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Sample records for plasma quench process

  1. Titanium Metal Powder Production by the Plasma Quench Process

    SciTech Connect

    R. A. Cordes; A. Donaldson

    2000-09-01

    The goals of this project included the scale-up of the titanium hydride production process to a production rate of 50 kg/hr at a purity level of 99+%. This goal was to be achieved by incrementally increasing the production capability of a series of reactor systems. This methodic approach was designed to allow Idaho Titanium Technologies to systematically address the engineering issues associated with plasma system performance, and powder collection system design and performance. With quality powder available, actual fabrication with the titanium hydride was to be pursued. Finally, with a successful titanium production system in place, the production of titanium aluminide was to be pursued by the simultaneously injection of titanium and aluminum precursors into the reactor system. Some significant accomplishments of the project are: A unique and revolutionary torch/reactor capable of withstanding temperatures up to 5000 C with high thermal efficiency has been operated. The dissociation of titanium tetrachloride into titanium powder and HC1 has been demonstrated, and a one-megawatt reactor potentially capable of producing 100 pounds per hour has been built, but not yet operated at the powder level. The removal of residual subchlorides and adsorbed HC1 and the sintering of powder to form solid bodies have been demonstrated. The production system has been operated at production rates up to 40 pounds per hour. Subsequent to the end of the project, Idaho Titanium Technologies demonstrated that titanium hydride powder can indeed be sintered into solid titanium metal at 1500 C without sintering aids.

  2. Coal liquefaction quenching process

    DOEpatents

    Thorogood, Robert M.; Yeh, Chung-Liang; Donath, Ernest E.

    1983-01-01

    There is described an improved coal liquefaction quenching process which prevents the formation of coke with a minimum reduction of thermal efficiency of the coal liquefaction process. In the process, the rapid cooling of the liquid/solid products of the coal liquefaction reaction is performed without the cooling of the associated vapor stream to thereby prevent formation of coke and the occurrence of retrograde reactions. The rapid cooling is achieved by recycling a subcooled portion of the liquid/solid mixture to the lower section of a phase separator that separates the vapor from the liquid/solid products leaving the coal reactor.

  3. Plasma quench production of titanium from titanium tetrachloride

    SciTech Connect

    Sears, J.W.

    1994-10-01

    This project, Plasma Quench Production of Titanium from Titanium Tetrachloride, centers on developing a technique for rapidly quenching the high temperature metal species and preventing back reactions with the halide. The quenching technique chosen uses the temperature drop produced in a converging/diverging supersonic nozzle. The rapid quench provided by this nozzle prevents the back reaction of the halide and metal. The nature of the process produces nanosized particles (10 to 100 nm). The powders are collected by cyclone separators, the hydrogen flared, and the acid scrubbed. Aluminum and titanium powders have been produced in the laboratory-scale device at 1 gram per hour. Efforts to date to scale up this process have not been successful.

  4. Cryogenic Quenching Process for Electronic Part Screening

    NASA Technical Reports Server (NTRS)

    Sheldon, Douglas J.; Cressler, John

    2011-01-01

    The use of electronic parts at cryogenic temperatures (less than 100 C) for extreme environments is not well controlled or developed from a product quality and reliability point of view. This is in contrast to the very rigorous and well-documented procedures to qualify electronic parts for mission use in the 55 to 125 C temperature range. A similarly rigorous methodology for screening and evaluating electronic parts needs to be developed so that mission planners can expect the same level of high reliability performance for parts operated at cryogenic temperatures. A formal methodology for screening and qualifying electronic parts at cryogenic temperatures has been proposed. The methodology focuses on the base physics of failure of the devices at cryogenic temperatures. All electronic part reliability is based on the bathtub curve, high amounts of initial failures (infant mortals), a long period of normal use (random failures), and then an increasing number of failures (end of life). Unique to this is the development of custom screening procedures to eliminate early failures at cold temperatures. The ability to screen out defects will specifically impact reliability at cold temperatures. Cryogenic reliability is limited by electron trap creation in the oxide and defect sites at conductor interfaces. Non-uniform conduction processes due to process marginalities will be magnified at cryogenic temperatures. Carrier mobilities change by orders of magnitude at cryogenic temperatures, significantly enhancing the effects of electric field. Marginal contacts, impurities in oxides, and defects in conductor/conductor interfaces can all be magnified at low temperatures. The novelty is the use of an ultra-low temperature, short-duration quenching process for defect screening. The quenching process is designed to identify those defects that will precisely (and negatively) affect long-term, cryogenic part operation. This quenching process occurs at a temperature that is at least

  5. Flame quenching process in cavity based on model scramjet combustor

    NASA Astrophysics Data System (ADS)

    Pan, Yu; Lei, Jing; Liang, Jian-Han; Liu, Wei-Dong; Wang, Zhen-Guo

    2012-02-01

    The flame quenching process in combustors was observed by high speed camera and Schlieren system, at the inflow conditions of Ma = 2.64, T 0 = 1 483 K, P 0 = 1.65MPa, T = 724K and P = 76.3 kPa. Changing process of the flame and shock structure in the combustor was clearly observed. The results revealed that the precombustion shock disappeared accompanied with the process in which the flame was blown out and withdrawed from the mainflow into the cavity and vanished after a short while. The time of quenching process was extended by the cavity flame holder, and the ability of flame holding was enhanced by arranging more cavities in the downstream as well. The flame was blown from the upstream to the downstream, so the flame in the downstream of the cavity was quenched out later than that in the upstream.

  6. Temperature Dependence of Nitro-Quenching by Atmospheric-Pressure Plasma

    NASA Astrophysics Data System (ADS)

    Mitani, Masaki; Ichiki, Ryuta; Iwakiri, Yutaro; Akamine, Shuichi; Kanazawa, Seiji

    2015-09-01

    A lot of techniques exist as the hardening method of steels, such as nitriding, carburizing and quenching. However, low-alloy steels cannot be hardened by nitriding because hardening by nitriding requires nitride precipitates of special alloy elements such as rare metals. Recently, nitro-quenching (NQ) was developed as a new hardening process, where nitrogen invokes martensitic transformation instead of carbon. NQ is adaptable to hardening low-alloy steels because it does not require alloy elements. In industrial NQ, nitrogen diffusion into steel surface is operated in high temperature ammonia gas. As a new technology, we have developed surface hardening of low-alloy steel by NQ using an atmospheric-pressure plasma. Here the pulsed-arc plasma jet with nitrogen/hydrogen gas mixture is sprayed onto steel surface and then water quench the sample. As a result, the surface of low-alloy steel was partially hardened up to 800 Hv by producing iron-nitrogen martensite. However, the hardness profile is considerably non-uniform. We found that the non-uniform hardness profile can be controlled by changing the treatment gap, the gap between the jet nozzle and the sample surface. Eventually, we succeeded in hardening a targeted part of steel by optimizing the treatment gap. Moreover, we propose the mechanism of non-uniform hardness.

  7. Plasma quench technology for natural gas conversion applications

    SciTech Connect

    Detering, B.A.; Kong, P.C.; Thomas, C.P.

    1995-07-01

    This paper describes the experimental demonstration of a process for direct conversion of methane to acetylene in a thermal plasma. The process utilizes a thermal plasma to dissociate methane and form an equilibrium mixture of acetylene followed by a supersonic expansion of the hot gas to preserve the produced acetylene in high yield. The high translational velocities and rapid cooling result in an overpopulation of atomic hydrogen which persists throughout the expansion process. The presence of atomic hydrogen shifts the equilibrium composition by inhibiting complete pyrolysis of methane and acetylene to solid carbon. This process has the potential to reduce the cost of producing acetylene from natural gas. Acetylene and hydrogen produced by this process could be used directly as industrial gases, building blocks for synthesis of industrial chemicals, or oligomerized to long chain liquid hydrocarbons for use as fuels. This process produces hydrogen and ultrafine carbon black in addition to acetylene.

  8. Modified Methodology for the Quench Temperature Selection in Quenching and Partitioning (Q&P) Processing of Steels

    NASA Astrophysics Data System (ADS)

    Seo, Eun Jung; Cho, Lawrence; De Cooman, Bruno C.

    2016-08-01

    The original method to select the optimum quench temperature for quenching and partitioning (Q&P) processing aims to determine the quench temperature which yields a maximum volume fraction of retained austenite. In the present study, the original method was reviewed and refined by comparison with experimental results. The proposed methodology is based on the use of a modified Koistinen-Marburger equation for the kinetics of the athermal martensite transformation of steels containing C, Mn, Si, Cr, and B.

  9. Numerical Analysis of Heat Transfer During Quenching Process

    NASA Astrophysics Data System (ADS)

    Madireddi, Sowjanya; Krishnan, Krishnan Nambudiripad; Reddy, Ammana Satyanarayana

    2016-06-01

    A numerical model is developed to simulate the immersion quenching process of metals. The time of quench plays an important role if the process involves a defined step quenching schedule to obtain the desired characteristics. Lumped heat capacity analysis used for this purpose requires the value of heat transfer coefficient, whose evaluation requires large experimental data. Experimentation on a sample work piece may not represent the actual component which may vary in dimension. A Fluid-Structure interaction technique with a coupled interface between the solid (metal) and liquid (quenchant) is used for the simulations. Initial times of quenching shows boiling heat transfer phenomenon with high values of heat transfer coefficients (5000-2.5 × 105 W/m2K). Shape of the work piece with equal dimension shows less influence on the cooling rate Non-uniformity in hardness at the sharp corners can be reduced by rounding off the edges. For a square piece of 20 mm thickness, with 3 mm fillet radius, this difference is reduced by 73 %. The model can be used for any metal-quenchant combination to obtain time-temperature data without the necessity of experimentation.

  10. Synthesis of Ozone at Atmospheric Pressure by a Quenched Induction-Coupled Plasma Torch

    SciTech Connect

    A. Blutke; B.C. Stratton; D.R. Mikkelsen; J. Vavruska; R. Knight

    1998-01-01

    The technical feasibility of using an induction-coupled plasma (ICP) torch to synthesize ozone at atmospheric pressure is explored. Ozone concentrations up to ~250 ppm were produced using a thermal plasma reactor system based on an ICP torch operating at 2.5 MHz and ~11 kVA with an argon/oxygen mixture as the plasma-forming gas. A gaseous oxygen quench formed ozone by rapid mixing of molecular oxygen with atomic oxygen produced by the torch. The ozone concentration in the reaction chamber was measured by Fourier Transform infrared (FTIR) spectroscopy over a wide range of experimental configurations. The geometry of the quench gas flow, the quench flow velocity, and the quench flow rate played important roles in determining the ozone concentration. The ozone concentration was sensitive to the torch RF power, but was insensitive to the torch gas flow rates. These observations are interpreted within the framework of a simple model of ozone synthesis.

  11. Universality in the Equilibration of Quenched Yukawa One Component Plasmas

    NASA Astrophysics Data System (ADS)

    Langin, Thomas; McQuillen, Patrick; Strickler, Trevor; Maksimovic, Nikola; Pohl, Thomas; Killian, Thomas

    2015-11-01

    We study the equilibration of a Yukawa One Component Plasma (OCP) after a rapid change in the screening parameter from κ0 = ∞ to κf (n ,Te) , which is realized by photoionizing a laser cooled (T ~ 10 mK), uncorrelated gas of 88Sr atoms with density n between 1014 m-3 and 3 ×1016 m-3 using a two photon process in which the energy of one of the photons is adjustable. The excess photon energy above the ionization threshold sets the electron temperature, Te, and thus gives us control of κf. The resultant plasma is a classical plasma with strongly coupled ions, and is therefore described by the Yukawa OCP model with the electrons treated as a screening background. After photoionization, the ions develop spatial correlations to minimize their interaction energy, thus heating the ions. Since the dynamics of a Yukawa OCP depend solely on κ, we expect the heating process to be uniquely determined by κf. We verify this behavior by measuring the ion heating curve and comparing it to molecular dynamics simulations. We also report on how this behavior can be used to accurately measure n given a measured equilibration curve at a known Te. This work was supported by the United States National Science Foundation and the Department of Energy (PHY-0714603), the Air Force Office of Scientific Research (FA9550- 12-1-0267), and the Department of Defense (DoD) through the NDSEG Program.

  12. Thermal plasma processing

    SciTech Connect

    Boulos, M.I. . Dept. of Chemical Engineering)

    1991-12-01

    This paper is a review of the fundamental aspects involved in material processing using thermal plasma technology. The description of plasma-generating devices covers dc plasma torches, dc transferred arcs, radio-frequency (RF) inductively coupled plasma torches, and hybrid combinations of them. Emphasis is given to the identification of the basic energy-coupling mechanism in each case and the principal characteristics of the flow and temperature fields in the plasma. Materials-processing techniques using thermal plasmas are grouped in two broad categories, depending on the role played by the plasma in the process. Only typical examples are given in this review of each type of processes. The simplest and most widely used processes such as spheroidization, melting, deposition, and spray-coating make use of the plasma only as a high-temperature energy source. Thermal plasma technology is also used in applications involving chemical synthesis in which the plasma acts as a source of chemically active species.

  13. Synthesis of Amorphous Alloy Nanoparticles by Thermal Plasma Jet in a Quenching Tube

    NASA Astrophysics Data System (ADS)

    Choi, Sooseok; Park, Dong-Wha

    2015-09-01

    Recently, amorphous alloy nanoparticles have received a great attention in various applications such as catalysts, compact and highly efficient transformers, electrode material for Li-ion batteries, etc. Several methods such as microwave heating, laser ablation, and sonification have been studied to synthesize amorphous metal nanoparticles. In the present work, a high velocity thermal plasma jet generated by an arc plasma torch was used to produce iron alloy nanoparticles from an amorphous raw material which was a spherical shaped powder with the mean size of 25 μm. In order to synthesize amorphous alloy nanoparticles, a quenching tube where cooling gas was injected in different axial positions. Alloy nanoparticles were produced in a relatively high input power of higher than 10 kW in a fixed powder feeding at 300 mg/min. The crystallinity of synthesized nanoparticles was decreased with increasing the quenching gas flow rate. The amorphous alloy nanoparticles were found when the quenching gas injection position was 200 mm away from the exit of the plasma torch with the highest quenching gas flow rate of 20 L/min. In the numerical analysis, the highest quenching rate was also expected at the same condition.

  14. Characterization of the plasma current quench during disruptions in the National Spherical Torus Experiment

    SciTech Connect

    Gerhardt, S.P., Menard, J.E., and the NSTX Research Team

    2008-12-17

    A detailed analysis of the plasma current quench in the National Spherical Torus Experiment [M.Ono, et al Nuclear Fusion 40, 557 (2000)] is presented. The fastest current quenches are fit better by a linear waveform than an exponential one. Area-normalized current quench times down to .4 msec/m2 have been observed, compared to the minimum of 1.7 msec/m2 recommendation based on conventional aspect ratio tokamaks; as noted in previous ITPA studies, the difference can be explained by the reduced self-inductance at low aspect ratio and high-elongation. The maximum instantaneous dIp/dt is often many times larger than the mean quench rate, and the plasma current before the disruption is often substantially less than the flat-top value. The poloidal field time-derivative during the disruption, which is directly responsible for driving eddy currents, has been recorded at various locations around the vessel. The Ip quench rate, plasma motion, and magnetic geometry all play important roles in determining the rate of poloidal field change.

  15. Numerical simulation of the plasma current quench following a disruptive energy loss

    SciTech Connect

    Strickler, D.J.; Peng, Y.K.M.; Holmes, J.A.; Miller, J.B.; Rothe, K.E.

    1983-11-01

    The plasma electromagnetic interaction with poloidal field coils and nearby passive conductor loops during the current quench following a disruptive loss of plasma energy is simulated. By solving a differential/algebraic system consisting of a set of circuit equations (including the plasma circuit) coupled to a plasma energy balance equation and an equilibrium condition, the electromagnetic consequences of an abrupt thermal quench are observed. Limiters on the small and large major radium sides of the plasma are assumed to define the plasma cross section. The presence of good conductors near the plasma and a small initial distance (i.e., 5 to 10% of the plasma minor radius) between the plasma edge and an inboard limiter are shown to lead to long current decay times. For a plasma with an initial major radius R/sub o/ = 4.3 m, aspect ratio A = 3.6, and current I/sub P/ = 4.0 MA, introducing nearby passive conductors lengthens the current decay from milliseconds to hundreds of milliseconds.

  16. Plasma Processing Of Hydrocarbon

    SciTech Connect

    Grandy, Jon D; Peter C. Kong; Brent A. Detering; Larry D. Zuck

    2007-05-01

    The Idaho National Laboratory (INL) developed several patented plasma technologies for hydrocarbon processing. The INL patents include nonthermal and thermal plasma technologies for direct natural gas to liquid conversion, upgrading low value heavy oil to synthetic light crude, and to convert refinery bottom heavy streams directly to transportation fuel products. Proof of concepts has been demonstrated with bench scale plasma processes and systems to convert heavy and light hydrocarbons to higher market value products. This paper provides an overview of three selected INL patented plasma technologies for hydrocarbon conversion or upgrade.

  17. Is the electron avalanche process in a martian dust devil self-quenching?

    NASA Astrophysics Data System (ADS)

    Farrell, W. M.; McLain, J. L.; Collier, M. R.; Keller, J. W.; Jackson, T. J.; Delory, G. T.

    2015-07-01

    Viking era laboratory experiments show that mixing tribocharged grains in a low pressure CO2 gas can form a discharge that glows, indicating the presence of an excited electron population that persists over many seconds. Based on these early experiments, it has been predicted that martian dust devils and storms may also contain a plasma and new plasma chemical species as a result of dust grain tribo-charging. However, recent results from modeling suggest a contrasting result: that a sustained electron discharge may not be easily established since the increase in gas conductivity would act to short-out the local E-fields and quickly dissipate the charged grains driving the process. In essence, the system was thought to be self-quenching (i.e., turn itself off). In this work, we attempt to reconcile the difference between observation and model via new laboratory measurements. We conclude that in a Mars-like low pressure CO2 atmosphere and expected E-fields, the electron current remains (for the most part) below the expected driving tribo-electric dust currents (∼10 μA/m2), thereby making quenching unlikely.

  18. Is the Electron Avalanche Process in a Martian Dust Devil Self-Quenching?

    NASA Technical Reports Server (NTRS)

    Farrell, William M.; McLain, Jason L.; Collier, M. R.; Keller, J. W.; Jackson, T. J.; Delory, G. T.

    2015-01-01

    Viking era laboratory experiments show that mixing tribocharged grains in a low pressure CO2 gas can form a discharge that glows, indicating the presence of an excited electron population that persists over many seconds. Based on these early experiments, it has been predicted that martian dust devils and storms may also contain a plasma and new plasma chemical species as a result of dust grain tribo-charging. However, recent results from modeling suggest a contrasting result: that a sustained electron discharge may not be easily established since the increase in gas conductivity would act to short-out the local E-fields and quickly dissipate the charged grains driving the process. In essence, the system was thought to be self-quenching (i.e., turn itself off). In this work, we attempt to reconcile the difference between observation and model via new laboratory measurements. We conclude that in a Mars-like low pressure CO2 atmosphere and expected E-fields, the electron current remains (for the most part) below the expected driving tribo-electric dust currents (approx. 10 microA/m(exp. 2)), thereby making quenching unlikely.

  19. Quenching of surface-exciton emission from ZnO nanocombs by plasma immersion ion implantation

    SciTech Connect

    Yang, Y.; Tay, B. K.; Sun, X. W.; Sze, J. Y.; Han, Z. J.; Wang, J. X.; Zhang, X. H.; Li, Y. B.; Zhang, S.

    2007-08-13

    Surface modification of ZnO nanocombs was performed through a Ti plasma immersion ion implantation (PIII) with low bias voltages ranging from 0 to 5 kV to quench surface-originated exciton emission. The ion energy dependent surface modification on ZnO was investigated using transmission electron microscopy and temperature-dependent photoluminescence (PL). The surface exciton (SX) was clearly identified for the as-grown sample at 4.5 K, and complete quenching was observed for sample treated with 5 kV PIII due to surface state passivation. The SX related surface states were located within 5 nm in depth from the surface corresponding to the implantation depth of 5 kV PIII. Room-temperature PL enhancement of these surface-modified ZnO nanocombs was observed and discussed. The results show that PIII can become a viable technique for nanostructure surface passivation.

  20. Half-Collision Dynamics of Excited Metal Atom Quenching Processes

    NASA Astrophysics Data System (ADS)

    Wallace, Ingvar Axel, II

    Half-collision studies of the quenching of excited states of Zn by Xe and Cd by H_2, CH_4 and i-C_4H _{10} have been undertaken and have provided information concerning the role of alignment of the excited metal atom p-orbital as well as other dynamical information and details about the potential energy surfaces (curves) involved in the quenching process. Van der Waals complexes of a single metal atom with a rare gas atom or quencher molecule are prepared using a supersonic expansion of the metal vapor, carrier gas and quencher gas. To provide a more detailed understanding of van der Waals bonding involving closed shell metal atoms, spectroscopic investigations of the MgcdotNe, Zncdot Ar and ZncdotKr C ^1Pi_1 and X^1 Sigma_0^+ states as well as the ZncdotXe D^1Sigma _0^+ and X^1Sigma _0^+ states via laser induced fluorescence have also been performed. No fluorescence is observed from the Zn cdotXe C^1Pi_1 state which predissociates to Zn(4s4p^3 P_{rm J}) + Xe, permitting the C state to be characterized via a Zn(4s4p^3P_2) "action spectrum." Modeling of the deeply bound C state and the shallow D state using Morse potentials suggests that the long range tail of the C state curve crosses the inner wall of the D state curve. For the CdcdotCH _4 and CdcdotC _4H_{10} complexes, fluorescence is not observed from either the C or D states. However, Cd(5s5p^3P _{rm J}) action spectra are obtained for C and D state excitation. A Cd(5s5p ^3P_0) action spectrum is observed as a result of CdcdotCH _4 A and B state excitation. Rotational structure is observed in the vibrational bands and has permitted characterization of the Cdcdot CH_4 X and A states within a pseudodiatomic approximation and provided evidence for hindered rotation of the methane molecule. When CdcdotH_2 or CdcdotD_2 is excited to the red of the Cd(5s5p^1 P_1 >=ts 5s5s^1S_0) atomic transition, fluorescence is again absent while Cd(5s5p ^3P_{rm J}) action spectra are observed. The observation in the spectra of

  1. Efficiency droop in indium gallium nitride light emitters: An introduction to photon quenching processes

    NASA Astrophysics Data System (ADS)

    Sarkissian, Raymond

    This thesis contains work from two separate projects, a study of the efficiency of light emitting diodes, and a tapered-fiber approach to photonic crystal integrated photonics. The first part of this thesis describes an experimental investigation of the quantum efficiency of InGaN-based light emitters. Blue and Green LEDs that utilize InGaN quantum wells for their active medium suffer from a reduction in efficiency with increasing bias. This phenomenon is called efficiency droop. In this thesis experimental evidence for significant quenching of photon population in InGaN is presented and its relevance to the efficiency droop problem in InGaN-based light emitting structures is discussed. An equilibrium rate equation model is set up to demonstrate that radiative efficiency for this loss mechanism not only has a similar dependence on carrier density as Auger recombination process, but it also possesses the right order of magnitude making it difficult to distinguish between the two and possibly leading to errors in interpretation. The impact of photon quenching processes on device performance is emphasized by demonstrating loss of efficiency for spectral regions where there is experimental evidence for photon quenching. We have observed this phenomenon for both c-plane and m-plane light emitting structures. Both structures exhibit droop-like behavior for spectral regions where there is evidence for photon quenching. We have also observed and characterized the dynamical Stark effect for an m-plane light emitter considered in this manuscript. Our results revealed localization centers with a corresponding band-edge energy of 388nm and an excitonic binding energy of 17.81mev. Furthermore, fabrication of a photonic crystal waveguide fiber taper coupler is demonstrated with a peak coupling efficiency of 97 %. All four ports of the device are accessible providing an opportunity for investigation of simultaneous interaction of different light sources inside the photonic

  2. Stationary holographic plasma quenches and numerical methods for non-killing horizons.

    PubMed

    Figueras, Pau; Wiseman, Toby

    2013-04-26

    We explore use of the harmonic Einstein equations to numerically find stationary black holes where the problem is posed on an ingoing slice that extends into the interior of the black hole. Requiring no boundary conditions at the horizon beyond smoothness of the metric, this method may be applied for horizons that are not Killing. As a nontrivial illustration we find black holes which, via AdS-CFT, describe a time-independent CFT plasma flowing through a static spacetime which asymptotes to Minkowski in the flow's past and future, with a varying spatial geometry in between. These are the first nonperturbative examples of stationary black holes which do not have Killing horizons. When the CFT spacetime slowly varies, the CFT stress tensor derived from gravity is well described by viscous hydrodynamics. For fast variation it is not, and the solutions are stationary analogs of dynamical quenches, with the plasma being suddenly driven out of equilibrium. We find evidence these flows become unstable for sufficiently strong quenches, and speculate the instability may be turbulent.

  3. Demonstrating universal scaling for dynamics of Yukawa one-component plasmas after an interaction quench.

    PubMed

    Langin, T K; Strickler, T; Maksimovic, N; McQuillen, P; Pohl, T; Vrinceanu, D; Killian, T C

    2016-02-01

    The Yukawa one-component plasma (OCP) model is a paradigm for describing plasmas that contain one component of interest and one or more other components that can be treated as a neutralizing, screening background. In appropriately scaled units, interactions are characterized entirely by a screening parameter, κ. As a result, systems of similar κ show the same dynamics, regardless of the underlying parameters (e.g., density and temperature). We demonstrate this behavior using ultracold neutral plasmas (UNPs) created by photoionizing a cold (T≤10 mK) gas. The ions in UNP systems are well described by the Yukawa model, with the electrons providing the screening. Creation of the plasma through photoionization can be thought of as a rapid quench of the interaction potential from κ=∞ to a final κ value set by the electron density and temperature. We demonstrate experimentally that the postquench dynamics are universal in κ over a factor of 30 in density and an order of magnitude in temperature. Results are compared with molecular-dynamics simulations. We also demonstrate that features of the postquench kinetic energy evolution, such as disorder-induced heating and kinetic-energy oscillations, can be used to determine the plasma density and the electron temperature. PMID:26986426

  4. Perturbative and nonperturbative aspects of jet quenching in near-critical quark-gluon plasmas

    NASA Astrophysics Data System (ADS)

    Xu, Jiechen

    In this thesis, we construct two QCD based energy loss models to perform quantitative analysis of jet quenching observables in ultra-relativistic nucleus-nucleus collisions at RHIC and the LHC. We first build up a perturbative QCD based CUJET2.0 jet flavor tomography model that couples the dynamical running coupling DGLV opacity series to bulk data constrained relativistic viscous hydrodynamic backgrounds. It solves the strong heavy quark energy loss puzzle at RHIC and explains the surprising transparency of the quark-gluon plasma (QGP) at the LHC. The observed azimuthal anisotropy of hard leading hadrons requires a path dependent jet-medium coupling in CUJET2.0 that implies physics of nonperturbative origin. To explore the nonperturbative chromo-electric and chromo-magnetic structure of the strongly-coupled QGP through jet probes, we build up a new CUJET3.0 framework that includes in CUJET2.0 both Polyakov loop suppressed semi-QGP chromo-electric charges and emergent chromo-magnetic monopoles in the critical transition regime. CUJET3.0 quantitatively describes the anisotropic hadron suppression at RHIC and the LHC. More significantly, it provides a robust connection between the long wavelength ``perfect fluidity'' of the QGP and the short distance jet transport in the QGP. This framework paves the way for ``measuring'' both perturbative and nonperturbative properties of the QGP, and more importantly for probing color confinement through jet quenching.

  5. Synthesis of the monoclinic yttria by thermal plasma processing

    SciTech Connect

    Vogt, G.J.

    1987-01-01

    Submicron powders of monoclinic yttria were prepared by thermal plasma processing of commercial yttria powder. The starting yttria powder was vaporized in the hot tail flame of a thermal argon plasma and the resulting vapor was quenched with hydrogen gas to form yttria particles with a 21-nm mean diameter. The synthesis of yttria by oxidizing yttrium carbide in the plasma was also examined. The plasma powders were characterized by powder x-ray diffraction, transmission electron microscopy, and differential thermal analysis. 13 refs., 4 figs., 4 tabs.

  6. Processes in relativistic plasmas

    SciTech Connect

    Gould, R.J.

    1982-03-15

    The problem of the establishment and maintenance of a Boltzmann distribution in particle kinetic energies is discussed for a plasma with THETA = kT/sub e//mc/sup 2/>>1, where m is the electron mass. It is shown that thermalization of the electron gas by binary collisions (Moller scattering) is not sufficiently effective to maintain the equilibrium distribution when other processes are considered which act to perturb the equilibrium. In particular, for THETA>3.5 the relaxation time tau/sub M/ by Moller scattering is larger than the time tau/sub B/ for losses by bremsstrahlung in electron-electron and electron-ion collisions is also evaluated. It is shown that this process dominates Moller scattering when THETA> or approx. =34.

  7. Modelling of the carburizing and quenching process applied to caterpillar track bushings

    NASA Astrophysics Data System (ADS)

    Ferro, P.; Bonollo, F.

    2014-03-01

    The carburizing-quenching process applied to caterpillar track bushings was studied by means of experimental and numerical analyses. The numerical model was developed on the basis of the real cycle. The purpose of this work is to predict the carbon profiles, microstructural phase changes, hardness and residual stress that occur during quenching using finite element techniques. Good agreement was obtained between the experimental and numerical results in terms of carbon diffusion and hardness profiles. The Sysweld® numerical code was used to perform the simulations.

  8. Thermal plasma processing of materials

    SciTech Connect

    Pfender, E.; Heberlein, J.

    1992-02-01

    Emphasis has been on plasma synthesis of fine powders, plasma Chemical Vapor Deposition (CVD), on related diagnostics, and on modeling work. Since plasma synthesis as well as plasma CVD make frequent use of plasma jets, the beginning has been devoted of plasma jets and behavior of particulates injected into such plasma jets. Although most of the construction of the Triple-Torch Plasma Reactor (TTPR) has already been done, modifications have been made in particular modifications required for plasma CVD of diamond. A new reactor designed for Counter-Flow Liquid Injection Plasma Synthesis (CFLIPS) proved to be an excellent tool for synthesis of fine powders as well as for plasma CVD. An attempt was made to model flow and temperature fields in this reactor. Substantial efforts were made to single out those parameters which govern particle size, size distribution, and powder quality in our plasma synthesis experiments. This knowledge is crucial for controlling the process and for meaningful diagnostics and modeling work. Plasma CVD of diamond films using both reactors has been very successful and we have been approached by a number of companies interested in using this technology for coating of tools.

  9. The Effect of Hardenability Variation on Phase Transformation of Spiral Bevel Gear in Quenching Process

    NASA Astrophysics Data System (ADS)

    Zhang, Yingtao; Shi, Wankai; Yang, Lin; Gu, Zhifei; Li, Zhichao

    2016-07-01

    The hardenability of gear steel is dependent on the composition of alloying elements and is one of important criteria to assess process of phase transformation. The variation of hardenability has to be considered in control of the microstructures and distortion during gear quenching. In this paper, the quantitative effect of hardenability has been investigated on phase transformations of spiral bevel gears in die quenching. The hardenability deviation of 22CrMoH steel was assessed by using Jominy test. The dilatometry experiments were conducted to build phase transformation kinetic models for steels with low and high hardenability, respectively. The complete die quenching process of spiral bevel gear was modeled to reveal the significant difference on microstructures and temperature history with variation of hardenability. The final microstructures of the gear are martensite in surface layer after quenching process. There are bainite inside the gear tooth and the mixture of bainite and ferrite inside gear for the gear with low hardenability. The microstructure is bainite inside the gear with high hardenability.

  10. Transport processes in space plasmas

    SciTech Connect

    Birn, J.; Elphic, R.C.; Feldman, W.C.

    1997-08-01

    This is the final report of a three-year, Laboratory Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The project represents a comprehensive research effort to study plasma and field transport processes relevant for solar-terrestrial interaction, involving the solar wind and imbedded magnetic field and plasma structures, the bow shock of the Earth`s magnetosphere and associated waves, the Earth`s magnetopause with imbedded flux rope structures and their connection with the Earth, plasma flow in the Earth`s magnetotail, and ionospheric beam/wave interactions. The focus of the work was on the interaction between plasma and magnetic and electric fields in the regions where different plasma populations exist adjacent to or superposed on each other. These are the regions of particularly dynamic plasma behavior, important for plasma and energy transport and rapid energy releases. The research addressed questions about how this interaction takes place, what waves, instabilities, and particle/field interactions are involved, how the penetration of plasma and energy through characteristic boundaries takes place, and how the characteristic properties of the plasmas and fields of the different populations influence each other on different spatial and temporal scales. These topics were investigated through combining efforts in the analysis of plasma and field data obtained through space missions with theory and computer simulations of the plasma behavior.

  11. Properties of Nb3Al Wires Processed by Double Rapid Heating and Quenching

    NASA Astrophysics Data System (ADS)

    Tsuchiya, K.; Kikuchi, A.; Takeuchi, T.; Banno, N.; Iijima, Y.; Nimori, S.; Takigawa, H.; Yoshida, M.; Tomita, K.; Kato, S.; Takao, T.; Nakamoto, T.; Nakagawa, K.

    We have been developing Nb3Al wires processed by rapid heating and quenching for a number of years as promising candidates for use in future high-field accelerator magnets. These wires have better strain and stress tolerances than Nb3Sn wires do, but to meet the demands of future accelerator magnet designs, it is necessary to further improve their performance. In particular,it is necessary to increase their non-copper critical current density in 12-20T fields. To pursue this goal, we introduced double rapid heating and quenching (DRHQ) treatment into the fabrication process for Nb3Al wires, and studied the mechanical and superconducting properties of the resulting DRHQ-processed wires.

  12. Thermodynamics and jet-quenching in the quark-gluon plasma from an AdS/QCD model

    NASA Astrophysics Data System (ADS)

    Lilleskov, Elias; Bartz, Sean

    2015-10-01

    The Anti-de Sitter Space/Conformal Field Theory Correspondence (AdS/CFT) has been used to study both hadronic dynamics and the thermodynamics and jet quenching behavior of the quark-gluon plasma created in heavy ion collisions. We attempt to connect the two regimes by adapting an AdS/QCD model previously used to study meson spectra to apply to the quark-gluon plasma. The model includes three fields: a dilaton to introduce confinement, and chiral and glueball condensates to reflect the zero-temperature dynamics. We dynamically solve the Einstein field equations to numerically determine the metric, which asymptotically describes an anti-de Sitter-Schwarzschild black hole solution. We then numerically calculate the temperature as a function of the black hole horizon location. Next, we determine the behavior of the entropy density, the speed of sound, and the jet quenching parameter as functions of the temperature. These quantities approach the behavior of a conformal plasma in the high temperature limit. The minimum of the temperature-horizon plot is interpreted as the plasma's deconfinement temperature, found to be 104 MeV.

  13. Quenching investigation on new erbium doped fibers using MCVD nanoparticle doping process

    NASA Astrophysics Data System (ADS)

    Boivin, David; Föhn, Thomas; Burov, Ekaterina; Pastouret, Alain; Gonnet, Cédric; Cavani, Olivier; Collet, Christine; Lempereur, Simon

    2010-02-01

    Ever demanding network implementations brought new requirements to be addressed to offer cost effective and power efficient solutions with smaller footprints. This general trend together with the constant need to improve L-band optical amplification efficiency account for the renewed interest on highly doped Erbium fibers. Erbium doped fiber amplifiers (EDFAs) performance degradation with Er3+ concentration increase has extensively been studied1 and is attributed to additional losses due to energy transfers between neighbouring ions. Experimental observations have been interpreted by the homogeneous up-conversion (HUC) and pair-induced quenching (PIQ) models, which account for pump power penalty and unsaturable absorption respectively. For a given Er3+ concentration, studies have also showed that both fiber manufacturing process and core matrix composition have a strong impact on quenching parameters. In 2009, we introduced a new doping concept involving Al2O3Er nanoparticles (NP) in a MCVD-compatible process showing improved performances in terms of erbium homogeneity along the fiber length for standard doping levels.2 In this paper, we address our most recent work on concentration quenching encountered in both standard and NP Erbium doped fibers.

  14. Plasma Processing of Advanced Materials

    SciTech Connect

    Heberlein, Joachim, V.R.; Pfender, Emil; Kortshagen, Uwe

    2005-02-28

    Plasma Processing of Advanced Materials The project had the overall objective of improving our understanding of the influences of process parameters on the properties of advanced superhard materials. The focus was on high rate deposition processes using thermal plasmas and atmospheric pressure glow discharges, and the emphasis on superhard materials was chosen because of the potential impact of such materials on industrial energy use and on the environment. In addition, the development of suitable diagnostic techniques was pursued. The project was divided into four tasks: (1) Deposition of superhard boron containing films using a supersonic plasma jet reactor (SPJR), and the characterization of the deposition process. (2) Deposition of superhard nanocomposite films in the silicon-nitrogen-carbon system using the triple torch plasma reactor (TTPR), and the characterization of the deposition process. (3) Deposition of films consisting of carbon nanotubes using an atmospheric pressure glow discharge reactor. (4) Adapting the Thomson scattering method for characterization of atmospheric pressure non-uniform plasmas with steep spatial gradients and temporal fluctuations. This report summarizes the results.

  15. Surface-directed phase separation via a two-step quench process in binary polymer mixture films with asymmetry compositions.

    PubMed

    Yan, Li-Tang; Li, Jialin; Zhang, Fengbo; Xie, Xu-Ming

    2008-07-24

    Surface-directed phase separation via a two-step quench process in asymmetry polymer mixtures is numerically investigated by coupling the Flory-Huggins-de Gennes equation with the Cahn-Hilliard-Cook equation. Two distinct situations, i.e., the minority component is preferred by the surface and the majority component is preferred by the surface, are discussed, respectively. The morphology and evolution dynamics of the phase structure, especially the secondary domain structure, are analyzed. The wetting layer formation mechanisms during the two-step quench process are examined. The simulated results demonstrate that different secondary domain structures in these two situations can be induced by the second quench with deeper quench depth, which can be used to tailor phase morphology. It is also found that, in the second quench process, the evolution of the wetting layer thickness can cross over to a faster growth when the preferential component is the minority component. In this situation, the formation mechanism of the wetting layer will change and is eventually determined by the second quench depth. However, when the preferential component is the majority component, a deeper second quench depth corresponds to a slower growth of the wetting layer thickness. The chemical potential is calculated to explain the difference regarding the growth dynamics of the wetting layer thickness between these both situations. PMID:18582100

  16. Fluorophore-based sensor for oxygen radicals in processing plasmas

    SciTech Connect

    Choudhury, Faraz A.; Shohet, J. Leon; Sabat, Grzegorz; Sussman, Michael R.; Nishi, Yoshio

    2015-11-15

    A high concentration of radicals is present in many processing plasmas, which affects the processing conditions and the properties of materials exposed to the plasma. Determining the types and concentrations of free radicals present in the plasma is critical in order to determine their effects on the materials being processed. Current methods for detecting free radicals in a plasma require multiple expensive and bulky instruments, complex setups, and often, modifications to the plasma reactor. This work presents a simple technique that detects reactive-oxygen radicals incident on a surface from a plasma. The measurements are made using a fluorophore dye that is commonly used in biological and cellular systems for assay labeling in liquids. Using fluorometric analysis, it was found that the fluorophore reacts with oxygen radicals incident from the plasma, which is indicated by degradation of its fluorescence. As plasma power was increased, the quenching of the fluorescence significantly increased. Both immobilized and nonimmobilized fluorophore dyes were used and the results indicate that both states function effectively under vacuum conditions. The reaction mechanism is very similar to that of the liquid dye.

  17. Application of Quenching and Partitioning (Q&P) Processing to Press Hardening Steel

    NASA Astrophysics Data System (ADS)

    Seo, Eun Jung; Cho, Lawrence; De Cooman, Bruno Charles

    2014-08-01

    Press hardening steel (PHS) has been increasingly used for the manufacture of structural automotive parts in recent years. One of the most critical characteristics of PHS is a low residual ductility related to a martensitic microstructure. The present work proposes the application of quenching and partitioning (Q&P) processing to improve the ductility of PHS. Q&P processing was applied to a Si- and Cr-added Q&P-compatible PHS, leading to a press hardened microstructure consisting of a tempered martensite matrix containing carbide-free bainite and retained austenite. The simultaneous addition of Si and Cr was used to increase the retained austenite fraction in the Q&P-compatible PHS. The Q&P processing of the PHS resulted in a high volume fraction of C-enriched retained austenite, and excellent mechanical properties. After a quench at 543 K (270 °C) and a partition treatment at 673 K (400 °C), the PHS microstructure contained a high volume fraction of retained austenite and a total elongation (TE) of 17 pct was achieved. The yield strength (YS) and the tensile strength were 1098 and 1320 MPa, respectively. The considerable improvement of the ductility of the Q&P-compatible PHS should lead to an improved in-service ductility beneficial to the passive safety of vehicle passengers.

  18. Method & apparatus for monitoring plasma processing operations

    DOEpatents

    Smith, Jr., Michael Lane; Ward, Pamela Denise; Stevenson, Joel O'Don

    2004-10-19

    The invention generally relates to various aspects of a plasma process and, more specifically, to the monitoring of such plasma processes. One aspect relates to a plasma monitoring module that may be adjusted in at least some manner so as to re-evaluate a previously monitored plasma process. For instance, optical emissions data on a plasma process that was previously monitored by the plasma monitoring module may be replayed through the plasma monitoring module after making at least one adjustment in relation to the plasma monitoring module.

  19. Influence of shell-quenching far from stability on the astrophysical r-process

    NASA Astrophysics Data System (ADS)

    Chen, B.; Dobaczewski, J.; Kratz, K.-L.; Langanke, K.; Pfeiffer, B.; Thielemann, F.-K.; Vogel, P.

    1995-02-01

    Comparison of results from r-process calculations within the waiting-point assumption and the r-process component (Nr,solar) of the solar-system composition of heavy elements, permits to test nuclear structure far from stability. Previous investigations, making use of nuclear mass predictions from global macroscopic-microscopic models, showed abundance deficiencies around A ~= 120 and 140, indicating an overly strong N = 82 strength (some models also showed problems around A ~= 180 related to the N = 126 shell). In this paper we calculate masses based on Skyrme interactions locally around N = 82, within the HF+BCS method with the SIII interaction and the HFB theory with SkP interaction. The shell-quenching obtained in the latter approach results in a considerable improvement of the global Nr,solar fit, indicating a solution to a puzzle existing in r-process nucleosynthesis.

  20. Cold plasma processing technology makes advances

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cold plasma (AKA nonthermal plasma, cool plasma, gas plasma, etc.) is a rapidly maturing antimicrobial process being developed for applications in the food industry. A wide array of devices can be used to create cold plasma, but the defining characteristic is that they operate at or near room temper...

  1. Fast quench reactor method

    SciTech Connect

    Detering, Brent A.; Donaldson, Alan D.; Fincke, James R.; Kong, Peter C.; Berry, Ray A.

    1999-01-01

    A fast quench reaction includes a reactor chamber having a high temperature heating means such as a plasma torch at its inlet and a means of rapidly expanding a reactant stream, such as a restrictive convergent-divergent nozzle at its outlet end. Metal halide reactants are injected into the reactor chamber. Reducing gas is added at different stages in the process to form a desired end product and prevent back reactions. The resulting heated gaseous stream is then rapidly cooled by expansion of the gaseous stream.

  2. Fast quench reactor method

    DOEpatents

    Detering, B.A.; Donaldson, A.D.; Fincke, J.R.; Kong, P.C.; Berry, R.A.

    1999-08-10

    A fast quench reaction includes a reactor chamber having a high temperature heating means such as a plasma torch at its inlet and a means of rapidly expanding a reactant stream, such as a restrictive convergent-divergent nozzle at its outlet end. Metal halide reactants are injected into the reactor chamber. Reducing gas is added at different stages in the process to form a desired end product and prevent back reactions. The resulting heated gaseous stream is then rapidly cooled by expansion of the gaseous stream. 8 figs.

  3. Plasma hearth process demonstration project

    SciTech Connect

    Geimer, R.M.; Gillins, R.L.

    1995-12-31

    The Plasma Hearth Process (PHP) demonstration project is one of the key technology projects in the US Department of Energy (DOE) Office of Technology Development Mixed Waste Focus Area. The PHP is a high temperature thermal treatment process using a plasma arc torch in a stationary, refractory lined chamber that destroys organics and stabilizes the residuals in a nonleaching, vitrified waste form, greatly improving the disposability of the waste. This paper describes the PHP system and summarizes test results to date, including volume reduction, destruction and removal efficiencies for organic wastes, and emission characteristics. Tests performed so far demonstrate that the PHP adresses DOE mixed waste final waste form requirements and US Environmental Protection Agency Toxicity Characteristic Leaching Procedure requirements.

  4. The plasma hearth process: Process residuals characterization

    SciTech Connect

    Leatherman, G.L.; Geimer, R.; Batdorf, J.; Hassel, G.; Wolfe, P.; Carney, K.P.

    1994-12-31

    The Plasma Hearth Process (PHP) is a high-temperature waste treatment process being developed by Science Applications International Corporation (SAIC) for the Department of Energy (DOE) that destroys hazardous organics while stabilizing radionuclides and hazardous metals in a vitreous slag waste form. The PHP has potential application for the treatment of a wide range of mixed waste types in both the low-level and transuranic (TRU) mixed waste categories. DOE, through the Office of Technology Development`s Mixed Waste Integrated Program (MWIP) is conducting a three phase development project to ready the PHP for implementation in the DOE complex.

  5. Disentangling two non-photochemical quenching processes in Cyclotella meneghiniana by spectrally-resolved picosecond fluorescence at 77K.

    PubMed

    Chukhutsina, Volha U; Büchel, Claudia; van Amerongen, Herbert

    2014-06-01

    Diatoms, which are primary producers in the oceans, can rapidly switch on/off efficient photoprotection to respond to fast light-intensity changes in moving waters. The corresponding thermal dissipation of excess-absorbed-light energy can be observed as non-photochemical quenching (NPQ) of chlorophyll a fluorescence. Fluorescence-induction measurements on Cyclotella meneghiniana diatoms show two NPQ processes: qE1 relaxes rapidly in the dark while qE2 remains present upon switching to darkness and is related to the presence of the xanthophyll-cycle pigment diatoxanthin (Dtx). We performed picosecond fluorescence measurements on cells locked in different (quenching) states, revealing the following sequence of events during full development of NPQ. At first, trimers of light-harvesting complexes (fucoxanthin-chlorophyll a/c proteins), or FCPa, become quenched, while being part of photosystem II (PSII), due to the induced pH gradient across the thylakoid membrane. This is followed by (partial) detachment of FCPa from PSII after which quenching persists. The pH gradient also causes the formation of Dtx which leads to further quenching of isolated PSII cores and some aggregated FCPa. In subsequent darkness, the pH gradient disappears but Dtx remains present and quenching partly pertains. Only in the presence of some light the system completely recovers to the unquenched state.

  6. The effect of plasma shaping on turbulent transport and ExB shear quenching in nonlinear gyrokinetic simulations

    SciTech Connect

    Kinsey, J. E.; Waltz, R. E.; Candy, J.

    2007-10-15

    Nonlinear gyrokinetic simulations with kinetic electron dynamics are used to study the effects of plasma shaping on turbulent transport and ExB shear in toroidal geometry including the presence of kinetic electrons using the GYRO code. Over 120 simulations comprised of systematic scans were performed around several reference cases in the local, electrostatic, collisionless limit. Using a parameterized local equilibrium model for shaped geometry, the GYRO simulations show that elongation {kappa} (and its gradient) stabilizes the energy transport from ion temperature gradient (ITG) and trapped electron mode (TEM) instabilities at fixed midplane minor radius. For scans around a reference set of parameters, the GYRO ion energy diffusivity, in gyro-Bohm units, approximately follows a {kappa}{sup -1} scaling which is qualitatively similar to recent experimental energy confinement scalings. Most of the {kappa} scaling is due to the shear in the elongation rather than the local {kappa} itself. The {kappa} scaling for the electrons is found to vary and can be stronger or weaker than {kappa}{sup -1} depending on the wavenumber where the transport peaks. The {kappa} scaling is weaker when the energy diffusivity peaks at low wavenumbers and is stronger when the peak occurs at high wavenumbers. The simulations also demonstrate a nonlinear upshift in the critical temperature gradient as the elongation increases due to an increase in the residual zonal flow amplitude. Triangularity is found to be slightly destabilizing and its effect is strongest for highly elongated plasmas. Finally, we find less ExB shear is needed to quench the transport at high elongation and low aspect ratio. A new linear ExB shear quench rule, valid for shaped tokamak geometry, is presented.

  7. Solidification Interface Shape and Location During Processing in High Gradient Furnace with Quench

    NASA Technical Reports Server (NTRS)

    Woodbury, Keith A.

    1996-01-01

    High Gradient Furnace with Quench (HGFQ) is being developed to facilitate metals processing experiments aboard the International Space Station. The sample is centered in an annular furnace and is held fixed during processing. The furnace itself is made to translate over the sample. Once in process, heat will flow through the sample from the Heater Zone to the Chill Zone. If operating conditions are correct, the solidification interface will stand in the gradient zone. Objectives of the HGFQ process are to provide a high gradient for the solidification with the solidification interface properly positioned in the gradient zone. At the recent RDR for HGFQ, one of the panelists raised the question about the suitability of HGFQ for potential future PIs. Specifically, it was stated by the design team at RDR that the present HGFQ design would provide a radius of curvature of the solidification interface of at least one sample diameter. The RDR panel argued that this was too small, and that most investigators would need a radius of curvature larger than this. The requirements established by the current PIs are shown. These requirements do not contain any specification about the interface shape. However, these requirements do define the envelope of operational parameters for HGFQ. The objectives of the present investigation are to 1) determine a suitable means of quantifying the interface shape, and 2) investigate the interface shape and how it is affected by processing parameters. The processing parameters to be considered are 1) sample material, 2) sample diameter, and 3) gradient zone length.

  8. The quenching effect of hydrogen on the nitrogen in metastable state in atmospheric-pressure N{sub 2}-H{sub 2} microwave plasma torch

    SciTech Connect

    Li, Shou-Zhe Zhang, Xin; Chen, Chuan-Jie; Zhang, Jialiang; Wang, Yong-Xing; Xia, Guang-Qing

    2014-07-15

    The atmospheric-pressure microwave N{sub 2}-H{sub 2} plasma torch is generated and diagnosed by optical emission spectroscopy. It is found that a large amount of N atoms and NH radicals are generated in the plasma torch and the emission intensity of N{sub 2}{sup +} first negative band is the strongest over the spectra. The mixture of hydrogen in nitrogen plasma torch causes the morphology of the plasma discharge to change with appearance that the afterglow shrinks greatly and the emission intensity of N{sub 2}{sup +} first negative band decreases with more hydrogen mixed into nitrogen plasma. In atmospheric-pressure microwave-induced plasma torch, the hydrogen imposes a great influence on the characteristics of nitrogen plasma through the quenching effect of the hydrogen on the metastable state of N{sub 2}.

  9. INTRODUCTION: Nonequilibrium Processes in Plasmas

    NASA Astrophysics Data System (ADS)

    Petrović, Zoran; Marić, Dragana; Malović, Gordana

    2009-07-01

    This book aims to give a cross section from a wide range of phenomena that, to different degrees, fall under the heading of non-equilibrium phenomenology. The selection is, of course, biased by the interests of the members of the scientific committee and of the FP6 Project 026328 IPB-CNP Reinforcing Experimental Centre for Non-equilibrium Studies with Application in Nano-technologies, Etching of Integrated Circuits and Environmental Research. Some of the papers included here are texts based on selected lectures presented at the Second International Workshop on Non-equilibrium Processes in Plasmas and Environmental Science. However, this volume is not just the proceedings of that conference as it contains a number of papers from authors that did not attend the conference. The goal was to put together a volume that would cover the interests of the project and support further work. It is published in the Institute of Physics journal Journal of Physics: Conference Series to ensure a wide accessibility of the articles. The texts presented here range from in-depth reviews of the current status and past achievements to progress reports of currently developed experimental devices and recently obtained still unpublished results. All papers have been refereed twice, first when speakers were selected based on their reputation and recently published results, and second after the paper was submitted both by the editorial board and individual assigned referees according to the standards of the conference and of the journal. Nevertheless, we still leave the responsibility (and honours) for the contents of the papers to the authors. The papers in this book are review articles that give a summary of the already published work or present the work in progress that will be published in full at a later date (or both). In the introduction to the first volume, in order to show how far reaching, ubiquitous and important non-equilibrium phenomena are, we claimed that ever since the early

  10. Influence of quenching gas injection on the temperature field in pulse-modulated induction thermal plasma for large scale nanopowder synthesis

    NASA Astrophysics Data System (ADS)

    Tanaka, Yasunori; Guo, Weixuan; Kodama, Naoto; Kita, Kentaro; Uesugi, Yoshihiko; Ishijima, Tatsuo; Watanabe, Shu; Nakamura, Keitaro

    2015-09-01

    We have so far developed a unique and original method for a large-scale nanopowder synthesis method using pulse-modulated induction thermal plasmas with time-controlled feedstock feeding (PMITP-TCFF). The PMITP is sustained by the coil current modulated into a rectangular waveform. Such the current modulation produces an extremely high-temperature thermal plasma in on-time, and in off-time relatively low-temperature thermal plasma. In PMITP-TCFF method, feedstock powder is intermittently injected to the PMITP synchronously during only on-time for its efficient and complete evaporation. That evaporated materials are rapidly cooled down to promote nucleation of nanoparticles during off-time. This report deals with a numerical approach on influence of quenching gas injection on the temperature field in the PMITP. The thermofluid model for the PMITP was developed on the assumption of local thermodynamic equilibrium (LTE). This model accounted for the pulse-modulation of the coil current and the quenching gas injection. It was found that the quenching gas injection works to increase the PMITP temperature inside the plasma torch during on-time, and then to decrease it effectively in the reaction chamber. This work is partly supported by JSPS KAKENHI Grant No. 26249034.

  11. Plasma chemistry study of PLAD processes

    NASA Astrophysics Data System (ADS)

    Qin, Shu; Brumfield, Kyle; Liu, Lequn Jennifer; Hu, Yongjun Jeff; McTeer, Allen; Hsu, Wei Hui; Wang, Maoying

    2012-11-01

    Plasma doping (PLAD) shows very different impurity profiles compared to the conventional beam-line-based ion implantations due to its non-mass separation property and plasma environment. There is no simulation for PLAD process so far due to a lack of a dopant profile model. Several factors determine impurity profiles of PLAD process. The most significant factors are: plasma chemistry and deposition/etching characteristics of multi-ion species plasmas. In this paper, we present plasma chemistry and deposition/etching characteristics of PLAD processes versus co-gas dilutions. Four dopant plasmas including B2H6, BF3, AsH3, and PH3, and two non-dopant plasmas including CH4 and GeH4 are studied and demonstrated.

  12. Plasma generating apparatus for large area plasma processing

    DOEpatents

    Tsai, Chin-Chi; Gorbatkin, Steven M.; Berry, Lee A.

    1991-01-01

    A plasma generating apparatus for plasma processing applications is based on a permanent magnet line-cusp plasma confinement chamber coupled to a compact single-coil microwave waveguide launcher. The device creates an electron cyclotron resonance (ECR) plasma in the launcher and a second ECR plasma is created in the line cusps due to a 0.0875 tesla magnetic field in that region. Additional special magnetic field configuring reduces the magnetic field at the substrate to below 0.001 tesla. The resulting plasma source is capable of producing large-area (20-cm diam), highly uniform (.+-.5%) ion beams with current densities above 5 mA/cm.sup.2. The source has been used to etch photoresist on 5-inch diam silicon wafers with good uniformity.

  13. Plasma generating apparatus for large area plasma processing

    DOEpatents

    Tsai, C.C.; Gorbatkin, S.M.; Berry, L.A.

    1991-07-16

    A plasma generating apparatus for plasma processing applications is based on a permanent magnet line-cusp plasma confinement chamber coupled to a compact single-coil microwave waveguide launcher. The device creates an electron cyclotron resonance (ECR) plasma in the launcher and a second ECR plasma is created in the line cusps due to a 0.0875 tesla magnetic field in that region. Additional special magnetic field configuring reduces the magnetic field at the substrate to below 0.001 tesla. The resulting plasma source is capable of producing large-area (20-cm diam), highly uniform (.+-.5%) ion beams with current densities above 5 mA/cm[sup 2]. The source has been used to etch photoresist on 5-inch diam silicon wafers with good uniformity. 3 figures.

  14. INTRODUCTION: Nonequilibrium Processes in Plasmas

    NASA Astrophysics Data System (ADS)

    Petrović, Zoran; Marić, Dragana; Malović, Gordana

    2009-07-01

    This book aims to give a cross section from a wide range of phenomena that, to different degrees, fall under the heading of non-equilibrium phenomenology. The selection is, of course, biased by the interests of the members of the scientific committee and of the FP6 Project 026328 IPB-CNP Reinforcing Experimental Centre for Non-equilibrium Studies with Application in Nano-technologies, Etching of Integrated Circuits and Environmental Research. Some of the papers included here are texts based on selected lectures presented at the Second International Workshop on Non-equilibrium Processes in Plasmas and Environmental Science. However, this volume is not just the proceedings of that conference as it contains a number of papers from authors that did not attend the conference. The goal was to put together a volume that would cover the interests of the project and support further work. It is published in the Institute of Physics journal Journal of Physics: Conference Series to ensure a wide accessibility of the articles. The texts presented here range from in-depth reviews of the current status and past achievements to progress reports of currently developed experimental devices and recently obtained still unpublished results. All papers have been refereed twice, first when speakers were selected based on their reputation and recently published results, and second after the paper was submitted both by the editorial board and individual assigned referees according to the standards of the conference and of the journal. Nevertheless, we still leave the responsibility (and honours) for the contents of the papers to the authors. The papers in this book are review articles that give a summary of the already published work or present the work in progress that will be published in full at a later date (or both). In the introduction to the first volume, in order to show how far reaching, ubiquitous and important non-equilibrium phenomena are, we claimed that ever since the early

  15. Atmospheric Pressure Plasma Process And Applications

    SciTech Connect

    Peter C. Kong; Myrtle

    2006-09-01

    This paper provides a general discussion of atmospheric-pressure plasma generation, processes, and applications. There are two distinct categories of atmospheric-pressure plasmas: thermal and nonthermal. Thermal atmospheric-pressure plasmas include those produced in high intensity arcs, plasma torches, or in high intensity, high frequency discharges. Although nonthermal plasmas are at room temperatures, they are extremely effective in producing activated species, e.g., free radicals and excited state atoms. Thus, both thermal and nonthermal atmosphericpressure plasmas are finding applications in a wide variety of industrial processes, e.g. waste destruction, material recovery, extractive metallurgy, powder synthesis, and energy conversion. A brief discussion of recent plasma technology research and development activities at the Idaho National Laboratory is included.

  16. Organic pollutants abatement and biodecontamination of brewery effluents by a non-thermal quenched plasma at atmospheric pressure.

    PubMed

    Doubla, A; Laminsi, S; Nzali, S; Njoyim, E; Kamsu-Kom, J; Brisset, J-L

    2007-09-01

    A preliminary study was carried out to investigate possible decontamination of the waste waters from a Cameroonian brewery by using a non-thermal atmospheric plasma. Samples of waste waters collected during periods of intense activity of production were first analysed for organoleptic, physical-chemical and organic parameters, and then exposed to a humid air electric discharge at ambient temperature and pressure. The resultant pollution abatement and germicidal effects are both ascribed to strong oxidising effects of OH and NO radicals formed in the plasma. The BOD removal efficiency of the process with brewery industrial wastewaters under BOD concentration of 385 and 1018 mg l(-1) were 74% and 98% respectively. The alkaline wastewaters are rapidly neutralised due to the pH lowering effects of the plasma treatment.

  17. Long-lived plasma and fast quenching of N2(C3Π u ) by electrons in the afterglow of a nanosecond capillary discharge in nitrogen

    NASA Astrophysics Data System (ADS)

    Lepikhin, N. D.; Klochko, A. V.; Popov, N. A.; Starikovskaia, S. M.

    2016-08-01

    Quenching of electronically excited nitrogen state, {{\\text{N}}2}≤ft({{\\text{C}}3}{{\\Pi}u},{{v}\\prime}=0\\right) , in the afterglow of nanosecond capillary discharge in pure nitrogen is studied. It is found experimentally that an additional collisional mechanism appears and dominates at high specific deposited energies leading to the anomalously fast quenching of the {{\\text{N}}2}≤ft({{\\text{C}}3}{{\\Pi}u}\\right) in the afterglow. On the basis of obtained experimental data and of the analysis of possible quenching agents, it is concluded that the anomalously fast deactivation of the {{\\text{N}}2}≤ft({{\\text{C}}3}{{\\Pi}u}\\right) can be explained by quenching by electrons. Long-lived plasma at time scale of hundreds nanoseconds after the end of the pulse is observed. High electron densities, about 1014 cm‑3 at 27 mbar, are sustained by reactions of associative ionization. Kinetic 1D numerical modeling and comparison of calculated results with experimentally measured electric fields in the second high-voltage pulse 250 ns after the initial pulse, and electron density measurements in the afterglow confirm the validity of the suggested mechanism.

  18. Long-lived plasma and fast quenching of N2(C3Π u ) by electrons in the afterglow of a nanosecond capillary discharge in nitrogen

    NASA Astrophysics Data System (ADS)

    Lepikhin, N. D.; Klochko, A. V.; Popov, N. A.; Starikovskaia, S. M.

    2016-08-01

    Quenching of electronically excited nitrogen state, {{\\text{N}}2}≤ft({{\\text{C}}3}{{\\Pi}u},{{v}\\prime}=0\\right) , in the afterglow of nanosecond capillary discharge in pure nitrogen is studied. It is found experimentally that an additional collisional mechanism appears and dominates at high specific deposited energies leading to the anomalously fast quenching of the {{\\text{N}}2}≤ft({{\\text{C}}3}{{\\Pi}u}\\right) in the afterglow. On the basis of obtained experimental data and of the analysis of possible quenching agents, it is concluded that the anomalously fast deactivation of the {{\\text{N}}2}≤ft({{\\text{C}}3}{{\\Pi}u}\\right) can be explained by quenching by electrons. Long-lived plasma at time scale of hundreds nanoseconds after the end of the pulse is observed. High electron densities, about 1014 cm-3 at 27 mbar, are sustained by reactions of associative ionization. Kinetic 1D numerical modeling and comparison of calculated results with experimentally measured electric fields in the second high-voltage pulse 250 ns after the initial pulse, and electron density measurements in the afterglow confirm the validity of the suggested mechanism.

  19. Plasma-assisted microwave processing of materials

    NASA Technical Reports Server (NTRS)

    Barmatz, Martin (Inventor); Ylin, Tzu-yuan (Inventor); Jackson, Henry (Inventor)

    1998-01-01

    A microwave plasma assisted method and system for heating and joining materials. The invention uses a microwave induced plasma to controllably preheat workpiece materials that are poorly microwave absorbing. The plasma preheats the workpiece to a temperature that improves the materials' ability to absorb microwave energy. The plasma is extinguished and microwave energy is able to volumetrically heat the workpiece. Localized heating of good microwave absorbing materials is done by shielding certain parts of the workpiece and igniting the plasma in the areas not shielded. Microwave induced plasma is also used to induce self-propagating high temperature synthesis (SHS) process for the joining of materials. Preferably, a microwave induced plasma preheats the material and then microwave energy ignites the center of the material, thereby causing a high temperature spherical wave front from the center outward.

  20. Theoretical investigations of plasma processes

    NASA Technical Reports Server (NTRS)

    Wilhelm, H. E.; Hong, S. H.

    1976-01-01

    System analyses are presented for electrically sustained, collision dominated plasma centrifuges, in which the plasma rotates under the influence of the Lorentz forces resulting from the interaction of the current density fields with an external magnetic field. It is shown that gas discharge centrifuges are technically feasible in which the plasma rotates at speeds up to 1 million cm/sec. The associated centrifugal forces produce a significant spatial isotope separation, which is somewhat perturbed in the viscous boundary layers at the centrifuge walls. The isotope separation effect is the more pronounced. The induced magnetic fields have negligible influence on the plasma rotation if the Hall coefficient is small. In the technical realization of collision dominated plasma centrifuges, a trade-off has to be made between power density and speeds of rotation. The diffusion of sputtered atoms to system surfaces of ion propulsion systems and the deposition of the atoms are treated theoretically by means of a simple model which permits an analytical solution. The problem leads to an inhomogeneous integral equation.

  1. Survey of atomic processes in edge plasmas

    SciTech Connect

    Janev, R.K.; Post, D.E.; Langer, W.D.; Evans, K.; Heifetz, D.B.; Weisheit, J.C.

    1983-11-01

    A review of the most important reactions of atomic and molecular hydrogen with the fusion edge plasma electrons and ions is presented. An appropriate characterization of the considered collision processes, useful in plasma edge studies (evaluated cross sections, reaction rates, energy gain/loss per collision, etc.) has been performed. While a complete survey of atomic physics of fusion edge plasmas will be given elsewhere shortly, we demonstrate here the relevance of the atomic collision processes for describing the physical state of edge plasmas and understanding the energy balance in cool divertor plasmas. It is found that the excited neutral species play an important role in the low-temperature, high-density plasmas.

  2. Atomic processes in optically thin plasmas

    NASA Astrophysics Data System (ADS)

    Kaastra, Jelle S.

    2015-08-01

    The Universe contains a broad range of plasmas with quite different properties depending on distinct physical processes. In this contribution I will give an overview of recent developments in modeling such plasmas with a focus on X-ray emission and absorption. Despite the fact that such plasmas have been investigated already for decades, and that overall there is a good understanding of the basic processes, there are still areas where improvements have to be made that are important for the analysis of astrophysical plasmas. I will present recent work on the update of atomic parameters in the codes that describe the emission from collisional plasmas, where older approximations are being replaced now by more accurate data. Further I discuss the development of models for photo-ionized plasmas in the context of outflows around supermassive black holes and models for charge transfer that are needed for analyzing the data from the upcoming ASTRO-H satellite.

  3. Characterization of the microstructure obtained by the quenching and partitioning process in a low-carbon steel

    SciTech Connect

    Santofimia, M.J. Zhao, L.; Petrov, R.; Sietsma, J.

    2008-12-15

    The 'quenching and partitioning' process is a new heat treatment for the development of multiphase steels with improved mechanical properties. In this work, a partial austenitization followed by Q and P paths, at which the partitioning step is effectuated at a temperature equal to the quenching temperature, has been applied to a low-carbon steel. The resulting multiphase microstructures have been investigated by optical microscopy using bright field and differential interference contrast, electron backscatter diffraction, X-ray diffraction and magnetic measurements. This group of techniques has led to a complete identification of the microstructural constituents: ferrite present during the partial austenitization, epitaxial ferrite formed during cooling, martensite and retained austenite. The analysis of the results has shown a significant relevance of the epitaxial ferrite in the retention of austenite, whereas the carbon partitioning from martensite to austenite has played a minor role.

