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Sample records for plasma surface engineering

  1. Impulse Plasma In Surface Engineering - a review

    NASA Astrophysics Data System (ADS)

    Zdunek, K.; Nowakowska-Langier, K.; Chodun, R.; Okrasa, S.; Rabinski, M.; Dora, J.; Domanowski, P.; Halarowicz, J.

    2014-11-01

    The article describes the view of the plasma surface engineering, assuming the role of non-thermal energy effects in the synthesis of materials and coatings deposition. In the following study it was underlined that the vapor excitation through the application of an electric field during coatings deposition gives new possibilities for coatings formation. As an example the IPD method was chosen. During the IPD (Impulse Plasma Deposition) the impulse plasma is generated in the coaxial accelerator by strong periodic electrical pulses. The impulse plasma is distributed in the form of energetic plasma pockets. Due to the almost completely ionization of gas, the nucleation of new phases takes place on ions directly in the plasma itself. As a result the coatings of metastable materials with nano-amorphous structure and excellent adhesion to the non-heated intentionally substrates could be deposited. Recently the novel way of impulse plasma generation during the coatings deposition was proposed and developed by our group. An efficient tool for plasma process control, the plasma forming gas injection to the interelectrode space was used. Periodic changing the gas pressure results in increasing both the degree of dispersion and the dynamics of the plasma pulses. The advantage of the new technique in deposition of coatings with exceptionally good properties has been demonstrated in the industrial scale not only in the case of the IPD method but also in the case of very well known magnetron sputtering method.

  2. Trends in surface engineering of biomaterials: atmospheric pressure plasma deposition of coatings for biomedical applications

    NASA Astrophysics Data System (ADS)

    da Ponte, G.; Sardella, E.; Fanelli, F.; D'Agostino, R.; Favia, P.

    2011-11-01

    Cold plasma processes for surface engineering of biomaterials and biomedical devices are traditionally performed at low pressure; more and more, though, surface modification plasma processes at atmospheric pressure are also gaining popularity. This short review is aimed to list briefly atmospheric pressure plasma processes reported, in the last decade, for adapting the surface of materials to the best interactions with cells, bacteria and biomolecules.

  3. IPD -The Use of Impulse Plasma in Surface Engineering

    NASA Astrophysics Data System (ADS)

    Zdunek, Krzysztof

    2008-10-01

    It is evident that impulse plasma ensures both the highest level of nonequilibrity and highest level of vapour ionisation. These conditions seemed to be especially suitable for synthetizing the phases with high energetic barrier of nucleation process. In our methods, called by us as the Impulse Plasma Deposition (IPD) the impulse plasma is generated and accelerated in a coaxial accelerator. The only source of electric energy in the plasma process is condenser battery charged to the voltage of order of kVs. During the discharge of condensers individual plasmoids are being accelerated in the coaxial generator by the Ampere force to the speed of the order of 10^4 ms-1 and directed to the non-heated substrate. The most characteristic feature of the is that the synthesis proceeds in the impulse plasma itself, with the participation of ions. The crystallization on ions (ionization degree of the impulse plasma is equal to 100%) makes individual plasmoids to be strongly enriched rather in clusters or particles agglomerates with dimensions of order of single nms than the atoms. Because of the very short life time of plasmoids (approx. 10-4 sec each) the surface coalescence of particles delivered to the substrate has a limited character. As a consequence the material of the layer has nanocrystalline, globular morphology.

  4. Experimental measurements of surface damage and residual stresses in micro-engineered plasma facing materials

    NASA Astrophysics Data System (ADS)

    Rivera, David; Wirz, Richard E.; Ghoniem, Nasr M.

    2017-04-01

    The thermomechanical damage and residual stresses in plasma-facing materials operating at high heat flux are experimentally investigated. Materials with micro-surfaces are found to be more resilient, when exposed to cyclic high heat flux generated by an arc-jet plasma. An experimental facility, dedicated to High Energy Flux Testing (HEFTY), is developed for testing cyclic heat flux in excess of 10 MW/m2. We show that plastic deformation and subsequent fracture of the surface can be controlled by sample cooling. We demonstrate that W surfaces with micro-pillar type surface architecture have significantly reduced residual thermal stresses after plasma exposure, as compared to those with flat surfaces. X-ray diffraction (XRD) spectra of the W-(110) peak reveal that broadening of the Full Width at Half Maximum (FWHM) for micro-engineered samples is substantially smaller than corresponding flat surfaces. Spectral shifts of XRD signals indicate that residual stresses due to plasma exposure of micro-engineered surfaces build up in the first few cycles of exposure. Subsequent cyclic plasma heat loading is shown to anneal out most of the built-up residual stresses in micro-engineered surfaces. These findings are consistent with relaxation of residual thermal stresses in surfaces with micro-engineered features. The initial residual stress state of highly polished flat W samples is compressive (≈ -1.3 GPa). After exposure to 50 plasma cycles, the surface stress relaxes to -1.0 GPa. Micro-engineered samples exposed to the same thermal cycling show that the initial residual stress state is compressive at (- 250 MPa), and remains largely unchanged after plasma exposure.

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

    SciTech Connect

    Anders, Andre; Monteiro, Othon R.

    2003-04-10

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

  6. Oxygen plasma-treated thermoresponsive polymer surfaces for cell sheet engineering.

    PubMed

    Shimizu, Kazunori; Fujita, Hideaki; Nagamori, Eiji

    2010-06-01

    Although cell sheet tissue engineering is a potent and promising method for tissue engineering, an increase of mechanical strength of a cell sheet is needed for easy manipulation of it during transplantation or 3D tissue fabrication. Previously, we developed a cell sheet-polymer film complex that had enough mechanical strength that can be manipulated even by tweezers (Fujita et al., 2009. Biotechnol Bioeng 103(2): 370-377). We confirmed the polymer film involving a temperature sensitive polymer and extracellular matrix (ECM) proteins could be removed by lowering temperature after transplantation, and its potential use in regenerative medicine was demonstrated. However, the use of ECM proteins conflicted with high stability in long-term storage and low cost. In the present study, to overcome these drawbacks, we employed the oxygen plasma treatment instead of using the ECM proteins. A cast and dried film of thermoresponsive poly-N-isopropylacrylamide (PNIPAAm) was fabricated and treated with high-intensity oxygen plasma. The cells became possible to adhere to the oxygen plasma-treated PNIPAAm surface, whereas could not to the inherent surface of bulk PNIPAAm without treatment. Characterizations of the treated surface revealed the surface had high stability. The surface roughness, wettability, and composition were changed, depending on the plasma intensity. Interestingly, although bulk PNIPAAm layer had thermoresponsiveness and dissolved below lower critical solution temperature (LCST), it was found that the oxygen plasma-treated PNIPAAm surface lost its thermoresponsiveness and remained insoluble in water below LCST as a thin layer. Skeletal muscle C2C12 cells could be cultured on the oxygen plasma-treated PNIPAAm surface, a skeletal muscle cell sheet with the insoluble thin layer could be released in the medium, and thus the possibility of use of the cell sheet for transplantation was demonstrated.

  7. Regulating the antibiotic drug release from β-tricalcium phosphate ceramics by atmospheric plasma surface engineering.

    PubMed

    Canal, C; Modic, M; Cvelbar, U; Ginebra, M-P

    2016-10-20

    Calcium phosphate (CaP) ceramics are of interest in bone substitution due to their good biocompatibility and bioresorbability. Currently certain CaPs in the market are loaded with antibiotics in order to prevent infections but further control is needed over antibiotic release patterns. Cold plasmas have emerged as a useful means of modifying the interactions with drugs through surface modification of polymer materials. In this work we explore the possibility of using atmospheric pressure plasmas as a tool for the surface modification of these CaP materials with newly populated bonds and charges, with views on enabling higher loading and controlled drug release. Herein the surface modification of β-tricalcium phosphate ceramics is investigated using an atmospheric pressure helium plasma jet as a tool for tuning the controlled release of the antibiotic doxycycline hyclate, employed as a drug model. The surface chemistry is tailored mainly by plasma jet surface interaction with an increasing O/C ratio without changes in the topography as well as by build-up of surface charges. With this surface tailoring it is demonstrated that the atmospheric plasma jet is a new promising tool that leads to the design of a control for drug release from bioceramic matrices.

  8. Plasma engineering for MARS

    SciTech Connect

    Carlson, G.A.; Baldwin, D.E.; Barr, W.L.

    1983-03-24

    The two-year Mirror Advanced Reactor Study (MARS) has resulted in the conceptual design of a commercial, electricity-producing fusion reactor based on tandem mirror confinement. The physics basis for the MARS reactor was developed through work in two highly coupled areas of plasma engineering: magnetics and plasma performance.

  9. Surface modification of electrospun PLLA nanofibers by plasma treatment and cationized gelatin immobilization for cartilage tissue engineering.

    PubMed

    Chen, Jyh-Ping; Su, Chien-Hao

    2011-01-01

    Electrospun poly(lactic acid) (PLLA) nanofibers (NF) were modified with cationized gelatin (CG) to improve their compatibility with chondrocytes and to show in vitro and in vivo the potential applications of CG-grafted PLLA nanofibrous membranes (CG-PLLA NFM) as a cartilage tissue engineering scaffold. PLLA NF were first treated with oxygen plasma to introduce -COOH groups on the surface, followed by covalent grafting of CG molecules onto the fiber surface, using water-soluble carbodiimide as the coupling agent. The effects of CG grafting and properties of NFM were characterized by scanning electron microscopy (SEM), transmission electron microscopy, thermogravimetric analysis, atomic force microscope, X-ray photoelectron spectra and Fourier transform infrared spectroscopy. In vitro studies indicated that CG-PLLA NFM could enhance viability, proliferation and differentiation of rabbit articular chondrocytes compared with pristine PLLA NFM. SEM observations of the cell-scaffold construct confirmed the tight attachment of chondrocytes to CG-PLLA NF and in-growth of cells into the interior of the membrane with proper maintenance of cell morphology. Improved cell differentiation in CG-PLLA NFM was confirmed by enhanced glycoaminoglycan and collagen secretion, histological analysis and reverse transcription-polymerase chain reaction studies, which showed that the cells were able to maintain the expression of characteristic markers (collagen II, aggregan and SOX 9) of chondrocytes. Subcutaneous implantation of the cell-scaffold constructs with autologous chondrocytes also confirmed the formation of ectopic cartilage tissues after 28 days by histological examination and immunostaining.

  10. Plasma surface modification of polymers

    NASA Technical Reports Server (NTRS)

    Hirotsu, T.

    1980-01-01

    Thin plasma polymerization films are discussed from the viewpoint of simplicity in production stages. The application of selective, absorbent films and films used in selective permeability was tested. The types of surface modification of polymers discussed are: (1) plasma etching, (2) surface coating by plasma polymerized thin films, and (3) plasma activation surface graft polymerization.

  11. In vitro study of 3D PLGA/n-HAp/β-TCP composite scaffolds with etched oxygen plasma surface modification in bone tissue engineering

    NASA Astrophysics Data System (ADS)

    Roh, Hee-Sang; Jung, Sang-Chul; Kook, Min-Suk; Kim, Byung-Hoon

    2016-12-01

    Three-dimensional (3D) scaffolds have many advantageous properties for bone tissue engineering application, due to its controllable properties such as pore size, structural shape and interconnectivity. In this study, effects on oxygen plasma surface modification and adding of nano-hydroxyapatite (n-HAp) and β-tricalcium phosphate (β-TCP) on the 3D PLGA/n-HAp/β-TCP scaffolds for improving preosteoblast cell (MC3T3-E1) adhesion, proliferation and differentiation were investigated. The 3D PLGA/n-HAp/β-TCP scaffolds were fabricated by 3D Bio-Extruder equipment. The 3D scaffolds were prepared with 0°/90° architecture and pore size of approximately 300 μm. In addition 3D scaffolds surface were etched by oxygen plasma to enhance the hydrophilic property and surface roughness. After oxygen plasma treatment, the surface chemistry and morphology were investigated by Fourier transform infrared spectroscopy, scanning electron microscopy, and atomic force microscopy. And also hydrophilic property was measured by contact angle. The MC3T3-E1 cell proliferation and differentiation were investigated by MTT assay and ALP activity. In present work, the 3D PLGA/HAp/beta-TCP composite scaffold with suitable structure for the growth of osteoblast cells was successfully fabricated by 3D rapid prototyping technique. The surface hydrophilicity and roughness of 3D scaffold increased by oxygen plasma treatment had a positive effect on cell adhesion, proliferation, and differentiation. Furthermore, the differentiation of MC3T3-E1 cell was significantly enhanced by adding of n-HAp and β-TCP on 3D PLGA scaffold. As a result, combination of bioceramics and oxygen plasma treatment showed a synergistic effect on biocompatibility of 3D scaffolds. This result confirms that this technique was useful tool for improving the biocompatibility in bone tissue engineering application.

  12. Magnesium: Engineering the Surface

    NASA Astrophysics Data System (ADS)

    Chen, X. B.; Yang, H. Y.; Abbott, T. B.; Easton, M. A.; Birbilis, N.

    2012-06-01

    Magnesium (Mg) and its alloys provide numerous benefits as lightweight materials; however, industrial deployment of Mg in most instances requires anticorrosion coatings. Engineering the Mg surface is an area that has been undergoing intense research recently. Surface engineering commences with the "pretreatment" step, which can be used to modify the surface composition and morphology, resulting in surface enrichment or depletion of alloying elements. Following this, electrochemical plating (including electro- and electroless plating) and conversion coatings have emerged as common means of coating Mg. In this study, we present the key aspects relating to the science and technology associated with pretreatment, electrochemical plating, and conversion coatings. This is followed by experimental examples of engineered surfaces of industrial relevance.

  13. Plasma interactions and surface/material effects

    NASA Technical Reports Server (NTRS)

    Mandel, M.; Chutjian, A.; Hall, W.; Leung, P.; Robinson, P.; Stevens, N. J.

    1986-01-01

    A discussion on plasma interactions and surface/material effects is summarized. The key issues in this area were: (1) the lack of data on the material properties of common spacecraft surface materials; (2) lack of understanding of the contamination and decontamination processes; and (3) insufficient analytical tools to model synergistic phenomena related to plasma interactions. Without an adequate database of material properties, accurate system performance predictions cannot be made. The interdisciplinary nature of the surface-plasma interactions area makes it difficult to plan and maintain a coherent theoretical and experimental program. The shuttle glow phenomenon is an excellent example of an unanticipated, complex interaction involving synergism between surface and plasma effects. Building an adequate technology base for understanding and predicting surface-plasma interactions will require the coordinated efforts of engineers, chemists, and physicists. An interdisciplinary R and D program should be organized to deal with similar problems that the space systems of the 21st century may encounter.

  14. Plasma surface cleaning using microwave plasmas

    SciTech Connect

    Tsai, C.C.; Haselton, H.H.; Nelson, W.D.; Schechter, D.E.; Thompson, L.M.; Campbell, V.B.; Glover, A.L.; Googin, J.M.

    1993-11-01

    In a microwave electron cyclotron resonance (ECR) plasma source, reactive plasmas of oxygen and its mixture with argon are used for plasma-cleaning experiments. Aluminum test samples (0.95 {times} 1.9 cm) were coated with thin films ({le} 20 {mu}m in thickness) of Shell Vitrea oil and cleaned by using such reactive plasmas. The plasma cleaning was done in various discharge conditions with fixed microwave power, rf power, biased potential, gas pressures (0.5 and 5 mtorr), and operating time up to 35 min. The status of plasma cleaning has been monitored by using mass spectroscopy. Mass loss of the samples after plasma cleaning was measured to estimate cleaning rates. Measured clean rates of low pressure (0.5 mtorr) argon/oxygen plasmas were as high as 2.7 {mu}/min. X-ray photoelectron spectroscopy was used to determine cleanliness of the sample surfaces and confirm the effectiveness of plasma cleaning in achieving atomic levels of surface cleanliness. In this paper, significant results are reported and discussed.

  15. Plasma igniter for internal-combustion engines

    NASA Technical Reports Server (NTRS)

    Breshears, R. R.; Fitzgerald, D. J.

    1978-01-01

    Hot ionized gas (plasma) ignites air/fuel mixture in internal combustion engines more effectively than spark. Electromagnetic forces propel plasma into combustion zone. Combustion rate is not limited by flame-front speed.

  16. Plasma hardening of railway wheel surface

    NASA Astrophysics Data System (ADS)

    Isakaev, E. Kh.; Ivanov, P. P.; Tyuftyaev, A. S.; Paristyi, I. L.; Troitsky, A. A.; Yablonsky, A. E.; Filippov, G. A.

    1998-10-01

    A computer-controlled plasma technology was developed for the treatment of rolling stock wheels, providing the thermal hardening of tread and flange working surfaces. As a result of the plasma treatment the surface hardness of the wheel grows from 255 up to 420-450 HB. Herewith, the wear capability of the wheel metal grows 2-3 times and its resistance to the weariness-driven destruction grows 1.5 times due to the pecularities of the structural state of the steel, arising out of the thermal impact and of the alloying of the steel with nitrogen during the plasma treatment. Installation of several plants based on this technology in engine houses allowed to carry out a full scale experiment in order to assess the running characteristics of treated wheel sets in comparison with plain ones. Wheel life between mounting and truing or dismounting doubles due to plasma hardening.

  17. A Study of Test Techniques for Evaluating Ablative Plasma Engines in Vacuum Test Cells

    DTIC Science & Technology

    1981-10-01

    windows as shown. A small light source was placed at the plasma engine face and the spectrometer was adjusted until the image of the source was...engine pulses. Since the flat face of the calorimeter is completely immersed in the plasma , then if the energy transfer is independent of the...that the plasma impinged on the’ outer surface as the apex faced the engine or on the inner surface as the open base faced the engine. Three

  18. Functionalising surfaces at the nanoscale using plasma technology.

    PubMed

    Moore, R

    2009-01-01

    Plasma technology offers a highly effective toolbox for nanoscale surface engineering of materials. The potential variety of nanoscale features and new properties that can be achieved are reviewed here.

  19. Atmospheric Plasma for Surface Modification

    DTIC Science & Technology

    2011-02-01

    Plasma for Surface Modification 5a. CONTRACT NUMBER 5b. GRANT NUMBER 5c. PROGRAM ELEMENT NUMBER 6. AUTHOR(S) 5d. PROJECT NUMBER 5e. TASK NUMBER 5f...barrier coatings, dry low friction surfaces • Deposition Polymerized hydrocarbon coatings, chemical barriers, scratch resistant coatings, glass-like... surfaces , diamond like films • Oxidation/reduction Organic and inorganic functionalities • Activation. Hydroxyl, carboxylic, carbonyl, amine, vinyl

  20. Lightweight Portable Plasma Medical Device - Plasma Engineering Research Laboratory

    DTIC Science & Technology

    2015-12-01

    polymer films used in biomedical applications such as polyethylene terephthalate (PET) and poly-L-lactide (PLLA) samples continuously for several...such as surface treatment of polymers , biomedical and environmental applications where OES act as a key diagnostic for investigating the plasma...low gas temperature of the plasma jet and its suitability for biomedical applications and surface treatment of bio- polymers . The plasma jet was tested

  1. Novel application of plasma treatment for pharmaceutical and biomedical engineering.

    PubMed

    Kuzuya, Masayuki; Sasai, Yasushi; Kondo, Shin-Ichi; Yamauchi, Yukinori

    2009-06-01

    The nature of plasma-induced surface radicals formed on a variety of organic polymers has been studied by electron spin resonance (ESR), making it possible to provide a sound basis for future experimental design of polymer surface processing using plasma treatment. On the basis of the findings from such studies, several novel bio-applications in the field of drug- and biomedical- engineering have been developed. Applications for drug engineering include the preparation of reservoir-type drug delivery system (DDS) of sustained- and delayed-release, and floating drug delivery system (FDDS) possessing gastric retention capabilities, followed by preparation of "Patient-Tailored DDS". Furthermore, the preparation of composite powders applicable to matrix-type DDS was developed by making a mechanical application to the surface radical-containing polymer powders with drug powders. In applications for biomedical engineering, the novel method to introduce the durable surface hydrophilicity and lubricity on hydrophobic biomedical polymers was developed by plasma-assisted immobilization of carboxyl group-containing polymer on the polymer substrate. The surfaces thus prepared were further used for the covalent immobilization of oligo-nucleotides (DNA) onto the polymer surfaces applicable to constructing DNA diagnosis system, and also plasma-assisted preparation of functionalized chemo-embolic agent of vinyl alcohol-sodium acrylate copolymer (PVA- PAANa).

  2. Gas Plasma Surface Chemistry for Biological Assays.

    PubMed

    Sahagian, Khoren; Larner, Mikki

    2015-01-01

    Biological systems respond to and interact with surfaces. Gas plasma provides a scalable surface treatment method for designing interactive surfaces. There are many commercial examples of plasma-modified products. These include well plates, filtration membranes, dispensing tools, and medical devices. This chapter presents an overview of gas plasma technology and provides a guide to using gas plasma for modifying surfaces for research or product development.

  3. Inductively coupled plasma source for VASIMR engine

    NASA Astrophysics Data System (ADS)

    Godyak, V. A.; Smolyakov, A. I.; Sydorenko, D. Y.; Sagdeev, R. Z.; Krasheninnikov, S. I.; Shevchenko, V. I.

    2004-11-01

    Various devices for plasma production differ in the way of plasma coupling to the electrical energy source. Power losses in the chain from the AC power line to the power deposited into the electrons are the most important for the overall efficiency of the plasma source while the losses to ionization, radiation and walls are typically very similar and do not depend on a mechanism of the electron interaction with the electromagnetic field. Inductively coupled plasma (ICP) discharges with ferromagnetic cores, seems to be the most suitable candidate for a primary plasma source for VASIMR engine. Such commercial ICPs have coupling efficiency up to 98% (99% in laboratory devices). Combined with compact and efficient (90-95%) rf power converters operating at f < 1 MHz, it will allow to achieve high overall efficiency of plasma production and reduce the energy cost of the ion in the first stage plasma source. An important advantage of such sources is the ability to continuously work in a wide dynamic range (two orders of magnitude) of plasma density contrary to e.g. helicon sources where efficient operation is possible only on certain discrete modes (and plasma density) with discontinuous transitions between them.

  4. Argonne Plasma Engineering Experiment (APEX) Tokamak

    SciTech Connect

    Norem, J.H.; Balka, L.J.; Kulovitz, E.E.; Magill, S.R.; McGhee, D.G.; Moretti, A.; Praeg, W.F.

    1981-03-01

    The Argonne Plasma Engineering Experiment (APEX) Tokamak was designed to provide hot plasmas for reactor-relevant experiments with rf heating (current drive) and plasma wall experiments, principally in-situ low-Z wall coating and maintenance. The device, sized to produce energetic plasmas at minimum cost, is small (R = 51 cm, r = 15 cm) but capable of high currents (100 kA) and long pulse durations (100 ms). A design using an iron central core with no return legs, pure tension tapewound toroidal field coils, digital radial position control, and UHV vacuum technology was used. Diagnostics include monochrometers, x-ray detectors, and a microwave interferometer and radiometer for density and temperature measurements. Stable 100 ms shots were produced with electron temperatures in the range 500 to 1000 eV. Initial results included studies of thermal desorption and recoating of wall materials.

  5. Plasma Diagnostics Development for Advanced Rocket Engines

    NASA Astrophysics Data System (ADS)

    Glover, Timothy; Kittrell, Carter; Chan, Anthony; Chang-Diaz, Franklin

    2000-10-01

    The VASIMR (Variable Specific Impulse Magnetoplasma Rocket) engine is a next-generation rocket engine under development at the Johnson Space Center's Advanced Space Propulsion Laboratory. With an exhaust velocity up to 50 times that of chemical rocket engines such as the Space Shuttle Main Engine, the VASIMR concept promises fast, efficient interplanetary flight. Rice University has participated in VASIMR research since 1996 and at present is developing two new diagnostic probes: a retarding potential analyzer to measure the velocity of ions in the rocket's exhaust, and a moveable optical probe to examine the spectrum of the rocket's helicon plasma source. In support of the probe development, a test facility is under construction at Rice, consisting of a small electric rocket engine firing into a 2-m vacuum chamber. This engine, the MPD (magnetoplasmadynamic) thruster, dates from the 1960's and provides a well-characterized source plasma for testing of the probes under development. We present details of the ion energy analyzer and the facility under construction at Rice.

  6. Practical applications of plasma surface modification

    SciTech Connect

    Smith, M.D.

    1993-12-01

    Radio frequency activated gas plasma is an environmentally conscious manufacturing process which provides surface treatments for improved product quality. Plasma processing offers significant potential for reducing the use of solvents and other wet processing chemicals now used in surface treatments such as cleaning, activation for bonding, and moisture removal. Plasma treatments are generally accomplished without creating hazardous waste streams to dispose of. Plasma process development and application is ongoing at Allied Signal Inc., Kansas City Division.

  7. Dispersion engineering of surface plasmons.

    PubMed

    Mandel, Isroel M; Bendoym, Igor; Jung, Young U; Golovin, Andrii B; Crouse, David T

    2013-12-30

    In this work, it is shown how the shapes of surface plasmon dispersion curves can be engineered by manipulating the distribution of the electromagnetic fields in multilayer structures, which themselves are controlled by the free electron density in metal-like materials, such as doped semiconductors in the THz spectral range. By having a nonuniform free electron density profile, reduced relative to that in typical bulk metals, the electromagnetic fields of surface plasmons are distributed in different metallic materials that have different complex dielectric permittivities. As the in-plane component of surface plasmon's wave-vector increases, they become more confined to a particular layer of the multilayer structure and have energies that are predictable by considering the permittivity of the layer in which the fields are most concentrated. Unusual and arbitrary shapes of surface plasmon dispersion curves can be designed, including stair steps and dovetails shapes.

  8. Kansei, surfaces and perception engineering

    NASA Astrophysics Data System (ADS)

    Rosen, B.-G.; Eriksson, L.; Bergman, M.

    2016-09-01

    The aesthetic and pleasing properties of a product are important and add significantly to the meaning and relevance of a product. Customer sensation and perception are largely about psychological factors. There has been a strong industrial and academic need and interest for methods and tools to quantify and link product properties to the human response but a lack of studies of the impact of surfaces. In this study, affective surface engineering is used to illustrate and model the link between customer expectations and perception to controllable product surface properties. The results highlight the use of the soft metrology concept for linking physical and human factors contributing to the perception of products. Examples of surface applications of the Kansei methodology are presented from sauna bath, health care, architectural and hygiene tissue application areas to illustrate, discuss and confirm the strength of the methodology. In the conclusions of the study, future research in soft metrology is proposed to allow understanding and modelling of product perception and sensations in combination with a development of the Kansei surface engineering methodology and software tools.

  9. Plasma igniter for internal combustion engine

    NASA Technical Reports Server (NTRS)

    Fitzgerald, D. J.; Breshears, R. R. (Inventor)

    1978-01-01

    An igniter for the air/fuel mixture used in the cylinders of an internal combustion engine is described. A conventional spark is used to initiate the discharge of a large amount of energy stored in a capacitor. A high current discharge of the energy in the capacitor switched on by a spark discharge produces a plasma and a magnetic field. The resultant combined electromagnetic current and magnetic field force accelerates the plasma deep into the combustion chamber thereby providing an improved ignition of the air/fuel mixture in the chamber.

  10. A review of Soviet plasma engine development

    NASA Technical Reports Server (NTRS)

    Barnett, John W.

    1990-01-01

    The Soviet Union has maintained a substantial and successful electric propulsion research and development effort since the 1950s; however, American researchers are generally unfamiliar with the Soviet accomplishments. Sources of information about Soviet electric propulsion research are noted. The development of plasma engines, a subset of the electric propulsion effort, is reviewed using numerous Soviet sources. The operational principles and status of several engines of the closed electron drift and high-current types are discussed. With recognition of the limited knowledge of the current Soviet program, the Soviet and American programs are compared, revealing some differences in program formulation and emphasis.

  11. Antiproton powered propulsion with magnetically confined plasma engines

    SciTech Connect

    Lapointe, M.R.

    1989-08-01

    Matter-antimatter annihilation releases more energy per unit mass than any other method of energy production, making it an attractive energy source for spacecraft propulsion. In the magnetically confined plasma engine, antiproton beams are injected axially into a pulsed magnetic mirror system, where they annihilate with an initially neutral hydrogen gas. The resulting charged annihilation products transfer energy to the hydrogen propellant, which is then exhausted through one end of the pulsed mirror system to provide thrust. The calculated energy transfer efficiencies for a low number density (10(14)/cu cm) hydrogen propellant are insufficient to warrant operating the engine in this mode. Efficiencies are improved using moderate propellant number densities (10(16)/cu cm), but the energy transferred to the plasma in a realistic magnetic mirror system is generally limited to less than 2 percent of the initial proton-antiproton annihilation energy. The energy transfer efficiencies are highest for high number density (10(18)/cu cm) propellants, but plasma temperatures are reduced by excessive radiation losses. Low to moderate thrust over a wide range of specific impulse can be generated with moderate propellant number densities, while higher thrust but lower specific impulse may be generated using high propellant number densities. Significant mass will be required to shield the superconducting magnet coils from the high energy gamma radiation emitted by neutral pion decay. The mass of such a radiation shield may dominate the total engine mass, and could severely diminish the performance of antiproton powered engines which utilize magnetic confinement. The problem is compounded in the antiproton powered plasma engine, where lower energy plasma bremsstrahlung radiation may cause shield surface ablation and degradation.

  12. Antiproton powered propulsion with magnetically confined plasma engines

    NASA Technical Reports Server (NTRS)

    Lapointe, Michael R.

    1989-01-01

    Matter-antimatter annihilation releases more energy per unit mass than any other method of energy production, making it an attractive energy source for spacecraft propulsion. In the magnetically confined plasma engine, antiproton beams are injected axially into a pulsed magnetic mirror system, where they annihilate with an initially neutral hydrogen gas. The resulting charged annihilation products transfer energy to the hydrogen propellant, which is then exhausted through one end of the pulsed mirror system to provide thrust. The calculated energy transfer efficiencies for a low number density (10(14)/cu cm) hydrogen propellant are insufficient to warrant operating the engine in this mode. Efficiencies are improved using moderate propellant number densities (10(16)/cu cm), but the energy transferred to the plasma in a realistic magnetic mirror system is generally limited to less than 2 percent of the initial proton-antiproton annihilation energy. The energy transfer efficiencies are highest for high number density (10(18)/cu cm) propellants, but plasma temperatures are reduced by excessive radiation losses. Low to moderate thrust over a wide range of specific impulse can be generated with moderate propellant number densities, while higher thrust but lower specific impulse may be generated using high propellant number densities. Significant mass will be required to shield the superconducting magnet coils from the high energy gamma radiation emitted by neutral pion decay. The mass of such a radiation shield may dominate the total engine mass, and could severely diminish the performance of antiproton powered engines which utilize magnetic confinement. The problem is compounded in the antiproton powered plasma engine, where lower energy plasma bremsstrahlung radiation may cause shield surface ablation and degradation.

  13. Solitary surface waves on a plasma cylinder

    NASA Astrophysics Data System (ADS)

    Gradov, O. M.; Stenflo, L.

    1983-03-01

    By considering electrostatic surface waves propagating along a plasma cylinder, it is demonstrated that solitary variations in the cylinder radius may appear. The properties of these slow perturbations are determined by the surface wave intensities.

  14. 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.

  15. Surface modification of polymeric materials by cold atmospheric plasma jet

    NASA Astrophysics Data System (ADS)

    Kostov, K. G.; Nishime, T. M. C.; Castro, A. H. R.; Toth, A.; Hein, L. R. O.

    2014-09-01

    In this work we report the surface modification of different engineering polymers, such as, polyethylene terephthalate (PET), polyethylene (PE) and polypropylene (PP) by an atmospheric pressure plasma jet (APPJ). It was operated with Ar gas using 10 kV, 37 kHz, sine wave as an excitation source. The aim of this study is to determine the optimal treatment conditions and also to compare the polymer surface modification induced by plasma jet with the one obtained by another atmospheric pressure plasma source - the dielectric barrier discharge (DBD). The samples were exposed to the plasma jet effluent using a scanning procedure, which allowed achieving a uniform surface modification. The wettability assessments of all polymers reveal that the treatment leads to reduction of more than 40° in the water contact angle (WCA). Changes in surface composition and chemical bonding were analyzed by x-ray photoelectron spectroscopy (XPS) and Fourier-Transformed Infrared spectroscopy (FTIR) that both detected incorporation of oxygen-related functional groups. Surface morphology of polymer samples was investigated by Atomic Force Microscopy (AFM) and an increase of polymer roughness after the APPJ treatment was found. The plasma-treated polymers exhibited hydrophobic recovery expressed in reduction of the O-content of the surface upon rinsing with water. This process was caused by the dissolution of low molecular weight oxidized materials (LMWOMs) formed on the surface as a result of the plasma exposure.

  16. Dust release from surfaces exposed to plasma

    SciTech Connect

    Flanagan, T. M.; Goree, J.

    2006-12-15

    Micrometer-sized particles adhered to a surface can be released when exposed to plasma. In an experiment with a glass surface coated with lunar-simulant dust, it was found that particle release requires exposure to both plasma and an electron beam. The dust release rate diminishes almost exponentially in time, which is consistent with a random process. As proposed here, charges of particles adhered to the surface fluctuate. These charges experience a fluctuating electric force that occasionally overcomes the adhesive van der Waals force, causing particle release. The release rate increases with plasma density, so that plasma cleaning is feasible at high plasma densities. Applications of this cleaning include controlling particulate contamination in semiconductor manufacturing, dust mitigation in the exploration of the moon and Mars, and dusty plasmas.

  17. Plasma power recycling at the divertor surface

    SciTech Connect

    Tang, Xian -Zhu; Guo, Zehua

    2016-12-03

    With a divertor made of solid materials like carbon and tungsten, plasma ions are expected to be recycled at the divertor surface with a time-averaged particle recycling coefficient very close to unity in steady-state operation. This means that almost every plasma ion (hydrogen and helium) will be returned to the plasma, mostly as neutrals. The power flux deposited by the plasma on the divertor surface, on the other hand, can have varying recycling characteristics depending on the material choice of the divertor; the run-time atomic composition of the surface, which can be modified by material mix due to impurity migration in the chamber; and the surface morphology change over time. In general, a high-Z–material (such as tungsten) surface tends to reflect light ions and produce stronger power recycling, while a low-Z–material (such as carbon) surface tends to have a larger sticking coefficient for light ions and hence lower power recycling. Here, an explicit constraint on target plasma density and temperature is derived from the truncated bi-Maxwellian sheath model, in relation to the absorbed power load and power recycling coefficient at the divertor surface. Lastly, it is shown that because of the surface recombination energy flux, the attached plasma has a sharper response to power recycling in comparison to a detached plasma.

  18. Plasma power recycling at the divertor surface

    DOE PAGES

    Tang, Xian -Zhu; Guo, Zehua

    2016-12-03

    With a divertor made of solid materials like carbon and tungsten, plasma ions are expected to be recycled at the divertor surface with a time-averaged particle recycling coefficient very close to unity in steady-state operation. This means that almost every plasma ion (hydrogen and helium) will be returned to the plasma, mostly as neutrals. The power flux deposited by the plasma on the divertor surface, on the other hand, can have varying recycling characteristics depending on the material choice of the divertor; the run-time atomic composition of the surface, which can be modified by material mix due to impurity migrationmore » in the chamber; and the surface morphology change over time. In general, a high-Z–material (such as tungsten) surface tends to reflect light ions and produce stronger power recycling, while a low-Z–material (such as carbon) surface tends to have a larger sticking coefficient for light ions and hence lower power recycling. Here, an explicit constraint on target plasma density and temperature is derived from the truncated bi-Maxwellian sheath model, in relation to the absorbed power load and power recycling coefficient at the divertor surface. Lastly, it is shown that because of the surface recombination energy flux, the attached plasma has a sharper response to power recycling in comparison to a detached plasma.« less

  19. Surface plasma source with anode layer plasma accelerator

    SciTech Connect

    Dudnikov, Vadim

    2012-02-15

    Proposed plasma generation system can be used for high current negative ion beam production and for directed deposition by flux of sputtered neutrals and negative ions. The main mechanism of negative ion formation in surface plasma sources is the secondary emission from low work function surface bombarded by a flux of positive ion or neutrals. The emission of negative ions is enhanced significantly by introducing a small amount of cesium or other substance with low ionization potential. In the proposed source are used positive ions generated by Hall drift plasma accelerator (anode layer plasma accelerator or plasma accelerator with insulated channel, with cylindrical or race track configuration of emission slit). The target-emitter is bombarded by the ion beam accelerated in crossed ExB fields. Negative ions are extracted from the target surface with geometrical focusing and are accelerated by negative voltage applied between emitter and plasma, contacting with the plasma accelerator. Hall drift ion source has a special design with a space for passing of the emitted negative ions and sputtered particles through the positive ion source.

  20. Peculiarities of surface plasmons in quantum plasmas

    NASA Astrophysics Data System (ADS)

    Tyshetskiy, Yuriy O.; Vladimirov, S. V.; Kompaneets, R.; Kompaneets

    2013-08-01

    Surface plasmons (SP) in a semi-bounded quantum plasma with degenerate electrons (e.g. a metal) are considered, and some interesting consequences of electron Pauli blocking for the SP dispersion and temporal attenuation are discussed. In particular, it is demonstrated that a semi-bounded degenerate plasma with a sharp boundary supports two types of SP with distinct frequencies and qualitatively different temporal attenuation, in contrast to a non-degenerate hot plasma that only supports one type of SP.

  1. Surface-Plasma Interaction on the Moon

    SciTech Connect

    Horanyi, M.; Wang, X.; Robertson, S.; Sternovsky, Z.

    2008-09-07

    The electrostatic levitation and transport of lunar dust remains a controversial science issue since the Apollo era. As a function of time and location, the lunar surface is exposed to solar wind plasma, UV radiation, and/or the plasma environment of our magnetosphere. Dust grains on the lunar surface emit and absorb plasma particles and are exposed to solar UV photons. There are several in situ and remote sensing observations that indicate that dusty plasma processes are responsible for the mobilization and transport of lunar soil. We briefly discuss the existing observations, and report on a series of experiments that address some of the most relevant processes acting on dusty surfaces exposed to plasmas and UV radiation.

  2. Overview of surface engineering and wear

    SciTech Connect

    Budinski, K.G.

    1996-12-31

    Surface engineering is a multidiscipline activity aimed at tailoring the properties or surfaces of engineering materials to improve their function or service life. As applied to metals, surface engineering includes processes such as plating, diffusion treatment, physical and chemical vapor deposition, ion implantation, thermal spray coatings, selective hardening, hardfacing, and a variety of less-used and proprietary processes. These processes will be described briefly and it is shown that each process has a niche where it works better or is more cost effective than competing surface engineering treatments or bulk materials. This paper reviews the various forms of wear that occur in industrial environments. Techniques are described to match available surface engineering processes with wear situations. The goal is to present selection guidelines for machine designers and industrial operating personnel on the use of surface engineering to solve wear problems.

  3. Diagnostics of plasma-surface interactions in plasma processes

    NASA Astrophysics Data System (ADS)

    Ishikawa, Kenji

    2014-10-01

    Low temperature plasma including electrons, ions, radicals and photons can be applied because only high temperature of electron but for background gases. Recently plasma applications in biology and medicine have grown significantly. For complexity of mechanisms, it is needed to understand comprehensively the plasma-surface interactions. To diagnose the interactions comprises of three areas; (1) incident species generated in plasmas toward the surface, (2) surface reactions such as scission and bond of chemical bonds, and (3) products after the reactions. Considered with non-linearity of the chemical reactions as changed by an initial state, we have focused and developed to observe dangling bonds in situ at real time by electron spin resonance (ESR). Moreover, individual contribution and simultaneous irradiation of each species such as radicals and photons have been studied in utilization of light shades and windows in similar manner of the pellets for plasma process evaluation (PAPE). As exampled, the interaction of polymeric materials, fungal spores and edible meats with plasmas were studied on the basis of the real time in situ observations of dangling bonds or surface radicals formation.

  4. Plasma Igniter for Reliable Ignition of Combustion in Rocket Engines

    NASA Technical Reports Server (NTRS)

    Martin, Adam; Eskridge, Richard

    2011-01-01

    A plasma igniter has been developed for initiating combustion in liquid-propellant rocket engines. The device propels a hot, dense plasma jet, consisting of elemental fluorine and fluorine compounds, into the combustion chamber to ignite the cold propellant mixture. The igniter consists of two coaxial, cylindrical electrodes with a cylindrical bar of solid Teflon plastic in the region between them. The outer electrode is a metal (stainless steel) tube; the inner electrode is a metal pin (mild steel, stainless steel, tungsten, or thoriated-tungsten). The Teflon bar fits snugly between the two electrodes and provides electrical insulation between them. The Teflon bar may have either a flat surface, or a concave, conical surface at the open, down-stream end of the igniter (the igniter face). The igniter would be mounted on the combustion chamber of the rocket engine, either on the injector-plate at the upstream side of the engine, or on the sidewalls of the chamber. It also might sit behind a valve that would be opened just prior to ignition, and closed just after, in order to prevent the Teflon from melting due to heating from the combustion chamber.

  5. Incorporating swarm data into plasma models and plasma surface interactions

    NASA Astrophysics Data System (ADS)

    Makabe, Toshiaki

    2009-10-01

    Since the mid-1980s, modeling of non-equilibrium plasmas in a collisional region driven at radio frequency has been developed at pressure greater than ˜Pa. The collisional plasma has distinct characteristics induced by a quantum property of each of feed gas molecules through collisions with electrons or heavy particles. That is, there exists a proper function caused by chemically active radicals, negative-ions, and radiations based on a molecular quantum structure through short-range interactions mainly with electrons. This differs from high-density, collisionless plasma controlled by the long-range Coulomb interaction. The quantum property in the form of the collision cross section is the first essential through swarm parameters in order to investigate the collisional plasma structure and to predict the function. These structure and function, of course, appear under a self- organized spatiotemporal distribution of electrons and positive ions subject to electromagnetic theory, i.e., bulk-plasma and ion-sheath. In a plasma interacting with a surface, the flux, energy and angle of particles incident on a surface are basic quantities. It will be helpful to learn the limits of the swarm data in a quasi-equilibrium situation and to find a way out of the difficulty, when we predict the collisional plasma, the function, and related surface processes. In this talk we will discuss some of these experiences in the case of space and time varying radiofrequency plasma and the micro/nano-surface processes. This work is partly supported by Global-COE program in Keio University, granted by MEXT Japan.

  6. Measurements of an expanding surface flashover plasma

    SciTech Connect

    Harris, J. R.

    2014-05-21

    A better understanding of vacuum surface flashover and the plasma produced by it is of importance for electron and ion sources, as well as advanced accelerators and other vacuum electronic devices. This article describes time-of-flight and biased-probe measurements made on the expanding plasma generated from a vacuum surface flashover discharge. The plasma expanded at velocities of 1.2–6.5 cm/μs, and had typical densities of 10{sup 10}–10{sup 12} cm{sup −3}. The expansion velocity of the plasma leading edge often exhibited a sharp increase at distances of about 50 mm from the discharge site. Comparison with biased-probe data suggests that, under most conditions, the plasma leading edge was dominated by negative ions, with the apparent increase in velocity being due to fast H{sup −} overtaking slower, heavier ions. In some cases, biased-probe data also showed abrupt discontinuities in the plasma energy distribution co-located with large changes in the intercepted plasma current, suggesting the presence of a shock in the leading edge of the expanding plasma.

  7. Characteristics of Surface Sterilization using ECR Plasma

    NASA Astrophysics Data System (ADS)

    Yonesu, Akira; Hara, Kazufumi; Nishikawa, Tatsuya; Hayashi, Nobuya

    2015-09-01

    Plasma sterilization techniques have superior characteristics such as a short treatment times, non-toxicity and low thermal damages on the sterilized materials. In plasma sterilization, microorganisms can be sterilized by active radicals, energetic charged particles, and vacuum UV radiation. The influence of each factor depends on the plasma operating parameters. Microwave discharges under the electron cyclotron resonance (ECR) condition produce higher electron temperature and density plasma as compared with other plasma generation techniques. In the present study, characteristics of surface sterilization using ECR plasma have been investigated.The experiment was performed in the vacuum chamber which contains a magnet holder. A pair of rectangular Sm-Co permanent magnets is aligned parallel to each other within the magnet holder. The region of the magnetic field for ECR exists near the magnet holder surface. When the microwave is introduced into the vacuum chamber, a ECR plasma is produced around surface of the magnet holder. High energy electrons and oxygen radicals were observed at ECR zone by electric probe method and optical spectroscopic method. Biological indicators (B.I.) having spore of 106 was sterilized in 2min for oxygen discharge. The temperature of the B.I. installation position was about 55°. The sterilization was achieved by the effect of oxygen radicals and high energy electrons.

  8. Surface plasma source with saddle antenna radio frequency plasma generator

    SciTech Connect

    Dudnikov, V.; Johnson, R. P.; Murray, S.; Pennisi, T.; Piller, C.; Santana, M.; Stockli, M.; Welton, R.

    2012-02-15

    A prototype RF H{sup -} surface plasma source (SPS) with saddle (SA) RF antenna is developed which will provide better power efficiency for high pulsed and average current, higher brightness with longer lifetime and higher reliability. Several versions of new plasma generators with small AlN discharge chambers and different antennas and magnetic field configurations were tested in the plasma source test stand. A prototype SA SPS was installed in the Spallation Neutron Source (SNS) ion source test stand with a larger, normal-sized SNS AlN chamber that achieved unanalyzed peak currents of up to 67 mA with an apparent efficiency up to 1.6 mA/kW. Control experiments with H{sup -} beam produced by SNS SPS with internal and external antennas were conducted. A new version of the RF triggering plasma gun has been designed. A saddle antenna SPS with water cooling is fabricated for high duty factor testing.

  9. Surface plasma source with saddle antenna radio frequency plasma generator.

    PubMed

    Dudnikov, V; Johnson, R P; Murray, S; Pennisi, T; Piller, C; Santana, M; Stockli, M; Welton, R

    2012-02-01

    A prototype RF H(-) surface plasma source (SPS) with saddle (SA) RF antenna is developed which will provide better power efficiency for high pulsed and average current, higher brightness with longer lifetime and higher reliability. Several versions of new plasma generators with small AlN discharge chambers and different antennas and magnetic field configurations were tested in the plasma source test stand. A prototype SA SPS was installed in the Spallation Neutron Source (SNS) ion source test stand with a larger, normal-sized SNS AlN chamber that achieved unanalyzed peak currents of up to 67 mA with an apparent efficiency up to 1.6 mA∕kW. Control experiments with H(-) beam produced by SNS SPS with internal and external antennas were conducted. A new version of the RF triggering plasma gun has been designed. A saddle antenna SPS with water cooling is fabricated for high duty factor testing.

  10. Plasma Sensor Measurements in Pulse Detonation Engines

    NASA Astrophysics Data System (ADS)

    Matlis, Eric; Marshall, Curtis; Corke, Thomas; Gogineni, Sivaram

    2014-11-01

    Measurements have been conducted in a pulse detonation and rotating detonation engine using a newly developed plasma sensor. This sensor relies on the novel approach of using an ac-driven, weakly-ionized electrical discharge as the main sensing element. The advantages of this approach include a native high bandwidth of 1 MHz without the need for electronic frequency compensation, a dual-mode capability that provides sensitivity to multiple flow parameters, including velocity, pressure, temperature, and gas-species, and a simple and robust design making it very cost effective. The sensor design is installation-compatible with conventional sensors commonly used in gas-turbine research such as the Kulite dynamic pressure sensor while providing much better longevity. Developmental work was performed in high temperature facilities that are relevant to the propulsion and high-speed research community. This includes tests performed in a J85 augmentor at full afterburner and pulse-detonation engines at the University of Cincinnati (UC) at temperatures approaching 2760°C (5000°F).

  11. The Lunar Surface: A Dusty Plasma Laboratory

    NASA Astrophysics Data System (ADS)

    Horanyi, M.; Brain, D.; Kempf, S.; Munsat, T.; Robertson, S. H.; Sternovsky, Z.

    2011-12-01

    The lunar surface is an excellent laboratory to study dusty plasma processes that are relevant to all airless planetary objects. The solar wind and UV radiation lead to charging of exposed surfaces, and the formation of plasma sheaths above them. Near-surface intense electric fields are thought to be capable of mobilizing and transporting small charged dust particles. Remote sensing and in situ observations indicating dust transport on the Moon date back to the Apollo era and remain highly controversial. There are many unresolved issues about the physical processes that have to this point prevented the development of a coherent explanation for the existing observations. Dust transport on airless bodies can significantly alter our interpretation of spectral identification of asteroids, the small-scale surface features of Mercury, and the Martian moons Phobos and Deimos. Understanding the behavior of dust laden plasma sheaths is of interest in basic plasma and planetary sciences, and holds the key to efficient dust hazard mitigation for the long-term use of optical and mechanical equipment used for robotic and/or human exploration. NASA Lunar Science Institute's Colorado Center of Lunar Dust is focused on experimental and theoretical investigations of dusty plasmas, and the effects of hypervelocity dust impacts on surfaces. This presentation will describe a series of small-scale laboratory experiments investigating the properties of photoelectron sheaths, and the emergence of intense electric fields near boundaries of lit and dark surfaces and regions shielded and exposed to the solar wind plasma flow. Our progress in the analysis and interpretation of the laboratory observations using simple analytic models and complex plasma simulation tools indicates that these models can be used to predict the expected properties of the lunar near-surface environment with increasing confidence. Based on our laboratory and theoretical efforts, we will also report on the status of

  12. Plasma-assisted interface engineering of boron nitride nanostructure films.

    PubMed

    Pakdel, Amir; Bando, Yoshio; Golberg, Dmitri

    2014-10-28

    Today many aspects of science and technology are progressing into the nanoscale realm where surfaces and interfaces are intrinsically important in determining properties and performances of materials and devices. One familiar phenomenon in which interfacial interactions play a major role is the wetting of solids. In this work we use a facile one-step plasma method to control the wettability of boron nitride (BN) nanostructure films via covalent chemical functionalization, while their surface morphology remains intact. By tailoring the concentration of grafted hydroxyl groups, superhydrophilic, hydrophilic, and hydrophobic patterns are created on the initially superhydrophobic BN nanosheet and nanotube films. Moreover, by introducing a gradient of the functional groups, directional liquid spreading toward increasing [OH] content is achieved on the films. The resulting insights are meant to illustrate great potentials of this method to tailor wettability of ceramic films, control liquid flow patterns for engineering applications such as microfluidics and biosensing, and improve the interfacial contact and adhesion in nanocomposite materials.

  13. A dc Penning Surface-Plasma Source

    DTIC Science & Technology

    2007-11-02

    LA-UR-93-2990 Title: A dc Penning Surface-Plasma Source Author(s): Submitted to: H. Vernon Smith, Jr., Paul Allison, Carl Geisik, David R...Type: HC Number of Copies In Library: 000001 Record ID: 28620 A de Penning Surface-Plasma Source* H. Vernon Smith, Jr., Paul Allison, Carl Geisik...Schechter, J. H. Whealton, and J. J. Donaghy, ATP Conf. Proc. No. 158, 366 (1987). 8) H. V. Smith, Jr., N. M. Schnurr, D. H. Whitaker , and K. E. Kalash

  14. Plasma-modified and polyethylene glycol-grafted polymers for potential tissue engineering applications.

    PubMed

    Svorcík, V; Makajová, Z; Kasálková-Slepicková, N; Kolská, Z; Bacáková, L

    2012-08-01

    Modified and grafted polymers may serve as building blocks for creating artificial bioinspired nanostructured surfaces for tissue engineering. Polyethylene (PE) and polystyrene (PS) were modified by Ar plasma and the surface of the plasma activated polymers was grafted with polyethylene glycol (PEG). The changes in the surface wettability (contact angle) of the modified polymers were examined by goniometry. Atomic Force Microscopy (AFM) was used to determine the surface roughness and morphology and electrokinetical analysis (Zeta potential) characterized surface chemistry of the modified polymers. Plasma treatment and subsequent PEG grafting lead to dramatic changes in the polymer surface morphology, roughness and wettability. The plasma treated and PEG grafted polymers were seeded with rat vascular smooth muscle cells (VSMCs) and their adhesion and proliferation were studied. Biological tests, performed in vitro, show increased adhesion and proliferation of cells on modified polymers. Grafting with PEG increases cell proliferation, especially on PS. The cell proliferation was shown to be an increasing function of PEG molecular weight.

  15. Polymer surface modification by plasmas and photons

    NASA Astrophysics Data System (ADS)

    Chan, C.-M.; Ko, T.-M.; Hiraoka, H.

    1996-05-01

    Polymers have been applied successfully in fields such as adhesion, biomaterials, protective coatings, friction and wear, composites, microelectronic devices, and thin-film technology. In general, special surface properties with regard to chemical composition, hydrophilicity, roughness, crystallinity, conductivity, lubricity, and cross-linking density are required for the success of these applications. Polymers very often do not possess the surface properties needed for these applications. However, they have excellent bulk physical and chemical properties, are inexpensive, and are easy to process. For these reasons, surface modification techniques which can transform these inexpensive materials into highly valuable finished products have become an important part of the plastics and many other industries. In recent years, many advances have been made in developing surface treatments to alter the chemical and physical properties of polymer surfaces without affecting bulk properties. Common surface modification techniques include treatments by flame, corona, plasmas, photons, electron beams, ion beams, X-rays, and γ-rays. Plasma treatment is probably the most versatile surface treatment technique. Different types of gases such as argon, oxygen, nitrogen, fluorine, carbon dioxide, and water can produce the unique surface properties required by various applications. For example, oxygen-plasma treatment can increase the surface energy of polymers, whereas fluorine-plasma treatment can decrease the surface energy and improve the chemical inertness. Cross-linking at a polymer surface can be introduced by an inert-gas plasma. Modification by plasma treatment is usually confined to the top several hundred ångströms and does not affect the bulk properties. The main disadvantage of this technique is that it requires a vacuum system, which increases the cost of operation. Thin polymer films with unique chemical and physical properties are produced by plasma polymerization

  16. Bactericidal effects of plasma-modified surface chemistry of silicon nanograss

    NASA Astrophysics Data System (ADS)

    Ostrikov, Kola; Macgregor-Ramiasa, Melanie; Cavallaro, Alex; (Ken Ostrikov, Kostya; Vasilev, Krasimir

    2016-08-01

    The surface chemistry and topography of biomaterials regulate the adhesion and growth of microorganisms in ways that are still poorly understood. Silicon nanograss structures prepared via inductively coupled plasma etching were coated with plasma deposited nanometer-thin polymeric films to produce substrates with controlled topography and defined surface chemistry. The influence of surface properties on Staphylococcus aureus proliferation is demonstrated and explained in terms of nanograss substrate wetting behaviour. With the combination of the nanograss topography; hydrophilic plasma polymer coatings enhanced antimicrobial activity while hydrophobic coatings reduced it. This study advances the understanding of the effects of surface wettability on the bactericidal properties of reactive nano-engineered surfaces.

  17. Surface Modification of Commercial Low-Carbon Steel using Glow Discharge Nitrogen Plasma and its Characterization

    NASA Astrophysics Data System (ADS)

    Srikanth, S.; Saravanan, P.; Joseph, Alphonsa; Ravi, K.

    2013-09-01

    Plasma nitriding under glow discharge nitrogen plasma has been undertaken on laboratory scale for surface engineering of commercial low carbon steels. The treatment has been shown to confer exceptional improvement in surface properties, viz., hardness and corrosion resistance. The results have been discussed in light of microstructural changes occurring on steel surface and its interior as a result of Fickian nitrogen diffusion and correlated with influences of nitriding-temperature and alloying elements (Mn, Nb, and Si) in steel.

  18. Metal surface nitriding by laser induced plasma

    NASA Astrophysics Data System (ADS)

    Thomann, A. L.; Boulmer-Leborgne, C.; Andreazza-Vignolle, C.; Andreazza, P.; Hermann, J.; Blondiaux, G.

    1996-10-01

    We study a nitriding technique of metals by means of laser induced plasma. The synthesized layers are composed of a nitrogen concentration gradient over several μm depth, and are expected to be useful for tribological applications with no adhesion problem. The nitriding method is tested on the synthesis of titanium nitride which is a well-known compound, obtained at present by many deposition and diffusion techniques. In the method of interest, a laser beam is focused on a titanium target in a nitrogen atmosphere, leading to the creation of a plasma over the metal surface. In order to understand the layer formation, it is necessary to characterize the plasma as well as the surface that it has been in contact with. Progressive nitrogen incorporation in the titanium lattice and TiN synthesis are studied by characterizing samples prepared with increasing laser shot number (100-4000). The role of the laser wavelength is also inspected by comparing layers obtained with two kinds of pulsed lasers: a transversal-excited-atmospheric-pressure-CO2 laser (λ=10.6 μm) and a XeCl excimer laser (λ=308 nm). Simulations of the target temperature rise under laser irradiation are performed, which evidence differences in the initial laser/material interaction (material heated thickness, heating time duration, etc.) depending on the laser features (wavelength and pulse time duration). Results from plasma characterization also point out that the plasma composition and propagation mode depend on the laser wavelength. Correlation of these results with those obtained from layer analyses shows at first the important role played by the plasma in the nitrogen incorporation. Its presence is necessary and allows N2 dissociation and a better energy coupling with the target. Second, it appears that the nitrogen diffusion governs the nitriding process. The study of the metal nitriding efficiency, depending on the laser used, allows us to explain the differences observed in the layer features

  19. Plasma-Surface Interactions in Electric Thrusters

    NASA Astrophysics Data System (ADS)

    Goebel, Dan

    2013-09-01

    Of critical importance in electric propulsion missions in space is thruster life, which is determined to a large extent by wall erosion from plasma-materials interactions. While the plasmas generated in different thrusters vary, the particle fluxes, energies and temperatures in contact with the walls are somewhat similar. The erosion rates are then determined by details of materials, incident angles, etc. In ion and Hall thrusters commonly used today, for example, cathode life is determined by low energy (<=100 eV) Xe ion erosion of the cathode electrodes. Erosion of ion thruster accelerator grids is dominated by charge exchange ion bombardment with energies of 200 to 400 V. The incident angle of these ions is near normal, but the sputtered particles are ejected with a butterfly distribution that directs particles along the thruster axis and causes build up of material on the upstream and downstream surfaces. In Hall thrusters, the plasma materials interactions at the wall are complicated because the walls are typically ceramic and selected for a low secondary electron yield for thruster performance. The erosion rates at the wall vary due to non-uniform plasma contact with the surface causing grooves and surface changes. These effects will be discussed for various thrusters.

  20. Role of surface temperature in fluorocarbon plasma-surface interactions

    SciTech Connect

    Nelson, Caleb T.; Overzet, Lawrence J.; Goeckner, Matthew J.

    2012-07-15

    This article examines plasma-surface reaction channels and the effect of surface temperature on the magnitude of those channels. Neutral species CF{sub 4}, C{sub 2}F{sub 6}, and C{sub 3}F{sub 8} are produced on surfaces. The magnitude of the production channel increases with surface temperature for all species, but favors higher mass species as the temperature is elevated. Additionally, the production rate of CF{sub 2} increases by a factor of 5 as the surface temperature is raised from 25 Degree-Sign C to 200 Degree-Sign C. Fluorine density, on the other hand, does not change as a function of either surface temperature or position outside of the plasma glow. This indicates that fluorine addition in the gas-phase is not a dominant reaction. Heating reactors can result in higher densities of depositing radical species, resulting in increased deposition rates on cooled substrates. Finally, the sticking probability of the depositing free radical species does not change as a function of surface temperature. Instead, the surface temperature acts together with an etchant species (possibly fluorine) to elevate desorption rates on that surface at temperatures lower than those required for unassisted thermal desorption.

  1. Lightweight Portable Plasma Medical Device - Plasma Engineering Research Laboratory

    DTIC Science & Technology

    2014-10-01

    poultry , eggs, tomato and papaya using non-thermal plasma. (Corpus Christi, TX: Sigma Xi 12th Annual Undergraduate Research Symposium, 2013). 100...Guadalupe Vidal, Kim Pham, Magesh Thiyagarajan. Effective deactivation of Bacillus cereus and Salmonella Typhimurium in chicken poultry , eggs, tomato and...Typhimurium in chicken poultry , eggs, tomato and papaya using non-thermal plasma. (Corpus Christi, TX: Sigma Xi 12th Annual Undergraduate Research

  2. Magnetic surface topology in decaying plasma knots

    NASA Astrophysics Data System (ADS)

    Smiet, C. B.; Thompson, A.; Bouwmeester, P.; Bouwmeester, D.

    2017-02-01

    Torus-knot solitons have recently been formulated as solutions to the ideal incompressible magnetohydrodynamics (MHD) equations. We investigate numerically how these fields evolve in resistive, compressible, and viscous MHD. We find that certain decaying plasma torus knots exhibit magnetic surfaces that are topologically distinct from a torus. The evolution is predominantly determined by a persistent zero line in the field present when the poloidal winding number {n}{{p}}\

  3. Investigation of plasma-surface interaction at plasma beam facilities

    NASA Astrophysics Data System (ADS)

    Kurnaev, V.; Vizgalov, I.; Gutorov, K.; Tulenbergenov, T.; Sokolov, I.; Kolodeshnikov, A.; Ignashev, V.; Zuev, V.; Bogomolova, I.; Klimov, N.

    2015-08-01

    The new Plasma Beam Facility (PBF) has been put into operation for assistance in testing of plasma faced components at Material Science Kazakhstan Tokamak (KTM). PBF includes a powerful electron gun (up to 30 kV, 1 A) and a high vacuum chamber with longitudinal magnetic field coils (up to 0.2 T). The regime of high vacuum electron beam transportation is used for thermal tests with power density at the target surface up to 10 GW/m2. The beam plasma discharge (BPD) regime with a gas-puff is used for generation of intensive ion fluxes up to 3 ṡ 1022 m-2 s-1. Initial tests of the KTM PBF's capabilities were carried out: various discharge regimes, carbon deposits cleaning, simultaneous thermal and ion impacts on radiation cooled refractory targets. With a water-cooled target the KTM PBF could be used for high heat flux tests of materials (validated by the experiment with W mock-up at the PR-2 PBF).

  4. Fundamental aspects in the plasma surface interaction during plasma sterilization

    NASA Astrophysics Data System (ADS)

    von Keudell, A.

    2008-07-01

    The inactivation of bacteria in oxygen or hydrogen containing low pressure plasmas is investigated by mimicking the plasma exposure with a dedicated beam experiment employing argon ions, oxygen molecules/atoms and hydrogen atoms . Thereby, fundamental inactivation mechanisms can be revealed. It is shown that the impact of O atoms or H atoms has no effect on the viability of bacterial spores and that no etching of the spore coat occurs up to an O and H atom fluence of 3.5 x 10^19 cm^-2. The impact of argon ions with an energy of 200 eV does not cause significant erosion for fluences up to 1.15 x 10^18 cm^-2. However, the combined impact of argon ions and oxygen molecules/atoms or H atoms causes significant etching of the spores and significant inactivation. This is explained by the process of chemical sputtering, where an ion induced defect at the surface of the spore reacts with either the incident bi-radical O_2 or with an incident O atom or H atom. This leads to the formation of CO, CO_2 and H_2O and thus to erosion. This beam results are compared to a broad sterilization campaign using an ICP reactor in a European round robin experiment BIODECON. Strategies for optimizing the plasma sterilization processes will be presented.

  5. Plasma diagnostics and plasma-surface interactions in inductively coupled plasmas

    NASA Astrophysics Data System (ADS)

    Titus, Monica Joy

    The semiconductor industry's continued trend of manufacturing device features on the nanometer scale requires increased plasma processing control and improved understanding of plasma characteristics and plasma-surface interactions. This dissertation presents a series of experimental results for focus studies conducted in an inductively coupled plasma (ICP) system. First novel "on-wafer" diagnostic tools are characterized and related to plasma characteristics. Second, plasma-polymer interactions are characterized as a function of plasma species and processing parameters. Complementary simulations accompany each focus study to supplement experimental findings. Wafer heating mechanisms in inductively coupled molecular gas plasmas are explored with PlasmaTemp(TM), a novel "on-wafer" diagnostic tool. Experimental wafer measurements are obtained with the PlasmaTemp(TM) wafer processed in argon (Ar) and argon-oxygen (Ar/O2) mixed plasmas. Wafer heating mechanisms were determined by combining the experimental measurements with a 3-dimensional heat transfer model of the wafer. Comparisons between pure Ar and Ar/O2 plasmas demonstrate that two additional wafer heating mechanisms can be important in molecular gas plasmas compared to atomic gas discharges. Thermal heat conduction from the neutral gas and O-atom recombination on wafer surface can contribute as much as 60% to wafer heating under conditions of low-energy ion bombardment in molecular plasmas. Measurements of a second novel "on-wafer" diagnostic sensor, the PlasmaVolt(TM), were tested and validated in the ICP system for Ar plasmas varying in power and pressure. Sensor measurements were interpreted with a numerical sheath simulation and comparison to scaling laws derived from the inhomogeneous sheath model. The study demonstrates sensor measurements are proportional to the RF-current through the sheath and the scaling is a function of sheath impedance. PlasmaVolt(TM) sensor measurements are proportional to the

  6. Plasma technology for increase of operating high pressure fuel pump diesel engines

    NASA Astrophysics Data System (ADS)

    Solovev, R. Y.; Sharifullin, S. N.; Adigamov, N. R.

    2016-01-01

    This paper presents the results of a change in the service life of high pressure fuel pumps of diesel engines on the working surface of the plunger which a wear resistant dielectric plasma coatings based on silicon oxycarbonitride. Such coatings possess high wear resistance, chemical inertness and low friction.

  7. Characterisation of nanomaterial hydrophobicity using engineered surfaces

    NASA Astrophysics Data System (ADS)

    Desmet, Cloé; Valsesia, Andrea; Oddo, Arianna; Ceccone, Giacomo; Spampinato, Valentina; Rossi, François; Colpo, Pascal

    2017-03-01

    Characterisation of engineered nanomaterials (NMs) is of outmost importance for the assessment of the potential risks arising from their extensive use. NMs display indeed a large variety of physico-chemical properties that drastically affect their interaction with biological systems. Among them, hydrophobicity is an important property that is nevertheless only slightly covered by the current physico-chemical characterisation techniques. In this work, we developed a method for the direct characterisation of NM hydrophobicity. The determination of the nanomaterial hydrophobic character is carried out by the direct measurement of the affinity of the NMs for different collectors. Each collector is an engineered surface designed in order to present specific surface charge and hydrophobicity degrees. Being thus characterised by a combination of surface energy components, the collectors enable the NM immobilisation with surface coverage in relation to their hydrophobicity. The experimental results are explained by using the extended DLVO theory, which takes into account the hydrophobic forces acting between NMs and collectors.

  8. [Effect of radio frequency discharge plasma on surface properties and biocompatibility of polycaprolactone matrices].

