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Sample records for temperature plasma enhanced

  1. Low temperature growth of gallium oxide thin films via plasma enhanced atomic layer deposition

    NARCIS (Netherlands)

    O'Donoghue, R.; Rechmann, J.; Aghaee, M.; Rogalla, D.; Becker, H.-W.; Creatore, M.; Wieck, A.D.; Devi, A.P.K.

    2017-01-01

    Herein we describe an efficient low temperature (60–160 °C) plasma enhanced atomic layer deposition (PEALD) process for gallium oxide (Ga2O3) thin films using hexakis(dimethylamido)digallium [Ga(NMe2)3]2 with oxygen (O2) plasma on Si(100). The use of O2 plasma was found to have a significant

  2. Room-temperature plasma-enhanced chemical vapor deposition of SiOCH films using tetraethoxysilane

    International Nuclear Information System (INIS)

    Yamaoka, K.; Yoshizako, Y.; Kato, H.; Tsukiyama, D.; Terai, Y.; Fujiwara, Y.

    2006-01-01

    Carbon-doped silicon oxide (SiOCH) thin films were deposited by room-temperature plasma-enhanced chemical vapor deposition (PECVD) using tetraethoxysilane (TEOS). The deposition rate and composition of the films strongly depended on radio frequency (RF) power. The films deposited at low RF power contained more CH n groups. The SiOCH films showed high etch rate and low refractive index in proportion to the carbon composition. The deposition with low plasma density and low substrate temperature is effective for SiOCH growth by PECVD using TEOS

  3. Electrical transport properties of graphene nanowalls grown at low temperature using plasma enhanced chemical vapor deposition

    Science.gov (United States)

    Zhao, Rong; Ahktar, Meysam; Alruqi, Adel; Dharmasena, Ruchira; Jasinski, Jacek B.; Thantirige, Rukshan M.; Sumanasekera, Gamini U.

    2017-05-01

    In this work, we report the electrical transport properties of uniform and vertically oriented graphene (graphene nanowalls) directly synthesized on multiple substrates including glass, Si/SiO2 wafers, and copper foils using radio-frequency plasma enhanced chemical vapor deposition (PECVD) with methane (CH4) as the precursor at relatively low temperatures. The temperature for optimum growth was established with the aid of transmission electron microscopy, scanning electron microscopy, and Raman spectroscopy. This approach offers means for low-cost graphene nanowalls growth on an arbitrary substrate with the added advantage of transfer-free device fabrication. The temperature dependence of the electrical transport properties (resistivity and thermopower) were studied in the temperature range, 30-300 K and analyzed with a combination of 2D-variable range hopping (VRH) and thermally activated (TA) conduction mechanisms. An anomalous temperature dependence of the thermopower was observed for all the samples and explained with a combination of a diffusion term having a linear temperature dependence plus a term with an inverse temperature dependence.

  4. Effects of the instability enhanced friction on relative ion densities in a two-ion species low-temperature plasma

    Science.gov (United States)

    Vukovic, Mirko

    2011-10-01

    The instability enhanced friction theory of Baalrud & Hegna (Phys. Plasmas 18, 023505 (2011)) predicts that for comparable ion densities the ions nearly reach a common velocity near the sheath edge in a low temperature plasma. The theory was experimentally confirmed by Yip, Hershkowitz, & Severn (Phys. Rev. Letters 104, 225003 (2010)). We will explore the effects of the theory on relative ion densities in a numerical simulation of an Ar/Xe plasma. Results for a 0D plasma model (Lieberman, Lichtenberg, Principles of Plasma Discharges and Materials Processing, 2005) will be presented.

  5. Room temperature synthesis of porous SiO2 thin films by plasma enhanced chemical vapor deposition

    OpenAIRE

    Barranco Quero, Ángel; Cotrino Bautista, José; Yubero Valencia, Francisco; Espinós, J. P.; Rodríguez González-Elipe, Agustín

    2004-01-01

    Synthesis of porous SiO2 thin films in room temperature was carried out using plasma enhanced chemical vapor deposition (CVD) in an electron cyclotron resonance microwave reactor with a downstream configuration.The gas adsorption properties and the type of porosity of the SiO2 thin films were assessed by adsorption isotherms of toluene at room temperature.The method could also permit the tailoring synthesis of thin films when both composition and porosity can be simultaneously and independent...

  6. Foundations of low-temperature plasma enhanced materials synthesis and etching

    Science.gov (United States)

    Oehrlein, Gottlieb S.; Hamaguchi, Satoshi

    2018-02-01

    Low temperature plasma (LTP)-based synthesis of advanced materials has played a transformational role in multiple industries, including the semiconductor industry, liquid crystal displays, coatings and renewable energy. Similarly, the plasma-based transfer of lithographically defined resist patterns into other materials, e.g. silicon, SiO2, Si3N4 and other electronic materials, has led to the production of nanometer scale devices that are the basis of the information technology, microsystems, and many other technologies based on patterned films or substrates. In this article we review the scientific foundations of both LTP-based materials synthesis at low substrate temperature and LTP-based isotropic and directional etching used to transfer lithographically produced resist patterns into underlying materials. We cover the fundamental principles that are the basis of successful application of the LTP techniques to technological uses and provide an understanding of technological factors that may control or limit material synthesis or surface processing with the use of LTP. We precede these sections with a general discussion of plasma surface interactions, the LTP-generated particle fluxes including electrons, ions, radicals, excited neutrals and photons that simultaneously contact and modify surfaces. The surfaces can be in the line of sight of the discharge or hidden from direct interaction for structured substrates. All parts of the article are extensively referenced, which is intended to help the reader study the topics discussed here in more detail.

  7. LiF enhanced nucleation of the low temperature microcrystalline silicon prepared by plasma enhanced chemical vapour deposition

    Czech Academy of Sciences Publication Activity Database

    Stuchlík, Jiří; Ledinský, Martin; Honda, Shinya; Drbohlav, Ivo; Mates, Tomáš; Fejfar, Antonín; Hruška, Karel; Stuchlíková, The-Ha; Kočka, Jan

    2009-01-01

    Roč. 517, č. 24 (2009), s. 6829-6832 ISSN 0040-6090 R&D Projects: GA AV ČR KAN400100701; GA ČR(CZ) GD202/05/H003; GA MŠk LC510; GA AV ČR IAA1010413 Institutional research plan: CEZ:AV0Z10100521 Keywords : amorphous hydrogenated silicon * atomic force microscopy * plasma-enhanced chemical vapour deposition, * nucleation * Raman scattering * lithium fluoride Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.727, year: 2009

  8. High temperature divertor plasma operation

    International Nuclear Information System (INIS)

    Ohyabu, Nobuyoshi.

    1991-02-01

    High temperature divertor plasma operation has been proposed, which is expected to enhance the core energy confinement and eliminates the heat removal problem. In this approach, the heat flux is guided through divertor channel to a remote area with a large target surface, resulting in low heat load on the target plate. This allows pumping of the particles escaping from the core and hence maintaining of the high divertor temperature, which is comparable to the core temperature. The energy confinement is then determined by the diffusion coefficient of the core plasma, which has been observed to be much lower than the thermal diffusivity. (author)

  9. Low-temperature SiON films deposited by plasma-enhanced atomic layer deposition method using activated silicon precursor

    Energy Technology Data Exchange (ETDEWEB)

    Suh, Sungin; Kim, Jun-Rae; Kim, Seongkyung; Hwang, Cheol Seong; Kim, Hyeong Joon, E-mail: thinfilm@snu.ac.kr [Department of Materials Science and Engineering with Inter-University Semiconductor Research Center (ISRC), Seoul National University, 599 Gwanak-ro, Gwanak-gu, Seoul 08826 (Korea, Republic of); Ryu, Seung Wook, E-mail: tazryu78@gmail.com [Department of Electrical Engineering, Stanford University, Stanford, California 94305-2311 (United States); Cho, Seongjae [Department of Electronic Engineering and New Technology Component & Material Research Center (NCMRC), Gachon University, Seongnam-si, Gyeonggi-do 13120 (Korea, Republic of)

    2016-01-15

    It has not been an easy task to deposit SiN at low temperature by conventional plasma-enhanced atomic layer deposition (PE-ALD) since Si organic precursors generally have high activation energy for adsorption of the Si atoms on the Si-N networks. In this work, in order to achieve successful deposition of SiN film at low temperature, the plasma processing steps in the PE-ALD have been modified for easier activation of Si precursors. In this modification, the efficiency of chemisorption of Si precursor has been improved by additional plasma steps after purging of the Si precursor. As the result, the SiN films prepared by the modified PE-ALD processes demonstrated higher purity of Si and N atoms with unwanted impurities such as C and O having below 10 at. % and Si-rich films could be formed consequently. Also, a very high step coverage ratio of 97% was obtained. Furthermore, the process-optimized SiN film showed a permissible charge-trapping capability with a wide memory window of 3.1 V when a capacitor structure was fabricated and measured with an insertion of the SiN film as the charge-trap layer. The modified PE-ALD process using the activated Si precursor would be one of the most practical and promising solutions for SiN deposition with lower thermal budget and higher cost-effectiveness.

  10. Low Temperature Plasma Medicine

    Science.gov (United States)

    Graves, David

    2013-10-01

    Ionized gas plasmas near room temperature are used in a remarkable number of technological applications mainly because they are extraordinarily efficient at exploiting electrical power for useful chemical and material transformations near room temperature. In this tutorial address, I will focus on the newest area of low temperature ionized gas plasmas (LTP), in this case operating under atmospheric pressure conditions, in which the temperature-sensitive material is living tissue. LTP research directed towards biomedical applications such as sterilization, surgery, wound healing and anti-cancer therapy has seen remarkable growth in the last 3-5 years, but the mechanisms responsible for the biomedical effects have remained mysterious. It is known that LTP readily create reactive oxygen species (ROS) and reactive nitrogen species (RNS). ROS and RNS (or RONS), in addition to a suite of other radical and non-radical reactive species, are essential actors in an important sub-field of aerobic biology termed ``redox'' (or oxidation-reduction) biology. I will review the evidence suggesting that RONS generated by plasmas are responsible for their observed therapeutic effects. Other possible bio-active mechanisms include electric fields, charges and photons. It is common in LTP applications that synergies between different mechanisms can play a role and I will review the evidence for synergies in plasma biomedicine. Finally, I will address the challenges and opportunities for plasma physicists to enter this novel, multidisciplinary field.

  11. Low-temperature ({<=}200 Degree-Sign C) plasma enhanced atomic layer deposition of dense titanium nitride thin films

    Energy Technology Data Exchange (ETDEWEB)

    Samal, Nigamananda; Du Hui; Luberoff, Russell; Chetry, Krishna; Bubber, Randhir; Hayes, Alan; Devasahayam, Adrian [Veeco Instruments, 1 Terminal Drive, Plainview, New York 11803 (United States)

    2013-01-15

    Titanium nitride (TiN) has been widely used in the semiconductor industry for its diffusion barrier and seed layer properties. However, it has seen limited adoption in other industries in which low temperature (<200 Degree-Sign C) deposition is a requirement. Examples of applications which require low temperature deposition are seed layers for magnetic materials in the data storage (DS) industry and seed and diffusion barrier layers for through-silicon-vias (TSV) in the MEMS industry. This paper describes a low temperature TiN process with appropriate electrical, chemical, and structural properties based on plasma enhanced atomic layer deposition method that is suitable for the DS and MEMS industries. It uses tetrakis-(dimethylamino)-titanium as an organometallic precursor and hydrogen (H{sub 2}) as co-reactant. This process was developed in a Veeco NEXUS Trade-Mark-Sign chemical vapor deposition tool. The tool uses a substrate rf-biased configuration with a grounded gas shower head. In this paper, the complimentary and self-limiting character of this process is demonstrated. The effects of key processing parameters including temperature, pulse time, and plasma power are investigated in terms of growth rate, stress, crystal morphology, chemical, electrical, and optical properties. Stoichiometric thin films with growth rates of 0.4-0.5 A/cycle were achieved. Low electrical resistivity (<300 {mu}{Omega} cm), high mass density (>4 g/cm{sup 3}), low stress (<250 MPa), and >85% step coverage for aspect ratio of 10:1 were realized. Wet chemical etch data show robust chemical stability of the film. The properties of the film have been optimized to satisfy industrial viability as a Ruthenium (Ru) preseed liner in potential data storage and TSV applications.

  12. SiO2 films deposited on silicon at low temperature by plasma-enhanced decomposition of hexamethyldisilazane: Defect characterization

    International Nuclear Information System (INIS)

    Croci, S.; Pecheur, A.; Autran, J.L.; Vedda, A.; Caccavale, F.; Martini, M.; Spinolo, G.

    2001-01-01

    Silicon dioxide films have been deposited by plasma-enhanced chemical vapor deposition at low substrate temperature (50 deg. C) in a parallel-plate reactor using hexamethyldisilazane (HMDS), diluted in He, and O 2 as Si and O precursors. The effect of the O 2 /(HMDS+He) flow rate ratio on the oxide properties has been investigated in the range of 0.05-1.25 by means of deposition rate, wet etching rate, secondary ion mass spectrometry, thermally stimulated luminescence, and high frequency capacitance-voltage measurements. Both the deposition rate and the etching rate increase by increasing the O 2 /(HMDS+He) flow rate ratio and reach a constant value at flow rate ratios higher than 0.6. The strong increase and saturation in the deposition rate can be attributed to the impinging oxide atoms flux and to the consumption of silyl radicals at the deposition surface, respectively. The Si/SiO 2 interface state density and the positive fixed charge density are in the range 1x10 11 -1x10 12 eV -1 cm -2 and 6x10 11 -1.5x10 12 C cm -2 , respectively. These concentrations are comparable with literature data concerning SiO 2 films obtained by plasma enhanced chemical vapor deposition at temperatures higher than 200 deg. C using other Si precursors. Moreover, the interface state density decreases while the fixed oxide charge increases by increasing the O 2 /(HMDS+He) flow rate ratio. A correlation has been found between defects monitored by thermally stimulated luminescence and fixed oxide charges. From a comparison with secondary ion mass spectrometry results, the fixed oxide charges can be preliminarily attributed to intrinsic defects

  13. Estimating plasma temperatures

    International Nuclear Information System (INIS)

    Nash, J.K.; Iglesias, C.A.; Chen, M.H.; Rogers, F.J.

    1992-04-01

    Recent laser-produced plasma experiments have relied on spectroscopic comparisons with models to infer plasma temperatures. The models use an experimentally determined value for the matter density as input and treat the temperature as a free parameter to obtain a best fit to the experimental absorption spectrum. However, uncertainties in the ionization balance theories lead to inferred temperatures that are model dependent. We report results of a new approach which combines high=quality atomic data with an ionization balance obtained from systematic expansions of the grand canonical ensemble. The latter avoids the ad hoc cutoffs required in free energy minimization schemes and includes Coulomb corrections usually neglected in other models. Comparisons to experimental spectra show excellent agreement

  14. Catalyst-free growth and tailoring morphology of zinc oxide nanostructures by plasma-enhanced deposition at low temperature

    Energy Technology Data Exchange (ETDEWEB)

    Chen, W. Z. [Quanzhou Normal University, Key Laboratory of Information Functional Material for Fujian Higher Education, College of Physics & Information Engineering (China); Wang, B. B. [Chongqing University of Technology, College of Chemical Engineering (China); Qu, Y. Z.; Huang, X. [Xiamen University, College of Energy, Xiang’an Campus (China); Ostrikov, K. [Queensland University of Technology, School of Chemistry, Physics and Mechanical Engineering (Australia); Levchenko, I.; Xu, S. [Nanyang Technological University, Plasma Sources and Applications Centre, National Institute of Education (Singapore); Cheng, Q. J., E-mail: qijin.cheng@xmu.edu.cn [Xiamen University, College of Energy, Xiang’an Campus (China)

    2017-03-15

    ZnO nanostructures were grown under different deposition conditions from Zn films pre-deposited onto Si substrates in O{sub 2}-Ar plasma, ignited in an advanced custom-designed plasma-enhanced horizontal tube furnace deposition system. The morphology and structure of the synthesized ZnO nanostructures were systematically and extensively investigated by scanning and transmission electron microscopy, Raman spectroscopy, and atomic force microscopy. It is shown that the morphology of ZnO nanostructures changes from the hybrid ZnO/nanoparticle and nanorod system to the mixture of ZnO nanosheets and nanorods when the growth temperature increases, and the density of ZnO nanorods increases with the increase of oxygen flow rate. The formation of ZnO nanostructures was explained in terms of motion of Zn atoms on the Zn nanoparticle surfaces, and to the local melting of Zn nanoparticles or nanosheets. Moreover, the photoluminescence properties of ZnO nanostructures were studied, and it was revealed that the photoluminescence spectrum features two strong ultraviolet bands at about 378 and 399 nm and a series of weak blue bands within a range of 440–484 nm, related to the emissions of free excitons, near-band edge, and defects of ZnO nanostructures. The obtained results enrich our knowledge on the synthesis of ZnO-based nanostructures and contribute to the development of ZnO-based optoelectronic devices.

  15. Catalyst-free growth and tailoring morphology of zinc oxide nanostructures by plasma-enhanced deposition at low temperature

    International Nuclear Information System (INIS)

    Chen, W. Z.; Wang, B. B.; Qu, Y. Z.; Huang, X.; Ostrikov, K.; Levchenko, I.; Xu, S.; Cheng, Q. J.

    2017-01-01

    ZnO nanostructures were grown under different deposition conditions from Zn films pre-deposited onto Si substrates in O 2 -Ar plasma, ignited in an advanced custom-designed plasma-enhanced horizontal tube furnace deposition system. The morphology and structure of the synthesized ZnO nanostructures were systematically and extensively investigated by scanning and transmission electron microscopy, Raman spectroscopy, and atomic force microscopy. It is shown that the morphology of ZnO nanostructures changes from the hybrid ZnO/nanoparticle and nanorod system to the mixture of ZnO nanosheets and nanorods when the growth temperature increases, and the density of ZnO nanorods increases with the increase of oxygen flow rate. The formation of ZnO nanostructures was explained in terms of motion of Zn atoms on the Zn nanoparticle surfaces, and to the local melting of Zn nanoparticles or nanosheets. Moreover, the photoluminescence properties of ZnO nanostructures were studied, and it was revealed that the photoluminescence spectrum features two strong ultraviolet bands at about 378 and 399 nm and a series of weak blue bands within a range of 440–484 nm, related to the emissions of free excitons, near-band edge, and defects of ZnO nanostructures. The obtained results enrich our knowledge on the synthesis of ZnO-based nanostructures and contribute to the development of ZnO-based optoelectronic devices.

  16. Low-temperature plasma-enhanced atomic layer deposition of 2-D MoS2 : Large area, thickness control and tuneable morphology

    NARCIS (Netherlands)

    Sharma, A.; Verheijen, M.A.; Wu, L.; Karwal, S.; Vandalon, V.; Knoops, H.C.M.; Sundaram, R.S.; Hofmann, J.P.; Kessels, W.M.M.; Bol, A.A.

    2018-01-01

    Low-temperature controllable synthesis of monolayer-to-multilayer thick MoS2 with tuneable morphology is demonstrated by using plasma enhanced atomic layer deposition (PEALD). The characteristic self-limiting ALD growth with a growth-per-cycle of 0.1 nm per cycle and digital thickness control down

  17. Low-temperature synthesis of diamond films by photoemission-assisted plasma-enhanced chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kawata, Mayuri, E-mail: kawata@mail.tagen.tohoku.ac.jp; Ojiro, Yoshihiro; Ogawa, Shuichi; Takakuwa, Yuji [Institute of Multidisciplinary Research for Advanced Materials, Tohoku University, 2-1-1 Katahira, Aoba-ku, Sendai 980-8577 (Japan); Masuzawa, Tomoaki; Okano, Ken [International Christian University, 3-10-2 Osawa, Mitaka 181-8585 (Japan)

    2014-03-15

    Photoemission-assisted plasma-enhanced chemical vapor deposition (PA-PECVD), a process in which photoelectrons emitted from a substrate irradiated with ultraviolet light are utilized as a trigger for DC discharge, was investigated in this study; specifically, the DC discharge characteristics of PA-PECVD were examined for an Si substrate deposited in advance through hot-filament chemical vapor deposition with a nitrogen-doped diamond layer of thickness ∼1 μm. Using a commercially available Xe excimer lamp (hν = 7.2 eV) to illuminate the diamond surface with and without hydrogen termination, the photocurrents were found to be 3.17 × 10{sup 12} and 2.11 × 10{sup 11} electrons/cm{sup 2}/s, respectively. The 15-fold increase in photocurrent was ascribed to negative electron affinity (NEA) caused by hydrogen termination on the diamond surfaces. The DC discharge characteristics revealed that a transition bias voltage from a Townsend-to-glow discharge was considerably decreased because of NEA (from 490 to 373 V for H{sub 2} gas and from 330 to 200 V for Ar gas), enabling a reduction in electric power consumption needed to synthesize diamond films through PA-PECVD. In fact, the authors have succeeded in growing high-quality diamond films of area 2.0 cm{sup 2} at 540 °C with a discharge power of only 1.8 W, plasma voltage of 156.4 V, and discharge current of 11.7 mA under the glow discharge of CH{sub 4}/H{sub 2}/Ar mixed gases. In addition to having only negligible amounts of graphite and amorphous carbon, the diamond films exhibit a relatively high diamond growth rate of 0.5 μm/h at temperatures as low as 540 °C, which is attributed to Ar{sup +} ions impinging on the diamond surface, and causing the removal of hydrogen atoms from the surface through sputtering. This process leads to enhanced CH{sub x} radical adsorption, because the sample was applied with a negative potential to accelerate photoelectrons in PA-PECVD.

  18. High-temperature plasma physics

    International Nuclear Information System (INIS)

    Furth, H.P.

    1988-03-01

    Both magnetic and inertial confinement research are entering the plasma parameter range of fusion reactor interest. This paper reviews the individual and common technical problems of these two approaches to the generation of thermonuclear plasmas, and describes some related applications of high-temperature plasma physics

  19. Containment of high temperature plasmas

    International Nuclear Information System (INIS)

    Bass, R.W.; Ferguson, H.R.P.; Fletcher, H. Jr.; Gardner, J.; Harrison, B.K.; Larsen, K.M.

    1973-01-01

    Apparatus is described for confining a high temperature plasma which comprises: 1) envelope means shaped to form a toroidal hollow chamber containing a plasma, 2) magnetic field line generating means for confining the plasma in a smooth toroidal shape without cusps. (R.L.)

  20. Low temperature plasma-enhanced atomic layer deposition of thin vanadium nitride layers for copper diffusion barriers

    Energy Technology Data Exchange (ETDEWEB)

    Rampelberg, Geert; Devloo-Casier, Kilian; Deduytsche, Davy; Detavernier, Christophe [Department of Solid State Sciences, Ghent University, Krijgslaan 281/S1, B-9000 Ghent (Belgium); Schaekers, Marc [IMEC, Kapeldreef 75, B-3001 Leuven (Belgium); Blasco, Nicolas [Air Liquide Electronics US, L.P., 46401 Landing Parkway, Fremont, California 94538 (United States)

    2013-03-18

    Thin vanadium nitride (VN) layers were grown by atomic layer deposition using tetrakis(ethylmethylamino)vanadium and NH{sub 3} plasma at deposition temperatures between 70 Degree-Sign C and 150 Degree-Sign C on silicon substrates and polymer foil. X-ray photoelectron spectroscopy revealed a composition close to stoichiometric VN, while x-ray diffraction showed the {delta}-VN crystal structure. The resistivity was as low as 200 {mu}{Omega} cm for the as deposited films and further reduced to 143 {mu}{Omega} cm and 93 {mu}{Omega} cm by annealing in N{sub 2} and H{sub 2}/He/N{sub 2}, respectively. A 5 nm VN layer proved to be effective as a diffusion barrier for copper up to a temperature of 720 Degree-Sign C.

  1. Enhanced TiC/SiC Ohmic contacts by ECR hydrogen plasma pretreatment and low-temperature post-annealing

    International Nuclear Information System (INIS)

    Liu, Bingbing; Qin, Fuwen; Wang, Dejun

    2015-01-01

    Highlights: • Low-temperature ECR microwave hydrogen plasma were pretreated for moderately doped (1 × 10"1"8 cm"−"3) SiC surfaces. • The relationship among Ohmic properties, the SiC surface properties and TiC/SiC interface properties were established. • Interface band structures were analyzed to elucidate the mechanism by which the Ohmic contacts were formed. - Abstract: We proposed an electronic cyclotron resonance (ECR) microwave hydrogen plasma pretreatment (HPT) for moderately doped (1 × 10"1"8 cm"−"3) SiC surfaces and formed ideal TiC/SiC Ohmic contacts with significantly low contact resistivity (1.5 × 10"−"5 Ω cm"2) after low-temperature annealing (600 °C). This is achieved by reducing barrier height at TiC/SiC interface because of the release of pinned Fermi level by surface flattening and SiC surface states reduction after HPT, as well as the generation of donor-type carbon vacancies, which reduced the depletion-layer width for electron tunneling after annealing. Interface band structures were analyzed to elucidate the mechanism of Ohmic contact formations.

  2. Characteristics of SiOx-containing hard film prepared by low temperature plasma enhanced chemical vapor deposition using hexamethyldisilazane or vinyltrimethylsilane and post oxygen plasma treatment

    Energy Technology Data Exchange (ETDEWEB)

    Wei, Yi-Syuan; Liu, Wan-Yu; Wu, Hsin-Ming [Department of Materials Engineering, Tatung University, Taipei, 104, Taiwan (China); Chen, Ko-Shao, E-mail: kschen@ttu.edu.tw [Department of Materials Engineering, Tatung University, Taipei, 104, Taiwan (China); Cech, Vladimir [Institute of Materials Chemistry, Brno University of Technology (Czech Republic)

    2017-03-01

    This study, monomers of hexamethyldisilazane (HMDSZ) and vinyltrimethylsilane (VTMS) were respectively used to deposit on the surface of polyethylene terephthalate (PET) substrate by plasma enhanced chemical vapor deposition. Oxygen plasma treatment follows the HMDSZ and VTMS deposition to produce a hydrophilic surface film on the deposited surface. Time for HMDSZ and VTMS plasma deposition was changed to investigate its influences on water contact angle, deposited film thickness, refractive index, and friction coefficient properties. The surface morphologies of the processed samples were observed by scanning electron microscope and their chemical compositions were measured by X-ray photoelectron spectroscopy. At 550 nm wavelength, the optical transmittance of PET after the HMDSZ treatment decreases from 89% to 83%, but increases from 89% to 95% for the VTMS treatment. With increase in HMDSZ and VTMS deposition times, the film thickness increases and the refractive index decreases. Result revealed by XPS, SiO{sub 2} film is formed on the sample surface after the O{sub 2} plasma treatment. The film adhesion capability by the HMDSZ+O{sub 2} and VTMS+O{sub 2} treatment was stronger than that by the HMDSZ and VTMS treatment only. The SiOx films produced by HMDSZ+O{sub 2} and VTMS+O{sub 2} treatment can increase the film hardness and improve light transmittance. - Highlights: • With increase in HMDSZ and VTMS deposition times, the film thickness increases and the refractive index decreases. • The optical transmittance of PET after the VTMS treatment increases from 89% to 95%. • The SiO{sub 2} films deposited by HMDSZ+O{sub 2} and VTMS+O{sub 2} plasma can increase the film hardness and improve light transmittance. • It is expected that they can be applied to the optical transmittance protective film on plastic substrate in the future.

  3. Bipolar resistive switching characteristics of low temperature grown ZnO thin films by plasma-enhanced atomic layer deposition

    International Nuclear Information System (INIS)

    Zhang Jian; Yang Hui; Zhang Qilong; Dong Shurong; Luo, J. K.

    2013-01-01

    ZnO films deposited by plasma-enhanced atomic layer deposition (PEALD) have been used to investigate resistive memory behavior. The bipolar resistance switching properties were observed in the Al/PEALD-ZnO/Pt devices. The resistance ratio for the high and low resistance states (HRS/LRS) is more than 10 3 , better than ZnO devices deposited by other methods. The dominant conduction mechanisms of HRS and LRS are trap-controlled space charge limited current and Ohmic behavior, respectively. The resistive switching behavior is induced upon the formation/disruption of conducting filaments. This study demonstrated that the PEALD-ZnO films have better properties for the application in 3D resistance random access memory.

  4. Spectroscopic ellipsometry characterization of nano-crystalline diamondfilms prepared at various substrate temperatures and pulsed plasma frequencies using microwave plasma enhanced chemical vapor deposition apparatus with linear antenna delivery

    Czech Academy of Sciences Publication Activity Database

    Mistrík, J.; Janíček, P.; Taylor, Andrew; Fendrych, František; Fekete, Ladislav; Jäger, Aleš; Nesládek, M.

    2014-01-01

    Roč. 571, č. 1 (2014), s. 230-237 ISSN 0040-6090 R&D Projects: GA ČR GA13-31783S; GA MŠk(CZ) LM2011026 Grant - others: COST Nano TP(XE) MP0901; OP VK(XE) CZ.1.07/2.3.00/20.0306 Institutional support: RVO:68378271 Keywords : nanocrystalline diamond * thin films * microwave plasma-enhanced chemical vapor deposition * pulsed plasma * low deposition temperature Subject RIV: BM - Solid Matter Physics ; Magnetism Impact factor: 1.759, year: 2014

  5. Synthesis and analysis of silicon nanowire below Si-Au eutectic temperatures using very high frequency plasma enhanced chemical vapor deposition

    International Nuclear Information System (INIS)

    Hamidinezhad, Habib; Wahab, Yussof; Othaman, Zulkafli; Ismail, Abd Khamim

    2011-01-01

    Silicon nanowires (SiNWs) were synthesized from pure silane precursor gas and Au nanoparticles catalyst at below Au-Si eutectic temperature. The SiNWs were grown onto Si (1 1 1) substrates using very high frequency plasma enhanced chemical vapor deposition via a vapor-solid-solid mechanism at temperatures ranging from 363 to 230 deg. C. The morphology of the synthesized SiNWs was characterized by means of field emission scanning electron microscope equipped with energy dispersive X-ray, high resolution transmission electron microscopy, X-ray diffraction technique and Raman spectroscope. Results demonstrated that the SiNWs can be grown at the temperature as low as 250 deg. C. In addition, it was revealed that the grown wires were silicon-crystallized.

  6. Temperature measurements in thermonuclear plasmas

    International Nuclear Information System (INIS)

    Breton, D.

    1958-01-01

    The temperatures needed to produce thermonuclear reactions are of the order of several million degrees Kelvin. Devising methods for measuring such temperatures has been the subject of research in many countries. In order to present the problem clearly and to demonstrate its importance, the author reviews the various conditions which must be fulfilled in order that reactions may be qualified as thermonuclear. The relationship between the temperature and the cross-section of the reactions is studied, and it is shown that the notion of temperature in the plasmas is complex, which leads to a consideration of the temperature of the ions and that of the electrons. None of the methods for the temperature measurements is completely satisfactory because of the hypotheses which must be made, and which are seldom fulfilled during high-intensity discharges in the plasmas. In practice it is necessary to use several methods simultaneously. (author) [fr

  7. CONFINEMENT OF HIGH TEMPERATURE PLASMA

    Science.gov (United States)

    Koenig, H.R.

    1963-05-01

    The confinement of a high temperature plasma in a stellarator in which the magnetic confinement has tended to shift the plasma from the center of the curved, U-shaped end loops is described. Magnetic means are provided for counteracting this tendency of the plasma to be shifted away from the center of the end loops, and in one embodiment this magnetic means is a longitudinally extending magnetic field such as is provided by two sets of parallel conductors bent to follow the U-shaped curvature of the end loops and energized oppositely on the inside and outside of this curvature. (AEC)

  8. A Method to Construct Plasma with Nonlinear Density Enhancement Effect in Multiple Internal Inductively Coupled Plasmas

    International Nuclear Information System (INIS)

    Chen Zhipeng; Li Hong; Liu Qiuyan; Luo Chen; Xie Jinlin; Liu Wandong

    2011-01-01

    A method is proposed to built up plasma based on a nonlinear enhancement phenomenon of plasma density with discharge by multiple internal antennas simultaneously. It turns out that the plasma density under multiple sources is higher than the linear summation of the density under each source. This effect is helpful to reduce the fast exponential decay of plasma density in single internal inductively coupled plasma source and generating a larger-area plasma with multiple internal inductively coupled plasma sources. After a careful study on the balance between the enhancement and the decay of plasma density in experiments, a plasma is built up by four sources, which proves the feasibility of this method. According to the method, more sources and more intensive enhancement effect can be employed to further build up a high-density, large-area plasma for different applications. (low temperature plasma)

  9. Low temperature plasma technology methods and applications

    CERN Document Server

    Chu, Paul K

    2013-01-01

    Written by a team of pioneering scientists from around the world, Low Temperature Plasma Technology: Methods and Applications brings together recent technological advances and research in the rapidly growing field of low temperature plasmas. The book provides a comprehensive overview of related phenomena such as plasma bullets, plasma penetration into biofilms, discharge-mode transition of atmospheric pressure plasmas, and self-organization of microdischarges. It describes relevant technology and diagnostics, including nanosecond pulsed discharge, cavity ringdown spectroscopy, and laser-induce

  10. Arc generators of low-temperature plasma

    International Nuclear Information System (INIS)

    Krolikowski, Cz.; Niewiedzial, R.; Siwiec, J.

    1979-01-01

    This paper is a review of works concerning investigation and use of low-temperature plasma in arc plasma generators made in Electric Power Institute of PP. There are discussed: analytical approach to a problem of volt-current and operational characteristics of DC arc plasma generators, determination of limits of their stable work and possibilities of their use to technological aims. (author)

  11. Kinetics and spectroscopy of low temperature plasmas

    CERN Document Server

    Loureiro, Jorge

    2016-01-01

    This is a comprehensive textbook designed for graduate and advanced undergraduate students. Both authors rely on more than 20 years of teaching experience in renowned Physics Engineering courses to write this book addressing the students’ needs. Kinetics and Spectroscopy of Low Temperature Plasmas derives in a full self-consistent way the electron kinetic theory used to describe low temperature plasmas created in the laboratory with an electrical discharge, and presents the main optical spectroscopic diagnostics used to characterize such plasmas. The chapters with the theoretical contents make use of a deductive approach in which the electron kinetic theory applied to plasmas with basis on the electron Boltzmann equation is derived from the basic concepts of Statistical and Plasma Physics. On the other hand, the main optical spectroscopy diagnostics used to characterize experimentally such plasmas are presented and justified from the point of view of the Atomic and Molecular Physics. Low temperature plasmas...

  12. Low-temperature plasma modelling and simulation

    NARCIS (Netherlands)

    Dijk, van J.

    2011-01-01

    Since its inception in the beginning of the twentieth century, low-temperature plasma science has become a major ¿eld of science. Low-temperature plasma sources and gas discharges are found in domestic, industrial, atmospheric and extra-terrestrial settings. Examples of domestic discharges are those

  13. Measuring brightness temperature distributions of plasma bunches

    International Nuclear Information System (INIS)

    Kirko, V.I.; Stadnichenko, I.A.

    1981-01-01

    The possibility of restoration of brightness temperature distribution along plasma jet on the base of a simple ultra high- speed photography and subsequent photometric treatment is shown. The developed technique has been applied for finding spectral radiation intensity and brightness temperature of plasma jets of a tubular gas-cumulative charge and explosive plasma compressor. The problem of shock wave front has been successfully solved and thus distribution of above parameters beginning from the region preceeding the shock wave has been obtained [ru

  14. Atomic processes in high temperature plasmas

    International Nuclear Information System (INIS)

    Hahn, Y.

    1990-03-01

    Much theoretical and experimental efforts have been expended in recent years to study those atomic processes which are specially relevant to understanding high temperature laboratory plasmas. For magnetically confined fusion plasmas, the temperature range of interest spans from the hundreds of eV at plasma edges to 10 keV at the center of the plasma, where most of the impurity ions are nearly fully ionized. These highly stripped ions interact strongly with electrons in the plasma, leading to further excitation and ionization of the ions, as well as electron capture. Radiations are emitted during these processes, which easily escape to plasma container walls, thus cooling the plasma. One of the dominant modes of radiation emission has been identified with dielectronic recombination. This paper reviews this work

  15. Dense high-temperature plasma transport processes

    International Nuclear Information System (INIS)

    Giniyatova, Sh.G.

    2002-01-01

    In this work the transport processes in dense high-temperature semiclassical plasma are studied on the base of the kinetic equation, where the semiclassical potential was used, in its collision integral. The coefficient of plasma electrical conductivity, viscosity and thermal conductivity were received. There were compared with the other authors' results. The Grad's method was used obtaining of viscosity and thermal coefficients. (author)

  16. Industrial Applications of Low Temperature Plasmas

    International Nuclear Information System (INIS)

    Bardsley, J N

    2001-01-01

    The use of low temperature plasmas in industry is illustrated by the discussion of four applications, to lighting, displays, semiconductor manufacturing and pollution control. The type of plasma required for each application is described and typical materials are identified. The need to understand radical formation, ionization and metastable excitation within the discharge and the importance of surface reactions are stressed

  17. Observation of electron plasma waves in plasma of two-temperature electrons

    International Nuclear Information System (INIS)

    Ikezawa, Shunjiro; Nakamura, Yoshiharu.

    1981-01-01

    Propagation of electron plasma waves in a large and unmagnetized plasma containing two Maxwellian distributions of electrons is studied experimentally. Two kinds of plasma sources which supply electrons of different temperature are used. The temperature ratio is about 3 and the density ratio of hot to cool electrons is varied from 0 to 0.5. A small contamination of hot electrons enhances the Landau damping of the principal mode known as the Bohm-Gross mode. When the density of hot electrons is larger than about 0.2, two modes are observed. The results agree with theoretical dispersion relations when excitation efficiencies of the modes are considered. (author)

  18. The 2017 Plasma Roadmap: Low temperature plasma science and technology

    Science.gov (United States)

    Adamovich, I.; Baalrud, S. D.; Bogaerts, A.; Bruggeman, P. J.; Cappelli, M.; Colombo, V.; Czarnetzki, U.; Ebert, U.; Eden, J. G.; Favia, P.; Graves, D. B.; Hamaguchi, S.; Hieftje, G.; Hori, M.; Kaganovich, I. D.; Kortshagen, U.; Kushner, M. J.; Mason, N. J.; Mazouffre, S.; Mededovic Thagard, S.; Metelmann, H.-R.; Mizuno, A.; Moreau, E.; Murphy, A. B.; Niemira, B. A.; Oehrlein, G. S.; Petrovic, Z. Lj; Pitchford, L. C.; Pu, Y.-K.; Rauf, S.; Sakai, O.; Samukawa, S.; Starikovskaia, S.; Tennyson, J.; Terashima, K.; Turner, M. M.; van de Sanden, M. C. M.; Vardelle, A.

    2017-08-01

    Journal of Physics D: Applied Physics published the first Plasma Roadmap in 2012 consisting of the individual perspectives of 16 leading experts in the various sub-fields of low temperature plasma science and technology. The 2017 Plasma Roadmap is the first update of a planned series of periodic updates of the Plasma Roadmap. The continuously growing interdisciplinary nature of the low temperature plasma field and its equally broad range of applications are making it increasingly difficult to identify major challenges that encompass all of the many sub-fields and applications. This intellectual diversity is ultimately a strength of the field. The current state of the art for the 19 sub-fields addressed in this roadmap demonstrates the enviable track record of the low temperature plasma field in the development of plasmas as an enabling technology for a vast range of technologies that underpin our modern society. At the same time, the many important scientific and technological challenges shared in this roadmap show that the path forward is not only scientifically rich but has the potential to make wide and far reaching contributions to many societal challenges.

  19. The 2017 Plasma Roadmap: Low temperature plasma science and technology

    International Nuclear Information System (INIS)

    Adamovich, I; Baalrud, S D; Bogaerts, A; Bruggeman, P J; Cappelli, M; Colombo, V; Czarnetzki, U; Ebert, U; Eden, J G; Favia, P; Graves, D B; Hamaguchi, S; Hieftje, G; Hori, M

    2017-01-01

    Journal of Physics D: Applied Physics published the first Plasma Roadmap in 2012 consisting of the individual perspectives of 16 leading experts in the various sub-fields of low temperature plasma science and technology. The 2017 Plasma Roadmap is the first update of a planned series of periodic updates of the Plasma Roadmap. The continuously growing interdisciplinary nature of the low temperature plasma field and its equally broad range of applications are making it increasingly difficult to identify major challenges that encompass all of the many sub-fields and applications. This intellectual diversity is ultimately a strength of the field. The current state of the art for the 19 sub-fields addressed in this roadmap demonstrates the enviable track record of the low temperature plasma field in the development of plasmas as an enabling technology for a vast range of technologies that underpin our modern society. At the same time, the many important scientific and technological challenges shared in this roadmap show that the path forward is not only scientifically rich but has the potential to make wide and far reaching contributions to many societal challenges. (topical review)

  20. Technological uses of low temperature plasmas

    International Nuclear Information System (INIS)

    Lawton, J.

    1975-01-01

    Types of low temperature plasma sources considered include; arc discharge, high pressure discharge, low pressure discharge and flame. The problems of uniform heating of a gas are discussed and it is considered that the most reliable technique is the magnetically rotated arc, but expanded discharges of one kind or another are likely to be serious competitors in the future. The uses of low temperature plasma in chemistry and combustion are considered. The potential for plasma chemistry lies with processes in which the reactions occur in the plasma itself or its neighbouring gas phase, including those which require the vaporization of liquefaction of a refractory material and also highly endothermic reactions. The production of thixotropic silica and acetylene are discussed as examples of such reactions. The field of plasma and combustion including; ignition, flame ionization and soot formation, and the MHD generator, is considered. (U.K.)

  1. Enhanced nuclear level decay in hot dense plasmas

    International Nuclear Information System (INIS)

    Gosselin, G.; Morel, P.

    2004-01-01

    A model of nuclear level decay in a plasma environment is described. Nuclear excitation and decay by photon processes, nuclear excitation by electron capture, and decay by internal conversion are taken into account. The electrons in the plasma are described by a relativistic average atom model for the bound electrons and by a relativistic Thomas-Fermi-Dirac model for the free electrons. Nuclear decay of isomeric level may be enhanced through an intermediate level lying above the isomer. An enhanced nuclear decay rate may occur for temperatures far below the excitation energy of the transition to the intermediate level. In most cases, the enhancement factor may reach several decades

  2. Biomedical applications using low temperature plasma technology

    International Nuclear Information System (INIS)

    Dai Xiujuan; Jiang Nan

    2006-01-01

    Low temperature plasma technology and biomedicine are two different subjects, but the combination of the two may play a critical role in modern science and technology. The 21 st century is believed to be a biotechnology century. Plasma technology is becoming a widely used platform for the fabrication of biomaterials and biomedical devices. In this paper some of the technologies used for material surface modification are briefly introduced. Some biomedical applications using plasma technology are described, followed by suggestions as to how a bridge between plasma technology and biomedicine can be built. A pulsed plasma technique that is used for surface functionalization is discussed in detail as an example of this kind of bridge or combination. Finally, it is pointed out that the combination of biomedical and plasma technology will be an important development for revolutionary 21st century technologies that requires different experts from different fields to work together. (authors)

  3. Low-temperature formation of crystalline Si:H/Ge:H heterostructures by plasma-enhanced CVD in combination with Ni-nanodots seeding nucleation

    Science.gov (United States)

    Lu, Yimin; Makihara, Katsunori; Takeuchi, Daichi; Ikeda, Mitsuhisa; Ohta, Akio; Miyazaki, Seiichi

    2017-06-01

    Hydrogenated microcrystalline (µc) Si/Ge heterostructures were prepared on quartz substrates by plasma-enhanced chemical vapor deposition (CVD) from VHF inductively coupled plasma of SiH4 just after GeH4 employing Ni nanodots (NDs) as seeds for crystalline nucleation. The crystallinity of the films and the progress of grain growth were characterized by Raman scattering spectroscopy and atomic force microscopy (AFM), respectively. When the Ge films were grown on Ni-NDs at 250 °C, the growth of µc-Ge films with crystallinity as high as 80% was realized without an amorphous phase near the Ge film/quartz substrate interface. After the subsequent Si film deposition at 250 °C, fine grains were formed in the early stages of film growth on µc-Ge films with compositional mixing (µc-Si0.85Ge0.15:H) caused by the release of large lattice mismatch between c-Si and c-Ge. With further increase in Si:H film thickness, the formation of large grain structures accompanied by fine grains was promoted. These results suggest that crystalline Si/Ge heterojunctions can be used for efficient carrier collection in solar cell application.

  4. Internal modes in high-temperature plasmas

    International Nuclear Information System (INIS)

    Crew, G.B.

    1983-02-01

    The linear stability of current-carrying toroidal plamsas is examined to determine the possibility of exciting global internal modes. The ideal magnetohydrodynamic (MHD) theory provides a useful framework for the analysis of these modes, which involve a kinking of the central portion of the plasma column. Non-ideal effects can also be important, and these are treated for high-temperature regimes where the plasma is collisionless

  5. 2-D Temperature Mapping in Fluorocarbon Plasmas

    Science.gov (United States)

    Steffens, Kristen L.; Sobolewski, Mark A.

    2005-09-01

    Two-dimensional maps of rotational temperature in CF4 plasmas were determined using planar laser-induced fluorescence measurements of CF A2Σ+ - X2Π (1,0). Rotational temperatures are expected to be in equilibrium with gas temperatures under the present conditions. Experiments were performed in a capacitively-coupled, parallel-plate reactor at pressures from 27 Pa to 107 Pa and powers of 10 W to 30 W. The effects of electrode cooling and having a wafer present were also examined. Measured temperatures ranged between 273 K±15 K and 480 K±15 K. The strong temperature gradients found in these plasmas can have serious effects on density measurements that probe a single rotational level, as well as on reaction rate constants and interpretation of density gradients.

  6. Effect of the substrate surface topology and temperature on the structural properties of ZnO layers obtained by plasma enhanced chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Kitova, S; Danev, G, E-mail: skitova@clf.bas.b [Acad. J .Malinowski Central Laboratory of Photoprocesses, Bulgarian Academy of Sciences, Acad. G. Bonchev Str., Bl.109, 1113 Sofia (Bulgaria)

    2010-04-01

    In this work thin ZnO layers were grown by metal-organic PECVD (RF 13.56 MHz) on Si wafers. Zn acetylacetonate was used as a precursor and oxygen as oxidant. A system for dosed injection of the precursor and oxidant into the plasma reactor was developed. The influence of the substrate surface topology and temperature on the structural properties of the deposited layers was studied. ZnO and graphite powder dispersions were used to modify the silicon wafers before starting the deposition process of the layers. Some of the ZnO layers were deposited on the back, unpolished, side of Si wafers. Depositions at 400 {sup 0}C were performed to examine the effect of the substrate temperatures on the layer growth. The film structure was examined by XRD and SEM. The results show that all layers are crystalline with hexagonal wurtzite structure. The crystallites are preferentially oriented along the c-axis direction perpendicular to the substrate surfaces. ZnO layers deposited on thin ZnO seed films and clean Si surface exhibit well-developed grain structures and more c-axis preferred phase with better crystal quality than that of the layers deposited on graphite seed layer or rough, unpolished Si wafer.

  7. Active neutral particle diagnostics for high temperature plasma

    International Nuclear Information System (INIS)

    Tobita, Kenji

    1993-01-01

    This paper describes experimental studies related to active neutral particle diagnostics in the JT-60 tokamak. Detection efficiencies of a micro-channel plate (MCP), which has widely used in plasma diagnostics, were determined for ions and neutrals. Multi-step processes for a neutral beam is predicted to enhance the beam stopping cross section in a plasma. In order to confirm the predictions, shine-through for a hydrogen and for a helium beam was measured in the JT-60 ohmic plasmas. The measurements for a hydrogen beam resulted in the cross sectional enhancement in the beam stopping. The same experiment using a helium beam indicated that the cross sectional enhancement for helium was much smaller than that for hydrogen at almost same plasma parameters. Ion temperature diagnostic using active beam scattering was developed in data processing technique, in consideration of the device function of a neutral particle analyzer and in estimation of the effect of beam ion component. Fundamental experiments for detecting helium ions in a plasma were performed using two-electron transfer reaction between a helium atomic beam and helium ions, and the energy distribution and the density of the helium ions were determined. These experiments demonstrated promise of the two-electron transfer reaction as an alpha ash detection in a burning plasma. A parasitic neutral efflux accompanied by active beam injection was investigated. (J.P.N.)

  8. Spectroscopic diagnostics of high temperature plasmas

    International Nuclear Information System (INIS)

    Moos, W.

    1990-01-01

    A three-year research program for the development of novel XUV spectroscopic diagnostics for magnetically confined fusion plasmas is proposed. The new diagnostic system will use layered synthetic microstructures (LSM) coated, flat and curved surfaces as dispersive elements in spectrometers and narrow band XUV filter arrays. In the framework of the proposed program we will develop impurity monitors for poloidal and toroidal resolved measurements on PBX-M and Alcator C-Mod, imaging XUV spectrometers for electron density and temperature fluctuation measurements in the hot plasma core in TEXT or other similar tokamaks and plasma imaging devices in soft x-ray light for impurity behavior studies during RF heating on Phaedrus T and carbon pellet ablation in Alcator C-Mod. Recent results related to use of multilayer in XUV plasma spectroscopy are presented. We also discuss the latest results reviewed to q o and local poloidal field measurements using Zeeman polarimetry

  9. Theory of high temperature plasmas. Final report

    International Nuclear Information System (INIS)

    Davidson, R.C.; Liu, C.S.

    1977-01-01

    This is a report on the technical progress in our analytic studies of high-temperature fusion plasmas. We also emphasize that the research summarized here makes extensive use of computational methods and therefore forms a strong interface with our numerical modeling program which is discussed later in the report

  10. The concept of temperature in space plasmas

    Science.gov (United States)

    Livadiotis, G.

    2017-12-01

    Independently of the initial distribution function, once the system is thermalized, its particles are stabilized into a specific distribution function parametrized by a temperature. Classical particle systems in thermal equilibrium have their phase-space distribution stabilized into a Maxwell-Boltzmann function. In contrast, space plasmas are particle systems frequently described by stationary states out of thermal equilibrium, namely, their distribution is stabilized into a function that is typically described by kappa distributions. The temperature is well-defined for systems at thermal equilibrium or stationary states described by kappa distributions. This is based on the equivalence of the two fundamental definitions of temperature, that is (i) the kinetic definition of Maxwell (1866) and (ii) the thermodynamic definition of Clausius (1862). This equivalence holds either for Maxwellians or kappa distributions, leading also to the equipartition theorem. The temperature and kappa index (together with density) are globally independent parameters characterizing the kappa distribution. While there is no equation of state or any universal relation connecting these parameters, various local relations may exist along the streamlines of space plasmas. Observations revealed several types of such local relations among plasma thermal parameters.

  11. Temperature effect on protection diode for plasma-process induced charging damage

    NARCIS (Netherlands)

    Wang, Zhichun; Scarpa, A.; Smits, Sander M.; Kuper, F.G.; Salm, Cora

    2002-01-01

    In this paper, the leakage current of different drain-well diodes for plasma-charging protection has been simulated at high temperature. The simulation shows that the high ambient temperature, especially during plasma deposition process, enormously enhances the efficacy of the protection diodes in

  12. Anomalous plasma transport due to electron temperature gradient instability

    International Nuclear Information System (INIS)

    Tokuda, Sinji; Ito, Hiroshi; Kamimura, Tetsuo.

    1979-01-01

    The collisionless drift wave instability driven by an electron temperature inhomogeneity (electron temperature gradient instability) and the enhanced transport processes associated with it are studied using a two-and-a-half dimensional particle simulation code. The simulation results show that quasilinear diffusion in phase space is an important mechanism for the saturation of the electron temperature gradient instability. Also, the instability yields particle fluxes toward the hot plasma regions. The heat conductivity of the electron temperature perpendicular to the magnetic field, T sub(e'), is not reduced by magnetic shear but remains high, whereas the heat conductivity of the parallel temperature, T sub(e''), is effectively reduced, and the instability stabilized. (author)

  13. Enhancement of EAST plasma control capabilities

    Energy Technology Data Exchange (ETDEWEB)

    Xiao, Bingjia, E-mail: bjxiao@ipp.ac.cn [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China); School of Nuclear Science and Technology, University of Science and Technology of China, Hefei (China); Yuan, Qiping; Luo, Zhengping; Huang, Yao; Liu, Lei; Guo, Yong; Pei, Xiaofang; Chen, Shuliang [Institute of Plasma Physics, Chinese Academy of Sciences, Hefei (China); Humphreys, D.A.; Hyatt, A.W. [General Atomics, P.O. Box 85608, San Diego, CA 92186-5608 (United States); Mueller, Dennis [Princeton Plasma Physics Laboratory, Princeton, NJ (United States); Calabró, G.; Crisanti, F. [ENEA UnitàTecnicaFusione, C.R. Frascati, Via E. Fermi 45, 00044 Frascati, Roma (Italy); Albanese, R.; Ambrosino, R. [CREATE, Università di Napoli Federicao II, Università di Cassino and Università di Napoli Parthenope, Via Claudio 19, 80125 Napoli (Italy)

    2016-11-15

    Highlights: • Parallel plasma equilibrium reconstruction using GPU for real-time control on EAST. • Vertical control using Bang-bang + PID method to improve the response and minimize the oscillation caused by the latency. • Quasi-snow flake divertor plasma configuration has been demonstrated on EAST. - Abstract: In order to improve the plasma control performance and enhance the capability for advanced plasma control, new algorithms such as PEFIT/ISOFLUX plasma shape feedback control, quasi-snowflake plasma shape development and vertical control under new vertical control power supply, have been implemented and experimentally tested and verified in EAST 2014 campaign. P-EFIT is a rewritten version of EFIT aiming at fast real-time equilibrium reconstruction by using GPU for parallelized computation. Successful control using PEFIT/ISOFLUX was established in dedicated experiment. Snowfldivertor plasma shape has the advantage of spreading heat over the divertor target and a quasi-snowflake (QSF) configuration was achieved in discharges with I{sub p} = 0.25 MA and B{sub t} = 1.8T, κ∼1.9, by plasma position feedback control. The shape feedback control to achieve QSF shape has been preliminary implemented by using PEFIT and the initial experimental test has been done. For more robust vertical instability control, the inner coil (IC) and its power supply have been upgraded. A new control algorithm with the combination of Bang-bang and PID controllers has been developed. It is shown that new vertical control power supply together with the new control algorithms results in higher vertical controllability.

  14. Temperature measurements in thermonuclear plasmas; Mesures des temperatures dans les plasmas thermonucleaires

    Energy Technology Data Exchange (ETDEWEB)

    Breton, D [Commissariat a l' Energie Atomique, Saclay (France). Centre d' Etudes Nucleaires

    1958-07-01

    The temperatures needed to produce thermonuclear reactions are of the order of several million degrees Kelvin. Devising methods for measuring such temperatures has been the subject of research in many countries. In order to present the problem clearly and to demonstrate its importance, the author reviews the various conditions which must be fulfilled in order that reactions may be qualified as thermonuclear. The relationship between the temperature and the cross-section of the reactions is studied, and it is shown that the notion of temperature in the plasmas is complex, which leads to a consideration of the temperature of the ions and that of the electrons. None of the methods for the temperature measurements is completely satisfactory because of the hypotheses which must be made, and which are seldom fulfilled during high-intensity discharges in the plasmas. In practice it is necessary to use several methods simultaneously. (author) [French] Les temperatures necessaires pour produire des reactions thermonucleaires sont de l'ordre de plusieurs millions de degres Kelvin. Les methodes envisagees pour mesurer ces temperatures font l'objet de recherches dans de nombreux pays. Afin de preciser le probleme et de montrer son importance, l'auteur rappelle les conditions qui doivent etre reunies pour que des reactions puissent etre qualifiees thermonucleaires. Il etudie la relation entre la temperature et la section efficace des reactions et montre que la notion de temperature dans les plasmas est complexe, ce qui amene a considerer la temperature des ions et celle des electrons. Aucune des methodes de mesure des temperatures n'est completement satisfaisante en raison des hypotheses qu'elles exigent et qui sont rarement realisees lors des decharges a haute intensite dans les plasmas. En pratique, il est necessaire d'utiliser plusieurs methodes simultanement. (auteur)

  15. Low temperature plasma biomedicine: A tutorial review

    International Nuclear Information System (INIS)

    Graves, David B.

    2014-01-01

    Gas discharge plasmas formed at atmospheric pressure and near room temperature have recently been shown to be potentially useful for surface and wound sterilization, antisepsis, bleeding cessation, wound healing, and cancer treatment, among other biomedical applications. This tutorial review summarizes the field, stressing the likely role of reactive oxygen and nitrogen species created in these plasmas as the biologically and therapeutically active agents. Reactive species, including radicals and non-radical compounds, are generated naturally within the body and are now understood to be essential for normal biological functions. These species are known to be active agents in existing therapies for wound healing, infection control, and cancer treatment. But they are also observed at elevated levels in persons with many diseases and are associated with aging. The physical and chemical complexity of plasma medical devices and their associated biochemical effects makes the development of safe, effective plasma medical devices and procedures a challenge, but encouragingly rapid progress has been reported around the world in the last several years

  16. Low temperature plasma biomedicine: A tutorial review

    Energy Technology Data Exchange (ETDEWEB)

    Graves, David B., E-mail: graves@berkeley.edu [University of California at Berkeley, Berkeley, California 94720 (United States)

    2014-08-15

    Gas discharge plasmas formed at atmospheric pressure and near room temperature have recently been shown to be potentially useful for surface and wound sterilization, antisepsis, bleeding cessation, wound healing, and cancer treatment, among other biomedical applications. This tutorial review summarizes the field, stressing the likely role of reactive oxygen and nitrogen species created in these plasmas as the biologically and therapeutically active agents. Reactive species, including radicals and non-radical compounds, are generated naturally within the body and are now understood to be essential for normal biological functions. These species are known to be active agents in existing therapies for wound healing, infection control, and cancer treatment. But they are also observed at elevated levels in persons with many diseases and are associated with aging. The physical and chemical complexity of plasma medical devices and their associated biochemical effects makes the development of safe, effective plasma medical devices and procedures a challenge, but encouragingly rapid progress has been reported around the world in the last several years.

  17. Low temperature plasma biomedicine: A tutorial reviewa)

    Science.gov (United States)

    Graves, David B.

    2014-08-01

    Gas discharge plasmas formed at atmospheric pressure and near room temperature have recently been shown to be potentially useful for surface and wound sterilization, antisepsis, bleeding cessation, wound healing, and cancer treatment, among other biomedical applications. This tutorial review summarizes the field, stressing the likely role of reactive oxygen and nitrogen species created in these plasmas as the biologically and therapeutically active agents. Reactive species, including radicals and non-radical compounds, are generated naturally within the body and are now understood to be essential for normal biological functions. These species are known to be active agents in existing therapies for wound healing, infection control, and cancer treatment. But they are also observed at elevated levels in persons with many diseases and are associated with aging. The physical and chemical complexity of plasma medical devices and their associated biochemical effects makes the development of safe, effective plasma medical devices and procedures a challenge, but encouragingly rapid progress has been reported around the world in the last several years.

  18. Temperature relaxation in collisional non equilibrium plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Potapenko, I.F.; Bobylev, A.V.; Azevedo, C.A.; Assis, A.S. [Universidade do Estado, Rio de Janeiro, RJ (Brazil). Inst. de Fisica

    1997-12-31

    Full text. We study the relaxation of a space uniform plasma composed of electrons and one species of ions. To simplified the consideration, standard approach is usually accepted: the distribution functions are considered to be a Maxwellian with time dependent electron T{sub e}(t) and ion T{sub i}(t) temperatures. This approach imposes a severe restriction on the electron/ion distributions that could be very far from the equilibrium. In the present work the problem is investigated on the basis of the nonlinear kinetic Fokker - Planck equation, which is widely used for the description of collisional plasmas. This equation has many applications in plasma physics as an intrinsic part of physical models, both analytical and numerical. A new detailed description of this classical problem of the collisional plasma kinetic theory is given. A deeper examination of the problem shows that the unusual perturbation theory can not be used. The part of the perturbation of the electron distribution has the character of a boundary layer in the neighborhood of small velocities. In this work the boundary layer is thoroughly studied. The correct distribution electron function is given. Nonmonotonic character of the distribution relaxation in the tail region is observed. The corrected formula for temperature equalization is obtained. The comparison of the calculation results with the asymptotic approach is made. We should stress the important role of the completely conservative different scheme used here, which keeps the symmetric properties of the nonlinear exact equation. This allows us to make calculations without numerical error accumulations, except for machine errors. (author)

  19. Toroidal plasma enhanced CVD of diamond films

    International Nuclear Information System (INIS)

    Zvanya, John; Cullen, Christopher; Morris, Thomas; Krchnavek, Robert R.; Holber, William; Basnett, Andrew; Basnett, Robert; Hettinger, Jeffrey

    2014-01-01

    An inductively coupled toroidal plasma source is used as an alternative to microwave plasmas for chemical vapor deposition of diamond films. The source, operating at a frequency of 400 kHz, synthesizes diamond films from a mixture of argon, methane, and hydrogen. The toroidal design has been adapted to create a highly efficient environment for diamond film deposition: high gas temperature and a short distance from the sample to the plasma core. Using a toroidal plasma geometry operating in the medium frequency band allows for efficient (≈90%) coupling of AC line power to the plasma and a scalable path to high-power and large-area operation. In test runs, the source generates a high flux of atomic hydrogen over a large area, which is favorable for diamond film growth. Using a deposition temperature of 900–1050 °C and a source to sample distance of 0.1–2.0 cm, diamond films are deposited onto silicon substrates. The results showed that the deposition rate of the diamond films could be controlled using the sample temperature and source to sample spacing. The results also show the films exhibit good-quality polycrystalline diamond as verified by Raman spectroscopy, x-ray diffraction, and scanning electron microscopy. The scanning electron microscopy and x-ray diffraction results show that the samples exhibit diamond (111) and diamond (022) crystallites. The Raman results show that the sp 3 peak has a narrow spectral width (FWHM 12 ± 0.5 cm −1 ) and that negligible amounts of the sp 2 band are present, indicating good-quality diamond films

  20. Multichannel euv spectroscopy of high temperature plasmas

    International Nuclear Information System (INIS)

    Fonck, R.J.

    1983-11-01

    Spectroscopy of magnetically confined high temperature plasmas in the visible through x-ray spectral ranges deals primarily with the study of impurity line radiation or continuum radiation. Detailed knowledge of absolute intensities, temporal behavior, and spatial distributions of the emitted radiation is desired. As tokamak facilities become more complex, larger, and less accessible, there has been an increased emphasis on developing new instrumentation to provide such information in a minimum number of discharges. The availability of spatially-imaging detectors for use in the vacuum ultraviolet region (especially the intensified photodiode array) has generated the development of a variety of multichannel spectrometers for applications on tokamak facilities

  1. Remote plasma-enhanced metalorganic chemical vapor deposition of aluminum oxide thin films

    NARCIS (Netherlands)

    Volintiru, I.; Creatore, M.; Hemmen, van J.L.; Sanden, van de M.C.M.

    2008-01-01

    Aluminum oxide films were deposited using remote plasma-enhanced metalorganic chemical vapor deposition from oxygen/trimethylaluminum mixtures. Initial studies by in situ spectroscopic ellipsometry demonstrated that the aluminum oxide films deposited at temperatures

  2. Atomic processes in high temperature plasmas

    International Nuclear Information System (INIS)

    Hahn, Y.

    1991-07-01

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

  3. Spectroscopic analysis applied to temperature measurement in plasmas

    International Nuclear Information System (INIS)

    Fieffe-Prevost, P.

    1978-01-01

    The plasma temperature is defined only if the plasma is in a state near thermodynamic equilibrium. This plasma state is analysed in detail and spectroscopic methods for measuring the temperature are discussed. As an application the hydrogen arc of the National Institute of Metrology of the Conservatoire National des Arts et Metiers (Paris) is briefly described [fr

  4. Measurement of temperature, electric conductivity and density of plasma

    International Nuclear Information System (INIS)

    Vasilevova, I.; Nefedov, A.; Oberman, F.; Urinson, A.