  4. Effect of Quenching Process on the Microstructure and Hardness of High-Carbon Martensitic Stainless Steel

    NASA Astrophysics Data System (ADS)

    Zhu, Qin-tian; Li, Jing; Shi, Cheng-bin; Yu, Wen-tao

    2015-11-01

    The microstructure and hardness of high-carbon martensitic stainless steel (HMSS) were investigated using thermal expansion analyzer, Thermo-calc, scanning electron microscope, x-ray diffraction, and Ultra-high temperature confocal microscope. The results indicate that the experimental steel should be austenitized in the temperature range of 1025-1075 °C, which can give a maximum hardness of 62 HRc with the microstructure consisting of martensite, retained austenite, and some undissolved carbides. With increasing austenitizing temperature, the amount of retained austenite increases, while the volume fraction of carbides increases first and then decreases. The starting temperature and finish temperature of martensite formation decrease with increasing cooling rates. Air-quenched samples can obtain less retained austenite, more compact microstructure, and higher hardness, compared with that of oil-quenched samples. For HMSS, the martensitic transformation takes place at some isolated areas with a slow nucleation rate.

  5. A plasma process monitor/control system

    SciTech Connect

    Stevenson, J.O.; Ward, P.P.; Smith, M.L.; Markle, R.J.

    1997-08-01

    Sandia National Laboratories has developed a system to monitor plasma processes for control of industrial applications. The system is designed to act as a fully automated, sand-alone process monitor during printed wiring board and semiconductor production runs. The monitor routinely performs data collection, analysis, process identification, and error detection/correction without the need for human intervention. The monitor can also be used in research mode to allow process engineers to gather additional information about plasma processes. The plasma monitor can perform real-time control of support systems known to influence plasma behavior. The monitor can also signal personnel to modify plasma parameters when the system is operating outside of desired specifications and requires human assistance. A notification protocol can be selected for conditions detected in the plasma process. The Plasma Process Monitor/Control System consists of a computer running software developed by Sandia National Laboratories, a commercially available spectrophotometer equipped with a charge-coupled device camera, an input/output device, and a fiber optic cable.

  6. Surface studies of plasma processed Nb samples

    SciTech Connect

    Tyagi, Puneet V; Doleans, Marc; Hannah, Brian S; Afanador, Ralph; Stewart, Stephen; Mammosser, John; Howell, Matthew P; Saunders, Jeffrey W; Degraff, Brian D; Kim, Sang-Ho

    2015-01-01

    Contaminants present at top surface of superconducting radio frequency (SRF) cavities can act as field emitters and restrict the cavity accelerating gradient. A room temperature in-situ plasma processing technology for SRF cavities aiming to clean hydrocarbons from inner surface of cavities has been recently developed at the Spallation Neutron Source (SNS). Surface studies of the plasma processed Nb samples by Secondary ion mass spectrometry (SIMS) and Scanning Kelvin Probe (SKP) showed that the NeO2 plasma processing is very effective to remove carbonaceous contaminants from top surface and improves the surface work function by 0.5 to 1.0 eV.

  7. Transport processes in magnetically confined plasmas

    SciTech Connect

    Callen, J.D.

    1991-12-01

    Intensified studies of plasma transport in toroidal plasmas over the past three to five years have progressed through increased understanding in some areas and changed perceptions about the most important issues in other areas. Recent developments are reviewed for six selected topics: edge fluctuations and transport; L-H mode transition; core fluctuations; modern plasma turbulence theory; transient transport; and global scaling. Some of the developments that are highlighted include: the role of a strongly sheared poloidal flow in edge plasma turbulence, transport and the L-H transition; change of focus from {kappa}{perpendicular}{rho}s {approximately} 1 to {kappa}{perpendicular}{rho}s {much_lt} 1 fluctuations in tokamak plasmas; modern Direct-Interaction-Approximation plasma turbulence and hybrid fluid/kinetic theoretical models; and transient transport experiments that are raising fundamental questions about our conceptions of local transport processes in tokamaks. 104 refs., 6 figs.

  8. Transport processes in magnetically confined plasmas

    SciTech Connect

    Callen, J.D.

    1991-12-01

    Intensified studies of plasma transport in toroidal plasmas over the past three to five years have progressed through increased understanding in some areas and changed perceptions about the most important issues in other areas. Recent developments are reviewed for six selected topics: edge fluctuations and transport; L-H mode transition; core fluctuations; modern plasma turbulence theory; transient transport; and global scaling. Some of the developments that are highlighted include: the role of a strongly sheared poloidal flow in edge plasma turbulence, transport and the L-H transition; change of focus from {kappa}{perpendicular}{rho}s {approximately} 1 to {kappa}{perpendicular}{rho}s {much lt} 1 fluctuations in tokamak plasmas; modern Direct-Interaction-Approximation plasma turbulence and hybrid fluid/kinetic theoretical models; and transient transport experiments that are raising fundamental questions about our conceptions of local transport processes in tokamaks. 104 refs., 6 figs.

  9. Plasma acceleration processes in an ablative pulsed plasma thruster

    SciTech Connect

    Koizumi, Hiroyuki; Noji, Ryosuke; Komurasaki, Kimiya; Arakawa, Yoshihiro

    2007-03-15

    Plasma acceleration processes in an ablative pulsed plasma thruster (APPT) were investigated. APPTs are space propulsion options suitable for microspacecraft, and have recently attracted much attention because of their low electric power requirements and simple, compact propellant system. The plasma acceleration mechanism, however, has not been well understood. In the present work, emission spectroscopy, high speed photography, and magnetic field measurements are conducted inside the electrode channel of an APPT with rectangular geometry. The successive images of neutral particles and ions give us a comprehensive understanding of their behavior under electromagnetic acceleration. The magnetic field profile clarifies the location where the electromagnetic force takes effect. As a result, it is shown that high density, ablated neutral gas stays near the propellant surface, and only a fraction of the neutrals is converted into plasma and electromagnetically accelerated, leaving the residual neutrals behind.

  10. Characterizing Water Quenching Systems with a Quench Probe

    NASA Astrophysics Data System (ADS)

    Ferguson, B. Lynn; Li, Zhichao; Freborg, Andrew M.

    2014-12-01

    Quench probes have been used effectively to characterize the quality of quenchants for many years. For this purpose, a variety of commercial probes, as well as the necessary data acquisition system for determining the time-temperature data for a set of standardized test conditions, are available for purchase. The type of information obtained from such probes provides a good basis for comparing media, characterizing general cooling capabilities, and checking media condition over time. However, these data do not adequately characterize the actual production quenching process in terms of heat transfer behavior in many cases, especially when high temperature gradients are present. Faced with the need to characterize water quenching practices, including conventional and intensive practices, a quench probe was developed. This paper describes that probe, the data collection system, the data gathered for both intensive quenching and conventional water quenching, and the heat transfer coefficients determined for these processes. Process sensitivities are investigated and highlight some intricacies of quenching.

  11. Saturn Plasma Sources and Associated Transport Processes

    NASA Astrophysics Data System (ADS)

    Blanc, M.; Andrews, D. J.; Coates, A. J.; Hamilton, D. C.; Jackman, C. M.; Jia, X.; Kotova, A.; Morooka, M.; Smith, H. T.; Westlake, J. H.

    2015-10-01

    This article reviews the different sources of plasma for Saturn's magnetosphere, as they are known essentially from the scientific results of the Cassini-Huygens mission to Saturn and Titan. At low and medium energies, the main plasma source is the H2O cloud produced by the "geyser" activity of the small satellite Enceladus. Impact ionization of this cloud occurs to produce on the order of 100 kg/s of fresh plasma, a source which dominates all the other ones: Titan (which produces much less plasma than anticipated before the Cassini mission), the rings, the solar wind (a poorly known source due to the lack of quantitative knowledge of the degree of coupling between the solar wind and Saturn's magnetosphere), and the ionosphere. At higher energies, energetic particles are produced by energy diffusion and acceleration of lower energy plasma produced by the interchange instabilities induced by the rapid rotation of Saturn, and possibly, for the highest energy range, by contributions from the CRAND process acting inside Saturn's magnetosphere. Discussion of the transport and acceleration processes acting on these plasma sources shows the importance of rotation-induced radial transport and energization of the plasma, and also shows how much the unexpected planetary modulation of essentially all plasma parameters of Saturn's magnetosphere remains an unexplained mystery.

  12. Fundamental Processes in Plasmas. Final report

    SciTech Connect

    O'Neil, Thomas M.; Driscoll, C. Fred

    2009-11-30

    This research focuses on fundamental processes in plasmas, and emphasizes problems for which precise experimental tests of theory can be obtained. Experiments are performed on non-neutral plasmas, utilizing three electron traps and one ion trap with a broad range of operating regimes and diagnostics. Theory is focused on fundamental plasma and fluid processes underlying collisional transport and fluid turbulence, using both analytic techniques and medium-scale numerical simulations. The simplicity of these systems allows a depth of understanding and a precision of comparison between theory and experiment which is rarely possible for neutral plasmas in complex geometry. The recent work has focused on three areas in basic plasma physics. First, experiments and theory have probed fundamental characteristics of plasma waves: from the low-amplitude thermal regime, to inviscid damping and fluid echoes, to cold fluid waves in cryogenic ion plasmas. Second, the wide-ranging effects of dissipative separatrices have been studied experimentally and theoretically, finding novel wave damping and coupling effects and important plasma transport effects. Finally, correlated systems have been investigated experimentally and theoretically: UCSD experients have now measured the Salpeter correlation enhancement, and theory work has characterized the 'guiding center atoms of antihydrogen created at CERN.

  13. Laser Diagnostics for Plasma Processes

    NASA Astrophysics Data System (ADS)

    Filimonov, Serguei Victor

    The time transients of vibrational/rotational excitation up to v = 7 vibrational level of the ground electronic state of nitrogen were measured in a positive column during the 1-10 mus pulsed electric discharges, and in the afterglow. Current densities were up to 25 A/cm^2, and pressures up to 6 Torr. It is shown that initially energy is being transferred, primarily into vibrational levels above v = 1, resulting in a highly non Boltzmann distribution. The redistribution between vibrational levels takes place within 100 mus after the discharge pulse. Beyond 100 mus the vibrational populations resemble closely Boltzmann distribution. Significant rotational heating was observed in the afterglow and is attributed to energy transfer from vibration to rotation via collisions with electrons. The rotational temperature was as high as 3500 K and reached maximum values between 80 and 100 mus after the discharge pulse. Standard, Coherent Anti-Stokes Raman Spectroscopy (CARS) was employed in all measurements. A novel laser interferometric system has been developed for real time in situ monitoring of the etch rate during the plasma etching. The two-beam-two-path optical set-up provides continuous etch rate measurements while plasma parameters are changing.

  14. Transient calorimetric diagnostics for plasma processing

    NASA Astrophysics Data System (ADS)

    Bornholdt, Sven; Kersten, Holger

    2013-08-01

    This paper reports on an improvement of the calorimetric method for the determination of energy fluxes from plasma towards substrates by using a transient technique. It provides a short overview of the traditional method used for characterization of plasma-wall-interactions during plasma processing. The mathematical framework of the method and possible implications are discussed. It is shown how the method can be improved to obtain additional and detailed information about the energy influx in a shorter measurement time. For this purpose, the probe bias (if applied), which has commonly been kept constant is varied like in Langmuir probe measurements. The experimental validation of the theoretical considerations emphasizes the potential of the method for control in plasma processing. The possibility how the passive calorimetric probe can be used in continuous measurements for process monitoring without any feedback loops used by other probes, is finally discussed.

  15. Semiclassical study of the quenching of excited-state fluorine atom by hydrogen molecule - Comparison between reactive and nonreactive processes

    NASA Technical Reports Server (NTRS)

    Yuan, J.-M.; Skuse, B. M.; Jaffe, R. L.; Komornicki, A.; Morokuma, K.; George, T. F.

    1980-01-01

    Semiclassical calculations are carried out for the quenching of excited-state fluorine atom by collinear collisions with hydrogen molecule. The overall quenching probability is the sum of two contributions: the reactive quenching probability associated with the formation of hydrogen fluoride and the nonreactive quenching probability leading to ground-state fluorine atom and hydrogen molecule. The reactive probability is greater in the threshold region of the collision energy, whereas the nonreactive probability dominates for energies above the threshold region.

  16. Effects of quenching, irradiation, and annealing processes on the radiation hardness of silica fiber cladding materials (I)

    NASA Astrophysics Data System (ADS)

    Wen, Jianxiang; Gong, Renxiang; Xiao, Zhongyin; Luo, Wenyun; Wu, Wenkai; Luo, Yanhua; Peng, Gang-ding; Pang, Fufei; Chen, Zhenyi; Wang, Tingyun

    2016-07-01

    Silica optical fiber cladding materials were experimentally treated by a series of processes. The treatments involved quenching, irradiation, followed by annealing and subsequent re-irradiation, and they were conducted in order to improve the radiation hardness. The microstructural properties of the treated materials were subsequently investigated. Following the treatment of the optical fiber cladding materials, the results from the electron spin resonance (ESR) analysis demonstrated that there was a significant decrease in the radiation-induced defect structures. The ESR signals became significantly weaker when the samples were annealed at 1000 °C in combination with re-irradiation. In addition, the microstructure changes within the silica optical fiber cladding material were also analyzed using Raman spectroscopy. The experimental results demonstrate that the Sisbnd Osbnd Si bending vibrations at ω3 = 800-820 cm-1 and ω4 = 1000-1200 cm-1 (with longitudinal optical (LO) and transverse optical (TO) splitting bands) were relatively unaffected by the quenching, irradiation, and annealing treatments. In particular, the annealing process resulted in the disappearance of the defect centers; however, the LO and TO modes at the ω3 and ω4 bands were relatively unchanged. With the additional support of the ESR test results, we can conclude that the combined treatment processes can significantly enhance the radiation hardness properties of the optical fiber cladding materials.

  17. Plasma characterization studies for materials processing

    SciTech Connect

    Pfender, E.; Heberlein, J.

    1995-12-31

    New applications for plasma processing of materials require a more detailed understanding of the fundamental processes occurring in the processing reactors. We have developed reactors offering specific advantages for materials processing, and we are using modeling and diagnostic techniques for the characterization of these reactors. The emphasis is in part set by the interest shown by industry pursuing specific plasma processing applications. In this paper we report on the modeling of radio frequency plasma reactors for use in materials synthesis, and on the characterization of the high rate diamond deposition process using liquid precursors. In the radio frequency plasma torch model, the influence of specific design changes such as the location of the excitation coil on the enthalpy flow distribution is investigated for oxygen and air as plasma gases. The diamond deposition with liquid precursors has identified the efficient mass transport in form of liquid droplets into the boundary layer as responsible for high growth, and the chemical properties of the liquid for the film morphology.

  18. Plasma processing of superconducting radio frequency cavities

    NASA Astrophysics Data System (ADS)

    Upadhyay, Janardan

    The development of plasma processing technology of superconducting radio frequency (SRF) cavities not only provides a chemical free and less expensive processing method, but also opens up the possibility for controlled modification of the inner surfaces of the cavity for better superconducting properties. The research was focused on the transition of plasma etching from two dimensional flat surfaces to inner surfaces of three dimensional (3D) structures. The results could be applicable to a variety of inner surfaces of 3D structures other than SRF cavities. Understanding the Ar/Cl2 plasma etching mechanism is crucial for achieving the desired modification of Nb SRF cavities. In the process of developing plasma etching technology, an apparatus was built and a method was developed to plasma etch a single cell Pill Box cavity. The plasma characterization was done with the help of optical emission spectroscopy. The Nb etch rate at various points of this cavity was measured before processing the SRF cavity. Cylindrical ring-type samples of Nb placed on the inner surface of the outer wall were used to measure the dependence of the process parameters on plasma etching. The measured etch rate dependence on the pressure, rf power, dc bias, temperature, Cl2 concentration and diameter of the inner electrode was determined. The etch rate mechanism was studied by varying the temperature of the outer wall, the dc bias on the inner electrode and gas conditions. In a coaxial plasma reactor, uniform plasma etching along the cylindrical structure is a challenging task due to depletion of the active radicals along the gas flow direction. The dependence of etch rate uniformity along the cylindrical axis was determined as a function of process parameters. The formation of dc self-biases due to surface area asymmetry in this type of plasma and its variation on the pressure, rf power and gas composition was measured. Enhancing the surface area of the inner electrode to reduce the

  19. On the difference between breakdown and quench voltages of argon plasma and its relation to 4p–4s atomic state transitions

    SciTech Connect

    Forati, Ebrahim Piltan, Shiva; Sievenpiper, Dan

    2015-02-02

    Using a relaxation oscillator circuit, breakdown (V{sub BD}) and quench (V{sub Q}) voltages of a DC discharge microplasma between two needle probes are measured. High resolution modified Paschen curves are obtained for argon microplasmas including a quench voltage curve representing the voltage at which the plasma turns off. It is shown that for a point to point microgap (e.g., the microgap between two needle probes) which describes many realistic microdevices, neither Paschen's law applies nor field emission is noticeable. Although normally V{sub BD} > V{sub Q,} it is observed that depending on environmental parameters of argon, such as pressure and the driving circuitry, plasma can exist in a different state with equal V{sub BD} and V{sub Q.} Using emission line spectroscopy, it is shown that V{sub BD} and V{sub Q} are equal if the atomic excitation by the electric field dipole moment dominantly leads to one of the argon's metastable states (4P{sub 5} in our study)

  20. Signal processing methods for MFE plasma diagnostics

    SciTech Connect

    Candy, J.V.; Casper, T.; Kane, R.

    1985-02-01

    The application of various signal processing methods to extract energy storage information from plasma diamagnetism sensors occurring during physics experiments on the Tandom Mirror Experiment-Upgrade (TMX-U) is discussed. We show how these processing techniques can be used to decrease the uncertainty in the corresponding sensor measurements. The algorithms suggested are implemented using SIG, an interactive signal processing package developed at LLNL.

  1. Coupled Model for Carbon Partitioning from Martensite into Austenite During the Quenching Process in Fe-C Steels

    NASA Astrophysics Data System (ADS)

    Liu, Peixing; Zhu, Bin; Wang, Yilin; Zhang, Yisheng

    2016-08-01

    In this paper, a coupled model for carbon partitioning from martensite into austenite during the quenching process in Fe-C steels is constructed where the carbon is permitted to partition while the martensite is continuously forming. A diffusion model of carbon at the `martensite/austenite interface' is created where the interface does not move during the carbon partitioning process, and the driving force for carbon partitioning originates from the chemical potential difference. The results show that the martensitic transformation and carbon partitioning affect each other, and that the cooling rate between the martensite start temperature ( M s) and room temperature has a major effect on the volume fraction of the final retained austenite. The simulation results are shown to be in good agreement with experiments.

  2. Microwave Plasma Sources for Gas Processing

    SciTech Connect

    Mizeraczyk, J.; Jasinski, M.; Dors, M.; Zakrzewski, Z.

    2008-03-19

    In this paper atmospheric pressure microwave discharge methods and devices used for producing the non-thermal plasmas for processing of gases are presented. The main part of the paper concerns the microwave plasma sources (MPSs) for environmental protection applications. A few types of the MPSs, i.e. waveguide-based surface wave sustained MPS, coaxial-line-based and waveguide-based nozzle-type MPSs, waveguide-based nozzleless cylinder-type MPS and MPS for microdischarges are presented. Also, results of the laboratory experiments on the plasma processing of several highly-concentrated (up to several tens percent) volatile organic compounds (VOCs), including Freon-type refrigerants, in the moderate (200-400 W) waveguide-based nozzle-type MPS (2.45 GHz) are presented. The results showed that the microwave discharge plasma fully decomposed the VOCs at relatively low energy cost. The energy efficiency of VOCs decomposition reached 1000 g/kWh. This suggests that the microwave discharge plasma can be a useful tool for environmental protection applications. In this paper also results of the use of the waveguide-based nozzleless cylinder-type MPS to methane reforming into hydrogen are presented.

  3. PLASMA EMISSION BY NONLINEAR ELECTROMAGNETIC PROCESSES

    SciTech Connect

    Ziebell, L. F.; Petruzzellis, L. T.; Gaelzer, R.; Yoon, P. H.; Pavan, J. E-mail: laripetruzzellis@yahoo.com.br E-mail: yoonp@umd.edu

    2015-06-20

    The plasma emission, or electromagnetic (EM) radiation at the plasma frequency and/or its harmonic(s), is generally accepted as the radiation mechanism responsible for solar type II and III radio bursts. Identification and characterization of these solar radio burst phenomena were done in the 1950s. Despite many decades of theoretical research since then, a rigorous demonstration of the plasma emission process based upon first principles was not available until recently, when, in a recent Letter, Ziebell et al. reported the first complete numerical solution of EM weak turbulence equations; thus, quantitatively analyzing the plasma emission process starting from the initial electron beam and the associated beam-plasma (or Langmuir wave) instability, as well as the subsequent nonlinear conversion of electrostatic Langmuir turbulence into EM radiation. In the present paper, the same problem is revisited in order to elucidate the detailed physical mechanisms that could not be reported in the brief Letter format. Findings from the present paper may be useful for interpreting observations and full-particle numerical simulations.

  4. Plasma Emission by Nonlinear Electromagnetic Processes

    NASA Astrophysics Data System (ADS)

    Ziebell, L. F.; Yoon, P. H.; Petruzzellis, L. T.; Gaelzer, R.; Pavan, J.

    2015-06-01

    The plasma emission, or electromagnetic (EM) radiation at the plasma frequency and/or its harmonic(s), is generally accepted as the radiation mechanism responsible for solar type II and III radio bursts. Identification and characterization of these solar radio burst phenomena were done in the 1950s. Despite many decades of theoretical research since then, a rigorous demonstration of the plasma emission process based upon first principles was not available until recently, when, in a recent Letter, Ziebell et al. reported the first complete numerical solution of EM weak turbulence equations; thus, quantitatively analyzing the plasma emission process starting from the initial electron beam and the associated beam-plasma (or Langmuir wave) instability, as well as the subsequent nonlinear conversion of electrostatic Langmuir turbulence into EM radiation. In the present paper, the same problem is revisited in order to elucidate the detailed physical mechanisms that could not be reported in the brief Letter format. Findings from the present paper may be useful for interpreting observations and full-particle numerical simulations.

  5. Secondary photon emission in plasma processing

    SciTech Connect

    Moshkalyov, S.; Machida, M.; Campos, D.; Dulkin, A.

    1997-05-01

    Optical emission spectroscopy with high spatial resolution was applied for the study of plasma{endash}material interaction in low-pressure reactive ion etching. Atomic and molecular emission by sputtered material has been found to be strongly localized near the surface. Excited particles are produced during sputtering by energetic ions, with the mechanisms being different for atoms and molecules. In atomic secondary photon emission, a cascade from highly excited levels is shown to be important. This method can be used as a probe during plasma processing. {copyright} {ital 1997 American Institute of Physics.}

  6. Plasma Emission by Weak Turbulence Processes

    NASA Astrophysics Data System (ADS)

    Ziebell, L. F.; Yoon, P. H.; Gaelzer, R.; Pavan, J.

    2014-11-01

    The plasma emission is the radiation mechanism responsible for solar type II and type III radio bursts. The first theory of plasma emission was put forth in the 1950s, but the rigorous demonstration of the process based upon first principles had been lacking. The present Letter reports the first complete numerical solution of electromagnetic weak turbulence equations. It is shown that the fundamental emission is dominant and unless the beam speed is substantially higher than the electron thermal speed, the harmonic emission is not likely to be generated. The present findings may be useful for validating reduced models and for interpreting particle-in-cell simulations.

  7. Solar terrestrial coupling through space plasma processes

    SciTech Connect

    Birn, J.

    2000-12-01

    This is the final report of a three-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). The project investigates plasma processes that govern the interaction between the solar wind, charged particles ejected from the sun, and the earth's magnetosphere, the region above the ionosphere governed by the terrestrial magnetic field. Primary regions of interest are the regions where different plasma populations interact with each other. These are regions of particularly dynamic plasma behavior, associated with magnetic flux and energy transfer and dynamic energy release. The investigations concerned charged particle transport and energization, and microscopic and macroscopic instabilities in the magnetosphere and adjacent regions. The approaches combined space data analysis with theory and computer simulations.

  8. Analysis and experiments on thermal plasma processing for ultrafine powder synthesis of aluminium nitride

    SciTech Connect

    Ahn, H.; Hur, M.; Hong, S.H.

    1996-12-31

    Plasma synthesis experiments for producing ultrafine powders of aluminum nitride (AlN) are carried out using a non-transferred dc plasma torch of which jet flame can vaporize the aluminum powders injected into it to make the chemical reaction with nitrogen gas. For predicting the optimum processing parameters (the size, injected location and velocity of Al powders, and the ratio of nitrogen to argon arc gases), the trajectory and the evaporation state of an Al particle arc found by solving momentum and heat transfer equations. In addition, equilibrium chemical compositions are analyzed by the Gibbs free-energy minimization method to know the temperatures at which AlN synthesis occurs dominantly. A synthesis system consisting of a plasma torch, a reactor and a quenching chamber has been built for synthesis and quenching process of ultrafine powders of AlN. A fully-saturated fractional factorial test is employed to determine optimum process conditions for input power to the torch and flow rates of arc, carrier and reaction gases.

  9. Experimental and Numerical Studies on the Formability of Materials in Hot Stamping and Cold Die Quenching Processes

    SciTech Connect

    Li, N.; Mohamed, M. S.; Cai, J.; Lin, J.; Balint, D.; Dean, T. A.

    2011-05-04

    Formability of steel and aluminium alloys in hot stamping and cold die quenching processes is studied in this research. Viscoplastic-damage constitutive equations are developed and determined from experimental data for the prediction of viscoplastic flow and ductility of the materials. The determined unified constitutive equations are then implemented into the commercial Finite Element code Abaqus/Explicit via a user defined subroutine, VUMAT. An FE process simulation model and numerical procedures are established for the modeling of hot stamping processes for a spherical part with a central hole. Different failure modes (failure takes place either near the central hole or in the mid span of the part) are obtained. To validate the simulation results, a test programme is developed, a test die set has been designed and manufactured, and tests have been carried out for the materials with different forming rates. It has been found that very close agreements between experimental and numerical process simulation results are obtained for the ranges of temperatures and forming rates carried out.

  10. Physical processes in spin polarized plasmas

    SciTech Connect

    Kulsrud, R.M.; Valeo, E.J.; Cowley, S.

    1984-05-01

    If the plasma in a nuclear fusion reactor is polarized, the nuclear reactions are modified in such a way as to enhance the reactor performance. We calculate in detail the modification of these nuclear reactions by different modes of polarization of the nuclear fuel. We also consider in detail the various physical processes that can lead to depolarization and show that they are by and large slow enough that a high degree of polarization can be maintained.

  11. Suspension Plasma Spraying: Process Characteristics and Applications

    NASA Astrophysics Data System (ADS)

    Vaßen, Robert; Kaßner, Holger; Mauer, Georg; Stöver, Detlev

    2010-01-01

    Suspension plasma spraying (SPS) offers the manufacture of unique microstructures which are not possible with conventional powdery feedstock. Due to the considerably smaller size of the droplets and also the further fragmentation of these in the plasma jet, the attainable microstructural features like splat and pore sizes can be downsized to the nanometer range. Our present understanding of the deposition process including injection, suspension plasma plume interaction, and deposition will be outlined. The drawn conclusions are based on analysis of the coating microstructures in combination with particle temperature and velocity measurements as well as enthalpy probe investigations. The last measurements with the water cooled stagnation probe gives valuable information on the interaction of the carrier fluid with the plasma plume. Meanwhile, different areas of application of SPS coatings are known. In this paper, the focus will be on coatings for energy systems. Thermal barrier coatings (TBCs) for modern gas turbines are one important application field. SPS coatings offer the manufacture of strain-tolerant, segmented TBCs with low thermal conductivity. In addition, highly reflective coatings, which reduce the thermal load of the parts from radiation, can be produced. Further applications of SPS coatings as cathode layers in solid oxide fuel cells (SOFC) and for photovoltaic (PV) applications will be presented.

  12. Automated Plasma Spray (APS) process feasibility study

    NASA Technical Reports Server (NTRS)

    Fetheroff, C. W.; Derkacs, T.; Matay, I. M.

    1981-01-01

    An automated plasma spray (APS) process was developed to apply two layer (NiCrAlY and ZrO2-12Y2O3) thermal barrier coatings to aircraft and stationary gas turbine engine blade airfoils. The APS process hardware consists of four subsystems: a mechanical positioning subsystem incorporating two interlaced six degree of freedom assemblies (one for coating deposition and one for coating thickness monitoring); a noncoherent optical metrology subsystem (for in process gaging of the coating thickness buildup at specified points on the specimen); a microprocessor based adaptive system controller (to achieve the desired overall thickness profile on the specimen); and commerical plasma spray equipment. Over fifty JT9D first stage aircraft turbine blade specimens, ten W501B utility turbine blade specimens and dozens of cylindrical specimens were coated with the APS process in preliminary checkout and evaluation studies. The best of the preliminary turbine blade specimens achieved an overall coating thickness uniformity of 53 micrometers (2.1 mils), much better than is achievable manually. Comparative evaluations of coating thickness uniformity for manually sprayed and APS coated specimens were performed. One of the preliminary turbine blade evaluation specimens was subjected to a torch test and metallographic evaluation. Some cylindrical specimens coated with the APS process survived up to 2000 cycles in subsequent burner rig testing.

  13. Current problems in plasma spray processing

    SciTech Connect

    Berndt, C.C.; Brindley, W.; Goland, A.N.; Herman, H.; Houck, D.L.; Jones, K.; Miller, R.A.; Neiser, R.; Riggs, W.; Sampath, S.; Smith, M.; Spanne, P. . Thermal Spray Lab.)

    1991-01-01

    This detailed report summarizes 8 contributions from a thermal spray conference that was held in late 1991 at Brookhaven National Laboratory (Upton, Long Island, NY, USA). The subject of Plasma Spray Processing'' is presented under subject headings of Plasma-particle interactions, Deposit formation dynamics, Thermal properties of thermal barrier coatings, Mechanical properties of coatings, Feed stock materials, Porosity: An integrated approach, Manufacture of intermetallic coatings, and Synchrotron x-ray microtomographic methods for thermal spray materials. Each section is intended to present a concise statement of a specific practical and/or scientific problem, then describe current work that is being performed to investigate this area, and finally to suggest areas of research that may be fertile for future activity.

  14. Current problems in plasma spray processing

    SciTech Connect

    Berndt, C.C.; Brindley, W.; Goland, A.N.; Herman, H.; Houck, D.L.; Jones, K.; Miller, R.A.; Neiser, R.; Riggs, W.; Sampath, S.; Smith, M.; Spanne, P.

    1991-12-31

    This detailed report summarizes 8 contributions from a thermal spray conference that was held in late 1991 at Brookhaven National Laboratory (Upton, Long Island, NY, USA). The subject of ``Plasma Spray Processing`` is presented under subject headings of Plasma-particle interactions, Deposit formation dynamics, Thermal properties of thermal barrier coatings, Mechanical properties of coatings, Feed stock materials, Porosity: An integrated approach, Manufacture of intermetallic coatings, and Synchrotron x-ray microtomographic methods for thermal spray materials. Each section is intended to present a concise statement of a specific practical and/or scientific problem, then describe current work that is being performed to investigate this area, and finally to suggest areas of research that may be fertile for future activity.

  15. Automated process control for plasma etching

    NASA Astrophysics Data System (ADS)

    McGeown, Margaret; Arshak, Khalil I.; Murphy, Eamonn

    1992-06-01

    This paper discusses the development and implementation of a rule-based system which assists in providing automated process control for plasma etching. The heart of the system is to establish a correspondence between a particular data pattern -- sensor or data signals -- and one or more modes of failure, i.e., a data-driven monitoring approach. The objective of this rule based system, PLETCHSY, is to create a program combining statistical process control (SPC) and fault diagnosis to help control a manufacturing process which varies over time. This can be achieved by building a process control system (PCS) with the following characteristics. A facility to monitor the performance of the process by obtaining and analyzing the data relating to the appropriate process variables. Process sensor/status signals are input into an SPC module. If trends are present, the SPC module outputs the last seven control points, a pattern which is represented by either regression or scoring. The pattern is passed to the rule-based module. When the rule-based system recognizes a pattern, it starts the diagnostic process using the pattern. If the process is considered to be going out of control, advice is provided about actions which should be taken to bring the process back into control.

  16. Tokamak plasma modelling and atomic processes

    NASA Astrophysics Data System (ADS)

    Kawamura, T.

    1986-06-01

    Topics addressed include: particle control in a tokomak device; ionizing and recombining plasmas; effects of data accuracy on tokamak impurity transport modeling; plasma modeling of tokamaks; and ultraviolet and X-ray spectroscopy of tokamak plasmas.

  17. LoCuSS: THE SLOW QUENCHING OF STAR FORMATION IN CLUSTER GALAXIES AND THE NEED FOR PRE-PROCESSING

    SciTech Connect

    Haines, C. P.; Pereira, M. J.; Egami, E.; Rawle, T. D.; Smith, G. P.; Ziparo, F.; McGee, S. L.; Babul, A.; Finoguenov, A.; Okabe, N.; Moran, S. M.

    2015-06-10

    We present a study of the spatial distribution and kinematics of star-forming galaxies in 30 massive clusters at 0.15 < z < 0.30, combining wide-field Spitzer 24 μm and GALEX near-ultraviolet imaging with highly complete spectroscopy of cluster members. The fraction (f{sub SF}) of star-forming cluster galaxies rises steadily with cluster-centric radius, increasing fivefold by 2r{sub 200}, but remains well below field values even at 3r{sub 200}. This suppression of star formation at large radii cannot be reproduced by models in which star formation is quenched in infalling field galaxies only once they pass within r{sub 200} of the cluster, but is consistent with some of them being first pre-processed within galaxy groups. Despite the increasing f{sub SF}-radius trend, the surface density of star-forming galaxies actually declines steadily with radius, falling ∼15× from the core to 2r{sub 200}. This requires star formation to survive within recently accreted spirals for 2–3 Gyr to build up the apparent over-density of star-forming galaxies within clusters. The velocity dispersion profile of the star-forming galaxy population shows a sharp peak of 1.44 σ{sub ν} at 0.3r{sub 500}, and is 10%–35% higher than that of the inactive cluster members at all cluster-centric radii, while their velocity distribution shows a flat, top-hat profile within r{sub 500}. All of these results are consistent with star-forming cluster galaxies being an infalling population, but one that must also survive ∼0.5–2 Gyr beyond passing within r{sub 200}. By comparing the observed distribution of star-forming galaxies in the stacked caustic diagram with predictions from the Millennium simulation, we obtain a best-fit model in which star formation rates decline exponentially on quenching timescales of 1.73 ± 0.25 Gyr upon accretion into the cluster.

  18. LoCuSS: The Slow Quenching of Star Formation in Cluster Galaxies and the Need for Pre-processing

    NASA Astrophysics Data System (ADS)

    Haines, C. P.; Pereira, M. J.; Smith, G. P.; Egami, E.; Babul, A.; Finoguenov, A.; Ziparo, F.; McGee, S. L.; Rawle, T. D.; Okabe, N.; Moran, S. M.

    2015-06-01

    We present a study of the spatial distribution and kinematics of star-forming galaxies in 30 massive clusters at 0.15 < z < 0.30, combining wide-field Spitzer 24 μm and GALEX near-ultraviolet imaging with highly complete spectroscopy of cluster members. The fraction (fSF) of star-forming cluster galaxies rises steadily with cluster-centric radius, increasing fivefold by 2r200, but remains well below field values even at 3r200. This suppression of star formation at large radii cannot be reproduced by models in which star formation is quenched in infalling field galaxies only once they pass within r200 of the cluster, but is consistent with some of them being first pre-processed within galaxy groups. Despite the increasing fSF-radius trend, the surface density of star-forming galaxies actually declines steadily with radius, falling ˜15× from the core to 2r200. This requires star formation to survive within recently accreted spirals for 2-3 Gyr to build up the apparent over-density of star-forming galaxies within clusters. The velocity dispersion profile of the star-forming galaxy population shows a sharp peak of 1.44 σν at 0.3r500, and is 10%-35% higher than that of the inactive cluster members at all cluster-centric radii, while their velocity distribution shows a flat, top-hat profile within r500. All of these results are consistent with star-forming cluster galaxies being an infalling population, but one that must also survive ˜0.5-2 Gyr beyond passing within r200. By comparing the observed distribution of star-forming galaxies in the stacked caustic diagram with predictions from the Millennium simulation, we obtain a best-fit model in which star formation rates decline exponentially on quenching timescales of 1.73 ± 0.25 Gyr upon accretion into the cluster.

  19. Renormalization of the jet-quenching parameter

    NASA Astrophysics Data System (ADS)

    Blaizot, Jean-Paul; Mehtar-Tani, Yacine

    2014-09-01

    We study the radiative processes that affect the propagation of a high energy gluon in a dense medium, such as a quark-gluon plasma. In particular, we investigate the role of the large double logarithmic corrections, ∼αsln2 L /τ0, that were recently identified in the study of p⊥-broadening by Liou, Mueller and Wu. We show that these large corrections can be reabsorbed in a renormalization of the jet quenching parameter controlling both momentum broadening and energy loss. We argue that the probabilistic description of these phenomena remains valid, in spite of the large non-locality in time of the radiative corrections. The renormalized jet-quenching parameter is enhanced compared to its standard perturbative estimate. As a particular consequence, the radiative energy loss scales with medium size L as L 2 + γ, with γ = 2√{αsNc / π }, as compared to the standard scaling in L2.

  20. Removal of pollutants by plasma catalytic processes

    NASA Astrophysics Data System (ADS)

    Pasquiers, S.

    2004-12-01

    Removal of molecular atmospheric pollutants by non-thermal plasmas is under study since the beginning of the eighties. It has been shown that pulsed electrical discharges, such as dielectric barrier or corona discharges, are powerful means to eliminate Volatile Organic Compounds (VOCs) from the ambient air, or to treat flue gases which contain nitrogen oxide. However it is now recognised that, for several pollutants, the use of the plasma alone does not allow a complete elimination of the undesirable molecule. For example NO is oxidised in the air plasma to form other oxides like NO{2} and N{2}O{5}, and reactions of oxygen atoms or hydroxyl radicals produced by the discharge with VOCs can lead not only to H{2}O and CO{2} but to a number of by-products following the partial oxidation of the molecule, which can be as undesirable than the compound to be initially removed from effluents. This is particularly the case when the electrical energy deposited in the gas flow must be kept as low as possible in order to design a low energy cost equipment. As a result addition of a catalyst together with the pulsed discharge is now investigated in various laboratories in order to achieve a complete oxidation of VOCs, i.e. the so-called de-COV process, or a complete reduction of NOX (NO and NO{2}) to produce N{2} and O{2}, i.e. the so-called de-NOX process, at low energy consumption. This paper is a short review of works which have been done these last years in that domain, specifically on NOX and some selected VOC molecules.

  1. Offgas emissions from the plasma hearth process

    SciTech Connect

    Batdorf, J.A.; Geimer, R.M.; Hassel, G.R.; Wolfe, W.P.

    1996-12-31

    The Department of Energy is currently evaluating SAIC`s Plasma Hearth Process (PHP) for use as a new method of treating mixtures of radioactive and hazardous wastes. The PHP has been specifically designed for the treatment of both low-level and transuranic mixed waste. These mixed wastes range in composition from non-combustible inorganic sludge wastes to highly combustible plastic and organic sludge wastes. The unique aspect of the PHP technology is its ability to treat this wide range of materials even when combined as a poorly characterized heterogeneous mixture. The PHP uses a plasma-arc torch to volatilize the organic components of the waste and vitrify residual inert materials. Hazardous organic constituents are destroyed in a secondary combustion chamber. Offgas from the process is thoroughly cleaned by state-of-the-art air pollution control equipment. This paper describes the results of the {open_quotes}proof-of-principle{close_quotes} testing of this technology and focuses on the results of the analysis of the offgas emissions. The results demonstrate that the PHP completely destroys organic material; and that the vitrified residual`s leach characteristics are comparable to glass formulated for stabilization of high-level radioactive waste. 10 refs., 1 fig., 13 tabs.

  2. Feasibility Study for a Plasma Dynamo Facility to Investigate Fundamental Processes in Plasma Astrophysics. Final report

    SciTech Connect

    Forest, Cary B.

    2013-09-19

    The scientific equipment purchased on this grant was used on the Plasma Dynamo Prototype Experiment as part of Professor Forest's feasibility study for determining if it would be worthwhile to propose building a larger plasma physics experiment to investigate various fundamental processes in plasma astrophysics. The initial research on the Plasma Dynamo Prototype Experiment was successful so Professor Forest and Professor Ellen Zweibel at UW-Madison submitted an NSF Major Research Instrumentation proposal titled "ARRA MRI: Development of a Plasma Dynamo Facility for Experimental Investigations of Fundamental Processes in Plasma Astrophysics." They received funding for this project and the Plasma Dynamo Facility also known as the "Madison Plasma Dynamo Experiment" was constructed. This experiment achieved its first plasma in the fall of 2012 and U.S. Dept. of Energy Grant No. DE-SC0008709 "Experimental Studies of Plasma Dynamos," now supports the research.

  3. Physical processes associated with current collection by plasma contactors

    NASA Technical Reports Server (NTRS)

    Katz, Ira; Davis, Victoria A.

    1990-01-01

    Recent flight data confirms laboratory observations that the release of neutral gas increases plasma sheath currents. Plasma contactors are devices which release a partially ionized gas in order to enhance the current flow between a spacecraft and the space plasma. Ionization of the expellant gas and the formation of a double layer between the anode plasma and the space plasma are the dominant physical processes. A theory is presented of the interaction between the contactor plasma and the background plasma. The conditions for formation of a double layer between the two plasmas are derived. Double layer formation is shown to be a consequence of the nonlinear response of the plasmas to changes in potential. Numerical calculations based upon this model are compared with laboratory measurements of current collection by hollow cathode-based plasma contactors.

  4. Plasma Discharge Process in a Pulsed Diaphragm Discharge System

    NASA Astrophysics Data System (ADS)

    Duan, Jianjin; Hu, Jue; Zhang, Chao; Wen, Yuanbin; Meng, Yuedong; Zhang, Chengxu

    2014-12-01

    As one of the most important steps in wastewater treatment, limited study on plasma discharge process is a key challenge in the development of plasma applications. In this study, we focus on the plasma discharge process of a pulsed diaphragm discharge system. According to the analysis, the pulsed diaphragm discharge proceeds in seven stages: (1) Joule heating and heat exchange stage; (2) nucleated site formation; (3) plasma generation (initiation of the breakdown stage); (4) avalanche growth and plasma expansion; (5) plasma contraction; (6) termination of the plasma discharge; and (7) heat exchange stage. From this analysis, a critical voltage criterion for breakdown is obtained. We anticipate this finding will provide guidance for a better application of plasma discharges, especially diaphragm plasma discharges.

  5. Lagrangian coherent structures and plasma transport processes

    NASA Astrophysics Data System (ADS)

    Falessi, M. V.; Pegoraro, F.; Schep, T. J.

    2015-10-01

    > A dynamical system framework is used to describe transport processes in plasmas embedded in a magnetic field. For periodic systems with one degree of freedom, the Poincaré map provides a splitting of the phase space into regions where particles have different kinds of motion: periodic, quasi-periodic or chaotic. The boundaries of these regions are transport barriers, i.e. a trajectory cannot cross such boundaries throughout the evolution of the system. Lagrangian coherent structures generalize this method to systems with the most general time dependence, splitting the phase space into regions with different qualitative behaviours. This leads to the definition of finite-time transport barriers, i.e. trajectories cannot cross the barrier for a finite amount of time. This methodology can be used to identify fast recirculating regions in the dynamical system and to characterize the transport between them.

  6. Method and apparatus for monitoring plasma processing operations

    DOEpatents

    Smith, Jr., Michael Lane; Stevenson, Joel O'Don; Ward, Pamela Peardon Denise

    2001-01-01

    The invention generally relates to various aspects of a plasma process, and more specifically the monitoring of such plasma processes. One aspect relates in at least some manner to calibrating or initializing a plasma monitoring assembly. This type of calibration may be used to address wavelength shifts, intensity shifts, or both associated with optical emissions data obtained on a plasma process. A calibration light may be directed at a window through which optical emissions data is being obtained to determine the effect, if any, that the inner surface of the window is having on the optical emissions data being obtained therethrough, the operation of the optical emissions data gathering device, or both. Another aspect relates in at least some manner to various types of evaluations which may be undertaken of a plasma process which was run, and more typically one which is currently being run, within the processing chamber. Plasma health evaluations and process identification through optical emissions analysis are included in this aspect. Yet another aspect associated with the present invention relates in at least some manner to the endpoint of a plasma process (e.g., plasma recipe, plasma clean, conditioning wafer operation) or discrete/discernible portion thereof (e.g., a plasma step of a multiple step plasma recipe). A final aspect associated with the present invention relates to how one or more of the above-noted aspects may be implemented into a semiconductor fabrication facility, such as the distribution of wafers to a wafer production system.

  7. Method and apparatus for monitoring plasma processing operations

    DOEpatents

    Smith, Jr., Michael Lane; Stevenson, Joel O'Don; Ward, Pamela Peardon Denise

    2002-07-16

    The invention generally relates to various aspects of a plasma process, and more specifically the monitoring of such plasma processes. One aspect relates in at least some manner to calibrating or initializing a plasma monitoring assembly. This type of calibration may be used to address wavelength shifts, intensity shifts, or both associated with optical emissions data obtained on a plasma process. A calibration light may be directed at a window through which optical emissions data is being obtained to determine the effect, if any, that the inner surface of the window is having on the optical emissions data being obtained therethrough, the operation of the optical emissions data gathering device, or both. Another aspect relates in at least some manner to various types of evaluations which may be undertaken of a plasma process which was run, and more typically one which is currently being run, within the processing chamber. Plasma health evaluations and process identification through optical emissions analysis are included in this aspect. Yet another aspect associated with the present invention relates in at least some manner to the endpoint of a plasma process (e.g., plasma recipe, plasma clean, conditioning wafer operation) or discrete/discernible portion thereof (e.g., a plasma step of a multiple step plasma recipe). A final aspect associated with the present invention relates to how one or more of the above-noted aspects may be implemented into a semiconductor fabrication facility, such as the distribution of wafers to a wafer production system.

  8. Method and apparatus for monitoring plasma processing operations

    DOEpatents

    Smith, Jr., Michael Lane; Stevenson, Joel O'Don; Ward, Pamela Peardon Denise

    2000-01-01

    The invention generally relates to various aspects of a plasma process, and more specifically the monitoring of such plasma processes. One aspect relates in at least some manner to calibrating or initializing a plasma monitoring assembly. This type of calibration may be used to address wavelength shifts, intensity shifts, or both associated with optical emissions data obtained on a plasma process. A calibration light may be directed at a window through which optical emissions data is being obtained to determine the effect, if any, that the inner surface of the window is having on the optical emissions data being obtained therethrough, the operation of the optical emissions data gathering device, or both. Another aspect relates in at least some manner to various types of evaluations which may be undertaken of a plasma process which was run, and more typically one which is currently being run, within the processing chamber. Plasma health evaluations and process identification through optical emissions analysis are included in this aspect. Yet another aspect associated with the present invention relates in at least some manner to the endpoint of a plasma process (e.g., plasma recipe, plasma clean, conditioning wafer operation) or discrete/discernible portion thereof (e.g., a plasma step of a multiple step plasma recipe). A final aspect associated with the present invention relates to how one or more of the above-noted aspects may be implemented into a semiconductor fabrication facility, such as the distribution of wafers to a wafer production system.

  9. Method and apparatus for monitoring plasma processing operations

    DOEpatents

    Smith, Jr., Michael Lane; Stevenson, Joel O'Don; Ward, Pamela Peardon Denise

    2001-01-01

    The invention generally relates to various aspects of a plasma process, and more specifically the monitoring of such plasma processes. One aspect relates in at least some manner to calibrating or initializing a plasma monitoring assembly. This type of calibration may be used to address wavelength shifts, intensity shifts, or both associated with optical emissions data obtained on a plasma process. A calibration light may be directed at a window through which optical emissions data is being obtained to determine the effect, if any, that the inner surface of the window is having on the optical emissions data being obtained therethrough, the operation of the optical emissions data gathering device, or both. Another aspect relates in at least some manner to various types of evaluations which may be undertaken of a plasma process which was run, and more typically one which is currently being run, within the processing chamber. Plasma health evaluations and process identification through optical emissions analysis are included in this aspect. Yet another aspect associated with the present invention relates in at least some manner to the endpoint of a plasma process (e.g., plasma recipe, plasma clean, conditioning wafer operation) or discrete/discemible portion thereof (e.g., a plasma step of a multiple step plasma recipe). A final aspect associated with the present invention relates to how one or more of the above-noted aspects may be implemented into a semiconductor fabrication facility, such as the distribution of wafers to a wafer production system.

  10. High Power Helicon Plasma Source for Plasma Processing

    NASA Astrophysics Data System (ADS)

    Prager, James; Ziemba, Timothy; Miller, Kenneth E.

    2015-09-01

    Eagle Harbor Technologies (EHT), Inc. is developing a high power helicon plasma source. The high power nature and pulsed neutral gas make this source unique compared to traditional helicon source. These properties produce a plasma flow along the magnetic field lines, and therefore allow the source to be decoupled from the reaction chamber. Neutral gas can be injected downstream, which allows for precision control of the ion-neutral ratio at the surface of the sample. Although operated at high power, the source has demonstrated very low impurity production. This source has applications to nanoparticle productions, surface modification, and ionized physical vapor deposition.

  11. Effect of background plasma nonlinearities on dissipation processes in plasmas

    NASA Astrophysics Data System (ADS)

    Nekrasov, F. M.; Elfimov, A. G.; de Azevedo, C. A.; de Assis, A. S.

    1999-01-01

    The Coulomb collision effect on the bounce-resonance dissipation is considered for toroidal magnetized plasmas. The solution of the Vlasov equation with a simplified Fokker-Planck collision operator is presented. The parallel components of the dielectric tensor are obtained. A collisionless limit of wave dissipation is found.

  12. Preliminary Hazards Analysis Plasma Hearth Process

    SciTech Connect

    Aycock, M.; Coordes, D.; Russell, J.; TenBrook, W.; Yimbo, P.

    1993-11-01

    This Preliminary Hazards Analysis (PHA) for the Plasma Hearth Process (PHP) follows the requirements of United States Department of Energy (DOE) Order 5480.23 (DOE, 1992a), DOE Order 5480.21 (DOE, 1991d), DOE Order 5480.22 (DOE, 1992c), DOE Order 5481.1B (DOE, 1986), and the guidance provided in DOE Standards DOE-STD-1027-92 (DOE, 1992b). Consideration is given to ft proposed regulations published as 10 CFR 830 (DOE, 1993) and DOE Safety Guide SG 830.110 (DOE, 1992b). The purpose of performing a PRA is to establish an initial hazard categorization for a DOE nuclear facility and to identify those processes and structures which may have an impact on or be important to safety. The PHA is typically performed during and provides input to project conceptual design. The PRA then is followed by a Preliminary Safety Analysis Report (PSAR) performed during Title I and II design. This PSAR then leads to performance of the Final Safety Analysis Report performed during construction, testing, and acceptance and completed before routine operation. Radiological assessments indicate that a PHP facility, depending on the radioactive material inventory, may be an exempt, Category 3, or Category 2 facility. The calculated impacts would result in no significant impact to offsite personnel or the environment. Hazardous material assessments indicate that a PHP facility will be a Low Hazard facility having no significant impacts either onsite or offsite to personnel and the environment.

  13. Two-Step Plasma Process for Cleaning Indium Bonding Bumps

    NASA Technical Reports Server (NTRS)

    Greer, Harold F.; Vasquez, Richard P.; Jones, Todd J.; Hoenk, Michael E.; Dickie, Matthew R.; Nikzad, Shouleh

    2009-01-01

    A two-step plasma process has been developed as a means of removing surface oxide layers from indium bumps used in flip-chip hybridization (bump bonding) of integrated circuits. The two-step plasma process makes it possible to remove surface indium oxide, without incurring the adverse effects of the acid etching process.

  14. Cool flame quench distances

    NASA Technical Reports Server (NTRS)

    Ryason, P. R.; Hirsch, E.

    1974-01-01

    The results of a brief experimental investigation are presented which confirm the expectation that cool flame quenching distances should be larger than hot flame quenching distances. It is also discovered that whereas quenching distances for hot flames reach their minimum values near stoichiometric conditions, cool flame quenching distances are least under rich conditions. Rich conditions are well known to favor cool flame formation.

  15. Studies on plasma processing of blue dust

    NASA Astrophysics Data System (ADS)

    Samal, S. K.; P, Sindhoora L.; Mishra, S. C.; Mishra, B.

    2015-02-01

    Plasma smelting was carried out using blue dust and petroleum coke mixtures for five different compositions. By altering percentage of reductant and type of plasma forming gas, recovery rate and degree of metallization were calculated in order to examine the extent of reduction of blue dust. The products were characterized by XRD and optical microscopy techniques. The results of these investigations exhibited that highest degree of metallization and recovery rate of about 98% and 86% respectively, were achieved for nitrogen plasma smelted products.

  16. Atomic processes in high-density plasmas

    NASA Astrophysics Data System (ADS)

    More, R. M.

    Dense atomic plasmas such as that produced in inertial confinement fusion are reviewed. The target implosion physics along with the associated atomic physics, i.e., free electron collision phenomena, electron states I, electron states II, and nonequilibrum plasma states are described.

  17. Cold plasma as a food processing technology

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cold plasma uses energetic, reactive gases to inactivate contaminating microbes on a variety of foods, such as meats, poultry and fruits and vegetables. The primary modes of action are reactive chemical species and ultraviolet light. Various cold plasma systems are under development, operating at am...

  18. Research on atmospheric pressure plasma processing sewage

    NASA Astrophysics Data System (ADS)

    Song, Gui-cai; Na, Yan-xiang; Dong, Xiao-long; Sun, Xiao-liang

    2013-08-01

    The water pollution has become more and more serious with the industrial progress and social development, so it become a worldwide leading environmental management problem to human survival and personal health, therefore, countries are looking for the best solution. Generally speaking, in this paper the work has the following main achievements and innovation: (1) Developed a new plasma device--Plasma Water Bed. (2) At atmospheric pressure condition, use oxygen, nitrogen, argon and helium as work gas respectively, use fiber spectrometer to atmospheric pressure plasma discharge the emission spectrum of measurement, due to the different work gas producing active particle is different, so can understand discharge, different particle activity, in the treatment of wastewater, has the different degradation effects. (3) Methyl violet solution treatment by plasma water bed. Using plasma drafting make active particles and waste leachate role, observe the decolorization, measurement of ammonia nitrogen removal.

  19. Thermomechanical processing of plasma sprayed intermetallic sheets

    DOEpatents

    Hajaligol, Mohammad R.; Scorey, Clive; Sikka, Vinod K.; Deevi, Seetharama C.; Fleischhauer, Grier; Lilly, Jr., A. Clifton; German, Randall M.

    2001-01-01

    A powder metallurgical process of preparing a sheet from a powder having an intermetallic alloy composition such as an iron, nickel or titanium aluminide. The sheet can be manufactured into electrical resistance heating elements having improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The iron aluminide has an entirely ferritic microstructure which is free of austenite and can include, in weight %, 4 to 32% Al, and optional additions such as .ltoreq.1% Cr, .gtoreq.0.05% Zr .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Ni, .ltoreq.0.75% C, .ltoreq.0.1% B, .ltoreq.1% submicron oxide particles and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, and/or .ltoreq.3% Cu. The process includes forming a non-densified metal sheet by consolidating a powder having an intermetallic alloy composition such as by roll compaction, tape casting or plasma spraying, forming a cold rolled sheet by cold rolling the non-densified metal sheet so as to increase the density and reduce the thickness thereof and annealing the cold rolled sheet. The powder can be a water, polymer or gas atomized powder which is subjecting to sieving and/or blending with a binder prior to the consolidation step. After the consolidation step, the sheet can be partially sintered. The cold rolling and/or annealing steps can be repeated to achieve the desired sheet thickness and properties. The annealing can be carried out in a vacuum furnace with a vacuum or inert atmosphere. During final annealing, the cold rolled sheet recrystallizes to an average grain size of about 10 to 30 .mu.m. Final stress relief annealing can be carried out in the B2 phase temperature range.

  20. Annular vortex merging processes in non-neutral electron plasmas

    SciTech Connect

    Kaga, Chikato Ito, Kiyokazu; Higaki, Hiroyuki; Okamoto, Hiromi

    2015-06-29

    Non-neutral electron plasmas in a uniform magnetic field are investigated experimentally as a two dimensional (2D) fluid. Previously, it was reported that 2D phase space volume increases during a vortex merging process with viscosity. However, the measurement was restricted to a plasma with a high density. Here, an alternative method is introduced to evaluate a similar process for a plasma with a low density.

  1. Plasma heating for containerless and microgravity materials processing

    NASA Technical Reports Server (NTRS)

    Leung, Emily W. (Inventor); Man, Kin F. (Inventor)

    1994-01-01

    A method for plasma heating of levitated samples to be used in containerless microgravity processing is disclosed. A sample is levitated by electrostatic, electromagnetic, aerodynamic, or acoustic systems, as is appropriate for the physical properties of the particular sample. The sample is heated by a plasma torch at atmospheric pressure. A ground plate is provided to help direct the plasma towards the sample. In addition, Helmholtz coils are provided to produce a magnetic field that can be used to spiral the plasma around the sample. The plasma heating system is oriented such that it does not interfere with the levitation system.

  2. Method and apparatus for monitoring plasma processing operations

    DOEpatents

    Smith, Jr., Michael Lane; Ward, Pamela Denise Peardon; Stevenson, Joel O'Don

    2002-01-01

    The invention generally relates to various aspects of a plasma process, and more specifically the monitoring of such plasma processes. One aspect relates in at least some manner to calibrating or initializing a plasma monitoring assembly. This type of calibration may be used to address wavelength shifts, intensity shifts, or both associated with optical emissions data obtained on a plasma process. A calibration light may be directed at a window through which optical emissions data is being obtained to determine the effect, if any, that the inner surface of the window is having on the optical emissions data being obtained therethrough, the operation of the optical emissions data gathering device, or both. Another aspect relates in at least some manner to various types of evaluations which may be undertaken of a plasma process which was run, and more typically one which is currently being run, within the processing chamber. Plasma health evaluations and process identification through optical emissions analysis are included in this aspect. Yet another aspect associated with the present invention relates in at least some manner to the endpoint of a plasma process (e.g., plasma recipe, plasma clean, conditioning wafer operation) or discrete/discernible portion thereof (e.g., a plasma step of a multiple step plasma recipe). Another aspect associated with the present invention relates to how one or more of the above-noted aspects may be implemented into a semiconductor fabrication facility, such as the distribution of wafers to a wafer production system. A final aspect of the present invention relates to a network a plurality of plasma monitoring systems, including with remote capabilities (i.e., outside of the clean room).

  3. Advances in Plasma Process Equipment Development using Plasma and Electromagnetics Modeling

    NASA Astrophysics Data System (ADS)

    Agarwal, Ankur

    2013-10-01

    Plasma processing is widely used in the semiconductor industry for thin film etching and deposition, modification of near-surface material, and cleaning. In particular, the challenges for plasma etching have increased as the critical feature dimensions for advanced semiconductor devices have decreased to 20 nm and below. Critical scaling limitations are increasingly driving the transition to 3D solutions such as multi-gate MOSFETs and 3D NAND structures. These structures create significant challenges for dielectric and conductor etching, especially given the high aspect ratio (HAR) of the features. Plasma etching equipment must therefore be capable of exacting profile control across the entire wafer for feature aspect ratios up to 80:1, high throughput, and exceptionally high selectivity. The multiple challenges for advanced 3D structures are addressed by Applied Material's plasma etching chambers by providing highly sophisticated control of ion energy, wafer temperature and plasma chemistry. Given the costs associated with such complex designs and reduced development time-scales, much of these design innovations have been enabled by utilizing advanced computational plasma modeling tools. We have expended considerable effort to develop 3-dimensional coupled plasma and electromagnetic modeling tools in recent years. In this work, we report on these modeling software and their application to plasma processing system design and evaluation of strategies for hardware and process improvement. Several of these examples deal with process uniformity, which is one of the major challenges facing plasma processing equipment design on large substrates. Three-dimensional plasma modeling is used to understand the sources of plasma non-uniformity, including the radio-frequency (RF) current path, and develop uniformity improvement techniques. Examples from coupled equipment and process models to investigate the dynamics of pulsed plasmas and their impact on plasma chemistry will

  4. Plasma Spraying of Ceramics with Particular Difficulties in Processing

    NASA Astrophysics Data System (ADS)

    Mauer, G.; Schlegel, N.; Guignard, A.; Jarligo, M. O.; Rezanka, S.; Hospach, A.; Vaßen, R.

    2015-01-01

    Emerging new applications and growing demands of plasma-sprayed coatings initiate the development of new materials. Regarding ceramics, often complex compositions are employed to achieve advanced material properties, e.g., high thermal stability, low thermal conductivity, high electronic and ionic conductivity as well as specific thermo-mechanical properties and microstructures. Such materials however, often involve particular difficulties in processing by plasma spraying. The inhomogeneous dissociation and evaporation behavior of individual constituents can lead to changes of the chemical composition and the formation of secondary phases in the deposited coatings. Hence, undesired effects on the coating characteristics are encountered. In this work, examples of such challenging materials are investigated, namely pyrochlores applied for thermal barrier coatings as well as perovskites for gas separation membranes. In particular, new plasma spray processes like suspension plasma spraying and plasma spray-physical vapor deposition are considered. In some cases, plasma diagnostics are applied to analyze the processing conditions.

  5. Plasma Spraying of Ceramics with Particular Difficulties in Processing

    NASA Astrophysics Data System (ADS)

    Mauer, G.; Schlegel, N.; Guignard, A.; Jarligo, M. O.; Rezanka, S.; Hospach, A.; Vaßen, R.

    2014-09-01

    Emerging new applications and growing demands of plasma-sprayed coatings initiate the development of new materials. Regarding ceramics, often complex compositions are employed to achieve advanced material properties, e.g., high thermal stability, low thermal conductivity, high electronic and ionic conductivity as well as specific thermo-mechanical properties and microstructures. Such materials however, often involve particular difficulties in processing by plasma spraying. The inhomogeneous dissociation and evaporation behavior of individual constituents can lead to changes of the chemical composition and the formation of secondary phases in the deposited coatings. Hence, undesired effects on the coating characteristics are encountered. In this work, examples of such challenging materials are investigated, namely pyrochlores applied for thermal barrier coatings as well as perovskites for gas separation membranes. In particular, new plasma spray processes like suspension plasma spraying and plasma spray-physical vapor deposition are considered. In some cases, plasma diagnostics are applied to analyze the processing conditions.

  6. Dry plasma processing for industrial crystalline silicon solar cell production

    NASA Astrophysics Data System (ADS)

    Hofmann, M.; Rentsch, J.; Preu, R.

    2010-10-01

    This paper gives an overview on the standard crystalline silicon solar cell manufacturing processes typically applied in industry. Main focus has been put on plasma processes which can replace existing, mainly wet chemical processes within the standard process flow. Finally, additional plasma processes are presented which are suited for higher-efficient solar cells, i.e. for the “passivated emitter and rear cell” concept (PERC) or the “heterojunction with intrinsic thin layer” approach (HIT). Plasma processes for the deposition of thin dielectric or semiconducting layers for surface passivation, emitter deposition or anti-reflective coating purposes are presented. Plasma etching processes for the removal of phosphorus silicate glass or parasitic emitters, for wafer cleaning and masked and mask-free surface texturisation are discussed.

  7. Development of finite element analysis method for three-dimensional hot bending and direct quench (3DQ) process

    NASA Astrophysics Data System (ADS)

    Kubota, Hiroaki; Tomizawa, Atsushi; Yamamoto, Kenji; Okada, Nobuhiro

    2013-05-01

    The automotive industry has been focusing on developing lighter vehicles to improve fuel economy and crash safety. In order to meet these requirements, Three Dimensional Hot Bending and Direct Quench (3DQ) Technology has been developed, which enables a manufacturer to form hollow tubular automotive parts with a tensile strength of 1,470 MPa or over. 3DQ is a type of consecutive forming that allows bending and quenching at the same time, with a tube feeding device, an induction heater, a cooling device, and a bending device. In this research, a coupled thermomechanical-metallurgical finite element analysis (FEA) method has been developed to investigate the deformation behavior and to predict the forming capability of 3DQ. In the developed FEA procedure, the temperature distribution was calculated with electro magnetic and heat transfer analysis, and the flow stress was defined by transformation models and linear mixture rule. An experimental formula was used to track the ferrite-austenite transformation, and a Koistinen-Marburger relationship was employed to describe austenite-martensite change. The simulated results were compared with the experimental measurements, and the effectiveness of the developed FEA method was confirmed. Furthermore, the deformation characteristics of 3DQ, such as the wrinkling limit and the thickness change, were investigated, and simple equations to describe them were proposed.

  8. Fast quench reactor and method

    DOEpatents

    Detering, Brent A.; Donaldson, Alan D.; Fincke, James R.; Kong, Peter C.

    2002-01-01

    A fast quench reaction includes a reactor chamber having a high temperature heating means such as a plasma torch at its inlet and a restrictive convergent-divergent nozzle at its outlet end. Reactants are injected into the reactor chamber. The resulting heated gaseous stream is then rapidly cooled by passage through the nozzle. This "freezes" the desired end product(s) in the heated equilibrium reaction stage.

  9. Fast quench reactor and method

    DOEpatents

    Detering, Brent A.; Donaldson, Alan D.; Fincke, James R.; Kong, Peter C.

    2002-09-24

    A fast quench reaction includes a reactor chamber having a high temperature heating means such as a plasma torch at its inlet and a restrictive convergent-divergent nozzle at its outlet end. Reactants are injected into the reactor chamber. The resulting heated gaseous stream is then rapidly cooled by passage through the nozzle. This "freezes" the desired end product(s) in the heated equilibrium reaction stage.

  10. Fast quench reactor and method

    DOEpatents

    Detering, Brent A.; Donaldson, Alan D.; Fincke, James R.; Kong, Peter C.

    1998-01-01

    A fast quench reaction includes a reactor chamber having a high temperature heating means such as a plasma torch at its inlet and a restrictive convergent-divergent nozzle at its outlet end. Reactants are injected into the reactor chamber. The resulting heated gaseous stream is then rapidly cooled by passage through the nozzle. This "freezes" the desired end product(s) in the heated equilibrium reaction stage.

