Science.gov

Sample records for gas operational discharges

  1. Operation of Ferroelectric Plasma Sources in a Gas Discharge Mode

    SciTech Connect

    A. Dunaevsky; N.J. Fisch

    2004-03-08

    Ferroelectric plasma sources in vacuum are known as sources of ablative plasma, formed due to surface discharge. In this paper, observations of a gas discharge mode of operation of the ferroelectric plasma sources (FPS) are reported. The gas discharge appears at pressures between approximately 20 and approximately 80 Torr. At pressures of 1-20 Torr, there is a transition from vacuum surface discharge to the gas discharge, when both modes coexist and the surface discharges sustain the gas discharge. At pressures between 20 and 80 Torr, the surface discharges are suppressed, and FPS operate in pure gas discharge mode, with the formation of almost uniform plasma along the entire surface of the ceramics between strips. The density of the expanding plasma is estimated to be about 1013 cm-3 at a distance of 5.5 mm from the surface. The power consumption of the discharge is comparatively low, making it useful for various applications. This paper also presents direct measurements of the yield of secondary electron emission from ferroelectric ceramics, which, at low energies of primary electrons, is high and dependent on the polarization of the ferroelectric material

  2. Hydrogen discharges operating at atmospheric pressure in a semiconductor gas discharge system

    NASA Astrophysics Data System (ADS)

    Aktas, K.; Acar, S.; Salamov, B. G.

    2011-08-01

    Analyses of physical processes which initiate electrical breakdown and spatial stabilization of current and control it with a photosensitive cathode in a semiconductor gas discharge system (SGDS) are carried out in a wide pressure range up to atmospheric pressure p, interelectrode distance d and diameter D of the electrode areas of the semiconductor cathode. The study compares the breakdown and stability curves of the gas discharge in the planar SGDS where the discharge gap is filled with hydrogen and air in two cases. The impact of the ionizing component of the discharge plasma on the control of the stable operation of the planar SGDS is also investigated at atmospheric pressure. The loss of stability is primarily due to modification of the semiconductor-cathode properties on the interaction with low-energy hydrogen ions and the formation of a space charge of positive ions in the discharge gap which changes the discharge from Townsend to glow type. The experimental results show that the discharge current in H2 is more stable than in air. The breakdown voltages are measured for H2 and air with parallel-plane electrodes, for pressures between 28 and 760 Torr. The effective secondary electron emission (SEE) coefficient is then determined from the breakdown voltage results and compared with the experimental results. The influence of the SEE coefficient is stated in terms of the differences between the experimental breakdown law.

  3. INTENSE ENERGETIC GAS DISCHARGE

    DOEpatents

    Luce, J.S.

    1960-03-01

    A method and apparatus for initiating and sustaining an energetic gas arc discharge are described. A hollow cathode and a hollow anode are provided. By regulating the rate of gas flow into the interior of the cathode, the arc discharge is caused to run from the inner surface of the cathode with the result that adequate space-charge neutralization is provided inside the cathode but not in the main arc volume. Thus, the gas fed to the cathode is substantially completely ionized before it leaves the cathode, with the result that an energetic arc discharge can be maintained at lower operating pressures.

  4. Radiofrequency gas plasma (glow discharge) disinfection of dental operative instruments, including handpieces.

    PubMed

    Baier, R E; Carter, J M; Sorensen, S E; Meyer, A E; McGowan, B D; Kasprzak, S A

    1992-01-01

    The radiofrequency-stimulated argon gas plasma (glow discharge) technique, already well-known for surface cleaning and activation of adhesion, was investigated for determination of its separate potential for rapid disinfection of dental operative instruments. Disinfection effectiveness was judged from diminished post-treatment recovery of viable organisms from the instruments agitated in saline. Streptococcus salivarius, Bacillus stearothermophilus, and Escherichia coli were used as primary contaminant organisms, dried from gelatin-thickened laboratory cultures onto the instruments and not subjected to any preliminary cleaning steps. Significant disinfection was obtained, with no sensible temperature increases, in under 10 minutes in laboratory apparatus consuming fewer than 5 Watts of power per cycle. Also, clinically used and deliberately-saliva-contaminated high-speed handpieces were gas-discharge-treated, with their resultant rapid disinfection noted by complete suppression of the viability of any transferred natural contaminant organisms within two minutes. With regard to preservation of instrument quality, it was also shown that this low-temperature gas-discharge method provides the noted substantial disinfection without deterioration of sharp edges. Work now in progress suggests that the method can provide cool, rapid, and complete sterilization when hydrogen peroxide vapors are present in the gas plasma used for treatment of instruments first given the normally recommended thorough pre-cleaning. PMID:1289559

  5. GAS DISCHARGE DEVICES

    DOEpatents

    Arrol, W.J.; Jefferson, S.

    1957-08-27

    The construction of gas discharge devices where the object is to provide a gas discharge device having a high dark current and stabilized striking voltage is described. The inventors have discovered that the introduction of tritium gas into a discharge device with a subsequent electrical discharge in the device will deposit tritium on the inside of the chamber. The tritium acts to emit beta rays amd is an effective and non-hazardous way of improving the abovementioned discharge tube characteristics

  6. Enhancement of the EUV emission of a metallic capillary discharge operated with argon ambient gas

    SciTech Connect

    Chan, L. S. Tan, D. Saboohi, S. Yap, S. L. Wong, C. S.

    2014-03-05

    In this work, the metallic capillary discharge is operated with two different ambients: air and argon. In the experiments reported here, the chamber is first evacuated to 10{sup −5} mbar. The discharge is initiated by the transient hollow cathode effect generated electron beam, with either air ambient or argon ambient at 10{sup −4} mbar. The bombardment of electron beam at the tip of the stainless steel anode gives rise to a metallic vapor, which is injected into the capillary and initiates the main discharge through the capillary. The EUV emission is measured for different discharge voltages for both conditions and compared. It is found that the metallic capillary discharge with argon ambientis able to produce higher EUV energy compared to that with air ambient.

  7. GAS DISCHARGE DEVICES

    DOEpatents

    Jefferson, S.

    1958-11-11

    An apparatus utilized in introducing tritium gas into envelope of a gas discharge device for the purpose f maintaining the discharge path in ionized condition is described. ln addition to the cathode and anode, the ischarge device contains a zirconium or tantalum ilament arranged for external excitation and a metallic seed containing tritium, and also arranged to have a current passed through it. Initially, the zirconium or tantalum filament is vaporized to deposit its material adjacent the main discharge region. Then the tritium gas is released and, due to its affinity for the first released material, it deposits in the region of the main discharge where it is most effective in maintaining the discharge path in an ionized condition.

  8. (Gas discharges and applications)

    SciTech Connect

    Sauers, I.

    1988-10-04

    The traveler attended the Ninth International Conference on Gas Discharges and Their Applications, which was held in Venice, Italy, on September 19--23, 1988; presented two papers, (1) Ion Chemistry in SF{sub 6} Corona'' and (2) Production of S{sub 2}F{sub 10} by SF{sub 6} Spark Discharge''; and participated in numerous discussions with conference participants on gas discharges related to his work on SF{sub 6}. The traveler visited the Centre de Physique Atomique at the University Paul Sabatier in Toulouse, France, to discuss with Dr. J. Casanovas his work on SF{sub 6} decomposition. Following that visit, the traveler visited the Laboratoire de Photoelectricite at the University of Dijon to discuss with Dr. J.-P. Goudonnet his work on surface studies and on the use of tunneling electron spectroscopy for the chemical analysis of surfaces.

  9. 46 CFR 153.964 - Discharge by gas pressurization.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Discharge by gas pressurization. 153.964 Section 153.964... CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Operations Cargo Transfer Procedures § 153.964 Discharge by gas pressurization. The person in charge of cargo transfer may...

  10. 46 CFR 153.964 - Discharge by gas pressurization.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Discharge by gas pressurization. 153.964 Section 153.964... CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Operations Cargo Transfer Procedures § 153.964 Discharge by gas pressurization. The person in charge of cargo transfer may...

  11. 46 CFR 153.964 - Discharge by gas pressurization.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Discharge by gas pressurization. 153.964 Section 153.964... CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Operations Cargo Transfer Procedures § 153.964 Discharge by gas pressurization. The person in charge of cargo transfer may...

  12. 46 CFR 154.1838 - Discharge by gas pressurization.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Discharge by gas pressurization. 154.1838 Section 154... SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Operations § 154.1838 Discharge by gas pressurization. The person in charge of cargo transfer may not authorize cargo discharge...

  13. 46 CFR 154.1838 - Discharge by gas pressurization.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Discharge by gas pressurization. 154.1838 Section 154... SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Operations § 154.1838 Discharge by gas pressurization. The person in charge of cargo transfer may not authorize cargo discharge...

  14. 46 CFR 154.1838 - Discharge by gas pressurization.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Discharge by gas pressurization. 154.1838 Section 154... SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Operations § 154.1838 Discharge by gas pressurization. The person in charge of cargo transfer may not authorize cargo discharge...

  15. 46 CFR 153.964 - Discharge by gas pressurization.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Discharge by gas pressurization. 153.964 Section 153.964 Shipping COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) CERTAIN BULK DANGEROUS CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Operations Cargo Transfer Procedures § 153.964 Discharge by...

  16. High-repetition-rate short-pulse gas discharge.

    PubMed

    Tulip, J; Seguin, H; Mace, P N

    1979-09-01

    A high-average-power short-pulse gas discharge is described. This consists of a volume-preionized transverse discharge of the type used in gas lasers driven by a Blumlein energy storage circuit. The Blumlein circuit is fabricated from coaxial cable, is pulse-charged from a high-repetition-rate Marx-bank generator, and is switched by a high-repetition-rate segmented rail gap. The operation of this discharge under conditions typical of rare-gas halide lasers is described. A maximum of 900 pps was obtained, giving a power flow into the discharge of 30 kW. PMID:18699678

  17. 46 CFR 154.1838 - Discharge by gas pressurization.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... SAFETY STANDARDS FOR SELF-PROPELLED VESSELS CARRYING BULK LIQUEFIED GASES Operations § 154.1838 Discharge... pressurizing medium is the cargo vapor or a nonflammable, nontoxic gas that is inert with the cargo; and...

  18. The effect of the operation modes of a gas discharge low-pressure amalgam lamp on the intensity of generation of 185 nm UV vacuum radiation

    SciTech Connect

    Vasilyak, L. M.; Drozdov, L. A. Kostyuchenko, S. V.; Sokolov, D. V.; Kudryavtsev, N. N.; Sobur, D. A.

    2011-12-15

    The effect of the discharge current, mercury vapor pressure, and the inert gas pressure on the intensity and efficiency of the 185 nm line generation are considered. The spectra of the UV radiation (vacuum ultraviolet) transmission by protective coatings from the oxides of rare earth metals and aluminum are investigated.

  19. GAS DISCHARGE SWITCH EVALUATION FOR RHIC BEAM ABORT KICKER APPLICATION.

    SciTech Connect

    ZHANG,W.; SANDBERG,J.; SHELDRAKE,R.; PIRRIE,C.

    2002-06-30

    A gas discharge switch EEV HX3002 is being evaluated at Brookhaven National Laboratory as a possible candidate of RHIC Beam Abort Kicker modulator main switch. At higher beam energy and higher beam intensity, the switch stability becomes very crucial. The hollow anode thyratron used in the existing system is not rated for long reverse current conduction. The reverse voltage arcing caused thyratron hold-off voltage de-rating has been the main limitation of the system operation. To improve the system reliability, a new type of gas discharge switch has been suggested by Marconi Applied Technology for its reverse conducting capability.

  20. Multiplex electric discharge gas laser system

    NASA Technical Reports Server (NTRS)

    Laudenslager, James B. (Inventor); Pacala, Thomas J. (Inventor)

    1987-01-01

    A multiple pulse electric discharge gas laser system is described in which a plurality of pulsed electric discharge gas lasers are supported in a common housing. Each laser is supplied with excitation pulses from a separate power supply. A controller, which may be a microprocessor, is connected to each power supply for controlling the application of excitation pulses to each laser so that the lasers can be fired simultaneously or in any desired sequence. The output light beams from the individual lasers may be combined or utilized independently, depending on the desired application. The individual lasers may include multiple pairs of discharge electrodes with a separate power supply connected across each electrode pair so that multiple light output beams can be generated from a single laser tube and combined or utilized separately.

  1. Metal hydrides studied in gas discharge tube

    NASA Astrophysics Data System (ADS)

    Bozhinova, I.; Kolev, S.; Popov, Tsv.; Pashov, A.; Dimitrova, M.

    2016-05-01

    A novel construction of gas discharge tube has been tested for production of high densities of metal hydrydes. Its performance turned out to be comparable with the existing sources of the same type and even better. First results of the tests on NiH are reported and critically analysed. Plans for future modifiaction of the construction and application of the tube are discussed.

  2. Environmental and economic assessment of discharges from Gulf of Mexico Region oil and gas operation. Quarterly technical progress report, 1 October--31 December 1994

    SciTech Connect

    Gettleson, D.A.

    1995-01-18

    Task 3 (Environmental Field Sampling and Analysis of NORM, Heavy Metals, and Organics) work included analyses of samples. Task 4 (Monitoring of the Recovery of Impacted Wetland and Open Bay Produced Water Discharge Sites in Coastal Louisiana and Texas) activities involved the continued analyses of samples and field sampling at Bay de Chene. Task 5 (Assessment of Economic Impacts of Offshore and Coastal Discharge Requirements on Present and Future Operations in the Gulf of Mexico Region) activities included preparing a draft final report. Task 6 (Synthesis of Gulf of Mexico Seafood Consumption and Use Patterns) work also involved preparing a draft final report. Task 7 (Technology Transfer Plan) activities included a presentation at the Minerals Management Service Information Transfer Meeting for the Gulf of Mexico OCS Region. Task 8 (Project Management and Deliverables) activities involved the submission of the necessary reports and routine management.

  3. METHOD AND APPARATUS FOR PRODUCING INTENSE ENERGETIC GAS DISCHARGES

    DOEpatents

    Bell, P.R.; Luce, J.S.

    1960-01-01

    A device for producing an energetic gas arc discharge employing the use of gas-fed hollow cathode and anode electrodes is reported. The rate of feed of the gas to the electrodes is regulated to cause complete space charge neutralization to occur within the electrodes. The arc discharge is closely fitted within at least one of the electrodes so tint the gas fed to this electrode is substantially completely ionized before it is emitted into the vacuum chamber. It is this electrode design and the axial potential gradient that exists in the arc which permits the arc to be operated in low pressures and at volthges and currents that permit the arc to be energetic. The use of the large number of energetic ions that are accelerated toward the cathode as a propulsion device for a space vehicle is set forth.

  4. Research on Modern Gas Discharge Light Sources

    NASA Astrophysics Data System (ADS)

    Born, M.; Markus, T.

    This article gives an overview of today's gas discharge light sources and their application fields with focus on research aspects. In Sect. 15.1 of this chapter, an introduction to electric light sources, the lighting market and related research topics is outlined. Due to the complexity of the subject, we have focused on selected topics in the field of high intensity discharge (HID) lamps since these represent an essential part of modern lamp research. The working principle and light technical properties of HID lamps are described in Sect. 15.2. Physical and thermochemical modelling procedures and tools as well as experimental analysis are discussed in Sects. 15.3 and 15.4, respectively. These tools result in a detailed scientific insight into the complexity of real discharge lamps. In particular, analysis and modelling are the keys for further improvement and development of existing and new products.

  5. Pre-breakdown evaluation of gas discharge mechanisms in microgaps

    SciTech Connect

    Semnani, Abbas; Peroulis, Dimitrios; Venkattraman, Ayyaswamy; Alexeenko, Alina A.

    2013-04-29

    The individual contributions of various gas discharge mechanisms to total pre-breakdown current in microgaps are quantified numerically. The variation of contributions of field emission and secondary electron emission with increasing electric field shows contrasting behavior even for a given gap size. The total current near breakdown decreases rapidly with gap size indicating that microscale discharges operate in a high-current, low-voltage regime. This study provides the first such analysis of breakdown mechanisms and aids in the formulation of physics-based theories for microscale breakdown.

  6. Environmental and economic assessment of discharges from Gulf of Mexico Region Oil and Gas Operations. Quarterly technical progress report, 1 October--31 December 1993

    SciTech Connect

    Gettleson, D.A.

    1994-01-28

    Task 2 (Preparation of the Sampling and Analysis Plan) activities involved the incorporation of the offshore site selection process into the Sampling and Analysis Plan. Task 3 (Environmental Field Sampling and Analysis of NORM, Heavy Metals, and Organics) work included making decisions on tissue analyses and performing analyses of water and sediment samples. Task 4 (Monitoring of the Recovery of Impacted Wetland and Open Bay Produced Water Discharge Sites in Coastal Louisiana and Texas) activities involved the completion of the spring benthos samples collection on pre-termination samples at Four Isle Dome and the first post-termination samples at Delacroix Island. Task 5 (Assessment of Economic Impacts of Offshore and Coastal Discharge Requirements on Present and Future Operations in the Gum of Mexico Region) activities included continued work on development of a base case production forecast, modeling future production, and determining economic impact of treatment technologies. Task 6 (Synthesis of Gulf of Mexico Seafood Consumption and Use Patterns) work involved the completion of the fall survey season and the initiation of the survey data assembly. Task 7 (Technology Transfer Plan) activities included presentations at the Society of Environmental Toxicology and Chemistry annual meeting and Minerals Management Service Information Transfer Meeting. Task 8 (Project Management and Deliverables) activities involved the submission of the necessary reports and routine management.

  7. Environmental and economic assessment of discharges from Gulf of Mexico Region oil and gas operations. Quarterly technical progress report, 23 June 1992--30 September 1992

    SciTech Connect

    Gettleson, D.A.

    1992-11-10

    A Sampling and Analysis Plan was prepared and submitted to a Scientific Review Committee for comment. Substantial comments relative to study objectives, sampling design, and sampling periods coupled with the passage of Hurricane Andrew precluded the scheduled initiation of sampling at offshore and coastal sites (Tasks 3 -- Environmental Field Sampling and Analysis of Naturally Occurring Radioactive Materials (NORM), Heavy Metals, and Organics and 4 -- Monitoring of the Recovery of Impacted Wetland and Open Bay Produced Water Discharge Sites in Coastal Louisiana and Texas). A proposed revised schedule has been prepared for Tasks 3 and 4. Task 5 (Assessment of Economic Impacts of Offshore and Coastal Discharge Requirements on Present and Future Operations in the Gulf of Mexico Region), activities have involved identification and collection of the necessary data for the economic analysis. Task 6 (Synthesis of Gulf of Mexico Region Consumption and Use Patterns), activities have included near completion of the literature review and a reevaluation of the data collection efforts relative to the wholesaler, process plant, and restaurant components. Task 7 (Technology Transfer Plan), work has been delayed due to the Tasks 3 and 4 delay and cancellation of the annual US Minerals Management Service Gulf of Mexico Region Information Transfer Meeting.

  8. Physical processes in grid control gas discharge device Tacitron

    NASA Astrophysics Data System (ADS)

    Arefiev, Alexander; Vereschagin, Nicolay; Kruglov, Sergey

    2003-10-01

    of all stages of the distinguishing depends on: - pressure of the gas; - magnitude of the interrupting current (the concentration of electrons and ions in the discharge space); - magnitude of the voltage on the anode and grid; - sort of the filling gas - type of the load. According to the results of the investigation some recomendations on the operating of the tacitron in pulse power units were done.

  9. Sounding experiments of high pressure gas discharge

    SciTech Connect

    Biele, Joachim K.

    1998-07-10

    A high pressure discharge experiment (200 MPa, 5{center_dot}10{sup 21} molecules/cm{sup 3}, 3000 K) has been set up to study electrically induced shock waves. The apparatus consists of the combustion chamber (4.2 cm{sup 3}) to produce high pressure gas by burning solid propellant grains to fill the electrical pump chamber (2.5 cm{sup 3}) containing an insulated coaxial electrode. Electrical pump energy up to 7.8 kJ at 10 kV, which is roughly three times of the gas energy in the pump chamber, was delivered by a capacitor bank. From the current-voltage relationship the discharge develops at rapidly decreasing voltage. Pressure at the combustion chamber indicating significant underpressure as well as overpressure peaks is followed by an increase of static pressure level. These data are not yet completely understood. However, Lorentz forces are believed to generate pinching with subsequent pinch heating, resulting in fast pressure variations to be propagated as rarefaction and shock waves, respectively. Utilizing pure axisymmetric electrode initiation rather than often used exploding wire technology in the pump chamber, repeatable experiments were achieved.

  10. Low-voltage gas-discharge device

    DOEpatents

    Kovarik, V.J.; Hershcovitch, A.; Prelec, K.

    1982-06-08

    An electronic device of the type wherein current flow is conducted by an ionized gas comprising a cathode of the type heated by ionic bombardment, an anode, means for maintaining a predetermined pressure in the region between the anode and the cathode and means for maintaining a field in the region is described. The field, which is preferably a combined magnetic and electric field, is oriented so that the mean distance traveled by electrons before reaching the anode is increased. Because of this increased distance traveled electrons moving to the anode will ionize a large number of gas atoms, thus reducing the voltage necessary to initiate gas breakdown. In a preferred embodiment the anode is a main hollow cathode and the cathode is a smaller igniter hollow cathode located within and coaxial with the main hollow cathode. An axial magnetic field is provided in the region between the hollow cathodes in order to facilitate gas breakdown in that region and initiate plasma discharge from the main hollow cathode.

  11. Flue-gas cleaning using heterogeneously pulsed discharge

    NASA Astrophysics Data System (ADS)

    Yankelevitch, E.; Bystritskii, Vitaly M.; Sinebryukhov, A. V.; Akishev, Yurii

    1995-03-01

    A new promising electro physical method for cleaning flue gases from sulfur and nitrogen oxides has been proposed. This method is based on the initiation of repetitive arc micro discharges in an air-water mixture. The report gives a description of the setup used in an experimental verification of the method, the experimental results obtained, and the results of their analyses. It has been demonstrated that the proposed method has some advantages over other electro physical methods, such as simplicity to realize and operability in a highly humidified gas stream, which substantially extends the realize of its possible applications. The energy required to remove harmful impurity is 200 eV/mol and 23 eV/mol for gas mixtures with NO and SO2, respectively, which is an excellent result for an electro physical method of gas cleaning.

  12. Discharge source with gas curtain for protecting optics from particles

    DOEpatents

    Fornaciari, Neal R.; Kanouff, Michael P.

    2004-03-30

    A gas curtain device is employed to deflect debris that is generated by an extreme ultraviolet and soft x-ray radiation discharge source such as an electric discharge plasma source. The gas curtain device projects a stream of gas over the path of the radiation to deflect debris particles into a direction that is different from that of the path of the radiation. The gas curtain can be employed to prevent debris accumulation on the optics used in photolithography.

  13. Self-organization of intense light within erosive gas discharges

    NASA Astrophysics Data System (ADS)

    Torchigin, V. P.; Torchigin, A. V.

    2007-01-01

    Process of appearance of fire balls at gas discharges is considered. It is shown that the intense white light radiated by atoms excited at gas discharge is subject to self-organization in such a way that miniature ball lightnings appear.

  14. Power supply for negative impedance gas discharge lasers

    SciTech Connect

    Bees, G.L.

    1987-12-29

    An adjustable constant current power supply for a negative impedance gas discharge laser is described comprising: means for providing constant output of current, means connected between the constant current providing means and the gas discharge laser for matching the current output of the constant current providing means with lasing requirements of the gas discharge laser, the constant current providing means providing electrical energy to pump the gas discharge laser; and means electrically connected to the constant current providing means for feeding a variable controlled voltage to the constant current providing means the variable voltage altering the constant output of current over a preselected range feedback circuit means for providing a control signal to the variably controlled voltage feeding means; such that output power of the gas discharge laser varies with the output of current from the current providing means.

  15. Composite body for gas discharge lamp

    SciTech Connect

    Driessen, A. J. G. C.; Geertsema, E. B.; Oomen, J. J. C.; Rouwendal, J. W.

    1985-02-26

    Composite body, a gas discharge lamp having a sodium pressure from 300-600 torr in particular, having an envelope of densely sintered aluminium oxide or of other sodium vapor-resistant materials and a feed-through member of tantalum, niobium or other metals equivalent thereto, The bonding material consisting of a finely dispersed polycrystalline product having a composition in mole % between the following limits: Al/sub 2/O/sub 3/-5-70 at least one oxide chosen from Sc/sub 2/O/sub 3/ and Ti/sub 2/O /SUB x/ , wherein 2

  16. Sensitive glow discharge ion source for aerosol and gas analysis

    DOEpatents

    Reilly, Peter T. A.

    2007-08-14

    A high sensitivity glow discharge ion source system for analyzing particles includes an aerodynamic lens having a plurality of constrictions for receiving an aerosol including at least one analyte particle in a carrier gas and focusing the analyte particles into a collimated particle beam. A separator separates the carrier gas from the analyte particle beam, wherein the analyte particle beam or vapors derived from the analyte particle beam are selectively transmitted out of from the separator. A glow discharge ionization source includes a discharge chamber having an entrance orifice for receiving the analyte particle beam or analyte vapors, and a target electrode and discharge electrode therein. An electric field applied between the target electrode and discharge electrode generates an analyte ion stream from the analyte vapors, which is directed out of the discharge chamber through an exit orifice, such as to a mass spectrometer. High analyte sensitivity is obtained by pumping the discharge chamber exclusively through the exit orifice and the entrance orifice.

  17. Radionuclides, Metals, and Hydrocarbons in Oil and Gas Operational Discharges and Environmental Samples Associated with Offshore Production Facilities on the Texas/Louisiana Continental Shelf with an Environmental Assessment of Metals and Hydrocarbons

    SciTech Connect

    Continental Shelf Associates, Inc.

    1999-08-16

    This report presents concentrations of radionuclides, metals, and hydrocarbons in samples of produced water and produced sand from oil and gas production platforms located offshore Texas and Louisiana. Concentrations in produced water discharge plume/receiving water, ambient seawater, sediment, interstitial water, and marine animal tissue samples collected in the vicinity of discharging platforms and reference sites distant from discharges are also reported and discussed. An environmental risk assessment is made on the basis of the concentrations of metals and hydrocarbons determined in the samples.

  18. Radionuclides, Metals, and Hydrocarbons in Oil and Gas Operational Discharges and Environmental Samples Associated with Offshore Production Facilities on the Texas/Louisiana Continental Shelf with an Environmental Assessment of Metals and Hydrocarbons.

    SciTech Connect

    1997-06-01

    This report presents concentrations of radionuclides, metals, and hydrocarbons in samples of produced water and produced sand from oil and gas production platforms located offshore Texas and Louisiana. concentrations in produced water discharge plume / receiving water, ambient seawater, sediment, interstitial water, and marine animal tissue samples collected in the vicinity of discharging platforms and reference sites distant from discharges are also reported and discussed. An environmental risk assessment is made on the basis of the concentration of metals and hydrocarbons determined in the samples.

  19. Electric-discharge gas laser based on a multisectional discharge gap

    SciTech Connect

    Lazhintsev, B V; Nor-Arevyan, V A

    2000-01-31

    An electric discharge laser with an electrode unit of novel design was developed. An electric discharge system was based on multisectional plate-like electrodes and an automatic UV preionisation that makes it possible to form a highly stable volume discharge. High-efficiency lasing in N{sub 2} and XeF lasers was achieved. A pulse repetition rate up to 200 Hz was realised in the N{sub 2} laser without recourse to gas circulation. (lasers)

  20. Atomic iodine production in a gas flow by decomposing methyl iodide in a dc glow discharge

    SciTech Connect

    Mikheyev, P A; Shepelenko, A A; Voronov, A I; Kupryaev, Nikolai V

    2002-01-31

    The production of atomic iodine for an oxygen - iodine laser is studied by decomposing methyl iodide in a dc glow discharge in a vortex gas flow. The concentration of iodine atoms in discharge products was measured from the atomic iodine absorption of the radiation of a single-frequency tunable diode laser at a wavelength of 1.315 {mu}m. Atomic iodine concentrations sufficient for the operation of an oxygen - iodine laser were obtained. The concentration of atomic iodine amounted to 3.6 x 10{sup 15} cm{sup -3} for a pressure of the carrying argon gas of 15 Torr. The discharge stabilisation by a vortex gas flow allowed the glow discharge to be sustained in a strongly electronegative halogen-containing gas mixture for pressures up to 20 Torr. (active media)

  1. Atmospheric pressure helium afterglow discharge detector for gas chromatography

    DOEpatents

    Rice, Gary; D'Silva, Arthur P.; Fassel, Velmer A.

