), is a promising non-intrusive imaging technology that can provide real-time three-dimensional images of the sensing domain. Images are reconstructed from capacitance measurements acquired by electrodes placed on the outside boundary of the testing vessel. In this article, a review of progress on capacitance sensor design and applications to multi-phase flows is presented. The sensor shape, electrode configuration, and the number of electrodes that comprise three key elements of three-dimensional capacitance sensors are illustrated. The article also highlights applications of ECVT sensors on vessels of various sizes from 1 to 60 inches with complex geometries. Case studies are used to show the capability and validity of ECVT. The studies provide qualitative and quantitative real-time three-dimensional information of the measuring domain under study. Advantages of ECVT render it a favorable tool to be utilized for industrial applications and fundamental multi-phase flow research. PMID:22294905

  17. Ion channels, phosphorylation and mammalian sperm capacitation.

    PubMed

    Visconti, Pablo E; Krapf, Dario; de la Vega-Beltrán, José Luis; Acevedo, Juan José; Darszon, Alberto

    2011-05-01

    Sexually reproducing animals require an orchestrated communication between spermatozoa and the egg to generate a new individual. Capacitation, a maturational complex phenomenon that occurs in the female reproductive tract, renders spermatozoa capable of binding and fusing with the oocyte, and it is a requirement for mammalian fertilization. Capacitation encompasses plasma membrane reorganization, ion permeability regulation, cholesterol loss and changes in the phosphorylation state of many proteins. Novel tools to study sperm ion channels, image intracellular ionic changes and proteins with better spatial and temporal resolution, are unraveling how modifications in sperm ion transport and phosphorylation states lead to capacitation. Recent evidence indicates that two parallel pathways regulate phosphorylation events leading to capacitation, one of them requiring activation of protein kinase A and the second one involving inactivation of ser/thr phosphatases. This review examines the involvement of ion transporters and phosphorylation signaling processes needed for spermatozoa to achieve capacitation. Understanding the molecular mechanisms leading to fertilization is central for societies to deal with rising male infertility rates, to develop safe male gamete-based contraceptives and to preserve biodiversity through better assisted fertilization strategies.

  18. Capacitive Deionization of High-Salinity Solutions

    SciTech Connect

    Sharma, Ketki; Gabitto, Jorge; Mayes, Richard T.; Yiacoumi, Sotira; Bilheux, Hassina Z.; Walker, Lakeisha M.H.; Dai, Sheng; Tsouris, Costas

    2014-12-22

    Desalination of high salinity solutions has been studied using a novel experimental technique and a theoretical model. Neutron imaging has been employed to visualize lithium ions in mesoporous carbon materials, which are used as electrodes in capacitive deionization for water desalination. Experiments were conducted with a flow-through capacitive deionization cell designed for neutron imaging and with lithium chloride (6LiCl) as the electrolyte. Sequences of neutron images have been obtained at a relatively high concentration of lithium chloride (6LiCl) solution to provide information on the transport of ions within the electrodes. A new model that computes the individual ionic concentration profiles inside mesoporous carbon electrodes has been used to simulate the capacitive deionization process. Modifications have also been introduced into the simulation model to calculate results at high electrolyte concentrations. Experimental data and simulation results provide insight into why capacitive deionization is not effective for desalination of high ionic-strength solutions. The combination of experimental information, obtained through neutron imaging, with the theoretical model will help in the design of capacitive deionization devices, which can improve the process for high ionic-strength solutions.

  19. Capacitive Deionization of High-Salinity Solutions

    DOE PAGESBeta

    Sharma, Ketki; Gabitto, Jorge; Mayes, Richard T.; Yiacoumi, Sotira; Bilheux, Hassina Z.; Walker, Lakeisha M.H.; Dai, Sheng; Tsouris, Costas

    2014-12-22

    Desalination of high salinity solutions has been studied using a novel experimental technique and a theoretical model. Neutron imaging has been employed to visualize lithium ions in mesoporous carbon materials, which are used as electrodes in capacitive deionization for water desalination. Experiments were conducted with a flow-through capacitive deionization cell designed for neutron imaging and with lithium chloride (6LiCl) as the electrolyte. Sequences of neutron images have been obtained at a relatively high concentration of lithium chloride (6LiCl) solution to provide information on the transport of ions within the electrodes. A new model that computes the individual ionic concentration profilesmore » inside mesoporous carbon electrodes has been used to simulate the capacitive deionization process. Modifications have also been introduced into the simulation model to calculate results at high electrolyte concentrations. Experimental data and simulation results provide insight into why capacitive deionization is not effective for desalination of high ionic-strength solutions. The combination of experimental information, obtained through neutron imaging, with the theoretical model will help in the design of capacitive deionization devices, which can improve the process for high ionic-strength solutions.« less

  20. Ion channels, phosphorylation and mammalian sperm capacitation

    PubMed Central

    Visconti, Pablo E; Krapf, Dario; de la Vega-Beltrán, José Luis; Acevedo, Juan José; Darszon, Alberto

    2011-01-01

    Sexually reproducing animals require an orchestrated communication between spermatozoa and the egg to generate a new individual. Capacitation, a maturational complex phenomenon that occurs in the female reproductive tract, renders spermatozoa capable of binding and fusing with the oocyte, and it is a requirement for mammalian fertilization. Capacitation encompasses plasma membrane reorganization, ion permeability regulation, cholesterol loss and changes in the phosphorylation state of many proteins. Novel tools to study sperm ion channels, image intracellular ionic changes and proteins with better spatial and temporal resolution, are unraveling how modifications in sperm ion transport and phosphorylation states lead to capacitation. Recent evidence indicates that two parallel pathways regulate phosphorylation events leading to capacitation, one of them requiring activation of protein kinase A and the second one involving inactivation of ser/thr phosphatases. This review examines the involvement of ion transporters and phosphorylation signaling processes needed for spermatozoa to achieve capacitation. Understanding the molecular mechanisms leading to fertilization is central for societies to deal with rising male infertility rates, to develop safe male gamete-based contraceptives and to preserve biodiversity through better assisted fertilization strategies. PMID:21540868

  1. Microphonics in biopotential measurements with capacitive electrodes.

    PubMed

    Luna-Lozano, Pablo S; Pallas-Areny, Ramon

    2010-01-01

    Biopotential measurements with capacitive electrodes do not need any direct contact between electrode and skin, which saves the time devoted to expose and prepare the contact area when measuring with conductive electrodes. However, mechanical vibrations resulting from physiological functions such as respiration and cardiac contraction can change the capacitance of the electrode and affect the recordings. This transformation of mechanical vibrations into undesired electric signals is termed microphonics. We have evaluated microphonics in capacitive ECG recordings obtained from a dressed subject seated on a common chair with electrodes placed on the front side of the backrest of the chair. Depending on the softness of the backrest, the recordings may be clearly affected by the displacement of the thorax back wall due to the respiration and to the heart's mechanical activity.

  2. A high performance, variable capacitance accelerometer

    NASA Astrophysics Data System (ADS)

    Wilner, L. Bruce

    1988-12-01

    A variable capacitance acceleration sensor is described. Manufactured using silicon microfabrication techniques, the sensor uses a midplane, flat plate suspension, gas damping, and overrange stops. The sensor is assembled from three silicon wafers, using anodic bonds to inlays of borosilicate glass. Typical sensor properties are 7-pF active capacitance, 3-pF tare capacitance, a response of 0.05 pF/G, a resonance frequency of 3.4 kHz, and damping 0.7 critical. It is concluded that this sensor, with appropriate electronics, forms an accelerometer with an order-of-magnitude greater sensitivity-bandwidth product than a comparable piezoresistive acclerometer, and with extraordinary shock resistance.

  3. Design and simulation of MEMS capacitive magnetometer

    NASA Astrophysics Data System (ADS)

    Jyoti, Aditi, Tripathi, C. C.; Gopal, Ram

    2016-04-01

    This paper presents the design and simulation of a MEMS Capacitive Magnetometer using FEM (Finite Element Method) tool COMSOL Multiphysics 4.3b and results from this simulation are closely matched with analytically calculated results. A comb drive structure is used for actuation purpose which operates at resonant frequency of device is 11.791 kHz to achieve maximum displacement. A magnetic field in z-axis can be detected by this comb drive structure. Quality factor of MEMS capacitive magnetometer obtained is 18 and it has good linear response in the magnetic field range of 100 µT.

  4. Capacitive sensor for high resolution weld seam tracking

    SciTech Connect

    Schmitt, D.J.; Novak, J.L.; Akins, J.L.

    1995-05-01

    A non-contact capacitive sensing system has been developed for guiding automated welding equipment along typical v-groove geometries. The Multi-Axis Seam Tracking (MAST) sensor has been designed to produce four electric fields for locating and measuring the v-groove geometry. In this system, the MAST sensor is coupled with a set of signal conditioning electronics making it possible to output four varying voltages proportional to the electric field perturbations. This output is used for motion control purposes by the automated welding platform to guide the weld torch directly over the center of the v-groove. This report discusses the development of this capacitive sensing system. A functional description of the system and MAST sensor response characteristics for typical weld v-groove geometries are provided. The effects of the harsh thermal and electrical noise environments of plasma arc welding on sensor performance are discussed. A comparison of MAST sensor fabrication from glass-epoxy and thick-film ceramic substrates is provided. Finally, results of v-groove tracking experiments on a robotic welding platform are described.

  5. Hybrid black-hole binary initial data

    NASA Astrophysics Data System (ADS)

    Mundim, Bruno; Kelly, Bernard; Zlochower, Yosef; Nakano, Hiroyuki; Campanelli, Manuela

    2011-04-01

    Traditional black-hole binary puncture initial data is conformally flat. This unphysical assumption is coupled with a lack of radiation signature from the binary's past life. As a result, waveforms extracted from evolutions of this data display an abrupt jump. In Kelly et al. [Class.Quant.Grav.27:114005,2010], a new binary black-hole initial data with radiation contents derived in the post-Newtonian (PN) calculation was adapted to puncture evolutions in numerical relativity. This data satisfies the constraint equations to the 2.5PN order, and contains a transverse-traceless ``wavy'' metric contribution, violating the standard assumption of conformal flatness. Although the evolution contained less spurious radiation, there were undesired features; the unphysical horizon mass loss and the large initial orbital eccentricity. Introducing a hybrid approach to the initial data evaluation, we significantly reduce these undesired features. Thanks NSF and NASA for support.

  6. Hybrid Black-Hole Binary Initial Data

    NASA Technical Reports Server (NTRS)

    Mundim, Bruno C.; Kelly, Bernard J.; Nakano, Hiroyuki; Zlochower, Yosef; Campanelli, Manuela

    2010-01-01

    "Traditional black-hole binary puncture initial data is conformally flat. This unphysical assumption is coupled with a lack of radiation signature from the binary's past life. As a result, waveforms extracted from evolutions of this data display an abrupt jump. In Kelly et al. [Class. Quantum Grav. 27:114005 (2010)], a new binary black-hole initial data with radiation contents derived in the post-Newtonian (PN) calculations was adapted to puncture evolutions in numerical relativity. This data satisfies the constraint equations to the 2.5PN order, and contains a transverse-traceless "wavy" metric contribution, violating the standard assumption of conformal flatness. Although the evolution contained less spurious radiation, there were undesired features; the unphysical horizon mass loss and the large initial orbital eccentricity. Introducing a hybrid approach to the initial data evaluation, we significantly reduce these undesired features."

  7. Rapid Compact Binary Coalescence Parameter Estimation

    NASA Astrophysics Data System (ADS)

    Pankow, Chris; Brady, Patrick; O'Shaughnessy, Richard; Ochsner, Evan; Qi, Hong

    2016-03-01

    The first observation run with second generation gravitational-wave observatories will conclude at the beginning of 2016. Given their unprecedented and growing sensitivity, the benefit of prompt and accurate estimation of the orientation and physical parameters of binary coalescences is obvious in its coupling to electromagnetic astrophysics and observations. Popular Bayesian schemes to measure properties of compact object binaries use Markovian sampling to compute the posterior. While very successful, in some cases, convergence is delayed until well after the electromagnetic fluence has subsided thus diminishing the potential science return. With this in mind, we have developed a scheme which is also Bayesian and simply parallelizable across all available computing resources, drastically decreasing convergence time to a few tens of minutes. In this talk, I will emphasize the complementary use of results from low latency gravitational-wave searches to improve computational efficiency and demonstrate the capabilities of our parameter estimation framework with a simulated set of binary compact object coalescences.

  8. Negative capacitance in multidomain ferroelectric superlattices.

    PubMed

    Zubko, Pavlo; Wojdeł, Jacek C; Hadjimichael, Marios; Fernandez-Pena, Stéphanie; Sené, Anaïs; Luk'yanchuk, Igor; Triscone, Jean-Marc; Íñiguez, Jorge

    2016-06-23

    The stability of spontaneous electrical polarization in ferroelectrics is fundamental to many of their current applications, which range from the simple electric cigarette lighter to non-volatile random access memories. Research on nanoscale ferroelectrics reveals that their behaviour is profoundly different from that in bulk ferroelectrics, which could lead to new phenomena with potential for future devices. As ferroelectrics become thinner, maintaining a stable polarization becomes increasingly challenging. On the other hand, intentionally destabilizing this polarization can cause the effective electric permittivity of a ferroelectric to become negative, enabling it to behave as a negative capacitance when integrated in a heterostructure. Negative capacitance has been proposed as a way of overcoming fundamental limitations on the power consumption of field-effect transistors. However, experimental demonstrations of this phenomenon remain contentious. The prevalent interpretations based on homogeneous polarization models are difficult to reconcile with the expected strong tendency for domain formation, but the effect of domains on negative capacitance has received little attention. Here we report negative capacitance in a model system of multidomain ferroelectric-dielectric superlattices across a wide range of temperatures, in both the ferroelectric and paraelectric phases. Using a phenomenological model, we show that domain-wall motion not only gives rise to negative permittivity, but can also enhance, rather than limit, its temperature range. Our first-principles-based atomistic simulations provide detailed microscopic insight into the origin of this phenomenon, identifying the dominant contribution of near-interface layers and paving the way for its future exploitation. PMID:27296225

  9. Negative capacitance in multidomain ferroelectric superlattices

    NASA Astrophysics Data System (ADS)

    Zubko, Pavlo; Wojdeł, Jacek C.; Hadjimichael, Marios; Fernandez-Pena, Stéphanie; Sené, Anaïs; Luk'Yanchuk, Igor; Triscone, Jean-Marc; Íñiguez, Jorge

    2016-06-01

    The stability of spontaneous electrical polarization in ferroelectrics is fundamental to many of their current applications, which range from the simple electric cigarette lighter to non-volatile random access memories. Research on nanoscale ferroelectrics reveals that their behaviour is profoundly different from that in bulk ferroelectrics, which could lead to new phenomena with potential for future devices. As ferroelectrics become thinner, maintaining a stable polarization becomes increasingly challenging. On the other hand, intentionally destabilizing this polarization can cause the effective electric permittivity of a ferroelectric to become negative, enabling it to behave as a negative capacitance when integrated in a heterostructure. Negative capacitance has been proposed as a way of overcoming fundamental limitations on the power consumption of field-effect transistors. However, experimental demonstrations of this phenomenon remain contentious. The prevalent interpretations based on homogeneous polarization models are difficult to reconcile with the expected strong tendency for domain formation, but the effect of domains on negative capacitance has received little attention. Here we report negative capacitance in a model system of multidomain ferroelectric-dielectric superlattices across a wide range of temperatures, in both the ferroelectric and paraelectric phases. Using a phenomenological model, we show that domain-wall motion not only gives rise to negative permittivity, but can also enhance, rather than limit, its temperature range. Our first-principles-based atomistic simulations provide detailed microscopic insight into the origin of this phenomenon, identifying the dominant contribution of near-interface layers and paving the way for its future exploitation.

  10. Constant capacitance in nanopores of carbon monoliths.

    PubMed

    García-Gómez, Alejandra; Moreno-Fernández, Gelines; Lobato, Belén; Centeno, Teresa A

    2015-06-28

    The results obtained for binder-free electrodes made of carbon monoliths with narrow micropore size distributions confirm that the specific capacitance in the electrolyte (C2H5)4NBF4/acetonitrile does not depend significantly on the micropore size and support the foregoing constant result of 0.094 ± 0.011 F m(-2).

  11. Teaching of Inductive and Capacitive Reactance.

    ERIC Educational Resources Information Center

    MacInnes, I.; Jeffrey, W. S.

    1983-01-01

    Discusses how understanding mechanical systems and their graphic representation can be of value when teaching inductive and capacitive reactance, in particular, the response of inductors and capacitors to an alternating potential difference. Suggests that mechanical systems be taught, not just before introducing reactance but earlier in the…

  12. Capacitors and Resistance-Capacitance Networks.

    ERIC Educational Resources Information Center

    Balabanian, Norman; Root, Augustin A.

    This programed textbook was developed under a contract with the United States Office of Education as Number 5 in a series of materials for use in an electrical engineering sequence. It is divided into three parts--(1) capacitors, (2) voltage-current relationships, and (3) simple resistance-capacitance networks. (DH)

  13. Negative capacitance in multidomain ferroelectric superlattices

    NASA Astrophysics Data System (ADS)

    Zubko, Pavlo; Wojdeł, Jacek C.; Hadjimichael, Marios; Fernandez-Pena, Stéphanie; Sené, Anaïs; Luk’Yanchuk, Igor; Triscone, Jean-Marc; Íñiguez, Jorge

    2016-06-01

    The stability of spontaneous electrical polarization in ferroelectrics is fundamental to many of their current applications, which range from the simple electric cigarette lighter to non-volatile random access memories. Research on nanoscale ferroelectrics reveals that their behaviour is profoundly different from that in bulk ferroelectrics, which could lead to new phenomena with potential for future devices. As ferroelectrics become thinner, maintaining a stable polarization becomes increasingly challenging. On the other hand, intentionally destabilizing this polarization can cause the effective electric permittivity of a ferroelectric to become negative, enabling it to behave as a negative capacitance when integrated in a heterostructure. Negative capacitance has been proposed as a way of overcoming fundamental limitations on the power consumption of field-effect transistors. However, experimental demonstrations of this phenomenon remain contentious. The prevalent interpretations based on homogeneous polarization models are difficult to reconcile with the expected strong tendency for domain formation, but the effect of domains on negative capacitance has received little attention. Here we report negative capacitance in a model system of multidomain ferroelectric–dielectric superlattices across a wide range of temperatures, in both the ferroelectric and paraelectric phases. Using a phenomenological model, we show that domain-wall motion not only gives rise to negative permittivity, but can also enhance, rather than limit, its temperature range. Our first-principles-based atomistic simulations provide detailed microscopic insight into the origin of this phenomenon, identifying the dominant contribution of near-interface layers and paving the way for its future exploitation.

  14. Negative capacitance in multidomain ferroelectric superlattices.

    PubMed

    Zubko, Pavlo; Wojdeł, Jacek C; Hadjimichael, Marios; Fernandez-Pena, Stéphanie; Sené, Anaïs; Luk'yanchuk, Igor; Triscone, Jean-Marc; Íñiguez, Jorge

    2016-06-23

    The stability of spontaneous electrical polarization in ferroelectrics is fundamental to many of their current applications, which range from the simple electric cigarette lighter to non-volatile random access memories. Research on nanoscale ferroelectrics reveals that their behaviour is profoundly different from that in bulk ferroelectrics, which could lead to new phenomena with potential for future devices. As ferroelectrics become thinner, maintaining a stable polarization becomes increasingly challenging. On the other hand, intentionally destabilizing this polarization can cause the effective electric permittivity of a ferroelectric to become negative, enabling it to behave as a negative capacitance when integrated in a heterostructure. Negative capacitance has been proposed as a way of overcoming fundamental limitations on the power consumption of field-effect transistors. However, experimental demonstrations of this phenomenon remain contentious. The prevalent interpretations based on homogeneous polarization models are difficult to reconcile with the expected strong tendency for domain formation, but the effect of domains on negative capacitance has received little attention. Here we report negative capacitance in a model system of multidomain ferroelectric-dielectric superlattices across a wide range of temperatures, in both the ferroelectric and paraelectric phases. Using a phenomenological model, we show that domain-wall motion not only gives rise to negative permittivity, but can also enhance, rather than limit, its temperature range. Our first-principles-based atomistic simulations provide detailed microscopic insight into the origin of this phenomenon, identifying the dominant contribution of near-interface layers and paving the way for its future exploitation.

  15. Electron heating in low pressure capacitive discharges revisited

    SciTech Connect

    Kawamura, E.; Lieberman, M. A.; Lichtenberg, A. J.

    2014-12-15

    The electrons in capacitively coupled plasmas (CCPs) absorb energy via ohmic heating due to electron-neutral collisions and stochastic heating due to momentum transfer from high voltage moving sheaths. We use Particle-in-Cell (PIC) simulations to explore these heating mechanisms and to compare the PIC results with available theories on ohmic and stochastic heating. The PIC results for ohmic heating show good agreement with the ohmic heating calculation of Lafleur et al. [Phys. Plasmas 20, 124503 (2013)]. The PIC results for stochastic heating in low pressure CCPs with collisionless sheaths show good agreement with the stochastic heating model of Kaganovich et al. [IEEE Trans. Plasma Sci. 34, 696 (2006)], which revises the hard wall asymptotic model of Lieberman [IEEE Trans. Plasma Sci. 16, 638 (1988)] by taking current continuity and bulk oscillation into account.

  16. Frequency scanning capaciflector for capacitively determining the material properties

    NASA Technical Reports Server (NTRS)

    Campbell, Charles E. (Inventor)

    1996-01-01

    A capaciflector sensor system scanned in frequency is used to detect the permittivity of the material of an object being sensed. A capaciflector sensor element, coupled to current-measuring voltage follower circuitry, is driven by a frequency swept oscillator and generates an output which corresponds to capacity as a function of the input frequency. This swept frequency information is fed into apparatus e.g. a digital computer for comparing the shape of the capacitance vs. frequency curve against characteristic capacitor vs. frequency curves for a variety of different materials which are stored, for example, in a digital memory of the computer or a database. Using a technique of pattern matching, a determination is made as to the identification of the material. Also, when desirable, the distance between the sensor and the object can be determined.

