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Sample records for capacitively coupled binary

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. Hydrogen atom kinetics in capacitively coupled plasmas

    NASA Astrophysics Data System (ADS)

    Nunomura, Shota; Katayama, Hirotaka; Yoshida, Isao

    2017-05-01

    Hydrogen (H) atom kinetics has been investigated in capacitively coupled very high frequency (VHF) discharges at powers of 16-780 mW cm-2 and H2 gas pressures of 0.1-2 Torr. The H atom density has been measured using vacuum ultra violet absorption spectroscopy (VUVAS) with a micro-discharge hollow cathode lamp as a VUV light source. The measurements have been performed in two different electrode configurations of discharges: conventional parallel-plate diode and triode with an intermediate mesh electrode. We find that in the triode configuration, the H atom density is strongly reduced across the mesh electrode. The H atom density varies from ˜1012 cm-3 to ˜1010 cm-3 by crossing the mesh with 0.2 mm in thickness and 36% in aperture ratio. The fluid model simulations for VHF discharge plasmas have been performed to study the H atom generation, diffusion and recombination kinetics. The simulations suggest that H atoms are generated in the bulk plasma, by the electron impact dissociation (e + H2 \\to e + 2H) and the ion-molecule reaction (H2 + + H2 \\to {{{H}}}3+ + H). The diffusion of H atoms is strongly limited by a mesh electrode, and thus the mesh geometry influences the spatial distribution of the H atoms. The loss of H atoms is dominated by the surface recombination.

  6. 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.

  7. Surface coupling effects on the capacitance of thin insulating films

    NASA Astrophysics Data System (ADS)

    Jamali, Tayeb; Farahani, S. Vasheghani; Jannesar, Mona; Palasantzas, George; Jafari, G. R.

    2015-05-01

    A general form for the surface roughness effects on the capacitance of a capacitor is proposed. We state that a capacitor with two uncoupled rough surfaces could be treated as two capacitors in series which have been divided from the mother capacitor by a slit. This is in contrast to the case where the two rough surfaces are coupled. When the rough surfaces are coupled, the type of coupling decides the modification of the capacitance in comparison to the uncoupled case. It is shown that if the coupling between the two surfaces of the capacitor is positive (negative), the capacitance is less (higher) than the case of two uncoupled rough plates. Also, we state that when the correlation length and the roughness exponent are small, the coupling effect is not negligible.

  8. Superconducting flux qubit capacitively coupled to an LC resonator

    NASA Astrophysics Data System (ADS)

    Yamamoto, T.; Inomata, K.; Koshino, K.; Billangeon, P.-M.; Nakamura, Y.; Tsai, J. S.

    2014-01-01

    We study the system where a superconducting flux qubit is capacitively coupled to an LC resonator. In three devices with different coupling capacitance, the magnitude of the dispersive shift is enhanced by the third level of the qubit and quantitatively agrees with the theory. We show by numerical calculation that the capacitive coupling plays an essential role for the enhancement in the dispersive shift. We investigate the coherence properties in two of these devices, which are in the strong-dispersive regime, and show that the qubit energy relaxation is currently not limited by the coupling. We also observe the discrete ac-Stark effect, a hallmark of the strong-dispersive regime, in accordance with the theory.

  9. Investigation of capacitively coupled ultrasonic transducer system for nondestructive evaluation.

    PubMed

    Zhong, Cheng Huan; Wilcox, Paul D; Croxford, Anthony J

    2013-12-01

    Capacitive coupling offers a simple solution to wirelessly probe ultrasonic transducers. This paper investigates the theory, feasibility, and optimization of such a capacitively coupled transducer system (CCTS) in the context of nondestructive evaluation (NDE) applications. The noncontact interface relies on an electric field formed between four metal plates-two plates are physically connected to the electrodes of a transducer, the other two are in a separate probing unit connected to the transmit/receive channel of the instrumentation. The complete system is modeled as an electric network with the measured impedance of a bonded piezoelectric ceramic disc representing a transducer attached to an arbitrary solid substrate. A transmission line model is developed which is a function of the physical parameters of the capacitively coupled system, such as the permittivity of the material between the plates, the size of the metal plates, and their relative positions. This model provides immediate prediction of electric input impedance, pulse-echo response, and the effect of plate misalignment. The model has been validated experimentally and has enabled optimization of the various parameters. It is shown that placing a tuning inductor and series resistor on the transmitting side of the circuit can significantly improve the system performance in terms of the signal-to-crosstalk ratio. Practically, bulk-wave CCTSs have been built and demonstrated for underwater and through-composite testing. It has been found that electrical conduction in the media between the plates limits their applications.

  10. 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

  11. Capacitively Coupled CMOS VCSEL Driver Circuits for Optical Communication

    NASA Astrophysics Data System (ADS)

    Kozlov, Victor

    This thesis presents the analysis, design and implementation of a common-cathode capacitively-coupled VCSEL driver in 65nm CMOS intended for short-reach optical interconnects. The driver consists of an AC-coupled high-frequency path and a low-frequency path that provides DC signal components. By increasing the low-frequency path bandwidth by 10 times compared to previous AC-coupled drivers allowed the on-chip coupling capacitor to be reduced to 2.1pF, occupying 3 times less area than prior art. The driver introduces capacitively-coupled two-tap emphasis to equalize the VCSEL's optical response. The VCSEL was modulated with an OMA of up to 5.1dBm and an ER of 9dB, measuring an RMS jitter of 5ps at a data rate of 15Gb/s, which represents the highest OMA and ER achieved in high-speed anode-driving LDDs. The driver could be programmed for a low-power mode, outputting 2.3dBm OMA at power consumption of only 30mW, corresponding to an energy efficiency of 2pJ/bit.

  12. 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.

  13. A conical air-coupled capacitance transducer for surface imaging.

    PubMed

    Hutchins, D A; Robertson, T J; Billson, D R; Solanki, P

    2003-05-01

    This paper describes the construction and operation of an air-coupled capacitance transducer with a conical backplate. This was designed to produce a focal region over an extended distance along the transducer axis. Measurements were performed to examine both the frequency response of the transducer in pulse-echo mode, and the lateral resolution for imaging purposes. The radiated field was measured and compared to theory, and the extent of the focal region determined. Images of surface topography are presented, to illustrate the range of application of the transducer.

  14. Scaling laws for dual radio-frequency capacitively coupled discharges

    SciTech Connect

    Chung, T.H.

    2005-10-01

    The characteristics of dual radio-frequency capacitively coupled discharges are studied based on a homogeneous analytic model. We are considering a planar plasma device that can be approximated using a one-dimensional model. A set of equations describing the dynamics of the system are presented and used to give the analytic scaling laws. Scaling laws relating the drive frequencies and the applied voltages of dual radio-frequency sources to operating functions such as plasma density and plasma potential are examined and compared with numerical simulations.

  15. 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.

  16. Fluid Modeling of a Very High Frequency Capacitively Coupled Reactor

    NASA Astrophysics Data System (ADS)

    Upadhyay, Rochan; Raja, Laxminarayan; Ventzek, Peter; Iwao, Toshihiko; Ishibashi, Kiyotaka; Esgee Technologies Inc. Collaboration; University of Texas at Austin Collaboration; Tokyo Electron Ltd. Collaboration

    2016-09-01

    Very High Frequency Capacitively Coupled Plasma (VHF-CCP) discharges have been studied extensively for semiconductor manufacturing applications for well over a decade. Modeling of these discharges however poses significant challenges owing to complexity associated with simulation of multiple coupled phenomena (electro-static/magnetic fields and plasma physics) over different scales and the representation of these phenomena in a computational framework. We present 2D simulations of a self-consistent plasma with the electromagnetic field represented using vector and scalar potentials. For a range of operating conditions, the ratio of capacitive and inductive power, calculated using empirical correlations available in the literature, are matched by adjusting both the electrostatic and electromagnetic fields in a decoupled manner. We present results using this model that demonstrate most of the important VHF-CCP discharge phenomena reported in the literature, such as electromagnetic wave versus electrostatic heating and its impact on plasma non-uniformity, wave resonances, etc. while realizing a practically feasible computational model.

  17. Level-set shape reconstruction of binary permittivity distributions using near-field focusing capacitance measurements

    NASA Astrophysics Data System (ADS)

    Taylor, Stephen H.; Garimella, Suresh V.

    2014-10-01

    A near-field focusing capacitance sensor consists of an array of long, coplanar electrodes offset by a small interface gap from an identical orthogonal array of electrodes. The sensor may be used to characterize permittivity inhomogeneities in thin dielectric layers. The sensor capacitance measurements represent a tessellated matrix of integral-averaged values describing void content in a series of zones corresponding to the electrode crossing points (junctions) of the sensor. The sensor does not lend itself to computed tomography because the individual capacitance measurements do not represent overlapping regions of sensitivity. An evolving level-set algorithm is proposed to reconstruct a binary permittivity distribution. A mathematical construct, based on the physics of inverse-square fields, is used to approximately reconstruct shape features too small to be captured by the raw measurements. The method accommodates the non-uniform area-sensitivity of the junction capacitance measurement. Effective use of the algorithm requires active management of the convergence criterion and evolution rate. The algorithm is demonstrated on a series of phantoms as well as measurements of a voided dielectric thermal interface material using a near-field focusing sensor.

  18. 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.

  19. Comparison of pressure dependence of electron energy distributions in oxygen capacitively and inductively coupled plasmas.

    PubMed

    Lee, Min-Hyong; Lee, Hyo-Chang; Chung, Chin-Wook

    2010-04-01

    Electron energy distribution functions (EEDFs) were measured with increasing gas pressure in oxygen capacitively and inductively coupled plasmas. It was found that, in the capacitive discharge, abnormally low-energy electrons became highly populated and the EEDF evolved to a more distinct bi-Maxwellian distribution as the gas pressure was increased. This pressure dependence of the EEDF in the oxygen capacitive discharge is contrary to argon capacitively coupled plasma, where--at high gas pressure--low-energy electrons are significantly reduced due to collisional heating and the EEDF evolves to the Maxwellian. The highly populated low-energy electrons at high gas pressure, which was not observed in inductively coupled oxygen plasma, show that collisional heating is very inefficient in terms of the oxygen capacitive discharge. It appears that this inefficient collisional heating seems to be attributed to a low electric field strength at the center of the oxygen capacitive plasma.

  20. Experimental and simulation study of capacitively coupled electronegative discharges

    NASA Astrophysics Data System (ADS)

    Derzsi, Aranka

    2016-09-01

    The application of tailored voltage waveforms, generated by using multiple harmonics of a base frequency, for the excitation of capacitive RF discharges has been recently introduced as a new method to control the ion flux and ion energy distribution at the electrodes. In plasma processing of surfaces complex mixtures of electronegative, reactive gases (e.g. CF4, O2) are usually required. Therefore, the question of whether this new approach to control ion properties can be applied efficiently to such systems is of exceptional importance. Here the electron heating and ionization dynamics, the possibilities and limitations of the efficient control of plasma parameters by voltage waveform tailoring in low-pressure capacitively coupled electronegative discharges are presented. The focus is on geometrically symmetric O2 plasmas, which are investigated by PIC/MCC simulations and experimental methods. O2 discharges driven by impulse-type and sawtooth-type voltage waveforms composed of a maximum of four consecutive harmonics are studied. Experimental results on the dc self-bias voltage, as well as the spatiotemporal distribution of the plasma emission are compared with simulation data for a wide range of operating conditions (fundamental driving frequencies of 5 MHz - 15 MHz, at pressures of 50 mTorr - 700 mTorr). Transitions between electron power absorption due to sheath expansion and the drift-ambipolar mode were induced both by changing the number of harmonics or by changing the gas pressure. A good agreement between simulation and experiment is found, which shows that the collision-reaction model for O2 discharges underlying the simulations describes reasonably the complicated chemistry of oxygen plasmas. An investigation of the dependence of the discharge characteristics on the surface destruction coefficient of the O2(a1Δg) singlet metastable molecules revealed the crucial role of these species, which strongly affects the negative ion balance of the plasma.

  1. Spin-Spin Coupling in Asteroidal Binaries

    NASA Astrophysics Data System (ADS)

    Batygin, Konstantin; Morbidelli, Alessandro

    2015-11-01

    Gravitationally bound binaries constitute a substantial fraction of the small body population of the solar system, and characterization of their rotational states is instrumental to understanding their formation and dynamical evolution. Unlike planets, numerous small bodies can maintain a perpetual aspheroidal shape, giving rise to a richer array of non-trivial gravitational dynamics. In this work, we explore the rotational evolution of triaxial satellites that orbit permanently deformed central objects, with specific emphasis on quadrupole-quadrupole interactions. Our analysis shows that in addition to conventional spin-orbit resonances, both prograde and retrograde spin-spin resonances naturally arise for closely orbiting, highly deformed bodies. Application of our results to the illustrative examples of (87) Sylvia and (216) Kleopatra multi-asteroid systems implies capture probabilities slightly below ~10% for leading-order spin-spin resonances. Cumulatively, our results suggest that spin-spin coupling may be consequential for highly elongated, tightly orbiting binary objects.

  2. 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.

  3. Effect of capacitive coupling in a miniature inductively coupled plasma source

    SciTech Connect

    Takao, Yoshinori; Eriguchi, Koji; Ono, Kouichi

    2012-11-01

    Two-dimensional axisymmetric particle-in-cell simulations with a Monte Carlo collision algorithm (PIC-MCC) have been conducted to investigate the effect of capacitive coupling in a miniature inductively coupled plasma source (mICP) by using two models: an inductive model and a hybrid model. The mICP is 3 mm in radius and 6 mm in height with a three-turn planar coil, where argon plasma is sustained. In the inductive model, the coil is assumed to be electrostatically shielded, and thus the discharge is purely inductive coupling. In the hybrid model, we assume that the different turns of the coil act like electrodes in capacitive discharge to include the effect of capacitive coupling. The voltage applied to these electrodes decreases linearly from the powered end of the coil towards the grounded end. The numerical analysis has been performed for rf frequencies in the range of 100-1000 MHz, and the power absorbed by the plasma in the range of 5-50 mW at a fixed pressure of 500 mTorr. The PIC-MCC results show that potential oscillations at the plasma-dielectric interface are not negligible, and thus the major component of the absorbed power is caused by the axial motion of electrons in the hybrid model, although almost all of the power absorption is due to the azimuthal motion of electrons in the inductive model. The effect of capacitive coupling is more significant at lower rf frequencies and at higher absorbed powers under the calculation conditions examined. Moreover, much less coil currents are required in the hybrid model.

  4. Electrical characteristics for capacitively coupled radio frequency discharges of helium and neon

    NASA Astrophysics Data System (ADS)

    Tanişli, Murat; Şahin, Neslihan; Demir, Süleyman

    2017-09-01

    In this study, a symmetric radio frequency (RF) (13.56 MHz) electrode discharge system of simple geometry has been designed and made. The electrical properties of capacitive RF discharge of pure neon and pure helium have been obtained from current and voltage waveforms using different reactor designs. Calculations are done, in detail, according to the homogeneous discharge model of capacitively coupled RF. Electrical properties of bulk plasma and sheath capacitance are also investigated at low pressure using this model.

  5. Three-dimensional model of magnetized capacitively coupled plasmas

    NASA Astrophysics Data System (ADS)

    Rauf, Shahid; Kenney, Jason; Collins, Ken

    2009-05-01

    A three-dimensional plasma model is used to understand the characteristics of magnetized capacitively coupled plasma discharges. The simulations consider plasmas generated using high frequency (13.5 MHz) and very high frequency (162 MHz) sources, electropositive (Ar) and electronegative (O2) gases, and spatially uniform and nonuniform magnetic fields. Application of a magnetic field parallel to the electrodes is found to enhance the plasma density due to improved electron confinement and shift the plasma due to the E ×B drift. The plasma is electrically symmetric at 162 MHz so it drifts in opposite directions adjacent to the two electrodes due to the E ×B drift. On the other hand, the 13.5 MHz plasma is electrically asymmetric and it predominantly moves in one direction under the influence of the E ×B drift. The E ×B drift focuses the plasma into a smaller volume in regions with convex magnetic field lines. Conversely, the E ×B drift spreads out the plasma in regions with concave magnetic field lines. In a magnetized O2 plasma, the overall plasma is found to move in one direction due to the E ×B drift while the plasma interior moves in the opposite direction. This behavior is linked to the propensity of negative ions to reside in regions of peak plasma potential, which moves closer to the chamber center opposite to the E ×B drift direction.

  6. Simulation of Dual-Electrode Capacitively Coupled Plasma Discharges

    NASA Astrophysics Data System (ADS)

    Lu, Yijia; Ji, Linhong; Cheng, Jia

    2016-12-01

    Dual-electrode capacitively coupled plasma discharges are investigated here to lower the non-uniformity of plasma density. The dual-electrode structure proposed by Jung splits the electrode region and increases the flexibility of fine tuning non-uniformity. Different RF voltages, frequencies, phase-shifts and electrode areas are simulated and the influences are discussed. RF voltage and electrode area have a non-monotonic effect on non-uniformity, while frequency has a monotonic effect. Phase-shift has a cyclical influence on non-uniformity. A special combination of 224 V voltage and 11% area ratio with 10 MHz lowers the non-uniformity of the original set (200 V voltage and 0% area ratio with 10 MHz) by 46.5%. The position of the plasma density peak at the probe line has been tracked and properly tuning the phase-shift can obtain the same trace as tuning frequency or voltage. supported by National Natural Science Foundation of China (No. 51405261)

  7. Characterization of high-pressure capacitively coupled hydrogen plasmas

    SciTech Connect

    Nunomura, S.; Kondo, M.

    2007-11-01

    Capacitively coupled very-high-frequency hydrogen plasmas have been systematically diagnosed in a wide range of a gas pressure from 5 mTorr to 10 Torr. The plasma parameters, ion species, and ion energy distributions (IEDs) are measured using a Langmuir probe, optical emission spectroscopy, and energy filtered mass spectrometer. The measurement results show that the ion species in a hydrogen plasma is determined from ionization channels and subsequent ion-molecule reactions. The ions are dominated by H{sub 2}{sup +} at a less-collisional condition of < or approx. 20 mTorr, whereas those are dominated by H{sub 3}{sup +} at a collisional condition of > or approx. 20 mTorr. The IED is determined by both the sheath potential drop and ion-neutral collisions in the plasma sheath. The IED is broadened for a collisional sheath at > or approx. 0.3 Torr and the ion bombardment energy is lowered. For high-pressure discharge operated at {approx_equal}10 Torr, plasmas are characterized by a low electron temperature of {approx_equal}0.8 eV and a low ion bombardment energy of < or approx. 15 eV.

  8. Extraction of negative ions from pulsed electronegative capacitively coupled plasmas

    SciTech Connect

    Agarwal, Ankur; Rauf, Shahid; Collins, Ken

    2012-08-01

    Charge buildup during plasma etching of dielectric features can lead to undesirable effects, such as notching, bowing, and twisting. Pulsed plasmas have been suggested as a method to achieve charge-free plasma etching. In particular, electronegative plasmas are attractive as the collapse of the plasma potential during the after-glow period of pulsed capacitively coupled plasmas (CCPs) can allow for extraction of negative ions into the feature. The extraction of negative ions in the after-glow of pulsed CCPs sustained in CF{sub 4} containing gas mixtures is computationally investigated. In this paper, the consequences of pulse frequency and gas chemistry on negative ion flux to the wafer are discussed. A low negative ion flux to the wafer was observed only in the late after-glow period of low pulse frequencies. The negative ion flux was found to significantly increase with the addition of highly electronegative gases (such as thermally attaching Cl{sub 2}) even at a high pulse frequency of 10 kHz. As the production of negative ions during the after-glow diminishes, alternative strategies to enhance the flux were also pursued. The flux of negative ions was found to increase by the addition of a pulsed dc voltage on the top electrode that is 180 Degree-Sign out-of-phase with the rf pulse.

  9. Three-dimensional model of magnetized capacitively coupled plasmas

    SciTech Connect

    Rauf, Shahid; Kenney, Jason; Collins, Ken

    2009-05-15

    A three-dimensional plasma model is used to understand the characteristics of magnetized capacitively coupled plasma discharges. The simulations consider plasmas generated using high frequency (13.5 MHz) and very high frequency (162 MHz) sources, electropositive (Ar) and electronegative (O{sub 2}) gases, and spatially uniform and nonuniform magnetic fields. Application of a magnetic field parallel to the electrodes is found to enhance the plasma density due to improved electron confinement and shift the plasma due to the ExB drift. The plasma is electrically symmetric at 162 MHz so it drifts in opposite directions adjacent to the two electrodes due to the ExB drift. On the other hand, the 13.5 MHz plasma is electrically asymmetric and it predominantly moves in one direction under the influence of the ExB drift. The ExB drift focuses the plasma into a smaller volume in regions with convex magnetic field lines. Conversely, the ExB drift spreads out the plasma in regions with concave magnetic field lines. In a magnetized O{sub 2} plasma, the overall plasma is found to move in one direction due to the ExB drift while the plasma interior moves in the opposite direction. This behavior is linked to the propensity of negative ions to reside in regions of peak plasma potential, which moves closer to the chamber center opposite to the ExB drift direction.

  10. Electron and ion kinetics in magnetized capacitively coupled plasma source

    SciTech Connect

    Lee, S. H.; You, S. J.; Chang, H. Y.; Lee, J. K.

    2007-05-15

    One-dimensional particle-in-cell Monte Carlo collision simulations of magnetized argon plasmas in an asymmetric capacitively coupled plasma reactor are presented. At low pressure (10 mTorr), electron kinetics are strongly affected by the magnetic field and transitions from nonlocal to local kinetic property occur with increasing magnetic field which are reflected in spatially resolved calculations of the electron-energy probability function. For high-energy electrons, the transition takes place when the energy-relaxation length is smaller than the system length. For low-energy electrons, however, the transition occurs when the electron-diffusion time scale in the energy space is shorter than the spatial-diffusion time scale in coordinate space. These observations are in agreement with experimental data and theoretical calculations deduced from the Boltzmann equation. The ion energy distribution function (IEDF) on the driven electrode changes from the ion-neutral collisional type to the ion-neutral collisionless type with increasing magnetic field strength. The maximum ion energy in the IEDF decreases and the angular spread in the ion angle distribution function slightly increases with increasing magnetic field strength. These changes are explained in terms of the ratio of the ion-transit time to rf frequency, the sheath length, and the mean potential difference between the driven electrode and the plasma. At high pressure (218 mTorr), electron-neutral collisions disrupt electron gyromotion so that the effects of the magnetic field on electron and ion kinetics are greatly reduced.

  11. Frequency coupling in dual frequency capacitively coupled radio-frequency plasmas

    SciTech Connect

    Gans, T.; Schulze, J.; O'Connell, D.; Czarnetzki, U.; Faulkner, R.; Ellingboe, A. R.; Turner, M. M.

    2006-12-25

    An industrial, confined, dual frequency, capacitively coupled, radio-frequency plasma etch reactor (Exelan registered , Lam Research) has been modified for spatially resolved optical measurements. Space and phase resolved optical emission spectroscopy yields insight into the dynamics of the discharge. A strong coupling of the two frequencies is observed in the emission profiles. Consequently, the ionization dynamics, probed through excitation, is determined by both frequencies. The control of plasma density by the high frequency is, therefore, also influenced by the low frequency. Hence, separate control of plasma density and ion energy is rather complex.

  12. 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.

  13. Capacitive coupling reduces instrumentation-related infection in rabbit spines: a pilot study.

    PubMed

    Gilotra, Mohit; Griffith, Cullen; Schiavone, Jason; Nimmagadda, Naren; Noveau, Jenna; Ludwig, Steven C

    2012-06-01

    Postoperative spine infections cause considerable morbidity. Patients are subjected to long-term antibiotic regimens and may require further surgery. Delivery of electric current through instrumentation can detach biofilm, allowing better antibiotic penetration and assisting in eradicating infection. We asked (1) whether capacitive coupling treatment in combination with a single dose of antibiotics would reduce infection rates when compared with antibiotics alone in a rabbit spine infection model, (2) whether it would decrease the overall bacterial burden, and (3) whether there was a time-dependent response based on days treated with capacitive coupling. Thirty rabbits were subjected to a well-established spine infection model with a single dose of intravenously administered systemic ceftriaxone (20 mg/kg of body weight) prophylaxis. Two noncontiguous rods were implanted inside dead space defects at L3 and L6 challenged with 10(6) colony-forming units of Staphylococcus aureus. Rabbits were randomly treated with a capacitive coupling or control device. Instrumentation and soft tissue bacterial growth were assessed after 7 days. Sites treated with capacitive coupling showed a decrease in the incidence of positive culture: 36% versus 81% in the control group. We observed no difference in the soft tissue's infectious burden. Overall bacterial load was not decreased with capacitive coupling. Capacitive coupling in conjunction with antibiotics reduced the instrumentation-related infection rate compared with antibiotics alone. Capacitive coupling noninvasively delivers an alternating current that may detach biofilm from instrumentation. Treatment of infection may be successful without removal of instrumentation, allowing for improved stability and overall decreased morbidity.

  14. 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.

  15. Effects of capacitance termination of the internal antenna in inductively coupled plasma

    NASA Astrophysics Data System (ADS)

    Suzuki, K.; Konishi, K.; Nakamura, K.; Sugai, H.

    2000-05-01

    In a conventional inductive rf discharge, the electrostatic coupling from the coil to the plasma causes a serous problem of sputtering of any dielectric materials in the vicinity of the coil. This paper reports the suppression of the electrostatic coupling by terminating the coil (inductance L ) with a capacitor (capacitance C ). The suppression resonantly takes place when the termination reactance (1/icons/Journals/Common/omega" ALT="omega" ALIGN="TOP"/> C ) coincides with a half of the coil reactance (icons/Journals/Common/omega" ALT="omega" ALIGN="TOP"/> L ). In this condition, the plasma density is observed to increase by ~50% at the same input power, in comparison with the conventional internal antenna inductively coupled plasma without the capacitance termination. The electrical transmission-line properties of the coil well account for the termination capacitance dependence of the coil voltages, currents, plasma potential oscillation, plasma density and dc self-bias voltage.

  16. Capacitive coupled RF discharge: modelling at the local and not local statement of the problem

    NASA Astrophysics Data System (ADS)

    Askhatov, R. M.; Chebakova, V. Yu; Zheltukhin, V. S.

    2016-11-01

    The models provided in the research paper describe a capacitive coupled radiofrequency discharge in argon between two parallel plate electrodes, one of which is grounded, and the other is connected to the high-frequency capacitive generator. Herein we review various approaches to simulate a high-frequency capacitive discharge depending on modelled pressure rates. The model of a high-frequency capacitive discharge under low pressure is simulated in non-local approximation, and under high pressure is simulated in local approximation and is sensitive to dimers and molecular ions. We provide calculation data with respect to different pressures and make comparative analysis of data provided by other authors in particular, analysis of data obtained with real experiment.

  17. Proposal for Wireless Power Distribution System with Capacitive Coupling Using One-Pulse Switching Active Capacitor

    NASA Astrophysics Data System (ADS)

    Funato, Hirohito; Chiku, Yuki; Harakawa, Ken-Ichi

    Wireless electric power distribution is an attractive means of supplying power to mobile equipment such as mobile phones and electric vehicles. Magnetic field coupling is the most popular method for wireless power distribution. However, this method has certain disadvantages such as power decrease in the case of inexact placement of couplings. Wireless power distribution with capacitive coupling has been proposed to overcome the disadvantages of wireless power distribution with magnetic field coupling. It is, however, difficult to transfer high power owing to the small capacitance of capacitive coupling. The authors propose a new power converter suitable for wireless power distribution with capacitive coupling using a novel one-pulse switching active capacitor (OPSAC) to enhance power transfer. The proposed system improves the power transfer efficiency without LC resonance and is hence robust to parameter change. In this paper, a wireless power distribution system with improved OPSAC (I-OPSAC) is proposed. In the I-OPSAC, the dc voltage source for the inverter is replaced by a capacitor because the OPSAC behaves like a reactive element. The I-OPSAC shows stable operation without any feedback loop including dc capacitor voltage control. In this paper, a control scheme and the detailed operational characteristics are reported, in addition to the simulations and experimental results.

  18. Effective design of multiple hollow cathode electrode to enhance the density of rf capacitively coupled plasma

    SciTech Connect

    Lee, H. S.; Lee, Y. S.; Seo, S. H.; Chang, H. Y.

    2010-08-23

    Multiple-hole electrode rf capacitively coupled plasma is experimentally studied to determine the optimum condition for high-density plasma discharge. The plasma density was measured at various pressures, hole diameters, rf currents, and gas species conditions. The bulk plasma intrusion in the hole and the ionization avalanche in the sheath region facilitated high-density plasma generation when the diameter of the hole is slightly wider than triple the sheath length. The analytic design of the efficient multihole electrode for high-density rf capacitively coupled plasma discharge will be discussed.

  19. Collisionless bounce resonance heating in dual-frequency capacitively coupled plasmas.

    PubMed

    Liu, Yong-Xin; Zhang, Quan-Zhi; Jiang, Wei; Hou, Lu-Jing; Jiang, Xiang-Zhan; Lu, Wen-Qi; Wang, You-Nian

    2011-07-29

    We present the experimental evidence of the collisionless electron bounce resonance heating (BRH) in low-pressure dual-frequency capacitively coupled plasmas. In capacitively coupled plasmas at low pressures when the discharge frequency and gap satisfy a certain resonant condition, the high energy beamlike electrons can be generated by fast sheath expansion, and heated by the two sheaths coherently, thus the BRH occurs. By using a combined measurement of a floating double probe and optical emission spectroscopy, we demonstrate the effect of BRH on plasma properties, such as plasma density and light emission, especially in dual-frequency discharges.

  20. Effective design of multiple hollow cathode electrode to enhance the density of rf capacitively coupled plasma

    NASA Astrophysics Data System (ADS)

    Lee, H. S.; Lee, Y. S.; Seo, S. H.; Chang, H. Y.

    2010-08-01

    Multiple-hole electrode rf capacitively coupled plasma is experimentally studied to determine the optimum condition for high-density plasma discharge. The plasma density was measured at various pressures, hole diameters, rf currents, and gas species conditions. The bulk plasma intrusion in the hole and the ionization avalanche in the sheath region facilitated high-density plasma generation when the diameter of the hole is slightly wider than triple the sheath length. The analytic design of the efficient multihole electrode for high-density rf capacitively coupled plasma discharge will be discussed.

  1. Low Voltage Low Power Quadrature LC Oscillator Based on Back-gate Superharmonic Capacitive Coupling

    NASA Astrophysics Data System (ADS)

    Ma, Minglin; Li, Zhijun

    2013-09-01

    This work introduces a new low voltage low power superharmonic capacitive coupling quadrature LC oscillator (QLCO) made by coupling two identical cross-connected LC oscillators without tail transistor. In each of the core oscillators, the back-gate nodes of the cross-coupled NMOS pair and PMOS pair, acting as common mode nodes, have been connected directly. Then the core oscillators are coupled together via capacitive coupling of the PMOS common mode node in one of the core oscillators to the NMOS common mode node in the other core oscillator, and vice versa. Only capacitors are used for coupling of the two core oscillators and therefore no extra noise sources are imposed on the circuit. Operation of the proposed QLCO was investigated with simulation using a commercial 0.18 µm RF CMOS technology: it shows a power dissipation of 5.2 mW from a 0.6 V supply voltage. Since the proposed core oscillator has Complementary NMOS and PMOS cross coupled pairs, and capacitive coupling method will not introduce extra phase noise, so this circuit can operate with a low phase noise as low as -126.8 dBc/Hz at 1 MHz offset from center oscillation frequency of 2.4 GHz, as confirmed with simulation.

  2. Electron kinetics in capacitively coupled plasmas modulated by electron injection

    NASA Astrophysics Data System (ADS)

    Zhang, Ya; Peng, Yanli; Innocenti, Maria Elena; Jiang, Wei; Wang, Hong-yu; Lapenta, Giovanni

    2017-09-01

    The controlling effect of an electron injection on the electron energy distribution function (EEDF) and on the energetic electron flux, in a capacitive radio-frequency argon plasma, is studied using a one-dimensional particle-in-cell/Monte Carlo collisions model. The input power of the electron beam is as small as several tens of Watts with laboratory achievable emission currents and energies. With the electron injection, the electron temperature decreases but with a significant high energy tail. The electron density, electron temperature in the sheath, and electron heating rate increase with the increasing emission energy. This is attributed to the extra heating of the energetic electrons in the EEDF tail. The non-equilibrium EEDF is obtained for strong non-local distributions of the electric field, electron heating rate, excitation, and ionization rate, indicating the discharge has transited from a volume heating (α-mode dominated) into a sheath heating (γ-mode dominated) type. In addition, the electron injection not only modifies the self-bias voltage, but also enhances the electron flux that can reach the electrodes. Moreover, the relative population of energetic electrons significantly increases with the electron injection compared to that without the electron injection, relevant for modifying the gas and surface chemistry reactions.

  3. 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.

  4. Characteristic temperatures and electron number densities in an R.F. capacitively coupled plasma.

    PubMed

    Anghel, S D; Frentiu, T; Darvasi, E; Rusu, A M; Simon, A; Cordos, E A

    1996-06-01

    The excitation temperatures of Ar and Fe, the ionization temperatures of Ar and Ca and the electron number densities have been determined for a radiofrequency capacitively coupled plasma in the tip-ring electrode geometry. The temperatures and the electron number densities possess their maximum value close to the electrodes.

  5. Capacitively Coupled Radio Frequency Discharge Plasmas In Hydrogen: Particle Modeling and Negative Ion Kinetics

    SciTech Connect

    Diomede, P.; Longo, S.; Capitelli, M.

    2005-05-16

    We present a 1D(r)2D(v) particle code for capacitively coupled radio frequency discharge plasmas in hydrogen, which includes a rigorous kinetic modeling of ion transport and several solutions to speed up the convergence. In a test case the effect of surface atom recombination and molecule vibrational deactivation on H- concentration is investigated.

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

    DOE PAGES

    Benz, Alexander; Campione, Salvatore; Klem, John Frederick; ...

    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.

  7. 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.

  8. A biosignal instrumentation system using capacitive coupling for power and signal isolation.

    PubMed

    Piipponen, Kari Väinö Tapio; Sepponen, Raimo; Eskelinen, Pekka

    2007-10-01

    Requirements for patient safety and a high interference rejection ratio in medical equipment create a demand for effective isolation devices. A system scale approach that uses capacitive coupling for power and signal isolation is presented. In addition, we describe the development of an instrumentation system prototype that applies microwaves for power exchange and bidirectional data transfer across the isolation barrier. The system consists of an isolated transducer unit, a central unit, and a single coaxial cable between the units. The isolation capacitance is as low as 1.6 pF, inclusive of the digital data transfer and power exchange up to 600 mW of isolated direct current (dc) power. The system is suitable for line-powered biopotential measurements and it is shown that reducing the isolation capacitance from 180 to 1.6 pF improves the power line rejection by 30 dB in a typical electrocardiogram (ECG) measurement setup.

  9. 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.

  10. Electrical Properties for Capacitively Coupled Radio Frequency Discharges of Helium and Neon at Low Pressure

    NASA Astrophysics Data System (ADS)

    Tanisli, Murat; Sahin, Neslihan; Demir, Suleyman

    2016-10-01

    In this study, the symmetric radio frequency (RF) electrode discharge is formed between the two electrodes placing symmetric parallel. The electrical properties of symmetric capacitive RF discharge of pure neon and pure helium have been obtained from current and voltage waveforms. Calculations are done according to the homogeneous discharge model of capacitively coupled radio frequency (CCRF) using with the data in detail. Electrical properties of bulk plasma and sheath capacitance are also investigated at low pressure with this model. This study compares the electrical characteristics and sheath capacitance changes with RF power and pressure for helium and neon discharges. Also, the aim of the study is to see the differences between helium and neon discharges' current and voltage values. Their root-mean-square voltages and currents are obtained from Tektronix 3052C oscilloscope. Modified homogeneous discharge model of CCRF is used for low pressure discharges and the calculations are done using experimental results. It is seen that homogeneous discharge model of CCRF is usable with modification and then helium and neon discharge's electrical properties are investigated and presented with a comparison. Helium discharge's voltage and current characteristic have smaller values than neon's. It may be said that neon discharge is a better conductor than helium discharge. It is seen that the sheath capacitance is inversely correlation with sheath resistance.

  11. A hybrid binary particle swarm optimization for large capacitated multi item multi level lot sizing (CMIMLLS) problem

    NASA Astrophysics Data System (ADS)

    Mishra, S. K.; Sahithi, V. V. D.; Rao, C. S. P.

    2016-09-01

    The lot sizing problem deals with finding optimal order quantities which minimizes the ordering and holding cost of product mix. when multiple items at multiple levels with all capacity restrictions are considered, the lot sizing problem become NP hard. Many heuristics were developed in the past have inevitably failed due to size, computational complexity and time. However the authors were successful in the development of PSO based technique namely iterative improvement binary particles swarm technique to address very large capacitated multi-item multi level lot sizing (CMIMLLS) problem. First binary particle Swarm Optimization algorithm is used to find a solution in a reasonable time and iterative improvement local search mechanism is employed to improvise the solution obtained by BPSO algorithm. This hybrid mechanism of using local search on the global solution is found to improve the quality of solutions with respect to time thus IIBPSO method is found best and show excellent results.

  12. 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.

  13. Electrical asymmetry effects in magnetized capacitively coupled plasmas in argon

    NASA Astrophysics Data System (ADS)

    Yang, Shali; Zhang, Ya; Wang, Hong-Yu; Wang, Shuai; Jiang, Wei

    2017-06-01

    Geometrically symmetric and electrically asymmetric discharges operating at 13.56 MHz and 27.12 MHz with variable phase angle between the harmonics are simulated by a one-dimensional implicit particle-in-cell/Monte Carlo collision model in argon at a pressure of 30 mTorr. The amplitude of each of the harmonics is chosen to be 150 V. The magnetic fields, with strengths of 10 G and 100 G, are parallel to the electrodes and homogeneous throughout the entire electrode gap in a direction perpendicular to the electrodes. It is found that, with a weaker magnetic field at 10 G, the plasma density is nearly doubled and the self-bias is almost unaffected. However, with a stronger magnetic field at 100 G, the plasma density is significantly increased and nearly independent of the phase angle, but at the cost of decreasing the self-bias, which results in a smaller adjustable range of ion bombardment energy. In general, we have demonstrated that an external magnetic field will expand the operational parameter spaces and thus may promote some related applications in coupled plasma sources with electrical asymmetry effects.

  14. 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.

  15. Cu-Zn binary phase diagram and diffusion couples

    NASA Technical Reports Server (NTRS)

    Mccoy, Robert A.

    1992-01-01

    The objectives of this paper are to learn: (1) what information a binary phase diagram can yield; (2) how to construct and heat treat a simple diffusion couple; (3) how to prepare a metallographic sample; (4) how to operate a metallograph; (5) how to correlate phases found in the diffusion couple with phases predicted by the phase diagram; (6) how diffusion couples held at various temperatures could be used to construct a phase diagram; (7) the relation between the thickness of an intermetallic phase layer and the diffusion time; and (8) the effect of one species of atoms diffusing faster than another species in a diffusion couple.

  16. System for unconstrained ECG measurement on a toilet seat using capacitive coupled electrodes : the efficacy and practicality.

    PubMed

    Baek, Hyun Jae; Kim, Jung Soo; Kim, Ko Keun; Park, Kwang Suk

    2008-01-01

    Home healthcare is a common matter of concern to modern people. For the successful home healthcare, unconstrained bio-signal monitoring is important. Previously, unconstrained lavatory typed ECG measurement system was developed. It is enough to measure subject's ECG signal non-intrusively, but not practical because of moist environment of toilet. In this study, capacitive coupled electrode was employed for overcome above disadvantages. ECG was obtained by capacitive coupled electrode and compared with ECGs obtained from conventional Ag/AgCl electrode. Possible motion artifacts were investigated. Experimental results showed that toilet based capacitive coupled ECG signal was measured successfully.

  17. 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.

  18. 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

  19. Effect of the driving frequency on a VHF capacitively coupled plasma

    NASA Astrophysics Data System (ADS)

    Takahashi, Hiroyuki; Yagisawa, Takashi; Makabe, Toshiaki

    2007-10-01

    In the next-generation ULSI process, a capacitively coupled VHF (UHF) plasma will be employed in order to obtain higher plasma density with large size of electrodes (˜ m). Then the system will be subject to the strong electromagnetic effect, such as a standing wave and a skin effect. The effect of the standing wave causes nonuniformity along the radial direction to the capacitively coupled plasma (CCP), when the size of the electrode is comparable to the wavelength of the VHF(UHF) voltage source on the electrode. In the present study, nonuniformity of the potential distribution is numerically investigated on a large electrode in the VHF-CCP in Ar in the cylindrical coordinate system (r, z) by using the combination between the transmission line model (TLM) and the relaxation continuum (RCT) model. The influence of potential nonuniformity on the plasma structure will be discussed in detail.

  20. Capacitively Coupled Arrays of Multiplexed Flexible Silicon Transistors for Long-Term Cardiac Electrophysiology

    PubMed Central

    Fang, Hui; Yu, Ki Jun; Gloschat, Christopher; Yang, Zijian; Chiang, Chia-Han; Zhao, Jianing; Won, Sang Min; Xu, Siyi; Trumpis, Michael; Zhong, Yiding; Song, Enming; Han, Seung Won; Xue, Yeguang; Xu, Dong; Cauwenberghs, Gert; Kay, Matthew; Huang, Yonggang; Viventi, Jonathan; Efimov, Igor R.; Rogers, John A.

    2017-01-01

    Advanced capabilities in electrical recording are essential for the treatment of heart-rhythm diseases. The most advanced technologies use flexible integrated electronics; however, the penetration of biological fluids into the underlying electronics and any ensuing electrochemical reactions pose significant safety risks. Here, we show that an ultrathin, leakage-free, biocompatible dielectric layer can completely seal an underlying layer of flexible electronics while allowing for electrophysiological measurements through capacitive coupling between tissue and the electronics, and thus without the need for direct metal contact. The resulting current-leakage levels and operational lifetimes are, respectively, four orders of magnitude smaller and between two and three orders of magnitude longer than those of any other flexible-electronics technology. Systematic electrophysiological studies with normal, paced and arrhythmic conditions in Langendorff hearts highlight the capabilities of the capacitive-coupling approach. Our technology provides a realistic pathway towards the broad applicability of biocompatible, flexible electronic implants. PMID:28804678

  1. Error-reducing sequence for capacitively coupled singlet-triplet qubits

    NASA Astrophysics Data System (ADS)

    Calderon-Vargas, Fernando; Kestner, Jason

    Two-qubit gates can be implemented by capacitively coupling singlet-triplet qubits, which has been experimentally demonstrated to be capable of generating entangling operations. However, the fidelity of the entangling two-qubit gates is still far from optimum. In this light, we propose a two-qubit entangling echo sequence that reduces drastically the two-qubit decoherence due to the Overhauser field fluctuation and improves the fidelity of two-qubit gates under charge noise.

  2. Determination of mono-, di-, and oligosaccharides by capillary electrophoresis with capacitively coupled contactless conductivity detection.

