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Sample records for oxygen plasma processing

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

    SciTech Connect

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

    2015-11-15

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

  2. Poly (ethylene terephthalate) decomposition process in oxygen plasma; emission spectroscopic and surface analysis for oxygen-plasma reaction

    NASA Astrophysics Data System (ADS)

    Kumagai, Hidetoshi; Hiroki, Denbo; Fujii, Nobuyuki; Kobayashi, Takaomi

    2004-01-01

    Emission spectroscopy was applied to observe the reaction process of poly (ethylene terephthalate) (PET) in an oxygen (O2) plasma generated by a microwave discharge. As the PET was exposed in the O2 plasma flow, light emitted from the PET surface was monitored. In the diagnosis measurement, several emission peaks assigned to the Hα atomic line at 652 nm, Hβ at 486 nm, OH (2Σ-->2Π) transition near 244-343 nm and CO (b3 Σ-->a3 Σ) near 283-370 nm were observed and measured at various discharge times. These results indicated that after the plasma etching, the PET sample was decomposed by the oxygen plasma reaction, and then, hydrogen abstraction and carbon oxidation processes. We also observed the time profile of oxygen atom, as the atom-emission intensity at 777 nm was monitored. As Hβ atomic and OH molecule lines appeared in the presence of PET, the O atom intensity was significantly reduced. In the surface analysis on Fourier transform infrared and x-ray photoelectron spectroscopy measurements, it was found that for the PET surface treated by O2 plasma containing excited atomic oxygen species, ester bands were broken and carbonization formed on the PET surface. .

  3. The reaction pathways of the oxygen plasma pulse in the hafnium oxide atomic layer deposition process

    SciTech Connect

    Jeon, Hyeongtag; Won, Youngdo

    2008-09-22

    The plasma enhanced atomic layer deposition process for the HfO{sub 2} thin film is modeled as simple reactions between Hf(OH){sub 3}NH{sub 2} and reactive oxygen species. The density functional theory calculation was performed for plausible reaction pathways to construct the reaction profile. While the triplet molecular oxygen is unlikely to form a reactive complex, the singlet molecular oxygen forms the stable adduct that goes through the transition state and completes the reaction pathway to the products. Either two singlet or two triplet oxygen atoms make the singlet adduct complex, which follows the same pathway to the product as the singlet molecular oxygen reacts.

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

    SciTech Connect

    Adams, B.E.

    1996-11-01

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

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

    NASA Technical Reports Server (NTRS)

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

    1990-01-01

    The utilization of a cold plasma in chlorination processing is described. Essential equipment and instruments were received, the experimental apparatus assembled and tested, and preliminary experiments conducted. The results of the latter lend support to the original hypothesis: a cold plasma can both significantly enhance and bias chemical reactions. In two separate experiments, a cold plasma was used to reduce TiCl4 vapor and chlorinate ilmenite. The latter, reacted in an argon-chlorine plasma, yielded oxygen. The former experiment reveals that chlorine can be recovered as HCl vapor from metal chlorides in a hydrogen plasma. Furthermore, the success of the hydrogen experiments has lead to an analysis of the feasibility of direct hydrogen reduction of metal oxides in a cold plasma. That process would produce water vapor and numerous metal by-products.

  6. Sterilization by oxygen plasma

    NASA Astrophysics Data System (ADS)

    Moreira, Adir José; Mansano, Ronaldo Domingues; Andreoli Pinto, Terezinha de Jesus; Ruas, Ronaldo; Zambon, Luis da Silva; da Silva, Mônica Valero; Verdonck, Patrick Bernard

    2004-07-01

    The use of polymeric medical devices has stimulated the development of new sterilization methods. The traditional techniques rely on ethylene oxide, but there are many questions concerning the carcinogenic properties of the ethylene oxide residues adsorbed on the materials after processing. Another common technique is the gamma irradiation process, but it is costly, its safe operation requires an isolated site and it also affects the bulk properties of the polymers. The use of a gas plasma is an elegant alternative sterilization technique. The plasma promotes an efficient inactivation of the micro-organisms, minimises the damage to the materials and presents very little danger for personnel and the environment. Pure oxygen reactive ion etching type of plasmas were applied to inactivate a biologic indicator, the Bacillus stearothermophilus, to confirm the efficiency of this process. The sterilization processes took a short time, in a few minutes the mortality was complete. In situ analysis of the micro-organisms' inactivating time was possible using emission spectrophotometry. The increase in the intensity of the 777.5 nm oxygen line shows the end of the oxidation of the biologic materials. The results were also observed and corroborated by scanning electron microscopy.

  7. Nanopore formation process in artificial cell membrane induced by plasma-generated reactive oxygen species.

    PubMed

    Tero, Ryugo; Yamashita, Ryuma; Hashizume, Hiroshi; Suda, Yoshiyuki; Takikawa, Hirofumi; Hori, Masaru; Ito, Masafumi

    2016-09-01

    We investigated morphological change of an artificial lipid bilayer membrane induced by oxygen radicals which were generated by non-equilibrium atmospheric pressure plasma. Neutral oxygen species, O((3)Pj) and O2((1)Δg), were irradiated of a supported lipid bilayer existing under a buffer solution at various conditions of dose time and distances, at which the dose amounts of the oxygen species were calculated quantitatively. Observation using an atomic force microscope and a fluorescence microscope revealed that dose of the neutral oxygen species generated nanopores with the diameter of 10-50 nm in a phospholipid bilayer, and finally destructed the bilayer structure. We found that protrusions appeared on the lipid bilayer surface prior to the formation of nanopores, and we attributed the protrusions to the precursor of the nanopores. We propose a mechanism of the pore formation induced by lipid oxidation on the basis of previous experimental and theoretical studies. PMID:27216034

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

    NASA Technical Reports Server (NTRS)

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

    1991-01-01

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

  9. Effects of halogen doping on nanocarbon catalysts synthesized by a solution plasma process for the oxygen reduction reaction.

    PubMed

    Ishizaki, Takahiro; Wada, Yuta; Chiba, Satoshi; Kumagai, Sou; Lee, Hoonseung; Serizawa, Ai; Li, Oi Lun; Panomsuwan, Gasidit

    2016-08-01

    Halogen-doped carbon nanoparticles (CNPs) were synthesized by a simple one-step solution plasma process at room temperature using a mixture of benzene (C6H6) and organics containing halogen atoms as the precursors (i.e., hexafluorobenzene (C6F6), hexachlorobenzene (C6Cl6), and hexabromobenzene (C6Br6)). The experimental results demonstrated that halogen doping, especially F and Cl, could lead to more efficient removal of residual hydrogen compared to carbon synthesized with pure benzene. This phenomenon was related to the different binding energies between hydrogen and halogens to form hydrogen halides. Their crystallinity and morphology did not change and remained the same as non-doped carbon. The electrochemical evaluation of oxygen reduction reaction (ORR) activity in an alkaline solution revealed that halogen doping did not play a significant role in shifting the onset potential for the ORR, while a slight enhancement in diffusion limited current density was observed at high overpotentials. Moreover, the electron transfer number involved in the ORR process determined from the Koutecky-Levich plot at -0.6 V was found to increase for halogen-doped carbons in the following order: F-CNPs > Br-CNPs > Cl-CNPs > CNPs. The improved ORR performance of F-CNPs could reasonably be attributed to the synergistic effects of specific bonding states between the halogen and carbon, structural defects and surface functional groups. Our results confirmed the validity of using halogen doping to improve the ORR catalytic activity of CNPs. PMID:27435811

  10. Replacement of hydrogen peroxide cleaning with oxygen plasma

    NASA Astrophysics Data System (ADS)

    Adams, B. E.

    1992-03-01

    Comparison between the standard peroxide cleaning method and an oxygen plasma modified version was run on thin film bond monitors. The plasma modified version substituted oxygen plasma for the peroxide cleaning step in the process and reduced the DI rinse water temperature from 75 C to 25 C. A direct surface cleanliness comparison was made between the two cleaning methods using Auger spectroscopy. A beam lead and ribbon bonding experiment was also run on plasma-cleaned networks. Results of both experiments indicate that plasma cleaning is superior to peroxide cleaning and that reliable bonding can be done on plasma-cleaned thin film networks.

  11. Biochar activated by oxygen plasma for supercapacitors

    NASA Astrophysics Data System (ADS)

    Gupta, Rakesh Kumar; Dubey, Mukul; Kharel, Parashu; Gu, Zhengrong; Fan, Qi Hua

    2015-01-01

    Biochar, also known as black carbon, is a byproduct of biomass pyrolysis. As a low-cost, environmental-friendly material, biochar has the potential to replace more expensive synthesized carbon nanomaterials (e.g. carbon nanotubes) for use in future supercapacitors. To achieve high capacitance, biochar requires proper activation. A conventional approach involves mixing biochar with a strong base and baking at a high temperature. However, this process is time consuming and energy inefficient (requiring temperatures >900 °C). This work demonstrates a low-temperature (<150 °C) plasma treatment that efficiently activates a yellow pine biochar. Particularly, the effects of oxygen plasma on the biochar microstructure and supercapacitor characteristics are studied. Significant enhancement of the capacitance is achieved: 171.4 F g-1 for a 5-min oxygen plasma activation, in comparison to 99.5 F g-1 for a conventional chemical activation and 60.4 F g-1 for untreated biochar. This enhancement of the charge storage capacity is attributed to the creation of a broad distribution in pore size and a larger surface area. The plasma activation mechanisms in terms of the evolution of the biochar surface and microstructure are further discussed.

  12. Instabilities in a capacitively coupled oxygen plasma

    SciTech Connect

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

    2015-04-15

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

  13. Instabilities in a capacitively coupled oxygen plasma

    NASA Astrophysics Data System (ADS)

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

    2015-04-01

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

  14. Phenol Decomposition Process by Pulsed-discharge Plasma above a Water Surface in Oxygen and Argon Atmosphere

    NASA Astrophysics Data System (ADS)

    Shiota, Haruki; Itabashi, Hideyuki; Satoh, Kohki; Itoh, Hidenori

    By-products from phenol by the exposure of pulsed-discharge plasma above a phenol aqueous solution are investigated by gas chromatography mass spectrometry, and the decomposition process of phenol is deduced. When Ar is used as a background gas, catechol, hydroquinone and 4-hydroxy-2-cyclohexene-1-on are produced, and no O3 is detected; therefore, active species such as OH, O, HO2, H2O2, which are produced from H2O in the discharge, can convert phenol into those by-products. When O2 is used as a background gas, formic acid, maleic acid, succinic acid and 4,6-dihydroxy-2,4-hexadienoic acid are produced in addition to catechol and hydroquinone. O3 is produced in the discharge plasma, so that phenol is probably decomposed into 4,6-dihydroxy-2,4-hexadienoic acid by 1,3-dipolar addition reaction with O3, and then 4,6-dihydroxy-2,4-hexadienoic acid can be decomposed into formic acid, maleic acid and succinic acid by 1,3-dipolar addition reaction with O3.

  15. Plasma Processing Of Hydrocarbon

    SciTech Connect

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

    2007-05-01

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

  16. Influence of Oxygenated Compounds on Reaction Products in a Microwave Plasma Methane Pyrolysis Assembly for Post-Processing of Sabatier Methane

    NASA Technical Reports Server (NTRS)

    Mansell, J. Matthew; Abney, Morgan B.

    2012-01-01

    The state-of-the-art Carbon Dioxide Reduction Assembly (CRA) was delivered to the International Space Station (ISS) in April 2010. The system is designed to accept carbon dioxide from the Carbon Dioxide Removal Assembly and hydrogen from the Oxygen Generation Assembly. The two gases are reacted in the CRA in a Sabatier reactor to produce water and methane. Venting of methane results in an oxygen resupply requirement of about 378 lbs per crew member per year. If the oxygen is supplied as water, the total weight for resupply is about 476 lb per crew member per year. For long-term missions beyond low Earth orbit, during which resupply capabilities will be further limited, recovery of hydrogen from methane is highly desirable. For this purpose, NASA is pursuing development of a Plasma Pyrolysis Assembly (PPA) capable of recovering hydrogen from methane. Under certain conditions, water vapor and carbon dioxide (nominally intended to be separated from the CRA outlet stream) may be present in the PPA feed stream. Thus, testing was conducted in 2010 to determine the effect of these oxygenated compounds on PPA performance, particularly the effect of inlet carbon dioxide and water variations on the PPA product stream. This paper discusses the test set-up, analysis, and results of this testing.

  17. Influence of Oxygenated Compounds on Reaction Products in a Microwave Plasma Methane Pyrolysis Assembly for Post-Processing of Sabatier Methane

    NASA Technical Reports Server (NTRS)

    Mansell, J. Matthew; Abney, Morgan B.; Miller, Lee A.

    2011-01-01

    The state-of-the-art Carbon Dioxide Reduction Assembly (CRA) was delivered to the International Space Station (ISS) in April 2010. The system is designed to accept carbon dioxide from the Carbon Dioxide Removal Assembly and hydrogen from the Oxygen Generation Assembly. The two gases are reacted in the CRA in a Sabatier reactor to produce water and methane. Venting of methane results in an oxygen resupply requirement of about 378 lbs per crew member per year. If the oxygen is supplied as water, the total weight for resupply is about 476 lb per crew member per year. For long-term missions beyond low Earth orbit, during which resupply capabilities will be further limited, recovery of hydrogen from methane is highly desirable. For this purpose, NASA is pursuing development of a Plasma Pyrolysis Assembly (PPA) capable of recovering hydrogen from methane. Under certain conditions, water vapor and carbon dioxide (nominally intended to be separated from the CRA outlet stream) may be present in the PPA feed stream. Thus, testing was conducted in 2010 to determine the effect of these "oxygenated" compounds on PPA performance, particularly the effect of inlet carbon dioxide and water variations on the PPA product stream. This paper discusses the test set-up, analysis, and results of this testing

  18. Band gap effects of hexagonal boron nitride using oxygen plasma

    SciTech Connect

    Sevak Singh, Ram; Leong Chow, Wai; Yingjie Tay, Roland; Hon Tsang, Siu; Mallick, Govind; Tong Teo, Edwin Hang

    2014-04-21

    Tuning of band gap of hexagonal boron nitride (h-BN) has been a challenging problem due to its inherent chemical stability and inertness. In this work, we report the changes in band gaps in a few layers of chemical vapor deposition processed as-grown h-BN using a simple oxygen plasma treatment. Optical absorption spectra show a trend of band gap narrowing monotonically from 6 eV of pristine h-BN to 4.31 eV when exposed to oxygen plasma for 12 s. The narrowing of band gap causes the reduction in electrical resistance by ∼100 fold. The x-ray photoelectron spectroscopy results of plasma treated hexagonal boron nitride surface show the predominant doping of oxygen for the nitrogen vacancy. Energy sub-band formations inside the band gap of h-BN, due to the incorporation of oxygen dopants, cause a red shift in absorption edge corresponding to the band gap narrowing.

  19. Oxygen Plasma Interactions with Molybdenum: Formation of Volatile Molybdenum Oxides

    NASA Astrophysics Data System (ADS)

    Saburi, Tei; Murata, Hirotoshi; Suzuki, Tatsuya; Fujii, Yasuhiko; Kiuchi, Kiyoshi

    The oxidation of molybdenum by oxygen plasma was studied. The oxygen plasma was discharged by helicon wave at the frequency of 18.1 MHz and at the power of 200W. The weight change of molybdenum in oxygen plasma was measured at 400 °C and at oxygen pressure of 5 Pa. The specimen was found to be oxidized and to lose it's weight drastically with the oxygen plasma, while the weight change of the specimen in the oxidation without plasma was not observed under the same conditions. The energetic species of oxygen atoms generated by rf plasma is regarded to accelerate the oxidation of molybdenum and the oxidation leads to the formation of volatile molybdenum trioxide at the surface.

  20. Atmospheric oxygen plasma activation of silicon (100) surfaces

    SciTech Connect

    Habib, Sara B.; Gonzalez, Eleazar II; Hicks, Robert F.

    2010-05-15

    Silicon (100) surfaces were converted to a hydrophilic state with a water contact angle of <5 deg. by treatment with a radio frequency, atmospheric pressure helium, and oxygen plasma. A 2 in. wide plasma beam, operating at 250 W, 1.0 l/min O{sub 2}, 30 l/min He, and a source-to-sample distance of 3{+-}0.1 mm, was scanned over the sample at 100{+-}2 mm/s. Plasma oxidation of HF-etched silicon caused the dispersive component of the surface energy to decrease from 55.1 to 25.8 dyn/cm, whereas the polar component of the surface energy increased from 0.3 to 42.1 dyn/cm. X-ray photoelectron spectroscopy revealed that the treatment generated a monolayer of covalently bonded oxygen on the Si(100) surface 0.15{+-}0.10 nm thick. The surface oxidation kinetics have been measured by monitoring the change in water contact angle with treatment time, and are consistent with a process that is limited by the mass transfer of ground-state oxygen atoms to the silicon surface.

  1. Pulsed RF Plasma Source for Materials Processing

    NASA Astrophysics Data System (ADS)

    Nasiruddin, Abutaher Mohammad

    A pulsed rf plasma source was evaluated for materials processing. A pulsed rf discharge of carbon tetrafluoride (CF_4), sulfur hexafluoride (SF _6), oxygen (O_2), or acetylene (C_2H_2 ) created the plasmas. The frequency and duration of the rf discharge were about 290 kHz and 30 musec, respectively. The repetition rate was 1 discharge per minute. Plasma diagnostics included Langmuir probes, a photodiode dectector, an optical multichannel analyzer (OMA), and a microwave interferometer. Langmuir probe measurements showed that at a position 67 cm away from the rf coil, CF_4 plasma arrived in separate packets. Plasma densities and electron temperatures at this position were in the range 4 times 10^{11} cm ^{-3} to 1.8 times 10^{13} cm ^{-3} and 2 eV to 8.3 eV, respectively. The OMA measurements identified neutral atomic fluorine in the CF_4 plasma and neutral atomic oxygen in the O_2 plasma. A plasma slab model of the microwave interferometer was applied to predict the interferometer response. The measured response was found to be almost identical to the predicted response. The influence of different reactor parameters on plasma parameters was studied. Metal barriers of different geometry were used to control the ratio of charged particles to atomic neutrals in the plasma chamber. Four plasma structures were identified: precursor plasma, shock induced plasma, driver plasma, and delayed glow plasma. Pulsed CF _4 and SF_6 plasmas were used to etch silicon dioxide (SiO_2 ) grown on silicon wafers. The SF_6 plasma etched SiO_2 at a rate of about 0.71 A per discharge and the CF_4 plasma deposited a non-uniform film (possibly polymer) instead of etching. The C_2H _2 plasma deposited plasma polymerized acetylene on a KBr pellet with a deposition rate of 127 A per discharge. An FT-IR spectrum of the deposited film showed that carbon -to-carbon double bonds as well as carbon-to-hydrogen bonds were present. This device can be used in plasma assisted deposition and/or synthesis

  2. Process Sprays Uniforms Plasma Coatings

    NASA Technical Reports Server (NTRS)

    Sliney, H. E.; Jacobson, T. P.; Walther, G. C.; Nakamura, H. H.

    1983-01-01

    Composite-powder processing procedure developed along with plasma-spray parameters to achieve homogeneous, well-bonded, low-porosity, self-lubricating coatings. Multicomponent plasma coatings are applied without segretation of components.

  3. Cleaning Carbon Nanotubes by Use of Mild Oxygen Plasmas

    NASA Technical Reports Server (NTRS)

    Petkov, Mihail

    2006-01-01

    Experiments have shown that it is feasible to use oxygen radicals (specifically, monatomic oxygen) from mild oxygen plasmas to remove organic contaminants and chemical fabrication residues from the surfaces of carbon nanotubes (CNTs) and metal/CNT interfaces. A capability for such cleaning is essential to the manufacture of reproducible CNT-based electronic devices. The use of oxygen radicals to clean surfaces of other materials is fairly well established. However, previously, cleaning of CNTs and of graphite by use of oxygen plasmas had not been attempted because both of these forms of carbon were known to be vulnerable to destruction by oxygen plasmas. The key to success of the present technique is, apparently, to ensure that the plasma is mild . that is to say, that the kinetic and internal energies of the oxygen radicals in the plasma are as low as possible. The plasma oxygen-radical source used in the experiments was a commercial one marketed for use in removing hydrocarbons and other organic contaminants from vacuum systems and from electron microscopes and other objects placed inside vacuum systems. In use, the source is installed in a vacuum system and air is leaked into the system at such a rate as to maintain a background pressure of .0.56 torr (.75 Pa). In the source, oxygen from the air is decomposed into monatomic oxygen by radio-frequency excitation of a resonance of the O2 molecule (N2 is not affected). Hence, what is produced is a mild (non-energetic) oxygen plasma. The oxygen radicals are transported along with the air molecules in the flow created by the vacuum pump. In the experiments, exposure to the oxygen plasma in this system was shown to remove organic contaminants and chemical fabrication residues from several specimens. Many high-magnification scanning electron microscope (SEM) images of CNTs were taken before and after exposure to the oxygen plasma. As in the example shown in the figure, none of these images showed evidence of degradation

  4. Modeling and simulation of plasma processing equipment

    NASA Astrophysics Data System (ADS)

    Kim, Heon Chang

    Currently plasma processing technology is utilized in a wide range of applications including advanced Integrated Circuit (IC) fabrication. Traditionally, plasma processing equipments have been empirically designed and optimized at great expense of development time and cost. This research proposes the development of a first principle based, multidimensional plasma process simulator with the aim of enhancing the equipment design procedure. The proposed simulator accounts for nonlinear interactions among various plasma chemistry and physics, neutral chemistry and transport, and dust transport phenomena. A three moment modeling approach is employed that shows good predictive capabilities at reasonable computational expense. For numerical efficiency, various versions of explicit and implicit Essentially Non- Oscillatory (ENO) algorithms are employed. For the rapid evaluation of time-periodic steady-state solutions, a feedback control approach is employed. Two dimensional simulation results of capacitively coupled rf plasmas show that ion bombardment uniformity can be improved through simulation based design of the plasma process. Through self-consistent simulations of an rf triode, it is also shown that effects of secondary rf voltage and frequency on ion bombardment energy can be accurately captured. These results prove that scaling relations among important process variables can be identified through the three moment modeling and simulation approach. Through coupling of the plasma model with a neutral chemistry and transport model, spatiotemporal distributions of both charged and uncharged species, including metastables, are predicted for an oxygen plasma. Furthermore, simulation results also verify the existence of a double layer in this electronegative plasma. Through Lagrangian simulation of dust in a plasma reactor, it is shown that small particles are accumulate near the center and the radial sheath boundary depending on their initial positions while large

  5. Thermal plasma processing of materials

    SciTech Connect

    Pfender, E.; Heberlein, J.

    1992-02-01

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

  6. Long-distance oxygen plasma sterilization: Effects and mechanisms

    NASA Astrophysics Data System (ADS)

    Liu, Hongxia; Chen, Jierong; Yang, Liqing; Zhou, Yuan

    2008-01-01

    The distribution of electrons, ions and oxygen radicals in long-distance oxygen plasma and the germicidal effect (GE) of Escherichia coli on the surface of medical poly(tetrafluoroethylene) (PTFE) film were studied. The quantity of protein leakage and the production of lipid peroxide in bacterial suspension as well as the state of DNA were measured after sterilization to analyse the inactivation mechanisms. The results showed that the concentration of electrons and ions decreased rapidly with increasing the distance from the center of induction coil, which approximated to 0 at 30 cm, whereas the concentration of oxygen radicals reduced slowly, i.e. decreased 30% within 40 cm. GE value reached 3.42 in the active discharge zone (0 cm) and exceeded 3.32 within 40 cm when plasma treatment parameters were set as follows: plasma rf power at 100 W, treatment time at 60 s and oxygen flux at 40 cm 3/min. Fast etching action on cell membrane by electrons, ions and attacking polyunsaturation fatty acid (PUFA) in cell membrane by oxygen radicals are primary reasons of oxygen plasma sterilization in the active discharge and the afterglow zone, respectively. The GE of UV radiation in long-distance oxygen plasma is feebleness.

  7. [Study of plasma temperature measurements for oxygen discharge].

    PubMed

    Li, Liu-Cheng; Wang, Zeng-Qiang; Li, Gu-Fu; Duo, Li-Ping

    2011-10-01

    A radio-frequency discharge setup was constructed by two shell-shaped copper electrodes and a 30 cm long pyrex glass tube (i. d. = 1.65 cm) to examine the gas temperature of oxygen plasma in electric discharge oxygen iodine laser. The discharge was supplied by a 500 watt, 13.56 MHz radio-frequency power. The gas pressure in the discharge cavity was 1 330 Pa. The temperature of oxygen discharge plasma was measured by using the P branch of O2 (b, v = 0) rotational emission spectrum. Two methods were used to deduce the oxygen gas temperature. They are Boltzman plotting method and computer simulating spectrum method, respectively. Gauss fitting method was used to distinguish spectrum peaks for lower resolution spectrum. The spectrum peak area was used to characterize the optical emission intensity. The gas temperature of oxygen discharge plasma was obtained by Boltzmann plotting method. Alternatively, the optical emission spectrum was simulated by computer modeling with spectrometer slit function which was obtained by He-Ne laser. Consequently, the gas temperature of oxygen plasma was obtained by comparing the computer simulating spectrum and the experimentally observed spectrum according to the least square fitting rule. The measurement results with the two methods agree well. It was concluded that the simple optical technique can be used conveniently in the temperature diagnostics of oxygen radio-frequency discharge plasma. PMID:22250527

  8. Methane Post-Processing for Oxygen Loop Closure

    NASA Technical Reports Server (NTRS)

    Greenwood, Zachary W.; Abney, Morgan B.; Miller, Lee

    2016-01-01

    State-of-the-art United States Atmospheric Revitalization carbon dioxide (CO2) reduction is based on the Sabatier reaction process, which recovers approximately 50% of the oxygen (O2) from crew metabolic CO2. Oxygen recovery from carbon dioxide is constrained by the limited availability of reactant hydrogen. Post-processing of methane to recover hydrogen with the Umpqua Research Company Plasma Pyrolysis Assembly (PPA) has the potential to further close the Atmospheric Revitalization oxygen loop. The PPA decomposes methane into hydrogen and hydrocarbons, predominantly acetylene, and a small amount of solid carbon. The hydrogen must then be purified before it can be recycled for additional oxygen recovery. Long duration testing and evaluation of a four crew-member sized PPA and a discussion of hydrogen recycling system architectures are presented.

  9. Plasma characterization studies for materials processing

    SciTech Connect

    Pfender, E.; Heberlein, J.

    1995-12-31

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

  10. Reactive Plasma Etching of SiC in a Tetrafluoroethane / Oxygen Plasma

    NASA Astrophysics Data System (ADS)

    Galloway, Heather C.; Radican, Kevin P.; Donnelly, David; Koeck, Deborah C.

    2003-03-01

    The etch rate as a function of oxygen concentration was investigated in the RF magnetron plasma etching of SiC with tetrafluoroethane gas. The etch rate and surface roughness was measured with atomic force microscopy, while evidence of polymer deposition was analyzed with FTIR. Etch rates of > 10 nm/sec can be achieved with high selectivity with respect to an aluminum mask, near infinite selectivity with respect to silicon. This has also been found to be compatible with some low-k dielectric films. Tetrafluoroethane is of interest due to its high fluorine content. It is also a nontoxic, ozone friendly gas with a short atmospheric lifetime. The role of oxygen in the etching process will be discussed and this etching process will be compared to other SiC etches that have been previously reported

  11. Oxygen plasmas used to synthesize superoxides

    NASA Technical Reports Server (NTRS)

    Hollahan, J. R.; Wydeven, T.

    1972-01-01

    Production of alkali metal superoxides by interaction of molecular oxygen with alkali metals or their salts is discussed. Diagram of reactor to show components and operating principles is provided. Analysis of chemical reactions involved is developed.

  12. Transport processes in space plasmas

    SciTech Connect

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

    1997-08-01

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

  13. INTRODUCTION: Nonequilibrium Processes in Plasmas

    NASA Astrophysics Data System (ADS)

    Petrović, Zoran; Marić, Dragana; Malović, Gordana

    2009-07-01

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

  14. Atomic oxygen patterning from a biomedical needle-plasma source

    NASA Astrophysics Data System (ADS)

    Kelly, Seán; Turner, Miles M.