  17. Capacitive micromachined ultrasonic transducers for medical imaging and therapy

    PubMed Central

    Khuri-Yakub, Butrus T.; Oralkan, Ömer

    2011-01-01

    Capacitive micromachined ultrasonic transducers (CMUTs) have been subject to extensive research for the last two decades. Although they were initially developed for air-coupled applications, today their main application space is medical imaging and therapy. This paper first presents a brief description of CMUTs, their basic structure, and operating principles. Our progression of developing several generations of fabrication processes is discussed with an emphasis on the advantages and disadvantages of each process. Monolithic and hybrid approaches for integrating CMUTs with supporting integrated circuits are surveyed. Several prototype transducer arrays with integrated frontend electronic circuits we developed and their use for 2-D and 3-D, anatomical and functional imaging, and ablative therapies are described. The presented results prove the CMUT as a MEMS technology for many medical diagnostic and therapeutic applications. PMID:21860542

  18. Characterization and modeling of capacitances in FD-SOI devices

    NASA Astrophysics Data System (ADS)

    Ben Akkez, Imed; Cros, Antoine; Fenouillet-Beranger, Claire; Perreau, P.; Margain, A.; Boeuf, Frederic; Balestra, Francis; Ghibaudo, Gérard

    2012-05-01

    Gate-to-channel capacitance Cgc(Vg) data obtained on FD-SOI MOS devices with gate lengths down to 35 nm are first reported. Thus, a 2D numerical simulation procedure allowing to calculate the total device capacitance and parasitic capacitances is developed. This enabled us to discriminate the respective contributions of all parasitic components such as spacer, overlap, inner fringe and buried oxide capacitances in the structure.

  19. Membrane hyperpolarization during human sperm capacitation

    PubMed Central

    López-González, I.; Torres-Rodríguez, P.; Sánchez-Carranza, O.; Solís-López, A.; Santi, C.M.; Darszon, A.; Treviño, C.L.

    2014-01-01

    Sperm capacitation is a complex and indispensable physiological process that spermatozoa must undergo in order to acquire fertilization capability. Spermatozoa from several mammalian species, including mice, exhibit a capacitation-associated plasma membrane hyperpolarization, which is necessary for the acrosome reaction to occur. Despite its importance, this hyperpolarization event has not been adequately examined in human sperm. In this report we used flow cytometry to show that a subpopulation of human sperm indeed undergo a plasma membrane hyperpolarization upon in vitro capacitation. This hyperpolarization correlated with two other well-characterized capacitation parameters, namely an increase in intracellular pH and Ca2+ concentration, measured also by flow cytometry. We found that sperm membrane hyperpolarization was completely abolished in the presence of a high external K+ concentration (60 mM), indicating the participation of K+ channels. In order to identify, which of the potential K+ channels were involved in this hyperpolarization, we used different K+ channel inhibitors including charybdotoxin, slotoxin and iberiotoxin (which target Slo1) and clofilium (a more specific blocker for Slo3). All these K+ channel antagonists inhibited membrane hyperpolarization to a similar extent, suggesting that both members of the Slo family may potentially participate. Two very recent papers recorded K+ currents in human sperm electrophysiologically, with some contradictory results. In the present work, we show through immunoblotting that Slo3 channels are present in the human sperm membrane. In addition, we found that human Slo3 channels expressed in CHO cells were sensitive to clofilium (50 μM). Considered altogether, our data indicate that Slo1 and Slo3 could share the preponderant role in the capacitation-associated hyperpolarization of human sperm in contrast to what has been previously reported for mouse sperm, where Slo3 channels are the main contributors to the

  20. Membrane hyperpolarization during human sperm capacitation.

    PubMed

    López-González, I; Torres-Rodríguez, P; Sánchez-Carranza, O; Solís-López, A; Santi, C M; Darszon, A; Treviño, C L

    2014-07-01

    Sperm capacitation is a complex and indispensable physiological process that spermatozoa must undergo in order to acquire fertilization capability. Spermatozoa from several mammalian species, including mice, exhibit a capacitation-associated plasma membrane hyperpolarization, which is necessary for the acrosome reaction to occur. Despite its importance, this hyperpolarization event has not been adequately examined in human sperm. In this report we used flow cytometry to show that a subpopulation of human sperm indeed undergo a plasma membrane hyperpolarization upon in vitro capacitation. This hyperpolarization correlated with two other well-characterized capacitation parameters, namely an increase in intracellular pH and Ca(2+) concentration, measured also by flow cytometry. We found that sperm membrane hyperpolarization was completely abolished in the presence of a high external K(+) concentration (60 mM), indicating the participation of K(+) channels. In order to identify, which of the potential K(+) channels were involved in this hyperpolarization, we used different K(+) channel inhibitors including charybdotoxin, slotoxin and iberiotoxin (which target Slo1) and clofilium (a more specific blocker for Slo3). All these K(+) channel antagonists inhibited membrane hyperpolarization to a similar extent, suggesting that both members of the Slo family may potentially participate. Two very recent papers recorded K(+) currents in human sperm electrophysiologically, with some contradictory results. In the present work, we show through immunoblotting that Slo3 channels are present in the human sperm membrane. In addition, we found that human Slo3 channels expressed in CHO cells were sensitive to clofilium (50 μM). Considered altogether, our data indicate that Slo1 and Slo3 could share the preponderant role in the capacitation-associated hyperpolarization of human sperm in contrast to what has been previously reported for mouse sperm, where Slo3 channels are the main

  1. Capacitance, entanglement energetics and persistent currents of mesoscopic rings

    NASA Astrophysics Data System (ADS)

    Buttiker, Markus

    2009-03-01

    Small rings are a quintessential mesoscopic system. As a consequence of quantum coherence small normal metal rings support a persistent current. Novel experimental techniques will permit to investigate rings with geometries which highlight the effects of interactions. We discuss rings with in-line and side quantum dots. In the Coulomb blockade regime we derive an effective two-state Hamiltonian and discuss the flux dependence of the Coulomb blockade peaks in the capacitance and the persistent current [1]. Different nearly degenerate charge configurations of the ring-dot system become entangled with an electrical environment. With an environment consisting of an external resistor capacitively coupled to the ring and dot the entire system maps on a spin boson problem. Analysis shows that the visibility of the persistent current decreases with increasing coupling to the environment [2]. The system-bath entanglement which is at the origin of this phenomenon can be detected by projective measurements of the energy of the ring-dot subsystem or the persistent current: even in the ground state of the total system the ring can be found with some probability in the energetically higher lying state [3]. The distribution of energy or of the persistent currents is a direct measure of the system bath entanglement. [4pt] [1] M. Buttiker and C. A. Stafford, Phys. Rev. Lett. 76, 495 (1996); [0pt] [2] P. Cedraschi, V. V. Ponomarenko, and M. Buttiker, Phys. Rev. Lett. 84, 346 (2000); P. Cedraschi and M. Buttiker, Annals of Physics, 289, 1 (2001). [0pt] [3] A. N. Jordan and M. Buttiker, Phys. Rev. Lett. 92, 247901 (2004); M. Buttiker and A. N. Jordan, Physica E 29, 272 (2005); K. Le Hur, Annals of Physics, 323, 2208 (2008).

  2. A Novel Single-Excitation Capacitive Angular Position Sensor Design

    PubMed Central

    Hou, Bo; Zhou, Bin; Song, Mingliang; Lin, Zhihui; Zhang, Rong

    2016-01-01

    This paper presents a high-precision capacitive angular position sensor (CAPS). The CAPS is designed to be excited by a single voltage to eliminate the matching errors of multi-excitations, and it is mainly composed of excitation electrodes, coupling electrodes, petal-form sensitive electrodes and a set of collection electrodes. A sinusoidal voltage is applied on the excitation electrodes, then the voltage couples to the coupling electrodes and sensitive electrodes without contact. The sensitive electrodes together with the set of collection electrodes encode the angular position to amplitude-modulated signals, and in order to increase the scale factor, the sensitive electrodes are patterned in the shape of petal-form sinusoidal circles. By utilizing a resolver demodulation method, the amplitude-modulated signals are digitally decoded to get the angular position. A prototype of the CAPS is fabricated and tested. The measurement results show that the accuracy of the sensor is 0.0036°, the resolution is 0.0009° and the nonlinearity over the full range is 0.008° (after compensation), indicating that the CAPS has great potential to be applied in high-precision applications with a low cost. PMID:27483278

  3. A Novel Single-Excitation Capacitive Angular Position Sensor Design.

    PubMed

    Hou, Bo; Zhou, Bin; Song, Mingliang; Lin, Zhihui; Zhang, Rong

    2016-01-01

    This paper presents a high-precision capacitive angular position sensor (CAPS). The CAPS is designed to be excited by a single voltage to eliminate the matching errors of multi-excitations, and it is mainly composed of excitation electrodes, coupling electrodes, petal-form sensitive electrodes and a set of collection electrodes. A sinusoidal voltage is applied on the excitation electrodes, then the voltage couples to the coupling electrodes and sensitive electrodes without contact. The sensitive electrodes together with the set of collection electrodes encode the angular position to amplitude-modulated signals, and in order to increase the scale factor, the sensitive electrodes are patterned in the shape of petal-form sinusoidal circles. By utilizing a resolver demodulation method, the amplitude-modulated signals are digitally decoded to get the angular position. A prototype of the CAPS is fabricated and tested. The measurement results show that the accuracy of the sensor is 0.0036°, the resolution is 0.0009° and the nonlinearity over the full range is 0.008° (after compensation), indicating that the CAPS has great potential to be applied in high-precision applications with a low cost.

  4. Binaries in globular clusters

    NASA Technical Reports Server (NTRS)

    Hut, Piet; Mcmillan, Steve; Goodman, Jeremy; Mateo, Mario; Phinney, E. S.; Pryor, Carlton; Richer, Harvey B.; Verbunt, Frank; Weinberg, Martin

    1992-01-01

    Recent observations have shown that globular clusters contain a substantial number of binaries most of which are believed to be primordial. We discuss different successful optical search techniques, based on radial-velocity variables, photometric variables, and the positions of stars in the color-magnitude diagram. In addition, we review searches in other wavelengths, which have turned up low-mass X-ray binaries and more recently a variety of radio pulsars. On the theoretical side, we give an overview of the different physical mechanisms through which individual binaries evolve. We discuss the various simulation techniques which recently have been employed to study the effects of a primordial binary population, and the fascinating interplay between stellar evolution and stellar dynamics which drives globular-cluster evolution.

  5. Sometimes binary is better

    NASA Astrophysics Data System (ADS)

    Sprows, David

    2015-04-01

    This note uses material involving perfect numbers and Zeno's paradoxes to show that although most students prefer to use base 10 when working with mathematical concepts there are times when the binary system is best.

  6. Double Degenerate Binary Systems

    SciTech Connect

    Yakut, K.

    2011-09-21

    In this study, angular momentum loss via gravitational radiation in double degenerate binary (DDB)systems (NS + NS, NS + WD, WD + WD, and AM CVn) is studied. Energy loss by gravitational waves has been estimated for each type of systems.

  7. X-ray binaries

    NASA Technical Reports Server (NTRS)

    1976-01-01

    Satellite X-ray experiments and ground-based programs aimed at observation of X-ray binaries are discussed. Experiments aboard OAO-3, OSO-8, Ariel 5, Uhuru, and Skylab are included along with rocket and ground-based observations. Major topics covered are: Her X-1, Cyg X-3, Cen X-3, Cyg X-1, the transient source A0620-00, other possible X-ray binaries, and plans and prospects for future observational programs.

  8. Binary-Symmetry Detection

    NASA Technical Reports Server (NTRS)

    Lopez, Hiram

    1987-01-01

    Transmission errors for zeros and ones tabulated separately. Binary-symmetry detector employs psuedo-random data pattern used as test message coming through channel. Message then modulo-2 added to locally generated and synchronized version of test data pattern in same manner found in manufactured test sets of today. Binary symmetrical channel shows nearly 50-percent ones to 50-percent zeroes correspondence. Degree of asymmetry represents imbalances due to either modulation, transmission, or demodulation processes of system when perturbed by noise.

  9. Scattering from binary optics

    NASA Technical Reports Server (NTRS)

    Ricks, Douglas W.

    1993-01-01

    There are a number of sources of scattering in binary optics: etch depth errors, line edge errors, quantization errors, roughness, and the binary approximation to the ideal surface. These sources of scattering can be systematic (deterministic) or random. In this paper, scattering formulas for both systematic and random errors are derived using Fourier optics. These formulas can be used to explain the results of scattering measurements and computer simulations.

  10. Spectroscopic Binary Stars

    NASA Astrophysics Data System (ADS)

    Batten, A.; Murdin, P.

    2000-11-01

    Historically, spectroscopic binary stars were binary systems whose nature was discovered by the changing DOPPLER EFFECT or shift of the spectral lines of one or both of the component stars. The observed Doppler shift is a combination of that produced by the constant RADIAL VELOCITY (i.e. line-of-sight velocity) of the center of mass of the whole system, and the variable shift resulting from the o...

  11. Orbits of 6 Binaries

    NASA Astrophysics Data System (ADS)

    Olevic, D.; Cvetkovic, Z.

    In this paper the orbits of binaries WDS 10093+2020 = A 2145, WDS 21074-0814 = BU 368 AB and WDS 22288-0001 = STF 2909 AB are recalculated because of significant deviations of more recent observations from the ephemerides. For binaries WDS 22384-0754 = A 2695, WDS 23474-7118 = FIN 375 Aa and WDS 23578+2508 = McA 76 the orbital elements are calculated for the first time.

  12. Quantum Effects on the Capacitance of Graphene-Based Electrodes

    SciTech Connect

    Zhan, Cheng; Neal, Justin; Wu, Jianzhong; Jiang, De-en

    2015-09-08

    We recently measured quantum capacitance for electric double layers (EDL) at electrolyte/graphene interfaces. However, the importance of quantum capacitance in realistic carbon electrodes is not clear. Toward understanding that from a theoretical perspective, here we studied the quantum capacitance and total capacitance of graphene electrodes as a function of the number of graphene layers. The quantum capacitance was obtained from electronic density functional theory based on fixed band approximation with an implicit solvation model, while the EDL capacitances were from classical density functional theory. We found that quantum capacitance plays a dominant role in total capacitance of the single-layer graphene both in aqueous and ionic-liquid electrolytes but the contribution decreases as the number of graphene layers increases. Moreover, the total integral capacitance roughly levels off and is dominated by the EDL capacitance beyond about four graphene layers. Finally, because many porous carbons have nanopores with stacked graphene layers at the surface, this research provides a good estimate of the effect of quantum capacitance on their electrochemical performance.

  13. Quantum Effects on the Capacitance of Graphene-Based Electrodes

    DOE PAGESBeta

    Zhan, Cheng; Neal, Justin; Wu, Jianzhong; Jiang, De-en

    2015-09-08

    We recently measured quantum capacitance for electric double layers (EDL) at electrolyte/graphene interfaces. However, the importance of quantum capacitance in realistic carbon electrodes is not clear. Toward understanding that from a theoretical perspective, here we studied the quantum capacitance and total capacitance of graphene electrodes as a function of the number of graphene layers. The quantum capacitance was obtained from electronic density functional theory based on fixed band approximation with an implicit solvation model, while the EDL capacitances were from classical density functional theory. We found that quantum capacitance plays a dominant role in total capacitance of the single-layer graphenemore » both in aqueous and ionic-liquid electrolytes but the contribution decreases as the number of graphene layers increases. Moreover, the total integral capacitance roughly levels off and is dominated by the EDL capacitance beyond about four graphene layers. Finally, because many porous carbons have nanopores with stacked graphene layers at the surface, this research provides a good estimate of the effect of quantum capacitance on their electrochemical performance.« less

  14. Membrane Capacitance Measurements Revisited: Dependence of Capacitance Value on Measurement Method in Nonisopotential Neurons

    PubMed Central

    Thomas, Gladis; Taylor, Adam L.; Patel, Arif; Pineda, Arlene; Khalil, Christopher; Nadim, Farzan

    2009-01-01

    During growth or degeneration neuronal surface area can change dramatically. Measurements of membrane protein concentration, as in ion channel or ionic conductance density, are often normalized by membrane capacitance, which is proportional to the surface area, to express changes independently from cell surface variations. Several electrophysiological protocols are used to measure cell capacitance, all based on the assumption of membrane isopotentiality. Yet, most neurons violate this assumption because of their complex anatomical structure, raising the question of which protocol yields measurements that are closest to the actual total membrane capacitance. We measured the capacitance of identified neurons from crab stomatogastric ganglia using three different protocols: the current-clamp step, the voltage-clamp step, and the voltage-clamp ramp protocols. We observed that the current-clamp protocol produced significantly higher capacitance values than those of either voltage-clamp protocol. Computational models of various anatomical complexities suggest that the current-clamp protocol can yield accurate capacitance estimates. In contrast, the voltage-clamp protocol estimates rapidly deteriorate as isopotentiality is reduced. We provide a mathematical description of these results by analyzing a simple two-compartment model neuron to facilitate an intuitive understanding of these methods. Together, the experiments, modeling, and mathematical analysis indicate that accurate total membrane capacitance measurements cannot be obtained with voltage-clamp protocols in nonisopotential neurons. Furthermore, although current-clamp steps can theoretically yield accurate measurements, experimentalists should be aware of limitations imposed by step duration and numerical errors during fitting procedures to obtain the membrane time constant. PMID:19571202

  15. Noncontact monitoring of cardiorespiratory activity by electromagnetic coupling.

    PubMed

    Teichmann, Daniel; Foussier, Jérôme; Jia, Jing; Leonhardt, Steffen; Walter, Marian

    2013-08-01

    In this paper, the method of noncontact monitoring of cardiorespiratory activity by electromagnetic coupling with human tissue is investigated. Two measurement modalities were joined: an inductive coupling sensor based on magnetic eddy current induction and a capacitive coupling sensor based on displacement current induction. The system's sensitivity to electric tissue properties and its dependence on motion are analyzed theoretically as well as experimentally for the inductive and capacitive coupling path. The potential of both coupling methods to assess respiration and pulse without contact and a minimum of thoracic wall motion was verified by laboratory experiments. The demonstrator was embedded in a chair to enable recording from the back part of the thorax.

  16. DC Pulsed Atmospheric Micro Plasma using a Voltage Doubled Capacitive Ballast

    NASA Astrophysics Data System (ADS)

    Ha, Chang-Seung; Lee, Je-Hyun; Son, Eui-Jeong; Kim, Dong-Hyun; Lee, Hae June; Lee, Ho-Jun; PPRC Team

    2013-09-01

    An atmospheric plasma driven by the capacitive ballast circuit with voltage doubler has been developed. At first, the capacitors are charged and then the stored energy is injected into the electrode. At that time, the voltage is doubled by means of series connection switching. The switching device isolate the power from the plasma, therefore the discharge energy is effectively controlled by the stored energy in the capacitor. The role of voltage doubler is maintaining the charging voltage less than the firing voltage of the electrodes and providing sufficiently high voltage during the plasma generation. It eliminates parasitic discharge due to capacitive coupling between isolation switch and plasma electrodes. Proposed method allows stable operation of the μ-plasma under dielectric-free electrode as well as independent control of discharge voltage and energy. When the applied capacitance is varied as 1.2 nF, 10 nF and 22 nF at the voltage of 600V, the corresponding discharge energy per pulse is 168 μJ, 971 μJ, and 1.126 mJ respectively. For the fixed capacitance value, discharge duration decreases and peak current increases with the discharge voltage. The characteristics of the micro plasma are analyzed in terms of time-resolved images, spatio-temporally resolved OES and fluid simulations. This research was supported by Basic Science Research Program through the National Research Foundation of Korea (NRF) funded by the Ministry of Education, Science and Technology (2010-0011136).

  17. A 0.9-V pulse frequency modulation photosensor based on capacitive feedback reset

    NASA Astrophysics Data System (ADS)

    Yasuoka, Koutaro; Kagawa, Keiichiro; Ohta, Jun; Nunoshita, Masahiro

    2005-03-01

    We are developing a retinal prosthesis vision chip based on a pulse-frequency-modulation (PFM) photosensor. Because the device is implanted in the eye ball and is powered by RF coil coupling with limited energy, low voltage and small current operation is required to achieve low power dissipation. We propose a capacitive-feedback-reset method for the PFM vision chip. The proposed method uses capacitive feed back through the junction capacitance of the photodiode and gate-source overlap capacitance of the reset transistor. In the proposed PFM circuit, the feed-through effect in resetting contributes to avoid current competition, so that the high dynamic range can be achieved even at the low voltage operation. We have fabricated a pixel TEG circuit in a 0.35-μm CMOS technology. The PFM photosensor circuit is composed of a four-stage inverter-chain. Dynamic range of 136dB has been achieved with 0.8-V power supply.

  18. A novel STM-assisted microwave microscope with capacitance and loss imaging capability.

    PubMed

    Imtiaz, Atif; Anlage, Steven M

    2003-04-01

    We report a new technique of scanning capacitance microscopy at microwave frequencies. A near field scanning microwave microscope probe is kept at a constant height of about 1 nm above the sample with the help of scanning tunneling microscope (STM) feedback. The microwaves are incident onto the sample through a coaxial resonator that is terminated at one end with a sharp tip (the same tip is used to conduct STM), and capacitively coupled to a feedback circuit and microwave source at the other end. The feedback circuit keeps the source locked onto the resonance frequency of the resonator and outputs the frequency shift and quality factor change due to property variations of the sample. The spatial resolution due to capacitance variations is congruent with 2.5 nm. The microwave microscope is sensitive to sample sheet resistance, as demonstrated through measurements on a doped silicon sample. We develop a quantitative transmission line model treating the tip to sample interaction as a series combination of capacitance and sheet resistance in the sample.

  19. Concentric-annulus electrical capacitance tomography sensors

    NASA Astrophysics Data System (ADS)

    Ye, Jiamin; Li, Yi; Wang, Haigang; Ge, Ruihuan; Yang, Wuqiang

    2013-09-01

    The aim of this research is to investigate the unique shape (concentric-annulus) electrical capacitance tomography (ECT) sensors. This is motivated by the desire to improve the contrast and spatial resolution of the images reconstructed using ECT sensors with internal-external electrodes (IEEs). Both numerical simulation and experimental study were carried out with the goal of providing an improved understanding of the configuration of IEE sensors, the internal shield and the measurement strategies. Simulation results are in agreement with the experimental results. Using the linear back projection algorithm, the IEE sensor with 12 external electrodes and 4 internal electrodes with the external-opposite-internal measurement strategy can reconstruct high-quality images. In experimental studies, the internal shield may reduce the quality of capacitance measured from the internal electrodes.