    1986-05-06

    An apparatus for providing a simple, low-frequency electrodeless discharge system for atmospheric pressure afterglow generation. A single quartz tube through which a gas mixture is passed is extended beyond a concentric electrode positioned thereabout. A grounding rod is placed directly above the tube outlet to permit optical viewing of the discharge between the electrodes.

  2. Atmospheric pressure helium afterglow discharge detector for gas chromatography

    DOEpatents

    Rice, G.; D'Silva, A.P.; Fassel, V.A.

    1985-04-05

    An apparatus for providing a simple, low-frequency, electrodeless discharge system for atmospheric pressure afterglow generation. A single quartz tube through which a gas mixture is passed is extended beyond a concentric electrode positioned thereabout. A grounding rod is placed directly above the tube outlet to permit optical viewing of the discharge between the electrodes.

  3. Gas lasers pumped by runaway electrons preionized diffuse discharge

    NASA Astrophysics Data System (ADS)

    Panchenko, Alexei N.; Lomaev, Mikhail I.; Panchenko, Nikolai A.; Tarasenko, Victor F.; Suslov, Alexei I.

    2015-05-01

    It was shown that run-away electron preionized volume (diffuse) discharge (REP DD) can be used as an excitation source of gas mixtures at elevated pressures and can produce laser emission. We report experimental and simulated results of application of the REP DD for excitation of different active gas mixtures. Kinetic model of the REP DD in mixtures of nitrogen with SF6 is developed allowing predicting the radiation parameters of nitrogen laser at 337.1 nm. Peculiarities of the REP DD development in different gas mixtures are studied, as well. It was shown that the REP DD allows obtaining efficient lasing stimulated radiation in the IR, visible and UV spectral ranges. New operation mode of nitrogen laser is demonstrated under REP DD excitation. Laser action on N2, HF, and DF molecules was obtained with the efficiency close to the limiting value. Promising prospects of REP DD employment for exciting a series of gas lasers was demonstrated. It was established that the REP DD is most efficient for pumping lasers with the mixtures comprising electro-negative gases.

  4. Advances in electron kinetics and theory of gas discharges

    SciTech Connect

    Kolobov, Vladimir I.

    2013-10-15

    “Electrons, like people, are fertile and infertile: high-energy electrons are fertile and able to reproduce.”—Lev TsendinModern physics of gas discharges increasingly uses physical kinetics for analysis of non-equilibrium plasmas. The description of underlying physics at the kinetic level appears to be important for plasma applications in modern technologies. In this paper, we attempt to grasp the legacy of Professor Lev Tsendin, who advocated the use of the kinetic approach for understanding fundamental problems of gas discharges. We outline the fundamentals of electron kinetics in low-temperature plasmas, describe elements of the modern kinetic theory of gas discharges, and show examples of the theoretical approach to gas discharge problems used by Lev Tsendin. Important connections between electron kinetics in gas discharges and semiconductors are also discussed. Using several examples, we illustrate how Tsendin's ideas and methods are currently being developed for the implementation of next generation computational tools for adaptive kinetic-fluid simulations of gas discharges used in modern technologies.

  5. Re-examination of demonstration gas discharge tubes

    SciTech Connect

    Maharaj, H.P. )

    1991-10-01

    Gas discharge tubes in which electrons or ions are accelerated at voltages on the order of kilovolts to produce observable atomic effects are potential x-ray sources. These tubes come in various shapes, sizes and designs, and are still in use in science classrooms despite the decline predicted in the 1970s. Because of current applications, a representative sample consisting of fifteen tubes marketed over a recent 2-year period was reexamined for regulatory compliance, product identification and advertising. The results revealed that: poor quality control and design can affect x-ray emissions; and deficiencies exist in product identification, safe use guidelines and operating instructions. This paper reports that these findings, together with the dose estimates, implications and subjective indicators, strongly suggest a user group of unknown size is at increased risk. A combination of enhanced surveillance and promotion of user awareness strategies is adopted to reduce and possible eliminate the potential health risks.

  6. Temporally, spatially, and spectrally resolved barrier discharge produced in trapped helium gas at atmospheric pressure

    SciTech Connect

    Chiper, Alina Silvia; Popa, Gheorghe

    2013-06-07

    Experimental study was made on induced effects by trapped helium gas in the pulsed positive dielectric barrier discharge (DBD) operating in symmetrical electrode configuration at atmospheric pressure. Using fast photography technique and electrical measurements, the differences in the discharge regimes between the stationary and the flowing helium are investigated. It was shown experimentally that the trapped gas atmosphere (TGA) has notable impact on the barrier discharge regime compared with the influence of the flowing gas atmosphere. According to our experimental results, the DBD discharge produced in trapped helium gas can be categorized as a multi-glow (pseudo-glow) discharge, each discharge working in the sub-normal glow regime. This conclusion is made by considering the duration of current pulse (few {mu}s), their maximum values (tens of mA), the presence of negative slope on the voltage-current characteristic, and the spatio-temporal evolution of the most representative excited species in the discharge gap. The paper focuses on the space-time distribution of the active species with a view to better understand the pseudo-glow discharge mechanism. The physical basis for these effects was suggested. A transition to filamentary discharge is suppressed in TGA mode due to the formation of supplementary source of seed electrons by surface processes (by desorption of electrons due to vibrationally excited nitrogen molecules, originated from barriers surfaces) rather than volume processes (by enhanced Penning ionisation). Finally, we show that the pseudo-glow discharge can be generated by working gas trapping only; maintaining unchanged all the electrical and constructive parameters.

  7. Plasma physics issues in gas discharge laser development

    SciTech Connect

    Garscadden, A. ); Kushner, M.J.; Eden, J.G. . Dept. of Electrical and Computer Engineering)

    1991-12-01

    In this paper an account is given of the interplay between partially ionized plasma physics and the development of gas discharge lasers. Gas discharge excitation has provided a wide array of laser devices extending from the soft X-ray region to the far infrared. The scaling of gas discharge lasers in power and energy also covers many orders of magnitude. The particular features of three regimes are discussed: short wavelength lasers (deep UV to soft X-ray); visible and near UV lasers; and infrared molecular gas lasers. The current status (Fall 1990) of these areas is reviewed, and an assessment is made of future research topics that are perceived to be important.

  8. Governmental oversight of discharges from concentrated animal feeding operations.

    PubMed

    Centner, Terence J

    2006-06-01

    As point sources of pollution in the United States, concentrated animal feeding operations (CAFOs) are subject to the National Pollution Discharge Elimination System permitting system requirements. Changes to federal regulations in 2003 and a 2005 court decision have increased the governmental oversight of CAFOs. Manure application to fields from "large CAFOs" that results in unpermitted discharges can be regulated under the Clean Water Act. The U.S. Environmental Protection Agency's interpretation of agricultural stormwater discharges was approved so that unpermitted discharges may arise if an owner or operator of a CAFO fails to apply manure correctly. Owners and operators do not, however, have a duty to secure governmental permits in the absence of a discharge. Turning to the federal provisions regarding nutrient management plans, a court found that they were deficient. Moreover, the federal government needs to reconsider requirements that would reduce pathogens from entering surface waters. Although these developments should assist in reducing the impairment of U.S. waters, concern still exists. Greater oversight of nutrient management plans and enhanced enforcement efforts offer opportunities to provide greater assurance that CAFO owners and operators will not allow a discharge of pollutants to enter surface waters. PMID:16456627

  9. Gas mixture for diffuse-discharge switch

    DOEpatents

    Christophorou, Loucas G.; Carter, James G.; Hunter, Scott R.

    1984-01-01

    Gaseous medium in a diffuse-discharge switch of a high-energy pulse generator is formed of argon combined with a compound selected from the group consisting of CF.sub.4, C.sub.2 F.sub.6, C.sub.3 F.sub.8, n-C.sub.4 F.sub.10, WF.sub.6, (CF.sub.3).sub.2 S and (CF.sub.3).sub.2 O.

  10. Gas mixture for diffuse-discharge switch

    DOEpatents

    Christophorou, L.G.; Carter, J.G.; Hunter, S.R.

    1982-08-31

    Gaseous medium in a diffuse-discharge switch of a high-energy pulse generator is formed of argon combined with a compound selected from the group consisting of CF/sub 4/, C/sub 2/F/sub 6/, C/sub 3/F/sub 8/, n-C/sub 4/F/sub 10/, WF/sub 6/, (CF/sub 3/)/sub 2/S and (CF/sub 3/)/sub 2/O.

  11. Broad beam gas ion source with hollow cathode discharge and four-grid accelerator system

    NASA Astrophysics Data System (ADS)

    Tang, Deli; Pu, Shihao; Huang, Qi; Tong, Honghui; Cui, Xirong; Chu, Paul K.

    2007-04-01

    A broad beam gas ion source based on low-pressure hollow cathode glow discharge is described. An axial magnetic filed produced by AlNiCo permanent magnets enhances the glow discharge in the ion source as a result of the magnetizing electrons between the hollow cathode and rod anode. The gas plasma is produced by magnetron hollow cathode glow discharge in the hollow cathode and a collimated broad ion beam is extracted by a four-grid accelerator system. A weak magnetic field of several millitesla is enough to ignite the magnetron glow discharge at pressure lower than 0.1 Pa, thereby enabling stable and continuous high-current discharge to form the homogeneous plasma. A four-grid accelerator, which separates the extraction and acceleration of the ion beam, is used in this design to generate the high-energy ion beam from 10 keV to 60 keV at a working pressure of 10-4 Torr. Although a higher gas pressure is necessary to maintain the low-pressure glow discharge when compared to hot filament discharge, the hollow cathode ion source is operational with reactive gases such as oxygen in the high-voltage continuous mode. A laterally uniform ion beam can be achieved by using the four-grid accelerator system. The effects of the rod anode length on the characteristics of the plasma discharge as well as ion beam extraction from the ion source are discussed.

  12. Periodically Discharging, Gas-Coalescing Filter

    NASA Technical Reports Server (NTRS)

    Carter, Donald Layne; Holder, Donald W.

    2006-01-01

    A proposed device would remove bubbles of gas from a stream of liquid (typically water), accumulate the gas, and periodically release the gas, in bulk, back into the stream. The device is intended for use in a flow system (1) in which there is a requirement to supply bubble-free water to a downstream subsystem and (2) that includes a sensor and valves, just upstream of the subsystem, for sensing bubbles and diverting the flow from the subsystem until the water stream is again free of bubbles. By coalescing the gas bubbles and then periodically releasing the accumulated gas, the proposed device would not contribute to net removal of gas from the liquid stream; nevertheless, it would afford an advantage by reducing the frequency with which the diverter valves would have to be activated. The device (see figure) would include an upper and a lower porous membrane made of a hydrophilic material. Both membranes would cover openings in a tube leading to an outlet. These membranes would allow water, but not gas bubbles, to pass through to the interior of the tube. Inside the tube, between the two membranes, there would be a flow restrictor that would play a role described below. Below both membranes there would be a relief valve. Water, possibly containing bubbles, would enter from the top and would pass through either the lower membrane or both membranes, depending how much gas had been accumulated thus far. When the volume of accumulated gas was sufficient to push the top surface of the liquid below the lower porous membrane, water could no longer flow through either membrane toward the outlet. This blockage would cause an increase in back pressure that would cause the relief valve to open. The opening of the relief valve would allow both the water and the bulk-accumulated gas to pass through to the outlet. Once the gas had been pushed out, water would once again flow through both membranes at a much lower pressure drop. The flow restrictor would maintain enough pressure

  13. Interaction of a surface glow discharge with a gas flow

    SciTech Connect

    Aleksandrov, A. L. Schweigert, I. V.

    2010-05-15

    A surface glow discharge in a gas flow is of particular interest as a possible tool for controlling the flow past hypersonic aircrafts. Using a hydrodynamic model of glow discharge, two-dimensional calculations for a kilovolt surface discharge in nitrogen at a pressure of 0.5 Torr are carried out in a stationary gas, as well as in a flow with a velocity of 1000 m/s. The discharge structure and plasma parameters are investigated near a charged electrode. It is shown that the electron energy in a cathode layer reaches 250-300 eV. Discharge is sustained by secondary electron emission. The influence of a high-speed gas flow on the discharge is considered. It is shown that the cathode layer configuration is flow-resistant. The distributions of the electric field and electron energy, as well as the ionization rate profile in the cathode layer, do not change qualitatively under the action of the flow. The basic effect of the flow's influence is a sharp decrease in the region of the quasineutral plasma surrounding the cathode layer due to fast convective transport of ions.

  14. Pulsed microwave discharge in a capillary filled with atmospheric-pressure gas

    SciTech Connect

    Gritsinin, S. I.; Gushchin, P. A.; Davydov, A. M.; Ivanov, E. V.; Kossyi, I. A.

    2013-08-15

    A pulsed microwave coaxial capillary plasma source generating a thin plasma filament along the capillary axis in an atmospheric-pressure argon flow is described. The dynamics of filament formation is studied, and the parameters of the gas and plasma in the contraction region are determined. A physical model of discharge formation and propagation is proposed. The model is based on the assumption that, under the conditions in which the electric fields is substantially below the threshold value, the discharge operates in a specific form known as a self-sustained-non-self-sustained (SNS) microwave discharge.

  15. Features of plasma glow in low pressure terahertz gas discharge

    NASA Astrophysics Data System (ADS)

    Bratman, V. L.; Golubev, S. V.; Izotov, I. V.; Kalynov, Yu. K.; Koldanov, V. A.; Litvak, A. G.; Razin, S. V.; Sidorov, A. V.; Skalyga, V. A.; Zorin, V. G.

    2013-12-01

    Investigations of the low pressure (1-100 Torr) gas discharge in the powerful (1 kW) quasi-optical terahertz (0.55 THz) wave beams were made. An intense afterglow was observed after the end of gyrotron terahertz radiation pulse. Afterglow duration significantly exceeded radiation pulse length (8 μs). This phenomenon could be explained by the strong dependence of the collisional-radiative recombination rate (that is supposed to be the most likely mechanism of electron losses from the low pressure terahertz gas discharge) on electron temperature.

  16. Features of plasma glow in low pressure terahertz gas discharge

    SciTech Connect

    Bratman, V. L.; Golubev, S. V.; Izotov, I. V.; Kalynov, Yu. K.; Koldanov, V. A.; Razin, S. V.; Litvak, A. G.; Sidorov, A. V.; Skalyga, V. A.; Zorin, V. G.

    2013-12-15

    Investigations of the low pressure (1–100 Torr) gas discharge in the powerful (1 kW) quasi-optical terahertz (0.55 THz) wave beams were made. An intense afterglow was observed after the end of gyrotron terahertz radiation pulse. Afterglow duration significantly exceeded radiation pulse length (8 μs). This phenomenon could be explained by the strong dependence of the collisional-radiative recombination rate (that is supposed to be the most likely mechanism of electron losses from the low pressure terahertz gas discharge) on electron temperature.

  17. Method and apparatus for processing exhaust gas with corona discharge

    DOEpatents

    Barlow, Stephan E.; Orlando, Thomas M.; Tonkyn, Russell G.

    1999-01-01

    The present invention is placing a catalyst coating upon surfaces surrounding a volume containing corona discharge. In addition, the electrodes are coated with a robust dielectric material. Further, the electrodes are arranged so that at least a surface portion of each electrode extends into a flow path of the exhaust gas to be treated and there is only exhaust gas in the volume between each pair of electrodes.

  18. Method and apparatus for processing exhaust gas with corona discharge

    DOEpatents

    Barlow, S.E.; Orlando, T.M.; Tonkyn, R.G.

    1999-06-22

    The present invention is placing a catalyst coating upon surfaces surrounding a volume containing corona discharge. In addition, the electrodes are coated with a robust dielectric material. Further, the electrodes are arranged so that at least a surface portion of each electrode extends into a flow path of the exhaust gas to be treated and there is only exhaust gas in the volume between each pair of electrodes. 12 figs.

  19. Pulsed electrical discharge in gas bubbles in water

    NASA Astrophysics Data System (ADS)

    Gershman, Sophia

    A phenomenological picture of pulsed electrical discharge in gas bubbles in water is produced by combining electrical, spectroscopic, and imaging methods. The discharge is generated by applying one microsecond long 5 to 20 kilovolt pulses between the needle and disk electrodes submerged in water. A gas bubble is generated at the tip of the needle electrode. The study includes detailed experimental investigation of the discharge in argon bubbles and a brief look at the discharge in oxygen bubbles. Imaging, electrical characteristics, and time-resolved optical emission data point to a fast streamer propagation mechanism and formation of a plasma channel in the bubble. Spectroscopic methods based on line intensity ratios and Boltzmann plots of line intensities of argon, atomic hydrogen, and argon ions and the examination of molecular emission bands from molecular nitrogen and hydroxyl radicals provide evidence of both fast beam-like electrons and slow thermalized ones with temperatures of 0.6 -- 0.8 electron-volts. The collisional nature of plasma at atmospheric pressure affects the decay rates of optical emission. Spectroscopic study of rotational-vibrational bands of hydroxyl radical and molecular nitrogen gives vibrational and rotational excitation temperatures of the discharge of about 0.9 and 0.1 electron-volt, respectively. Imaging and electrical evidence show that discharge charge is deposited on the bubble wall and water serves as a dielectric barrier for the field strength and time scales of this experiment. Comparing the electrical and imaging information for consecutive pulses applied at a frequency of 1 Hz indicates that each discharge proceeds as an entirely new process with no memory of the previous discharge aside from long-lived chemical species, such as ozone and oxygen. Intermediate values for the discharge gap and pulse duration, low repetition rate, and unidirectional character of the applied voltage pulses make the discharge process here unique

  20. Direct-current converter for gas-discharge lamps

    NASA Technical Reports Server (NTRS)

    Lutus, P.

    1980-01-01

    Metal/halide and similar gas-discharge lamps are powered from low-voltage dc source using small efficient converter. Converter is useful whenever 60-cycle ac power is not available or where space and weight allocations are limited. Possible applications are offshore platforms, mobile homes, and emergency lighting. Design innovations give supply high reliability and efficiency up to 75 percent.

  1. Spots and patterns on electrodes of gas discharges

    NASA Astrophysics Data System (ADS)

    Benilov, Mikhail

    2015-09-01

    Concentration of electrical current onto the surface of electrodes of gas discharges in well-defined regions, or current spots, is often the rule rather than the exception. These spots occur on otherwise uniform electrode surfaces, a regime where one might expect a uniform distribution of current over the surface. In many cases, multiple spots may appear, forming beautiful patterns and surprising the observer. Important advances have been attained in the last 15 years in experimental investigation, understanding, and modelling of spots and patterns in discharges of different types, in particular, high-pressure arc discharges, dc glow discharges, and barrier discharges. It became clear that in many, if not most, cases there is no need to look for special physical mechanisms responsible for the formation of spots or patterns on uniform electrode surfaces: the spots or patterns originate in self-organization caused by (nonlinear) interaction of well-known mechanisms. In particular, standard mechanisms of near-cathode space-charge sheath are sufficient to produce self-organization, and it is this kind of self-organization that gives rise to cathode spots in low-current high-pressure arcs and normal spots and patterns of spots on cathodes of dc glow discharges. It was shown that spots and patterns on electrodes of gas discharges, being self-organization phenomena, are inherently related to multiple solutions, with one of the solutions describing a mode with a uniform distribution of current over the electrode surface and the others describing regimes with different spot patterns. These multiple solutions exist even in the most basic self-consistent models of gas discharges. In particular, multiple solutions have been found for dc glow discharges; the fact rather surprising by itself, given that such discharges have been under intensive theoretical investigation for many years. A concise review of the above-described advances is given in this talk. Work supported by FCT

  2. Comparison of electrical and optical characteristics in gas-phase and gas-liquid phase discharges

    SciTech Connect

    Qazi, H. I. A.; Li, He-Ping Zhang, Xiao-Fei; Bao, Cheng-Yu; Nie, Qiu-Yue

    2015-12-15

    This paper presents an AC-excited argon discharge generated using a gas-liquid (two-phase) hybrid plasma reactor, which mainly consists of a powered needle electrode enclosed in a conical quartz tube and grounded deionized water electrode. The discharges in the gas-phase, as well as in the two-phase, exhibit two discharge modes, i.e., the low current glow-like diffuse mode and the high current streamer-like constrict mode, with a mode transition, which exhibits a negative resistance of the discharges. The optical emission spectral analysis shows that the stronger diffusion of the water vapor into the discharge region in the two-phase discharges boosts up the generation of OH (A–X) radicals, and consequently, leads to a higher rotational temperature in the water-phase plasma plume than that of the gas-phase discharges. Both the increase of the power input and the decrease of the argon flow rate result in the increase of the rotational temperature in the plasma plume of the water-phase discharge. The stable two-phase discharges with a long plasma plume in the water-phase under a low power input and gas flow rate may show a promising prospect for the degradation of organic pollutants, e.g., printing and dyeing wastewater, in the field of environmental protection.

  3. Comparison of electrical and optical characteristics in gas-phase and gas-liquid phase discharges

    NASA Astrophysics Data System (ADS)

    Qazi, H. I. A.; Nie, Qiu-Yue; Li, He-Ping; Zhang, Xiao-Fei; Bao, Cheng-Yu

    2015-12-01

    This paper presents an AC-excited argon discharge generated using a gas-liquid (two-phase) hybrid plasma reactor, which mainly consists of a powered needle electrode enclosed in a conical quartz tube and grounded deionized water electrode. The discharges in the gas-phase, as well as in the two-phase, exhibit two discharge modes, i.e., the low current glow-like diffuse mode and the high current streamer-like constrict mode, with a mode transition, which exhibits a negative resistance of the discharges. The optical emission spectral analysis shows that the stronger diffusion of the water vapor into the discharge region in the two-phase discharges boosts up the generation of OH (A-X) radicals, and consequently, leads to a higher rotational temperature in the water-phase plasma plume than that of the gas-phase discharges. Both the increase of the power input and the decrease of the argon flow rate result in the increase of the rotational temperature in the plasma plume of the water-phase discharge. The stable two-phase discharges with a long plasma plume in the water-phase under a low power input and gas flow rate may show a promising prospect for the degradation of organic pollutants, e.g., printing and dyeing wastewater, in the field of environmental protection.

  4. Gas laser in which the gas is excited by capacitor discharge

    SciTech Connect

    Lacour, B.; de Witte, O.; Maillet, M.; Vannier, C.

    1985-01-22

    A gas laser in which the gas is excited by laser discharge, said laser including two capacitors formed by two parallel metal plates between which two dielectric parts are spaced apart to form a passage which contains the laser gas. It further includes a transformer whose secondary winding is connected to the plates and whose primary winding is connected in series with a capacitor, means for charging and capacitor and a thyristor for discharging the capacitor in the primary winding. Application to exciting gas lasers in which the gas contains a dye stuff.

  5. Control of stochastic sensitivity in a stabilization problem for gas discharge system

    SciTech Connect

    Bashkirtseva, Irina

    2015-11-30

    We consider a nonlinear dynamic stochastic system with control. A problem of stochastic sensitivity synthesis of the equilibrium is studied. A mathematical technique of the solution of this problem is discussed. This technique is applied to the problem of the stabilization of the operating mode for the stochastic gas discharge system. We construct a feedback regulator that reduces the stochastic sensitivity of the equilibrium, suppresses large-amplitude oscillations, and provides a proper operation of this engineering device.

  6. The gas conversion of methane with oxygen at atmospheric pressure using a cylindrical dielectric barrier discharge

    NASA Astrophysics Data System (ADS)

    Martens, Tom; Petrovic, Dragana; de Bie, Christophe; Bogaerts, Annemie; Brok, Wouter; van Dijk, Jan

    2008-10-01

    The conversion of methane to useful chemicals and liquid fuels currently requires steam reforming, which requires great amounts of energy input. We are currently investigating the possibilities of using a plasma activated system for this gas conversion. Due to the pulsed nature and the low operating temperature capabilities, we have chosen the atmospheric pressure dielectric barrier discharge as a setup to investigate whether it can be used as a more efficient gas conversion reactor. For this purpose we have developed a CH4/O2 chemical reaction set and used it in a 2D fluid model of a cylindrical dielectric barrier discharge, in which we also incorporate the influence of the gas flow. In this way we investigate whether we can optimize the production of methanol or formaldehyde. The parameters under study are the CH4/O2 ratio, the applied voltage characteristics, the gap width and the gas flow rate.

  7. Exploration of the Townsend regime by discharge light emission in a gas discharge device

    NASA Astrophysics Data System (ADS)

    Hilal Yucel, Kurt

    2014-01-01

    The Townsend discharge mechanism has been explored in a planar microelectronic gas discharge device (MGDD) with different applied voltages U and interelectrode distance d under various pressures in air. The anode and the cathode of the MGDD are formed by a transparent SnO2 covered glass and a GaAs semiconductor, respectively. In the experiments, the discharge is found to be unstable just below the breakdown voltage Ub, whereas the discharge passes through a homogeneous stable Townsend mode beyond the breakdown voltage. The measurements are made by an electrical circuit and a CCD camera by recording the currents and light emission (LE) intensities. The intensity profiles, which are converted from the 3D light emission images along the semiconductor diameter, have been analysed for different system parameters. Different instantaneous conductivity σt regimes are found below and beyond the Townsend region. These regimes govern the current and spatio-temporal LE stabilities in the plasma system. It has been proven that the stable LE region increases up to 550 Torr as a function of pressure for small d. If the active area of the semiconductor becomes larger and the interlectrode distance d becomes smaller, the stable LE region stays nearly constant with pressure.

  8. Decomposition of dimethylamine gas with dielectric barrier discharge.

    PubMed

    Ye, Zhaolian; Zhao, Jie; Huang, Hong ying; Ma, Fei; Zhang, Renxi

    2013-09-15

    The decomposition of dimethylamine (DMA) with gas under high flow rate was investigated with dielectric barrier discharge (DBD) technology. Different parameters including removal efficiency, energy yield, carbon balance and CO2 selectivity, secondary products, as well as pathways and mechanisms of DMA degradation were studied. The experimental results showed that removal efficiency of DMA depended on applied voltage and gas flow rate, but had no obvious correlation with initial concentration. Excellent energy performance was obtained using present DBD technology for DMA abatement. When experiment conditions were controlled at: gas flow rate of 14.9 m(3)/h, initial concentration of 2104 mg/m(3), applied voltage of 4.8 kV, removal efficiency of DMA and energy yield can reach 85.2% and 953.9 g/kWh, respectively. However, carbon balance (around 40%) was not ideal due to shorter residence time (about 0.1s), implying that some additional conditions should be considered to improve the total oxidation of DMA. Moreover, secondary products in outlet gas stream were detected via gas chromatogram-mass spectrum and the amounts of NO3(-) and NO2(-) were analyzed by ion chromatogram. The obtained data demonstrated that NOx might be suppressed due to reductive NH radical form DMA dissociation. The likely reaction pathways and mechanisms for the removal of DMA were suggested based on products analysis. Experimental results demonstrated the application potential of DBD as a clean technology for organic nitrogen-containing gas elimination from gas streams. PMID:23742954

  9. Gas-discharge improving ecological characteristics of the atmosphere

    NASA Astrophysics Data System (ADS)

    Batanov, German; Kossyi, Igor; Silakov, Valerii

    2004-09-01

    GAS-DISCHARGE IMPROVING ECOLOGICALCHARACTERISTICS OF THE ATMOSPHERE 2.20. Environmental applications G.M.Batanov, I.A.Kossyi and V.P.Silakov Prokhorov Institute of General Physics, Russian Academy of Sciences, Vavilov Street 38, 119991, Moscow, Russia The possibility of improving ecological characteristics of the atmosphere with the help of freely localized microwave discharge is analyzed. Theoretical and experimental studies devoted to cleaning the troposphere of ozone-destroying pollutants and creating an artificial ozone layer in the stratosphere are reviewed. Experiments performed with convergent powerful microwave beam exciting discharge in condition close to the natural atmosphere one are discussed. Theoretical consideration of consequences of freely localized microwave discharge in atmosphere are analyzed and conclusions concerning to the possibility to improve ecological situation are made. Results of the studies in the Institute of General Physics of the possibility of the plasmachemical utilization of the accumulated chlorofluorocarbons (CFCs), capable of depleting the ozone layer, are presented. Experiments open up new avenues for development of an efficient reactor dedicated to the "harmful" CFCs decomposition. The results of theoretical and experimental modeling are used to predict the plasmachemical consequences of creating artificial ionized regions in the upper atmosphere for the purpose of long-range radio and TV communications.