    PubMed

    do Lago, Claudimir Lucio; Nogueira, Thiago; Blanes, Lucas; Saito, Renata Mayumi

    2013-01-01

    Saccharides and chitooligosaccharides can be separated in electrophoretic conditions by raising the pH of the medium, which renders the corresponding alcoholate forms. These anionic species can be separated and detected with capacitively coupled contactless conductivity detection as negative peaks because of their low mobilities when compared to the hydroxyl mobility, which is the main co-ion in the background electrolyte. Three methods for different matrixes are presented in this chapter.

  3. Capacitively coupled electric field for pain relief in patients with vertebral fractures and chronic pain.

    PubMed

    Rossini, Maurizio; Viapiana, Ombretta; Gatti, Davide; de Terlizzi, Francesca; Adami, Silvano

    2010-03-01

    Fragility vertebral fractures often are associated with chronic back pain controlled by analgesic compounds. Capacitive coupling electrical stimulation is a type of electrical stimulation technology approved by the US FDA to noninvasively enhance fracture repair and spinal fusion. These uses suggest it would be a possible treatment for patients with back pain attributable to vertebral fractures. We therefore randomized 51 postmenopausal women with multiple fractures and chronic pain to the use of one of two indistinguishable devices delivering either the standard capacitive coupling electrical stimulation by Osteospine (active group) or low intensity pulse (control group). Twenty patients of the active group and 21 of the control group (80%) completed the study for a total duration of 3 months. The mean visual analog scale values for pain and the Quality of Life Questionnaire of the European Foundation for Osteoporosis (QUALEFFO) scores improved in both groups. We observed a relationship between hours of treatments and reductions in pain intensity only in the active group. Capacitive coupling electrical stimulation was not more effective than control treatment when comparing mean visual analog scale pain and QALEFFO scores in the two groups and when adjusting for the hours of treatment. However, the proportion of patients able to discontinue NSAIDs owing to elimination or reduction of pain was greater in the active group than in the control group. We interpret these findings as suggesting capacitive coupling electrical stimulation controls pain in some patients and reduces the use of NSAIDs. Level I, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence.

  4. Diagnostics of ballistic electrons in a dc/rf hybrid capacitively coupled discharge

    NASA Astrophysics Data System (ADS)

    Xu, Lin; Chen, Lee; Funk, Merritt; Ranjan, Alok; Hummel, Mike; Bravenec, Ron; Sundararajan, Radha; Economou, Demetre J.; Donnelly, Vincent M.

    2008-12-01

    The energy distribution of ballistic electrons in a dc/rf hybrid parallel-plate capacitively coupled plasma reactor was measured. Ballistic electrons originated as secondaries produced by ion and electron bombardment of the electrodes. The energy distribution of ballistic electrons peaked at the value of the negative bias applied to the dc electrode. As that bias became more negative, the ballistic electron current on the rf substrate electrode increased dramatically. The ion current on the dc electrode also increased.

  5. Solution of the problem of interaction between capacitive coupled radio-frequency discharge and a sample

    NASA Astrophysics Data System (ADS)

    Chebakova, V. Ju; Gaisin, A. F.; Zheltukhin, V. S.

    2016-11-01

    The numerical study of interaction between the capacitive coupled radio frequency (CCRF) discharge and materials is performed. A nonlinear problem, which includes initialboundary value problems for electron, ion, neutral atom, metastable atom, gas temperature and Poisson's equation is solved. A harmonic voltage on the loaded electrodes and Ohm's law for the sample is assumed. A results of calculations of the model problem at pressure p=760 Torr, frequency of generator f=13.76 MHz in local approximation are presented.

  6. Diagnostics of ballistic electrons in a dc/rf hybrid capacitively coupled discharge

    SciTech Connect

    Xu Lin; Chen, Lee; Funk, Merritt; Ranjan, Alok; Hummel, Mike; Bravenec, Ron; Sundararajan, Radha; Economou, Demetre J.; Donnelly, Vincent M.

    2008-12-29

    The energy distribution of ballistic electrons in a dc/rf hybrid parallel-plate capacitively coupled plasma reactor was measured. Ballistic electrons originated as secondaries produced by ion and electron bombardment of the electrodes. The energy distribution of ballistic electrons peaked at the value of the negative bias applied to the dc electrode. As that bias became more negative, the ballistic electron current on the rf substrate electrode increased dramatically. The ion current on the dc electrode also increased.

  7. Capacitively Coupled Electric Field for Pain Relief in Patients with Vertebral Fractures and Chronic Pain

    PubMed Central

    Viapiana, Ombretta; Gatti, Davide; de Terlizzi, Francesca; Adami, Silvano

    2009-01-01

    Fragility vertebral fractures often are associated with chronic back pain controlled by analgesic compounds. Capacitive coupling electrical stimulation is a type of electrical stimulation technology approved by the US FDA to noninvasively enhance fracture repair and spinal fusion. These uses suggest it would be a possible treatment for patients with back pain attributable to vertebral fractures. We therefore randomized 51 postmenopausal women with multiple fractures and chronic pain to the use of one of two indistinguishable devices delivering either the standard capacitive coupling electrical stimulation by Osteospine™ (active group) or low intensity pulse (control group). Twenty patients of the active group and 21 of the control group (80%) completed the study for a total duration of 3 months. The mean visual analog scale values for pain and the Quality of Life Questionnaire of the European Foundation for Osteoporosis (QUALEFFO) scores improved in both groups. We observed a relationship between hours of treatments and reductions in pain intensity only in the active group. Capacitive coupling electrical stimulation was not more effective than control treatment when comparing mean visual analog scale pain and QALEFFO scores in the two groups and when adjusting for the hours of treatment. However, the proportion of patients able to discontinue NSAIDs owing to elimination or reduction of pain was greater in the active group than in the control group. We interpret these findings as suggesting capacitive coupling electrical stimulation controls pain in some patients and reduces the use of NSAIDs. Level of Evidence: Level I, therapeutic study. See Guidelines for Authors for a complete description of levels of evidence. PMID:19756902

  8. 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.

  9. Nanoparticle growth and transport mechanisms in capacitively coupled silane discharges: a numerical investigation

    SciTech Connect

    Bleecker, K. de; Bogaerts, A.; Goedheer, W.J.

    2005-10-31

    A self-consistent 1D fluid model is used to investigate the formation, growth and transport mechanisms of sub-micrometer particles in a low pressure capacitively coupled radio-frequency silane (SiH4) discharge. In this contribution we analyze the competition between the different forces governing the transport of nanometer-sized particles and the specific role of the thermophoretic force arising from a thermal gradient in gas temperature induced by heating or cooling of the electrodes. Further growth of the nanoparticles due to coagulation is also described by coupling the 1D fluid model with an aerosol dynamics model.

  10. Experimental Characterization of Dual-Frequency Capacitively Coupled Plasma with Inductive Enhancement in Argon

    NASA Astrophysics Data System (ADS)

    Bai, Yang; Jin, Chenggang; Yu, Tao; Wu, Xuemei; Zhuge, Lanjian; Ning, Zhaoyuan; Ye, Chao; Ge, Shuibing

    2013-10-01

    The dual-frequency capacitively coupled plasma (DF-CCP) with inductive enhancement system is a newly designed plasma reactor. Different from the conventional inductively coupled plasma (ICP) reactors, now a radio frequency (rf) power is connected to an antenna placed outside the chamber with a one-turn bare coil placed between two electrodes in DF-CCP. This paper gives a detailed description of its structure. Moreover, investigations on some characteristics of discharges in this apparatus were made via a Langmuir probe.

  11. Measurements of time average series resonance effect in capacitively coupled radio frequency discharge plasma

    SciTech Connect

    Bora, B.; Bhuyan, H.; Favre, M.; Wyndham, E.; Chuaqui, H.; Kakati, M.

    2011-10-15

    Self-excited plasma series resonance is observed in low pressure capacitvely coupled radio frequency discharges as high-frequency oscillations superimposed on the normal radio frequency current. This high-frequency contribution to the radio frequency current is generated by a series resonance between the capacitive sheath and the inductive and resistive bulk plasma. In this report, we present an experimental method to measure the plasma series resonance in a capacitively coupled radio frequency argon plasma by modifying the homogeneous discharge model. The homogeneous discharge model is modified by introducing a correction factor to the plasma resistance. Plasma parameters are also calculated by considering the plasma series resonances effect. Experimental measurements show that the self-excitation of the plasma series resonance, which arises in capacitive discharge due to the nonlinear interaction of plasma bulk and sheath, significantly enhances both the Ohmic and stochastic heating. The experimentally measured total dissipation, which is the sum of the Ohmic and stochastic heating, is found to increase significantly with decreasing pressure.

  12. Electrical description of N2 capacitively coupled plasmas with the global model

    NASA Astrophysics Data System (ADS)

    Cao, Ming-Lu; Lu, Yi-Jia; Cheng, Jia; Ji, Lin-Hong; Engineering Design Team

    2016-10-01

    N2 discharges in a commercial capacitively coupled plasma reactor are modelled by a combination of an equivalent circuit and the global model, for a range of gas pressure at 1 4 Torr. The ohmic and inductive plasma bulk and the capacitive sheath are represented as LCR elements, with electrical characteristics determined by plasma parameters. The electron density and electron temperature are obtained from the global model in which a Maxwellian electron distribution is assumed. Voltages and currents are recorded by a VI probe installed after the match network. Using the measured voltage as an input, the current flowing through the discharge volume is calculated from the electrical model and shows excellent agreement with the measurements. The experimentally verified electrical model provides a simple and accurate description for the relationship between the external electrical parameters and the plasma properties, which can serve as a guideline for process window planning in industrial applications.

  13. Data Mechanics and Coupling Geometry on Binary Bipartite Networks

    PubMed Central

    Fushing, Hsieh; Chen, Chen

    2014-01-01

    We quantify the notion of pattern and formalize the process of pattern discovery under the framework of binary bipartite networks. Patterns of particular focus are interrelated global interactions between clusters on its row and column axes. A binary bipartite network is built into a thermodynamic system embracing all up-and-down spin configurations defined by product-permutations on rows and columns. This system is equipped with its ferromagnetic energy ground state under Ising model potential. Such a ground state, also called a macrostate, is postulated to congregate all patterns of interest embedded within the network data in a multiscale fashion. A new computing paradigm for indirect searching for such a macrostate, called Data Mechanics, is devised by iteratively building a surrogate geometric system with a pair of nearly optimal marginal ultrametrics on row and column spaces. The coupling measure minimizing the Gromov-Wasserstein distance of these two marginal geometries is also seen to be in the vicinity of the macrostate. This resultant coupling geometry reveals multiscale block pattern information that characterizes multiple layers of interacting relationships between clusters on row and on column axes. It is the nonparametric information content of a binary bipartite network. This coupling geometry is then demonstrated to shed new light and bring resolution to interaction issues in community ecology and in gene-content-based phylogenetics. Its implied global inferences are expected to have high potential in many scientific areas. PMID:25170903

  14. Residual Bias Phenomenon in Air-Coupled Ultrasonic Capacitive Film Transducers

    NASA Astrophysics Data System (ADS)

    Holland, Stephen D.; Song, Jun-Ho; Chimenti, D. E.

    2006-03-01

    We discuss in this paper the underlying physics of a residual bias phenomenon, whereby the metalized Mylar films of air-coupled film transducers accept and retain a residual electrostatic charge. Experimental measurements to demonstrate and quantify this effect are reported here, along with a hypothesis of the mechanism of charge transfer and embedding. The measurements show the amplitude performance of the capacitive film transducers as a function of applied bias voltage and frequency. Factors such as humidity and decay time also play roles in the acquisition and holding of charge on a film. We hypothesize that charge transfers from the conductive backplate and collects on the non-metalized side of the film. The charged films therefore are electrostatically attracted to the transducer backplate even with no applied voltage bias. Typically, an externally applied bias voltage is needed to charge the capacitor. With a persistent residual bias effect, these air-coupled capacitive film transducers could be used like conventional piezoelectric transducers with no biasing required. This effect has substantial implications for the operation of air-coupled film transducers.

  15. An Investigation on Ground Electrodes of Capacitive Coupling Human Body Communication.

    PubMed

    Mao, Jingna; Yang, Huazhong; Zhao, Bo

    2017-08-01

    Utilizing the body surface as the signal transmission medium, capacitive coupling human body communication (CC-HBC) can achieve a much higher energy efficiency than conventional wireless communications in future wireless body area network (WBAN) applications. Under the CC-HBC scheme, the body surface serves as the forward signal path, whereas the backward path is formed by the capacitive coupling between the ground electrodes (GEs) of transmitter (TX) and receiver (RX). So the type of communication benefits from a low forward loss, while the backward loss depending on the GE coupling strength dominates the total transmission loss. However, none of the previous works have shown a complete research on the effects of GEs. In this paper, all kinds of GE effects on CC-HBC are investigated by both finite element method (FEM) analysis and human body measurement. We set the TX GE and RX GE at different heights, separation distances, and dimensions to study the corresponding influence on the overall signal transmission path loss. In addition, we also investigate the effects of GEs with different shapes and different TX-to-RX relative angles. Based on all the investigations, an analytical model is derived to evaluate the GE related variations of channel loss in CC-HBC.

  16. Enhanced sheath heating in capacitively coupled discharges due to non-sinusoidal voltage waveforms

    SciTech Connect

    Lafleur, T.; Boswell, R. W.; Booth, J. P.

    2012-05-07

    Through the use of particle-in-cell simulations, we demonstrate that the power deposition in capacitively coupled discharges (in argon) can be increased by replacing sinusoidal waveforms with Gaussian-shaped voltage pulses (with a repetition frequency of 13.56 MHz). By changing the Gaussian pulse width, electron heating can be directly controlled, allowing for an increased plasma density and ion flux for the same gas pressure and geometrical operating conditions. Analysis of the power deposition profiles and electron distribution functions shows that enhanced electron-sheath heating is responsible for the increased power absorption.

  17. The discharge condition to enhance electron density of capacitively coupled plasma with multi-holed electrode

    SciTech Connect

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

    2012-09-15

    The multi-holed electrode that has been reported to enhance the electron density of the capacitively coupled plasma is now being adopted to speed up the processes. However, the discharge condition when the multi-holed electrode enhances the electron density of the discharge at fixed power is not studied. At low pressure, the multi-holed electrode increased the electron density of the plasma at fixed power. However, the multi-holed electrode is experimentally revealed to lower the electron density at high pressure. In this paper, the different roles of the multi-holed electrode are experimentally studied.

  18. Plasma ionization through wave-particle interaction in a capacitively coupled radio-frequency discharge

    SciTech Connect

    O'Connell, D.; Gans, T.; Vender, D.; Czarnetzki, U.; Boswell, R.

    2007-03-15

    Phase resolved optical emission spectroscopy, with high temporal resolution, shows that wave-particle interactions play a fundamental role in sustaining capacitively coupled rf plasmas. The measurements are in excellent agreement with a simple particle-in-cell simulation. Excitation and ionization mechanisms are dominated by beam-like electrons, energized through the advancing and retreating electric fields of the rf sheath. The associated large-amplitude electron waves, driven by a form of two-stream instability, result in power dissipation through electron trapping and phase mixing.

  19. Effect of transport of growing nanoparticles on capacitively coupled rf discharge dynamics.

    PubMed

    Schweigert, I V; Alexandrov, A L; Ariskin, D A; Peeters, F M; Stefanović, I; Kovacević, E; Berndt, J; Winter, J

    2008-08-01

    We present experimental and numerical studies of the properties of a capacitively coupled 13.56MHz discharge in a mixture of Ar and C2H2 with growing nanosize particles. It is found that at the initial stage of the growth, nanoparticles are accumulated near the sheath-plasma boundaries, where the ionization by electrons is maximal. The nanoparticles suppress the ionization due to the absorbing fast electrons and stimulate a quick change of the plasma parameters followed by a transition between different modes of discharge operation. At that moment the peaked distribution of the dust particles transforms into a flat one.

  20. Theoretical investigation of phase-controlled bias effect in capacitively coupled plasma discharges

    SciTech Connect

    Kwon, Deuk-Chul; Yoon, Jung-Sik

    2011-07-15

    We theoretically investigated the effect of phase difference between powered electrodes in capacitively coupled plasma (CCP) discharges. Previous experimental result has shown that the plasma potential could be controlled by using a phase-shift controller in CCP discharges. In this work, based on the previously developed radio frequency sheath models, we developed a circuit model to self-consistently determine the bias voltage from the plasma parameters. Results show that the present theoretical model explains the experimental results quite well and there is an optimum value of the phase difference for which the V{sub dc}/V{sub pp} ratio becomes a minimum.

  1. Self-excited nonlinear plasma series resonance oscillations in geometrically symmetric capacitively coupled radio frequency discharges

    SciTech Connect

    Donko, Z.; Schulze, J.; Czarnetzki, U.; Luggenhoelscher, D.

    2009-03-30

    At low pressures, nonlinear self-excited plasma series resonance (PSR) oscillations are known to drastically enhance electron heating in geometrically asymmetric capacitively coupled radio frequency discharges by nonlinear electron resonance heating (NERH). Here we demonstrate via particle-in-cell simulations that high-frequency PSR oscillations can also be excited in geometrically symmetric discharges if the driving voltage waveform makes the discharge electrically asymmetric. This can be achieved by a dual-frequency (f+2f) excitation, when PSR oscillations and NERH are turned on and off depending on the electrical discharge asymmetry, controlled by the phase difference of the driving frequencies.

  2. The analysis of conductive solid samples by r.f. capacitively coupled plasma at atmospheric pressure.

    PubMed

    Anghel, S D; Frentiu, T; Rusu, A M; Bese, L; Cordos, E A

    1996-06-01

    A radiofrequency capacitively coupled plasma (rf CCP) with tip-ring electrode geometry has been used for the analysis of Al, Co, Cr, Cu, Mn, Mo, Ni, and V in low and medium alloyed steel. The sample is used as one of the electrodes of the plasma torch. The influence of plasma power, argon flow rate and distance between the electrodes on the analytical signals has been studied. The limits of detection are in the range of 0.001 to 0.048%. The dynamic range is three orders of magnitude.

  3. Capacitive coupled RF discharge: modelling at the local statement of the problem

    NASA Astrophysics Data System (ADS)

    Badriev, I. B.; Chebakova, V. Yu; Zheltukhin, V. S.

    2017-01-01

    In this paper a mathematical model of capacitively coupled RF discharge at atmospheric pressure is constructed, a method of numerical realization of the model is developed, and the numerical calculations are carried out. Comparison of the results of the numerical experiments with the data of other authors, in particular, with the experimental data, is demonstrated as well a model adequacy as effectiveness of the numerical method. A results of calculations of the model problem at pressure of 760 Torr, frequency of generator of 13.76 MHz and interelectrode distance of 20mm, in local approximation are presented.

  4. PIC/MCC simulation for magnetized capacitively coupled plasmas driven by combined dc/rf sources

    NASA Astrophysics Data System (ADS)

    Yang, Shali; Zhang, Ya; Jiang, Wei; Wang, Hongyu; Wang, Shuai

    2016-09-01

    Hybrid dc/rf capacitively coupled plasma (CCP) sources have been popular in substrate etching due to their simplicity in the device structure and better plasma property. In this work, the characteristics of magnetized capacitively coupled plasmas driven by combined dc/rf sources are described by a one-dimensional Particle-in-cell/Monte Carlo collision (PIC/MCC) model. The simulation is using a rf source of 13.56MHz in argon and at a low pressure of 50mTorr. The effects of dc voltage and magnetic field on the plasmas are examined for 200-400V and 0-200Gs. It is found that, to some extent, dc voltage will increase the plasma density, but plasma density drops with increasing dc voltage. The magnetic field will enhance the plasma density significantly, due to the magnetic field will increase the electron life time and decrease the loss to the electrodes. In the bulk plasma, electron temperature is increased with the magnetic field but decreased with the dc voltage. The electron temperature in sheath is higher than in bulk plasma, due to stochastic heating in sheath is greater than Ohmic heating in bulk plasma under low gas pressure. National Natural Science Foundation of China (11405067, 11105057, 11305032, 11275039).

  5. A time-dependent model of pulse-driven radio frequency capacitively coupled collisional plasma sheath

    NASA Astrophysics Data System (ADS)

    Rahman, M. T.; Hossain, M. Mofazzal

    2017-01-01

    The time-dependent model of ion motion is used to propose an analytical model for dual frequency (DF) capacitively coupled plasma (CCP) sheath driven by a pulsed source and a radio-frequency source. In this model, the sheath is considered to be collisional. In this model, the time dependent terms of ion fluid equations are ignored, but the electric field, ion motion and ion density remain time dependent. Electron profile is assumed to be step-like. Analytical expressions for electron sheath width and sheath potential have been developed. The calculated sheath width and potential are compared with the dual radio frequency driven time dependent models of capacitively coupled plasma sheath. From the temporal evaluation of sheath motion and potential, it has been found that pulse driven sheath has higher sheath potential and sheath width than that of conventional radio frequency driven DF CCP. Moreover, it is also found that ion energy spread can be reduced using pulsed power. From the temporal investigation of sheath motion and potential, it has been found that the duty cycle of the pulse power significantly affects sheath width and sheath potential.

  6. RF Power Coupling And Plasma Transport Effects In Magnetized Capacitive Discharges

    SciTech Connect

    Ryan, P.M.; Carter, M.D.; Hoffman, D.J.

    2005-09-26

    Static magnetic fields have been used to expand the operational envelope, increase power efficiency, and control processing parameters in capacitively-coupled radio frequency plasma discharges. A simple physical model has been developed to investigate the roles of the plasma dielectric tensor and plasma transport in determining the ion flux spatial profile along a wafer surface over a range of plasma density, neutral pressure and magnetic field strength and orientation. The model has been incorporated into the MORRFIC code and calculations have been made for a capacitively-coupled 300-mm etch tool operating at frequencies greater than 100 MHz. A Lieberman sheath model show effects that can occur when the sheath voltages are made to be consistent with the driven RF fields in the collisional unmagnetized limit; other sheath models will also be considered. A two-dimensional transport model accounts for magnetized cross-field diffusion. Results isolate magnetic field effects that are caused by modification of the plasma dielectric from transport effects that are caused by the reduced electron mobility perpendicular to the magnetic field.

  7. Determination of pharmaceuticals classified as emerging pollutants using capillary electrophoresis with capacitively coupled contactless conductivity detection.

    PubMed

    Quek, Ngee Mien; Law, Wai Siang; Lau, Hiu Fung; Zhao, Jian Hong; Hauser, Peter C; Li, Sam Fong Yau

    2008-09-01

    A study on the simultaneous separation of 13 pharmaceutical products by capillary electrophoresis with capacitively coupled contactless conductivity detection was presented. The parameters of the background electrolyte, such as pH, organic additives as well as types and concentrations of cyclodextrins (CD) were studied. The optimal separation conditions were achieved with a background electrolyte consisting of 9 mM Tris/5 mM lactic acid at pH 8.0, containing 5% n-propanol, 0.025% gamma-CD, 0.075% hydroxyl-beta-CD and 0.15% dimethyl-beta-CD. Limits of detections ranged from 61 to 1676 microg/L (S/N=3) and the relative standard deviations for migration time and peak area were below 2 and 6%, respectively. This demonstrated the potential of the capillary electrophoresis-capacitively coupled contactless conductivity detection method for biomedical and environmental analysis, as shown in the determination of pharmaceuticals identified as emerging pollutants in water samples.

  8. Modeling of hybridized infrared arrays for characterization of interpixel capacitive coupling

    NASA Astrophysics Data System (ADS)

    Donlon, Kevan; Ninkov, Zoran; Baum, Stefi; Cheng, Linpeng

    2017-02-01

    Interpixel capacitance (IPC) is a deterministic electronic coupling resulting in a portion of signal incident on one pixel of a hybridized detector array being measured in adjacent pixels. Data collected by light sensitive HgCdTe arrays that exhibit this coupling typically goes uncorrected or is corrected by treating the coupling as a fixed point spread function. Evidence suggests that this coupling is not uniform across signal and background levels. Subarrays of pixels using design parameters based upon HgCdTe indium hybridized arrays akin to those contained in the James Webb Space Telescope's NIRcam have been modeled from first principles using Lumerical DEVICE Software. This software simultaneously solves Poisson's equation and the drift diffusion equations yielding charge distributions and electric fields. Modeling of this sort generates the local point spread function across a range of detector parameters. This results in predictive characterization of IPC across scene and device parameters that would permit proper photometric correction and signal restoration to the data. Additionally, the ability to visualize potential distributions and couplings as generated by the models yields insight that can be used to minimize IPC coupling in the design of future detectors.

  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.

  10. 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.

  11. Plasma characteristics in inductively and capacitively coupled hybrid source using single RF power

    NASA Astrophysics Data System (ADS)

    Kim, Kwan-Yong; Lee, Moo-Young; Kim, Tae-Woo; Kim, Ju-Ho; Chung, Chin-Wook

    2016-09-01

    Parallel combined inductively coupled plasma (ICP) and capacitively coupled plasma (CCP) using single RF generator was proposed to linear control of the plasma density with RF power. In the case of ICP, linear control of the plasma density is difficult because there is a density jump up due to E to H transition. Although the plasma density of CCP changes linearly with power, the density is lower than that of ICP due to high ion energy loss at the substrate. In our hybrid source, the single RF power generator was connected to electrode and antenna, and the variable capacitor was installed between the antenna and the power generator to control the current flowing through the antenna and the electrode. By adjusting the current ratio between the antenna and the electrode, linear characteristic of plasma density with RF power is achieved.

  12. 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.

  13. Lumped element modeling of air-coupled capacitive micromachined ultrasonic transducers with annular cell geometry.

    PubMed

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

    2017-04-01

    Air-coupled capacitive micromachined ultrasonic transducers (CMUTs) based on annular cell geometry have recently been reported. Finite element analysis and experimental studies have demonstrated their significant improvement in transmit efficiency compared with the conventional circular-cell CMUTs. Extending the previous work, this paper proposed a lumped element model of annular-cell CMUTs. Explicit expressions of the resonance frequency, modal vector, and static displacement of a clamped annular plate under uniform pressure were first derived based on the plate theory and curve fitting method. The lumped model of an annular CMUT cell was then developed by adopting the average displacement as the spatial variable. Using the proposed model, the ratio of average-to-maximum displacement was derived to be 8/15. Experimental and simulation studies on a fabricated annular CMUT cell verified the effectiveness of the lumped model. The proposed model provides an effective and efficient way to analyze and design air-coupled annular-cell CMUTs.

  14. Imaging using air-coupled polymer-membrane capacitive ultrasonic arrays.

    PubMed

    Neild, A; Hutchins, D A; Billson, D R

    2004-04-01

    Polymer-membrane capacitive ultrasonic linear and 2-D arrays have been fabricated for use in air-coupled imaging. By using arrays as receivers, there is a possibility of much faster imaging as the need for physically moving the receiver to scan a sample can be replaced by electronic multiplexing. In order to utilise this, a through-thickness air-coupled image of a composite plate has been made using a 2-D array as a receiver and a comparatively large planar source in air. This was made possible by the use of a chirp drive signal and cross-correlation on the measured waveform. Larger 2-D arrays with an increased number of elements have been simulated using a small scanned single receiver, and excellent imaging potential demonstrated. In addition two array receivers have been used in conjunction with two methods of post-processing, SAFT and ellipse crossing, to locate objects accurately.

  15. Correlation-induced suppression of decoherence in capacitively coupled Cooper-pair boxes

    NASA Astrophysics Data System (ADS)

    Hu, Xuedong; You, J. Q.; Nori, Franco

    2005-03-01

    Charge fluctuations from gate bias and background traps severely limit the performance of a charge qubit in a Cooper-pair box (CPB). Here we discuss an encoding approachootnotetextJ.Q. You, X.Hu, and F. Nori, cond-mat/0407423. to control the decoherence effects of these charge fluctuations using two strongly capacitively coupled CPBs. This coupled-box system has a low-decoherence subspace of two states, for which we calculate the dephasing and relaxation rates using a master equation approach. Our results show that the inter-box Coulomb correlation can significantly suppress decoherence of this two-level system by reducing the strength of the system-environment interaction, making it a promising candidate as a logical qubit, encoded using two CPBs.

  16. 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

  17. Design and standalone characterisation of a capacitively coupled HV-CMOS sensor chip for the CLIC vertex detector

    NASA Astrophysics Data System (ADS)

    Kremastiotis, I.; Ballabriga, R.; Campbell, M.; Dannheim, D.; Fiergolski, A.; Hynds, D.; Kulis, S.; Peric, I.

    2017-09-01

    The concept of capacitive coupling between sensors and readout chips is under study for the vertex detector at the proposed high-energy CLIC electron positron collider. The CLICpix Capacitively Coupled Pixel Detector (C3PD) is an active High-Voltage CMOS sensor, designed to be capacitively coupled to the CLICpix2 readout chip. The chip is implemented in a commercial 180 nm HV-CMOS process and contains a matrix of 128×128 square pixels with 25μm pitch. First prototypes have been produced with a standard resistivity of ~20 Ωcm for the substrate and tested in standalone mode. The results show a rise time of ~20 ns, charge gain of 190 mV/ke‑ and ~40 e‑ RMS noise for a power consumption of 4.8μW/pixel. The main design aspects, as well as standalone measurement results, are presented.

  18. 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.

  19. Numerical simulation of capacitively-coupled, radio-frequency plasma discharges

    NASA Astrophysics Data System (ADS)

    Hammond, Edward Percy, IV

    This research develops a novel, non-dissipative discretization for the drift-diffusion expression of electron flux in capacitively-coupled, radio-frequency plasma discharges. The new discretization is more robust and accurate than commonly used numerical techniques when applied to the solution of the plasma fluid equations. On a relatively coarse grid, the method provides results within a few percent of the grid-converged solution. Low-order upwinding, a common method for discretization of the electron flux; introduces significant robustness. However, on the same coarse grid, the plasma density can differ from the grid-converged result by nearly a factor of two. Another popular discretization of the electron flux is the Scharfetter-Gummel method. Although it is accurate on coarse grids, it is more expensive computationally due to its non-linear nature, and it introduces an additional approximation. It neglects the electron temperature gradient in the flux expression; this can affect the plasma density as much as 20%. A formal method for accelerating the solution towards the periodic, steady-state solution in one and multiple dimensions is also described. Direct integration of the governing equations in time will lead to the harmonic steady-state, but this may require tens or hundreds of thousands of radio-frequency periods when the plasma discharge contains significant neutral species that develop on a time-scale much longer than a radio-frequency period. In contrast, the acceleration scheme can reach the periodic steady-state in a few hundred to a few thousand radio-frequency periods. Previous efforts that used formal acceleration schemes were limited to one dimension. Finally, a fluid model of an argon plasma is developed and compared to experimental data at conditions relevant to low-pressure, capacitively-coupled plasma discharges. The computed results agree reasonably well with the experiments both quantitatively and qualitatively. This model is then used to

  20. Fiber Bragg grating-based temperature sensor for neutral gas in capacitively coupled plasmas

    NASA Astrophysics Data System (ADS)

    Liu, Zigeng; Han, Daoman; Zhang, Xinpu; Liu, Yongxin; Peng, Wei; Wang, Younian

    2016-11-01

    A fiber Bragg grating (FBG) has been utilized in capacitively coupled plasmas (CCP) for thermometry of neutral gas. We studied the effects of high frequency and low frequency power on radial distribution of neutral gas temperature. The result shows that the neutral gas temperature increases with increasing high frequency power. However, the presence of low frequency power will decrease the neutral gas temperature. Particularly, we eliminated the effect of ion bombardment on temperature measurement by studying axial distribution near plasma-sheath boundary. With features of immune to electromagnetic interference, high precision, and spatial resolving power, the FBG is a commendable candidate for CCP or other radio-frequency plasmas thermometry in both laboratory and industry.

  1. Frequency dependence of the electrical asymmetry effect in dual-frequency capacitively coupled discharges

    SciTech Connect

    Lafleur, T.; Booth, J. P.

    2013-04-15

    Using experimental measurements complemented with particle-in-cell (PIC) simulations, we demonstrate a reduction in the electrical asymmetry effect in capacitively coupled discharges for low excitation frequencies (0.8 MHz < f<10 MHz). These results confirm PIC simulation predictions made by [I. Korolov, Z. Donko, U. Czarnetzki, and J. Schulze, J. Phys. D: Appl. Phys. 45, 465205 (2012)], where this effect was investigated for dual-frequency discharges in which the driving frequencies are phase-shifted harmonics. Because the reduction in electrical asymmetry is a sensitive function of the secondary electron emission coefficient, we are able to non-invasively estimate this coefficient as 0.035 for argon ions incident on aluminium electrodes.

  2. 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.

  3. 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.

  4. 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.

  5. 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

  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. 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.

  8. 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.

  9. High-Temperature Annealing by Subatmospheric-Pressure Radio-Frequency Capacitively Coupled Plasma

    NASA Astrophysics Data System (ADS)

    Miyake, Masatoshi; Yokogawa, Ken'etsu

    2012-08-01

    High-temperature annealing was performed by a novel annealing system using subatmospheric-pressure radio-frequency capacitively coupled plasma (SAP-CCP). The heating characteristics and stability of discharge were studied. An electrode temperature of 1900 °C was obtained with a stable and uniform glow-like discharge. Also, the characteristics of annealing were investigated using silicon wafers implanted with boron ions accelerated by 5 kV at doses of 2.0×1015 cm-2. The sheet resistance decreased with increasing annealing temperature in the same manner as in conventional rapid thermal annealing. As a result, a sheet resistance of 86 Ω/sq was successfully achieved at an electrode temperature of 1080 °C without any surface roughness.

  10. Performance of human body communication-based wearable ECG with capacitive coupling electrodes.

    PubMed

    Sakuma, Jun; Anzai, Daisuke; Wang, Jianqing

    2016-09-01

    Wearable electrocardiogram (ECG) is attracting much attention in daily healthcare applications, and human body communication (HBC) technology provides an evident advantage in making the sensing electrodes of ECG also working for transmission through the human body. In view of actual usage in daily life, however, non-contact electrodes to the human body are desirable. In this Letter, the authors discussed the ECG circuit structure in the HBC-based wearable ECG for removing the common mode noise when employing non-contact capacitive coupling electrodes. Through the comparison of experimental results, they have shown that the authors' proposed circuit structure with the third electrode directly connected to signal ground can provide an effect on common mode noise reduction similar to the usual drive-right-leg circuit, and a sufficiently good acquisition performance of ECG signals.

  11. 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.

  12. Fluid simulation for influence of metastable atoms on the characteristics of capacitively coupled argon plasmas

    SciTech Connect

    Zhang Yuru; Xu Xiang; Wang Younian

    2010-03-15

    One-dimensional self-consistent fluid model is used to simulate the capacitively coupled argon plasma, in which the metastable effect on the plasma parameters at different discharge conditions is investigated. The results show that due to the metastable atom existence, the bulk plasma density drops significantly, especially at high pressures, high voltages, and high frequencies, accompanied by the decrease in electron temperature in the bulk. When the pressure and voltage are high, the metastable atom density is characterized by a saddle distribution in the axis direction. However, with the decrease in voltage and pressure, the metastable atom density becomes a parabolic distribution. Besides, the curve of plasma density with frequency has a minimum, and so is the profile of metastable atom density.

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

    PubMed

    Liu, Xiang-Mei; Song, Yuan-Hong; Xu, Xiang; Wang, You-Nian

    2010-01-01

    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.

  14. 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.

  15. Particle-In-Cell simulation of laser photodetachment in capacitively coupled radio frequency oxygen discharges

    SciTech Connect

    Teichmann, T.; Matyash, K.; Schneider, R.; Küllig, C.; Dittmann, K.; Meichsner, J.

    2013-11-15

    Particle-In-Cell simulations with Monte Carlo collision of capacitively coupled radio frequency oxygen discharges are used to study the appearance and characteristics of two experimentally observed electronegative modes, the high electronegative mode for low peak-to-peak voltage, and the low electronegative mode for high peak-to-peak voltage. For the high electronegative mode, the simulated laser photodetachment signal agrees very well with the experiment. The simulation identifies the dominant transport processes for high electronegativities: electrons flow fast out of the perturbed region, where the laser pulse generates laser detachment of negative ions. Negative ions are not streaming inward, but are produced within this region by dissociative attachment after the laser pulse.

  16. Impact of phase lag on uniformity in pulsed capacitively coupled plasmas

    SciTech Connect

    Agarwal, Ankur; Rauf, Shahid; Collins, Ken

    2011-07-11

    Process uniformity of macro-scale parameters such as electron and ion densities is critical during any plasma process. Pulsed operation of multiple frequency capacitively coupled plasmas (CCPs) has been shown to improve profile characteristics of features during plasma etching. In this work, we consider pulsing of both power sources in a dual frequency CCP. The impact of phase lag between the high frequency and low frequency power pulses on plasma uniformity is examined using a two-dimensional computational plasma model. Results for Ar/CF{sub 4} gas mixture indicate that phase lag allows one to control plasma uniformity by modulating the time for which the high or low frequency source is on.

  17. Analytical characterisation of a capacitively coupled plasma torch with a central tube electrode.

    PubMed

    Cordos, E A; Frentiu, T; Rusu, A M; Angel, S D; Fodor, A; Ponta, M

    1999-04-01

    A new type of radiofrequency capacitively coupled plasma torch is presented. The torch electrode geometry is coaxial with a tubular central electrode and one or two outer ring electrodes. The argon plasma is generated at 275 W radiofrequency power and 27.12 MHz and it has a very good stability and a low gas consumption of 0.4 l min(-1). The nebulized sample is introduced through the tubular electrode into the core of the annular shaped plasma thus achieving a better atomisation and a lower background. The limits of detection for 20 elements are in the range of ng ml(-1) and the dynamic range between 2.5 and 3.5. The best results are obtained with the torch with two outer ring electrodes.

  18. Diagnostics for low-energy electrons in a two-frequency capacitively coupled plasma in Ar

    SciTech Connect

    Ishimaru, M.; Ohba, T.; Ohmori, T.; Yagisawa, T.; Kitajima, T.; Makabe, T.

    2008-02-18

    An experimental procedure to investigate the spatiotemporal characteristics of electrons in the vicinity of mean energy in a radiofrequency plasma is proposed by using optical emission and absorption spectroscopy in Ar. The method employs optical kinetics of long-lived metastable atom Ar(1s{sub 5}) and short-lived excited Ar(2p{sub 9}). The electron density distribution n{sub e}(z,t) is demonstrated in a typical condition in a two-frequency capacitively coupled plasma, excited at 100 MHz and biased at 500 kHz in pure Ar. The density shows almost time independent characteristics in the bulk plasma and a strong time dependence in the sheath in front of the bias electrode.

  19. 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.

  20. Abnormal Heating of Low-Energy Electrons in Low-Pressure Capacitively Coupled Discharges

    SciTech Connect

    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.

  1. Capacitively coupled microwave plasma atomic emission spectrometer for the determination of lead in whole blood.

    PubMed

    Wensing, M W; Smith, B W; Winefordner, J D

    1994-02-15

    The determination of lead in whole blood by atomic emission spectrometry using a capacitively coupled microwave plasma and a tungsten filament electrode is presented. When the plasma-supporting electrode is also used as the sample holder, transfer of the sample to the plasma is 100%. Microwaves are used to dry the sample and, at higher powers, ignite a helium plasma which results in the atomization and excitation of Pb. Using this methodology, a detection limit of 3 pg of Pb was obtained using 5-microL aqueous samples. The precision was 9%. Whole blood samples were subjected to a drying stage similar to that of the aqueous samples. Following this drying stage, a low-power (30 W) helium plasma was ignited and used to ash the blood sample. Higher power plasmas (> 150 W) were used to atomize and excite the Pb. Recovery of Pb from the blood samples was 88%, when compared to aqueous standards.

  2. 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.

  3. Heating of a dual frequency capacitively coupled plasma via the plasma series resonance

    NASA Astrophysics Data System (ADS)

    Semmler, E.; Awakowicz, P.; von Keudell, A.

    2007-11-01

    The behavior of dual frequency capacitively coupled plasma discharges (2f-CCP) is experimentally studied by Langmuir probe and rf current measurements and is compared with simulations from the literature. The driving frequency ratio, system pressure, high frequency (HF) power and low frequency (LF) power are varied in the experiments. An increase in LF power causes a moderate increase in electron density but a significant decrease in electron temperature. An increase in HF power causes a strong increase in electron density and populates the high energy part of the electron energy distribution function. These dependences can be explained on the basis of a global model. It is shown that the ratios of HF/LF power and driving frequency are the most important parameters. At integer frequency ratios a significant increase in electron density was found, which is explained by the indirect heating at the plasma series resonance. Several design guidelines are derived which address industrial applications and process stability.

  4. Broadband microwave absorption and standing wave effect in helium capacitively coupled plasma

    NASA Astrophysics Data System (ADS)

    Zhang, Yachun; He, Xiang; Chen, Jianping; Chen, Li; Zhang, Hongchao; Ni, Xiaowu; Lu, Jian; Shen, Zhonghua

    2017-08-01

    The broadband microwave absorption of a large volume helium plasma, which is generated by two parallel rectangular plates based on the principle of capacitively coupled plasma (CCP) is developed in this paper. The transmission attenuation is simulated by the combination of the time-dependent fluid model and dispersion equation, and measured by a high dynamic range measurement system in a frequency range of 1 -12 GHz . The results show that the plasma can absorb microwave energy efficiently, especially in the frequency range of 1 -5 GHz , where the transmission attenuation is more than -5 dB . The attenuation increases with gas pressures and applied voltages. Besides, the standing wave effect in plasma can increase the microwave absorption effectively. The numerical and experimental results have a qualitative agreement, and these characteristics suggest that the helium CCP has tremendous potential to be applied in plasma stealth.

  5. 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.

  6. Ion flux asymmetry in radiofrequency capacitively-coupled plasmas excited by sawtooth-like waveforms

    NASA Astrophysics Data System (ADS)

    Bruneau, B.; Novikova, T.; Lafleur, T.; Booth, J. P.; Johnson, E. V.

    2014-12-01

    Using particle-in-cell simulations, we predict that it is possible to obtain a significant difference between the ion flux to the powered electrode and that to the grounded electrode—with about 50% higher ion flux on one electrode—in a geometrically symmetric, radiofrequency capacitively-coupled plasma reactor by applying a non-sinusoidal, ‘Tailored’ voltage waveform. This sawtooth-like waveform presents different rising and falling slopes over one cycle. We show that this effect is due to differing plasma sheath motion in front of each electrode, which induces a higher ionization rate in front of the electrode which has the fastest positive rising voltage. Together with the higher ion flux comes a lower voltage drop across the sheath, and therefore a reduced maximum ion bombardment energy; a result in contrast to typical process control mechanisms.

  7. Trielectrode capacitive pressure transducer

    NASA Technical Reports Server (NTRS)

    Coon, G. W. (Inventor)

    1976-01-01

    A capacitive transducer and circuit especially suited for making measurements in a high-temperature environment are described. The transducer includes two capacitive electrodes and a shield electrode. As the temperature of the transducer rises, the resistance of the insulation between the capacitive electrode decreases and a resistive current attempts to interfere with the capacitive current between the capacitive electrodes. The shield electrode and the circuit coupled there reduce the resistive current in the transducer. A bridge-type circuit coupled to the transducer ignores the resistive current and measures only the capacitive current flowing between the capacitive electrodes.