    PubMed

    Bolbasov, E N; Antonova, L V; Matveeva, V G; Novikov, V A; Shesterikov, E V; Bogomolova, N L; Golovkin, A S; Tverdohlebov, S I; Barbarash, O L; Barbarash, L S

    2016-01-01

    Surface modification of bioresorbable polymer material (polycaprolactone, PCL) with abnormal glow discharge, initiated during radio-frequency magnetron sputtering of a hydroxyapatite target was investigated. Plasma treatment resulted in an increase of surface roughness of PCL, crystallite size, the surface free energy and hydrophilicity. Increased treatment time (30, 60, 150 seconds) provoked the polymer surface saturation with the sputtering target ions (calcium, phosphorus). The assessment of plasma exposure of PCL surface on bone marrow multipotent mesenchymal stromal cells behavior (BM MSCs) has been performed. Modification of the polymer surface with the abnormal glow discharge stimulated adhesion and subsequent proliferation of BM MSCs; thus, maximum values were achieved with the surface treatment for 60 s. This type of plasma modification did not affect cell viability (apoptosis, necrosis). Thus, the surface modification with abnormal glow discharge, initiated during radio-frequency magnetron sputtering of a hydroxyapatite target, appear to be a promising method of surface modification of bioresorbable polymer material (PCL) for tissue engineering.

  9. Laser ignition of plasma off aluminum surfaces

    NASA Astrophysics Data System (ADS)

    Weyl, G.; Pirri, A.; Root, R.

    1980-07-01

    The prompt initiation of a plasma above metal surfaces irradiated by a CO2 laser pulse in the intensities range one million to one billion W per sq cm is modelled. The initiation mechanism is assumed to be the vaporization of flakes or surface defects that are thermally insulated from the bulk surface, followed by laser induced breakdown in the vapor. The fluid dynamics of the expansion in an air background is modelled in the 1 dimensional and 3 dimensional regimes. Breakdown of the vapor due to inverse bremsstrahlung absorption of the laser radiation is calculated specifically for aluminum by use of a Boltzmann code. Results are presented in the form of a map of breakdown time versus incident laser flux and compared with available experimental data.

  10. Platelet rich plasma in ocular surface.

    PubMed

    Riestra, A C; Alonso-Herreros, J M; Merayo-Lloves, J

    2016-10-01

    The use of platelet-rich preparations has experienced a significant increase in recent years due to its role in tissue-repair and regeneration. The aim of this study is to examine the available evidence regarding the application of plasma rich in growth factors, and its variations, on the ocular surface. A review is also presented on the effects of platelet-derived growth factors, the implications of the preparation methods, and the existing literature on the safety and efficacy of these therapies in ocular surface diseases. Despite the widespread use of platelet preparations there is no consensus on the most appropriate preparation method, and growth factors concentration vary with different systems. These preparations have been used in the treatment of ocular surface diseases, such as dry eye or persistent epithelial defects, among others, with good safety and efficacy profiles, but further studies are needed to compare to the currently available alternatives.

  11. Light Weight Portable Plasma Medical Device - Plasma Engineering Research Laboratory

    DTIC Science & Technology

    2011-10-01

    acting on the objective lens. Great care was taken to position the objective lens together with the plasma chamber precisely in the line of sight...pressure as that of the chamber pressure in order to avoid differential pressures acting on the objective lens. Great care was taken to position the...Mohid, in Experimental micromachining of silicon with Nd-YAG laser, Malaysia , 2011 (Trans Tech Publications), p. 244. 5 P. G. Ashmore, Photochemistry

  12. Lightweight Portable Plasma Medical Device - Plasma Engineering Research Laboratory

    DTIC Science & Technology

    2012-10-01

    oxides (NOx) are produced through N2 and O2 reactions [62, 63]. The production of NOx species is mainly dependent on the oxygen (O2) concentration...Federal, $812,594.00. Thiyagarajan, Magesh (Principal), "Plasma Assisted Microbial Decontamination for Food Product Processing Industries...processes and products including processing and preservation of food items such as 86 vegetables, fruits and packaged foods , medical devices and

  13. Two surface plasmon decay of plasma oscillations

    SciTech Connect

    Kluge, T. Metzkes, J.; Zeil, K.; Bussmann, M.; Schramm, U.; Cowan, T. E.

    2015-06-15

    The interaction of ultra-intense lasers with solid foils can be used to accelerate ions to high energies well exceeding 60 MeV [Gaillard et al., Phys. Plasmas 18, 056710 (2011)]. The non-linear relativistic motion of electrons in the intense laser radiation leads to their acceleration and later to the acceleration of ions. Ions can be accelerated from the front surface, the foil interior region, and the foil rear surface (target normal sheath acceleration (TNSA), most widely used), or the foil may be accelerated as a whole if sufficiently thin (radiation pressure acceleration). Here, we focus on the most widely used mechanism for laser ion-acceleration of TNSA. Starting from perfectly flat foils, we show by simulations how electron filamentation at or inside the solid leads to spatial modulations in the ions. The exact dynamics depend very sensitively on the chosen initial parameters which has a tremendous effect on electron dynamics. In the case of step-like density gradients, we find evidence that suggests a two-surface-plasmon decay of plasma oscillations triggering a Raileigh-Taylor-like instability.

  14. Modification of Aerodynamic Surfaces Using Plasma

    DTIC Science & Technology

    2005-07-01

    slading discharge (Task 3) ……………………………………………………………………..…………...35 § 2.1. Development of discharge physical model. General properties of sliding discharge...be called for solution of plasma aerodynamic problems. A sliding discharge possess a number of unique properties (simplicity of realization...investigation of sub-layer material effect on the discharge properties . 6. Test experiments on sliding discharge’s forming at a curvilinear surface

  15. Vacuum plasma spray applications on liquid fuel rocket engines

    NASA Astrophysics Data System (ADS)

    McKechnie, T. N.; Zimmerman, F. R.; Bryant, M. A.

    1992-07-01

    The vacuum plasma spray process (VPS) has been developed by NASA and Rocketdyne for a variety of applications on liquid fuel rocket engines, including the Space Shuttle Main Engine. These applications encompass thermal barrier coatings which are thermal shock resistant for turbopump blades and nozzles; bond coatings for cryogenic titanium components; wear resistant coatings and materials; high conductivity copper, NaRloy-Z, combustion chamber liners, and structural nickel base material, Inconel 718, for nozzle and combustion chamber support jackets.

  16. Control of surface wettability via strain engineering

    NASA Astrophysics Data System (ADS)

    Xiong, Wei; Liu, Jefferson Zhe; Zhang, Zhi-Liang; Zhen, Quan-Shui

    2013-08-01

    Reversible control of surface wettability has wide applications in lab-on-chip systems, tunable optical lenses, and microfluidic tools. Using a graphene sheet as a sample material and molecular dynamic simulations, we demonstrate that strain engineering can serve as an effective way to control the surface wettability. The contact angles θ of water droplets on a graphene vary from 72.5° to 106° under biaxial strains ranging from -10% to 10% that are applied on the graphene layer. For an intrinsic hydrophilic surface (at zero strain), the variation of θ upon the applied strains is more sensitive, i.e., from 0° to 74.8°. Overall the cosines of the contact angles exhibit a linear relation with respect to the strains. In light of the inherent dependence of the contact angle on liquid-solid interfacial energy, we develop an analytic model to show the cos θ as a linear function of the adsorption energy E ads of a single water molecule over the substrate surface. This model agrees with our molecular dynamic results very well. Together with the linear dependence of E ads on biaxial strains, we can thus understand the effect of strains on the surface wettability. Thanks to the ease of reversibly applying mechanical strains in micro/nano-electromechanical systems, we believe that strain engineering can be a promising means to achieve the reversibly control of surface wettability.

  17. Nonlinear Cylindrical Waves on a Plane Plasma Surface

    NASA Astrophysics Data System (ADS)

    Gradov, O. M.

    2004-01-01

    By means of the cold electron plasma equations, it is shown that surface soliton solutions can exist in the azimuthally symmetric case at the boundary of semi-infinite plasmas for both standing and running waves.

  18. Advancing Sustainable Surface Engineering: Challenges & Future Opportunities

    DTIC Science & Technology

    2014-11-01

    2013 Noblis , Inc. Advancing Sustainable Surface Engineering: Challenges & Future Opportunities Dr. Jeffrey Marqusee Chief Scientist...NUMBER 5e. TASK NUMBER 5f. WORK UNIT NUMBER 7. PERFORMING ORGANIZATION NAME(S) AND ADDRESS(ES) Noblis Inc,3150 Fairview Park Drive,Falls Church,VA...unclassified b. ABSTRACT unclassified c. THIS PAGE unclassified Standard Form 298 (Rev. 8-98) Prescribed by ANSI Std Z39-18 2 © 2013 Noblis , Inc

  19. Metastable states of plasma particles close to a charged surface

    SciTech Connect

    Shavlov, A. V.; Dzhumandzhi, V. A.

    2015-09-15

    The free energy of the plasma particles and the charged surface that form an electroneutral system is calculated on the basis of the Poisson-Boltzmann equation. It is shown that, owing to correlation of light plasma particles near the charged surface and close to heavy particles of high charge, there can be metastable states in plasma. The corresponding phase charts of metastable states of the separate components of plasma, and plasma as a whole, are constructed. These charts depend on temperature, the charge magnitude, the size of the particles, and the share of the charge of the light carriers out of the total charge of the plasma particles.

  20. Plasma-Surface Interactions and RF Antennas

    NASA Astrophysics Data System (ADS)

    Jenkins, Thomas; Smithe, D. N.; Beckwith, K.; Davidson, B. D.; Kruger, S. E.; Pankin, A. Y.; Roark, C. M.

    2015-11-01

    Implementation of recently developed finite-difference time-domain (FDTD) modeling techniques on high-performance computing platforms allows RF power flow, and antenna near- and far-field behavior, to be studied in realistic experimental ion-cyclotron resonance heating scenarios at previously inaccessible levels of resolution. We present results and 3D animations of high-performance (10k-100k core) FDTD simulations of Alcator C-Mod's field-aligned ICRF antenna on the Titan supercomputer, considering (a) the physics of slow wave excitation in the immediate vicinity of the antenna hardware and in the scrape-off layer for various edge densities, and (b) sputtering and impurity production, as driven by self-consistent sheath potentials at antenna surfaces. Related research efforts in low-temperature plasma modeling, including the use of proper orthogonal decomposition methods for PIC/fluid modeling and the development of plasma chemistry tools (e.g. a robust and flexible reaction database, principal path reduction analysis capabilities, and improved visualization options), will also be summarized. Supported by U.S. DoE SBIR Phase I/II Award DE-SC0009501 and ALCC/OLCF.

  1. Engineering microbial surfaces to degrade lignocellulosic biomass

    PubMed Central

    Huang, Grace L; Anderson, Timothy D; Clubb, Robert T

    2014-01-01

    Renewable lignocellulosic plant biomass is a promising feedstock from which to produce biofuels, chemicals, and materials. One approach to cost-effectively exploit this resource is to use consolidating bioprocessing (CBP) microbes that directly convert lignocellulose into valuable end products. Because many promising CBP-enabling microbes are non-cellulolytic, recent work has sought to engineer them to display multi-cellulase containing minicellulosomes that hydrolyze biomass more efficiently than isolated enzymes. In this review, we discuss progress in engineering the surfaces of the model microorganisms: Bacillus subtilis, Escherichia coli, and Saccharomyces cerevisiae. We compare the distinct approaches used to display cellulases and minicellulosomes, as well as their surface enzyme densities and cellulolytic activities. Thus far, minicellulosomes have only been grafted onto the surfaces of B. subtilis and S. cerevisiae, suggesting that the absence of an outer membrane in fungi and Gram-positive bacteria may make their surfaces better suited for displaying the elaborate multi-enzyme complexes needed to efficiently degrade lignocellulose. PMID:24430239

  2. Surface wave and linear operating mode of a plasma antenna

    SciTech Connect

    Bogachev, N. N. Bogdankevich, I. L.; Gusein-zade, N. G.; Rukhadze, A. A.

    2015-10-15

    The relation between the propagation conditions of a surface electromagnetic wave along a finiteradius plasma cylinder and the linear operating mode of a plasma antenna is investigated. The solution to the dispersion relation for a surface wave propagating along a finite-radius plasma cylinder is analyzed for weakly and strongly collisional plasmas. Computer simulations of an asymmetrical plasma dipole antenna are performed using the KARAT code, wherein the dielectric properties of plasma are described in terms of the Drude model. The plasma parameters corresponding to the linear operating mode of a plasma antenna are determined. It is demonstrated that the characteristics of the plasma antenna in this mode are close to those of an analogous metal antenna.

  3. Atomically Precise Surface Engineering for Producing Imagers

    NASA Technical Reports Server (NTRS)

    Greer, Frank (Inventor); Jones, Todd J. (Inventor); Nikzad, Shouleh (Inventor); Hoenk, Michael E. (Inventor)

    2015-01-01

    High-quality surface coatings, and techniques combining the atomic precision of molecular beam epitaxy and atomic layer deposition, to fabricate such high-quality surface coatings are provided. The coatings made in accordance with the techniques set forth by the invention are shown to be capable of forming silicon CCD detectors that demonstrate world record detector quantum efficiency (>50%) in the near and far ultraviolet (155 nm-300 nm). The surface engineering approaches used demonstrate the robustness of detector performance that is obtained by achieving atomic level precision at all steps in the coating fabrication process. As proof of concept, the characterization, materials, and exemplary devices produced are presented along with a comparison to other approaches.

  4. Plasma Propulsion Testing Capabilities at Arnold Engineering Development Center

    NASA Technical Reports Server (NTRS)

    Polzin, Kurt A.; Dawbarn, Albert; Moeller, Trevor

    2007-01-01

    This paper describes the results of a series of experiments aimed at quantifying the plasma propulsion testing capabilities of a 12-ft diameter vacuum facility (12V) at USAF-Arnold Engineering Development Center (AEDC). Vacuum is maintained in the 12V facility by cryogenic panels lining the interior of the chamber. The pumping capability of these panels was shown to be great enough to support plasma thrusters operating at input electrical power >20 kW. In addition, a series of plasma diagnostics inside the chamber allowed for measurement of plasma parameters at different spatial locations, providing information regarding the chamber's effect on the global plasma thruster flowfield. The plasma source used in this experiment was Hall thruster manufactured by Busek Co. The thruster was operated at up to 20 kW steady-state power in both a lower current and higher current mode. The vacuum level in the chamber never rose above 9 x 10(exp -6) torr during the course of testing. Langmuir probes, ion flux probes, and Faraday cups were used to quantify the plasma parameters in the chamber. We present the results of these measurements and estimates of pumping speed based on the background pressure level and thruster propellant mass flow rate.

  5. Characterization of surface hydrophobicity of engineered nanoparticles.

    PubMed

    Xiao, Yao; Wiesner, Mark R

    2012-05-15

    The surface chemistry of nanoparticles, including their hydrophobicity, is a key determinant of their fate, transport and toxicity. Engineered NPs often have surface coatings that control the surface chemistry of NPs and may dominate the effects of the nanoparticle core. Suitable characterization methods for surface hydrophobicity at the nano-scale are needed. Three types of methods, surface adsorption, affinity coefficient and contact angle, were investigated in this study with seven carbon and metal based NPs with and without coatings. The adsorption of hydrophobic molecules, Rose Bengal dye and naphthalene, on NPs was used as one measure of hydrophobicity and was compared with the relative affinity of NPs for octanol or water phases, analogous to the determination of octanol-water partition coefficients for organic molecules. The sessile drop method was adapted for measuring contact angle of a thin film of NPs. Results for these three methods were qualitatively in agreement. Aqueous-nC(60) and tetrahydrofuran-nC(60) were observed to be more hydrophobic than nano-Ag coated with polyvinylpyrrolidone or gum arabic, followed by nano-Ag or nano-Au with citrate-functionalized surfaces. Fullerol was shown to be the least hydrophobic of seven NPs tested. The advantages and limitations of each method were also discussed.

  6. Mathematical simulation of surface heating during plasma spraying

    NASA Astrophysics Data System (ADS)

    Bogdanovich, V. I.; Giorbelidze, M. G.

    2017-02-01

    A mathematical model of temperature distribution over the flat ‘coating-substrate’ system section during plasma spraying, taking into account a plasma gun travel and coating buildup has been developed. It has been shown that the temperature value in the near-surface layer of the sprayed coating during the plasma gun passage can significantly exceed the temperature values in underlayers.

  7. Nanocapillary Atmospheric Pressure Plasma Jet: A Tool for Ultrafine Maskless Surface Modification at Atmospheric Pressure.

    PubMed

    Motrescu, Iuliana; Nagatsu, Masaaki

    2016-05-18

    With respect to microsized surface functionalization techniques we proposed the use of a maskless, versatile, simple tool, represented by a nano- or microcapillary atmospheric pressure plasma jet for producing microsized controlled etching, chemical vapor deposition, and chemical modification patterns on polymeric surfaces. In this work we show the possibility of size-controlled surface amination, and we discuss it as a function of different processing parameters. Moreover, we prove the successful connection of labeled sugar chains on the functionalized microscale patterns, indicating the possibility to use ultrafine capillary atmospheric pressure plasma jets as versatile tools for biosensing, tissue engineering, and related biomedical applications.

  8. Engineered Multifunctional Surfaces for Fluid Handling

    NASA Technical Reports Server (NTRS)

    Thomas, Chris; Ma, Yonghui; Weislogel, Mark

    2012-01-01

    Designs incorporating variations in capillary geometry and hydrophilic and/or antibacterial surface properties have been developed that are capable of passive gas/liquid separation and passive water flow. These designs can incorporate capillary grooves and/or surfaces arranged to create linear and circumferential capillary geometry at the micro and macro scale, radial fin configurations, micro holes and patterns, and combinations of the above. The antibacterial property of this design inhibits the growth of bacteria or the development of biofilm. The hydrophilic property reduces the water contact angle with a treated substrate such that water spreads into a thin layer atop the treated surface. These antibacterial and hydrophilic properties applied to a thermally conductive surface, combined with capillary geometry, create a novel heat exchanger capable of condensing water from a humid, two-phase water and gas flow onto the treated heat exchanger surfaces, and passively separating the condensed water from the gas flow in a reduced gravity application. The overall process to generate the antibacterial and hydrophilic properties includes multiple steps to generate the two different surface properties, and can be divided into two major steps. Step 1 uses a magnetron-based sputtering technique to implant the silver atoms into the base material. A layer of silver is built up on top of the base material. Completion of this step provides the antibacterial property. Step 2 uses a cold-plasma technique to generate the hydrophilic surface property on top of the silver layer generated in Step 1. Completion of this step provides the hydrophilic property in addition to the antibacterial property. Thermally conductive materials are fabricated and then treated to create the antibacterial and hydrophilic surface properties. The individual parts are assembled to create a condensing heat exchanger with antibacterial and hydrophilic surface properties and capillary geometry, which is

  9. Surface electromagnetic wave equations in a warm magnetized quantum plasma

    SciTech Connect

    Li, Chunhua; Yang, Weihong; Wu, Zhengwei; Chu, Paul K.

    2014-07-15

    Based on the single-fluid plasma model, a theoretical investigation of surface electromagnetic waves in a warm quantum magnetized inhomogeneous plasma is presented. The surface electromagnetic waves are assumed to propagate on the plane between a vacuum and a warm quantum magnetized plasma. The quantum magnetohydrodynamic model includes quantum diffraction effect (Bohm potential), and quantum statistical pressure is used to derive the new dispersion relation of surface electromagnetic waves. And the general dispersion relation is analyzed in some special cases of interest. It is shown that surface plasma oscillations can be propagated due to quantum effects, and the propagation velocity is enhanced. Furthermore, the external magnetic field has a significant effect on surface wave's dispersion equation. Our work should be of a useful tool for investigating the physical characteristic of surface waves and physical properties of the bounded quantum plasmas.

  10. Effect of surface derived hydrocarbon impurities on Ar plasma properties

    SciTech Connect

    Fox-Lyon, Nick; Oehrlein, Gottlieb S.; Godyak, Valery

    2014-05-15

    The authors report on Langmuir probe measurements that show that hydrocarbon surfaces in contact with Ar plasma cause changes of electron energy distribution functions due to the flux of hydrogen and carbon atoms released by the surfaces. The authors compare the impact on plasma properties of hydrocarbon species gasified from an etching hydrocarbon surface with injection of gaseous hydrocarbons into Ar plasma. They find that both kinds of hydrocarbon injections decrease electron density and slightly increase electron temperatures of low pressure Ar plasma. For low percentages of impurities (∼1% impurity in Ar plasma explored here), surface-derived hydrocarbon species and gas phase injected hydrocarbon molecules cause similar changes of plasma properties for the same number of hydrocarbon molecules injected into Ar with a decrease in electron density of ∼4%.

  11. Engineering nanomaterial surfaces for biomedical applications.

    PubMed

    Wang, Xin; Liu, Li-Hong; Ramström, Olof; Yan, Mingdi

    2009-10-01

    Nanomaterials, possessing unique physical and chemical properties, have attracted much interest and generated wide varieties of applications. Recent investigations of functionalized nanomaterials have expanded into the biological area, providing a versatile platform in biomedical applications such as biomolecular sensing, biological imaging, drug delivery and disease therapy. Bio-functions and bio-compatibility of nanomaterials are realized by introducing synthetic ligands or natural biomolecules onto nanomaterials, and combining ligand-receptor biological interactions with intrinsic nanomaterial properties. Common strategies of engineering nanomaterial surfaces involve physisorption or chemisorption of desired ligands. We developed a photochemically initiated surface coupling chemistry, bringing versatility and simplicity to nanomaterial functionalization. The method was applied to attach underivatized carbohydrates efficiently on gold and iron oxide nanoparticles, and the resulting glyconanoparticles were successfully used as a sensitive biosensing system probing specific interactions between carbohydrates and proteins as well as bacteria.

  12. Engineering Nanomaterial Surfaces for Biomedical Applications

    PubMed Central

    Wang, Xin; Liu, Li-Hong; Ramström, Olof; Yan, Mingdi

    2014-01-01

    Nanomaterials, possessing unique physical and chemical properties, have attracted much interest and generated wide varieties of applications. Recent investigations of functionalized nanomaterials have expanded into the biological area, providing a versatile platform in biomedical applications such as biomolecular sensing, biological imaging, drug delivery and disease therapy. Bio-functions and bio-compatibility of nanomaterials are realized by introducing synthetic ligands or natural biomolecules onto nanomaterials, and combining ligand-receptor biological interactions with intrinsic nanomaterial properties. Common strategies of engineering nanomaterial surfaces involve physisorption or chemisorption of desired ligands. We developed a photochemically initiated surface coupling chemistry, bringing versatility and simplicity to nanomaterial functionalization. The method was applied to attach underivatized carbohydrates efficiently on gold and iron oxide nanoparticles, and the resulting glyconanoparticles were successfully used as a sensitive biosensing system probing specific interactions between carbohydrates and proteins as well as bacteria. PMID:19596820

  13. Plasma technologies application for building materials surface modification

    NASA Astrophysics Data System (ADS)

    Volokitin, G. G.; Skripnikova, N. K.; Volokitin, O. G.; Shehovtzov, V. V.; Luchkin, A. G.; Kashapov, N. F.

    2016-01-01

    Low temperature arc plasma was used to process building surface materials, such as silicate brick, sand lime brick, concrete and wood. It was shown that building surface materials modification with low temperature plasma positively affects frost resistance, water permeability and chemical resistance with high adhesion strength. Short time plasma processing is rather economical than traditional processing thermic methods. Plasma processing makes wood surface uniquely waterproof and gives high operational properties, dimensional and geometrical stability. It also increases compression resistance and decreases inner tensions level in material.

  14. Application of a Plasma Powder Welding to engine valves

    SciTech Connect

    Takeuchi, Y.; Nagata, M.

    1985-01-01

    In hardfacing of automobile engine valves made of heat resisting steel such as 21-4N, conventional oxy-acetylene gase welding has been currently conducted manually by well trained operators because of using cast Stellite rods as the filler. In accordance with the strong demands of automatic welding, the authors newly developed an automatically controlled Plasma Powder Welding (PPW) system. This system is characterized by the application of a high thermal density plasma arc as heat source and by using power filler which melts more easily than bar cast rods. Moreover, this PPW system has been applied to the automotive engine valve production line and resulted in the great contribution to manpower saving.

  15. Plasma technologies application for building materials surface modification

    NASA Astrophysics Data System (ADS)

    Luchkin, A. G.; Hakki, A.; Rahimov, N. F.; Sadikov, K. G.; Luchkin, G. S.

    2017-01-01

    Low-temperature plasma modification of LiYF4 crystal surface in Helium atmosphere caused microhardness decreasing and increasing of roughness of crystal surface. The change of microhardness and morphology is a possible result of Fluorine outgoing from material structure due to heating of surface and plasma chemical reactions and ingoing of Oxygen. As a result of exchange and diffusion processes crystal surface structure become more crumbly, its morphology and mechanical properties change.

  16. Plasma Assisted Combustion: Fundamental Studies and Engine Applications

    NASA Astrophysics Data System (ADS)

    Lefkowitz, Joseph K.

    Successful and efficient ignition in short residence time environments or ultra-lean mixtures is a key technological challenge for the evolution of advanced combustion devices in terms of both performance and efficiency. To meet this challenge, interest in plasma assisted combustion (PAC) has expanded over the past 20 years. However, understanding of the underlying physical processes of ignition by plasma discharge remains elementary. In order to shed light on the key processes involved, two main thrusts of research were undertaken in this dissertation. First, demonstration of the applicability of plasma discharges in engines and engine-like environments was carried out using a microwave discharge and a nanosecond repetitively pulsed discharge in an internal combustion engine and a pulsed detonation engine, respectively. Major conclusions include the extension of lean ignition limits for both engines, significant reduction of ignition time for mixtures with large minimum ignition energy, and the discovery of the inter-pulse coupling effect of nanosecond repetitively pulsed (NRP) discharges at high frequency. In order to understand the kinetic processes that led to these improvements, the second thrust of research directly explored the chemical kinetic processes of plasma discharges with hydrocarbon fuels. For this purpose, a low pressure flow reactor with a NRP dielectric barrier discharge cell was assembled. The discharge cell was fitted with a Herriott type multipass mirror arrangement, which allowed quantitative laser absorption spectroscopy to be performed in situ during the plasma discharge. Experiments on methane and ethylene mixtures with oxygen, argon, and helium revealed the importance of low temperature oxidation pathways in PAC. In particular, oxygen addition reactions were shown to be of primary importance in the oxidation of these small hydrocarbons in the temperature range of 300-600 K. Kinetic modeling tools, including both a coupled plasma and

  17. Transient Plasma Ignition for Small Internal Combustion Engines

    DTIC Science & Technology

    2013-02-01

    Engines Gundersen, M . and Romney , P. University of Southern California FEBRUARY 2013 Final Report DISTRIBUTION A: Approved for public...so that heat release and combustion efficiency can be measured. References 1. Cathey, C., T. Tang, T. Shiraishi, T. Urushihara, A. Kuthi, and M . A...1, 1664-1668. 2. J.B. Liu, F. Wang, G. Li, A. Kuthi, E . J. Gutmark, P.D. Ronney, and M.A. Gundersen, “Transient Plasma Ignition,” IEEE

  18. Solitary surface-charge propagation along a plasma boundary

    NASA Astrophysics Data System (ADS)

    Stenflo, L.; Gradov, O. M.

    1984-09-01

    The nonlinear properties of long-wavelength ion acoustic surface modes in a semi-infinite plasma are studied. It is shown that finite-amplitude surface-charge layers can propagate along the plasma boundary with a velocity that exceeds the ion sound speed by a small term which is proportional to the squared inverse width of the solitary layer.

  19. Near-Surface Engineered Environmental Barrier Integrity

    SciTech Connect

    Piet, Steven James; Breckenridge, Robert Paul; Beller, John Michael; Geesey, Gill Gregroy; Glenn, David Frankie; Jacobson, Jacob Jordan; Martian, Pete; Matthern, Gretchen Elise; Mattson, Earl Douglas; Porro, Indrek; Southworth, Finis Hio; Steffler, Eric Darwin; Stormberg, Angelica Isabel; Stormberg, Gregory John; Versteeg, Roelof Jan; White, Gregory J

    2002-08-01

    The INEEL Environmental Systems Research and Analysis (ESRA) program has launched a new R&D project on Near-Surface Engineered Environmental Barrier Integrity to increase knowledge and capabilities for using engineering and ecological components to improve the integrity of near-surface barriers used to confine contaminants from the public and the environment. The knowledge gained and the capabilities built will help verify the adequacy of past remedial decisions and enable improved solutions for future cleanup decisions. The research is planned to (a) improve the knowledge of degradation mechanisms (weathering, biological, geological, chemical, radiological, and catastrophic) in times shorter than service life, (b) improve modeling of barrier degradation dynamics, (c) develop sensor systems to identify degradation prior to failure, and (d) provide a better basis for developing and testing of new barrier systems to increase reliability and reduce the risk of failure. Our project combines selected exploratory studies (benchtop and field scale), coupled effects accelerated aging testing and the meso-scale, testing of new monitoring concepts, and modeling of dynamic systems. The performance of evapo- transpiration, capillary, and grout-based barriers will be examined.

  20. Near-Surface Engineered Environmental Barrier Integrity

    SciTech Connect

    Piet, S.J.; Breckenridge, R.P.

    2002-05-15

    The INEEL Environmental Systems Research and Analysis (ESRA) program has launched a new R and D project on Near-Surface Engineered Environmental Barrier Integrity to increase knowledge and capabilities for using engineering and ecological components to improve the integrity of near-surface barriers used to confine contaminants from the public and the environment. The knowledge gained and the capabilities built will help verify the adequacy of past remedial decisions and enable improved solutions for future cleanup decisions. The research is planned to (a) improve the knowledge of degradation mechanisms (weathering, biological, geological, chemical, radiological, and catastrophic) in times shorter than service life, (b) improve modeling of barrier degradation dynamics, (c) develop sensor systems to identify degradation prior to failure, and (d) provide a better basis for developing and testing of new barrier systems to increase reliability and reduce the risk of failure. Our project combine s selected exploratory studies (benchtop and field scale), coupled effects accelerated aging testing and the meso-scale, testing of new monitoring concepts, and modeling of dynamic systems. The performance of evapo-transpiration, capillary, and grout-based barriers will be examined.

  1. Surface modification by argon plasma treatment improves antioxidant defense ability of CHO-k1 cells on titanium surfaces.

    PubMed

    de Queiroz, Jana Dara Freires; Leal, Angélica Maria de Sousa; Terada, Maysa; Agnez-Lima, Lucymara Fassarela; Costa, Isolda; Pinto, Nadja Cristhina de Souza; de Medeiros, Silvia Regina Batistuzzo

    2014-04-01

    Titanium is one of the most used materials in implants and changes in its surface can modify the cellular functional response to better implant fixation. An argon plasma treatment generates a surface with improved mechanical proprieties without modifying its chemical composition. Oxidative stress induced by biomaterials is considered one of the major causes of implant failure and studies in this field are fundamental to evaluate the biocompatibility of a new material. Therefore, in this work, induction of oxidative stress by titanium surfaces subjected to plasma treatment (PTTS) was evaluated. The viability of CHO-k1 cells was higher on PTTS discs. Cells grown on titanium surfaces are subjected to intracellular oxidative stress. Titanium discs subjected to the plasma treatment induced less oxidative stress than the untreated ones, which resulted in improved cellular survival. These were associated with improved cellular antioxidant response in Plasma Treated Titanium Surface (PTTS). Furthermore, a decrease in protein and DNA oxidative damage was observed on cells grown on the roughed surface when compared to the smooth one. In conclusion, our data suggest that the treatment of titanium with argon plasma may improve its biocompatible, thus improving its performance as implants or as a scaffold in tissue engineering.

  2. Experimentally Determined Plasma Parameters in a 30 cm Ion Engine

    NASA Technical Reports Server (NTRS)

    Sengupta, Anita; Goebel, Dan; Fitzgerald, Dennis; Owens, Al; Tynan, George; Dorner, Russ

    2004-01-01

    Single planar Langmuir probes and fiber optic probes are used to concurrently measure the plasma properties and neutral density variation in a 30cm diameter ion engine discharge chamber, from the immediate vicinity of the keeper to the near grid plasma region. The fiber optic probe consists of a collimated optical fiber recessed into a double bore ceramic tube fitted with a stainless steel light-limiting window. The optical fiber probe is used to measure the emission intensity of excited neutral xenon for a small volume of plasma, at various radial and axial locations. The single Langmuir probes, are used to generate current-voltage characteristics at a total of 140 spatial locations inside the discharge chamber. Assuming a maxwellian distribution for the electron population, the Langmuir probe traces provide spatially resolved measurements of plasma potential, electron temperature, and plasma density. Data reduction for the NSTAR TH8 and TH15 throttle points indicates an electron temperature range of 1 to 7.9 eV and an electron density range of 4e10 to le13 cm(sup -3), throughout the discharge chamber, consistent with the results in the literature. Plasma potential estimates, computed from the first derivative of the probe characteristic, indicate potential from 0.5V to 11V above the discharge voltage along the thruster centerline. These values are believed to be excessively high due to the sampling of the primary electron population along the thruster centerline. Relative neutral density profiles are also obtained with a fiber optic probe sampling photon flux from the 823.1 nm excited to ground state transition. Plasma parameter measurements and neutral density profiles will be presented as a function of probe location and engine discharge conditions. A discussion of the measured electron energy distribution function will also be presented, with regards to variation from pure maxwellian. It has been found that there is a distinct primary population found along

  3. Excimer laser induced plasma for aluminum alloys surface carburizing

    NASA Astrophysics Data System (ADS)

    Fariaut, F.; Boulmer-Leborgne, C.; Le Menn, E.; Sauvage, T.; Andreazza-Vignolle, C.; Andreazza, P.; Langlade, C.

    2002-01-01

    Currently, while light alloys are useful for automotive industries, their weak wear behavior is a limiting factor. The excimer laser carburizing process reported here has been developed to enhance the mechanical and chemical properties of aluminum alloys. An excimer laser beam is focused onto the alloy surface in a cell containing 1 bar methane or/and propylene gas. A vapor plasma expands from the surface, the induced shock wave dissociates and ionizes the ambient gas. Carbon atoms diffuse into the plasma in contact with the irradiated surface. An aluminum carbide layer is created by carbon diffusion in the surface liquid layer during the recombination phase of the plasma.

  4. Heating effects on modifying carbon surface by reactive plasma

    NASA Astrophysics Data System (ADS)

    Izumi, Yori; Katoh, Masaaki; Ohte, Takeo; Ohtani, Sugio; Kojima, Akira; Saitoh, Naoya

    1996-07-01

    In the surface modification by plasma, surface properties changes with time after the plasma treatment. Such changes should be avoided for practical application. Glassy carbon (GC) was subjected to simultaneous plasma and heat treatments in order to investigate the respective effects. Source gases were tetrafluoromethane (CF 4) and oxygen (O 2). Treatment time and heating temperature of the GC plate were 30 min and 200-500°C, respectively. The surface properties before and after plasma treatment were studied with contact angle measurements and ESCA. When the GC was heated at 400°C during CF 4 plasma treatment, the contact angle after plasma treatment was 133° and constant even after 24 h. At 500°C during O 2 plasma treatment, the contact angle after plasma treatment was 0° and constant even after 24 h. It is found that heating carbon surface during CF 4 or O 2 plasma treatment is effective to stop the change with time after plasma treatment.

  5. Surface cleaning of metal wire by atmospheric pressure plasma

    NASA Astrophysics Data System (ADS)

    Nakamura, T.; Buttapeng, C.; Furuya, S.; Harada, N.

    2009-11-01

    In this study, the possible application of atmospheric pressure dielectric barrier discharge plasma for the annealing of metallic wire is examined and presented. The main purpose of the current study is to examine the surface cleaning effect for a cylindrical object by atmospheric pressure plasma. The experimental setup consists of a gas tank, plasma reactor, and power supply with control panel. The gas assists in the generation of plasma. Copper wire was used as an experimental cylindrical object. This copper wire was irradiated with the plasma, and the cleaning effect was confirmed. The result showed that it is possible to remove the tarnish which exists on the copper wire surface. The experiment reveals that atmospheric pressure plasma is usable for the surface cleaning of metal wire. However, it is necessary to examine the method for preventing oxidization of the copper wire.

  6. Tritium trapping on the plasma irradiated tungsten surface

    SciTech Connect

    Torikai, Y.; Alimov, V.K.; Penzhorn, R.D.; Isobe, K.; Oyaidzu, M.; Yamanishi, T.; Ueda, Y.; Kurishita, H.; Philipps, V.; Kreter, A.; Zlobinski, M.

    2015-03-15

    Tungsten (W) is a candidate material for plasma-facing high heat-flux structures in future fusion reactors. The aim of this study is to assess how reasonably one can predict the tritium inventory in actual fusion machines using data on the hydrogen isotope inventory obtained in laboratory experiments. W specimens previously exposed to deuterium (D) plasmas both in the TEXTOR tokamak and high flux linear plasma generator (LPG) were subsequently loaded with tritium at 573 K for 3 h. The retention of tritium in the near-surface W layer was examined by imaging plate technique. The study shows that on the TEXTOR-plasma-exposed W surface, tritium was mainly trapped in carbon deposits, and for LPG-plasma-exposed W specimens, tritium was trapped in defects created in the near-surface layer during the course of D plasma exposure.

  7. Plasma modification of PMMA films: surface free energy and cell-attachment studies.

    PubMed

    Ozcan, Canturk; Hasirci, Nesrin

    2007-01-01

    The surface of a material is the most important part determining the acceptance by and compatibility with the environment. In many cases, although the bulk properties are excellent for a specific application, the surface may require to be modified and engineered in the desired direction. This is especially important for materials used in biological media, since the surface charge, hydophilicity and wettability are important for thrombosis formation, cell attachment or cell proliferation. In this study, poly(methyl methacrylate) films were prepared by solvent casting and their surfaces were modified by oxygen plasma treatment by applying powers of 20, 100 and 300 W. The effects of surface chemistry alterations on hydophilicity, work of adhesion, surface free energy and cell adhesion were examined. Cell attachment and proliferation are especially important for the materials used for tissue-engineering purposes. The results demonstrated that there is an optimum value for hydrophilicity and surface free energy which enhance cell attachment.

  8. Surface characterization of plasma-treated polypropylene fibers

    SciTech Connect

    Wei, Q.F

    2004-06-15

    Plasma treatment is increasingly being used for surface modification of different materials in many industries. In this study, different techniques were employed to characterize the surface properties of plasma treated polypropylene fibers. The chemical nature of the fiber sufaces has been investigated by X-ray photoelectron spectroscopy (XPS). The XPS examination indicated the presence of oxygen-containing functional groups on fiber surfaces after plasma treatment. The Atomic Force Microscopy (AFM) scans revealed the evolution of surface morphology under different experimental conditions. A Philips Environmental Scanning Electron Microscopy (ESEM) was also used to study the wetting behavior of the fibers. In the ESEM, relative humidity can be raised to 100% to facilitate the water condensation onto fiber surfaces for wetting observation. The ESEM observation revealed that the plasma treatment significantly altered the surface wettability of polypropylene fibers.

  9. Surface Engineering of Liposomes for Stealth Behavior

    PubMed Central

    Nag, Okhil K.; Awasthi, Vibhudutta

    2013-01-01

    Liposomes are used as a delivery vehicle for drug molecules and imaging agents. The major impetus in their biomedical applications comes from the ability to prolong their circulation half-life after administration. Conventional liposomes are easily recognized by the mononuclear phagocyte system and are rapidly cleared from the blood stream. Modification of the liposomal surface with hydrophilic polymers delays the elimination process by endowing them with stealth properties. In recent times, the development of various materials for surface engineering of liposomes and other nanomaterials has made remarkable progress. Poly(ethylene glycol)-linked phospholipids (PEG-PLs) are the best representatives of such materials. Although PEG-PLs have served the formulation scientists amazingly well, closer scrutiny has uncovered a few shortcomings, especially pertaining to immunogenicity and pharmaceutical characteristics (drug loading, targeting, etc.) of PEG. On the other hand, researchers have also begun questioning the biological behavior of the phospholipid portion in PEG-PLs. Consequently, stealth lipopolymers consisting of non-phospholipids and PEG-alternatives are being developed. These novel lipopolymers offer the potential advantages of structural versatility, reduced complement activation, greater stability, flexible handling and storage procedures and low cost. In this article, we review the materials available as alternatives to PEG and PEG-lipopolymers for effective surface modification of liposomes. PMID:24300562

  10. Engineering titanium surfaces for improving osteointegration

    NASA Astrophysics Data System (ADS)

    Lu, Xiong

    Titanium is one of the most important metallic biomedical materials in clinical applications. One of the key issues for successful application of titanium is the interaction at the interface between the titanium and the bone. The present study focuses on improving the surfaces of titanium to achieve better capability to bond with natural bone (i.e. better osteointegration). The objectives of this work include: (1) Developing microfabrication methods to produce micropatterns on titanium surfaces for promoting osteointegration; (2) Studying the calcium phosphate (Ca-P) formation on the chemical treated titanium surface and elucidating the mechanism of precipitation theoretically; and (3) Evaluating osteoconductivity of engineering titanium surfaces in vitro and in vivo. Through mask electrochemical micromachining (TMEMM), jet electrochemical micromachining (Jet-EMM) and the confined etchant layer technique (CELT) were attempted to produce micropatterns on titanium surfaces. TMEMM has a high etching rate and good reproducibility and was used to produce micro-hole arrays on Ti plates for in vivo testing. The driving force and nucleation rate of Ca-P precipitation in simulated body fluid (SBF) were analyzed based on the classical crystallization theory. SBF supersaturation with respect to HA, OCP and DCPD (dicalcium phosphate) was carefully calculated, considering all the association/dissociation reactions of related ion groups in SBF. The analysis indicates that the nucleation rate of OCP is substantially higher than that of HA, while HA is most thermodynamically stable in SBF. DCPD precipitation is thermodynamically impossible in normal SBF, unless calcium and phosphate ion concentrations of SBF increase. Osteoconduction of Ti6Al4V surfaces under various conditions, including micro-patterned, alkali-treated, micro-patterned plus alkali-treated, and surfaces without any treatment, was evaluated. TMEMM was used to fabricate micro-hole arrays on the titanium alloy

  11. Protective coatings of metal surfaces by cold plasma treatment

    NASA Technical Reports Server (NTRS)

    Manory, R.; Grill, A.

    1985-01-01

    The cold plasma techniques for deposition of various types of protective coatings are reviewed. The main advantage of these techniques for deposition of ceramic films is the lower process temperature, which enables heat treating of the metal prior to deposition. In the field of surface hardening of steel, significant reduction of treatment time and energy consumption were obtained. A simple model for the plasma - surface reactions in a cold plasma system is presented, and the plasma deposition techniques are discussed in view of this model.

  12. A dislocation-based crystal viscoplasticity model with application to micro-engineered plasma-facing materials

    NASA Astrophysics Data System (ADS)

    Rivera, David; Huang, Yue; Po, Giacomo; Ghoniem, Nasr M.

    2017-03-01

    Materials developed with special surface architecture are shown here to be more resilient to the transient thermomechanical environments imposed by intermittent exposures to high heat flux thermal loading typical of long-pulse plasma transients. In an accompanying article, we present experimental results that show the relaxation of residual thermal stresses in micro-engineered W surfaces. A dislocation-based model is extended here within the framework of large deformation crystal plasticity. The model is applied to the deformation of single crystals, polycrystals, and micro-engineered surfaces composed of a uniform density of micro-pillars. The model is utilized to design tapered surface micro-pillar architecture, composed of a Re core and W coatings. Residual stresses generated by cyclic thermomechanical loading of these architectures show that the surface can be in a compressive stress state, following a short shakedown plasma exposure, thus mitigating surface fracture.

  13. Etching of silicon surfaces using atmospheric plasma jets

    NASA Astrophysics Data System (ADS)

    Paetzelt, H.; Böhm, G.; Arnold, Th

    2015-04-01

    Local plasma-assisted etching of crystalline silicon by fine focused plasma jets provides a method for high accuracy computer controlled surface waviness and figure error correction as well as free form processing and manufacturing. We investigate a radio-frequency powered atmospheric pressure He/N2/CF4 plasma jet for the local chemical etching of silicon using fluorine as reactive plasma gas component. This plasma jet tool has a typical tool function width of about 0.5 to 1.8 mm and a material removal rate up to 0.068 mm3 min-1. The relationship between etching rate and plasma jet parameters is discussed in detail regarding gas composition, working distance, scan velocity and RF power. Surface roughness after etching was characterized using atomic force microscopy and white light interferometry. A strong smoothing effect was observed for etching rough silicon surfaces like wet chemically-etched silicon wafer backsides. Using the dwell-time algorithm for a deterministic surface machining by superposition of the local removal function of the plasma tool we show a fast and efficient way for manufacturing complex silicon structures. In this article we present two examples of surface processing using small local plasma jets.

  14. Effects of GlidArc plasma treatment on metallic surface

    NASA Astrophysics Data System (ADS)

    Astanei, D.; Ursache, M.; Hnatiuc, E.; Stoica, I.; Hnatiuc, B.; Felea, C.

    2016-12-01

    This paper presents the GlidArc plasma effects on some metallic surfaces often used in dentistry: zirconium, titanium and nickel - chromium alloy plates. For the experiments performed, a GlidArc reactor with two planar electrodes has been used. During the tests, the gas flow has been kept constant while the treatment time and the distance between the plasma and the sample were modified. The surfaces were analyzed using atomic force microscopy (AFM) in order to determine the surface morphological modifications induced by the plasma treatment.

  15. Femtosecond laser-induced electronic plasma at metal surface

    SciTech Connect

    Chen Zhaoyang; Mao, Samuel S.

    2008-08-04

    We develop a theoretical analysis to model plasma initiation at the early stage of femtosecond laser irradiation of metal surfaces. The calculation reveals that there is a threshold intensity for the formation of a microscale electronic plasma at the laser-irradidated metal surface. As the full width at half maximum of a laser pulse increases from 15 to 200 fs, the plasma formation threshold decreases by merely about 20%. The dependence of the threshold intensity on laser pulse width can be attributed to laser-induced surface electron emission, in particular due to the effect of photoelectric effect.

  16. Surface damage of W exposed to combined stationary D plasma and ELMs-like pulsed plasma

    NASA Astrophysics Data System (ADS)

    Jia, Y. Z.; Liu, W.; Xu, B.; Qu, S. L.; Morgan, T. W.

    2017-04-01

    The surface damage of W under D plasma and ELMs-like transient heat loads was studied by combined stationary and pulsed D plasma. Low-flux transient heat loads will promote blister formation due to the gas expansion inside the blisters. On the contrary, high-flux transient heat loads will mitigate blistering due to the high surface temperature. Therefore, blistering on W surface first increased and then decreased with the increasing transient heat loads. The promotion effect of pulsed plasma on blistering is more obvious on [001] and [110] surfaces than on [111] surface, and the orientation dependence of blisters was mitigated by the transient heat loads. Surface modification induced by transient heat loads only formed on [001] and [110] surfaces, but did not form on [111] surface. The orientation dependence of surface modification was mainly due to the slipping system of dislocations.

  17. Effect of Energetic Plasma Flux on Flowing Liquid Lithium Surfaces

    NASA Astrophysics Data System (ADS)

    Kalathiparambil, Kishor; Jung, Soonwook; Christenson, Michael; Fiflis, Peter; Xu, Wenyu; Szott, Mathew; Ruzic, David

    2014-10-01

    An operational liquid lithium system with steady state flow driven by thermo-electric magneto-hydrodynamic force and capable of constantly refreshing the plasma exposed surface have been demonstrated at U of I. To evaluate the system performance in reactor relevant conditions, specifically to understand the effect of disruptive plasma events on the performance of the liquid metal PFCs, the setup was integrated to a pulsed plasma generator. A coaxial plasma generator drives the plasma towards a theta pinch which preferentially heats the ions, simulating ELM like flux, and the plasma is further guided towards the target chamber which houses the flowing lithium system. The effect of the incident flux is examined using diagnostic tools including triple Langmuir probe, calorimeter, rogowski coils, Ion energy analyzers, and fast frame spectral image acquisition with specific optical filters. The plasma have been well characterized and a density of ~1021 m-3, with electron temperature ~10 - 20 eV is measured, and final plasma velocities of 34 - 74 kms-1 have been observed. Calorimetric measurements using planar molybdenum targets indicate a maximum plasma energy (with 6 kV plasma gun and 20 kV theta pinch) of 0.08 MJm-2 with plasma divergence effects resulting in marginal reduction of 40 +/- 23 J in plasma energy. Further results from the other diagnostic tools, using the flowing lithium targets and the planar targets coated with lithium will be presented. DOE DE-SC0008587.

  18. Charging time for dust grain on surface exposed to plasma

    SciTech Connect

    Sheridan, T. E.

    2013-04-14

    We consider the charging of a dust grain sitting on a surface exposed to plasma. The stochastic model of Sheridan and Hayes [Appl. Phys. Lett. 98, 091501 (2011)] is solved analytically for the charging time, which is found to be directly proportional to the square root of the electron temperature and inversely proportional to both the grain radius and plasma density.

  19. Surface modification of polymeric materials by plasma immersion ion implantation

    NASA Astrophysics Data System (ADS)

    Fu, Ricky K. Y.; Cheung, I. T. L.; Mei, Y. F.; Shek, C. H.; Siu, G. G.; Chu, Paul K.; Yang, W. M.; Leng, Y. X.; Huang, Y. X.; Tian, X. B.; Yang, S. Q.

    2005-08-01

    Polymer surfaces typically have low surface tension and high chemical inertness and so they usually have poor wetting and adhesion properties. The surface properties can be altered by modifying the molecular structure using plasma immersion ion implantation (PIII). In this work, Nylon-6 was treated using oxygen/nitrogen PIII. The observed improvement in the wettability is due to the oxygenated and nitrogen (amine) functional groups created on the polymer surface by the plasma treatment. X-ray photoelectron spectroscopy (XPS) results show that nitrogen and oxygen plasma implantation result in C-C bond breaking to form the imine and amine groups as well as alcohol and/or carbonyl groups on the surface. The water contact angle results reveal that the surface wetting properties depend on the functional groups, which can be adjusted by the ratio of oxygen-nitrogen mixtures.

  20. Surface plasma treatment of poly(caprolactone) micro, nano, and multiscale fibrous scaffolds for enhanced osteoconductivity.

    PubMed

    Sankar, Deepthi; Shalumon, K T; Chennazhi, K P; Menon, Deepthy; Jayakumar, R

    2014-06-01

    In this study, poly(caprolactone) (PCL) was electrospun to nano, micro, and multiscale (micro-nano) fibers, which were then subjected to low pressure argon and nitrogen plasma treatment. The electrospun fibers contain microfibers of diameter 8-10 μm and nanofibers of diameter 200-300 nm. Characterization of the plasma-treated fibers showed that treatment using less oxidizing gas like nitrogen and inert gas like argon functionalize the surface with polar groups that significantly modify the properties of the scaffold. Highly hydrophobic PCL fibrous scaffolds were rendered hydrophilic, with significantly improved biomineralization after the plasma treatment. While plasma treatment on micro and multiscale fibers enhanced their protein adsorption, cell attachment, spreading, elongation, and proliferation, nanofibers showed remarkably improved cell attachment. The applicability of plasma-treated electrospun fibers for differentiation of mesenchymal stem cell toward osteogenic lineage was also studied. Accelerated differentiation toward osteoblast lineage, with maximum alkaline phosphatase (ALP) activity in 14 days was achieved in plasma-treated fibers. Another remarkable outcome was the enhanced ALP activity of the microfibers after plasma treatment, compared with multiscale and nanofibers. Alizarin red staining further confirmed the mineralization of the plasma-treated scaffolds, indicative of maturation of the differentiated cells. This work thus concentrates on harnessing the potential of plasma treatment, for improving the osteoconductivity of fibrous scaffolds, which could be used for bone tissue engineering/regenerative medicine.

  1. Acellular assessments of engineered-manufactured nanoparticle biological surface reactivity

    EPA Science Inventory

    It is critical to assess the surface properties and reactivity of engineered-manufactured nanoparticles (NPs) as these will influence their interactions with biological systems, biokinetics and toxicity. We examined the physicochemical properties and surface reactivity of metal o...

  2. Facet‐Engineered Surface and Interface Design of Photocatalytic Materials

    PubMed Central

    Wang, Lili; Li, Zhengquan

    2016-01-01

    The facet‐engineered surface and interface design for photocatalytic materials has been proven as a versatile approach to enhance their photocatalytic performance. This review article encompasses some recent advances in the facet engineering that has been performed to control the surface of mono‐component semiconductor systems and to design the surface and interface structures of multi‐component heterostructures toward photocatalytic applications. The review begins with some key points which should receive attention in the facet engineering on photocatalytic materials. We then discuss the synthetic approaches to achieve the facet control associated with the surface and interface design. In the following section, the facet‐engineered surface design on mono‐component photocatalytic materials is introduced, which forms a basis for the discussion on more complex systems. Subsequently, we elucidate the facet‐engineered surface and interface design of multi‐component photocatalytic materials. Finally, the existing challenges and future prospects are discussed. PMID:28105398

  3. Engineering Polarons at a Metal Oxide Surface

    NASA Astrophysics Data System (ADS)

    Yim, C. M.; Watkins, M. B.; Wolf, M. J.; Pang, C. L.; Hermansson, K.; Thornton, G.

    2016-09-01

    Polarons in metal oxides are important in processes such as catalysis, high temperature superconductivity, and dielectric breakdown in nanoscale electronics. Here, we study the behavior of electron small polarons associated with oxygen vacancies at rutile TiO2(110 ) , using a combination of low temperature scanning tunneling microscopy (STM), density functional theory, and classical molecular dynamics calculations. We find that the electrons are symmetrically distributed around isolated vacancies at 78 K, but as the temperature is reduced, their distributions become increasingly asymmetric, confirming their polaronic nature. By manipulating isolated vacancies with the STM tip, we show that particular configurations of polarons are preferred for given locations of the vacancies, which we ascribe to small residual electric fields in the surface. We also form a series of vacancy complexes and manipulate the Ti ions surrounding them, both of which change the associated electronic distributions. Thus, we demonstrate that the configurations of polarons can be engineered, paving the way for the construction of conductive pathways relevant to resistive switching devices.

  4. Solitary Surface Waves at a Plasma Boundary

    NASA Astrophysics Data System (ADS)

    Gradov, O. M.; Stenflo, L.

    A new equation describing the behaviour of strongly nonlinear waves localized near the boundary of a semi-infinite plasma is deduced. This equation has solitary wave solutions that can be found numerically. Various limiting cases are treated analytically in the present paper.

  5. A Nanosecond Pulsed Plasma Brush for Surface Decontamination

    NASA Astrophysics Data System (ADS)

    Neuber, Johanna; Malik, Muhammad; Song, Shutong; Jiang, Chunqi

    2015-11-01

    This work optimizes a non-thermal, atmospheric pressure plasma brush for surface decontamination. The generated plasma plumes with a maximum length of 2 cm are arranged in a 5 cm long, brush-like array. The plasma was generated in ambient air with <= 10 kV, 200 ns pulses at a repetition rate of 1.5 kHz. The energy per pulse and average power are in the range of 1-3 mJ and 0.5-1.5 W, respectively. Helium containing varying concentrations of water vapor was evaluated as the carrier gas and was fed into the plasma chamber at a rate varying between 1 to 7 SLPM. Optimization of the cold plasma brush for surface decontamination was tested in a study of the plasma inactivation of two common pathogens, Staphylococcus aureus and Acinetobacter baumannii. Laminate surfaces inoculated with over-night cultured bacteria were subject to the plasma treatment for varying water concentrations in He, flow rates and discharge voltages. It was found that increasing the water content of the feed gas greatly enhanced the bactericidal effect. Emission spectroscopy was performed to identify the reactive plasma species that contribute to this variation. Additional affiliation: Frank Reidy Research Center for Bioelectrics

  6. Plasma Surface Presented as Array of Virtual Ports

    SciTech Connect

    Kyrytsya, V.; Koch, R.

    2009-11-26

    Calculations aimed at representing the plasma-vacuum boundary condition in real space are presented. Some ideas about how this representation can be used for power coupling analysis and antenna modeling are put forward. The relation between tangential electric and magnetic fields on the plasma surface is linear and customary expressed in the spectral domain for every partial wave via 2x2 plasma impedance matrix - Z{sup p}(k{sub y},K{sub z}). In this work, the tangential fields E-vector{sub t} and B-vector{sub t} on the plasma surface are projected on a suitably chosen set of basis functions. Then the linear operator relating the components E-vector{sub t} and B-vector{sub t} expressed in such a way is derived from the known matrix Z{sup p}(k{sub y},K{sub z}). It is shown that in this representation the plasma surface has properties similar to the array of ports of a microwave system and can be formally described by a corresponding impedance matrix in the way it is done in microwave analysis. The obtained representation can be exploited for deeper understanding of the RF power coupling to the plasmas, antenna modeling, measurements of plasma electromagnetic properties and for plasma modeling with suitably designed structures or metamaterials.

  7. Strongly Emitting Surfaces Unable to Float below Plasma Potential

    DOE PAGES

    Campanell, M. D.; Umansky, M. V.

    2016-02-25

    One important unresolved question in plasma physics concerns the effect of strong electron emission on plasma-surface interactions. Previous papers reported solutions with negative and positive floating potentials relative to the plasma edge. For these two models a very different predictions for particle and energy balance is given. Here we show that the positive potential state is the only possible equilibrium in general. Even if a negative floating potential existed at t=0, the ionization collisions near the surface will force a transition to the positive floating potential state. Moreover, this transition is demonstrated with a new simulation code.

  8. Helium segregation on surfaces of plasma-exposed tungsten

    SciTech Connect

    Maroudas, Dimitrios; Blondel, Sophie; Hu, Lin; Hammond, Karl D.; Wirth, Brian D.

    2016-01-21

    Here we report a hierarchical multi-scale modeling study of implanted helium segregation on surfaces of tungsten, considered as a plasma facing component in nuclear fusion reactors. We employ a hierarchy of atomic-scale simulations based on a reliable interatomic interaction potential, including molecular-statics simulations to understand the origin of helium surface segregation, targeted molecular-dynamics (MD) simulations of near-surface cluster reactions, and large-scale MD simulations of implanted helium evolution in plasma-exposed tungsten. We find that small, mobile He-n (1 <= n <= 7) clusters in the near-surface region are attracted to the surface due to an elastic interaction force that provides the thermodynamic driving force for surface segregation. Elastic interaction force induces drift fluxes of these mobile Hen clusters, which increase substantially as the migrating clusters approach the surface, facilitating helium segregation on the surface. Moreover, the clusters' drift toward the surface enables cluster reactions, most importantly trap mutation, in the near-surface region at rates much higher than in the bulk material. Moreover, these near-surface cluster dynamics have significant effects on the surface morphology, near-surface defect structures, and the amount of helium retained in the material upon plasma exposure. We integrate the findings of such atomic-scale simulations into a properly parameterized and validated spatially dependent, continuum-scale reaction-diffusion cluster dynamics model, capable of predicting implanted helium evolution, surface segregation, and its near-surface effects in tungsten. This cluster-dynamics model sets the stage for development of fully atomistically informed coarse-grained models for computationally efficient simulation predictions of helium surface segregation, as well as helium retention and surface morphological evolution, toward optimal design of plasma facing components.

  9. Helium segregation on surfaces of plasma-exposed tungsten

    DOE PAGES

    Maroudas, Dimitrios; Blondel, Sophie; Hu, Lin; ...

    2016-01-21

    Here we report a hierarchical multi-scale modeling study of implanted helium segregation on surfaces of tungsten, considered as a plasma facing component in nuclear fusion reactors. We employ a hierarchy of atomic-scale simulations based on a reliable interatomic interaction potential, including molecular-statics simulations to understand the origin of helium surface segregation, targeted molecular-dynamics (MD) simulations of near-surface cluster reactions, and large-scale MD simulations of implanted helium evolution in plasma-exposed tungsten. We find that small, mobile He-n (1 <= n <= 7) clusters in the near-surface region are attracted to the surface due to an elastic interaction force that provides themore » thermodynamic driving force for surface segregation. Elastic interaction force induces drift fluxes of these mobile Hen clusters, which increase substantially as the migrating clusters approach the surface, facilitating helium segregation on the surface. Moreover, the clusters' drift toward the surface enables cluster reactions, most importantly trap mutation, in the near-surface region at rates much higher than in the bulk material. Moreover, these near-surface cluster dynamics have significant effects on the surface morphology, near-surface defect structures, and the amount of helium retained in the material upon plasma exposure. We integrate the findings of such atomic-scale simulations into a properly parameterized and validated spatially dependent, continuum-scale reaction-diffusion cluster dynamics model, capable of predicting implanted helium evolution, surface segregation, and its near-surface effects in tungsten. This cluster-dynamics model sets the stage for development of fully atomistically informed coarse-grained models for computationally efficient simulation predictions of helium surface segregation, as well as helium retention and surface morphological evolution, toward optimal design of plasma facing components.« less

  10. Helium segregation on surfaces of plasma-exposed tungsten

    NASA Astrophysics Data System (ADS)

    Maroudas, Dimitrios; Blondel, Sophie; Hu, Lin; Hammond, Karl D.; Wirth, Brian D.

    2016-02-01

    We report a hierarchical multi-scale modeling study of implanted helium segregation on surfaces of tungsten, considered as a plasma facing component in nuclear fusion reactors. We employ a hierarchy of atomic-scale simulations based on a reliable interatomic interaction potential, including molecular-statics simulations to understand the origin of helium surface segregation, targeted molecular-dynamics (MD) simulations of near-surface cluster reactions, and large-scale MD simulations of implanted helium evolution in plasma-exposed tungsten. We find that small, mobile He n (1  ⩽  n  ⩽  7) clusters in the near-surface region are attracted to the surface due to an elastic interaction force that provides the thermodynamic driving force for surface segregation. This elastic interaction force induces drift fluxes of these mobile He n clusters, which increase substantially as the migrating clusters approach the surface, facilitating helium segregation on the surface. Moreover, the clusters’ drift toward the surface enables cluster reactions, most importantly trap mutation, in the near-surface region at rates much higher than in the bulk material. These near-surface cluster dynamics have significant effects on the surface morphology, near-surface defect structures, and the amount of helium retained in the material upon plasma exposure. We integrate the findings of such atomic-scale simulations into a properly parameterized and validated spatially dependent, continuum-scale reaction-diffusion cluster dynamics model, capable of predicting implanted helium evolution, surface segregation, and its near-surface effects in tungsten. This cluster-dynamics model sets the stage for development of fully atomistically informed coarse-grained models for computationally efficient simulation predictions of helium surface segregation, as well as helium retention and surface morphological evolution, toward optimal design of plasma facing components.

  11. Micro-plasma textured Ti-implant surfaces.

    PubMed

    Beck, U; Lange, R; Neumann, H-G

    2007-02-01

    The surface state of titanium implants modulates bone response and implant anchorage. This evidence brought implant manufacturers to switch from the standard surface refinements and implement new surface treatments for more bone apposition and enhanced interfacial strength measured by removal torque or push-out tests. Anodic plasma-chemical treatment of implant surfaces is a cost-effective process to modify surface topography and chemistry. This technique is used for structuring connected with a coating of implant surfaces. The aim of our investigations, here, is to texture the implant surface in the nanoscale without coating. Ti disks with different mechanical pre-treatment (grinded, glass blasted) were used as substrate. Micro-plasma texturing was carried out in an aqueous electrolyte. By applying a pulsed DC voltage to the specimen, micro-plasma discharge was generated in the thin steam film between immersed specimen and electrolyte. The electrical process parameter current density was varied. The micro-plasma textured Ti surfaces were characterised optically by SEM and electrochemically by CV- (for testing the corrosion parameters), CA- (to give the enlargement of the real surface) and EIS-measurement in range of 100 kHz-100 microHz. We found that the initial structure of the material surface has small or no influence on the results of the micro-plasma treatment. The properties of the thick oxide layer resulting from the plasma process are influenced by electrical process parameters. After removal of the thick oxide layer a fine, micro- and nanoscaled surface structure of the titanium remains.

  12. Influence of emitted electrons transiting between surfaces on plasma-surface interaction

    SciTech Connect

    Campanell, Michael; Wang, Hongyue

    2013-09-02

    Emitted electrons are accelerated back into the plasma by the sheath. If their mean free path is large, they can propagate directly to another surface without suffering collisions. We analyze the effects of “transit” on plasma-surface interaction. When transit occurs, surfaces exchanging electrons are intricately coupled. All surfaces float more negatively than they would if the emission collisionally remixed with the bulk plasma. Asymmetries of the system drive a net “transit current” between the surfaces, which influences their potential difference. The larger the initial energy spread of the emitted electrons, the larger the potential difference.

  13. Plasma Flow Interaction With Iter Divertor Related Surfaces

    NASA Astrophysics Data System (ADS)

    Dojcinovic, I. P.

    2010-07-01

    It has been found that the plasma flow generated by quasistationary plasma accelerators can be used for simulation of high energy plasma interaction with different materials of interest for fusion experiments (Arkhipov et al. 2000, Federici et al. 2005). It is especially important for the studies of the processes such as ELMs (edge localized modes), plasma disruptions and VDEs (vertical displacement events), during which a significant part of the confined hot plasma is lost from the core to the SOL (scrape off layer) enveloping the core region. Experiments using plasma guns have been used to assess erosion from disruptions and ELMs. Namely, in this experiment modification of different targets, like molybdenum, CFC and silicon single crystal surface by the action of hydrogen and nitrogen quasistationary compression plasma flow (CPF) generated by magnetoplasma compressor (MPC) has been studied. MPC plasma flow with standard parameters (1 MJ/m^2 in 0.1 ms) can be used for simulation of transient peak thermal loads during Type I ELMs and disruptions (Dojcinovic et al. 2007). Analysis of the targets erosion, brittle destruction, melting processes, and dust formation has been performed (Dojcinovic et al. 2006). These surface phenomena are results of specific conditions during CPF interaction with target surface. The investigations are related to the fundamental aspects of high energy plasma flow interaction with different material of interest for fusion. One of the purposes is a study of competition between melting and cleavage of treated solid surface. The other is investigation of plasma interaction with first wall and divertor component materials related to the ITER experiment.

  14. Plasma modification of HEMA and EOEMA surface properties

    NASA Astrophysics Data System (ADS)

    Svorcik, V.; Kolarova, K.; Dvorankova, B.; Michalek, J.; Krumbholcova, E.; Hnatowicz, V.

    2006-01-01

    Process of plasma etching of poly(2-hydroxyethylmethacrylate) (HEMA) and poly(2-ethyloxyethyl methacrylate) (EOEMA) in Ar atmosphere at room temperature was studied. Ablation of the samples exposed to the plasma was determined by gravimetry, surface wettability by goniometry, chemical structure by FTIR spectroscopy and surface morphology by Scanning Electron (SEM) microscopy. Adhesion and proliferation of 3T3 mouse fibroblasts was studied in vitro in order to determine biological activity of plasma-modified HEMA and EOEMA substrates. It was demonstrated that the plasma etching leads to oxidation of HEMA and to an increase of its wettability. More estheric structures are produced in EOEMA. For both polymers, a surface layer similar to 2 mu m thick is ablated after plasma etching for 400 s. The etching changes the sample surface morphology and its biological activity. The surface becomes smoother after etching. The results obtained after 3T3 cells cultivation show that the plasma etching decreases cell adhesion and increases cell proliferation in comparison with pristine polymers.