    1982-01-01

    Three instruments are briefly described developed by the High Temperatures Institute of the USSR Academy of Sciences for the measurement of plasma temperature, electric conductivity and density. The temperature measuring instrument uses as a standard a light source whose temperature may significantly differ from plasma temperature because three light fluxes are compared, namely the flux emitted by the plasma, the flux emitted directly by the standard source, and the flux emitted by the standard source after passage through the plasma. The results of measurement are computer processed. Electric conductivity is measured using a coil placed in a probe which is automatically extended for a time of maximally 0.3 seconds into the plasma stream. The equipment for measuring plasma density consists of a special single-channel monochromator, a temperature gauge, a plasma pressure gauge, and of a computer for processing the results of measurement. (Ha)

  5. Measurement of the argon plasma temperature by use of pyrometer

    International Nuclear Information System (INIS)

    Wang Fanhou; Jing Fuqian

    2002-01-01

    The author describes in detail how to use pyrometer to measure the plasma temperature. The temperatures of shock-generated argon plasmas are given in the present work. Measured results of temperature-pressure curve are compared with calculated results using Saha-Debye-Huckel model, which are in good agreement

  6. Tungsten Deposition on Graphite using Plasma Enhanced Chemical Vapour Deposition

    International Nuclear Information System (INIS)

    Sharma, Uttam; Chauhan, Sachin S; Sharma, Jayshree; Sanyasi, A K; Ghosh, J; Choudhary, K K; Ghosh, S K

    2016-01-01

    The tokamak concept is the frontrunner for achieving controlled thermonuclear reaction on earth, an environment friendly way to solve future energy crisis. Although much progress has been made in controlling the heated fusion plasmas (temperature ∼ 150 million degrees) in tokamaks, technological issues related to plasma wall interaction topic still need focused attention. In future, reactor grade tokamak operational scenarios, the reactor wall and target plates are expected to experience a heat load of 10 MW/m 2 and even more during the unfortunate events of ELM's and disruptions. Tungsten remains a suitable choice for the wall and target plates. It can withstand high temperatures, its ductile to brittle temperature is fairly low and it has low sputtering yield and low fuel retention capabilities. However, it is difficult to machine tungsten and hence usages of tungsten coated surfaces are mostly desirable. To produce tungsten coated graphite tiles for the above-mentioned purpose, a coating reactor has been designed, developed and made operational at the SVITS, Indore. Tungsten coating on graphite has been attempted and successfully carried out by using radio frequency induced plasma enhanced chemical vapour deposition (rf -PECVD) for the first time in India. Tungsten hexa-fluoride has been used as a pre-cursor gas. Energy Dispersive X-ray spectroscopy (EDS) clearly showed the presence of tungsten coating on the graphite samples. This paper presents the details of successful operation and achievement of tungsten coating in the reactor at SVITS. (paper)

  7. Plasma enhanced atomic layer deposited MoOx emitters for silicon heterojunction solar cells

    OpenAIRE

    Ziegler, J.; Mews, M.; Kaufmann, K.; Schneider, T.; Sprafke, A.N.; Korte, L.; Wehrsporn, R.B

    2015-01-01

    A method for the deposition of molybdenum oxide MoOx with high growth rates at temperatures below 200 C based on plasma enhanced atomic layer deposition is presented. The stoichiometry of the overstoichiometric MoOx films can be adjusted by the plasma parameters. First results of these layers acting as hole selective contacts in silicon heterojunction solar cells are presented and discussed

  8. Low temperature plasma-enhanced ALD TiN ultrathin films for Hf{sub 0.5}Zr{sub 0.5}O{sub 2}-based ferroelectric MIM structures

    Energy Technology Data Exchange (ETDEWEB)

    Kozodaev, M.G.; Chernikova, A.G.; Markeev, A.M. [Moscow Institute of Physics and Technology, Institutsky Lane 9, Dolgoprudny, Moscow Region 141700 (Russian Federation); Lebedinskii, Y.Y. [Moscow Institute of Physics and Technology, Institutsky Lane 9, Dolgoprudny, Moscow Region 141700 (Russian Federation); National Research Nuclear University MEPhI, Moscow Engineering Physics Institute, Kashirskoye Shosse 31, 115409 Moscow (Russian Federation); Polyakov, S.N. [Technological Institute for Superhard and Novel Carbon Materials, Tsentral' naya str. 7a, 142190, Troitsk, Moscow (Russian Federation)

    2017-06-15

    In this work chemical and electrical properties of TiN films, grown by low temperature plasma-enhanced atomic layer deposition (PE-ALD) process from TiCl{sub 4} and NH{sub 3}, were investigated. Electrical resistivity as low as 250 μOhm x cm, as well as the lowest Cl impurity content, was achieved at 320 C. Full-ALD Hf{sub 0.5}Zr{sub 0.5}O{sub 2}-based metal-ferroelectric-metal capacitor with TiN electrodes was fabricated and its electrical properties were investigated. It was also shown that the proposed PE-ALD process provides an early film continuity, which was confirmed by ultrathin fully continuous film growth. Such ultrathin (3 nm) and fully continuous TiN film was also successfully implemented as the top electrode to Hf{sub 0.5}Zr{sub 0.5}O{sub 2}-based ferroelectric capacitor. Angle-resolved X-ray photoelectron spectroscopy (AR-XPS) was used for its thickness determination and a visible wake-up effect in underlying Hf{sub 0.5}Zr{sub 0.5}O{sub 2} layer was clearly observed. (copyright 2017 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  9. Modelling of a multi-temperature plasma composition

    International Nuclear Information System (INIS)

    Liani, B.; Benallal, R.; Bentalha, Z.

    2005-01-01

    Knowledge of plasma composition is very important for various plasma applications and prediction of plasma properties. The authors use the Saha equation and Debye length equation to calculate the non-local thermodynamic-equilibrium plasma composition. It has been shown that the model to 2T with T representing the temperature (electron temperature and heavy-particle temperature) described by Chen and Han [J. Phys. D 32(1999)1711] can be applied for a mixture of gases, where each atomic species has its own temperature, but the model to 4T is more general because it can be applicable to temperatures distant enough of the heavy particles. This can occur in a plasma composed of big- or macro-molecules. The electron temperature T e varies in the range 8000∼20000 K at atmospheric pressure. (authors)

  10. Frugal Biotech Applications of Low-Temperature Plasma.

    Science.gov (United States)

    Machala, Zdenko; Graves, David B

    2017-09-01

    Gas discharge low-temperature air plasma can be utilized for a variety of applications, including biomedical, at low cost. We term these applications 'frugal plasma' - an example of frugal innovation. We demonstrate how simple, robust, low-cost frugal plasma devices can be used to safely disinfect instruments, surfaces, and water. Copyright © 2017 Elsevier Ltd. All rights reserved.

  11. Generators of nonequilibrium low-temperature plasma

    International Nuclear Information System (INIS)

    Dautov, G.Yu.

    1988-01-01

    Results are described of a study and of the characteristics of sources of a non-equilibrium gas-discharge plasma. The plasma generators considered include glow, high frequency, and arc discharge generators. Thermodynamic, ionic, and electronic processes occurring in the plasmas are evaluated

  12. Criteria governing electron plasma waves in a two-temperature plasma

    International Nuclear Information System (INIS)

    Dell, M.P.; Gledhill, I.M.A.; Hellberg, M.A.

    1987-01-01

    Using a technique based on the saddle-points of the dielectric function, criteria are found which govern the behaviour of electron plasma waves in plasmas with two electron populations having different temperatures. (orig.)

  13. Interaction of heavy ion beams with a hydrogen plasma: plasma lens effect and stopping power enhancement

    International Nuclear Information System (INIS)

    Gardes, D.; Bimbot, R.; Della-Negra, S.; Dumail, M.; Kubica, B.; Richard, A.; Rivet, M.F.; Servajean, A.; Deutsch, C.; Maynard, G.

    1988-01-01

    By coupling a hydrogen plasma to a Tandem accelerator, transmission and energy losses of 2 MeV/u carbon and sulfur beams passing through a plasma target have been investigated. Fluctuations in beam transmission have been observed and attributed to a plasma lens effect. Moreover, energy loss measurements indicate an enhanced stopping power of the plasma relative to its cold matter equivalent

  14. Temperature measurement in low pressure plasmas. Temperaturmessungen im Niederdruckplasma

    Energy Technology Data Exchange (ETDEWEB)

    Rosenbauer, K.A.; Wilting, H.; Schramm, G. (Duesseldorf Univ. (Germany, F.R.). Abt. fuer Histologie und Embryologie)

    1989-11-01

    The present work discusses the influence of various parameters on the substrate temperature in a low pressure plasma. The measurement method chosen utilized Signotherm (Merck) temperature sensors embedded in silicon between two glass substrates. All measurements were made in a 200 G Plasma Processor from Technics Plasma GmbH. The substrate temperature is dependent on the process time, the RF power, the process gas and the position in the chamber. The substrate temperature increases with increasing process time and increasing power. Due to the location of the microwave port from the magnetron to the chamber, the substrate temperature is highest in the center of the chamber. Measurements performed in an air plasma yielded higher results than in an oxygen plasma. (orig.).

  15. Foundations of low-temperature plasma physics—an introduction

    Science.gov (United States)

    von Keudell, A.; Schulz-von der Gathen, V.

    2017-11-01

    The use of plasmas as a reactive mixture of ions, electrons and neutrals is at the core of numerous technologies in industry, enabling applications in microelectronics, automotives, packaging, environment and medicine. Recently, even the use of plasmas in medical applications has made great progress. The dominant character of a plasma is often its non equilibrium nature with different temperatures for the individual species in a plasma, the ions, electrons and neutrals. This opens up a multitude of reaction pathways which are inaccessible to conventional methods in chemistry, for example. The understanding of plasmas requires expertise in plasma physics, plasma chemistry and in electrical engineering. This first paper in a series of foundation papers on low temperature plasma science is intended to provide the very basics of plasmas as a common starting point for the more in-depth discussion of particular plasma generation methods, plasma modeling and diagnostics in the other foundation papers. In this first paper of the series, the common terminology, definitions and main concepts are introduced. The covered aspects start with the basic definitions and include further plasma equilibria, particle collisions and transport, sheaths and discharge breakdowns.

  16. Industrial applications of low-temperature plasma physics

    International Nuclear Information System (INIS)

    Chen, F.F.

    1995-01-01

    The application of plasma physics to the manufacturing and processing of materials may be the new frontier of our discipline. Already partially ionized discharges are used in industry, and the performance of plasmas has a large commercial and technological impact. However, the science of low-temperature plasmas is not as well developed as that of high-temperature, collisionless plasmas. In this paper several major areas of application are described and examples of forefront problems in each are given. The underlying thesis is that gas discharges have evolved beyond a black art, and that intellectually challenging problems with elegant solutions can be found. copyright 1995 American Institute of Physics

  17. Role of plasma enhanced atomic layer deposition reactor wall conditions on radical and ion substrate fluxes

    Energy Technology Data Exchange (ETDEWEB)

    Sowa, Mark J., E-mail: msowa@ultratech.com [Ultratech/Cambridge NanoTech, 130 Turner Street, Building 2, Waltham, Massachusetts 02453 (United States)

    2014-01-15

    Chamber wall conditions, such as wall temperature and film deposits, have long been known to influence plasma source performance on thin film processing equipment. Plasma physical characteristics depend on conductive/insulating properties of chamber walls. Radical fluxes depend on plasma characteristics as well as wall recombination rates, which can be wall material and temperature dependent. Variations in substrate delivery of plasma generated species (radicals, ions, etc.) impact the resulting etch or deposition process resulting in process drift. Plasma enhanced atomic layer deposition is known to depend strongly on substrate radical flux, but film properties can be influenced by other plasma generated phenomena, such as ion bombardment. In this paper, the chamber wall conditions on a plasma enhanced atomic layer deposition process are investigated. The downstream oxygen radical and ion fluxes from an inductively coupled plasma source are indirectly monitored in temperature controlled (25–190 °C) stainless steel and quartz reactors over a range of oxygen flow rates. Etch rates of a photoresist coated quartz crystal microbalance are used to study the oxygen radical flux dependence on reactor characteristics. Plasma density estimates from Langmuir probe ion saturation current measurements are used to study the ion flux dependence on reactor characteristics. Reactor temperature was not found to impact radical and ion fluxes substantially. Radical and ion fluxes were higher for quartz walls compared to stainless steel walls over all oxygen flow rates considered. The radical flux to ion flux ratio is likely to be a critical parameter for the deposition of consistent film properties. Reactor wall material, gas flow rate/pressure, and distance from the plasma source all impact the radical to ion flux ratio. These results indicate maintaining chamber wall conditions will be important for delivering consistent results from plasma enhanced atomic layer deposition

  18. Branched carbon nanofiber network synthesis at room temperature using radio frequency supported microwave plasmas

    OpenAIRE

    Boskovic, BO; Stolojan, V; Zeze, DA; Forrest, RD; Silva, SRP; Haq, S

    2004-01-01

    Carbon nanofibers have been grown at room temperature using a combination of radio frequency and microwave assisted plasma-enhanced chemical vapor deposition. The nanofibers were grown, using Ni powder catalyst, onto substrates kept at room temperature by using a purposely designed water-cooled sample holder. Branched carbon nanofiber growth was obtained without using a template resulting in interconnected carbon nanofiber network formation on substrates held at room temperatur...

  19. Low temperature plasma metallurgy. Reduction of metals in plasma reactors

    Czech Academy of Sciences Publication Activity Database

    Eliáš, M.; Frgala, Z.; Kudrle, V.; Janča, J.; Brožek, Vlastimil

    2004-01-01

    Roč. 7, č. 1 (2004), s. 91-97 ISSN 1203-8407 Institutional research plan: CEZ:AV0Z2043910 Keywords : plasmachemistry reduction, tungsten, hydrogen plasma Subject RIV: JH - Ceramics, Fire-Resistant Materials and Glass Impact factor: 0.451, year: 2002

  20. Low Temperature Atmospheric Pressure Plasma Sterilization Shower

    Data.gov (United States)

    National Aeronautics and Space Administration — The goal is to develop an atmospheric plasma jet that is capable of depositing a wide variety of materials on flexible substrates such as paper, plastic, cotton and...

  1. The physics of the low-temperature plasma in Czechoslovakia

    International Nuclear Information System (INIS)

    Kracik, J.

    1985-01-01

    A survey is given of low-temperature plasma research in Czechoslovakia since 1954 and its main results are pointed out. In the first years, various processes in electric discharges and electromagnetic acceleration of plasma clusters were studied at Czechoslovak universities and in the Institute of Physics. In the study of ionization waves, Czechoslovak physicists achieved world priority. Later on, low-temperature plasma investigation began in the Institute of Plasma Physics, founded in 1959. The issues of plasma interaction with the solid state and plasma applications in plasma chemistry were studied mainly by its Department of Applied Plasma Physics. The main effort of this group, transferred recently to the Institute of Physics, is aimed at thin film production and plasma-surface interactions; similar experimental studies are also carried out at universities in Brno and Bratislava. Last but not least, arc spraying of powder materials using water-cooled plasmatrons is being developed by the Department of Plasma Technology of the Institute of Plasma Physics. (J.U.)

  2. Microwave plasma-assisted photoluminescence enhancement in nitrogen-doped ultrananocrystalline diamond film

    Directory of Open Access Journals (Sweden)

    Yu Lin Liu

    2012-06-01

    Full Text Available Optical properties and conductivity of nitrogen-doped ultrananocrystal diamond (UNCD films were investigated following treatment with low energy microwave plasma at room temperature. The plasma also generated vacancies in UNCD films and provided heat for mobilizing the vacancies to combine with the impurities, which formed the nitrogen-vacancy defect centers. The generated color centers were distributed uniformly in the samples. The conductivity of nitrogen-doped UNCD films treated by microwave plasma was found to decrease slightly due to the reduced grain boundaries. The photoluminescence emitted by the plasma treated nitrogen-doped UNCD films was enhanced significantly compared to the untreated films.

  3. Spectroscopic determination of temperatures in plasmas generated by arc torches

    Czech Academy of Sciences Publication Activity Database

    Mašláni, Alan; Sember, Viktor; Hrabovský, Milan

    2017-01-01

    Roč. 133, July (2017), s. 14-20 ISSN 0584-8547 R&D Projects: GA ČR(CZ) GA15-19444S Institutional support: RVO:61389021 Keywords : Arc plasma torch * Optical emission spectroscopy * Temperature * Boltzmann plot Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 3.241, year: 2016

  4. Temperature of thermal plasma jets: A time resolved approach

    Energy Technology Data Exchange (ETDEWEB)

    Sahasrabudhe, S N; Joshi, N K; Barve, D N; Ghorui, S; Tiwari, N; Das, A K, E-mail: sns@barc.gov.i [Laser and Plasma Technology Division, Bhabha Atomic Research Centre, Mumbai - 400 094 (India)

    2010-02-01

    Boltzmann Plot method is routinely used for temperature measurement of thermal plasma jets emanating from plasma torches. Here, it is implicitly assumed that the plasma jet is 'steady' in time. However, most of the experimenters do not take into account the variations due to ripple in the high current DC power supplies used to run plasma torches. If a 3-phase transductor type of power supply is used, then the ripple frequency is 150 Hz and if 3- phase SCR based power supply is used, then the ripple frequency is 300 Hz. The electrical power fed to plasma torch varies at ripple frequency. In time scale, it is about 3.3 to 6.7 ms for one cycle of ripple and it is much larger than the arc root movement times which are within 0.2 ms. Fast photography of plasma jets shows that the luminosity of plasma jet also varies exactly like the ripple in the power supply voltage and thus with the power. Intensity of line radiations varies nonlinearly with the instantaneous power fed to the torch and the simple time average of line intensities taken for calculation of temperature is not appropriate. In this paper, these variations and their effect on temperature determination are discussed and a method to get appropriate data is suggested. With a small adaptation discussed here, this method can be used to get temperature profile of plasma jet within a short time.

  5. Measurements of plasma temperature and electron density in laser

    Indian Academy of Sciences (India)

    The temperature and electron density characterizing the plasma are measured by time-resolved spectroscopy of neutral atom and ion line emissions in the time window of 300–2000 ns. An echelle spectrograph coupled with a gated intensified charge coupled detector is used to record the plasma emissions.

  6. Low-temperature plasma techniques in surface modification of biomaterials

    International Nuclear Information System (INIS)

    Feng Xiangfen; Xie Hankun; Zhang Jing

    2002-01-01

    Since synthetic polymers usually can not meet the biocompatibility and bio-functional demands of the human body, surface treatment is a prerequisite for them to be used as biomaterials. A very effective surface modification method, plasma treatment, is introduced. By immobilizing the bio-active molecules with low temperature plasma, polymer surfaces can be modified to fully satisfy the requirements of biomaterials

  7. Second topical conference on high-temperature plasma diagnostics

    International Nuclear Information System (INIS)

    Jahoda, F.C.; Freese, K.B.

    1978-02-01

    This report contains the program and abstracts of papers presented at the Second American Physical Society Topical Conference on High Temperature Plasma Diagnostics, March 1-3, 1978, Santa Fe, New Mexico

  8. Plasma characterization using terahertz-wave-enhanced fluorescence

    International Nuclear Information System (INIS)

    Liu Jingle; Zhang, X.-C.

    2010-01-01

    We demonstrate that the terahertz-wave-enhanced fluorescence emission from excited atoms or molecules can be employed in the characterization of laser-induced gas plasmas. The electron relaxation time and plasma density were deduced through applying the electron impact excitation/ionization and electron-ion recombination processes to the measured time-dependent enhanced fluorescence. The electron collision dynamics of nitrogen plasma excited at different gas pressures and laser pulse energies have been systematically investigated. This plasma characterization method provides picosecond temporal resolution and enables omnidirectional optical signal collection.

  9. A Computational Framework for Efficient Low Temperature Plasma Simulations

    Science.gov (United States)

    Verma, Abhishek Kumar; Venkattraman, Ayyaswamy

    2016-10-01

    Over the past years, scientific computing has emerged as an essential tool for the investigation and prediction of low temperature plasmas (LTP) applications which includes electronics, nanomaterial synthesis, metamaterials etc. To further explore the LTP behavior with greater fidelity, we present a computational toolbox developed to perform LTP simulations. This framework will allow us to enhance our understanding of multiscale plasma phenomenon using high performance computing tools mainly based on OpenFOAM FVM distribution. Although aimed at microplasma simulations, the modular framework is able to perform multiscale, multiphysics simulations of physical systems comprises of LTP. Some salient introductory features are capability to perform parallel, 3D simulations of LTP applications on unstructured meshes. Performance of the solver is tested based on numerical results assessing accuracy and efficiency of benchmarks for problems in microdischarge devices. Numerical simulation of microplasma reactor at atmospheric pressure with hemispherical dielectric coated electrodes will be discussed and hence, provide an overview of applicability and future scope of this framework.

  10. Improved Temperature Diagnostic for Non-Neutral Plasmas with Single-Electron Resolution

    Science.gov (United States)

    Shanman, Sabrina; Evans, Lenny; Fajans, Joel; Hunter, Eric; Nelson, Cheyenne; Sierra, Carlos; Wurtele, Jonathan

    2016-10-01

    Plasma temperature diagnostics in a Penning-Malmberg trap are essential for reliably obtaining cold, non-neutral plasmas. We have developed a setup for detecting the initial electrons that escape from a trapped pure electron plasma as the confining electrode potential is slowly reduced. The setup minimizes external noise by using a silicon photomultiplier to capture light emitted from an MCP-amplified phosphor screen. To take advantage of this enhanced resolution, we have developed a new plasma temperature diagnostic analysis procedure which takes discrete electron arrival times as input. We have run extensive simulations comparing this new discrete algorithm to our existing exponential fitting algorithm. These simulations are used to explore the behavior of these two temperature diagnostic procedures at low N and at high electronic noise. This work was supported by the DOE DE-FG02-06ER54904, and the NSF 1500538-PHY.

  11. Fly ash particles spheroidization using low temperature plasma energy

    OpenAIRE

    Shekhovtsov, V. V.; Volokitin, O. G.; Vitske, Rudolf Evaldovich; Kondratyuk, Alexey Alekseevich

    2016-01-01

    The paper presents the investigations on producing spherical particles 65-110 [mu]m in size using the energy of low temperature plasma (LTP). These particles are based on flow ash produced by the thermal power plant in Seversk, Tomsk region, Russia. The obtained spherical particles have no defects and are characterized by a smooth exterior surface. The test bench is designed to produce these particles. With due regard for plasma temperature field distribution, it is shown that the transition ...

  12. Effects of emitted electron temperature on the plasma sheath

    International Nuclear Information System (INIS)

    Sheehan, J. P.; Kaganovich, I. D.; Wang, H.; Raitses, Y.; Sydorenko, D.; Hershkowitz, N.

    2014-01-01

    It has long been known that electron emission from a surface significantly affects the sheath surrounding that surface. Typical fluid theory of a planar sheath with emitted electrons assumes that the plasma electrons follow the Boltzmann relation and the emitted electrons are emitted with zero energy and predicts a potential drop of 1.03T e /e across the sheath in the floating condition. By considering the modified velocity distribution function caused by plasma electrons lost to the wall and the half-Maxwellian distribution of the emitted electrons, it is shown that ratio of plasma electron temperature to emitted electron temperature significantly affects the sheath potential when the plasma electron temperature is within an order of magnitude of the emitted electron temperature. When the plasma electron temperature equals the emitted electron temperature the emissive sheath potential goes to zero. One dimensional particle-in-cell simulations corroborate the predictions made by this theory. The effects of the addition of a monoenergetic electron beam to the Maxwellian plasma electrons were explored, showing that the emissive sheath potential is close to the beam energy only when the emitted electron flux is less than the beam flux

  13. Preliminary scaling laws for plasma current, ion kinetic temperature, and plasma number density in the NASA Lewis bumpy torus plasma

    Science.gov (United States)

    Roth, J. R.

    1976-01-01

    Parametric variation of independent variables which may affect the characteristics of bumpy torus plasma have identified those which have a significant effect on the plasma current, ion kinetic temperature, and plasma number density, and those which do not. Empirical power law correlations of the plasma current, and the ion kinetic temperature and number density were obtained as functions of potential applied to the midplane electrode rings, the background neutral gas pressure, and the magnetic field strength. Additional parameters studied included the type of gas, the polarity of the midplane electrode rings, the mode of plasma operation, and the method of measuring the plasma number density. No significant departures from the scaling laws appear to occur at the highest ion kinetic temperatures or number densities obtained to date.

  14. [Study of enhancement effect of laser-induced crater on plasma radiation].

    Science.gov (United States)

    Chen, Jin-Zhong; Zhang, Xiao-Ping; Guo, Qing-Lin; Su, Hong-Xin; Li, Guang

    2009-02-01

    Single pulses exported from high-energy neodymium glass laser were used to act on the same position of soil sample surface repeatedly, and the plasma emission spectra generated from sequential laser pulse action were collected by spectral recording system. The experimental results show that the laser-induced soil plasma radiation was enhanced continuously under the confinement effect of the crater walls, and the line intensities and signal-to-background ratios both had different improvements along with increasing the number of acting pulses. The photographs of the plasma image and crater appearance were taken to study the plasma shape, laser-induced crater appearance, and the mass of the ablated sample. The internal mechanism behind that laser-induced crater enhanced plasma radiation was researched. Under the sequential laser pulse action, the forming plasma as a result enlarges gradually first, leading to distortion at the trail of plasma plume, and then, its volume diminishes slowly. And also, the color of the plasma changes from buff to white gradually, which implies that the temperature increases constantly. The laser-induced crater had a regular shape, that is, the diameter increased from its bottom to top gradually, thus forming a taper. The mass of the laser-ablated substance descends along with increasing the amount of action pulse. Atomization degree of vaporized substance was improved in virtue of the crater confinement effect, Fresnel absorption produced from the crater walls reflection, and the inverse bremsstrahlung, and the plasma radiation intensity was enhanced as a result.

  15. Solid density, low temperature plasma formation in a capillary discharge

    International Nuclear Information System (INIS)

    Kania, D.R.; Jones, L.A.; Maestas, M.D.; Shepherd, R.L.

    1987-01-01

    This work discusses the ability of the authors to produce solid density, low temperature plasmas in polyurethane capillary discharges. The initial capillary diameter is 20 μm. The plasma is produced by discharging a one Ohm parallel plate waterline and Marx generator system through the capillary. A peak current of 340 kA in 300 ns heats the inner wall of the capillary, and the plasma expands into the surrounding material. The authors studied the evolution of the discharge using current and voltage probes, axial and radial streak photography, axial x-ray diode array and schlieren photography, and have estimated the peak temperature of the discharge to be approximately 10 eV and the density to be near 10/sup 23/cm/sup -3/. This indicates that the plasma may approach the strongly coupled regime. They discuss their interpretation of the data and compare their results with theoretical models of the plasma dynamics

  16. Generator of the low-temperature heterogeneous plasma flow

    Science.gov (United States)

    Yusupov, D. I.; Gadzhiev, M. Kh; Tyuftyaev, A. S.; Chinnov, V. F.; Sargsyan, M. A.

    2018-01-01

    A generator of low-temperature dc plasma with an expanding channel of an output electrode for gas-thermal spraying was designed and constructed. The delivery of the sprayed powder into the cathode and anode arc-binding zones or into the plasma jet below the anode binding was realized. The electrophysical characteristics of both the plasma torch and the heterogeneous plasma flow with Al2O3 powder are studied. It is shown that the current-voltage characteristic (CVC) of a plasma torch depends on the gas flow rate. If the flow rate varies from 1 to 3 g/s, the falling CVC becomes gradually increasing. The speed and temperature of the sprayed powder are determined.

  17. Divertor, thermonuclear device and method of neutralizing high temperature plasma

    International Nuclear Information System (INIS)

    Ikegami, Hideo.

    1995-01-01

    The thermonuclear device comprises a thermonuclear reactor for taking place fusion reactions to emit fusion plasmas, and a divertor made of a hydrogen occluding material, and the divertor is disposed at a position being in contact with the fusion plasmas after nuclear fusion reaction. The divertor is heated by fusion plasmas after nuclear fusion reaction, and hydrogen is released from the hydrogen occluding material as a constituent material. A gas blanket is formed by the released hydrogen to cool and neutralize the supplied high temperature nuclear fusion plasmas. This prevents the high temperature plasmas from hitting against the divertor, elimination of the divertor by melting and evaporation, and solve a problem of processing a divertor activated by neutrons. In addition, it is possible to utilize hydrogen isotopes of fuels effectively and remove unnecessary helium. Inflow of impurities from out of the system can also be prevented. (N.H.)

  18. MICROWAVE NOISE MEASUREMENT OF ELECTRON TEMPERATURES IN AFTERGLOW PLASMAS

    Energy Technology Data Exchange (ETDEWEB)

    Leiby, Jr., C. C.; McBee, W. D.

    1963-10-15

    Transient electron temperatures in afterglow plasmas were determined for He (5 and 10 torr), Ne, and Ne plus or minus 5% Ar (2.4 and 24 torr) by combining measurements of plasma microwave noise power, and plasma reflectivity and absorptivity. Use of a low-noise parametric preamplifier permitted continuous detection during the afterglow of noise power at 5.5 Bc in a 1 Mc bandwidth. Electron temperature decays were a function of pressure and gas but were slower than predicted by electron energy loss mechanisms. The addition of argon altered the electron density decay in the neon afterglow but the electron temperature decay was not appreciably changed. Resonances in detected noise power vs time in the afterglow were observed for two of the three plasma waveguide geometries studied. These resonances correlate with observed resonances in absorptivity and occur over the same range of electron densities for a given geometry independent of gas type and pressure. (auth)

  19. Temperature Measurements of Dense Plasmas by Detailed Balance

    International Nuclear Information System (INIS)

    Holl, A; Redmer, R; Ropke, G; Reinholz, H; Thiele, R; Fortmann, C; Forster, E; Cao, L; Tschentscher, T; Toleikis, S; Glenzer, S H

    2006-01-01

    Plasmas at high electron densities of n e = 10 20 - 10 26 cm -3 and moderate temperatures T e = 1 - 20 eV are important for laboratory astrophysics, high energy density science and inertial confinement fusion. These plasmas are usually referred to as Warm Dense Matter (WDM) and are characterized by a coupling parameter of Λ ∼> 1 where correlations become important. The characterization of such plasmas is still a challenging task due to the lack of direct measurement techniques for temperatures and densities. They propose to measure the Thomson scattering spectrum of vacuum-UV radiation off density fluctuations in the plasma. Collective Thomson scattering provides accurate data for the electron temperature applying first principles. Further, this method takes advantage of the spectral asymmetry resulting from detailed balance and is independent of collisional effects in these dense systems

  20. Estimation of post disruption plasma temperature for fast current quench Aditya plasma shots

    International Nuclear Information System (INIS)

    Purohit, S.; Chowdhuri, M.B.; Joisa, Y.S.; Raval, J.V.; Ghosh, J.; Jha, R.

    2013-01-01

    Characteristics of tokamak current quenches are an important issue for the determination of electromagnetic forces that act on the in-vessel components and vacuum vessel during major disruptions. It is observed that thermal quench is followed by a sharp current decay. Fast current quench disruptive plasma shots were investigated for ADITYA tokamak. The current decay time was determined for the selected shots, which were in the range of 0.8 msec to 2.5 msec. This current decay information was then applied to L/R model, frequently employed for the estimation of the current decay time in tokamak plasmas, considering plasma inductance and plasma resistivity. This methodology was adopted for the estimation of the post disruption plasma temperature using the experimentally observed current decay time for the fast current quench disruptive ADITYA plasma shots. The study reveals that for the identified shots there is a constant increase in the current decay time with the post disruption plasma temperature. The investigations also explore the behavior post disruption plasma temperature and the current decay time as a function of the edge safety factor, Q. Post disruption plasma temperature and the current decay time exhibits a decrease with the increase in the value Q. (author)

  1. Enhanced laser beam coupling to a plasma

    International Nuclear Information System (INIS)

    Steiger, A.D.; Woods, C.H.

    1976-01-01

    Density perturbations are induced in a heated plasma by means of a pair of oppositely directed, polarized laser beams of the same frequency. The wavelength of the density perturbations is equal to one half the wavelength of the laser beams. A third laser beam is linearly polarized and directed at the perturbed plasma along a line that is perpendicular to the direction of the two opposed beams. The electric field of the third beam is oriented to lie in the plane containing the three beams. The frequency of the third beam is chosen to cause it to interact resonantly with the plasma density perturbations, thereby efficiently coupling the energy of the third beam to the plasma. 10 claims, 2 figures

  2. Nonlinear quantum fluid equations for a finite temperature Fermi plasma

    International Nuclear Information System (INIS)

    Eliasson, Bengt; Shukla, Padma K

    2008-01-01

    Nonlinear quantum electron fluid equations are derived, taking into account the moments of the Wigner equation and by using the Fermi-Dirac equilibrium distribution for electrons with an arbitrary temperature. A simplified formalism with the assumptions of incompressibility of the distribution function is used to close the moments in velocity space. The nonlinear quantum diffraction effects into the fluid equations are incorporated. In the high-temperature limit, we retain the nonlinear fluid equations for a dense hot plasma and in the low-temperature limit, we retain the correct fluid equations for a fully degenerate plasma

  3. Effect of finite ion-temperature on ion-acoustic solitary waves in an inhomogeneous plasma

    International Nuclear Information System (INIS)

    Shivamoggi, B.K.

    1981-01-01

    The propagation of weakly nonlinear ion-acoustic waves in an inhomogeneous plasma is studied taking into account the effect of finite ion temperature. It is found that, whereas both the amplitude and the velocity of propagation decrease as the ion-acoustic solitary wave propagates into regions of higher density, the effect of a finite ion temperature is to reduce the amplitude but enhance the velocity of propagation of the solitary wave. (author)

  4. Temperature measurement of plasma-assisted flames: comparison between optical emission spectroscopy and 2-color laser induced fluorescence techniques

    KAUST Repository

    Lacoste, Deanna A.

    2015-03-30

    Accurate thermometry of highly reactive environments, such as plasma-assisted combustion, is challenging. With the help of conical laminar premixed methane-air flames, this study compares two thermometry techniques for the temperature determination in a combustion front enhanced by nanosecond repetitively pulsed (NRP) plasma discharges. Based on emission spectroscopic analysis, the results show that the rotational temperature of CH(A) gives a reasonable estimate for the adiabatic flame temperature, only for lean and stoichiometric conditions. The rotational temperature of N2(C) is found to significantly underestimate the flame temperature. The 2-color OH-PLIF technique gives correct values of the flame temperature.

  5. Temperature measurement of plasma-assisted flames: comparison between optical emission spectroscopy and 2-color laser induced fluorescence techniques

    KAUST Repository

    Lacoste, Deanna A.; Heitz, Sylvain A.; Moeck, Jonas P.

    2015-01-01

    Accurate thermometry of highly reactive environments, such as plasma-assisted combustion, is challenging. With the help of conical laminar premixed methane-air flames, this study compares two thermometry techniques for the temperature determination in a combustion front enhanced by nanosecond repetitively pulsed (NRP) plasma discharges. Based on emission spectroscopic analysis, the results show that the rotational temperature of CH(A) gives a reasonable estimate for the adiabatic flame temperature, only for lean and stoichiometric conditions. The rotational temperature of N2(C) is found to significantly underestimate the flame temperature. The 2-color OH-PLIF technique gives correct values of the flame temperature.

  6. Continuous Emission Spectrum Measurement for Electron Temperature Determination in Low-Temperature Collisional Plasmas

    International Nuclear Information System (INIS)

    Liu Qiuyan; Li Hong; Chen Zhipeng; Xie Jinlin; Liu Wandong

    2011-01-01

    Continuous emission spectrum measurement is applied for the inconvenient diagnostics of low-temperature collisional plasmas. According to the physical mechanism of continuous emission, a simplified model is presented to analyze the spectrum in low temperature plasma. The validity of this model is discussed in a wide range of discharge parameters, including electron temperature and ionization degree. Through the simplified model, the continuous emission spectrum in a collisional argon internal inductively coupled plasma is experimentally measured to determine the electron temperature distribution for different gas pressures and radio-frequency powers. The inverse Abel transform is also applied for a better spatially resoluted results. Meanwhile, the result of the continuous emission spectrum measurement is compared to that of the electrostatic double probes, which indicates the effectiveness of this method. (low temperature plasma)

  7. Growth and characterization of titanium oxide by plasma enhanced atomic layer deposition

    KAUST Repository

    Zhao, Chao; Hedhili, Mohamed N.; Li, Jingqi; Wang, Qingxiao; Yang, Yang; Chen, Long; LI, LIANG

    2013-01-01

    The growth of TiO2 films by plasma enhanced atomic layer deposition using Star-Ti as a precursor has been systematically studied. The conversion from amorphous to crystalline TiO2 was observed either during high temperature growth or annealing

  8. Enhancement of plasma generation in catalyst pores with different shapes

    Science.gov (United States)

    Zhang, Yu-Ru; Neyts, Erik C.; Bogaerts, Annemie

    2018-05-01

    Plasma generation inside catalyst pores is of utmost importance for plasma catalysis, as the existence of plasma species inside the pores affects the active surface area of the catalyst available to the plasma species for catalytic reactions. In this paper, the electric field enhancement, and thus the plasma production inside catalyst pores with different pore shapes is studied with a two-dimensional fluid model. The results indicate that the electric field will be significantly enhanced near tip-like structures. In a conical pore with small opening, the strongest electric field appears at the opening and bottom corners of the pore, giving rise to a prominent ionization rate throughout the pore. For a cylindrical pore, the electric field is only enhanced at the bottom corners of the pore, with lower absolute value, and thus the ionization rate inside the pore is only slightly enhanced. Finally, in a conical pore with large opening, the electric field is characterized by a maximum at the bottom of the pore, yielding a similar behavior for the ionization rate. These results demonstrate that the shape of the pore has a significantly influence on the electric field enhancement, and thus modifies the plasma properties.

  9. High Temperature Plasmas Theory and Mathematical Tools for Laser and Fusion Plasmas

    CERN Document Server

    Spatschek, Karl-Heinz

    2012-01-01

    Filling the gap for a treatment of the subject as an advanced course in theoretical physics with a huge potential for future applications, this monograph discusses aspects of these applications and provides theoretical methods and tools for their investigation. Throughout this coherent and up-to-date work the main emphasis is on classical plasmas at high-temperatures, drawing on the experienced author's specialist background. As such, it covers the key areas of magnetic fusion plasma, laser-plasma-interaction and astrophysical plasmas, while also including nonlinear waves and phenomena.

  10. [Spectroscopic diagnostics of high temperature plasmas

    International Nuclear Information System (INIS)

    Moos, W.

    1989-01-01

    A research program in soft x-ray/ultraviolet/visible diagnostics for magnetic fusion is described. Recent results include the electron temperature, electron density and impurity densities during EML activity on the TEXT tokamak. The Zeeman effect induced circular polarization in Li neutral beam emissions has been analyzed to determine the safety factor in sawtoothing and ECRH heated discharge. The reflective properties of multilayer mirrors (10-200 Angstrom) were measured. Future work includes an order of magnitude improvement in the time resolution of the circular-polarimeter, development of a soft x-ray normal incidence spectrometer and a feasibility study for a narrow band x-ray photometer

  11. Microwave remote plasma enhanced-atomic layer deposition system with multicusp confinement chamber.

    Science.gov (United States)

    Dechana, A; Thamboon, P; Boonyawan, D

    2014-10-01

    A microwave remote Plasma Enhanced-Atomic Layer Deposition system with multicusp confinement chamber is established at the Plasma and Beam Physics research facilities, Chiang Mai, Thailand. The system produces highly-reactive plasma species in order to enhance the deposition process of thin films. The addition of the multicusp magnetic fields further improves the plasma density and uniformity in the reaction chamber. Thus, the system is more favorable to temperature-sensitive substrates when heating becomes unwanted. Furthermore, the remote-plasma feature, which is generated via microwave power source, offers tunability of the plasma properties separately from the process. As a result, the system provides high flexibility in choice of materials and design experiments, particularly for low-temperature applications. Performance evaluations of the system were carried on coating experiments of Al2O3 layers onto a silicon wafer. The plasma characteristics in the chamber will be described. The resulted Al2O3 films-analyzed by Rutherford Backscattering Spectrometry in channeling mode and by X-ray Photoelectron Spectroscopy techniques-will be discussed.

  12. Microwave remote plasma enhanced-atomic layer deposition system with multicusp confinement chamber

    Energy Technology Data Exchange (ETDEWEB)

    Dechana, A. [Program of Physics and General Science, Faculty of Science and Technology, Songkhla Rajabhat University, Songkhla 90000 (Thailand); Thamboon, P. [Science and Technology Research Institute, Chiang Mai University, Chiang Mai 50200 (Thailand); Boonyawan, D., E-mail: dheerawan.b@cmu.ac.th [Plasma and Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

    2014-10-15

    A microwave remote Plasma Enhanced-Atomic Layer Deposition system with multicusp confinement chamber is established at the Plasma and Beam Physics research facilities, Chiang Mai, Thailand. The system produces highly-reactive plasma species in order to enhance the deposition process of thin films. The addition of the multicusp magnetic fields further improves the plasma density and uniformity in the reaction chamber. Thus, the system is more favorable to temperature-sensitive substrates when heating becomes unwanted. Furthermore, the remote-plasma feature, which is generated via microwave power source, offers tunability of the plasma properties separately from the process. As a result, the system provides high flexibility in choice of materials and design experiments, particularly for low-temperature applications. Performance evaluations of the system were carried on coating experiments of Al{sub 2}O{sub 3} layers onto a silicon wafer. The plasma characteristics in the chamber will be described. The resulted Al{sub 2}O{sub 3} films—analyzed by Rutherford Backscattering Spectrometry in channeling mode and by X-ray Photoelectron Spectroscopy techniques—will be discussed.

  13. Microwave remote plasma enhanced-atomic layer deposition system with multicusp confinement chamber

    Science.gov (United States)

    Dechana, A.; Thamboon, P.; Boonyawan, D.

    2014-10-01

    A microwave remote Plasma Enhanced-Atomic Layer Deposition system with multicusp confinement chamber is established at the Plasma and Beam Physics research facilities, Chiang Mai, Thailand. The system produces highly-reactive plasma species in order to enhance the deposition process of thin films. The addition of the multicusp magnetic fields further improves the plasma density and uniformity in the reaction chamber. Thus, the system is more favorable to temperature-sensitive substrates when heating becomes unwanted. Furthermore, the remote-plasma feature, which is generated via microwave power source, offers tunability of the plasma properties separately from the process. As a result, the system provides high flexibility in choice of materials and design experiments, particularly for low-temperature applications. Performance evaluations of the system were carried on coating experiments of Al2O3 layers onto a silicon wafer. The plasma characteristics in the chamber will be described. The resulted Al2O3 films—analyzed by Rutherford Backscattering Spectrometry in channeling mode and by X-ray Photoelectron Spectroscopy techniques—will be discussed.

  14. Microwave remote plasma enhanced-atomic layer deposition system with multicusp confinement chamber

    International Nuclear Information System (INIS)

    Dechana, A.; Thamboon, P.; Boonyawan, D.

    2014-01-01

    A microwave remote Plasma Enhanced-Atomic Layer Deposition system with multicusp confinement chamber is established at the Plasma and Beam Physics research facilities, Chiang Mai, Thailand. The system produces highly-reactive plasma species in order to enhance the deposition process of thin films. The addition of the multicusp magnetic fields further improves the plasma density and uniformity in the reaction chamber. Thus, the system is more favorable to temperature-sensitive substrates when heating becomes unwanted. Furthermore, the remote-plasma feature, which is generated via microwave power source, offers tunability of the plasma properties separately from the process. As a result, the system provides high flexibility in choice of materials and design experiments, particularly for low-temperature applications. Performance evaluations of the system were carried on coating experiments of Al 2 O 3 layers onto a silicon wafer. The plasma characteristics in the chamber will be described. The resulted Al 2 O 3 films—analyzed by Rutherford Backscattering Spectrometry in channeling mode and by X-ray Photoelectron Spectroscopy techniques—will be discussed

  15. The measurement of plasma temperature by height scattering

    International Nuclear Information System (INIS)

    Katzenstein, J.

    1976-04-01

    One of the most accurate methods for the determination of the electron and ion temperature of a plasma is the measurement of the spectrum of the light scattered from a monoshromatic laser beam by the plasma electrons. The simple case of uncorrelated electrons is treated in detail showing the scattered spectrum to be a simple Gaussian whose half-breadth is proportional to the mean electron thermal velocity hence the square root of electron temperature. The results of a more general treatment are also reviewed which takes into account electron-ion correlations. Experimental requirements on the laser, the spetral instrumentation, and the data analysis are discussed. (author)

  16. Low plasma edge temperatures for the self-pumped limiter

    International Nuclear Information System (INIS)

    Terry, W.K.; Brooks, J.N.

    1985-03-01

    Transport code calculations have been performed to study the operation of an INTOR-like tokamak plasma from which helium is removed by a self-pumped limiter, which traps helium, but not hydrogen, in its surface layers. To prevent saturation by helium, the surface is renewed by continuous injection of the surface material (vanadium in this study) into the scrape-off layer. The presence of the injected vanadium leads to plasma temperatures well below 50 eV in the scrape-off layer, with supplementary rf heating. Operation in this edge temperature regime is essential for the use of medium- and high-Z limiter coatings

  17. Low temperature plasma near a tokamak reactor limiter

    International Nuclear Information System (INIS)

    Braams, B.J.; Singer, C.E.

    1985-01-01

    Analytic and two-dimensional computational solutions for the plasma parameters near a toroidally symmetric limiter are illustrated for the projected parameters of a Tokamak Fusion Core Experiment (TFCX). The temperature near the limiter plate is below 20 eV, except when the density 10 cm inside the limiter contact is 8 x 10 13 cm -3 or less and the thermal diffusivity in the edge region is 2 x 10 4 cm 2 /s or less. Extrapolation of recent experimental data suggests that neither of these conditions is likely to be met near ignition in TFCX, so a low plasma temperature near the limiter should be considered a likely possibility

  18. Observation of high-temperature bubbles in an ECR plasma

    Science.gov (United States)

    Terasaka, K.; Yoshimura, S.; Tanaka, M. Y.

    2018-05-01

    Creation and annihilation of high-temperature bubbles have been observed in an electron cyclotron resonance plasma. The electron temperature in the bubble core is three times higher than that in the ambient region, and the size perpendicular to the magnetic field is much smaller than the plasma diameter. Formation of a bubble accompanies large negative spikes in the floating potential of a Langmuir probe, and the spatiotemporal behavior of the bubble has been visualized with a high-impedance wire grid detector. It is found that the bubble is in a prolate spheroidal shape with the axis along the magnetic field and occurs randomly in time and independently in space.

  19. Two dimensional radial gas flows in atmospheric pressure plasma-enhanced chemical vapor deposition

    Science.gov (United States)

    Kim, Gwihyun; Park, Seran; Shin, Hyunsu; Song, Seungho; Oh, Hoon-Jung; Ko, Dae Hong; Choi, Jung-Il; Baik, Seung Jae

    2017-12-01

    Atmospheric pressure (AP) operation of plasma-enhanced chemical vapor deposition (PECVD) is one of promising concepts for high quality and low cost processing. Atmospheric plasma discharge requires narrow gap configuration, which causes an inherent feature of AP PECVD. Two dimensional radial gas flows in AP PECVD induces radial variation of mass-transport and that of substrate temperature. The opposite trend of these variations would be the key consideration in the development of uniform deposition process. Another inherent feature of AP PECVD is confined plasma discharge, from which volume power density concept is derived as a key parameter for the control of deposition rate. We investigated deposition rate as a function of volume power density, gas flux, source gas partial pressure, hydrogen partial pressure, plasma source frequency, and substrate temperature; and derived a design guideline of deposition tool and process development in terms of deposition rate and uniformity.

  20. Room-temperature atmospheric pressure plasma plume for biomedical applications

    International Nuclear Information System (INIS)

    Laroussi, M.; Lu, X.

    2005-01-01

    As low-temperature nonequilibrium plasmas come to play an increasing role in biomedical applications, reliable and user-friendly sources need to be developed. These plasma sources have to meet stringent requirements such as low temperature (at or near room temperature), no risk of arcing, operation at atmospheric pressure, preferably hand-held operation, low concentration of ozone generation, etc. In this letter, we present a device that meets exactly such requirements. This device is capable of generating a cold plasma plume several centimeters in length. It exhibits low power requirements as shown by its current-voltage characteristics. Using helium as a carrier gas, very little ozone is generated and the gas temperature, as measured by emission spectroscopy, remains at room temperature even after hours of operations. The plasma plume can be touched by bare hands and can be directed manually by a user to come in contact with delicate objects and materials including skin and dental gum without causing any heating or painful sensation

  1. The plasma-wall interaction region: a key low temperature plasma for controlled fusion

    International Nuclear Information System (INIS)

    Counsell, G F

    2002-01-01

    The plasma-wall interaction region of a fusion device provides the interface between the hot core plasma and the material surfaces. To obtain acceptably low levels of erosion from these surfaces requires most of the power leaving the core to be radiated. This is accomplished in existing devices by encouraging plasma detachment, in which the hot plasma arriving in the region is cooled by volume recombination and ion-neutral momentum transfer with a dense population of neutrals recycled from the surface. The result is a low temperature (1 eV e e >10 19 m -3 ) but weakly ionized (n 0 >10 20 m -3 , n e /n 0 <0.1) plasma found nowhere else in the fusion environment. This plasma provides many of the conditions found in industrial plasmas exploiting plasma chemistry and the presence of carbon in the region (in the form of carbon-fibre composite used in the plasma facing materials) can result in the formation of deposited hydrocarbon films. The plasma-wall interaction region is therefore among the most difficult in fusion to model, requiring an understanding of atomic, molecular and surface physics issues

  2. The measurement of single particle temperature in plasma sprays

    International Nuclear Information System (INIS)

    Fincke, J.R.; Swank, W.D.; Bolsaitis, P.P.; Elliott, J.F.

    1990-01-01

    A measurement technique for simultaneously obtaining the size, velocity, temperature, and relative number density of particles entrained in high temperature flow fields is described. In determining the particle temperature from a two-color pyrometery technique, assumptions about the relative spectral emissivity of the particle are required. For situations in which the particle surface undergoes chemical reactions the assumption of grey body behavior is shown to introduce large Temperature measurement uncertainties. Results from isolated, laser heated, single particle measurements and in-flight data from the plasma spraying of WC-Co are presented. 10 refs., 5 figs

  3. Enhanced oxidation of naphthalene using plasma activation of TiO2/diatomite catalyst.

    Science.gov (United States)

    Wu, Zuliang; Zhu, Zhoubin; Hao, Xiaodong; Zhou, Weili; Han, Jingyi; Tang, Xiujuan; Yao, Shuiliang; Zhang, Xuming

    2018-04-05

    Non-thermal plasma technology has great potential in reducing polycyclic aromatic hydrocarbons (PAHs) emission. But in plasma-alone process, various undesired by-products are produced, which causes secondary pollutions. Here, a dielectric barrier discharge (DBD) reactor has been developed for the oxidation of naphthalene over a TiO 2 /diatomite catalyst at low temperature. In comparison to plasma-alone process, the combination of plasma and TiO 2 /diatomite catalyst significantly enhanced naphthalene conversion (up to 40%) and CO x selectivity (up to 92%), and substantially reduced the formation of aerosol (up to 90%) and secondary volatile organic compounds (up to near 100%). The mechanistic study suggested that the presence of the TiO 2 /diatomite catalyst intensified the electron energy in the DBD. Meantime, the energized electrons generated in the discharge activated TiO 2 , while the presence of ozone enhanced the activity of the TiO 2 /diatomite catalyst. This plasma-catalyst interaction led to the synergetic effect resulting from the combination of plasma and TiO 2 /diatomite catalyst, consequently enhanced the oxidation of naphthalene. Importantly, we have demonstrated the effectiveness of plasma to activate the photocatalyst for the deep oxidation of PAH without external heating, which is potentially valuable in the development of cost-effective gas cleaning process for the removal of PAHs in vehicle applications during cold start conditions. Copyright © 2017 Elsevier B.V. All rights reserved.

  4. Gas Temperature Measurement in a Glow Discharge Plasma

    Science.gov (United States)

    Sloneker, Kenneth; Podder, Nirmol; McCurdy, William E.; Shi, Shi

    2009-10-01

    In this study a relatively inexpensive quartz protected thermocouple is used to measure the gas temperature in the positive column of a glow discharge plasma. For simplicity a K-type thermocouple is used to interpret the gas temperature from the sensor voltage at pressures from 0.5 Torr to 15 Torr and discharge currents from 5 mA to 120 mA. Gas temperature is investigated as a function of the gas pressure at fixed discharge currents and as a function of discharge current at fixed gas pressures in three different gas species (Ar, N2, and He). An infinite cylinder model is used to compute the average gas temperature of the discharge from joule heating and gas thermal conductivity. The model and measurement data agree within 1% to 10% depending on plasma parameters. Data for all three gases have a similar quasi-linear increasing error as compared to the model.

  5. The Role of Molecules in Low Temperature Plasmas for Lighting

    International Nuclear Information System (INIS)

    Lapatovich, Walter P.

    2007-01-01

    High intensity discharge (HID) lamps are low temperature (∼0.5eV), weakly ionized plasmas sustained in a refractory but light transmissive envelope for the purpose of converting electrical power into visible radiation. For commercial applications this conversion must occur with good efficiency and with sufficient spectral content throughout the visible (380-780nm) to permit the light so generated to render colors in a fashion comparable to natural sunlight. These goals are often achieved by adding multiple metals to a basic mercury discharge. Because the vapor pressure of most metals is very much lower than mercury itself, chemical compounds containing the desired metals, and having higher vapor pressures are used to introduce the material into the basic discharge. Complexing agents which further improve the vapor pressure are used to enhance the amount of metals in the discharge. The metal compound and complexes are usually polyatomic species which vaporize and subsequently dissociate as they diffuse into the bulk plasma. Under the approximation of local thermodynamic equilibrium (LTE) the particles are in equilibrium, but not with the radiation Held. Strong thermal (106K/m) and density gradients are sustained in the discharge. Atomic and molecular radiation produced in the high temperature core transits through colder gas regions before exiting the lamp. In these regions where the complex molecular species exists in an undissociated state, bound-free transitions can result in energy being effectively converted from light radiation into heat in the mantle. Bound-bound transitions In Identifiable molecules can result in modification of the spectral output in unpredictable and counter-intuitive ways. Examples of completing agents and their effect on the spectral output of typical rare-earth containing HID lamps will be given. The melt composition and the complexing agents themselves may change with time, as chemical reactions in the lamp occur, and their benefit

  6. On improved understanding of plasma-chemical processes in complex low-temperature plasmas

    Science.gov (United States)

    Röpcke, Jürgen; Loffhagen, Detlef; von Wahl, Eric; Nave, Andy S. C.; Hamann, Stephan; van Helden, Jean-Piere H.; Lang, Norbert; Kersten, Holger

    2018-05-01

    Over the last years, chemical sensing using optical emission spectroscopy (OES) in the visible spectral range has been combined with methods of mid infrared laser absorption spectroscopy (MIR-LAS) in the molecular fingerprint region from 3 to 20 μm, which contains strong rotational-vibrational absorption bands of a large variety of gaseous species. This optical approach established powerful in situ diagnostic tools to study plasma-chemical processes of complex low-temperature plasmas. The methods of MIR-LAS enable to detect stable and transient molecular species in ground and excited states and to measure the concentrations and temperatures of reactive species in plasmas. Since kinetic processes are inherent to discharges ignited in molecular gases, high time resolution on sub-second timescales is frequently desired for fundamental studies as well as for process monitoring in applied research and industry. In addition to high sensitivity and good temporal resolution, the capacity for broad spectral coverage enabling multicomponent detection is further expanding the use of OES and MIR-LAS techniques. Based on selected examples, this paper reports on recent achievements in the understanding of complex low-temperature plasmas. Recently, a link with chemical modeling of the plasma has been provided, which is the ultimate objective for a better understanding of the chemical and reaction kinetic processes occurring in the plasma. Contribution to the Topical Issue "Fundamentals of Complex Plasmas", edited by Jürgen Meichsner, Michael Bonitz, Holger Fehske, Alexander Piel.

  7. Enhanced Design Alternative I: Low Temperature Design

    International Nuclear Information System (INIS)

    MacNeil, K.

    1999-01-01

    The purpose of this document is to evaluate Enhanced Design Alternative (EDA) 1, the low temperature repository design concept (CRWMS M and O 1999a). This technical document will provide supporting information for Site Recommendation (SR) and License Application (LA). Preparation of this evaluation will be in accordance with the technical document preparation plan (TDPP), (CRWMS M and O 1999b). EDA 1, one of five EDAs, was evolved from evaluation of a series of design features and alternatives developed during the first phase of the License Application Design Selection (LADS) process. Low, medium, and high temperature concepts were developed from the design features and alternatives prepared during Phase 1 of the LADS effort (CRWMS M and O 1999a). EDA 1 will first be evaluated against a single Screening Criterion, outlined in CRWMS M and O 1999a, which addresses post-closure performance of the repository. The performance of the repository is defined quantitatively as the peak radiological dose rate to an average individual of a critical group at a distance of 20 km from the repository site within 10,000 years. To satisfy this criterion the peak dose rate must not exceed the anticipated regulatory level of 25 mrem/yr within 10,000 years. If the EDA meets the screening criterion, the EDA will be further evaluated against the LADS Phase 2 Evaluation Criteria contained in CRWMS M and O 1999a

  8. Enhanced noise and Raman scattering in plasma

    International Nuclear Information System (INIS)

    Simon, A.; Short, R.W.

    1987-04-01

    Observations of Raman scattering from laser-produced plasma have shown a number of puzzling features. These can be explained by assuming the presence of a bump-on-tail electron distribution created by pulses of fast electrons arising from instabilities at the critical (n/sub c/) or the quarter-critical (n/sub c//4) surface. Experiments using thin foils, in which the target density drops below n/sub c/ and even n/sub c//4 early in the laser pulse, have continued to show the same agreement as is seen for thick targets between the observed Raman spectrum and the predictions of this theory. This raises the issue of the time scale on which such directed pulses of fast electrons can continue to exist in the plasma after their source at n/sub c/ or n/sub c//4 disappears. We show that the classical degradation process is quite slow (of the order of 100 ps or more). Collective processes would appear to broaden and flatten the beam on a faster time scale. However, inclusion of finite spatial size strongly reduces the effect. Furthermore, we will show that broadening of the beam has little effect on the predicted spectrum

  9. Ultrasound enhanced plasma surface modification at atmospheric pressure

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Singh, Shailendra Vikram; Norrman, Kion

    and the material surface, and thus many reactive species generated in the plasma can reach the surface before inactivated, and be efficiently utilized for surface modification. In the present work polyester plates are treated using a dielectric barrier discharge (DBD) and a gliding arc at atmospheric pressure......Atmospheric pressure plasma treatment can be highly enhanced by simultaneous high-power ultrasonic irradiation onto the treating surface. It is because ultrasonic waves with a sound pressure level (SPL) above approximately 140 dB can reduce the thickness of a boundary gas layer between the plasma...... irradiation, the water contact angle dropped markedly, and tended to decrease furthermore at higher power. The ultrasonic irradiation during the plasma treatment consistently improved the wettability. Oxygen containing polar functional groups were introduced at the surface by the plasma treatment...

  10. Study on low temperature plasma driven permeation of hydrogen

    Energy Technology Data Exchange (ETDEWEB)

    Takizawa, Masayuki [Japan Atomic Energy Research Inst., Tokai, Ibaraki (Japan). Tokai Research Establishment

    1998-03-01

    It is one of the most important problem in PWI of fusion devices from the point of view of tritium leakage that hydrogen diffuses in the wall of the device and permeates through it, which results in hydrogen being released to the coolant side. In this study, plasma driven permeation experiments were carried out with several kinds of metal membranes in the low temperature plasma where ionic and atomic hydrogen as well as electron existed in order to survey PDP mechanism from the many view points. In addition, incident flux rate from the plasma to the membrane surface was evaluated by calculation analysis. As a result the mechanism of low temperature PDP was found out and described as PDP models. The simulation of the membrane pump system was executed and the system performance was estimated with the models. (author). 135 refs.

  11. Study on low temperature plasma driven permeation of hydrogen

    International Nuclear Information System (INIS)

    Takizawa, Masayuki

    1998-03-01

    It is one of the most important problem in PWI of fusion devices from the point of view of tritium leakage that hydrogen diffuses in the wall of the device and permeates through it, which results in hydrogen being released to the coolant side. In this study, plasma driven permeation experiments were carried out with several kinds of metal membranes in the low temperature plasma where ionic and atomic hydrogen as well as electron existed in order to survey PDP mechanism from the many view points. In addition, incident flux rate from the plasma to the membrane surface was evaluated by calculation analysis. As a result the mechanism of low temperature PDP was found out and described as PDP models. The simulation of the membrane pump system was executed and the system performance was estimated with the models. (author). 135 refs

  12. Scalar perturbations in two-temperature cosmological plasmas

    NARCIS (Netherlands)

    Moortgat, J.B.; Marklund, M.

    2006-01-01

    We study the properties of density perturbations of a two-component plasma with a temperature difference on a homogeneous and isotropic background. For this purpose, we extend the general relativistic gauge-invariant and covariant (GIC) perturbation theory to include a multifluid with a particular

  13. Solitary ionizing surface waves on low-temperature plasmas

    International Nuclear Information System (INIS)

    Vladimirov, S.V.; Yu, M.Y.

    1993-01-01

    It is demonstrated that at the boundary of semi-infinite low-temperature plasma new types of localized ionizing surface wave structures can propagate. The solitary waves are described by an evolution equation similar to the KdV equation, but the solutions differ considerably from that of the latter

  14. Electrostatic and electromagnetic traps for high-temperature plasma

    International Nuclear Information System (INIS)

    Lavrent'ev, O.A.

    Theoretical and experimental aspects of thermal isolation are considered for a high-temperature plasma in systems with electrostatic as well as electric and magnetic fields. Specific types of traps are discussed, together with diagnostic methods and fundamental experimental results. (U.S.)

  15. Emission spectroscopy of highly ionized high-temperature plasma jets

    Energy Technology Data Exchange (ETDEWEB)

    Belevtsev, A A; Chinnov, V F; Isakaev, E Kh [Associated Institute for High Temperatures, Russian Academy of Sciences Izhorskaya 13/19, Moscow, 125412 (Russian Federation)

    2006-08-01

    This paper deals with advanced studies on the optical emission spectroscopy of atmospheric pressure highly ionized high-temperature argon and nitrogen plasma jets generated by a powerful arc plasmatron. The emission spectra are taken in the 200-1000 nm range with a spectral resolution of {approx}0.01-0.02 nm. The exposure times are 6 x 10{sup -6}-2 x 10{sup -2} s, the spatial resolution is 0.02-0.03 mm. The recorded jet spectra are abundant in spectral lines originating from different ionization stages. In nitrogen plasmas, tens of vibronic bands are also observed. To interpret and process these spectra such that plasma characteristics can be derived, a purpose-developed automated processing system is applied. The use of a CCD camera at the spectrograph output allows a simultaneous recording of the spectral and chord intensity distributions of spectral lines, which can yet belong to the overlapped spectra of the first and second orders of interference. The modern optical diagnostic means and methods used permit the determination of spatial distributions of electron number densities and temperatures and evaluation of rotational temperatures. The radial profiles of the irradiating plasma components can also be obtained. Special attention is given to the method of deriving rotational temperatures using vibronic bands with an incompletely identified rotational structure.

  16. Dual – Temperature Electron distribution in a Laboratory Plasma ...

    African Journals Online (AJOL)

    The dual-temperature distribution function is used to investigate theoretically the effect of a perturbation of Maxwell distribution function on density ratios in a laboratory plasma produced solely by collision. By assuming a foreknowledge of collision coefficients and cross-sections and an atomic model which sets at two ...

  17. Ultrasound enhanced plasma surface modification at atmospheric pressure

    DEFF Research Database (Denmark)

    Kusano, Yukihiro; Singh, Shailendra Vikram; Norrman, Kion

    2012-01-01

    Efficiency of atmospheric pressure plasma treatment can be highly enhanced by simultaneous high power ultrasonic irradiation onto the treating surface. It is because ultrasonic waves with a sound pressure level (SPL) above ∼140 dB can reduce the thickness of a boundary gas layer between the plasma...... arc at atmospheric pressure to study adhesion improvement. The effect of ultrasonic irradiation with the frequency diapason between 20 and 40 kHz at the SPL of ∼150 dB was investigated. After the plasma treatment without ultrasonic irradiation, the wettability was significantly improved...