  10. Gas flow dependence of atmospheric pressure plasma needle discharge characteristics

    NASA Astrophysics Data System (ADS)

    Qian, Muyang; Yang, Congying; Liu, Sanqiu; Chen, Xiaochang; Ni, Gengsong; Wang, Dezhen

    2016-04-01

    In this paper, a two-dimensional coupled model of neutral gas flow and plasma dynamics is presented to explain the gas flow dependence of discharge characteristics in helium plasma needle at atmospherics pressure. The diffusional mixing layer between the helium jet core and the ambient air has a moderate effect on the streamer propagation. The obtained simulation results present that the streamer shows the ring-shaped emission profile at a moderate gas flow rate. The key chemical reactions which drive the streamer propagation are electron-impact ionization of helium neutral, nitrogen and oxygen molecules. At a moderate gas flow rate of 0.5 slm, a significant increase in propagation velocity of the streamer is observed due to appropriate quantity of impurities air diffuse into the helium. Besides, when the gas flow rate is below 0.35 slm, the radial density of ground-state atomic oxygen peaks along the axis of symmetry. However, when the gas flow rate is above 0.5 slm, a ring-shaped density distribution appears. The peak density is on the order of 1020 m-3 at 10 ns in our work.

  11. Two-stage plasma gun based on a gas discharge with a self-heating hollow emitter.

    PubMed

    Vizir, A V; Tyunkov, A V; Shandrikov, M V; Oks, E M

    2010-02-01

    The paper presents the results of tests of a new compact two-stage bulk gas plasma gun. The plasma gun is based on a nonself-sustained gas discharge with an electron emitter based on a discharge with a self-heating hollow cathode. The operating characteristics of the plasma gun are investigated. The discharge system makes it possible to produce uniform and stable gas plasma in the dc mode with a plasma density up to 3x10(9) cm(-3) at an operating gas pressure in the vacuum chamber of less than 2x10(-2) Pa. The device features high power efficiency, design simplicity, and compactness. PMID:20192469

  12. Gas-discharge plasma sources for nonlocal plasma technology

    SciTech Connect

    Demidov, V. I.; DeJoseph, C. A. Jr.; Simonov, V. Ya.

    2007-11-12

    Nonlocal plasma technology is based on the effect of self-trapping of fast electrons in the plasma volume [V. I. Demidov, C. A. DeJoseph, Jr., and A. A. Kudryavtsev, Phys. Rev. Lett. 95, 215002 (2006)]. This effect can be achieved by changing the ratio of fast electron flux to ion flux incident on the plasma boundaries. This in turn leads to a significant change in plasma properties and therefore can be useful for technological applications. A gas-discharge device which demonstrates control of the plasma properties by this method is described.

  13. Piezoelectric transformers for low-voltage generation of gas discharges and ionic winds in atmospheric air

    SciTech Connect

    Johnson, Michael J.; Go, David B.

    2015-12-28

    To generate a gas discharge (plasma) in atmospheric air requires an electric field that exceeds the breakdown threshold of ∼30 kV/cm. Because of safety, size, or cost constraints, the large applied voltages required to generate such fields are often prohibitive for portable applications. In this work, piezoelectric transformers are used to amplify a low input applied voltage (<30 V) to generate breakdown in air without the need for conventional high-voltage electrical equipment. Piezoelectric transformers (PTs) use their inherent electromechanical resonance to produce a voltage amplification, such that the surface of the piezoelectric exhibits a large surface voltage that can generate corona-like discharges on its corners or on adjacent electrodes. In the proper configuration, these discharges can be used to generate a bulk air flow called an ionic wind. In this work, PT-driven discharges are characterized by measuring the discharge current and the velocity of the induced ionic wind with ionic winds generated using input voltages as low as 7 V. The characteristics of the discharge change as the input voltage increases; this modifies the resonance of the system and subsequent required operating parameters.

  14. Piezoelectric transformers for low-voltage generation of gas discharges and ionic winds in atmospheric air

    NASA Astrophysics Data System (ADS)

    Johnson, Michael J.; Go, David B.

    2015-12-01

    To generate a gas discharge (plasma) in atmospheric air requires an electric field that exceeds the breakdown threshold of ˜30 kV/cm. Because of safety, size, or cost constraints, the large applied voltages required to generate such fields are often prohibitive for portable applications. In this work, piezoelectric transformers are used to amplify a low input applied voltage (<30 V) to generate breakdown in air without the need for conventional high-voltage electrical equipment. Piezoelectric transformers (PTs) use their inherent electromechanical resonance to produce a voltage amplification, such that the surface of the piezoelectric exhibits a large surface voltage that can generate corona-like discharges on its corners or on adjacent electrodes. In the proper configuration, these discharges can be used to generate a bulk air flow called an ionic wind. In this work, PT-driven discharges are characterized by measuring the discharge current and the velocity of the induced ionic wind with ionic winds generated using input voltages as low as 7 V. The characteristics of the discharge change as the input voltage increases; this modifies the resonance of the system and subsequent required operating parameters.

  15. Dynamic processes in active medium of small diameter gas discharge lasers

    NASA Astrophysics Data System (ADS)

    Schishov, S. I.

    2008-03-01

    Review of electrodynamics properties for gas discharge lasers of small diameter has been completed with consideration of inertia typical for ionisation processes and transient nature of electron diffusion from unipolar to ambipolar. Procedure for calculation of transfer function and elements of equivalent electrical circuit for substitution of gas discharge laser discharge space.

  16. Experimental investigation on the effect of plasma jet in the triggered discharge process of a gas switch

    NASA Astrophysics Data System (ADS)

    Tie, W.; Liu, S.; Liu, X.; Zhang, Q.

    2016-08-01

    The temporal and spatial evolution of a plasma jet generated by a spark discharge was observed. The electron temperature and density were obtained under different time and gas pressures by optical emission spectroscopy. Moreover, the discharge process of the plasma-jet triggered gas switch was recorded and analyzed at the lowest working coefficient. The results showed that the plasma jet moved forward in a bullet mode, and the advancing velocity increased with the decrease of pressure, and decreased with time growing. At initial time, the maximum velocity of a plasma jet could reach 3.68 × 106 cm/s. The electron temperature decreased from 2.0 eV to 1.3 eV, and the electron density increased from 3.1 × 1015/cm3 to 6.3 × 1015/cm3 at the initial moment as the gas pressure increases from 0.1 MPa to 0.32 MPa. For a two-gap gas switch, the discharge performances were more depended on the second discharge spark gap (gap 2). Because plasma jet promoted the discharge in Gap 2, the gas switch operating in mode II had better triggered discharge characteristics. In the discharge process, the plasma-jet triggering had the effect of non-penetrating inducing, which not only provided initial electrons for reducing statistical lag but also enhanced the local electric field. The discharge was initiated and accelerated from electron avalanche to streamer. Therefore, a fast discharge was occurred in the gas switch.

  17. Dynamic Reduction Effect of CO2 Gas Discharge in Introducing Electric Vehicles

    NASA Astrophysics Data System (ADS)

    Liu, Bin; Inaba, Tsuginori

    For this study, the dynamic reduction effect of CO2 gas discharge for change from internal combustion engines to electric vehicles, EVs, was investigated quantitatively. The Japanese power generation status, which shows characteristics of electricity generation, and optimized adjustment to electricity demand, load and environment was examined. Based on a CO2 gas discharge basic unit, the estimated reduction quantity of CO2 gas discharge from EVs was calculated. The reduction effect of CO2 gas discharge is expected to be 52% by changing gas-fuelled vehicles to EVs. However, the dynamic differential is only 19% reduction by using the thermal power and -2% if only the coal thermal power is used.

  18. Self-Organization and Migration of Dielectric Barrier Discharge Filaments in Argon Gas Flow

    PubMed Central

    Yang, Yong; Cho, Young I.; Friedman, Gary; Fridman, Alexander; Fridman, Greg

    2012-01-01

    Observations of atmospheric-pressure dielectric barrier discharge are conducted through a water-filled electrode in atmospheric-pressure argon gas flow. Quasi-symmetric self-organized discharge filaments were observed. The streamers moved with the gas flow, and the migration velocity increased with increasing gas velocity. PMID:22287814

  19. The oil and gas joint operating agreement

    SciTech Connect

    Not Available

    1990-01-01

    This book covers the following topics: introduction to the AAPL model form operating agreement; property provisions of the operating agreement; Article 6---the drilling and development article; duties and obligations revisited---who bear what risk of loss; operator's liens; accounting procedure joint operations; insurance; taking gas in kind absent a balancing agreement; RMMLF Form 5 Gas Balancing Agreement; tax partnerships for nontax professionals; alternative agreement forms.

  20. High-power gas-discharge excimer ArF, KrCl, KrF and XeCl lasers utilising two-component gas mixtures without a buffer gas

    NASA Astrophysics Data System (ADS)

    Razhev, A. M.; Kargapol'tsev, E. S.; Churkin, D. S.

    2016-03-01

    Results of an experimental study of the influence of a gas mixture (laser active medium) composition on an output energy and total efficiency of gas-discharge excimer lasers on ArF* (193 nm), KrCl* (222 nm), KrF* (248 nm) and XeCl* (308 nm) molecules operating without a buffer gas are presented. The optimal ratios of gas components (from the viewpoint of a maximum output energy) of an active medium are found, which provide an efficient operation of laser sources. It is experimentally confirmed that for gas-discharge excimer lasers on halogenides of inert gases the presence of a buffer gas in an active medium is not a necessary condition for efficient operation. For the first time, in two-component gas mixtures of repetitively pulsed gas-discharge excimer lasers on electron transitions of excimer molecules ArF*, KrCl*, KrF* and XeCl*, the pulsed energy of laser radiation obtained under pumping by a transverse volume electric discharge in a low-pressure gas mixture without a buffer gas reached up to 170 mJ and a high pulsed output power (of up to 24 MW) was obtained at a FWHM duration of the KrF-laser pulse of 7 ns. The maximal total efficiency obtained in the experiment with two-component gas mixtures of KrF and XeCl lasers was 0.8%.

  1. Simulation of discharge in insulating gas from initial partial discharge to growth of a stepped leader using the percolation model

    NASA Astrophysics Data System (ADS)

    Sasaki, Akira; Kato, Susumu; Takahashii, Eiichi; Kishimoto, Yasuaki; Fujii, Takashi; Kanazawa, Seiji

    2016-02-01

    We show a cell simulation of a discharge in an insulating gas from the initial partial discharge to leader inception until breakdown, based on the percolation model. In the model, we consider that the propagation of the leader occurs when connections between randomly produced ionized regions in the discharge medium are established. To determine the distribution of ionized regions, the state of each simulation cell is decided by evaluating the probability of ionization in SF6, which depends on the local electric field. The electric field as well as the discharge current are calculated by solving circuit equations for the network of simulation cells. Both calculations are coupled to each other and the temporal evolution of discharge is self-consistently calculated. The model dependence of the features of the discharge is investigated. It is found that taking the suppression of attachment in the presence of a discharge current into account, the calculation reproduces the behavior of experimental discharges. It is shown that for a strong electric field, the inception of a stepped leader causes immediate breakdown. For an electric field of 30-50% of the critical field, the initial partial discharge persists for a stochastic time lag and then the propagation of a leader takes place. As the strength of the electric field decreases, the time lag increases rapidly and eventually only a partial discharge with a short arrested leader occurs, as observed in experiments.

  2. Effect of pulsed corona discharge voltage and feed gas flow rate on dissolved ozone concentration

    NASA Astrophysics Data System (ADS)

    Prasetyaningrum, A.; Ratnawati, Jos, B.

    2015-12-01

    Ozonization is one of the methods extensively used for water purification and degradation of organic materials. Ozone (O3) is recognized as a powerful oxidizing agent. Due to its strong oxidability and better environmental friendless, ozone increasing being used in domestic and industrial applications. Current technology in ozone production utilizes several techniques (corona discharge, ultra violet radiation and electrolysis). This experiment aimed to evaluating effect of voltage and gas flow rate on ozone production with corona discharge. The system consists of two net-type stainless steel electrode placed in a dielectric barrier. Three pulsed voltage (20, 30, 40 KV) and flow rate (5, 10, 15 L/min) were prepare for operation variable at high frequency (3.7 kHz) with AC pulsed power supply. The dissolved ozone concentration depends on the applied high-voltage level, gas flow rate and the discharge exposure duration. The ozone concentration increases with decreasing gas flow rate. Dissolved ozone concentrations greater than 200 ppm can be obtained with a minimum voltage 40 kV.

  3. Effect of pulsed corona discharge voltage and feed gas flow rate on dissolved ozone concentration

    SciTech Connect

    Prasetyaningrum, A. Ratnawati,; Jos, B.

    2015-12-29

    Ozonization is one of the methods extensively used for water purification and degradation of organic materials. Ozone (O{sub 3}) is recognized as a powerful oxidizing agent. Due to its strong oxidability and better environmental friendless, ozone increasing being used in domestic and industrial applications. Current technology in ozone production utilizes several techniques (corona discharge, ultra violet radiation and electrolysis). This experiment aimed to evaluating effect of voltage and gas flow rate on ozone production with corona discharge. The system consists of two net-type stainless steel electrode placed in a dielectric barrier. Three pulsed voltage (20, 30, 40 KV) and flow rate (5, 10, 15 L/min) were prepare for operation variable at high frequency (3.7 kHz) with AC pulsed power supply. The dissolved ozone concentration depends on the applied high-voltage level, gas flow rate and the discharge exposure duration. The ozone concentration increases with decreasing gas flow rate. Dissolved ozone concentrations greater than 200 ppm can be obtained with a minimum voltage 40 kV.

  4. Generation and Control of Electrolyte Cathode Atmospheric Glow Discharges using Miniature Gas Flow

    NASA Astrophysics Data System (ADS)

    Shirai, Naoki; Nakazawa, Masato; Ibuka, Shinji; Ishii, Shozo

    Stable electrolyte cathode atmospheric dc glow microdischarges were generated by using a miniature helium gas flow from a nozzle electrode in air. We developed two schemes to control the temporal evolution of the discharge and the interaction between the discharge column and the ambient air. The vaporization of electrolyte solutions takes place and affects the discharge characteristics. It takes time from the start of the discharge. Therefore the discharge was controlled by applying pulse modulated dc voltages. If the voltage was dropped down to zero before the vaporization, the gas discharge developed without the ionization of the components of solution. The helium gas discharge without air developed when the nozzle electrode was placed in a glass capillary. This was confirmed by examining the change in pH of the solution, which usually decreased owing to the generation of nitrogen oxides in the discharge in air.

  5. Coupling discharge and gas dynamics in streamer-less spark formation in supercritical N2

    NASA Astrophysics Data System (ADS)

    Agnihotri, Ashutosh; Hundsdorfer, Willem; Ebert, Ute

    2016-07-01

    A two-dimensional cylindrically symmetric model is developed to study the streamer-less spark formation in a short gap on the timescale of ion motion. It incorporates the coupling between the electric discharge and the gas through the heat generated by the discharge and the consecutive gas expansion. The model is employed to study electrical breakdown in supercritical N2. We present the simulation results of gas heating by the electrical discharge and the effect of gas expansion on the electrical discharge.

  6. Ionization front in a high-current gas discharge

    NASA Astrophysics Data System (ADS)

    Choueiri, Edgar Y.; Randolph, Thomas M.

    2007-02-01

    Spectroscopic measurements of ion/neutral density ratio profiles are made inside the high-current, low-pressure discharge of a coaxial magnetoplasmadynamic thruster and show the existence of a thin ionization front, upstream in the discharge, that effectively ionizes the incoming gas to ionization levels above 50%. The measurements allow an estimate of the width of this ionization front to be on the order of a few millimeters. Due to the known existence of microturbulence in the plasma, which can produce suprathermal electrons, an explanation of the measurements based on the existence of a suprathermal tail in the electron energy distribution function is sought. A theoretical model for the width of the ionization front is combined with a multilevel excitation model for argon and shows that a Maxwellian electron distribution function cannot account for the small length scale of the ionization front, and that the latter is more consistent with an electron distribution function having a suprathermal population, the magnitude of which is estimated by comparing the model to the experiments.

  7. Ionization front in a high-current gas discharge

    SciTech Connect

    Choueiri, Edgar Y.; Randolph, Thomas M.

    2007-03-15

    Spectroscopic measurements of ion/neutral density ratio profiles are made inside the high-current, low-pressure discharge of a coaxial magnetoplasmadynamic thruster and show the existence of a thin ionization front, upstream in the discharge, that effectively ionizes the incoming gas to ionization levels above 50%. The measurements allow an estimate of the width of this ionization front to be on the order of a few millimeters. Due to the known existence of microturbulence in the plasma, which can produce suprathermal electrons, an explanation of the measurements based on the existence of a suprathermal tail in the electron energy distribution function is sought. A theoretical model for the width of the ionization front is combined with a multilevel excitation model for argon and shows that a Maxwellian electron distribution function cannot account for the small length scale of the ionization front, and that the latter is more consistent with an electron distribution function having a suprathermal population, the magnitude of which is estimated by comparing the model to the experiments.

  8. Instability of dusty particle system in gas-discharge plasma

    SciTech Connect

    Filinov, V.S.; Petrov, O.F.; Fortov, V.E.; Molotkov, V.I.

    2005-10-31

    An effective anisotropic potential is proposed for the interaction between dust particles in a gas-discharge plasma. In addition to the Coulomb repulsion this potential takes into account attraction due to the spatial positive plasma charge originating from focusing of the ionic fluxes by dusty particles. The time evolution of the dust particle kinetic and potential energies from random initial configurations have been investigated by the Brownian dynamics method. Results of our simulation showed that the attraction between dusty particles can be the main physical reason of formation and decay of classical bound dust particle pairs and many particle complexes with low potential energy, while the kinetic energy (temperature) of unbound dust particles and particle oscillating in bound complexes may increase on three order as observed in experiments.

  9. Simulation of Gas Mixtures in RF Discharges for Nitride Deposition

    NASA Technical Reports Server (NTRS)

    Hwang, Helen H.; Meyyappan, Meyya; Arnold, James O. (Technical Monitor)

    1997-01-01

    Tungsten and titanium nitride films have long been grown by chemical vapor deposition (CVD) methods. However, there has been recent interest in low temperature growth using plasma enhanced CVD. For the present work, we focus on the radio frequency (BE) discharge characteristics of gas mixtures used in nitride deposition (for example, WF6 and ammonia). Because the radial variations for a standard 200 mm, parallel plate reactor are limited to a small zone near the edges of the electrodes, a 1-D (one-dimensional) analysis is considered. This model consists of a self-consistent, 3-D (three-dimensional) moment fluid simulation that solves the continuity, momentum, and energy equations for neutral and charged species. The results in terms of plasma structure, radical concentrations, and local deposition rate will be presented. We will also compare the 1-D results with those obtained from a 2-D hybrid plasma equipment model (HPEM) developed at the University of Illinois.

  10. Destruction of Bacterial Biofilms Using Gas Discharge Plasma

    NASA Astrophysics Data System (ADS)

    Abramzon, Nina

    2005-03-01

    Biofilms are bacterial communities embedded in an exopolysaccharidic matrix with a complex architectural structure. Bacteria in biofilms show different properties from those in free life thus, conventional methods of killing bacteria are often ineffective with biofilms. The use of plasmas potentially offers an alternative to conventional sterilization methods since plasmas contain a mixture of charged particles, chemically reactive species, and UV radiation. 4 and 7 day-old biofilms were produced using two bacterial species: Rhizobium gallicum and Chromobacterium violaceum. Gas discharge plasma was produced by using an AtomfloTM reactor (Surfx Technologies) and bacterial biofilms were exposed to it for different periods of time. Our results show that a 10-minute plasma treatment was able to kill 100% of the cells in most cases. Optical emission spectroscopy was used to study plasma composition which is then correlated with the effectiveness of killing. These results indicate the potentiality of plasma as an alternative sterilization method. Supported by CSuperb.

  11. Transport mechanisms of metastable and resonance atoms in a gas discharge plasma

    NASA Astrophysics Data System (ADS)

    Golubovskii, Yu; Gorchakov, S.; Uhrlandt, D.

    2013-04-01

    Atoms in electronically excited states are of significant importance in a large number of different gas discharges. The spatio-temporal distribution particularly of the lower excited states, the metastable and resonance ones, influences the overall behavior of the plasma because of their role in the ionization and energy budget. This article is a review of the theoretical and experimental studies on the spatial formation and temporal evolution of metastable and resonance atoms in weakly ionized low-temperature plasmas. Therefore, the transport mechanisms due to collisional diffusion and resonance radiation are compared step by step. The differences in formation of spatio-temporal structures of metastable and resonance atoms in plasmas are attributed to these different transport mechanisms. The analysis is performed by obtaining solutions of the diffusion and radiation transport equations. Solutions of stationary and non-stationary problems by decomposition over the eigenfunctions of the corresponding operators showed that there is, on the one hand, an effective suppression of the highest diffusion modes and, on the other hand, a survival of the highest radiation modes. The role of the highest modes is illustrated by examples. In addition, the differences in the Green functions for the diffusion and radiation transport operators are discussed. Numerical methods for the simultaneous solution of the balance equations for metastable and resonance atoms are proposed. The radiation transport calculations consider large absorption coefficients according to the Lorentz contour of a spectral line. Measurements of the distributions of metastable and resonance atoms are reviewed for a larger number of discharge conditions, i.e. in the positive column plasma, afterglow plasma, constricted pulsed discharge, stratified discharge, magnetron discharge, and in a discharge with a cathode spot.

  12. 46 CFR 153.462 - Static discharges from inert gas systems.

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... gas systems. An inert gas system on a tank that carries a flammable or combustible cargo must not... 46 Shipping 5 2013-10-01 2013-10-01 false Static discharges from inert gas systems. 153.462... CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design...

  13. 46 CFR 153.462 - Static discharges from inert gas systems.

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... gas systems. An inert gas system on a tank that carries a flammable or combustible cargo must not... 46 Shipping 5 2014-10-01 2014-10-01 false Static discharges from inert gas systems. 153.462... CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design...

  14. 46 CFR 153.462 - Static discharges from inert gas systems.

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... gas systems. An inert gas system on a tank that carries a flammable or combustible cargo must not... 46 Shipping 5 2012-10-01 2012-10-01 false Static discharges from inert gas systems. 153.462... CARGOES SHIPS CARRYING BULK LIQUID, LIQUEFIED GAS, OR COMPRESSED GAS HAZARDOUS MATERIALS Design...

  15. Growth of arc in high-pressure, pulsed glow discharge by gas density depletion

    NASA Astrophysics Data System (ADS)

    Imada, Go; Yatsui, Kiyoshi; Masuda, Wataru

    2000-10-01

    Effects of gas density depletion on arc formation of high-pressure, pulsed glow discharge have been investigated by eliminating the other factors which may affect the discharge stability, such as shock waves, residual ions, electrode heating, and discharge products. The gas density depletion has been simulated by utilizing a subsonic gas flow between the curved electrodes combined with a convergent nozzle and a divergent diffuser. A comparison has been made on the discharge in the aerodynamically created gas density depletion with the second discharge in the double-pulse discharge within a stable gas. We have found that the large gas density depletion, Δρ/ρ0˜-3.6% corresponding to a pulse repetition rate (PRR) of ˜50 Hz, tends to cause an arc-like filament or an arc without the shocks, ions, electrode heating, and products. However, the second discharge in the double-pulse discharge becomes an arc in much smaller gas density depletion (Δρ/ρ0˜-1.2% corresponding to PRR ˜3 Hz). Therefore, the collapse of high-pressure, pulsed glow discharge is most likely caused by some factor other than the gas density depletion.

  16. Particle-in-cell modeling of gas-confined barrier discharge

    NASA Astrophysics Data System (ADS)

    Levko, Dmitry; Raja, Laxminarayan L.

    2016-04-01

    Gas-confined barrier discharge is studied using the one-dimensional Particle-in-Cell Monte Carlo Collisions model for the conditions reported by Guerra-Garcia and Martinez-Sanchez [Appl. Phys. Lett. 106, 041601 (2015)]. Depending on the applied voltage, two modes of discharge are observed. In the first mode, the discharge develops in the entire interelectrode gap. In the second mode, the discharge is ignited and develops only in the gas layer having smaller breakdown voltage. The one-dimensional model shows that for the conditions considered, there is no streamer stage of breakdown as is typical for a traditional dielectric barrier discharge.

  17. Effects of ionic liquid electrode on pulse discharge plasmas in the wide range of gas pressures

    SciTech Connect

    Chen Qiang; Hatakeyama, Rikizo; Kaneko, Toshiro

    2010-11-15

    Gas-liquid interfacial pulse discharge plasmas are generated in the wide range of gas pressures, where an ionic liquid is used as the liquid electrode. By analyzing the characteristics of discharge voltage and current, the discharge mechanisms at low and high pressures are found to be dominated by secondary electron emission and first Townsend ionization, respectively. Therefore, the discharge properties at low and high pressures are mainly determined by the cathode material and the discharge gas type, respectively. Furthermore, the plasma properties are investigated by a double Langmuir probe. The density of the positive pulse plasma is found to be much smaller than that of the negative pulse plasma, although the discharge voltage and current of the negative and positive pulse plasmas are of the same order of magnitude. The positive pulse discharge plasma is considered to quickly diffuse onto the chamber wall from the radially central region due to its high plasma potential compared with that in the peripheral region.

  18. Numerical investigation on operation mode influenced by external frequency in atmospheric pressure barrier discharge

    SciTech Connect

    Wang Qi; Sun Jizhong; Wang Dezhen

    2011-10-15

    The influence of external driving frequency on the discharge mode in the dielectric barrier discharge was investigated with a two-dimensional, self-consistent fluid model. The simulation results show that the helium discharge exhibits three operation modes: Townsend, homogeneous glow, and local glow discharges from the lower frequency (1 kHz) to the higher frequency (100 kHz) under discharge parameters specified in this work. The discharge operates in a Townsend mode when the driving frequency varies from 1 to about 7 kHz; while it exhibits homogenous glow characteristics in an approximate range from 7 to 65 kHz; when the external frequency exceeds 65 kHz, it turns into a local glow discharge. The effects of external driving frequency on the discharge mode were revealed and the physical reasons were discussed.

  19. 46 CFR 153.462 - Static discharges from inert gas systems.

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Static discharges from inert gas systems. 153.462... Equipment Special Requirements for Flammable Or Combustible Cargoes § 153.462 Static discharges from inert... create static arcing as the inert gas is injected into the tank....

  20. 46 CFR 153.462 - Static discharges from inert gas systems.

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Static discharges from inert gas systems. 153.462... Equipment Special Requirements for Flammable Or Combustible Cargoes § 153.462 Static discharges from inert... create static arcing as the inert gas is injected into the tank....

  1. 21 CFR 1020.20 - Cold-cathode gas discharge tubes.

    Code of Federal Regulations, 2010 CFR

    2010-04-01

    ... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Cold-cathode gas discharge tubes. 1020.20 Section...) RADIOLOGICAL HEALTH PERFORMANCE STANDARDS FOR IONIZING RADIATION EMITTING PRODUCTS § 1020.20 Cold-cathode gas discharge tubes. (a) Applicability. The provisions of this section are applicable to cold-cathode...

  2. Characteristics of excitation discharge of an excimer laser in gas density depletion

    NASA Astrophysics Data System (ADS)

    Imada, Go; Masuda, Wataru; Yatsui, Kiyoshi

    1998-12-01

    The influences of gas density depletion on the highly- repetitive, high-pressure, pulsed glow discharge for excitation of excimer laser have been investigated eliminating the other instabilities, such as shock waves, residual ions, discharge products and electrode heating. The gas density depletion is simulated by utilizing a subsonic flow between the curved electrodes. The comparison has been made on the discharge occurred in the presence of the gas density depletion with the second discharge on the double-pulse experiment. We have found that the big gas density non uniformity, (Delta) (rho) /(rho) 0 approximately 3.6% corresponding to a pulse repetition rate (PRR) of approximately 20 Hz, tends to cause the arc discharge without the shocks, ions, discharge products and electrode heating. On the other hand, the second discharge on the double-pulse experiment becomes arc discharge in much smaller non uniformity ((Delta) (rho) /(rho) 0 approximately 1.2% corresponding to PRR approximately 3 Hz). The arc discharge in the double-pulse experiment might be driven by the residual ions and/or discharge products other than gas density depletion except for PRR greater than 20 Hz.

  3. Operating a fuel cell using landfill gas

    SciTech Connect

    Trippel, C.E.; Preston, J.L. Jr.; Trocciola, J.; Spiegel, R.