  20. Layer resolved capacitive probing of graphene bilayers

    NASA Astrophysics Data System (ADS)

    Zibrov, Alexander; Parmentier, François; Li, Jia; Wang, Lei; Hunt, Benjamin; Dean, Cory; Hone, James; Taniguchi, Takashi; Watanabe, Kenji; Young, Andrea

    Compared to single layer graphene, graphene bilayers have an additional ``which-layer'' degree of freedom that can be controlled by an external electric field in a dual-gated device geometry. We describe capacitance measurements capable of directly probing this degree of freedom. By performing top gate, bottom gate, and penetration field capacitance measurements, we directly extract layer polarization of both Bernal and twisted bilayers. We will present measurements of hBN encapsulated bilayers at both zero and high magnetic field, focusing on the physics of the highly degenerate zero-energy Landau level in the high magnetic field limit where spin, valley, and layer degeneracy are all lifted by electronic interactions.

  1. Compressed magnetic flux amplifier with capacitive load

    SciTech Connect

    Stuetzer, O.M.

    1980-03-01

    A first-order analysis is presented for a compressed magnetic flux (CMF) current amplifier working into a load with a capacitive component. Since the purpose of the investigation was to gain a general understanding of the arrangement, a number of approximations and limitations were accepted. The inductance of the transducer varies with time; the inductance/resistance/capacitance (LRC) circuit therefore is parametric and solutions are different for the stable regime (high C), the oscillation regime (low C), and the transition case. Solutions and performance depend strongly on circuit boundary conditions, i.e., energization of the circuit by either an injected current or by an applied capacitor charge. The behavior of current and energy amplification for the various cases are discussed in detail. A number of experiments with small CMF devices showed that the first-order theory presented predicts transducer performance well in the linear regime.

  2. Capacitance based mass metering for cryogenic fluids

    NASA Astrophysics Data System (ADS)

    Nurge, Mark A.; Youngquist, Robert; Walters, Deron

    2003-09-01

    This paper describes a method for measuring the mass of cryogenic fluids in on-board rocket propellant tanks or ground storage tanks. Linear approximations to the Clausius-Mossotti relationship serve as the foundation for a capacitance based mass sensor, regardless of fluid density stratification or tank shape. Sensor design considerations are presented along with the experimental results for a capacitance based mass gage tested in liquid nitrogen. This test data is shown to be consistent with theory resulting in a demonstrated mass measurement accuracy of ±0.75% and a deviation from linearity of less than ±0.30% of full scale mass. Theoretical accuracies are also shown to be ±0.73% for hydrogen and ±1.39% for oxygen for a select range of pressures and temperatures.

  3. Biochemical capacitance of Geobacter sulfurreducens biofilms.

    PubMed

    Bueno, Paulo R; Schrott, Germán D; Bonanni, Pablo S; Simison, Silvia N; Busalmen, Juan P

    2015-08-10

    An electrical model able to decouple the electron pathway from microbial cell machinery impedance terms is introduced. In this context, capacitance characteristics of the biofilm are clearly resolved. In other words, the model allows separating, according to the advantage of frequency and spectroscopic response approach, the different terms controlling the performance of the microbial biofilm respiratory process and thus the directly related electricity production process. The model can be accurately fitted to voltammetry measurements obtained under steady-state conditions and also to biofilm discharge amperometric measurements. The implications of biological aspects of the electrochemical or redox capacitance are discussed theoretically in the context of current knowledge with regard to structure and physiological activity of microbial Geobacter biofilms. PMID:26212121

  4. Ultra-High-Frequency Capacitive Displacement Sensor

    NASA Technical Reports Server (NTRS)

    Vanzandt, Thomas R.; Kenny, Thomas W.; Kaiser, William J.

    1994-01-01

    Improved class of compact, high-resolution capacitive displacement sensors operates at excitation frequency of 915 MHz and measures about 7.5 by 4 by 2 centimeters. Contains commercially available 915-MHz oscillator and transmission-line resonator. Resonator contains stripline inductor in addition to variable capacitor. Ultrahigh excitation frequency offers advantages of resolution and frequency response. Not deleteriously affected by mechanical overdriving, or contact between electrodes.

  5. Solar System binaries

    NASA Astrophysics Data System (ADS)

    Noll, Keith S.

    The discovery of binaries in each of the major populations of minor bodies in the solar system is propelling a rapid growth of heretofore unattainable physical information. The availability of mass and density constraints for minor bodies opens the door to studies of internal structure, comparisons with meteorite samples, and correlations between bulk-physical and surface-spectral properties. The number of known binaries is now more than 70 and is growing rapidly. A smaller number have had the extensive followup observations needed to derive mass and albedo information, but this list is growing as well. It will soon be the case that we will know more about the physical parameters of objects in the Kuiper Belt than has been known about asteroids in the Main Belt for the last 200 years. Another important aspect of binaries is understanding the mechanisms that lead to their formation and survival. The relative sizes and separations of binaries in the different minor body populations point to more than one mechanism for forming bound pairs. Collisions appear to play a major role in the Main Belt. Rotational and/or tidal fission may be important in the Near Earth population. For the Kuiper Belt, capture in multi-body interactions may be the preferred formation mechanism. However, all of these conclusions remain tentative and limited by observational and theoretical incompleteness. Observational techniques for identifying binaries are equally varied. High angular resolution observations from space and from the ground are critical for detection of the relatively distant binaries in the Main Belt and the Kuiper Belt. Radar has been the most productive method for detection of Near Earth binaries. Lightcurve analysis is an independent technique that is capable of exploring phase space inaccessible to direct observations. Finally, spacecraft flybys have played a crucial paradigm-changing role with discoveries that unlocked this now-burgeoning field.

  6. Carbon Materials for Chemical Capacitive Energy Storage

    SciTech Connect

    Zhai, Yunpu; Dou, Yuqian; Zhao, Dongyuan; Fulvio, Pasquale F.; Mayes, Richard T.; Dai, Sheng

    2011-09-26

    Carbon materials have attracted intense interests as electrode materials for electrochemical capacitors, because of their high surface area, electrical conductivity, chemical stability and low cost. Activated carbons produced by different activation processes from various precursors are the most widely used electrodes. Recently, with the rapid growth of nanotechnology, nanostructured electrode materials, such as carbon nanotubes and template-synthesized porous carbons have been developed. Their unique electrical properties and well controlled pore sizes and structures facilitate fast ion and electron transportation. In order to further improve the power and energy densities of the capacitors, carbon-based composites combining electrical double layer capacitors (EDLC)-capacitance and pseudo-capacitance have been explored. They show not only enhanced capacitance, but as well good cyclability. In this review, recent progresses on carbon-based electrode materials are summarized, including activated carbons, carbon nanotubes, and template-synthesized porous carbons, in particular mesoporous carbons. Their advantages and disadvantages as electrochemical capacitors are discussed. At the end of this review, the future trends of electrochemical capacitors with high energy and power are proposed.

  7. Carbon materials for chemical capacitive energy storage.

    PubMed

    Zhai, Yunpu; Dou, Yuqian; Zhao, Dongyuan; Fulvio, Pasquale F; Mayes, Richard T; Dai, Sheng

    2011-11-01

    Carbon materials have attracted intense interests as electrode materials for electrochemical capacitors, because of their high surface area, electrical conductivity, chemical stability and low cost. Activated carbons produced by different activation processes from various precursors are the most widely used electrodes. Recently, with the rapid growth of nanotechnology, nanostructured electrode materials, such as carbon nanotubes and template-synthesized porous carbons have been developed. Their unique electrical properties and well controlled pore sizes and structures facilitate fast ion and electron transportation. In order to further improve the power and energy densities of the capacitors, carbon-based composites combining electrical double layer capacitors (EDLC)-capacitance and pseudo-capacitance have been explored. They show not only enhanced capacitance, but as well good cyclability. In this review, recent progresses on carbon-based electrode materials are summarized, including activated carbons, carbon nanotubes, and template-synthesized porous carbons, in particular mesoporous carbons. Their advantages and disadvantages as electrochemical capacitors are discussed. At the end of this review, the future trends of electrochemical capacitors with high energy and power are proposed. PMID:21953940

  8. Evaluation of EHD films by electrical capacitance

    NASA Astrophysics Data System (ADS)

    Jablonka, Karolina; Glovnea, Romeo; Bongaerts, Jeroen

    2012-09-01

    The elastohydrodynamic (EHD) lubrication regime occurs in many machine elements where a combination of hydrodynamic effect, elastic deformation of the loaded surfaces and increase in the viscosity of the lubricant with pressure ensures the formation of a very thin, but continuous film of lubricant separating the contacting surfaces. Electrical methods to determine this film's thickness have preceded optical methods, which are widely used today. Although they generally give more qualitative thickness information, electrical methods have the main advantage that they can be applied to metallic contacts in machines, which makes them useful tools in the study of elastohydrodynamically lubricated contacts. This paper is part of a larger study on the application of electrical capacitance for the evaluation of film formation in EHD contacts. The main focus is on the quantitative measurements of film thickness using electrical capacitance. A new approach allowing the lubricant film thickness to be extracted from the measured capacitance is developed using a chromium-coated glass disc and subsequently applied to a steel-on-steel contact. The results show good agreement with optical measurements and theoretical models over a range of film thickness.

  9. Effect of Astaxanthin on Human Sperm Capacitation

    PubMed Central

    Donà, Gabriella; Kožuh, Ivana; Brunati, Anna Maria; Andrisani, Alessandra; Ambrosini, Guido; Bonanni, Guglielmo; Ragazzi, Eugenio; Armanini, Decio; Clari, Giulio; Bordin, Luciana

    2013-01-01

    In order to be able to fertilize oocytes, human sperm must undergo a series of morphological and structural alterations, known as capacitation. It has been shown that the production of endogenous sperm reactive oxygen species (ROS) plays a key role in causing cells to undergo a massive acrosome reaction (AR). Astaxanthin (Asta), a photo-protective red pigment belonging to the carotenoid family, is recognized as having anti-oxidant, anti-cancer, anti-diabetic and anti-inflammatory properties and is present in many dietary supplements. This study evaluates the effect of Asta in a capacitating buffer which induces low ROS production and low percentages of acrosome-reacted cells (ARC). Sperm cells were incubated in the presence or absence of increasing concentrations of Asta or diamide (Diam) and analyzed for their ROS production, Tyr-phosphorylation (Tyr-P) pattern and percentages of ARC and non-viable cells (NVC). Results show that Asta ameliorated both sperm head Tyr-P and ARC values without affecting the ROS generation curve, whereas Diam succeeded in enhancing the Tyr-P level but only of the flagellum without increasing ARC values. It is suggested that Asta can be inserted in the membrane and therefore create capacitation-like membrane alteration which allow Tyr-P of the head. Once this has occurred, AR can take place and involves a higher numbers of cells. PMID:23736766

  10. Effect of astaxanthin on human sperm capacitation.

    PubMed

    Donà, Gabriella; Kožuh, Ivana; Brunati, Anna Maria; Andrisani, Alessandra; Ambrosini, Guido; Bonanni, Guglielmo; Ragazzi, Eugenio; Armanini, Decio; Clari, Giulio; Bordin, Luciana

    2013-06-01

    In order to be able to fertilize oocytes, human sperm must undergo a series of morphological and structural alterations, known as capacitation. It has been shown that the production of endogenous sperm reactive oxygen species (ROS) plays a key role in causing cells to undergo a massive acrosome reaction (AR). Astaxanthin (Asta), a photo-protective red pigment belonging to the carotenoid family, is recognized as having anti-oxidant, anti-cancer, anti-diabetic and anti-inflammatory properties and is present in many dietary supplements. This study evaluates the effect of Asta in a capacitating buffer which induces low ROS production and low percentages of acrosome-reacted cells (ARC). Sperm cells were incubated in the presence or absence of increasing concentrations of Asta or diamide (Diam) and analyzed for their ROS production, Tyr-phosphorylation (Tyr-P) pattern and percentages of ARC and non-viable cells (NVC). Results show that Asta ameliorated both sperm head Tyr-P and ARC values without affecting the ROS generation curve, whereas Diam succeeded in enhancing the Tyr-P level but only of the flagellum without increasing ARC values. It is suggested that Asta can be inserted in the membrane and therefore create capacitation-like membrane alteration which allow Tyr-P of the head. Once this has occurred, AR can take place and involves a higher numbers of cells. PMID:23736766

  11. Carbon materials for chemical capacitive energy storage.

    PubMed

    Zhai, Yunpu; Dou, Yuqian; Zhao, Dongyuan; Fulvio, Pasquale F; Mayes, Richard T; Dai, Sheng

    2011-11-01

    Carbon materials have attracted intense interests as electrode materials for electrochemical capacitors, because of their high surface area, electrical conductivity, chemical stability and low cost. Activated carbons produced by different activation processes from various precursors are the most widely used electrodes. Recently, with the rapid growth of nanotechnology, nanostructured electrode materials, such as carbon nanotubes and template-synthesized porous carbons have been developed. Their unique electrical properties and well controlled pore sizes and structures facilitate fast ion and electron transportation. In order to further improve the power and energy densities of the capacitors, carbon-based composites combining electrical double layer capacitors (EDLC)-capacitance and pseudo-capacitance have been explored. They show not only enhanced capacitance, but as well good cyclability. In this review, recent progresses on carbon-based electrode materials are summarized, including activated carbons, carbon nanotubes, and template-synthesized porous carbons, in particular mesoporous carbons. Their advantages and disadvantages as electrochemical capacitors are discussed. At the end of this review, the future trends of electrochemical capacitors with high energy and power are proposed.

  12. Milankovitch Cycles of Terrestrial Planets in Binary Star Systems

    NASA Astrophysics Data System (ADS)

    Forgan, Duncan

    2016-08-01

    The habitability of planets in binary star systems depends not only on the radiation environment created by the two stars, but also on the perturbations to planetary orbits and rotation produced by the gravitational field of the binary and neighbouring planets. Habitable planets in binaries may therefore experience significant perturbations in orbit and spin. The direct effects of orbital resonances and secular evolution on the climate of binary planets remain largely unconsidered. We present latitudinal energy balance modelling of exoplanet climates with direct coupling to an N Body integrator and an obliquity evolution model. This allows us to simultaneously investigate the thermal and dynamical evolution of planets orbiting binary stars, and discover gravito-climatic oscillations on dynamical and secular timescales. We investigate the Kepler-47 and Alpha Centauri systems as archetypes of P and S type binary systems respectively. In the first case, Earthlike planets would experience rapid Milankovitch cycles (of order 1000 years) in eccentricity, obliquity and precession, inducing temperature oscillations of similar periods (modulated by other planets in the system). These secular temperature variations have amplitudes similar to those induced on the much shorter timescale of the binary period. In the Alpha Centauri system, the influence of the secondary produces eccentricity variations on 15,000 year timescales. This produces climate oscillations of similar strength to the variation on the orbital timescale of the binary. Phase drifts between eccentricity and obliquity oscillations creates further cycles that are of order 100,000 years in duration, which are further modulated by neighbouring planets.

  13. Kepler's Cool Eclipsing Binaries

    NASA Astrophysics Data System (ADS)

    Swift, Jonathan; Muirhead, P. S.; Johnson, J. A.; Gonzales, A.; Shporer, A.; Plavchan, P.; Lockwood, A.; Morton, T.

    2014-01-01

    Some of the most exciting exoplanet results to date have come from the smallest and coolest sample of stars in the Kepler field—the M dwarfs. These cool stars represent the largest stellar population in the Galaxy which in turn harbors one of the largest known exoplanet populations. However, an accurate understanding of their physical properties currently eludes us. Detached, M dwarf eclipsing binary systems provide an accurate and precise, model-independent means of measuring the fundamental properties of low-mass stars shedding light on the rich physics embodied by this spectral class and refining our knowledge of their exoplanets. We have undertaken an observational campaign to obtain masses, radii, and effective temperatures of the Kepler eclipsing binaries having an M dwarf primary with periods between 1 and 60 days. These data will allow detailed comparisons between stellar properties, binary period, rotation, metallicity and activity levels.

  14. Binary ferrihydrite catalysts

    DOEpatents

    Huffman, Gerald P.; Zhao, Jianmin; Feng, Zhen

    1996-01-01

    A method of preparing a catalyst precursor comprises dissolving an iron salt and a salt of an oxoanion forming agent, in water so that a solution of the iron salt and oxoanion forming agent salt has a ratio of oxoanion/Fe of between 0.0001:1 to 0.5:1. Next is increasing the pH of the solution to 10 by adding a strong base followed by collecting of precipitate having a binary ferrihydrite structure. A binary ferrihydrite catalyst precursor is also prepared by dissolving an iron salt in water. The solution is brought to a pH of substantially 10 to obtain ferrihydrite precipitate. The precipitate is then filtered and washed with distilled water and subsequently admixed with a hydroxy carboxylic acid solution. The admixture is mixed/agitated and the binary ferrihydrite precipitate is then filtered and recovered.

  15. Binary ferrihydrite catalysts

    DOEpatents

    Huffman, G.P.; Zhao, J.; Feng, Z.

    1996-12-03

    A method of preparing a catalyst precursor comprises dissolving an iron salt and a salt of an oxoanion forming agent, in water so that a solution of the iron salt and oxoanion forming agent salt has a ratio of oxoanion/Fe of between 0.0001:1 to 0.5:1. Next is increasing the pH of the solution to 10 by adding a strong base followed by collecting of precipitate having a binary ferrihydrite structure. A binary ferrihydrite catalyst precursor is also prepared by dissolving an iron salt in water. The solution is brought to a pH of substantially 10 to obtain ferrihydrite precipitate. The precipitate is then filtered and washed with distilled water and subsequently admixed with a hydroxy carboxylic acid solution. The admixture is mixed/agitated and the binary ferrihydrite precipitate is then filtered and recovered. 3 figs.

  16. The compressibility and the capacitance coefficient of helium-oxygen atmospheres.

    PubMed

    Imbert, G; Dejours, P; Hildwein, G

    1982-12-01

    The capacitance coefficient beta of an ideal gas mixture depends only on its temperature T, and its value is derived from the ideal gas law (i.e., beta = 1/RT, R being the ideal gas constant). But real gases behave as ideal gases only at low pressures, and this would not be the case in deep diving. High pressures of helium-oxygen are used in human and animal experimental dives (up to 7 or 12 MPa or more, respectively). At such pressures deviations from the ideal gas law cannot be neglected in hyperbaric atmospheres with respect to current accuracy of measuring instruments. As shown both theoretically and experimentally by this study, the non-ideal nature of helium-oxygen has a significant effect on the capacitance coefficient of hyperbaric atmospheres. The theoretical study is based on interaction energy in either homogeneous (He-He and O2-O2) or heterogeneous (He-O2) molecular pairs, and on the virial equation of state for gas mixtures. The experimental study is based on weight determination of samples of known volume of binary helium-oxygen mixtures, which are prepared in well-controlled pressure and temperature conditions. Our experimental results are in good agreement with theoretical predictions. 1) The helium compressibility factor ZHe increases linearly with pressure [ZHe = 1 + 0.0045 P (in MPa) at 30 degrees C]; and 2) in same temperature and pressure conditions (T = 303 K and P = 0.1 to 15 MPa), the same value for Z is valid for a helium-oxygen binary mixture and for pure helium. As derived from the equation of state of real gases, the capacitance coefficient is inversely related to Z (beta = 1/ZRT); therefore, for helium-oxygen mixtures, this coefficient would decrease with increasing pressure. A table is given for theoretical values of helium-oxygen capacitance coefficient, at pressures ranging from 0.1 to 15.0 MPa and at temperatures ranging from 25 degrees C to 37 degrees C. PMID:7168095

  17. Binary Oscillatory Crossflow Electrophoresis

    NASA Technical Reports Server (NTRS)

    Molloy, Richard F.; Gallagher, Christopher T.; Leighton, David T., Jr.

    1996-01-01

    We present preliminary results of our implementation of a novel electrophoresis separation technique: Binary Oscillatory Cross flow Electrophoresis (BOCE). The technique utilizes the interaction of two driving forces, an oscillatory electric field and an oscillatory shear flow, to create an active binary filter for the separation of charged species. Analytical and numerical studies have indicated that this technique is capable of separating proteins with electrophoretic mobilities differing by less than 10%. With an experimental device containing a separation chamber 20 cm long, 5 cm wide, and 1 mm thick, an order of magnitude increase in throughput over commercially available electrophoresis devices is theoretically possible.

  18. Identification list of binaries

    NASA Astrophysics Data System (ADS)

    Malkov,, O.; Karchevsky,, A.; Kaygorodov, P.; Kovaleva, D.

    The Identification List of Binaries (ILB) is a star catalogue constructed to facilitate cross-referencing between different catalogues of binary stars. As of 2015, it comprises designations for approximately 120,000 double/multiple systems. ILB contains star coordinates and cross-references to the Bayer/Flemsteed, DM (BD/CD/CPD), HD, HIP, ADS, WDS, CCDM, TDSC, GCVS, SBC9, IGR (and some other X-ray catalogues), PSR designations, as well as identifications in the recently developed BSDB system. ILB eventually became a part of the BDB stellar database.

  19. Novel on-line column extraction apparatus coupled with binary peak focusing for high-performance liquid chromatography determination of rifampicin in human plasma: a strategy for therapeutic drug monitoring.

    PubMed

    Li, Wei; Peng, Min; Long, Minghui; Qiu, Ximin; Yang, Liping

    2014-12-01

    In order to develop a method that is completely suitable for the routine therapeutic drug monitoring, a sensitive and fully automated on-line column extraction apparatus in combination with high-performance liquid chromatography allowing binary peak focusing was developed and validated for the determination of rifampicin in human plasma. Rifapentine was used as an internal standard. The analytical cycle started with the injection of 100 μL of the sample pretreated by protein precipitation in a Venusil SCX extraction column. After the elution, the analytes were transferred and concentrated in an Xtimate C18 trap column. Finally, the trapped analytes were separated by an Xtimate C18 analytical column and were analyzed by an ultraviolet detector at 336 nm. With this new strategy, continuous on-line analysis of the compounds was successfully performed. The method showed excellent performance for the analysis of rifampicin in plasma samples, including calibration curve linearity (All r were larger than 0.9996), sensitivity (lowest limit of quantification was 0.12 μg/mL), method accuracy (within 6.6% in terms of relative error), and precision (relative standard deviations of intra- and interday precision were less than 7.8%). These results demonstrated that the simple, reliable, and automatic method based on on-line column extraction and binary peak focusing is a promising approach for therapeutic drug monitoring in complex biomatrix samples.

