Plasmas and intense laser light

International Nuclear Information System (INIS)

Kennedy, E.T.

1984-01-01

The present article begins with a description of the laser technology required to reach the high irradiances of interest and provides a brief outline of the more important diagnostic techniques used in investigating the plasmas. An introduction to plasma waves is given and the linear and nonlinear excitation of waves is discussed. The remainder of the article describes some of the experimental evidence supporting the interpretation of the plasma behaviour at high laser-light intensities in terms of the excitation of plasma waves and the subsequent heating of plasma by these waves. (author)

Radiation induced changes in plasma total protein nitrogen and urinary total nitrogen in desert rodent and albino rats subjected to dietary protein deficiency

International Nuclear Information System (INIS)

Roushdy, H.; El-Husseini, M.; Saleh, F.

1986-01-01

The effect of gamma-irradiation on plasma total protein nitrogen and urinary total nitrogen was studied in the desert rodent, psammomy obesus obesus and albino rats subjected to dietary protein deficiency. In albino rats kept on high protein diet, the radiation syndrome resulted in urine retention, while in those kept on non-protein diet, such phenomenon was recorded only with the high radiation level of 1170r. Radiation exposure to 780 and 1170r caused remarkable diuresis in psammomys obesus obesus whereas they induced significant urine retention in albino rats. The levels of plasma total protein nitrogen and urinary total nitrogen were higher in albino rats maintained on high protein diet than in those kept on non-protein diet. Radiation exposure caused an initial drop in plasma total protein nitrogen concentration, concomitant with an initial rise in total urinary nitrogen, radiation exposure of psammomys obesus obesus caused significant increase in the levels of plasma protein nitrogen and urinary total nitrogen. Psammomys obesus obesus seemed to be more affected by radiation exposure than did the albino rats

Control of work function of graphene by plasma assisted nitrogen doping

International Nuclear Information System (INIS)

Akada, Keishi; Terasawa, Tomo-o; Imamura, Gaku; Obata, Seiji; Saiki, Koichiro

2014-01-01

Nitrogen doping is expected to provide several intriguing properties to graphene. Nitrogen plasma treatment to defect-free and defective highly oriented pyrolytic graphite (HOPG) samples causes doping of nitrogen atom into the graphene layer. Nitrogen atoms are initially doped at a graphitic site (inside the graphene) for the defect-free HOPG, while doping to a pyridinic or a pyrrolic site (edge of the graphene) is dominant for the defective HOPG. The work function of graphene correlates strongly with the site and amount of doped nitrogen. Nitrogen atoms doped at a graphitic site lower the work function, while nitrogen atoms at a pyridinic or a pyrrolic site increase the work function. Control of plasma treatment time and the amount of initial defect could change the work function of graphite from 4.3 eV to 5.4 eV, which would open a way to tailor the nature of graphene for various industrial applications

Spectroscopic Investigation of Nitrogen Loaded ECR Plasmas

CERN Document Server

Ullmann, F; Zschornack, G; Küchler, D; Ovsyannikov, V P

1999-01-01

Energy dispersive X-ray spectroscopy on ions in the plasma and magnetic q/A-analysis of the extracted ions were used to determine the plasmaproperties of nitrogen loaded ECR plasmas.As the beam expands from a limited plasma region and the ion extraction process alters the plasma properties in the extraction meniscus thebeam composition does not correspond to the bulk plasma composition. The analysis of measured spectra of characteristic X-rays delivers a method to determine the ion charge state distribution and the electron energy distribution inside the plasma and does not alter the plasma anddoes not depend on the extraction and transmission properties of the ion extraction and transport system. Hence this method seems to be moreaccurate than the traditional magnetic analysis and allows to analyse different plasma regions.A comparison between ion charge state distributions determined from X-ray spectra and such from q/A-analysis shows significant differencesfor the mean ion charge states in the source plasm...

Thermal Plasma Spheroidization of High-Nitrogen Stainless Steel Powder Alloys Synthesized by Mechanical Alloying

Science.gov (United States)

Razumov, Nikolay G.; Popovich, Anatoly A.; Wang, QingSheng

2018-03-01

This paper presents the results of experimental studies on the treatment of Fe-23Cr-11Mn-1N high-nitrogen stainless steel powder alloys, synthesized by the mechanical alloying (MA) of elemental powders in the flow of a thermal plasma. Fe-23Cr-11Mn-1N high-nitrogen stainless steel powder alloys were prepared by MA in the attritor under an argon atmosphere. For spheroidization of Fe-23Cr-11Mn-1N high-nitrogen stainless steel powder alloys, the TekSphero 15 plant manufactured by Tekna Plasma Systems Inc was used. The studies have shown the possibility of obtaining Fe-23Cr-11Mn-1N high-nitrogen spherical powders steel alloys from the powder obtained by MA. According to the results of a series of experiments, it was found that the results of plasma spheroidization of powders essentially depend on the size of the fraction due to some difference in the particle shape and flowability, and on the gas regime of the plasma torch. It is established that during the plasma spheroidization process, some of the nitrogen leaves the alloy. The loss rate of nitrogen depends on the size of the initial particles.

Nitrogen plasma-treated multilayer graphene-based field effect transistor fabrication and electronic characteristics

Science.gov (United States)

Su, Wei-Jhih; Chang, Hsuan-Chen; Honda, Shin-ichi; Lin, Pao-Hung; Huang, Ying-Sheng; Lee, Kuei-Yi

2017-08-01

Chemical doping with hetero-atoms is an effective method used to change the characteristics of materials. Nitrogen doping technology plays a critical role in regulating the electronic properties of graphene. Nitrogen plasma treatment was used in this work to dope nitrogen atoms to modulate multilayer graphene electrical properties. The measured I-V multilayer graphene-base field-effect transistor characteristics (GFETs) showed a V-shaped transfer curve with the hole and electron region separated from the measured current-voltage (I-V) minimum. GFETs fabricated with multilayer graphene from chemical vapor deposition (CVD) exhibited p-type behavior because of oxygen adsorption. After using different nitrogen plasma treatment times, the minimum in I-V characteristic shifted into the negative gate voltage region with increased nitrogen concentration and the GFET channel became an n-type semiconductor. GFETs could be easily fabricated using this method with potential for various applications. The GFET transfer characteristics could be tuned precisely by adjusting the nitrogen plasma treatment time.

Effect of feed-gas humidity on nitrogen atmospheric-pressure plasma jet for biological applications.

Science.gov (United States)

Stephan, Karl D; McLean, Robert J C; DeLeon, Gian; Melnikov, Vadim

2016-11-14

We investigate the effect of feed-gas humidity on the oxidative properties of an atmospheric-pressure plasma jet using nitrogen gas. Plasma jets operating at atmospheric pressure are finding uses in medical and biological settings for sterilization and other applications involving oxidative stress applied to organisms. Most jets use noble gases, but some researchers use less expensive nitrogen gas. The feed-gas water content (humidity) has been found to influence the performance of noble-gas plasma jets, but has not yet been systematically investigated for jets using nitrogen gas. Low-humidity and high-humidity feed gases were used in a nitrogen plasma jet, and the oxidation effect of the jet was measured quantitatively using a chemical dosimeter known as FBX (ferrous sulfate-benzoic acid-xylenol orange). The plasma jet using high humidity was found to have about ten times the oxidation effect of the low-humidity jet, as measured by comparison with the addition of measured amounts of hydrogen peroxide to the FBX dosimeter. Atmospheric-pressure plasma jets using nitrogen as a feed gas have a greater oxidizing effect with a high level of humidity added to the feed gas.

Evolution of Spark plasma using nitrogen laser shadowgraphy system

International Nuclear Information System (INIS)

Ishiekwene, G.C.

1994-07-01

A simple, low cost, home built high power nitrogen laser is used as the light source for a shadowgraphy system. A series of shadowgrams depicting the temporal growth of a spark plasma discharge is obtained. The results could be useful in plasma diagnostic studies. (author). 5 refs, 6 figs

Comparison study of nitrogen and argon processing in a plasma arc centrifugal treatment system

International Nuclear Information System (INIS)

Shuey, M.; Tsuji, Y.

2000-01-01

Recent testing performed at the plasma research center of Retech Services, Inc. compared nitrogen with argon as plasma gas in the processing of simulated wastes. The testing took place in a full-scale production PACT system under a cooperative research and development study between Retech Services Inc. and Toyo Engineering Corporation. This study shows that simulated waste can be processed by both nitrogen and argon plasmas. Heat losses to the torch nozzle were significantly lower with argon and should be studied further. Both argon and nitrogen plasma were able to process feeds containing both metals and oxides. Some of the drawbacks to using argon plasma are cost, higher volume flow rates, and dual mode torch nozzle erosion. (authors)

Nitrogen-doped graphene by microwave plasma chemical vapor deposition

International Nuclear Information System (INIS)

Kumar, A.; Voevodin, A.A.; Paul, R.; Altfeder, I.; Zemlyanov, D.; Zakharov, D.N.; Fisher, T.S.

2013-01-01

Rapid synthesis of nitrogen-doped, few-layer graphene films on Cu foil is achieved by microwave plasma chemical vapor deposition. The films are doped during synthesis by introduction of nitrogen gas in the reactor. Raman spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy and scanning tunneling microscopy reveal crystal structure and chemical characteristics. Nitrogen concentrations up to 2 at.% are observed, and the limit is linked to the rigidity of graphene films on copper surfaces that impedes further nitrogen substitutions of carbon atoms. The entire growth process requires only a few minutes without supplemental substrate heating and offers a promising path toward large-scale synthesis of nitrogen-doped graphene films. - Highlights: ► Rapid synthesis of nitrogen doped few layer graphene on Cu foil. ► Defect density increment on 2% nitrogen doping. ► Nitrogen doped graphene is a good protection to the copper metallic surface

Nitrogen-doped graphene by microwave plasma chemical vapor deposition

Energy Technology Data Exchange (ETDEWEB)

Kumar, A., E-mail: kumar50@purdue.edu [Birck Nanotechnolgy Center, Purdue University, West Lafayette, IN 47907 (United States); Voevodin, A.A. [Birck Nanotechnolgy Center, Purdue University, West Lafayette, IN 47907 (United States); Materials and Manufacturing Directorate, Air Force Research Laboratory, WPAFB, OH 45433 (United States); Paul, R. [Birck Nanotechnolgy Center, Purdue University, West Lafayette, IN 47907 (United States); Altfeder, I. [Materials and Manufacturing Directorate, Air Force Research Laboratory, WPAFB, OH 45433 (United States); Zemlyanov, D.; Zakharov, D.N. [Birck Nanotechnolgy Center, Purdue University, West Lafayette, IN 47907 (United States); Fisher, T.S., E-mail: tsfisher@purdue.edu [Birck Nanotechnolgy Center, Purdue University, West Lafayette, IN 47907 (United States); Materials and Manufacturing Directorate, Air Force Research Laboratory, WPAFB, OH 45433 (United States)

2013-01-01

Rapid synthesis of nitrogen-doped, few-layer graphene films on Cu foil is achieved by microwave plasma chemical vapor deposition. The films are doped during synthesis by introduction of nitrogen gas in the reactor. Raman spectroscopy, X-ray photoelectron spectroscopy, transmission electron microscopy and scanning tunneling microscopy reveal crystal structure and chemical characteristics. Nitrogen concentrations up to 2 at.% are observed, and the limit is linked to the rigidity of graphene films on copper surfaces that impedes further nitrogen substitutions of carbon atoms. The entire growth process requires only a few minutes without supplemental substrate heating and offers a promising path toward large-scale synthesis of nitrogen-doped graphene films. - Highlights: ► Rapid synthesis of nitrogen doped few layer graphene on Cu foil. ► Defect density increment on 2% nitrogen doping. ► Nitrogen doped graphene is a good protection to the copper metallic surface.

Deviation from normal Boltzmann distribution of high-lying energy levels of iron atom excited by Okamoto-cavity microwave-induced plasmas using pure nitrogen and nitrogen–oxygen gases

International Nuclear Information System (INIS)

Wagatsuma, Kazuaki

2015-01-01

This paper describes several interesting excitation phenomena occurring in a microwave-induced plasma (MIP) excited with Okamoto-cavity, especially when a small amount of oxygen was mixed with nitrogen matrix in the composition of the plasma gas. An ion-to-atom ratio of iron, which was estimated from the intensity ratio of ion to atomic lines having almost the same excitation energy, was reduced by adding oxygen gas to the nitrogen MIP, eventually contributing to an enhancement in the emission intensities of the atomic lines. Furthermore, Boltzmann plots for iron atomic lines were observed in a wide range of the excitation energy from 3.4 to 6.9 eV, indicating that plots of the atomic lines having lower excitation energies (3.4 to 4.8 eV) were well fitted on a straight line while those having more than 5.5 eV deviated upwards from the linear relationship. This overpopulation would result from any other excitation process in addition to the thermal excitation that principally determines the Boltzmann distribution. A Penning-type collision with excited species of nitrogen molecules probably explains this additional excitation mechanism, in which the resulting iron ions recombine with captured electrons, followed by cascade de-excitations between closely-spaced excited levels just below the ionization limit. As a result, these high-lying levels might be more populated than the low-lying levels of iron atom. The ionization of iron would be caused less actively in the nitrogen–oxygen plasma than in a pure nitrogen plasma, because excited species of nitrogen molecule, which can provide the ionization energy in a collision with iron atom, are consumed through collisions with oxygen molecules to cause their dissociation. It was also observed that the overpopulation occurred to a lesser extent when oxygen gas was added to the nitrogen plasma. The reason for this was also attributed to decreased number density of the excited nitrogen species due to collisions with oxygen

Development of bio/blood compatible polypropylene through low pressure nitrogen plasma surface modification

International Nuclear Information System (INIS)

Gomathi, N.; Rajasekar, R.; Babu, R. Rajesh; Mishra, Debasish; Neogi, S.

2012-01-01

Surface modification of polypropylene by nitrogen containing plasma was performed in this work in order to improve the wettability which resulted in enhanced biocompatibility and blood compatibility. Various nitrogen containing functional groups as well as oxygen containing functional groups were found to be incorporated to the polymer surface during plasma treatment and post plasma reaction respectively. Wettability of the polymers was evaluated by static contact angle measurement to show the improvement in hydrophilicity of plasma treated polypropylene. Cross linking and surface modification were reported to be dominating in the case of nitrogen plasma treatment compared to degradation. The effect of various process variables namely power, pressure, flow rate and treatment time on surface energy and weight loss was studied at various levels according to the central composite design of response surface methodology (RSM). Except pressure the other variables resulted in increased weight loss due to etching whereas with increasing pressure weight loss was found to increase and then decrease. The effect of process variables on surface morphology of polymers was evaluated by Scanning Electron Microscopy (SEM) and Atomic Force Microscopy (AFM). Well spread fibroblast cells on nitrogen plasma treated polypropylene due to the presence of CO, NH 2+ and NH + was observed. Reduced platelet adhesion and increased partial thromboplastin time evidenced the increased blood compatibility. - Highlights: ► Improved biocompatibility and blood compatibility of polypropylene. ► Nitrogen plasma surface modification. ► Maintaining a balance between polar group incorporation and weight loss due to etching. ► Optimization of process conditions by response surface methodology.

Enhancement of electron field emission of vertically aligned carbon nanotubes by nitrogen plasma treatment

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); Plasma Nanoscience Centre Australia (PNCA), CSIRO Materials Science and Engineering, P.O. Box 218, Lindfield, NSW 2070 (Australia); Cheng, Q.J. [Plasma Nanoscience Centre Australia (PNCA), CSIRO Materials Science and Engineering, P.O. Box 218, Lindfield, NSW 2070 (Australia); Plasma Nanoscience, School of Physics, University of Sydney, Sydney, NSW 2006 (Australia); Chen, X. [College of Materials Science and Engineering, Chongqing University, Chongqing 400044 (China); Ostrikov, K., E-mail: kostya.ostrikov@csiro.au [Plasma Nanoscience Centre Australia (PNCA), CSIRO Materials Science and Engineering, P.O. Box 218, Lindfield, NSW 2070 (Australia); Plasma Nanoscience, School of Physics, University of Sydney, Sydney, NSW 2006 (Australia)

2011-09-22

Highlights: > A new and custom-designed bias-enhanced hot-filament chemical vapor deposition system is developed to synthesize vertically aligned carbon nanotubes. > The carbon nanotubes are later treated with nitrogen plasmas. > The electron field emission characteristics of the carbon nanotubes are significantly improved after the nitrogen plasma treatment. > A new physical mechanism is proposed to interpret the improvement of the field emission characteristics. - Abstract: The electron field emission (EFE) characteristics from vertically aligned carbon nanotubes (VACNTs) without and with treatment by the nitrogen plasma are investigated. The VACNTs with the plasma treatment showed a significant improvement in the EFE property compared to the untreated VACNTs. The morphological, structural, and compositional properties of the VACNTs are extensively examined by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and energy dispersive X-ray spectroscopy. It is shown that the significant EFE improvement of the VACNTs after the nitrogen plasma treatment is closely related to the variation of the morphological and structural properties of the VACNTs. The high current density (299.6 {mu}A/cm{sup 2}) achieved at a low applied field (3.50 V/{mu}m) suggests that the VACNTs after nitrogen plasma treatment can serve as effective electron field emission sources for numerous applications.

Enhancement of electron field emission of vertically aligned carbon nanotubes by nitrogen plasma treatment

International Nuclear Information System (INIS)

Wang, B.B.; Cheng, Q.J.; Chen, X.; Ostrikov, K.

2011-01-01

Highlights: → A new and custom-designed bias-enhanced hot-filament chemical vapor deposition system is developed to synthesize vertically aligned carbon nanotubes. → The carbon nanotubes are later treated with nitrogen plasmas. → The electron field emission characteristics of the carbon nanotubes are significantly improved after the nitrogen plasma treatment. → A new physical mechanism is proposed to interpret the improvement of the field emission characteristics. - Abstract: The electron field emission (EFE) characteristics from vertically aligned carbon nanotubes (VACNTs) without and with treatment by the nitrogen plasma are investigated. The VACNTs with the plasma treatment showed a significant improvement in the EFE property compared to the untreated VACNTs. The morphological, structural, and compositional properties of the VACNTs are extensively examined by scanning electron microscopy, transmission electron microscopy, Raman spectroscopy, and energy dispersive X-ray spectroscopy. It is shown that the significant EFE improvement of the VACNTs after the nitrogen plasma treatment is closely related to the variation of the morphological and structural properties of the VACNTs. The high current density (299.6 μA/cm 2 ) achieved at a low applied field (3.50 V/μm) suggests that the VACNTs after nitrogen plasma treatment can serve as effective electron field emission sources for numerous applications.

Non-equilibrium nitrogen DC-arc plasma treatment of TiO2 nanopowder.

Science.gov (United States)

Suzuki, Yoshikazu; Gonzalez-Aguilar, José; Traisnel, Noel; Berger, Marie-Hélène; Repoux, Monique; Fulcheri, Laurent

2009-01-01

Non-equilibrium nitrogen DC-arc plasma treatment of a commercial TiO2 anatase nanopowder was examined to obtain nitrogen-doped TiO2. By using a non-thermal discharge at low current (150 mA) and high voltage (1200 V) using pure N2 gas, light yellowish-gray TiO2 powder was successfully obtained within a short period of 5-10 min. XPS and TEM-EELS studies confirmed the existence of doped nitrogen. Due to the relatively mild conditions (plasma power of 180 W), metastable anatase structure and fine crystallite size of TiO2 (ca. 10 nm) were maintained after the plasma treatment. The in-flight powder treatment system used in this study is promising for various type of powder treatment.

Interaction of Intense Lasers with Plasmas

Science.gov (United States)

Shvets, Gennady

1995-01-01

This thesis addresses two important topics in nonlinear laser plasma physics: the interaction of intense lasers with a non thermal homogeneous plasma, the excitation of laser wakefields in hollow plasma channels, and the stability of channel guided propagation of laser pulses. In the first half of this thesis a new theoretical approach to the nonlinear interaction of intense laser pulses with underdense plasmas is developed. Unlike previous treatments, this theory is three-dimensional, relativistically covariant, and does not assume that astudied. An experimental check of this calculation is suggested, based on the predicted non-linear polarization rotation (the second harmonic is emitted polarized perpendicularly to polarization of the incident signal). The concept of renormalization is applied to the plasma and electromagnetic radiation (photons and plasmons). To the lowest order, this corresponds to relativistically correcting the electron mass for its oscillation in an intense EM field and to replacing the vacuum dispersion relation by the usual relativistic plasma dispersion relation. This renormalization procedure is then carried to higher order in epsilon=omega_sp{p} {2}a^2/[(1+a^2/2)^ {3/2}omega^2]. This yields the nonlinear modification of the index of refraction of a strong electromagnetic wave and the dispersion of a weak probe in the presence of the wave. In the second part of this thesis the stability of short laser pulses propagating through parabolic channels and the wake excitation of hollow plasma channels are studied. The stability of a channel guided short laser pulse propagation is analyzed for the first time. Perturbations to the laser pulse are shown to modify the ponderomotive pressure, which distorts the dielectric properties of the plasma channel. The channel perturbation then further distorts the laser pulse. A set of coupled mode equations is derived, and a matrix dispersion relation is obtained analytically. The ponderomotive excitation

Moderate plasma treatment enhances the quality of optically detected magnetic resonance signals of nitrogen-vacancy centres in nanodiamonds

Science.gov (United States)

Sotoma, Shingo; Igarashi, Ryuji; Shirakawa, Masahiro

2016-05-01

We demonstrate that a moderate plasma treatment increases the quality of optically detected magnetic resonance (ODMR) signals from negatively charged nitrogen-vacancy centres in nanodiamonds (NDs). We measured the statistics of the ODMR spectra of 50-nm-size NDs before and after plasma treatment. We then evaluated each ODMR spectrum in terms of fluorescence and ODMR intensities, line width and signal-to-noise (SN) ratio. Our results showed that plasma treatment for more than 10 min contributes to higher-quality ODMR signals, i.e. signals that are brighter, stronger, sharper and have a higher SN ratio. We showed that such signal improvement is due to alteration of the surface chemical states of the NDs by the plasma treatment. Our study contributes to the advancement of biosensing applications using ODMR of NDs.