    2013-09-01

    A "plasma needle" is a cold plasma source operating at atmospheric pressure. Such sources interact strongly with living cells, but experimental studies on bacterial samples show that this interaction has a surprising pattern resulting in circular or annular killing structures. This paper presents numerical simulations showing that this pattern occurs because biologically active reactive oxygen and nitrogen species are produced dominantly where effluent from the plasma needle interacts with ambient air. A novel solution strategy is utilised coupling plasma produced neutral (uncharged) reactive species to the gas dynamics solving for steady state profiles at the treated biological surface. Numerical results are compared with experimental reports corroborating evidence for atomic oxygen as a key bactericidal species. Surface losses are considered for interaction of plasma produced reactants with reactive solid and liquid interfaces. Atomic oxygen surface reactions on a reactive solid surface with adsorption probabilities above 0.1 are shown to be limited by the flux of atomic oxygen from the plasma. Interaction of the source with an aqueous surface showed hydrogen peroxide as the dominant species at this interface.

  15. Atomic oxygen patterning from a biomedical needle-plasma source

    SciTech Connect

    Kelly, Seán; Turner, Miles M.

    2013-09-28

    A “plasma needle” is a cold plasma source operating at atmospheric pressure. Such sources interact strongly with living cells, but experimental studies on bacterial samples show that this interaction has a surprising pattern resulting in circular or annular killing structures. This paper presents numerical simulations showing that this pattern occurs because biologically active reactive oxygen and nitrogen species are produced dominantly where effluent from the plasma needle interacts with ambient air. A novel solution strategy is utilised coupling plasma produced neutral (uncharged) reactive species to the gas dynamics solving for steady state profiles at the treated biological surface. Numerical results are compared with experimental reports corroborating evidence for atomic oxygen as a key bactericidal species. Surface losses are considered for interaction of plasma produced reactants with reactive solid and liquid interfaces. Atomic oxygen surface reactions on a reactive solid surface with adsorption probabilities above 0.1 are shown to be limited by the flux of atomic oxygen from the plasma. Interaction of the source with an aqueous surface showed hydrogen peroxide as the dominant species at this interface.

  16. Recombination processes in ionised plasmas

    NASA Astrophysics Data System (ADS)

    Bastin, Robert

    The observational analysis of astrophysical plasmas relies on accurate calculations of the atomic processes involved. The recombination spectra of singly ionised oxygen (O il) and carbon (C il) present excellent tools for investigating regions such as planetary nebulae and H II regions. In this thesis, detailed treatments of the recombination processes of both O II and C II are presented. Using the R-matrix solution to the close coupling equations, I present the results of accurate photoionisation calculations. Bound state energy levels are determined and oscillator strengths calculated for both species. Recombination coefficients were evalu ated for low n and 1, for C II in LS-coupling, and 0 II in intermediate coupling, taking particular care to treat resonances effectively. Sample photoionisation cross-sections are presented for both species, and compared to previous work. A complete radiative-cascade model is treated for both species, in order to determine line emissivities under nebular conditions at a wide range of temperatures and densities. Collisional effects are treated for C II, along with, for the first time, the effects of high temperature dielectronic recombination, allowing the modelling of regions of much higher electron temperature than previous work. The O II calculations were performed under intermediate coupling for the first time, allowing the effects of non-statistical popula tions of the parent ion fine-structure levels and dielectronic recombination onto bound states within this fine-structure to be taken into account in line emissivities. Detailed comparison with previous theoretical work was made for both species. The application of the C II and 0 n recombination spectra to determining tempera ture and densities from the observed spectra of a number of ionised nebulae is considered. The potential for using the new recombination spectra as diagnostic tools to solve some of the key problems in the study of ionised nebulae is demonstrated.

  17. Sterilization Effect of Wet Oxygen Plasma in the Bubbling Method.

    PubMed

    Tamazawa, Kaoru; Shintani, Hideharu; Tamazawa, Yoshinori; Shimauchi, Hidetoshi

    2015-01-01

    A new low-temperature sterilization method to replace the ethylene oxide gas sterilization is needed. Strong bactericidal effects of OH and O2H radicals are well known. The purpose of this study was to evaluate the sterilization effect of wet oxygen ("O2+H2O") plasma in the bubbling method, confirming the effect of humidity. Sterility assurance was confirmed by using a biological indicator (Geobacillus stearothermophilus ATCC7953, Namsa, USA). One hundred and eight samples (10(5) spores/carrier) were divided into three groups of 36 in each for treatment with a different type of gas (O2, O2+H2O, Air+H2O). Plasma processing was conducted using a plasma ashing apparatus (13.56 MHz, PACK-3(®), Y. A. C., Japan) under various gas pressures (13, 25, 50 Pa) and gas flows (50, 100, 200 sccm). Fixed plasma treatment parameters were power at 150 W, temperature of 60 ℃, treatment time of 10 min. The samples after treatment were incubated in trypticase soy broth at 58 ℃ for 72 h. The negative culture rate in the "O2+H2O" group was significantly (Mantel-Haenszel procedure, p<0.001) higher than in the other gas groups. It is suggested that the significant sterilization effect of the "O2+H2O" group depends on the bubbling method which is the method of introducing vapor into the chamber. The bubbling method seems able to generate OH and O2H radicals in a stable way. PMID:26699857

  18. Material Compatibility of Medical Sterilizer Using Oxygen Plasma

    NASA Astrophysics Data System (ADS)

    Tanaka, Hiroshi; Ono, Reoto; Hayashi, Nobuya; Hanada, Yasushi; Noda, Minoru; Goto, Masaaki

    2015-09-01

    Material compatibility of oxygen plasma sterilizer is investigated comparing with hydrogen peroxide (H2O2) sterilizers and a gaseous H2O2 sterilizer. Organic materials such as ABS, PE, PP, and PET are used as sample materials, and are irradiated by active oxygen species produced in oxygen plasma. After plasma irradiation, surface of the sample materials is observed using a scanning electron microscope and FTIR spectroscopy. Strengths of the organic materials are evaluated by the tension test. Also, H2O2 plasma sterilizer and a gaseous H2O2 sterilizer those are commercially available are utilized to compare the material compatibility, especially organic compounds. The ABS resin becomes slightly soft after irradiation by both plasmas and gaseous H2O2. Also, PET material becomes soften by each sterilization treatment. Decrease of peak heights of CH around 1200 and 1730 cm-1 and increase of that of OH at 3300 cm-1 in FTIR spectra indicates the oxidation of ABS resin by both plasma and gaseous H2O2. In the case of PET material, treatment by the plasma has not modified chemical composition but changed the crystal structure. The gaseous H2O2 is completely friendly for the PET material.

  19. Reactive Plasma Etching of SiC in a Tetrafluoroethane / Oxygen Plasma

    NASA Astrophysics Data System (ADS)

    McDonald, James S.; Radican, Kevin; Botello, Eric; Koeck, Deborah C.; Donnelly, David; Geerts, Wilhelmus; Spencer, Gregory; Galloway, Heather C.

    2003-10-01

    Fabrication of waveguides for electrical characterization of dielectric thin films requires a method of etching SiC and SiCN. A method of RF plasma etching was developed to ensure proper ground contact between the substrate and the ground lines. A constant flow of HFC 134a was investigated as compared to various oxygen flow rates, in order to determine the right mixture of HFC 134a and O_2, and the respective etch rate. This presentation will describe the method and techniques that were implemented using a magnetron gun attached to an RF network as a plasma source and a mixture of tetrafluoroethane or HFC 134a and O2 as the process gas.

  20. Electron-vibration relaxation in oxygen plasmas

    NASA Astrophysics Data System (ADS)

    Laporta, V.; Heritier, K. L.; Panesi, M.

    2016-06-01

    An ideal chemical reactor model is used to study the vibrational relaxation of oxygen molecules in their ground electronic state, X3 Σg-, in presence of free electrons. The model accounts for vibrational non-equilibrium between the translational energy mode of the gas and the vibrational energy mode of individual molecules. The vibrational levels of the molecules are treated as separate species, allowing for non-Boltzmann distributions of their population. The electron and vibrational temperatures are varied in the range [0-20,000] K. Numerical results show a fast energy transfer between oxygen molecules and free electron, which causes strong deviation of the vibrational distribution function from Boltzmann distribution, both in heating and cooling conditions. Comparison with Landau-Teller model is considered showing a good agreement for electron temperature range [2000-12,000] K. Finally analytical fit of the vibrational relaxation time is given.

  1. Stable processing with unstable plasmas?

    NASA Astrophysics Data System (ADS)

    Benjamin, Neil

    2004-09-01

    Plasmas are employed for materials processing over a very wide range of conditions. For typical etch applications, these include plasmas generated in various ways with RF at various frequencies and power levels ranging from 100W up to 10000W. Mixed gas chemistries are used, at pressures ranging from mTorr to Torr, with multiple, often electron-attaching species present in significant proportions. These complex conditions are typically produced in production reactors that are hardly optimal for diagnostic access, so this is not a recipe for a quiescent lab plasma that may be conveniently studied. Inevitably a range of plasma instabilities and other unstable conditions may be encountered, often without immediate detection, as one spans the operating space. These unstable conditions may range from internal well known linear and quasi-linear plasma instabilities1, 2 to gross non-linear relaxation oscillations3, 4, 5, parametric drifts and even plasma extinguishment. Many of these phenomena involve strong interactions with the materials being processed and the external hardware that supports the reactor module operation. We will discuss certain questions: how may one observe such conditions (if you can't see it, does it matter from the processing perspective?); is it advisable to continue processing regardless; what might the consequences be, good or bad, and how they may be controlled6? 1) T. H. Stix, Waves in Plasmas, American Institute of Physics, New York (1992), and The Theory of Plasma Waves, McGraw-Hill (1962). 2) N. Krall and A. Trivelpiece, Principles of Plasma Physics, McGraw-Hill (1973). 3) M. Tuszewski, J. App. Phys., 79 8967 (1996) 4) M. A. Lieberman et. al., Appl. Phys. Lett. 75, 3617 (1999) 5) A. M. Marakhtanov et..al., J. Vac. Sci. Tech. A, 21 1864 (2003) and references therein. 6) D.L.Goodman and N. M. P. Benjamin, J. Phys. D, 36 2845 (2003).

  2. Oxygen impurity radiation from Tokamak-like plasmas

    NASA Technical Reports Server (NTRS)

    Rogerson, J. E.; Davis, J.; Jacobs, V. L.

    1977-01-01

    We have constructed a nonhydrodynamic coronal model for calculating radiation from impurity atoms in a heated plasma. Some recent developments in the calculation of dielectronic recombination rate coefficients and collisional excitation rate coefficients are included. The model is applied to oxygen impurity radiation during the first few milliseconds of a TFR Tokamak plasma discharge, and good agreement with experimental results is obtained. Estimates of total line and continuum radiation from the oxygen impurity are given. It is shown that impurity radiation represents a considerable energy loss.

  3. Oxide growth on silicides in oxygen plasma

    NASA Astrophysics Data System (ADS)

    Climent, A.; Enard, J. P.; Lavernhe, B.; Perriere, J.; Straboni, A.; Vuillermoz, B.; Levy, D.

    We have shown the possibility of growing thick oxide films on refractory metal silicides by plasma oxidation in the 500-900°C temperature range. Thin layers of Si-rich silicides TiSi x and WSi y ( x, y > 2) deposited onto Si or SiO 2 by cosputtering have been oxidized in and RF plasma at floating potential. The oxide growth rate, composition and thickness, and the depth distribution of cations were determined by the complementary use of nuclear reaction analysis and RBS. We have found that silicon in excess in the films diffuses through the silicide towards the surface to form a SiO 2 passivating overlayer. The Si oxide growth rate is diffusion limited, while for long treatment oxidation of the silicide itself occurs with the formation of an oxide mixture (metal oxide and SiO 2).

  4. Plasma Processing of Advanced Materials

    SciTech Connect

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

    2005-02-28

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

  5. Modeling of Plasma Spray Processes

    NASA Astrophysics Data System (ADS)

    Chang, Chong H.

    1996-10-01

    A comprehensive computational model for thermal plasma processes is being developed with sufficient generality and flexibility to apply to a wide variety of present and proposed plasma processing concepts and devices. In our model for gas-particle flows, the gas is represented as a continuous multicomponent chemically reacting gas with temperature-dependent thermodynamic and transport properties. Ions and electrons are considered as separate components or species of the mixture, while ionization and dissociation reactions are treated as chemical reactions. Entrained particles interacting with the plasma are represented by a stochastic particle model in which the velocities, temperatures, sizes, and other characteristics of typical particles are computed simultaneously with the plasma flow. The model in its present form can simulate particle injection, heating, and melting, but not evaporation and condensation. This model is embodied in the LAVA computer code, which has previously been applied to simulate plasma spraying, mixing and demixing of plasma gases, and departures from chemical (ionization/dissociation), thermal, and excitation equilibrium in plasmas. A transient simulation has been performed of stainless steel particles injected into a swirling high-velocity nitrogen-hydrogen plasma jet in air under typical operating conditions for a newly developed high-velocity high-power (HVHP) torch, which produces plasma jets with peak velocities in excess of 3000 m/s. The calculational results show that strong departures from ionization and dissociation equilibrium develop in the downstream region as the chemical reactions freeze out at lower temperatures. The calculational results also show good agreement with experimental data on particle temperature, velocity, and spray pattern, together with important statistical effects associated with distributions in particle properties and injection conditions. This work was performed under the auspices of the U. S

  6. Treatment of enterococcus faecalis bacteria by a helium atmospheric cold plasma brush with oxygen addition

    SciTech Connect

    Chen Wei; Huang Jun; Wang Xingquan; Lv Guohua; Zhang Guoping; Du Ning; Liu Xiaodi; Guo Lihong; Yang Size

    2012-07-01

    An atmospheric cold plasma brush suitable for large area and low-temperature plasma-based sterilization is designed. Results demonstrate that the He/O{sub 2} plasma more effectively kills Enterococcus faecalis than the pure He plasma. In addition, the sterilization efficiency values of the He/O{sub 2} plasma depend on the oxygen fraction in Helium gas. The atmospheric cold plasma brush using a proper ratio of He/O{sub 2} (2.5%) reaches the optimum sterilization efficiency. After plasma treatment, the cell structure and morphology changes can be observed by the scanning electron microscopy. Optical emission measurements indicate that reactive species such as O and OH play a significant role in the sterilization process.

  7. Treatment of enterococcus faecalis bacteria by a helium atmospheric cold plasma brush with oxygen addition

    NASA Astrophysics Data System (ADS)

    Chen, Wei; Huang, Jun; Du, Ning; Liu, Xiao-Di; Wang, Xing-Quan; Lv, Guo-Hua; Zhang, Guo-Ping; Guo, Li-Hong; Yang, Si-Ze

    2012-07-01

    An atmospheric cold plasma brush suitable for large area and low-temperature plasma-based sterilization is designed. Results demonstrate that the He/O2 plasma more effectively kills Enterococcus faecalis than the pure He plasma. In addition, the sterilization efficiency values of the He/O2 plasma depend on the oxygen fraction in Helium gas. The atmospheric cold plasma brush using a proper ratio of He/O2 (2.5%) reaches the optimum sterilization efficiency. After plasma treatment, the cell structure and morphology changes can be observed by the scanning electron microscopy. Optical emission measurements indicate that reactive species such as O and OH play a significant role in the sterilization process.

  8. Oxygen transport in the internal xenon plasma of a dispenser hollow cathode

    NASA Astrophysics Data System (ADS)

    Capece, Angela M.; Polk, James E.; Mikellides, Ioannis G.; Shepherd, Joseph E.

    2014-04-01

    Reactive gases such as oxygen and water vapor modify the surface morphology of BaO dispenser cathodes and degrade the electron emission properties. For vacuum cathodes operating at fixed temperature, the emission current drops rapidly when oxygen adsorbs on top of the low work function surface. Previous experiments have shown that plasma cathodes are more resistant to oxygen poisoning and can operate with O2 partial pressures one to two orders of magnitude higher than vacuum cathodes before the onset of poisoning occurs. Plasma cathodes used for electric thrusters are typically operated with xenon; however, gas phase barium, oxygen, and tungsten species may be found in small concentrations. The densities of these minor species are small compared with the plasma density, and thus, their presence in the discharge does not significantly alter the xenon plasma parameters. It is important, however, to consider the transport of these minor species as they may deposit on the emitter surface and affect the electron emission properties. In this work, we present the results of a material transport model used to predict oxygen fluxes to the cathode surface by solving the species conservation equations in a cathode with a 2.25 mm diameter orifice operated at a discharge current of 15 A, a Xe flow rate of 3.7 sccm, and 100 ppm of O2. The dominant ionization process for O2 is resonant charge exchange with xenon ions. Ba is effectively recycled in the plasma; however, BaO and O2 are not. The model shows that the oxygen flux to the surface is not diffusion-limited; therefore, the high resistance to oxygen poisoning observed in plasma cathodes likely results from surface processes not considered here.

  9. Oxygen transport in the internal xenon plasma of a dispenser hollow cathode

    SciTech Connect

    Capece, Angela M. Shepherd, Joseph E.; Polk, James E.; Mikellides, Ioannis G.

    2014-04-21

    Reactive gases such as oxygen and water vapor modify the surface morphology of BaO dispenser cathodes and degrade the electron emission properties. For vacuum cathodes operating at fixed temperature, the emission current drops rapidly when oxygen adsorbs on top of the low work function surface. Previous experiments have shown that plasma cathodes are more resistant to oxygen poisoning and can operate with O{sub 2} partial pressures one to two orders of magnitude higher than vacuum cathodes before the onset of poisoning occurs. Plasma cathodes used for electric thrusters are typically operated with xenon; however, gas phase barium, oxygen, and tungsten species may be found in small concentrations. The densities of these minor species are small compared with the plasma density, and thus, their presence in the discharge does not significantly alter the xenon plasma parameters. It is important, however, to consider the transport of these minor species as they may deposit on the emitter surface and affect the electron emission properties. In this work, we present the results of a material transport model used to predict oxygen fluxes to the cathode surface by solving the species conservation equations in a cathode with a 2.25 mm diameter orifice operated at a discharge current of 15 A, a Xe flow rate of 3.7 sccm, and 100 ppm of O{sub 2}. The dominant ionization process for O{sub 2} is resonant charge exchange with xenon ions. Ba is effectively recycled in the plasma; however, BaO and O{sub 2} are not. The model shows that the oxygen flux to the surface is not diffusion-limited; therefore, the high resistance to oxygen poisoning observed in plasma cathodes likely results from surface processes not considered here.

  10. Minimizing permeability of PET substrates using Oxygen plasma treatment

    NASA Astrophysics Data System (ADS)

    Sanaee, Z.; Mohajerzadeh, S.; Zand, K.; Gard, F. S.; Pajouhi, H.

    2011-01-01

    Surface plasma treatment in a reactive ion etching system is used to observe a considerable decrease in permeability of polyethylene terephthalate to gases. The effects of oxygen plasma on the surface properties and morphology of PET polymers are investigated by scanning electron microscopy (SEM), x-ray photo-electron spectroscopy (XPS) and atomic force microscopy (AFM). In addition, the optical transmission properties of the treated samples have been investigated corroborating the findings of SEM and AFM analyses. Moreover, the penetration of air through the treated substrates was investigated using a vacuum test. The treated PET substrates can be used to realize flexible plasma display panels.

  11. Semiconductor Industry Plasma Processing Needs

    NASA Astrophysics Data System (ADS)

    Wise, Richard; Panda, Siddhartha; Yan, Wendy

    2003-10-01

    The plasma requirements of dry etch equipment used for advanced semiconductor process development and low cost semiconductor manufacturing are reviewed. Introduction of ArF (193nm) photolithography has resulted in increased demands on resist selectivity, increased sensitivity to plasma induced or exacerbated line edge roughness, and the introduction of novel hard and soft mask schemes. State of the art plasma processing chambers must be able to deliver low DC bias due to line edge roughness requirements with adequate ion/radical density to prevent loss of critical dimension control in deep features. These same systems may be required to operate in a high DC bias, low plasma density regime to achieve adequate etch rate on different films, and in many cases the system must be able to switch between low and high DC bias modes. The acceptable plasma density is limited by that necessary to provide adequate production of passivation agents necessary to achieve selectivity to ArF photoresists. Further limits on plasma density may be needed due to device and etch profile sensitivity to differential charging. The allowable DC bias may be limited to avoid damage to shallow implanted regions and thin gate. Decreases in gate length have increased sensitivity to non-anisotropic profiles, which in turn requires a minimum of DC bias to provide anisotropy. Particle sensitivity has resulted in a migration toward integrated plasma processing, putting additional demands on the stability and flexibility of the plasma equipment. State of the art plasma tooling must be capable of operating over a wide range of plasma densities, delivering both high and low DC bias, and provide RF stability over a wide range of wafer/chamber impedances. The increased uniformity requirements of 300 mm tools requires the anode and cathode potential be uniformly distributed over the entire surface, and that the plasma generation be as uniform as possible. Extended wet clean cycles have driven the need for

  12. Oxygen production processes on the Moon: An overview

    NASA Technical Reports Server (NTRS)

    Taylor, Lawrence A.; Carrier, W. David, III

    1991-01-01

    The production of oxygen on the Moon utilizing indigenous material is paramount to a successful lunar colonization. Several processes were put forth to accomplish this. The lunar liquid oxygen (LLOX) generation schemes which have received the most study to date are those involving: (1) the reduction of ilmenite (FeTiO3) by H2, C, CO, CH4, CO-Cl2 plasma; (2) magma electrolysis, both unadulterated and fluoride-fluxed, and (3) several others, including carbo-chlorination, HF acid leaching, fluorine extraction, magma oxidation, and vapor pyrolysis. The H2 reduction of ilmenite and magma electrolysis processes have received the most study to date. At this stage of development, they both appear feasible schemes with various pros and cons. However, all processes should be addressed at least at the onset of the considerations. It is ultimatley the energy requirements of the entire process, including the acquisition of feedstock, which will determine the mode of oxygen productions. There is an obvious need for considerably more experimentation and study. Some of these requisite studies are in progress, and several of the most studied and feasible processes for winning oxygen from lunar materials are reviewed.

  13. Antioxidants may Attenuate Plasma Erythropoietin Decline after Hyperbaric Oxygen Diving.

    PubMed

    Mutzbauer, T S; Schneider, M; Neubauer, B; Weiss, M; Tetzlaff, K

    2015-11-01

    According to previous studies, plasma erythropoietin (EPO) may decrease after hyperbaric oxygen exposure due to oxidative stress. It is hypothesized that the decrease of EPO can be attenuated by oxygen free radical scavengers.The aim of the present study was to evaluate whether EPO plasma levels can be influenced by oral application of vitamin C and E before repeated hyperbaric oxygen exposure during diving. 16 healthy male police task force divers performed 3 morning dives on oxygen within a regular diving schedule on 3 consecutive days. They were randomized into either the placebo group or the vitamin group, receiving 1 g ascorbic acid and 600 IU D-α-tocopherol orally 60 min before the dive. Blood samples for EPO measurement were taken on days 1, 2, and 3 at T1, T3 and T5 60 min before and at T2, T4 and T6 60 min after each dive, respectively. A moderate decrease of EPO was observed beginning at T3 until T6 in the placebo group. The EPO concentrations in the vitamin group did not show relevant variations compared to baseline. Radical scavenging vitamins C and D may counteract hyperbaric oxygen related mechanisms reducing EPO production in hyperbaric oxygen exposure during diving. PMID:26258821

  14. Novel Membranes and Processes for Oxygen Enrichment

    SciTech Connect

    Lin, Haiqing

    2011-11-15

    The overall goal of this project is to develop a membrane process that produces air containing 25-35% oxygen, at a cost of $25-40/ton of equivalent pure oxygen (EPO2). Oxygen-enriched air at such a low cost will allow existing air-fueled furnaces to be converted economically to oxygen-enriched furnaces, which in turn will improve the economic and energy efficiency of combustion processes significantly, and reduce the cost of CO{sub 2} capture and sequestration from flue gases throughout the U.S. manufacturing industries. During the 12-month Concept Definition project: We identified a series of perfluoropolymers (PFPs) with promising oxygen/nitrogen separation properties, which were successfully made into thin film composite membranes. The membranes showed oxygen permeance as high as 1,200 gpu and oxygen/nitrogen selectivity of 3.0, and the permeance and selectivity were stable over the time period tested (60 days). We successfully scaled up the production of high-flux PFP-based membranes, using MTR's commercial coaters. Two bench-scale spiral-wound modules with countercurrent designs were made and parametric tests were performed to understand the effect of feed flow rate and pressure, permeate pressure and sweep flow rate on the membrane module separation properties. At various operating conditions that modeled potential industrial operating conditions, the module separation properties were similar to the pure-gas separation properties in the membrane stamps. We also identified and synthesized new polymers [including polymers of intrinsic microporosity (PIMs) and polyimides] with higher oxygen/nitrogen selectivity (3.5-5.0) than the PFPs, and made these polymers into thin film composite membranes. However, these membranes were susceptible to severe aging; pure-gas permeance decreased nearly six-fold within two weeks, making them impractical for industrial applications of oxygen enrichment. We tested the effect of oxygen-enriched air on NO{sub x} emissions using a

  15. Method & apparatus for monitoring plasma processing operations

    DOEpatents

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

    2004-10-19

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

  16. Influence of the oxygen plasma parameters on the atomic layer deposition of titanium dioxide.

    PubMed

    Ratzsch, Stephan; Kley, Ernst-Bernhard; Tünnermann, Andreas; Szeghalmi, Adriana

    2015-01-16

    The influence of the oxygen plasma parameters on the morphology and optical properties of TiO2 thin films has been extensively analyzed in plasma enhanced atomic layer deposition (PEALD) processes. Crystalline aggregates with the anatase phase have been identified on the film surface at a low deposition temperature (down to 70 °C) under specific plasma conditions. Up to 70% surface coverage by anatase crystallites is obtained at low oxygen gas flow rates and high plasma power. The hillocks abundance is correlated with high ion flux and electron density and with the resulting enhanced ion bombardment of the surface. Altering the plasma conditions is an important parameter besides temperature to control the morphology of the titania film for specific applications such as photocatalysis or functional optical coatings. Specifically, photocatalytic titania coatings on polymer substrates could benefit of such low temperature PEALD processes with abundant anatase crystallites; whereas optical coatings require smooth, high refractive index titania as obtained with low plasma power and high oxygen flow rate. PMID:25525676

  17. Reaction mechanisms of oxygen plasma interaction with organosilicate low-k materials containing organic crosslinking groups

    SciTech Connect

    Chaudhari, Mrunalkumar; Du Jincheng

    2012-11-15

    Integration of low dielectric constant (k) materials such as organosilicate glasses (OSG) into microelectronic processing demands a better of understanding the plasma/OSG interactions during plasma etching and ashing of these materials, based on which low-k materials with higher radiation resistance and better mechanical behaviors can be developed and optimized plasma processing conditions can be introduced to ensure continued miniaturization of semiconductor devices. Introducing organic crosslinking (e.g., -CH{sub 2}-) in OSG has been shown to be an effective measure to improve the mechanical properties but their effect on plasma interaction is still not fully understood. In this paper, ab initio based molecular dynamics simulations have been employed to investigate the effect of the oxygen plasma on the carbon-bridged silicate networks in the OSG material. The results show that organic crosslinking in the Si-O-Si network leads to lower energy reaction pathways with atomic oxygen radicals that result in breakage of Si-CH{sub 2}-Si linkages instead of Si-CH{sub 3} bonds and, consequently, a decrease in carbon removal. The incorporation of organic crosslinking groups can thus improve the resistance to oxygen plasma damage of OSG and, together with better mechanical properties, can lead to the design of stronger low-k dielectric films.

  18. A modified sulfate process to lunar oxygen

    NASA Technical Reports Server (NTRS)

    Sullivan, Thomas A.

    1992-01-01

    A modified sulfate process which produces oxygen from iron oxide-bearing minerals in lunar soil is under development. Reaction rates of ilmenite in varying strength sulfuric acid have been determined. Quantitative conversion of ilmenite to ferrous sulfate was observed over a range of temperatures and concentrations. Data has also been developed on the calcination of by-product sulfates. System engineering for overall operability and simplicity has begun, suggesting that a process separating the digestion and sulfate dissolution steps may offer an optimum process.