  20. Direct writing on paper of foldable capacitive touch pads with silver nanowire inks.

    PubMed

    Li, Ruo-Zhou; Hu, Anming; Zhang, Tong; Oakes, Ken D

    2014-12-10

    Paper-based capacitive touch pads can be fabricated utilizing high-concentration silver nanowire inks needle-printed directly onto paper substrates through a 2D programmable platform. Post deposition, silver nanowire tracks can be photonically sintered using a camera flash to reduce sheet resistance similar to thermal sintering approaches. Touch pad sensors on a variety of paper substrates can be achieved with optimized silver nanowire tracks. Rolling and folding trials, which yielded only modest changes in capacitance and no loss of function, coupled with touch pad functionality on curved surfaces, suggest sufficient flexibility and durability for paper substrate touch pads to be used in diverse applications. A simplified model to predict touch pad capacitance variation ranges with differing touch conditions was developed, with good agreement against experimental results. Such paper-based touch pads have the advantage of simple structure, easy fabrication, and fast sintering, which holds promise for numerous commercial applications including low-cost portable devices where ultrathin and lightweight features, coupled with reliable bending stability are desirable.

  1. Micropower non-contact EEG electrode with active common-mode noise suppression and input capacitance cancellation.

    PubMed

    Chi, Yu M; Cauwenberghs, Gert

    2009-01-01

    A non-contact EEG electrode with input capacitance neutralization and common-mode noise suppression circuits is presented. The coin sized sensor capacitively couples to the scalp without direct contact to the skin. To minimize the effect of signal attenuation and channel gain mismatch, the input capacitance of each sensor is actively neutralized using positive feedback and bootstrapping. Common-mode suppression is achieved through a single conductive sheet to establish a common mode reference. Each sensor electrode provides a differential gain of 60 dB. Signals are transmitted in a digital serial daisy-chain directly from a local 16-bit ADC, minimizing the number of wires required to establish a high density EEG sensor network. The micropower electrode consumes only 600 microW from a single 3.3 V supply.

  2. Binary coding for hyperspectral imagery

    NASA Astrophysics Data System (ADS)

    Wang, Jing; Chang, Chein-I.; Chang, Chein-Chi; Lin, Chinsu

    2004-10-01

    Binary coding is one of simplest ways to characterize spectral features. One commonly used method is a binary coding-based image software system, called Spectral Analysis Manager (SPAM) for remotely sensed imagery developed by Mazer et al. For a given spectral signature, the SPAM calculates its spectral mean and inter-band spectral difference and uses them as thresholds to generate a binary code word for this particular spectral signature. Such coding scheme is generally effective and also very simple to implement. This paper revisits the SPAM and further develops three new SPAM-based binary coding methods, called equal probability partition (EPP) binary coding, halfway partition (HP) binary coding and median partition (MP) binary coding. These three binary coding methods along with the SPAM well be evaluated for spectral discrimination and identification. In doing so, a new criterion, called a posteriori discrimination probability (APDP) is also introduced for performance measure.

  3. N-Bit Binary Resistor

    NASA Technical Reports Server (NTRS)

    Tcheng, Ping

    1989-01-01

    Binary resistors in series tailored to precise value of resistance. Desired value of resistance obtained by cutting appropriate traces across resistors. Multibit, binary-based, adjustable resistor with high resolution used in many applications where precise resistance required.

  4. CMOS MEMS capacitive absolute pressure sensor

    NASA Astrophysics Data System (ADS)

    Narducci, M.; Yu-Chia, L.; Fang, W.; Tsai, J.

    2013-05-01

    This paper presents the design, fabrication and characterization of a capacitive pressure sensor using a commercial 0.18 µm CMOS (complementary metal-oxide-semiconductor) process and postprocess. The pressure sensor is capacitive and the structure is formed by an Al top electrode enclosed in a suspended SiO2 membrane, which acts as a movable electrode against a bottom or stationary Al electrode fixed on the SiO2 substrate. Both the movable and fixed electrodes form a variable parallel plate capacitor, whose capacitance varies with the applied pressure on the surface. In order to release the membranes the CMOS layers need to be applied postprocess and this mainly consists of four steps: (1) deposition and patterning of PECVD (plasma-enhanced chemical vapor deposition) oxide to protect CMOS pads and to open the pressure sensor top surface, (2) etching of the sacrificial layer to release the suspended membrane, (3) deposition of PECVD oxide to seal the etching holes and creating vacuum inside the gap, and finally (4) etching of the passivation oxide to open the pads and allow electrical connections. This sensor design and fabrication is suitable to obey the design rules of a CMOS foundry and since it only uses low-temperature processes, it allows monolithic integration with other types of CMOS compatible sensors and IC (integrated circuit) interface on a single chip. Experimental results showed that the pressure sensor has a highly linear sensitivity of 0.14 fF kPa-1 in the pressure range of 0-300 kPa.

  5. Study the Z-Plane Strip Capacitance

    SciTech Connect

    Parikh, H.; Swain, S.; /SLAC

    2005-12-15

    The BaBaR detector at the Stanford Linear Accelerator Center is currently undergoing an upgrade to improve its muon and neutral hadron detection system. The Resistive Plate Chambers (RPCs) that had been used till now have deteriorated in performance over the past few years and are being replaced by Limited Streamer Tube (LSTs). Each layer of the system consists of a set of up to 10 streamer tube modules which provide one coordinate ({phi} coordinate) and a single ''Z-plane'' which provides the Z coordinate of the hit. The large area Z-planes (up to 12m{sup 2}) are 1mm thick and contain 96 copper strips that detect the induced charge from avalanches created in the streamer tube wires. All the Z-planes needed for the upgrade have already been constructed, but only a third of the planes were installed last summer. After installing the 24 Z-planes last year, it was learned that 0.7% of the strips were dead when put inside the detector. This was mainly due to the delicate solder joint between the read-out cable and the strip, and since it is difficult to access or replace the Z-planes inside the detector, it is very important to perform various tests to make sure that the Z-planes will be efficient and effective in the long term. We measure the capacitance between the copper strips and the ground plane, and compare it to the theoretical value that we expect. Instead of measuring the capacitance channel by channel, which would be a very tedious job, we developed a more effective method of measuring the capacitance. Since all the Z-planes were built at SLAC, we also built a smaller 46 cm by 30 cm Z-plane with 12 strips just to see how they were constructed and to gain a better understanding about the solder joints.

  6. Using an injection signal to reduce motion artifacts in capacitive ECG measurements.

    PubMed

    Serteyn, Aline; Vullings, Rik; Meftah, Mohammed; Bergmans, Jan

    2013-01-01

    Capacitive electrodes are a promising alternative to the conventional adhesive ECG electrodes. They provide more comfort to the patient when integrated in everyday objects (e.g. beds or seats) for long-term monitoring. However, the application of such electrodes is limited by their high sensitivity to motion artifacts. Artifacts caused by variation of the coupling capacitance are studied here. An injection signal is proposed to track these variations in real-time. An adaptive filter then estimates the motion artifact and cancels it from the recorded ECG. The amplitude of the motion artifact is reduced in average by 29 dB in simulation and by 20 dB in a lab environment. Our method has the advantages that it is able to reduce motion artifacts occurring in the frequency band of the ECG and that it does not require knowledge about the measurement system.

  7. Electromagnetic effects in high-frequency large-area capacitive discharges: A review

    SciTech Connect

    Liu, Yong-Xin; Zhang, Yu-Ru; Wang, You-Nian; Bogaerts, Annemie

    2015-03-15

    In traditional capacitively coupled plasmas, the discharge can be described by an electrostatic model, in which the Poisson equation is employed to determine the electrostatic electric field. However, current plasma reactors are much larger and driven at a much higher frequency. If the excitation wavelength λ in the plasma becomes comparable to the electrode radius, and the plasma skin depth δ becomes comparable to the electrode spacing, the electromagnetic (EM) effects will become significant and compromise the plasma uniformity. In this regime, capacitive discharges have to be described by an EM model, i.e., the full set of Maxwell's equations should be solved to address the EM effects. This paper gives an overview of the theory, simulation and experiments that have recently been carried out to understand these effects, which cause major uniformity problems in plasma processing for microelectronics and flat panel display industries. Furthermore, some methods for improving the plasma uniformity are also described and compared.

  8. A microfabricated fringing field capacitive pH sensor with an integrated readout circuit

    SciTech Connect

    Arefin, Md Shamsul Redoute, Jean-Michel; Rasit Yuce, Mehmet; Bulut Coskun, M.; Alan, Tuncay; Neild, Adrian

    2014-06-02

    This work presents a microfabricated fringe-field capacitive pH sensor using interdigitated electrodes and an integrated modulation-based readout circuit. The changes in capacitance of the sensor result from the permittivity changes due to pH variations and are converted to frequency shifts using a crossed-coupled voltage controlled oscillator readout circuit. The shift in resonant frequency of the readout circuit is 30.96 MHz for a change in pH of 1.0–5.0. The sensor can be used for the measurement of low pH levels, such as gastric acid, and can be integrated with electronic pills. The measurement results show high repeatability, low noise, and a stable output.

  9. Binary stars - Formation by fragmentation

    NASA Technical Reports Server (NTRS)

    Boss, Alan P.

    1988-01-01

    Theories of binary star formation by capture, separate nuclei, fission and fragmentation are compared, assessing the success of theoretical attempts to explain the observed properties of main-sequence binary stars. The theory of formation by fragmentation is examined, discussing the prospects for checking the theory against observations of binary premain-sequence stars. It is concluded that formation by fragmentation is successful at explaining many of the key properties of main-sequence binary stars.

  10. 3-D capacitance density imaging system

    DOEpatents

    Fasching, G.E.

    1988-03-18

    A three-dimensional capacitance density imaging of a gasified bed or the like in a containment vessel is achieved using a plurality of electrodes provided circumferentially about the bed in levels and along the bed in channels. The electrodes are individually and selectively excited electrically at each level to produce a plurality of current flux field patterns generated in the bed at each level. The current flux field patterns are suitably sensed and a density pattern of the bed at each level determined. By combining the determined density patterns at each level, a three-dimensional density image of the bed is achieved. 7 figs.

  11. Separation in Binary Alloys

    NASA Technical Reports Server (NTRS)

    Frazier, D. O.; Facemire, B. R.; Kaukler, W. F.; Witherow, W. K.; Fanning, U.

    1986-01-01

    Studies of monotectic alloys and alloy analogs reviewed. Report surveys research on liquid/liquid and solid/liquid separation in binary monotectic alloys. Emphasizes separation processes in low gravity, such as in outer space or in free fall in drop towers. Advances in methods of controlling separation in experiments highlighted.

  12. The Australian saltwater crocodile (Crocodylus porosus) provides evidence that the capacitation of spermatozoa may extend beyond the mammalian lineage.

    PubMed

    Nixon, Brett; Anderson, Amanda L; Smith, Nathan D; McLeod, Robby; Johnston, Stephen D

    2016-05-11

    Although mammalian spermatozoa only acquire functional maturity as they are conveyed through the male (epididymal maturation) and female (capacitation) reproductive tracts, the degree of post-testicular development necessary to achieve fertilization in other vertebrate species remains far less clear. Indeed, despite reports that the epididymis of birds and reptiles is capable of secreting proteins that bind and modify the sperm surface characteristics, it remains unclear whether capacitation is a pre-requisite for fertilization in these species. Using the ancient reptilian Australian saltwater crocodile as a model, this study was undertaken to explore whether reptile sperm do undergo capacitation-like changes following ejaculation. Our studies revealed that crocodile spermatozoa experienced a rapid and sustained, cyclic-AMP mediated increase in progressive motility following incubation under conditions optimized for the induction of capacitation in mammalian species such as the mouse and human. This response was coupled with elevated levels of phosphorylation associated with both protein kinase A and tyrosine kinase substrates, the latter of which were predominantly localized within the sperm flagellum. In findings that also accord with mammalian spermatozoa, we confirmed a homologue of outer dense fibre 2 as one of the principal substrates for tyrosine phosphorylation. Overall, our findings support the concept that crocodile spermatozoa do undergo a process that is homologous to capacitation in preparation for fertilization of an ovum. PMID:27147099

  13. Current dependence of base-collector capacitance of bipolar transistors

    NASA Astrophysics Data System (ADS)

    Liu, William; Harris, James S.

    1992-08-01

    We present analytical expressions for the base-collector capacitance of bipolar transistors in three operating conditions as the collector current density is continuously increased until the collector is fully depleted. A simple model is also presented to calculate this capacitance after base pushout occurs. The critical current densities separating each operating condition are discussed. The capacitance as a function of current density is calculated for various base-collector biases, collector thicknesses and collector dopings. The calculated results of this simple base-collector capacitance model are in close agreement with SEDAN simulation results. In addition, these results are shown to agree with published experimental work.

  14. Optimization of polyhydroxyalkanoates fermentations with on-line capacitance measurement.

    PubMed

    Li, Lan; Wang, Ze-Jian; Chen, Xue-Jun; Chu, Ju; Zhuang, Ying-Ping; Zhang, Si-Liang

    2014-03-01

    The aim of this work was to provide an effective methodology for optimization of the polyhydroxyalkanoates (PHAs) fermentation with Ralstonia eutropha by the on-line capacitance measurement. The present study found the capacitance values could reflect variations of microbial morphology and viability. Furthermore, oxygen uptake rate, specific oxygen uptake rate and specific growth rate were measured in real-time and compared with the capacitance value. In addition, a fed-batch control strategy based on the on-line capacitance measurement was proposed to improve the PHAs production by 22%.

  15. Variable-capacitance tachometer eliminates troublesome magnetic fields

    NASA Technical Reports Server (NTRS)

    1966-01-01

    Dual variable-capacitance tachometer measures angular speed and sense of rotation without magnetic components. Thus it eliminates magnetic flux interference with associated instrumentation in an electromechanical system.

  16. Quantum capacitance of graphene in contact with metal

    SciTech Connect

    Chang, Jin Hyun Dawson, Francis; Huzayyin, Ahmed; Lian, Keryn

    2015-11-09

    We report a versatile computation method to quantitatively determine the quantum capacitance of graphene when it is in contact with metal. Our results bridge the longstanding gap between the theoretically predicted and experimentally measured quantum capacitance of graphene. Contrary to popular assumptions, the presence of charged impurities or structural distortions of graphene are not the only sources of the asymmetric capacitance with respect to the polarity of the bias potential and the higher-than-expected capacitance at the Dirac point. They also originate from the field-induced electronic interactions between graphene and metal. We also provide an improved model representation of a metal–graphene junction.

  17. Brain-computer interfaces using capacitive measurement of visual or auditory steady-state responses

    NASA Astrophysics Data System (ADS)

    Baek, Hyun Jae; Kim, Hyun Seok; Heo, Jeong; Lim, Yong Gyu; Park, Kwang Suk

    2013-04-01

    Objective. Brain-computer interface (BCI) technologies have been intensely studied to provide alternative communication tools entirely independent of neuromuscular activities. Current BCI technologies use electroencephalogram (EEG) acquisition methods that require unpleasant gel injections, impractical preparations and clean-up procedures. The next generation of BCI technologies requires practical, user-friendly, nonintrusive EEG platforms in order to facilitate the application of laboratory work in real-world settings. Approach. A capacitive electrode that does not require an electrolytic gel or direct electrode-scalp contact is a potential alternative to the conventional wet electrode in future BCI systems. We have proposed a new capacitive EEG electrode that contains a conductive polymer-sensing surface, which enhances electrode performance. This paper presents results from five subjects who exhibited visual or auditory steady-state responses according to BCI using these new capacitive electrodes. The steady-state visual evoked potential (SSVEP) spelling system and the auditory steady-state response (ASSR) binary decision system were employed. Main results. Offline tests demonstrated BCI performance high enough to be used in a BCI system (accuracy: 95.2%, ITR: 19.91 bpm for SSVEP BCI (6 s), accuracy: 82.6%, ITR: 1.48 bpm for ASSR BCI (14 s)) with the analysis time being slightly longer than that when wet electrodes were employed with the same BCI system (accuracy: 91.2%, ITR: 25.79 bpm for SSVEP BCI (4 s), accuracy: 81.3%, ITR: 1.57 bpm for ASSR BCI (12 s)). Subjects performed online BCI under the SSVEP paradigm in copy spelling mode and under the ASSR paradigm in selective attention mode with a mean information transfer rate (ITR) of 17.78 ± 2.08 and 0.7 ± 0.24 bpm, respectively. Significance. The results of these experiments demonstrate the feasibility of using our capacitive EEG electrode in BCI systems. This capacitive electrode may become a flexible and

  18. A quintuple star system containing two eclipsing binaries

    NASA Astrophysics Data System (ADS)

    Rappaport, S.; Lehmann, H.; Kalomeni, B.; Borkovits, T.; Latham, D.; Bieryla, A.; Ngo, H.; Mawet, D.; Howell, S.; Horch, E.; Jacobs, T. L.; LaCourse, D.; Sódor, Á.; Vanderburg, A.; Pavlovski, K.

    2016-10-01

    We present a quintuple star system that contains two eclipsing binaries. The unusual architecture includes two stellar images separated by 11 arcsec on the sky: EPIC 212651213 and EPIC 212651234. The more easterly image (212651213) actually hosts both eclipsing binaries which are resolved within that image at 0.09 arcsec, while the westerly image (212651234) appears to be single in adaptive optics (AO), speckle imaging, and radial velocity (RV) studies. The `A' binary is circular with a 5.1-d period, while the `B' binary is eccentric with a 13.1-d period. The γ velocities of the A and B binaries are different by ˜10 km s-1. That, coupled with their resolved projected separation of 0.09 arcsec, indicates that the orbital period and separation of the `C' binary (consisting of A orbiting B) are ≃65 yr and ≃25 au, respectively, under the simplifying assumption of a circular orbit. Motion within the C orbit should be discernible via future RV, AO, and speckle imaging studies within a couple of years. The C system (i.e. 212651213) has an RV and proper motion that differ from that of 212651234 by only ˜1.4 km s-1 and ˜3 mas yr-1. This set of similar space velocities in three dimensions strongly implies that these two objects are also physically bound, making this at least a quintuple star system.

  19. Defragged Binary I Ching Genetic Code Chromosomes Compared to Nirenberg’s and Transformed into Rotating 2D Circles and Squares and into a 3D 100% Symmetrical Tetrahedron Coupled to a Functional One to Discern Start From Non-Start Methionines through a Stella Octangula

    PubMed Central

    Castro-Chavez, Fernando

    2012-01-01

    Background Three binary representations of the genetic code according to the ancient I Ching of Fu-Xi will be presented, depending on their defragging capabilities by pairing based on three biochemical properties of the nucleic acids: H-bonds, Purine/Pyrimidine rings, and the Keto-enol/Amino-imino tautomerism, yielding the last pair a 32/32 single-strand self-annealed genetic code and I Ching tables. Methods Our working tool is the ancient binary I Ching's resulting genetic code chromosomes defragged by vertical and by horizontal pairing, reverse engineered into non-binaries of 2D rotating 4×4×4 circles and 8×8 squares and into one 3D 100% symmetrical 16×4 tetrahedron coupled to a functional tetrahedron with apical signaling and central hydrophobicity (codon formula: 4[1(1)+1(3)+1(4)+4(2)]; 5:5, 6:6 in man) forming a stella octangula, and compared to Nirenberg's 16×4 codon table (1965) pairing the first two nucleotides of the 64 codons in axis y. Results One horizontal and one vertical defragging had the start Met at the center. Two, both horizontal and vertical pairings produced two pairs of 2×8×4 genetic code chromosomes naturally arranged (M and I), rearranged by semi-introversion of central purines or pyrimidines (M' and I') and by clustering hydrophobic amino acids; their quasi-identity was disrupted by amino acids with odd codons (Met and Tyr pairing to Ile and TGA Stop); in all instances, the 64-grid 90° rotational ability was restored. Conclusions We defragged three I Ching representations of the genetic code while emphasizing Nirenberg's historical finding. The synthetic genetic code chromosomes obtained reflect the protective strategy of enzymes with a similar function, having both humans and mammals a biased G-C dominance of three H-bonds in the third nucleotide of their most used codons per amino acid, as seen in one chromosome of the i, M and M' genetic codes, while a two H-bond A-T dominance was found in their complementary chromosome, as seen

  20. Defragged Binary I Ching Genetic Code Chromosomes Compared to Nirenberg's and Transformed into Rotating 2D Circles and Squares and into a 3D 100% Symmetrical Tetrahedron Coupled to a Functional One to Discern Start From Non-Start Methionines through a Stella Octangula.