    1996-12-31

    An ONSI PC25{trademark}, 200 kW (nominal capacity) phosphoric acid fuel cell operating on landfill gas is installed at the Town of Groton Flanders Road landfill in Groton, Connecticut. This joint project by the Connecticut Light & Power Company (CL&P) which is an operating company of Northeast Utilities, the Town of Groton, International Fuel Cells (IFC), and the US EPA is intended to demonstrate the viability of installing, operating and maintaining a fuel cell operating on landfill gas at a landfill site. The goals of the project are to evaluate the fuel cell and gas pretreatment unit operation, test modifications to simplify the GPU design and demonstrate reliability of the entire system.

  4. Inception of Snapover and Gas Induced Glow Discharges

    NASA Technical Reports Server (NTRS)

    Galofaro, J. T.; Vayner, B. V.; Degroot, W. A.; Ferguson, D. C.; Thomson, C. D.; Dennison, J. R.; Davies, R. E.

    2000-01-01

    Ground based experiments of the snapover phenomenon were conducted in the large vertical simulation chamber at the Glenn Research Center (GRC) Plasma Interaction Facility (PIF). Two Penning sources provided both argon and xenon plasmas for the experiments. The sources were used to simulate a variety of ionospheric densities pertaining to a spacecraft in a Low Earth Orbital (LEO) environment. Secondary electron emission is believed responsible for dielectric surface charging, and all subsequent snapover phenomena observed. Voltage sweeps of conductor potentials versus collected current were recorded in order to examine the specific charging history of each sample. The average time constant for sample charging was estimated between 25 and 50 seconds for all samples. It appears that current drops off by approximately a factor of 3 over the charging time of the sample. All samples charged in the forward and reverse bias directions, demonstrated hysteresis. Current jumps were only observed in the forward or positive swept voltage direction. There is large dispersion in tile critical snapover potential when repeating sweeps on any one sample. The current ratio for the first snapover region jumps between 2 and 4.6 times, with a standard deviation less than 1.6. Two of the samples showed even larger current ratios. It is believed the second large snapover region is due to sample outgassing. Under certain preset conditions, namely at the higher neutral gas background pressures, a perceptible blue-green glow was observed around the conductor. The glow is believed to be a result of secondary electrons undergoing collisions with an expelled tenuous cloud of gas, that is outgassed from the sample. Spectroscopic measurements of the glow discharge were made in an attempt to identify specific lines contributing to the observed glow.

  5. Simulations of Electron Density Perturbations in a Gas Discharge

    NASA Astrophysics Data System (ADS)

    Caplinger, James; Sotnikov, Vladimir; Main, Daniel

    2015-11-01

    Beginning with the idealized case of the Pierce diode, a series of particle-in-cell (PIC) simulations are conducted in order to characterize density perturbations in a laboratory gas discharge. This work is conducted to support future experimental investigations into electromagnetic scattering off of electron density perturbations excited by plasma flows. As a first step, 2D PIC simulations were conducted for the Pierce diode case, which is a simple model that exploits instabilities of a monochromatic electron beam between two grounded electrodes. These results were compared to the standard analytical solution. Departing from this idealized case we will include in the simulations electron-neutral collisions, particle creation from ionization, as well as an electric field generated by biased electrodes. A parameter study of electric field strength and collision frequency will be performed for values approaching the Pierce diode as well as extending to cases of expected laboratory parameters. If we can extract physical density spectra from simulations with parameters approaching experimental values, it may be possible to analyze electromagnetic scattering characteristics.

  6. Study of deposit associated with discharge in micro-pixel gas chamber

    NASA Astrophysics Data System (ADS)

    Homma, Y.; Ochi, A.; Moriya, K.; Matsuda, S.; Yoshida, K.; Kobayashi, S.

    2009-02-01

    We found some deposits associated with discharge on dielectric (polyimide) substrates in "Micro-Pixel Gas Chambers" ( μ-PIC) operating with Ar/C2H6 90/10. Secondary electron images taken with a scanning electron microscope (SEM) revealed that they were a conductive material. Auger electron spectroscopy clearly showed that their main component was carbon (98%). Their origin was clarified using spark tests in which a single pixel was sparked a specific number of times. Secondary electron images clearly showed that discharge occurred in the narrow gaps between the electrodes. With a Ar/C2H6 50/50 gas mixture, the amount of carbon deposited depended on the number of sparks. The drop in the applied voltage after the test depended on the number of sparks. With pure N2 gas, no deposits were clearly found, however, a decrease in the applied voltage after the tests was observed. This can be attributed to carbonization of the polyimide surface. Although the SEM images did not show clear proof of this, this carbonization could contribute much less than the ethane dissociation.

  7. Zero Discharge Water Management for Horizontal Shale Gas Well Development

    SciTech Connect

    Paul Ziemkiewicz; Jennifer Hause; Raymond Lovett; David Locke Harry Johnson; Doug Patchen

    2012-03-31

    Hydraulic fracturing technology (fracking), coupled with horizontal drilling, has facilitated exploitation of huge natural gas (gas) reserves in the Devonian-age Marcellus Shale Formation (Marcellus) of the Appalachian Basin. The most-efficient technique for stimulating Marcellus gas production involves hydraulic fracturing (injection of a water-based fluid and sand mixture) along a horizontal well bore to create a series of hydraulic fractures in the Marcellus. The hydraulic fractures free the shale-trapped gas, allowing it to flow to the well bore where it is conveyed to pipelines for transport and distribution. The hydraulic fracturing process has two significant effects on the local environment. First, water withdrawals from local sources compete with the water requirements of ecosystems, domestic and recreational users, and/or agricultural and industrial uses. Second, when the injection phase is over, 10 to 30% of the injected water returns to the surface. This water consists of flowback, which occurs between the completion of fracturing and gas production, and produced water, which occurs during gas production. Collectively referred to as returned frac water (RFW), it is highly saline with varying amounts of organic contamination. It can be disposed of, either by injection into an approved underground injection well, or treated to remove contaminants so that the water meets the requirements of either surface release or recycle use. Depending on the characteristics of the RFW and the availability of satisfactory disposal alternatives, disposal can impose serious costs to the operator. In any case, large quantities of water must be transported to and from well locations, contributing to wear and tear on local roadways that were not designed to handle the heavy loads and increased traffic. The search for a way to mitigate the situation and improve the overall efficiency of shale gas production suggested a treatment method that would allow RFW to be used as make

  8. Hydrate Control for Gas Storage Operations

    SciTech Connect

    Jeffrey Savidge

    2008-10-31

    The overall objective of this project was to identify low cost hydrate control options to help mitigate and solve hydrate problems that occur in moderate and high pressure natural gas storage field operations. The study includes data on a number of flow configurations, fluids and control options that are common in natural gas storage field flow lines. The final phase of this work brings together data and experience from the hydrate flow test facility and multiple field and operator sources. It includes a compilation of basic information on operating conditions as well as candidate field separation options. Lastly the work is integrated with the work with the initial work to provide a comprehensive view of gas storage field hydrate control for field operations and storage field personnel.

  9. Systematic investigation of the barrier discharge operation in helium, nitrogen, and mixtures: discharge development, formation and decay of surface charges

    NASA Astrophysics Data System (ADS)

    Tschiersch, R.; Bogaczyk, M.; Wagner, H.-E.

    2014-09-01

    As a logical extension to previous investigations of the barrier discharge (BD) in helium and nitrogen, the present work reports on the operation in any mixtures of both pure gases. Using a well-established plane-parallel discharge cell configuration allows to study the influence of the He/N2 mixing ratio on the formation of different discharge modes. Their characterization was made by measuring the discharge emission development together with the formation and decay of surface charges on a bismuth silicon oxide (Bi12SiO20, BSO) crystal. This was realized by the simultaneous application of the spatio-temporally resolved optical emission spectroscopy, and the electro-optic Pockels effect in combination with a CCD high speed camera. The existence diagram for diffuse and filamentary BDs was determined by varying the amplitude and shape of the applied voltage. Over the entire range of the He/N2 ratio, the diffuse mode can be operated at moderate voltage amplitudes whereas filamentation occurs at significant overvoltage and is favoured by a high voltage slew rate. Irrespective of the discharge mode, the overall charge transfer during a discharge breakdown is found to be in excellent agreement with the amount of accumulated surface charges. An exponential decay of the surface charge deposited on the BSO crystal is induced by LED illumination beyond a typical discharge cycle. During the decay process, a broadening of the radial profiles of positive as well as negative surface charge spots originating from previous microdischarges is observed. The investigations contribute to a better understanding of the charge accumulation at a dielectric.

  10. Harmonic distortion and power factor assessment in city street gas discharge lamps

    SciTech Connect

    Rios, S.; Castaneda, R.; Veas, D.

    1996-04-01

    The current and voltage harmonic spectrum, and power factor in gas discharge lamps: Sodium (Na)-high pressure and Mercury (Hg) in actual use in public street lighting have been measured. A sample of nearby 360 gas discharge lamps (Na, Hg) of different rated power was obtained by simple random sampling over a universe of approximately 15,000 lamps. An equivalent current harmonic spectrum for gas discharge lamps is proposed, which is independent of the type of gas and the lamp rated power. This current spectrum can be used to integrate gas discharge lamp models for harmonic distortion level assessment in distribution networks. The relation of this equivalent current harmonic spectrum with: (1) lamp voltage waveform, (2) type of lamp (Na, Hg), and (3) power factor-capacitor lamp, is analyzed.

  11. Potential Industrial Applications of the One Atmosphere Uniform Glow Discharge Plasma (OAUGDP) Operating in Ambient Air

    NASA Astrophysics Data System (ADS)

    Reece Roth, J.

    2004-11-01

    The majority of industrial plasma processing with glow discharges has been conducted at pressures below 10 torr. This tends to limit applications to high value workpieces as a result of the high capital cost of vacuum systems and the production constraints of batch processing. It has long been recognized that glow discharge plasmas would play a much larger industrial role if they could be generated at one atmosphere. The One Atmosphere Uniform Glow Discharge Plasma (OAUGDP), developed at the University of Tennessee's Plasma Sciences Laboratory, is a non-thermal RF plasma operating on displacement currents with the time-resolved characteristics of a classical low pressure DC normal glow discharge. As a glow discharge, the OAUGDP operates with maximum electrical efficiency at the Stoletow point, where the energy input per ion-electron pair is a minimum [1, 2]. Several interdisciplinary teams have investigated potential applications of the OAUGDP. These teams included collaborators from the UTK Textiles and Nonwovens Development Center (TANDEC), and the Departments of Electrical and Computer Engineering, Microbiology, and Food Science and Technology, as well as the NASA Langley Research Center. The potential applications of the OAUGDP have all been at one atmosphere and room temperature, using air as the working gas. These applications include sterilizing medical and dental equipment; sterilizable air filters to deal with the "sick building syndrome"; removal of soot from Diesel engine exhaust; subsonic plasma aerodynamic effects, including flow re-attachment to airfoils and boundary layer modification; electrohydrodynamic (EDH) flow control of working gases; increasing the surface energy of materials; improving the adhesion of paints and electroplated layers: improving the wettability and wickability of fabrics; stripping of photoresist; and plasma deposition and directional etching of potential microelectronic relevance. [1] J. R. Roth, Industrial Plasma Engineering

  12. Self-organized patterns in successive bifurcations in planar semiconductor-gas-discharge device

    NASA Astrophysics Data System (ADS)

    Astrov, Yu. A.; Lodygin, A. N.; Portsel, L. M.

    2015-03-01

    The formation of dissipative structures is investigated in a planar semiconductor-gas-discharge device at room temperature. The width of the discharge gap is about 1 mm. The gap is filled with nitrogen at a pressure that corresponds to the discharge operation at the right branch of the Paschen curve. Wafers of semi-insulating GaAs that exhibit linear transport in the whole range of voltage and current studied are used as semiconductor electrodes. In addition to the earlier investigated Andronov-Hopf bifurcation, a different mode of self-organization of the device is observed, where the transport of charge proceeds through an ensemble of pulsating current filaments. The corresponding critical current for the present bifurcation does not depend on the polarity of the bias voltage, while the spatiotemporal dynamics of a pattern differs substantially for a change in the polarity. Pulsating filaments can form a spatially ordered pattern when the GaAs electrode is under the positive potential. We also observe self-organization modes, where pulsating filaments form an irregular spatiotemporal dynamics of a pattern. The data obtained are briefly discussed in the frame of corresponding theoretical results in the field.

  13. Efficient gas lasers pumped by double-discharge circuits with semiconductor opening switch

    NASA Astrophysics Data System (ADS)

    Panchenko, Alexei N.; Tarasenko, Victor F.

    2012-01-01

    A review of applications of double-discharge circuits based on generators with inductive energy storage (IES) and semiconductor opening switches (SOS) for efficient excitation of different gas lasers is presented. Using a pre-pulse-sustainer circuit technique based on inductive energy storage and semiconductor opening switch generators allows the formation of a pre-pulse with high amplitude and short rise-time and provides a sharp increase of discharge current which significantly improves discharge stability and life-time of the volume discharge in gas mixtures containing halogens. A pre-pulse with high pumping power forms a high-density discharge plasma and an inversion population in gas mixtures under study within ∼10 ns and provides both early onset of lasing and conditions for efficient excitation of an active medium from the storage capacitor. As a result, pulse duration, output energy and efficiency of the lasers under study were improved.

  14. [Removal of SO2 from flue gas by water vapor DC corona discharge].

    PubMed

    Sun, Ming; Wu, Yan

    2006-07-01

    The influence of several factors on removal rate of SO2 from flue gas in unsaturated water vapor DC corona discharge was researched. Furthermore, the experiments of the removal rate of SO2 in pulsed discharge increased by water vapor DC corona discharge plasma were conducted. The experiment system is supplied with multi-nozzle-plate electrodes and the flow of simulated flue gas is under 70 m3/h. The results show that removal rate of SO2 can be improved by increasing the concentration of water vapor, intensity of electric field or decreasing flow of simulated flue gas. In unsaturated water vapor DC corona discharge, removal rate of SO2 can be improved by 10%, when NH3 is added as NH3 and SO2 is in a mole ratio of two to one, it can reach 60%. The removal rate of SO2 can be increased by 5% in pulsed corona discharge and reach above 90%. PMID:16881295

  15. Effect of hydrogen ratio on plasma parameters of N2-H2 gas mixture glow discharge

    NASA Astrophysics Data System (ADS)

    El-Brulsy, R. A.; Abd Al-Halim, M. A.; Abu-Hashem, A.; Rashed, U. M.; Hassouba, M. A.

    2012-05-01

    A dc plane glow discharge in a nitrogen-hydrogen (N2-H2) gas mixture has been operated at discharge currents of 10 and 20 mA. The electron energy distribution function (EEDF) at different hydrogen concentrations is measured. A Maxwellian EEDF is found in the positive column region, while in both cathode fall and negative glow regions, a non-Maxwellian one is observed. Langmuir electric probes are used at different axial positions, gas pressures, and hydrogen concentrations to measure the electron temperature and plasma density. The electron temperature is found to increase with increasing H2 concentration and decrease with increasing both the axial distance from the cathode and the mixture pressure. At first, with increasing distance from the cathode, the ion density decreases, while the electron density increases; then, as the anode is further approached, they remain nearly constant. At different H2 concentrations, the electron and ion densities decrease with increasing the mixture pressure. Both the electron and ion densities slightly decrease with increasing H2 concentration.

  16. Nonlinear transport of semi-insulating GaAs in a semiconductor gas discharge structure

    NASA Astrophysics Data System (ADS)

    Yücel Kurt, H.; Salamov, B. G.

    2007-12-01

    Nonlinear transport of a semi-insulating (SI) GaAs photodetector in a semiconductor gas discharge structure (SGDS) is studied experimentally for a wide range of gas pressures p, interelectrode distances d and different diameters D of the detector areas. While being driven with a stationary voltage, the system generates current and discharge light emission (DLE) instabilities with different amplitudes of the oscillations. The transformation of the profile and amplitude of the current density of the filaments in the different regions of the current-voltage characteristic (CVC) has been studied. Instabilities of spatially non-uniform distributions resulting in the formation of multiple current filaments with increasing voltages above the critical values have been observed. It is shown that the interelectrode distance only plays a passive role and is not responsible for the appearance of the DLE instability under the experimental conditions. At the same time, the expanded range of current and DLE oscillations are observed for different diameters D of the infrared (IR) photodetector areas. An SGDS with an N-shaped CVC is analysed using both the current and DLE data which show the electrical instability in the GaAs photodetector. It is found that the application of high feeding voltage to this photodetector gives rise to a non-uniform spatial distribution of the DLE, which disturbs the operation of the system. The experiment also presents a new method to study and visualize the electrical instabilities in a high-resistivity IR photodetector of large diameter.

  17. Natural gas in Lake Erie: a reconnaissance survey of discharges from an offshore drilling rig

    SciTech Connect

    Ferrante, J.G.; Dettmann, E.H.; Parker, J.I.

    1980-10-01

    Field studies were conducted May 28-June 1, 1979, to determine the chemical composition and physical behavior of discharges from an offshore gas drilling rig in the central basin of Lake Erie. The drilling operation was observed for four days, from rig jackup to the circulation of mud through the borehole after drilling had been completed. Resuspension studies using nephelometry, supplemented with chemical analyses, indicated little resuspension of lake bottom materials or release of metals to the water column during rig jack-up. Portions of the turbidity plumes generated during drilling were buoyant. Three surface turbidity plumes were mapped with nephelometry to a point at which particulate concentrations reached background levels in the Lake. Detectable plumes were approx. 400 to 1500 m in length and had maximum widths < 230 m. A chemical survey conducted in the plume during early gas shows indicated that discharged inorganic chemical species were rapidly diluted to background concentrations and that methane and ethane concentrations were substantially reduced within 330 m of the rig. There was no evidence of carbon tetrachloride extractable hydrocarbons (CTEH) above background concentrations during this chemical plume survey. However, a pair of water samples taken within 100 m of the rig approximately 3 hours after drilling of the target zone was completed had CTEH concentrations that were a factor of 2.4 above background.

  18. Initiation of long, free-standing z discharges by CO2 laser gas heating

    NASA Astrophysics Data System (ADS)

    Niemann, C.; Tauschwitz, A.; Penache, D.; Neff, S.; Knobloch, R.; Birkner, R.; Presura, R.; Hoffmann, D. H. H.; Yu, S. S.; Sharp, W. M.

    2002-01-01

    High current discharge channels can neutralize both current and space charge of very intense ion beams. Therefore, they are considered an interesting solution for final focus and beam transport in a heavy ion beam fusion reactor. At the Gesellschaft für Schwerionenforschung accelerator facility, 50 cm long, free-standing discharge channels were created in a 60 cm diameter metallic chamber. Discharges with currents of 45 kA in 2 to 25 mbar ammonia (NH3) gas are initiated by a CO2 laser pulse along the channel axis before the capacitor bank is triggered. Resonant absorption of the laser, tuned to the v2 vibration of the ammonia molecule, causes strong gas heating. Subsequent expansion and rarefaction of the gas prepare the conditions for a stable discharge to fulfill the requirements for ion beam transport. The influence of an electric prepulse on the high current discharge was investigated. This article describes the laser-gas interaction and the discharge initiation mechanism. We found that channels are magnetohydrodynamic stable up to currents of 45 kA, measured by fast shutter and streak imaging techniques. The rarefaction of the laser heated gas is studied by means of a one-dimensional Lagrangian fluid code (CYCLOPS) and is identified as the dominant initiation mechanism of the discharge.

  19. Binary and ternary gas mixtures for use in glow discharge closing switches

    DOEpatents

    Hunter, Scott R.; Christophorou, Loucas G.

    1990-01-01

    Highly efficient binary and ternary gas mixtures for use in diffuse glow discharge closing switches are disclosed. The binary mixtures are combinations of helium or neon and selected perfluorides. The ternary mixtures are combinations of helium, neon, or argon, a selected perfluoride, and a small amount of gas that exhibits enhanced ionization characteristics. These mixtures are shown to be the optimum choices for use in diffuse glow discharge closing switches by virtue of the combined physio-electric properties of the mixture components.

  20. Gas-discharge probe microscopy of water-carrying channels in wood

    NASA Astrophysics Data System (ADS)

    Ivanov-Omskii, V. I.; Ivanova, E. I.

    2012-04-01

    We have used a gas-discharge imaging technique to study the water transport channels (tracheids) in wood samples. Results obtained for the samples of bitch and aspen show features of this variant of the probe microscopy and show its additional possibilities as compared to optical microscopy. It is concluded that gas-discharge probe microscopy can be used for additional diagnostics of the structure of plant and animal tissues.

  1. The inactivation of Chlorella spp. with dielectric barrier discharge in gas-liquid mixture

    NASA Astrophysics Data System (ADS)

    Song, Dan; Sun, Bing; Zhu, Xiaomei; Yan, Zhiyu; Liu, Hui; Liu, Yongjun

    2013-03-01

    The inactivation of Chlorella spp. with high voltage and frequency pulsed dielectric barrier discharge in hybrid gas-liquid reactor with a suspension electrode was studied experimentally. In the hybrid gas-liquid reactor, a steel plate was used as high voltage electrode while a quartz plate as a dielectric layer, another steel plate placing in the aqueous solution worked as a whole ground electrode. A suspension electrode is installed near the surface of solution between high voltage and ground electrode to make the dielectric barrier discharge uniform and stable, the discharge gap was between the quartz plate and the surface of the water. The effect of peak voltage, treatment time, the initial concentration of Chlorella spp. and conductivity of solution on the inactivation rate of Chlorella spp. was investigated, and the inactivation mechanism of Chlorella spp. preliminarily was studied. Utilizing this system inactivation of Chlorella spp., the inactivation rate increased with increasing of peak voltage, treatment time and electric conductivity. It was found that the inactivation rate of Chlorella spp. arrived at 100% when the initial concentration was 4 × 106 cells mL-1, and the optimum operation condition required a peak voltage of 20 kV, a treatment time of 10 min and a frequency of 7 kHz. Though the increasing of initial concentration of the Chlorella spp. contributed to the addition of interaction probability between the Chlorella spp. and O3, H2O2, high-energy electrons, UV radiation and other active substances, the total inactivation number raise, but the inactivation rate of the Chlorella spp. decreased.

  2. 33 CFR 151.79 - Operating requirements: Discharge of sewage within Antarctica.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... of sewage within Antarctica. 151.79 Section 151.79 Navigation and Navigable Waters COAST GUARD... Pollution and Sewage § 151.79 Operating requirements: Discharge of sewage within Antarctica. (a) A vessel certified to carry more than 10 persons must not discharge untreated sewage into the sea within 12...

  3. 33 CFR 151.79 - Operating requirements: Discharge of sewage within Antarctica.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... of sewage within Antarctica. 151.79 Section 151.79 Navigation and Navigable Waters COAST GUARD... Pollution and Sewage § 151.79 Operating requirements: Discharge of sewage within Antarctica. (a) A vessel certified to carry more than 10 persons must not discharge untreated sewage into the sea within 12...

  4. 33 CFR 151.79 - Operating requirements: Discharge of sewage within Antarctica.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... of sewage within Antarctica. 151.79 Section 151.79 Navigation and Navigable Waters COAST GUARD... Pollution and Sewage § 151.79 Operating requirements: Discharge of sewage within Antarctica. (a) A vessel certified to carry more than 10 persons must not discharge untreated sewage into the sea within 12...

  5. 33 CFR 151.79 - Operating requirements: Discharge of sewage within Antarctica.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... of sewage within Antarctica. 151.79 Section 151.79 Navigation and Navigable Waters COAST GUARD... Pollution and Sewage § 151.79 Operating requirements: Discharge of sewage within Antarctica. (a) A vessel certified to carry more than 10 persons must not discharge untreated sewage into the sea within 12...

  6. 33 CFR 151.79 - Operating requirements: Discharge of sewage within Antarctica.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... of sewage within Antarctica. 151.79 Section 151.79 Navigation and Navigable Waters COAST GUARD... Pollution and Sewage § 151.79 Operating requirements: Discharge of sewage within Antarctica. (a) A vessel certified to carry more than 10 persons must not discharge untreated sewage into the sea within 12...

  7. 33 CFR 151.67 - Operating requirements: Discharge of plastic prohibited.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... of plastic prohibited. 151.67 Section 151.67 Navigation and Navigable Waters COAST GUARD, DEPARTMENT... Sewage § 151.67 Operating requirements: Discharge of plastic prohibited. No person on board any ship may discharge into the sea, or into the navigable waters of the United States, plastic or garbage mixed...

  8. 33 CFR 151.67 - Operating requirements: Discharge of plastic prohibited.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... of plastic prohibited. 151.67 Section 151.67 Navigation and Navigable Waters COAST GUARD, DEPARTMENT... Sewage § 151.67 Operating requirements: Discharge of plastic prohibited. No person on board any ship may discharge into the sea, or into the navigable waters of the United States, plastic or garbage mixed...

  9. 33 CFR 151.67 - Operating requirements: Discharge of plastic prohibited.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ... of plastic prohibited. 151.67 Section 151.67 Navigation and Navigable Waters COAST GUARD, DEPARTMENT... Sewage § 151.67 Operating requirements: Discharge of plastic prohibited. No person on board any ship may discharge into the sea, or into the navigable waters of the United States, plastic or garbage mixed...

  10. 33 CFR 151.67 - Operating requirements: Discharge of plastic prohibited.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... of plastic prohibited. 151.67 Section 151.67 Navigation and Navigable Waters COAST GUARD, DEPARTMENT... Sewage § 151.67 Operating requirements: Discharge of plastic prohibited. No person on board any ship may discharge into the sea, or into the navigable waters of the United States, plastic or garbage mixed...

  11. 33 CFR 151.67 - Operating requirements: Discharge of plastic prohibited.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... of plastic prohibited. 151.67 Section 151.67 Navigation and Navigable Waters COAST GUARD, DEPARTMENT... Sewage § 151.67 Operating requirements: Discharge of plastic prohibited. No person on board any ship may discharge into the sea, or into the navigable waters of the United States, plastic or garbage mixed...

  12. 33 CFR 151.69 - Operating requirements: Discharge of garbage outside special areas.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., GARBAGE, MUNICIPAL OR COMMERCIAL WASTE, AND BALLAST WATER Implementation of MARPOL 73/78 and the Protocol... Pollution and Sewage § 151.69 Operating requirements: Discharge of garbage outside special areas. (a) Except...; and (3) 100 nautical miles and the maximum water depth possible for animal carcasses. Discharge...

  13. 33 CFR 151.71 - Operating requirements: Discharge of garbage within special areas.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., GARBAGE, MUNICIPAL OR COMMERCIAL WASTE, AND BALLAST WATER Implementation of MARPOL 73/78 and the Protocol... Pollution and Sewage § 151.71 Operating requirements: Discharge of garbage within special areas. (a) When a... garbage into the water, except as allowed in this section. (b) Food wastes shall only be discharged...

  14. 33 CFR 151.71 - Operating requirements: Discharge of garbage within special areas.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ..., GARBAGE, MUNICIPAL OR COMMERCIAL WASTE, AND BALLAST WATER Implementation of MARPOL 73/78 and the Protocol... Pollution and Sewage § 151.71 Operating requirements: Discharge of garbage within special areas. (a) When a... garbage into the water, except as allowed in this section. (b) Food wastes shall only be discharged...

  15. 33 CFR 151.69 - Operating requirements: Discharge of garbage outside special areas.

    Code of Federal Regulations, 2013 CFR

    2013-07-01

    ..., GARBAGE, MUNICIPAL OR COMMERCIAL WASTE, AND BALLAST WATER Implementation of MARPOL 73/78 and the Protocol... Pollution and Sewage § 151.69 Operating requirements: Discharge of garbage outside special areas. (a) Except...; and (3) 100 nautical miles and the maximum water depth possible for animal carcasses. Discharge...