The influence of nitrogen entrainment on argon plasmas created by the 'Torche à Injection Axiale' (TIA)

NARCIS (Netherlands)

Jonkers, J.; Hartgers, A.; Selen, L.J.M.; Mullen, van der J.J.A.M.; Schram, D.C.

1999-01-01

When a plasma is sustained in the open air, nitrogen will diffuse into the plasma. Especially for plasmas sustained by the `Torche à Injection Axiale' (TIA) this appears to be the case, since this turbulent jet draws gases from the surroundings. In the argon plasma the entrained nitrogen is probably

Experimental evidence and theoretical analysis of photoionized plasma under x-ray radiation produced by an intense laser

International Nuclear Information System (INIS)

Wang Feilu; Fujioka, Shinsuke; Nishimura, Hiroaki; Takabe, Hideaki; Kato, Daiji; Li Yutong; Zhao Gang; Zhang Jie

2008-01-01

Photoionized plasma was studied experimentally under laboratory conditions by means of high intensity short pulse lasers. The experiment consists of a gold cavity filled with nitrogen gas. Six laser beams were focused on the inner surface of the gold cavity, thereby generating an almost black-body radiation having temperature of 80 eV inside the cavity. This radiation heats the nitrogen gas mainly by means of photoionization. L-shell emissions from N V to N VII have been observed in the wavelength range between 90 and 200 A. A time-dependent Detailed Configuration Accounting computer program has been developed to analyze the experimental spectra. In contrast to standard analysis of astrophysical observations, the evidence for photoionization is inferred from the spectral lines ratios. Comparison between the experimental and simulated line spectra indicates that the radiation heated nitrogen attains temperature of 20-30 eV, much lower than the source radiation temperature. Paradoxically, it is also shown that similar line emissions can be reproduced computationally also when the radiation and plasma temperatures both equal approximately 60 eV. This misleading result indicates that experimental simulation in laboratory is sometimes necessary to avoid misinterpretation of astrophysical spectra.

Study on the surface of fluorosilicone acrylate RGP contact lens treated by low-temperature nitrogen plasma

International Nuclear Information System (INIS)

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

2008-01-01

In order to improve the surface hydrophilicity of fluorosilicone acrylate rigid gas permeable (RGP) contact lens, low temperature nitrogen plasma was used to modify the lens surface. Effects of plasma conditions on the surface structures and properties were investigated. Results indicated that the surface hydrophilicity of RGP contact lens was significantly improved after treatment. X-ray photoelectron spectroscopy (XPS) results showed that the nitrogen element was successfully incorporated into the surface. Furthermore, some new bonds such as N-C=O, F - and silicate were formed on the lens surface after nitrogen plasma treatment, which could result in the improvement of the surface hydrophilicity. Scanning electronic microscope (SEM) results indicated that nitrogen plasma with moderate power could make the surface smoother in some degree, while plasma with higher power could etch the surface

Line intensities for diagnosing laser-produced plasmas

International Nuclear Information System (INIS)

Kauffman, R.L.; Matthews, D.L.; Lee, R.W.; Whitten, B.L.; Kilkenny, J.D.

1983-01-01

We have measured relative line intensities of the K x-ray spectra of Si, Cl, and Ca from laser-produced plasmas to assess their usefulness as a plasma diagnostic. The different elements are added at low concentrations to CH disks which are irradiated at 5 x 10 14 W/cm 2 with a 0.53 μm laser pulse of 20 Joules at 1 nsec. The concentration of each element is kept low in order not to change the Z of the plasma, and therefore the plasma dynamics. The various spectra are measured with a time-resolved spectrograph to obtain line intensities as a function of time over the length of the laser pulse. These relative intensities of various He-like and H-like lines are compared with calculations from a steady-state level population code. The results give good consistency among the various line ratios. Agreement is not as good for analysis of the Li-like satellite lines. Modelling of the Li-like lines need further investigation. 10 references, 9 figures

Evaluation on nitrogen oxides and nanoparticle removal and nitrogen monoxide generation using a wet-type nonthermal plasma reactor

Science.gov (United States)

Takehana, Kotaro; Kuroki, Tomoyuki; Okubo, Masaaki

2018-05-01

Nitrogen oxides (NOx) emitted from power plants and combustion sources cause air pollution problems. Selective catalytic reduction technology is remarkably useful for NOx removal. However, there are several drawbacks such as preparation of reducing agents, usage of harmful heavy metals, and higher cost. On the other hand, trace NO is a vasodilator agent and employed in inhalation therapies for treating pulmonary hypertension in humans. Considering these factors, in the present study, a wet-type nonthermal plasma reactor, which can control NOx and nanoparticle emissions and generate NO, is investigated. The fundamental characteristics of the reactor are investigated. First, the experiment of nanoparticle removal is carried out. Collection efficiencies of over 99% are achieved for nanoparticles at 50 and 100 ml min‑1 of liquid flow rates. Second, experiments of NOx removal under air atmosphere and NOx generation under nitrogen atmosphere are carried out. NOx-removal efficiencies of over 95% under the air plasma are achieved in 50–200 ml min‑1 liquid flow rates. Moreover, under nitrogen plasma, NOx is generated, of which the major portion is NO. For example, NO concentration is 25 ppm, while NOx concentration is 31 ppm at 50 ml min‑1 liquid flow rate. Finally, experiments of NO generation under the nitrogen atmosphere with or without flowing water are carried out. When water flows on the inner surface of the reactor, approximately 14 ppm of NO is generated. Therefore, NO generation requires flowing water. It is considered that the reaction of N and OH, which is similar to the extended Zeldovich mechanism, could occur to induce NO formation. From these results, it is verified that the wet-type plasma reactor is useful for NOx removal and NO generation under nitrogen atmosphere with flowing water.

Ultrafast absorption of intense x rays by nitrogen molecules

Energy Technology Data Exchange (ETDEWEB)

Buth, Christian [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany); PULSE Institute for Ultrafast Energy Science, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Department of Physics and Astronomy, Louisiana State University, Baton Rouge, Louisiana 70803 (United States); Argonne National Laboratory, Argonne, Illinois 60439 (United States); Liu Jicai [Max-Planck-Institut fuer Kernphysik, Saupfercheckweg 1, 69117 Heidelberg (Germany); Department of Mathematics and Physics, North China Electric Power University, 102206 Beijing (China); Chen, Mau Hsiung [Physics Division, Lawrence Livermore National Laboratory, Livermore, California 94550 (United States); Cryan, James P. [PULSE Institute for Ultrafast Energy Science, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Department of Physics, Stanford University, Stanford, California 94305 (United States); Fang Li; Hoener, Matthias; Berrah, Nora [Department of Physics, Western Michigan University, Kalamazoo, Michigan 49008 (United States); Glownia, James M. [PULSE Institute for Ultrafast Energy Science, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Department of Applied Physics, Stanford University, Stanford, California 94305 (United States); Coffee, Ryan N. [PULSE Institute for Ultrafast Energy Science, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States); Linac Coherent Light Source, SLAC National Accelerator Laboratory, Menlo Park, California 94025 (United States)

2012-06-07

We devise a theoretical description for the response of nitrogen molecules (N{sub 2}) to ultrashort and intense x rays from the free electron laser Linac Coherent Light Source (LCLS). We set out from a rate-equation description for the x-ray absorption by a nitrogen atom. The equations are formulated using all one-x-ray-photon absorption cross sections and the Auger and radiative decay widths of multiply-ionized nitrogen atoms. Cross sections are obtained with a one-electron theory and decay widths are determined from ab initio computations using the Dirac-Hartree-Slater (DHS) method. We also calculate all binding and transition energies of nitrogen atoms in all charge states with the DHS method as the difference of two self-consistent field (SCF) calculations ({Delta}SCF method). To describe the interaction with N{sub 2}, a detailed investigation of intense x-ray-induced ionization and molecular fragmentation are carried out. As a figure of merit, we calculate ion yields and the average charge state measured in recent experiments at the LCLS. We use a series of phenomenological models of increasing sophistication to unravel the mechanisms of the interaction of x rays with N{sub 2}: a single atom, a symmetric-sharing model, and a fragmentation-matrix model are developed. The role of the formation and decay of single and double core holes, the metastable states of N{sub 2}{sup 2+}, and molecular fragmentation are explained.

Formation of Nitrogen Oxides in an Apokamp-Type Plasma Source

Science.gov (United States)

Sosnin, É. A.; Goltsova, P. A.; Panarin, V. A.; Skakun, V. S.; Tarasenko, V. F.; Didenko, M. V.

2017-08-01

Using optical and chemical processes, the composition of the products of decay of the atmospheric-pressure non-equilibrium plasma is determined in a pulsed, high-voltage discharge in the modes of apokampic and corona discharges. It is shown that the products of decay primarily contain nitrogen oxides NO x, and in the mode of the corona discharge - ozone. Potential applications of this source of plasma are discussed with respect to plasma processing of the seeds of agricultural crops.

Heating of underdense plasmas by intense lasers

International Nuclear Information System (INIS)

Kruer, W.L.

1972-08-01

In this note we show that two intense driving fields with frequency much greater than the electron plasma frequency (ω/sub pe/), but with a frequency separation of nearly ω/sub pe/, will couple electron and ion plasma waves and drive them unstable. 6 refs

Construction of control and instrumentation devices of high voltage power supply of double chamber plasma nitrogen

International Nuclear Information System (INIS)

Saminto; Eko Priyono; Sugeng Riyanto

2013-01-01

A control and instrumentation devices of high voltage power supply of double chamber plasma nitrogen have been made. This device consists of the software and hardware component. Hardware component consists of SCR phase angle controller LPC-50HDA type, T100MD1616+ PLC, high voltage transformer and voltage rectifier system. Software component used a LADDER program and TBasic serves to control of the high voltage output. The components in these devices have been tested in the double chamber plasma nitrogen. Its performance meet with the design criteria that can supply of plasma nitrogen operation voltage in the range 290 Vdc to 851 Vdc with glow discharge current 0.4 A to 1.4 A. In general it can be said that the control and instrumentation devices of high voltage power supply is ready for use at the double chamber plasma nitrogen device. (author)

Intense ion beam neutralization using underdense background plasma

Energy Technology Data Exchange (ETDEWEB)

Berdanier, William [Department of Physics, The University of Texas at Austin, Austin, Texas 78712 (United States); Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States); Roy, Prabir K. [Lawrence Berkeley National Laboratory, Berkeley, California 94720 (United States); Kaganovich, Igor [Princeton Plasma Physics Laboratory, Princeton University, Princeton, New Jersey 08543 (United States)

2015-01-15

Producing an overdense background plasma for neutralization purposes with a density that is high compared to the beam density is not always experimentally possible. We show that even an underdense background plasma with a small relative density can achieve high neutralization of intense ion beam pulses. Using particle-in-cell simulations, we show that if the total plasma electron charge is not sufficient to neutralize the beam charge, electron emitters are necessary for effective neutralization but are not needed if the plasma volume is so large that the total available charge in the electrons exceeds that of the ion beam. Several regimes of possible underdense/tenuous neutralization plasma densities are investigated with and without electron emitters or dense plasma at periphery regions, including the case of electron emitters without plasma, which does not effectively neutralize the beam. Over 95% neutralization is achieved for even very underdense background plasma with plasma density 1/15th the beam density. We compare results of particle-in-cell simulations with an analytic model of neutralization and find close agreement with the particle-in-cell simulations. Further, we show experimental data from the National Drift Compression experiment-II group that verifies the result that underdense plasma can neutralize intense heavy ion beams effectively.

Fabrication of spherical high-nitrogen stainless steel powder alloys by mechanical alloying and thermal plasma spheroidization

Science.gov (United States)

Razumov, Nikolay G.; Wang, Qing Sheng; Popovich, Anatoly A.; Shamshurin, Aleksey I.

2018-04-01

This paper describes the results of experimental studies on the treatment of Fe-23Cr-11Mn-1N high-nitrogen stainless steel powder alloys, synthesized by the mechanical alloying (MA) of elemental powders in the flow of a radio frequency thermal plasma. The as-milled powder with irregular particles were successfully converted into spherical high-nitrogen stainless steel powder alloy. Measurement of the residual nitrogen content in the obtained powder, shown that during the plasma spheroidization process, part of the nitrogen escapes from the alloy.

Nitrogen Fixation by Gliding Arc Plasma: Better Insight by Chemical Kinetics Modelling.

Science.gov (United States)

Wang, Weizong; Patil, Bhaskar; Heijkers, Stjin; Hessel, Volker; Bogaerts, Annemie

2017-05-22

The conversion of atmospheric nitrogen into valuable compounds, that is, so-called nitrogen fixation, is gaining increased interest, owing to the essential role in the nitrogen cycle of the biosphere. Plasma technology, and more specifically gliding arc plasma, has great potential in this area, but little is known about the underlying mechanisms. Therefore, we developed a detailed chemical kinetics model for a pulsed-power gliding-arc reactor operating at atmospheric pressure for nitrogen oxide synthesis. Experiments are performed to validate the model and reasonable agreement is reached between the calculated and measured NO and NO 2 yields and the corresponding energy efficiency for NO x formation for different N 2 /O 2 ratios, indicating that the model can provide a realistic picture of the plasma chemistry. Therefore, we can use the model to investigate the reaction pathways for the formation and loss of NO x . The results indicate that vibrational excitation of N 2 in the gliding arc contributes significantly to activating the N 2 molecules, and leads to an energy efficient way of NO x production, compared to the thermal process. Based on the underlying chemistry, the model allows us to propose solutions on how to further improve the NO x formation by gliding arc technology. Although the energy efficiency of the gliding-arc-based nitrogen fixation process at the present stage is not comparable to the world-scale Haber-Bosch process, we believe our study helps us to come up with more realistic scenarios of entering a cutting-edge innovation in new business cases for the decentralised production of fertilisers for agriculture, in which low-temperature plasma technology might play an important role. © 2017 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Dynamics of intense laser channel formation in an underdense plasma

International Nuclear Information System (INIS)

Davis, J.; Petrov, G.M.; Velikovich, A.L.

2005-01-01

Efficient guiding and propagation of multi-keV x-rays in plasmas can be achieved by dynamically modifying the media through plasma channel formation. The dynamics of plasma channel formation is studied in preformed underdense plasma irradiated by a high intensity laser. This is done by a two-dimensional model coupling laser propagation to a relativistic particle-in-cell model. For laser intensity of 10 20 W/cm 2 and a laser beam width of 5 μm the channel formation proceeds on a time scale of 60-70 fs in uniform plasma with density 10 18 cm -3 . The channel closes shortly after the rear of the laser pulse has passed due to Coulomb attraction from the ion core. Electron cavitation occurs only if the laser intensity is above a certain threshold intensity and the laser pulse duration exceeds 100 fs. X-ray generation and propagation is feasible for ultrarelativistic laser pulses with small beam width, less than ∼20 μm, and duration of more than 100 fs

Scaling Laws of Nitrogen Soft X-Ray Yields from 1 to 200 kJ Plasma Focus

International Nuclear Information System (INIS)

Akel, M.; Lee, S.

2013-01-01

Numerical experiments are carried out systematically to determine the nitrogen soft x-ray yield for optimized nitrogen plasma focus with storage energy E 0 from 1 kJ to 200 kJ. Scaling laws on nitrogen soft x-ray yield, in terms of storage energies E 0 , peak discharge current I p eak and focus pinch current I p inch were found. It was found that the nitrogen x-ray yields scales on average with y s xr, N= 1.93xE o 1 .21 J (E 0 in kJ) with the scaling showing gradual deterioration as E 0 rises over the range. A more robust scaling is y s xr = 8x10 - 8I 0 3.38 p inch . The optimum nitrogen soft x-ray yield emitted from plasma focus is found to be about 1 kJ for storage energy of 200 kJ. This indicates that nitrogen plasma focus is a good water-window soft x-ray source when properly designed. (author)

Surface modification of polyacrylonitrile co-polymer membranes using pulsed direct current nitrogen plasma

Energy Technology Data Exchange (ETDEWEB)

Pal, Dipankar; Neogi, Sudarsan; De, Sirshendu, E-mail: sde@che.iitkgp.ernet.in

2015-12-31

Low temperature plasma treatment using pulsed direct current discharge of nitrogen gas was employed to enhance hydrophilicity of the polyacrylonitrile co-polymer membranes. The membranes were characterized in terms of morphology, structure, hydrophilicity, and membrane performance. Properties and functional groups on the surface of polyacrylonitrile co-polymer membranes were investigated by contact angle, scanning electron microscopy, Fourier transform infrared and X-ray photoelectron spectroscopy. Effects of plasma conditions, namely, pulsed voltage, duty cycle and treatment time on increase in membrane hydrophilicity were studied. Permeability of treated membrane was increased by 47% and it was retained up to 70 days. Surface etching due to plasma treatment was confirmed by weight loss of the treated membranes. Due to surface etching, average pore size increased and rejection of 200 kDa polyethylene glycol decreased to about 70% for the treated membrane. Oxygen and nitrogen functional groups were responsible for surface hydrophilicity. - Highlights: • Surface modification of polyacrylonitrile co-polymer membranes by pulsed direct current nitrogen plasma • Hydrophilic functional groups incorporated on the membrane surface • Significant enhancement of the permeability and wettability of the membranes • Water contact angle increased with storage time and finally stabilized.

Surface modification of polyacrylonitrile co-polymer membranes using pulsed direct current nitrogen plasma

International Nuclear Information System (INIS)

Pal, Dipankar; Neogi, Sudarsan; De, Sirshendu

2015-01-01

Low temperature plasma treatment using pulsed direct current discharge of nitrogen gas was employed to enhance hydrophilicity of the polyacrylonitrile co-polymer membranes. The membranes were characterized in terms of morphology, structure, hydrophilicity, and membrane performance. Properties and functional groups on the surface of polyacrylonitrile co-polymer membranes were investigated by contact angle, scanning electron microscopy, Fourier transform infrared and X-ray photoelectron spectroscopy. Effects of plasma conditions, namely, pulsed voltage, duty cycle and treatment time on increase in membrane hydrophilicity were studied. Permeability of treated membrane was increased by 47% and it was retained up to 70 days. Surface etching due to plasma treatment was confirmed by weight loss of the treated membranes. Due to surface etching, average pore size increased and rejection of 200 kDa polyethylene glycol decreased to about 70% for the treated membrane. Oxygen and nitrogen functional groups were responsible for surface hydrophilicity. - Highlights: • Surface modification of polyacrylonitrile co-polymer membranes by pulsed direct current nitrogen plasma • Hydrophilic functional groups incorporated on the membrane surface • Significant enhancement of the permeability and wettability of the membranes • Water contact angle increased with storage time and finally stabilized.

Ammonia production in nitrogen seeded plasma discharges in ASDEX Upgrade

Energy Technology Data Exchange (ETDEWEB)

Rohde, V., E-mail: Volker.Rohde@ipp.mpg.de; Oberkofler, M.

2015-08-15

In present tokamaks nitrogen seeding is used to reduce the power load onto the divertor tiles. Some fraction of the seeded nitrogen reacts with hydrogen to form ammonia. The behaviour of ammonia in ASDEX Upgrade is studied by mass spectrometry. Injection without plasma shows strong absorption at the inner walls of the vessel and isotope exchange reactions. During nitrogen seeding in H-mode discharges the onset of a saturation of the nitrogen retention is observed. The residual gas consists of strongly deuterated methane and ammonia with almost equal amounts of deuterium and protium. This confirms the role of surface reactions in the ammonia formation. The results are consistent with findings in previous investigations. A numerical decomposition of mass spectra is under development and will be needed for quantitative evaluation of the results obtained.

Particle porosity at plasma are spraying of metals

International Nuclear Information System (INIS)

Petrunichev, V.A.; Koroleva, E.B.; Pushilin, N.P.

1985-01-01

Quantitative dependences of porosity and character of pore distribution in particles of different materials on particle size and composition of atmosphere in a working chamber are studied experimentally as applied to the process of plasma wire sputtering. Wires 1.2 mm in diameter made of tungsten, molybdenum, Kh20N80 alloy, and zirconium served as sputtering materials. It is shown that pore size and character of their distribution in particles of powders obtained by the method of plasma wire sputtering are dependent on sizes of forming particles and determined by conditions of their cooling. Intensive porosity formation is characteristic of wire sputtering in argon plasma with nitrogen additions, but there are critical values of nitrogen concentration in plasma, above which intensive porosity formation in forming particles stops

Simulation of QED effects in ultrahigh intensity laser-plasma interaction

International Nuclear Information System (INIS)

Kostyukov, I.; Nerush, E.

2010-01-01

Complete text of publication follows. Due to an impressive progress in laser technology, laser pulses with peak intensity of nearly 2 x 10 22 W/cm 2 are now available in laboratory. When the matter is irradiated by so intense laser pulses high energy density plasma is produced. Besides of fundamental interest such plasma is the efficient source of particles and radiation with extreme parameters that opens bright perspectives in developments of advanced particle accelerators, next generation of radiation sources, laboratory modelling of astrophysics phenomena etc. Even high laser intensity the radiation reaction and QED effects become important. One of the QED effects, which recently attracts much attention, is the electron-positron plasma creation in strong laser field. The plasma can be produced via electromagnetic cascades: the seeded charged particles is accelerated in the field of counter-propagating laser pulses, then they emit energetic photons, the photons by turn decay in the laser field and create electron-positron pairs. The pair particles accelerated in the laser field produce new generation of the photons and pairs. For self-consistent study of the electron-positron plasma dynamics in the laser field we develop 2D code based on particle-in-cell and Monte-Carlo methods. The electron, positron and photon dynamics as well as evolution of the plasma and laser fields are calculated by PIC technique while photon emission and pair production are calculated by Monte-Carlo method. We simulate pair production in the field of counter-propagating linearly polarized laser pulses. It is shown that for the laser intensity above threshold the plasma production becomes so intense that the laser pulse are strongly absorbed in the plasma. The laser intensity threshold and the rate of laser field absorption are calculated. Acknowledgements. This work has been supported by federal target 'The scientific and scientific-pedagogical personnel of innovation in Russia' and by

Effects of trace of nitrogen on the helium atmospheric pressure plasma jet interacting with a dielectric substrate

Science.gov (United States)

Ning, Wenjun; Dai, Dong; Zhang, Yuhui; Han, Yongxia; Li, Licheng

2018-03-01

Experimental observations and simulation results regarding a pure He atmospheric pressure plasma jet (APPJ) and He  +  N2 APPJs interacting with a downstream dielectric substrate are presented in this paper. Experiments utilizing spatial-temporal imaging show that, in the case of the pure He APPJ, an annular plasma-substrate interaction pattern is formed. With the introduction of N2, the plasma is more uniformly distributed on the substrate surface, appearing a solid interaction pattern. The experimental measurements indicate 0.5% N2 mixture is the optimal condition to achieve the most intense discharge, while the plasma-substrate contact area is slightly reduced by 6.1% in comparison to that of the pure He APPJ. A 2D self-consistent fluid model is constructed to provide insights into the role of the addition of trace of N2 on the discharge dynamics. The discharge morphologies predicated by the model is in principle consistent with the experimental observations. The simulation reveals that the conversion from the annular plasma-substrate interaction pattern to the solid one is attributed to the synthetic effect of the addition of N2 and the presentence of the substrate acting as the cathode to enhance the local electric field. In the solid interaction pattern, the Penning ionization makes a significant contribution to the surface discharge, especially in the afterglow region. The dominant positive ions (N2+ and N4+ ) and the reactive oxygen and nitrogen species including O and N gain remarkable increment in the flux intensity to the central surface, which merits great application potential.