  11. Fast quench reactor and method

    DOEpatents

    Detering, B.A.; Donaldson, A.D.; Fincke, J.R.; Kong, P.C.

    1998-05-12

    A fast quench reactor includes a reactor chamber having a high temperature heating means such as a plasma torch at its inlet and a restrictive convergent-divergent nozzle at its outlet end. Reactants are injected into the reactor chamber. The resulting heated gaseous stream is then rapidly cooled by passage through the nozzle. This ``freezes`` the desired end product(s) in the heated equilibrium reaction stage. 7 figs.

  12. Nanosecond transient processes in the triethylamine quenching of benzophenone triplets in aqueous alkaline media. Substituent effect, ketyl radical deprotonation, and secondary photoreduction kinetics

    SciTech Connect

    Bhattacharyya, K.; Das, P.K.

    1986-08-14

    In the course of benzophenone triplet quenching by triethylamine (TEA) at high concentrations in alkaline aqueous acetonitrile, two temporally distinct processes are observed for ketyl radical anion formation. The fast component occurs on a nanosecond time scale, has kinetics sensitive to basicity and water content of the medium, and is ascribed to the deprotonation of the diphenylhydroxymethyl radical initially produced as a result of subnanosecond intra-ion-pair proton transfer. The slow process occurs on a microsecond time scale and is characterized by pseudo-first-order rate constants linearly dependent on ketone ground-state concentration; this is assigned to the one-electron reduction of the ketone by the methyl(diethylamino)methyl radical (derived from TEA). Substituent effects on the kinetics of the two processes follow trends expected from those of the acidity of diarylhydroxymethyl radicals and of the behavior of diaryl ketones as oxidants. Neither of the two processes is observed with N,N-dimethylaniline (DMA) and 1,4-diazabicyclo(2.2.2)octane (DABCO) as quenchers. The electron or hydrogen transfer yields in the course of diaryl ketone triplet quenching by the three amines are all close to unity, suggesting that the back electron transfer in the triplet ion pairs is relatively unimportant.

  13. Quenching star formation in cluster galaxies

    NASA Astrophysics Data System (ADS)

    Taranu, Dan S.; Hudson, Michael J.; Balogh, Michael L.; Smith, Russell J.; Power, Chris; Oman, Kyle A.; Krane, Brad

    2014-05-01

    In order to understand the processes that quench star formation in cluster galaxies, we construct a library of subhalo orbits drawn from Λ cold dark matter cosmological N-body simulations of four rich clusters. We combine these orbits with models of star formation followed by environmental quenching, comparing model predictions with observed bulge and disc colours and stellar absorption line-strength indices of luminous cluster galaxies. Models in which the bulge stellar populations depend only on the galaxy subhalo mass while the disc is quenched upon infall are acceptable fits to the data. An exponential disc quenching time-scale of 3-3.5 Gyr is preferred. Quenching in lower mass groups prior to infall (`pre-processing') provides better fits, with similar quenching time-scales. Models with short (≲1 Gyr) quenching time-scales yield excessively steep cluster-centric gradients in disc colours and Balmer line indices, even if quenching is delayed for several Gyr. The data slightly prefer models where quenching occurs only for galaxies falling within ˜0.5r200. These results imply that the environments of rich clusters must impact star formation rates of infalling galaxies on relatively long time-scales, indicative of gentler quenching mechanisms such as slow `strangulation' over more rapid ram-pressure stripping.

  14. The processing of nanopowders by thermal plasma technology

    NASA Astrophysics Data System (ADS)

    Tong, Lirong; Reddy, Ramana G.

    2006-04-01

    The thermal plasma synthesis of nanopowders is a relatively new technology with great potential for future industrial applications. This article introduces research carried out in the plasma processing laboratory at the University of Alabama in Tuscaloosa, Alabama. Ceramic nanopowders and nanofibers (SiC, TiC, and B4C) and nanocomposite powders (TiC-Al(Ti), TiC-Fe(Ti), and TiN-Fe (Ti)) were successfully synthesized by thermal plasma technology.

  15. Quench propagation velocity for highly stabilized conductors

    SciTech Connect

    Mints, R.G. |; Ogitsu, T. |; Devred, A.

    1995-05-01

    Quench propagation velocity in conductors having a large amount of stabilizer outside the multifilamentary area is considered. It is shown that the current redistribution process between the multifilamentary area and the stabilizer can strongly effect the quench propagation. A criterion is derived determining the conditions under which the current redistribution process becomes significant, and a model of effective stabilizer area is suggested to describe its influence on the quench propagation velocity. As an illustration, the model is applied to calculate the adiabatic quench propagation velocity for a conductor geometry with a multifilamentary area embedded inside the stabilizer.

  16. HIP quench technology

    SciTech Connect

    Bergman, C.; Westerlund, J.; Zimmerman, F.X.

    1996-12-31

    Hot Isostatic Pressing (HIP) is a viable production process today for densifying metals, ceramics, and composites to achieve fully dense parts. One major drawback for conventional HIPing is the long ten to twelve hour cycle time resulting in low productivity and high processing cost. Drastic furnace improvements have been made in the late 1980`s with the advent of Uniform Rapid Cooling (URC) called HIP Quenching. This innovation allows floor/floor cycles as short as four to five hours with one hour soak depending on the material to be HIPed. A flow device such as a fan is utilized at the base of the furnace for forced gas convection in promoting main features to: (1) accelerate time for heating, soaking and cooling; (2) add combined solution heat treating; and (3) reduce thermal distortion of parts with varying cross-sections. All three points promise to positively effect better economy with improved property and quality to promote the HIP process further. This paper describes the URC technology and illustrates a couple of HIP Quench studies made for a turbine disc and efficient High Speed Steel powder consolidation.

  17. Design of a High-Throughput Plasma-Processing System

    SciTech Connect

    Darkazalli, Ghazi; Matthei, Keith; Ruby, Douglas S.

    1999-07-20

    Sandia National Laboratories has demonstrated significant performance gains in crystalline silicon solar cell technology through the use of plasma-processing for the deposition of silicon nitride by Plasma Enhanced Chemical Vapor Deposition (PECVD), plasma-hydrogenation of the nitride layer, and reactive-ion etching of the silicon surface prior to the deposition to decrease the reflectivity of the surface. One of the major problems of implementing plasma processing into a cell production line is the batch configuration and/or low throughput of the systems currently available. This report describes the concept of a new in-line plasma processing system that could meet the industrial requirements for a high-throughput and cost effective solution for mass production of solar cells.

  18. Plasma processing methods for hydrogen production

    NASA Astrophysics Data System (ADS)

    Mizeraczyk, Jerzy; Jasiński, Mariusz

    2016-08-01

    In the future a transfer from the fossil fuel-based economy to hydrogen-based economy is expected. Therefore the development of systems for efficient H2 production becomes important. The several conventional methods of mass-scale (or central) H2 production (methane, natural gas and higher hydrocarbons reforming, coal gasification reforming) are well developed and their costs of H2 production are acceptable. However, due to the H2 transport and storage problems the small-scale (distributed) technologies for H2 production are demanded. However, these new technologies have to meet the requirement of producing H2 at a production cost of (1-2)/kg(H2) (or 60 g(H2)/kWh) by 2020 (the U.S. Department of Energy's target). Recently several plasma methods have been proposed for the small-scale H2 production. The most promising plasmas for this purpose seems to be those generated by gliding, plasmatron and nozzle arcs, and microwave discharges. In this paper plasma methods proposed for H2 production are briefly described and critically evaluated from the view point of H2 production efficiency. The paper is aiming at answering a question if any plasma method for the small-scale H2 production approaches such challenges as the production energy yield of 60 g(H2)/kWh, high production rate, high reliability and low investment cost. Contribution to the topical issue "6th Central European Symposium on Plasma Chemistry (CESPC-6)", edited by Nicolas Gherardi, Ester Marotta and Cristina Paradisi

  19. Status and potential of atmospheric plasma processing of materials

    SciTech Connect

    Pappas, Daphne

    2011-03-15

    This paper is a review of the current status and potential of atmospheric plasma technology for materials processing. The main focus is the recent developments in the area of dielectric barrier discharges with emphasis in the functionalization of polymers, deposition of organic and inorganic coatings, and plasma processing of biomaterials. A brief overview of both the equipment being used and the physicochemical reactions occurring in the gas phase is also presented. Atmospheric plasma technology offers major industrial, economic, and environmental advantages over other conventional processing methods. At the same time there is also tremendous potential for future research and applications involving both the industrial and academic world.

  20. Collisional and Radiative Processes in Optically Thin Plasmas

    NASA Astrophysics Data System (ADS)

    Bradshaw, Stephen J.; Raymond, John

    2013-10-01

    Most of our knowledge of the physical processes in distant plasmas is obtained through measurement of the radiation they produce. Here we provide an overview of the main collisional and radiative processes and examples of diagnostics relevant to the microphysical processes in the plasma. Many analyses assume a time-steady plasma with ion populations in equilibrium with the local temperature and Maxwellian distributions of particle velocities, but these assumptions are easily violated in many cases. We consider these departures from equilibrium and possible diagnostics in detail.

  1. Collisional and Radiative Processes in Optically Thin Plasmas

    NASA Astrophysics Data System (ADS)

    Bradshaw, Stephen J.; Raymond, John

    Most of our knowledge of the physical processes in distant plasmas is obtained through measurement of the radiation they produce. Here we provide an overview of the main collisional and radiative processes and examples of diagnostics relevant to the microphysical processes in the plasma. Many analyses assume a time-steady plasma with ion populations in equilibrium with the local temperature and Maxwellian distributions of particle velocities, but these assumptions are easily violated in many cases. We consider these departures from equilibrium and possible diagnostics in detail.

  2. Formation of a metastable ferromagnetic tau phase during containerless melt processing and rapid quenching in Mn-Al-C alloys

    NASA Technical Reports Server (NTRS)

    Kim, Y. J.; Perepezko, J. H.

    1992-01-01

    Solidification of selected Mn-Al-C alloys during containerless levitation and rapid quenching has yielded the first report for a ferromagnetic metastable tau phase formed directly from the melt. Complete solidification to tau phase was interrupted by the competitive evolution of an equilibrium epsilon phase during recalescence. The amount of undercooling required to produce the metastable ferromagnetic tau phase in a Mn(0.55)Al(0.433)C(0.017) alloy during solidification was estimated as approximately 470 K based on differential thermal analysis results. When the alloy carbon content was increased to 3.4 at. pct, transition in structure development occurred so that the samples exhibited gamma 2 phase formation as well as tau and epsilon phases.

  3. Analytical and experimental studies for thermal plasma processing of materials

    NASA Astrophysics Data System (ADS)

    Work continued on thermal plasma processing of materials. This quarter, ceramic powders of carbides, aluminum nitride, oxides, solids solutions, magnetic and non magnetic spinels, superconductors, and composites have been successfully synthesized in a Triple DC Torch Plasma Jet Reactor (TTPR) and in a single DC Plasma Jet Reactor. All the ceramic powders with the exception of AIN were synthesized using a novel injection method developed to overcome the problems associated with solid injection, in particular for the single DC plasma jet reactor, and to realize the benefits of gas phase reactions. Also, initial experiments have been performed for the deposition of diamond coatings on Si wafers using the TTPR with methane as the carbon source. Well faceted diamond crystallites were deposited on the surface of the wafers, forming a continuous one particle thick coating. For measuring temperature and velocity fields in plasma systems, enthalpy probes have been developed and tested. The validity has been checked by performing energy and mass flux balances in an argon plasma jet operated in argon atmosphere. Total Gibbs free energy minimization calculations using a quasi-equilibrium modification have been applied to simulate several chemical reactions. Plasma reactor modelling has been performed for the counter-flow liquid injection plasma synthesis experiment. Plasma diagnostics has been initiated to determine the pressure gradient in the coalesced part of the plasma jet. The pressure gradient drives the diffusion of chemical species which ultimately controls the chemical reactions.

  4. Analysis of benzoquinone decomposition in solution plasma process

    NASA Astrophysics Data System (ADS)

    Bratescu, M. A.; Saito, N.

    2016-01-01

    The decomposition of p-benzoquinone (p-BQ) in Solution Plasma Processing (SPP) was analyzed by Coherent Anti-Stokes Raman Spectroscopy (CARS) by monitoring the change of the anti-Stokes signal intensity of the vibrational transitions of the molecule, during and after SPP. Just in the beginning of the SPP treatment, the CARS signal intensities of the ring vibrational molecular transitions increased under the influence of the electric field of plasma. The results show that plasma influences the p-BQ molecules in two ways: (i) plasma produces a polarization and an orientation of the molecules in the local electric field of plasma and (ii) the gas phase plasma supplies, in the liquid phase, hydrogen and hydroxyl radicals, which reduce or oxidize the molecules, respectively, generating different carboxylic acids. The decomposition of p-BQ after SPP was confirmed by UV-visible absorption spectroscopy and liquid chromatography.

  5. Method and system for nanoscale plasma processing of objects

    DOEpatents

    Oehrlein, Gottlieb S.; Hua, Xuefeng; Stolz, Christian

    2008-12-30

    A plasma processing system includes a source of plasma, a substrate and a shutter positioned in close proximity to the substrate. The substrate/shutter relative disposition is changed for precise control of substrate/plasma interaction. This way, the substrate interacts only with a fully established, stable plasma for short times required for nanoscale processing of materials. The shutter includes an opening of a predetermined width, and preferably is patterned to form an array of slits with dimensions that are smaller than the Debye screening length. This enables control of the substrate/plasma interaction time while avoiding the ion bombardment of the substrate in an undesirable fashion. The relative disposition between the shutter and the substrate can be made either by moving the shutter or by moving the substrate.

  6. Simulations of auroral plasma processes - Electric fields, waves and particles

    NASA Technical Reports Server (NTRS)

    Singh, Nagendra; Thiemann, H.; Schunk, R. W.

    1987-01-01

    Plasma processes driven by current sheets of finite thicknesses in an ambient magnetized plasma are studied using a 2 1/2 dimensional particle-in-cell code, and similarities are found between simulated plasma processes and those observed in the auroral plasma. Current sheets are shown to be bounded by large perpendicular electric fields occurring near their edges above the conducting boundary. Shaped potential structures form when the current sheets are narrow, and when the current sheets are wide, potential structures develop a significant parallel potential drop such that the electrons are accelerated upwards. Downward parallel electric fields of variable strength are noted in the downward current region, and double layer formation is seen in both narrow and wide current sheets. High frequency oscillations near the electron plasma frequency and its harmonic are seen, and low frequency waves are observed.

  7. Holographic Jet Quenching

    NASA Astrophysics Data System (ADS)

    Ficnar, Andrej

    In this dissertation we study the phenomenon of jet quenching in quark-gluon plasma using the AdS/CFT correspondence. We start with a weakly coupled, perturbative QCD approach to energy loss, and present a Monte Carlo code for computation of the DGLV radiative energy loss of quarks and gluons at an arbitrary order in opacity. We use the code to compute the radiated gluon distribution up to n=9 order in opacity, and compare it to the thin plasma (n=1) and the multiple soft scattering (n=infinity) approximations. We furthermore show that the gluon distribution at finite opacity depends in detail on the screening mass mu and the mean free path lambda. In the next part, we turn to the studies of how heavy quarks, represented as "trailing strings" in AdS/CFT, lose energy in a strongly coupled plasma. We study how the heavy quark energy loss gets modified in a "bottom-up" non-conformal holographic model, constructed to reproduce some properties of QCD at finite temperature and constrained by fitting the lattice gauge theory results. The energy loss of heavy quarks is found to be strongly sensitive to the medium properties. We use this model to compute the nuclear modification factor RAA of charm and bottom quarks in an expanding plasma with Glauber initial conditions, and comment on the range of validity of the model. The central part of this thesis is the energy loss of light quarks in a strongly coupled plasma. Using the standard model of "falling strings", we present an analytic derivation of the stopping distance of light quarks, previously available only through numerical simulations, and also apply it to the case of Gauss-Bonnet higher derivative gravity. We then present a general formula for computing the instantaneous energy loss in non-stationary string configurations. Application of this formula to the case of falling strings reveals interesting phenomenology, including a modified Bragg-like peak at late times and an approximately linear path dependence. Based

  8. Time dependent atomic processes in discharge produced low Z plasma

    NASA Astrophysics Data System (ADS)

    Yuyama, M.; Sasaki, T.; Horioka, K.; Kawamura, T.

    2008-05-01

    The z-pinch simulation have been performed with magneto-hydro dynamics and atomic population kinetics codes. A factor associated with transient atomic processes was proposed. The atomic transient degrees of dopant lithium in hydrogen plasma were calculated with initial plasma densities of 1.0 × 1016 ~ 5.0 × 1017cm-3. The higher initial plasma density is, the lower is the transient degree generally. It is also found that the transient properties of the atomic processes are sensitive to ionization energy and electron temperature.

  9. Method of processing materials using an inductively coupled plasma

    DOEpatents

    Hull, D.E.; Bieniewski, T.M.

    1987-04-13

    A method of processing materials. The invention enables ultrafine, ultrapure powders to be formed from solid ingots in a gas free environment. A plasma is formed directly from an ingot which insures purity. The vaporized material is expanded through a nozzle and the resultant powder settles on a cold surface. An inductively coupled plasma may also be used to process waste chemicals. Noxious chemicals are directed through a series of plasma tubes, breaking molecular bonds and resulting in relatively harmless atomic constituents. 3 figs.

  10. Fe{sub 2}O{sub 3} nanopowders prepared by a thermal plasma process for water oxidation

    SciTech Connect

    Lee, Dongeun; Choi, Yong-Wook; Na, Ye-Seul; Choi, Soo-Suk; Park, Dong-Wha; Choi, Jinsub

    2015-08-15

    Highlights: • Hematite nanopowders with a high purity were synthesized by a DC thermal plasma process. • Fe{sub 3}O{sub 4} is formed during the formation of Fe{sub 2}O{sub 3} by thermal plasma with iron and oxygen sources. • Hematite nanopowders with a high purity show higher PEC performance compared to mixed oxides. - Abstract: Hematite (Fe{sub 2}O{sub 3}) nanopowders were synthesized from commercially available micro-sized iron powders by a DC thermal plasma process at atmospheric pressure. The micro-sized iron powders were vaporized in the plasma region, after which the plasma processing equipment was rapidly quenched, resulting in the formation of iron nanopowders with a size of less than 100 nm. Subsequently, the iron nanopowders were heated to convert hematite with a high purity, which was then formed into a thin film with a binder for preparation of electrodes for photoelectrochemical water oxidation. Iron oxide nanopowders were characterized by scanning electron microscopy (SEM), X-ray diffraction (XRD), particle size analysis (PSA) and transmission electron microscopy (TEM). The photoelectrochemical properties of the Fe{sub 2}O{sub 3} film were characterized in 1 M NaOH under AM 1.5 conditions.

  11. Plasma Sheet Source and Loss Processes

    NASA Technical Reports Server (NTRS)

    Lennartsson, O. W.

    2000-01-01

    Data from the TIMAS ion mass spectrometer on the Polar satellite, covering 15 ev/e to 33 keV/e in energy and essentially 4(pi) in view angles, are used to investigate the properties of earthward (sunward) field-aligned flows of ions, especially protons, in the plasma sheet-lobe transition region near local midnight. A total of 142 crossings of this region are analyzed at 12-sec time resolution, all in the northern hemisphere, at R(SM) approx. 4 - 7 R(sub E), and most (106) in the poleward (sunward) direction. Earthward proton flows are prominent in this transition region (greater than 50% of the time), typically appearing as sudden "blasts" with the most energetic protons (approx. 33 keV) arriving first with weak flux, followed by protons of decreasing energy and increasing flux until either: (1) a new "blast" appears, (2) the flux ends at a sharp boundary, or (3) the flux fades away within a few minutes as the mean energy drops to a few keV. Frequent step-like changes (less than 12 sec) of the flux suggest that perpendicular gradients on the scale of proton gyroradii are common. Peak flux is similar to central plasma sheet proton flux (10(exp 5) - 10(exp 6)/[cq cm sr sec keV/e] and usually occurs at E approx. 4 - 12 keV. Only the initial phase of each "blast" (approx. 1 min) displays pronounced field-alignment of the proton velocity distribution, consistent with the time-of-flight separation of a more or less isotropic source distribution with df/d(nu) less than 0. The dispersive signatures are often consistent with a source at R(SM) less than or equal to 30 R(sub E). No systematic latitudinal velocity dispersion is found, implying that the equatorial plasma source is itself convecting. In short, the proton "blasts" appear as sudden local expansions of central plasma sheet particles along reconfigured ("dipolarized") magnetic field lines.

  12. Real-Time Fault Classification for Plasma Processes

    PubMed Central

    Yang, Ryan; Chen, Rongshun

    2011-01-01

    Plasma process tools, which usually cost several millions of US dollars, are often used in the semiconductor fabrication etching process. If the plasma process is halted due to some process fault, the productivity will be reduced and the cost will increase. In order to maximize the product/wafer yield and tool productivity, a timely and effective fault process detection is required in a plasma reactor. The classification of fault events can help the users to quickly identify fault processes, and thus can save downtime of the plasma tool. In this work, optical emission spectroscopy (OES) is employed as the metrology sensor for in-situ process monitoring. Splitting into twelve different match rates by spectrum bands, the matching rate indicator in our previous work (Yang, R.; Chen, R.S. Sensors 2010, 10, 5703–5723) is used to detect the fault process. Based on the match data, a real-time classification of plasma faults is achieved by a novel method, developed in this study. Experiments were conducted to validate the novel fault classification. From the experimental results, we may conclude that the proposed method is feasible inasmuch that the overall accuracy rate of the classification for fault event shifts is 27 out of 28 or about 96.4% in success. PMID:22164001

  13. Real-time fault classification for plasma processes.

    PubMed

    Yang, Ryan; Chen, Rongshun

    2011-01-01

    Plasma process tools, which usually cost several millions of US dollars, are often used in the semiconductor fabrication etching process. If the plasma process is halted due to some process fault, the productivity will be reduced and the cost will increase. In order to maximize the product/wafer yield and tool productivity, a timely and effective fault process detection is required in a plasma reactor. The classification of fault events can help the users to quickly identify fault processes, and thus can save downtime of the plasma tool. In this work, optical emission spectroscopy (OES) is employed as the metrology sensor for in-situ process monitoring. Splitting into twelve different match rates by spectrum bands, the matching rate indicator in our previous work (Yang, R.; Chen, R.S. Sensors 2010, 10, 5703-5723) is used to detect the fault process. Based on the match data, a real-time classification of plasma faults is achieved by a novel method, developed in this study. Experiments were conducted to validate the novel fault classification. From the experimental results, we may conclude that the proposed method is feasible inasmuch that the overall accuracy rate of the classification for fault event shifts is 27 out of 28 or about 96.4% in success.

  14. Effect of supply voltage and body-biasing on single-event transient pulse quenching in bulk fin field-effect-transistor process

    NASA Astrophysics Data System (ADS)

    Jun-Ting, Yu; Shu-Ming, Chen; Jian-Jun, Chen; Peng-Cheng, Huang; Rui-Qiang, Song

    2016-04-01

    Charge sharing is becoming an important topic as the feature size scales down in fin field-effect-transistor (FinFET) technology. However, the studies of charge sharing induced single-event transient (SET) pulse quenching with bulk FinFET are reported seldomly. Using three-dimensional technology computer aided design (3DTCAD) mixed-mode simulations, the effects of supply voltage and body-biasing on SET pulse quenching are investigated for the first time in bulk FinFET process. Research results indicate that due to an enhanced charge sharing effect, the propagating SET pulse width decreases with reducing supply voltage. Moreover, compared with reverse body-biasing (RBB), the circuit with forward body-biasing (FBB) is vulnerable to charge sharing and can effectively mitigate the propagating SET pulse width up to 53% at least. This can provide guidance for radiation-hardened bulk FinFET technology especially in low power and high performance applications. Project supported by the National Natural Science Foundation of China (Grant Nos. 61376109, 61434007, and 61176030).

  15. Investigation of plasma induced electrical and chemical factors and their contribution processes to plasma gene transfection.

    PubMed

    Jinno, Masafumi; Ikeda, Yoshihisa; Motomura, Hideki; Kido, Yugo; Satoh, Susumu

    2016-09-01

    This study has been done to know what kind of factors in plasmas and processes on cells induce plasma gene transfection. We evaluated the contribution weight of three groups of the effects and processes, i.e. electrical, chemical and biochemical ones, inducing gene transfection. First, the laser produced plasma (LPP) was employed to estimate the contribution of the chemical factors. Second, liposomes were fabricated and employed to evaluate the effects of plasma irradiation on membrane under the condition without biochemical reaction. Third, the clathrin-dependent endocytosis, one of the biochemical processes was suppressed. It becomes clear that chemical factors (radicals and reactive oxygen/nitrogen species) do not work by itself alone and electrical factors (electrical current, charge and field) are essential to plasma gene transfection. It turned out the clathrin-dependent endocytosis is the process of the transfection against the 60% in all the transfected cells. The endocytosis and electrical poration are dominant in plasma gene transfection, and neither permeation through ion channels nor chemical poration is dominant processes. The simultaneous achievement of high transfection efficiency and high cell survivability is attributed to the optimization of the contribution weight among three groups of processes by controlling the weight of electrical and chemical factors. PMID:27136710

  16. Linear and Nonlinear MHD Wave Processes in Plasmas. Final Report

    SciTech Connect

    Tataronis, J. A.

    2004-06-01

    This program treats theoretically low frequency linear and nonlinear wave processes in magnetized plasmas. A primary objective has been to evaluate the effectiveness of MHD waves to heat plasma and drive current in toroidal configurations. The research covers the following topics: (1) the existence and properties of the MHD continua in plasma equilibria without spatial symmetry; (2) low frequency nonresonant current drive and nonlinear Alfven wave effects; and (3) nonlinear electron acceleration by rf and random plasma waves. Results have contributed to the fundamental knowledge base of MHD activity in symmetric and asymmetric toroidal plasmas. Among the accomplishments of this research effort, the following are highlighted: Identification of the MHD continuum mode singularities in toroidal geometry. Derivation of a third order ordinary differential equation that governs nonlinear current drive in the singular layers of the Alfvkn continuum modes in axisymmetric toroidal geometry. Bounded solutions of this ODE implies a net average current parallel to the toroidal equilibrium magnetic field. Discovery of a new unstable continuum of the linearized MHD equation in axially periodic circular plasma cylinders with shear and incompressibility. This continuum, which we named “accumulation continuum” and which is related to ballooning modes, arises as discrete unstable eigenfrequency accumulate on the imaginary frequency axis in the limit of large mode numbers. Development of techniques to control nonlinear electron acceleration through the action of multiple coherent and random plasmas waves. Two important elements of this program aye student participation and student training in plasma theory.

  17. On the impact of the temporal variability of the collisional quenching process on the mesospheric OH emission layer: a study based on SD-WACCM4 and SABER

    NASA Astrophysics Data System (ADS)

    Kowalewski, S.; von Savigny, C.; Palm, M.; McDade, I. C.; Notholt, J.

    2014-09-01

    The mesospheric OH Meinel emissions are subject of many theoretical and observational studies devoted to this part of the atmosphere. Depending on the initial vibrational level of excitation the altitude of the considered OH Meinel emission is systematically shifted, which has important implications for the intercomparison of different studies considering different transition bands. Previous model studies suggest that these vertical shifts are essentially caused by the process of collisional quenching with atomic oxygen. Following this hypothesis, a recent study found experimental evidence of a coherent seasonality at tropical latitudes between vertical shifts of different OH Meinel bands and changes in atomic oxygen concentrations. Despite the consistent finding of the above mentioned hypothesis, it cannot be excluded that the actual temporal variability of the vertical shifts between different OH Meinel bands may in addition be controlled or even dominated by other processes. It remains an open question whether the observed temporal evolution is indeed mainly controlled by the modulation of the collisional quenching process with atomic oxygen. By means of a sensitivity study which employs a quenching model to simulations made with the SD-WACCM4 chemistry climate model, we aim at assessing this question. From this study we find that the observed seasonality of vertical OH Meinel shifts is only partially controlled by temporal changes in atomic oxygen concentrations, while molecular oxygen has another noticeable impact on the vertical OH Meinel shifts. This in particular becomes evident for the diurnal variability of vertical OH Meinel shifts, which reveal only a poor correlation with the atomic oxygen species. Furthermore, changes in the H + O3 source gases provide another mechanism that can potentially affect the diurnal variability in addition. By comparison with limb radiance observations from the SABER/TIMED satellite this provides an explanation for the less

  18. Electron-driven processes in high-pressure plasmas

    NASA Astrophysics Data System (ADS)

    Becker, K. H.; Masoud, N. M.; Martus, K. E.; Schoenbach, K. H.

    2005-08-01

    This review article summarizes results from selected recent studies of collisional and radiative processes initiated and driven by low-energy electron interactions with atoms and molecules in high-pressure plasmas. A special emphasis of the article is on spectroscopic studies of plasmas used as sources for non-coherent vacuum ultraviolet radiation such as rare excimer emissions and atomic and molecular emissions from plasmas in admixtures of rare gases and the molecular gases H{2} and N{2}. An attempt is made to correlate the various observed emission features and their dependence on the plasma operating parameters (pressure, power, gas mixture, mode of excitation, etc.) to the underlying microscopic atomic and molecular processes.

  19. The research of anodic microdischarges in plasma-electrolyte processing

    NASA Astrophysics Data System (ADS)

    Kashapov, L. N.; Kashapov, N. F.; Kashapov, R. N.

    2015-06-01

    The article is devoted to the topic of anodic microdischarges in plasma-electrolyte processing. The aim of this work is to research the conditions of anodic micro-discharges during the plasma-electrolytic treatment and the influence they have on the surface of metals. As a result of experimental researches, was made a mechanism of influence anodic microdischarges on the surface of the electrode, burning of anodic microdischarges occur in the voltage range of 40-100 W.

  20. Single photon detection with self-quenching multiplication

    NASA Technical Reports Server (NTRS)

    Zheng, Xinyu (Inventor); Cunningham, Thomas J. (Inventor); Pain, Bedabrata (Inventor)

    2011-01-01

    A photoelectronic device and an avalanche self-quenching process for a photoelectronic device are described. The photoelectronic device comprises a nanoscale semiconductor multiplication region and a nanoscale doped semiconductor quenching structure including a depletion region and an undepletion region. The photoelectronic device can act as a single photon detector or a single carrier multiplier. The avalanche self-quenching process allows electrical field reduction in the multiplication region by movement of the multiplication carriers, thus quenching the avalanche.

  1. Kinetic processes in the plasma sheet observed during auroral activity

    NASA Astrophysics Data System (ADS)

    Fillingim, Matthew Owen

    In this dissertation we analyze plasma sheet magnetic field and plasma data observed during varying levels of auroral activity from very small, isolated events known as pseudobreakups to large, global events known as substorms. The plasma and magnetic field data are taken from instruments onboard the WIND spacecraft while it traverses the near-Earth plasma sheet. Simultaneous global auroral images from POLAR/UVI allow us to determine the auroral activity level. The goal of this dissertation is to provide the most complete set of plasma sheet observations during auroral activity currently available. The kinetic aspects of the plasma dynamics which have largely been ingnored in other works are emphasized here. We have the capability to resolve changes in the three dimensional ion distribution functions with a time resolution comparable to or faster than the local ion gyroperiod. In addition, we consider the typically neglected electron dynamics when relating plasma sheet processes to the aurora. We find that the plasma sheet signatures of both pseudobreakups and substorms appear very similar. During both types of events, increases in auroral precipitation into the ionosphere are associated with large amplitude, high frequency magnetic field fluctuations, large Earthward ion < v>, increases in the fluxes of high energy ions and electrons, and hardening of the electron spectrum. Both ion and electron distributions appear to be composed of multiple components. Electromagnetic waves with power at frequencies up to and above the local proton gyrofrequency area also observed. Additionally, the ion distributions can change significantly in one gyroperiod. Together, these results imply that the microphysical processes occurring in the plasma sheet during pseudobreakups and substorms are the same and that kinetic effects are important. Therefore, magnetohydrodynamics (MHD) cannot adequately describe the physics occurring during large ion < v> events.

  2. Non-linear effects of initial melt temperatures on microstructures and mechanical properties during quenching process of liquid Cu46Zr54 alloy

    NASA Astrophysics Data System (ADS)

    Mo, Yun-Fei; Liu, Rang-Su; Tian, Ze-An; Liang, Yong-Chao; Zhang, Hai-Tao; Hou, Zhao-Yang; Liu, Hai-Rong; Zhang, Ai-long; Zhou, Li-Li; Peng, Ping; Xie, Zhong

    2015-05-01

    A MD simulation of liquid Cu46Zr54 alloys has been performed for understanding the effects of initial melt temperatures on the microstructural evolution and mechanical properties during quenching process. By using several microstructural analyzing methods, it is found that the icosahedral and defective icosahedral clusters play a key role in the microstructure transition. All the final solidification structures obtained at different initial melt temperatures are of amorphous structures, and their structural and mechanical properties are non-linearly related to the initial melt temperatures, and fluctuated in a certain range. Especially, there exists a best initial melt temperature, from which the glass configuration possesses the highest packing density, the optimal elastic constants, and the smaller extent of structural softening under deforming.

  3. Pulse thermal processing of functional materials using directed plasma arc

    DOEpatents

    Ott, Ronald D.; Blue, Craig A.; Dudney, Nancy J.; Harper, David C.

    2007-05-22

    A method of thermally processing a material includes exposing the material to at least one pulse of infrared light emitted from a directed plasma arc to thermally process the material, the pulse having a duration of no more than 10 s.

  4. A Course on Plasma Processing in Integrated Circuit Fabrication.

    ERIC Educational Resources Information Center

    Sawin, Herbert H.; Reif, Rafael

    1983-01-01

    Describes a course, taught jointly by electrical/chemical engineering departments at the Massachusetts Institute of Technology, designed to teach the fundamental science of plasma processing as well as to give an overview of the present state of industrial processes. Provides rationale for course development, texts used, class composition, and…

  5. Investigation of Recombination Processes In A Magnetized Plasma

    NASA Technical Reports Server (NTRS)

    Chavers, Greg; Chang-Diaz, Franklin; Rodgers, Stephen L. (Technical Monitor)

    2002-01-01

    Interplanetary travel requires propulsion systems that can provide high specific impulse (Isp), while also having sufficient thrust to rapidly accelerate large payloads. One such propulsion system is the Variable Specific Impulse Magneto-plasma Rocket (VASIMR), which creates, heats, and exhausts plasma to provide variable thrust and Isp, optimally meeting the mission requirements. A large fraction of the energy to create the plasma is frozen in the exhaust in the form of ionization energy. This loss mechanism is common to all electromagnetic plasma thrusters and has an impact on their efficiency. When the device operates at high Isp, where the exhaust kinetic energy is high compared to the ionization energy, the frozen flow component is of little consequence; however, at low Isp, the effect of the frozen flow may be important. If some of this energy could be recovered through recombination processes, and re-injected as neutral kinetic energy, the efficiency of VASIMR, in its low Isp/high thrust mode may be improved. In this operating regime, the ionization energy is a large portion of the total plasma energy. An experiment is being conducted to investigate the possibility of recovering some of the energy used to create the plasma. This presentation will cover the progress and status of the experiment involving surface recombination of the plasma.

  6. Apparatus and method for plasma processing of SRF cavities

    NASA Astrophysics Data System (ADS)

    Upadhyay, J.; Im, Do; Peshl, J.; Bašović, M.; Popović, S.; Valente-Feliciano, A.-M.; Phillips, L.; Vušković, L.

    2016-05-01

    An apparatus and a method are described for plasma etching of the inner surface of superconducting radio frequency (SRF) cavities. Accelerator SRF cavities are formed into a variable-diameter cylindrical structure made of bulk niobium, for resonant generation of the particle accelerating field. The etch rate non-uniformity due to depletion of the radicals has been overcome by the simultaneous movement of the gas flow inlet and the inner electrode. An effective shape of the inner electrode to reduce the plasma asymmetry for the coaxial cylindrical rf plasma reactor is determined and implemented in the cavity processing method. The processing was accomplished by moving axially the inner electrode and the gas flow inlet in a step-wise way to establish segmented plasma columns. The test structure was a pillbox cavity made of steel of similar dimension to the standard SRF cavity. This was adopted to experimentally verify the plasma surface reaction on cylindrical structures with variable diameter using the segmented plasma generation approach. The pill box cavity is filled with niobium ring- and disk-type samples and the etch rate of these samples was measured.

  7. Spatially Resolved Atomic and Molecular Spectroscopy in Microelectronics Processing Plasmas

    SciTech Connect

    Hebner, G.A.

    1998-10-14

    Plasma processing of microelectronic materials is strongly dependent on the generation and control of neutral radial and ion species generated in a plasma. For example, process uniformity across a #er is drken by a combination of plasma charged particle and neutral uniformity. Due to extensive rexarch and engineering the current generation of commercial plasma reactors can generate very radially uniform ion distributions, usually better than ~ 2 perwnt as determined by ion saturation measurements. Due in part to the difficulty associated with determining the neutral radial distributions, control of the neutral radical uniformity is less well developed. This abstract will review our recent measurements of the spatial distribution of severaI important atomic and molecukw species in inductively coupled plasmas through C12 / BCIJ / Ar containing gas mixtures. Measured species include the ground state Cl and BC1 densities as well as the metastable argon density. The fbeus of this review will be on the experimental techniques and results. In addition to assisting in the development of a fbndarnental understanding of the important pkunna physics, these measurements have been used to benchmark multi dimensional plasma discharge codes.

  8. Performance enhancement of IPMC by anisotropic plasma etching process

    NASA Astrophysics Data System (ADS)

    Lee, Seok Hwan; Kim, Chul-Jin; Hwang, Hyun-Woo; Kim, Sung-Joo; Yang, Hyun-Seok; Park, No-Cheol; Park, Young-Pil; Park, Kang-Ho; Lee, Hyung-Kun; Choi, Nak-Jin

    2009-03-01

    Ionic Polymer-Metal Composites (IPMCs) of EAP actuators is famous for its good property of response and durability. The performance of Ionic Polymer-Metal Composites (IPMCs) is an important issue which is affected by many factors. There are two factors for deciding the performance of IPMC. By treating anisotropic plasma etching process to 6 models of the IPMCs, enhanced experimental displacement and force results are obtained. Plasma patterning processes are executed by changing the groove and the land length of 6 patterns. The purpose of the present investigation is to find out the major factor which mainly affects the IPMC performance. Simulations using ANSYS have been executed to compare with the experimental results about the values and the tendency of data. Experimental and simulating data of the performances seem to have similar tendency. In the next part of the paper, we observed the other properties like capacitance, resistance and stiffness of 6 plasma patterned IPMCs. And we observed that the stiffness is the major factor which affects the performance of IPMCs. As we seen, our problem has been reduced to investigate about the property of stiffness. We suggest that the stiffness is largely changed mainly because of the different thickness of Platinum stacked of the groove and the land part which are produced by anisotropic plasma etching processes. And we understand that anisotropic plasma patterned IPMCs of better performance can be applied to various applications.

  9. Plasma assisted surface coating/modification processes: An emerging technology

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1986-01-01

    A broad understanding of the numerous ion or plasma assisted surface coating/modification processes is sought. An awareness of the principles of these processes is needed before discussing in detail the ion nitriding technology. On the basis of surface modifications arising from ion or plasma energizing and interactions, it can be broadly classified as deposition of distinct overlay coatings (sputtering-dc, radio frequency, magnetron, reactive; ion plating-diode, triode) and surface property modification without forming a discrete coating (ion implantation, ion beam mixing, laser beam irradiation, ion nitriding, ion carburizing, plasma oxidation). These techniques offer a great flexibility and are capable in tailoring desirable chemical and structural surface properties independent of the bulk properties.

  10. Quantum tunneling resonant electron transfer process in Lorentzian plasmas

    SciTech Connect

    Hong, Woo-Pyo; Jung, Young-Dae

    2014-08-15

    The quantum tunneling resonant electron transfer process between a positive ion and a neutral atom collision is investigated in nonthermal generalized Lorentzian plasmas. The result shows that the nonthermal effect enhances the resonant electron transfer cross section in Lorentzian plasmas. It is found that the nonthermal effect on the classical resonant electron transfer cross section is more significant than that on the quantum tunneling resonant charge transfer cross section. It is shown that the nonthermal effect on the resonant electron transfer cross section decreases with an increase of the Debye length. In addition, the nonthermal effect on the quantum tunneling resonant electron transfer cross section decreases with increasing collision energy. The variation of nonthermal and plasma shielding effects on the quantum tunneling resonant electron transfer process is also discussed.

  11. Diagnostic techniques in thermal plasma processing (Part II). Volume 2

    SciTech Connect

    Boulos, M.; Fauchais, P.; Pfender, E.

    1986-02-01

    Techniques for diagnostics for thermal plasmas are discussed. These include both optical techniques and in-flight measurements of particulate matter. In the core of the plasma, collisional excitation of the various chemical species is so strong that the population of the corresponding quantum levels becomes high enough for net emission from the plasma. In that case, the classical methods of emission spectroscopy may be applied. But in the regions where the temperatures are below 4000/sup 0/K (these regions are of primary importance for plasma processing), the emission from the plasma is no longer sufficient for emission spectroscopy. In this situation, the population of excited levels must be increased by the absorption of the light from an external source. Such sources, as for example pulsed tunable dye lasers, are now commercially available. The use of such new devices leads to various techniques such as laser induced fluorescence (LIF) or Coherent Anti Stockes Raman Spectroscopy (CARS) that can be used for analyzing plasmas. Particle velocity measurements can be achieved by photography and laser Doppler anemometry. Particle flux measurements are typically achieved by collecting particles on a substrate. Particle size measurements are based on intensity of scattered light. (WRF)

  12. Electron-beam generated plasmas for processing applications

    NASA Astrophysics Data System (ADS)

    Meger, Robert; Leonhardt, Darrin; Murphy, Donald; Walton, Scott; Blackwell, David; Fernsler, Richard; Lampe, Martin; Manheimer, Wallace

    2001-10-01

    NRL's Large Area Plasma Processing System (LAPPS) utilizes a 5-10 mA/cm^2, 2-4 kV, 1 cm x 30-60 cm cross section beam of electrons guided by a magnetic field to ionize a low density (10-100 mTorr) gas.[1] Beam ionization allows large area, high density, low temperature plasmas to be generated in an arbitrary gas mixture at a well defined location. Energy and composition of particle fluxes to surfaces on both sides of the plasma can be controlled by gas mixture, location, rf bias, and other factors. Experiments have been performed using both pulsed and cw beams. Extensive diagnostics (Langmuir probes, mass and ion energy analyzers, optical emissions, microwave interferometry, etc.) have been fielded to measure the plasma properties and neutral particle fluxes (ions, neutrals, free radicals) with and without rf bias on nearby surfaces both with the beam on and off. Uniform, cold (Te < 1eV), dense (ne 10^13 cm-3) plasmas in molecular and atomic gases and mixtures thereof have been produced in agreement with theoretical expectations. Initial tests of LAPPS application such as ashing, etching, sputtering, and diamond growth have been performed. Program status will be presented. [1]R.A. Meger, et al, Phys. of Plasmas 8(5), p. 2558 (2001)

  13. Analysis of processes in DC arc plasma torches for spraying that use air as plasma forming gas

    NASA Astrophysics Data System (ADS)

    Frolov, V.; Ivanov, D.; Toropchin, A.

    2014-11-01

    Developed in Saint Petersburg State Polytechnical University technological processes of air-plasma spraying of wear-resistant, regenerating, hardening and decorative coatings used in number of industrial areas are described. The article contains examples of applications of air plasma spraying of coatings as well as results of mathematical modelling of processes in air plasma torches for spraying.

  14. Cold Plasma as a nonthermal food processing technology

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Contamination of fresh and fresh-cut fruits and vegetables by foodborne pathogens has prompted research into novel interventions. Cold plasma is a nonthermal food processing technology which uses energetic, reactive gases to inactivate contaminating microbes. This flexible sanitizing method uses ele...

  15. Potassium plasma cell facilitates thermionic energy conversion process

    NASA Technical Reports Server (NTRS)

    Richards, H. K.

    1967-01-01

    Thermionic energy converter converts nuclear generated heat directly into high frequency and direct current output. It consists of a potassium plasma cell, a tantalum emitter, and a silver plated copper collector. This conversion process eliminates the steam interface usually required between the atomic heat source and the electrical conversion system.

  16. Cold plasma as a nonthermal food processing technology

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Contamination of meats, seafood, poultry, eggs, and fresh and fresh-cut fruits and vegetables is an ongoing concern. Although well-established in non-food applications for surface treatment and modification, cold plasma is a relatively new food safety intervention. As a nonthermal food processing te...

  17. Spectral line intensity irreversibility in circulatory plasma magnetization processes

    SciTech Connect

    Qu, Z. Q.; Dun, G. T.

    2012-01-23

    Spectral line intensity variation is found to be irreversible in circulatory plasma magnetization process by experiments described in this paper, i.e., the curves illustrating spectral line photon fluxes irradiated from a light source immerged in a magnetic field by increasing the magnetic induction cannot be reproduced by decreasing the magnetic induction within the errors. There are two plasma magnetization patterns found. One shows that the intensities are greater at the same magnetic inductions during the magnetic induction decreasing process after the increasing, and the other gives the opposite effect. This reveals that the magneto-induced excitation and de-excitation process is irreversible like ferromagnetic magnetization. But the two irreversible processes are very different in many aspects stated in the text.

  18. Quench Protection for the MICE Cooling Channel Coupling Magnet

    SciTech Connect

    Guo, Xing Long; Xu, Feng Yu; Wang, Li; Green, Michael A.; Pan, Heng; Wu, Hong; Liu, X.K.; Jia, Lin Xiang; Amm, Kathleen

    2008-08-02

    This paper describes the passive quench protection system selected for the muon ionization cooling experiment (MICE) cooling channel coupling magnet. The MICE coupling magnet will employ two methods of quench protection simultaneously. The most important method of quench protection in the coupling magnet is the subdivision of the coil. Cold diodes and resistors are put across the subdivisions to reduce both the voltage to ground and the hot-spot temperature. The second method of quench protection is quench-back from the mandrel, which speeds up the spread of the normal region within the coils. Combining quench back with coil subdivision will reduce the hot spot temperature further. This paper explores the effect on the quench process of the number of coil sub-divisions, the quench propagation velocity within the magnet, and the shunt resistance.

  19. Quench Protection and Magnet Supply Requirements for the MICEFocusingand Coupling Magnets

    SciTech Connect

    Green, Michael A.; Witte, Holger

    2005-06-08

    This report discusses the quench protection and power supply requirements of the MICE superconducting magnets. A section of the report discusses the quench process and how to calculate the peak voltages and hotspot temperature that result from a magnet quench. A section of the report discusses conventional quench protection methods. Thermal quench back from the magnet mandrel is also discussed. Selected quench protection methods that result in safe quenching of the MICE focusing and coupling magnets are discussed. The coupling of the MICE magnets with the other magnets in the MICE is described. The consequences of this coupling on magnet charging and quenching are discussed. Calculations of the quenching of a magnet due quench back from circulating currents induced in the magnet mandrel due to quenching of an adjacent magnet are discussed. The conclusion of this report describes how the MICE magnet channel will react when one or magnets in that channel are quenched.

  20. Generation of low-temperature air plasma for food processing

    NASA Astrophysics Data System (ADS)

    Stepanova, Olga; Demidova, Maria; Astafiev, Alexander; Pinchuk, Mikhail; Balkir, Pinar; Turantas, Fulya

    2015-11-01

    The project is aimed at developing a physical and technical foundation of generating plasma with low gas temperature at atmospheric pressure for food industry needs. As known, plasma has an antimicrobial effect on the numerous types of microorganisms, including those that cause food spoilage. In this work an original experimental setup has been developed for the treatment of different foods. It is based on initiating corona or dielectric-barrier discharge in a chamber filled with ambient air in combination with a certain helium admixture. The experimental setup provides various conditions of discharge generation (including discharge gap geometry, supply voltage, velocity of gas flow, content of helium admixture in air and working pressure) and allows for the measurement of the electrical discharge parameters. Some recommendations on choosing optimal conditions of discharge generation for experiments on plasma food processing are developed.

  1. Atomic Processes and Diagnostics of Low Pressure Krypton Plasma

    NASA Astrophysics Data System (ADS)

    Srivastava, Rajesh; Goyal, Dipti; Gangwar, Reetesh; Stafford, Luc

    2015-03-01

    Optical emission spectroscopy along with suitable collisional-radiative (CR) model is used in plasma diagnostics. Importance of reliable cross-sections for various atomic processes is shown for low pressure argon plasma. In the present work, radially-averaged Kr emission lines from the 2pi --> 1sj were recorded as a function of pressure from 1 to 50mTorr. We have developed a CR model using our fine-structure relativistic-distorted wave cross sections. The various processes considered are electron-impact excitation, ionization and their reverse processes. The required rate coefficients have been calculated from these cross-sections assuming Maxwellian energy distribution. Electron temperature obtained from the CR model is found to be in good agreement with the probe measurements. Work is supported by IAEA Vienna, DAE-BRNS Mumbai and CSIR, New Delhi.

  2. Plasma process optimization for N-type doping applications

    NASA Astrophysics Data System (ADS)

    Raj, Deven; Persing, Harold; Salimian, Siamak; Lacey, Kerry; Qin, Shu; Hu, Jeff Y.; McTeer, Allen

    2012-11-01

    Plasma doping (PLAD) has been adopted across the implant technology space and into high volume production for both conventional DRAM and NAND doping applications. PLAD has established itself as an alternative to traditional ion implantation by beamline implantation. The push for high doping concentration, shallow doping depth, and conformal doping capability expand the need for a PLAD solution to meet such requirements. The unique doping profile and doping characteristics at high dose rates allow for PLAD to deliver a high throughput, differentiated solution to meet the demand of evolving transistor technology. In the PLAD process, ions are accelerated to the wafer as with a negative wafer bias applied to the wafer. Competing mechanisms, such as deposition, sputtering, and etching inherent in plasma doping require unique control and process optimization. In this work, we look at the distinctive process tool control and characterization features which enable an optimized doping process using n-type (PH3 or AsH3) chemistries. The data in this paper will draw the relationship between process optimization through plasma chemistry study to the wafer level result.

  3. Plasma process optimization for N-type doping applications

    SciTech Connect

    Raj, Deven; Persing, Harold; Salimian, Siamak; Lacey, Kerry; Qin Shu; Hu, Jeff Y.; McTeer, Allen

    2012-11-06

    Plasma doping (PLAD) has been adopted across the implant technology space and into high volume production for both conventional DRAM and NAND doping applications. PLAD has established itself as an alternative to traditional ion implantation by beamline implantation. The push for high doping concentration, shallow doping depth, and conformal doping capability expand the need for a PLAD solution to meet such requirements. The unique doping profile and doping characteristics at high dose rates allow for PLAD to deliver a high throughput, differentiated solution to meet the demand of evolving transistor technology. In the PLAD process, ions are accelerated to the wafer as with a negative wafer bias applied to the wafer. Competing mechanisms, such as deposition, sputtering, and etching inherent in plasma doping require unique control and process optimization. In this work, we look at the distinctive process tool control and characterization features which enable an optimized doping process using n-type (PH{sub 3} or AsH{sub 3}) chemistries. The data in this paper will draw the relationship between process optimization through plasma chemistry study to the wafer level result.

  4. 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.

  5. Thinning segregated graphene layers on high carbon solubility substrates of rhodium foils by tuning the quenching process.

    PubMed

    Liu, Mengxi; Zhang, Yanfeng; Chen, Yubin; Gao, Yabo; Gao, Teng; Ma, Donglin; Ji, Qingqing; Zhang, Yu; Li, Cong; Liu, Zhongfan

    2012-12-21

    We report the synthesis of large-scale uniform graphene films on high carbon solubility substrates of Rh foils for the first time using an ambient-pressure chemical vapor deposition method. We find that, by increasing the cooling rate in the growth process, the thickness of graphene can be tuned from multilayer to monolayer, resulting from the different segregation amount of carbon atoms from bulk to surface. The growth feature was characterized with scanning electron microscopy, Raman spectra, transmission electron microscopy, and scanning tunneling microscopy. We also find that bilayer or few-layer graphene prefers to stack deviating from the Bernal stacking geometry, with the formation of versatile moiré patterns. On the basis of these results, we put forward a segregation growth mechanism for graphene growth on Rh foils. Of particular importance, we propose that this randomly stacked few-layer graphene can be a model system for exploring some fantastic physical properties such as van Hove singularities.

  6. Lattice Boltzmann study of hydrodynamic effects in lamellar ordering process of two-dimensional quenched block copolymers.

    PubMed

    Song, Kai-Xu; Jia, Yu-Xi; Sun, Zhao-Yan; An, Li-Jia

    2008-10-14

    By incorporating self-consistent field theory with lattice Boltzmann method, a model for polymer melts is proposed. Compared with models based on Ginzburg-Landau free energy, our model does not employ phenomenological free energies to describe systems and can consider the chain topological details of polymers. We use this model to study the effects of hydrodynamic interactions on the dynamics of microphase separation for block copolymers. In the early stage of phase separation, an exponential growth predicted by Cahn-Hilliard treatment is found. Simulation results also show that the effect of hydrodynamic interactions can be neglected in the early stage. For the late stage of phase separation, it is easy to see the effects of hydrodynamic interactions on the ordering process of lamellae phase. From the analysis of structure factor curves, we find that the growth of domains is faster if hydrodynamic interactions are introduced. Furthermore, the scaling of the pattern dynamics is investigated for the late stage at zero thermal noise. By studying the behavior of scaling exponents of the structure factor and the nematic order-parameter correlation function C(nn), we can see that the effects of hydrodynamic interactions lead to bigger growth exponent for both functions. PMID:19045162

  7. Collisional and radiative processes in high-pressure discharge plasmas

    NASA Astrophysics Data System (ADS)

    Becker, Kurt H.; Kurunczi, Peter F.; Schoenbach, Karl H.

    2002-05-01

    Discharge plasmas at high pressures (up to and exceeding atmospheric pressure), where single collision conditions no longer prevail, provide a fertile environment for the experimental study of collisions and radiative processes dominated by (i) step-wise processes, i.e., the excitation of an already excited atomic/molecular state and by (ii) three-body collisions leading, for instance, to the formation of excimers. The dominance of collisional and radiative processes beyond binary collisions involving ground-state atoms and molecules in such environments allows for many interesting applications of high-pressure plasmas such as high power lasers, opening switches, novel plasma processing applications and sputtering, absorbers and reflectors for electromagnetic waves, remediation of pollutants and waste streams, and excimer lamps and other noncoherent vacuum-ultraviolet light sources. Here recent progress is summarized in the use of hollow cathode discharge devices with hole dimensions in the range 0.1-0.5 mm for the generation of vacuum-ultraviolet light.

  8. Plasma process control for improved PEO coatings on magnesium alloys

    NASA Astrophysics Data System (ADS)

    Hussein, Riyad Omran

    Plasma Electrolytic Oxidation (PEO) is a high voltage plasma-assisted oxidation process uses an environmentally-friendly aqueous electrolyte to oxidize the metal surfaces to form ceramic oxide coatings which impart a high corrosion and wear resistance. One of the main advantages of PEO process is that it can be applied to treat samples with complex shapes, and surfaces with different composition and microstructure. The PEO process of Mg alloys is strongly influenced by such parameters as electrolyte composition and concentration, current or voltage applied and substrate alloy. Generally, these parameters have a direct influence on the discharging behavior. The discharges play an essential role in the formation and resulting composition of the 3-layer oxide structure. A detailed knowledge of the coating mechanisms is extremely important in order to produce a desired coating quality to reach the best performance of the PEO coatings in terms of corrosion resistance and tribological properties (wear rate, COF). During PEO processing of magnesium, some of the metal cations are transferred outwards from the substrate and react with anions to form ceramic coatings. Also, due to the high electric field in the discharge channels, oxygen anions transfer towards the magnesium substrate and react with Mg2+ cations to form a ceramic coating. Although, in general, PEO coating of Mg alloys produces the three-layered structure, the relative proportions of the three-layers are strongly influenced by the PEO processing parameters. In PEO process, the ceramic coating grows inwards to the alloy substrate and outwards to the coating surface simultaneously. For the coating growth, there are three simultaneous processes taking place, namely the electrochemical, the plasma chemical reactions and thermal diffusion. Optical emission spectroscopy (OES) was employed for the discharge characterization by following the substrate and electrolyte element present in the plasma discharge during the

  9. Magnetohydrodynamic turbulence and enhanced atomic processes in astrophysical plasmas

    NASA Astrophysics Data System (ADS)

    Spangler, Steven R.

    1998-08-01

    This article discusses a way in which enhanced atomic physics processes, including radiative energy losses, may occur in an astrophysical plasma containing magnetohydrodynamic turbulence. Two-dimensional (2D) magnetohydrodynamics (MHD) is adopted as a model. A major characteristic feature of 2D MHD turbulence is the development of strong current sheets on a dynamical time scale L/V0 where L is the spatial scale of the turbulent fluid and V0 is the scale of the velocity fluctuations. The current contained in the sheets will be carried by an electron drift relative to the ions. The case of a plasma containing minority atoms or ions with an excited state accessible to collisions from the tail of the electron distribution is considered. In the current carrying sheets or filaments, the electron distribution function will be perturbed such that collisional excitations will be enhanced relative to the current-free plasma. Subsequent radiative de-excitation of the atoms or ions removes energy from the turbulence. Expressions are presented for the electron drift velocity arising in 2D turbulence, the enhancement of collisional excitations of a trace atom or ion, and the energy lost to the plasma turbulence by radiative de-excitation of these atoms or ions. The mechanism would be most pronounced in plasmas for which the magnitude of the magnetic field is large, the outer scale of the turbulence is small, and the electron density and temperature are low. A brief discussion of the relevance of this mechanism to some specific astrophysical plasmas is given.

  10. Atmospheric Pressure Plasma-Electrospin Hybrid Process for Protective Applications

    NASA Astrophysics Data System (ADS)

    Vitchuli Gangadharan, Narendiran

    2011-12-01

    Chemical and biological (C-B) warfare agents like sarin, sulfur mustard, anthrax are usually dispersed into atmosphere in the form of micro aerosols. They are considered to be dangerous weapon of mass destruction next to nuclear weapons. The airtight protective clothing materials currently available are able to stop the diffusion of threat agents but not good enough to detoxify them, which endangers the wearers. Extensive research efforts are being made to prepare advanced protective clothing materials that not only prevent the diffusion of C-B agents, but also detoxify them into harmless products thus ensuring the safety and comfort of the wearer. Electrospun nanofiber mats are considered to have effective filtration characteristics to stop the diffusion of submicron level particulates without sacrificing air permeability characteristics and could be used in protective application as barrier material. In addition, functional nanofibers could be potentially developed to detoxify the C-B warfare threats into harmless products. In this research, electrospun nanofibers were deposited on fabric surface to improve barrier efficiency without sacrificing comfort-related properties of the fabrics. Multi-functional nanofibers were fabricated through an electrospinning-electrospraying hybrid process and their ability to detoxify simulants of C-B agents was evaluated. Nanofibers were also deposited onto plasma-pretreated woven fabric substrate through a newly developed plasma-electrospinning hybrid process, to improve the adhesive properties of nanofibers on the fabric surface. The nanofiber adhesion and durability properties were evaluated by peel test, flex and abrasion resistance tests. In this research work, following tasks have been carried out: i) Controlled deposition of nanofiber mat onto woven fabric substrate Electrospun Nylon 6 fiber mats were deposited onto woven 50/50 Nylon/Cotton fabric with the motive of making them into protective material against submicron

  11. Atmospheric Pressure Plasma-Electrospin Hybrid Process for Protective Applications

    NASA Astrophysics Data System (ADS)

    Vitchuli Gangadharan, Narendiran

    2011-12-01

    Chemical and biological (C-B) warfare agents like sarin, sulfur mustard, anthrax are usually dispersed into atmosphere in the form of micro aerosols. They are considered to be dangerous weapon of mass destruction next to nuclear weapons. The airtight protective clothing materials currently available are able to stop the diffusion of threat agents but not good enough to detoxify them, which endangers the wearers. Extensive research efforts are being made to prepare advanced protective clothing materials that not only prevent the diffusion of C-B agents, but also detoxify them into harmless products thus ensuring the safety and comfort of the wearer. Electrospun nanofiber mats are considered to have effective filtration characteristics to stop the diffusion of submicron level particulates without sacrificing air permeability characteristics and could be used in protective application as barrier material. In addition, functional nanofibers could be potentially developed to detoxify the C-B warfare threats into harmless products. In this research, electrospun nanofibers were deposited on fabric surface to improve barrier efficiency without sacrificing comfort-related properties of the fabrics. Multi-functional nanofibers were fabricated through an electrospinning-electrospraying hybrid process and their ability to detoxify simulants of C-B agents was evaluated. Nanofibers were also deposited onto plasma-pretreated woven fabric substrate through a newly developed plasma-electrospinning hybrid process, to improve the adhesive properties of nanofibers on the fabric surface. The nanofiber adhesion and durability properties were evaluated by peel test, flex and abrasion resistance tests. In this research work, following tasks have been carried out: i) Controlled deposition of nanofiber mat onto woven fabric substrate Electrospun Nylon 6 fiber mats were deposited onto woven 50/50 Nylon/Cotton fabric with the motive of making them into protective material against submicron

  12. Plasma nitriding monitoring reactor: A model reactor for studying plasma nitriding processes using an active screen

    NASA Astrophysics Data System (ADS)

    Hamann, S.; Börner, K.; Burlacov, I.; Spies, H.-J.; Strämke, M.; Strämke, S.; Röpcke, J.

    2015-12-01

    A laboratory scale plasma nitriding monitoring reactor (PLANIMOR) has been designed to study the basics of active screen plasma nitriding (ASPN) processes. PLANIMOR consists of a tube reactor vessel, made of borosilicate glass, enabling optical emission spectroscopy (OES) and infrared absorption spectroscopy. The linear setup of the electrode system of the reactor has the advantages to apply the diagnostic approaches on each part of the plasma process, separately. Furthermore, possible changes of the electrical field and of the heat generation, as they could appear in down-scaled cylindrical ASPN reactors, are avoided. PLANIMOR has been used for the nitriding of steel samples, achieving similar results as in an industrial scale ASPN reactor. A compact spectrometer using an external cavity quantum cascade laser combined with an optical multi-pass cell has been applied for the detection of molecular reaction products. This allowed the determination of the concentrations of four stable molecular species (CH4, C2H2, HCN, and NH3). With the help of OES, the rotational temperature of the screen plasma could be determined.

  13. Plasma nitriding monitoring reactor: A model reactor for studying plasma nitriding processes using an active screen

    SciTech Connect

    Hamann, S. Röpcke, J.; Börner, K.; Burlacov, I.; Spies, H.-J.; Strämke, M.; Strämke, S.

    2015-12-15

    A laboratory scale plasma nitriding monitoring reactor (PLANIMOR) has been designed to study the basics of active screen plasma nitriding (ASPN) processes. PLANIMOR consists of a tube reactor vessel, made of borosilicate glass, enabling optical emission spectroscopy (OES) and infrared absorption spectroscopy. The linear setup of the electrode system of the reactor has the advantages to apply the diagnostic approaches on each part of the plasma process, separately. Furthermore, possible changes of the electrical field and of the heat generation, as they could appear in down-scaled cylindrical ASPN reactors, are avoided. PLANIMOR has been used for the nitriding of steel samples, achieving similar results as in an industrial scale ASPN reactor. A compact spectrometer using an external cavity quantum cascade laser combined with an optical multi-pass cell has been applied for the detection of molecular reaction products. This allowed the determination of the concentrations of four stable molecular species (CH{sub 4}, C{sub 2}H{sub 2}, HCN, and NH{sub 3}). With the help of OES, the rotational temperature of the screen plasma could be determined.

  14. Plasma nitriding monitoring reactor: A model reactor for studying plasma nitriding processes using an active screen.

    PubMed

    Hamann, S; Börner, K; Burlacov, I; Spies, H-J; Strämke, M; Strämke, S; Röpcke, J

    2015-12-01

    A laboratory scale plasma nitriding monitoring reactor (PLANIMOR) has been designed to study the basics of active screen plasma nitriding (ASPN) processes. PLANIMOR consists of a tube reactor vessel, made of borosilicate glass, enabling optical emission spectroscopy (OES) and infrared absorption spectroscopy. The linear setup of the electrode system of the reactor has the advantages to apply the diagnostic approaches on each part of the plasma process, separately. Furthermore, possible changes of the electrical field and of the heat generation, as they could appear in down-scaled cylindrical ASPN reactors, are avoided. PLANIMOR has been used for the nitriding of steel samples, achieving similar results as in an industrial scale ASPN reactor. A compact spectrometer using an external cavity quantum cascade laser combined with an optical multi-pass cell has been applied for the detection of molecular reaction products. This allowed the determination of the concentrations of four stable molecular species (CH4, C2H2, HCN, and NH3). With the help of OES, the rotational temperature of the screen plasma could be determined. PMID:26724023

  15. Solvent refined coal reactor quench system

    DOEpatents

    Thorogood, R.M.

    1983-11-08

    There is described an improved SRC reactor quench system using a condensed product which is recycled to the reactor and provides cooling by evaporation. In the process, the second and subsequent reactors of a series of reactors are cooled by the addition of a light oil fraction which provides cooling by evaporation in the reactor. The vaporized quench liquid is recondensed from the reactor outlet vapor stream. 1 fig.

  16. Solvent refined coal reactor quench system

    DOEpatents

    Thorogood, Robert M.

    1983-01-01

    There is described an improved SRC reactor quench system using a condensed product which is recycled to the reactor and provides cooling by evaporation. In the process, the second and subsequent reactors of a series of reactors are cooled by the addition of a light oil fraction which provides cooling by evaporation in the reactor. The vaporized quench liquid is recondensed from the reactor outlet vapor stream.

  17. The variable polarity plasma arc welding process: Characteristics and performance

    NASA Technical Reports Server (NTRS)

    Hung, R. J.; Zhu, G. J.

    1991-01-01

    Significant advantages of the Variable Polarity Plasma Arc (VPPA) Welding Process include faster welding, fewer repairs, less joint preparation, reduced weldment distortion, and absence of porosity. The power distribution was analyzed for an argon plasma gas flow constituting the fluid in the VPPA Welding Process. The major heat loss at the torch nozzle is convective heat transfer; in the space between the outlet of the nozzle and the workpiece; radiative heat transfer; and in the keyhole in the workpiece, convective heat transfer. The power absorbed at the workpiece produces the molten puddle that solidifies into the weld bead. Crown and root widths, and crown and root heights of the weld bead are predicted. The basis is provided for an algorithm for automatic control of VPPA welding machine parameters to obtain desired weld bead dimensions.