    PubMed

    Castro-Chavez, Fernando

    2012-01-01

    BACKGROUND: Three binary representations of the genetic code according to the ancient I Ching of Fu-Xi will be presented, depending on their defragging capabilities by pairing based on three biochemical properties of the nucleic acids: H-bonds, Purine/Pyrimidine rings, and the Keto-enol/Amino-imino tautomerism, yielding the last pair a 32/32 single-strand self-annealed genetic code and I Ching tables. METHODS: Our working tool is the ancient binary I Ching's resulting genetic code chromosomes defragged by vertical and by horizontal pairing, reverse engineered into non-binaries of 2D rotating 4×4×4 circles and 8×8 squares and into one 3D 100% symmetrical 16×4 tetrahedron coupled to a functional tetrahedron with apical signaling and central hydrophobicity (codon formula: 4[1(1)+1(3)+1(4)+4(2)]; 5:5, 6:6 in man) forming a stella octangula, and compared to Nirenberg's 16×4 codon table (1965) pairing the first two nucleotides of the 64 codons in axis y. RESULTS: One horizontal and one vertical defragging had the start Met at the center. Two, both horizontal and vertical pairings produced two pairs of 2×8×4 genetic code chromosomes naturally arranged (M and I), rearranged by semi-introversion of central purines or pyrimidines (M' and I') and by clustering hydrophobic amino acids; their quasi-identity was disrupted by amino acids with odd codons (Met and Tyr pairing to Ile and TGA Stop); in all instances, the 64-grid 90° rotational ability was restored. CONCLUSIONS: We defragged three I Ching representations of the genetic code while emphasizing Nirenberg's historical finding. The synthetic genetic code chromosomes obtained reflect the protective strategy of enzymes with a similar function, having both humans and mammals a biased G-C dominance of three H-bonds in the third nucleotide of their most used codons per amino acid, as seen in one chromosome of the i, M and M' genetic codes, while a two H-bond A-T dominance was found in their complementary chromosome, as

  1. Nanostructured conducting polymer based reagentless capacitive immunosensor.

    PubMed

    Bandodkar, Amay Jairaj; Dhand, Chetna; Arya, Sunil K; Pandey, M K; Malhotra, Bansi D

    2010-02-01

    Nanostructured polyaniline (PANI) film electrophoretically fabricated onto indium-tin-oxide (ITO) coated glass plate has been utilized for development of an immunosensor based on capacitance change of a parallel plate capacitor (PPC) by covalently immobilizing anti-human IgG (Anti-HIgG) using N-ethyl-N'-(3-dimethylaminopropyl) carbodiimide and N-hydroxysuccinimide chemistry. These fabricated PANI/ITO and Anti-HIgG/PANI/ITO plates have been characterized using scanning electron microscopy, cyclic voltammetry, differential pulse voltammetry and Fourier transform infra-red studies. The capacitance measurements indicate that dielectric medium of this biologically modified PPC (Anti-HIgG/PANI/ITO) is sensitive to HIgG in 5 - 5 x 10(5) ng mL(-1) range and has lower detection limit of 1.87 ng mL(-1). The observed results reveal that this Anti-HIgG modified PPC can be used as a robust, easy-to-use, reagentless, sensitive and selective immunosensor for estimation of human IgG.

  2. Active shunt capacitance cancelling oscillator circuit

    DOEpatents

    Wessendorf, Kurt O.

    2003-09-23

    An oscillator circuit is disclosed which can be used to produce oscillation using a piezoelectric crystal, with a frequency of oscillation being largely independent of any shunt capacitance associated with the crystal (i.e. due to electrodes on the surfaces of the crystal and due to packaging and wiring for the crystal). The oscillator circuit is based on a tuned gain stage which operates the crystal at a frequency, f, near a series resonance frequency, f.sub.S. The oscillator circuit further includes a compensation circuit that supplies all the ac current flow through the shunt resistance associated with the crystal so that this ac current need not be supplied by the tuned gain stage. The compensation circuit uses a current mirror to provide the ac current flow based on the current flow through a reference capacitor that is equivalent to the shunt capacitance associated with the crystal. The oscillator circuit has applications for driving piezoelectric crystals for sensing of viscous, fluid or solid media by detecting a change in the frequency of oscillation of the crystal and a resonator loss which occur from contact of an exposed surface of the crystal by the viscous, fluid or solid media.

  3. Proportional microvolume capacitive liquid level sensor array.

    PubMed

    Seliskar, D; Waterbury, R; Kearney, R

    2005-01-01

    A sensor array has been developed for use with laboratory automation to permit closed-loop control of liquid levels in a multiwell microplate geometry. We extended a simple electrical model for non-contact capacitance-based fluid sensors to describe a fluid-level dependency. The new model shows that a charge-transfer based capacitance transducer, employing a liquid-specific calibration, can be used to obtain an output signal that varies linearly with the liquid level. The calibration also compensates for liquid-to-liquid conductivity and permittivity differences. A prototype 3×3 sensor array was built and tested using NaCl and ethanol solutions to simulate the range of conductivity and permittivity typical in biological and chemical research. Calibrated output signals were linear with liquid volume for all tested solutions (R2>0.92). Measurement error averaged 1.3 % (2.0 μl) with a standard deviation of 6.0% (9.0 μl). These results demonstrate the feasibility of developing a microvolume sensor array in essentially any M×N microplate geometry. PMID:17281955

  4. Capacitive micromachined ultrasonic transducers: fabrication technology.

    PubMed

    Ergun, Arif Sanli; Huang, Yongli; Zhuang, Xuefeng; Oralkan, Omer; Yaralioglu, Goksen G; Khuri-Yakub, Butrus T

    2005-12-01

    Capacitive micromachined ultrasonic transducer (cMUT) technology is a prime candidate for next generation imaging systems. Medical and underwater imaging and the nondestructive evaluation (NDE) societies have expressed growing interest in cMUTs over the years. Capacitive micromachined ultrasonic transducer technology is expected to make a strong impact on imaging technologies, especially volumetric imaging, and to appear in commercial products in the near future. This paper focuses on fabrication technologies for cMUTs and reviews and compares variations in the production processes. We have developed two main approaches to the fabrication of cMUTs: the sacrificial release process and the recently introduced wafer-bonding method. This paper gives a thorough review of the sacrificial release processes, and it describes the new wafer-bonding method in detail. Process variations are compared qualitatively and quantitatively whenever possible. Through these comparisons, it was concluded that wafer-bonded cMUT technology was superior in terms of process control, yield, and uniformity. Because the number of steps and consequent process time were reduced (from six-mask process to four-mask process), turn-around time was improved significantly. PMID:16463490

  5. Cosmic ray acceleration by binary neutron stars

    NASA Astrophysics Data System (ADS)

    Kundt, W.

    Young binary neutron stars, the elder brothers of pulsars, are proposed as the boosters of the ionic component of cosmic rays. Their rotational energy can be converted into beams of cosmic rays if there is enough coupling between the corotating magnetosphere and the impinging plasma, in a manner similar to the sparking of a grindstone. Power-law spectra in energy are obtained from a power-law dependence of the accelerating fields. The upper cutoff energy should not greatly exceed 10 to the 20th eV. The observed ionic cosmic-ray spectrum would result from a superposition of the injection by no more than about one million young binary neutron stars.

  6. Adaptive Mesh Refinement Simulations of Relativistic Binaries

    NASA Astrophysics Data System (ADS)

    Motl, Patrick M.; Anderson, M.; Lehner, L.; Olabarrieta, I.; Tohline, J. E.; Liebling, S. L.; Rahman, T.; Hirschman, E.; Neilsen, D.

    2006-09-01

    We present recent results from our efforts to evolve relativistic binaries composed of compact objects. We simultaneously solve the general relativistic hydrodynamics equations to evolve the material components of the binary and Einstein's equations to evolve the space-time. These two codes are coupled through an adaptive mesh refinement driver (had). One of the ultimate goals of this project is to address the merger of a neutron star and black hole and assess the possible observational signature of such systems as gamma ray bursts. This work has been supported in part by NSF grants AST 04-07070 and PHY 03-26311 and in part through NASA's ATP program grant NAG5-13430. The computations were performed primarily at NCSA through grant MCA98N043 and at LSU's Center for Computation & Technology.

  7. Gravitational waves from spinning eccentric binaries

    NASA Astrophysics Data System (ADS)

    Csizmadia, Péter; Debreczeni, Gergely; Rácz, István; Vasúth, Mátyás

    2012-12-01

    This paper is to introduce a new software called CBwaves which provides a fast and accurate computational tool to determine the gravitational waveforms yielded by generic spinning binaries of neutron stars and/or black holes on eccentric orbits. This is done within the post-Newtonian (PN) framework by integrating the equations of motion and the spin precession equations, while the radiation field is determined by a simultaneous evaluation of the analytic waveforms. In applying CBwaves various physically interesting scenarios have been investigated. In particular, we have studied the appropriateness of the adiabatic approximation, and justified that the energy balance relation is indeed insensitive to the specific form of the applied radiation reaction term. By studying eccentric binary systems, it is demonstrated that circular template banks are very ineffective in identifying binaries even if they possess tiny residual orbital eccentricity, thus confirming a similar result obtained by Brown and Zimmerman (2010 Phys. Rev. D 81 024007). In addition, by investigating the validity of the energy balance relation we show that, contrary to the general expectations, the PN approximation should not be applied once the PN parameter gets beyond the critical value ˜0.08 - 0.1. Finally, by studying the early phase of the gravitational waves emitted by strongly eccentric binary systems—which could be formed e.g. in various many-body interactions in the galactic halo—we have found that they possess very specific characteristics which may be used to identify these type of binary systems. This paper is dedicated to the memory of our colleague and friend Péter Csizmadia a young physicist, computer expert and one of the best Hungarian mountaineers who disappeared in China’s Sichuan near the Ren Zhong Feng peak of the Himalayas on 23 Oct. 2009. We started to develop CBwaves jointly with Péter a couple of months before he left for China.

  8. Enhancing capacitance behaviour of CoOOH nanostructures using transition metal dopants by ambient oxidation

    PubMed Central

    Chen, Yanhui; Zhou, Junfeng; Maguire, Pierce; O’Connell, Robert; Schmitt, Wolfgang; Li, Yonghe; Yan, Zhengguang; Zhang, Yuefei; Zhang, Hongzhou

    2016-01-01

    Cobalt hydrate and doped binary Co0.9M0.1OOH (M = Ni, Mn, Fe) nanorings of 100–300 nm were fabricated in solution through a facile ambient oxidation method. A transformation from Co0.9Ni0.1(OH)2 nanodiscs to hollow Co0.9Ni0.1OOH nanorings was observed with prolonged reaction time. Core-shell nanodiscs have elemental segregation with a Co(OH)2 core and Ni(OH)2 shell. Co0.9Ni0.1OOH nanorings displayed a higher electrochemical capacitance than Mn and Fe doped nanorings materials or materials with disc-like geometries. PMID:26853105

  9. BROWN DWARF BINARIES FROM DISINTEGRATING TRIPLE SYSTEMS

    SciTech Connect

    Reipurth, Bo; Mikkola, Seppo E-mail: Seppo.Mikkola@utu.fi

    2015-04-15

    Binaries in which both components are brown dwarfs (BDs) are being discovered at an increasing rate, and their properties may hold clues to their origin. We have carried out 200,000 N-body simulations of three identical stellar embryos with masses drawn from a Chabrier IMF and embedded in a molecular core. The bodies are initially non-hierarchical and undergo chaotic motions within the cloud core, while accreting using Bondi–Hoyle accretion. The coupling of dynamics and accretion often leads to one or two dominant bodies controlling the center of the cloud core, while banishing the other(s) to the lower-density outskirts, leading to stunted growth. Eventually each system transforms either to a bound hierarchical configuration or breaks apart into separate single and binary components. The orbital motion is followed for 100 Myr. In order to illustrate 200,000 end-states of such dynamical evolution with accretion, we introduce the “triple diagnostic diagram,” which plots two dimensionless numbers against each other, representing the binary mass ratio and the mass ratio of the third body to the total system mass. Numerous freefloating BD binaries are formed in these simulations, and statistical properties are derived. The separation distribution function is in good correspondence with observations, showing a steep rise at close separations, peaking around 13 AU and declining more gently, reaching zero at separations greater than 200 AU. Unresolved BD triple systems may appear as wider BD binaries. Mass ratios are strongly peaked toward unity, as observed, but this is partially due to the initial assumptions. Eccentricities gradually increase toward higher values, due to the lack of viscous interactions in the simulations, which would both shrink the orbits and decrease their eccentricities. Most newborn triple systems are unstable and while there are 9209 ejected BD binaries at 1 Myr, corresponding to about 4% of the 200,000 simulations, this number has grown to

  10. Brown Dwarf Binaries from Disintegrating Triple Systems

    NASA Astrophysics Data System (ADS)

    Reipurth, Bo; Mikkola, Seppo

    2015-04-01

    Binaries in which both components are brown dwarfs (BDs) are being discovered at an increasing rate, and their properties may hold clues to their origin. We have carried out 200,000 N-body simulations of three identical stellar embryos with masses drawn from a Chabrier IMF and embedded in a molecular core. The bodies are initially non-hierarchical and undergo chaotic motions within the cloud core, while accreting using Bondi-Hoyle accretion. The coupling of dynamics and accretion often leads to one or two dominant bodies controlling the center of the cloud core, while banishing the other(s) to the lower-density outskirts, leading to stunted growth. Eventually each system transforms either to a bound hierarchical configuration or breaks apart into separate single and binary components. The orbital motion is followed for 100 Myr. In order to illustrate 200,000 end-states of such dynamical evolution with accretion, we introduce the “triple diagnostic diagram,” which plots two dimensionless numbers against each other, representing the binary mass ratio and the mass ratio of the third body to the total system mass. Numerous freefloating BD binaries are formed in these simulations, and statistical properties are derived. The separation distribution function is in good correspondence with observations, showing a steep rise at close separations, peaking around 13 AU and declining more gently, reaching zero at separations greater than 200 AU. Unresolved BD triple systems may appear as wider BD binaries. Mass ratios are strongly peaked toward unity, as observed, but this is partially due to the initial assumptions. Eccentricities gradually increase toward higher values, due to the lack of viscous interactions in the simulations, which would both shrink the orbits and decrease their eccentricities. Most newborn triple systems are unstable and while there are 9209 ejected BD binaries at 1 Myr, corresponding to about 4% of the 200,000 simulations, this number has grown to

  11. Gravitational wave astrophysics with compact binary systems

    NASA Astrophysics Data System (ADS)

    Addison, Eric

    2014-10-01

    Gravitational waves are ripples in the fabric of spacetime that convey information about changing gravitational fields. Large-scale detection projects are currently in operation, and more advanced detectors are being designed and built. Though we have yet to make a direct detection of a gravitational wave signal, upgrades to current detectors are expected to bring the first detections within the next year or two. Gravitational waves will bring us information about astrophysical phenomena that is complementary to the information gained from photon-based observations (e.g., telescopes and radio receivers). One of the primary sources of gravitational waves are binary systems: two massive objects that orbit around each other due to their mutual gravitational attraction. These systems can have very predictable gravitational wave signatures due to their repetitive motions, making them ideal gravitational wave sources. In this dissertation, I present two research projects pertaining to gravitational wave astrophysics and compact binary systems. In the first, I explore interactions between compact binary systems near the center of our galaxy with the supermassive black hole that resides there. I am interested in the final state of the binary as a result of the interaction, ranging from small perturbations to the orbit up to total disruption. In the case of disruption, I characterize the new orbits formed between the binary components and the central black hole, known as extreme mass ratio inspirals. For binaries that survive the encounter, I examine the changes they experience, and find on average, they will merge together as a result of gravitational wave emission faster than before the encounter. In the second project, I propose a new method of measuring the radius of the swirling disc of gas and dust that encircles some stars in compact binary systems, known as the accretion disc. This method relies on the use of coupled electromagnetic and gravitational wave

  12. Massive Black Hole Binary Evolution

    NASA Astrophysics Data System (ADS)

    Merritt, David; Milosavljević, Milos

    2005-11-01

    Coalescence of binary supermassive black holes (SBHs) would constitute the strongest sources of gravitational waves to be observed by LISA. While the formation of binary SBHs during galaxy mergers is almost inevitable, coalescence requires that the separation between binary components first drop by a few orders of magnitude, due presumably to interaction of the binary with stars and gas in a galactic nucleus. This article reviews the observational evidence for binary SBHs and discusses how they would evolve. No completely convincing case of a bound, binary SBH has yet been found, although a handful of systems (e.g. interacting galaxies; remnants of galaxy mergers) are now believed to contain two SBHs at projected separations of <~ 1kpc. N-body studies of binary evolution in gas-free galaxies have reached large enough particle numbers to reproduce the slow, "diffusive" refilling of the binary's loss cone that is believed to characterize binary evolution in real galactic nuclei. While some of the results of these simulations - e.g. the binary hardening rate and eccentricity evolution - are strongly N-dependent, others - e.g. the "damage" inflicted by the binary on the nucleus - are not. Luminous early-type galaxies often exhibit depleted cores with masses of ~ 1-2 times the mass of their nuclear SBHs, consistent with the predictions of the binary model. Studies of the interaction of massive binaries with gas are still in their infancy, although much progress is expected in the near future. Binary coalescence has a large influence on the spins of SBHs, even for mass ratios as extreme as 10:1, and evidence of spin-flips may have been observed.

  13. Binary Love relations

    NASA Astrophysics Data System (ADS)

    Yagi, Kent; Yunes, Nicolás

    2016-07-01

    When in a tight binary, the mutual tidal deformations of neutron stars get imprinted onto observables, encoding information about their internal structure at supranuclear densities and gravity in the extreme-gravity regime. Gravitational wave (GW) observations of their late binary inspiral may serve as a tool to extract the individual tidal deformabilities, but this is made difficult by degeneracies between them in the GW model. We here resolve this problem by discovering approximately equation-of-state (EoS)-insensitive relations between dimensionless combinations of the individual tidal deformabilities. We show that these relations break degeneracies in the GW model, allowing for the accurate extraction of both deformabilities. Such measurements can be used to better differentiate between EoS models, and improve tests of general relativity and cosmology.

  14. Capacitive bioanodes enable renewable energy storage in microbial fuel cells.

    PubMed

    Deeke, Alexandra; Sleutels, Tom H J A; Hamelers, Hubertus V M; Buisman, Cees J N

    2012-03-20

    We developed an integrated system for storage of renewable electricity in a microbial fuel cell (MFC). The system contained a capacitive electrode that was inserted into the anodic compartment of an MFC to form a capacitive bioanode. This capacitive bioanode was compared with a noncapacitive bioanode on the basis of performance and storage capacity. The performance and storage capacity were investigated during polarization curves and charge-discharge experiments. During polarization curves the capacitive electrode reached a maximum current density of 1.02 ± 0.04 A/m(2), whereas the noncapacitive electrode reached a current density output of only 0.79 ± 0.03 A/m(2). During the charge-discharge experiment with 5 min of charging and 20 min of discharging, the capacitive electrode was able to store a total of 22,831 C/m(2), whereas the noncapacitive electrode was only able to store 12,195 C/m(2). Regarding the charge recovery of each electrode, the capacitive electrode was able to recover 52.9% more charge during each charge-discharge experiment compared with the noncapacitive electrode. The capacitive electrode outperformed the noncapacitive electrode throughout each charge-discharge experiment. With a capacitive electrode it is possible to use the MFC simultaneously for production and storage of renewable electricity.

  15. Large Capacitance Measurement by Multiple Uses of MBL Charge Sensor

    ERIC Educational Resources Information Center

    Lee, Jung Sook; Chae, Min; Kim, Jung Bog

    2010-01-01

    A recent article by Morse described interesting electrostatics experiments using an MBL charge sensor. In this application, the charge sensor has a large capacitance compared to the charged test object, so nearly all charges can be transferred to the sensor capacitor from the capacitor to be measured. However, the typical capacitance of commercial…

  16. Parametric binary dissection

    NASA Technical Reports Server (NTRS)

    Bokhari, Shahid H.; Crockett, Thomas W.; Nicol, David M.

    1993-01-01

    Binary dissection is widely used to partition non-uniform domains over parallel computers. This algorithm does not consider the perimeter, surface area, or aspect ratio of the regions being generated and can yield decompositions that have poor communication to computation ratio. Parametric Binary Dissection (PBD) is a new algorithm in which each cut is chosen to minimize load + lambda x(shape). In a 2 (or 3) dimensional problem, load is the amount of computation to be performed in a subregion and shape could refer to the perimeter (respectively surface) of that subregion. Shape is a measure of communication overhead and the parameter permits us to trade off load imbalance against communication overhead. When A is zero, the algorithm reduces to plain binary dissection. This algorithm can be used to partition graphs embedded in 2 or 3-d. Load is the number of nodes in a subregion, shape the number of edges that leave that subregion, and lambda the ratio of time to communicate over an edge to the time to compute at a node. An algorithm is presented that finds the depth d parametric dissection of an embedded graph with n vertices and e edges in O(max(n log n, de)) time, which is an improvement over the O(dn log n) time of plain binary dissection. Parallel versions of this algorithm are also presented; the best of these requires O((n/p) log(sup 3)p) time on a p processor hypercube, assuming graphs of bounded degree. How PBD is applied to 3-d unstructured meshes and yields partitions that are better than those obtained by plain dissection is described. Its application to the color image quantization problem is also discussed, in which samples in a high-resolution color space are mapped onto a lower resolution space in a way that minimizes the color error.

  17. Binary Optics Toolkit

    1996-04-02

    This software is a set of tools for the design and analysis of binary optics. It consists of a series of stand-alone programs written in C and some scripts written in an application-specific language interpreted by a CAD program called DW2000. This software can be used to optimize the design and placement of a complex lens array from input to output and produce contours, mask designs, and data exported for diffractive optic analysis.

  18. Nonlinear electron resonance heating in dual frequency capacitive discharges

    NASA Astrophysics Data System (ADS)

    Ziegler, D.; Mussenbrock, T.; Brinkmann, R. P.

    2006-10-01

    Capacitively coupled plasmas (CCP's) play a major role in material processing. The drawback of conventional single frequency CCP's is that the ion bombardment energy and the ion flux to the substrate itself cannot be controlled independently. The problem can be remedied by the use of dual frequency CCP's. In such sources, the ratio of the applied frequencies is obviously an important control parameter. Rauf^1 found that at large ratios (e.g., 100,kHz/13.56,MHz) the spectrum of the discharge current was just the superposition of two single-frequency spectra. For more comparable frequencies (e.g.,6.78,MHz/13.56,MHz), however, quite surprising nonlinear effects were observed. It is exactly this nonlinear behavior and its influence on the total energy budget that is discussed in this contribution - we present and analyze a nonlinear global model for a dual frequency CCP. Based on an exact analytical solution of the underlying equations we discuss the behavior of the model for various voltage ratios, frequency ratios, and gas pressures. We investigate in particular the heating at the plasma series resonance, either by direct excitation or via the nonlinear electron resonance heating mechanism^2. ^1 S. Rauf and M.J. Kushner, IEEE Trans Plasma Sci. 27, 1329 (1999)^2 T. Mussenbrock and R.P. Brinkmann, Appl. Phys. Lett. 88, 151503 (2006)

  19. Capacitive charge generation apparatus and method for testing circuits

    DOEpatents

    Cole, Jr., Edward I.; Peterson, Kenneth A.; Barton, Daniel L.