  8. 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.

  9. Experimental study of a very high frequency, 162 MHz, segmented electrode, capacitively coupled plasma discharge

    NASA Astrophysics Data System (ADS)

    Sirse, Nishant; Harvey, Cleo; Gaman, Cezar; Ellingboe, Bert

    2016-09-01

    Radio-frequency capacitively coupled plasma (CCP) discharge operating at a very high frequency, 30-300 MHz, offers many advantages over standard 13.56 MHz CCP. However, there is a limited flexibility on the choice of driving frequency and substrate size due to plasma non-uniformity caused by the standing wave effect and edge effect. To overcome this issue segmented electrode CCP's are proposed and researched. Despite its numerous advantages the power coupling mechanism and plasma chemistry in this type of discharge are not fully understood due to lack of experimental data. In this paper, we present the experimental study of a segmented electrode, 3x4 tile array (10x10 cm square tile with 1 cm tile-to-tile separation), CCP discharge driven at 162 MHz. We measured plasma uniformity and gas temperature using hairpin probe and optical emission spectroscopy respectively. A homemade RF compensated Langmuir probe is employed to measure the Electron Energy Distribution Function (EEDF) by second harmonic technique. Energy resolved quadrupole mass spectrometer is utilized to measure the ion energy distribution. Discharge/plasma properties are investigated for several operating conditions and for power coupling mode in both washer board and checker board configuration. The experimental results show that the uniform plasma density can be maintained over a large area along with highly non-equilibrium condition to produce unique gas phase plasma chemistry.

  10. 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.

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

    SciTech Connect

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

    2007-09-15

    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 (V{sub rf}=50-600 V), frequencies (f=13.56-40.68 MHz), and pressures (p=0.2-1 torr). 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 V{sub rf}, f, or p. The dissociation degree is about 10{sup -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.

  12. 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.

  13. Analytical performance of an r.f. capacitively coupled plasma for atomic emission with tip-ring electrode geometry.

    PubMed

    Frenţiu, T; Rusu, A M; Ponta, M; Anghel, S D; Cordos, E A

    1996-06-01

    A low to medium power radiofrequency capacitively coupled plasma is characterized as spectral source for atomic emission. The signal to background ratio and the limits of detection were determined for 19 elements as a function of the plasma torch geometry and the observation point.

  14. Plasmon coupling in binary metal core-satellite assemblies

    NASA Astrophysics Data System (ADS)

    Sebba, D. S.; Labean, T. H.; Lazarides, A. A.

    2008-10-01

    Controlled plasmon coupling is observed in nanoparticle assemblies composed of 20 nm silver ‘satellite’ nanoparticles tethered by reconfigurable duplex DNA linkers to a 50 nm gold ‘core’ particle. The assemblies incorporate silver nanoparticle-oligonucleotide conjugates prepared using a new conjugation method in which the recognition strand is anchored by a 10 base pair, double strand spacer that presents adjacent 3’- and 5’-thiols to the silver surface. Reconfiguration of the DNA linkers from a compact to an extended state results in decreased core-satellite coupling and a blue-shift in the gold core plasmon resonance. The structural basis for the observed resonance modulation is investigated through simulation of the scattering spectra of binary assemblies with various core-satellite separations. Additional simulations of core-satellite assemblies composed of gold satellite particles bound to silver cores and of assemblies composed entirely of silver particles are used to clarify the dependence of the coupling response on the composition of the components and their distribution within the assembly.

  15. An Energy Efficient Technique Using Electric Active Shielding for Capacitive Coupling Intra-Body Communication.

    PubMed

    Ma, Chao; Huang, Zhonghua; Wang, Zhiqi; Zhou, Linxuan; Li, Yinlin

    2017-09-08

    Capacitive coupling intra-body communication (CC-IBC) has become one of the candidates for healthcare sensor networks due to its positive prevailing features of energy efficiency, transmission rate and security. Under the CC-IBC scheme, some of the electric field emitted from signal (SIG) electrode of the transmitter will couple directly to the ground (GND) electrode, acting equivalently as an internal impedance of the signal source and inducing considerable energy losses. However, none of the previous works have fully studied the problem. In this paper, the underlying theory of such energy loss is investigated and quantitatively evaluated using conventional parameters. Accordingly, a method of electric active shielding is proposed to reduce the displacement current across the SIG-GND electrodes, leading to less power loss. In addition, the variation of such loss in regard to frequency range and positions on human body was also considered. The theory was validated by finite element method simulation and experimental measurement. The prototype result shows that the receiving power has been improved by approximate 5.5 dBm while the total power consumption is maximally 9 mW less using the proposed technique, providing an energy efficient option in physical layer for wearable and implantable healthcare sensor networks.

  16. 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.

  17. Modeling of magnetically enhanced capacitively coupled plasma sources: Two frequency discharges

    SciTech Connect

    Yang Yang; Kushner, Mark J.

    2007-09-15

    Magnetically enhanced, capacitively coupled radio frequency plasma sources are finding continued use for etching of materials for microelectronics fabrication at a time when multifrequency sources are also being developed. Magnetically enhanced reactive ion etching (MERIE) sources typically use magnetic fields of tens to hundreds of Gauss parallel to the substrate to either increase the plasma density at a given pressure or to lower the operating pressure. Multifrequency sources are used to separately control the magnitude of the ion and radical fluxes (typically with a high frequency source) and the ion energy distributions (typically with a low frequency) to the substrate. In this article, the properties of a two-frequency MERIE reactor are discussed using results from a computational investigation. As in single frequency sources, the reduction in transverse electron mobility as the magnetic field increases can produce a reversal of the electric field in the sheath and an increase in voltage drop across the bulk plasma. These trends decrease ion energies and increase the angular spread of ions. Similar trends are found here, including a field reversal in the sheath at the high frequency electrode. These effects produce a coupling between the high and low frequency sources that compromise the independence of ion production and ion acceleration by the two sources.

  18. Capacitively coupled contactless conductivity detection with dual top-bottom cell configuration for microchip electrophoresis.

    PubMed

    Mahabadi, Kambiz A; Rodriguez, Isabel; Lim, Chee Y; Maurya, Devendra K; Hauser, Peter C; de Rooij, Nico F

    2010-03-01

    An optimized capacitively coupled contactless conductivity detector for microchip electophoresis is presented. The detector consists of a pair of top-bottom excitation electrodes and a pair of pickup electrodes disposed onto a very thin plastic microfluidic chip. The detection cell formed by the electrodes is completely encased and shielded in a metal housing. These approaches allow for the enhancement of signal coupling and extraction from the detection cell that result in an improved signal-to-noise-ratio and detection sensitivity. The improved detector performance is illustrated by the electrophoretic separation of six cations (NH(4) (+), K(+), Ca(2+), Na(+), Mg(2+), Li(+)) with a detection limit of approximately 0.3 microM and the analysis of the anions (Br(-), Cl(-), NO(2) (-), NO(3) (-), SO(4) (2-), F(-)) with a detection limit of about 0.15 microM. These LODs are significantly improved compared with previous reports using the conventional top-top electrode geometry. The developed system was applied to the analysis of ions in bottled drinking water samples.

  19. Molecular Dynamics Simulation Study of the Capacitive Performance of a Binary Mixture of Ionic Liquids near an Onion-like Carbon Electrode.

    PubMed

    Li, Song; Feng, Guang; Fulvio, Pasquale F; Hillesheim, Patrick C; Liao, Chen; Dai, Sheng; Cummings, Peter T

    2012-09-06

    An equimolar mixture of 1-methyl-1-propylpyrrolidinium bis(trifluoromethylsulfonyl)imide ([C3mpy][Tf2N]), 1-methyl-1-butylpiperidinium bis(trifluoromethylsulfonyl)imide ([C4mpip][Tf2N]) was investigated by classic molecular dynamics (MD) simulation. Differential scanning calorimetry (DSC) measurements verified that the binary mixture exhibited lower glass transition temperature than either of the pure room-temperature ionic liquids (RTILs). Moreover, the binary mixture gave rise to higher conductivity than the neat RTILs at lower temperature range. In order to study its capacitive performance in supercapacitors, simulations were performed of the mixture, and the neat RTILs used as electrolytes near an onion-like carbon (OLC) electrode at varying temperatures. The differential capacitance exhibited independence of the electrical potential applied for three electrolytes, which is in agreement with previous work on OLC electrodes in a different RTILs. Positive temperature dependence of the differential capacitance was observed, and it was dominated by the electrical double layer (EDL) thickness, which is for the first time substantiated in MD simulation.

  20. Capacitively coupled pickup in MCP-based photodetectors using a conductive metallic anode

    NASA Astrophysics Data System (ADS)

    Angelico, E.; Seiss, T.; Adams, B.; Elagin, A.; Frisch, H.; Spieglan, E.

    2017-02-01

    We have designed and tested a robust 20×20 cm2 thin metal film internal anode capacitively coupled to an external array of signal pads or micro-strips for use in fast microchannel plate photodetectors. The internal anode, in this case a 10 nm-thick NiCr film deposited on a 96% pure Al2O3 3 mm-thick ceramic plate and connected to HV ground, provides the return path for the electron cascade charge. The multi-channel pickup array consists of a printed-circuit card or glass plate with metal signal pickups on one side and the signal ground plane on the other. The pickup can be put in close proximity to the bottom outer surface of the sealed photodetector, with no electrical connections through the photodetector hermetic vacuum package other than a single ground connection to the internal anode. Two pickup patterns were tested using a small commercial MCP-PMT as the signal source: 1) parallel 50 Ω 25-cm-long micro-strips with an analog bandwidth of 1.5 GHz, and 2) a 20×20 cm2 array of 2-dimensional square 'pads' with sides of 1.27 cm or 2.54 cm. The rise-time of the fast input pulse is maintained for both pickup patterns. For the pad pattern, we observe 80% of the directly coupled amplitude. For the strip pattern we measure 34% of the directly coupled amplitude on the central strip of a broadened signal. The physical decoupling of the photodetector from the pickup pattern allows easy customization for different applications while maintaining high analog bandwidth.

  1. 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.

  2. The Capacitance and Electromechanical Coupling of Lipid Membranes Close to Transitions: The Effect of Electrostriction

    PubMed Central

    Heimburg, Thomas

    2012-01-01

    Biomembranes are thin capacitors with the unique feature of displaying phase transitions in a physiologically relevant regime. We investigate the voltage and lateral pressure dependence of their capacitance close to their chain melting transition. Because the gel and the fluid membrane have different area and thickness, the capacitance of the two membrane phases is different. In the presence of external fields, charges exert forces that can influence the state of the membrane, thereby influencing the transition temperature. This phenomenon is called “electrostriction”. We show that this effect allows us to introduce a capacitive susceptibility that assumes a maximum in the melting transition with an associated excess charge. As a consequence, voltage regimes exist in which a small change in voltage can lead to a large uptake of charge and a large capacitive current. Furthermore, we consider electromechanical behavior such as pressure-induced changes in capacitance, and the application of such concepts in biology. PMID:23009841

  3. 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

  4. Investigation of Plasma Uniformity in Pulsed 100 MHz Narrow Gap-Capacitively Coupled Argon Plasma

    NASA Astrophysics Data System (ADS)

    Jang, Yunchang; Choi, Myungsun; Rho, Hyun-Joon; Huh, Sung-Ryul; Yoon, Sung-Young; Ryu, Sangwon; Kim, Gon-Ho

    2015-09-01

    Capacitively coupled plasmas (CCPs) for industrial applications have a narrow gap between two electrodes and a large exhaust region between electrodes and lateral walls. In this study, uniformity of electron density (ne) distribution was investigated in a 300 mm Φ CCP with outer-electrode space 4 times larger than inter-electrode space. The 100 MHz RF power was applied to top electrode at a pulse repetition rate of 5 kHz. Experiments reveals that the non-uniformity of the ne decreases from 0.60 in the active-glow period to 0.39 in after-glow period. In order to account for this phenomenon in the after-glow, the effective diffusion length representing the ratio of plasma generation volume to effective loss area is introduced. When RF power is turned off, the ne of each space starts to decrease with the specific loss rate determined by each leff. The calculated leff of the outer-electrode space is about 3.7 times longer than that in the outer-electrode space. This implies that ne of the outer-electrode space decay more slowly, leading to improve the uniformity. The details on experimental results and analysis will be presented and discussed. This research was supported by BK21 Research Division of Seoul National University for Energy Resources, Ministry of Trade, Industry and Energy Republic of Korea and Consortium of Semiconductor Advanced Research.

  5. Synthesis of highly monodisperse Ge crystals in a capacitively coupled flow through reactor for photovoltaic applications

    NASA Astrophysics Data System (ADS)

    Gresback, Ryan; Kortshagen, Uwe

    2006-10-01

    Germanium nanocrystals are interesting candidates for quantum dot-based solar cells. While the band gap of bulk Ge is ˜0.7 eV, the energy gap can be increased due to quantum confinement to ˜ 2eV for Ge particles of ˜3 nm in size. With a single material, Ge nanocrystals of sizes from 3 -15 nm would thus allow to span the entire range of band gaps that is of interest for photovoltaic devices. Moreover, compared to many other quantum dot materials that are currently studied for photovoltaic applications, Ge is perceived as non-toxic and environmentally benign. Ge nanocrystals are synthesized in a tubular, capacitively coupled flow through reactor. Germanium tetrachloride is used as a precursor. It is introduced into the plasma by a flow of argon and hydrogen. At typical pressures of 2 Torr and 40 W of RF power at 13.56 MHz, Ge crystals are generated and reside in the plasma for several tens of milliseconds. The size of the nanocrystals can be controlled in a range from 3-20 nm through the residence time. Particles are highly monodisperse. Organically passivated Ge nanocrystals self-assemble into monolayers when cast from colloidal solutions.

  6. High mass positive ions and molecules in capacitively-coupled radio-frequency CF4 plasmas

    NASA Astrophysics Data System (ADS)

    Schwarzenbach, W.; Cunge, G.; Booth, J. P.

    1999-06-01

    The positive ions and neutral radicals arriving at the earthed walls of a capacitively-coupled radio-frequency pure CF4 plasma were analyzed using a quadrupole mass spectrometer adapted for high masses. Experiments were performed at 50 and 200 mTorr, in an empty reactor and with Si and SiO2-coated Si substrates on the powered electrode. High mass ions and neutrals were detected, up to 500 and 300 amu, respectively. The abundance of high-mass species was greatest in the presence of silicon wafers and at higher pressure. The observed ion masses can be separated into distinct series, originating from different initial bases to which successive CF2 units have been added. We, therefore, propose that these high-mass species are the result of a gas phase polymerization process consisting of CF2 addition reactions, in agreement with a model proposed recently by our group. The influence of a silicon substrate derives primarily from the strong decrease that it induces in the concentration of F atoms, which otherwise limit the concentration of CF2 and of chain initiating species.

  7. Characteristics of capacitively coupled RF helium/neon discharges in a hollow fiber

    NASA Astrophysics Data System (ADS)

    Duan, Lian; Wang, Xinbing; Zuo, Duluo

    2016-11-01

    Capacitively coupled radio-frequency microplasmas are produced in hollow fibers with an inner diameter of hundreds of micrometers powered by an 80-MHz power supply. Considering the narrow space of the hollow core, optical emission spectrometry is used to obtain the spatially resolved characteristics of the microplasmas. The rotational temperature, excitation temperature, and electron density of microplasmas are determined based on the second positive band of nitrogen, the atomic spectra of bulk neutral particles of plasmas, and the Hβ line of the hydrogen Balmer series, respectively. In our experiments, the rotational temperature, excitation temperature, and electron density of typical inert gases helium and neon are in the ranges of 300-500 K, 7000-9500 K, and 1013 cm-3, respectively. The results obtained with different external parameters of power and pressure show that the light emission intensity increases with power and pressure. The distributions of the rotational temperature, excitation temperature, and electron density of the microplasmas are almost constant over the gap between the electrodes. These distributions are mostly insensitive to the change of power and pressure in single-component plasmas. The characteristics of mixed plasmas are also investigated. The plasma with a larger helium content possesses higher excitation temperature and lower rotational temperature and electron density than those of the plasma with a lower helium content.

  8. Effect of azimuthally asymmetric reactor components on a parallel plate capacitively coupled plasma

    SciTech Connect

    Kenney, Jason A.; Rauf, Shahid; Collins, Ken

    2009-11-15

    A three-dimensional fluid plasma model is used to investigate the impact of azimuthally asymmetric reactor components on spatial characteristics of parallel plate capacitively coupled plasmas. We consider three scenarios: high frequency (13.56 MHz) argon discharges with, separately, an off-axis circular plate surrounding the bottom electrode and an access port opening in the reactor sidewall, and a very high frequency (162 MHz) argon discharge with nonparallel electrodes. For the reactor with off-axis plate, both the Ar{sup +} density and flux are strongly perturbed toward the direction of maximum grounded surface area, with azimuthal variation in ion flux up to 10%. Perturbations in Ar{sup +} density due to the access port opening are localized to the region near the access port, and the impact on ion flux in the interelectrode region is minimal. Finally, the nonparallel electrodes result in a significant change in the location and shape of the Ar{sup +} density profile, going from a center-peaked discharge with parallel electrodes to a flattened off-center profile when tilted less than 1 deg. with a nominal 5 cm gap.

  9. Experimental investigations of the plasma radial uniformity in single and dual frequency capacitively coupled argon discharges

    NASA Astrophysics Data System (ADS)

    Zhao, Kai; Liu, Yong-Xin; Gao, Fei; Liu, Gang-Hu; Han, Dao-Man; Wang, You-Nian

    2016-12-01

    In the current work, the radial plasma density has been measured by utilizing a floating double probe in single and dual frequency capacitively coupled argon discharges operated in a cylindrical reactor, aiming at a better understanding of electromagnetic effects and exploring a method of improving the radial uniformity. The experimental results indicate that for single-frequency plasma sustained at low pressure, the plasma density radial profile exhibits a parabolic distribution at 90 MHz, whereas at 180 MHz, the profile evolves into a bimodal distribution, and both cases indicate poor uniformities. With increasing the pressure, the plasma radial uniformity becomes better for both driving frequency cases. By contrast, when discharges are excited by two frequencies (i.e., 90 + 180 MHz), the plasma radial profile is simultaneously influenced by both sources. It is found that by adjusting the low-frequency to high-frequency voltage amplitude ratio β, the radial profile of plasma density could be controlled and optimized for a wide pressure range. To gain a better plasma uniformity, it is necessary to consider the balance between the standing wave effect, which leads to a maximum plasma density at the reactor center, and the edge field effect, which is responsible for a maximum density near the radial electrode edge. This balance can be controlled either by selecting a proper gas pressure or by adjusting the ratio β.

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

    DOE PAGES

    Upadhyay, Janardan; Im, Do; Popović, Svetozar; ...

    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

  11. 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.

  12. 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.

  13. 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.

  14. 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.

  15. Diagnostics of ballistic electrons in a DC/RF hybrid capacitively coupled plasma reactor

    NASA Astrophysics Data System (ADS)

    Xu, Lin; Chen, Lee; Ranjan, Alok; Funk, Merritt; Bravenec, Ron; Economou, Demetre; Donnelly, Vincent; Sundararajan, Radha

    2008-10-01

    The DC/RF hybrid is a capacitively coupled plasma etcher with RF voltage on the bottom electrode and negative DC bias on the upper electrode. This configuration can significantly alleviate the electron shading effect and preserve photoresist integrity during plasma etching. It is thought that a group of ballistic electrons is responsible for these results. These high-energy electrons start as secondaries emitted from the negatively-biased DC electrode and accelerate across the DC sheath. They acquire high enough energy in the sheath such that they can cross the bulk plasma without gas-phase collisions. The ballistic electrons either strike the RF electrode or are trapped in the plasma bulk depending on the RF phase. Two gridded energy analyzers mounted on the back of the RF electrode were used to determine the energy distribution of ballistic electrons. The dependence of the ballistic electron energy distribution on DC voltage, pressure and RF power will be presented and compared with simulation results.

  16. An analytical model of multi-component single frequency capacitively coupled plasma and experimental validation

    NASA Astrophysics Data System (ADS)

    Saikia, Partha; Bhuyan, Heman; Favre, Mario; Wyndham, Edmund; Veloso, Felipe

    2016-09-01

    An analytical model describing the hydrogen added argon capacitively coupled plasma (CPP) is pesented and its predictions are tested with the experimental results. In the analytical model, it is found that the radio frequency (rf) current density, electron temperature and density, as well as the density of ion in multi-component plasma collectively influence the normalized sheath potential and thickness. As for low pressure rf plasma, the sheath potential is the qualitative measure of the DC self bias, the trend of variation of DC self bias with hydrogen addition is predicted in this model. The behavior of single frequency multi-component CPP is experimentally studied by a homogeneous discharge model using discharge parameters. In the experiment with hydrogen added argon plasma, the rf power as well as the working pressures are varied. The addition of hydrogen to the argon discharge leads to a decrease of electron density and DC self bias. It also results an increase of electron temperature. Agreements of the experimental results with theoretical predictions are obtained at different experimental conditions. The results obtained in this investigation could be useful for reproducibility, consistency and understanding of a particular processing application. Authors acknowledge FONDECYT grant 3160179 and 1130228. Additional funding from Conicyt PIA program ACT1108 is also acknowledged.

  17. Two-particle entanglement in capacitively coupled Mach-Zehnder interferometers

    NASA Astrophysics Data System (ADS)

    Vyshnevyy, A. A.; Lebedev, A. V.; Lesovik, G. B.; Blatter, G.

    2013-04-01

    We propose and analyze a mesoscopic device producing on-demand entangled pairs of electrons. The system consists of two capacitively coupled Mach-Zehnder interferometers implemented in a quantum Hall structure. A pair of electron wave packets is injected into the chiral edge states of two (of the four) incoming arms; scattering on the incoming interferometers splits the wave packets into four components, of which two interact. The resulting interaction phase associated with this component leads to the entanglement of the state; the latter is scattered at the outgoing beam splitter and analyzed in a Bell violation test measuring the presence of particles in the four outgoing leads. We study the two-particle case and determine the conditions to reach and observe full entanglement. We extend our two-particle analysis to include the underlying Fermi seas in the quantum Hall device; the change in shape of the wave function, the generation of electron-hole pairs in the interaction regime, and a time delay between the pulses all reduce the degree of visible entanglement and the violation of the Bell inequality, effects which we analyze quantitatively. We determine the device settings optimizing the entanglement and the Bell test and find that violation is still possible in the presence of the Fermi seas, with a maximal Bell parameter reaching B=2.18>2 in our setup.

  18. 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.

  19. 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. © 2014 American Academy of Forensic Sciences.

  20. Capacitively coupled hydrogen plasmas sustained by tailored voltage waveforms: vibrational kinetics and negative ions control

    NASA Astrophysics Data System (ADS)

    Diomede, P.; Bruneau, B.; Longo, S.; Johnson, E.; Booth, J.-P.

    2017-07-01

    A comprehensive hybrid model of a hydrogen capacitively coupled plasma, including a detailed description of the molecular vibrational kinetics, has been applied to the study of the effect of tailored voltage waveforms (TVWs) on the production kinetics and transport of negative ions in these discharges. Two kinds of TVWs are considered, valleys-to-peaks and saw-tooth, with amplitude and slope asymmetry respectively. By tailoring the voltage waveform only, it is possible to exert substantial control over the peak density and position of negative ions inside the discharge volume. This control is particularly effective for saw-tooth waveforms. Insight into the mechanisms allowing this control is provided by an analysis of the model results. This reveals the roles of the vibrational distribution function and of the electron energy distribution and their correlations, as well as changes in the negative ion transport in the electric field when using different TVWs. Considering the chemical reactivity of H- ions, the possibility of a purely electrical control of the negative ion cloud in a reactor operating with a feedstock gas diluted by hydrogen may find interesting applications. This is the first study of vibrational kinetics in the context of TVWs in molecular gases.

  1. Numerical characterization of magnetized capacitively coupled argon plasmas driven by combined dc/rf sources

    NASA Astrophysics Data System (ADS)

    Yang, Shali; Zhang, Ya; Wang, Hong-Yu; Wang, Shuai; Jiang, Wei

    2017-03-01

    The characteristics of magnetized capacitively coupled plasmas (CCPs) driven by combined dc/rf sources in argon have been investigated by a one-dimensional implicit Particle-in-cell/Monte Carlo collision model. Discharges operating at 13.56 MHz with a fixed rf voltage of 300 V are simulated at the pressure of 50 mTorr in argon. Four cases, i.e., CCP driven by rf source, rf + dc sources, rf source with magnetic field, and rf + dc sources with magnetic field, are presented and compared at the Vdc = -100 V, B = 50 Gs, and γi = 0.2. It is found that, with the influence of dc voltage and magnetic field, the plasma density has been greatly enhanced by over one order of magnitude over the rf-only case. This is due to the fact that the mean free path of electrons decreases by the cyclotron motion and the energetic secondary electrons are trapped by the magnetic field, leading to a significant increase in heating and ionization rates. Moreover, transition of the stochastic to Ohmic electron heating mechanism takes place as the magnetic field increases because electron kinetics can be strongly affected by the magnetic field. In general, we have demonstrated that such a configuration will enhance the discharge and thus enable CCPs work under extremely high energy density stably that can never be operated by any other configurations. We expect that such a configuration can promote many related applications, like etching, sputtering, and deposition.

  2. Capacitively coupled rf discharge with a large amount of microparticles: Spatiotemporal emission pattern and microparticle arrangement

    NASA Astrophysics Data System (ADS)

    Pustylnik, M. Y.; Semenov, I. L.; Zähringer, E.; Thomas, H. M.

    2017-09-01

    The effect of micron-sized particles on a low-pressure capacitively coupled rf discharge is studied both experimentally and using numerical simulations. In the laboratory experiments, microparticle clouds occupying a considerable fraction of the discharge volume are supported against gravity with the help of the thermophoretic force. The spatiotemporally resolved optical emission measurements are performed with different arrangements of microparticles. The numerical simulations are carried out on the basis of a one-dimensional hybrid (fluid-kinetic) discharge model describing the interaction between plasma and microparticles in a self-consistent way. The study is focused on the role of microparticle arrangement in interpreting the spatiotemporal emission measurements. We show that it is not possible to reproduce simultaneously the observed microparticle arrangement and emission pattern in the framework of the considered one-dimensional model. This disagreement can be attributed to the two-dimensional effects (e.g., radial diffusion of the plasma components) or to the lack of the proper description of the sharp void boundary in the frame of fluid approach.

  3. Simulations of magnetized capacitively coupled plasmas operating at constant power and voltage

    NASA Astrophysics Data System (ADS)

    Rauf, Shahid

    2005-05-01

    The impact of frequency, magnetic field and secondary electron emission on the characteristics of a magnetized capacitively coupled Ar/C2F6 plasma operating at constant power is investigated. The plasma characteristics at constant power are also compared to corresponding results for constant voltage operation. Some plasma characteristics behave similarly in the two modes of operation. For example, charged species densities increase as a function of frequency in both modes. However, unlike for constant voltage operation, charged and neutral species densities decrease with the application of a magnetic field in the constant power mode at high frequencies and at sufficiently large magnetic fields. This uncharacteristic behaviour is attributed to a substantial increase in negative ion power consumption in Ar/C2F6 when a strong magnetic field is applied. Application of the magnetic field decreases electron mobility towards the sheaths, which increases the participation of negative ions in sheath and pre-sheath dynamics. Negative ions consequently shift closer to the electrodes, negative ion power consumption increases substantially, and relatively less power is left for the electrons. Lower electron power results in the production of less charged and neutral species through electron impact processes. Simulations in Ar confirm that, without the negative ions, charged and neutral species densities increase with the application of a magnetic field at constant power. Also, for small magnetic fields, species densities increase with the magnetic field even in electronegative plasma discharges.

  4. Parametric investigations of striations in electronegative capacitively coupled radio-frequency plasmas

    NASA Astrophysics Data System (ADS)

    Liu, Yong-Xin; Schungel, Edmund; Korolov, Ihor; Donko, Zoltan; Schulze, Julian; Wang, You-Nian

    2016-09-01

    Striated structures in light emission have been observed by Phase Resolved Optical Emission Spectroscopy (PROES) and analyzed based on particle-based kinetic simulations in capacitively coupled rf CF4 plasmas. On this basis, we conduct a systematic study on the effects of external parameters on the striated structure by PROES and particle-based kinetic simulations. Our results exhibit that at 100 Pa pressure and 300 V voltage amplitude striations generally occur within a certain driving frequency range, i.e., between 2 MHz and 18 MHz, and the distance between the ion density maxima decreases with rising driving frequency. A mode discharge transition from the ``drift-ambipolar'' into ``striation'' mode could be observed by increasing the pressure or rf voltage. The reasons for these observations are further understood by the analytical solution of a simply model of the ion-ion plasma. This work has been supported by the National Natural Science Foundation of China (NSFC) (Grant Nos. 11335004 and 11405018).

  5. Surface-charging effect of capacitively coupled plasmas driven by combined dc/rf sources

    SciTech Connect

    Zhang Quanzhi; Jiang Wei; Zhao Shuxia; Wang Younian

    2010-03-15

    The surface charging effect in hybrid dc/rf capacitively coupled plasmas is investigated by particle-in-cell/Monte Carlo simulations with an equivalent-circuit module. When the thickness of the dielectric is fixed, the self-bias dc voltage induced by the charge accumulated in the dielectric first increases and then decreases with increased dc voltage. The ratio of electron-to-ion charge flowing into the dielectric increases from -1.195 to -2.582. Increasing the dc voltage results in the number of high-energy ions bombarding the dielectric decreasing. The average electron energy at the dielectric decreases to the minimum value at the biggest self-bias dc voltage in the beginning and then rapidly increases. While fixing the dc source with thickening the dielectric, the self-bias dc voltage rises, but the charge ratio decreases. The average electron energy decreases monotonically and the ion-energy distributions (IEDs) at the dielectric are shifted toward the higher energy region. The results imply that the applied dc voltage may increase the electron flux and average energy to the dielectric at the cost of reduced etching rate, which may mitigate the notching effect. The applied dc voltage can also serve as a tool to modulate the ion IEDs. At the same time, a thicker dielectric will require higher applied dc voltage.

  6. 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.

  7. Voltage distribution over capacitively coupled plasma electrode for atmospheric-pressure plasma generation

    PubMed Central

    2013-01-01

    When capacitively coupled plasma (CCP) is used to generate large-area plasma, the standing wave effect becomes significant, which results in the hindering of the uniform plasma process such as in a plasma etcher or plasma chemical vapor deposition. In this study, the transmission line modeling method is applied to calculate the voltage distribution over atmospheric-pressure CCP electrodes with the size of 1 m × 0.2 m. The measured plasma impedance in our previous study was used in the present calculation. The results of the calculations clearly showed the effects of excitation frequency and the impedance of the plasma on the form of the voltage distribution caused by the standing wave effect. In the case of 150 MHz frequency, the standing wave effect causes a drastic change in the voltage distribution via plasma ignition; however, the change is small for 13.56 MHz. It was also clarified that the power application position is important for obtaining a uniform voltage distribution. PMID:23634893

  8. 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.

  9. 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.

  10. 450 mm dual frequency capacitively coupled plasma sources: Conventional, graded, and segmented electrodes

    SciTech Connect

    Yang Yang; Kushner, Mark J.

    2010-12-01

    Wafer diameters for microelectronics fabrication will soon transition from 300 to 450 mm at a time when excitation frequencies for capacitively coupled plasmas (CCPs) are increasing to 200 MHz or higher. Already for 300 mm tools, there is evidence that wave behavior (i.e., propagation, constructive, and destructive interference) affects the uniformity of processing. The increase in diameter to 450 mm is likely to exacerbate these effects, perhaps requiring nontraditional tool designs. This is particularly important in dual frequency (DF) CCP tools in which there are potential interactions between frequencies. In this paper, results from a two-dimensional computational investigation of Ar plasma properties in a 450 mm DF-CCP reactor, incorporating a full-wave solution of Maxwell's equations, are discussed. As in 300 mm DF-CCP reactors, the electron density collapses toward the center of the reactor with increasing high frequency (HF), however, with more pronounced finite wavelength effects. Graded conductivity electrodes with multilayer of dielectrics are computationally demonstrated as a possible means to suppress wave effects thereby increasing plasma uniformity. Segmentation of the HF electrode also improves the plasma uniformity by making the electrical distance between the feeds and the sheath edges as uniform as possible.

  11. Some aspects of dissipation mechanisms in chlorine containing capacitively coupled discharges

    SciTech Connect

    Franz, Gerhard

    2006-07-15

    The temperature of gaseous neutrals in capacitively coupled discharges of chlorine, argon, and hydrogen has been measured using optical emission spectroscopy. This has been accomplished by adding small amounts of nitrogen to the ambient. The temperature can then be obtained by fitting the unresolved second rotational positive band of nitrogen. It has been found that the gaseous temperature in argon saturates for higher pressures logarithmically, whereas in chlorine, a linear behavior is observed up to the highest pressures and power inputs. Highest temperatures in chlorine have been found to be about 1100 deg. C, whereas in hydrogen, temperatures higher than 500 deg. C are rarely observed. Likewise, the effective collision frequency in chlorine increases significantly in the medium pressure range indicating a change in excitation/dissipation from the regime of stochastic heating to Ohmic heating, whereas the discharge in the inert gas still remains in the regime of stochastic heating. The experimental data for the collision frequency of the electrons with neutrals can be perfectly modeled for chlorine with these reduced gaseous densities.

  12. Voltage distribution over capacitively coupled plasma electrode for atmospheric-pressure plasma generation.

    PubMed

    Shuto, Mitsutoshi; Tomino, Fukumi; Ohmi, Hiromasa; Kakiuchi, Hiroaki; Yasutake, Kiyoshi

    2013-05-01

    When capacitively coupled plasma (CCP) is used to generate large-area plasma, the standing wave effect becomes significant, which results in the hindering of the uniform plasma process such as in a plasma etcher or plasma chemical vapor deposition. In this study, the transmission line modeling method is applied to calculate the voltage distribution over atmospheric-pressure CCP electrodes with the size of 1 m × 0.2 m. The measured plasma impedance in our previous study was used in the present calculation. The results of the calculations clearly showed the effects of excitation frequency and the impedance of the plasma on the form of the voltage distribution caused by the standing wave effect. In the case of 150 MHz frequency, the standing wave effect causes a drastic change in the voltage distribution via plasma ignition; however, the change is small for 13.56 MHz. It was also clarified that the power application position is important for obtaining a uniform voltage distribution.

  13. Direct determination of cadmium in solids using a capacitively coupled microwave plasma atomic emission spectrometer.

    PubMed

    Pless, A M; Croslyn, A; Gordon, M J; Smith, B W; Winefordner, J D

    1997-01-01

    A capacitively coupled microwave plasma (CMP) operating at 800 W was examined for the direct determination of cadmium in solids. The laboratory-constructed system contained a tungsten cup electrode capable of holding microsample quantities. A low-powered plasma was used to heat the sample, while at higher powers the plasma was used for sample vaporization and excitation. This plasma enabled thermal vaporization (TV) sample introduction to be accomplished in situ as the plasma formed directly around the sample. Thus, the need for sample preparation, procedural steps and sample transport was eliminated. This technique was capable of the direct determination of trace elements in solid samples in less than 5 min. The effects of experimental parameters such as gas flow rate, atomization power and electrode position were investigated. Detection limits obtained for Cd by TV-CMP-AES were in the picogram range with a relative standard deviation of <20%. The accuracy and precision of the method were also evaluated by measuring Cd in several NIST Standard Reference Materials.

  14. An analytical model of multi-component radio frequency capacitively coupled plasma and experimental validation

    NASA Astrophysics Data System (ADS)

    Saikia, Partha; Bhuyan, Heman; Favre, Mario; Wyndham, Edmundo; Veloso, Felipe

    2017-01-01

    An analytical model describing the hydrogen added argon radio frequency capacitively coupled plasma is presented and its predictions are tested with the experimental results. In the analytical model, it is found that the rf current density, electron temperature and density, as well as the density of light ion in multi-component plasma collectively influence the normalized sheath thickness and potential. As for low pressure rf plasma, the sheath potential is the qualitative measure of the DC self bias, the change of DC self bias with hydrogen addition is predicted in this model. The values of electron density and temperature as a function of hydrogen content in the discharge is calculated on the basis of a homogeneous discharge model using the rms values of current and voltage as well as by rf compensated Langmuir probe at different experimental conditions. In the experiment with hydrogen added argon plasma, the rf power as well as the working pressures are varied. The presence of hydrogen in the argon discharge leads to the decrease of electron density and increase of electron temperature. The measured DC self bias for the hydrogen added argon plasma is found lower than the pristine argon plasma. This decrease of DC self bias with hydrogen addition is in accordance with predictions of the theoretical model.

  15. Penetration of plasma into the wafer-focus ring gap in capacitively coupled plasmas

    SciTech Connect

    Babaeva, Natalia Y.; Kushner, Mark J.

    2007-06-01

    In plasma etching equipment for microelectronics fabrication, there is an engineered gap between the edge of the wafer and wafer terminating structures, such as focus rings. The intended purpose of these structures is to make the reactant fluxes uniform to the edge of the wafer and so prevent a larger than desired edge exclusion where useful products cannot be obtained. The wafer-focus ring gap (typically<1 mm) is a mechanical requirement to allow for the motion of the wafer onto and off of the substrate. Plasma generated species can penetrate into this gap and under the beveled edge of the wafer, depositing films and possibly creating particles which produce defects. In this paper, we report on a computational investigation of capacitively coupled plasma reactors with a wafer-focus ring gap. The penetration of plasma generated species (i.e., ions and radicals) into the wafer-focus ring gap is discussed. We found that the penetration of plasma into the gap and under the wafer bevel increases as the size of the gap approaches and exceeds the Debye length in the vicinity of the gap. Deposition of, for example, polymer by neutral species inside the gap and under the wafer is less sensitive to the size of the gap due the inability of ions, which might otherwise sputter the film, to penetrate into the gap.

  16. Influence of exciting frequency on gas and ion rotational temperatures of nitrogen capacitively coupled plasma

    SciTech Connect

    Huang, X. J.; Xin, Y.; Yuan, Q. H.; Ning, Z. Y.

    2008-07-15

    By using optical emission spectroscopy, the nitrogen gas and ion rotational temperatures in capacitively coupled plasma discharges with different exciting frequencies are investigated. The rotational temperatures are acquired by comparing the measured and calculated spectra of selected transitions with a least-square procedure. It is found that N{sub 2} gas rotational temperature minimum around 13 MHz is the combined effect of ion-dominated heating and electron-dominated heating in the plasma. The influence of exciting frequency on N{sub 2}{sup +} rotational temperature is much more than that of the N{sub 2} molecule, the lower frequency, the higher N{sub 2}{sup +} rotational temperature. Also, N{sub 2}{sup +} rotational temperature is much higher than the corresponding N{sub 2} gas rotational temperature in the plasma driven by low frequencies. These experimental phenomena may be attributed to the effective ion heating and/or possible resonant heating in the bulk plasma under the low-frequency field.

  17. 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.

  18. Influence of finite geometrical asymmetry of the electrodes in capacitively coupled radio frequency plasma

    SciTech Connect

    Bora, B. Soto, L.

    2014-08-15

    Capacitively coupled radio frequency (CCRF) plasmas are widely studied in last decades due to the versatile applicability of energetic ions, chemically active species, radicals, and also energetic neutral species in many material processing fields including microelectronics, aerospace, and biology. A dc self-bias is known to generate naturally in geometrically asymmetric CCRF plasma because of the difference in electrode sizes known as geometrical asymmetry of the electrodes in order to compensate electron and ion flux to each electrode within one rf period. The plasma series resonance effect is also come into play due to the geometrical asymmetry and excited several harmonics of the fundamental in low pressure CCRF plasma. In this work, a 13.56 MHz CCRF plasma is studied on the based on the nonlinear global model of asymmetric CCRF discharge to understand the influences of finite geometrical asymmetry of the electrodes in terms of generation of dc self-bias and plasma heating. The nonlinear global model on asymmetric discharge has been modified by considering the sheath at the grounded electrode to taking account the finite geometrical asymmetry of the electrodes. The ion density inside both the sheaths has been taken into account by incorporating the steady-state fluid equations for ions considering that the applied rf frequency is higher than the typical ion plasma frequency. Details results on the influences of geometrical asymmetry on the generation of dc self-bias and plasma heating are discussed.

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

    SciTech Connect

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

    2016-04-28

    We report investigations of capacitively coupled carbon tetrafluoride (CF{sub 4}) 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.

  20. Influences of electrode configurations in dual capacitively coupled radio frequency glow discharge plasma

    NASA Astrophysics Data System (ADS)

    Bora, B.; Soto, L.

    2015-03-01

    Capacitively coupled radio frequency (CCRF) glow discharge plasma is 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. A negative dc potential develops between the bulk plasma and the powered electrodes, which is termed as ‘self-bias’ in RF plasma. This self-bias is generated as a consequences of the geometrical asymmetry of the electrodes, which can be achieved by appropriately design the area of the powered and the grounded electrodes. However, independent control of the dc self-bias in single frequency CCRF plasma is not possible, since the changing in any operating parameters including geometrical asymmetry will also change the plasma parameters. A study on the dual frequency CCRF plasma could be useful in understanding the separate control of the dc self-bias and plasma density, which respectively determine the ion energy and ion flux. In this work, a dual frequency CCRF plasma have been studied on the basis on nonlinear global model to understand the influences of electrode sizes and proper optimization of the CCRF plasma for specific applications.

  1. Characteristics of X-Ray Emission from the PFRC-2 Capacitively Coupled Plasma

    NASA Astrophysics Data System (ADS)

    Oliver, Richard; Pearcy, Jacob; Jandovitz, Peter; Swanson, Charles; Matteucci, Jackson; Cohen, Samuel; PFRC Team

    2015-11-01

    It is uncertain what causes keV X-rays emitted from the central-cell region of a cool (bulk Te ~ 4 eV), tenuous (ne ~1010 cm-3), 5 cm diameter, weakly ionized hydrogen plasma column generated in a tandem high-mirror-ratio mirror machine (PFRC-2 device) by a low-power, external, capacitively-coupled RF (27 MHz) antenna. We explored whether the energetic electrons responsible for the X-rays exist only in the central cell (ER) or also in the asymmetric mirror regions at opposite ends of the machine, as well as how the spectra compare if they do exist in both regions. To address this, we have designed, built, calibrated, installed and operated an X-ray detector system to view the PFRC-2 region near the RF antenna in one end cell (MC). We observe somewhat different X-ray spectra emanating from the two regions. The system comprises two Amptek XR-100CR detectors with moveable slits that scan across the plasma column. Further control of radial resolution (to 0.4 cm) is afforded by changing the detector-to-slit distance. Calibrations were performed with an 55Fe source. These data are being used to understand the source of the fast electrons that create the X-rays in the MC and in the ER. This work is supported by the US DOE Contract No. DE-AC02-09CH11466 and the Princeton Environmental Institute.