Vibrational, atomical and electronic relaxation in a nitrogen plasma jet

International Nuclear Information System (INIS)

Asselin, P.; Dudeck, M.

1994-07-01

This is a simplified approach of the characterization of a plasma stationary flow in chemical and electronic disequilibrium conditions by Navier-Stokes equations. The INCA code (AMTEC, USA) is a three-dimensional monolithic calculation code. A computer program for a mono-dimensional evolution of the formed species concentrations in a nitrogen plasma, including conservative equations of vibrational and electronic energies in order to deduce the corresponding temperature profiles. (A.B.). 14 refs., 17 figs., 2 tabs

Industrial applications of plasma, microwave and ultrasound techniques : nitrogen-fixation and hydrogenation reactions

NARCIS (Netherlands)

Hessel, V.; Cravotto, G.; Fitzpatrick, P.; Patil, B.S.; Lang, J.; Bonrath, W.

2013-01-01

The MAPSYN project (Microwave, Acoustic and Plasma assisted SYNtheses) aims at nitrogen-fixation reactions intensified by plasma catalysis and selective hydrogenations intensified by microwaves, possibly assisted by ultrasound. Energy efficiency is the key motif of the project and the call of the

Plasma wave excitation by intense microwave transmission from a space vehicle

Science.gov (United States)

Kimura, I.; Matsumoto, H.; Kaya, N.; Miyatake, S.

An impact of intense microwave upon the ionospheric plasma was empirically investigated by an active rocket experiment (MINIX). The rocket carried two high-power (830W) transmitters of 2.45 GHz microwave on the mother section of the rocket. The ionospheric plasma response to the intense microwave was measured by a diagnostic package installed on both mother and daughter sections. The daughter section was separated from the mother with a slow speed of 15 cm/sec. The plasma wave analyzers revealed that various plasma waves are nonlinearly excited by the microwave. Among them, the most intense are electron cyclotron waves, followed by electron plasma waves. Extremely low frequency waves (several tens of Hz) are also found. The results of the data analysis as well as comparative computer simulations are given in this paper.

Study of a recombination X-ray laser scheme in a H-like nitrogen plasma created by optical field induced ionization

International Nuclear Information System (INIS)

Hulin, S.

2001-01-01

Thanks to their high brightness and short wavelength, X ray lasers are interesting diagnostics in many experiments because they can efficiently probe dense plasmas. Furthermore their mono-chromaticity and collimation make them interesting tools in plasma physics but also in many biology or chemistry experiments. The effective use of this diagnostic is mainly depending on its dimensions and cost. For this reason, research on X ray laser is now focused on the reduction of cost and the realization of table-top facilities. One of these research axis, based on the optical field induced ionization (OFI) of the plasma, is presented in this work. An ultra-short (60 fs) high-brightness (10 19 W/cm 2 ) Ti:Sapphire (790 nm) laser is focused into a nitrogen pulsed gas jet. A dense (10 20 cm -3 ) plasma of fully stripped nitrogen is created by the way. During the fast recombination of the plasma some population inversions between levels of principal quantum number 2 and 1 (2.4 nm) and 3 and 2 (13.4 nm) can occur depending on the plasma parameters. The creation of the plasma by OFI, laser-plasma interaction dominated by relativistic self-focusing, and recombination dynamics are studied by numerical simulations on one hand and experiments on the other hand. Temperature measurements and numerical simulations show a strong heating, destructive for the laser scheme, which can be explained by Raman instability growing. Nevertheless plasma X ray emission in the 2-20 nm range show a strong increase with the electronic density of the 13.4 nm line intensity. This behavior is consistent with a laser effect but is not detected on the 2.4 nm transition line. (author)

Relativistic degenerate electron plasma in an intense magnetic field

International Nuclear Information System (INIS)

Delsante, A.E.; Frankel, N.E.

1978-01-01

The dielectric response function for a dense, ultra-degenerate relativistic electron plasma in an intense uniform magnetic field is presented. Dispersion relations for plasma oscillations parallel and perpendicular to the magnetic field are obtained

Effects of low-pressure nitrogen plasma treatment on the surface properties and electrochemical performance of the polyethylene separator used lithium-ion batteries

Science.gov (United States)

Li, Chun; Li, Hsiao-Ling; Li, Chi-Heng; Liu, Yu-Shuan; Sung, Yu-Ching; Huang, Chun

2018-01-01

In this paper, we describe the surface transition of the polyethylene (PE) separator used in lithium-ion batteries treated by low-pressure nitrogen plasma discharge. The nitrogen-plasma-treated PE separator was characterized by contact angle measurement, Fourier transform infrared spectroscopy, X-ray photoelectron spectroscopy, and scanning electron microscopy. The electrochemical performance of the lithium ion batteries fabricated with the nitrogen-plasma-treated separator was also evaluated. Results showed that polar functionalization groups were induced on the PE surface by the nitrogen plasma discharge, causing the surface to become hydrophilic. The increases in surface wettability and surface free energy result in electrolyte retention improvement. Moreover, the nitrogen plasma-treated PE separator leads to superior performance in lithium-ion battery assembly.

Nonlinear Plasma Waves Excitation by Intense Ion Beams in Background Plasma

International Nuclear Information System (INIS)

Kaganovich, Igor D.; Startsev, Edward A.; Davidson, Ronald C.

2004-01-01

Plasma neutralization of an intense ion pulse is of interest for many applications, including plasma lenses, heavy ion fusion, cosmic ray propagation, etc. An analytical electron fluid model has been developed to describe the plasma response to a propagating ion beam. The model predicts very good charge neutralization during quasi-steady-state propagation, provided the beam pulse duration τ b is much longer than the electron plasma period 2π/ω p , where ω p = (4πe 2 n p /m) 1/2 is the electron plasma frequency and n p is the background plasma density. In the opposite limit, the beam pulse excites large-amplitude plasma waves. If the beam density is larger than the background plasma density, the plasma waves break. Theoretical predictions are compared with the results of calculations utilizing a particle-in-cell (PIC) code. The cold electron fluid results agree well with the PIC simulations for ion beam propagation through a background plasma. The reduced fluid description derived in this paper can provide an important benchmark for numerical codes and yield scaling relations for different beam and plasma parameters. The visualization of numerical simulation data shows complex collective phenomena during beam entry and exit from the plasma

Nonlinear plasma waves excitation by intense ion beams in background plasma

International Nuclear Information System (INIS)

Kaganovich, Igor D.; Startsev, Edward A.; Davidson, Ronald C.

2004-01-01

Plasma neutralization of an intense ion pulse is of interest for many applications, including plasma lenses, heavy ion fusion, cosmic ray propagation, etc. An analytical electron fluid model has been developed to describe the plasma response to a propagating ion beam. The model predicts very good charge neutralization during quasi-steady-state propagation, provided the beam pulse duration τ b is much longer than the electron plasma period 2π/ω p , where ω p =(4πe 2 n p /m) 1/2 is the electron plasma frequency, and n p is the background plasma density. In the opposite limit, the beam pulse excites large-amplitude plasma waves. If the beam density is larger than the background plasma density, the plasma waves break. Theoretical predictions are compared with the results of calculations utilizing a particle-in-cell (PIC) code. The cold electron fluid results agree well with the PIC simulations for ion beam propagation through a background plasma. The reduced fluid description derived in this paper can provide an important benchmark for numerical codes and yield scaling relations for different beam and plasma parameters. The visualization of numerical simulation data shows complex collective phenomena during beam entry and exit from the plasma

Intense EM filamentation in relativistic hot plasmas

Energy Technology Data Exchange (ETDEWEB)

Hu, Qiang-Lin [Department of Physics, Jinggangshan University, Ji' an, Jiangxi 343009 (China); Chen, Zhong-Ping [Department of Physics and Institute for Fusion Studies, The University of Texas at Austin, Austin, TX 78712 (United States); Mahajan, Swadesh M., E-mail: mahajan@mail.utexas.edu [Department of Physics and Institute for Fusion Studies, The University of Texas at Austin, Austin, TX 78712 (United States); Department of Physics, School of Natural Sciences, Shiv Nadar University, Uttar Pradesh 201314 (India)

2017-03-03

Highlights: • Breaking up of an intense EM pulse into filaments is a spectacular demonstration of the nonlinear wave-plasma interaction. • Filaments are spectacularly sharper, highly extended and longer lived at relativistic temperatures. • EM energy concentration can trigger new nonlinear phenomena with absolute consequences for high energy density matter. - Abstract: Through 2D particle-in-cell (PIC) simulations, we demonstrate that the nature of filamentation of a high intensity electromagnetic (EM) pulse propagating in an underdense plasma, is profoundly affected at relativistically high temperatures. The “relativistic” filaments are sharper, are dramatically extended (along the direction of propagation), and live much longer than their lower temperature counterparts. The thermally boosted electron inertia is invoked to understand this very interesting and powerful phenomenon.

Plasma discreteness effects in the presence of an intense, ultrashort laser pulse

Energy Technology Data Exchange (ETDEWEB)

Savchenko, V.I.; Fisch, N.J.

1996-03-01

Discrete effects of the plasma irradiated by an ultrashort, intense laser pulse are investigated. Although, for most plasmas of interest, the damping of the laser pulse is due to collective plasma effects, in certain regimes the energy absorbed in the plasma microfields can be important. A scattering matrix is derived for an electron scattering off an ion in the presence of an intense laser field.

Plasma discreteness effects in the presence of an intense, ultrashort laser pulse

International Nuclear Information System (INIS)

Savchenko, V.I.; Fisch, N.J.

1996-03-01

Discrete effects of the plasma irradiated by an ultrashort, intense laser pulse are investigated. Although, for most plasmas of interest, the damping of the laser pulse is due to collective plasma effects, in certain regimes the energy absorbed in the plasma microfields can be important. A scattering matrix is derived for an electron scattering off an ion in the presence of an intense laser field

Plasma mirrors for ultrahigh-intensity optics

Energy Technology Data Exchange (ETDEWEB)

Thaury, C; Quere, F; Levy, A; Ceccotti, T; Monot, P; Bougeard, M; Reau, F; D' Oliveira, P; Martin, PH [CEA, DSM, DRECAM, Serv Photons Atomes and Mol, F-91191 Gif Sur Yvette, (France); Geindre, J P; Audebert, P [Ecole Polytech, CNRS, Lab Utilisat Lasers Inst, F-91128 Palaiseau, (France); Marjoribanks, R [Univ Toronto, Dept Phys, Toronto, ON M5S 1A7, (Canada); Marjoribanks, R [Univ Toronto, Inst Opt Sci, Toronto, ON M5S 1A7, (Canada)

2007-07-01

Specular reflection is one of the most fundamental processes of optics. At moderate light intensities generated by conventional light sources this process is well understood. But at those capable of being produced by modern ultrahigh-intensity lasers, many new and potentially useful phenomena arise. When a pulse from such a laser hits an optically polished surface, it generates a dense plasma that itself acts as a mirror, known as a plasma mirror (PM). PMs do not just reflect the remainder of the incident beam, but can act as active optical elements. Using a set of three consecutive PMs in different regimes, we significantly improve the temporal contrast of femtosecond pulses, and demonstrate that high-order harmonics of the laser frequency can be generated through two distinct mechanisms. A better understanding of these processes should aid the development of laser-driven atto-second sources for use in fields from materials science to molecular biology. (authors)

Plasma mirrors for ultrahigh-intensity optics

International Nuclear Information System (INIS)

Thaury, C.; Quere, F.; Levy, A.; Ceccotti, T.; Monot, P.; Bougeard, M.; Reau, F.; D'Oliveira, P.; Martin, PH.; Geindre, J.P.; Audebert, P.; Marjoribanks, R.; Marjoribanks, R.

2007-01-01

Specular reflection is one of the most fundamental processes of optics. At moderate light intensities generated by conventional light sources this process is well understood. But at those capable of being produced by modern ultrahigh-intensity lasers, many new and potentially useful phenomena arise. When a pulse from such a laser hits an optically polished surface, it generates a dense plasma that itself acts as a mirror, known as a plasma mirror (PM). PMs do not just reflect the remainder of the incident beam, but can act as active optical elements. Using a set of three consecutive PMs in different regimes, we significantly improve the temporal contrast of femtosecond pulses, and demonstrate that high-order harmonics of the laser frequency can be generated through two distinct mechanisms. A better understanding of these processes should aid the development of laser-driven atto-second sources for use in fields from materials science to molecular biology. (authors)

DNA damage in oral cancer cells induced by nitrogen atmospheric pressure plasma jets

Science.gov (United States)

Han, Xu; Klas, Matej; Liu, Yueying; Stack, M. Sharon; Ptasinska, Sylwia

2013-09-01

The nitrogen atmospheric pressure plasma jet (APPJ) has been shown to effectively induce DNA double strand breaks in SCC-25 oral cancer cells. The APPJ source constructed in our laboratory consists of two external electrodes wrapping around a quartz tube and nitrogen as a feed gas and operates based on dielectric barrier gas discharge. Generally, it is more challenging to ignite plasma in N2 atmosphere than in noble gases. However, this design provides additional advantages such as lower costs compared to the noble gases for future clinical operation. Different parameters of the APPJ configuration were tested in order to determine radiation dosage. To explore the effects of delayed damage and cell self-repairing, various incubation times of cells after plasma treatment were also performed. Reactive species generated in plasma jet and in liquid environment are essential to be identified and quantified, with the aim of unfolding the mystery of detailed mechanisms for plasma-induced cell apoptosis. Moreover, from the comparison of plasma treatment effect on normal oral cells OKF6T, an insight to the selectivity for cancer treatment by APPJ can be explored. All of these studies are critical to better understand the damage responses of normal and abnormal cellular systems to plasma radiation, which are useful for the development of advanced plasma therapy for cancer treatment at a later stage.

Plasma urea nitrogen and progesterone concentrations and follicular dynamics in ewes fed proteins of different degradability

Directory of Open Access Journals (Sweden)

Gustavo Bianchi Lazarin

2012-07-01

Full Text Available The effects of overfeeding with protein of different degradability on body condition, plasma urea nitrogen and progesterone concentrations, ovulation number and follicular dynamics were assessed in Santa Ines ewes. Twelve ewes were assigned to a randomized block design according to body weight and received overfeeding with soybean meal or with corn gluten meal or maintenance diet for 28 days before ovulation and during the next estrous cycle. Blood samples were taken on days 7, 14, 21, and 28 after the beginning of treatments for analysis of plasma urea nitrogen and on days 3, 6, 9, 12, and 15 into the estrous cycle for analysis of plasma urea nitrogen and progesterone. Follicular dynamics was monitored daily by ultrasound during one estrous cycle. Dry matter and crude protein intake, weight gain, plasma urea nitrogen concentration before ovulation, number of ovulations, diameter of the largest follicle of the 1st and of the 2nd waves and the growth rate of the largest follicle of the 1st wave were higher in the ewes that received overfeeding. The growth rate of the largest follicle of the 3rd wave was higher in the ewes fed maintenance diet. The back fat thickness, plasma urea nitrogen before ovulation and progesterone concentrations, diameter of the largest follicle of the 2nd wave and growth rate of the largest follicle of the 3rd wave were higher in ewes that received overfeeding with soybean meal. The growth rate of the largest follicle of the 1st wave was higher in ewes that received overfeeding with corn gluten meal. Overfeeding with protein-rich feeds may increase the ovulation number and with soybean meal, it may be effective in increasing plasma progesterone concentration in ewes.

High intensity surface plasma waves, theory and PIC simulations

Science.gov (United States)

Raynaud, M.; Héron, A.; Adam, J.-C.

2018-01-01

With the development of intense (>1019 W cm-2) short pulses (≤25 fs) laser with very high contrast, surface plasma wave (SPW) can be explored in the relativistic regime. As the SPW propagates with a phase velocity close to the speed of light it may results in a strong acceleration of electron bunches along the surface permitting them to reach relativistic energies. This may be important e.g. for applications in the field of plasma-based accelerators. We investigate in this work the excitation of SPWs on grating preformed over-dense plasmas for laser intensities ranging from 1019 up to 1021 W cm-2. We discuss the nature of the interaction with respect to the solid case in which surface plasmon can be resonantly excited with weak laser intensity. In particular, we show the importance of the pulse duration and focalization of the laser beam on the amplitude of the SPW.

Different land use intensities in grassland ecosystems drive ecology of microbial communities involved in nitrogen turnover in soil.

Science.gov (United States)

Meyer, Annabel; Focks, Andreas; Radl, Viviane; Keil, Daniel; Welzl, Gerhard; Schöning, Ingo; Boch, Steffen; Marhan, Sven; Kandeler, Ellen; Schloter, Michael

2013-01-01

Understanding factors driving the ecology of N cycling microbial communities is of central importance for sustainable land use. In this study we report changes of abundance of denitrifiers, nitrifiers and nitrogen-fixing microorganisms (based on qPCR data for selected functional genes) in response to different land use intensity levels and the consequences for potential turnover rates. We investigated selected grassland sites being comparable with respect to soil type and climatic conditions, which have been continuously treated for many years as intensely used meadows (IM), intensely used mown pastures (IP) and extensively used pastures (EP), respectively. The obtained data were linked to above ground biodiversity pattern as well as water extractable fractions of nitrogen and carbon in soil. Shifts in land use intensity changed plant community composition from systems dominated by s-strategists in extensive managed grasslands to c-strategist dominated communities in intensive managed grasslands. Along the different types of land use intensity, the availability of inorganic nitrogen regulated the abundance of bacterial and archaeal ammonia oxidizers. In contrast, the amount of dissolved organic nitrogen determined the abundance of denitrifiers (nirS and nirK). The high abundance of nifH carrying bacteria at intensive managed sites gave evidence that the amounts of substrates as energy source outcompete the high availability of inorganic nitrogen in these sites. Overall, we revealed that abundance and function of microorganisms involved in key processes of inorganic N cycling (nitrification, denitrification and N fixation) might be independently regulated by different abiotic and biotic factors in response to land use intensity.

Different land use intensities in grassland ecosystems drive ecology of microbial communities involved in nitrogen turnover in soil.

Directory of Open Access Journals (Sweden)

Annabel Meyer

Full Text Available Understanding factors driving the ecology of N cycling microbial communities is of central importance for sustainable land use. In this study we report changes of abundance of denitrifiers, nitrifiers and nitrogen-fixing microorganisms (based on qPCR data for selected functional genes in response to different land use intensity levels and the consequences for potential turnover rates. We investigated selected grassland sites being comparable with respect to soil type and climatic conditions, which have been continuously treated for many years as intensely used meadows (IM, intensely used mown pastures (IP and extensively used pastures (EP, respectively. The obtained data were linked to above ground biodiversity pattern as well as water extractable fractions of nitrogen and carbon in soil. Shifts in land use intensity changed plant community composition from systems dominated by s-strategists in extensive managed grasslands to c-strategist dominated communities in intensive managed grasslands. Along the different types of land use intensity, the availability of inorganic nitrogen regulated the abundance of bacterial and archaeal ammonia oxidizers. In contrast, the amount of dissolved organic nitrogen determined the abundance of denitrifiers (nirS and nirK. The high abundance of nifH carrying bacteria at intensive managed sites gave evidence that the amounts of substrates as energy source outcompete the high availability of inorganic nitrogen in these sites. Overall, we revealed that abundance and function of microorganisms involved in key processes of inorganic N cycling (nitrification, denitrification and N fixation might be independently regulated by different abiotic and biotic factors in response to land use intensity.