  18. Wireless sensor technology for in-situ plasma process monitoring

    NASA Astrophysics Data System (ADS)

    Gahan, David

    2015-09-01

    There is an increasing demand for plasma measurement and control solutions to cope with the growing complexity of integrated circuit manufacture in the semiconductor industry. Standard plasma diagnostic instruments used in research, such as the Langmuir probe, are not suitable for use in the production environment for myriad reasons - contamination of the process being one of the main concerns. Silicon wafer based wireless sensors, which measure temperature during the process, have gained the most traction with tool manufacturers and chip makers - albeit during process development or the PM cycle rather than live production. In this presentation we will discuss two novel wireless technologies that have the potential for use in process tools. The first is an ion detector embedded in a silicon wafer. The sensor measures the average ion flux and the maximum ion energy during the process. This information is stored and is downloaded later for analysis. The second technology consists of a wireless sensor that sits inside the process and communicates data in real time to a detector installed on the rf power line. This platform is similar to RFID technology and can be combined with various sensor types to transmit data to the user during the process.

  19. Sensor Driven Intelligent Control System For Plasma Processing

    SciTech Connect

    Bell, G.; Campbell, V.B.

    1998-02-23

    This Cooperative Research and Development Agreement (CRADA) between Innovative Computing Technologies, Inc. (IC Tech) and Martin Marietta Energy Systems (MMES) was undertaken to contribute to improved process control for microelectronic device fabrication. Process data from an amorphous silicon thin film deposition experiment was acquired to validate the performance of an intelligent, adaptive, neurally-inspired control software module designed to provide closed loop control of plasma processing machines used in the microelectronics industry. Data acquisition software was written using LabView The data was collected from an inductively coupled plasma (ICP) source, which was available for this project through LMES's RF/Microwave Technology Center. Experimental parameters measured were RF power, RF current and voltage on the antenna delivering power to the plasma, hydrogen and silane flow rate, chamber pressure, substrate temperature and H-alpha optical emission. Experimental results obtained were poly-crystallin silicon deposition rate, crystallinity, crystallographic orientation and electrical conductivity. Owing to experimental delays resulting from hardware failures, it was not possible to assemble a complete data for IC Tech use within the time and resource constraints of the CRADA. IC Tech was therefore not able to verify the performance of their existing models and control structures and validate model performance under this CRADA.

  20. Quenching: fact or fiction?

    PubMed

    Basketter, D

    2000-11-01

    Fragrance chemicals are a frequently reported cause of allergic contact dermatitis (ACD), a matter which has recently come into considerable prominence, to the point that legislation in Europe is under serious consideration. Certain skin-sensitizing fragrance chemicals have been reported by the producing industry to be rendered safe (quenched), at least in terms of ACD, when they are used in the presence of a specific quenching agent. Accordingly, it seemed timely to review this apparent quenching phenomenon, considering the available data and potential mechanistic hypotheses that might be used to explain it. If it is correct, it should be a phenomenon of potentially enormous value in the elimination of the allergenic properties of at least a proportion of common skin sensitizers. Whilst there is some evidence in man for the occurrence of quenching during the induction of skin sensitization, a much more substantial body of work has failed to find supportive evidence in various animals models, at a chemical level or at elicitation in human subjects with existing allergy. On balance, it is concluded that quenching of fragrance allergens is a phenomenon still awaiting positive evidence of existence.

  1. Diagnostics of Nano-Particle Formation in Process Plasmas

    NASA Astrophysics Data System (ADS)

    Kersten, Holger

    2015-09-01

    The main sources of particle generation during plasma surface processing and the formation of nano-composite materials are (i) the formation of large molecules, mesoscopic clusters and particles in the plasma bulk by chemically reactive gases, and (ii) the formation and incorporation of particles at surfaces (target, substrate) by means of plasma-wall interaction. The plasma process promotes the particle formation by excitation, dissociation and reaction of the involved species in the gas phase. The different stages of the particle growth in the gas phase can be observed by various plasma diagnostics as mass spectrometry, laser induced evaporation, photo-detachment, IR absorption, microwave cavity measurements, Mie scattering and self-excited electron resonance spectroscopy (SEERS). Common diagnostics of particle formation also use the observation and analysis of harmonics and other discharge characteristics. Especially the early stages of the particle growth are not well investigated since they are experimentally inaccessible by standard methods as mentioned above. A novel collection method based on neutral drag was tested in order to get a better insight into the early stages of particle growth. The experiments were performed in an asymmetric, capacitively coupled rf-discharge, where multiple growth cycles can be obtained. Making use of the correlation between the particle growth cycles and the bias voltage as well as the phase angle between discharge current and voltage it was possible to monitor each growth process in-situ. This allowed to collect particles at any desired stage of the growth cycle via the neutral drag method. Size distributions of the nanoparticles at the different stages of the growth cycle were determined ex-situ by transmission electron microscopy. The observed correlations of particle size and bias voltage, which can be used for prediction of the particle growth, are qualitatively explained. Furthermore, the change of the electron density

  2. Reactive atom plasma (RAP) processing of mirrors for astronomy

    NASA Astrophysics Data System (ADS)

    Subrahmanyan, Pradeep K.; Gardopée, George

    2008-07-01

    Modern day telescopes for astronomy have very complex requirements. Both ground and space based telescopes are getting much larger placing significant productivity requirements on the manufacturing processes employed. Conventional manufacturing paradigms involving mechanical abrasion have limitations related primarily to the material removal mechanisms employed. Reactive Atom Plasma (RAPTM) processing is a sub-aperture, non-contact, deterministic figuring technology performed at atmospheric pressures. The process has high material removal rates, and given the non-contact and atmospheric nature lends itself very well to scaling up for large aperture mirrors/segments. The process also benefits from its ability to simultaneously remove sub-surface damage (SSD) while imparting the desired figure to the surface. Developments are under way currently to scale the process up towards larger clear apertures while being able to figure in high spatial frequency features.

  3. Process control using new approaches in plasma diagnostics

    NASA Astrophysics Data System (ADS)

    Reeves, Steve; Fullwood, Clayton; Turner, Terry R.

    1994-09-01

    As semiconductor processing requirements evolve to meet the demands of decreasing geometries, new approached in plasma metrology will be needed to monitor the performances of the equipment and its processes. This performance has traditionally been monitored via Statistical Process Control (SPC) on output parameters such as etch rate and uniformity. These measurements are typically taken on single film wafers which may not be an accurate representation of product. With emerging, nonintrusive, RF sensor technology, equipment and process engineers have access to signals which provide better resolution in determining the health of the equipment. This paper will discuss the relationships between machine settings, real-time RF sensor measurements and the etch rate and uniformity metrics typically used in machine/process qualifications. Run to run control algorithms using the RF sensor measurements will also be presented. Finally, the implications of using RF sensor measurements to provide real-time closed loop control of machine settings will be discussed.

  4. Experimental studies of ionospheric irregularities and related plasma processes

    NASA Technical Reports Server (NTRS)

    Baker, Kay D.

    1992-01-01

    Utah State University (USU) continued its program of measuring and interpreting electron density and its variations in a variety of ionospheric conditions with the Experimental Studies of Ionospheric Irregularities and Related Plasma Processes program. The program represented a nearly ten year effort to provide key measurements of electron density and its fluctuations using sounding rockets. The program also involved the joint interpretation of the results in terms of ionospheric processes. A complete campaign summary and a brief description of the major rocket campaigns are also included.

  5. Process Control in Production-Worthy Plasma Doping Technology

    SciTech Connect

    Winder, Edmund J.; Fang Ziwei; Arevalo, Edwin; Miller, Tim; Persing, Harold; Singh, Vikram; Parrill, T. M.

    2006-11-13

    As the semiconductor industry continues to scale devices of smaller dimensions and improved performance, many ion implantation processes require lower energy and higher doses. Achieving these high doses (in some cases {approx}1x1016 ions/cm2) at low energies (<3 keV) while maintaining throughput is increasingly challenging for traditional beamline implant tools because of space-charge effects that limit achievable beam density at low energies. Plasma doping is recognized as a technology which can overcome this problem. In this paper, we highlight the technology available to achieve process control for all implant parameters associated with modem semiconductor manufacturing.

  6. The Quench Action

    NASA Astrophysics Data System (ADS)

    Caux, Jean-Sébastien

    2016-06-01

    We give a pedagogical introduction to the methodology of the Quench Action, which is an effective representation for the calculation of time-dependent expectation values of physical operators following a generic out-of-equilibrium state preparation protocol (for example a quantum quench). The representation, originally introduced in Caux and Essler (2013 Phys. Rev. Lett. 110 257203), is founded on a mixture of exact data for overlaps together with variational reasonings. It is argued to be quite generally valid and thermodynamically exact for arbitrary times after the quench (from short times all the way up to the steady state), and applicable to a wide class of physically relevant observables. Here, we introduce the method and its language, give an overview of some recent results, suggest a roadmap and offer some perspectives on possible future research directions.

  7. Dynamic processes and polarizability of sodium atom in Debye plasmas

    SciTech Connect

    Qi, Yue-Ying Ning, Li-Na

    2014-03-15

    Dynamic processes including excitation and ionization, and spectrum parameters including the oscillator strengths, dipole polarizabilities from the orbital 3s,3p of sodium atom embedded in weakly coupled plasma are investigated in the entire energy range of a non-relativistic regime. The interaction between the valence electron and the atomic core is simulated by a model potential, and the plasma screening of the Coulomb interaction between charged particles is described by the Debye-Hückel model. The screening of Coulomb interactions reduces the number of bound states, decreases their binding energies, broadens their radial distribution of electron wave functions, and significantly changes the continuum wave functions including the amplitudes and phase-shift. These changes strongly affect the dipole matrix elements between the bound-bound and bound-continuum states, and even the oscillator strengths, the photo-ionization cross sections and the dipole polarizabilities. The plasma screening effect changes the interaction between the valence electron and the atomic core into a short-range potential. The energy behaviors of photo-ionization cross sections are unfolded, for instance, its low-energy behavior (obeying Wigner threshold law), and the appearance of multiple shape and virtual-state resonances when the upper bound states emerge into the continuum. The Combet-Farnoux and Cooper minima in the photo-ionization cross sections are also investigated, and here, the Cooper minima appear not only for the l→l+1 channel but also for l→l−1 one, different from that of hydrogen-like ions in a Debye plasma, which appear only in the l→l+1 channel. The total static electric dipole polarizabilities monotonously and dramatically increase with the plasma screening effect increasing, which are similar to those of hydrogen-like ions and lithium atom. Comparison of calculated results for the oscillator strength, the photo-ionization cross section and polarizability with

  8. Characterization of microwave discharge plasmas for surface processing

    NASA Astrophysics Data System (ADS)

    Nikolic, Milka

    We have developed several diagnostic techniques to characterize two types of microwave (MW) discharge plasmas: a supersonic flowing argon MW discharge maintained in a cylindrical quartz cavity at frequency ƒ = 2.45 GHz and a pulse repetitive MW discharge in air at ƒ = 9.5 GHz. Low temperature MW discharges have been proven to posses attractive properties for plasma cleaning and etching of niobium surfaces of superconductive radio frequency (SRF) cavities. Plasma based surface modification technologies offer a promising alternative for etching and cleaning of SRF cavities. These technologies are low cost, environmentally friendly and easily controllable, and present a possible alternative to currently used acid based wet technologies, such as buffered chemical polishing (BCP), or electrochemical polishing (EP). In fact, weakly ionized. non-equilibrium, and low temperature gas discharges represent a powerful tool for surface processing due to the strong chemical reactivity of plasma radicals. Therefore, characterizing these discharges by applying non-perturbing, in situ measurement techniques is of vital importance. Optical emission spectroscopy has been employed to analyze the molecular structure and evaluate rotational and vibrational temperatures in these discharges. The internal plasma structure was studied by applying a tomographic numerical method based on the two-dimensional Radon formula. An automated optical measurement system has been developed for reconstruction of local plasma parameters. It was found that excited argon states are concentrated near the tube walls, thus confirming the assumption that the post discharge plasma is dominantly sustained by a travelling surface wave. Employing a laser induced fluorescence technique in combination with the time synchronization device allowed us to obtain time-resolved population densities of some excited atomic levels in argon. We have developed a technique for absolute measurements of electron density based

  9. Constraining fundamental plasma physics processes using doped capsule implosions

    NASA Astrophysics Data System (ADS)

    Garbett, W. J.; James, S.; Kyrala, G. A.; Wilson, D. C.; Benage, J.; Wysocki, F. J.; Gunderson, M.; Frenje, J.; Petrasso, R.; Glebov, V. Y.; Yaakobi, B.

    2008-05-01

    A standard technique in inertial confinement fusion research is the use of low levels of spectroscopic dopants as a passive diagnostic of fuel conditions. Using higher dopant levels it becomes possible to modify the plasma conditions. Doped capsule experiments may thus provide a way to control and study fundamental plasma physics processes in the inertial fusion regime. As a precursor to eventual experiments on the National Ignition Facility (NIF) we have performed a series of capsule implosions using the Omega laser. These are intended to guide the modelling of high-Z dopants and explore the feasibility of using such capsule implosions for quantitative physics experiments. We have fielded thin glass shells filled with D-He3 fuel and varying levels of Ar, Kr and Xe dopants. X-ray emission spectroscopy is combined with simultaneous measurements of primary neutron and proton yields and energy spectra in an attempt to fully constrain capsule behaviour.

  10. Advanced Plasma Pyrolysis Assembly (PPA) Reactor and Process Development

    NASA Technical Reports Server (NTRS)

    Wheeler, Richard R., Jr.; Hadley, Neal M.; Dahl, Roger W.; Abney, Morgan B.; Greenwood, Zachary; Miller, Lee; Medlen, Amber

    2012-01-01

    Design and development of a second generation Plasma Pyrolysis Assembly (PPA) reactor is currently underway as part of NASA's Atmosphere Revitalization Resource Recovery effort. By recovering up to 75% of the hydrogen currently lost as methane in the Sabatier reactor effluent, the PPA helps to minimize life support resupply costs for extended duration missions. To date, second generation PPA development has demonstrated significant technology advancements over the first generation device by doubling the methane processing rate while, at the same time, more than halving the required power. One development area of particular interest to NASA system engineers is fouling of the PPA reactor with carbonaceous products. As a mitigation plan, NASA MSFC has explored the feasibility of using an oxidative plasma based upon metabolic CO2 to regenerate the reactor window and gas inlet ports. The results and implications of this testing are addressed along with the advanced PPA reactor development.

  11. Plasma Regimes in the Surroundings of Black Holes, Composite Plasma Disk Structures and Relevant Accretion Processes

    NASA Astrophysics Data System (ADS)

    Coppi, Bruno

    2010-06-01

    The theory of the composite plasma disk structures and of the relevant magnetic field configurations that can surround black holes is presented, consistently with recent experimental observations indicating that highly coherent magnetic field configurations exist in the core of these structures. Concepts developed to describe the physics of magnetically confined laboratory plasmas are used. Thus the ``paradox,'' that arises when considering accreting plasmas in the presence of a transverse magnetic field is resolved by considering accretion as an intermittent process whereby particles are carried in steps, along a sequence of magnetic separatrices containing the formed magnetic islands, by the onset of the equivalent of ``edge localized modes'' (ELMs) observed in laboratory experiments. Inactive galactic black holes are suggested as being associated with older galaxies that have been subjected to collisions destroying the coherent structures needed to guide relevant accretion flows. Alternatively, tridimensional spiral structures can emerge from axisymmetric disk configurations in a region close to the black hole and guide the relevant accretion flows. The radial gradient of the rotation frequency and the vertical gradient of the plasma pressure are the excitation factors for spirals as well as for axisymmetric modes. These can produce vertical flows of thermal energy and particles in opposing directions that can be connected to the winds emanating from disks in Active Galactic Nuclei (AGNs). In the close vicinity of Binary Black Holes the existence of three characteristic plasma regions is envisioned. The intermediate of these regions exhibits three physical regimes that differ both for the magnetic field structure and the spectrum of the emitted radiation, with jets and High Frequency Periodic Oscillations (HFQPOs) produced in two of these regimes.

  12. Process maps for plasma spray: Part 1: Plasma-particle interactions

    SciTech Connect

    GILMORE,DELWYN L.; NEISER JR.,RICHARD A.; WAN,YUEPENG; SAMPATH,SANJAY

    2000-01-26

    This is the first paper of a two part series based on an integrated study carried out at Sandia National Laboratories and the State University of New York at Stony Brook. The aim of the study is to develop a more fundamental understanding of plasma-particle interactions, droplet-substrate interactions, deposit formation dynamics and microstructural development as well as final deposit properties. The purpose is to create models that can be used to link processing to performance. Process maps have been developed for air plasma spray of molybdenum. Experimental work was done to investigate the importance of such spray parameters as gun current, auxiliary gas flow, and powder carrier gas flow. In-flight particle diameters, temperatures, and velocities were measured in various areas of the spray plume. Samples were produced for analysis of microstructures and properties. An empirical model was developed, relating the input parameters to the in-flight particle characteristics. Multi-dimensional numerical simulations of the plasma gas flow field and in-flight particles under different operating conditions were also performed. In addition to the parameters which were experimentally investigated, the effect of particle injection velocity was also considered. The simulation results were found to be in good general agreement with the experimental data.

  13. Magnetic Reconnection: A Fundamental Process in Space Plasmas

    NASA Technical Reports Server (NTRS)

    Hesse, Michael

    2010-01-01

    For many years, collisionless magnetic reconnect ion has been recognized as a fundamental process, which facilitates plasma transport and energy release in systems ranging from the astrophysical plasmas to magnetospheres and even laboratory plasma. Beginning with work addressing solar dynamics, it has been understood that reconnection is essential to explain solar eruptions, the interaction of the solar wind with the magnetosphere, and the dynamics of the magnetosphere. Accordingly, the process of magnetic reconnection has been and remains a prime target for space-based and laboratory studies, as well as for theoretical research. Much progress has been made throughout the years, beginning with indirect verifications by studies of processes enabled by reconnection, such as Coronal Mass Ejections, Flux Transfer Events, and Plasmoids. Theoretical advances have accompanied these observations, moving knowledge beyond the Sweet-Parker theory to the recognition that other, collisionless, effects are available and likely to support much faster reconnect ion rates. At the present time we are therefore near a break-through in our understanding of how collisionless reconnect ion works. Theory and modeling have advanced to the point that two competing theories are considered leading candidates for explaining the microphysics of this process. Both theories predict very small spatial and temporal scales. which are. to date, inaccessible to space-based or laboratory measurements. The need to understand magnetic reconnect ion has led NASA to begin the implementation of a tailored mission, Magnetospheric MultiScale (MMS), a four spacecraft cluster equipped to resolve all relevant spatial and temporal scales. In this presentation, we present an overview of current knowledge as well as an outlook towards measurements provided by MMS.

  14. 3. EXTERIOR VIEW, LOOKING EAST, SHOWING QUENCH TOWER, WITH QUENCH ...

    Library of Congress Historic Buildings Survey, Historic Engineering Record, Historic Landscapes Survey

    3. EXTERIOR VIEW, LOOKING EAST, SHOWING QUENCH TOWER, WITH QUENCH IN PROGRESS, WILPUTTE BATTERY, COAL PRE-HEATING UNIT, INCLINE CONVEYOR AND BATHHOUSE. - Alabama By-Products Company, Coke Plant, Highway 79 (Pinson Valley Parkway), Tarrant City, Jefferson County, AL

  15. Prediction of plasma processes using neural network and genetic algorithm

    NASA Astrophysics Data System (ADS)

    Kim, Byungwhan; Bae, Jungki

    2005-10-01

    Using genetic algorithm (GA) and backpropagation neural network (BPNN), computer models of plasma processes were constructed. The GA was applied to optimize five training factors simultaneously. The presented technique was evaluated with plasma etch data, characterized by a statistical experimental design. The etching was conducted in an inductively coupled plasma etch system. The etch outputs to model include aluminum (Al) etch rate, Al selectivity, silica profile angle, and DC bias. GA-BPNN models demonstrated improved predictions of more than 20% for all etch outputs but the DC bias. This indicates that a simultaneous optimization of training factors is more effective in improving the prediction performance of BPNN model than a sequential optimization of individual training factor. Compared to GA-BPNN models constructed in a previous training set, the presented models also yielded a much improved prediction of more than 35% for all etch outputs. The proven improvement indicates that the presented training set is more effective to improve GA-BPNN models.

  16. Plasma processes for producing silanes and derivatives thereof

    DOEpatents

    Laine, Richard M; Massey, Dean Richard; Peterson, Peter Young

    2014-03-25

    The invention is generally related to process for generating one or more molecules having the formula Si.sub.xH.sub.y, Si.sub.xD.sub.y, Si.sub.xH.sub.yD.sub.z, and mixtures thereof, where x,y and z are integers .gtoreq.1, H is hydrogen and D is deuterium, such as silane, comprising the steps of: providing a silicon containing material, wherein the silicon containing material includes at least 20 weight percent silicon atoms based on the total weight of the silicon containing material; generating a plasma capable of vaporizing a silicon atom, sputtering a silicon atom, or both using a plasma generating device; and contacting the plasma to the silicon containing material in a chamber having an atmosphere that includes at least about 0.5 mole percent hydrogen atoms and/or deuterium atoms based on the total moles of atoms in the atmosphere; so that a molecule having the formula Si.sub.xH.sub.y; (e.g., silane) is generated. The process preferably includes a step of removing one or more impurities from the Si.sub.xH.sub.y (e.g., the silane) to form a clean Si.sub.xH.sub.y, Si.sub.xD.sub.y, Si.sub.xH.sub.yD.sub.z (e.g., silane). The process may also include a step of reacting the Si.sub.xH.sub.y, Si.sub.xD.sub.y, Si.sub.xH.sub.yD.sub.z (e.g., the silane) to produce a high purity silicon containing material such as electronic grade metallic silicon, photovoltaic grade metallic silicon, or both.

  17. The processes of nonequilibrium exchange in rotating plasma flows

    NASA Astrophysics Data System (ADS)

    Karimov, A. R.; Shatokhin, V. L.; Yu, M. Y.; Stenflo, L.

    2016-09-01

    The mechanisms of energy/momentum exchange in rotating and compressing plasma flows have been discussed. It has been shown that such flows are capable of transforming the energy of different degrees of freedom into the energy of one degree owing to the interaction of the coupled nonlinear radial, axial and azimuthal electron-ion oscillations. These processes may lead to the additional acceleration of the flow in azimuthal or axial direction so they might be instrumental for the creation of space thrusters employing pulse transformations for propulsion.

  18. Real-Time Plasma Process Condition Sensing and Abnormal Process Detection

    PubMed Central

    Yang, Ryan; Chen, Rongshun

    2010-01-01

    The plasma process is often used in the fabrication of semiconductor wafers. However, due to the lack of real-time etching control, this may result in some unacceptable process performances and thus leads to significant waste and lower wafer yield. In order to maximize the product wafer yield, a timely and accurately process fault or abnormal detection in a plasma reactor is needed. Optical emission spectroscopy (OES) is one of the most frequently used metrologies in in-situ process monitoring. Even though OES has the advantage of non-invasiveness, it is required to provide a huge amount of information. As a result, the data analysis of OES becomes a big challenge. To accomplish real-time detection, this work employed the sigma matching method technique, which is the time series of OES full spectrum intensity. First, the response model of a healthy plasma spectrum was developed. Then, we defined a matching rate as an indictor for comparing the difference between the tested wafers response and the health sigma model. The experimental results showed that this proposal method can detect process faults in real-time, even in plasma etching tools. PMID:22219683

  19. Plasma processing of interstellar PAHs into solar system kerogen

    NASA Technical Reports Server (NTRS)

    Wdowiak, T. J.; Lee, W.; Cronin, J.; Beegle, L. W.; Robinson, M. S.

    1995-01-01

    Processes resulting in the formation of hydrocarbons of carbonaceous chondrites and the identity of the interstellar molecular precursors involved are an objective of investigations into the origin of the solar system and perhaps even life on earth. We have combined the resources and experience of an astronomer and physicists doing laboratory simulations with those of a chemical expert in the analysis of meteoritic hydrocarbons, in a project that investigated the conversion of polycyclic aromatic hydrocarbons (PAHs) formed in stellar atmospheres into alkanes found in meteorites. Plasma hydrogenation has been found in the University of Alabama at Birmingham Astrophysics Laboratory to produce from the precursor PAH naphthalene, a new material having an IR absorption spectrum (Lee, W. and Wdowiak, T.J., Astrophys. J. 417, L49-L51, 1993) remarkably similar to that obtained at Arizona State University of the benzene-methanol extract of the Murchison meteorite (Cronin, J.R. and Pizzarello, S., Geochim. Cosmochim. Acta 54, 2859-2868, 1990). There are astrophysical and meteoritic arguments for PAH species from extra-solar sources being incorporated into the solar nebula, where plasma hydrogenation is highly plausible. Conversion of PAHs into alkanes could also have occurred in the interstellar medium. The synthesis of laboratory analogs of meteoritic hydrocarbons through plasma hydrogenation of PAH species is underway, as is chemical analysis of those analogs. The objective is to clarify this heretofore uninvestigated process and to understand its role during the origin of the solar system as a mechanism of production of hydrocarbon species now found in meteorites. Results have been obtained in the form of time-of-flight spectroscopy and chemical analysis of the lab analog prepared from naphthalene.

  20. Coupled microwave ECR and radio-frequency plasma source for plasma processing

    DOEpatents

    Tsai, C.C.; Haselton, H.H.

    1994-03-08

    In a dual plasma device, the first plasma is a microwave discharge having its own means of plasma initiation and control. The microwave discharge operates at electron cyclotron resonance (ECR), and generates a uniform plasma over a large area of about 1000 cm[sup 2] at low pressures below 0.1 mtorr. The ECR microwave plasma initiates the second plasma, a radio frequency (RF) plasma maintained between parallel plates. The ECR microwave plasma acts as a source of charged particles, supplying copious amounts of a desired charged excited species in uniform manner to the RF plasma. The parallel plate portion of the apparatus includes a magnetic filter with static magnetic field structure that aids the formation of ECR zones in the two plasma regions, and also assists in the RF plasma also operating at electron cyclotron resonance. 4 figures.

  1. Coupled microwave ECR and radio-frequency plasma source for plasma processing

    DOEpatents

    Tsai, Chin-Chi; Haselton, Halsey H.

    1994-01-01

    In a dual plasma device, the first plasma is a microwave discharge having its own means of plasma initiation and control. The microwave discharge operates at electron cyclotron resonance (ECR), and generates a uniform plasma over a large area of about 1000 cm.sup.2 at low pressures below 0.1 mtorr. The ECR microwave plasma initiates the second plasma, a radio frequency (RF) plasma maintained between parallel plates. The ECR microwave plasma acts as a source of charged particles, supplying copious amounts of a desired charged excited species in uniform manner to the RF plasma. The parallel plate portion of the apparatus includes a magnetic filter with static magnetic field structure that aids the formation of ECR zones in the two plasma regions, and also assists in the RF plasma also operating at electron cyclotron resonance.

  2. Results of bench-scale plasma system testing in support of the Plasma Hearth Process

    SciTech Connect

    Leatherman, G.L.; Cornelison, C.; Frank, S.

    1996-10-01

    The Plasma Hearth Process (PHP) is a high-temperature process that destroys hazardous organic components and stabilizes the radioactive components and hazardous metals in a leach-resistant vitreous slag waste form. The PHP technology development program is targeted at mixed waste that cannot be easily treated by conventional means. For example, heterogeneous debris, which may contain hazardous organics, toxic metals, and radionuclides, is difficult to characterize and cannot be treated with conventional thermal, chemical, or physical treatment methods. A major advantage of the PHP over other plasma processes is its ability to separate nonradioactive, non-hazardous metals from the non-metallic and radioactive components which are contained in the vitreous slag. The overall PHP program involves the design, fabrication, and operation of test hardware to demonstrate and certify that the PHP concept is viable for DOE waste treatment. The program involves bench-scale testing of PHP equipment in radioactive service, as well as pilot-scale demonstration of the PHP concept using nonradioactive, surrogate test materials. The fate of secondary waste streams is an important consideration for any technology considered for processing mixed waste. The main secondary waste stream generated by the PHP is flyash captured by the fabric- filter baghouse. The PHP concept is that flyash generated by the process can, to a large extent, be treated by processing this secondary waste stream in the PHP. Prior to the work presented in the paper, however, the PHP project has not quantitatively demonstrated the ability to treat PHP generated flyash. A major consideration is the quantity of radionuclides and RCRA-regulated metals in the flyash that can be retained the resultant waste form.

  3. Optical and electrical diagnostics of fluorocarbon plasma etching processes

    NASA Astrophysics Data System (ADS)

    Booth, Jean-Paul

    1999-05-01

    This article reviews recent work concerning the role of CF and CF2 radicals in etching and polymerization processes occurring in capacitively coupled radio-frequency plasmas in fluorocarbon gases used for the selective etching of SiO2 layers in microelectronic device fabrication. Laser-induced fluorescence (LIF) was used to determine time-resolved axial concentration profiles of these species in continuous and pulse-modulated CF4 and C2F6 plasmas. Calibration techniques, including broad-band UV absorption spectroscopy, were developed to put the LIF measurements on an absolute scale. A novel technique was used to determine the ion flux to the reactor walls in these polymerizing environments. The mass distribution of the ions arriving at the reactor walls was determined using a quadrupole mass spectrometer. It was found that CFx radicals are produced predominantly by the reflection of neutralized and dissociated CFx+ ions at the powered electrode surface. When the fluorine atom concentration is high, the CFx radicals are destroyed effectively by recombination catalysed by the reactor walls. When the fluorine atom concentration is lowered, the CF2 concentration rises markedly, and it participates in gas-phase oligomerization processes, forming large CxFy molecules and, after ionization, large CxFy+ ions. These species appear to be the true polymer precursors. This mechanism explains the well known correlation between high CF2 concentrations, polymer deposition and SiO2 over Si etch selectivity.

  4. Quench studies of ILC cavities

    SciTech Connect

    Eremeev, Grigory; Geng, Rongli; Palczewski, Ari; Dai, Jin

    2011-07-01

    Quench limits accelerating gradient in SRF cavities to a gradient lower than theoretically expected for superconducting niobium. Identification of the quenching site with thermometry and OST, optical inspection, and replica of the culprit is an ongoing effort at Jefferson Lab aimed at better understanding of this limiting phenomenon. In this contribution we present our finding with several SRF cavities that were limited by quench.

  5. Predictive Modeling in Plasma Reactor and Process Design

    NASA Technical Reports Server (NTRS)

    Hash, D. B.; Bose, D.; Govindan, T. R.; Meyyappan, M.; Arnold, James O. (Technical Monitor)

    1997-01-01

    Research continues toward the improvement and increased understanding of high-density plasma tools. Such reactor systems are lauded for their independent control of ion flux and energy enabling high etch rates with low ion damage and for their improved ion velocity anisotropy resulting from thin collisionless sheaths and low neutral pressures. Still, with the transition to 300 mm processing, achieving etch uniformity and high etch rates concurrently may be a formidable task for such large diameter wafers for which computational modeling can play an important role in successful reactor and process design. The inductively coupled plasma (ICP) reactor is the focus of the present investigation. The present work attempts to understand the fundamental physical phenomena of such systems through computational modeling. Simulations will be presented using both computational fluid dynamics (CFD) techniques and the direct simulation Monte Carlo (DSMC) method for argon and chlorine discharges. ICP reactors generally operate at pressures on the order of 1 to 10 mTorr. At such low pressures, rarefaction can be significant to the degree that the constitutive relations used in typical CFD techniques become invalid and a particle simulation must be employed. This work will assess the extent to which CFD can be applied and evaluate the degree to which accuracy is lost in prediction of the phenomenon of interest; i.e., etch rate. If the CFD approach is found reasonably accurate and bench-marked with DSMC and experimental results, it has the potential to serve as a design tool due to the rapid time relative to DSMC. The continuum CFD simulation solves the governing equations for plasma flow using a finite difference technique with an implicit Gauss-Seidel Line Relaxation method for time marching toward a converged solution. The equation set consists of mass conservation for each species, separate energy equations for the electrons and heavy species, and momentum equations for the gas

  6. Analysis of transfer processes through plasma boundaries of the magnetosphere

    NASA Astrophysics Data System (ADS)

    Kozak, Liudmyla; Savin, Sergey; Lui, Anthony Tat Yin; Prokhorenkov, Andrew

    Studying the fundamental properties of the interaction of the solar wind with the magnetosphere found superdiffusion processes in the boundary layers space plasma and 'distant' transfer mechanism (the influence of local microprocesses to global, and vice versa). Since the developed turbulence is characterized by a great number of degrees of freedom, nonlinearly interacting modes, multi-scale structure and random fluctuations of velocities so that the methods of statistical physics and theory of probability are most suitable for its description. In this study based on the mission Cluster measurements the characteristic turbulent regions in the boundary layers of Earth’s magnetosphere are being separated and the statistical characteristics are being obtained, which determine the transfer processes through plasma boundaries. Meanwhile, the set of different techniques was used which are based on the analysis of fluctuation distribution function and its moments. For the analysis of the turbulent processes we have carried out an investigation of structure functions for different orders and studied diffusion processes in different regions determined by a character of the dependence of the generalized diffusion coefficient on time. Basing on the results of studying structural functions of various orders, the conclusion is drawn that small scale turbulence in the foreshock, magnetosheath, turbulent boundary layer is described by different phenomenological models. Besides, we have obtained an increase of diffusion coefficient with time for the regions of magnetosheath. The work is done in the frame of complex program of NAS of Ukraine on space researches for 2012-1016, within the framework of the educational program No.2201250 “Education, Training of students, PhD students, scientific and pedagogical staff abroad” launched by the Ministry of Education and Science of Ukraine and under a partial support of the grant No. F 53.2/039.

  7. A new quenching alternative

    SciTech Connect

    Brennan, R.J.; Faulkner, C.H.

    1996-12-31

    The quenching of ferrous alloys implies the controlled extraction of heat from a part at a rate sufficient to harden the part and still control the desired dimensional limitations. Quenchants in common use today are: molten metals, molten salts, petroleum oils, polymer solutions, water, and salt/water solutions. Each type of quenchant has its benefits and limitations. With current waste legislation and the trends toward environmentally friendlier industrial working fluids, many of these quenching products are coming under close scrutiny by the users and legislators. The most widely used quenchant is petroleum oil due to its favorable heat extraction characteristics. The dependence upon imports, price vulnerability, and contamination potential have caused suppliers and users to look into alternative products. Research into renewable resource, non-petroleum, vegetable oils has been going on globally for several years. The drawbacks encountered with many vegetable oils were widely known and only years of research enabled them to be overcome. The presently formulated product not only performs as well as petroleum oil but shows some characteristics better than those of the petroleum products, especially in the biodegradability and ecological aspects of the products. Stability and reproducible quenching properties have been proven with over two and one half years of field testing.

  8. Plasma analysis for the plasma immersion ion implantation processing by a PIC-MCC simulation

    NASA Astrophysics Data System (ADS)

    Miyagawa, Y.; Ikeyama, M.; Miyagawa, S.; Tanaka, M.; Nakadate, H.

    2007-07-01

    In order to analyze the plasma behavior during PIII processing, a computer simulation has been carried out using the simulation software "PEGASUS". The software uses a Particle-in-Cell (PIC) method for the movement of charged particles in the electromagnetic field and a Monte Carlo method for collisions of ions, electrons, and neutrals in the plasma and also a Monte Carlo method to analyze the background gas behavior for a low density gas system. This approach is based on the weighting collision simulation scheme allowing for disparate number densities of different species. The spatial distributions of potential and densities of ions, electrons and radicals in the coating system were calculated together with the flux of ions and electrons on the surface of the object. The gas pressure was 0.01 to 50 Pa and a negative and/or a positive pulse voltage ( V=0.1 to 20 kV) was applied to the object. The calculation is fully self-consistent. A two-dimensional Cartesian and a cylindrical coordinate system were used. The effects of gas pressure, applied voltage, and secondary electron emission coefficient by ion impact ( γ) on the sheath thickness, the spatial distribution of densities of electron, ion, and neutral atoms, the ion flux and its spatial distribution, etc. were studied for PIII processing of a trench shaped object, inner wall of a pipe and a PET bottle.

  9. Influence of delay step conditions between quenching and aging on the precipitation mechanisms in the alloy AlZnMg AA7028 aging process

    SciTech Connect

    Calatayud, A.; Ferrer, C.; Amigo, V.; Salvador, M.D.

    1997-03-15

    Among precipitation-hardened alloys, the Al-Zn-Mg system includes the aluminium alloys with higher-strength. The relatively high solubility of Zn and Mg in aluminium makes it possible to produce a high density of precipitates, which results in a higher strength increase. AlZnMg low copper or copper free alloys have the advantage of being easily weldable and, moreover, they harden significantly at room temperature with respect to other weldable aluminium alloys. Due to the remarkable degree of natural aging achieved by AA7000 alloys, the time interval at room temperature between quenching and the beginning of the artificial aging treatment is a variable that must be taken into account. This work was undertaken to evaluate the influence of cooling kinetics at quenching on alloy mechanical characteristics in artificial aging at several temperatures T{sub 2}. The effect of variables that define delays after quenching, basically time t{sub 1} and temperature T{sub 1} was also analyzed. Likewise, this work studies microstructural evolution of material exposed to aging treatments, resulting from the combination of the above mentioned variables.

  10. Chemical and physical processes in the retention of functional groups in plasma polymers studied by plasma phase mass spectroscopy.

    PubMed

    Ryssy, Joonas; Prioste-Amaral, Eloni; Assuncao, Daniela F N; Rogers, Nicholas; Kirby, Giles T S; Smith, Louise E; Michelmore, Andrew

    2016-02-14

    Surface engineering of functionalised polymer films is a rapidly expanding field of research with cross disciplinary implications and numerous applications. One method of generating functionalised polymer films is radio frequency induced plasma polymerisation which provides a substrate independent coating. However, there is currently limited understanding surrounding chemical interactions in the plasma phase and physical interactions at the plasma-surface interface, and their effect on functional group retention in the thin film. Here we investigate functionalised plasma polymer films generated from four precursors containing primary amines. Using XPS and fluorine tagging with 4-(trifluoromethyl)benzaldehyde, the primary amine content of plasma polymer films was measured as a function of applied power at constant precursor pressure. The results were then correlated with analysis of the plasma phase by mass spectrometry which showed loss of amine functionality for both neutral and ionic species. Surface interactions are also shown to decrease primary amine retention due to abstraction of hydrogen by high energy ion impacts. The stability of the plasma polymers in aqueous solution was also assessed and is shown to be precursor dependent. Increased understanding of the chemical and physical processes in the plasma phase and at the surface are therefore critical in designing improved plasma polymerisation processes. PMID:26791435

  11. Secondary electron emission from plasma processed accelerating cavity grade niobium

    NASA Astrophysics Data System (ADS)

    Basovic, Milos

    by different techniques. Specifically, this work provides the results of SEY from the plasma cleaned cavity grade niobium (Nb) samples. Pure niobium is currently the material of choice for the fabrication of Superconducting Radio Frequency (SRF) cavities. The effect of plasma processing with two different gases will be examined in two groups of samples. The first group of samples is made from cavity grade niobium. The second group of samples is made from the same material, but include a welded joint made by electron beam welding, since in niobium SRF cavities the peak electric and magnetic field are seen in close proximity to the welded joints. Both groups of samples will be exposed to nitrogen (N2) and a mixture of argon with oxygen (Ar/O2) plasma. It is the goal of this research to determine the SEY on these two groups of samples before and after plasma processing as a function of the energy of primary electrons. The SEY as a function of the angle of incidence of the primary electrons is tested on the samples treated with Ar/O2 plasma.

  12. Nonlinear transport processes in tokamak plasmas. I. The collisional regimes

    SciTech Connect

    Sonnino, Giorgio; Peeters, Philippe

    2008-06-15

    An application of the thermodynamic field theory (TFT) to transport processes in L-mode tokamak plasmas is presented. The nonlinear corrections to the linear ('Onsager') transport coefficients in the collisional regimes are derived. A quite encouraging result is the appearance of an asymmetry between the Pfirsch-Schlueter (P-S) ion and electron transport coefficients: the latter presents a nonlinear correction, which is absent for the ions, and makes the radial electron coefficients much larger than the former. Explicit calculations and comparisons between the neoclassical results and the TFT predictions for Joint European Torus (JET) plasmas are also reported. It is found that the nonlinear electron P-S transport coefficients exceed the values provided by neoclassical theory by a factor that may be of the order 10{sup 2}. The nonlinear classical coefficients exceed the neoclassical ones by a factor that may be of order 2. For JET, the discrepancy between experimental and theoretical results for the electron losses is therefore significantly reduced by a factor 10{sup 2} when the nonlinear contributions are duly taken into account but, there is still a factor of 10{sup 2} to be explained. This is most likely due to turbulence. The expressions of the ion transport coefficients, determined by the neoclassical theory in these two regimes, remain unaltered. The low-collisional regimes, i.e., the plateau and the banana regimes, are analyzed in the second part of this work.

  13. Process maps for plasma spray. Part II: Deposition and properties

    SciTech Connect

    XIANGYANG,JIANG; MATEJICEK,JIRI; KULKARNI,ANAND; HERMAN,HERBERT; SAMPATH,SANJAY; GILMORE,DELWYN L.; NEISER JR.,RICHARD A

    2000-03-28

    This is the second paper of a two part series based on an integrated study carried out at the State University of New York at Stony Brook and Sandia National Laboratories. The goal of the study is the fundamental understanding of the plasma-particle interaction, droplet/substrate interaction, deposit formation dynamics and microstructure development as well as the deposit property. The outcome is science-based relationships, which can be used to link processing to performance. Molybdenum splats and coatings produced at 3 plasma conditions and three substrate temperatures were characterized. It was found that there is a strong mechanical/thermal interaction between droplet and substrate, which builds up the coatings/substrate adhesion. Hardness, thermal conductivity, and modulus increase, while oxygen content and porosity decrease with increasing particle velocity. Increasing deposition temperature resulted in dramatic improvement in coating thermal conductivity and hardness as well as increase in coating oxygen content. Indentation reveals improved fracture resistance for the coatings prepared at higher deposition temperature. Residual stress was significantly affected by deposition temperature, although not significant by particle energy within the investigated parameter range. Coatings prepared at high deposition temperature with high-energy particles suffered considerably less damage in wear tests. Possible mechanisms behind these changes are discussed within the context of relational maps which are under development.

  14. Measuring DNA through a Nanopore Fabricated Using Plasma Processing Technology

    NASA Astrophysics Data System (ADS)

    Rossnagel, S. M.

    2009-10-01

    We have been developing a device based on a 2-3 nm diameter pore between two electrolyte volumes for the transit of DNA by means of a potential gradient. The nanopore is configured with 3 electrodes, each about 3 nm thick with 2-3nm dielectric spacers. The nanopore electrodes can be used to trap DNA in-transit, and ideally measure the impedance and hence the identity of each nucleotide as it passes through the nanopore, allowing real time sequencing of the DNA. The goal is to operate at megahertz, allowing sequencing of the entire genome within a few hours a fairly modest cost. This project has lead to numerous new developments in nanoscale fabrication, particularly for nanofluidics. The nanopore devices are fabricated using a number of critical plasma processing steps, both deposition and etch, in our 200mm pilot facility.

  15. Experimental methods for quenching structures in lunar-analog silicate melts - Variations as a function of quench media and composition

    NASA Astrophysics Data System (ADS)

    Dybar, M. D.

    1984-11-01

    Compositions analogous to lunar green, orange, and brown glasses were synthesized under consistent conditions, then quenched into a variety of different media when the samples were removed from the furnace. Iron valence and coordination are a direct function of quench media used, spanning the range from brine/ice (most effective quench), water, butyl phthalate, silicone oil, liquid nitrogen, highly reducing CO-CO2 gas, to air (least efficient quench). In the green and brown glasses, Fe(3+) in four-fold and six-fold coordination is observed in the slowest-quenched samples; Fe(2+) coordination varies directly with quench efficiency. Less pronounced changes were observed in the Ti-rich orange glass. Therefore the remote-sensed spectrum of a glass-bearing regolith on the moon may be influenced by the process by which the glass cooled, and extreme caution must be used when comparing spectra of synthetic glass analogs with real lunar glasses.

  16. Experimental methods for quenching structures in lunar-analog silicate melts - Variations as a function of quench media and composition

    NASA Technical Reports Server (NTRS)

    Dyar, M. D.

    1984-01-01

    Compositions analogous to lunar green, orange, and brown glasses were synthesized under consistent conditions, then quenched into a variety of different media when the samples were removed from the furnace. Iron valence and coordination are a direct function of quench media used, spanning the range from brine/ice (most effective quench), water, butyl phthalate, silicone oil, liquid nitrogen, highly reducing CO-CO2 gas, to air (least efficient quench). In the green and brown glasses, Fe(3+) in four-fold and six-fold coordination is observed in the slowest-quenched samples; Fe(2+) coordination varies directly with quench efficiency. Less pronounced changes were observed in the Ti-rich orange glass. Therefore the remote-sensed spectrum of a glass-bearing regolith on the moon may be influenced by the process by which the glass cooled, and extreme caution must be used when comparing spectra of synthetic glass analogs with real lunar glasses.

  17. Experimental methods for quenching structures in lunar-analog silicate melts: Variations as a function of quench media and composition

    NASA Technical Reports Server (NTRS)

    Dyar, M. D.

    1985-01-01

    Compositions analogous to lunar green, organge, and brown glasses were synthesized under consistent conditions, then quenched into a variety of different media when the samples were removed from the furnace. Iron valence and coordination are a direct function of quench media used, spanning the range from brine/ice (most effective quench), water, butyl phthalate, silicone oil, liquid nitrogen, highly reducing CO-CO2 gas, to air (least efficient quench). In the green and brown glasses, Fe(3+) in four-fold and six-fold coordination is observed in the slowest-quenched samples; Fe(2+) coordination varies directly with quench efficiency. Less pronounced changes were observed in the Ti-rich orange glass. Therefore the remote-sensed spectrum of a glass-bearing regolith on the Moon may be influenced by the process by which the glass cooled, and extreme caution must be used when comparing spectra of synthetic glass analogs with real lunar glasses.

  18. The Plasma Hearth Process demonstration project for mixed waste treatment

    SciTech Connect

    Geimer, R.; Dwight, C.; McClellan, G.

    1994-07-01

    The Plasma Hearth Process (PHP) demonstration project is one of the key technology projects in the Department of Energy (DOE) Office of Technology Development (OTD) Mixed Waste Integrated Program (MWIP). Testing to date has yielded encouraging results in displaying potential applications for the PHP technology. Early tests have shown that a wide range of waste materials can be readily processed in the PHP and converted to a vitreous product. Waste materials can be treated in their original container as received at the treatment facility, without pretreatment. The vitreous product, when cooled, exhibits excellent performance in leach resistance, consistently exceeding the Environmental Protection Agency (EPA) Toxicity Characteristic Leaching Procedure (TCLP) requirements. Performance of the Demonstration System during test operations has been shown to meet emission requirements. An accelerated development phase, being conducted at both bench- and pilot-scale on both nonradioactive and radioactive materials, will confirm the viability of the process. It is anticipated that, as a result of this accelerated technology development and demonstration phase, the PHP will be ready for a final field-level demonstration within three years.

  19. Dynamical properties of non-equilibrium atmospheric plasma jets and their applications to plasma processing in liquids

    NASA Astrophysics Data System (ADS)

    Kitano, Katsuhisa; Satoshi, Ikawa; Furusho, Hitoshi; Nagasaki, Yukio; Hamaguchi, Satoshi

    2007-11-01

    Non-equilibrium atmospheric pressure plasma jets are discussed with the emphasis on their physics and applications. Plume-like plasmas, which may be called plasma jets, have been generated in a discharge system consisting of a dielectric/metal tube (through which He gas flows at the atmospheric pressure) and a single electrode attached to the tube, to which low-frequency, high-voltage pulses (˜10kV, ˜10kHz) are applied. With visible light images taken by a high-speed ICCD camera, it has been confirmed that the plasma jet consists of a series of small ``plasma bullets'' that are emitted intermittently from the powered electrode in sync with the positive voltage pulses. The observed ``plasma bullet'' may be interpreted as a fast moving ionization front. The plasma jets are energetic enough to generate highly reactive charge-neutral radicals but their gas temperatures remain low. Therefore the plasma jets are ideal for processing of liquid based materials at low temperatures and some examples of process applications, such as reduction of cations, polymerization of liquid monomers, and sterilization, will be also presented.

  20. Dynamical quenching of tunneling in molecular magnets

    NASA Astrophysics Data System (ADS)

    José Santander, María; Nunez, Alvaro S.; Roldán-Molina, A.; Troncoso, Roberto E.

    2015-12-01

    It is shown that a single molecular magnet placed in a rapidly oscillating magnetic field displays the phenomenon of quenching of tunneling processes. The results open a way to manipulate the quantum states of molecular magnets by means of radiation in the terahertz range. Our analysis separates the time evolution into slow and fast components thereby obtaining an effective theory for the slow dynamics. This effective theory presents quenching of the tunnel effect, in particular, stands out its difference with the so-called coherent destruction of tunneling. We support our prediction with numerical evidence based on an exact solution of Schrödinger's equation.

  1. Thermal compression chip interconnection using organic solderability preservative etched substrate by plasma processing.

    PubMed

    Cho, Sung-Won; Choi, JoonYoung; Chung, Chin-Wook

    2014-12-01

    The solderability of copper organic solderbility preservative (CuOSP) finished substrate was enhanced by the plasma etching. To improve the solderability of TC interconnection with the CuOSP finished substrate, the plasma etching process is used. An Oxygen-Hydrogen plasma treatment process is performed to remove OSP material. To prevent the oxidation by oxygen plasma treatment, hydrogen reducing process is also performed before TC interconnection process. The thickness of OSP material after plasma etching is measured by optical reflection method and the component analysis by Auger Electron Spectroscopy is performed. From the lowered thickness, the bonding force of TC interconnection after OSP etching process is lowered. Also the electrical open/short test was performed after assembling the completed semiconductor packaging. The improved yield due to the plasma etching process is achieved.

  2. Quench Module Insert Capabilities and Development Test Results

    NASA Technical Reports Server (NTRS)

    Carswell, B.; Crouch, M.; Farmer, J.; Breeding, S.; Rose, F.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    Quench Module Insert is a directional solidification furnace, which will fly in the Materials Science Research Facility. The QMI provides high thermal gradient and quench capabilities for processing metals and alloys in microgravity. This paper will describe the capabilities and present of on-going analysis and development testing.

  3. Production of stable isotopes utilizing the plasma separation process

    NASA Astrophysics Data System (ADS)

    Bigelow, T. S.; Tarallo, F. J.; Stevenson, N. R.

    2005-12-01

    A plasma separation process (PSP) is being operated at Theragenics Corporation's®, Oak Ridge, TN, facility for the enrichment of stable isotopes. The PSP utilizes ion cyclotron mass discrimination to separate isotopes on a relatively large scale. With a few exceptions, nearly any metallic element could be processed with PSP. Output isotope enrichment factor depends on natural abundance and mass separation and can be fairly high in some cases. The Theragenics™ PSP facility is believed to be the only such process currently in operation. This system was developed and formerly operated under the US Department of Energy Advanced Isotope Separation program. Theragenics™ also has a laboratory at the PSP site capable of harvesting the isotopes from the process and a mass spectrometer system for analyzing enrichment and product purity. Since becoming operational in 2002, Theragenics™ has utilized the PSP to separate isotopes of several elements including: dysprosium, erbium, gadolinium, molybdenum and nickel. Currently, Theragenics™ is using the PSP for the separation of 102Pd, which is used as precursor for the production of 103Pd. The 103Pd radioisotope is the active ingredient in TheraSeed®, which is used in the treatment of early stage prostate cancer and being investigated for other medical applications. New industrial, medical and research applications are being investigated for isotopes that can be enriched on the PSP. Pre-enrichment of accelerator or reactor targets offers improved radioisotope production. Theragenics operates 14 cyclotrons for proton activation and has access to HFIR at ORNL for neutron activation of radioisotopes.

  4. Simultaneous monitoring of multimetallic atom densities in plasma processes employing a multimicrohollow cathode lamp

    SciTech Connect

    Ohta, Takayuki; Ito, Masafumi; Tachibana, Yoshihiro; Taneda, Satoshi; Takashima, Seigo; Hori, Masaru; Kano, Hiroyuki; Den, Shoji

    2007-06-18

    The authors have developed a simultaneous measurement technique of multimetallic atom densities in process plasmas using absorption spectroscopy employing a multimicrohollow cathode plasma as a light source. The optical emissions of four metallic atoms of Cu, Zn, Fe, and Mo were simultaneously produced from the multimicrohollow cathode plasma of millimeter size. The absolute densities of Cu and Mo in the magnetron sputtering plasma were simultaneously measured using this technique. The simultaneous monitoring of multimetallic atoms is very useful for controlling the plasma processes precisely.

  5. Small size plasma tools for material processing at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Ionita, E. R.; Ionita, M. D.; Stancu, E. C.; Teodorescu, M.; Dinescu, G.

    2009-03-01

    A small size radiofrequency plasma jet source able to produce cold plasma jets at atmospheric pressure is presented. The surface modification of polyethylene terephtalate, polyethylene and polytetrafluorethylene foils is performed by using a scanning procedure. The contact angle measurements reveal that the treatment leads to hydrophilicity increase. The roughening of surface, specific to each material is noticed. A significant improvement of adhesion is obtained as result of atmospheric plasma treatments.

  6. In-situ plasma processing to increase the accelerating gradients of SRF cavities

    DOE PAGESBeta

    Doleans, Marc; Afanador, Ralph; Barnhart, Debra L.; Degraff, Brian D.; Gold, Steven W.; Hannah, Brian S.; Howell, Matthew P.; Kim, Sang-Ho; Mammosser, John; McMahan, Christopher J.; et al

    2015-12-31

    A new in-situ plasma processing technique is being developed at the Spallation Neutron Source (SNS) to improve the performance of the cavities in operation. The technique utilizes a low-density reactive oxygen plasma at room temperature to remove top surface hydrocarbons. The plasma processing technique increases the work function of the cavity surface and reduces the overall amount of vacuum and electron activity during cavity operation; in particular it increases the field emission onset, which enables cavity operation at higher accelerating gradients. Experimental evidence also suggests that the SEY of the Nb surface decreases after plasma processing which helps mitigating multipactingmore » issues. This article discusses the main developments and results from the plasma processing R&D are presented and experimental results for in-situ plasma processing of dressed cavities in the SNS horizontal test apparatus.« less

  7. In-situ plasma processing to increase the accelerating gradients of superconducting radio-frequency cavities

    NASA Astrophysics Data System (ADS)

    Doleans, M.; Tyagi, P. V.; Afanador, R.; McMahan, C. J.; Ball, J. A.; Barnhart, D. L.; Blokland, W.; Crofford, M. T.; Degraff, B. D.; Gold, S. W.; Hannah, B. S.; Howell, M. P.; Kim, S.-H.; Lee, S.-W.; Mammosser, J.; Neustadt, T. S.; Saunders, J. W.; Stewart, S.; Strong, W. H.; Vandygriff, D. J.; Vandygriff, D. M.

    2016-03-01

    A new in-situ plasma processing technique is being developed at the Spallation Neutron Source (SNS) to improve the performance of the cavities in operation. The technique utilizes a low-density reactive oxygen plasma at room temperature to remove top surface hydrocarbons. The plasma processing technique increases the work function of the cavity surface and reduces the overall amount of vacuum and electron activity during cavity operation; in particular it increases the field emission onset, which enables cavity operation at higher accelerating gradients. Experimental evidence also suggests that the SEY of the Nb surface decreases after plasma processing which helps mitigating multipacting issues. In this article, the main developments and results from the plasma processing R&D are presented and experimental results for in-situ plasma processing of dressed cavities in the SNS horizontal test apparatus are discussed.

  8. In-situ plasma processing to increase the accelerating gradients of SRF cavities

    SciTech Connect

    Doleans, Marc; Afanador, Ralph; Barnhart, Debra L.; Degraff, Brian D.; Gold, Steven W.; Hannah, Brian S.; Howell, Matthew P.; Kim, Sang-Ho; Mammosser, John; McMahan, Christopher J.; Neustadt, Thomas S.; Saunders, Jeffrey W.; Tyagi, Puneet V.; Vandygriff, Daniel J.; Vandygriff, David M.; Ball, Jeffrey Allen; Blokland, Willem; Crofford, Mark T.; Lee, Sung-Woo; Stewart, Stephen; Strong, William Herb

    2015-12-31

    A new in-situ plasma processing technique is being developed at the Spallation Neutron Source (SNS) to improve the performance of the cavities in operation. The technique utilizes a low-density reactive oxygen plasma at room temperature to remove top surface hydrocarbons. The plasma processing technique increases the work function of the cavity surface and reduces the overall amount of vacuum and electron activity during cavity operation; in particular it increases the field emission onset, which enables cavity operation at higher accelerating gradients. Experimental evidence also suggests that the SEY of the Nb surface decreases after plasma processing which helps mitigating multipacting issues. This article discusses the main developments and results from the plasma processing R&D are presented and experimental results for in-situ plasma processing of dressed cavities in the SNS horizontal test apparatus.

  9. The Role of Quench-back in the Passive Quench Protection of Long Solenoids with Coil Sub-division

    SciTech Connect

    Green, Michael A.; Guo, XingLong; Wang, Li; Pan, Heng; Wu, Hong

    2009-10-19

    This paper describes how a passive quench protection system can be applied to long superconducting solenoid magnets. When a solenoid coil is long compared to its thickness, the magnet quench process will be dominated by the time needed for uench propagation along the magnet length. Quench-back will permit a long magnet to quench more rapidly in a passive way. Quenchback from a conductive (low resistivity) mandrel is essential for spreading the quench along the length of a magnet. The andrel must be inductively coupled to the magnet circuit that is being quenched. Current induced in the mandrel by di/dt in the magnet produces heat in the mandrel, which in turn causes the superconducting coil wound on the mandrel to quench. Sub-divisions often employed to reduce the voltages to ground within the coil. This paper explores when it is possible for quench-back to be employed for passive quench protection. The role of sub-division of the coil is discussed for long magnets.

  10. On the possibility of the multiple inductively coupled plasma and helicon plasma sources for large-area processes

    SciTech Connect

    Lee, Jin-Won; Lee, Yun-Seong Chang, Hong-Young; An, Sang-Hyuk

    2014-08-15

    In this study, we attempted to determine the possibility of multiple inductively coupled plasma (ICP) and helicon plasma sources for large-area processes. Experiments were performed with the one and two coils to measure plasma and electrical parameters, and a circuit simulation was performed to measure the current at each coil in the 2-coil experiment. Based on the result, we could determine the possibility of multiple ICP sources due to a direct change of impedance due to current and saturation of impedance due to the skin-depth effect. However, a helicon plasma source is difficult to adapt to the multiple sources due to the consistent change of real impedance due to mode transition and the low uniformity of the B-field confinement. As a result, it is expected that ICP can be adapted to multiple sources for large-area processes.

  11. On the possibility of the multiple inductively coupled plasma and helicon plasma sources for large-area processes

    NASA Astrophysics Data System (ADS)

    Lee, Jin-Won; Lee, Yun-Seong; Chang, Hong-Young; An, Sang-Hyuk

    2014-08-01

    In this study, we attempted to determine the possibility of multiple inductively coupled plasma (ICP) and helicon plasma sources for large-area processes. Experiments were performed with the one and two coils to measure plasma and electrical parameters, and a circuit simulation was performed to measure the current at each coil in the 2-coil experiment. Based on the result, we could determine the possibility of multiple ICP sources due to a direct change of impedance due to current and saturation of impedance due to the skin-depth effect. However, a helicon plasma source is difficult to adapt to the multiple sources due to the consistent change of real impedance due to mode transition and the low uniformity of the B-field confinement. As a result, it is expected that ICP can be adapted to multiple sources for large-area processes.

  12. Feedback control of chlorine inductively coupled plasma etch processing

    SciTech Connect

    Lin Chaung; Leou, K.-C.; Shiao, K.-M.

    2005-03-01

    Feedback control has been applied to poly-Si etch processing using a chlorine inductively coupled plasma. Since the positive ion flux and ion energy incident upon the wafer surface are the key factors that influence the etch rate, the ion current and the root mean square (rms) rf voltage on the wafer stage, which are measured using an impedance meter connected to the wafer stage, are adopted as the controlled variables to enhance etch rate. The actuators are two 13.56 MHz rf power generators, which adjust ion density and ion energy, respectively. The results of closed-loop control show that the advantages of feedback control can be achieved. For example, with feedback control, etch rate variation under the transient chamber wall condition is reduced roughly by a factor of 2 as compared to the open-loop case. In addition, the capability of the disturbance rejection was also investigated. For a gas pressure variation of 20%, the largest etch rate variation is about 2.4% with closed-loop control as compared with as large as about 6% variation using open-loop control. Also the effect of ion current and rms rf voltage on etch rate was studied using 2{sup 2} factorial design whose results were used to derive a model equation. The obtained formula was used to adjust the set point of ion current and rf voltage so that the desired etch rate was obtained.

  13. Magnetic filter apparatus and method for generating cold plasma in semicoductor processing

    DOEpatents

    Vella, Michael C.

    1996-01-01

    Disclosed herein is a system and method for providing a plasma flood having a low electron temperature to a semiconductor target region during an ion implantation process. The plasma generator providing the plasma is coupled to a magnetic filter which allows ions and low energy electrons to pass therethrough while retaining captive the primary or high energy electrons. The ions and low energy electrons form a "cold plasma" which is diffused in the region of the process surface while the ion implantation process takes place.

  14. Magnetic filter apparatus and method for generating cold plasma in semiconductor processing

    DOEpatents

    Vella, M.C.

    1996-08-13

    Disclosed herein is a system and method for providing a plasma flood having a low electron temperature to a semiconductor target region during an ion implantation process. The plasma generator providing the plasma is coupled to a magnetic filter which allows ions and low energy electrons to pass therethrough while retaining captive the primary or high energy electrons. The ions and low energy electrons form a ``cold plasma`` which is diffused in the region of the process surface while the ion implantation process takes place. 15 figs.

  15. Thermal plasma processing of materials. Progress report, September 1, 1988--January 31, 1992

    SciTech Connect

    Pfender, E.; Heberlein, J.

    1992-02-01

    Emphasis has been on plasma synthesis of fine powders, plasma Chemical Vapor Deposition (CVD), on related diagnostics, and on modeling work. Since plasma synthesis as well as plasma CVD make frequent use of plasma jets, the beginning has been devoted of plasma jets and behavior of particulates injected into such plasma jets. Although most of the construction of the Triple-Torch Plasma Reactor (TTPR) has already been done, modifications have been made in particular modifications required for plasma CVD of diamond. A new reactor designed for Counter-Flow Liquid Injection Plasma Synthesis (CFLIPS) proved to be an excellent tool for synthesis of fine powders as well as for plasma CVD. An attempt was made to model flow and temperature fields in this reactor. Substantial efforts were made to single out those parameters which govern particle size, size distribution, and powder quality in our plasma synthesis experiments. This knowledge is crucial for controlling the process and for meaningful diagnostics and modeling work. Plasma CVD of diamond films using both reactors has been very successful and we have been approached by a number of companies interested in using this technology for coating of tools.

  16. On uniform plasma generation for the large area plasma processing in intermediate pressures

    SciTech Connect

    Kim, Hyun Jun; Hwang, Hye-Ju; Cho, Jeong Hee; Chae, Hee Sun; Kim, Dong Hwan; Chung, Chin-Wook

    2015-04-21

    Radial plasma discharge characteristics in the range of 450 mm were studied in a dual inductively coupled plasma (ICP) source, which consisted of a helical ICP and the side type ferrite ICPs. Since the energy relaxation length is shorter than the distance between each of the ferrite ICPs in an intermediate pressure (600 mTorr), local difference in the plasma ignition along the antenna position were observed. In addition, large voltage drop in the discharge of the ferrite ICPs causes an increase in the displacement current to the plasma, and separate discharge mode (E and H mode) according to the antenna position was observed. This results in non-uniform plasma distribution. For the improvement in the discharge of the ferrite ICPs, a capacitor which is placed between the ends of antenna and the ground is adjusted to minimize the displacement current to the plasma. As a result, coincident transitions from E to H mode were observed along the antenna position, and radially concave density profile (edge focused) was measured. For the uniform density distribution, a helical ICP, which located at the center of the discharge chamber, was simultaneously discharged with the ferrite ICPs. Due to the plasma potential variation through the simultaneous discharge of helical ICP and ferrite ICPs, uniform radial distribution in both plasma density and electron temperature are achieved.

  17. On uniform plasma generation for the large area plasma processing in intermediate pressures

    NASA Astrophysics Data System (ADS)

    Kim, Hyun Jun; Hwang, Hye-Ju; Kim, Dong Hwan; Cho, Jeong Hee; Chae, Hee Sun; Chung, Chin-Wook

    2015-04-01

    Radial plasma discharge characteristics in the range of 450 mm were studied in a dual inductively coupled plasma (ICP) source, which consisted of a helical ICP and the side type ferrite ICPs. Since the energy relaxation length is shorter than the distance between each of the ferrite ICPs in an intermediate pressure (600 mTorr), local difference in the plasma ignition along the antenna position were observed. In addition, large voltage drop in the discharge of the ferrite ICPs causes an increase in the displacement current to the plasma, and separate discharge mode (E and H mode) according to the antenna position was observed. This results in non-uniform plasma distribution. For the improvement in the discharge of the ferrite ICPs, a capacitor which is placed between the ends of antenna and the ground is adjusted to minimize the displacement current to the plasma. As a result, coincident transitions from E to H mode were observed along the antenna position, and radially concave density profile (edge focused) was measured. For the uniform density distribution, a helical ICP, which located at the center of the discharge chamber, was simultaneously discharged with the ferrite ICPs. Due to the plasma potential variation through the simultaneous discharge of helical ICP and ferrite ICPs, uniform radial distribution in both plasma density and electron temperature are achieved.