  19. Cold plasma processing technology makes advances

    Technology Transfer Automated Retrieval System (TEKTRAN)

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

  20. Restructured graphene sheets embedded carbon film by oxygen plasma etching and its tribological properties

    NASA Astrophysics Data System (ADS)

    Guo, Meiling; Diao, Dongfeng; Yang, Lei; Fan, Xue

    2015-12-01

    An oxygen plasma etching technique was introduced for improving the tribological properties of the graphene sheets embedded carbon (GSEC) film in electron cyclotron resonance plasma processing system. The nanostructural changing in the film caused by oxygen plasma etching was examined by transmission electron microscope, Raman spectroscopy and X-ray photoelectron spectroscopy, showing that the 3 nm thick top surface layer was restructured with smaller graphene nanocrystallite size as well as higher sp3 bond fraction. The surface roughness, mechanical behavior and tribological properties of the original GSEC and oxygen plasma treated GSEC films were compared. The results indicated that after the oxygen plasma treatment, the average roughness decreased from 20.8 ± 1.1 nm to 1.9 ± 0.1 nm, the hardness increased from 2.3 ± 0.1 GPa to 2.9 ± 0.1 GPa, the nanoscratch depth decreased from 64.5 ± 5.4 nm to 9.9 ± 0.9 nm, and the wear life increased from 930 ± 390 cycles to more than 15,000 frictional cycles. The origin of the improved tribological behavior was ascribed to the 3 nm thick graphene nanocrystallite film. This finding can be expected for wide applications in nanoscale surface engineering.

  1. Sub millimeter absorption spectroscopy of oxygen containing fluorocarbon etching plasmas

    NASA Astrophysics Data System (ADS)

    Benck, Eric; Siegrist, Karen

    2004-09-01

    The role of oxygen in fluorocarbon etching plasmas is investigated using sub millimeter wavelength absorption spectroscopy. The plasmas were created in a specially modified capacitively coupled Gaseous Electronics Conference (GEC) Reference Reactor with a commercial electrostatic chuck. Photoresist and SiO2 blanket coated wafers were etched in C_4F_8/O_2/Ar, C_5F_8/O_2/Ar, and C_4F_6/O_2/Ar discharges. The absolute density of various radicals (CF, CF_2, CHF_3, COF_2, CO, etc.) were measured as a function of the percentage of oxygen in the feed gas mixture using a sub millimeter source based on a 48x frequency multiplication chain. These results are also compared with C_xF_y/O_2/Xe mixtures.

  2. Oxygen plasma resistant phosphine oxide containing imide/arylene copolymers

    NASA Technical Reports Server (NTRS)

    Jensen, Brian J.

    1993-01-01

    A series of oxygen plasma resistant imide/arylene ether copolymers were prepared by reacting anhydride-terminated poly(amide acids) and amine-terminated polyarylene ethers containing phosphine oxide units. Inherent viscosities for these copolymers ranged from 0.42 to 0.80 dL/g. After curing, the resulting copolymers had glass transition temperatures ranging from 224 C to 228 C. Solution cast films of the block copolymers were tough and flexible with tensile strength, tensile moduli, and elongation at break up to 16.1 ksi, 439 ksi, and 23 percent, respectively at 25 C and 9.1 ksi, 308 ksi and 97 percent, respectively at 150 C. The copolymers show a significant improvement in resistance to oxygen plasma when compared to the commercial polyimide Kapton. The imide/arylene ether copolymers containing phosphine oxide units are suitable as coatings, films, adhesives, and composite matrices.

  3. The plasma hearth process: Process residuals characterization

    SciTech Connect

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

    1994-12-31

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

  4. Plasma hearth process demonstration project

    SciTech Connect

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

    1995-12-31

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

  5. Hydrogen and oxygen trapping and retention in stainless steel and graphite materials irradiated in plasma

    NASA Astrophysics Data System (ADS)

    Begrambekov, L.; Ayrapetov, A.; Ermakov, V.; Kaplevsky, A.; Sadovsky, Ya.; Shigin, P.

    2013-11-01

    The paper presents the results of experimental investigation of energy and flux dependences of hydrogen isotopes and oxygen trapping in carbon materials (carbon fiber composite and pyrolitic graphite), and metals (stainless steel and nickel) under irradiation in the deuterium gas discharge plasma with and without oxygen addition. The dependence of hydrogen trapping on ion energy, ion current density, oxygen addition in deuterium plasma are presented and analyzed. The sorbed molecules, containing hydrogen atoms from the residual gas and deuterium atoms of the working gas are shown to be the important source of hydrogen trapping in both carbon based materials and stainless steel. Irradiation of the SS vacuum vessel with the neutrals or/and ions of (D2 + O2) plasma initiate the hydrogen diffusion from the vessel wall and H2, HD, D2O, HDO, H2O molecule formation on the wall surface. Trapping of the low energy plasma particles and the particles from the sorbed molecules as well as modification of working gas composition are considered as the processes provided at the expense of the potential energy of plasma particles with respect to the surface and occurred through their inelastic collisions with the surface. The hydrogen trapping occurred due to “potential” processes was named as “potential”, and in contrast the trapping of fast particles due to their kinetic energy was labeled as “kinetic”.

  6. Atomic Oxygen Energy in Low Frequency Hyperthermal Plasma Ashers

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.; Miller, Sharon K R.; Kneubel, Christian A.

    2014-01-01

    Experimental and analytical analysis of the atomic oxygen erosion of pyrolytic graphite as well as Monte Carlo computational modeling of the erosion of Kapton H (DuPont, Wilmington, DE) polyimide was performed to determine the hyperthermal energy of low frequency (30 to 35 kHz) plasma ashers operating on air. It was concluded that hyperthermal energies in the range of 0.3 to 0.9 eV are produced in the low frequency air plasmas which results in texturing similar to that in low Earth orbit (LEO). Monte Carlo computational modeling also indicated that such low energy directed ions are fully capable of producing the experimentally observed textured surfaces in low frequency plasmas.

  7. Reactive oxygen species controllable non-thermal helium plasmas for evaluation of plasmid DNA strand breaks

    NASA Astrophysics Data System (ADS)

    Young Kim, Jae; Lee, Dong-Hoon; Ballato, John; Cao, Weiguo; Kim, Sung-O.

    2012-11-01

    Non-thermal, oxygen-rich helium plasmas were investigated to achieve an enhanced reactive oxygen species concentration at low voltage driving conditions. A non-thermal plasma device was fabricated based on a theta-shaped tube, and its potential was investigated for use in topological alteration of plasmid DNA. The optical emission spectra of the plasma showed that the oxygen flow affected the plasma properties, even though an oxygen plasma was not produced. The plasmid DNA strand breaks became more significant with the addition of oxygen flow to the helium in a single hollow, theta-shaped tube with other experimental conditions being unchanged.

  8. Advanced plasma diagnostics for plasma processing

    NASA Astrophysics Data System (ADS)

    Malyshev, Mikhail Victorovich

    1999-10-01

    A new, non-intrusive, non-perturbing diagnostic method was developed that can be broadly applied to low pressure, weakly ionized plasmas and glow discharges-trace rare gases optical emission spectroscopy (TRG-OES). The method is based on a comparison of intensities of atomic emission from trace amounts of inert gases (He, Ne, Ar, Kr, and Xe) that are added to the discharge to intensities calculated from the theoretical model. The model assumes a Maxwellian electron energy distribution function (EEDF), computes the population of emitting levels both from the ground state and the metastable states of rare gases, and from the best fit between theory and experiment determines electron temperature (Te). Subject to conditions, TRG-OES can also yield electron density or its upper or lower limit. From the comparison of the emission from levels excited predominantly by high energy electrons to that excited by low energy electrons, information about the EEDF can be obtained. The use of TRG-OES also allows a traditionally qualitative actinometry technique (determination of concentration of radical species in plasma through optical emission) to become a precise quantitative method by including Te and rare gases metastables effects. A combination of TRG-OES, advanced actinometry, and Langmuir probe measurements was applied to several different plasma reactors and regimes of operation. Te measurements and experiments to correct excitation cross section were conducted in a laboratory helical resonator. Two chamber configuration of a commercial (Lam Research) metal etcher were studied to determine the effects of plasma parameters on plasma-induced damage. Two different methods (RF inductive coupling and ultra-high frequency coupling) for generating a plasma in a prototype reactor were also studied. Pulsed plasmas, a potential candidate to eliminate the plasma-induced damage to microelectronics devices that occurs in manufacturing due to differential charging of the wafer, have

  9. Comparison of CO2 and oxygen DC submerged thermal plasmas for decomposition of carboxylic acid in aqueous solution

    NASA Astrophysics Data System (ADS)

    Safa, S.; Hekmat-Ardakan, A.; Soucy, G.

    2014-11-01

    The feasibility of the carboxylic acid decomposition with two different direct current (DC) thermal plasma torches was investigated. An oxygen DC submerged thermal plasma torch and a newly designed submerged DC plasma torch operating with a mixture of carbon dioxide and methane (CO2/CH4) were used. Sebacic acid was selected as a representative of pollutants in the most wastewater produced by chemical process industries. The effect of different operational conditions including treatment time, the reactor pressure as well as the role of oxidizing agents such as (H2O2) were investigated on the decomposition rate of sebacic acid. Concentration of sebacic acid was quantified by Ion Chromatography/Mass Spectrometry (IC/MS). The oxygen plasma showed higher decomposition rate in basic medium. Adding H2O2 into aqueous solution enhanced the sebacic acid decomposition rate with the CO2/CH4 plasma up to the same decomposition rate of the oxygen plasma. Increasing the pressure also increased the decomposition rate for both plasmas with an increase twice higher for the CO2/CH4 plasma than that of the oxygen plasma. This work therefore presents the conditions in which these plasmas can provide the same decomposition rate for contaminants in aqueous solution.

  10. Treatment Characteristics of Polysaccharides and Endotoxin Using Oxygen Plasma Produced by RF Discharge

    SciTech Connect

    Kitazaki, Satoshi; Hayashi, Nobuya; Goto, Masaaki

    2010-10-13

    Treatment of polysaccharides and endotoxin were attempted using oxygen plasma produced by RF discharge. Oxygen radicals observed by optical light emission spectra are factors of decomposition of polysaccharides and endotoxin. Fourier transform infrared spectra indicate that most of chemical bonds in the polysaccharides are dissociated after irradiation of the oxygen plasma. Also, the decomposition rate of endotoxin was approximately 90% after irradiation of the oxygen plasma for 180 min.

  11. Reduced leakage in epitaxial BiFeO{sub 3} films following oxygen radio frequency plasma treatment

    SciTech Connect

    Kothari, Deepti; UGC-DAE Consortium for Scientific Research, University Campus, Khandwa Road, Indore 452 017 ; Upadhyay, Sanjay K.; Raghavendra Reddy, V.; Jariwala, C.; Raole, P. M.

    2013-06-07

    Epitaxial BiFeO{sub 3} (BFO) films were deposited using pulsed laser deposition method. The prepared films were characterized using x-ray diffraction, x-ray reflectivity, ferroelectric loop tracer, and leakage current measurements before and after oxygen plasma treatment. The leakage current of the films, a crucial parameter in device applications, is observed to be reduced by two orders of magnitude with oxygen plasma treatment at room temperature. P-E hysteresis loops were observed in oxygen plasma treated BFO films. The observed results indicate the usefulness of oxygen radio frequency plasma treatment (RF 13.56 MHz), which is an effective and low temperature processing technique, in such lossy ferroelectric thin films.

  12. A low-energy linear oxygen plasma source

    SciTech Connect

    Anders, Andre; Yushkov, Georgy Yu.

    2007-01-08

    A new version of a Constricted Plasma Source is described,characterized by all metal-ceramic construction, a linear slit exit of180 mm length, and cw-operation (typically 50 kHz) at an average power of1.5 kW. The plasma source is here operated with oxygen gas, producingstreaming plasma that contains mainly positive molecular and atomic ions,and to a much lesser degree, negative ions. The maximum total ion currentobtained was about 0.5 A. The fraction of atomic ions reached more than10 percent of all ions when the flow rate was less then 10 sccm O2,corresponding to a chamber pressure of about 0.5 Pa for the selectedpumping speed. The energy distribution functions of the different ionspecies were measured with a combinedmass spectrometer and energyanalyzer. The time-averaged distribution functions were broad and rangedfrom about 30eV to 90 eV at 200 kHz and higher frequencies, while theywere only several eV broad at 50 kHz and lower frequencies, with themaximum located at about 40 eV for the grounded anode case. This maximumwas shifted down to about 7 eV when the anode was floating, indicatingthe important role of the plasma potential for the ion energy for a givensubstrate potential. The source could be scaled to greater length and maybe useful for functionalization of surfaces and plasma-assisteddeposition of compound films.

  13. Plasma jet-induced tissue oxygenation: potentialities for new therapeutic strategies

    NASA Astrophysics Data System (ADS)

    Collet, G.; Robert, E.; Lenoir, A.; Vandamme, M.; Darny, T.; Dozias, S.; Kieda, C.; Pouvesle, J. M.

    2014-02-01

    The lack of oxygen is a major reason for the resistance of tumor cells to treatments such as radiotherapies. A large number of recent publications on non-thermal plasma applications in medicine report cell behavior modifications and modulation of soluble factors. This in vivo study tested whether such modifications can lead to vascular changes in response to plasma application. Two in situ optical-based methods were used simultaneously, in real time, to assess the effect of non-thermal plasma on tissue vasculature. Tissue oxygen partial pressure (pO2) was measured using a time-resolved luminescence-based optical probe, and the microvascular erythrocyte flow was determined by laser Doppler flowmetry. When plasma treatment was applied on mouse skin, a rapid pO2 increase (up to 4 times) was subcutaneously measured and correlated with blood flow improvement. Such short duration, i.e. 5 min, plasma-induced effects were shown to be locally restricted to the treated area and lasted over 120 min. Further investigations should elucidate the molecular mechanisms of these processes. However, improvement of oxygenation and perfusion open new opportunities for tumor treatments in combination with radiotherapy, and for tumor blood vessel normalization based strategies.

  14. The oxycoal process with cryogenic oxygen supply

    NASA Astrophysics Data System (ADS)

    Kather, Alfons; Scheffknecht, Günter

    2009-09-01

    Due to its large reserves, coal is expected to continue to play an important role in the future. However, specific and absolute CO2 emissions are among the highest when burning coal for power generation. Therefore, the capture of CO2 from power plants may contribute significantly in reducing global CO2 emissions. This review deals with the oxyfuel process, where pure oxygen is used for burning coal, resulting in a flue gas with high CO2 concentrations. After further conditioning, the highly concentrated CO2 is compressed and transported in the liquid state to, for example, geological storages. The enormous oxygen demand is generated in an air-separation unit by a cryogenic process, which is the only available state-of-the-art technology. The generation of oxygen and the purification and liquefaction of the CO2-enriched flue gas consumes significant auxiliary power. Therefore, the overall net efficiency is expected to be lowered by 8 to 12 percentage points, corresponding to a 21 to 36% increase in fuel consumption. Oxygen combustion is associated with higher temperatures compared with conventional air combustion. Both the fuel properties as well as limitations of steam and metal temperatures of the various heat exchanger sections of the steam generator require a moderation of the temperatures during combustion and in the subsequent heat-transfer sections. This is done by means of flue gas recirculation. The interdependencies among fuel properties, the amount and the temperature of the recycled flue gas, and the resulting oxygen concentration in the combustion atmosphere are investigated. Expected effects of the modified flue gas composition in comparison with the air-fired case are studied theoretically and experimentally. The different atmosphere resulting from oxygen-fired combustion gives rise to various questions related to firing, in particular, with regard to the combustion mechanism, pollutant reduction, the risk of corrosion, and the properties of the fly

  15. The oxycoal process with cryogenic oxygen supply.

    PubMed

    Kather, Alfons; Scheffknecht, Günter

    2009-09-01

    Due to its large reserves, coal is expected to continue to play an important role in the future. However, specific and absolute CO2 emissions are among the highest when burning coal for power generation. Therefore, the capture of CO2 from power plants may contribute significantly in reducing global CO2 emissions. This review deals with the oxyfuel process, where pure oxygen is used for burning coal, resulting in a flue gas with high CO2 concentrations. After further conditioning, the highly concentrated CO2 is compressed and transported in the liquid state to, for example, geological storages. The enormous oxygen demand is generated in an air-separation unit by a cryogenic process, which is the only available state-of-the-art technology. The generation of oxygen and the purification and liquefaction of the CO2-enriched flue gas consumes significant auxiliary power. Therefore, the overall net efficiency is expected to be lowered by 8 to 12 percentage points, corresponding to a 21 to 36% increase in fuel consumption. Oxygen combustion is associated with higher temperatures compared with conventional air combustion. Both the fuel properties as well as limitations of steam and metal temperatures of the various heat exchanger sections of the steam generator require a moderation of the temperatures during combustion and in the subsequent heat-transfer sections. This is done by means of flue gas recirculation. The interdependencies among fuel properties, the amount and the temperature of the recycled flue gas, and the resulting oxygen concentration in the combustion atmosphere are investigated. Expected effects of the modified flue gas composition in comparison with the air-fired case are studied theoretically and experimentally. The different atmosphere resulting from oxygen-fired combustion gives rise to various questions related to firing, in particular, with regard to the combustion mechanism, pollutant reduction, the risk of corrosion, and the properties of the fly

  16. Atomic processes for astrophysical plasmas

    NASA Astrophysics Data System (ADS)

    Badnell, N. R.; Del Zanna, G.; Fernández-Menchero, L.; Giunta, A. S.; Liang, G. Y.; Mason, H. E.; Storey, P. J.

    2016-05-01

    In this review we summarize the recent calculations and improvements of atomic data that we have carried out for the analysis of astrophysical spectroscopy within the atomic processes for astrophysical plasmas network. We briefly discuss the various methods used for the calculations, and highlight several issues that we have uncovered during such extensive work. We discuss the completeness and accuracy of the cross sections for ionic excitation by electron impact for the main isoelectronic sequences, which we have obtained with large-scale calculations. Given its astrophysical importance, we emphasize the work on iron. Some examples on the significant improvement that has been achieved over previous calculations are provided.

  17. Reactive Species Processes in Plasma-, Gas-, and Liquid-Phase

    NASA Astrophysics Data System (ADS)

    Reuter, Stephan; Winter, Joern; Hammer, Malte; Schmidt-Bleker, Ansgar; Iseni, Sylvain; Tresp, Helena; Dünnbier, Mario; Masur, Kai; Wende, Kristian; Weltmann, Klaus-Dieter

    2013-09-01

    Especially for the field of plasma medicine, plasmas interacting with liquids are of great interest for environmental, chemical, and biomedical applications. In this work we present optical diagnostics on atmospheric pressure plasma jets interacting with liquids. Combining the diagnostic results with numerical simulations yields an understanding of fundamental processes such as air species diffusion into the jet effluents or the influence on humidity. Especially for plasma treatment of physiological liquids in ambient air, atmospheric species play a key role. To achieve a desired reactive component output, the generation processes from these ambient air species are controlled. Plasma jets are characterized by planar laser induced fluorescence spectroscopy, by absorption and emission spectroscopy, and by flow simulations. With the gained knowledge we are able to tailor the reactive component composition and to influence plasma jet-liquid interaction. We show that reactive species generation within plasma treated liquid can be tuned and apply the findings to biological cells to investigate the effect of reactive oxygen and nitrogen species (RONS). The plasma treated liquids are investigated regarding their pH value, OH radicals, nitrate and nitrite, and H2O2 content. From the tailored plasma treatment a significant insight into the relevant transport processes in plasma treatment of liquids has been gained. Support by the German BMBF 03Z2DN11&12 is acknowledged.

  18. Sulfur recovery plant and process using oxygen

    SciTech Connect

    Palm, J.W.

    1989-07-18

    This patent describes a process for recovery of sulfur from a gaseous stream containing hydrogen sulfide. The process consists the steps of: introducing a thermal reaction mixture comprising the gaseous stream containing hydrogen sulfide, and an oxygen-enriched stream of air or pure oxygen into a combustion zone of a Claus furnace; combusting the thermal reaction mixture in the Claus furnace to thereby produce hot combustion gases comprising hydrogen sulfide, sulfur dioxide, carbon dioxide, water, and elemental sulfur; introducing the hot combustion gases into a Claus catalytic reactor; subjecting the hot combustion gases in the catalytic reactor to Claus reaction conditions in the presence of a Claus catalyst to thereby produce a Claus plant gaseous effluent stream comprising hydrogen sulfide, sulfur dioxide, carbon dioxide, water, and elemental sulfur; introducing the Claus plant gaseous effluent into a condenser to thereby produce liquid sulfur, which is recovered, and a gaseous condenser effluent, which comprises hydrogen sulfide, sulfur dioxide, carbon dioxide and water and which is divided into a recycle portion and a tailgas portion; converting substantially all sulfur species in the recycle portion of the gaseous condenser effluent to hydrogen sulfide to thereby form condenser effluent comprising hydrogen sulfide, carbon dioxide and water; removing water from the recycle portion of the condenser; and moderating the temperature in the Claus furnace by returning at least a portion of the dried recycle condenser, as a diluent stream, to a combustion zone of the Claus furnace.

  19. Sulfur recovery plant and process using oxygen

    SciTech Connect

    Palm, J.W.

    1989-01-17

    This patent describes a process for the recovery of sulfur from a gaseous stream containing hydrogen sulfide, the process comprising the steps of: (a) introducing a thermal reaction mixture comprising (1) the gaseous stream containing hydrogen sulfide, and (2) an oxygen-enriched stream of air or pure oxygen into a combustion zone of a Claus furnace; (b) combusting the thermal reaction mixture in the Claus furnace to thereby produce hot combustion gases comprising hydrogen sulfide, sulfur dioxide, carbon dioxide, water, and elemental sulfur; (c) introducing the hot combustion gases into a Claus catalytic reactor; (d) subjecting the hot combustion gases in the catalytic reactor to Claus reaction conditions in the presence of a Claus catalyst to thereby produce a Claus plant gaseous effluent stream comprising hydrogen sulfide, sulfur dioxide, carbon dioxide, water, and elemental sulfur; (e) introducing the Claus plant gaseous effluent into a condenser to thereby produce liquid sulfur, which is recovered, and a gaseous condenser effluent, which comprises hydrogen sulfide, sulfur dioxide, carbon dioxide and water; (f) converting substantially all sulfur species in the gaseous condenser effluent to hydrogen sulfide, to thereby form a condenser effluent comprising hydrogen sulfide, carbon dioxide and water; (g) removing water from the condenser effluent from step (f); and (h) moderating the temperature in the Claus furnace by returning at least a portion of the dried condenser effluent from step (g), as a diluent stream, to a combustion zone of the Claus furnace in step (a) above.

  20. Oxygen acoustic solitary waves in a magnetized plasma

    NASA Technical Reports Server (NTRS)

    Qian, S.; Lotko, W.; Hudson, M. K.

    1989-01-01

    Ion-acoustic solitary waves in a magnetized plasma containing an arbitrary mixture of H(+) and O(+) ions are studied. A nonlinear wave equation has been derived from the Poisson-Vlasov equations, including a uniform magnetic field and dissipation due to reflected electrons. When dissipation is ignored, the equation has soliton solutions associated with both oxygen and hydrogen acoustic modes, which can be either rarefactive or compressive depending on the ion concentrations and the electron/ion temperature ratio and, more weakly, on the bulk drifts of the species. If electron reflection is included, the solitary wave can be intensified. Under somewhat restrictive conditions the oxygen solitary wave is rarefactive and propagates with a velocity comparable to that observed by the Viking satellite. The three-dimensional solitons obey a relation of scales parallel to the magnetic field and in the transverse direction. Computer simulations of one-dimensional versions of the nonlinear wave equation are presented.

  1. Plasma-generated reactive oxygen species for biomedical applications

    NASA Astrophysics Data System (ADS)

    Sousa, J. S.; Hammer, M. U.; Winter, J.; Tresp, H.; Duennbier, M.; Iseni, S.; Martin, V.; Puech, V.; Weltmann, K. D.; Reuter, S.

    2012-10-01

    To get a better insight into the effects of reactive oxygen species (ROS) on cellular components, fundamental studies are essential to determine the nature and concentration of plasma-generated ROS, and the chemistry induced in biological liquids by those ROS. In this context, we have measured the absolute density of the main ROS created in three different atmospheric pressure plasma sources: two geometrically distinct RF-driven microplasma jets (μ-APPJ [1] and kinpen [2]), and an array of microcathode sustained discharges [3]. Optical diagnostics of the plasma volumes and effluent regions have been performed: UV absorption for O3 and IR emission for O2(a^1δ) [4]. High concentrations of both ROS have been obtained (10^14--10^17cm-3). The effect of different parameters, such as gas flows and mixtures and power coupled to the plasmas, has been studied. For plasma biomedicine, the determination of the reactive species present in plasma-treated liquids is of great importance. In this work, we focused on the measurement of the concentration of H2O2 and NOX radicals, generated in physiological solutions like NaCl and PBS.[4pt] [1] N. Knake et al., J. Phys. D: App. Phys. 41, 194006 (2008)[0pt] [2] K.D. Weltmann et al., Pure Appl. Chem. 82, 1223 (2010)[0pt] [3] J.S. Sousa et al., Appl. Phys. Lett. 97, 141502 (2010)[0pt] [4] J.S. Sousa et al., Appl. Phys. Lett. 93, 011502 (2008)

  2. Absorption process for producing oxygen and nitrogen and solution therefor

    DOEpatents

    Roman, I.C.; Baker, R.W.

    1990-09-25

    Process for the separation and purification of oxygen and nitrogen is disclosed which utilizes solutions of oxygen carriers to selectively absorb oxygen from a gaseous stream, leaving nitrogen as a byproduct. In the process, an oxygen carrier capable of reversibly binding molecular oxygen is dissolved in a solvent solution, which absorbs oxygen from an oxygen-containing gaseous feed stream such as atmospheric air and desorbs oxygen to a gaseous product stream. The feed stream is maintained at a sufficiently high oxygen pressure to keep the oxygen carrier in its oxygenated form during absorption, while the product stream is maintained at a sufficiently low oxygen pressure to keep the carrier in its deoxygenated form during desorption. In an alternate mode of operation, the carrier solution is maintained at a sufficiently low temperature and high oxygen pressure to keep the oxygen carrier in its oxygenated form during absorption, and at a sufficiently high temperature to keep the carrier in its deoxygenated form during desorption. Under such conditions, exceptionally high oxygen concentrations on the order of 95% to 99% are obtained, as well as a long carrier lifetime in excess of 3 months, making the process commercially feasible. 1 figure

  3. Absorption process for producing oxygen and nitrogen and solution therefor

    DOEpatents

    Roman, Ian C.

    1984-01-01

    Process for the separation and purification of oxygen and nitrogen is disclosed which utilizes solutions of oxygen carriers to selectively absorb oxygen from a gaseous stream, leaving nitrogen as a byproduct. In the process, an oxygen carrier capable of reversibly binding molecular oxygen is dissolved in a solvent solution, which absorbs oxygen from an oxygen-containing gaseous feed stream such as atmospheric air and desorbs oxygen to a gaseous product stream. The feed stream is maintained at a sufficiently high oxygen pressure to keep the oxygen carrier in its oxygenated form during absorption, while the product stream is maintained at a sufficiently low oxygen pressure to keep the carrier in its deoxygenated form during desorption. In an alternate mode of operation, the carrier solution is maintained at a sufficiently low temperature and high oxygen pressure to keep the oxygen carrier in its oxygenated form during absorption, and at a sufficiently high temperature to keep the carrier in its deoxygenated form during desorption. Under such conditions, exceptionally high oxygen concentrations on the order of 95% to 99% are obtained, as well as a long carrier lifetime in excess of 3 months, making the process commercially feasible.

  4. Absorption process for producing oxygen and nitrogen and solution therefor

    DOEpatents

    Roman, Ian C.; Baker, Richard W.

    1990-09-25

    Process for the separation and purification of oxygen and nitrogen is disclosed which utilizes solutions of oxygen carriers to selectively absorb oxygen from a gaseous stream, leaving nitrogen as a byproduct. In the process, an oxygen carrier capable of reversibly binding molecular oxygen is dissolved in a solvent solution, which absorbs oxygen from an oxygen-containing gaseous feed stream such as atmospheric air and desorbs oxygen to a gaseous product stream. The feed stream is maintained at a sufficiently high oxygen pressure to keep the oxygen carrier in its oxygenated form during absorption, while the product stream is maintained at a sufficiently low oxygen pressure to keep the carrier in its deoxygenated form during desorption. In an alternate mode of operation, the carrier solution is maintained at a sufficiently low temperature and high oxygen pressure to keep the oxygen carrier in its oxygenated form during absorption, and at a sufficiently high temperature to keep the carrier in its deoxygenated form during desorption. Under such conditions, exceptionally high oxygen concentrations on the order of 95% to 99% are obtained, as well as a long carrier lifetime in excess of 3 months, making the process commercially feasible.