  16. Endotoxin removal by radio frequency gas plasma (glow discharge)

    NASA Astrophysics Data System (ADS)

    Poon, Angela

    2011-12-01

    Contaminants remaining on implantable medical devices, even following sterilization, include dangerous fever-causing residues of the outer lipopolysaccharide-rich membranes of Gram-negative bacteria such as the common gut microorganism E. coli. The conventional method for endotoxin removal is by Food & Drug Administration (FDA)-recommended dry-heat depyrogenation at 250°C for at least 45 minutes, an excessively time-consuming high-temperature technique not suitable for low-melting or heat-distortable biomaterials. This investigation evaluated the mechanism by which E. coli endotoxin contamination can be eliminated from surfaces during ambient temperature single 3-minute to cumulative 15-minute exposures to radio-frequency glow discharge (RFGD)-generated residual room air plasmas activated at 0.1-0.2 torr in a 35MHz electrodeless chamber. The main analytical technique for retained pyrogenic bio-activity was the Kinetic Chromogenic Limulus Amebocyte Lysate (LAL) Assay, sufficiently sensitive to document compliance with FDA-required Endotoxin Unit (EU) titers less than 20 EU per medical device by optical detection of enzymatic color development corresponding to < 0.5 EU/ml in sterile water extracts of each device. The main analytical technique for identification of chemical compositions, amounts, and changes during sequential reference Endotoxin additions and subsequent RFGD-treatment removals from infrared (IR)-transparent germanium (Ge) prisms was Multiple Attenuated Internal Reflection (MAIR) infrared spectroscopy sensitive to even monolayer amounts of retained bio-contaminant. KimaxRTM 60 mm x 15 mm and 50mm x 15mm laboratory glass dishes and germanium internal reflection prisms were inoculated with E. coli bacterial endotoxin water suspensions at increments of 0.005, 0.05, 0.5, and 5 EU, and characterized by MAIR-IR spectroscopy of the dried residues on the Ge prisms and LAL Assay of sterile water extracts from both glass and Ge specimens. The Ge prism MAIR

  17. Pilot gasification and hot gas cleanup operations

    SciTech Connect

    Rockey, J.M.; Galloway, E.; Thomson, T.A.; Rutten, J.; Lui, A.

    1995-12-31

    The Morgantown Energy Technology Center (METC) has an integrated gasification hot gas cleanup facility to develop gasification, hot particulate and desulfurization process performance data for IGCC systems. The objective of our program is to develop fluidized-bed process performance data for hot gas desulfurization and to further test promising sorbents from lab-scale screening studies at highpressure (300 psia), and temperatures (1,200{degrees}F) using coal-derived fuel gases from a fluid-bed gasifier. The 10-inch inside diameter (ID), nominal 80 lb/hr, air blown gasifier is capable of providing about 300 lb/hr of low BTU gas at 1,000{degrees}F and 425 psig to downstream cleanup devices. The system includes several particle removal stages, which provide the capability to tailor the particle loading to the cleanup section. The gas pressure is reduced to approximately 300 psia and filtered by a candle filter vessel containing up to four filter cartridges. For batch-mode desulfurization test operations, the filtered coal gas is fed to a 6-inch ID, fluid-bed reactor that is preloaded with desulfurization sorbent. Over 400 hours of gasifier operation was logged in 1993 including 384 hours of integration with the cleanup rig. System baseline studies without desulfurization sorbent and repeatability checks with zinc ferrite sorbent were conducted before testing with the then most advanced zinc titanate sorbents, ZT-002 and ZR-005. In addition to the desulfurization testing, candle filters were tested for the duration of the 384 hours of integrated operation. One filter was taken out of service after 254 hours of filtering while another was left in service. At the conclusion of testing this year it is expected that 3 candles, one each with 254, 530, and 784 hours of filtering will be available for analysis for effects of the exposure to the coal gas environment.

  18. 33 CFR 151.73 - Operating requirements: Discharge of garbage from fixed or floating platforms.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... SUBSTANCES, GARBAGE, MUNICIPAL OR COMMERCIAL WASTE, AND BALLAST WATER Implementation of MARPOL 73/78 and the... Pollution and Sewage § 151.73 Operating requirements: Discharge of garbage from fixed or floating...

  19. 33 CFR 151.73 - Operating requirements: Discharge of garbage from fixed or floating platforms.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... SUBSTANCES, GARBAGE, MUNICIPAL OR COMMERCIAL WASTE, AND BALLAST WATER Implementation of MARPOL 73/78 and the... Pollution and Sewage § 151.73 Operating requirements: Discharge of garbage from fixed or floating...

  20. 33 CFR 151.73 - Operating requirements: Discharge of garbage from fixed or floating platforms.

    Code of Federal Regulations, 2010 CFR

    2010-07-01

    ... SUBSTANCES, GARBAGE, MUNICIPAL OR COMMERCIAL WASTE, AND BALLAST WATER Implementation of MARPOL 73/78 and the... Pollution and Sewage § 151.73 Operating requirements: Discharge of garbage from fixed or floating...

  1. Impact of gas flow rate on breakdown of filamentary dielectric barrier discharges

    NASA Astrophysics Data System (ADS)

    Höft, H.; Becker, M. M.; Kettlitz, M.

    2016-03-01

    The influence of gas flow rate on breakdown properties and stability of pulsed dielectric barrier discharges (DBDs) in a single filament arrangement using a gas mixture of 0.1 vol. % O2 in N2 at atmospheric pressure was investigated by means of electrical and optical diagnostics, accompanied by fluid dynamics and electrostatics simulations. A higher flow rate perpendicular to the electrode symmetry axis resulted in an increased breakdown voltage and DBD current maximum, a higher discharge inception jitter, and a larger emission diameter of the discharge channel. In addition, a shift of the filament position for low gas flow rates with respect to the electrode symmetry axis was observed. These effects can be explained by the change of the residence time of charge carriers in the discharge region—i.e., the volume pre-ionization—for changed flow conditions due to the convective transport of particles out of the center of the gap.

  2. Discharge stabilization studies of CO laser gas mixtures in quasi-steady supersonic flow

    NASA Technical Reports Server (NTRS)

    Srinivasan, G.; Smith, J. A.

    1976-01-01

    Experiments were conducted to study the applicability of a double discharge stabilization scheme in conditions appropriate for high energy CO lasers in supersonic flows. A Ludwieg tube impulse flow facility and a ballasted capacitor bank provided essentially steady flow and discharge conditions (d.c.) for times longer than ten electrode length-flow transit times. Steady, arc-free, volume discharges were produced in a Mach 3 test cavity using an auxiliary discharge to stabilize the main discharge in N2 and He/CO mixture. A signigicant result is the lack of observed plasma E/N changes in response to auxiliary discharge current changes. Also, where glow discharges were obtained, the energy loading achieved was very much less than the threshold level required for laser operation.

  3. Initiation of long, free-standing Z-discharges by CO2 laser gas heating

    SciTech Connect

    Nieman, C.; Tauschwitz, A.; Penache, D.; Neff, S.; Knobloch, R.; Birkner, R.; Presura, R.; Hoffmann, D.H.H.; Yu, S.S.; Sharp, W.M.

    2004-04-19

    High current discharge channels can neutralize both current and space charge of very intense ion beams. Therefore they are considered as an interesting alternative for the final focus and beam transport in a heavy ion beam fusion reactor. At the GSI accelerator facility, 50 cm long, stable, free-standing discharge channels with currents in excess of 40 kA in 2 to 25 mbar ammonia (NH{sub 3}) gas are investigated for heavy ion beam transport studies. The discharges are initiated by a CO{sub 2} laser pulse along the channel axis before the discharge is triggered. Resonant absorption of the laser, tuned to the {nu}{sub 2} vibration of the ammonia molecule, causes strong gas heating. Subsequent expansion and rarefaction of the gas prepare the conditions for a stable discharge to fulfill the requirements for ion beam transport. This paper describes the laser-gas interaction and the discharge initiation mechanism. We report on the channel stability and evolution, measured by fast shutter and streak imaging techniques. The rarefaction of the laser heated gas is studied by means of a hydrocode simulation.

  4. 2D fluid simulations of discharges at atmospheric pressure in reactive gas mixtures

    NASA Astrophysics Data System (ADS)

    Bourdon, Anne

    2015-09-01

    Since a few years, low-temperature atmospheric pressure discharges have received a considerable interest as they efficiently produce many reactive chemical species at a low energy cost. This potential is of great interest for a wide range of applications as plasma assisted combustion or biomedical applications. Then, in current simulations of atmospheric pressure discharges, there is the need to take into account detailed kinetic schemes. It is interesting to note that in some conditions, the kinetics of the discharge may play a role on the discharge dynamics itself. To illustrate this, we consider the case of the propagation of He-N2 discharges in long capillary tubes, studied for the development of medical devices for endoscopic applications. Simulation results put forward that the discharge dynamics and structure depend on the amount of N2 in the He-N2 mixture. In particular, as the amount of N2 admixture increases, the discharge propagation velocity in the tube increases, reaches a maximum for about 0 . 1 % of N2 and then decreases, in agreement with experiments. For applications as plasma assisted combustion with nanosecond repetitively pulsed discharges, there is the need to handle the very different timescales of the nanosecond discharge with the much longer (micro to millisecond) timescales of combustion processes. This is challenging from a computational point of view. It is also important to better understand the coupling of the plasma induced chemistry and the gas heating. To illustrate this, we present the simulation of the flame ignition in lean mixtures by a nanosecond pulsed discharge between two point electrodes. In particular, among the different discharge regimes of nanosecond repetitively pulsed discharges, a ``spark'' regime has been put forward in the experiments, with an ultra-fast local heating of the gas. For other discharge regimes, the gas heating is much weaker. We have simulated the nanosecond spark regime and have observed shock waves

  5. Dimmable Electronic Ballast for a Gas Discharge Lamp

    NASA Technical Reports Server (NTRS)

    Raducanu, Marius; Hennings, Brian D.

    2013-01-01

    Titanium dioxide (TiO2) is the most efficient photocatalyst for organic oxidative degradation. TiO2 is effective not only in aqueous solution, but also in nonaqueous solvents and in the gas phase. It is photostable, biologically and chemically inert, and non-toxic. Low-energy UV light (approximately 375 nm, UV-A) can be used to photoactivate TiO2. TiO2 photocatalysis has been used to mineralize most types of organic compounds. Also, TiO2 photocatalysis has been effectively used in sterilization. This effectiveness has been demonstrated by its aggressive destruction of microorganisms, and aggressive oxidation effects of toxins. It also has been used for the oxidation of carbon monoxide to carbon dioxide, and ammonia to nitrogen. Despite having many attractive features, advanced photocatalytic oxidation processes have not been effectively used for air cleaning. One of the limitations of the traditional photocatalytic systems is the ballast that powers (lights) the bulbs. Almost all commercial off-the-shelf (COTS) ballasts are not dimmable and do not contain safety features. COTS ballasts light the UV lamp as bright as the bulb can be lit, and this results in shorter bulb lifetime and maximal power consumption. COTS magnetic ballasts are bulky, heavy, and inefficient. Several iterations of dimmable electronic ballasts have been developed. Some manifestations have safety features such as broken-bulb or over-temperature warnings, replace-bulb alert, logbulb operational hours, etc. Several electronic ballast boards capable of independently lighting and controlling (dimming) four fluorescent (UV light) bulbs were designed, fabricated, and tested. Because of the variation in the market bulb parameters, the ballast boards were designed with a very broad range output. The ballast boards can measure and control the current (power) for each channel.

  6. Administrative aspects of a general surgical firm: an audit of accuracy of operation lists and timeliness of discharge summaries.

    PubMed

    Aziz, M M; Corder, A P

    1996-07-01

    A one-year audit of operation lists and discharge summaries of one surgical firm showed only 1.4 percent of operation lists contained errors or omissions and only 5 percent contained abbreviations. 74.2 percent of discharge summaries were dictated within one week of discharge. A high proportion of day cases allowed 44.7 percent of the discharge summaries to be dictated on the day of operation. Close consultant and secretarial involvement in the preparation of operating lists can ensure a high degree of accuracy. Day case operation notes should be combined with a discharge letter to optimise communication with general practitioners. PMID:8943624

  7. Spark discharge method of liquid rare-gas purification

    NASA Astrophysics Data System (ADS)

    Pokachalov, S. G.; Kirsanov, M. A.; Kruglov, A. A.; Obodovski, I. M.

    1993-03-01

    The spark disharge method of liquid rare-gas purification is describe. The method is sufficiently more simple than those widely used. Physical aspects of the method are discussed, and examples of its application are presented.

  8. Gas Breakdown of Radio Frequency Glow Discharges in Helium at near Atmospheric Pressure

    NASA Astrophysics Data System (ADS)

    Liu, Xinkun; Xu, Jinzhou; Cui, Tongfei; Guo, Ying; Zhang, Jing; Shi, Jianjun

    2013-07-01

    A one-dimensional self-consistent fluid model was developed for radio frequency glow discharge in helium at near atmospheric pressure, and was employed to study the gas breakdown characteristics in terms of breakdown voltage. The effective secondary electron emission coefficient and the effective electric field for ions were demonstrated to be important for determining the breakdown voltage of radio frequency glow discharge at near atmospheric pressure. The constant of A was estimated to be 64±4 cm-1Torr-1, which was proportional to the first Townsend coefficient and could be employed to evaluate the gas breakdown voltage. The reduction in the breakdown voltage of radio frequency glow discharge with excitation frequency was studied and attributed to the electron trapping effect in the discharge gap.

  9. Effect of duty-cycles on the air plasma gas-phase of dielectric barrier discharges

    NASA Astrophysics Data System (ADS)

    Barni, R.; Biganzoli, I.; Dell'Orto, E. C.; Riccardi, C.

    2015-10-01

    An experimental investigation concerning the effects of a duty-cycle in the supply of a dielectric barrier discharge in atmospheric pressure air has been performed. Electrical characteristics of the discharge have been measured, focusing mainly on the statistical properties of the current filaments and on dielectric surface charging, both affected by the frequent repetition of breakdown imposed by the duty-cycle. Information on the gas-phase composition was gathered too. In particular, a strong enhancement in the ozone formation rate is observed when suitable long pauses separate the active discharge phases. A simulation of the chemical kinetics in the gas-phase, based on a simplified discharge modeling, is briefly described in order to shed light on the observed increase in ozone production. The effect of a duty-cycle on surface modification of polymeric films in order to increase their wettability has been investigated too.

  10. A brush-shaped air plasma jet operated in glow discharge mode at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Li, Xuechen; Bao, Wenting; Jia, Pengying; Di, Cong

    2014-07-01

    Using ambient air as working gas, a direct-current plasma jet is developed to generate a brush-shaped plasma plume with fairly large volume. Although a direct-current power supply is used, the discharge shows a pulsed characteristic. Based on the voltage-current curve and fast photography, the brush-shaped plume, like the gliding arc plasma, is in fact a temporal superposition of a moving discharge filament in an arched shape. During it moves away from the nozzle, the discharge evolves from a low-current arc into a normal glow in one discharge cycle. The emission profile is explained qualitatively based on the dynamics of the plasma brush.

  11. Toxic Gas Removal by Dielectric Discharge with Corona Effect

    SciTech Connect

    Moreno, H.; Pacheco, M.; Mercado, A.; Cruz, A.; Pacheco, J.; Yousfi, M.; Eichwald, O.; Benhenni, M.

    2006-12-04

    In this work, a theoretical and experimental study on SO2 and NOx removal by non-thermal plasma technology, more specifically a dielectric barrier (DBD) discharge combined with the Corona effect, is presented. Results obtained from a theoretical study describe the chemical kinetic model of SO2 and NOx removal processes; the effect of OH radicals in removal of both gases is noteworthy. Experimental results of de-SO2 process are reported. Also, optical emission spectroscopy study was applied on some atomic helium lines to obtain temperature of electrons in the non-thermal plasma.

  12. Fault and partial discharge location systems for gas-insulated transmission lines. Final report

    SciTech Connect

    Boggs, S.A.; Ford, G.L.; Fujimoto, N.; Stone, G.C.

    1983-12-01

    Partial discharge and faults in gas-insulated transmission line (GITL) can be difficult to locate. This report describes the development, testing, and application of systems for fault and partial discharge location in GITL. Both systems are based on timing of electromagnetic transients generated by a fault/partial discharge source. Both systems employ microcomputers to facilitate automated data acquisition and analysis. The major problems solved in developing the fault location system were coupling of high frequency signals from and between phases and isolation of high voltage short risetime signals from high speed digital logic. The problems addressed in the partial discharge location project include handling a large number of pulses which may include noise, the large dynamic range of partial discharge induced transients (> 80 dB), and achieving an accurate correlation resolution of 2 ns.

  13. Numerical simulation of operation modes in atmospheric pressure uniform barrier discharge excited by a saw-tooth voltage

    SciTech Connect

    Li Xuechen; Niu Dongying; Yin Zengqian; Fang Tongzhen; Wang Long

    2012-08-15

    The characteristics of dielectric barrier discharge excited by a saw-tooth voltage are simulated in atmospheric pressure helium based on a one-dimensional fluid model. A stepped discharge is obtained per half voltage cycle with gas gap width less than 2 mm by the simulation, which is different to the pulsed discharge excited by a sinusoidal voltage. For the stepped discharge, the plateau duration increases with increasing the voltage amplitude and decreasing the gas gap. Therefore, uniform discharge with high temporal duty ratio can be realized with small gap through increasing the voltage amplitude. The maximal densities of both electron and ion appear near the anode and the electric field is almost uniformly distributed along the gap, which indicates that the stepped discharge belongs to a Townsend mode. In contrast to the stepped discharge with small gas gap, a pulsed discharge can be obtained with large gas gap. Through analyzing the spatial density distributions of electron and ion and the electric field, the pulsed discharge is in a glow mode. The voltage-current (V-I) characteristics are analyzed for the above mentioned discharges under different gas gaps, from which the different discharge modes are verified.

  14. Numerical simulation of operation modes in atmospheric pressure uniform barrier discharge excited by a saw-tooth voltage

    NASA Astrophysics Data System (ADS)

    Li, Xuechen; Niu, Dongying; Yin, Zengqian; Fang, Tongzhen; Wang, Long

    2012-08-01

    The characteristics of dielectric barrier discharge excited by a saw-tooth voltage are simulated in atmospheric pressure helium based on a one-dimensional fluid model. A stepped discharge is obtained per half voltage cycle with gas gap width less than 2 mm by the simulation, which is different to the pulsed discharge excited by a sinusoidal voltage. For the stepped discharge, the plateau duration increases with increasing the voltage amplitude and decreasing the gas gap. Therefore, uniform discharge with high temporal duty ratio can be realized with small gap through increasing the voltage amplitude. The maximal densities of both electron and ion appear near the anode and the electric field is almost uniformly distributed along the gap, which indicates that the stepped discharge belongs to a Townsend mode. In contrast to the stepped discharge with small gas gap, a pulsed discharge can be obtained with large gas gap. Through analyzing the spatial density distributions of electron and ion and the electric field, the pulsed discharge is in a glow mode. The voltage-current (V-I) characteristics are analyzed for the above mentioned discharges under different gas gaps, from which the different discharge modes are verified.

  15. Offshore desulfurization unit permits gas lift operations

    SciTech Connect

    Cabes, A.; Elgue, J.; Tournier-Lasserve, J. )

    1992-01-13

    This paper reports on the installation of a desulfurization unit for the Tchibouela oil field, offshore Congo, which allowed produced low-pressure associated gas containing CO{sub 2} to be kept for gas lift operations while, for safety reasons, the large volume of H{sub 2}S at low pressure was removed prior to compression. Since October 1989, the world's first offshore amine sweetening unit has worked satisfactorily and continues to prove that it is an attractive production alternative. For desulfurization, a selective methyldiethanolamine (MDEA) process, developed by Elf Aquitaine, was chosen because it was the only process that met the required specifications at a low pressure of 3.5 bar (51 psi).

  16. Dynamics of dielectric barrier discharge in non-uniform gas composition investigated by laser spectroscopic measurements

    NASA Astrophysics Data System (ADS)

    Urabe, Keiichiro; Ito, Yosuke; Choi, Joon-Young; Sakai, Osamu; Tachibana, Kunihide

    2009-10-01

    It is well known that stable and glow dielectric barrier discharge (DBD) at atmospheric pressure is observed using helium gas and AC high voltage of kHz-order frequency. We have investigated the discharge mechanisms of DBDs from a view point of the spatiotemporal distributions of excited species measured by laser spectroscopic methods. In this presentation, we will show convincing arguments about the discharge model of the DBD especially having the non-uniformity of gas composition. As a DBD plasma source for atmospheric pressure processes, we have investigated an atmospheric pressure plasma jet (APPJ) using helium gas flow in ambient air, and this plasma source can be regarded as the DBD near the boundary interface of helium gas and ambient air. In this APPJ, we observed spatiotemporal distributions of excited species density inside the helium gas channel, using laser absorption spectroscopy and laser induced fluorescence, to measure the densities of helium metastable atom (2^3S1 state) and nitrogen ion (X^2σg^+ state) respectively. To study the influence of nitrogen gas contamination on the discharge profile of DBD, we have also applied CO2-laser heterodyne interferometry to measure the special distribution of electron density in parallel-plate DBD.

  17. Rapid Decomposition of Cellulose Dissolved in Ionic Liquid Using Gas-Liquid Interface Discharge

    NASA Astrophysics Data System (ADS)

    Furukawa, Shoichiro; Inoue, Nobuhiro; Ishioka, Toshio; Furuya, Kenji; Harata, Akira

    2012-07-01

    Cellulose was dissolved at 3 wt % in 15 mL of 1-allyl-3-methylimidazolium chloride ([Amim]Cl) together with 2 wt % water, and then gas-liquid interface discharge was carried out at 20 W for 200 s. As a result, 7.6% of initially dissolved cellulose decomposed and 3.9% of initially dissolved cellulose changed into reducing sugar. Adding a small amount of water to the solution was essential for the decomposition of cellulose. [Amim]Cl was stable against the discharge, as determined from the NMR signals measured before and after the discharge.

  18. Application of neural networks in identification of various types of partial discharges in gas insulated substations

    NASA Astrophysics Data System (ADS)

    Kishore, K. K.; Adikesavulu, A. K.; Singh, B. P.; Eswaran, Kumar

    2000-03-01

    Gas Insulated substations (GIS) up to 500kV class have been widely accepted over conventional air insulated substation due to several advantages. However, the presence of floating metal particles and protrusions within the GIS at various locations could seriously affect the performance. The paper describes the method of detection of partial discharges for various type of discharging sources e.g. floating particles, protrusions of high voltage conductor and particles sticking on the surface of insulator. In order to identify the discharge source, a Neural Network program is developed to classify each of the above source on the basis of its characteristic pattern.

  19. Effects of Gas Flow Rate on the Discharge Characteristics of a DC Excited Plasma Jet

    NASA Astrophysics Data System (ADS)

    Li, Xuechen; Jia, Pengying; Di, Cong; Bao, Wenting; Zhang, Chunyan

    2015-09-01

    A direct current (DC) source excited plasma jet consisting of a hollow needle anode and a plate cathode has been developed to form a diffuse discharge plume in ambient air with flowing argon as the working gas. Using optical and electrical methods, the discharge characteristics are investigated for the diffuse plasma plume. Results indicate that the discharge has a pulse characteristic, under the excitation of a DC voltage. The discharge pulse corresponds to the propagation process of a plasma bullet travelling from the anode to the cathode. It is found that, with an increment of the gas flow rate, both the discharge plume length and the current peak value of the pulsed discharge decrease in the laminar flow mode, reach their minima at about 1.5 L/min, and then slightly increase in the turbulent mode. However, the frequency of the pulsed discharge increases in the laminar mode with increasing the argon flow rate until the argon flow rate equals to about 1.5 L/min, and then slightly decreases in the turbulent mode. supported by National Natural Science Foundation of China (Nos. 10805013, 11375051), Funds for Distinguished Young Scientists of Hebei Province, China (No. A2012201045), Department of Education for Outstanding Youth Project of China (No. Y2011120), and Youth Project of Hebei University of China (No. 2011Q14)

  20. Treatment of Dye Wastewater by Using a Hybrid Gas/Liquid Pulsed Discharge Plasma Reactor

    NASA Astrophysics Data System (ADS)

    Lu, Na; Li, Jie; Wu, Yan; Masayuki, Sato

    2012-02-01

    A hybrid gas/liquid pulsed discharge plasma reactor using a porous ceramic tube is proposed for dye wastewater treatment. High voltage pulsed discharge plasma was generated in the gas phase and simultaneously the plasma channel was permeated through the tiny holes of the ceramic tube into the water phase accompanied by gas bubbles. The porous ceramic tube not only separated the gas phase and liquid phase but also offered an effective plasma spreading channel. The effects of the peak pulse voltage, additive gas varieties, gas bubbling rate, solution conductivity and TiO2 addition were investigated. The results showed that this reactor was effective for dye wastewater treatment. The decoloration efficiency of Acid Orange II was enhanced with an increase in the power supplied. Under the studied conditions, 97% of Acid Orange II in aqueous solution was effectively decolored with additive oxygen gas, which was 51% higher than that with argon gas, and the increasing O2 bubbling rate also benefited the decoloration of dye wastewater. Water conductivity had a small effect on the level of decoloration. Catalysis of TiO2 could be induced by the pulsed discharge plasma and addition of TiO2 aided the decoloration of Acid Orange II.

  1. Scheduling hydro power systems with restricted operating zones and discharge ramping constraints

    SciTech Connect

    Guan, X.; Svoboda, Al; Li, C.

    1999-02-01

    An optimization-based algorithm is presented for scheduling hydro power systems with restricted operating zones and discharge ramping constraints. Hydro watershed scheduling problems are difficult to solve because many constraints, continuous and discrete, including hydraulic coupling of cascaded reservoirs have to be considered. Restricted or forbidden operating zones as well as minimum generation limits of hydro units result in discontinuous preferred operating regions, and hinder direct applications of efficient continuous optimization methods such as network flow algorithms. Discharge ramping constraints due to navigational, environmental and recreational requirements in a hydro system add another dimension of difficulty since they couple generation or water discharge across time horizon. The key idea of this paper is to use additional sets of multipliers to relax discontinuous operating region and discharge ramping constraints on individual hydro units so that a two-level optimization structure is formed. The low level consists of a continuous discharge scheduling subproblem determining the generation levels of all units in the entire watershed, and a number of pure integer scheduling subproblems determining the hydro operating states, one for each unit. The discharge subproblem is solved by a network flow algorithm, and the integer scheduling problems are solved by dynamic programming with a small number of states and well-structured transitions. The two sets of subproblems are coordinated through multipliers updated at the high level by using a modified subgradient algorithm. After the dual problem converges, a feasible hydro schedule is obtained by using the same network flow algorithm with the operating states obtained, and operating ranges modified to guarantee satisfaction of ramping constraints.

  2. Mass spectrometric investigation of the ionic species in a dielectric barrier discharge operating in helium-water vapour mixtures

    NASA Astrophysics Data System (ADS)

    Abd-Allah, Z.; Sawtell, D. A. G.; McKay, K.; West, G. T.; Kelly, P. J.; Bradley, J. W.

    2015-03-01

    Using advanced mass spectrometry the chemistry of ionic species present in an atmospheric-pressure parallel plate dielectric barrier discharge (DBD) with a single dielectric on the powered electrode have been identified. The discharge was driven in helium with controllable concentrations of water vapour using an excitation frequency of 10 kHz and an applied voltage of 1.2 kV. Both negative and positive ions were identified and their relative intensity determined with variation of water concentration in the discharge, inter-electrode spacing, gas residence time and nominal applied power. The most abundant negative ions were of the family \\text{O}{{\\text{H}}-}{{≤ft({{\\text{H}}2}\\text{O}\\right)}n} , while the positive ions were dominated by those of the form {{{H}}^ + }{{{(}}{{{H}}_2}{{O)}}_n} , with n up to 9 in both cases. Negative and positive ions responded in a similar way to changes in the operating parameters, with the particular response depending on the ion mass. Increasing the inter-electrode spacing and the water concentration in the discharge led to an increase in the intensity of large mass ionic water clusters. However, increasing the residence time of the species in the plasma region and increasing the applied power resulted in fragmentation of large water clusters to produce smaller ions.

  3. Ring-shaped electric discharge as an igniter of gas mixtures

    NASA Astrophysics Data System (ADS)

    Barkhudarov, E. M.; Berezhetskaya, N. K.; Kop'ev, V. A.; Kossyi, I. A.; Popov, N. A.; Taktakishvili, M. I.; Temchin, S. M.

    2010-09-01

    Results are presented from experimental studies of ignition of a stoichiometric methane-oxygen mixture in a closed chamber by a ring electric discharge. It is shown that the process of fast (explosive) ignition of the reactor volume starts on the axis of the ring, near its centre, i.e. at a distance from the annular region of power deposition. Experimental evidence suggests that the ignition of a combustible gas mixture near the axis is triggered by strong gas-dynamic perturbations converging to the axis, radially propagating from the ring discharger.

  4. Binary and ternary gas mixtures for use in glow discharge closing switches

    DOEpatents

    Hunter, S.R.; Christophorou, L.G.

    1988-04-27

    Highly efficient binary and ternary gas mixtures for use in diffuse glow discharge closing switches are disclosed. The binary mixtures are combinations of helium or neon and selected perfluorides. The ternary mixtures are combinations of helium, neon, or argon, a selected perfluoride, and a small amount of gas that exhibits enhanced ionization characteristics. These mixtures are shown to be the optimum choices for use in diffuse glow discharge closing switches by virtue if the combines physio-electric properties of the mixture components. 9 figs.