    1998-01-01

    An electron beam apparatus and method for testing a circuit. The electron beam apparatus comprises an electron beam incident on an outer surface of an insulating layer overlying one or more electrical conductors of the circuit for generating a time varying or alternating current electrical potential on the surface; and a measurement unit connected to the circuit for measuring an electrical signal capacitively coupled to the electrical conductors to identify and map a conduction state of each of the electrical conductors, with or without an electrical bias signal being applied to the circuit. The electron beam apparatus can further include a secondary electron detector for forming a secondary electron image for registration with a map of the conduction state of the electrical conductors. The apparatus and method are useful for failure analysis or qualification testing to determine the presence of any open-circuits or short-circuits, and to verify the continuity or integrity of electrical conductors buried below an insulating layer thickness of 1-100 .mu.m or more without damaging or breaking down the insulating layer. The types of electrical circuits that can be tested include integrated circuits, multi-chip modules, printed circuit boards and flexible printed circuits.

  20. Capacitive charge generation apparatus and method for testing circuits

    DOEpatents

    Cole, E.I. Jr.; Peterson, K.A.; Barton, D.L.

    1998-07-14

    An electron beam apparatus and method for testing a circuit are disclosed. The electron beam apparatus comprises an electron beam incident on an outer surface of an insulating layer overlying one or more electrical conductors of the circuit for generating a time varying or alternating current electrical potential on the surface; and a measurement unit connected to the circuit for measuring an electrical signal capacitively coupled to the electrical conductors to identify and map a conduction state of each of the electrical conductors, with or without an electrical bias signal being applied to the circuit. The electron beam apparatus can further include a secondary electron detector for forming a secondary electron image for registration with a map of the conduction state of the electrical conductors. The apparatus and method are useful for failure analysis or qualification testing to determine the presence of any open-circuits or short-circuits, and to verify the continuity or integrity of electrical conductors buried below an insulating layer thickness of 1-100 {micro}m or more without damaging or breaking down the insulating layer. The types of electrical circuits that can be tested include integrated circuits, multi-chip modules, printed circuit boards and flexible printed circuits. 7 figs.

  1. Integrating reverse electrodialysis with constant current operating capacitive deionization.

    PubMed

    Jande, Y A C; Kim, W S

    2014-12-15

    The presence of a salinity gradient between saline water streams may result in the production of electricity via either reverse electrodialysis (RED) or forward osmosis. While the former system generates electricity because of the ionic current, the latter process produces electricity due to the osmotic pressure. In this study, RED is coupled with capacitive deionization (CDI) so that highly pure water, fresh water and electricity could be generated simultaneously. A CDI cell is operated at constant current, and it generated ultrapure water and two streams (a lower salinity stream of approximately 17.4 mol NaCl per m(3) and a high salinity stream of approximately 512.8 mol NaCl per m(3)) to be fed to the RED stack from a 15,000 ppm CDI feed concentration. The performed simulation reveals that, the total power generated from the RED using infinitely divided electrodes is 0.57 W/m(2) electrode area. The use of RED in a CDI plant introduces a new approach to minimize CDI brine concentration, which would otherwise have a negative impact on the environment if it were disposed directly without prior treatment. PMID:25150096

  2. Transport of sputtered particles in capacitive sputter sources

    NASA Astrophysics Data System (ADS)

    Trieschmann, Jan; Mussenbrock, Thomas

    2015-07-01

    The transport of sputtered aluminum inside a multi frequency capacitively coupled plasma chamber is simulated by means of a kinetic test multi-particle approach. A novel consistent set of scattering parameters obtained for a modified variable hard sphere collision model is presented for both argon and aluminum. An angular dependent Thompson energy distribution is fitted to results from Monte Carlo simulations and used for the kinetic simulation of the transport of sputtered aluminum. For the proposed configuration, the transport of sputtered particles is characterized under typical process conditions at a gas pressure of p = 0.5 Pa. It is found that—due to the peculiar geometric conditions—the transport can be understood in a one dimensional picture, governed by the interaction of the imposed and backscattered particle fluxes. It is shown that the precise geometric features play an important role only in proximity to the electrode edges, where the effect of backscattering from the outside chamber volume becomes the governing mechanism.

  3. Separated Fringe Packet Binaries

    NASA Astrophysics Data System (ADS)

    Bagnuolo, W. G.; Taylor, S. F.; McAlister, H. A.; ten Brummelaar, T.; Sturmann, L.; Sturmann, J.; Turner, N. H.; Berger, D.; Ridgway, S. T.; CenterHigh Angular Resolution Astronomy (CHARA)

    2004-12-01

    Individually resolved packets are produced by scans from the CHARA Interferometer Array for binary stars with separations from 10 to 100 milli-arcsec (mas) in the K' band. We have used this data for astrometry of the binary with the goal of improving the visual orbits for these systems. About 12 data sets of 400 scans each can be collected for a star within an hour. The intrinsic accuracy with simple linear/quadratic fits to the time-separation curve yields accuracies of 0.15 mas. But, for systems with separations less than 80 mas, the measured separation is modulated periodically by the secondary star's packet riding over the sidelobes of the primary which provides a phase reference. This "sidelobe verniering" can improve the precision to better than 50 micro-arcsec. These techniques, represents 1-2 orders of magnitude improvement in astrometic accuracy over speckle interferometry techniques. Visual orbits can then be refined via a maximum liklihood technique, which leads to revisions in the stellar masses. We present the results for several binaries that have been observed at the CHARA Array, starting in 2001.

  4. Evolutionary models of binaries

    NASA Astrophysics Data System (ADS)

    van Rensbergen, Walter; Mennekens, Nicki; de Greve, Jean-Pierre; Jansen, Kim; de Loore, Bert

    2011-07-01

    We have put on CDS a catalog containing 561 evolutionary models of binaries: J/A+A/487/1129 (Van Rensbergen+, 2008). The catalog covers a grid of binaries with a B-type primary at birth, different values for the initial mass ratio and a wide range of initial orbital periods. The evolution was calculated with the Brussels code in which we introduced the spinning up and the creation of a hot spot on the gainer or its accretion disk, caused by impacting mass coming from the donor. When the kinetic energy of fast rotation added to the radiative energy of the hot spot exceeds the binding energy, a fraction of the transferred matter leaves the system: the evolution is liberal during a short lasting era of rapid mass transfer. The spin-up of the gainer was modulated using both strong and weak tides. The catalog shows the results for both types. For comparison, we included the evolutionary tracks calculated with the conservative assumption. Binaries with an initial primary below 6 Msolar show hardly any mass loss from the system and thus evolve conservatively. Above this limit differences between liberal and conservative evolution grow with increasing initial mass of the primary star.

  5. On the Eccentricity Excitation in Post-main-sequence Binaries

    NASA Astrophysics Data System (ADS)

    Rafikov, Roman R.

    2016-10-01

    Several classes of stellar binaries with post-main-sequence (post-MS) components—millisecond pulsars with the white dwarf companions (MSP+WD) and periods of {P}b∼ 30 days, binaries hosting post-asymptotic giant branch stars, or barium stars with {P}b ∼ several years—feature high eccentricities (up to 0.4) despite the expectation of their efficient tidal circularization during their post-MS evolution. It was suggested that the eccentricities of these binaries can be naturally excited by their tidal coupling to the circumbinary disk, formed by the material ejected from the binary. Here we critically reassess this idea using simple arguments rooted in the global angular momentum conservation of the disk+binary system. Compared to previous studies, we (1) fully account for the viscous spreading of the circumbinary disk, (2) consider the possibility of reaccretion from the disk onto the binary (in agreement with simulations and empirical evidence), and (3) allow for the reduced viscosity after the disk expands, cools, and forms dust. These ingredients conspire to significantly lower the efficiency of eccentricity excitation by the disk tides. We find that explaining eccentricities of the post-MS binaries is difficult and requires massive (≳ {10}-2 {M}ȯ ), long-lived (≳ {10}5 years) circumbinary disks that do not reaccrete. While disk tides may account for the eccentricities of the MSP+WD binaries, we show reaccretion to also be detrimental for these systems. Reduced efficiency of the disk-driven excitation motivates the study of alternative mechanisms for producing the peculiar eccentricities of the post-MS binaries.

  6. Electrostatic capacitance and Faraday cage behavior of carbon nanotube forests

    SciTech Connect

    Ya'akobovitz, A.; Bedewy, M.; Hart, A. J.

    2015-02-02

    Understanding of the electrostatic properties of carbon nanotube (CNT) forests is essential to enable their integration in microelectronic and micromechanical devices. In this study, we sought to understand how the hierarchical geometry and morphology of CNT forests determines their capacitance. First, we find that at small gaps, solid micropillars have greater capacitance, yet at larger gaps the capacitance of the CNT forests is greater. The surface area of the CNT forest accessible to the electrostatic field was extracted by analysis of the measured capacitance, and, by relating the capacitance to the average density of CNTs in the forest, we find that the penetration depth of the electrostatic field is on the order of several microns. Therefore, CNT forests can behave as a miniature Faraday cage. The unique electrostatic properties of CNT forests could therefore enable their use as long-range proximity sensors and as shielding elements for miniature electronic devices.

  7. Electrostatic capacitance and Faraday cage behavior of carbon nanotube forests

    NASA Astrophysics Data System (ADS)

    Ya'akobovitz, A.; Bedewy, M.; Hart, A. J.

    2015-02-01

    Understanding of the electrostatic properties of carbon nanotube (CNT) forests is essential to enable their integration in microelectronic and micromechanical devices. In this study, we sought to understand how the hierarchical geometry and morphology of CNT forests determines their capacitance. First, we find that at small gaps, solid micropillars have greater capacitance, yet at larger gaps the capacitance of the CNT forests is greater. The surface area of the CNT forest accessible to the electrostatic field was extracted by analysis of the measured capacitance, and, by relating the capacitance to the average density of CNTs in the forest, we find that the penetration depth of the electrostatic field is on the order of several microns. Therefore, CNT forests can behave as a miniature Faraday cage. The unique electrostatic properties of CNT forests could therefore enable their use as long-range proximity sensors and as shielding elements for miniature electronic devices.

  8. Phase discriminating capacitive array sensor system

    NASA Technical Reports Server (NTRS)

    Vranish, John M. (Inventor); Rahim, Wadi (Inventor)

    1993-01-01

    A phase discriminating capacitive sensor array system which provides multiple sensor elements which are maintained at a phase and amplitude based on a frequency reference provided by a single frequency stabilized oscillator. Sensor signals provided by the multiple sensor elements are controlled by multiple phase control units, which correspond to the multiple sensor elements, to adjust the sensor signals from the multiple sensor elements based on the frequency reference. The adjustment made to the sensor signals is indicated by output signals which indicate the proximity of the object. The output signals may also indicate the closing speed of the object based on the rate of change of the adjustment made, and the edges of the object based on a sudden decrease in the adjustment made.

  9. In-line rotating capacitive torque sensor

    DOEpatents

    Kronberg, James W.

    1991-01-01

    A method and apparatus for measuring torques developed along a rotating mechanical assembly comprising a rotating inner portion and a stationary outer portion. The rotating portion has an electrically-conductive flexing section fitted between two coaxial shafts in a configuration which varies radially in accordance with applied torque. The stationary portion comprises a plurality of conductive plates forming a surface concentric with and having a diameter slightly larger than the diameter of the rotating portion. The capacitance between the outer, nonrotating and inner, rotating portion varies with changes in the radial configuration of the rotating portion. Signal output varies approximately linearly with torque for small torques, nonlinearly for larger torques. The sensor is preferably surrounded by a conductive shell to minimize electrical interference from external sources.

  10. A qualitative approach to teaching capacitive circuits

    NASA Astrophysics Data System (ADS)

    Smith, David P.; Kampen, Paul van

    2013-05-01

    We have investigated students' qualitative understanding of dc circuits containing resistors and a capacitor. We found that a year after traditional lecture instruction as part of an introductory physics course, most students were unable to predict the behavior of a series circuit consisting of a battery, a bulb, and a capacitor. Among the difficulties identified we found that almost half of the students implicitly abandoned the idea that a complete circuit is necessary for a bulb to light when a capacitor is introduced into the circuit. We have developed curriculum that enables students to construct a phenomenological model in which they liken the behavior of a capacitor to that of a wire, a switch, and a battery; this allows them to qualitatively describe circuits with batteries, bulbs, and capacitors. We have also developed curriculum on the determination of RC times. Post-test results show a significant increase in understanding of capacitive circuits.

  11. Further capacitive imaging experiments using modified probes

    NASA Astrophysics Data System (ADS)

    Yin, Xiaokang; Li, Zhen; Yan, An; Li, Wei; Chen, Guoming; Hutchins, David A.

    2016-02-01

    In recent years, capacitive imaging (CI) is growing in popularity within the NDE communities, as it has the potential to test materials and structures for defects that are not easily tested by other techniques. In previous work, The CI technique has been successfully used on a various types of materials, including concrete, glass/carbon fibre composite, steel, etc. In such CI experiments, the probes are normally with symmetric or concentric electrodes etched onto PCBs. In addition to these conventional coplanar PCB probes, modified geometries can be made and they can lead to different applications. A brief overview of these modified probes, including high resolution surface imaging probe, combined CI/eddy current probe, and CI probe using an oscilloscope probe as the sensing electrode, is presented in this work. The potential applications brought by these probes are also discussed.

  12. Binary-Signal Recovery

    NASA Technical Reports Server (NTRS)

    Griebeler, Elmer L.

    2011-01-01

    Binary communication through long cables, opto-isolators, isolating transformers, or repeaters can become distorted in characteristic ways. The usual solution is to slow the communication rate, change to a different method, or improve the communication media. It would help if the characteristic distortions could be accommodated at the receiving end to ease the communication problem. The distortions come from loss of the high-frequency content, which adds slopes to the transitions from ones to zeroes and zeroes to ones. This weakens the definition of the ones and zeroes in the time domain. The other major distortion is the reduction of low frequency, which causes the voltage that defines the ones or zeroes to drift out of recognizable range. This development describes a method for recovering a binary data stream from a signal that has been subjected to a loss of both higher-frequency content and low-frequency content that is essential to define the difference between ones and zeroes. The method makes use of the frequency structure of the waveform created by the data stream, and then enhances the characteristics related to the data to reconstruct the binary switching pattern. A major issue is simplicity. The approach taken here is to take the first derivative of the signal and then feed it to a hysteresis switch. This is equivalent in practice to using a non-resonant band pass filter feeding a Schmitt trigger. Obviously, the derivative signal needs to be offset to halfway between the thresholds of the hysteresis switch, and amplified so that the derivatives reliably exceed the thresholds. A transition from a zero to a one is the most substantial, fastest plus movement of voltage, and therefore will create the largest plus first derivative pulse. Since the quiet state of the derivative is sitting between the hysteresis thresholds, the plus pulse exceeds the plus threshold, switching the hysteresis switch plus, which re-establishes the data zero to one transition

  13. Two-dimensional simulation of inductive-capacitive transition instability in an electronegative plasma

    NASA Astrophysics Data System (ADS)

    Kawamura, E.; Lieberman, M. A.; Lichtenberg, A. J.; Graves, D. B.

    2012-08-01

    Plasma instabilities are observed in low-pressure inductive discharges in the transition between low density capacitively driven and high density inductively driven discharges when attaching gases are used. A two-dimensional hybrid fluid-analytic simulation is used to determine the space- and time-varying densities of electrons, positive and negative ions, and neutral species, and electron and neutral gas temperatures. The simulation includes both the capacitive and inductive coupling of the source coils to the plasma and the neutral gas dissociation and heating. The plasma is described using the time-dependent fluid equations, along with an analytical sheath model. The simulation is applied to an experiment in Cl2, in which gaps in the electron and positive ion densities versus power curves were observed, with our numerical results indicating the existence of an inductive-capacitive transition instability, corresponding approximately to the observed gaps. The fluid calculation captures various features that are not included in previous global instability models. A method is developed to match the numerical results to the global model formalism, which predicts the existence of the unstable mode, as numerically found. The time and space variations can be used to improve the global model formalism.

  14. The hysteresis-free negative capacitance field effect transistors using non-linear poly capacitance

    NASA Astrophysics Data System (ADS)

    Fan, S.-T.; Yan, J.-Y.; Lai, D.-C.; Liu, C. W.

    2016-08-01

    A gate structure design for negative capacitance field effect transistors (NCFETs) is proposed. The hysteresis loop in current-voltage performances is eliminated by the nonlinear C-V dependence of polysilicon in the gate dielectrics. Design considerations and optimizations to achieve the low SS and hysteresis-free transfer were elaborated. The effects of gate-to-source/drain overlap, channel length scaling, interface trap states and temperature impact on SS are also investigated.

  15. Experimental Analysis of Bisbenzocyclobutene Bonded Capacitive Micromachined Ultrasonic Transducers.

    PubMed

    Manwar, Rayyan; Chowdhury, Sazzadur

    2016-01-01

    Experimental measurement results of a 1.75 mm × 1.75 mm footprint area Capacitive Micromachined Ultrasonic Transducer (CMUT) planar array fabricated using a bisbenzocyclobutene (BCB)-based adhesive wafer bonding technique has been presented. The array consists of 40 × 40 square diaphragm CMUT cells with a cavity thickness of 900 nm and supported by 10 µm wide dielectric spacers patterned on a thin layer of BCB. A 150 µm wide one µm thick gold strip has been used as the contact pad for gold wire bonding. The measured resonant frequency of 19.3 MHz using a Polytec™ laser Doppler vibrometer (Polytec™ MSA-500) is in excellent agreement with the 3-D FEA simulation result using IntelliSuite™. An Agilent ENA5061B vector network analyzer (VNA) has been used for impedance measurement and the resonance and anti-resonance values from the imaginary impedance curve were used to determine the electromechanical coupling co-efficient. The measured coupling coefficient of 0.294 at 20 V DC bias exhibits 40% higher transduction efficiency as compared to a measured value published elsewhere for a silicon nitride based CMUT. A white light interferometry method was used to measure the diaphragm deflection profiles at different DC bias. The diaphragm center velocity was measured for different sub-resonant frequencies using a Polytec™ laser Doppler vibrometer that confirms vibration of the diaphragm at different excitation frequencies and bias voltages. Transmit and receive operations of CMUT cells were characterized using a pitch-catch method and a -6 dB fractional bandwidth of 23% was extracted from the received signal in frequency domain. From the measurement, it appears that BCB-based CMUTs offer superior transduction efficiency as compared to silicon nitride or silicon dioxide insulator-based CMUTs, and provide a very uniform deflection profile thus making them a suitable candidate to fabricate highly energy efficient CMUTs. PMID:27347955

  16. Experimental Analysis of Bisbenzocyclobutene Bonded Capacitive Micromachined Ultrasonic Transducers.

    PubMed

    Manwar, Rayyan; Chowdhury, Sazzadur

    2016-06-24

    Experimental measurement results of a 1.75 mm × 1.75 mm footprint area Capacitive Micromachined Ultrasonic Transducer (CMUT) planar array fabricated using a bisbenzocyclobutene (BCB)-based adhesive wafer bonding technique has been presented. The array consists of 40 × 40 square diaphragm CMUT cells with a cavity thickness of 900 nm and supported by 10 µm wide dielectric spacers patterned on a thin layer of BCB. A 150 µm wide one µm thick gold strip has been used as the contact pad for gold wire bonding. The measured resonant frequency of 19.3 MHz using a Polytec™ laser Doppler vibrometer (Polytec™ MSA-500) is in excellent agreement with the 3-D FEA simulation result using IntelliSuite™. An Agilent ENA5061B vector network analyzer (VNA) has been used for impedance measurement and the resonance and anti-resonance values from the imaginary impedance curve were used to determine the electromechanical coupling co-efficient. The measured coupling coefficient of 0.294 at 20 V DC bias exhibits 40% higher transduction efficiency as compared to a measured value published elsewhere for a silicon nitride based CMUT. A white light interferometry method was used to measure the diaphragm deflection profiles at different DC bias. The diaphragm center velocity was measured for different sub-resonant frequencies using a Polytec™ laser Doppler vibrometer that confirms vibration of the diaphragm at different excitation frequencies and bias voltages. Transmit and receive operations of CMUT cells were characterized using a pitch-catch method and a -6 dB fractional bandwidth of 23% was extracted from the received signal in frequency domain. From the measurement, it appears that BCB-based CMUTs offer superior transduction efficiency as compared to silicon nitride or silicon dioxide insulator-based CMUTs, and provide a very uniform deflection profile thus making them a suitable candidate to fabricate highly energy efficient CMUTs.

  17. Experimental Analysis of Bisbenzocyclobutene Bonded Capacitive Micromachined Ultrasonic Transducers

    PubMed Central

    Manwar, Rayyan; Chowdhury, Sazzadur

    2016-01-01

    Experimental measurement results of a 1.75 mm × 1.75 mm footprint area Capacitive Micromachined Ultrasonic Transducer (CMUT) planar array fabricated using a bisbenzocyclobutene (BCB)-based adhesive wafer bonding technique has been presented. The array consists of 40 × 40 square diaphragm CMUT cells with a cavity thickness of 900 nm and supported by 10 µm wide dielectric spacers patterned on a thin layer of BCB. A 150 µm wide one µm thick gold strip has been used as the contact pad for gold wire bonding. The measured resonant frequency of 19.3 MHz using a Polytec™ laser Doppler vibrometer (Polytec™ MSA-500) is in excellent agreement with the 3-D FEA simulation result using IntelliSuite™. An Agilent ENA5061B vector network analyzer (VNA) has been used for impedance measurement and the resonance and anti-resonance values from the imaginary impedance curve were used to determine the electromechanical coupling co-efficient. The measured coupling coefficient of 0.294 at 20 V DC bias exhibits 40% higher transduction efficiency as compared to a measured value published elsewhere for a silicon nitride based CMUT. A white light interferometry method was used to measure the diaphragm deflection profiles at different DC bias. The diaphragm center velocity was measured for different sub-resonant frequencies using a Polytec™ laser Doppler vibrometer that confirms vibration of the diaphragm at different excitation frequencies and bias voltages. Transmit and receive operations of CMUT cells were characterized using a pitch-catch method and a −6 dB fractional bandwidth of 23% was extracted from the received signal in frequency domain. From the measurement, it appears that BCB-based CMUTs offer superior transduction efficiency as compared to silicon nitride or silicon dioxide insulator-based CMUTs, and provide a very uniform deflection profile thus making them a suitable candidate to fabricate highly energy efficient CMUTs. PMID:27347955

  18. The Electrochemical Flow Capacitor: Capacitive Energy Storage in Flowable Media

    NASA Astrophysics Data System (ADS)

    Dennison, Christopher R.