  5. Contamination and uniformity control in plasma processing tools

    SciTech Connect

    Selwyn, G.; Brackbill, J.; Jones, M.; Winske, D.

    1996-10-01

    This is the final report of a one-year, Laboratory-Directed Research and Development (LDRD) project at the Los Alamos National Laboratory (LANL). We have collaborated with industry to build a laboratory to study plasma processing, a surface-cleaning technique that uses short-lived, gaseous reactants in place of chemical solvents. We have performed experiments and developed computer models to understand how complex substrate geometries affect plasma electrical properties and to demonstrate the feasibility of generating metastable molecular oxygen in a plasma.

  6. Identification of deep trap energies and influences of oxygen plasma ashing on semiconductor carrier lifetime

    NASA Astrophysics Data System (ADS)

    Koprowski, A.; Humbel, O.; Plappert, M.; Krenn, H.

    2015-03-01

    We have performed an analytical study of the effects of oxygen plasma ashing processes in semiconductor device fabrication and its impact on minority carrier lifetime in high voltage semiconductor devices. Our work includes a critical background study of life time killing mechanisms by deep traps imparted into the semiconductor by barrel plasma ashing. The Elymat technique provides the opportunity to measure lifetime and diffusion length of minority carriers and surface photo voltage (SPV) measurement was used to analyse influences of process parameters such as photoresist, time budget and positioning in the process chamber. It was shown that in microwave plasma processes the diffusion length changes severely with tempering at 200 °C, whereas RF-plasma processes show a significant process time-dependence. Batch tools in general suffer from a strong first wafer effect which could be correlated with the static electrical parameters of the semiconductor devices. The trap identities were detected by using deep level transient spectroscopy and the chemical species of the traps has been proven by inductive coupled plasma mass spectrometry. The deep-bandgap trap energies are reliable fingerprints of the chosen process parameters such as process time and of resist-influences. By microwave plasma processes intrinsic Fe and FeB-complex levels were identified and a good agreement with the SPV-measurement and electrical device characteristic was shown. RF-plasma processes impart levels attributed to Pt levels and an additional level, which could be identified as a trap level probably forming a complex of Pt and H.

  7. Ionized gas (plasma) delivery of reactive oxygen species (ROS) into artificial cells

    NASA Astrophysics Data System (ADS)

    Hong, Sung-Ha; Szili, Endre J.; Jenkins, A. Toby A.; Short, Robert D.

    2014-09-01

    This study was designed to enhance our understanding of how reactive oxygen species (ROS), generated ex situ by ionized gas (plasma), can affect the regulation of signalling processes within cells. A model system, comprising of a suspension of phospholipid vesicles (cell mimics) encapsulating a ROS reporter, was developed to study the plasma delivery of ROS into cells. For the first time it was shown that plasma unequivocally delivers ROS into cells over a sustained period and without compromising cell membrane integrity. An important consideration in cell and biological assays is the presence of serum, which significantly reduced the transfer efficiency of ROS into the vesicles. These results are key to understanding how plasma treatments can be tailored for specific medical or biotechnology applications. Further, the phospholipid vesicle ROS reporter system may find use in other studies involving the application of free radicals in biology and medicine.

  8. Plasma immersion ion implantation for silicon processing

    NASA Astrophysics Data System (ADS)

    Yankov, Rossen A.; Mändl, Stephan

    2001-04-01

    Plasma Immersion Ion Implantation (PIII) is a technology which is currently widely investigated as an alternative to conventional beam line implantation for ultrashallow doping beyond the 0.15 m technology. However, there are several other application areas in modern semiconductor processing. In this paper a detailed discussion of the PIII process for semiconductors and of actual as well as future applications is given. Besides the well known advantages of PIII - fast process, implantation of the whole surface, low cost of ownership - several peculiarities - like spread of the implantation energy due to finite rise time or collisions, no mass separation, high secondary electron emission - must be mentioned. However, they can be overcome by adjusting the system and the process parameters. Considering the applications, ultrashallow junction formation by PIII is an established industrial process, whereas SIMOX and Smart-Cut by oxygen and hydrogen implantation are current topics between research and introduction into industry. Further applications of PIII, of which some already are research topics and some are only investigated by conventional ion implantation, include seeding for metal deposition, gettering of metal impurities, etch stop layers and helium implantation for localized lifetime control.

  9. Nanoparticulate-catalyzed oxygen transfer processes

    DOEpatents

    Hunt, Andrew T.; Breitkopf, Richard C.

    2009-12-01

    Nanoparticulates of oxygen transfer materials that are oxides of rare earth metals, combinations of rare earth metals, and combinations of transition metals and rare earth metals are used as catalysts in a variety of processes. Unexpectedly large thermal efficiencies are achieved relative to micron sized particulates. Processes that use these catalysts are exemplified in a multistage reactor. The exemplified reactor cracks C6 to C20 hydrocarbons, desulfurizes the hydrocarbon stream and reforms the hydrocarbons in the stream to produce hydrogen. In a first reactor stage the steam and hydrocarbon are passed through particulate mixed rare earth metal oxide to crack larger hydrocarbon molecules. In a second stage, the steam and hydrocarbon are passed through particulate material that desulfurizes the hydrocarbon. In a third stage, the hydrocarbon and steam are passed through a heated, mixed transition metal/rare earth metal oxide to reform the lower hydrocarbons and thereby produce hydrogen. Stages can be alone or combined. Parallel reactors can provide continuous reactant flow. Each of the processes can be carried out individually.

  10. Non-thermal dielectric barrier discharge plasma induces angiogenesis through reactive oxygen species

    PubMed Central

    Arjunan, Krishna Priya; Friedman, Gary; Fridman, Alexander; Clyne, Alisa Morss

    2012-01-01

    Vascularization plays a key role in processes such as wound healing and tissue engineering. Non-thermal plasma, which primarily produces reactive oxygen species (ROS), has recently emerged as an efficient tool in medical applications including blood coagulation, sterilization and malignant cell apoptosis. Liquids and porcine aortic endothelial cells were treated with a non-thermal dielectric barrier discharge plasma in vitro. Plasma treatment of phosphate-buffered saline (PBS) and serum-free medium increased ROS concentration in a dose-dependent manner, with a higher concentration observed in serum-free medium compared with PBS. Species concentration inside cells peaked 1 h after treatment, followed by a decrease 3 h post treatment. Endothelial cells treated with a plasma dose of 4.2 J cm–2 had 1.7 times more cells than untreated samples 5 days after plasma treatment. The 4.2 J cm–2 plasma dose increased two-dimensional migration distance by 40 per cent compared with untreated control, while the number of cells that migrated through a three-dimensional collagen gel increased by 15 per cent. Tube formation was also enhanced by plasma treatment, with tube lengths in plasma-treated samples measuring 2.6 times longer than control samples. A fibroblast growth factor-2 (FGF-2) neutralizing antibody and ROS scavengers abrogated these angiogenic effects. These data indicate that plasma enhanced proliferation, migration and tube formation is due to FGF-2 release induced by plasma-produced ROS. Non-thermal plasma may be used as a potential tool for applying ROS in precise doses to enhance vascularization. PMID:21653568

  11. Optical emission spectroscopy characterization of oxygen plasma during degradation of Escherichia coli

    SciTech Connect

    Vujosevic, D.; Mozetic, M.; Cvelbar, U.; Krstulovic, N.; Milosevic, S.

    2007-05-15

    Optical emission spectroscopy was applied for plasma characterization during sterilization of substrates contaminated with bacteria. The amount of 10{sup 10}/ml cells of Escherichia coli was carefully applied to glass substrates and exposed to oxygen plasma glow discharge at different pressures between 30 and 200 Pa. Plasma was created in a glass discharge tube by an inductively coupled rf generator at the frequency of 27.12 MHz and output power of about 250 W. The electron temperature and plasma density were estimated with a double Langmuir probe. They were between 3 and 5 eV and 2 and 35x10{sup 15} m{sup -3}. Density of neutral oxygen atoms was measured with a catalytic probe, and was between 2 and 6x10{sup 21} m{sup -3}. Optical emission spectroscopy was performed with a low resolution spectrometer. The emission from carbon monoxide and nitrogen molecules was used to monitor the evolution of bacteria degradation. Both signals expressed a well defined maximum corresponding to peak erosion of bacteria by plasma radicals. As the sterilization was accomplished, both CO and N{sub 2} lines fell below the detection limit of the spectrometer. The bacteria degradation was also monitored by scanning electron microscope (SEM) and culturing. The SEM images corresponded well with the evolution of CO and N{sub 2} lines so the optical emission spectroscopy found a reliable tool for monitoring the sterilization process.

  12. Optical emission spectroscopy characterization of oxygen plasma during degradation of Escherichia coli

    NASA Astrophysics Data System (ADS)

    Vujošević, D.; Mozetič, M.; Cvelbar, U.; Krstulović, N.; Milošević, S.

    2007-05-01

    Optical emission spectroscopy was applied for plasma characterization during sterilization of substrates contaminated with bacteria. The amount of 1010/ml cells of Escherichia coli was carefully applied to glass substrates and exposed to oxygen plasma glow discharge at different pressures between 30 and 200Pa. Plasma was created in a glass discharge tube by an inductively coupled rf generator at the frequency of 27.12MHz and output power of about 250W. The electron temperature and plasma density were estimated with a double Langmuir probe. They were between 3 and 5eV and 2 and 35×1015m-3. Density of neutral oxygen atoms was measured with a catalytic probe, and was between 2 and 6×1021m-3. Optical emission spectroscopy was performed with a low resolution spectrometer. The emission from carbon monoxide and nitrogen molecules was used to monitor the evolution of bacteria degradation. Both signals expressed a well defined maximum corresponding to peak erosion of bacteria by plasma radicals. As the sterilization was accomplished, both CO and N2 lines fell below the detection limit of the spectrometer. The bacteria degradation was also monitored by scanning electron microscope (SEM) and culturing. The SEM images corresponded well with the evolution of CO and N2 lines so the optical emission spectroscopy found a reliable tool for monitoring the sterilization process.

  13. Morphological evolution of self-deposition Bi2Se3 nanosheets by oxygen plasma treatment

    PubMed Central

    Jia, Guozhi; Wu, Zengna; Wang, Peng; Yao, Jianghong; Chang, Kai

    2016-01-01

    Bi2Se3 nanosheets were successfully synthesized by a microwave-assisted approach in the presence of polyvinylpyrroli done at a temperature of 180 °C for 2 h. The thin film was prepared on a silicon wafer via a self-deposition process in a Bi2Se3 nanosheet ink solution using the evaporation-induced self-assembly method. The structure and morphology of the obtained products were characterized by X-ray diffraction, scanning electron microscopy (SEM), x-ray photoelectron spectroscopy, and Raman spectroscopy. The highly uniform Bi2Se3 particles could be formed by controlling the oxygen plasma treatment time. After the plasma pretreatment from 10 to 20 s, the surface of Bi2Se3 film evolved from the worm-like structure to particles. The highly uniform thin film was formed on further increasing the plasma treatment time, which is consistent with the observed SEM results. Several important processes can result in the morphological evolution of Bi2Se3 nanosheets: (1) formation of Bi2Se3 oxide layer; (2) self-assembly of oxide nanoparticles under the action of high-energy oxygen plasma; and (3) electrostatic interaction and etching mechanism. PMID:26923325

  14. Morphological evolution of self-deposition Bi2Se3 nanosheets by oxygen plasma treatment

    NASA Astrophysics Data System (ADS)

    Jia, Guozhi; Wu, Zengna; Wang, Peng; Yao, Jianghong; Chang, Kai

    2016-02-01

    Bi2Se3 nanosheets were successfully synthesized by a microwave-assisted approach in the presence of polyvinylpyrroli done at a temperature of 180 °C for 2 h. The thin film was prepared on a silicon wafer via a self-deposition process in a Bi2Se3 nanosheet ink solution using the evaporation-induced self-assembly method. The structure and morphology of the obtained products were characterized by X-ray diffraction, scanning electron microscopy (SEM), x-ray photoelectron spectroscopy, and Raman spectroscopy. The highly uniform Bi2Se3 particles could be formed by controlling the oxygen plasma treatment time. After the plasma pretreatment from 10 to 20 s, the surface of Bi2Se3 film evolved from the worm-like structure to particles. The highly uniform thin film was formed on further increasing the plasma treatment time, which is consistent with the observed SEM results. Several important processes can result in the morphological evolution of Bi2Se3 nanosheets: (1) formation of Bi2Se3 oxide layer; (2) self-assembly of oxide nanoparticles under the action of high-energy oxygen plasma; and (3) electrostatic interaction and etching mechanism.

  15. Morphological evolution of self-deposition Bi2Se3 nanosheets by oxygen plasma treatment.

    PubMed

    Jia, Guozhi; Wu, Zengna; Wang, Peng; Yao, Jianghong; Chang, Kai

    2016-01-01

    Bi2Se3 nanosheets were successfully synthesized by a microwave-assisted approach in the presence of polyvinylpyrroli done at a temperature of 180 °C for 2 h. The thin film was prepared on a silicon wafer via a self-deposition process in a Bi2Se3 nanosheet ink solution using the evaporation-induced self-assembly method. The structure and morphology of the obtained products were characterized by X-ray diffraction, scanning electron microscopy (SEM), x-ray photoelectron spectroscopy, and Raman spectroscopy. The highly uniform Bi2Se3 particles could be formed by controlling the oxygen plasma treatment time. After the plasma pretreatment from 10 to 20 s, the surface of Bi2Se3 film evolved from the worm-like structure to particles. The highly uniform thin film was formed on further increasing the plasma treatment time, which is consistent with the observed SEM results. Several important processes can result in the morphological evolution of Bi2Se3 nanosheets: (1) formation of Bi2Se3 oxide layer; (2) self-assembly of oxide nanoparticles under the action of high-energy oxygen plasma; and (3) electrostatic interaction and etching mechanism. PMID:26923325

  16. Research on atmospheric pressure plasma processing sewage

    NASA Astrophysics Data System (ADS)

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

    2013-08-01

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

  17. Mechanisms of polymer degradation using an oxygen plasma generator

    NASA Technical Reports Server (NTRS)

    Colony, Joe A.; Sanford, Edward L.

    1987-01-01

    An RF oxygen plasma generator was used to produce polymer degradation which appears to be similar to that which has been observed in low Earth orbit. Mechanisms of this type of degradation were studied by collecting the reaction products in a cryogenic trap and identifying the molecular species using infrared, mass spectral, and X-ray diffraction techniques. No structurally dependent species were found from Kapton, Teflon, or Saran polymers. However, very reactive free radical entities are produced during the polymer degradation, as well as carbon dioxide and water. Reactions of the free radicals with the glass reaction vessel, with copper metal in the cold trap, and with a triphenyl phosphate scavenger in the cold trap, demonstrated the reactivity of the primary products.

  18. As-grown Y-Ba-Cu-O thin films by reactive coevaporation with oxygen plasma cooling

    NASA Astrophysics Data System (ADS)

    Matsumoto, M.; Akoh, H.; Takada, S.

    1989-10-01

    We have developed a new fabrication process of as-grown Y-Ba-Cu-O thin films using a reactive coevaporation method specially with the rf-plasma cooling in the low oxygen pressure of 0.4 mTorr. By this O2 plasma cooling process, the transition temperature Tc is improved from 40 to 81 K for the film with a thickness of 1000 Å. The x-ray diffraction analysis shows that the activated oxygen species generated by the rf plasma make Y-Ba-Cu-O films oxidize sufficiently even in the low pressure of oxygen. In addition, we have studied the thickness dependence of Tc for as-grown films with various thicknesses of 60-2000 Å.

  19. As-grown Y-Ba-Cu-O thin films by reactive coevaporation with oxygen plasma cooling

    SciTech Connect

    Matsumoto, M.; Akoh, H.; Takada, S. )

    1989-10-15

    We have developed a new fabrication process of as-grown Y-Ba-Cu-O thin films using a reactive coevaporation method specially with the rf-plasma cooling in the low oxygen pressure of 0.4 mTorr. By this O{sub 2} plasma cooling process, the transition temperature {ital T}{sub {ital c}} is improved from 40 to 81 K for the film with a thickness of 1000 A. The x-ray diffraction analysis shows that the activated oxygen species generated by the rf plasma make Y-Ba-Cu-O films oxidize sufficiently even in the low pressure of oxygen. In addition, we have studied the thickness dependence of {ital T}{sub {ital c}} for as-grown films with various thicknesses of 60--2000 A.

  20. Plasma generating apparatus for large area plasma processing

    DOEpatents

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

    1991-07-16

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

  1. Plasma generating apparatus for large area plasma processing

    DOEpatents

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

    1991-01-01

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

  2. INTRODUCTION: Nonequilibrium Processes in Plasmas

    NASA Astrophysics Data System (ADS)

    Petrović, Zoran; Marić, Dragana; Malović, Gordana

    2009-07-01

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

  3. Atomic processes in edge plasmas

    NASA Astrophysics Data System (ADS)

    Schultz, David; Krstic, Predrag; Pindzola, Mitch; Griffin, Donald; Loch, Stuart; Ballance, Conner; Minami, Tatsuya; Reinhold, Carlos; Stuart, Steve

    2006-10-01

    Atomic processes play a number of key roles in both the physics of edge plasmas and in their diagnostics. We will provide a brief overview of a number of electron-impact and heavy-particle atomic collision calculations and the associated evaluated databases that are pertinent to edge modeling. Examples will include a large, well tested set of elastic and related transport cross sections as well as generalized collisional-radiative coefficients for all ion stages of Li and Be. We will also report on recent work that has re-evaluated widely assumed scaling relations for electron-impact ionization of excited states of hydrogen-like ions and how this affects the effective ionization rate coefficient used in a wide range of models. Finally, novel calculations of chemical sputtering, sticking, and reflection of D and D2 incident upon deuterated carbons surfaces (amorphous and graphite), in the energy range from about one eV to hundreds of eV, will be described. New and unique features of these simulations in comparison to the previous ones include the surface preparation, enhanced statistics enabled by ultrascale computer resources, and use of the most recent, improved hydrocarbon potentials.

  4. Argon–oxygen dc magnetron discharge plasma probed with ion acoustic waves

    SciTech Connect

    Saikia, Partha Saikia, Bipul Kumar; Goswami, Kalyan Sindhu; Phukan, Arindam

    2014-05-15

    The precise determination of the relative concentration of negative ions is very important for the optimization of magnetron sputtering processes, especially for those undertaken in a multicomponent background produced by adding electronegative gases, such as oxygen, to the discharge. The temporal behavior of an ion acoustic wave excited from a stainless steel grid inside the plasma chamber is used to determine the relative negative ion concentration in the magnetron discharge plasma. The phase velocity of the ion acoustic wave in the presence of negative ions is found to be faster than in a pure argon plasma, and the phase velocity increases with the oxygen partial pressure. Optical emission spectroscopy further confirms the increase in the oxygen negative ion density, along with a decrease in the argon positive ion density under the same discharge conditions. The relative negative ion concentration values measured by ion acoustic waves are compared with those measured by a single Langmuir probe, and a similarity in the results obtained by both techniques is observed.

  5. Atmospheric Pressure Plasma Process And Applications

    SciTech Connect

    Peter C. Kong; Myrtle

    2006-09-01

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

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

    PubMed

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

    2016-09-01

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

  7. Relativistic thermal plasmas - Pair processes and equilibria

    NASA Technical Reports Server (NTRS)

    Lightman, A. P.

    1982-01-01

    The work of Bisnovatyi-Kogan, Zel'dovich and Sunyaev (1971) is extended and generalized, through the inclusion of pair-producing photon processes and effects due to the finite size of the plasma, in an investigation of the equilibria of relativistic thermal plasmas which takes into account electron-positron creation and annihilation and photons produced within the plasma. It is shown that the bridge between an effectively thin plasma and an effectively thick plasma occurs in the transrelativistic region, where the dimensionless temperature value is between 0.1 and 1.0 and the temperature remains in this region over a great luminosity range.

  8. Effect of oxygen plasma on the properties of tantalum oxide films

    SciTech Connect

    Kalygina, V. M. Zarubin, A. N.; Novikov, V. A.; Petrova, Yu. S.; Skakunov, M. S.; Tolbanov, O. P.; Tyazhev, A. V.; Yaskevich, T. M.

    2010-09-15

    The effect of oxygen plasma on the leakage current, permittivity, and the dielectric loss tangent of Ta{sub 2}O{sub 5} thin layers (300-400 nm) is studied. It is suggested to treat tantalum oxide films in oxygen plasma to control their electrical and dielectric characteristics.

  9. Induced hydrophobic recovery of oxygen plasma-treated surfaces

    PubMed Central

    Guckenberger, David J.; Berthier, Erwin; Young, Edmond W. K.; Beebe, David J.

    2014-01-01

    Plasma treatment is a widely used method in microfabrication laboratories and the plasticware industry to functionalize surfaces for device bonding and preparation for mammalian cell culture. However, spatial control of plasma treatment is challenging because it typically requires a tedious masking step that is prone to alignment errors. Currently, there are no available methods to actively revert a surface from a treated hydrophilic state to its original hydrophobic state. Here, we describe a method that relies on physical contact treatment (PCT) to actively induce hydrophobic recovery of plasma-treated surfaces. PCT involves applying brushing and peeling processes with common wipers and tapes to reverse the wettability of hydrophilized surfaces while simultaneously preserving hydrophilicity of non-contacted surfaces. We demonstrate that PCT is a user-friendly method that allows 2D and 3D surface patterning of hydrophobic regions, and the protection of hydrophilic surfaces from unwanted PCT-induced recovery. This method will be useful in academic and industrial settings where plasma treatment is frequently used. PMID:22592853

  10. Atomic Oxygen Durability Evaluation of Protected Polymers Using Thermal Energy Plasma Systems

    NASA Technical Reports Server (NTRS)

    Banks, Bruce A.; Rutledge, Sharon K.; Degroh, Kim K.; Stidham, Curtis R.; Gebauer, Linda; Lamoreaux, Cynthia M.

    1995-01-01

    The durability evaluation of protected polymers intended for use in low Earth orbit (LEO) has necessitated the use of large-area, high-fluence, atomic oxygen exposure systems. Two thermal energy atomic oxygen exposure systems which are frequently used for such evaluations are radio frequency (RF) plasma ashers and electron cyclotron resonance plasma sources. Plasma source testing practices such as ample preparation, effective fluence prediction, atomic oxygen flux determination, erosion measurement, operational considerations, and erosion yield measurements are presented. Issues which influence the prediction of in-space durability based on ground laboratory thermal energy plasma system testing are also addressed.

  11. Chlorination processing of local planetary ores for oxygen and metallurgically important metals

    NASA Technical Reports Server (NTRS)

    Lynch, D. C.

    1989-01-01

    The use of chlorine to extract, reclaim, and purify metals has attractive possibilities for extraterrestrial processing of local planetary resources. While a complete cyclic process has been proposed for the recovery of metallurgically significant metals and oxygen, herein the chlorination step of the cycle is examined. An experimental apparatus for reacting refractory materials, such as ilmenite, in a microwave induced plasma is being built. Complex equilibria calculations reveal that stable refractory materials can, under the influence of a plasma, undergo chlorination and yield oxygen as a by-product. These issues and the potential advantages for plasma processing in space are reviewed. Also presented is a discussion of the complex equilibria program used in the analysis.

  12. Plasma-assisted microwave processing of materials

    NASA Technical Reports Server (NTRS)

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

    1998-01-01

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

  13. Theoretical investigations of plasma processes

    NASA Technical Reports Server (NTRS)

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

    1976-01-01

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

  14. Usefulness of Magnetic Neutral Loop Discharge Plasma in Plasma Processing

    NASA Astrophysics Data System (ADS)

    Tsuboi, Hideo; Itoh, Masahiro; Tanabe, Masafumi; Hayashi, Toshio; Uchida, Taijiro

    1995-05-01

    Usefulness in plasma processing is demonstrated for a plasma produced in a closed magnetic neutral loop, which consists of zero magnetic field points connected continuously. A preliminary experiment was carried out to show the advantage of magnetic neutral loop discharge (NLD) plasma in sputter etching processing of SiO2/Si wafer in the lower Ar gas pressure range. The experiment shows that a high-density plasma was obtained for Ar gas lower than 0.1 Pa and the sputter etching rate is 3 times higher than that for the usual inductively coupled plasma (ICP). In a large-loop case, the sputter etching profile obtained has a peak at a radius along the azimuthal direction. This implies that a uniform etching profile could be realized by controlling the radius of the neutral loop during process operation. The NLD plasma current induced with an rf primary one-turn antenna coil reaches up to one-third of that of the primary.

  15. Femtosecond, two-photon laser-induced-fluorescence imaging of atomic oxygen in an atmospheric-pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Schmidt, Jacob B.; Sands, Brian L.; Kulatilaka, Waruna D.; Roy, Sukesh; Scofield, James; Gord, James R.

    2015-06-01

    Femtosecond, two-photon-absorption laser-induced-fluorescence (fs-TALIF) spectroscopy is employed to measure space- and time-resolved atomic-oxygen distributions in a nanosecond, repetitively pulsed, externally grounded, atmospheric-pressure plasma jet flowing helium with a variable oxygen admixture. The high-peak-intensity, low-average-energy femtosecond pulses result in increased TALIF signal with reduced photolytic inferences. This allows 2D imaging of absolute atomic-oxygen number densities ranging from 5.8   ×   1015 to 2.0   ×   1012cm-3 using a cooled CCD with an external intensifier. Xenon is used for signal and imaging-system calibrations to quantify the atomic-oxygen fluorescence signal. Initial results highlight a transition in discharge morphology from annular to filamentary, corresponding with a change in plasma chemistry from ozone to atomic oxygen production, as the concentration of oxygen in the feed gas is changed at a fixed voltage-pulse-repetition rate. In this configuration, significant concentrations of reactive oxygen species may be remotely generated by sustaining an active discharge beyond the confines of the dielectric capillary, which may benefit applications that require large concentrations of reactive oxygen species such as material processing or biomedical devices.

  16. Surface studies of plasma processed Nb samples

    SciTech Connect

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

    2015-01-01

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

  17. Space plasma physics: I - Stationary processes

    NASA Technical Reports Server (NTRS)

    Hasegawa, Akira; Sato, Tetsuya

    1989-01-01

    The physics of stationary processes in space plasmas is examined theoretically in an introduction intended for graduate students. The approach involves the extensive use of numerical simulations. Chapters are devoted to fundamental principles, small-amplitude waves, and the stationary solar plasma system; typical measurement data and simulation results are presented graphically.

  18. Surface energy increase of oxygen-plasma-treated PET

    SciTech Connect

    Cioffi, M.O.H.; Voorwald, H.J.C.; Mota, R.P

    2003-03-15

    Prosthetic composite is a widely used biomaterial that satisfies the criteria for application as an organic implant without adverse reactions. Polyethylene therephthalate (PET) fiber-reinforced composites have been used because of the excellent cell adhesion, biodegradability and biocompatibility. The chemical inertness and low surface energy of PET in general are associated with inadequate bonds for polymer reinforcements. It is recognized that the high strength of composites, which results from the interaction between the constituents, is directly related to the interfacial condition or to the interphase. A radio frequency plasma reactor using oxygen was used to treat PET fibers for 5, 20, 30 and 100 s. The treatment conditions were 13.56 MHz, 50 W, 40 Pa and 3.33x10{sup -7} m{sup 3}/s. A Rame-Hart goniometer was used to measure the contact angle and surface energy variation of fibers treated for different times. The experimental results showed contact angle values from 47 deg. to 13 deg. and surface energies from 6.4x10{sup -6} to 8.3x10{sup -6} J for the range of 5 to 100 s, respectively. These results were confirmed by the average ultimate tensile strength of the PET fiber/ polymethylmethacrylate (PMMA) matrix composite tested in tensile mode and by scanning electron microscopy.

  19. Importance of atomic oxygen in preheating zone in plasma-assisted combustion of a steady-state premixed burner flame

    NASA Astrophysics Data System (ADS)

    Zaima, K.; Akashi, H.; Sasaki, K.