Different Land Use Intensities in Grassland Ecosystems Drive Ecology of Microbial Communities Involved in Nitrogen Turnover in Soil

Science.gov (United States)

Meyer, Annabel; Focks, Andreas; Radl, Viviane; Keil, Daniel; Welzl, Gerhard; Schöning, Ingo; Boch, Steffen; Marhan, Sven; Kandeler, Ellen; Schloter, Michael

2013-01-01

Understanding factors driving the ecology of N cycling microbial communities is of central importance for sustainable land use. In this study we report changes of abundance of denitrifiers, nitrifiers and nitrogen-fixing microorganisms (based on qPCR data for selected functional genes) in response to different land use intensity levels and the consequences for potential turnover rates. We investigated selected grassland sites being comparable with respect to soil type and climatic conditions, which have been continuously treated for many years as intensely used meadows (IM), intensely used mown pastures (IP) and extensively used pastures (EP), respectively. The obtained data were linked to above ground biodiversity pattern as well as water extractable fractions of nitrogen and carbon in soil. Shifts in land use intensity changed plant community composition from systems dominated by s-strategists in extensive managed grasslands to c-strategist dominated communities in intensive managed grasslands. Along the different types of land use intensity, the availability of inorganic nitrogen regulated the abundance of bacterial and archaeal ammonia oxidizers. In contrast, the amount of dissolved organic nitrogen determined the abundance of denitrifiers (nirS and nirK). The high abundance of nifH carrying bacteria at intensive managed sites gave evidence that the amounts of substrates as energy source outcompete the high availability of inorganic nitrogen in these sites. Overall, we revealed that abundance and function of microorganisms involved in key processes of inorganic N cycling (nitrification, denitrification and N fixation) might be independently regulated by different abiotic and biotic factors in response to land use intensity. PMID:24039974

Numerical simulation of a novel non-transferred arc plasma torch operating with nitrogen

International Nuclear Information System (INIS)

Hiremath, Gavisiddayya; Kandasamy, Ramachandran; Ganesh, Ravi

2015-01-01

High power plasma torches with higher electro-thermal efficiency are required for industrial applications. To increase the plasma power and electrothermal efficiency, conventional torches are being modified to operate with molecular gases such as air and nitrogen. Since increasing arc current enhances the heat loss to the anode, torches are being developed to operate under high voltage and low current. The plasma flow dynamics and electromagnetic coupling with plasma flow inside the torch etc. are highly complex and knowledge on the same is required to develop high torches with higher efficiency. Unfortunately detailed experimentation on the same is very difficult. Numerical modeling and simulation is one of the best tools to understand the physics involved in such complex processes. A 2D numerical model is developed to simulate the characteristics of the plasma inside the torch. Though plasma is not in local thermodynamic equilibrium (LTE) close to the electrodes, LTE is assumed everywhere in the plasma to avoid complex and time consuming calculations. Other valid assumptions used in the model are plasma flow is optically thin, laminar and incompressible. Flow, energy and electromagnetic equations are solved with appropriate boundary conditions and volume sources using SIMPLE algorithm with finite volume method. Temperature dependent thermophysical properties of nitrogen are used for the simulations. Simulations are carried out for different experimental conditions. The effects of arc current, gas flow rate of plasma generating gas and sheath gas injected above the bottom anode on the arc voltage, electrothermal efficiency of the torch, plasma temperature and plasma velocity are simulated. Predicted results are compared with experimental results. (author)

Low light intensity and nitrogen starvation modulate the chlorophyll content of Scenedesmus dimorphus.

Science.gov (United States)

Ferreira, V S; Pinto, R F; Sant'Anna, C

2016-03-01

Chlorophyll is a photosynthetic pigment found in plants and algal organisms and is a bioproduct with human health benefits and a great potential for use in the food industry. The chlorophyll content in microalgae strains varies in response to environmental factors. In this work, we assessed the effect of nitrogen depletion and low light intensity on the chlorophyll content of the Scenedesmus dimorphus microalga. The growth of S. dimorphus under low light intensity led to a reduction in cell growth and volume as well as increased cellular chlorophyll content. Nitrogen starvation led to a reduction in cell growth and the chlorophyll content, changes in the yield and productivity of chlorophylls a and b. Transmission electron microscopy was used to investigate the ultrastructural changes in the S. dimorphus exposed to nitrogen and light deficiency. In contrast to nitrogen depletion, low light availability was an effective mean for increasing the total chlorophyll content of green microalga S. dimorphus. The findings acquired in this work are of great biotechnological importance to extend knowledge of choosing the right culture condition to stimulate the effectiveness of microalgae strains for chlorophyll production purposes. © 2015 The Society for Applied Microbiology.

Plasma Wind Tunnel Investigation of European Ablators in Nitrogen/Methane Using Emission Spectroscopy

Directory of Open Access Journals (Sweden)

Ricarda Wernitz

2013-01-01

Full Text Available For atmospheric reentries at high enthalpies ablative heat shield materials are used, such as those for probes entering the atmosphere of Saturn’s moon Titan, such as Cassini-Huygens in December, 2004. The characterization of such materials in a nitrogen/methane atmosphere is of interest. A European ablative material, AQ60, has been investigated in plasma wind tunnel tests at the IRS plasma wind tunnel PWK1 using the magnetoplasma dynamic generator RD5 as plasma source in a nitrogen/methane atmosphere. The dimensions of the samples are 45 mm in length with a diameter of 39 mm. The actual ablator has a thickness of 40 mm. The ablator is mounted on an aluminium substructure. The experiments were conducted at two different heat flux regimes, 1.4 MW/m2 and 0.3 MW/m2. In this paper, results of emission spectroscopy at these plasma conditions in terms of plasma species’ temperatures will be presented, including the investigation of the free-stream species, N2 and N2+, and the major erosion product C2, at a wavelength range around 500 nm–600 nm.

Analysis of plasma channels in mm-scale plasmas formed by high intensity laser beams

International Nuclear Information System (INIS)

Murakami, R; Habara, H; Iwawaki, T; Uematsu, Y; Tanaka, K A; Ivancic, S; Anderson, K; Haberberger, D; Stoeckl, C; Theobald, W; Sakagami, H

2016-01-01

A plasma channel created by a high intensity infrared laser beam was observed in a long scale-length plasma (L ∼ 240 μm) with the angular filter refractometry technique, which indicated a stable channel formation up to the critical density. We analyzed the observed plasma channel using a rigorous ray-tracing technique, which provides a deep understanding of the evolution of the channel formation. (paper)

Dynamics of plasma ions motion in ultra-intense laser-excited plasma wakes

International Nuclear Information System (INIS)

Zhou Suyun; Li Jing

2013-01-01

The effects of heavy ions and protons motion in an ultra-intense laser-driven plasma wake are compared by rebuilding a plasma wake model. It is shown that with the same laser and plasma background electron density n 0 , the heavy ions' motion suppresses wake-field resonant excitation less than the protons' motion in their own plasma wake. Though heavy ions obtain more kinetic energy from the plasma wake, its energy density is less than that of the protons due to the ion density being far less than the proton density. As a result, the total energy of heavy ions obtained from the wake-field is far less than that of protons. The dependence of the kinetic energy and the energy density of protons and heavy ions on n 0 is discussed. (paper)

Interaction of ultra-short ultra-intense laser pulses with under-dense plasmas; Interaction d'impulsions laser ultra-courtes et ultra-intenses avec des plasmas sous denses

Energy Technology Data Exchange (ETDEWEB)

Solodov, A

2000-12-15

Different aspects of interaction of ultra-short ultra-intense laser pulses with underdense plasmas are studied analytically and numerically. These studies can be interesting for laser-driven electron acceleration in plasma, X-ray lasers, high-order harmonic generation, initial confinement fusion with fast ignition. For numerical simulations a fully-relativistic particle code WAKE was used, developed earlier at Ecole Polytechnique. It was modified during the work on the thesis in the part of simulation of ion motion, test electron motion, diagnostics for the field and plasma. The studies in the thesis cover the problems of photon acceleration in the plasma wake of a short intense laser pulse, phase velocity of the plasma wave in the Self-Modulated Laser Wake-Field Accelerator (SM LWFA), relativistic channeling of laser pulses with duration of the order of a plasma period, ion dynamics in the wake of a short intense laser pulse, plasma wave breaking. Simulation of three experiments on the laser pulse propagation in plasma and electron acceleration were performed. Among the main results of the thesis, it was found that reduction of the plasma wave phase velocity in the SM LWFA is crucial for electron acceleration, only if a plasma channel is used for the laser pulse guiding. Self-similar structures describing relativistic guiding of short laser pulses in plasmas were found and relativistic channeling of initially Gaussian laser pulses of a few plasma periods in duration was demonstrated. It was shown that ponderomotive force of a plasma wake excited by a short laser pulse forms a channel in plasma and plasma wave breaking in the channel was analyzed in detail. Effectiveness of electron acceleration by the laser field and plasma wave was compared and frequency shift of probe laser pulses by the plasma waves was found in conditions relevant to the current experiments. (author)

Nitrate-Nitrogen Leaching and Modeling in Intensive Agriculture Farmland in China

Directory of Open Access Journals (Sweden)

Ligang Xu

2013-01-01

Full Text Available Protecting water resources from nitrate-nitrogen (NO3-N contamination is an important public health concern and a major national environmental issue in China. Loss of NO3-N in soils due to leaching is not only one of the most important problems in agriculture farming, but is also the main factor causing nitrogen pollution in aquatic environments. Three typical intensive agriculture farmlands in Jiangyin City in China are selected as a case study for NO3-N leaching and modeling in the soil profile. In this study, the transport and fate of NO3-N within the soil profile and nitrate leaching to drains were analyzed by comparing field data with the simulation results of the LEACHM model. Comparisons between measured and simulated data indicated that the NO3-N concentrations in the soil and nitrate leaching to drains are controlled by the fertilizer practice, the initial conditions and the rainfall depth and distribution. Moreover, the study reveals that the LEACHM model gives a fair description of the NO3-N dynamics in the soil and subsurface drainage at the field scale. It can also be concluded that the model after calibration is a useful tool to optimize as a function of the combination “climate-crop-soil-bottom boundary condition” the nitrogen application strategy resulting for the environment in an acceptable level of nitrate leaching. The findings in this paper help to demonstrate the distribution and migration of nitrogen in intensive agriculture farmlands, as well as to explore the mechanism of groundwater contamination resulting from agricultural activities.

Nitrate-Nitrogen Leaching and Modeling in Intensive Agriculture Farmland in China

Science.gov (United States)

Xu, Ligang; Xu, Jin

2013-01-01

Protecting water resources from nitrate-nitrogen (NO3-N) contamination is an important public health concern and a major national environmental issue in China. Loss of NO3-N in soils due to leaching is not only one of the most important problems in agriculture farming, but is also the main factor causing nitrogen pollution in aquatic environments. Three typical intensive agriculture farmlands in Jiangyin City in China are selected as a case study for NO3-N leaching and modeling in the soil profile. In this study, the transport and fate of NO3-N within the soil profile and nitrate leaching to drains were analyzed by comparing field data with the simulation results of the LEACHM model. Comparisons between measured and simulated data indicated that the NO3-N concentrations in the soil and nitrate leaching to drains are controlled by the fertilizer practice, the initial conditions and the rainfall depth and distribution. Moreover, the study reveals that the LEACHM model gives a fair description of the NO3-N dynamics in the soil and subsurface drainage at the field scale. It can also be concluded that the model after calibration is a useful tool to optimize as a function of the combination “climate-crop-soil-bottom boundary condition” the nitrogen application strategy resulting for the environment in an acceptable level of nitrate leaching. The findings in this paper help to demonstrate the distribution and migration of nitrogen in intensive agriculture farmlands, as well as to explore the mechanism of groundwater contamination resulting from agricultural activities. PMID:23983629

Simultaneous removal of nitrogen oxide/nitrogen dioxide/sulfur dioxide from gas streams by combined plasma scrubbing technology.

Science.gov (United States)

Chang, Moo Been; Lee, How Ming; Wu, Feeling; Lai, Chi Ren

2004-08-01

Oxides of nitrogen (NOx) [nitrogen oxide (NO) + nitrogen dioxide (NO2)] and sulfur dioxide (SO2) are removed individually in traditional air pollution control technologies. This study proposes a combined plasma scrubbing (CPS) system for simultaneous removal of SO2 and NOx. CPS consists of a dielectric barrier discharge (DBD) and wet scrubbing in series. DBD is used to generate nonthermal plasmas for converting NO to NO2. The water-soluble NO2 then can be removed by wet scrubbing accompanied with SO2 removal. In this work, CPS was tested with simulated exhausts in the laboratory and with diesel-generator exhausts in the field. Experimental results indicate that DBD is very efficient in converting NO to NO2. More than 90% removal of NO, NOx, and SO2 can be simultaneously achieved with CPS. Both sodium sulfide (Na2S) and sodium sulfite (Na2SO3) scrubbing solutions are good for NO2 and SO2 absorption. Energy efficiencies for NOx and SO2 removal are 17 and 18 g/kWh, respectively. The technical feasibility of CPS for simultaneous removal of NO, NO2, and SO2 from gas streams is successfully demonstrated in this study. However, production of carbon monoxide as a side-product (approximately 100 ppm) is found and should be considered.

Intensity-dependent resonant transmission of x-rays in solid-density aluminum plasma

Science.gov (United States)

Cho, M. S.; Chung, H.-K.; Cho, B. I.

2018-05-01

X-ray free-electron lasers (XFELs) provide unique opportunities to generate and investigate dense plasmas. The absorption and transmission properties of x-ray photons in dense plasmas are important in characterizing the state of the plasmas. Experimental evidence shows that the transmission of x-ray photons through dense plasmas depends greatly on the incident XFEL intensity. Here, we present a detailed analysis of intensity-dependent x-ray transmission in solid-density aluminum using collisional-radiative population kinetics calculations. Reverse saturable absorption (RSA), i.e., an increase in x-ray absorption with intensity has been observed for photon energies below the K-absorption edge and in the intensity range of 1016-1017 W/cm2 for XFEL photons with 1487 eV. At higher intensities, a transition from RSA to saturable absorption (SA) is predicted; thus, the x-ray absorption decreases with intensity above a threshold value. For XFEL photon energies of 1501 eV and 1515 eV, the transition from RSA to SA occurs at XFEL intensities between 1017-1018 W/cm2. Electron temperatures are predicted to be in the range of 30-50 eV for the given experimental conditions. Detailed population kinetics of the charge states explains the intensity-dependent absorption of x-ray photons and the fast modulation of XFEL pulses for both RSA and SA.

Development of intense pulsed heavy ion beam diode using gas puff plasma gun as ion source

International Nuclear Information System (INIS)

Ito, H.; Higashiyama, M.; Takata, S.; Kitamura, I.; Masugata, K.

2006-01-01

A magnetically insulated ion diode with an active ion source of a gas puff plasma gun has been developed in order to generate a high-intensity pulsed heavy ion beam for the implantation process of semiconductors and the surface modification of materials. The nitrogen plasma produced by the plasma gun is injected into the acceleration gap of the diode with the external magnetic field system. The ion diode is operated at diode voltage approx. =200 kV, diode current approx. =2 kA and pulse duration approx. =150 ns. A new acceleration gap configuration for focusing ion beam has been designed in order to enhance the ion current density. The experimental results show that the ion current density is enhanced by a factor of 2 and the ion beam has the ion current density of 27 A/cm 2 . In addition, the coaxial type Marx generator with voltage 200 kV and current 15 kA has been developed and installed in the focus type ion diode. The ion beam of ion current density approx. =54 A/cm 2 is obtained. To produce metallic ion beams, an ion source by aluminum wire discharge has been developed and the aluminum plasma of ion current density ∼70 A/cm 2 is measured. (author)

Construction of a nitrogen laser for plasma diagnostics

International Nuclear Information System (INIS)

Ishiekwene, G.C.

1994-07-01

The challenge faced in finding new sources of energy to bridge the gap between the availability and demand of energy is difficult to be overemphasized. Nuclear fusion seems to provide a potentially limitless source of energy which offers a bright prospect for solving this problem. Although an elaborate programme in fusion may be beyond the economic reach of most third world countries, some modest experiments are necessary to provide an indigenous expertise capable of enhancing international fusion studies. In order to initiate experimental research sufficient for plasma studies at an affordable cost to developing countries, this paper illustrates the construction of a simple, low cost, high power nitrogen laser and investigates some of its performance characteristics. Also, the laser is utilized as a source of illumination in the techniques of shadowgraphy. A series of shadowgrams depicting the temporal development of the plasma discharge is presented. The constructed laser is found to be cost-effective and useful in small-scale researches in laser-plasma diagnostics. (author). 6 refs, 5 figs

Direct deposition of aluminum oxide gate dielectric on graphene channel using nitrogen plasma treatment

International Nuclear Information System (INIS)

Lim, Taekyung; Kim, Dongchool; Ju, Sanghyun

2013-01-01

Deposition of high-quality dielectric on a graphene channel is an essential technology to overcome structural constraints for the development of nano-electronic devices. In this study, we investigated a method for directly depositing aluminum oxide (Al 2 O 3 ) on a graphene channel through nitrogen plasma treatment. The deposited Al 2 O 3 thin film on graphene demonstrated excellent dielectric properties with negligible charge trapping and de-trapping in the gate insulator. A top-gate-structural graphene transistor was fabricated using Al 2 O 3 as the gate dielectric with nitrogen plasma treatment on graphene channel region, and exhibited p-type transistor characteristics

Crystal Structures of GaN Nanodots by Nitrogen Plasma Treatment on Ga Metal Droplets

Directory of Open Access Journals (Sweden)

Yang-Zhe Su

2018-06-01

Full Text Available Gallium nitride (GaN is one of important functional materials for optoelectronics and electronics. GaN exists both in equilibrium wurtzite and metastable zinc-blende structural phases. The zinc-blende GaN has superior electronic and optical properties over wurtzite one. In this report, GaN nanodots can be fabricated by Ga metal droplets in ultra-high vacuum and then nitridation by nitrogen plasma. The size, shape, density, and crystal structure of GaN nanodots can be characterized by transmission electron microscopy. The growth parameters, such as pre-nitridation treatment on Si surface, substrate temperature, and plasma nitridation time, affect the crystal structure of GaN nanodots. Higher thermal energy could provide the driving force for the phase transformation of GaN nanodots from zinc-blende to wurtzite structures. Metastable zinc-blende GaN nanodots can be synthesized by the surface modification of Si (111 by nitrogen plasma, i.e., the pre-nitridation treatment is done at a lower growth temperature. This is because the pre-nitridation process can provide a nitrogen-terminal surface for the following Ga droplet formation and a nitrogen-rich condition for the formation of GaN nanodots during droplet epitaxy. The pre-nitridation of Si substrates, the formation of a thin SiNx layer, could inhibit the phase transformation of GaN nanodots from zinc-blende to wurtzite phases. The pre-nitridation treatment also affects the dot size, density, and surface roughness of samples.

Experience of high-nitrogenous steel powder application in repairs and surface hardening of responsible parts for power equipment by plasma spraying

Science.gov (United States)

Kolpakov, A. S.; Kardonina, N. I.

2016-02-01

The questions of the application of novel diffusion-alloying high-nitrogenous steel powders for repair and surface hardening of responsible parts of power equipment by plasma spraying are considered. The appropriateness of the method for operative repair of equipment and increasing its service life is justified. General data on the structure, properties, and manufacture of nitrogen-, aluminum-, and chromium-containing steel powders that are economically alloyed using diffusion are described. It is noted that the nitrogen release during the decomposition of iron nitrides, when heating, protects the powder particles from oxidation in the plasma jet. It is shown that the coating retains 50% of nitrogen that is contained in the powder. Plasma spraying modes for diffusion-alloying high-nitrogenous steel powders are given. The service properties of plasma coatings based on these powders are analyzed. It is shown that the high-nitrogenous steel powders to a nitrogen content of 8.9 wt % provide the necessary wear resistance and hardness of the coating and the strength of its adhesion to the substrate and corrosion resistance to typical aggressive media. It is noted that increasing the coating porosity promotes stress relaxation and increases its thickness being limited with respect to delamination conditions in comparison with dense coatings on retention of the low defectiveness of the interface and high adhesion to the substrate. The examples of the application of high-nitrogenous steel powders in power engineering during equipment repairs by service companies and overhaul subdivisions of heat power plants are given. It is noted that the plasma spraying of diffusion-alloyed high-nitrogenous steel powders is a unique opportunity to restore nitrided steel products.

Intense pulsed heavy ion beam technology

International Nuclear Information System (INIS)

Masugata, Katsumi; Ito, Hiroaki

2010-01-01

Development of intense pulsed heavy ion beam accelerator technology is described for the application of materials processing. Gas puff plasma gun and vacuum arc discharge plasma gun were developed as an active ion source for magnetically insulated pulsed ion diode. Source plasma of nitrogen and aluminum were successfully produced with the gas puff plasma gun and the vacuum arc plasma gun, respectively. The ion diode was successfully operated with gas puff plasma gun at diode voltage 190 kV, diode current 2.2 kA and nitrogen ion beam of ion current density 27 A/cm 2 was obtained. The ion composition was evaluated by a Thomson parabola spectrometer and the purity of the nitrogen ion beam was estimated to be 86%. The diode also operated with aluminum ion source of vacuum arc plasma gun. The ion diode was operated at 200 kV, 12 kA, and aluminum ion beam of current density 230 A/cm 2 was obtained. The beam consists of aluminum ions (Al (1-3)+ ) of energy 60-400 keV, and protons (90-130 keV), and the purity was estimated to be 89%. The development of the bipolar pulse accelerator (BPA) was reported. A double coaxial type bipolar pulse generator was developed as the power supply of the BPA. The generator was tested with dummy load of 7.5 ohm, bipolar pulses of -138 kV, 72 ns (1st pulse) and +130 kV, 70 ns (2nd pulse) were successively generated. By applying the bipolar pulse to the drift tube of the BPA, nitrogen ion beam of 2 A/cm 2 was observed in the cathode, which suggests the bipolar pulse acceleration. (author)

Interaction of ultra-short ultra-intense laser pulses with under-dense plasmas

International Nuclear Information System (INIS)

Solodov, A.

2000-12-01

Different aspects of interaction of ultra-short ultra-intense laser pulses with underdense plasmas are studied analytically and numerically. These studies can be interesting for laser-driven electron acceleration in plasma, X-ray lasers, high-order harmonic generation, initial confinement fusion with fast ignition. For numerical simulations a fully-relativistic particle code WAKE was used, developed earlier at Ecole Polytechnique. It was modified during the work on the thesis in the part of simulation of ion motion, test electron motion, diagnostics for the field and plasma. The studies in the thesis cover the problems of photon acceleration in the plasma wake of a short intense laser pulse, phase velocity of the plasma wave in the Self-Modulated Laser Wake-Field Accelerator (SM LWFA), relativistic channeling of laser pulses with duration of the order of a plasma period, ion dynamics in the wake of a short intense laser pulse, plasma wave breaking. Simulation of three experiments on the laser pulse propagation in plasma and electron acceleration were performed. Among the main results of the thesis, it was found that reduction of the plasma wave phase velocity in the SM LWFA is crucial for electron acceleration, only if a plasma channel is used for the laser pulse guiding. Self-similar structures describing relativistic guiding of short laser pulses in plasmas were found and relativistic channeling of initially Gaussian laser pulses of a few plasma periods in duration was demonstrated. It was shown that ponderomotive force of a plasma wake excited by a short laser pulse forms a channel in plasma and plasma wave breaking in the channel was analyzed in detail. Effectiveness of electron acceleration by the laser field and plasma wave was compared and frequency shift of probe laser pulses by the plasma waves was found in conditions relevant to the current experiments. (author)

Atomic force microscopy of surface topography of nitrogen plasma treated steel

CERN Document Server

Mahboubi, F

2002-01-01

Nitriding of steels, using plasma environments has been practiced for many years. A lot of efforts have been put on developing new methods, such as plasma immersion ion implantation (Pl sup 3) and radio frequency (RF) plasma nitriding, for mass transfer of nitrogen into the surface of the work piece. This article presents the results obtained from an in depth investigation of the surface morphology of the treated samples, carried out using an atomic force microscope. Samples from a microalloyed steel, were treated by both methods for 5 hours at different temperatures ranging from 350 to 550 sup d eg sup C in 75% N sub 2 -25% H sub 2 atmosphere. It has been found that the surface of the samples treated by PI sup 3 technique, although having more favorable properties, were rougher than the surfaces treated by RF plasma nitriding.