  5. Method for visualizing gas temperature distributions around hypersonic vehicles by using electric discharge

    NASA Astrophysics Data System (ADS)

    Nishio, Masatomi

    1993-06-01

    A method for visualizing qualitative gas temperature distributions around hypersonic vehicles by taking a photograph of the electric discharge is proposed. A gas temperature distribution over a slightly blunted wedge is visualized using the electric discharge generated by a pair of point-line electrodes. A hypersonic tunnel used for the experiment is characterized by Mach 10, a freestream duration of 10 ms, and a stagnation temperature of the tunnel barrel of 1000 K. It is concluded that the photograph shows a radiation spectrum contrast near the model surface, from which a temperature layer is seen.

  6. Employing partially coherent, compact gas-discharge sources for coherent diffractive imaging with extreme ultraviolet light

    NASA Astrophysics Data System (ADS)

    Bußmann, J.; Odstrčil, M.; Bresenitz, R.; Rudolf, D.; Miao, Jianwei; Brocklesby, W. S.; Grützmacher, D.; Juschkin, L.

    2015-09-01

    Coherent diffractive imaging (CDI) and related techniques enable a new type of diffraction-limited high-resolution extreme ultraviolet (EUV) microscopy. Here, we demonstrate CDI reconstruction of a complex valued object under illumination by a compact gas-discharge EUV light source emitting at 17.3 nm (O VI spectral line). The image reconstruction method accounts for the partial spatial coherence of the radiation and allows imaging even with residual background light. These results are a first step towards laboratory-scale CDI with a gas-discharge light source for applications including mask inspection for EUV lithography, metrology and astronomy.

  7. Miniaturized Argon Plasma: Neutral Gas Characteristics in Dielectric Barrier Discharge

    NASA Astrophysics Data System (ADS)

    Ashraf, Farahat

    2015-10-01

    Plasma-neutral gas dynamics is computationally investigated in a miniaturized microthruster that encloses Ar and contains dielectric material sandwiched between two metal plates using a two-dimensional plasma mode. Spatial and temporal plasma properties are investigated by solving the Poisson equation with the conservation equations of charged and excited neutral plasma species using the COMSOL Multiphysics 4.2b. The microthruster property is found to depend on the secondary electron emission coefficient. The electrohydrodynamic force (EHD) is calculated and found to be significant in the sheath area near the dielectric layer and is found to affect gas flow dynamics including the Ar excimer formation and density. The effects of pressure and secondary emission coefficient are discussed. The plasma characteristics are affected by small changes in the secondary electron emission coefficient, which could result from the dielectric erosion and aging, and is found to affect the electrohydrodynamic force produced when the microthruster is used to produce thrust for a small spacecraft.

  8. ZnO Nanowire-Based Corona Discharge Devices Operated Under Hundreds of Volts

    NASA Astrophysics Data System (ADS)

    Yang, Wenming; Zhu, Rong; Zong, Xianli

    2016-02-01

    Minimizing the voltage of corona discharges, especially when using nanomaterials, has been of great interest in the past decade or so. In this paper, we report a new corona discharge device by using ZnO nanowires operated in atmospheric air to realize continuous corona discharge excited by hundreds of volts. ZnO nanowires were synthesized on microelectrodes using electric-field-assisted wet chemical method, and a thin tungsten film was deposited on the microchip to enhance discharging performance. The testing results showed that the corona inception voltages were minimized greatly by using nanowires compared to conventional dischargers as a result of the local field enhancement of nanowires. The corona could be continuously generated and self-sustaining. It was proved that the law of corona inception voltage obeyed the conventional Peek's breakdown criterion. An optimal thickness of tungsten film coated over ZnO nanowires was figured out to obtain the lowest corona inception voltage. The ion concentration of the nanowire-based discharger attained 1017/m3 orders of magnitude, which is practicable for most discharging applications.

  9. ZnO Nanowire-Based Corona Discharge Devices Operated Under Hundreds of Volts.

    PubMed

    Yang, Wenming; Zhu, Rong; Zong, Xianli

    2016-12-01

    Minimizing the voltage of corona discharges, especially when using nanomaterials, has been of great interest in the past decade or so. In this paper, we report a new corona discharge device by using ZnO nanowires operated in atmospheric air to realize continuous corona discharge excited by hundreds of volts. ZnO nanowires were synthesized on microelectrodes using electric-field-assisted wet chemical method, and a thin tungsten film was deposited on the microchip to enhance discharging performance. The testing results showed that the corona inception voltages were minimized greatly by using nanowires compared to conventional dischargers as a result of the local field enhancement of nanowires. The corona could be continuously generated and self-sustaining. It was proved that the law of corona inception voltage obeyed the conventional Peek's breakdown criterion. An optimal thickness of tungsten film coated over ZnO nanowires was figured out to obtain the lowest corona inception voltage. The ion concentration of the nanowire-based discharger attained 10(17)/m(3) orders of magnitude, which is practicable for most discharging applications. PMID:26880727

  10. Observation of charge separation and gas discharge during sliding friction between metals and insulators

    NASA Astrophysics Data System (ADS)

    Miura, T.

    2015-10-01

    Charge generation due to friction between stainless steel and fused quartz in a vacuum was measured, and it was found that the density of the charge separation at the friction contact was 4×10-4 C/m2 In experiments in ambient gas, reduction of the separated charge caused by microgap gas discharge was observed. The residual rate of the charge, which is the ratio of charge accumulation in an ambient gas to that in a vacuum, in argon ambient gas was small, and it seemed to be effective for the relaxation of generated static electricity due to friction between solids.

  11. Experimental investigation of a capacitive blind hollow cathode discharge with central gas injection

    NASA Astrophysics Data System (ADS)

    Hoffmann, D.; Müller, M.; Petkow, D.; Herdrich, G.; Lein, S.

    2014-12-01

    The operating parameters and resulting plasma properties of a blind hollow cathode (BHC) discharge have been investigated. The hollow cathode was driven capacitively with a pulsed dc signal of 200 kHz in a power range between 50 and 100 W at an ambient pressure of about 10 Pa. The working gas was argon, which was introduced with a ceramic capillary at different positions of the longitudinal axis of the hollow cathode with flow rates of between 30 and 1000 sccm. The current-voltage characteristics were recorded. The pressure at the end of the BHC was measured with a miniaturized pressure transducer with varying volumetric flow rate and axial position of the capillary in the hollow cathode. To characterize the ignition behaviour of the system, the measured breakdown voltages were compared with phenomenological Paschen curves calculated from the pressure data. Optical emission spectroscopy was used to examine the origins of the light emission, comparing the glow mode and hollow cathode mode in particular. A high-speed camera recorded some plasma processes. A mounting with an indium tin oxide coated glass was used to observe the inner volume of the BHC along the longitudinal axis, while the plasma was operated with different parameters. The optical observations revealed an inhomogeneous plasma condition along the axis.

  12. Discharge product morphology versus operating temperature in non-aqueous lithium-air batteries

    NASA Astrophysics Data System (ADS)

    Tan, P.; Shyy, W.; Zhao, T. S.; Wei, Z. H.; An, L.

    2015-03-01

    During the discharge process of non-aqueous lithium-air batteries, a solid product, Li2O2, forms in the pores of the porous cathode, and eventually causes the discharge process to cease. During the charge process, solid Li2O2 needs to be electrochemically oxidized. The morphology of the discharge product is, therefore, critically related to the capacity and reversibility of the battery. In this work, we experimentally show that for a given design of the cathode, the shape of the discharge product Li2O2 at a given discharge current density remains almost unchanged with a change in the operating temperature, but the size decreases with an increase in the temperature. We also demonstrate that the product shape varies with the discharge current density at a given temperature. The practical implication of these findings is that the capacity, charge voltage, and cyclability of a given non-aqueous lithium-air battery are affected by the operating temperature.

  13. Degradation of dyes by active species injected from a gas phase surface discharge

    NASA Astrophysics Data System (ADS)

    Li, Jie; Wang, Tiecheng; Lu, Na; Zhang, Dandan; Wu, Yan; Wang, Tianwei; Sato, Masayuki

    2011-06-01

    A reactor, based on the traditional gas phase surface discharge (GPSD), is designed for degradation of dye wastewater in this study. The reactor is characterized by using the dye wastewater as a ground electrode. A spiral discharge electrode of stainless steel wire attached on the inside wall of a cylindrical insulating medium and the wastewater surrounding the insulating medium for simultaneous cooling of the discharge electrode constitute the reactor. The active chemical radicals generated by the discharge of the spiral electrode are injected into the water with the carrier gas. The removal of three organic dyes (including methyl red (MR), reactive brilliant blue (RBB) and cationic red (CR)) in aqueous solution is investigated. The effects of electrode configuration, discharge voltage and solution pH value on the decoloration efficiency of MR are discussed. The experimental results show that over 95% of decoloration efficiencies for all the dyes are obtained after several minutes of plasma treatment. 40% of chemical oxygen demand removal of MR is obtained after 8 min of discharge treatment. Furthermore, it is found that ozone mainly affects the removal of dyes and several aliphatic compounds are identified as the oxidation products of MR. The possible degradation pathways of MR by GPSD are proposed.

  14. CORONA DISCHARGE IGNITION FOR ADVANCED STATIONARY NATURAL GAS ENGINES

    SciTech Connect

    Dr. Paul D. Ronney

    2003-09-12

    An ignition source was constructed that is capable of producing a pulsed corona discharge for the purpose of igniting mixtures in a test chamber. This corona generator is adaptable for use as the ignition source for one cylinder on a test engine. The first tests were performed in a cylindrical shaped chamber to study the characteristics of the corona and analyze various electrode geometries. Next a test chamber was constructed that closely represented the dimensions of the combustion chamber of the test engine at USC. Combustion tests were performed in this chamber and various electrode diameters and geometries were tested. The data acquisition and control system hardware for the USC engine lab was updated with new equipment. New software was also developed to perform the engine control and data acquisition functions. Work is underway to design a corona electrode that will fit in the new test engine and be capable igniting the mixture in one cylinder at first and eventually in all four cylinders. A test engine was purchased for the project that has two spark plug ports per cylinder. With this configuration it will be possible to switch between corona ignition and conventional spark plug ignition without making any mechanical modifications.

  15. A powerful electrohydrodynamic flow generated by a high-frequency dielectric barrier discharge in a gas

    NASA Astrophysics Data System (ADS)

    Nebogatkin, S. V.; Rebrov, I. E.; Khomich, V. Yu.; Yamshchikov, V. A.

    2016-01-01

    Theoretical and experimental studies of an electrohydrodynamic flow induced by a high-frequency dielectric barrier discharge distributed over a dielectric surface in a gas have been conducted. Dependences of the ion current, the gas flow velocity, and the spatial distributions thereof on the parameters of the power supply of the plasma ion emitter and an external electric field determined by the collector grid voltage have been described.

  16. Discharge characteristics and hydrodynamics behaviors of atmospheric plasma jets produced in various gas flow patterns

    NASA Astrophysics Data System (ADS)

    Setsuhara, Yuichi; Uchida, Giichiro; Nakajima, Atsushi; Takenaka, Kosuke; Koga, Kazunori; Shiratani, Masaharu

    2015-09-01

    Atmospheric nonequilibrium plasma jets have been widely employed in biomedical applications. For biomedical applications, it is an important issue to understand the complicated mechanism of interaction of the plasma jet with liquid. In this study, we present analysis of the discharge characteristics of a plasma jet impinging onto the liquid surface under various gas flow patterns such as laminar and turbulence flows. For this purpose, we analyzed gas flow patters by using a Schlieren gas-flow imaging system in detail The plasma jet impinging into the liquid surface expands along the liquid surface. The diameter of the expanded plasma increases with gas flow rate, which is well explained by an increase in the diameter of the laminar gas-flow channel. When the gas flow rate is further increased, the gas flow mode transits from laminar to turbulence in the gas flow channel, which leads to the shortening of the plasm-jet length. Our experiment demonstrated that the gas flow patterns strongly affect the discharge characteristics in the plasma-jet system. This study was partly supported by a Grant-in-Aid for Scientific Research on Innovative Areas ``Plasma Medical Innovation'' (24108003) from the Ministry of Education, Culture, Sports, Science and Technology, Japan (MEXT).

  17. Characterization of a radio frequency hollow electrode discharge at low gas pressures

    NASA Astrophysics Data System (ADS)

    Ahadi, Amir Mohammad; Trottenberg, Thomas; Rehders, Stefan; Strunskus, Thomas; Kersten, Holger; Faupel, Franz

    2015-08-01

    A radio frequency (RF) hollow discharge configuration is presented, which makes use of a combination of RF plasma generation and the hollow cathode effect. The system was especially designed for the treatment of nanoparticles, plasma polymerization, and nanocomposite fabrication. The process gas streams through the plasma in the inner of the cylindrical electrode system. In the here presented measurements, pure argon and argon with oxygen admixtures are exemplarily used. The discharge is characterized by probe measurements in the effluent, electrical measurements of the discharge parameters, and visual observations of the plasma glow. It is found that the RF fluctuations of the plasma potential are weak. The plasma potential resembles the one of a DC hollow cathode discharge, the RF hollow electrode acts as a cathode due to the self-bias, and a high voltage sheath forms in its inner cylinder.

  18. Three-dimensional numerical modelling of gas discharges at atmospheric pressure incorporating photoionization phenomena

    NASA Astrophysics Data System (ADS)

    Papageorgiou, L.; Metaxas, A. C.; Georghiou, G. E.

    2011-02-01

    A three-dimensional (3D) numerical model for the characterization of gas discharges in air at atmospheric pressure incorporating photoionization through the solution of the Helmholtz equation is presented. Initially, comparisons with a two-dimensional (2D) axi-symmetric model are performed in order to assess the validity of the model. Subsequently several discharge instabilities (plasma spots and low pressure inhomogeneities) are considered in order to study their effect on streamer branching and off-axis propagation. Depending on the magnitude and position of the plasma spot, deformations and off-axis propagation of the main discharge channel were obtained. No tendency for branching in small (of the order of 0.1 cm) overvolted discharge gaps was observed.

  19. Characterization of a radio frequency hollow electrode discharge at low gas pressures

    SciTech Connect

    Ahadi, Amir Mohammad; Rehders, Stefan; Strunskus, Thomas; Faupel, Franz; Trottenberg, Thomas; Kersten, Holger

    2015-08-15

    A radio frequency (RF) hollow discharge configuration is presented, which makes use of a combination of RF plasma generation and the hollow cathode effect. The system was especially designed for the treatment of nanoparticles, plasma polymerization, and nanocomposite fabrication. The process gas streams through the plasma in the inner of the cylindrical electrode system. In the here presented measurements, pure argon and argon with oxygen admixtures are exemplarily used. The discharge is characterized by probe measurements in the effluent, electrical measurements of the discharge parameters, and visual observations of the plasma glow. It is found that the RF fluctuations of the plasma potential are weak. The plasma potential resembles the one of a DC hollow cathode discharge, the RF hollow electrode acts as a cathode due to the self-bias, and a high voltage sheath forms in its inner cylinder.

  20. Waveguide CO2 laser gain: Dependence on gas kinetic and discharge properties

    NASA Technical Reports Server (NTRS)

    Cohen, S. C.

    1975-01-01

    Using a simple rate equation approach the gas kinetic and discharge properties of waveguide CO2 lasers were examined. The dependence was calculated of the population inversion and laser small signal gain on gas pressure, gas mixture, pumping rate (discharge current), tube bore diameter, and wall temperature. At higher pressures the gain is optimized by using more helium rich mixtures and smaller bore diameters. The dependence of laser tunability on the gas kinetic properties and cavity losses was determined, it was found that for loss cavities the laser tunability may substantially exceed the molecular fullwidth at half maximum. The more helium rich gas mixtures give greater tunability when cavity losses are small and less tunability when cavity losses are large. The role of the various gases in the waveguide CO2 laser is the same as that in conventional devices, by contrast with conventional lasers, the waveguide laser transition is homogeneously broadened. The dependence of gain on gas pressure and other kinetic and discharge properties differs substantially from that predicted by scaling results from conventional low pressure lasers.

  1. Influence of dust-particle concentration on gas-discharge plasma

    SciTech Connect

    Sukhinin, G. I.; Fedoseev, A. V.

    2010-01-15

    A self-consistent kinetic model of a low-pressure dc glow discharge with dust particles based on Boltzmann equation for the electron energy distribution function is presented. The ions and electrons production in ionizing processes as well as their recombination on the dust-particle surface and on the discharge tube wall were taken into account. The influence of dust-particle concentration N{sub d} on gas discharge and dust particles parameters was investigated. It is shown that the increase of N{sub d} leads to the increase of an averaged electric field and ion density, and to the decrease of a dust-particle charge and electron density in the dusty cloud. The results were obtained in a wide region of different discharge and dusty plasma parameters: dust particles density 10{sup 2}-10{sup 8} cm{sup -3}, discharge current density 10{sup -1}-10{sup 1} mA/cm{sup 2}, and dust particles radius 1, 2, and 5 mum. The scaling laws for dust-particle surface potential and electric filed dependencies on dust-particle density, particle radius and discharge currents were revealed. It is shown that the absorption of electrons and ions on the dust particles surface does not lead to the electron energy distribution function depletion due to a self-consistent adjustment of dust particles and discharge parameters.

  2. Ignition of a combustible gas mixture by a high-current electric discharge in a closed volume

    SciTech Connect

    Berezhetskaya, N. K.; Gritsinin, S. I.; Kop'ev, V. A.; Kossyi, I. A.; Kuleshov, P. S.; Popov, N. A.; Starik, A. M.; Tarasova, N. M.

    2009-06-15

    Results are presented from experimental studies and numerical calculations of the ignition of a stoichiometric CH{sub 4}: O{sub 2} gas mixture by a high-current gliding discharge. It is shown that this type of discharge generates an axially propagating thermal wave (precursor) that penetrates into the gas medium and leads to fast gas heating. This process is followed by an almost simultaneous ignition of the gas mixture over the entire reactor volume.

  3. Johann Wilhelm Hittorf and the material culture of nineteenth-century gas discharge research.

    PubMed

    Müller, Falk

    2011-06-01

    In the second half of the nineteenth century, gas discharge research was transformed from a playful and fragmented field into a new branch of physical science and technology. From the 1850s onwards, several technical innovations-powerful high-voltage supplies, the enhancement of glass-blowing skills, or the introduction of mercury air-pumps- allowed for a major extension of experimental practices and expansion of the phenomenological field. Gas discharge tubes served as containers in which resources from various disciplinary contexts could be brought together; along with the experimental apparatus built around them the tubes developed into increasingly complex interfaces mediating between the human senses and the micro-world. The focus of the following paper will be on the physicist and chemist Johann Wilhelm Hittorf (1824-1914), his educational background and his attempts to understand gaseous conduction as a process of interaction between electrical energy and matter. Hittorf started a long-term project in gas discharge research in the early 1860s. In his research he tried to combine a morphological exploration of gas discharge phenomena-aiming at the experimental production of a coherent phenomenological manifold--with the definition and precise measurements of physical properties. PMID:21879606

  4. 21 CFR 1020.20 - Cold-cathode gas discharge tubes.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... as specified herein. (b) Definitions. Beam blocking device means a movable or removable portion of... prevent the emergence of an exit beam. Cold-cathode gas discharge tube means an electronic device in which... cathode. Exit beam means that portion of the radiation which passes through the aperture resulting...

  5. Characteristics of atmospheric-pressure, radio-frequency glow discharges operated with argon added ethanol

    SciTech Connect

    Sun Wenting; Li Guo; Li Heping; Bao Chengyu; Wang Huabo; Zeng Shi; Gao Xing; Luo Huiying

    2007-06-15

    Rf, atmospheric-pressure glow discharge (APGD) plasmas with bare metal electrodes have promising prospects in the fields of plasma-aided etching, thin film deposition, disinfection and sterilization, etc. In this paper, the discharge characteristics are presented for the rf APGD plasmas generated with pure argon or argon-ethanol mixture as the plasma-forming gas and using water-cooled, bare copper electrodes. The experimental results show that the breakdown voltage can be reduced significantly when a small amount of ethanol is added into argon, probably due to the fact that the Penning ionization process is involved, and a pure {alpha}-mode discharge can be produced more easily with the help of ethanol. The uniformity of the rf APGDs of pure argon or argon-ethanol mixtures using bare metallic electrodes is identified with the aid of the intensified charge coupled device images.

  6. Characteristics of atmospheric-pressure, radio-frequency glow discharges operated with argon added ethanol

    NASA Astrophysics Data System (ADS)

    Sun, Wen-Ting; Li, Guo; Li, He-Ping; Bao, Cheng-Yu; Wang, Hua-Bo; Zeng, Shi; Gao, Xing; Luo, Hui-Ying

    2007-06-01

    Rf, atmospheric-pressure glow discharge (APGD) plasmas with bare metal electrodes have promising prospects in the fields of plasma-aided etching, thin film deposition, disinfection and sterilization, etc. In this paper, the discharge characteristics are presented for the rf APGD plasmas generated with pure argon or argon-ethanol mixture as the plasma-forming gas and using water-cooled, bare copper electrodes. The experimental results show that the breakdown voltage can be reduced significantly when a small amount of ethanol is added into argon, probably due to the fact that the Penning ionization process is involved, and a pure α-mode discharge can be produced more easily with the help of ethanol. The uniformity of the rf APGDs of pure argon or argon-ethanol mixtures using bare metallic electrodes is identified with the aid of the intensified charge coupled device images.

  7. Use of GTE-65 gas turbine power units in the thermal configuration of steam-gas systems for the refitting of operating thermal electric power plants

    SciTech Connect

    Lebedev, A. S.; Kovalevskii, V. P.; Getmanov, E. A.; Ermaikina, N. A.

    2008-07-15

    Thermal configurations for condensation, district heating, and discharge steam-gas systems (PGU) based on the GTE-65 gas turbine power unit are described. A comparative multivariant analysis of their thermodynamic efficiency is made. Based on some representative examples, it is shown that steam-gas systems with the GTE-65 and boiler-utilizer units can be effectively used and installed in existing main buildings during technical refitting of operating thermal electric power plants.

  8. Ozone generation in a kHz-pulsed He-O2 capillary dielectric barrier discharge operated in ambient air

    NASA Astrophysics Data System (ADS)

    Sands, Brian L.; Ganguly, Biswa N.

    2013-12-01

    The generation of reactive oxygen species using nonequilibrium atmospheric pressure plasma jet devices has been a subject of recent interest due to their ability to generate localized concentrations from a compact source. To date, such studies with plasma jet devices have primarily utilized radio-frequency excitation. In this work, we characterize ozone generation in a kHz-pulsed capillary dielectric barrier discharge configuration comprised of an active discharge plasma jet operating in ambient air that is externally grounded. The plasma jet flow gas was composed of helium with an admixture of up to 5% oxygen. A unipolar voltage pulse train with a 20 ns pulse risetime was used to drive the discharge at repetition rates between 2-25 kHz. Using UVLED absorption spectroscopy centered at 255 nm near the Hartley-band absorption peak, ozone was detected over 1 cm from the capillary axis. We observed roughly linear scaling of ozone production with increasing pulse repetition rate up to a "turnover frequency," beyond which ozone production steadily dropped and discharge current and 777 nm O(5P→5S°) emission sharply increased. The turnover in ozone production occurred at higher pulse frequencies with increasing flow rate and decreasing applied voltage with a common energy density of 55 mJ/cm3 supplied to the discharge. The limiting energy density and peak ozone production both increased with increasing O2 admixture. The power dissipated in the discharge was obtained from circuit current and voltage measurements using a modified parallel plate dielectric barrier discharge circuit model and the volume-averaged ozone concentration was derived from a 2D ozone absorption measurement. From these measurements, the volume-averaged efficiency of ozone production was calculated to be 23 g/kWh at conditions for peak ozone production of 41 mg/h at 11 kV applied voltage, 3% O2, 2 l/min flow rate, and 13 kHz pulse repetition rate, with 1.79 W dissipated in the discharge.

  9. Plasma Discharges in Gas Bubbles in Liquid Water: Breakdown Mechanisms and Resultant Chemistry

    NASA Astrophysics Data System (ADS)

    Gucker, Sarah M. N.

    The use of atmospheric pressure plasmas in gases and liquids for purification of liquids has been investigated by numerous researchers, and is highly attractive due to their strong potential as a disinfectant and sterilizer. However, the fundamental understanding of plasma production in liquid water is still limited. Despite the decades of study dedicated to electrical discharges in liquids, many physical aspects of liquids, such as the high inhomogeneity of liquids, complicate analyses. For example, the complex nonlinearities of the fluid have intricate effects on the electric field of the propagating streamer. Additionally, the liquid material itself can vaporize, leading to discontinuous liquid-vapor boundaries. Both can and do often lead to notable hydrodynamic effects. The chemistry of these high voltage discharges on liquid media can have circular effects, with the produced species having influence on future discharges. Two notable examples include an increase in liquid conductivity via charged species production, which affects the discharge. A second, more complicated scenario seen in some liquids (such as water) is the doubling or tripling of molecular density for a few molecule layers around a high voltage electrode. These complexities require technological advancements in optical diagnostics that have only recently come into being. This dissertation investigates several aspects of electrical discharges in gas bubbles in liquids. Two primary experimental configurations are investigated: the first allows for single bubble analysis through the use of an acoustic trap. Electrodes may be brought in around the bubble to allow for plasma formation without physically touching the bubble. The second experiment investigates the resulting liquid phase chemistry that is driven by the discharge. This is done through a dielectric barrier discharge with a central high voltage surrounded by a quartz discharge tube with a coil ground electrode on the outside. The plasma

  10. 20 CFR 726.207 - Discharge by the carrier of obligations and duties of operator.

    Code of Federal Regulations, 2014 CFR

    2014-04-01

    ... 20 Employees' Benefits 4 2014-04-01 2014-04-01 false Discharge by the carrier of obligations and duties of operator. 726.207 Section 726.207 Employees' Benefits OFFICE OF WORKERS' COMPENSATION PROGRAMS, DEPARTMENT OF LABOR FEDERAL COAL MINE HEALTH AND SAFETY ACT OF 1969, AS AMENDED BLACK LUNG...

  11. 20 CFR 726.207 - Discharge by the carrier of obligations and duties of operator.

    Code of Federal Regulations, 2013 CFR

    2013-04-01

    ... 20 Employees' Benefits 4 2013-04-01 2013-04-01 false Discharge by the carrier of obligations and duties of operator. 726.207 Section 726.207 Employees' Benefits OFFICE OF WORKERS' COMPENSATION PROGRAMS, DEPARTMENT OF LABOR FEDERAL COAL MINE HEALTH AND SAFETY ACT OF 1969, AS AMENDED BLACK LUNG...

  12. 20 CFR 726.207 - Discharge by the carrier of obligations and duties of operator.

    Code of Federal Regulations, 2012 CFR

    2012-04-01

    ... 20 Employees' Benefits 4 2012-04-01 2012-04-01 false Discharge by the carrier of obligations and duties of operator. 726.207 Section 726.207 Employees' Benefits OFFICE OF WORKERS' COMPENSATION PROGRAMS, DEPARTMENT OF LABOR FEDERAL COAL MINE HEALTH AND SAFETY ACT OF 1969, AS AMENDED BLACK LUNG...

  13. 33 CFR 151.69 - Operating requirements: Discharge of garbage outside special areas.

    Code of Federal Regulations, 2012 CFR

    2012-07-01

    ... 33 Navigation and Navigable Waters 2 2012-07-01 2012-07-01 false Operating requirements: Discharge of garbage outside special areas. 151.69 Section 151.69 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION VESSELS CARRYING OIL, NOXIOUS LIQUID SUBSTANCES, GARBAGE, MUNICIPAL OR COMMERCIAL WASTE,...

  14. 33 CFR 151.69 - Operating requirements: Discharge of garbage outside special areas.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Operating requirements: Discharge of garbage outside special areas. 151.69 Section 151.69 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION VESSELS CARRYING OIL, NOXIOUS LIQUID SUBSTANCES, GARBAGE, MUNICIPAL OR COMMERCIAL WASTE,...

  15. 33 CFR 151.73 - Operating requirements: Discharge of garbage from fixed or floating platforms.

    Code of Federal Regulations, 2014 CFR

    2014-07-01

    ... 33 Navigation and Navigable Waters 2 2014-07-01 2014-07-01 false Operating requirements: Discharge of garbage from fixed or floating platforms. 151.73 Section 151.73 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION VESSELS CARRYING OIL, NOXIOUS LIQUID SUBSTANCES, GARBAGE, MUNICIPAL OR...