  18. Control of ordered mesoporous titanium dioxide nanostructures formed using plasma enhanced glancing angle deposition

    Energy Technology Data Exchange (ETDEWEB)

    Gibson, Des [Institute of Thin Films, Sensors & Imaging, Scottish Universities Physics Alliance, University of West of Scotland, Paisley, PA1 2BE (United Kingdom); Child, David, E-mail: david.child@uws.ac.uk [Institute of Thin Films, Sensors & Imaging, Scottish Universities Physics Alliance, University of West of Scotland, Paisley, PA1 2BE (United Kingdom); Song, Shigeng; Zhao, Chao [Institute of Thin Films, Sensors & Imaging, Scottish Universities Physics Alliance, University of West of Scotland, Paisley, PA1 2BE (United Kingdom); Alajiani, Yahya [Institute of Thin Films, Sensors & Imaging, Scottish Universities Physics Alliance, University of West of Scotland, Paisley, PA1 2BE (United Kingdom); Department of Physics, Faculty of Science, Jazan University, Jazan (Saudi Arabia); Waddell, Ewan [Thin Film Solutions Ltd, West of Scotland Science Park, Glasgow, G20 0TH (United Kingdom)

    2015-10-01

    Three dimensional nanostructures of mesoporous (pore diameter between 2-50 nm) nanocrystalline titania (TiO{sub 2}) were produced using glancing angle deposition combined with plasma ion assisted deposition, providing plasma enhanced glancing angle deposition eliminating the need for post-annealing to achieve film crystallinity. Electron beam evaporation was chosen to deposit nanostructures at various azimuthal angles, achieving designed variation in three dimensional nanostructure. A thermionic broad beam hollow cathode plasma source was used to enhance electron beam deposition, with ability to vary in real time ion fluxes and energies providing a means to modify and control TiO{sub 2} nanostructure real time with controlled density and porosity along and lateral to film growth direction. Plasma ion assisted deposition was carried out at room temperature using a hollow cathode plasma source, ensuring low heat loading to the substrate during deposition. Plasma enhanced glancing angle TiO{sub 2} structures were deposited onto borosilicate microscope slides and used to characterise the effects of glancing angle and plasma ion energy distribution function on the optical and nanostructural properties. Variation in TiO{sub 2} refractive index from 1.40 to 2.45 (@ 550 nm) using PEGLAD is demonstrated. Results and analysis of the influence of plasma enhanced glancing angle deposition on evaporant path and resultant glancing angle deviation from standard GLAD are described. Control of mesoporous morphology is described, providing a means of optimising light trapping features and film porosity, relevant to applications such as fabrication of dye sensitised solar cells. - Highlights: • Plasma assistance during glancing angle deposition enables control of morphology. • Ion energy variation during glancing angle deposition varies columnar angle • Column thickness of glancing angle deposition dependant on ion current density • Ion current density variation during

  19. Plasma-enhanced atomic layer deposition of silicon dioxide films using plasma-activated triisopropylsilane as a precursor

    International Nuclear Information System (INIS)

    Jeon, Ki-Moon; Shin, Jae-Su; Yun, Ju-Young; Jun Lee, Sang; Kang, Sang-Woo

    2014-01-01

    The plasma-enhanced atomic layer deposition (PEALD) process was developed as a growth technique of SiO 2 thin films using a plasma-activated triisopropylsilane [TIPS, ((iPr) 3 SiH)] precursor. TIPS was activated by an argon plasma at the precursor injection stage of the process. Using the activated TIPS, it was possible to control the growth rate per cycle of the deposited films by adjusting the plasma ignition time. The PEALD technique allowed deposition of SiO 2 films at temperatures as low as 50 °C without carbon impurities. In addition, films obtained with plasma ignition times of 3 s and 10 s had similar values of root-mean-square surface roughness. In order to evaluate the suitability of TIPS as a precursor for low-temperature deposition of SiO 2 films, the vapor pressure of TIPS was measured. The thermal stability and the reactivity of the gas-phase TIPS with respect to water vapor were also investigated by analyzing the intensity changes of the C–H and Si–H peaks in the Fourier-transform infrared spectrum of TIPS

  20. Excitation temperature of a solution plasma during nanoparticle synthesis

    Energy Technology Data Exchange (ETDEWEB)

    Saito, Genki, E-mail: genki@eng.hokudai.ac.jp; Nakasugi, Yuki; Akiyama, Tomohiro [Center for Advanced Research of Energy and Materials, Hokkaido University, Sapporo 060-8628 (Japan)

    2014-08-28

    Excitation temperature of a solution plasma was investigated by spectroscopic measurements to control the nanoparticle synthesis. In the experiments, the effects of edge shielding, applied voltage, and electrode material on the plasma were investigated. When the edge of the Ni electrode wire was shielded by a quartz glass tube, the plasma was uniformly generated together with metallic Ni nanoparticles. The emission spectrum of this electrode contained OH, H{sub α}, H{sub β}, Na, O, and Ni lines. Without an edge-shielded electrode, the continuous infrared radiation emitted at the edge created a high temperature on the electrode surface, producing oxidized coarse particles as a result. The excitation temperature was estimated from the Boltzmann plot. When the voltages were varied at the edge-shielded electrode with low average surface temperature by using different electrolyte concentrations, the excitation temperature of current-concentration spots increased with an increase in the voltage. The size of the Ni nanoparticles decreased at high excitation temperatures. Although the formation of nanoparticles via melting and solidification of the electrode surface has been considered in the past, vaporization of the electrode surface could occur at a high excitation temperature to produce small particles. Moreover, we studied the effects of electrodes of Ti, Fe, Ni, Cu, Zn, Zr, Nb, Mo, Pd, Ag, W, Pt, Au, and various alloys of stainless steel and Cu–Ni alloys. With the exception of Ti, the excitation temperatures ranged from 3500 to 5500 K and the particle size depended on both the excitation temperature and electrode-material properties.

  1. Clearing of ventilating emissions in low temperature environment of plasma

    Science.gov (United States)

    Mansurov, R. Sh; Rafalskaya, T. A.

    2017-11-01

    The method of high-temperature processing of streams of the ventilating air which is a subject clearing from organic pollutions is developed. Data about its efficiency, including on a number of economic parameters are obtained. Results of work are recommended for use, first of all, by development clearing plasma-thermal reactors (CPTR) for clearing air, especially from toxic substances, and also for large technological clearing installations, containing organic ventilating emissions (OVE). It is created experimental CPTR. Laws of the expiration of a plasma jet in stream of OVE limited by cylindrical walls, water-cooled channel are experimentally investigated. Dependences of a trajectory and long-range the plasma jet blown radially in stream of OVE are received. Heat exchange of stream of OVE with walls of CPTR after blowing a plasma jet is experimentally investigated; dependences of distribution of temperatures on length of a reactor and a thermal stream in a wall of channel of CPTR are received. Are investigated chemical compound of OVE after plasma-thermal clearing, some experimental data by formation of oxides of nitrogen and mono-oxide of carbon during clearing are received.

  2. Plasma effects in aligned carbon nanoflake growth by plasma-enhanced hot filament chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Wang, B.B. [College of Chemistry and Chemical Engineering, Chongqing University of Technology, 69 Hongguang Rd, Lijiatuo, Banan District, Chongqing 400054 (China); Zheng, K. [Institute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing 100124 (China); Cheng, Q.J., E-mail: qijin.cheng@xmu.edu.cn [School of Energy Research, Xiamen University, Xiamen 361005 (China); Ostrikov, K. [Plasma Nanoscience Center Australia (PNCA), Manufacturing Flagship, Commonwealth Scientific and Industrial Research Organization, PO Box 218, Lindfield 2070, NSW (Australia); Institute for Future Environments and School of Chemistry, Physics and Mechanical Engineering, Queensland University of Technology, Brisbane 4000, QLD (Australia); Plasma Nanoscience, School of Physics, The University of Sydney, Sydney 2006, NSW (Australia)

    2015-01-15

    Highlights: • Plasma-specific effects in the growth of carbon nanoflakes (CNFs) are studied. • Electic field in the plasma sheath promotes separation of CNFs from the substrate. • The orentention of GNFs is related to the combined electic force and growth effects. • The high growth grates of aligned GNFs are plasma-related. - Abstract: Carbon nanofilms are directly grown on silicon substrates by plasma-enhanced hot filament chemical vapor deposition in methane environment. It is shown that the nanofilms are composed of aligned carbon nanoflakes by extensive investigation of experimental results of field emission scanning electron microscopy, micro-Raman spectroscopy and transmission electron microscopy. In comparison with the graphene-like films grown without plasmas, the carbon nanoflakes grow in an alignment mode and the growth rate of the films is increased. The effects of the plasma on the growth of the carbon nanofilms are studied. The plasma plays three main effects of (1) promoting the separation of the carbon nanoflakes from the silicon substrate, (2) accelerating the motion of hydrocarbon radicals, and (3) enhancing the deposition of hydrocarbon ions onto the substrate surface. Due to these plasma-specific effects, the carbon nanofilms can be formed from the aligned carbon nanoflakes with a high rate. These results advance our knowledge on the synthesis, properties and applications of graphene-based materials.

  3. 13. TOPICAL CONFERENCE ON HIGH TEMPERATURE PLASMA DIAGNOSTICS SCIENTIFIC PROGRAM

    International Nuclear Information System (INIS)

    Barnes, C.

    2000-01-01

    Electron cyclotron emission (ECE) has been employed as a standard electron temperature profile diagnostic on many tokamaks and stellarators, but most magnetically confined plasma devices cannot take advantage of standard ECE diagnostics to measure temperature. They are either overdense, operating at high density relative to the magnetic field (e.g. ω pe >> (Omega) ce in a spherical torus) or they have insufficient density and temperature to reach the blackbody condition (τ > 2). Electron Bernstein waves (EBWs) are electrostatic waves which can propagate in overdense plasmas and have a high optical thickness at the electron cyclotron resonance layers, as a result of their large K i . This talk reports on measurements of EBW emission on the CDX-U spherical torus, where B 0 ∼ 2 kG, e > ∼ 10 13 cm -3 and T e ∼ 10 - 200 eV. Results will be presented for both direct detection of EBWs and for mode-converted EBW emission. The EBW emission was absolutely calibrated and compared to the electron temperature profile measured by a multi-point Thomson scattering diagnostic. Depending on the plasma conditions, the mode-converted EBW radiation temperature was found to be ≤ T e and the emission source was determined to be radially localized at the electron cyclotron resonance layer. A Langmuir triple probe was employed to measure changes in edge density profile in the vicinity of the upper hybrid resonance where the mode conversion of the EBWs is expected to occur. Changes in the mode conversion efficiency may explain the observation of mode-converted EBW radiation temperatures below T e . Initial results suggest EBW emission and EBW heating are viable concepts for plasmas where ω pe >> (Omega) ce

  4. Foundations of modelling of nonequilibrium low-temperature plasmas

    Science.gov (United States)

    Alves, L. L.; Bogaerts, A.; Guerra, V.; Turner, M. M.

    2018-02-01

    This work explains the need for plasma models, introduces arguments for choosing the type of model that better fits the purpose of each study, and presents the basics of the most common nonequilibrium low-temperature plasma models and the information available from each one, along with an extensive list of references for complementary in-depth reading. The paper presents the following models, organised according to the level of multi-dimensional description of the plasma: kinetic models, based on either a statistical particle-in-cell/Monte-Carlo approach or the solution to the Boltzmann equation (in the latter case, special focus is given to the description of the electron kinetics); multi-fluid models, based on the solution to the hydrodynamic equations; global (spatially-average) models, based on the solution to the particle and energy rate-balance equations for the main plasma species, usually including a very complete reaction chemistry; mesoscopic models for plasma-surface interaction, adopting either a deterministic approach or a stochastic dynamical Monte-Carlo approach. For each plasma model, the paper puts forward the physics context, introduces the fundamental equations, presents advantages and limitations, also from a numerical perspective, and illustrates its application with some examples. Whenever pertinent, the interconnection between models is also discussed, in view of multi-scale hybrid approaches.

  5. Electron temperature gradient driven instability in the tokamak boundary plasma

    International Nuclear Information System (INIS)

    Xu, X.Q.; Rosenbluth, M.N.; Diamond, P.H.

    1992-01-01

    A general method is developed for calculating boundary plasma fluctuations across a magnetic separatrix in a tokamak with a divertor or a limiter. The slab model, which assumes a periodic plasma in the edge reaching the divertor or limiter plate in the scrape-off layer(SOL), should provide a good estimate, if the radial extent of the fluctuation quantities across the separatrix to the edge is small compared to that given by finite particle banana orbit. The Laplace transform is used for solving the initial value problem. The electron temperature gradient(ETG) driven instability is found to grow like t -1/2 e γmt

  6. Absolute decay parametric instability of high-temperature plasma

    International Nuclear Information System (INIS)

    Zozulya, A.A.; Silin, V.P.; Tikhonchuk, V.T.

    1986-01-01

    A new absolute decay parametric instability having wide spatial localization region is shown to be possible near critical plasma density. Its excitation is conditioned by distributed feedback of counter-running Langmuir waves occurring during parametric decay of incident and reflected pumping wave components. In a hot plasma with the temperature of the order of kiloelectronvolt its threshold is lower than that of a known convective decay parametric instability. Minimum absolute instability threshold is shown to be realized under conditions of spatial parametric resonance of higher orders

  7. Fluctuations in macroscopically agitated plasma:quasiparticles and effective temperature

    International Nuclear Information System (INIS)

    Sosenko, P.P.; Gresillon, D.

    1994-01-01

    Fluctuations in the plasma, in which macroscopic fluid-like motion is agitated due to large-scale and low-frequency electro-magnetic fields, are studied. Such fields can be produced by external factors or internally, for example due to turbulence. Fluctuation spectral distributions are calculated with regard to the renormalization of the transition probability for a test-particle and of the test-particle shielding. If the correlation length for the random fluid-like motion is large as compared to the fluctuation scale lengths, then the fluctuation spectral distributions can be explained in terms of quasiparticles originating from macroscopic plasma agitation and of an effective temperature

  8. Electron temperature measurements in lowdensity plasmas by helium spectroscopy

    International Nuclear Information System (INIS)

    Brenning, N.

    1977-09-01

    This method to use relative intensities of singlet and triplet lines of neutral helium to measure electron temperature in low-density plasmas is examined. Calculations from measured and theoretical data about transitions in neutral helium are carried out and compared to experimental results. It is found that relative intensities of singlet and triplet lines from neutral helium only can be used for TE determination in low-density, short-duration plasmas. The most important limiting processes are excitation from the metastable 2 3 S level and excitation transfer in collisions between electrons and excited helium atoms. An evaluation method is suggested, which minimizes the effect of these processes. (author)

  9. Electromagnetically induced transparency in high-temperature magnetoactive plasma

    International Nuclear Information System (INIS)

    Kryachko, A.Yu.; Litvak, A.G.; Tokman, M.D.

    2002-01-01

    The classical analog of the presently popular in the quantum electronics effect of the electromagnetically induced transparency (EIT) is studied. The EIT effect is considered for the electron-cyclotron waves in the plasma with the finite temperature. The expression for the effective index of the electromagnetic wave refraction is identified and the dispersion law and this wave absorption under the EIT conditions are studied. It is shown, that accounting for the thermal motion, which radically changes the behavior of the signal wave dispersion curves in the EIT area, as compared with the cold plasma case [ru

  10. Terahertz-Radiation-Enhanced Emission of Fluorescence from Gas Plasma

    International Nuclear Information System (INIS)

    Liu Jingle; Zhang, X.-C.

    2009-01-01

    We report the study of femtosecond laser-induced air plasma fluorescence under the illumination of terahertz (THz) pulses. Semiclassical modeling and experimental verification indicate that time-resolved THz radiation-enhanced emission of fluorescence is dominated by the electron kinetics and the electron-impact excitation of gas molecules or ions. We demonstrate that the temporal waveform of the THz field could be retrieved from the transient enhanced fluorescence, making omnidirectional, coherent detection available for THz time-domain spectroscopy.

  11. Plasma surface interactions in Q-enhanced mirror systems

    International Nuclear Information System (INIS)

    Post, R.F.

    1978-01-01

    Two approaches to enhancement of the Q (energy gain) factor of mirror systems are under study at Livermore. These include the Tandem Mirror and the Field Reversed Mirror. Both of these new ideas preserve features of conventional mirror systems as far as plasma-wall interactions are concerned. Specifically in both approaches field lines exit from the ends of the system and impinge on walls located at a distance from the confinement chamber. It is possible to predict some aspects of the plasma/surface interactions of TM and FRM systems from experience obtained in the Livermore 2XIIB experiment. In particular, as observed in 2XIIB, effective isolation of the plasma from thermal contact with the ends owing to the development of sheath-like regions is to be expected. Studies presently underway directed toward still further enhancing the decoupling of the plasma from the effects of plasma surface interactions at the walls will be discussed, with particular reference to the problem of minimizing the effects of refluxing secondary electrons produced by plasma impact on the end walls

  12. Enhanced surface functionality via plasma modification and plasma deposition techniques to create more biologically relevant materials

    Science.gov (United States)

    Shearer, Jeffrey C.

    Functionalizing nanoparticles and other unusually shaped substrates to create more biologically relevant materials has become central to a wide range of research programs. One of the primary challenges in this field is creating highly functionalized surfaces without modifying the underlying bulk material. Traditional wet chemistry techniques utilize thin film depositions to functionalize nanomaterials with oxygen and nitrogen containing functional groups, such as --OH and --NHx. These functional groups can serve to create surfaces that are amenable to cell adhesion or can act as reactive groups for further attachment of larger structures, such as macromolecules or antiviral agents. Additional layers, such as SiO2, are often added between the nanomaterial and the functionalized coating to act as a barrier films, adhesion layers, and to increase overall hydrophilicity. However, some wet chemistry techniques can damage the bulk material during processing. This dissertation examines the use of plasma processing as an alternative method for producing these highly functionalized surfaces on nanoparticles and polymeric scaffolds through the use of plasma modification and plasma enhanced chemical vapor deposition techniques. Specifically, this dissertation will focus on (1) plasma deposition of SiO2 barrier films on nanoparticle substrates; (2) surface functionalization of amine and alcohol groups through (a) plasma co-polymerization and (b) plasma modification; and (3) the design and construction of plasma hardware to facilitate plasma processing of nanoparticles and polymeric scaffolds. The body of work presented herein first examines the fabrication of composite nanoparticles by plasma processing. SiOxC y and hexylamine films were coated onto TiO2 nanoparticles to demonstrate enhanced water dispersion properties. Continuous wave and pulsed allyl alcohol plasmas were used to produce highly functionalized Fe2 O3 supported nanoparticles. Specifically, film composition was

  13. Absorption of CO2 laser light by a dense, high temperature plasma

    International Nuclear Information System (INIS)

    Peacock, N.J.; Forrest, M.J.; Morgan, P.D.; Offenberger, A.A.

    1977-01-01

    The interaction between a pulsed, CO 2 laser beam and the plasma produced in a plasma focus device is investigated theoretically and experimentally. The CO 2 laser radiation, directed orthogonal to the pinch axis and along the density gradient only weakly perturbs the focus since the radiation density of 30 J cm -3 (allowing for the Airy enhancement factor near the critical layer), is still less than the plasma thermal energy >=1 kJ cm -3 . On the contrary, the CO 2 laser beam is grossly affected by the plasma and absorption during the compressed pinch phase when the plasma frequency is much more complete than can be predicted by classical resistivity. Density fluctuations at the Langmuir frequency are measured directly for forward scattering from a probe, ruby laser beam. Since the wave numbers correspond to approximately 0.1 the Langmuir waves should appear as electron 'lines' in the scattered spectrum shifted by 427 A from the ruby laser wavelength. At low CO 2 laser pump intensity the electron wave intensity is close to the thermal level. As the pump is increased beyond a threshold of approximately 3x10 9 W/cm -2 (in vacuo) enhanced scattering is observed, reaching a factor of 30 above thermal. A WKB treatment of the electron-ion decay instability which takes into account the linear growth of waves at equal electron and ion temperatures and their convection in an inhomogeneous plasma is reasonably consistent with the observations

  14. The ionization length in plasmas with finite temperature ion sources

    Science.gov (United States)

    Jelić, N.; Kos, L.; Tskhakaya, D. D.; Duhovnik, J.

    2009-12-01

    The ionization length is an important quantity which up to now has been precisely determined only in plasmas which assume that the ions are born at rest, i.e., in discharges known as "cold ion-source" plasmas. Presented here are the results of our calculations of the ionization lengths in plasmas with an arbitrary ion source temperature. Harrison and Thompson (H&T) [Proc. Phys. Soc. 74, 145 (1959)] found the values of this quantity for the cases of several ion strength potential profiles in the well-known Tonks-Langmuir [Phys. Rev. 34, 876 (1929)] discharge, which is characterized by "cold" ion temperature. This scenario is also known as the "singular" ion-source discharge. The H&T analytic result covers cases of ion sources proportional to exp(βΦ) with Φ the normalized plasma potential and β =0,1,2 values, which correspond to particular physical scenarios. Many years following H&T's work, Bissell and Johnson (B&J) [Phys. Fluids 30, 779 (1987)] developed a model with the so-called "warm" ion-source temperature, i.e., "regular" ion source, under B&J's particular assumption that the ionization strength is proportional to the local electron density. However, it appears that B&J were not interested in determining the ionization length at all. The importance of this quantity to theoretical modeling was recognized by Riemann, who recently answered all the questions of the most advanced up-to-date plasma-sheath boundary theory with cold ions [K.-U. Riemann, Phys. Plasmas 13, 063508 (2006)] but still without the stiff warm ion-source case solution, which is highly resistant to solution via any available analytic method. The present article is an extension of H&T's results obtained for a single point only with ion source temperature Tn=0 to arbitrary finite ion source temperatures. The approach applied in this work is based on the method recently developed by Kos et al. [Phys. Plasmas 16, 093503 (2009)].

  15. Electron temperature determination in LTE and non-LTE plasmas

    International Nuclear Information System (INIS)

    Eddy, T.L.

    1983-01-01

    This article discusses how most experimental investigations assume a type of ''thermal equilibrium'' in which the excited levels are assumed to be populated according to the electron kinetic temperature, in the determination of electron temperature in LTE and non-LTE plasmas. This is justified on the basis that electron collisions dominate the equilibration of adjacent excited levels as shown by Byron, Stabler and Boartz. The comparison of temperature values calculated by various common methods as a check for local thermodynamic equilibrium (LTDE) or local thermal equilibrium (LTE) of the upper excited levels and the free electrons has been shown to indicate the excitation temperature in all cases utilized. Thomas shows that the source function of the first excited level may be dominated by non-local radiation, which would usually result in a different population than local collisional excitation would provide. Ionization from upper levels is by collisional means. The result may yield different valued excitation and electron temperatures

  16. Enhanced field emission from carbon nanotubes by hydrogen plasma treatment

    International Nuclear Information System (INIS)

    Zhi, C.Y.; Bai, X.D.; Wang, E.G.

    2002-01-01

    The field emission capability of the carbon nanotubes (CNTs) has been improved by hydrogen plasma treatment, and the enhanced emission mechanism has been studied systematically using Fourier-transform infrared spectroscopy, Raman, and transmission electron microscopy. The hydrogen concentration in the samples increases with increasing plasma treatment duration. A C δ- -H δ+ dipole layer may form on CNTs' surface and a high density of defects results from the plasma treatment, which is likely to make the external surface of CNTs more active to emit electrons after treatment. In addition, the sharp edge of CNTs' top, after removal of the catalyst particles, may increase the local electronic field more effectively. The present study suggests that hydrogen plasma treatment is a useful method for improving the field electron emission property of CNTs

  17. Enhanced Detection of Human Plasma Proteins on Nanostructured Silver Surfaces

    Directory of Open Access Journals (Sweden)

    Zuzana Orságová Králová

    2013-08-01

    enhancement factor of 3.6×102 was achieved for a band with a Raman shift of 2104cm‐1 for globulin deposited onto silver nanostructured film on unpolished stainless steel substrate. The detection limit was 400g/mL. Plasma or serum could present a preferable material for non‐ invasive cancer disease diagnosis using the SERS method.

  18. Confinement properties of JET plasmas with different temperature and density profiles

    International Nuclear Information System (INIS)

    Watkins, M.L.; Balet, B.; Bhatnagar, V.P.

    1989-01-01

    The confinement properties of plasmas with substantially different temperature and density profiles have been analysed. The effects of fast particles and energy pedestals on the overall confinement of plasma energy in limiter (L-mode) and X-point (L- and H-modes) discharges heated by NBI or ICRF or both are determined. The importance of the bootstrap current when such energy pedestals are formed is noted. Using sets of consistent experimental data, including ion temperature profile measurements, the local transport properties are compared in the L- and H-phases of a single null X-point medium density NBI heated discharge, the ''enhanced'' confinement phase of a limiter high density pellet-fuelled and ICRF heated discharge, the hot-ion phase of a double null X-point low density NBI heated discharge and the hot-ion and H-phases of a double null X-point low density high temperature NBI heated discharge. (author)

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

    Science.gov (United States)

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

    2015-11-01

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

  20. Non-equilibrium Microwave Plasma for Efficient High Temperature Chemistry.

    Science.gov (United States)

    van den Bekerom, Dirk; den Harder, Niek; Minea, Teofil; Gatti, Nicola; Linares, Jose Palomares; Bongers, Waldo; van de Sanden, Richard; van Rooij, Gerard

    2017-08-01

    A flowing microwave plasma based methodology for converting electric energy into internal and/or translational modes of stable molecules with the purpose of efficiently driving non-equilibrium chemistry is discussed. The advantage of a flowing plasma reactor is that continuous chemical processes can be driven with the flexibility of startup times in the seconds timescale. The plasma approach is generically suitable for conversion/activation of stable molecules such as CO2, N2 and CH4. Here the reduction of CO2 to CO is used as a model system: the complementary diagnostics illustrate how a baseline thermodynamic equilibrium conversion can be exceeded by the intrinsic non-equilibrium from high vibrational excitation. Laser (Rayleigh) scattering is used to measure the reactor temperature and Fourier Transform Infrared Spectroscopy (FTIR) to characterize in situ internal (vibrational) excitation as well as the effluent composition to monitor conversion and selectivity.

  1. Enhanced confinement in electron cyclotron resonance ion source plasma.

    Science.gov (United States)

    Schachter, L; Stiebing, K E; Dobrescu, S

    2010-02-01

    Power loss by plasma-wall interactions may become a limitation for the performance of ECR and fusion plasma devices. Based on our research to optimize the performance of electron cyclotron resonance ion source (ECRIS) devices by the use of metal-dielectric (MD) structures, the development of the method presented here, allows to significantly improve the confinement of plasma electrons and hence to reduce losses. Dedicated measurements were performed at the Frankfurt 14 GHz ECRIS using argon and helium as working gas and high temperature resistive material for the MD structures. The analyzed charge state distributions and bremsstrahlung radiation spectra (corrected for background) also clearly verify the anticipated increase in the plasma-electron density and hence demonstrate the advantage by the MD-method.

  2. Analysis of electron cyclotron emission spectra of high electron temperature, supershot plasmas in TFTR

    International Nuclear Information System (INIS)

    Taylor, G.; Arunasalam, V.; Efthimion, P.C.; Grek, B.

    1993-01-01

    A primary objective of the TFTR program since 1986 has been the study and optimization of deuterium Supershot plasmas. These plasmas are predominantly heated by 90-110 keV neutral deuterium beams (P NBI /P OH >30), central ion temperatures are ∝30 keV and central electron temperatures from ECE (T ECE ) often exceed 10 keV. Central electron temperature data measured with a TV Thomson scattering (TVTS) system (T TVTS ) during the period 1987-1990 have been compared with data from three different ECE instruments on TFTR. Although T ECE ∝T TVTS for temperatures below 6 keV, there is a systematically increasing disagreement at higher electron temperatures, with T ECE ∝1.2 T TVTS for T TVTS in the range 9-10 keV. Recent theoretical work on the ECE radiation temperature of non-equilibrium plasmas indicates that for a bi-Maxwellian electron velocity distribution with a ratio of tail to bulk electron density η, a bulk temperature T b , and a hot tail temperature T h , the perpendicular ECE radiation temperature is given by T ECE ∝T b {1+η(T h /T b )}, for η ECE would be enhanced over T TVTS by a factor which depends on η and T h . This paper investigates whether the discrepancy between T TVTS and T ECE seen in TFTR Supershots at high electron temperatures is due to the presence of a hot electron tail component. The extraordinary mode ECE spectrum at the second, third and fourth harmonics is measured on the horizontal midplane by an absolutely calibrated ECE Michelson interferometer. This ECE spectrum is compared with the output from a time-independent transport code with relativistic opacity which solves the three-dimensional ECE radiation transport in a toroidally symmetric, two-dimensional geometry and uses measured electron density and temperature profiles from the TVTS system. (orig.)

  3. Powder free PECVD epitaxial silicon by plasma pulsing or increasing the growth temperature

    Science.gov (United States)

    Chen, Wanghua; Maurice, Jean-Luc; Vanel, Jean-Charles; Cabarrocas, Pere Roca i.

    2018-06-01

    Crystalline silicon thin films are promising candidates for low cost and flexible photovoltaics. Among various synthesis techniques, epitaxial growth via low temperature plasma-enhanced chemical vapor deposition is an interesting choice because of two low temperature related benefits: low thermal budget and better doping profile control. However, increasing the growth rate is a tricky issue because the agglomeration of clusters required for epitaxy leads to powder formation in the plasma. In this work, we have measured precisely the time evolution of the self-bias voltage in silane/hydrogen plasmas at millisecond time scale, for different values of the direct-current bias voltage applied to the radio frequency (RF) electrode and growth temperatures. We demonstrate that the decisive factor to increase the epitaxial growth rate, i.e. the inhibition of the agglomeration of plasma-born clusters, can be obtained by decreasing the RF OFF time or increasing the growth temperature. The influence of these two parameters on the growth rate and epitaxial film quality is also presented.

  4. A High Temperature Liquid Plasma Model of the Sun

    Directory of Open Access Journals (Sweden)

    Robitaille P.-M.

    2007-01-01

    Full Text Available In this work, a liquid model of the Sun is presented wherein the entire solar mass is viewed as a high density/high energy plasma. This model challenges our current understanding of the densities associated with the internal layers of the Sun, advocating a relatively constant density, almost independent of radial position. The incompressible nature of liquids is advanced to prevent solar collapse from gravitational forces. The liquid plasma model of the Sun is a non-equilibrium approach, where nuclear reactions occur throughout the solar mass. The primary means of addressing internal heat transfer are convection and conduction. As a result of the convective processes on the solar surface, the liquid model brings into question the established temperature of the solar photosphere by highlighting a violation of Kirchhoff’s law of thermal emission. Along these lines, the model also emphasizes that radiative emission is a surface phenomenon. Evidence that the Sun is a high density/high energy plasma is based on our knowledge of Planckian thermal emission and condensed matter, including the existence of pressure ionization and liquid metallic hydrogen at high temperatures and pressures. Prior to introducing the liquid plasma model, the historic and scientific justifications for the gaseous model of the Sun are reviewed and the gaseous equations of state are also discussed.

  5. Radial Distribution Functions of Strongly Coupled Two-Temperature Plasmas

    Science.gov (United States)

    Shaffer, Nathaniel R.; Tiwari, Sanat Kumar; Baalrud, Scott D.

    2017-10-01

    We present tests of three theoretical models for the radial distribution functions (RDFs) in two-temperature strongly coupled plasmas. RDFs are useful in extending plasma thermodynamics and kinetic theory to strong coupling, but they are usually known only for thermal equilibrium or for approximate one-component model plasmas. Accurate two-component modeling is necessary to understand the impact of strong coupling on inter-species transport, e.g., ambipolar diffusion and electron-ion temperature relaxation. We demonstrate that the Seuferling-Vogel-Toeppfer (SVT) extension of the hypernetted chain equations not only gives accurate RDFs (as compared with classical molecular dynamics simulations), but also has a simple connection with the Yukawa OCP model. This connection gives a practical means to recover the structure of the electron background from knowledge of the ion-ion RDF alone. Using the model RDFs in Effective Potential Theory, we report the first predictions of inter-species transport coefficients of strongly coupled plasmas far from equilibrium. This work is supported by NSF Grant No. PHY-1453736, AFSOR Award No. FA9550-16-1-0221, and used XSEDE computational resources.

  6. Growth of highly oriented carbon nanotubes by plasma-enhanced hot filament chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Huang, Z.P.; Xu, J.W.; Ren, Z.F.; Wang, J.H. [Materials Synthesis Laboratory, Departments of Physics and Chemistry, and Center for Advanced Photonic and Electronic Materials (CAPEM), State University of New York at Buffalo, Buffalo, New York 14260 (United States); Siegal, M.P.; Provencio, P.N. [Sandia National Laboratories, Albuquerque, New Mexico 87185-1421 (United States)

    1998-12-01

    Highly oriented, multiwalled carbon nanotubes were grown on polished polycrystalline and single crystal nickel substrates by plasma enhanced hot filament chemical vapor deposition at temperatures below 666 {degree}C. The carbon nanotubes range from 10 to 500 nm in diameter and 0.1 to 50 {mu}m in length depending on growth conditions. Acetylene is used as the carbon source for the growth of the carbon nanotubes and ammonia is used for dilution gas and catalysis. The plasma intensity, acetylene to ammonia gas ratio, and their flow rates, etc. affect the diameters and uniformity of the carbon nanotubes. {copyright} {ital 1998 American Institute of Physics.}

  7. Radial convection of finite ion temperature, high amplitude plasma blobs

    DEFF Research Database (Denmark)

    Wiesenberger, M.; Madsen, Jens; Kendl, Alexander

    2014-01-01

    We present results from simulations of seeded blob convection in the scrape-off-layer of magnetically confined fusion plasmas. We consistently incorporate high fluctuation amplitude levels and finite Larmor radius (FLR) effects using a fully nonlinear global gyrofluid model. This is in line......-field transport compared to blobs simulated with the local model. The maximal blob amplitude is significantly higher in the global simulations than in the local ones. When the ion temperature is comparable to the electron temperature, global blob simulations show a reduced blob coherence and a decreased cross...

  8. Enhanced temperature-independent magnetoresistance below the ...

    Indian Academy of Sciences (India)

    The film exhibits a large nearly temperature-independent magnetoresistance around 99% in the temperature regime below p. The zero field-cooled (ZFC) and field-cooled (FC) magnetization data at 50 Oe shows irreversibility between the ZFC and FC close to the ferromagnetic transition temperature c = 250 K. The ZFC ...

  9. To the problem of electron temperature control in plasma

    International Nuclear Information System (INIS)

    Galechyan, G.A.; Anna, P.R.

    1995-01-01

    One of the main problems in low temperature plasma is control plasma parameters at fixed values of current and gas pressure in the discharge. It is known that an increase in the intensity of sound wave directed along the positive column to values in excess of a definite threshold leads to essential rise of the temperature of electrons. However, no less important is the reduction of electron temperature in the discharge down to the value less than that in plasma in the absence external influence. It is known that to reduce the electron temperature in the plasma of CO 2 laser, easily ionizable admixture are usually introduced in the discharge area with the view of increasing the overpopulation. In the present work we shall show that the value of electron temperature can be reduced by varying of sound wave intensity at its lower values. The experiment was performed on an experimental setup consisted of the tube with length 52 cm and diameter 9.8 cm, two electrodes placed at the distance of 27 cm from each other. An electrodynamical radiator of sound wave was fastened to one of tube ends. Fastened to the flange at the opposite end was a microphone for the control of sound wave parameters. The studies were performed in range of pressures from 40 to 180 Torr and discharge currents from 40 to 110 mA. The intensity of sound wave was varied from 74 to 92 dB. The measurement made at the first resonance frequency f = 150 Hz of sound in the discharge tube, at which a quarter of wave length keep within the length of the tube. The measurement of longitudinal electric field voltage in plasma of positive column was conducted with the help of two probes according to the compensation method. Besides, the measurement of gas temperature in the discharge were taken. Two thermocouple sensors were arranged at the distance of 8 cm from the anode, one of them being installed on the discharge tube axis, the second-fixed the tube wall

  10. To the problem of electron temperature control in plasma

    Energy Technology Data Exchange (ETDEWEB)

    Galechyan, G.A. [Institute of Applied Problem of Physics, Yerevan (Armenia); Anna, P.R. [Raritan Valley Community College, Somerville, NJ (United States)

    1995-12-31

    One of the main problems in low temperature plasma is control plasma parameters at fixed values of current and gas pressure in the discharge. It is known that an increase in the intensity of sound wave directed along the positive column to values in excess of a definite threshold leads to essential rise of the temperature of electrons. However, no less important is the reduction of electron temperature in the discharge down to the value less than that in plasma in the absence external influence. It is known that to reduce the electron temperature in the plasma of CO{sub 2} laser, easily ionizable admixture are usually introduced in the discharge area with the view of increasing the overpopulation. In the present work we shall show that the value of electron temperature can be reduced by varying of sound wave intensity at its lower values. The experiment was performed on an experimental setup consisted of the tube with length 52 cm and diameter 9.8 cm, two electrodes placed at the distance of 27 cm from each other. An electrodynamical radiator of sound wave was fastened to one of tube ends. Fastened to the flange at the opposite end was a microphone for the control of sound wave parameters. The studies were performed in range of pressures from 40 to 180 Torr and discharge currents from 40 to 110 mA. The intensity of sound wave was varied from 74 to 92 dB. The measurement made at the first resonance frequency f = 150 Hz of sound in the discharge tube, at which a quarter of wave length keep within the length of the tube. The measurement of longitudinal electric field voltage in plasma of positive column was conducted with the help of two probes according to the compensation method. Besides, the measurement of gas temperature in the discharge were taken. Two thermocouple sensors were arranged at the distance of 8 cm from the anode, one of them being installed on the discharge tube axis, the second-fixed the tube wall.

  11. Characterizations of atmospheric pressure low temperature plasma jets and their applications

    Science.gov (United States)

    Karakas, Erdinc

    2011-12-01

    Atmospheric pressure low temperature plasma jets (APLTPJs) driven by short pulses have recently received great attention because of their potential in biomedical and environmental applications. This potential is due to their user-friendly features, such as low temperature, low risk of arcing, operation at atmospheric pressure, easy handheld operation, and low concentration of ozone generation. Recent experimental observations indicate that an ionization wave exists and propagates along the plasma jet. The plasma jet created by this ionization wave is not a continuous medium but rather consists of a bullet-like-structure known as "Plasma Bullet". More interestingly, these plasma bullets actually have a donut-shaped makeup. The nature of the plasma bullet is especially interesting because it propagates in the ambient air at supersonic velocities without any externally applied electric field. In this dissertation, experimental insights are reported regarding the physical and chemical characteristics of the APLTPJs. The dynamics of the plasma bullet are investigated by means of a high-speed ICCD camera. A plasma bullet propagation model based on the streamer theory is confirmed with adequate explanations. It is also found that a secondary discharge, ignited by the charge accumulation on the dielectric electrode surfaces at the end of the applied voltage, interrupts the plasma bullet propagation due to an opposing current along the ionization channel. The reason for this interesting phenomenon is explained in detail. The plasma bullet comes to an end when the helium mole fraction along the ionization channel, or applied voltage, or both, are less than some critical values. The presence of an inert gas channel in the surrounding air, such as helium or argon, has a critical role in plasma bullet formation and propagation. For this reason, a fluid dynamics study is employed by a commercially available simulation software, COMSOL, based on finite element method. Spatio

  12. Cesium-plasma-conductivity enhancement in the advanced thermionic energy converter. Final report

    International Nuclear Information System (INIS)

    Manikopoulos, C.N.

    Two methods of plasma conductivity enhancement in a cesium vapor thermionic energy converter have been studied. The first involved resonance photoabsorption of several cesium lines and the second utilized cesium plasma sustenance by application of microwave power. An extensive study of ionization processes in a cesium discharge in the presence of resonance ionization was made. Calculations were made of expected percentage excitation levels for several cesium resonance transitions for different values of neutral density and temperature as well as incident radiation power levels. The results of some of these computations were tabulated. Several ionization schemes were considered. A number of cesium transitions were investigated in the range of 799 to 870 nanometers for four different cesium reservoir temperatures, 467, 511, 550 and 591 K. The related absorption coefficients of the radiation lines in the plasma were deduced and tabulated. The resulting plasma conductivity increase was recorded and the associated ionization enhancement was deduced. A microwave cavity was built where the emitter and collector of a simple thermionic converter made up two of the cavity walls and resonant microwave power was externally applied. The I-V characteristics of the thermionic converter were studied under several microwave power levels in the range of 0 to 2 watts. Significant shifts to higher currents were observed as the microwave power levels were raised. In conclusion, both methods show promise as auxiliary ionization mechanisms for the thermionic energy converter, especially at low emitter temperatures

  13. Branched carbon nanofiber network synthesis at room temperature using radio frequency supported microwave plasmas

    International Nuclear Information System (INIS)

    Boskovic, Bojan O.; Stolojan, Vlad; Zeze, Dagou A.; Forrest, Roy D.; Silva, S. Ravi P.; Haq, Sajad

    2004-01-01

    Carbon nanofibers have been grown at room temperature using a combination of radio frequency and microwave assisted plasma-enhanced chemical vapor deposition. The nanofibers were grown, using Ni powder catalyst, onto substrates kept at room temperature by using a purposely designed water-cooled sample holder. Branched carbon nanofiber growth was obtained without using a template resulting in interconnected carbon nanofiber network formation on substrates held at room temperature. This method would allow room-temperature direct synthesized nanofiber networks over relatively large areas, for a range of temperature sensitive substrates, such as organic materials, plastics, and other polymers of interest for nanoelectronic two-dimensional networks, nanoelectromechanical devices, nanoactuators, and composite materials

  14. Low Temperature Plasma for the Treatment of Epithelial Cancer Cells

    Science.gov (United States)

    Mohades, Soheila

    Biomedical applications of low temperature plasmas (LTP) may lead to a paradigm shift in treating various diseases by conducting fundamental research on the effects of LTP on cells, tissues, organisms (plants, insects, and microorganisms). This is a rapidly growing interdisciplinary research field that involves engineering, physics, life sciences, and chemistry to find novel solutions for urgent medical needs. Effects of different LTP sources have shown the anti-tumor properties of plasma exposure; however, there are still many unknowns about the interaction of plasma with eukaryotic cells which must be elucidated in order to evaluate the practical potential of plasma in cancer treatment. Plasma, the fourth state of matter, is composed of electrons, ions, reactive molecules (radicals and non-radicals), excited species, radiation, and heat. A sufficient dose (time) of plasma exposure can induce death in cancer cells. The plasma pencil is employed to study the anti-tumor properties of this treatment on epithelial cells. The plasma pencil has been previously used for the inactivation of bacteria, destroying amyloid fibrils, and the killing of various cancer cells. Bladder cancer is the 9th leading cause of cancer. In this dissertation, human urinary bladder tissue with the squamous cell carcinoma disease (SCaBER cells) is treated with LTP utilizing two different approaches: direct plasma exposure and Plasma Activated Media (PAM) as an advancement to the treatment. PAM is produced by exposing a liquid cell culture medium to the plasma pencil. Direct LTP treatment of cancer cells indicates a dose-dependent killing effect at post-treatment times. Similarly, PAM treatment shows an anti-cancer effect by inducing substantial cell death. Reactive oxygen species (ROS) and reactive nitrogen species (RNS) have an important role in the biomedical effects of LTP treatment. This study demonstrates the capability of the plasma pencil to transport ROS/RNS into cell culture media

  15. Physical properties of dense, low-temperature plasmas

    International Nuclear Information System (INIS)

    Redmer, R.

    1997-01-01

    Plasmas occur in a wide range of the density-temperature plane. The physical quantities can be expressed by Green's functions which are evaluated by means of standard quantum statistical methods. The influences of many-particle effects such as dynamic screening and self-energy, structure factor and local-field corrections, formation and decay of bound states, degeneracy and Pauli exclusion principle are studied. As a basic concept for partially ionized plasmas, a cluster decomposition is performed for the self-energy as well as for the polarization function. The general model of a partially ionized plasma interpolates between low-density, nonmetallic systems such as atomic vapors and high-density, conducting systems such as metals or fully ionized plasmas. The equations of state, including the location of the critical point and the shape of the coexistence curve, are determined for expanded alkali-atom and mercury fluids. The occurrence of a metal-nonmetal transition near the critical point of the liquid-vapor phase transition leads in these materials to characteristic deviations from the behavior of nonconducting fluids such as the inert gases. Therefore, a unified approach is needed to describe the drastic changes of the electronic properties as well as the variation of the physical properties with the density. Similar results are obtained for the hypothetical plasma phase transition in hydrogen plasma. The transport coefficients (electrical and thermal conductivity, thermopower) are studied wthin linear response theory given here in the formulation of Zubarev which is valid for arbitrary degeneracy and yields the transport coefficients for the limiting cases of nondegenerate, weakly coupled plasmas (Spitzer theory) as well as degenerate, strongly coupled plasmas (Ziman theory). mercury within the MHNC scheme via effective ion-ion potentials which are derived from the polarization function within an extended RPA. The optical properties of dense plasmas, the shift

  16. Enhancing Cold Atmospheric Plasma Treatment Efficiency for Cancer Therapy

    Science.gov (United States)

    Cheng, Xiaoqian

    To improve efficiency and safety of anti-cancer therapies the researchers and clinicians alike are prompted to develop targeted combined therapies that especially minimize damage to healthy tissues while eradicating the body of cancerous tissues. Previous research in cold atmospheric plasma (CAP) and cancer cell interaction has repeatedly proven that cold plasma induced cell death. In this study, we seek to integrate the medical application of CAP. We proposed and implemented 3 novel ideas to enhance efficacy and selectivity of cancer therapy. It is postulated that the reactive oxygen species (ROS) and reactive nitrogen species (RNS) play a major role in the CAP cancer therapy. We determined a mechanism of CAP therapy on glioblastoma cells (U87) through an understanding of the composition of CAP, including output voltage, treatment time, and gas flow-rate. We varied the characteristics of the cold plasma in order to obtain different major species (such as O, OH, N2+, and N2 lines). "plasma dosage" D ~ Q * V * t. is defined, where D is the entire "plasma dosage"; Q is the flow rate of feeding gas; V is output voltage; t is treatment time. The proper CAP dosage caused 3-fold cell death in the U87 cells compared to the normal human astrocytes E6/E7 cells. We demonstrated there is a synergy between AuNPS and CAP in cancer therapy. Specifically, the concentration of AuNPs plays an important role on plasma therapy. At an optimal concentration, gold nanoparticles can significantly induce U87 cell death up to a 30% overall increase compared to the control group with the same plasma dosage but no AuNPs applied. The ROS intensity of the corresponding conditions has a reversed trend compared to cell viability. This matches with the theory that intracellular ROS accumulation results in oxidative stress, which further changes the intracellular pathways, causing damage to the proteins, lipids and DNA. Our results show that this synergy has great potential in improving the

  17. Electron temperature fluctuation in the HT-7 tokamak plasma observed by electron cyclotron emission imaging

    International Nuclear Information System (INIS)

    Xiao-Yuan, Xu; Jun, Wang; Yi, Yu; Yi-Zhi, Wen; Chang-Xuan, Yu; Wan-Dong, Liu; Bao-Nian, Wan; Xiang, Gao; Luhmann, N. C.; Domier, C. W.; Wang, Jian; Xia, Z. G.; Shen, Zuowei

    2009-01-01

    The fluctuation of the electron temperature has been measured by using the electron cyclotron emission imaging in the Hefei Tokamak-7 (HT-7) plasma. The electron temperature fluctuation with a broadband spectrum shows that it propagates in the electron diamagnetic drift direction, and the mean poloidal wave-number k-bar θ is calculated to be about 1.58 cm −1 , or k-bar θρ s thickapprox 0.34. It indicates that the fluctuation should come from the electron drift wave turbulence. The linear global scaling of the electron temperature fluctuation with the gradient of electron temperature is consistent with the mixing length scale qualitatively. Evolution of spectrum of the fluctuation during the sawtooth oscillation phases is investigated, and the fluctuation is found to increase with the gradient of electron temperature increasing during most phases of the sawtooth oscillation. The results indicate that the electron temperature gradient is probably the driver of the fluctuation enhancement. The steady heat flux driven by electron temperature fluctuation is estimated and compared with the results from power balance estimation. (fluids, plasmas and electric discharges)

  18. Modeling of Sheath Ion-Molecule Reactions in Plasma Enhanced Chemical Vapor Deposition of Carbon Nanotubes

    Science.gov (United States)

    Hash, David B.; Govindan, T. R.; Meyyappan, M.

    2004-01-01

    In many plasma simulations, ion-molecule reactions are modeled using ion energy independent reaction rate coefficients that are taken from low temperature selected-ion flow tube experiments. Only exothermic or nearly thermoneutral reactions are considered. This is appropriate for plasma applications such as high-density plasma sources in which sheaths are collisionless and ion temperatures 111 the bulk p!asma do not deviate significantly from the gas temperature. However, for applications at high pressure and large sheath voltages, this assumption does not hold as the sheaths are collisional and ions gain significant energy in the sheaths from Joule heating. Ion temperatures and thus reaction rates vary significantly across the discharge, and endothermic reactions become important in the sheaths. One such application is plasma enhanced chemical vapor deposition of carbon nanotubes in which dc discharges are struck at pressures between 1-20 Torr with applied voltages in the range of 500-700 V. The present work investigates The importance of the inclusion of ion energy dependent ion-molecule reaction rates and the role of collision induced dissociation in generating radicals from the feedstock used in carbon nanotube growth.

  19. Low-temperature graphene synthesis using microwave plasma CVD

    International Nuclear Information System (INIS)

    Yamada, Takatoshi; Kim, Jaeho; Ishihara, Masatou; Hasegawa, Masataka

    2013-01-01

    The graphene chemical vapour deposition (CVD) technique at substrate temperatures around 300 °C by a microwave plasma sustained by surface waves (surface wave plasma chemical vapour deposition, SWP-CVD) is discussed. A low-temperature, large-area and high-deposition-rate CVD process for graphene films was developed. It was found from Raman spectra that the deposited films on copper (Cu) substrates consisted of high-quality graphene flakes. The fabricated graphene transparent conductive electrode showed uniform optical transmittance and sheet resistance, which suggests the possibility of graphene for practical electrical and optoelectronic applications. It is intriguing that graphene was successfully deposited on aluminium (Al) substrates, for which we did not expect the catalytic effect to decompose hydrocarbon and hydrogen molecules. We developed a roll-to-roll SWP-CVD system for continuous graphene film deposition towards industrial mass production. A pair of winder and unwinder systems of Cu film was installed in the plasma CVD apparatus. Uniform Raman spectra were confirmed over the whole width of 297 mm of Cu films. We successfully transferred the deposited graphene onto PET films, and confirmed a transmittance of about 95% and a sheet resistance of less than 7 × 10 5 Ω/sq.

  20. Low-temperature graphene synthesis using microwave plasma CVD

    Science.gov (United States)

    Yamada, Takatoshi; Kim, Jaeho; Ishihara, Masatou; Hasegawa, Masataka

    2013-02-01

    The graphene chemical vapour deposition (CVD) technique at substrate temperatures around 300 °C by a microwave plasma sustained by surface waves (surface wave plasma chemical vapour deposition, SWP-CVD) is discussed. A low-temperature, large-area and high-deposition-rate CVD process for graphene films was developed. It was found from Raman spectra that the deposited films on copper (Cu) substrates consisted of high-quality graphene flakes. The fabricated graphene transparent conductive electrode showed uniform optical transmittance and sheet resistance, which suggests the possibility of graphene for practical electrical and optoelectronic applications. It is intriguing that graphene was successfully deposited on aluminium (Al) substrates, for which we did not expect the catalytic effect to decompose hydrocarbon and hydrogen molecules. We developed a roll-to-roll SWP-CVD system for continuous graphene film deposition towards industrial mass production. A pair of winder and unwinder systems of Cu film was installed in the plasma CVD apparatus. Uniform Raman spectra were confirmed over the whole width of 297 mm of Cu films. We successfully transferred the deposited graphene onto PET films, and confirmed a transmittance of about 95% and a sheet resistance of less than 7 × 105 Ω/sq.

  1. Fly ash particles spheroidization using low temperature plasma energy

    Science.gov (United States)

    Shekhovtsov, V. V.; Volokitin, O. G.; Kondratyuk, A. A.; Vitske, R. E.

    2016-11-01

    The paper presents the investigations on producing spherical particles 65-110 μm in size using the energy of low temperature plasma (LTP). These particles are based on flow ash produced by the thermal power plant in Seversk, Tomsk region, Russia. The obtained spherical particles have no defects and are characterized by a smooth exterior surface. The test bench is designed to produce these particles. With due regard for plasma temperature field distribution, it is shown that the transition of fly ash particles to a state of viscous flow occurs at 20 mm distance from the plasma jet. The X-ray phase analysis is carried out for the both original state of fly ash powders and the particles obtained. This analysis shows that fly ash contains 56.23 wt.% SiO2; 20.61 wt.% Al2O3 and 17.55 wt.% Fe2O3 phases that mostly contribute to the integral (experimental) intensity of the diffraction maximum. The LTP treatment results in a complex redistribution of the amorphous phase amount in the obtained spherical particles, including the reduction of O2Si, phase, increase of O22Al20 and Fe2O3 phases and change in Al, O density of O22Al20 chemical unit cell.

  2. Material for electrodes of low temperature plasma generators

    Science.gov (United States)

    Caplan, Malcolm; Vinogradov, Sergel Evge'evich; Ribin, Valeri Vasil'evich; Shekalov, Valentin Ivanovich; Rutberg, Philip Grigor'evich; Safronov, Alexi Anatol'evich

    2008-12-09

    Material for electrodes of low temperature plasma generators. The material contains a porous metal matrix impregnated with a material emitting electrons. The material uses a mixture of copper and iron powders as a porous metal matrix and a Group IIIB metal component such as Y.sub.2O.sub.3 is used as a material emitting electrons at, for example, the proportion of the components, mass %: iron: 3-30; Y.sub.2O.sub.3:0.05-1; copper: the remainder. Copper provides a high level of heat conduction and electric conductance, iron decreases intensity of copper evaporation in the process of plasma creation providing increased strength and lifetime, Y.sub.2O.sub.3 provides decreasing of electronic work function and stability of arc burning. The material can be used for producing the electrodes of low temperature AC plasma generators used for destruction of liquid organic wastes, medical wastes, and municipal wastes as well as for decontamination of low level radioactive waste, the destruction of chemical weapons, warfare toxic agents, etc.

  3. Shear and bulk viscosity of high-temperature gluon plasma

    Science.gov (United States)

    Zhang, Le; Hou, De-Fu

    2018-05-01

    We calculate the shear viscosity (η) and bulk viscosity (ζ) to entropy density (s) ratios η/s and ζ/s of a gluon plasma system in kinetic theory, including both the elastic {gg}≤ftrightarrow {gg} forward scattering and the inelastic soft gluon bremsstrahlung {gg}≤ftrightarrow {ggg} processes. Due to the suppressed contribution to η and ζ in the {gg}≤ftrightarrow {gg} forward scattering and the effective g≤ftrightarrow {gg} gluon splitting, Arnold, Moore and Yaffe (AMY) and Arnold, Dogan and Moore (ADM) have got the leading order computations for η and ζ in high-temperature QCD matter. In this paper, we calculate the correction to η and ζ in the soft gluon bremsstrahlung {gg}≤ftrightarrow {ggg} process with an analytic method. We find that the contribution of the collision term from the {gg}≤ftrightarrow {ggg} soft gluon bremsstrahlung process is just a small perturbation to the {gg}≤ftrightarrow {gg} scattering process and that the correction is at ∼5% level. Then, we obtain the bulk viscosity of the gluon plasma for the number-changing process. Furthermore, our leading-order result for bulk viscosity is the formula \\zeta \\propto \\tfrac{{α }s2{T}3}{ln}{α }s-1} in high-temperature gluon plasma. Supported by Ministry of Science and Technology of China (MSTC) under the “973” Project (2015CB856904(4)) and National Natural Science Foundation of China (11735007, 11521064)

  4. SPECTROSCOPIC DIAGNOSIS IN ELECTRONIC TEMPERATURE OF PHOTOIONISE PLASMAS

    Directory of Open Access Journals (Sweden)

    A. K. Ferouani

    2015-08-01

    Full Text Available In this work, we are interested in the diagnostics in electronic temperature of a plasma purely photoionized, based on the intensity ration of lines emitted by ions helium-like, which have an atomic number Z relatively small. We considered the three lines corresponding to the transitions starting from the excited levels 1s2l towards the fundamental level 1s2 1S0, like appropriate lines. More precisely, the line of resonance w due to the transition 1s2p 1P1 --- 1s2 1 S0, the line of intercombinaison (x,y 1s2p 3 P2,1 --- 1s2 1 S0  as well as prohibited line z due to the transition 1s2 3 S1 --- 1s2 1 S0. These lines appear clearly in the spectra of astrophysical plasmas. As helium-like ion, we chose two, the oxygen O6+ (Z=8 and neon Ne8+ (Z=10. We carried out calculations of the ration of lines intensity G=(z+x+y/w of O6+ and Ne8+  according to the electronic temperature in the range going from 105 to 107 K. We will see that, like it was shown by Gabriel and Jordan in 1969 [1], this intensity ration can be very sensitive to the temperature electronic and practically independent of the electronic density. Consequently, the ration G can be used to determine in a reliable way the electronic temperature of plasma observed [2].

  5. DIAGNOSTIC SPECTROSCOPIQUE EN TEMPERATURE ELECTRONIQUE DES PLASMAS PHOTOIONISES

    Directory of Open Access Journals (Sweden)

    A. K Ferouani

    2009-12-01

    Full Text Available In this work, we are interested in the diagnostics in electronic temperature of a plasma purely photoionized, based on the intensity ration of lines emitted by ions helium-like, witch have an atomic number Z relatively small. We considered the three lines corresponding to the transitions starting from the excited levels 1s2l towards the fundamental level 1s2 1S0, like appropriate lines. More precisely, the line of resonance w due to the transition 1s2p 1P1 1s2 1 S0, the line of intercombinaison (x,y 1s2p 3 P2,1 1s2 1 S0 as well as prohibited line z due to the transition 1s2 3 S1 1s2 1 S0. These lines appear clearly in the spectra of astrophysical plasmas. As helium-like ion, we chose two, the oxygen O6+ (Z=8 and neon Ne8+ (Z=10. We carried out calculations of the ration of lines intensity G=(zxy/w of O6+ and Ne8+ according to the electronic temperature in the range going from 105 to 107 K. We will see that, like it was shown by Gabriel and Jordan in 1969, this intensity ration can be very sensitive to the temperature electronic and practically independent of the electronic density. Consequently, the ration G can be used to determine in a reliable way the electronic temperature of plasma observed.

  6. Anisotropic temperature relaxation of plasmas in an external magnetic field

    International Nuclear Information System (INIS)

    Hassan, M.H.A.

    1977-01-01

    The magnetized kinetic equation derived in an earlier paper (Hassan and Watson, 1977) is used to study the problem of relaxation of anisotropic electron and ion temperatures in a magnetized plasma. In the case of anisotropic electron temperature relaxation, it is shown that for small anisotropies the exchange of energy within the electrons between the components parallel and perpendicular to the magnetic field direction determine the relaxation rate. For anisotropic ion temperature relaxation it is shown that the essential mechanism for relaxation is provided by energy transfer between ions and electrons, and that the expression for the relaxation rate perpendicular to the magnetic field contains a significant term proportional to ln eta 0 ln (msub(e)/msub(i)) (where eta 0 = Ωsub(e)/ksub(D)Vsub(e perpendicular to)), in addition to the term proportional to the Coulomb logarithm. (author)

  7. ELECTRON ENERGY DECAY IN HELIUM AFTERGLOW PLASMAS AT CRYOGENIC TEMPERATURES

    Energy Technology Data Exchange (ETDEWEB)

    Goldan, P. D.; Cahn, J. H.; Goldstein, L.

    1963-10-15

    Studies of decaying afterglow plasmas in helium were ined near 4 deg K by immersion in a liquid helium bath. By means of a Maser Radiometer System, the electron temperature was followed below 200 deg K. Guided microwave propagation and wave interaction techniques premit determination of election number density and collision frequencies for momentum transfer. Electron temperature decay rates of the order of 150 mu sec/p(mm Hg alpha 4.2 deg K) were found. Since thermal relaxation by elastic collisions should be some two orders of magnitude faster than this, the electrons appear to be in quasiequilibrium with a slowly decaying internal heating source. Correlation of the expected decay rates of singlet metastable helium atoms with the electron temperature decay gives good agreement with the present experiment. (auth)

  8. Using Three-Body Recombination to Extract Electron Temperatures of Ultracold Plasmas

    International Nuclear Information System (INIS)

    Fletcher, R. S.; Zhang, X. L.; Rolston, S. L.

    2007-01-01

    Three-body recombination, an important collisional process in plasmas, increases dramatically at low electron temperatures, with an accepted scaling of T e -9/2 . We measure three-body recombination in an ultracold neutral xenon plasma by detecting recombination-created Rydberg atoms using a microwave-ionization technique. With the accepted theory (expected to be applicable for weakly coupled plasmas) and our measured rates, we extract the plasma temperatures, which are in reasonable agreement with previous measurements early in the plasma lifetime. The resulting electron temperatures indicate that the plasma continues to cool to temperatures below 1 K

  9. Review: Plasma-enhanced chemical vapor deposition of nanocrystalline diamond

    Directory of Open Access Journals (Sweden)

    Katsuyuki Okada

    2007-01-01

    Full Text Available Nanocrystalline diamond films have attracted considerable attention because they have a low coefficient of friction and a low electron emission threshold voltage. In this paper, the author reviews the plasma-enhanced chemical vapor deposition (PE-CVD of nanocrystalline diamond and mainly focuses on the growth of nanocrystalline diamond by low-pressure PE-CVD. Nanocrystalline diamond particles of 200–700 nm diameter have been prepared in a 13.56 MHz low-pressure inductively coupled CH4/CO/H2 plasma. The bonding state of carbon atoms was investigated by ultraviolet-excited Raman spectroscopy. Electron energy loss spectroscopy identified sp2-bonded carbons around the 20–50 nm subgrains of nanocrystalline diamond particles. Plasma diagnostics using a Langmuir probe and the comparison with plasma simulation are also reviewed. The electron energy distribution functions are discussed by considering different inelastic interaction channels between electrons and heavy particles in a molecular CH4/H2 plasma.

  10. Quantum effects on the temperature relaxation in plasmas

    International Nuclear Information System (INIS)

    Sakai, Kazuo; Aono, Osamu.

    1979-03-01

    This work was carried out under the collaborating Research Program at Institute of Plasma Physics, Nagoya University. Further communication about this report is to be sent to the Research Information Center, Institute of Plasma Physics, Nagoya University, Nagoya 464, Japan. The rate of equilibration of difference between the ion and electron temperatures is obtained on the basis of the unified theory, in which the collective and binary interactions are both treated properly. The electrons obey the Fermi distribution of arbitrary degeneracy. The rate decreases owing to the degeneracy. Even in the nondegenerated case, the quantum effect appeares in the argument of the Coulomb logarithm. When the de Broglie wave length of the electron is much longer than the radius of close collision, the results agree with those obtained on the Born approximation. In the opposite limit, the classical theory applies. For other cases, graphical examples are given. (author)

  11. Kinetic theory of two-temperature polyatomic plasmas

    Science.gov (United States)

    Orlac'h, Jean-Maxime; Giovangigli, Vincent; Novikova, Tatiana; Roca i Cabarrocas, Pere

    2018-03-01

    We investigate the kinetic theory of two-temperature plasmas for reactive polyatomic gas mixtures. The Knudsen number is taken proportional to the square root of the mass ratio between electrons and heavy-species, and thermal non-equilibrium between electrons and heavy species is allowed. The kinetic non-equilibrium framework also requires a weak coupling between electrons and internal energy modes of heavy species. The zeroth-order and first-order fluid equations are derived by using a generalized Chapman-Enskog method. Expressions for transport fluxes are obtained in terms of macroscopic variable gradients and the corresponding transport coefficients are expressed as bracket products of species perturbed distribution functions. The theory derived in this paper provides a consistent fluid model for non-thermal multicomponent plasmas.