  2. Modeling of microcrystalline silicon film deposition in a capacitively coupled radio-frequency plasma reactor

    SciTech Connect

    Satake, Koji; Kobayashi, Yasuyuki

    2005-01-15

    We present a numerical model of plasma-enhanced chemical-vapor deposition of hydrogenated microcrystalline silicon ({mu}c-Si:H) film from SiH{sub 4} and H{sub 2} gas mixtures in a capacitively coupled radio-frequency plasma reactor. The model takes into account electron-impact, gas-phase, and surface reactions within a well-mixed reactor model. Plasma parameters such as the electron density, the electron temperature, and the electron-impact reaction rates are determined through a discharge model and used as inputs for the reactor model. The gas-phase reactions include electron-impact and neutral-neutral reactions. Some of the surface reaction rates are determined using quantum chemical calculations and transition state theory. In the reactor model, concentrations of each chemical species are calculated at steady state using mass conservation equation uniformed throughout the reactor. Numerical results of the deposition rate as a function of the plasma reactor operating parameters show good agreement with experiments. Based on the model, the correlation between {mu}c-Si:H properties, such as the crystal grain orientation and the hydrogen content, and deposition operating parameters has been studied using a design of experiment. Finally, optimal operating parameters are investigated using optimization techniques.

  3. Etching of Niobium in an Argon-Chlorine Capacitively Coupled Plasma

    NASA Astrophysics Data System (ADS)

    Radovanov, Svetlana; Samolov, Ana; Upadhyay, Janardan; Peshl, Jeremy; Popovic, Svetozar; Vuskovic, Leposava; Applied Materials, Varian Semiconductor Team; Old Dominion University Team

    2016-09-01

    Ion assisted etching of the inner surfaces of Nb superconducting radio frequency (SRF) cavities requires control of incident ion energies and fluxes to achieve the desired etch rate and smooth surfaces. In this paper, we combine numerical simulation and experiment to investigate Ar /Cl2 capacitively coupled plasma (CCP) in cylindrical reactor geometry. Plasma simulations were done in the CRTRS 2D/3D code that self-consistently solves for CCP power deposition and electrostatic potential. The experimental results are used in combination with simulation predictions to understand the dependence of plasma parameters on the operating conditions. Using the model we were able to determine the ion current and flux at the Nb substrate. Our simulations indicate the relative importance of the current voltage phase shift and displacement current at different pressures and powers. For simulation and the experiment we have used a test structure with a pillbox cavity filled with niobium ring-type samples. The etch rate of these samples was measured. The probe measurements were combined with optical emission spectroscopy in pure Ar for validation of the model. The authors acknowledge Dr Shahid Rauf for developing the CRTRS code. Support DE-SC0014397.

  4. The response of a capacitively coupled discharge to the formation of dust particles: Experiments and modeling

    SciTech Connect

    Denysenko, I.; Berndt, J.; Kovacevic, E.; Stefanovic, I.; Selenin, V.; Winter, J.

    2006-07-15

    The influence of dust particles on the properties of a capacitively coupled Ar-C{sub 2}H{sub 2} discharge is studied both experimentally and theoretically. The results of measurements of the intensity and spatial distribution of the emitted light, the line width of the fast component of H{sub {alpha}} line and of the electron density during the particle growth are presented. To analyze the experimental results a one-dimensional discharge model is developed. Using the model the effects of dust grains on the power absorption (taking into account stochastic and Ohmic heating in the plasma sheaths), the optical emission intensity profile, the sheath size, the rf electric field and on the energy of positive ions bombarding the electrodes are investigated. In particular, it is shown that the decrease of the power absorption in the sheaths of complex plasmas is due to the dependence of the stochastic and Ohmic heating in the plasma sheaths on the electron temperature and the current flowing across the discharge plates. The results of the calculations are compared with the available experimental data and found to be in good agreement.

  5. 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.

  6. Power coupling mode transitions induced by tailored voltage waveforms in capacitive oxygen discharges

    NASA Astrophysics Data System (ADS)

    Derzsi, Aranka; Bruneau, Bastien; Gibson, Andrew Robert; Johnson, Erik; O’Connell, Deborah; Gans, Timo; Booth, Jean-Paul; Donkó, Zoltán

    2017-03-01

    Low-pressure capacitively coupled radio frequency discharges operated in O2 and driven by tailored voltage waveforms are investigated experimentally and by means of kinetic simulations. Pulse-type (peaks/valleys) and sawtooth-type voltage waveforms that consist of up to four consecutive harmonics of the fundamental frequency are used to study the amplitude asymmetry effect as well as the slope asymmetry effect at different fundamental frequencies (5, 10, and 15 MHz) and at different pressures (50–700 mTorr). Values of the DC self-bias determined experimentally and spatio-temporal excitation rates derived from phase resolved optical emission spectroscopy measurements are compared with particle-in-cell/Monte Carlo collisions simulations. The spatio-temporal distributions of the excitation rate obtained from experiments are well reproduced by the simulations. Transitions of the discharge electron heating mode from the drift-ambipolar mode to the α-mode are induced by changing the number of consecutive harmonics included in the driving voltage waveform or by changing the gas pressure. Changing the number of harmonics in the waveform has a strong effect on the electronegativity of the discharge, on the generation of the DC self-bias and on the control of ion properties at the electrodes, both for pulse-type, as well as sawtooth-type driving voltage waveforms The effect of the surface quenching rate of oxygen singlet delta metastable molecules on the spatio-temporal excitation patterns is also investigated.

  7. Heating mode transition in a hybrid direct current/dual-frequency capacitively coupled CF{sub 4} discharge

    SciTech Connect

    Zhang, Quan-Zhi; Wang, You-Nian; Bogaerts, Annemie

    2014-06-14

    Computer simulations based on the particle-in-cell/Monte Carlo collision method are performed to study the plasma characteristics and especially the transition in electron heating mechanisms in a hybrid direct current (dc)/dual-frequency (DF) capacitively coupled CF{sub 4} discharge. When applying a superposed dc voltage, the plasma density first increases, then decreases, and finally increases again, which is in good agreement with experiments. This trend can be explained by the transition between the four main heating modes, i.e., DF coupling, dc and DF coupling, dc source dominant heating, and secondary electron dominant heating.

  8. 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.

  9. Electric Field Measurements of the Capacitively Coupled Magnetized RF Sheath Utilizing Passive Optical Emission Spectroscopy

    NASA Astrophysics Data System (ADS)

    Martin, Elijah Henry

    A major challenge facing magnetic confinement fusion is the implementation of reliable plasma heating systems. Ion cyclotron resonance heating (ICRH) is a key technique utilized to achieve the ion temperatures necessary for desirable fusion reaction rates. ICRH systems are designed to couple energy into the core plasma ions through a resonant interaction with an electromagnetic wave in the radio frequency range. The interaction of the wave with the scrape off layer plasma establishes an electric field which terminates directly on the plasma facing surfaces and is referred to as the near-field. In order to bridge the gap between the theoretical and actual performance of ICRF antennas, experimental measurement of this electric field is highly desired. However, due to the large amount of power launched by ICRF antennas only non-local measurements have thus far been obtained. The research presented in this dissertation is centered on the development of a non-perturbative diagnostic to locally measure the near-field with high spatial and temporal resolution. The main objective of the research presented in this dissertation is to develop and validate a spectroscopic diagnostic capable of measuring local time periodic electric fields. The development phase of the diagnostic consisted of atomic physics formulation and was carried out in two steps. The first involved the calculation of the electronic structure of the one and two-electron atom utilizing the hydrogenic wave function. The second involved the calculation of the spectral line profile based on the electric dipole connection operator. The validate phase of the diagnostic consisted of implementation of the atomic physics to measure the electric field topology associated with the capacitively coupled magnetized RF sheath using passive OES. The experimental measurements are then compared to a simple one-dimensional analytical model providing the validation of the developed atomic physics.

  10. 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.

  11. 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.

  12. Spatial profiles of interelectrode electron density in direct current superposed dual-frequency capacitively coupled plasmas

    NASA Astrophysics Data System (ADS)

    Ohya, Yoshinobu; Ishikawa, Kenji; Komuro, Tatsuya; Yamaguchi, Tsuyoshi; Takeda, Keigo; Kondo, Hiroki; Sekine, Makoto; Hori, Masaru

    2017-04-01

    We present experimentally determined spatial profiles of the interelectrode electron density (n e) in dual-frequency capacitively coupled plasmas in which the negative direct current (dc) bias voltage (V dc) is superposed; in the experiment, 13 MHz (P low) was applied to the lower electrode and 60 MHz (P high) to the upper electrode. The bulk n e increased substantially with increases in the external power, P high, P low, and with increases in V dc. When P low was insufficient, the bulk n e decreased as the V dc bias increased. The bulk n e increased due to its dependence on V dc, especially for |V dc|  >  500 V. This may correspond to the sheath voltages (V s) of the lower electrode. The n e values in front of the upper electrode were coupled with the V dc: the V dc dependence first decreased and then increased. The dc currents (I dc) of the upper electrode were collected when a large P low was applied. The value of I dc at the threshold value of V dc  ≈  V s (e.g.  ‑500 V) increased with an increase in n e. When |V dc| exceeded the threshold, the spatial n e profile and the I dc dependence were changed relative to the electrical characteristics of the dc superposition; this led to a change in the location of the maximum n e, the width of the area of n e depletion in front of the electrodes, and a transition in the electron heating modes.

  13. Modulating effects of the low-frequency source on ion energy distributions in a dual frequency capacitively coupled plasma

    SciTech Connect

    Li Xiaosong; Bi Zhenhua; Chang Dalei; Li Zhicheng; Wang Shuai; Xu Xiang; Xu Yong; Lu Wenqi; Zhu Aimin; Wang Younian

    2008-07-21

    With the energy resolved quadrupole mass spectrometer and hybrid simulation, the influence of low-frequency (LF) source parameters on the ion energy distributions (IEDs) of argon ions impinging on the grounded electrode was studied, both experimentally and numerically, in a dual frequency capacitively coupled plasma. It was shown that for decreasing LF or increasing LF power, the high energy peak in IEDs shifts toward the high energy region significantly. The simulation results were in general agreement with the experimental data.

  14. Production of high-density capacitively coupled radio-frequency discharge plasma by high-secondary-electron-emission oxide

    SciTech Connect

    Ohtsu, Yasunori; Fujita, Hiroharu

    2004-11-22

    High-density capacitively coupled radio-frequency plasma with electron density n{sub e}>10{sup 10} cm{sup -3} was produced using MgO electrodes with a high secondary-electron-emission coefficient. It was found that in the case of MgO electrodes, both plasma density and optical emission intensity were about one order of magnitude higher than those in the case of Al electrodes.

  15. Control of electron energy distribution by the power balance of the combined inductively and capacitively coupled RF plasmas

    NASA Astrophysics Data System (ADS)

    Kim, Jin Seok; Lee, Ho-Jun; Lee, Hae June

    2016-09-01

    The control of electron energy probability function (EEPF) is important to control discharge characteristics in materials processing. For example, O radical density increases by changing the EEPF in O2 plasma, which provides high etching efficiency. The effect of the power balance between the capacitively coupled plasma (CCP) and the inductively coupled plasma (ICP) on the EEPF in Ar and O2 plasmas is investigated with a 1d3v (one-dimensional space and three-dimensional velocity domain) particle-in-cell (PIC) simulation for the combined inductively and capacitively coupled plasmas. The combined effects of the transverse electromagnetic and the longitudinal electrostatic fields are solved in PIC simulation at the same time. In a pressure range of a few mTorr, high energy electrons (>5 eV) are heated by the capacitive power in the sheath while low energy electrons (<5 eV) are heated by the inductive power in the bulk region. The EEPF has bi-Maxwellian distribution when the CCP power is dominant, but it changes to Maxwellian-like distribution with increasing inductive power. Finally, the EEPF changes to Druyvesteyn-like distribution when the inductive power is dominant.

  16. Up-regulation of expression of selected genes in human bone cells with specific capacitively coupled electric fields.

    PubMed

    Clark, Charles C; Wang, Wei; Brighton, Carl T

    2014-07-01

    The objective of the described experiments was to determine the electrical parameters that lead to optimal expression of a number of bone-related genes in cultured human bone cells exposed to a capacitively coupled electric field. Human calvarial osteoblasts were grown in modified plastic Cooper dishes in which the cells could be exposed to various capacitively coupled electric fields. The optimal duration of stimulation and optimal duration of response to the electrical field, and the optimal amplitude, frequency and duty cycle were all determined for each of the genes analyzed. Results indicated that a capacitively coupled electric field of 60 kHz, 20 mV/cm, 50% duty cycle for 2 h duration per day significantly up-regulated mRNA expression of a number of transforming growth factor (TGF)-β family genes (bone morphogenetic proteins (BMP)-2 and -4, TGF-β1, - β2 and -β3) as well as fibroblast growth factor (FGF)-2, osteocalcin (BGP) and alkaline phosphatase (ALP). Protein levels of BMP-2 and -4, and TGF-β1 and - β2 were also elevated. The clinical relevance of these findings in the context of a noninvasive treatment modality for delayed union and nonunion fracture healing is discussed.

  17. 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

    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.

  18. Electron and negative ion densities in a CW and pulsed 100 MHz capacitively coupled plasma discharge

    NASA Astrophysics Data System (ADS)

    Sirse, Nishant; Ellingboe, Bert; Tsutsumi, Takayoshi; Makoto, Sekine; Hori, Masaru

    2016-09-01

    Capacitively coupled plasma (CCP) discharges operating at a very high frequency, 30 -300 MHz, are becoming very popular now a days due to enhanced plasma processing rates and lower damage to the substrate. This is mainly achieved due to higher plasma densities and lower electron temperature produced at higher driving frequencies. Moreover, pulsing of the discharge system is known to deliver charging-free plasma processes which is highly desirable for high-aspect-ratio plasma etching. In this study, we present electron and negative ion densities in a CW and pulsed 100 MHz CCP discharge produced in O2 and Ar/O2/C4F8 gas mixture. Electron density is determined by the Hairpin probe and negative ion density is determined by the pulse laser photo-detachment combined with Hairpin probe. Photo-detachment is performed at 532, 355 and 266 nm laser wavelengths in order to selectively photo-detach different negative ions present in the discharge. Experimental results are presented for several power (100-500 W), pressure (1-10 Pa) conditions and for several duty ratios (25 - 75%) for 1 KHz pulse repetition frequency. In CW O2 plasma, we observed a similar trend in electron and negative ion density vs power, whereas, in Ar/O2/C4F8 gas mixture an opposite trend is observed in electron and negative ion density. This publication has emanated from research conducted with the financial support of Science Foundation Ireland under the International Strategic Cooperation Award Grant Number SFI/13/ISCA/2846.

  19. 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.

  20. Air-coupled MUMPs capacitive micromachined ultrasonic transducers with resonant cavities.

    PubMed

    Octavio Manzanares, Alberto; Montero de Espinosa, Francisco

    2012-04-01

    This work reports performance improvements of air-coupled capacitive micromachined ultrasonic transducers (CMUTs) using resonant cavities. In order to perform this work, we have designed and manufactured a CMUT employing multi-user microelectromechanical systems (MEMS) processes (MUMPs). The transducer was designed using Helmholtz resonator principles. This was characterised by the dimensions of the cavity and several acoustic ports, which had the form of holes in the CMUT plate. The MUMPs process has the advantage of being low cost which allows the manufacture of economic prototypes. In this paper we show the effects of the resonant cavities and acoustic ports in CMUTs using laser Doppler vibrometry and acoustical measurements. We also use Finite Element (FE) simulations in order to support experimental measurements. The results show that it is possible to enhance the output pressure and bandwidth in air by tuning the resonance frequency of the plate (f(p)) with that of the Helmholtz resonator (f(H)). The experimental measurements show the plate resonance along with an additional resonance in the output pressure spectrum. This appears due to the effect of the new resonant cavities in the transducer. FE simulations show an increase of 11 dB in the output pressure with respect to that of a theoretical vacuum-sealed cavity MUMPs CMUT by properly tuning the transducer. The bandwidth has been also analyzed by calculating the mechanical Q factor of the tuned CMUT. This has been estimated as 4.5 compared with 7.75 for the vacuum-sealed cavity MUMPs CMUT.

  1. 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.

  2. Evaluation of the capacitively coupled resistivity (line antenna) method for the characterization of vadose zone dynamics

    NASA Astrophysics Data System (ADS)

    Niu, Qifei; Wang, Yu-Hsing; Zhao, Kairan

    2014-07-01

    The electrical resistivity survey, traditionally realized by the direct current (DC) resistivity method, has shown great value for characterizing vadose zone dynamics. Compared with the DC resistivity method, the capacitively coupled (CC) resistivity method has a higher ratio of measurement speed to data density, and thus is economically preferred for resistivity surveys that require high data density, e.g., hydrological characterizations. To test the applicability of the CC resistivity method to the study of vadose zone dynamics, we conducted time-lapse resistivity surveys using a commercial CC resistivity (line antenna) system, the OhmMapper, to monitor the water content change in an unsaturated zone due to artificial rainfall infiltration. Special considerations were paid to the inversion of CC resistivity (line antenna) measurements in order to increase the accuracy of inversion results. The derived resistivity of the subsurface clearly captures the water movement in the vadose zone and shows the applicability of the CC resistivity method. The experiment also showed a limitation of the equipment: when the ground surface became extremely conductive, the OhmMapper falsely interpreted the current level. If the wrong current level is identified in the measurement, the measured resistance should be corrected accordingly. The overestimation of the ground resistivity of the CC resistivity method, arising from the decrease in the ground resistivity, was also examined and discussed. Although the measurement bias was found to be negligible in our study, one should still be cautious about it when using the CC resistivity method for similar applications, especially when the measurement is made with a short dipole cable.

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

    SciTech Connect

    Wang Mingmei; Kushner, Mark J.

    2010-01-15

    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 deg. ) can be produced incident on the wafer. The maximum energy in the high energy electron flux scales as {epsilon}{sub max}=-V{sub dc}+V{sub rf}+V{sub rf0}, for a voltage on the dc electrode of V{sub dc}, rf voltage of V{sub rf}, and dc bias on the rf electrode of V{sub rf0}. 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.

  4. Applications of the zeeman effect to analytical atomic spectroscopy--IV: capacitively-coupled radiofrequency spectral sources.

    PubMed

    Stephens, R

    1977-04-01

    A magnetically-stable spectral source is described in which a radiofrequency plasma is generated within a single hollow-cathode electrode. Power is coupled to the plasma by placing metal electrodes at the radiofrequency supply potential, around the outside of the lamp-casing. The sources are simple to build, and the capacitive power-coupling technique is convenient for generating a plasma at any desired point within the envelope. The performance of the sources is compared with that of the corresponding commercial hollow-cathode lamps driven from a direct current supply.

  5. Methylmercury determination in seafood by photochemical vapor generation capacitively coupled plasma microtorch optical emission spectrometry.

    PubMed

    Covaci, Eniko; Senila, Marin; Ponta, Michaela; Darvasi, Eugen; Petreus, Dorin; Frentiu, Maria; Frentiu, Tiberiu

    2017-08-01

    A non-chromatographic method based on double liquid-liquid extraction and measurements by UV photochemical vapor generation capacitively coupled plasma microtorch optical emission spectrometry was developed and characterized for methylmercury determination in seafood. Samples were prepared following the procedure recommended in JRC Technical Report of European Commission formerly proposed for the determination of methylmercury in seafood by thermal decomposition atomic absorption spectrometry, namely confinement of Hg species in 47% HBr solution, extraction of CH3Hg(+) in toluene and back-extraction in 1% l-cysteine aqueous solution. Mercury cold vapor was generated by flow injection UV photo-reduction from CH3Hg(+) in 0.6molL(-1) HCOOH, while quantification was performed against external Hg(2+) aqueous standards and measuring Hg 253.652nm emission using a low power/Ar consumption plasma microtorch (15W, 100mLmin(-1)) and a low resolution microspectrometer (Ocean Optics). The figures of merit and analytical capability were assessed by analyzing certified reference materials and test samples of fish fillet and discussed in relation with requirements for Hg determination in seafood in European legislation (Decisions 2007/333/EC and 2002/657/EC) as well as compared to performances achieved in thermal decomposition atomic absorption spectrometry. The limit of detection and quantification of 2µgkg(-1) and 6µgkg(-1) respectively, precision of 2.7-9.4% and accuracy of 99±8% of the proposed method for the determination of CH3Hg(+) fulfill the demands of European legislation for Hg quantification. The limit of detection and quantification were better than those in the used reference method or other non-/chromatographic methods taken for comparison. The analysis of certified reference materials and the Bland and Altman test performed on 12 test samples confirmed trueness of the proposed method and its reliability for the determination of traces of CH3Hg(+) with 95

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

    SciTech Connect

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

    2013-01-14

    A one-dimensional particle-in-cell (PIC) model is used to examine the energy distribution of electron flux at electrodes [labeled g{sub e}({epsilon},t), where {epsilon} 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 g{sub e}({epsilon},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 g{sub e}({epsilon},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 g{sub e}({epsilon}) and electron temperature in the plasma (T{sub e}) can be easily established. Below 4.67 Pa, kinetic effects become important, making it difficult to interpret g{sub e}({epsilon}) in terms of T{sub e}. At low pressures, g{sub e}({epsilon},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 T{sub e} and secondary electrons retaining a larger fraction of the energy they gained during initial sheath acceleration. For the relatively small DC voltages examined ( Double-Vertical-Line V{sub dc} Double-Vertical-Line /V{sub rf} {<=} 0.15), the application of a negative DC voltage on an electrode decreases the electron flux there but has a weak impact on the g{sub e} profile.

  7. 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'.

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

    PubMed Central

    Ren, Shangjie; Dong, Feng

    2016-01-01

    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

  9. A comparative evaluation between conditions of the wrist band capacitively-coupled ECG recording through signal-to-noise ratio.

    PubMed

    Nakamura, Hideo; Shimada, Koichiro; Fujie, Tatsuro

    2007-01-01

    The purpose of this study is to evaluate the performance to measure ECG recording based on signal-to-noise ratio of ECG signals recorded with three types of electrodes in four experimental conditions for discussion on appropriate form of the electrodes. The wrist band shaped capacitively-coupled electrodes have been developed. We evaluated the signal-to-noise ratios with statistical methods when the reference and the properties of the electrodes were substituted. From our results, it is indicated that not only performance of the electrodes themselves but also stabilization of electrodes around skin are important for steady ECG recording.

  10. Optimization of dry etching parameters for fabrication of polysilicon waveguides with smooth sidewall using a capacitively coupled plasma reactor.

    PubMed

    Cheemalapati, Surya; Ladanov, Mikhail; Winskas, John; Pyayt, Anna

    2014-09-01

    In this paper, we demonstrate the optimization of a capacitively coupled plasma etching for the fabrication of a polysilicon waveguide with smooth sidewalls and low optical loss. A detailed experimental study on the influences of RF plasma power and chamber pressure on the roughness of the sidewalls of waveguides was conducted and waveguides were characterized using a scanning electron microscope. It was demonstrated that optimal combination of pressure (30 mTorr) and power (150 W) resulted in the smoothest sidewalls. The optical losses of the optimized waveguide were 4.1±0.6  dB/cm.

  11. Spatially and frequency-resolved monitoring of intradie capacitive coupling by heterodyne excitation infrared lock-in thermography

    NASA Astrophysics Data System (ADS)

    León, J.; Perpiñà, X.; Altet, J.; Vellvehi, M.; Jordà, X.

    2013-02-01

    This paper combines the infrared lock-in thermography (IR-LIT) and heterodyne excitation techniques to detect high-frequency capacitive currents due to intradie electrical coupling between microelectronic devices or more complex systems. Modulating the excitation with the heterodyne approach, we drive devices or complex systems with high frequency electrical signals in such a way that they behave as low frequency heat sources, modulating their temperature field at a frequency detectable by an IR-LIT system. This approach is analytically studied and extended to a bi-dimensional scenario, showing that the thermal information at low frequency depends on the electrical characteristics of the sample at high frequency.

  12. Effect of bulk electric field reversal on the bounce resonance heating in dual-frequency capacitively coupled electronegative plasmas

    SciTech Connect

    Liu Yongxin; Zhang Quanzhi; Liu Jia; Song Yuanhong; Wang Younian; Bogaerts, Annemie

    2012-09-10

    The electron bounce resonance heating (BRH) in dual-frequency capacitively coupled plasmas operated in oxygen and argon has been studied by different experimental methods. In comparison with the electropositive argon discharge, the BRH in an electronegative discharge occurs at larger electrode gaps. Kinetic particle simulations reveal that in the oxygen discharge, the bulk electric field becomes quite strong and is out of phase with the sheath field. Therefore, it retards the resonant electrons when traversing the bulk, resulting in a suppressed BRH. This effect becomes more pronounced at lower high-frequency power, when the discharge mode changes from electropositive to electronegative.

  13. 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.

  14. 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.

  15. Numerical simulation of strongly coupled binary ionic plasmas

    SciTech Connect

    DeWitt, H.; Slattery, W.; Chabrier, G.

    1995-11-01

    New lengthy Monte Carlo simulations of the energy equation of state of binary ionic mixture fluids in a uniform background show that deviations from the linear mixing rule are small, positive, and nearly constant as a function of {Gamma}. Deviations from linear mixing for the Helmholtz free energy are positive and behave as ln{Gamma}. Quantitative results are obtained form the correction to the thermonuclear reaction rate.

  16. 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.

  17. Probe diagnostics of argon-oxygen-tetramethyltin capacitively coupled plasmas for the deposition of tin oxide thin films

    SciTech Connect

    Pulpytel, J.; Morscheidt, W.; Arefi-Khonsari, F.

    2007-04-01

    Langmuir probe measurements in nondepositing and depositing rf capacitively coupled (CCP) plasmas are briefly reviewed and compared to the results obtained in our rf system used for the deposition of tin oxide (SnO{sub 2}) thin films from argon-oxygen-tetamethyltin [Sn(CH{sub 3}){sub 4}] plasmas. Typically in our experimental conditions for tin oxide deposition, values of kT{sub eff}= 1.2-1.5 eV and n{sub e}=3-5x10{sup 9} cm{sup -3} were measured. These values are consistent with those generally reported in other depositing discharges. The shape of the electron energy probability function (EEPF), obtained from the Druyvesteyn procedure, was discussed too. As a consequence of the two electron heating mechanisms in capacitively coupled discharges, that is, ohmic and stochastic heating, the electrons have a bi-Maxwellian EEPF at low pressure (in the range of 10-100 mTorr). Moreover, a deep 'hole' appears in the EEPF at the energy which could correspond to the resonant peak of the vibrational excitation cross section of some molecules which can be present in the discharge, such as N{sub 2}, CH{sub 4}, or CO.

  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. Formation of silicon nitride nanopillars in dual-frequency capacitively coupled plasma and their application to Si nanopillar etching

    SciTech Connect

    Park, C. K.; Kim, H. T.; Kim, D. Y.; Lee, N.-E.

    2007-07-15

    During the etching process of a silicon nitride layer in CH{sub 2}F{sub 2}/H{sub 2}/Ar dual-frequency superimposed capacitively coupled plasmas, CH{sub x}F{sub y} polymer nanodots were formed on the silicon nitride surface and, as a result, silicon nitride nanopillars were fabricated. The H{sub 2} and low frequency power (P{sub LF}) were found to play a critical role in determining the density and diameters of the pillars due to the change in the degree of hydrofluorocarbon polymerization. Silicon nitride nanopillars with a diameter as small as congruent with 25 nm and an aspect ratio as large as congruent with 3.2 were formed, and silicon nanopillars could also be fabricated by the inductively coupled Cl{sub 2}/Ar plasma etching of a Si substrate using the silicon nitride nanopillars as a hard mask.

  20. 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.

  1. Phase and charge re-entrant phase transitions in two capacitively coupled Josephson arrays with ultrasmall junctions

    SciTech Connect

    Ramirez-Santiago, Guillermo; Jose, Jorge V.

    2004-11-01

    We have studied the phase diagram of two capacitively coupled Josephson junction arrays with charging energy, E{sub c}, and Josephson coupling energy, E{sub J}. Our results are obtained using a path integral Quantum Monte Carlo algorithm. The parameter that quantifies the quantum fluctuations in the ith array is defined by {alpha}{sub i}{identical_to}E{sub c{sub i}}/E{sub J{sub i}}. Depending on the value of {alpha}{sub i}, each independent array may be in the semiclassical or in the quantum regime: We find that thermal fluctuations are important when {alpha}{<=}1.5 and the quantum fluctuations dominate when 2.0{<=}{alpha}. Vortices are the dominant excitations in the semiclassical limit, while in the quantum regime the charge excitations are important. We have extensively studied the interplay between vortex and charge dominated individual array phases. The phase diagrams for each array as a function of temperature and interlayer capacitance were determined from results for their helicity modulus, {upsilon}({alpha}), and the inverse dielectric constant, {epsilon}{sup -1}({alpha}). The two arrays are coupled via the capacitance C{sub inter} at each site of the lattices. When one of the arrays is in the quantum regime and the other one is in the semiclassical limit, {upsilon}(T,{alpha}) decreases with T, while {epsilon}{sup -1}(T,{alpha}) increases. This behavior is due to a duality relation between the two arrays: e.g., a manifestation of the gauge invariant capacitive interaction between vortices in the semiclassical array and charges in the quantum array. We find a re-entrant transition in {upsilon}(T,{alpha}), at low temperatures, when one of the arrays is in the semiclassical limit (i.e., {alpha}{sub 1}=0.5) and the quantum array has 2.0{<=}{alpha}{sub 2}{<=}2.5, for the values considered for the interlayer capacitance of C{sub inter}=0.26087, 0.52174, 0.78261, 1.04348, and 1.30435. Similar results were obtained for larger values of {alpha}{sub 2}=4.0 with C

  2. Phase-shift effect in capacitively coupled plasmas with two radio frequency or very high frequency sources

    SciTech Connect

    Xu Xiang; Zhao Shuxia; Zhang Yuru; Wang Younian

    2010-08-15

    A two-dimensional fluid model was built to study the argon discharge in a capacitively coupled plasma reactor and the full set of Maxwell equations is included in the model to understand the electromagnetic effect in the capacitive discharge. Two electrical sources are applied to the top and bottom electrodes in our simulations and the phase-shift effect is focused on. We distinguish the difference of the phase-shift effect on the plasma uniformity in the traditional radio frequency discharge and in the very high frequency discharge where the standing wave effect dominates. It is found that in the discharges with frequency 13.56 MHz, the control of phase difference can less the influence of the electrostatic edge effect, and it gets the best radial uniformity of plasma density at the phase difference {pi}. But in the very high frequency discharges, the standing wave effect plays an important role. The standing wave effect can be counteracted at the phase difference 0, and be enhanced at the phase difference {pi}. The standing wave effect and the edge effect are balanced at some phase-shift value between 0 and {pi}, which is determined by discharge parameters.

  3. 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. Copyright © 2014 Elsevier Inc. All rights reserved.

  4. Capacitive Deionization: a coupled 2D electro-adsorption/convective-diffusive simulation for various system configurations

    NASA Astrophysics Data System (ADS)

    Hidrovo, Carlos; Salamat, Yasamin

    2016-11-01

    Capacitive Deionization (CDI) is a relatively new electrically based desalination method that uses porous media to adsorb ions in solution from water, with the potential to recover part of the energy used during the desalination process. Previous studies have investigated the physics underlying the electro-adsorption process in the electrical double layers in the CDI porous electrodes. In order to improve CDI performance in terms of minimum average concentration, total amount of water treated, and duration of the desalination process, herein we propose and evaluate different CDI architectures. Two previously validated 2D and 1D models are used alongside each other to study different CDI system configurations based on various convective-diffusive layer regimes. Moreover, the effects of micro pore and macro pore capacities on the total number of ions adsorbed in the porous media is investigated. This will open new opportunities for further researches toward engineered CDI units for better desalination.

  5. 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.

  6. One-dimensional hybrid simulation of the dc/RF combined driven capacitively coupled CF{sub 4} plasmas

    SciTech Connect

    Wang Shuai; Xu Xiang; Wang Younian

    2012-11-15

    We developed a one-dimensional hybrid model to simulate the dc/RF combined driven capacitively coupled plasma for CF{sub 4} discharges. The numerical results show the influence of the dc source on the plasma density distribution, ion energy distributions (IEDs), and ion angle distributions (IADs) on both RF and dc electrodes. The increase of dc voltage impels more ions with high energy to the electrode applied to the dc source, which makes the IEDs at the dc electrode shift toward higher energy and the peaks in IADs shift toward the small angle region. At the same time, it also decreases ion-energy at the RF electrode and enlarges the ion-angles which strike the RF electrode.

  7. Spatial evolution of the electron energy distribution function in a low-pressure capacitively coupled plasma containing argon and krypton

    NASA Astrophysics Data System (ADS)

    Zhu, Xi-Ming; Chen, Wen-Cong; Li, Jiang; Cheng, Zhi-Wen; Pu, Yi-Kang

    2012-08-01

    The spatial evolution of the electron energy distribution function (EEDF) in the axial direction of a capacitively coupled plasma with two parallel plate electrodes is investigated using an optical emission line-ratio method for Ar/Kr discharges. When the rf power is increased from 25 to 400 W at a pressure of 400 mTorr, we observe a transition from convex EEDFs to concave ones and a sharp increase in electron density, due to an α-γ mode transition, which is believed to be caused by the high-energy electrons originating in the high-voltage sheath. We also investigate the spatial evolution of the EEDF when the pressure is increased from 45 to 500 mTorr at a power of 100 W. The EEDF is uniform at pressures below 180 mTorr and becomes non-uniform at higher pressures, owing to the decrease in the energy relaxation length of the high-energy electrons.

  8. Determination of non-metallic elements by capacitively coupled helium microwave plasma atomic emission spectrometry with capillary gas chromatography.

    PubMed

    Uchida, H; Berthod, A; Winefordner, J D

    1990-07-01

    A capacitively coupled microwave helium plasma with a tubular tantalum electrode was evaluated as an element selective detector for gas chromatography (GC). The end of a 10-m bonded fused capillary column was directly inserted into the tubular electrode without any switching system. A heated copper tube was used to house the part of the GC column that protruded from the oven. The optimisation of operating parameters, line selection, background emission and horizontal and vertical observation position is described. Analytical figures of merit including sensitivity, reproducibility, signal to background ratio, selectivity, dynamic range and limit of detection (LOD), were evaluated for carbon, hydrogen, chlorine and bromine emission. Limits of detection in the low ng range (20 pmol) were obtained for halogenated compounds using carbon emission, whereas LODs in the 0.1 micrograms range (2 nmol) were obtained using chlorine or bromine emission lines.

  9. 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.

  10. Analysis of optical emission spectroscopy in a dual-frequency capacitively coupled CHF{sub 3} plasma

    SciTech Connect

    Huang Xiaojiang; Xin Yu; Yang Lei; Ye Chao; Yuan Qianghua; Ning Zhaoyuan

    2009-04-15

    The characteristics of a capacitively coupled CHF{sub 3} plasma driven by dual-frequency sources (41 MHz/2 MHz) are experimentally investigated by using optical emission spectroscopy technique. The dependences of relative densities of F and H, the ratio of F/CF{sub 2}, and the excitation temperature, as well as neutral gas rotational temperature on the low or high frequency (LF or HF) power, have been analyzed. It is found that the increment rate of the gas dissociation rate, the ratio of F/CF{sub 2}, the excitation temperature. and the neutral gas temperature with increasing LF power are larger than that of HF power. The relative densities of F and H, the ratio of F/CF{sub 2}, and the excitation temperature decrease while the neutral gas temperature increases with increasing gas pressure.

  11. Control of the discharge chemistry of CHF{sub 3} in dual-frequency capacitively coupled plasmas

    SciTech Connect

    Yuan, Q. H.; Ye, C.; Xin, Y.; Huang, X. J.; Ning, Z. Y.; Yin, G. Q.

    2008-08-18

    The discharge chemistry of CHF{sub 3} in 27/2, 60/2, and 60/13.56 MHz dual-frequency capacitively coupled plasmas (DF-CCPs) is studied with actinometric optical emission spectroscopy and mass spectrometry. The frequency effect on the generation of reactive species was investigated. The reactive radicals and the density ratio of F/CF{sub 2} could be controlled by the 2 MHz rf power in 27/2 and 60/2 MHz DF-CCPs. The density ratios of F/CF{sub 2} in 27/2 and 60/2 MHz DF-CCPs are observed to increase with an increase in low-frequency power. However, this control could not be obtained in 60/13.56 MHz DF-CCP.

  12. The CHIC Model: A Global Model for Coupled Binary Data

    ERIC Educational Resources Information Center

    Wilderjans, Tom; Ceulemans, Eva; Van Mechelen, Iven

    2008-01-01

    Often problems result in the collection of coupled data, which consist of different N-way N-mode data blocks that have one or more modes in common. To reveal the structure underlying such data, an integrated modeling strategy, with a single set of parameters for the common mode(s), that is estimated based on the information in all data blocks, may…

  13. Capacitive electrodes in electroencephalography.

    PubMed

    von Ellenrieder, Nicolás; Spinelli, Enrique; Muravchik, Carlos H

    2006-01-01

    We present a forward problem formulation for computing biopotentials measured with dry or capacitive electrodes. This formulation is not quasistatic and has mixed boundary conditions. Our results show that simple approximations to the measurements based on capacitive coupling are adequate in most situations. We study the range of validity and errors committed in the EEG forward and inverse problems when using this approximation.

  14. Capacitive Power Transfer

    DTIC Science & Technology

    2010-12-15

    capacitive charger achieves near 80% e ciency at 3.7W with only 63 pF of coupling capacitance. An automatic tuning loop adjusts the frequency from...find the optimum circuit component values and operating point. A prototype capacitive charger achieves near 80% efficiency at 3.7 W with only 63 pF of...delivery in a smartphone sized package . Section 5 presents work in progress on a capacitively isolated LED driver. 2 Analysis The analysis is based on a

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

    SciTech Connect

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

    2016-06-15

    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.

  16. 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.

  17. Fluid simulation of species concentrations in capacitively coupled N2/Ar plasmas: Effect of gas proportion

    NASA Astrophysics Data System (ADS)

    Liang, Ying-Shuang; Liu, Gang-Hu; Xue, Chan; Liu, Yong-Xin; Wang, You-Nian

    2017-05-01

    A two-dimensional self-consistent fluid model and the experimental diagnostic are employed to investigate the dependencies of species concentrations on the gas proportion in the capacitive N2/Ar discharges operated at 60 MHz, 50 Pa, and 140 W. The results indicate that the N2/Ar proportion has a considerable impact on the species densities. As the N2 fraction increases, the electron density, as well as the Ar+ and Arm densities, decreases remarkably. On the contrary, the N2 + density is demonstrated to increase monotonically with the N2 fraction. Moreover, the N density is observed to increase significantly with the N2 fraction at the N2 fractions below 40%, beyond which it decreases slightly. The electrons are primarily generated via the electron impact ionization of the feed gases. The electron impact ionization of Ar essentially determines the Ar+ density. For the N2 + production, the charge transition process between the Ar+ ions and the feed gas N2 dominates at low N2 fraction, while the electron impact ionization of N2 plays the more important role at high N2 fraction. At any gas mixtures, more than 60% Arm atoms are generated through the radiative decay process from Ar(4p). The dissociation of the feed gas N2 by the excited Ar atoms and by the electrons is responsible for the N formation at low N2 fraction and high N2 fraction, respectively. To validate the simulation results, the floating double probe and the optical emission spectroscopy are employed to measure the total positive ion density and the emission intensity originating from Ar(4p) transitions, respectively. The results from the simulation show a qualitative agreement with that from the experiment, which indicates the reliable model.

  18. Breaking Binaries? Biomedicine and Serostatus Borderlands among Couples with Mixed HIV Status.

    PubMed

    Persson, Asha; Newman, Christy E; Ellard, Jeanne

    2017-02-28

    With recent breakthroughs in HIV treatment and prevention, the meanings of HIV-positivity and HIV-negativity are changing at biomedical and community levels. We explore how binary constructions of HIV serostatus identities are giving way to something more complex that brings both welcome possibilities and potential concerns. We draw on research with couples with mixed HIV status to argue that, in the context of lived experiences, serostatus identities have always been more ambiguous than allowed for in HIV discourse. However, their supposed dichotomous quality seems even more dubious now in view of contemporary biomedical technologies. Invoking the anthropological concept of "borderlands," we consider how biomedicine is generating more diverse serostatus identities, widening the options for how to live with HIV, and eroding the stigmatizing serostatus binary that has haunted the epidemic. But we also ask whether this emerging borderland, and its "normalizing" tendencies, is concomitantly giving rise to new and troubling binaries. [Figure: see text].

  19. A capillary electrophoresis system with dual capacitively coupled contactless conductivity detection and electrospray ionization tandem mass spectrometry.

    PubMed

    Francisco, Kelliton José Mendonça; do Lago, Claudimir Lucio

    2016-07-01

    A commercial system that is comprised of a CE coupled to an ESI triple quadrupole mass spectrometer was equipped with two capacitively coupled contactless conductivity detectors (C(4) Ds). The first C(4) D was positioned inside the original cartridge, and the second C(4) D was positioned as close as possible to the ESI probe entrance by using a 3D-printed support. The C(4) Ds electropherograms were matched to the ESI-MS electropherogram by correcting their timescales by the factor LT /LD , where LT and LD are the total capillary length and the length until the C(4) D, respectively. A general approach for method development supporting the simultaneous conductivity and MS detection is discussed, while application examples are introduced. These examples include the use of C(4) D as a simple device that dismiss the use of an EOF marker, a low-selectivity detector that continuously provide information about unexpected features of the sample, and even a detector that can be more sensitive than ESI-MS. The C(4) D used in this setup proved to have a smaller contribution to the peak broadening than ESI-MS, which allowed that a C(4) D, positioned at 12 cm from the inlet of an 80-cm-long capillary, could be used to foresee position and shape of the peaks being formed 6.8 times slower at the ESI-MS electropherogram.

  20. 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.

  1. Performance enhancement of an air-coupled multiple moving membrane capacitive micromachined ultrasonic transducer using an optimized middle plate configuration

    NASA Astrophysics Data System (ADS)

    Emadi, Arezoo; Buchanan, Douglas

    2016-10-01

    A multiple moving membrane capacitive micromachined ultrasonic transducer has been developed. This transducer cell structure includes a second flexible plate suspended between the transducer top plate and the fixed bottom electrode. The added plate influences the transducer top plate deflection map and, therefore, the transducer properties. Three series of individual air-coupled, dual deflectable plate transducers and two 1×27 element transducer arrays were fabricated using multiuser microelectromechanical systems (MEMS) processes (MUMPs). Each set of transducers included devices with middle plate radii from 22% to 65% of the corresponding transducer top plate radius. The effect of the transducer middle plate configuration has been investigated. Electrical, optical, and acoustic characterizations were conducted and the results were compared with the simulation findings. It was found that the transducer top plate amplitude of vibration is significantly enhanced with a wider middle deflectable plate. The electrical and optical measurement results are shown to be in good agreement with simulation results. The acoustic measurement results indicated a 37% increase in the amplitude of transmitted signal by the 1-MHz air-couple transducer when its middle plate radius was increased by 35%.