  15. Dust generation at interaction of plasma jet with surfaces

    NASA Astrophysics Data System (ADS)

    Ticos, Catalin; Toader, Dorina; Banu, Nicoleta; Scurtu, Adrian; Oane, Mihai

    2013-10-01

    Coatings of W and C with widths of a few microns will be exposed to plasma jet for studying the erosion of the surface and detachment of micron size dust particles. A coaxial plasma gun has been built inside a vacuum chamber for producing supersonic plasma jets. Its design is based on a 50 kJ coaxial plasma gun which has been successfully used for accelerating hypervelocity dust. Initial shots were carried out for a capacitor bank with C = 12 μF and charged up to 2 kV. Currents of tens of amps were measured with a Rogowsky coil and plasma flow speeds of 4 km/s were inferred from high-speed images of jet propagation. An upgrade consisting in adding capacitors in parallel will be performed in order to increase the energy up to 2 kJ. A coil will be installed at the gun muzzle to compress the plasma flow and increase the energy density of the jet on the sample surface. A CCD camera with a maximum recording speed of 100 k fps and a maximum resolution of 1024 × 1024 pixels was set for image acquisition of the plasma and dust. A laser system used to illuminate the ejected dust from the surface includes a laser diode emitting at 650 nm with a beam power of 25 mW. The authors acknowledge support from EURATOM WP13-IPH-A03-P2-02-BS22.

  16. Mechanistic Study of Plasma Damage of Low k Dielectric Surfaces

    SciTech Connect

    Bao Junjing; Shi Hualiang; Huang Huai; Ho, P. S.; Liu Junjun; Goodner, M. D.; Moinpour, M.; Kloster, G. M.

    2007-10-31

    Plasma damage to low k dielectric materials was investigated from a mechanistic point of view. Low k dielectric films were treated by plasma Ar, O{sub 2}, N{sub 2}/H{sub 2}, N{sub 2} and H{sub 2} in a standard RIE chamber and the damage was characterized by Angle Resolved X-ray Photoelectron Spectroscopy (ARXPS), X-Ray Reflectivity (XRR), Fourier Transform Infrared Spectroscopy (FTIR) and Contact Angle measurements. Both carbon depletion and surface densification were observed on the top surface of damaged low k materials while the bulk remained largely unaffected. Plasma damage was found to be a complicated phenomenon involving both chemical and physical effects, depending on chemical reactivity and the energy and mass of the plasma species. A downstream hybrid plasma source with separate ions and atomic radicals was employed to study their respective roles in the plasma damage process. Ions were found to play a more important role in the plasma damage process. The dielectric constant of low k materials can increase up to 20% due to plasma damage and we attributed this to the removal of the methyl group making the low k surface hydrophilic. Annealing was generally effective in mitigating moisture uptake to restore the k value but the recovery was less complete for higher energy plasmas. Quantum chemistry calculation confirmed that physisorbed water in low k materials induces the largest increase of dipole moments in comparison with changes of surface bonding configurations, and is primarily responsible for the dielectric constant increase.

  17. High speed cine film studies of plasma behaviour and plasma surface interactions in tokamaks

    NASA Astrophysics Data System (ADS)

    Goodall, D. H. J.

    1982-12-01

    High speed cine photography is a useful diagnostic aid for studying plasma behaviour and plasma surface interactions. Several workers have filmed discharges in tokamaks including ASDEX, DITE, DIVA, ISX, JFT2, TFR and PLT. These films are discussed and examples given of the observed phenomena which include plasma limiter interactions, diverted discharges, disruptions, magnetic islands and moving glowing objects often known as 'UFOs'. Examples of plasma structures in ASDEX and DITE not previously published are also given. The paper also reports experiments in DITE to determine the origin of UFOs.

  18. Low Temperature Plasma Surface Interactions: Atomic Layer Etching And Atmospheric Pressure Plasma Jet Modification Of Biomaterials

    NASA Astrophysics Data System (ADS)

    Oehrlein, Gottlieb

    2013-09-01

    Control of plasma-surface interactions is essential for successful application of low temperature plasma to materials processing. We review work performed in our laboratory in two areas: First, low pressure plasma surface interaction mechanisms aimed at achieving atomic precision in etching materials in the semiconductor industry. We discuss sequential reactions of surface passivation followed by directional low energy ion attack for ``volatile product'' removal to establish for what conditions self-limiting behavior required for Atomic Layer Etching (ALE) can be established using prototypical SiO2 -Si/fluorocarbon-Ar materials/etching systems. Second, studies of plasma-surface interactions related to application of a non-equilibrium atmospheric pressure plasma jet (APPJ) for modification of biomaterials are discussed. Changes in surface chemistry/biological activity of lipopolysaccharide (LPS) exposed to the APPJ plume/effluent in a controlled environment are reviewed. The results clarify how jet chemistry and interactions of plasma with the environment impact the consequences of APPJ-biomaterial-surface interactions. Based on collaborations with D. Metzler, S. Engelmann, R. Bruce, E. Joseph, E. Bartis, C. Hart, Q.-Y. Yang, J. Seog, T.-Y. Chung, H.-W. Chang, and D.B. Graves. We gratefully acknowledge funding from US Department of Energy (DE-SC0005105; DE-SC0001939) and National Science Foundation (CBET-1134273; PHY-1004256).

  19. Bone tissue response to plasma-nitrided titanium implant surfaces

    PubMed Central

    FERRAZ, Emanuela Prado; SVERZUT, Alexander Tadeu; FREITAS, Gileade Pereira; SÁ, Juliana Carvalho; ALVES, Clodomiro; BELOTI, Marcio Mateus; ROSA, Adalberto Luiz

    2015-01-01

    A current goal of dental implant research is the development of titanium (Ti) surfaces to improve osseointegration. Plasma nitriding treatments generate surfaces that favor osteoblast differentiation, a key event to the process of osteogenesis. Based on this, it is possible to hypothesize that plasma-nitrided Ti implants may positively impact osseointegration. Objective The aim of this study was to evaluate the in vivo bone response to Ti surfaces modified by plasma-nitriding treatments. Material and Methods Surface treatments consisted of 20% N2 and 80% H2, 450°C and 1.5 mbar during 1 h for planar and 3 h for hollow cathode. Untreated surface was used as control. Ten implants of each surface were placed into rabbit tibiae and 6 weeks post-implantation they were harvested for histological and histomorphometric analyses. Results Bone formation was observed in contact with all implants without statistically significant differences among the evaluated surfaces in terms of bone-to-implant contact, bone area between threads, and bone area within the mirror area. Conclusion Our results indicate that plasma nitriding treatments generate Ti implants that induce similar bone response to the untreated ones. Thus, as these treatments improve the physico-chemical properties of Ti without affecting its biocompatibility, they could be combined with modifications that favor bone formation in order to develop new implant surfaces. PMID:25760262

  20. Plasma assisted surface coating/modification processes - An emerging technology

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1987-01-01

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

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

    NASA Astrophysics Data System (ADS)

    Spalvins, T.

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

  2. Plasma assisted surface coating/modification processes - An emerging technology

    NASA Astrophysics Data System (ADS)

    Spalvins, T.

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

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

    NASA Technical Reports Server (NTRS)

    Spalvins, T.

    1986-01-01

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

  4. Solar energy converter using surface plasma waves

    NASA Technical Reports Server (NTRS)

    Anderson, L. M. (Inventor)

    1984-01-01

    Sunlight is dispersed over a diffraction grating formed on the surface of a conducting film on a substrate. The angular dispersion controls the effective grating period so that a matching spectrum of surface plasmons is excited for parallel processing on the conducting film. The resulting surface plasmons carry energy to an array of inelastic tunnel diodes. This solar energy converter does not require different materials for each frequency band, and sunlight is directly converted to electricity in an efficient manner by extracting more energy from the more energetic photons.

  5. Surface acoustical intensity measurements on a diesel engine

    NASA Technical Reports Server (NTRS)

    Mcgary, M. C.; Crocker, M. J.

    1980-01-01

    The use of surface intensity measurements as an alternative to the conventional selective wrapping technique of noise source identification and ranking on diesel engines was investigated. A six cylinder, in line turbocharged, 350 horsepower diesel engine was used. Sound power was measured under anechoic conditions for eight separate parts of the engine at steady state operating conditions using the conventional technique. Sound power measurements were repeated on five separate parts of the engine using the surface intensity at the same steady state operating conditions. The results were compared by plotting sound power level against frequency and noise source rankings for the two methods.

  6. Investigation of an Oscillating Surface Plasma for Turbulent Drag Reduction

    NASA Technical Reports Server (NTRS)

    Wilkinson, Stephen P.

    2003-01-01

    An oscillating, weakly ionized surface plasma has been investigated for use in turbulent boundary layer viscous drag reduction. The study was based on reports showing that mechanical spanwise oscillations of a wall can reduce viscous drag due to a turbulent boundary layer by up to 40%. It was hypothesized that the plasma induced body force in high electric field gradients of a surface plasma along strip electrodes could also be configured to oscillate the flow. Thin dielectric panels with millimeter-scale, flush- mounted, triad electrode arrays with one and two-phase high voltage excitation were tested. Results showed that while a small oscillation could be obtained, the effect was lost at a low frequency (less than 100Hz). Furthermore, a mean flow was generated during the oscillation that complicates the effect. Hot-wire and pitot probe diagnostics are presented along with phase-averaged images revealing plasma structure.

  7. Research of surface plasma resonance optical fiber hydrogen sensor

    NASA Astrophysics Data System (ADS)

    Ou, Zhonghua; Guo, Xiaowei; Chen, Dejun; Dai, Zhiyong; Peng, Zengshou; Liu, Yongzhi

    2008-12-01

    An optical fiber hydrogen sensor based on the measuring principle of surface plasma resonance is introduced. The structure of the hydrogen-sensitive head which is coated with Pd-Ag alloy film on the surface of the etched optical fiber is investigated theoretically. When hydrogen gas is absorbed into the Pd thin layer of the sensing head, the Pd hydride is formed and then the refraction index of the etched optical fiber surface will be changed with different hydrogen gas concentration. The surface plasma wave is stimulated by the light wave in optical fiber and the surface plasma resonance occurs between the thin metal layer and the medium surface of hydrogen gas. The Pd-Ag alloy film thickness versus the sensitivity of hydrogen sensing head is analyzed and optimized via the numerical method. The sensing head which is based on surface plasma resonance is manufactured and used in the experiment system of hydrogen gas detecting, and the experiment results demonstrate that the detecting system has high sensitivity with the hydrogen concentration in the range of 0%-4%, the accuracy, resolution and response time are respectively 5%, 0.1% and 30s. This sensor structure can be applied to detecting the low concentration of hydrogen gas.

  8. Helium atmospheric pressure plasma jets touching dielectric and metal surfaces

    NASA Astrophysics Data System (ADS)

    Norberg, Seth A.; Johnsen, Eric; Kushner, Mark J.

    2015-07-01

    Atmospheric pressure plasma jets (APPJs) are being investigated in the context plasma medicine and biotechnology applications, and surface functionalization. The composition of the surface being treated ranges from plastics, liquids, and biological tissue, to metals. The dielectric constant of these materials ranges from as low as 1.5 for plastics to near 80 for liquids, and essentially infinite for metals. The electrical properties of the surface are not independent variables as the permittivity of the material being treated has an effect on the dynamics of the incident APPJ. In this paper, results are discussed from a computational investigation of the interaction of an APPJ incident onto materials of varying permittivity, and their impact on the discharge dynamics of the plasma jet. The computer model used in this investigation solves Poisson's equation, transport equations for charged and neutral species, the electron energy equation, and the Navier-Stokes equations for the neutral gas flow. The APPJ is sustained in He/O2 = 99.8/0.2 flowing into humid air, and is directed onto dielectric surfaces in contact with ground with dielectric constants ranging from 2 to 80, and a grounded metal surface. Low values of relative permittivity encourage propagation of the electric field into the treated material and formation and propagation of a surface ionization wave. High values of relative permittivity promote the restrike of the ionization wave and the formation of a conduction channel between the plasma discharge and the treated surface. The distribution of space charge surrounding the APPJ is discussed.

  9. Antiproton powered propulsion with magnetically confined plasma engines

    NASA Technical Reports Server (NTRS)

    Lapointe, Michael R.

    1989-01-01

    The reaction of the matter-antimatter annihilation, with its specific energy being over 250 times the specific energy released in nuclear fusion, is considered as an energy source for spacecraft propulsion. A concept of a magnetically confined pulsed plasma engine is described. In this concept, antiproton beams are injected axially into a pulsed magnetic mirror system, where they annihilate with an initially neutral hydrogen gas; the resulting charge annihilation products transfer energy to the hydrogen propellant, which is then exhausted through one end of the pulsed mirror system to provide thrust. Numerical simulations were developed to calculate the annihilation rate of antiprotons in hydrogen and to follow the resulting ion, muon, and electron/positron number density evolutions.

  10. Antiproton powered propulsion with magnetically confined plasma engines

    SciTech Connect

    Lapointe, M.R.

    1989-01-01

    The reaction of the matter-antimatter annihilation, with its specific energy being over 250 times the specific energy released in nuclear fusion, is considered as an energy source for spacecraft propulsion. A concept of a magnetically confined pulsed plasma engine is described. In this concept, antiproton beams are injected axially into a pulsed magnetic mirror system, where they annihilate with an initially neutral hydrogen gas; the resulting charge annihilation products transfer energy to the hydrogen propellant, which is then exhausted through one end of the pulsed mirror system to provide thrust. Numerical simulations were developed to calculate the annihilation rate of antiprotons in hydrogen and to follow the resulting ion, muon, and electron/positron number density evolutions. 22 refs.

  11. Quantification of air plasma chemistry for surface disinfection

    NASA Astrophysics Data System (ADS)

    Pavlovich, Matthew J.; Clark, Douglas S.; Graves, David B.

    2014-12-01

    Atmospheric-pressure air plasmas, created by a variety of discharges, are promising sources of reactive species for the emerging field of plasma biotechnology because of their convenience and ability to operate at ambient conditions. One biological application of ambient-air plasma is microbial disinfection, and the ability of air plasmas to decontaminate both solid surfaces and liquid volumes has been thoroughly established in the literature. However, the mechanism of disinfection and which reactive species most strongly correlate with antimicrobial effects are still not well understood. We describe quantitative gas-phase measurements of plasma chemistry via infrared spectroscopy in confined volumes, focusing on air plasma generated via surface micro-discharge (SMD). Previously, it has been shown that gaseous chemistry is highly sensitive to operating conditions, and the measurements we describe here extend those findings. We quantify the gaseous concentrations of ozone (O3) and nitrogen oxides (NO and NO2, or NOx) throughout the established ‘regimes’ for SMD air plasma chemistry: the low-power, ozone-dominated mode; the high-power, nitrogen oxides-dominated mode; and the intermediate, unstable transition region. The results presented here are in good agreement with previously published experimental studies of aqueous chemistry and parameterized models of gaseous chemistry. The principal finding of the present study is the correlation of bacterial inactivation on dry surfaces with gaseous chemistry across these time and power regimes. Bacterial decontamination is most effective in ‘NOx mode’ and less effective in ‘ozone mode’, with the weakest antibacterial effects in the transition region. Our results underscore the dynamic nature of air plasma chemistry and the importance of careful chemical characterization of plasma devices intended for biological applications.

  12. Lithium-based surfaces controlling fusion plasma behavior at the plasma-material interfacea)

    NASA Astrophysics Data System (ADS)

    Allain, Jean Paul; Taylor, Chase N.

    2012-05-01

    The plasma-material interface and its impact on the performance of magnetically confined thermonuclear fusion plasmas are considered to be one of the key scientific gaps in the realization of nuclear fusion power. At this interface, high particle and heat flux from the fusion plasma can limit the material's lifetime and reliability and therefore hinder operation of the fusion device. Lithium-based surfaces are now being used in major magnetic confinement fusion devices and have observed profound effects on plasma performance including enhanced confinement, suppression and control of edge localized modes (ELM), lower hydrogen recycling and impurity suppression. The critical spatial scale length of deuterium and helium particle interactions in lithium ranges between 5-100 nm depending on the incident particle energies at the edge and magnetic configuration. Lithium-based surfaces also range from liquid state to solid lithium coatings on a variety of substrates (e.g., graphite, stainless steel, refractory metal W/Mo/etc., or porous metal structures). Temperature-dependent effects from lithium-based surfaces as plasma facing components (PFC) include magnetohydrodynamic (MHD) instability issues related to liquid lithium, surface impurity, and deuterium retention issues, and anomalous physical sputtering increase at temperatures above lithium's melting point. The paper discusses the viability of lithium-based surfaces in future burning-plasma environments such as those found in ITER and DEMO-like fusion reactor devices.

  13. Camshaft surface temperatures in fired-gasoline engines

    SciTech Connect

    McGeehan, J.A.; Graham, J.P.; Yamaguchi, E.S.

    1990-01-01

    The authors of this paper measured camshaft surface temperatures in to different gasoline engines: a Ford 2.3-litter overhead-camshaft engine with finger-follower and an Oldsmobile V-8 5.7-liter engine with rotating tappets and pushrods. Using unique surface thermocouples in the cam-lobes, we found that maximum cam-lob temperature occur at the cam-nose and increase linearly with speed and oil temperature. At high speed, the rotating tappet produced lower temperatures that the finger-follower. In addition, at maximum speed the cam-lobe temperatures in the ASTM Sequence V-D and IIID tests were similar--200{degrees} C. The similarity in these surface temperatures explains why both engines require similar zinc dithiophosphates (SnDTP) for wear control. The surface temperature controls the surface chemistry.

  14. Standard Reference Specimens in Quality Control of Engineering Surfaces

    PubMed Central

    Song, J. F.; Vorburger, T. V.

    1991-01-01

    In the quality control of engineering surfaces, we aim to understand and maintain a good relationship between the manufacturing process and surface function. This is achieved by controlling the surface texture. The control process involves: 1) learning the functional parameters and their control values through controlled experiments or through a long history of production and use; 2) maintaining high accuracy and reproducibility with measurements not only of roughness calibration specimens but also of real engineering parts. In this paper, the characteristics, utilizations, and limitations of different classes of precision roughness calibration specimens are described. A measuring procedure of engineering surfaces, based on the calibration procedure of roughness specimens at NIST, is proposed. This procedure involves utilization of check specimens with waveform, wavelength, and other roughness parameters similar to functioning engineering surfaces. These check specimens would be certified under standardized reference measuring conditions, or by a reference instrument, and could be used for overall checking of the measuring procedure and for maintaining accuracy and agreement in engineering surface measurement. The concept of “surface texture design” is also suggested, which involves designing the engineering surface texture, the manufacturing process, and the quality control procedure to meet the optimal functional needs. PMID:28184115

  15. Surface Sulfonation of Polyvinyl Chloride by Plasma for Antithrombogenicity

    NASA Astrophysics Data System (ADS)

    Liu, Peng; Chen, Yashao

    2004-06-01

    To enhance the blood compatibility of Polyvinyl Chloride (PVC) film, the film was modified by SO2/O2 gas plasma treatment. The effect of surface sulfonation of PVC treated by various SO2/O2 gas plasma depended on the volume ratio O2/(SO2 + O2). When the volume ratio was 0.5, the effect of sulfonation was the best. Sulfonic acid groups were specifically and efficiently introduced onto the PVC surface, which was proved by x-ray photoelectron spectroscopy (XPS) and Attenuated Total Reflectance Fourier Transfer Infrared (ATR-FTIR) spectroscopy. The surface microstructure of modified PVC film was studied with scanning electron microscopy (SEM). The antithrombogenicity of the samples was determined by the activated partial thromboplastin time (APTT), prothrombin time (PT), thrombin time (TT) and plasma recalcification time (PRT) tests and platelet adhesion experiment. The results indicated that the antithrombogenicity of modified PVC was improved remarkably.

  16. Topographies of plasma-hardened surfaces of poly(dimethylsiloxane)

    SciTech Connect

    Goerrn, Patrick; Wagner, Sigurd

    2010-11-15

    We studied the formation of surface layers hardened by plasma-enhanced oxidation of the silicone elastomer poly(dimethylsiloxane). We explored the largest parameter space surveyed to date. The surface layers may wrinkle, crack, or both, under conditions that at times are controlled by design, but more often have been discovered by trial-and-error. We find four distinct topographies: flat/wrinkled/cracked/cracked and wrinkled. Each topography is clearly separated in the space of plasma dose versus plasma pressure. We analyzed wrinkle amplitude and wavelength by atomic force microscopy in the tapping mode. From these dimensions we calculated the elastic modulus and thickness of the hard surface layer, and inferred a graded hardness, by employing a modified theoretical model. Our main result is the identification of the parameters under which the technologically important pure wrinkled, crack-free topography is obtained.

  17. Surface Waves and Landau Resonant Heating in Unmagnetized Bounded Plasmas

    NASA Astrophysics Data System (ADS)

    Bowers, Kevin

    2001-10-01

    Owing to the large areas and high plasma densities found in some recently developed devices [1], electrostatic theories of plasma resonances and surface wave [2-3] propagation in such devices are suspect as the size of the device is much larger than the free space wavelength associated with the peak plasma frequency. Accordingly, an electromagnetic model of surface wave propagation has been developed appropriate for large area plasmas. The predicted wave dispersion of the two models differs for extremely long wavelengths but is degenerate in devices small compared with wavelength. First principles particle-in-cell simulations using new techniques developed for the demanding simulation regime have been conducted which support these results. Given the slow wave character and boundary localized fields of surface waves, a periodic electrode may be used to resonantly excite a strong wave-particle interaction between surface waves and electrons. At saturation, the electron velocity distribution is enhanced above the phase velocity of the applied wave and suppressed below. The use of this technique (``Landau resonant heating'') to selectively heat the electron high energy tail to enhance electron-impact ionization is demonstrated using particle-in-cell simulation. [1] Matsumoto (Sumitomo Metal Industries). Private Communication. July 1999. [2] Nickel, Parker, Gould. Phys. Fluids. 7:1489. 1964. [3] Cooperberg. Phys. Plasmas. Vol. 5, No. 4, April 1998.

  18. Stability of plasma treated superhydrophobic surfaces under different ambient conditions.

    PubMed

    Chen, Faze; Liu, Jiyu; Cui, Yao; Huang, Shuai; Song, Jinlong; Sun, Jing; Xu, Wenji; Liu, Xin

    2016-05-15

    Plasma hydrophilizing of superhydrophobic substrates has become an important area of research, for example, superhydrophobic-(super)hydrophilic patterned surfaces have significant practical applications such as lab-on-chip systems, cell adhesion, and control of liquid transport. However, the stability of plasma-induced hydrophilicity is always considered as a key issue since the wettability tends to revert back to the untreated state (i.e. aging behavior). This paper focuses on the stability of plasma treated superhydrophobic surface under different ambient conditions (e.g. temperature and relative humidity). Water contact angle measurement and X-ray photoelectron spectroscopy are used to monitor the aging process. Results show that low temperature and low relative humidity are favorable to retard the aging process and that pre-storage at low temperature (-10°C) disables the treated surface to recover superhydrophobicity. When the aging is performed in water, a long-lasting hydropholicity is obtained. As the stability of plasma-induced hydrophilcity over a desired period of time is a very important issue, this work will contribute to the optimization of storage conditions of plasma treated superhydrophobic surfaces.

  19. Rapid surface treatment of polyamide 12 by microwave plasma jet

    NASA Astrophysics Data System (ADS)

    Hnilica, J.; Potočňáková, L.; Stupavská, M.; Kudrle, V.

    2014-01-01

    Polyamide 12 (PA 12) films were plasma treated using a microwave surface wave jet at atmospheric pressure. The parameters were the treatment time and the gas composition (argon or argon with admixtures). Moreover, the influence of power modulation was studied. It was found that significant change in wettability is achieved very rapidly, after only 25 ms of treatment. Plasma-induced surface changes are discussed using AFM, ATR-FTIR and XPS results. It is concluded that the increase in wettability is caused by both chemical and morphological changes.

  20. Charge fluctuations for particles on a surface exposed to plasma

    SciTech Connect

    Sheridan, T. E.; Hayes, A.

    2011-02-28

    We develop a stochastic model for the charge fluctuations on a microscopic dust particle resting on a surface exposed to plasma. We find in steady state that the fluctuations are normally distributed with a standard deviation that is proportional to (CT{sub e}){sup 1/2}, where C is the particle-surface capacitance and T{sub e} is the plasma electron temperature. The time for an initially uncharged ensemble of particles to reach the steady state distribution is directly proportional to CT{sub e}.

  1. Integrating Surface Modeling into the Engineering Design Graphics Curriculum

    ERIC Educational Resources Information Center

    Hartman, Nathan W.

    2006-01-01

    It has been suggested there is a knowledge base that surrounds the use of 3D modeling within the engineering design process and correspondingly within engineering design graphics education. While solid modeling receives a great deal of attention and discussion relative to curriculum efforts, and rightly so, surface modeling is an equally viable 3D…

  2. Lithium Surface Coatings and Improved Plasma Performance in NSTX

    NASA Astrophysics Data System (ADS)

    Kugel, H. W.

    2007-11-01

    NSTX research on lithium-coated plasma facing components is the latest step in a decade-long, multi-institutional research program to develop lithium as a plasma-facing system that can withstand the high heat and neutron fluxes in a DT reactor. The NSTX research is also aimed towards sustaining the current non- inductively in H-mode plasmas which requires control of both wall recycling and impurity influxes. Employing several techniques to coat the plasma facing components (PFCs) with lithium, NSTX experiments have shown, for the first time, significant benefits in high-power divertor plasmas. Lithium pellet injection (LPI) uses the plasma itself to distribute lithium on the divertor or limiter surfaces. The multi-barrel LPI on NSTX can introduce either lithium pellets with masses 1 - 5 mg or powder during a discharge. This significantly lowered recycling and reduced the density in a subsequent NBI-heated, divertor plasma. Lithium coatings have also been applied with a LIThium EvaporatoR (LITER) that was installed on an upper vacuum vessel port to direct a collimated stream of lithium vapor toward the graphite tiles of the lower center stack and divertor. The lithium was evaporated either before tokamak discharges, or continuously between and during them. By evaporating lithium into the helium glow discharge that typically precedes each tokamak discharge, a coating of the entire PFC area was achieved. Lithium depositions from a few mg to 1 g have been applied between discharges. Among the effects observed in subsequent neutral-beam heated plasmas were decreases in oxygen impurities, plasma density, and the inductive flux consumption, and increases in electron temperature, ion temperature, energy confinement and DD neutron rate. In addition, a reduction in the ELM frequency, including their complete suppression, was achieved in H-mode plasmas. Additional observations, such as, the duration of the lithium coatings, increases in core metal impurity radiation, and

  3. Plasma generation for controlled microwave-reflecting surfaces in plasma antennas

    SciTech Connect

    Bliokh, Yury P.; Felsteiner, Joshua; Slutsker, Yakov Z.

    2014-04-28

    The idea of replacing metal antenna elements with equivalent plasma objects has long been of interest because of the possibility of switching the antenna on and off. In general, two kinds of designs have so far been reported: (a) Separate plasma “wires” which are thin glass tubes filled with gas, where plasma appears due to discharge inside. (b) Reflecting surfaces, consisting of tightly held plasma wires or specially designed large discharge devices with magnetic confinement. The main disadvantages of these antennas are either large weight and size or too irregular surfaces for proper reflection. To design a microwave plasma antenna in the most common radar wavelength range of 1–3 cm with a typical gain of 30 dB, a smooth plasma mirror having a 10–30 cm diameter and a proper curvature is required. The plasma density must be 10{sup 12}–10{sup 14} cm{sup −3} in order to exceed the critical density for the frequency of the electromagnetic wave. To achieve this we have used a ferromagnetic inductively coupled plasma (FICP) source, where a thin magnetic core of a large diameter is fully immersed in the plasma. In the present paper, we show a way to adapt the FICP source for creating a flat switchable microwave plasma mirror with an effective diameter of 30 cm. This mirror was tested as a microwave reflector and there was found no significant difference when compared with a copper plate having the same diameter.

  4. Pharmaceutical and biomedical applications of surface engineered carbon nanotubes.

    PubMed

    Mehra, Neelesh Kumar; Jain, Keerti; Jain, Narendra Kumar

    2015-06-01

    Surface engineered carbon nanotubes (CNTs) are attracting recent attention of scientists owing to their vivid biomedical and pharmaceutical applications. The focus of this review is to highlight the important role of surface engineered CNTs in the highly challenging but rewarding area of nanotechnology. The major strength of this review lies in highlighting the exciting applications of CNTs to boost the research efforts, which unfortunately are otherwise scattered in the literature making the reading non-coherent and non-homogeneous.

  5. Plasma functionalized surface of commodity polymers for dopamine detection

    NASA Astrophysics Data System (ADS)

    Fabregat, Georgina; Osorio, Joaquin; Castedo, Alejandra; Armelin, Elaine; Buendía, Jorge J.; Llorca, Jordi; Alemán, Carlos

    2017-03-01

    We have fabricated potentially generalizable sensors based on polymeric-modified electrodes for the electrochemical detection of dopamine. Sensitive and selective sensors have been successfully obtained by applying a cold-plasma treatment during 1-2 min not only to conducting polymers but also to electrochemically inert polymers, such as polyethylene, polypropylene, polyvinylpyrrolidone, polycaprolactone and polystyrene. The effects of the plasma in the electrode surface activation, which is an essential requirement for the dopamine detection when inert polymers are used, have been investigated using X-ray photoelectron spectroscopy. Results indicate that exposure of polymer-modified electrodes to cold-plasma produces the formation of a large variety of reactive species adsorbed on the electrode surface, which catalyse the dopamine oxidation. With this technology, which is based on the application of a very simple physical functionalization, we have defined a paradox-based paradigm for the fabrication of electrochemical sensors by using inert and cheap plastics.

  6. Surface Modification of Medical Polyurethane by Plasma Treatment

    NASA Astrophysics Data System (ADS)

    Li, Dejun; Zhao, Jie; Gu, Hanqing; Lu, Mozhu; Ding, Fuqing; Hu, Jianfang

    1992-02-01

    The wettability and surface structure of plasma treatment on medical polyurethane were studied. Two kinds of gas, N2, Ar, were used to create the low-temperature plasma under low pressure. The wettability was investigated by means of the sessile drop method using water, the results show that the contact angle of water decreases from 78.8° to 61.9° as the treatment time increases. The results of electron spectroscopy for chemical analysis indicate that original chemical bonds were broken up after plasma treatment, which was the main reason for the surface modification. At same time, the results of electron spinning resonance show that the amounts of radicals did not increase significantly after treatment, which is advantageous to clinical practice of polyurethane.

  7. First international conference on surface engineering

    SciTech Connect

    Bucklow, I.A.

    1986-01-01

    This book contains 12 papers. Some of the titles are: Applications of electroslag cladding; Study on the cutting of self-fluxing alloy by CBN tools; Nickel alloy hardfacing of stainless steel: Present state and future perspective on surfacing rolling mill rolls in Czechoslovakia; and The use of solid state MIG power supply for wear-resistant alloy surfacing.

  8. Surface plasmon oscillations on a quantum plasma half-space

    SciTech Connect

    Moradi, Afshin

    2015-01-15

    We investigate the propagation of surface electrostatic oscillations on a quantum plasma half-space, taking into account the quantum effects. We derive the quantum surface wave frequencies of the system, by means the quantum hydrodynamic theory in conjunction with the Poisson equation and applying the appropriate additional quantum boundary conditions. Numerical results show in the presence of the slow nonlocal variations, plasmon wave energies of the system are significantly modified and plasmonic oscillations with blue-shifted frequencies emerge.

  9. Surface cleaning for enhanced adhesion to packaging surfaces: Effect of oxygen and ammonia plasma

    SciTech Connect

    Gaddam, Sneha; Dong, Bin; Driver, Marcus; Kelber, Jeffry; Kazi, Haseeb

    2015-03-15

    The effects of direct plasma chemistries on carbon removal from silicon nitride (SiN{sub x}) and oxynitride (SiO{sub x}N{sub y}) surfaces have been studied by in-situ x-ray photoelectron spectroscopy (XPS) and ex-situ contact angle measurements. The data indicate that O{sub 2} and NH{sub 3} capacitively coupled plasmas are effective at removing adventitious carbon from silicon nitride (SiN{sub x}) and Si oxynitride (SiO{sub x}N{sub y}) surfaces. O{sub 2} plasma treatment results in the formation of a silica overlayer. In contrast, the exposure to NH{sub 3} plasma results in negligible additional oxidation of the SiN{sub x} or SiO{sub x}N{sub y} surface. Ex-situ contact angle measurements show that SiN{sub x} and SiO{sub x}N{sub y} surfaces exposed to oxygen plasma are initially more hydrophilic than surfaces exposed to NH{sub 3} plasma, indicating that the O{sub 2} plasma-induced SiO{sub 2} overlayer is highly reactive toward ambient. At longer ambient exposures (≳10 h), however, surfaces treated by either O{sub 2} or NH{sub 3} plasma exhibit similar steady state contact angles, correlated with rapid uptake of adventitious carbon, as determined by XPS. Surface passivation by exposure to molecular hydrogen prior to ambient exposure significantly retards the increase in contact angle upon exposure to ambient. The results suggest a practical route to enhancing the time available for effective bonding to surfaces in microelectronics packaging applications.

  10. Two-surface wave decay: Controlling power transfer in plasma-surface interactions

    SciTech Connect

    Akimov, Yu. A.; Ostrikov, K.; Azarenkov, N. A.

    2007-08-15

    Controlled interaction of high-power pulsed electromagnetic radiation with plasma-exposed solid surfaces is a major challenge in applications spanning from electron beam accelerators in microwave electronics to pulsed laser ablation-assisted synthesis of nanomaterials. It is shown that the efficiency of such interaction can be potentially improved via an additional channel of wave power dissipation due to nonlinear excitation of two counterpropagating surface waves, resonant excitations of the plasma-solid system.

  11. Surface erosion caused on Mars from Viking descent engine plume

    NASA Technical Reports Server (NTRS)

    Hutton, R. E.; Moore, H. J.; Scott, R. F.; Shorthill, R. W.; Spitzer, C. R.

    1980-01-01

    During the Martian landings the descent engine plumes on Viking Lander 1 (VL-1) and Viking Lander 2 (VL-2) eroded the Martian surface materials. This had been anticipated and investigated both analytically and experimentally during the design phase of the Viking spacecraft. This paper presents data on erosion obtained during the tests of the Viking descent engine and the evidence for erosion by the descent engines of VL-1 and VL-2 on Mars. From these and other results, it is concluded that there are four distinct surface materials on Mars: (1) drift materials, (2) crusty to cloddy material, (3) blocky material, and (4) rock.

  12. Surface erosion caused on Mars from Viking descent engine plume

    USGS Publications Warehouse

    Hutton, R.E.; Moore, H.J.; Scott, R.F.; Shorthill, R.W.; Spitzer, C.R.

    1980-01-01

    During the Martian landings the descent engine plumes on Viking Lander 1 (VL-1) and Viking Lander 2 (VL-2) eroded the Martian surface materials. This had been anticipated and investigated both analytically and experimentally during the design phase of the Viking spacecraft. This paper presents data on erosion obtained during the tests of the Viking descent engine and the evidence for erosion by the descent engines of VL-1 and VL-2 on Mars. From these and other results, it is concluded that there are four distinct surface materials on Mars: (1) drift material, (2) crusty to cloddy material, (3) blocky material, and (4) rock. ?? 1980 D. Reidel Publishing Co.

  13. Surface Modification by Atmospheric Pressure Plasma for Improved Bonding

    NASA Astrophysics Data System (ADS)

    Williams, Thomas Scott

    An atmospheric pressure plasma source operating at temperatures below 150?C and fed with 1.0-3.0 volume% oxygen in helium was used to activate the surfaces of the native oxide on silicon, carbon-fiber reinforced epoxy composite, stainless steel type 410, and aluminum alloy 2024. Helium and oxygen were passed through the plasma source, whereby ionization occurred and ˜10 16 cm-3 oxygen atoms, ˜1015 cm -3 ozone molecules and ˜1016 cm-3 metastable oxygen molecules (O21Deltag) were generated. The plasma afterglow was directed onto the substrate material located 4 mm downstream. Surface properties of the plasma treated materials have been investigated using water contact angle (WCA), atomic force microscopy (AFM), infrared spectroscopy (IR), and x-ray photoelectron spectroscopy (XPS). The work presented herein establishes atmospheric-pressure plasma as a surface preparation technique that is well suited for surface activation and enhanced adhesive bond strength in a variety of materials. Atmospheric plasma activation presents an environmentally friendly alternative to wet chemical and abrasive methods of surface preparation. Attenuated total internal reflection infrared spectroscopy was used to study the aging mechanism of the native oxide on silicon. During storage at ambient conditions, the water contact angle of a clean surface increased from <5° to 40° over a period of 12 hours. When stored under a nitrogen purge, the water contact angle of a clean surface increased from <5° to 30° over a period of 40-60 hours. The change in contact angle resulted from the adsorption of nonanal onto the exposed surface hydroxyl groups. The rate of adsorption of nonanal under a nitrogen purged atmosphere ranged from 0.378+/-0.011 hr-1 to 0.182+/-0.008 hr -1 molecules/(cm2•s), decreasing as the fraction of hydrogen-bonded hydroxyl groups increased from 49% to 96% on the SiO 2 surface. The adsorption of the organic contaminant could be suppressed indefinitely by storing the

  14. Solitary surface waves on a magnetized plasma cylinder

    NASA Astrophysics Data System (ADS)

    Gradov, O. M.; Stenflo, L.; Sünder, D.

    1985-02-01

    We analyse high-frequency electrostatic solitary surface waves that propagate along a plasma cylinder in the presence of a constant axial magnetic field. The width of such a solitary wave, which is found to be inversely proportional to its amplitude, is expressed as a function of the magnitude of the external magnetic field.

  15. Solar Wind Plasma and UV effects on Surfaces in Space

    NASA Astrophysics Data System (ADS)

    Horanyi, M.

    2011-12-01

    Dust plasma interactions on airless bodies in space affect both the exposed surfaces and the plasma flow around them. For example, charging, evaporation, and sputtering can shape the spatial and size distributions of small dust particles, and simultaneously alter the composition and energy distribution of the solar wind flow. Recent Ulysses observations of the temporal variability of the flux and direction of the interstellar dust flow show that the dynamics of submicron sized interplanetary and interstellar dust is determined by their charge and interactions with the large-scale structure of the heliospheric magnetic fields. Future observations by the Solar Probe Plus mission near the Sun are expected to identify pick-up ions from the evaporation and sputtering of dust and the effects of mass-loading on the solar wind. Charging of surfaces, combined with near-surface electric fields can lead to the mobilization and transport of small charged dust particles on all airless bodies in the solar system. Halley's comet showed large brightness fluctuations on very short time-scales at distances well beyond 8 AU. Surface charging due to intermittent high-speed solar wind streams have been suggested to be responsible for lofting small grains, increasing the effective surface area of the dormant nucleus. Images taken of the surface of asteroid Eros indicated the accumulation of fine dust in craters, possibly due to electrostatic dust transport. Remote sensing and in situ observations indicating dust transport on the Moon date back to the Apollo era and remain highly controversial. This presentation, motivated by existing observations, will describe a series of small-scale laboratory experiments and supporting theory to investigate dust charging, the properties of photoelectron sheaths, and the emergence of intense electric fields near boundaries of lit and dark surfaces, and regions shielded and exposed to the solar wind plasma flow. The Moon is the nearest place where

  16. Proteomic characterization of engineered nanomaterial-protein interactions in relation to surface reactivity.

    PubMed

    Sund, Jukka; Alenius, Harri; Vippola, Minnamari; Savolainen, Kai; Puustinen, Anne

    2011-06-28

    Adsorption of proteins onto an engineered nanoparticle surface happens immediately after particles come in contact with a biological fluid. However, at the moment very little is known about the mechanisms of interactions between biomolecules and nanomaterials. In this study, eleven thoroughly characterized materials were first investigated in vitro for their ability to enter human lung epithelial cells and human monocyte-derived macrophages. All tested materials were taken up by primary macrophages and epithelial cells. Some of the engineered nanomaterials (ENM) were found in the cytoplasm. Large quantitative and qualitative variation in the binding efficiencies to cellular proteins was observed between different tested nanoparticles. Pulmonary surfactant components significantly reduced the overall protein adsorption on the surface of ENMs. Fibrinogen chains were attached to all materials after exposure to plasma proteins. Common ENM-bound cytoplasmic protein identifications were peroxiredoxin 1, annexin A2, and several ribosomal and cytoskeletal proteins. The underlying mechanism of the ENM-plasma protein interaction may diverge from that of cell lysate proteins, as the binding efficiency to cell lysate proteins appears to depend on the characteristics of the ENM surface, whereas the adsorbed plasma proteins are involved in particle phagocytosis and seem to cover ENMs independently of the their surface properties. Identification of the composition of the nanomaterial-protein complex is crucial for understanding of the uptake mechanisms, biodistribution, and clearance of ENMs, knowledge which is required for safety evaluation and biomedical applications of these materials.

  17. Helium atmospheric pressure plasma jets touching dielectric and metal surfaces

    SciTech Connect

    Norberg, Seth A. Johnsen, Eric; Kushner, Mark J.

    2015-07-07

    Atmospheric pressure plasma jets (APPJs) are being investigated in the context plasma medicine and biotechnology applications, and surface functionalization. The composition of the surface being treated ranges from plastics, liquids, and biological tissue, to metals. The dielectric constant of these materials ranges from as low as 1.5 for plastics to near 80 for liquids, and essentially infinite for metals. The electrical properties of the surface are not independent variables as the permittivity of the material being treated has an effect on the dynamics of the incident APPJ. In this paper, results are discussed from a computational investigation of the interaction of an APPJ incident onto materials of varying permittivity, and their impact on the discharge dynamics of the plasma jet. The computer model used in this investigation solves Poisson's equation, transport equations for charged and neutral species, the electron energy equation, and the Navier-Stokes equations for the neutral gas flow. The APPJ is sustained in He/O{sub 2} = 99.8/0.2 flowing into humid air, and is directed onto dielectric surfaces in contact with ground with dielectric constants ranging from 2 to 80, and a grounded metal surface. Low values of relative permittivity encourage propagation of the electric field into the treated material and formation and propagation of a surface ionization wave. High values of relative permittivity promote the restrike of the ionization wave and the formation of a conduction channel between the plasma discharge and the treated surface. The distribution of space charge surrounding the APPJ is discussed.

  18. Lunar surface engineering properties experiment definition

    NASA Technical Reports Server (NTRS)

    Mitchell, J. K.; Goodman, R. E.; Hurlbut, F. C.; Houston, W. N.; Willis, D. R.; Witherspoon, P. A.; Hovland, H. J.

    1971-01-01

    Research on the mechanics of lunar soils and on developing probes to determine the properties of lunar surface materials is summarized. The areas of investigation include the following: soil simulation, soil property determination using an impact penetrometer, soil stabilization using urethane foam or phenolic resin, effects of rolling boulders down lunar slopes, design of borehole jack and its use in determining failure mechanisms and properties of rocks, and development of a permeability probe for measuring fluid flow through porous lunar surface materials.

  19. Molecular engineering of semiconductor surfaces and devices.

    PubMed

    Ashkenasy, Gonen; Cahen, David; Cohen, Rami; Shanzer, Abraham; Vilan, Ayelet

    2002-02-01

    Grafting organic molecules onto solid surfaces can transfer molecular properties to the solid. We describe how modifications of semiconductor or metal surfaces by molecules with systematically varying properties can lead to corresponding trends in the (electronic) properties of the resulting hybrid (molecule + solid) materials and devices made with them. Examples include molecule-controlled diodes and sensors, where the electrons need not to go through the molecules (action at a distance), suggesting a new approach to molecule-based electronics.

  20. Surface Structure and Surface Electronic States Related to Plasma Cleaning of Silicon and Germanium

    NASA Astrophysics Data System (ADS)

    Cho, Jaewon

    This thesis discusses the surface structure and the surface electronic states of Si and Ge(100) surfaces as well as the effects of oxidation process on the silicon oxide/Si(100) interface structure. The H-plasma exposure was performed in situ at low temperatures. The active species, produced in the H-plasma by the rf-excitation of H_2 gas, not only remove microcontaminants such as oxygen and carbon from the surface, but also passivate the surface with atomic hydrogen by satisfying the dangling bonds of the surface atoms. The surfaces were characterized by Angle Resolved UV-Photoemission Spectroscopy (ARUPS) and Low Energy Electron Diffraction (LEED). In the case of Si(100), H-plasma exposure produced ordered H-terminated crystallographic structures with either a 2 x 1 or 1 x 1 LEED pattern. The hydride phases, found on the surfaces of the cleaned Si(100), were shown to depend on the temperature of the surface during H-plasma cleaning. The electronic states for the monohydride and dihydride phases were identified by ARUPS. When the plasma cleaned surface was annealed, the phase transition from the dihydride to monohydride was observed. The monohydride Si-H surface bond was stable up to 460^circC, and the dangling bond surface states were identified after annealing at 500^circC which was accompanied by the spectral shift. The H-terminated surface were characterized to have a flat band structure. For the Ge(100) surface, an ordered 2 x 1 monohydride phase was obtained from the surface cleaned at 180 ^circC. After plasma exposure at <=170^circC a 1 x 1 surface was observed, but the ARUPS indicated that the surface was predominantly composed of disordered monohydride structures. After annealing above the H-dissociation temperatures, the shift in the spectrum was shown to occur with the dangling bond surface states. The H-terminated surfaces were identified to be unpinned. The interface structure of silicon oxide/Si(100) was studied using ARUPS. Spectral shifts were

  1. Surface modification of tube inner wall by transferred atmospheric pressure plasma

    NASA Astrophysics Data System (ADS)

    Chen, Faze; Liu, Shuo; Liu, Jiyu; Huang, Shuai; Xia, Guangqing; Song, Jinlong; Xu, Wenji; Sun, Jing; Liu, Xin

    2016-12-01

    Tubes are indispensable in our daily life, mechanical engineering and biomedical fields. However, the practical applications of tubes are sometimes limited by their poor wettability. Reported herein is hydrophilization of the tube inner wall by transferred atmospheric pressure plasma (TAPP). An Ar atmospheric pressure plasma jet (APPJ) is used to induce He TAPP inside polytetrafluoroethylene (PTFE) tube to perform inner wall surface modification. Optical emission spectrum (OES) is used to investigate the distribution of active species, which are known as enablers for surface modification, along the TAPP. Tubes' surface properties demonstrate that after TAPP treatment, the wettability of the tube inner wall is well improved due to the decrease of surface roughness, the removal of surface fluorine and introduction of oxygen. Notably, a deep surface modification can significantly retard the aging of the obtained hydrophilicity. The results presented here clearly demonstrate the great potential of TAPP for surface modification of the inner wall of tube or other hollow bodies, and thus a uniform, effective and long-lasting surface modification of tube with any length can be easily realized by moving the tube along its axis.

  2. Lubrication of engineering surfaces - II. Final report

    SciTech Connect

    McCool, J.I.

    1983-12-01

    The focus of the work was to improve the state-of-the-art of performance prediction for rolling/sliding contacts in terms of the statistical microgeometry of the contacting bodies and the properties of the fluid medium that separates the surfaces. The work was divided into several interrelated areas: development of an asperity contact model that accounts for the inherent directionality (anisotropy) that typifies real surfaces and that specifically reflects the effect of frequency content of the roughness process; development of guidelines for preprocessing (filtering) roughness data and for assessing the distortional effect of stylus radius and flight, record length, sampling rate and quantization error on the generalized surface characterization required by the contact model; delineate the limitations of the assumptions of mechanical and statistical independence and gaussianity, inherent in asperity contact models and the limitations of modelling asperity shapes as 2nd order polynomials; development and experimental validation of a combined fluid/coulomb model for predicting the traction transmitted when real surfaces undergo relative rolling and sliding in the important regime where the lubricant film is thin enough to permit some degree of asperity contact; and generation and compilation of lubricant and surface roughness data required for contact performance prediction and quantification of the statistical error inherent in surface characterizations.

  3. Lubrication of engineering surfaces - II. Final report

    SciTech Connect

    Mc Cool, J.I.

    1983-12-01

    The focus of the work was to improve the state-of-the-art of performance prediction for rolling/sliding contacts in terms of the statistical microgeometry of the contacting bodies and the properties of the fluid medium that separates the surfaces. The work was divided into several interrelated areas: development of an asperity contact model that accounts for the inherent directionality (anisotropy) that typifies real surfaces and that specifically reflects the effect of frequency content of the roughness process; development of guidelines for preprocessing (filtering) roughness data and for assessing the distortional effect of stylus radius and flight, record length, sampling rate and quantization error on the generalized surface characterization required by the contact model; delineate the limitations of the assumptions of mechanical and statistical independence and gaussianity, inherent in asperity contact models and the limitations of modelling asperity shapes as 2nd order polynomials; development and experimental validation of a combined fluid/coulomb model for predicting the traction transmitted when real surfaces undergo relative rolling and sliding in the important regime where the lubricant film is thin enough to permit some degree of asperity contact; and generation and compilation of lubricant and surface roughness data required for contact performance prediction and quantification of the statistical error inherent in surface characterizations. To the extent that this work has been completed and reported, these reports or papers are included and synopsized. To the extent that the work is as yet unreported or otherwise incomplete, its status and plans for eventual completion are discussed.

  4. H-mode inductive coupling plasma for PVC surface treatment

    NASA Astrophysics Data System (ADS)

    Croccolo, F.; Quintini, A.; Barni, R.; Ripamonti, M.; Malgaroli, A.; Riccardi, C.

    2009-08-01

    An inductively coupled plasma machine has been modified to be able to apply working powers in the order of 1 kW, thus switching to the real inductive H-mode. The plasma is generated by applying a 13.56 MHz radio-frequency to a λ/4 antenna outside the plasma chamber in low pressure conditions. The working gas is argon at pressure in the range from 10 to 100 Pa. With this high power source we have been able to perform plasma etching on a poly(vinyl-chloride) (PVC) film. In particular the effect of the plasma is the selective removal of hydrogen and chlorine from the sample surface. The action of the high power plasma on the sample has been proved to be much more effective than that of the low power one. Results similar to those obtained with the low power machine at about 300 W for 120 min, have been obtained with the high power source at about 600 W for 30 min. The superficial generation of a conductive layer of double C=C bonds was obtained. The samples have been investigated by means of ATR spectroscopy, FIB/SEM microscopy and micro-electrical measurements, which revealed the change in charge conductivity.

  5. Plasma Surface Modification for Immobilization of Bone Morphogenic Protein-2 on Polycaprolactone Scaffolds

    NASA Astrophysics Data System (ADS)

    Kim, Byung Hoon; Myung, Sung Woon; Jung, Sang Chul; Ko, Yeong Mu

    2013-11-01

    The immobilization of recombinant human bone formation protein-2 (rhBMP-2) on polycaprolactone (PCL) scaffolds was performed by plasma polymerization. RhBMP-2, which induces osteoblast differentiation in various cell types, is a growth factor that plays an important role in bone formation and repair. The surface of the PCL scaffold was functionalized with the carboxyl groups of plasma-polymerized acrylic acid (PPAA) thin films. Plasma polymerization was carried out at a discharge power of 60 W at an acrylic acid flow rate of 7 sccm for 5 min. The PPAA thin film exhibited moderate hydrophilic properties and possessed a high density of carboxyl groups. Carboxyl groups and rhBMP-2 on the PCL scaffolds surface were identified by attenuated total reflection Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy, respectively. The alkaline phosphatase activity assay showed that the rhBMP-2 immobilized PCL scaffold increased the level of MG-63 cell differentiation. Plasma surface modification for the preparation of biomaterials, such as biofunctionalized polymer scaffolds, can be used for the binding of bioactive molecules in tissue engineering.

  6. Experimental Study on Plasma Surface Treatment of Capacitors Film

    NASA Astrophysics Data System (ADS)

    Ling, Dai; Ting, Yin; Fuchang, Lin; Fei, Yan

    Plasma surface treatment is an optional way to change the electrical performance of the film capacitors used widely in pulse power application. This paper presents the experimental study of glow discharge plasma treatment to polyphenylene sulfide (PPS) film. By using infrared spectra and scanning electron microscope (SEM), the chemical component and microstructure of material surface has detected to be changed with different treatment strength and various discharge gas. After treatment, the film surface tends to be rougher and some sorts of polar radicals or groups found to be introduced. But there is no obvious change of the electrical strength of the film. At last, theoretical analysis has been carried out with polypropylene film experimental treatment results in author's former work.

  7. Coil Tolerance Impact on Plasma Surface Quality for NCSX

    SciTech Connect

    Art Brooks; Wayne Reiersen

    2003-10-20

    The successful operation of the National Compact Stellarator Experiment (NCSX) machine will require producing plasma configurations with good flux surfaces, with a minimum volume of the plasma lost to magnetic islands or stochastic regions. The project goal is to achieve good flux surfaces over 90% of the plasma volume. NCSX is a three period device designed to be operated with iota ranging from {approx}0.4 on axis to {approx}0.7 at the edge. The field errors of most concern are those that are resonant with 3/5 and 3/6 modes (for symmetry preserving field errors) and the 1/2 and 2/3 modes (for symmetry breaking field errors). In addition to losses inherent in the physics configuration itself, there will be losses from field errors arising from coil construction and assembly errors. Some of these losses can be recovered through the use of trim coils or correction coils. The impact of coil tolerances on plasma surface quality is evaluated herein for the NCSX design. The methods used in this evaluation are discussed. The ability of the NCSX trim coils to correct for field errors is also examined. The results are used to set coils tolerances for the various coil systems.

  8. Universal self-amplification channel for surface plasma waves

    NASA Astrophysics Data System (ADS)

    Deng, Hai-Yao; Wakabayashi, Katsunori; Lam, Chi-Hang

    2017-01-01

    We present a theory of surface plasma waves (SPWs) in metals with arbitrary electronic collision rate τ-1. We show that there exists a universal intrinsic amplification channel for these waves, subsequent to the interplay between ballistic motions and the metal surface. We evaluate the corresponding amplification rate γ0, which turns out to be a sizable fraction of the SPW frequency ωs. We also find that the value of ωs depends on surface scattering properties, in contrast with the conventional theory.

  9. Response of nickel surface to pulsed fusion plasma radiations

    SciTech Connect

    Niranjan, Ram Rout, R. K. Srivastava, R. Gupta, Satish C.; Chakravarthy, Y.; Patel, N. N.; Alex, P.

    2014-04-24

    Nickel based alloys are being projected as suitable materials for some components of the next generation fusion reactor because of compatible thermal, electrical and mechanical properties. Pure nickel material is tested here for possibility of similar application purpose. Nickel samples (> 99.5 % purity) are exposed here to plasma radiations produced due to D-D fusion reaction inside an 11.5 kJ plasma focus device. The changes in the physical properties of the nickel surface at microscopic level which in turn change the mechanical properties are analyzed using scanning electron microscope, optical microscope, glancing incident X-ray diffractometer and Vicker's hardness gauge. The results are reported here.

  10. Response of nickel surface to pulsed fusion plasma radiations

    NASA Astrophysics Data System (ADS)

    Niranjan, Ram; Rout, R. K.; Srivastava, R.; Chakravarthy, Y.; Patel, N. N.; Alex, P.; Gupta, Satish C.

    2014-04-01

    Nickel based alloys are being projected as suitable materials for some components of the next generation fusion reactor because of compatible thermal, electrical and mechanical properties. Pure nickel material is tested here for possibility of similar application purpose. Nickel samples (> 99.5 % purity) are exposed here to plasma radiations produced due to D-D fusion reaction inside an 11.5 kJ plasma focus device. The changes in the physical properties of the nickel surface at microscopic level which in turn change the mechanical properties are analyzed using scanning electron microscope, optical microscope, glancing incident X-ray diffractometer and Vicker's hardness gauge. The results are reported here.

  11. Plasma Surface Modification of Polyaramid Fibers for Protective Clothing

    NASA Astrophysics Data System (ADS)

    Widodo, Mohamad

    2011-12-01

    The purpose of this research was to develop a novel process that would achieve biocidal properties on Kevlar fabric via atmospheric pressure plasma jet (APPJ) induced-graft polymerization of monomers. In the course of the study, experiments were carried out to understand plasma-monomer-substrate interactions, particularly, how each of the main parameters in the plasma processing affects the formation of surface radicals and eventually the degree of graft polymerization of monomers. The study also served to explore the possibility of developing plasma-initiated and plasma-controlled graft polymerization for continuous operation. In this regards, three methods of processing were studied, which included two-step plasma graft-polymerization with immersion, two-step and one-step plasma graft-polymerization with pad-dry. In general, plasma treatment did not cause visible damage to the surface of Kevlar fibers, except for the appearance of tiny globules distributed almost uniformly indicating a minor effect of plasma treatment to the surface morphology of the polymer. From the examination of SEM images, however, it was found that a very localized surface etching seemed to have taken place, especially at high RF power (800 W) and long time of exposure (60 s), even in plasma downstream mode of operation. It was suggested that a small amount of charged particles might have escaped and reached the substrate surface. High density of surface radicals, which is the prerequisite for high graft density and high antimicrobial activity, was achieved by the combination of high RF power and short exposure time or low RF power and long time of exposure. This was a clear indication that the formation of surface radicals is a function of amount of the dissipated energy, which also explained the two-factor interaction between the two process parameters. XPS results showed that hydrolysis of the anilide bond of PPTA chains took place to some extent on the surface of Kevlar, leading to the

  12. Fibrinogen adsorption and host tissue responses to plasma functionalized surfaces.

    PubMed

    Tang, L; Wu, Y; Timmons, R B

    1998-10-01

    The physical and chemical characteristics of material surfaces are thought to play important roles in biomaterial-mediated tissue responses. To understand the importance of discrete biomaterial chemical characteristics in modifying host tissue responses, we constructed surfaces bearing different functional groups using radio frequency glow discharge plasma polymerization. Surfaces evaluated included those having high concentrations of -OH, -NH2, -CF3, and siloxyl groups. These surfaces and polyethylene terephthalate controls were used to assess the importance of particular physicochemical characteristics in surface:protein:cell interactions both in vitro and in vivo. The results obtained show that surface functionalities do significantly affect both the adsorption and "denaturation" of adsorbed fibrinogen (which is an important mediator of inflammatory responses to biomaterial implants). In addition, these surfaces provoke different degrees of acute inflammatory responses. Interestingly, the amounts of "denatured" fibrinogen that spontaneously accumulate on the individual surfaces correlate closely with the extent of biomaterial-mediated inflammation. These results suggest that surfaces that tend to "irreversibly" bind fibrinogen prompt greater acute inflammatory responses. Unexpectedly, all test surfaces except those bearing a siloxyl group engender relatively similar biomaterial-mediated fibrotic responses. Thus surface functionalities alone may not be sufficient to affect subsequent fibrotic responses.

  13. Characteristics of surface sterilization using electron cyclotron resonance plasma

    NASA Astrophysics Data System (ADS)

    Yonesu, Akira; Hara, Kazufumi; Nishikawa, Tatsuya; Hayashi, Nobuya

    2016-07-01

    The characteristics of surface sterilization using electron cyclotron resonance (ECR) plasma were investigated. High-energy electrons and oxygen radicals were observed in the ECR zone using electric probe and optical emission spectroscopic methods. A biological indicator (BI), Geobacillus stearothermophilus, containing 1 × 106 spores was sterilized in 120 s by exposure to oxygen discharges while maintaining a temperature of approximately 55 °C at the BI installation position. Oxygen radicals and high-energy electrons were found to be the sterilizing species in the ECR region. It was demonstrated that the ECR plasma could be produced in narrow tubes with an inner diameter of 5 mm. Moreover, sterilization tests confirmed that the spores present inside the narrow tube were successfully inactivated by ECR plasma irradiation.

  14. Atmospheric-Pressure Plasma Cleaning of Contaminated Surfaces

    SciTech Connect

    Robert F. Hicks; Hans W. Herrmann

    2003-12-15

    The purpose of this project was to demonstrate a practical, environmentally benigh technology for the surface decontamination and decommissioning of radioactive waste. A low temperature, atmospheric pressure plasma has been developed with initial support from the DOE, Environmental Management Sciences Program. This devise selectively etches radioactive metals from surfaces, rendering objects radiation free and suitable for decommissioning. The volatile reaction products are captured on filters, which yields a tremendous reduction in the volume of the waste. The technology shows a great potential for accelerating the clean-up effort for the equipment and structures contaminated with radioactive materials within the DOE complex. The viability of this technology has been demonstrated by selectively and rapidly stripping uranium from stainless steel surfaces at low temperature. Studies on uranium oxide have shown that etch rates of 4.0 microns per minute can be achieved at temperature below 473 K. Over the past three years, we have made numerous improvements in the design of the atmospheric pressure plasma source. We are now able to scale up the plasma source to treat large surface areas.

  15. Diagnostics of plasma-biological surface interactions in low pressure and atmospheric pressure plasmas

    NASA Astrophysics Data System (ADS)

    Ishikawa, Kenji; Hori, Masaru

    2014-08-01

    Mechanisms of plasma-surface interaction are required to understand in order to control the reactions precisely. Recent progress in atmospheric pressure plasma provides to apply as a tool of sterilization of contaminated foodstuffs. To use the plasma with safety and optimization, the real time in situ detection of free radicals - in particular dangling bonds by using the electron-spin-resonance (ESR) technique has been developed because the free radical plays important roles for dominantly biological reactions. First, the kinetic analysis of free radicals on biological specimens such as fungal spores of Penicillium digitatum interacted with atomic oxygen generated plasma electric discharge. We have obtained information that the in situ real time ESR signal from the spores was observed and assignable to semiquinone radical with a g-value of around 2.004 and a line width of approximately 5G. The decay of the signal was correlated with a link to the inactivation of the fungal spore. Second, we have studied to detect chemical modification of edible meat after the irradiation. Using matrix-assisted laser desorption/ionization time-of-flight mass spectroscopy (MALDI-TOF-MS) and ESR, signals give qualification results for chemical changes on edible liver meat. The in situ real-time measurements have proven to be a useful method to elucidate plasma-induced surface reactions on biological specimens.

  16. Surface wave propagation in non-ideal plasmas

    NASA Astrophysics Data System (ADS)

    Pandey, B. P.; Dwivedi, C. B.

    2015-03-01

    The properties of surface waves in a partially ionized, compressible magnetized plasma slab are investigated in this work. The waves are affected by the non-ideal magnetohydrodynamic (MHD) effects which causes finite drift of the magnetic field in the medium. When the magnetic field drift is ignored, the characteristics of the wave propagation in a partially ionized plasma fluid is similar to the fully ionized ideal MHD except now the propagation properties depend on the fractional ionization as well as on the compressibility of the medium. The phase velocity of the sausage and kink waves increases marginally (by a few per cent) due to the compressibility of the medium in both ideal as well as Hall-diffusion-dominated regimes. However, unlike ideal regime, only waves below certain cut-off frequency can propagate in the medium in Hall dominated regime. This cut-off for a thin slab has a weak dependence on the plasma beta whereas for thick slab no such dependence exists. More importantly, since the cut-off is introduced by the Hall diffusion, the fractional ionization of the medium is more important than the plasma compressibility in determining such a cut-off. Therefore, for both compressible as well incompressible medium, the surface modes of shorter wavelength are permitted with increasing ionization in the medium. We discuss the relevance of these results in the context of solar photosphere-chromosphere.

  17. Nonthermal plasma technology as a versatile strategy for polymeric biomaterials surface modification: a review.

    PubMed

    Desmet, Tim; Morent, Rino; De Geyter, Nathalie; Leys, Christophe; Schacht, Etienne; Dubruel, Peter

    2009-09-14

    In modern technology, there is a constant need to solve very complex problems and to fine-tune existing solutions. This is definitely the case in modern medicine with emerging fields such as regenerative medicine and tissue engineering. The problems, which are studied in these fields, set very high demands on the applied materials. In most cases, it is impossible to find a single material that meets all demands such as biocompatibility, mechanical strength, biodegradability (if required), and promotion of cell-adhesion, proliferation, and differentiation. A common strategy to circumvent this problem is the application of composite materials, which combine the properties of the different constituents. Another possible strategy is to selectively modify the surface of a material using different modification techniques. In the past decade, the use of nonthermal plasmas for selective surface modification has been a rapidly growing research field. This will be the highlight of this review. In a first part of this paper, a general introduction in the field of surface engineering will be given. Thereafter, we will focus on plasma-based strategies for surface modification. The purpose of the present review is twofold. First, we wish to provide a tutorial-type review that allows a fast introduction for researchers into the field. Second, we aim to give a comprehensive overview of recent work on surface modification of polymeric biomaterials, with a focus on plasma-based strategies. Some recent trends will be exemplified. On the basis of this literature study, we will conclude with some future trends for research.

  18. Microscopic theory of electron absorption by plasma-facing surfaces

    NASA Astrophysics Data System (ADS)

    Bronold, F. X.; Fehske, H.

    2017-01-01

    We describe a method for calculating the probability with which the wall of a plasma absorbs an electron at low energy. The method, based on an invariant embedding principle, expresses the electron absorption probability as the probability for transmission through the wall’s long-range surface potential times the probability to stay inside the wall despite of internal backscattering. To illustrate the approach we apply it to a SiO2 surface. Besides emission of optical phonons inside the wall we take elastic scattering at imperfections of the plasma-wall interface into account and obtain absorption probabilities significantly less than unity in accordance with available electron-beam scattering data but in disagreement with the widely used perfect absorber model.

  19. Comparative study of NO removal in surface-plasma and volume-plasma reactors based on pulsed corona discharges.

    PubMed

    Malik, Muhammad Arif; Kolb, Juergen F; Sun, Yaohong; Schoenbach, Karl H

    2011-12-15

    Nitric oxide (NO) conversion has been studied for two different types of atmospheric-pressure pulsed-corona discharges, one generates a surface-plasma and the other provides a volume-plasma. For both types of discharges the energy cost for NO removal increases with decreasing oxygen concentration and initial concentration of NO. However, the energy cost for volume plasmas for 50% NO removal, EC(50), from air was found to be 120 eV/molecule, whereas for the surface plasma, it was only 70 eV/molecule. A smaller difference in energy cost, but a higher efficiency for removal of NO was obtained in a pure nitrogen atmosphere, where NO formation is restricted due to the lack of oxygen. For the volume plasma, EC(50) in this case was measured at 50 eV/molecule, and for the surface plasma it was 40 eV/molecule. Besides the higher NO removal efficiency of surface plasmas compared to volume plasmas, the energy efficiency of surface-plasmas was found to be almost independent of the amount of electrical energy deposited in the discharge, whereas the efficiency for volume plasmas decreases considerably with increasing energy. This indicates the possibility of operating surface plasma discharges at high energy densities and in more compact reactors than conventional volume discharges.