  12. Surface temperature measurement of plasma facing components in tokamaks

    International Nuclear Information System (INIS)

    Amiel, Stephane

    2014-01-01

    During this PhD, the challenges on the non-intrusive surface temperature measurements of metallic plasma facing components in tokamaks are reported. Indeed, a precise material emissivity value is needed for classical infrared methods and the environment contribution has to be known particularly for low emissivities materials. Although methods have been developed to overcome these issues, they have been implemented solely for dedicated experiments. In any case, none of these methods are suitable for surface temperature measurement in tokamaks.The active pyrometry introduced in this study allows surface temperature measurements independently of reflected flux and emissivities using pulsed and modulated photothermal effect. This method has been validated in laboratory on metallic materials with reflected fluxes for pulsed and modulated modes. This experimental validation is coupled with a surface temperature variation induced by photothermal effect and temporal signal evolvement modelling in order to optimize both the heating source characteristics and the data acquisition and treatment. The experimental results have been used to determine the application range in temperature and detection wavelengths. In this context, the design of an active pyrometry system on tokamak has been completed, based on a bicolor camera for a thermography application in metallic (or low emissivity) environment.The active pyrometry method introduced in this study is a complementary technique of classical infrared methods used for thermography in tokamak environment which allows performing local and 2D surface temperature measurements independently of reflected fluxes and emissivities. (author) [fr

  13. Growth and characterization of titanium oxide by plasma enhanced atomic layer deposition

    KAUST Repository

    Zhao, Chao

    2013-09-01

    The growth of TiO2 films by plasma enhanced atomic layer deposition using Star-Ti as a precursor has been systematically studied. The conversion from amorphous to crystalline TiO2 was observed either during high temperature growth or annealing process of the films. The refractive index and bandgap of TiO2 films changed with the growth and annealing temperatures. The optimization of the annealing conditions for TiO2 films was also done by morphology and density studies. © 2013 Elsevier B.V. All rights reserved.

  14. Helical temperature perturbations associated with tearing modes in tokamak plasmas

    International Nuclear Information System (INIS)

    Fitzpatrick, R.

    1994-06-01

    An investigation is made into the electron temperature perturbations associated with tearing modes in tokamak plasmas, with a view to determining the mode structure using Electron Cyclotron Emission (ECE) data. It is found that there is a critical magnetic island width below which the conventional picture where the temperature is flattened inside the separatrix is invalid. This effect comes about because of the stagnation of magnetic field lines in the vicinity of the rational surface and the finite parallel thermal conductivity of the plasma. For islands whose widths lie below the critical value there is no flattening of the electron temperature inside the separatrix. Such islands have quite different ECE signatures to conventional magnetic islands. In fact the two island types could, in principle, be differentiated experimentally. It should also be possible to map out the outer ideal magnetohydrodynamical eigenfunctions using ECE data. Islands whose widths are much less than the critical value are not destabilized by the perturbed bootstrap current, unlike conventional magnetic islands. This effect is found to have a number of very interesting consequences and may, indeed, provide an explanation for some puzzling experimental results regarding error field induced magnetic reconnection. All islands whose widths are much greater than the critical width possess a boundary layer on the separatrix which enables heat to be transported from one side of the island to the other via the X-point region. The structure of this boundary layer is described in some detail. Finally, the critical island width is found to be fairly substantial in conventional tokamak plasmas, provided that the long mean free path nature of parallel heat transport and the anomalous nature of perpendicular heat transport are taken into account in the calculation

  15. Substrate Effect on Plasma Clean Efficiency in Plasma Enhanced Chemical Vapor Deposition System

    Directory of Open Access Journals (Sweden)

    Shiu-Ko JangJian

    2007-01-01

    Full Text Available The plasma clean in a plasma-enhanced chemical vapor deposition (PECVD system plays an important role to ensure the same chamber condition after numerous film depositions. The periodic and applicable plasma clean in deposition chamber also increases wafer yield due to less defect produced during the deposition process. In this study, the plasma clean rate (PCR of silicon oxide is investigated after the silicon nitride deposited on Cu and silicon oxide substrates by remote plasma system (RPS, respectively. The experimental results show that the PCR drastically decreases with Cu substrate compared to that with silicon oxide substrate after numerous silicon nitride depositions. To understand the substrate effect on PCR, the surface element analysis and bonding configuration are executed by X-ray photoelectron spectroscopy (XPS. The high resolution inductively coupled plasma mass spectrometer (HR-ICP-MS is used to analyze microelement of metal ions on the surface of shower head in the PECVD chamber. According to Cu substrate, the results show that micro Cu ion and the CuOx bonding can be detected on the surface of shower head. The Cu ion contamination might grab the fluorine radicals produced by NF3 ddissociation in the RPS and that induces the drastic decrease on PCR.

  16. Low temperature spark plasma sintering of YIG powders

    International Nuclear Information System (INIS)

    Fernandez-Garcia, L.; Suarez, M.; Menendez, J.L.

    2010-01-01

    A transition from a low to a high spin state in the magnetization saturation between 1000 and 1100 o C calcination temperature is observed in YIG powders prepared by oxides mixture. Spark plasma sintering of these powders between 900 and 950 o C leads to dense samples with minimal formation of YFeO 3 , opening the way to co-sintering of YIG with metals or metallic alloys. The optical properties depend on the sintering stage: low (high) density samples show poor (bulk) optical absorption.

  17. The Fungal Spores Survival Under the Low-Temperature Plasma

    Science.gov (United States)

    Soušková, Hana; Scholtz, V.; Julák, J.; Savická, D.

    This paper presents an experimental apparatus for the decontamination and sterilization of water suspension of fungal spores. The fungicidal effect of stabilized positive and negative corona discharges on four fungal species Aspergillus oryzae, Clacosporium sphaerospermum, Penicillium crustosum and Alternaria sp. was studied. Simultaneously, the slower growing of exposed fungal spores was observed. The obtained results are substantially different in comparison with those of the analogous experiments performed with bacteria. It may be concluded that fungi are more resistant to the low-temperature plasma.

  18. Plasma-enhanced atomic-layer-deposited MoO{sub x} emitters for silicon heterojunction solar cells

    Energy Technology Data Exchange (ETDEWEB)

    Ziegler, Johannes; Schneider, Thomas; Sprafke, Alexander N. [Martin-Luther-University Halle-Wittenberg, mu-MD Group, Institute of Physics, Halle (Germany); Mews, Mathias; Korte, Lars [Helmholtz-Zentrum Berlin fuer Materialien und Energie GmbH, Institute for Silicon-Photovoltaics, Berlin (Germany); Kaufmann, Kai [Fraunhofer Center for Silicon Photovoltaics CSP, Halle (Germany); University of Applied Sciences, Hochschule Anhalt Koethen, Koethen (Germany); Wehrspohn, Ralf B. [Martin-Luther-University Halle-Wittenberg, mu-MD Group, Institute of Physics, Halle (Germany); Fraunhofer Institute for Mechanics of Materials IWM Halle, Halle (Germany)

    2015-09-15

    A method for the deposition of molybdenum oxide (MoO{sub x}) with high growth rates at temperatures below 200 C based on plasma-enhanced atomic layer deposition is presented. The stoichiometry of the over-stoichiometric MoO{sub x} films can be adjusted by the plasma parameters. First results of these layers acting as hole-selective contacts in silicon heterojunction solar cells are presented and discussed. (orig.)

  19. Experimental setup for producing tungsten coated graphite tiles using plasma enhanced chemical vapor deposition technique for fusion plasma applications

    International Nuclear Information System (INIS)

    Chauhan, Sachin Singh; Sharma, Uttam; Choudhary, K.K.; Sanyasi, A.K.; Ghosh, J.; Sharma, Jayshree

    2013-01-01

    Plasma wall interaction (PWI) in fusion grade machines puts stringent demands on the choice of materials in terms of high heat load handling capabilities and low sputtering yields. Choice of suitable material still remains a challenge and open topic of research for the PWI community. Carbon fibre composites (CFC), Beryllium (Be), and Tungsten (W) are now being considered as first runners for the first wall components of future fusion machines. Tungsten is considered to be one of the suitable materials for the job because of its superior properties than carbon like low physical sputtering yield and high sputter energy threshold, high melting point, fairly high re-crystallization temperature, low fuel retention capabilities, low chemical sputtering with hydrogen and its isotopes and most importantly the reparability with various plasma techniques both ex-situ and in-situ. Plasma assisted chemical vapour deposition is considered among various techniques as the most preferable technique for fabricating tungsten coated graphite tiles to be used as tokamak first wall and target components. These coated tiles are more favourable compared to pure tungsten due to their light weight and easier machining. A system has been designed, fabricated and installed at SVITS, Indore for producing tungsten coated graphite tiles using Plasma Enhanced Chemical Vapor Deposition (PE-CVD) technique for Fusion plasma applications. The system contains a vacuum chamber, a turbo-molecular pump, two electrodes, vacuum gauges, mass analyzer, mass flow controllers and a RF power supply for producing the plasma using hydrogen gas. The graphite tiles will be put on one of the electrodes and WF6 gas will be inserted in a controlled manner in the hydrogen plasma to achieve the tungsten-coating with WF6 dissociation. The system is integrated at SVITS, Indore and a vacuum of the order of 3*10 -6 is achieved and glow discharge plasma has been created to test all the sub-systems. The system design with

  20. Enhanced battery model including temperature effects

    NARCIS (Netherlands)

    Rosca, B.; Wilkins, S.

    2013-01-01

    Within electric and hybrid vehicles, batteries are used to provide/buffer the energy required for driving. However, battery performance varies throughout the temperature range specific to automotive applications, and as such, models that describe this behaviour are required. This paper presents a

  1. Flare plasma density determination using observed temperature profiles

    International Nuclear Information System (INIS)

    Garcia, H.A.

    1986-01-01

    Observed electron temperature variations derived from flux intensity ratios of whole-disk continuum soft X-ray spectra recorded by GOES satellites are presently subjected to an analysis that is based on the nonequilibrium energy balance equation in order to obtain the physical properties of a large solar flare from onset through the gradual phase. A self-similar formalism which reduces the nonlinear, second-order PDE in length and time to a more tractable, nonlinear, first-order Ricatti equation is invoked. Plasma density is the principal unknown variable contained in the Ricatti equation, which also contains first-order time derivatives and first- and second-order spatial derivatives of temperature. This methodology is presently applied to the moderate size flare of January 28, 1982, for which a density profile is deduced under various parametric conditions. 37 references

  2. Collisional drift waves in a plasma with electron temperature inhomogeneity

    International Nuclear Information System (INIS)

    Drake, J.F.; Hassam, A.B.

    1981-01-01

    A fluid theory of collisional electrostatic drift waves in a plasma slab with magnetic shear is presented. Both electron temperature and density gradients are included. The equations are solved analytically in all relevant regions of the parameter space defined by the magnetic shear strength and the perpendicular wavelength and explicit expressions for the growth rates are given. For shear strengths appropriate for present-day tokamak discharges the temperature gradient produces potential wells which localize the mode in the electron resistive region, well inside the ion sound turning points. Mode stability arises from a competition between the destabilizing influence of the time dependent thermal force and the stabilizing influence of electron energy dissipation. Convective energy loss is not important for shear parameters of present-day fusion devices

  3. Enhanced photoluminescence from porous silicon by hydrogen-plasma etching

    International Nuclear Information System (INIS)

    Wang, Q.; Gu, C.Z.; Li, J.J.; Wang, Z.L.; Shi, C.Y.; Xu, P.; Zhu, K.; Liu, Y.L.

    2005-01-01

    Porous silicon (PS) was etched by hydrogen plasma. On the surface a large number of silicon nanocone arrays and nanocrystallites were formed. It is found that the photoluminescence of the H-etched porous silicon is highly enhanced. Correspondingly, three emission centers including red, green, and blue emissions are shown to contribute to the enhanced photoluminescence of the H-etched PS, which originate from the recombination of trapped electrons with free holes due to Si=O bonding at the surface of the silicon nanocrystallites, the quantum size confinement effect, and oxygen vacancy in the surface SiO 2 layer, respectively. In particular, the increase of SiO x (x<2) formed on the surface of the H-etched porous silicon plays a very important role in enhancing the photoluminescence properties

  4. Enhanced Temperature Control Method Using ANFIS with FPGA

    Directory of Open Access Journals (Sweden)

    Chiung-Wei Huang

    2014-01-01

    Full Text Available Temperature control in etching process is important for semiconductor manufacturing technology. However, pressure variations in vacuum chamber results in a change in temperature, worsening the accuracy of the temperature of the wafer and the speed and quality of the etching process. This work develops an adaptive network-based fuzzy inference system (ANFIS using a field-programmable gate array (FPGA to improve the effectiveness. The proposed method adjusts every membership function to keep the temperature in the chamber stable. The improvement of the proposed algorithm is confirmed using a medium vacuum (MV inductively-coupled plasma- (ICP- type etcher.

  5. Investigation of the connection between plasma temperature and electrode temperature in metal-halide lamps

    International Nuclear Information System (INIS)

    Fromm, D.C.; Gleixner, K.H.; Lieder, G.H.

    2002-01-01

    Spatial profiles of electrode temperatures and plasma temperatures have been measured on 'real' HID lamps filled with a commercial metal-halide compound. The absolute accuracy of pyrometric determination of electrode tip temperatures was ±30 K, while the determination of plasma core temperatures, using a modified Bartels method, has an accuracy of ±100 K. We could deduce a close correlation between the plasma temperature in front of an electrode T p and its tip temperature T t due to the influence of the cataphoresis. If T p is reduced at the cathode the T t value has also lowered, whereas T p at the anode is raised together with its T t data. This correlation disappears at ballast frequencies above 100 Hz, whereas the cataphoresis influence on T p continues up to 500 Hz. Based on the latter limit, a rough estimation of the cataphoresis velocity delivers 700 cm s -1 . As a tentative interpretation, we suggest that the connection between T p and T t is caused by an increase of the ion part of the total current at the cathode due to Na accumulation before it. Thus, the cathode has to emit fewer electrons and works at a lower temperature. Further results are the temporal behaviour of T t depends on the ballast type. For vertical operation the strong influence of convection on T t has also to be taken into account. Above 100 Hz, where only convection plays a role, the upper electrode T t exceeds the T t value of the lower electrode by nearly 400 K. This discrepancy one may explain, tentatively, by convection heating of the upper electrode and convection cooling of the lower one. (author)

  6. Modeling of magnetically enhanced capacitively coupled plasma sources: Ar discharges

    International Nuclear Information System (INIS)

    Kushner, Mark J.

    2003-01-01

    Magnetically enhanced capacitively coupled plasma sources use transverse static magnetic fields to modify the performance of low pressure radio frequency discharges. Magnetically enhanced reactive ion etching (MERIE) sources typically use magnetic fields of tens to hundreds of Gauss parallel to the substrate to increase the plasma density at a given pressure or to lower the operating pressure. In this article results from a two-dimensional hybrid-fluid computational investigation of MERIE reactors with plasmas sustained in argon are discussed for an industrially relevant geometry. The reduction in electron cross field mobility as the magnetic field increases produces a systematic decrease in the dc bias (becoming more positive). This decrease is accompanied by a decrease in the energy and increase in angular spread of the ion flux to the substrate. Similar trends are observed when decreasing pressure for a constant magnetic field. Although for constant power the magnitudes of ion fluxes to the substrate increase with moderate magnetic fields, the fluxes decreased at larger magnetic fields. These trends are due, in part, to a reduction in the contributions of more efficient multistep ionization

  7. Electrostatic fluctuations measured in low temperature helical plasmas with low collisionality

    International Nuclear Information System (INIS)

    Takeuchi, M.; Ikeda, R.; Ito, T.; Toi, K.; Suzuki, C.; Matsunaga, G.

    2004-01-01

    Electrostatic fluctuations have been measured by Langmuir probes from edge to core plasma region in low temperature helical plasmas which are produced by 2.45 GHz microwaves at very low field less than 0.1 T. The principal dimensionless parameters of the plasmas, that is, the normalized electron-ion collision frequency ν ei , and averaged plasma β φ and others are in the same range of them in high temperature plasmas, except the normalized gyro radius ρ s . The data on fluctuation characteristics from the dimensionally similar low temperature plasmas may give an important insight into the understanding of turbulent transport in high temperature plasmas. Dependences of fluctuation amplitudes on the radial electric field shear, ρ s and ν ei are investigated. Electrostatic fluctuations propagating in electron-diamagnetic drift direction have been observed in the plasma edge region and in ion-diamagnetic drift direction in the plasma core region. (authors)

  8. UV excimer laser and low temperature plasma treatments of polyamide materials

    Science.gov (United States)

    Yip, Yiu Wan Joanne

    ) functional groups, which increased water absorption. However, after tetrafluoromethane plasma treatment it was found that the -CF, -CF2 and -CF3 groups were introduced to the polyamide surface and this enhanced the hydrophobicity of the fabric. Suggested explanations are given of the mechanisms that produce the structure of the polyamide after the processes of laser irradiation (both high- and low-fluence) and plasma treatment. The fundamental approach used in modelling was considered the temperature profile of the material during the treatment. The development of high-fluence induced structures was caused by elevated temperatures in the subsurface volume and preexisting stress caused by fiber extrusion. The structure formation under LF laser irradiation was determined by thermal effect accompanied by the optical phenomenon of interference. Ripple structures formed by plasma were closely related to physical or chemical etching. Possible applications of plasma and laser technologies in the textile and clothing industries are considered. Oxygen plasma seems to be the best candidate to improve the wettability of the fabric, while tetrafluoromethane plasma can be applied to produce a water repellent surface. Surface treatments including CF4 plasma, high-fluence and low-fluence laser treatments produce a deeper color in disperse dyed fabrics using the same amount of dyestuff as chemicals like leveling agents and dyestuff can be reduced during the textile manufacturing process. UV laser and low temperature plasma modification processes are promising techniques for polymer/fabric surface modification and have industrial potential as they are environmentally friendly dry processes which do not involve any solvents.

  9. Plasma-enhanced chemical vapor deposition for YBCO film fabrication of superconducting fault-current limiter

    Energy Technology Data Exchange (ETDEWEB)

    Jun, Byung Hyuk; Kim, Chan Joong

    2006-05-15

    Since the high-temperature superconductor of oxide type was founded, many researches and efforts have been performed for finding its application field. The YBCO superconducting film fabricated on economic metal substrate with uniform critical current density is considered as superconducting fault-current limiter (SFCL). There are physical and chemical processes to fabricate superconductor film, and it is understood that the chemical methods are more economic to deposit large area. Among them, chemical vapor deposition (CVD) is a promising deposition method in obtaining film uniformity. To solve the problems due to the high deposition temperature of thermal CVD, plasma-enhanced chemical vapor deposition (PECVD) is suggested. This report describes the principle and fabrication trend of SFCL, example of YBCO film deposition by PECVD method, and principle of plasma deposition.

  10. Low Temperature Plasma for decontamination of E. coli in milk.

    Science.gov (United States)

    Gurol, C; Ekinci, F Y; Aslan, N; Korachi, M

    2012-06-15

    Raw milk is a natural, highly nutritious product and a quick and easy supplement for human dietary requirements. Elimination of bacteria in milk has been a problem for decades and new methods with regards to non-thermal applications which do not harm the chemical composition of milk, are currently under investigation. The objective of the study was to determine the potential use of a novel, Low Temperature Plasma (LTP) system for its capability of killing Escherichia coli in milk with different fat contents. The time dependent effect of atmospheric corona discharge generated with 9kV of AC power supply on E. coli ATCC 25922 dispersed in whole, semi skimmed and skimmed milk was examined. Plasma was applied at time intervals of 0, 3, 6, 9, 12, 15 and 20min. A significant 54% reduction in the population of E. coli cells after only 3min was observed regardless of the fat content of the milk. The initial pre-plasma bacterial count of 7.78 Log CFU/ml in whole milk was decreased to 3.63 Log CFU/ml after 20min of plasma application. LTP did not cause any significant change to the pH and color values of raw milk samples. No viable cells were detected after one week examination in whole milk samples and remained so over the 6week storage period. The findings of this study show that the novel LTP system tested was able to significantly reduce E. coli in milk by more than a 3 fold log reduction without significantly affecting pH or color properties. Copyright © 2012 Elsevier B.V. All rights reserved.

  11. Enhancement and stabilization of plasma using collinear long-short double-pulse laser-induced breakdown spectroscopy

    Science.gov (United States)

    Cui, Minchao; Deguchi, Yoshihiro; Wang, Zhenzhen; Fujita, Yuki; Liu, Renwei; Shiou, Fang-Jung; Zhao, Shengdun

    2018-04-01

    A collinear long-short dual-pulse laser-induced breakdown spectroscopy (DP-LIBS) method was employed to enhance and stabilize the laser-induced plasma from steel sample. The long-pulse-width laser beam with the pulse width of 60 μs was generated by a Nd: YAG laser which was operated at FR (free running) mode. The comparative experiments were carried out between single pulse LIBS (SP-LIBS) and long-short DP-LIBS. The recorded results showed that the emission intensities and the temperature of plasma were enhanced by long-short DP-LIBS. The plasma images showed that the plasma was bigger and had a longer lifetime in long-short DP-LIBS situation. Through the calculation of time-resolved plasma temperature and intensity ratio, it can be concluded that the plasma was stabilized by the long-pulse-width laser beam. The long-short DP-LIBS method also generated the stable plasma condition from the samples with different initial temperatures, which overcame the difficulties of LIBS in the online measurement for steel production line.

  12. Enhanced temperature-independent magnetoresistance below the ...

    Indian Academy of Sciences (India)

    tions in the magnetic recording industry [1–3]. The GMR effects considerably larger than those in ... 0.0. 0.5. 1.0. 1.5. 2.0. 2.5. 3.0. 3.5. 4.0. Resistance (M. Ω. ) Figure 1. Temperature dependence of resistance at 0 Oe, 20 kOe and 40 kOe of. LNCMO film. 1090. Pramana – J. Phys., Vol. 58, Nos 5 & 6, May & June 2002 ...

  13. Ground temperature enhancements in seismic regions

    Science.gov (United States)

    Parrot, M.; Pokhotelov, O.; Surkov, V.; Hayakawa, M.

    In the past decade, numerous observations of surface and near surface temperature anomalies before earthquakes have been published. Monitoring of the seismo -active regions from space have been made in visible and infrared ranges by various satellites: NOOA satellites, UARS, TERRA and etc. This paper presents some examples of these observations. A review of different mechanisms to explain the phenomenon is given and a more detailed explanation of the mechanism proposed by the authors is presented. It is shown that long term temperature anomalies can arise due to the rock warming resulting from the underground water upward filtrating. However, the short term temperature anomalies observed several days before an earthquake, are due to the change in the specific heat capacity and in the heat conductivity of the soil induced by the variations of the moisture. This research is partially supported by the Commission of the EU (Grant No. INTAS-2001-0456), by ISTC through Research Grant No. 1121 and by Russian Fund for Basic Research through Grant No. 02-05-64612.

  14. Plasma Enhanced Chemical Vapour Deposition of Horizontally Aligned Carbon Nanotubes

    Directory of Open Access Journals (Sweden)

    Matthew T. Cole

    2013-05-01

    Full Text Available A plasma-enhanced chemical vapour deposition reactor has been developed to synthesis horizontally aligned carbon nanotubes. The width of the aligning sheath was modelled based on a collisionless, quasi-neutral, Child’s law ion sheath where these estimates were empirically validated by direct Langmuir probe measurements, thereby confirming the proposed reactors ability to extend the existing sheath fields by up to 7 mm. A 7 mbar growth atmosphere combined with a 25 W plasma permitted the concurrent growth and alignment of carbon nanotubes with electric fields of the order of 0.04 V μm−1 with linear packing densities of up to ~5 × 104 cm−1. These results open up the potential for multi-directional in situ alignment of carbon nanotubes providing one viable route to the fabrication of many novel optoelectronic devices.

  15. Elastic scattering and transport coefficients for a quark plasma in SUf(3) at finite temperatures

    Science.gov (United States)

    Rehberg, P.; Klevansky, S. P.; Hüfner, J.

    1996-02-01

    The temperature dependence of the elastic-scattering processes qq' → qq' and q overlineq' → q overlineq' , with q, q' = u, d, s is studied as a function of the scattering angle and the center-of-mass energy of the collision within the framework of the SUf(3) Nambu-Jona-Lasinio model. Critical scattering at threshold is observed in the q overlineq' → q overlineq' process, leading to an enhancement of the cross section as occurs in the phenomenon of critical opalescence. Transport properties such as viscosity, mean free paths and thermal relaxation times are calculated. Strangeness enhancement is investigated via the chemical relaxation times, which are found to be considerably higher than those calculated via perturbative QCD. A comparison with the experimental values for the strangeness enhancement in S + S collisions leads to an upper limit of 4 fm/ c for the lifetime of the plasma.

  16. Ion temperature anisotropy limitation in high beta plasmas

    International Nuclear Information System (INIS)

    Scime, Earl E.; Keiter, Paul A.; Balkey, Matthew M.; Boivin, Robert F.; Kline, John L.; Blackburn, Melanie; Gary, S. Peter

    2000-01-01

    Measurements of parallel and perpendicular ion temperatures in the Large Experiment on Instabilities and Anisotropies (LEIA) space simulation chamber display an inverse correlation between the upper bound on the ion temperature anisotropy and the parallel ion beta (β=8πnkT/B 2 ). Fluctuation measurements indicate the presence of low frequency, transverse, electromagnetic waves with wave numbers and frequencies that are consistent with predictions for Alfven Ion Cyclotron instabilities. These observations are also consistent with in situ spacecraft measurements in the Earth's magnetosheath and with a theoretical/computational model that predicts that such an upper bound on the ion temperature anisotropy is imposed by scattering from enhanced fluctuations due to growth of the Alfven ion cyclotron instability. (c) 2000 American Institute of Physics

  17. Quasilinear dynamics of a cloud of hot electrons propagating through a plasma with decreasing density and temperature

    International Nuclear Information System (INIS)

    Foroutan, G.; Khalilpour, H.; Moslehi-Fard, M.; Li, B.; Robinson, P. A.

    2008-01-01

    The effects of plasma inhomogeneities on the propagation of a cloud of hot electrons through a cold background plasma and generation of Langmuir waves are investigated using numerical simulations of the quasilinear equations. It is found that in a plasma with decreasing density the quasilinear relaxation of the electron distribution in velocity space is accelerated and the levels of the generated Langmuir waves are enhanced. The magnitude of the induced emission rate is increased and its maximum value moves to lower velocities. Due to density gradient the height of plateau shows an increase at small distances and a corresponding decrease at large distances. It is also found that in a plasma with decreasing temperature, the relaxation of the beam is retarded, the spectral density of Langmuir waves is broadened, and the height of the plateau decreases below its value in a uniform plasma. In the presence of both density and temperature gradients, at given position, the height and upper boundary of the plateau and the level of Langmuir waves are all increased at small velocities. The spatial expansion of the beam is increased by the plasma inhomogeneities, but its average velocity of propagation decreases. Initially, at a given position, the velocity at the upper boundary of the plateau is smaller in the presence of the density gradient than in the uniform plasma but the reverse is true at longer times. Due to temperature gradient, at large times and small distances, the upper boundary of the plateau is increased above its value in the uniform plasma. Because of fast relaxation, the value of the lower boundary of the plateau in the plasma with decreasing density is always less than its value in the uniform plasma. It is found that the local velocity of the beam decreases when the density gradient is present. The local velocity spread of the beam remains unchanged during the propagation of the beam in the uniform plasma, but increases in the presence of inhomogeneities.

  18. Plasma-enhanced chemical vapor deposited silicon oxynitride films for optical waveguide bridges for use in mechanical sensors

    DEFF Research Database (Denmark)

    Storgaard-Larsen, Torben; Leistiko, Otto

    1997-01-01

    In this paper the influence of RF power, ammonia flow, annealing temperature, and annealing time on the optical and mechanical properties of plasma-enhanced chemically vapor deposited silicon oxynitride films, is presented. A low refractive index (1.47 to 1.48) film having tensile stress has been...

  19. Low temperature synthesis of ternary metal phosphides using plasma for asymmetric supercapacitors

    KAUST Repository

    Liang, Hanfeng; Xia, Chuan; Jiang, Qiu; Gandi, Appala; Schwingenschlö gl, Udo; Alshareef, Husam N.

    2017-01-01

    We report a versatile route for the preparation of metal phosphides using PH plasma for supercapacitor applications. The high reactivity of plasma allows rapid and low temperature conversion of hydroxides into monometallic, bimetallic, or even more

  20. Development of plasma bolometers using fiber-optic temperature sensors

    Energy Technology Data Exchange (ETDEWEB)

    Reinke, M. L., E-mail: reinkeml@ornl.gov [Oak Ridge National Laboratory, Oak Ridge, Tennessee 37831 (United States); Han, M.; Liu, G. [University of Nebraska-Lincoln, Lincoln, Nebraska 68588 (United States); Eden, G. G. van [Dutch Institute for Fundamental Energy Research, De Zaale 20, 5612 AJ Eindhoven (Netherlands); Evenblij, R.; Haverdings, M. [Technobis, Pyrietstraat 2, 1812 SC Alkmaar (Netherlands); Stratton, B. C. [Princeton Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543 (United States)

    2016-11-15

    Measurements of radiated power in magnetically confined plasmas are important for exhaust studies in present experiments and expected to be a critical diagnostic for future fusion reactors. Resistive bolometer sensors have long been utilized in tokamaks and helical devices but suffer from electromagnetic interference (EMI). Results are shown from initial testing of a new bolometer concept based on fiber-optic temperature sensor technology. A small, 80 μm diameter, 200 μm long silicon pillar attached to the end of a single mode fiber-optic cable acts as a Fabry–Pérot cavity when broadband light, λ{sub o} ∼ 1550 nm, is transmitted along the fiber. Changes in temperature alter the optical path length of the cavity primarily through the thermo-optic effect, resulting in a shift of fringes reflected from the pillar detected using an I-MON 512 OEM spectrometer. While initially designed for use in liquids, this sensor has ideal properties for use as a plasma bolometer: a time constant, in air, of ∼150 ms, strong absorption in the spectral range of plasma emission, immunity to local EMI, and the ability to measure changes in temperature remotely. Its compact design offers unique opportunities for integration into the vacuum environment in places unsuitable for a resistive bolometer. Using a variable focus 5 mW, 405 nm, modulating laser, the signal to noise ratio versus power density of various bolometer technologies are directly compared, estimating the noise equivalent power density (NEPD). Present tests show the fiber-optic bolometer to have NEPD of 5-10 W/m{sup 2} when compared to those of the resistive bolometer which can achieve <0.5 W/m{sup 2} in the laboratory, but this can degrade to 1-2 W/m{sup 2} or worse when installed on a tokamak. Concepts are discussed to improve the signal to noise ratio of this new fiber-optic bolometer by reducing the pillar height and adding thin metallic coatings, along with improving the spectral resolution of the interrogator.

  1. Graphene Synthesis by Plasma-Enhanced CVD Growth with Ethanol

    OpenAIRE

    Campo, T.; Cotto, M.; Márquez, F.; Elizalde, E.; Morant, C.

    2016-01-01

    A modified route to synthesize graphene flakes is proposed using the Chemical Vapor Deposition (CVD) technique, by using copper substrates as supports. The carbon source used was ethanol, the synthesis temperature was 950°C and the pressure was controlled along the whole process. In this CVD synthesis process the incorporation of the carbon source was produced at low pressure and 950°C inducing the appearance of a plasma blue flash inside the quartz tube. Apparently, the presence of this plas...

  2. Transport analysis of pellet-enhanced ICRH plasma in JET

    International Nuclear Information System (INIS)

    Hammett, G.W.; Colestock, P.L.; Granetz, R.S.; McCune, D.C.; Phillips, C.K.; Schmidt, G.L.; Smithe, D.N.; Kupschus, P.

    1989-01-01

    Performance of JET ICRH heated discharges has been significantly enhanced by using pellet fueling to produce a peaked density target for ICRH. The central T i is observed to increase by up to 80%, central T e by up to 40%, and the neutron rate by up to 400%, over their no-pellet values (which are already in the enhanced 'monster-sawtooth' regime). In this paper we describe the transport analysis of these discharges using the TRANSP code. These results indicate that the thermal diffusivities χ i and χ e are reduced by a factor of ∼2 near the plasma center where the pellets have increased the density gradient. The paper focuses on JET discharge 16211 which is documented more fully in a companion paper. (author) 6 refs., 8 figs

  3. Feasibility Studies of the Two Filters Method in TJ-II for Electron Temperature Measurements in High Density Plasmas

    International Nuclear Information System (INIS)

    Baiao, D.; Medina, F.; Ochando, M.; Varandas, C.

    2009-01-01

    The TJ-II plasma soft X-ray emission was studied in order to establish an adequate setup for an electron temperature diagnostic suitable for high density, with spatial and temporal resolutions, based on the two-filters method. The preliminary experimental results reported were obtained with two diagnostics (an X-ray PHA based on a Ge detector and a tomography system) already installed in TJ-II stellarator. These results lead to the conclusion that the two-filters method was a suitable option for an electron temperature diagnostic for high-density plasmas in TJ-II. We present the design and fi rst results obtained with a prototype for the measurement of electron temperature in TJ-II plasmas heated with energetic neutral beams. This system consists in two AXUV20A detectors which measure the soft X-ray plasma emissivity trough beryllium filters of different thickness. From the two-filters technique it is possible to estimate the electron temperature. The analyses carried out allowed concluding which filter thicknesses are most suited for TJ-II plasmas, and enhanced the need of a computer code to simulate signals and plasma compositions. (Author) 7 refs.

  4. Feasibility Studies of the Two Filters Method in TJ-II for Electron Temperature Measurements in High Density Plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Baiao, D.; Medina, F.; Ochando, M.; Varandas, C.

    2009-07-01

    The TJ-II plasma soft X-ray emission was studied in order to establish an adequate setup for an electron temperature diagnostic suitable for high density, with spatial and temporal resolutions, based on the two-filters method. The preliminary experimental results reported were obtained with two diagnostics (an X-ray PHA based on a Ge detector and a tomography system) already installed in TJ-II stellarator. These results lead to the conclusion that the two-filters method was a suitable option for an electron temperature diagnostic for high-density plasmas in TJ-II. We present the design and fi rst results obtained with a prototype for the measurement of electron temperature in TJ-II plasmas heated with energetic neutral beams. This system consists in two AXUV20A detectors which measure the soft X-ray plasma emissivity trough beryllium filters of different thickness. From the two-filters technique it is possible to estimate the electron temperature. The analyses carried out allowed concluding which filter thicknesses are most suited for TJ-II plasmas, and enhanced the need of a computer code to simulate signals and plasma compositions. (Author) 7 refs.

  5. A special cell morphology of saccharomyces cerevisiae induced by low-temperature plasma

    International Nuclear Information System (INIS)

    Ling Dajun; Cao Jinxiang

    2003-01-01

    A special cell morphology, cavity-like cells, was found in posterities of Saccharomyces cerevisiae treated by low-temperature air plasma with different powers. The feature of the special morphology indicates that the cavity-like cells may be formed by cellular mutation effect induced by the plasma, instead of direct cellular damage by the plasma. The results suggest that the cellular mutation effect of the low-temperature plasma is a complex process

  6. Solitary Langmuir waves in two-electron temperature plasma

    Science.gov (United States)

    Prudkikh, V. V.; Prudkikh

    2014-06-01

    Nonlinear interaction of Langmuir and ion-acoustic waves in two-electron temperature plasma is investigated. New integrable wave interaction regime was discovered, this regime corresponds to the Langmuir soliton with three-hump amplitude, propagating with a speed close to the ion-sound speed in the conditions of strong non-isothermality of electronic components. It was discovered that besides the known analytical solution in the form of one- and two-hump waves, there exists a range of solutions in the form of solitary waves, which in the form of envelope has multi-peak structure and differs from the standard profiles described by hyperbolic functions. In case of fixed plasma parameters, different group velocities correspond to the waves with different number of peaks. It is found that the Langmuir wave package contains both even and uneven numbers of oscillations. Low-frequency potential here has uneven number of peaks. Interrelation of obtained and known earlier results are also discussed.

  7. Electron temperatures of inductively coupled Cl2-Ar plasmas

    International Nuclear Information System (INIS)

    Fuller, N.C.M.; Donnelly, Vincent M.; Herman, Irving P.

    2002-01-01

    Trace rare gases optical emission spectroscopy has been used to measure the electron temperature, T e , in a high-density inductively coupled Cl 2 -Ar plasma at 18 mTorr as function of the 13.56 MHz radio frequency power and Ar fraction. Only the Kr and Xe emission lines were used to determine T e , because of evidence of radiation trapping when the Ar emission lines were also used for larger Ar fractions. At 600 W (10.6 W cm-2), T e increases from ∼4.0±0.5 eV to ∼6.0±2.0 eV as the Ar fraction increases from 1% to 96%. In the H (inductive, bright) mode, T e , for a 'neat' chlorine plasma (including 1% of each He/Ne/Ar/Kr/Xe) increases only slightly from ∼3.8 to 4.0 eV as power increases from 450 to 750 W. This increase is much larger for larger Ar fractions, such as from ∼4.0 to 7.3 eV for 78% Ar. Most of these effects can be understood using the fundamental particle balance equation

  8. Exchange corrections in a low-temperature plasma.

    Science.gov (United States)

    Ekman, Robin; Zamanian, Jens; Brodin, Gert

    2015-07-01

    We have studied the exchange corrections to linear electrostatic wave propagation in a plasma using a quantum kinetic formalism. Specifically, we have considered the zero-temperature limit. In order to simplify the calculations we have focused on the long-wavelength limit, i.e., wavelengths much longer than the de Broglie wavelength. For the case of ion-acoustic waves we have calculated the exchange correction both to the damping rate and the real part of the frequency. For Langmuir waves the frequency shift due to exchange effects is found. Our results are compared with the frequency shifts deduced from commonly used exchange potentials which are computed from density-functional theory.

  9. Investigation of plasma potential and pulsed discharge characteristics in enhanced glow discharge plasma immersion ion implantation and deposition

    International Nuclear Information System (INIS)

    Li Liuhe; Lu Qiuyuan; Fu, Ricky K.Y.; Chu, Paul K.

    2009-01-01

    Enhanced glow discharge plasma immersion ion implantation and deposition (EGD-PII and D) does not require external plasma sources. In this technique, the plasma is produced by self-glow discharge when a high negative voltage is applied to the sample. The small-area, pointed-shape hollow anode and large area tabular cathode form an electron-focused electric field. Using a special electric field design, the electrons from either the plasma or target (secondary electrons) are focused to a special hollow anode. As a result of the special electron-focusing field, the self-glow discharge process can be enhanced to achieve effective ion implantation into the substrate. In this work, the plasma potential distribution is investigated in details and the possible pulse discharge mechanism is discussed. The unique characteristics of the pulsed plasma and plasma extinction are studied.

  10. Application of low-temperature plasma for the synthesis of hydrogenated graphene (graphane)

    Science.gov (United States)

    Shavelkina, M. B.; Amirov, R. H.; Katarzhis, V. A.; Kiselev, V. I.

    2017-12-01

    The possibility of a direct synthesis of hydrogenated graphene in decomposition of methane by means of low-temperature plasma was investigated. A DC plasma torch with an expanding channel-anode, a vortex gas supply and a self-setting arc length was used as a generator of low-temperature plasma. Argon was used as the plasma-forming gas. The temperatures of argon plasma and with methane addition to it were determined on the basis of spectral measurements. The synthesis products were characterized by electron microscopy and thermogravimetry. The effect of hydrogenated graphene as a nanomodifier on the properties of the cubic boron nitride based functional ceramics was investigated.

  11. Properties of plasma sheath with ion temperature in magnetic fusion devices

    International Nuclear Information System (INIS)

    Liu Jinyuan; Wang Feng; Sun Jizhong

    2011-01-01

    The plasma sheath properties in a strong magnetic field are investigated in this work using a steady state two-fluid model. The motion of ions is affected heavily by the strong magnetic field in fusion devices; meanwhile, the effect of ion temperature cannot be neglected for the plasma in such devices. A criterion for the plasma sheath in a strong magnetic field, which differs from the well-known Bohm criterion for low temperature plasma sheath, is established theoretically with a fluid model. The fluid model is then solved numerically to obtain detailed sheath information under different ion temperatures, plasma densities, and magnetic field strengths.

  12. Thermal and nonthermal electron cyclotron emission by high-temperature tokamak plasmas

    International Nuclear Information System (INIS)

    Airoldi, A.; Ramponi, G.

    1997-01-01

    An analysis of the electron cyclotron emission (ECE) spectra emitted by a high-temperature tokamak plasma in the frequency range of the second and third harmonic of the electron cyclotron frequency is made, both in purely Maxwellian and in non-Maxwellian cases (i.e., in the presence of a current-carrying superthermal tail). The work is motivated mainly by the experimental observations made in the supershot plasmas of the Tokamak Fusion Test Reactor (TFTR), where a systematic disagreement is found between the T e measurements by second-harmonic ECE and Thomson scattering. We show that, by properly taking into account the overlap of superthermals-emitted third harmonic with second-harmonic bulk emission, the radiation temperature observed about the central frequency of the second harmonic may be enhanced up to 30%endash 40% compared to the corresponding thermal value. Moreover we show that, for parameters relevant to the International Thermonuclear Experimental Reactor (ITER) with T e (0)>7 keV, the overlap between the second and the downshifted third harmonic seriously affects the central plasma region, so that the X-mode emission at the second harmonic becomes unsuitable for local T e measurements. copyright 1997 American Institute of Physics

  13. Determination of composition and physical properties of partially ionized plasmas in the function of temperature

    International Nuclear Information System (INIS)

    Zaporowski, B.

    1992-01-01

    The investigations of various kinds of partially ionized plasma were conducted for the pressure of 0.1 MPa and in the range of temperature of 298.15 K to 24000 K. The physical properties of various kinds of partially ionized plasma depend mainly of their composition and temperature. The composition of particular kinds of partially ionized plasmas varies also in the function of temperature. Simultaneous going on of physical and chemical processes in plasma is the reason of difficulties in the calculations of plasma's physical properties. The use of the laws of macroscopic thermodynamics for the calculations of physical properties of partially ionized plasma is impossible. There are enough exact methods for measuring of physical properties of partially ionized plasma. For these reasons the theoretical method using the base of statistic physics was used to calculate the composition and physical properties of various kinds of partially ionized plasma. (author) 2 refs., 2 figs

  14. Carbon nanosheets by microwave plasma enhanced chemical vapor deposition in CH4-Ar system

    International Nuclear Information System (INIS)

    Wang Zhipeng; Shoji, Mao; Ogata, Hironori

    2011-01-01

    We employ a new gas mixture of CH 4 -Ar to fabricate carbon nanosheets by microwave plasma enhanced chemical vapor deposition at the growth temperature of less than 500 deg. C. The catalyst-free nanosheets possess flower-like structures with a large amount of sharp edges, which consist of a few layers of graphene sheets according to the observation by transmission electron microscopy. These high-quality carbon nanosheets demonstrated a faster electron transfer between the electrolyte and the nanosheet surface, due to their edge defects and graphene structures.

  15. Monte Carlo Sampling of Negative-temperature Plasma States

    International Nuclear Information System (INIS)

    John A. Krommes; Sharadini Rath

    2002-01-01

    A Monte Carlo procedure is used to generate N-particle configurations compatible with two-temperature canonical equilibria in two dimensions, with particular attention to nonlinear plasma gyrokinetics. An unusual feature of the problem is the importance of a nontrivial probability density function R0(PHI), the probability of realizing a set Φ of Fourier amplitudes associated with an ensemble of uniformly distributed, independent particles. This quantity arises because the equilibrium distribution is specified in terms of Φ, whereas the sampling procedure naturally produces particles states gamma; Φ and gamma are related via a gyrokinetic Poisson equation, highly nonlinear in its dependence on gamma. Expansion and asymptotic methods are used to calculate R0(PHI) analytically; excellent agreement is found between the large-N asymptotic result and a direct numerical calculation. The algorithm is tested by successfully generating a variety of states of both positive and negative temperature, including ones in which either the longest- or shortest-wavelength modes are excited to relatively very large amplitudes

  16. Plasma-enhanced synthesis of green flame retardant cellulosic materials

    Science.gov (United States)

    Totolin, Vladimir

    The natural fiber-containing fabrics and composites are more environmentally friendly, and are used in transportation (automobiles, aerospace), military applications, construction industries (ceiling paneling, partition boards), consumer products, etc. Therefore, the flammability characteristics of the composites based on polymers and natural fibers play an important role. This dissertation presents the development of plasma assisted - green flame retardant coatings for cellulosic substrates. The overall objective of this work was to generate durable flame retardant treatment on cellulosic materials. In the first approach sodium silicate layers were pre-deposited onto clean cotton substrates and cross linked using low pressure, non-equilibrium oxygen plasma. A statistical design of experiments was used to optimize the plasma parameters. The modified cotton samples were tested for flammability using an automatic 45° angle flammability test chamber. Aging tests were conducted to evaluate the coating resistance during the accelerated laundry technique. The samples revealed a high flame retardant behavior and good thermal stability proved by thermo-gravimetric analysis. In the second approach flame retardant cellulosic materials have been produced using a silicon dioxide (SiO2) network coating. SiO 2 network armor was prepared through hydrolysis and condensation of the precursor tetraethyl orthosilicate (TEOS), prior coating the substrates, and was cross linked on the surface of the substrates using atmospheric pressure plasma (APP) technique. Due to protection effects of the SiO2 network armor, the cellulosic based fibers exhibit enhanced thermal properties and improved flame retardancy. In the third approach, the TEOS/APP treatments were extended to linen fabrics. The thermal analysis showed a higher char content and a strong endothermic process of the treated samples compared with control ones, indicating a good thermal stability. Also, the surface analysis proved

  17. Diamond growth on Fe-Cr-Al alloy by H2-plasma enhanced graphite etching

    International Nuclear Information System (INIS)

    Li, Y. S.; Hirose, A.

    2007-01-01

    Without intermediate layer and surface pretreatment, adherent diamond films with high initial nucleation density have been deposited on Fe-15Cr-5Al (wt. %) alloy substrate. The deposition was performed using microwave hydrogen plasma enhanced graphite etching in a wide temperature range from 370 to 740 degree sign C. The high nucleation density and growth rate of diamond are primarily attributed to the unique precursors used (hydrogen plasma etched graphite) and the chemical nature of the substrate. The improvement in diamond adhesion to steel alloys is ascribed to the important role played by Al, mitigation of the catalytic function of iron by suppressing the preferential formation of loose graphite intermediate phase on steel surface

  18. Enhancement of wave growth for warm plasmas with a high-energy tail distribution

    Science.gov (United States)

    Thorne, Richard M.; Summers, Danny

    1991-01-01

    The classical linear theory of electromagnetic wave growth in a warm plasma is considered for waves propagating parallel to a uniform ambient magnetic field. Wave-growth rates are calculated for ion-driven right-hand mode waves for Kappa and Maxwellian particle distribution functions and for various values of the spectral index, the temperature anisotropy, and the ratio of plasma pressure to magnetic pressure appropriate to the solar wind. When the anisotropy is low the wave growth is limited to frequencies below the proton gyrofrequency and the growth rate increases dramatically as the spectral index is reduced. The growth rate for any Kappa distribution greatly exceeds that for a Maxwellian with the same bulk properties. For large thermal anisotropy the growth rate from either distribution is greatly enhanced. The growth rates from a Kappa distribution are generally larger than for a Maxwellian distribution, and significant wave growth occurs over a broader range of frequencies.

  19. Polycrystalline AlN films with preferential orientation by plasma enhanced chemical vapor deposition

    International Nuclear Information System (INIS)

    Sanchez, G.; Wu, A.; Tristant, P.; Tixier, C.; Soulestin, B.; Desmaison, J.; Bologna Alles, A.

    2008-01-01

    AlN thin films for acoustic wave devices were prepared by Microwave Plasma Enhanced Chemical Vapor Deposition under different process conditions, employing Si (100) and Pt (111)/SiO 2 /Si (100) substrates. The films were characterized by X-ray diffraction, Fourier transform infrared transmission spectroscopy, atomic force microscopy, scanning electron microscopy, and transmission electron microscopy. The values of the distance between the plasma and the tri-methyl-aluminum precursor injector, the radiofrequency bias potential, and the substrate temperature were central in the development of polycrystalline films. The choice of the chamber total pressure during deposition allowed for the development of two different crystallographic orientations, i.e., or . The film microstructures exhibited in general a column-like growth with rounded tops, an average grain size of about 40 nm, and a surface roughness lower than 20 nm under the best conditions

  20. Temperature dependence on plasma-induced damage and chemical reactions in GaN etching processes using chlorine plasma

    Science.gov (United States)

    Liu, Zecheng; Ishikawa, Kenji; Imamura, Masato; Tsutsumi, Takayoshi; Kondo, Hiroki; Oda, Osamu; Sekine, Makoto; Hori, Masaru

    2018-06-01

    Plasma-induced damage (PID) on GaN was optimally reduced by high-temperature chlorine plasma etching. Energetic ion bombardments primarily induced PID involving stoichiometry, surface roughness, and photoluminescence (PL) degradation. Chemical reactions under ultraviolet (UV) irradiation and chlorine radical exposure at temperatures higher than 400 °C can be controlled by taking into account the synergism of simultaneous photon and radical irradiations to effectively reduce PID.

  1. Low-temperature plasma simulations with the LSP PIC code

    Science.gov (United States)

    Carlsson, Johan; Khrabrov, Alex; Kaganovich, Igor; Keating, David; Selezneva, Svetlana; Sommerer, Timothy

    2014-10-01

    The LSP (Large-Scale Plasma) PIC-MCC code has been used to simulate several low-temperature plasma configurations, including a gas switch for high-power AC/DC conversion, a glow discharge and a Hall thruster. Simulation results will be presented with an emphasis on code comparison and validation against experiment. High-voltage, direct-current (HVDC) power transmission is becoming more common as it can reduce construction costs and power losses. Solid-state power-electronics devices are presently used, but it has been proposed that gas switches could become a compact, less costly, alternative. A gas-switch conversion device would be based on a glow discharge, with a magnetically insulated cold cathode. Its operation is similar to that of a sputtering magnetron, but with much higher pressure (0.1 to 0.3 Torr) in order to achieve high current density. We have performed 1D (axial) and 2D (axial/radial) simulations of such a gas switch using LSP. The 1D results were compared with results from the EDIPIC code. To test and compare the collision models used by the LSP and EDIPIC codes in more detail, a validation exercise was performed for the cathode fall of a glow discharge. We will also present some 2D (radial/azimuthal) LSP simulations of a Hall thruster. The information, data, or work presented herein was funded in part by the Advanced Research Projects Agency-Energy (ARPA-E), U.S. Department of Energy, under Award Number DE-AR0000298.

  2. Remote and direct plasma regions for low-temperature growth of carbon nanotubes on glass substrates for display applications

    International Nuclear Information System (INIS)

    Tabatabaei, M K; Ghafouri fard, H; Koohsorkhi, J; Khatami, S; Mohajerzadeh, S

    2011-01-01

    A novel method for growing carbon nanotubes (CNTs) on glass substrates is introduced in this study. A two-stage plasma was used to achieve low-temperature and vertically aligned CNTs. Ni deposited on indium tin oxide/glass substrate was used as the catalyst and hydrogen and acetylene were used as gas feeds. In this investigation a new technique was developed to grow vertically aligned CNTs at temperatures below 400 deg. C while CNT growth by plasma-enhanced chemical vapour deposition required high temperatures. Low-temperature growth of vertically aligned CNTs was suitable for the fabrication of micro-lens and self-oriented displays on glass substrates. Also, we have reported a new configuration for CNT-based display by means of controlling the refractive index of liquid crystal around the CNT by applying a proper voltage to the top and bottom array.

  3. Plasma Enhanced Growth of Carbon Nanotubes For Ultrasensitive Biosensors

    Science.gov (United States)

    Cassell, Alan M.; Li, J.; Ye, Q.; Koehne, J.; Chen, H.; Meyyappan, M.

    2004-01-01

    The multitude of considerations facing nanostructure growth and integration lends itself to combinatorial optimization approaches. Rapid optimization becomes even more important with wafer-scale growth and integration processes. Here we discuss methodology for developing plasma enhanced CVD growth techniques for achieving individual, vertically aligned carbon nanostructures that show excellent properties as ultrasensitive electrodes for nucleic acid detection. We utilize high throughput strategies for optimizing the upstream and downstream processing and integration of carbon nanotube electrodes as functional elements in various device types. An overview of ultrasensitive carbon nanotube based sensor arrays for electrochemical biosensing applications and the high throughput methodology utilized to combine novel electrode technology with conventional MEMS processing will be presented.

  4. Enhanced ion acceleration in transition from opaque to transparent plasmas

    Science.gov (United States)

    Mishra, R.; Fiuza, F.; Glenzer, S.

    2018-04-01

    Using particle-in-cell simulations, we investigate ion acceleration in the interaction of high intensity lasers with plasmas which transition from opaque to transparent during the interaction process. We show that the highest ion energies are achieved when the laser traverses the target around the peak intensity and re-heats the electron population responsible for the plasma expansion, enhancing the corresponding sheath electric field. This process can lead to an increase of up to 2x in ion energy when compared with the standard Target Normal Sheath Acceleration in opaque targets under the same laser conditions. A theoretical model is developed to predict the optimal target areal density as a function of laser intensity and pulse duration. A systematic parametric scan for a wide range of target densities and thicknesses is performed in 1D, 2D and 3D and shown consistent with the theory and with recent experimental results. These results open the way for a better optimization of the ion energy in future laser–solid experiments.

  5. Plasma-Sprayed Titanium Patterns for Enhancing Early Cell Responses

    Science.gov (United States)

    Shi, Yunqi; Xie, Youtao; Pan, Houhua; Zheng, Xuebin; Huang, Liping; Ji, Fang; Li, Kai

    2016-06-01

    Titanium coating has been widely used as a biocompatible metal in biomedical applications. However, the early cell responses and long-term fixation of titanium implants are not satisfied. To obviate these defects, in this paper, micro-post arrays with various widths (150-1000 μm) and intervals (100-300 μm) were fabricated on the titanium substrate by template-assisted plasma spraying technology. In vitro cell culture experiments showed that MC3T3-E1 cells exhibited significantly higher osteogenic differentiation as well as slightly improved adhesion and proliferation on the micro-patterned coatings compared with the traditional one. The cell number on the pattern with 1000 µm width reached 130% after 6 days of incubation, and the expressions of osteopontin (OPN) as well as osteocalcin (OC) were doubled. No obvious difference was found in cell adhesion on various size patterns. The present micro-patterned coatings proposed a new modification method for the traditional plasma spraying technology to enhance the early cell responses and convenience for the bone in-growth.

  6. Modeling of low temperature plasma for surface and Airborne decontamination

    NARCIS (Netherlands)

    Mihailova, D.; van Dijk, J.; Hagelaar, G.; Belenguer, P.; Guillot, P.

    2014-01-01

    This paper aims to study and develop new plasma-based technology for the next generation of molecular decontamination systems. A capacitively coupled plasma is considered for cleaning using the plasma fluxes directed to the walls. The model used for this purpose is the PLASIMO fluid module applied

  7. Destruction of α-synuclein based amyloid fibrils by a low temperature plasma jet

    Science.gov (United States)

    Karakas, Erdinc; Munyanyi, Agatha; Greene, Lesley; Laroussi, Mounir

    2010-10-01

    Amyloid fibrils are ordered beta-sheet aggregates that are associated with a number of neurodegenerative diseases such as Alzheimer and Parkinson. At present, there is no cure for these progressive and debilitating diseases. Here we report initial studies that indicate that low temperature atmospheric pressure plasma can break amyloid fibrils into smaller units in vitro. The plasma was generated by the "plasma pencil," a device capable of emitting a long, low temperature plasma plume/jet. This avenue of research may facilitate the development of a plasma-based medical treatment.

  8. Destruction of α-synuclein based amyloid fibrils by a low temperature plasma jet

    International Nuclear Information System (INIS)

    Karakas, Erdinc; Laroussi, Mounir; Munyanyi, Agatha; Greene, Lesley

    2010-01-01

    Amyloid fibrils are ordered beta-sheet aggregates that are associated with a number of neurodegenerative diseases such as Alzheimer and Parkinson. At present, there is no cure for these progressive and debilitating diseases. Here we report initial studies that indicate that low temperature atmospheric pressure plasma can break amyloid fibrils into smaller units in vitro. The plasma was generated by the 'plasma pencil', a device capable of emitting a long, low temperature plasma plume/jet. This avenue of research may facilitate the development of a plasma-based medical treatment.

  9. Enhancement of critical temperature in fractal metamaterial superconductors

    Energy Technology Data Exchange (ETDEWEB)

    Smolyaninov, Igor I., E-mail: smoly@umd.edu [Department of Electrical and Computer Engineering, University of Maryland, College Park, MD 20742 (United States); Smolyaninova, Vera N. [Department of Physics Astronomy and Geosciences, Towson University, 8000 York Road, Towson, MD 21252 (United States)

    2017-04-15

    Fractal metamaterial superconductor geometry has been suggested and analyzed based on the recently developed theoretical description of critical temperature increase in epsilon near zero (ENZ) metamaterial superconductors. Considerable enhancement of critical temperature has been predicted in such materials due to appearance of large number of additional poles in the inverse dielectric response function of the fractal. Our results agree with the recent observation (Fratini et al. Nature 466, 841 (2010)) that fractal defect structure promotes superconductivity.

  10. Introducing ultrasonic falling film evaporator for moderate temperature evaporation enhancement.

    Science.gov (United States)

    Dehbani, Maryam; Rahimi, Masoud

    2018-04-01

    In the present study, Ultrasonic Falling Film (USFF), as a novel technique has been proposed to increase the evaporation rate of moderate temperature liquid film. It is a proper method for some applications which cannot be performed at high temperature, such as foodstuff industry, due to their sensitivity to high temperatures. Evaporation rate of sodium chloride solution from an USFF on an inclined flat plate compared to that for Falling Film without ultrasonic irradiation (FF) at various temperatures was investigated. The results revealed that produced cavitation bubbles have different effects on evaporation rate at different temperatures. At lower temperatures, size fluctuation and collapse of bubbles and in consequence induced physical effects of cavitation bubbles resulted in more turbulency and evaporation rate enhancement. At higher temperatures, the behavior was different. Numerous created bubbles joined together and cover the plate surface, so not only decreased the ultrasound vibrations but also reduced the evaporation rate in comparison with FF. The highest evaporation rate enhancement of 353% was obtained at 40 °C at the lowest Reynolds number of 250. In addition, the results reveal that at temperature of 40 °C, USFF has the highest efficiency compared to FF. Copyright © 2017 Elsevier B.V. All rights reserved.

  11. Modeling ionospheric pre-reversal enhancement and plasma bubble growth rate using data assimilation

    Science.gov (United States)

    Rajesh, P. K.; Lin, C. C. H.; Chen, C. H.; Matsuo, T.

    2017-12-01

    We report that assimilating total electron content (TEC) into a coupled thermosphere-ionosphere model by using the ensemble Kalman filter results in improved specification and forecast of eastward pre-reversal enhancement (PRE) electric field (E-field). Through data assimilation, the ionospheric plasma density, thermospheric winds, temperature and compositions are adjusted simultaneously. The improvement of dusk-side PRE E-field over the prior state is achieved primarily by intensification of eastward neutral wind. The improved E-field promotes a stronger plasma fountain and deepens the equatorial trough. As a result, the horizontal gradients of Pedersen conductivity and eastward wind are increased due to greater zonal electron density gradient and smaller ion drag at dusk, respectively. Such modifications provide preferable conditions and obtain a strengthened PRE magnitude closer to the observation. The adjustment of PRE E-field is enabled through self-consistent thermosphere and ionosphere coupling processes captured in the model. The assimilative outputs are further utilized to calculate the flux tube integrated Rayleigh-Taylor instability growth rate during March 2015 for investigation of global plasma bubble occurrence. Significant improvements in the calculated growth rates could be achieved because of the improved update of zonal electric field in the data assimilation forecast. The results suggest that realistic estimate or prediction of plasma bubble occurrence could be feasible by taking advantage of the data assimilation approach adopted in this work.

  12. Modification of low temperature deposited LiMn2O4 thin film cathodes by oxygen plasma irradiation

    International Nuclear Information System (INIS)

    Chen, Chen Chung; Chiu, Kuo-Feng; Lin, Kun Ming; Lin, Hsin Chih

    2009-01-01

    Lithium manganese oxides have been deposited by radio frequency magnetron sputter deposition with relatively lower annealing temperatures and then post-treated with a radio frequency (rf) driven oxygen plasma. Following oxygen plasma irradiation, the film properties were modified, and the performance of the thin film cathode has been enhanced. The electrochemical properties of the treated thin-film cathodes were characterized and compared. The results showed that the samples with moderate plasma treatment also maintained good cyclic properties as cycled at a wide range potential window of 2.0 V-4.5 V. Its electrochemical properties were significantly improved by this process, even though the films were prepared under low annealing temperature.

  13. Growth kinetics and initial stage growth during plasma-enhanced Ti atomic layer deposition

    CERN Document Server

    Kim, H

    2002-01-01

    We have investigated the growth kinetics of plasma-enhanced Ti atomic layer deposition (ALD) using a quartz crystal microbalance. Ti ALD films were grown at temperatures from 20 to 200 deg. C using TiCl sub 4 as a source gas and rf plasma-produced atomic H as the reducing agent. Postdeposition ex situ chemical analyses of thin films showed that the main impurity is oxygen, mostly incorporated during the air exposure prior to analysis. The thickness per cycle, corresponding to the growth rate, was measured by quartz crystal microbalance as a function of various key growth parameters, including TiCl sub 4 and H exposure time, rf plasma power, and sample temperature. The growth rates were independent of TiCl sub 4 exposure above 1x10 sup 3 L, indicating typical ALD mode growth. The key kinetic parameters for Cl extraction reaction and TiCl sub 4 adsorption kinetics were obtained and the growth kinetics were modeled to predict the growth rates based upon these results. Also, the dependency of growth kinetics on d...

  14. Role of impurities in magnetically confined high temperature plasmas

    International Nuclear Information System (INIS)

    Barnett, C.F.

    1976-01-01

    A summary is given of the atomic physics concerned with plasma cooling by impurities and the limiting effect that impurities may have on heating of plasmas by neutral injection. A general description is given of the tokamak concept and the present and next generation experiments are described. The time and spatial behavior of O and Mo multicharged ions in present hydrogen plasmas is presented. This is followed by a discussion of the power loss from a plasma containing one percent Fe. Finally, the limitation of plasma heating by energetic H or D injection is summarized

  15. Production of a large diameter ECR plasma with low electron temperature

    International Nuclear Information System (INIS)

    Koga, Mayuko; Hishikawa, Yasuhiro; Tsuchiya, Hayato; Kawai, Yoshinobu

    2006-01-01

    A large diameter plasma over 300 mm in diameter is produced by electron cyclotron resonance (ECR) discharges using a cylindrical vacuum chamber of 400 mm in inner diameter. It is found that the plasma uniformity is improved by adding the nitrogen gas to pure Ar plasma. The electron temperature is decreased by adding the nitrogen gas. It is considered that the electron energy is absorbed in the vibrational energy of nitrogen molecules and the electron temperature decreases. Therefore, the adjunction of the nitrogen gas is considered to be effective for producing uniform and low electron temperature plasma

  16. Potential Formation in Front of an Electron Emitting Electrode in a Two-Electron Temperature Plasma

    International Nuclear Information System (INIS)

    Gyergyek, T.; Cercek, M.; Erzen, D.

    2003-01-01

    Plasma potential formation in the pre-sheath region of a floating electron emitting electrode (collector) is studied theoretically in a two-electron-temperature plasma using a static kinetic plasma-sheath model. Dependence of the collector floating potential, the plasma potential in the pre-sheath region, and the critical emission coefficient on the hot electron density and temperature is calculated. It is found that for high hot to cool electron temperature ratio a double layer like solutions exist in a certain range of hot to cool electron densities

  17. Temporal evolution of the spectral lines emission and temperatures in laser induced plasmas through characteristic parameters

    International Nuclear Information System (INIS)

    Bredice, F.; Pacheco Martinez, P.; Sánchez-Aké, C.; Villagrán-Muniz, M.