  2. 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. 2010 John Wiley & Sons, Ltd.

  3. 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}.

  4. Nonlinear modes in binary bosonic condensates with pseudo-spin-orbital coupling

    NASA Astrophysics Data System (ADS)

    Zezyulin, D. A.; Driben, R.; Konotop, V. V.; Malomed, B. A.

    2013-07-01

    We consider an effectively one-dimensional binary Bose-Einstein condensate (BEC) with nonlinear repulsive interactions and linear spin-orbit (SO) and Zeeman-splitting couplings. In the presence of the trapping harmonic-oscillator (HO) potential, we report the existence of even, odd, and asymmetric spatial modes. They feature alternating domains with opposite directions of the pseudospin, i.e., antiferromagnetic structures, which is explained by the interplay of the linear couplings, HO confinement, and repulsive self-interaction. The number of the domains is determined by the strength of the SO coupling. The modes are constructed analytically in the weakly nonlinear system. The dynamical stability of the modes is investigated by means of the Bogoliubov-de Gennes equations and direct simulations. A notable result is that the multi-domain-wall (DW) structures are stable, alternating between odd and even shapes, while the simplest single-DW structure is unstable. Thus, the system features a transition to the complex ground states under the action of the SO coupling. The addition of the Zeeman splitting transforms the odd modes into asymmetric ones via spontaneous symmetry breaking. The results suggest possibilities for switching the binary system between states with opposite (pseudo)magnetization by external fields, and realization of similar stable states and dynamical effects in solid-state and nonlinear-optical settings emulated by the SO-coupled BECs.

  5. Negative resistance phenomenon in dual-frequency capacitively coupled plasma-enhanced chemical vapor deposition system for photovoltaic manufacturing process

    NASA Astrophysics Data System (ADS)

    Kwon, H. C.; Aman-ur-Rehman, Won, I. H.; Park, W. T.; Lee, J. K.

    2012-01-01

    The validity of effective frequency concept is investigated for dual-frequency (DF) capacitively coupled plasma (CCP) discharges by using particle-in-cell/Monte Carlo collision simulations. This concept helps in analyzing DF CCP discharges in a fashion similar to single-frequency (SF) CCP discharges with effective parameters. Unlike the driving frequency of SF CCP discharges, the effective frequency in DF CCP is dependent on the ratio of the two driving currents (or voltages) and this characteristic makes it possible to control the ion flux and the ion bombardment energy independently. This separate control principally allows to increase the ion flux and plasma density for high deposition rates, while keeping the ion mean energy constant at low values to prevent the bombardment of highly energetic ions at the substrate surface to avoid unwanted damage in the solar cell manufacturing. The abrupt transition of the effective frequency leads to the phenomenon of negative resistance which is one of the several physical phenomena associated uniquely with DF CCP discharges. Using effective frequency concept, the plasma characteristics have been investigated in the negative resistance regime for solar cell manufacturing.

  6. Hybrid Modeling of SiH4/Ar Discharge in a Pulse Modulated RF Capacitively Coupled Plasma

    NASA Astrophysics Data System (ADS)

    Xi-Feng, Wang; Yuan-Hong, Song; You-Nian, Wang; PSEG Team

    2015-09-01

    Pulsed plasmas have offered important advantages in future micro-devices, especially for electronegative gas plasmas. In this work, a one-dimensional fluid and Monte-Carlo (MC) hybrid model is developed to simulate SiH4/Ar discharge in a pulse modulated radio-frequency (RF) capacitively coupled plasma (CCP). Time evolution densities of different species, such as electrons, ions, radicals, are calculated, as well as the electron energy probability function (EEPF) which is obtained by a MC simulation. By pulsing the RF source, the electron energy distributions and plasma properties can be modulated by pulse frequency and duty cycle. High electron energy tails are obtained during power-on period, with the SiHx densities increasing rapidly mainly by SiH4 dissociation. As the RF power is off, the densities in the bulk region decrease rapidly owing to high energy electrons disappear, but increase near electrodes since diffusion without the confinement of high electric field, which can prolong the time of radials deposition on the plate. Especially, in the afterglow, the increase of negative ions near the electrodes results from cool electron attachment, which are good for film deposition. This work was supported by the National Natural Science Foundation of China (Grant No. 11275038).

  7. 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).

  8. Ionization of elements in medium power capacitively coupled argon plasma torch with single and double ring electrodes.

    PubMed

    Ponta, Michaela; Frentiu, Maria; Frentiu, Tiberiu

    2012-06-01

    A medium power, low Ar consumption capacitively coupled plasma torch (275 W, 0.4 L min-1) with molybdenum tubular electrode and single or two ring electrodes in non-local thermodynamic equilibrium (LTE) was characterized with respect to its ability to achieve element ionization. Ionization degrees of Ca, Mg, Mn and Cd were determined from ionic-to-atomic emission ratio and ionization equilibrium according to Saha's equation. The ionization degrees resulted from the Saha equation were higher by 9-32% than those obtained from spectral lines intensity in LTE regime and closer to reality. A linear decrease of ionization with increase of ionization energy of elements was observed. Plasma torch with two ring electrodes provided higher ionization degrees (85 ± 7% Ca, 79 ± 7% Mn, 80 ± 7% Mg and 73 ± 8% Cd) than those in single ring arrangement (70 ± 6% Ca, 57 ± 7% Mn, 57 ± 8% Mg and 42 ± 9% Cd). The Ca ionization decreased linearly by up to 79 ± 4% and 53 ± 6% in plasma with two ring electrodes and single ring respectively in the presence of up to 400 µg mL-1 Na as interferent. The studied plasma was effective in element ionization and could be a potential ion source in mass spectrometry.

  9. 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.

  10. 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.

  11. 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.

  12. Separation and determination of degradation products of acid orange 7 by capillary electrophoresis/capacitively coupled contactless conductivity detector.

    PubMed

    Wang, Xin; Xiong, Ya; Xie, Tianyao; Sharma, Virender K; Tu, Yuting; Yang, Jiannan; Tian, Shuanghong; He, Chun

    2013-07-15

    Capillary electrophoresis (CE) with capacitively coupled contactless conductivity detector (C(4)D) was developed to separate azo-dyestuff acid orange 7 (AO7) and its six degradation products. The analyzed products were sulfamic acid, oxalic acid, benzenesulfonic acid, 4-hydroxybenzene sulfonic acid, phthalic acid, and 4-aminobenzene sulfonic acid. In developing the method, types and concentrations of running buffers, injecting voltage and time, and applied voltage were tested to obtain optimum conditions to analyze target compounds. The separation was successfully achieved within 10 min using a fused-silica capillary under the following conditions: 20 mmol L(-1) acetate acid buffer, electrokinetic injection of -12 kV × 10 s, and applied voltage of -13 kV. The developed method was applied to analyze degradation products in situ during the reaction of AO7 with Fenton reagent (Fe(II)+H2O2 at pH 4.0). Copyright © 2013 Elsevier B.V. All rights reserved.

  13. 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.

  14. A simulation of a capacitively coupled oxygen discharge using the oopd1 particle-in-cell Monte Carlo code

    NASA Astrophysics Data System (ADS)

    Gudmundsson, J. T.; Lieberman, M. A.; Wang, Ying; Verboncoeur, J. P.

    2009-10-01

    The oopd1 particle-in-cell Monte Carlo (PIC-MC) code is used to simulate a capacitively coupled discharge in oxygen. oopd1 is a one-dimensional object-oriented PIC-MC code [1] in which the model system has one spatial dimension and three velocity components. It contains models for planar, cylindrical, and spherical geometries and replaces the XPDx1 series [2], which is not object-oriented. The revised oxygen model includes, in addition to electrons, the oxygen molecule in ground state, the oxygen atom in ground state, the negative ion O^-, and the positive ions O^+ and O2^+. The cross sections for the collisions among the oxygen species have been significantly revised from earlier work using the xpdp1 code [3]. Here we explore the electron energy distribution function (EEDF), the ion energy distribution function (IEDF) and the density profiles for various pressures and driving frequencies. In particular we investigate the influence of the O^+ ion on the IEDF, we explore the influence of multiple driving frequencies, and we do comparisons to the previous xpdx1 codes. [1] J. P. Verboncoeur, A. B. Langdon, and N. T. Gladd, Comp. Phys. Comm. 87 (1995) 199 [2] J. P. Verboncoeur, M. V. Alves, V. Vahedi, and C. K. Birdsall, J. Comp. Physics 104 (1993) 321 [2] V. Vahedi and M. Surendra, Comp. Phys. Comm. 87 (1995) 179

  15. Calculation of the electrode shape for suppression of the standing wave effect in large area rectangular capacitively coupled reactors

    SciTech Connect

    Sansonnens, L.

    2005-03-15

    The electromagnetic standing wave becomes one of the main sources of plasma nonuniformity in large area capacitively coupled rf reactors. In cylindrical reactors with a central rf connection or one-dimensional linear reactors with rf connections at both extremities, Gaussian shaped electrodes can be used to suppress this standing wave. In this work, we present a two-dimensional quasiplanar circuit model and a numerical method for calculation of the electrode shape that can suppress the standing wave effect in large area rectangular reactors. It is shown that the calculated shapes are not Gaussian, and are not only a function of the reactor dimensions and excitation frequency, but are also strongly influenced by the position and number of rf connections, as will also be the case for a cylindrical reactor with a noncentral rf connection. However, when a shape has been determined for a given reactor geometry and rf excitation frequency, then it is shown that it remains independent of the plasma provided that the electromagnetic skin depth in the plasma remains large enough such that skin effects remain negligible.

  16. 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.

  17. Heating mechanisms and particle flow balancing of capacitively coupled plasmas driven by combined dc/rf sources

    SciTech Connect

    Jiang Wei; Xu Xiang; Dai Zhongling; Wang Younian

    2008-03-15

    Heating mechanisms and particle flow balancing of capacitively coupled plasmas driven by combined dc/rf sources have been investigated by particle-in-cell/Monte Carlo simulations. At low pressure, Ohmic heating will be suppressed and stochastic heating will be enhanced while increasing dc voltage. But the overall heating power will decrease. No heating mode transitions are observed. At high pressure, bulk plasma density decreases at low dc and rf voltage, and the one-side {alpha}-{gamma} transition will occur while increasing dc voltage. After the transition, the plasma density abruptly increases and average electron energy drops. As the result of that, the plasma is sustained by secondary electrons instead of the Ohmic heating of the bulk electrons. The dc source will reduce, or even eliminate at high voltage, the electron charge flowing into the dc powered electrode. Therefore the ratio of electron-to-ion charge flowing into the rf powered electrode over one period increases from -1.0 to -2.0--2.3 for low pressure and -2.2--5.0 for high pressure.

  18. 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.

  19. Striations in electronegative capacitively coupled radio-frequency plasmas: Effects of the pressure, voltage, and electrode gap

    NASA Astrophysics Data System (ADS)

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

    2017-07-01

    Capacitively coupled radio-frequency (CCRF) CF4 plasmas have been found to exhibit a self-organized striated structure at operating conditions, where the plasma is strongly electronegative and the ion-ion plasma in the bulk region (largely composed of CF3+ and F- ions) resonates with the excitation frequency. In this work, we explore the effects of the gas pressure, the RF voltage, and the electrode gap on this striated structure by phase resolved optical emission spectroscopy and particle-in-cell/Monte Carlo collisions simulations. The measured electronic excitation patterns at different external parameters show a good general agreement with the spatio-temporal plots of the ionization rate obtained from the simulations. For a fixed driving frequency, the minima of the CF3+ or F- ion densities (between the density peaks in the bulk) are comparable and independent of other external parameters. However, the ion density maxima generally increase as a function of the pressure or RF voltage, leading to the enhanced spatial modulation of plasma parameters. The striation gap (defined as the distance between two ion density peaks) is approximately inversely proportional to the pressure, while it exhibits a weak dependence on the RF voltage and the electrode gap. A transition between the striated and non-striated modes can be observed by changing either the pressure or the RF voltage; for 13.56 and 18 MHz driving frequencies, we present a phase diagram as a function of the pressure and voltage amplitude parameters.

  20. Experimental investigation of ion energy distributions in a dual frequency capacitively coupled Ar/CF{sub 4} plasma

    SciTech Connect

    Li Zhicheng; Chang Dalei; Li Xiaosong; Bi Zhenhua; Lu Wenqi; Xu Yong; Zhu Aimin; Wang Younian

    2010-03-15

    An energy resolved quadrupole mass spectrometer was adopted to determine ion energy distributions (IEDs) impinging on the ground electrode in a dual frequency (DF) capacitively coupled Ar/CF{sub 4} (95%/5%) plasma. The influences of discharge parameters, such as power of low frequency (LF power) source, frequency of LF source (LF frequency), and gas pressure, on IEDs of Ar{sup +} and CF{sub 3}{sup +} were investigated. The enhancement in LF power, which hence means the increase in sheath potential, results in a significant shift in the IEDs of Ar{sup +} and CF{sub 3}{sup +} toward higher energy area and then a broader energy width. However, the increase in LF frequency leads to narrow and unimodal IEDs, which is probably because the regime of DF CCP has changed during the process. The pressure has a remarkable effect on IEDs structure, i.e., the exhibited saddle-shaped structure of IEDs is obvious in a collisionless sheath at lower pressure but becomes eliminated in a collision sheath at higher pressure. The Ar{sup +} IEDs have low energy regions because of the ion-atomic resonant charge transfer process, while CF{sub 3}{sup +} ions do not. In addition, some of the experimental results are compared with simulation corresponding to our previous work, and general agreements are obtained.

  1. Numerical investigation of ion-energy-distribution functions in single and dual frequency capacitively coupled plasma reactors.

    PubMed

    Georgieva, V; Bogaerts, A; Gijbels, R

    2004-02-01

    Ion-energy-distribution functions (IEDFs) are numerically investigated in capacitively coupled (cc) radio frequency (rf) Ar/CF(4)/N(2) discharges by a one-dimensional particle-in-cell/Monte Carlo model. The simulation considers electron-neutral collisions, various kinds of collisions of ions (Ar+, CF+3, N+2, F-, and CF-3) with neutral, positive-negative ion, and electron-ion recombination. The influence of pressure, applied voltage amplitude, and applied frequency on the Ar+, CF+3, and N+2 IEDFs is presented. The dependence on the frequency regime is investigated by simulations of the Ar/CF(4)/N(2) mixture in single (13.56 MHz) and dual frequency (2+27 MHz or 1+27 MHz) cc reactors. A comparison of the simulation results with analytical calculations in a collisionless rf sheath is discussed. The results show that the IEDFs shift toward the low energies with increasing pressure or decreasing applied voltage amplitude. The Ar+ and N+2 IEDFs exhibit secondary maxima due to the charge transfer collisions. The CF+3 IEDF has a peak at high energies in consistency with the average sheath potential drop. The IEDFs in the dual frequency regime are broad and bimodal.

  2. 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).

  3. Comparison of 2D Hybrid Simulational and Experimental Results for Dual-Frequency Capacitively Coupled Argon Plasmas

    NASA Astrophysics Data System (ADS)

    Bi, Zhenhua; Xu, Xiang; Liu, Yongxin; Jiang, Xiangzhan; Lu, Wenqi; Wang, Younian

    2011-04-01

    A two-dimensional hybrid simulation scheme is proposed to study the characteristics of dual-frequency (DF) capacitively coupled plasma (CCP) discharge based on the geometry of real device. Given the experimental parameters for argon plasma, the output from the fluid module such as ion density, number flux, electron temperature and the Monte-Carlo collision (MCC) results of ion energy distribution function (IEDF) as well as electron energy distribution function (EEDF) are obtained and discussed in detail. A novel complete floating double probe is designed to measure both density and temperature of electron and a quadrupole mass spectrometer is also equipped for IEDF investigations. The measurements on the density of bulk plasma, electron temperature and IEDF agree well, qualitatively, with the simulated results. A comparison with experimental results indicates that, since the structure of real device is taken into account, this model is capable of describing the global dynamic characteristics occurred in DF-CCP and presenting more reliable results than the model with an ideal chamber structure.

  4. Modeling of Deep Si Etching in Two-Frequency Capacitively Coupled Plasma in SF6/O2

    NASA Astrophysics Data System (ADS)

    Hamaoka, Fukutaro; Yagisawa, Takashi

    2007-10-01

    We developed the simulation model of deep Si etching for MEMS fabrication. This model includes the physical effect of ions under the presence of plasma molding, chemical etching by radicals, and the formation of a passivation layer on the wafer. The simulation was carried out in SF6/O2 in two-frequency capacitively coupled plasma using an extended vertically integrated computer aided design for device processing (VicAddress). We estimated the local characteristics of plasma structures (such as potential distribution, ion velocity distribution) near an artificial microscale hole pattern on the wafer. In this case, the sheath thickness is comparable to or even smaller than the size of the hole. Thus, the sheath tends to wrap around the hole on the wafer. The distorted sheath field directly affects the incident flux and velocity distributions of ions. The angular distribution of ions at the edge of the hole is strongly distorted from the normal incidence. The ion flux becomes radially nonuniform in the vicinity of the hole pattern. That is, the etching profile is distorted particularly at the bottom corner because of the removal of the passivation layer by energetic ion under the presence of plasma molding.

  5. Determination of fluoroacetate and fluoride in blood serum by capillary zone electrophoresis using capacitively coupled contactless conductivity detection.

    PubMed

    Vidal, Denis Tadeu Rajh; Augelli, Marcio Antonio; Hotta, Guilherme Minoru; Lopes, Fernando Silva; do Lago, Claudimir Lucio

    2011-04-01

    Fluoroacetate is a highly toxic species naturally found in plants and in commercial products (compound 1080) for population control of several undesirable animal species. However, it is non-selective and toxic to many other animals including humans, and thus its detection is very important for forensic purposes. This paper presents a sensitive and fast method for the determination of fluoroacetate in blood serum using capillary electrophoresis with capacitively coupled contactless conductivity detection. Serum blood samples were treated with ethanol to remove proteins. The samples were analyzed in BGE containing 15 mmol/L histidine and 30 mmol/L gluconic acid (pH 3.85). The calibration curve was linear up to 75 μmol/L (R² =0.9995 for N=12). The detection limit in the blood serum was 0.15 mg/kg, which is smaller than the lethal dose for humans and other animals. Fluoride, a metabolite of the fluoroacetate defluorination, could also be detected for levels greater than 20 μmol/L, when polybrene was used for reversion of the EOF. CTAB and didecyldimethylammonium bromide are not useful for this task because of the severe reduction of the fluoride level. However, no interference was observed for fluoroacetate.

  6. Numerical simulation of capacitively coupled RF plasma flowing through a tube for the synthesis of silicon nanocrystals

    NASA Astrophysics Data System (ADS)

    Le Picard, Romain; Song, Sang-Heon; Porter, David; Kushner, Mark; Girshick, Steven

    2014-10-01

    Silicon nanocrystals (SiNCs) are of interest for applications in the photonics, electronics, and biomedical areas. Nonthermal plasmas offer several potential advantages for synthesizing SiNCs. In this work, we have developed a numerical model of a capacitively coupled RF plasma used for the synthesis of SiNCs. The plasma, consisting of silane diluted in argon at a total pressure of about 2 Torr, flows through a narrow quartz tube with two ring electrodes. The numerical model is 2D, assuming axisymmetry. An aerosol sectional model is added to the Hybrid Plasma Equipment Model developed by Kushner and coworkers. The aerosol module solves for aerosol size distributions and size-dependent charge distributions. A detailed chemical kinetic mechanism considering silicon hydride species containing up to 5 Si atoms is used to model particle nucleation and surface growth. The sectional model calculates coagulation, particle transport by electric force, neutral drag and ion drag, and particle charging using orbital motion limited theory. Simulation results are presented for selected operating conditions, and are compared to experimental results. This work was partially supported by the US Dept. of Energy Office of Fusion Energy Science (DE-SC0001939), the US National Science Foundation (CHE-124752), and the Minnesota Supercomputing Institute.

  7. Synthesis, transport, and retention of tin nanodroplets in a magnetron sputtering source combined with a capacitively-coupled plasma

    NASA Astrophysics Data System (ADS)

    Sasaki, K.; Takanari, K.

    2016-09-01

    The intention of this work was the development of a method for coating metal nanodroplets with thin films having high melting temperatures. To realize this process technology, we combined a magnetron sputtering plasma for synthesizing metal nanoparticles with a capacitively-coupled plasma (CCP) for retaining and heating synthesized nanoparticles. The magnetron sputtering source with a tin target was operated at a high pressure of 400 mTorr. The high pressure induced the condensation of tin atoms in the gas phase, resulting in the formation of tin nanoparticles. The nanoparticles were transported downward, and were trapped in the sheath electric field near the planar electrode for the CCP discharge. The formation, the transport, and the retention of nanoparticles were monitored by laser light scattering. Collected tin nanoparticles did not have agglomerated shapes, suggesting that tin nanoparticles were melted when they were stored in the CCP discharge. The surfaces of tin nanoparticles were oxidized. When we introduced methane before the collection, we observed core-shell nanoparticles without oxidization. Tin nanoparticles were coated with amorphous carbon films by plasma-enhanced chemical vapor deposition of methane.

  8. 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).

  9. Numerical modelling for the optimization of multi-element, capacitive, ultrasonic, air-coupled transducer

    NASA Astrophysics Data System (ADS)

    Zhang, D.; Rénier, M.; Castaings, M.

    2013-08-01

    This paper presents an analytical method to predict the acoustic pressure field produced in the air by concentric, annular sources. The sources correspond to a multi-element, ultrasonic, air-coupled array, which should be used further for non-destructive testing (NDT) purposes. After validation of the model based on the comparison of the predicted acoustic pressure with experimental results, a numerical study of the consequence of the annular sources arrangement on the acoustic field is realized. This helps in optimizing the design of the array, so that the intended ultrasonic field is produced. For high spatial resolution to be obtained in further NDT process this field should be focused and, ideally, the frequency used for inspecting the tested piece should be tuned so that wavelengths in the inspected material take suitable values in regards of piece thickness and defect sizes. Numerical simulations show that the multi-element array allows dynamic focussing to be made by judiciously adjusting delay laws of the excitation signals applied to each individual element.

  10. 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

  11. Classical Spin-Orbit Coupling and Periastron Advance in a Binary Pulsar

    NASA Technical Reports Server (NTRS)

    Kaspi, V. M.; Bailes, M.; Manchester, R. N.; Stappers, B. W.; Bell, J. F.

    1996-01-01

    We report on radio timing observations of PSR J0045-7319, and eccentric pulsar/B star 51-day binary in the Small Magellanic Cloud. Significant deviations from a simple Keplerian orbit, observed as precessions of the periastron longitude and orbital plane, are identified with classical spin-orbit coupling and apsidal advance, for the fist time in a binary pulsar. Both precessions result from the B star's rotationally-induced gravitational quadropole moment, however, the orbital plane precession requires the B star's spin axis to be inclined with respect to the orbital angular momentum. We constrain this inclination angle (theta) to be 25(deg) <(theta)<41(deg). Under the conventional assumption that the pre-supernova angular momenta were aligned, our observations provide the most direct evidence yet for an asymmetric supernova.

  12. Preliminary investigation of a medium power argon radiofrequency capacitively coupled plasma as atomization cell in atomic fluorescence spectrometry of cadmium.

    PubMed

    Frentiu, Tiberiu; Darvasi, Eugen; Senila, Marin; Ponta, Michaela; Cordos, Emil

    2008-09-15

    The single ring electrode radiofrequency capacitively coupled plasma torch (SRTr.f.CCP) operated at 275W, 27.12 MHz and Ar flow rate below 0.7 lmin(-1) was investigated for the first time as atomization cell in atomic fluorescence spectrometry (AFS) using electrodeless discharge lamps (EDL) as primary radiation source and charged coupled devices as detector. The signal to background ratio (SBR) and limit of detection for Cd determination by EDL-SRTr.f.CCP-AFS were compared to those obtained in atomic emission spectrometry using the same plasma torch. The detection limit in fluorescence was 4.3 ngml(-1) Cd compared to 65 ngml(-1) and 40 ngml(-1) reported in r.f.CCP-atomic emission (AES) equipped with single or double ring electrode. The lower detection limit in EDL-SRTr.f.CCP-AFS is due to a much better SBR in fluorescence. The limit of detection was also compared to those in atomic fluorescence with inductively coupled plasma (0.4 ngml(-1)), microwave plasma torch (0.25 ngml(-1)) and air-acetylene flame (8 ngml(-1)). The influence of light-scattering through the plasma and the secondary reflection of the primary radiation on the wall of the quartz tube on the analytical performance are discussed. The non-spectral matrix effects of Ca, Mg and easily ionized elements are much lower in EDL-SRTr.f.CCP-AFS compared to SRTr.f.CCP-AES. The new technique was applied in the determination of Cd in contaminated soils, industrial hazardous waste (0.4-370 mgkg(-1)) and water (113 microgl(-1)) with repeatability of 4-8% and reproducibility in the range of 5-12%, similar to those in ICP-AES. The results were checked by the analysis of a soil and water CRM with a recovery degree of 97+/-9% and 98+/-4%, for a confidence limit of 95%. The present EDL-SRTr.f.CCP-AFS is a promising technique for Cd determination in environmental samples.

  13. Dynamics of High-Order Spin-Orbit Couplings about Linear Momenta in Compact Binary Systems*

    NASA Astrophysics Data System (ADS)

    Huang, Li; Wu, Xin; Mei, Li-Jie; Huang, Guo-Qing

    2017-09-01

    This paper relates to the post-Newtonian Hamiltonian dynamics of spinning compact binaries, consisting of the Newtonian Kepler problem and the leading, next-to-leading and next-to-next-to-leading order spin-orbit couplings as linear functions of spins and momenta. When this Hamiltonian form is transformed to a Lagrangian form, besides the terms corresponding to the same order terms in the Hamiltonian, several additional terms, third post-Newtonian (3PN), 4PN, 5PN, 6PN and 7PN order spin-spin coupling terms, yield in the Lagrangian. That means that the Hamiltonian is nonequivalent to the Lagrangian at the same PN order but is exactly equivalent to the full Lagrangian without any truncations. The full Lagrangian without the spin-spin couplings truncated is integrable and regular. Whereas it is non-integrable and becomes possibly chaotic when any one of the spin-spin terms is dropped. These results are also supported numerically.

  14. Investigation of the electron kinetics in O2 capacitively coupled plasma with the use of a Langmuir probe

    NASA Astrophysics Data System (ADS)

    Kechkar, S.; Swift, P.; Kelly, S.; Kumar, S.; Daniels, S.; Turner, M.

    2017-06-01

    A Langmuir probe was used to measure various electron plasma parameters in O2 capacitively coupled plasma. It was shown that the variation in these plasma parameters was due to changes in the electron heating mechanisms as the discharge conditions varied. The so called ‘α-γ’ mode transition in O2 plasma (100 mTorr) was identified from the power evolution (30-600 W) of the electron energy probability function (EEPF), electron density (n e) and effective electron temperature (T eff). The EEPF evolved from Druyvesteyn to bi-Maxwellian with increasing applied power which resulted in a rapid decrease and an abrupt increase in T eff and n e respectively. Comparisons were made to the same mode transition for similar conditions in Ar plasma. The EEPFs were Druyvesteyn in the α mode and evolved into a Maxwellian like EEPF in the γ mode of an Ar plasma. Two distinct trends of n e versus power was observed, it was shown that the measured rf current and rf voltage had a similar behavior. The pressure evolution of the EEPF, n e, and T eff was also investigated in O2 plasma operated at both 30 and 200 W. At 30 W the number of high energy electrons decreased and flattening of the low energy portion of the EEPF occurred with increasing gas pressure (10-100 mTorr) which indicates a collisionless to collisional heating transition. However, at 200 W the right combination of rf voltage and pressure was met for the discharge to evolve into the γ mode as the pressure increased. This was evident from significant narrowing of the EEPF as the pressure increased.

  15. Numerical analysis of the effect of electrode spacing on deposition rate profiles in a capacitively coupled plasma reactor

    NASA Astrophysics Data System (ADS)

    Kim, Ho Jun; Lee, Hae June

    2016-12-01

    The effect of reactor dimension on deposition rate profiles is analyzed with a two-dimensional (2D) fluid simulation of a capacitively coupled plasma (CCP) reactor to deposit a hydrogenated silicon nitride (SiN x H y ) film with a SiH4/NH3/N2/He gas mixture. We focus on the complex function of electrode spacing to reveal the physical relation between reactor geometry and deposition rate profiles. The simulation demonstrates that the localization of electron density is concentrated close to the powered electrode periphery for electrode spacing of 9 mm. However, the plasma distribution becomes bulk dominated with electrode spacing of 15 mm by relaxing the localization. As a result, the increase in the electrode spacing creates a more uniform electron power density profile, and the deposition rate profile of SiN x H y film changes from convex to concave in a radial direction. The change in the deposition rate profile is validated through comparison with the experimental observation, which agrees well with the simulation results with errors of less than 5%. The deposition rate profile with electrode spacing of 9 mm is very sensitive to the non-uniform gas density condition applied to the showerhead inlet. However, the deposition rate profile with electrode spacing of 15 mm is not sensitive to the inlet gas profile because of the increasing residence time. The increase of the electrode spacing promotes molecule-molecule gas phase reactions and consequently weakens the effect of the inlet boundary condition.

  16. Space and phase resolved ion energy and angular distributions in single- and dual-frequency capacitively coupled plasmas

    SciTech Connect

    Zhang, Yiting; Kushner, Mark J.; Moore, Nathaniel; Pribyl, Patrick; Gekelman, Walter

    2013-11-15

    The control of ion energy and angular distributions (IEADs) is critically important for anisotropic etching or deposition in microelectronic fabrication processes. With single frequency capacitively coupled plasmas (CCPs), the narrowing in angle and spread in energy of ions as they cross the sheath are definable functions of frequency, sheath width, and mean free path. With increases in wafer size, single frequency CCPs are finding difficulty in meeting the requirement of simultaneously controlling plasma densities, ion fluxes, and ion energies. Dual-frequency CCPs are being investigated to provide this flexible control. The high frequency (HF) is intended to control the plasma density and ion fluxes, while the ion energies are intended to be controlled by the low frequency (LF). However, recent research has shown that the LF can also influence the magnitude of ion fluxes and that IEADs are determined by both frequencies. Hence, separate control of fluxes and IEADs is complex. In this paper, results from a two-dimensional computational investigation of Ar/O{sub 2} plasma properties in an industrial reactor are discussed. The IEADs are tracked as a function of height above the substrate and phase within the rf cycles from the bulk plasma to the presheath and through the sheath with the goal of providing insights to this complexity. Comparison is made to laser-induced fluorescence experiments. The authors found that the ratios of HF/LF voltage and driving frequency are critical parameters in determining the shape of the IEADs, both during the transit of the ion through the sheath and when ions are incident onto the substrate. To the degree that contributions from the HF can modify plasma density, sheath potential, and sheath thickness, this may provide additional control for the IEADs.

  17. Electromembrane extraction of amino acids from body fluids followed by capillary electrophoresis with capacitively coupled contactless conductivity detection.

    PubMed

    Strieglerová, Lenka; Kubáň, Pavel; Boček, Petr

    2011-09-16

    Electromembrane extraction (EME) proved to be a simple and rapid pretreatment method for analysis of amino acids and related compounds in body fluid samples. Body fluids were acidified to the final concentration of 2.5 M acetic acid and served as donor solutions. Amino acids, present as cations in the donor solutions, migrated through a supported liquid membrane (SLM) composed of 1-ethyl-2-nitrobenzene/bis-(2-ethylhexyl)phosphonic acid (85:15 (v/v)) into the lumen of a porous polypropylene hollow fiber (HF) on application of electric field. The HF was filled with 2.5 M acetic acid serving as the acceptor solution. Matrix components in body fluids were efficiently retained on the SLM and did not interfere with subsequent analysis. Capillary electrophoresis with capacitively coupled contactless conductivity detection was used for determination of 17 underivatized amino acids in background electrolyte solution consisting of 2.5 M acetic acid. Parameters of EME, such as composition of SLM, pH and composition of donor and acceptor solution, agitation speed, extraction voltage, and extraction time were studied in detail. At optimized conditions, repeatability of migration times and peak areas of 17 amino acids was better than 0.3% and 13%, respectively, calibration curves were linear in a range of two orders of magnitude (r(2)=0.9968-0.9993) and limits of detection ranged from 0.15 to 10 μM. Endogenous concentrations of 12 amino acids were determined in EME treated human serum, plasma, and whole blood. The method was also suitable for simple and rapid pretreatment and determination of elevated concentrations of selected amino acids, which are markers of severe inborn metabolic disorders. Copyright © 2011 Elsevier B.V. All rights reserved.

  18. Combined effects of gas pressure and exciting frequency on electron energy distribution functions in hydrogen capacitively coupled plasmas

    SciTech Connect

    Abdel-Fattah, E.; Sugai, H.

    2013-02-15

    The combined effects of the variation of hydrogen pressure (40-400 mTorr) and exciting frequency (13.56-50 MHz) on the electron energy probability function (EEPF) and other plasma parameters in capacitively coupled hydrogen H{sub 2} discharge at fixed discharge voltage were investigated using rf-compensated Langmuir probe. At a fixed exciting frequency of 13.56 MHz, the EEPF evolved from Maxwellian-like distribution to a bi-Maxwellian distribution when the H{sub 2} pressure increased, possibly due to efficient vibrational excitation. The electron density largely increased to a peak value and then decreased with the increase of H{sub 2} pressure. Meanwhile, the electron temperature and plasma potential significantly decrease and reaching a minimum at 120 mTorr beyond, which saturated or slightly increases. On the other hand, the dissipated power and electron density markedly increased with increasing the exciting frequency at fixed H{sub 2} pressure and voltage. The electron temperatures negligibly dependent on the driving frequency. The EEPFs at low pressure 60 mTorr resemble Maxwellian-like distribution and evolve into a bi-Maxwellian type as frequency increased, due to a collisonless (stochastic) sheath-heating in the very high frequency regime, while the EEPF at hydrogen pressure {>=}120 mTorr retained a bi-Maxwellian-type distribution irrespective of the driving frequency. Such evolution of the EEPFs shape with the driving frequency and hydrogen pressure has been discussed on the basis of electron diffusion processes and low threshold-energy inelastic collision processes taking place in the discharge. The ratio of stochastic power to bulk power heating ratio is dependent on the hydrogen pressure while it is independent on the driving frequency.

  19. On singlet metastable states, ion flux and ion energy in single and dual frequency capacitively coupled oxygen discharges

    NASA Astrophysics Data System (ADS)

    Hannesdottir, H.; Gudmundsson, J. T.

    2017-05-01

    We apply particle-in-cell simulations with Monte Carlo collisions to study the influence of the singlet metastable states on the ion energy distribution in single and dual frequency capacitively coupled oxygen discharges. For this purpose, the one-dimensional object-oriented particle-in-cell Monte Carlo collision code oopd1 is used, in which the discharge model includes the following nine species: electrons, the neutrals O(3P) and O{{}2}≤ft({{\\text{X}}3} Σ g-\\right. ), the negative ions O-, the positive ions O+ and O2+ , and the metastables O(1D), O{{}2}≤ft({{\\text{a}}1}{{ Δ }g}\\right) and O2(b{{}1} Σ g+ ). Earlier, we have explored the effects of adding the species O{{}2}≤ft({{\\text{a}}1}{{ Δ }g}\\right. ) and O2(b{{}1} Σ g+ ), and an energy-dependent secondary electron emission yield for oxygen ions and neutrals, to the discharge model. We found that including the two molecular singlet metastable states decreases the ohmic heating and the effective electron temperature in the bulk region (the electronegative core). Here we explore how these metastable states influence dual frequency discharges consisting of a fundamental frequency and the lowest even harmonics. Including or excluding the detachment reactions of the metastables O{{}2}≤ft({{\\text{a}}1}{{ Δ }g}\\right. ) and O2(b{{}1} Σ g+ ) can shift the peak electron temperature from the grounded to the powered electrode or vice versa, depending on the phase difference of the two applied frequencies. These metastable states can furthermore significantly influence the peak of the ion energy distribution for O2+ -ions bombarding the powered electrode, and hence the average ion energy upon bombardment of the electrode, and lower the ion flux.

  20. 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.

  1. 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.

  2. Fano-like anti-resonances in strongly coupled binary Coulomb systems

    NASA Astrophysics Data System (ADS)

    Silvestri, L.; Kalman, G. J.; Donkó, Z.; Hartmann, P.; Kählert, H.

    2015-01-01

    Molecular-dynamics (MD) simulations of a strongly coupled binary ionic mixture have revealed the appearance of sharp minima in the species-resolved dynamical density fluctuation spectra. This phenomenon is reminiscent of the well-known Fano anti-resonance, occurring in various physical processes. We give a theoretical analysis using the quasi-localized charge approximation, and demonstrate that the observed phenomenon in the equilibrium spectrum is a novel manifestation of the Fano mechanism, that occurs at characteristic frequencies of the system different from the conventional classical Fano frequencies.

  3. 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)

  4. Plasma etching of dielectric materials using inductively and capacitively coupled fluorocarbon discharges: Mechanistic studies of the surface chemistry

    NASA Astrophysics Data System (ADS)

    Ling, Li

    Fluorocarbon (FC) plasmas are commonly used for dielectric materials etching. Our initial work was performed using an inductively coupled plasma (ICP) system to produce FC discharges. We first examined the effect of CO addition to C4F8 or C4F8/Ar plasmas for selective etching of organosilicate glass (OSG), which is a typical low k (LK) material over etch stop layers. The chemical activity of CO when added to either C4F8 Or C4F8/80% Ar can be understood in terms of the CO dissociation energy threshold relative to energies of inelastic electron collision processes of the dominant feedgas component. We also studied the plasma etching behavior of 193 nm and 248 nm photoresist in FC discharges used for dielectric etching. We showed that ion-enhanced selective volatilization of carbonyl groups of the 193 nm photoresist polymer backbone which is absent for the 248 nm material, along with modulation of the ion-interaction with the photoresist material by fluorocarbon surface passivation, may be responsible for the introduction of pronounced surface roughness of 193 nm photoresists. Current industrial efforts are aimed primarily at capacitively coupled plasma (CCP) systems. A home-built dual frequency CCP reactor was used to investigate additional aspects of dielectric materials plasma etching. We designed a gap structure to simulate sidewall surface processes occurring during high aspect ratio trench etching. In particular, we showed that the FC film deposition rates measured using the gap structure qualitatively correlate with the trench sidewall angles produced in LK dielectrics in both C 4F8/Ar and CF4/H2 based gas chemistries: The lower the FC deposition rate on the sidewall, the more vertical the trench sidewall. This approach was used to study surface chemistry aspects of FC film deposition with and without ion bombardment. For the gap structure film deposition takes place without ion bombardment and we observed a novel FC film growth phenomenon in pure C4F8 plasmas

  5. Fully parameterized model of a voltage-driven capacitive coupled micromachined ohmic contact switch for RF applications

    NASA Astrophysics Data System (ADS)

    Heeb, Peter; Tschanun, Wolfgang; Buser, Rudolf

    2012-03-01

    A comprehensive and completely parameterized model is proposed to determine the related electrical and mechanical dynamic system response of a voltage-driven capacitive coupled micromechanical switch. As an advantage over existing parameterized models, the model presented in this paper returns within few seconds all relevant system quantities necessary to design the desired switching cycle. Moreover, a sophisticated and detailed guideline is given on how to engineer a MEMS switch. An analytical approach is used throughout the modelling, providing representative coefficients in a set of two coupled time-dependent differential equations. This paper uses an equivalent mass moving along the axis of acceleration and a momentum absorption coefficient. The model describes all the energies transferred: the energy dissipated in the series resistor that models the signal attenuation of the bias line, the energy dissipated in the squeezed film, the stored energy in the series capacitor that represents a fixed separation in the bias line and stops the dc power in the event of a short circuit between the RF and dc path, the energy stored in the spring mechanism, and the energy absorbed by mechanical interaction at the switch contacts. Further, the model determines the electrical power fed back to the bias line. The calculated switching dynamics are confirmed by the electrical characterization of the developed RF switch. The fabricated RF switch performs well, in good agreement with the modelled data, showing a transition time of 7 µs followed by a sequence of bounces. Moreover, the scattering parameters exhibit an isolation in the off-state of >8 dB and an insertion loss in the on-state of <0.6 dB up to frequencies of 50 GHz. The presented model is intended to be integrated into standard circuit simulation software, allowing circuit engineers to design the switch bias line, to minimize induced currents and cross actuation, as well as to find the mechanical structure dimensions

  6. 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.

  7. 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

  8. 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.

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

    PubMed

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

    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.

  10. 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.

  11. Quaternary sediment architecture in the Orkhon Valley (central Mongolia) inferred from capacitive coupled resistivity and Georadar measurements

    NASA Astrophysics Data System (ADS)

    Mackens, Sonja; Klitzsch, Norbert; Grützner, Christoph; Klinger, Riccardo

    2017-09-01

    Detailed information on shallow sediment distribution in basins is required to achieve solutions for problems in Quaternary geology, geomorphology, neotectonics, (geo)archaeology, and climatology. Usually, detailed information is obtained by studying outcrops and shallow drillings. Unfortunately, such data are often sparsely distributed and thus cannot characterise entire basins in detail. Therefore, they are frequently combined with remote sensing methods to overcome this limitation. Remote sensing can cover entire basins but provides information of the land surface only. Geophysical methods can close the gap between detailed sequences of the shallow sediment inventory from drillings at a few spots and continuous surface information from remote sensing. However, their interpretation in terms of sediment types is often challenging, especially if permafrost conditions complicate their interpretation. Here we present an approach for the joint interpretation of the geophysical methods ground penetrating radar (GPR) and capacitive coupled resistivity (CCR), drill core, and remote sensing data. The methods GPR and CCR were chosen because they allow relatively fast surveying and provide complementary information. We apply the approach to the middle Orkhon Valley in central Mongolia where fluvial, alluvial, and aeolian processes led to complex sediment architecture. The GPR and CCR data, measured on profiles with a total length of about 60 km, indicate the presence of two distinct layers over the complete surveying area: (i) a thawed layer at the surface, and (ii) a frozen layer below. In a first interpretation step, we establish a geophysical classification by considering the geophysical signatures of both layers. We use sedimentological information from core logs to relate the geophysical classes to sediment types. This analysis reveals internal structures of Orkhon River sediments, such as channels and floodplain sediments. We also distinguish alluvial fan deposits and

  12. Investigations on the on-line determination of metals in air flows by capacitively coupled microwave plasma atomic emission spectrometry

    NASA Astrophysics Data System (ADS)

    Seelig, M.; Broekaert, J. A. C.