  18. Plasma Interaction with Organic Molecules in Liquid as Fundamental Processes in Plasma Medicine.

    PubMed

    Takenaka, Kosuke; Miyazaki, Atsushi; Abe, Hiroya; Uchida, Giichiro; Setsuhara, Yuichi

    2015-03-01

    Investigation of plasma-organic materials interaction in aqueous solution with atmospheric pressure plasmas have been carried out. Degradation of methylene blue (MB) in aqueous solution via atmospheric pressure He plasma exposure through gas/liquid interface have been investigated. The optical emission spectrum shows considerable emissions of He lines and the emission of O, OH and N radicals attributed to dissociation of water (H2O) and air has been confirmed. Structure variation of MB in solution treated with the atmospheric-pressure He plasma has been measured by Fourier transform infrared spectroscopy (FT-IR). The results obtained from FT-IR analysis show degradation of MB in solution treated with the atmospheric-pressure He plasma. The pH effect of MB degradation was investigated using controlled pH solutions by an ultraviolet-visible (UV-Vis) spectroscopy and FT-IR. The results show no effect of MB degradation on pH. The results exhibit that the atmospheric pressure plasmas exposure has made it possible to degrade organic materials in solution due to irradiated radicals from plasma through plasma/liquid interface. PMID:26413629

  19. Organic synthesis by quench reactions.

    PubMed

    Park, W K; Hochstim, A R

    1975-01-01

    The effects of chemical quench reactions on the formation of organic compounds at a water surface under simulated primordial earth conditions were investigated for the study of chemical evolution. A mixture of gaseous methane and ammonia over a water surface was exposed to an arc discharge between an electrode and the water surface. This discharge served as a source of dissociated, ionized and excited atomic and molecular species. Various organic molecules were formed in the gaseous, aqueous, and solid states by a subsequent quenching of these reactive species on the water surface. The effects of these water-surface quench reactions were assessed by comparing the amounts of synthesized molecules to the amounts which formed during the discharge of an arc above the water level. The results showed that: (1) the water-surface quench reaction permitted faster rates of formation of an insoluble solid and (2) the quench discharge yielded twice as much amino acids and 17 times more insoluble solids by weight than the other discharge. The highest yield of amino acids with the quench reaction was 9 x 10-7 molecules per erg of input energy. These observations indicate that quench reactions on the oceans, rain, and clouds that would have followed excitation by lightning and shock waves may have played an important role in the prebiotic milieu. Furthermore, the possibility exists that quench reactions can be exploited for the synthesis of organic compounds on a larger scale from simple starting materials.

  20. Quench Crucibles Reinforced with Metal

    NASA Technical Reports Server (NTRS)

    Holmes, Richard R.; Carrasquillo, Edgar; O'Dell, J. Scott; McKehnie, N.

    2008-01-01

    Improved crucibles consisting mainly of metal-reinforced ceramic ampules have been developed for use in experiments in which material specimens are heated in the crucibles to various high temperatures, then quenched by, for example, plunging the crucibles into water at room temperature. In a traditional quench crucible, the gap between the ampule and the metal cartridge impedes the transfer of heat to such a degree that the quench rate (the rate of cooling of the specimen) can be too low to produce the desired effect in the specimen. One can increase the quench rate by eliminating the metal cartridge to enable direct quenching of the ampule, but then the thermal shock of direct quenching causes cracking of the ampule. In a quench crucible of the present improved type, there is no gap and no metal cartridge in the traditional sense. Instead, there is an overlay of metal in direct contact with the ampule, as shown on the right side of the figure. Because there is no gap between the metal overlay and the ampule, the heat-transfer rate can be much greater than it is in a traditional quench crucible. The metal overlay also reinforces the ampule against cracking.

  1. Particle contamination control in plasma processing: Building-in reliability for semiconductor fabrication

    SciTech Connect

    Selwyn, G.S.

    1995-12-31

    Plasma processing is used for {approximately}35% of the process steps required for semiconductor manufacturing. Recent studies have shown that plasma processes create the greatest amount of contaminant dust of all the manufacturing steps required for device fabrication. Often, the level of dust in a plasma process tool exceeds the cleanroom by several orders of magnitude. Particulate contamination generated in a plasma tool can result in reliability problems as well as device failure. Inter-level wiring shorts different levels of metallization on a device is a common result of plasma particulate contamination. We have conducted a thorough study of the physics and chemistry involved in particulate formation and transport in plasma tools. In-situ laser light scattering (LLS) is used for real-time detection of the contaminant dust. The results of this work are highly surprising: all plasmas create dust; the dust can be formed by homogeneous as well as heterogeneous chemistry; this dust is charged and suspended in the plasma; additionally, it is transported to favored regions of the plasma, such as those regions immediately above wafers. Fortunately, this work has also led to a novel means of controlling and eliminating these unwanted contaminants: electrostatic {open_quotes}drainpipes{close_quotes} engineered into the electrode by means of specially designed grooves. These channel the suspended particles out of the plasma and into the pump port before they can fall onto the wafer.

  2. Ionization Properties of Molecules Commonly Used for Plasma Processing of Semi-Conductors

    NASA Technical Reports Server (NTRS)

    Srivastava, S. K.

    2000-01-01

    Two types of processes are involved in plasma processing of semi-conductors. They are: plasma etching or cleaning and plasma deposition of the semi-conducting materials. For plasma etching of semi-conductors mostly halogen containing gases are used as additives to gases such as O2 and N2. For plasma deposition gases such as C2H2, SiH4, Si2H6 have been tested in the past. For an optimal performance of a reactor it is important to model the plasma. In this modeling effort electron impact excitation and ionization cross sections play a central role. For ionization balance calculations values of ionization cross sections are needed. Ion molecule reactions determine the ultimate composition of the plasma. Recently it has been discovered that the by products of many of these plasmas are per fluro hydrocarbons (PFCs) which are highly infrared absorbing species and have long life times in the atmosphere. They cause global warming. A lot of research is being pursued at the present time to find alternative molecules which do not produce global warming gases as the and product of the plasma processing reactor. There is also interest in the ionization and dissociative ionization properties of these molecules from the point view of the plasma abatement of the pollutant gases at the exhaust of the semi-conductor processing reactors. At the conference ionization and dissociative ionization properties of some of these molecules will be presented.

  3. LHC magnet quench protection system

    NASA Astrophysics Data System (ADS)

    Coull, L.; Hagedorn, D.; Remondino, V.; Rodriguez-Mateos, F.

    1994-07-01

    The quench protection system for the superconducting magnets of the CERN Large Hadron Collider (LHC) is described. The system is based on the so called 'cold diode' concept. In a group of series connected magnets if one magnet quenches then the magnetic energy of all the magnets will be dissipated in the quenched magnet so destroying it. This is avoided by by-passing the quenched magnet and then rapidly de-exciting the unquenched magnets. For the LHC machine it is foreseen to use silicon diodes situated inside the cryostat as by-pass elements - so called 'cold diodes'. The diodes are exposed to some 50 kGray of radiation during a 10 year operation life-time. The high energy density of the LHC magnets (500 kJ/m) coupled with the relatively slow propagation speed of a 'natural' quench (10 to 20 m/s) can lead to excessive heating of the zone where the quench started and to high internal voltages. It is therefore necessary to detect quickly the incipient quench and fire strip heaters which spread the quench out more quickly over a large volume of the magnet. After a quench the magnet chain must be de-excited rapidly to avoid spreading the quench to other magnets and over-heating the by-pass diode. This is done by switching high-power energy-dump resistors in series with the magnets. The LHC main ring magnet will be divided into 16 electrically separated units which has important advantages.

  4. Air plasma processing of poly(methyl methacrylate) micro-beads: Surface characterisations

    NASA Astrophysics Data System (ADS)

    Liu, Chaozong; Cui, Nai-Yi; Osbeck, Susan; Liang, He

    2012-10-01

    This paper reports the surface processing of poly(methyl methacrylate) (PMMA) micro-beads by using a rotary air plasma reactor, and its effects on surface properties. The surface properties, including surface wettability, surface chemistry and textures of the PMMA beads, were characterised. It was observed that the air plasma processing can improve the surface wettability of the PMMA microbeads significantly. A 15 min plasma processing can reduce the surface water contact angle of PMMA beads to about 50° from its original value of 80.3°. This was accompanied by about 8% increase in surface oxygen concentration as confirmed by XPS analysis. The optical profilometry examination revealed the air plasma processing resulted in a rougher surface that has a “delicate” surface texture. It is concluded that the surface chemistry and texture, induced by air plasma processing, co-contributed to the surface wettability improvement of PMMA micro-beads.

  5. Prediction of quench and rewet temperatures. [PWR; BWR

    SciTech Connect

    Gunnerson, F. S.

    1980-01-01

    Many postulated nuclear reactor accidents result in high-temperature dryout or film boiling within the nuclear core. In order to mitigate potential fuel rod damage or rod failure, safe or lower fuel rod temperatures must be reestablished by promoting coolant/cladding contact. This process is commonly referred to as quenching or rewetting, and often, these terms are not differentiated. All theoretical predictions of the cooling process by various models based on single or multidimensional analytical and numerical studies require a knowledge of either the quenching or the rewetting temperature. The purpose of this paper is to define quench and rewet temperatures and present a method whereby each may be estimated.

  6. Improving the work function of the niobium surface of SRF cavities by plasma processing

    DOE PAGESBeta

    Tyagi, P. V.; Doleans, M.; Hannah, B.; Afanador, R.; McMahan, C.; Stewart, S.; Mammosser, J.; Howell, M.; Saunders, J.; Degraff, B.; et al

    2016-01-01

    An in situ plasma processing technique using chemically reactive oxygen plasma to remove hydrocarbons from superconducting radio frequency cavity surfaces at room temperature was developed at the spallation neutron source, at Oak Ridge National Laboratory. To understand better the interaction between the plasma and niobium surface, surface studies on small samples were performed. In this article, we report the results from those surface studies. The results show that plasma processing removes hydrocarbons from top surface and improves the surface work function by 0.5₋1.0 eV. Improving the work function of RF surface of cavities can help to improve their operational performance.

  7. Atmospheric pressure plasma processing of polymeric materials utilizing close proximity indirect exposure

    DOEpatents

    Paulauskas, Felix L.; Bonds, Truman

    2016-09-20

    A plasma treatment method that includes providing treatment chamber including an intermediate heating volume and an interior treatment volume. The interior treatment volume contains an electrode assembly for generating a plasma and the intermediate heating volume heats the interior treatment volume. A work piece is traversed through the treatment chamber. A process gas is introduced to the interior treatment volume of the treatment chamber. A plasma is formed with the electrode assembly from the process gas, wherein a reactive species of the plasma is accelerated towards the fiber tow by flow vortices produced in the interior treatment volume by the electrode assembly.

  8. Atmospheric-Pressure Plasma Interaction with Soft Materials as Fundamental Processes in Plasma Medicine.

    PubMed

    Takenaka, Kosuke; Miyazaki, Atsushi; Uchida, Giichiro; Setsuhara, Yuichi

    2015-03-01

    Molecular-structure variation of organic materials irradiated with atmospheric pressure He plasma jet have been investigated. Optical emission spectrum in the atmospheric-pressure He plasma jet has been measured. The spectrum shows considerable emissions of He lines, and the emission of O and N radicals attributed to air. Variation in molecular structure of Polyethylene terephthalate (PET) film surface irradiated with the atmospheric-pressure He plasma jet has been observed via X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR). These results via XPS and FT-IR indicate that the PET surface irradiated with the atmospheric-pressure He plasma jet was oxidized by chemical and/or physical effect due to irradiation of active species.

  9. Atmospheric-Pressure Plasma Interaction with Soft Materials as Fundamental Processes in Plasma Medicine.

    PubMed

    Takenaka, Kosuke; Miyazaki, Atsushi; Uchida, Giichiro; Setsuhara, Yuichi

    2015-03-01

    Molecular-structure variation of organic materials irradiated with atmospheric pressure He plasma jet have been investigated. Optical emission spectrum in the atmospheric-pressure He plasma jet has been measured. The spectrum shows considerable emissions of He lines, and the emission of O and N radicals attributed to air. Variation in molecular structure of Polyethylene terephthalate (PET) film surface irradiated with the atmospheric-pressure He plasma jet has been observed via X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FT-IR). These results via XPS and FT-IR indicate that the PET surface irradiated with the atmospheric-pressure He plasma jet was oxidized by chemical and/or physical effect due to irradiation of active species. PMID:26413628

  10. Characteristics of pulsed internal inductively coupled plasma for next generation display processing.

    PubMed

    Kim, Tae Hyung; Lee, Seung Min; Lee, Chul Hee; Bae, Jeong Oun; Yeom, Geun Young; Kim, Kyong Nam

    2014-12-01

    RF pulsed plasma characteristics of inductively coupled plasma (ICP) sources operated with internal linear type antennas for the next generation display processing were investigated. By applying the rf pulse mode in the ICP source, with decreasing the rf pulse duty percentage, the average electron temperature was decreased and the plasma non-uniformity was improved with decreasing the rf pulse duty percentage. In the case of plasma uniformity, for the same time average rf power of 3 kW to the ICP source, the plasma non-uniformity was improved from 8.4% at 100% of rf duty percentage to 6.4% at 60% of rf duty percentage due to the increased diffusion of the plasma during the pulse-off time. When SiO2 was etched using CF4, the etch rate uniformity was also improved due to the improvement of plasma uniformity. PMID:25971107

  11. Plasma shield for in-air beam processes

    SciTech Connect

    Hershcovitch, Ady

    2008-05-15

    A novel concept/apparatus, the Plasma Shield, is introduced in this paper. The purpose of the Plasma Shield is designed to shield a target object chemically and thermally by engulfing an area subjected to beam treatment with inert plasma. The shield consists of a vortex-stabilized arc that is employed to shield beams and workpiece area of interaction from an atmospheric or liquid environment. A vortex-stabilized arc is established between a beam generating device (laser, ion or electron gun) and a target object. The arc, which is composed of a pure noble gas, engulfs the interaction region and shields it from any surrounding liquids like water or reactive gases. The vortex is composed of a sacrificial gas or liquid that swirls around and stabilizes the arc. The successful Plasma Shield was experimentally established and very high-quality electron beam welding with partial plasma shielding was performed. The principle of the operation and experimental results are discussed in the paper.

  12. Non-photochemical quenching and xanthophyll cycle activities in six green algal species suggest mechanistic differences in the process of excess energy dissipation.

    PubMed

    Quaas, Theresa; Berteotti, Silvia; Ballottari, Matteo; Flieger, Kerstin; Bassi, Roberto; Wilhelm, Christian; Goss, Reimund

    2015-01-01

    In the present study the non-photochemical quenching (NPQ) of four biofilm-forming and two planktonic green algae was investigated by fluorescence measurements, determinations of the light-driven proton gradient and determination of the violaxanthin cycle activity by pigment analysis. It was observed that, despite the common need for efficient photoprotection, the structural basis of NPQ was heterogeneous in the different species. Three species, namely Chlorella saccharophila, Chlorella vulgaris and Bracteacoccus minor, exhibited a zeaxanthin-dependent NPQ, while in the three other species, Tetracystis aeria, Pedinomonas minor and Chlamydomonas reinhardtii violaxanthin de-epoxidation was absent or unrelated to the establishment of NPQ. Acclimation of the algae to high light conditions induced an increase of the NPQ activity, suggesting that a significant part of the overall NPQ was rather inducible than constitutively present in the green algae. Comparing the differences in the NPQ mechanisms with the phylogenetic position of the six algal species led to the conclusion that the NPQ heterogeneity observed in the present study was not related to the phylogeny of the algae but to the environmental selection pressure. Finally, the difference in the NPQ mechanisms in the different species is discussed within the frame of the current NPQ models.

  13. Influence of radiative processes on the ignition of deuterium-tritium plasma containing inactive impurities

    NASA Astrophysics Data System (ADS)

    Gus'kov, S. Yu.; Sherman, V. E.

    2016-08-01

    The degree of influence of radiative processes on the ignition of deuterium-tritium (DT) plasma has been theoretically studied as dependent on the content of inactive impurities in plasma. The analytic criterion of plasma ignition in inertial confinement fusion (ICF) targets is modified taking into account the absorption of intrinsic radiation from plasma in the ignition region. The influence of radiative processes on the DT plasma ignition has been analytically and numerically studied for plasma that contains a significant fraction of inactive impurities either as a result of DT fuel mixing with ICF target ablator material or as a result of using light metal DT-hydrides as solid noncryogenic fuel. It has been shown that the effect of the absorption of intrinsic radiation leads to lower impurity-induced increase in the ignition energy as compared to that calculated in the approximation of optically transparent ignition region.

  14. Theoretical investigations of plasma processes in the ion bombardment thruster

    NASA Technical Reports Server (NTRS)

    Wilhelm, H. E.

    1975-01-01

    A physical model for a thruster discharge was developed, consisting of a spatially diverging plasma sustained electrically between a small ring cathode and a larger ring anode in a cylindrical chamber with an axial magnetic field. The associated boundary-value problem for the coupled partial differential equations with mixed boundary conditions, which describe the electric potential and the plasma velocity fields, was solved in closed form. By means of quantum-mechanical perturbation theory, a formula for the number S(E) of atoms sputtered on the average by an ion of energy E was derived from first principles. The boundary-value problem describing the diffusion of the sputtered atoms through the surrounding rarefied electron-ion plasma to the system surfaces of ion propulsion systems was formulated and treated analytically. It is shown that outer boundary-value problems of this type lead to a complex integral equation, which requires numerical resolution.

  15. Quench ring for a gasifier

    SciTech Connect

    Denbleyker, A.L.

    1989-01-31

    This patent describes a gasifier for the high temperature combustion of a carbonaceous fuel to produce a usable gas, which gasifier includes an insulated shell having a combustion chamber in which the fuel is burned at an elevated temperature and pressure, a quench chamber in the shell holding a liquid bath for cooling products of combustion, a constricted throat communicating the respective combustion chamber and quench chamber, and an elongated dip tube having an inner wall which defines a flow guide path between the combustion chamber and the quench chamber, and having opposed upper and lower edges.

  16. Thin film coating process using an inductively coupled plasma

    DOEpatents

    Kniseley, Richard N.; Schmidt, Frederick A.; Merkle, Brian D.

    1990-01-30

    Thin coatings of normally solid materials are applied to target substrates using an inductively coupled plasma. Particles of the coating material are vaporized by plasma heating, and pass through an orifice to a first vacuum zone in which the particles are accelerated to a velocity greater than Mach 1. The shock wave generated in the first vacuum zone is intercepted by the tip of a skimmer cone that provides a second orifice. The particles pass through the second orifice into a second zone maintained at a higher vacuum and impinge on the target to form the coating. Ultrapure coatings can be formed.

  17. Application of Atmospheric-Pressure Microwave Line Plasma for Low Temperature Process

    NASA Astrophysics Data System (ADS)

    Suzuki, Haruka; Nakano, Suguru; Itoh, Hitoshi; Sekine, Makoto; Hori, Masaru; Toyoda, Hirotaka

    2015-09-01

    Atmospheric pressure (AP) plasmas have been given much attention because of its high cost benefit and a variety of possibilities for industrial applications. In various kinds of plasma production technique, pulsed-microwave discharge plasma using slot antenna is attractive due to its ability of high-density and stable plasma production. In this plasma source, however, size of the plasma has been limited up to a few cm in length due to standing wave inside a waveguide. To solve this, we have proposed a newly-developed AP microwave plasma source that utilizes not standing wave but travelling wave. By using this plasma source, spatially-uniform AP line plasma with 40 cm in length was realized by pure helium discharge in 60 cm slot and with nitrogen gas additive of 1%. Furthermore, gas temperature as low as 400 K was realized in this device. In this study, as an example of low temperature processes, hydrophilic treatment of PET films was performed. Processing speed increased with pulse frequency and a water contact angle of ~20° was easily obtained within 5 s with no thermal damage to the substrate. To evaluate treatment-uniformity of long line length, PET films were treated by 90 cm slot-antenna plasma and uniform treatment performance was confirmed.

  18. Study of Pulsed vs. RF Plasma Properties for Surface Processing Applications

    NASA Astrophysics Data System (ADS)

    Tang, Ricky; Hopkins, Matthew; Barnat, Edward; Miller, Paul

    2015-09-01

    The ability to manipulate the plasma parameters (density, E/N) was previously demonstrated using a double-pulsed column discharge. Experiments extending this to large-surface plasmas of interest to the plasma processing community were conducted. Differences between an audio-frequency pulsed plasma and a radio-frequency (rf) discharge, both prevalent in plasma processing applications, were studied. Optical emission spectroscopy shows higher-intensity emission in the UV/visible range for the pulsed plasma comparing to the rf plasma at comparable powers. Data suggest that the electron energy is higher for the pulsed plasma leading to higher ionization, resulting in increased ion density and ion flux. Diode laser absorption measurements of the concentration of the 1S5 metastable and 1S4 resonance states of argon (correlated with the plasma E/N) provide comparisons between the excitation/ionization states of the two plasmas. Preliminary modeling efforts suggest that the low-frequency polarity switch causes a much more abrupt potential variation to support interesting transport phenomena, generating a ``wave'' of higher temperature electrons leading to more ionization, as well as ``sheath capture'' of a higher density bolus of ions that are then accelerated during polarity switch.

  19. Double Layers in Expanding Plasmas and Their Relevance to the Auroral Plasma Processes

    NASA Technical Reports Server (NTRS)

    Singh, Nagendra; Khazanov, George; Six, N. Frank (Technical Monitor)

    2002-01-01

    When a dense plasma consisting of a cold and a sufficiently warm electron population expands, a rarefaction shock forms. In the expansion of the polar wind in the magnetosphere, it has been previously shown that when a sufficiently warm electron population also exists, in addition to the usual cold ionospheric one, a discontinuity forms in the electrostatic potential distribution along the magnetic field lines. Despite the lack of spatial resolution and the assumption of quasi-neutrality in the polar wind models, such discontinuities have been called double layers (DLs). Recently similar discontinuities have been invoked to partly explain the auroral acceleration of electrons and ions in the upward current region. By means of one-dimensional Vlasov simulations of expanding plasmas, for the first time we make here the connection between (i) the rarefaction shocks, (ii) the discontinuities in the potential distributions, and (iii) DLs. We show that when plasmas expand from opposite directions into a deep density cavity with a potential drop across it and when the plasma on the high-potential side contains two electron populations, the temporal evolution of the potential and the plasma. distribution generates evolving multiple double layers with an extended density cavity between them. One of the DLs is the rarefaction-shock (RFS) and it forms by the reflections of the cold electrons coming from the high-potential side; it supports a part of the potential drop approximately determined by the hot electron temperature.

  20. Comparison endpoint study of process plasma and secondary electron beam exciter optical emission spectroscopy

    SciTech Connect

    Stephan Thamban, P. L.; Yun, Stuart; Padron-Wells, Gabriel; Hosch, Jimmy W.; Goeckner, Matthew J.

    2012-11-15

    Traditionally process plasmas are often studied and monitored by optical emission spectroscopy. Here, the authors compare experimental measurements from a secondary electron beam excitation and direct process plasma excitation to discuss and illustrate its distinctiveness in the study of process plasmas. They present results that show excitations of etch process effluents in a SF{sub 6} discharge and endpoint detection capabilities in dark plasma process conditions. In SF{sub 6} discharges, a band around 300 nm, not visible in process emission, is observed and it can serve as a good indicator of etch product emission during polysilicon etches. Based on prior work reported in literature the authors believe this band is due to SiF{sub 4} gas phase species.

  1. Final report of ''Fundamental Surface Reaction Mechanisms in Fluorocarbon Plasma-Based Processing''

    SciTech Connect

    Gottlieb S. Oehrlein; H. Anderson; J. Cecchi; D. Graves

    2004-09-21

    This report provides a summary of results obtained in research supported by contract ''Fundamental Surface Reaction Mechanisms in Fluorocarbon Plasma-Based Processing'' (Contract No. DE-FG0200ER54608). In this program we advanced significantly the scientific knowledge base on low pressure fluorocarbon plasmas used for patterning of dielectric films and for producing fluorocarbon coatings on substrates. We characterized important neutral and ionic gas phase species that are incident at the substrate, and the processes that occur at relevant surfaces in contact with the plasma. The work was performed through collaboration of research groups at three universities where significantly different, complementary tools for plasma and surface characterization, computer simulation of plasma and surface processes exist. Exchange of diagnostic tools and experimental verification of key results at collaborating institutions, both experimentally and by computer simulations, was an important component of the approach taken in this work.

  2. Holographic quenches with a gap

    NASA Astrophysics Data System (ADS)

    da Silva, Emilia; Lopez, Esperanza; Mas, Javier; Serantes, Alexandre

    2016-06-01

    In order to holographically model quenches with a gapped final hamiltonian, we consider a gravity-scalar theory in anti-de Sitter space with an infrared hard wall. We allow a time dependent profile for the scalar field at the wall. This induces an energy exchange between bulk and wall and generates an oscillating scalar pulse. We argue that such backgrounds are the counterpart of quantum revivals in the dual field theory. We perform a qualitative comparison with the quench dynamics of the massive Schwinger model, which has been recently analyzed using tensor network techniques. Agreement is found provided the width of the oscillating scalar pulse is inversely linked to the energy density communicated by the quench. We propose this to be a general feature of holographic quenches.

  3. Nonlinear plasma processes and the formation of electron kappa distribution

    NASA Astrophysics Data System (ADS)

    Yoon, Peter

    2016-07-01

    The goal of nonequilibrium statistical mechanics is to establish fundamental relationship between the time irreversible macroscopic dynamics and the underlying time reversible behavior of microscopic system. The paradigm of achieving this seemingly paradoxical goal is through the concept of probability. For classical systems Boltzmann accomplished this through his H theorem and his kinetic equation for dilute gas. Boltzmann's H function is the same as classical extensive entropy aside from the minus sign, and his kinetic equation is applicable for short-range molecular interaction. For plasmas, the long-range electromagnetic force dictates the inter-particular interaction, and the underlying entropy is expected to exhibit non-extensive, or non-additive behavior. Among potential models for the non-additive entropy, the celebrated Tsallis entropy is the most well known. One of the most useful fundamental kinetic equations that governs the long-range plasma interaction is that of weak turbulence kinetic theory. At present, however, there is no clear-cut connection between the Tsallis entropy and the kinetic equations that govern plasma behavior. This can be contrasted to Boltzmann's H theorem, which is built upon his kinetic equation. The best one can do is to show that the consequences of Tsallis entropy and plasma kinetic equation are the same, that is, they both imply kappa distribution. This presentation will overview the physics of electron acceleration by beam-generated Langmuir turbulence, and discuss the asymptotic solution that rigorously can be shown to correspond to the kappa distribution. Such a finding is a strong evidence, if not water-tight proof, that there must be profound inter-relatioship between the Tsallis thermostatistical theory and the plasma kinetic theory.

  4. Double Layers in Expanding Plasmas and Their Relevance to the Auroral Plasma Processes

    NASA Technical Reports Server (NTRS)

    Singh, Nagendra; Khazanov, George

    2003-01-01

    When a dense plasma consisting of a cold and a sufficiently warm electron population expands, a rarefaction shock forms [Bezzerides et al., 1978]. In the expansion of the polar wind in the magnetosphere, it has been previously shown that when a sufficiently warm electron population also exists, in addition to the usual cold ionospheric one, a discontinuity forms in the electrostatic potential distribution along the magnetic field lines [Barakat and Schunk, 1984]. Despite the lack of spatial resolution and the assumption of quasi-neutrality in the polar wind models, such discontinuities have been called double layers (DLs). Recently similar discontinuities have been invoked to partly explain the auroral acceleration of electrons and ions in the upward current region [Ergun et al., 2000]. By means of one-dimensional Vlasov simulations of expanding plasmas, for the first time we make here the connection between (1) the rarefaction shocks, (2) the discontinuities in the potential distributions, and (3) DLs. We show that when plasmas expand from opposite directions into a deep density cavity with a potential drop across it and when the plasma on the high-potential side contains hot and cold electron populations, the temporal evolution of the potential and the plasma distribution generates evolving multiple double layers with an ,extended density cavity between them. One of the DLs is the rarefaction-shock (RFS) and it forms by the reflections of the cold electrons coming from the high-potential side; it supports a part of the potential drop approximately determined by the hot electron temperature. The other DLs evolve from charge separations arising either from reflection of ions coming from the low-potential side or stemming from plasma instabilities; they support the rest of the potential drop. The instabilities forming these additional double layers involve electron-ion (e-i) Buneman or ion-ion (i-i) two-stream interactions. The electron-electron two

  5. Observations and Simulations of Formation of Broad Plasma Depletions Through Merging Process

    NASA Technical Reports Server (NTRS)

    Huang, Chao-Song; Retterer, J. M.; Beaujardiere, O. De La; Roddy, P. A.; Hunton, D.E.; Ballenthin, J. O.; Pfaff, Robert F.

    2012-01-01

    Broad plasma depletions in the equatorial ionosphere near dawn are region in which the plasma density is reduced by 1-3 orders of magnitude over thousands of kilometers in longitude. This phenomenon is observed repeatedly by the Communication/Navigation Outage Forecasting System (C/NOFS) satellite during deep solar minimum. The plasma flow inside the depletion region can be strongly upward. The possible causal mechanism for the formation of broad plasma depletions is that the broad depletions result from merging of multiple equatorial plasma bubbles. The purpose of this study is to demonstrate the feasibility of the merging mechanism with new observations and simulations. We present C/NOFS observations for two cases. A series of plasma bubbles is first detected by C/NOFS over a longitudinal range of 3300-3800 km around midnight. Each of the individual bubbles has a typical width of approx 100 km in longitude, and the upward ion drift velocity inside the bubbles is 200-400 m/s. The plasma bubbles rotate with the Earth to the dawn sector and become broad plasma depletions. The observations clearly show the evolution from multiple plasma bubbles to broad depletions. Large upward plasma flow occurs inside the depletion region over 3800 km in longitude and exists for approx 5 h. We also present the numerical simulations of bubble merging with the physics-based low-latitude ionospheric model. It is found that two separate plasma bubbles join together and form a single, wider bubble. The simulations show that the merging process of plasma bubbles can indeed occur in incompressible ionospheric plasma. The simulation results support the merging mechanism for the formation of broad plasma depletions.

  6. Silicon solar cells made by a self-aligned, selective-emitter, plasma-etchback process

    DOEpatents

    Ruby, Douglas S.; Schubert, William K.; Gee, James M.

    1999-01-01

    A potentially low-cost process for forming and passivating a selective emitter. The process uses a plasma etch of the heavily doped emitter to improve its performance. The grids of the solar cell are used to mask the plasma etch so that only the emitter in the region between the grids is etched, while the region beneath the grids remains heavily doped for low contact resistance. This process is potentially low-cost because it requires no alignment. After the emitter etch, a silicon nitride layer is deposited by plasma-enhanced, chemical vapor deposition, and the solar cell is annealed in a forming gas.

  7. Silicon solar cells made by a self-aligned, selective-emitter, plasma-etchback process

    DOEpatents

    Ruby, D.S.; Schubert, W.K.; Gee, J.M.

    1999-02-16

    A potentially low-cost process for forming and passivating a selective emitter. The process uses a plasma etch of the heavily doped emitter to improve its performance. The grids of the solar cell are used to mask the plasma etch so that only the emitter in the region between the grids is etched, while the region beneath the grids remains heavily doped for low contact resistance. This process is potentially low-cost because it requires no alignment. After the emitter etch, a silicon nitride layer is deposited by plasma-enhanced, chemical vapor deposition, and the solar cell is annealed in a forming gas. 5 figs.

  8. Ion-plasma processes of the production of diffusion aluminide coatings

    NASA Astrophysics Data System (ADS)

    Muboyadzhyan, S. A.

    2010-03-01

    A novel ion-plasma process for ecologically safe formation of diffusion aluminide coatings on a substrate made of a superalloy, which has advantages as compared to the well-known thermodiffusion processes of their production, is described. The ion-plasma process is shown to provide the formation of diffusion aluminide coatings on the surface of a superalloy substrate according to various technologies. Owing to alloying with one or several elements from the series Y, Si, Cr, Hf, B, Co, etc., ion-plasma diffusion coatings have higher protective properties than analogous coatings produced by the traditional methods of powder, slip, and gas-circulating aluminizing.

  9. Data processing of absorption spectra from photoionized plasma experiments at Z

    SciTech Connect

    Hall, I. M.; Durmaz, T.; Mancini, R. C.; Bailey, J. E.; Rochau, G. A.

    2010-10-15

    We discuss the processing of x-ray absorption spectra from photoionized plasma experiments at Z. The data was recorded with an imaging spectrometer equipped with two elliptically bent potassium acid phthalate (KAP) crystals. Both time-integrated and time-resolved data were recorded. In both cases, the goal is to obtain the transmission spectra for quantitative analysis of plasma conditions.

  10. Numerical simulation of the coal combustion process initiated by a plasma source

    NASA Astrophysics Data System (ADS)

    Askarova, A. S.; Messerle, V. E.; Ustimenko, A. B.; Bolegenova, S. A.; Maksimov, V. Yu.

    2014-12-01

    Numerical experiments on the torch combustion of the coal dust prepared by a plasma-thermochemical treatment for combustion have been done using the method of three-dimensional simulation. It is shown that the plasma preparation of coal for combustion enables one to optimize the process, improve the conditions for inflammation and combustion and minimize the emissions of harmful substances.

  11. Effects of plasma parameters and collection region on synthesis of iron and nickel aluminide composite particles during thermal plasma processing

    NASA Astrophysics Data System (ADS)

    Suresh, K.; Selvarajan, V.

    2010-02-01

    Iron and Nickel aluminide composite particles were synthesized by non-transferred DC plasma spray torch at atmospheric pressure. Irregular shaped ball milled, micron sized powders were fed in to the plasma flame using argon as carrier gas. The particles got molten and vaporized. The vapour condensed on the walls of the reaction chamber and nanoparticles were formed. The molten particles got spheroidized due to surface tension forces. Powders as formed were collected in the plasma reactor at three different sections (Section A, B and C). These powder particles were characterized by X-ray diffraction (XRD) and scanning electron microscopy (SEM). The particle size and morphology of the composite particles strongly varied depending on the processing parameters and collection region. The results were discussed.

  12. Plasma Astrophysics: Kinetic Processes in Solar and Stellar Coronae, Second Edition

    NASA Astrophysics Data System (ADS)

    Gary, S. Peter

    A collision-less plasma is an ionized fluid that is so hot and tenuous that interactions between individual particles are unimportant. In such a plasma, electric and magnetic fields mediate interactions among particles, and fundamental physics is addressed by kinetic theories that describe not only the spatial and temporal variations of the medium, but also its velocity-space properties. The outer corona of our Sun and the outer coronae of many stars are collision-less plasmas. Thus, the preface begins, ``This textbook is intended as an introduction to the physics of solar and stellar coronae, emphasizing kinetic plasma processes.'' But the content of Plasma Astrophysics extends well beyond the stated purview. In fact, many plasmas of the universe are collisionless, including many space plasmas-those that are subject to in situ measurements by spacecraft-and a wide variety of astrophysical plasmas. Thus, although the parameters and phenomena that characterize the collision-less plasmas of space, the solar corona, and astrophysics are often very different, the physics in each case derives from the same fundamental kinetic plasma theory.

  13. Temperature of hydrogen radio frequency plasma under dechlorination process of polychlorinated biphenyls

    SciTech Connect

    Inada, Y. Abe, K.; Kumada, A.; Hidaka, K.; Amano, K.; Itoh, K.; Oono, T.

    2014-10-27

    It has been reported that RF (radio frequency) hydrogen plasmas promote the dechlorination process of PCBs (polychlorinated biphenyls) under irradiation of MW (microwave). A relative emission intensity spectroscope system was used for single-shot imaging of two-dimensional temperature distributions of RF hydrogen plasmas generated in chemical solutions with several mixing ratios of isopropyl alcohol (IPA) and insulation oil under MW irradiation. Our experimental results showed that the plasma generation frequencies for the oil-contaminating solutions were higher than that for the pure IPA solution. In addition, the plasma temperature in the compound liquids including both oil and IPA was higher than that in the pure IPA and oil solutions. A combination of the plasma temperature measurements and plasma composition analysis indicated that the hydrogen radicals generated in a chemical solution containing the equal volumes of IPA and oil were almost the same amounts of H and H{sup +}, while those produced in the other solutions were mainly H.

  14. Effect of Processing Parameters on Plasma Jet and In-flight Particles Characters in Supersonic Plasma Spraying

    NASA Astrophysics Data System (ADS)

    Wei, Pei; Wei, Zhengying; Zhao, Guangxi; Bai, Y.; Tan, Chao

    2016-09-01

    In supersonic plasma spraying system (SAPS), heat transfer from arc plasma is characterized by several distinct features, such as transport of dissociation and ionization energy and of electrical charges in addition to mass transport. The thermodynamic and transport properties of plasma jet were influenced by several main parameters such as primary gas flow rate, the H2 vol.% and current intensity A. This paper first analyzes the effect of these parameters on the temperature and velocity of plasma jet theoretically. Further, the loading particles were melted and accelerated by plasma jet. Effects of several main parameters such as carrier gas flow rate, the H2 vol.%, the current intensity, the voltage and the spraying distance on temperature and velocity of in-flight particle were studied experimentally. The average maximum temperature and velocity of in-flight particle at any given parameters were systematically quantified. Optimal SAPS process parameters were given in this paper. In general, increasing the particles impacting velocity and surface temperature can improve the maximum spreading factor and decrease the coating porosity.

  15. Educational software for the visualization of space plasma processes

    NASA Technical Reports Server (NTRS)

    Russell, C. T.; Le, G.; Luhmann, J. G.; Littlefield, B.

    1995-01-01

    The UCLA Space Physics Group has developed educational software composed of a series of modules to assist students with understanding basic concepts of space plasmas and charged particle motion. Present modules cover planetary magnetospheres, charged particle motion, cold plasma waves, collisionless shock waves, and solar wind. The software is designed around the principle that students can learn more by doing rather than by reading or listening. The programs provide a laboratory-like environment in which the student can control, observe, and measure complex behavior. The interactive graphics environment allows the student to visualize the results of his or her experimentation and to try different parameters as desired. The current version of the software runs on UNIX-based operating systems in an X-Windows environment. It has been used in a classroom setting at both UCLA and the University of California at San Diego.

  16. Simulated plasma immersion ion implantation processing of thin wires

    SciTech Connect

    Lejars, A.; Duday, D.; Wirtz, T.; Manova, D.; Maendl, S.

    2010-09-15

    In plasma immersion ion implantation, the dependencies of sheath expansion and ion flux density on substrate geometry are well established. However, effects of extreme diameter variations have not been investigated explicitly. Using an analytical simulation code assuming an infinite mean free path, the sheath expansion, ion flux density, and resulting substrate temperature are explored down to wire diameters of 150 {mu}m. Comparing the results for planar substrates and cylindrical, thin wires, a reduction in the sheath width up to a factor of 10, a faster establishing of a new equilibrium sheath position, and an increase in the ion fluence by a factor of 100 is encountered. The smaller plasma sheath allows for a denser packing of wires during the treatment than for planar substrates. Additionally, the implantation time is reduced, allowing a fast wire transport through the chamber, further increasing the throughput.

  17. Thermal Plasmas: Influence of Current Modulation on Process Performance

    NASA Astrophysics Data System (ADS)

    Schein, Jochen

    2015-09-01

    Due to the widespread industrial use of thermal plasmas in the field of joining, cutting and the application of coatings new challenges arise owed to the advent of new materials or the drive to reduce cost or improve quality. These challenges may be met by using technological innovations like innovative fast power supplies. In the presence of strong gas flows and a fixed cathodic attachment the anode attachment position is determined by an unstable balance between the drag force on the plasma column exerted by the gas and the Lorentz Force due to the system's magnetic field distribution, leading to a constant arc motion and arc voltage fluctuation. Thus by supplying a sufficiently high and steep current pulse a re-positioning might be initiated by a sudden change of the Lorentz Force thus an externally controlled movement of the arc would be possible. In wire arc spraying a pulsed current is imposed upon the DC supply of the wire arc system. It is observed that steep current increases tend to produce sudden current drops, indicating a jump of the arc. For a certain pulse frequency this pulsing leads to a controlled motion of the arc along the electrode surfaces. Coatings produced with this technology exhibited a lower porosity than DC sprayed coatings and a lower oxide content. In collaboration with Alexander Atzberger and Michal Szulc, Universitaet der Bundeswehr Muenchen; Institute for plasma technology and mathematics (LPT) Neubiberg, Germany. This work was supported by AiF (Arbeitsgemeinschaft industrielle Forschung).

  18. Electron beam control rf discharges for plasma processing

    SciTech Connect

    Kushner, M.J.; Ruzic, D.N.; Yang, J.

    1995-12-31

    Reactive Ion Etching (RIE) discharges for microelectronics fabrication suffer from the inability to separately control plasma density and ion power flux to the wafer. Inductively coupled plasma (ICP) and electron cyclotron resonance (ECR) reactors have been developed to provide some degree of independent control. This is accomplished by arranging for ionization to be provided dominantly by the applied electromagnetic instead of the rf bias to the substrate. Both ICP and ECR reactors, though, optimally operate at low gas pressures, and are not typically used for intermediate to high pressure etching and deposition systems. To address the higher pressure range, a hybrid electron beam/RIE discharge system (EB-RIE) has been developed. In the EB-RIE system, a planar electron beam (1--3 kV) is injected into the plasma chamber above and parallel to the wafer. An rf bias is separately applied to the substrate. A 2-dimensional model of the EB-RIE reactor has been developed to investigate the scaling of the device and analyze previous experimental measurements. Results from the model are discussed for Ar and Ar/SiH{sub 4} gas mixtures in which the beam energy, gas pressure and positioning of the beam are varied.

  19. Jet quenching from QCD evolution

    NASA Astrophysics Data System (ADS)

    Chien, Yang-Ting; Emerman, Alexander; Kang, Zhong-Bo; Ovanesyan, Grigory; Vitev, Ivan

    2016-04-01

    Recent advances in soft-collinear effective theory with Glauber gluons have led to the development of a new method that gives a unified description of inclusive hadron production in reactions with nucleons and heavy nuclei. We show how this approach, based on the generalization of the DGLAP evolution equations to include final-state medium-induced parton shower corrections for large Q2 processes, can be combined with initial-state effects for applications to jet quenching phenomenology. We demonstrate that the traditional parton energy loss calculations can be regarded as a special soft-gluon emission limit of the general QCD evolution framework. We present phenomenological comparison of the SCETG -based results on the suppression of inclusive charged hadron and neutral pion production in √{sNN }=2.76 TeV lead-lead collisions at the Large Hadron Collider to experimental data. We also show theoretical predictions for the upcoming √{sNN }≃5.1 TeV Pb +Pb run at the LHC.

  20. Organization by Gordon Research Conferences of the 2012 Plasma Processing Science Conference 22-27 July 2012

    SciTech Connect

    Chang, Jane

    2012-07-27

    The 2012 Gordon Research Conference on Plasma Processing Science will feature a comprehensive program that will highlight the most cutting edge scientific advances in plasma science and technology as well as explore the applications of this nonequilibrium medium in possible approaches relative to many grand societal challenges. Fundamental science sessions will focus on plasma kinetics and chemistry, plasma surface interactions, and recent trends in plasma generation and multi-phase plasmas. Application sessions will explore the impact of plasma technology in renewable energy, the production of fuels from renewable feedstocks and carbon dioxide neutral solar fuels (from carbon dioxide and water), and plasma-enabled medicine and sterilization.

  1. Molecular insights into Zeaxanthin-dependent quenching in higher plants

    PubMed Central

    Xu, Pengqi; Tian, Lijin; Kloz, Miroslav; Croce, Roberta

    2015-01-01

    Photosynthetic organisms protect themselves from high-light stress by dissipating excess absorbed energy as heat in a process called non-photochemical quenching (NPQ). Zeaxanthin is essential for the full development of NPQ, but its role remains debated. The main discussion revolves around two points: where does zeaxanthin bind and does it quench? To answer these questions we have followed the zeaxanthin-dependent quenching from leaves to individual complexes, including supercomplexes. We show that small amounts of zeaxanthin are associated with the complexes, but in contrast to what is generally believed, zeaxanthin binding per se does not cause conformational changes in the complexes and does not induce quenching, not even at low pH. We show that in NPQ conditions zeaxanthin does not exchange for violaxanthin in the internal binding sites of the antennas but is located at the periphery of the complexes. These results together with the observation that the zeaxanthin-dependent quenching is active in isolated membranes, but not in functional supercomplexes, suggests that zeaxanthin is acting in between the complexes, helping to create/participating in a variety of quenching sites. This can explain why none of the antennas appears to be essential for NPQ and the multiple quenching mechanisms that have been observed in plants. PMID:26323786

  2. Method for atmospheric pressure reactive atom plasma processing for surface modification

    DOEpatents

    Carr, Jeffrey W.

    2009-09-22

    Reactive atom plasma processing can be used to shape, polish, planarize and clean the surfaces of difficult materials with minimal subsurface damage. The apparatus and methods use a plasma torch, such as a conventional ICP torch. The workpiece and plasma torch are moved with respect to each other, whether by translating and/or rotating the workpiece, the plasma, or both. The plasma discharge from the torch can be used to shape, planarize, polish, and/or clean the surface of the workpiece, as well as to thin the workpiece. The processing may cause minimal or no damage to the workpiece underneath the surface, and may involve removing material from the surface of the workpiece.

  3. Solution processed organic light-emitting diodes using the plasma cross-linking technology

    NASA Astrophysics Data System (ADS)

    He, Kongduo; Liu, Yang; Gong, Junyi; Zeng, Pan; Kong, Xun; Yang, Xilu; Yang, Cheng; Yu, Yan; Liang, Rongqing; Ou, Qiongrong

    2016-09-01

    Solution processed multilayer organic light-emitting diodes (OLEDs) present challenges, especially regarding dissolution of the first layer during deposition of a second layer. In this work, we first demonstrated a plasma cross-linking technology to produce a solution processed OLED. The surfaces of organic films can be cross-linked after mixed acetylene and Ar plasma treatment for several tens of seconds and resist corrosion of organic solvent. The film thickness and surface morphology of emissive layers (EMLs) with plasma treatment and subsequently spin-rinsed with chlorobenzene are nearly unchanged. The solution processed triple-layer OLED is successfully fabricated and the current efficiency increases 50% than that of the double-layer OLED. Fluorescent characteristics of EMLs are also observed to investigate factors influencing the efficiency of the triple-layer OLED. Plasma cross-linking technology may open up a new pathway towards fabrication of all-solution processed multilayer OLEDs and other soft electronic devices.

  4. The structural basis of non-photochemical quenching is revealed?

    PubMed

    Cogdell, Richard J

    2006-02-01

    Light-harvesting complex II (LHCII, the major plant light-harvesting pigment-protein complex, efficiently harvests light-energy. However, if the incident light intensity is too high and photosynthesis becomes saturated, LHCII can switch into a quenching state that prevents photodamage. This important process is called non-photochemical quenching, or NPQ, and represents feedback control. Andrew Pascal et al. have recently proposed a detailed model of NPQ based upon the crystal structure of LHCII from spinach.

  5. The effects of plasma-processing conditions on the morphology of adherent human blood platelets

    SciTech Connect

    Murugesan, R.; Hanley, E.; Lauer, J. L.; Shohet, J. L.; Albrecht, R. M.; Heintz, J. A.; Oliver, J. A.

    2008-05-01

    Hematocompatibility and nonfouling properties of materials are crucial for the development of small-scale biomedical devices. This study examines the adhesion and morphology of purified human platelets on plasma-polymerized tetraglyme-coated glass substrates. The effect of varying the plasma-processing parameters on platelet responses was determined using scanning electron microscopy. Images of platelets on the coated surfaces show that a significant reduction in platelet adhesion and spreading can be achieved as the processing parameters are varied.

  6. Control of plasma process by use of harmonic frequency components of voltage and current

    DOEpatents

    Miller, Paul A.; Kamon, Mattan

    1994-01-01

    The present invention provides for a technique for taking advantage of the intrinsic electrical non-linearity of processing plasmas to add additional control variables that affect process performance. The technique provides for the adjustment of the electrical coupling circuitry, as well as the electrical excitation level, in response to measurements of the reactor voltage and current and to use that capability to modify the plasma characteristics to obtain the desired performance.

  7. Enhancement mechanism of H- production and suitable configurations for materials processing in a magnetized sheet plasma

    NASA Astrophysics Data System (ADS)

    Ramos, Henry J.; Villamayor, Michelle Marie S.; Mella, Aubrey Faith M.; Salamania, Janella Mae R.; Villanueva, Matthew Bryan P.; Viloan, Rommel Paulo B.

    2014-08-01

    A magnetized sheet plasma ion source was developed for steady state high density plasma with strong density and high temperature gradients. This feature provides efficient formation of negative hydrogen (H-) ions over a wide beam extraction area through the electron volume process. A hexapole confinement at the cathode, addition of argon and magnesium seeding led to the increase of H- yield. The device configuration is suitable for plasma based materials processing namely, synthesis of TiN, SiH, SnO2, and the formation of advanced MAX phase materials Ti2AlC, Ti2CdC and NbAlC.

  8. The contribution of dissociative processes to the production of atomic lines in hydrogen plasmas

    NASA Technical Reports Server (NTRS)

    Kunc, J. A.

    1985-01-01

    The contribution of molecular dissociative processes to the production of atomic lines is considered for a steady-state hydrogen plasma. If the contribution of dissociative processes is dominant, a substantial simplification in plasma diagnostics can be achieved. Numerical calculations have been performed for the production of Balmer alpha, beta, and gamma lines in hydrogen plasmas with medium and large degrees of ionization (x greater than about 0.0001) and for electron temperatures of 5000-45,000 K and electron densities of 10 to the 10th to 10 to the 16th/cu cm.

  9. Data Processing from Micro-Plasma Gas Analytical Sensor

    NASA Astrophysics Data System (ADS)

    Mustafaev, Alexander; Tsyganov, Alexander

    2011-10-01

    Theoretical consideration of signal formation at micro-plasma gas analyzer based on Collisional Electron Spectroscopy (CES) and experimental results on CES sensor are presented. It is demonstrated that a diffusion path confinement for characteristic electrons provides a possibility to measure electrons energy distribution function (EEDF) and to find characteristic spectra of species at high (up to atmospheric) gas pressure. Simple micro-plasma CES sensor of two plane parallel electrode configuration with current-voltage measurement in afterglow discharge may be operated in two possible modes. The first mode presumes application of classic 2-nd derivative of current-voltage curve to select characteristic peaks in electron energy spectra of the species to be detected. In the case of a deeper collisional dissipation of characteristic peaks, a 3-rd derivative may be used. Said derivatives were obtained by differentiating of a spline providing least-squares approximation of current-voltage curve. Model and experimental electron energy spectra of pair He metastables collisions in dependence of inter-electrode gap are discussed. Theoretical consideration of signal formation at micro-plasma gas analyzer based on Collisional Electron Spectroscopy (CES) and experimental results on CES sensor are presented. It is demonstrated that a diffusion path confinement for characteristic electrons provides a possibility to measure electrons energy distribution function (EEDF) and to find characteristic spectra of species at high (up to atmospheric) gas pressure. Simple micro-plasma CES sensor of two plane parallel electrode configuration with current-voltage measurement in afterglow discharge may be operated in two possible modes. The first mode presumes application of classic 2-nd derivative of current-voltage curve to select characteristic peaks in electron energy spectra of the species to be detected. In the case of a deeper collisional dissipation of characteristic peaks, a 3-rd

  10. Rapid Sterilization of Escherichia coli by Solution Plasma Process

    NASA Astrophysics Data System (ADS)

    Andreeva, Nina; Ishizaki, Takahiro; Baroch, Pavel; Saito, Nagahiro

    2012-12-01

    Solution plasma (SP), which is a discharge in the liquid phase, has the potential for rapid sterilization of water without chemical agents. The discharge showed a strong sterilization performance against Escherichia coli bacteria. The decimal value (D value) of the reduction time for E. coli by this system with an electrode distance of 1.0 mm was estimated to be approximately 1.0 min. Our discharge system in the liquid phase caused no physical damage to the E. coli and only a small increase in the temperature of the aqueous solution. The UV light generated by the discharge was an important factor in the sterilization of E. coli.

  11. Processes with neutral hydrogen and deuterium molecules relevant to edge plasma in tokamaks

    NASA Astrophysics Data System (ADS)

    Cadez, I.; Markelj, S.; Rupnik, Z.; Pelicon, P.

    2008-07-01

    Detailed understanding and characterization of plasma-wall interaction and edge plasma in present tokamaks and future fusion reactors is becoming more and more important due to the ITER project. Involved processes determine the physical and chemical sputtering of the wall material, fuel retention in exposed material, edge plasma properties, disruption phenomena etc. Neutral hydrogen atoms and molecules are present in the edge plasma. They are continuously generated by ion recombination on the wall of the fusion reactor and on the other plasma facing components and subsequently reemitted in the plasma. Neutral molecules are especially important for plasma detachment in tokamak divertors. The interaction of excited neutral molecules with the walls and their importance for the edge plasma is still not well understood since there are not many experimental studies of relevant processes. Moreover, spectroscopic results from tokamak edge plasma are dominated by processes involving ions and electrons, so that direct evidence of the influence of neutrals is difficult to extract. Direct correlation of the observed phenomena to the processes with neutrals is mainly possible by numerical simulations. We have constructed a set-up for vibrational spectroscopy of hydrogen molecules (H_2 and D_2) that is based on the properties of the dissociative electron attachment in hydrogen in order to facilitate dedicated experimental studies of relevant processes with hydrogen molecules. For the same purpose we also developed a technique for in-situ hydrogen depth profiling on the samples exposed to the controlled hydrogen atmosphere. This is done by Ion Beam Analytical (IBA) method ERAD (Elastic Recoil Detection Analysis), utilizing 4.2 MeV probing beam of ^7Li^2+ ions. A short description of experimental techniques and results on chemical erosion of graphite layers, production of vibrationally excited hydrogen molecules on tungsten and isotope exchange on tungsten are to be presented in

  12. Transport processes in magnetically confined plasmas in the nonlinear regime

    SciTech Connect

    Sonnino, Giorgio

    2006-06-15

    A field theory approach to transport phenomena in magnetically confined plasmas is presented. The thermodynamic field theory (TFT), previously developed for treating the generic thermodynamic system out of equilibrium, is applied to plasmas physics. Transport phenomena are treated here as the effect of the field linking the thermodynamic forces with their conjugate flows combined with statistical mechanics. In particular, the Classical and the Pfirsch-Schlueter regimes are analyzed by solving the thermodynamic field equations of the TFT in the weak-field approximation. We found that, the TFT does not correct the expressions of the ionic heat fluxes evaluated by the neoclassical theory in these two regimes. On the other hand, the fluxes of matter and electronic energy (heat flow) is further enhanced in the nonlinear Classical and Pfirsch-Schlueter regimes. These results seem to be in line with the experimental observations. The complete set of the electronic and ionic transport equations in the nonlinear Banana regime, is also reported. A paper showing the comparison between our theoretic results and the experimental observations in the JET machine is currently in preparation.

  13. Three-Dimensional Integrated Micro Solution Plasmas for Nano Materials Processing

    NASA Astrophysics Data System (ADS)

    Shirafuji, Tatsuru

    2012-10-01

    In contrast to the conventional solution chemistry, the solution plasma processing (SPP), which has been invented by Osamu Takai and Nagahiro Saito (Nagoya University), involves accelerated electrons which contribute to generate active chemical species, such as radicals, ions, UV photons and metastable excited atoms. Such active species are expected to enhance through-put of the solution chemistry and to promote the reactions which do not proceed without catalysts. In our previous work, we have successfully obtained glow discharges in water, and applied this technique to modify the surface of nano-materials. Since the previous solution plasma is ignited in a small volume between two stylus electrodes, actual treatment area or volume should be enlarged for practical industrial application. In the case of gas phase processes, large area processing is realized by producing large area plasmas. In the case of SPP, however, large volume plasma in liquid is meaningless, because the most important region is gas-liquid interface. Thus, preparation of large number of tiny plasmas (microplasmas) is rather important in the case of SPP. This can be named as ``integrated micro solution plasma.'' In order to realize the integrated micro-solution plasmas, we have recently utilized interfaces between a plane dielectric plate and porous dielectric material, and successfully obtained large area integrated micro solution plasmas in two dimensions. In this work, we report that three-dimensionally integrated plasmas can be obtained in a porous dielectric material, and demonstrate that Au nano-particles can be synthesized by using this technique. This work has been partly supported by the CREST/JST, the Knowledge Cluster Initiative Tokai Region Nanotechnology Manufacturing Cluster, Grant-in-Aid for Scientific Research on Innovative Areas ``Frontier science of interactions between plasmas and nano-interfaces'' by the MEXT, and Grant-in-Aid for Scientific Research (C) by the JSPS.

  14. Neoclassical plasma viscosity and transport processes in non-axisymmetric tori

    NASA Astrophysics Data System (ADS)

    Shaing, K. C.; Ida, K.; Sabbagh, S. A.

    2015-11-01

    Neoclassical transport processes are important to the understanding of plasma confinement physics in doubly periodic magnetized toroidal plasmas, especially, after the impact of the momentum confinement on the particle and energy confinement is recognized. Real doubly periodic tori in general are non-axisymmetric, with symmetric tori as a special case. An eight-moment approach to transport theory with plasma density N, plasma pressure p, mass flow velocity V and heat flow q as independent variables is adopted. Transport processes are dictated by the solutions of the momentum and heat flux balance equations. For toroidal plasma confinement devices, the first order (in the gyro-radius ordering) plasma flows are on the magnetic surface to guarantee good plasma confinement and are thus two-dimensional. Two linearly independent components of the momentum equation are required to determine the flows completely. Once this two-dimensional flow is relaxed, i.e. the momentum equation reaches a steady state, plasmas become ambipolar, and all the transport fluxes are determined through the flux-force relation. The flux-force relation is derived both from the kinetic definitions for the transport fluxes and from the manipulation of the momentum and heat flux balance equations to illustrate the nature of the transport fluxes by examining their corresponding driven forces and their roles in the momentum and heat flux balance equations. Steady-state plasma flows are determined by the components of the stress and heat stress tensors in the momentum and heat flux balance equations. This approach emphasizes the pivotal role of the momentum equation in the transport processes and is particularly useful in modelling plasma flows in experiments. The methodology for neoclassical transport theory is applied to fluctuation-driven transport fluxes in the quasilinear theory to unify these two theories. Experimental observations in tokamaks and stellarators for the physics discussed are

  15. In Situ Monitoring of Plasma Spraying Process by Laser Acoustic Emission Method

    NASA Astrophysics Data System (ADS)

    Ito, Kaita; Enoki, Manabu; Watanabe, Makoto; Kuroda, Seiji

    Estimation of microfractures in ceramic coating layer during plasma spraying process is critical for its reliability. Acoustic emission (AE) method enables in-process monitoring of such microfractures. Laser AE method was adopted to realize the monitoring of plasma spraying process by non-contact detection of AE with laser interferometer. Also a high performance method for noise reduction of laser AE waveform was investigated. In this new method, laser AE signal was continuously sampled and transformed into spectrogram by time-frequency analysis to cut out noise component effectively. After this noise reduction process, inverse transform was applied to obtain a clear AE signals in time domain. Whole these processes can be done in real time. The effectiveness of this method was confirmed by a detection test of simulated AE and successfully applied to the monitoring of plasma spraying process. Two types of AE events with different duration time range were found and the sources of these AE were presumed.

  16. The variable polarity plasma arc welding process: Its application to the Space Shuttle external tank

    NASA Technical Reports Server (NTRS)

    Nunes, A. C., Jr.; Bayless, O. E., Jr.; Jones, C. S., III; Munafo, A. P.; Wilson, W. A.

    1983-01-01

    The technical history of the variable polarity plasma arc (VPPA) welding process being introduced as a partial replacement for the gas shielded tungsten arc process in assembly welding of the space shuttle external tank is described. Interim results of the weld strength qualification studies, and plans for further work on the implementation of the VPPA process are included.

  17. Dry and clean age hardening of aluminum alloys by high-pressure gas quenching

    NASA Astrophysics Data System (ADS)

    Irretier, A.; Kessler, O.; Hoffmann, F.; Mayr, P.

    2004-10-01

    When precipitation-hardenable aluminum parts are water quenched, distortion occurs due to thermal stresses. Thereby, a costly reworking is necessary, and for this reason polymer quenchants are often used to reduce distortion, with the disadvantage that the quenched parts have to be cleaned after quenching. In opposition to liquid quenchants, gas quenching may decrease distortion due to the better temperature uniformity during quenching. Furthermore, cleaning of the quenched parts can be avoided because it is a dry process. For this purpose, a heat-treating process was evaluated that included a high-pressure gasquenching step. Gas quenching was applied to different aluminum alloys (i.e., 2024, 6013, 7075, and A357.0), and tensile tests have been carried out to determine the mechanical properties after solution annealing, gas quenching, and aging. Besides high-pressure gas quenching, alloy 2024 was quenched at ambient pressure in a gas nozzle field. The high velocity at the gas outlet leads to an accelerated cooling of the aluminum alloy in this case. Aluminum castings and forgings can be classified as an interesting field of application of these quenching methods due to their near-net shape before the heat treatment. Cost savings would be possible due to the reduced distortion, and therefore, less reworking after the precipitation hardening.

  18. An alternative method for correcting fluorescence quenching

    NASA Astrophysics Data System (ADS)

    Biermann, L.; Guinet, C.; Bester, M.; Brierley, A.; Boehme, L.

    2015-01-01

    Under high light intensity, phytoplankton protect their photosystems from bleaching through non-photochemical quenching processes. The consequence of this is suppression of fluorescence emission, which must be corrected when measuring in situ yield with fluorometers. We present data from the Southern Ocean, collected over five austral summers by 19 southern elephant seals tagged with fluorometers. Conventionally, fluorescence data collected during the day (quenched) were corrected using the limit of the mixed layer, assuming that phytoplankton are uniformly mixed from the surface to this depth. However, distinct deep fluorescence maxima were measured in approximately 30% of the night (unquenched) data. To account for the evidence that chlorophyll is not uniformly mixed in the upper layer, we propose correcting from the limit of the euphotic zone, defined as the depth at which photosynthetically available radiation is ~ 1% of the surface value. Mixed layer depth exceeded euphotic depth over 80% of the time. Under these conditions, quenching was corrected from the depth of the remotely derived euphotic zone Zeu, and compared with fluorescence corrected from the depth of the density-derived mixed layer. Deep fluorescence maxima were evident in only 10% of the day data when correcting from mixed layer depth. This was doubled to 21% when correcting from Zeu, more closely matching the unquenched (night) data. Furthermore, correcting from Zeu served to conserve non-uniform chlorophyll features found between the 1% light level and mixed layer depth.

  19. Spontaneous quenches of a high temperature superconducting pancake coil

    SciTech Connect

    Lue, J.W.; Lubell, M.S.; Aized, D.; Campbell, J.M.; Schwall, R.E.

    1995-09-01

    A double-pancake coil made of Bi-2223/Ag high temperature superconducting (HTS) tape was constructed with an embedded heater and graded conductors to study the stability and quench propagation in HTS coils. The experiments were performed with liquid nitrogen and gaseous helium cooling in temperatures ranging from 5 to 77 K. The coil was very stable, and no ``normal`` zone was sustained or propagated with local pulsed heating. However, spontaneous quenches of the cod were experienced. This was found to be the result of having the coil current higher than that of the lower I{sub c} sections of the coil for a long time. This quench process took minutes to develop--much longer than would be expected in a low temperature superconducting coil. The quench behaved more like a spreading and continuous heating of an increasingly larger partially resistive section of the coil than like a sequential ``normal`` front propagation.

  20. Simulating Zeno physics by a quantum quench with superconducting circuits

    NASA Astrophysics Data System (ADS)

    Tong, Qing-Jun; An, Jun-Hong; Kwek, L. C.; Luo, Hong-Gang; Oh, C. H.

    2014-06-01

    Studying out-of-equilibrium physics in quantum systems under quantum quench is of vast experimental and theoretical interest. Using periodic quantum quenches, we present an experimentally accessible scheme to simulate the quantum Zeno and anti-Zeno effects in an open quantum system of a single superconducting qubit interacting with an array of transmission line resonators. The scheme is based on the following two observations: First, compared with conventional systems, the short-time nonexponential decay in our superconducting circuit system is readily observed; and second, a quench-off process mimics an ideal projective measurement when its time duration is sufficiently long. Our results show the active role of quantum quench in quantum simulation and control.

  1. Quench dynamics in SRF cavities: can we locate the quench origin with 2nd sound?

    SciTech Connect

    Maximenko, Yulia; Segatskov, Dmitri A.; /Fermilab

    2011-03-01

    A newly developed method of locating quenches in SRF cavities by detecting second-sound waves has been gaining popularity in SRF laboratories. The technique is based on measurements of time delays between the quench as determined by the RF system and arrival of the second-sound wave to the multiple detectors placed around the cavity in superfluid helium. Unlike multi-channel temperature mapping, this approach requires only a few sensors and simple readout electronics; it can be used with SRF cavities of almost arbitrary shape. One of its drawbacks is that being an indirect method it requires one to solve an inverse problem to find the location of a quench. We tried to solve this inverse problem by using a parametric forward model. By analyzing the data we found that the approximation where the second-sound emitter is a near-singular source does not describe the physical system well enough. A time-dependent analysis of the quench process can help us to put forward a more adequate model. We present here our current algorithm to solve the inverse problem and discuss the experimental results.

  2. Time-Space Position of Warm Dense Matter in Laser Plasma Interaction Process

    SciTech Connect

    Cao, L F; Uschmann, I; Forster, E; Zamponi, F; Kampfer, T; Fuhrmann, A; Holl, A; Redmer, R; Toleikis, S; Tschentscher, T; Landen, O L; Glenzer, S H

    2006-09-25

    Laser plasma interaction experiments have been perform performed using an fs Titanium Sapphire laser. Plasmas have been generated from planar PMMA targets using single laser pulses with 3.3 mJ pulse energy, 50 fs pulse duration at 800 nm wavelength. Electron density distributions of the plasmas in different delay times have been characterized by means of Nomarski Interferometry. Experimental data were cautiously compared with relevant 1D numerical simulation. Finally these results provide a first experience of searching for the time-space position of the so-called warm dense plasma in an ultra fast laser target interaction process. These experiments aim to prepare near solid-density plasmas for Thomson scattering experiments using the short wavelength free-electron laser FLASH, DESY Hamburg.

  3. High frequency atmospheric cold plasma treatment system for materials surface processing

    NASA Astrophysics Data System (ADS)

    Tudoran, Cristian D.; Surducan, Vasile; Anghel, Sorin D.

    2012-02-01

    The paper presents a new laboratory-made plasma treatment system. The power source which generates the plasma is based on a modern half-bridge type inverter circuit working at a frequency of 4 MHz, and giving an output power of about 200 W. The inverter is fed directly from the mains voltage and features high speed protection circuits for both over voltage and over current protection, making the system light and easy to operate. The output of the inverter is connected to the resonant circuit formed by a Tesla coil and the dielectric barrier discharge plasma chamber. The plasma is generated at atmospheric pressure in argon, helium or mixtures of helium and small quantities of argon. It is a cold discharge (Tgas < 150°C) with a homogeneous structure. The plasma generates chemically active species, especially O and OH, which could be important in various applications such as the treatment and processing of materials surfaces.

  4. Cold plasma processing of local planetary ores for oxygen and metallurgically important metals

    NASA Technical Reports Server (NTRS)

    Lynch, D. C.; Bullard, D.; Ortega, R.