    2015-01-01

    In this work, we propose an extended Boltzmann plot method to determine the usefulness of spectral lines for plasma parameter calculations. Based on the assumption that transient plasmas are under ideal conditions during an specific interval of time Δt, (i.e. thin, homogeneous and in local thermodynamic equilibrium (LTE)), the associated Boltzmann plots describe a surface in the space defined by the coordinates X = Energy, Y = Time and Z = ln (λ jl I j /g j A jl ), where I j is the integrated intensity of the spectral line, g j is the statistical weight of the level j, λ jl is the wavelength of the considered line and A jl is its transition rate. In order to express the Boltzmann plot surface in terms of a reduced set of constants B i , and δ i , we developed as a power series of time, the logarithm of I n (t)/I n (t 0 ), where I n (t) is the integrated intensity of any spectral line at time t, and I n (t 0 ) at initial time. Moreover, the temporal evolution of the intensity of any spectral line and consequently the temperature of the plasma can be also expressed with these constants. The comparison of the temporal evolution of the line intensity calculated using these constants with their experimental values, can be used as a criterion for selecting useful lines in plasma analysis. Furthermore, this method can also be applied to determine self-absorption or enhancement of the spectral lines, to evaluate a possible departure of LTE, and to check or estimate the upper level energy value of any spectral line. An advantage of this method is that the value of these constants does not depend on the spectral response of the detection system, the uncertainty of the transition rates belonging to the analyzed spectral lines or any other time-independent parameters. In order to prove our method, we determined the constants B i and δ i and therefore the Boltzmann plot surface from the temporal evolution of carbon lines obtained from a plasma generated by a Nd:YAG laser

  18. Temporal evolution of the spectral lines emission and temperatures in laser induced plasmas through characteristic parameters

    Energy Technology Data Exchange (ETDEWEB)

    Bredice, F., E-mail: faustob@ciop.unlp.edu.ar [Centro de Investigaciones Ópticas, P.O. Box 3 C. P.1897 Gonnet, La Plata (Argentina); Pacheco Martinez, P. [Grupo de Espectroscopía Óptica de Emisión y Láser, Universidad del Atlántico, Barranquilla (Colombia); Sánchez-Aké, C.; Villagrán-Muniz, M. [Laboratorio de Fotofísica, Centro de Ciencias Aplicadas y Desarrollo Tecnológico, Universidad Nacional Autónoma de México, Apartado Postal 70-186, México D.F. 04510 (Mexico)

    2015-05-01

    In this work, we propose an extended Boltzmann plot method to determine the usefulness of spectral lines for plasma parameter calculations. Based on the assumption that transient plasmas are under ideal conditions during an specific interval of time Δt, (i.e. thin, homogeneous and in local thermodynamic equilibrium (LTE)), the associated Boltzmann plots describe a surface in the space defined by the coordinates X = Energy, Y = Time and Z = ln (λ{sub jl}I{sub j}/g{sub j}A{sub jl}), where I{sub j} is the integrated intensity of the spectral line, g{sub j} is the statistical weight of the level j, λ{sub jl} is the wavelength of the considered line and A{sub jl} is its transition rate. In order to express the Boltzmann plot surface in terms of a reduced set of constants B{sub i}, and δ{sub i}, we developed as a power series of time, the logarithm of I{sub n}(t)/I{sub n}(t{sub 0}), where I{sub n}(t) is the integrated intensity of any spectral line at time t, and I{sub n}(t{sub 0}) at initial time. Moreover, the temporal evolution of the intensity of any spectral line and consequently the temperature of the plasma can be also expressed with these constants. The comparison of the temporal evolution of the line intensity calculated using these constants with their experimental values, can be used as a criterion for selecting useful lines in plasma analysis. Furthermore, this method can also be applied to determine self-absorption or enhancement of the spectral lines, to evaluate a possible departure of LTE, and to check or estimate the upper level energy value of any spectral line. An advantage of this method is that the value of these constants does not depend on the spectral response of the detection system, the uncertainty of the transition rates belonging to the analyzed spectral lines or any other time-independent parameters. In order to prove our method, we determined the constants B{sub i} and δ{sub i} and therefore the Boltzmann plot surface from the temporal

  19. Observation of refraction and convergence of ion acoustic waves in a plasma with a temperature gradient

    International Nuclear Information System (INIS)

    Nishida, Y.; Hirose, A.

    1977-01-01

    The refraction and convergence of ion acoustic waves are experimentally investigated in a magnetized plasma with an electron temperature gradient. When ion acoustic waves are launched parallel to the field lines the waves converge toward the interior of the plasma column where the electron temperature is lower, in good agreement with theoretical prediction. Wave interference is also observed. (author)

  20. Oxidation of Inconel 625 superalloy upon treatment with oxygen or hydrogen plasma at high temperature

    Czech Academy of Sciences Publication Activity Database

    Vesel, A.; Drenik, A.; Elersic, K.; Mozetič, M.; Kovač, J.; Gyergyek, T.; Stöckel, Jan; Varju, Jozef; Pánek, Radomír; Balat-Pichelin, M.

    2014-01-01

    Roč. 305, June (2014), s. 674-682 ISSN 0169-4332 R&D Projects: GA MŠk(CZ) LM2011021 Institutional support: RVO:61389021 Keywords : Inconel * Oxidation * High temperature * Oxygen plasma * Hydrogen plasma Subject RIV: BL - Plasma and Gas Discharge Physics OBOR OECD: Fluids and plasma physics (including surface physics) Impact factor: 2.711, year: 2014 https://www.sciencedirect.com/science/article/pii/S0169433214007119

  1. Spectroscopic measurements of the density and electronic temperature at the plasma edge in Tore Supra

    International Nuclear Information System (INIS)

    Lediankine, A.

    1996-01-01

    The profiles of temperature and electronic density at the plasma edge are important to study the wall-plasma interaction and the radiative layers in the Tokamak plasmas. The laser ablation technique of the lithium allows to measure the profile of electronic density. To measure the profile of temperature, it has been used for the first time, the injection of a fluorine neutral atoms beam. The experiments, the results are described in this work. (N.C.)

  2. Perspective: The physics, diagnostics, and applications of atmospheric pressure low temperature plasma sources used in plasma medicine

    Science.gov (United States)

    Laroussi, M.; Lu, X.; Keidar, M.

    2017-07-01

    Low temperature plasmas have been used in various plasma processing applications for several decades. But it is only in the last thirty years or so that sources generating such plasmas at atmospheric pressure in reliable and stable ways have become more prevalent. First, in the late 1980s, the dielectric barrier discharge was used to generate relatively large volume diffuse plasmas at atmospheric pressure. Then, in the early 2000s, plasma jets that can launch cold plasma plumes in ambient air were developed. Extensive experimental and modeling work was carried out on both methods and much of the physics governing such sources was elucidated. Starting in the mid-1990s, low temperature plasma discharges have been used as sources of chemically reactive species that can be transported to interact with biological media, cells, and tissues and induce impactful biological effects. However, many of the biochemical pathways whereby plasma affects cells remain not well understood. This situation is changing rather quickly because the field, known today as "plasma medicine," has experienced exponential growth in the last few years thanks to a global research community that engaged in fundamental and applied research involving the use of cold plasma for the inactivation of bacteria, dental applications, wound healing, and the destruction of cancer cells/tumors. In this perspective, the authors first review the physics as well as the diagnostics of the principal plasma sources used in plasma medicine. Then, brief descriptions of their biomedical applications are presented. To conclude, the authors' personal assessment of the present status and future outlook of the field is given.

  3. The Influence of Hot-Rolled Temperature on Plasma Nitriding Behavior of Iron-Based Alloys

    Science.gov (United States)

    El-Hossary, F. M.; Khalil, S. M.; Lotfy, Kh.; Kassem, M. A.

    2009-07-01

    Experiments were performed with an aim of studying the effect of hot-rolled temperature (600 and 900°C) on radio frequency (rf) plasma nitriding of Fe93Ni4Zr3 alloy. Nitriding was carried out for 10 min in a nitrogen atmosphere at a base pressure of 10-2 mbarr. Different continuous plasma processing powers of 300-550 W in steps 50 W or less were applied. Nitrided hot-rolled specimens were characterized by optical microscopy (OM), X-ray diffraction (XRD) and microhardness measurements. The results reveal that the surface of hot-rolled rf plasma nitrided specimens at 600°C is characterized with a fine microstructure as a result of the high nitrogen solubility and diffusivity. Moreover, the hot-rolled treated samples at 600°C exhibit higher microhardness value than the associated values of hot-rolled treated samples at 900°C. The enhancement of microhardness is due to precipitation and predominance of new phases ( γ and ɛ phases). Mainly, this conclusion has been attributed to the high defect densities and small grain sizes of the samples hot-rolled at 600°C. Generally, the refinement of grain size plays a dramatic role in improvement of mechanical properties of tested samples.

  4. Preparation of carbon nanotubes with different morphology by microwave plasma enhanced chemical vapour deposition

    Energy Technology Data Exchange (ETDEWEB)

    Duraia, El-Shazly M. [Suez Canal University, Faculty of Science, Physics Department, Ismailia (Egypt); Al-Farabi Kazakh National University, 71 Al-Farabi av., 050038 Almaty (Kazakhstan); Institute of Physics and Technology, Ibragimov Street 11, 050032 Almaty (Kazakhstan); Mansurov, Zulkhair [Al-Farabi Kazakh National University, 71 Al-Farabi av., 050038 Almaty (Kazakhstan); Tokmoldin, S.Zh. [Institute of Physics and Technology, Ibragimov Street 11, 050032 Almaty (Kazakhstan)

    2010-04-15

    In this work we present a part of our results about the preparation of carbon nanotube with different morphologies by using microwave plasma enhanced chemical vapour deposition MPECVD. Well aligned, curly, carbon nanosheets, coiled carbon sheets and carbon microcoils have been prepared. We have investigated the effect of the different growth condition parameters such as the growth temperature, pressure and the hydrogen to methane flow rate ratio on the morphology of the carbon nanotubes. The results showed that there is a great dependence of the morphology of carbon nanotubes on these parameters. The yield of the carbon microcoils was high when the growth temperature was 700 C. There is a linear relation between the growth rate and the methane to hydrogen ratio. The effect of the gas pressure on the CNTs was also studied. Our samples were investigated by scanning electron microscope and Raman spectroscopy (copyright 2010 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim) (orig.)

  5. Patterned deposition by atmospheric pressure plasma-enhanced spatial atomic layer deposition

    NARCIS (Netherlands)

    Poodt, P.; Kniknie, B.J.; Branca, A.; Winands, G.J.J.; Roozeboom, F.

    2011-01-01

    An atmospheric pressure plasma enhanced atomic layer deposition reactor has been developed, to deposit Al2O3 films from trimethyl aluminum and an He/O2 plasma. This technique can be used for 2D patterned deposition in a single in-line process by making use of switched localized plasma sources. It

  6. Influence of emitter temperature on the energy deposition in a low-pressure plasma

    International Nuclear Information System (INIS)

    Levko, Dmitry; Raja, Laxminarayan L.

    2016-01-01

    The influence of emitter temperature on the energy deposition into low-pressure plasma is studied by the self-consistent one-dimensional Particle-in-Cell Monte Carlo Collisions model. Depending on the emitter temperature, different modes of discharge operation are obtained. The mode type depends on the plasma frequency and does not depend on the ratio between the densities of beam and plasma electrons. Namely, plasma is stable when the plasma frequency is small. For this plasma, the energy transfer from emitted electrons to plasma electrons is inefficient. The increase in the plasma frequency results first in the excitation of two-stream electron instability. However, since the thermal velocity of plasma electrons is smaller than the electrostatic wave velocity, the resonant wave-particle interaction is inefficient for the energy deposition into the plasma. Further increase in the plasma frequency leads to the distortion of beam of emitted electrons. Then, the electrostatic wave generated due to two-stream instability decays into multiple slower waves. Phase velocities of these waves are comparable with the thermal velocity of plasma electrons which makes possible the resonant wave-particle interaction. This results in the efficient energy deposition from emitted electrons into the plasma.

  7. Plasma temperature during methylene blue/light treatment influences virus inactivation capacity and product quality.

    Science.gov (United States)

    Gravemann, U; Handke, W; Sumian, C; Alvarez, I; Reichenberg, S; Müller, T H; Seltsam, A

    2018-02-27

    Photodynamic treatment using methylene blue (MB) and visible light is in routine use for pathogen inactivation of human plasma in different countries. Ambient and product temperature conditions for human plasma during production may vary between production sites. The influence of different temperature conditions on virus inactivation capacity and plasma quality of the THERAFLEX MB-Plasma procedure was investigated in this study. Plasma units equilibrated to 5 ± 2°C, room temperature (22 ± 2°C) or 30 ± 2°C were treated with MB/light and comparatively assessed for the inactivation capacity for three different viruses, concentrations of MB and its photoproducts, activity of various plasma coagulation factors and clotting time. Reduced solubility of the MB pill was observed at 5 ± 2°C. Photocatalytic degradation of MB increased with increasing temperature, and the greatest formation of photoproducts (mainly azure B) occurred at 30 ± 2°C. Inactivation of suid herpesvirus, bovine viral diarrhoea virus and vesicular stomatitis virus was significantly lower at 5 ± 2°C than at higher temperatures. MB/light treatment affected clotting times and the activity of almost all investigated plasma proteins. Factor VIII (-17·7 ± 8·3%, 22 ± 2°C) and fibrinogen (-14·4 ± 16·4%, 22 ± 2°C) showed the highest decreases in activity. Increasing plasma temperatures resulted in greater changes in clotting time and higher losses of plasma coagulation factor activity. Temperature conditions for THERAFLEX MB-Plasma treatment must be carefully controlled to assure uniform quality of pathogen-reduced plasma in routine production. Inactivation of cooled plasma is not recommended. © 2018 International Society of Blood Transfusion.

  8. Enhancement of corrosion resistance for plasma nitrided AISI 4140 steel by plain air plasma post-oxidizing

    Energy Technology Data Exchange (ETDEWEB)

    Wu, Jiqiang; Liu, Han; Ye, Xuemei [Jiangsu Key Laboratory of Materials Surface Technology, Changzhou University, Changzhou 213164 (China); Chai, Yating [Materials Research and Education Center, Auburn University, AL 36849 (United States); Hu, Jing, E-mail: jinghoo@126.com [Jiangsu Key Laboratory of Materials Surface Technology, Changzhou University, Changzhou 213164 (China); Materials Research and Education Center, Auburn University, AL 36849 (United States)

    2015-05-25

    Highlights: • Plain air was primarily used for plasma post-oxidation for AISI 4140 steel. • A thin iron oxide layer composed of Fe{sub 3}O{sub 4} to Fe{sub 2}O{sub 3} was formed on top of the compound layer. • The ratio of Fe{sub 3}O{sub 4} to Fe{sub 2}O{sub 3} was closely related to the post-oxidizing conditions. • Post-oxidizing at 673 K for 60 min brought out highest ratio of Fe{sub 3}O{sub 4} to Fe{sub 2}O{sub 3} and optimum corrosion resistance. - Abstract: Plasma post-oxidizing was conducted immediately after plasma nitriding in the same equipment for AISI 4140 steel, and plain air was used as the oxygen bearing gas. The cross-sectional microstructures of the treated samples were observed by optical metallography and scanning electron microcopy (SEM), and the thickness of compound layer was measured accordingly. The phases were determined by X-ray diffraction (XRD), corrosion resistance was evaluated by electrochemical polarization, and the surface morphology before and after polarization test was also observed by SEM. Meanwhile, standard Gibbs free energy of the oxidation reactions existed in Fe–O system was calculated. The results show that a thin iron oxide layer composed of magnetite (Fe{sub 3}O{sub 4}) and hematite (Fe{sub 2}O{sub 3}) is formed on top of the compound layer during plasma post-oxidizing process, and the ratio of magnetite (Fe{sub 3}O{sub 4}) to hematite (Fe{sub 2}O{sub 3}) is depended on plasma post-oxidizing temperature and time. Highest ratio of Fe{sub 3}O{sub 4} to Fe{sub 2}O{sub 3} is obtained while post-oxidizing at 673 K for 60 min due to lower standard Gibbs free energy and appropriate forming rate for the formation of Fe{sub 3}O{sub 4} at this temperature. The thin oxide layer brings out significant enhancement of corrosion resistance, especially at higher ratios of Fe{sub 3}O{sub 4} to Fe{sub 2}O{sub 3}, due to the dense and adherent characteristic of Fe{sub 3}O{sub 4} oxide. Surface images of the post-oxidizing specimen

  9. Resonance-enhanced laser-induced plasma spectroscopy for sensitive elemental analysis: Elucidation of enhancement mechanisms

    International Nuclear Information System (INIS)

    Lui, S.L.; Cheung, N.H.

    2002-01-01

    When performing laser-induced plasma spectroscopy for elemental analysis, the analyte signal-to-noise ratio increased from four to over fifty if the plume was reheated by a dye laser pulse tuned to resonant absorption. Time-resolved studies showed that the enhancement was not due to resonance photoionization. Rather, efficient and controlled rekindling of a larger plume volume was the key mechanism. The signal-to-noise ratio further increased to over a hundred if the atmosphere was replaced by a low-pressure heavy inert gas. The ambient gas helped confine and thermally insulate the expanding vapor

  10. Enhancement of Combustion and Flame Stabilization Using Transient Non-Equilibrium Plasma

    National Research Council Canada - National Science Library

    Ju, Yiguang; Ombrello, Timothy; Fridman, Alexander; Gutsol, Alexander; Gangoli, Shailesh

    2007-01-01

    .... Laser diagnostics of flame temperature and OH distribution using planar Rayleigh scattering and planar laser-induced fluorescence revealed that the plasma-flame interaction at low air temperature...

  11. Study on factors affecting the droplet temperature in plasma MIG welding process

    Science.gov (United States)

    Mamat, Sarizam Bin; Tashiro, Shinichi; Tanaka, Manabu; Yusoff, Mahani

    2018-04-01

    In the present study, the mechanism to control droplet temperature in the plasma MIG welding was discussed based on the measurements of the droplet temperature for a wide range of MIG currents with different plasma electrode diameters. The measurements of the droplet temperatures were conducted using a two color temperature measurement method. The droplet temperatures in the plasma MIG welding were then compared with those in the conventional MIG welding. As a result, the droplet temperature in the plasma MIG welding was found to be reduced in comparison with the conventional MIG welding under the same MIG current. Especially when the small plasma electrode diameter was used, the decrease in the droplet temperature reached maximally 500 K. Also, for a particular WFS, the droplet temperatures in the plasma MIG welding were lower than those in the conventional MIG welding. It is suggested that the use of plasma contributes to reducing the local heat input into the base metal by the droplet. The presence of the plasma surrounding the wire is considered to increase the electron density in its vicinity, resulting in the arc attachment expanding upwards along the wire surface to disperse the MIG current. This dispersion of MIG current causes a decrease in current density on the droplet surface, lowering the droplet temperature. Furthermore, dispersed MIG current also weakens the electromagnetic pinch force acting on the neck of the wire above the droplet. This leads to a larger droplet diameter with increased surface area through lower frequency of droplet detachment to decrease the MIG current density on the droplet surface, as compared to the conventional MIG welding at the same MIG current. Thus, the lower droplet temperature is caused by the reduction of heat flux into the droplet. Consequently, the mechanism to control droplet temperature in the plasma MIG welding was clarified.

  12. Helicon plasma ion temperature measurements and observed ion cyclotron heating in proto-MPEX

    Science.gov (United States)

    Beers, C. J.; Goulding, R. H.; Isler, R. C.; Martin, E. H.; Biewer, T. M.; Caneses, J. F.; Caughman, J. B. O.; Kafle, N.; Rapp, J.

    2018-01-01

    The Prototype-Material Plasma Exposure eXperiment (Proto-MPEX) linear plasma device is a test bed for exploring and developing plasma source concepts to be employed in the future steady-state linear device Material Plasma Exposure eXperiment (MPEX) that will study plasma-material interactions for the nuclear fusion program. The concept foresees using a helicon plasma source supplemented with electron and ion heating systems to reach necessary plasma conditions. In this paper, we discuss ion temperature measurements obtained from Doppler broadening of spectral lines from argon ion test particles. Plasmas produced with helicon heating alone have average ion temperatures downstream of the Helicon antenna in the range of 3 ± 1 eV; ion temperature increases to 10 ± 3 eV are observed with the addition of ion cyclotron heating (ICH). The temperatures are higher at the edge than the center of the plasma either with or without ICH. This type of profile is observed with electrons as well. A one-dimensional RF antenna model is used to show where heating of the plasma is expected.

  13. Using the low-temperature plasma in cement production

    International Nuclear Information System (INIS)

    Sazonova, N A; Skripnikova, N K

    2015-01-01

    The calculation of the raw-material mixtures and mineralogical composition of the cement clinkers which are synthezed on their base taking into account the disbalanced crystallization of the melting and glassing under conditions of the low-temperature plasma was performed. The difference of the actual values from the calculated ones is 0.69-3.73%. The composition which is characterized as the saturation coefficient 0,88; the silicate module - 3.34, the alumina module - 2.52 in melting of which the alite in amount 78.7%; 3CaO·SiO 2 - 4%; 3CaO·Al 2 O 3 - 9.8%; 12CaO·7Al 2 O 3 -2.9%; CaO free - 1% formed using the lime-stone from the quarry «Pereval» in the town of Slyudyanka and the clay from the deposit «Maximovski» in Irkutsk Region is considered as the optimal one. The structure of the melted clinker is represented as the metastable minerals of alite in the lamellar form with the dimensions up to (3-20)×(80-400) μm and the ratio of length to width 26.6-133. The elongated crystal form may stipulate the high cement activity based on the melted clinkers, which is 82.7-84.2 MPa. Valid- ing the revealed high activity of the viscous substance was confirmed by the results of the scanning electronic microscopy, X-ray phase analysis, with using of which the quantitative and qualitative analyses of the clinker minerals having the deformed crystalic lattice; were performed the morphology of the minerals in the clinker and cement stone, received on its ground, was studied. (paper)

  14. Plasma sheath physics and dose uniformity in enhanced glow discharge plasma immersion ion implantation and deposition

    International Nuclear Information System (INIS)

    Li Liuhe; Li Jianhui; Kwok, Dixon T. K.; Chu, Paul K.; Wang Zhuo

    2009-01-01

    Based on the multiple-grid particle-in-cell code, an advanced simulation model is established to study the sheath physics and dose uniformity along the sample stage in order to provide the theoretical basis for further improvement of enhanced glow discharge plasma immersion ion implantation and deposition. At t=7.0 μs, the expansion of the sheath in the horizontal direction is hindered by the dielectric cage. The electron focusing effect is demonstrated by this model. Most of the ions at the inside wall of the cage are implanted into the edge of the sample stage and a relatively uniform ion fluence distribution with a large peak is observed at the end. Compared to the results obtained from the previous model, a higher implant fluence and larger area of uniformity are disclosed.

  15. Heteroepitaxial Growth of Germanium-on-Silicon Using Ultrahigh-Vacuum Chemical Vapor Deposition with RF Plasma Enhancement

    Science.gov (United States)

    Alharthi, Bader; Grant, Joshua M.; Dou, Wei; Grant, Perry C.; Mosleh, Aboozar; Du, Wei; Mortazavi, Mansour; Li, Baohua; Naseem, Hameed; Yu, Shui-Qing

    2018-05-01

    Germanium (Ge) films have been grown on silicon (Si) substrate by ultrahigh-vacuum chemical vapor deposition with plasma enhancement (PE). Argon plasma was generated using high-power radiofrequency (50 W) to assist in germane decomposition at low temperature. The growth temperature was varied in the low range of 250°C to 450°C to make this growth process compatible with complementary metal-oxide-semiconductor technology. The material and optical properties of the grown Ge films were investigated. The material quality was determined by Raman and x-ray diffraction techniques, revealing growth of crystalline films in the temperature range of 350°C to 450°C. Photoluminescence spectra revealed improved optical quality at growth temperatures of 400°C and 450°C. Furthermore, material quality study using transmission electron microscopy revealed existence of defects in the Ge layer grown at 400°C. Based on the etch pit density, the average threading dislocation density in the Ge layer obtained at this growth temperature was measured to be 4.5 × 108 cm-2. This result was achieved without any material improvement steps such as use of graded buffer or thermal annealing. Comparison between PE and non-plasma-enhanced growth, in the same machine at otherwise the same growth conditions, indicated increased growth rate and improved material and optical qualities for PE growth.

  16. Nanoparticle manipulation in the near-substrate areas of low-temperature, high-density rf plasmas

    International Nuclear Information System (INIS)

    Rutkevych, P.P.; Ostrikov, K.; Xu, S.

    2005-01-01

    Manipulation of a single nanoparticle in the near-substrate areas of high-density plasmas of low-temperature glow discharges is studied. It is shown that the nanoparticles can be efficiently manipulated by the thermophoretic force controlled by external heating of the substrate stage. Particle deposition onto or repulsion from nanostructured carbon surfaces critically depends on the values of the neutral gas temperature gradient in the near-substrate areas, which is directly measured in situ in different heating regimes by originally developed temperature gradient probe. The measured values of the near-surface temperature gradient are used in the numerical model of nanoparticle dynamics in a variable-length presheath. Specific conditions enabling the nanoparticle to overcome the repulsive potential and deposit on the substrate during the discharge operation are investigated. The results are relevant to fabrication of various nanostructured films employing structural incorporation of the plasma-grown nanoparticles, in particular, to nanoparticle deposition in the plasma-enhanced chemical-vapor deposition of carbon nanostructures in hydrocarbon-based plasmas

  17. Nonlocal collisionless and collisional electron transport in low temperature plasmas

    Science.gov (United States)

    Kaganovich, Igor

    2009-10-01

    The purpose of the talk is to describe recent advances in nonlocal electron kinetics in low-pressure plasmas. A distinctive property of partially ionized plasmas is that such plasmas are always in a non-equilibrium state: the electrons are not in thermal equilibrium with the neutral species and ions, and the electrons are also not in thermodynamic equilibrium within their own ensemble, which results in a significant departure of the electron velocity distribution function from a Maxwellian. These non-equilibrium conditions provide considerable freedom to choose optimal plasma parameters for applications, which make gas discharge plasmas remarkable tools for a variety of plasma applications, including plasma processing, discharge lighting, plasma propulsion, particle beam sources, and nanotechnology. Typical phenomena in such discharges include nonlocal electron kinetics, nonlocal electrodynamics with collisionless electron heating, and nonlinear processes in the sheaths and in the bounded plasmas. Significant progress in understanding the interaction of electromagnetic fields with real bounded plasma created by this field and the resulting changes in the structure of the applied electromagnetic field has been one of the major achievements of the last decade in this area of research [1-3]. We show on specific examples that this progress was made possible by synergy between full scale particle-in-cell simulations, analytical models, and experiments. In collaboration with Y. Raitses, A.V. Khrabrov, Princeton Plasma Physics Laboratory, Princeton, NJ, USA; V.I. Demidov, UES, Inc., 4401 Dayton-Xenia Rd., Beavercreek, OH 45322, USA and AFRL, Wright-Patterson AFB, OH 45433, USA; and D. Sydorenko, University of Alberta, Edmonton, Canada. [4pt] [1] D. Sydorenko, A. Smolyakov, I. Kaganovich, and Y. Raitses, IEEE Trans. Plasma Science 34, 895 (2006); Phys. Plasmas 13, 014501 (2006); 14 013508 (2007); 15, 053506 (2008). [0pt] [2] I. D. Kaganovich, Y. Raitses, D. Sydorenko, and

  18. Tunnel probes for measurements of the electron and ion temperature in fusion plasmas

    Czech Academy of Sciences Publication Activity Database

    Gunn, J. P.; Schrittwieser, R.; Balan, P.; Ionita, C.; Stöckel, Jan; Adámek, Jiří; Ďuran, Ivan; Hron, Martin; Pánek, Radomír; Bařina, O.; Hrach, R.; Vicher, M.; Van Oost, G.; Van Rompuy, T.; Martines, E.

    2004-01-01

    Roč. 75, č. 10 (2004), s. 4328-4330 ISSN 0034-6748. [Topical Conference on High-Temperature Plasma Diagnostics/15th./. San Diego, 19.04.2004-22.04.2004] R&D Projects: GA ČR GA202/03/0786 Institutional research plan: CEZ:AV0Z2043910 Keywords : Tokamak * electron temperature * ion temperature * plasma diagnostics Subject RIV: BG - Nuclear, Atomic and Molecular Physics, Colliders Impact factor: 1.226, year: 2004

  19. Time-dependent electron temperature diagnostics for high-power aluminum z-pinch plasmas

    International Nuclear Information System (INIS)

    Sanford, T.W.L.; Nash, T.J.; Mock, R.C.

    1996-08-01

    Time-resolved x-ray pinhole photographs and time-integrated radially-resolved x-ray crystal-spectrometer measurements of azimuthally-symmetric aluminum-wire implosions suggest that the densest phase of the pinch is composed of a hot plasma core surrounded by a cooler plasma halo. The slope of the free-bound x-ray continuum, provides a time-resolved, model-independent diagnostic of the core electron temperature. A simultaneous measurement of the time-resolved K-shell line spectra provides the electron temperature of the spatially averaged plasma. Together, the two diagnostics support a 1-D Radiation-Hydrodynamic model prediction of a plasma whose thermalization on axis produces steep radial gradients in temperature, from temperatures in excess of a kilovolt in the core to below a kilovolt in the surrounding plasma halo

  20. Experimental Research of Inactivation Effect of Low-Temperature Plasma on Bacteria

    International Nuclear Information System (INIS)

    Shi Xingmin; Yuan Yukang; Sun Yanzhou; Yuan Wang; Fengling, Peng; Qiu Yuchang

    2006-01-01

    The killing logarithms index in killing a vegetative form in an explosure of about 90 s and a spore in an explosure of about 120 s, by using a low-temperature plasma produced by dielectric barrier discharge (DBD), reached 5. The speed in killing the strains tested, by using a low-temperature plasma, was the highest with E. Coli, then S. Aureus and B. Subtilis var niger spore. The results of the scanning electron microscope showed that the low-temperature plasma destroyed the outer structure of the bacteria and that the vegetative form was more susceptible to the inactivation effect of the low-temperature plasma than was the spore. This indicated that the effects of the high voltage and high velocity particle flow, in plasma, penetrating through the outer structure of the bacteria might play a dominant role during the inactivation of the bacteria

  1. Enhanced nonlinear iterative techniques applied to a nonequilibrium plasma flow

    International Nuclear Information System (INIS)

    Knoll, D.A.

    1998-01-01

    The authors study the application of enhanced nonlinear iterative methods to the steady-state solution of a system of two-dimensional convection-diffusion-reaction partial differential equations that describe the partially ionized plasma flow in the boundary layer of a tokamak fusion reactor. This system of equations is characterized by multiple time and spatial scales and contains highly anisotropic transport coefficients due to a strong imposed magnetic field. They use Newton's method to linearize the nonlinear system of equations resulting from an implicit, finite volume discretization of the governing partial differential equations, on a staggered Cartesian mesh. The resulting linear systems are neither symmetric nor positive definite, and are poorly conditioned. Preconditioned Krylov iterative techniques are employed to solve these linear systems. They investigate both a modified and a matrix-free Newton-Krylov implementation, with the goal of reducing CPU cost associated with the numerical formation of the Jacobian. A combination of a damped iteration, mesh sequencing, and a pseudotransient continuation technique is used to enhance global nonlinear convergence and CPU efficiency. GMRES is employed as the Krylov method with incomplete lower-upper (ILU) factorization preconditioning. The goal is to construct a combination of nonlinear and linear iterative techniques for this complex physical problem that optimizes trade-offs between robustness, CPU time, memory requirements, and code complexity. It is shown that a mesh sequencing implementation provides significant CPU savings for fine grid calculations. Performance comparisons of modified Newton-Krylov and matrix-free Newton-Krylov algorithms will be presented

  2. Role of Plasma Temperature and Residence Time in Stagnation Plasma Synthesis of c-BN Nanopowders

    Science.gov (United States)

    2013-01-01

    7 A plasma ion source creates the ions, which are then separated by magnetic mass separation to guide the separate beams into a deposition...generator is the soul contributor to sustaining the plasma. Figure 3.3 Plasma synthesis setup. Solid powder-form precursors are sublimated and...operation frequency gives the proper magnetic field skin depth to match the overall plasma torch diameter. The magnetic field skin depth is inversely

  3. The effect of low temperature plasma on DNA damage of maize seeds

    International Nuclear Information System (INIS)

    Uhrin, F.; Ondriasova, K.; Kyzek, S.; Galova, E.; Medvecka, V.; Zahoranova, A.

    2017-01-01

    It is known that the low temperature plasma shows antimicrobial and disinfecting effects. It also supports the seed germination and it is used in many fields of common life. But there is just a few scientific papers dealing with the genotoxic properties of plasma. In our work, we try to determine the relative rate of DNA double strand breaks formation resulting from the low temperature plasma treatment in the seeds of Zea mays L. using the constant field gel electrophoresis (CFGE). We compared DNA damage in seedlings resulting from plasma and zeocin treatment with seedlings, which seeds were treated just with zeocin. (authors)

  4. A handheld low temperature atmospheric pressure air plasma gun for nanomaterial synthesis in liquid phase

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Shuang; Wang, Kaile; Zuo, Shasha; Liu, Jiahui [Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); Zhang, Jue, E-mail: zhangjue@pku.edu.cn; Fang, Jing [Academy for Advanced Interdisciplinary Studies, Peking University, Beijing 100871 (China); College of Engineering, Peking University, Beijing 100871 (China)

    2015-10-15

    A handheld low temperature atmospheric pressure air plasma gun based on a dielectric barrier structure with hollow electrodes was proposed. The portable plasma gun with an embedded mini air pump was driven by a 12 V direct voltage battery. The air plasma jet generated from the gun could be touched without a common shock hazard. Besides working in air, the plasma gun can also work in water. The diagnostic result of optical emission spectroscopy showed the difference in reactive species of air plasma jet between in air and in water. The plasma gun was excited in 20 ml chloroauric acid aqueous solution with a concentration of 1.214 mM. A significant amount of gold nanoparticles were synthesized after 2 min continuous discharge. The plasma gun with these unique features is applicable in plasma medicine, etching, and s-nthesis of nanomaterials.

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

    International Nuclear Information System (INIS)

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

    2013-01-01

    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) N 2 /H 2 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 C-N, C=N, and C≡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.

  6. Treatment of Candida albicans biofilms with low-temperature plasma induced by dielectric barrier discharge and atmospheric pressure plasma jet

    International Nuclear Information System (INIS)

    Koban, Ina; Welk, Alexander; Meisel, Peter; Holtfreter, Birte; Kocher, Thomas; Matthes, Rutger; Huebner, Nils-Olaf; Kramer, Axel; Sietmann, Rabea; Kindel, Eckhard; Weltmann, Klaus-Dieter

    2010-01-01

    Because of some disadvantages of chemical disinfection in dental practice (especially denture cleaning), we investigated the effects of physical methods on Candida albicans biofilms. For this purpose, the antifungal efficacy of three different low-temperature plasma devices (an atmospheric pressure plasma jet and two different dielectric barrier discharges (DBDs)) on Candida albicans biofilms grown on titanium discs in vitro was investigated. As positive treatment controls, we used 0.1% chlorhexidine digluconate (CHX) and 0.6% sodium hypochlorite (NaOCl). The corresponding gas streams without plasma ignition served as negative treatment controls. The efficacy of the plasma treatment was determined evaluating the number of colony-forming units (CFU) recovered from titanium discs. The plasma treatment reduced the CFU significantly compared to chemical disinfectants. While 10 min CHX or NaOCl exposure led to a CFU log 10 reduction factor of 1.5, the log 10 reduction factor of DBD plasma was up to 5. In conclusion, the use of low-temperature plasma is a promising physical alternative to chemical antiseptics for dental practice.

  7. Treatment of Candida albicans biofilms with low-temperature plasma induced by dielectric barrier discharge and atmospheric pressure plasma jet

    Energy Technology Data Exchange (ETDEWEB)

    Koban, Ina; Welk, Alexander; Meisel, Peter; Holtfreter, Birte; Kocher, Thomas [Unit of Periodontology, Dental School, University of Greifswald, Rotgerberstr. 8, 17475 Greifswald (Germany); Matthes, Rutger; Huebner, Nils-Olaf; Kramer, Axel [Institute for Hygiene and Environmental Medicine, University of Greifswald, Walther-Rathenau-Str. 49 a, 17487 Greifswald (Germany); Sietmann, Rabea [Institute of Microbiology, University of Greifswald, Friedrich-Ludwig-Jahn-Str. 15, 17487 Greifswald (Germany); Kindel, Eckhard; Weltmann, Klaus-Dieter, E-mail: ina.koban@uni-greifswald.d [Leibniz Institute for Plasma Science and Technology (INP), Felix-Hausdorff-Str. 2, 17489 Greifswald (Germany)

    2010-07-15

    Because of some disadvantages of chemical disinfection in dental practice (especially denture cleaning), we investigated the effects of physical methods on Candida albicans biofilms. For this purpose, the antifungal efficacy of three different low-temperature plasma devices (an atmospheric pressure plasma jet and two different dielectric barrier discharges (DBDs)) on Candida albicans biofilms grown on titanium discs in vitro was investigated. As positive treatment controls, we used 0.1% chlorhexidine digluconate (CHX) and 0.6% sodium hypochlorite (NaOCl). The corresponding gas streams without plasma ignition served as negative treatment controls. The efficacy of the plasma treatment was determined evaluating the number of colony-forming units (CFU) recovered from titanium discs. The plasma treatment reduced the CFU significantly compared to chemical disinfectants. While 10 min CHX or NaOCl exposure led to a CFU log{sub 10} reduction factor of 1.5, the log{sub 10} reduction factor of DBD plasma was up to 5. In conclusion, the use of low-temperature plasma is a promising physical alternative to chemical antiseptics for dental practice.

  8. The low-current low-temperature plasma generators

    International Nuclear Information System (INIS)

    Dautov, G.Yu.

    2000-01-01

    In this article, the results of low-current gas-discharge plasma generator investigations carried out by a group of scientists from the Kazan' Aviation Institute are presented. When considered necessary, the results are compared with the data obtained by other authors. The basic configurations and theoretical calculation peculiarities of plasma generators are described. The electrical, thermal and energy characteristics of discharges in gas flows, as well as summarised empirical formulae and experimental data necessary for calculations and design of plasma devices are presented. (author)

  9. Polysilicon tft's fabricated by crystallization of a-si:h enhanced by hydrogen plasma

    International Nuclear Information System (INIS)

    Gallegos, O.; Garcia, R.; Estrada, M.; Cerdeira, A.; Leyva, A.

    2001-01-01

    Poly-silicon thin film transistors (TFTs) are widely applied in integrated LCD driving circuits and image sensors, because they have better characteristics than a-Si:H TFTs. Poly-silicon can deposited or obtained by crystallization of amorphous silicon layers after annealing above 900 oC. For the last years, research is been done in order to crystallize a- Si:H films at low temperature and time budget. In this work we present crystallization at 650 oC of intrinsic and doped a-Si:H layers after a hydrogen plasma annealing to enhanced the crystallization process. Intrinsic layers crystallized in 4-6 hours after annealing in hydrogen plasma, while doped layers crystallized for the same annealing times, independently of been or not annealed in hydrogen plasma. Layers were characterized by XRD and by resistivity measurements. Resistivity of n-type layers changed from 300 to 0.02 cm after crystallization. Resistivity of i-layers also decreased, but both values are very high and it is difficult to determine with precision its change. The high resistivity of the polycrystalline layers is determined by the small grain size. Poly-silicon TFTs were fabricated using the above procedure to crystallize the amorphous layers. The complete fabrication process is presented. Output characteristics are shown and compared to same characteristics for a-Si:H TFTs fabricated simultaneously with the exception of the crystallization process. TFTs' sensibility to light was also used to verify that crystallization took place

  10. Josephson plasma resonance in vortex filament state of high temperature superconductors

    International Nuclear Information System (INIS)

    Matsuda, Yuji; Gaifullin, M.B.

    1996-01-01

    High temperature superconductors have the crystalline structure in which two-dimensional CuO 2 planes are piled in layers, consequently, the anisotropy of electroconductivity arises, and this brings about stable and low energy Josephson plasma in superconducting state. Also as to the vortex filament state of high temperature superconductors, the effect of thermal fluctuation due to low dimensionality, short coherence length and high transition temperature becomes conspicuous. In reality, these plasma and vortex filament state are related closely. Light reflection and plasma edge in superconducting state, Josephson plasma resonance in the vortex filament state of BiO 2 Sr 2 CaCu 2 O 8+δ , the plasma vibration in Josephson junction, Josephson plasma in magnetic field, Josephson plasma in the liquid state of vortex filament, Josephson plasma in the solid state of vortex filament, and Josephson plasma in parallel magnetic field are reported. The Josephson plasma resonance is the experimental means for exploring vortex filament state from microscopic standpoint, and its development hereafter is expected. (K.I.)

  11. Spheroidization of transition metal carbides in low temperature plasma

    International Nuclear Information System (INIS)

    Klinskaya, N.A.; Koroleva, E.B.; Petrunichev, V.A.; Rybalko, O.F.; Solov'ev, P.V.; Ugol'nikova, T.A.

    1986-01-01

    Plasma process of preparation of titanium, tungsten and chromium carbide spherical powders with the main particle size 40-80 μm is considered. Spheroidization degree, granulometric and phase composition of the product are investigated

  12. Measurements of plasma temperature and electron density in laser ...

    Indian Academy of Sciences (India)

    of 6 ns focussed onto a copper solid sample in air at atmospheric pressure is studied spectroscopically. ... Pulsed laser-induced plasmas (LIPs) of metals and alloys formed at laser pulse ir- radiances near the .... fibre-based collection system.

  13. Formation and termination of High ion temperature mode in Heliotron/torsatron plasmas

    International Nuclear Information System (INIS)

    Ida, K.; Kondo, K.; Nagasaki, K.

    1997-01-01

    Physics of the formation and termination of High ion temperature mode (high T i mode) are studied by controlling density profiles and radial electric field. High ion temperature mode is observed for neutral beam heated plasmas in Heliotron/torsatron plasmas (Heliotron-E). This high T i mode plasma is characterized by a peaked ion temperature profile and is associated with a peaked electron density profile produced by neutral beam fueling with low wall recycling. This high T i mode is terminated by flattening the electron density caused by either gas puffing or second harmonic ECH (core density 'pump-out'). (author)

  14. A two-temperature chemical non-equilibrium modeling of DC arc plasma

    International Nuclear Information System (INIS)

    Qian Haiyang; Wu Bin

    2011-01-01

    To a better understanding of non-equilibrium characteristics of DC arc plasma,a two-dimensional axisymmetric two-temperature chemical non-equilibrium (2T-NCE) model is applied for direct current arc argon plasma generator with water-cooled constrictor at atmospheric pressure. The results show that the electron temperature and heavy particle temperature has a relationship under different working parameters, indicating that DC arc plasma has a strong non-equilibrium characteristic, and the variation is obvious. (authors)

  15. Characteristics of Ge-Sb-Te films prepared by cyclic pulsed plasma-enhanced chemical vapor deposition.

    Science.gov (United States)

    Suk, Kyung-Suk; Jung, Ha-Na; Woo, Hee-Gweon; Park, Don-Hee; Kim, Do-Heyoung

    2010-05-01

    Ge-Sb-Te (GST) thin films were deposited on TiN, SiO2, and Si substrates by cyclic-pulsed plasma-enhanced chemical vapor deposition (PECVD) using Ge{N(CH3)(C2H5)}, Sb(C3H7)3, Te(C3H7)3 as precursors in a vertical flow reactor. Plasma activated H2 was used as the reducing agent. The growth behavior was strongly dependent on the type of substrate. GST grew as a continuous film on TiN regardless of the substrate temperature. However, GST formed only small crystalline aggregates on Si and SiO2 substrates, not a continuous film, at substrate temperatures > or = 200 degrees C. The effects of the deposition temperature on the surface morphology, roughness, resistivity, crystallinity, and composition of the GST films were examined.

  16. A possibility of local measurements of ion temperature in a high-temperature plasma by laser induced ionization

    International Nuclear Information System (INIS)

    Kantor, M

    2012-01-01

    A new diagnostic for local measurements of ion temperature and drift velocity in fusion plasmas is proposed in the paper. The diagnostic is based on laser induced ionization of excited hydrogen and deuterium atoms from the levels which ionization energy less than the laser photon energy. A high intensive laser beam ionizes nearly all the excited atoms in the beam region resulting in a quench of spontaneous line emission of the appropriate optical transitions. The measurements of the quenching emission have been used in the past for local measurements of hydrogen atom density in tokamak plasma. The idea of the new diagnostic is spectral resolution of the quenching emission. The measured spectrum relates directly to the velocity distribution of the excited atoms. This distribution is strongly coupled to the distribution of the hydrogen atoms at the ground state. So, the spectral resolution of quenching emission is a way of local measurements of the temperature and drift velocity of hydrogen atoms in plasma. The temperature of hydrogen atoms is well coupled to the local ion temperature as long as the mean free path of the atoms is shorter than the ion gradient length in plasma. In this case the new diagnostic can provide local measurements of ion temperature in plasma. The paper considers technical capabilities of the diagnostic, physical restrictions of its application and interpretation of the measurements.

  17. Structural and chemical analysis of annealed plasma-enhanced atomic layer deposition aluminum nitride films

    Energy Technology Data Exchange (ETDEWEB)

    Broas, Mikael, E-mail: mikael.broas@aalto.fi; Vuorinen, Vesa [Department of Electrical Engineering and Automation, Aalto University, P.O. Box 13500, FIN-00076 Aalto, Espoo (Finland); Sippola, Perttu; Pyymaki Perros, Alexander; Lipsanen, Harri [Department of Micro- and Nanosciences, Aalto University, P.O. Box 13500, FIN-00076 Aalto, Espoo (Finland); Sajavaara, Timo [Department of Physics, University of Jyväskylä, P.O. Box 35, FIN-40014 Jyväskylä (Finland); Paulasto-Kröckel, Mervi [Department of Electrical Engineering and Automation, Aalto University. P.O. Box 13500, FIN-00076 Aalto, Espoo (Finland)

    2016-07-15

    Plasma-enhanced atomic layer deposition was utilized to grow aluminum nitride (AlN) films on Si from trimethylaluminum and N{sub 2}:H{sub 2} plasma at 200 °C. Thermal treatments were then applied on the films which caused changes in their chemical composition and nanostructure. These changes were observed to manifest in the refractive indices and densities of the films. The AlN films were identified to contain light element impurities, namely, H, C, and excess N due to nonideal precursor reactions. Oxygen contamination was also identified in the films. Many of the embedded impurities became volatile in the elevated annealing temperatures. Most notably, high amounts of H were observed to desorb from the AlN films. Furthermore, dinitrogen triple bonds were identified with infrared spectroscopy in the films. The triple bonds broke after annealing at 1000 °C for 1 h which likely caused enhanced hydrolysis of the films. The nanostructure of the films was identified to be amorphous in the as-deposited state and to become nanocrystalline after 1 h of annealing at 1000 °C.

  18. Measurement of thermal plasma jet temperature and velocity by laser light lineshape analysis

    International Nuclear Information System (INIS)

    Snyder, S.C.; Reynolds, L.D.

    1991-01-01

    Two important parameters of thermal plasma jets are kinetic or gas temperatures and flow velocity. Gas temperatures have been traditionally measured using emission spectroscopy, but this method depends on either the generally unrealistic assumption of the existence of local thermodynamic equilibrium (LTE) within the plasma, or the use of various non-LTE or partial LTE models to relate the intensity of the emission lines to the gas temperature. Plasma jet velocities have been measured using laser Doppler velocimetry on particles injected into the plasma. However, this method is intrusive and it is not known how well the particle velocities represent the gas velocity. Recently, plasma jet velocities have been measured from the Doppler shift of laser light scattered by the plasma. In this case, the Doppler shift was determined from the difference in the transmission profile of a high resolution monochromator between red shifted and blue shifted scattered light. A direct approach to measuring localized temperatures and velocities is afforded by high resolution scattered light lineshape measurements. The linewidth of laser light scattered by atoms and ions can be related to the kinetic temperature without LTE assumptions, while a shift in the peak position relative to the incident laser lineshape yields the gas velocity. We report in this paper work underway to measure gas temperatures and velocities in an argon thermal plasma jet using high resolution lineshape analysis of scattered laser light

  19. PIII Plasma Density Enhancement by a New DC Power Source

    International Nuclear Information System (INIS)

    Lopez-Callejas, R.; Godoy-Cabrera, O. G.; Granda-Gutierrez, E. E.; Piedad-Beneitez, A. de la; Munoz-Castro, A. E.; Valencia A, R.; Barocio, S. R.; Mercado-Cabrera, A.; Pena-Eguiluz, R.

    2006-01-01

    In practical terms, those plasmas produced by a DC voltage power supply do not attain densities above the 108 to 109 cm-3 band. Here we present a power supply, controlled in current and voltage, which has been successfully designed and constructed delivering plasma densities in the orders of 109 - 1010 cm-3. Its experimental performance test was conducted within one toroidal and one cylindrical chambers capable of 29 and 35 litres, respectively, using nitrogen gas. The DC plasma was characterized by a double electric probe. Several physical phenomena present in the PIII process have been keenly investigated including plasma sheath dynamics, interaction of plasma and surface, etc. In this paper we analyze the effect of the implantation voltage, plasma density and pulse time in the PIII average heating power and fluence density

  20. Liquid assisted plasma enhanced chemical vapour deposition with a non-thermal plasma jet at atmospheric pressure

    Czech Academy of Sciences Publication Activity Database

    Schäfer, J.; Fricke, K.; Mika, Filip; Pokorná, Zuzana; Zajíčková, L.; Foest, R.

    2017-01-01

    Roč. 630, MAY 30 (2017), s. 71-78 ISSN 0040-6090 R&D Projects: GA MŠk(CZ) LO1212; GA MŠk ED0017/01/01 Institutional support: RVO:68081731 Keywords : plasma jet * liquid assisted plasma enhanced chemical * vapour deposition * silicon oxide Subject RIV: JA - Electronics ; Optoelectronics, Electrical Engineering OBOR OECD: Coating and films Impact factor: 1.879, year: 2016

  1. Influence of Plasma Jet Temperature Profiles in Arc Discharge Methods of Carbon Nanotubes Synthesis.

    Science.gov (United States)

    Raniszewski, Grzegorz; Wiak, Slawomir; Pietrzak, Lukasz; Szymanski, Lukasz; Kolacinski, Zbigniew

    2017-02-23

    One of the most common methods of carbon nanotubes (CNTs) synthesis is application of an electric-arc plasma. However, the final product in the form of cathode deposit is composed of carbon nanotubes and a variety of carbon impurities. An assay of carbon nanotubes produced in arc discharge systems available on the market shows that commercial cathode deposits contain about 10% CNTs. Given that the quality of the final product depends on carbon-plasma jet parameters, it is possible to increase the yield of the synthesis by plasma jet control. Most of the carbon nanotubes are multiwall carbon nanotubes (MWCNTs). It was observed that the addition of catalysts significantly changes the plasma composition, effective ionization potential, the arc channel conductance, and in effect temperature of the arc and carbon elements flux. This paper focuses on the influence of metal components on plasma-jet forming containing carbon nanotubes cathode deposit. The plasma jet temperature control system is presented.

  2. Influence of Plasma Jet Temperature Profiles in Arc Discharge Methods of Carbon Nanotubes Synthesis

    Directory of Open Access Journals (Sweden)

    Grzegorz Raniszewski

    2017-02-01

    Full Text Available One of the most common methods of carbon nanotubes (CNTs synthesis is application of an electric-arc plasma. However, the final product in the form of cathode deposit is composed of carbon nanotubes and a variety of carbon impurities. An assay of carbon nanotubes produced in arc discharge systems available on the market shows that commercial cathode deposits contain about 10% CNTs. Given that the quality of the final product depends on carbon–plasma jet parameters, it is possible to increase the yield of the synthesis by plasma jet control. Most of the carbon nanotubes are multiwall carbon nanotubes (MWCNTs. It was observed that the addition of catalysts significantly changes the plasma composition, effective ionization potential, the arc channel conductance, and in effect temperature of the arc and carbon elements flux. This paper focuses on the influence of metal components on plasma-jet forming containing carbon nanotubes cathode deposit. The plasma jet temperature control system is presented.

  3. Current sheets with inhomogeneous plasma temperature: Effects of polarization electric field and 2D solutions

    International Nuclear Information System (INIS)

    Catapano, F.; Zimbardo, G.; Artemyev, A. V.; Vasko, I. Y.

    2015-01-01

    We develop current sheet models which allow to regulate the level of plasma temperature and density inhomogeneities across the sheet. These models generalize the classical Harris model via including two current-carrying plasma populations with different temperature and the background plasma not contributing to the current density. The parameters of these plasma populations allow regulating contributions of plasma density and temperature to the pressure balance. A brief comparison with spacecraft observations demonstrates the model applicability for describing the Earth magnetotail current sheet. We also develop a two dimensional (2D) generalization of the proposed model. The interesting effect found for 2D models is the nonmonotonous profile (along the current sheet) of the magnetic field component perpendicular to the current sheet. Possible applications of the model are discussed

  4. Current sheets with inhomogeneous plasma temperature: Effects of polarization electric field and 2D solutions

    Energy Technology Data Exchange (ETDEWEB)

    Catapano, F., E-mail: menacata3@gmail.com; Zimbardo, G. [Dipartimento di Fisica, Università della Calabria, Rende, Cosenza (Italy); Artemyev, A. V., E-mail: ante0226@gmail.com; Vasko, I. Y. [Space Research Institute, RAS, Moscow (Russian Federation)

    2015-09-15

    We develop current sheet models which allow to regulate the level of plasma temperature and density inhomogeneities across the sheet. These models generalize the classical Harris model via including two current-carrying plasma populations with different temperature and the background plasma not contributing to the current density. The parameters of these plasma populations allow regulating contributions of plasma density and temperature to the pressure balance. A brief comparison with spacecraft observations demonstrates the model applicability for describing the Earth magnetotail current sheet. We also develop a two dimensional (2D) generalization of the proposed model. The interesting effect found for 2D models is the nonmonotonous profile (along the current sheet) of the magnetic field component perpendicular to the current sheet. Possible applications of the model are discussed.

  5. Enhanced stimulated Raman scattering by femtosecond ultraviolet plasma grating in water

    Science.gov (United States)

    Liu, Fengjiang; Yuan, Shuai; He, Boqu; Nan, Junyi; Khan, Abdul Qayyum; Ding, Liang'en; Zeng, Heping

    2018-02-01

    Efficient forward stimulated Raman scattering (SRS) was observed along 400-nm femtosecond (fs) laser filaments in water. SRS conversion dominated over self-phase modulation induced continuum generation as the input pulse energy was above 4 μJ (˜30 Pcr), implying that plasma in the aqueous filamentation channel played an important role in compensating for the group velocity walk-off between the pump and Stokes pulses. By overlapping two synchronous fs 400-nm filaments to form plasma grating in water, significant enhancement of SRS conversion was observed. Such a SRS enhancement originated from the ultrahigh plasma density in the intersection region of the preformed plasma grating.

  6. Measurement of Temperature in the Steam Arcjet During Plasma Arc Cutting

    Czech Academy of Sciences Publication Activity Database

    Mašláni, Alan; Sember, Viktor; Stehrer, T.; Pauser, H.

    2013-01-01

    Roč. 33, č. 3 (2013), s. 593-604 ISSN 0272-4324 R&D Projects: GA ČR GAP205/11/2070 Institutional support: RVO:61389021 Keywords : Plasma arc cutting * Optical emission spectroscopy * Plasma temperature * Steam torch Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 1.599, year: 2013 http://link.springer.com/content/pdf/10.1007%2Fs11090-013-9443-y.pdf

  7. Electron temperature measurement in Maxwellian non-isothermal beam plasma of an ion thruster

    International Nuclear Information System (INIS)

    Zhang, Zun; Tang, Haibin; Kong, Mengdi; Zhang, Zhe; Ren, Junxue

    2015-01-01

    Published electron temperature profiles of the beam plasma from ion thrusters reveal many divergences both in magnitude and radial variation. In order to know exactly the radial distributions of electron temperature and understand the beam plasma characteristics, we applied five different experimental approaches to measure the spatial profiles of electron temperature and compared the agreement and disagreement of the electron temperature profiles obtained from these techniques. Experimental results show that the triple Langmuir probe and adiabatic poly-tropic law methods could provide more accurate space-resolved electron temperature of the beam plasma than other techniques. Radial electron temperature profiles indicate that the electrons in the beam plasma are non-isothermal, which is supported by a radial decrease (∼2 eV) of electron temperature as the plume plasma expands outward. Therefore, the adiabatic “poly-tropic law” is more appropriate than the isothermal “barometric law” to be used in electron temperature calculations. Moreover, the calculation results show that the electron temperature profiles derived from the “poly-tropic law” are in better agreement with the experimental data when the specific heat ratio (γ) lies in the range of 1.2-1.4 instead of 5/3

  8. Effects of rf power on electron density and temperature, neutral temperature, and Te fluctuations in an inductively coupled plasma

    International Nuclear Information System (INIS)

    Camparo, James; Fathi, Gilda

    2009-01-01

    Atomic clocks that fly on global-navigation satellites such as global positioning system (GPS) and Galileo employ light from low-temperature, inductively coupled plasmas (ICPs) for atomic signal generation and detection (i.e., alkali/noble-gas rf-discharge lamps). In this application, the performance of the atomic clock and the capabilities of the navigation system depend sensitively on the stability of the ICP's optical emission. In order to better understand the mechanisms that might lead to instability in these rf-discharge lamps, and hence the satellite atomic clocks, we studied the optical emission from a Rb/Xe ICP as a function of the rf power driving the plasma. Surprisingly, we found that the electron density in the plasma was essentially independent of increases in rf power above its nominal value (i.e., 'rf-power gain') and that the electron temperature was only a slowly varying function of rf-power gain. The primary effect of rf power was to increase the temperature of the neutrals in the plasma, which was manifested by an increase in Rb vapor density. Interestingly, we also found evidence for electron temperature fluctuations (i.e., fluctuations in the plasma's high-energy electron content). The variance of these fluctuations scaled inversely with the plasma's mean electron temperature and was consistent with a simple model that assumed that the total electron density in the discharge was independent of rf power. Taken as a whole, our results indicate that the electrons in alkali/noble-gas ICPs are little affected by slight changes in rf power and that the primary effect of such changes is to heat the plasma's neutral species.

  9. [Investigation on the gas temperature of a plasma jet at atmospheric pressure by emission spectrum].

    Science.gov (United States)

    Li, Xue-chen; Yuan, Ning; Jia, Peng-ying; Niu, Dong-ying

    2010-11-01

    A plasma jet of a dielectric barrier discharge in coaxial electrode was used to produce plasma plume in atmospheric pressure argon. Spatially and temporally resolved measurement was carried out by photomultiplier tubes. The light emission signals both from the dielectric barrier discharge and from the plasma plume were analyzed. Furthermore, emission spectrum from the plasma plume was collected by high-resolution optical spectrometer. The emission spectra of OH (A 2sigma + --> X2 II, 307.7-308.9 nm) and the first negative band of N2+ (B2 sigma u+ --> X2 IIg+, 390-391.6 nm) were used to estimate the rotational temperature of the plasma plume by fitting the experimental spectra to the simulated spectra. The rotational temperature obtained is about 443 K by fitting the emission spectrum from the OH, and that from the first negative band of N2+ is about 450 K. The rotational temperatures obtained by the two method are consistent within 5% error band. The gas temperature of the plasma plume at atmospheric pressure was obtained because rotational temperature equals to gas temperature approximately in gas discharge at atmospheric pressure. Results show that gas temperature increases with increasing the applied voltage.

  10. Low temperature synthesis of silicon quantum dots with plasma chemistry control in dual frequency non-thermal plasmas.

    Science.gov (United States)

    Sahu, Bibhuti Bhusan; Yin, Yongyi; Han, Jeon Geon; Shiratani, Masaharu

    2016-06-21

    The advanced materials process by non-thermal plasmas with a high plasma density allows the synthesis of small-to-big sized Si quantum dots by combining low-temperature deposition with superior crystalline quality in the background of an amorphous hydrogenated silicon nitride matrix. Here, we make quantum dot thin films in a reactive mixture of ammonia/silane/hydrogen utilizing dual-frequency capacitively coupled plasmas with high atomic hydrogen and nitrogen radical densities. Systematic data analysis using different film and plasma characterization tools reveals that the quantum dots with different sizes exhibit size dependent film properties, which are sensitively dependent on plasma characteristics. These films exhibit intense photoluminescence in the visible range with violet to orange colors and with narrow to broad widths (∼0.3-0.9 eV). The observed luminescence behavior can come from the quantum confinement effect, quasi-direct band-to-band recombination, and variation of atomic hydrogen and nitrogen radicals in the film growth network. The high luminescence yields in the visible range of the spectrum and size-tunable low-temperature synthesis with plasma and radical control make these quantum dot films good candidates for light emitting applications.

  11. Determination of plasma temperature and electron density in river sediment plasma using calibration-free laser-induced breakdown spectroscopy

    International Nuclear Information System (INIS)

    Austria, Elmer S. Jr.; Lamorena-Lim, Rheo B.

    2015-01-01

    Calibration-free laser-induced breakdown spectroscopy (CF-LIBS) technique is an approach used to quantitatively measure elemental composition of samples without the use of standard reference materials (SRMs). Due to the unavailability of most SRMs for specific samples, the CF-LIBS approach is steadily becoming more prevalent. CF-LIBS also minimizes interferences from the sample matrix by accounting spectral line intensifies of different elements. The first part of the CF-LIBS algorithm is the calculation of plasma temperature and electron density of the sample while the second part deals with the self-absorption correction and quantitative elemental analysis. In this study, the precursor parameters for the algorithm - plasma temperature and electron density - were measured through the neutral atom and ion line emissions of Fe and Cu in the time window of 0.1 to 10 μs. Plasma from river sediment samples were produced by a 1064 nm nanosecond pulsed Nd:YAG laser at atmospheric pressure. The plasma temperature and electron density were calculated from the Boltzmann plot and Saha-Boltzmann equation methods, respectively. These precursor parameters can be used in calculating the time window wherein the plasma is optically thin at local thermodynamic equilibrium (LTE) and for quantitative multi-elemental analysis. (author)

  12. Development of a laser-induced plasma probe to measure gas phase plasma signals at high pressures and temperatures

    International Nuclear Information System (INIS)

    Gounder, J.D.; Kutne, P.; Meier, W.

    2012-01-01

    The ability of laser induced breakdown spectroscopy (LIBS) technique for on line simultaneous measurement of elemental concentrations has led to its application in a wide number of processes. The simplicity of the technique allows its application to harsh environments such as present in boilers, furnaces and gasifiers. This paper presents the design of a probe using a custom optic which transforms a round beam into a ring (Donut) beam, which is used for forming a plasma in an atmosphere of nitrogen at high pressure (20 bar) and temperature (200 °C). The LIBS experiments were performed using a high pressure cell to characterize and test the effectiveness of the donut beam transmitted through the LIBS probe and collect plasma signal in back scatter mode. The first tests used the second harmonic of a Nd:YAG laser, pulse width 7 ns, to form a plasma in nitrogen gas at five different pressures (1, 5, 10, 15 and 20 bar) and three different gas temperatures (25, 100 and 200 °C). The uniqueness of this probe is the custom made optic used for reshaping the round laser beam into a ring (Donut) shaped laser beam, which is fed into the probe and focused to form a plasma at the measurement point. The plasma signal is collected and collimated using the laser focusing lens and is reflected from the laser beam axis onto an achromatic lens by a high reflection mirror mounted in the center section of the donut laser beam. The effect of gas pressure and temperature on N(I) lines in the high pressure cell experiment shows that the line intensity decreases with pressure and increases with temperature. Mean plasma temperature was calculated using the ratios of N(I) line intensities ranging from 7400 K to 8900 K at 1 bar and 2400 K to 3200 K at 20 bar for the three different gas temperatures. The results show that as a proof of principle the donut beam optics in combination with the LIBS probe can be used for performing extensive LIBS measurements in well controlled laboratory

  13. Development of a laser-induced plasma probe to measure gas phase plasma signals at high pressures and temperatures

    Energy Technology Data Exchange (ETDEWEB)

    Gounder, J.D., E-mail: James.Gounder@dlr.de; Kutne, P.; Meier, W.