High-Intensity High-order Harmonics Generated from Low-Density Plasma

International Nuclear Information System (INIS)

Ozaki, T.; Bom, L. B. Elouga; Abdul-Hadi, J.; Ganeev, R. A.; Haessler, S.; Salieres, P.

2009-01-01

We study the generation of high-order harmonics from lowly ionized plasma, using the 10 TW, 10 Hz laser of the Advanced Laser Light Source (ALLS). We perform detailed studies on the enhancement of a single order of the high-order harmonic spectrum generated in plasma using the fundamental and second harmonic of the ALLS beam line. We observe quasi-monochromatic harmonics for various targets, including Mn, Cr, Sn, and In. We identify most of the ionic/neutral transitions responsible for the enhancement, which all have strong oscillator strengths. We demonstrate intensity enhancements of the 13th, 17th, 29th, and 33rd harmonics from these targets using the 800 nm pump laser and varying its chirp. We also characterized the attosecond nature of such plasma harmonics, measuring attosecond pulse trains with 360 as duration for chromium plasma, using the technique of ''Reconstruction of Attosecond Beating by Interference of Two-photon Transitions''(RABBIT). These results show that plasma harmonics are intense source of ultrashort coherent soft x-rays.

Generation of radiation by intense plasma and electromagnetic undulators

International Nuclear Information System (INIS)

Joshi, C.

1989-01-01

This is a second year progress report which details the work on the generation of radiation by intense plasma and electromagnetic undulators being carried out at UCLA. The status of the experimental work is described and the future directions are outlined. We have completed the first phase of experiments on the plasma wiggler generation and characterization. Suitability of a null-pinch as a plasma source was investigated in great detail. It is found that a w of a few percent can be excited but there are trapped magnetic fields within null-pinch plasma which hinder the injection of the electrons. A new more uniform and field-free plasma source is now being characterized

Generation of radiation by intense plasma and electromagnetic undulators

International Nuclear Information System (INIS)

Joshi, C.

1989-01-01

This is a second year progress report which details the work on the generation of radiation by intense plasma and electromagnetic undulators being carried out at UCLA. The status of the experimental work is described and the future directions are outlined. We have completed the first phase of experiments on the plasma wiggler generation and characterization. Suitability of a θ-pinch as a plasma source was investigated in great detail. It is found that a w of a few percent can be excited but there are trapped magnetic fields within θ-pinch plasma which hinder the injection of the electrons. A few more uniform and field-free plasma source is now being characterized. 8 refs., 5 figs

Investigation of nitrogen atom production in Ar/N2 and He/N2 surface wave plasmas

International Nuclear Information System (INIS)

Tabbal, M.; Kazopoulo, M.; Christidis, T.; Isber, S.

2000-01-01

Full text: There is presently great interest in nitrogen plasmas for surface coating processes. Such as the deposition of nitride thin films and surface treatment of materials. Indeed, nitrogen plasmas have been used to nitride the surface of ferrous and non-ferrous materials in order to improve their surface properties such as resistance to corrosion and hardness. Moreover, the design and development of nitrogen atom sources could be essential for the synthesis of gallium nitride (GaN), a wide band-gap semiconductor whose properties have revolutionized the microelectronics and optoelectronics industries. Correlations have been established between the density of active species in the process, namely atomic nitrogen (N) produced by the discharge and GaN film properties. Thus, it is of fundamental importance to investigate the N-atom production mechanisms in such discharges. N-atom production has been studied in pure N 2 surface-wave plasmas (SWP), as a function of operating parameters, namely gas pressure and electrical power. These studies indicate that the increase in the gas temperature (T g ) limits the N-atom production. One possible way of enhancing the N 2 dissociation rate ([N]/[N 2 ]) in the plasma could be the use of gas mixtures such as Ar/N 2 or He/N 2 . the aim of this paper is to characterize an Ar/N 2 and He/N 2 surface-wave discharge (SWD) by optical emission spectroscopy (OES), in order to determine the optimal plasma conditions in terms of [N]/[N 2 ]. The plasma is generated by a radio frequency (40.68 MHz) wave launcher. The effect of mixing N 2 with Ar and He on the production of N-atoms in the plasma was investigated at varying experimental conditions, such as operating pressure (4.5 and 7.5 Torr), electrical power (40 to 120 W), at a total gas flow of 250 sccm. It was found that [N]/[N 2 ] increases with the partial pressure of Ar in the mixture by a factor of about 8 at 120W. Such an enhancement is reduced at lower incident powers. On the

21 CFR 862.1515 - Nitrogen (amino-nitrogen) test system.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Nitrogen (amino-nitrogen) test system. 862.1515... Systems § 862.1515 Nitrogen (amino-nitrogen) test system. (a) Identification. A nitrogen (amino-nitrogen) test system is a device intended to measure amino acid nitrogen levels in serum, plasma, and urine...

Depth distribution of nitrogen in silicon from plasma ion implantation

International Nuclear Information System (INIS)

Vajo, J.J.; Williams, J.D.; Wei, R.; Wilson, R.G.; Matossian, J.N.

1994-01-01

Plasma Ion Implantation (PII) is an ion implantation technique that eliminates the line-of-sight restriction of conventional ion-beam implantation and therefore allows for cost effective surface modification of large-scale objects or large-number of small-scale objects. In PII, a part to be implanted is immersed in a low-pressure (10 -4 --10 -5 Torr), partially-ionized plasma that surrounds the part with a plasma sheath. The part is negatively pulse biased up to 100 keV using a repetitive train (100--1,000 Hz) of short-duration (10--40 μsec) voltage pulses. The applied voltage develops across the sheath and accelerates plasma ions into the surface, implanting them omnidirectionally and simultaneously over the entire surface of the part. The depth distribution of the implanted ions influences the extent and type of surface modification achieved and depends upon many factors. These include three rise and fall time of the voltage-pulse waveform, the voltage-pulse amplitude, the ion specie, the ion density, and the temperature of the target. Understanding the contributions to the depth distribution from each of these factors will enable prediction of conditions that will be useful for implantation of large complex parts. To investigate the contributions to the measured depth distributions from these factors nitrogen, predominantly as N + 2 , has been implanted into silicon using PII at 50 and 100 keV (25 and 50 keV per N atom). The implanted depth distributions have been determined using secondary ion mass spectroscopy and Auger electron spectroscopy depth profiling. The distributions differ from the typical, approximately Gaussian, profiles that result from conventional mass selected monoenergetic ion beam implantation. In comparison with ion beam implants and numerical simulations the profiles appear ''filled-in'' with an approximately constant nitrogen concentration for depths less than the expected average ion range

Deposition and surface characterization of nanoparticles of zinc oxide using dense plasma focus device in nitrogen atmosphere

International Nuclear Information System (INIS)

Malhotra, Yashi; Srivastava, M P; Roy, Savita

2010-01-01

Nanoparticles of zinc oxide from zinc oxide pellets in the nitrogen plasma atmosphere are deposited on n and p type silicon substrates using Dense Plasma Focus device. The hot and dense nitrogen plasma formed during the focus phase ionizes the ZnO pellet, which then move upward in a fountain like shape and gets deposited on substrates which are placed above the top of the anode. Structural and surface properties of the deposited ZnO are investigated using X-ray diffraction and Atomic force microscope (AFM). X-ray spectra shows the diffraction plane (002) of ZnO nanoparticles deposited on Si with few shots in nitrogen atmosphere. AFM investigations revealed that there are nanoparticles of size between 15-80 nm on n-Si and p-Si substrates. The deposition on n-type Si is better than the p-type Si can be seen from AFM images, this may be due to different orientation of silicon.

CN emission spectroscopy study of carbon plasma in nitrogen environment

International Nuclear Information System (INIS)

Abdelli-Messaci, S.; Kerdja, T.; Bendib, A.; Malek, S.

2005-01-01

Spectroscopic emission diagnostics of a carbon plasma created by an excimer KrF laser pulse at three laser fluences (12, 25 and 32 J/cm 2 ) is performed under nitrogen ambient at pressures of 0.5 and 1 mbar. By following the time evolution of the radical CN spectral emission profiles, we notice, at a certain distance from the target surface, the existence of twin peaks for the time of flight distribution. This double structure depends on laser fluence and gas pressure parameters. The first peak moves forward in relation with the plasma expansion whereas the second peak moves backward and it is attributed to CN species undergoing oscillations or reflected shocks

Thermal equilibrium criteria in a nitrogen plasma

International Nuclear Information System (INIS)

Cilliers, W.A.; Hey, J.D.; Rash, J.P.S.

1975-01-01

A method for obtaining the lower electron density limit for LTE in a nitrogen plasma is described, whereby the experimentally determined ratio of the collisional-radiative ionization and recombination coefficients (S/α) is compared with the corresponding LTE value (Saha ratio). It is argued that if the electron density is increased from values of about 10 16 cm -3 , S/α should tend to the Saha ratio as LTE is approached For NII and NIII spectral lines, this is found to happen at an electron density of a few times 10 16 cm -3 when the electron temperature is about 3 eV, in good agreement with the LTE criterion of Griem. (author)

Tribological changes on SS304 stainless steel induced by nitrogen plasma immersion ion implantation with and without auxiliary heating

International Nuclear Information System (INIS)

Mello, C.B.; Ueda, M.; Lepienski, C.M.; Reuther, H.

2009-01-01

In order to achieve quite thick treated layers with reasonable thickness uniformity in SS304 steel, the plasma immersion ion implantation (PIII) process was run in high-temperature, up to 350 deg. C, to induce high thermal diffusion but avoid the white layer formation. In these experiments, we heated the sample-holder with a shielded resistive wire properly wound around it and subjected the SS samples to nitrogen glow discharge PIII with relatively low voltages (10 kV) in different temperatures. We also treated the SS samples by the traditional PIII method, slowly increasing the high voltage pulse intensities, until 14 kV at the end of processing, reaching temperatures of up to 350 deg. C. These modes of treatments were compared with respect to nitrogen implantation profiles, X-ray diffraction, tribology and mechanical properties. X-ray diffraction results indicated a much higher efficiency of auxiliary heated PIII mode compared to the ordinary PIII. Very prominent γ N peaks were observed for the first mode, indicating large concentration of nitrogen in thick layers, confirmed by the nitrogen profiles measured by GDOS and AES. Improved mechanical and tribological properties were obtained for SS304 samples treated by the PIII with auxiliary heating, more than for ordinary PIII. Hardness was enhanced by up to 2.77 times, as seen by nanoindentation tests.

Comparison of the behavior of fibroblast and bone marrow-derived mesenchymal stem cell on nitrogen plasma-treated gelatin films

International Nuclear Information System (INIS)

Prasertsung, I.; Kanokpanont, S.; Mongkolnavin, R.; Wong, C.S.; Panpranot, J.; Damrongsakkul, S.

2013-01-01

The attachment and growth behavior of mouse fibroblast (L929) and rat bone marrow-derived mesenchymal stem cell (MSC) on nitrogen plasma-treated and untreated gelatin films was investigated and compared. The gelatin films were prepared by solution casting (0.05% w/v) and crosslinked using dehydrothermal treatment. The crosslinked gelatin films were treated with nitrogen alternating current (AC) 50 Hz plasma systems at various treatment time. The results on the attachment and growth of two cells; L929 and MSC, on plasma-treated gelatin film showed that the number of attached and proliferated cells on plasma-treated gelatin films was significantly increased compared to untreated samples. However, no significant difference between the number of attached L929 and MSC on plasma-treated gelatin was observed. The shorter population doubling time and higher growth rate of cells cultured on plasma-treated film indicated the greater growth of cells, compared to ones on untreated films. The greatest enhancement of cell attachment and growth were noticed when the film was treated with nitrogen plasma for 9 to 15 s. This suggested that the greater attachment and growth of both cells on gelatin films resulted from the change of surface properties, i.e. hydrophilicity, surface energy, and chemistry. The suitable water contact angle and oxygen/nitrogen ratio (O/N) of gelatin film for best L929 and MSC attachment were observed at 27–32° and 1.4, respectively. These conditions also provided the best proliferation of cells on plasma-treated gelatin films. - Highlights: • We compared the attachment and growth behavior of L929 and MSC. • The attachment of two cells on plasma-treated gelatin was significantly increased. • The shorter population doubling time and higher growth rate of cells were observed. • L929 fibroblast exhibited the greater proliferation, compared to MSC

Spectroscopy of reactive species produced by low-energy atmospheric-pressure plasma on conductive target material surface

International Nuclear Information System (INIS)

Yamada, Hiromasa; Sakakita, Hajime; Kato, Susumu; Kim, Jaeho; Kiyama, Satoru; Fujiwara, Masanori; Itagaki, Hirotomo; Ikehara, Yuzuru; Okazaki, Toshiya; Ikehara, Sanae; Nakanishi, Hayao; Shimizu, Nobuyuki

2016-01-01

A method for blood coagulation using low-energy atmospheric-pressure plasma (LEAPP) is confirmed as an alternative procedure to reduce tissue damage caused by heat. Blood coagulation using LEAPP behaves differently depending on working gas species; helium is more effective than argon in promoting fast coagulation. To analyse the difference in reactive species produced by helium and argon plasma, spectroscopic measurements were conducted without and with a target material. To compare emissions, blood coagulation experiments using LEAPP for both plasmas were performed under almost identical conditions. Although many kinds of reactive species such as hydroxyl radicals and excited nitrogen molecules were observed with similar intensity in both plasmas, intensities of nitrogen ion molecules and nitric oxide molecules were extremely strong in the helium plasma. It is considered that nitrogen ion molecules were mainly produced by penning ionization by helium metastable. Near the target, a significant increase in the emissions of reactive species is observed. There is a possibility that electron acceleration was induced in a local electric field formed on the surface. However, in argon plasma, emissions from nitrogen ion were not measured even near the target surface. These differences between the two plasmas may be producing the difference in blood coagulation behaviour. To control the surrounding gas of the plasma, a gas-component-controllable chamber was assembled. Filling the chamber with O 2 /He or N 2 /He gas mixtures selectively produces either reactive oxygen species or reactive nitrogen species. Through selective treatments, this chamber would be useful in studying the effects of specific reactive species on blood coagulation. (paper)

Spectroscopy of reactive species produced by low-energy atmospheric-pressure plasma on conductive target material surface

Science.gov (United States)

Yamada, Hiromasa; Sakakita, Hajime; Kato, Susumu; Kim, Jaeho; Kiyama, Satoru; Fujiwara, Masanori; Itagaki, Hirotomo; Okazaki, Toshiya; Ikehara, Sanae; Nakanishi, Hayao; Shimizu, Nobuyuki; Ikehara, Yuzuru

2016-10-01

A method for blood coagulation using low-energy atmospheric-pressure plasma (LEAPP) is confirmed as an alternative procedure to reduce tissue damage caused by heat. Blood coagulation using LEAPP behaves differently depending on working gas species; helium is more effective than argon in promoting fast coagulation. To analyse the difference in reactive species produced by helium and argon plasma, spectroscopic measurements were conducted without and with a target material. To compare emissions, blood coagulation experiments using LEAPP for both plasmas were performed under almost identical conditions. Although many kinds of reactive species such as hydroxyl radicals and excited nitrogen molecules were observed with similar intensity in both plasmas, intensities of nitrogen ion molecules and nitric oxide molecules were extremely strong in the helium plasma. It is considered that nitrogen ion molecules were mainly produced by penning ionization by helium metastable. Near the target, a significant increase in the emissions of reactive species is observed. There is a possibility that electron acceleration was induced in a local electric field formed on the surface. However, in argon plasma, emissions from nitrogen ion were not measured even near the target surface. These differences between the two plasmas may be producing the difference in blood coagulation behaviour. To control the surrounding gas of the plasma, a gas-component-controllable chamber was assembled. Filling the chamber with O2/He or N2/He gas mixtures selectively produces either reactive oxygen species or reactive nitrogen species. Through selective treatments, this chamber would be useful in studying the effects of specific reactive species on blood coagulation.

DNA damage in oral cancer cells induced by nitrogen atmospheric pressure plasma jets

Energy Technology Data Exchange (ETDEWEB)

Han, Xu; Ptasinska, Sylwia [Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Department of Physics, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Klas, Matej [Radiation Laboratory, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Liu, Yueying [Harper Cancer Research Institute, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Sharon Stack, M. [Harper Cancer Research Institute, University of Notre Dame, Notre Dame, Indiana 46556 (United States); Department of Chemistry and Biochemistry, University of Notre Dame, Notre Dame, Indiana 46556 (United States)

2013-06-10

The nitrogen atmospheric pressure plasma jet (APPJ) was applied to induce DNA damage of SCC-25 oral cancer cells. Optical emission spectra were taken to characterize the reactive species produced in APPJ. In order to explore the spatial distribution of plasma effects, cells were placed onto photo-etched grid slides and the antibody H2A.X was used to locate double strand breaks of DNA inside nuclei using an immunofluorescence assay. The number of cells with double strand breaks in DNA was observed to be varied due to the distance from the irradiation center and duration of plasma treatment.

DNA damage in oral cancer cells induced by nitrogen atmospheric pressure plasma jets

International Nuclear Information System (INIS)

Han, Xu; Ptasinska, Sylwia; Klas, Matej; Liu, Yueying; Sharon Stack, M.

2013-01-01

The nitrogen atmospheric pressure plasma jet (APPJ) was applied to induce DNA damage of SCC-25 oral cancer cells. Optical emission spectra were taken to characterize the reactive species produced in APPJ. In order to explore the spatial distribution of plasma effects, cells were placed onto photo-etched grid slides and the antibody H2A.X was used to locate double strand breaks of DNA inside nuclei using an immunofluorescence assay. The number of cells with double strand breaks in DNA was observed to be varied due to the distance from the irradiation center and duration of plasma treatment.

Spectral line intensity irreversibility in circulatory plasma magnetization processes

Science.gov (United States)

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

2012-01-01

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

Self-modulation and anomalous collective scattering of laser produced intense ion beam in plasmas

Directory of Open Access Journals (Sweden)

K. Mima

2018-05-01

Full Text Available The collective interaction between intense ion beams and plasmas is studied by simulations and experiments, where an intense proton beam produced by a short pulse laser is injected into a pre-ionized gas. It is found that, depending on its current density, collective effects can significantly alter the propagated ion beam and the stopping power. The quantitative agreement that is found between theories and experiments constitutes the first validation of the collective interaction theory. The effects in the interaction between intense ion beams and background gas plasmas are of importance for the design of laser fusion reactors as well as for beam physics. Keywords: Two stream instabilities, Ultra intense short pulse laser, Proton beam, Wake field, Electron plasma wave, Laser plasma interaction, PACS codes: 52.38.Kd, 29.27.Fh, 52.40.Kh, 52.70.Nc

Investigation of intense XUV emission of nitrogen-puff Z-pinch with small energy input

International Nuclear Information System (INIS)

Raus, J.; Krejci, A.; Piffl, V.

1992-01-01

Light elements like nitrogen or carbon are suggested as optimum working media for small Z-pinches (several kJ energy input). It is shown that such elements can be ionized up to K-shell ionization stages not only in hot-spots, but also in the bulk plasma. The yield of nitrogen K-shell radiation (about 10 J/shot) is therefore substantially higher than that of the conventionally used neon. In addition to pinch physics and radiation dynamics, such radiation could be of interest for applications in the 'water window' spectral region. (author) 1 tab., 4 figs., 8 refs

Relativistic electron beam - plasma interaction with intense self-fields

International Nuclear Information System (INIS)

Davidson, R.C.

1984-01-01

The major interest in the equilibrium, stability and radiation properties of relativistic electron beams and in beam-plasma interactions originates from several diverse research areas. It is well known that a many-body collection of charged particles in which there is not overall charge neutrality and/or current neutrality can be characterized by intense self-electric fields and/or self-magnetic fields. Moreover, the intense equilibrium self-fields associated with the lack of charge neutrality and/or current neutrality can have a large effect on particle trajectories and on detailed equilibrium and stability behavior. The main emphasis in Sections 9.1.2-9.1.5 of this chapter is placed on investigations of the important influence of self-fields on the equilibrium and stability properties of magnetically confined electron beam-plasma systems. Atomic processes and discrete particle interactions (binary collisions) are omitted from the analysis, and collective processes are assumed to dominate on the time and length scales of interest. Moreover, both macroscopic (Section 9.1.2) and kinetic (Sections 9.1.3-9.1.5) theoretical models are developed and used to investigate equilibrium and stability properties in straight cylindrical geometry. Several of the classical waves and instabilities characteristic of nonneutral plasmas and beam-plasma systems are analyzed in Sections 9.1.2-9.1.5, including stable surface oscillation on a nonneutral electron beam, the ion resonance instability, the diocotron instability, two-stream instabilities between beam electrons and plasma electrons and between beam electrons and plasma ions, the filamentation instability, the modified two-stream instability, etc

Enhancing gas-phase reaction in a plasma using high intensity and high power ultrasonic acoustic waves

DEFF Research Database (Denmark)

2010-01-01

is absorbed into said plasma (104), and where a sound pressure level of said generated ultrasonic high intensity and high power acoustic waves (102) is at least substantially 140 dB and where an acoustic power of said generated ultrasonic high intensity and high power acoustic waves (102); is at least...... substantially 100 W. In this way, a high sound intensity and power are obtained that efficiently enhances a gas-phase reaction in the plasma, which enhances the plasma process, e.g. enabling more efficient ozone or hydrogen generation using plasma in relation to reaction speed and/or obtained concentration......This invention relates to enhancing a gas-phase reaction in a plasma comprising: creating plasma (104) by at least one plasma source (106), and wherein that the method further comprises: generating ultrasonic high intensity and high power acoustic waves (102) having a predetermined amount...