  20. Surface properties of native human plasma lipoproteins and lipoprotein models.

    PubMed Central

    Massey, J B; Pownall, H J

    1998-01-01

    Plasma lipoprotein surface properties are important but poorly understood determinants of lipoprotein catabolism. To elucidate the relation between surface properties and surface reactivity, the physical properties of surface monolayers of native lipoproteins and lipoprotein models were investigated by fluorescent probes of surface lipid fluidity, surface lateral diffusion, and interfacial polarity, and by their reactivity to Naja melanoleuca phospholipase A2 (PLA2). Native lipoproteins were human very low, low-, and subclass 3 high-density lipoproteins (VLDL, LDL, and HDL3); models were 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) or its ether analog in single-bilayer vesicles, large and small microemulsions of POPC and triolein, and reassembled HDL (apolipoprotein A-I plus phospholipid). Among lipoproteins, surface lipid fluidity increased in the order HDL3 < LDL < VLDL, varying inversely with their (protein + cholesterol)/phospholipid ratios. Models resembled VLDL in fluidity. Both lateral mobility in the surface monolayer and polarity of the interfacial region were lower in native lipoproteins than in models. Among native lipoproteins and models, increased fluidity in the surface monolayer was associated with increased reactivity to PLA2. Addition of cholesterol (up to 20 mol%) to models had little effect on PLA2 activity, whereas the addition of apolipoprotein C-III stimulated it. Single-bilayer vesicles, phospholipid-triolein microemulsions, and VLDL have surface monolayers that are quantitatively similar, and distinct from those of LDL and HDL3. Surface property and enzymatic reactivity differences between lipoproteins and models were associated with differences in surface monolayer protein and cholesterol contents. Thus differences in the surface properties that regulate lipolytic reactivity are a predictable function of surface composition. PMID:9533698

  1. Plasma wall interaction: Important ion induced surface processes and strategy of the EU Task Force

    NASA Astrophysics Data System (ADS)

    Roth, Joachim; Tsitrone, Emmanuelle; Loarte, Alberto

    2007-05-01

    In future thermo-nuclear fusion devices, such as ITER (International Thermonuclear Experimental Reactor), the interaction of the plasma with surrounding materials in the vacuum vessel constitutes one of the main remaining engineering problems. The choice of materials is a crucial point, which will determine issues such as the plasma facing components lifetime before refurbishment or the tritium inventory build up in the vessel, which should be limited for safety reasons. In order to tackle these issues, the European Task Force on Plasma-Wall Interaction has been implemented in the frame of EFDA (European Fusion Agreement) in the fall 2002 with the aim "to provide ITER with information concerning lifetime-expectations of the divertor target plates and tritium inventory build-up rates in the foreseen starting configuration and to suggest improvements, including material changes, which could be implemented at an appropriate stage." The EU-PWI-TF brings together the efforts of 24 European associations in the following fields of investigation: Material erosion and transport in tokamaks. Tritium inventory and removal. Transient heat loads on plasma facing components. Dust production and removal. Associated modelling and diagnostic development. This paper will present the organisation of the EU-PWI-TF. It will provide examples for the multitude of surface processes in Plasma-Wall Interaction and present the status of knowledge concerning material erosion and hydrogen retention for the choice of ITER materials (Beryllium, Carbon and Tungsten).

  2. Electrostatic surface waves on a plasma with non-uniform boundary

    NASA Astrophysics Data System (ADS)

    Stenflo, L.; Gradov, O. M.

    1990-10-01

    A new analytical method is introduced to consider electrostatic surface waves propagating on a cold plasma. A very simple dispersion relation is derived for a plasma bounded by two dielectrics. Previous theory for solitary surface waves is also generalized.

  3. Multisolitary plasma surface waves in the presence of an external pump field

    NASA Astrophysics Data System (ADS)

    Gradov, O. M.; Stenflo, L.

    1991-11-01

    It is shown that an external electromagnetic pump wave, which interacts with the electrostatic surface oscillations in a semi-infinite plasma with a sharp boundary, can excite a sequence of solitary waves on the plasma surface.

  4. Engineering the dispersion of metamaterial surface for broadband infrared absorption.

    PubMed

    Feng, Qin; Pu, Mingbo; Hu, Chenggang; Luo, Xiangang

    2012-06-01

    We propose a broadband infrared absorber by engineering the frequency dispersion of metamaterial surface (metasurface) to mimic an ideal absorbing sheet. With a thin layer of structured nichrome, a polarization-independent absorber with absorption larger than 97% is numerically demonstrated over a larger than one octave bandwidth. It is shown that the bandwidth enhancement is related with the transformation of the Drude model of free electron gas in metal film to the Lorentz oscillator model of a bound electron in the structured metallic surface. We believe that the concept of dispersion engineering may provide helpful guidance for the design of a broadband absorber.

  5. Current Density and Plasma Displacement Near Perturbed Rational Surface

    SciTech Connect

    A.H. Boozer and N. Pomphrey

    2010-10-10

    The current density in the vicinity of a rational surface of a force-free magnetic field subjected to an ideal perturbation is shown to be the sum of both a smooth and a delta-function distribution, which give comparable currents. The maximum perturbation to the smooth current density is comparable to a typical equilibrium current density and the width of the layer in which the current flows is shown to be proportional to the perturbation amplitude. In the standard linearized theory, the plasma displacement has an unphysical jump across the rational surface, but the full theory gives a continuous displacement.

  6. Surface platinum metal plasma resonance photonic crystal fiber sensor

    NASA Astrophysics Data System (ADS)

    Cui, Deyu; Chen, Heming; Bai, Xiuli

    2016-01-01

    A two rings, triangular lattice photonic crystal fiber sensor element using surface plasma resonance phenomenon is proposed. The performance of the sensor is analyzed by finite element (FEM) analysis software Multiphysics COMSOL. The influence of structural parameters on the performance of the sensor is discussed. The results show that the maximum sensitivity is 6000nm/RIU, when refractive index is in the range of 1.31 to 1.38. The sensor can be directly placed in the liquid and platinum layer is placed outer surface of the photonic crystal fiber, which can simplify the manufacturing process and the measurement process , has important practical value.

  7. Engineered Surfaces for Mitigation of Insect Residue Adhesion

    NASA Technical Reports Server (NTRS)

    Siochi, Emilie J.; Smith, Joseph G.; Wohl, Christopher J.; Gardner, J. M.; Penner, Ronald K.; Connell, John W.

    2013-01-01

    Maintenance of laminar flow under operational flight conditions is being investigated under NASA s Environmentally Responsible Aviation (ERA) Program. Among the challenges with natural laminar flow is the accretion of residues from insect impacts incurred during takeoff or landing. Depending on air speed, temperature, and wing structure, the critical residue height for laminar flow disruption can be as low as 4 microns near the leading edge. In this study, engineered surfaces designed to minimize insect residue adhesion were examined. The coatings studied included chemical compositions containing functional groups typically associated with abhesive (non-stick) surfaces. To reduce surface contact by liquids and enhance abhesion, the engineered surfaces consisted of these coatings doped with particulate additives to generate random surface topography, as well as coatings applied to laser ablated surfaces having precision patterned topographies. Performance evaluation of these surfaces included contact angle goniometry of pristine coatings and profilometry of surfaces after insect impacts were incurred in laboratory scale tests, wind tunnel tests and flight tests. The results illustrate the complexity of designing antifouling surfaces for effective insect contamination mitigation under dynamic conditions and suggest that superhydrophobic surfaces may not be the most effective solution for preventing insect contamination on aircraft wing leading edges.

  8. Particle engineering in pharmaceutical solids processing: surface energy considerations.

    PubMed

    Williams, Daryl R

    2015-01-01

    During the past 10 years particle engineering in the pharmaceutical industry has become a topic of increasing importance. Engineers and pharmacists need to understand and control a range of key unit manufacturing operations such as milling, granulation, crystallisation, powder mixing and dry powder inhaled drugs which can be very challenging. It has now become very clear that in many of these particle processing operations, the surface energy of the starting, intermediate or final products is a key factor in understanding the processing operation and or the final product performance. This review will consider the surface energy and surface energy heterogeneity of crystalline solids, methods for the measurement of surface energy, effects of milling on powder surface energy, adhesion and cohesion on powder mixtures, crystal habits and surface energy, surface energy and powder granulation processes, performance of DPI systems and finally crystallisation conditions and surface energy. This review will conclude that the importance of surface energy as a significant factor in understanding the performance of many particulate pharmaceutical products and processes has now been clearly established. It is still nevertheless, work in progress both in terms of development of methods and establishing the limits for when surface energy is the key variable of relevance.

  9. Adsorption ability comparison of plasma proteins on amorphous carbon surface

    NASA Astrophysics Data System (ADS)

    Takeda, Aoi; Akasaka, Hiroki; Ohshio, Shigeo; Toda, Ikumi; Nakano, Masayuki; Saitoh, Hidetoshi

    2012-11-01

    To understand why amorphous carbon (a-C:H) film shows antithrombogenicity, an adsorption ability of plasma proteins on a-C:H surface was investigated. Protein adsorption is the initial process of clot formation. The protein adsorption ability on a-C:H film surface was compared by the detection using the surface plasmon resonance (SPR) phenomenon to estimate the protein adsorption. The protein adsorption abilities of a fibrinogen (Fib) and a human γ-globulin (HGG) were estimated by the SPR method using a multilayer structure of a-C:H/Au/Cr/glass. Although the adsorption of HGG for a-C:H was saturated at 32 μM in HGG concentration, the adsorption of Fib was not saturated under the detection limit of this method. These results indicated that the adsorption ability to the a-C:H film surface of Fib was higher than HGG.

  10. Mechanism of surface modification in the plasma-surface interaction in electrical arcs

    SciTech Connect

    Timko, H.; Djurabekova, F.; Nordlund, K.; Costelle, L.; Matyash, K.; Schneider, R.; Toerklep, A.; Arnau-Izquierdo, G.; Descoeudres, A.; Calatroni, S.; Taborelli, M.; Wuensch, W.

    2010-05-01

    Electrical sparks and arcs are plasma discharges that carry large currents and can strongly modify surfaces. This damage usually comes in the form of micrometer-sized craters and frozen-in liquid on the surface. Using a combination of experiments, plasma and atomistic simulation tools, we now show that the observed formation of deep craters and liquidlike features during sparking in vacuum is explained by the impacts of energetic ions, accelerated under the given conditions in the plasma sheath to kiloelectron volt energies, on surfaces. The flux in arcs is so high that in combination with kiloelectron volt energies it produces multiple overlapping heat spikes, which can lead to cratering even in materials such as Cu, where a single heat spike normally does not.

  11. Sterilization of Surfaces with a Handheld Atmospheric Pressure Plasma

    NASA Astrophysics Data System (ADS)

    Hicks, Robert; Habib, Sara; Chan, Wai; Gonzalez, Eleazar; Tijerina, A.; Sloan, Mark

    2009-10-01

    Low temperature, atmospheric pressure plasmas have shown great promise for decontaminating the surfaces of materials and equipment. In this study, an atmospheric pressure, oxygen and argon plasma was investigated for the destruction of viruses, bacteria, and spores. The plasma was operated at an argon flow rate of 30 L/min, an oxygen flow rate of 20 mL/min, a power density of 101.0 W/cm^3 (beam area = 5.1 cm^2), and at a distance from the surface of 7.1 mm. An average 6log10 reduction of viable spores was obtained after only 45 seconds of exposure to the reactive gas. By contrast, it takes more than 35 minutes at 121^oC to sterilize anthrax in an autoclave. The plasma properties were investigated by numerical modeling and chemical titration with nitric oxide. The numerical model included a detailed reaction mechanism for the discharge as well as for the afterglow. It was predicted that at a delivered power density of 29.3 W/cm^3, 30 L/min argon, and 0.01 volume% O2, the plasma generated 1.9 x 10^14 cm-3 O atoms, 1.6 x 10^12 cm-3 ozone, 9.3 x 10^13 cm-3 O2(^1δg), and 2.9 x 10^12 cm-3 O2(^1σ^+g) at 1 cm downstream of the source. The O atom density measured by chemical titration with NO was 6.0 x 10^14 cm-3 at the same conditions. It is believe that the oxygen atoms and the O2(^1δg) metastables were responsible for killing the anthrax and other microorganisms.

  12. Surface-engineering of lentiviral vectors.

    PubMed

    Verhoeyen, Els; Cosset, François-Loïc

    2004-02-01

    Vectors derived from retroviridae offer particularly flexible properties in gene transfer applications given the numerous possible associations of various viral surface glycoproteins (determining cell tropism) with different types of retroviral cores (determining genome replication and integration). Lentiviral vectors should be preferred gene delivery vehicles over vectors derived from onco-retroviruses such as murine leukemia viruses (MLVs) that cannot transduce non-proliferating target cells. Generating lentiviral vectors pseudotyped with different viral glycoproteins (GPs) may modulate the physicochemical properties of the vectors, their interaction with the host immune system and their host range. There are however important gene transfer restrictions to some non-proliferative tissues or cell types and recent studies have shown that progenitor hematopoietic stem cells in G(0), non-activated primary blood lymphocytes or monocytes were not transducible by lentiviral vectors. Moreover, lentiviral vectors that have the capacity to deliver transgenes into specific tissues are expected to be of great value for various gene transfer applications in vivo. Several innovative approaches have been explored to overcome such problems that have given rise to novel concepts in the field and have provided promising results in preliminary evaluations in vivo. Here we review the different approaches explored to upgrade lentiviral vectors, aiming at developing vectors suitable for in vivo gene delivery.

  13. Controlled Tethering Molecules via Crystal Surface Engineering

    NASA Astrophysics Data System (ADS)

    Cheng, Stephen Z. D.; Zheng, Joseph X.; Chen, William Y.

    2004-03-01

    So far, almost all experiments in tethering chain molecules onto substrates are via "grafting to" or "grafting from" polymerizations in addition to physical absorption. Issues concerning the uniformity of the tethered chain density and the molecular weight distribution of the chains tethered by polymerization always undermine the properties experimentally observed. We proposed a novel design to precisely control the tethering density of polystyrene (PS) brushes on a poly(ethylene oxide) (PEO) or a poly(L-lactic acid) (PLLA) lamellar crystal basal surface using PEO-b-PS or PLLA-b-PS diblock copolymers. As the crystallization temperature (Tc) increased in either a PEO-b-PS/mixed solution (chrolobenzene/octane) or a PLLA-b-PS/amyl acetate solution, the PEO or PLLA lamellar thickness (d) increased, and correspondingly, the number of folds per PEO or PLLA block was reduced. The reduced tethered density (Σ*) of the PS brushes thus increased. At an onset where the PS brushes are overcrowded within the solution, a drastic slope change in the relationship between (d)-1 and Tc occurs in both cases at a Σ* between 3 - 4. This illustrates that the weak to intermediate interaction changes of the PS brushes with their neighbors may be universally represented.

  14. Cell surface engineering with edible protein nanoshells.

    PubMed

    Drachuk, Irina; Shchepelina, Olga; Harbaugh, Svetlana; Kelley-Loughnane, Nancy; Stone, Morley; Tsukruk, Vladimir V

    2013-09-23

    Natural protein (silk fibroin) nanoshells are assembled on the surface of Saccharomyces cerevisiae yeast cells without compromising their viability. The nanoshells facilitate initial protection of the cells and allow them to function in encapsulated state for some time period, afterwards being completely biodegraded and consumed by the cells. In contrast to a traditional methanol treatment, the gentle ionic treatment suggested here stabilizes the shell silk fibroin structure but does not compromise the viability of the cells, as indicated by the fast response of the encapsulated cells, with an immediate activation by the inducer molecules. Extremely high viability rates (up to 97%) and preserved activity of encapsulated cells are facilitated by cytocompatibility of the natural proteins and the formation of highly porous shells in contrast to traditional polyelectrolyte-based materials. Moreover, in a high contrast to traditional synthetic shells, the silk proteins are biodegradable and can be consumed by cells at a later stage of growth, thus releasing the cells from their temporary protective capsules. These on-demand encapsulated cells can be considered a valuable platform for biocompatible and biodegradable cell encapsulation, controlled cell protection in a synthetic environment, transfer to a device environment, and cell implantation followed by biodegradation and consumption of protective protein shells.

  15. The plasma footprint of an atmospheric pressure plasma jet on a flat polymer substrate and its relation to surface treatment

    NASA Astrophysics Data System (ADS)

    Onyshchenko, Iuliia; Nikiforov, Anton Yu.; De Geyter, Nathalie; Morent, Rino

    2016-08-01

    The aim of this work is to show the correlation between the plasma propagation in the footprint of an atmospheric pressure plasma jet on a flat polymer surface and the plasma treatment impact on the polymer properties. An argon plasma jet working in open air is used as plasma source, while PET thin films are used a substrates for plasma treatment. Light emission photographs are taken with an ICCD camera to have a close look at the generated structures in the plasma jet footprint on the surface. Water contact angle (WCA) measurement and X-ray photoelectron spectroscopy (XPS) analysis are also performed to obtain information about the impact of the plasma treatment on the PET surface characteristics. A variation in ICCD camera gate duration (1 µs, 100 µs, 50 ms) results in the photographs of the different plasma structures occurring during the plasma propagation on the flat PET surface. Contact angle measurements provide results on improvement of the PET hydrophilic character, while XPS analysis shows the distribution of atomic elements on the treated substrate surface. Light emission images help explaining the obtained WCA and XPS results. Contribution to the topical issue "6th Central European Symposium on Plasma Chemistry (CESPC-6)", edited by Nicolas Gherardi, Ester Marotta and Cristina Paradisi

  16. Manipulating superconductivity in ruthenates through Fermi surface engineering

    NASA Astrophysics Data System (ADS)

    Hsu, Yi-Ting; Cho, Weejee; Rebola, Alejandro Federico; Burganov, Bulat; Adamo, Carolina; Shen, Kyle M.; Schlom, Darrell G.; Fennie, Craig J.; Kim, Eun-Ah

    2016-07-01

    The key challenge in superconductivity research is to go beyond the historical mode of discovery-driven research. We put forth a new strategy, which is to combine theoretical developments in the weak-coupling renormalization-group approach with the experimental developments in lattice-strain-driven Fermi surface engineering. For concreteness we theoretically investigate how superconducting tendencies will be affected by strain engineering of ruthenates' Fermi surface. We first demonstrate that our approach qualitatively reproduces recent experiments under uniaxial strain. We then note that the order of a few percent strain, readily accessible to epitaxial thin films, can bring the Fermi surface close to van Hove singularity. Using the experimental observation of the change in the Fermi surface under biaxial epitaxial strain and ab initio calculations, we predict Tc for triplet pairing to be maximized by getting close to the van Hove singularities without tuning on to the singularity.

  17. Optical Diagnostics of the Plasma and Surface during Inductively Coupled Plasma Etching

    NASA Astrophysics Data System (ADS)

    Herman, Irving P.

    1999-10-01

    The use of optical diagnostics to analyze the etching of Si, Ge, and InP by chlorine in an inductively coupled plasma (ICP) is investigated. Optical probes, along with other conventional plasma diagnostics, are used to characterize the process through measurements of the constituents of the plasma and the surface composition to obtain a more complete picture of the etching process. Neutral Cl2 and Cl densities are determined by optical emission actinometry by following optical emission from Cl_2. The absolute densities of Cl_2^+ and Cl^+ are determined by laser- induced fluorescence (LIF) of Cl_2^+ and Langmuir probe measurements of the total positive ion density. The surface is probed by using laser-induced thermal desorption with an XeCl laser (308 nm) to desorb the steady-state adlayer and optical methods to detect these desorbed species. The development of a new method to detect optically these laser desorbed (LD) species is detailed, that of examining transient changes in the plasma-induced emission (PIE). This LD-PIE method is more universal than the previously reported detection by LIF (LD-LIF), but requires more calibration due to varying electron density and temperature with varying plasma conditions. This is detailed for Si etching, for which LD-PIE and LD-LIF results are compared. The calibration methods are seen to be valid when the surface is analyzed as the rf power supplied to the reactor is varied. The electron density - needed for LD-PIE calibration - is measured by microwave interferometry. An improved understanding of the etching mechanism is obtained by combining the results of each of these measurements. This work was supported by NSF Grant No. DMR-98-15846. note

  18. RF atmospheric plasma jet surface treatment of paper

    NASA Astrophysics Data System (ADS)

    Pawlat, Joanna; Terebun, Piotr; Kwiatkowski, Michał; Diatczyk, Jaroslaw

    2016-09-01

    A radio frequency RF atmospheric pressure plasma jet was used to enhance the wettability of cellulose-based paper of 90 g m-2 and 160 g m-2 grammage as a perspective platform for antibiotic sensitivity tests. Helium and argon were the carrier gases for oxygen and nitrogen; pure water and rapeseed oil were used for goniometric tests. The influence of the flow rate and gas type, the power of the discharge, and distance from the nozzle was examined. The surface structure was observed using an optical microscope. Attenuated total reflection Fourier transform infrared (ATR-FTIR) spectra were investigated in order to determine whether cellulose degradation processes occurred. The RF plasma jet allowed us to decrease the surface contact angle without drastic changes in other features of the tested material. Experiments confirmed the significant influence of the distance between the treated sample and reactor nozzle, especially for treatment times longer than 15 s due to the greater concentration of reactive species at the surface of the sample, which decreases with distance—and their accumulation effect with time. The increase of discharge power plays an important role in decreasing the surface contact angle for times longer than 10 s. Higher power had a positive effect on the amount of generated active particles and facilitated the ignition of discharge. However, a too high value can cause a rise in temperature of the material and heat-caused damage.

  19. First wall and limiter surfaces for plasma devices

    DOEpatents

    Krauss, Alan R.; Gruen, Dieter M.

    1983-01-01

    For a plasma device, a surface of a first wall or limiter with reduced loss of metal by erosion is provided by forming a monolayer of an alkali or alkaline earth metal on a substrate of a more negative metal. The surface exhibits a reduced loss of metal by erosion and particularly by sputtering and an increased secondary ion/neutral ratio resulting in a greater return of atoms escaping from the surface. In another aspect of the invention, the substrate includes a portion of the second metal and serves to replenish the surface layer with atoms of the second metal. In one process associated with self-generating desired surface, the metals as an alloy are selected to provide a first layer having a high concentration of the second metal in contrast to a very low concentration in the second layer and bulk to result in a surface with a monolayer of the second metal. When the combination of metals results in an intermetallic compound, selective removal of the first metal during an initial bombardment stage provides the surface layer with a predominance of the second metal.

  20. Transport of solar wind plasma onto the lunar nightside surface

    NASA Astrophysics Data System (ADS)

    Vorburger, A.; Wurz, P.; Barabash, S.; Futaana, Y.; Wieser, M.; Bhardwaj, A.; Dhanya, M. B.; Asamura, K.

    2016-10-01

    We present first measurements of energetic neutral atoms that originate from solar wind plasma having interacted with the lunar nightside surface. We observe two distinct energetic neutral atom (ENA) distributions parallel to the terminator, the spectral shape, and the intensity of both of which indicate that the particles originate from the bulk solar wind flow. The first distribution modifies the dayside ENA flux to reach ˜6° into the nightside and is well explained by the kinetic temperature of the solar wind protons. The second distribution, which was not predicted, reaches from the terminator to up to 30° beyond the terminator, with a maximum at ˜102° in solar zenith angle. As most likely wake transport processes for this second distribution we identify acceleration by the ambipolar electric field and by the negatively charged lunar nightside surface. In addition, our data provide the first observation indicative of a global solar zenith angle dependence of positive dayside surface potentials.

  1. Atmospheric-Pressure Plasma Cleaning of Contaminated Surfaces

    SciTech Connect

    Robert F. Hicks; Gary S. Selwyn

    2001-01-09

    Project was to develop a low-cost, environmentally benign technology for the decontamination and decommissioning of transuranic waste. With the invention of the atmospheric-pressure plasma jet the goal was achieved. This device selectively etches heavy metals from surfaces, rendering objects radiation free and suitable for decommissioning. The volatile reaction products are captured on filters, which yields a tremendous reduction in the volume of the waste. Studies on tantalum, a surrogate material for plutonium, have shown that etch rate of 6.0 microns per minute can be achieved under mild conditions. Over the past three years, we have made numerous improvements in the design of the plasma jet. It may now be operated for hundreds of hours and not undergo any degradation in performance. Furthermore, small compact units have been developed, which are easily deployed in the field.

  2. Characteristics of the surface plasma wave in a self-gravitating magnetized dusty plasma slab

    SciTech Connect

    Lee, Myoung-Jae; Jung, Young-Dae

    2015-11-15

    The dispersion properties of surface dust ion-acoustic waves in a self-gravitating magnetized dusty plasma slab are investigated. The dispersion relation is derived by using the low-frequency magnetized dusty dielectric function and the surface wave dispersion integral for the slab geometry. We find that the self-gravitating effect suppresses the frequency of surface dust ion-acoustic wave for the symmetric mode in the long wavelength regime, whereas it hardly changes the frequency for the anti-symmetric mode. As the slab thickness and the wave number increase, the surface wave frequency slowly decreases for the symmetric mode but increases significantly for the anti-symmetric mode. The influence of external magnetic field is also investigated in the case of symmetric mode. We find that the strength of the magnetic field enhances the frequency of the symmetric-mode of the surface plasma wave. The increase of magnetic field reduces the self-gravitational effect and thus the self-gravitating collapse may be suppressed and the stability of dusty objects in space is enhanced.

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

    NASA Astrophysics Data System (ADS)

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

    2012-10-01

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

  4. 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.

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

    DOE PAGES

    Tyagi, P. V.; Doleans, M.; Hannah, B.; ...

    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.

  6. Engineered surface Bloch waves in graphene-based hyperbolic metamaterials.

    PubMed

    Xiang, Yuanjiang; Guo, Jun; Dai, Xiaoyu; Wen, Shuangchun; Tang, Dingyuan

    2014-02-10

    A kind of tunable hyperbolic metamaterial (HMM) based on the graphene-dielectric layered structure at near-infrared frequencies is presented, and the engineered surface Bloch waves between graphene-based HMM and isotropic medium are investigated. Our calculations demonstrate that the frequency and frequency range of surface Bloch waves existence can be tuned by varying the Fermi energy of graphene sheets via electrostatic biasing. Moreover, we show that the frequency range of surface Bloch waves existence can be broadened by decreasing the thickness of the dielectric in the graphene-dielectric layered structure or by increasing the layer number of graphene sheets.

  7. Cell surface engineering of microorganisms towards adsorption of heavy metals.

    PubMed

    Li, Peng-Song; Tao, Hu-Chun

    2015-06-01

    Heavy metal contamination has become a worldwide environmental concern due to its toxicity, non-degradability and food-chain bioaccumulation. Conventional physical and chemical treatment methods for heavy metal removal have disadvantages such as cost-intensiveness, incomplete removal, secondary pollution and the lack of metal specificity. Microbial biomass-based biosorption is one of the approaches gaining increasing attention because it is effective, cheap, and environmental friendly and can work well at low concentrations. To enhance the adsorption properties of microbial cells to heavy metal ions, the cell surface display of various metal-binding proteins/peptides have been performed using a cell surface engineering approach. The surface engineering of Gram-negative bacteria, Gram-positive bacteria and yeast towards the adsorption of heavy metals are reviewed in this article. The problems and future perspectives of this technology are discussed.

  8. Ion Dynamics and ICRH Heating in the Exhaust Plasma of The VASIMR Engine

    NASA Astrophysics Data System (ADS)

    Bering, E. A., III; Chang-Díaz, F. R.; Squire, J. P.; Jacobson, V.; Ilin, A.; Winter, D. S.; Bengtson, R. D.; Gibson, J. N.; Glober, T. W.; Brukardt, M.; Rodriguez, W.

    2002-01-01

    The Variable Specific Impulse Magnetoplasma Rocket (VASIMR) is a high power, radio frequency-driven magnetoplasma rocket, capable of Isp/thrust modulation at constant power. The plasma is produced by an integrated helicon discharge. However, the bulk of the plasma energy is added in a separate downstream stage by ion cyclotron resonance heating (ICRH.) Axial momentum is obtained by the adiabatic expansion of the plasma in a magnetic nozzle. Exhaust variation in the VASIMR is primarily achieved by the selective partitioning of the RF power to the helicon and ICRH systems, with the proper adjustment of the propellant flow. A laboratory simulation of the 25 kW proof of concept VASIMIR engine has been under development and test at NASA-JSC for several years. Experimentally, high density, stable plasma discharges have been generated in Helium, Hydrogen, Deuterium, Argon and Xenon. This paper will review the plasma diagnostic results obtained in 2000-2002 in a continuing series of performance optimization and design development studies. Available plasma diagnostics include a triple probe, a Mach probe, a bolometer, a television monitor, an H- photometer, a spectrometer, neutral gas pressure and flow measurements, several gridded energy analyzers (retarding potential analyzer or RPA), a surface recombination probe system, an emission probe, a directional, steerable RPA and other diagnostics. Reciprocating Langmuir and Mach probes are the primary plasma diagnostics. The Langmuir probe measures electron density and temperature profiles while the Mach probe measures flow profiles. Together this gives total plasma particle flux. An array of thermocouples provides a temperature map of the system. Ion flow velocities are estimated through three techniques: Mach probes, retarding potential analyzer, and spectroscopic measurements. During 2000-2002, we have performed a series of experiments on the VASIMR apparatus with several objectives, to explore the parameter space that

  9. Active screen plasma nitriding enhances cell attachment to polymer surfaces

    NASA Astrophysics Data System (ADS)

    Kaklamani, Georgia; Bowen, James; Mehrban, Nazia; Dong, Hanshan; Grover, Liam M.; Stamboulis, Artemis

    2013-05-01

    Active screen plasma nitriding (ASPN) is a well-established technique used for the surface modification of materials, the result of which is often a product with enhanced functional performance. Here we report the modification of the chemical and mechanical properties of ultra-high molecular weight poly(ethylene) (UHMWPE) using 80:20 (v/v) N2/H2 ASPN, followed by growth of 3T3 fibroblasts on the treated and untreated polymer surfaces. ASPN-treated UHMWPE showed extensive fibroblast attachment within 3 h of seeding, whereas fibroblasts did not successfully attach to untreated UHMWPE. Fibroblast-coated surfaces were maintained for up to 28 days, monitoring their metabolic activity and morphology throughout. The chemical properties of the ASPN-treated UHMWPE surface were studied using X-ray photoelectron spectroscopy, revealing the presence of Csbnd N, Cdbnd N, and Ctbnd N chemical bonds. The elastic modulus, surface topography, and adhesion properties of the ASPN-treated UHMWPE surface were studied over 28 days during sample storage under ambient conditions and during immersion in two commonly used cell culture media.

  10. Blistering on tungsten surface exposed to high flux deuterium plasma

    NASA Astrophysics Data System (ADS)

    Xu, H. Y.; Liu, W.; Luo, G. N.; Yuan, Y.; Jia, Y. Z.; Fu, B. Q.; De Temmerman, G.

    2016-04-01

    The blistering behaviour of tungsten surfaces exposed to very high fluxes (1-2 × 1024/m2/s) of low energy (38 eV) deuterium plasmas was investigated as a function of ion fluence (0.2-7 × 1026 D/m2) and surface temperature (423-873 K). Blisters were observed under all conditions, especially up to temperatures of 873 K. The blister parameters are evaluated with blister size, blister density and surface coverage. The blister size always peaked at less than 0.5 μm and no blister larger than 10 μm is observed even at high fluence. The blister densities are found in high magnitude of 106 blisters/m2, with the surface coverages lower than 2%. The formation of cracks in the sub-surface region was observed by cross-section imaging. Changes in blister size and shape with fluence and temperature suggest processes of predominantly nucleation and subsequent growth of blisters. The smaller blister size is considered to be caused by a combination of flux-related effects such as enhanced defect formation in the near surface region, reduced deuterium diffusivity and relatively short exposure times.

  11. Lunar Surface Access Module Pump-Fed Engine Turbopump Technology

    NASA Technical Reports Server (NTRS)

    Thornton, Randall J.

    2007-01-01

    The need for a high specific impulse LOX/LH2 pump-fed lunar lander engine has been established by NASA for the new Exploration architecture. Preliminary studies indicate that a 4 engine cluster in the thrust range of 9,000-lbf each is a likely configuration for the main propulsion of the manned lunar lander vehicle. The main Lunar Surface Access Module engines will likely be responsible for mid-course correction burns, lunar orbit insertion burns, a deorbit burn, and the powered descent to the lunar surface. This multi-task engine philosophy imposes a wide throttling requirement on the engines in the range of 10:1. Marshall Space Flight Center has initiated an internal effort to mature the technologies needed for full scale development of such a LOX/LH2 pump-fed engine. In particular, a fuel turbopump is being designed and fabricated at MSFC to address the issues that a small high speed turbopump of this class will face. These issues include adequate throttling performance of the pump and turbine over a very wide operating range. The small scale of the hardware presents issues including performance scaling, and manufacturing issues like that will challenge the traditional methods we have used to fabricate and assemble larger scale turbopumps. The small high speed turbopump being developed at MSFC will operate at speeds greater than 100,000-rpm. These speeds create issues that include structural dynamics and high cycle fatigue as well as rotordynamic stability. The fuel turbopump development at MSFC will address these issues, and plans are in work for component level testing as well as operation in a test bed engine environment. The fuel turbopump design is nearing completion and described herein.

  12. Engineering nanoscale surface features to sustain microparticle rolling in flow.

    PubMed

    Kalasin, Surachate; Santore, Maria M

    2015-05-26

    Nanoscopic features of channel walls are often engineered to facilitate microfluidic transport, for instance when surface charge enables electro-osmosis or when grooves drive mixing. The dynamic or rolling adhesion of flowing microparticles on a channel wall holds potential to accomplish particle sorting or to selectively transfer reactive species or signals between the wall and flowing particles. Inspired by cell rolling under the direction of adhesion molecules called selectins, we present an engineered platform in which the rolling of flowing microparticles is sustained through the incorporation of entirely synthetic, discrete, nanoscale, attractive features into the nonadhesive (electrostatically repulsive) surface of a flow channel. Focusing on one example or type of nanoscale feature and probing the impact of broad systematic variations in surface feature loading and processing parameters, this study demonstrates how relatively flat, weakly adhesive nanoscale features, positioned with average spacings on the order of tens of nanometers, can produce sustained microparticle rolling. We further demonstrate how the rolling velocity and travel distance depend on flow and surface design. We identify classes of related surfaces that fail to support rolling and present a state space that identifies combinations of surface and processing variables corresponding to transitions between rolling, free particle motion, and arrest. Finally we identify combinations of parameters (surface length scales, particle size, flow rates) where particles can be manipulated with size-selectivity.

  13. Lunar Surface Access Module Descent Engine Turbopump Technology: Detailed Design

    NASA Technical Reports Server (NTRS)

    Alarez, Erika; Thornton, Randall J.; Forbes, John C.

    2008-01-01

    The need for a high specific impulse LOX/LH2 pump-fed lunar lander engine has been established by NASA for the new lunar exploration architecture. Studies indicate that a 4-engine cluster in the thrust range of 9,000-lbf each is a candidate configuration for the main propulsion of the manned lunar lander vehicle. The lander descent engine will be required to perform minor mid-course corrections, a Lunar Orbit Insertion (LOI) burn, a de-orbit burn, and the powered descent onto the lunar surface. In order to achieve the wide range of thrust required, the engines must be capable of throttling approximately 10:1. Working under internal research and development funding, NASA Marshall Space Flight Center (MSFC) has been conducting the development of a 9,000-lbf LOX/LH2 lunar lander descent engine testbed. This paper highlights the detailed design and analysis efforts to develop the lander engine Fuel Turbopump (FTP) whose operating speeds range from 30,000-rpm to 100,000-rpm. The capability of the FTP to operate across this wide range of speeds imposes several structural and dynamic challenges, and the small size of the FTP creates scaling and manufacturing challenges that are also addressed in this paper.

  14. Lunar Surface Access Module Descent Engine Turbopump Technology: Detailed Design

    NASA Technical Reports Server (NTRS)

    Alvarez, Erika; Forbes, John C.; Thornton, Randall J.

    2010-01-01

    The need for a high specific impulse LOX/LH2 pump-fed lunar lander engine has been established by NASA for the new lunar exploration architecture. Studies indicate that a 4-engine cluster in the thrust range of 9,000-lbf each is a candidate configuration for the main propulsion of the manned lunar lander vehicle. The lander descent engine will be required to perform multiple burns including the powered descent onto the lunar surface. In order to achieve the wide range of thrust required, the engines must be capable of throttling approximately 10:1. Working under internal research and development funding, NASA Marshall Space Flight Center (MSFC) has been conducting the development of a 9,000-lbf LOX/LH2 lunar lander descent engine technology testbed. This paper highlights the detailed design and analysis efforts to develop the lander engine Fuel Turbopump (FTP) whose operating speeds range from 30,000-rpm to 100,000-rpm. The capability of the FTP to operate across this wide range of speeds imposes several structural and dynamic challenges, and the small size of the FTP creates scaling and manufacturing challenges that are also addressed in this paper.

  15. Molecular engineering and characterization of self-assembled biorecognition surfaces

    NASA Astrophysics Data System (ADS)

    Pan, Sheng

    The development of molecular engineering techniques for the fabrication of biomaterial surfaces is of importance in the field of biomaterials. It offers opportunities for better understanding of biological processes on material surfaces and rational design of contemporary biomaterials. Our work in this area aims to develop novel engineering strategies to design biorecognition surfaces via self-assembly and surface derivatization. Fundamental issues regarding self-assembled monolayer (SAM) structure, formation kinetics, and chemical derivatization were investigated systematically using electron spectroscopy for chemical analysis (ESCA), time-of-flight secondary ion mass spectrometry (TOF-SIMS), infrared reflection absorption spectroscopy (IRAS), atomic force microscopy (AFM), and contact angle measurements. Novel engineering concepts based on multifunctionality and statistical pattern matching were introduced and applied to develop biomimetic surfaces. Our study illustrated that molecules underwent structural transition and orientation development during self-assembly formation, from a disordered, low-density, more liquid-like structure to a highly ordered, closed-packed crystalline-like structure. Surface properties, such as wettability and the reactivity of outermost functional groups can be related to film structure, packing density, as well as molecular orientation. Given the order and organization of SAMs, the accessibility and reactivity of the outermost functional groups, reaction kinetics, stoichiometry, and SAMs stability were studied systematically by surface derivatization of trifluoroacetic anhydride (TFAA). The TFAA derivatization reactions exhibited rapid kinetics on the hydroxyl-terminated SAMs. The data from complementary surface analytical techniques consistently indicated a nearly complete surface reaction. Biomimetic surfaces were made by random immobilization of amino acid of arginine (R), glycine (G), and aspartic acid (D) on well-defined SAMs

  16. Review: engineering particles using the aerosol-through-plasma method

    SciTech Connect

    Phillips, Jonathan; Luhrs, Claudia C; Richard, Monique

    2009-01-01

    For decades, plasma processing of materials on the nanoscale has been an underlying enabling technology for many 'planar' technologies, particularly virtually every aspect of modern electronics from integrated-circuit fabrication with nanoscale elements to the newest generation of photovoltaics. However, it is only recent developments that suggest that plasma processing can be used to make 'particulate' structures of value in fields, including catalysis, drug delivery, imaging, higher energy density batteries, and other forms of energy storage. In this paper, the development of the science and technology of one class of plasma production of particulates, namely, aerosol-through-plasma (A-T-P), is reviewed. Various plasma systems, particularly RF and microwave, have been used to create nanoparticles of metals and ceramics, as well as supported metal catalysts. Gradually, the complexity of the nanoparticles, and concomitantly their potential value, has increased. First, unique two-layer particles were generated. These were postprocessed to create unique three-layer nanoscale particles. Also, the technique has been successfully employed to make other high-value materials, including carbon nanotubes, unsupported graphene, and spherical boron nitride. Some interesting plasma science has also emerged from efforts to characterize and map aerosol-containing plasmas. For example, it is clear that even a very low concentration of particles dramatically changes plasma characteristics. Some have also argued that the local-thermodynamic-equilibrium approach is inappropriate to these systems. Instead, it has been suggested that charged- and neutral-species models must be independently developed and allowed to 'interact' only in generation terms.

  17. Enhanced biocompatibility of TiO2 surfaces by highly reactive plasma

    NASA Astrophysics Data System (ADS)

    Junkar, Ita; Kulkarni, Mukta; Drašler, Barbara; Rugelj, Neža; Recek, Nina; Drobne, Damjana; Kovač, Janez; Humpolicek, Petr; Iglič, Aleš; Mozetič, Miran

    2016-06-01

    In the present study the biological response to various nanotopographic features after gaseous plasma treatment were studied. The usefulness of nanostructured surfaces for implantable materials has already been acknowledged, while less is known on the combined effect of nanostructured plasma modified surfaces. In the present work the influence of oxygen plasma treatment on nanostructured titanium oxide (TiO2) surfaces was studied. Characterization of the TiO2 surface chemical composition and morphological features was analyzed after plasma modification by x-ray photoelectron spectroscopy and by scanning electron microscopy while surface wettability was studied with measuring the water contact angle. Cell adhesion and morphology was assessed from images taken with scanning electron microscopy, whereas cell viability was measured with a calorimetric assay. The obtained results showed that oxygen plasma treatment of TiO2 nanotube surfaces significantly influences the adhesion and morphology of osteoblast-like cells in comparison to untreated nanostructured surfaces. Marked changes in surface composition of plasma treated surfaces were observed, as plasma treatment removed hydrocarbon contamination and removed fluorine impurities, which were present due to the electrochemical anodization process. However no differences in wettability of untreated and plasma treated surfaces were noticed. Treatment with oxygen plasma stimulated osteoblast-like cell adhesion and spreading on the nanostructured surface, suggesting the possible use of oxygen plasma surface treatment to enhance osteoblast-like cell response.

  18. Recent advances in engineering topography mediated antibacterial surfaces

    NASA Astrophysics Data System (ADS)

    Hasan, Jafar; Chatterjee, Kaushik

    2015-09-01

    The tendency of bacterial cells to adhere and colonize a material surface leading to biofilm formation is a fundamental challenge underlying many different applications including microbial infections associated with biomedical devices and products. Although, bacterial attachment to surfaces has been extensively studied in the past, the effect of surface topography on bacteria-material interactions has received little attention until more recently. We review the recent progress in surface topography based approaches for engineering antibacterial surfaces. Biomimicry of antibacterial surfaces in nature is a popular strategy. Whereas earlier endeavors in the field aimed at minimizing cell attachment, more recent efforts have focused on developing bactericidal surfaces. However, not all such topography mediated bactericidal surfaces are necessarily cytocompatible thus underscoring the need for continued efforts for research in this area for developing antibacterial and yet cytocompatible surfaces for use in implantable biomedical applications. This mini-review provides a brief overview of the current strategies and challenges in the emerging field of topography mediated antibacterial surfaces.

  19. Recent advances in engineering topography mediated antibacterial surfaces

    PubMed Central

    Hasan, Jafar

    2015-01-01

    The tendency of bacterial cells to adhere and colonize a material surface leading to biofilm formation is a fundamental challenge underlying many different applications including microbial infections associated with biomedical devices and products. Although, bacterial attachment to surfaces has been extensively studied in the past, the effect of surface topography on bacteria–material interactions has received little attention until more recently. We review the recent progress in surface topography based approaches for engineering antibacterial surfaces. Biomimicry of antibacterial surfaces in nature is a popular strategy. Whereas earlier endeavors in the field aimed at minimizing cell attachment, more recent efforts have focused on developing bactericidal surfaces. However, not all such topography mediated bactericidal surfaces are necessarily cytocompatible thus underscoring the need for continued efforts for research in this area for developing antibacterial and yet cytocompatible surfaces for use in implantable biomedical applications. This mini-review provides a brief overview of the current strategies and challenges in the emerging field of topography mediated antibacterial surfaces. PMID:26372264

  20. Plasma treatments of wool fiber surface for microfluidic applications

    SciTech Connect

    Jeon, So-Hyoun; Hwang, Ki-Hwan; Lee, Jin Su; Boo, Jin-Hyo; Yun, Sang H.

    2015-09-15

    Highlights: • We used atmospheric plasma for tuning the wettability of wool fibers. • The wicking rates of the wool fibers increased with increasing treatment time. • The increasing of wettability results in removement of fatty acid on the wool surface. - Abstract: Recent progress in health diagnostics has led to the development of simple and inexpensive systems. Thread-based microfluidic devices allow for portable and inexpensive field-based technologies enabling medical diagnostics, environmental monitoring, and food safety analysis. However, controlling the flow rate of wool thread, which is a very important part of thread-based microfluidic devices, is quite difficult. For this reason, we focused on thread-based microfluidics in the study. We developed a method of changing the wettability of hydrophobic thread, including wool thread. Thus, using natural wool thread as a channel, we demonstrate herein that the manipulation of the liquid flow, such as micro selecting and micro mixing, can be achieved by applying plasma treatment to wool thread. In addition to enabling the flow control of the treated wool channels consisting of all natural substances, this procedure will also be beneficial for biological sensing devices. We found that wools treated with various gases have different flow rates. We used an atmospheric plasma with O{sub 2}, N{sub 2} and Ar gases.

  1. [Elimination of haloperidol from erythrocytes surfaces supernatant and blood plasma].

    PubMed

    Shanidze, L A

    2005-01-01

    The aim of the study was to investigate the adsorption rate of haloperidol on erythrocytes surfaces. The pharmacokinetic and pharmacodynamic parameters of haloperidol were monitored in the experiment. The neuroleptic was administered to 12 adult dogs and the blood samples were collected for further analysis following 20, 30, 60, 180, 240, 360, 420 and 480 minutes after the injection. The groups of samples (blood plasma and supernatant) were monitored during this period. The differences between haloperidol concentration in the supernatant and blood plasma were compared. Our data have shown that dynamics of the elimination of intact and acidified forms of haloperidol from the supernatant and the blood serum are not the same. Intact and acidified forms are differently regulated by plasma. albumines and globulines. The process of redistribution of haloperidol between the both substrates takes place, while the supernatant has a donor function for the free form of haloperidol and represents the acceptor of the haloperidol's metabolites. This provides the possibility to develop multidiscipline approach to the optimization to the prescription of haloperidol.

  2. RF plasma based selective modification of hydrophilic regions on super hydrophobic surface

    NASA Astrophysics Data System (ADS)

    Lee, Jaehyun; Hwang, Sangyeon; Cho, Dae-Hyun; Hong, Jungwoo; Shin, Jennifer H.; Byun, Doyoung

    2017-02-01

    Selective modification and regional alterations of the surface property have gained a great deal of attention to many engineers. In this paper, we present a simple, a cost-effective, and amendable reforming method for disparate patterns of hydrophilic regions on super-hydrophobic surfaces. Uniform super-hydrophobic layer (Contact angle; CA > 150°, root mean square (RMS) roughness ∼0.28 nm) can be formed using the atmospheric radio frequency (RF) plasma on top of the selective hydrophilic (CA ∼ 70°, RMS roughness ∼0.34 nm) patterns imprinted by electrohydrodynamic (EHD) jet printing technology with polar alcohols (butyl carbitol or ethanol). The wettability of the modified surface was investigated qualitatively utilizing scanning electron microscopy (SEM), atomic force microscopy (AFM), and wavelength scanning interferometer (WSI). Secondary ion mass spectroscopy (SIMS) analysis showed that the alcohol addiction reaction changed the types of radicals on the super-hydrophobic surface. The wettability was found to depend sensitively on chemical radicals on the surface, not on surface morphology (particle size and surface roughness). Furthermore, three different kinds of representative hydrophilic samples (polystyrene nano-particle aqueous solution, Salmonella bacteria medium, and poly(3,4-ethylenediocythiophene) ink) were tested for uniform deposition onto the desired hydrophilic regions. This simple strategy would have broad applications in various research fields that require selective deposition of target materials.

  3. Surface conductivity dependent dynamic behaviour of an ultrafine atmospheric pressure plasma jet for microscale surface processing

    NASA Astrophysics Data System (ADS)

    Abuzairi, Tomy; Okada, Mitsuru; Bhattacharjee, Sudeep; Nagatsu, Masaaki

    2016-12-01

    An experimental study on the dynamic behaviour of microcapillary atmospheric pressure plasma jets (APPJs) with 5 μm tip size for surfaces of different conductivity is reported. Electrical and spatio-temporal characteristics of the APPJs are monitored using high voltage probe, current monitor and high speed intensified charge couple device camera. From these experimental results, we presented a simple model to understand the electrical discharge characteristics of the capillary APPJs with double electrodes, and estimated the velocity of the ionization fronts in the jet and the electron density to be 3.5-4.2 km/s and 2-7 × 1017 m-3. By analyzing the dynamics of the microcapillary APPJs for different substrate materials, it was found that the surface irradiation area strongly depended on the substrate conductivity and permittivity, especially in the case of polymer-like substrate, surface irradiation area was significantly broadened probably due to the repelling behaviour of the plasma jets from the accumulated electrical charges on the polymer surface. The effect of applying a substrate bias in the range from -900 V to +900 V on the plasma irradiation onto the substrates was also investigated. From the knowledge of the present results, it is helpful for choosing the substrate materials for microscale surface modification.

  4. Ion extraction from a saddle antenna RF surface plasma source

    SciTech Connect

    Dudnikov, V. Johnson, R. P.; Han, B.; Murray, S.; Pennisi, T.; Piller, C.; Santana, M.; Stockli, M.; Welton, R.; Breitschopf, J.; Dudnikova, G.

    2015-04-08

    Existing RF Surface Plasma Sources (SPS) for accelerators have specific efficiencies for H{sup +} and H{sup −} ion generation around 3 to 5 mA/cm{sup 2} per kW, where about 50 kW of RF power is typically needed for 50 mA beam current production. The Saddle Antenna (SA) SPS described here was developed to improve H{sup −} ion production efficiency and SPS reliability and availability. At low RF power, the efficiency of positive ion generation in the plasma has been improved to 200 mA/cm{sup 2} per kW of RF power at 13.56 MHz. Initial cesiation of the SPS was performed by heating cesium chromate cartridges by discharge as was done in the very first versions of the SPS. A small oven to decompose cesium compounds and alloys was developed and tested. After cesiation, the current of negative ions to the collector was increased from 1 mA to 10 mA with RF power ∼1.5 kW in the plasma (6 mm diameter emission aperture) and up to 30 mA with ∼4 kW RF power in the plasma and 250 Gauss longitudinal magnetic field. The ratio of electron current to negative ion current was improved from 30 to 2. Stable generation of H{sup −} beam without intensity degradation was demonstrated in the AlN discharge chamber for a long time at high discharge power in an RF SPS with an external antenna. Continuous wave (CW) operation of the SA SPS has been tested on the small test stand. The general design of the CW SA SPS is based on the pulsed version. Some modifications were made to improve the cooling and cesiation stability. The extracted collector current can be increased significantly by optimizing the longitudinal magnetic field in the discharge chamber. CW operation with negative ion extraction was tested with RF power up to 1.8 kW from the generator (∼1.2 kW in the plasma) with production up to Ic=7 mA. Long term operation was tested with 1.2 kW from the RF generator (∼0.8 kW in the plasma) with production of Ic=5 mA, Iex ∼15 mA (Uex=8 kV, Uc=14 kV)

  5. Tailorable reflection of surface plasmons in defect engineered graphene

    NASA Astrophysics Data System (ADS)

    Luo, Weiwei; Cai, Wei; Wu, Wei; Xiang, Yinxiao; Ren, Mengxin; Zhang, Xinzheng; Xu, Jingjun

    2016-12-01

    The electrical, optical, mechanical and thermal properties of graphene can be significantly altered by defects, thus engineering the defects in graphene is promising for applications in functionalized materials and nanoscale devices. Here the propagations of surface plasmon waves near graphene defect boundaries created by ion beams are studied. Specifically, plasmon reflections are observed near the induced defect boundaries for the first time, which implies that ion-irradiation induced defects act as efficient scattering centers for the plasmonic waves, just like the native grain boundaries. Moreover, engineering the defects with varied ion doses results in tailorable plasmon reflection properties due to changed defect degrees. The controllable plasmon reflections near ion induced defect boundaries open up a new avenue for plasmon wave engineering.

  6. Plasma-induced conversion of surface-adsorbed hydrocarbons

    SciTech Connect

    Sackinger, W.M.

    1992-01-01

    Experimental results are reported for an electrical device for direct conversion of methane into higher hydrocarbons. A microchannel plate is excited with electrons from a photoemissive source, and electron impact ionization of methane on the inner surfaces of the microchannels creates an ion feedback process. The resulting low-density plasma creates higher hydrocarbons when charged particles impact the surfaces at grazing incidence. The production Of C{sub 2} to C{sub 8}-containing gases was noted, with a selectivity for C{sub 2} of 39% in one case. The proportions of converted products and the conversion rates depend upon the electrical voltage, the microchannel geometry, and the operating pressure. Conversion rates increase with operating pressure.

  7. Plasma-induced conversion of surface-adsorbed hydrocarbons

    SciTech Connect

    Sackinger, W.M.

    1992-07-01

    Experimental results are reported for an electrical device for direct conversion of methane into higher hydrocarbons. A microchannel plate is excited with electrons from a photoemissive source, and electron impact ionization of methane on the inner surfaces of the microchannels creates an ion feedback process. The resulting low-density plasma creates higher hydrocarbons when charged particles impact the surfaces at grazing incidence. The production Of C{sub 2} to C{sub 8}-containing gases was noted, with a selectivity for C{sub 2} of 39% in one case. The proportions of converted products and the conversion rates depend upon the electrical voltage, the microchannel geometry, and the operating pressure. Conversion rates increase with operating pressure.

  8. Focal Adhesion of Osteoblastic Cells on Titanium Surface with Amine Functionalities Formed by Plasma Polymerization

    NASA Astrophysics Data System (ADS)

    Song, Heesang; Jung, Sang Chul; Kim, Byung Hoon

    2012-08-01

    To enhance the focal adhesion of osteoblastic cells on a titanium surface, plasma polymerized allyl amine (AAm) thin films were deposited by plasma polymerization. This plasma polymer functionalization of titanium is advantageous for osteoblastic focal adhesion formation. Such Ti surfaces are useful for the fabrication of titanium-based dental implants for enhancement of osseointegration.

  9. Shukla-Spatschek diffusion effects on surface plasma waves in astrophysical turbulent plasmas

    NASA Astrophysics Data System (ADS)

    Lee, Myoung-Jae; Jung, Young-Dae

    2017-02-01

    The effects of Shukla-Spatschek turbulent diffusion on a temporal mode of surface waves propagating at the interface of an astrophysical turbulent plasma are investigated. The damping rates for high and low modes of surface wave are kinetically derived by employing the Vlasov-Poisson equation and the specular reflection boundary condition. We found that the diffusion caused by the fluctuating electric fields leads to damping for both high and low modes of surface waves. The high-mode damping is enhanced with an increase of the wavenumber and the diffusion coefficient, but suppressed by an increase of electron thermal energy. By contrast, the low-mode damping is suppressed as the wavenumber and the thermal energy increase although it is enhanced as the diffusion increases. The variation of the damping rate due to the Shukla-Spatschek turbulent diffusion is also discussed.

  10. Apparatus for coating a surface with a metal utilizing a plasma source

    DOEpatents

    Brown, Ian G.; MacGill, Robert A.; Galvin, James E.

    1991-01-01

    An apparatus and method for coating or layering a surface with a metal utilizing a metal vapor vacuum arc plasma source. The apparatus includes a trigger mechanism for actuating the metal vacuum vapor arc plasma source in a pulsed mode at a predetermined rate. The surface or substrate to be coated or layered is supported in position with the plasma source in a vacuum chamber. The surface is electrically biased for a selected period of time during the pulsed mode of operation of the plasma source. Both the pulsing of the metal vapor vacuum arc plasma source and the electrical biasing of the surface are synchronized for selected periods of time.

  11. Retention of Sputtered Molybdenum on Ion Engine Discharge Chamber Surfaces

    NASA Technical Reports Server (NTRS)

    Sovey, James S.; Dever, Joyce A.; Power, John L.

    2001-01-01

    Grit-blasted anode surfaces are commonly used in ion engines to ensure adherence of sputtered coatings. Next generation ion engines will require higher power levels, longer operating times, and thus there will likely be thicker sputtered coatings on their anode surfaces than observed to date on 2.3 kW-class xenon ion engines. The thickness of coatings on the anode of a 10 kW, 40-centimeter diameter thruster, for example, may be 22 micrometers or more after extended operation. Grit-blasted wire mesh, titanium, and aluminum coupons were coated with molybdenum at accelerated rates to establish coating stability after the deposition process and after thermal cycling tests. These accelerated deposition rates are roughly three orders of magnitude more rapid than the rates at which the screen grid is sputtered in a 2.3 kW-class, 30-centimeter diameter ion engine. Using both RF and DC sputtering processes, the molybdenum coating thicknesses ranged from 8 to 130 micrometers, and deposition rates from 1.8 micrometers per hour to 5.1 micrometers per hour. In all cases, the molybdenum coatings were stable after the deposition process, and there was no evidence of spalling of the coatings after 20 cycles from about -60 to +320 C. The stable, 130 micrometer molybdenum coating on wire mesh is 26 times thicker than the thickest coating found on the anode of a 2.3 kW, xenon ion engine that was tested for 8200 hr. Additionally, this coating on wire mesh coupon is estimated to be a factor of greater than 4 thicker than one would expect to obtain on the anode of the next generation ion engine which may have xenon throughputs as high as 550 kg.

  12. Insoluble Coatings for Stirling Engine Heat Pipe Condenser Surfaces

    NASA Technical Reports Server (NTRS)

    Dussinger, Peter M.; Lindemuth, James E.

    1997-01-01

    The principal objective of this Phase 2 SBIR program was to develop and demonstrate a practically insoluble coating for nickel-based superalloys for Stirling engine heat pipe applications. Specific technical objectives of the program were: (1) Determine the solubility corrosion rates for Nickel 200, Inconel 718, and Udimet 72OLI in a simulated Stirling engine heat pipe environment, (2) Develop coating processes and techniques for capillary groove and screen wick structures, (3) Evaluate the durability and solubility corrosion rates for capillary groove and screen wick structures coated with an insoluble coating in cylindrical heat pipes operating under Stirling engine conditions, and (4) Design and fabricate a coated full-scale, partial segment of the current Stirling engine heat pipe for the Stirling Space Power Convertor program. The work effort successfully demonstrated a two-step nickel aluminide coating process for groove wick structures and interior wall surfaces in contact with liquid metals; demonstrated a one-step nickel aluminide coating process for nickel screen wick structures; and developed and demonstrated a two-step aluminum-to-nickel aluminide coating process for nickel screen wick structures. In addition, the full-scale, partial segment was fabricated and the interior surfaces and wick structures were coated. The heat pipe was charged with sodium, processed, and scheduled to be life tested for up to ten years as a Phase 3 effort.

  13. Engineered microtopographies and surface chemistries direct cell attachment and function

    NASA Astrophysics Data System (ADS)

    Magin, Chelsea Marie

    Harrison, in 1914, first recognized that cells respond to physicochemical cues such as substratum topography when he observed that fibroblasts elongated while cultured on spider silk. Recently, techniques developed in the micro-electronics industry have been used to create molds for producing microscaled topographies with various shapes and spatial arrangements. Although these patterning techniques are well-established, very little is known about the mechanisms underlying cell sensing and response to microtopographies. In this work cellular micro-environments with varying surface topographies and chemistries were evaluated with marine organisms and mammalian cells to investigate cellular sensing and response. Biofouling---the accumulation of micro-organisms, plants, and animals on submerged surfaces---is an environmental and economic concern. Engineered topographies, replicated in polydimethylsiloxane elastomer (PDMSe) and functionalized poly(ethylene glycol)-dimethacrylate (PEGDMA) hydrogels, were evaluated for inhibition of marine fouling organism attachment. Microtopographies replicated in PDMSe inhibited attachment of the marine bacterium, Cobetia marina up to 99% versus smooth. The average normalized attachment densities of cells of C. marina and zoospores of the green algae Ulva on PDMSe topographies scaled inversely with the Engineered Roughness Index (ERIII), a representation of surface energy. Attachment densities of Ulva from four assays and C. marina from two growth phases to PDMSe surfaces scaled inversely with one equation: ERI II multiplied by the Reynolds number of the organism (Re) (R 2 = 0.77). The same microtopographies created in PDMSe reduced the initial attachment density and attachment strength of cells of the diatoms Navicula incerta and Seminavis robusta compared to smooth PDMSe. The average normalized attachment density of Navicula after exposure to shear stress (48 Pa) was correlated with the contact area between the diatom and a

  14. Advanced Vacuum Plasma Spray (VPS) for a Robust, Longlife and Safe Space Shuttle Main Engine (SSME)

    NASA Technical Reports Server (NTRS)

    Holmes, Richard R.; Elam, Sandra K.; McKechnie, Timothy N.; Power, Christopher A.

    2010-01-01

    In 1984, the Vacuum Plasma Spray Lab was built at NASA/Marshall Space Flight Center for applying durable, protective coatings to turbine blades for the space shuttle main engine (SSME) high pressure fuel turbopump. Existing turbine blades were cracking and breaking off after five hot fire tests while VPS coated turbine blades showed no wear or cracking after 40 hot fire tests. Following that, a major manufacturing problem of copper coatings peeling off the SSME Titanium Main Fuel Valve Housing was corrected with a tenacious VPS copper coating. A patented VPS process utilizing Functional Gradient Material (FGM) application was developed to build ceramic lined metallic cartridges for space furnace experiments, safely containing gallium arsenide at 1260 degrees centigrade. The VPS/FGM process was then translated to build robust, long life, liquid rocket combustion chambers for the space shuttle main engine. A 5K (5,000 Lb. thrust) thruster with the VPS/FGM protective coating experienced 220 hot firing tests in pristine condition with no wear compared to the SSME which showed blanching (surface pulverization) and cooling channel cracks in less than 30 of the same hot firing tests. After 35 of the hot firing tests, the injector face plates disintegrated. The VPS/FGM process was then applied to spraying protective thermal barrier coatings on the face plates which showed 50% cooler operating temperature, with no wear after 50 hot fire tests. Cooling channels were closed out in two weeks, compared to one year for the SSME. Working up the TRL (Technology Readiness Level) to establish the VPS/FGM process as viable technology, a 40K thruster was built and is currently being tested. Proposed is to build a J-2X size liquid rocket engine as the final step in establishing the VPS/FGM process TRL for space flight.

  15. Liquid Lithium Limiter Effects on Tokamak Plasmas and Plasma-Liquid Surface Interactions

    SciTech Connect

    R. Kaita; R. Majeski; R. Doerner; G. Antar; M. Baldwin; R. Conn; P. Efthimion; M. Finkenthal; D. Hoffman; B. Jones; S. Krashenninikov; H. Kugel; S. Luckhardt; R. Maingi; J. Menard; T. Munsat; D. Stutman; G. Taylor; J. Timberlake; V. Soukhanovskii; D. Whyte; R. Woolley; L. Zakharov

    2002-10-15

    We present results from the first experiments with a large area liquid lithium limiter in a magnetic fusion device, and its effect on improving plasma performance by reducing particle recycling. Using large area liquid metal surfaces in any major fusion device is unlikely before a test on a smaller scale. This has motivated its demonstration in the CDX-U spherical torus with a unique, fully toroidal lithium limiter. The highest current discharges were obtained with a liquid lithium limiter. There was a reduction in recycling, as indicated by a significant decrease in the deuterium-alpha emission and oxygen radiation. How these results might extrapolate to reactors is suggested in recycling/retention experiments with liquid lithium surfaces under high-flux deuterium and helium plasma bombardment in PISCES-B. Data on deuterium atoms retained in liquid lithium indicate retention of all incident ions until full volumetric conversion to lithium deuteride. The PISCES-B results also show a material loss mechanism that lowers the maximum operating temperature compared to that for the liquid surface equilibrium vapor pressure. This may restrict the lithium temperature in reactors.

  16. Cell surface engineering of yeast for applications in white biotechnology.

    PubMed

    Kuroda, Kouichi; Ueda, Mitsuyoshi

    2011-01-01

    Cell surface engineering is a promising strategy for the molecular breeding of whole-cell biocatalysts. By using this strategy, yeasts can be constructed by the cell surface display of functional proteins; these yeasts are referred to as arming yeasts. Because reactions using arming yeasts as whole-cell biocatalysts occur on the cell surface, materials that cannot enter the cell can be used as reaction substrates. Numerous arming yeasts have therefore been constructed for a wide range of uses such as biofuel production, synthesis of valuable chemicals, adsorption or degradation of environmental pollutants, recovery of rare metal ions, and biosensors. Here, we review the science of yeast cell surface modification as well as current applications and future opportunities.

  17. Full Elastic Waveform Search Engine for Near Surface Imaging

    NASA Astrophysics Data System (ADS)

    Zhang, J.; Zhang, X.

    2014-12-01

    For processing land seismic data, the near-surface problem is often very complex and may severely affect our capability to image the subsurface. The current state-of-the-art technology for near surface imaging is the early arrival waveform inversion that solves an acoustic wave-equation problem. However, fitting land seismic data with acoustic wavefield is sometimes invalid. On the other hand, performing elastic waveform inversion is very time-consuming. Similar to a web search engine, we develop a full elastic waveform search engine that includes a large database with synthetic elastic waveforms accounting for a wide range of interval velocity models in the CMP domain. With each CMP gather of real data as an entry, the search engine applies Multiple-Randomized K-Dimensional (MRKD) tree method to find approximate best matches to the entry in about a second. Interpolation of the velocity models at CMP positions creates 2D or 3D Vp, Vs, and density models for the near surface area. The method does not just return one solution; it gives a series of best matches in a solution space. Therefore, the results can help us to examine the resolution and nonuniqueness of the final solution. Further, this full waveform search method can avoid the issues of initial model and cycle skipping that the method of full waveform inversion is difficult to deal with.

  18. Pulsed and continuous wave acrylic acid radio frequency plasma deposits: plasma and surface chemistry.

    PubMed

    Voronin, Sergey A; Zelzer, Mischa; Fotea, Catalin; Alexander, Morgan R; Bradley, James W

    2007-04-05

    Plasma polymers have been formed from acrylic acid using a pulsed power source. An on-pulse duration of 100 micros was used with a range of discharge off-times between 0 (continuous wave) and 20,000 micros. X-ray photoelectron spectroscopy (XPS) has been used in combination with trifluoroethanol (TFE) derivatization to quantify the surface concentration of the carboxylic acid functionality in the deposit. Retention of this functionality from the monomer varied from 2% to 65%. When input power was expressed as the time-averaged energy per monomer molecule, E(mean), the deposit chemistry achieved could be described using a single relationship for all deposition conditions. Deposition rates were monitored using a quartz crystal microbalance, which revealed a range from 20 to 200 microg m(-2) s(-1), and these fell as COOH functional retention increased. The flow rate was found to be the major determinant of the deposition rate, rather than being uniquely defined by E(mean), connected to the rate at which fresh monomer enters the system in the monomer deficient regime. The neutral species were collected in a time-averaged manner. As the energy delivered per molecule in the system (E(mean)) decreased, the amount of intact monomer increased, with the average neutral mass approaching 72 amu as E(mean) tends to zero. No neutral oligomeric species were detected. Langmuir probes have been used to determine the temporal evolution of the density and temperature of the electrons in the plasma and the plasma potential adjacent to the depositing film. It has been found that even 500 micros into the afterglow period that ionic densities are still significant, 5-10% of the on-time density, and that ion accelerating sheath potentials fall from 40 V in the on-time to a few volts in the off-time. We have made the first detailed, time- and energy-resolved mass spectrometry measurements in depositing acrylic acid plasma. These have allowed us to identify and quantify the positive ion

  19. Surface modification of argon/oxygen plasma treated vulcanized ethylene propylene diene polymethylene surfaces for improved adhesion with natural rubber

    NASA Astrophysics Data System (ADS)

    Basak, Ganesh C.; Bandyopadhyay, Abhijit; Neogi, Sudarsan; Bhowmick, Anil K.