    2015-09-01

    It is widely believed that electron impact processes play essential roles in plasma-assisted combustion. However, the concrete roles of high-energy electrons have not been fully understood yet. In this work, we examined the density of atomic oxygen in a premixed burner flame with the superposition of dielectric barrier discharge (DBD). The density of atomic oxygen in the reaction zone was not affected by the superposition of DBD, indicating that the amount of atomic oxygen produced by combustion reactions was much larger than that produced by electron impact processes. On the other hand, in the preheating zone, we observed high-frequency oscillation of the density of atomic oxygen at the timings of the pulsed current of DBD. The oscillation suggests the rapid consumption of additional atomic oxygen by combustion reactions. A numerical simulation using Chemkin indicates the shortened ignition delay time when adding additional atomic oxygen in the period of low-temperature oxidation. The present results reveals the importance of atomic oxygen, which is produced by the effect of high-energy electrons, in the preheating zone in plasma-assisted combustion of the steady-state premixed burner flame.

  20. Efficiency evaluation of oxygen enrichment in energy conversion processes

    SciTech Connect

    Bomelburg, H.J.

    1983-12-01

    The extent to which energy conversion efficiencies can be increased by using oxygen or oxygen-enriched air for combustion was studied. Combustion of most fuels with oxygen instead of air was found to have five advantages: increases combustion temperature and efficiency, improves heat transfer at high temperatures, reduces nitrous oxide emissions, permits a high ration of exhaust gas recirculation and allows combustion of certain materials not combustible in air. The same advantages, although to a lesser degree, are apparent with oxygen-enriched air. The cost-effectiveness of the process must necessarily be improved by about 10% when using oxygen instead of air before such use could become justifiable on purely economic terms. Although such a modest increase appears to be attainable in real situations, this study ascertained that it is not possible to generally assess the economic gains. Rather, each case requires its own evaluation. For certain processes industry has already proven that the use of oxygen leads to more efficient plant operation. Several ideas for essentially new applications are described. Specifically, when oxygen is used with exhaust gas recirculation in external or internal combustion engines. It appears also that the advantages of pulse combustion can be amplified further if oxygen is used. When burning wet fuels with oxygen, direct steam generation becomes possible. Oxygen combustion could also improve processes for in situ gasification of coals, oil shales, peats, and other wet fuels. Enhanced oil recovery by fire flooding methods might also become more effective if oxygen is used. The cold energy contained in liquid oxygen can be substantially recovered in the low end of certain thermodynamic cycles. Further efforts to develop certain schemes for using oxygen for combustion appear to be justified from both the technical and economic viewpoints.

  1. Transport processes in magnetically confined plasmas

    SciTech Connect

    Callen, J.D.

    1991-12-01

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

  2. Transport processes in magnetically confined plasmas

    SciTech Connect

    Callen, J.D.

    1991-12-01

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

  3. Plasma acceleration processes in an ablative pulsed plasma thruster

    SciTech Connect

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

    2007-03-15

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

  4. Plasma-Induced Oxygen Vacancies in Ultrathin Hematite Nanoflakes Promoting Photoelectrochemical Water Oxidation.

    PubMed

    Zhu, Changqing; Li, Changli; Zheng, Maojun; Delaunay, Jean-Jacques

    2015-10-14

    The incorporation of oxygen vacancies in hematite has been investigated as a promising route to improve oxygen evolution reaction activity of hematite photoanodes used in photoelectrochemical water oxidation. However, introducing oxygen vacancies intentionally in α-Fe2O3 for active solar water splitting through facile and effective methods remains a challenge. Herein, air plasma treatment is shown to produce oxygen vacancies in α-Fe2O3, and ultrathin α-Fe2O3 nanoflakes are used to investigate the effect of oxygen vacancies on the performance of photoelectrochemical oxygen oxidation. Increasing the plasma treatment duration and power is found to increase the density of oxygen vacancies and leads to a significant enhancement of the photocurrent response. The nanoflake photoanode with the optimized plasma treatment yields an incident photo-to-current conversion efficiency of 35.4% at 350 nm under 1.6 V vs RHE without resorting to any other cocatalysts, an efficiency far exceeding that of the pristine α-Fe2O3 nanoflakes (∼2.2%). Evidence for the presence of high density of oxygen vacancies confined in nanoflakes is clarified by X-ray photoelectron spectroscopy. The increased number of oxygen vacancies after plasma treatment resulting in an increased carrier density is interpreted as the main cause for the enhanced oxygen evolution reaction activity. PMID:26400020

  5. Treatment Characteristics of Second Order Structure of Proteins Using Low-Pressure Oxygen RF Plasma

    NASA Astrophysics Data System (ADS)

    Hayashi, Nobuya; Nakahigashi, Akari; Kawaguchi, Ryutaro; Goto, Masaaki

    2010-10-01

    Removal of proteins from the surface of medical equipments is attempted using oxygen plasma produced by RF discharge. FTIR spectra indicate that the bonding of C-H and N-H in the casein protein is reduced after irradiation of oxygen plasma. Also, the second order structure of a protein such as α-helix and β-sheet are modified by the oxygen plasma. Complete removal of casein protein with the concentration of 0.016 mg/cm2 that is equivalent to remnants on the medical equipment requires two hours avoiding the damage to medical equipments.

  6. Treatment Characteristics of Second Order Structure of Proteins Using Low-Pressure Oxygen RF Plasma

    SciTech Connect

    Hayashi, Nobuya; Nakahigashi, Akari; Kawaguchi, Ryutaro; Goto, Masaaki

    2010-10-13

    Removal of proteins from the surface of medical equipments is attempted using oxygen plasma produced by RF discharge. FTIR spectra indicate that the bonding of C-H and N-H in the casein protein is reduced after irradiation of oxygen plasma. Also, the second order structure of a protein such as {alpha}-helix and {beta}-sheet are modified by the oxygen plasma. Complete removal of casein protein with the concentration of 0.016 mg/cm{sup 2} that is equivalent to remnants on the medical equipment requires two hours avoiding the damage to medical equipments.

  7. Low-temperature oxygen-plasma effects on surveyor plasmo-clay coating

    NASA Technical Reports Server (NTRS)

    Gillette, R. B.

    1972-01-01

    The objective was to determine whether the reflectance of the degraded plasmo-clay thermal control coating could be restored by exposing it to an oxygen plasma. An experiment was conducted to determine whether bulk radiation damage would be removed by a reabsorption of oxygen ions into the pigment crystal lattice. Results show that the oxygen plasma treatment can eliminate some of the lunar environment-induced degradation on the plasmo-clay coating. Visual observations of the lunar soil on the surface after plasma treatment indicated that it was still highly absorbent to light. Therefore, part of the residual discoloration could be due to lunar soil.

  8. Auroral plasma acceleration processes at Mars

    NASA Astrophysics Data System (ADS)

    Lundin, R.; Barabash, S.; Winningham, D.

    2012-09-01

    Following the first Mars Express (MEX) findings of auroral plasma acceleration above Martian magnetic anomalies[1, 2], a more detailed analysis is carried out regarding the physical processes that leads to plasma acceleration, and how they connect to the dynamo-, and energy source regions. The ultimate energy source for Martian plasma acceleration is the solar wind. The question is, by what mechanisms is solar wind energy and momentum transferred into the magnetic flux tubes that connect to Martian magnetic anomalies? What are the key plasma acceleration processes that lead to aurora and the associated ionospheric plasma outflow from Mars? The experimental setup on MEX limits our capability to carry out "auroral physics" at Mars. However, with knowledge acquired from the Earth, we may draw some analogies with terrestrial auroral physics. Using the limited data set available, consisting of primarily ASPERA and MARSIS data, an interesting picture of aurora at Mars emerges. There are some strong similarities between accelerated/heated electrons and ions in the nightside high altitude region above Mars and the electron/ion acceleration above Terrestrial discrete aurora. Nearly monoenergetic downgoing electrons are observed in conjunction with nearly monoenergetic upgoing ions. Monoenergetic counterstreaming ions and electrons is the signature of plasma acceleration in quasi-static electric fields. However, compared to the Earth's aurora, with auroral process guided by a dipole field, aurora at Mars is expected to form complex patterns in the multipole environment governed by the Martian crustal magnetic field regions. Moreover, temporal/spatial scales are different at Mars. It is therefore of interest to mention another common characteristics that exist for Earth and Mars, plasma acceleration by waves. Low-frequency, Alfvén, waves is a very powerful means of plasma acceleration in the Earth's magnetosphere. Low-frequency waves associated with plasma acceleration

  9. Low-Temperature Sterilization with Surface-Wave-Excited Oxygen Plasma

    NASA Astrophysics Data System (ADS)

    Nagatsu, Masaaki; Terashita, Fumie; Koide, Yukio

    2003-07-01

    Low-temperature plasma sterilization has been experimentally demonstrated using surface-wave plasma excited by a 2.45 GHz microwave. With the spores of Bacillus stearothermophilus and Bacillus subtilis as biological indicators, we have carried out the plasma sterilization experiments by varying the irradiation period of oxygen plasma discharges. It was experimentally confirmed that the spores with a population of 1.5 × 106 were sterilized by irradiating them with oxygen plasma discharges generated with a microwave power of 700 W at a pressure of 60-80 mTorr for 3 min or longer. From the scanning electron microscopy (SEM) analysis of the spores, we found that the sterilized spores clearly had different sizes and shapes compared with those before the plasma irradiation. Furthermore, present experiments suggested that the changes of spore shapes were mainly attributed to the reactive interactions with oxygen radicals.

  10. The influence of surface properties on the plasma dynamics in radio-frequency driven oxygen plasmas: Measurements and simulations

    SciTech Connect

    Greb, Arthur; Niemi, Kari; O'Connell, Deborah; Gans, Timo

    2013-12-09

    Plasma parameters and dynamics in capacitively coupled oxygen plasmas are investigated for different surface conditions. Metastable species concentration, electronegativity, spatial distribution of particle densities as well as the ionization dynamics are significantly influenced by the surface loss probability of metastable singlet delta oxygen (SDO). Simulated surface conditions are compared to experiments in the plasma-surface interface region using phase resolved optical emission spectroscopy. It is demonstrated how in-situ measurements of excitation features can be used to determine SDO surface loss probabilities for different surface materials.

  11. Increased Oxygen Recovery from Sabatier Systems Using Plasma Pyrolysis Technology and Metal Hydride Separation

    NASA Technical Reports Server (NTRS)

    Greenwood, Zachary W.; Abney, Morgan B.; Perry, Jay L.; Miller, Lee A.; Dahl, Roger W.; Hadley, Neal M.; Wambolt, Spencer R.; Wheeler, Richard R.

    2015-01-01

    State-of-the-art life support carbon dioxide (CO2) reduction technology is based on the Sabatier reaction where less than 50% of the oxygen required for the crew is recovered from metabolic CO2. The reaction produces water as the primary product and methane as a byproduct. Oxygen recovery is constrained by the limited availability of reactant hydrogen. This is further exacerbated when Sabatier methane (CH4) is vented as a waste product resulting in a continuous loss of reactant hydrogen. Post-processing methane with the Plasma Pyrolysis Assembly (PPA) to recover hydrogen has the potential to dramatically increase oxygen recovery and thus drastically reduce the logistical challenges associated with oxygen resupply. The PPA decomposes methane into predominantly hydrogen and acetylene. Due to the highly unstable nature of acetylene, a separation system is necessary to purify hydrogen before it is recycled back to the Sabatier reactor. Testing and evaluation of a full-scale Third Generation PPA is reported and investigations into metal hydride hydrogen separation technology is discussed.

  12. Fundamental Processes in Plasmas. Final report

    SciTech Connect

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

    2009-11-30

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

  13. Saturn Plasma Sources and Associated Transport Processes

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  14. Laser Diagnostics for Plasma Processes

    NASA Astrophysics Data System (ADS)

    Filimonov, Serguei Victor

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

  15. Surface functionalization of organic materials by weakly ionized highly dissociated oxygen plasma

    NASA Astrophysics Data System (ADS)

    Vesel, A.; Mozetic, M.

    2009-04-01

    A review on surface modification of different polymers by treatment in oxygen plasma is presented. Plasma is created in a high frequency inductively coupled gaseous discharge at the power of about 200 W. In such discharge created in pure oxygen, plasma with the following parameters is obtained: the electron temperature of about 50.000 K, the charged particle density around 1x1016 m-3, and the neutral oxygen atom density of the order of 1021 m-3. A huge flux of neutral oxygen atoms on the surface of samples exposed to plasma assures for rapid interaction with polymer materials. The modification of surface properties of the following polymers was studied: polyethyleneterephthalate (PET), polyethersulphone (PES), polyphenylenesulfide (PPS), Nylon 6 polyamide (PA6), polytetrafluoroethylene (PTFE), polystyrene (PS), polypropylene (PP) and cellulose (ink-jet paper and textile). The polymer samples were treated for 3 s in oxygen plasma at a pressure of 75 Pa where the O-atom density was the largest at 4x1021 m-3. The appearance of the functional groups on the surface of the samples was monitored by high resolution X-ray photoelectron spectroscopy (XPS). The results show that oxygen plasma treatment is an effective tool for surface modification. On all polymer surfaces increased concentration of oxygen is detected. The high resolution C1s peaks indicate formation of several new oxygen-containing functional groups. On all polymers groups like C-O, C=O and O=C-O are observed. The concentration of these groups depends on the type of polymer. The highest uptake of oxygen by the polymer was found for cellulose and the lowest for polypropylene. The only exception was polymer PTFE where practically no chemical changes were observed after plasma treatment.

  16. Electrodynamics and plasma processes in the ionosphere

    NASA Technical Reports Server (NTRS)

    Heelis, R. A.

    1987-01-01

    The paper examines the advances achieved between 1983 and 1986 on understanding ionospheric electrodynamics and associated plasma processes, including an assessment of the roles of the E- and F-region neutral winds in providing the large-scale electric field in the ionosphere, as well as of the influence of electric fields of magnetospheric origin on the motion and distribution of plasma. Studies of the factors affecting the creation and evolution of plasma structure with many different scale sizes are discussed. Consideration is also given to the ground-based and in situ techniques used in these studies.

  17. Plasma processing of superconducting radio frequency cavities

    NASA Astrophysics Data System (ADS)

    Upadhyay, Janardan

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

  18. Cooling and recombination processes in cometary plasma

    NASA Technical Reports Server (NTRS)

    Wallis, M. K.; Ong, R. S. B.

    1976-01-01

    The ion electron plasma in comets is examined for cooling processes which result from its interactions with the neutral coma. A cometary coma model is formulated that is composed predominantly of H2O and its decomposition products where electrons are cooled in a variety of processes at rates varying with energy. It is shown that solar plasma plus accumulated cometary ions and electrons is affected very strongly as it flows into the coma. The electrons are rapidly cooled and all but some 10% of the ions undergo charge exchange. Photodissociation of H2O is assumed where ion electron recombination is the dominant loss process.

  19. A spectral study of a radio-frequency plasma-generated flux of atomic oxygen

    NASA Technical Reports Server (NTRS)

    Batten, Carmen E.; Brown, Kenneth G.; Lewis, Beverley W.

    1994-01-01

    The active environment of a radio-frequency (RF) plasma generator, with and without low-pressure oxygen, has been characterized through the identification of emission lines in the spectral region from 250 to 900 nm. The environment is shown to be dependent on the partial pressure of oxygen and the power applied to the RF generator. Atomic oxygen has been found in significant amounts as well as atomic hydrogen and the molecular oxygen species O2((sup 1)Sigma). The only charged species observed was the singly charged molecular ion O2(+). With a polymer specimen in the plasma chamber, carbon monoxide was also observed. The significance of these observations with respect to previous studies using this type of generator to stimulate material degradation in space is discussed. The possibility of using these generators as atomic oxygen sources in the development of oxygen atom fluorescence sensors is explored.

  20. Optimization and Control of Plasma Doping Processes

    SciTech Connect

    Raj, Deven M.; Godet, Ludovic; Chamberlain, Nicholas; Hadidi, Kamal; Singh, Vikram; Papasouliotis, George D.

    2011-01-07

    Plasma doping (PLAD) is a well characterized alternative to beam-line technology, which has already been adopted in high volume manufacturing in the ultra high dose, low energy regime for advanced DRAM technology nodes. As semiconductor technology evolves, the demand for ever lower energy, higher dose implants will continue to grow, and the requirements for process control will become increasingly stringent. During plasma immersion ion implantation, ionized species present in the plasma are extracted and implanted into the wafer, while other processes, such as deposition, etching and sputtering, are competing in parallel. The dopant profile into the substrate results from contributions of all these mechanisms. Using the hardware and plasma composition control features present in the PLAD system to balance the contributions of the above processes, the dopant profile can be modified and dopant retention can be optimized. In this paper, we detail the process control approach used to optimize process performance for low energy, high dose implants, and validate it with plasma and wafer state data.

  1. Dopamine, Neurochemical Processes, and Oxygen Toxicity at Pressure.

    PubMed

    Rostain, Jean-Claude; Lavoute, Cécile

    2016-01-01

    All mammals, including man, exposed to breathing gas mixtures at high pressures exhibit central nervous system disturbances, which differ according to the gas used. With the use of compressed air, the increased oxygen partial pressure induces hyperoxic disturbances that consist of epileptic seizures that occur, on average, after 30 min exposure to 2.8 ATA in man or to 5 ATA in rats. Increased oxygen partial pressure induces reactive oxygen species and reactive nitrogen species production that could be related to neurotransmitter changes reported for the preepileptic phase or at pressures that produce epileptic seizures. In rats, oxygen pressures lower than 5 ATA induce a decrease of dopamine release in the stratum that could be due to disturbances of neurotransmitter regulatory processes that are different from those implicated for hyperbaric oxygen-induced epileptic seizures. © 2016 American Physiological Society. Compr Physiol 6:1339-1344, 2016. PMID:27347895

  2. A parametric study of the destruction efficiency of Bacillus spores in low pressure oxygen-based plasmas.

    PubMed

    Hury, S; Vidal, D R; Desor, F; Pelletier, J; Lagarde, T

    1998-06-01

    The destruction of Bacillus spores in oxygen-based plasmas sustained in the millitorr pressure range has been studied as functions of various biological and plasma parameters, namely Bacillus species, surface concentration of spores, treatment temperature, and gas composition. In an oxygen plasma, Bacillus stearothermophilus appears less plasma-resistant than the other spores tested. Oxygen, H2O2 and chiefly CO2 plasmas are clearly shown to be much more efficient in destroying Bacillus subtilis spores than pure argon plasma. The bacterial surface concentration on the spore carriers and the treatment temperature also lead to significant variations in the destruction efficiency of spores when using CO2 plasma. PMID:9717311

  3. Reactive Ion Etching of Polymers in Oxygen Based Plasmas: a Study of Etch Mechanisms.

    NASA Astrophysics Data System (ADS)

    Graham, Sandra Wolterman

    The reactive ion etching of polymers has been studied in oxygen-based plasmas in an effort to understand the contributions of various mechanisms to the etching of these materials. Of the four active etch mechanisms; surface damage promoted etching, chemical sputtering, chemically enhanced physical sputtering, and direct reactive ion etching; the emphasis of this work has been on determining the relative contribution of direct reactive ion etching to the overall etching process. The etching of photoresist, polyimide, and amorphous carbon in O_2-CF_4 plasmas was studied in an asymmetrical reactive ion etcher at pressures ranging from 5 to 100 mtorr. Etch yield, ion flux, and oxygen atom concentration data were collected. The fit of this data to a linear model proposed by Joubert et al. (J. Appl. Phys., 65, 1989, 5096) was compared to the fit of the data to a nonlinear model proposed by the author. The linear model accounts for contribution due to three of the four etch mechanisms, but does not include contributions due to direct reactive ion etching. The nonlinear model accounts for contributions due to all four etch mechanisms. Experimental results indicate that the nonlinear model provides a better fit to the data than does the linear model. The relative contribution of direct reactive ion etching to the etching of photoresist ranges from 27% to 81% as the pressure decreases from 100 to 5 mtorr. Similar results are obtained for polyimide and amorphous carbon.

  4. Oxygen post-treatment of plastic surface coated with plasma polymerized silicon-containing monomers

    NASA Technical Reports Server (NTRS)

    Wydeven, T. J.; Hollanhan, J. R., Jr. (Inventor)

    1979-01-01

    The abrasion resistance of plastic surfaces coated with polymerized organosilanes can be significantly improved by post-treatment of the polymerized silane in an oxygen plasma. For optical purposes, the advantages of this post-treatment are developed with a transparent polycarbonate resin substrate coated with plasma polymerized vinyltrimethoxysilane.

  5. Plasma spray processing of TBC`s

    SciTech Connect

    Herman, H.; Berndt, C.C.

    1995-10-01

    Thermal spray processing has been used for a number of years to cost-effectively apply TBC`s for a wide range of heat engine applications. In particular, bond coats are applied by vacuum plasma spray or HVOF techniques and partially-stabilized zirconia top coats are applied by plasma spray methods. Thermal spray involves melting and rapid transport of the molten particles to the substrate, where high-rate solidification and coating build-up occur. It is the very nature of this melt processing that leads to the unique layered microstructure, as well as the apparent imperfections, so readily identified with thermal spray. Therefore, although the plasma spray of TBCs has been largely successful, it is clear that a major step forward in terms of reliability and performance can be gained by a fundamental understanding of the TBC microstructure with respect to the processing technology and operating environment.

  6. Oxygen production on the Lunar materials processing frontier

    NASA Technical Reports Server (NTRS)

    Altenberg, Barbara H.

    1992-01-01

    During the pre-conceptual design phase of an initial lunar oxygen processing facility, it is essential to identify and compare the available processes and evaluate them in order to ensure the success of such an endeavor. The focus of this paper is to provide an overview of materials processing to produce lunar oxygen as one part of a given scenario of a developing lunar occupation. More than twenty-five techniques to produce oxygen from lunar materials have been identified. While it is important to continue research on any feasible method, not all methods can be implemented at the initial lunar facility. Hence, it is necessary during the pre-conceptual design phase to evaluate all methods and determine the leading processes for initial focus. Researchers have developed techniques for evaluating the numerous proposed methods in order to suggest which processes would be best to go to the Moon first. As one section in this paper, the recent evaluation procedures that have been presented in the literature are compared and contrasted. In general, the production methods for lunar oxygen fall into four categories: thermochemical, reactive solvent, pyrolytic, and electrochemical. Examples from two of the four categories are described, operating characteristics are contrasted, and terrestrial analogs are presented when possible. In addition to producing oxygen for use as a propellant and for life support, valuable co-products can be derived from some of the processes. This information is also highlighted in the description of a given process.

  7. Optimization of the process of plasma ignition of coal

    SciTech Connect

    Peregudov, V.S.

    2009-04-15

    Results are given of experimental and theoretical investigations of plasma ignition of coal as a result of its thermochemical preparation in application to the processes of firing up a boiler and stabilizing the flame combustion. The experimental test bed with a commercial-scale burner is used for determining the conditions of plasma ignition of low-reactivity high-ash anthracite depending on the concentration of coal in the air mixture and velocity of the latter. The calculations produce an equation (important from the standpoint of practical applications) for determining the energy expenditure for plasma ignition of coal depending on the basic process parameters. The tests reveal the difficulties arising in firing up a boiler with direct delivery of pulverized coal from the mill to furnace. A scheme is suggested, which enables one to reduce the energy expenditure for ignition of coal and improve the reliability of the process of firing up such a boiler. Results are given of calculation of plasma thermochemical preparation of coal under conditions of lower concentration of oxygen in the air mixture.

  8. Surface modification by plasma immersion ion processing

    NASA Astrophysics Data System (ADS)

    Walter, Kevin C.; Lee, Deok H.; He, X. M.; Baker, N. P.; Nastasi, Michael; Munson, C. P.; Scarborough, W. K.; Tuszewski, M.; Wood, B. P.

    1998-09-01

    Los Alamos National Laboratory is actively researching a surface modification technique called plasma immersion ion processing (PIIP). PIIP is the latest innovation of the plasma source ion implantation (PSII) approach to surface modification. Like PSII, PIIP allows the modification of large areas and non-planar surface geometries, however PIIP is primarily a coating deposition technology rather than solely an ion implantation technology. PIIP utilizes a pulsed-bias on a target to extract ions out of plasma for ion implantation and coating deposition. Plasmas can be made by capacitive or inductive radio frequency sources or by initiating a glow discharge during each pulse of high voltage. Plasmas of hydrocarbon gases have been used to deposit adherent diamond-like carbon (DLC) coating son a variety of ferrous and non-ferrous materials. Instead of sputter depositing interlayers to improve the adhesion of DLC, PIIP uses ion implantation to create a graded interface between the metallic substrate and the DLC coating. Demonstrating the scaleability of PIIP, a 3 m2 area has been simultaneously coated with an adherent DLC coating approximately 7 micrometers thick. Plasmas of diborane and acetylene mixtures are being used to develop deposition processes for boron-carbide coatings. Through the use of organometallics and inorganic gases, other coatings are possible. The PIIP deposition conditions, composition and tribological properties of DLC and boron-carbide coatings will be highlighted.

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

    SciTech Connect

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

    2015-12-31

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

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

    DOE PAGESBeta

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

    2015-12-31

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-03-01

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

  12. Optical emission spectroscopy of oxygen plasma induced by IR CO2 pulsed laser

    NASA Astrophysics Data System (ADS)

    Camacho, J. J.; Santos, M.; Díaz, L.; Poyato, J. M. L.

    2008-11-01

    Laser-induced breakdown (LIB) spectroscopy in oxygen at room temperature and pressures ranging from 4.6 to 75 kPa was studied using a high-power transverse excitation atmospheric CO2 laser (λ = 9.621 and 10.591 µm τFWHM = 64 ns; power densities ranging from 0.87 to 6.31 GW cm-2). The spectrum of the generated plasma is dominated by emission of strong O, O+ and weak O2+ atomic lines. Excitation temperatures of 31 500 ± 1600 K and 23 000 ± 3000 K were estimated by means of O2+ and O+ ionic lines, respectively. Electron number densities of the order of (3.5-16.5) × 1016 cm-3 were deduced from the Stark broadening of several ionic O+ lines. The characteristics of the spectral emission intensities from different species have been investigated as functions of the oxygen pressure and laser irradiance. Optical breakdown threshold intensities in O2 at 10.591 µm have been determined. The physical processes leading to LIB of oxygen have been analysed.

  13. STUDENT AWARD FINALIST: Oxygen Pathways in Streamer Discharge for Transient Plasma Ignition

    NASA Astrophysics Data System (ADS)

    Pendleton, S. J.; Bowman, S.; Singleton, D.; Watrous, J.; Carter, C.; Lempert, W.; Gundersen, M. A.

    2011-10-01

    The use of streamers for the ignition of fuels, also known as transient plasma ignition (TPI), has been shown in a variety of engines to improve combustion through decreased ignition delay, increased lean burn capability and increased energy release relative to conventional spark ignition. The mechanisms behind these improvements, however, remain poorly understood. Temperature measurements by optical emission spectroscopy demonstrate that ignition by TPI is a nonthermal process, and thus is almost entirely dependent on the production and presence of electron impact-created active species in the discharge afterglow. Of particular interest are active oxygen species due to their relatively long lifetimes at high pressures and the pivotal role they play in combustion reactions. In order to elucidate the oxygen pathways, here we report the investigation of the temporal evolution of the populations of atomic oxygen and ozone by use of two-photon absorption laser induced fluorescence (TALIF) and UV absorption, respectively. Experimental results are presented and compared to kinetic modeling of the streamers. Future experiments are proposed to better understand the physics behind TPI. Supported by NSF, AFOSR, NumerEx-ONR, AFRL-WPAFB.

  14. Signal processing methods for MFE plasma diagnostics

    SciTech Connect

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

    1985-02-01

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

  15. Oxygen plasma ashing effects on aluminum and titanium space protective coatings

    NASA Technical Reports Server (NTRS)

    Synowicki, R.; Kubik, R. D.; Hale, J. S.; Peterkin, Jane; Nafis, S.; Woollam, John A.; Zaat, S.

    1991-01-01

    Using variable angle spectroscopic ellipsometry and atomic force microscopy (AFM), the surface roughness and oxidation of aluminum and titanium thin films have been studied as a function of substrate deposition temperature and oxygen plasma exposure. Increasing substrate deposition temperatures affect film microstructure by greatly increasing grain size. Short exposures to an oxygen plasma environment produce sharp spikes rising rapidly above the surface as seen by AFM. Ellipsometric measurements were made over a wide range of plasma exposure times, and results at longer exposure times suggest that the surface is greater than 30% void. This is qualitatively verified by the AFM images.