  16. 33 CFR 151.71 - Operating requirements: Discharge of garbage within special areas.

    Code of Federal Regulations, 2011 CFR

    2011-07-01

    ... 33 Navigation and Navigable Waters 2 2011-07-01 2011-07-01 false Operating requirements: Discharge of garbage within special areas. 151.71 Section 151.71 Navigation and Navigable Waters COAST GUARD, DEPARTMENT OF HOMELAND SECURITY (CONTINUED) POLLUTION VESSELS CARRYING OIL, NOXIOUS LIQUID SUBSTANCES, GARBAGE, MUNICIPAL OR COMMERCIAL WASTE,...

  17. Binary and ternary gas mixtures with temperature enhanced diffuse glow discharge characteristics for use in closing switches

    DOEpatents

    Christophorou, Loucas G.; Hunter, Scott R.

    1990-01-01

    An improvement to the gas mixture used in diffuse glow discharge closing switches is disclosed which includes binary and ternary gas mixtures which are formulated to exhibit decreasing electron attachment with increasing temperature. This increases the efficiency of the conductance of the glow discharge and further inhibits the formation of an arc.

  18. Binary and ternary gas mixtures with temperature enhanced diffuse glow discharge characteristics for use in closing switches

    DOEpatents

    Christophorou, L.G.; Hunter, S.R.

    1988-06-28

    An improvement to the gas mixture used in diffuse glow discharge closing switches is disclosed which includes binary and ternary gas mixtures which are formulated to exhibit decreasing electron attachment with increasing temperature. This increases the efficiency of the conductance of the glow discharge and further inhibits the formation of an arc. 11 figs.

  19. Binary and ternary gas mixtures with temperature enhanced diffuse glow discharge characteristics for use in closing switches

    DOEpatents

    Christophorou, L.G.; Hunter, S.R.

    1990-06-26

    An improvement to the gas mixture used in diffuse glow discharge closing switches is disclosed which includes binary and ternary gas mixtures which are formulated to exhibit decreasing electron attachment with increasing temperature. This increases the efficiency of the conductance of the glow discharge and further inhibits the formation of an arc. 11 figs.

  20. Gas discharges in fumarolic ice caves of Erebus volcano, Antarctica

    NASA Astrophysics Data System (ADS)

    Fischer, T. P.; Curtis, A. G.; Kyle, P. R.; Sano, Y.

    2013-12-01

    Fumarolic ice caves and towers on Erebus are the surface expression of flank degassing on the world's southernmost active volcano. The caves are formed by warm gases and steam escaping from small vents on the lava flow floors that melts the overlying ice and snow. Extremophiles in the caves may be analogues for extraterrestrial environments. Over the past four Austral summers, mapping, gas and thermal monitoring conducted under the Erebus Caves Project has provided insights into the ice cave formation processes and the relationships between cave structures, magmatic processes, and weather. Gas samples were collected during the 2012 - 2013 field season in 4 ice caves (Warren, Harry's Dream, Sauna, Haggis Hole) as well as the thermal ground at Tramway Ridge. The vents at all of these sites are characterized by diffuse degassing through loose lava or cracks in the lava flow floor. Vent temperatures ranged from 5 to 17°C in most caves and at Tramway Ridge. In Sauna cave the temperature was 40°C. Gases were sampled by inserting a perforated 1 m long, 5 mm diameter stainless steel tube, into the vents or hot ground. Giggenbach bottles, copper tubes and lead glass bottles were connected in series. The gases were pumped at a slow rate (about 20 ml per minute) using a battery pump for 12-24 hours to flush the system. After flushing samples were collected for later analyses. All samples are dominated by atmospheric components, however, carbon dioxide (0.1 to 1.9%), methane (0.005 to 0.01%), hydrogen (0.002 to 0.07%), and helium (0.0009 to 0.002 %) are above air background. Nitrogen (average 74%) and oxygen (23.5%) are slightly below and above air values, respectively. Helium isotopes show minor input of mantle derived helium-3 with 3He4He ratios ranging from 1.03 to 1.18 RA (where RA is the ratio of air). This represents the first detection of hydrogen and helium in the caves. Methane could be produced by anaerobic respiration of subsurface microbes or hydrothermal

  1. High-power EUV lithography sources based on gas discharges and laser-produced plasmas

    NASA Astrophysics Data System (ADS)

    Stamm, Uwe; Ahmad, Imtiaz; Balogh, Istvan; Birner, H.; Bolshukhin, D.; Brudermann, J.; Enke, S.; Flohrer, Frank; G„bel, Kai; G÷tze, S.; Hergenhan, G.; Kleinschmidt, J.'rgen; Kl÷pfel, Diethard; Korobotchko, Vladimir; Ringling, Jens; Schriever, Guido; Tran, C. D.; Ziener, C.

    2003-06-01

    Semiconductor chip manufacturers are expecting to use extreme UV lithography for production in 2009. EUV tools require high power, brilliant light sources at 13.5 nm with collector optics producing 120 W average power at entrance of the illuminator system. Today the power and lifetime of the EUV light source are considered as the most critical issue for EUV lithography. The present paper gives an update of the development status of EUV light sources at XTREME technologies, a joint venture of Lambda Physik AG, Goettingen, and Jenoptik LOS GmbH, Jena, Germany. Results on both laser produced plasma (LPP) and gas discharge produced plasma (GDPP), the two major technologies in EUV sources, are given. The LPP EUV sources use xenon-jet target systems and pulsed lasers with 400 W average power at 10 kHz developed at XTREME technologies. The maximum conversion efficiency form laser power into EUV in-band power is 0.75% into 2π solid angle. With 300 W laser average power at 3300 Hz repetition rate up to 1.5 W EUV radiation is generated at 13.5 nm. After a collector of 5 sr this corresponds to 0.6 W in intermediate focus without spectral purity filter and 0.5 W in intermediate focus with spectral purity filter. The direct generation of the EUV emitting plasma from electrical discharges is much simpler than LPP because the electrical energy has not to be converted into laser radiation before plasma excitation. XTREME technologies' Xenon GDPP EUV sources use the Z-pinch principle with efficient sliding discharge pre-ionization. The plasma pinch size and the available emission angle have been matched to the etendue of the optical system of 2-3 mm2 sr, i.e. no additional etendue related loss reduces the usable EUV power from the source. In continuous operation at 1000 Hz the GDPP sources emit 50W into 2π solid angle are obtained from the Z-pinch sources. Spatial and temporal emission stability of the EUV sources is in the range of a few percent. Debris shields for EUV sources

  2. Low power gas discharge plasma mediated inactivation and removal of biofilms formed on biomaterials

    PubMed Central

    Traba, Christian; Chen, Long; Liang, Jun F.

    2013-01-01

    The antibacterial activity of gas discharge plasma has been studied for quiet some time. However, high biofilm inactivation activity of plasma was only recently reported. Studies indicate that the etching effect associated with plasmas generated represent an undesired effect, which may cause live bacteria relocation and thus contamination spreading. Meanwhile, the strong etching effects from these high power plasmas may also alter the surface chemistry and affect the biocompatibility of biomaterials. In this study, we examined the efficiency and effectiveness of low power gas discharge plasma for biofilm inactivation and removal. Among the three tested gases, oxygen, nitrogen, and argon, discharge oxygen demonstrated the best anti-biofilm activity because of its excellent ability in killing bacteria in biofilms and mild etching effects. Low power discharge oxygen completely killed and then removed the dead bacteria from attached surface but had negligible effects on the biocompatibility of materials. DNA left on the regenerated surface after removal of biofilms did not have any negative impact on tissue cell growth. On the contrary, dramatically increased growth was found for these cells seeded on regenerated surfaces. These results demonstrate the potential applications of low power discharge oxygen in biofilm treatments of biomaterials and indwelling device decontaminations. PMID:23894232

  3. Emission spectroscopy of a microhollow cathode discharge plasma in helium-water gas mixtures

    SciTech Connect

    Namba, S.; Yamasaki, T.; Hane, Y.; Fukuhara, D.; Kozue, K.; Takiyama, K.

    2011-10-01

    A dc microhollow cathode discharge (MHCD) plasma was generated inflowing helium gas containing water vapor. The cathode hole diameters were 0.3, 0.7, 1.0, and 2.0 mm, each with a length of 2.0 mm. Emission spectroscopy was carried out to investigate the discharge mode and to determine the plasma parameters. For the 0.3-mm cathode, stable MHCDs in an abnormal glow mode existed at pressures up to 100 kPa, whereas for larger diameters, a plasma was not generated at atmospheric pressure. An analysis of the lineshapes relevant to He at 667.8 nm and to H{alpha} at 656.3 nm implied an electron density and gas temperature of 2 x 10{sup 14} cm{sup -3} and 1100 K, respectively, for a 100-kPa discharge in the negative glow region. The dependence of the OH band, and H{alpha} intensities on the discharge current exhibited different behaviors. Specifically, the OH spectrum had a maximum intensity at a certain current, while the H atom intensity kept increasing with the discharge current. This observation implies that a high concentration of OH radicals results in quenching, leading to the production of H atoms via the reaction OH + e{sup -}{yields} O + H + e{sup -}.

  4. Research of the DC discharge of He-Ne gas mixture in hollow core fiber

    NASA Astrophysics Data System (ADS)

    Wang, Xinbing; Duan, Lian

    2013-09-01

    Since the first waveguide 0.633 μm He-Ne laser from a 20 cm length of 430 μm glass capillary was reported in 1971, no smaller waveguide gas laser has ever been constructed. Recently as the development of low loss hollow core PBG fiber, it is possible to constract a He-Ne lasers based on hollow-core PBG fibers. For the small diameter of the air hole, it is necessary to do some research to obtain glow discharge in hollow core fibers. In this paper, the experimental research of DC discharge in 200 μm bore diameter hollow core fibers was reported. Stable glow discharge was obained at varioue He-Ne mixtures from 4 Torr to 18 Torr. In order to obtain the plasma parameter of the discharge, the trace gasses of N2 and H2 were added to the He-Ne mixtures, the optical emission spectroscopy of the discharge was recorded by a PI 2750 spectroscopy with a CCD camera. The gas temperature (Tg) could be obtained by matching the simulated rovibronic band of the N2 emission with the observed spectrum in the ultraviolet region. The spectral method was also used to obtained the electron density, which is based on the analysis of the wavelength profile of the 486.13 nm Hβ line, and the electron temperature was obtain by Boltzmann plot methods. Experimental results show that it is very difficult to achieve DC discharge in bore diameter less than 50 μm, and a RF discharge method was proposed. Project supported by the National Natural Science Foundation of China (61078033).

  5. Size-controlled synthesis and gas sensing application of tungsten oxide nanostructures produced by arc discharge.

    PubMed

    Fang, F; Kennedy, J; Futter, J; Hopf, T; Markwitz, A; Manikandan, E; Henshaw, G

    2011-08-19

    Several different synthetic methods have been developed to fabricate tungsten oxide (WO(3)) nanostructures, but most of them require exotic reagents or are unsuitable for mass production. In this paper, we present a systematic investigation demonstrating that arc discharge is a fast and inexpensive synthesis method which can be used to produce high quality tungsten oxide nanostructures for NO(2) gas sensing measurements. The as-synthesized WO(3) nanostructures are characterized by x-ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), finger-print Raman spectroscopy and proton induced x-ray emission (PIXE). The analysis shows that spheroidal-shaped monoclinic WO(3) crystal nanostructures were produced with an average diameter of 30 nm (range 10-100 nm) at an arc discharge current of 110 A and 300 Torr oxygen partial pressure. It is found that the morphology is controlled by the arc discharge parameters of current and oxygen partial pressure, e.g. a high arc discharge current combined with a low oxygen partial pressure results in small WO(3) nanostructures with improved conductivity. Sensors produced from the WO(3) nanostructures show a strong response to NO(2) gas at 325 °C. The ability to tune the morphology of the WO(3) nanostructures makes this method ideal for the fabrication of gas sensing materials. PMID:21778569

  6. PREFACE: 12th International Conference on Gas Discharge Plasmas and Their Applications

    NASA Astrophysics Data System (ADS)

    Koval, N.; Landl, N.; Bogdan, A.; Yudin, A.

    2015-11-01

    The 12th International Conference ''Gas Discharge Plasmas and Their Applications'' (GDP 2015) was held in Tomsk, Russia, on September 6-11, 2015. GDP 2015 represents a continuation of the conferences on physics of gas discharge held in Russia since 1984 and seminars and conferences on the technological applications of low temperature plasmas traditionally organized in Tomsk. The six-day Conference brought together the specialists from different countries and organizations and provided an excellent opportunity to exchange knowledge, make oral contributions and poster presentations, and initiate discussions on the topics that are of interest to the Conference participants. The selected papers of the Conference cover a wide range of technical areas and modern aspects of the physical processes in the generators of low-temperature plasma, the low and high-pressure discharges, the pulsed plasma sources, the surface modification, and other gas-discharge technologies. The Conference was hosted by Institute of High Current Electronics SB RAS, Tomsk Polytechnic University, Tomsk Scientific Center, and Tomsk State University of Architecture and Building.

  7. Singlet oxygen generation in gas discharge for oxygen-iodine laser pumping

    NASA Astrophysics Data System (ADS)

    Lopaev, D. V.; Braginsky, O. V.; Klopovsky, K. S.; Kovalev, A. S.; Mankelevich, Yu. A.; Popov, N. A.; Rakhimov, A. T.; Rakhimova, T. V.; Vasilieva, A. N.

    2004-09-01

    The possibility of development of effective discharged singlet oxygen (SO) generator (DSOG) for oxygen-iodine laser (OIL) is studied in detail. Researches of kinetics of oxygen atoms and oxygen molecules in the lowest metastable singlet states have been carried out in the different discharges and its afterglow (DC discharges, E-beam controlled discharge and RF discharges) in both CW and pulsed mode in a wide range of conditions (pressures, gas mixtures, energy deposits etc.). The models developed for all the discharges have allowed us to analyze SO generation and loss mechanisms and to find out the key-parameters controlling the highest SO yield. It is shown that in addition to spatial plasma uniformity at low E/N and high specific energy deposit per oxygen molecule, DSOG must be oxygen atom free to avoid fast three-body quenching of SO by atomic oxygen with increasing pressure and thereby to provide pressure scaling (in tens Torrs) for applying to real OIL systems.

  8. Evaluation of the potentials of humic acid removal in water by gas phase surface discharge plasma.

    PubMed

    Wang, Tiecheng; Qu, Guangzhou; Ren, Jingyu; Yan, Qiuhe; Sun, Qiuhong; Liang, Dongli; Hu, Shibin

    2016-02-01

    Degradation of humic acid (HA), a predominant type of natural organic matter in ground water and surface waters, was conducted using a gas phase surface discharge plasma system. HA standard and two surface waters (Wetland, and Weihe River) were selected as the targets. The experimental results showed that about 90.9% of standard HA was smoothly removed within 40 min's discharge plasma treatment at discharge voltage 23.0 kV, and the removal process fitted the first-order kinetic model. Roles of some active species in HA removal were studied by evaluating the effects of solution pH and OH radical scavenger; and the results presented that O3 and OH radical played significant roles in HA removal. Scanning electron microscope (SEM) and FTIR analysis showed that HA surface topography and molecular structure were changed during discharge plasma process. The mineralization of HA was analyzed by UV-Vis spectrum, dissolved organic carbon (DOC), specific UV absorbance (SUVA), UV absorption ratios, and excitation-emission matrix (EEM) fluorescence. The formation of disinfection by-products during HA sample chlorination was also identified, and CHCl3 was detected as the main disinfection by-product, but discharge plasma treatment could suppress its formation to a certain extent. In addition, approximately 82.3% and 67.9% of UV254 were removed for the Weihe River water and the Wetland water after 40 min of discharge plasma treatment. PMID:26624519

  9. LASER APPLICATIONS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Gas-dynamic effects in the interaction of a motionless optical pulsating discharge with gas

    NASA Astrophysics Data System (ADS)

    Tishchenko, V. N.; Grachev, G. N.; Pavlov, A. A.; Smirnov, A. L.; Pavlov, A. A.; Golubev, M. P.

    2008-01-01

    The effect of energy removal from the combustion zone of a motionless optical pulsating discharge in the horizontal direction along the axis of a repetitively pulsed laser beam producing the discharge is discovered. The directivity diagram of a hot gas flow is formed during the action of hundreds of pulses. The effect is observed for short pulse durations, when the discharge efficiently generates shock waves. For long pulse durations, the heated gas propagates upward, as in a thermal source.

  10. Gas laser for efficient sustaining a continuous optical discharge plasma in scientific and technological applications

    SciTech Connect

    Zimakov, V P; Kuznetsov, V A; Kedrov, A Yu; Solov'ev, N G; Shemyakin, A N; Yakimov, M Yu

    2009-09-30

    A stable high-power laser is developed for the study and technical applications of a continuous optical discharge (COD). The laser based on the technology of a combined discharge in a scheme with a fast axial gas flow emits 2.2 kW at 10.6 {mu}m per meter of the active medium in continuous and repetitively pulsed regimes with the electrooptical efficiency 20%. The sustaining of the COD plasma in argon and air is demonstrated at the atmospheric pressure. The emission properties of the COD plasma are studied and its possible applications are discussed. (lasers)

  11. Two-Dimensional Plasma Density Distributions in Low-Pressure Gas Discharges

    SciTech Connect

    Berlin, E.V.; Dvinin, S.A.; Mikheev, V.V.; Omarov, M.O.; Sviridkina, V. S.

    2004-12-15

    The plasma density distribution in a two-dimensional nonuniform positive column of a low-pressure gas discharge is studied in the hydrodynamic approximation with allowance for ion inertia. Exact solutions are derived for discharges in a rectangular and a cylindrical chamber. Asymptotic solutions near the coordinate origin and near the critical surface are considered. It is shown that, for potential plasma flows, the flow velocity component normal to the plasma boundary is equal to the ion acoustic velocity. The results obtained can be used to analyze the processes occurring in low-pressure plasmochemical reactors.

  12. Effect of the river discharge implementation in an operational model for the West Iberia coastal area.

    NASA Astrophysics Data System (ADS)

    Campuzano, Francisco; Brito, David; Juliano, Manuela; Fernandes, Rodrigo; Neves, Ramiro

    2015-04-01

    In the Iberian Peninsula, most of the largest rivers discharge on the Atlantic coast draining almost two thirds of the territory. It is an important source of nutrients and sediments to these coastal areas. Rivers discharges in the Atlantic area when compared with the ones in the Mediterranean side present the particularity that their water before is released into the ocean is previously mixed in their estuaries in a different ratio depending of the estuarine residence time and the discharged flow. In order to evaluate the relative importance of the inland waters in the circulation patterns of Western Iberia, the rivers discharges were implemented in the PCOMS model application (Portuguese Coast Operational Modelling System). To reproduce the water continuum including the different spatial and temporal scales, a methodology consisting in a system of integrated models using the Mohid model was designed. At the watershed level, the Mohid Land model calculated operationally water flow and properties, including nutrients, for the main river catchments of Western Iberian with a 2 km horizontal resolution. Downstream, several operational hydrodynamic and biological estuarine applications used those outcomes as model inputs, filling the gaps in the observation network. From the estuarine models, the tidally modulated water and properties fluxes to the coast were obtained. These fluxes were finally imposed in the Portuguese Coast Operational Modelling System (PCOMS), a fully 3D baroclinic hydrodynamic and ecological regional model that covers the Iberian Atlantic front. The fate of the rivers discharges were analysed by integrating model results in boxes, comparing the climatologies obtained with and without rivers and the rivers area of influence was obtained by lagrangian tracers simulations.

  13. Study of the switching rate of gas-discharge devices based on the open discharge with counter-propagating electron beams

    SciTech Connect

    Bokhan, P. A.; Gugin, P. P.; Lavrukhin, M. A.; Zakrevsky, Dm. E.

    2015-06-15

    The switching rate of gas-discharge devices “kivotrons” based on the open discharge with counter-propagating electron beams has been experimentally studied. Structures with 2-cm{sup 2} overall cathode area were examined. The switching time was found to show a monotonic decrease with increasing the working-gas helium pressure and with increasing the voltage across the discharge gap at breakdown. The minimum switching time was found to be ∼240 ps at 17 kV voltage, and the maximum rate of electric-current rise limited by the discharge-circuit inductance was 3 × 10{sup 12 }A/s.

  14. Modular Coating for Flexible Gas Turbine Operation

    NASA Astrophysics Data System (ADS)

    Zimmermann, J. R. A.; Schab, J. C.; Stankowski, A.; Grasso, P. D.; Olliges, S.; Leyens, C.

    2016-01-01

    In heavy duty gas turbines, the loading boundary conditions of MCrAlY systems are differently weighted for different operation regimes as well as for each turbine component or even in individual part locations. For an overall optimized component protection it is therefore of interest to produce coatings with flexible and individually tailored properties. In this context, ALSTOM developed an Advanced Modular Coating Technology (AMCOTEC™), which is based on several powder constituents, each providing specific properties to the final coating, in combination with a new application method, allowing in-situ compositional changes. With this approach, coating properties, such as oxidation, corrosion, and cyclic lifetime, etc., can be modularly adjusted for individual component types and areas. For demonstration purpose, a MCrAlY coating with modular ductility increase was produced using the AMCOTEC™ methodology. The method was proven to be cost effective and a highly flexible solution, enabling fast compositional screening. A calculation method for final coating composition was defined and validated. The modular addition of ductility agent enabled increasing the coating ductility with up to factor 3 with only slight decrease of oxidation resistance. An optimum composition with respect to ductility is reached with addition of 20 wt.% of ductility agent.

  15. Physical gas discharge procedure for adhesive surface pretreatment of polymer composite materials

    NASA Astrophysics Data System (ADS)

    Hahn, O.; Huesgen, B.

    The effects of corona discharge and low-pressure plasma treatments are examined with respect to the preparation of the adhesive surfaces of polymer composites. A glass-fiber-reinforced polyamide and an epoxy-based structural adhesive are employed and treated with the physical gas-discharge procedure. Attention is given to the wettability of the polymer surface and to the adhesive strengths of the joints for the two pretreatment procedures. Diagrams show the dependence of bonding strength and constant contact angle on the duration, performance, and storage times of the corona and plasma treatments. SEM is used to study the surface characteristics of the materials, and decomposition products are noted in the surfaces of the joints. Plasma treatments generally lead to more effective bonds in the polyamide specimens, and the corona-discharge treatment leads to good bonds with some surface modifications.

  16. Environmental policy constraints for acidic exhaust gas scrubber discharges from ships.

    PubMed

    Ülpre, H; Eames, I

    2014-11-15

    Increasingly stringent environmental legislation on sulphur oxide emissions from the combustion of fossil fuels onboard ships (International Maritime Organization (IMO) Regulation 14) can be met by either refining the fuel to reduce sulphur content or by scrubbing the exhaust gases. Commonly used open loop marine scrubbers discharge warm acidic exhaust gas wash water into the sea, depressing its pH. The focus on this paper is on the physics and chemistry behind the disposal of acidic discharges in seawater. The IMO Marine Environment Protection Committee (MEPC 59/24/Add.1 Annex 9) requires the wash water to reach a pH greater than 6.5 at a distance of 4m from the point of discharge. We examine the engineering constraints, specifically size and number of ports, to identify the challenges of meeting regulatory compliance. PMID:25284442

  17. Compressor discharge bleed air circuit in gas turbine plants and related method

    DOEpatents

    Anand, Ashok Kumar; Berrahou, Philip Fadhel; Jandrisevits, Michael

    2003-04-08

    A gas turbine system that includes a compressor, a turbine component and a load, wherein fuel and compressor discharge bleed air are supplied to a combustor and gaseous products of combustion are introduced into the turbine component and subsequently exhausted to atmosphere. A compressor discharge bleed air circuit removes bleed air from the compressor and supplies one portion of the bleed air to the combustor and another portion of the compressor discharge bleed air to an exhaust stack of the turbine component in a single cycle system, or to a heat recovery steam generator in a combined cycle system. In both systems, the bleed air diverted from the combustor may be expanded in an air expander to reduce pressure upstream of the exhaust stack or heat recovery steam generator.

  18. Compressor discharge bleed air circuit in gas turbine plants and related method

    DOEpatents

    Anand, Ashok Kumar; Berrahou, Philip Fadhel; Jandrisevits, Michael

    2002-01-01

    A gas turbine system that includes a compressor, a turbine component and a load, wherein fuel and compressor discharge bleed air are supplied to a combustor and gaseous products of combustion are introduced into the turbine component and subsequently exhausted to atmosphere. A compressor discharge bleed air circuit removes bleed air from the compressor and supplies one portion of the bleed air to the combustor and another portion of the compressor discharge bleed air to an exhaust stack of the turbine component in a single cycle system, or to a heat recovery steam generator in a combined cycle system. In both systems, the bleed air diverted from the combustor may be expanded in an air expander to reduce pressure upstream of the exhaust stack or heat recovery steam generator.

  19. 46 CFR 153.1130 - Failure of slops discharge recording equipment; operating with, reporting failures, and replacing...

    Code of Federal Regulations, 2013 CFR

    2013-10-01

    ... 46 Shipping 5 2013-10-01 2013-10-01 false Failure of slops discharge recording equipment; operating with, reporting failures, and replacing pollution equipment: Category A, B, C, D. 153.1130 Section... slops discharge recording equipment; operating with, reporting failures, and replacing...

  20. 46 CFR 153.1130 - Failure of slops discharge recording equipment; operating with, reporting failures, and replacing...

    Code of Federal Regulations, 2014 CFR

    2014-10-01

    ... 46 Shipping 5 2014-10-01 2014-10-01 false Failure of slops discharge recording equipment; operating with, reporting failures, and replacing pollution equipment: Category A, B, C, D. 153.1130 Section... slops discharge recording equipment; operating with, reporting failures, and replacing...

  1. 46 CFR 153.1130 - Failure of slops discharge recording equipment; operating with, reporting failures, and replacing...

    Code of Federal Regulations, 2012 CFR

    2012-10-01

    ... 46 Shipping 5 2012-10-01 2012-10-01 false Failure of slops discharge recording equipment; operating with, reporting failures, and replacing pollution equipment: Category A, B, C, D. 153.1130 Section... slops discharge recording equipment; operating with, reporting failures, and replacing...

  2. 46 CFR 153.1130 - Failure of slops discharge recording equipment; operating with, reporting failures, and replacing...

    Code of Federal Regulations, 2010 CFR

    2010-10-01

    ... 46 Shipping 5 2010-10-01 2010-10-01 false Failure of slops discharge recording equipment; operating with, reporting failures, and replacing pollution equipment: Category A, B, C, D. 153.1130 Section... slops discharge recording equipment; operating with, reporting failures, and replacing...

  3. 46 CFR 153.1130 - Failure of slops discharge recording equipment; operating with, reporting failures, and replacing...

    Code of Federal Regulations, 2011 CFR

    2011-10-01

    ... 46 Shipping 5 2011-10-01 2011-10-01 false Failure of slops discharge recording equipment; operating with, reporting failures, and replacing pollution equipment: Category A, B, C, D. 153.1130 Section... slops discharge recording equipment; operating with, reporting failures, and replacing...

  4. Plasma characteristics of argon glow discharge produced by AC power supply operating at low frequencies

    SciTech Connect

    Kongpiboolkid, Watcharapon; Mongkolnavin, Rattachat

    2015-04-24

    Non-thermal properties of Argon glow discharge operating with various operating pressures were measured and presented in this work. The Argon plasma is produced by a parallel conducting electrodes coupling with a high voltage AC power supply. The power supply can generate high AC voltage at various frequencies. The frequencies for the operation are in the range of a few kHz. The system is capable of generating electric field between the two metal electrodes discharge system. The characteristics of plasma produced were measured by optical emission spectroscopy (OES) technique where electron temperature (T{sub e}) and electron number density (n{sub e}) can be determined by line intensity ratio method. The value of electron number density was then determined from the Saha-Eggert equation. Our results show that the electron number density of the discharge obtained is of the order of 10{sup −17} − 10{sup −18} m{sup −3} where the electron temperature is between 1.00−2.00 eV for various operating frequencies used which are in good agreement with similar results published earlier.

  5. TOPICAL REVIEW: Numerical modelling of atmospheric pressure gas discharges leading to plasma production

    NASA Astrophysics Data System (ADS)

    Georghiou, G. E.; Papadakis, A. P.; Morrow, R.; Metaxas, A. C.