    2011-01-01

    Vulcanized ethylene propylene diene polymethylene (EPDM) rubber surface was treated in a radio frequency capacitatively coupled low pressure argon/oxygen plasma to improve adhesion with compounded natural rubber (NR) during co-vulcanization. The plasma modified surfaces were analyzed by means of contact angle measurement, surface energy, attenuated total reflection-infrared spectroscopy, X-ray photoelectron spectroscopy, scanning electron microscopy, energy dispersive X-ray sulfur mapping and atomic force microscopy. Several experimental variables such as plasma power, length of exposure time and composition of the argon-oxygen gas mixture were considered. It was delineated that plasma treatment changed both surface composition and roughness, and consequently increased peel strength. The change in surface composition was mainly ascribed to the formation of C-O and -Cdbnd O functional groups on the vulcanized surfaces. A maximum of 98% improvement in peel strength was observed after plasma treatment.

  20. Surface damage characteristics of CFC and tungsten with repetitive ELM-like pulsed plasma irradiation

    NASA Astrophysics Data System (ADS)

    Kikuchi, Y.; Nishijima, D.; Nakatsuka, M.; Ando, K.; Higashi, T.; Ueno, Y.; Ishihara, M.; Shoda, K.; Nagata, M.; Kawai, T.; Ueda, Y.; Fukumoto, N.; Doerner, R. P.

    2011-08-01

    Surface damage of carbon fiber composite (CFC) and tungsten (W) due to repetitive ELM-like pulsed plasma irradiation has been investigated by using a magnetized coaxial plasma gun. CX2002U CFC and stress-relieved W samples were exposed to repetitive pulsed deuterium plasmas with duration of ˜0.5 ms, incident ion energy of ˜30 eV, and surface absorbed energy density of ˜0.3-0.7 MJ/m2. Bright spots on a CFC surface during pulsed plasma exposures were clearly observed with a high-speed camera, indicating a local surface heating. No melting of a W surface was observed under a single plasma pulse exposure at energy density of ˜0.7 MJ/m2, although cracks were formed. Cracking of the W surface grew with repetitive pulsed plasma exposures. Subsequently, the surface melted due to localized heat absorption.

  1. Strongly Enhanced Laser Absorption and Electron Acceleration via Resonant Excitation of Surface Plasma Waves

    NASA Astrophysics Data System (ADS)

    Raynaud, M.; Riconda, C.; Adam, J. C.; Heron, A.

    2010-02-01

    The possibility of creating enhanced fast electron bunches via the excitation of surface plasma waves (SPW) in laser overdense plasma interaction has been investigated by mean of relativistic one dimension motion of a test electron in the field of the surface plasma wave study and with two-dimensional (2D) Particle-In-Cell (PIC) numerical simulations. Strong electron acceleration together with a dramatic increase, up to 70%, of light absorption by the plasma is observed.

  2. Controllable surface morphology and properties via mist polymerization on a plasma-treated polymethyl methacrylate surface.

    PubMed

    Wan, S J; Wang, L; Xu, X J; Zhao, C H; Liu, X D

    2014-02-14

    Surface modification by grafting polymers on solid materials is an important strategy used to improve surface properties. This article reports that under appropriate conditions, very thin layers with desired morphologies may be constructed on a plasma-treated substrate by feeding a small quantity of a monomer with a mist stream carrying droplets produced from monomer solutions. We investigate the effects of process parameters that affect layer morphology, including exposure time to the mist stream, concentration of the monomer solution, and solvent selectivity. For a methyl methacrylate solution in ethanol, nanoparticles are uniformly grown with increasing monomer concentration or exposure time and finally form a porous layer at 3.65 mol L(-1) for 30 min. Decreasing solvent polarity not only affects surface morphology, but also increases hydrophobicity of the resulting surface. With 2,2,3,4,4,4-hexafluorobutyl methacrylate as the monomer, SEM and AFM micrographs indicated that mist polymerization results in numerous microspheres on the activated surface. These experimental results were interpreted by a mechanism in terms of an in situ polymerization accompanied by a phase transformation of the resulting polymer. Specifically, plasma treatment provides highly active cations and radicals to initiate very rapid polymerization, and the resulting polymers are consequently deposited from the liquid onto the surface under phase transition mechanisms.

  3. Plasma-assisted heterogeneous catalysis for NOx reduction in lean-burn engine exhaust

    SciTech Connect

    Penetrante, B.M.; Hsaio, M.C.; Merritt, B.T.; Vogtlin, G.E.; Wan, C.Z.; Rice, G.W.; Voss, K.E.

    1997-12-31

    This paper discusses the combination of a plasma with a catalyst to improve the reduction of NO{sub x} under lean-burn conditions. The authors have been investigating the effects of a plasma on the NO{sub x} reduction activity and temperature operating window of various catalytic materials. One of the goals is to develop a fundamental understanding of the interaction between the gas-phase plasma chemistry and the heterogeneous chemistry on the catalyst surface. The authors have observed that plasma assisted heterogeneous catalysis can facilitate NO{sub x} reduction under conditions that normally make it difficult for either the plasma or the catalyst to function by itself. By systematically varying the plasma electrode and catalyst configuration, they have been able to elucidate the process by which the plasma chemistry affects the chemical reduction of NO{sub x} on the catalyst surface. They have discovered that the main effect of the plasma is to induce the gas-phase oxidation of NO to NO{sub 21}. The reduction of NO{sub x} to N{sub 2} is then accomplished by heterogeneous reaction of O with activated hydrocarbons on the catalyst surface. The use of a plasma opens the opportunity for a new class of catalysts that are potentially more durable, more active, more selective and more sulfur-tolerant compared to conventional lean-NO{sub x} catalysts.

  4. Surface Engineering of Nanostructured Titanium Implants with Bioactive Ions.

    PubMed

    Kim, H-S; Kim, Y-J; Jang, J-H; Park, J-W

    2016-05-01

    Surface nanofeatures and bioactive ion chemical modification are centrally important in current titanium (Ti) oral implants for enhancing osseointegration. However, it is unclear whether the addition of bioactive ions definitively enhances the osteogenic capacity of a nanostructured Ti implant. We systematically investigated the osteogenesis process of human multipotent adipose stem cells triggered by bioactive ions in the nanostructured Ti implant surface. Here, we report that bioactive ion surface modification (calcium [Ca] or strontium [Sr]) and resultant ion release significantly increase osteogenic activity of the nanofeatured Ti surface. We for the first time demonstrate that ion modification actively induces focal adhesion development and expression of critical adhesion–related genes (vinculin, talin, and RHOA) of human multipotent adipose stem cells, resulting in enhanced osteogenic differentiation on the nanofeatured Ti surface. It is also suggested that fibronectin adsorption may have only a weak effect on early cellular events of mesenchymal stem cells (MSCs) at least in the case of the nanostructured Ti implant surface incorporating Sr. Moreover, results indicate that Sr overrides the effect of Ca and other important surface factors (i.e., surface area and wettability) in the osteogenesis function of various MSCs (derived from human adipose, bone marrow, and murine bone marrow). In addition, surface engineering of nanostructured Ti implants using Sr ions is expected to exert additional beneficial effects on implant bone healing through the proper balancing of the allocation of MSCs between adipogenesis and osteogenesis. This work provides insight into the future surface design of Ti dental implants using surface bioactive ion chemistry and nanotopography.

  5. Biological surface engineering: a simple system for cell pattern formation.

    PubMed

    Zhang, S; Yan, L; Altman, M; Lässle, M; Nugent, H; Frankel, F; Lauffenburger, D A; Whitesides, G M; Rich, A

    1999-07-01

    Biological surface engineering using synthetic biological materials has a great potential for advances in our understanding of complex biological phenomena. We developed a simple system to engineer biologically relevant surfaces using a combination of self-assembling oligopeptide monolayers and microcontact printing (muCP). We designed and synthesized two oligopeptides containing a cell adhesion motif (RADS)n (n = 2 and 3) at the N-terminus, followed by an oligo(alanine) linker and a cysteine residue at the C-terminus. The thiol group of cysteine allows the oligopeptides to attach covalently onto a gold-coated surface to form monolayers. We then microfabricated a variety of surface patterns using the cell adhesion peptides in combination with hexa-ethylene glycol thiolate which resist non-specific adsorption of proteins and cells. The resulting patterns consist of areas either supporting or inhibiting cell adhesion, thus they are capable of aligning cells in a well-defined manner, leading to specific cell array and pattern formations.

  6. Engineering biomaterials surfaces to modulate the host response.

    PubMed

    Yu, Kai; Mei, Yan; Hadjesfandiari, Narges; Kizhakkedathu, Jayachandran N

    2014-12-01

    Undesirable host response is responsible for the surface induced thrombus generation, activation of the complement system and the inflammatory reactions by the blood-contacting biomaterials. The surface interaction of biomaterials with different blood components is thought to be the critical factor that dictates the host response to biomaterials. Surface engineering can be utilized as a method to enhance the biocompatibility and tailor the biological response to biomaterials. This review provides a brief account of various polymer brush based approaches used for biomaterials surface modification, both passive and bioactive, to make the material surfaces biocompatible and antibacterial. Initially we discuss the utilization of polymer brushes with different structure and chemistry as a novel strategy to design the surface non-fouling that passively prevent the subsequent biological responses. Further we explore the utility of different bioactive agents including peptides, carbohydrates and proteins which can be conjugated the polymer brush to make the surface actively interact with the body and modulate the host response. A number of such avenues have also been explored in this review.

  7. Engineering chemical reactivity on cell surfaces through oligosaccharide biosynthesis

    SciTech Connect

    Mahal, L.K.; Yareme, K.J.; Bertozzi, C.R.

    1997-05-16

    Cell surface oligosaccharide can be engineered to display unusual functional groups for the selective chemical remodeling of cell surfaces. An unnatural derivative of N-acetyl-mannosamine, which has a ketone group, was converted to the corresponding sialic acid and incorporated into cell surface oligosaccharide metabolically, resulting in the cell surface display of ketone groups. The ketone group on the cell surface can then be covalently ligated under physiological conditions with molecules carrying a complementary reactive functional group such as the hydrazide. Cell surface reactions of this kind should prove useful in the introduction of new recognition epitopes, such as peptides, oligosaccharide, or small organic molecules, onto cell surfaces and in the subsequent modulation of cell-cell or cell-small molecule binding events. The versatility of this technology was demonstrated by an example of selective drug delivery. Cells were decorated with biotin through selective conjugation to ketone groups, and selectively killed in the presence of a ricin A chain-avidin conjugate. 30 refs., 4 figs.

  8. A Cascaded Discharge Plasma-Adsorbent Technique for Engine Exhaust Treatment

    NASA Astrophysics Data System (ADS)

    Rajanikanth, B. S.; Srinivasan, A. D.; Arya, Nandiny B.

    2003-06-01

    A cascaded system of electrical discharges (non-thermal plasma) and adsorption process was investigated for the removal of oxides of Nitrogen (NOx) and total hydrocarbons (THC) from an actual diesel engine exhaust. The non-thermal plasma and adsorption processes were separately studied first and then the cascaded process was studied. In this study, different types of adsorbents were used. The NOx removal efficiency was higher with plasma-associated adsorption (cascaded) process compared to the individual processes and the removal efficiency was found almost invariant in time. When associated by plasma, among the adsorbents studied, activated charcoal and MS-13X were more effective for NOx and THC removal respectively. The experiments were conducted at no load and at 50% load conditions. The plasma reactor was kept at room temperature throughout the experiment, while the temperature of the adsorbent reactor was varied. A relative comparison of adsorbents was discussed at the end.

  9. Characterization of the human plasma phosphoproteome using linear ion trap mass spectrometry and multiple search engines.

    PubMed

    Carrascal, Montserrat; Gay, Marina; Ovelleiro, David; Casas, Vanessa; Gelpí, Emilio; Abian, Joaquin

    2010-02-05

    Major plasma protein families play different roles in blood physiology and hemostasis and in immunodefense. Other proteins in plasma can be involved in signaling as chemical messengers or constitute biological markers of the status of distant tissues. In this respect, the plasma phosphoproteome holds potentially relevant information on the mechanisms modulating these processes through the regulation of protein activity. In this work we describe for the first time a collection of phosphopeptides identified in human plasma using immunoaffinity separation of the seven major serum protein families from other plasma proteins, SCX fractionation, and TiO(2) purification prior to LC-MS/MS analysis. One-hundred and twenty-seven phosphosites in 138 phosphopeptides mapping 70 phosphoproteins were identified with FDR < 1%. A high-confidence collection of phosphosites was obtained using a combined search with the OMSSA, SEQUEST, and Phenyx search engines.

  10. Cold atmospheric plasma (CAP) surface nanomodified 3D printed polylactic acid (PLA) scaffolds for bone regeneration.

    PubMed

    Wang, Mian; Favi, Pelagie; Cheng, Xiaoqian; Golshan, Negar H; Ziemer, Katherine S; Keidar, Michael; Webster, Thomas J

    2016-12-01

    Three-dimensional (3D) printing is a new fabrication method for tissue engineering which can precisely control scaffold architecture at the micron-scale. However, scaffolds not only need 3D biocompatible structures that mimic the micron structure of natural tissues, they also require mimicking of the nano-scale extracellular matrix properties of the tissue they intend to replace. In order to achieve this, the objective of the present in vitro study was to use cold atmospheric plasma (CAP) as a quick and inexpensive way to modify the nano-scale roughness and chemical composition of a 3D printed scaffold surface. Water contact angles of a normal 3D printed poly-lactic-acid (PLA) scaffold dramatically dropped after CAP treatment from 70±2° to 24±2°. In addition, the nano-scale surface roughness (Rq) of the untreated 3D PLA scaffolds drastically increased (up to 250%) after 1, 3, and 5min of CAP treatment from 1.20nm to 10.50nm, 22.90nm, and 27.60nm, respectively. X-ray photoelectron spectroscopy (XPS) analysis showed that the ratio of oxygen to carbon significantly increased after CAP treatment, which indicated that the CAP treatment of PLA not only changed nano-scale roughness but also chemistry. Both changes in hydrophilicity and nano-scale roughness demonstrated a very efficient plasma treatment, which in turn significantly promoted both osteoblast (bone forming cells) and mesenchymal stem cell attachment and proliferation. These promising results suggest that CAP surface modification may have potential applications for enhancing 3D printed PLA bone tissue engineering materials (and all 3D printed materials) in a quick and an inexpensive manner and, thus, should be further studied.

  11. An Integrated Surface Engineering Technology Development for Improving Energy Efficiency of Engine Components

    SciTech Connect

    Stephen Hsu; Liming Chang; Huan Zhan

    2009-05-31

    Frictional losses are inherent in most practical mechanical systems. The ability to control friction offers many opportunities to achieve energy conservation. Over the years, materials, lubricants, and surface modifications have been used to reduce friction in automotive and diesel engines. However, in recent years, progress in friction reduction technology has slowed because many of the inefficiencies have been eliminated. A new avenue for friction reduction is needed. Designing surfaces specifically for friction reduction with concomitant enhanced durability for various engine components has emerged recently as a viable opportunity due to advances in fabrication and surface finishing techniques. Recently, laser ablated dimples on surfaces have shown friction reduction properties and have been demonstrated successfully in conformal contacts such as seals where the speed is high and the load is low. The friction reduction mechanism in this regime appears to depend on the size, patterns, and density of dimples in the contact. This report describes modeling efforts in characterizing surface textures and understanding their mechanisms for enhanced lubrication under high contact pressure conditions. A literature survey is first presented on the development of descriptors for irregular surface features. This is followed by a study of the hydrodynamic effects of individual micro-wedge dimples using the analytical solution of the 1-D Reynolds equation and the determination of individual components of the total friction resistance. The results obtained provide a better understanding of the dimple orientation effects and the approach which may be used to further compare the friction reduction provided by different texture patterns.

  12. Surface modification of polymers by atomic oxygen using ECR plasma

    NASA Astrophysics Data System (ADS)

    Abdul majeed, Riyadh M. A.; Datar, A.; Bhoraskar, S. V.; Bhoraskar, V. N.

    2007-05-01

    Polyimide (PI) and fluorinated ethylene propylene (FEP) samples were exposed to atomic oxygen ions of average energy ˜12 eV and flux ˜5 × 10 13 ions cm -2 s -1, produced in an ECR plasma. The fluence of the oxygen ions was varied from sample to sample over a range from ˜5 × 10 16 to 2 × 10 17 ions cm -2. The pre- and the post-irradiated samples were characterized by the contact angle, AFM and XPS techniques. The results indicate that the surface roughness of the polyimide increased from ˜7 to ˜65 nm, that of the FEP from ˜5 to ˜28 nm and the surface regions of both polyimide and FEP changed from hydrophobic to hydrophilic after exposure to atomic oxygen ions. The XPS results reveal that the concentrations of carbon, fluorine and oxygen changed even at a fluence of ˜10 17 ions cm -2 of the atomic oxygen ions. The results of the present study reveal that significant changes have been induced in the surface morphology and adhesion properties of polyimide and FEP after exposure to atomic oxygen ions.

  13. 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.

  14. Covalent immobilization of liposomes on plasma functionalized metallic surfaces.

    PubMed

    Mourtas, S; Kastellorizios, M; Klepetsanis, P; Farsari, E; Amanatides, E; Mataras, D; Pistillo, B R; Favia, P; Sardella, E; d'Agostino, R; Antimisiaris, S G

    2011-05-01

    A method was developed to functionalize biomedical metals with liposomes. The novelty of the method includes the plasma-functionalization of the metal surface with proper chemical groups to be used as anchor sites for the covalent immobilization of the liposomes. Stainless steel (SS-316) disks were processed in radiofrequency glow discharges fed with vapors of acrylic acid to coat them with thin adherent films characterized by surface carboxylic groups, where liposomes were covalently bound through the formation of amide bonds. For this, liposomes decorated with polyethylene glycol molecules bearing terminal amine-groups were prepared. After ensuring that the liposomes remain intact, under the conditions applying for immobilization; different attachment conditions were evaluated (incubation time, concentration of liposome dispersion) for optimization of the technique. Immobilization of calcein-entrapping liposomes was evaluated by monitoring the percent of calcein attached on the surfaces. Best results were obtained when liposome dispersions with 5mg/ml (liposomal lipid) concentration were incubated on each disk for 24h at 37°C. The method is proposed for developing drug-eluting biomedical materials or devices by using liposomes that have appropriate membrane compositions and are loaded with drugs or other bioactive agents.

  15. Front surface structured targets for enhancing laser-plasma interactions

    NASA Astrophysics Data System (ADS)

    Snyder, Joseph; George, Kevin; Ji, Liangliang; Yalamanchili, Sasir; Simonoff, Ethan; Cochran, Ginevra; Daskalova, Rebecca; Poole, Patrick; Willis, Christopher; Lewis, Nathan; Schumacher, Douglass

    2016-10-01

    We present recent progress made using front surface structured interfaces for enhancing ultrashort, relativistic laser-plasma interactions. Structured targets can increase laser absorption and enhance ion acceleration through a number of mechanisms such as direct laser acceleration and laser guiding. We detail experimental results obtained at the Scarlet laser facility on hollow, micron-scale plasma channels for enhancing electron acceleration. These targets show a greater than three times enhancement in the electron cutoff energy as well as an increased slope temperature for the electron distribution when compared to a flat interface. Using three-dimensional particle-in-cell (PIC) simulations, we have modeled the interaction to give insight into the physical processes responsible for the enhancement. Furthermore, we have used PIC simulations to design structures that are more advantageous for ion acceleration. Such targets necessitate advanced target fabrication methods and we describe techniques used to manufacture optimized structures, including vapor-liquid-solid growth, cryogenic etching, and 3D printing using two-photon-polymerization. This material is based upon work supported by the Air Force Office of Scientific Research under Award Number FA9550-14-1-0085.

  16. Plasma conversion of methane into higher hydrocarbons at surfaces

    SciTech Connect

    Sackinger, W.M.; Kamath, V.A.

    1995-12-31

    Natural gas is widely abundant, is easily withdrawn from reservoirs, is commonly produced as an associated gas along with crude oil production, and is found in many geologic settings as a resource separate from oil. A much larger fraction of the natural gas may be produced from a gas reservoir, as compared with a crude oil reservoir. However, natural gas is normally transported by pipeline, and the energy throughput of such a pipeline is perhaps only 20% to 30% of the throughput of an oil pipeline of the same size and cost. Gas is difficult to transport in moderate quantities at low cost, as it must either have a special pipeline or must be liquified into LNG, shipped in cryogenic LNG tankers, and regasified chemical stability of methane has made it difficult to convert it directly into conventional hydrocarbon fuel mixtures, and has also impeded its use as a feedstock for petrochemical production. Experiments are described in which a methane plasma is created, and the resulting methyl and hydrogen ions have been accelerated within a microchannel array so that they interact with neutral methane molecules on the inside surfaces of the microchannels. No catalysts are used, and the device operates at room temperature. Impact energies of the ions are in the range of 15 ev to greater than 100 ev, and the energy delivered in the interaction at the surfaces has caused the production of larger hydrocarbon molecules, such as C{sub 2}H{sub 2}, C{sub 2}H{sub 4}, and C{sub 2}H{sub 6}, along with C{sub 3}, C{sub 4}, C{sub 5}, C{sub 6}, C{sub 7}, and C{sub 8} molecules. Conversion effectiveness is greater at higher pressure, due to the increased ionic activity. The costs of production of the plasma conversion devices are projected to be quite low, and the technology appears to be commercially and economically feasible.

  17. Scaffolds for hand tissue engineering: the importance of surface topography.

    PubMed

    Kloczko, E; Nikkhah, D; Yildirimer, L

    2015-11-01

    Tissue engineering is believed to have great potential for the reconstruction of the hand after trauma, congenital absence and tumours. Due to the presence of multiple distinct tissue types, which together function in a precisely orchestrated fashion, the hand counts among the most complex structures to regenerate. As yet the achievements have been limited. More recently, the focus has shifted towards scaffolds, which provide a three-dimensional framework to mimic the natural extracellular environment for specific cell types. In particular their surface structures (or topographies) have become a key research focus to enhance tissue-specific cell attachment and growth into fully functioning units. This article reviews the current understanding in hand tissue engineering before focusing on the potential for scaffold topographical features on micro- and nanometre scales to achieve better functional regeneration of individual and composite tissues.

  18. Directional transport of impinging capillary jet on wettability engineered surfaces

    NASA Astrophysics Data System (ADS)

    Ghosh, Aritra; Chatterjee, Souvick; Sinha Mahapatra, Pallab; Ganguly, Ranjan; Megaridis, Constantine

    2015-11-01

    Impingement of capillary jet on a surface is important for applications like heat transfer, or for liquid manipulation in bio-microfluidic devices. Using wettability engineered surfaces, we demonstrate pump-less and directional transport of capillary jet on a flat surface. Spatial contrast of surface energy and a wedge-shape geometry of the wettability confined track on the substrate facilitate formation of instantaneous spherical bulges upon jet impingement; these bulges are further transported along the superhydrophilic tracks due to Laplace pressure gradient. Critical condition warranted for formation of liquid bulge along the varying width of the superhydrophilic track is calculated analytically and verified experimentally. The work throws light on novel fluid phenomena of unidirectional jet impingement on wettability confined surfaces and provides a platform for innovative liquid manipulation technique for further application. By varying the geometry and wettability contrast on the surface, one can achieve volume flow rates of ~ O(100 μL/sec) and directionally guided transport of the jet liquid, pumplessly at speeds of ~ O(10cm/sec).

  19. Automating laser scanning of 3D surfaces for reverse engineering

    NASA Astrophysics Data System (ADS)

    Chan, Vincent H.; Bradley, Colin H.; Vickers, Geoffrey W.

    1997-12-01

    Application of current 3-D laser scanning systems to reverse engineering is limited by two obstacles. The meticulous guidance of the laser scanner over the surface of the object being scanned and the segmentation of the cloud data which is collected by the laser scanner. Presently, both obstacles are being manually solved. The guidance of the laser scanning sensor at the correct surface to sensor distance is dependent on operator judgement and the segmentation of the collected data is reliant on the user to manually define surface boundaries on a computer screen. By applying a 2-D CCD camera, both of these problems can be resolved. Depth information on the location of the object surface can be derived from a pair of stereo images from the CCD camera. Using this depth information, the scanner path can be automatically calculated. Segmentation of the object surface can be accomplished by employing a Kohonen neural network into the CCD image. Successful segmentation of the image is conditional on the locations selected to start neural nodes as well as the prevention of the neuron connectors from bleeding onto neighboring patches. Thus the CCD camera allows for the automatic path planning of the laser scanner as well as the segmentation of the surface into patches defined along its natural boundaries.

  20. Ground Simulations of Near-Surface Plasma Field and Charging at the Lunar Terminator

    NASA Astrophysics Data System (ADS)

    Polansky, J.; Ding, N.; Wang, J.; Craven, P.; Schneider, T.; Vaughn, J.

    2012-12-01

    Charging in the lunar terminator region is the most complex and is still not well understood. In this region, the surface potential is sensitively influenced by both solar illumination and plasma flow. The combined effects from localized shadow generated by low sun elevation angles and localized wake generated by plasma flow over the rugged terrain can generate strongly differentially charged surfaces. Few models currently exist that can accurately resolve the combined effects of plasma flow and solar illumination over realistic lunar terminator topographies. This paper presents an experimental investigation of lunar surface charging at the terminator region in simulated plasma environments in a vacuum chamber. The solar wind plasma flow is simulated using an electron bombardment gridded Argon ion source. An electrostatic Langmuir probe, nude Faraday probes, a floating emissive probe, and retarding potential analyzer are used to quantify the plasma flow field. Surface potentials of both conducting and dielectric materials immersed in the plasma flow are measured with a Trek surface potential probe. The conducting material surface potential will simultaneously be measured with a high impedance voltmeter to calibrate the Trek probe. Measurement results will be presented for flat surfaces and objects-on-surface for various angles of attack of the plasma flow. The implications on the generation of localized plasma wake and surface charging at the lunar terminator will be discussed. (This research is supported by the NASA Lunar Advanced Science and Exploration Research program.)

  1. T55-L-712 turbine engine compressor housing refurbishment-plasma spray project

    NASA Technical Reports Server (NTRS)

    Leissler, George W.; Yuhas, John S.

    1988-01-01

    A study was conducted to assess the feasibility of reclaiming T55-L-712 turbine engine compressor housings with an 88 wt percent aluminum to 12 wt percent silicon alloy applied by a plasma spray process. Tensile strength testing was conducted on as-sprayed and thermally cycled test specimens which were plasma sprayed with 0.020 to 0.100 in. coating thicknesses. Satisfactory tensile strength values were observed in the as-sprayed tensile specimens. There was essentially no decrease in tensile strength after thermally cycling the tensile specimens. Furthermore, compressor housings were plasma sprayed and thermally cycled in a 150-hr engine test and a 200-hr actual flight test during which the turbine engine was operated at a variety of loads, speeds and torques. The plasma sprayed coating system showed no evidence of degradation or delamination from the compressor housings. As a result of these tests, a procedure was designed and developed for the application of an aluminum-silicon alloy in order to reclaim T55-L-712 turbine engine compressor housings.

  2. Establishment of cell surface engineering and its development.

    PubMed

    Ueda, Mitsuyoshi

    2016-07-01

    Cell surface display of proteins/peptides has been established based on mechanisms of localizing proteins to the cell surface. In contrast to conventional intracellular and extracellular (secretion) expression systems, this method, generally called an arming technology, is particularly effective when using yeasts as a host, because the control of protein folding that is often required for the preparation of proteins can be natural. This technology can be employed for basic and applied research purposes. In this review, I describe various strategies for the construction of engineered yeasts and provide an outline of the diverse applications of this technology to industrial processes such as the production of biofuels and chemicals, as well as bioremediation and health-related processes. Furthermore, this technology is suitable for novel protein engineering and directed evolution through high-throughput screening, because proteins/peptides displayed on the cell surface can be directly analyzed using intact cells without concentration and purification. Functional proteins/peptides with improved or novel functions can be created using this beneficial, powerful, and promising technique.

  3. Plasma treatment induces internal surface modifications of electrospun poly(L-lactic) acid scaffold to enhance protein coating

    SciTech Connect

    Jin Seo, Hyok; Hee Lee, Mi; Kwon, Byeong-Ju; Kim, Hye-Lee; Park, Jong-Chul; Jin Lee, Seung; Kim, Bong-Jin; Wang, Kang-Kyun; Kim, Yong-Rok

    2013-08-21

    Advanced biomaterials should also be bioactive with regard to desirable cellular responses, such as selective protein adsorption and cell attachment, proliferation, and differentiation. To enhance cell-material interactions, surface modifications have commonly been performed. Among the various surface modification approaches, atmospheric pressure glow discharge plasma has been used to change a hydrophobic polymer surface to a hydrophilic surface. Poly(L-lactic acid) (PLLA)-derived scaffolds lack cell recognition signals and the hydrophobic nature of PLLA hinders cell seeding. To make PLLA surfaces more conducive to cell attachment and spreading, surface modifications may be used to create cell-biomaterial interfaces that elicit controlled cell adhesion and maintain differentiated phenotypes. In this study, (He) gaseous atmospheric plasma glow discharge was used to change the characteristics of a 3D-type polymeric scaffold from hydrophobic to hydrophilic on both the outer and inner surfaces of the scaffold and the penetration efficiency with fibronectin was investigated. Field-emission scanning electron microscope images showed that some grooves were formed on the PLLA fibers after plasma treatment. X-ray photoelectron spectroscopy data also showed chemical changes in the PLLA structure. After plasma treatment, -CN (285.76 eV) was increased in C1s and -NH{sub 2} (399.70 eV) was increased significantly and –N=CH (400.80 eV) and –NH{sub 3}{sup +} (402.05 eV) were newly appeared in N1s. These changes allowed fibronectin to penetrate into the PLLA scaffold; this could be observed by confocal microscopy. In conclusion, helium atmospheric pressure plasma treatment was effective in modifying the polymeric scaffold, making it hydrophilic, and this treatment can also be used in tissue engineering research as needed to make polymers hydrophilic.

  4. End-point immobilization of heparin on plasma-treated surface of electrospun polycarbonate-urethane vascular graft.

    PubMed

    Qiu, Xuefeng; Lee, Benjamin Li-Ping; Ning, Xinghai; Murthy, Niren; Dong, Nianguo; Li, Song

    2017-03-15

    Small-diameter synthetic vascular grafts have high failure rate due to primarily surface thrombogenicity, and effective surface chemical modification is critical to maintain the patency of the grafts. In this study, we engineered a small-diameter, elastic synthetic vascular graft with off-the-shelf availability and anti-thrombogenic activity. Polycarbonate-urethane (PCU), was electrospun to produce nanofibrous grafts that closely mimicked a native blood vessel in terms of structural and mechanical strength. To overcome the difficulty of adding functional groups to PCU, we explored various surface modification methods, and determined that plasma treatment was the most effective method to modify the graft surface with functional amine groups, which were subsequently employed to conjugate heparin via end-point immobilization. In addition, we confirmed in vitro that the combination of plasma treatment and end-point immobilization of heparin exhibited the highest surface density and correspondingly the highest anti-thrombogenic activity of heparin molecules. Furthermore, from an in vivo study using a rat common carotid artery anastomosis model, we showed that plasma-heparin grafts had higher patency rate at 2weeks and 4weeks compared to plasma-control (untreated) grafts. More importantly, we observed a more complete endothelialization of the luminal surface with an aligned, well-organized monolayer of endothelial cells, as well as more extensive graft integration in terms of vascularization and cell infiltration from the surrounding tissue. This work demonstrates the feasibility of electrospinning PCU as synthetic elastic material to fabricate nanofibrous vascular grafts, as well as the potential to endow desired functionalization to the graft surface via plasma treatment for the conjugation of heparin or other bioactive molecules.

  5. Plasma treatment induces internal surface modifications of electrospun poly(L-lactic) acid scaffold to enhance protein coating

    NASA Astrophysics Data System (ADS)

    Jin Seo, Hyok; Hee Lee, Mi; Kwon, Byeong-Ju; Kim, Hye-Lee; Jin Lee, Seung; Kim, Bong-Jin; Wang, Kang-Kyun; Kim, Yong-Rok; Park, Jong-Chul

    2013-08-01

    Advanced biomaterials should also be bioactive with regard to desirable cellular responses, such as selective protein adsorption and cell attachment, proliferation, and differentiation. To enhance cell-material interactions, surface modifications have commonly been performed. Among the various surface modification approaches, atmospheric pressure glow discharge plasma has been used to change a hydrophobic polymer surface to a hydrophilic surface. Poly(L-lactic acid) (PLLA)-derived scaffolds lack cell recognition signals and the hydrophobic nature of PLLA hinders cell seeding. To make PLLA surfaces more conducive to cell attachment and spreading, surface modifications may be used to create cell-biomaterial interfaces that elicit controlled cell adhesion and maintain differentiated phenotypes. In this study, (He) gaseous atmospheric plasma glow discharge was used to change the characteristics of a 3D-type polymeric scaffold from hydrophobic to hydrophilic on both the outer and inner surfaces of the scaffold and the penetration efficiency with fibronectin was investigated. Field-emission scanning electron microscope images showed that some grooves were formed on the PLLA fibers after plasma treatment. X-ray photoelectron spectroscopy data also showed chemical changes in the PLLA structure. After plasma treatment, -CN (285.76 eV) was increased in C1s and -NH2 (399.70 eV) was increased significantly and -N=CH (400.80 eV) and -NH3+ (402.05 eV) were newly appeared in N1s. These changes allowed fibronectin to penetrate into the PLLA scaffold; this could be observed by confocal microscopy. In conclusion, helium atmospheric pressure plasma treatment was effective in modifying the polymeric scaffold, making it hydrophilic, and this treatment can also be used in tissue engineering research as needed to make polymers hydrophilic.

  6. Wettability and XPS analyses of nickel-phosphorus surfaces after plasma treatment: An efficient approach for surface qualification in mechatronic processes

    NASA Astrophysics Data System (ADS)

    Vivet, L.; Joudrier, A.-L.; Bouttemy, M.; Vigneron, J.; Tan, K. L.; Morelle, J. M.; Etcheberry, A.; Chalumeau, L.

    2013-06-01

    Electroless nickel-high-phosphorus Ni-P plating is known for its physical properties. In case of electronic and mechatronic assembly processes achieved under ambient conditions the wettability of the Ni-P layer under ambient temperature and ambient air stays a point of surface quality investigation. This contribution will be devoted to the study of the surface properties of Ni-P films for which we performed air plasma treatment. We focus our attention on the evolution of the surface wettability, using the classical sessile drop technique. Interpreting the results with the OWRK model we extract the polar and disperse surface tension components from which we deduced typical evolution of the surface properties with the different treatment settings. By controlling the variations of the parameters of the plasma exposure we are able to change the responses of our Ni-P sample from total hydrophobic to total hydrophilic behaviours. All the intermediate states can be reached by adapting the treatment parameters. So it is demonstrated that the apparent Ni-P surface properties can be fully adapted and the surface setting can be well characterized by wettability measurements. To deep our knowledge of the surface modifications induced by plasma we performed parallel SEM and XPS analyses which provide informations on the structure and the chemical composition of the surface for each set of treatment parameters. Using this double approach we were able to propose a correlation between the evolution of surface chemical composition and surface wettability which are completely governed by the plasma treatment conditions. Chemical parameters as the elimination of the carbon contamination, the progressive surface oxidation, and the slight incorporation of nitrogen due to the air plasma interaction are well associated with the evolution of the wettability properties. So a complete engineering for the Ni-P surface preparation has been established. The sessile drop method can be

  7. Surface Josephson plasma waves in layered superconductors above the plasma frequency: evidence for a negative index of refraction.

    PubMed

    Golick, V A; Kadygrob, D V; Yampol'skii, V A; Rakhmanov, A L; Ivanov, B A; Nori, Franco

    2010-05-07

    We predict a new branch of surface Josephson plasma waves (SJPWs) in layered superconductors for frequencies higher than the Josephson plasma frequency. In this frequency range, the permittivity tensor components along and transverse to the layers have different signs, which is usually associated with negative refraction. However, for these frequencies, the bulk Josephson plasma waves cannot be matched with the incident and reflected waves in the vacuum, and, instead of the negative-refractive properties, abnormal surface modes appear within the frequency band expected for bulk modes. We also discuss the excitation of high-frequency SJPWs by means of the attenuated-total-reflection method.

  8. Light-Guided Surface Engineering for Biomedical Applications

    PubMed Central

    Jayagopal, Ashwath; Stone, Gregory P.; Haselton, Frederick R.

    2010-01-01

    Free radical species generated through fluorescence photobleaching have been reported to effectively couple a water-soluble species to surfaces containing electron-rich sites (1). In this report, we expand upon this strategy to control the patterned attachment of antibodies and peptides to surfaces for biosensing and tissue engineering applications. In the first application, we compare hydrophobic attachment and photobleaching methods to immobilize FITC-labeled anti-M13K07 bacteriophage antibodies to the SiO2 layer of a differential capacitive biosensor and to the polyester filament of a feedback-controlled filament array. On both surfaces, antibody attachment and function were superior to the previously employed hydrophobic attachment. Furthermore, a laser scanning confocal microscope could be used for automated, software-guided photoattachment chemistry. In a second application, the cell-adhesion peptide RGDS was site-specifically photocoupled to glass coated with fluorescein-conjugated poly(ethylene glycol). RGDS attachment and bioactivity were characterized by a fibroblast adhesion assay. Cell adhesion was limited to sites of RGDS photocoupling. These examples illustrate that fluorophore-based photopatterning can be achieved by both solution-phase fluorophores or surface-adhered fluorophores. The coupling preserves the bioactivity of the patterned species, is amenable to a variety of surfaces, and is readily accessible to laboratories with fluorescence imaging equipment. The flexibility offered by visible light patterning will likely have many useful applications in bioscreening and tissue engineering where the controlled placement of biomolecules and cells is critical, and should be considered as an alternative to chemical coupling methods. PMID:18314938

  9. Pharmaceutical and biomedical potential of surface engineered dendrimers.

    PubMed

    Satija, Jitendra; Gupta, Umesh; Jain, Narendra Kumar

    2007-01-01

    Dendrimers are hyperbranched, globular, monodisperse, nanometric polymeric architecture, having definite molecular weight, shape, and size (which make these an inimitable and optimum carrier molecule in pharmaceutical field). Dendritic architecture is having immense potential over the other carrier systems, particularly in the field of drug delivery because of their unique properties, such as structural uniformity, high purity, efficient membrane transport, high drug pay load, targeting potential, and good colloidal, biological, and shelf stability. Despite their enormous applicability in different areas, the inherent cytotoxicity, reticuloendothelial system (RES) uptake, drug leakage, immunogenicity, and hemolytic toxicity restricted their use in clinical applications, which is primarily associated with cationic charge present on the periphery due to amine groups. To overcome this toxic nature of dendrimers, some new types of nontoxic, biocompatible, and biodegradable dendrimers have been developed (e.g., polyester dendrimer, citric acid dendrimer, arginine dendrimer, carbohydrate dendrimers, etc.). The surface engineering of parent dendrimers is graceful and convenient strategy, which not only shields the positive charge to make this carrier more biomimetic but also improves the physicochemical and biological behavior of parent dendrimers. Thus, surface modification chemistry of parent dendrimers holds promise in pharmaceutical applications (such as solubilization, improved drug encapsulation, enhanced gene transfection, sustained and controlled drug release, intracellular targeting) and in the diagnostic field. Development of multifunctional dendrimer holds greater promise toward the biomedical applications because a number of targeting ligands determine specificity in the same manner as another type of group would secure stability in biological milieu and prolonged circulation, whereas others facilitate their transport through cell membranes. Therefore, as a

  10. Insoluble coatings for Stirling engine heat pipe condenser surfaces

    NASA Technical Reports Server (NTRS)

    Dussinger, Peter M.

    1993-01-01

    The work done by Thermacore, Inc., Lancaster, Pennsylvania, for the Phase 1, 1992 SBIR National Aeronautics and Space Administration Contract, 'Insoluble Coatings for Stirling Engine Heat Pipe Condenser Surfaces' is described. The work was performed between January 1992 and July 1992. Stirling heat engines are being developed for electrical power generation use on manned and unmanned earth orbital and planetary missions. Dish Stirling solar systems and nuclear reactor Stirling systems are two of the most promising applications of the Stirling engine electrical power generation technology. The sources of thermal energy used to drive the Stirling engine typically are non-uniform in temperature and heat flux. Liquid metal heat pipe receivers are used as thermal transformers and isothermalizers to deliver the thermal energy at a uniform high temperature to the heat input section of the Stirling engine. The use of a heat pipe receiver greatly enhances system efficiency and potential life span. One issue that is raised during the design phase of heat pipe receivers is the potential solubility corrosion of the Stirling engine heat input section by the liquid metal working fluid. This Phase 1 effort initiated a program to evaluate and demonstrate coatings, applied to nickel based Stirling engine heater head materials, that are practically 'insoluble' in sodium, potassium, and NaK. This program initiated a study of nickel aluminide as a coating and developed and demonstrated a heat pipe test vehicle that can be used to test candidate materials and coatings. Nickel 200 and nickel aluminide coated Nickel 200 were tested for 1000 hours at 800 C at a condensation heat flux of 25 W/sq cm. Subsequent analyses of the samples showed no visible sign of solubility corrosion of either coated or uncoated samples. The analysis technique, photomicrographs at 200X, has a resolution of better than 2.5 microns (.0001 in). The results indicate that the heat pipe environment is not directly

  11. Insoluble coatings for Stirling engine heat pipe condenser surfaces

    NASA Astrophysics Data System (ADS)

    Dussinger, Peter M.

    1993-09-01

    The work done by Thermacore, Inc., Lancaster, Pennsylvania, for the Phase 1, 1992 SBIR National Aeronautics and Space Administration Contract, 'Insoluble Coatings for Stirling Engine Heat Pipe Condenser Surfaces' is described. The work was performed between January 1992 and July 1992. Stirling heat engines are being developed for electrical power generation use on manned and unmanned earth orbital and planetary missions. Dish Stirling solar systems and nuclear reactor Stirling systems are two of the most promising applications of the Stirling engine electrical power generation technology. The sources of thermal energy used to drive the Stirling engine typically are non-uniform in temperature and heat flux. Liquid metal heat pipe receivers are used as thermal transformers and isothermalizers to deliver the thermal energy at a uniform high temperature to the heat input section of the Stirling engine. The use of a heat pipe receiver greatly enhances system efficiency and potential life span. One issue that is raised during the design phase of heat pipe receivers is the potential solubility corrosion of the Stirling engine heat input section by the liquid metal working fluid. This Phase 1 effort initiated a program to evaluate and demonstrate coatings, applied to nickel based Stirling engine heater head materials, that are practically 'insoluble' in sodium, potassium, and NaK. This program initiated a study of nickel aluminide as a coating and developed and demonstrated a heat pipe test vehicle that can be used to test candidate materials and coatings. Nickel 200 and nickel aluminide coated Nickel 200 were tested for 1000 hours at 800 C at a condensation heat flux of 25 W/sq cm. Subsequent analyses of the samples showed no visible sign of solubility corrosion of either coated or uncoated samples. The analysis technique, photomicrographs at 200X, has a resolution of better than 2.5 microns (.0001 in). The results indicate that the heat pipe environment is not directly

  12. ATF (Advanced Toroidal Facility) flux surfaces and related plasma effects

    SciTech Connect

    Colchin, R.J.; England, A.C.; Harris, J.H.; Hillis, D.L.; Jernigan, T.C.; Murakami, M.; Neilson, G.H.; Rome, J.A.; Saltmarsh, M.J.; Anderson, F.S.B.

    1989-01-01

    Flux surfaces in the Advanced Toroidal Facility (ATF) were mapped using an electron beam which was incident on a fluorescent screen. Islands were found at r/a greater than or equal to 0.6, indicating the existence of field errors. Failure of the island size to scale with magnetic field indicated that the islands were intrinsic to the coils. The source of the field errors was found to be uncompensated dipoles in the helical coil feeds. The electron temperature was observed to be very low in the vicinity of the islands. Modifications were made to the helical field buswork to eliminate the field errors, and the flux surfaces were again checked using an electron beam. Islands at r/a greater than or equal to 0.6 were found to be greatly reduced in size, with the residual island at /tau/ = 1/2 scaling to 1 cm at B = 1 T. Initial experiments indicate that the plasma operating space has been extended since the buswork modifications. 4 refs., 3 figs.

  13. Polymer films with surfaces unmodified and modified by non-thermal plasma as new substrates for cell adhesion.

    PubMed

    Borges, A M G; Benetoli, L O; Licínio, M A; Zoldan, V C; Santos-Silva, M C; Assreuy, J; Pasa, A A; Debacher, N A; Soldi, V

    2013-04-01

    The surface properties of biomaterials, such as wettability, polar group distribution, and topography, play important roles in the behavior of cell adhesion and proliferation. Gaseous plasma discharges are among the most common means to modify the surface of a polymer without affecting its properties. Herein, we describe the surface modification of poly(styrene) (PS) and poly(methyl methacrylate) (PMMA) films using atmospheric pressure plasma processing through exposure to a dielectric barrier discharge (DBD). After treatment the film surface showed significant changes from hydrophobic to hydrophilic as the water contact angle decreasing from 95° to 37°. All plasma-treated films developed more hydrophilic surfaces compared to untreated films, although the reasons for the change in the surface properties of PS and PMMA differed, that is, the PS showed chemical changes and in the case of PMMA they were topographical. Excellent adhesion and cell proliferation were observed in all films. In vitro studies employing flow cytometry showed that the proliferation of L929 cells was higher in the film formed by a 1:1 mixture of PS/PMMA, which is consistent with the results of a previous study. These findings suggest better adhesion of L929 onto the 1:1 PS/PMMA modified film, indicating that this system is a new candidate biomaterial for tissue engineering.

  14. Development of improved-durability plasma sprayed ceramic coatings for gas turbine engines

    NASA Technical Reports Server (NTRS)

    Sumner, I. E.; Ruckle, D. L.

    1980-01-01

    An investigation is reported of improving the durability of plasma sprayed ceramic coatings for the vane platforms in the JT9d turbofan engine. The program aims for reduced fuel consumption of commercial aircraft engines; the use of improved strain tolerant microstructures and control of the substrate temperature during coating application are being evaluated. The initial burner rig tests at temperatures up to 1010 C indicated that improvements in cyclic life greater than 20:1 over previous ceramic coatings were achieved. Three plasma sprayed coating systems applied to first stage vane platforms in the high pressure turbine were subjected to a 1000-cycle JT9D engine endurance test with only minor damage occurring to the coatings.

  15. Development of improved-durability plasma sprayed ceramic coatings for gas turbine engines

    NASA Technical Reports Server (NTRS)

    Sumner, I. E.; Ruckle, D. L.

    1980-01-01

    As part of a NASA program to reduce fuel consumption of current commercial aircraft engines, methods were investigated for improving the durability of plasma sprayed ceramic coatings for use on vane platforms in the JT9D turbofan engine. Increased durability concepts under evaluation include use of improved strain tolerant microstructures and control of the substrate temperature during coating application. Initial burner rig tests conducted at temperatures of 1010 C (1850 F) indicate that improvements in cyclic life greater than 20:1 over previous ceramic coating systems were achieved. Three plasma sprayed coating systems applied to first stage vane platforms in the high pressure turbine were subjected to a 100-cycle JT9D engine endurance test with only minor damage occurring to the coatings.

  16. Reduction of NOx and PM in marine diesel engine exhaust gas using microwave plasma

    NASA Astrophysics Data System (ADS)

    Balachandran, W.; FInst, P.; Manivannan, N.; Beleca, R.; Abbod, M.

    2015-10-01

    Abatement of NOx and particulate matters (PM) of marine diesel exhaust gas using microwave (MW) non-thermal plasma is presented in this paper. NOx mainly consist of NO and less concentration of NO2 in a typical two stoke marine diesel engine and microwave plasma generation can completely remove NO. MW was generated using two 2kW microwave sources and a saw tooth passive electrode. Passive electrode was used to generate high electric field region within microwave environment where high energetic electrons (1-3eV) are produced for the generation of non-thermal plasma (NTP). 2kW gen-set diesel exhaust gas was used to test our pilot-scale MW plasma reactor. The experimental results show that almost 100% removal of NO is possible for the exhaust gas flow rate of 60l/s. It was also shown that MW can significantly remove soot particles (PM, 10nm to 365nm) entrained in the exhaust gas of 200kW marine diesel engine with 40% engine load and gas flow rate of 130l/s. MW without generating plasma showed reduction up to 50% reduction of PM and with the plasma up to 90% reduction. The major challenge in these experiments was that igniting the desired plasma and sustaining it with passive electrodes for longer period (10s of minutes) as it required fine tuning of electrode position, which was influenced by many factors such as gas flow rate, geometry of reactor and MW power.

  17. Online Coupling of Flow-Field Flow Fractionation and Single Particle Inductively Coupled Plasma-Mass Spectrometry: Characterization of Nanoparticle Surface Coating Thickness and Aggregation State

    EPA Science Inventory

    Surface coating thickness and aggregation state have strong influence on the environmental fate, transport, and toxicity of engineered nanomaterials. In this study, flow-field flow fractionation coupled on-line with single particle inductively coupled plasma-mass spectrometry i...

  18. Improvement of early cell adhesion on Thai silk fibroin surface by low energy plasma.

    PubMed

    Amornsudthiwat, Phakdee; Mongkolnavin, Rattachat; Kanokpanont, Sorada; Panpranot, Joongjai; Wong, Chiow San; Damrongsakkul, Siriporn

    2013-11-01

    Low energy plasma has been introduced to treat the surface of Thai silk fibroin which should be enhanced for cell adhesion due to its native hydrophobic surface. Plasma surface treatment could introduce desirable hydrophilic functionalities on the surface without using any chemicals. In this work, nitrogen glow discharge plasma was generated by a low energy AC50Hz power supply system. The plasma operating conditions were optimized to reach the highest nitrogen active species by using optical emission spectroscopy. X-ray photoelectron spectroscopy (XPS) revealed that amine, hydroxyl, ether, and carboxyl groups were induced on Thai silk fibroin surface after plasma treatment. The results on Fourier transform infrared attenuated total reflection (FTIR-ATR) spectroscopy confirmed that the plasma treated effects were only on the outermost layer since there was no change in the bulk chemistry. The surface topography was insignificantly changed from the detection with atomic force microscopy (AFM). The plasma-treated effects were the improved surface wettability and cell adhesion. After a 90-s treatment, the water contact angle was at 20°, while the untreated surface was at 70°. The early cell adhesion of L929 mouse fibroblast was accelerated. L929 cells only took 3h to reach 100% cell adhesion on 90 s N2 plasma-treated surface, while there was less than 50% cell adhesion on the untreated Thai silk fibroin surface after 6h of culture. The cell adhesion results were in agreement with the cytoskeleton development. L929 F-actin was more evident on 90 s N2 plasma-treated surface than others. It could be concluded that a lower energy AC50Hz plasma system enhanced early L929 mouse fibroblast adhesion on Thai silk fibroin surface without any significant change in surface topography and bulk chemistry.

  19. Engineering aperiodic nanostructured surfaces for scattering-based optical devices

    NASA Astrophysics Data System (ADS)

    Lee, Yuk Kwan Sylvanus

    Novel optical devices such as biosensors, color displays and authentication devices can be obtained from the distinctive light scattering properties of resonant nanoparticles and nanostructured arrays. These arrays can be optimized through the choice of material, particle morphology and array geometry. In this thesis, by engineering the multi-frequency colorimetric responses of deterministic aperiodic nanostructured surfaces (DANS) with various spectral Fourier properties, I designed, fabricated and characterized scattering-based devices for optical biosensing and structural coloration applications. In particular, using analytical and numerical optimization, colorimetric biosensors are designed and fabricated with conventional electron beam lithography, and characterized using dark-field scattering imaging as well as image autocorrelation analysis of scattered intensity in the visible spectral range. These sensors, which consist of aperiodic surfaces ranging from quasi-periodic to pseudo-random structures with flat Fourier spectra, sustain highly complex structural resonances that enable a novel optical sensing approach beyond the traditional Bragg scattering. To this end, I have experimentally demonstrated that DANS with engineered structural colors are capable of detecting nanoscale protein monolayers with significantly enhanced sensitivity over periodic structures. In addition, different aperiodic arrays of gold (Au) nanoparticles are integrated with polydimethylsiloxane (PDMS) microfluidic structures by soft-lithographic micro-imprint techniques. Distinctive scattering spectral shifts and spatial modifications of structural color patterns in response to refractive index variations were simultaneously measured. The successful integration of DANS with microfluidics technology has introduced a novel opto-fluidic sensing platform for label-free and multiplexed lab-on-a-chip applications. Moreover, by studying the isotropic scattering properties of homogenized

  20. Plasma-Wave Terahertz Detection Mediated by Topological Insulators Surface States.

    PubMed

    Viti, Leonardo; Coquillat, Dominique; Politano, Antonio; Kokh, Konstantin A; Aliev, Ziya S; Babanly, Mahammad B; Tereshchenko, Oleg E; Knap, Wojciech; Chulkov, Evgueni V; Vitiello, Miriam S

    2016-01-13

    Topological insulators (TIs) represent a novel quantum state of matter, characterized by edge or surface-states, showing up on the topological character of the bulk wave functions. Allowing electrons to move along their surface, but not through their inside, they emerged as an intriguing material platform for the exploration of exotic physical phenomena, somehow resembling the graphene Dirac-cone physics, as well as for exciting applications in optoelectronics, spintronics, nanoscience, low-power electronics, and quantum computing. Investigation of topological surface states (TSS) is conventionally hindered by the fact that in most of experimental conditions the TSS properties are mixed up with those of bulk-states. Here, we activate, probe, and exploit the collective electronic excitation of TSS in the Dirac cone. By engineering Bi2Te(3-x)Sex stoichiometry, and by gating the surface of nanoscale field-effect-transistors, exploiting thin flakes of Bi2Te2.2Se0.8 or Bi2Se3, we provide the first demonstration of room-temperature terahertz (THz) detection mediated by overdamped plasma-wave oscillations on the "activated" TSS of a Bi2Te2.2Se0.8 flake. The reported detection performances allow a realistic exploitation of TSS for large-area, fast imaging, promising superb impacts on THz photonics.

  1. Measurement of Plasma Clotting Using Shear Horizontal Surface Acoustic Wave Sensor

    NASA Astrophysics Data System (ADS)

    Nagayama, Tatsuya; Kondoh, Jun; Oonishi, Tomoko; Hosokawa, Kazuya

    2013-07-01

    The monitoring of blood coagulation is important during operation. In this study, a shear horizontal surface acoustic wave (SH-SAW) sensor is applied to monitor plasma clotting. An SH-SAW sensor with a metallized surface for mechanical perturbation detection can detect plasma clotting. As plasma clotting is a gel formation reaction, the SH-SAW sensor detects viscoelastic property changes. On the other hand, an SH-SAW sensor with a free surface for electrical perturbation detection detects only the liquid mixing effect. No electrical property changes due to plasma clotting are obtained using this sensor. A planar electrochemical sensor is also used to monitor plasma clotting. In impedance spectral analysis, plasma clotting is measured. However, in the measurement of time responses, no differences between clotting and nonclotting are obtained. Therefore, the SH-SAW sensor is useful for monitoring plasma clotting.

  2. Strategies in biomimetic surface engineering of nanoparticles for biomedical applications

    NASA Astrophysics Data System (ADS)

    Gong, Yong-Kuan; Winnik, Françoise M.

    2012-01-01

    Engineered nanoparticles (NPs) play an increasingly important role in biomedical sciences and in nanomedicine. Yet, in spite of significant advances, it remains difficult to construct drug-loaded NPs with precisely defined therapeutic effects, in terms of release time and spatial targeting. The body is a highly complex system that imposes multiple physiological and cellular barriers to foreign objects. Upon injection in the blood stream or following oral administation, NPs have to bypass numerous barriers prior to reaching their intended target. A particularly successful design strategy consists in masking the NP to the biological environment by covering it with an outer surface mimicking the composition and functionality of the cell's external membrane. This review describes this biomimetic approach. First, we outline key features of the composition and function of the cell membrane. Then, we present recent developments in the fabrication of molecules that mimic biomolecules present on the cell membrane, such as proteins, peptides, and carbohydrates. We present effective strategies to link such bioactive molecules to the NPs surface and we highlight the power of this approach by presenting some exciting examples of biomimetically engineered NPs useful for multimodal diagnostics and for target-specific drug/gene delivery applications. Finally, critical directions for future research and applications of biomimetic NPs are suggested to the readers.

  3. Efficiency of surface cleaning by a glow discharge for plasma spraying coating

    NASA Astrophysics Data System (ADS)

    Kadyrmetov, A. M.; Kashapov, N. F.; Sharifullin, S. N.; Saifutdinov, A. I.; Fadeev, S. A.

    2016-06-01

    The article presents the results of experimental studies of the quality of cleaning steel surfaces by a glow discharge for plasma spraying. Shows the results of measurements of the angle of surface wetting and bond strength of the plasma coating to the surface treated. The dependence of the influence of the glow discharge power, chamber pressure, distance between the electrodes and the processing time of the surface on cleaning efficiency. Optimal fields of factors is found. It is shown increase joint strength coating and base by 30-80% as a result of cleaning the substrate surface by a glow discharge plasma spraying.

  4. Stability of Atmospheric-Pressure Plasma Induced Changes on Polycarbonate Surfaces

    NASA Technical Reports Server (NTRS)

    Sharma, Rajesh; Holcomb, Edward; Trigwell, Steve

    2006-01-01

    Polycarbonate films are subjected to plasma treatment in a number of applications such as improving adhesion between polycarbonate and silicon alloy in protective and optical coatings. The changes in surface chemistry due to plasma treatment have tendency to revert back. Thus stability of the plasma induced changes on polymer surfaces over desired time period is very important. The objective of this study was to examine the effect of ageing on atmospheric pressure helium-plasma treated polycarbonate (PC) sample as a function of treatment time. The ageing effects were studied over a period of 10 days. The samples were plasma treated for 0.5, 2, 5 and 10 minutes. Contact angle measurements were made to study surface energy changes. Modification of surface chemical structure was examined using, X-ray Photoelectron Spectroscopy (XPS). Contact angle measurements on untreated and plasma treated surfaces were made immediately, 24, 48, 72 and 96 hrs after treatment. Contact angle decreased from 93 deg for untreated sample to 30 deg for sample plasma treated for 10 minutes. After 10 days the contact angles for the 10 minute plasma treated sample increased to 67 deg, but it never reverted back to that of untreated surface. Similarly the O/C ratio increased from 0.136 for untreated sample to 0.321 for 10 minute plasma treated sample indication increase in surface energy.

  5. A highly stable nonbiofouling surface with well-packed grafted zwitterionic polysulfobetaine for plasma protein repulsion.

    PubMed

    Chang, Yung; Liao, Shih-Chieh; Higuchi, Akon; Ruaan, Ruoh-Chyu; Chu, Chih-Wei; Chen, Wen-Yih

    2008-05-20

    An ideal nonbiofouling surface for biomedical applications requires both high-efficient antifouling characteristics in relation to biological components and long-term material stability from biological systems. In this study we demonstrate the performance and stability of an antifouling surface with grafted zwitterionic sulfobetaine methacrylate (SBMA). The SBMA was grafted from a bromide-covered gold surface via surface-initiated atom transfer radical polymerization to form well-packed polymer brushes. Plasma protein adsorption on poly(sulfobetaine methacrylate) (polySBMA) grafted surfaces was measured with a surface plasmon resonance sensor. It is revealed that an excellent stable nonbiofouling surface with grafted polySBMA can be performed with a cycling test of the adsorption of three model proteins in a wide range of various salt types, buffer compositions, solution pH levels, and temperatures. This work also demonstrates the adsorption of plasma proteins and the adhesion of platelets from human blood plasma on the polySBMA grafted surface. It was found that the polySBMA grafted surface effectively reduces the plasma protein adsorption from platelet-poor plasma solution to a level superior to that of adsorption on a surface terminated with tetra(ethylene glycol). The adhesion and activation of platelets from platelet-rich plasma solution were not observed on the polySBMA grafted surface. This work further concludes that a surface with good hemocompatibility can be achieved by the well-packed surface-grafted polySBMA brushes.

  6. Surface Modification of Material by Irradiation of Low Power Atmospheric Pressure Plasma Jet

    NASA Astrophysics Data System (ADS)

    Akamatsu, Hiroshi; Ichikawa, Kazunori; Azuma, Kingo; Onoi, Masahiro

    2010-10-01

    Application of a low power atmospheric pressure plasma jet for surface modifications of acrylic, aluminum, and highly crystalline graphite has been carried out experimentally. The plasma jet was generated with batteries-driven high voltage modulator. The power consumed for the plasma generation was estimated to be 0.12 W. The plasma had hydroxyl radicals, which is known as a strong oxider from an observation of optical emission spectrum. After the irradiation of the plasma, the surfaces of acrylic and aluminum became to be hydrophilic from the compartment of contact angle of water on these surfaces. The surface of highly crystalline graphite irradiated by the plasma jet had oxygen-rich functional groups such as C-O, C = O, and O = C-O.

  7. Monitoring Surface Condition of Plasma Grid of a Negative Hydrogen Ion Source

    SciTech Connect

    Wada, M.; Kasuya, T.; Tokushige, S.; Kenmotsu, T.

    2011-09-26

    Surface condition of a plasma grid in a negative hydrogen ion source is controlled so as to maximize the beam current under a discharge operation with introducing Cs into the ion source. Photoelectric current induced by laser beams incident on the plasma grid can produce a signal to monitor the surface condition, but the signal detection can be easily hindered by plasma noise. Reduction in size of a detection electrode embedded in the plasma grid can improve signal-to-noise ratio of the photoelectric current from the electrode. To evaluate the feasibility of monitoring surface condition of a plasma gird by utilizing photoelectric effect, a small experimental setup capable of determining quantum yields of a surface in a cesiated plasma environment is being assembled. Some preliminary test results of the apparatus utilizing oxide cathodes are reported.

  8. Effect of atmospheric oxidative plasma treatments on polypropylenic fibers surface: Characterization and reaction mechanisms

    NASA Astrophysics Data System (ADS)

    Nisticò, Roberto; Magnacca, Giuliana; Faga, Maria Giulia; Gautier, Giovanna; D'Angelo, Domenico; Ciancio, Emanuele; Lamberti, Roberta; Martorana, Selanna

    2013-08-01

    Atmospheric pressure plasma-dielectric barrier discharge (APP-DBD, open chamber configuration) was used to functionalize polypropylene (PP) fibers surface in order to generate oxidized-reactive groups such as hydroperoxides, alcohols and carbonyl species (i.e. ketones and others). Such a species increased the surface polarity, without causing material degradation. Three different types of plasma mixture (He, He/O2, He/O2/H2O) under three different values of applied power (750, 1050, 1400 W) were investigated. The formed plasma species (O2+, O single atom and OH radical) and their distribution were monitored via optical emission spectrometry (OES) measurements, and the plasma effects on PP surface species formation were followed by X-ray photoemission spectroscopy (XPS). Results allowed to better understand the reaction pathways between plasma phase and PP fibers. In fact, two reaction mechanisms were proposed, the first one concerning the plasma phase reactions and the second one involving material surface modifications.

  9. Surface morphology of RF plasma immersion H+ ion implanted and oxidized Si(100) surface

    NASA Astrophysics Data System (ADS)

    Anastasescu, M.; Stoica, M.; Gartner, M.; Bakalova, S.; Szekeres, A.; Alexandrova, S.

    2014-05-01

    The surface morphology of p-Si(100) wafers after RF plasma immersion (PII) H+ ion implantation into a shallow Si surface layer and after subsequent thermal oxidation was studied by atomic-force microscopic (AFM) imaging. After PII implantation of hydrogen ions with an energy of 2 keV and fluences ranging from 1013 cm-2 to 1015 cm-2 the Si wafers were oxidized in dry O2 at temperatures ranging from 700 °C to 800 °C. From the analysis of the AFM images, the surface amplitude parameters were evaluated and considered in terms of the technological conditions. The amplitude parameters showed a clear dependence on the H+ dose and the oxidation temperature, with the tendency of increasing with the increase of both the H+ ion fluence and the oxidation temperature. The implantation causes surface roughening, changing the RMS roughness value from 0.15 nm (typical for a polished Si(100) surface) to the highest value 0.6 nm for the H+ fluence of 1015 ions/cm2. Oxidation of the H+ implanted Si region, as the oxide is growing inward into Si, levels away the pits created by implants and results in a smoother surface, although keeping the RMS values larger than 0.2 nm.

  10. Electromagnetic wave band structure due to surface plasmon resonances in a complex plasma

    NASA Astrophysics Data System (ADS)

    Vladimirov, S. V.; Ishihara, O.

    2016-07-01

    The dielectric properties of complex plasma containing either metal or dielectric spherical inclusions (macroparticles, dust) are investigated. We focus on surface plasmon resonances on the macroparticle surfaces and their effect on electromagnetic wave propagation. It is demonstrated that the presence of surface plasmon oscillations can significantly modify plasma electromagnetic properties by resonances and cutoffs in the effective permittivity. This leads to related branches of electromagnetic waves and to the wave band gaps. The conditions necessary to observe the band-gap structure in laboratory dusty plasma and/or space (cosmic) dusty plasmas are discussed.

  11. Engineering of surfaces for energy-related applications

    NASA Astrophysics Data System (ADS)

    Umeda, Grant Asano

    Finding solutions to today's energy challenges will be spearheaded by the development of novel materials systems. This dissertation examines the engineering of surfaces for both energy collection and energy storage. Energy collection research, such as the development of more efficient photovoltaic devices, has received much attention in recent literature, however, achieving inexpensive efficiency improvements in other parts of the photovoltaic system has not been well documented. The first part of this dissertation examines the possibility of utilizing a sol-gel approach to fabricate a single-layer abrasion-resistant antireflective coating for cover glass for solar cell arrays. By controlling the porosity of the film to reduce reflection from the substrate, and by controlling the chemistry of the sol-gel formation, we have achieved a film that is both durable and exhibits excellent antireflection properties. The second part of this dissertation examines a novel approach to the protection of lithium metal for use in secondary batteries. Current lithium-ion technologies utilize carbon anodes which have a low energy density compared to lithium metal. However, the interaction between lithium metal and commercially available non-aqueous electrolytes produces an inhomogeneous layer on the surface of the lithium which results in poor cycle life. A novel coating is presented which uses sol-gel precursors to stabilize the surface of lithium metal and results in a film that protects a lithium metal surface for over 100 cycles of stripping and plating.

  12. Biomolecular Surface Engineering of Pancreatic Islets with Thrombomodulin

    PubMed Central

    Wilson, John T.; Haller, Carolyn A.; Qu, Zheng; Cui, Wanxing; Urlam, Murali K.; Chaikof, Elliot L.