  16. Oxygen plasma surface modification enhances immobilization of simvastatin acid.

    PubMed

    Yoshinari, Masao; Hayakawa, Tohru; Matsuzaka, Kenichi; Inoue, Takashi; Oda, Yutaka; Shimono, Masaki; Ide, Takaharu; Tanaka, Teruo

    2006-02-01

    Simvastatin acid (SVA) has been reported to stimulate bone formation with increased expression of BMP-2. Therefore, immobilization of SVA onto dental implants is expected to promote osteogenesis at the bone tissue/implant interface. The aim of this study was to evaluate the immobilization behavior of SVA onto titanium (Ti), O(2)-plasma treated titanium (Ti + O(2)), thin-film coatings of hexamethyldisiloxane (HMDSO), and O(2)-plasma treated HMDSO (HMDSO + O(2)) by using the quartz crystal microbalance-dissipation (QCM-D) technique. HMDSO surfaces were activated by the introduction of an OH group and/or O(2)-functional groups by O(2)-plasma treatment. In contrast, titanium surfaces showed no appreciable compositional changes by O(2)-plasma treatment. The QCM-D technique enabled evaluation even at the adsorption behavior of a substance with a low molecular weight such as simvastatin. The largest amount of SVA was adsorbed on O(2)-plasma treated HMDSO surfaces compared to untreated titanium, HMDSO-coated titanium, and O(2)-plasma treated titanium. These findings suggested that the adsorption of SVA was enhanced on more hydrophilic surfaces concomitant with the presence of an OH group and/or O(2)-functional group resulting from the O(2)-plasma treatment, and that an organic film of HMDSO followed by O(2)-plasma treatment is a promising method for the adsorption of SVA in dental implant systems. PMID:16543663

  17. Relationship between the discharge mode and the spatial oxygen plasma distribution in a large size ferrite inductively coupled plasmas

    SciTech Connect

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

    2015-04-15

    The electrical characteristics and the spatial distribution of oxygen plasma according to the number of turns in ferrite inductively coupled plasmas (ferrite ICPs) are investigated. Through a new ICP model, which includes the capacitive coupling and the power loss of the ferrite material with the conventional ICP model, the variation of the oxygen discharge characteristics depending on the number of turns is simply understood by the electrical measurement, such as the antenna voltages and the currents. As the number of the turns increases, the capacitive coupling dominantly affects the spatial plasma distribution. This capacitive coupling results in a center focused density profile along the radial direction. In spite of the same discharge conditions (discharge chamber, neutral gas, and pressure), the spatial plasma distribution over 450 mm has drastic changes by increasing number of the turns. In addition, the effect of the negative species to the density profile is compared with the argon discharge characteristics at the same discharge configuration.

  18. Plasma corticosteroid dynamics in channel catfish, Ictalurus punctatus (Rafinesque), during and after oxygen depletion

    USGS Publications Warehouse

    Tomasso J.R., Davis, K. B.; Parker, N.C.

    1981-01-01

    Plasma corticosteroid concentrations in channel catfish, Ictalurus punctatus, (normally 1.0 ± 0.3 μg/100 ml) increased significantly (to 5.9 ± 1.2μg/100 ml) in response to acute oxygen depletion and then returned to control levels within 30 min after the dissolved oxygen concentration was increased; however, a secondary increase in plasma corticosteroid levels was observed 6 h after exposure. Corticosteroid levels also increased in fish exposed to dissolved oxygen concentration of <0.2 mg/1 for three days. Methylene blue was not effective in preventing interrenal response to low dissolved oxygen. No diurnal plasma corticosteroid rhythm was observed in fish exposed to diurnal chemical rhythms of culture ponds.

  19. Sensitivity enhancement of carbon nanotube based ammonium ion sensors through surface modification by using oxygen plasma treatment

    SciTech Connect

    Yeo, Sanghak; Woong Jang, Chi; Lee, Seok; Min Jhon, Young; Choi, Changrok

    2013-02-18

    We have shown that the sensitivity of carbon nanotube (CNT) based sensors can be enhanced as high as 74 times through surface modification by using the inductively coupled plasma chemical vapor deposition method with oxygen. The plasma treatment power was maintained as low as 10 W within 20 s, and the oxygen plasma was generated far away from the sensors to minimize the plasma damage. From X-ray photoelectron spectroscopy analysis, we found that the concentration of oxygen increased with the plasma treatment time, which implies that oxygen functional groups or defect sites were generated on the CNT surface.

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

    DOE PAGESBeta

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

    2016-01-01

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

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

    NASA Astrophysics Data System (ADS)

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

    2016-04-01

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

  2. Nonthermal Radiation Processes in Interplanetary Plasmas

    NASA Astrophysics Data System (ADS)

    Chian, A. C. L.

    1990-11-01

    RESUMEN. En la interacci6n de haces de electrones energeticos con plasmas interplanetarios, se excitan ondas intensas de Langmuir debido a inestabilidad del haz de plasma. Las ondas Langmuir a su vez interaccio nan con fluctuaciones de densidad de baja frecuencia para producir radiaciones. Si la longitud de las ondas de Langmujr exceden las condicio nes del umbral, se puede efectuar la conversi5n de modo no lineal a on- das electromagneticas a traves de inestabilidades parametricas. As se puede excitar en un plasma inestabilidades parametricas electromagneticas impulsadas por ondas intensas de Langmuir: (1) inestabilidades de decaimiento/fusi5n electromagnetica impulsadas por una bomba de Lang- muir que viaja; (2) inestabilidades dobles electromagneticas de decai- miento/fusi5n impulsadas por dos bombas de Langrnuir directamente opues- tas; y (3) inestabilidades de dos corrientes oscilatorias electromagne- ticas impulsadas por dos bombas de Langmuir de corrientes contrarias. Se concluye que las inestabilidades parametricas electromagneticas in- ducidas por las ondas de Langmuir son las fuentes posibles de radiacio- nes no termicas en plasmas interplanetarios. ABSTRACT: Nonthermal radio emissions near the local electron plasma frequency have been detected in various regions of interplanetary plasmas: solar wind, upstream of planetary bow shock, and heliopause. Energetic electron beams accelerated by solar flares, planetary bow shocks, and the terminal shock of heliosphere provide the energy source for these radio emissions. Thus, it is expected that similar nonthermal radiation processes may be responsible for the generation of these radio emissions. As energetic electron beams interact with interplanetary plasmas, intense Langmuir waves are excited due to a beam-plasma instability. The Langmuir waves then interact with low-frequency density fluctuations to produce radiations near the local electron plasma frequency. If Langmuir waves are of sufficiently large

  3. Dynamics of a pulsed laser generated tin plasma expanding in an oxygen atmosphere

    NASA Astrophysics Data System (ADS)

    Barreca, F.; Fazio, E.; Neri, F.; Barletta, E.; Trusso, S.; Fazio, B.

    2005-10-01

    Semiconducting tin oxide can be successfully deposited by means of the laser ablation technique. In particular by ablating metallic tin in a controlled oxygen atmosphere, thin films of SnOx have been deposited. The partial oxygen pressure at which the films are deposited strongly influences both the stoichiometry and the structural properties of the films. In this work, we present a study of the expansion dynamics of the plasma generated by ablating a tin target by means of a pulsed laser using time and space resolved optical emission spectroscopy and fast photography imaging of the expanding plasma. Both Sn I and Sn II optical emission lines have been observed from the time-integrated spectroscopy. Time resolved-measurements revealed the dynamics of the expanding plasma in the ambient oxygen atmosphere. Stoichiometry of the films has been determined by means of X-ray photoelectron spectroscopy and correlated to the expansion dynamics of the plasma.

  4. Effects of oxygen radicals in low-pressure surface-wave plasma on sterilization

    SciTech Connect

    Nagatsu, Masaaki; Terashita, Fumie; Nonaka, Hiroyuki; Xu, Lei; Nagata, Toshi; Koide, Yukio

    2005-05-23

    The effects of oxygen radicals on sterilization were studied using a 2.45 GHz surface-wave oxygen plasma. A population of 1.5x10{sup 6} Bacillus stearothermophilus spores was irradiated for 3 min or more with oxygen plasma, generated at pressures between 6 and 14 Pa. The decimal reduction value (D value), a measure of the effectiveness of sterilization, was determined to be about 15-25 s. Using only oxygen radicals, excluding all charged particles, the 1.5x10{sup 6} spores were sterilized with a D value of 30-45 s after 5 min or more of irradiation. On scanning electron microscopy, the length and width of the spores changed significantly due to chemical etching by oxygen radicals.

  5. Effects of oxygen radicals in low-pressure surface-wave plasma on sterilization

    NASA Astrophysics Data System (ADS)

    Nagatsu, Masaaki; Terashita, Fumie; Nonaka, Hiroyuki; Xu, Lei; Nagata, Toshi; Koide, Yukio

    2005-05-01

    The effects of oxygen radicals on sterilization were studied using a 2.45GHz surface-wave oxygen plasma. A population of 1.5×106 Bacillus stearothermophilus spores was irradiated for 3min or more with oxygen plasma, generated at pressures between 6 and 14Pa. The decimal reduction value (D value), a measure of the effectiveness of sterilization, was determined to be about 15-25s. Using only oxygen radicals, excluding all charged particles, the 1.5×106 spores were sterilized with a D value of 30-45s after 5min or more of irradiation. On scanning electron microscopy, the length and width of the spores changed significantly due to chemical etching by oxygen radicals.

  6. Automation and control of off-planet oxygen production processes

    NASA Technical Reports Server (NTRS)

    Marner, W. J.; Suitor, J. W.; Schooley, L. S.; Cellier, F. E.

    1990-01-01

    This paper addresses several aspects of the automation and control of off-planet production processes. First, a general approach to process automation and control is discussed from the viewpoint of translating human process control procedures into automated procedures. Second, the control issues for the automation and control of off-planet oxygen processes are discussed. Sensors, instruments, and components are defined and discussed in the context of off-planet applications, and the need for 'smart' components is clearly established.

  7. Combined effect of protein and oxygen on reactive oxygen and nitrogen species in the plasma treatment of tissue

    NASA Astrophysics Data System (ADS)

    Gaur, Nishtha; Szili, Endre J.; Oh, Jun-Seok; Hong, Sung-Ha; Michelmore, Andrew; Graves, David B.; Hatta, Akimitsu; Short, Robert D.

    2015-09-01

    The influence of protein and molecular, ground state oxygen (O2) on the plasma generation, and transport of reactive oxygen and nitrogen species (RONS) in tissue are investigated. A tissue target, comprising a 1 mm thick gelatin film (a surrogate for real tissue), is placed on top of a 96-well plate; each well is filled with phosphate buffered saline (PBS, pH 7.4) containing one fluorescent or colorimetric reporter that is specific for one of three RONS (i.e., H2O2, NO2-, or OH•) or a broad spectrum reactive oxygen species reporter (2,7-dichlorodihydrofluorescein). A helium cold atmospheric plasma (CAP) jet contacts the top of the gelatin surface, and the concentrations of RONS generated in PBS are measured on a microplate reader. The data show that H2O2, NO2-, or OH• are generated in PBS underneath the target. Independently, measurements are made of the O2 concentration in the PBS with and without the gelatin target. Adding bovine serum albumin protein to the PBS or gelatin shows that protein either raises or inhibits RONS depending upon the O2 concentration. Our results are discussed in the context of plasma-soft tissue interactions that are important in the development of CAP technology for medicine, biology, and food manufacturing.

  8. Low temperature oxidation of silicon in a microwave-discharged oxygen plasma

    SciTech Connect

    Kimura, S.I.; Miyake, K.; Murakami, E.; Sunami, H.; Tokuyama, T.; Warabisako, T.

    1985-06-01

    Silicon dioxide growth in an oxygen plasma is investigated using newly developed microwave discharge equipment with electron cyclotron resonance. It is found that the plasma oxidation kinetics can be explained by the Cabrera-Mott model, in which the drift motion of ions is assumed, rather than by the Deal-Grove thermal oxidation model. The drift motion of oxygen ions across the oxide film under the influence of self-bias in the plasma is considered to be the plasma oxidation mechanism. Infrared absorption and etch-rate measurements reveal that the physica properties of plasma oxidized SiO/sub 2/ at 600/sup 0/C are structurally quite comparable to those of thermally oxidized SiO/sub 2/.

  9. Plasma-Engraved Co3 O4 Nanosheets with Oxygen Vacancies and High Surface Area for the Oxygen Evolution Reaction.

    PubMed

    Xu, Lei; Jiang, Qianqian; Xiao, Zhaohui; Li, Xingyue; Huo, Jia; Wang, Shuangyin; Dai, Liming

    2016-04-18

    Co3 O4 , which is of mixed valences Co(2+) and Co(3+) , has been extensively investigated as an efficient electrocatalyst for the oxygen evolution reaction (OER). The proper control of Co(2+) /Co(3+) ratio in Co3 O4 could lead to modifications on its electronic and thus catalytic properties. Herein, we designed an efficient Co3 O4 -based OER electrocatalyst by a plasma-engraving strategy, which not only produced higher surface area, but also generated oxygen vacancies on Co3 O4 surface with more Co(2+) formed. The increased surface area ensures the Co3 O4 has more sites for OER, and generated oxygen vacancies on Co3 O4 surface improve the electronic conductivity and create more active defects for OER. Compared to pristine Co3 O4 , the engraved Co3 O4 exhibits a much higher current density and a lower onset potential. The specific activity of the plasma-engraved Co3 O4 nanosheets (0.055 mA cm(-2) BET at 1.6 V) is 10 times higher than that of pristine Co3 O4 , which is contributed by the surface oxygen vacancies. PMID:26990905

  10. PLASMA EMISSION BY WEAK TURBULENCE PROCESSES

    SciTech Connect

    Ziebell, L. F.; Gaelzer, R.; Yoon, P. H.; Pavan, J. E-mail: rudi.gaelzer@ufrgs.br E-mail: joel.pavan@ufpel.edu.br

    2014-11-10

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

  11. Secondary photon emission in plasma processing

    SciTech Connect

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

    1997-05-01

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

  12. Influence of oxygen in atmospheric-pressure argon plasma jet on sterilization of Bacillus atrophaeous spores

    SciTech Connect

    Lim, Jin-Pyo; Uhm, Han S.; Li, Shou-Zhe

    2007-09-15

    A nonequilibrium Ar/O{sub 2} plasma discharge at atmospheric pressure was carried out in a coaxial cylindrical reactor with a stepped electrode configuration powered by a 13.56 MHz rf power supplier. The argon glow discharge with high electron density produces oxygen reactive species in large quantities. Argon plasma jets penetrate deep into ambient air and create a path for oxygen radicals to sterilize microbes. A sterilization experiment with bacterial endospores indicates that an argon-oxygen plasma jet very effectively kills endospores of Bacillus atrophaeus (ATCC 9372), thereby demonstrating its capability to clean surfaces and its usefulness for reinstating contaminated equipment as free from toxic biological warfare agents. The decimal reduction time (D values) of the Ar/O{sub 2} plasma jet at an exposure distance of 0.5-1.5 cm ranges from 5 to 57 s. An actinometric comparison of the sterilization data shows that atomic oxygen radicals play a significant role in plasma sterilization. When observed under a scanning electron microscope, the average size of the spores appears to be greatly reduced due to chemical reactions with the oxygen radicals.

  13. Helium/oxygen atmospheric pressure plasma jet treatment for hydrophilicity improvement of grey cotton knitted fabric

    NASA Astrophysics Data System (ADS)

    Tian, Liqiang; Nie, Huali; Chatterton, Nicholas P.; Branford-White, Christopher J.; Qiu, Yiping; Zhu, Limin

    2011-06-01

    The influence of atmospheric pressure plasma jet (APPJ) treatment on the hydrophilicity of grey cotton knitted fabric (GCKF) was investigated. For comparison, specimens which had undergone different treatments were tested by contact angle measurement, scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS), fourier-transform infrared attenuated total reflectance spectroscopy (FTIR-ATR) and X-ray diffraction (XRD). The results imply that helium/oxygen APPJ could improve the hydrophilicity of GCKF by modifying the surface properties. In addition, combining dewaxing processes with He/O 2 APPJ treatment was found to tremendously improve the hydrophilicity of GCKF. The mechanism of this was also confirmed by Ruthenium Red staining which showed most of pectic substances inside the cotton fiber existed beneath the waxy layer and on top of the cellulose microfibril.

  14. Optical Properties of Oxygen Plasma-Treated Carbon Nanowalls Grown on Glass Substrates.

    PubMed

    Jung, Yong Ho; Choi, Won Seok

    2016-05-01

    In this paper, we investigated the effect of oxygen (02) plasma treatment on a synthesized carbon nanowall (CNW). A microwave plasma-enhanced chemical vapor deposition (PECVD) system was facilitated to grow CNWs on a glass, using a mixture of CH4 and H2 gases. First, the CNWs were post-plasma-treated for different treatment durations, and then their optical properties were analyzed. In addition, the cross-sectional and planar images of the CNWs were examined via field-emission scanning electron microscopy (FE-SEM) depending on the different post-plasma-treatment durations. Then the structural characteristics were analyzed via Raman spectroscopy, and the changes in the light transmittance depending on the O2 plasma treatment durations were analyzed using UV-Vis spectroscopy. The effects of the post-plasma treatments on the synthesized CNWs were evaluated. The results confirmed that O2 gas is effective for plasma etching of CNWs. PMID:27483919

  15. Solar terrestrial coupling through space plasma processes

    SciTech Connect

    Birn, J.

    2000-12-01

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

  16. The influence of substrate material on bacteria sterilization in an oxygen plasma glow discharge

    NASA Astrophysics Data System (ADS)

    Cvelbar, U.; Vujosevic, D.; Vratnica, Z.; Mozetic, M.

    2006-08-01

    A critical approach to plasma sterilization is presented with the aim of sterilizing biocompatible materials such as TiO2 and polymer implants. Oxygen plasma was applied to sterilize glass and aluminium samples containing Bacillus subtilis spores. Sterilization was performed with a low pressure weakly ionized oxygen plasma created with a RF generator with an output power of 300 W and frequency 27.12 MHz. The density of charged particles, density of neutral oxygen atoms and the electron temperature were about 1 × 1016 m-3, 1.5 × 1022 m-3 and 5 eV, respectively. The sterilization effects were observed by SEM and by bacterial cultivation. It was found that the surface recombination of O-atoms plays an important role, since it causes temperature changes in the substrate. The sterilization efficiency increased with increasing plasma exposure time. The results showed that the sterilization efficiency is not necessarily just the effect of oxygen plasma radical interactions, but also of the sample heating due to radical interaction with the substrate. Plasma sterilization should be done differently according to the substrate material used for sterilization.

  17. Processing of metal and oxygen from lunar deposits

    NASA Technical Reports Server (NTRS)

    Acton, Constance F.

    1992-01-01

    On the moon, some whole rocks may be ores for abundant elements, such as oxygen, but beneficiation will be important if metallic elements are sought from raw lunar dirt. In the extraction process, a beneficiated metallic ore, such as an oxide, sulfide, carbonate, or silicate mineral, is converted to reduced metal. A variety of plausible processing technologies, which includes recovery of meteoritic iron, and processing of lunar ilmenite, are described in this report.

  18. Process for conversion of lignin to reformulated, partially oxygenated gasoline

    DOEpatents

    Shabtai, Joseph S.; Zmierczak, Wlodzimierz W.; Chornet, Esteban

    2001-01-09

    A high-yield process for converting lignin into reformulated, partially oxygenated gasoline compositions of high quality is provided. The process is a two-stage catalytic reaction process that produces a reformulated, partially oxygenated gasoline product with a controlled amount of aromatics. In the first stage of the process, a lignin feed material is subjected to a base-catalyzed depolymerization reaction, followed by a selective hydrocracking reaction which utilizes a superacid catalyst to produce a high oxygen-content depolymerized lignin product mainly composed of alkylated phenols, alkylated alkoxyphenols, and alkylbenzenes. In the second stage of the process, the depolymerized lignin product is subjected to an exhaustive etherification reaction, optionally followed by a partial ring hydrogenation reaction, to produce a reformulated, partially oxygenated/etherified gasoline product, which includes a mixture of substituted phenyl/methyl ethers, cycloalkyl methyl ethers, C.sub.7 -C.sub.10 alkylbenzenes, C.sub.6 -C.sub.10 branched and multibranched paraffins, and alkylated and polyalkylated cycloalkanes.

  19. Plasma processing of low-k dielectrics

    SciTech Connect

    Baklanov, Mikhail R.; Marneffe, Jean-Francois de; Shamiryan, Denis; Urbanowicz, Adam M.; Shi Hualiang; Rakhimova, Tatyana V.; Huang Huai; Ho, Paul S.

    2013-01-28

    This paper presents an in-depth overview of the present status and novel developments in the field of plasma processing of low dielectric constant (low-k) materials developed for advanced interconnects in ULSI technology. The paper summarizes the major achievements accomplished during the last 10 years. It includes analysis of advanced experimental techniques that have been used, which are most appropriate for low-k patterning and resist strip, selection of chemistries, patterning strategies, masking materials, analytical techniques, and challenges appearing during the integration. Detailed discussions are devoted to the etch mechanisms of low-k materials and their degradation during the plasma processing. The problem of k-value degradation (plasma damage) is a key issue for the integration, and it is becoming more difficult and challenging as the dielectric constant of low-k materials scales down. Results obtained with new experimental methods, like the small gap technique and multi-beams systems with separated sources of ions, vacuum ultraviolet light, and radicals, are discussed in detail. The methods allowing reduction of plasma damage and restoration of dielectric properties of damaged low-k materials are also discussed.

  20. Cold atmospheric pressure plasma jets as sources of singlet delta oxygen for biomedical applications

    SciTech Connect

    Sousa, J. S.; Niemi, K.; Cox, L. J.; Algwari, Q. Th.; Gans, T.; O'Connell, D.

    2011-06-15

    Absolute densities of singlet delta oxygen (SDO) molecules were measured using infrared optical emission spectroscopy in the flowing effluents of two different atmospheric-pressure plasma jets (APPJs): a capacitively coupled radio-frequency-driven jet (rf-APPJ) and a lower frequency kilohertz-driven dielectric barrier discharge jet. The plasma jets were operated in helium, with small admixtures of molecular oxygen (O{sub 2} < 2%). High absolute SDO densities of up to 6.2 x 10{sup 15} cm{sup -3} were measured at approximately 10 cm downstream. The rf-APPJ seems to be much more efficient in producing SDO. The influence of different parameters, such as gas flows and mixtures and power coupled to the plasmas, on the production of SDO by the two APPJs has been investigated. Despite the considerable differences between the two plasma jets (excitation frequency, electric field direction, inter-electrode distance, plasma propagation), similar dependencies on the oxygen admixture and on the dissipated power were found in both APPJs. However, opposite trends were observed for the gas flow dependence. The results presented in this paper show that the control of the external operating conditions of each APPJ enables the tailoring of the SDO composition of both plasma effluents. This provides scope to tune the plasma jets for desired applications, e.g., in biomedicine.

  1. Influence of oxygen traces on an atmospheric-pressure radio-frequency capacitive argon plasma discharge

    SciTech Connect

    Li Shouzhe; Wu Qi; Yan Wen; Wang Dezhen; Uhm, Han S.

    2011-10-15

    An atmospheric-pressure capacitive discharge source driven by radio-frequency power supply at 13.56 MHz has been developed experimentally that is capable of producing a homogeneous and cold glow discharge in O{sub 2}/Ar. With respect to the influence of oxygen component when diluted into argon plasma discharge on the discharge characteristics, the measurements of the electrical parameters (impedance, phase angle, resistance, and reactance) are made systematically and the densities of the metastable and resonant state of argon are determined by means of optical emission spectroscopy (OES). It is shown that the admixture of oxygen into argon plasma not only changes the electric characteristics but also alters the optical emission spectra greatly due to strong interaction between the oxygen content and the argon in the plasma environment.

  2. Modeling of the vacuum plasma spray process

    SciTech Connect

    Varacalle, D.J. Jr. ); Neiser, R.A.; Smith, M.F. )

    1992-01-01

    Experimental and analytical studies have been conducted to investigate gas, particle, and coating dynamics in the vacuum plasma spray (VPS) process for a tungsten powder. VPS coatings were examined metallographically and the results compared with the model's predictions. The plasma was numerically modeled from the cathode tip to the spray distance in the free plume for the experimental conditions of this study. This information was then used as boundary conditions to solve the particle dynamics. The predicted temperature and velocity of the powder particles at standoff were then used as initial conditions for a coating dynamics code. The code predicts the coating morphology for the specific process parameters. The predicted characteristics exhibit good correlation with the observed coating properties.

  3. Modeling of the vacuum plasma spray process

    SciTech Connect

    Varacalle, D.J. Jr.; Neiser, R.A.; Smith, M.F.

    1992-10-01

    Experimental and analytical studies have been conducted to investigate gas, particle, and coating dynamics in the vacuum plasma spray (VPS) process for a tungsten powder. VPS coatings were examined metallographically and the results compared with the model`s predictions. The plasma was numerically modeled from the cathode tip to the spray distance in the free plume for the experimental conditions of this study. This information was then used as boundary conditions to solve the particle dynamics. The predicted temperature and velocity of the powder particles at standoff were then used as initial conditions for a coating dynamics code. The code predicts the coating morphology for the specific process parameters. The predicted characteristics exhibit good correlation with the observed coating properties.

  4. Optimizing the synthesis of vanadium-oxygen nanostructures by plasma plume dynamics using optical imaging

    NASA Astrophysics Data System (ADS)

    Masina, Bathusile N.; Lafane, Slimane; Wu, Lorinda; Abdelli-Messaci, Samira; Kerdja, Tahar; Forbes, Andrew

    2015-03-01

    The effect of an oxygen atmosphere on the expansion dynamics of a laser-produced vanadium-oxygen plasma has been investigated using a fast intensified charged-coupled device camera. We find regimes of the plasma plume expansion ranging from a free plume at vacuum and low oxygen pressures, through collisional and shock-wave-like hydrodynamic regimes at intermediate oxygen pressure, finally reaching a confined plume with subsequent thermalization of the plume particles at the highest pressure of the oxygen gas. Vanadium oxide nanostructures thin films were synthesized from this plasma and the resulting vanadium oxide phases studied as a function of the plume dynamics. We found monoclinic vanadium dioxide (VO2) (M1) and VO2 (B) nanoparticles in thin films deposited at 0.05 mbar. Pure phases of vanadium trioxide (V2O3) smooth and pentoxide (V2O5) nanorods thin films were detected at 0.01 and 0.1 to 0.2 mbar, respectively. Thin films containing VO2 (M1) were found to have a reversible metal-to-insulator transition at 61°C. This work paves the way to VO phase control by judicious choice of laser and plasma conditions.

  5. Deposition of Lanthanum Strontium Cobalt Ferrite (LSCF) Using Suspension Plasma Spraying for Oxygen Transport Membrane Applications

    NASA Astrophysics Data System (ADS)

    Fan, E. S. C.; Kesler, O.

    2015-08-01

    Suspension plasma spray deposition was utilized to fabricate dense lanthanum strontium cobalt ferrite oxygen separation membranes (OSMs) on porous metal substrates for mechanical support. The as-sprayed membranes had negligible and/or reversible material decomposition. At the longer stand-off distance (80 mm), smooth and dense membranes could be manufactured using a plasma with power below approximately 81 kW. Moreover, a membrane of 55 μm was observed to have very low gas leakage rates desirable for OSM applications. This thickness could potentially be decreased further to improve oxygen diffusion by using metal substrates with finer surface pores.

  6. Modification of the Surface Properties of Polyimide Films using POSS Deposition and Oxygen Plasma Exposure

    NASA Technical Reports Server (NTRS)

    Wohl, Christopher J.; Belcher, Marcus A.; Ghose, Sayata; Connell, John W.

    2008-01-01

    Topographically rich surfaces were generated by spray-coating organic solutions of a polyhedral oligomeric silsesquioxane, octakis (dimethylsilyloxy) silsesquioxane (POSS), on Kapton HN films and exposing them to radio frequency generated oxygen plasma. Changes in both surface chemistry and topography were observed. High-resolution scanning electron microscopy indicated substantial modification of the POSS-coated polyimide surface topographies as a result of oxygen plasma exposure. Water contact angles varied from 104 deg for unexposed POSS-coated surfaces to approximately 5 deg, for samples exposed for 5 h. Modulation of the dispersive and polar contributions to the surface energy was determined using van Oss Good Chaudhury theory.

  7. Surface characterization and adhesion of oxygen plasma-modified LARC-TPI

    NASA Technical Reports Server (NTRS)

    Chin, J. W.; Wightman, J. P.