    2005-10-01

    In this paper, we give a detailed review of recent work carried out on the numerical characterization of non-thermal gas discharge plasmas in air at atmospheric pressure. First, we briefly describe the theory of discharge development for dielectric barrier discharges, which is central to the production of non-equilibrium plasma, and we present a hydrodynamic model to approximate the evolution of charge densities. The model consists of the continuity equations for electrons, positive and negative ions coupled to Poisson's equation for the electric field. We then describe features of the finite element flux corrected transport algorithm, which has been developed to specifically aim for accuracy (no spurious diffusion or oscillations), efficiency (through the use of unstructured grids) and ease of extension to complex 3D geometries in the framework of the hydrodynamic model in gas discharges. We summarize the numerical work done by other authors who have applied different methods to various models and then we present highlights of our own work, which includes code validation, comparisons with existing results and modelling of radio frequency systems, dc discharges, secondary effects such as photoionization and plasma production in the presence of dielectrics. The extension of the code to 3D for more realistic simulations is demonstrated together with the adaptive meshing technique, which serves to achieve higher efficiency. Finally, we illustrate the versatility of our scheme by using it to simulate the transition from non-thermal to thermal discharges. We conclude that numerical modelling and, in particular, the extension to 3D can be used to shed new light on the processes involved with the production and control of atmospheric plasma, which plays an important role in a host of emerging technologies.

  6. Is Submarine Groundwater Discharge a Gas Hydrate Formation Mechanism on the Circum-Arctic Shelf?

    NASA Astrophysics Data System (ADS)

    Frederick, J. M.; Buffett, B. A.

    2015-12-01

    Methane hydrate is an ice-like solid that can sequester large quantities of methane gas in marine sediments along most continental margins where thermodynamic conditions permit its formation. Along the circum-Arctic shelf, relict permafrost-associated methane hydrate deposits formed when non-glaciated portions of the shelf experienced subaerial exposure during ocean transgressions. Gas hydrate stability and the permeability of circum-Arctic shelf sediments to gas migration is closely linked with relict submarine permafrost. Heat flow observations on the Alaskan North Slope and Canadian Beaufort Shelf suggest the movement of groundwater offshore, but direct observations of groundwater flow do not exist. Submarine discharge, an offshore flow of fresh, terrestrial groundwater, can affect the temperature and salinity field in shelf sediments, and may be an important factor in submarine permafrost and gas hydrate evolution on the Arctic continental shelf. Submarine groundwater discharge may also enhance the transport of organic matter for methanogenesis within marine sediments. Because it is buoyancy-driven, the velocity field contains regions with a vertical (upward) component as groundwater flows offshore. This combination of factors makes submarine groundwater discharge a potential mechanism controlling permafrost-associated gas hydrate evolution on the Arctic continental shelf. In this study, we quantitatively investigate the feasibility of submarine groundwater discharge as a control on permafrost-associated gas hydrate formation on the Arctic continental shelf, using the Canadian Beaufort Shelf as an example. We have developed a shelf-scale, two-dimensional numerical model based on the finite volume method for two-phase flow of pore fluid and methane gas within Arctic shelf sediments. The model tracks the evolution of the pressure, temperature, salinity, methane gas, methane hydrate, and permafrost fields given imposed boundary conditions, with latent heat of

  7. [Study on vibrational temperature and gas temperature in a hollowneedle-plate discharge plasma].

    PubMed

    Dong, Li-fang; Liu, Wei-yuan; Yang, Yu-jie; Wang, Shuai

    2010-09-01

    A 1.6-3 cm long plasma torch was generated when argon gas was introduced by using a hollowneedle-plate discharge device working in atmosphere. The vibrational temperature and the gas temperature at plasma root and tip were studied by using optical emission spectrum at different argon gas flow. The gas temperature was obtained by comparing experimental line shape of OH radicals band around 309 nm with its simulated line shape. The vibrational temperature was calculated using N2 second posi tive band system C3:pi u-B3 pi g. It was found that the gas temperatures at arc root and arc tip are equal and they decrease with the argon flow rate increasing. The gas temperature decreases from 350 to 300 K when argon flow rate increases from 3.0 to 6.5 mL x min(-1). The vibrational temperature at are tip (1950 K) is higher than that at arc root (1755 K) under a low gas flow rate (e.g., 3.0 mL x min(-1)). With gas flow rate increasing, the vibrational temperature at both tip and root decreases, but the decreasing rate at are tip is faster than that at arc root. When gas flow is larger, the vibrational temperatures at tip and root tend to be equal. PMID:21105384

  8. Electron density measurement in gas discharge plasmas by optical and acoustic methods

    NASA Astrophysics Data System (ADS)

    Biagioni, A.; Anania, M. P.; Bellaveglia, M.; Chiadroni, E.; Cianchi, A.; Di Giovenale, D.; Di Pirro, G.; Ferrario, M.; Filippi, F.; Mostacci, A.; Pompili, R.; Shpakov, V.; Vaccarezza, C.; Villa, F.; Zigler, A.

    2016-08-01

    Plasma density represents a very important parameter for both laser wakefield and plasma wakefield acceleration, which use a gas-filled capillary plasma source. Several techniques can be used to measure the plasma density within a capillary discharge, which are mainly based on optical diagnostic methods, as for example the well-known spectroscopic method using the Stark broadening effect. In this work, we introduce a preliminary study on an alternative way to detect the plasma density, based on the shock waves produced by gas discharge in a capillary. Firstly, the measurements of the acoustic spectral content relative to the laser-induced plasmas by a solid target allowed us to understand the main properties of the acoustic waves produced during this kind of plasma generation; afterwards, we have extended such acoustic technique to the capillary plasma source in order to calibrate it by comparison with the stark broadening method.

  9. Coulomb collisions in the Boltzmann equation for electrons in low-temperature gas discharge plasmas

    NASA Astrophysics Data System (ADS)

    Hagelaar, G. J. M.

    2016-02-01

    This paper investigates the effects of electron-electron and electron-ion Coulomb collisions on the electron distribution function and transport coefficients obtained from the Boltzmann equation for simple dc gas discharge conditions. Expressions are provided for the full Coulomb collision terms acting on both the isotropic and anisotropic parts of the electron distribution function, which are then incorporated in the freeware Boltzmann equation solver BOLSIG+. Different Coulomb collision effects are demonstrated and discussed on the basis of BOLSIG+  results for argon gas. It is shown that the anisotropic part of the electron-electron collision term, neglected in previous work, can in certain cases have a large effect on the electron mobility and is essential when describing the transition towards the Coulomb-collision dominated regime characterized by Spitzer transport coefficients. Finally, a brief overview is presented of the discharge conditions for which different Coulomb collision effects occur in different gases.

  10. Thermal poling of ferroelectrets: How does the gas temperature influence dielectric barrier discharges in cavities?

    NASA Astrophysics Data System (ADS)

    Qiu, Xunlin; Wirges, Werner; Gerhard, Reimund

    2016-06-01

    The influence of the temperature in the gas-filled cavities on the charging process of ferroelectret film systems has been studied in hysteresis measurements. The threshold voltage and the effective polarization of the ferroelectrets were determined as functions of the charging temperature TP. With increasing TP, the threshold voltage for triggering dielectric barrier discharges in ferroelectrets decreases. Thus, increasing the temperature facilitates the charging of ferroelectrets. However, a lower threshold voltage reduces the attainable remanent polarization because back discharges occur at lower charge levels, as soon as the charging voltage is turned off. The results are discussed in view of Paschen's law for electrical breakdown, taking into account the respective gas temperature and a simplified model for ferroelectrets. Our results indicate that the thermal poling scheme widely used for conventional ferroelectrics is also useful for electrically charging ferroelectrets.

  11. Behaviour Of Gas Conditions During Vacuum Arc Discharges Used For Deposition Of Thin Films

    NASA Astrophysics Data System (ADS)

    Strzyzewski, P.; Catani, L.; Cianchi, A.; Langner, J.; Lorkiewicz, J.; Mirowski, R.; Russo, R.; Sadowski, M.; Tazzari, S.; Witkowski, J.

    2006-01-01

    The paper concerns an important problem which is connected with the inclusion of some impurities in the deposited metal film. It was found that appearance of contaminants in the film is induced mainly by water vapor remnants inside the vacuum chamber. The paper presents information on changes in the gas composition during and between arc-discharges, which is of primary importance for the selection of appropriate experimental conditions.

  12. Visible and near-ultraviolet spectra of low-pressure rare-gas microwave discharges

    NASA Technical Reports Server (NTRS)

    Campbell, J. P.; Spisz, E. W.; Bowman, R. L.

    1971-01-01

    The spectral emission characteristics of three commercial low pressure rare gas discharge lamps wire obtained in the near ultraviolet and visible wavelength range. All three lamps show a definite continuum over the entire wavelength range from 0.185 to 0.6 micrometers. Considerable line emission is superimposed on much of the continuum for wavelengths greater than 0.35 micrometers. These sources were used to make transmittance measurements on quartz samples in the near ultraviolet wavelength range.

  13. Electron beam method and apparatus for obtaining uniform discharges in electrically pumped gas lasers

    DOEpatents

    Fenstermacher, Charles A.; Boyer, Keith

    1986-01-01

    A method and apparatus for obtaining uniform, high-energy, large-volume electrical discharges in the lasing medium of a gas laser whereby a high-energy electron beam is used as an external ionization source to ionize substantially the entire volume of the lasing medium which is then readily pumped by means of an applied potential less than the breakdown voltage of the medium. The method and apparatus are particularly useful in CO.sub.2 laser systems.

  14. VUV generation by adiabatically expanded and excited by a DC electrical discharge Argon gas

    SciTech Connect

    Pipergias, K.; Yasemidis, D.; Reppa, E.; Pentaris, D.; Efthimiopoulos, T.; Merlemis, N.; Giannetas, V.

    2010-11-10

    We investigate the emission of Argon (Ar) gas which is adiabatically expanded through a nozzle and excited using a DC electrical discharge. Because of the expansion and the electronic excitation, Ar dimers and clusters are formed, which give radiation in the second (2nd) and in the third (3rd) continua of Ar, centered at about 126 and 254 nm respectively. We particularly focus our study on the 2nd continuum, in order to develop a laser at this wavelength.

  15. A method for removal of CO from exhaust gas using pulsed corona discharge.

    PubMed

    Li, X; Yang, L; Lei, Y; Wang, J; Lu, Y

    2000-10-01

    An experimental study of the oxidation of CO in exhaust gas from a motorcycle has been carried out using plasma chemical reactions in a pulsed corona discharge. In the process, some main parameters, such as the initial CO concentration, amplitude and frequency of pulses, residence time, reactor volume, and relative humidity (RH), as well as their effects on CO removal characteristics, were investigated. O3, which is beneficial to reducing CO, was produced during CO removal. When the exhaust gas was at ambient temperature, more than 80% CO removal efficiency was realized at an initial concentration of 288 ppm in a suitable range of the parameters. PMID:11288300

  16. Multifrequency laser probing of CO-containing gas mixtures excited in a pulsed discharge

    SciTech Connect

    Ionin, Andrei A; Klimachev, Yu M; Kozlov, A Yu; Kotkov, A A; Rulev, O A; Seleznev, L V; Sinitsyn, D V

    2007-03-31

    The method of multifrequency laser probing is developed which can be used for diagnostics of the temperature and population of vibrational levels in gas mixtures containing CO molecules in excited vibrational states. The method is tested by studying the dynamics of the gas temperature and population of vibrational levels of the CO molecule in gas mixtures excited by a pulsed discharge. It is shown that the method provides the reduction of the gas temperature measurement error down to 3%. It is found that the population of lower vibrational levels in the CO-O{sub 2} mixture can exceed the population of levels in CO-He and CO-N{sub 2} laser mixtures by several times. (active media)

  17. Design for gas chromatography-corona discharge-ion mobility spectrometry.

    PubMed

    Jafari, Mohammad T; Saraji, Mohammad; Sherafatmand, Hossein

    2012-11-20

    A corona discharge ionization-ion mobility spectrometry (CD-IMS) with a novel sample inlet system was designed and constructed as a detector for capillary gas chromatography. In this design, a hollow needle was used instead of a solid needle which is commonly used for corona discharge creation, helping us to have direct axial interfacing for GC-IMS. The capillary column was passed through the needle, resulting in a reaction of effluents with reactant ions on the upstream side of the corona discharge ionization source. Using this sample introduction design, higher ionization efficiency was achieved relative to the entrance direction through the side of the drift tube. In addition, the volume of the ionization region was reduced to minimize the resistance time of compounds in the ionization source, increasing chromatographic resolution of the instrument. The effects of various parameters such as drift gas flow, makeup gas flow, and column tip position inside the needle were investigated. The designed instrument was exhaustively validated in terms of sensitivity, resolution, and reproducibility by analyzing the standard solutions of methyl isobutyl ketone, heptanone, nonanone, and acetophenone as the test compounds. The results obtained by CD-IMS detector were compared with those of the flame ionization detector, which revealed the capability of the proposed GC-IMS for two-dimensional separation (based on the retention time and drift time information) and identification of an analyte in complex matrixes. PMID:23083064

  18. Theoretical Study of Plasma Parameters Dependence on Gas Temperature in an Atmospheric Pressure Argon Microwave Discharge

    SciTech Connect

    Pencheva, M.; Benova, E.; Zhelyazkov, I.

    2008-03-19

    The gas temperature is an important parameter in many applications of atmospheric pressure microwave discharges (MW). That is why it is necessary to study the influence of that temperature on the plasma characteristics. Our investigation is based on a self-consistent model including the wave electrodynamics and gas-discharge kinetics. We adopt a blocks' energy structure of the argon excited atom. More specifically, we consider 7 different blocks of states, namely 4s, 4p, 3d, 5s, 5p, 4d, and 6s. Each block k is characterized by its effective energy uk (derived as an average energy of all levels in the block), as well as its effective g-factor and population. The argon dimmer, atomic and molecular ions are also taken into account in the model. We solve the Boltzmann equation in order to get the electron energy distribution function and the necessary rate constants of the elementary processes. The collisional-radiative part of the model is based on 87 processes. As a result we obtain the electron and ions' number densities, mean electron energy, mean power for sustaining an electron--ion pair in the discharge bulk, as well as the population of the excited blocks of states of the argon atom as functions of the gas temperature.

  19. Theoretical Study of Plasma Parameters Dependence on Gas Temperature in an Atmospheric Pressure Argon Microwave Discharge

    NASA Astrophysics Data System (ADS)

    Pencheva, M.; Benova, E.; Zhelyazkov, I.

    2008-03-01

    The gas temperature is an important parameter in many applications of atmospheric pressure microwave discharges (MW). That is why it is necessary to study the influence of that temperature on the plasma characteristics. Our investigation is based on a self-consistent model including the wave electrodynamics and gas-discharge kinetics. We adopt a blocks' energy structure of the argon excited atom. More specifically, we consider 7 different blocks of states, namely 4s, 4p, 3d, 5s, 5p, 4d, and 6s. Each block k is characterized by its effective energy uk (derived as an average energy of all levels in the block), as well as its effective g-factor and population. The argon dimmer, atomic and molecular ions are also taken into account in the model. We solve the Boltzmann equation in order to get the electron energy distribution function and the necessary rate constants of the elementary processes. The collisional-radiative part of the model is based on 87 processes. As a result we obtain the electron and ions' number densities, mean electron energy, mean power for sustaining an electron—ion pair in the discharge bulk, as well as the population of the excited blocks of states of the argon atom as functions of the gas temperature.

  20. HOLLOW CARBON ARC DISCHARGE

    DOEpatents

    Luce, J.S.

    1960-10-11

    A device is described for producing an energetic, direct current, hollow, carbon-arc discharge in an evacuated container and within a strong magnetic field. Such discharges are particularly useful not only in dissociation and ionization of high energy molecular ion beams, but also in acting as a shield or barrier against the instreaming of lowenergy neutral particles into a plasma formed within the hollow discharge when it is used as a dissociating mechanism for forming the plasma. There is maintained a predetermined ratio of gas particles to carbon particles released from the arc electrodes during operation of the discharge. The carbon particles absorb some of the gas particles and are pumped along and by the discharge out of the device, with the result that smaller diffusion pumps are required than would otherwise be necessary to dispose of the excess gas.

  1. Towards sustainability in offshore oil and gas operations

    NASA Astrophysics Data System (ADS)

    Khan, M. Ibrahim

    Human activities are causing irreversible damage to the natural world and threaten our ability to sustain future generations. According to Millennium Ecosystem Assessment of 2005, sixty percent of world pristine habitats are destroyed or disturbed and species extinction rate is 100-1000 times higher than the normal background rate. One of the main reasons of these problems is the use of unsustainable technology. In this dissertation, the essential features of the modern technology development are discussed and a new single-parameter screening criterion is proposed. This criterion will allow the development of truly sustainable technologies. Previously developed technologies, particularly the ones developed after the industrial revolution, are evaluated based on the new criterion. The root cause for unsustainability of these technologies especially in the energy sector is discussed. The proposed criterion is applied to the petroleum sector. Petroleum hydrocarbons are considered to be the lifeblood of the modern society. Petroleum industry that took off from the golden era of 1930's never ceased to dominate all aspects of our society. Until now, there is no suitable alternative to fossil fuel and all trends indicate continued dominance of the petroleum industry in the foreseeable future. Even though petroleum operations have been based on solid scientific excellence and engineering marvels; only recently it has been discovered that many of the practices are not environmentally sustainable. Practically all activities of hydrocarbon operations are accompanied by undesirable discharges of liquid, solid, and gaseous wastes, which have enormous impacts on the environment. Consequently, reducing environmental impact is the most pressing issue today and many environmentalist groups are calling for curtailing petroleum operations altogether. There is clearly a need to develop a new management approach in hydrocarbon operations. This approach will have to be environmentally

  2. Arterial gas occlusions in operating heat pipes

    NASA Technical Reports Server (NTRS)

    Saaski, E. W.

    1975-01-01

    The effect of noncondensable gases on high performance arterial heat pipes has been investigated both analytically and experimentally. Models have been generated which characterize the dissolution of gases in condensate and the diffusional loss of dissolved gases from condensate in arterial flow. These processes, and others, have been used to postulate stability criteria for arterial heat pipes. Experimental observations of gas occlusions were made using a stainless steel heat pipe equipped with viewing ports, and the working fluids methanol and ammonia with the gas additives helium, argon, and xenon. Observations were related to gas transport models.

  3. Analytical model of atmospheric pressure, helium/trace gas radio-frequency capacitive Penning discharges

    NASA Astrophysics Data System (ADS)

    Lieberman, M. A.

    2015-04-01

    Atmospheric and near-atmospheric pressure, helium/trace gas radio-frequency capacitive discharges have wide applications. An analytic equilibrium solution is developed based on a homogeneous, current-driven discharge model that includes sheath and electron multiplication effects and contains two electron populations. A simplified chemistry is used with four unknown densities: hot electrons, warm electrons, positive ions and metastables. The dominant electron-ion pair production is Penning ionization, and the dominant ion losses are to the walls. The equilibrium particle balances are used to determine a single ionization balance equation for the warm electron temperature, which is solved, both approximately within the α- and γ-modes, and exactly by conventional root-finding techniques. All other discharge parameters are found, the extinction and α-γ transitions are determined, and a similarity law is given, in which the equilibrium for a short gap at high pressure can be rescaled to a longer gap at lower pressure. Within the α-mode, we find the scaling of the discharge parameters with current density, frequency, gas density and gap width. The analytic results are compared to hybrid and particle-in-cell (PIC) results for He/0.1%N2, and to hybrid results for He/0.1%H2O. For nitrogen, a full reaction set is used for the hybrid calculations and a simplified reaction set for the PIC simulations. For the chemically complex water trace gas, a set of 209 reactions among 43 species is used. The analytic results are found to be in reasonably good agreement with the more elaborate hybrid and PIC calculations.

  4. Effect of hydrogen ratio on plasma parameters of N{sub 2}-H{sub 2} gas mixture glow discharge

    SciTech Connect

    El-Brulsy, R. A.; Abd Al-Halim, M. A.; Abu-Hashem, A.; Rashed, U. M.; Hassouba, M. A.

    2012-05-15

    A dc plane glow discharge in a nitrogen-hydrogen (N{sub 2}-H{sub 2}) gas mixture has been operated at discharge currents of 10 and 20 mA. The electron energy distribution function (EEDF) at different hydrogen concentrations is measured. A Maxwellian EEDF is found in the positive column region, while in both cathode fall and negative glow regions, a non-Maxwellian one is observed. Langmuir electric probes are used at different axial positions, gas pressures, and hydrogen concentrations to measure the electron temperature and plasma density. The electron temperature is found to increase with increasing H{sub 2} concentration and decrease with increasing both the axial distance from the cathode and the mixture pressure. At first, with increasing distance from the cathode, the ion density decreases, while the electron density increases; then, as the anode is further approached, they remain nearly constant. At different H{sub 2} concentrations, the electron and ion densities decrease with increasing the mixture pressure. Both the electron and ion densities slightly decrease with increasing H{sub 2} concentration.

  5. Effect of Submarine Groundwater Discharge on Relict Arctic Submarine Permafrost and Gas Hydrate

    NASA Astrophysics Data System (ADS)

    Frederick, J. M.; Buffett, B. A.

    2014-12-01

    Permafrost-associated gas hydrate deposits exist at shallow depths within the sediments of the circum-Arctic continental shelves. Degradation of this shallow water reservoir has the potential to release large quantities of methane gas directly to the atmosphere. Gas hydrate stability and the permeability of the shelf sediments to gas migration is closely linked with submarine permafrost. Submarine permafrost extent depends on several factors, such as the lithology, sea level variations, mean annual air temperature, ocean bottom water temperature, geothermal heat flux, and the salinity of the pore water. The salinity of the pore water is especially relevant because it partially controls the freezing point for both ice and gas hydrate. Measurements of deep pore water salinity are few and far between, but show that deep off-shore sediments are fresh. Deep freshening has been attributed to large-scale topographically-driven submarine groundwater discharge, which introduces fresh terrestrial groundwater into deep marine sediments. We investigate the role of submarine ground water discharge on the salinity field and its effects on the seaward extent of relict submarine permafrost and gas hydrate stability on the Arctic shelf with a 2D shelf-scale model based on the finite volume method. The model tracks the evolution of the temperature, salinity, and pressure fields given imposed boundary conditions, with latent heat of water ice and hydrate formation included. The permeability structure of the sediments is coupled to changes in permafrost. Results show that pore fluid is strongly influenced by the permeability variations imposed by the overlying permafrost layer. Groundwater discharge tends to travel horizontally off-shore beneath the permafrost layer and the freshwater-saltwater interface location displays long timescale transient behavior that is dependent on the groundwater discharge strength. The seaward permafrost extent is in turn strongly influenced by the

  6. Analysis of double-probe characteristics in low-frequency gas discharges and its improvement

    SciTech Connect

    Liu, DongLin Li, XiaoPing; Xie, Kai; Liu, ZhiWei; Shao, MingXu

    2015-01-15

    The double-probe has been used successfully in radio-frequency discharges. However, in low-frequency discharges, the double-probe I-V curve is so much seriously distorted by the strong plasma potential fluctuations that the I-V curve may lead to a large estimate error of plasma parameters. To suppress the distortion, we investigate the double-probe characteristics in low-frequency gas discharge based on an equivalent circuit model, taking both the plasma sheath and probe circuit into account. We discovered that there are two primary interferences to the I-V curve distortion: the voltage fluctuation between two probe tips caused by the filter difference voltage and the current peak at the negative edge of the plasma potential. Consequently, we propose a modified passive filter to reduce the two types of interference simultaneously. Experiments are conducted in a glow-discharge plasma (f = 30 kHz) to test the performance of the improved double probe. The results show that the electron density error is reduced from more than 100% to less than 10%. The proposed improved method is also suitable in cases where intensive potential fluctuations exist.

  7. Organic acids enhanced decoloration of azo dye in gas phase surface discharge plasma system.

    PubMed

    Wang, Tiecheng; Qu, Guangzhou; Ren, Jingyu; Sun, Qiuhong; Liang, Dongli; Hu, Shibin

    2016-01-25

    A gas phase surface discharge plasma combined with organic acids system was developed to enhance active species mass transfer and dye-containing wastewater treatment efficacy, with Acid Orange II (AO7) as the model pollutant. The effects of discharge voltage and various organic acid additives (acetic acid, lactic acid and nonoic acid) on AO7 decoloration efficiency were evaluated. The experimental results showed that an AO7 decoloration efficiency of approximately 69.0% was obtained within 4 min of discharge plasma treatment without organic acid addition, which was improved to 82.8%, 83.5% and 88.6% within the same treatment time with the addition of acetic acid, lactic acid and nonoic acid, respectively. The enhancement effects on AO7 decoloration efficiency could be attributed to the decrease in aqueous surface tension, improvement in bubble distribution and shape, and increase in ozone equivalent concentration. The AO7 wastewater was biodegradable after discharge plasma treatment with the addition of organic acid. AO7 decomposition intermediates were analyzed by UV-vis spectrometry and GC-MS; 2-naphthol, 1,4-benzoquinone, phthalic anhydride, coumarin, 1,2-naphthoquinone, and 2-formyl-benzoic acid were detected. A possible pathway for AO7 decomposition in this system was proposed. PMID:26444488

  8. Specific features of an electric discharge operating between an electrolytic anode and a metal cathode

    NASA Astrophysics Data System (ADS)

    Gaisin, A. F.; Sarimov, L. R.

    2011-06-01

    Results are presented from experimental studies of a high-current electric discharge operating between an St45 steel cathode and a service water anode in a wide range of air pressures. Peculiarities of discharge ignition and specific features of cathode and anode spots were revealed. The behavior of the current density on a service water anode was investigated for the first time. Comparison of the current densities j on the steel cathode and service water anode shows that, in the parameter range under study, Hehl's law is not satisfied on the water anode. The two-dimensional distribution of the potential inside and on the surface of the service water anode was measured.

  9. Plasma Discharges in Gas Bubbles in Liquid Water: Breakdown Mechanisms and Resultant Chemistry

    NASA Astrophysics Data System (ADS)

    Gucker, Sarah M. N.

    The use of atmospheric pressure plasmas in gases and liquids for purification of liquids has been investigated by numerous researchers, and is highly attractive due to their strong potential as a disinfectant and sterilizer. However, the fundamental understanding of plasma production in liquid water is still limited. Despite the decades of study dedicated to electrical discharges in liquids, many physical aspects of liquids, such as the high inhomogeneity of liquids, complicate analyses. For example, the complex nonlinearities of the fluid have intricate effects on the electric field of the propagating streamer. Additionally, the liquid material itself can vaporize, leading to discontinuous liquid-vapor boundaries. Both can and do often lead to notable hydrodynamic effects. The chemistry of these high voltage discharges on liquid media can have circular effects, with the produced species having influence on future discharges. Two notable examples include an increase in liquid conductivity via charged species production, which affects the discharge. A second, more complicated scenario seen in some liquids (such as water) is the doubling or tripling of molecular density for a few molecule layers around a high voltage electrode. These complexities require technological advancements in optical diagnostics that have only recently come into being. This dissertation investigates several aspects of electrical discharges in gas bubbles in liquids. Two primary experimental configurations are investigated: the first allows for single bubble analysis through the use of an acoustic trap. Electrodes may be brought in around the bubble to allow for plasma formation without physically touching the bubble. The second experiment investigates the resulting liquid phase chemistry that is driven by the discharge. This is done through a dielectric barrier discharge with a central high voltage surrounded by a quartz discharge tube with a coil ground electrode on the outside. The plasma

  10. A compact repetitive high-voltage nanosecond pulse generator for the application of gas discharge.

    PubMed

    Pang, Lei; Zhang, Qiaogen; Ren, Baozhong; He, Kun

    2011-04-01

    Uniform and stable discharge plasma requires very short duration pulses with fast rise times. A repetitive high-voltage nanosecond pulse generator for the application of gas discharge is presented in this paper. It is constructed with all solid-state components. Two-stage magnetic compression is used to generate a short duration pulse. Unlike in some reported studies, common commercial fast recovery diodes instead of a semiconductor opening switch (SOS) are used in our experiment that plays the role of SOS. The SOS-like effects of four different kinds of diodes are studied experimentally to optimize the output performance. It is found that the output pulse voltage is higher with a shorter reverse recovery time, and the rise time of pulse becomes faster when the falling time of reverse recovery current is shorter. The SOS-like effect of the diodes can be adjusted by changing the external circuit parameters. Through optimization the pulse generator can provide a pulsed voltage of 40 kV with a 40 ns duration, 10 ns rise time, and pulse repetition frequency of up to 5 kHz. Diffuse plasma can be formed in air at standard atmospheric pressure using the developed pulse generator. With a light weight and small packaging the pulse generator is suitable for gas discharge application. PMID:21529005