    Electrical energy storage (EES) has emerged as a necessary aspect of grid infrastructure to address the increasing problem of grid instability imposed by the large scale implementation of renewable energy sources (such as wind or solar) on the grid. Rapid energy recovery and storage is critically important to enable immediate and continuous utilization of these resources, and provides other benefits to grid operators and consumers as well. In past decades, there has been significant progress in the development of electrochemical EES technologies which has had an immense impact on the consumer and micro-electronics industries. However, these advances primarily address small-scale storage, and are often not practical at the grid-scale. A new energy storage concept called "the electrochemical flow capacitor (EFC)" has been developed at Drexel which has significant potential to be an attractive technology for grid-scale energy storage. This new concept exploits the characteristics of both supercapacitors and flow batteries, potentially enabling fast response rates with high power density, high efficiency, and long cycle lifetime, while decoupling energy storage from power output (i.e., scalable energy storage capacity). The unique aspect of this concept is the use of flowable carbon-electrolyte slurry ("flowable electrode") as the active material for capacitive energy storage. This dissertation work seeks to lay the scientific groundwork necessary to develop this new concept into a practical technology, and to test the overarching hypothesis that energy can be capacitively stored and recovered from a flowable media. In line with these goals, the objectives of this Ph.D. work are to: i) perform an exploratory investigation of the operating principles and demonstrate the technical viability of this new concept and ii) establish a scientific framework to assess the key linkages between slurry composition, flow cell design, operating conditions and system performance. To

  19. Automatic target detection using binary template matching

    NASA Astrophysics Data System (ADS)

    Jun, Dong-San; Sun, Sun-Gu; Park, HyunWook

    2005-03-01

    This paper presents a new automatic target detection (ATD) algorithm to detect targets such as battle tanks and armored personal carriers in ground-to-ground scenarios. Whereas most ATD algorithms were developed for forward-looking infrared (FLIR) images, we have developed an ATD algorithm for charge-coupled device (CCD) images, which have superior quality to FLIR images in daylight. The proposed algorithm uses fast binary template matching with an adaptive binarization, which is robust to various light conditions in CCD images and saves computation time. Experimental results show that the proposed method has good detection performance.

  20. Binary optics: Trends and limitations

    NASA Technical Reports Server (NTRS)

    Farn, Michael W.; Veldkamp, Wilfrid B.

    1993-01-01

    We describe the current state of binary optics, addressing both the technology and the industry (i.e., marketplace). With respect to the technology, the two dominant aspects are optical design methods and fabrication capabilities, with the optical design problem being limited by human innovation in the search for new applications and the fabrication issue being limited by the availability of resources required to improve fabrication capabilities. With respect to the industry, the current marketplace does not favor binary optics as a separate product line and so we expect that companies whose primary purpose is the production of binary optics will not represent the bulk of binary optics production. Rather, binary optics' more natural role is as an enabling technology - a technology which will directly result in a competitive advantage in a company's other business areas - and so we expect that the majority of binary optics will be produced for internal use.

  1. Binary optics: Trends and limitations

    NASA Astrophysics Data System (ADS)

    Farn, Michael W.; Veldkamp, Wilfrid B.

    1993-08-01

    We describe the current state of binary optics, addressing both the technology and the industry (i.e., marketplace). With respect to the technology, the two dominant aspects are optical design methods and fabrication capabilities, with the optical design problem being limited by human innovation in the search for new applications and the fabrication issue being limited by the availability of resources required to improve fabrication capabilities. With respect to the industry, the current marketplace does not favor binary optics as a separate product line and so we expect that companies whose primary purpose is the production of binary optics will not represent the bulk of binary optics production. Rather, binary optics' more natural role is as an enabling technology - a technology which will directly result in a competitive advantage in a company's other business areas - and so we expect that the majority of binary optics will be produced for internal use.

  2. Deep, Low Mass Ratio Overcontact Binary Systems. V. The Lowest Mass Ratio Binary V857 Herculis

    NASA Astrophysics Data System (ADS)

    Qian, S.-B.; Zhu, L.-Y.; Soonthornthum, B.; Yuan, J.-Z.; Yang, Y.-G.; He, J.-J.

    2005-09-01

    Charge-coupled device (CCD) photometric light curves in the B, V, and R bands of the complete eclipsing binary star V857 Her are presented. It is shown that the light curves of the W UMa-type binary are symmetric and of A type according to Binnendijk's classification. Our four epochs of light minimum along with others compiled from the literature were used to revise the period and study the period change. Weak evidence indicates that the orbital period of V857 Her may show a continuous increase at a rate of dP/dt=+2.90×10-7 days yr-1. The photometric parameters of the system were determined with the 2003 version of the Wilson-Devinney code. It is shown that V857 Her is a deep overcontact binary system with f=83.8%+/-5.1%. The derived mass ratio of q=0.06532+/-0.0002 suggests that it has the lowest mass ratio among overcontact binary systems. As the orbital period increases, the decrease of the mass ratio will cause it to evolve into a single rapidly rotating star when it meets the more familiar criterion that the orbital angular momentum be less than 3 times the total spin angular momentum. To understand the evolutionary state of the system, long-term photometric monitoring and spectroscopic observations will be required.

  3. Spinodal decomposition of chemically reactive binary mixtures

    NASA Astrophysics Data System (ADS)

    Lamorgese, A.; Mauri, R.

    2016-08-01

    We simulate the influence of a reversible isomerization reaction on the phase segregation process occurring after spinodal decomposition of a deeply quenched regular binary mixture, restricting attention to systems wherein material transport occurs solely by diffusion. Our theoretical approach follows a diffuse-interface model of partially miscible binary mixtures wherein the coupling between reaction and diffusion is addressed within the frame of nonequilibrium thermodynamics, leading to a linear dependence of the reaction rate on the chemical affinity. Ultimately, the rate for an elementary reaction depends on the local part of the chemical potential difference since reaction is an inherently local phenomenon. Based on two-dimensional simulation results, we express the competition between segregation and reaction as a function of the Damköhler number. For a phase-separating mixture with components having different physical properties, a skewed phase diagram leads, at large times, to a system converging to a single-phase equilibrium state, corresponding to the absolute minimum of the Gibbs free energy. This conclusion continues to hold for the critical phase separation of an ideally perfectly symmetric binary mixture, where the choice of final equilibrium state at large times depends on the initial mean concentration being slightly larger or less than the critical concentration.

  4. Spinodal decomposition of chemically reactive binary mixtures.

    PubMed

    Lamorgese, A; Mauri, R

    2016-08-01

    We simulate the influence of a reversible isomerization reaction on the phase segregation process occurring after spinodal decomposition of a deeply quenched regular binary mixture, restricting attention to systems wherein material transport occurs solely by diffusion. Our theoretical approach follows a diffuse-interface model of partially miscible binary mixtures wherein the coupling between reaction and diffusion is addressed within the frame of nonequilibrium thermodynamics, leading to a linear dependence of the reaction rate on the chemical affinity. Ultimately, the rate for an elementary reaction depends on the local part of the chemical potential difference since reaction is an inherently local phenomenon. Based on two-dimensional simulation results, we express the competition between segregation and reaction as a function of the Damköhler number. For a phase-separating mixture with components having different physical properties, a skewed phase diagram leads, at large times, to a system converging to a single-phase equilibrium state, corresponding to the absolute minimum of the Gibbs free energy. This conclusion continues to hold for the critical phase separation of an ideally perfectly symmetric binary mixture, where the choice of final equilibrium state at large times depends on the initial mean concentration being slightly larger or less than the critical concentration. PMID:27627358

  5. Detecting gravity waves from binary black holes

    NASA Technical Reports Server (NTRS)

    Wahlquist, Hugo D.

    1989-01-01

    One of the most attractive possible sources of strong gravitational waves would be a binary system comprising massive black holes (BH). The gravitational radiation from a binary is an elliptically polarized, periodic wave which could be observed continuously - or at intervals whenever a detector was available. This continuity of the signal is certainly appealing compared to waiting for individual pulses from infrequent random events. It also has the advantage over pulses that continued observation can increase the signal-to-noise ratio almost indefinitely. Furthermore, this system is dynamically simple; the theory of the generation of the radiation is unambiguous; all characteristics of the signal can be precisely related to the dynamical parameters of the source. The current situation is that while there is no observational evidence as yet for the existence of massive binary BH, their formation is theoretically plausible, and within certain coupled constraints of mass and location, their existence cannot be observationally excluded. Detecting gravitational waves from these objects might be the first observational proof of their existence.

  6. Binary Stars in Globular Clusters

    NASA Astrophysics Data System (ADS)

    Mateo, M.; Murdin, P.

    2000-11-01

    Globular clusters have long been known to be among the richest stellar groupings within our Galaxy, but for many years they were believed to be largely devoid of the most minimal stellar group: binary stars (see BINARY STARS: OVERVIEW). For many years, the only evidence that any binaries existed in these clusters came from the presence of BLUE STRAGGLERS—stars that appear to be significantly you...

  7. The role of vascular capacitance in the coronary arteries.

    PubMed

    Lee, J; Chambers, D E; Akizuki, S; Downey, J M

    1984-12-01

    When the left coronary artery was perfused with nonpulsatile pressure, the onset of diastole was accompanied by a capacitance overshoot in flow with an exponential decay back to a steady state. Time constant for that decay ranged from 55 msec when tone was present to 105 msec with maximal dilation. Since the transient resulted from a fall in tissue pressure, this represents an estimation of intramural arterial capacitance only. Transients in perfusion pressure, which would also affect epicardial arteries, yielded similar time constants. We concluded that most of the coronary capacitance resides in the small intramural vessels. Analysis of transients yielded a value for capacitance of between 0.01 and 0.05 ml/mm Hg per 100 g. We then used the data from the transients to construct coronary pressure flow curves which were free of any back flow from capacitance. When coronary tone was present, the curves indicated that flow ceased at 30 mm Hg. With maximal dilation, flow ceased at only 18 mm Hg. Long diastoles in those same hearts indicated that flow ceased at about 10 mm Hg higher pressure. Although capacitance causes critical closing pressure as determined by a long diastole to be artifactually high, critical closing pressure is still appreciable in the heart, and tone dependent. Finally, three computer models were built, one of which included only small vessel capacitances, the second, only vascular waterfalls, and the third, both of the above. Only model 3 was capable of reproducing the flow patterns which were actually seen. PMID:6499131

  8. Compact Two-Liquid Microfluidic Hyperelastic Capacitive Strain Sensors

    NASA Astrophysics Data System (ADS)

    Liu, Shanliangzi; Sun, Xiaoda; Rykaczewski, Konrad

    2014-11-01

    Applications of liquid metal microfluidic devices include flexible electronics, biomedical devices, and soft robotics. In addition to single channel resistive strain sensors, two channel capacitive sensors have also been developed. However, these capacitive strain sensors have low capacitance with a footprint of about a square centimeter, making strain-output correlation quite complex. To address this issue, we developed a compact two liquid single straight channel capacitive strain sensor with a dielectric liquid sandwiched between two liquid metal electrodes. Formation of the capacitor with a liquid dielectric instead of PDMS enables capacitance increase through selection of high permittivity liquid. Using a custom experimental setup, we show that use of water and glycerol instead of silicone oil in-between the liquid metal electrodes can increase the device capacitance by fivefold. We discuss the effect of channel diameter, dielectric spacing, interfacial meniscus shape, and the liquid flow on device capacitance as well as response to strain. In addition, we discuss the effect of gallium oxide shell formation at the dielectric-liquid metal interface. KR acknowledges startup funding from ASU.

  9. Calculation of series capacitance for transient analysis of windings

    SciTech Connect

    Chowdhuri, P.

    1985-01-01

    The analysis of transient voltage oscillations inside a winding (transformer, reactor or magnet) is performed by representing the winding as a lumped ladder network. The capacitances to the return lead (or ground) C/sub gi/ can be computed by assuming either equivalent parellel-plate or cylindrical-symmetry configuration. The equivalent series capacitances of a winding C/sub si/, however, are complex capacitance networks, consisting of intra- and intercoil turn-to-turn capacitances of the coil sections. Many researchers have proposed methods of computing the equivalent series capacitance of a winding. As each method is quite different from the others, the analysis of the transient behavior of a winding becomes uncertain. A method of computing the series capacitance of a winding is proposed which is mathematically rigorous but simple to execute. As a check, the equivalent series capacitance of a four-turn double-disk winding was computed by the proposed method as well as by simple circuit analysis. The computations corraborated each other.

  10. Capacitance-level/density monitor for fluidized-bed combustor

    DOEpatents

    Fasching, George E.; Utt, Carroll E.

    1982-01-01

    A multiple segment three-terminal type capacitance probe with segment selection, capacitance detection and compensation circuitry and read-out control for level/density measurements in a fluidized-bed vessel is provided. The probe is driven at a high excitation frequency of up to 50 kHz to sense quadrature (capacitive) current related to probe/vessel capacitance while being relatively insensitive to the resistance current component. Compensation circuitry is provided for generating a negative current of equal magnitude to cancel out only the resistive component current. Clock-operated control circuitry separately selects the probe segments in a predetermined order for detecting and storing this capacitance measurement. The selected segment acts as a guarded electrode and is connected to the read-out circuitry while all unselected segments are connected to the probe body, which together form the probe guard electrode. The selected probe segment capacitance component signal is directed to a corresponding segment channel sample and hold circuit dedicated to that segment to store the signal derived from that segment. This provides parallel outputs for display, computer input, etc., for the detected capacitance values. The rate of segment sampling may be varied to either monitor the dynamic density profile of the bed (high sampling rate) or monitor average bed characteristics (slower sampling rate).

  11. A new physical interpretation of plant root capacitance

    PubMed Central

    Bengough, Anthony G.

    2012-01-01

    Capacitance has been used as a non-destructive measure of root system size for 30 years. The equipment required is cheap and simple to apply in both field and laboratory. Good linear correlations have been reported between capacitance and root mass. A model by F. N. Dalton, predicting a linear relationship between these two variables, has become accepted widely. This model was tested for barley (Hordeum vulgare) grown hydroponically using treatments that included: raising roots out of solution, cutting roots at positions below the solution surface, and varying the distance between plant electrode and the solution surface. Although good linear correlations were found between capacitance and mass for whole root systems, when roots were raised out of solution capacitances were not linearly related to submerged root mass. Excision of roots in the solution had negligible effect on the measured capacitance. These latter observations conflict with Dalton’s model. Capacitance correlated linearly with the sum of root cross-sectional areas at the solution surface and inversely with distance between plant electrode and solution surface. A new model for capacitance is proposed that is consistent with these observations. PMID:23028023

  12. Evolution of Close Binary Systems

    SciTech Connect

    Yakut, K; Eggleton, P

    2005-01-24

    We collected data on the masses, radii, etc. of three classes of close binary stars: low-temperature contact binaries (LTCBs), near-contact binaries (NCBs), and detached close binaries (DCBs). They restrict themselves to systems where (1) both components are, at least arguably, near the Main Sequence, (2) the periods are less than a day, and (3) there is both spectroscopic and photometric analysis leading to reasonably reliable data. They discuss the possible evolutionary connections between these three classes, emphasizing the roles played by mass loss and angular momentum loss in rapidly-rotating cool stars.

  13. Low autocorrelation binary sequences

    NASA Astrophysics Data System (ADS)

    Packebusch, Tom; Mertens, Stephan

    2016-04-01

    Binary sequences with minimal autocorrelations have applications in communication engineering, mathematics and computer science. In statistical physics they appear as groundstates of the Bernasconi model. Finding these sequences is a notoriously hard problem, that so far can be solved only by exhaustive search. We review recent algorithms and present a new algorithm that finds optimal sequences of length N in time O(N {1.73}N). We computed all optimal sequences for N≤slant 66 and all optimal skewsymmetric sequences for N≤slant 119.

  14. BINARY STORAGE ELEMENT

    DOEpatents

    Chu, J.C.

    1958-06-10

    A binary storage device is described comprising a toggle provided with associsted improved driver circuits adapted to produce reliable action of the toggle during clearing of the toggle to one of its two states. or transferring information into and out of the toggle. The invention resides in the development of a self-regulating driver circuit to minimize the fluctuation of the driving voltages for the toggle. The disclosed driver circuit produces two pulses in response to an input pulse: a first or ''clear'' pulse beginning nt substantially the same time but endlrg slightly sooner than the second or ''transfer'' output pulse.

  15. The ζ Aurigae Binaries

    NASA Astrophysics Data System (ADS)

    Griffin, R. Elizabeth; Ake, Thomas B.

    This opening chapter provides a brief historical overview of the ζ Aur stars, with a focus on what K.O. Wright, his predecessors and colleagues at the Dominion Astrophysical Observatory, and his contemporaries further afield, achieved during the era of pre-electronic data. It places the topic within the framework of modern observing, data management and computing, outlines the principal features of the chromospheric-eclipse phenomena which single out the ζ Aur binaries for special study, and describes the considerable potential which this remarkable yet very select group of stars offers for increasing our understanding of stellar physics.

  16. Binary porous convection

    NASA Astrophysics Data System (ADS)

    Carey, Michael Richard

    Binary porous convection falls into the larger category of pattern formation---a symmetry breaking instability which creates a spatially periodic structure within a homogeneous system. The experiments and model presented in this dissertation indicate that an essential piece of physics is missing from the standard Darcian picture used to describe pattern formation in a porous medium convection system. Present theory predicts a bifurcation to an oscillatory state at onset for a binary mixture in a porous media over a wide range of experimental parameters (Brand and Steinberg, Physics Letters 93A 333 (1983)). This theory is inadequate in explaining the predominant large amplitude, backward, stationary overturning convection state observed in our experiments after transients have decayed. Convection experiments were visualized with magnetic resonance imaging and performed with a foam medium in slot and cylindrical geometries as well as a rectangular, packed bead system with water-ethanol mixtures. We explore the possibility that the difference between theory and experiment is due to enhanced solutal mixing not included in previous theories. The enhanced mixing of the fluid produces an effective diffusion coefficient that largely suppresses gradients in the concentration field, resulting in single-fluid like behavior. We model the experimental system with a Lorenz truncation of the binary Darcy equations with enhanced mixing. This model predicts results qualitatively similar to experiments: a forward bifurcation to small amplitude oscillations with a secondary backward bifurcation to large amplitude stationary convection. We have also developed an experimental nuclear magnetic resonance technique that measures the effective diffusion coefficient, D = D(v), as a function of velocity, v, for the individual species of the binary mixture simultaneously. However, the mixing effect measured in plug flow experiments is roughly two to three orders of magnitude too small to have

  17. Bloch inductance in small-capacitance Josephson junctions.

    PubMed

    Zorin, A B

    2006-04-28

    We show that the electrical impedance of a small-capacitance Josephson junction also includes, in addition to the capacitive term -i/(omega)CB, an inductive term i(omega)LB. Similar to the known Bloch capacitance CB(q), the Bloch inductance LB(q) also depends periodically on the quasicharge, q, and its maximum value achieved at q=e(mod 2e) always exceeds the value of the Josephson inductance of this junction LJ(phi) at fixed phi=0. The effect of the Bloch inductance on the dynamics of a single junction and a one-dimensional array is described.

  18. Flexible transparent iontronic film for interfacial capacitive pressure sensing.

    PubMed

    Nie, Baoqing; Li, Ruya; Cao, Jennifer; Brandt, James D; Pan, Tingrui

    2015-10-21

    A flexible, transparent iontronic film is introduced as a thin-film capacitive sensing material for emerging wearable and health-monitoring applications. Utilizing the capacitive interface at the ionic-electronic contact, the iontronic film sensor offers a large unit-area capacitance (of 5.4 μF cm(-2) ) and an ultrahigh sensitivity (of 3.1 nF kPa(-1) ), which is a thousand times greater than that of traditional solid-state counterparts. PMID:26333011

  19. Controlled synthesis of MnSn(OH){sub 6}/graphene nanocomposites and their electrochemical properties as capacitive materials

    SciTech Connect

    Wang Gongkai; Sun Xiang; Lu Fengyuan; Yu Qingkai; Liu Changsheng; Lian Jie

    2012-01-15

    We report the synthesis of novel MnSn(OH){sub 6}/graphene nanocomposites produced by a co-precipitation method and their potential application for electrochemical energy storage. The hydroxide decorated graphene nanocomposites display better performance over pure MnSn(OH){sub 6} nanoparticles because the graphene sheets act as conductive bridges improving the ionic and electronic transport. The crystallinity of MnSn(OH){sub 6} nanoparticles deposited on the surface of graphene sheets also impacts the capacitive properties as electrodes. The maximum capacitance of 31.2 F/g (59.4 F/g based on the mass of MnSn(OH){sub 6} nanoparticles) was achieved for the sample with a low degree of crystallinity. No significant degradation of capacitance occurred after 500 cycles at a current density of 1.5 A/g in 1 M Na{sub 2}SO{sub 4} aqueous solution, indicating an excellent electrochemical stability. The results serve as an example demonstrating the potential of integrating highly conductive graphene networks into binary metal hydroxide in improving the performance of active electrode materials for electrochemical energy storage applications. - Graphical abstract: Graphite oxide (GO) can be synthesized by oxidizing graphite using Hummers method. Graphene was reduced from GO by thermal exfoliation. In this work, MnSn(OH){sub 6}/graphene nano-composites were synthesized by a simple co-precipitation method and their electrochemical performances have been explored. Highlights: Black-Right-Pointing-Pointer Noval MnSn(OH){sub 6}/graphene nano-composites were synthesized. Black-Right-Pointing-Pointer Microstructure can be tailored by changing the reaction temperature and time. Black-Right-Pointing-Pointer Crystallinity of MnSn(OH){sub 6} nanoparticles impacts capacitive properties as electrode. Black-Right-Pointing-Pointer Nano-composites display improved electrochemical performance over MnSn(OH){sub 6} alone. Black-Right-Pointing-Pointer Results serve as an example demonstrating the

  20. SECULAR EVOLUTION OF BINARIES NEAR MASSIVE BLACK HOLES: FORMATION OF COMPACT BINARIES, MERGER/COLLISION PRODUCTS AND G2-LIKE OBJECTS

    SciTech Connect

    Prodan, Snezana; Antonini, Fabio; Perets, Hagai B. E-mail: antonini@cita.utoronto.ca

    2015-02-01

    Here we discuss the evolution of binaries around massive black holes (MBHs) in nuclear stellar clusters. We focus on their secular evolution due to the perturbation by the MBHs, while simplistically accounting for their collisional evolution. Binaries with highly inclined orbits with respect to their orbits around MBHs are strongly affected by secular processes, which periodically change their eccentricities and inclinations (e.g., Kozai-Lidov cycles). During periapsis approach, dissipative processes such as tidal friction may become highly efficient, and may lead to shrinkage of a binary orbit and even to its merger. Binaries in this environment can therefore significantly change their orbital evolution due to the MBH third-body perturbative effects. Such orbital evolution may impinge on their later stellar evolution. Here we follow the secular dynamics of such binaries and its coupling to tidal evolution, as well as the stellar evolution of such binaries on longer timescales. We find that stellar binaries in the central parts of nuclear stellar clusters (NSCs) are highly likely to evolve into eccentric and/or short-period binaries, and become strongly interacting binaries either on the main sequence (at which point they may even merge), or through their later binary stellar evolution. The central parts of NSCs therefore catalyze the formation and evolution of strongly interacting binaries, and lead to the enhanced formation of blue stragglers, X-ray binaries, gravitational wave sources, and possible supernova progenitors. Induced mergers/collisions may also lead to the formation of G2-like cloud-like objects such as the one recently observed in the Galactic center.