Time-resolved investigation of the surface chemical modification of poly(ethylene naphthalate) by nitrogen plasma treatment

International Nuclear Information System (INIS)

Grace, J.M.; Zhuang, H.K.; Gerenser, L.J.; Freeman, D.R.

2003-01-01

A low rf nitrogen plasma source was used to treat poly(ethylene-2, 6-naphthalate) web material. Nitrogen uptake, the N 1s centroid, the N 1s peak width, rearrangement of the ester (from the O 1s spectrum), and oxygen level were measured using x-ray photoelectron spectroscopy as a function of treatment time at several treatment conditions. The observed changes in surface chemistry with treatment time are roughly consistent with a dose response having a linear regime at low doses and a saturation regime at high doses (where dose is power/width/web speed). Hence, to a first approximation, the flux densities (to the web) of relevant species scale with power. As the dose increases, the distribution of nitrogen groups formed broadens and shifts toward higher N 1s binding energy, suggesting that a larger fraction of the nitrogen-containing species are amines at low doses and amides at higher doses. The breadth of the distribution of nitrogen-containing species appears to be strongly correlated with the amount of nitrogen incorporated in the PEN surface. A surface sites model was applied to the measured nitrogen uptake as a function of treatment time. Phenomenological nitrogen incorporation and loss terms were determined in the context of this model. Both terms increase with treatment power and treatment pressure. The ratio, however, varies to a much smaller degree as a function of process conditions, with high powers and pressures giving the highest ratio. Further elucidation of the incorporation and loss processes should be possible with plasma diagnostic data related to species concentrations

Topics in high-intensity laser plasma interaction

International Nuclear Information System (INIS)

Leemans, W.P.

1991-01-01

The interaction of high intensity laser pulses with pre-formed and laser-produced plasmas is studied. Through experiments and simulations we have investigated stimulated Compton scattering in preformed plasmas and the plasma physics aspects of tunnel-ionized gases. A theoretical study is presented on the nonlinear dynamics of relativistic plasma waves driven by colinear optical mixing. The electron density-fluctuation spectra induced by stimulated Compton scattering have been directly observed for the first time. A CO2 laser was focused into pre-formed plasmas with densities n(e) varied from 0.4-6 x 10(exp 16) cu cm. The fluctuations corresponding to backscatter were probed using Thomson scattering. At low n(e), the scattered spectra peak at a frequency shift Delta omega is approximately kv e and appears to be in a linear regime. At the highest n(e), a nonlinear saturation of the SCS instability is observed due to a self-induced perturbation of the electron distribution function. Tunnel-ionized plasmas have been studied through experiments and particle simulations. Experimentally, qualitative evidence for plasma temperature control by varying the laser polarization was obtained by the measurement of stimulated Compton scattering fluctuation spectra and x-ray emission from such plasmas. A higher parallel temperature than expected from the single-particle tunneling model was observed. Simulations indicate that stochastic heating and the Weibel instability play an important role in plasma heating in all directions and isotropization. The non-linear dynamics associated with beatwave (Delta omega, Delta k) excited long wavelength plasma waves in the presence of strong, short wavelength density ripple have been examined, using the relativistic Lagrangian oscillator model. This model shows period doubling that roughly follows Feigenbaum scaling, and a transition to chaos

A High-Intensity, RF Plasma-Sputter Negative Ion Source

International Nuclear Information System (INIS)

Alton, G.D.; Bao, Y.; Cui, B.; Lohwasser, R.; Reed, C.A.; Zhang, T.

1999-01-01

A high-intensity, plasma-sputter negative-ion source based on the use of RF power for plasma generation has been developed that can be operated in either pulsed or dc modes. The source utilizes a high-Q, self-igniting, inductively coupled antenna system, operating at 80 MHz that has been optimized to generate Cs-seeded plasmas at low pressures (typically, - (610 microA); F - (100 microA); Si - (500 microA); S - (500 microA); P - (125 microA); Cl - (200 microA); Ni - (150 microA); Cu - (230 microA); Ge - (125 microA); As - (100 microA); Se - (200 microA); Ag - (70 microA); Pt - (125 microA); Au - (250 microA). The normalized emittance var e psilon n of the source at the 80% contour is: var e psilon n = 7.5 mm.mrad.(MeV) 1/2 . The design principles of the source, operational parameters, ion optics, emittance and intensities for a number of negative-ion species will be presented in this report

Comparison of plasma generated nitrogen fertilizer to conventional fertilizers ammonium nitrate and sodium nitrate for pre-emergent and seedling growth

Science.gov (United States)

Andhavarapu, A.; King, W.; Lindsay, A.; Byrns, B.; Knappe, D.; Fonteno, W.; Shannon, S.

2014-10-01

Plasma source generated nitrogen fertilizer is compared to conventional nitrogen fertilizers in water for plant growth. Root, shoot sizes, and weights are used to examine differences between plant treatment groups. With a simple coaxial structure creating a large-volume atmospheric glow discharge, a 162 MHz generator drives the air plasma. The VHF plasma source emits a steady state glow; the high drive frequency is believed to inhibit the glow-to-arc transition for non-thermal discharge generation. To create the plasma activated water (PAW) solutions used for plant treatment, the discharge is held over distilled water until a 100 ppm nitrate aqueous concentration is achieved. The discharge is used to incorporate nitrogen species into aqueous solution, which is used to fertilize radishes, marigolds, and tomatoes. In a four week experiment, these plants are watered with four different solutions: tap water, dissolved ammonium nitrate DI water, dissolved sodium nitrate DI water, and PAW. Ammonium nitrate solution has the same amount of total nitrogen as PAW; sodium nitrate solution has the same amount of nitrate as PAW. T-tests are used to determine statistical significance in plant group growth differences. PAW fertilization chemical mechanisms are presented.

Plasma-assisted nitrogen doping of VACNTs for efficiently enhancing the supercapacitor performance

Energy Technology Data Exchange (ETDEWEB)

Mashayekhi, Alireza; Hosseini, Seyed Mahmoud [University of Tehran, Nano-fabricated Energy Devices Laboratory, School of Electrical and Computer Engineering, College of Engineering (Iran, Islamic Republic of); Hassanpour Amiri, Morteza; Namdar, Naser [University of Tehran, Thin Film and Nano-electronics Laboratory, Nano-electronics Centre of Excellence, School of Electrical and Computer Engineering, College of Engineering (Iran, Islamic Republic of); Sanaee, Zeinab, E-mail: z.sanaee@ut.ac.ir [University of Tehran, Nano-fabricated Energy Devices Laboratory, School of Electrical and Computer Engineering, College of Engineering (Iran, Islamic Republic of)

2016-06-15

Nitrogen doping of vertically aligned carbon nanotubes (VACNTs) using plasma-enhanced chemical vapour deposition has been investigated to improve the supercapacitance performance of CNTs. Incorporating electrochemical measurements on the open-ended nitrogen-doped CNTs, showed the achievement of 6 times improvement in the capacitance value. For nitrogen-doped CNTs on silicon substrate, specific capacitance of 60 F g{sup −1} was obtained in 0.5 M KCl solution, with capacity retention ratio above 90 % after cycled at 0.1 A g{sup −1} for 5000 cycles. Using this sample, a symmetric supercapacitance was fabricated which showed the power density of 37.5 kW kg{sup −1}. The facile fabrication approach and its excellent capacitance improvement, propose it as an efficient technique for enhancing the supercapacitance performance of the carbon-based electrodes.

Density dependence of line intensities and application to plasma diagnostics

International Nuclear Information System (INIS)

Masai, Kuniaki.

1993-02-01

Electron density dependence of spectral lines are discussed in view of application to density diagnostics of plasmas. The dependence arises from competitive level population processes, radiative and collisional transitions from the excited states. Results of the measurement on tokamak plasmas are presented to demonstrate the usefulness of line intensity ratios for density diagnostics. Also general characteristics related to density dependence are discussed with atomic-number scaling for H-like and He-like systems to be helpful for application to higher density plasmas. (author)

Electron Parametric Instabilities Driven by Relativistically Intense Laser Light in Plasma

Science.gov (United States)

Barr, H. C.; Mason, P.; Parr, D. M.

1999-08-01

A unified treatment of electron parametric instabilities driven by ultraintense laser light in plasma is described. It is valid for any intensity, polarization, plasma density, and scattering geometry. The method is applied to linearly polarized light in both underdense plasma and overdense plasma accessible by self-induced transparency. New options arise which are hybrids of stimulated Raman scattering, the two plasmon decay, the relativistic modulational and filamentation instabilities, and stimulated harmonic generation. There is vigorous growth over a wide range of wave numbers and harmonics.

Images of Complex Interactions of an Intense Ion Beam with Plasma Electrons

International Nuclear Information System (INIS)

Kaganovich, Igor D.; Startsev, Edward; Davidson, Ronald C.

2004-01-01

Ion beam propagation in a background plasma is an important scientific issue for many practical applications. The process of ion beam charge and current neutralization is complex because plasma electrons move in strong electric and magnetic fields of the beam. Computer simulation images of plasma interaction with an intense ion beam pulse are presented

Weibel instability mediated collisionless shocks using intense laser-driven plasmas

Science.gov (United States)

Palaniyappan, Sasikumar; Fiuza, Federico; Huang, Chengkun; Gautier, Donald; Ma, Wenjun; Schreiber, Jorg; Raymer, Abel; Fernandez, Juan; Shimada, Tom; Johnson, Randall

2017-10-01

The origin of cosmic rays remains a long-standing challenge in astrophysics and continues to fascinate physicists. It is believed that ``collisionless shocks'' - where the particle Coulomb mean free path is much larger that the shock transition - are a dominant source of energetic cosmic rays. These shocks are ubiquitous in astrophysical environments such as gamma-ray bursts, supernova remnants, pulsar wind nebula and coronal mass ejections from the sun. A particular type of electromagnetic plasma instability known as Weibel instability is believed to be the dominant mechanism behind the formation of these collisionless shocks in the cosmos. The understanding of the microphysics behind collisionless shocks and their particle acceleration is tightly related with nonlinear basic plasma processes and remains a grand challenge. In this poster, we will present results from recent experiments at the LANL Trident laser facility studying collisionless shocks using intense ps laser (80J, 650 fs - peak intensity of 1020 W/cm2) driven near-critical plasmas using carbon nanotube foam targets. A second short pulse laser driven protons from few microns thick gold foil is used to radiograph the main laser-driven plasma. Work supported by the LDRD program at LANL.

The interaction of intense subpicosecond laser pulses with underdense plasmas

Energy Technology Data Exchange (ETDEWEB)

Coverdale, Christine Ann [Univ. of California, Davis, CA (United States)

1995-05-11

Laser-plasma interactions have been of interest for many years not only from a basic physics standpoint, but also for their relevance to numerous applications. Advances in laser technology in recent years have resulted in compact laser systems capable of generating (psec), 10¹⁶ W/cm² laser pulses. These lasers have provided a new regime in which to study laser-plasma interactions, a regime characterized by L_plasma ≥ 2L_Rayleigh > cτ. The goal of this dissertation is to experimentally characterize the interaction of a short pulse, high intensity laser with an underdense plasma (n_o ≤ 0.05n_cr). Specifically, the parametric instability known as stimulated Raman scatter (SRS) is investigated to determine its behavior when driven by a short, intense laser pulse. Both the forward Raman scatter instability and backscattered Raman instability are studied. The coupled partial differential equations which describe the growth of SRS are reviewed and solved for typical experimental laser and plasma parameters. This solution shows the growth of the waves (electron plasma and scattered light) generated via stimulated Raman scatter. The dispersion relation is also derived and solved for experimentally accessible parameters. The solution of the dispersion relation is used to predict where (in k-space) and at what frequency (in ω-space) the instability will grow. Both the nonrelativistic and relativistic regimes of the instability are considered.

Structure and photoluminescence of boron and nitrogen co-doped carbon nanorods

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); Gao, B. [College of Computer Science, Chongqing University, Chongqing 400044 (China); Chongqing Municipal Education Examinations Authority, Chongqing 401147 (China); Zhong, X.X., E-mail: xxzhong@sjtu.edu.cn [Department of Physics and Astronomy, Shanghai Jiao Tong University, Shanghai 200240 (China); Shao, R.W.; Zheng, K. [Institute of Microstructure and Properties of Advanced Materials, Beijing University of Technology, Beijing 100124 (China)

2016-07-15

Graphical abstract: Boron- and nitrogen- doped carbon nanorods. - Highlights: • The co-doping of nitrogen and boron in carbon nanorods. • The doping mechanism of nitrogen and boron in carbon nanorods by plasma. • Photoluminescence properties of nitrogen- and boron-doped carbon nanorods. - Abstract: Boron and nitrogen doped carbon nanorods (BNCNRs) were synthesized by plasma-enhanced hot filament chemical vapor deposition, where methane, nitrogen and hydrogen were used as the reaction gases and boron carbide was the boron source. The results of scanning electron microscopy, micro-Raman spectroscopy, transmission electron microscopy and X-ray photoelectron spectroscopy indicate that boron and nitrogen can be used as co-dopants in amorphous carbon nanorods. Combined with the characterization results, the doping mechanism was studied. The mechanism is used to explain the formation of different carbon materials by different methods. The photoluminescence (PL) properties of BNCNRs were studied. The PL results show that the BNCNRs generate strong green PL bands and weak blue PL bands, and the PL intensity lowered due to the doping of boron. The outcomes advance our knowledge on the synthesis and optical properties of carbon-based nanomaterials and contribute to the development of optoelectronic nanodevices based on nano-carbon mateirals.

Self-resonant wakefield excitation by intense laser pulse in plasmas

International Nuclear Information System (INIS)

Andreev, N.E.; Pogosova, A.A.; Gorbunov, L.M.; Ramazashvili, R.R.; Kirsanov, V.I.

1993-01-01

It is demonstrated by theoretical analysis and numerical calculations that in an underdense plasma the process of three-dimensional evolution of the short and strong laser pulse (with duration equal to several plasma periods) leads to compression and self-modulation of the pulse, so that during a fairly long period of time beats of pulse amplitude generates resonantly a strong and stable plasma wakefield. The intensity of the wake-field is so high that it can provide a new promising outlook for the plasma based accelerator concept. Linear analysis of dispersion relation predicts that taking into account transverse component of wavenumber considerably increases the growth rate of resonance instability of the pulse. The numerical simulations demonstrate that considered self-focusing and resonant-modulation instability are essentially three dimensional processes. Laser field evolution in each transverse cross section of the pulse is synchronized by the regular structure of plasma wave that is excited by the pulse. The considered effect of resonant modulation has a threshold. For the pulses with the intensity below the threshold the refraction dominates and no modulation appears. The studied phenomenon can be referred to as the Self-Resonant Wakefield (SRWF) excitation that is driven by self-focusing and self-modulation of laser pulse with quite a moderate initial duration. In fact, this method of excitation differs from both suggested in Ref.1 (PBWA) and in Refs.2,3 (LWFA), being even more than the combination of these concepts. Unlike the first scheme it does not require initially the two-frequency laser pulse, since the modulation here appears in the most natural way due to evolution of the pulse. In contrast with the LWFA, the considered SRWF generation scheme gives the possibility to raise the intensity of wake-excitation due to pulse self-focusing ( initial stage) and self modulation (second stage)

Intensity and shape of spectral lines from laser-produced plasmas

Energy Technology Data Exchange (ETDEWEB)

Jamelot, G; Jaegle, P; Carillon, A; Wehenkel, C [Centre National de la Recherche Scientifique, 91 - Orsay (France); Paris-11 Univ., 91 - Orsay (France); Ecole Polytechnique, 91 - Palaiseau (France))

1979-01-01

In starting from spectral studies of multicharged ions in dense laser-produced plasmas, the main processes which determine the intensity and the shape of lines in the X-UV range are described. The role of radiation transfer is underlined. Intensity anomalies resulting from occurrence of population inversions are considered and a recent experiment performed for investigating such anomalies is described.

Density and potential measurements in an intense ion-beam-generated plasma

International Nuclear Information System (INIS)

Abt, N.E.

1982-05-01

Neutral beams are created by intense large area ion beams which are neutralized in a gas cell. The interaction of the beam with the gas cell creates a plasma. Such a plasma is studied here. The basic plasma parameters, electron temperature, density, and plasma potential, are measured as a function of beam current and neutral gas pressure. These measurements are compared to a model based on the solution of Poisson's equation. Because of the cylindrical geometry the equation cannot be solved analytically. Details of the numerical method are presented

Interaction of dense nitrogen plasma with SS304 surface using APF plasma focus device

Science.gov (United States)

Afrashteh, M.; Habibi, M.; Heydari, E.

2012-04-01

The nitridation of SS304 surfaces is obtained by irradiating nitrogen ions from Amirkabir plasma focus device, which use multiple focus deposition shots at optimum distance 10 cm from the anode. The Vickers Micro-Hardness values are improved more than twice for the nitrided samples comparing to the nonnitrided ones. The X-ray diffraction (XRD) analysis is carried out in order to explore the phase changes in the near surface structure of the metals. The results of Scanning Electron Microscopy (SEM) indicate changes in surface morphology which are the emergence of smooth and uniform film on the surface of the nitrided metals.

EPDM Rubber Modified by Nitrogen Plasma Immersion Ion Implantation.

Science.gov (United States)

Kondyurin, Alexey

2018-04-24

Ethylene-propylene diene monomer rubber (EPDM) was treated by plasma immersion ion implantation (PIII) with nitrogen ions of 20 keV energy and fluence from 10 13 to 10 16 ions/cm². The Fourier-transform infrared attenuated total reflection spectra, atomic force microscopy and optical microscopy showed significant structure changes of the surface. The analysis of an interface of PIII treated EPDM rubber with polyurethane binder showed a cohesive character of the adhesion joint fracture at the presence of solvent and interpreted as covalent bond network formation between the PIII treated rubber and the adhesive.

EPDM Rubber Modified by Nitrogen Plasma Immersion Ion Implantation

Directory of Open Access Journals (Sweden)

Alexey Kondyurin

2018-04-01

Full Text Available Ethylene-propylene diene monomer rubber (EPDM was treated by plasma immersion ion implantation (PIII with nitrogen ions of 20 keV energy and fluence from 1013 to 1016 ions/cm2. The Fourier-transform infrared attenuated total reflection spectra, atomic force microscopy and optical microscopy showed significant structure changes of the surface. The analysis of an interface of PIII treated EPDM rubber with polyurethane binder showed a cohesive character of the adhesion joint fracture at the presence of solvent and interpreted as covalent bond network formation between the PIII treated rubber and the adhesive.

Simulation of intense short-pulse laser-plasma interaction

International Nuclear Information System (INIS)

Yamagiwa, Mitsuru

2000-01-01

We have completed the massive parallelization of a 2-dimensional giga-particle code and have achieved a 530-fold acceleration rate with 512 processing elements (PE's). Using this we have implemented a simulation of the interaction of a solid thin film and a high intensity laser and have discovered a phenomenon in which high quality short pulses from the far ultraviolet to soft X-rays are generated at the back surface of the thin layer. We have also introduced the atomic process database code (Hullac) and have the possibility for high precision simulations of X-ray laser radiation. With respect to laser acceleration we have the possibility to quantitatively evaluate relativistic self-focusing assumed to occur in higher intensity fields. Ion acceleration from a solid target and an underdense plasma irradiated by an intense and an ultra intense laser, respectively, has also been studied by particle-in-cell (PIC) simulations. (author)

DNA damage in oral cancer and normal cells induced by nitrogen atmospheric pressure plasma jets

Science.gov (United States)

Han, Xu; Kapaldo, James; Liu, Yueying; Stack, M. Sharon; Ptasinska, Sylwia

2015-09-01

Nitrogen atmospheric pressure plasma jets (APPJs) have been shown to effectively induce DNA double strand breaks in SCC25 oral cancer cells. The APPJ source constructed in our laboratory operates based on dielectric barrier discharge. It consists of two copper electrodes alternatively wrapping around a fused silica tube with nitrogen as a feed gas. It is generally more challenging to ignite plasma in N2 atmosphere than in noble gases. However, N2 provides additional advantages such as lower costs compared to noble gases, thus this design can be beneficial for the future long-term clinical use. To compare the effects of plasma on cancer cells (SCC25) and normal cells (OKF), the cells from both types were treated at the same experimental condition for various treatment times. The effective area with different damage levels after the treatment was visualized as 3D maps. The delayed damage effects were also explored by varying the incubation times after the treatment. All of these studies are critical for a better understanding of the damage responses of cellular systems exposed to the plasma radiation, thus are useful for the development of the advanced plasma cancer therapy. The research described herein was supported by the Division of Chemical Sciences, Geosciences and Biosciences, Basic Energy Sciences, Office of Science, United States Department of Energy through Grant No. DE-FC02-04ER15533.