    2010-01-01

    Islet transplantation has emerged as a promising treatment for Type 1 diabetes, but its clinical impact remains limited by early islet destruction mediated by prothrombotic and innate inflammatory responses elicited upon transplantation. Thrombomodulin (TM) acts as an important regulator of thrombosis and inflammation through its capacity to channel the catalytic activity of thrombin towards generation of activated protein C (APC), a potent anti-coagulant and anti-inflammatory agent. We describe herein a novel biomolecular strategy for re-engineering the surface of pancreatic islets with TM. A biosynthetic approach was employed to generate recombinant human TM (rTM) bearing a C-terminal azide group, which facilitated site-specific biotinylation of rTM through Staudinger ligation. Murine pancreatic islets were covalently biotinylated through targeting of cell surface amines and aldehydes, and both islet viability and the surface density of streptavidin were maximized through optimization of biotinylation conditions. rTM was immobilized on islet surfaces through streptavidin-biotin interactions, resulting in a nearly three-fold increase in the catalytic capacity of islets to generate APC. PMID:20102751

  13. Validation of plasma shape reconstruction by Cauchy condition surface method in KSTAR

    SciTech Connect

    Miyata, Y.; Suzuki, T.; Ide, S.; Hahn, S. H.; Chung, J.; Bak, J. G.; Ko, W. H.

    2014-03-15

    Cauchy Condition Surface (CCS) method is a numerical approach to reconstruct the plasma boundary and calculate the quantities related to plasma shape using the magnetic diagnostics in real time. It has been applied to the KSTAR plasma in order to establish the plasma shape reconstruction with the high elongation of plasma shape and the large effect of eddy currents flowing in the tokamak structures for the first time. For applying the CCS calculation to the KSTAR plasma, the effects by the eddy currents and the ferromagnetic materials on the plasma shape reconstruction are studied. The CCS calculation includes the effect of eddy currents and excludes the magnetic diagnostics, which is expected to be influenced largely by ferromagnetic materials. Calculations have been performed to validate the plasma shape reconstruction in 2012 KSTAR experimental campaign. Comparison between the CCS calculation and non-magnetic measurements revealed that the CCS calculation can reconstruct the accurate plasma shape even with a small I{sub P}.

  14. Pulsed microwave-driven argon plasma jet with distinctive plume patterns resonantly excited by surface plasmon polaritons

    NASA Astrophysics Data System (ADS)

    Chen, Zhao-Quan; Yin, Zhi-Xiang; Xia, Guang-Qing; Hong, Ling-Li; Hu, Ye-Lin; Liu, Ming-Hai; Hu, Xi-Wei; A. Kudryavtsev, A.

    2015-02-01

    Atmospheric lower-power pulsed microwave argon cold plasma jets are obtained by using coaxial transmission line resonators in ambient air. The plasma jet plumes are generated at the end of a metal wire placed in the middle of the dielectric tubes. The electromagnetic model analyses and simulation results suggest that the discharges are excited resonantly by the enhanced electric field of surface plasmon polaritons. Moreover, for conquering the defect of atmospheric argon filamentation discharges excited by 2.45-GHz of continued microwave, the distinctive patterns of the plasma jet plumes can be maintained by applying different gas flow rates of argon gas, frequencies of pulsed modulator, duty cycles of pulsed microwave, peak values of input microwave power, and even by using different materials of dielectric tubes. In addition, the emission spectrum, the plume temperature, and other plasma parameters are measured, which shows that the proposed pulsed microwave plasma jets can be adjusted for plasma biomedical applications. Project supported by the National Natural Science Foundation of China (Grant Nos. 11105002 and 61170172), the Natural Science Foundation of Anhui Province, China (Grant Nos. 1408085QA16 and 1408085ME101), the China Postdoctoral Science Foundation (Grant No. 2014M551788), and the Open-end Fund of State Key Laboratory of Advanced Electromagnetic Engineering and Technology (HUST), China (Grant No. GZ1301).

  15. Plasma Science and Applications at the Intel International Science and Engineering Fair

    NASA Astrophysics Data System (ADS)

    Berry, Lee

    2005-10-01

    The Coalition for Plasma Science (CPS) has established a plasma prize at the Intel International Science and Engineering Fair (ISEF). This year's prize was awarded for projects in simulated ball lightning and plasma thrusters. The CPS is a broadly-based group of institutions and individuals whose goal is to increase the understanding of plasmas for non-technical audiences. In addition to the ISEF plasma award, CPS activities include maintaining a website, http://www.plasmacoalition.org; developing educational literature; organizing educational luncheon presentations for Members of Congress and their staffs; and responding to questions about plasmas that are received by the CPS e-mail or toll-free number. The success of these activities depend on the voluntary labor of CPS members and associates. These volunteers include the ISEF judges, whom the APS/DPP and the IEEE/PSAC helped identify. Please send an e-mail to the CPS at CPS@plasmacoalition.org for information if you would like to become involved in spreading the good word about plasmas.

  16. Influence of different surface modification treatments on silk biotextiles for tissue engineering applications.

    PubMed

    Ribeiro, Viviana P; Almeida, Lília R; Martins, Ana R; Pashkuleva, Iva; Marques, Alexandra P; Ribeiro, Ana S; Silva, Carla J; Bonifácio, Graça; Sousa, Rui A; Reis, Rui L; Oliveira, Ana L

    2016-04-01

    Biotextile structures from silk fibroin have demonstrated to be particularly interesting for tissue engineering (TE) applications due to their high mechanical strength, interconnectivity, porosity, and ability to degrade under physiological conditions. In this work, we described several surface treatments of knitted silk fibroin (SF) scaffolds, namely sodium hydroxide (NaOH) solution, ultraviolet radiation exposure in an ozone atmosphere (UV/O3) and oxygen (O2) plasma treatment followed by acrylic acid (AAc), vinyl phosphonic acid (VPA), and vinyl sulfonic acid (VSA) immersion. The effect of these treatments on the mechanical properties of the textile constructs was evaluated by tensile tests in dry and hydrated states. Surface properties such as morphology, topography, wettability and elemental composition were also affected by the applied treatments. The in vitro biological behavior of L929 fibroblasts revealed that cells were able to adhere and spread both on the untreated and surface-modified textile constructs. The applied treatments had different effects on the scaffolds' surface properties, confirming that these modifications can be considered as useful techniques to modulate the surface of biomaterials according to the targeted application.

  17. Atmospheric-pressure plasma activation and surface characterization on polyethylene membrane separator

    NASA Astrophysics Data System (ADS)

    Tseng, Yu-Chien; Li, Hsiao-Ling; Huang, Chun

    2017-01-01

    The surface hydrophilic activation of a polyethylene membrane separator was achieved using an atmospheric-pressure plasma jet. The surface of the atmospheric-pressure-plasma-treated membrane separator was found to be highly hydrophilic realized by adjusting the plasma power input. The variations in membrane separator chemical structure were confirmed by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. Chemical analysis showed newly formed carbonyl-containing groups and high surface concentrations of oxygen-containing species on the atmospheric-pressure-plasma-treated polymeric separator surface. It also showed that surface hydrophilicity primarily increased from the polar component after atmospheric-pressure plasma treatment. The surface and pore structures of the polyethylene membrane separator were examined by scanning electron microscopy, revealing a slight alteration in the pore structure. As a result of the incorporation of polar functionalities by atmospheric-pressure plasma activation, the electrolyte uptake and electrochemical impedance of the atmospheric-pressure-plasma-treated membrane separator improved. The investigational results show that the separator surface can be controlled by atmospheric-pressure plasma surface treatment to tailor the hydrophilicity and enhance the electrochemical performance of lithium ion batteries.

  18. Surface waves and space charge layers in a spatially inhomogeneous plasma

    SciTech Connect

    Kuzelev, M. V.; Romanov, R. V.; Rukhadze, A. A.; Khundzhua, N. G.

    2007-12-15

    A theory of surface waves in a layer of a spatially inhomogeneous cold electron plasma is presented. Four types of surface waves are revealed, and the conditions under which they can exist are determined. Complex frequency spectra are obtained, and the mechanisms for wave damping by plasma inhomogeneity are discussed.

  19. Study of plasma formation in CW CO2 laser beam-metal surface interaction

    NASA Astrophysics Data System (ADS)

    Azharonok, V. V.; Vasilchenko, Zh V.; Golubev, Vladimir S.; Gresev, A. N.; Zabelin, Alexandre M.; Chubrik, N. I.; Shimanovich, V. D.

    1994-04-01

    An interaction of the cw CO2 laser beam and a moving metal surface has been studied. The pulsed and thermodynamical parameters of the surface plasma were investigated by optical and spectroscopical methods. The subsonic radiation wave propagation in the erosion plasma torch has been studied.

  20. Enhancement of Biocompatibility on Bioactive Titanium Surface by Low-Temperature Plasma Treatment

    NASA Astrophysics Data System (ADS)

    Lin, Chia-Cheng; Cheng, Hsin-Chung; Huang, Chiung-Fang; Lin, Che-Tong; Lee, Sheng-Yang; Chen, Chin-Sung; Ou, Keng-Liang

    2005-12-01

    The surface of implantable biomaterials directly contacts the host tissue and is critical in determining biocompatibility. To improve implant integration, interfacial reactions must be controlled to minimize nonspecific adsorption of proteins, and tissue-healing phenomena can be controlled. The purpose of this study was to develop a new method of functionalizing titanium surfaces by plasma treatment. The covalent immobilization of bioactive organic molecules and the bioactivities in vitro were assessed by transmission electron microscopy (TEM), atomic force spectroscopy (AFM), X-ray photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), and 3-(4,5-dimethylthiazole-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay as indices of cellular cytotoxicity. Argon plasma removed all of the adsorbed contaminants and impurities. Plasma-cleaned titanium surfaces showed better bioactive performances than untreated titanium surfaces. The analytical results reveal that plasma-cleaned titanium surfaces provide a clean and reproducible starting condition for further plasma treatments to create well-controlled surface layers. Allylamine was ionized by plasma treatment, and acted as a medium to link albumin. Cells demonstrated a good spread, and a wide attachment was attained on the Albu-Ti plate. Cell attachment and growth were shown to be influenced by the surface properties. The plasma treatment process plays an important role in facilitating tissue healing. This process not only provides a clean titanium surface, but also leads to surface amination on plasma-treated titanium surfaces. Surface cleaning by ion bombardment and surface modification by plasma polymerization are believed to remove contamination on titanium surfaces and thus promote tissue healing.

  1. Wear Protection of AJ62 Mg Engine Blocks using Plasma Electrolytic Oxidation Process

    NASA Astrophysics Data System (ADS)

    Zhang, Peng

    2011-12-01

    In order to reduce the fuel consumption and pollution, automotive companies are developing magnesium-intensive components. However, due to the low wear resistance of the magnesium (Mg) alloys, Mg cylinder bores are vulnerable to the sliding wear attack. In this thesis, two approaches were used to protect the cylinder bores, made of a new developed Mg engine alloy AJ62 (MgA16Mn0.34Sr2). The first one was to use a Plasma Electrolytic Oxidation (PEO) process to produce oxide coatings on the Mg bores. The wear properties of the PEO coatings were evaluated by sliding wear tests under the boundary lubrication condition at the room and elevated temperatures. It was found that due to the substrate softening and the vaporization loss of the lubricant, the tribological properties of the PEO coatings were deteriorated at the elevated temperature. In order to optimize the PEO process, a statistical method (Response surface method) was used to analyze the effects of the 4 main PEO process parameters with 2 levels for each and their interactions on the tribological properties of the PEO coatings at the room and elevated temperatures, individually. A cylinder liner made of an economical metal-matrix composite (MMC) was another approach to improve the wear resistance of the Mg cylinder bore. In this thesis, an A1383/SiO2 MMC was designed to replace the expensive Alusil alloy used in the BMW Mg/Al composite engine to build the cylinder liner. To further increase the wear resistance of the MMC, PEO process was also used to form an oxide coating on the MMC. The effects of the SiO 2 content and coating thickness on the tribological properties of the MMC were studied. To evaluate the wear properties of the optimal PEO coated Mg coupons and the MMC with the oxide coatings, Alusil and cast iron, currently used on the cylinder bores of the commercial aluminum engines, were used as reference materials. The optimal PEO coated Mg coupons and the oxidized MMC showed their advantages over the

  2. Surface modification of fluorosilicone acrylate RGP contact lens via low-temperature argon plasma

    NASA Astrophysics Data System (ADS)

    Yin, Shiheng; Wang, Yingjun; Ren, Li; Zhao, Lianna; Kuang, Tongchun; Chen, Hao; Qu, Jia

    2008-11-01

    A fluorosilicone acrylate rigid gas permeable (RGP) contact lens was modified via argon plasma to improve surface hydrophilicity and resistance to protein deposition. The influence of plasma treatment on surface chemical structure, hydrophilicity and morphology of RGP lens was investigated by X-ray photoelectron spectrometer (XPS), contact angle measurements and scanning electron microscope (SEM), respectively. The contact angle results showed that the hydrophilicity of the contact lens was improved after plasma treatment. XPS results indicated that the incorporation of oxygen-containing groups on surface and the transformation of silicone into hydrophilic silicate after plasma treatment are the main reasons for the surface hydrophilicity improvement. SEM results showed that argon plasma with higher power could lead to surface etching.

  3. Effect of plasma grid bias on extracted currents in the RF driven surface-plasma negative ion source

    SciTech Connect

    Belchenko, Yu. Ivanov, A.; Sanin, A.; Sotnikov, O.; Shikhovtsev, I.

    2016-02-15

    Extraction of negative ions from the large inductively driven surface-plasma negative ion source was studied. The dependencies of the extracted currents vs plasma grid (PG) bias potential were measured for two modifications of radio-frequency driver with and without Faraday screen, for different hydrogen feeds and for different levels of cesium conditioning. The maximal PG current was independent of driver modification and it was lower in the case of inhibited cesium. The maximal extracted negative ion current depends on the potential difference between the near-PG plasma and the PG bias potentials, while the absolute value of plasma potential in the driver and in the PG area is less important for the negative ion production. The last conclusion confirms the main mechanism of negative ion production through the surface conversion of fast atoms.

  4. Permanent hydrophilization of outer and inner surfaces of polytetrafluoroethylene tubes using ambient air plasma generated by surface dielectric barrier discharges

    SciTech Connect

    Pavliňák, D.; Galmiz, O.; Zemánek, M.; Brablec, A.; Čech, J.; Černák, M.

    2014-10-13

    We present an atmospheric pressure ambient air plasma technique developed for technically simple treatment of inner and/or outer surfaces of plastic tubes and other hollow dielectric bodies. It is based on surface dielectric barrier discharge generating visually diffuse plasma layers along the treated dielectric surfaces using water-solution electrodes. The observed visual uniformity and measured plasma rotational and vibrational temperatures of 333 K and 2350 K indicate that the discharge can be readily applied to material surface treatment without significant thermal effect. This is exemplified by the obtained permanent surface hydrophilization of polytetrafluoroethylene tubes related to the replacement of a high fraction (more than 80%) of the surface fluorine determined by X-ray photoelectron spectroscopy. A tentative explanation of the discharge mechanism based on high-speed camera observations and the discharge current and voltage of measurements is outlined.

  5. Engineering design constraints of the lunar surface environment

    NASA Technical Reports Server (NTRS)

    Morrison, D. A.

    1992-01-01

    Living and working on the lunar surface will be difficult. Design of habitats, machines, tools, and operational scenarios in order to allow maximum flexibility in human activity will require paying attention to certain constraints imposed by conditions at the surface and the characteristics of lunar material. Primary design drivers for habitat, crew health and safety, and crew equipment are: ionizing radiation, the meteoroid flux, and the thermal environment. Secondary constraints for engineering derive from: the physical and chemical properties of lunar surface materials, rock distributions and regolith thicknesses, topography, electromagnetic properties, and seismicity. Protection from ionizing radiation is essential for crew health and safety. The total dose acquired by a crew member will be the sum of the dose acquired during EVA time (when shielding will be least) plus the dose acquired during time spent in the habitat (when shielding will be maximum). Minimizing the dose acquired in the habitat extends the time allowable for EVA's before a dose limit is reached. Habitat shielding is enabling, and higher precision in predicting secondary fluxes produced in shielding material would be desirable. Means for minimizing dose during a solar flare event while on extended EVA will be essential. Early warning of the onset of flare activity (at least a half-hour is feasible) will dictate the time available to take mitigating steps. Warning capability affects design of rovers (or rover tools) and site layout. Uncertainty in solar flare timing is a design constraint that points to the need for quickly accessible or constructible safe havens.

  6. Modification of Fluorinated Al2O3 Surface by Irradiating H2 and O2 Plasmas

    NASA Astrophysics Data System (ADS)

    Miwa, Kazuhiro; Usami, Kenji; Takada, Noriharu; Sasaki, Koichi

    2009-12-01

    We irradiated H2 and O2 plasmas onto fluorinated Al2O3, which was prepared by exposing a virgin Al2O3 sample to an SF6/O2 plasma. The effects of the H2 plasma irradiation were the reduction of the AlOxFy (x + y = 1.5) and AlFx (x < 3) bonding components and the realization of smooth sample surface. It was observed that the irradiation of the H2 plasma induced Al-OH bonding. The Al-OH bonding was removed by the sequential irradiation of the O2 plasma after the H2 plasma irradiation. The O2 plasma irradiation also resulted in peroxidation and an increase in surface roughness.

  7. Plasma assisted ignition with nanosecond surface dielectric barrier discharge. Two modes of nanosecond surface discharge

    NASA Astrophysics Data System (ADS)

    Shcherbanev, Sergey; Popov, Nikolay; Starikovskaia, Svetlana; LPP Team; LIA France-Russia Collaboration

    2016-09-01

    Nanosecond surface dielectric barrier discharge (nSDBD) is an efficient tool for a multi-point plasma-assisted ignition of combustible mixtures at elevated pressures. In combustible mixtures, nSDBD initiates numerous combustion waves propagating from the electrode. This work presents a comparative experimental study of the surface dielectric barrier discharge initiated by high voltage pulses (U =+/-(20-60) kV) of different polarities in air at elevated pressures (P =1 -12 bar). Discharge morphology, deposited energy, and spectroscopy of the discharges are analyzed. Differences between the discharges of the different polarity, as well as the changes in the discharge morphology with changing of a gas mixture composition, are discussed. The initiation of combustion with nSDBD was studied experimentally at high initial pressures up to 6 bar on the example of lean H2/Air. The ignition is initiated with two different discharge modes: streamer and filamentary. The influence of the discharge structure and energy deposition on the ignition is demonstrated. Three regimes of multi-point ignition were observed: ignition with a few kernels, quasi-uniform ignition along the edge of high voltage electrodes and ignition along the plasma channels.

  8. Note: A single-chamber tool for plasma activation and surface functionalization in microfabrication

    PubMed Central

    Bowman, Adam J.; Scherrer, Joseph R.; Reiserer, Ronald S.

    2015-01-01

    We present a simple apparatus for improved surface modification of polydimethylsiloxane (PDMS) microfluidic devices. A single treatment chamber for plasma activation and chemical/physical vapor deposition steps minimizes the time-dependent degradation of surface activation that is inherent in multi-chamber techniques. Contamination and deposition irregularities are also minimized by conducting plasma activation and treatment phases in the same vacuum environment. An inductively coupled plasma driver allows for interchangeable treatment chambers. Atomic force microscopy confirms that silane deposition on PDMS gives much better surface quality than standard deposition methods, which yield a higher local roughness and pronounced irregularities in the surface. PMID:26133881

  9. Note: A single-chamber tool for plasma activation and surface functionalization in microfabrication

    SciTech Connect

    Bowman, Adam J.; Scherrer, Joseph R.; Reiserer, Ronald S.

    2015-06-15

    We present a simple apparatus for improved surface modification of polydimethylsiloxane (PDMS) microfluidic devices. A single treatment chamber for plasma activation and chemical/physical vapor deposition steps minimizes the time-dependent degradation of surface activation that is inherent in multi-chamber techniques. Contamination and deposition irregularities are also minimized by conducting plasma activation and treatment phases in the same vacuum environment. An inductively coupled plasma driver allows for interchangeable treatment chambers. Atomic force microscopy confirms that silane deposition on PDMS gives much better surface quality than standard deposition methods, which yield a higher local roughness and pronounced irregularities in the surface.

  10. Surface Engineering of Graphene-Based Nanomaterials for Biomedical Applications

    PubMed Central

    2015-01-01

    Graphene-based nanomaterials have attracted tremendous interest over the past decade due to their unique electronic, optical, mechanical, and chemical properties. However, the biomedical applications of these intriguing nanomaterials are still limited due to their suboptimal solubility/biocompatibility, potential toxicity, and difficulties in achieving active tumor targeting, just to name a few. In this Topical Review, we will discuss in detail the important role of surface engineering (i.e., bioconjugation) in improving the in vitro/in vivo stability and enriching the functionality of graphene-based nanomaterials, which can enable single/multimodality imaging (e.g., optical imaging, positron emission tomography, magnetic resonance imaging) and therapy (e.g., photothermal therapy, photodynamic therapy, and drug/gene delivery) of cancer. Current challenges and future research directions are also discussed and we believe that graphene-based nanomaterials are attractive nanoplatforms for a broad array of future biomedical applications. PMID:25117569

  11. Surface engineering of graphene-based nanomaterials for biomedical applications.

    PubMed

    Shi, Sixiang; Chen, Feng; Ehlerding, Emily B; Cai, Weibo

    2014-09-17

    Graphene-based nanomaterials have attracted tremendous interest over the past decade due to their unique electronic, optical, mechanical, and chemical properties. However, the biomedical applications of these intriguing nanomaterials are still limited due to their suboptimal solubility/biocompatibility, potential toxicity, and difficulties in achieving active tumor targeting, just to name a few. In this Topical Review, we will discuss in detail the important role of surface engineering (i.e., bioconjugation) in improving the in vitro/in vivo stability and enriching the functionality of graphene-based nanomaterials, which can enable single/multimodality imaging (e.g., optical imaging, positron emission tomography, magnetic resonance imaging) and therapy (e.g., photothermal therapy, photodynamic therapy, and drug/gene delivery) of cancer. Current challenges and future research directions are also discussed and we believe that graphene-based nanomaterials are attractive nanoplatforms for a broad array of future biomedical applications.

  12. Plasma-assisted physical vapor deposition surface treatments for tribological control

    NASA Technical Reports Server (NTRS)

    Spalvins, Talivaldis

    1990-01-01

    In any mechanical or engineering system where contacting surfaces are in relative motion, adhesion, wear, and friction affect reliability and performance. With the advancement of space age transportation systems, the tribological requirements have dramatically increased. This is due to the optimized design, precision tolerance requirements, and high reliability expected for solid lubricating films in order to withstand hostile operating conditions (vacuum, high-low temperatures, high loads, and space radiation). For these problem areas the ion-assisted deposition/modification processes (plasma-based and ion beam techniques) offer the greatest potential for the synthesis of thin films and the tailoring of adherence and chemical and structural properties for optimized tribological performance. The present practices and new approaches of applying soft solid lubricant and hard wear resistant films to engineering substrates are reviewed. The ion bombardment treatments have increased film adherence, lowered friction coefficients, and enhanced wear life of the solid lubricating films such as the dichalcogenides (MoS2) and the soft metals (Au, Ag, Pb). Currently, sputtering is the preferred method of applying MoS2 films; and ion plating, the soft metallic films. Ultralow friction coefficients (less than 0.01) were achieved with sputtered MoS2. Further, new diamond-like carbon and BN lubricating films are being developed by using the ion assisted deposition techniques.

  13. Plasma properties of a new-type surface wave-sustained plasma source under the conditions of depositing DLC films

    NASA Astrophysics Data System (ADS)

    Xu, Junqi; Kousaka, Hiroyuki; Umehara, Noritsugu; Diao, Dongfeng

    2006-01-01

    Surface wave-sustained plasma (SWP) is one of the low-pressure, high- density plasma. Applying this technique, diamond-like carbon (DLC) films with excellent characteristics can be prepared by physical vapor deposition (PVD) method. However, the films' application is restricted in some degree, because it is difficult to control the film properties. In this paper, SWP was excited along a conductive rod at a frequency of 2.45 GHz without magnetic fields around the chamber wall. The fundamental theories of plasma diagnostic were presented and plasma properties were studied with a Langmuir probe under the conditions of depositing DLC films by PVD method with a graphite target. Plasma density, electron temperature, plasma potential and target current were measured at difference technique parameters such as gas pressure, microwave power, and so on. As a result, it was proved that plasma properties are greatly affected by microwave power, target voltage and argon gas pressure in chamber. The gas mass flow rate had almost no effect on plasma characters. At the same time, the results indicated that electron density is up to 10 11-10 12cm -3 even at the low pressure of 1 Pa.

  14. Instabilities in uranium plasma and the gas-core nuclear rocket engine

    NASA Technical Reports Server (NTRS)

    Tidman, D. A.

    1972-01-01

    The nonlinear evolution of unstable sound waves in a uranium plasma has been calculated using a multiple time-scale asymptotic expansion scheme. The fluid equations used include the fission power density, radiation diffusion, and the effects of the changing degree of ionization of the uranium atoms. The nonlinear growth of unstable waves is shown to be limited by mode coupling to shorter wavelength waves which are damped by radiation diffusion. This mechanism limits the wave pressure fluctuations to values of order delta P/P approximates 0.00001 in the plasma of a typical gas-core nuclear rocket engine. The instability is thus not expected to present a control problem for this engine.

  15. [Improvement of PVC bio-carrier surface property by remote plasma].

    PubMed

    Li, Ru; Chen, Jie-Rong; Chen, Jun; Yao, Xin

    2006-01-01

    The effects of various remote plasma, such as Ar, He, O2 and N2 on PVC bio-carrier surface modification were studied. The surface properties were characterized by the contact angle measurement and X-ray photoelectron spectroscopy (XPS). The role of all kinds of active species such as electrons, ions and free radicals involved in plasma surface modification were evaluated. Results show that the remote plasma treatments modify the PVC surface in both wettability and composition, the (O + N)/C of PVC surface increases from 7% to 22%, and the water contact angle decreases from 97 degrees to 15 degrees. The optimal results was achieved when plasma treatment parameters were set, that is treatment time 3 min, Ar flux at 20 cm3/s, power at 60W, sample position of 40 cm. The results show that the modified PVC Bio-carrier adhesion rate and capacity on the modified surface are greatly increased.

  16. Multilevel surface engineering of nanostructured TiO2 on carbon-fiber-reinforced polyetheretherketone.

    PubMed

    Lu, Tao; Liu, Xuanyong; Qian, Shi; Cao, Huiliang; Qiao, Yuqin; Mei, Yongfeng; Chu, Paul K; Ding, Chuanxian

    2014-07-01

    As an implantable material, carbon-fiber-reinforced polyetheretherketone (CFRPEEK) possesses an adjustable elastic modulus similar to that of cortical bone and is a prime candidate to replace metallic surgical implants. However, the bioinertness and poor osteogenic properties of CFRPEEK limit its clinical application as orthopedic implants. In this work, titanium ions are introduced energetically into CFRPEEK by plasma immersion ion implantation (PIII). Scanning electron microscopy (SEM) and X-ray photoelectron spectroscopy (XPS) reveal the formation of nanopores with the side wall and bottom embedded with ∼20 nm TiO2 nanoparticles on the CFRPEEK surface. Nanoindentation measurements confirm the stability and improved elastic resistance of the structured surfaces. In vitro cell adhesion, viability assay, and real-time PCR analyses disclose enhanced adhesion, proliferation, and osteo-differentiation of rat bone mesenchymal stem cells (bMSCs). The multilevel structures on CFRPEEK also exhibit partial antibacterial activity to Staphylococcus aureus and Escherichia coli. Our results indicate that a surface with multifunctional biological properties can be produced by multilevel surface engineering and application of CFRPEEK to orthopedic and dental implants can be broadened and expedited based on this scheme.

  17. Negative plasma potential relative to electron-emitting surfaces.

    PubMed

    Campanell, M D

    2013-09-01

    Most works on plasma-wall interaction predict that with strong electron emission, a nonmonotonic "space-charge-limited" (SCL) sheath forms where the plasma potential is positive relative to the wall. We show that a fundamentally different sheath structure is possible where the potential monotonically increases toward a positively charged wall that is shielded by a single layer of negative charge. No ion-accelerating presheath exists in the plasma and the ion wall flux is zero. An analytical solution of the "inverse sheath" regime is demonstrated for a general plasma-wall system where the plasma electrons and emitted electrons are Maxwellian with different temperatures. Implications of the inverse sheath effect are that (a) the plasma potential is negative, (b) ion sputtering vanishes, (c) no charge is lost at the wall, and (d) the electron energy flux is thermal. To test empirically what type of sheath structure forms under strong emission, a full plasma bounded by strongly emitting walls is simulated. It is found that inverse sheaths form at the walls and ions are confined in the plasma. This result differs from past particle-in-cell simulation studies of emission which contain an artificial "source sheath" that accelerates ions to the wall, leading to a SCL sheath at high emission intensity.

  18. Dusty Plasma Technology of DCM with Nanostructure Surface Layer Production

    SciTech Connect

    Gavrikov, A. V.; Ivanov, A. S.; Petrov, O. F.; Shulga, Yu. M.; Starostin, A. N.; Fortov, V. E.

    2008-09-07

    The technique of disperse composite material (DCM) production was developed. The technique based on using special dusty plasma trap in RF plasma, in which fine particles levitate and are exposed by the atomic beam. The two types of covering were obtained: ''cauliflower'' or smooth, depending on process condition.

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

    SciTech Connect

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

    2004-09-21

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

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

    DOEpatents

    Carr, Jeffrey W.

    2009-09-22

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

  1. Apparatus for coating a surface with a metal utilizing a plasma source

    DOEpatents

    Brown, I.G.; MacGill, R.A.; Galvin, J.E.

    1991-05-07

    An apparatus and method are disclosed for coating or layering a surface with a metal utilizing a metal vapor vacuum arc plasma source. The apparatus includes a trigger mechanism for actuating the metal vacuum vapor arc plasma source in a pulsed mode at a predetermined rate. The surface or substrate to be coated or layered is supported in position with the plasma source in a vacuum chamber. The surface is electrically biased for a selected period of time during the pulsed mode of operation of the plasma source. Both the pulsing of the metal vapor vacuum arc plasma source and the electrical biasing of the surface are synchronized for selected periods of time. 10 figures.

  2. Bullet-to-streamer transition on the liquid surface of a plasma jet in atmospheric pressure

    NASA Astrophysics Data System (ADS)

    Yoon, S.-Y.; Kim, G.-H.; Kim, S.-J.; Bae, B.; Kim, N.-K.; Lee, H.; Bae, N.; Ryu, S.; Yoo, S. J.; Kim, S. B.

    2017-01-01

    This study investigated the transition of the plasma shape from a ring-shaped bullet to a pin-like streamer adjacent to the electrolyte surface in a kHz-driven helium atmospheric pressure plasma jet. The transition was observed by synchronized fast images, plasma propagation speed, time-resolved emission profile of Hβ, and spatially and temporally resolved helium metastable density. The transition height increased when electrolyte evaporation was enhanced. The plasma continued to discharge on the electrolyte surface even in the absence of metastable species, i.e., the discharge mechanism changed from Penning ionization between helium metastable and ambient nitrogen to electron collision on evaporated water.

  3. CTR plasma engineering studies. Annual progress report, 1 October 1979--30 September 1080

    SciTech Connect

    Miley, G.H.

    1980-01-01

    FY 1980 CTR Plasma Engineering Studies performed at the University of Illinois are reported. Current studies concentrated on four major areas including (i) field-reversed mirror (FRM) and related compact tori, (ii) dynamic behavior of the reversed-field pinch (RFP) including transport and stability and start-up, (iii) plasma buildup in small mirrors by including finite, ion orbit effects as well as the drift cyclotron loss-cone velocity-space diffusion, and (iv) high-energy fusion product transport in non-circular and high-..beta.. tokamaks, alpha ash buildup and possible control in tokamaks. Various computer packages have been produced for FRM, FROP, RFP, small compact tori and non-circular tokamaks. Basic models and the code packages developed and tested with available experiments are of vital information that can be used in conceptual reactor studies for the scaling and prediction of plasma behavior in near-term reactors.

  4. Creation of fluorocarbon barriers on surfaces of starch-based products through cold plasma treatment

    NASA Astrophysics Data System (ADS)

    Han, Yousoo

    Two kinds of starch foam trays (starch and aspen-starch foam trays) were produced using a lab model baking machine. Surfaces of the trays were treated with CF4 and SF6 plasma to create fluorine-rich layers on the surfaces, which might show strong water resistance. The plasma parameters, such like RF power, gas pressure and reaction time, were varied to evaluate the effects of each parameter on fluorination of surfaces. The atomic concentrations of fluorine, oxygen and carbon on samples' surfaces were earned from ESCA (electron spectroscopy for chemical analysis) and contact angles of sample surfaces were measured for hydrophobicity. For water resistance of plasma treated surfaces, liquid water uptake and water vapor uptake test were performed. Also, equilibrium moisture contents of unmodified and plasma treated samples were measured to evaluate biodegradability of plasma treated samples. Fluorine-rich barriers were created on sample surfaces treated with CF 4 and SF6 plasma. The fluorine atomic concentrations of treated sample surfaces were ranged from 34.4% to 64.4% (CF4 treatment) and 43.6% to 57.9% (SF6 treatment). It was found at both plasma gases that plasma parameters affected total fluorine concentration and carbon-peak shapes in ESCA surveys, which imply different distributions of mono- or multi-fluoro carbon's contents. In various reaction times, it was found that total fluorine contents were decreased after a critical point as the reaction time was prolonged, which may imply that a dominant mechanism has been changed from deposition or functionalization to etching. Oxygen atomic concentration was decreased at sample surfaces treated by both plasmas. In the case of SF6 plasma, it was proved that the removal of oxygen surely occurred because there was no addition of sulfur species. Plasma treated sample surfaces had high contact angles with distilled water up to 150° and the high values of angles have been kept constant up to for 15 minutes. Fluorine

  5. An overview of the VASIMR engine: High power space propulsion with RF plasma generation and heating

    NASA Astrophysics Data System (ADS)

    Díaz, F. R. Chang

    2001-10-01

    The Variable Specific Impulse Magnetoplasma Rocket (VASIMR) is a high power, radio frequency-driven magnetoplasma rocket, capable of exhaust modulation at constant power. While the plasma is produced by a helicon discharge, the bulk of the energy is added in a separate downstream stage by ion cyclotron resonance heating (ICRH). Axial momentum is obtained by the adiabatic expansion of the plasma in a magnetic nozzle. Exhaust variation in the VASIMR is primarily achieved by the selective partitioning of the RF power to the helicon and ICRH systems, with the proper adjustment of the propellant flow. However, other complementary techniques are also being studied. Operational and performance considerations favor the light gases. The physics and engineering of this device have been under study since the late 1970s. A NASA-led, research effort, involving several terms in the United States, continues to explore the scientific and technological foundations of this concept. The research involves theory, experiment, engineering design, mission analysis, and technology development. Experimentally, high density, stable plasma discharges have been generated in Helium, Hydrogen and Deuterium, as well as mixtures of these gases. Key issues involve the optimization of the helicon discharge for high-density operation and the efficient coupling of ICRH to the plasma, prior to acceleration by the magnetic nozzle. Theoretically, the dynamics of the magnetized plasma are being studied from kinetic and fluid perspectives. Plasma acceleration by the magnetic nozzle and subsequent detachment has been demonstrated in numerical simulations. These results are presently undergoing experimental verification. A brisk technology development effort for space-qualified, compact, solid-state RF equipment, and high temperature superconducting magnets is under way in support of this project. A conceptual point design for an early space demonstrator on the International Space Station has been defined

  6. Comparison between helium and argon plasma jets on improving the hydrophilic property of PMMA surface

    NASA Astrophysics Data System (ADS)

    Wang, Ruixue; Shen, Yuan; Zhang, Cheng; Yan, Ping; Shao, Tao

    2016-03-01

    In this paper, a plasma jet driven by an in-house developed microsecond pulse is used for polymethyl methacrylate (PMMA) surface modification. The hydrophilic modification effects of He and Ar plasma jets are compared under the same condition. The He and Ar plasma jets are characterized by optical emission spectrometer (OES). Water contact angle (WCA) measurement is used to evaluate the wettability of PMMA samples. The evolution on morphology and chemical composition of PMMA before and after plasma treatment are also analyzed. The OES results demonstrate that He plasma is composed with higher intensities of reactive species, like OH, O, N2 and N2+ than that of Ar plasma and show a better modification effect. In addition, it is observed that the surface roughness and oxygen-containing groups like Csbnd O/Csbnd OH and Odbnd Csbnd O increase on the PMMA surface after plasma treatment, which are responsible for the hydrophilic modification. During the storage, the WCA of each sample increases gradually for both He and Ar plasma treatments. The He plasma treated PMMA also shows a slower aging effect than that of Ar plasma treated PMMA.

  7. Surface Plasma Arc by Radio-Frequency Control Study (SPARCS)

    SciTech Connect

    Ruzic, David N.

    2013-04-29

    This paper is to summarize the work carried out between April 2012 and April 2013 for development of an experimental device to simulate interactions of o -normal detrimental events in a tokamak and ICRF antenna. The work was mainly focused on development of a pulsed plasma source using theta pinch and coaxial plasma gun. This device, once completed, will have a possible application as a test stand for high voltage breakdown of an ICRF antenna in extreme events in a tokamak such as edge-localized modes or disruption. Currently, DEVeX does not produce plasma with high temperature enough to requirement for an ELM simulator. However, theta pinch is a good way to produce high temperature ions. The unique characteristic of plasma heating by a theta pinch is advantageous for an ELM simulator due to its effective ion heating. The objective of the proposed work, therefore, is to build a test facility using the existing theta pinch facility in addition to a coaxial plasma gun. It is expected to produce a similar pulsed-plasma heat load to the extreme events in tokamaks and to be applied for studying interactions of hot plasma and ICRF antennas.

  8. Nonthermal atmospheric plasma rapidly disinfects multidrug-resistant microbes by inducing cell surface damage.

    PubMed

    Kvam, Erik; Davis, Brian; Mondello, Frank; Garner, Allen L

    2012-04-01

    Plasma, a unique state of matter with properties similar to those of ionized gas, is an effective biological disinfectant. However, the mechanism through which nonthermal or "cold" plasma inactivates microbes on surfaces is poorly understood, due in part to challenges associated with processing and analyzing live cells on surfaces rather than in aqueous solution. Here, we employ membrane adsorption techniques to visualize the cellular effects of plasma on representative clinical isolates of drug-resistant microbes. Through direct fluorescent imaging, we demonstrate that plasma rapidly inactivates planktonic cultures, with >5 log(10) kill in 30 s by damaging the cell surface in a time-dependent manner, resulting in a loss of membrane integrity, leakage of intracellular components (nucleic acid, protein, ATP), and ultimately focal dissolution of the cell surface with longer exposure time. This occurred with similar kinetic rates among methicillin-resistant Staphylococcus aureus (MRSA), Pseudomonas aeruginosa, and Candida albicans. We observed no correlative evidence that plasma induced widespread genomic damage or oxidative protein modification prior to the onset of membrane damage. Consistent with the notion that plasma is superficial, plasma-mediated sterilization was dramatically reduced when microbial cells were enveloped in aqueous buffer prior to treatment. These results support the use of nonthermal plasmas for disinfecting multidrug-resistant microbes in environmental settings and substantiate ongoing clinical applications for plasma devices.

  9. Surface modification of polyester fabric with plasma pretreatment and carbon nanotube coating for antistatic property improvement

    NASA Astrophysics Data System (ADS)

    Wang, C. X.; Lv, J. C.; Ren, Y.; Zhi, T.; Chen, J. Y.; Zhou, Q. Q.; Lu, Z. Q.; Gao, D. W.; Jin, L. M.

    2015-12-01

    This study introduced a green method to prepare antistatic polyester (PET) fabrics by plasma pretreatment and single-walled carbon nanotube (SWCNT) coating. The influences of plasma conditions and SWCNT coating parameters on antistatic property of PET fabrics were investigated. PET fabrics were pretreated under various plasma conditions such as different treatment times, output powers and working gases, and then SWCNT coating on the plasma treated PET fabrics was carried out by coating-dry-cure using various coating parameters including different SWCNT concentrations, curing times and curing temperatures. PET fabrics were characterized by scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and volume resistivity. SEM and XPS analysis of the plasma treated PET fabrics revealed the increase in surface roughness and oxygen/nitrogen containing groups on the PET fiber surface. SEM and XPS analysis of the plasma treated and SWCNT coated PET fabrics indicated the SWCNT coating on PET fiber surface. The plasma treated and SWCNT coated PET fabrics exhibited a good antistatic property, which increased and then decreased with the increasing plasma treatment time and output power. The antistatic property of the O2 plasma treated and SWCNT coated PET fabric was better and worse than that of N2 or Ar plasma treated and SWCNT coated PET fabric in the shorter treatment time and the longer treatment time, respectively. In addition, the antistatic property of the plasma treated and SWCNT coated PET fabrics also increased with the increasing SWCNT concentration, curing time and curing temperature in the range studied. Plasma conditions and SWCNT coating parameters had signally influence on the antistatic property of plasma treated and SWCNT coated PET fabrics. Therefore, adequate parameters should be carefully selected for the optimum antistatic property of the plasma treated and SWCNT coated PET fabrics.

  10. Effects of low-temperature surface-wave plasma treatment with various gases on surface modification of chitosan

    NASA Astrophysics Data System (ADS)

    Ogino, Akihisa; Kral, Martin; Yamashita, Mitsuji; Nagatsu, Masaaki

    2008-12-01

    The effect of low-temperature surface-wave plasma treatment with various gases on surface modification of chitosan was investigated using the surface-wave plasma. Chitosan is a nontoxic, biocompatible and biodegradable polymer. It is thought that an increase in amino groups, a key constituent of chitosan molecules, will be useful for biomedical applications, such as improvement of blood clotting properties, drug delivery system, prodrug using derivatization and so on. In this study, therefore, we have focused on the amino group introduction on chitosan surface by using Ar, O 2, NH 3 and NH 3-He mixed gas plasmas. The experimental results of X-ray photoelectron spectroscopy measurements showed that N/C atomic ratio increased from 6.8% to 14.7% after NH 3 plasma treatment. With O 2 plasma treatment, the surface roughness of chitosan film was significantly modified from 1.96 nm to 14.6 nm. The blood clotting time of the sample treated by NH 3 and He plasma with O 2 pretreatment was reduced to 55.2% of that of untreated one.

  11. Rocket Engine Turbine Blade Surface Pressure Distributions Experiment and Computations

    NASA Technical Reports Server (NTRS)

    Hudson, Susan T.; Zoladz, Thomas F.; Dorney, Daniel J.; Turner, James (Technical Monitor)

    2002-01-01

    Understanding the unsteady aspects of turbine rotor flow fields is critical to successful future turbine designs. A technology program was conducted at NASA's Marshall Space Flight Center to increase the understanding of unsteady environments for rocket engine turbines. The experimental program involved instrumenting turbine rotor blades with miniature surface mounted high frequency response pressure transducers. The turbine model was then tested to measure the unsteady pressures on the rotor blades. The data obtained from the experimental program is unique in two respects. First, much more unsteady data was obtained (several minutes per set point) than has been possible in the past. Also, an extensive steady performance database existed for the turbine model. This allowed an evaluation of the effect of the on-blade instrumentation on the turbine's performance. A three-dimensional unsteady Navier-Stokes analysis was also used to blindly predict the unsteady flow field in the turbine at the design operating conditions and at +15 degrees relative incidence to the first-stage rotor. The predicted time-averaged and unsteady pressure distributions show good agreement with the experimental data. This unique data set, the lessons learned for acquiring this type of data, and the improvements made to the data analysis and prediction tools are contributing significantly to current Space Launch Initiative turbine airflow test and blade surface pressure prediction efforts.

  12. Engineered antifouling microtopographies: surface pattern effects on cell distribution.

    PubMed

    Decker, Joseph T; Sheats, Julian T; Brennan, Anthony B

    2014-12-23

    Microtopography has been observed to lead to altered attachment behavior for marine fouling organisms; however, quantification of this phenomenon is lacking in the scientific literature. Here, we present quantitative measurement of the disruption of normal attachment behavior of the fouling algae Ulva linza by antifouling microtopographies. The distribution of the diatom Navicula incerta was shown to be unaffected by the presence of topography. The radial distribution function was calculated for both individual zoospores and cells as well as aggregates of zoospores from attachment data for a variety topographic configurations and at a number of different attachment densities. Additionally, the screening distance and maximum values were mapped according to the location of zoospore aggregates within a single unit cell. We found that engineered topographies decreased the distance between spore aggregates compared to that for a smooth control surface; however, the distributions for individual spores were unchanged. We also found that the local attachment site geometry affected the screening distance for aggregates of zoospores, with certain geometries decreasing screening distance and others having no measurable effect. The distribution mapping techniques developed and explored in this article have yielded important insight into the design parameters for antifouling microtopographies that can be implemented in the next generation of antifouling surfaces.

  13. Non-thermal plasma technology for the development of antimicrobial surfaces: a review

    NASA Astrophysics Data System (ADS)

    Nikiforov, Anton; Deng, Xiaolong; Xiong, Qing; Cvelbar, U.; DeGeyter, N.; Morent, R.; Leys, Christophe

    2016-05-01

    Antimicrobial coatings are in high demand in many fields including the biomaterials and healthcare sectors. Within recent progress in nanoscience and engineering at the nanoscale, preparation of nanocomposite films containing metal nanoparticles (such as silver nanoparticles, copper nanoparticles, zinc oxide nanoparticles) is becoming an important step in manufacturing biomaterials with high antimicrobial activity. Controlled release of antibiotic agents and eliminating free nanoparticles are of equal importance for engineering antimicrobial nanocomposite materials. Compared to traditional chemical ‘wet’ methods, plasma deposition and plasma polymerization are promising approaches for the fabrication of nanocomposite films with the advantages of gas phase dry processes, effective use of chemicals and applicability to various substrates. In this article, we present a short overview of state-of-the-art engineering of antimicrobial materials based on the use of non-thermal plasmas at low and atmospheric pressure.

  14. Surface chemistry and fundamental limitations on the plasma cleaning of metals

    NASA Astrophysics Data System (ADS)

    Dong, Bin; Driver, M. Sky; Emesh, Ismail; Shaviv, Roey; Kelber, Jeffry A.

    2016-10-01

    In-situ X-ray photoelectron spectroscopy (XPS) studies reveal that plasma cleaning of air-exposed Co or Cu transition metal surfaces results in the formation of a remnant C film 1-3 monolayers thick, which is not reduced upon extensive further plasma exposure. This effect is observed for H2 or NH3 plasma cleaning of Co, and He or NH3 plasma cleaning of Cu, and is observed with both inductively coupled (ICP) and capacitively-coupled plasma (CCP). Changes in C 1 s XPS spectra indicate that this remnant film formation is accompanied by the formation of carbidic C on Co and of graphitic C on Cu. This is in contrast to published work showing no such remnant carbidic/carbon layer after similar treatments of Si oxynitride surfaces. The observation of the remnant carbidic C film on Co and graphitic film on Cu, but not on silicon oxynitride (SiOxNy), regardless of plasma chemistry or type, indicates that this effect is due to plasma induced secondary electron emission from the metal surface, resulting in transformation of sp3 adventitious C to either a metal carbide or graphite. These results suggest fundamental limitations to plasma-based surface cleaning procedures on metal surfaces.

  15. 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.

  16. Solar Wind Access to Lunar Polar Craters: Feedback Between Surface Charging and Plasma Expansion

    NASA Technical Reports Server (NTRS)

    Zimmerman, M. I.; Farrell, W. M.; Stubbs, T. J.; Halekas, J. S.; Jackson, T. L.

    2011-01-01

    Determining the plasma environment within permanently shadowed lunar craters is critical to understanding local processes such as surface charging, electrostatic dust transport, volatile sequestration, and space weathering. In order to investigate the nature of this plasma environment, the first two-dimensional kinetic simulations of solar wind expansion into a lunar crater with a self-consistent plasma-surface interaction have been undertaken. The present results reveal how the plasma expansion into a crater couples with the electrically-charged lunar surface to produce a quasi-steady wake structure. In particular, there is a negative feedback between surface charging and ambipolar wake potential that allows an equilibrium to be achieved, with secondary electron emission strongly moderating the process. A range of secondary electron yields is explored, and two distinct limits are highlighted in which either surface charging or ambipoiar expansion is responsible for determining the overall wake structure.

  17. Effects of the modified materials on plasma in surface modification by plasma

    NASA Astrophysics Data System (ADS)

    Katoh, Masaaki; Miyazaki, Hirokatu; Miyashita, Kiyoshi; Ohi, Seiya; Tajima, Kenichi; Ohte, Takeo; Kojima, Akira; Ohtani, Sugio

    2001-01-01

    We have developed an in situ system in which material can be inserted into and removed from the plasma apparatus in order to measure the transient variations of plasma with minimum changes in discharge chamber and measurement vessel. By using this system, the transient variations of O 2+ ion, O + ion, O radical, electron temperature and electron density were measured when the materials were put into and taken out from the oxygen plasma. Also, the difference between the steady state value without material in the plasma and that with material, in relation to each parameter, was measured. The following facts were found in this study. O 2+ and O + mass spectra decreased when the material was inserted into plasma. Then it returned to the original value when the material was taken out. The condition of the transient change of O 2+ differed remarkably according to the material. By optical emission analysis intensity of O radical was observed more remarkably than that of O 2 ion. Whatever the material was, the transient change did not vary much. The electron density greatly decreased by the material being included into the plasma. However, the electron temperature was constant even if the material was inserted into the plasma. The reflection power was constant by putting material in and out of plasma whatever the material was. The weight decrease in case of Teflon was larger than the other materials after the treatment in the same plasma condition.

  18. Radio-frequency Ar plasma treatment on muga silk fiber: correlation between physicochemical and surface morphology

    NASA Astrophysics Data System (ADS)

    Gogoi, Dolly; Chutia, Joyanti; Choudhury, Arup Jyoti; Pal, Arup Ratan; Patil, Dinkar

    2012-11-01

    Radio-frequency (RF) Ar plasma treatment is carried out on natural muga silk fibers in a capacitively coupled plasma reactor. The physical and thermal properties of the muga fibers are investigated at an RF power of 20 W and in the treatment time range of 5 to 20 min. The virgin and plasma-treated muga fibers are characterized by Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy. The effect of Ar plasma treatment can be observed only on the outermost layer of the muga fibers without any significant variation in their bulk and thermal properties, as supported by differential scanning calorimetry and thermogravimetric analysis. Improvement in tensile strength and hydrophobicity of the plasma-treated muga fibers is observed at lower treatment time and RF power. Attempts are made to correlate the properties of the plasma-treated muga fibers with their surface chemistry and surface morphologies.

  19. Landau damping of the dust-acoustic surface waves in a Lorentzian dusty plasma slab

    SciTech Connect

    Lee, Myoung-Jae; Jung, Young-Dae

    2016-01-15

    Landau damping of a dust-acoustic surface wave propagating at the interfaces of generalized Lorentzian dusty plasma slab bounded by a vacuum is kinetically derived as the surface wave displays the symmetric and the anti-symmetric mode in a plasma slab. In the limiting case of small scaled wave number, we have found that Landau damping is enhanced as the slab thickness is increased. In particular, the damping of anti-symmetric mode is much stronger for a Lorentzian plasma than for a Maxwellian plasma. We have also found that the damping is more affected by superthermal particles in a Lorentzian plasma than by a Maxwellian plasma for both of the symmetric and the anti-symmetric cases. The variations of Landau damping with various parameters are also discussed.

  20. High-order harmonics from laser-irradiated plasma surfaces

    SciTech Connect

    Teubner, U.; Gibbon, P.

    2009-04-15

    The investigation of high-order harmonic generation (HHG) of femtosecond laser pulses by means of laser-produced plasmas is surveyed. This kind of harmonic generation is an alternative to the HHG in gases and shows significantly higher conversion efficiency. Furthermore, with plasma targets there is no limitation on applicable laser intensity and thus the generated harmonics can be much more intense. In principle, harmonic light may also be generated at relativistic laser intensity, in which case their harmonic intensities may even exceed that of the focused laser pulse by many orders of magnitude. This phenomenon presents new opportunities for applications such as nonlinear optics in the extreme ultraviolet region, photoelectron spectroscopy, and opacity measurements of high-density matter with high temporal and spatial resolution. On the other hand, HHG is strongly influenced by the laser-plasma interaction itself. In particular, recent results show a strong correlation with high-energy electrons generated during the interaction process. The harmonics are a promising tool for obtaining information not only on plasma parameters such as the local electron density, but also on the presence of large electric and magnetic fields, plasma waves, and the (electron) transport inside the target. This paper reviews the theoretical and experimental progress on HHG via laser-plasma interactions and discusses the prospects for applying HHG as a short-wavelength, coherent optical tool.

  1. 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.

  2. Thermal fluctuations and emission of surface waves escaping from a nonuniform plasma

    NASA Astrophysics Data System (ADS)

    Aliev, Iu. M.; Vukovich, S.; Gradov, O. M.; Kirii, A. Iu.; Frolov, A. A.

    1980-07-01

    Attention is given to fluctuations of leaky surface waves, quasi-localized at a plasma-density discontinuity. Correlation functions of electromagnetic field fluctuations are obtained which determine the spectral intensity of thermal emission from the plasma. It is shown that measurements of angular intensity distribution, line width, and threshold angle can be used to study plasma density distribution, characteristic inhomogeneity scales, and temperature at the discontinuity.

  3. Characterization of an atmospheric pressure air plasma source for polymer surface modification

    NASA Astrophysics Data System (ADS)

    Yang, Shujun; Tang, Jiansheng

    2013-10-01

    An atmospheric pressure air plasma source was generated through dielectric barrier discharge (DBD). It was used to modify polyethyleneterephthalate (PET) surfaces with very high throughput. An equivalent circuit model was used to calculate the peak average electron density. The emission spectrum from the plasma was taken and the main peaks in the spectrum were identified. The ozone density in the down plasma region was estimated by Absorption Spectroscopy. NSF and ARC-ODU

  4. Surface modification of carbon nanohorns by helium plasma and ozone treatments

    NASA Astrophysics Data System (ADS)

    Lin, Zaw; Iijima, Toru; Selvam Karthik, Paneer; Yoshida, Mitsunobu; Hada, Masaki; Nishikawa, Takeshi; Hayashi, Yasuhiko

    2017-01-01

    In this paper, we describe the effects of helium plasma and ozone treatments on the dispersibility of carbon nanohorns (CNHs) in water. The experimental setups have been designed to efficiently generate helium plasma and ozone by dielectric barrier discharge at atmospheric pressure. After being treated with ozone, the oxygen-containing functional groups were introduced to the surface of CNHs, and are responsible for better dispersion. Helium plasma treatment was performed separately and it resulted in hydroxyl functional groups on the surface of CNHs. It was also found that the sizes of CNHs in water were smaller after ozone treatment. However, plasma-treated CNHs were bigger than ozone treated CNHs. The dispersed CNHs modified by ozone treatment were stable for more than three months without precipitation. In contrast, though helium plasma treatment introduced hydroxyl groups to the surface of CNHs, the dispersibility decreased and the flocculation of CNHs was observed in a few minutes.

  5. Contribution of material’s surface layer on charge state distribution in laser ablation plasma

    SciTech Connect

    Kumaki, Masafumi; Steski, Dannie; Kanesue, Takeshi; Ikeda, Shunsuke; Okamura, Masahiro; Washio, Masakazu

    2016-02-15

    To generate laser ablation plasma, a pulse laser is focused onto a solid target making a crater on the surface. However, not all the evaporated material is efficiently converted to hot plasma. Some portion of the evaporated material could be turned to low temperature plasma or just vapor. To investigate the mechanism, we prepared an aluminum target coated by thin carbon layers. Then, we measured the ablation plasma properties with different carbon thicknesses on the aluminum plate. The results showed that C{sup 6+} ions were generated only from the surface layer. The deep layers (over 250 nm from the surface) did not provide high charge state ions. On the other hand, low charge state ions were mainly produced by the deeper layers of the target. Atoms deeper than 1000 nm did not contribute to the ablation plasma formation.

  6. Fabrication of thromboresistant multilayer thin film on plasma treated poly (vinyl chloride) surface.

    PubMed

    Tan, Qinggang; Ji, Jian; Zhao, Feng; Fan, De-Zeng; Sun, Fu-Yu; Shen, Jia-Cong

    2005-07-01

    Layer-by-layer deposited anticoagulant multilayer films were prepared on ammonia plasma treated poly (vinyl chloride) (PVC). Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR) and contact angle results revealed the presence of -NH2 on the ammonia plasma treated PVC surfaces and the layer-by-layer self-assembly process. The stability of multilayer film was studied with the radio labeled method. The remainder bovine serum albumin (BSA) in cross-linked 5(heparin/BSA) multilayer films dipped in phosphate buffered saline (PBS, pH 7.4) was more than 90% in 40 days. The static platelet adhesion result indicated the anticoagulant multilayer films deposited on the plasma treated PVC reduced platelet adhesion drastically and no thrombus forming. The plasma recalcification time revealed that the multilayer modified surfaces greatly prolonged the plasma recalcification time. Such an easy processing and shape-independent method may have good potential for surface modification of cardiovascular devices.

  7. Metal ceramic alloy structure and surface layer modification during electron-ion-plasma irradiation of its surface

    NASA Astrophysics Data System (ADS)

    Ovcharenko, V. E.; Ivanov, Yu. F.; Shilko, E. V.; Mokhovikov, A. A.; Baohai, Yu; Tianyng, Xiong; Hua, Xu Yun; Lisheng, Zhong

    2016-11-01

    The paper presents research findings on the problems of electron-beam irradiation in noble gases plasma with different indexes of ionizing energy and atomic weight, and a surface layer structure modification versus a surface layer microhardness, wear and bending resistances and corrosion stability of 50% TiC/50% (Ni + 20% Cr) metal ceramic alloy samples. Discussions on the issues of the ways impulse electron-beam irradiation in the conditions of various types of noble gas plasma influences the mechanism of a metal ceramic alloy surface layer structure-phase state modification has been also presented.

  8. Production of a biofunctional titanium surface using plasma electrolytic oxidation and glow-discharge plasma for biomedical applications.

    PubMed

    Beline, Thamara; Marques, Isabella da Silva Vieira; Matos, Adaias O; Ogawa, Erika S; Ricomini-Filho, Antônio P; Rangel, Elidiane C; da Cruz, Nilson Cristino; Sukotjo, Cortino; Mathew, Mathew T; Landers, Richard; Consani, Rafael L X; Mesquita, Marcelo Ferraz; Barão, Valentim Adelino Ricardo

    2016-03-16

    In this study, the authors tested the hypotheses that plasma electrolytic oxidation (PEO) and glow-discharge plasma (GDP) would improve the electrochemical, physical, chemical, and mechanical properties of commercially pure titanium (cpTi), and that blood protein adsorption on plasma-treated surfaces would increase. Machined and sandblasted surfaces were used as controls. Standard electrochemical tests were conducted in artificial saliva (pHs of 3.0, 6.5, and 9.0) and simulated body fluid. Surfaces were characterized by scanning electron microscopy, energy-dispersive spectroscopy, x-ray photoelectron spectroscopy, atomic force microscopy, x-ray diffraction, profilometry, Vickers microhardness, and surface energy. For biological assay, the adsorption of blood serum proteins (i.e., albumin, fibrinogen, and fibronectin) was tested. Higher values of polarization resistance and lower values of capacitance were noted for the PEO and GDP groups (p < 0.05). Acidic artificial saliva reduced the corrosion resistance of cpTi (p < 0.05). PEO and GDP treatments improved the surface properties by enrichment of the surface chemistry with bioactive elements and increased surface energy. PEO produced a porous oxide layer (5-μm thickness), while GDP created a very thin oxide layer (0.76-μm thickness). For the PEO group, the authors noted rutile and anatase crystalline structures that may be responsible for the corrosion barrier improvement and increased microhardness values. Plasma treatments were able to enhance the surface properties and electrochemical stability of titanium, while increasing protein adsorption levels.

  9. Simulation of plasma-surface interactions in a fusion reactor by means of QSPA plasma streams: recent results and prospects

    NASA Astrophysics Data System (ADS)

    Garkusha, I. E.; Aksenov, N. N.; Byrka, O. V.; Makhlaj, V. A.; Herashchenko, S. S.; Malykhin, S. V.; Petrov, Yu V.; Staltsov, V. V.; Surovitskiy, S. V.; Wirtz, M.; Linke, J.; Sadowski, M. J.; Skladnik-Sadowska, E.

    2016-09-01

    This paper is devoted to plasma-surface interaction issues at high heat-loads which are typical for fusion reactors. For the International Thermonuclear Experimental Reactor (ITER), which is now under construction, the knowledge of erosion processes and the behaviour of various constructional materials under extreme conditions is a very critical issue, which will determine a successful realization of the project. The most important plasma-surface interaction (PSI) effects in 3D geometry have been studied using a QSPA Kh-50 powerful quasi-stationary plasma accelerator. Mechanisms of the droplet and dust generation have been investigated in detail. It was found that the droplets emission from castellated surfaces has a threshold character and a cyclic nature. It begins only after a certain number of the irradiating plasma pulses when molten and shifted material is accumulated at the edges of the castellated structure. This new erosion mechanism, connected with the edge effects, results in an increase in the size of the emitted droplets (as compared with those emitted from a flat surface). This mechanism can even induce the ejection of sub-mm particles. A concept of a new-generation QSPA facility, the current status of this device maintenance, and prospects for further experiments are also presented.

  10. Radiation characteristics of input power from surface wave sustained plasma antenna

    NASA Astrophysics Data System (ADS)

    Naito, T.; Yamaura, S.; Fukuma, Y.; Sakai, O.

    2016-09-01

    This paper reports radiation characteristics of input power from a surface wave sustained plasma antenna investigated theoretically and experimentally, especially focusing on the power consumption balance between the plasma generation and the radiation. The plasma antenna is a dielectric tube filled with argon and small amount of mercury, and the structure is a basic quarter wavelength monopole antenna at 2.45 GHz. Microwave power at 2.45 GHz is supplied to the plasma antenna. The input power is partially consumed to sustain the plasma, and the remaining part is radiated as a signal. The relationship between the antenna gain and the input power is obtained by an analytical derivation and numerical simulations. As a result, the antenna gain is kept at low values, and most of the input power is consumed to increase the plasma volume until the tube is filled with the plasma whose electron density is higher than the critical electron density required for sustaining the surface wave. On the other hand, the input power is consumed to increase the electron density after the tube is fully filled with the plasma, and the antenna gain increases with increasing the electron density. The dependence of the antenna gain on the electron density is the same as that of a plasma antenna sustained by a DC glow discharge. These results are confirmed by experimental results of the antenna gain and radiation patterns. The antenna gain of the plasma is a few dB smaller than that of the identical metal antenna. The antenna gain of the plasma antenna is sufficient for the wireless communication, although it is difficult to substitute the plasma antenna for metal antennas completely. The plasma antenna is suitable for applications having high affinity with the plasma characteristics such as low interference and dynamic controllability.

  11. 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.

  12. Surface treatment of a titanium implant using low temperature atmospheric pressure plasmas

    NASA Astrophysics Data System (ADS)

    Lee, Hyun-Young; Tang, Tianyu; Ok, Jung-Woo; Kim, Dong-Hyun; Lee, Ho-Jun; Lee, Hae June

    2015-09-01

    During the last two decades, atmospheric pressure plasmas(APP) are widely used in diverse fields of biomedical applications, reduction of pollutants, and surface treatment of materials. Applications of APP to titanium surface of dental implants is steadily increasing as it renders surfaces wettability and modifies the oxide layer of titanium that hinders the interaction with cells and proteins. In this study, we have treated the titanium surfaces of screw-shaped implant samples using a plasma jet which is composed of a ceramic coaxial tube of dielectrics, a stainless steel inner electrode, and a coper tube outer electrode. The plasma ignition occurred with Ar gas flow between two coaxial metal electrodes and a sinusoidal bias voltage of 3 kV with a frequency of 20 kHz. Titanium materials used in this study are screw-shaped implants of which diameter and length are 5 mm and 13 mm, respectively. Samples were mounted at a distance of 5 mm below the plasma source, and the plasma treatment time was set to 3 min. The wettability of titanium surface was measured by the moving speed of water on its surface, which is enhanced by plasma treatment. The surface roughness was also measured by atomic force microscopy. The optimal condition for wettability change is discussed.

  13. Fibroblastic response and surface characterization of O(2)-plasma-treated thermoplastic polyetherurethane.

    PubMed

    Schlicht, Henning; Haugen, Håvard J; Sabetrasekh, Roya; Wintermantel, Erich

    2010-04-01

    Injection-molded samples of thermoplastic polyetherurethane (TPU) were treated with low-temperature oxygen plasma for different processing times in order to enhance cellular attachment for a gastric implant. Its effects were investigated by contact angle measurement, surface topography, cytotoxicity and cell colonization tests. No significant changes were found in the surface roughness of plasma treatment with plasma treatment time of less than 5 min. Longer treatment showed significantly higher surface roughness. It seems that there was a link between the changes in contact angle and enhanced cell growth on the treated surface, although only for the range up to plasma treatment times of 3 min. Prolonged treatment times did not cause any major changes in the water contact angle, but strongly improved the number of growing cells on the surface. Plasma treatment for 3-7 min led to a twofold increase in the number of cells compared to untreated samples and did not significantly alter the WST-1 nor worsened the lactate dehydrogenase activity compared to the control. Thus, it appears that O(2) plasma treatment is a suitable surface modification method for a gastric implant made of TPU in order to improve surface cell attachment where 3-7 min is the recommended treatment time.

  14. in situ plasma removal of surface contaminants from ion trap electrodes

    SciTech Connect

    Haltli, Raymond A.

    2015-04-01

    This research resulted in a construction and implementation of an in situ plasma discharge to remove surface contaminants from electrodes in an ion trapping experimental system is presented with results.

  15. Influence of surface finish on the plasma formation at the skin explosion

    NASA Astrophysics Data System (ADS)

    Datsko, I. M.; Chaikovsky, S. A.; Labetskaya, N. A.; Rybka, D. V.; Oreshkin, V. I.; Khishchenko, K. V.

    2016-11-01

    The paper reports on experiments to investigate how the quality of surface finish, i.e., surface roughness, influences the plasma formation in a skin explosion of conductors. The experiments were performed on a MIG terawatt generator with a current amplitude of up to 2.5 MA and current rise time of 100 ns. The plasma formation at the conductor surface and the evolution of the plasma boundary was recorded using a four-frame optical camera with an exposure time of 3 ns per frame. It is shown that the quality of surface finish little affects the onset of plasma formation in a skin explosion of stainless steel and St3 steel conductors at a magnetic field of up to 400 T.