    2001-09-01

    Plasma optical emission spectrometry with a capacitively coupled microwave plasma (CMP) operated with air has been investigated with respect to its possibilities for real-time environmental monitoring of combustion processes. The unique feature is the possibility to operate the CMP with air as working gas, as is usually the case in exhaust gases of combustion processes. The CMP also is shown to be stable in the presence of large amounts of water and CO 2, which makes this source ideally suitable for this purpose. The detection limits obtained for the environmentally relevant elements Cd, Co, Cr, Fe, Mg, Ni and Pb show the possibility to monitor directly heavy metals in air in an on-line mode and down to the 2-160-μg m -3 level. These detection limits are generally lower than the threshold limit values of the 'Federal Law for Immission Protection' in Germany in the gaseous effluents of industrial plants. In order to investigate the influence of the water loading (32-222 g m -3) on the detection limits a comparison of results obtained with three different nebulizers (Légère nebulizer, hydraulic high-pressure nebulizer and ultrasonic nebulizer) was made, with which aerosols with different water loading are entered into the plasma. For the hydraulic high-pressure nebulizer and the ultrasonic nebulizer no desolvation unit was found to be necessary. It was shown that especially for elements with lines having high excitation energy (Cd) or for which ion lines are used (Mg II) the increase in water loading deteriorates the detection limits. The rotational temperatures ( Trot) and excitation temperatures ( Texe) in the case of different amounts of water are of the order of 3700-4900 K and 4700-7100 K, respectively. The temperatures show that changes in the geometry and temperature distribution in the case of Trot but also the values of Texe themselves are responsible for this increase in detection limits. Furthermore, different amounts of CO 2 mixed to the working gas (3

  13. Langmuir probe diagnostics of electron energy distributions with optical emission spectroscopy in capacitively coupled rf discharge in nitrogen

    SciTech Connect

    Abdel-Fattah, E.; Bazavan, M.; Sugai, H.

    2011-12-01

    Measurements with a rf compensated Langmuir probe and optical emission spectroscopy are carried out in capacitively coupled rf (13.56 MHz) pure nitrogen N{sub 2} discharges at fixed rf voltage over a wide range of pressure, 30 to 400 mTorr. The electron energy probability function (EEPF) measured below 100 mTorr resembles a bi-Maxwellian-type distribution. At pressure range of 100-200 mTorr, the EEPF has non-Maxwellian distribution with a ''dip'' near 4.5 eV. At the highest pressure of 400 mTorr, the EEPF evolves into a Druyvestein-like distribution and the ''dip'' disappears. The electron density significantly decreases with increase in the N{sub 2} pressure. On the other hand, the electron temperatures gradually decrease with an increase in N{sub 2} pressure, reaching minimum at 150 mTorr, beyond which it abruptly increases. Such evolution of the EEPFs shape with gas pressure has been discussed in terms of non-local electron kinetics and heating mode transition. The emission intensities of nitrogen (0-0) band of second positive system at 337.1 nm and (0-0) band of first negative systems at 391.4 nm are used to determine the dependence of their radiative states N{sub 2}(C{sup 3}{Pi}{sub u}) and N{sub 2}{sup +}(B{sup 2}{Sigma}{sub u}{sup +}) with nitrogen pressure. It is observed that the pressure influences the radiative states differently owing to their different populating mechanisms. The vibrational temperature T{sub {nu}ib} and rotational temperature T{sub rot} are measured for the sequence ({Delta}{nu}=-2) of N{sub 2} second positive system (C{sup 3}{Pi}{yields}B{sup 3}{Pi}{sub g}) using the method of comparing the measured and calculated spectra with a chi-squared minimization procedure. It was found that both T{sub {nu}ib} and T{sub rot} have similar dependences with N{sub 2} pressure; peaked at 100 mTorr beyond which it monotonically decreases with increase in the N{sub 2} pressure. The correlation between the observed maximum value of T{sub {nu}ib} around

  14. Effect of inductive and capacitive coupling on the current-voltage characteristic and electromagnetic radiation from a system of Josephson junctions

    NASA Astrophysics Data System (ADS)

    Rahmonov, I. R.; Shukrinov, Yu. M.; Atanasova, P. Kh.; Zemlyanaya, E. V.; Bashashin, M. V.

    2017-01-01

    We have studied the current-voltage characteristic of a system of long Josephson junctions taking into account the inductive and capacitive coupling. The dependence of the average time derivative of the phase difference on the bias current and spatiotemporal dependences of the phase difference and magnetic field in each junction are considered. The possibility of branching of the current-voltage characteristic in the region of zero field step, which is associated with different numbers of fluxons in individual Josephson junctions, is demonstrated. The current-voltage characteristic of the system of Josephson junctions is compared with the case of a single junction, and it is shown that the observed branching is due to coupling between the junctions. The intensity of electromagnetic radiation associated with motion of fluxons is calculated, and the effect of coupling between junctions on the radiation power is analyzed.

  15. Application of low pressure capacitively coupled rf hydrogen plasma for low temperature reduction of iron clusters in structure of fe-pillared materials

    NASA Astrophysics Data System (ADS)

    Starshinova, V. L.; Gorelysheva, V. E.; Shinka Jr., A. A., rev; Gnevashev, S. G.; Kulevtsov, G. N.; Shinkarev, A. A.

    2017-01-01

    The unique properties of pillared materials determine their use in catalysis, purification and separation. The paper studies the reduction of composite catalysts, Fe-pillared materials. The authors compare their reduction in low temperature capacitively coupled RF hydrogen discharge of low pressure to their conventional direct hydrogen reduction in a tubular muffle furnace. X-ray diffraction analysis was used to characterize the iron-bearing phases. The results show that the reduction of iron hydro/oxide clusters associated with an aluminosilicate matrix to metallic iron is very challenging due to the degree of the pore space availability for hydrogen.

  16. The influence of the secondary electron induced asymmetry on the electrical asymmetry effect in capacitively coupled plasmas

    SciTech Connect

    Korolov, Ihor; Derzsi, Aranka; Donkó, Zoltán; Schulze, Julian

    2013-08-05

    In geometrically symmetric capacitive radio-frequency plasmas driven by two consecutive harmonics, a dc self-bias can be generated as a function of the phase shift between the driving frequencies via the Electrical Asymmetry Effect (EAE). Recently, the Secondary Electron Asymmetry Effect (SEAE) was discovered (Lafleur et al., J. Phys. D: Appl. Phys. 46, 135201 (2013)): unequal secondary electron emission coefficients at both electrodes were found to induce an asymmetry in single-frequency capacitive plasmas. Here, we investigate the simultaneous presence of both effects, i.e., a dual-frequency plasma driven by two consecutive harmonics with different electrode materials. We find that the superposition of the EAE and the SEAE is generally non-linear, i.e., the asymmetries generated by each individual effect do not simply add up at all phases. The control ranges of the dc self-bias and the mean ion energy can be enlarged, if both effects are combined.

  17. 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.

  18. Capacitively coupled contactless conductivity detection as an alternative detection mode in CE for the analysis of kanamycin sulphate and its related substances.

    PubMed

    El-Attug, Mohamed N; Adams, Erwin; Hoogmartens, Jos; Van Schepdael, Ann

    2011-09-01

    A method was developed to determine simultaneously kanamycin, its related substances and sulphate in kanamycin sulphate using capacitively coupled contactless conductivity detection. Kanamycin is an aminoglycoside antibiotic that lacks a strong UV-absorbing chromophore. Due to its physicochemical properties, CE in combination with capacitively coupled contactless conductivity detection was chosen. The separation method uses a BGE composed of 40 mM 2-(N-morpholino)ethanesulphonic acid monohydrate and 40 mM L-histidine, pH 6.35. A 0.6 mM N-cetyltrimethyl ammonium bromide (CTAB) solution was added as electroosmotic flow modifier in a concentration below the critical micellar concentration (CMC). Ammonium acetate 50 mg/L was used as internal standard. In total, 30 kV was applied in reverse polarity on a fused-silica capillary (65/41 cm; 75 μm id). The optimized separation was obtained in less than 6 min with good linearity (R(2)=0.9999) for kanamycin. It shows a good precision expressed as RSD on the relative peak areas equal to 0.3 and 1.1% for intra-day and inter-day precision, respectively. The LOD and LOQ are 0.7 and 2.3 mg/L, respectively. Similarly, for sulphate, a good linearity (R(2)=0.9996) and precision (RSD 0.4 and 0.6% for intra-day and inter-day, respectively) were obtained.

  19. 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.

  20. keV-energy x-rays from a low-pressure, low-power, low-field, capacitively coupled 27-MHz hydrogen plasma source

    NASA Astrophysics Data System (ADS)

    Jandovitz, Peter; Swanson, Charles; Matteucci, Jackson; Cohen, S. A.

    2015-11-01

    We report on the unexpected observation of 0.9-5 keV x-rays coming from a cool (bulk Te ~ 4 eV), tenuous (ne ~1010 cm-3) 5-cm-diameter hydrogen plasma column generated in a tandem high-mirror-ratio mirror machine by an external, capacitively-coupled RF (27 MHz) antenna operating at low power, 20-500 W. The x-rays, measured with an Amptek XR-100CR detector, are evidence of energetic electrons that have not been seen previously in experiment or theory in similar plasmas. In the neutral H2 gas pressure range of 0.4 to 1.5 mT, the x-ray emissivity increased with decreasing pressure. No x-rays were observed when operating with argon (or 30/70 argon/hydrogen mixtures) at similar powers and pressures in either capacitively-coupled or helicon modes. X-ray count rate smoothly increased as mirror ratio increased and reached a broad maximum near 80 G, central field. Time-dependent emissivity with pulsed RF power and spatial profiles over a limited axial range have been measured. Possible heating mechanisms, including Fermi acceleration, cyclotron resonance, double layers, and sheaths, are being considered. This work was supported by DOE contract DE-AC02-09CH11466.

  1. Spatial distribution of nonemissive metastables in a two-frequency capacitively coupled plasma in Ar by using a pair of optical emission lines

    SciTech Connect

    Ohba, Tomihito; Makabe, Toshiaki

    2010-03-15

    When a pair of short- and long-lived excited molecules are coupled with an upper radiative state, it will be possible to derive the number density of the long-lived species from the optical emission spectroscopy of upper-level short-lived species by careful selection of the pair. Two-dimensional density distributions of the long-lived metastable state Ar(1s{sub 5}) and that of the short-lived excited state Ar(2p{sub 2}) are observed and compared in the time-averaged form, using a computerized tomography technique of the emissions from a pair of optical transitions in a two-frequency capacitively coupled plasma in pure Ar.

  2. Extraction of the gate capacitance coupling coefficient in floating gate non-volatile memories: Statistical study of the effect of mismatching between floating gate memory and reference transistor in dummy cell extraction methods

    NASA Astrophysics Data System (ADS)

    Rafhay, Quentin; Beug, M. Florian; Duane, Russell

    2007-04-01

    This paper presents an experimental comparison of dummy cell extraction methods of the gate capacitance coupling coefficient for floating gate non-volatile memory structures from different geometries and technologies. These results show the significant influence of mismatching floating gate devices and reference transistors on the extraction of the gate capacitance coupling coefficient. In addition, it demonstrates the accuracy of the new bulk bias dummy cell extraction method and the importance of the β function, introduced recently in [Duane R, Beug F, Mathewson A. Novel capacitance coupling coefficient measurement methodology for floating gate non-volatile memory devices. IEEE Electr Dev Lett 2005;26(7):507-9], to determine matching pairs of floating gate memory and reference transistor.

  3. 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

  4. 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. Copyright © 2015 Elsevier B.V. All rights reserved.

  5. Threshold voltage control for organic thin-film transistors using a tri-gate structure with capacitive coupling

    NASA Astrophysics Data System (ADS)

    Lee, Sunghoon; Yokota, Tomoyuki; Someya, Takao

    2017-04-01

    We demonstrate a novel transistor structure comprising three gate electrodes: top gate, floating gate, and bottom gate. The floating gate electrode is located between the top and bottom gates. The tri-gate structure enables post-fabrication V TH control by sharing the dominance of both the top and bottom gates in the floating gate without affecting the semiconductor layer. V TH is controlled for a wide range of over 3.5 V, and the experimental results of V TH controllability coincide strongly with the theoretical analysis. The capacitance ratio between either the top or bottom gate and the floating gate is investigated, and a linear relation of V TH control is achieved without changing other transistor parameters such as the subthreshold swing, on/off ratio, or carrier mobility.

  6. Capacitive transducers

    NASA Technical Reports Server (NTRS)

    Lucifredi, A. L.

    1970-01-01

    The theory, applications, and possible structural designs of capacitive transducers are presented. Emphasis is placed on the circuits used in connection with the sensors, such as AM, FM, resonant circuits, mode circuits, direct current circuits, and special circuits. Some criteria for selection of a design or the purchase of a commercial device are given.

  7. 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.

  8. Portable integrated capillary-electrophoresis system using disposable polymer chips with capacitively coupled contactless conductivity detection for on-site analysis of foodstuff

    NASA Astrophysics Data System (ADS)

    Gärtner, Claudia; Hoffmann, Werner; Demattio, Horst; Clemens, Thomas; Klotz, Matthias; Klemm, Richard; Becker, Holger

    2009-05-01

    We present a compact portable chip-based capillary electrophoresis system that employs capacitively coupled contactless conductivity detection (C4D) operating at 4 MHz as an alternative detection method compared to the commonly used optical detection based on laser-induced fluorescence. Emphasis was put on system integration and industrial manufacturing technologies for the system. Therefore, the disposable chip for this system is fabricated out of PMMA using injection molding; the electrodes are screen-printed or thin-film electrodes. The system is designed for the measurement of small ionic species like Li+, Na+, K+, SO42- or NO3- typically present in foods like milk and mineral water as well as acids e.g. in wine.

  9. Spatially resolved measurements of ion density and electron temperature in a dual-frequency capacitively coupled plasma by complete floating double probe technique

    SciTech Connect

    Jiang Xiangzhan; Liu Yongxin; Yang Shuo; Lu Wenqi; Bi Zhenhua; Li Xiaosong; Wang Younian

    2011-01-15

    Spatially resolved measurements of the ion density and electron temperature in a dual-frequency capacitively coupled Ar discharge plasma are performed with a newly developed complete floating double probe. Axial and radial distributions of the ion density and electron temperature under various high-frequency (HF) power and gas pressure were studied in detail. Both the ion density and the electron temperature increased with increasing HF power. With increasing gas pressure from 1.3 to 9.3 Pa, the radial profile of ion density below the driven electrode experienced a change from ''bimodal'' to ''unimodal'' shape, with better uniformity being achieved at the optimal pressure of about 5 Pa. In addition, changing the axial profile of ion density was also observed with the peak shift toward the powered electrode at higher pressures. The measured results showed satisfying consistency with that of improved two dimensional fluid simulations.

  10. The effect of secondary electrons on the separate control of ion energy and flux in dual-frequency capacitively coupled radio frequency discharges

    SciTech Connect

    Donko, Z.; Hartmann, P.; Korolov, I.; Schulze, J.; Czarnetzki, U.; Schuengel, E.

    2010-08-23

    Dual-frequency capacitive discharges are used to separately control the mean ion energy, {epsilon}{sub ion}, and flux, {Gamma}{sub ion}, at the electrodes. We study the effect of secondary electrons on this separate control in argon discharges driven at 2+27 MHz at different pressures using Particle in Cell simulations. For secondary yield {gamma}{approx_equal}0, {Gamma}{sub ion} decreases as a function of the low frequency voltage amplitude due to the frequency coupling, while it increases at high {gamma} due to the effective multiplication of secondary electrons inside the sheaths. Therefore, separate control is strongly limited. {epsilon}{sub ion} increases with {gamma}, which might allow an in situ determination of {gamma}-coefficients.

  11. Numerical results for the Ar and CF{sub 4} mixture gas in a dual frequency capacitively coupled plasma using a hybrid model

    SciTech Connect

    Bi Zhenhua; Dai Zhongling; Xu Xiang; Li Zhicheng; Wang Younian

    2009-04-15

    A one dimensional hybrid model has been proposed to study the Ar and CF{sub 4} mixture gas in a dual-frequency (DF) capacitively coupled plasma. To achieve the more precise spatiotemporal distributions of the electric field and ions flux, the ion momentum equations are adopted instead of the drift-diffusion model with the effective electric field approximation. By adjusting DF sources, the evolutions of ions densities, ion energy distributions, and ion angular distributions are obtained and the modulation effects are discussed. Finally, the comparison between the simulation and experimental result shows that the hybrid model could qualitatively describe the characteristic of the mixtures in less time, which will be more promising in two dimensional and three dimensional simulations.

  12. Dual frequency mid-gap capacitively coupled plasma (m-CCP) for conventional and DSA patterning at 10nm node and beyond

    NASA Astrophysics Data System (ADS)

    Mohanty, Nihar; Ko, Akiteru; Cole, Christopher; Rastogi, Vinayak; Kumar, Kaushik; Schmid, Gerard; Farrell, Richard; Ryan, Todd; Hosler, Erik; Xu, Ji; Preil, Moshe

    2014-03-01

    In this paper, we demonstrate the unique advantage of dual-frequency mid-gap capacitively coupled plasma (m-CCP) in advanced node patterning process with regard to etch rate / depth uniformity and critical dimension (CD) control in conjunction with wider process window for aspect ratio dependent & microloading effects. Unlike the non-planar plasma sources, the simple design of the mid-gap CCPs enables both metal and non-metal hard-mask based patterning, which provides essential flexibility for conventional and DSA patterning. We present data on both, the conventional multi patterning as well as DSA patterning for trenches / fins and holes. Rigorous CD control and CDU is shown to be crucial for multi patterning as they lead to undesirable odd-even delta and pitch walking. For DSA patterning, co-optimized Ne / Vdc of the dual frequency CCPs would be demonstrated to be advantageous for higher organic-to-organic selectivity during co-polymer etching.

  13. Ultra-fast determination of caffeine, dipyrone, and acetylsalicylic acid by capillary electrophoresis with capacitively coupled contactless conductivity detection and identification of degradation products.

    PubMed

    Marra, Mariana Cardoso; Cunha, Rafael Rodrigues; Vidal, Denis Tadeu Rajh; Munoz, Rodrigo Alejandro Abarza; do Lago, Claudimir Lucio; Richter, Eduardo Mathias

    2014-01-31

    Capillary electrophoresis with capacitively coupled contactless conductivity detection (CE-C(4)D) was used for fast, simultaneous determination of dipyrone (DIP), caffeine (CAF), and acetylsalicylic acid (ASA). In the same run and in less than 1min, the degradation products from DIP and ASA were also detected. In addition, the usage of the CE-C(4)D system allowed, for the first time, the detection of methylamine as a degradation product of DIP. Capillary electrophoresis with electrospray mass spectrometry experiments were carried out in order to confirm the formation of methylamine. The limits of detection by CE-C(4)D were 5, 5, and 6μmolL(-1) for CAF, DIP, and ASA, respectively. The proposed method was applied to the analysis of these compounds in pharmaceutical formulations with similar results to those achieved by HPLC (p<0.05).

  14. 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.

  15. Time-resolved ion flux, electron temperature and plasma density measurements in a pulsed Ar plasma using a capacitively coupled planar probe

    NASA Astrophysics Data System (ADS)

    Darnon, Maxime; Cunge, Gilles; Braithwaite, Nicholas St. J.

    2014-04-01

    The resurgence of industrial interest in pulsed radiofrequency plasmas for etching applications highlights the fact that these plasmas are much less well characterized than their continuous wave counterparts. A capacitively coupled planar probe is used to determine the time variations of the ion flux, electron temperature (of the high-energy tail of the electron energy distribution function) and plasma density. For a pulsing frequency of 1 kHz or higher, the plasma never reaches a steady state during the on-time and is not fully extinguished during the off-time. The drop of plasma density during the off-time leads to an overshoot in the electron temperature at the beginning of each pulse, particularly at low frequencies, in good agreement with modeling results from the literature.

  16. Solcoseryl, a tissue respiration stimulating agent, significantly enhances the effect of capacitively coupled electric field on the promotion of bone formation around dental implants.

    PubMed

    Ochi, Morio; Wang, Pao-Li; Ohura, Kiyoshi; Takashima, Shigenori; Kagami, Hiroyuki; Hirose, Yukito; Kaku, Tohru; Sakaguchi, Kunihiko

    2003-06-01

    In the present study we examined the combined effect of application of a capacitively coupled electric field (CCEF) and the tissue respiration stimulating agent, Solcoseryl, on the promotion of bone formation around dental implants histologically and mechanically. After a dental implant was inserted into each femur of Japanese white rabbits, Solcoseryl (2 ml/kg) was administered intravenously in the ear vein and a CCEF was applied for 4 h per day for 14 days. The degree of bone formation on microscopic observation, bone contact ratio, bone surface area ratio, and the level of removal torque of the implant in the Solcoseryl- and CCEF-treated group were significantly higher than the respective value in the control group, which had not been treated with Solcoseryl nor CCEF. Thus, the combination of CCEF stimulation and Solcoseryl effectively promoted the formation of new bone. It is suggested that the clinical use of a combination of CCEF stimulation and Solcoseryl for dental implants promotes osseointegration.

  17. Trace determination of Hg together with As, Sb, Se by miniaturized optical emission spectrometry integrated with chemical vapor generation and capacitively coupled argon microwave miniplasma discharge

    NASA Astrophysics Data System (ADS)

    Matusiewicz, Henryk; Ślachciński, Mariusz

    2017-07-01

    A miniaturized optical emission spectrometer (OES) with capacitively coupled argon microwave microplasma (μCMP) as and excitation source and chemical vapor generation (CVG) for sample introduction was constructed for the determination of trace Hg, As, Sb and Se. The applied method enabled simultaneous determination of hydride-forming elements (As, Sb, Se) and volatile Hg. Mercury cold vapor and the hydride volatile species of As, Sb and Se were generated when standard or sample solutions were separated from the liquid phase for transport to the capacitively coupled microwave microplasma and detection of their atomic emission. A univariate approach and the simplex optimization procedure were used to achieve optimized conditions and derive analytical figures of merit. The experimental concentration detection limits (LODs) for simultaneous determination, calculated as the concentration giving a signal equal to three times of the standard deviation of the blank (LOD, 3σblank criterion, peak height) were 3.0, 1.4, 1.5 and 3.8 ng mL- 1 for Hg, As, Sb and Se, respectively. The method was validated by the analysis of three Certified Reference Materials (NIST 2711, NRCC DOLT-2, NIST 1643e) of different matrix composition and by the standard addition technique. The method offers relatively good precision (RSD ranged from 5% to 8%) for microsampling (200 μL) analysis. The measured of contents of elements in certified reference materials were in good agreement with the certified values (Hg 1.99-6.25 μg g- 1, As 16.6-105 μg g- 1, Sb 19.4-56.88 μg g- 1, Se 1.52-11.68 μg g- 1), according to the Student t-test, for a confidence level of 95%.

  18. Numerical investigation of ion energy distribution and ion angle distribution in a dual-frequency capacitively coupled plasma with a hybrid model

    SciTech Connect

    Wang Shuai; Xu Xiang; Wang Younian

    2007-11-15

    A one-dimensional hybrid model is developed to study the characteristics of energy and angular distributions of the ions and fast neutrals impinging on the rf-biased electrode in a dual-frequency capacitively coupled Ar discharge. The hybrid model consists of a fluid model that determines the spatiotemporal evolution of the discharge, and a Monte-Carlo model that, including the electron-neutral, ion-neutral, and fast neutral-neutral collisions, predicts the energy and angular distributions of the ions and fast neutrals on the rf-biased electrode. The influence of pressure, voltage amplitude, and frequencies of the two rf sources on the energy and angular distributions is discussed. The ion energy distributions (IEDs) appear to have multiple peaks in the dual-frequency capacitively coupled rf discharge rather than bimodal shape in a conventional single-frequency rf discharge. The ion angle distributions (IADs) have a significant peak at a small angle, and most ions strike to the process surface with the angle less than 4 deg. With the increase of the pressure, the maximum energy of IEDs and the peaks of IADs decrease. The structures of IEDs are controlled mainly by the voltage and frequency applied to the two rf sources. By decreasing the frequency or adding the voltage applied to the low-frequency (LF) source, the width of IEDs and the maximum energy increase. More ions strike to the electrode with a small angle by increasing either the voltage of LF source or the frequency of high-frequency source. The energy and angular distributions of the fast neutrals are correlative with those of the ions. Compared with the ions, the fast neutrals have a much lower energy and the scattering effect becomes more prominent.

  19. Optimization of the electrical asymmetry effect in dual-frequency capacitively coupled radio frequency discharges: Experiment, simulation, and model

    SciTech Connect

    Schulze, J.; Schuengel, E.; Czarnetzki, U.; Donko, Z.

    2009-09-15

    An electrical asymmetry in capacitive rf discharges with a symmetrical electrode configuration can be induced by driving the discharge with a fundamental frequency and its second harmonic. For equal amplitudes of the applied voltage waveforms, it has been demonstrated by modeling, simulation, and experiments that this electrical asymmetry effect (EAE) leads to the generation of a variable dc self-bias that depends almost linearly on the phase angle between the driving voltage signals. Here, the dependence of the dc self-bias generated by the EAE on the choice of the voltage amplitudes, i.e., the ratio A of high to low frequency amplitude, is investigated experimentally as well as by using an analytical model and a particle-in-cell simulation. It is found that (i) the strongest electrical asymmetry is induced for A<1 at pressures ranging from 6 to 100 Pa and that (ii) around this optimum voltage ratio the dc self-bias normalized to the sum of both voltage amplitudes is fairly insensitive to changes of A. Thus, by choosing the optimum voltage ratio, the EAE is optimized: The ion energy can be changed over a broader energy range and a high degree of process stability with respect to small changes in the applied voltages is expected.

  20. 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.

  1. 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.

  2. Analytical capability of a medium power capacitively coupled plasma for the multielemental determination in multimineral/multivitamin preparations by atomic emission spectrometry.

    PubMed

    Frentiu, Tiberiu; Ponta, Michaela; Darvasi, Eugen; Frentiu, Maria; Cordos, Emil

    2012-10-15

    A method for multielemental (Ca, Cr, Cu, Fe, K, Mg, Mn, Na, P and Zn) determination in multimineral/multivitamins by atomic emission spectrometry in a medium power radiofrequency capacitively coupled plasma (275 W) and low Ar consumption (0.4 L min(-1)) is proposed. Determinations were performed on commercially available tablets and a standard reference material after acidic high-pressure microwave assisted digestion and using the standard additions procedure. The detection limits (mg g(-1)) were in the range 0.003 (Na)-1.5 (P) and were not depreciated by the non-spectral interference of mineral matrices of K, Ca, Mg and Na excepting Zn and P. Found concentrations corresponded generally to the labelled contents with recovery in the range of 90-107% and 1.0-13.0% repeatability. The proposed technique could be an advantageous alternative to the more expensive inductively coupled plasma atomic emission spectrometry in the quality control of multimineral/multivitamin preparations. Copyright © 2012 Elsevier Ltd. All rights reserved.

  3. Discharge characteristics and non-spectral interferences on the emission of ca species in a medium power radiofrequency capacitively coupled plasma source.

    PubMed

    Frentiu, Tiberiu; Ponta, Michaela; Darvasi, Eugen; Frentiu, Maria; Cordos, Emil A

    2010-03-01

    Non-spectral interference of easily ionized elements (EIEs) as chlorides and Al as AlCl3 and Al(NO3)3 on the emission of Ca II 393.367 nm, Ca I 422.673 nm, CaOH 554 nm and 622 nm were studied in a medium power radiofrequency capacitively coupled Ar plasma (275 W, 27.12 MHz) with single (SRTrfCCP) and double ring electrode (DRTrfCCP). The mechanisms of interferences were explained based on the matrix energy demand (MED) supposing the local thermal equilibrium (LTE) in plasma, emphasizing also processes contrasting with this model. Matrix effects were found to be dependent on the coupling geometry of the rf power to the torch, observation height, emitting Ca species and EIEs matrix nature but independent from Al as regards its salt origin. The magnitude of the matrix effects was correlated with the electron number density and the discharge temperature. The optimization of the observation height and use of the DRT geometry allowed the reduction of EIEs and Al matrix effects on the emission of Ca species compared to SRT. The best Ca detection limits in SRTrfCCP were at CaOH 622 nm (106-450 ng ml-1), while in DRTrfCCP at Ca I 422.673 nm (92-145 ng ml-1).

  4. 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.

  5. Capacitively coupled microplasma for on-column detection of chromatographically separated inorganic gases by optical emission spectrometry.

    PubMed

    Guchardi, Renato; Hauser, Peter C

    2004-04-16

    Two tubular electrodes placed on a capillary tubing are used to couple an electrical ac field of high voltage (20 kV) but low frequency (20 kHz) and about 8 W power inside for generation of the plasma. The emitted radiation is passed to a spectrometer via an optical fibre butted to the side of the capillary. The excitation temperature of the plasma determined from helium emission lines is about 4000 K. It was found possible to detect oxygen from its emission at 777 and 845 nm, hydrogen at 656 nm and sulfur containing species from emission at 923 nm. The carbon-containing species CH4, CO, and CO2 could be determined from an emission band at 385 nm due to CN. Detection limits in the range between about 1 and 10 ng were obtained using a miniature diode array spectrometer.

  6. Ion-implanted capacitively coupled silicon strip detectors with integrated polysilicon bias resistors processed on a 100 mm wafer

    NASA Astrophysics Data System (ADS)

    Hietanen, Iiro; Lindgren, Jukka; Orava, Risto; Tuuva, Tuure; Voutilainen, Martti; Brenner, Richard; Andersson, Mikael; Leinonen, Kari; Ronkainen, Hannu

    1991-12-01

    Double-sided silicon strip detectors with integrated coupling capacitors and polysilicon resistors have been processed on a 100 mm wafer. A detector with an active area of 19 × 19 mm 2 was connected to LSI readout electronics and tested. The strip pitch of the detector is 25 μm on the p-side and 50 μm on the n-side. The readout pitch is 50 μm on both sides. The number of readout strips is 774 and the total number of strips is 1161. On the p-side a signal-to-noise of 35 has been measured using a 90Sr β-source. The n-side has been studied using a laser.

  7. Absolute CF2 density and gas temperature measurements by absorption spectroscopy in dual-frequency capacitively coupled CF4/Ar plasmas

    NASA Astrophysics Data System (ADS)

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

    2014-10-01

    Broadband ultraviolet absorption spectroscopy has been used to determine the CF2 radical density in dual-frequency capacitively coupled CF4/Ar plasmas, using the CF2 A ˜ 1 B 1 ← X ˜ 1 A 1 system of absorption spectrum. The rotational temperature of ground state CF2 and excited state CF was also estimated by using A ˜ 1 B 1 ← X ˜ 1 A 1 system and B 2 Δ - X 2 Π system, respectively. The translational gas temperature was deduced from the Doppler width of the Ar*(3P2) and Ar*(3P0) 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 CF2, and about 200 K higher than the translational gas temperatures. The dependences of the radical CF2 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 CF2 radical and the gas heating mechanisms have also been discussed.

  8. 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.

  9. One-dimensional hybrid simulation of the electrical asymmetry effect caused by the fourth-order harmonic in dual-frequency capacitively coupled plasma

    NASA Astrophysics Data System (ADS)

    Wang, Shuai; Long, Hai-Feng; Bi, Zhen-Hua; Jiang, Wei; Xu, Xiang; Wang, You-Nian

    2016-11-01

    A one-dimensional hybrid model was developed to study the electrical asymmetry effect (EAE) caused by the fourth-order harmonic in a dual-frequency capacitively coupled Ar plasma. The self-bias voltage caused by the fourth-order frequency changes periodically with the phase angle, and the cycle of self-bias with the phase angle is π/2, which is half of that in the second-order case. The influence of the phase angle between the fundamental and its fourth-order frequency on the ion density profiles and the ion energy distributions (IEDs) were studied. Both the ion density profile and the IEDs can be controlled by the phase angle, which provides a convenient way to adjust the sheath characters without changing the main discharge parameters. Project supported by the National Natural Science Foundation of China (Grant Nos. 11305032, 11305028, 11375163, and 11275039) and the Scientific Foundation of Ministry of Education of China (Grant No. N130405008).

  10. 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.

  11. 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.

  12. Two Dimensional Particle-in-cell/Monte Carlo (PIC/MC) Simulation of Radio Frequency Capacitively Coupled Plasmas with a Dielectric Side Wall Boundary

    NASA Astrophysics Data System (ADS)

    Liu, Yue; Booth, Jean-Paul; Chabert, Pascal; cold plasma Team, LPP Team

    2016-09-01

    The majority of previous two dimensional (usually fluid) simulations of radio frequency capacitively coupled plasmas have focused on geometrically-asymmetric reactors (with a much larger grounded electrode than power electrode), which produces a strong dc self-bias. However, a commonly-used geometry comprises electrodes of equal area surrounded by a dielectric side wall, but this has not been widely simulated. We have developed a two dimensional (Cartesian) PIC/MC code based on the work of Hongyu Wang, Wei Jiang and Younian Wang, to simulate argon plasmas in this kind of chamber. Even using a thick dielectric, a peak in plasma density and electron power deposition is adjacent to the dielectric. The profiles of the electron and ion fluxes show that the period-averaged currents to the powered electrode are not locally balanced; the electron flux peaks closer to the dielectric edge, before dropping sharply. Finally, the effect of the dielectric thickness on the surface charge distribution and the angular distributions of ions arriving at boundaries is examined. This work is supported by China Scholarship Council.

  13. A low-cost method for determination of calcium carbonate in cement by membraneless vaporization with capacitively coupled contactless conductivity detection.

    PubMed

    Sereenonchai, Kamonthip; Teerasong, Saowapak; Chan-Eam, Sumonmarn; Saetear, Phoonthawee; Choengchan, Nathawut; Uraisin, Kanchana; Amornthammarong, Natchanon; Motomizu, Shoji; Nacapricha, Duangjai

    2010-05-15

    This work presents a flow analysis method for direct quantitation of calcium carbonate in cement without pretreatment of the sample. The method is based on online vaporization of CO(2) gas following acidification of the sample inside a small chamber that has a flow of acceptor solution passing around it. Solubilization of the CO(2) gas into the acceptor stream changes the conductivity of the acceptor solution causing an increase of signal at the capacitively coupled contactless conductivity detection (C(4)D) placed at the outlet of the vaporization chamber. This chamber is an adaption from previous work reported on 'membraneless vaporization' (MBL-VP). The method can be used in the quality control of production of mixed cement. These cement materials usually have calcium carbonate contents at high concentration range (e.g., 33-99% (w/w) CaCO(3)). Analysis of samples by this method is direct and convenient as it requires no sample pretreatment. The method is low-cost with satisfactory accuracy and acceptable precision.

  14. 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.

  15. Effect of driving frequency on the electron energy distribution function and electron-sheath interaction in a low pressure capacitively coupled plasma

    NASA Astrophysics Data System (ADS)

    Sharma, S.; Sirse, N.; Kaw, P. K.; Turner, M. M.; Ellingboe, A. R.

    2016-11-01

    By using a self-consistent particle-in-cell simulation, we investigated the effect of driving frequency (27.12-70 MHz) on the electron energy distribution function (EEDF) and electron-sheath interaction in a low pressure (5 mTorr) capacitively coupled Ar discharge for a fixed discharge voltage. We observed a mode transition with driving frequency, changing the shape of EEDF from a strongly bi-Maxwellian at a driving frequency of 27.12 MHz to a convex type distribution at an intermediate frequency, 50 MHz, and finally becomes a weak bi-Maxwellian at a higher driving frequency, i.e., above 50 MHz. The transition is caused by the electric field transients, which is of the order of electron plasma frequency caused by the energetic "beams" of electrons ejected from near the sheath edge. Below the transition frequency, 50 MHz, these high energy electrons redistribute their energy with low energy electrons, thereby increasing the effective electron temperature in the plasma, whereas the plasma density remains nearly constant. Above the transition frequency, high-energy electrons are confined between opposite sheaths, which increase the ionization probability and therefore the plasma density increases drastically.

  16. Analysis of intermediate pressure SiH4/He capacitively coupled plasma for deposition of an amorphous hydrogenated silicon film in consideration of thermal diffusion effects

    NASA Astrophysics Data System (ADS)

    Kim, Ho Jun; Lee, Hae June

    2017-08-01

    To achieve rapid, uniform deposition of an amorphous hydrogenated silicon (a-Si:H) film, a capacitively coupled plasma (CCP) is often used at an intermediate pressure (>100 Pa), with a silane (SiH4)-based mixture. At these pressures, heavy particle interactions (such as ion-ion, ion-neutral, and neutral-neutral reactions) contribute significantly to the formation of precursor radicals. By adding a consideration of the thermal diffusion effects to the neutral transport equation, the chemical processes have been numerically analyzed with variation in the number fraction of SiH4 and electrode spacing using a two-dimensional fluid model of radio frequency discharges in a cylindrically symmetric CCP reactor. The non-uniformity of the deposition rate profiles increases consistently as electrode spacing increases, although the non-uniformity of the plasma parameters decreases with the increase of electrode spacing. The simulated deposition rate profiles match well with the experimental data for the change of electrode spacing. Based on the validation of our model, we propose predictive designs to potentially improve the reactor and process by modifying the thermal and electrical surface conditions.

  17. 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.

  18. A simple method for determination of erythritol, maltitol, xylitol, and sorbitol in sugar-free chocolates by capillary electrophoresis with capacitively coupled contactless conductivity detection.

    PubMed

    Coelho, Aline Guadalupe; de Jesus, Dosil Pereira

    2016-11-01

    In this work, a novel and simple analytical method using capillary electrophoresis (CE) with capacitively coupled contactless conductivity detection (C(4) D) is proposed for the determination of the polyols erythritol, maltitol, xylitol, and sorbitol in sugar-free chocolate. CE separation of the polyols was achieved in less than 6 min, and it was mediated by the interaction between the polyols and the borate ions in the background electrolyte, forming negatively charged borate esters. The extraction of the polyols from the samples was simply obtained using ultra-pure water and ultrasonic energy. Linearity was assessed by calibration curves that showed R(2) varying from 0.9920 to 0.9976. The LOQs were 12.4, 15.9, 9.0, and 9.0 μg/g for erythritol, maltitol, xylitol, and sorbitol, respectively. The accuracy of the method was evaluated by recovery tests, and the obtained recoveries varied from 70 to 116% with standard deviations ranging from 0.2 to 19%. The CE-C(4) D method was successfully applied for the determination of the studied polyols in commercial samples of sugar-free chocolate. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

  19. Comparison of measurements and particle-in-cell simulations of ion energy distribution functions in a capacitively coupled radio-frequency discharge

    SciTech Connect

    O'Connell, D.; Zorat, R.; Ellingboe, A. R.; Turner, M. M.

    2007-10-15

    The ion dynamics in the high-voltage sheath of a capacitively coupled radio-frequency plasma has been investigated using mass-resolved ion energy analysis in combination with a two-dimensional particle-in-cell (PIC) code. A symmetric confined discharge is designed allowing highly accurate comparisons of measured ion energy distribution functions in high-voltage sheaths with simulation results. Under the conditions investigated, the sheaths are not only collisional, but also chemically complex. This situation is common in applications but rare in laboratory experiments. Excellent agreement has been found for a hydrogen discharge benchmarking the code. Hydrogen is of particular interest since its light mass gives detailed insight into sheath dynamics, and an extensive database of collisional cross sections is available. The H{sub 3}{sup +} ion was found to be the dominant ion in the sheaths and the plasma bulk under most conditions investigated. H{sub 3}{sup +} exhibits the typical saddle-shaped ion energy distribution function indicative of ions created in the plasma bulk and traversing the entire sheath potential. H{sup +} and H{sub 2}{sup +} are predominantly formed through collisions in the high-voltage sheath. H{sub 2}{sup +} ion energy distribution functions show structures resulting from symmetric charge exchange collisions with the background gas. Minor discrepancies between the experimental results and PIC simulations indicate slightly lower plasma densities in the simulation, resulting in larger sheath width.

  20. 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.

  1. Spectroscopic study on rotational and vibrational temperature of N{sub 2} and N{sub 2}{sup +} in dual-frequency capacitively coupled plasma

    SciTech Connect

    Huang Xiaojiang; Xin Yu; Yang Lei; Yuan Quanhua; Ning Zhaoyuan

    2008-11-15

    By using optical emission spectroscopy, the vibrational and rotational temperatures of N{sub 2} and N{sub 2}{sup +} in capacitively coupled plasma (CCP) discharges driven by dual-frequency 41 MHz and 2 MHz are investigated. The vibrational and rotational temperatures are measured based on the N{sub 2}{sup +} first negative system and N{sub 2} second positive system overlapped molecular emission optical spectrum, using the method of comparing the measured and calculated spectra with a least-square procedure. The influence of the rotational and vibrational temperatures with input power of the high frequency (HF) and low frequency (LF) as well as the gas pressure is discussed. It is found that the vibrational or rotational temperatures of N{sub 2} and N{sub 2}{sup +} are decoupled in dual-frequency CCP discharge. The influence of the LF power on N{sub 2}{sup +} rotational and vibrational temperature is much more than that of N{sub 2}, while the influence of HF power is just opposite to the case of LF power. The reason for this is thought to be the variation of electron temperature when applying HF or LF power. Additionally, the increase of gas pressure makes the difference between the vibrational and rotational temperature decrease.

  2. Comparison of measurements and particle-in-cell simulations of ion energy distribution functions in a capacitively coupled radio-frequency discharge

    NASA Astrophysics Data System (ADS)

    O'Connell, D.; Zorat, R.; Ellingboe, A. R.; Turner, M. M.

    2007-10-01

    The ion dynamics in the high-voltage sheath of a capacitively coupled radio-frequency plasma has been investigated using mass-resolved ion energy analysis in combination with a two-dimensional particle-in-cell (PIC) code. A symmetric confined discharge is designed allowing highly accurate comparisons of measured ion energy distribution functions in high-voltage sheaths with simulation results. Under the conditions investigated, the sheaths are not only collisional, but also chemically complex. This situation is common in applications but rare in laboratory experiments. Excellent agreement has been found for a hydrogen discharge benchmarking the code. Hydrogen is of particular interest since its light mass gives detailed insight into sheath dynamics, and an extensive database of collisional cross sections is available. The H3+ ion was found to be the dominant ion in the sheaths and the plasma bulk under most conditions investigated. H3+ exhibits the typical saddle-shaped ion energy distribution function indicative of ions created in the plasma bulk and traversing the entire sheath potential. H+ and H2+ are predominantly formed through collisions in the high-voltage sheath. H2+ ion energy distribution functions show structures resulting from symmetric charge exchange collisions with the background gas. Minor discrepancies between the experimental results and PIC simulations indicate slightly lower plasma densities in the simulation, resulting in larger sheath width.

  3. Development and validation of a capillary electrophoresis method with capacitively coupled contactless conductivity detection (CE-C(4) D) for the analysis of amikacin and its related substances.

    PubMed

    El-Attug, Mohamed Nouri; Adams, Erwin; Van Schepdael, Ann

    2012-09-01

    Amikacin is a semisynthetic aminoglycoside antibiotic derived from kanamycin A that lacks a strong UV absorbing chromophore or fluorophore. Due to the physicochemical properties of amikacin and its related substances, CE in combination with capacitively coupled contactless conductivity detection (CE-C(4) D) was chosen. The optimized separation method uses a BGE composed of 20 mM MES adjusted to pH 6.6 by l-histidine and 0.3 mM CTAB that was added as flow modifier in a concentration below the CMC. Ammonium acetate 20 mg.L(-1) was used as internal standard. 30 kV was applied in reverse polarity on a fused silica capillary (73/48 cm; 75 μm id). The optimized separation was obtained in less than 6 min with good linearity (R(2) = 0.9996) for amikacin base. It shows a good precision expressed as RSD on relative peak areas equal to 0.1 and 0.7% for intraday and interday, respectively. The LOD and LOQ are 0.5 mg.L(-1) and 1.7 mg.L(-1) , respectively.