    1991-01-01

    The utilization of a cold or nonequilibrium plasma in chlorination processing is discussed. Titanium dioxide (TiO2) was successfully chlorinated at temperatures between 700 and 900 C without the aid of carbon. In addition to these initial experiments, a technique was developed for determining the temperature of a specimen in a plasma. Development of that technique has required evaluating the emissivity of TiO2, ZrO2, and FeOTiO2 and analyzing the specimen temperature in a plasma as a function of both power absorbed by the plasma and the pressure of the plasma. The mass spectrometer was also calibrated with TiCl4 and CCl4 vapor.

  5. Continuum limit of quenched theories

    SciTech Connect

    Holdom, B.

    1989-02-27

    We study chiral-symmetry breaking in quenched gauge theories with ultraviolet cutoff ..lambda.., to all orders in the gauge coupling. For large ..lambda../kappa, where kappa is the chiral-symmetry-breaking scale, we derive ..lambda../kappaproportionalexp(const/ ..sqrt..(..cap alpha..-..cap alpha../sub c/) as ..cap alpha --> cap alpha../sub c/+. This is a gauge-invariant, universal consequence of quenched theories. But we argue that this relation does not define a ..beta.. function. We also obtain an explicit expression for the self-energy ..sigma..(p) which applies over most of the range kappa

  6. PREFACE: 13th High-Tech Plasma Processes Conference (HTPP-2014)

    NASA Astrophysics Data System (ADS)

    2014-11-01

    The High-Tech Plasma Processes - 13th European Plasma Conference (HTPP-2014) was held in Toulouse (France) on 22-27 June 2014. The conference series started in 1990 as a thermal plasma conference and has gradually expanded to include other related topics. Now the High-Tech Plasma Processes - European Plasma Conference (HTPP) is an international conference organised in Europe every two years with topics encompassing the whole field of plasma processing science. The aim of the conference is to bring different scientific communities together, to facilitate contacts between science, technology and industry and to provide a platform for the exploration of both the fundamental topics and new applications of plasmas. For this edition of HTPP, as was the case for the last, we have acheived a well balanced participation from the communities of both thermal and non-thermal plasma researchers. 142 people from 17 countries attended the conference with the total number of contributions being 155, consisting of 8 plenary and 8 invited talks plus 51 oral and 88 poster contributions. We have received numerous papers corresponding to the contributions of HTPP-2014 that have been submitted for publication in this volume of Journal of Physics: Conference Series. Each submitted contribution has been peer reviewed (60 referees with at least two reviewing each paper) and the Editors are very grateful to the referees for their careful support in improving the original manuscripts. In total, 52 manuscripts have been accepted for publication covering a range of topics of plasma processing science from plasma fundamentals to process applications through to experiments, diagnostics and modelling. We have grouped the papers into the following 5 topics: - Arc-Materials Interaction and Metallurgy - Plasma Torches and Spraying - Synthesis of Powders and Nanomaterials - Deposition and Surface Treatment - Non-Equilibrium Plasmas We deeply thank the authors for their enthusiastic and high

  7. Surface engineering of glazing materials and structures using plasma processes

    SciTech Connect

    Anders, Andre; Monteiro, Othon R.

    2003-04-10

    A variety of coatings is commercially produced on a very large scale, including transparent conducting oxides and multi-layer silver-based low-emissivity and solar control coatings. A very brief review of materials and manufacturing process is presented and illustrated by ultrathin silver films and chevron copper films. Understanding the close relation between manufacturing processes and bulk and surface properties of materials is crucial for film growth and self-assembly processes.

  8. Characterization of an oxygen plasma process for cleaning packaged semiconductor devices. Final report

    SciTech Connect

    Adams, B.E.

    1996-11-01

    The purpose of this research was to experimentally determine the operating {open_quotes}window{close_quotes} for an oxygen plasma cleaning process to be used on microelectronics components just prior to wire bonding. The process was being developed to replace one that used vapor degreasing with trichlorotrifluoroethane, an ozone-depleting substance. A Box-Behnken experimental design was used to generate data from which the oxygen plasma cleaning process could be characterized. Auger electron spectrophotometry was used to measure the contamination thickness on the dice after cleaning. An empirical equation correlating the contamination thickness on the die surface with the operating parameters of the plasma system was developed from the collected Auger data, and optimum settings for cleaning semiconductor devices were determined. Devices were also tested for undesirable changes in electrical parameters resulting from cleaning in the plasma system. An increase in leakage current occurred for bipolar transistors and diodes after exposure to the oxygen plasma. Although an increase in leakage current occurred, each device`s parameter remained well below the acceptable specification limit. Based upon the experimental results, the optimum settings for the plasma cleaning process were determined to be 200 watts of power applied for five minutes in an enclosure maintained at 0.7 torr. At these settings, all measurable contamination was removed without compromising the reliability of the devices.

  9. Role of plasma activation in the kinetics of CNT growth in PECVD process

    NASA Astrophysics Data System (ADS)

    Lebedeva, Irina; Gavrikov, Alexey; Baranov, Alexey; Belov, Maxim; Knizhnik, Andrey; Potapkin, Boris; Sommerer, Timothy

    2009-10-01

    The work presents kinetic modeling of the effect of acceleration for the growth kinetics of carbon nanotubes by hydrocarbon gas mixture modification with plasma discharge. The plasma activation creates active species in hydrocarbon gas mixture, which can easily adsorb and dissociate on the catalyst surface. So plasma treatment of the gas mixture in the CVD process allows to increase the carbon supply rate by a few orders of magnitude compared to that in thermal CVD process. On the other hand, plasma can also provide etching of carbon species from the catalyst surface. To correctly reproduce both of these effects of plasma, the kinetic model of growth of carbon nanotubes is developed based on first-principles analysis of heterogeneous processes on the catalyst surface and detailed kinetics of gas phase chemistry. The model is used to compare the growth rates of carbon nanotubes in thermal and plasma-enhanced CVD processes and to determine critical gas pressures, at which CNT growth kinetics switches from the adsorption limitation to the limitation by reaction and diffusion on the catalyst.

  10. Quench anaylsis of MICE spectrometer superconducting solenoid

    SciTech Connect

    Kashikhin, Vladimir; Bross, Alan; Prestemon, Soren; / /LBL, Berkeley

    2011-09-01

    MICE superconducting spectrometer solenoids fabrication and tests are in progress now. First tests of the Spectrometer Solenoid discovered some issues which could be related to the chosen passive quench protection system. Both solenoids do not have heaters and quench propagation relied on the 'quench back' effect, cold diodes, and shunt resistors. The solenoids have very large inductances and stored energy which is 100% dissipated in the cold mass during a quench. This makes their protection a challenging task. The paper presents the quench analysis of these solenoids based on 3D FEA solution of coupled transient electromagnetic and thermal problems. The simulations used the Vector Fields QUENCH code. It is shown that in some quench scenarios, the quench propagation is relatively slow and some areas can be overheated. They describe ways of improving the solenoids quench protection in order to reduce the risk of possible failure.

  11. Correlations between plasma variables and the deposition process of Si films from chlorosilanes in low pressure RF plasma of argon and hydrogen

    NASA Technical Reports Server (NTRS)

    Avni, R.; Carmi, U.; Grill, A.; Manory, R.; Grossman, E.

    1984-01-01

    The dissociation of chlorosilanes to silicon and its deposition on a solid substrate in a RF plasma of mixtures of argon and hydrogen were investigated as a function of the macrovariables of the plasma. The dissociation mechanism of chlorosilanes and HCl as well as the formation of Si in the plasma state were studied by sampling the plasma with a quadrupole mass spectrometer. Macrovariables such as pressure, net RF power input and locations in the plasma reactor strongly influence the kinetics of dissociation. The deposition process of microcrystalline silicon films and its chlorine contamination were correlated to the dissociation mechanism of chlorosilanes and HCl.

  12. Synthesis of Core-shell Structured Amorphous Si Nanoparticles by Induction Thermal Plasmas

    NASA Astrophysics Data System (ADS)

    Okamoto, Daisuke; Kageyama, Takuya; Tanaka, Manabu; Sone, Hirotaka; Watanabe, Takayuki

    2015-09-01

    Core-shell structured amorphous Si nanoparticles were synthesized by induction thermal plasma. Crystalline Si powder with 3 μm of average diameter was injected into the induction thermal plasma at 4 MHz. The Si raw materials immediately evaporate in the high temperature plasma region and nanoparticles were produced through the quenching process. Counterflow quenching gas was injected from downstream of the torch with its direction against the plasma flow. The effect of the operating parameter such as flow rate of quenching gas and input power was investigated. Collected particles were characterized by X-ray diffraction, transmission electron microscopy, electron energy-loss spectroscopy, and Raman spectroscopy. Obtained results indicate that amorphization degree of the synthesized nanoparticles is more than 90% when additional quenching gas of 20 L/min is injected. The quenching rate of the prepared nanoparticles in the growth region have an important role on determining the amorphization degree. Moreover, EELS and Raman analyses showed the synthesized nanoparticles were coated by the SiO2 shell with thickness of 2-4 nm. These findings indicated that amorphous Si/SiO2 core-shell structured nanoparticles were successfully synthesized by induction thermal plasma in single step.

  13. Novel ArF photoresist polymer to suppress the roughness formation in plasma etching processes

    NASA Astrophysics Data System (ADS)

    Kato, Keisuke; Yasuda, Atsushi; Maeda, Shin-ichi; Uesugi, Takuji; Okada, Takeru; Wada, Akira; Samukawa, Seiji

    2013-03-01

    The serious problem associated with 193-nm lithography using an ArF photoresist is roughness formation of photoresist polymer during plasma processes. We have previously investigated the mechanism of roughness formation caused by plasma. The main deciding factor for roughness formation is a chemical reaction between photoresist polymer and reactive species from plasma. The lactone group in photoresist polymer is highly chemically reactive, and shrinking the lactone structure enhances the roughness formation. In this paper, on the basis of the mechanism of roughness formation, we propose a novel ArF photoresist polymer. The roughness formation was much more suppressed in the novel photoresist polymer during plasma etching process than in the previous type. In the novel photoresist polymer, chemical reactions were spread evenly on the photoresist film surface by adding the polar structure. As a result, decreases in the lactone group were inhibited, leading to suppressing ArF photoresist roughness.

  14. Preparation of silicate tungsten bronzes on aluminum by plasma electrolytic oxidation process in 12-tungstosilicic acid

    NASA Astrophysics Data System (ADS)

    Petković, M.; Stojadinović, S.; Vasilić, R.; Belča, I.; Nedić, Z.; Kasalica, B.; Mioč, U. B.

    2011-09-01

    The growth of silicate tungsten bronzes on aluminum by plasma electrolytic oxidation in 12-tungstosilicic acid is experimentally investigated and discussed. Real time imaging and optical emission spectroscopy characterization of plasma electrolytic oxidation show that spatial density of microdischarges is the highest in the early stage of the process, while the percentage of oxide coating area covered by active discharge sites decreases slowly with time. Emission spectrum of microdischarges has several intensive band peaks originating either from aluminum electrode or from the electrolyte. Surface roughness of obtained oxide coatings increases with prolonged time of plasma electrolytic oxidation, as their microhardness decreases. Raman spectroscopy and energy dispersive X-ray spectroscopy are employed to confirm that the outer layer of oxide coatings formed during the plasma electrolytic oxidation process is silicate tungsten bronze

  15. Bioactive Glass-Ceramic Coatings Synthesized by the Liquid Precursor Plasma Spraying Process

    NASA Astrophysics Data System (ADS)

    Xiao, Yanfeng; Song, Lei; Liu, Xiaoguang; Huang, Yi; Huang, Tao; Chen, Jiyong; Wu, Yao; Wu, Fang

    2011-03-01

    In this study, the liquid precursor plasma spraying process was used to manufacture P2O5-Na2O-CaO-SiO2 bioactive glass-ceramic coatings (BGCCs), where sol and suspension were used as feedstocks for plasma spraying. The effect of precursor and spray parameters on the formation and crystallinity of BGCCs was systematically studied. The results indicated that coatings with higher crystallinity were obtained using the sol precursor, while nanostructured coatings predominantly consisting of amorphous phase were synthesized using the suspension precursor. For coatings manufactured from suspension, the fraction of the amorphous phase increased with the increase in plasma power and the decrease in liquid precursor feed rate. The coatings synthesized from the suspension plasma spray process also showed a good in vitro bioactivity, as suggested by the fast apatite formation when soaking into SBF.

  16. Study of the near-electrode processes in quasi-steady plasma accelerators with impenetrable electrodes

    SciTech Connect

    Kozlov, A. N.

    2012-01-15

    Near-electrode processes in a coaxial plasma accelerator with equipotential impenetrable electrodes are simulated using a two-dimensional (generally, time-dependent) two-fluid MHD model with allowance for the Hall effect and the plasma conductivity tensor. The simulations confirm the theoretically predicted mechanism of the so-called 'crisis of current' caused by the Hall effect. The simulation results are compared with available experimental data. The influence of both the method of plasma supply to the channel and an additional longitudinal magnetic field on the development of near-electrode instabilities preceding the crisis of current is studied.

  17. A high-speed photoresist removal process using multibubble microwave plasma under a mixture of multiphase plasma environment

    SciTech Connect

    Ishijima, Tatsuo; Nosaka, Kohei; Tanaka, Yasunori; Uesugi, Yoshihiko; Goto, Yousuke; Horibe, Hideo

    2013-09-30

    This paper proposes a photoresist removal process that uses multibubble microwave plasma produced in ultrapure water. A non-implanted photoresist and various kinds of ion-implanted photoresists such as B, P, and As were treated with a high ion dose of 5 × 10{sup 15} atoms/cm{sup 2} at an acceleration energy of 70 keV; this resulted in fast removal rates of more than 1 μm/min. When the distance between multibubble microwave plasma and the photoresist film was increased by a few millimeters, the photoresist removal rates drastically decreased; this suggests that short-lived radicals such as OH affect high-speed photoresist removal.

  18. Quantifying the dynamic fluorescence quenching of phenanthrene and ofloxacin by dissolved humic acids.

    PubMed

    Wang, Lin; Liang, Ni; Li, Hao; Yang, Yu; Zhang, Di; Liao, Shaohua; Pan, Bo

    2015-01-01

    Fluorescence quenching includes dynamic and static quenching, and both processes can alter the behavior and reactivity of the fluorescer. However, dynamic quenching is seldom quantified. This study combined dialysis equilibrium and fluorescence quenching methods to compare the contribution of dynamic and static quenching. The results indicate that phenanthrene (PHE)-DHA binding increased with DHA hydrophobicity, while ofloxacin (OFL)-DHA interaction showed the opposite effect. For PHE,the contribution of dynamic quenching to the overall fluorescence quenching was in the range of 50%~82% and decreased to 11%~58% with increased DHA hydrophobicity. However, OFL dynamic quenching increased from 2%~27% to 31%~61% with DHA hydrophobicity. Combining the results using model chemicals, we concluded that the carboxyl groups in DHA might be the primary components for PHE dynamic quenching and might be responsible for both dynamic and static quenching of OFL. Extensive study is needed to explore the quantitative relationship of dynamic quenching and chemical/DHA properties.

  19. ECR plasma cleaning: an in-situ processing technique for RF cavities

    SciTech Connect

    Wu, G.; Moeller, W-D.; Antoine, C.; Jiang, H.; Pechenezhskiy, I.; Cooley, L.; Khabiboulline, T.; Terechkine, Y.; Edwards, H.; Koeth, T.; Romanenko, A.; /Cornell U., Phys. Dept. /Jefferson Lab

    2008-01-01

    A condition for Electron Cyclotron Resonance (ECR) can be established inside a fully assembled RF cavity without the need for removing high-power couplers. As such, plasma generated by this process can be used as a final cleaning step, or as an alternative cleaning step in place of other techniques. Tests showed filtered dry air plasma can successfully remove sulfur particles on niobium surface while the surface oxygen content remains intact.

  20. PREFACE: 12th High-Tech Plasma Processes Conference (HTPP-12)

    NASA Astrophysics Data System (ADS)

    Gleizes, Alain; Ghedini, Emanuele; Gherardi, Matteo; Sanibondi, Paolo; Dilecce, Giorgio

    2012-12-01

    The High-Tech Plasma Processes - 12th European Plasma Conference (HTPP-12) was held in Bologna (Italy) on 24-29 June 2012. The conference series started in 1990 as a thermal plasma conference and gradually expanded to include other topic fields as well. Now the High-Tech Plasma Processes - European Plasma Conference (HTPP) is a bi-annual international conference based in Europe with topics encompassing the whole area of plasma processing science. The aim of the conference is to bring different scientific communities together, facilitate the contacts between science, technology and industry and provide a platform for the exploration of both fundamental topics and new applications of plasmas. Thanks to the efforts of the conference chairman, Professor Vittorio Colombo and of the co-chair, Professor Piero Favia, a well balanced participation from both the communities of thermal and nonthermal plasma researchers was achieved; this resulted in just about 196 attendees from 39 countries, with 8 plenary and 15 invited talks, plus 50 oral and 140 poster contributions. This volume of Journal of Physics: Conference Series gathers papers from regular contributions of HTPP-12; each contribution submitted for publication has been peer reviewed and the Editors are very grateful to the referees for their careful support in improving the original manuscripts. In the end, 39 manuscripts were accepted for publication, covering different topics of plasma processing science: from plasma fundamentals and modelling to source design and process diagnostics, from nanomaterial synthesis to surface modification, from waste treatment to plasma applications in a liquid environment. It is an honour to present this volume of Journal of Physics: Conference Series and we deeply thank the authors for their enthusiastic and high-grade contribution. Finally, we would like to thank the conference chairmen, the members of the steering committee, the international scientific committee, the local

  1. Atomizer with liquid spray quenching

    DOEpatents

    Anderson, I.E.; Osborne, M.G.; Terpstra, R.L.

    1998-04-14

    Method and apparatus are disclosed for making metallic powder particles wherein a metallic melt is atomized by a rotating disk or other atomizer at an atomizing location in a manner to form molten droplets moving in a direction away from said atomizing location. The atomized droplets pass through a series of thin liquid quenching sheets disposed in succession about the atomizing location with each successive quenching sheet being at an increasing distance from the atomizing location. The atomized droplets are incrementally cooled and optionally passivated as they pass through the series of liquid quenching sheets without distorting the atomized droplets from their generally spherical shape. The atomized, cooled droplets can be received in a chamber having a collection wall disposed outwardly of the series of liquid quenching sheets. A liquid quenchant can be flowed proximate the chamber wall to carry the cooled atomized droplets to a collection chamber where atomized powder particles and the liquid quenchant are separated such that the liquid quenchant can be recycled. 6 figs.

  2. Atomizer with liquid spray quenching

    DOEpatents

    Anderson, Iver E.; Osborne, Matthew G.; Terpstra, Robert L.

    1998-04-14

    Method and apparatus for making metallic powder particles wherein a metallic melt is atomized by a rotating disk or other atomizer at an atomizing location in a manner to form molten droplets moving in a direction away from said atomizing location. The atomized droplets pass through a series of thin liquid quenching sheets disposed in succession about the atomizing location with each successive quenching sheet being at an increasing distance from the atomizing location. The atomized droplets are incrementally cooled and optionally passivated as they pass through the series of liquid quenching sheets without distorting the atomized droplets from their generally spherical shape. The atomized, cooled droplets can be received in a chamber having a collection wall disposed outwardly of the series of liquid quenching sheets. A liquid quenchant can be flowed proximate the chamber wall to carry the cooled atomized droplets to a collection chamber where atomized powder particles and the liquid quenchant are separated such that the liquid quenchant can be recycled.

  3. Plasma monitoring and PECVD process control in thin film silicon-based solar cell manufacturing

    NASA Astrophysics Data System (ADS)

    Gabriel, Onno; Kirner, Simon; Klick, Michael; Stannowski, Bernd; Schlatmann, Rutger

    2014-02-01

    A key process in thin film silicon-based solar cell manufacturing is plasma enhanced chemical vapor deposition (PECVD) of the active layers. The deposition process can be monitored in situ by plasma diagnostics. Three types of complementary diagnostics, namely optical emission spectroscopy, mass spectrometry and non-linear extended electron dynamics are applied to an industrial-type PECVD reactor. We investigated the influence of substrate and chamber wall temperature and chamber history on the PECVD process. The impact of chamber wall conditioning on the solar cell performance is demonstrated.

  4. Rapid Fabrication of Lightweight SiC Optics using Reactive Atom Plasma (RAP) Processing

    NASA Technical Reports Server (NTRS)

    Fiske, Peter S.

    2006-01-01

    Reactive Atom Plasma (RAP) processing is a non-contact, plasma-based processing technology that can be used to generate damage-free optical surfaces. We have developed tools and processes using RAP that allow us to shape extremely lightweight mirror Surfaces made from extremely hard-to-machine materials (e.g. SiC). We will describe our latest results using RAP in combination with other technologies to produce finished lightweight SiC mirrors and also discuss applications for RAP in the rapid fabrication of mirror segments for reflective and grazing incidence telescopes.

  5. Chiral logarithms in quenched QCD

    SciTech Connect

    Y. Chen; S. J. Dong; T. Draper; I. Horvath; F. X. Lee; K. F. Liu; N. Mathur; and J. B. Zhang

    2004-08-01

    The quenched chiral logarithms are examined on a 163x28 lattice with Iwasaki gauge action and overlap fermions. The pion decay constant fpi is used to set the lattice spacing, a = 0.200(3) fm. With pion mass as low as {approx}180 MeV, we see the quenched chiral logarithms clearly in mpi2/m and fP, the pseudoscalar decay constant. The authors analyze the data to determine how low the pion mass needs to be in order for the quenched one-loop chiral perturbation theory (chiPT) to apply. With the constrained curve-fitting method, they are able to extract the quenched chiral logarithmic parameter delta together with other low-energy parameters. Only for mpi<=300 MeV do we obtain a consistent and stable fit with a constant delta which they determine to be 0.24(3)(4) (at the chiral scale Lambdachi = 0.8 GeV). By comparing to the 123x28 lattice, they estimate the finite volume effect to be about 2.7% for the smallest pion mass. They also fitted the pion mass to the form for the re-summed cactus diagrams and found that its applicable region is extended farther than the range for the one-loop formula, perhaps up to mpi {approx}500-600 MeV. The scale independent delta is determined to be 0.20(3) in this case. The authors study the quenched non-analytic terms in the nucleon mass and find that the coefficient C1/2 in the nucleon mass is consistent with the prediction of one-loop chiPT. They also obtain the low energy constant L5 from fpi. They conclude from this study that it is imperative to cover only the range of data with the pion mass less than {approx}300 MeV in order to examine the chiral behavior of the hadron masses and decay constants in quenched QCD and match them with quenched one-loop chiPT.

  6. Flexible system for multiple plasma immersion ion implantation-deposition processes

    NASA Astrophysics Data System (ADS)

    Tian, Xiubo; Fu, Ricky K. Y.; Chu, Paul K.; Anders, Andre; Gong, Chunzhi; Yang, Shiqin

    2003-12-01

    Multiple plasma immersion ion implantation-deposition offers better flexibility compared to other thin film deposition techniques with regard to process optimization. The plasmas may be based on either cathodic arc plasmas (metal ions) or gas plasmas (gas ions) or both of them. Processing parameters such as pulsing frequency, pulse duration, bias voltage amplitude, and so on, that critically affect the film structure, internal stress, surface morphology, and other surface properties can be adjusted relatively easily to optimize the process. The plasma density can be readily controlled via the input power to obtain the desirable gas-to-metal ion ratios in the films. The high-voltage pulses can be applied to the samples within (in-duration mode), before (before-duration mode), or after (after-duration mode) the firing of the cathodic arcs. Consequently, dynamic ion beam assisted deposition processes incorporating various mixes of gas and metal ions can be achieved to yield thin films with the desirable properties. The immersion configuration provides to a certain degree the ability to treat components that are large and possess irregular geometries without resorting to complex sample manipulation or beam scanning. In this article we describe the hardware functions of such a system, voltage-current behavior to satisfy the needs of different processes, as well as typical experimental results.

  7. Quenching histories of galaxies and the role of AGN feedback

    NASA Astrophysics Data System (ADS)

    Smethurst, Rebecca Jane; Lintott, Chris; Simmons, Brooke; Galaxy Zoo Team

    2016-01-01

    Two open issues in modern astrophysics are: (i) how do galaxies fully quench their star formation and (ii) how is this affected - or not - by AGN feedback? I present the results of a new Bayesian-MCMC analysis of the star formation histories of over 126,000 galaxies across the colour magnitude diagram showing that diverse quenching mechanisms are instrumental in the formation of the present day red sequence. Using classifications from Galaxy Zoo we show that the rate at which quenching can occur is morphologically dependent in each of the blue cloud, green valley and red sequence. We discuss the nature of these possible quenching mechanisms, considering the influence of secular evolution, galaxy interactions and mergers, both with and without black hole activity. We focus particularly on the relationship between these quenched star formation histories and the presence of an AGN by using this new Bayesian method to show a population of type 2 AGN host galaxies have recently (within 2 Gyr) undergone a rapid (τ < 1 Gyr) drop in their star formation rate. With this result we therefore present the first statistically supported observational evidence that AGN feedback is an important mechanism for the cessation of star formation in this population of galaxies. The diversity of this new method also highlights that such rapid quenching histories cannot account fully for all the quenching across the current AGN host population. We demonstrate that slower (τ > 2 Gyr) quenching rates dominate for high stellar mass (log10[M*/M⊙] > 10.75) hosts of AGN with both early- and late-type morphology. We discuss how these results show that both merger-driven and non-merger processes are contributing to the co-evolution of galaxies and supermassive black holes across the entirety of the colour magnitude diagram.

  8. Satellite Quenching and the Lifecycle of Dwarf Galaxies.

    NASA Astrophysics Data System (ADS)

    Slater, Colin; Bell, Eric F.

    2015-01-01

    In the past ten years the known population of Local Group dwarf galaxies has expanded substantially, both to greater distances from the Milky Way and to lower dwarf masses. This growing sample allows us to study the dwarf system as a population, and ask if we can see in aggregate the signs of processes that would otherwise be difficult to trace in dwarfs individually. Following this strategy I will discuss how the quenching of dwarf galaxies can be modeled and understood at the population-level, and how we use that to constrain how possible quenching mechanisms must work if they are to reproduce the Local Group system that we see. I show that the distribution of quenched satellites can be reproduced by environmental quenching if and only if a single pericenter passage is sufficient to end star formation in low mass dwarfs. I also show that there is a significant transition in the effectiveness of quenching between low mass dwarfs and dwarfs at Magellanic cloud-like masses, with the higher mass dwarfs much more resilient to quenching. I present both ram pressure and delay time models to try to understand the origin of this transition.

  9. Quench Crack Behavior of Nickel-base Disk Superalloys

    NASA Technical Reports Server (NTRS)

    Gayda, John; Kantzos, Pete; Miller, Jason

    2002-01-01

    There is a need to increase the temperature capability of superalloy turbine disks to allow higher operating temperatures in advanced aircraft engines. When modifying processing and chemistry of disk alloys to achieve this capability, it is important to preserve the ability to use rapid cooling during supersolvus heat treatments to achieve coarse grain, fine gamma prime microstructures. An important step in this effort is an understanding of the key variables controlling the cracking tendencies of nickel-base disk alloys during quenching from supersolvus heat treatments. The objective of this study was to investigate the quench cracking tendencies of several advanced disk superalloys during simulated heat treatments. Miniature disk specimens were rapidly quenched after solution heat treatments. The responses and failure modes were compared and related to the quench cracking tendencies of actual disk forgings. Cracking along grain boundaries was generally observed to be operative. For the alloys examined in this study, the solution temperature not alloy chemistry was found to be the primary factor controlling quench cracking. Alloys with high solvus temperatures show greater tendency for quench cracking.

  10. NASA MSFC Electrostatic Levitator (ESL) Rapid Quench System

    NASA Technical Reports Server (NTRS)

    SanSoucie, Michael P.; Craven, Paul D.

    2014-01-01

    Electrostatic levitation, a form of containerless processing, is an important tool in materials research. Levitated specimens are free from contact with a container; therefore, heterogeneous nucleation on container walls is not possible. This allows studies of deeply undercooled melts. Furthermore, studies of high-temperature, highly reactive materials are also possible. Studies of the solidification and crystallization of undercooled melts is vital to the understanding of microstructure development, particularly the formation of alloys with unique properties by rapid solidification. The NASA Marshall Space Flight Center (MSFC) Electrostatic Levitator (ESL) lab has recently been upgraded to allow for rapid quenching of levitated materials. The ESL Rapid Quench System uses a small crucible-like vessel that can be partially filled with a low melting point material, such as a Gallium alloy, as a quench medium. An undercooled sample can be dropped into the vessel to rapidly quench the sample. A carousel with nine vessels sits below the bottom electrode assembly. This system allows up to nine rapid quenches before having to break vacuum and remove the vessels. This new Rapid Quench System will allow materials science studies of undercooled materials and new materials development. In this presentation, the system is described and initial results are presented.

  11. Coupled transient thermal and electromagnetic finite element analysis of quench in MICE coupling magnet

    NASA Astrophysics Data System (ADS)

    Guo, X. L.; Wang, L.; Green, M. A.

    2012-07-01

    The superconducting coupling magnet used for the international Muon Ionization Cooling Experiment (MICE) will be passively protected through coil subdivision and quench back simultaneously. The design of such type quench protection system requires detailedly understanding of the heat transfer and electromagnetic process in the magnet during quench process. A coupled transient thermal and electromagnetic finite element model was developed to study the quench process of the coupling magnet. This model sequentially solves two different physics environments, one is thermal physics environment and the other one is coupled-electromagnetic-circuit physics environment. The two environments are coupled by applying results from one environment as loads in another one. The results such as current, hot spot temperature, resistance and over voltage during quench process are presented. The results of this model were compared with that of a semi-empirical model, and the respective advantages of both models were pointed out. The quench propagation process in the coupling magnet and the effect of the quench back on the speeding up the quench process were analyzed. The goal of such work is to predict the quench evolution of the coupling magnet in detail and guide its protection scheme.

  12. Rapid-quench axially staged combustor

    SciTech Connect

    Feitelberg, Alan S.; Schmidt, Mark Christopher; Goebel, Steven George

    1999-01-01

    A combustor cooperating with a compressor in driving a gas turbine includes a cylindrical outer combustor casing. A combustion liner, having an upstream rich section, a quench section and a downstream lean section, is disposed within the outer combustor casing defining a combustion chamber having at least a core quench region and an outer quench region. A first plurality of quench holes are disposed within the liner at the quench section having a first diameter to provide cooling jet penetration to the core region of the quench section of the combustion chamber. A second plurality of quench holes are disposed within the liner at the quench section having a second diameter to provide cooling jet penetration to the outer region of the quench section of the combustion chamber. In an alternative embodiment, the combustion chamber quench section further includes at least one middle region and at least a third plurality of quench holes disposed within the liner at the quench section having a third diameter to provide cooling jet penetration to at least one middle region of the quench section of the combustion chamber.

  13. Physical processes in the plasma mantle of Venus

    NASA Technical Reports Server (NTRS)

    Szego, K.; Shapiro, V. S.; Shevchenko, V. I.; Sagdeev, R. Z.; Kasprzak, W. T.; Nagy, A. F.

    1991-01-01

    The results are presented of a study, which analyzed data from 10 Pioneer Venus orbits in order to see whether similar wave particle interaction processes also exist in the corresponding region around Venus. The first conclusion is that the apparent physical processes in the mantle are indeed similar around Venus and Mars. The planetary thermal O(+) ions outside the ionopause interact with the shocked solar wind and excite electrostatic waves close to the lower hybrid frequency. These waves propagate inwards, heating first the electron and deeper down in the ionosphere the thermal ion population. The observed superthermal ions are believed to be the product of this wave particle interaction process. It is also concluded that the wave energy transferred to the thermal electrons is of the right magnitude (about 4 x 10 exp 9 eV/sq cm s) to provide the supplemental heat source necessary to reconcile observed and calculated electron temperatures in the ionosphere.

  14. Electric and thermal conductivities of quenched neutron star crusts

    NASA Technical Reports Server (NTRS)

    Ogata, Shuji; Ichimaru, Setsuo

    1990-01-01

    The electric and thermal conductivities in the outer crustal matter of a neutron star quenched into a solid state by cooling are estimated using a Monte Carlo simulation of freezing transition for dense plasmas. The conductivities are calculated by the precise evaluation of the scattering integrals, using the procedure of Ichimaru et al. (1983) and Iyetomi and Ichimaru (1983). The results predict the conductivities lower, by a factor of about 3, than those with the single-phonon approximation.

  15. On-line elemental analysis of fossil fuel process streams by inductively coupled plasma spectrometry

    SciTech Connect

    Chisholm, W.P.

    1995-06-01

    METC is continuing development of a real-time, multi-element plasma based spectrometer system for application to high temperature and high pressure fossil fuel process streams. Two versions are under consideration for development. One is an Inductively Coupled Plasma system that has been described previously, and the other is a high power microwave system. The ICP torch operates on a mixture of argon and helium with a conventional annular swirl flow plasma gas, no auxiliary gas, and a conventional sample stream injection through the base of the plasma plume. A new, demountable torch design comprising three ceramic sections allows bolts passing the length of the torch to compress a double O-ring seal. This improves the reliability of the torch. The microwave system will use the same data acquisition and reduction components as the ICP system; only the plasma source itself is different. It will operate with a 750-Watt, 2.45 gigahertz microwave generator. The plasma discharge will be contained within a narrow quartz tube one quarter wavelength from a shorted waveguide termination. The plasma source will be observed via fiber optics and a battery of computer controlled monochromators. To extract more information from the raw spectral data, a neural net computer program is being developed. This program will calculate analyte concentrations from data that includes analyte and interferant spectral emission intensity. Matrix effects and spectral overlaps can be treated more effectively by this method than by conventional spectral analysis.

  16. Plasma Processing of Large Surfaces with Application to SRF Cavity Modification

    SciTech Connect

    Upadhyay, Janardan; Popovic, Svetozar; Vuskovic, Leposova; Im, Do; Valente, Anne-Marie; Phillips, H

    2013-09-01

    Plasma based surface modifications of SRF cavities present promising alternatives to the wet etching technology currently applied. To understand and characterize the plasma properties and chemical kinetics of plasma etching processes inside a single cell cavity, we have built a specially-designed cylindrical cavity with 8 observation ports. These ports can be used for holding niobium samples and diagnostic purposes simultaneously. Two frequencies (13.56 MHz and 2.45 GHz) of power source are used for different pressure, power and gas compositions. The plasma parameters were evaluated by a Langmuir probe and by an optical emission spectroscopy technique based on the relative intensity of two Ar 5p-4s lines at 419.8 and 420.07 nm. Argon 5p-4s transition is chosen to determine electron temperature in order to optimize parameters for plasma processing. Chemical kinetics of the process was observed using real-time mass spectroscopy. The effect of these parameters on niobium surface would be measured, presented at this conference, and used as guidelines for optimal design of SRF etching process.

  17. Freeze-drying process monitoring using a cold plasma ionization device.

    PubMed

    Mayeresse, Y; Veillon, R; Sibille, P H; Nomine, C

    2007-01-01

    A cold plasma ionization device has been designed to monitor freeze-drying processes in situ by monitoring lyophilization chamber moisture content. This plasma device, which consists of a probe that can be mounted directly on the lyophilization chamber, depends upon the ionization of nitrogen and water molecules using a radiofrequency generator and spectrometric signal collection. The study performed on this probe shows that it is steam sterilizable, simple to integrate, reproducible, and sensitive. The limitations include suitable positioning in the lyophilization chamber, calibration, and signal integration. Sensitivity was evaluated in relation to the quantity of vials and the probe positioning, and correlation with existing methods, such as microbalance, was established. These tests verified signal reproducibility through three freeze-drying cycles. Scaling-up studies demonstrated a similar product signature for the same product using pilot-scale and larger-scale equipment. On an industrial scale, the method efficiently monitored the freeze-drying cycle, but in a larger industrial freeze-dryer the signal was slightly modified. This was mainly due to the positioning of the plasma device, in relation to the vapor flow pathway, which is not necessarily homogeneous within the freeze-drying chamber. The plasma tool is a relevant method for monitoring freeze-drying processes and may in the future allow the verification of current thermodynamic freeze-drying models. This plasma technique may ultimately represent a process analytical technology (PAT) approach for the freeze-drying process. PMID:17722483

  18. Fundamental studies of the plasma extraction and ion beam formation processes in inductively coupled plasma mass spectrometry

    SciTech Connect

    Niu, Hongsen

    1995-02-10

    The fundamental and practical aspects are described for extracting ions from atmospheric pressure plasma sources into an analytical mass spectrometer. Methodologies and basic concepts of inductively coupled plasma mass spectrometry (ICP-MS) are emphasized in the discussion, including ion source, sampling interface, supersonic expansion, slumming process, ion optics and beam focusing, and vacuum considerations. Some new developments and innovative designs are introduced. The plasma extraction process in ICP-MS was investigated by Langmuir measurements in the region between the skimmer and first ion lens. Electron temperature (T{sub e}) is in the range 2000--11000 K and changes with probe position inside an aerosol gas flow. Electron density (n{sub e}) is in the range 10{sup 8}--10{sup 10} {sup {minus}cm }at the skimmer tip and drops abruptly to 10{sup 6}--10{sup 8} cm{sup {minus}3} near the skimmer tip and drops abruptly to 10{sup 6}--10{sup 8} cm{sup {minus}3} downstream further behind the skimmer. Electron density in the beam leaving the skimmer also depends on water loading and on the presence and mass of matrix elements. Axially resolved distributions of electron number-density and electron temperature were obtained to characterize the ion beam at a variety of plasma operating conditions. The electron density dropped by a factor of 101 along the centerline between the sampler and skimmer cones in the first stage and continued to drop by factors of 10{sup 4}--10{sup 5} downstream of skimmer to the entrance of ion lens. The electron density in the beam expansion behind sampler cone exhibited a 1/z{sup 2} intensity fall-off (z is the axial position). An second beam expansion originated from the skimmer entrance, and the beam flow underwent with another 1/z{sup 2} fall-off behind the skimmer. Skimmer interactions play an important role in plasma extraction in the ICP-MS instrument.

  19. Physicochemical processes in the indirect interaction between surface air plasma and deionized water

    NASA Astrophysics Data System (ADS)

    Liu, Z. C.; Liu, D. X.; Chen, C.; Li, D.; Yang, A. J.; Rong, M. Z.; Chen, H. L.; Kong, M. G.

    2015-12-01

    One of the most central scientific questions for plasma applications in healthcare and environmental remediation is the chemical identity and the dose profile of plasma-induced reactive oxygen and nitrogen species (ROS/RNS) that can act on an object inside a liquid. A logical focus is on aqueous physicochemical processes near a sample with a direct link to their upstream gaseous processes in the plasma region and a separation gap from the liquid bulk. Here, a system-level modeling framework is developed for indirect interactions of surface air plasma and a deionized water bulk and its predictions are found to be in good agreement with the measurement of gas-phase ozone and aqueous long-living ROS/RNS concentrations. The plasma region is described with a global model, whereas the air gap and the liquid region are simulated with a 1D fluid model. All three regions are treated as one integrated entity and computed simultaneously. With experimental validation, the system-level modeling shows that the dominant aqueous ROS/RNS are long-living species (e.g. H2O2 aq, O3 aq, nitrite/nitrate, H+ aq). While most short-living gaseous species could hardly survive their passage to the liquid, aqueous short-living ROS/RNS are generated in situ through reactions among long-living plasma species and with water molecules. This plasma-mediated remote production of aqueous ROS/RNS is important for the abundance of aqueous HO2 aq, HO3 aq, OHaq and \\text{O}2- aq as well as NO2 aq and NO3 aq. Aqueous plasma chemistry offers a novel and significant pathway to activate a given biological outcome, as exemplified here for bacterial deactivation in plasma-activated water. Additional factors that may synergistically broaden the usefulness of aqueous plasma chemistry include an electric field by aqueous ions and liquid acidification. The system-modeling framework will be useful in assisting designs and analyses of future investigations of plasma-liquid and plasma-cell interactions.

  20. Opinion on the use of plasma processes for treatment of foods.

    PubMed

    Schlüter, Oliver; Ehlbeck, Jörg; Hertel, Christian; Habermeyer, Michael; Roth, Angelika; Engel, Karl-Heinz; Holzhauser, Thomas; Knorr, Dietrich; Eisenbrand, Gerhard

    2013-05-01

    The working group "Food technology and safety" of the DFG Senate Commission on Food Safety (SKLM) advises on new technologies concerning food processing. Treatment with plasma is a newly developed process, which is currently used only on a pilot scale in Europe. The novel plasma treatment technology is experimentally applied to consumer goods. There are also potential applications in the food sector, e.g. to inactivate microorganisms on food surfaces. There is still insufficient information on concomitant physical and chemical processes and changes induced in the food. On May 25th 2012, the SKLM issued a first statement on plasma treatment of foods in German. The English version was agreed on December 14th 2012.

  1. Using indium tin oxide material to implement the imaging of microwave plasma ignition process

    SciTech Connect

    Wang, Qiang; Hou, Lingyun; Zhang, Guixin Zhang, Boya; Liu, Cheng; Wang, Zhi; Huang, Jian

    2014-02-17

    In this paper, a method is introduced to get global observation of microwave plasma ignition process at high pressure. A microwave resonator was designed with an indium tin oxide coated glass at bottom. Microwave plasma ignition was implemented in methane and air mixture at 10 bars by a 2 ms-3 kW-2.45 GHz microwave pulse, and the high speed images of the ignition process were obtained. The images visually proved that microwave plasma ignition could lead to a multi-point ignition. The system may also be applied to obtain Schlieren images, which is commonly used to observe the development of flame kernel in an ignition process.

  2. Real-time dielectric-film thickness measurement system for plasma processing chamber wall monitoring.

    PubMed

    Kim, Jin-Yong; Chung, Chin-Wook

    2015-12-01

    An in-situ real-time processing chamber wall monitoring system was developed. In order to measure the thickness of the dielectric film, two frequencies of small sinusoidal voltage (∼1 V) signals were applied to an electrically floated planar type probe, which is positioned at chamber wall surface, and the amplitudes of the currents and the phase differences between the voltage and current were measured. By using an equivalent sheath circuit model including a sheath capacitance, the dielectric thickness can be obtained. Experiments were performed in various plasma condition, and reliable dielectric film thickness was obtained regardless of the plasma properties. In addition, availability in commercial chamber for plasma enhanced chemical vapor deposition was verified. This study is expected to contribute to the control of etching and deposition processes and optimization of periodic maintenance in semiconductor manufacturing process.

  3. Power supplies and quench protection for the Tokamak Physics Experiment

    SciTech Connect

    Neumeyer, C.L.

    1994-07-01

    The Tokamak Physics Experiment (TPX) is an advanced tokamak project aimed at the production of quasi-steady state plasmas with advanced shape, heating, and particle control. TPX is to be built at the Princeton Plasma Physics Laboratory (PPPL) using many of the facilities from the Tokamak Fusion Test Reactor (TFTR). First plasma is scheduled for the year 2000. TPX will be the first tokamak to utilize superconducting (SC) magnets in both the toroidal field (TF) and poloidal field (PF) systems. This is a new feature which requires not only a departure from the traditional tokamak power supply schemes but also that ultra-reliable quench protection devices be used to rapidly discharge the stored energy from the magnets in the event of a quench. This paper describes the plan and basis for the adaptation and augmentation of the PPPL/TFTR power system facilities to supply TPX. Following a description of the basic operational requirements, four major areas are addressed, namely the AC power system, the TF power supply, the PF power supply, and quench protection for the TF and PF systems.

  4. Particle-In-Cell simulations of high pressure plasmas using graphics processing units

    NASA Astrophysics Data System (ADS)

    Gebhardt, Markus; Atteln, Frank; Brinkmann, Ralf Peter; Mussenbrock, Thomas; Mertmann, Philipp; Awakowicz, Peter

    2009-10-01

    Particle-In-Cell (PIC) simulations are widely used to understand the fundamental phenomena in low-temperature plasmas. Particularly plasmas at very low gas pressures are studied using PIC methods. The inherent drawback of these methods is that they are very time consuming -- certain stability conditions has to be satisfied. This holds even more for the PIC simulation of high pressure plasmas due to the very high collision rates. The simulations take up to very much time to run on standard computers and require the help of computer clusters or super computers. Recent advances in the field of graphics processing units (GPUs) provides every personal computer with a highly parallel multi processor architecture for very little money. This architecture is freely programmable and can be used to implement a wide class of problems. In this paper we present the concepts of a fully parallel PIC simulation of high pressure plasmas using the benefits of GPU programming.

  5. Silicon Wafer Surface-Temperature Monitoring System for Plasma Etching Process

    NASA Astrophysics Data System (ADS)

    Yamada, Y.; Ishii, J.; Nakaoka, A.; Mizojiri, Y.

    2011-08-01

    A thermoreflectance temperature measuring system was developed with the aim to realize monitoring of the silicon wafer surface temperature during plasma etching. The thermoreflectance detects variations in temperature through changes in optical reflectance. To overcome such difficulties as low sensitivity and limitation in installation space and position for in situ measurements, the differential thermoreflectance utilizing two orthogonal polarizations was introduced. Noise such as fluctuations in the incident beam intensity or changes of loss in the optical path would affect both polarizations equally and would not affect the measurement. The large angle of incidence of the beam allows measurement to be performed from outside the viewing ports of existing plasma etching process chambers through the gap between the plasma electrode and the silicon wafer. In this article, an off-line measurement result is presented, with results for bare wafers as well as for wafers with metal depositions. A prototype system developed for tests in plasma etching facilities in a production line is described.

  6. Disentangling fluxes of energy and matter in plasma-surface interactions: Effect of process parameters

    SciTech Connect

    Wolter, M.; Levchenko, I.; Ostrikov, K.; Kersten, H.; Kumar, S.

    2010-09-15

    The possibility to discriminate between the relative importance of the fluxes of energy and matter in plasma-surface interaction is demonstrated by the energy flux measurements in low-temperature plasmas ignited by the radio frequency discharge (power and pressure ranges 50-250 W and 8-11.5 Pa) in Ar, Ar+H{sub 2}, and Ar+H{sub 2}+CH{sub 4} gas mixtures typically used in nanoscale synthesis and processing of silicon- and carbon-based nanostructures. It is shown that by varying the gas composition and pressure, the discharge power, and the surface bias one can effectively control the surface temperature and the matter supply rates. The experimental findings are explained in terms of the plasma-specific reactions in the plasma bulk and on the surface.

  7. Numerical simulation of nonlinear processes in a beam-plasma system

    SciTech Connect

    Efimova, A. A. Berendeev, E. A.; Vshivkov, V. A.; Dudnikova, G. I.

    2015-10-28

    In the present paper we consider the efficiency of the electromagnetic radiation generation due to various nonlinear processes in the beam-plasma system. The beam and plasma parameters were chosen close to the parameters in the experiment on the GOL-3 facility (BINP SB RAS). The model of the collisionless plasma is described by system of the Vlasov-Maxwell equations with periodic boundary conditions. The parallel numerical algorithm is based on the particles-in-cell method (PIC) with mixed Euler-Lagrangian domain decomposition. Various scenarios of nonlinear evolution in the beam-plasma system under the influence of an external magnetic field in case of a low density beam were studied. The energy transfer from one unstable mode to the others modes was observed.

  8. Microwave discharges at low pressures and peculiarities of the processes in strongly non-uniform plasma

    NASA Astrophysics Data System (ADS)

    Lebedev, Yu A.

    2015-10-01

    Microwave discharges (MD) are widely used as a source of non-equilibrium low pressure plasma for different applications. This paper reviews the methods of microwave plasma generation at pressures from 10-2 approximately to 30 kPa with centimeter-millimeter wavelength microwaves on the basis of scientific publications since 1950 up to the present. The review consists of 16 sections. A general look at MDs and their application is given in the introduction, together with a description of a typical block-schema of the microwave plasma generator, classification of MD, and attractive features of MD. Sections 2-12 describe the different methods of microwave plasma generators on the basis of cavity and waveguide discharges, surface and slow wave discharges, discharges with distributed energy input, initiated and surface discharges, discharges in wave beams, discharges with stochastically jumping phases of microwaves, discharges in an external magnetic field and discharges with a combination of microwave field and dc and RF fields. These methods provide the possibility of producing nonequilibriun high density plasma in small and large chambers for many applications. Plasma chemical activity of nonequilibrium microwave plasma is analyzed in section 13. A short consideration of the history and status of the problem is given. The main areas of microwave plasma application are briefly described in section 14. Non-uniformity is the inherent property of the majority of electrical discharges and MDs are no exception. Peculiarities of physical-chemical processes in strongly non-uniform MDs are demonstrated placing high emphasis on the influence of small noble gas additions to the main plasma gas (section 15). The review is illustrated by 80 figures. The list of references contains 350 scientific publications.

  9. Plasma Spray-PVD: A New Thermal Spray Process to Deposit Out of the Vapor Phase

    NASA Astrophysics Data System (ADS)

    von Niessen, Konstantin; Gindrat, Malko

    2011-06-01

    Plasma spray-physical vapor deposition (PS-PVD) is a low pressure plasma spray technology recently developed by Sulzer Metco AG (Switzerland). Even though it is a thermal spray process, it can deposit coatings out of the vapor phase. The basis of PS-PVD is the low pressure plasma spraying (LPPS) technology that has been well established in industry for several years. In comparison to conventional vacuum plasma spraying (VPS) or low pressure plasma spraying (LPPS), the new proposed process uses a high energy plasma gun operated at a reduced work pressure of 0.1 kPa (1 mbar). Owing to the high energy plasma and further reduced work pressure, PS-PVD is able to deposit a coating not only by melting the feed stock material which builds up a layer from liquid splats but also by vaporizing the injected material. Therefore, the PS-PVD process fills the gap between the conventional physical vapor deposition (PVD) technologies and standard thermal spray processes. The possibility to vaporize feedstock material and to produce layers out of the vapor phase results in new and unique coating microstructures. The properties of such coatings are superior to those of thermal spray and electron beam-physical vapor deposition (EB-PVD) coatings. In contrast to EB-PVD, PS-PVD incorporates the vaporized coating material into a supersonic plasma plume. Owing to the forced gas stream of the plasma jet, complex shaped parts such as multi-airfoil turbine vanes can be coated with columnar thermal barrier coatings using PS-PVD. Even shadowed areas and areas which are not in the line of sight of the coating source can be coated homogeneously. This article reports on the progress made by Sulzer Metco in developing a thermal spray process to produce coatings out of the vapor phase. Columnar thermal barrier coatings made of Yttria-stabilized Zircona (YSZ) are optimized to serve in a turbine engine. This process includes not only preferable coating properties such as strain tolerance and erosion

  10. Plasma Processing of SRF Cavities for the next Generation Of Particle Accelerators

    SciTech Connect

    Vuskovic, Leposava

    2015-11-23

    The cost-effective production of high frequency accelerating fields are the foundation for the next generation of particle accelerators. The Ar/Cl2 plasma etching technology holds the promise to yield a major reduction in cavity preparation costs. Plasma-based dry niobium surface treatment provides an excellent opportunity to remove bulk niobium, eliminate surface imperfections, increase cavity quality factor, and bring accelerating fields to higher levels. At the same time, the developed technology will be more environmentally friendly than the hydrogen fluoride-based wet etching technology. Plasma etching of inner surfaces of standard multi-cell SRF cavities is the main goal of this research in order to eliminate contaminants, including niobium oxides, in the penetration depth region. Successful plasma processing of multi-cell cavities will establish this method as a viable technique in the quest for more efficient components of next generation particle accelerators. In this project the single-cell pill box cavity plasma etching system is developed and etching conditions are determined. An actual single cell SRF cavity (1497 MHz) is plasma etched based on the pill box cavity results. The first RF test of this plasma etched cavity at cryogenic temperature is obtained. The system can also be used for other surface modifications, including tailoring niobium surface properties, surface passivation or nitriding for better performance of SRF cavities. The results of this plasma processing technology may be applied to most of the current SRF cavity fabrication projects. In the course of this project it has been demonstrated that a capacitively coupled radio-frequency discharge can be successfully used for etching curved niobium surfaces, in particular the inner walls of SRF cavities. The results could also be applicable to the inner or concave surfaces of any 3D structure other than an SRF cavity.

  11. Spatially resolvable optical emission spectrometer for analyzing density uniformity of semiconductor process plasma

    SciTech Connect

    Oh, Changhoon; Ryoo, Hoonchul; Lee, Hyungwoo; Hahn, Jae W.; Kim, Se-Yeon; Yi, Hun-Jung

    2010-10-15

    We proposed a spatially resolved optical emission spectrometer (SROES) for analyzing the uniformity of plasma density for semiconductor processes. To enhance the spatial resolution of the SROES, we constructed a SROES system using a series of lenses, apertures, and pinholes. We calculated the spatial resolution of the SROES for the variation of pinhole size, and our calculated results were in good agreement with the measured spatial variation of the constructed SROES. The performance of the SROES was also verified by detecting the correlation between the distribution of a fluorine radical in inductively coupled plasma etch process and the etch rate of a SiO{sub 2} film on a silicon wafer.

  12. Synthesis Process of Copper/Graphene Nanocomposite by the Liquid Phase Plasma Reduction Method.

    PubMed

    Kim, Sang-Chai; Park, Young-Kwon; Chung, Minchul; Ahn, Ho-Geun; Lee, Heon; Jung, Sang-Chul

    2016-02-01

    Liquid phase plasma (LPP) process was applied to the impregnation of copper nanoparticles onto graphene sheet. Approximately 30-50 nm sized tetragonal nanoparticles were dispersed uniformly on the surface of the two-dimensional graphene sheet. The amount of copper nanoparticles precipitated increased with increasing LPP process time. When combined with a subsequent process, the synthesized copper/graphene nanocomposites will be able to high-performance Li-ion batteries effectively. PMID:27433733

  13. PARTICIPANT SUPPORT FOR THE 2010 GORDON RESEARCH CONFERENCE ON PLASMA PROCESSING SCIENCE (JULY 11-16,2010)

    SciTech Connect

    Uwe Kortshagen

    2011-06-14

    The 2010 Gordon Research Conference on Plasma Processing Science will feature a comprehensive program that will highlight the most cutting edge scientific advances in low temperature plasma science and will explore the applications of low temperature plasma technology relative to many grand societal challenges. Fundamental science sessions will focus on plasma kinetics, plasma surface interactions, and recent trends in plasma generation and multi-phase plasmas. Application sessions will explore the impact of plasma technology in renewable energy and the production of fuels from renewable feedstocks, plasma-enabled medicine and sterilization, and environmental remediation and waste treatment. The conference will bring together in an informal atmosphere leaders in the field with junior investigators and graduate students. The special format of the Gordon Conferences, with programmed discussion sessions and ample time for informal gatherings in the afternoons and evenings, will provide for a fertile atmosphere of brainstorming and creative thinking among the attendees.

  14. Plasma damage mechanisms for low-k porous SiOCH films due to radiation, radicals, and ions in the plasma etching process

    SciTech Connect

    Uchida, Saburo; Takashima, Seigo; Hori, Masaru; Fukasawa, Masanaga; Ohshima, Keiji; Nagahata, Kazunori; Tatsumi, Tetsuya

    2008-04-01

    Low dielectric constant (low-k) films have been widely used as insulating materials in ultra-large-scale integrated circuits. Low-k films receive heavy damage during the plasma processes of etching or ashing, resulting in an increase in their dielectric constant. In order to realize damage-free plasma processes for low-k films, it is essential to determine the influence of radiation, radicals, and ions emitted in the plasma process on the characteristics of low-k films. We have developed a technique to evaluate the influence of radiation, radicals, ions, and their synergies on films in real plasma processes and have named it pallet for plasma evaluation (PAPE). Using the PAPE, plasma-induced damage on porous SiOCH films were investigated in dual-frequency capacitively coupled H{sub 2}/N{sub 2} plasmas. The damage was characterized by ellipsometry, Fourier-transform infrared spectroscopy, and thermal desorption spectroscopy. On the basis of the results, the damage mechanisms associated with vacuum ultraviolet (VUV) and UV radiation, radicals, and ions were clarified. The damage was caused not only by ions and radicals but also by VUV and UV radiation emitted by the plasmas. Moreover, it was found that the synergy between the radiation and the radicals enhanced the damage.

  15. TASK 2: QUENCH ZONE SIMULATION

    SciTech Connect

    Fusselman, Steve

    2015-09-30

    Aerojet Rocketdyne (AR) has developed an innovative gasifier concept incorporating advanced technologies in ultra-dense phase dry feed system, rapid mix injector, and advanced component cooling to significantly improve gasifier performance, life, and cost compared to commercially available state-of-the-art systems. A key feature of the AR gasifier design is the transition from the gasifier outlet into the quench zone, where the raw syngas is cooled to ~ 400°C by injection and vaporization of atomized water. Earlier pilot plant testing revealed a propensity for the original gasifier outlet design to accumulate slag in the outlet, leading to erratic syngas flow from the outlet. Subsequent design modifications successfully resolved this issue in the pilot plant gasifier. In order to gain greater insight into the physical phenomena occurring within this zone, AR developed a cold flow simulation apparatus with Coanda Research & Development with a high degree of similitude to hot fire conditions with the pilot scale gasifier design, and capable of accommodating a scaled-down quench zone for a demonstration-scale gasifier. The objective of this task was to validate similitude of the cold flow simulation model by comparison of pilot-scale outlet design performance, and to assess demonstration scale gasifier design feasibility from testing of a scaled-down outlet design. Test results did exhibit a strong correspondence with the two pilot scale outlet designs, indicating credible similitude for the cold flow simulation device. Testing of the scaled-down outlet revealed important considerations in the design and operation of the demonstration scale gasifier, in particular pertaining to the relative momentum between the downcoming raw syngas and the sprayed quench water and associated impacts on flow patterns within the quench zone. This report describes key findings from the test program, including assessment of pilot plant configuration simulations relative to actual

  16. Relationship between gas-phase chemistries and surface processes in fluorocarbon etch plasmas: A process rate model

    SciTech Connect

    Sant, S. P.; Nelson, C. T.; Overzet, L. J.; Goeckner, M. J.

    2009-07-15

    In a typical plasma tool, both etch and deposition occur simultaneously. Extensive experimental measurements are used to help develop a general model of etch and deposition processes. This model employs reaction probabilities, or surface averaged cross sections, to link the measurable surface processes, etch and deposition, to the flux of various species to the surfaces. Because the cross sections are quantum mechanical in nature, this surface rate model should be applicable to many low temperature plasma processing systems. Further, the parameters that might be important in reaction cross sections are known from quantum mechanics, e.g., species, energy, temperature, and impact angle. Such parameters might vary from system to system, causing the wide processing variability observed in plasma tools. Finally the model is used to compare measurements of ion flux, ion energy, and fluorocarbon radical flux to the measured process rates. It is found that the model appears to be consistent with calculations of gain/loss rates for the various radicals present in the discharge as well as measured etch and deposition rates.

  17. Method and Process Development of Advanced Atmospheric Plasma Spraying for Thermal Barrier Coatings

    NASA Astrophysics Data System (ADS)

    Mihm, Sebastian; Duda, Thomas; Gruner, Heiko; Thomas, Georg; Dzur, Birger

    2012-06-01

    Over the last few years, global economic growth has triggered a dramatic increase in the demand for resources, resulting in steady rise in prices for energy and raw materials. In the gas turbine manufacturing sector, process optimizations of cost-intensive production steps involve a heightened potential of savings and form the basis for securing future competitive advantages in the market. In this context, the atmospheric plasma spraying (APS) process for thermal barrier coatings (TBC) has been optimized. A constraint for the optimization of the APS coating process is the use of the existing coating equipment. Furthermore, the current coating quality and characteristics must not change so as to avoid new qualification and testing. Using experience in APS and empirically gained data, the process optimization plan included the variation of e.g. the plasma gas composition and flow-rate, the electrical power, the arrangement and angle of the powder injectors in relation to the plasma jet, the grain size distribution of the spray powder and the plasma torch movement procedures such as spray distance, offset and iteration. In particular, plasma properties (enthalpy, velocity and temperature), powder injection conditions (injection point, injection speed, grain size and distribution) and the coating lamination (coating pattern and spraying distance) are examined. The optimized process and resulting coating were compared to the current situation using several diagnostic methods. The improved process significantly reduces costs and achieves the requirement of comparable coating quality. Furthermore, a contribution was made towards better comprehension of the APS of ceramics and the definition of a better method for future process developments.

  18. New chamber walls conditioning and cleaning strategies to improve the stability of plasma processes

    NASA Astrophysics Data System (ADS)

    Cunge, G.; Pelissier, B.; Joubert, O.; Ramos, R.; Maurice, C.

    2005-08-01

    One major challenge in plasma etching processes for integrated circuit fabrication is to achieve a good wafer-to-wafer repeatability. This requires a perfect control of the plasma chamber wall conditions. For silicon etching processes, which deposit SiOyClz layers on the chamber walls, this is achieved by cleaning the interior surfaces of the plasma chamber with an SF6-based plasma after each wafer is etched. However, x-ray photoelectron spectroscopy analysis of the reactor wall surfaces shows that the inner parts of the Al2O3 chamber are strongly fluorinated (formation of Al-F bonds) during the SF6 plasma. At the same time the AlFx layer is sputtered from some parts of the chamber (mostly from the roof, which is bombarded by high energy ions), and AlF redeposition is observed on other parts of the reactor body. Hence, the cleaning process of the reactor leaves AlF residues on the chamber wall on its own. This leads to several issues including flake off of AlxFy particles on the wafer and process drifts (due both to the progressive growth of AlF material on the SiO2 windows and to the release of F atoms from the chamber walls during the etching process). This indicates that a strategy other than dry-cleaning the Al2O3 chamber walls in fluorine-based plasmas should be found. In this paper we have investigated two different strategies. The first one consists of replacing Al2O3 covering the chamber walls by another material for the chamber walls inner coating. In particular, we have investigated the surface modification of several types of organic polymers (Teflon, Parylene and carbon-rich polymers), when exposed to SF6-based plasmas. We show that these materials can be reset to their original condition after exposure to a dry-cleaning process because carbon containing polymers are slowly etched away by the SF6/O2 plasma. This suggests that the replacement of the conventional Al2O3 chamber wall material by a carbon-coated liner should be possible. Alternatively, we

  19. Arc-Plasma Wire Spraying: An Optical Study of Process Phenomenology

    NASA Astrophysics Data System (ADS)

    Gulyaev, I. P.; Dolmatov, A. V.; Kharlamov, M. Yu.; Gulyaev, P. Yu.; Jordan, V. I.; Krivtsun, I. V.; Korzhyk, V. M.; Demyanov, O. I.

    2015-12-01

    In the present paper, we report on the results of an experimental study of heat- and mass-transfer processes in a Plazer 30-PL-W plasma-jet facility used for arc-plasma wire spraying. Using an original optical diagnostic system, we have studied melting behavior of the metal wire, break up and atomization of liquid metal. For the first time, experimental data on the in-flight velocity and temperature of spray particles in arc-plasma wire spraying were obtained. In spite of moderate particle velocities (about 50 m/s), the obtained steel coatings proved to have a low porosity of 1.5%. While studying the spraying process of tungsten wire, we observed the occurrence of anomalous high-velocity (over 4000 m/s) outbursts ejected from the surface of liquid metal droplets. The nature of such outbursts calls for further study.

  20. A versatile masking process for plasma etched backside via holes in GaAs

    NASA Astrophysics Data System (ADS)

    Howard, A. J.; Shul, R. J.; Lovejoy, M. L.; Word, J. C.

    We have developed a versatile backside via patterning process for a visible transmission modulator application. The vias are processed on mechanically thinned (approximately)100 micrometers thick GaAs using a (approximately)45 micrometers thick, negative tone, photo definable Polyimide mask and Reaction Ion Etch (RIE) plasma etching. The Polyimide masking process was found to be superior in both etch resistance and ease of use (more robust process, thicker, straighter sidewall Profile films, were more easily attained) to masking with standard optical photoresist. With the improved etch resistance (GaAs-to-polyimide etch selectivities of 10:1) we were able to Optimize Cl2-based plasma chemistries and etching conditions to achieve high GaAs etch rates in the RIE exceeding 5.0 micrometers/min. These etch optimization results along with our novel via patterning process are reported in this paper.

  1. Flow characteristic of in-flight particles in supersonic plasma spraying process

    NASA Astrophysics Data System (ADS)

    Wei, Pei; Wei, Zhengying; Zhao, Guangxi; Du, Jun; Bai, Y.

    2016-09-01

    In this paper, a computational model based on supersonic plasma spraying (SAPS) is developed to describe the plasma jet coupled with the injection of carrier gas and particles for SAPS. Based on a high-efficiency supersonic spraying gun, the 3D computational model of spraying gun was built to study the features of plasma jet and its interactions with the sprayed particles. Further the velocity and temperature of in-flight particles were measured by Spray Watch 2i, the shape of in-flight particles was observed by scanning electron microscope. Numerical results were compared with the experimental measurements and a good agreement has been achieved. The flight process of particles in plasma jet consists of three stages: accelerated stage, constant speed stage and decelerated stage. Numerical and experimental indicates that the H2 volume fraction in mixture gas of Ar + H2 should keep in the range of 23-26 %, and the distance of 100 mm is the optimal spraying distance in Supersonic atmosphere plasma spraying. Particles were melted and broken into small child particles by plasma jet and the diameters of most child particles were less than 30 μm. In general, increasing the particles impacting velocity and surface temperature can decrease the coating porosity.

  2. Dynamics of the fully stripped ion-hydrogen atom charge exchange process in dense quantum plasmas

    SciTech Connect

    Zhang, Ling-yu; Wan, Jiang-feng; Zhao, Xiao-ying; Xiao, Guo-qing; Duan, Wen-shan; Qi, Xin; Yang, Lei

    2014-09-15

    The plasma screening effects of dense quantum plasmas on charge exchange processes of a fully stripped ion colliding with a hydrogen atom are studied by the classical trajectory Monte Carlo method. The inter-particle interactions are described by the exponential cosine-screened Coulomb potentials. It is found that in weak screening conditions, cross sections increase with the increase of the ionic charge Z. However, in strong screening conditions, the dependence of cross sections on the ionic charge is related to the incident particle energy. At high energies, cross sections show a linear increase with the increase of Z, whereas at low energies, cross sections for Z≥4 become approximately the same. The He{sup 2+} and C{sup 6+} impacting charge exchange cross sections in dense quantum plasmas are also compared with those in weakly coupled plasmas. The interactions are described by the static screened Coulomb potential. It is found that for both He{sup 2+} and C{sup 6+}, the oscillatory screening effects of dense quantum plasmas are almost negligible in weak screening conditions. However, in strong screening conditions, the oscillatory screening effects enhance the screening effects of dense quantum plasmas, and the enhancement becomes more and more significant with the increase of the screening parameter and the ionic charge.