Effect of low-damage inductively coupled plasma on shallow nitrogen-vacancy centers in diamond

Energy Technology Data Exchange (ETDEWEB)

Fávaro de Oliveira, Felipe; Momenzadeh, S. Ali; Wang, Ya; Denisenko, Andrej, E-mail: a.denisenko@physik.uni-stuttgart.de [3. Institute of Physics, Research Center SCoPE and IQST, University of Stuttgart, 70569 Stuttgart (Germany); Konuma, Mitsuharu [Max Planck Institute for Solid State Research, 70569 Stuttgart (Germany); Markham, Matthew; Edmonds, Andrew M. [Element Six Innovation, Harwell Oxford, Didcot, Oxfordshire OX11 0QR (United Kingdom); Wrachtrup, Jörg [3. Institute of Physics, Research Center SCoPE and IQST, University of Stuttgart, 70569 Stuttgart (Germany); Max Planck Institute for Solid State Research, 70569 Stuttgart (Germany)

2015-08-17

Near-surface nitrogen-vacancy (NV) centers in diamond have been successfully employed as atomic-sized magnetic field sensors for external spins over the last years. A key challenge is still to develop a method to bring NV centers at nanometer proximity to the diamond surface while preserving their optical and spin properties. To that aim we present a method of controlled diamond etching with nanometric precision using an oxygen inductively coupled plasma process. Importantly, no traces of plasma-induced damages to the etched surface could be detected by X-ray photoelectron spectroscopy and confocal photoluminescence microscopy techniques. In addition, by profiling the depth of NV centers created by 5.0 keV of nitrogen implantation energy, no plasma-induced quenching in their fluorescence could be observed. Moreover, the developed etching process allowed even the channeling tail in their depth distribution to be resolved. Furthermore, treating a {sup 12}C isotopically purified diamond revealed a threefold increase in T{sub 2} times for NV centers with <4 nm of depth (measured by nuclear magnetic resonance signal from protons at the diamond surface) in comparison to the initial oxygen-terminated surface.

Structural and tribological properties of carbon steels modified by plasma pulses

International Nuclear Information System (INIS)

Sartowska, B.; Walis, L.; Piekoszewski, J.; Senatorski, J.; Stanislawski, J.; Nowicki, L.; Ratajczak, R.; Barlak, M.; Kopcewicz, M.; Kalinowska, J.; Prokert, F.

2006-01-01

Carbon steels with different concentration of carbon and heat (Armco-iron, steels 20, 45, 65 and N9) were treated according to the standard procedures: they were irradiated with five intense (about 5 J/cm 2 ), short (μs range) argon or nitrogen plasma pulses generated in a rod plasma injector (RPI) type of plasma generator. Samples were characterized by the following methods: nuclear reaction analysis (NRA) 14 N(d,α) 12 C , scanning electron microscopy (SEM), conversion electron Moessbauer spectroscopy (CEMS), X-ray diffraction analysis (GXRD), and Amsler wear tests. SEM observations shown that the morphology of the pulse treated samples, both argon and nitrogen plasma are identical. It has been found, that nitrogen is much more efficient than argon in ausenitization of carbon steel. The craters and droplets are uniformly distributed over the surface, which is typical of melted and rapidly recrystallized top layers. The thickness of the modified layers is in the range of 1.2-1.6 μm

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.

Growth and content of Spirulina platensis biomass chlorophyll cultivated at different values of light intensity and temperature using different nitrogen sources

Directory of Open Access Journals (Sweden)

Eliane Dalva Godoy Danesi

2011-03-01

Full Text Available The effects of light intensity and temperature in S. platensis cultivation with potassium nitrate or urea as nitrogen source were investigated, as well as the biomass chlorophyll contents of this cyanobacteria, through the Response Surface Methodology. Experiments were performed at temperatures from 25 to 34.5ºC and light intensities from 15 to 69 µmol photons m-2 s-1, in mineral medium. In cultivations with both sources of nitrogen, KNO3 and urea, statistic evaluation through multiple regression, no interactions of such independent variables were detected in the results of the dependent variables maximum cell concentration, chlorophyll biomass contents, cell and chlorophyll productivities, as well as in the nitrogen-cell conversion factor. In cultivation performed with both sources of nitrogen, it was possible to obtain satisfactory adjustments to relate the dependent variables to the independent variables. The best results were achieved at temperature of 30ºC, at light intensity of 60 µmol photons m-2s-1, for cell growth, with cell productivity of approximately 95 mg L-1 d-1 in cultivations with urea. For the chlorophyll biomass content, the most adequate light intensity was 24 µmol photons m-2 s-1.

Producing High Intense Attosecond Pulse Train by Interaction of Three-Color Pulse and Overdense Plasma

Science.gov (United States)

Salehi, M.; Mirzanejad, S.

2017-05-01

Amplifying the attosecond pulse by the chirp pulse amplification method is impossible. Furthermore, the intensity of attosecond pulse is low in the interaction of laser pulse and underdense plasma. This motivates us to propose using a multi-color pulse to produce the high intense attosecond pulse. In the present study, the relativistic interaction of a three-color linearly-polarized laser-pulse with highly overdense plasma is studied. We show that the combination of {{ω }}1, {{ω }}2 and {{ω }}3 frequencies decreases the instance full width at half maximum reflected attosecond pulse train from the overdense plasma surface. Moreover, we show that the three-color pulse increases the intensity of generated harmonics, which is explained by the relativistic oscillating mirror model. The obtained results demonstrate that if the three-color laser pulse interacts with overdense plasma, it will enhance two orders of magnitude of intensity of ultra short attosecond pulses in comparison with monochromatic pulse.

Analytical calculations of intense Gaussian laser beam propagating in plasmas with relativistic collision correction

International Nuclear Information System (INIS)

Wang Ying; Yuan Chengxun; Gao Ruilin; Zhou Zhongxiang

2012-01-01

Theoretical investigations of a Gaussian laser beam propagating in relativistic plasmas have been performed with the WKB method and complex eikonal function. We consider the relativistic nonlinearity induced by intense laser beam, and present the relativistically generalized forms of the plasma frequency and electron collision frequency in plasmas. The coupled differential equations describing the propagation variations of laser beam are derived and numerically solved. The obtained simulation results present the similar variation tendency with experiments. By changing the plasma density, we theoretically analyze the feasibility of using a plasmas slab of a fixed thickness to compress the laser beam-width and acquire the focused laser intensity. The present work complements the relativistic correction of the electron collision frequency with reasonable derivations, promotes the theoretical approaching to experiments and provides effective instructions to the practical laser-plasma interactions.

Ammonia formation and W coatings interaction with deuterium/nitrogen plasmas in the linear device GyM

Energy Technology Data Exchange (ETDEWEB)

Laguardia, L., E-mail: laguardia@ifp.cnr.it [CNR, Istituto di Fisica del Plasma“P. Caldirola”, Milan (Italy); Caniello, R.; Cremona, A. [CNR, Istituto di Fisica del Plasma“P. Caldirola”, Milan (Italy); Dellasega, D. [CNR, Istituto di Fisica del Plasma“P. Caldirola”, Milan (Italy); Politecnico di Milano, Dipartimento di Energia, Milan (Italy); Dell’Era, F.; Ghezzi, F.; Gittini, G.; Granucci, G.; Mellera, V.; Minelli, D.; Pallotta, F. [CNR, Istituto di Fisica del Plasma“P. Caldirola”, Milan (Italy); Passoni, M. [CNR, Istituto di Fisica del Plasma“P. Caldirola”, Milan (Italy); Politecnico di Milano, Dipartimento di Energia, Milan (Italy); Ricci, D.; Vassallo, E. [CNR, Istituto di Fisica del Plasma“P. Caldirola”, Milan (Italy)

2015-08-15

In this work results of the first D{sub 2}/N{sub 2} experiments in GyM, a linear device able to produce plasmas of interest for the ITER divertor (n{sub e} 5 ⋅ 10{sup 10} cm{sup −3}, Te 5 eV, ion flux 3–5 ⋅ 10{sup 20} m{sup −2}s{sup −1}) are presented. Plasmas simulating a N-seeding scenario have been performed to evaluate ammonia formation and its effect on exposed W coatings. The presence of ND emission lines in the plasma can be correlated with the formation of ammonia, further directly detected and quantified by chromatography analysis of the exhaust. Four different W specimens were exposed in GyM to a plasma fluence of 8.78 ⋅ 10{sup 23} m{sup −2}. XPS analysis evidenced the formation of W{sub x}N{sub y} layers with nitrogen concentration in the range of 1–10% depending on the initial morphology and structure of the W samples. In all analyzed cases, nitrogen was bound and retained within the first 6 nm below the surface and no further diffusion of N into the bulk was observed.

Occurrence of Equatorial Plasma Bubbles during Intense Magnetic Storms

Directory of Open Access Journals (Sweden)

Chao-Song Huang

2011-01-01

Full Text Available An important issue in low-latitude ionospheric space weather is how magnetic storms affect the generation of equatorial plasma bubbles. In this study, we present the measurements of the ion density and velocity in the evening equatorial ionosphere by the Defense Meteorological Satellite Program (DMSP satellites during 22 intense magnetic storms. The DMSP measurements show that deep ion density depletions (plasma bubbles are generated after the interplanetary magnetic field (IMF turns southward. The time delay between the IMF southward turning and the first DMSP detection of plasma depletions decreases with the minimum value of the IMF Bz, the maximum value of the interplanetary electric field (IEF Ey, and the magnitude of the Dst index. The results of this study provide strong evidence that penetration electric field associated with southward IMF during the main phase of magnetic storms increases the generation of equatorial plasma bubbles in the evening sector.

Reduction of nitrogen oxides from simulated exhaust gas by using plasma-catalytic process

International Nuclear Information System (INIS)

Mok, Young Sun; Koh, Dong Jun; Shin, Dong Nam; Kim, Kyong Tae

2004-01-01

Removal of nitrogen oxides (NO x ) using a nonthermal plasma reactor (dielectric-packed bed reactor) combined with monolith V 2 O 5 /TiO 2 catalyst was investigated. The effect of initial NO x concentration, feed gas flow rate (space velocity), humidity, and reaction temperature on the removal of NO x was examined. The plasma reactor used can be energized by either ac or pulse voltage. An attempt was made to utilize the electrical ignition system of an internal combustion engine as a high-voltage pulse generator for the plasma reactor. When the plasma reactor was energized by the electrical ignition system, NO was readily oxidized to NO 2 . Performance was as good as with ac energization. Increasing the fraction of NO 2 in NO x , which is the main role of the plasma reactor, largely enhanced the NO x removal efficiency. In the plasma-catalytic reactor, the increases in initial NO x concentration, space velocity (feed gas flow rate) and humidity lowered the NO x removal efficiency. However, the reaction temperature in the range up to 473 K did not significantly affect the NO x removal efficiency in the presence of plasma discharge

Liquid Phase Plasma Synthesis of Iron Oxide Nanoparticles on Nitrogen-Doped Activated Carbon Resulting in Nanocomposite for Supercapacitor Applications.

Science.gov (United States)

Lee, Heon; Lee, Won-June; Park, Young-Kwon; Ki, Seo Jin; Kim, Byung-Joo; Jung, Sang-Chul

2018-03-25

Iron oxide nanoparticles supported on nitrogen-doped activated carbon powder were synthesized using an innovative plasma-in-liquid method, called the liquid phase plasma (LPP) method. Nitrogen-doped carbon (NC) was prepared by a primary LPP reaction using an ammonium chloride reactant solution, and an iron oxide/NC composite (IONCC) was prepared by a secondary LPP reaction using an iron chloride reactant solution. The nitrogen component at 3.77 at. % formed uniformly over the activated carbon (AC) surface after a 1 h LPP reaction. Iron oxide nanoparticles, 40~100 nm in size, were impregnated homogeneously over the NC surface after the LPP reaction, and were identified as Fe₃O₄ by X-ray photoelectron spectroscopy and X-ray diffraction. NC and IONCCs exhibited pseudo-capacitive characteristics, and their specific capacitance and cycling stability were superior to those of bare AC. The nitrogen content on the NC surface increased the compatibility and charge transfer rate, and the composites containing iron oxide exhibited a lower equivalent series resistance.

Study of a recombination X-ray laser scheme in a H-like nitrogen plasma created by optical field induced ionization; Etude de la faisabilite d'un laser X en recombinaison dans un plasma d'azote hydrogenoide cree par effet tunnel

Energy Technology Data Exchange (ETDEWEB)

Hulin, S

2001-07-01

Thanks to their high brightness and short wavelength, X ray lasers are interesting diagnostics in many experiments because they can efficiently probe dense plasmas. Furthermore their mono-chromaticity and collimation make them interesting tools in plasma physics but also in many biology or chemistry experiments. The effective use of this diagnostic is mainly depending on its dimensions and cost. For this reason, research on X ray laser is now focused on the reduction of cost and the realization of table-top facilities. One of these research axis, based on the optical field induced ionization (OFI) of the plasma, is presented in this work. An ultra-short (60 fs) high-brightness (10{sup 19} W/cm{sup 2}) Ti:Sapphire (790 nm) laser is focused into a nitrogen pulsed gas jet. A dense (10{sup 20} cm{sup -3}) plasma of fully stripped nitrogen is created by the way. During the fast recombination of the plasma some population inversions between levels of principal quantum number 2 and 1 (2.4 nm) and 3 and 2 (13.4 nm) can occur depending on the plasma parameters. The creation of the plasma by OFI, laser-plasma interaction dominated by relativistic self-focusing, and recombination dynamics are studied by numerical simulations on one hand and experiments on the other hand. Temperature measurements and numerical simulations show a strong heating, destructive for the laser scheme, which can be explained by Raman instability growing. Nevertheless plasma X ray emission in the 2-20 nm range show a strong increase with the electronic density of the 13.4 nm line intensity. This behavior is consistent with a laser effect but is not detected on the 2.4 nm transition line. (author)

Interaction of High Intensity Electromagnetic Waves with Plasmas: Final Report

International Nuclear Information System (INIS)

Shvets, G.

2008-01-01

The focus of our work during the duration of this grant was on the following areas: (a) the fundamental plasma physics of intense laser-plasma interactions, including the nonlinear excitation of plasma waves for accelerator applications, as well as the recently discovered by us phenomenon of the relativistic bi-stability of relativistic plasma waves driven by a laser beatwave; (b) interaction of high power microwave beams with magnetized plasma, including some of the recently discovered by us phenomena such as the Undulator Induced Transparency (UIT) as well as the new approaches to dynamic manipulation of microwave pulses; (c) investigations of the multi-color laser pulse interactions in the plasma, including the recently discovered by us phenomenon of Electromagnetic Cascading (EC) and the effect of the EC of three-dimensional dynamics of laser pulses (enhanced/suppressed selffocusing etc.); (d) interaction of high-current electron beams with the ambient plasma in the context of Fast Ignitor (FI) physics, with the emphasis on the nonlinear dynamics of the Weibel instability and beam filamentation.

Direct current plasma jet at atmospheric pressure operating in nitrogen and air

Science.gov (United States)

Deng, X. L.; Nikiforov, A. Yu.; Vanraes, P.; Leys, Ch.

2013-01-01

An atmospheric pressure direct current (DC) plasma jet is investigated in N2 and dry air in terms of plasma properties and generation of active species in the active zone and the afterglow. The influence of working gases and the discharge current on plasma parameters and afterglow properties are studied. The electrical diagnostics show that discharge can be sustained in two different operating modes, depending on the current range: a self-pulsing regime at low current and a glow regime at high current. The gas temperature and the N2 vibrational temperature in the active zone of the jet and in the afterglow are determined by means of emission spectroscopy, based on fitting spectra of N2 second positive system (C3Π-B3Π) and the Boltzmann plot method, respectively. The spectra and temperature differences between the N2 and the air plasma jet are presented and analyzed. Space-resolved ozone and nitric oxide density measurements are carried out in the afterglow of the jet. The density of ozone, which is formed in the afterglow of nitrogen plasma jet, is quantitatively detected by an ozone monitor. The density of nitric oxide, which is generated only in the air plasma jet, is determined by means of mass-spectroscopy techniques.

Effect of nitrogen environment on NdFeB thin films grown by radio frequency plasma beam assisted pulsed laser deposition

International Nuclear Information System (INIS)

Constantinescu, C.; Patroi, E.; Codescu, M.; Dinescu, M.

2013-01-01

Highlights: ► NdFeB thin films grown by PLD, in vacuum and in nitrogen, are presented. ► Nitrogen inclusion in thin film structures is related to improved coercitivity. ► Magnetical, optical and morphological properties of the thin films are discussed. - Abstract: NdFeB is a very attractive material for applications in electrical engineering and in electronics, for high-tech devices where high coercive field and high remanence are needed. In this paper we demonstrate that the deposition of nitrogen doped NdFeB thin films by pulsed laser deposition, in the presence of a nitrogen radiofrequency plasma beam, exhibit improved magnetic properties and surface morphology, when compared to vacuum deposited NdFeB layers. A Nd:YAG pulsed laser (3ω and 4ω) was focused on a NdFeB target, in vacuum, or in the presence of a nitrogen plasma beam. Substrate temperature (RT-850 °C), nitrogen gas pressure, and radiofrequency power (75–150 W), were particularly varied. The thin films were investigated by means of X-ray diffraction, atomic force microscopy, scanning electron microscopy, spectroscopic-ellipsometry, and vibrating sample magnetometry.

Effect of nitrogen environment on NdFeB thin films grown by radio frequency plasma beam assisted pulsed laser deposition

Energy Technology Data Exchange (ETDEWEB)

Constantinescu, C., E-mail: catalin.constantinescu@inflpr.ro [National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor bd., Magurele, RO-077125, Bucharest (Romania); Patroi, E.; Codescu, M. [National Institute for Research and Development in Electrical Engineering - Advanced Research, 313 Spl. Unirii, Sector 3, RO-030138, Bucharest (Romania); Dinescu, M. [National Institute for Laser, Plasma and Radiation Physics, 409 Atomistilor bd., Magurele, RO-077125, Bucharest (Romania)

2013-03-01

Highlights: Black-Right-Pointing-Pointer NdFeB thin films grown by PLD, in vacuum and in nitrogen, are presented. Black-Right-Pointing-Pointer Nitrogen inclusion in thin film structures is related to improved coercitivity. Black-Right-Pointing-Pointer Magnetical, optical and morphological properties of the thin films are discussed. - Abstract: NdFeB is a very attractive material for applications in electrical engineering and in electronics, for high-tech devices where high coercive field and high remanence are needed. In this paper we demonstrate that the deposition of nitrogen doped NdFeB thin films by pulsed laser deposition, in the presence of a nitrogen radiofrequency plasma beam, exhibit improved magnetic properties and surface morphology, when compared to vacuum deposited NdFeB layers. A Nd:YAG pulsed laser (3{omega} and 4{omega}) was focused on a NdFeB target, in vacuum, or in the presence of a nitrogen plasma beam. Substrate temperature (RT-850 Degree-Sign C), nitrogen gas pressure, and radiofrequency power (75-150 W), were particularly varied. The thin films were investigated by means of X-ray diffraction, atomic force microscopy, scanning electron microscopy, spectroscopic-ellipsometry, and vibrating sample magnetometry.

Nonlinear propagation of intense electromagnetic waves in weakly-ionized plasmas

International Nuclear Information System (INIS)

Shukla, P.K.

1993-01-01

The nonlinear propagation of intense electromagnetic waves in weakly-ionized plasmas is considered. Stimulated scattering mechanisms involving electromagnetic and acoustic waves in an unmagnetized plasma are investigated. The growth rate and threshold for three-wave decay interactions as well as modulational and filamentation instabilities are presented. Furthermore, the electromagnetic wave modulation theory is generalized for weakly ionized collisional magnetoplasmas. Here, the radiation envelope is generally governed by a nonlinear Schroedinger equation. Accounting for the dependence of the attachment frequency on the radiation intensity, ponderomotive force, as well as the differential Joule heating nonlinearity, the authors derive the equations for the nonthermal electron density and temperature perturbations. The various nonlinear terms in the electron motion are compared. The problems of self-focusing and wave localization are discussed. The relevance of the investigation to ionospheric modification by powerful electromagnetic waves is pointed out

Plasma basic concepts and nitrogen containing plasmas

OpenAIRE

Sanz Lluch, M. del Mar; Tanarro, Isabel

2007-01-01

Basic concepts related to plasmas are described as well as the typical characterization methods currently available. A brief overview about some plasma applications is given, but focusing on plasma used in material processing mainly devoted to the microelectronics industry. Finally, specific applications related to plasma-assisted MBE for nitrides and dilute nitrides are given, showing some interesting research works performed to that purpose, and giving the usual characterization techniques ...

Effect of suprathermal electrons on the intensity and Doppler frequency of electron plasma lines

Directory of Open Access Journals (Sweden)

P. Guio

Full Text Available In an incoherent scattering radar experiment, the spectral measurement of the so-called up- and downshifted electron plasma lines provides information about their intensity and their Doppler frequency. These two spectral lines correspond, in the backscatter geometry, to two Langmuir waves travelling towards and away from the radar. In the daytime ionosphere, the presence of a small percentage of photoelectrons produced by the solar EUV of the total electron population can excite or damp these Langmuir waves above the thermal equilibrium, resulting in an enhancement of the intensity of the lines above the thermal level. The presence of photo-electrons also modifies the dielectric response function of the plasma from the Maxwellian and thus influences the Doppler frequency of the plasma lines. In this paper, we present a high time-resolution plasma-line data set collected on the Eiscat VHF radar. The analysed data are compared with a model that includes the effect of a suprathermal electron population calculated by a transport code. By comparing the intensity of the analysed plasma lines data to our model, we show that two sharp peaks in the electron suprathermal distribution in the energy range 20-30 eV causes an increased Landau damping around 24.25 eV and 26.25 eV. We have identified these two sharp peaks as the effect of the photoionisation of N₂ and O by the intense flux of monochromatic HeII radiation of wavelength 30.378 nm (40.812 eV created in the chromospheric network and coronal holes. Furthermore, we see that what would have been interpreted as a mean Doppler drift velocity for a Maxwellian plasma is actually a shift of the Doppler frequency of the plasma lines due to suprathermal electrons.

Key words. Ionosphere (electric fields and currents; solar radiation and cosmic ray effects

Effect of suprathermal electrons on the intensity and Doppler frequency of electron plasma lines

Directory of Open Access Journals (Sweden)

P. Guio

1999-07-01

Full Text Available In an incoherent scattering radar experiment, the spectral measurement of the so-called up- and downshifted electron plasma lines provides information about their intensity and their Doppler frequency. These two spectral lines correspond, in the backscatter geometry, to two Langmuir waves travelling towards and away from the radar. In the daytime ionosphere, the presence of a small percentage of photoelectrons produced by the solar EUV of the total electron population can excite or damp these Langmuir waves above the thermal equilibrium, resulting in an enhancement of the intensity of the lines above the thermal level. The presence of photo-electrons also modifies the dielectric response function of the plasma from the Maxwellian and thus influences the Doppler frequency of the plasma lines. In this paper, we present a high time-resolution plasma-line data set collected on the Eiscat VHF radar. The analysed data are compared with a model that includes the effect of a suprathermal electron population calculated by a transport code. By comparing the intensity of the analysed plasma lines data to our model, we show that two sharp peaks in the electron suprathermal distribution in the energy range 20-30 eV causes an increased Landau damping around 24.25 eV and 26.25 eV. We have identified these two sharp peaks as the effect of the photoionisation of N2 and O by the intense flux of monochromatic HeII radiation of wavelength 30.378 nm (40.812 eV created in the chromospheric network and coronal holes. Furthermore, we see that what would have been interpreted as a mean Doppler drift velocity for a Maxwellian plasma is actually a shift of the Doppler frequency of the plasma lines due to suprathermal electrons.Key words. Ionosphere (electric fields and currents; solar radiation and cosmic ray effects

Influence of carbohydrate addition on nitrogen transformations and greenhouse gas emissions of intensive aquaculture system.