  4. Study of a dual frequency capacitively coupled rf discharge in the background of multi-component plasma and its validation by a simple analytical sheath model

    NASA Astrophysics Data System (ADS)

    Bhuyan, Heman; Saikia, Partha; Favre, Mario; Wyndham, Edmundo; Veloso, Felipe

    2016-10-01

    The behavior of a phase-locked dual frequency capacitively coupled rf discharges (2f-CCRF) in the background of multi-component plasma is experimentally studied by rf current-voltage measurements and optical emission spectroscopy (OES). The multi-component plasma is produced by adding hydrogen to the argon CCRF discharge. Variation of experimental parameters, like working pressure, low frequency (LF) and high frequency (HF) rf power indicate significant changes in the electron density and temperature as well as the DC self-bias developed on the power electrode. It is observed that the electron density decreases as the percentage of hydrogen increases in the argon plasma while the electron temperature follows opposite trend. An analytical sheath model for the 2f-CCRF discharge in the background of multi-component plasma is developed and its prediction on the observed variation of DC self-bias is well agreed with the experimental observations. Authors acknowledge Proyecto Puente No P1611 and FONDECYT 3160179.

  5. Determination of vitamin C and preservatives in beverages by conventional capillary electrophoresis and microchip electrophoresis with capacitively coupled contactless conductivity detection.

    PubMed

    Law, Wai Siang; Kubán, Pavel; Zhao, Jian Hong; Li, Sam Fong Yau; Hauser, Peter C

    2005-12-01

    The separation and detection of commonly used preservatives (benzoate, sorbate) and vitamin C by both conventional CE and microchip electrophoresis with capacitively coupled contactless conductivity detection is presented. The separation was optimized by adjusting the pH-value of the buffer and the use of hydroxypropyl-beta-CD (HP-beta-CD) and CTAB as additives. For conventional CE, optimal separation conditions were achieved in a histidine/tartrate buffer at pH 6.5, containing 0.025% HP-beta-CD and 0.1 mM CTAB. LOD ranged from 0.5 to 3 mg/L (S/N = 3) and the RSDs for migration time and peak area were less than 0.1 and 2%, respectively. A considerable reduction of analysis time can be accomplished by using microchip electrophoresis without significant loss in sensitivity under optimal separation conditions. A histidine/tartrate buffer at pH 6.5, incorporating 0.06% HP-beta-CD and 0.25 mM CTAB, gave detection limits ranging between 3 and 10 mg/L and satisfactory reproducibilities of < or =0.4% for the migration time and < or =3.5% for the peak area. The methods developed are useful for the quantitative determination of food additives in real samples such as soft drinks and vitamin C tablets.

  6. Experimental study of a very high frequency (162MHz) capacitively coupled multi-tile electrode plasma source

    NASA Astrophysics Data System (ADS)

    Sirse, Nishant; Ellingboe, Bert

    2015-09-01

    In the recent years, plasma discharges excited at very high frequency (30-500MHz) has attracted much attention due to its ability to perform etching and deposition of large area substrates. VHF discharges yield high plasma density and low electron temperature and enable enhanced plasma dissociation. However, the plasma chemistry and power coupling mechanism in VHF discharges is not fully understood. In this article, we present an experimental study on nitrogen plasma produced by a VHF (162 MHz) multi-tile electrode. Electron density profile and gas temperature (rotational and vibrational) are measured as a function of rf power (100-1500W) and gas pressure (50mTorr-1Torr). Tile centre and Tile edge data are presented to realize the power coupling mechanism at different position in the multi-tile electrode discharge. It is observed that the plasma density increases monotonically with a rise in VHF power level at both positions while decreasing with an increase in the operating gas pressure. At a low gas pressure (50mTorr), plasma density profile shows a maximum at the tile centre and minimum at the tile edge position, whereas, at high gas pressures (500mTorr - 1 Torr) edge effects are observed. Measured rotational temperature (~ 350-450 K) is slightly above room temperature. Vibrational temperature, measured from 6500-8000 K, is increasing initially with a rise in rf power (<1 kW) and then saturates (above 1 kW). Similar to the plasma density profile, high vibrational temperature is measured at the tile edge compared to the tile centre.

  7. Characterization of a capacitance-coupled contactless conductivity detection system with sidewall electrodes on a low-voltage-driven electrophoresis microchip.

    PubMed

    Xu, Yi; Liang, Jing; Liu, Haitao; Hu, Xiaoguo; Wen, Zhiyu; Wu, Yongjie; Cao, Mingxia

    2010-06-01

    A new type of capacitance-coupled contactless conductivity detection (C(4)D) system with sidewall electrodes was proposed for integration on a silicon-on-isolator-poly(dimethylsiloxane) (SOI-PDMS) hybrid low-voltage-driven electrophoresis microchip. By a microelectromechanical system process, the sidewall electrodes were fabricated precisely at either side of the separation channel. The area of the capacitor electrodes was the maximum value to improve the detection sensitivity with an enhanced capacitance effect. According to the simulation results, the structural parameters of the sidewall electrodes were determined as 550-microm length, 15-microm width, 80-microm separation distance, and 1-microm isolator thickness. The integrated microdevice with the SOI-PDMS hybrid electrophoresis microchip was very compact and the size was only 15 cm x 15 cm x 10 cm (width x length x height), which permitted miniaturization and portability. The detector performance was evaluated by K(+) testing. The detection limit of the conductivity detector was determined to be 10(-9) and 10(-6) M for K(+) in the static and electric-driven modes, respectively. Finally, the C(4)D was applied to low-voltage-driven electrophoresis on a microchip to carry out real-time measurement of the separation of amino acids. The separations of 10(-4) M lysine and phenylalanine in the low-voltage-driven electrophoresis mode were performed with an electric field of 300 V/cm and were completed in less than 15 min with a resolution of 1.3. The separation efficiency was found to be 1.3 x 10(3) and 2.8 x 10(3) plates for lysine and phenylalanine, respectively, with a migration time reproducibility of 2.7 and 3.2%. The conductivity detection limit of amino acids achieved was 10(-6) M. The proposed method for the construction of a novel C(4)D integrated on an SOI-PDMS hybrid low-voltage-driven electrophoresis microchip showed the most extensive integration and miniaturization of a microdevice, which is a further

  8. 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.

  9. 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.

  10. Capacitive label reader

    DOEpatents

    Arlowe, H.D.

    1985-11-12

    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. 5 figs.

  11. Capacitive label reader

    DOEpatents

    Arlowe, H. Duane

    1985-01-01

    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.

  12. Disk-jet coupling in the Galactic black hole X-ray binary MAXI J1836-194

    NASA Astrophysics Data System (ADS)

    Russell, Thomas

    2014-01-01

    There is a universal connection between the accretion and ejection phenomena that are observed in black holes across the mass scale. Quantifying this relationship is the first step in understanding how jets are launched, accelerated and collimated. X-ray binaries are ideal systems to study this relationship, as they evolve on human timescales. In outburst, their luminosities increase by several orders of magnitude, with the thermal X-ray emission from the accretion disk and the radio emission from the relativistic jets undergoing dramatic, coupled changes. We present the results of our multiwavelength radio through to X-ray observations of the Galactic black hole candidate X-ray binary MAXI J1836-194 during its 2011 outburst. We find that this system has a near face-on accretion disk with the jet, that is pointed almost directly towards us, accounting for ~6% of the total energy output of the system early in the outburst. We observed the frequency of the transition from optically thick to optically thin synchrotron emission in the jet spectrum evolve by ~3 orders of magnitude as the jet gradually switches on and off on a timescale of a few weeks. This evolution does not appear to follow the expected positive relation with source luminosity. Instead the jet break shifted to higher frequencies as the source luminosity decreased and is likely coupled to the accretion flow in a more complex way. We find the region where the jet is accelerated up to relativistic speeds occurs at much larger distances from the black hole than previously thought and does not scale with the inner radius of the accretion disk. Our simultaneous, high cadence observations provide an unprecedented insight into the accretion processes occurring during an outburst, allowing us to observe the compact jet evolve and the corresponding changes within the accretion regime. This has implications for the launching of jets on all scales, from X-ray binaries to their larger-scale analogues, AGN.

  13. 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; 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

  14. Rating systems for evaluation of functional ankle instability: prospective evaluation in a cohort of patients treated with monopolar capacitive-coupled radiofrequency.

    PubMed

    Cronkey, Joseph; LaPorta, Guido

    2012-10-01

    Evaluation of patient outcomes should include the use of validated scoring systems to determine disease-specific outcomes. Many scoring systems are being used for disorders of the ankle joint. However, not all instruments are capable of detecting changes associated with functional ankle instability (FAI), since their focus is toward pathological entities with greater impact on individual's physical and mental well-being. In this prospective study, 6 instruments were used to evaluate outcomes associated with an intervention aimed at improving FAI. Twenty ankles that had been unsuccessfully treated for FAI were treated with a single session of noninvasive monopolar capacitive-coupled radiofrequency (mcRF) and followed prospectively. Five out of 6 instruments failed to show changes that could be correlated with patients' outcomes. Only one instrument, the Cumberland Ankle Instability Tool (CAIT) demonstrated enough sensitivity and correlated well with meaningful clinical differences. Based on study's success criteria (proper function, no pain, no adverse events, and patient satisfaction), 78% of the ankles treated had successful outcomes whereas 87.5% evidenced significant improvement based on CAIT (P < .001). No adverse events were present during the study. The study of FAI is hampered by the lack of disease-specific questionnaires, which oftentimes introduce ceiling or flooring effects. The CAIT was capable of detecting changes in patients' condition and response to the noninvasive mcRF procedure without evidencing ceiling or flooring effects. In this study, the CAIT was found to be reliable, valid, sensitive to changes of clinical importance, in addition to being short and practical to use.

  15. The effect of realistic heavy particle induced secondary electron emission coefficients on the electron power absorption dynamics in single- and dual-frequency capacitively coupled plasmas

    NASA Astrophysics Data System (ADS)

    Daksha, M.; Derzsi, A.; Wilczek, S.; Trieschmann, J.; Mussenbrock, T.; Awakowicz, P.; Donkó, Z.; Schulze, J.

    2017-08-01

    In particle-in-cell/Monte Carlo collisions (PIC/MCC) simulations of capacitively coupled plasmas (CCPs), the plasma-surface interaction is generally described by a simple model in which a constant secondary electron emission coefficient (SEEC) is assumed for ions bombarding the electrodes. In most PIC/MCC studies of CCPs, this coefficient is set to γ = 0.1, independent of the energy of the incident particle, the electrode material, and the surface conditions. Here, the effects of implementing energy-dependent secondary electron yields for ions, fast neutrals, and taking surface conditions into account in PIC/MCC simulations is investigated. Simulations are performed using self-consistently calculated effective SEECs, {γ }* , for ‘clean’ (e.g., heavily sputtered) and ‘dirty’ (e.g., oxidized) metal surfaces in single- and dual-frequency discharges in argon and the results are compared to those obtained by assuming a constant secondary electron yield of γ =0.1 for ions. In single-frequency (13.56 MHz) discharges operated under conditions of low heavy particle energies at the electrodes, the pressure and voltage at which the transition between the α- and γ-mode electron power absorption occurs are found to strongly depend on the surface conditions. For ‘dirty’ surfaces, the discharge operates in α-mode for all conditions investigated due to a low effective SEEC. In classical dual-frequency (1.937 MHz + 27.12 MHz) discharges {γ }* significantly increases with increasing low-frequency voltage amplitude, {V}{LF}, for dirty surfaces. This is due to the effect of {V}{LF} on the heavy particle energies at the electrodes, which negatively influences the quality of the separate control of ion properties at the electrodes. The new results on the separate control of ion properties in such discharges indicate significant differences compared to previous results obtained with different constant values of γ.

  16. 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.

  17. Degenerate Wave and Capacitive Coupling Increase Human MSC Invasion and Proliferation While Reducing Cytotoxicity in an In Vitro Wound Healing Model

    PubMed Central

    Griffin, Michelle; Iqbal, Syed Amir; Sebastian, Anil; Colthurst, James; Bayat, Ardeshir

    2011-01-01

    Non-unions pose complications in fracture management that can be treated using electrical stimulation (ES). Bone marrow mesenchymal stem cells (BMMSCs) are essential in fracture healing; however, the effect of different clinical ES waveforms on BMMSCs cellular activities remains unknown. We compared the effects of direct current (DC), capacitive coupling (CC), pulsed electromagnetic field (PEMF) and degenerate wave (DW) on cellular activities including cytotoxicity, proliferation, cell-kinetics and apoptosis by stimulating human-BMMSCs 3 hours a day, up to 5 days. In addition, migration and invasion were assessed using fluorescence microscopy and by quantifying gene and protein expression. We found that DW had the greatest proliferative and least apoptotic and cytotoxic effects compared to other waveforms. DC, DW and CC stimulations resulted in a higher number of cells in S phase and G2/M phase as shown by cell cycle analysis. CC and DW caused more cells to invade collagen and showed increased MMP-2 and MT1-MMP expression. DC increased cellular migration in a scratch-wound assay and all ES waveforms enhanced expression of migratory genes with DC having the greatest effect. All ES treated cells showed similar progenitor potential as determined by MSC differentiation assay. All above findings were shown to be statistically significant (p<0.05). We conclude that ES can influence BMMSCs activities, especially DW and CC, which show greater invasion and higher cell proliferation compared to other types of ES. Application of DW or CC to the fracture site may help in the recruitment of BMMSCs to the wound that may enhance rate of bone healing at the fracture site. PMID:21858102

  18. 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.

  19. 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.

  20. 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.

  1. 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.

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

    NASA Astrophysics Data System (ADS)

    Gul, Banat; Aman-ur-Rehman

    2015-10-01

    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+, Br+, 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.

  3. 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.

  4. High energy electron fluxes in dc-augmented capacitively coupled plasmas. II. Effects on twisting in high aspect ratio etching of dielectrics

    SciTech Connect

    Wang Mingmei; Kushner, Mark J.

    2010-01-15

    In high aspect ratio (HAR) plasma etching of holes and trenches in dielectrics, sporadic twisting is often observed. Twisting is the randomly occurring divergence of a hole or trench from the vertical. Many causes have been proposed for twisting, one of which is stochastic charging. As feature sizes shrink, the fluxes of plasma particles, and ions in particular, into the feature become statistical. Randomly deposited charge by ions on the inside of a feature may be sufficient to produce lateral electric fields which divert incoming ions and initiate nonvertical etching or twisting. This is particularly problematic when etching with fluorocarbon gas mixtures where deposition of polymer in the feature may trap charge. dc-augmented capacitively coupled plasmas (dc-CCPs) have been investigated as a remedy for twisting. In these devices, high energy electron (HEE) beams having narrow angular spreads can be generated. HEEs incident onto the wafer which penetrate into HAR features can neutralize the positive charge and so reduce the incidence of twisting. In this paper, we report on results from a computational investigation of plasma etching of SiO{sub 2} in a dc-CCP using Ar/C{sub 4}F{sub 8}/O{sub 2} gas mixtures. We found that HEE beams incident onto the wafer are capable of penetrating into features and partially neutralizing positive charge buildup due to sporadic ion charging, thereby reducing the incidence of twisting. Increasing the rf bias power increases the HEE beam energy and flux with some indication of improvement of twisting, but there are also changes in the ion energy and fluxes, so this is not an unambiguous improvement. Increasing the dc bias voltage while keeping the rf bias voltage constant increases the maximum energy of the HEE and its flux while the ion characteristics remain nearly constant. For these conditions, the occurrence of twisting decreases with increasing HEE energy and flux.

  5. Optical diagnostics for the highly populated tail of an electron energy distribution function in very-high-frequency capacitively coupled plasma using spin- and dipole-forbidden lines

    NASA Astrophysics Data System (ADS)

    Roh, Hyun-Joon; Kim, Nam-Kyun; Ryu, Sangwon; Jang, Yunchang; Kim, Gon-Ho

    2017-06-01

    A novel method is proposed to determine an electron energy distribution function (EEDF) that includes the highly populated tail originated by energetic beam-like electrons (>20 eV), which often occur in narrow gap, very-high-frequency capacitively coupled plasma (VHF-CCP). This method combines conventional Langmuir probe analysis to represent the EEDF in the low-energy regime and the line-ratio method taken from the optical emission spectrum to represent the highly populated tail of the EEDF. Here the emission lines are chosen with consideration of the excitation rates, which are a function of the shape of the cross-section of the spin- and dipole-forbidden states of an argon atom and the EEDF at corresponding energy. In this method, the analytical EEDF model is chosen for the composition of the Maxwellian for low-energy (bulk) electrons, and Schulze’s time-averaged form of the shifted Maxwellian (Schulze et al 2008 J. Phys. D: Appl. Phys. 41 042003) is chosen for the highly populated tail of the EEDF. The variables of the time-averaged form of the shifted Maxwellian, the fraction and mean energy of the beam-like electrons, are determined using an emission model of line-intensity ratios, which describes the line-intensities as a function of the EEDF. This method is advantageous for the diagnostics of a time-averaged EEDF with a highly populated tail, especially where this is due to beam-like electrons that originate from stochastic heating, compared to a two-temperature EEDF.

  6. Thermal and electric energy fields by noninvasive monopolar capacitive-coupled radiofrequency: temperatures achieved and histological outcomes in tendons and ligaments.

    PubMed

    Whipple, Terry; Villegas, Diana

    2010-07-01

    To determine whether noninvasive monopolar capacitive-coupled radiofrequency (mcRF) can produce energy and thermal fields capable of breaking-down collagen molecules in deep connective structures without damaging untargeted tissues as evidenced by temperatures achieved and histological outcomes. Basic science study on fresh untreated cadaveric specimens. Orthopaedic Research of Virginia (Institutional). Two upper and two lower extremities from cadaveric specimens were obtained for the study. Anatomical structures were surgically exposed. Fluoroptic thermometers were implanted into the mid-substance of the targeted structures as well as in the skin above the structures to be studied. mcRF pulses were delivered to the area of interest, and temperatures were recorded every second. Multiple samples of tissue from each treatment site and stage of treatment were harvested for analysis. Outcomes were evaluated by temperature changes in response to energy fields, multiobserver histological analysis under regular and polarized light, and direct observation of the tissues in the areas exposed to RF energy. Temperatures recorded at the targeted structures reached above 50 degrees C, as evidenced by the implanted thermometers. Histological analysis under regular and polarized light evidenced a progressive pattern of collagen denaturation that correlated well with temperatures recorded. This study established a direct relationship between noninvasive mcRF energy and temperatures recorded in deep structures (P<.001). Histological examination under regular and polarized light suggested that collagen changes are dose related. No evidence of damage to the nontargeted structures or to the tissue superficial to targeted structures was observed. As it has been demonstrated in survival animal studies, it is anticipated that the outcome of the changes induced in collagen fibers would trigger a desirable wound healing response. These findings can provide a meaningful context to the

  7. Evaluation of Solid-Solution Hardening in Several Binary Alloy Systems Using Diffusion Couples Combined with Nanoindentation

    NASA Astrophysics Data System (ADS)

    Kadambi, Sourabh B.; Divya, V. D.; Ramamurty, U.

    2017-10-01

    Analysis of solid-solution hardening (SSH) in alloys requires the synthesis of large composition libraries and the measurement of strength or hardness from these compositions. Conventional methods of synthesis and testing, however, are not efficient and high-throughput approaches have been developed in the past. In the present study, we use a high-throughput combinatorial approach to examine SSH at large concentrations in binary alloys of Fe-Ni, Fe-Co, Pt-Ni, Pt-Co, Ni-Co, Ni-Mo, and Co-Mo. The diffusion couple (DC) method is used to generate concentration ( c) gradients and the nanoindentation (NI) technique to measure the hardness ( H) along these gradients. The obtained H -c profiles are analyzed within the framework of the Labusch model of SSH, and the c^{2/3} dependence of H predicted by the model is found to be generally applicable. The SSH behavior obtained using the combinatorial method is found to be largely consistent with that observed in the literature using conventional and DC-NI methods. This study evaluates SSH in Fe-, Ni-, Co-, and Pt-based binary alloys and confirms the applicability of the DC-NI approach for rapidly screening various solute elements for their SSH ability.

  8. 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.

  9. Multiscale Coupling of Monte Carlo Binary-Collision-Approximation Codes with Particle-in-Cells for Plasma-Material Interaction

    NASA Astrophysics Data System (ADS)

    Curreli, Davide; Lindquist, Kyle; Ruzic, David N.

    2013-10-01

    Techniques based on Monte Carlo Binary Collision Approximation (BCA) are widely used for the evaluation of particle interactions with matter, but rarely coupled with a consistent kinetic plasma solver like a Particle-in-Cell. The TRIM code [Eckstein; Biersack and Haggmark, 1980] and its version including dynamic-composition TRIDYN [Moller and Eckstein, 1984] are two popular implementations of BCA, where single-particle projectiles interact with a target of amorphous material according to the classical Carbon-Krypton interaction potential. The effect of surface roughness can be included as well, thanks to the Fractal-TRIM method [Ruzic and Chiu, 1989]. In the present study we couple BCA codes with Particles-in-Cells. The Lagrangian treatment of particle motion usually implemented in PiC codes suggests a natural coupling of PiC's with BCA's, even if a number of caveats has to be taken into account, related to the discrete nature of computational particles, to the difference between the two approaches and most important to the multiple spatial and temporal scales involved. The break down of BCA at low energies (unless the projectiles are channeling through an oriented crystal layer [Hobler and Betz, 2001]) has been supplemented by Yamamura's semi-empirical relations.

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

    DOE PAGES

    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

  11. Bistable magnetoresistance switching in exchange-coupled CoFe₂O₄--Fe₃O₄ binary nanocrystal superlattices by self-assembly and thermal annealing.

    PubMed

    Chen, Jun; Ye, Xingchen; Oh, Soong Ju; Kikkawa, James M; Kagan, Cherie R; Murray, Christopher B

    2013-02-26

    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 °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 °C even exhibit bistable magnetoresistance switching behavior at room temperature constituting a simple nonvolatile memory function.

  12. 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.

  13. A portable lab-on-a-chip instrument based on MCE with dual top-bottom capacitive coupled contactless conductivity detector in replaceable cell cartridge.

    PubMed

    Ansari, Kambiz; Ying, Jasmine Yuen Shu; Hauser, Peter C; de Rooij, Nico F; Rodriguez, Isabel

    2013-05-01

    A new design for a compact portable lab-on-a-chip instrument based on MCE and dual capacitively coupled contactless conductivity detection (dC(4) D) is described. The instrument is battery powered with total dimension of 14 × 25 × 8 cm(3) (w × l × h), and weighs 1.2 kg. The device consists of a front electrophoresis compartment which has the chip holder and the chip, the associated high-voltage electrodes for electrophoresis injection and separation and the detector. The detection cell is integrated into the device housing with an exchangeable plug-and-play cartridge format. The design of the dC(4) D cell has been optimized for maximum performance. The cartridge includes the top-bottom excitation and pick up electrodes incorporated into the cell and connected to push-pull self-latching pins that are insulated with plastic. The metal frame of the cartridge is grounded completely to eliminate electronic interferences. The cartridge is designed to clamp a thin fluidic chip at the detection point. The cartridges are replaceable whereby different cartridges have different detection electrode configurations to employ according to the sensitivity or resolution needed in the specific analytical application. The second compartment consists of all the electronics, data acquisition card, high-voltage modules of up to ±5 kV both polarity, and batteries for 10 h of operation. The improved detector performance is illustrated by the electrophoresis analysis of six cations (NH4 (+) , K(+) , Ca(2+) , Na(+) , Mg(2+) , Li(+) ) with a detection limit of approximately 5 μM and the analysis of the anions (Br(-) , Cl(-) , NO2 (-) , NO3 (-) , SO4 (2-) , F(-) ) with a detection limit of about 3 μM. Analytical capabilities of the instrument for food and medical applications were evaluated by simultaneous detection of organic and inorganic acids in fruit juice and inorganic cations and anions in rabbit blood samples and human urine samples are also demonstrated. © 2013 WILEY

  14. Role of the blocking capacitor in control of ion energy distributions in pulsed capacitively coupled plasmas sustained in Ar/CF{sub 4}/O{sub 2}

    SciTech Connect

    Song, Sang-Heon; Kushner, Mark J.

    2014-03-15

    In plasma etching for microelectronics fabrication, the quality of the process is in large part determined by the ability to control the ion energy distribution (IED) onto the wafer. To achieve this control, dual frequency capacitively coupled plasmas (DF-CCPs) have been developed with the goal of separately controlling the magnitude of the fluxes of ions and radicals with the high frequency (HF) and the shape of the IED with the low frequency (LF). In steady state operation, plasma properties are determined by a real time balance between electron sources and losses. As such, for a given geometry, pressure, and frequency of operation, the latitude for controlling the IED may be limited. Pulsed power is one technique being investigated to provide additional degrees of freedom to control the IED. In one configuration of a DF-CCP, the HF power is applied to the upper electrode and LF power is applied to the lower electrode which is serially connected to a blocking capacitor (BC) which generates a self dc-bias. In the steady state, the value of the dc-bias is, in fact, constant. During pulsed operation, however, there may be time modulation of the dc-bias which provides an additional means to control the IED. In this paper, IEDs to the wafer in pulsed DF-CCPs sustained in Ar/CF{sub 4}/O{sub 2} are discussed with results from a two-dimensional plasma hydrodynamics model. The IED can be manipulated depending on whether the LF or HF power is pulsed. The dynamic range of the control can be tuned by the dc-bias generated on the substrate, whose time variation depends on the size of the BC during pulsed operation. It was found that high energy ions can be preferentially produced when pulsing the HF power and low energy ions are preferentially produced when pulsing the LF power. A smaller BC value which allows the bias to follow the change in charged particle fluxes produces a larger dynamic range with which to control IEDs.

  15. 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; 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

  16. Poly-(3-hexylthiophene) Aggregate Formation in Binary Solvent Mixtures: An Excitonic Coupling Analysis

    NASA Astrophysics Data System (ADS)

    Boucher, David; Johnson, Calynn

    2014-03-01

    We have studied the aggregation behavior of P3HT [Mn ~ 28.2 kDa, regioregularity >96 %, PDI ~ 1.3] in 96 solvent mixtures is studied using UV-Vis absorption spectroscopy. We used Hansen solubility parameters (HSPs) and Spano excitonic coupling analyses to identify correlations between the properties of the solvent mixtures and the extent of structural order of the aggregates. It is clear that the identity of the poor solvent used to drive aggregation has a significant impact on the excitonic coupling behavior and, hence, the structural order of the P3HT aggregates. However, solubility parameter theory does not account nor provide a predictive theory for the observed trends. Instead, qualitative arguments based on the nature of the interactions between the solvents and the polythiophene and hexyl side chain motifs are used to rationalize the kinetics of formation and the observed excitonic coupling characteristics of the P3HT aggregates.

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

    SciTech Connect

    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 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. Effect of adding small amount of inductive fields to O{sub 2}, Ar/O{sub 2} capacitively coupled plasmas

    SciTech Connect

    Lee, Min-Hyong; Lee, Hyo-Chang; Chung, Chin-Wook

    2012-05-01

    Electron energy distribution functions (EEDFs) of low pressure O{sub 2} plasma were measured by adding small amount of coil power in a capacitive discharge. When the plasma was generated by bias power only, the measured EEDF showed a bi-Maxwellian distribution. However, when a very small coil power (a few Watts) was added, the EEDF evolved abruptly into a Maxwellian distribution, while the electron density was decreased. In an Ar/O{sub 2} mixture discharge, this EEDF evolution to the Maxwellian was also observed at a relatively higher coil power. This abrupt change in EEDFs with a very small coil power appears to be attributed to a combined effect of collisionless heating by capacitive and induced electric fields.

  19. 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

  20. 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.

  1. 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.

  2. 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.

  3. Detection of particles of less than 5 nm in diameter formed in an argon-silane capacitively coupled radio-frequency discharge

    NASA Astrophysics Data System (ADS)

    Boufendi, L.; Gaudin, J.; Huet, S.; Viera, G.; Dudemaine, M.

    2001-12-01

    A method for the detection of dust particles occurring in silane-argon gas mixture plasmas is presented. It is based on the spectral analysis of the radio-frequency current. The amplitudes of the fundamental (13.56 MHz) and second harmonics (40.68 MHz) are very sensitive to the presence of the earlier nanoparticles when their size is in the range of 2-3 nm even if their influence on the capacitive character of the impedance is negligible. This method is nonperturbative, with a temporal resolution in the microsecond range, very easy to implement, and can thus be used for industrial reactors.

  4. Altering the sulfur content in the propanethiol plasma polymers using the capacitive-to-inductive mode transition in inductively coupled plasma discharge

    SciTech Connect

    Thiry, Damien; Britun, Nikolay; Konstantinidis, Stephanos; Dauchot, Jean-Pierre; Denis, Laurent; Snyders, Rony

    2012-02-13

    The effect of the transition from capacitive (E) to inductive (H) mode on propanethiol plasma polymer films properties was investigated by optical emission as well as by x-ray photoelectron spectroscopy. The E mode is characterized by low deposition rate and by high sulfur content in the films ({approx}40% vs {approx}20% in H mode). After aging, a strong decrease of sulfur to carbon content (from {approx}0.75 to 0.13), attributed to desorption of unbounded sulfur-based molecules (e.g., H{sub 2}S), is detected at low power in E mode. The importance of the E-H transition for altering the film properties is highlighted.

  5. 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.

  6. Measurement of electron temperatures and electron energy distribution functions in dual frequency capacitively coupled CF{sub 4}/O{sub 2} plasmas using trace rare gases optical emission spectroscopy

    SciTech Connect

    Chen Zhiying; Donnelly, Vincent M.; Economou, Demetre J.; Chen, Lee; Funk, Merritt; Sundararajan, Radha

    2009-09-15

    Measurements of electron temperatures (T{sub e}) and electron energy distribution functions (EEDFs) in a dual frequency capacitively coupled etcher were performed by using trace rare gas optical emission spectroscopy (TRG-OES). The parallel plate etcher was powered by a high frequency (60 MHz) ''source'' top electrode and a low frequency (13.56 MHz) ''substrate'' bottom electrode. T{sub e} first increased with pressure up to {approx}20 mTorr and then decreased at higher pressures. Increasing the bottom rf power resulted in higher electron temperatures. Electron temperatures in 90% CF{sub 4}+10% O{sub 2} plasmas were similar to those in 80% CF{sub 4}+20% O{sub 2} plasmas. EEDF exhibited bi-Maxwellian characteristics with enhanced high energy tail, especially at pressures >20 mTorr.

  7. Modeling of Feature Profile Evolution in SiO2 as functions of Radial Position and Bias Voltage under Competition among Charging, Deposition, and Etching in Two-Frequency Capacitively Coupled Plasma

    NASA Astrophysics Data System (ADS)

    Shimada, Takashi; Yagisawa, Takashi; Makabe, Toshiaki

    2006-11-01

    A feature profile evolution model of a trench in SiO2 is developed in a two-frequency capacitively coupled plasma in CF4(5%)/Ar by considering two layers, a mixing layer and an overlaying polymer layer on the basis of a database of etching yield by extending our original physical computer-aided design (CAD) tool, VicAddress (vertically integrated computer-aided design for device processes). That is, the surface exposed to fluorocarbon plasma is considered under competition among the charging of electrons and ions, the deposition of radicals, and reactive etching by ions. The feature profile is also discussed in terms of the bias amplitude and the position on the wafer.

  8. Effect of driving frequency on the electron-sheath interaction and electron energy distribution function in a low pressure capacitively coupled plasmas

    NASA Astrophysics Data System (ADS)

    Sharma, Sarveshwar; Sirse, Nishant; Kaw, Predhiman; Turner, Miles; Ellingboe, Albert R.; InstitutePlasma Research, Gandhinagar, Gujarat Team; School Of Physical Sciences; Ncpst, Dublin City University, Dublin 9, Ireland Collaboration

    2016-09-01

    The effect of driving frequency (27.12-70 MHz) on the electron-sheath interaction and electron energy distribution function (EEDF) is investigated in a low pressure capacitive discharges using a self-consistent particle-in-cell simulation. At a fixed discharge voltage the EEDF evolves from a strongly bi-Maxwellian at low frequency, 27.12 MHz, to a convex type distribution at an intermediate frequency, 50 MHz, and finally becomes a weak biMaxwellian above 50 MHz. The EEDF evolution leads to a two-fold increase in the effective electron temperature up to 50 MHz, whereas the electron density remains constant in this range. After 50MHz, the electron density increases rapidly and the electron temperature decreases. The transition is caused by the transient electric field excited by bursts of high energy electrons interacting strongly with the sheath edge. Above the transition frequency, high energy electrons are confined between two sheaths which increase the ionization probability and thus the plasma density increases.

  9. 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.

  10. 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).

  11. 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.

  12. 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

    2013-06-07

    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.

  13. 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.

  14. Striations in electronegative capacitively coupled radio-frequency plasmas: analysis of the pattern formation and the effect of the driving frequency

    NASA Astrophysics Data System (ADS)

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

    2017-05-01

    Self-organized striated structures of the plasma emission have recently been observed in capacitive radio-frequency CF4 plasmas by phase resolved optical emission spectroscopy (PROES) and their formation was analyzed and understood by particle in cell/Monte Carlo collision (PIC/MCC) simulations (Liu et al 2016 Phys. Rev. Lett. 116 255002). The striations were found to result from the periodic generation of double layers due to the modulation of the densities of positive and negative ions responding to the externally applied RF potential. In this work, an in-depth analysis of the formation of striations is given, as well as the effect of the driving frequency on the plasma parameters, such as the spatially modulated charged species densities, the electric field, and the electron power absorption is studied by PROES measurements, PIC/MCC simulations, and an ion-ion plasma model. The measured spatio-temporal electronic excitation patterns at different driving frequencies show a high degree of consistency with the simulation results. The striation gap (i.e., the distance between two ion density maxima) is found to be inversely proportional to the driving frequency. In the presence of striations the minimum ({{{CF}}}3+, {{{F}}}-) ion densities in the bulk region exhibit an approximately quadratic increase with the driving frequency. For these densities, the eigenfrequency of the ion-ion plasma is near the driving frequency, indicating that a resonance occurs between the positive and negative ions and the oscillating electric field inside the plasma bulk. The maximum ion densities in the plasma bulk are found not to exhibit a simple dependence on the driving frequency, since these ion densities are abnormally enhanced within a certain frequency range due to the ions being focused into the ‘striations’ by the spatially modulated electric field inside the bulk region.

  15. ``Zeptofarad'' (10-21 F) resolution capacitance sensor for scanning capacitance microscopy

    NASA Astrophysics Data System (ADS)

    Tran, T.; Oliver, D. R.; Thomson, D. J.; Bridges, G. E.

    2001-06-01

    We describe a sensor for use in a scanning capacitance microscope (SCM) that is capable of "zeptofarad" (10-21 F) capacitance measurement resolution in a 1 Hz bandwidth with a peak-to-peak sense voltage on the probe tip of no more than 300 mV. This sensitivity is based on experimental data and simulation results that are in excellent agreement. The complete sensor incorporates an oscillator (phase locked to a 10 MHz crystal oscillator), a coupled transmission line resonator, an amplifier, and a peak detector. The resonator is fabricated from copper-clad, low-loss dielectric material and its size is such that it is easily incorporated with a scanning probe microscope. The sensor's use in the SCM enables capacitance resolution that has not previously been possible while retaining the instrumental advantages of imaging at low sense voltages. The performance of this sensor is discussed and compared to alternative scanning capacitance microscopy methodologies.

  16. 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

  17. 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

    Bifulco, Paolo; Massa, Rita; Cesarelli, Mario; Romano, Maria; Fratini, Antonio; Gargiulo, Gaetano D; McEwan, Alistair L

    2013-08-12

    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. 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 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. 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 the electrodes. This outcome is concordant

  18. 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. Copyright © 2013 Elsevier Ltd. All

  19. Capacitance Flatness Gauge Prototype

    SciTech Connect

    Pitas, A.; Angstadt, R.; /Fermilab

    1986-03-20

    The DO calorimeter has within it thousands of large plates. Our ability to construct the detector depends on the flatness of these plates. The performance of the detector depends on the flatness of the plates after they are assembled into a module. It has been proposed that the flatness of the plates before and after assembly could be determined by measuring capacitance. This device demonstrates the viability of using capacitance to measure the flatness of individual plates. No attempt has been made to extrapolate the results to measuring the flatness of the plates once they are in a module.

  20. 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

  1. 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.

  2. 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.

  3. 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.

  4. Steerable Capacitive Proximity Sensor

    NASA Technical Reports Server (NTRS)

    Jenstrom, Del T.; Mcconnell, Robert L.

    1994-01-01

    Steerable capacitive proximity sensor of "capaciflector" type based partly on sensing units described in GSC-13377 and GSC-13475. Position of maximum sensitivity adjusted without moving sensor. Voltage of each driven shield adjusted separately to concentrate sensing electric field more toward one side or other.

  5. 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.

  6. Quantum and tunneling capacitance in charge and spin qubits

    NASA Astrophysics Data System (ADS)

    Mizuta, R.; Otxoa, R. M.; Betz, A. C.; Gonzalez-Zalba, M. F.

    2017-01-01

    We present a theoretical analysis of the capacitance of a double quantum dot in the charge and spin qubit configurations probed at high frequencies. We find that, in general, the total capacitance of the system consists of two state-dependent terms: the quantum capacitance arising from adiabatic charge motion and the tunneling capacitance that appears when repopulation occurs at a rate comparable or faster than the probing frequency. The analysis of the capacitance lineshape as a function of externally controllable variables offers a way to characterize the qubits' charge and spin state as well as relevant system parameters such as charge and spin relaxation rates, tunnel coupling, electron temperature, and electron g factor. Overall, our analysis provides a formalism to understand dispersive qubit-resonator interactions which can be applied to high-sensitivity and noninvasive quantum-state readout.

  7. 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

  8. The disc-jet coupling in the neutron star X-ray binary 4U 1728-34

    NASA Astrophysics Data System (ADS)

    Tudose, Valeriu; Tzioumis, Anastasios; Belloni, Tomaso; Altamirano, Diego; Linares, Manuel; Mendez, Mariano; Hiemstra, Beike

    2010-10-01

    The present radio proposal is part of a multi-wavelength campaign focused on the study of the accretion/ejection process in the neutron star X-ray binary system 4U 1728-34. Our intention is to study the behaviour of the inner part of the accretion disc as inferred from the X-ray observations of the Fe emission line and the kHz quasi-periodic oscillations, and to link it to the properties of the radio jet. To achieve this goal we request 5 × 11h of observing time with ATCA, scheduled at regular intervals in the period 2010 August 27- October 13, the visibility window of the granted X-ray observations with RXTE (PI: Mendez) and Suzaku (PI: Linares).

  9. 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.

  10. 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.

  11. Comparison of piezoresistive and capacitive ultrasonic transducers

    NASA Astrophysics Data System (ADS)

    Neumann, John J.; Greve, David W.; Oppenheim, Irving J.

    2004-07-01

    MEMS ultrasonic transducers for flaw detection have heretofore been built as capacitive diaphragm-type devices. A diaphragm forms a moveable electrode, placed at a short gap from a stationary electrode, and diaphragm movement has been detected by capacitance change. Although several research teams have successfully demonstrated that technology, the detection of capacitance change is adversely affected by stray and parasitic capacitances, limiting the sensitivity of such transducers and typically requiring relatively large diaphragm areas. We describe the design and fabrication of what to our knowledge is the first CMOS-MEMS ultrasonic phased array transducer using piezoresistive strain sensing. Piezoresistors have been patterned within the diaphragms, and diaphragm movement creates bending strain which is detected by a bridge circuit, for which conductor losses will be less significant. The prospective advantage of such piezoresistive transducers is that sufficient sensitivity may be achieved with very small diaphragms. We compare transducer response under fluid-coupled ultrasonic excitation and report the experimental gauge factor for the piezoresistors. We also discuss the phased array performance of the transducer in sensing the direction of an incoming wave.

  12. Measurement of F-, O- and CF_{3}^{-} densities in 60 and 100 MHz asymmetric capacitively coupled plasma discharge produced in an Ar/O2/C4F8 gas mixture

    NASA Astrophysics Data System (ADS)

    Sirse, N.; Tsutsumi, T.; Sekine, M.; Hori, M.; Ellingboe, A. R.

    2017-08-01

    The behaviour of absolute electron density and density of F-, O- and CF3- is studied in asymmetric capacitively coupled plasma discharge produced in an Ar/O2/C4F8 (80:10:10) gas mixture excited at 60 and 100 MHz. The measurements are performed using a hairpin probe and laser photo-detachment at 532 nm and 355 nm laser wavelengths. For both 60 and 100 MHz driving frequencies, the results show that the electrons and F- density increases almost linearly with the increase in rf power. On the other hand, the O- density increases in 60 MHz and decreases in 100 MHz with a rise in rf power. For a fixed rf power in the 60 MHz discharge, the O- density increases and electron density decreases with gas pressure. The corresponding F- density first increases, reaching a maximum value, and then decreases with a further increase in gas pressure. A similar trend in electron, F- and O- density versus gas pressure is observed in 100 MHz suggesting that the initial increase in densities is dominated by the ionization and dissociative attachment, whereas, at a higher gas pressure, electron-ion recombination, ion-neutral recombination and ion-ion neutralization play a significant role in the losses of charged particles. The ratio of F- density to O- density is ~80:20 and ~95:5 in 60 MHz and 100 MHz respectively. The density of both electrons and F- is higher in 100 MHz when compared to 60 MHz discharge. The observed trend is explained on the basis of productions and loss mechanisms for electrons and negative ions. It is concluded that the higher F- density in 100 MHz in comparison to 60 MHz is mainly due to higher electron density and dissociation degree.

  13. 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.

  14. 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.

  15. 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

  16. The "SIMCLAS" Model: Simultaneous Analysis of Coupled Binary Data Matrices with Noise Heterogeneity between and within Data Blocks

    ERIC Educational Resources Information Center

    Wilderjans, Tom F.; Ceulemans, E.; Van Mechelen, I.

    2012-01-01

    In many research domains different pieces of information are collected regarding the same set of objects. Each piece of information constitutes a data block, and all these (coupled) blocks have the object mode in common. When analyzing such data, an important aim is to obtain an overall picture of the structure underlying the whole set of coupled…

  17. 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.

  18. Multi-Channel Capacitive Sensor Arrays.

    PubMed

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

    2016-01-25

    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.

  19. 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

  20. Improved Capacitive Liquid Sensor

    NASA Technical Reports Server (NTRS)

    Waldman, Francis A.

    1992-01-01

    Improved capacitive sensor used to detect presence and/or measure thickness of layer of liquid. Electrical impedance or admittance of sensor measured at prescribed frequency, and thickness of liquid inferred from predetermined theoretical or experimental relationship between impedance and thickness. Sensor is basically a three-terminal device. Features interdigitated driving and sensing electrodes and peripheral coplanar ground electrode that reduces parasitic effects. Patent-pending because first to utilize ground plane as "shunting" electrode. System less expensive than infrared, microwave, or refractive-index systems. Sensor successfully evaluated in commercial production plants to characterize emulsions, slurries, and solutions.