    2012-08-15

    The ability of laser induced breakdown spectroscopy (LIBS) technique for on line simultaneous measurement of elemental concentrations has led to its application in a wide number of processes. The simplicity of the technique allows its application to harsh environments such as present in boilers, furnaces and gasifiers. This paper presents the design of a probe using a custom optic which transforms a round beam into a ring (Donut) beam, which is used for forming a plasma in an atmosphere of nitrogen at high pressure (20 bar) and temperature (200 Degree-Sign C). The LIBS experiments were performed using a high pressure cell to characterize and test the effectiveness of the donut beam transmitted through the LIBS probe and collect plasma signal in back scatter mode. The first tests used the second harmonic of a Nd:YAG laser, pulse width 7 ns, to form a plasma in nitrogen gas at five different pressures (1, 5, 10, 15 and 20 bar) and three different gas temperatures (25, 100 and 200 Degree-Sign C). The uniqueness of this probe is the custom made optic used for reshaping the round laser beam into a ring (Donut) shaped laser beam, which is fed into the probe and focused to form a plasma at the measurement point. The plasma signal is collected and collimated using the laser focusing lens and is reflected from the laser beam axis onto an achromatic lens by a high reflection mirror mounted in the center section of the donut laser beam. The effect of gas pressure and temperature on N(I) lines in the high pressure cell experiment shows that the line intensity decreases with pressure and increases with temperature. Mean plasma temperature was calculated using the ratios of N(I) line intensities ranging from 7400 K to 8900 K at 1 bar and 2400 K to 3200 K at 20 bar for the three different gas temperatures. The results show that as a proof of principle the donut beam optics in combination with the LIBS probe can be used for performing extensive LIBS measurements in well controlled

  14. Surface modification of chromatography adsorbents by low temperature low pressure plasma

    DEFF Research Database (Denmark)

    Arpanaei, Ayyoob; Winther-Jensen, Bjørn; Theodosiou, E.

    2010-01-01

    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 ...

  15. Density and temperature diagnostics of a Ne-like germanium plasma created by laser

    International Nuclear Information System (INIS)

    Berthier, E.; Bourgade, J.L.; Combis, P.; Jacquemot, S.; Le Breton, J.P.; Louis-Jacquet, M.; Naccache, D.; Nail, M.; Peyrusse, O.

    1987-01-01

    In the framework of X-ray laser studies, experiments on Ne-like Ge plasma have been performed by laser irradiation at λ = 1.053 μm. Amplification in lasing transitions has been observed by varying the plasma length. Theoretical calculations of excited level population allow us to determine density and temperature from line intensity ratios

  16. Temperature dynamics and velocity scaling laws for interchange driven, warm ion plasma filaments

    DEFF Research Database (Denmark)

    Olsen, Jeppe Miki Busk; Madsen, Jens; Nielsen, Anders Henry

    2016-01-01

    The influence of electron and ion temperature dynamics on the radial convection of isolated structures in magnetically confined plasmas is investigated by means of numerical simulations. It is demonstrated that the maximum radial velocity of these plasma blobs roughly follows the inertial velocity...

  17. Electron density and temperature determination in a Tokamak plasma using light scattering

    International Nuclear Information System (INIS)

    Perez-Navarro Gomez, A.; Zurro Hernandez, B.

    1976-01-01

    A theoretical foundation review for light scattering by plasmas is presented. Furthemore, a review of the experimental methods for electron density and temperature measurements, with spatial and time resolution, is included in a Tokamak plasma using spectral analysis of the scattered radiation. (author) [es

  18. Electron density and temperature determination in a Tokamak plasma using light scattering

    International Nuclear Information System (INIS)

    Perez-Navarro Gomerz, A.; Zurro Hernandez, B.

    1976-01-01

    A theoretical foundation review for light scattering by plasmas is presented. Furthermore, we have included a review of the experimental methods for electron density and temperature measurements, with spatial and time resolution, in a Tokamak plasma using spectral analysis of the scattered radiation. (Author) 13 refs

  19. Time-resolved tomographic measurements of temperatures in a thermal plasma jet

    Czech Academy of Sciences Publication Activity Database

    Hlína, Jan; Šonský, Jiří

    2010-01-01

    Roč. 43, č. 5 (2010), s. 1-9 ISSN 0022-3727 Institutional research plan: CEZ:AV0Z20570509 Keywords : thermal plasma jet * optical diagnostics * temperature distribution Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.105, year: 2010

  20. Improving Erosion Resistance of Plasma-Sprayed Ceramic Coatings by Elevating the Deposition Temperature Based on the Critical Bonding Temperature

    Science.gov (United States)

    Yao, Shu-Wei; Yang, Guan-Jun; Li, Cheng-Xin; Li, Chang-Jiu

    2018-01-01

    Interlamellar bonding within plasma-sprayed coatings is one of the most important factors dominating the properties and performance of coatings. The interface bonding between lamellae significantly influences the erosion behavior of plasma-sprayed ceramic coatings. In this study, TiO2 and Al2O3 coatings with different microstructures were deposited at different deposition temperatures based on the critical bonding temperature concept. The erosion behavior of ceramic coatings was investigated. It was revealed that the coatings prepared at room temperature exhibit a typical lamellar structure with numerous unbonded interfaces, whereas the coatings deposited at the temperature above the critical bonding temperature present a dense structure with well-bonded interfaces. The erosion rate decreases sharply with the improvement of interlamellar bonding when the deposition temperature increases to the critical bonding temperature. In addition, the erosion mechanisms of ceramic coatings were examined. The unbonded interfaces in the conventional coatings act as pre-cracks accelerating the erosion of coatings. Thus, controlling interlamellar bonding formation based on the critical bonding temperature is an effective approach to improve the erosion resistance of plasma-sprayed ceramic coatings.

  1. Electron temperature measurement by a helium line intensity ratio method in helicon plasmas

    International Nuclear Information System (INIS)

    Boivin, R.F.; Kline, J.L.; Scime, E.E.

    2001-01-01

    Electron temperature measurements in helicon plasmas are difficult. The presence of intense rf fields in the plasma complicates the interpretation of Langmuir probe measurements. Furthermore, the non-negligible ion temperature in the plasma considerably shortens the lifetime of conventional Langmuir probes. A spectroscopic technique based on the relative intensities of neutral helium lines is used to measure the electron temperature in the HELIX (Hot hELicon eXperiment) plasma [P. A. Keiter et al., Phys. Plasmas 4, 2741 (1997)]. This nonintrusive diagnostic is based on the fact that electron impact excitation rate coefficients for helium singlet and triplet states differ as a function of the electron temperature. The different aspects related to the validity of this technique to measure the electron temperature in rf generated plasmas are discussed in this paper. At low plasma density (n e ≤10 11 cm -3 ), this diagnostic is believed to be very reliable since the population of the emitting level can be easily estimated with reasonable accuracy by assuming that all excitation originates from the ground state (steady-state corona model). At higher density, secondary processes (excitation transfer, excitation from metastable, cascading) become more important and a more complex collisional radiative model must be used to predict the electron temperature. In this work, different helium transitions are examined and a suitable transition pair is identified. For an electron temperature of 10 eV, the line ratio is measured as a function of plasma density and compared to values predicted by models. The measured line ratio function is in good agreement with theory and the data suggest that the excitation transfer is the dominant secondary process in high-density plasmas

  2. Photoionization capable, extreme and vacuum ultraviolet emission in developing low temperature plasmas in air

    NARCIS (Netherlands)

    Stephens, J.; Fierro, A.; Beeson, S.; Laity, G.; Trienekens, D.; Joshi, R.P.; Dickens, J.; Neuber, A.

    2016-01-01

    Experimental observation of photoionization capable extreme ultraviolet and vacuum ultraviolet emission from nanosecond timescale, developing low temperature plasmas (i.e. streamer discharges) in atmospheric air is presented. Applying short high voltage pulses enabled the observation of the onset of

  3. Evolution of the electron temperature profile of ohmically heated plasmas in TFTR

    International Nuclear Information System (INIS)

    Taylor, G.; Efthimion, P.C.; Arunasalam, V.

    1985-08-01

    Blackbody electron cyclotron emission was used to ascertain and study the evolution and behavior of the electron temperature profile in ohmically heated plasmas in the Tokamak Fusion Test Reactor (TFTR). The emission was measured with absolutely calibrated millimeter wavelength radiometers. The temperature profile normalized to the central temperature and minor radius is observed to broaden substantially with decreasing limiter safety factor q/sub a/, and is insensitive to the plasma minor radius. Sawtooth activity was seen in the core of most TFTR discharges and appeared to be associated with a flattening of the electron temperature profile within the plasma core where q less than or equal to 1. Two types of sawtooth behavior were identified in large TFTR plasmas (minor radius, a less than or equal to 0.8 m) : a typically 35 to 40 msec period ''normal'' sawtooth, and a ''compound'' sawtooth with 70 to 80 msec period

  4. Enhanced low-temperature oxidation of zirconium alloys under irradiation

    International Nuclear Information System (INIS)

    Cox, B.; Fidleris, V.

    1989-01-01

    The linear growth of relatively thick (>300 nm) interference-colored oxide films on zirconium alloy specimens exposed in the Advanced Test Reactor (ATR) coolant at ≤55 o C was unexpected. Initial ideas were that this was a photoconduction effect. Experiments to study photoconduction in thin anodic zirconium oxide (ZrO 2 ) films in the laboratory were initiated to provide background data. It was found that, in the laboratory, provided a high electric field was maintained across the oxide during ultraviolet (UV) irradiation, enhanced growth of oxide occurred in the irradiated area. Similarly enhanced growth could be obtained on thin thermally formed oxide films that were immersed in an electrolyte with a high electric field superimposed. This enhanced growth was found to be caused by the development of porosity in the barrier oxide layer by an enhanced local dissolution and reprecipitation process during UV irradiation. Similar porosity was observed in the oxide films on the ATR specimens. Since it is not thought that a high electric field could have been present in this instance, localized dissolution of fast-neutron primary recoil tracks may be the operative mechanism. In all instances, the specimens attempt to maintain the normal barrier-layer oxide thickness, which causes the additional oxide growth. Similar mechanisms may have operated during the formation of thick loosely adherent, porous oxides in homogeneous reactor solutions under irradiation, and may be the cause of enhanced oxidation of zirconium alloys in high-temperature water-cooled reactors in some water chemistries. (author)

  5. Low temperature synthesis of ternary metal phosphides using plasma for asymmetric supercapacitors

    KAUST Repository

    Liang, Hanfeng

    2017-04-06

    We report a versatile route for the preparation of metal phosphides using PH plasma for supercapacitor applications. The high reactivity of plasma allows rapid and low temperature conversion of hydroxides into monometallic, bimetallic, or even more complex nanostructured phosphides. These same phosphides are much more difficult to synthesize by conventional methods. Further, we present a general strategy for significantly enhancing the electrochemical performance of monometallic phosphides by substituting extrinsic metal atoms. Using NiCoP as a demonstration, we show that the Co substitution into NiP not only effectively alters the electronic structure and improves the intrinsic reactivity and electrical conductivity, but also stabilizes Ni species when used as supercapacitor electrode materials. As a result, the NiCoP nanosheet electrodes achieve high electrochemical activity and good stability in 1 M KOH electrolyte. More importantly, our assembled NiCoP nanoplates//graphene films asymmetric supercapacitor devices can deliver a high energy density of 32.9 Wh kg at a power density of 1301 W kg, along with outstanding cycling performance (83% capacity retention after 5000 cycles at 20 A g). This activity outperforms most of the NiCo-based materials and renders the NiCoP nanoplates a promising candidate for capacitive storage devices.

  6. Computation and measurement of a plasma temperature using the emission lines of copper

    International Nuclear Information System (INIS)

    Sassi, M.; Pierre, L.; Benard, J.; Cahen, C.

    1994-01-01

    The use of copper emission lines for temperature measurement in plasma environments is presented. The article features the problems encountered with such a measurement method when used in a stationary and a non-stationary plasma. In the first case, we were concerned with the temperature measurements in the jet of a 2 MW industrial plasma torche. The plasma was stationary and the measurement geometry allowed the use of the Abel inversion method to recover the temperature profiles in the plasma jet. The limitations of the measurement method on the jet boundaries as well as the cooling of the plasma by entrainement of cold air are discussed. In the second case, a non-stationary plasma in a 1.4 MW electric furnace was studied. This study allowed to feature the role of the detector dynamics as related to the dynamics of the observed medium. The obtained measurements show only a probable temperature in the immediate proximity of the arc. Finally, we conclude on the validity of copper as a tracer and the use of spontaneous emission spectroscopy, and easy method to implement, compared to other sophisticated temperature measurement methods. (orig.)

  7. Low-temperature plasma-induced antiproliferative effects on multi-cellular tumor spheroids

    International Nuclear Information System (INIS)

    Plewa, Joseph-Marie; Yousfi, Mohammed; Eichwald, Olivier; Merbahi, Nofel; Frongia, Céline; Ducommun, Bernard; Lobjois, Valérie

    2014-01-01

    Biomedical applications of low-temperature plasmas are of growing interest, especially in the field of plasma-induced anti-tumor effects. The present work is aimed at investigating the regionalized antiproliferative effects of low-temperature plasmas on a multicellular tumor spheroid (MCTS), a model that mimics the 3D organization and regionalization of a microtumor region. We report that a low-temperature plasma jet, using helium flow in open air, inhibits HCT116 colon carcinoma MCTS growth in a dose-dependent manner. This growth inhibition is associated with the loss of Ki67, and the regionalized accumulation of DNA damage detected by histone H2AX phosphorylation. This regionalized genotoxic effect leads to massive cell death and loss of the MCTS proliferative region. The use of reactive oxygen species (ROS), scavenger N-acetyl cysteine (NAC) and plasma-conditioned media demonstrate that the ROS generated in the media after exposure to low-temperature plasma play a major role in these observed effects. These findings strengthen the interest in the use of MCTS for the evaluation of antiproliferative strategies, and open new perspectives for studies dedicated to demonstrate the potential of low-temperature plasma in cancer therapy

  8. Low-temperature plasma-induced antiproliferative effects on multi-cellular tumor spheroids

    Science.gov (United States)

    Plewa, Joseph-Marie; Yousfi, Mohammed; Frongia, Céline; Eichwald, Olivier; Ducommun, Bernard; Merbahi, Nofel; Lobjois, Valérie

    2014-04-01

    Biomedical applications of low-temperature plasmas are of growing interest, especially in the field of plasma-induced anti-tumor effects. The present work is aimed at investigating the regionalized antiproliferative effects of low-temperature plasmas on a multicellular tumor spheroid (MCTS), a model that mimics the 3D organization and regionalization of a microtumor region. We report that a low-temperature plasma jet, using helium flow in open air, inhibits HCT116 colon carcinoma MCTS growth in a dose-dependent manner. This growth inhibition is associated with the loss of Ki67, and the regionalized accumulation of DNA damage detected by histone H2AX phosphorylation. This regionalized genotoxic effect leads to massive cell death and loss of the MCTS proliferative region. The use of reactive oxygen species (ROS), scavenger N-acetyl cysteine (NAC) and plasma-conditioned media demonstrate that the ROS generated in the media after exposure to low-temperature plasma play a major role in these observed effects. These findings strengthen the interest in the use of MCTS for the evaluation of antiproliferative strategies, and open new perspectives for studies dedicated to demonstrate the potential of low-temperature plasma in cancer therapy.

  9. Ion temperature in plasmas with intrinsic Alfven waves

    International Nuclear Information System (INIS)

    Wu, C. S.; Yoon, P. H.; Wang, C. B.

    2014-01-01

    This Brief Communication clarifies the physics of non-resonant heating of protons by low-frequency Alfvenic turbulence. On the basis of general definition for wave energy density in plasmas, it is shown that the wave magnetic field energy is equivalent to the kinetic energy density of the ions, whose motion is induced by the wave magnetic field, thus providing a self-consistent description of the non-resonant heating by Alfvenic turbulence. Although the study is motivated by the research on the solar corona, the present discussion is only concerned with the plasma physics of the heating process

  10. Fabrication of aligned carbon nanotubes on Cu catalyst by dc plasma-enhanced catalytic decomposition

    Energy Technology Data Exchange (ETDEWEB)

    Zhang Zhejuan [Department of Physics, Engineering Research Center for Nanophotonics and Advanced Instrument, East China Normal University, North Zhongshan Road 3663, 200062 Shanghai (China); Shakerzadeh, Maziar; Tay, Beng Kang; Li Xiaocheng; Tan Chongwei [School of Electrical and Electronic Engineering, Nanyang Technological University, Nanyang Avenue 50, 639798 Singapore (Singapore); Lin Lifeng; Guo Pingsheng; Feng Tao [Department of Physics, Engineering Research Center for Nanophotonics and Advanced Instrument, East China Normal University, North Zhongshan Road 3663, 200062 Shanghai (China); Sun Zhuo, E-mail: zsun@phy.ecnu.edu.cn [Department of Physics, Engineering Research Center for Nanophotonics and Advanced Instrument, East China Normal University, North Zhongshan Road 3663, 200062 Shanghai (China)

    2009-04-01

    Aligned multi-walled carbon nanotubes (ACNTs) are deposited using copper (Cu) catalyst on Chromium (Cr)-coated substrate by plasma-enhanced chemical vapor deposition at temperature of 700 deg. C. Acetylene gas has been used as the carbon source while ammonia is used for diluting and etching. The thicknesses of Cu films on Cr-coated Si (100) substrates are controlled by deposition time of magnetron sputtering. The growth behaviors and quality of ACNTs are investigated by scanning electron microscopy (SEM) and transmission electron microscopy. The different performance of ACNTs on various Cu films is explained by referring to the graphitic order as detected by Raman spectroscopy. The results indicate that the ACNTs are formed in tip-growth model where Cu is used as a novel catalyst, and the thickness of Cu films is responsible to the diameter and quality of synthesized CNTs.

  11. Stress hysteresis and mechanical properties of plasma-enhanced chemical vapor deposited dielectric films

    Science.gov (United States)

    Thurn, Jeremy; Cook, Robert F.; Kamarajugadda, Mallika; Bozeman, Steven P.; Stearns, Laura C.

    2004-02-01

    A comprehensive survey is described of the responses of three plasma-enhanced chemical vapor deposited dielectric film systems to thermal cycling and indentation contact. All three films—silicon oxide, silicon nitride, and silicon oxy-nitride—exhibited significant nonequilibrium permanent changes in film stress on thermal cycling or annealing. The linear relationship between stress and temperature changed after the films were annealed at 300 °C, representing a structural alteration in the film reflecting a change in coefficient of thermal expansion or biaxial modulus. A double-substrate method was used to deduce both thermoelastic properties before and after the anneal of selected films and the results were compared with the modulus deconvoluted from small-scale depth-sensing indentation experiments (nanoindentation). Rutherford backscattering spectrometry and hydrogen forward scattering were used to deduce the composition of the films and it was found that all the films contained significant amounts of hydrogen.

  12. Plasma-enhanced growth, composition, and refractive index of silicon oxy-nitride films

    DEFF Research Database (Denmark)

    Mattsson, Kent Erik

    1995-01-01

    Secondary ion mass spectrometry and refractive index measurements have been carried out on silicon oxy-nitride produced by plasma-enhanced chemical vapor deposition (PECVD). Nitrous oxide and ammonia were added to a constant flow of 2% silane in nitrogen, to produce oxy-nitride films with atomic...... nitrogen concentrations between 2 and 10 at. %. A simple atomic valence model is found to describe both the measured atomic concentrations and published material compositions for silicon oxy-nitride produced by PECVD. A relation between the Si–N bond concentration and the refractive index is found......-product. A model, that combine the chemical net reaction and the stoichiometric rules, is found to agree with measured deposition rates for given material compositions. Effects of annealing in a nitrogen atmosphere has been investigated for the 400 °C– 1100 °C temperature range. It is observed that PECVD oxy...

  13. Electrical description of a magnetic pole enhanced inductively coupled plasma source: Refinement of the transformer model by reverse electromagnetic modeling

    International Nuclear Information System (INIS)

    Meziani, T.; Colpo, P.; Rossi, F.

    2006-01-01

    The magnetic pole enhanced inductively coupled source (MaPE-ICP) is an innovative low-pressure plasma source that allows for high plasma density and high plasma uniformity, as well as large-area plasma generation. This article presents an electrical characterization of this source, and the experimental measurements are compared to the results obtained after modeling the source by the equivalent circuit of the transformer. In particular, the method applied consists in performing a reverse electromagnetic modeling of the source by providing the measured plasma parameters such as plasma density and electron temperature as an input, and computing the total impedance seen at the primary of the transformer. The impedance results given by the model are compared to the experimental results. This approach allows for a more comprehensive refinement of the electrical model in order to obtain a better fitting of the results. The electrical characteristics of the system, and in particular the total impedance, were measured at the inductive coil antenna (primary of the transformer). The source was modeled electrically by a finite element method, treating the plasma as a conductive load and taking into account the complex plasma conductivity, the value of which was calculated from the electron density and electron temperature measurements carried out previously. The electrical characterization of the inductive excitation source itself versus frequency showed that the source cannot be treated as purely inductive and that the effect of parasitic capacitances must be taken into account in the model. Finally, considerations on the effect of the magnetic core addition on the capacitive component of the coupling are made

  14. X radiation diagnostics of high-temperature laser plasma

    International Nuclear Information System (INIS)

    Marsak, Z.; Bryknar, Z.; Legova, S.; Pina, L.

    1980-01-01

    Main aspects of X-ray emission from plasma heated by a pulsed laser and methods of its detection are presented, especially using a pinhole camera and a multichannel spectrometer with p-i-n diodes and Be-filters for measurement in the energy range 0.5 keV to 3 keV. (author)

  15. Accurate methods for calculating atomic processes in high temperature plasmas

    International Nuclear Information System (INIS)

    Keady, J.J.; Abdallah, J.A. Jr.; Clark, R.E.H.

    1992-01-01

    A technique for computing monochromatic X-ray absorption is described and compared to experimental data. Calculations of power loss from carbon plasmas with comprehensive new datasets confirm that the direct inclusion of metastable states can noticeably decrease the calculated power loss

  16. Slide-away distributions and relevant collective modes in high-temperature plasmas

    International Nuclear Information System (INIS)

    Coppi, B.; Pegoraro, F.; Pozzoli, R.; Rewoldt, G.

    1976-01-01

    The evolution of the electron distribution function, when an electric field that is not too small in comparison with the critical electron runaway field is applied along the confining magnetic field of a high temperature plasma, is analysed. In the regimes considered, a finite fraction of the electron population has magnetically trapped orbits, and is not appreciably affected by the applied electric field, while the distribution of circulating electrons tends to ''slide away'' as a whole. Then the Spitzer-Haerm model for the current-carrying electron distribution is inadequate, and the role that collective modes, in particular current-driven microinstabilities, and collisions can play in producing a stationary electron distribution is analysed. Modes at the ion plasma frequency, ωsub(pi), that are driven by the positive slope of the current-carrying electron distribution, can be excited, when the average electron drift velocity is a finite fraction of the electron thermal velocity, and transfer transverse energy to the main body of the electron distribution. These features are consistent with the experimental observations performed on the Alcator device. Modes at the ''reduced'' electron plasma frequency (ksub(parallel)/k)ωsub(pe) can also be excited both in connection with the modes at wsub(pi) and independently. Modes at the electron gyrofrequency Ωsub(e) associated with the loss-cone feature that the electron distribution tends to develop are considered, among others, as a factor for the strongly enhanced electron cyclotron emission experimentally observed in regimes where non-thermal electron distributions have been realized. (author)

  17. Enhanced resonant second harmonic generation in plasma based on density transition

    Directory of Open Access Journals (Sweden)

    Kant Niti

    2015-06-01

    Full Text Available Resonant second harmonic generation of a relativistic self-focusing laser in plasma with density ramp profile has been investigated. A high intense Gaussian laser beam generates resonant second harmonic beam in plasma with density ramp profile. The second harmonic undergoes periodic focusing in the plasma channel created by the fundamental wave. The normalized second harmonic amplitude varies periodically with distance and attains maximum value in the focal region. Enhancement in the second harmonic amplitude on account of relativistic self-focusing of laser based on plasma density transition is seen. Plasma density ramp plays an important role to make self-focusing stronger which leads to enhance the second harmonic generation in plasma.

  18. Compression enhancement by current stepping in a multicascade liner gas-puff Z-pinch plasma

    Energy Technology Data Exchange (ETDEWEB)

    Khattak, N A D [Department of Physics, Gomal Unversity, D I Khan (Pakistan); Ahmad, Zahoor; Murtaza, G [National Tokamak Fusion Program, PAEC, Islamabad (Pakistan); Zakaullah, M [Department of Physics, Quaid-i-Azam University, Islamabad 45320 (Pakistan)], E-mail: ktk_nad@yahoo.com

    2008-04-15

    Plasma dynamics of a liner consisting of two or three annular cascade gas-puffs with entrained axial magnetic field is studied using the modified snow-plow model. The current stepping technique (Les 1984 J. Phys. D: Appl. Phys. 17 733) is employed to enhance compression of the imploding plasma. A small-diameter low-voltage-driven system of imploding plasma is considered in order to work out the possibility of the highest gain, in terms of plasma parameters and radiation yield with a relatively simple and compact system. Our numerical results demonstrate that current stepping enhances the plasma compression, yielding high values of the plasma parameters and compressed magnetic field B{sub z} (in magnitudes), if the switching time for the additional current is properly synchronized.

  19. Compression enhancement by current stepping in a multicascade liner gas-puff Z-pinch plasma

    International Nuclear Information System (INIS)

    Khattak, N A D; Ahmad, Zahoor; Murtaza, G; Zakaullah, M

    2008-01-01

    Plasma dynamics of a liner consisting of two or three annular cascade gas-puffs with entrained axial magnetic field is studied using the modified snow-plow model. The current stepping technique (Les 1984 J. Phys. D: Appl. Phys. 17 733) is employed to enhance compression of the imploding plasma. A small-diameter low-voltage-driven system of imploding plasma is considered in order to work out the possibility of the highest gain, in terms of plasma parameters and radiation yield with a relatively simple and compact system. Our numerical results demonstrate that current stepping enhances the plasma compression, yielding high values of the plasma parameters and compressed magnetic field B z (in magnitudes), if the switching time for the additional current is properly synchronized

  20. Electric sheath and presheath in a collisionless, finite ion temperature plasma

    International Nuclear Information System (INIS)

    Emmert, G.A.; Wieland, R.M.; Mense, A.T.; Davidson, J.N.

    1980-01-01

    The plasma-sheath equation for a collisionless plasma with arbitrary ion temperature in plane geometry is formulated. Outside the sheath, this equation is approximated by the plasma equation, for which an analytic solution for the electrostatic potential is obtained. In addition, the ion distribution function, the wall potential, and the ion energy and particle flux into the sheath are explicitly calculated. The plasma-sheath equation is also solved numerically with no approximation of the Debye length. The numerical results compare well with the analytical results when the Debye length is small

  1. Targets on the basis of ferrites and high-temperature superconductors for ion-plasma sputtering

    International Nuclear Information System (INIS)

    Lepeshev, A.A.; Saunin, V.N.; Telegin, S.V.; Polyakova, K.P.; Seredkin, V.A.; Pol'skij, A.I.

    2000-01-01

    Paper describes a method to produce targets for ion-plasma sputtering using plasma splaying of the appropriate powders on a cooled metal basis. Application of the plasma process was demonstrated to enable to produce complex shaped targets under the controlled atmosphere on the basis of ceramic materials ensuring their high composition homogeneity, as well as, reliable mechanical and thermal contact of the resultant coating with the base. One carried out experiments in ion-plasma sputtering of targets to prepare ferrite polycrystalline films to be used in magnetooptics and to prepare high-temperature superconductor epitaxial films [ru

  2. Interpretation of fast measurements of plasma potential, temperature and density in SOL of ASDEX Upgrade

    DEFF Research Database (Denmark)

    Horacek, J.; Adamek, J.; Müller, H.W.

    2010-01-01

    This paper focuses on interpretation of fast (1 µs) and local (2–4 mm) measurements of plasma density, potential and electron temperature in the edge plasma of tokamak ASDEX Upgrade. Steady-state radial profiles demonstrate the credibility of the ball-pen probe. We demonstrate that floating...... potential fluctuations measured by a Langmuir probe are dominated by plasma electron temperature rather than potential. Spatial and temporal scales are found consistent with expectations based on interchange-driven turbulence. Conditionally averaged signals found for both potential and density are also...

  3. Temperature determination from a real plasma from line self-reversal

    International Nuclear Information System (INIS)

    Salakhov, M.K.; Fishman, I.S.

    1981-01-01

    The coefficient Z = M/sub infinity/Y/sub infinity/ is determined on the basis of the actual structure of a plasma (the M/sub infinity/ and Y/sub infinity/ coefficients in Bartels's theory). The absorption and emission spectra are utilized as recorded in a transverse section of the plasma, which are used in determining the actual course of the atomic concentration and the half-width of the thin-layer line. An iterative scheme is set up for determining the temperature. A mathematical experiment has been performed and the temperature distribution has been determined in the plasma of a low-voltage pulsed discharge

  4. Impact of nonlocal electron heat transport on the high temperature plasmas of LHD

    International Nuclear Information System (INIS)

    Tamura, N.; Inagaki, S.; Tokuzawa, T.

    2006-10-01

    Edge cooling experiments with a tracer-encapsulated solid pellet in the Large Helical Device (LHD) show a significant rise of core electron temperature (the maximum rise is around 1 keV) as well as in many tokamaks. This experimental result indicates the possible presence of the nonlocality of electron heat transport in plasmas where turbulence as a cause of anomalous transport is dominated. The nonlocal electron temperature rise in the LHD takes place in almost the same parametric domain (e.g. in a low density) as in the tokamaks. Meanwhile, the experimental results of LHD show some new aspects of nonlocal electron temperature rise, for example the delay of the nonlocal rise of core electron temperature relative to the pellet penetration time increases with the increase in collisionality in the core plasma and the decrease in electron temperature gradient scale length in the outer region of the plasma. (author)

  5. Impact of nonlocal electron heat transport on the high temperature plasmas of LHD

    International Nuclear Information System (INIS)

    Tamura, N.; Inagaki, S.; Tanaka, K.; Michael, C.; Tokuzawa, T.; Shimozuma, T.; Kubo, S.; Sakamoto, R.; Ida, K.; Itoh, K.; Kalinina, D.; Sudo, S.; Nagayama, Y.; Kawahata, K.; Komori, A.

    2007-01-01

    Edge cooling experiments with a tracer-encapsulated solid pellet in the large helical device (LHD) show a significant rise in core electron temperature (the maximum rise is around 1 keV) as well as in many tokamaks. This experimental result indicates the possible presence of the nonlocality of electron heat transport in plasmas where turbulence as a cause of anomalous transport dominates. The nonlocal electron temperature rise in the LHD takes place in almost the same parametric domain (e.g. in a low density) as in the tokamaks. Meanwhile, the experimental results of LHD show some new aspects of nonlocal electron temperature rise, for example the delay in the nonlocal rise of core electron temperature relative to the pellet penetration time increases with the increase both in the collisionality in the core plasma and the electron temperature gradient scale length in the outer region of the plasma

  6. Atomic and molecular hydrogen gas temperatures in a low-pressure helicon plasma

    Science.gov (United States)

    Samuell, Cameron M.; Corr, Cormac S.

    2015-08-01

    Neutral gas temperatures in hydrogen plasmas are important for experimental and modelling efforts in fusion technology, plasma processing, and surface modification applications. To provide values relevant to these application areas, neutral gas temperatures were measured in a low pressure (radiofrequency helicon discharge using spectroscopic techniques. The atomic and molecular species were not found to be in thermal equilibrium with the atomic temperature being mostly larger then the molecular temperature. In low power operation (measurements near a graphite target demonstrated localised cooling near the sample surface. The temporal evolution of the molecular gas temperature during a high power 1.1 ms plasma pulse was also investigated and found to vary considerably as a function of pressure.

  7. ICRF-enhanced plasma potentials in the SOL of Alcator C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    Ochoukov, R.; Whyte, D. G.; Brunner, D.; LaBombard, B.; Lipschultz, B.; Terry, J. L.; Wukitch, S. J. [PSFC MIT, NW17, 175 Albany Street, Cambridge, MA 02139 (United States); D' Ippolito, D. A.; Myra, J. R. [Lodestar Research Corporation, 2400 Central Avenue, Boulder, Colorado 80301 (United States)

    2014-02-12

    We performed an extensive survey of the plasma potential in the scrape-off layer (SOL) of Ion Cyclotron Range-of Frequencies (ICRF)-heated discharges on Alcator C-Mod. Our results show that plasma potentials are enhanced in the presence of ICRF power and plasma potential values of >100 V are often observed. Such potentials are high enough to induce sputtering of high-Z molybdenum (Mo) plasma facing components by deuterium ions on C-Mod. For comparison, the plasma potential in Ohmic discharges is typically less than 10 V, well below the threshold needed to induce Mo sputtering by deuterium ions. ICRF-enhanced plasma potentials are observed in the SOL regions that both magnetically map and do not map to active ICRF antennas. Regions that magnetically map to active ICRF antennas are accessible to slow waves directly launched by the antennas and these regions experience plasma potential enhancement that is partially consistent with the slow wave rectification mechanism. One of the most defining features of the slow wave rectification is a threshold appearance of significant plasma potentials (>100 V) when the dimensionless rectification parameter Λ{sub −o} is above unity and this trend is observed experimentally. We also observe ICRF-enhanced plasma potentials >100 V in regions that do not magnetically map to the active antennas and, hence, are not accessible for slow waves launched directly by the active antennas. However, unabsorbed fast waves can reach these regions. The general trend that we observe in these 'un-mapped' regions is that the plasma potential scales with the strength of the local RF wave fields with the fast wave polarization and the highest plasma potentials are observed in discharges with the highest levels of unabsorbed ICRF power. Similarly, we find that core Mo levels scale with the level of unabsorbed ICRF power suggesting a link between plasma potentials in the SOL and the strength of the impurity source.

  8. High-Temperature-High-Volume Lifting for Enhanced Geothermal Systems

    Energy Technology Data Exchange (ETDEWEB)

    Turnquist, Norman [GE Global Research, Munchen (Germany); Qi, Xuele [GE Global Research, Munchen (Germany); Raminosoa, Tsarafidy [GE Global Research, Munchen (Germany); Salas, Ken [GE Global Research, Munchen (Germany); Samudrala, Omprakash [GE Global Research, Munchen (Germany); Shah, Manoj [GE Global Research, Munchen (Germany); Van Dam, Jeremy [GE Global Research, Munchen (Germany); Yin, Weijun [GE Global Research, Munchen (Germany); Zia, Jalal [GE Global Research, Munchen (Germany)

    2013-12-20

    This report summarizes the progress made during the April 01, 2010 – December 30, 2013 period under Cooperative Agreement DE-EE0002752 for the U.S. Department of Energy entitled “High-Temperature-High-Volume Lifting for Enhanced Geothermal Systems.” The overall objective of this program is to advance the technology for well fluids lifting systems to meet the foreseeable pressure, temperature, and longevity needs of the Enhanced Geothermal Systems (EGS) industry for the coming ten years. In this program, lifting system requirements for EGS wells were established via consultation with industry experts and site visits. A number of artificial lift technologies were evaluated with regard to their applicability to EGS applications; it was determined that a system based on electric submersible pump (ESP) technology was best suited to EGS. Technical barriers were identified and a component-level technology development program was undertaken to address each barrier, with the most challenging being the development of a power-dense, small diameter motor that can operate reliably in a 300°C environment for up to three years. Some of the targeted individual component technologies include permanent magnet motor construction, high-temperature insulation, dielectrics, bearings, seals, thrust washers, and pump impellers/diffusers. Advances were also made in thermal management of electric motors. In addition to the overall system design for a full-scale EGS application, a subscale prototype was designed and fabricated. Like the full-scale design, the subscale prototype features a novel “flow-through-the-bore” permanent magnet electric motor that combines the use of high temperature materials with an internal cooling scheme that limits peak internal temperatures to <330°C. While the full-scale high-volume multi-stage pump is designed to lift up to 80 kg/s of process water, the subscale prototype is based on a production design that can pump 20 kg/s and has been modified

  9. The effect of low-temperature plasma on model organism Drosophila melanogaster

    International Nuclear Information System (INIS)

    Maronek, M.; Mentelova, L.; Kyzek, S.; Kovacik, D.

    2017-01-01

    The occurrence of various chemicals in our life creates a need to evaluate whether they pose a threat to human body. There are many methods capable of detecting potential mutagenic or genotoxic effect. The Smart test was chosen to test mutagenic effect of low-temperature plasma, which is nowadays used in medicine, material decontamination and degradation of pharmaceuticals. When a mutational event during larval development occurs, spots on the wings are being formed. The frequency and size of the spots reveals the mutagenic potency of the tested substance. To evaluate the mutagenic effect of low-temperature plasma, larvae were treated with multiple doses. Our results show that plasma did not exhibit any mutagenic effect in all of the tested doses. Next we studied if it could work as an antimutagenic agent. Experiments with plasma along with ethyl methanesulphonate (EMS), a known mutagen, suggest that plasma treatment did reduce the negative effect of EMS, thus this agents could possess antimutagenic effect. (authors)

  10. A technique for temperature mapping in fluorocarbon plasmas using planar laser-induced fluorescence of CF

    International Nuclear Information System (INIS)

    Steffens, Kristen L.; Sobolewski, Mark A.

    2004-01-01

    Planar laser-induced fluorescence measurements of CF A 2 Σ + -X 2 Π(1,0) were used to determine two-dimensional maps of rotational temperature in CF 4 plasmas. Measured rotational temperatures are expected to be in equilibrium with the gas temperature due to the long chemical lifetime of CF relative to the collision rate. Experiments were performed in the capacitively coupled Gaseous Electronics Conference rf reference cell at pressures from 26.7 Pa (200 mTorr) to 107 Pa (800 mTorr) and powers of 10 to 30 W deposited in the plasma. Temperatures, which ranged from 273±15 K to 480±15 K, were fairly axially symmetric and increased with pressure and power. All plasmas were coolest near the electrodes, which provided a substantial sink for heat in the plasma. Highest temperatures were found at a radial position near the edge of the electrodes. The strong temperature gradients observed in the plasmas can have serious effects on density measurements that probe a single rotational level, as well as on reaction rate constants and interpretation of density gradients. The effects of water-cooling the electrodes and the presence of a silicon wafer on temperature were also measured

  11. Some observations on the high temperature oxidation behaviour of plasma sprayed Ni3Al coatings

    International Nuclear Information System (INIS)

    Singh, H.; Prakash, S.; Puri, D.

    2007-01-01

    High temperature oxidation resistance of the superalloys can be greatly enhanced by plasma sprayed coatings and this is a growing industry of considerable economic importance. The purpose of these coatings is to form long-lasting oxidation protective scales. In the current investigation, Ni 3 Al powder was prepared by mechanical mixing of pure nickel and aluminium powders in a ball mill. Subsequently Ni 3 Al powder was deposited on three Ni-base superalloys: Superni 600, Superni 601 and Superni 718 and, one Fe-base superalloy, Superfer 800H by shrouded plasma spray process. Oxidation studies were conducted on the coated superalloys in air at 900 deg. C under cyclic conditions for 50 cycles. Each cycle consisted of 1 h heating followed by 20 min of cooling in air. The thermogravimetric technique was used to approximate the kinetics of oxidation. All the coated superalloys nearly followed parabolic rate law of oxidation. X-ray diffraction, SEM/EDAX and EPMA techniques were used to analyse the oxidation products. The Ni 3 Al coating was found to be successful in maintaining its adherence to the superalloy substrates in all the cases. The oxide scales formed on the oxidised coated superalloys were found to be intact and spallation-free. XRD analysis revealed the presence of phases like NiO, Al 2 O 3 and NiAl 2 O 4 in the oxide scales, which are reported as protective oxides against high temperature oxidation. The XRD results were further supported by SEM/EDAX and EPMA

  12. Compensation of decreased ion energy by increased hydrogen dilution in plasma deposition of thin film silicon solar cells at low substrate temperatures

    NARCIS (Netherlands)

    Verkerk, A.D.; de Jong, M.M.; Rath, J.K.; Brinza, M.; Schropp, R.E.I.; Goedheer, W.J.; Krzhizhanovskaya, V.V.; Gorbachev, Y.E.; Orlov, K.E.; Khilkevitch, E.M.; Smirnov, A.S.

    2009-01-01

    In order to deposit thin film silicon solar cells on plastics and papers, the deposition process needs to be adapted for low deposition temperatures. In a very high frequency plasma-enhanced chemical vapor deposition (VHF PECVD) process, both the gas phase and the surface processes are affected by

  13. An integrate-over-temperature approach for enhanced sampling.

    Science.gov (United States)

    Gao, Yi Qin

    2008-02-14

    A simple method is introduced to achieve efficient random walking in the energy space in molecular dynamics simulations which thus enhances the sampling over a large energy range. The approach is closely related to multicanonical and replica exchange simulation methods in that it allows configurations of the system to be sampled in a wide energy range by making use of Boltzmann distribution functions at multiple temperatures. A biased potential is quickly generated using this method and is then used in accelerated molecular dynamics simulations.

  14. On the enhancement of pervaporation properties of plasma-deposited hybrid silica membranes

    Energy Technology Data Exchange (ETDEWEB)

    Ngamou, P.H.T.; Creatore, M. [Department of Applied Physics, Eindhoven University of Technology, 5600 MB Eindhoven (Netherlands); Overbeek, J.P.; Kreiter, R.; Van Veen, H.M.; Vente, J.F. [ECN, Energy research Centre of the Netherlands, Petten (Netherlands); Cuperus, P.F. [SolSep BV, Apeldoorn (Netherlands)

    2013-06-24

    The separation performance of a polymeric-supported hybrid silica membrane in the dehydration process of a butanol-water mixture at 95C has been enhanced by applying a bias to the substrate during the plasma deposition.

  15. Combustion Enhancement Via Stabilized Piecewise Nonequilibrium Gliding Arc Plasma Discharge (Postprint)

    National Research Council Canada - National Science Library

    Ombrello, Timothy; Qin, Xiao; Ju, Yiguang; Gutsol, Alexander; Fridman, Alexander; Carter, Campbell

    2006-01-01

    ... enhancement of methane-air diffusion flames. The results showed that the new system provided a well-defined flame geometry for the understanding of the basic mechanism of the plasma-flame interaction...

  16. Structure of the radial electric field and toroidal/poloidal flow in high temperature toroidal plasma

    International Nuclear Information System (INIS)

    Ida, Katsumi

    2001-01-01

    The structure of the radial electric field and toroidal/poloidal flow is discussed for the high temperature plasma in toroidal systems, tokamak and Heliotron type magnetic configurations. The spontaneous toroidal and poloidal flows are observed in the plasma with improved confinement. The radial electric field is mainly determined by the poloidal flow, because the contribution of toroidal flow to the radial electric field is small. The jump of radial electric field and poloidal flow are commonly observed near the plasma edge in the so-called high confinement mode (H-mode) plasmas in tokamaks and electron root plasma in stellarators including Heliotrons. In general the toroidal flow is driven by the momentum input from neutral beam injected toroidally. There is toroidal flow not driven by neutral beam in the plasma and it will be more significant in the plasma with large electric field. The direction of these spontaneous toroidal flows depends on the symmetry of magnetic field. The spontaneous toroidal flow driven by the ion temperature gradient is in the direction to increase the negative radial electric field in tokamak. The direction of spontaneous toroidal flow in Heliotron plasmas is opposite to that in tokamak plasma because of the helicity of symmetry of the magnetic field configuration. (author)

  17. X-ray spectroscopic study of high-temperature plasmas by curved crystal spectrometer

    International Nuclear Information System (INIS)

    Morita, Shigeru.

    1983-07-01

    Extensive studies have been carried out on the structure of X-ray spectra from the highly stripped ions of first transition elements and their behavior in high temperature plasma, using a high resolution crystal spectrometer. Calculation was made on the design and the use of a curved crystal spectrometer for plasma diagnostics. A Johann type crystal spectrometer for measuring X-ray lines was constructed on the basis of the calculation. The characteristics of curved crystals of LiF, Ge and quartz used for the measurement of Kα lines from first transition elements were investigated. Vacuum sparks have been formed for producing high temperature plasma which emits X-ray lines from highly stripped ions. Two different structures of vacuum spark plasma were shown, that is, thermalized point plasma and extended plasma associated with non-thermal electrons. The X-ray lines from the extended plasma, those associated with the K shell from the point plasma and the Kα lines of Ti through Zn from the point plasma have been observed. (Kako, I.)

  18. Enhanced coagulation activation in preeclampsia: the role of APC resistance, microparticles and other plasma constituents

    NARCIS (Netherlands)

    VanWijk, Marja J.; Boer, Kees; Berckmans, René J.; Meijers, Joost C. M.; van der Post, Joris A. M.; Sturk, Augueste; VanBavel, Ed; Nieuwland, Rienk

    2002-01-01

    Coagulation activation in pregnancy is further enhanced in preeclampsia. We investigated whether this results from increased thrombin generation by the plasma itself or its cell-derived microparticles. Plasma samples were obtained from preeclamptic, normal pregnant and nonpregnant women (each n =

  19. Plasma-enhanced chemical vapor deposition of aluminum oxide using ultrashort precursor injection pulses

    NARCIS (Netherlands)

    Dingemans, G.; Sanden, van de M.C.M.; Kessels, W.M.M.

    2012-01-01

    An alternative plasma-enhanced chemical vapor deposition (PECVD) method is developed and applied for the deposition of high-quality aluminum oxide (AlOx) films. The PECVD method combines a continuous plasma with ultrashort precursor injection pulses. We demonstrate that the modulation of the

  20. Enhancing the high temperature capability of Ti-alloys

    Energy Technology Data Exchange (ETDEWEB)

    Donchev, Alexander; Schuetze, Michael [DECHEMA-Forschungsinstitut, Frankfurt/Main (Germany); Kolitsch, Andreas; Yankov, Rossen [Helmholtz-Zentrum Dresden-Rossendorf, Institute of Ion Beam Physics and Materials Research, Dresden (Germany)

    2012-08-15

    Titanium is a widely used structural material for applications below approximately 500 C but right now it cannot be used at higher temperatures. Titanium forms a fast growing rutile layer under these conditions. Furthermore enhanced oxygen uptake into the metal subsurface zone leads to embrittlement which deteriorates the mechanical properties. To overcome this problem a combined Al- plus F-treatment was developed. The combination of Al-enrichment in the surface zone so that intermetallic Ti{sub x}Al{sub y}-layers are produced which form a protective alumina layer during high temperature exposure plus stabilization of the Al{sub 2}O{sub 3}-scale by the fluorine effect led to significantly improved resistance against increased oxidation and embrittlement in high temperature exposure tests of several Ti-alloys. In this paper, the experimental procedures and achieved improvements are described. The results will be discussed for the use of Ti-alloys at elevated temperatures. (Copyright copyright 2012 WILEY-VCH Verlag GmbH and Co. KGaA, Weinheim)

  1. Emission reduction by means of low temperature plasma. Summary

    DEFF Research Database (Denmark)

    Bindslev, H.; Fateev, Alexander; Kusano, Yukihiro

    2006-01-01

    ammonia (NH3) and nitrogen atoms (N) generated in dielectric barrier discharges (DBDs). Hydrazine (N2H4) as a reducing agent and direct plasma treatment of the entire exhaust gas was investigated as well. Weperformed laboratory experiments on synthetic exhaust gases, modelling of the mechanisms......The work performed during the project is summarised. In the project we focused on removal of nitrogen oxides NOx (NO, NO2) and, in particular, on removal of nitrogen monoxide (NO) by injection of plasma-produced reactive agents. As reactive agents wetested ozone (O3), NH and NH2 radicals from...... and a demonstration of the technique on a test engine, a 30 kW combustion engine fuelled with natural gas. We achieved the best results with ozone injection into theexhaust gas. This technique is based on oxidation of NO to N2O5 that is subsequently removed from the exhaust gas by a scrubber. In the laboratory...

  2. Preparation and structure of porous dielectrics by plasma enhanced chemical vapor deposition

    International Nuclear Information System (INIS)

    Gates, S. M.; Neumayer, D. A.; Sherwood, M. H.; Grill, A.; Wang, X.; Sankarapandian, M.

    2007-01-01

    The preparation of ultralow dielectric constant porous silicon, carbon, oxygen, hydrogen alloy dielectrics, called 'pSiCOH', using a production 200 mm plasma enhanced chemical vapor deposition tool and a thermal treatment is reported here. The effect of deposition temperature on the pSiCOH film is examined using Fourier transform infrared (FTIR) spectroscopy, dielectric constant (k), and film shrinkage measurements. For all deposition temperatures, carbon in the final porous film is shown to be predominantly Si-CH 3 species, and lower k is shown to correlate with increased concentration of Si-CH 3 . NMR and FTIR spectroscopies clearly detect the loss of a removable, unstable, hydrocarbon (CH x ) phase during the thermal treatment. Also detected are increased cross-linking of the Si-O skeleton, and concentration changes for three distinct structures of carbon. In the as deposited films, deposition temperature also affects the hydrocarbon (CH x ) content and the presence of C=O and C=C functional groups

  3. Experimental investigation of ultraviolet laser induced plasma density and temperature evolution in air

    International Nuclear Information System (INIS)

    Thiyagarajan, Magesh; Scharer, John

    2008-01-01

    We present measurements and analysis of laser induced plasma neutral densities and temperatures in dry air by focusing 200 mJ, 10 MW high power, 193 nm ultraviolet ArF (argon fluoride) laser radiation to a 30 μm radius spot size. We examine these properties that result from multiphoton and collisional cascade processes for pressures ranging from 40 Torr to 5 atm. A laser shadowgraphy diagnostic technique is used to obtain the plasma electron temperature just after the shock front and this is compared with optical emission spectroscopic measurements of nitrogen rotational and vibrational temperatures. Two-color laser interferometry is employed to measure time resolved spatial electron and neutral density decay in initial local thermodynamic equilibrium (LTE) and non-LTE conditions. The radiating species and thermodynamic characteristics of the plasma are analyzed by means of optical emission spectroscopy (OES) supported by SPECAIR, a special OES program for air constituent plasmas. Core plasma rotational and vibrational temperatures are obtained from the emission spectra from the N 2 C-B(2+) transitions by matching the experimental spectrum results with the SPECAIR simulation results and the results are compared with the electron temperature just behind the shock wave. The plasma density decay measurements are compared with a simplified electron density decay model that illustrates the dominant three-and two-body recombination terms with good correlation

  4. Ion temperature profiles along a hydrogen diagnostic beam in a TORE SUPRA tokamak plasma

    International Nuclear Information System (INIS)

    Romannikov, A.; Petrov, Yu.; Platts, P.; Khess, V.; Khutter, T.; Farzhon, Zh.; Moro, F.

    2002-01-01

    By means of corpuscular diagnostics one studies temperature of ions along a diagnostic hydrogen beam. Paper presents comparison of temperature of plasma (deuterium) basic ions measures by means of the active corpuscular diagnostics with temperature of C + carbon ions along a beam. One studies behavior peculiarities of T i ion temperature profiles for TORE-SUPRA different modes, such as: formation of plane and even hollow T i profiles for ohmic modes, variation of T i profiles under operation of an ergodic diverter, difference of temperature of basic ions measured by means of the active corpuscular diagnostics from C +5 temperature. Paper offers clear explanation of these peculiarities [ru

  5. Diagnostics for Combustion and Ignition Enhancement Using the Non-Equilibrium Plasma

    National Research Council Canada - National Science Library

    Ju, Yiguang; Ombrello, Timothy; Won, Sanghee

    2008-01-01

    .... OH concentrations, O3 and O(1D) emissions, temperature distributions in plasma assisted combustion were measured by using the planar laser induced fluorescence, emission spectroscopy, and Rayleigh scattering...

  6. Temperature dependence of the cosphi conductance in Josephson tunnel junctions determined from plasma resonance experiments

    DEFF Research Database (Denmark)

    Pedersen, Niels Falsig; Sørensen, O. H.; Mygind, Jesper

    1978-01-01

    The microwave response at 9 GHz of Sn-O-Sn tunnel-junction current biased at zero dc voltage has been measured just below the critical temperature Tc of the Sn films. The temperature dependence of the cosφ conductance is determined from the resonant response at the junction plasma frequency fp...

  7. The Stark-crossing method for the simultaneous determination of the electron temperature and density in plasmas

    International Nuclear Information System (INIS)

    Torres, J; Carabano, O; Fernandez, M; Rubio, S; Alvarez, R; Rodero, A; Lao, C; Quintero, M C; Gamero, A; Sola, A

    2006-01-01

    The use of the Stark broadening of Balmer lines spontaneously emitted by atmospheric-pressure plasmas as a method to determine both the electron density and temperature in high-pressure plasmas is discussed in this paper. This method is applied to argon and helium plasmas produced in microwave discharges. Especially for Ar plasmas, valuable and reliable results are obtained

  8. Monitoring Temperature in High Enthalpy Arc-heated Plasma Flows using Tunable Diode Laser Absorption Spectroscopy

    Science.gov (United States)

    Martin, Marcel Nations; Chang, Leyen S.; Jeffries, Jay B.; Hanson, Ronald K.; Nawaz, Anuscheh; Taunk, Jaswinder S.; Driver, David M.; Raiche, George

    2013-01-01

    A tunable diode laser sensor was designed for in situ monitoring of temperature in the arc heater of the NASA Ames IHF arcjet facility (60 MW). An external cavity diode laser was used to generate light at 777.2 nm and laser absorption used to monitor the population of electronically excited oxygen atoms in an air plasma flow. Under the assumption of thermochemical equilibrium, time-resolved temperature measurements were obtained on four lines-of-sight, which enabled evaluation of the temperature uniformity in the plasma column for different arcjet operating conditions.

  9. A compact new incoherent Thomson scattering diagnostic for low-temperature plasma studies

    Science.gov (United States)

    Vincent, Benjamin; Tsikata, Sedina; Mazouffre, Stéphane; Minea, Tiberiu; Fils, Jérôme

    2018-05-01

    Incoherent Thomson scattering (ITS) has a long history of application for the determination of electron density and temperature in dense fusion plasmas, and in recent years, has been increasingly extended to studies in low-temperature plasma environments. In this work, the design and preliminary implementation of a new, sensitive and uniquely compact ITS platform known as Thomson scattering experiments for low temperature ion sources are described. Measurements have been performed on a hollow cathode plasma source, providing access to electron densities as low as 1016 m‑3 and electron temperatures of a few eV and below. This achievement has been made possible by the implementation of a narrow volume Bragg grating notch filter for the attenuation of stray light, a feature which guarantees compactness and reduced transmission losses in comparison to standard ITS platforms.

  10. Initial evolution of nonlinear magnetic islands in high temperature plasmas

    International Nuclear Information System (INIS)

    Kotschenreuther, M.

    1988-06-01

    The evolution of nonlinear magnetic islands is computed in the kinetic collisionality regime called the semicollisional regime, which is appropriate to present fusion confinement devices. Realistic effects are included, such as the presence of small external field errors, radial electric fields, and omega. When present simultaneously, these effects can greatly change the stability of small amplitude nonlinear islands. Islands with Δ' > O can sometimes be prevented from growing to macroscopic size; it is also possible to produce moderate mode-number nonlinear instabilities in the plasma edge. Furthermore, island growth can be prevented by application of external fields with suitably chosen amplitude and frequency

  11. Mass analyzer ``MASHA'' high temperature target and plasma ion source

    Science.gov (United States)

    Semchenkov, A. G.; Rassadov, D. N.; Bekhterev, V. V.; Bystrov, V. A.; Chizov, A. Yu.; Dmitriev, S. N.; Efremov, A. A.; Guljaev, A. V.; Kozulin, E. M.; Oganessian, Yu. Ts.; Starodub, G. Ya.; Voskresensky, V. M.; Bogomolov, S. L.; Paschenko, S. V.; Zelenak, A.; Tikhonov, V. I.

    2004-05-01

    A new separator and mass analyzer of super heavy atoms (MASHA) has been created at the FLNR JINR Dubna to separate and measure masses of nuclei and molecules with precision better than 10-3. First experiments with the FEBIAD plasma ion source have been done and give an efficiency of ionization of up to 20% for Kr with a low flow test leak (6 particle μA). We suppose a magnetic field optimization, using the additional electrode (einzel lens type) in the extracting system, and an improving of the vacuum conditions in order to increase the ion source efficiency.

  12. Mass analyzer 'MASHA' high temperature target and plasma ion source

    International Nuclear Information System (INIS)

    Semchenkov, A.G.; Rassadov, D.N.; Bekhterev, V.V.; Bystrov, V.A.; Chizov, A.Yu.; Dmitriev, S.N.; Efremov, A.A.; Guljaev, A.V.; Kozulin, E.M.; Oganessian, Yu.Ts.; Starodub, G.Ya.; Voskresensky, V.M.; Bogomolov, S.L.; Paschenko, S.V.; Zelenak, A.; Tikhonov, V.I.

    2004-01-01

    A new separator and mass analyzer of super heavy atoms (MASHA) has been created at the FLNR JINR Dubna to separate and measure masses of nuclei and molecules with precision better than 10 -3 . First experiments with the FEBIAD plasma ion source have been done and give an efficiency of ionization of up to 20% for Kr with a low flow test leak (6 particle μA). We suppose a magnetic field optimization, using the additional electrode (einzel lens type) in the extracting system, and an improving of the vacuum conditions in order to increase the ion source efficiency

  13. Plasmas in Multiphase Media: Bubble Enhanced Discharges in Liquids and Plasma/Liquid Phase Boundaries

    Energy Technology Data Exchange (ETDEWEB)

    Kushner, Mark Jay [University of Michigan

    2014-07-10

    In this research project, the interaction of atmospheric pressure plasmas with multi-phase media was computationally investigated. Multi-phase media includes liquids, particles, complex materials and porous surfaces. Although this investigation addressed fundamental plasma transport and chemical processes, the outcomes directly and beneficially affected applications including biotechnology, medicine and environmental remediation (e.g., water purification). During this project, we made advances in our understanding of the interaction of atmospheric pressure plasmas in the form of dielectric barrier discharges and plasma jets with organic materials and liquids. We also made advances in our ability to use computer modeling to represent these complex processes. We determined the method that atmospheric pressure plasmas flow along solid and liquid surfaces, and through endoscopic like tubes, deliver optical and high energy ion activation energy to organic and liquid surfaces, and produce reactivity in thin liquid layers, as might cover a wound. We determined the mechanisms whereby plasmas can deliver activation energy to the inside of liquids by sustaining plasmas in bubbles. These findings are important to the advancement of new technology areas such as plasma medicine

  14. Impurities, temperature, and density in a miniature electrostatic plasma and current source

    International Nuclear Information System (INIS)

    Den Hartog, D.J.; Craig, D.J.; Fiksel, G.; Sarff, J.S.

    1996-10-01

    We have spectroscopically investigated the Sterling Scientific miniature electrostatic plasma source-a plasma gun. This gun is a clean source of high density (10 19 - 10 20 m -3 ), low temperature (5 - 15 eV) plasma. A key result of our investigation is that molybdenum from the gun electrodes is largely trapped in the internal gun discharge; only a small amount escapes in the plasma flowing out of the gun. In addition, the gun plasma parameters actually improve (even lower impurity contamination and higher ion temperature) when up to 1 kA of electron current is extracted from the gun via the application of an external bias. This improvement occurs because the internal gun anode no longer acts as the current return for the internal gun discharge. The gun plasma is a virtual plasma electrode capable of sourcing an electron emission current density of 1 kA/cm 2 . The high emission current, small size (3 - 4 cm diameter), and low impurity generation make this gun attractive for a variety of fusion and plasma technology applications

  15. Integrated heat transport simulation of high ion temperature plasma of LHD

    International Nuclear Information System (INIS)

    Murakami, S.; Yamaguchi, H.; Sakai, A.

    2014-10-01

    A first dynamical simulation of high ion temperature plasma with carbon pellet injection of LHD is performed by the integrated simulation GNET-TD + TASK3D. NBI heating deposition of time evolving plasma is evaluated by the 5D drift kinetic equation solver, GNET-TD and the heat transport of multi-ion species plasma (e, H, He, C) is studied by the integrated transport simulation code, TASK3D. Achievement of high ion temperature plasma is attributed to the 1) increase of heating power per ion due to the temporal increase of effective charge, 2) reduction of effective neoclassical transport with impurities, 3) reduction of turbulence transport. The reduction of turbulence transport is most significant contribution to achieve the high ion temperature and the reduction of the turbulent transport from the L-mode plasma (normal hydrogen plasma) is evaluated to be a factor about five by using integrated heat transport simulation code. Applying the Z effective dependent turbulent reduction model we obtain a similar time behavior of ion temperature after the C pellet injection with the experimental results. (author)

  16. Studies on omnidirectional enhancement of giga-hertz radiation by sub-wavelength plasma modulation

    Science.gov (United States)

    Fanrong, KONG; Qiuyue, NIE; Shu, LIN; Zhibin, WANG; Bowen, LI; Shulei, ZHENG; Binhao, JIANG

    2018-01-01

    The technology of radio frequency (RF) radiation intensification for radio compact antennas based on modulation and enhancement effects of sub-wavelength plasma structures represents an innovative developing strategy. It exhibits important scientific significance and promising potential of broad applications in various areas of national strategic demands, such as electrical information network and microwave communication, detection and control technology. In this paper, laboratory experiments and corresponding analyses have been carried out to investigate the modulation and enhancement technology of sub-wavelength plasma structure on the RF electromagnetic radiation. An application focused sub-wavelength plasma-added intensification up to ∼7 dB higher than the free-space radiation is observed experimentally in giga-hertz (GHz) RF band. The effective radiation enhancement bandwidth covers from 0.85 to 1.17 GHz, while the enhanced electromagnetic signals transmitted by sub-wavelength plasma structures maintain good communication quality. Particularly, differing from the traditional RF electromagnetic radiation enhancement method characterized by focusing the radiation field of antenna in a specific direction, the sub-wavelength plasma-added intensification of the antenna radiation presents an omnidirectional enhancement, which is reported experimentally for the first time. Corresponding performance characteristics and enhancement mechanism analyses are also conducted in this paper. The results have demonstrated the feasibility and promising potential of sub-wavelength plasma modulation in application focused RF communication, and provided the scientific basis for further research and development of sub-wavelength plasma enhanced compact antennas with wide-range requests and good quality for communication.

  17. 8th Symposium on elementary processes and chemical reactions in low temperature plasma. Pt. 1 and 2

    International Nuclear Information System (INIS)

    Morvova, M.

    1990-11-01

    The document contains invited papers on low temperature plasma physics and its application. Among them, 9 papers deal with the experimental and theoretical investigation and modelling of elementary plasma processes and particle kinematics in electric discharges of various type and purpose. Each of the following 3 papers presents a survey of some advanced plasma technology, as are laser plasma chemistry, plasma production of diamond-like carbon films and of special fine powders. The ionized Van der Waals clusters, shock waves in interplanetary plasma, and plasma acceleration in electromagnetic plasma launchers are the topics of the remaining three papers. (J.U.)

  18. Dosimetry of x-rays from high-temperature plasmas

    International Nuclear Information System (INIS)

    Yamamoto, Takayoshi; Abe, Nobuyuki; Kawanishi, Masaharu

    1980-01-01

    Study on the dosimetry of ionizing radiations, especially of X-rays, emitted from high-temperature plasms has been made. As to the unpolarized Bremsstrahlung, a brief method to estimate electron temperatures with TLD is described and evaluation of average energy and current of the run-away electrons in the turbulent heating Tokamak is made by observing the half-value layer of the emitted X-rays and the total exposure per one shot of the Tokamak discharge. As to the polarized one, it is shown that the anisotropic electron temperature is related to the degree of polarization of the X-rays. Furthermore, reference is made to the possibility of developing such X-ray generators as can emit nearly monochromatic X-rays (characteristic X-rays) or polarized ones arbitrarily. (author)

  19. Tripolar vortex formation in dense quantum plasma with ion-temperature-gradients

    Science.gov (United States)

    Qamar, Anisa; Ata-ur-Rahman, Mirza, Arshad M.

    2012-05-01

    We have derived system of nonlinear equations governing the dynamics of low-frequency electrostatic toroidal ion-temperature-gradient mode for dense quantum magnetoplasma. For some specific profiles of the equilibrium density, temperature, and ion velocity gradients, the nonlinear equations admit a stationary solution in the form of a tripolar vortex. These results are relevant to understand nonlinear structure formation in dense quantum plasmas in the presence of equilibrium ion-temperature and density gradients.