  16. Surface Modification of Poly Vinyl Chloride (PVC) Using Low Pressure Argon and Oxygen Plasma

    NASA Astrophysics Data System (ADS)

    Mahmood, Ghoranneviss; Sheila, Shahidi; Jakub, Wiener

    2010-04-01

    In this study, commercial poly vinyl chloride (PVC) films were treated by oxygen and argon plasmas in a cylindrical glass tube which was surrounded by a DC variable magnetic field, with different sample positions in the plasma reactor and also different exposure durations. Effects of the plasma treatment on the hydrophilic properties of the films were studied by measuring the water drop contact angle on the surface of the samples. The surface topography of the untreated and plasma treated films was analyzed and compared by atomic force microscopy (AFM). The optical characteristic changes in treated samples were investigated using reflective spectrophotometry. Also, the chemical changes which appeared on the surface of the samples were investigated using Fourier transform infrared spectroscopy (FTIR). The results show that the plasma treated PVC becomes more hydrophilic with an enhanced wettability. A sharp decrease in the water contact angle may also be a consequence of the surface texturization. The aging effect on wettability of the samples was also investigated. The results show that the effect of oxygen plasma on the surface properties of the samples is more pronounced compared with that of argon plasma.

  17. The exchange-correlation effects on surface plasmon oscillations in semi-bounded quantum plasma

    SciTech Connect

    Shahmansouri, Mehran

    2015-09-15

    We studied the surface plasmon waves in a quantum plasma half-space by considering the effects of exchange and correlation for the electrons. We used a quantum hydrodynamic approach, including the full set of Maxwell equations and considering two new quantities (measuring the exchange and correlation effects) in addition to the Fermi electron temperature and the quantum Bohm potential, to derive the dispersion relation for the surface plasmon waves. It was found that the exchange-correlation effects significantly modified the behavior of surface plasmon waves. We showed that the frequency of surface plasmon wave was down-shifted by the exchange-correlation effects. On the other hand, the quantum effects (including of the exchange-correlation effects and the quantum Bohm potential) was seen to cause an increase in the phase speed of surface plasmon waves. Our results can help to understand the propagation properties of surface waves in intense laser produced solid density plasmas and metallic plasmas.

  18. Ellipsoidal Colloids with a Controlled Surface Roughness via Bioinspired Surface Engineering: Building Blocks for Liquid Marbles and Superhydrophobic Surfaces.

    PubMed

    Zhang, Pengjiao; Yang, Lu; Li, Qiang; Wu, Songhai; Jia, Shaoyi; Li, Zhanyong; Zhang, Zhenkun; Shi, Linqi

    2017-03-01

    Understanding the important role of the surface roughness of nano/colloidal particles and harnessing them for practical applications need novel strategies to control the particles' surface topology. Although there are many examples of spherical particles with a specific surface roughness, nonspherical ones with similar surface features are rare. The current work reports a one-step, straightforward, and bioinspired surface engineering strategy to prepare ellipsoidal particles with a controlled surface roughness. By manipulating the unique chemistry inherent to the oxidation-induced self-polymerization of dopamine into polydopamine (PDA), PDA coating of polymeric ellipsoids leads to a library of hybrid ellipsoidal particles (PS@PDA) with a surface that decorates with nanoscale PDA protrusions of various densities and sizes. Together with the advantages originated from the anisotropy of ellipsoids and rich chemistry of PDA, such a surface feature endows these particles with some unique properties. Evaporative drying of fluorinated PS@PDA particles produces a homogeneous coating with superhydrophobicity that arises from the two-scale hierarchal structure of microscale interparticle packing and nanoscale roughness of the constituent ellipsoids. Instead of water repelling that occurs for most of the lotus leaf-like superhydrophobic surfaces, such coating exhibits strong water adhesion that is observed with certain species of rose pedals. In addition, the as-prepared hybrid ellipsoids are very efficient in preparing liquid marble-isolated droplets covered with solid particles. Such liquid marbles can be placed onto many surfaces and might be useful for the controllable transport and manipulation of small volumes of liquids.

  19. Inorganic Surface Engineering to Enhance Perovskite Solar Cell Efficiency.

    PubMed

    Aeineh, Naemeh; Barea, Eva M; Behjat, Abbas; Sharifi, Nafiseh; Mora-Sero, Ivan

    2017-03-29

    The photoconversion efficiency of perovskite solar cells (PSCs) has been enhanced by the deposition of inorganic nanoparticles (NPs) at the interface between the compact TiO2 electron selective contact and the mesoporous TiO2 film. The NPs used have been core/shell Au@SiO2, where a thin SiO2 coating protects the Au core from the direct chemical interaction with CH3NH3PbI3 halide perovskite used as light harvesting material. Samples prepared with the Au@SiO2 NPs exhibits higher external quantum efficiency in all the complete wavelength range at which perovskite presents light absorption and not just at the wavelengths at which Au@SiO2 NPs presents their absorption peak. This fact rules out a direct plasmonic process as the responsible on cell performance enhancement. A detail characterization by photoluminescence, impedance spectroscopy and open circuit voltage decay unveil a modification of the interfacial properties with an augmentation of the interfacial electrostatic potential that increases both photovoltage and photocurrent. This work highlights the dramatic role of interfaces in PSC performance. The use of reduced quantities of highly stable inorganic compounds to modify the PSC interface instead of the extensively used organic compounds opens the door to a new surface engineering based on inorganic compounds.

  20. Plasma-enhanced synthesis of surfaces that kill bacteria on contact

    NASA Astrophysics Data System (ADS)

    Jampala, Soujanya Naga

    High incidences of microbial contamination and infections are a major concern in all existing and evolving technologies of medicine and biology. The propensity towards infections is directly related to bacterial colonization and biofilms on surfaces. This dissertation presents the development of surfaces that can kill bacteria on contact by using cold plasma technology. Quaternary ammonium (QA) groups are known to exhibit antibacterial characteristics in water-based environments. To overcome the limitations of residual toxicity, alternative strategies involving covalent attachment of QA groups to metallic and cellulosic surfaces have been developed. Low pressure, non-equilibrium plasma-enhanced functionalization and subsequent ex situ chemical reactions were designed for step-by-step "bottom-up" chemical synthesis of QA groups covalently anchored to surfaces. The plasma processes under selected discharge parameters generated structure- and functionality-controlled crosslinked networks of macromolecular layers with high concentrations of reactive amine groups. Subsequent derivatization of the plasma-deposited films with alkyl halides yielded surface-bound QA groups rendering surfaces with high bactericidal efficacy against Gram-positive Staphylococcus aureus and Gram-negative Klebsiella pneumoniae. Stainless steel and cotton surfaces sequentially treated with ethylene diamine plasma, n-hexyl bromide and methyl iodide exhibited at least 99.9% and 98% kill of S. aureus and K. pneumoniae respectively. The influence of chemical architecture of QA groups with different alkyl substituents on the efficacy of bactericidal surfaces was quantified. Results from this work will permit the development of novel plasma-aided technologies for the synthesis of antibacterial surfaces with potential biomedical applications. The cold plasma approach can be used on any solid material surfaces including polymers, metals, ceramics and semiconductors.

  1. Hydrogen desorption kinetics for aqueous hydrogen fluoride and remote hydrogen plasma processed silicon (001) surfaces

    SciTech Connect

    King, Sean W. Davis, Robert F.; Carter, Richard J.; Schneider, Thomas P.; Nemanich, Robert J.

    2015-09-15

    The desorption kinetics of molecular hydrogen (H{sub 2}) from silicon (001) surfaces exposed to aqueous hydrogen fluoride and remote hydrogen plasmas were examined using temperature programmed desorption. Multiple H{sub 2} desorption states were observed and attributed to surface monohydride (SiH), di/trihydride (SiH{sub 2/3}), and hydroxide (SiOH) species, subsurface hydrogen trapped at defects, and hydrogen evolved during the desorption of surface oxides. The observed surface hydride species were dependent on the surface temperature during hydrogen plasma exposure with mono, di, and trihydride species being observed after low temperature exposure (150 °C), while predominantly monohydride species were observed after higher temperature exposure (450 °C). The ratio of surface versus subsurface H{sub 2} desorption was also found to be dependent on the substrate temperature with 150 °C remote hydrogen plasma exposure generally leading to more H{sub 2} evolved from subsurface states and 450 °C exposure leading to more H{sub 2} desorption from surface SiH{sub x} species. Additional surface desorption states were observed, which were attributed to H{sub 2} desorption from Si (111) facets formed as a result of surface etching by the remote hydrogen plasma or aqueous hydrogen fluoride treatment. The kinetics of surface H{sub 2} desorption were found to be in excellent agreement with prior investigations of silicon surfaces exposed to thermally generated atomic hydrogen.

  2. Aerosol-assisted plasma deposition of hydrophobic polycations makes surfaces highly antimicrobial.

    PubMed

    Liu, Harris; Kim, Yoojeong; Mello, Kerrianne; Lovaasen, John; Shah, Apoorva; Rice, Norman; Yim, Jacqueline H; Pappas, Daphne; Klibanov, Alexander M

    2014-02-01

    The currently used multistep chemical synthesis for making surfaces antimicrobial by attaching to them hydrophobic polycations is replaced herein by an aerosol-assisted plasma deposition procedure. To this end, N,N-hexyl,methyl-PEI (HMPEI) is directly plasma-coated onto a glass surface. The resultant immobilized HMPEI coating has been thoroughly characterized and shown to be robust, bactericidal against Escherichia coli, and virucidal against human influenza virus.

  3. Surface functionalization of macroporous polymeric materials by treatment with air low temperature plasma.

    PubMed

    Molina, R; Sole, I; Vílchez, A; Bertran, E; Solans, C; Esquena, J

    2013-04-01

    Polystyrene/divinylbenzene (PS-DVB) macroporous monoliths obtained using highly concentrated emulsions as templates show a superhydrophobic behaviour, restricting their potential technological applications, especially those related to adhesion and wetting. Air plasma treatments were carried out in order to modulate wetting properties, modifying the surface chemical composition of macroporous polystyrene/divinylbenzene materials. The superhydrophobic behaviour was rapidly suppressed by air plasma treatment, greatly reducing the water contact angle, from approximately 150 degrees to approximately 90 degrees, in only 10 seconds of treatment. The new surface chemical groups, promoted by plasma active species, were characterized by surface analysis techniques with different depth penetration specificity (contact angle, XPS, FTIR and SEM). Results demonstrated that very short treatment times produced different chemical functionalities, mainly C-O, C=O, O-C=O and C-N, which provide the materials with predominantly acidic surface properties. However, plasma active species did not penetrate deeply through the interconnected pores of the material. FTIR analysis evidenced that the new hydrophilic surface groups promoted by plasma active species are in a negligibly concentration compared to bulk chemical groups, and are located in a very thin surface region on the PS-DVB monolith surface (significantly below 2 microm). XPS analysis of treated monoliths revealed a progressive increase of oxygen and nitrogen content as a function of plasma treatment time. However, oxidation of the PS-DVB monoliths surface prevails over the incorporation of nitrogen atoms. Finally, SEM studies indicated that the morphology of the plasma treated PS-DVB does not significantly change even for the longest air plasma treatment time studied (120 s).

  4. Surface modification of several dental substrates by non-thermal, atmospheric plasma brush

    PubMed Central

    Chen, Mingsheng; Zhang, Ying; Driver, M. Sky; Caruso, Anthony N.; Yu, Qingsong; Wang, Yong

    2013-01-01

    Objective The purpose of this study was to reveal the effectiveness of non-thermal atmospheric plasma brush in surface wettability and modification of four dental substrates. Methods Specimens of dental substrates including dentin, enamel, and two composites Filtek Z250, Filtek LS Silorane were prepared (~2 mm thick, ~10 mm diameter). The prepared surfaces were treated for 5–45 s with a non-thermal atmospheric plasma brush working at temperatures from 36 to 38 °C. The plasma-treatment effects on these surfaces were studied with contact-angle measurement, X-ray photoemission spectroscopy (XPS) and scanning electron microscopy (SEM). Results The non-thermal atmospheric argon plasma brush was very efficient in improving the surface hydrophilicity of four substrates studied. The results indicated that water contact angle values decreased considerably after only 5 s plasma treatment of all these substrates. After 30 s treatment, the values were further reduced to <5°, which was close to a value for super hydrophilic surfaces. XPS analysis indicated that the percent of elements associated with mineral in dentin/enamel or fillers in the composites increased. In addition, the percent of carbon (%C) decreased while %O increased for all four substrates. As a result, the O/C ratio increased dramatically, suggesting that new oxygen-containing polar moieties were formed on the surfaces after plasma treatment. SEM surface images indicated that no significant morphology change was induced on these dental substrates after exposure to plasmas. Significance Without affecting the bulk properties, a super-hydrophilic surface could be easily achieved by the plasma brush treatment regardless of original hydrophilicity/hydrophobicity of dental substrates tested. PMID:23755823

  5. On the boil-off time of probe surfaces in plasmas

    SciTech Connect

    Fuentes, N.; Gratton, F.T.

    1986-10-01

    The time required for the melting of the surface of a glass-insulated probe inserted in a plasma is computed including the influence of plasma mass motion. This effect is relevant for probe measurements in moving current sheaths of electrical gas discharges. For dense plasma focus experiments, it is shown that time of formation of a transition layer of evaporated material is shorter than the ion relaxation time in the plasma and the transit time of the current sheath by the probe position.

  6. Mechanisms behind surface modification of polypropylene film using an atmospheric-pressure plasma jet

    NASA Astrophysics Data System (ADS)

    Shaw, David; West, Andrew; Bredin, Jerome; Wagenaars, Erik

    2016-12-01

    Plasma treatments are common for increasing the surface energy of plastics, such as polypropylene (PP), to create improved adhesive properties. Despite the significant differences in plasma sources and plasma properties used, similar effects on the plastic film can be achieved, suggesting a common dominant plasma constituent and underpinning mechanism. However, many details of this process are still unknown. Here we present a study into the mechanisms underpinning surface energy increase of PP using atmospheric-pressure plasmas. For this we use the effluent of an atmospheric-pressure plasma jet (APPJ) since, unlike most plasma sources used for these treatments, there is no direct contact between the plasma and the PP surface; the APPJ provides a neutral, radical-rich environment without charged particles and electric fields impinging on the PP surface. The APPJ is a RF-driven plasma operating in helium gas with small admixtures of O2 (0-1%), where the effluent propagates through open air towards the PP surface. Despite the lack of charged particles and electric fields on the PP surface, measurements of contact angle show a decrease from 93.9° to 70.1° in 1.4 s and to 35° in 120 s, corresponding to a rapid increase in surface energy from 36.4 mN m-1 to 66.5 mN m-1 in the short time of 1.4 s. These treatment effects are very similar to what is found in other devices, highlighting the importance of neutral radicals produced by the plasma. Furthermore, we find an optimum percentage of oxygen of 0.5% within the helium input gas, and a decrease of the treatment effect with distance between the APPJ and the PP surface. These observed effects are linked to two-photon absorption laser-induced fluorescence spectroscopy (TALIF) measurements of atomic oxygen density within the APPJ effluent which show similar trends, implying the importance of this radical in the surface treatment of PP. Analysis of the surface reveals a two stage mechanism for the production of polar

  7. Stability of silanols and grafted alkylsilane monolayers on plasma-activated mica surfaces.

    PubMed

    Liberelle, Benoît; Banquy, Xavier; Giasson, Suzanne

    2008-04-01

    We investigated the effect of physical and chemical modifications of mica surfaces induced by water vapor-based plasma treatments on the stability of silanols and grafted alkylsilane monolayers. The plasma-activated substrates were characterized using XPS, TOF-SIMS, and contact angle measurements. They revealed a large surface coverage of silanol groups (Si-OH) and a loss of aluminum atoms compared to freshly cleaved mica surfaces. The stability of plasma-induced silanol groups was investigated by contact angle measurements using ethylene glycol as a probe liquid. The Si-OH surface coverage decreased rapidly under vacuum or thermal treatment to give rise to hydrophobic dehydrated surfaces. The stability of end-grafted monofunctionalized n-alkylsilanes was investigated in different solvents and at different pH using water contact angle measurements. The degrafting of alkylsilanes from the activated mica was promoted in acidic aqueous solutions. This detachment was associated with the hydrolysis of covalent bonds between the alkylsilanes and the mica surface. The monolayer stability was enhanced by increasing the length of the alkyl chains that probably act as a hydrophobic protective layer against hydrolysis reactions. Stable alkylsilane monolayers in water with pH greater than 5.5 were obtained on mica surfaces activated at low plasma pressure. We attributed this stability to the loss of surface Al atoms induced by the plasma treatment.

  8. Method For Plasma Source Ion Implantation And Deposition For Cylindrical Surfaces

    DOEpatents

    Fetherston, Robert P. , Shamim, Muhammad M. , Conrad, John R.

    1997-12-02

    Uniform ion implantation and deposition onto cylindrical surfaces is achieved by placing a cylindrical electrode in coaxial and conformal relation to the target surface. For implantation and deposition of an inner bore surface the electrode is placed inside the target. For implantation and deposition on an outer cylindrical surface the electrode is placed around the outside of the target. A plasma is generated between the electrode and the target cylindrical surface. Applying a pulse of high voltage to the target causes ions from the plasma to be driven onto the cylindrical target surface. The plasma contained in the space between the target and the electrode is uniform, resulting in a uniform implantation or deposition of the target surface. Since the plasma is largely contained in the space between the target and the electrode, contamination of the vacuum chamber enclosing the target and electrodes by inadvertent ion deposition is reduced. The coaxial alignment of the target and the electrode may be employed for the ion assisted deposition of sputtered metals onto the target, resulting in a uniform coating of the cylindrical target surface by the sputtered material. The independently generated and contained plasmas associated with each cylindrical target/electrode pair allows for effective batch processing of multiple cylindrical targets within a single vacuum chamber, resulting in both uniform implantation or deposition, and reduced contamination of one target by adjacent target/electrode pairs.

  9. Plasma-Synthesized Silver Nanoparticles on Electrospun Chitosan Nanofiber Surfaces for Antibacterial Applications.

    PubMed

    Annur, Dhyah; Wang, Zhi-Kai; Liao, Jiunn-Der; Kuo, Changshu

    2015-10-12

    Chitosan nanofibers have been electrospun with poly(ethylene oxide) and silver nitrate, as a coelectrospinning polymer and silver nanoparticle precursor, respectively. The average diameter of the as-spun chitosan nanofibers with up to 2 wt % silver nitrate loading was approximately 130 nm, and there was no evidence of bead formation or polymer agglomeration. Argon plasma was then applied for surface etching and synthesis of silver nanoparticles via precursor decomposition. Plasma surface bombardment induced nanoparticle formation primarily on the chitosan nanofiber surfaces, and the moderate surface plasma etching further encouraged maximum exposure of silver nanoparticles. UV-vis spectra showed the surface plasmon resonance signature of silver nanoparticles. The surface-immobilized nanoparticles were visualized by TEM and were found to have average particle diameters as small as 1.5 nm. Surface analysis by infrared spectroscopy and X-ray photoelectron spectroscopy confirmed the interactions between the silver nanoparticles and chitosan molecules, as well as the effect of plasma treatment on the nanofiber surfaces. Finally, a bacteria inhibition study revealed that the antibacterial activity of the electrospun chitosan nanofibers correspondingly increased with the plasma-synthesized silver nanoparticles.

  10. Thermal shock behaviour of blisters on W surface during combined steady-state/pulsed plasma loading

    NASA Astrophysics Data System (ADS)

    Jia, Y. Z.; Liu, W.; Xu, B.; Luo, G.-N.; Li, C.; Qu, S. L.; Morgan, T. W.; De Temmerman, G.

    2015-09-01

    The thermal shock behaviour of blister-covered W surfaces during combined steady-state/pulsed plasma loading was studied by scanning electron microscopy and electron backscatter diffraction. The W samples were first exposed to steady-state D plasma to induce blisters on the surface, and then the blistered surfaces were exposed to steady-state/pulsed plasma. Growth and cracking of blisters were observed after the exposure to the steady-state/pulsed plasma, while no obvious damage occurred on the surface area not covered with blisters. The results confirm that blisters induced by D plasma might represent weak spots on the W surface when exposed to transient heat load of ELMs. The cracks on blisters were different from the cracks due to the transient heat loads reported before, and they were assumed to be caused by stress and strain due to the gas expansion inside the blisters during the plasma pulses. Moreover, most of cracks were found to appear on the blisters formed on grains with surface orientation near [1 1 1].

  11. Measurement of plasma wave frequency from absolute stimulated Raman scattering near the quarter-critical surface in a laser plasma

    NASA Astrophysics Data System (ADS)

    Villeneuve, D. M.; Bernard, J. E.; Baldis, H. A.

    1987-12-01

    Thomson scattering techniques were used to measure the frequency of plasma waves near the quarter-critical surface in a well-diagnosed plasma irradiated by a nanosecond CO2 laser with intensity ˜1014 W/cm2. The frequency ωp was shown to be less than ω0/2, in disagreement with the commonly used estimate ωp=ω0/2+ (9)/(8) (ve/c)2ω0. The theory of Afeyan and Williams [Phys. Fluids 28, 3397 (1985)] gives better agreement, and shows that the density scale length is more important than the temperature in determining the frequency shift.

  12. Surface plasma wave assisted second harmonic generation of laser over a metal film

    SciTech Connect

    Chauhan, Santosh; Parashar, J.

    2015-01-15

    Second harmonic generation of laser mode converted surface plasma wave (SPW) over a corrugated metal film is studied. The laser, impinged on the metal film, under attenuated total reflection configuration, excites SPW over the metal–vacuum interface. The excited SPW extends over a much wider surface area than the laser spot cross-section. It exerts a second harmonic ponderomotive force on metal electrons, imparting them velocity that beats with the surface ripple to produce a nonlinear current, driving resonant second harmonic surface plasma wave.

  13. Collaborative Research: Fundamental studies of plasma control using surface embedded electronic devices

    SciTech Connect

    Raja, Laxminarayan L.; PanneerChelvam, PremKumar; Levko, Dimtry

    2016-02-26

    The proposed study will investigate the effect of active electron injection of from electrode surfaces To the best of our knowledge, no such a study has ever been attempted even though it could lead to the formation of whole new classes of plasma based devices and systems. We are motivated by recent articles and simple theory which gives strong reason to believe that embedded electronic devices can be used to exert control over the SEE coefficient of semiconductor surfaces (and maybe other surface types as well). Furthermore, the research will explore how such sub-surface electronic devices can best be used to exert control over an associated plasma.

  14. Equations for solitary surface waves on a plasma cylinder

    NASA Astrophysics Data System (ADS)

    Stenflo, L.; Gradov, O. M.

    1986-08-01

    The theory for high-frequency envelope solitons, propagating along a plasma cylinder, is generalized. It is then shown that previously neglected second harmonic terms are of the same order of magnitude as the nonlinear density terms, if the axial wavelength is comparable, to, or larger than, the cylinder radius.

  15. Plasma relaxation mechanics of pulsed high power microwave surface flashover

    SciTech Connect

    Beeson, S.; Dickens, J.; Neuber, A.

    2013-09-15

    Microwave transmission and reflection characteristics of pulsed radio frequency field generated plasmas are elucidated for air, N{sub 2}, and He environments under pressure conditions ranging from 10 to 600 torr. The pulsed, low temperature plasma is generated along the atmospheric side of the dielectric boundary between the source (under vacuum) and the radiating environment with a thickness on the order of 5 mm and a cross sectional area just smaller than that of the waveguide. Utilizing custom multi-standard waveguide couplers and a continuous low power probing source, the scattering parameters were measured before, during, and after the high power microwave pulse with emphasis on the latter. From these scattering parameters, temporal electron density estimations (specifically the longitudinal integral of the density) were calculated using a 1D plane wave-excited model for analysis of the relaxation processes associated. These relaxation characteristics ultimately determine the maximum repetition rate for many pulsed electric field applications and thus are applicable to a much larger scope in the plasma community than just those related to high power microwaves. This manuscript discusses the diagnostic setup for acquiring the power measurements along with a detailed description of the kinematic and chemical behavior of the plasma as it decays down to its undisturbed state under various gas type and pressure conditions.

  16. Effects of in-situ NH3 post plasma treatment on the surface passivation layer

    NASA Astrophysics Data System (ADS)

    Lee, Kyung Dong; Kang, Min Gu; Kim, Young Do; Tark, Sung Ju; Park, Sungeun; Kim, Donghwan

    2011-12-01

    Hydrogenated silicon nitride (SiNx:H) using plasma enhanced chemical vapor deposition is widely used in photovoltaic industry as an antireflection coating and passivation layer. The samples with or without in-situ NH3 post-plasma treatment had the following structures: SiNx/N-type Si/SiNx versus in-situ NH3 post-plasma treated SiNx/N-type Si/SiNx. The wafer was dipped in saw-damage-etching solution and wet cleaning process was treated. After the dry process with N2 atmosphere, SiNx thin film was deposited on back surface. Then SiNx thin film was deposited on the front surface with or without in-situ NH3 post-plasma treatment process. In order to minimize the plasma induced surface damage, we used lower power than the process power during the NH3 post-plasma treatment. After the in-situ NH3 post-plasma-treatment, we analyzed the effect of this in-situ NH3 post-plasma-treatment for passivation. The minority carrier lifetime was observed by means of quasi-steady-state photoconductance and microwave photoconductance.

  17. The relationship between cellular adhesion and surface roughness for polyurethane modified by microwave plasma radiation.

    PubMed

    Keshel, Saeed Heidari; Azhdadi, S Neda Kh; Asefnejad, Azadeh; Asefnezhad, Azadeh; Sadraeian, Mohammad; Montazeri, Mohamad; Biazar, Esmaeil

    2011-01-01

    Surface modification of medical polymers is carried out to improve biocompatibility. In this study, conventional polyurethane was exposed to microwave plasma treatment with oxygen and argon gases for 30 seconds and 60 seconds. Attenuated total reflection Fourier transform infrared spectra investigations of irradiated samples indicated the presence of functional groups. Atomic force microscope images of samples irradiated with inert and active gases indicated the nanometric topography of the sample surfaces. Samples irradiated by oxygen plasma indicated high roughness compared with those irradiated by inert plasma for the different lengths of time. In addition, surface roughness increased with time, which can be due to a reduction of contact angle of samples irradiated by oxygen plasma. Contact angle analysis indicated a reduction in samples irradiated with both types of plasma. However, samples irradiated with oxygen plasma indicated lower contact angle compared with those irradiated by argon plasma. Cellular investigations with unrestricted somatic stem cells showed better adhesion, cell growth, and proliferation among samples radiated by oxygen plasma for longer than for normal samples.

  18. Influence of irradiation conditions on plasma evolution in laser-surface interaction

    NASA Astrophysics Data System (ADS)

    Hermann, J.; Boulmer-Leborgne, C.; Dubreuil, B.; Mihailescu, I. N.

    1993-09-01

    The plasma plume induced by pulsed CO2 laser irradiation of a Ti target at power densities up to 4×108 W cm-2 was studied by emission spectroscopy. Time- and space-resolved measurements were performed by varying laser intensity, laser temporal pulse shape, ambient gas pressure, and the nature of the ambient gas. Experimental results are discussed by comparison with usual models. We show that shock wave and plasma propagation depend critically on the ratio Ivap/Ii, Ivap being the intensity threshold for surface vaporization and Ii the plasma ignition threshold of the ambient gas. Spectroscopic diagnostics of the helium breakdown plasma show maximum values of electron temperature and electron density in the order of kTe˜10 eV and ne=1018 cm-3, respectively. The plasma cannot be described by local thermodynamic equilibrium modeling. Nevertheless, excited metal atoms appear to be in equilibrium with electrons, hence, they can be used like a probe to measure the electron temperature. In order to get information on the role of the plasma in the laser-surface interaction, Ti surfaces were investigated by microscopy after irradiation. Thus an enhanced momentum transfer from the plasma to the target due to the recoil pressure of the breakdown plasma could be evidenced.

  19. Elastic-plastic adhesive impacts of tungsten dust with metal surfaces in plasma environments

    NASA Astrophysics Data System (ADS)

    Ratynskaia, S.; Tolias, P.; Shalpegin, A.; Vignitchouk, L.; De Angeli, M.; Bykov, I.; Bystrov, K.; Bardin, S.; Brochard, F.; Ripamonti, D.; den Harder, N.; De Temmerman, G.

    2015-08-01

    Dust-surface collisions impose size selectivity on the ability of dust grains to migrate in scrape-off layer and divertor plasmas and to adhere to plasma-facing components. Here, we report first experimental evidence of dust impact phenomena in plasma environments concerning low-speed collisions of tungsten dust with tungsten surfaces: re-bouncing, adhesion, sliding and rolling. The results comply with the predictions of the model of elastic-perfectly plastic adhesive spheres employed in the dust dynamics code MIGRAINe for sub- to several meters per second impacts of micrometer-range metal dust.

  20. Low Temperature Plasma-Surface Interactions: From Computer Chips to Cancer Therapy

    NASA Astrophysics Data System (ADS)

    Graves, David

    2014-05-01

    Low temperature plasmas (LTPs) are virtually always bounded by surfaces and the nature of the interaction often dominates the plasma physics, chemistry and applications. In this talk, I will present an overview of low temperature plasma-surface interactions with an emphasis on what has been learned during the last several decades. The remarkable evolution of low pressure LTP etching technology and more recent developments in biomedical applications of atmospheric pressure LTP will serve as key examples. This work was supported by DoE and NSF.

  1. Negative ion production in the RF multiaperture surface-plasma source

    SciTech Connect

    Abdrashitov, G.; Belchenko, Yu. Dranichnikov, A.; Gorbovsky, A.; Kapitonov, V.; Kolmogorov, V.; Kondakov, A.; Konstantinov, S.; Sanin, A.; Selivanov, A.; Selivanov, P.; Shikhovtsev, I.; Stupishin, N.; Tiunov, M.; Ivanov, A.; Sotnikov, O.; Binderbauer, M.; Putvinski, S.; Smirnov, A.; Sevier, L.

    2015-04-08

    The experiments on negative hydrogen ion beam production in a multi-aperture long-pulse surface-plasma source are described. H- ions are produced on the surface of a plasma grid covered by cesium and illuminated by fast plasma particles. The source uses a radio-frequency driver to generate plasma. A composite magnet system made of external permanent magnets confines and filters electrons in the plasma region, and deflects them in the extraction area. A multiaperture, multi-electrode ion optical system is used for beam formation. The electrode heating and cooling during long pulses is accomplished by circulating a heat transfer fluid through channels drilled in the electrodes bodies. H- ions extraction through a single aperture and 21 apertures was performed and studied. A stable H- beam with the current up to 0.7 A, energy up to 74 kV, and pulse duration up to 7 s was routinely obtained.

  2. The CPS Plasma Award at the Intel Science and Engineering Fair

    NASA Astrophysics Data System (ADS)

    Berry, Lee

    2012-10-01

    For the past eight years, the Coalition for Plasma Science (CPS) has presented an award for a plasma project at the Intel International Science and Engineering Fair (ISEF). We reported on the first five years of this award at the 2009 DPP Symposium. Pulsed neutron-producing experiments are a recurring topic, with the efforts now turning to applications. The most recent award at the Pittsburgh ISEF this past May was given for analysis of data from Brookhaven's Relativistic Heavy Ion Collider. The effort had the goal of understanding the fluid properties of the quark-gluon plasma. All of the CPS award-winning projects so far have been based on experiments, with four awards going to women students and four to men. In 2009 we noted that the number and quality of projects was improving. Since then, as we we predicted (hoped for), that trend has continued. The CPS looks forward to continuing its work with students who are excited about the possibilities of plasma. You too can share this excitement by judging at the 2013 fair in Phoenix on May 12-17. Information may be obtained by emailing cps@plasmacoalition.org.

  3. Development of super-clean diesel engine and combustor using nonthermal plasma hybrid aftertreatment

    NASA Astrophysics Data System (ADS)

    Okubo, Masaaki

    2015-10-01

    One of important and successful environmental applications of atmospheric-pressure corona discharge or plasma is electrostatic precipitator (ESP), which have been widely used for coal- or oil-fired boilers in electric power plants and particulate matter control emitted from industries such as glass melting furnace system, etc. In the ESPs, steady high voltage is usually applied to a pair of electrodes (at least, one of these has sharp edge). Unsteady pulsed high voltage is often applied for the collection of high-resistivity particulate matter (PM) to avoid reverse corona phenomena which reduce the collection efficiency of the ESPs. It was found that unsteady high voltage can treat hazardous gaseous components (NOx, SOx, hydrocarbon, and CO, etc.) in the exhaust gas, and researches were shifted from PM removal to hazardous gases aftertreatment with unsteady corona discharge induced plasmas. In the paper, recent results on diesel engine and industrial boiler emission controls are mainly reviewed among these our research topics.

  4. Probing the molecular structures of plasma-damaged and surface-repaired low-k dielectrics.

    PubMed

    Zhang, Xiaoxian; Myers, John N; Lin, Qinghuang; Bielefeld, Jeffery D; Chen, Zhan

    2015-10-21

    Fully understanding the effect and the molecular mechanisms of plasma damage and silylation repair on low dielectric constant (low-k) materials is essential to the design of low-k dielectrics with defined properties and the integration of low-k dielectrics into advanced interconnects of modern electronics. Here, analytical techniques including sum frequency generation vibrational spectroscopy (SFG), Fourier transform infrared spectroscopy (FTIR), contact angle goniometry (CA) and X-ray photoelectron spectroscopy (XPS) have been employed to provide a comprehensive characterization of the surface and bulk structure changes of poly(methyl)silsesquioxane (PMSQ) low-k thin films before and after O2 plasma treatment and silylation repair. O2 plasma treatment altered drastically both the molecular structures and water structures at the surfaces of the PMSQ film while no bulk structural change was detected. For example, ∼34% Si-CH3 groups were removed from the PMSQ surface, and the Si-CH3 groups at the film surface tilted toward the surface after the O2 plasma treatment. The oxidation by the O2 plasma made the PMSQ film surface more hydrophilic and thus enhanced the water adsorption at the film surface. Both strongly and weakly hydrogen bonded water were detected at the plasma-damaged film surface during exposure to water with the former being the dominate component. It is postulated that this enhancement of both chemisorbed and physisorbed water after the O2 plasma treatment leads to the degradation of low-k properties and reliability. The degradation of the PMSQ low-k film can be recovered by repairing the plasma-damaged surface using a silylation reaction. The silylation method, however, cannot fully recover the plasma induced damage at the PMSQ film surface as evidenced by the existence of hydrophilic groups, including C-O/C[double bond, length as m-dash]O and residual Si-OH groups. This work provides a molecular level picture on the surface structural changes of low

  5. Surface modification and stability of detonation nanodiamonds in microwave gas discharge plasma

    NASA Astrophysics Data System (ADS)

    Stanishevsky, Andrei V.; Walock, Michael J.; Catledge, Shane A.

    2015-12-01

    Detonation nanodiamonds (DND), with low hydrogen content, were exposed to microwave plasma generated in pure H2, N2, and O2 gases and their mixtures, and investigated using X-ray diffraction (XRD), Fourier Transform Infrared (FTIR), Raman, and X-ray photoelectron spectroscopies. Considerable alteration of the DND surface was observed under the plasma conditions for all used gases, but the diamond structure of the DND particle core was preserved in most cases. The stabilizing effect of H2 in H2/N2 and H2/O2 binary gas plasmas on the DND structure and the temperature-dependent formation of various CNHx surface groups in N2 and H2/N2 plasmas were observed and discussed for the first time. DND surface oxidation and etching were the main effects of O2 plasma, whereas the N2 plasma led to DND surfaces rich in amide groups below 1073 K and nitrile groups at higher temperatures. Noticeable graphitization of the DND core structure was detected only in N2 plasma when the substrate temperature was above 1103 K.

  6. Plasma sheet at lunar distance - Characteristics and interactions with the lunar surface

    NASA Technical Reports Server (NTRS)

    Rich, F. J.; Reasoner, D. L.; Burke, W. J.

    1973-01-01

    The plasma sheet at lunar distance is investigated with the use of data from the charged particle lunar environment experiment (CPLEE), complemented with data from the Explorer 35/ARC magnetometer. It is shown that the presence of the lunar surface does not appreciably affect measurements of the plasma sheet characteristics by the lunar-based CPLEE instrument. In particular, the lunar surface generally does not shadow plasma sheet particles. This may be due to rapid random passage (greater than 40 km/sec) of magnetotail field lines with respect to the lunar surface or to diffusion of plasma sheet electrons into the flux tubes in contact with the lunar surface. The plasma sheet is generally observed as a rapid increase in observed particle fluxes and a simultaneous decrease in field strength. A statistical analysis of the CPLEE data shows that the plasma sheet in the midnight sector has a thickness of 5 R sub E plus or minus 2 R sub E. Geomagnetic activity reduces the probability of encounters between the moon and the plasma sheet.

  7. Surface modifications of fusion reactor relevant materials on exposure to fusion grade plasma in plasma focus device

    NASA Astrophysics Data System (ADS)

    Niranjan, Ram; Rout, R. K.; Srivastava, R.; Chakravarthy, Y.; Mishra, P.; Kaushik, T. C.; Gupta, Satish C.

    2015-11-01

    An 11.5 kJ plasma focus (PF) device was used here to irradiate materials with fusion grade plasma. The surface modifications of different materials (W, Ni, stainless steel, Mo and Cu) were investigated using various available techniques. The prominent features observed through the scanning electron microscope on the sample surfaces were erosions, cracks, blisters and craters after irradiations. The surface roughness of the samples increased multifold after exposure as measured by the surface profilometer. The X-ray diffraction analysis indicated the changes in the microstructures and the structural phase transformation in surface layers of the samples. We observed change in volumes of austenite and ferrite phases in the stainless steel sample. The energy dispersive X-ray spectroscopic analysis suggested alloying of the surface layer of the samples with elements of the PF anode. We report here the comparative analysis of the surface damages of materials with different physical, thermal and mechanical properties. The investigations will be useful to understand the behavior of the perspective materials for future fusion reactors (either in pure form or in alloy) over the long operations.

  8. Evaluation Methodology for Surface Engineering Techniques to Improve Powertrain Efficiency in Military Vehicles

    DTIC Science & Technology

    2012-06-01

    The primary goal of the initial phase of evaluation is to experimentally measure the efficiency of gears and other tribological components with and...benefits of surface treatment to reciprocating mechanical components. 15. SUBJECT TERMS Surface engineering, gear efficiency, powertrain, tribology ...considered as a tribological system (gear surfaces, base oil, additives, surface chemistry, etc.) such that a change in one component may require

  9. Surface modification of polyester synthetic leather with tetramethylsilane by atmospheric pressure plasma

    NASA Astrophysics Data System (ADS)

    Kan, C. W.; Kwong, C. H.; Ng, S. P.

    2015-08-01

    Much works have been done on synthetic materials but scarcely on synthetic leather owing to its surface structures in terms of porosity and roughness. This paper examines the use of atmospheric pressure plasma (APP) treatment for improving the surface performance of polyester synthetic leather by use of a precursor, tetramethylsilane (TMS). Plasma deposition is regarded as an effective, simple and single-step method with low pollution. Scanning electron microscopy (SEM), X-ray photoelectron spectroscopy (XPS) and Fourier transform infrared spectroscopy (FTIR) confirm the deposition of organosilanes on the sample's surface. The results showed that under a particular combination of treatment parameters, a hydrophobic surface was achieved on the APP treated sample with sessile drop static contact angle of 138°. The hydrophobic surface is stable without hydrophilic recovery 30 days after plasma treatment.

  10. Impact of Plasma Surface Treatment on Bamboo Charcoal/silver Nanocomposite

    NASA Astrophysics Data System (ADS)

    Vignesh, K.; Vijayalakshmi, K. A.; Karthikeyan, N.

    2016-10-01

    Bamboo charcoal (BC) accompanied silver (Ag) nanocomposite is synthesized through sol-gel method. The produced BC/Ag nanocomposite was surface modified by air and oxygen plasma treatments. Silver ions (Ag+) will serve to improve the antibacterial activity as well as the surface area of BC. Plasma treatment has improved the surface functional groups, crystalline intensity and antibacterial activity of the prepared nanocomposite. Scanning electron microscopy (SEM) and X-ray diffraction (XRD) studies show that Ag nanoparticles have good agreement with BC and the particle size has a mean diameter of 20-40nm. We observe the carboxyl functional groups in Fourier transform infrared spectroscopy (FTIR) after the oxygen plasma treatment. Moreover surface area and adsorption were analyzed by using the Brunauer, Emmett and Teller (BET) surface area (SBET) and UV-Vis spectroscopy.

  11. Protein immobilization capacity and covalent binding coverage of pulsed plasma polymer surfaces

    NASA Astrophysics Data System (ADS)

    Yin, Yongbai; Bax, Daniel; McKenzie, David R.; Bilek, Marcela M. M.

    2010-06-01

    Three carbon surfaces were deposited using pulsed plasma enhanced chemical vapour deposition method: a low and a high nitrogen-containing plasma polymer surfaces and a diamond-like carbon surface. The surfaces were analysed using both X-ray photoelectron spectroscopy (XPS) technique and the enzyme-linked immunosorbent assay (ELISA) method combining with sodium dodecyl sulphate (SDS) cleaning to investigate the capacity and covalent binding of the immobilized proteins. A good correlation was found on quantification of remaining protein after SDS cleaning using the ELISA method and the XPS technique. All surfaces had similar initial capacity of protein attachment but with large different resistance to SDS cleaning. The analysis showed that the high nitrogen-containing plasma polymer was the best biocompatible material due to its highest resistance to SDS cleaning, i.e. with the highest quantity (˜80%) of proteins bound covalently.

  12. Suppression of surface crystallization on borosilicate glass using RF plasma treatment

    NASA Astrophysics Data System (ADS)

    Yoo, Sunghyun; Ji, Chang-Hyeon; Jin, Joo-Young; Kim, Yong-Kweon

    2014-10-01

    Surface crystallization on a commercial grade borosilicate glass wafer, Borofloat® 33, is effectively prevented against 3 h of thermal reflow process at 850 °C. Surface plasma treatment with three different reactive gases, CF4, SF6, and Cl2, has been performed prior to the annealing. The effect of plasma treatment on surface ion concentration and nucleation of cristobalite were examined through optical microscope and x-ray photoemission spectroscopy. The dominant cause that suppresses crystallization was verified to be the increase of surface ion concentration of alumina during the plasma treatment. Both CF4 and SF6 treatment of no less than 30 s showed significant efficacy in suppressing crystallization by a factor of more than 112. Average surface roughness and the optical transparency were also enhanced by a factor of 15 and 3, respectively, compared to untreated sample.

  13. Electric propulsion. [pulsed plasma thruster and electron bombardment ion engine for MSAT attitude control and stationkeeping

    NASA Technical Reports Server (NTRS)

    1982-01-01

    An alternative propulsion subsystem for MSAT is presented which has a potential of reducing the satellite weight by more than 15%. The characteristics of pulsed plasma and ion engines are described and used to estimate of the mass of the propellant and thrusters for attitude control and stationkeeping functions for MSAT. Preliminary estimates indicate that the electric propulsion systems could also replace the large momentum wheels necessary to counteract the solar pressure; however, the fine pointing wheels would be retained. Estimates also show that either electric propulsion system can save approximately 18% to 20% of the initial 4,000 kg mass. The issues that require further experimentation are mentioned.

  14. Surface composition XPS analysis of a plasma treated polystyrene: Evolution over long storage periods.

    PubMed

    Ba, Ousmane M; Marmey, Pascal; Anselme, Karine; Duncan, Anthony C; Ponche, Arnaud

    2016-09-01

    A polystyrene surface (PS) was initially treated by cold nitrogen and oxygen plasma in order to incorporate in particular amine and hydroxyl functions, respectively. The evolution of the chemical nature of the surface was further monitored over a long time period (580 days) by chemical assay, XPS and contact angle measurements. Surface density quantification of primary amine groups was performed using three chemical amine assays: 4-nitrobenzaldehyde (4-NBZ), Sulfo succinimidyl 6-[3'(2 pyridyldithio)-pionamido] hexanoate (Sulfo-LC-SPDP) and iminothiolane (ITL). The results showed amine densities were in the range of 2 per square nanometer (comparable to the results described in the literature) after 5min of nitrogen plasma treatment. Over the time period investigated, chemical assays, XPS and contact angles suggest a drastic significant evolution of the chemical nature of the surface within the first two weeks. Beyond that time period and up to almost two years, nitrogen plasma modified substrates exhibits a slow and continuous oxidation whereas oxygen plasma modifed polystyrene surface is chemically stable after two weeks of storage. The latter appeared to "ease of" showing relatively mild changes within the one year period. Our results suggest that it may be preferable to wait for a chemical "stabilization" period of two weeks before subsequent covalent immobilization of proteins onto the surface. The originality of this work resides in the study of the plasma treated surface chemistry evolution over long periods of storage time (580 days) considerably exceeding those described in the literature.

  15. Influence of water/O₂ plasma treatment on cellular responses of PCL and PET surfaces.

    PubMed

    Türkoğlu Şaşmazel, Hilal; Aday, Sezin; Manolache, Sorin; Gümüşderelioğlu, Menemşe

    2011-01-01

    In this study, low pressure water/O₂ plasma treatment was performed in order to obtain COOH functionalities on the surface of poly-ε-caprolactone (PCL) membranes as well as non-woven polyester fabric (NWPF) discs. The plasma treatments were performed in a cylindrical, capacitively coupled RF-plasma-reactor and then following steps were performed: in situ (oxalyl chloride vapors) gas/solid reaction to convert -OH functionalities into -COCl groups; and hydrolysis under open laboratory conditions using air moisture for final-COOH functionalities. COOH and OH functionalities on modified surfaces were detected quantitatively by using fluorescent labeling technique and an UVX 300G sensor. Electron spectroscopy for chemical analysis (ESCA) was used to evaluate the relative surface atomic compositions and the carbon and oxygen linkages located in non-equivalent atomic positions of untreated and modified surfaces. Atomic force microscope (AFM) analysis showed that nanoscale features of the PCL surfaces are dramatically changed during the surface treatments. Scanning electron microscopy (SEM) results indicated the changes in the relatively smooth appearance of the untreated NWPF discs after the plasma treatment. Periodontal ligament (PDL) fibroblasts were used in cell culture studies. Cell culture results showed that plasma treated PCL membranes and NWPF discs were favorable for the PDL cell spreading, growth and viability due to the presence of functional groups and/or nanotopographies on their surfaces.

  16. Plasma-enhanced synthesis of bactericidal quaternary ammonium thin layers on stainless steel and cellulose surfaces.

    PubMed

    Jampala, Soujanya N; Sarmadi, M; Somers, E B; Wong, A C L; Denes, F S

    2008-08-19

    We have investigated bottom-up chemical synthesis of quaternary ammonium (QA) groups exhibiting antibacterial properties on stainless steel (SS) and filter paper surfaces via nonequilibrium, low-pressure plasma-enhanced functionalization. Ethylenediamine (ED) plasma under suitable conditions generated films rich in secondary and tertiary amines. These functional structures were covalently attached to the SS surface by treating SS with O 2 and hexamethyldisiloxane plasma prior to ED plasma treatment. QA structures were formed by reaction of the plasma-deposited amines with hexyl bromide and subsequently with methyl iodide. Structural compositions were examined by electron spectroscopy for chemical analysis and Fourier transform infrared spectroscopy, and surface topography was investigated with atomic force microscopy and water contact angle measurements. Modified SS surfaces exhibited greater than a 99.9% decrease in Staphylococcus aureus counts and 98% in the case of Klebsiella pneumoniae. The porous filter paper surfaces with immobilized QA groups inactivated 98.7% and 96.8% of S. aureus and K. pneumoniae, respectively. This technique will open up a novel way for the synthesis of stable and very efficient bactericidal surfaces with potential applications in development of advanced medical devices and implants with antimicrobial surfaces.

  17. Dependence of Lunar Surface Charging on Solar Wind Plasma Conditions and Solar Irradiation

    NASA Technical Reports Server (NTRS)

    Stubbs, T. J.; Farrell, W. M.; Halekas, J. S.; Burchill, J. K.; Collier, M. R.; Zimmerman, M. I.; Vondrak, R. R.; Delory, G. T.; Pfaff, R. F.

    2014-01-01

    The surface of the Moon is electrically charged by exposure to solar radiation on its dayside, as well as by the continuous flux of charged particles from the various plasma environments that surround it. An electric potential develops between the lunar surface and ambient plasma, which manifests itself in a near-surface plasma sheath with a scale height of order the Debye length. This study investigates surface charging on the lunar dayside and near-terminator regions in the solar wind, for which the dominant current sources are usually from the pohotoemission of electrons, J(sub p), and the collection of plasma electrons J(sub e) and ions J(sub i). These currents are dependent on the following six parameters: plasma concentration n(sub 0), electron temperature T(sub e), ion temperature T(sub i), bulk flow velocity V, photoemission current at normal incidence J(sub P0), and photo electron temperature T(sub p). Using a numerical model, derived from a set of eleven basic assumptions, the influence of these six parameters on surface charging - characterized by the equilibrium surface potential, Debye length, and surface electric field - is investigated as a function of solar zenith angle. Overall, T(sub e) is the most important parameter, especially near the terminator, while J(sub P0) and T(sub p) dominate over most of the dayside.

  18. Surface modification of chromatography adsorbents by low temperature low pressure plasma.

    PubMed

    Arpanaei, A; Winther-Jensen, B; Theodosiou, E; Kingshott, P; Hobley, T J; Thomas, O R T

    2010-10-29

    In this study we show how low temperature glow discharge plasma can be used to prepare bi-layered chromatography adsorbents with non-adsorptive exteriors. The commercial strong anion exchange expanded bed chromatography matrix, Q HyperZ, was treated with plasmas in one of two general ways. Using a purpose-designed rotating reactor, plasmas were employed to either: (i) remove anion exchange ligands at or close to the exterior surface of Q HyperZ, and replace them with polar oxygen containing functions ('plasma etching and oxidation'); or (ii) bury the same surface exposed ligands beneath thin polymer coatings ('plasma polymerization coating') using appropriate monomers (vinyl acetate, vinyl pyrrolidone, safrole) and argon as the carrier gas. X-ray photoelectron spectroscopy analysis (first ∼10 nm depth) of Q HyperZ before and after the various plasma treatments confirmed that substantial changes to the elemental composition of Q HyperZ's exterior had been inflicted in all cases. The atomic percent changes in carbon, nitrogen, oxygen, yttrium and zirconium observed after being exposed to air plasma etching were entirely consistent with: the removal of pendant Q (trimethylammonium) functions; increased exposure of the underlying yttrium-stabilised zirconia shell; and introduction of hydroxyl and carbonyl functions. Following plasma polymerization treatments (with all three monomers tested), the increased atomic percent levels of carbon and parallel drops in nitrogen, yttrium and zirconium provided clear evidence that thin polymer coats had been created at the exteriors of Q HyperZ adsorbent particles. No changes in adsorbent size and surface morphology, nor any evidence of plasma-induced damage could be discerned from scanning electron micrographs, light micrographs and measurements of particle size distributions following 3 h exposure to air (220 V; 35.8 W L(-1)) or 'vinyl acetate/argon' (170 V; 16.5 W L(-1)) plasmas. Losses in bulk chloride exchange capacity

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

    NASA Astrophysics Data System (ADS)

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

    2015-09-01

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

  20. The DIPSI (Direct Implicit Plasma Surface Interactions) computer code user's manual

    SciTech Connect

    Procassini, R.J. . Dept. of Nuclear Engineering); Cohen, B.I. )

    1990-06-01

    DIPSI (Direct Implicit Plasma Surface Interactions) is a one-dimensional, bounded particle-in-cell (PIC) simulation code designed to investigate the interaction of plasma with a solid surface, such as a limiter or divertor plate in a tokamak fusion device. Plasma confinement and transport may be studied in a system which includes an applied magnetic field (oriented normal to the solid surface) and/or a self-consistent electrostatic potential. The PIC code DIPSI is an offshoot of the PIC code TESS (Tandem Experiment Simulation Studies) which was developed to study plasma confinement in mirror devices. The codes DIPSI and TESS are direct descendants of the PIC code ES1 that was created by A. B. Langdon. This document provides the user with a brief description of the methods used in the code and a tutorial on the use of the code. 11 refs., 2 tabs.

  1. Investigations of the surface activation of thermoplastic polymers by atmospheric pressure plasma treatment with a stationary plasma jet

    NASA Astrophysics Data System (ADS)

    Moritzer, Elmar; Nordmeyer, Timo; Leister, Christian; Schmidt, Martin Andreas; Grishin, Artur; Knospe, Alexander

    2016-03-01

    The production of high-quality thermoplastic parts often requires an additional process step after the injection molding stage. This may be a coating, bonding process or a 2K-injection moulding process. A commonly used process to improve the bond strength is atmospheric pressure plasma treatment. A variety of applications are realized with the aid of CNC systems. Although they ensure excellent reproducibility, they make it difficult to implement inline applications. This paper therefore examines the possibility of surface treatment using a stationary plasma jet. However, before it is possible to integrate this technology into a production process, preliminary trials need to be carried out to establish which factors influence the process. Experimental tests were performed using a special test set-up, enabling geometric, plasma-specific parameters to be identified. These results can help with the practical integration of this technology into existing production processes.

  2. A in Situ Study of Plasma Etching Surface Chemistry Using Reflection Infrared Spectroscopy

    NASA Astrophysics Data System (ADS)

    Lucchesi, Robert Peter

    Plasma etching is an important process in semiconductor manufacturing. The present work describes a means by which plasma etching surface chemistry may be studied in situ. The systems of interest were the sulfur hexafluoride plasma etching of silicon and tungsten in a diode reactor. A reflection infrared spectrometer was designed and constructed to be able to scan the frequency region from about 550cm ^{-1} to 1300cm ^{-1}, and a plasma etch reactor was modified to allow access to the infrared beam. Reflection infrared spectroscopy (RIS) allows the measurement of light absorbed by molecules adsorbed on a reflective surface selectively from light absorbed by molecules in the gas phase. RIS applied to heavily doped silicon substrates had limited success. While sulfur fluorine species were detected on the surface during plasma etching, no silicon fluorine species were ever detected. The sulfur fluorine species (referred to as SF_{rm x}) were not seen under any circumstances in the absence of an SF_6 plasma. Severe baseline drift of the infrared spectrometer during plasma etching was the main reason for the limited success. However, the results were significant in that they demonstrated the presence of sulfur fluorine species during the plasma etching of silicon in an SF_6 plasma. The baseline drift problems experienced with silicon were not found when tungsten was studied. The same SF _{rm x} feature detected on silicon was also found on tungsten during etching in an SF_6 plasma, but was never seen in the absence of the plasma. A detailed experimental and theoretical study was performed to show that the surface absorption feature seen was actually due to SF _{rm x} adsorbed on the surface. A hysteresis behavior was observed in the SF_ {rm x} concentration as the plasma power was ramped up and subsequently decreased. Finally, it could not be concluded if SF_{rm x} participated in the etch reaction by fluorinating the tungsten surface, but the presence of SF_ {rm x} on

  3. Creation of hydrophilic nitric oxide releasing polymers via plasma surface modification.

    PubMed

    Pegalajar-Jurado, A; Joslin, J M; Hawker, M J; Reynolds, M M; Fisher, E R

    2014-08-13

    Herein, we describe the surface modification of an S-nitrosated polymer derivative via H2O plasma treatment, resulting in polymer coatings that maintained their nitric oxide (NO) releasing capabilities, but exhibited dramatic changes in surface wettability. The poly(lactic-co-glycolic acid)-based hydrophobic polymer was nitrosated to achieve a material capable of releasing the therapeutic agent NO. The NO-loaded films were subjected to low-temperature H2O plasma treatments, where the treatment power (20-50 W) and time (1-5 min) were varied. The plasma treated polymer films were superhydrophilic (water droplet spread completely in <100 ms), yet retained 90% of their initial S-nitrosothiol content. Under thermal conditions, NO release profiles were identical to controls. Under buffer soak conditions, the NO release profile was slightly lowered for the plasma-treated materials; however, they still result in physiologically relevant NO fluxes. XPS, SEM-EDS, and ATR-IR characterization suggests the plasma treatment resulted in polymer rearrangement and implantation of hydroxyl and carbonyl functional groups. Plasma treated samples maintained both hydrophilic surface properties and NO release profiles after storage at -18 °C for at least 10 days, demonstrating the surface modification and NO release capabilities are stable over time. The ability to tune polymer surface properties while maintaining bulk properties and NO release properties, and the stability of those properties under refrigerated conditions, represents a unique approach toward creating enhanced therapeutic biopolymers.

  4. Surface composition, chemistry, and structure of polystyrene modified by electron-beam-generated plasma.

    PubMed

    Lock, Evgeniya H; Petrovykh, Dmitri Y; Mack, Paul; Carney, Tim; White, Richard G; Walton, Scott G; Fernsler, Richard F

    2010-06-01

    Polystyrene (PS) surfaces were treated by electron-beam-generated plasmas in argon/oxygen, argon/nitrogen, and argon/sulfur hexafluoride environments. The resulting modifications of the polymer surface energy, morphology, and chemical composition were analyzed by a suite of complementary analytical techniques: contact angle goniometry, atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS), and reflection electron energy loss spectroscopy (REELS). The plasma treatments produced only minimal increases in the surface roughness while introducing the expected chemical modifications: oxygen-based after Ar/O(2) plasma, oxygen- and nitrogen-based after Ar/N(2) plasma, and fluorine-based after Ar/SF(6) plasma. Fluorinated PS surfaces became hydrophobic and did not significantly change their properties over time. In contrast, polymer treated in Ar/O(2) and Ar/N(2) plasmas initially became hydrophilic but underwent hydrophobic recovery after 28 days of aging. The aromatic carbon chemistry in the top 1 nm of these aged surfaces clearly indicated that the hydrophobic recovery was produced by reorientation/diffusion of undamaged aromatic polymer fragments from the bulk rather than by contamination. Nondestructive depth profiles of aged plasma-treated PS films were reconstructed from parallel angle-resolved XPS (ARXPS) measurements using a maximum-entropy algorithm. The salient features of reconstructed profiles were confirmed by sputter profiles obtained with 200 eV Ar ions. Both types of depth profiles showed that the electron-beam-generated plasma modifications are confined to the topmost 3-4 nm of the polymer surface, while valence band measurements and unsaturated carbon signatures in ARXPS and REELS data indicated that much of the PS structure was preserved below 9 nm.

  5. In situ plasma removal of surface contaminants from ion trap electrodes

    SciTech Connect

    Haltli, Raymond A.

    2015-05-01

    In this thesis, the construction and implementation of an in situ plasma discharge designed to remove surface contaminants from electrodes in an ion trapping experimental system is presented with results. In recent years, many advances have been made in using ion traps for quantum information processing. All of the criteria defined by DiVincenzo for using ion traps for implementing a quantum computer have been individually demonstrated, and in particular surface traps provide a scalable platform for ions. In order to be used for quantum algorithms, trapped ions need to be cooled to their motional (quantum mechanical) ground state. One of the hurdles in integrating surface ion traps for a quantum computer is minimizing electric field noise, which causes the ion to heat out of its motional ground state and which increases with smaller ion-to-electrode distances realized with surface traps. Surface contamination of trap electrodes is speculated to be the primary source of electric field noise. The main goal achieved by this work was to implement an in situ surface cleaning solution for surface electrode ion traps, which would not modify the ion trap electrode surface metal. Care was taken in applying the RF power in order to localize a plasma near the trap electrodes. A method for characterizing the energy of the plasma ions arriving at the ion trap surface is presented and results for plasma ion energies are shown. Finally, a method for quantifying the effectiveness of plasma cleaning of trap electrodes, using the surface analysis technique of X-ray photoelectron spectroscopy for measuring the amount and kind of surface contaminants, is described. A significant advantage of the trap electrode surface cleaning method presented here is the minimal changes necessary for implementation on a working ion trap experimental system.

  6. Non-uniform Erosion and Surface Evolution of Plasma-Facing Materials for Electric Propulsion

    NASA Astrophysics Data System (ADS)

    Matthes, Christopher Stanley Rutter

    A study regarding the surface evolution of plasma-facing materials is presented. Experimental efforts were performed in the UCLA Pi Facility, designed to explore the physics of plasma-surface interactions. The influence of micro-architectured surfaces on the effects of plasma sputtering is compared with the response of planar samples. Ballistic deposition of sputtered atoms as a result of geometric re-trapping is observed. This provides a self-healing mechanism of micro-architectured surfaces during plasma exposure. This result is quantified using a QCM to demonstrate the evolution of surface features and the corresponding influence on the instantaneous sputtering yield. The sputtering yield of textured molybdenum samples exposed to 300 eV Ar plasma is found to be roughly 1 of the 2 corresponding value of flat samples, and increases with ion fluence. Mo samples exhibited a sputtering yield initially as low as 0.22+/-8%, converging to 0.4+/-8% at high fluence. Although the yield is dependent on the initial surface structure, it is shown to be transient, reaching a steady-state value that is independent of initial surface conditions. A continuum model of surface evolution resulting from sputtering, deposition and surface diffusion is also derived to resemble the damped Kuramoto-Sivashinsky (KS) equation of non-linear dynamics. Linear stability analysis of the evolution equation provides an estimate of the selected wavelength, and its dependence on the ion energy and angle of incidence. The analytical results are confirmed by numerical simulations of the equation with a Fast Fourier Transform method. It is shown that for an initially flat surface, small perturbations lead to the evolution of a selected surface pattern that has nano- scale wavelength. When the surface is initially patterned by other means, the final resulting pattern is a competition between the "templated" pattern and the "self-organized" structure. Potential future routes of research are also

  7. Surface morphology of tungsten exposed to helium plasma at temperatures below fuzz formation threshold 1073 K

    NASA Astrophysics Data System (ADS)

    Sakamoto, Ryuichi; Bernard, Elodie; Kreter, Arkadi; Yoshida, Naoaki

    2017-01-01

    Impact of crystal orientation on the surface morphology of the helium plasma exposed tungsten has been investigated on the linear device PSI-2. A nanoscale undulating surface structure having a periodic arrangement is formed for temperatures below 1073 K, in contrast to the fuzz nanostructure formation in a higher temperature range. The crests of undulation align with the < 1 0 0> direction. The interval of the undulation is narrowest at the crystal grain of {1 1 0} surface. The interval becomes wider as the crystal grain surface tilts away from the {1 1 0} surface, and the undulating surface structure is not formed near the {1 0 0} surface. The height of undulations is ∼ 8 nm, independently of the interval of the undulations, and it corresponds to the depth of the layer heavily damaged due to helium plasma exposure.

  8. Effects of piston surface treatments on performance and emissions of a methanol-fueled, direct injection, stratified charge engine

    NASA Astrophysics Data System (ADS)

    West, B.; Green, J. B.

    1994-07-01

    The purpose of this study was to investigate the effects of thermal barrier coatings and/or surface treatments on the performance and emissions of a methanol-fueled, direct-injection, stratified-charge (DISC) engine. A Ricardo Hydra Mark III engine was used for this work and in previous experiments at Oak Ridge National Laboratory (ORNL). The primary focus of the study was to examine the effects of various piston insert surface treatments on hydrocarbon (HC) and oxides of nitrogen (NO(x)) emissions. Previous studies have shown that engines of this class have a tendency to perform poorly at low loads and have high unburned fuel emissions. A blank aluminum piston was modified to employ removable piston bowl inserts. Four different inserts were tested in the experiment: aluminum, stainless steel with a 1.27-mm (0.050-in.) air gap (to act as a thermal barrier), and two stainless steel/air-gap inserts with coatings. Two stainless steel inserts were dimensionally modified to account for the coating thickness (1.27-mm) and coated identically with partially stabilized zirconia (PSZ). One of the coated inserts then had an additional seal-coat applied. The coated inserts were otherwise identical to the stainless steel/air-gap insert (i.e., they employed the same 1.27-mm air gap). Thermal barrier coatings were employed in an attempt to increase combustion chamber surface temperatures, thereby reducing wall quenching and promoting more complete combustion of the fuel in the quench zone. The seal-coat was applied to the zirconia to reduce the surface porosity; previous research suggested that despite the possibly higher surface temperatures obtainable with a ceramic coating, the high surface area of a plasma-sprayed coating may actually allow fuel to adhere to the surface and increase the unburned fuel emissions and fuel consumption.

  9. Multi-surface topography targeted plateau honing for the processing of cylinder liner surfaces of automotive engines

    NASA Astrophysics Data System (ADS)

    Lawrence, K. Deepak; Ramamoorthy, B.

    2016-03-01

    Cylinder bores of automotive engines are 'engineered' surfaces that are processed using multi-stage honing process to generate multiple layers of micro geometry for meeting the different functional requirements of the piston assembly system. The final processed surfaces should comply with several surface topographic specifications that are relevant for the good tribological performance of the engine. Selection of the process parameters in three stages of honing to obtain multiple surface topographic characteristics simultaneously within the specification tolerance is an important module of the process planning and is often posed as a challenging task for the process engineers. This paper presents a strategy by combining the robust process design and gray-relational analysis to evolve the operating levels of honing process parameters in rough, finish and plateau honing stages targeting to meet multiple surface topographic specifications on the final running surface of the cylinder bores. Honing experiments were conducted in three stages namely rough, finish and plateau honing on cast iron cylinder liners by varying four honing process parameters such as rotational speed, oscillatory speed, pressure and honing time. Abbott-Firestone curve based functional parameters (Rk, Rpk, Rvk, Mr1 and Mr2) coupled with mean roughness depth (Rz, DIN/ISO) and honing angle were measured and identified as the surface quality performance targets to be achieved. The experimental results have shown that the proposed approach is effective to generate cylinder liner surface that would simultaneously meet the explicit surface topographic specifications currently practiced by the industry.

  10. Elimination of diazinon insecticide from cucumber surface by atmospheric pressure air-dielectric barrier discharge plasma.

    PubMed

    Dorraki, Naghme; Mahdavi, Vahideh; Ghomi, Hamid; Ghasempour, Alireza

    2016-12-06

    The food industry is in a constant search for new technologies to improve the commercial sterilization process of agricultural commodities. Plasma treatment may offer a novel and efficient method for pesticide removal from agricultural product surfaces. To study the proposed technique of plasma food treatment, the degradation behavior of diazinon insecticide by air-dielectric barrier discharge (DBD) plasma was investigated. The authors studied the effect of different plasma powers and treatment times on pesticide concentration in liquid form and coated on the surface of cucumbers, where the diazinon residue was analyzed with mass spectroscopy gas chromatography. Our results suggest that atmospheric pressure air-DBD plasma is potentially effective for the degradation of diazinon insecticide, and mainly depends on related operating parameters, including plasma treatment time, discharge power, and pesticide concentrations. Based on the interaction between reactive oxygen species and electrons in the plasma with the diazinon molecule, two degradation pathway of diazinon during plasma treatment are proposed. It was also found that produced organophosphate pesticides are harmless and less hazardous compounds than diazinon.

  11. Optical Diagnostics of Air Flows Induced in Surface Dielectric Barrier Discharge Plasma Actuator

    NASA Astrophysics Data System (ADS)

    Kobatake, Takuya; Deguchi, Masanori; Suzuki, Junya; Eriguchi, Koji; Ono, Kouichi

    2014-10-01

    A surface dielectric barrier discharge (SDBD) plasma actuator has recently been intensively studied for the flow control over airfoils and turbine blades in the fields of aerospace and aeromechanics. It consists of two electrodes placed on both sides of the dielectric, where one is a top powered electrode exposed to the air, and the other is a bottom grounded electrode encapsulated with an insulator. The unidirectional gas flow along the dielectric surfaces is induced by the electrohydrodynamic (EHD) body force. It is known that the thinner the exposed electrode, the greater the momentum transfer to the air is, indicating that the thickness of the plasma is important. To analyze plasma profiles and air flows induced in the SDBD plasma actuator, we performed time-resolved and -integrated optical emission and schlieren imaging of the side view of the SDBD plasma actuator in atmospheric air. We applied a high voltage bipolar pulse (4-8 kV, 1-10 kHz) between electrodes. Experimental results indicated that the spatial extent of the plasma is much smaller than that of the induced flows. Experimental results further indicated that in the positive-going phase, a thin and long plasma is generated, where the optical emission is weak and uniform; on the other hand, in the negative-going phase, a thick and short plasma is generated, where a strong optical emission is observed near the top electrode.