  3. The Solution Precursor Plasma Spray (SPPS) Process: A Review with Energy Considerations

    NASA Astrophysics Data System (ADS)

    Jordan, Eric H.; Jiang, Chen; Gell, Maurice

    2015-10-01

    Solution precursor plasma spray (SPPS) is a coating deposition process that uses conventional plasma spray equipment, and solution precursors, rather than ceramic or metal powders, as starting materials. Because the process is exposed to oxygen at high temperatures, nearly all coatings, to date, are oxide ceramics. In this review, both the advantages and the disadvantages of the SPPS process and some comparisons made to the suspension plasma spray (SPS) process will be discussed. The advantages of the SPPS process include rapid exploration of compositions and fabrication of advanced coatings with unique microstructural features. Examples presented span densities from porous thermal barrier coatings (TBCs) to dense TiO2 coatings. Two TBCs are in an advanced development stage: (1) a low thermal conductivity YSZ TBC and (2) a high-temperature yttrium aluminum garnet TBC. As for disadvantages, there are (1) the additional development work for each new precursor and (2) a lower standoff distance and deposition rate than the APS process, related to the evaporation of the solvent. The SPS process shares the same disadvantages. In developing new coatings, a number of factors should be considered and understood, which would help to shorten future development efforts. Future directions of the SPPS process will also be discussed.

  4. Atmospheric pressure plasma jet for bacterial decontamination and property improvement of fruit and vegetable processing wastewater

    NASA Astrophysics Data System (ADS)

    Mohamed, Abdel-Aleam H.; Shariff, Samir M. Al; Ouf, Salama A.; Benghanem, Mohamed

    2016-05-01

    An atmospheric pressure plasma jet was tested for decontaminating and improving the characteristics of wastewater derived from blackberry, date palm, tomato and beetroot processing industries. The jet was generated by blowing argon gas through a cylindrical alumina tube while a high voltage was applied between two electrodes surrounding the tube. Oxygen gas was mixed with argon at the rate of 0.2% and the argon mass flow was fixed at 4.5 slm. Images show that the generated plasma jet penetrated the treated wastewater samples. Plasma emission spectra show the presence of O and OH radicals as well as excited molecular nitrogen and argon. Complete decontamination of wastewater derived from date palm and tomato processing was achieved after 120 and 150 s exposure to the plasma jet, respectively. The bacterial count of wastewater from blackberry and beetroot was reduced by 0.41 and 2.24 log10 colony-forming units (CFU) per ml, respectively, after 180 s. Escherichia coli was the most susceptible bacterial species to the cold plasma while Shigella boydii had the minimum susceptibility, recording 1.30 and 3.34 log10 CFU ml-1, respectively, as compared to the 7.00 log10 initial count. The chemical oxygen demands of wastewater were improved by 57.5-93.3% after 180 s exposure to the plasma jet being tested. The endotoxins in the wastewater were reduced by up to 90.22%. The variation in plasma effectiveness is probably related to the antioxidant concentration of the different investigated wastewaters.

  5. Atmospheric pressure plasma jet for bacterial decontamination and property improvement of fruit and vegetable processing wastewater

    NASA Astrophysics Data System (ADS)

    Mohamed, Abdel-Aleam H.; Shariff, Samir M. Al; Ouf, Salama A.; Benghanem, Mohamed

    2016-05-01

    An atmospheric pressure plasma jet was tested for decontaminating and improving the characteristics of wastewater derived from blackberry, date palm, tomato and beetroot processing industries. The jet was generated by blowing argon gas through a cylindrical alumina tube while a high voltage was applied between two electrodes surrounding the tube. Oxygen gas was mixed with argon at the rate of 0.2% and the argon mass flow was fixed at 4.5 slm. Images show that the generated plasma jet penetrated the treated wastewater samples. Plasma emission spectra show the presence of O and OH radicals as well as excited molecular nitrogen and argon. Complete decontamination of wastewater derived from date palm and tomato processing was achieved after 120 and 150 s exposure to the plasma jet, respectively. The bacterial count of wastewater from blackberry and beetroot was reduced by 0.41 and 2.24 log10 colony-forming units (CFU) per ml, respectively, after 180 s. Escherichia coli was the most susceptible bacterial species to the cold plasma while Shigella boydii had the minimum susceptibility, recording 1.30 and 3.34 log10 CFU ml‑1, respectively, as compared to the 7.00 log10 initial count. The chemical oxygen demands of wastewater were improved by 57.5–93.3% after 180 s exposure to the plasma jet being tested. The endotoxins in the wastewater were reduced by up to 90.22%. The variation in plasma effectiveness is probably related to the antioxidant concentration of the different investigated wastewaters.

  6. PLASCON{trademark} -- A thermal plasma process for destruction of Halon 1211

    SciTech Connect

    Farmer, A.J.D.

    1998-12-31

    The international recommendations forming the Montreal Protocol essentially prohibit the manufacture and use of Ozone Depleting Substances (ODS) by signatory countries. Despite this prohibition, a significant problem remains -- what does one do with the existing ODS stockpiles? Following the Montreal recommendations, the Australian government decided to target the ODS Halon 1211, and established its Halon Bank to collect the material from industry. The stockpile of BCF in Australia is estimated to exceed 4000 tonnes and approximately 1000 tonnes of this has already been collected by the Federal Government Department of Administrative Services Centre for Environmental Management (DASCEM). Meanwhile, the Australian government research organization, CSIRO, has been collaborating with an industrial partner, Siddons Ramset Limited Plasma (SRLP), in the development of a thermal plasma reactor for BCF destruction purposes. Recently, DASCEM has established a commercial facility for BCF destruction in Australia based on the PLASCON process developed by CSIRO and SRLP. The core of the PLASCON reactor is a dc plasma torch operating with argon as the plasma gas. The presentation will include a description of the plasma reactor, a discussion of the critical scientific issues considered in the development process and some comments relating to commercialization.

  7. Microwave plasma monitoring system for the elemental composition analysis of high temperature process streams

    DOEpatents

    Woskov, Paul P.; Cohn, Daniel R.; Titus, Charles H.; Surma, Jeffrey E.

    1997-01-01

    Microwave-induced plasma for continuous, real time trace element monitoring under harsh and variable conditions. The sensor includes a source of high power microwave energy and a shorted waveguide made of a microwave conductive, high temperature capability refractory material communicating with the source of the microwave energy to generate a plasma. The high power waveguide is constructed to be robust in a hot, hostile environment. It includes an aperture for the passage of gases to be analyzed and a spectrometer is connected to receive light from the plasma. Provision is made for real time in situ calibration. The spectrometer disperses the light, which is then analyzed by a computer. The sensor is capable of making continuous, real time quantitative measurements of desired elements, such as the heavy metals lead and mercury. The invention may be incorporated into a high temperature process device and implemented in situ for example, such as with a DC graphite electrode plasma arc furnace. The invention further provides a system for the elemental analysis of process streams by removing particulate and/or droplet samples therefrom and entraining such samples in the gas flow which passes through the plasma flame. Introduction of and entraining samples in the gas flow may be facilitated by a suction pump, regulating gas flow, gravity or combinations thereof.

  8. Plasma processes in water under effect of short duration pulse discharges

    NASA Astrophysics Data System (ADS)

    Gurbanov, Elchin

    2013-09-01

    It is very important to get a clear water without any impurities and bacteria by methods, that don't change the physical and chemical indicators of water now. In this article the plasma processes during the water treatment by strong electric fields and short duration pulse discharges are considered. The crown discharge around an electrode with a small radius of curvature consists of plasma leader channels with a high conductivity, where the thermo ionization processes and UV-radiation are taken place. Simultaneously the partial discharges around potential electrode lead to formation of atomic oxygen and ozone. The spark discharge arises, when plasma leader channels cross the all interelectrode gap, where the temperature and pressure are strongly grown. As a result the shock waves and dispersing liquid streams in all discharge gap are formed. The plasma channels extend, pressure inside it becomes less than hydrostatic one and the collapse and UV-radiation processes are started. The considered physical processes can be successfully used as a basis for development of pilot-industrial installations for conditioning of drinking water and to disinfecting of sewage.

  9. The Variable Polarity Plasma Arc Welding Process: Its Application to the Space Shuttle External Tank

    NASA Technical Reports Server (NTRS)

    Nunes, A. C., Jr.; Bayless, E. O., Jr.; Wilson, W. A.

    1984-01-01

    This report describes progress in the implementation of the Variable Polarity Plasma Arc Welding (VPPAW) process at the External Tank (ET) assembly facility. Design allowable data has been developed for thicknesses up to 1.00 in. More than 24,000 in. of welding on liquid oxygen and liquid hydrogen cylinders has been made without an internal defect.

  10. No-thermal plasma processing of VOCs and NO{sub x} at LLNL

    SciTech Connect

    Merritt, B.T.; Hsiao, M.C.; Penetrante, B.M.; Vogtlin, G.E.; Wallman, P.H.

    1995-02-15

    For the past few years, Lawrence Livermore National Laboratory has been conducting a comprehensive research program on the application of non-thermal plasmas for air pollution control and abatement. This program combines an extensive modeling effort with an experimental facility and test program. We believe that there are two major issues to be addressed in order to apply non-thermal plasma processing to air pollution control; these are electrical energy consumption and byproduct identification. The thrust of our work has been to understand the scalability of the non-thermal process by focusing on the energy efficiency of the non-thermal process and to identify the byproducts to ensure that effluent gases from a non-thermal processor are benign. We have compared different types of electrical discharge reactors both theoretically and experimentally. Our interests in the application of non-thermal plasmas vary from the destruction of volatile organic compounds (VOCs) to NO{sub x} reduction for mobile applications. This paper will discuss the processing of both NO{sub x} and VOCs by non-thermal plasmas at LLNL.

  11. Non-thermal plasma treatment of Radix aconiti wastewater generated by traditional Chinese medicine processing.

    PubMed

    Wen, Yiyong; Yi, Jianping; Zhao, Shen; Jiang, Song; Chi, Yuming; Liu, Kefu

    2016-06-01

    The wastewater effluent from Radix aconiti processing, an important step in the production processes of traditional Chinese medicine (TCM), is a type of toxic wastewater and difficult to treat. Plasma oxidation methods have emerged as feasible techniques for effective decomposition of toxic organic pollutants. This study examined the performance of a plasma reactor operated in a dielectric barrier discharge (DBD) to degrade the effluent from R. aconiti processing. The effects of treatment time, discharge voltage, initial pH value and the feeding gas for the reactor on the degradation of this TCM wastewater were investigated. A bacterium bioluminescence assay was adopted in this study to test the toxicity of the TCM wastewater after non-thermal plasma treatment. The degradation ratio of the main toxic component was 87.77% after 60min treatment with oxygen used as feed gas and it was 99.59% when the initial pH value was 8.0. High discharge voltage and alkaline solution environment were beneficial for improving the degradation ratio. The treatment process was found to be capable of reducing the toxicity of the wastewater to a low level or even render it non-toxic. These experimental results suggested that the DBD plasma method may be a competitive technology for primary decomposition of biologically undegradable toxic organic pollutants in TCM wastewater.

  12. Radicals and Non-Equilibrium Processes in Low-Temperature Plasmas

    NASA Astrophysics Data System (ADS)

    Petrović, Zoran; Mason, Nigel; Hamaguchi, Satoshi; Radmilović-Radjenović, Marija

    2007-06-01

    This volume is a selection from papers presented at the 5th EU - Japan Symposium. Unfortunately not all of the authors invited to prepare a review could finalize their papers in time for publication. Thus this book displays only a part of what has been enjoyed by the audience during the conference and what was expected to be in the book. On the other hand it provides the possibility to view some of the issues in greater detail and a chance for those who attended the meeting to revisit some of the presentations and discussion. The particular value of this symposia series is the opportunity for participants to discuss the issues confronting modern plasma physics and evolve a collaborative strategy to address these issues. The resulting synergism from having the leading researchers in this field all in the same room unfortunately could not be captured in this book but will certainly be reflected in the results presented at future symposia. The 29 invited lectures and 4 progress reports (with the addition of 10 posters) presented at the conference came from 12 different countries from 4 continents. A similar distribution is maintained in the 21 articles in this book. All the papers presented here have been refereed according to the standards of the conference and the journal, first by selecting the renowned invited speakers and selecting the topics of their presentations and later on by reviewing the articles. However we still leave the responsibility (and honors) for the contents of the papers to the authors. The papers in this book are review articles giving a summary of the already published work or presenting the work in progress that will be published in full at a later date (or both). The EU - Japan Symposia were initiated in 2003 and have been held in Japan and in Europe (so far only in European countries starting with the letter `S': Sweden, Slovakia, Serbia). The 5th EU - Japan Joint Symposium on Plasma Processing was organized in Belgrade, 6-9 March at the

  13. F4TCNQ-Induced Exciton Quenching Studied by Using in-situ Photoluminescence Measurements

    NASA Astrophysics Data System (ADS)

    Zhu, Jian; Lu, Min; Wu, Bo; Hou, Xiao-Yuan

    2012-09-01

    The role of F4TCNQ as an exciton quenching material in thin organic light-emitting films is investigated by means of in situ photoluminescence measurements. C60 was used as another quenching material in the experiment for comparison, with Alq3 as a common organic light-emitting material. The effect of the growth sequence of the materials on quenching was also examined. It is found that the radius of Förster energy transfer between F4TCNQ and Alq3 is close to 0 nm and Dexter energy transfer dominates in the quenching process.

  14. Numerical methods for TVD transport and coupled relaxing processes in gases and plasmas

    NASA Technical Reports Server (NTRS)

    Cambier, Jean-Luc

    1990-01-01

    The construction of second-order upwind schemes for nonequilibrium plasmas, for both one- and two-fluid formulations is demonstrated. Coupled relaxation processes, including ionization kinetics and radiative processes and their algorithms for nonequilibrium, multiple temperature conditions are described as well. The paper applies the numerical techniques on some simple test cases, points out critical problems and their solutions, and makes qualitative comparisons with known results, whenever possible.

  15. Plasma removal of post-RIE residues for dual-damascence processing

    NASA Astrophysics Data System (ADS)

    Bliznetsov, Vladimir N.; Jo, Woo-Min

    2000-10-01

    The objective of this research was to develop a process of photoresist and polymer plasma stripping after reactive ion etching of vias and trenches in dual damascene technology. The development was implemented at Mattson low-temperature ICPsm chamber. Based on the results of designed experiment in gas mixture of O2/CF4/(N2 + 4 percent H2), the process window was established which provided clean post-strip surface with minimum dielectrics loss without using additional wet strippers.

  16. Effect of dust particle polarization on scattering processes in complex plasmas

    SciTech Connect

    Kodanova, S. K.; Ramazanov, T. S.; Bastykova, N. Kh.; Moldabekov, Zh. A.

    2015-06-15

    Screened interaction potentials in dusty plasmas taking into account the polarization of dust particles have been obtained. On the basis of screened potentials scattering processes for ion-dust particle and dust particle-dust particle pairs have been studied. In particular, the scattering cross section is considered. The scattering processes for which the dust grain polarization is unimportant have been found. The effect of zero angle dust particle-dust particle scattering is predicted.

  17. A syncopated leap-frog algorithm for orbit consistent plasma simulation of materials processing reactors

    SciTech Connect

    Cobb, J.W.; Leboeuf, J.N.

    1994-10-01

    The authors present a particle algorithm to extend simulation capabilities for plasma based materials processing reactors. The orbit integrator uses a syncopated leap-frog algorithm in cylindrical coordinates, which maintains second order accuracy, and minimizes computational complexity. Plasma source terms are accumulated orbit consistently directly in the frequency and azimuthal mode domains. Finally they discuss the numerical analysis of this algorithm. Orbit consistency greatly reduces the computational cost for a given level of precision. The computational cost is independent of the degree of time scale separation.

  18. Atomic processes and equation of state of high Z plasmas for EUV sources and their effects on the spatial and temporal evolution of the plasmas

    NASA Astrophysics Data System (ADS)

    Sasaki, Akira; Sunahara, Atushi; Furukawa, Hiroyuki; Nishihara, Katsunobu; Nishikawa, Takeshi; Koike, Fumihiro

    2016-03-01

    Laser-produced plasma (LPP) extreme ultraviolet (EUV) light sources have been intensively investigated due to potential application to next-generation semiconductor technology. Current studies focus on the atomic processes and hydrodynamics of plasmas to develop shorter wavelength sources at λ = 6.x nm as well as to improve the conversion efficiency (CE) of λ = 13.5 nm sources. This paper examines the atomic processes of mid-z elements, which are potential candidates for λ = 6.x nm source using n=3-3 transitions. Furthermore, a method to calculate the hydrodynamics of the plasmas in terms of the initial interaction between a relatively weak prepulse laser is presented.

  19. Surface roughening of ground fused silica processed by atmospheric inductively coupled plasma

    NASA Astrophysics Data System (ADS)

    Xin, Qiang; Li, Na; Wang, Jun; Wang, Bo; Li, Guo; Ding, Fei; Jin, Huiliang

    2015-06-01

    Subsurface damage (SSD) is a defect that is inevitably induced during mechanical processes, such as grinding and polishing. This defect dramatically reduces the mechanical strength and the laser damage thresholds of optical elements. Compared with traditional mechanical machining, atmospheric pressure plasma processing (APPP) is a relatively novel technology that induces almost no SSD during the processing of silica-based optical materials. In this paper, a form of APPP, inductively coupled plasma (ICP), is used to process fused silica substrates with fluorocarbon precursor under atmospheric pressure. The surface morphology evolution of ICP-processed substrates was observed and characterized by confocal laser scanning microscope (CLSM), field emission scanning electron microscope (SEM), and atomic force microscopy (AFM). The results show that the roughness evolves with the etching depth, and the roughness evolution is a single-peaked curve. This curve results from the opening and the coalescing of surface cracks and fractures. The coalescence procedure of these microstructures was simulated with two common etched pits on a polished fused silica surface. Understanding the roughness evolution of plasma-processed surface might be helpful in optimizing the optical fabrication chain that contains APPP.

  20. ICPP: Identification and Quantification of Elementary Plasma Surface Processes during thin Film Growth

    NASA Astrophysics Data System (ADS)

    Keudell, A. V.

    2000-10-01

    The quantification of elementary plasma surface processes in glow discharges used for thin film deposition, is mandatory for a complete description of these low temperature plasmas. Since the surface to volume ratio in these discharge systems is often large, all particle densities in the discharge can be strongly influenced by any surface reactions. The identification and quantification of these surface processes will be illustrated for the plasma deposition of amorphous hydrogenated carbon films. A variety of experiments will be discussed ranging from plasma experiments using the cavity technique or ionization threshold mass spectrometry as well as a new class of experiments using quantified radical beams to quantify surface reactions in terms of sticking coefficients directly. It is shown that the reactivity of the hydrocarbon radicals depends strongly on the state of hybridization of the hydrocarbon growth precursor, and that the sticking coefficients for various hydrocarbon radicals are strongly influenced by the simultaneous interaction of several reactive species with the film surface. With the knowledge of these interaction mechanisms and the quantification of the corresponding cross sections, a better understanding of growth processes has become possible, ranging from the deposition of polycrystalline diamond in microwave discharges to the formation of re-deposited layers in fusion experiments.

  1. Enhanced efficiency of laser shock cleaning process by geometrical confinement of laser-induced plasma

    SciTech Connect

    Jang, Deoksuk; Oh, Joon Ho; Kim, Dongsik; Lee, Jong-Myoung

    2009-07-01

    Surface cleaning based on the laser-induced breakdown of gas and subsequent plasma and shock wave generation can remove small particles from solid surfaces. Accordingly, several studies were performed to expand the cleaning capability of the process. In this work, the cleaning process using laser-induced plasma (LIP) under geometrical confinement is analyzed both theoretically and experimentally. Two-dimensional numerical analysis is conducted to examine the behavior of the LIP shock wave under geometrical confinement for several geometries. As a result of the analysis, we propose a simple and practical method to amplify the intensity of laser-induced shock. In the proposed method, a flat quartz plate placed close to the focal point of the laser pulse confines the expansion of the LIP, allowing the plasma to expand only in one direction. As a consequence of the plasma confinement, the intensity of the shock wave produced is increased significantly. Experiments demonstrate that the enhanced shock wave can remove smaller particles from the surface better than the existing process.

  2. Effect of Solid Shield on Coating Properties in Atmospheric Plasma Spray Process

    NASA Astrophysics Data System (ADS)

    Liu, Ting; Zheng, Lili; Zhang, Hui

    2016-08-01

    This paper investigates the impact of shrouded shield structure on plasma spray processes and the selection of optimal shield structure. Response of plasma flame characteristics to solid shield structures is studied first, and experimental investigations are then performed for both atmospheric (APS) and shrouded (SPS) plasma spray processes. It is found that the usage of conical shield (divergence angle 5.5°) with 90 mm in length is effective to form a low-oxygen (<2%) and high-temperature (>3000 K) region in the plasma flame and this region can cover the majority area for particles passing by. The average particle temperature is higher in SPS than in APS with the given conditions, and such behavior is intensified as solid shield length increases. Using the SPS process, more disk-shaped splats are obtained, and the oxygen concentration in coating is significantly reduced. The degree of the oxidation in the coatings is further reduced as the length of the solid shield increases from 50 to 90 mm. Applying solid shield will lead to high flame temperature and low oxidation; however, the substrate overheating and velocity reduction may occur. For the cases studied, the optimal shield length is around 90 mm.

  3. Acoustic emission during quench training of superconducting accelerator magnets

    NASA Astrophysics Data System (ADS)

    Marchevsky, M.; Sabbi, G.; Bajas, H.; Gourlay, S.

    2015-07-01

    Acoustic emission (AE) sensing is a viable tool for superconducting magnet diagnostics. Using in-house developed cryogenic amplified piezoelectric sensors, we conducted AE studies during quench training of the US LARP's high-field quadrupole HQ02 and the LBNL's high-field dipole HD3. For both magnets, AE bursts were observed, with spike amplitude and frequency increasing toward the quench current during current up-ramps. In the HQ02, the AE onset upon current ramping is distinct and exhibits a clear memory of the previously-reached quench current (Kaiser effect). On the other hand, in the HD3 magnet the AE amplitude begins to increase well before the previously-reached quench current (felicity effect), suggesting an ongoing progressive mechanical motion in the coils. A clear difference in the AE signature exists between the untrained and trained mechanical states in HD3. Time intervals between the AE signals detected at the opposite ends of HD3 coils were processed using a combination of narrow-band pass filtering; threshold crossing and correlation algorithms, and the spatial distributions of AE sources and the mechanical energy release were calculated. Both distributions appear to be consistent with the quench location distribution. Energy statistics of the AE spikes exhibits a power-law scaling typical for the self-organized critical state.

  4. Impact of Whole-Blood Processing Conditions on Plasma and Serum Concentrations of Cytokines.

    PubMed

    Lee, Jae-Eun; Kim, Jong-Wan; Han, Bok-Ghee; Shin, So-Youn

    2016-02-01

    Pre-analytical variations in plasma and serum samples can occur because of variability in whole-blood processing procedures. The aim of this study was to determine the impact of delayed separation of whole blood on the plasma and serum concentrations of cytokines. The concentrations of 16 cytokines were measured in plasma and serum samples when the centrifugation of whole blood at room temperature was delayed for 4, 6, 24, or 48 h, and the values were compared with those observed after separation within 2 h of whole-blood collection. Receiver operating characteristic (ROC) curve analysis was also performed for cytokines to determine whether cytokine levels in plasma and serum samples can be used to assess delayed separation of whole blood. Plasma concentrations of interleukin (IL)-1β, granulocyte-macrophage colony-stimulating factor (GM-CSF), and soluble CD40 ligand (sCD40L) and serum concentrations of IL-1β, IL-6, IL-8, macrophage inflammatory protein-1α (MIP-1α), and MIP-1β increased significantly (>2-fold) when separation was delayed at room temperature for 24 h. The concentrations of 6 of these cytokines (all except serum IL-1β and IL-6) demonstrated high diagnostic performance (area under the ROC curve >0.8) for delayed separation of whole blood. Furthermore, these cytokine concentrations typically exhibited high sensitivity and specificity at each optimal cutoff point. Conversely, IL-17A was stable in both plasma and serum samples, even when whole-blood centrifugation was delayed at room temperature for 48 h. This study shows that certain cytokines (IL-1β, GM-CSF, sCD40L, IL-8, MIP-1α, and MIP-1β) could be used for assessing the quality of plasma or serum samples. PMID:26808439

  5. Numerical and experimental investigations of MHD processes of energy transforming in inhomogenious gas-plasma flows

    SciTech Connect

    Slavin, V.S.; Gavrilov, V.M.; Lobasova, M.S.

    1995-12-31

    The results of experimental and theoretical research of MHD interaction processes of a plasma clot with carrying gas flow in Faraday MHD channel with continuous electrodes are represented. Two possible situations are being analysed: (1) working medium is air without seed, plasma clot is an equilibrium are stabilized with radiation (T-layer); (2) argon without seed, plasma exists in the form of a non-equilibrium are stabilized with electrons energy losses in elastic collisions with gas atoms. The experiment was being carried in a linear MHD channel started by a shock tube. Plasma clot was formed by an impulse electric discharge in a gasodynamic nozzle being placed between a throat and MHD channel. Self-supported current layer (T-layer) was being formed of a plasma clot under the influence of Lorentz force and Joule dissipation in the MHD channel. For compensation of near electrode voltage drop a charged battery of condensers was connected to the MHD channel electrodes instead of the load resistor. Plasma layer has steadily passed through the MHD channel {approximately}1.5 m length. In this case its parameters check well with the calculations performed on the basis of a piston model. Plasma clot initiation regime realized in this experiment was being simulated with the help of non-stationary quasi-one-dimensional design programm. Identity of the major calculation and experimental results has been shown. Dynamics of impulse strong current discharge has been studied; in so doing the role of gasodynamic expansion of a discharge zone and ionized air radiation in overall energy balance is determined.

  6. The synthesis of Pt/Ag bimetallic nanoparticles using a successive solution plasma process.

    PubMed

    Kim, Sung Min; Lee, Sang Yul; Lee, Min Hyung; Kim, Jung Wan

    2014-12-01

    A successive solution plasma process was developed for the synthesis of Pt/Ag bimetallic nanoparticles. Ag nanoparticles were made first by applying a high voltage of bipolar pulsed DC to anode and cathode electrodes composed of Ag rods. The solution containing Ag nanoparticles was discharged successively using Pt electrodes. The joule heating and electrolysis between electrodes generated vapors, and solution plasma was sustained due to progressive ionization and excitation in the vapor phase. The maximum current and voltage breakdown was observed at approximately 8.9 A and 900 V with an interval of 25 μs, which indicated that an intense solution plasma was sustained continuously. The Pt-on-Ag heterogeneous nanostructures formed, and finally, the Ag nanoparticles were completely covered by Pt nanoparticles after a discharge duration of 1,200 s. PMID:25970983

  7. Thermonuclear breakup reactions of light nuclei. I - Processes and effects. [in astrophysic plasmas

    NASA Technical Reports Server (NTRS)

    Guessoum, Nidhal; Gould, Robert J.

    1989-01-01

    Temperature and density conditions are considered for the occurrence of breakup reactions of light nuclei in astrophysical plasmas. The proton-induced endothermic process is shown to be the principal mechanism for nuclear breakdown in a plasma. The phenomenon occurs at a temperature of about 1 MeV, which is a fraction of the typical binding energy per nucleon in nuclei. The temperature for breakup of He-4 is about twice as large, because of the higher binding energy. Depending on the temperature attained in the plasma, the initial concentration of elements heavier than hydrogen can be depleted. However, if it attains a temperature of about 1 MeV, breaking up the metals (C, N, O, Ne, Mg) but not He-4, an increase in the He-4 abundance by as much as 10 percent can result, since these elements essentially break down to alpha particles.

  8. Thermal plasma processed ferro-magnetically ordered face-centered cubic iron at room temperature

    NASA Astrophysics Data System (ADS)

    Raut, Suyog A.; Kanhe, Nilesh S.; Bhoraskar, S. V.; Das, A. K.; Mathe, V. L.

    2014-10-01

    Here, we report tailor made phase of iron nanoparticles using homogeneous gas phase condensation process via thermal plasma route. It was observed that crystal lattice of nano-crystalline iron changes as a function of operating parameters of the plasma reactor. In the present investigation iron nanoparticles have been synthesized in presence of argon at operating pressures of 125-1000 Torr and fixed plasma input DC power of 6 kW. It was possible to obtain pure fcc, pure bcc as well as the mixed phases for iron nanoparticles in powder form as a function of operating pressure. The as synthesized product was characterized for understanding the structural and magnetic properties by using X-ray diffraction, vibrating sample magnetometer, and Mössbauer spectroscopy. The data reveal that fcc phase is ferromagnetically ordered with high spin state, which is unusual whereas bcc phase is found to be ferromagnetic as usual. Finally, the structural and magnetic properties are co-related.

  9. Observation of Multiple Reconnections during Self-organization Process of High Temperature Fusion Plasma

    NASA Astrophysics Data System (ADS)

    Park, H. K.; Tobias, B.; Choi, M. J.; Yun, G. S.; Domier, C. W.; Luhmann, N. C., Jr.; Munsat, T.; Donné, A. J. H.; Spakman, G. W.; Textor Team

    2011-10-01

    Images of a high resolution 2-D Electron Cyclotron Emission Imaging (ECEI) diagnostic shows evidence of multiple magnetic reconnection processes during the internal disruption of a high temperature tokamak plasmas. The disruption induces magnetic self-organization of the toroidal plasma being accompanied by successive or simultaneous multiple layer reconnection. The degree of asymmetric deformation of the internal magnetic structure (m/n=1/1 mode) prior to temperature crash influences the outcome of the disruptive behavior. The observation is critical for the building block of first principle theoretical modeling of the sawtooth oscillation in current driven toroidal plasmas and the understandings can be applied to the impulsive disruptive behavior in flares of the solar, accretion disk and stellar coronae, Earth magnetospheric storms, and controlled fusion. Work supported by the NRF of Korea, the US DOE, the NWO of the Netherlands, and the EURATOM-FOM association.

  10. Intense terahertz-pulse generation by four-wave mixing process in induced gas plasma

    NASA Astrophysics Data System (ADS)

    Wicharn, S.; Buranasiri, P.

    2015-08-01

    In this article, we have numerically investigated an intense terahertz (THz) pulses generation in gaseous plasma based on the third-order nonlinear effect, four-wave mixing rectification (FWMR). We have proposed that the fundamental fields and second-harmonic field of ultra-short pulse lasers are combined and focused into a very small gas chamber to induce a gaseous plasma, which intense THz pulse is produced. To understand the THz generation process, the first-order multiple-scale perturbation method (MSPM) has been utilized to derive a set of nonlinear coupled-mode equations for interacting fields such as two fundamental fields, a second-harmonic field, and a THz field. Then, we have simulate the intense THz-pulse generation by using split step-beam propagation method (SS-BPM) and calculated output THz intensities. Finally, the output THz intensities generated from induced air, nitrogen, and argon plasma have been compared.

  11. TiN Deposition and Process Diagnostics using Remote Plasma Sputtering

    NASA Astrophysics Data System (ADS)

    Yang, Wonkyun; Kim, Gi-Taek; Lee, Seunghun; Kim, Do-Geun; Kim, Jong-Kuk

    2013-08-01

    The discharge voltage-current characteristics and the optical diagnostics of a remote plasma sputtering system called by high density plasma assisted sputtering source (HiPASS) were investigated. The remote plasma was generated by the hollow cathode discharge (HCD) gun and was transported to the target surface by external electromagnet coils. This showed a wide process window because the sputtering voltage and current could be individually controlled. The ion density and energy distribution could be also controlled unlike the conventional magnetron sputtering. Titanium nitride films were deposited under different sputtering voltage. The high voltage mode induced the high ionization ratio of the sputtered atoms and the high ion energy toward the substrate. That resulted in the enlarged grain size, and the preferred orientation toward (220). Eventually, this optimized condition of HiPASS obtained the best hardness of TiN films to be about 48 GPa at the sputtering voltage of -800 V.

  12. Plasma Diagnostics For The Investigation of Silane Based Glow Discharge Deposition Processes

    NASA Astrophysics Data System (ADS)

    Mataras, Dimitrios

    2001-10-01

    In this work is presented the study of microcrystalline silicon PECVD process through highly diluted silane in hydrogen discharges. The investigation is performed by applying different non intrusive plasma diagnostics (electrical, optical, mass spectrometric and laser interferometric measurements). Each of these measurements is related to different plasma sub-processes (gas physics, plasma chemistry and plasma surface interaction) and compose a complete set, proper for the investigation of the effect of external discharge parameters on the deposition processes. In the specific case these plasma diagnostics are applied for prospecting the optimal experimental conditions from the ic-Si:H deposition rate point of view. Namely, the main characteristics of the effect of frequency, discharge geometry, power consumption and total gas pressure on the deposition process are presented successively. Special attention is given to the study of the frequency effect (13.56 MHz 50 MHz) indicating that the correct way to compare results of different driving frequency discharges is by maintaining constant the total power dissipation in the discharge. The important role of frequency in the achievement of high deposition rates and on the optimization of all other parameters is underlined. Finally, the proper combination of experimental conditions that result from the optimal choice of each of the above-mentioned discharge parameters and lead to high microcrystalline silicon deposition rates (7.5 Å/sec) is presented. The increase of silane dissociation rate towards neutral radicals (frequency effect), the contribution of highly sticking to the surface radicals (discharge geometry optimum) and the controlled production of higher radicals through secondary gas phase reactions (total gas pressure), are presented as prerequisites for the achievement of high deposition rates.

  13. Kinetic theory of transport processes in partially ionized reactive plasma, II: Electron transport properties

    NASA Astrophysics Data System (ADS)

    Zhdanov, V. M.; Stepanenko, A. A.

    2016-11-01

    The previously obtained in (Zhdanov and Stepanenko, 2016) general transport equations for partially ionized reactive plasma are employed for analysis of electron transport properties in molecular and atomic plasmas. We account for both elastic and inelastic interaction channels of electrons with atoms and molecules of plasma and also the processes of electron impact ionization of neutral particles and three-body ion-electron recombination. The system of scalar transport equations for electrons is discussed and the expressions for non-equilibrium corrections to electron ionization and recombination rates and the diagonal part of the electron pressure tensor are derived. Special attention is paid to analysis of electron energy relaxation during collisions with plasma particles having internal degrees of freedom and the expression for the electron coefficient of inelastic energy losses is deduced. We also derive the expressions for electron vector and tensorial transport fluxes and the corresponding transport coefficients for partially ionized reactive plasma, which represent a generalization of the well-known results obtained by Devoto (1967). The results of numerical evaluation of contribution from electron inelastic collisions with neutral particles to electron transport properties are presented for a series of molecular and atomic gases.

  14. Inactivation Process of Penicillium digitatum Spores Treated with Non-equilibrium Atmospheric Pressure Plasma

    NASA Astrophysics Data System (ADS)

    Hashizume, Hiroshi; Ohta, Takayuki; Mori, Takumi; Iseki, Sachiko; Hori, Masaru; Ito, Masafumi

    2013-05-01

    To investigate the inactivation process of Penicillium digitatum spores treated with a non-equilibrium atmospheric pressure plasma, the spores were observed using a fluorescent microscope and compared with those treated with ultraviolet (UV) light or moist heat. The treated spores were stained with two fluorescent dyes, 1,1'-dioctadecyl-3,3,Y,3'-tetramethylindocarbocyanine perchlorate (DiI) and diphenyl-1-pyrenylphosphine (DPPP). The intracellular organelles as well as cell membranes in the spores treated with the plasma were stained with DiI without a major morphological change of the membranes, while the organelles were never stained in the spores treated with UV light or moist heat. Moreover, DPPP staining revealed that organelles were oxidized by plasma treatment unlike UV light or moist heat treatments. These results suggest that only plasma treatment induces a minor structural change or functional inhibition of cell membranes, which leads to the oxidation of the intracellular organelles without a major deformation of the membranes through the penetration of reactive oxygen species generated by the plasma into the cell.

  15. Studies of dynamic processes related to active experiments in space plasmas

    NASA Technical Reports Server (NTRS)

    Banks, Peter M.; Neubert, Torsten

    1992-01-01

    This is the final report for grant NAGw-2055, 'Studies of Dynamic Processes Related to Active Experiments in Space Plasmas', covering research performed at the University of Michigan. The grant was awarded to study: (1) theoretical and data analysis of data from the CHARGE-2 rocket experiment (1keV; 1-46 mA electron beam ejections) and the Spacelab-2 shuttle experiment (1keV; 100 mA); (2) studies of the interaction of an electron beam, emitted from an ionospheric platform, with the ambient neutral atmosphere and plasma by means of a newly developed computer simulation model, relating model predictions with CHARGE-2 observations of return currents observed during electron beam emissions; and (3) development of a self-consistent model for the charge distribution on a moving conducting tether in a magnetized plasma and for the potential structure in the plasma surrounding the tether. Our main results include: (1) the computer code developed for the interaction of electrons beams with the neutral atmosphere and plasma is able to model observed return fluxes to the CHARGE-2 sounding rocket payload; and (2) a 3-D electromagnetic and relativistic particle simulation code was developed.

  16. Observation of hydrodynamic processes of radiation-ablated plasma in a small hole

    SciTech Connect

    Li, Hang; Kuang, Longyu; Jiang, Shaoen Ding, Yongkun; Song, Tianming; Yang, Jiamin Zhu, Tuo; Lin, Zhiwei; Zheng, Jianhua; Zhang, Haiying; Yu, Ruizhen; Liu, Shenye; Hu, Guangyue; Zhao, Bin; Zheng, Jian

    2015-07-15

    In the hohlraum used in laser indirect-drive inertial confinement fusion experiments, hydrodynamic processes of radiation-ablated high-Z plasma have a great effect on laser injection efficiency, radiation uniformity, and diagnosis of hohlraum radiation field from diagnostic windows (DW). To study plasma filling in the DWs, a laser-irradiated Ti disk was used to generate 2–5 keV narrow energy band X-ray as the intense backlighter source, and laser-produced X-ray in a hohlraum with low-Z foam tamper was used to heat a small hole surrounded by gold wall with 150 μm in diameter and 100 μm deep. The hydrodynamic movement of the gold plasma in the small hole was measured by an X-ray framing camera and the results are analyzed. Quantitative measurement of the plasma areal density distribution and evolution in the small hole can be used to assess the effect of plasma filling on the diagnosis from the DWs.

  17. Plasma sheet dynamics in the Jovian magnetotail: Signatures For substorm-like processes ?

    NASA Astrophysics Data System (ADS)

    Woch, J.; Krupp, N.; Khurana, K. K.; Kivelson, M. G.; Roux, A.; Perraut, S.; Louarn, P.; Lagg, A.; Williams, D. J.; Livi, S.; Wilken, B.

    During Galileo's orbit G2 in 1996 the Energetic Particles Detector (EPD) onboard the spacecraft detected a number of particle bursts with large radial/antisunward anisotropies in the distant Jovian magnetotail [Krupp et al., 1998]. In this letter we focus on a detailed analysis of one of the bursts. Prior to the onset of the burst, particle intensities at low energies increase over several hours. This phase can be interpreted as a plasma loading phase. It ends after the onset of strong distortions in the magnetic field with a bipolar excursion of the north-south component being the most prominent feature. The subsequent plasma sheet encounters show that the plasma sheet has thinned considerably. Accelerated/heated ion beams first from the Jovian direction and then later from the tail direction are seen at the plasma sheet and lobe interfaces and intense radio and plasma wave emissions are detected. The event is tentatively interpreted as a dynamical process, where the Jovian magnetotail is internally driven unstable by mass loading of magnetic flux tubes.

  18. Floating probe for electron temperature and ion density measurement applicable to processing plasmas

    SciTech Connect

    Lee, Min-Hyong; Jang, Sung-Ho; Chung, Chin-Wook

    2007-02-01

    A floating-type probe and its driving circuit using the nonlinear characteristics of the probe sheath was developed and the electron temperature and the plasma density which is found from the ion part of the probe characteristic (ion density) were measured in inductively coupled plasmas. The floating-type probe was compared with a single Langmuir probe and it turned out that the floating-type probe agrees closely with the single probe at various rf powers and pressures. The ion density and electron temperature by the floating-type probe were measured with a film on the probe tip coated in CF{sub 4} plasma. It is found that the ion density and electron temperature by the floating-type probe were almost the same regardless of the coating on the probe tip while a single Langmuir probe does not work. Because the floating-type probe is hardly affected by the deposition on the probe tip, it is expected to be applied to plasma diagnostics for plasma processing such as deposition or etching.

  19. The effect of the plasma needle on the human keratinocytes related to the wound healing process

    NASA Astrophysics Data System (ADS)

    Korolov, Ihor; Fazekas, Barbara; Széll, Márta; Kemény, Lajos; Kutasi, Kinga

    2016-01-01

    In the present study we aim to verify the influence of a non-thermal atmospheric pressure plasma on the wound healing process. In this process the major contributors are the keratinocytes, which migrate to fill in the gap created by the wound. Therefore, we performed the direct treatment of HPV-immortalized human keratinocytes, protected by a layer of phosphate buffered saline (PBS) solution, with the glow discharge generated in flowing helium by a plasma needle. To mimick a wound, a 4 mm scratch was performed on the cell culture (scratch assay). We conducted two types of experiments: (i) cell proliferation and (ii) wound-healing model experiments. The plasma needle configuration, the plasma treatment conditions and the thickness of the protecting PBS layer were set based on viability experiments. The proliferation studies showed that short, 5-10 s, and low power treatments, such as 18 W and 20 W input power, could positively influence the cell proliferation when keratinocytes were protected by PBS. On the other hand, the plasma treatment of cell medium covered keratinocytes resulted in the decrease of proliferation. The wound-healing model (scratch assay) studies showed, that there was a maximum in the wound reduction as a function of the input power and treatment time, namely, at 18 W and 5 s. Furthermore, the wound reduction strongly depended on the treated cell—PBS interaction time. To mimic an infected wound, the scratch assay was covered with a 1× {{10}9} cfu ml-1 Propionibacterium acnes suspension. The plasma treatment of this infected assay resulted in closing of the scratch, while in the non-treated assay the wound did not close at all.

  20. LAUNCHING AND QUENCHING OF BLACK HOLE RELATIVISTIC JETS AT LOW ACCRETION RATE

    SciTech Connect

    Pu, Hung-Yi; Chang, Hsiang-Kuang; Hirotani, Kouichi

    2012-10-20

    Relativistic jets are launched from black hole (BH) X-ray binaries and active galactic nuclei when the disk accretion rate is below a certain limit (i.e., when the ratio of the accretion rate to the Eddingtion accretion rate, m-dot , is below about 0.01) but quenched when above. We propose a new paradigm to explain this observed coupling between the jet and the accretion disk by investigating the extraction of the rotational energy of a BH when it is surrounded by different types of accretion disk. At low accretion rates (e.g., when m-dot {approx}<0.1), the accretion near the event horizon is quasi-spherical. The accreting plasmas fall onto the event horizon in a wide range of latitudes, breaking down the force-free approximation near the horizon. To incorporate the plasma inertia effect, we consider the magnetohydrodynamical (MHD) extraction of the rotational energy from BHs by the accreting MHD fluid, as described by the MHD Penrose process. It is found that the energy extraction operates, and hence a relativistic jet is launched, preferentially when the accretion disk consists of an outer Shakura-Sunyaev disk (SSD) and an inner advection-dominated accretion flow. When the entire accretion disk type changes into an SSD, the jet is quenched because the plasmas bring more rest-mass energy than what is extracted from the hole electromagnetically to stop the extraction. Several other issues related to observed BH disk-jet couplings, such as why the radio luminosity increases with increasing X-ray luminosity until the radio emission drops, are also explained.

  1. Microstructural analysis of martensite constituents in quenching and partitioning steels

    SciTech Connect

    Santofimia, M.J.; Petrov, R.H.; Zhao, L.; Sietsma, J.

    2014-06-01

    A methodology to distinguish martensite formed in the first quench (M1) from martensite formed in the second quench (M2) of the Quenching and Partitioning process is presented, enabling the study of the structural characteristics of both microstructural constituents. Investigations show that M1 displays larger block size and less lattice imperfections than M2, differences that can be related to their respective carbon contents. - Highlights: • An approach to distinguish “old” from “new” martensite in Q and P steels is presented • Methodology allows separate characterization of microstructure and crystallography “Old” martensite has larger block size and more perfect lattice than the “new” one • The differences between the old and new martensite depend on their carbon contents.

  2. A stop-restart solid propellant study with salt quench

    NASA Technical Reports Server (NTRS)

    Kumar, R. N.

    1976-01-01

    Experiments were conducted to gain insight into the unsatisfactory performance of the salt quench system of solid propellants in earlier studies. Nine open-air salt spray tests were conducted and high-speed cinematographic coverage was obtained of the events. It is shown that the salt spray by the detonator is generally a two-step process yielding two different fractions. The first fraction consists of finely powdered salt and moves practically unidirectionally at a high velocity (thousand of feet per second) while the second fraction consists of coarse particles and moves randomly at a low velocity (a few feet per second). Further investigation is required to verify the speculation that a lower quench charge ratio (weight of salt/propellant burning area) than previously employed may lead to an efficient quench

  3. Sensitive iodate sensor based on fluorescence quenching of gold nanocluster.

    PubMed

    Li, Ruiping; Xu, Pingping; Fan, Jun; Di, Junwei; Tu, Yifeng; Yan, Jilin

    2014-05-27

    In this report we described a highly selective and sensitive iodate sensor. Due to its interaction with fluorescent gold nanoclusters, iodate was capable of oxidizing and etching gold core of the nanoclusters, resulting in fluorescence quenching. Furthermore, it was found that extra iodide ion could enhance this etching process, and even a small amount of iodate could lead to significant quenching. Under an optimized condition, linear relationship between the iodate concentration and the fluorescence quenching was obtained in the range 10 nM-1 μM. The developed iodate sensor was found selective and capable of detecting iodate as low as 2.8 nM. The sensor was then applied for the analysis of iodate in real sample and satisfactory recoveries were obtained.

  4. Quench Module Insert Capabilities and Development Test Results

    NASA Technical Reports Server (NTRS)

    Carswell, William E.; Crouch, M. R.; Farmer, J.; Breeding, S.; Rose, F.; Whitaker, Ann F. (Technical Monitor)

    2001-01-01

    The Quench Module Insert is a directional solidification furnace that will operate in the Materials Science Research Rack (MSRR) on the International Space Station. It will provide high thermal gradient and quench capabilities for processing metals and alloys in microgravity. Numerical analyses and breadboard testing conducted to date show that the QMI can produce an axial temperature gradient approaching 150 C per centimeter in a 1 centimeter diameter aluminum sample with a maximum molten sample temperature of 1100 C. Breadboard testing and analysis have also shown that the quench capabilities of the furnace are sufficient to rapidly solidify at least a 5mm axial portion of a 1 centimeter diameter molten aluminum sample in significantly less than the required 2 seconds and prevent significant backmelt. This paper presents the furnace requirements and capabilities and a status of the associated development testing and analyses.

  5. Ergodic and nonergodic processes coexist in the plasma membrane as observed by single-molecule tracking

    PubMed Central

    Weigel, Aubrey V.; Simon, Blair; Tamkun, Michael M.; Krapf, Diego

    2011-01-01

    Diffusion in the plasma membrane of living cells is often found to display anomalous dynamics. However, the mechanism underlying this diffusion pattern remains highly controversial. Here, we study the physical mechanism underlying Kv2.1 potassium channel anomalous dynamics using single-molecule tracking. Our analysis includes both time series of individual trajectories and ensemble averages. We show that an ergodic and a nonergodic process coexist in the plasma membrane. The ergodic process resembles a fractal structure with its origin in macromolecular crowding in the cell membrane. The nonergodic process is found to be regulated by transient binding to the actin cytoskeleton and can be accurately modeled by a continuous-time random walk. When the cell is treated with drugs that inhibit actin polymerization, the diffusion pattern of Kv2.1 channels recovers ergodicity. However, the fractal structure that induces anomalous diffusion remains unaltered. These results have direct implications on the regulation of membrane receptor trafficking and signaling. PMID:21464280

  6. Design and fabrication of a glovebox for the Plasma Hearth Process radioactive bench-scale system

    SciTech Connect

    Wahlquist, D.R.

    1996-07-01

    This paper presents some of the design considerations and fabrication techniques for building a glovebox for the Plasma Hearth Process (PHP) radioactive bench-scale system. The PHP radioactive bench-scale system uses a plasma torch to process a variety of radioactive materials into a final vitrified waste form. The processed waste will contain plutonium and trace amounts of other radioactive materials. The glovebox used in this system is located directly below the plasma chamber and is called the Hearth Handling Enclosure (HHE). The HHE is designed to maintain a confinement boundary between the processed waste and the operator. Operations that take place inside the HHE include raising and lowering the hearth using a hydraulic lift table, transporting the hearth within the HHE using an overhead monorail and hoist system, sampling and disassembly of the processed waste and hearth, weighing the hearth, rebuilding a hearth, and sampling HEPA filters. The PHP radioactive bench-scale system is located at the TREAT facility at Argonne National Laboratory-West in Idaho Falls, Idaho.

  7. Thermal Barrier Coatings Made by the Solution Precursor Plasma Spray Process

    NASA Astrophysics Data System (ADS)

    Gell, Maurice; Jordan, Eric H.; Teicholz, Matthew; Cetegen, Baki M.; Padture, Nitin P.; Xie, Liangde; Chen, Dianying; Ma, Xinqing; Roth, Jeffrey

    2008-03-01

    The solution precursor plasma spray (SPPS) process is a relatively new and flexible thermal spray process that can produce a wide variety of novel materials, including some with superior properties. The SPPS process involves injecting atomized droplets of a precursor solution into the plasma. The properties of resultant deposits depend on the time-temperature history of the droplets in the plasma, ranging from ultra-fine splats to unmelted crystalline particles to unpyrolized particles. By controlling the volume fraction of these three different constituents, a variety of coatings can be produced, all with a nanograin size. In this article, we will be reviewing research related to thermal barrier coatings, emphasizing the processing conditions necessary to obtain a range of microstructures and associated properties. The SPPS process produces a unique strain-tolerant, low-thermal conductivity microstructure consisting of (i) three-dimensional micrometer and nanometer pores, (ii) through-coating thickness (vertical) cracks, (iii) ultra-fine splats, and (iv) inter-pass boundaries. Both thin (0.12 mm) and thick (4 mm) coatings have been fabricated. The volume fraction of porosity can be varied from 10% to 40% while retaining the characteristic microstructure of vertical cracks and ultra-fine splats. The mechanism of vertical crack formation will be described.

  8. Jet quenching at RHIC. What have we learned?

    SciTech Connect

    Ploskon, Mateusz

    2009-12-17

    Partonic energy loss (jet quenching) within the hot and colored medium created in heavy-ion collisions is one of the essential tools to provide quantitative understanding of Quark Gluon Plasma. Measurements of jet quenching via single and di-hadron observables have provided initial estimates of the energy density of the medium. However, these hadron-triggered observables suffer from well-known biases since they fold production cross-sections with the energy loss itself, providing limited information on the initial energy of the propagating jet. Fully reconstructed jets - in terms of energy flow - will allow a complete exploration of fragmentation patterns and will not suffer from geometrical biases, providing deeper understanding of partonic energy loss. We recall the pioneering hadron triggered measurements, summarize their impact and put them in contrast to the recent measurements of fully reconstructed jets in heavy-ions at RHIC.

  9. The reactions of carbon in a hydrogen plasma

    SciTech Connect

    Li, M.; Fan, Y.; Bao, W.; Guan, Y.; Li, S.

    2006-07-01

    Acetylene can be directly produced by coal pyrolysis in hydrogen plasma. A key factor affecting acetylene yield is whether the residue solid carbon is able to react with hydrogen to form acetylene after volatile matters released from coal powders pyrolyzed in hydrogen plasma. Reactions of carbon in hydrogen plasma are studied in this article. The study showed that solid carbon could hardly react with hydrogen at temperatures below the sublimation point, while sublimated carbon could easily react with hydrogen at temperatures above sublimation point, and mainly acetylene and other hydrocarbons can be obtained after quenching process.

  10. Quantitative Imaging in Laboratory: Fast Kinetics and Fluorescence Quenching

    ERIC Educational Resources Information Center

    Cumberbatch, Tanya; Hanley, Quentin S.

    2007-01-01

    The process of quantitative imaging, which is very commonly used in laboratory, is shown to be very useful for studying the fast kinetics and fluorescence quenching of many experiments. The imaging technique is extremely cheap and hence can be used in many absorption and luminescence experiments.

  11. Energy and costs scoping study for plasma pyrolysis thermal processing system

    SciTech Connect

    Sherick, K.E.; Findley, J.E.

    1992-01-01

    The purpose of this study was to provide information in support of an investigation of thermal technologies as possible treatment process for buried wastes at the INEL. Material and energy balances and a cost estimate were generated for a representative plasma torch-based thermal waste treatment system operating in a pyrolysis mode. Two waste streams were selected which are representative of INEL buried wastes, large in volume, and difficult to treat by other technologies. These streams were a solidified nitrate sludge waste stream and a waste/soil mix of other buried waste components. The treatment scheme selected includes a main plasma chamber operating under pyrolyzing conditions; a plasma afterburner to provide additional residence time at high temperature to ensure complete destruction of hazardous organics; an off-gas treatment system; and a incinerator and stack to oxidize carbon monoxide to carbon dioxide and vent the clean, oxidized gases to atmosphere. The material balances generated provide materials flow and equipment duty information of sufficient accuracy to generate initial rough-order-of-magnitude (ROM) system capital and operating cost estimates for a representative plasma thermal processing system.

  12. Electron capture and excitation processes in H+‑H collisions in dense quantum plasmas

    NASA Astrophysics Data System (ADS)

    Jakimovski, D.; Markovska, N.; Janev, R. K.

    2016-10-01

    Electron capture and excitation processes in proton–hydrogen atom collisions taking place in dense quantum plasmas are studied by employing the two-centre atomic orbital close-coupling (TC-AOCC) method. The Debye–Hückel cosine (DHC) potential is used to describe the plasma screening effects on the Coulomb interaction between charged particles. The properties of a hydrogen atom with DHC potential are investigated as a function of the screening strength of the potential. It is found that the decrease in binding energy of nl levels with increasing screening strength is considerably faster than in the case of the Debye–Hückel (DH) screening potential, appropriate for description of charged particle interactions in weakly coupled classical plasmas. This results in a reduction in the number of bound states in the DHC potential with respect to that in the DH potential for the same plasma screening strength, and is reflected in the dynamics of excitation and electron capture processes for the two screened potentials. The TC-AOCC cross sections for total and state-selective electron capture and excitation cross sections with the DHC potential are calculated for a number of representative screening strengths in the 1–300 keV energy range and compared with those for the DH and pure Coulomb potential. The total capture cross sections for a selected number of screening strengths are compared with the available results from classical trajectory Monte Carlo calculations.

  13. Process for producing plasma sprayed carbide-based coatings with minimal decarburization and near theoretical density

    SciTech Connect

    Lenling, W.J. ); Smith, M.F.; Henfling, J.A. )

    1990-01-01

    Plasma spray deposition of carbide/metal hardcoatings is difficult because complex chemical transformations can occur while spraying, especially in the presence of oxygen. A commercial plasma spray torch has been modified to simultaneously inject carbide powder and a metal alloy powder at two different locations in the plasma stream. Composite hardcoatings of tungsten carbide/cobalt with a nickel-base alloy matrix have been produce with this dual-injection spray process and compared to coatings sprayed with a conventional plasma spray process. X-ray diffraction revealed very little change in the carbide phase composition of dual-injection coatings as compared to the original composition of the carbide spray powder. Conversely, the conventionally sprayed coatings showed significant transformation of the WC phase to the less desirable W{sub 2}C phase, and secondary oxy- carbide phases were also clearly evident. Porosity in the dual- injection coatings was consistently less than 2%, as measured by image analysis of polished metallographic samples. Microhardness results for the dual injection coatings also compared very favorably with values for the conventional coatings. Preliminary results from an ongoing abrasive wear study indicate that the dual-injection coatings are more wear resistant than the conventional coatings, but further research is needed. 6 refs., 3 figs., 3 tabs.

  14. Simulation of the O-X-B conversion process in dense magnetized plasmas

    NASA Astrophysics Data System (ADS)

    Asgarian, Mohammad Ali; Verboncoeur, John; Parvazian, Akbar

    2012-10-01

    Electron Bernstein waves (EBWs) are special electrostatic cyclotron waves which propagate with a short wavelength in hot plasma. EBWs are useful for core plasma heating, current drive and temperature diagnostics in high density plasma devices like stellarators and tokamaks. The resonance of EBWs is close to the cyclotron harmonics, and they do not have a density cut-off. The ordinary-extraordinary-Bernstein(O-X-B) conversion is one of the processes for generating EBWs. The generated EBW propagates in the region with density higher than ordinary wave cut-off and is strongly absorbed at the electron cyclotron harmonics. As such, EBWs may provide local electron heating and current drive. This double conversion process has been simulated using the XOOPIC code. XOOPIC is a 2D PIC code with 3D electrostatic and electromagnetic field solvers for slab and cylindrical geometries. The O-X-B simulation has been done in a slab plasma, using the electromagnetic field solver and a surface impedance wave source to generate the O-wave. The maximum energy transformation in O-X conversion will be ensured with the optimized refractive index, parallel to toroidal magnetic field. Moreover, the dependence of the conversion efficiency on the density gradient scale length will be considered.

  15. A SIMPLE METHOD FOR MODELING COLLISION PROCESSES IN PLASMAS WITH A KAPPA ENERGY DISTRIBUTION

    SciTech Connect

    Hahn, M.; Savin, D. W.

    2015-08-20

    We demonstrate that a nonthermal distribution of particles described by a kappa distribution can be accurately approximated by a weighted sum of Maxwell–Boltzmann distributions. We apply this method to modeling collision processes in kappa-distribution plasmas, with a particular focus on atomic processes important for solar physics. The relevant collision process rate coefficients are generated by summing appropriately weighted Maxwellian rate coefficients. This method reproduces the rate coefficients for a kappa distribution to an estimated accuracy of better than 3%. This is equal to or better than the accuracy of rate coefficients generated using “reverse-engineering” methods, which attempt to extract the needed cross sections from the published Maxwellian rate coefficient data and then reconvolve the extracted cross sections with the desired kappa distribution. Our approach of summing Maxwellian rate coefficients is easy to implement using existing spectral analysis software. Moreover, the weights in the sum of the Maxwell–Boltzmann distribution rate coefficients can be found for any value of the parameter κ, thereby enabling one to model plasmas with a time-varying κ. Tabulated Maxwellian fitting parameters are given for specific values of κ from 1.7 to 100. We also provide polynomial fits to these parameters over this entire range. Several applications of our technique are presented, including the plasma equilibrium charge state distribution (CSD), predicting line ratios, modeling the influence of electron impact multiple ionization on the equilibrium CSD of kappa-distribution plasmas, and calculating the time-varying CSD of plasmas during a solar flare.

  16. Direct Simulation Monte Carlo Simulations of Low Pressure Semiconductor Plasma Processing

    SciTech Connect

    Gochberg, L. A.; Ozawa, T.; Deng, H.; Levin, D. A.

    2008-12-31

    The two widely used plasma deposition tools for semiconductor processing are Ionized Metal Physical Vapor Deposition (IMPVD) of metals using either planar or hollow cathode magnetrons (HCM), and inductively-coupled plasma (ICP) deposition of dielectrics in High Density Plasma Chemical Vapor Deposition (HDP-CVD) reactors. In these systems, the injected neutral gas flows are generally in the transonic to supersonic flow regime. The Hybrid Plasma Equipment Model (HPEM) has been developed and is strategically and beneficially applied to the design of these tools and their processes. For the most part, the model uses continuum-based techniques, and thus, as pressures decrease below 10 mTorr, the continuum approaches in the model become questionable. Modifications have been previously made to the HPEM to significantly improve its accuracy in this pressure regime. In particular, the Ion Monte Carlo Simulation (IMCS) was added, wherein a Monte Carlo simulation is used to obtain ion and neutral velocity distributions in much the same way as in direct simulation Monte Carlo (DSMC). As a further refinement, this work presents the first steps towards the adaptation of full DSMC calculations to replace part of the flow module within the HPEM. Six species (Ar, Cu, Ar*, Cu*, Ar{sup +}, and Cu{sup +}) are modeled in DSMC. To couple SMILE as a module to the HPEM, source functions for species, momentum and energy from plasma sources will be provided by the HPEM. The DSMC module will then compute a quasi-converged flow field that will provide neutral and ion species densities, momenta and temperatures. In this work, the HPEM results for a hollow cathode magnetron (HCM) IMPVD process using the Boltzmann distribution are compared with DSMC results using portions of those HPEM computations as an initial condition.

  17. Holographic quenches and anomalous transport

    NASA Astrophysics Data System (ADS)

    Ammon, Martin; Grieninger, Sebastian; Jimenez-Alba, Amadeo; Macedo, Rodrigo P.; Melgar, Luis

    2016-09-01

    We study the response of the chiral magnetic effect due to continuous quenches induced by time dependent electric fields within holography. Concretely, we consider a holographic model with dual chiral anomaly and compute the electric current parallel to a constant, homogeneous magnetic field and a time dependent electric field in the probe approximation. We explicitly solve the PDEs by means of pseudospectral methods in spatial and time directions and study the transition to an universal "fast" quench response. Moreover, we compute the amplitudes, i.e., residues of the quasi normal modes, by solving the (ODE) Laplace transformed equations. We investigate the possibility of considering the asymptotic growth rate of the amplitudes as a well defined notion of initial time scale for linearized systems. Finally, we highlight the existence of Landau level resonances in the electrical conductivity parallel to a magnetic field at finite frequency and show explicitly that these only appear in presence of the anomaly. We show that the existence of these resonances induces, among others, a long-lived AC electric current once the electric field is switched off.

  18. Modeling the formation of the quench product in municipal solid waste incineration (MSWI) bottom ash.

    PubMed

    Inkaew, Kanawut; Saffarzadeh, Amirhomayoun; Shimaoka, Takayuki

    2016-06-01

    This study investigated changes in bottom ash morphology and mineralogy under lab-scale quenching conditions. The main purpose was to clarify the mechanisms behind the formation of the quench product/layer around bottom ash particles. In the experiments, the unquenched bottom ashes were heated to 300°C for 1h, and were quenched by warm water (65°C) with different simulated conditions. After having filtered and dried, the ashes were analyzed by a combination of methodologies namely, particle size distribution analysis, intact particle and thin-section observation, X-ray diffractometry, and scanning electron microscope with energy dispersive X-ray spectroscopy. The results indicated that after quenching, the morphology and mineralogy of the bottom ash changed significantly. The freshly quenched bottom ash was dominated by a quench product that was characterized by amorphous and microcrystalline calcium-silicate-hydrate (CSH) phases. This product also enclosed tiny minerals, glasses, ceramics, metals, and organic materials. The dominant mineral phases produced by quenching process and detected by XRD were calcite, Friedel's salt, hydrocalumite and portlandite. The formation of quench product was controlled by the fine fraction of the bottom ash (particle size <0.425mm). From the observations, a conceptual model of the ash-water reactions and formation of the quench product in the bottom ash was proposed. PMID:27079853

  19. Rapid Quench in an Electrostatic Levitator

    NASA Technical Reports Server (NTRS)

    SanSoucie, Michael P.; Rogers, Jan R.; Matson, Michael M.

    2016-01-01

    The Electrostatic Levitation (ESL) Laboratory at the NASA Marshall Space Flight Center (MSFC) is a unique facility for investigators studying high-temperature materials. The ESL laboratory’s main chamber has been upgraded with the addition of a rapid quench system. This system allows samples to be dropped into a quench vessel that can be filled with a low melting point material, such as a gallium or indium alloy, as a quench medium. Thereby allowing rapid quenching of undercooled liquid metals. Up to eight quench vessels can be loaded into a wheel inside the chamber that is indexed with control software. The system has been tested successfully with samples of zirconium, iron-cobalt alloys, iron-chromium-nickel, titanium-zirconium-nickel alloys, and a silicon-cobalt alloy. This new rapid quench system will allow materials science studies of undercooled materials and new materials development. The system is described and some initial results are presented.

  20. Rapid Quench in an Electrostatic Levitator

    NASA Technical Reports Server (NTRS)

    SanSoucie, Michael P.; Rogers, Jan R.; Matson, Douglas M.

    2016-01-01

    The Electrostatic Levitation (ESL) Laboratory at the NASA Marshall Space Flight Center (MSFC) is a unique facility for investigators studying high-temperature materials. The ESL laboratory's main chamber has been upgraded with the addition of a rapid quench system. This system allows samples to be dropped into a quench vessel that can be filled with a low melting point material, such as a gallium or indium alloy, as a quench medium. Thereby allowing rapid quenching of undercooled liquid metals. Up to eight quench vessels can be loaded into a wheel inside the chamber that is indexed with control software. The system has been tested successfully with samples of zirconium, iron-cobalt alloys, titanium-zirconium-nickel alloys, and a silicon-cobalt alloy. This new rapid quench system will allow materials science studies of undercooled materials and new materials development. In this presentation, the system is described and some initial results are presented.

  1. Measurement and Processing of Fast Pulsed Discharge Current in Plasma Focus Machines

    NASA Astrophysics Data System (ADS)

    Lee, S.; Saw, S. H.; Rawat, R. S.; Lee, P.; Verma, R.; Talebitaher, A.; Hassan, S. M.; Abdou, A. E.; Ismail, Mohamed; Mohamed, Amgad; Torreblanca, H.; Al Hawat, Sh.; Akel, M.; Chong, P. L.; Roy, F.; Singh, A.; Wong, D.; Devi, K.

    2012-04-01

    The fast pulsed electric discharge current drives all physical processes in the plasma focus device; in turn all physical processes in the focus affect the current waveform. Thus the discharge current waveform is the most important indicator of plasma focus performance. This underlies the importance of properly measuring, processing and interpreting the discharge current waveform. This paper reports the measurement of fast pulsed discharge current by the Rogowski coil, in two different modes: the current transformer, "I" mode, and current derivative, "Idot" mode. The processing and interpretation of recorded current waveform to obtain useful information about the physical processes in the plasma focus device are discussed. The current transformer with a large number of turns and a sub-1 Ohm terminator has good high frequency response, necessary for the sharp current dip region when dI/ dt exceeds 2 × 1011 A/s. However the signal is "noisy" in the current dip region. Several methods to extract the current dip from the noise are discussed and examples of how low pass filters affect the signals are shown. The dI/ dt coil, the Rogowski coil in "Idot" mode, with a few turns terminated by 50-Ohm is also described. Integrating the 1 GSa/s digital waveform does remove the high frequency noise components, yet the extracted waveform shows sharp angular features indicative of the retention of short-time features. This makes the dI/ dt coil superior to the current transformer. A 7-turn coil is tested against the Lee Model code and found to be suitable to measure the plasma focus discharge current.

  2. Process, properties, and environmental response of plasma sprayed thermal barrier coatings

    NASA Technical Reports Server (NTRS)

    Novak, Richard C.