  20. Tripolar vortex formation in dense quantum plasma with ion-temperature-gradients

    Energy Technology Data Exchange (ETDEWEB)

    Qamar, Anisa; Ata-ur-Rahman [Institute of Physics and Electronics, University of Peshawar, Khyber Pakhtoon Khwa 25000 (Pakistan); National Center for Physics Shahdrah Valley Road, Islamabad 44000 (Pakistan); Mirza, Arshad M. [Theoretical Plasma Physics Group, Physics Department, Quaid-i-Azam University, Islamabad 45320 (Pakistan)

    2012-05-15

    We have derived system of nonlinear equations governing the dynamics of low-frequency electrostatic toroidal ion-temperature-gradient mode for dense quantum magnetoplasma. For some specific profiles of the equilibrium density, temperature, and ion velocity gradients, the nonlinear equations admit a stationary solution in the form of a tripolar vortex. These results are relevant to understand nonlinear structure formation in dense quantum plasmas in the presence of equilibrium ion-temperature and density gradients.

  1. Tripolar vortex formation in dense quantum plasma with ion-temperature-gradients

    International Nuclear Information System (INIS)

    Qamar, Anisa; Ata-ur-Rahman; Mirza, Arshad M.

    2012-01-01

    We have derived system of nonlinear equations governing the dynamics of low-frequency electrostatic toroidal ion-temperature-gradient mode for dense quantum magnetoplasma. For some specific profiles of the equilibrium density, temperature, and ion velocity gradients, the nonlinear equations admit a stationary solution in the form of a tripolar vortex. These results are relevant to understand nonlinear structure formation in dense quantum plasmas in the presence of equilibrium ion-temperature and density gradients.

  2. Plasma-catalytic reforming of ethanol: influence of air activation rate and reforming temperature

    International Nuclear Information System (INIS)

    Nedybaliuk, O.A.; Chernyak, V.Ya.; Fedirchuk, I.I.; Demchina, V.P.; Bortyshevsky, V.A.; Korzh, R.V.

    2016-01-01

    This paper presents the study of the influence that air activation rate and reforming temperature have on the gaseous products composition and conversion efficiency during the plasma-catalytic reforming of ethanol. The analysis of product composition showed that the conversion efficiency of ethanol has a maximum in the studied range of reforming temperatures. Researched system provided high reforming efficiency and high hydrogen energy yield at the lower temperatures than traditional conversion technologies

  3. Ion emission from laser-produced plasmas with two electron temperatures

    International Nuclear Information System (INIS)

    Wickens, L.M.; Allen, J.E.; Rumsby, P.T.

    1978-01-01

    An analytic theory for the expansion of a laser-produced plasma with two electron temperatures is presented. It is shown that from the ion-emission velocity spectrum such relevant parameters as the hot- to -cold-electron density ratio, the absolute hot- and cold-electron temperatures, and a sensitive measure of hot- and cold-electron temperature ratio can be deduced. A comparison with experimental results is presented

  4. Plasma processing of fibre materials for enhanced impact protection

    NARCIS (Netherlands)

    Creyghton, Y.L.M.; Simor, M.

    2009-01-01

    The performance of lightweight impact protective clothing depends on the constituting materials, their assembly in a system and interaction under various dynamic impact conditions. In this paper an overview of options for improved impact protective clothing systems based on a new plasma technology

  5. Diamond films deposited by oxygen-enhanced linear plasma chemistry

    Czech Academy of Sciences Publication Activity Database

    Kromka, Alexander; Babchenko, Oleg; Ižák, Tibor; Varga, Marián; Davydova, Marina; Krátká, Marie; Rezek, Bohuslav

    2013-01-01

    Roč. 5, č. 6 (2013), s. 509-514 ISSN 2164-6627 R&D Projects: GA ČR(CZ) GBP108/12/G108; GA ČR GAP108/12/0996 Institutional support: RVO:68378271 Keywords : diamond films * process gas chemistry * pulsed microwave plasma * surface conductivity of diamond Subject RIV: BM - Solid Matter Physics ; Magnetism

  6. Role of atom--atom inelastic collisions in two-temperature nonequilibrium plasmas

    International Nuclear Information System (INIS)

    Kunc, J.A.

    1987-01-01

    The contribution of inelastic atom--atom collisions to the production of electrons and excited atoms in two-temperature (with electron temperature T/sub e/, atomic temperature T/sub a/, and atomic density N/sub a/), steady-state, nonequilibrium atomic hydrogen plasma is investigated. The results are valid for plasmas having large amounts of atomic hydrogen as one of the plasma components, so that e--H and H--H inelastic collisions and interaction of these atoms with radiation dominate the production of electrons and excited hydrogen atoms. Densities of electrons and excited atoms are calculated in low-temperature plasma, with T/sub e/ and T/sub a/≤8000 K and 10 16 cm -3 ≤N/sub a/≤10 18 cm -3 , and with different degrees of the reabsorption of radiation. The results indicate that inelastic atom--atom collisions are important for production of electrons and excited atoms in partially ionized plasmas with medium and high atomic density and temperatures below 8000 K

  7. Enhanced room temperature ferromagnetism in antiferromagnetic NiO nanoparticles

    Energy Technology Data Exchange (ETDEWEB)

    Ravikumar, Patta; Kisan, Bhagaban; Perumal, A., E-mail: perumal@iitg.ernet.in [Department of Physics, Indian institute of Technology Guwahati, Guwahati 781 039 (India)

    2015-08-15

    We report systematic investigations of structural, vibrational, resonance and magnetic properties of nanoscale NiO powders prepared by ball milling process under different milling speeds for 30 hours of milling. Structural properties revealed that both pure NiO and as-milled NiO powders exhibit face centered cubic structure, but average crystallite size decreases to around 11 nm along with significant increase in strain with increasing milling speed. Vibrational properties show the enhancement in the intensity of one-phonon longitudinal optical (LO) band and disappearance of two-magnon band due to size reduction. In addition, two-phonon LO band exhibits red shift due to size-induced phonon confinement effect and surface relaxation. Pure NiO powder exhibit antiferromagnetic nature, which transforms into induced ferromagnetic after size reduction. The average magnetization at room temperature increases with decreasing the crystallite size and a maximum moment of 0.016 μ{sub B}/f.u. at 12 kOe applied field and coercivity of 170 Oe were obtained for 30 hours milled NiO powders at 600 rotation per minute milling speed. The change in the magnetic properties is also supported by the vibrational properties. Thermomagnetization measurements at high temperature reveal a well-defined magnetic phase transition at high temperature (T{sub C}) around 780 K due to induced ferromagnetic phase. Electron paramagnetic resonance (EPR) studies reveal a good agreement between the EPR results and magnetic properties. The observed results are described on the basis of crystallite size variation, defect density, large strain, oxidation/reduction of Ni and interaction between uncompensated surfaces and particle core with lattice expansion. The obtained results suggest that nanoscale NiO powders with high T{sub C} and moderate magnetic moment at room temperature with cubic structure would be useful to expedite for spintronic devices.

  8. Enhanced room temperature ferromagnetism in antiferromagnetic NiO nanoparticles

    Directory of Open Access Journals (Sweden)

    Patta Ravikumar

    2015-08-01

    Full Text Available We report systematic investigations of structural, vibrational, resonance and magnetic properties of nanoscale NiO powders prepared by ball milling process under different milling speeds for 30 hours of milling. Structural properties revealed that both pure NiO and as-milled NiO powders exhibit face centered cubic structure, but average crystallite size decreases to around 11 nm along with significant increase in strain with increasing milling speed. Vibrational properties show the enhancement in the intensity of one-phonon longitudinal optical (LO band and disappearance of two-magnon band due to size reduction. In addition, two-phonon LO band exhibits red shift due to size-induced phonon confinement effect and surface relaxation. Pure NiO powder exhibit antiferromagnetic nature, which transforms into induced ferromagnetic after size reduction. The average magnetization at room temperature increases with decreasing the crystallite size and a maximum moment of 0.016 μB/f.u. at 12 kOe applied field and coercivity of 170 Oe were obtained for 30 hours milled NiO powders at 600 rotation per minute milling speed. The change in the magnetic properties is also supported by the vibrational properties. Thermomagnetization measurements at high temperature reveal a well-defined magnetic phase transition at high temperature (TC around 780 K due to induced ferromagnetic phase. Electron paramagnetic resonance (EPR studies reveal a good agreement between the EPR results and magnetic properties. The observed results are described on the basis of crystallite size variation, defect density, large strain, oxidation/reduction of Ni and interaction between uncompensated surfaces and particle core with lattice expansion. The obtained results suggest that nanoscale NiO powders with high TC and moderate magnetic moment at room temperature with cubic structure would be useful to expedite for spintronic devices.

  9. Experimental observations of the plasma properties of a high-density, low-temperature accelerated arc

    International Nuclear Information System (INIS)

    Thomas, K.A.

    1991-01-01

    The existence of an absorbing layer, or buffer zone, of weakly ionized gas between the rear of the projectile and the front of the plasma arc armature in a plasma accelerator was demonstrated. A technique was developed to accurately determine the position of the projectile as it accelerates along the bore of the device. The projectile position is compared to that of the plasma arc as measured by magnetic field probes. These measurements provide the basis for a description of the in-bore motion of the projectile with respect to the plasma arc. Observations of this motion in plasma accelerators of 0.6 and 2.4 m lengths show the buffer zone can be as large as 50 times the bore diameter. In-bore measurements of the broadband light emission and pressure of both the buffer region and the plasma arc armature are correlated with the known projectile position to determine the characteristics of both the buffer zone and the plasma arc. Time-integrated spectral measurements of the emission taken through both the side insulators and the electrodes indicate the existence of a nonuniform plasma temperature and of turbulence in the plasma. The presence of molecular species is attributed with the ablation of the side insulator material

  10. Non-equilibrium microwave plasma for efficient high temperature chemistry

    NARCIS (Netherlands)

    van den Bekerom, D.C.M.; den Harder, N.; Minea, T.; Palomares Linares, J.M.; Bongers, W.; van de Sanden, M.C.M.; van Rooij, G.J.

    2017-01-01

    This article describes a flowing microwave reactor that is used to drive efficient non-equilibrium chemistry for the application of conversion/activation of stable molecules such as CO2, N2 and CH4. The goal of the procedure described here is to measure the in situ gas temperature and gas

  11. 2-D Imaging of Electron Temperature in Tokamak Plasmas

    International Nuclear Information System (INIS)

    Munsat, T.; Mazzucato, E.; Park, H.; Domier, C.W.; Johnson, M.; Luhmann, N.C. Jr.; Wang, J.; Xia, Z.; Classen, I.G.J.; Donne, A.J.H.; Pol, M.J. van de

    2004-01-01

    By taking advantage of recent developments in millimeter wave imaging technology, an Electron Cyclotron Emission Imaging (ECEI) instrument, capable of simultaneously measuring 128 channels of localized electron temperature over a 2-D map in the poloidal plane, has been developed for the TEXTOR tokamak. Data from the new instrument, detailing the MHD activity associated with a sawtooth crash, is presented

  12. Saha and temperature relaxation approximations for the study of ionization instability in partially ionized plasma

    International Nuclear Information System (INIS)

    Numano, M.

    1976-01-01

    The growth rates for the ionization instability obtained using the Saha and temperature relaxation approximations are compared with those obtained from an exact treatment, and the requirements for validity of these two approximations are obtained analytically. For the range of plasma parameters pertinent to MHD power generation it is found that the Saha approximation is valid for relatively high electron temperature, which it becomes inapplicable as the electron temperature is decreased. On the other hand, the temperature relaxation approximation is accurate over a wide range of electron temperature. It is found also that the marginal condition for the ionization instability is correctly obtained from both approximations. (author)

  13. Pulse pileup effects of plasma electron temperature measurements by soft x-ray energy analysis

    International Nuclear Information System (INIS)

    Dyer, G.R.; Neilson, G.H.; Kelley, G.G.

    1978-10-01

    The electron temperature of hot plasmas is conveniently derived from bremsstrahlung spectra obtained by pulse-height analysis using a lithium-compensated silicon detector. Time-resolved temperature measurements require high counting rates, with ultimate rate limited by pulse pileup. To evaluate this limit, spectral distortion due to pileup and consequent effects on temperature determination are investigated. Expressions for distorted spectra are derived as functions of Maxwellian temperature and pileup fraction for both square and triangular pulse shapes. A comparison of temperatures obtained from distorted spectra with actual values indicates that measurements with less than 10% error can be made in the absence of line radiation, even from spectra containing 40% pileup

  14. Plasma rotation and ion temperature measurements by collective Thomson scattering at ASDEX Upgrade

    DEFF Research Database (Denmark)

    Stejner Pedersen, Morten; Nielsen, Stefan Kragh; Jacobsen, Asger Schou

    2015-01-01

    We present the first deuterium ion temperature and rotation measurements by collective Thomson scattering at ASDEX Upgrade. The results are in general agreement with boron-based charge exchange recombination spectroscopy measurements and consistent with neoclassical simulations for the plasma sce...... scenario studied here. This demonstration opens the prospect for direct non-perturbative measurements of the properties of the main ion species in the plasma core with applications in plasma transport and confinement studies.......We present the first deuterium ion temperature and rotation measurements by collective Thomson scattering at ASDEX Upgrade. The results are in general agreement with boron-based charge exchange recombination spectroscopy measurements and consistent with neoclassical simulations for the plasma...

  15. Experimental observation of electron-temperature-gradient turbulence in a laboratory plasma.

    Science.gov (United States)

    Mattoo, S K; Singh, S K; Awasthi, L M; Singh, R; Kaw, P K

    2012-06-22

    We report the observation of electron-temperature-gradient (ETG) driven turbulence in the laboratory plasma of a large volume plasma device. The removal of unutilized primary ionizing and nonthermal electrons from uniform density plasma and the imposition and control of the gradient in the electron temperature (T[Symbol: see text] T(e)) are all achieved by placing a large (2 m diameter) magnetic electron energy filter in the middle of the device. In the dressed plasma, the observed ETG turbulence in the lower hybrid range of frequencies ν = (1-80 kHz) is characterized by a broadband with a power law. The mean wave number k perpendicular ρ(e) = (0.1-0.2) satisfies the condition k perpendicular ρ(e) ≤ 1, where ρ(e) is the electron Larmor radius.

  16. Growth and characterization of nanodiamond layers prepared using the plasma-enhanced linear antennas microwave CVD system

    Energy Technology Data Exchange (ETDEWEB)

    Fendrych, Frantisek; Taylor, Andrew; Peksa, Ladislav; Kratochvilova, Irena; Kluiber, Zdenek; Fekete, Ladislav [Institute of Physics, Academy of Sciences of the Czech Republic, v.v.i, Na Slovance 2, CZ-18221 Prague 8 (Czech Republic); Vlcek, Jan [Department of Physics and Measurement, Institute of Chemical Technology Prague, Technicka 5, CZ-16628 Prague 6 (Czech Republic); Rezacova, Vladimira; Petrak, Vaclav [Faculty of Biomedical Engineering, Czech Technical University, Sitna 3105, CZ-27201 Kladno 2 (Czech Republic); Liehr, Michael [Leybold Optics Dresden GmbH, Zur Wetterwarte 50, D-01109 Dresden (Germany); Nesladek, Milos, E-mail: fendrych@fzu.c [IMOMEC division, IMEC, Institute for Materials Research, University Hasselt, Wetenschapspark 1, B-3590 Diepenbeek (Belgium)

    2010-09-22

    Industrial applications of plasma-enhanced chemical vapour deposition (CVD) diamond grown on large area substrates, 3D shapes, at low substrate temperatures and on standard engineering substrate materials require novel plasma concepts. Based on the pioneering work of the group at AIST in Japan, the high-density coaxial delivery type of plasmas has been explored (Tsugawa et al 2006 New Diamond Front. Carbon Technol. 16 337-46). However, an important challenge is to obtain commercially interesting growth rates at very low substrate temperatures. In this work we introduce the concept of novel linear antenna sources, designed at Leybold Optics Dresden, using high-frequency pulsed MW discharge with a high plasma density. This type of pulse discharges leads to the preparation of nanocrystalline diamond (NCD) thin films, compared with ultra-NCD thin films prepared in (Tsugawa et al 2006 New Diamond Front. Carbon Technol. 16 337-46). We present optical emission spectroscopy data for the CH{sub 4}-CO{sub 2}-H{sub 2} gas chemistry and we discuss the basic properties of the NCD films grown.

  17. Atomic and plasma-material interaction data for fusion. V. 7, part B. Particle induced erosion of Be, C and W in fusion plasmas. Part B: Physical sputtering and radiation-enhanced sublimation

    International Nuclear Information System (INIS)

    Eckstein, W.; Stephens, J.A.; Clark, R.E.H.; Davis, J.W.; Haasz, A.A.; Vietzke, E.; Hirooka, Y.

    2001-01-01

    The present volume of Atomic and Plasma-Material Interaction Data for Fusion is devoted to a critical review of the physical sputtering and radiation enhanced sublimation (RES) behaviour of fusion plasma-facing materials, in particular carbon, beryllium and tungsten. The present volume is intended to provide fusion reactor designers a detailed survey and parameterization of existing, critically assessed data for the chemical erosion of plasma-facing materials by particle impact. The survey and data compilation is presented for a variety of materials containing the elements C, Be and W (including dopants in carbon materials) and impacting plasma species. The dependencies of physical sputtering and RES yields on the material temperature, incident projectile energy, and incident flux are considered. The main data compilation is presented as separate data sheets indicating the material, impacting plasma species, experimental conditions, and parameterizations in terms of analytic functions

  18. Absorption of high-frequency electromagnetic energy in a high-temperature plasma

    Energy Technology Data Exchange (ETDEWEB)

    Sagdeyev, R S; Shafranov, V D

    1958-07-01

    In this paper an analysis of the cyclotron and Cherenkov mechanisms is given. These are two fundamental mechanisms for noncollisional absorption of electromagnetic radiation by plasma in a magnetic field. The expressions for the dielectric permeability tensor, for plasma with a nonisotropic temperature distribution in a magnetic field, are obtained by integrating the kinetic equation with Lagrangian particle co-ordinates in a form suitable to allow a comprehensive physical interpretation of the absorption mechanisms. The oscillations of a plasma column stabilized by a longitudinal field have been analyzed. For uniform plasma, the frequency spectrum has been obtained together with the direction of electromagnetic wave propagation when both the cyclotron and Cherenkov absorption mechanisms take place. The influence of nonlinear effects on the electromagnetic wave absorption and the part which cyclotron and Cherenkov absorption play in plasma heating have also been investigated.

  19. A review of the methods to measure the ion temperature in a tokamak plasma

    International Nuclear Information System (INIS)

    Zurro Hernandez, B.; Perez-Navarro Gomez, A.

    1976-01-01

    The most important methods to measure the ion temperatu--re in a Tokamak plasma are reviewed, e.g. energy analysis of the fast neutrals which leave out the plasma, Doppler broadening of the emision spectral lines and fusion neutron analysis. It is discussed their bounds so as the advantages and drawbacks of each one. Other methods of some interest in the future are outlined. (author) [es

  20. Electron density and temperature profile diagnostics for C-2 field reversed configuration plasmas

    Energy Technology Data Exchange (ETDEWEB)

    Deng, B. H.; Kinley, J. S.; Schroeder, J. [Tri Alpha Energy, Inc., Rancho Santa Margarita, California 92688 (United States)

    2012-10-15

    The 9-point Thomson scattering diagnostic system for the C-2 field reversed configuration plasmas is improved and the measured electron temperature profiles are consistent with theoretical expectations. Rayleigh scattering revealed a finite line width of the ruby laser emission, which complicates density calibration. Taking advantage of the plasma wobble motion, density profile reconstruction accuracy from the 6-chord two-color CO{sub 2}/HeNe interferometer data is improved.

  1. CH spectroscopy for carbon chemical erosion analysis in high density low temperature hydrogen plasma

    NARCIS (Netherlands)

    Westerhout, J.; Cardozo, N. J. L.; Rapp, J.; van Rooij, G. J.

    2009-01-01

    The CH A-X molecular band is measured upon seeding the hydrogen plasma in the linear plasma generator Pilot-PSI [electron temperature T-e=0.1-2.5 eV and electron density n(e)=(0.5-5) X 10(20) m(-3)] with methane. Calculated inverse photon efficiencies for these conditions range from 3 up to

  2. Investigation of RF-enhanced plasma potentials on Alcator C-Mod

    Energy Technology Data Exchange (ETDEWEB)

    Ochoukov, R., E-mail: ochoukov@psfc.mit.edu [PSFC MIT, NW17, 175 Albany Street, Cambridge, MA 02139 (United States); Whyte, D.G.; Brunner, D. [PSFC MIT, NW17, 175 Albany Street, Cambridge, MA 02139 (United States); Cziegler, I. [Center for Energy Research, UCSD, 9500 Gilman Drive, La Jolla, CA 92093 (United States); LaBombard, B.; Lipschultz, B. [PSFC MIT, NW17, 175 Albany Street, Cambridge, MA 02139 (United States); Myra, J. [Lodestar Research Corporation, 2400 Central Avenue P-5, Boulder, CO 80301 (United States); Terry, J.; Wukitch, S. [PSFC MIT, NW17, 175 Albany Street, Cambridge, MA 02139 (United States)

    2013-07-15

    Radio frequency (RF) sheath rectification is a leading mechanism suspected of causing anomalously high erosion of plasma facing materials in RF-heated plasmas on Alcator C-Mod. An extensive experimental survey of the plasma potential (Φ{sub P}) in RF-heated discharges on C-Mod reveals that significant Φ{sub P} enhancement (>100 V) is found on outboard limiter surfaces, both mapped and not mapped to active RF antennas. Surfaces that magnetically map to active RF antennas show Φ{sub P} enhancement that is, in part, consistent with the recently proposed slow wave rectification mechanism. Surfaces that do not map to active RF antennas also experience significant Φ{sub P} enhancement, which strongly correlates with the local fast wave intensity. In this case, fast wave rectification is a leading candidate mechanism responsible for the observed enhancement.

  3. Investigation of RF-enhanced plasma potentials on Alcator C-Mod

    International Nuclear Information System (INIS)

    Ochoukov, R.; Whyte, D.G.; Brunner, D.; Cziegler, I.; LaBombard, B.; Lipschultz, B.; Myra, J.; Terry, J.; Wukitch, S.

    2013-01-01

    Radio frequency (RF) sheath rectification is a leading mechanism suspected of causing anomalously high erosion of plasma facing materials in RF-heated plasmas on Alcator C-Mod. An extensive experimental survey of the plasma potential (Φ P ) in RF-heated discharges on C-Mod reveals that significant Φ P enhancement (>100 V) is found on outboard limiter surfaces, both mapped and not mapped to active RF antennas. Surfaces that magnetically map to active RF antennas show Φ P enhancement that is, in part, consistent with the recently proposed slow wave rectification mechanism. Surfaces that do not map to active RF antennas also experience significant Φ P enhancement, which strongly correlates with the local fast wave intensity. In this case, fast wave rectification is a leading candidate mechanism responsible for the observed enhancement

  4. Enhancement of the incoherent scattering plasma lines due to precipitating protons and secondary electrons

    International Nuclear Information System (INIS)

    Bjoernaa, N.; Havnes, O.; Jensen, J.O.; Trulsen, J.

    1982-01-01

    Precipitating protons in the energy range 1-100 keV are regularly present in the auroral ionosphere. These protons will produce enhancements in the intensity of the upshifted plasma line of the incoherently scattered spectrum. Similarly, secondary electrons produced by the precipitating protons give rise to enhanced plasma line intensities. For a quantitative discussion of these effects an experimentally measured proton flux is adapted and the corresponding secondary electron flux calculated. These particle fluxes are then applied in connection with the EISCAT radar facility. Both fluxes give rise to enhancements of the order of 20. It is possible to separate between proton and electron contributions to the enhanced plasma lines for scattering heights above the source region of secondary electrons. (Auth.)

  5. Hydrogen plasma enhanced alignment on CNT-STM tips grown by liquid catalyst-assisted microwave plasma-enhanced chemical vapor deposition

    International Nuclear Information System (INIS)

    Tung, Fa-Kuei; Yoshimura, Masamichi; Ueda, Kazuyuki; Ohira, Yutaka; Tanji, Takayoshi

    2008-01-01

    Carbon nanotubes are grown directly on a scanning tunneling microscopy tip by liquid catalyst-assisted microwave-enhanced chemical vapor deposition, and effects of hydrogen plasma treatment on the tip have been investigated in detail by field-emission scanning electron microscopy (FESEM), transmission electron microscopy (TEM) and Raman spectroscopy. The unaligned CNTs on the as-grown tip apex have been realigned and reshaped by subsequent hydrogen plasma treatment. The diameter of CNTs is enlarged mainly due to amorphous layers being re-sputtered over their outer shells

  6. Enhancement of gas sensor response of nanocrystalline zinc oxide for ammonia by plasma treatment

    International Nuclear Information System (INIS)

    Hou, Yue; Jayatissa, Ahalapitiya H.

    2014-01-01

    The effect of oxygen plasma treatment on nanocrystalline ZnO thin film based gas sensor was investigated. ZnO thin films were synthesized on alkali-free glass substrates by a sol–gel process. ZnO thin films were treated with oxygen plasma to change the number of vacancies/defects in ZnO. The effect of oxygen plasma on the structural, electrical, optical and gas sensing properties was investigated as a function of plasma treatment time. The results suggest that the microstructure and the surface morphology can be tuned by oxygen plasma treatment. The optical transmission in the visible range varies after the oxygen plasma treatment. Moreover, it is found that the oxygen plasma has significant impact on the electrical properties of ZnO thin films indicating a variation of resistivity. The oxygen plasma treated ZnO thin film exhibits an enhanced sensing response towards NH 3 in comparison with that of the as-deposited ZnO sensor. When compared with the as-deposited ZnO film, the sensing response was improved by 50% for the optimum oxygen plasma treatment time of 8 min. The selectivity of 8 min plasma treated ZnO sensor was also examined for an important industrial gas mixture of H 2 , CH 4 and NH 3 .

  7. Integrated discharge scenario for high-temperature helical plasma on LHD

    International Nuclear Information System (INIS)

    Nagaoka, K.; Takahashi, H.; Murakami, S.

    2014-10-01

    Discharge scenario of high temperature plasma with helical configuration has been significantly progressed. The increase of central ion temperature due to reduction of wall recycling was clearly observed. The neutral particle profile was measured with a high-dynamic range of Balmer-α spectroscopy, and the reduction of neutral density was identified after helium conditioning main discharges. The peaking of ion heating profile and the reduction of charge exchange loss of energetic ions play an important role for improvement of ion heat transport in the core. The ion ITB and electron ITB have been successfully integrated due to superposition of centrally focused electron cyclotron heating to the ion ITB plasma, and the high temperature regime of T i ∼T e has been significantly extended. The normalized temperature gradient of ion and electron (R/L T ) were observed to exceed 10, indicating the significant improvement of both ion and electron heat transports at the barrier position. The positive radial electric field was observed by heavy ion beam probe, while the negative radial electric field was observed in ion ITB plasmas. The ion temperature gradient was observed to decrease with the increase of temperature ratio (T e /T i ). This experiment demonstrated that the profile control is a key to combine ion ITB and electron ITB and have a potential to improve the performance of helical plasmas. (author)

  8. Nonlinear phenomena in the interaction of microwaves with the low-temperature argon plasma flux

    International Nuclear Information System (INIS)

    Armand, N.A.; Lisitskaya, A.A.; Rogashkov, S.A.; Rogashkova, A.I.; Chmil', A.I.; Shustin, E.G.

    1982-01-01

    Theoretical and experimental investigations of nonlinear effects arising during the passing of SHF waves across an argon plasma jet flowing from an arc plasmatron have been carried on. It is shown that under conditions of the radiowave propagation through low temperature plasma moving across the direction of the wave propagation modes of both the wave self-focusing and its nonlinear asymmetrical refaction can be accomplished. The effect of the formation and propagation of the additional ionization region in a microwave flow initiated with plasma independently produced in the region of the maximum amplitude of the SHF field has been experimentally discovered [ru

  9. On the physics of the pressure and temperature gradients in the edge of tokamak plasmas

    Science.gov (United States)

    Stacey, Weston M.

    2018-04-01

    An extended plasma fluid theory including atomic physics, radiation, electromagnetic and themodynamic forces, external sources of particles, momentum and energy, and kinetic ion orbit loss is employed to derive theoretical expressions that display the role of the various factors involved in the determination of the pressure and temperature gradients in the edge of tokamak plasmas. Calculations for current experiments are presented to illustrate the magnitudes of various effects including strong radiative and atomic physics edge cooling effects and strong reduction in ion particle and energy fluxes due to ion orbit loss in the plasma edge. An important new insight is the strong relation between rotation and the edge pressure gradient.

  10. On the potential of CARS spectroscopy in low-temperature plasma diagnostics

    International Nuclear Information System (INIS)

    Ambrazyavichyus, A.B.; Gladkov, S.M.; Grigajtis, Yu.P.; Koroteev, N.I.

    1989-01-01

    The principles of coherent anti-Stokes Raman spectroscopy (CARS) and its application to the diagnostics of technological plasmas are briefly discussed. THe CARS spectrometer is described, developed in IPTPE, Caunas for investigations of a nitrogen plasma stream generated by an industrial plasmatron, and several CARS spectra of nitrogen molecules are presented. As the CARS signal from vibrational-rotational energy levels decreases substantially at plasma temperatures above 2000 K, an alternative scheme using electronlevels of atoms or ions has to be used. To test the method, CARS signals from the lines of the first nitrogen ion were studied in a low-voltage spark discharge. (J.U.)

  11. Electron temperature measurements by the plasma line technique at the French incoherent scatter radar facilities

    International Nuclear Information System (INIS)

    Kofman, W.; Lejeune, G.; Hagfors, T.; Bauer, P.

    1981-01-01

    The results of experiments aimed at the determination of the electron temperature by a plasma line technique are presented. Using the multistatic capabilities of the French incoherent scatter radar, the plasma line frequencies were simultaneously measured at two receiving stations (Mende and Nancay) at the altitude corresponding to the maximum of the F layer. Different plasma line frequencies are measued because of different effective k vectors that appear in the thermal term of the plasma dispersion relation. We derive and apply two data analysis procedures that enable us to determine this frequency difference. Comparison of this measured frequency difference to that calculated using the ion component electron temperature demonstrates that the plasma lines could indeed be used to determine the electron temperature. A strong dependence of the power in the plasma line as a function of the angle between k vector and magnetic field is observed in agreement with the theory. The future developments of this technique with the EISCAT radar facilities are discussed

  12. Temperature Distribution of the Ionospheric Plasma at F Layer

    Directory of Open Access Journals (Sweden)

    Hwang-Jae Rhee

    1997-12-01

    Full Text Available Langmuir probe was housed in the sounding rocket to test the probe's performance and to find the environmental parameters at the F layer of the ionosphere. The gold plated cylindrical probe had a length of 14§¯ and a diameter of 0.096 §¯. The applied voltage to the probe consisted of 0.9 sec fixed positive bias followed by 0.1 sec of down/up sweep. This ensured that the probe swept through the probe's current-voltage characteristic at least once during 1 second quiescent periods enabling the electron temperature to be measured during the undisturbed times of the flight. The experimental results showed good agreement of the temperature distribution with IRI model at the lower F layer. In the upper layer, the experimental temperatures were 100-200K lower than the IRI model's because of the different geomagnetic conditions: averaged conditions were used in IRI model and specific conditions were reflected in the experiment.

  13. Inactivation of possible micromycete food contaminants using the low-temperature plasma and hydrogen peroxide

    International Nuclear Information System (INIS)

    Čeřovský, M.; Khun, J.; Rusová, K.; Scholtz, V.; Soušková, H.

    2013-01-01

    The inhibition effect of hydrogen peroxide aerosol, low-temperature plasma and their combinations has been studied on several micromycetes spores. The low-temperature plasma was generated in corona discharges in the open air apparatus with hydrogen peroxide aerosol. Micromycete spores were inoculated on the surface of agar plates, exposed solely to the hydrogen peroxide aerosol, corona discharge or their combination. After incubation the diameter of inhibition zone was measured. The solely positive corona discharge exhibits no inactivation effect, the solely negative corona discharge and solely hydrogen peroxide aerosol exhibit the inactivation effect, however their combinations exhibit to be much more effective. Low-temperature plasma and hydrogen peroxide aerosol present a possible alternative method of microbial decontamination of food, food packages or other thermolabile materials

  14. Inactivation of possible micromycete food contaminants using the low-temperature plasma and hydrogen peroxide

    Energy Technology Data Exchange (ETDEWEB)

    Čeřovský, M., E-mail: scholtz@aldebaran.cz [Institute of Chemical Technology in Prague, Department of Food Preservation, Faculty of Food and Biochemical Technology (Czech Republic); Khun, J. [Institute of Chemical Technology in Prague, Department of Physics and Measurements, Faculty of Chemical Engineering (Czech Republic); Rusová, K. [Institute of Chemical Technology in Prague, Department of Food Preservation, Faculty of Food and Biochemical Technology (Czech Republic); Scholtz, V. [Institute of Chemical Technology in Prague, Department of Physics and Measurements, Faculty of Chemical Engineering (Czech Republic); Soušková, H. [Institute of Chemical Technology in Prague, Department of Computing and Control Engineering, Faculty of Chemical Engineering (Czech Republic)

    2013-09-15

    The inhibition effect of hydrogen peroxide aerosol, low-temperature plasma and their combinations has been studied on several micromycetes spores. The low-temperature plasma was generated in corona discharges in the open air apparatus with hydrogen peroxide aerosol. Micromycete spores were inoculated on the surface of agar plates, exposed solely to the hydrogen peroxide aerosol, corona discharge or their combination. After incubation the diameter of inhibition zone was measured. The solely positive corona discharge exhibits no inactivation effect, the solely negative corona discharge and solely hydrogen peroxide aerosol exhibit the inactivation effect, however their combinations exhibit to be much more effective. Low-temperature plasma and hydrogen peroxide aerosol present a possible alternative method of microbial decontamination of food, food packages or other thermolabile materials.

  15. Ideal laser-beam propagation through high-temperature ignition Hohlraum plasmas.

    Science.gov (United States)

    Froula, D H; Divol, L; Meezan, N B; Dixit, S; Moody, J D; Neumayer, P; Pollock, B B; Ross, J S; Glenzer, S H

    2007-02-23

    We demonstrate that a blue (3omega, 351 nm) laser beam with an intensity of 2 x 10(15) W cm(-2) propagates nearly within the original beam cone through a millimeter scale, T(e)=3.5 keV high density (n(e)=5 x 10(20) cm(-3)) plasma. The beam produced less than 1% total backscatter at these high temperatures and densities; the resulting transmission is greater than 90%. Scaling of the electron temperature in the plasma shows that the plasma becomes transparent for uniform electron temperatures above 3 keV. These results are consistent with linear theory thresholds for both filamentation and backscatter instabilities inferred from detailed hydrodynamic simulations. This provides a strong justification for current inertial confinement fusion designs to remain below these thresholds.

  16. Behavior of 23S metastable state He atoms in low-temperature recombining plasmas

    Science.gov (United States)

    Kajita, Shin; Tsujihara, Tadashi; Aramaki, Mitsutoshi; van der Meiden, Hennie; Oshima, Hiroshi; Ohno, Noriyasu; Tanaka, Hirohiko; Yasuhara, Ryo; Akiyama, Tsuyoshi; Fujii, Keisuke; Shikama, Taiichi

    2017-07-01

    We measured the electron density and temperature using laser Thomson scattering and metastable state (23S) of He atoms by laser absorption spectroscopy in the detached recombining plasmas in the divertor simulator NAGDIS-II. Using the measured electron density and temperature combined with the particle trajectory trace simulation, we discussed the behavior of the metastable state He atoms based on comparisons with the experimental results. It is shown that the metastable state atoms are mainly produced in the peripheral region of the plasma column, where the temperature is lower than the central part, and diffused in the vacuum vessel. It was shown that the 0D model is not valid and the transport of the metastable states is to be taken into account for the population distribution of He atoms in the detached plasmas.

  17. Plasma-enhanced mixing and flameholding in supersonic flow.

    Science.gov (United States)

    Firsov, Alexander; Savelkin, Konstantin V; Yarantsev, Dmitry A; Leonov, Sergey B

    2015-08-13

    The results of experimental study of plasma-based mixing, ignition and flameholding in a supersonic model combustor are presented in the paper. The model combustor has a length of 600 mm and cross section of 72 mm width and 60 mm height. The fuel is directly injected into supersonic airflow (Mach number M=2, static pressure P(st)=160-250 Torr) through wall orifices. Two series of tests are focused on flameholding and mixing correspondingly. In the first series, the near-surface quasi-DC electrical discharge is generated by flush-mounted electrodes at electrical power deposition of W(pl)=3-24 kW. The scope includes parametric study of ignition and flame front dynamics, and comparison of three schemes of plasma generation: the first and the second layouts examine the location of plasma generators upstream and downstream from the fuel injectors. The third pattern follows a novel approach of combined mixing/ignition technique, where the electrical discharge distributes along the fuel jet. The last pattern demonstrates a significant advantage in terms of flameholding limit. In the second series of tests, a long discharge of submicrosecond duration is generated across the flow and along the fuel jet. A gasdynamic instability of thermal cavity developed after a deposition of high-power density in a thin plasma filament promotes the air-fuel mixing. The technique studied in this work has weighty potential for high-speed combustion applications, including cold start/restart of scramjet engines and support of transition regime in dual-mode scramjet and at off-design operation. © 2015 The Author(s) Published by the Royal Society. All rights reserved.

  18. Enhanced Statistical Estimation of Air Temperature Incorporating Nighttime Light Data

    Directory of Open Access Journals (Sweden)

    Yunhao Chen

    2016-08-01

    Full Text Available Near surface air temperature (Ta is one of the most critical variables in climatology, hydrology, epidemiology, and environmental health. In situ measurements are not efficient for characterizing spatially heterogeneous Ta, while remote sensing is a powerful tool to break this limitation. This study proposes a mapping framework for daily mean Ta using an enhanced empirical regression method based on remote sensing data. It differs from previous studies in three aspects. First, nighttime light data is introduced as a predictor (besides land surface temperature, normalized difference vegetation index, impervious surface area, black sky albedo, normalized difference water index, elevation, and duration of daylight considering the urbanization-induced Ta increase over a large area. Second, independent components are extracted using principal component analysis considering the correlations among the above predictors. Third, a composite sinusoidal coefficient regression is developed considering the dynamic Ta-predictor relationship. This method was performed at 333 weather stations in China during 2001–2012. Evaluation shows overall mean error of −0.01 K, root mean square error (RMSE of 2.53 K, correlation coefficient (R2 of 0.96, and average uncertainty of 0.21 K. Model inter-comparison shows that this method outperforms six additional empirical regressions that have not incorporated nighttime light data or considered predictor independence or coefficient dynamics (by 0.18–2.60 K in RMSE and 0.00–0.15 in R2.

  19. EDITORIAL: The 9th Workshop on Frontiers in Low Temperature Plasma Diagnostics The 9th Workshop on Frontiers in Low Temperature Plasma Diagnostics

    Science.gov (United States)

    SAME ADDRESS--> Nader Sadeghi,

  1. Helium temperature measurements in a hot filament magnetic mirror plasma using high resolution Doppler spectroscopy

    Science.gov (United States)

    Knott, S.; McCarthy, P. J.; Ruth, A. A.

    2016-09-01

    Langmuir probe and spectroscopic diagnostics are used to routinely measure electron temperature and density over a wide operating range in a reconfigured Double Plasma device at University College Cork, Ireland. The helium plasma, generated through thermionic emission from a negatively biased tungsten filament, is confined by an axisymmetric magnetic mirror configuration using two stacks of NdFeB permanent magnets, each of length 20 cm and diameter 3 cm placed just outside the 15 mm water cooling jacket enclosing a cylindrical vacuum vessel of internal diameter 25 cm. Plasma light is analysed using a Fourier Transform-type Bruker spectrometer with a highest achievable resolution of 0.08 cm-1 . In the present work, the conventional assumption of room temperature ions in the analysis of Langmuir probe data from low temperature plasmas is examined critically using Doppler spectroscopy of the 468.6 nm He II line. Results for ion temperatures obtained from spectroscopic data for a variety of engineering parameters (discharge voltage, gas pressure and plasma current) will be presented.

  2. Pedestal Temperature Model for Type III ELMy H-mode Plasma

    International Nuclear Information System (INIS)

    Buangam, W.; Suwanna, S.; Onjun, T.; Poolyarat, N.; Picha, R.; Singhsomroje, W.

    2009-07-01

    Full text: It is widely known that the improved performance of H-mode plasma results mainly from a formation of the pedestal, which is a narrow region of strong pressure gradient near the edge of plasma. A predictive capability for the conditions at the top of the pedestal is important, especially for predictive simulations of future experiments. New models for predicting the temperature values at the top of the pedestal for type III ELMy H-mode plasma are developed by using two different approaches: a theory-based approaches and an empirical approach. For a theory-based approach, a model is developed based on the calculation of thermal energy in the pedestal region and on accepted scaling laws of energy confinement time. For an empirical model, a scaling law for pedestal temperature in terms of plasma controlled parameters, such as plasma current, magnetic field, heating power, is deduced from experimental data. Predictions from these models are compared with experimental data from the Pedestal International Database. Statistical quantities, such as Root-Mean Square Error (RMSE) and offset values, are computed to quantify the predictive capability of the models. It is found that the theory-based model predicts the pedestal temperature values moderately well yielding RMSE between 30% and 40%. The IPB98(y,3) scaling law yields with best agreement with RMSE of 30.4%. The empirical model predicts the pedestal temperature value with better agreement, yield RMSE of 25.9%

  3. Iron transport in a confined high-temperature plasma

    International Nuclear Information System (INIS)

    Demokan, O.; Waelbroeck, F.

    1981-06-01

    The neo-classical flux, GAMMAsub(n.c), of Fe XXIII is calculated for the experimental conditions produced in PLT by using the data on the iron density profiles and the plasma parameters. The actual flux of Fe XXIII, GAMMAsub(c.e), is then evaluated from the continuity equation, by using the same data. GAMMAsub(c.e) is on the average two orders of magnitude larger than GAMMAsub(n.c), the neo-classical prediction. These results are further tested by introducing the neo-classical coefficients which are multiplied by various anomaly factors into the continuity equation and solving for the density profile of Fe XXIII, using the experimental profiles of Fe XXII and Fe XXIV as given. The results of this section indicate that the first and the second terms in the neo-classical flux expression, GAMMAsub(n.c) = -D 1 (dn/dr) + D 2 n, should be multiplied approximately by the factors (100) and (25), respectively in order to yield the experimentally observed profile of Fe XXIII. (orig./HT)

  4. Enhanced Plasma Confinement in a Magnetic Well by Whistler Waves

    DEFF Research Database (Denmark)

    Balmashnov, A. A.; Juul Rasmussen, Jens

    1981-01-01

    The propagation of whistler waves in a magnetic field of mirror configuration is investigated experimentally. The strong interaction between waves and particles at the electron-cyclotron resonance leads to enhanced confinement in the magnetic well.......The propagation of whistler waves in a magnetic field of mirror configuration is investigated experimentally. The strong interaction between waves and particles at the electron-cyclotron resonance leads to enhanced confinement in the magnetic well....

  5. Cylindrical implosion to measure the radiative properties of high density and temperature plasmas

    International Nuclear Information System (INIS)

    Xu Yan; Rose, S.J.

    2000-01-01

    Cylindrical implosion is of great interest because of its excellent diagnostic access. The authors present one-dimensional numerical simulations to explore the plasma conditions that may be achieved. Combined with the numerical data, the development of Rayleigh-Taylor instabilities and Richtmyer-Meshkov instabilities in those targets are estimated. The authors found that it is possible to achieve a high density and temperature plasma with a relatively low temperature and density gradient using a cylindrical implosion directly-driven by a high-power laser

  6. Temporal evolutions of electron temperature and density of turbulently-heated tokamak plasmas in TRIAM-1

    Energy Technology Data Exchange (ETDEWEB)

    Hiraki, N; Nakamura, K; Nakamura, Y; Itoh, S [Kyushu Univ., Fukuoka (Japan). Research Inst. for Applied Mechanics

    1981-04-01

    The temporal evolution of the electron temperature and density are measured in a turbulent heating experiment in TRIAM-1. Skin-like profiles of the electron temperature and density are clearly observed. The anomality in the electrical resistivity of the plasma in this skin-layer is estimated, and the plasma heating in this skin-layer is regarded as being due to anomalous joule heating arising from this anomalous resistivity. The ratio of drift velocity to electron thermal velocity in the layer is also calculated, and it is shown that the conditions needed to make the current-driven ion-acoustic instability triggerable are satisfied.

  7. Finite-temperature random-phase approximation for spectroscopic properties of neon plasmas

    International Nuclear Information System (INIS)

    Colgan, J.; Collins, L. A.; Fontes, C. J.; Csanak, G.

    2007-01-01

    A finite-temperature random-phase approximation (FTRPA) is applied to calculate oscillator strengths for excitations in hot and dense plasmas. Application of the FTRPA provides a convenient, self-consistent method with which to explore coupled-channel effects of excited electrons in a dense plasma. We present FTRPA calculations that include coupled-channel effects. The inclusion of these effects is shown to cause significant differences in the oscillator strength for a prototypical case of 1 P excitation in neon when compared with single-channel and with average-atom calculations. Trends as a function of temperature and density are also discussed

  8. Green frequency-doubled laser-beam propagation in high-temperature hohlraum plasmas.

    Science.gov (United States)

    Niemann, C; Berger, R L; Divol, L; Froula, D H; Jones, O; Kirkwood, R K; Meezan, N; Moody, J D; Ross, J; Sorce, C; Suter, L J; Glenzer, S H

    2008-02-01

    We demonstrate propagation and small backscatter losses of a frequency-doubled (2omega) laser beam interacting with inertial confinement fusion hohlraum plasmas. The electron temperature of 3.3 keV, approximately a factor of 2 higher than achieved in previous experiments with open geometry targets, approaches plasma conditions of high-fusion yield hohlraums. In this new temperature regime, we measure 2omega laser-beam transmission approaching 80% with simultaneous backscattering losses of less than 10%. These findings suggest that good laser coupling into fusion hohlraums using 2omega light is possible.

  9. Pattern formation and filamentation in low temperature, magnetized plasmas - a numerical approach

    Science.gov (United States)

    Menati, Mohamad; Konopka, Uwe; Thomas, Edward

    2017-10-01

    In low-temperature discharges under the influence of high magnetic field, pattern and filament formation in the plasma has been reported by different groups. The phenomena present themselves as bright plasma columns (filaments) oriented parallel to the magnetic field lines at high magnetic field regime. The plasma structure can filament into different shapes from single columns to spiral and bright rings when viewed from the top. In spite of the extensive experimental observations, the observed effects lack a detailed theoretical and numerical description. In an attempt to numerically explain the plasma filamentation, we present a simplified model for the plasma discharge and power deposition into the plasma. Based on the model, 2-D and 3-D codes are being developed that solve Poisson's equation along with the fluid equations to obtain a self-consistent description of the plasma. The model and preliminary results applied to the specific plasma conditions will be presented. This work was supported by the US Dept. of Energy and NSF, DE-SC0016330, PHY-1613087.

  10. Optical and electrical characteristics of plasma enhanced chemical vapor deposition boron carbonitride thin films derived from N-trimethylborazine precursor

    Energy Technology Data Exchange (ETDEWEB)

    Sulyaeva, Veronica S., E-mail: veronica@niic.nsc.ru [Department of Functional Materials Chemistry, Nikolaev Institute of Inorganic Chemistry SB RAS, Novosibirsk 630090 (Russian Federation); Kosinova, Marina L.; Rumyantsev, Yurii M.; Kuznetsov, Fedor A. [Department of Functional Materials Chemistry, Nikolaev Institute of Inorganic Chemistry SB RAS, Novosibirsk 630090 (Russian Federation); Kesler, Valerii G. [Laboratory of Physical Principles for Integrated Microelectronics, Rzhanov Institute of Semiconductor Physics SB RAS, Novosibirsk 630090 (Russian Federation); Kirienko, Viktor V. [Laboratory of Nonequilibrium Semiconductors Systems, Rzhanov Institute of Semiconductor Physics SB RAS, Novosibirsk 630090 (Russian Federation)

    2014-05-02

    Thin BC{sub x}N{sub y} films have been obtained by plasma enhanced chemical vapor deposition using N-trimethylborazine as a precursor. The films were deposited on Si(100) and fused silica substrates. The grown films were characterized by ellipsometry, Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray energy dispersive spectroscopy, X-ray photoelectron spectroscopy, spectrophotometry, capacitance–voltage and current–voltage measurements. The deposition parameters, such as substrate temperature (373–973 K) and gas phase composition were varied. Low temperature BC{sub x}N{sub y} films were found to be high optical transparent layers in the range of 300–2000 nm, the transmittance as high as 93% has been achieved. BC{sub x}N{sub y} layers are dielectrics with dielectric constant k = 2.2–8.9 depending on the synthesis conditions. - Highlights: • Thin BC{sub x}N{sub y} films have been obtained by plasma enhanced chemical vapor deposition. • N-trimethylborazine was used as a precursor. • Low temperature BC{sub x}N{sub y} films were found to be high optical transparent layers (93%). • BC{sub x}N{sub y} layers are dielectrics with dielectric constant k = 2.2–8.9.

  11. Optical and electrical characteristics of plasma enhanced chemical vapor deposition boron carbonitride thin films derived from N-trimethylborazine precursor

    International Nuclear Information System (INIS)

    Sulyaeva, Veronica S.; Kosinova, Marina L.; Rumyantsev, Yurii M.; Kuznetsov, Fedor A.; Kesler, Valerii G.; Kirienko, Viktor V.

    2014-01-01

    Thin BC x N y films have been obtained by plasma enhanced chemical vapor deposition using N-trimethylborazine as a precursor. The films were deposited on Si(100) and fused silica substrates. The grown films were characterized by ellipsometry, Fourier transform infrared spectroscopy, scanning electron microscopy, X-ray energy dispersive spectroscopy, X-ray photoelectron spectroscopy, spectrophotometry, capacitance–voltage and current–voltage measurements. The deposition parameters, such as substrate temperature (373–973 K) and gas phase composition were varied. Low temperature BC x N y films were found to be high optical transparent layers in the range of 300–2000 nm, the transmittance as high as 93% has been achieved. BC x N y layers are dielectrics with dielectric constant k = 2.2–8.9 depending on the synthesis conditions. - Highlights: • Thin BC x N y films have been obtained by plasma enhanced chemical vapor deposition. • N-trimethylborazine was used as a precursor. • Low temperature BC x N y films were found to be high optical transparent layers (93%). • BC x N y layers are dielectrics with dielectric constant k = 2.2–8.9

  12. Current fundamental science challenges in low temperature plasma science that impact energy security and international competitiveness

    Science.gov (United States)

    Hebner, Greg

    2010-11-01

    Products and consumer goods that utilize low temperature plasmas at some point in their creation touch and enrich our lives on almost a continuous basis. Examples are many but include the tremendous advances in microelectronics and the pervasive nature of the internet, advanced material coatings that increase the strength and reliability of products from turbine engines to potato chip bags, and the recent national emphasis on energy efficient lighting and compact fluorescent bulbs. Each of these products owes their contributions to energy security and international competiveness to fundamental research investments. However, it would be a mistake to believe that the great commercial success of these products implies a robust understanding of the complicated interactions inherent in plasma systems. Rather, current development of the next generation of low temperature plasma enabled products and processes is clearly exposing a new set of exciting scientific challenges that require leaps in fundamental understanding and interdisciplinary research teams. Emerging applications such as liquid-plasma systems to improve water quality and remediate hazardous chemicals, plasma-assisted combustion to increase energy efficiency and reduce emissions, and medical applications promise to improve our lives and the environment only if difficult science questions are solved. This talk will take a brief look back at the role of low temperature plasma science in enabling entirely new markets and then survey the next generation of emerging plasma applications. The emphasis will be on describing the key science questions and the opportunities for scientific cross cutting collaborations that underscore the need for increased outreach on the part of the plasma science community to improve visibility at the federal program level. This work is supported by the DOE, Office of Science for Fusion Energy Sciences, and Sandia National Laboratories, a multi-program laboratory managed and operated

  13. High-speed three-dimensional plasma temperature determination of axially symmetric free-burning arcs

    International Nuclear Information System (INIS)

    Bachmann, B; Ekkert, K; Bachmann, J-P; Marques, J-L; Schein, J; Kozakov, R; Gött, G; Schöpp, H; Uhrlandt, D

    2013-01-01

    In this paper we introduce an experimental technique that allows for high-speed, three-dimensional determination of electron density and temperature in axially symmetric free-burning arcs. Optical filters with narrow spectral bands of 487.5–488.5 nm and 689–699 nm are utilized to gain two-dimensional spectral information of a free-burning argon tungsten inert gas arc. A setup of mirrors allows one to image identical arc sections of the two spectral bands onto a single camera chip. Two-different Abel inversion algorithms have been developed to reconstruct the original radial distribution of emission coefficients detected with each spectral window and to confirm the results. With the assumption of local thermodynamic equilibrium we calculate emission coefficients as a function of temperature by application of the Saha equation, the ideal gas law, the quasineutral gas condition and the NIST compilation of spectral lines. Ratios of calculated emission coefficients are compared with measured ones yielding local plasma temperatures. In the case of axial symmetry the three-dimensional plasma temperature distributions have been determined at dc currents of 100, 125, 150 and 200 A yielding temperatures up to 20000 K in the hot cathode region. These measurements have been validated by four different techniques utilizing a high-resolution spectrometer at different positions in the plasma. Plasma temperatures show good agreement throughout the different methods. Additionally spatially resolved transient plasma temperatures have been measured of a dc pulsed process employing a high-speed frame rate of 33000 frames per second showing the modulation of the arc isothermals with time and providing information about the sensitivity of the experimental approach. (paper)

  14. Oxygen Barrier Coating Deposited by Novel Plasma-enhanced Chemical Vapor Deposition

    DEFF Research Database (Denmark)

    Jiang, Juan; Benter, M.; Taboryski, Rafael Jozef

    2010-01-01

    We report the use of a novel plasma-enhanced chemical vapor deposition chamber with coaxial electrode geometry for the SiOx deposition. This novel plasma setup exploits the diffusion of electrons through the inner most electrode to the interior samples space as the major energy source. This confi......We report the use of a novel plasma-enhanced chemical vapor deposition chamber with coaxial electrode geometry for the SiOx deposition. This novel plasma setup exploits the diffusion of electrons through the inner most electrode to the interior samples space as the major energy source...... effect of single-layer coatings deposited under different reaction conditions was studied. The coating thickness and the carbon content in the coatings were found to be the critical parameters for the barrier property. The novel barrier coating was applied on different polymeric materials...

  15. Temperature diagnostics of a non-thermal plasma jet at atmospheric pressure

    Science.gov (United States)

    Schäfer, Jan

    2013-09-01

    The study reflects the concept of the temperature as a physical quantity resulting from the second thermodynamic law. The reliability of different approaches of the temperature diagnostics of open non-equilibrium systems is discussed using examples of low temperature atmospheric pressure discharges. The focus of this work is a miniaturized non-thermal atmospheric pressure plasma jet for local surface treatment at ambient atmosphere. The micro-discharge is driven with a capacitively coupled radio frequency electric field at 27.12 MHz and fed with argon at rates of about 1 slm through the capillary with an inner diameter of 4 mm. The discharge consists of several contracted filaments with diameter around 300 μm which are rotating azimuthally in the capillary in a self-organized manner. While the measured temperatures of the filament core exceed 700 K, the heat impact on a target below the plasma jet remains limited leading to target temperatures below 400 K. Different kinds of temperatures and energy transport processes are proposed and experimentally investigated. Nevertheless, a reliable and detailed temperature diagnostics is a challenge. We report on a novel diagnostics approach for the spatially and temporally resolved measurement of the gas temperature based on the optical properties of the plasma. Laser Schlieren Deflectometry is adapted to explore temperature profiles of filaments and their behaviour. In parallel, the method demonstrates a fundamental Fermat's principle of minimal energy. Information acquired with this method plays an important role for the optimization of local thin film deposition and surface functionalization by means of the atmospheric pressure plasma jet. The work was supported in part by the Deutsche Forschungsgemeinschaft within SFB-TR 24.

  16. Profile correction to electron temperature and enhancement factor in soft-x-ray pulse-height-analysis measurements in tokamaks

    International Nuclear Information System (INIS)

    Sesnic, S.; Diesso, M.; Hill, K.; Holland, A.; Pohl, F.

    1988-01-01

    Because soft-x-ray pulse-height-analysis spectra contain chordal information, the electron temperature and the radiation intensity (enhancement factor) measurements do not represent the local values. The correction factors for the electron temperature and the enhancement factor as a function of the temperature and density profile parameters and the energy are obtained. The spectrum distortion due to pulse pileup effects is also evaluated. A set of curves is given from which the distortion of the spectrum can be obtained if the electron temperature, the Be filter thickness, and the electronic parameters of the acquisition system are known. PG 1810,1812 ID 131801CON N X-ray diagnostics TT Profile correction to electron temperature and enhancement factor in soft-x-ray pulse-height-analysis measurements in tokamaks AU S. Sesnic, M. Diesso, K. Hill, and A. Holland LO Princeton University, Plasma Physics Laboratory, P.O. Box 451, Princeton, New Jersey 08543 AU F. Pohl LO Max-Planck Institut fuer Plasmaphysik, 8046-Garching, Federal Republic of Germany SD (Presented on 16 March 1988) AB Because soft-x-ray pulse-height-analysis spectra contain chordal information, the electron temperature and the radiation intensity (enhancement factor) measurements do not represent the local values. The correction factors for the electron temperature and the enhancement factor as a function of the temperature and density profile parameters and the energy are obtained. The spectrum distortion due to pulse pileup effects is also evaluated. A set of curves is given from which the distortion of the spectrum can be obtained if the electron tempe

  17. Electron energy distribution functions and transport coefficients relevant for air plasmas in the troposphere: impact of humidity and gas temperature

    Energy Technology Data Exchange (ETDEWEB)

    Gordillo-Vazquez, F J [Instituto de Astrofisica de Andalucia (IAA), CSIC, PO Box 3004, 18080 Granada (Spain); Donko, Z [Research Institute for Solid State Physics and Optics, H-1525 Budapest, PO Box, 49 (Hungary)

    2009-08-15

    A Boltzmann and Monte Carlo analysis of the electron energy distribution function (EEDF) and transport coefficients for air plasmas is presented for the conditions of the Earth troposphere where some transient luminous events (TLEs) such as blue jets, blue starters and gigantic jets have been observed. According to recent model results (Minschwaner et al 2004 J. Climate 17 1272) supported by the halogen occultation experiment, the relative humidity of the atmospheric air between 0 and 15 km can change between 15% and 100% depending on the altitude investigated and the ground temperature. The latter results cover a region of latitudes between -25 deg. S and +25 deg. N, that is, the Earth tropical region where lightning and TLE activity is quite high. The calculations shown here suggest that the relative humidity has a clear impact on the behaviour of the EEDF and magnitude of the transport coefficients of air plasmas at ground (0 km) and room temperature conditions (293 K). At higher altitudes (11 and 15 km), the influence of the relative humidity is negligible when the values of the gas temperature are assumed to be the 'natural' ones corresponding to those altitudes, that is, {approx}215 K (at 11 km) and {approx}198 K (at 15 km). However, it is found that a small enhancement (of maximum 100 K) in the background gas temperature (that could be reasonably associated with the TLE activity) would lead to a remarkable impact of the relative humidity on the EEDF and transport coefficients of air plasmas under the conditions of blue jets, blue starters and gigantic jets at 11 and 15 km. The latter effects are visible for relatively low reduced electric fields (E/N {<=} 25 Td) that could be controlling the afterglow kinetics of the air plasmas generated by TLEs. However, for much higher fields such as, for instance, 400 Td (representative of the fields in the streamer coronas and lightning leaders), the impact of increasing the relative humidity and gas

  18. Electron energy distribution functions and transport coefficients relevant for air plasmas in the troposphere: impact of humidity and gas temperature

    International Nuclear Information System (INIS)

    Gordillo-Vazquez, F J; Donko, Z

    2009-01-01

    A Boltzmann and Monte Carlo analysis of the electron energy distribution function (EEDF) and transport coefficients for air plasmas is presented for the conditions of the Earth troposphere where some transient luminous events (TLEs) such as blue jets, blue starters and gigantic jets have been observed. According to recent model results (Minschwaner et al 2004 J. Climate 17 1272) supported by the halogen occultation experiment, the relative humidity of the atmospheric air between 0 and 15 km can change between 15% and 100% depending on the altitude investigated and the ground temperature. The latter results cover a region of latitudes between -25 deg. S and +25 deg. N, that is, the Earth tropical region where lightning and TLE activity is quite high. The calculations shown here suggest that the relative humidity has a clear impact on the behaviour of the EEDF and magnitude of the transport coefficients of air plasmas at ground (0 km) and room temperature conditions (293 K). At higher altitudes (11 and 15 km), the influence of the relative humidity is negligible when the values of the gas temperature are assumed to be the 'natural' ones corresponding to those altitudes, that is, ∼215 K (at 11 km) and ∼198 K (at 15 km). However, it is found that a small enhancement (of maximum 100 K) in the background gas temperature (that could be reasonably associated with the TLE activity) would lead to a remarkable impact of the relative humidity on the EEDF and transport coefficients of air plasmas under the conditions of blue jets, blue starters and gigantic jets at 11 and 15 km. The latter effects are visible for relatively low reduced electric fields (E/N ≤ 25 Td) that could be controlling the afterglow kinetics of the air plasmas generated by TLEs. However, for much higher fields such as, for instance, 400 Td (representative of the fields in the streamer coronas and lightning leaders), the impact of increasing the relative humidity and gas temperature is only slightly

  19. Collaborative Research. Fundamental Science of Low Temperature Plasma-Biological Material Interactions

    Energy Technology Data Exchange (ETDEWEB)

    Graves, David Barry [Univ. California, Berkeley, CA (United States); Oehrlein, Gottlieb [Univ. of Maryland, College Park, MD (United States)

    2014-09-01

    Low temperature plasma (LTP) treatment of biological tissue is a promising path toward sterilization of bacteria due to its versatility and ability to operate under well-controlled and relatively mild conditions. The present collaborative research of an interdisciplinary team of investigators at University of Maryland, College Park (UMD), and University of California, Berkeley (UCB) focused on establishing our knowledge based with regard to low temperature plasma-induced chemical modifications in biomolecules that result in inactivation due to various plasma species, including ions, reactive radicals, and UV/VUV photons. The overall goals of the project were to identify and quantify the mechanisms by which low and atmospheric pressure plasma deactivates endotoxic biomolecules. Additionally, we wanted to understand the mechanism by which atmospheric pressure plasmas (APP) modify surfaces and how these modifications depend on the interaction of APP with the environment. Various low pressure plasma sources, a vacuum beam system and several atmospheric pressure plasma sources were used to accomplish this. In our work we elucidated for the first time the role of ions, VUV photons and radicals in biological deactivation of representative biomolecules, both in a UHV beam system and an inductively coupled, low pressure plasma system, and established the associated atomistic biomolecule changes. While we showed that both ions and VUV photons can be very efficient in deactivation of biomolecules, significant etching and/or deep modification (~200 nm) accompanied these biological effects. One of the most important findings in this work is the significant radical-induced deactivation and surface modification can occur with minimal etching. However, if radical fluxes and corresponding etch rates are relatively high, for example at atmospheric pressure, endotoxic biomolecule film inactivation may require near-complete removal of the film. These findings motivated further work at

  20. Nanostructure and optical properties of CeO{sub 2} thin films obtained by plasma-enhanced chemical vapor deposition

    Energy Technology Data Exchange (ETDEWEB)

    Barreca, D.; Bruno, G.; Gasparotto, A.; Losurdo, M.; Tondello, E

    2003-12-15

    In the present study, Spectroscopic Ellipsometry (SE) is used to investigate the interrelations between nanostructure and optical properties of CeO{sub 2} thin films deposited by Plasma-Enhanced Chemical Vapor Deposition (PE-CVD). The layers were synthesized in Ar and Ar-O{sub 2} plasmas on Si(100) substrates at temperatures lower than 300 deg. C. Both the real and imaginary parts of the complex dielectric functions and, subsequently, the optical constants of the films are derived up to 6.0 eV photon energy. Particular attention is devoted to the influence of synthesis conditions and sample properties on the optical response, taking into account the effects of surface roughness and SiO{sub 2} interface layer on Si.