  1. Protein kinase C activates non-capacitative calcium entry in human platelets

    PubMed Central

    Rosado, Juan A; Sage, Stewart O

    2000-01-01

    In many non-excitable cells Ca2+ influx is mainly controlled by the filling state of the intracellular Ca2+ stores. It has been suggested that this store-mediated or capacitative Ca2+ entry is brought about by a physical and reversible coupling of the endoplasmic reticulum with the plasma membrane. Here we provide evidence for an additional, non-capacitative Ca2+ entry mechanism in human platelets. Changes in cytosolic Ca2+ and Sr2+ were measured in human platelets loaded with the fluorescent indicator fura-2. Depletion of the internal Ca2+ stores with thapsigargin plus a low concentration of ionomycin stimulated store-mediated cation entry, as demonstrated upon Ca2+ or Sr2+ addition. Subsequent treatment with thrombin stimulated further divalent cation entry in a concentration-dependent manner. Direct activation of protein kinase C (PKC) by phorbol-12-myristate-13-acetate or 1-oleoyl-2-acetyl-sn-glycerol also stimulated divalent cation entry, without evoking the release of Ca2+ from intracellular stores. Cation entry evoked by thrombin or activators of PKC was abolished by the PKC inhibitor Ro-31-8220. Unlike store-mediated Ca2+ entry, jasplakinolide, which reorganises actin filaments into a tight cortical layer adjacent to the plasma membrane, did not inhibit divalent cation influx evoked by thrombin when applied after Ca2+ store depletion, or by activators of PKC. Thrombin also activated Ca2+ entry in platelets in which the release from intracellular stores and store-mediated Ca2+ entry were blocked by xestospongin C. These results indicate that the non-capacitative divalent cation entry pathway is regulated independently of store-mediated entry and does not require coupling of the endoplasmic reticulum and the plasma membrane. These results support the existence of a mechanism for receptor-evoked Ca2+ entry in human platelets that is independent of Ca2+ store depletion. This Ca2+ entry mechanism may be activated by occupation of G-protein-coupled receptors

  2. Black Hole - Neutron Star Binary Simulations at Georgia Tech

    NASA Astrophysics Data System (ADS)

    Haas, Roland

    2009-05-01

    Mixed compact object binaries consisting of a black hole and a neutron star are expected to be not only one of the primary sources of gravitational radiation to be observed by interferometric detectors but also the central engine of short gamma-ray bursts. We report on the status of our effort at Georgia Tech to model these mixed binary systems using the moving puncture method. The results are obtained with an enhanced version our vacuum MayaKranc code coupled to the hydrodynamics Whisky code. We present preliminary results of gravitational waveforms and the disruption of the neutron star for simple polytropic equations of state.

  3. Mechano-capacitive properties of polarized membranes.

    PubMed

    Mosgaard, Lars D; Zecchi, Karis A; Heimburg, Thomas

    2015-10-28

    Biological membranes are capacitors that can be charged by applying a field across the membrane. The charges on the capacitor exert a force on the membrane that leads to electrostriction, i.e. a thinning of the membrane. Since the force is quadratic in voltage, negative and positive voltage have an identical influence on the physics of symmetric membranes. However, this is not the case for a membrane with an asymmetry leading to a permanent electric polarization. Positive and negative voltages of identical magnitude lead to different properties. Such an asymmetry can originate from a lipid composition that is different on the two monolayers of the membrane, or from membrane curvature. The latter effect is called 'flexoelectricity'. As a consequence of permanent polarization, the membrane capacitor is discharged at a voltage different from zero. This leads to interesting electrical phenomena such as outward or inward rectification of membrane permeability. Here, we introduce a generalized theoretical framework, that treats capacitance, polarization, flexoelectricity, piezoelectricity and thermoelectricity in the same language. We show applications to electrostriction, membrane permeability and piezoelectricity and thermoelectricity close to melting transitions, where such effects are especially pronounced. PMID:26324950

  4. An uncooled capacitive sensor for IR detection

    NASA Astrophysics Data System (ADS)

    Siebke, Georg; Gerngroß, Kathrin; Holik, Peter; Schmitz, Sam; Rohloff, Markus; Tätzner, Simon; Steltenkamp, Siegfried

    2014-06-01

    The beetle Melanophila acuminata detects forest fires from distances as far as 80 miles away. To accomplish this, the beetle uses highly specific IR receptors with a diameter of approximately 15 μm. These receptors are mechanoreceptors that detect deformations induced by the absorption of radiation. Although the detection mechanism is understood in principle, it is still unclear how the beetle reaches such high sensitivity. In this work, we present the biomimetic approach of an uncooled IR sensor based on the beetle's receptors. This sensor is based on a fluid-filled pressure cell and operates at room temperature. Upon absorbing IR radiation, the fluid heats up and expands. The expanding fluid deflects one electrode of a plate capacitor. By measuring the change in capacitance, the volume increase and the absorbed energy can be inferred. To prevent the risk of damage at high energy absorption, a compensation mechanism is presented in this work. The mechanism prevents large but slow volume changes inside the pressure cell by a microfluidic connection of the pressure cell with a compensation chamber. The channel and the compensation chamber act as a microfluidic low-pass filter and do not affect the overall sensitivity above an appropriate cut-off frequency. Using MEMS technology, we are able to incorporate the complete system into a silicon chip with an area of a few mm2. Here, we show a proof-of-concept and first measurements of the sensor.

  5. Energy recovery in membrane capacitive deionization.

    PubMed

    Długołęcki, Piotr; van der Wal, Albert

    2013-05-01

    Membrane capacitive deionization (MCDI) is a water desalination technology based on applying a cell voltage between two oppositely placed porous carbon electrodes. In front of each electrode, an ion-exchange membrane is positioned, and between them, a spacer is situated, which transports the water to be desalinated. In this work, we demonstrate for the first time that up to 83% of the energy used for charging the electrodes during desalination can be recovered in the regeneration step. This can be achieved by charging and discharging the electrodes in a controlled manner by using constant current conditions. By implementing energy recovery as an integral part of the MCDI operation, the overall energy consumption can be as low as 0.26 (kW·h)/m(3) of produced water to reduce the salinity by 10 mM, which means that MCDI is more energy efficient for treatment of brackish water than reverse osmosis. Nevertheless, the measured energy consumption is much higher than the thermodynamically calculated values for desalinating the water, and therefore, a further improvement in thermodynamic efficiency will be needed in the future.

  6. Multilevel Models for Binary Data

    ERIC Educational Resources Information Center

    Powers, Daniel A.

    2012-01-01

    The methods and models for categorical data analysis cover considerable ground, ranging from regression-type models for binary and binomial data, count data, to ordered and unordered polytomous variables, as well as regression models that mix qualitative and continuous data. This article focuses on methods for binary or binomial data, which are…

  7. A capacitive ECG array with visual patient feedback.

    PubMed

    Eilebrecht, Benjamin; Schommartz, Antje; Walter, Marian; Wartzek, Tobias; Czaplik, Michael; Leonhardt, Steffen

    2010-01-01

    Capacitive electrocardiogram (ECG) sensing is a promising technique for less constraining vital signal measurement and close to a commercial application. Even bigger trials testing the diagnostic significance were already done with single lead systems. Anyway, most applications to be found in research are limited to one channel and thus limited in its diagnostic relevance as only diseases coming along with a change of the heart rate can be diagnosed adequately. As a consequence the need for capacitive multi-channel ECGs combining the diagnostic relevance and the advantages of capacitive ECG sensing emerges. This paper introduces a capacitive ECG measurement system which allows the recording of standardized ECG leads according to Einthoven and Goldberger by means of an electrode array with nine electrodes.

  8. Structure and Capacitance of Electrical Double Layers inside Micropores

    NASA Astrophysics Data System (ADS)

    Feng, Guang; Qiao, Rui; Huang, Jingsong; Sumpter, Bobby G.; Meunier, Vincent

    2010-03-01

    Recent experiments indicate that the specific capacitance of micropores (diameter less than 2nm) increases anomalously as the pore size decreases^[1]. To understand the physical origin of this discovery, we performed a series of molecular dynamics simulations to study the electrical double layers (EDLs) in micropores with different shapes (tube vs slit) and pore sizes (0.668nm - 3.342nm). Several different aqueous electrolytes (K^+, Na^+, Cl^-, and F^- in water) were used in these micropores. We quantified the structure of EDLs inside the pores, and computed the capacitance of EDLs. The scaling of capacitance shows a qualitative agreement with the experimental observations. We attribute the anomalous enhancement of capacitance in micropores to the short-range ionelectrode and ionsolvent interactions.[1] J. Chmiola, G. Yushin, Y. Gogotsi, C. Portet, P. Simon, and P.L. Taberna, Science 2006, 313, 1760.

  9. Enhancement of the carbon electrode capacitance by brominated hydroquinones

    NASA Astrophysics Data System (ADS)

    Gastol, Dominika; Walkowiak, Jedrzej; Fic, Krzysztof; Frackowiak, Elzbieta

    2016-09-01

    This paper presents supercapacitors utilizing new redox-active electrolytes with bromine species. Two sources of Br specimen were investigated, i.e. dibromodihydroxybenzene dissolved in KOH and potassium bromide dissolved in KOH with hydroxybenzene additive. KOH-activated carbon, exhibiting a well-developed porosity, was incorporated as an electrode material. The tested systems revealed a capacitance enhancement explained by Br- and partial BrO3- redox activity. The optimisation of the electrolyte concentration resulted in a capacitance value of 314 F g-1 achieved at 1.1 V voltage range. Good cyclability performance (11% capacitance loss) combined with a high capacitance value (244 F g-1) were obtained for the system operating in 0.2 mol L- 1 C6H4Br2O2 in 2 mol L-1 KOH electrolytic solution.

  10. Fringe Capacitance of a Parallel-Plate Capacitor.

    ERIC Educational Resources Information Center

    Hale, D. P.

    1978-01-01

    Describes an experiment designed to measure the forces between charged parallel plates, and determines the relationship among the effective electrode area, the measured capacitance values, and the electrode spacing of a parallel plate capacitor. (GA)

  11. Capacitance-Power-Hysteresis Trilemma in Nanoporous Supercapacitors

    NASA Astrophysics Data System (ADS)

    Lee, Alpha A.; Vella, Dominic; Goriely, Alain; Kondrat, Svyatoslav

    2016-04-01

    Nanoporous supercapacitors are an important player in the field of energy storage that fill the gap between dielectric capacitors and batteries. The key challenge in the development of supercapacitors is the perceived trade-off between capacitance and power delivery. Current efforts to boost the capacitance of nanoporous supercapacitors focus on reducing the pore size so that they can only accommodate a single layer of ions. However, this tight packing compromises the charging dynamics and hence power density. We show via an analytical theory and Monte Carlo simulations that charging is sensitively dependent on the affinity of ions to the pores, and that high capacitances can be obtained for ionophobic pores of widths significantly larger than the ion diameter. Our theory also predicts that charging can be hysteretic with a significant energy loss per cycle for intermediate ionophilicities. We use these observations to explore the parameter regimes in which a capacitance-power-hysteresis trilemma may be avoided.

  12. The Evolutionary Outcomes of Expansive Binary Asteroid Systems

    NASA Astrophysics Data System (ADS)

    McMahon, Jay W.

    2016-10-01

    Singly synchronous binary asteroid systems have several evolutionary end-states, which depend heavily on the BYORP effect. In the case of expansive BYORP, the binary system could evolve to become a wide asynchronous binary system (Jacobson, et al 2014), or the system could expand far enough to become disrupted to form a heliocentric pair (Vokrouhlicky et al 2008). Cuk et al (2011) found that upon expanding the secondary will quickly become asynchronous, and will end up re-establishing synchronous rotation with the opposite attitude, causing the binary orbit to subsequently contract. The distinction between these outcomes depends on whether the secondary asteroid stays synchronized, which keeps the BYORP effect active and the orbit expanding. As the orbit expands, the secondary libratation will expand, and the libration will also causes large variations in the binary orbit due to the elongation of the secondary. If the eccentricity and libration are bound to small enough values the system can expand significantly. This work discusses the stability of the libration and orbital motion as a binary expands from a wide variety of simulation runs with various parameters. We investigate how the strength of tides and BYORP change the stability of the librational motion; an important factor is the speed of BYORP expansion as slower expansion allows tides to have a more stabilizing effect. We also investigate the effect of heliocentric orbit semimajor axis and eccentricity. We find that resonances between the coupled orbit-libration frequencies and the heliocentric orbit cause instability in the binary orbit eccentricity which produces a strong preference for wide binary production, especially amongst retrograde binary systems. This instability also becomes stronger with large heliocentric eccentricities. Prograde binaries are more stable and can possible grow to become asteroid pairs. We find that even in the presence of tides, reestablishment of synchronous spin into a

  13. Signature Visualization of Software Binaries

    SciTech Connect

    Panas, T

    2008-07-01

    In this paper we present work on the visualization of software binaries. In particular, we utilize ROSE, an open source compiler infrastructure, to pre-process software binaries, and we apply a landscape metaphor to visualize the signature of each binary (malware). We define the signature of a binary as a metric-based layout of the functions contained in the binary. In our initial experiment, we visualize the signatures of a series of computer worms that all originate from the same line. These visualizations are useful for a number of reasons. First, the images reveal how the archetype has evolved over a series of versions of one worm. Second, one can see the distinct changes between version. This allows the viewer to form conclusions about the development cycle of a particular worm.

  14. Capacitive Sensors for Measuring Masses of Cryogenic Fluids

    NASA Technical Reports Server (NTRS)

    Nurge, Mark; Youngquist, Robert

    2003-01-01

    An effort is under way to develop capacitive sensors for measuring the masses of cryogenic fluids in tanks. These sensors are intended to function in both microgravitational and normal gravitational settings, and should not be confused with level sensors, including capacitive ones. A sensor of this type is conceptually simple in the sense that (1) it includes only one capacitor and (2) if properly designed, its single capacitance reading should be readily convertible to a close approximation of the mass of the cryogenic fluid in the tank. Consider a pair of electrically insulated electrodes used as a simple capacitive sensor. In general, the capacitance is proportional to the permittivity of the dielectric medium (in this case, a cryogenic fluid) between the electrodes. The success of design and operation of a sensor of the present type depends on the accuracy of the assumption that to a close approximation, the permittivity of the cryogenic fluid varies linearly with the density of the fluid. Data on liquid nitrogen, liquid oxygen, and liquid hydrogen, reported by the National Institute of Standards and Technology, indicate that the permittivities and densities of these fluids are, indeed, linearly related to within a few tenths of a percent over the pressure and temperature regions of interest. Hence, ignoring geometric effects for the moment, the capacitance between two electrodes immersed in the fluid should vary linearly with the density, and, hence, with the mass of the fluid. Of course, it is necessary to take account of the tank geometry. Because most cryogenic tanks do not have uniform cross sections, the readings of level sensors, including capacitive ones, are not linearly correlated with the masses of fluids in the tanks. In a sensor of the present type, the capacitor electrodes are shaped so that at a given height, the capacitance per unit height is approximately proportional to the cross-sectional area of the tank in the horizontal plane at that

  15. Current Progress of Capacitive Deionization for Removal of Pollutant Ions

    NASA Astrophysics Data System (ADS)

    Gaikwad, Mahendra S.; Balomajumder, Chandrajit

    2016-08-01

    A mini review of a recently developing water purification technology capacitive deionization (CDI) applied for removal of pollutant ions is provided. The current progress of CDI for removal of different pollutant ions such as arsenic, fluoride, boron, phosphate, lithium, copper, cadmium, ferric, and nitrate ions is presented. This paper aims at motivating new research opportunities in capacitive deionization technology for removal of pollutant ions from polluted water.

  16. Probing Quantum Capacitance in a 3D Topological Insulator

    NASA Astrophysics Data System (ADS)

    Kozlov, D. A.; Bauer, D.; Ziegler, J.; Fischer, R.; Savchenko, M. L.; Kvon, Z. D.; Mikhailov, N. N.; Dvoretsky, S. A.; Weiss, D.

    2016-04-01

    We measure the quantum capacitance and probe thus directly the electronic density of states of the high mobility, Dirac type two-dimensional electron system, which forms on the surface of strained HgTe. Here we show that observed magnetocapacitance oscillations probe—in contrast to magnetotransport—primarily the top surface. Capacitance measurements constitute thus a powerful tool to probe only one topological surface and to reconstruct its Landau level spectrum for different positions of the Fermi energy.

  17. Anomalous low-frequency grain-boundary capacitance in silicon

    NASA Astrophysics Data System (ADS)

    Seager, C. H.; Pike, G. E.

    1980-10-01

    The admittance of silicon bicrystals has been measured as a function of temperature, frequency, and dc voltage. In some cases the low-frequency capacitance is anomalously large. The ac response of a simple double depletion layer structure is calculated. The anomalous capacitive currents are due to an out-of-phase modulation of the barrier height caused by charge injected into grain-boundary traps.

  18. BINARY ASTROMETRIC MICROLENSING WITH GAIA

    SciTech Connect

    Sajadian, Sedighe

    2015-04-15

    We investigate whether or not Gaia can specify the binary fractions of massive stellar populations in the Galactic disk through astrometric microlensing. Furthermore, we study whether or not some information about their mass distributions can be inferred via this method. In this regard, we simulate the binary astrometric microlensing events due to massive stellar populations according to the Gaia observing strategy by considering (i) stellar-mass black holes, (ii) neutron stars, (iii) white dwarfs, and (iv) main-sequence stars as microlenses. The Gaia efficiency for detecting the binary signatures in binary astrometric microlensing events is ∼10%–20%. By calculating the optical depth due to the mentioned stellar populations, the numbers of the binary astrometric microlensing events being observed with Gaia with detectable binary signatures, for the binary fraction of about 0.1, are estimated to be 6, 11, 77, and 1316, respectively. Consequently, Gaia can potentially specify the binary fractions of these massive stellar populations. However, the binary fraction of black holes measured with this method has a large uncertainty owing to a low number of the estimated events. Knowing the binary fractions in massive stellar populations helps with studying the gravitational waves. Moreover, we investigate the number of massive microlenses for which Gaia specifies masses through astrometric microlensing of single lenses toward the Galactic bulge. The resulting efficiencies of measuring the mass of mentioned populations are 9.8%, 2.9%, 1.2%, and 0.8%, respectively. The numbers of their astrometric microlensing events being observed in the Gaia era in which the lens mass can be inferred with the relative error less than 0.5 toward the Galactic bulge are estimated as 45, 34, 76, and 786, respectively. Hence, Gaia potentially gives us some information about the mass distribution of these massive stellar populations.

  19. Second post-Newtonian Lagrangian dynamics of spinning compact binaries

    NASA Astrophysics Data System (ADS)

    Huang, Li; Wu, Xin; Ma, DaZhu

    2016-09-01

    The leading-order spin-orbit coupling is included in a post-Newtonian Lagrangian formulation of spinning compact binaries, which consists of the Newtonian term, first post-Newtonian (1PN) and 2PN non-spin terms and 2PN spin-spin coupling. This leads to a 3PN spin-spin coupling occurring in the derived Hamiltonian. The spin-spin couplings are mainly responsible for chaos in the Hamiltonians. However, the 3PN spin-spin Hamiltonian is small and has different signs, compared with the 2PN spin-spin Hamiltonian equivalent to the 2PN spin-spin Lagrangian. As a result, the probability of the occurrence of chaos in the Lagrangian formulation without the spin-orbit coupling is larger than that in the Lagrangian formulation with the spin-orbit coupling. Numerical evidences support this claim.

  20. Capacitive Ultrasonic Transducer Development for Acoustic Anemometry on Mars

    NASA Astrophysics Data System (ADS)

    Leonard-Pugh, Eurion; Wilson, C.; Calcutt, S.; Davis, L.

    2012-10-01

    Previous Mars missions have used either mechanical or thermal anemometry techniques. The moving parts of mechanical anemometers are prone to damage during launch and landing and their inertia makes them unsuited for turbulence studies. Thermal anemometers have been used successfully on Mars but are difficult to calibrate and susceptible to varying ambient temperatures. In ultrasonic anemometry, wind speed and sound speed are calculated from two-way time-of-flight measurements between pairs of transducers; three pairs of transducers are used to return a 3-D wind vector. These high-frequency measurements are highly reliable and immune from drift. Piezo-electric ultrasonic anemometers are widely used on Earth due to their full-range accuracy and high measurement frequency. However these transducers have high acoustic impedances and would not work on Mars. We are developing low-mass capacitive ultrasonic transducers for Mars missions which have significantly lower acoustic impedances and would therefore have a much stronger coupling to the Martian atmosphere. These transducers consist of a metallised polymer film pulled taught against a machined metal backplane. The film is drawn towards the backplane by a DC bias voltage. A varying signal is used on top of the DC bias to oscillate the film; generating acoustic waves. This poster will look at the operation of such sensors and the developments necessary to operate the devices under Martian conditions. Transducer performance is determined primarily by two elements; the front film and the backplane. The sensitivity of the transducer is affected by the thickness of the front film; as well as the diameter, curvature and roughness of the metal backplane. We present data on the performance of the sensors and instrument design considerations including signal shapes and transducer arrangements.