    1995-01-01

    Experimental results are shown which demonstrate that the properties of plasma sprayed fully stabilized zirconia are strongly influenced by the process parameters. Properties of the coatings in the as-sprayed condition are shown to be additionally influenced by environmental exposure. This behavior is dependent on raw material considerations and processing conditions as well as exposure time and temperature. Process control methodology is described which can take into consideration these complex interactions and help to produce thermal barrier coatings in a cost effective way while meeting coating technical requirements.

  3. Process, properties and environmental response of plasma sprayed thermal barrier coatings

    NASA Technical Reports Server (NTRS)

    Novak, R. C.

    1995-01-01

    Experimental results are shown which demonstrate that the properties of plasma sprayed fully stabilized zirconia are strongly influenced by the process parameters. Properties of the coatings in the as-sprayed condition are shown to be additionally influenced by environmental exposure. This behavior is dependent on raw material considerations and processing conditions as well as exposure time and temperature. Process control methodology is described which can take into consideration these complex interactions and help to produce thermal barrier coatings in a cost effective way while meeting coating technical requirements.

  4. Plasma vitrification of waste materials

    DOEpatents

    McLaughlin, David F.; Dighe, Shyam V.; Gass, William R.

    1997-01-01

    This invention provides a process wherein hazardous or radioactive wastes in the form of liquids, slurries, or finely divided solids are mixed with finely divided glassformers (silica, alumina, soda, etc.) and injected directly into the plume of a non-transferred arc plasma torch. The extremely high temperatures and heat transfer rates makes it possible to convert the waste-glassformer mixture into a fully vitrified molten glass product in a matter of milliseconds. The molten product may then be collected in a crucible for casting into final wasteform geometry, quenching in water, or further holding time to improve homogeneity and eliminate bubbles.

  5. Plasma vitrification of waste materials

    DOEpatents

    McLaughlin, D.F.; Dighe, S.V.; Gass, W.R.

    1997-06-10

    This invention provides a process wherein hazardous or radioactive wastes in the form of liquids, slurries, or finely divided solids are mixed with finely divided glassformers (silica, alumina, soda, etc.) and injected directly into the plume of a non-transferred arc plasma torch. The extremely high temperatures and heat transfer rates makes it possible to convert the waste-glassformer mixture into a fully vitrified molten glass product in a matter of milliseconds. The molten product may then be collected in a crucible for casting into final wasteform geometry, quenching in water, or further holding time to improve homogeneity and eliminate bubbles. 4 figs.

  6. Expert system and process optimization techniques for real-time monitoring and control of plasma processes

    NASA Astrophysics Data System (ADS)

    Cheng, Jie; Qian, Zhaogang; Irani, Keki B.; Etemad, Hossein; Elta, Michael E.

    1991-03-01

    To meet the ever-increasing demand of the rapidly-growing semiconductor manufacturing industry it is critical to have a comprehensive methodology integrating techniques for process optimization real-time monitoring and adaptive process control. To this end we have accomplished an integrated knowledge-based approach combining latest expert system technology machine learning method and traditional statistical process control (SPC) techniques. This knowledge-based approach is advantageous in that it makes it possible for the task of process optimization and adaptive control to be performed consistently and predictably. Furthermore this approach can be used to construct high-level and qualitative description of processes and thus make the process behavior easy to monitor predict and control. Two software packages RIST (Rule Induction and Statistical Testing) and KARSM (Knowledge Acquisition from Response Surface Methodology) have been developed and incorporated with two commercially available packages G2 (real-time expert system) and ULTRAMAX (a tool for sequential process optimization).

  7. Polymer quenched prealloyed metal powder

    DOEpatents

    Hajaligol, Mohammad R.; Fleischhauer, Grier; German, Randall M.

    2001-01-01

    A powder metallurgical process of preparing a sheet from a powder having an intermetallic alloy composition such as an iron, nickel or titanium aluminide. The sheet can be manufactured into electrical resistance heating elements having improved room temperature ductility, electrical resistivity, cyclic fatigue resistance, high temperature oxidation resistance, low and high temperature strength, and/or resistance to high temperature sagging. The iron aluminide has an entirely ferritic microstructure which is free of austenite and can include, in weight %, 4 to 32% Al, and optional additions such as .ltoreq.1% Cr, .gtoreq.0.05% Zr .ltoreq.2% Ti, .ltoreq.2% Mo, .ltoreq.1% Ni, .ltoreq.0.75% C, .ltoreq.0.1% B, .ltoreq.1% submicron oxide particles and/or electrically insulating or electrically conductive covalent ceramic particles, .ltoreq.1% rare earth metal, and/or .ltoreq.3 % Cu. The process includes forming a non-densified metal sheet by consolidating a powder having an intermetallic alloy composition such as by roll compaction, tape casting or plasma spraying, forming a cold rolled sheet by cold rolling the non-densified metal sheet so as to increase the density and reduce the thickness thereof and annealing the cold rolled sheet. The powder can be a water, polymer or gas atomized powder which is subjecting to sieving and/or blending with a binder prior to the consolidation step. After the consolidation step, the sheet can be partially sintered. The cold rolling and/or annealing steps can be repeated to achieve the desired sheet thickness and properties. The annealing can be carried out in a vacuum furnace with a vacuum or inert atmosphere. During final annealing, the cold rolled sheet recrystallizes to an average grain size of about 10 to 30 .mu.m. Final stress relief annealing can be carried out in the B2 phase temperature range.

  8. Plasma hearth process vitrification of DOE low-level mixed waste

    SciTech Connect

    Gillins, R.L.; Geimer, R.M.

    1995-11-01

    The Plasma Hearth Process (PHP) demonstration project is one of the key technology projects in the Department of Energy (DOE) Office of Technology Development Mixed Waste Focus Area. The PHP is recognized as one of the more promising solutions to DOE`s mixed waste treatment needs, with potential application in the treatment of a wide variety of DOE mixed wastes. The PHP is a high temperature vitrification process using a plasma arc torch in a stationary, refractory lined chamber that destroys organics and stabilizes the residuals in a nonleaching, vitrified waste form. This technology will be equally applicable to low-level mixed wastes generated by nuclear utilities. The final waste form will be volume reduced to the maximum extent practical, because all organics will have been destroyed and the inorganics will be in a high-density, low void-space form and little or no volume-increasing glass makers will have been added.

  9. Thermal quenching of fluorescence in condensed media

    NASA Astrophysics Data System (ADS)

    Lagos, Miguel; Paredes, Rodrigo

    2016-09-01

    Environmental factors strongly affect the features of the electromagnetic spectra of fluorescent compounds hosted by material media. The shape of the absorption and emission peaks, their characteristic asymmetry and breadth, the Stokes shift and quantum yield are generally temperature dependent and heavily influenced by both the local and extended physical properties of the medium. The theoretical method used before to obtain the lineshape function is extended here to other terms of the interaction energy between the optically sensitive orbital and the hosting medium, which become significant when the spectral feature is broad. An analytical expression for the temperature dependent decay rate by non-radiative processes is obtained by this way. Comparison with experiment on thermal quenching gives agreement within the experimental uncertainty. The solvent polarity, its protic or aprotic character, hydrogen bonds, proximity effects and presence of quenchers are expected to enter through the coupling constants of the corresponding energy terms.

  10. Ion drag force on an absorbing grain in highly collisional plasma in the presence of plasma production and loss processes

    SciTech Connect

    Chaudhuri, Manis; Khrapak, Sergei A.; Morfill, Gregor E.

    2008-09-07

    The ion drag force acting on a small absorbing spherical grain has been calculated analytically in highly collisional plasma with slowly drifting ions taking into account plasma production and loss mechanisms in the vicinity of the grain. It is shown that both the magnitude and direction of the ion drag force are strongly influenced by the plasma production and loss mechanisms. The parameter regimes for the 'positive' and 'negative' ion drag forces acting on an absorbing grain have been identified.

  11. Auroral plasma transport processes in the presence of kV potential structures

    NASA Technical Reports Server (NTRS)

    Ganguli, Supriya B.; Mitchell, H. G.; Palmadesso, P. J.

    1994-01-01

    We have simulated plasma transport processes in the presence of a quasi-two-dimensional current filament, that generated kV potential structure in the auroral region. The simulation consists of a set of one-dimensional flux tube simulations with different imposed time-dependent, field-aligned currents. The model uses the 16 moment system of equations and simultaneously solves coupled continuity and momentum equations and equations describing the transport along the magnetic field lines of parallel and perpendicular thermal energy and heat flows for each species. The lower end of the simulation is at an altitude of 800 km, in the collisional topside ionosphere, while the upper end is at 10 R(sub E) in the magnetosphere. The plasma consists of hot electrons and protons of magnetospheric origin and low-energy electrons, protons, and oxygen ions of ionospheric origin. The dynamical interaction of the individual current filaments with ionospheric and magnetospheric plasma generates a potential structure in the horizontal direction and kilovolt field-aligned potential drops along the field lines. The side-by-side display exhibits the evolution of the implied potential structure in the horizontial direction. In the presence of this potential structure and parallel electric field ionospheric plasma density is depleted and velocity is reduced, while density enhancement and increased velocity is observed in magnetospheric plasma. The ionospheric and magnetospheric electron temperatures increase below 2 R(sub E) due to magnetic mirror force on converging geomagnetic field lines. The primary cross-field motion produced by the horizontal E field (E x B drift) is perpendicular to both of the significant spatial directions and is thus ignorable in this geometry. The effects of other cross-field drift processes are discussed. The simulation thus provides insight into the dynamical evolution of two-dimensional potential structures driven by an imposed finite width, field

  12. Development of a scanning nanopipette probe microscope for fine processing using atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Morimatsu, Daisuke; Sugimoto, Hiromitsu; Nakamura, Atsushi; Ogino, Akihisa; Nagatsu, Masaaki; Iwata, Futoshi

    2016-08-01

    We developed a novel technique for fine material processing based on a localized atmospheric-pressure plasma jet (APPJ) using a scanning probe microscope equipped with a nanopipette. Using a nanopipette — a tapered glass capillary with an aperture of sub-micrometer diameter — as a nozzle makes it possible to localize the discharge area of the APPJ for fine surface processing. The nanopipette can also be used as a probe for a scanning probe microscope operated with shear-force feedback control, which is capable of positioning the pipette edge in the vicinity of material surfaces for APPJ processing and imaging of the processed surface. Sub-micrometer holes and line patterns were successfully processed on a photoresist film. It was possible to control the size of the processed patterns by varying the applied pulse voltage and the distance between the pipette and the surface.

  13. A Novel Energy-Efficient Plasma Chemical Process for the Destruction of Volatile Toxic Compounds

    SciTech Connect

    Pinnaduwage, Lal A.; Ma, Cheng-YU

    1999-06-01

    Removal of low-concentrations (below several percent) of volatile toxic compounds (VTCs) from contaminated air streams is encountered at DOE waste sites in two instances: (i) Off-gases resulting from air-stripping of contaminated soil and water. (ii) Effluent from the incineration of highly-concentrated combustible hazardous wastes The objective of our research program is to develop a novel plasma chemical process for the destruction of VTC's in low-concentration waste streams.

  14. A Novel Energy Efficient Plasma Chemical Process for the Destruction of Volatile Toxic Compounds

    SciTech Connect

    Pinnaduwage, Lal A.

    2000-06-01

    The objective is to develop a novel plasma chemical process for the destruction of low concentrations (below several percent) of toxic volatile compounds from contaminated air streams. Such contaminated air streams are encountered in air stripping of highly-contaminated water and soil, and also in the incineration of combustible hazardous wastes. Our technique is based on the efficient dissociation of molecules via enhanced electron attachment to highly-excited states of the molecules produced in a glow discharge.

  15. Laws of the oxidation of carbon isotopes in plasma processes under magnetic field

    NASA Astrophysics Data System (ADS)

    Myshkin, V. F.; Bespala, E. V.; Khan, V. A.; Makarevich, S. V.

    2016-06-01

    From law of quantum mechanics it follows that spin precession phase of unpaired electron in external magnetic field cannot be determined. It uncertainty necessary take into account in different physical and chemical processes. The expression of the rate constant of a chemical reaction based on the number of discrete spin states was obtained. The equations of chemical kinetics of plasma oxidation of carbon isotopes in the magnetic field were given.

  16. Neodymium Fluorescence Quenching by Hydroxyl Groups in Phosphate Laser Glasses

    SciTech Connect

    Ehrmann, P R; Carlson, K; Campbell, J H; Click, C A; Brow, R K

    2003-09-02

    Non-radiative losses due to OH fluorescence quenching of the Nd{sup 3+} {sup 4}F{sub 3/2} state are quantified over a range of OH concentrations from 4 x 10{sup 18}/cm{sup 3} to 4 x 10{sup 20}/cm{sup 3} and Nd doping levels from 0.4 to 9 x 10{sup 20}/cm{sup 3} in two K{sub 2}O-MgO-Al{sub 2}O{sub 3}-P{sub 2}O{sub 5} metaphosphate glasses having different K/Mg ratios ({approx}1/1 and 2/1). The quenching rate is found to vary linearly with the Nd and OH concentrations as predicted by Forster-Dexter theory. However, in contrast to theory the OH quenching rate extrapolates to a non-zero value at low Nd{sup 3+} doping levels. It is proposed that at low Nd{sup 3+} concentrations the OH is correlated with Nd sites in the glass. The quenching strength of OH on a per ion basis is found to be weak compared to other common transition metal impurities (e.g. Fe{sup 2+}, Co{sup 2+}, Ni{sup 2+}, Cu{sup 2+}). Nevertheless, OH dominates the Nd quenching in phosphate glass because under most processing conditions OH is present at concentrations 10{sup 2} to 10{sup 3} greater than transition metal ion impurities. A correlation of the quenching strength of OH and common metal impurity ions with the degree of spectral overlap of the impurity absorption bands and the four {sup 4}F{sub 3/2} to {sup 4}I{sub J} transitions shows good agreement.

  17. Design and construction of Keda Space Plasma Experiment (KSPEX) for the investigation of the boundary layer processes of ionospheric depletions

    NASA Astrophysics Data System (ADS)

    Liu, Yu; Zhang, Zhongkai; Lei, Jiuhou; Cao, Jinxiang; Yu, Pengcheng; Zhang, Xiao; Xu, Liang; Zhao, Yaodong

    2016-09-01

    In this work, the design and construction of the Keda Space Plasma EXperiment (KSPEX), which aims to study the boundary layer processes of ionospheric depletions, are described in detail. The device is composed of three stainless-steel sections: two source chambers at both ends and an experimental chamber in the center. KSPEX is a steady state experimental device, in which hot filament arrays are used to produce plasmas in the two sources. A Macor-mesh design is adopted to adjust the plasma density and potential difference between the two plasmas, which creates a boundary layer with a controllable electron density gradient and inhomogeneous radial electric field. In addition, attachment chemicals can be released into the plasmas through a tailor-made needle valve which leads to the generation of negative ions plasmas. Ionospheric depletions can be modeled and simulated using KSPEX, and many micro-physical processes of the formation and evolution of an ionospheric depletion can be experimentally studied.

  18. Method to Improve Indium Bump Bonding via Indium Oxide Removal Using a Multi-Step Plasma Process

    NASA Technical Reports Server (NTRS)

    Greer, H. Frank (Inventor); Jones, Todd J. (Inventor); Vasquez, Richard P. (Inventor); Hoenk, Michael E. (Inventor); Dickie, Matthew R. (Inventor); Nikzad, Shouleh (Inventor)

    2012-01-01

    A process for removing indium oxide from indium bumps in a flip-chip structure to reduce contact resistance, by a multi-step plasma treatment. A first plasma treatment of the indium bumps with an argon, methane and hydrogen plasma reduces indium oxide, and a second plasma treatment with an argon and hydrogen plasma removes residual organics. The multi-step plasma process for removing indium oxide from the indium bumps is more effective in reducing the oxide, and yet does not require the use of halogens, does not change the bump morphology, does not attack the bond pad material or under-bump metallization layers, and creates no new mechanisms for open circuits.

  19. Hollow silicon carbide nanoparticles from a non-thermal plasma process

    NASA Astrophysics Data System (ADS)

    Coleman, Devin; Lopez, Thomas; Yasar-Inceoglu, Ozgul; Mangolini, Lorenzo

    2015-05-01

    We demonstrate the synthesis of hollow silicon carbide nanoparticles via a two-step process involving the non-thermal plasma synthesis of silicon nanoparticles, followed by their in-flight carbonization, also initiated by a non-thermal plasma. Simple geometric considerations associated with the expansion of the silicon lattice upon carbonization, in combination of the spherical geometry of the system, explain the formation of hollow nanostructures. This is in contrast with previous reports that justify the formation of hollow particles by means of out-diffusion of the core element, i.e., by the Kirkendall nanoscale effect. A theoretical analysis of the diffusion kinetics indicates that interaction with the ionized gas induces significant nanoparticle heating, allowing for the fast transport of carbon into the silicon particle and for the subsequent nucleation of the beta-silicon carbide phase. This work confirms the potential of non-thermal plasma processes for the synthesis of nanostructures composed of high-melting point materials, and suggests that such processes can be tuned to achieve morphological control.

  20. The Magnetospheric Multiscale Mission...Resolving Fundamental Processes in Space Plasmas

    NASA Technical Reports Server (NTRS)

    Curtis, S.

    1999-01-01

    The Magnetospheric Multiscale (MMS) mission is a multiple-spacecraft Solar-Terrestrial Probe designed to study the microphysics of magnetic reconnection, charged particle acceleration, and turbulence in key boundary regions of Earth's magnetosphere. These three processes, which control the flow of energy, mass, and momentum within and across plasma boundaries, occur throughout the universe and are fundamental to our understanding of astrophysical and solar system plasmas. Only in Earth's magnetosphere, however, are they readily accessible for sustained study through in-situ measurement. MMS will employ five co-orbiting spacecraft identically instrumented to measure electric and magnetic fields, plasmas, and energetic particles. The initial parameters of the individual spacecraft orbits will be designed so that the spacecraft formation will evolve into a three-dimensional configuration near apogee, allowing MMS to differentiate between spatial and temporal effects and to determine the three dimensional geometry of plasma, field, and current structures. In order to sample all of the magnetospheric boundary regions, MMS will employ a unique four-phase orbital strategy involving carefully sequenced changes in the local time and radial distance of apogee and, in the third phase, a change in orbit inclination from 10 degrees to 90 degrees. The nominal mission operational lifetime is two years. Launch is currently scheduled for 2006.

  1. Atomic Oxygen Density Measurements in a Low Pressure Textile Processing Plasma

    NASA Astrophysics Data System (ADS)

    Gomez, S.; Steen, P. G.; Graham, W. G.

    1999-10-01

    There is increasing interest in plasma processing of textile materials. Here the effect of textile materials on low pressure oxygen plasmas has been investigated. In particular laser induced fluorescence (LIF) measurements of the atomic oxygen density with and without textile samples are presented. Polypropylene and polyester samples were placed on the lower electrode of an inductively coupled Gaseous Electronic Conference (GEC) reactor. This had to be operated at low power and hence in the capacitive mode to avoid toasting the material. Operation with a bare stainless steel electrode and one loaded with the sample materials is contrasted by comparing spatially resolved LIF measurements of atomic oxygen under a wide range of pressures and powers, from a few Pa to 133 Pa, and from 10 to 300 W. Atomic oxygen densities with samples present are around one third lower than those without samples, and in both cases the atomic oxygen density increases linearly with gas pressure. Previous optical emission spectroscopy (OES) measurements indicate that plasma interaction with the substrate commences a few seconds after plasma turn on. Similar trends are observed with time resolved LIF measurements of the atomic oxygen.

  2. Gaining greater control and understanding of processing plasmas through Tailored Voltage Waveforms

    NASA Astrophysics Data System (ADS)

    Johnson, Erik

    2015-09-01

    The use of multiple harmonics of an RF frequency to generate the exciting voltage waveform for a capacitively coupled plasma has in recent years become a rich and diverse field of research. Initially proposed, observed, and named as the Electrical Asymmetry Effect by the Bochum group, the use of such Tailored Voltage Waveforms to sustain a plasma has gone beyond asymmetrizing the ion bombardment energy and flux to the electrodes. It is now clear that one can gain control over such plasma features as localization of ionization events and composition of species flux by using more counterintuitive waveforms. In this talk, progress in this field in three areas is discussed: (1) identification of new TVW's that give rise to more complex asymmetries (namely ``slope-asymmetric'' waveforms), (2) identifying applications of TVW's in plasma processing and metrology, and finally, (3) solving the technical challenges of using the technique in an industrially feasible way. The talk will focus on work done at the LPICM and LPP CNRS laboratories at the Ecole Polytechnique, but in collaboration with a number of partners from other institutes.

  3. Radicals and Non-Equilibrium Processes in Low-Temperature Plasmas

    NASA Astrophysics Data System (ADS)

    Petrović, Zoran; Mason, Nigel; Hamaguchi, Satoshi; Radmilović-Radjenović, Marija

    2007-06-01

    This volume is a selection from papers presented at the 5th EU - Japan Symposium. Unfortunately not all of the authors invited to prepare a review could finalize their papers in time for publication. Thus this book displays only a part of what has been enjoyed by the audience during the conference and what was expected to be in the book. On the other hand it provides the possibility to view some of the issues in greater detail and a chance for those who attended the meeting to revisit some of the presentations and discussion. The particular value of this symposia series is the opportunity for participants to discuss the issues confronting modern plasma physics and evolve a collaborative strategy to address these issues. The resulting synergism from having the leading researchers in this field all in the same room unfortunately could not be captured in this book but will certainly be reflected in the results presented at future symposia. The 29 invited lectures and 4 progress reports (with the addition of 10 posters) presented at the conference came from 12 different countries from 4 continents. A similar distribution is maintained in the 21 articles in this book. All the papers presented here have been refereed according to the standards of the conference and the journal, first by selecting the renowned invited speakers and selecting the topics of their presentations and later on by reviewing the articles. However we still leave the responsibility (and honors) for the contents of the papers to the authors. The papers in this book are review articles giving a summary of the already published work or presenting the work in progress that will be published in full at a later date (or both). The EU - Japan Symposia were initiated in 2003 and have been held in Japan and in Europe (so far only in European countries starting with the letter `S': Sweden, Slovakia, Serbia). The 5th EU - Japan Joint Symposium on Plasma Processing was organized in Belgrade, 6-9 March at the

  4. Determination of gasifier outlet and quench zone blockage

    SciTech Connect

    Clomburg, L.A. Jr.; Crenwelge, O.E. Jr.

    1990-10-16

    This patent describes a process for monitoring the open cross sectional area of the outlet, or a section of a quench zone or conduit proximate to and communicating with the outlet, to detect changes therein, of a gasifier operated under elevated temperature and pressure for partially oxidizing coal, while quenching synthesis gas and molten flyash particles from the gasifier and while carrying out a process for the partial oxidation of coal in the gasifier. It comprises: providing at least one first pressure transducer in the gasifier; providing at least one second pressure transducer at a locus in the quench zone proximate the outlet of the gasifier; concomitantly receiving sound pressure generated in the gasifier in both the at least one first pressure transducer and the at least one second pressure transducer, and transmitting from each of the transducers a time domain electrical signal proportionate to the amplitude of the sound pressure received by each of the respective transducers; converting the time domain signals respectively to mathematically complex signals in the frequency domain proportional to their pressure magnitudes; comparing the frequency domain signal from the at least one transducer in the quench zone to the frequency domain signal from the at least one transducer in the gasifier at a pre-selected frequency, and deriving a frequency response function from the comparison; and comparing the magnitude of the frequency response function with a predetermined value.

  5. NON-EQUILIBRIUM THERMODYNAMIC PROCESSES: SPACE PLASMAS AND THE INNER HELIOSHEATH

    SciTech Connect

    Livadiotis, G.; McComas, D. J.

    2012-04-10

    Recently, empirical kappa distribution, commonly used to describe non-equilibrium systems like space plasmas, has been connected with non-extensive statistical mechanics. Here we show how a consistent definition of the temperature and pressure is developed for stationary states out of thermal equilibrium, so that the familiar ideal gas state equation still holds. In addition to the classical triplet of temperature, pressure, and density, this generalization requires the kappa index as a fourth independent thermodynamic variable that characterizes the non-equilibrium stationary states. All four of these thermodynamic variables have key roles in describing the governing thermodynamical processes and transitions in space plasmas. We introduce a novel characterization of isothermal and isobaric processes that describe a system's transition into different stationary states by varying the kappa index. In addition, we show how the variation of temperature or/and pressure can occur through an 'iso-q' process, in which the system remains in a fixed stationary state (fixed kappa index). These processes have been detected in the proton plasma in the inner heliosheath via specialized data analysis of energetic neutral atom (ENA) observations from Interstellar Boundary Explorer. In particular, we find that the temperature is highly correlated with (1) kappa, asymptotically related to isothermal ({approx}1,000,000 K) and iso-q ({kappa} {approx} 1.7) processes; and (2) density, related to an isobaric process, which separates the 'Ribbon', P Almost-Equal-To 3.2 pdyn cm{sup -2}, from the globally distributed ENA flux, P Almost-Equal-To 2 pdyn cm{sup -2}.

  6. A Review of General Physical and Chemical Processes Related to Plasma Sources and Losses for Solar System Magnetospheres

    NASA Astrophysics Data System (ADS)

    Seki, K.; Nagy, A.; Jackman, C. M.; Crary, F.; Fontaine, D.; Zarka, P.; Wurz, P.; Milillo, A.; Slavin, J. A.; Delcourt, D. C.; Wiltberger, M.; Ilie, R.; Jia, X.; Ledvina, S. A.; Liemohn, M. W.; Schunk, R. W.

    2015-10-01

    The aim of this paper is to provide a review of general processes related to plasma sources, their transport, energization, and losses in the planetary magnetospheres. We provide background information as well as the most up-to-date knowledge of the comparative studies of planetary magnetospheres, with a focus on the plasma supply to each region of the magnetospheres. This review also includes the basic equations and modeling methods commonly used to simulate the plasma sources of the planetary magnetospheres. In this paper, we will describe basic and common processes related to plasma supply to each region of the planetary magnetospheres in our solar system. First, we will describe source processes in Sect. 1. Then the transport and energization processes to supply those source plasmas to various regions of the magnetosphere are described in Sect. 2. Loss processes are also important to understand the plasma population in the magnetosphere and Sect. 3 is dedicated to the explanation of the loss processes. In Sect. 4, we also briefly summarize the basic equations and modeling methods with a focus on plasma supply processes for planetary magnetospheres.

  7. Transport processes and distribution of plasma in the ionosphere during total solar eclipses

    NASA Astrophysics Data System (ADS)

    Chukwuma, Victor

    2016-07-01

    The effect of solar eclipse on the ionospheric F2 layer does not appear to depend only on the changes in the electron density. In this regards therefore, we have investigated the transport term process and the distribution F2 plasma during three total solar eclipses (TSE) at low- and mid-latitude. Particularly, the diurnal changes in the NmF2 and hmF2 during these spectacular events, as recorded by the ionosondes situated along the path of solar eclipses, which are within the obscuration percentage of 59-90% were investigated. Presently, our results show that NmF2 decreased during the eclipse window, as a consequence of the variation in the local solar radiation in regions under investigation. However, at mid-latitude, the distribution of F2 plasma was dominated by diffusion mechanisms which determined the height at which the F2 peak formed and were related to the changes in thermospheric composition. While at low-latitude the plasma distribution during TSE appeared to depend on combined effect of solar ionizing radiation (SIR) and the background nighttime ionospheric instabilities/irregularities mechanism. The downward/upward transport processes of the plasma appear to correspond with the drifting of the diffusion mechanisms and suffered a comparable variation with the SIR. Furthermore, at low-latitude ionosphere the transport process is controlled by the equatorial electric field. It is also observed that the eastward/westward movement of the equatorial electric field during the eclipse phase was connected to the upward/downward movement of the vertical transport. In conclusion, our results appear to indicate that eclipse effects increased with increase in latitude and the time lag decreases with increase in latitude.

  8. EDITORIAL: Atmospheric pressure non-thermal plasmas for processing and other applications

    NASA Astrophysics Data System (ADS)

    Massines, Françoise

    2005-02-01

    Interest has grown over the past few years in applying atmospheric pressure plasmas to plasma processing for the benefits this can offer to existing and potential new processes, because they do not require expensive vacuum systems and batch processing. There have been considerable efforts to efficiently generate large volumes of homogeneous atmospheric pressure non-thermal plasmas to develop environmentally friendly alternatives for surface treatment, thin film coating, sterilization, decontamination, etc. Many interesting questions have arisen that are related to both fundamental and applied research in this field. Many concern the generation of a large volume discharge which remains stable and uniform at atmospheric pressure. At this pressure, depending on the experimental conditions, either streamer or Townsend breakdown may occur. They respectively lead to micro-discharges or to one large radius discharge, Townsend or glow. However, the complexity arises from the formation of large radius streamers due to avalanche coupling and from the constriction of the glow discharge due to too low a current. Another difficulty is to visually distinguish many micro-discharges from one large radius discharge. Other questions relate to key chemical reactions in the plasma and at the surface. Experimental characterization and modelling also need to be developed to answer these questions. This cluster collects up-to-date research results related to the understanding of different discharges working at atmospheric pressure and the application to polymer surface activation and thin film coating. It presents different solutions for generating and sustaining diffuse discharges at atmospheric pressure. DC, low-frequency and radio-frequency excitations are considered in noble gases, nitrogen or air. Two specific methods developed to understand the transition from Townsend to streamer breakdown are also presented. They are based on the cross-correlation spectroscopy and an electrical

  9. ZENS. IV. Similar Morphological Changes Associated with Mass Quenching and Environment Quenching and the Relative Importance of Bulge Growth versus the Fading of Disks*

    NASA Astrophysics Data System (ADS)

    Carollo, C. M.; Cibinel, A.; Lilly, S. J.; Pipino, A.; Bonoli, S.; Finoguenov, A.; Miniati, F.; Norberg, P.; Silverman, J. D.

    2016-02-01

    We use the low-redshift Zurich Environmental Study (ZENS) catalog to study the dependence of the quenched satellite fraction at {10}10.0 {M}ȯ \\to {10}11.5 {M}ȯ , and of the morphological mix of these quenched satellites, on three different environmental parameters: group halo mass, halo-centric distance, and large-scale structure (LSS) overdensity. Within the two mass bins into which we divide our galaxy sample, the fraction of quenched satellites is more or less independent of halo mass and the surrounding LSS overdensity, but it increases toward the centers of the halos, as found in previous studies. The morphological mix of these quenched satellites is, however, constant with radial position in the halo, indicating that the well-known morphology–density relation results from the increasing fraction of quenched galaxies toward the centers of halos. If the radial variation in the quenched fraction reflects the action of two quenching processes, one related to mass and the other to environment, then the constancy with radius of the morphological outcome suggests that both have the same effect on the morphologies of the galaxies. Alternatively, mass and environment quenching may be two reflections of a single physical mechanism. The quenched satellites have larger bulge-to-total ratios (B/T) and smaller half-light radii than the star-forming satellites. The bulges in quenched satellites have very similar luminosities and surface brightness profiles, and any mass growth of the bulges associated with quenching cannot greatly change these quantities. The differences in the light-defined B/T and in the galaxy half-light radii are mostly due to differences in the disks, which have lower luminosities in the quenched galaxies. The difference in galaxy half-light radii between quenched and star-forming satellites is however larger than can be explained by uniformly fading the disks following quenching, and the quenched disks have smaller scale lengths than in star

  10. Microstructures of Melt-Processed and Spark Plasma Sintered Ceramic Waste Forms

    NASA Astrophysics Data System (ADS)

    Clark, B. M.; Tumurugoti, P.; Sundaram, S. K.; Amoroso, J. W.; Marra, J. C.; Brinkman, K. S.

    2014-12-01

    Hollandite-rich ceramic waste forms have been demonstrated to exhibit high durability while simultaneously accommodating a wide range of radionuclides in their matrices. This paper presents preliminary results on the preparation and characterization of ceramic waste forms prepared by two different methods—melt processing and spark plasma sintering (SPS). Both processes resulted in similar phase assemblages but exhibited different microstructures depending on processing method. The SPS samples exhibited fine-grained (<1 µm) and dispersed phases, whereas the melt-processed sample contained larger grains (10-20 µm) of specific phases. Additional data will need to be collected on the aqueous leaching durability and radiation resistance to evaluate each processing method for waste form performance.

  11. Surprising synthesis of nanodiamond from single-walled carbon nanotubes by the spark plasma sintering process

    NASA Astrophysics Data System (ADS)

    Mirzaei, Ali; Ham, Heon; Na, Han Gil; Kwon, Yong Jung; Kang, Sung Yong; Choi, Myung Sik; Bang, Jae Hoon; Park, No-Hyung; Kang, Inpil; Kim, Hyoun Woo

    2016-10-01

    Nanodiamond (ND) was successfully synthesized using single-walled carbon nanotubes (SWCNTs) as a pure solid carbon source by means of a spark plasma sintering process. Raman spectra and X-ray diffraction patterns revealed the generation of the cubic diamond phase by means of the SPS process. Lattice-resolved TEM images confirmed that diamond nanoparticles with a diameter of about ˜10 nm existed in the products. The NDs were generated mainly through the gas-phase nucleation of carbon atoms evaporated from the SWCNTs. [Figure not available: see fulltext.

  12. Research on modes of plasma generation in low-pressure discharge for themal radiation processes

    NASA Astrophysics Data System (ADS)

    Koval, T. V.; Lopatin, I. V.; Hung, Nguyen Bao

    2015-04-01

    In this work a theoretical research on modes of low-pressure glow discharge generation and its parameters in a large area hollow cathode are carried out. The relations describing the dependence of the burning voltage on the gas pressure and the geometry of the system were obtained. It is shown that it is possible to adjust the ion current density and burning voltage by external current injection independently of the surface area and material of the processed parts. This work also carries out a numerical study of the influence of plasma parameters on the heating of processed parts. Theoretical results are compared with experimental data.

  13. Resonant quenching of Rydberg atomic states by highly polar molecules

    NASA Astrophysics Data System (ADS)

    Narits, A. A.; Mironchuk, E. S.; Lebedev, V. S.

    2016-06-01

    The results of theoretical studies of the resonant quenching and ion-pair formation processes induced by collisions of Rydberg atoms with highly polar molecules possessing small electron affinities are reported. We elaborate an approach for describing collisional dynamics of both processes and demonstrate the predominant role of resonant quenching channel of reaction for the destruction of Rydberg states by electron-attaching molecules. The approach is based on the solution of the coupled differential equations for the transition amplitudes between the ionic and Rydberg covalent terms of a quasimolecule formed during a collision of particles. It takes into account the possibility of the dipole-bound anion decay in the Coulomb field of the positive ionic core and generalizes previous models of charge-transfer processes involving Rydberg atoms to the cases, when the multistate Landau–Zener approaches become inapplicable. Our calculations for {{Rb}}({nl}) atom perturbed by {{{C}}}2{{{H}}}4{{SO}}3, {{CH}}2{CHCN}, {{CH}}3{{NO}}2, {{CH}}3{CN}, {{{C}}}3{{{H}}}2{{{O}}}3, and {{{C}}}3{{{H}}}4{{{O}}}3 molecules show that the curves representing the dependence of the resonant quenching cross sections on the principal quantum number n are bell-shaped with the positions of maxima being shifted towards lower values of n and the peak values, {σ }{max}({{q})}, several times higher than those for the ion-pair formation, {σ }{max}({{i})}. We obtain a simple power relation between the energy of electron affinity of a molecule and the position of maximum in n-dependence of the resonant quenching cross section. It can be used as an additional means for determining small binding energies of dipole-bound anions from the experimental data on resonant quenching of Rydberg states by highly polar molecules.

  14. Resonant quenching of Rydberg atomic states by highly polar molecules

    NASA Astrophysics Data System (ADS)

    Narits, A. A.; Mironchuk, E. S.; Lebedev, V. S.

    2016-06-01

    The results of theoretical studies of the resonant quenching and ion-pair formation processes induced by collisions of Rydberg atoms with highly polar molecules possessing small electron affinities are reported. We elaborate an approach for describing collisional dynamics of both processes and demonstrate the predominant role of resonant quenching channel of reaction for the destruction of Rydberg states by electron-attaching molecules. The approach is based on the solution of the coupled differential equations for the transition amplitudes between the ionic and Rydberg covalent terms of a quasimolecule formed during a collision of particles. It takes into account the possibility of the dipole-bound anion decay in the Coulomb field of the positive ionic core and generalizes previous models of charge-transfer processes involving Rydberg atoms to the cases, when the multistate Landau-Zener approaches become inapplicable. Our calculations for {{Rb}}({nl}) atom perturbed by {{{C}}}2{{{H}}}4{{SO}}3, {{CH}}2{CHCN}, {{CH}}3{{NO}}2, {{CH}}3{CN}, {{{C}}}3{{{H}}}2{{{O}}}3, and {{{C}}}3{{{H}}}4{{{O}}}3 molecules show that the curves representing the dependence of the resonant quenching cross sections on the principal quantum number n are bell-shaped with the positions of maxima being shifted towards lower values of n and the peak values, {σ }{max}({{q})}, several times higher than those for the ion-pair formation, {σ }{max}({{i})}. We obtain a simple power relation between the energy of electron affinity of a molecule and the position of maximum in n-dependence of the resonant quenching cross section. It can be used as an additional means for determining small binding energies of dipole-bound anions from the experimental data on resonant quenching of Rydberg states by highly polar molecules.

  15. Study of selective heating at ion cyclotron resonance for the plasma separation process

    NASA Astrophysics Data System (ADS)

    Compant La Fontaine, A.; Pashkovsky, V. G.

    1995-12-01

    The plasma separation process by ion cyclotron resonance heating (ICRH) is studied both theoretically and experimentally on two devices: the first one called ERIC (Ion Cyclotron Resonance Experiment) at Saclay (France) [P. Louvet, Proceedings of the 2nd Workshop on Separation Phenomena in Liquids and Gases, Versailles, France, 1989, edited by P. Louvet, P. Noe, and Soubbaramayer (Centre d'Etudes Nucléaires de Saclay and Cité Scientifique Parcs et Technopoles, Ile de France Sud, France, 1989), Vol. 1, p. 5] and the other one named SIRENA at the Kurchatov Institute, Moscow, Russia [A. I. Karchevskii et al., Plasma Phys. Rep. 19, 214 (1993)]. The radio frequency (RF) transversal magnetic field is measured by a magnetic probe both in plasma and vacuum and its Fourier spectrum versus the axial wave number kz is obtained. These results are in agreement with the electromagnetic (EM) field calculation model based on resolution of Maxwell equations by a time-harmonic scheme studied here. Various axial boundary conditions models used to compute the EM field are considered. The RF magnetic field is weakly influenced by the plasma while the electric field components are strongly disturbed due to space-charge effects. In the plasma the transversal electric field is enhanced and the kz spectrum is narrower than in vacuum. The calculation of the resonant isotope heating is made by the Runge-Kutta method. The influence of ion-ion collisions, inhomogeneity of the static magnetic field B0, and the RF transversal magnetic field component on the ion acceleration is examined. These results are successfully compared with experiments of a minor isotope 44Ca heating measurements, made with an energy analyzer.

  16. Study of selective heating at ion cyclotron resonance for the plasma separation process

    SciTech Connect

    Compant La Fontaine, A.

    1995-12-01

    The plasma separation process by ion cyclotron resonance heating (ICRH) is studied both theoretically and experimentally on two devices: the first one called ERIC (Ion Cyclotron Resonance Experiment) at Saclay (France) [P. Louvet, {ital Proceedings} {ital of} {ital the} 2{ital nd} {ital Workshop} {ital on} {ital Separation} {ital Phenomena} {ital in} {ital Liquids} {ital and} {ital Gases}, Versailles, France, 1989, edited by P. Louvet, P. Noe, and Soubbaramayer (Centre d`Etudes Nucleaires de Saclay and Cite Scientifique Parcs et Technopoles, Ile de France Sud, France, 1989), Vol. 1, p. 5] and the other one named SIRENA at the Kurchatov Institute, Moscow, Russia [A. I. Karchevskii {ital et} {ital al}., Plasma Phys. Rep. {bold 19}, 214 (1993)]. The radio frequency (RF) transversal magnetic field is measured by a magnetic probe both in plasma and vacuum and its Fourier spectrum versus the axial wave number {ital k}{sub {ital z}} is obtained. These results are in agreement with the electromagnetic (EM) field calculation model based on resolution of Maxwell equations by a time-harmonic scheme studied here. Various axial boundary conditions models used to compute the EM field are considered. The RF magnetic field is weakly influenced by the plasma while the electric field components are strongly disturbed due to space-charge effects. In the plasma the transversal electric field is enhanced and the {ital k}{sub {ital z}} spectrum is narrower than in vacuum. The calculation of the resonant isotope heating is made by the Runge--Kutta method. The influence of ion--ion collisions, inhomogeneity of the static magnetic field {ital B}{sub 0}, and the RF transversal magnetic field component on the ion acceleration is examined. These results are successfully compared with experiments of a minor isotope {sup 44}Ca heating measurements, made with an energy analyzer. {copyright} {ital 1995} {ital American} {ital Institute} {ital of} {ital Physics}.

  17. [The quenching phenomenon or antigenic extinction].

    PubMed

    Giménez Camarasa, J M

    1985-01-01

    The new concept of "quenching" is exposed for its diffusion and Knowledge. This phenomenon occurs in nature, industry and in clinic dermatology. Doctors working in contact dermatitis suffer contradictions and paradoxic reactions due to "quenching situations". Most important bibliography on this theme is commented.

  18. On the scaling properties of quenched QED

    SciTech Connect

    Bardeen, William A.; Love, Sherwin T.; Miransky, Vladimir A.

    1990-06-17

    Critical scaling laws are studied in quenched quantum electrodynamics with induced four-fermion interactions that drive the theory to criticality. The critical exponents are calculated in the quenched, planar model and the physical picture extracted is consistent with recent results from lattice simulations. Near criticality, a composite scalar state plays an essential role in the effective dynamics.

  19. QUENCHING OF STAR FORMATION IN SLOAN DIGITAL SKY SURVEY GROUPS: CENTRALS, SATELLITES, AND GALACTIC CONFORMITY

    SciTech Connect

    Knobel, Christian; Lilly, Simon J.; Woo, Joanna; Kovač, Katarina

    2015-02-10

    We re-examine the fraction of low-redshift Sloan Digital Sky Survey satellites and centrals in which star formation has been quenched, using the environment quenching efficiency formalism that separates out the dependence of stellar mass. We show that the centrals of the groups containing the satellites are responding to the environment in the same way as their satellites (at least for stellar masses above 10{sup 10.3} M {sub ☉}), and that the well-known differences between satellites and the general set of centrals arise because the latter are overwhelmingly dominated by isolated galaxies. The widespread concept of ''satellite quenching'' as the cause of environmental effects in the galaxy population can therefore be generalized to ''group quenching''. We then explore the dependence of the quenching efficiency of satellites on overdensity, group-centric distance, halo mass, the stellar mass of the satellite, and the stellar mass and specific star formation rate (sSFR) of its central, trying to isolate the effect of these often interdependent variables. We emphasize the importance of the central sSFR in the quenching efficiency of the associated satellites, and develop the meaning of this ''galactic conformity'' effect in a probabilistic description of the quenching of galaxies. We show that conformity is strong, and that it varies strongly across parameter space. Several arguments then suggest that environmental quenching and mass quenching may be different manifestations of the same underlying process. The marked difference in the apparent mass dependencies of environment quenching and mass quenching which produces distinctive signatures in the mass functions of centrals and satellites will arise naturally, since, for satellites at least, the distributions of the environmental variables that we investigate in this work are essentially independent of the stellar mass of the satellite.

  20. Optimization of hollow cathode discharge electrode for damage free remote plasma removal process for semiconductor manufacturing

    NASA Astrophysics Data System (ADS)

    Cho, Tae S.; Han, Qing; Yang, Dongqing; Park, Soonam; Lubomirsky, Dima; Venkataraman, Shankar

    2016-05-01

    Cone-shaped hollow cathode electrode configuration for a damage free remote plasma removal process has been optimized for given pressures based on Paschen characteristic curves, voltage-current characteristics and time-resolved discharge observations as well as oxide film removal performances. Remote plasmas have been generated in two types of cone-shaped electrodes with mixtures of He, NF3, and NH3 for pressure range of 1-30 Torr. Paschen characteristic curves and voltage-current (V-I) characteristics define an operating pressure for low breakdown voltage and the hollow cathode effect to minimize the particles. Sinusoidal voltage waveform and asymmetry electrode configuration alternate the glow discharge and hollow cathode discharge modes in a cycle. The current and infrared emission intensity from the glow discharge increases together for both cone-shaped electrodes with increasing pressure, whereas the hollow cathode discharge plasma emits strong infrared only when pD condition is satisfied. For the wide cone electrode configuration, high voltage operation at higher pressure results in particle contamination on the processed wafer by high energy ion bombardment. Operating at optimum pressure for a given electrode configuration shows faster oxide etch rate with better uniformity over a whole 300 mm wafer.

  1. Low temperature plasma processing for cell growth inspired carbon thin films fabrication.

    PubMed

    Kumar, Manish; Piao, Jin Xiang; Jin, Su Bong; Lee, Jung Heon; Tajima, Satomi; Hori, Masaru; Han, Jeon Geon

    2016-09-01

    The recent bio-applications (i.e. bio-sensing, tissue engineering and cell proliferation etc.) are driving the fundamental research in carbon based materials with functional perspectives. High stability in carbon based coatings usually demands the high density deposition. However, the standard techniques, used for the large area and high throughput deposition of crystalline carbon films, often require very high temperature processing (typically >800 °C in inert atmosphere). Here, we present a low temperature (<150 °C) pulsed-DC plasma sputtering process, which enables sufficient ion flux to deposit dense unhydrogenated carbon thin films without any need of substrate-bias or post-deposition thermal treatments. It is found that the control over plasma power density and pulsed frequency governs the density and kinetic energy of carbon ions participating during the film growth. Subsequently, it controls the contents of sp(3) and sp(2) hybridizations via conversion of sp(2) to sp(3) hybridization by ion's energy relaxation. The role of plasma parameters on the chemical and surface properties are presented and correlated to the bio-activity. Bioactivity tests, carried out in mouse fibroblast L-929 and Sarcoma osteogenic (Saos-2) bone cell lines, demonstrate promising cell-proliferation in these films. PMID:27036854

  2. Silicon cells made by self-aligned selective-emitter plasma-etchback process

    SciTech Connect

    Ruby, D.S.; Schubert, W.K.; Gee, J.M.; Zaidi, S.H.

    2000-07-18

    Photovoltaic cells and methods for making them are disclosed wherein the metallized grids of the cells are used to mask portions of cell emitter regions to allow selective etching of phosphorus-doped emitter regions. The preferred etchant is SF{sub 6} or a combination of SF{sub 6} and O{sub 2}. This self-aligned selective etching allows for enhanced blue response (versus cells with uniform heavy doping of the emitter) while preserving heavier doping in the region beneath the gridlines needed for low contact resistance. Embodiments are disclosed for making cells with or without textured surfaces. Optional steps include plasma hydrogenation and PECVD nitride deposition, each of which are suited to customized applications for requirements of given cells to be manufactured. The techniques disclosed could replace expensive and difficult alignment methodologies used to obtain selectively etched emitters, and they may be easily integrated with existing plasma processing methods and techniques of the invention may be accomplished in a single plasma-processing chamber.

  3. High-speed imaging investigation of transient phenomena impacting plasma arc cutting process optimization

    NASA Astrophysics Data System (ADS)

    Boselli, M.; Colombo, V.; Ghedini, E.; Gherardi, M.; Rotundo, F.; Sanibondi, P.

    2013-06-01

    In this work, we report on the investigation of selected transient phenomena taking place in plasma arc cutting (PAC) that are relevant for process optimization. High-speed imaging diagnostics is exploited for the characterization of different technological solutions in order to provide deeper insights into torch and process design. In particular, the pilot arc start-up phase is analysed for a 250 A automatic dual-gas torch equipped with electrodes with different shapes of the initial insert recess, revealing that there is no influence of the recess depth on the time for the stabilization of the pilot arc attachment on the cathode insert. The influence of different insert materials, including Ag-Hf and Cu-Zr binary alloys, on erosion during the shut-down phase is investigated at 120 A and reduced emission of material and faster shut-down is found for alloy inserts compared with standard Hf inserts. The start-up and shut-down transients are also investigated during transferred arc operation using a modified nozzle that comprises a viewing port on one side of the nozzle, and pulsing arc behaviour inside the plasma chamber that is correlated with cathode-nozzle voltage oscillations at a frequency of 7.7 kHz is found. Finally, results regarding the influence of different plasma gas diffusers on the arc stability during the cutting initiation phase in a 100 A mono-gas manual torch are reported.

  4. Silicon cells made by self-aligned selective-emitter plasma-etchback process

    DOEpatents

    Ruby, Douglas S.; Schubert, William K.; Gee, James M.; Zaidi, Saleem H.

    2000-01-01

    Photovoltaic cells and methods for making them are disclosed wherein the metallized grids of the cells are used to mask portions of cell emitter regions to allow selective etching of phosphorus-doped emitter regions. The preferred etchant is SF.sub.6 or a combination of SF.sub.6 and O.sub.2. This self-aligned selective etching allows for enhanced blue response (versus cells with uniform heavy doping of the emitter) while preserving heavier doping in the region beneath the gridlines needed for low contact resistance. Embodiments are disclosed for making cells with or without textured surfaces. Optional steps include plasma hydrogenation and PECVD nitride deposition, each of which are suited to customized applications for requirements of given cells to be manufactured. The techniques disclosed could replace expensive and difficult alignment methodologies used to obtain selectively etched emitters, and they may be easily integrated with existing plasma processing methods and techniques of the invention may be accomplished in a single plasma-processing chamber.

  5. Vitrification of low-level waste using the plasma hearth process

    SciTech Connect

    Gillins, R.L.

    1996-03-01

    The Plasma Hearth Process (PHP) is a high temperature vitrification process using a plasma arc torch in a stationary, refractory lined chamber that destroys organics and stabilizes the residuals in a nonleaching, vitrified waste form. Plasma arc technology is an innovative technology that has exhibited commercial success, primarily in its use for production of high purity alloys and other specialty metals. The residual from the PHP provides a very stable vitrified final product of high integrity for most wastes without the need for glass formers. The final waste form will be volume-reduced to the maximum extent practical, because all organics will have been destroyed and inorganics will be in a high-density, low void-space form and little or no volume-increasing glass makers will have been added. Low volume and high integrity waste forms result in low disposal costs. The PHP technology is chiefly applicable to solid (DAW) or wet solid (sludge) wastes where volume reduction and a stabilized byproduct is desired for disposal. The technology is ideally suited for heterogeneous wastes of nearly any category that are difficult to treat by conventional thermal technologies. The application for which it is currently being developed is Department of Energy (DOE) solid mixed wastes, both low level and transuranic. DOE, through the Office of Technology Development`s Mixed Waste Focus Area (MWFA) is conducting a development and demonstration project to ready the PHP for implementation in the DOE complex.

  6. Plasma Hearth Process vitrification of DOE low-level mixed waste

    SciTech Connect

    Gillins, R.L.; Geimer, R.M.

    1995-11-01

    The Plasma Hearth Process (PHP) demonstration project is one of the key technology projects in the Department of Energy (DOE) Office of Technology Development Mixed Waste Focus Area. The PHP is recognized as one of the more promising solutions to DOE`s mixed waste treatment needs, with potential application in the treatment of a wide variety of DOE mixed wastes. The PHP is a high temperature vitrification process using a plasma arc torch in a stationary, refractory lined chamber that destroys organics and stabilizes the residuals in a nonleaching, vitrified waste form. This technology will be equally applicable to low-level mixed wastes generated by nuclear utilities. The final waste form will be volume reduced to the maximum extent practical, because all organics will have been destroyed and the inorganics will be in a high-density, low void-space form and little or no volume-increasing glass makers will have been added. Low volume and high integrity waste forms result in low disposal costs. This project is structured to ensure that the plasma technology can be successfully employed in radioactive service. The PHP technology will be developed into a production system through a sequence of tests on several test units, both non-radioactive and radioactive. As the final step, a prototype PHP system will be constructed for full-scale radioactive waste treatment demonstration.

  7. Efficient Thomson Scattering Measurement System for the Diagnostics of Processing Plasmas

    NASA Astrophysics Data System (ADS)

    Kono, Akihiro; Nakatani, Keigo

    1999-10-01

    Optical measurement of electron energy distribution function (EEDF) is desirable for the diagnostics of processing plasmas. In Thomson scattering measurements, EEDF is directly derived from the Doppler broadened profile of the laser light scattered by free electrons, but one must solve the problem of very low signal intensity due to the small scattering cross section. We have constructed an efficient Thomson scattering measurement system for the diagnostics of processing plasmas, which is capable of performing multi-channel measurement of the Doppler broadened profile without suffering from strong interference due to Rayleigh scattering and other stray scattering. The measurement system consists of a specially designed triple monochromator and an ICCD camera. The plasma is irradiated by a frequency-doubled Nd:YAG laser (532 nm). With the aid of a spatial filter between the first and second stage, the triple monochromator outputs the dispersed scattered light with the center wavelength region (532 ± 0.5 nm) eliminated, enabling multi-channel measurements with the ICCD camera in the photon-counting mode. Use of a lens system as the focusing elements in the monochromator enables high transmittance and low aberration, both serving for a high signal collection efficiency. Preliminary Thomson scattering measurements indicated a promising performance of the measurement system.

  8. Ar II Emission Processes and Emission Rate Coefficients in ASTRAL Helicon Plasmas

    NASA Astrophysics Data System (ADS)

    Boivin, R. F.; Gardner, A.; Kamar, O.; Kesterson, A.; Loch, S.; Munoz, J.; Ballance, C.

    2008-11-01

    Emission processes for Ar II line emission are described for low temperature plasmas (Te < 10 eV). It is found that Ar II emission results primarily from Ar ion ground state excitation rather than from any Ar neutral state. This suggests that Ar II emission results from stepping processes which includes ionization and then excitation of the neutral Ar atom filling the vacuum chamber. The Ar II emission rate coefficients are measured in the ASTRAL helicon plasma source using a 0.33 m monochromator and a CCD camera. ASTRAL produces Ar plasmas with the following parameters: ne = 1E11 -- 1E13 cm-3 and Te = 2 - 10 eV, B-field <= 1.3 kGauss, rf power <= 2 kWatt. RF compensated Langmuir probes are used to measure Te and ne. In this experiment, Ar II transitions are monitored as a function of Te while ne is kept constant. Experimental emission rates are obtained as a function of Te and compared to theoretical predictions. Theoretical predictions make use of the ADAS suite of codes as well as recent R-matrix electron-impact excitation calculations that includes pseudo-states contributions. Our collisional-radiative formalism assumes that the excited levels are in quasi-static equilibrium with the ground and metastable populations.

  9. Observation of nonlinear wave decay processes in the solar wind by the AMPTE IRM plasma wave experiment

    NASA Technical Reports Server (NTRS)

    Koons, H. C.; Roeder, J. L.; Bauer, O. H.; Haerendel, G.; Treumann, R.

    1987-01-01

    Nonlinear wave decay processes have been detected in the solar wind by the plasma wave experiment aboard the Active Magnetospheric Particle Tracer Explorers (AMPTE) IRM spacecraft. The main process is the generation of ultralow-frequency ion acoustic waves from the decay of Langmuir waves near the electron plasma frequency. Frequently, this is accompanied by an enhancement of emissions near twice the plasma frequency. This enhancement is most likely due to the generation of electromagnetic waves from the coalescence of two Langmuir waves. These processes occur within the electron foreshock in front of the earth's bow shock.

  10. Determining the Volume of Additive Solution and Residual Plasma in Whole Blood Filtered and Buffy Coat Processed Red Cell Concentrates

    PubMed Central

    Jordan, Andrew; Acker, Jason P.

    2016-01-01

    Summary Background Residual plasma in transfused red cell concentrates (RCCs) has been associated with adverse transfusion outcomes. Despite this, there is no consensus on the standard procedure for measuring residual plasma volume. Methods The volumes of residual plasma and additive solution were measured in RCCs processed using two separation methods: whole blood filtration (WBF) and buffy coat (BC)/RCC filtration. The concentration of mannitol and albumin in RCC components was measured using colorimetric assays. Mannitol concentration was used to calculate additive solution volume. Residual plasma volume was calculated using two methods. Results Calculated RCC supernatant volumes were much lower in BC-processed components compared to WBF-processed components (BC = 97 ± 6 ml, WBF = 109 ± 4 ml; p < 0.05). Calculated additive solution volumes were greater in WBF- than in BC-processed components (BC = 81 ± 4 ml, WBF = 105 ± 2 ml; p < 0.05). Absolute residual plasma volume varied significantly based on the calculation method used. Conclusion Disparity between plasma volume calculation methods was observed. Efforts should be made to standardize residual plasma volume measurement methods in order to accurately assess the impact of residual plasma on transfusion outcomes. PMID:27330533

  11. Challenges in the Plasma Etch Process Development in the sub-20nm Technology Nodes

    NASA Astrophysics Data System (ADS)

    Kumar, Kaushik

    2013-09-01

    For multiple generations of semiconductor technologies, RF plasmas have provided a reliable platform for critical and non-critical patterning applications. The electron temperature of processes in a RF plasma is typically several electron volts. A substantial portion of the electron population is within the energy range accessible for different types of electron collision processes, such as electron collision dissociation and dissociative electron attachment. When these electron processes occur within a small distance above the wafer, the neutral species, radicals and excited molecules, generated from these processes take part in etching reactions impacting selectivity, ARDE and micro-loading. The introduction of finFET devices at 22 nm technology node at Intel marks the transition of planar devices to 3-dimensional devices, which add to the challenges to etch process in fabricating such devices. In the sub-32 nm technology node, Back-end-of-the-line made a change with the implementation of Trench First Metal Hard Mask (TFMHM) integration scheme, which has hence gained traction and become the preferred integration of low-k materials for BEOL. This integration scheme also enables Self-Aligned Via (SAV) patterning which prevents via CD growth and confines via by line trenches to better control via to line spacing. In addition to this, lack of scaling of 193 nm Lithography and non-availability of EUV based lithography beyond concept, has placed focus on novel multiple patterning schemes. This added complexity has resulted in multiple etch schemes to enable technology scaling below 80 nm Pitches, as shown by the memory manufacturers. Double-Patterning and Quad-Patterning have become increasingly used techniques to achieve 64 nm, 56 nm and 45 nm Pitch technologies in Back-end-of-the-line. Challenges associated in the plasma etching of these multiple integration schemes will be discussed in the presentation. In collaboration with A. Ranjan, TEL Technology Center, America

  12. Excitation mechanism and thermal emission quenching of Tb ions in silicon rich silicon oxide thin films grown by plasma-enhanced chemical vapour deposition—Do we need silicon nanoclusters?

    SciTech Connect

    Podhorodecki, A. Golacki, L. W.; Zatryb, G.; Misiewicz, J.; Wang, J.; Jadwisienczak, W.; Fedus, K.

    2014-04-14

    In this work, we will discuss the excitation and emission properties of Tb ions in a Silicon Rich Silicon Oxide (SRSO) matrix obtained at different technological conditions. By means of electron cyclotron resonance plasma-enhanced chemical vapour deposition, undoped and doped SRSO films have been obtained with different Si content (33, 35, 39, 50 at. %) and were annealed at different temperatures (600, 900, 1100 °C). The samples were characterized optically and structurally using photoluminescence (PL), PL excitation, time resolved PL, absorption, cathodoluminescence, temperature dependent PL, Rutherford backscattering spectrometry, Fourier transform infrared spectroscopy and positron annihilation lifetime spectroscopy. Based on the obtained results, we discuss how the matrix modifications influence excitation and emission properties of Tb ions.

  13. A thermal equation for flame quenching

    NASA Technical Reports Server (NTRS)

    Potter, A E , Jr; Berlad, A I

    1956-01-01

    An approximate thermal equation was derived for quenching distance based on a previously proposed diffusional treatment. The quenching distance was expressed in terms of the thermal conductivity, the fuel mole fraction, the heat capacity, the rate of the rate-controlling chemical reaction, a constant that depends on the geometry of the quenching surface, and one empirical constant. The effect of pressure on quenching distance was shown to be inversely proportional to the pressure dependence of the flame reaction, with small correction necessitated by the effect of pressure on flame temperature. The equation was used with the Semenov equation for burning velocity to show that the quenching distance was inversely proportional to burning velocity and pressure at any given initial temperature and equivalence ratio.

  14. Transient Loschmidt echo in quenched Ising chains

    NASA Astrophysics Data System (ADS)

    Lupo, Carla; Schiró, Marco

    2016-07-01

    We study the response to sudden local perturbations of highly excited quantum Ising spin chains. The key quantity encoding this response is the overlap between time-dependent wave functions, which we write as a transient Loschmidt Echo. Its asymptotics at long time differences contain crucial information about the structure of the highly excited nonequilibrium environment induced by the quench. We compute the echo perturbatively for a weak local quench but for arbitrarily large global quench, using a cumulant expansion. Our perturbative results suggest that the echo decays exponentially, rather than power law as in the low-energy orthogonality catastrophe, a further example of quench-induced decoherence already found in the case of quenched Luttinger liquids. The emerging decoherence scale is set by the strength of the local potential and the bulk excitation energy.

  15. QUENCH STUDIES AND PREHEATING ANALYSIS OF SEAMLESS

    SciTech Connect

    Palczewski, Ari; Geng, Rongli; Eremeev, Grigory

    2013-09-01

    One of the alternative manufacturing technologies for SRF cavities is hydroforming from seamless tubes. Although this technology has produced cavities with gradient and Q-values comparable to standard EBW/EP cavities, a few questions remain. One of these questions is whether the quench mechanism in hydroformed cavities is the same as in standard electron beam welded cavities. Towards this effort Jefferson Lab performed quench studies on 2 9 cell seamless hydroformed cavities. These cavities include DESY's - Z163 and Z164 nine-cell cavities hydroformed at DESY. Initial Rf test results Z163 were published in SRF2011. In this report we will present post JLAB surface re-treatment quench studies for each cavity. The data will include OST and T-mapping quench localization as well as quench location preheating analysis comparing them to the observations in standard electron beam welded cavities.

  16. Numerical study of plasma generation process and internal antenna heat loadings in J-PARC RF negative ion source

    NASA Astrophysics Data System (ADS)

    Shibata, T.; Nishida, K.; Mochizuki, S.; Mattei, S.; Lettry, J.; Hatayama, A.; Ueno, A.; Oguri, H.; Ohkoshi, K.; Ikegami, K.; Takagi, A.; Asano, H.; Naito, F.

    2016-02-01

    A numerical model of plasma transport and electromagnetic field in the J-PARC (Japan Proton Accelerator Research Complex) radio frequency ion source has been developed to understand the relation between antenna coil heat loadings and plasma production/transport processes. From the calculation, the local plasma density increase is observed in the region close to the antenna coil. Electrons are magnetized by the magnetic field line with absolute magnetic flux density 30-120 Gauss which leads to high local ionization rate. The results suggest that modification of magnetic configuration can be made to reduce plasma heat flux onto the antenna.

  17. Numerical study of plasma generation process and internal antenna heat loadings in J-PARC RF negative ion source.

    PubMed

    Shibata, T; Nishida, K; Mochizuki, S; Mattei, S; Lettry, J; Hatayama, A; Ueno, A; Oguri, H; Ohkoshi, K; Ikegami, K; Takagi, A; Asano, H; Naito, F

    2016-02-01

    A numerical model of plasma transport and electromagnetic field in the J-PARC (Japan Proton Accelerator Research Complex) radio frequency ion source has been developed to understand the relation between antenna coil heat loadings and plasma production/transport processes. From the calculation, the local plasma density increase is observed in the region close to the antenna coil. Electrons are magnetized by the magnetic field line with absolute magnetic flux density 30-120 Gauss which leads to high local ionization rate. The results suggest that modification of magnetic configuration can be made to reduce plasma heat flux onto the antenna. PMID:26932010

  18. Influence of renormalization shielding on the electron-impact ionization process in dense partially ionized plasmas

    SciTech Connect

    Song, Mi-Young; Yoon, Jung-Sik; Jung, Young-Dae

    2015-04-15

    The renormalization shielding effects on the electron-impact ionization of hydrogen atom are investigated in dense partially ionized plasmas. The effective projectile-target interaction Hamiltonian and the semiclassical trajectory method are employed to obtain the transition amplitude as well as the ionization probability as functions of the impact parameter, the collision energy, and the renormalization parameter. It is found that the renormalization shielding effect suppresses the transition amplitude for the electron-impact ionization process in dense partially ionized plasmas. It is also found that the renormalization effect suppresses the differential ionization cross section in the peak impact parameter region. In addition, it is found that the influence of renormalization shielding on the ionization cross section decreases with an increase of the relative collision energy. The variations of the renormalization shielding effects on the electron-impact ionization cross section are also discussed.

  19. Defective iron-oxide nanoparticles synthesised by high temperature plasma processing: a magnetic characterisation versus temperature.

    PubMed

    Balasubramanian, C; Joseph, B; Orpe, P B; Saini, N L; Mukherjee, S; Dziedzic-Kocurek, K; Stanek, J; Di Gioacchino, D; Marcelli, A

    2016-11-01

    Magnetic properties and phase compositions of iron-oxide nanoparticles synthesised by a high temperature arc plasma route have been investigated by Mössbauer spectroscopy and high harmonic magnetic AC susceptibility measurements, and correlated with morphological and structural properties for different synthesis conditions. The Mössbauer spectra precisely determined the presence of different iron-oxide fractions in the investigated nanoparticles, while the high harmonic magnetic susceptibility measurements revealed the occurrence of metastable magnetic phases evolving in temperature and time. This study illustrates magnetic properties and dynamics of the magnetic configurations of iron-oxide nanoparticles grown by high temperature plasma, a process less explored so far but extremely useful for synthesising large numbers of nanoparticles for industrial applications. PMID:27668803

  20. Fabrication of Nanosized Lanthanum Zirconate Powder and Deposition of Thermal Barrier Coating by Plasma Spray Process

    NASA Astrophysics Data System (ADS)

    Mishra, S. K.; Jagdeesh, N.; Pathak, L. C.

    2016-07-01

    The present manuscript discusses our findings on fabrication of nanosized lanthanum zirconate powder for thermal barrier coating application and its coating by plasma spray on nickel-based superalloy substrate. Single-phase La2Zr2O7 coating of thickness of the order of 45 µm on the Ni-Cr-Al bond coat coated Ni-based superalloy substrate was deposited by plasma spray process. The layers at the interface did not show spallation and inter diffusion was very less. The microstructure, interface, porosity, and mechanical properties of different layers are investigated. The lanthanum zirconate hardness and modulus were 10.5 and 277 GPa, respectively. The load depth curve for lanthanum zirconate showed good elastic recovery around 74%.