  1. Spectroscopic measurements of plasma temperatures and electron number density in a uranium hollow cathode discharge lamp

    International Nuclear Information System (INIS)

    Shah, M.L.; Suri, B.M.; Gupta, G.P.

    2015-01-01

    The HCD (Hollow Cathode Discharge) lamps have been used as a source of free atoms of any metal, controllable by direct current in the lamp. The plasma parameters including neutral species temperature, atomic excitation temperature and electron number density in a see-through type, homemade uranium hollow cathode discharge lamp with neon as a buffer gas have been investigated using optical emission spectroscopic techniques. The neutral species temperature has been measured using the Doppler broadening of a neon atomic spectral line. The atomic excitation temperature has been measured using the Boltzmann plot method utilizing uranium atomic spectral lines. The electron number density has been determined from the Saha-Boltzmann equation utilizing uranium atomic and ionic spectral lines. To the best of our knowledge, all these three plasma parameters are simultaneously measured for the first time in a uranium hollow cathode discharge lamp

  2. Plasma flow reactor for steady state monitoring of physical and chemical processes at high temperatures.

    Science.gov (United States)

    Koroglu, Batikan; Mehl, Marco; Armstrong, Michael R; Crowhurst, Jonathan C; Weisz, David G; Zaug, Joseph M; Dai, Zurong; Radousky, Harry B; Chernov, Alex; Ramon, Erick; Stavrou, Elissaios; Knight, Kim; Fabris, Andrea L; Cappelli, Mark A; Rose, Timothy P

    2017-09-01

    We present the development of a steady state plasma flow reactor to investigate gas phase physical and chemical processes that occur at high temperature (1000 flow injector). We have modeled the system using computational fluid dynamics simulations that are bounded by measured temperatures. In situ line-of-sight optical emission and absorption spectroscopy have been used to determine the structures and concentrations of molecules formed during rapid cooling of reactants after they pass through the plasma. Emission spectroscopy also enables us to determine the temperatures at which these dynamic processes occur. A sample collection probe inserted from the open end of the reactor is used to collect condensed materials and analyze them ex situ using electron microscopy. The preliminary results of two separate investigations involving the condensation of metal oxides and chemical kinetics of high-temperature gas reactions are discussed.

  3. Enhancement of the Laser Transmission Weldability between Polyethylene and Polyoxymethylene by Plasma Surface Treatment

    Directory of Open Access Journals (Sweden)

    Huixia Liu

    2017-12-01

    Full Text Available Due to their large compatibility difference, polyethylene (PE and polyoxymethylene (POM cannot be welded together by laser transmission welding. In this study, PE and POM are pretreated using plasma that significantly enhances their laser transmission welding strength. To understand the mechanism underlying the laser welding strength enhancement, surface modification is analyzed using contact angle measurements, atomic force microscopy (AFM, optical microscopy, and X-ray photoelectron spectroscopy (XPS. Characterization results show that the plasma surface treatment improves the surface free energy, significantly enhancing the wettability of the materials. The increase in surface roughness and the generation of homogeneous bubbles contribute to the formation of mechanical micro-interlocking. The oxygen-containing groups introduced by the oxygen plasma treatment improve the compatibility of PE and POM, and facilitate the diffusion and entanglement of molecular chains and the formation of van der Waals force.

  4. Rotating structures in low temperature magnetized plasmas - Insight from particle simulations

    Directory of Open Access Journals (Sweden)

    Jean-Pierre eBoeuf

    2014-12-01

    Full Text Available The EXB configuration of various low temperature plasma devices is often responsible for the formation of rotating structures and instabilities leading to anomalous electron transport across the magnetic field. In these devices, electrons are strongly magnetized while ions are weakly or not magnetized and this leads to specific physical phenomena that are not present in fusion plasmas where both electrons and ions are strongly magnetized. In this paper we describe basic phenomena involving rotating plasma structures in simple configurations of low temperature EXB plasma devices on the basis of PIC-MCC (Particle-In-Cell Monte Carlo Collisions simulations. We focus on three examples: rotating electron vortices and rotating spokes in cylindrical magnetrons, and azimuthal electron-cyclotron drift instability in Hall thrusters. The simulations are not intended to give definite answers to the many physics issues related to low temperature EXB plasma devices but are used to illustrate and discuss some of the basic questions that need further studies.

  5. Enhanced electromagnetic emission from plasmas containing positive dust grains and electrons

    International Nuclear Information System (INIS)

    Shukla, P.K.; Shukla, Nitin; Stenflo, L.

    2007-01-01

    Large amplitude high-frequency (HF) electromagnetic (EM) waves can scatter off dust-acoustic waves in plasmas containing positive dust grains and electrons, and can thus be responsible for HF enhanced electromagnetic emissions (EEE). An expression for the ensemble average of the squared HF-EEE vector potential is therefore derived, following the standard parametric interaction formalism and adopting the Rostoker superposition principle. The results should be useful for deducing the dust plasma parameters (e.g. the dust number density and dust charge) in situ, and HF intense EM beams can thus be used for diagnosis of positive dust-electron plasmas in space and laboratories

  6. ENHANCED MODELING OF REMOTELY SENSED ANNUAL LAND SURFACE TEMPERATURE CYCLE

    Directory of Open Access Journals (Sweden)

    Z. Zou

    2017-09-01

    Full Text Available Satellite thermal remote sensing provides access to acquire large-scale Land surface temperature (LST data, but also generates missing and abnormal values resulting from non-clear-sky conditions. Given this limitation, Annual Temperature Cycle (ATC model was employed to reconstruct the continuous daily LST data over a year. The original model ATCO used harmonic functions, but the dramatic changes of the real LST caused by the weather changes remained unclear due to the smooth sine curve. Using Aqua/MODIS LST products, NDVI and meteorological data, we proposed enhanced model ATCE based on ATCO to describe the fluctuation and compared their performances for the Yangtze River Delta region of China. The results demonstrated that, the overall root mean square errors (RMSEs of the ATCE was lower than ATCO, and the improved accuracy of daytime was better than that of night, with the errors decreased by 0.64 K and 0.36 K, respectively. The improvements of accuracies varied with different land cover types: the forest, grassland and built-up areas improved larger than water. And the spatial heterogeneity was observed for performance of ATC model: the RMSEs of built-up area, forest and grassland were around 3.0 K in the daytime, while the water attained 2.27 K; at night, the accuracies of all types significantly increased to similar RMSEs level about 2 K. By comparing the differences between LSTs simulated by two models in different seasons, it was found that the differences were smaller in the spring and autumn, while larger in the summer and winter.

  7. Effect of two-temperature electrons distribution on an electrostatic plasma sheath

    International Nuclear Information System (INIS)

    Ou, Jing; Xiang, Nong; Gan, Chunyun; Yang, Jinhong

    2013-01-01

    A magnetized collisionless plasma sheath containing two-temperature electrons is studied using a one-dimensional model in which the low-temperature electrons are described by Maxwellian distribution (MD) and high-temperature electrons are described by truncated Maxwellian distribution (TMD). Based on the ion wave approach, a modified sheath criterion including effect of TMD caused by high-temperature electrons energy above the sheath potential energy is established theoretically. The model is also used to investigate numerically the sheath structure and energy flux to the wall for plasmas parameters of an open divertor tokamak-like. Our results show that the profiles of the sheath potential, two-temperature electrons and ions densities, high-temperature electrons and ions velocities as well as the energy flux to the wall depend on the high-temperature electrons concentration, temperature, and velocity distribution function associated with sheath potential. In addition, the results obtained in the high-temperature electrons with TMD as well as with MD sheaths are compared for the different sheath potential

  8. Transport and fluctuations in high temperature spheromak plasmas

    International Nuclear Information System (INIS)

    McLean, H.S.; Wood, R.D.; Cohen, B.I.; Hooper, E.B.; Hill, D.N.; Moller, J.M.; Romero-Talamas, C.; Woodruff, S.

    2006-01-01

    Higher electron temperature (T e >350 eV) and reduced electron thermal diffusivity (χ e 2 /s) is achieved in the Sustained Spheromak Physics Experiment (SSPX) by increasing the discharge current=I gun and gun bias flux=ψ gun in a prescribed manner. The internal current and q=safety factor profile derived from equilibrium reconstruction as well as the measured magnetic fluctuation amplitude can be controlled by programming the ratio λ gun =μ 0 I gun /ψ gun . Varying λ gun above and below the minimum energy eigenvalue=λ FC of the flux conserver (∇xB-vector=λ FC B-vector) varies the q profile and produces the m/n=poloidal/toroidal magnetic fluctuation mode spectrum expected from mode-rational surfaces with q=m/n. The highest T e is measured when the gun is driven with λ gun slightly less than λ FC , producing low fluctuation amplitudes ( e as T e increases, differing from Bohm or open field line transport models where χ e increases with T e . Detailed resistive magnetohydrodynamic simulations with the NIMROD code support the analysis of energy confinement in terms of the causal link with the q profile, magnetic fluctuations associated with low-order mode-rational surfaces, and the quality of magnetic surfaces

  9. Sheath and heat flow of a two-electron-temperature plasma in the presence of electron emission

    International Nuclear Information System (INIS)

    Sato, Kunihiro; Miyawaki, Fujio

    1992-01-01

    The electrostatic sheath and the heat flow of a two-electron-temperature plasma in the presence of electron emission are investigated analytically. It is shown that the energy flux is markedly enhanced to a value near the electron free-flow energy flux as a result of considerable reduction of the sheath potential due to electron emission if the fraction of hot electrons at the sheath edge is much smaller than one. If the hot- to cold-electron temperature ratio is of the order of ten and the hot electron density is comparable to the cold electron density, the action of the sheath as a thermal insulator is improved as a result of suppression of electron emission due to the space-charge effect of hot electrons. (author)

  10. Influence of the choice of internal temperatures on the composition of CxHyOzNt plasmas out of thermodynamic equilibrium: Application to CH2 plasma

    International Nuclear Information System (INIS)

    Koalaga, Zacharie

    2002-01-01

    The purpose of this paper is to study the influence of the choice of internal temperatures on the composition of C x H y O z N t plasmas out of thermodynamic equilibrium. The numerical calculation is specially performed for CH 2 plasma in the pressure range 0.1-1 MPa and for the electron temperature range 5000-30 000 K. Precisely, the investigation of this plasma allows one to show that the choice of internal temperatures can have more influence on plasma composition than the choice of the form of the two-temperature Saha and Guldberg-Waage laws. Indeed, for one of the supposed hypotheses, it is observed that the two forms of the two-temperature system used here can give the same equilibrium composition by uncoupling the excitation temperature of the diatomic and the monatomic species. Great attention must then be given to the adopted hypothesis for internal temperature and not only to the form of the two temperature system used. An accurate comparison between the two models requires the measurement of plasma parameters such as the various internal temperatures and the species concentration. Therefore, we have also carried out an analysis of the potential experimental diagnostics of these plasma parameters. Such diagnostics can help to test and validate theoretical models

  11. Studies of the impurity pellet ablation in the high-temperature plasma of magnetic confinement devices

    International Nuclear Information System (INIS)

    Sergeev, V. Yu.; Bakhareva, O. A.; Kuteev, B. V.; Tendler, M.

    2006-01-01

    The ablation of impurity pellets in tokamak and stellarator plasmas is investigated. Different mechanisms for shielding the heat fluxes from the surrounding plasma to the pellet surface are discussed. A model for impurity pellet ablation is developed that can account for both neutral and electrostatic shielding. It is shown that the experimental values of the impurity pellet ablation rate are well described by the neutral gas shielding model over a wide range of plasma temperatures and densities. Taking into account the electrostatic shielding leads to worse agreement between the predictions of the model and the experimental data; this result still remains unclear. Scaling laws are obtained that allow one to estimate the local ablation rate of impurity pellets made of various materials over a wide range of plasma parameters in the neutral gas shielding model

  12. X-ray spectroscopic diagnostics of high-temperature dense plasmas created in different gaseous media

    International Nuclear Information System (INIS)

    Skobelev, I.Y.; Dyakin, V.M.; Faenov, A.Y.

    1997-01-01

    The investigations of emission x-ray spectra of multicharged ions of some chemical elements (S, F, Ar, Fr, O) have been carried out. These atoms are contained in gases and consequently can be used as diagnostic elements in a dense plasma focus experiments. The investigations were done in the dense high-temperature plasma (N e ∼ 10 21 cm -3 , T e ∼ 500 eV) created by laser heating of high-pressure gas puff targets, and X-ray spectrographs with a spherically bent mica crystals were used for spectra observations. Some new spectroscopic results (line identifications, high-precision wavelength measurements) have been obtained and have been applied to determine a spatial distribution of plasma parameters. It is shown that spectroscopic techniques used is a very suitable tool for studies of a plasma with complicated spatial structure

  13. Ion acoustic solitons in a plasma with two-temperature kappa-distributed electrons

    International Nuclear Information System (INIS)

    Baluku, T. K.; Hellberg, M. A.

    2012-01-01

    Existence domains and characteristics of ion acoustic solitons are studied in a two-temperature electron plasma with both electron components being kappa-distributed, as found in Saturn's magnetosphere. As is the case for double-Boltzmann electrons, solitons of both polarities can exist over restricted ranges of fractional hot electron density ratio for this plasma model. Low κ values, which indicate increased suprathermal particles in the tail of the distribution, yield a smaller domain in the parameter space of hot density fraction and normalized soliton velocity (f, M), over which both soliton polarities are supported for a given plasma composition (the coexistence region). For some density ratios that support coexistence, solitons occur even at the lowest (critical) Mach number (i.e., at the acoustic speed), as found recently for a number of other plasma models. Like Maxwellians, low-κ distributions also support positive potential double layers over a narrow range of low fractional cool electron density (<10%).

  14. A simple method to deposit palladium doped SnO2 thin films using plasma enhanced chemical vapor deposition technique

    International Nuclear Information System (INIS)

    Kim, Young Soon; Wahab, Rizwan; Shin, Hyung-Shik; Ansari, S. G.; Ansari, Z. A.

    2010-01-01

    This work presents a simple method to deposit palladium doped tin oxide (SnO 2 ) thin films using modified plasma enhanced chemical vapor deposition as a function of deposition temperature at a radio frequency plasma power of 150 W. Stannic chloride (SnCl 4 ) was used as precursor and oxygen (O 2 , 100 SCCM) (SCCM denotes cubic centimeter per minute at STP) as reactant gas. Palladium hexafluroacetyleacetonate (Pd(C 5 HF 6 O 2 ) 2 ) was used as a precursor for palladium. Fine granular morphology was observed with tetragonal rutile structure. A peak related to Pd 2 Sn is observed, whose intensity increases slightly with deposition temperature. Electrical resistivity value decreased from 8.6 to 0.9 mΩ cm as a function of deposition temperature from 400 to 600 deg. C. Photoelectron peaks related to Sn 3d, Sn 3p3, Sn 4d, O 1s, and C 1s were detected with varying intensities as a function of deposition temperature.

  15. A reduced model for ion temperature gradient turbulent transport in helical plasmas

    International Nuclear Information System (INIS)

    Nunami, M.; Watanabe, T.-H.; Sugama, H.

    2013-07-01

    A novel reduced model for ion temperature gradient (ITG) turbulent transport in helical plasmas is presented. The model enables one to predict nonlinear gyrokinetic simulation results from linear gyrokinetic analyses. It is shown from nonlinear gyrokinetic simulations of the ITG turbulence in helical plasmas that the transport coefficient can be expressed as a function of the turbulent fluctuation level and the averaged zonal flow amplitude. Then, the reduced model for the turbulent ion heat diffusivity is derived by representing the nonlinear turbulent fluctuations and zonal flow amplitude in terms of the linear growth rate of the ITG instability and the linear response of the zonal flow potentials. It is confirmed that the reduced transport model results are in good agreement with those from nonlinear gyrokinetic simulations for high ion temperature plasmas in the Large Helical Device. (author)

  16. MOSS spectroscopic camera for imaging time resolved plasma species temperature and flow speed

    International Nuclear Information System (INIS)

    Michael, Clive; Howard, John

    2000-01-01

    A MOSS (Modulated Optical Solid-State) spectroscopic camera has been devised to monitor the spatial and temporal variations of temperatures and flow speeds of plasma ion species, the Doppler broadening measurement being made of spectroscopic lines specified. As opposed to a single channel MOSS spectrometer, the camera images light from plasma onto an array of light detectors, being mentioned 2D imaging of plasma ion temperatures and flow speeds. In addition, compared to a conventional grating spectrometer, the MOSS camera shows an excellent light collecting performance which leads to the improvement of signal to noise ratio and of time resolution. The present paper first describes basic items of MOSS spectroscopy, then follows MOSS camera with an emphasis on the optical system of 2D imaging. (author)

  17. Measurement of plasma potential and electron temperature by ball-pen probes in RFX-MOD

    International Nuclear Information System (INIS)

    Brotankova, J.; Adamek, J.; Stockel, J.; Martines, E.; Spolaore, M.; Cavazzana, R.; Serianni, G.; Vianello, N.; Zuin, M.

    2009-01-01

    The ball-pen probe (BPP) is an innovative electric probe for direct measurements of the plasma potential. This probe was developed in IPP Prague and it is based on the Katsumata probe concept. Combined measurements of the plasma potential by a BPP and floating potential by a Langmuir probe provide also the value of the electron temperature. First test of the BPP on the RFX-mod reversed field pinch in Padova has been performed in November 2006. The BPP head, made of boron nitride, is equipped with four graphite collectors, which are positioned at four different radial positions h inside four shafts hollow into the probe head. The radial profile of the plasma potential and also the electron temperature were measured

  18. MOSS spectroscopic camera for imaging time resolved plasma species temperature and flow speed

    Energy Technology Data Exchange (ETDEWEB)

    Michael, Clive; Howard, John [Australian National Univ., Plasma Research Laboratory, Canberra (Australia)

    2000-03-01

    A MOSS (Modulated Optical Solid-State) spectroscopic camera has been devised to monitor the spatial and temporal variations of temperatures and flow speeds of plasma ion species, the Doppler broadening measurement being made of spectroscopic lines specified. As opposed to a single channel MOSS spectrometer, the camera images light from plasma onto an array of light detectors, being mentioned 2D imaging of plasma ion temperatures and flow speeds. In addition, compared to a conventional grating spectrometer, the MOSS camera shows an excellent light collecting performance which leads to the improvement of signal to noise ratio and of time resolution. The present paper first describes basic items of MOSS spectroscopy, then follows MOSS camera with an emphasis on the optical system of 2D imaging. (author)

  19. Surface characterization of polyethylene terephthalate films treated by ammonia low-temperature plasma

    International Nuclear Information System (INIS)

    Zheng Zhiwen; Ren Li; Feng Wenjiang; Zhai Zhichen; Wang Yingjun

    2012-01-01

    In order to study the surface characterization and protein adhesion behavior of polyethylene terephthalate film, low temperature ammonia plasma was used to modify the film. Effects of plasma conditions of the surface structures and properties were investigated. Results indicated that surface hydrophilicity of polyethylene terephthalate was significantly improved by ammonia plasma treatment. Ammonia plasma played the role more important than air treatment in the process of modification. Furthermore, by Fourier Transform Infrared spectra some new bonds such as -N=O and N-H which could result in the improvement of the surface hydrophilicity were successfully grafted on the film surface. Atom force microscope experiments indicated that more protein adsorbed on hydrophobic surfaces than hydrophilic ones, and the blobs arranged in a straight line at etching surface by plasma. Modified membrane after ammonia plasma treatment had a good cell affinity and could be effective in promoting the adhesion and growth of cells on the material surface. Timeliness experiments showed that the plasma treatment gave the material a certain performance only in a short period of time and the hydrophobicity recovered after 12 days.

  20. Temperature and Nitric Oxide Generation in a Pulsed Arc Discharge Plasma

    International Nuclear Information System (INIS)

    Namihira, T.; Sakai, S.; Matsuda, M.; Wang, D.; Kiyan, T.; Akiyama, H.; Okamoto, K.; Toda, K.

    2007-01-01

    Nitric oxide (NO) is increasingly being used in medical treatments of high blood pressure, acute respiratory distress syndrome and other illnesses related to the lungs. Currently a NO inhalation system consists of a gas cylinder of N 2 mixed with a high concentration of NO. This arrangement is potentially risky due to the possibility of an accidental leak of NO from the cylinder. The presence of NO in the air leads to the formation of nitric dioxide (NO 2 ), which is toxic to the lungs. Therefore, an on-site generator of NO would be highly desirable for medical doctors to use with patients with lung disease. To develop the NO inhalation system without a gas cylinder, which would include a high concentration of NO, NAMIHIRA et al have recently reported on the production of NO from room air using a pulsed arc discharge. In the present work, the temperature of the pulsed arc discharge plasma used to generate NO was measured to optimize the discharge condition. The results of the temperature measurements showed the temperature of the pulsed arc discharge plasma reached about 10,000 K immediately after discharge initiation and gradually decreased over tens of microseconds. In addition, it was found that NO was formed in a discharge plasma having temperatures higher than 9,000 K and a smaller input energy into the discharge plasma generates NO more efficiently than a larger one

  1. Two-temperature transport coefficients of SF6–N2 plasma

    International Nuclear Information System (INIS)

    Yang, Fei; Chen, Zhexin; Wu, Yi; Rong, Mingzhe; Wang, Chunlin; Guo, Anxiang; Liu, Zirui

    2015-01-01

    Sulfur hexafluoride (SF 6 ) is widely adopted in electric power industry, especially in high-voltage circuit breakers and gas-insulated switchgear. However, the use of SF 6 is limited by its high liquidation temperature and high global warming potential. Recently, research shows SF 6 –N 2 mixture, which shows environmental friendliness and good electrical properties, may be a feasible substitute for pure SF 6 . This paper is devoted to the calculation of and transport coefficients of SF 6 –N 2 mixture under both LTE (local thermodynamic equilibrium) and non-LTE condition. The two–temperature mass action law was used to determine the composition. The transport coefficients were calculated by classical Chapman–Enskog method simplified by Devoto. The thermophysical properties are presented for electron temperatures of 300–40 000 K, ratios of electron to heavy species temperature of 1–10 and N 2 mole fraction of 0%–100% at atmospheric pressure. The ionization processes under both LTE and non-LTE have been discussed. The results show that deviations from local thermodynamic equilibrium significantly affect the properties of SF 6 –N 2 plasma, especially before the plasma is fully ionized. The different influence of N 2 on properties for SF 6 –N 2 plasma in and out of LTE has been found. The results will serve as reliable reference data for computational simulation of the behavior of SF 6 –N 2 plasmas

  2. Megawatt low-temperature DC plasma generator with divergent channels of gas-discharge tract

    Science.gov (United States)

    Gadzhiev, M. Kh.; Isakaev, E. Kh.; Tyuftyaev, A. S.; Yusupov, D. I.; Sargsyan, M. A.

    2017-04-01

    We have developed and studied a new effective megawatt double-unit generator of low-temperature argon plasma, which belongs to the class of dc plasmatrons and comprises the cathode and anode units with divergent gas-discharge channels. The generator has an efficiency of about 80-85% and ensures a long working life at operating currents up to 4000 A.

  3. Transition to Collisionless Ion-Temperature-Gradient-Driven Plasma Turbulence: A Dynamical Systems Approach

    International Nuclear Information System (INIS)

    Kolesnikov, R.A.; Krommes, J.A.

    2005-01-01

    The transition to collisionless ion-temperature-gradient-driven plasma turbulence is considered by applying dynamical systems theory to a model with 10 degrees of freedom. The study of a four-dimensional center manifold predicts a 'Dimits shift' of the threshold for turbulence due to the excitation of zonal flows and establishes (for the model) the exact value of that shift

  4. Guidelines for etching silicon MEMS structures using fluorine high-density plasmas at cryogenic temperatures

    NARCIS (Netherlands)

    de Boer, Meint J.; Gardeniers, Johannes G.E.; Jansen, Henricus V.; Gilde, M.J.; Roelofs, Gerard; Sasserath, Jay N.; Elwenspoek, Michael Curt

    This paper presents guidelines for the deep reactive ion etching (DRIE) of silicon MEMS structures, employing SF6/O2-based high-density plasmas at cryogenic temperatures. Procedures of how to tune the equipment for optimal results with respect to etch rate and profile control are described. Profile

  5. Ion temperature gradient driven mode in presence of transverse velocity shear in magnetized plasmas

    DEFF Research Database (Denmark)

    Chakrabarti, N.; Juul Rasmussen, J.; Michelsen, Poul

    2005-01-01

    The effect of sheared poloidal flow on the toroidal branch of the ion temperature gradient driven mode of magnetized nonuniform plasma is studied. A novel "nonmodal" calculation is used to analyze the problem. It is shown that the transverse shear flow considerably reduced the growth...

  6. Ionization equilibrium and radiation losses of molybdenum in a high temperature plasma

    International Nuclear Information System (INIS)

    1976-11-01

    The ionization equilibrium and the associated radiation losses of molybdenum have been calculated as a function of the electron temperature. In the 1-2keV range the computed fractional abundances are supported by experimental facts obtained in T.F.R. Tokamak plasmas

  7. Nonlocal effects in a bounded low-temperature plasma with fast electrons

    International Nuclear Information System (INIS)

    DeJoseph, C. A. Jr.; Demidov, V. I.; Kudryavtsev, A. A.

    2007-01-01

    Effects associated with nonlocality of the electron energy distribution function (EEDF) in a bounded, low-temperature plasma containing fast electrons, can lead to a significant increase in the near-wall potential drop, leading to self-trapping of fast electrons in the plasma volume, even if the density of this group is only a small fraction (∼0.001%) of the total electron density. If self-trapping occurs, the fast electrons can substantially increase the rate of stepwise excitation, supply additional heating to slow electrons, and reduce their rate of diffusion cooling. Altering the source terms of these fast electrons will, therefore, alter the near-wall sheath and, through modification of the EEDF, a number of plasma parameters. Self-trapping of fast electrons is important in a variety of plasmas, including hollow-cathode discharges and capacitive rf discharges, and is especially pronounced in an afterglow plasma, which is a key phase of any pulse-modulated discharge. In the afterglow, the electron temperature is less than a few tenths of an electron volt, and the fast electrons will have energies typically greater than an electron volt. It is shown that in the afterglow plasma of noble gases, fast electrons, arising from Penning ionization of metastable atoms, can lead to the above condition and significantly change the plasma and sheath properties. Similar effects can be important in technologically relevant electronegative gas plasmas, where fast electrons can arise due to electron detachment in collisions of negative ions with atomic species. Both experimental and modeling results are presented to illustrate these effects

  8. Physics and engineering of singlet delta oxygen production in low-temperature plasma

    International Nuclear Information System (INIS)

    Ionin, A A; Kochetov, I V; Napartovich, A P; Yuryshev, N N

    2007-01-01

    An overview is presented of experimental and theoretical research in the field of physics and engineering of singlet delta oxygen (SDO) production in low-temperature plasma of various electric discharges. Attention is paid mainly to the SDO production with SDO yield adequate for the development of an electric discharge oxygen-iodine laser (DOIL). The review comprises a historical sketch describing the main experimental results on SDO physics in low-temperature plasma obtained since the first detection of SDO in electric discharge in the 1950s and the first attempt to launch a DOIL in the 1970s up to the mid-1980s when several research groups started their activity aimed at DOIL development, stimulated by success in the development of a chemical oxygen-iodine laser (COIL). A detailed analysis of theoretical and experimental research on SDO production in electric discharge from the mid-1980s to the present, when the first DOIL has been launched, is given. Different kinetic models of oxygen low-temperature plasma are compared with the model developed by the authors. The latter comprises electron kinetics based on the accompanying solution of the electron Boltzmann equation, plasma chemistry including reactions of excited molecules and numerous ion-molecular reactions, thermal energy balance and electric circuit equation. The experimental part of the overview is focused on the experimental methods of SDO detection including experiments on the measurements of the Einstein coefficient for SDO transition a 1 Δ g - X 3 Σ g - and experimental procedures of SDO production in self-sustained and non-self-sustained discharges and analysis of different plasma-chemical processes occurring in oxygen low-temperature plasma which brings limitation to the maximum SDO yield and to the lifetime of the SDO in an electric discharge and its afterglow. Quite recently obtained results on gain and output characteristics of DOIL and some projects aimed at the development of high-power DOIL

  9. Temperature and Electron Density Determination on Laser-Induced Breakdown Spectroscopy (LIBS) Plasmas: A Physical Chemistry Experiment

    Science.gov (United States)

    Najarian, Maya L.; Chinni, Rosemarie C.

    2013-01-01

    This laboratory is designed for physical chemistry students to gain experience using laser-induced breakdown spectroscopy (LIBS) in understanding plasma diagnostics. LIBS uses a high-powered laser that is focused on the sample causing a plasma to form. The emission of this plasma is then spectrally resolved and detected. Temperature and electron…

  10. Measurement of excitation, ionization, and electron temperatures and positive ion concentrations in a 144 MHz inductively coupled radiofrequency plasma

    International Nuclear Information System (INIS)

    Walters, P.E.; Chester, T.L.; Winefordner, J.D.

    1977-01-01

    Diagnostic measurements of 144 MHz radiofrequency inductively coupled plasmas at pressures between 0.5 and 14 Torr have been made. Other variables studied included the gas type (Ar or Ne) and material in plasma (Ti or Tl). Parameters measured included excitation temperatures via the atomic Boltzmann plot and the two-line method, ionization electric probes. Excitation temperatures increased as the pressure of Ar or Ne plasmas decreased and reached a maximum of approx.9000 degreeK in the latter case and approx.6700 degreeK in the former case; Tl in the Ar plasma resulted in in a smaller rate of decrease of excitation temperature with increase of pressure of Ar. The ionization temperatures were lower than the excitation temperatures and were similar for both the Ar and Ne plasmas. Electron temperatures were about 10 times higher than the excitation temperatures indicating non-LTE behavior. Again, the electron temperatures indicating in Ne were considerably higher than in Ar. With the presence of metals, the electron temperatures with a metal in the Ar plasma were higher than in the absence. Positive ion concentrations were also measured for the various plasmas and were found to be similar (approx.10 18 m -3 ) in both the Ar and Ne plasmas. The presence of metals caused significant increase in the positive ion concentrations. From the results obtained, the optimum Ar pressure for Tl electrodeless discharge lamps operated at 144 MHz would be between 2 and 4 Torr

  11. Energization of the Ring Current through Convection of Substorm Enhancements of the Plasma Sheet Source.

    Science.gov (United States)

    Menz, A.; Kistler, L. M.; Mouikis, C.; Spence, H. E.; Henderson, M. G.; Matsui, H.

    2017-12-01

    It has been shown that electric field strength and night-side plasma sheet density are the two best predictors of the adiabatic energy gain of the ring current during geomagnetic storms (Liemohn and Khazanov, 2005). While H+ dominates the ring current during quiet times, O+ can contribute substantially during geomagnetic storms. Substorm activity provides a mechanism to enhance the energy density of O+ in the plasma sheet during geomagnetic storms, which is then convected adiabatically into the inner-magnetosphere. Using the Van Allen Probes data in the the plasma sheet source region (defined as L>5.5 during storms) and the inner magnetosphere, along with LANL-GEO data to identify substorm injection times, we show that adiabatic convection of O+ enhancements in the source region can explain the observed enhancements in the inner magnetosphere. We use the UNH-IMEF electric field model to calculate drift times from the source region to the inner magnetosphere to test whether enhancements in the inner-magnetosphere can be explained by dipolarization driven enhancements in the plasma sheet source hours before.

  12. Analyses of experimental observations of electron temperatures in the near wake of a model in a laboratory-simulated solar wind plasma

    International Nuclear Information System (INIS)

    Intriligator, D.S.; Steele, G.R.

    1985-01-01

    Laboratory experiments have been performed that show the effect on the electron temperature of inserting a spherical conducting model, larger than the Debye length, into a free-streaming high-energy (1 kv) unmagnetized hydrogen plasma. These experiments are the first electron temperature experiments conducted at energies and compositions directly relevant to solar wind and astrophysical plasma phenomena. The incident plasma parameters were held constant. A large number of axial profiles of the electron temperature ratios T/sub e//sub in// T/sub e//sub out/ behind the model downstream in the model wake are presented. A rigorous statistical approach is used in the analysis of the electron temperature ratio data in both our experimental laboratory data and in our reanalysis of the published data of others. The following new results ae obtained: (1) In energetic plasma flow there is no overall temperature enhancement in the near wake since the best fit to the T/sub e//sub i/n/ T/sub e//sub out/ data is a horizontal straight line having a mean value of 1.05; (2) No statistically significant electron temperature enhancement peaks or depressions exist in the near-wake region behind a model at zero potential in a high-energy plasma even at distances less than or equal to Ma, where M is the acoustic Mach number and a is the model radius. This implies a ''filling in'' of electrons in the wake region which may be due to the higher mobility of these energetic electrons. This mechanism may permit the solar wind electrons to significantly contribute to the maintenance of the nightside ionosphere at Venus

  13. Apparatus and method for enhanced chemical processing in high pressure and atmospheric plasmas produced by high frequency electromagnetic waves

    Science.gov (United States)

    Efthimion, Philip C.; Helfritch, Dennis J.

    1989-11-28

    An apparatus and method for creating high temperature plasmas for enhanced chemical processing of gaseous fluids, toxic chemicals, and the like, at a wide range of pressures, especially at atmospheric and high pressures includes an electro-magnetic resonator cavity, preferably a reentrant cavity, and a wave guiding structure which connects an electro-magnetic source to the cavity. The cavity includes an intake port and an exhaust port, each having apertures in the conductive walls of the cavity sufficient for the intake of the gaseous fluids and for the discharge of the processed gaseous fluids. The apertures are sufficiently small to prevent the leakage of the electro-magnetic radiation from the cavity. Gaseous fluid flowing from the direction of the electro-magnetic source through the guiding wave structure and into the cavity acts on the plasma to push it away from the guiding wave structure and the electro-magnetic source. The gaseous fluid flow confines the high temperature plasma inside the cavity and allows complete chemical processing of the gaseous fluids at a wide range of pressures.

  14. Characterisation of silicon carbide films deposited by plasma-enhanced chemical vapour deposition

    International Nuclear Information System (INIS)

    Iliescu, Ciprian; Chen Bangtao; Wei Jiashen; Pang, A.J.

    2008-01-01

    The paper presents a characterisation of amorphous silicon carbide films deposited in plasma-enhanced chemical vapour deposition (PECVD) reactors for MEMS applications. The main parameter was optimised in order to achieve a low stress and high deposition rate. We noticed that the high frequency mode (13.56 MHz) gives a low stress value which can be tuned from tensile to compressive by selecting the correct power. The low frequency mode (380 kHz) generates high compressive stress (around 500 MPa) due to ion bombardment and, as a result, densification of the layer achieved. Temperature can decrease the compressive value of the stress (due to annealing effect). A low etching rate of the amorphous silicon carbide layer was noticed for wet etching in KOH 30% at 80 o C (around 13 A/min) while in HF 49% the layer is practically inert. A very slow etching rate of amorphous silicon carbide layer in XeF 2 -7 A/min- was observed. The paper presents an example of this application: PECVD-amorphous silicon carbide cantilevers fabricated using surface micromachining by dry-released technique in XeF 2

  15. Atmospheric pressure plasma enhanced chemical vapor deposition of zinc oxide and aluminum zinc oxide

    International Nuclear Information System (INIS)

    Johnson, Kyle W.; Guruvenket, Srinivasan; Sailer, Robert A.; Ahrenkiel, S. Phillip; Schulz, Douglas L.

    2013-01-01

    Zinc oxide (ZnO) and aluminum-doped zinc oxide (AZO) thin films were deposited via atmospheric pressure plasma enhanced chemical vapor deposition. A second-generation precursor, bis(1,1,1,5,5,5-hexafluoro-2,4-pentanedionato)(N,N′-diethylethylenediamine) zinc, exhibited significant vapor pressure and good stability at one atmosphere where a vaporization temperature of 110 °C gave flux ∼ 7 μmol/min. Auger electron spectroscopy confirmed that addition of H 2 O to the carrier gas stream mitigated F contamination giving nearly 1:1 metal:oxide stoichiometries for both ZnO and AZO with little precursor-derived C contamination. ZnO and AZO thin film resistivities ranged from 14 to 28 Ω·cm for the former and 1.1 to 2.7 Ω·cm for the latter. - Highlights: • A second generation precursor was utilized for atmospheric pressure film growth. • Addition of water vapor to the carrier gas stream led to a marked reduction of ZnF 2 . • Carbonaceous contamination from the precursor was minimal

  16. The Effect of Temperature on the Spectral Emission of Plasma Induced in Water

    Directory of Open Access Journals (Sweden)

    B. Charfi

    2013-01-01

    Full Text Available A numerical modeling investigation of the spectral emission of laser-induced plasma in MgCl2-NaCl aqueous solution has been presented. A model based on equilibrium equations has been developed for the computation of the plasma composition and excited levels population. Physical interpretation is presented to comment on firstly the evolution of atomic species number densities, and secondly on the population of the excited species emitting MgII and NaI resonant lines for temperatures ranging from 3000 K to 20 000 K. It is shown that MgII line reach a maximum of population on the issuing level, at norm temperature of 13800 K. Whereas, NaI line presents two norm temperatures, evaluated at 3300 K and 11700 K. This splitting of the NaI norm temperature is explained by the low-ionization potential and weak concentration of the sodium atom in this aqueous solution. Thus, the proposed model can be useful to predict the optimal plasma temperature for the detection of given chemical element, which is not easy to reveal experimentally.

  17. Characterization of low-temperature microwave loss of thin aluminum oxide formed by plasma oxidation

    Energy Technology Data Exchange (ETDEWEB)

    Deng, Chunqing, E-mail: cdeng@uwaterloo.ca; Otto, M.; Lupascu, A., E-mail: alupascu@uwaterloo.ca [Institute for Quantum Computing, Department of Physics and Astronomy, and Waterloo Institute for Nanotechnology, University of Waterloo, Waterloo, Ontario N2L 3G1 (Canada)

    2014-01-27

    We report on the characterization of microwave loss of thin aluminum oxide films at low temperatures using superconducting lumped resonators. The oxide films are fabricated using plasma oxidation of aluminum and have a thickness of 5 nm. We measure the dielectric loss versus microwave power for resonators with frequencies in the GHz range at temperatures from 54 to 303 mK. The power and temperature dependence of the loss are consistent with the tunneling two-level system theory. These results are relevant to understanding decoherence in superconducting quantum devices. The obtained oxide films are thin and robust, making them suitable for capacitors in compact microwave resonators.

  18. Simulation of a coupled dynamic system of temperature and density in a fusion plasma

    International Nuclear Information System (INIS)

    Le Roux, M.N.; Weiland, J.; Wilhelmsson, H.

    1992-01-01

    Simulation studies of a coupled system of equations for the evolution of temperature and density have been performed. The results are presented in graphs displaying the evolution in time of the temperature and density profiles, as well as in phase-plane plots, relating the central values of temperature and density. Particular emphasis is devoted to the particle and heat pinch effects, which tend to counter-balance the ordinary diffusion, and to co-operate with the alpha particle heating in sustaining plasma equilibrium. Oscillatory approaches to equilibria are recorded. 28 refs., 20 figs

  19. Self-organized profile relaxation by ion temperature gradient instability in toroidal plasmas

    International Nuclear Information System (INIS)

    Kishimoto, Y.; Tajima, T.; LeBrun, M.J.; Gray, M.G.; Kim, J.Y.; Horton, W.

    1993-02-01

    Toroidal effects on the ion-temperature gradient mode are found to dictate the temperature evolution and the subsequent relaxed profile realization according to our toroidal particle simulation. Both in the strongly unstable fluid regime as well as in the near-marginal kinetic regime we observe that the plasma maintains an exponential temperature profile and forces the heat flux to be radially independent. The self-organized critical relaxed state is sustained slightly above the marginal stability, where the weak wave growth balances the wave decorrelation

  20. Temperature dependence of mode conversion in warm, unmagnetized plasmas with a linear density profile

    Energy Technology Data Exchange (ETDEWEB)

    Yu, Dae Jung; Lee, Dong-Hun [School of Space Research, Kyung Hee University, Yongin (Korea, Republic of); Kim, Kihong [Division of Energy Systems Research, Ajou University, Suwon (Korea, Republic of)

    2013-06-15

    We study theoretically the linear mode conversion between electromagnetic waves and Langmuir waves in warm, stratified, and unmagnetized plasmas, using a numerically precise calculation based on the invariant imbedding method. We verify that the principle of reciprocity for the forward and backward mode conversion coefficients holds precisely regardless of temperature. We also find that the temperature dependence of the mode conversion coefficient is substantially stronger than that previously reported. Depending on the wave frequency and the incident angle, the mode conversion coefficient is found to increase or decrease with the increase of temperature.

  1. Temperature anisotropy in a cyclotron resonance heated tokamak plasma and the generation of poloidal electric field

    International Nuclear Information System (INIS)

    Choe, W.; Ono, M.; Chang, C.S.

    1994-11-01

    The temperature anisotropy generated by cyclotron resonance heating of tokamak plasmas is calculated and the poloidal equilibrium electric field due to the anisotropy is studied. For the calculation of anisotropic temperatures, bounce-averaged Fokker-Planck equation with a bi-Maxwellian distribution function of heated particles is solved, assuming a moderate wave power and a constant quasilinear cyclotron resonance diffusion coefficient. The poloidal electrostatic potential variation is found to be proportional to the particle density and the degree of temperature anisotropy of warm species created by cyclotron resonance heating

  2. Noise temperature improvement for magnetic fusion plasma millimeter wave imaging systems.

    Science.gov (United States)

    Lai, J; Domier, C W; Luhmann, N C

    2014-03-01

    Significant progress has been made in the imaging and visualization of magnetohydrodynamic and microturbulence phenomena in magnetic fusion plasmas [B. Tobias et al., Plasma Fusion Res. 6, 2106042 (2011)]. Of particular importance have been microwave electron cyclotron emission imaging and microwave imaging reflectometry systems for imaging T(e) and n(e) fluctuations. These instruments have employed heterodyne receiver arrays with Schottky diode mixer elements directly connected to individual antennas. Consequently, the noise temperature has been strongly determined by the conversion loss with typical noise temperatures of ~60,000 K. However, this can be significantly improved by making use of recent advances in Monolithic Microwave Integrated Circuit chip low noise amplifiers to insert a pre-amplifier in front of the Schottky diode mixer element. In a proof-of-principle design at V-Band (50-75 GHz), significant improvement of noise temperature from the current 60,000 K to measured 4000 K has been obtained.

  3. Noise temperature improvement for magnetic fusion plasma millimeter wave imaging systems

    International Nuclear Information System (INIS)

    Lai, J.; Domier, C. W.; Luhmann, N. C.

    2014-01-01

    Significant progress has been made in the imaging and visualization of magnetohydrodynamic and microturbulence phenomena in magnetic fusion plasmas [B. Tobias et al., Plasma Fusion Res. 6, 2106042 (2011)]. Of particular importance have been microwave electron cyclotron emission imaging and microwave imaging reflectometry systems for imaging T e and n e fluctuations. These instruments have employed heterodyne receiver arrays with Schottky diode mixer elements directly connected to individual antennas. Consequently, the noise temperature has been strongly determined by the conversion loss with typical noise temperatures of ∼60 000 K. However, this can be significantly improved by making use of recent advances in Monolithic Microwave Integrated Circuit chip low noise amplifiers to insert a pre-amplifier in front of the Schottky diode mixer element. In a proof-of-principle design at V-Band (50–75 GHz), significant improvement of noise temperature from the current 60 000 K to measured 4000 K has been obtained

  4. Dusty plasma in a glow discharge in helium in temperature range of 5–300 K

    Energy Technology Data Exchange (ETDEWEB)

    Samoilov, I. S.; Baev, V. P.; Timofeev, A. V., E-mail: timofeevalvl@gmail.com; Amirov, R. Kh.; Kirillin, A. V.; Nikolaev, V. S.; Bedran, Z. V. [Russian Academy of Sciences, Joint Institute for High Temperatures (Russian Federation)

    2017-03-15

    Dusty plasma structures in glow discharge in helium in the temperature range of 5–300 K are investigated experimentally. We have described the experimental setup that makes it possible to continuously vary the temperature regime. The method for experimental data processing has been described. We have measured interparticle distances in the temperature range of 9–295 K and compared them with the Debye radius. We indicate the ranges of variations in experimental parameters in which plasma–dust structures are formed and various types of their behavior are manifested (rotation, vibrations of structures, formation of vertical linear chains, etc.). The applicability of the Yukawa potential to the description of the structural properties of a dusty plasma in the experimental conditions is discussed.

  5. Recombination in deuterium plasma at cryogenic temperatures (down to 130 K)

    Energy Technology Data Exchange (ETDEWEB)

    Novotny, O.; Glosik, J.; Pysanenko, A.; Zakouril, P.; Plasil, R.; Tichy, M. [Prague Charles Univ., Faculty of Mathematics and Physics (Czech Republic)

    2004-07-01

    The ions H{sub 3}{sup +} and D{sub 3}{sup +} play an important role in the kinetics of media of astrophysical interest but also in laboratory produced plasmas (discharges, fusion plasmas). In the presented study variable temperature flowing afterglow with Langmuir probe (VT-FALP) was used to study plasma decay in D{sub 2}/He mixture at temperatures down to 130 K and total pressure up to 10 Torr. Large extend of partial number densities of D{sub 2} (10{sup 12} - 3 x 10{sup 15} cm{sup -3}) were used in the experiments. Langmuir probes and mass spectrometers were applied to monitor decay of the plasma during the afterglow. The study is a continuation of our previous measurements of recombination rate coefficients of D{sub 3}{sup +} and D{sub 5}{sup +} ions. In these studies we observed dependence of the recombination rate coefficient on partial pressure of deuterium indicating that third-body assisted recombination is efficient and significantly contributes to recombination in decaying deuterium-containing plasma. (authors)

  6. New high temperature plasmas and sample introduction systems for analytical atomic emission and mass spectrometry

    International Nuclear Information System (INIS)

    Montaser, A.

    1993-01-01

    In this research, new high-temperature plasmas and new sample introduction systems are explored for rapid elemental and isotopic analysis of gases, solutions, and solids using mass spectrometry and atomic emission spectrometry. During the period January 1993--December 1993, emphasis was placed on (a) analytical investigations of atmospheric-pressure helium inductively coupled plasma (He ICP) that are suitable for atomization, excitation, and ionization of elements possessing high excitation and ionization energies; (b) simulation and computer modeling of plasma sources to predict their structure and fundamental and analytical properties without incurring the enormous cost of experimental studies; (c) spectrosopic imaging and diagnostic studies of high-temperature plasmas; (d) fundamental studies of He ICP discharges and argon-nitrogen plasma by high-resolution Fourier transform spectrometry; and (e) fundamental and analytical investigation of new, low-cost devices as sample introduction systems for atomic spectrometry and examination of new diagnostic techniques for probing aerosols. Only the most important achievements are included in this report to illustrate progress and obstacles. Detailed descriptions of the authors' investigations are outlined in the reprints and preprints that accompany this report. The technical progress expected next year is briefly described at the end of this report

  7. Uniformity and passivation research of Al2O3 film on silicon substrate prepared by plasma-enhanced atom layer deposition.

    Science.gov (United States)

    Jia, Endong; Zhou, Chunlan; Wang, Wenjing

    2015-01-01

    Plasma-enhanced atom layer deposition (PEALD) can deposit denser films than those prepared by thermal ALD. But the improvement on thickness uniformity and the decrease of defect density of the films deposited by PEALD need further research. A PEALD process from trimethyl-aluminum (TMA) and oxygen plasma was investigated to study the influence of the conditions with different plasma powers and deposition temperatures on uniformity and growth rate. The thickness and refractive index of films were measured by ellipsometry, and the passivation effect of alumina on n-type silicon before and after annealing was measured by microwave photoconductivity decay method. Also, the effects of deposition temperature and annealing temperature on effective minority carrier lifetime were investigated. Capacitance-voltage and conductance-voltage measurements were used to investigate the interface defect density of state (D it) of Al2O3/Si. Finally, Al diffusion P(+) emitter on n-type silicon was passivated by PEALD Al2O3 films. The conclusion is that the condition of lower substrate temperature accelerates the growth of films and that the condition of lower plasma power controls the films' uniformity. The annealing temperature is higher for samples prepared at lower substrate temperature in order to get the better surface passivation effects. Heavier doping concentration of Al increased passivation quality after annealing by the effective minority carrier lifetime up to 100 μs.

  8. Enhancing Electrochemical Performance of Graphene Fiber-Based Supercapacitors by Plasma Treatment.

    Science.gov (United States)

    Meng, Jie; Nie, Wenqi; Zhang, Kun; Xu, Fujun; Ding, Xin; Wang, Shiren; Qiu, Yiping

    2018-04-25

    Graphene fiber-based supercapacitors (GFSCs) hold high power density, fast charge-discharge rate, ultralong cycling life, exceptional mechanical/electrical properties, and safe operation conditions, making them very promising to power small wearable electronics. However, the electrochemical performance is still limited by the severe stacking of graphene sheets, hydrophobicity of graphene fibers, and complex preparation process. In this work, we develop a facile but robust strategy to easily enhance electrochemical properties of all-solid-state GFSCs by simple plasma treatment. We find that 1 min plasma treatment under an ambient condition results in 33.1% enhancement of areal specific capacitance (36.25 mF/cm 2 ) in comparison to the as-prepared GFSC. The energy density reaches 0.80 μW h/cm 2 in polyvinyl alcohol/H 2 SO 4 gel electrolyte and 18.12 μW h/cm 2 in poly(vinylidene difluoride)/ethyl-3-methylimidazolium tetrafluoroborate electrolyte, which are 22 times of that of as-prepared ones. The plasma-treated GFSCs also exhibit ultrahigh rate capability (69.13% for 40 s plasma-treated ones) and superior cycle stability (96.14% capacitance retention after 20 000 cycles for 1 min plasma-treated ones). This plasma strategy can be extended to mass-manufacture high-performance carbonaceous fiber-based supercapacitors, such as graphene and carbon nanotube-based ones.

  9. Adhesion enhancement of Al coatings on carbon/epoxy composite surfaces by atmospheric plasma

    International Nuclear Information System (INIS)

    Coulon, J.F.; Tournerie, N.; Maillard, H.

    2013-01-01

    Adhesion strengths between aluminium thin film coatings and manufactured carbon/epoxy composite surfaces were measured by assessing fracture tensile strengths using pull-off tests. The effect of the substrate roughness (nm to μm) of these composite surfaces on adhesion was studied by examining the surface free energies and adhesion strengths. The adhesion strengths of the coatings varied significantly. To improve the coating adhesion, each composite surface was treated with atmospheric plasma prior to deposition, which resulted in an increase in the surface free energy from approximately 40 mJ/m 2 to 70 mJ/m 2 because the plasma pretreatment led to the formation of hydrophilic C-O and C=O bonds on the composite surfaces, as demonstrated by X-ray photoelectron spectroscopy analyses. The adhesion strengths of the coatings were enhanced for all surface roughnesses studied. In our study, the effect of mechanical adhesion due to roughness was separated from the effect of modifying the chemical bonds with plasma activation. The adhesion ability of the pure resin was relatively weak. Increasing the surface roughness largely improved the adhesion of the resin surface. Plasma treatment of the pure resin also increased the surface adhesion. Our study shows that plasma activation effectively enhances the adhesion of manufactured composites, even when the surface roughness is on the order of microns. The ageing of the surface activation was also investigated, and the results demonstrate that atmospheric plasma has potential for use in the pretreatment of composite materials.

  10. Experimental investigation of lift enhancement for flying wing aircraft using nanosecond DBD plasma actuators

    Science.gov (United States)

    Yao, Junkai; Zhou, Danjie; He, Haibo; He, Chengjun; Shi, Zhiwei; Du, Hai

    2017-04-01

    The effects of the arrangement position and control parameters of nanosecond dielectric barrier discharge (NS-DBD) plasma actuators on lift enhancement for flying wing aircraft were investigated through wind tunnel experiments at a flow speed of 25 m s-1. The aerodynamic forces and moments were obtained by a six-component balance at angles of attack ranging from -4° to 28°. The lift, drag and pitching moment coefficients were compared for the cases with and without plasma control. The results revealed that the maximum control effect was achieved by placing the actuator at the leading edge of the inner and middle wing, for which the maximum lift coefficient increased by 37.8% and the stall angle of attack was postponed by 8° compared with the plasma-off case. The effects of modulation frequency and discharge voltage were also investigated. The results revealed that the lift enhancement effect of the NS-DBD plasma actuators was strongly influenced by the modulation frequency. Significant control effects were obtained at f = 70 Hz, corresponding to F + ≈ 1. The result for the pitching moment coefficient demonstrated that the plasma actuator can induce the reattachment of the separation flows when it is actuated. However, the results indicated that the discharge voltage had a negligible influence on the lift enhancement effect.

  11. Surface treatment of a titanium implant using low temperature atmospheric pressure plasmas

    Science.gov (United States)

    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.

  12. 13th TOPICAL CONFERENCE ON HIGH TEMPERATURE PLASMA DIAGNOSTICS SCIENTIFIC PROGRAM

    Energy Technology Data Exchange (ETDEWEB)

    C. BARNES

    2000-07-01

    Electron cyclotron emission (ECE) has been employed as a standard electron temperature profile diagnostic on many tokamaks and stellarators, but most magnetically confined plasma devices cannot take advantage of standard ECE diagnostics to measure temperature. They are either overdense, operating at high density relative to the magnetic field (e.g. {omega}{sub pe} >> {Omega}{sub ce} in a spherical torus) or they have insufficient density and temperature to reach the blackbody condition ({tau} > 2). Electron Bernstein waves (EBWs) are electrostatic waves which can propagate in overdense plasmas and have a high optical thickness at the electron cyclotron resonance layers, as a result of their large K{sub i}. This talk reports on measurements of EBW emission on the CDX-U spherical torus, where B{sub 0} {approx} 2 kG, {approx} 10{sup 13} cm{sup -3} and T{sub e} {approx} 10 - 200 eV. Results will be presented for both direct detection of EBWs and for mode-converted EBW emission. The EBW emission was absolutely calibrated and compared to the electron temperature profile measured by a multi-point Thomson scattering diagnostic. Depending on the plasma conditions, the mode-converted EBW radiation temperature was found to be {le} T{sub e} and the emission source was determined to be radially localized at the electron cyclotron resonance layer. A Langmuir triple probe was employed to measure changes in edge density profile in the vicinity of the upper hybrid resonance where the mode conversion of the EBWs is expected to occur. Changes in the mode conversion efficiency may explain the observation of mode-converted EBW radiation temperatures below T{sub e}. Initial results suggest EBW emission and EBW heating are viable concepts for plasmas where {omega}{sub pe} >> {Omega}{sub ce}.

  13. The influence of storage time and temperature on the measurement of serum, plasma and urine osmolality.

    Science.gov (United States)

    Bezuidenhout, Karla; Rensburg, Megan A; Hudson, Careen L; Essack, Younus; Davids, M Razeen

    2016-07-01

    Many clinical laboratories require that specimens for serum and urine osmolality determination be processed within 3 h of sampling or need to arrive at the laboratory on ice. This protocol is based on the World Health Organization report on sample storage and stability, but the recommendation lacks good supporting data. We studied the effect of storage temperature and time on osmolality measurements. Blood and urine samples were obtained from 16 patients and 25 healthy volunteers. Baseline serum, plasma and urine osmolality measurements were performed within 30 min. Measurements were then made at 3, 6, 12, 24 and 36 h on samples stored at 4-8℃ and room temperature. We compared baseline values with subsequent measurements and used difference plots to illustrate changes in osmolality. At 4-8℃, serum and plasma osmolality were stable for up to 36 h. At room temperature, serum and plasma osmolality were very stable for up to 12 h. At 24 and 36 h, changes from baseline osmolality were statistically significant and exceeded the total allowable error of 1.5% but not the reference change value of 4.1%. Urine osmolality was extremely stable at room temperature with a mean change of less than 1 mosmol/kg at 36 h. Serum and plasma samples can be stored at room temperature for up to 36 h before measuring osmolality. Cooling samples to 4-8℃ may be useful when delays in measurement beyond 12 h are anticipated. Urine osmolality is extremely stable for up to 36 h at room temperature. © The Author(s) 2015.

  14. Bremsstrahlung spectra for Al, Cs, and Au atoms in high-temperature, high-density plasmas

    International Nuclear Information System (INIS)

    Kim, L.; Pratt, R.H.; Tseng, H.K.

    1985-01-01

    Results are presented from a numerical calculation for the bremsstrahlung spectrum and Gaunt factors of Al, Cs, and Au atoms in high-temperature (-T), high-density (-rho) plasmas. Plasma temperatures kT = 0.1 and 1.0 keV and plasma densities rho = rho 0 (the normal solid density) and rho = 100rho 0 are considered. This allows us to determine the generality and identify the origins of features which we had previously identified in calculations for Cs. We also now present results for the total energy loss of an electron in such a plasma. We use a relativistic multipole code which treats the bremsstrahlung process as a single-electron transition in a static screened central potential. We take for the static potential corresponding to an atom in a hot dense plasma the finite-temperature, finite-density Thomas-Fermi model. This approach corresponds to an average atom in local thermodynamic equilibrium. In comparison to isolated-neutral-atom results we observe general suppression of cross sections and a particular suppression in the tip region of the spectrum. Within this model, both superscreening and shape resonances are found in the circumstances of extreme density. At more normal densities and except for the soft-photon end, the spectrum at these energies for an atom in a hot plasma (characterized by an average degree of ionization) can be well represented by the spectrum of the corresponding isolated ion, which has a similar potential shape at the distances which characterize the process

  15. Role of chlorine in the nanocrystalline silicon film formation by rf plasma-enhanced chemical vapor deposition of chlorinated materials

    International Nuclear Information System (INIS)

    Shirai, Hajime

    2004-01-01

    We demonstrate the disorder-induced low-temperature crystallization in the nanocrystalline silicon film growth by rf plasma-enhanced chemical vapor deposition of H 2 -diluted SiH 2 Cl 2 and SiCl 4 . The combination of the chemical reactivity of SiCld (d: dangling bond) and SiHCl complexes and the release of the disorder-induced stress near the growing surface tightly correlate with the phase transitionity of SiCld and SiHCl complexes near the growing surface with the aid of atomic hydrogen, which induce higher degree of disorder in the a-Si network. These features are most prominent in the SiCl 4 compared with those of SiH 2 Cl 2 and SiH 4 , which preferentially enhance the nanocrystalline Si formation

  16. Enhanced plasma wave detection of terahertz radiation using multiple high electron-mobility transistors connected in series

    KAUST Repository

    Elkhatib, Tamer A.; Kachorovskiǐ, Valentin Yu; Stillman, William J.; Veksler, Dmitry B.; Salama, Khaled N.; Zhang, Xicheng; Shur, Michael S.

    2010-01-01

    We report on enhanced room-temperature detection of terahertz radiation by several connected field-effect transistors. For this enhanced nonresonant detection, we have designed, fabricated, and tested plasmonic structures consisting of multiple InGaAs/GaAs pseudomorphic high electron-mobility transistors connected in series. Results show a 1.63-THz response that is directly proportional to the number of detecting transistors biased by a direct drain current at the same gate-to-source bias voltages. The responsivity in the saturation regime was found to be 170 V/W with the noise equivalent power in the range of 10-7 W/Hz0.5. The experimental data are in agreement with the detection mechanism based on the rectification of overdamped plasma waves excited by terahertz radiation in the transistor channel. © 2010 IEEE.

  17. Enhanced plasma wave detection of terahertz radiation using multiple high electron-mobility transistors connected in series

    KAUST Repository

    Elkhatib, Tamer A.

    2010-02-01

    We report on enhanced room-temperature detection of terahertz radiation by several connected field-effect transistors. For this enhanced nonresonant detection, we have designed, fabricated, and tested plasmonic structures consisting of multiple InGaAs/GaAs pseudomorphic high electron-mobility transistors connected in series. Results show a 1.63-THz response that is directly proportional to the number of detecting transistors biased by a direct drain current at the same gate-to-source bias voltages. The responsivity in the saturation regime was found to be 170 V/W with the noise equivalent power in the range of 10-7 W/Hz0.5. The experimental data are in agreement with the detection mechanism based on the rectification of overdamped plasma waves excited by terahertz radiation in the transistor channel. © 2010 IEEE.

  18. Spectral measurements of electron temperature in nonequilibrium highly ionized He plasma

    International Nuclear Information System (INIS)

    Korshunov, O V; Chinnov, V F; Kavyrshin, D I; Ageev, A G

    2016-01-01

    It has been experimentally shown that highly ionized He arc plasma does not achieve local thermodynamic equilibrium expected for plasmas with electron concentrations above 1 × 10 16 cm -3 like argon plasma. We have found that the reason for this deviation is strong nonisotropy of plasma. Triple electron recombination with temperatures of 2.5-3 eV is almost absent. Charged particles move from the arc ( r = 1 mm) to chamber walls due to ambipolar diffusion creating ionization nonequilibrium over the excited states rendering Boltzmann distribution and Saha equation inapplicable for determining electron temperature. A method for determining electron temperature is suggested that is based on using the relative intensities of the atomic and ion lines. Its advantage lies in an energy gap between these lines’ states over 50 eV that reduces the influence of nonequilibrium on the result. This influence can be taken into account if the ionization energies of emitting states of atom and ion have close values. The suggested method can be expanded for any media including those with dimensional nonisotropy that have both atomic and ion lines in their emission spectra. (paper)

  19. X-ray Heating and Electron Temperature of Laboratory Photoionized Plasmas

    Science.gov (United States)

    Mancini, Roberto; Lockard, Tom; Mayes, Daniel C.; Loisel, Guillaume; Bailey, James E.; Rochau, Gregory; Abdallah, J.; Golovkin, I.

    2018-06-01

    In separate experiments performed at the Z facility of Sandia National Laboratories two different samples were employed to produce and characterize photoionized plasmas. One was a gas cell filled with neon, and the other was a thin silicon layer coated with plastic. Both samples were driven by the broadband x-ray flux produced at the collapse of a wire array z-pinch implosion. Transmission spectroscopy of a narrowband portion of the x-ray flux was used to diagnose the charge state distribution, and the electron temperature was extracted from a Li-like ion level population ratio. To interpret the temperature measurement, we performed Boltzmann kinetics and radiation-hydrodynamic simulations. We found that non-equilibrium atomic physics and the coupling of the radiation flux to the atomic level population kinetics play a critical role in modeling the x-ray heating of photoionized plasmas. In spite of being driven by similar x-ray drives, differences of ionization and charged state distributions in the neon and silicon plasmas are reflected in the plasma heating and observed electron temperatures.This work was sponsored in part by DOE Office of Science Grant DE-SC0014451, and the Z Facility Fundamental Science Program of SNL.

  20. Surface temperature: A key parameter to control the propanethiol plasma polymer chemistry

    Energy Technology Data Exchange (ETDEWEB)

    Thiry, Damien, E-mail: damien.thiry@umons.ac.be; Aparicio, Francisco J. [Chimie des Interactions Plasma Surface (ChIPS), CIRMAP, Université de Mons, 23 Place du Parc, B-7000 Mons (Belgium); Laha, Priya; Terryn, Herman [Research Group Electrochemical and Surface Engineering (SURF), Department of Materials and Chemistry (MACH), Pleinlaan 2, 1050 Brussel (Belgium); Snyders, Rony [Chimie des Interactions Plasma Surface (ChIPS), CIRMAP, Université de Mons, 23 Place du Parc, B-7000 Mons, Belgium and Materia Nova Research Center, Parc Initialis, B-7000 Mons (Belgium)

    2014-09-01

    In this work, the influence of the substrate temperature (T{sub s}) on the chemical composition of propanethiol plasma polymers was investigated for a given set of plasma conditions. In a first study, a decrease in the atomic sulfur content (at. %S) with the deposition time (t{sub d}) was observed. This behavior is explained by the heating of the growing film during deposition process, limiting the incorporation of stable sulfur-based molecules produced in the plasma. Experiments carried out by controlling the substrate temperature support this hypothesis. On the other hand, an empirical law relating the T{sub s} and the at. %S was established. This allows for the formation of gradient layer presenting a heterogeneous chemical composition along the thickness, as determined by depth profile analysis combining X-ray photoelectron spectroscopy and C{sub 60} ion gun sputtering. The experimental data fit with the one predicted from our empiric description. The whole set of our results provide new insights in the relationship between the substrate temperature and the sulfur content in sulfur-based plasma polymers, essential for future developments.