  12. Effects of oxygen plasma treatment on the surface wettability and dissolution of furosemide compacts.

    PubMed

    Naseem, A; Olliff, C J; Martini, L G; Lloyd, A W

    2003-11-01

    The plasma irradiation of furosemide (frusemide) was investigated as a possible technique for increasing the dissolution rate of this drug. Oxygen plasma was used to generate oxygen-containing functional groups on the surface of the compact to increase the wettability of the surface and the dissolution rate of the drug. Compacts of furosemide (300 mg) were produced using a stainless steel die and punch assembly, which was placed into a KBr press. The time of the plasma treatment was varied to assess the effect if any upon the dissolution rate and the wettability of the drug. Dissolution experiments of the plasma-treated and untreated compacts were carried out using the paddle apparatus method. Dissolution was carried out at 37 degrees C using 1 L of 0.1 M HCl and phosphate buffer (pH 6). The wettability was assessed by contact angle measurements using the sessile drop technique. Untreated and plasma-treated samples were analysed by scanning electron microscopy at x 5000 magnification. Plasma treatment was found to lower the equilibrium contact angle from approximately 50 to 35 degrees but the dissolution rate was not significantly affected. This was attributed to fusion of the surface by the plasma treatment.

  13. Adsorption kinetics of organophosphonic acids on plasma-modified oxide-covered aluminum surfaces.

    PubMed

    Giza, M; Thissen, P; Grundmeier, G

    2008-08-19

    Tailoring of oxide chemistry on aluminum by means of low-pressure water and argon plasma surface modification was performed to influence the kinetics of the self-assembly process of octadecylphosphonic acid monolayers. The plasma-induced surface chemistry was studied by in situ FTIR reflection-absorption spectroscopy (IRRAS). Ex situ IRRAS and X-ray photoelectron spectroscopy were applied for the analysis of the adsorbed self-assembled monolayers. The plasma-induced variation of the hydroxide to oxide ratio led to different adsorption kinetics of the phosphonic acid from dilute ethanol solutions as measured by means of a quartz crystal microbalance. Water plasma treatment caused a significant increase in the density of surface hydroxyl groups in comparison to that of the argon-plasma-treated surface. The hydroxyl-rich surface led to significantly accelerated adsorption kinetics of the phosphonic acid with a time of monolayer formation of less than 1 min. On the contrary, decreasing the surface hydroxyl density slowed the adsorption kinetics.

  14. Effect of Surface Impulsive Thermal Loads on Fatigue Behavior of Constant Volume Propulsion Engine Combustor Materials

    NASA Technical Reports Server (NTRS)

    Zhu, Dongming; Fox, Dennis S.; Miller, Robert A.; Ghosn, Louis J.; Kalluri, Sreeramesh

    2004-01-01

    The development of advanced high performance constant-volume-combustion-cycle engines (CVCCE) requires robust design of the engine components that are capable of enduring harsh combustion environments under high frequency thermal and mechanical fatigue conditions. In this study, a simulated engine test rig has been established to evaluate thermal fatigue behavior of a candidate engine combustor material, Haynes 188, under superimposed CO2 laser surface impulsive thermal loads (30 to 100 Hz) in conjunction with the mechanical fatigue loads (10 Hz). The mechanical high cycle fatigue (HCF) testing of some laser pre-exposed specimens has also been conducted under a frequency of 100 Hz to determine the laser surface damage effect. The test results have indicated that material surface oxidation and creep-enhanced fatigue is an important mechanism for the surface crack initiation and propagation under the simulated CVCCE engine conditions.

  15. Dust Rotation Effects on DIA Surface Waves in a Semi-bounded Lorentzian Plasma

    SciTech Connect

    Lee, Myoung-Jae

    2008-09-07

    The dispersion relation for a dust ion-acoustic (DIA) surface wave is kinetically derived for the semi-bounded Lorentzian plasma containing elongated and rotating charged dust particles. The DIA surface wave frequency is found to be decreased as the dust rotational frequency increases.

  16. Plasma surface modification as a new approach to protect urinary catheter against Escherichia coli biofilm formation

    PubMed Central

    Taheran, Leila; Zarrini, Gholamreza; Khorram, Sirous; Zakerhamidi, Mohammad Sadegh

    2016-01-01

    Background and Objectives: Biomaterials are widely used in medical devices such as urinary catheters. One of the main problems associated with long term using of the urinary catheters is biofilm formation on their surfaces. Many techniques have been presented to reduce the biofilm formation. One of the most revolutionary techniques allowing such surface fictionalization is plasma surface modification. Materials and Methods: In this study, a glow discharge plasma (GDP) effect on Escherichia coli biofilm formation on the surface of urinary catheter in the pressure of 1.6 × 10−1 Torr of nitrogen, discharge voltage about 1.2 kV and current of 150 mA for 20 minutes has been investigated. Crystal violet binding assay and sonication method were performed in order to evaluate the amount of biofilm formation on tested biomaterials. Results: Characterization of modified surfaces by Attenuated Total Reflectance Fourier Transform Infrared Spectrometry (ATR-FTIR) and atomic force microscopy (AFM) revealed a noticeable change in hydrophobicity and roughness of catheter surfaces achieved by nitrogen plasma. The results of crystal violet binding assay and sonication method showed that the amount of biofilm formation on modified surface was about 86% less than the pristine sample. Conclusion: Plasma surface modification can reduce the risk of infections in patients with long-term use of urinary catheters. PMID:28210465

  17. Microwave and plasma-assisted modification of composite fiber surface topography

    DOEpatents

    Paulauskas, Felix L [Knoxville, TN; White, Terry L [Knoxville, TN; Bigelow, Timothy S [Knoxville, TN

    2003-02-04

    The present invention introduces a novel method for producing an undulated surface on composite fibers using plasma technology and microwave radiation. The undulated surface improves the mechanical interlocking of the fibers to composite resins and enhances the mechanical strength and interfacial sheer strength of the composites in which they are introduced.

  18. Effects of Surface Wave Turbulence on the Steep Density Gradients in Laser-Produced Plasmas

    NASA Astrophysics Data System (ADS)

    Gradov, O. M.; Stenflo, L.

    1984-01-01

    We point out that the surface wave turbulence in the plasma region where the temperature and density have large gradients can reduce the thermal flux and consequently steepen the temperature and density profiles significantly. An expression for the resultant density gradient as a function of the stationary intensity of the excited surface modes is also calculated.

  19. Surface electronic states of low-temperature H-plasma-exposed Ge(100)

    NASA Astrophysics Data System (ADS)

    Cho, Jaewon; Nemanich, R. J.

    1992-11-01

    The surface of low-temperature H-plasma-cleaned Ge(100) was studied by angle-resolved UV-photoemission spectroscopy and low-energy electron diffraction (LEED). The surface was prepared by an ex situ preclean followed by an in situ H-plasma exposure at a substrate temperature of 150-300 °C. Auger-electron spectroscopy indicated that the in situ H-plasma clean removed the surface contaminants (carbon and oxygen) from the Ge(100) surface. The LEED pattern varied from a 1×1 to a sharp 2×1, as the substrate temperature was increased. The H-induced surface state was identified at ~5.6 eV below EF, which was believed to be mainly due to the ordered or disordered monohydride phases. The annealing dependence of the spectra showed that the hydride started to dissociate at a temperature of 190 °C, and the dangling-bond surface state was identified. A spectral shift upon annealing indicated that the H-terminated surfaces were unpinned. After the H-plasma clean at 300 °C the dangling-bond surface state was also observed directly with no evidence of H-induced states.

  20. Double Glow Plasma Surface Alloying Antibacterial Silver Coating on Pure Titanium

    NASA Astrophysics Data System (ADS)

    Lin, Naiming; Guo, Junwen; Hang, Ruiqiang; Zou, Jiaojuan; Tang, Bin

    2014-03-01

    In order to endow the commercial pure titanium dental implant material with antibacterial property and aimed at avoiding the invalidation that is caused by bacterial adhesion on the surface, a silver coating was fabricated via double glow plasma surface alloying. The antibacterial property of the silver coating was assessed via in vitro estimation. The results showed that a continuous and compact coating was formed. The silver coating had absolute superiority in antibacterial property to raw commercial pure titanium. Double glow plasma surface alloying with silver on commercial pure titanium dental implant material could be considered as a potentially effective method for preventing bacterial adhesion.

  1. Double Glow Plasma Surface Alloying Antibacterial Silver Coating on Pure Titanium

    NASA Astrophysics Data System (ADS)

    Lin, Naiming; Guo, Junwen; Hang, Ruiqiang; Zou, Jiaojuan; Tang, Bin

    2014-12-01

    In order to endow the commercial pure titanium dental implant material with antibacterial property and aimed at avoiding the invalidation that is caused by bacterial adhesion on the surface, a silver coating was fabricated via double glow plasma surface alloying. The antibacterial property of the silver coating was assessed via in vitro estimation. The results showed that a continuous and compact coating was formed. The silver coating had absolute superiority in antibacterial property to raw commercial pure titanium. Double glow plasma surface alloying with silver on commercial pure titanium dental implant material could be considered as a potentially effective method for preventing bacterial adhesion.

  2. Uniqueness of the equilibrium of an electron plasma on magnetic surfaces

    SciTech Connect

    Durand de Gevigney, Benoit

    2011-01-15

    The equilibrium of an electron plasma on magnetic surfaces is governed by a Poisson-Boltzmann equation. The electrons follow a Boltzmann distribution on each surface and the charge density depends exponentially on the electric potential. It is a well-known property that the classical Poisson's equation, for which the charge density is an independent parameter, possesses a unique solution provided suitable boundary conditions are given. Here we show that the Poisson-Boltzmann equation describing electron plasmas on magnetic surfaces also has a unique solution.

  3. Plasma immersion ion implantation for surface treatment of complex branched structures

    NASA Astrophysics Data System (ADS)

    Kashin, Oleg A.; Lotkov, Alexander I.; Borisov, Dmitry P.; Slabodchikov, Vladimir A.; Kuznetsov, Vladimir M.; Kudryashov, Andrey N.; Krukovsky, Konstantin V.

    2016-11-01

    The paper presents experimental results demonstrating the capabilities of plasma immersion ion implantation of silicon (Si) for surface treatment of complex branched structures such are self-expanding intravascular nickel-titanium (NiTi) stents. Using NiTi stents of diameter 4 and 8 mm, it is shown that plasma immersion ion implantation can provide rather homogeneous doping of their outer and inner surfaces with Si atoms. Also presented are research data on the processes that determine the thickness, composition, and structure of surface layers subjected to this type of treatment.

  4. Surface hardening of steel by boriding in a cold rf plasma

    NASA Technical Reports Server (NTRS)

    Finberg, I.; Avni, R.; Grill, A.; Spalvins, T.; Buckley, D. H.

    1985-01-01

    Scanning electron spectroscopy, X-ray diffractometry, Auger electron spectroscopy, and microhardness measurements, are used to study the surfaces of 4340-steel samples that have been borided in a cold RF plasma which had been initiated in a gas mixture of 2.7 percent diborane in Ar. As a result of the dislocation of the diborane in the plasma, boron is deposited on the surface of the steel substrate and two crystalline phases, tetragonal Fe2B and orthorhombic FeB, are formed. The formation of boride phases then increases the surface microhardness from 2650 MPa to a maximum value of 7740 MPa.

  5. Formation of surface nano-structures by plasma expansion induced by highly charged ions

    SciTech Connect

    Moslem, W. M.; El-Said, A. S.

    2012-12-15

    Slow highly charged ions (HCIs) create surface nano-structures (nano-hillocks) on the quartz surface. The formation of hillocks was only possible by surpassing a potential energy threshold. By using the plasma expansion approach with suitable hydrodynamic equations, the creation mechanism of the nano-hillocks induced by HCIs is explained. Numerical analysis reveal that within the nanoscale created plasma region, the increase of the temperature causes an increase of the self-similar solution validity domain, and consequently the surface nano-hillocks become taller. Furthermore, the presence of the negative (positive) nano-dust particles would lead to increase (decrease) the nano-hillocks height.

  6. Bohm potential effect on the propagation of electrostatic surface wave in semi-bounded quantum plasmas

    NASA Astrophysics Data System (ADS)

    Lee, Myoung-Jae; Jung, Young-Dae

    2017-02-01

    High frequency electrostatic wave propagation in a dense and semi-bounded electron quantum plasma is investigated with consideration of the Bohm potential. The dispersion relation for the surface mode of quantum plasma is derived and numerically analyzed. We found that the quantum effect enhances the frequency of the wave especially in the high wave number regime. However, the frequency of surface wave is found to be always lower than that of the bulk wave for the same quantum wave number. The group velocity of the surface wave for various quantum wave number is also obtained.

  7. Enhanced thermal stability of carbon nanotubes by plasma surface modification in Al2O3 composites

    NASA Astrophysics Data System (ADS)

    Cho, Hoonsung; Shi, Donglu; Guo, Yan; Lian, Jie; Ren, Zhifeng; Poudel, Bed; Song, Yi; Abot, Jandro L.; Singh, Dileep; Routbort, Jules; Wang, Lumin; Ewing, Rodney C.

    2008-10-01

    A plasma polymerization method was employed to deposit an ultrathin pyrrole film of 3 nm onto the surfaces of single wall carbon nanotubes (SWCNTs) and Al2O3 nanoparticles for developing high-strength nanocomposites. The surfaces of plasma coated SWCNTs and Al2O3 nanoparticles were studied by high resolution transmission electron microscopy (TEM) and time-of-flight secondary ion mass spectroscopy. After sintering the SWCNTs-Al2O3 composites at different temperatures (maximum of 1200 °C), the thermal stability of plasma-coated SWCNTs was significantly increased, compared to their uncoated counterparts. After hot-press sintering, the SWCNTs without plasma coating were essentially decomposed into amorphous clusters in the composites, leading to degraded mechanical properties. However, under the same sintering conditions, the plasma surface modified SWCNTs were well preserved and distributed in the composite matrices. The effects of plasma surface coating on the thermal stability of SWCNTs and mechanical behavior of the nanocomposites are discussed.

  8. Experimental demonstration of Martian soil simulant removal from a surface using a pulsed plasma jet

    NASA Astrophysics Data System (ADS)

    Ticoş, C. M.; Scurtu, A.; Toader, D.; Banu, N.

    2015-03-01

    A plasma jet produced in a small coaxial plasma gun operated at voltages up to 2 kV and working in pure carbon dioxide (CO2) at a few Torr is used to remove Martian soil simulant from a surface. A capacitor with 0.5 mF is charged up from a high voltage source and supplies the power to the coaxial electrodes. The muzzle of the coaxial plasma gun is placed at a few millimeters near the dusty surface and the jet is fired parallel with the surface. Removal of dust is imaged in real time with a high speed camera. Mars regolith simulant JSC-Mars-1A with particle sizes up to 5 mm is used on different types of surfaces made of aluminium, cotton fabric, polyethylene, cardboard, and phenolic.

  9. Challenges and opportunities of modeling plasma-surface interactions in tungsten using high-performance computing

    NASA Astrophysics Data System (ADS)

    Wirth, Brian D.; Hammond, K. D.; Krasheninnikov, S. I.; Maroudas, D.

    2015-08-01

    The performance of plasma facing components (PFCs) is critical for ITER and future magnetic fusion reactors. The ITER divertor will be tungsten, which is the primary candidate material for future reactors. Recent experiments involving tungsten exposure to low-energy helium plasmas reveal significant surface modification, including the growth of nanometer-scale tendrils of "fuzz" and formation of nanometer-sized bubbles in the near-surface region. The large span of spatial and temporal scales governing plasma surface interactions are among the challenges to modeling divertor performance. Fortunately, recent innovations in computational modeling, increasingly powerful high-performance computers, and improved experimental characterization tools provide a path toward self-consistent, experimentally validated models of PFC and divertor performance. Recent advances in understanding tungsten-helium interactions are reviewed, including such processes as helium clustering, which serve as nuclei for gas bubbles; and trap mutation, dislocation loop punching and bubble bursting; which together initiate surface morphological modification.

  10. Experimental demonstration of Martian soil simulant removal from a surface using a pulsed plasma jet.

    PubMed

    Ticoş, C M; Scurtu, A; Toader, D; Banu, N

    2015-03-01

    A plasma jet produced in a small coaxial plasma gun operated at voltages up to 2 kV and working in pure carbon dioxide (CO2) at a few Torr is used to remove Martian soil simulant from a surface. A capacitor with 0.5 mF is charged up from a high voltage source and supplies the power to the coaxial electrodes. The muzzle of the coaxial plasma gun is placed at a few millimeters near the dusty surface and the jet is fired parallel with the surface. Removal of dust is imaged in real time with a high speed camera. Mars regolith simulant JSC-Mars-1A with particle sizes up to 5 mm is used on different types of surfaces made of aluminium, cotton fabric, polyethylene, cardboard, and phenolic.

  11. Perspective of laser-induced plasma ignition of hydrocarbon fuel in Scramjet engine

    NASA Astrophysics Data System (ADS)

    Yang, Leichao; Li, Xiaohui; Liang, Jianhan; Yu, Xin; Li, Xipeng

    2016-01-01

    Laser-induced plasma ignition of an ethylene fuelled cavity was successfully conducted in a model scramjet engine combustor. The ethylene was injected 10mm upstream of cavity flameholder from 3 orifices 60 degree inclined relative to freestream direction. The 1064nm laser beam, from a Q-switched Nd:YAG laser source running at 3Hz and 200mJ per pulse, was focused into cavity for ignition. High speed photography was used to capture the transient ignition process. The laser-induced gas breakdown, flame kernel generation and propagation were all recorded and ensuing stable supersonic combustion was established in cavity. The flame kernel is found rotating anti-clockwise and gradually moves upwards as the entrainment of circulation flow in cavity. The flame is then stretched from leading edge to trailing edge to fully fill the entire cavity. Eventually, a stable combustion is achieved roughly 900μs after the laser pulse. The results show promising potentials for practical application. The perspective of laser-induced plasma ignition of hydrocarbon fuel in scramjet engine is outlined.

  12. Surface functionalization of an osteoconductive filler by plasma polymerization of poly(ε-caprolactone) and poly(acrylic acid) films

    NASA Astrophysics Data System (ADS)

    Petisco-Ferrero, S.; Sánchez-Ilárduya, M. B.; Díez, A.; Martín, L.; Meaurio Arrate, E.; Sarasua, J. R.

    2016-11-01

    One of the major limitations found in the use of nanocomposites based on synthetic hydroxyapatite and polymeric matrix for bone-tissue regeneration lies in the poor interfacial adhesion between the inorganic filler and the polymer matrix. The integrity of the nanocomposite is severely compromised since, on the one hand, high surface fillers tend to form aggregates and on the other, there is no chemical bonding between these two different categories of materials. Thus, customized surface functionalization stands as an effective route to improve the interfacial behaviour between particles and polymeric matrices. Amongst the current state of development of coating technologies, the high film-chemistry controllability offered by plasma polymerization technology enhances the synthesis of polymeric films from virtually any starting organic monomer. In this sense, the work presented here provides strong evidences of surface functionalization achieved by plasma polymerization starting respectively from ε-caprolactone and acrylic acid monomers. The chemistry of the deposited films has been descriptively analysed by XPS demonstrating outstanding retention of monomer functionalities and FTIR spectra of the deposited films revealed a high resemblance to those obtained by conventional synthesis. Results provided thereof are expected to significantly contribute to improve the interfacial behaviour in terms of matrix-reinforcement compatibilization, of crucial importance for bone-tissue engineering applications.

  13. Plasmas fluxes to surfaces for an oblique magnetic field

    SciTech Connect

    Pitcher, C.S.; Stangeby, P.C.; Elder, J.D.; Bell, M.G.; Kilpatrick, S.J.; Manos, D.M.; Medley, S.S.; Owens, D.K.; Ramsey, A.T.; Ulrickson, M.

    1992-07-01

    The poloidal and toroidal spatial distributions of D{sub {alpha}}, He I and C II emission have been obtained in the vicinity of the TFTR bumper limiter and are compared with models of ion flow to the surface. The distributions are found not to agree with a model (the ``Cosine`` model) which determines the incident flux density using only the parallel fluxes in the scrape-off layer and the projected area of the surface perpendicular to the field lines. In particular, the Cosine model is not able to explain the significant fluxes observed at locations on the surface which are oblique to the magnetic field. It is further shown that these fluxes cannot be explained by the finite Larmor radius of impinging ions. Finally, it is demonstrated, with the use of Monte Carlo codes, that the distributions can be explained by including both parallel and cross-field transport onto the limiter surface.

  14. Plasmas fluxes to surfaces for an oblique magnetic field

    SciTech Connect

    Pitcher, C.S. ); Stangeby, P.C.; Elder, J.D. ); Bell, M.G.; Kilpatrick, S.J.; Manos, D.M.; Medley, S.S.; Owens, D.K.; Ramsey, A.T.; Ulrickson, M. . Plasma Physics Lab.)

    1992-07-01

    The poloidal and toroidal spatial distributions of D{sub {alpha}}, He I and C II emission have been obtained in the vicinity of the TFTR bumper limiter and are compared with models of ion flow to the surface. The distributions are found not to agree with a model (the Cosine'' model) which determines the incident flux density using only the parallel fluxes in the scrape-off layer and the projected area of the surface perpendicular to the field lines. In particular, the Cosine model is not able to explain the significant fluxes observed at locations on the surface which are oblique to the magnetic field. It is further shown that these fluxes cannot be explained by the finite Larmor radius of impinging ions. Finally, it is demonstrated, with the use of Monte Carlo codes, that the distributions can be explained by including both parallel and cross-field transport onto the limiter surface.

  15. Efficient cesiation in RF driven surface plasma negative ion source

    SciTech Connect

    Belchenko, Yu.; Ivanov, A.; Konstantinov, S.; Sanin, A. Sotnikov, O.

    2016-02-15

    Experiments on hydrogen negative ions production in the large radio-frequency negative ion source with cesium seed are described. The system of directed cesium deposition to the plasma grid periphery was used. The small cesium seed (∼0.5 G) provides an enhanced H{sup −} production during a 2 month long experimental cycle. The gradual increase of negative ion yield during the long-term source runs was observed after cesium addition to the source. The degraded H{sup −} production was recorded after air filling to the source or after the cesium washing away from the driver and plasma chamber walls. The following source conditioning by beam shots produces the gradual recovery of H{sup −} yield to the high value. The effect of H{sup −} yield recovery after cesium coverage passivation by air fill was studied. The concept of cesium coverage replenishment and of H{sup −} yield recovery due to sputtering of cesium from the deteriorated layers is discussed.

  16. Ion Velocity Phase Space Studies of the VASIMR Engine Exhaust Plasma

    NASA Astrophysics Data System (ADS)

    Bering, III; Chang-Diaz, F. R.; Squire, J.; Jacobson, V.; Tarditi, A.; Bengtson, R. D.; Glover, T. W.; Brukardt, M.; McCaskill, G. E.

    2004-11-01

    The Variable Specific Impulse Magnetoplasma Rocket (VASIMR) is a high power engine capable of Isp/thrust modulation at constant power. The plasma is produced by helicon discharge. The bulk of the energy is added by ion cyclotron resonance heating (ICRH.) Axial momentum is obtained by adiabatic expansion of the plasma in a magnetic nozzle. Thrust/specific impulse ratio control in the VASIMR is primarily achieved by the partitioning of the RF power to the helicon and ICRH systems, with the proper adjustment of the propellant flow. Ion dynamics in the exhaust were studied using probes, gridded energy analyzers (RPAÂ's), microwave interferometry and optical techniques. This paper will focus on the RPA data. We will examine the ion dynamics in a deuterium exhaust plasma using ˜9 kW of RF power to the helicon ionization stage and varying power levels to the ICRH acceleration stage. Ion heating of ˜70 eV/ion/kW of applied ICRH has been demonstrated. Results also confirm conversion of transverse ion motion to axial motion.

  17. Comprehensive characterization of chondrocyte cultures in plasma and whole blood biomatrices for cartilage tissue engineering.

    PubMed

    Schulz, Ronny M; Haberhauer, Marcus; Zernia, Göran; Pösel, Claudia; Thümmler, Christian; Somerson, Jeremy S; Huster, Daniel

    2014-07-01

    Many synthetic polymers and biomaterials have been used as matrices for 3D chondrocyte seeding and transplantation in the field of cartilage tissue engineering. To develop a fully autologous carrier for chondrocyte cultivation, we examined the feasibility of allogeneic plasma and whole blood-based matrices and compared them to agarose constructs. Primary articular chondrocytes isolated from 12-month-old pigs were embedded into agarose, plasma and whole blood matrices and cultivated under static-free swelling conditions for up to four weeks. To evaluate the quality of the synthesized extracellular matrix (ECM), constructs were subjected to weekly examinations using histological staining, spectrophotometry, immunohistochemistry and biochemical analysis. In addition, gene expression of cartilage-specific markers such as aggrecan, Sox9 and collagen types I, II and X was determined by RT-PCR. Chondrocyte morphology was assessed via scanning electron microscopy and viability staining, including proliferation and apoptosis assays. Finally, (13)  C NMR spectroscopy provided further evidence of synthesis of ECM components. It was shown that chondrocyte cultivation in allogeneic plasma and whole-blood matrices promoted sufficient chondrocyte viability and differentiation behaviour, resulting in neo-formation of a hyaline-like cartilage matrix.

  18. Designed synthesis and surface engineering strategies of magnetic iron oxide nanoparticles for biomedical applications.

    PubMed

    Wu, Wei; Jiang, Chang Zhong; Roy, Vellaisamy A L

    2016-12-01

    Iron oxide nanoparticles (NPs) hold great promise for future biomedical applications because of their magnetic properties as well as other intrinsic properties such as low toxicity, colloidal stability, and surface engineering capability. Numerous related studies on iron oxide NPs have been conducted. Recent progress in nanochemistry has enabled fine control over the size, crystallinity, uniformity, and surface properties of iron oxide NPs. This review examines various synthetic approaches and surface engineering strategies for preparing naked and functional iron oxide NPs with different physicochemical properties. Growing interest in designed and surface-engineered iron oxide NPs with multifunctionalities was explored in in vitro/in vivo biomedical applications, focusing on their combined roles in bioseparation, as a biosensor, targeted-drug delivery, MR contrast agents, and magnetic fluid hyperthermia. This review outlines the limitations of extant surface engineering strategies and several developing strategies that may overcome these limitations. This study also details the promising future directions of this active research field.

  19. The Effects of Using a Commercial Grade Plasma Etching Chamber to Etch Anodized Niobium Surfaces

    NASA Astrophysics Data System (ADS)

    Epperson, Christiana; Drake, Dereth; Winska, Kalina

    2015-11-01

    Anodized niobium surfaces are used in particle accelerators for construction of the superconducting cavities. These surfaces must be cleaned regularly to remove containments and maintain the surface smoothness. The most common method used is that of chemically etching the surface using acid baths; however, this process can affect the smoothness of the layer and is extremely time consuming and hazardous. Plasma etching is one alternative that has shown great promise. We are using a commercial grade plasma etching chamber to clean anodized niobium samples that have varying oxide layer thicknesses. Spectral profiles of the surfaces of the samples are taken before and after etching. All measured results are compared to a simple theoretical model in order to determine the effects of the etching process on each surface.

  20. Towards Enhanced Performance Thin-film Composite Membranes via Surface Plasma Modification

    NASA Astrophysics Data System (ADS)

    Reis, Rackel; Dumée, Ludovic F.; Tardy, Blaise L.; Dagastine, Raymond; Orbell, John D.; Schutz, Jürg A.; Duke, Mikel C.

    2016-07-01

    Advancing the design of thin-film composite membrane surfaces is one of the most promising pathways to deal with treating varying water qualities and increase their long-term stability and permeability. Although plasma technologies have been explored for surface modification of bulk micro and ultrafiltration membrane materials, the modification of thin film composite membranes is yet to be systematically investigated. Here, the performance of commercial thin-film composite desalination membranes has been significantly enhanced by rapid and facile, low pressure, argon plasma activation. Pressure driven water desalination tests showed that at low power density, flux was improved by 22% without compromising salt rejection. Various plasma durations and excitation powers have been systematically evaluated to assess the impact of plasma glow reactions on the physico-chemical properties of these materials associated with permeability. With increasing power density, plasma treatment enhanced the hydrophilicity of the surfaces, where water contact angles decreasing by 70% were strongly correlated with increased negative charge and smooth uniform surface morphology. These results highlight a versatile chemical modification technique for post-treatment of commercial membrane products that provides uniform morphology and chemically altered surface properties.

  1. Towards Enhanced Performance Thin-film Composite Membranes via Surface Plasma Modification.

    PubMed

    Reis, Rackel; Dumée, Ludovic F; Tardy, Blaise L; Dagastine, Raymond; Orbell, John D; Schutz, Jürg A; Duke, Mikel C

    2016-07-01

    Advancing the design of thin-film composite membrane surfaces is one of the most promising pathways to deal with treating varying water qualities and increase their long-term stability and permeability. Although plasma technologies have been explored for surface modification of bulk micro and ultrafiltration membrane materials, the modification of thin film composite membranes is yet to be systematically investigated. Here, the performance of commercial thin-film composite desalination membranes has been significantly enhanced by rapid and facile, low pressure, argon plasma activation. Pressure driven water desalination tests showed that at low power density, flux was improved by 22% without compromising salt rejection. Various plasma durations and excitation powers have been systematically evaluated to assess the impact of plasma glow reactions on the physico-chemical properties of these materials associated with permeability. With increasing power density, plasma treatment enhanced the hydrophilicity of the surfaces, where water contact angles decreasing by 70% were strongly correlated with increased negative charge and smooth uniform surface morphology. These results highlight a versatile chemical modification technique for post-treatment of commercial membrane products that provides uniform morphology and chemically altered surface properties.

  2. Towards Enhanced Performance Thin-film Composite Membranes via Surface Plasma Modification

    PubMed Central

    Reis, Rackel; Dumée, Ludovic F.; Tardy, Blaise L.; Dagastine, Raymond; Orbell, John D.; Schutz, Jürg A.; Duke, Mikel C.

    2016-01-01

    Advancing the design of thin-film composite membrane surfaces is one of the most promising pathways to deal with treating varying water qualities and increase their long-term stability and permeability. Although plasma technologies have been explored for surface modification of bulk micro and ultrafiltration membrane materials, the modification of thin film composite membranes is yet to be systematically investigated. Here, the performance of commercial thin-film composite desalination membranes has been significantly enhanced by rapid and facile, low pressure, argon plasma activation. Pressure driven water desalination tests showed that at low power density, flux was improved by 22% without compromising salt rejection. Various plasma durations and excitation powers have been systematically evaluated to assess the impact of plasma glow reactions on the physico-chemical properties of these materials associated with permeability. With increasing power density, plasma treatment enhanced the hydrophilicity of the surfaces, where water contact angles decreasing by 70% were strongly correlated with increased negative charge and smooth uniform surface morphology. These results highlight a versatile chemical modification technique for post-treatment of commercial membrane products that provides uniform morphology and chemically altered surface properties. PMID:27363670

  3. Measurements of the momentum flux from a low-temperature plasma to a surface

    NASA Astrophysics Data System (ADS)

    Trottenberg, Thomas

    2016-09-01

    The forces that low-temperature plasmas exert on surfaces in contact with the plasma have never been a significant topic. The reason might be the smallness of such forces and the expected difficulties in their measurement. Therefore, only in cases of special plasmas which were designed for the generation of directed momentum (in particular electric space propulsion), force measurements have been reported. Recently, our group demonstrated that the forces related to plasma-wall interactions are experimentally accessible with some effort. This presentation overviews our experimental approaches in the design of force measuring probes and reports on recent measurements with probes that have been integrated into a plane wall. The observations and prospects for an application as novel plasma diagnostic are discussed. This work was financially supported by the German Aerospace Center (DLR) under grant agreement 50 RS 1301.

  4. Boundary Layer Flow Control with a One Atmosphere Uniform Glow Discharge Surface Plasma

    NASA Technical Reports Server (NTRS)

    Roth, J. Reece; Sherman, Daniel M.; Wilkinson, Stephen P.

    1998-01-01

    Low speed wind tunnel data have been acquired for planar panels covered by a uniform, glow-discharge surface plasma in atmospheric pressure air known as the One Atmosphere Uniform Glow Discharge Plasma (OAUGDP). Streamwise and spanwise arrays of flush, plasma-generating surface electrodes have been studied in laminar, transitional, and fully turbulent boundary layer flow. Plasma between symmetric streamwise electrode strips caused large increases in panel drag, whereas asymmetric spanwise electrode configurations produced a significant thrust. Smoke wire flow visualization and mean velocity diagnostics show the primary cause of the phenomena to be a combination of mass transport and vortical structures induced by strong paraelectric ElectroHydroDynamic (EHD) body forces on the flow.

  5. Excitation of surface modes by electron beam in semi-bounded quantum plasma

    SciTech Connect

    Mohamed, B. F.; Elbasha, N. M.

    2015-10-15

    The excitation of the TM surface modes due to the interaction of electron beam with a semi-bounded quantum magnetized plasma is investigated. The generated current and the perturbed densities of the electron beam and plasma are obtained. The wave equation that describes the excited fields has been solved to obtain the dispersion relation for these modes. It is found that the quantum effects play important role for frequencies less and bigger than plasma frequency such that the phase velocity of modes increases with increasing the quantum effects compared to the classical case. It has also been displayed that in the absence of external magnetic field, the surface modes appear in the all regions of the wavelength while they have been only excited for high wavenumber in the presence of the magnetic field. Besides, it has been shown that the dispersion curves of the modes depend essentially on the density ratio of beam and plasma.

  6. Theory of ground surface plasma wave associated with pre-earthquake electrical charges

    NASA Astrophysics Data System (ADS)

    Fujii, Masafumi

    2013-03-01

    is shown theoretically that if mobile electrical charge exists on the surface of the ground, a ground surface plasma wave is induced by radio waves. If the electrical charges are generated by tectonic stresses acting on crustal rocks prior to major earthquakes, the detection of a ground surface plasma wave could be used as a pre-earthquake electromagnetic phenomenon. The ground surface plasma wave has a dispersion relation, i.e., the relation between frequency and wavelength, similar to that of the free-space plane wave in the atmosphere over the radio broadcast frequency range. It allows for a strong coupling between these two types of waves. This is a mode of electromagnetic wave propagation that has not been previously reported. Numerical analysis demonstrates (1) the propagation of the ground surface plasma wave along a curved surface beyond the line of sight, (2) anomalous scattering by ground surface roughness, and (3) the generation of cross-polarized waves due to the scattering. These results all agree well with radio wave anomalies observed before large earthquakes.

  7. Engineering of Surface Chemistry for Enhanced Sensitivity in Nanoporous Interferometric Sensing Platforms.

    PubMed

    Law, Cheryl Suwen; Sylvia, Georgina M; Nemati, Madieh; Yu, Jingxian; Losic, Dusan; Abell, Andrew D; Santos, Abel

    2017-03-15

    We explore new approaches to engineering the surface chemistry of interferometric sensing platforms based on nanoporous anodic alumina (NAA) and reflectometric interference spectroscopy (RIfS). Two surface engineering strategies are presented, namely (i) selective chemical functionalization of the inner surface of NAA pores with amine-terminated thiol molecules and (ii) selective chemical functionalization of the top surface of NAA with dithiol molecules. The strong molecular interaction of Au(3+) ions with thiol-containing functional molecules of alkane chain or peptide character provides a model sensing system with which to assess the sensitivity of these NAA platforms by both molecular feature and surface engineering. Changes in the effective optical thickness of the functionalized NAA photonic films (i.e., sensing principle), in response to gold ions, are monitored in real-time by RIfS. 6-Amino-1-hexanethiol (inner surface) and 1,6-hexanedithiol (top surface), the most sensitive functional molecules from approaches i and ii, respectively, were combined into a third sensing strategy whereby the NAA platforms are functionalized on both the top and inner surfaces concurrently. Engineering of the surface according to this approach resulted in an additive enhancement in sensitivity of up to 5-fold compared to previously reported systems. This study advances the rational engineering of surface chemistry for interferometric sensing on nanoporous platforms with potential applications for real-time monitoring of multiple analytes in dynamic environments.

  8. Oxygen plasma damage to blanket and patterned ultralow-{kappa} surfaces

    SciTech Connect

    Bao, J.; Shi, H.; Huang, H.; Ho, P. S.; McSwiney, M. L.; Goodner, M. D.; Moinpour, M.; Kloster, G. M.

    2010-03-15

    Oxygen plasma damage to blanket and patterned ultralow-{kappa} (ULK) dielectric surfaces was investigated by examining the effect of plasma species and dielectric materials. Blanket ULK films and patterned structures were treated by O{sub 2} plasma in a remote plasma chamber where the ions and radicals from the plasma source can be separately controlled to study their respective roles in the damage process. The plasma damage was characterized by angle resolved x-ray photoelectron spectroscopy, x-ray reflectivity, and Fourier transform infrared spectroscopy. Studies of the angle dependence of oxygen plasma damage to blanket ULK films indicated that damage by ions was anisotropic while that by radicals was isotropic. Ions were found to play an important role in assisting carbon depletion by oxygen radicals on the blanket film surface. More plasma damage was observed with increasing porosity in ultralow-{kappa} films. Probable reaction paths were proposed by analyzing the reaction by-products. Plasma damage to the sidewall of low-{kappa} trenches was examined by electron energy loss (EELS) analysis. The depletion depth of carbon was found to be related to the penetration of radical species into the porous dielectric and the distribution at the sidewall and trench bottom was affected by the trench pattern geometry, i.e., the aspect ratio, which can be correlated with the electron potential distribution and subsequent trajectory of ions. Vapor silylation was applied for dielectric recovery of trench structure and the result was examined by EELS. The trimethylchlorosilane was found to be effective for recovery of the sidewall carbon loss. The recovery was better for loss induced by radical O{sub 2} than by hybrid O{sub 2} and the difference was attributed to the surface densification by ions limiting the mass transport of vapor chemicals.

  9. Plasma development in the early phase of vacuum surface flashover

    SciTech Connect

    Masten, G.; Mueller, T.; Hegeler, F.; Krompholz, H. . Dept. of Electrical Engineering and Physics)

    1994-12-01

    The primary physical mechanism responsible for charge-carrier amplification, in a developing surface discharge, has eluded conclusive identification for decades. This paper describes the results of experiments to directly detect charge-carriers, above the dielectric surface, within the developing discharge. Free electrons are detected by measuring the deflection of a laser beam, focused to a 20 [mu]m 1/e diameter, with an angular sensitivity of 0.18 mV/[mu]rad and a risetime of 6 ns. The estimated detection threshold for electrons in the developing discharge is 10[sup 16] cm[sup [minus]3] to 10[sup 17] cm[sup [minus]3]. A streak camera is used to gather spatial information regarding luminous processes with a maximum resolution of 25 [mu]m and 0.6 ns. Current measurements have a sub-nanosecond response time and a detection threshold of 100 mA. Laser deflection measurements demonstrate the rapid development of a particle gradient, generally within 10 [mu]m of the surface near the cathode and in the range of 75 to 175 [mu]m from the surface near the anode, during the developing discharge. Streak camera measurements demonstrate the formation of an intense, visible emission, 25 to 50 [mu]m in diameter, located near the insulator surface, during the formation of the discharge. These results imply that charge-carrier amplification occurs above the surface of the insulator, in a region of neutral particles desorbed or otherwise ejected from the insulator surface.

  10. Effects of plasma on polyethylene fiber surface for prosthodontic application

    PubMed Central

    SPYRIDES, Silvana Marques Miranda; do PRADO, Maíra; de ARAUJO, Joyce Rodrigues; SIMÃO, Renata Antoun; BASTIAN, Fernando Luis

    2015-01-01

    ABSTRACT Plasma technology has the potential to improve the adherence of fibers to polymeric matrices, and there are prospects for its application in dentistry to reinforce the dental particulate composite. Objectives This study aimed to investigate the effect of oxygen or argon plasma treatment on polyethylene fibers. Material and Methods Connect, Construct, InFibra, and InFibra treated with oxygen or argon plasma were topographically evaluated by scanning electron microscopy (SEM), and chemically by X-ray photoelectron spectroscopy (XPS). For bending analysis, one indirect composite (Signum) was reinforced with polyethylene fiber (Connect, Construct, or InFibra). The InFibra fiber was subjected to three different treatments: (1) single application of silane, (2) oxygen or argon plasma for 1 or 3 min, (3) oxygen or argon plasma and subsequent application of silane. The samples (25x2x2 mm), 6 unreinforced and 60 reinforced with fibers, were subjected to three-point loading tests to obtain their flexural strength and deflection. The results were statistically analyzed with ANOVA and the Bonferroni correction for multiple comparison tests. Results SEM analysis showed that oxygen and argon plasma treatments promote roughness on the polyethylene fiber surface. X-ray photoelectron spectroscopy (XPS) analysis shows that both plasmas were effective in incorporating oxygenated functional groups. Argon or oxygen plasma treatment affected the flexural strength and deflection of a fiber reinforced composite. The application of silane does not promote an increase in the flexural strength of the reinforced composites. Conclusions Oxygen and argon plasma treatments were effective in incorporating oxygenated functional groups and surface roughness. The highest strength values were obtained in the group reinforced with polyethylene fibers treated with oxygen plasma for 3 min. PMID:26814463

  11. Plasma channel created by ionization of gas by a surface wave

    SciTech Connect

    Konovalov, V. N.; Kuz’min, G. P.; Minaev, I. M. Rukhadze, A. A.; Tikhonevich, O. V.

    2015-09-15

    Conditions for gas ionization in the field of a slow surface wave excited by a microwave source are considered. The gas ionization rate and the plasma density distribution over the radius of the discharge tube were studied by the optical method. The experiments were conducted in a dielectric tube with a radius much smaller than the tube length, the gas pressure being ∼1–3 Torr. It is shown that the stationary distribution of the plasma density is determined by diffusion processes.

  12. 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.

  13. Study of carboxylic functionalization of polypropylene surface using the underwater plasma technique

    NASA Astrophysics Data System (ADS)

    Joshi, R. S.; Friedrich, J. F.; Wagner, M. H.

    2009-08-01

    Non-equilibrium solution plasma treatment of polymer surfaces in water offers the possibility of more dense and selective polymer surface functionalization in comparison to the well-known and frequently used low-pressure oxygen plasma. Functional groups are introduced when the polymer surface contacts the plasma moderated solution especially water solutions. The emission of ions, electrons, energy-rich neutrals and complexes, produced by the ion avalanche are limited by quenching, with the aid of the ambient water phase. The UV-radiation produced in plasma formation also helps to moderate the reaction solution further by producing additional excited, ionized/dissociated molecules. Thus, monotype functional groups equipped polymer surfaces, preferably OH groups, originating from the dissociated water molecules, could be produced more selectively. An interesting feature of the technique is its flexibility to use a wide variety of additives in the water phase. Another way to modify polymer surfaces is the deposition of plasma polymers carrying functional groups as carboxylic groups used in this work. Acetic acid, acrylic acid, maleic and itaconic acid were used as additive monomers. Acetic acid is not a chemically polymerizing monomer but it could polymerize by monomer/molecular fragmentation and recombination to a cross linked layer. The other monomers form preferably water-soluble polymers on a chemical way. Only the fragmented fraction of these monomers could form an insoluble coating by cross linking to substrate. The XPS analysis was used to track the alterations in -O-CO- bond percentage on the PP surface. To identify the -COOH groups on substrate surface unambiguously, which have survived the plasma polymerization process, the derivatization with trifluoroethanol was performed.

  14. Essential Characteristics of Plasma Antennas Driven by One-ended Surface Wave

    NASA Astrophysics Data System (ADS)

    Wang, Shiqing; Sun, Naifeng; Li, Jian; Xiang, Qian; Wei, Chaolei

    2010-04-01

    Based on the principle that one-ended electromagnetic surface wave can drive a plasma antenna, the relation between the effective length of an antenna column and the applied radio frequency (RF) power was studied both theoretically and experimentally. The density distribution along the antenna column as well as the electron temperature in different conditions were investigated. The characteristics of the reception of local frequency modulated (FM) electromagnetic wave by the plasma antenna were compared with that by a copper antenna with same dimensions. The results show that it is feasible to take plasma antennas as receiving ones.

  15. Effects of plasma treatment on surface properties of ultrathin layered MoS2

    NASA Astrophysics Data System (ADS)

    Kim, Suhhyun; Choi, Min Sup; Qu, Deshun; Ra, Chang Ho; Liu, Xiaochi; Kim, Minwoo; Song, Young Jae; Jong Yoo, Won

    2016-09-01

    This work investigates the use of oxygen plasma (O2) treatment, applied as an inductively coupled plasma, to control the thickness and work function of a MoS2 layer. Plasma-etched MoS2 exhibited a surface roughness similar to that of the pristine MoS2. The MoS2 field effect transistors fabricated using the plasma-etched MoS2 displayed a higher n-type doping concentration than that of pristine MoS2. The x-ray photoelectron spectroscopy was performed to analyze chemical composition to demonstrate the minimum level of chemical reactions occurred upon plasma treatment. Moreover, Kelvin probe force microscopy measurements were conducted to probe the changes in the work function that could be attributed to the changes in the surface potential. The measured work functions suggest the modification of a band structure and n-doping effect after plasma treatments that depended on the number of MoS2 layers. This study suggests that the O2 plasma can control the layer number of the MoS2 as well as the electronic properties of a MoS2 film.

  16. Formation and characterization of hydrophobic glass surface treated by atmospheric pressure He/CH4 plasma

    NASA Astrophysics Data System (ADS)

    Noh, Sooryun; Youn Moon, Se

    2014-01-01

    Atmospheric pressure helium plasmas, generated in the open air by 13.56 MHz rf power, were applied for the glass surface wettability modification. The plasma gas temperature, measured by the spectroscopic method, was under 400 K which is low enough to treat the samples without thermal damages. The hydrophobicity of the samples determined by the water droplet contact angle method was dependent on the methane gas content and the plasma exposure time. Adding the methane gas by a small amount of 0.25%, the contact angle was remarkably increased from 10° to 83° after the 10 s plasma treatment. From the analysis of the treated surface and the plasma, it was shown that the deposition of alkane functional groups such as C-H stretch, CH2 bend, and CH3 bend was one of the contributing factors for the hydrophobicity development. In addition, the hydrophobic properties lasted over 2 months even after the single treatment. From the results, the atmospheric pressure plasma treatment promises the fast and low-cost method for the thermally-weak surface modification.

  17. Curling probe measurement of large-volume pulsed plasma confined by surface magnetic field

    NASA Astrophysics Data System (ADS)

    Pandey, Anil; Sakakibara, Wataru; Matsuoka, Hiroyuki; Nakamura, Keiji; Sugai, Hideo; Chubu University Team; DOWA Thermotech Collaboration

    2015-09-01

    Curling probe (CP) has recently been developed which enables the local electron density measurement even in plasma for non-conducting film CVD. The electron density is obtained from a shift of resonance frequency of spiral antenna in discharge ON and OFF monitored by a network analyzer (NWA). In case of a pulsed glow discharge, synchronization of discharge pulse with frequency sweep of NWA must be established. In this paper, we report time and space-resolved CP measurement of electron density in a large volume plasma (80 cm diameter, 110 cm length) confined by surface magnetic field (multipole cusp field ~0.03 T). For plasma-aided modification of metal surface, the plasma is produced by 1 kV glow discharge at pulse frequency of 0.3 - 25 kHz with various duty ratio in gas (Ar, N2, C2H2) at pressure ~ 1 Pa. A radially movable CP revealed a remarkable effect of surface magnetic confinement: detach of plasma from the vessel wall and a fairly uniform plasma in the central region. In afterglow phase, the electron density was observed to decrease much faster in C2H2 discharge than in Ar discharge.

  18. A thin transition film formed by plasma exposure contributes to the germanium surface hydrophilicity

    NASA Astrophysics Data System (ADS)

    Shumei, Lai; Danfeng, Mao; Zhiwei, Huang; Yihong, Xu; Songyan, Chen; Cheng, Li; Wei, Huang; Dingliang, Tang

    2016-09-01

    Plasma treatment and 10% NH4OH solution rinsing were performed on a germanium (Ge) surface. It was found that the Ge surface hydrophilicity after O2 and Ar plasma exposure was stronger than that of samples subjected to N2 plasma exposure. This is because the thin GeO x film formed on Ge by O2 or Ar plasma is more hydrophilic than GeO x N y formed by N2 plasma treatment. A flat (RMS < 0:5 nm) Ge surface with high hydrophilicity (contact angle smaller than 3°) was achieved by O2 plasma treatment, showing its promising application in Ge low-temperature direct wafer bonding. Project supported by the Key Project of Natural Science Foundation of China (No. 61534005), the National Science Foundation of China (No. 61474081), the National Basic Research Program of China (No. 2013CB632103), the Natural Science Foundation of Fujian Province (No. 2015D020), and the Science and Technology Project of Xiamen City (No. 3502Z20154091).

  19. Effect of Plasma Surface Finish on Wettability and Mechanical Properties of SAC305 Solder Joints

    NASA Astrophysics Data System (ADS)

    Kim, Kyoung-Ho; Koike, Junichi; Yoon, Jeong-Won; Yoo, Sehoon

    2016-12-01

    The wetting behavior, interfacial reactions, and mechanical reliability of Sn-Ag-Cu solder on a plasma-coated printed circuit board (PCB) substrate were evaluated under multiple heat-treatments. Conventional organic solderability preservative (OSP) finished PCBs were used as a reference. The plasma process created a dense and highly cross-linked polymer coating on the Cu substrates. The plasma finished samples had higher wetting forces and shorter zero-cross times than those with OSP surface finish. The OSP sample was degraded after sequential multiple heat treatments and reflow processes, whereas the solderability of the plasma finished sample was retained after multiple heat treatments. After the soldering process, similar microstructures were observed at the interfaces of the two solder joints, where the development of intermetallic compounds was observed. From ball shear tests, it was found that the shear force for the plasma substrate was consistently higher than that for the OSP substrate. Deterioration of the OSP surface finish was observed after multiple heat treatments. Overall, the plasma surface finish was superior to the conventional OSP finish with respect to wettability and joint reliability, indicating that it is a suitable material for the fabrication of complex electronic devices.

  20. Plasma-enhanced deposition of antifouling layers on silicone rubber surfaces

    NASA Astrophysics Data System (ADS)

    Jiang, Hongquan

    In food processing and medical environments, biofilms serve as potential sources of contamination, and lead to food spoilage, transmission of diseases or infections. Because of its ubiquitous and recalcitrant nature, Listeria monocytogenes biofilm is especially hard to control. Generating antimicrobial surfaces provide a method to control the bacterial attachment. The difficulty of silver deposition on polymeric surfaces has been overcome by using a unique two-step plasma-mediated method. First silicone rubber surfaces were plasma-functionalized to generate aldehyde groups. Then thin silver layers were deposited onto the functionalized surfaces according to Tollen's reaction. X-ray photoelectron spectroscopy (XPS), atomic force spectroscopy (AFM) and scanning electron microscopy (SEM) showed that silver particles were deposited. By exposing the silver coated surfaces to L. monocytogenes, it was demonstrated that they were bactericidal to L. monocytogenes. No viable bacteria were detected after 12 to 18 h on silver-coated silicone rubber surfaces. Another antifouling approach is to generate polyethylene glycol (PEG) thin layer instead of silver on polymer surfaces. Covalent bond of PEG structures of various molecular weights to cold-plasma-functionalized polymer surfaces, such as silicone rubber, opens up a novel way for the generation of PEG brush-like or PEG branch-like anti-fouling layers. In this study, plasma-generated surface free radicals can react efficiently with dichlorosilane right after plasma treatment. With the generation of halo-silane groups, this enables PEG molecules to be grafted onto the modified surfaces. XPS data clearly demonstrated the presence of PEG molecules on plasma-functionalized silicone rubber surfaces. AFM images showed the changed surface morphologies as a result of covalent attachment to the surface of PEG molecules. Biofilm experiment results suggest that the PEG brush-like films have the potential ability to be the next

  1. Enhancing surface functionality of reduced graphene oxide biosensors by oxygen plasma treatment for Alzheimer's disease diagnosis.

    PubMed

    Chae, Myung-Sic; Kim, Jinsik; Jeong, Dahye; Kim, YoungSoo; Roh, Jee Hoon; Lee, Sung Min; Heo, Youhee; Kang, Ji Yoon; Lee, Jeong Hoon; Yoon, Dae Sung; Kim, Tae Geun; Chang, Suk Tai; Hwang, Kyo Seon

    2017-06-15

    We performed oxygen plasma treatment on reduced graphene oxide (rGO) to improve its surface reactivity with respect to biomolecular interactions. Oxygen-plasma-treated rGO surfaces were employed as reactive interfaces for the detection of amyloid-beta (Aβ) peptides, the pathological hallmarks of Alzheimer's disease (AD), as the target analytes. By measuring the changes in electrical characteristics and confirmation through topographic analysis, the oxygen-plasma-treated rGO sensors had enhanced surface functionality for better antibody immobilization and sensing performance, with a 3.33-fold steeper slope for the electrical responses versus analyte concentration curve (logarithmic scale) compared to the untreated. The elicited biomolecular reactivity of the rGO surfaces with the oxygen plasma treatment remained at 46-51% of the initial value even after aging for 6h in ambient conditions. This phenomenon was also confirmed by pretreating the rGO surfaces with a blocking agent and subsequently subjecting them to antibody immobilization. Finally, the feasibility of the oxygen-plasma-treated rGO sensors as a diagnostic tool was evaluated with clinical samples of neural-derived exosomal Aβ peptides extracted from apparent AD patients and normal controls (NC). In contrast to the untreated sensors (p=0.0460), the oxygen-plasma-treated rGO sensors showed a significant p-value in the identification of clinical samples of AD and NC subjects (p<0.001). These results suggest that oxygen plasma treatment improves sensor performance without complicated fabrication procedures and should aid in the development of novel diagnostic tools based on carbon nanomaterials.

  2. Molecular Engineering of Surfaces for Sensing and Detection

    DTIC Science & Technology

    2005-08-01

    difference in protein orientation on different charged surfaces. Surface Plasmon Resonance ( SPR ) and Time-of-Flight Secondary Ion Mass Spectrometry (ToF...6 SPR STUDY OF PROTEIN ORIENTATION ON CHARGED SURFACES...THE LOW DETECTION REGION. ........................81 FIGURE 7.5 COMPENSATED SPR RESPONSE SHOWING A) A DETECTION OF 0.5 NG/ML AND B) NO CLEAR DETECTION

  3. Surface Activation of Plane and Curved Automotive Polymer Surfaces by Using a Fittable Multi-Pin DBD Plasma Source

    NASA Astrophysics Data System (ADS)

    Jörn, Heine; Roland, Damm; Christoph, Gerhard; Stephan, Wieneke; Wolfgang, Viöl

    2014-06-01

    In this work, surface activation of automotive polymers using atmospheric pressure plasmas was investigated. The aim was to increase the polar fraction of the surface energy of both plane and convex polymer devices with a radius in the range of 30 mm. For this purpose, a fittable low temperature atmospheric pressure plasma source based on capacitively coupled multi-pin electrodes was set up and applied. Each single electrode generates a treatment spot of approximately 2 cm2 with a tunable power density of up to 1.4 W/cm2. The surface energy was evaluated by contact angle measurements. After treatment at a low energy density of 1.01 J/cm2, the polar fraction of the surface energy of the investigated polymers was increased by a factor of 3.3 to 132, depending on the polymer materials. It was shown that by applying the presented fittable plasma source, this effect is independent of the surface radius of the polymer sample.

  4. Surface structure and surface kinetics of InN grown by plasma-assisted atomic layer epitaxy: A HREELS study

    SciTech Connect

    Acharya, Ananta R. E-mail: anantaach@gmail.com; Thoms, Brian D.; Nepal, Neeraj; Eddy, Charles R.

    2015-03-15

    The surface bonding configuration and kinetics of hydrogen desorption from InN grown by plasma-assisted atomic layer epitaxy have been investigated. High resolution electron energy loss spectra exhibited loss peaks assigned to a Fuchs–Kliewer surface phonon, N-N and N-H surface species. The surface N-N vibrations are attributed to surface defects. The observation of N-H but no In-H surface species suggested N-terminated InN. Isothermal desorption data were best fit by the first-order desorption kinetics with an activation energy of (0.88 ± 0.06) eV and pre-exponential factor of (1.5 ± 0.5) × 10{sup 5 }s{sup −1}.

  5. Simulation calculations of physical sputtering and reflection coefficient of plasma-irradiated carbon surface

    NASA Astrophysics Data System (ADS)

    Kawamura, T.; Ono, T.; Yamamura, Y.

    1995-04-01

    Physical sputtering yields from the carbon surface irradiated by the boundary plasma are obtained with the use of the Monte Carlo simulation code ACAT. The yields are calculated for many random initial energy and angle values of incident protons or deuterons with a Maxwellian velocity distribution, and then averaged. Here the temperature of the boundary plasma, the sheath potential and the angle δ between the magnetic field line and the surface normal are taken into account. A new fitting formula for an arrangement of the numerical data of sputtering yield is introduced, in which six fitting parameters are determined from the numerical results and listed. These results provide a way to estimate the erosion of carbon materials irradiated by the boundary plasma. The particle reflection coefficients for deuterons and their neutrals from a carbon surface are also calculated by the same code and presented together with, for comparison, that for the case of monoenergetic normal incidence.

  6. Inductively Coupling Plasma (ICP) Treatment of Propylene (PP) Surface and Adhesion Improvement

    NASA Astrophysics Data System (ADS)

    Liu, Yenchun; Fu, Yenpei

    2009-12-01

    Study on increasing the roughness of the polymer substrate surface to enhance the adhesion with the copper layer in an inductively coupling plasma (ICP) process was carried out. The microstructure of the polymer substrate surfaces, which were exposed to different kinds of plasma treatment, was identified by scanning electron microscopy(SEM) analysis, peel strength of the copper coating and water surface contact angle. The adhesion of the substrate was largely enhanced by plasma treatment and the copper deposited coating reached a value of 7.68 kgf/m in verifying the adhesion of the copper coating with polymer material. The quality of the line/space 50/50 μm produced in the laboratory was examined by the pressure cooker test and proved to meet the requirement.

  7. Apparatus and method for atmospheric pressure reactive atom plasma processing for shaping of damage free surfaces

    DOEpatents

    Carr; Jeffrey W.

    2009-03-31

    Fabrication apparatus and methods are disclosed for shaping and finishing difficult materials with no subsurface damage. The apparatus and methods use an atmospheric pressure mixed gas plasma discharge as a sub-aperture polisher of, for example, fused silica and single crystal silicon, silicon carbide and other materials. In one example, workpiece material is removed at the atomic level through reaction with fluorine atoms. In this example, these reactive species are produced by a noble gas plasma from trace constituent fluorocarbons or other fluorine containing gases added to the host argon matrix. The products of the reaction are gas phase compounds that flow from the surface of the workpiece, exposing fresh material to the etchant without condensation and redeposition on the newly created surface. The discharge provides a stable and predictable distribution of reactive species permitting the generation of a predetermined surface by translating the plasma across the workpiece along a calculated path.

  8. PLASMA TREATMENT OF BULK Nb SURFACE IN THE Ar/Cl2 DISCHARGE

    SciTech Connect

    Marija Raskovic; H. Phillips; Anne-Marie Valente

    2008-02-12

    The preparation of the cavity walls has been one of the major challenges in the superconducting radio-frequency (SRF) accelerator technology. Therefore, constant research and development effort is devoted to develop surface preparation processes that will improve roughness and lower the level of impurities, like hydrogen or oxygen, embedded in bulk Nb, having in the same time reasonable etching rates. Plasma based surface modification provides an excellent opportunity to achieve these goals. We present Ar/Cl2 discharge treatment of bulk Nb where we achieved etching rates comparable to the rates obtained with the electropolishing method without introducing impurities in Nb. The current experiments were performed on disk shaped Nb samples, exposed to plasma produced in a microwave discharge system. Surface composition and topology measurements were carried out before and after plasma treatment. Upon determining optimal experimental conditions on disk shaped samples, we will apply the same procedure on the single cell cavities, pursuing improvement of their RF performance.

  9. Lunar dusty plasma: A result of interaction of the solar wind flux and ultraviolet radiation with the lunar surface

    NASA Astrophysics Data System (ADS)

    Lisin, E. A.; Tarakanov, V. P.; Popel, S. I.; Petrov, O. F.

    2015-11-01

    One of the main problems of future missions to the Moon is associated with lunar dust. Solar wind flux and ultraviolet radiation interact with the lunar surface. As a result, there is a substantial surface change and a near-surface plasma sheath. Dust particles from the lunar regolith, which turned in this plasma because of any mechanical processes, can levitate above the surface, forming dust clouds. In preparing of the space experiments “Luna-Glob” and “Luna-Resource” particle-in-cell calculations of the near-surface plasma sheath parameters are carried out. Here we present some new results of particle-in-cell simulation of the plasma sheath formed near the surface of the moon as a result of interaction of the solar wind and ultraviolet radiation with the lunar surface. The conditions of charging and stable levitation of dust particles in plasma above the lunar surface are also considered.

  10. Synthesis of antibacterial surfaces by plasma grafting of zinc oxide based nanocomposites onto polypropylene.

    PubMed

    de Rancourt, Yoann; Couturaud, Benoit; Mas, André; Robin, Jean Jacques

    2013-07-15

    Antibacterial polymer surfaces were designed using ZnO nanoparticles as a bactericide. Mineral encapsulated nanoparticles were grafted onto activated polymer surfaces through their shells. Polypropylene (PP) surfaces were treated using an innovative process coupling core-shell technology and plasma grafting, well-known techniques commonly used to obtain active surfaces for biomedical applications. First, ZnO nanoparticles were encapsulated by (co)polymers: poly(acrylic acid) (PAA) or a poly(methyl methacrylate-co-methacrylic acid) copolymer [P(MMA-MA)]. Second, PP substrates were activated using plasma treatment. Finally, plasma-treated surfaces were immersed in solutions containing the encapsulated nanoparticles dispersed in an organic solvent and allowed to graft onto it. The presence of nanoparticles on the substrates was demonstrated using Fourier-Transform Infrared Spectroscopy (FTIR) analysis, Scanning Electron Microspcopy (SEM)/Energy-Dispersive X-ray (EDX), and Atomic Force Microscopy (AFM) studies. Indeed, the ZnO-functionalized substrates exhibited an antibacterial response in Escherichia coli adhesion tests. Moreover, this study revealed that, surprisingly, native ZnO nanoparticles without any previous functionalization could be directly grafted onto polymeric surfaces through plasma activation. The antibacterial activity of the resulting sample was shown to be comparable to that of the other samples.

  11. Surface oxidation of GaN(0001): Nitrogen plasma-assisted cleaning for ultrahigh vacuum applications

    SciTech Connect

    Gangopadhyay, Subhashis; Schmidt, Thomas Kruse, Carsten; Figge, Stephan; Hommel, Detlef; Falta, Jens

    2014-09-01

    The cleaning of metal-organic vapor-phase epitaxial GaN(0001) template layers grown on sapphire has been investigated. Different procedures, performed under ultrahigh vacuum conditions, including degassing and exposure to active nitrogen from a radio frequency nitrogen plasma source have been compared. For this purpose, x-ray photoelectron spectroscopy, reflection high-energy electron diffraction, and scanning tunneling microscopy have been employed in order to assess chemical as well as structural and morphological surface properties. Initial degassing at 600 °C under ultrahigh vacuum conditions only partially eliminates the surface contaminants. In contrast to plasma assisted nitrogen cleaning at temperatures as low as 300 °C, active-nitrogen exposure at temperatures as high as 700 °C removes the majority of oxide species from the surface. However, extended high-temperature active-nitrogen cleaning leads to severe surface roughening. Optimum results regarding both the removal of surface oxides as well as the surface structural and morphological quality have been achieved for a combination of initial low-temperature plasma-assisted cleaning, followed by a rapid nitrogen plasma-assisted cleaning at high temperature.

  12. Simulation studies on the evolution of gallium nitride on a liquid gallium surface under plasma bombardment.

    PubMed

    Vasquez, M R; Flauta, R E; Wada, M

    2008-02-01

    Monte Carlo simulations were conducted to study the formation of gallium-nitride (GaN) layer on liquid gallium (Ga) sputtering target immersed in nitrogen (N(2)) plasma. In the simulation model, N ions were assumed to possess energy equal to the bias voltage applied to the sputtering target with respect to the plasma. The results showed the surface morphology of GaN changed from a relatively smooth GaN on Ga surface at 50 eV N ion energy to a rough surface with GaN dendrites on liquid Ga at 500 eV ion energy. Further increase in N ion energy up to 1 keV resulted in smaller density of GaN dendrites on surface. Increasing surface coverage of Ga by GaN substantially reduced the sputtering yield of Ga from the target. These simulation results were correlated with previously reported experimental observations on liquid Ga surface immersed in the nitrogen plasma of a plasma-sputter-type ion source.

  13. Electric breakdowns of the "plasma capacitors" occurs on insulation coating of the ISS surface

    NASA Astrophysics Data System (ADS)

    Homin, Taras; Korsun, Anatolii

    High electric fields and currents are occurred in the spacecrafts plasma environment by onboard electric generators. Thus the high voltage solar array (SA) of the American segment of International Space Station (ISS) generates potential 160 V. Its negative pole is shorted to the frames of all the ISS segments. There is electric current between the SA and the frame through the plasma environment, i.e. electric discharge occurs. As a result a potential drop exists between the frames of all the ISS segments and the environmental plasma [1], which is cathode drop potential varphi _{c} defined. When ISS orbiting, the φc varies greatly in the range 0-100 V. A large area of the ISS frames and SA surface is coated with a thin dielectric film. Because of cathode drop potential the frame surfaces accumulate ion charges and the SA surfaces accumulate electron charges. These surfaces become plasma capacitors, which accumulate much charge and energy. Micrometeorite impacts or buildup of potential drop in excess of breakdown threshold varphi_{b} (varphi _{c} > varphi _{b} = 60 V) may cause breakdowns of these capacitors. Following a breakdown, the charge collected at the surfaces disperses and transforms into a layer of dense plasma [2]. This plasma environment of the spacecraft produces great pulsed electric fields E at the frame surfaces as well as heavy currents between construction elements which in turn induce great magnetic fields H. Therefore the conductive frame and the environmental plasma is plasma inductors. We have calculated that the densities of these pulsing and high-frequency fields E and H generated in the plasma environment of the spacecraft may exceed values hazardous to human. Besides, these fields must induce large electromagnetic impulses in the space-suit and in the power supply and control circuits of onboard systems. During astronaut’s space-suit activity, these fields will penetrate the space-suit and the human body with possible hazardous effects