  1. 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.

  2. 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.

  3. 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.

  4. 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.

  5. 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.

  6. Quantum Capacitance of a Topological Insulator-Ferromagnet Interface

    NASA Astrophysics Data System (ADS)

    Siu, Zhuo Bin; Chowdhury, Debashree; Jalil, Mansoor B. A.; Basu, Banasri

    2017-03-01

    We study the quantum capacitance in a topological insulator thin film system magnetized in the in-plane direction in the presence of an out-of-plane magnetic field and hexagonal warping. To first order, the modification in quantum capacitance due to hexagonal warping compared to the clean case, where both the in-plane magnetization and hexagonal warping are absent, is always negative, and increases in magnitude monotonically with the energy difference from the charge neutrality point. In contrast, the change in the quantum capacitance due to in-plane magnetization oscillates with the energy in general, except when a certain relation between the inter-surface coupling, out of plane Zeeman energy splitting and magnetic field strength is satisfied. In this special case, the quantum capacitance remains unchanged by the in-plane magnetization for all energies.

  7. Quantum Capacitance of a Topological Insulator-Ferromagnet Interface.

    PubMed

    Siu, Zhuo Bin; Chowdhury, Debashree; Jalil, Mansoor B A; Basu, Banasri

    2017-03-24

    We study the quantum capacitance in a topological insulator thin film system magnetized in the in-plane direction in the presence of an out-of-plane magnetic field and hexagonal warping. To first order, the modification in quantum capacitance due to hexagonal warping compared to the clean case, where both the in-plane magnetization and hexagonal warping are absent, is always negative, and increases in magnitude monotonically with the energy difference from the charge neutrality point. In contrast, the change in the quantum capacitance due to in-plane magnetization oscillates with the energy in general, except when a certain relation between the inter-surface coupling, out of plane Zeeman energy splitting and magnetic field strength is satisfied. In this special case, the quantum capacitance remains unchanged by the in-plane magnetization for all energies.

  8. Quantum Capacitance of a Topological Insulator-Ferromagnet Interface

    PubMed Central

    Siu, Zhuo Bin; Chowdhury, Debashree; Jalil, Mansoor B. A.; Basu, Banasri

    2017-01-01

    We study the quantum capacitance in a topological insulator thin film system magnetized in the in-plane direction in the presence of an out-of-plane magnetic field and hexagonal warping. To first order, the modification in quantum capacitance due to hexagonal warping compared to the clean case, where both the in-plane magnetization and hexagonal warping are absent, is always negative, and increases in magnitude monotonically with the energy difference from the charge neutrality point. In contrast, the change in the quantum capacitance due to in-plane magnetization oscillates with the energy in general, except when a certain relation between the inter-surface coupling, out of plane Zeeman energy splitting and magnetic field strength is satisfied. In this special case, the quantum capacitance remains unchanged by the in-plane magnetization for all energies. PMID:28337992

  9. A novel capacitive micro-accelerometer with grid strip capacitances and sensing gap alterable capacitances

    NASA Astrophysics Data System (ADS)

    Linxi, Dong; Jindan, Chen; Haixia, Yan; Weihong, Huo; Yongjie, Li; Lingling, Sun

    2009-03-01

    The comb capacitances fabricated by deep reactive ion etching (RIE) process have high aspect ratio which is usually smaller than 30: 1 for the complicated process factors, and the combs are usually not parallel due to the well-known micro-loading effect and other process factors, which restricts the increase of the seismic mass by increasing the thickness of comb to reduce the thermal mechanical noise and the decrease of the gap of the comb capacitances for increasing the sensitive capacitance to reduce the electrical noise. Aiming at the disadvantage of the deep RIE, a novel capacitive micro-accelerometer with grid strip capacitances and sensing gap alterable capacitances is developed. One part of sensing of inertial signal of the micro-accelerometer is by the grid strip capacitances whose overlapping area is variable and which do not have the non-parallel plate's effect caused by the deep RIE process. Another part is by the sensing gap alterable capacitances whose gap between combs can be reduced by the actuators. The designed initial gap of the alterable comb capacitances is relatively large to depress the effect of the maximum aspect ratio (30 : 1) of deep RIE process. The initial gap of the capacitance of the actuator is smaller than the one of the comb capacitances. The difference between the two gaps is the initial gap of the sensitive capacitor. The designed structure depresses greatly the requirement of deep RIE process. The effects of non-parallel combs on the accelerometer are also analyzed. The characteristics of the micro-accelerometer are discussed by field emission microscopy (FEM) tool ANSYS. The tested devices based on slide-film damping effect are fabricated, and the tested quality factor is 514, which shows that grid strip capacitance design can partly improve the resolution and also prove the feasibility of the designed silicon-glass anodically bonding process.

  10. Contact impedance of grounded and capacitive electrodes

    NASA Astrophysics Data System (ADS)

    Hördt, Andreas; Weidelt, Peter; Przyklenk, Anita

    2013-04-01

    The contact impedance of electrodes determines how much current can be injected into the ground for a given voltage. If the ground is very resistive, capacitive electrodes may be an alternative to galvanic coupling. The impedance of capacitive electrodes is often estimated with the assumption that the halfspace is an ideal conductor. Over resistive ground at high frequencies, however, the contact impedance will depend on the electrical properties, i.e. electrical conductivity and permittivity, of the subsurface. Here, we review existing equations for the resistance of a galvanically coupled, spherical electrode in a fullspace, and extend the theory to the general case of a sphere in a spherically layered fullspace. We then develop a method to calculate the impedance of a spherical disc over a homogeneous halfspace. We carry out modelling studies to demonstrate the consistency of the algorithms and to assess under which conditions the determination of the electrical parameters from the impedance may be feasible. For a capacitively coupled electrode, the common assumption of an ideally conducting fullspace (or halfspace) breaks down if the displacement currents in the fullspace become as large as the conduction currents. For a moderately resistive medium with 1000 Ωm this is the case for frequencies larger than 100 kHz. The transition from a galvanically coupled disc to a disc in the air is continuous as function of distance. However, depending on the electrical parameters and frequency, the impedance may vary by several orders of magnitude within a few nanometers distance or less. We derive a simple equation to assess under which conditions the impedance is independent of the electrode height, which may be important for determining subsurface permittivity and conductivity in cases where control on the exact geometry is difficult. Our theory is consistent with measured data obtained in a sandbox in the laboratory.

  11. Study on the Absolute Density and Translational Temperature of Si Atoms in Very High Frequency Capacitively Coupled SiH4 Plasma with Ar, N2, and H2 Dilution Gases

    NASA Astrophysics Data System (ADS)

    Ohta, Takayuki; Hori, Masaru; Ishida, Tetsuro; Goto, Toshio; Ito, Masafumi; Kawakami, Satoru

    2004-09-01

    The absolute densities and translational temperatures of Si atoms in very high frequency capacitively coupled SiH4 plasmas diluted with Ar, N2, and H2 gases were investigated by ultraviolet absorption spectroscopy with a ring dye laser and a hollow cathode lamp. It was found that the absolute density of Si atoms was of the order of 109-1010 cm-3 and the translational temperature of Si atoms ranged from 620 to 1130 K at a total pressure of 11 Pa, a dilution gas flow rate of 100 sccm, and a SiH4 flow rate of 0-15 sccm. The absolute densities and temperatures of Si atoms in plasma at an excitation frequency of 27 MHz were larger than those at 60 MHz under the conditions at the same electron density. Si atom heating was due to the energy of Si atoms released from the electron impact dissociation of SiHx (x=1--4). The translational temperatures of Si atoms in SiH4/Ar, SiH4/N2, and SiH4/H2 plasmas were evaluated to be 970, 1030, and 1130 K, respectively, at a frequency of 27 MHz, a SiH4 flow rate of 10 sccm, and a VHF power of 1500 W. The effect of Si atoms and SiH3 radicals on film deposition was investigated for SiH4/N2 in 27 MHz and 60 MHz plasmas. From the measurement using Fourier transform infrared absorption spectroscopy, the peak of the Si-H bond decreased and that of the N-H bond increased with increasing excitation frequency. Therefore, the film deposited at 60 MHz indicated a nitride-rich composition in comparison with that at 27 MHz. The contribution ratio of Si atoms to SiH3 radicals for film deposition in 27 MHz plasma was larger than that in 60 MHz plasma. These results are very important from the viewpoint of understanding neutral radical chemistries in the plasma and their related processing.

  12. Quantum capacitance in monolayers of silicene and related buckled materials

    NASA Astrophysics Data System (ADS)

    Nawaz, S.; Tahir, M.

    2016-02-01

    Silicene and related buckled materials are distinct from both the conventional two dimensional electron gas and the famous graphene due to strong spin orbit coupling and the buckled structure. These materials have potential to overcome limitations encountered for graphene, in particular the zero band gap and weak spin orbit coupling. We present a theoretical realization of quantum capacitance which has advantages over the scattering problems of traditional transport measurements. We derive and discuss quantum capacitance as a function of the Fermi energy and temperature taking into account electron-hole puddles through a Gaussian broadening distribution. Our predicted results are very exciting and pave the way for future spintronic and valleytronic devices.

  13. Estimation of the convergence order of rigorous coupled-wave analysis for binary gratings in optical critical dimension metrology

    NASA Astrophysics Data System (ADS)

    Liu, Shiyuan; Ma, Yuan; Chen, Xiuguo; Zhang, Chuanwei

    2012-08-01

    In most cases of optical critical dimension metrology, when applying rigorous coupled-wave analysis to optical modeling, a high order of Fourier harmonics is usually set up to guarantee the convergence of the final results. However, the total number of floating point operations grows dramatically as the truncation order increases. Therefore, it is critical to choose an appropriate order to obtain high computational efficiency without losing much accuracy in the meantime. We show that the convergence order associated with the structural and optical parameters is estimated through simulation. The results indicate that the convergence order is linear with the period of the sample when fixing the other parameters, both for planar diffraction and conical diffraction. The illuminated wavelength also affects the convergence of a final result. With further investigations concentrated on the ratio of illuminated wavelength to period, it is discovered that the convergence order decreases with the growth of the ratio, and when the ratio is fixed, convergence order jumps slightly, especially in a specific range of wavelength. This characteristic could be applied to estimate the optimum convergence order of given samples to obtain high computational efficiency.

  14. Binary Plutinos

    NASA Astrophysics Data System (ADS)

    Noll, Keith S.

    2015-08-01

    The Pluto-Charon binary was the first trans-neptunian binary to be identified in 1978. Pluto-Charon is a true binary with both components orbiting a barycenter located between them. The Pluto system is also the first, and to date only, known binary with a satellite system consisting of four small satellites in near-resonant orbits around the common center of mass. Seven other Plutinos, objects in 3:2 mean motion resonance with Neptune, have orbital companions including 2004 KB19 reported here for the first time. Compared to the Cold Classical population, the Plutinos differ in the frequency of binaries, the relative sizes of the components, and their inclination distribution. These differences point to distinct dynamical histories and binary formation processes encountered by Plutinos.

  15. 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)

  16. 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.

  17. 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.

  18. 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.

  19. 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.

  20. 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.

  1. Coevolution of binaries and circumbinary gaseous discs

    NASA Astrophysics Data System (ADS)

    Fleming, David P.; Quinn, Thomas R.

    2017-01-01

    The recent discoveries of circumbinary planets by Kepler raise questions for contemporary planet formation models. Understanding how these planets form requires characterizing their formation environment, the circumbinary protoplanetary disc and how the disc and binary interact and change as a result. The central binary excites resonances in the surrounding protoplanetary disc which drive evolution in both the binary orbital elements and in the disc. To probe how these interactions impact binary eccentricity and disc structure evolution, N-body smooth particle hydrodynamics simulations of gaseous protoplanetary discs surrounding binaries based on Kepler 38 were run for 104 binary periods for several initial binary eccentricities. We find that nearly circular binaries weakly couple to the disc via a parametric instability and excite disc eccentricity growth. Eccentric binaries strongly couple to the disc causing eccentricity growth for both the disc and binary. Discs around sufficiently eccentric binaries which strongly couple to the disc develop an m = 1 spiral wave launched from the 1:3 eccentric outer Lindblad resonance which corresponds to an alignment of gas particle longitude of periastrons. All systems display binary semimajor axis decay due to dissipation from the viscous disc.

  2. 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.

  3. 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.

  4. 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

  5. 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.

  6. Capacitance multiplier and filter synthesizing network

    NASA Technical Reports Server (NTRS)

    Kline, A. J. (Inventor)

    1974-01-01

    A circuit using a differential amplifier multiplies the capacitance of a discrete interating capacitor by (r sub 1 + R sub 2)/R sub 2, where R sub 1 and R sub 2 are values of discrete resistor coupling an input signal e sub 1 of the amplifier inputs. The output e sub 0 of the amplifier is fed back and added to the signal coupled by the resistor R sub 2 to the amplifier through a resistor of value R sub 1. A discrete resistor R sub x may be connected in series for a lag filter, and a discrete resistor may be connected in series with the capacitor for a lead-lag filter. Voltage dividing resistors R sub a and R sub b may be included in the feedback circuit of the amplifier output e sub o to independently adjust the circuit gain e sub i/e sub o.

  7. 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.

  8. The 2015 Decay of the Black Hole X-Ray Binary V404 Cygni: Robust Disk-jet Coupling and a Sharp Transition into Quiescence

    NASA Astrophysics Data System (ADS)

    Plotkin, R. M.; Miller-Jones, J. C. A.; Gallo, E.; Jonker, P. G.; Homan, J.; Tomsick, J. A.; Kaaret, P.; Russell, D. M.; Heinz, S.; Hodges-Kluck, E. J.; Markoff, S.; Sivakoff, G. R.; Altamirano, D.; Neilsen, J.

    2017-01-01

    We present simultaneous X-ray and radio observations of the black hole X-ray binary V404 Cygni at the end of its 2015 outburst. From 2015 July 11–August 5, we monitored V404 Cygni with Chandra, Swift, and NuSTAR in the X-ray, and with the Karl G. Jansky Very Large Array and the Very Long Baseline Array in the radio, spanning a range of luminosities that were poorly covered during its previous outburst in 1989 (our 2015 campaign covers 2× {10}33≲ {L}{{X}}≲ {10}34 {erg} {{{s}}}-1). During our 2015 campaign, the X-ray spectrum evolved rapidly from a hard photon index of {{Γ }}≈ 1.6 (at {L}{{X}}≈ {10}34 {erg} {{{s}}}-1) to a softer {{Γ }}≈ 2 (at {L}{{X}}≈ 3× {10}33 {erg} {{{s}}}-1). We argue that V404 Cygni reaching {{Γ }}≈ 2 marks the beginning of the quiescent spectral state, which occurs at a factor of ≈3–4 higher X-ray luminosity than the average pre-outburst luminosity of ≈ 8× {10}32 {erg} {{{s}}}-1. V404 Cygni falls along the same radio/X-ray luminosity correlation that it followed during its previous outburst in 1989, implying a robust disk-jet coupling. We exclude the possibility that a synchrotron-cooled jet dominates the X-ray emission in quiescence, leaving synchrotron self-Compton from either a hot accretion flow or from a radiatively cooled jet as the most likely sources of X-ray radiation, and/or particle acceleration along the jet becoming less efficient in quiescence. Finally, we present the first indications of correlated radio and X-ray variability on minute timescales in quiescence, tentatively measuring the radio emission to lag the X-ray by 15+/- 4 minute, suggestive of X-ray variations propagating down a jet with a length of <3.0 au.

  9. Preamplifiers for non-contact capacitive biopotential measurements.

    PubMed

    Peng, GuoChen; Ignjatovic, Zeljko; Bocko, Mark F

    2013-01-01

    Non-contact biopotential sensing is an attractive measurement strategy for a number of health monitoring applications, primarily the ECG and the EEG. In all such applications a key technical challenge is the design of a low-noise trans-impedance preamplifier for the typically low-capacitance, high source impedance sensing electrodes. In this paper, we compare voltage and charge amplifier designs in terms of their common mode rejection ratio, noise performance, and frequency response. Both amplifier types employ the same operational-transconductance amplifier (OTA), which was fabricated in a 0.35 um CMOS process. The results show that a charge amplifier configuration has advantages for small electrode-to-subject coupling capacitance values (less than 10 pF--typical of noncontact electrodes) and that the voltage amplifier configuration has advantages for electrode capacitances above 10 pF.

  10. Preamplifiers for non-contact capacitive biopotential measurements*

    PubMed Central

    Peng, GuoChen; Ignjatovic, Zeljko; Bocko, Mark F.

    2014-01-01

    Non-contact biopotential sensing is an attractive measurement strategy for a number of health monitoring applications, primarily the ECG and the EEG. In all such applications a key technical challenge is the design of a low-noise trans-impedance preamplifier for the typically low-capacitance, high source impedance sensing electrodes. In this paper, we compare voltage and charge amplifier designs in terms of their common mode rejection ratio, noise performance, and frequency response. Both amplifier types employ the same operational-transconductance amplifier (OTA), which was fabricated in a 0.35um CMOS process. The results show that a charge amplifier configuration has advantages for small electrode-to-subject coupling capacitance values (less than 10 pF - typical of noncontact electrodes) and that the voltage amplifier configuration has advantages for electrode capacitances above 10 pF. PMID:24109979

  11. Coherence properties of a capacitively-shunt flux qubit

    NASA Astrophysics Data System (ADS)

    Birenbaum, Jeffrey; Sears, Adam; Nugroho, Christopher; Gudmundsen, Ted; Welander, Paul; Yoder, Jonilyn; Kamal, Archana; Gustavsson, Simon; Kerman, Jamie; Oliver, William; Clarke, John

    2014-03-01

    Coherence times for typical flux qubits have plateaued at 5 - 10 μ s for T1 and 1 - 3 μ s for TRamsey. To achieve longer coherence times we study capacitively-shunted flux qubits using high-Q capacitors to individually shunt all four Josephson junctions (JJs). The additional shunt capacitance moves 90 + % of the qubit energy from the lossy capacitance of the JJs into the high-Q shunts while preserving an anharmonicity greater than 100 % and maintaining f01 capacitively-shunted flux qubit inductively coupled to a lumped-element readout resonator. The qubit junctions are deposited via aluminum e-beam evaporation using a bridgeless mask. We characterize the influence of qubit design parameters such as capacitance and geometry on the coherence time of the device. This research was funded in part by the Office of the Director of National Intelligence (ODNI), Intelligence Advanced Research Projects Activity (IARPA), through the Army Research Office.

  12. Capacitance and compressibility of heterostructures with strong electronic correlations

    NASA Astrophysics Data System (ADS)

    Steffen, Kevin; Frésard, Raymond; Kopp, Thilo

    2017-01-01

    Strong electronic correlations related to a repulsive local interaction suppress the electronic compressibility in a single-band model, and the capacitance of a corresponding metallic film is directly related to its electronic compressibility. Both statements may be altered significantly when two extensions to the system are implemented which we investigate here: (i) we introduce an attractive nearest-neighbor interaction V as antagonist to the repulsive onsite repulsion U , and (ii) we consider nanostructured multilayers (heterostructures) assembled from two-dimensional layers of these systems. We determine the respective total compressibility κ and capacitance C of the heterostructures within a strong coupling evaluation, which builds on a Kotliar-Ruckenstein slave-boson technique. Whereas the capacitance C (n ) for electronic densities n close to half-filling is suppressed, illustrated by a correlation induced dip in C (n ) , it may be appreciably enhanced close to a van Hove singularity. Moreover, we show that the capacitance may be a nonmonotonic function of U close to half-filling for both attractive and repulsive V . The compressibility κ can differ from C substantially, as κ is very sensitive to internal electrostatic energies which in turn depend on the specific setup of the heterostructure. In particular, we show that a capacitor with a polar dielectric has a smaller electronic compressibility and is more stable against phase separation than a standard nonpolar capacitor with the same capacitance.

  13. Hyaluronic acid as capacitation inductor: metabolic changes and membrane-associated adenylate cyclase regulation.

    PubMed

    Fernández, S; Córdoba, M

    2014-12-01

    The aim of this research was to study the effect of hyaluronic acid on bovine cryopreserved spermatozoa compared with heparin as regards the variation of capacitation induction, cellular oxidative metabolism and intracellular signal induced by membrane-associated adenylate cyclase to propose hyaluronic acid as a capacitation inductor. Heparin or hyaluronic acid and lysophosphatidylcholine were used to induce sperm capacitation and acrosome reaction, respectively. 2',5'-dideoxyadenosine was used as a membrane-associated adenylate cyclase inhibitor. The highest percentages of capacitated spermatozoa and live spermatozoa with acrosome integrity were obtained by incubating sperm for 60 min using 1000 μg/ml hyaluronic acid. In these conditions, capacitation induced by hyaluronic acid was lower compared with heparin; nonetheless both glycosaminoglycans promote intracellular changes that allow true acrosome reaction in vitro induced by lysophosphatidylcholine in bovine spermatozoa. Oxygen consumption in heparin-capacitated spermatozoa was significantly higher than in hyaluronic acid-treated spermatozoa. With all treatments, mitochondrial coupling was observed when a specific uncoupler of the respiratory chain was added. The inhibition of membrane-associated adenylate cyclase significantly blocked capacitation induction produced by hyaluronic acid, maintaining a basal sperm oxygen uptake in contrast to heparin effect in which both sperm parameters were inhibited, suggesting that the membrane-associated adenylate cyclase activation is involved in the intracellular signal mechanisms induced by both capacitation inductors, but only regulates mitochondrial oxidative phosphorylation in heparin-capacitated spermatozoa.

  14. 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.

  15. 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

  16. 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.

  17. Unified capacitance modelling of MOSFETs

    NASA Astrophysics Data System (ADS)

    Johannessen, O. G.; Fjeldly, T. A.; Ytterdal, T.

    1994-01-01

    A unified physics based capacitance model for MOSFETs suitable for implementation in circuit simulators is presented. This model is based on the charge conserving, so-called Meyer-like approach proposed by Turchetti et al., and utilizes a unified charge control model to assure a continuous description of the MOSFET capacitances both above and below threshold. The capacitances associated with the model are comparable to those of the well-known BSIM model in the above-threshold regime, but it is more precise in the description of near-threshold and subthreshold behaviour. Moreover, the discontinuities at the transitions between the various regimes of operation are removed. The present modelling scheme was implemented in our circuit simulator AIM-Spice, and simulations of the dynamic behaviour of various demanding benchmark circuits clearly reveal its superiority over simulations using the simple Meyer model.

  18. Bioenergetics of Mammalian Sperm Capacitation

    PubMed Central

    Ferramosca, Alessandra; Zara, Vincenzo

    2014-01-01

    After ejaculation, the mammalian male gamete must undergo the capacitation process, which is a prerequisite for egg fertilization. The bioenergetics of sperm capacitation is poorly understood despite its fundamental role in sustaining the biochemical and molecular events occurring during gamete activation. Glycolysis and mitochondrial oxidative phosphorylation (OXPHOS) are the two major metabolic pathways producing ATP which is the primary source of energy for spermatozoa. Since recent data suggest that spermatozoa have the ability to use different metabolic substrates, the main aim of this work is to present a broad overview of the current knowledge on the energy-producing metabolic pathways operating inside sperm mitochondria during capacitation in different mammalian species. Metabolism of glucose and of other energetic substrates, such as pyruvate, lactate, and citrate, is critically analyzed. Such knowledge, besides its obvious importance for basic science, could eventually translate into the development of novel strategies for treatment of male infertility, artificial reproduction, and sperm selection methods. PMID:24791005

  19. High on/off capacitance ratio RF MEMS capacitive switches

    NASA Astrophysics Data System (ADS)

    Wei, Hao; Deng, Zhongliang; Guo, Xubing; Wang, Yucheng; Yang, Hongtao

    2017-05-01

    In this paper, high on/off capacitance ratio radio frequency micro-electro-mechanical-systems (RF MEMS) switches are designed, fabricated, measured and analyzed. Two types of RF MEMS switches, a shunt switch with a contact point and an inline switch without a contact point, are presented. Metal-insulator-metal (MIM) fixed capacitors are used in the MEMS switches. The electrode topologies of RF MEMS switches are analyzed. The parameter λ is defined to describe the relationship between the capacitance ratio, the height of the beam and the actuation voltage. The measured results indicate that, for MEMS switch #1 with a contact point and gap of 1 µm, the insertion loss is better than 0.64 dB up to 40 GHz, and the isolation is more than 20 dB from 11.28 to 30.38 GHz with an actuation voltage of 42 V. For the inline MEMS with a displacement of 1.5 µm, the insertion loss is better than 0.56 dB up to 40 GHz, and the isolation is more than 20 dB from 4.45 to 30.48 GHz with an actuation voltage of 36 V. Circuit models and measured results of the proposed MEMS switches show good agreement. From the fitted results, the on/off capacitance ratio is ~227 for the MEMS switch #1 and ~313 for the MEMS switch #2, respectively. Compared with traditional MEMS capacitive switches with dielectric material Si3N4 and a relatively lower gap (1.5 µm), the proposed MEMS switches exhibit high on/off capacitance ratios.

  20. 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

    Rohman, Abdul; Ariani, Rizka

    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 (R (2), 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 R (2) 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 R (2) 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.

  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. Linearization techniques for capacitive sensors

    NASA Astrophysics Data System (ADS)

    Kar, Barun K.; Joseph, Eric

    1995-09-01

    Capacitive sensors are essential elements in many instrumentation circuits. The widespread use of these instruments and the need for integrating sensors on the same chip as the signal processing circuitry has motivated the developement of linearization techniques for the sensor output. Presented here are four methods which can be used to 'linearize' the essentially nonlinear nature of capacitive transducers. Described first is the polynomial linearization scheme, in which the Taylor series expansion of the sensor output is linearized by Khachab's method. An improvement in accuracy is obtained by the direct linearization scheme which scales the sensor output by the nonlinear denominator. Though this scheme is useful in cases where the signal processing circuitry must be separated from the interface circuitry, the hardware requirements are pretty intense. An alternative approach is the Summer-Divide scheme, wherein the difference and the sum of the top and bottom capacitances are ratioed to yield the linearized output. The last method is the constant charge injection scheme. Here a constant charge is put on top of the top of the plates and the subsequent voltages are differenced to yield a linear output. Nonlinearity associated with parasitic capacitances can be easily removed by feedback schemes.

  3. Capacitive Proximity Sensor Has Longer Range

    NASA Technical Reports Server (NTRS)

    Vranish, John M.

    1992-01-01

    Capacitive proximity sensor on robot arm detects nearby object via capacitive effect of object on frequency of oscillator. Sensing element part of oscillator circuit operating at about 20 kHz. Total capacitance between sensing element and ground constitutes tuning capacitance of oscillator. Sensor circuit includes shield driven by replica of alternating voltage applied to sensing element. Driven shield concentrates sensing electrostatic field in exterior region to enhance sensitivity to object. Sensitivity and dynamic range has corresponding 12-to-1 improvement.

  4. Systematic interpretation of differential capacitance data

    NASA Astrophysics Data System (ADS)

    Gavish, Nir; Promislow, Keith

    2015-07-01

    Differential capacitance (DC) data have been widely used to characterize the structure of electrolyte solutions near charged interfaces and as experimental validation of models for electrolyte structure. Fixing a large class of models of electrolyte free energy that incorporate finite-volume effects, a reduction is identified which permits the identification of all free energies within that class that return identical DC data. The result is an interpretation of DC data through the equivalence classes of nonideality terms, and associated boundary layer structures, that cannot be differentiated by DC data. Specifically, for binary salts, DC data, even if measured over a range of ionic concentrations, are unable to distinguish among models which exhibit charge asymmetry, charge reversal, and even ion crowding. The reduction applies to capacitors which are much wider than the associated Debye length and to finite-volume terms that are algebraic in charge density. However, within these restrictions the free energy is shown to be uniquely identified if the DC data are supplemented with measurements of the excess chemical potential of the system in the bulk state.

  5. Active Targets For Capacitive Proximity Sensors

    NASA Technical Reports Server (NTRS)

    Jenstrom, Del T.; Mcconnell, Robert L.

    1994-01-01

    Lightweight, low-power active targets devised for use with improved capacitive proximity sensors described in "Capacitive Proximity Sensor Has Longer Range" (GSC-13377), and "Capacitive Proximity Sensors With Additional Driven Shields" (GSC-13475). Active targets are short-distance electrostatic beacons; they generate known alternating electro-static fields used for alignment and/or to measure distances.

  6. Capacitance Property of a Resonant Tunneling Diode

    NASA Astrophysics Data System (ADS)

    Sheng, Hanyu; Chua, Soo-Jin; Sinkkonen, Juha

    A simple capacitance formula based on a semiclassical electron transport theory is given. The results show that the charges stored in the quantum well of a resonant tunneling diode have a considerable effect on the capacitance in the resonant region. The calculated capacitance is consistent with the experimental results.

  7. 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.

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

    NASA Astrophysics Data System (ADS)

    Levi, Michele; Steinhoff, Jan

    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.

  9. 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.

  10. 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.

  11. Quantum Capacitance in Topological Insulators

    PubMed Central

    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. PMID:22993694

  12. Flexible Framework for Capacitive Sensing

    NASA Technical Reports Server (NTRS)

    Woodard, Stanley E. (Inventor); Taylor, Bryant D. (Inventor)

    2006-01-01

    A flexible framework supports electrically-conductive elements in a capacitive sensing arrangement. Identical frames are arranged end-to-end with adjacent frames being capable of rotational movement there between. Each frame has first and second passages extending therethrough and parallel to one another. Each of the first and second passages is adapted to receive an electrically-conductive element therethrough. Each frame further has a hollowed-out portion for the passage of a fluent material therethrough. The hollowed-out portion is sized and shaped to provide for capacitive sensing along a defined region between the electrically-conductive element in the first passage and the electrically-conductive element in the second passage.

  13. Impedance matching in RF excited fast axial flow CO2 laser: The role of the capacitance due to laser head

    NASA Astrophysics Data System (ADS)

    Bhagat, M. S.; Biswas, A. K.; Rana, L. B.; Kukreja, L. M.

    2012-10-01

    Impedance matching in an indigenously developed 2 kW RF-excited fast axial flow (RF-FAF) CO2 laser was seen to be significantly influenced by the capacitance formed between the laser head and the electrodes. We find in the published literature that this capacitance is generally assumed to be negligible while designing the matching network in the RF-FAF CO2 lasers. It is shown that this capacitance could have a significant value and consequently would modify the design of the matching network remarkably for a specific laser design studied in the present case. The widely used discharge load model for capacitively coupled RF (CCRF) discharge excited CO2 laser plasma is extended to include this capacitance. The method of measurement of this capacitance using a bridge and the ANSYS software based simulation of its formation due to the laser head structure are discussed.

  14. Capacitive de-ionization electrode

    DOEpatents

    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.

  15. 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.

  16. A Micro Dynamically Tuned Gyroscope with Adjustable Static Capacitance

    PubMed Central

    Xia, Dunzhu; Yu, Cheng; Kong, Lun

    2013-01-01

    This paper presents a novel micro dynamically tuned gyroscope (MDTG) with adjustable static capacitance. First, the principle of MDTG is theoretically analyzed. Next, some simulations under the optimized structure parameters are given as a reference for the mask design of the rotor wafer and electrode plates. As two key components, the process flows of the rotor wafer and electrode plates are described in detail. All the scanning electron microscopy (SEM) photos show that the fabrication process is effective and optimized. Then, an assembly model is designed for the static capacitance adjustable MDTG, whose static capacitance can be changed by rotating the lower electrode plate support and substituting gasket rings of different thicknesses. Thus, the scale factor is easily changeable. Afterwards, the digitalized closed-loop measurement circuit is simulated. The discrete correction and decoupling modules are designed to make the closed-loop stable and cross-coupling effect small. The dual axis closed-loop system bandwidths can reach more than 60 Hz and the dual axis scale factors are completely symmetrical. All the simulation results demonstrate the proposed fabrication of the MDTG can meet the application requirements. Finally, the paper presents the test results of static and dynamic capacitance values which are consistent with the simulation values. PMID:23389347

  17. 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.

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

    SciTech Connect

    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.-

  19. Planetary systems in binaries

    NASA Astrophysics Data System (ADS)

    Takeda, Genya

    In this thesis we investigate the orbital evolution of planets in binaries. Unlike our own Solar System, at least one out of five planetary systems known to date is associated with additional stellar companions. Despite their large distances from the planetary systems, these stellar companions play an important role in significantly altering the planetary architecture over very long timescales. Most of the planets in binaries are found in hierarchical configurations in which a planet orbits around a component of a wide stellar binary. The evolution of such hierarchical triples has been analytically understood through the framework of the Kozai mechanism, in which the orbital eccentricity of a planet secularly grows through angular momentum exchange with the stellar companion. The aim of our first study is to investigate the global effect of stellar companions in exciting planetary eccentricities through the Kozai mechanism, using synthetic eccentricity distributions computed numerically from various initial assumptions motivated by observational studies. As inferred from observations and theoretical planet formation simulations, newly formed planetary systems are more likely to be oligarchic, containing multiple giant planets. However, the long-term evolution of gravitationally coupled planets perturbed by a stellar companion has been little understood in the previous studies. From a large ensemble of numerical integrations of double-planet systems in binaries, we have found that there are various evolutionary classes of multiple planets in binaries compared to simple hierarchical triple systems containing only one planet. Using the Kozai mechanism and the Laplace-Lagrange secular theory, we also provide analytic criteria that can readily predict the secular evolutionary behavior of a pair of planetary orbits in binaries. In the last part of this thesis we discuss an alternative channel of planetary migration induced by a combined effect of dissipative tidal forces

  20. Capacitance variation measurement method with a continuously variable measuring range for a micro-capacitance sensor

    NASA Astrophysics Data System (ADS)

    Lü, Xiaozhou; Xie, Kai; Xue, Dongfeng; Zhang, Feng; Qi, Liang; Tao, Yebo; Li, Teng; Bao, Weimin; Wang, Songlin; Li, Xiaoping; Chen, Renjie

    2017-10-01

    Micro-capacitance sensors are widely applied in industrial applications for the measurement of mechanical variations. The measurement accuracy of micro-capacitance sensors is highly dependent on the capacitance measurement circuit. To overcome the inability of commonly used methods to directly measure capacitance variation and deal with the conflict between the measurement range and accuracy, this paper presents a capacitance variation measurement method which is able to measure the output capacitance variation (relative value) of the micro-capacitance sensor with a continuously variable measuring range. We present the principles and analyze the non-ideal factors affecting this method. To implement the method, we developed a capacitance variation measurement circuit and carried out experiments to test the circuit. The result shows that the circuit is able to measure a capacitance variation range of 0–700 pF linearly with a maximum relative accuracy of 0.05% and a capacitance range of 0–2 nF (with a baseline capacitance of 1 nF) with a constant resolution of 0.03%. The circuit is proposed as a new method to measure capacitance and is expected to have applications in micro-capacitance sensors for measuring capacitance variation with a continuously variable measuring range.

  1. 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

  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. Modeling electromagnetic effects in capacitive discharges

    NASA Astrophysics Data System (ADS)

    Lee, Insook; Graves, D. B.; Lieberman, M. A.

    2008-02-01

    We present a self-consistent two-dimensional axisymmetric model and simulation strategy to predict radial plasma uniformity in large-area high-frequency (up to 200 MHz) capacitive discharges of argon gas in the pressure range 2-150 mTorr. The model couples Maxwell equations, fluid plasma equations and a sheath model with stochastic heating effects taken into account, solving the equations using the finite element method. Electromagnetic effects (e.g. standing wave and skin effects) as well as the electrostatic edge effect are captured in the simulation, in good agreement with recent experiments. The model highlights differences between the edge effect and the skin effect, both of which can cause strong plasma production near the radial reactor edge. At higher frequencies and high pressures, we observe the 'stop band' where waves are highly damped as they propagate from the discharge edge into the center. We determine the transition from global-to-local power deposition as the pressure varies. An electrode asymmetry with a grounded reactor radial edge is found to suppress undesirable edge effects. For radial plasma uniformity, it is essential to consider the balancing of the standing wave effect (maximal at the reactor center) with the skin effect (maximal near the radial reactor edge), together with their coupling to the edge effect, which can be obtained by a choice of robust reactor design geometry and driving frequency, over the range of process parameter operating windows to be used.

  4. Capacitance enhancement via electrode patterning

    NASA Astrophysics Data System (ADS)

    Ho, Tuan A.; Striolo, Alberto

    2013-11-01

    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.

  5. 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

  6. 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.

  7. 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.

  8. 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.

  9. Versatile and compact capacitive dilatometer

    SciTech Connect

    Schmiedeshoff, G. M.; Lounsbury, A. W.; Luna, D. J.; Tracy, S. J.; Schramm, A. J.; Tozer, S. W.; Correa, V. F.; Hannahs, S. T.; Murphy, T. P.; Palm, E. C.; Lacerda, A. H.; Bud'ko, S. L.; Canfield, P. C.; Smith, J. L.; Lashley, J. C.; Cooley, J. C.

    2006-12-15

    We describe the design, construction, calibration, and operation of a relatively simple differential capacitive dilatometer suitable for measurements of thermal expansion and magnetostriction from 300 to below 1 K with a low-temperature resolution of about 0.05 A ring . The design is characterized by an open architecture permitting measurements on small samples with a variety of shapes. Dilatometers of this design have operated successfully with a commercial physical property measurement system, with several types of cryogenic refrigeration systems, in vacuum, in helium exchange gas, and while immersed in liquid helium (magnetostriction only) to temperatures of 30 mK and in magnetic fields to 45 T.

  10. Microfluidic electromanipulation with capacitive detection for the mechanical analysis of cells

    PubMed Central

    Ferrier, G. A.; Hladio, A. N.; Thomson, D. J.; Bridges, G. E.; Hedayatipoor, M.; Olson, S.; Freeman, M. R.

    2008-01-01

    The mechanical behavior of cells offers insight into many aspects of their properties. We propose an approach to the mechanical analysis of cells that uses a combination of electromanipulation for stimulus and capacitance for sensing. To demonstrate this approach, polystyrene spheres and yeast cells flowing in a 25 μm×100 μm microfluidic channel were detected by a perpendicular pair of gold thin film electrodes in the channel, spaced 25 μm apart. The presence of cells was detected by capacitance changes between the gold electrodes. The capacitance sensor was a resonant coaxial radio frequency cavity (2.3 GHz) coupled to the electrodes. The presence of yeast cells (Saccharomyces cerevisiae) and polystyrene spheres resulted in capacitance changes of approximately 10 and 100 attoFarad (aF), respectively, with an achieved capacitance resolution of less than 2 aF in a 30 Hz bandwidth. The resolution is better than previously reported in the literature, and the capacitance changes are in agreement with values estimated by finite element simulations. Yeast cells were trapped using dielectrophoretic forces by applying a 3 V signal at 1 MHz between the electrodes. After trapping, the cells were displaced using amplitude and frequency modulated voltages to produce modulated dielectrophoretic forces. Repetitive displacement and relaxation of these cells was observed using both capacitance and video microscopy. PMID:19693366

  11. Aspheric Surface Measurement Using Capacitive Sensors

    PubMed Central

    Yuan, Daocheng; Zhao, Huiying; Tao, Xin; Li, Shaobo; Zhu, Xueliang; Zhang, Chupeng

    2017-01-01

    This paper proposes a new method for the measurement of spherical coordinates by using capacitive sensors as a non-contact probe solution of measurement of aspheric surfaces. The measurement of the average effect of the capacitive probe and the influence of capacitive probe tilting were studied with respect to an eccentric spherical surface. Based on the tested characteristic curve of the average effect of the sphere and probe, it was found that nonlinear and linear compensation resulted in high measurement accuracy. The capacitance probe was found to be trying to fulfill a need for performing nm-level precision measurement of aspheric electromagnetic surfaces. PMID:28604613

  12. Nucleotide capacitance calculation for DNA sequencing

    SciTech Connect

    Lu, Jun-Qiang; Zhang, Xiaoguang

    2008-01-01

    Using a first-principles linear response theory, the capacitance of the DNA nucleotides, adenine, cytosine, guanine and thymine, are calculated. The difference in the capacitance between the nucleotides is studied with respect to conformational distortion. The result suggests that although an alternate current capacitance measurement of a single-stranded DNA chain threaded through a nano-gap electrodes may not sufficient to be used as a stand alone method for rapid DNA sequencing, the capacitance of the nucleotides should be taken into consideration in any GHz-frequency electric measurements and may also serve as an additional criterion for identifying the DNA sequence.

  13. Detection of Telomerase Activity Using Capacitance Measurements

    NASA Astrophysics Data System (ADS)

    Kang, Bong Keun; Lee, Ri Mi; Choi, Ahmi; Jung, Hyo-Il; Yoo, Kyung-Hwa

    2007-03-01

    Telomerase activity has been found in about 85% cancer cells, while no activity observed in normal cells, so that telomerase has been proposed as a marker for cancer detection. Here, we describe electrical detection of telomerase activity using capacitance measurements. We have investigated the length dependence of capacitance on DNA solutions and found that the capacitance of DNA solutions were dependent on the DNA length. In addition, upon adding telomerase into the solution of telomeric substrate primer, the capacitance was observed to change as a function of time due to the telomeric elongation. These results suggest that this novel nanosensor may be used for rapid detection of telomerase activity.

  14. Correlation analysis of waves above a capacitive plasma applicator.

    PubMed

    Gekelman, W; Barnes, M; Vincena, S; Pribyl, P

    2009-07-24

    Capacitively coupled plasma glow discharges have been extensively used for materials processing in numerous industrial applications. Considerable research has been performed on plasma sheaths and standing waves over a capacitive applicator, which typically holds the processed substrate (e.g., a semiconductor wafer). In this work, we demonstrate for the first time the existence of normal modes in electric potential analogous to the vibrational modes in circular membranes and plates. These modes are exhibited through cross spectral analysis of the plasma potential measured with an emissive probe at 208 spatial positions and sampled at 1 GHz. These modes exist at several frequencies and are described by a series of Bessel functions. The data further suggests a nonlinear interaction between modes of different frequencies.

  15. Correlation Analysis of Waves above a Capacitive Plasma Applicator

    SciTech Connect

    Gekelman, W.; Vincena, S.; Pribyl, P.; Barnes, M.

    2009-07-24

    Capacitively coupled plasma glow discharges have been extensively used for materials processing in numerous industrial applications. Considerable research has been performed on plasma sheaths and standing waves over a capacitive applicator, which typically holds the processed substrate (e.g., a semiconductor wafer). In this work, we demonstrate for the first time the existence of normal modes in electric potential analogous to the vibrational modes in circular membranes and plates. These modes are exhibited through cross spectral analysis of the plasma potential measured with an emissive probe at 208 spatial positions and sampled at 1 GHz. These modes exist at several frequencies and are described by a series of Bessel functions. The data further suggests a nonlinear interaction between modes of different frequencies.

  16. 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…

  17. High temperature capacitive strain gage

    NASA Astrophysics Data System (ADS)

    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.

  18. 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.

  19. 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.

  20. 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.