    1992-01-01

    LARC-TPI, an aromatic thermoplastic polyimide, was exposed to an oxygen plasma as a surface pretreatment for adhesive bonding. Chemical and physical changes which occurred in the polyimide surface as a result of the plasma treatment were investigated using X-ray photoelectron spectroscopy (XPS), infrared reflection-absorption spectroscopy (IR-RAS), contact-angle analysis, ellipsometry, and high resolution SEM. A 180-deg peel test with an acrylate-based pressure sensitive adhesive as a flexible adherent was utilized to study the interactions of the plasma-treated polyimide surface with other polymeric materials. The surface characterization and adhesion testing results showed that the oxygen plasma treatment, while creating a more hydrophilic, polar surface, also caused chain scission, resulting in the formation of a weak boundary layer which inhibited adhesion.

  8. Magnetic-field-dependent plasma composition of a pulsed aluminum arc in an oxygen ambient

    NASA Astrophysics Data System (ADS)

    Schneider, Jochen M.; Anders, André; Yushkov, George Yu.

    2001-01-01

    A variety of plasma-based deposition techniques utilize magnetic fields to affect the degree of ionization as well as for focusing and guiding of plasma beams. Here we use time-of-flight charge-to-mass spectrometry to describe the effect of a magnetic field on the plasma composition of a pulsed Al plasma stream in an ambient containing intentionally introduced oxygen as well as for high vacuum conditions typical residual gas. The plasma composition evolution was found to be strongly dependent on the magnetic field strength and can be understood by invoking two electron impact ionization routes: ionization of the intentionally introduced gas as well as ionization of the residual gas. These results are characteristic of plasma-based techniques where magnetic fields are employed in a high-vacuum ambient. In effect, the impurity incorporation during reactive thin-film growth pertains to the present findings.

  9. Physical processes in spin polarized plasmas

    SciTech Connect

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

    1984-05-01

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

  10. Competitive Low Pressure Oxygen Plasma Interactions with Different= Carbon-Carbon Double Bonds

    NASA Astrophysics Data System (ADS)

    Patiño, P.; Sifontes, A.; Gambús, G.

    1999-10-01

    Recently we have shown advances from reactions of O(^3P) with both, l ong-chain hydrocarbons and refinery residuum. The oxidation products of t he process, a mixture of alcohols, epoxides and carbonyl compounds, might have potential properties as additives in formulating fuels. This work s hows the results of the interactions of an oxygen plasma with double bond s, both olefin and aromatic, in the same compound. The reactions have bee n carried out by making the plasma, created by a high voltage glow discha rge, reach the low vapor pressure surface of liquid 4-phenyl-1-butene. Th is (3 mL) was cooled down to -45 ^oC in a glass reactor, applied power was 24 W, at an oxygen pressure of 20 Pa. Products were analyzed by IR, N MR and mass spectroscopies. Conversions were studied as a function of the reaction time, this ranging from 5 to 120 minutes. At short times the O( ^3P) atoms produced in the discharge only reacted with the alkene fra ction of the hydrocarbon, 4-phenyl-1,2-epoxibutane (52%) and 4-phenyl-bu tanal (48%) being the products. Reactions on the benzene ring were obser ved from about 30 minutes on, the corresponding phenols having being prod uced at ratios ortho:para:meta :: 4:1:0.7. At 120 minutes, the ol efin have been completely oxidized and a low fraction of the non-equivale nt two methylene groups have reacted to produce alcohols and ketones.

  11. Method for minimizing decarburization and other high temperature oxygen reactions in a plasma sprayed material

    DOEpatents

    Lenling, William J.; Henfling, Joseph A.; Smith, Mark F.

    1993-06-08

    A method is disclosed for spray coating material which employs a plasma gun that has a cathode, an anode, an arc gas inlet, a first powder injection port, and a second powder injection port. A suitable arc gas is introduced through the arc gas inlet, and ionization of the arc gas between the cathode and the anode forms a plasma. The plasma is directed to emenate from an open-ended chamber defined by the boundary of the anode. A coating is deposited upon a base metal part by suspending a binder powder within a carrier gas that is fed into the plasma through the first powder injection port; a material subject to degradation by high temperature oxygen reactions is suspended within a carrier gas that is fed into the plasma through the second injection port. The material fed through the second injection port experiences a cooler portion of the plasma and has a shorter dwell time within the plasma to minimize high temperature oxygen reactions. The material of the first port and the material of the second port intermingle within the plasma to form a uniform coating having constituent percentages related to the powder-feed rates of the materials through the respective ports.

  12. Effect of oxygen on the conversion of acetaldehyde in homogeneous plasmas of N2/O2/CH3CHO mixtures

    NASA Astrophysics Data System (ADS)

    Faider, W.; Pasquiers, S.; Blin-Simiand, N.; Magne, L.

    2013-12-01

    A photo-triggered discharge producing a homogeneous plasma was used to investigate, experimentally and with the help of a self-consistent 0D model, the decomposition processes of acetaldehyde (concentration up to 0.5%) in N2/O2/CH3CHO mixtures containing up to 20% oxygen, at a total pressure of 460 mbar. This work follows a previous one about N2/CH3CHO, having provided the necessary data about the quenching of the N2 metastable states by the acetaldehyde molecule. For the condition of the experiment, it was shown that oxygen has a weak influence on the acetaldehyde removal. Nevertheless, the kinetic reactions involved drastically change when the oxygen percentage is increased. Quenching reactions gradually give way to oxidation reactions by O(3P) and OH. Oxidation by OH dominates for a high acetaldehyde concentration or a high oxygen percentage. Moreover, CH3 is an important primary compound for the formation of CH4 and C2H6. Ethane is less populated than methane in the whole range of oxygen percentage values studied, and there are still hydrocarbon molecules in the gas mixture at 20% oxygen. This is well explained by the adopted kinetic scheme.

  13. Two-dimensional lateral heterojunction through bandgap engineering of MoS2 via oxygen plasma.

    PubMed

    Choudhary, Nitin; Islam, Muhammad R; Kang, Narae; Tetard, Laurene; Jung, Yeonwoong; Khondaker, Saiful I

    2016-09-14

    The present study explores the structural, optical (photoluminescence (PL)), and electrical properties of lateral heterojunctions fabricated by selective exposure of mechanically exfoliated few layer two-dimensional (2D) molybdenum disulfide (MoS2) flakes under oxygen (O2)-plasma. Raman spectra of the plasma exposed MoS2 flakes show a significant loss in the structural quality due to lattice distortion and creation of oxygen-containing domains in comparison to the pristine part of the same flake. The PL mapping evidences the complete quenching of peak A and B consistent with a change in the exciton states of MoS2 after the plasma treatment, indicating a significant change in its band gap properties. The electrical transport measurements performed across the pristine and the plasma-exposed MoS2 flake exhibit a gate tunable current rectification behavior with a rectification ratio up to 1.3  ×  10(3) due to the band-offset at the pristine and plasma-exposed MoS2 interface. Our Raman, PL, and electrical transport data confirm the formation of an excellent lateral heterojunction in 2D MoS2 through its bandgap modulation via oxygen plasma. PMID:27392099

  14. Two-dimensional lateral heterojunction through bandgap engineering of MoS2 via oxygen plasma

    NASA Astrophysics Data System (ADS)

    Choudhary, Nitin; Islam, Muhammad R.; Kang, Narae; Tetard, Laurene; Jung, Yeonwoong; Khondaker, Saiful I.

    2016-09-01

    The present study explores the structural, optical (photoluminescence (PL)), and electrical properties of lateral heterojunctions fabricated by selective exposure of mechanically exfoliated few layer two-dimensional (2D) molybdenum disulfide (MoS2) flakes under oxygen (O2)-plasma. Raman spectra of the plasma exposed MoS2 flakes show a significant loss in the structural quality due to lattice distortion and creation of oxygen-containing domains in comparison to the pristine part of the same flake. The PL mapping evidences the complete quenching of peak A and B consistent with a change in the exciton states of MoS2 after the plasma treatment, indicating a significant change in its band gap properties. The electrical transport measurements performed across the pristine and the plasma-exposed MoS2 flake exhibit a gate tunable current rectification behavior with a rectification ratio up to 1.3  ×  103 due to the band-offset at the pristine and plasma-exposed MoS2 interface. Our Raman, PL, and electrical transport data confirm the formation of an excellent lateral heterojunction in 2D MoS2 through its bandgap modulation via oxygen plasma.

  15. Inactivation of Pathogenic Bacteria on Seeds by Active Oxygen Species Generated in Low-Pressure Plasma

    NASA Astrophysics Data System (ADS)

    Ono, Reoto; Uchida, Shohei; Hayashi, Nobuya; Kosaka, Rina; Soeda, Yasutaka

    2015-09-01

    The inactivation of bacteria on seeds by active oxygen species generated by a low-pressure oxygen plasma is investigated. Species of active oxygen contributing to the inactivation of bacteria are attempted to be identified. Cylindrical stainless chamber with the internal volume of 17 L is used and RF antenna is set inside the chamber. The oxygen gas pressure is 20-100 Pa. RF power of 13.56 MHz is supplied to RF antenna and CCP is generated. After irradiation, bacteria are extracted from seeds and cultivated on nutrient agars. The number of colonies on these agars is counted after 48 h incubation. The number of bacteria on seeds decreases to less than 10-3 after plasma irradiation for 45 min comparing with that of control. The tendency of the reduction rate of bacteria on seeds has positive correlation with that of the light emission intensity of the singlet excited oxygen molecule as the oxygen gas pressure is varied. It is supposed that the singlet excited oxygen molecule would be one of the major factors for the inactivation of bacteria on seeds.

  16. Automated Plasma Spray (APS) process feasibility study

    NASA Technical Reports Server (NTRS)

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

    1981-01-01

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

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

    SciTech Connect

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

    2008-01-01

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

  18. Atomic processes in high temperature plasmas

    SciTech Connect

    Hahn, Y.

    1991-07-01

    This is the final report on the project Atomic Processes in High Temperature Plasmas', which has been completed in June 30, 1991. The original contract started in 1978. The dielectronic recombination (DR) rate coefficients were calculated for ions with the number of electrons N = 1, 2, 3, 4, 5, 10, 11, and 12. The result was then used to construct a new and improved rate formula. Other important resonant processes, which are closely related to DR, were also studied to interpret experiments and to test the DR theory. The plasma field and the density effects on the rate coefficients was found to be important, and a consistent correction procedure is being developed. The available data on the DR rates and their accuracy do not yet fully meet the requirement for plasma modeling; there are serious gaps in the available data, and the currently adopted theoretical procedure needs improvements. Critical assessment of the current status of the DR problem is presented, and possible future work needed is summarized.

  19. Current problems in plasma spray processing

    SciTech Connect

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

    1991-12-31

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

  20. Current problems in plasma spray processing

    SciTech Connect

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

    1991-01-01

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

  1. Automated process control for plasma etching

    NASA Astrophysics Data System (ADS)

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

    1992-06-01

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

  2. Hierarchical regrowth of flowerlike nanographene sheets on oxygen-plasma-treated carbon nanowalls

    NASA Astrophysics Data System (ADS)

    Shimoeda, Hironao; Kondo, Hiroki; Ishikawa, Kenji; Hiramatsu, Mineo; Sekine, Makoto; Hori, Masaru

    2014-04-01

    Cauliflorous nanographene sheets were hierarchically regrown on the spearlike structures of carbon nanowalls (CNWs) produced by O2-plasma etching. The spears on the CNWs acted as a stem for the growth of flowerlike flaky nanographene sheets, where the root of the nanoflower was located at a defect or disordered site. The defects on the graphitic structures were induced by irradiation with oxygen-related radicals and ions in the O2-based plasmas and acted as sites for the nucleation of flowerlike nanographene. The porous carbon nanostructures regrown after O2-plasma treatment have a relatively higher surface area and are thus promising materials for electrochemical applications.

  3. Non-thermal Plasma Induces Apoptosis in Melanoma Cells via Production of Intracellular Reactive Oxygen Species

    PubMed Central

    Sensenig, Rachel; Kalghatgi, Sameer; Cerchar, Ekaterina; Fridman, Gregory; Shereshevsky, Alexey; Torabi, Behzad; Arjunan, Krishna Priya; Podolsky, Erica; Fridman, Alexander; Friedman, Gary; Azizkhan-Clifford, Jane; Brooks, Ari D.

    2012-01-01

    Non-thermal atmospheric pressure dielectric barrier discharge (DBD) plasma may provide a novel approach to treat malignancies via induction of apoptosis. The purpose of this study was to evaluate the potential of DBD plasma to induce apoptosis in melanoma cells. Melanoma cells were exposed to plasma at doses that did not induce necrosis, and cell viability and apoptotic activity were evaluated by Trypan blue exclusion test, Annexin-V/PI staining, caspase-3 cleavage, and TUNEL® analysis. Trypan blue staining revealed that non-thermal plasma treatment significantly decreased the viability of cells in a dose-dependent manner 3 and 24 h after plasma treatment. Annexin-V/PI staining revealed a significant increase in apoptosis in plasma-treated cells at 24, 48, and 72 h post-treatment (p<0.001). Caspase-3 cleavage was observed 48 h post-plasma treatment at a dose of 15 J/cm2. TUNEL® analysis of plasma-treated cells demonstrated an increase in apoptosis at 48 and 72 h post-treatment (p<0.001) at a dose of 15 J/cm2. Pre-treatment with N-acetyl-L-cysteine (NAC), an intracellular reactive oxygen species (ROS) scavenger, significantly decreased apoptosis in plasma-treated cells at 5 and 15 J/cm2. Plasma treatment induces apoptosis in melanoma cells through a pathway that appears to be dependent on production of intracellular ROS. DBD plasma production of intracellular ROS leads to dose-dependent DNA damage in melanoma cells, detected by γ-H2AX, which was completely abrogated by pre-treating cells with ROS scavenger, NAC. Plasma-induced DNA damage in turn may lead to the observed plasma-induced apoptosis. Since plasma is non-thermal, it may be used to selectively treat malignancies. PMID:21046465

  4. Surface Modification of Polypropylene Membrane by RF Methane/Oxygen Mixture Plasma Treatment

    NASA Astrophysics Data System (ADS)

    Tsai, Ching-Yuan; Juang, Ruey-Shin; Huang, Chun

    2011-08-01

    The hydrophilic surface modification of micro-porous polypropylene (PP) membranes is achieved by low-pressure 13.56 MHz RF methane (CH4)/oxygen (O2) gas mixture plasma treatment. The changes in surface wettability and surface free energy were examined by static contact angle analysis. The static water contact angle of the plasma modified membrane notably decreased with increases in treatment time and plasma power. The obvious increase in the surface energy of polypropylene membranes due to CH4/O2 mixture gas plasma treatments was also observed. Optical emission spectroscopy (OES) was used to analyze the chemical species of CH4/O2 mixture gas plasma treatment. The variations in the surface morphology and chemical structure of the micro-porous PP membranes were confirmed by confocal laser scanning microscopy (CLSM), Fourier transform infrared spectroscopy (FTIR), and X-ray photoelectron spectroscopy (XPS) measurements. XPS analysis showed significantly higher surface concentrations of oxygen functional groups for CH4/O2 mixture gas plasma-modified polypropylene membrane surfaces than for the originally unmodified polypropylene membrane surface. The experimental results show the important role of chemical species in the interaction between a CH4/O2 mixture gas plasma and a membrane surface, which can be controlled by surface modification to tailor the hydrophilicity of the membrane to the requirements of various applications.

  5. MICROPLATE-BASED OXYGEN RADICAL ABSORBANCE CAPACITY (ORAC) ASSAY OF HYDROPHILIC AND LIPOPHILIC COMPARTMENTS IN PLASMA

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Methods have been developed to evaluate the total antioxidant capacity of foods and plasma but limitations are associated with their ability to determine precisely the contribution of lipophilic antioxidants in a lipid milieu as well as interactions among them. Thus, we modified the Oxygen Radical ...

  6. Processing lunar soils for oxygen and other materials

    NASA Technical Reports Server (NTRS)

    Knudsen, Christian W.; Gibson, Michael A.

    1992-01-01

    Two types of lunar materials are excellent candidates for lunar oxygen production: ilmenite and silicates such as anorthite. Both are lunar surface minable, occurring in soils, breccias, and basalts. Because silicates are considerably more abundant than ilmenite, they may be preferred as source materials. Depending on the processing method chosen for oxygen production and the feedstock material, various useful metals and bulk materials can be produced as byproducts. Available processing techniques include hydrogen reduction of ilmenite and electrochemical and chemical reductions of silicates. Processes in these categories are generally in preliminary development stages and need significant research and development support to carry them to practical deployment, particularly as a lunar-based operation. The goal of beginning lunar processing operations by 2010 requires that planning and research and development emphasize the simplest processing schemes. However, more complex schemes that now appear to present difficult technical challenges may offer more valuable metal byproducts later. While they require more time and effort to perfect, the more complex or difficult schemes may provide important processing and product improvements with which to extend and elaborate the initial lunar processing facilities. A balanced R&D program should take this into account. The following topics are discussed: (1) ilmenite--semi-continuous process; (2) ilmenite--continuous fluid-bed reduction; (3) utilization of spent ilmenite to produce bulk materials; (4) silicates--electrochemical reduction; and (5) silicates--chemical reduction.

  7. Operational stability in pentacene thin-film transistors with threshold voltages tuned by oxygen plasma treatment

    NASA Astrophysics Data System (ADS)

    Kimura, Yoshinari; Kitamura, Masatoshi; Kitani, Asahi; Arakawa, Yasuhiko

    2016-02-01

    Pentacene-based organic thin-film transistors (TFTs) having a SiO2 gate dielectric treated with oxygen plasma have been investigated for control of the threshold voltage. The threshold voltage changed in the wide range from -15 to 80 V, depending on plasma treatment time, AC power for plasma generation, and gate dielectric thickness. The threshold voltage change was attributed to negative charges induced on and/or near the surface of the gate dielectric. The threshold voltage change on the order of 1 V was particularly proportional to plasma treatment time. The predictable change enables the control of threshold voltage in this range. In addition, the effect of gate bias stress on threshold voltage was examined. The results suggested that gate bias stress does not negate the threshold voltage change induced by plasma treatment.

  8. An atmospheric-pressure cold plasma leads to apoptosis in Saccharomyces cerevisiae by accumulating intracellular reactive oxygen species and calcium

    NASA Astrophysics Data System (ADS)

    Ma, R. N.; Feng, H. Q.; Liang, Y. D.; Zhang, Q.; Tian, Y.; Su, B.; Zhang, J.; Fang, J.

    2013-07-01

    A non-thermal plasma is known to induce apoptosis of various cells but the mechanism is not yet clear. A eukaryotic model organism Saccharomyces cerevisiaewas used to investigate the cellular and biochemical regulations of cell apoptosis and cell cycle after an atmospheric-pressure cold plasma treatment. More importantly, intracellular calcium (Ca2+) was first involved in monitoring the process of plasma-induced apoptosis in this study. We analysed the cell apoptosis and cell cycle by flow cytometry and observed the changes in intracellular reactive oxygen species (ROS) and Ca2+ concentration, cell mitochondrial membrane potential (Δψm) as well as nuclear DNA morphology via fluorescence staining assay. All experimental results indicated that plasma-generated ROS leads to the accumulation of intracellular ROS and Ca2+ that ultimately contribute to apoptosis associated with cell cycle arrest at G1 phase through depolarization of Δψm and fragmenting nuclear DNA. This work provides a novel insight into the physical and biological mechanism of apoptosis induced by a plasma which could benefit for promoting the development of plasmas applied to cancer therapy.

  9. Oxygen plasma immersion ion implantation treatment to enhance data retention of tungsten nanocrystal nonvolatile memory

    SciTech Connect

    Wang, Jer-Chyi Chang, Wei-Cheng; Lai, Chao-Sung; Chang, Li-Chun; Ai, Chi-Fong; Tsai, Wen-Fa

    2014-03-15

    Data retention characteristics of tungsten nanocrystal (W-NC) memory devices using an oxygen plasma immersion ion implantation (PIII) treatment are investigated. With an increase of oxygen PIII bias voltage and treatment time, the capacitance–voltage hysteresis memory window is increased but the data retention characteristics become degraded. High-resolution transmission electron microscopy images show that this poor data retention is a result of plasma damage on the tunneling oxide layer, which can be prevented by lowering the bias voltage to 7 kV. In addition, by using the elevated temperature retention measurement technique, the effective charge trapping level of the WO{sub 3} film surrounding the W-NCs can be extracted. This measurement reveals that a higher oxygen PIII bias voltage and treatment time induces more shallow traps within the WO{sub 3} film, degrading the retention behavior of the W-NC memory.

  10. Effects of oxygen plasma etching on Sb2Te3 explored by torque detected quantum oscillations

    NASA Astrophysics Data System (ADS)

    Yan, Yuan; Heintze, Eric; Pracht, Uwe S.; Blankenhorn, Marian; Dressel, Martin

    2016-04-01

    De Haas-van Alphen measurements evidence that oxygen plasma etching strongly affects the properties of the three-dimensional topological insulator Sb2Te3. The quantum oscillations in magnetization down to low temperature (T ≥ 2 K) and high magnetic field (B ≤ 7 T) have been systematically investigated using a high-sensitive cantilever torque magnetometer. The effective mass and the oscillation frequency obtained from de Haas-van Alphen measurements first increase and then decrease as the oxygen plasma etching time increases from 0 to 12 min, corresponding to an up- and down-shift of the Dirac point. We establish the cantilever torque magnetometer as a powerful contactless tool to investigate the oxygen sensitivity of the surface state in topological insulators.

  11. Ground-Based Tests of Spacecraft Polymeric Materials under OXY-GEN Plasma-Beam

    NASA Astrophysics Data System (ADS)

    Chernik, Vladimir; Novikov, Lev; Gaidar, Anna

    2016-07-01

    Spacecraft LEO mission is accompanied by destruction of polymeric material surface under influence of atomic oxygen flow. Sources of molecular, plasma and ion beams are used for the accelerated ground-based tests of spacecraft materials. In the work application of oxygen plasma accelerator of a duoplasmatron type is described. Plasma particles have been accelerated up to average speed of 13-16 km/s. Influence of such beam on materials leads to more intensive destruction of polymers than in LEO. This fact allows to execute tests in the accelerated time scale by a method of an effective fluence. Special measures were given to decrease a concentration of both gaseous and electrode material impurities in the oxygen beam. In the work the results of simulative tests of spacecraft materials and experiments on LEO are considered. Comparison of plasma beam simulation with LEO data has shown conformity for structures of a number of polymeric materials. The relative erosion yields (normalized with respect to polyimide) of the tested materials are shown practically equal to those in LEO. The obtained results give grounds for using the plasma-generation mode with ion energies of 20-30 eV to accelerated testing of spacecraft materials for long -term LEO missions.

  12. A New Mid-UV Resist With Oxygen Plasma Resistance

    NASA Astrophysics Data System (ADS)

    Liu, J. M.; Tzeng, Chao Huei

    1989-08-01

    A new silyl ether of resorcinol novolak resin (SERN) and a new photoactive compound (S-55NQ) have been developed for a bilayer resist system. The SERN resin is an addition-condensation type terpolymer from resorcinol, hexamethylenetetramine, and phenyl silyl ether (PSE), which is a reaction product of resorcinol and chlorosilane, under acid catalyzed condition. The S-55NQ sensitizer is a sulfonate ester of spiroglycol and naphthoquinone diazide. This alkaline soluble Si-containing resist, useful in the mid-UV region, shows high dry etching resistance to O2 plasma and O2 RIE. An etching rate ratio of 4.5 or higher based on HPR-204 as the bottom layer is obtained.

  13. The Variable Polarity Plasma Arc Welding Process: Its Application to the Space Shuttle External Tank

    NASA Technical Reports Server (NTRS)

    Nunes, A. C., Jr.; Bayless, E. O., Jr.; Wilson, W. A.

    1984-01-01

    This report describes progress in the implementation of the Variable Polarity Plasma Arc Welding (VPPAW) process at the External Tank (ET) assembly facility. Design allowable data has been developed for thicknesses up to 1.00 in. More than 24,000 in. of welding on liquid oxygen and liquid hydrogen cylinders has been made without an internal defect.

  14. Oxygen isotopic signature of CO2 from combustion processes

    NASA Astrophysics Data System (ADS)

    Schumacher, M.; Neubert, R. E. M.; Meijer, H. A. J.; Jansen, H. G.; Brand, W. A.; Geilmann, H.; Werner, R. A.

    2008-11-01

    For a comprehensive understanding of the global carbon cycle precise knowledge of all processes is necessary. Stable isotope (13C and 18O) abundances provide information for the qualification and the quantification of the diverse source and sink processes. This study focuses on the δ18O signature of CO2 from combustion processes, which are widely present both naturally (wild fires), and human induced (fossil fuel combustion, biomass burning) in the carbon cycle. All these combustion processes use atmospheric oxygen, of which the isotopic signature is assumed to be constant with time throughout the whole atmosphere. The combustion is generally presumed to take place at high temperatures, thus minimizing isotopic fractionation. Therefore it is generally supposed that the 18O signature of the produced CO2 is equal to that of the atmospheric oxygen. This study, however, reveals that the situation is much more complicated and that important fractionation effects do occur. From laboratory studies fractionation effects in the order of about 26‰ became obvious, a clear differentiation of about 7‰ was also found in car exhausts which were sampled directly under ambient atmospheric conditions. We investigated a wide range of materials (both different raw materials and similar materials with different inherent 18O signature), sample geometries (e.g. texture and surface-volume ratios) and combustion circumstances. We found that the main factor influencing the specific isotopic signatures of the combustion-derived CO2 and of the concomitantly released oxygen-containing side products, is the case-specific rate of combustion. This points firmly into the direction of (diffusive) transport of oxygen to the reaction zone as the cause of the isotope fractionation. The original 18O signature of the material appeared to have little or no influence.

  15. Oxygen isotopic signature of CO2 from combustion processes

    NASA Astrophysics Data System (ADS)

    Schumacher, M.; Werner, R. A.; Meijer, H. A. J.; Jansen, H. G.; Brand, W. A.; Geilmann, H.; Neubert, R. E. M.

    2011-02-01

    For a comprehensive understanding of the global carbon cycle precise knowledge of all processes is necessary. Stable isotope (13C and 18O) abundances provide information for the qualification and the quantification of the diverse source and sink processes. This study focuses on the δ18O signature of CO2 from combustion processes, which are widely present both naturally (wild fires), and human induced (fossil fuel combustion, biomass burning) in the carbon cycle. All these combustion processes use atmospheric oxygen, of which the isotopic signature is assumed to be constant with time throughout the whole atmosphere. The combustion is generally presumed to take place at high temperatures, thus minimizing isotopic fractionation. Therefore it is generally supposed that the 18O signature of the produced CO2 is equal to that of the atmospheric oxygen. This study, however, reveals that the situation is much more complicated and that important fractionation effects do occur. From laboratory studies fractionation effects on the order of up to 26%permil; became obvious in the derived CO2 from combustion of different kinds of material, a clear differentiation of about 7‰ was also found in car exhausts which were sampled directly under ambient atmospheric conditions. We investigated a wide range of materials (both different raw materials and similar materials with different inherent 18O signature), sample geometries (e.g. texture and surface-volume ratios) and combustion circumstances. We found that the main factor influencing the specific isotopic signatures of the combustion-derived CO2 and of the concomitantly released oxygen-containing side products, is the case-specific rate of combustion. This points firmly into the direction of (diffusive) transport of oxygen to the reaction zone as the cause of the isotope fractionation. The original total 18O signature of the material appeared to have little influence, however, a contribution of specific bio-chemical compounds to

  16. A Fiber Optic Catalytic Sensor for Neutral Atom Measurements in Oxygen Plasma

    PubMed Central

    Zaplotnik, Rok; Vesel, Alenka; Mozetic, Miran

    2012-01-01

    The presented sensor for neutral oxygen atom measurement in oxygen plasma is a catalytic probe which uses fiber optics and infrared detection system to measure the gray body radiation of the catalyst. The density of neutral atoms can be determined from the temperature curve of the probe, because the catalyst is heated predominantly by the dissipation of energy caused by the heterogeneous surface recombination of neutral atoms. The advantages of this sensor are that it is simple, reliable, easy to use, noninvasive, quantitative and can be used in plasma discharge regions. By using different catalyst materials the sensor can also be applied for detection of neutral atoms in other plasmas. Sensor design, operation, example measurements and new measurement procedure for systematic characterization are presented. PMID:22666005

  17. A Comparison of Atomic Oxygen Degradation in Low Earth Orbit and in a Plasma Etcher

    NASA Technical Reports Server (NTRS)

    Townsend, Jacqueline A.; Park, Gloria

    1997-01-01

    In low Earth orbit (LEO) significant degradation of certain materials occurs from exposure to atomic oxygen (AO). Orbital opportunities to study this degradation for specific materials are limited and expensive. While plasma etchers are commonly used in ground-based studies because of their low cost and convenience, the environment produced in an etcher chamber differs greatly from the LEO environment. Because of the differences in environment, the validity of using etcher data has remained an open question. In this paper, degradation data for 22 materials from the orbital experiment Evaluation of Oxygen Interaction with Materials (EOIM-3) are compared with data from EOIM-3 control specimens exposed in a typical plasma etcher. This comparison indicates that, when carefully considered, plasma etcher results can produce order-of-magnitude estimates of orbital degradation. This allows the etcher to be used to screen unacceptable materials from further, more expensive tests.

  18. Characteristics of ITO films with oxygen plasma treatment for thin film solar cell applications

    SciTech Connect

    Park, Yong Seob; Kim, Eungkwon; Hong, Byungyou; Lee, Jaehyoeng

    2013-12-15

    Graphical abstract: The effect of O{sub 2} plasma treatment on the surface and the work function of ITO films. - Highlights: • ITO films were prepared on the glass substrate by RF magnetron sputtering method. • Effects of O{sub 2} plasma treatment on the properties of ITO films were investigated. • The work function of ITO film was changed from 4.67 to 5.66 eV by plasma treatment. - Abstract: The influence of oxygen plasma treatment on the electro-optical and structural properties of indium-tin-oxide films deposited by radio frequency magnetron sputtering method were investigated. The films were exposed at different O{sub 2} plasma powers and for various durations by using the plasma enhanced chemical vapor deposition (PECVD) system. The resistivity of the ITO films was almost constant, regardless of the plasma treatment conditions. Although the optical transmittance of ITO films was little changed by the plasma power, the prolonged treatment slightly increased the transmittance. The work function of ITO film was changed from 4.67 eV to 5.66 eV at the plasma treatment conditions of 300 W and 60 min.

  19. The Role of Oxygen Partial Pressure in Controlling the Phase Composition of La1- x Sr x Co y Fe1- y O3- δ Oxygen Transport Membranes Manufactured by Means of Plasma Spray-Physical Vapor Deposition

    NASA Astrophysics Data System (ADS)

    Marcano, D.; Mauer, G.; Sohn, Y. J.; Vaßen, R.; Garcia-Fayos, J.; Serra, J. M.

    2016-04-01

    La0.58Sr0.4Co0.2Fe0.8O3 - δ (LSCF) deposited on a metallic porous support by plasma spray-physical vapor deposition is a promising candidate for oxygen-permeation membranes. Ionic transport properties are regarded to depend on the fraction of perovskite phase present in the membrane. However, during processing, the LSCF powder decomposes into perovskite and secondary phases. In order to improve the ionic transport properties of the membranes, spraying was carried out at different oxygen partial pressures p(O2). It was found that coatings deposited at lower and higher oxygen partial pressures consist of 70% cubic/26% rhombohedral and 61% cubic/35% rhombohedral perovskite phases, respectively. During annealing, the formation of non-perovskite phases is driven by oxygen non-stoichiometry. The amount of oxygen added during spraying can be used to increase the perovskite phase fraction and suppress the formation of non-perovskite phases.

  20. Redox Processes in Neurodegenerative Disease Involving Reactive Oxygen Species

    PubMed Central

    Kovacic, Peter; Somanathan, Ratnasamy

    2012-01-01

    Much attention has been devoted to neurodegenerative diseases involving redox processes. This review comprises an update involving redox processes reported in the considerable literature in recent years. The mechanism involves reactive oxygen species and oxidative stress, usually in the brain. There are many examples including Parkinson’s, Huntington’s, Alzheimer’s, prions, Down’s syndrome, ataxia, multiple sclerosis, Creutzfeldt-Jacob disease, amyotrophic lateral sclerosis, schizophrenia, and Tardive Dyskinesia. Evidence indicates a protective role for antioxidants, which may have clinical implications. A multifaceted approach to mode of action appears reasonable. PMID:23730253

  1. Tailoring surface properties of polyethylene separator by low pressure 13.56 MHz RF oxygen plasma glow discharge

    NASA Astrophysics Data System (ADS)

    Li, Chun; Liang, Chia-Han; Huang, Chun

    2016-01-01

    Low-pressure plasma surface modification in a radio-frequency capacitively coupled glow discharge of oxygen gas was carried out to induce polar functional groups onto polyethylene membrane separator surfaces to enhance its hydrophilicity. The surface changes in surface free energy were monitored by static contact angle measurement. A significant increase in the surface energy of polyethylene membrane separators caused by the oxygen gas plasma modifications was observed. The static water contact angle of the plasma-modified membrane separator significantly decreased with the increase in treatment duration and plasma power. An obvious increase in the surface energy of the membrane separators owing to the oxidative effect of oxygen-gas-plasma modifications was also observed. Optical emission spectroscopy was carried out to analyze the chemical species generated by oxygen gas plasma surface modification. The variations in the surface morphology and chemical structure of the separators were confirmed by scanning electron microscopy, Fourier transform infrared spectroscopy, and X-ray photoelectron spectroscopy (XPS). XPS showed significantly higher surface concentrations of oxygen functional groups in the oxygen-gas-plasma-modified polymeric separator surfaces than in the unmodified polymeric separator surface. The experimental results show the important role of chemical species in the interaction between oxygen gas plasmas and the separator surface, which can be controlled by surface modification to tailor the hydrophilicity of the separator.

  2. Offgas emissions from the plasma hearth process

    SciTech Connect

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

    1996-12-31

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

  3. Ozone-stimulated emission due to atomic oxygen population inversions in an argon microwave plasma torch

    SciTech Connect

    Lukina, N. A.; Sergeichev, K. F.

    2008-06-15

    It is shown that, in a microwave torch discharge in an argon jet injected into an oxygen atmosphere at normal pressure, quasi-resonant energy transfer from metastable argon atoms to molecules of oxygen and ozone generated in the torch shell and, then, to oxygen atoms produced via the dissociation of molecular oxygen and ozone leads to the inverse population of metastable levels of atomic oxygen. As a result, the excited atomic oxygen with population inversions becomes a gain medium for lasing at wavelengths of 844.6 and 777.3 nm (the 3{sup 3}P-3{sup 3}S and 3{sup 5}P-3{sup 5}S transitions). It is shown that an increase in the ozone density is accompanied by an increase in both the lasing efficiency at these wavelength and the emission intensity of the plasma-forming argon at a wavelength of 811.15 nm (the {sup 2}P{sup 0}4s-{sup 2}P{sup 0}4p transition). When the torch operates unstably, the production of singlet oxygen suppresses ozone generation; as a result, the lasing effect at these wavelengths disappears.

  4. Reactive oxygen species in development and infection processes.

    PubMed

    Marschall, Robert; Tudzynski, Paul

    2016-09-01

    Reactive oxygen species (ROS) are important signaling molecules that affect vegetative and pathogenic processes in pathogenic fungi. There is growing evidence that ROS are not only secreted during the interaction of host and pathogen but also involved in tightly controlled intracellular processes. The major ROS producing enzymes are NADPH oxidases (Nox). Recent investigations in fungi revealed that Nox-activity is responsible for the formation of infection structures, cytoskeleton architecture as well as interhyphal communication. However, information about the localization and site of action of the Nox complexes in fungi is limited and signaling pathways and intracellular processes affected by ROS have not been fully elucidated. This review focuses on the role of ROS as signaling molecules in fungal "model" organisms: it examines the role of ROS in vegetative and pathogenic processes and gives special attention to Nox complexes and their function as important signaling hubs. PMID:27039026

  5. ESCA study of Kapton exposed to atomic oxygen in low earth orbit or downstream from a radio-frequency oxygen plasma

    NASA Technical Reports Server (NTRS)

    Golub, Morton A.; Wydeven, Theodore; Cormia, Robert D.

    1988-01-01

    The ESCA spectra of Kapton polyimide film exposed to atomic oxygen O(3P), either in low earth orbit (LEO) on the STS-8 Space Shuttle or downstream from a radio-frequency oxygen plasma, were compared. The major difference in surface chemistry induced by the two types of exposure to O(3P), both of which caused surface recession (etching), was a much larger uptake of oxygen by Kapton etched in the O2 plasma than in LEO. This difference is attributed to the presence of molecular oxygen in the plasma reactor and its absence in LEO: in the former case, O2 can react with radicals generated in the Kapton molecule as it etches, become incorporated in the etched polymer, and thereby yield a higher steady-state 'surface oxidation' level than in LEO.

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

    SciTech Connect

    Forest, Cary B.

    2013-09-19

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

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

    SciTech Connect

    Vitelaru, Catalin; Lundin, Daniel; Brenning, Nils; Minea, Tiberiu

    2013-09-02

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

  8. Phase diagram of carbon-oxygen plasma mixtures in white dwarf stars

    NASA Astrophysics Data System (ADS)

    Schneider, A. S.; Horowitz, C. J.; Hughto, J.; Berry, D. K.

    2012-12-01

    The liquid-solid phase-diagram of dense carbon-oxygen plasma mixtures found in white dwarf stars interiors is determined from molecular dynamics (MD) simulations. Our MD simulations consist of boxes with 55296 ions with different carbon to oxygen ratios. Finite size effects are estimated comparing the new MD simulations results to previous smaller simulations. We use bond angle metric to identify whether an ion is in the solid, liquid or interface and study non-equilibrium effects by obtaining the diffusion coefficients in the different phases. Our phase diagram agrees with predictions from Medin and Cumming obtained by an independent method.

  9. Comprehensive computational model for thermal plasma processing

    NASA Astrophysics Data System (ADS)

    Chang, C. H.

    A new numerical model is described for simulating thermal plasmas containing entrained particles, with emphasis on plasma spraying applications. The plasma is represented as a continuum multicomponent chemically reacting ideal gas, while the particles are tracked as discrete Lagrangian entities coupled to the plasma. The overall computational model is embodied in a new computer code called LAVA. Computational results are presented from a transient simulation of alumina spraying in a turbulent argon-helium plasma jet in air environment, including torch geometry, substrate, and multiple species with chemical reactions. Plasma-particle interactions including turbulent dispersion have been modeled in a fully self-consistent manner.

  10. Effect of additive oxygen gas on cellular response of lung cancer cells induced by atmospheric pressure helium plasma jet.

    PubMed

    Joh, Hea Min; Choi, Ji Ye; Kim, Sun Ja; Chung, T H; Kang, Tae-Hong

    2014-01-01

    The atmospheric pressure helium plasma jet driven by pulsed dc voltage was utilized to treat human lung cancer cells in vitro. The properties of plasma plume were adjusted by the injection type and flow rate of additive oxygen gas in atmospheric pressure helium plasma jet. The plasma characteristics such as plume length, electric current and optical emission spectra (OES) were measured at different flow rates of additive oxygen to helium. The plasma plume length and total current decreased with an increase in the additive oxygen flow rate. The electron excitation temperature estimated by the Boltzmann plot from several excited helium emission lines increased slightly with the additive oxygen flow. The oxygen atom density in the gas phase estimated by actinometry utilizing argon was observed to increase with the additive oxygen flow. The concentration of intracellular reactive oxygen species (ROS) measured by fluorescence assay was found to be not exactly proportional to that of extracellular ROS (measured by OES), but both correlated considerably. It was also observed that the expression levels of p53 and the phospho-p53 were enhanced in the presence of additive oxygen flow compared with those from the pure helium plasma treatment. PMID:25319447

  11. Effect of additive oxygen gas on cellular response of lung cancer cells induced by atmospheric pressure helium plasma jet

    NASA Astrophysics Data System (ADS)

    Joh, Hea Min; Choi, Ji Ye; Kim, Sun Ja; Chung, T. H.; Kang, Tae-Hong

    2014-10-01

    The atmospheric pressure helium plasma jet driven by pulsed dc voltage was utilized to treat human lung cancer cells in vitro. The properties of plasma plume were adjusted by the injection type and flow rate of additive oxygen gas in atmospheric pressure helium plasma jet. The plasma characteristics such as plume length, electric current and optical emission spectra (OES) were measured at different flow rates of additive oxygen to helium. The plasma plume length and total current decreased with an increase in the additive oxygen flow rate. The electron excitation temperature estimated by the Boltzmann plot from several excited helium emission lines increased slightly with the additive oxygen flow. The oxygen atom density in the gas phase estimated by actinometry utilizing argon was observed to increase with the additive oxygen flow. The concentration of intracellular reactive oxygen species (ROS) measured by fluorescence assay was found to be not exactly proportional to that of extracellular ROS (measured by OES), but both correlated considerably. It was also observed that the expression levels of p53 and the phospho-p53 were enhanced in the presence of additive oxygen flow compared with those from the pure helium plasma treatment.

  12. Effect of additive oxygen gas on cellular response of lung cancer cells induced by atmospheric pressure helium plasma jet

    PubMed Central

    Joh, Hea Min; Choi, Ji Ye; Kim, Sun Ja; Chung, T. H.; Kang, Tae-Hong

    2014-01-01

    The atmospheric pressure helium plasma jet driven by pulsed dc voltage was utilized to treat human lung cancer cells in vitro. The properties of plasma plume were adjusted by the injection type and flow rate of additive oxygen gas in atmospheric pressure helium plasma jet. The plasma characteristics such as plume length, electric current and optical emission spectra (OES) were measured at different flow rates of additive oxygen to helium. The plasma plume length and total current decreased with an increase in the additive oxygen flow rate. The electron excitation temperature estimated by the Boltzmann plot from several excited helium emission lines increased slightly with the additive oxygen flow. The oxygen atom density in the gas phase estimated by actinometry utilizing argon was observed to increase with the additive oxygen flow. The concentration of intracellular reactive oxygen species (ROS) measured by fluorescence assay was found to be not exactly proportional to that of extracellular ROS (measured by OES), but both correlated considerably. It was also observed that the expression levels of p53 and the phospho-p53 were enhanced in the presence of additive oxygen flow compared with those from the pure helium plasma treatment. PMID:25319447

  13. Observation of inactivation of Bacillus sbtilis spores under exposures of oxygen added argon atmospheric pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Shen, Jie; Cheng, Cheng; Zhao, Ying; Xiao, Dezhi; Lan, Yan; Xie, Hongbing; Cheng, Junli; Meng, Yuedong; Li, Jiangang; Chu, Paul K.

    2014-11-01

    The inactivation of Bacillus subtilis spores by an Ar plasma jet mixed with different amounts of oxygen is reported. 5.8 × 106 B. subtilis spores are sterilized by an Ar/O2 (8.7%) plasma jet after exposure for 2 min. The densities of ozone and oxygen radicals in the Ar/O2 plasma jet increase with oxygen concentration and are estimated by optical spectroscopy diagnostic. The malondialdehyde (MDA) test shows that oxygen radicals participate in bacterial inactivation. Scanning electron microscopy (SEM) reveals the deformation of the spore shape due to etching by oxygen radicals and the dependence of the degree of deformation on the density of oxygen radicals.

  14. Plasma Discharge Process in a Pulsed Diaphragm Discharge System

    NASA Astrophysics Data System (ADS)

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

    2014-12-01

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

  15. Cleaning of diamond nanoindentation probes with oxygen plasma and carbon dioxide snow

    SciTech Connect

    Morris, Dylan J.

    2009-12-15

    Diamond nanoindentation probes may perform thousands of indentations over years of service life. There is a broad agreement that the probes need frequent cleaning, but techniques for doing so are mostly anecdotes shared between experimentalists. In preparation for the measurement of the shape of a nanoindentation probe by a scanning probe microscope, cleaning by carbon dioxide snow jets and oxygen plasma was investigated. Repeated indentation on a thumbprint-contaminated surface formed a compound that was very resistant to removal by solvents, CO{sub 2} snow, and plasma. CO{sub 2} snow cleaning is found to be a generally effective cleaning procedure.

  16. Oxygen transport through polyethylene terephthalate (PET) coated with plasma-polymerized acetylene at atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Wemlinger, Erik; Pedrow, Patrick; Garcia-Pérez, Manuel; Sablani, Shyam

    2011-10-01

    Moser et al. have shown that oxygen transport through polyethyleneterephthalate (PET) is reduced by a factor of up to 120 when, at reduced pressure, hydrogenated amorphous carbon film with thickness less than 100 nm is applied to the PET substrate. Our work includes using atmospheric pressure cold plasma to grow a plasma-polymerized acetylene film on PET substrate and measuring reductions in oxygen transport. The reactor utilizes corona discharges and is operated at 60 Hz with a maximum voltage of 10 kV RMS. Corona streamers emanate from an array of needles with an average radius of curvature of 50 μm. The reactor utilizes a cylindrical reaction chamber with a vertical orientation such that argon carrier gas and acetylene precursor gas are introduced at the top then pass through the cold plasma activation zone and then through a grounded stainless steel mesh. Acetylene radicals are incident on the PET substrate and form plasma-polymerized acetylene film. Moser et al. have shown that oxygen transport through polyethyleneterephthalate (PET) is reduced by a factor of up to 120 when, at reduced pressure, hydrogenated amorphous carbon film with thickness less than 100 nm is applied to the PET substrate. Our work includes using atmospheric pressure cold plasma to grow a plasma-polymerized acetylene film on PET substrate and measuring reductions in oxygen transport. The reactor utilizes corona discharges and is operated at 60 Hz with a maximum voltage of 10 kV RMS. Corona streamers emanate from an array of needles with an average radius of curvature of 50 μm. The reactor utilizes a cylindrical reaction chamber with a vertical orientation such that argon carrier gas and acetylene precursor gas are introduced at the top then pass through the cold plasma activation zone and then through a grounded stainless steel mesh. Acetylene radicals are incident on the PET substrate and form plasma-polymerized acetylene film. E.M. Moser, R. Urech, E. Hack, H. Künzli, E. Müller, Thin

  17. Physical processes associated with current collection by plasma contactors

    NASA Technical Reports Server (NTRS)

    Katz, Ira; Davis, Victoria A.

    1990-01-01

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

  18. Lagrangian coherent structures and plasma transport processes

    NASA Astrophysics Data System (ADS)

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

    2015-10-01

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

  19. Laser Diagnostics of Atomic Hydrogen and Oxygen Production in RF and Microwave Plasma Discharges

    NASA Astrophysics Data System (ADS)

    Preppernau, Bryan Lee

    1993-01-01

    The research for this thesis involved the application of two-photon allowed laser-induced fluorescence (TALIF) to the study of atomic hydrogen and oxygen production in industrial scale radio-frequency and microwave plasma discharge apparatus. Absolute atomic hydrogen concentration profiles were measured in a Gaseous Electronics Conference Reference Cell installed at Wright-Patterson AFB, Ohio operating with a simple H_2 discharge. Two -dimensional atomic hydrogen concentration profiles were also measured in an ASTEX HPMM microwave plasma diamond deposition reactor during actual diamond growth. In addition, absolute atomic oxygen concentrations were measured in the ASTEX system. Particular attention was paid to refining the concentration calibration technique and in determining a correction to account for the collisional quenching of excited state fluorescence in high pressure gases.

  20. Oxygen plasma flow properties deduced from laser-induced fluorescence and probe measurements.

    PubMed

    Löhle, Stefan; Eichhorn, Christoph; Steinbeck, Andreas; Lein, Sebastian; Herdrich, Georg; Röser, Hans-Peter; Auweter-Kurtz, Monika

    2008-04-10

    Estimation of the local dissociation degree and the local mass-specific enthalpy of a pure oxygen plasma flow determined mainly from laser-induced fluorescence measurements are reported. Measurements have been conducted for several generator parameters in an inductively heated plasma wind tunnel. Additional probe measurements of total pressure together with the deduced translational temperature are used to estimate the local mass-specific enthalpy. For a reference condition, full dissociation has been measured. The measured translational temperature of atomic oxygen for this condition is T = 3500 K. Subsequently, the local mass-specific enthalpy has been derived using these local density and temperature measurements. For the reference condition the estimated value of h = 27 MJ/kg is in good agreement with the probe measurements and results from diode laser absorption spectroscopy. PMID:18404183

  1. Oxygen Plasma Modification of Poss-Coated Kapton(Registered TradeMark) HN Films

    NASA Technical Reports Server (NTRS)

    Wohl, C. J.; Belcher, M. A.; Ghose, S.; Connell, J. W.

    2008-01-01

    The surface energy of a material depends on both surface composition and topographic features. In an effort to modify the surface topography of Kapton(Registered TradeMark) HN film, organic solutions of a polyhedral oligomeric silsesquioxane, octakis(dimethylsilyloxy)silsesquioxane (POSS), were spray-coated onto the Kapton(Registered TradeMark) HN surface. Prior to POSS application, the Kapton(Registered TradeMark) HN film was activated by exposure to radio frequency (RF)-generated oxygen plasma. After POSS deposition and solvent evaporation, the films were exposed to various durations of RF-generated oxygen plasma to create a topographically rich surface. The modified films were characterized using optical microscopy, attenuated total reflection infrared (ATR-IR) spectroscopy, and high-resolution scanning electron microscopy (HRSEM). The physical properties of the modified films will be presented.

  2. Photooxidation of plasma polymerized polydimethylsiloxane film by 172 nm vacuum ultraviolet light irradiation in dilute oxygen

    NASA Astrophysics Data System (ADS)

    Ichikawa, S.

    2006-08-01

    Plasma polymerized polydimethylsiloxane films irradiated under different partial pressures of oxygen with a 172nm vacuum ultraviolet light were investigated in order to clarify the roles of molecular oxygen and photons in photooxidation. The thickness, densities, surface roughness, elemental compositions, and molecular structures of the irradiated and unirradiated films were examined by using glazing incidence x-ray reflectivity, Rutherford backscattering, infrared, and x-ray absorption (XAS) spectroscopies. Photooxidation is hardly promoted by irradiation in a high vacuum of 1×10-4Pa, though photodesorption of the methyl group and formation of Si-H bonds were observed. Silica films thicker than 140nm were formed at room temperature by irradiating them in low pressure oxygen gases. The degree of oxidation was smaller for the oxygen pressure of 10kPa than for 83Pa. Si K-edge XAS was performed to clarify the change of coordination environment of silicon by photooxidation in dilute oxygen flow containing less than 5ppm of molecular oxygen.

  3. Method and apparatus for monitoring plasma processing operations

    DOEpatents

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

    2001-01-01

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

  4. Method and apparatus for monitoring plasma processing operations

    DOEpatents

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

    2000-01-01

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

  5. Method and apparatus for monitoring plasma processing operations

    DOEpatents

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

    2001-01-01

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

  6. Method and apparatus for monitoring plasma processing operations

    DOEpatents

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

    2002-07-16

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

  7. Roles of plasma-generated vacuum-ultraviolet photons and oxygen radicals in damaging nanoporous low-k films

    SciTech Connect

    Lee, Joe; Graves, David B.

    2013-07-15

    One important class of low-k materials used as interconnect dielectrics employs methyl groups added to nanoporous SiO{sub 2} matrices. These carbon-doped oxide materials are known to be susceptible to damage from plasma species during various stages of plasma processing. Two key active species generated in O{sub 2} plasma are oxygen (O) radicals and vacuum-ultraviolet (VUV) photons. These species are known to cause carbon loss, resulting in damaging increases in dielectric constant throughout the film. However, the mechanisms through which this damage is incurred are poorly understood. By capping the substrate in different ways during plasma exposure, it is possible to expose films to either photons alone or O atoms alone. The authors report measurements of damage induced by VUV photons only, O radicals only, and the combination of O radicals and photons. Through HF stripping, they note that carbon extraction from photons and from radicals yields different outcomes; the profile of carbon concentration within the modified region is different for each case. Damage from photons alone can be modeled and model predictions are in good agreement with measurements. Damage from O atoms alone can only be modeled if it is assumed that the near-surface region has a significantly reduced diffusivity compared to the bulk of the film. Experiment and model agree that both photons alone and O radicals alone damage the material by removing carbon. When radicals and photons are present simultaneously during plasma exposure, however, more C removal appears to be occurring in the model than experimentally observed. Remarkably, if only radicals are exposed to the film after short (10-30 s) plasma exposures, very little additional damage is incurred during this radical-only exposure. The most straightforward interpretation of these results appears to be that photons combine synergistically with radicals in the pores to narrow the pores, thereby reducing film diffusivity in the C

  8. A ground-based radio frequency inductively coupled plasma apparatus for atomic oxygen simulation in low Earth orbit

    NASA Astrophysics Data System (ADS)

    Huang, Yongxian; Tian, Xiubo; Yang, Shiqin; Chu, Paul K.

    2007-10-01

    A radio frequency (rf) inductively coupled plasma apparatus has been developed to simulate the atomic oxygen environment encountered in low Earth orbit (LEO). Basing on the novel design, the apparatus can achieve stable, long lasting operation, pure and high density oxygen plasma beam. Furthermore, the effective atomic oxygen flux can be regulated. The equivalent effective atomic oxygen flux may reach (2.289-2.984)×1016at./cm2s at an oxygen pressure of 1.5Pa and rf power of 400W. The equivalent atomic oxygen flux is about 100 times than that in the LEO environment. The mass loss measured from the polyimide sample changes linearly with the exposure time, while the density of the eroded holes becomes smaller. The erosion mechanism of the polymeric materials by atomic oxygen is complex and involves initial reactions at the gas-surface interface as well as steady-state material removal.

  9. A ground-based radio frequency inductively coupled plasma apparatus for atomic oxygen simulation in low Earth orbit.

    PubMed

    Huang, Yongxian; Tian, Xiubo; Yang, Shiqin; Chu, Paul K

    2007-10-01

    A radio frequency (rf) inductively coupled plasma apparatus has been developed to simulate the atomic oxygen environment encountered in low Earth orbit (LEO). Basing on the novel design, the apparatus can achieve stable, long lasting operation, pure and high density oxygen plasma beam. Furthermore, the effective atomic oxygen flux can be regulated. The equivalent effective atomic oxygen flux may reach (2.289-2.984) x 10(16) at.cm(2) s at an oxygen pressure of 1.5 Pa and rf power of 400 W. The equivalent atomic oxygen flux is about 100 times than that in the LEO environment. The mass loss measured from the polyimide sample changes linearly with the exposure time, while the density of the eroded holes becomes smaller. The erosion mechanism of the polymeric materials by atomic oxygen is complex and involves initial reactions at the gas-surface interface as well as steady-state material removal. PMID:17979410

  10. Surface monofunctionalized polymethyl pentene hollow fiber membranes by plasma treatment and hemocompatibility modification for membrane oxygenators

    NASA Astrophysics Data System (ADS)

    Huang, Xin; Wang, Weiping; Zheng, Zhi; Fan, Wenling; Mao, Chun; Shi, Jialiang; Li, Lei

    2016-01-01

    The hemocompatibility of polymethyl pentene (PMP) hollow fiber membranes (HFMs) was improved through surface modification for membrane oxygenator applications. The modification was performed stepwise with the following: (1) oxygen plasma treatment, (2) functionalization of monosort hydroxyl groups through NaBH4 reduction, and (3) grafting 2-methacryloyloxyethyl phosphorylcholine (MPC) or heparin. SEM, ATR-FTIR, and XPS analyses were conducted to confirm successful grafting during the modification. The hemocompatibility of PMP HFMs was analyzed and compared through protein adsorption, platelet adhesion, and coagulation tests. Pure CO2 and O2 permeation rates, as well as in vitro gas exchange rates, were determined to evaluate the mass transfer properties of PMP HFMs. SEM results showed that different nanofibril topographies were introduced on the HFM surface. ATR-FTIR and XPS spectra indicated the presence of functionalization of monosort hydroxyl group and the grafting of MPC and heparin. Hemocompatibility evaluation results showed that the modified PMP HFMs presented optimal hemocompatibility compared with pristine HFMs. Gas permeation results revealed that gas permeation flux increased in the modified HFMs because of dense surface etching during the plasma treatment. The results of in vitro gas exchange rates showed that all modified PMP HFMs presented decreased gas exchange rates because of potential surface fluid wetting. The proposed strategy exhibits a potential for fabricating membrane oxygenators for biomedical applications to prevent coagulation formation and alter plasma-induced surface topology and composition.