Science.gov (United States)

Hu, Zhen; Lee, Jae Woo; Chandran, Kartik; Kim, Sungpyo; Sharma, Keshab; Khanal, Samir Kumar

2014-02-01

Aquaculture is one of the fastest-growing segments of the food economy in modern times. It is also being considered as an important source of greenhouse gas (GHG) emissions. To date, limited studies have been conducted on GHG emissions from aquaculture system. In this study, daily addition of fish feed and soluble starch at a carbon-to-nitrogen (C/N) ratio of 16:1 (w/w) was used to examine the effects of carbohydrate addition on nitrogen transformations and GHG emissions in a zero-water exchange intensive aquaculture system. The addition of soluble starch stimulated heterotrophic bacterial growth and denitrification, which led to lower total ammonia nitrogen, nitrite and nitrate concentrations in aqueous phase. About 76.2% of the nitrogen output was emitted in the form of gaseous nitrogen (i.e., N2 and N2O) in the treatment tank (i.e., aquaculture tank with soluble starch addition), while gaseous nitrogen accounted for 33.3% of the nitrogen output in the control tank (i.e., aquaculture tank without soluble starch addition). Although soluble starch addition reduced daily N2O emissions by 83.4%, it resulted in an increase of daily carbon dioxide (CO2) emissions by 91.1%. Overall, starch addition did not contribute to controlling the GHG emissions from the aquaculture system. © 2013.

A pulsed plasma jet with the various Ar/N2 mixtures

Science.gov (United States)

Barkhordari, A.; Ganjovi, A.; Mirzaei, I.; Falahat, A.; Rostami Ravari, M. N.

2017-12-01

In this paper, using the Optical Emission Spectroscopy technique, the physical properties of a fabricated pulsed DBD plasma jet are studied. Ar/N2 gaseous mixture is taken as operational gas, and Ar contribution in Ar/N2 mixture is varied from 75 to 95%. Through the optical emission spectra analysis of the pulsed DBD plasma jet, the rotational, vibrational and excitation temperatures and density of electrons in plasma medium of the pulsed plasma jet are obtained. It is seen that, at the wavelength of 750.38 nm, the radiation intensity from the Ar 4p → 4 s transition increases at the higher Ar contributions in Ar/N2 mixture. It is found that, for 95% of Ar presence in the mixture, the emission intensities from argon and molecular nitrogen are higher, and the emission line intensities will increase nonlinearly. In addition, it is observed that the quenching of Ar* by N2 results in the higher intensities of N2 excited molecules. Moreover, at the higher percentages of Ar in Ar/N2 mixture, while all the plasma temperatures are increased, the plasma electron density is reduced.

Dependence of high order harmonics intensity on laser focal spot position in preformed plasma plumes

International Nuclear Information System (INIS)

Singhal, H.; Ganeev, R.; Naik, P. A.; Arora, V.; Chakravarty, U.; Gupta, P. D.

2008-01-01

The dependence of the high-order harmonic intensity on the laser focal spot position in laser produced plasma plumes is experimentally studied. High order harmonics up to the 59th order (λ∼13.5 nm) were generated by focusing 48 fs laser pulses from a Ti:sapphire laser system in silver plasma plume produced using 300 ps uncompressed laser radiation as the prepulse. The intensity of harmonics nearly vanished when the best focus was located in the plume center, whereas it peaked on either side with unequal intensity. The focal spot position corresponding to the peak harmonic intensity moved away from the plume center for higher order harmonics. The results are explained in terms of the variation of phase mismatch between the driving laser beam and harmonics radiation produced, relativistic drift of electrons, and defocusing effect due to radial ionization gradient in the plasma for different focal spot positions

Physics of Neutralization of Intense Charged Particle Beam Pulses by a Background Plasma

International Nuclear Information System (INIS)

Kaganovich, I.D.; Davidson, R.C.; Dorf, M.A.; Startsev, E.A.; Sefkow, A.B; Friedman, A.F.; Lee, E.P.

2009-01-01

Neutralization and focusing of intense charged particle beam pulses by a background plasma forms the basis for a wide range of applications to high energy accelerators and colliders, heavy ion fusion, and astrophysics. For example, for ballistic propagation of intense ion beam pulses, background plasma can be used to effectively neutralize the beam charge and current, so that the self-electric and self-magnetic fields do not affect the ballistic propagation of the beam. From the practical perspective of designing advanced plasma sources for beam neutralization, a robust theory should be able to predict the self-electric and self-magnetic fields during beam propagation through the background plasma. The major scaling relations for the self-electric and self-magnetic fields of intense ion charge bunches propagating through background plasma have been determined taking into account the effects of transients during beam entry into the plasma, the excitation of collective plasma waves, the effects of gas ionization, finite electron temperature, and applied solenoidal and dipole magnetic fields. Accounting for plasma production by gas ionization yields a larger self-magnetic field of the ion beam compared to the case without ionization, and a wake of current density and self-magnetic field perturbations is generated behind the beam pulse. A solenoidal magnetic field can be applied for controlling the beam propagation. Making use of theoretical models and advanced numerical simulations, it is shown that even a small applied magnetic field of about 100G can strongly affect the beam neutralization. It has also been demonstrated that in the presence of an applied magnetic field the ion beam pulse can excite large-amplitude whistler waves, thereby producing a complex structure of self-electric and self-magnetic fields. The presence of an applied solenoidal magnetic field may also cause a strong enhancement of the radial self-electric field of the beam pulse propagating

Pondermotive absorption of a short intense laser pulse in a non-uniform plasma

Energy Technology Data Exchange (ETDEWEB)

Andreev, A A; Platonov, K Yu [Inst. for Laser Physics, SC ` Vavilov State Optical Inst.` 12, Birzhevaya line, St Petersburg (Russian Federation); Tanaka, K A

1998-03-01

An analytical description of the pondermotive absorption mechanism at a short high intense laser pulse interaction with a strong inhomogeneous plasma is presented. The optimal conditions for the maximum of resonance absorption of laser pulse interaction with non-uniform plasma at normal incidence are founded. (author)

On the anomalous interaction of intense light fluxes with a dense plasma

International Nuclear Information System (INIS)

D'yachenko, V.F.; Imshennik, V.S.

1979-01-01

The process of interaction of a light wave with plasma is considered in the framework of the system of the Maxwell-Vlasov equations without taking accout of particle collisions. The plasma were incident onto the plasma surface is monochromatic and linearly polarized. Plasma is cold and completely ionized. The concentration of charged particles is above critical one and varies in the direction of vector of the wave electric field. The results of several numerical calculations of this problem are presented. They show that if the energy flux density of the wave exceeds some critical one, plasma absorbes light intensively. Studied is the mechanism of nonlinear interaction of oscillations which leads to arising of multiflux motion and explaining this effect

Control of ion content and nitrogen species using a mixed chemistry plasma for GaN grown at extremely high growth rates >9 μm/h by plasma-assisted molecular beam epitaxy

Science.gov (United States)

Gunning, Brendan P.; Clinton, Evan A.; Merola, Joseph J.; Doolittle, W. Alan; Bresnahan, Rich C.

2015-10-01

Utilizing a modified nitrogen plasma source, plasma assisted molecular beam epitaxy (PAMBE) has been used to achieve higher growth rates in GaN. A higher conductance aperture plate, combined with higher nitrogen flow and added pumping capacity, resulted in dramatically increased growth rates up to 8.4 μm/h using 34 sccm of N2 while still maintaining acceptably low operating pressure. It was further discovered that argon could be added to the plasma gas to enhance growth rates up to 9.8 μm/h, which was achieved using 20 sccm of N2 and 7.7 sccm Ar flows at 600 W radio frequency power, for which the standard deviation of thickness was just 2% over a full 2 in. diameter wafer. A remote Langmuir style probe employing the flux gauge was used to indirectly measure the relative ion content in the plasma. The use of argon dilution at low plasma pressures resulted in a dramatic reduction of the plasma ion current by more than half, while high plasma pressures suppressed ion content regardless of plasma gas chemistry. Moreover, different trends are apparent for the molecular and atomic nitrogen species generated by varying pressure and nitrogen composition in the plasma. Argon dilution resulted in nearly an order of magnitude achievable growth rate range from 1 μm/h to nearly 10 μm/h. Even for films grown at more than 6 μm/h, the surface morphology remained smooth showing clear atomic steps with root mean square roughness less than 1 nm. Due to the low vapor pressure of Si, Ge was explored as an alternative n-type dopant for high growth rate applications. Electron concentrations from 2.2 × 1016 to 3.8 × 1019 cm-3 were achieved in GaN using Ge doping, and unintentionally doped GaN films exhibited low background electron concentrations of just 1-2 × 1015 cm-3. The highest growth rates resulted in macroscopic surface features due to Ga cell spitting, which is an engineering challenge still to be addressed. Nonetheless, the dramatically enhanced growth rates demonstrate

Investigations of Nitrogen Oxide Plasmas: Fundamental Chemistry and Surface Reactivity and Monitoring Student Perceptions in a General Chemistry Recitation

Science.gov (United States)

Blechle, Joshua M.

2016-01-01

Part I of this dissertation focuses on investigations of nitrogen oxide plasma systems. With increasing concerns over the environmental presence of NxOy species, there is growing interest in utilizing plasma-assisted conversion techniques. Advances, however, have been limited because of the lack of knowledge regarding the fundamental chemistry of…

A high-intensity plasma-sputter heavy negative ion source

International Nuclear Information System (INIS)

Alton, G.D.; Mori, Y.; Takagi, A.; Ueno, A.; Fukumoto, S.

1989-01-01

A multicusp magnetic field plasma surface ion source, normally used for H/sup /minus//ion beam formation, has been modified for the generation of high-intensity, pulsed, heavy negative ion beams suitable for a variety of uses. To date, the source has been utilized to produce mA intensity pulsed beams of more than 24 species. A brief description of the source, and basic pulsed-mode operational data, (e.g., intensity versus cesium oven temperature, sputter probe voltage, and discharge pressure), are given. In addition, illustrative examples of intensity versus time and the mass distributions of ion beams extracted from a number of samples along with emittance data, are also presented. Preliminary results obtained during dc operation of the source under low discharge power conditions suggest that sources of this type may also be used to produce high-intensity (mA) dc beams. The results of these investigations are given, as well, and the technical issues that must be addressed for this mode of operation are discussed. 15 refs., 10 figs., 2 tabs

Study of ultra-high gradient wakefield excitation by intense ultrashort laser pulses in plasma

International Nuclear Information System (INIS)

Kotaki, Hideyuki

2002-12-01

We investigate a mechanism of nonlinear phenomena in laser-plasma interaction, a laser wakefield excited by intense laser pulses, and the possibility of generating an intense bright electron source by an intense laser pulse. We need to understand and further employ some of these phenomena for our purposes. We measure self-focusing, filamentation, and the anomalous blueshift of the laser pulse. The ionization of gas with the self-focusing causes a broad continuous spectrum with blueshift. The normal blueshift depends on the laser intensity and the plasma density. We, however, have found different phenomenon. The laser spectrum shifts to fixed wavelength independent of the laser power and gas pressure above some critical power. We call the phenomenon 'anomalous blueshift'. The results are explained by the formation of filaments. An intense laser pulse can excite a laser wakefield in plasma. The coherent wakefield excited by 2 TW, 50 fs laser pulses in a gas-jet plasma around 10 18 cm -3 is measured with a time-resolved frequency domain interferometer (FDI). The density distribution of the helium gas is measured with a time-resolved Mach-Zehnder interferometer to search for the optimum laser focus position and timing in the gas-jet. The results show an accelerating wakefield excitation of 20 GeV/m with good coherency, which is useful for ultrahigh gradient particle acceleration in a compact system. This is the first time-resolved measurement of laser wakefield excitation in a gas-jet plasma. The experimental results are compared with a Particle-in-Cell (PIC) simulation. The pump-probe interferometer system of FDI and the anomalous blueshift will be modified to the optical injection system as a relativistic electron beam injector. In 1D PIC simulation we obtain the results of high quality intense electron beam acceleration. These results illuminate the possibility of a high energy and a high quality electron beam acceleration. (author)

Electron acceleration by femtosecond laser interaction with micro-structured plasmas

Science.gov (United States)

Goers, Andy James

Laser-driven accelerators are a promising and compact alternative to RF accelerator technology for generating relativistic electron bunches for medical, scientific, and security applications. This dissertation presents three experiments using structured plasmas designed to advance the state of the art in laser-based electron accelerators, with the goal of reducing the energy of the drive laser pulse and enabling higher repetition rate operation with current laser technology. First, electron acceleration by intense femtosecond laser pulses in He-like nitrogen plasma waveguides is demonstrated. Second, significant progress toward a proof of concept realization of quasi-phasematched direct acceleration (QPM-DLA) is presented. Finally, a laser wakefield accelerator at very high plasma density is studied, enabling relativistic electron beam generation with ˜10 mJ pulse energies. Major results from these experiments include: • Acceleration of electrons up to 120 MeV from an ionization injected wakefield accelerator driven in a 1.5 mm long He-like nitrogen plasma waveguide • Guiding of an intense, quasi-radially polarized femtosecond laser pulse in a 1 cm plasma waveguide. This pulse provides a strong drive field for the QPM-DLA concept. • Wakefield acceleration of electrons up to ˜10 MeV with sub-terawatt, ˜10 mJ pulses interacting with a thin (˜200 mum), high density (>1020 cm-3) plasma. • Observation of an intense, coherent, broadband wave breaking radiation flash from a high plasma density laser wakefield accelerator. The flash radiates > 1% of the drive laser pulse energy in a bandwidth consistent with half-cycle (˜1 fs) emission from violent unidirectional acceleration of electron bunches from rest. These results open the way to high repetition rate (>˜kHz) laser-driven generation of relativistic electron beams with existing laser technology.

Structural Transformation upon Nitrogen Doping of Ultrananocrystalline Diamond Films by Microwave Plasma CVD

Directory of Open Access Journals (Sweden)

Chien-Chung Teng

2009-01-01

Full Text Available The molecular properties and surface morphology of undoped and N-doped ultra-nanocrystalline diamond (UNCD films deposited by microwave plasma CVD with addition of nitrogen are investigated with various spectroscopic techniques. The results of spatially resolved Raman scattering, ATR/FT-IR and XPS spectra show more amorphous and sp2/sp3 ratio characteristics in N-doped UNCD films. The surface morphology in AFM scans shows larger nanocrystalline diamond clusters in N-doped UNCD films. Incorporation of nitrogen into UNCD films has promoted an increase of amorphous sp2-bonded carbons in the grain boundaries and the size of nanocrystalline diamond grains that are well correlated to the reported enhancement of conductivity and structural changes of UNCD films.

Dynamics of a collisionless plasma interacting with an ultra-intense laser pulse

International Nuclear Information System (INIS)

Capdessus, Remi

2013-01-01

The interaction of a plasma with an ultra-intense laser pulse becomes more and more interesting as a result of the advances made in terms of numerical tools laser technology. The radiation reaction impacts the electrons dynamics, those of the synchrotron radiation as well as those of the ions by means of charge separation field, for laser intensities above 10 22 W/cm 2 . The kinetic equations governing the particles transport at ultra-high intensity have been obtained. The radiation reaction involves the shrinkage of the space volume of the electrons phases. It has been shown with numerical simulations the strong retro-action that the collective effects induce on the synchrotron radiation generated by the accelerated electrons. The importance of the collective effects depends strongly on the ions mass and of the thickness of the considered plasma. These effects could be verified experimentally with hydrogen cryogenic targets. (author) [fr

Nitrogen balance, plasma free amino acid concentrations and urinary orotic acid excretion during long-term fasting in cats.

Science.gov (United States)

Biourge, V; Groff, J M; Fisher, C; Bee, D; Morris, J G; Rogers, Q R

1994-07-01

The purpose of this study was to ascertain the changes in nitrogen balance, plasma free amino acid concentrations, urinary orotic acid excretion and body weight during long-term fasting in adult obese cats. Results from eight cats that fasted rather than eat an unpalatable diet are reported. After 5 to 6 wk of weight loss, six of the eight cats developed signs of hepatic lipidosis, and the livers of all cats were severely infiltrated with lipids. Cats lost (mean +/- SE) 33.2 +/- 1.4% of their pre-fasting body weight. Mean nitrogen balance (+/- SE) was -547 +/- 54 mg.d-1.kg-2/3 for the first week, and then the net nitrogen losses decreased to a plateau (-303 +/- 52 mg.d-1.kg-2/3) after 4 wk. Fasting was associated with a decrease in plasma concentration of essential amino acids. When plasma amino acid concentrations were considered individually, concentrations of alanine, methionine, taurine, citrulline, arginine and tryptophan decreased the most (> or = 50%), whereas concentrations of glutamine, glutamate and ornithine significantly increased. Orotic acid was not detected in the urine during the fast. After 1 wk of fasting, obese cats had reduced nitrogen excretion, but not to the same extent as has been shown in obese humans or obese rats. It is suggested that the availability of several amino acids may become limiting for liver protein synthesis during fasting and that these deficiencies may contribute to the development of hepatic lipidosis. Orotic acid was not linked to hepatic lipidosis caused by fasting in cats.

Kr photoionized plasma induced by intense extreme ultraviolet pulses

Science.gov (United States)

Bartnik, A.; Wachulak, P.; Fiedorowicz, H.; Skrzeczanowski, W.

2016-04-01

Irradiation of any gas with an intense EUV (extreme ultraviolet) radiation beam can result in creation of photoionized plasmas. The parameters of such plasmas can be significantly different when compared with those of the laser produced plasmas (LPP) or discharge plasmas. In this work, the photoionized plasmas were created in a krypton gas irradiated using an LPP EUV source operating at a 10 Hz repetition rate. The Kr gas was injected into the vacuum chamber synchronously with the EUV radiation pulses. The EUV beam was focused onto a Kr gas stream using an axisymmetrical ellipsoidal collector. The resulting low temperature Kr plasmas emitted electromagnetic radiation in the wide spectral range. The emission spectra were measured either in the EUV or an optical range. The EUV spectrum was dominated by emission lines originating from Kr III and Kr IV ions, and the UV/VIS spectra were composed from Kr II and Kr I lines. The spectral lines recorded in EUV, UV, and VIS ranges were used for the construction of Boltzmann plots to be used for the estimation of the electron temperature. It was shown that for the lowest Kr III and Kr IV levels, the local thermodynamic equilibrium (LTE) conditions were not fulfilled. The electron temperature was thus estimated based on Kr II and Kr I species where the partial LTE conditions could be expected.

Mechanism for heating of nitrogen plasmas in an electrodeless rf capacitive discharge at medium pressures

International Nuclear Information System (INIS)

Berdichevskii, M.G.; Marusin, V.V.

1979-01-01

The possible contributions of several processes to the experimentally observed heating of nitrogen plasmas in an electarodeless rf capacitive discharge at pressures of p=2.7-67 kPa are discussed. These processes are electron-rotational, vibrational--translational (V--T), and nonresonance vibrational--vibrational (V--V) energy exchange and effects due to O 2 , H 2 O, and NO impurities in the gas. It is shown that as the pressure is decreased the heating mechanism changes from quasiequilibrium to nonequilibrium V--T heating caused by overpopulation of high vibrational levels in the ground state of the nitrogen molecule

Morphological characteristics of the interspecies hybrid between Sorghum and Sudan grass under intensive nitrogen nutrition

Directory of Open Access Journals (Sweden)

Ikanović Jela

2013-01-01

Full Text Available The object of this study was a two-year trial (2009 and 2010 regarding variability of morphological characteristics of species belonging to Sorghum genus, more specifically interspecies hybrid between sorghum and Sudan grass Siloking as affected by different applications of nitrogen. The following morphological characteristics were analysed: plant height, number of leaves, leaf ratio, stem ratio, and number of shoots. Samples were taken from the first cut when the effect of the applied nitrogen doses was the strongest. The results showed that increasing nitrogen quantities significantly affected the tested morphological characteristics, especially the intensity of tillering (increased number of secondary stems, number of the formed leaves, and ratio of leaf weight in the total above-ground biomass. The effect of applied nitrogen depended on the weather conditions, i.e. distribution of precipitation, so that plants reached maximum height when 105 kg N ha-1 was applied in the dry year and 180 kg N ha-1 in the wet year. [Projekat Ministarstva nauke Republike Srbije, br. TR 31078 i br. TR 31022

Plasma Irisin Modestly Increases during Moderate and High-Intensity Afternoon Exercise in Obese Females

Science.gov (United States)

Winn, Nathan C.; Grunewald, Zachary I.; Liu, Ying; Heden, Timothy D.; Nyhoff, Lauren M.; Kanaley, Jill A.

2017-01-01

Background and Purpose Irisin is an exercise-responsive myokine that has been proposed to exert anti-obesity benefits; yet its response during exercise in obese women is not described. This study characterized plasma irisin levels during a single bout of afternoon isocaloric-exercise of different intensities (moderate- vs high-intensity) in obese females. Methods Eleven obese females participated in 3 randomized study days beginning at 1600h: 1) no exercise (NoEx), 2) moderate exercise (ModEx; 55%VO2max) and 3) high intensity interval exercise (IntEx; 4 min (80%VO2max)/3 min (50% VO2max). Frequent blood samples were analyzed for glucose and lactate (whole-blood), and insulin, c-peptide, glucagon, and irisin (plasma) throughout 190 min of testing. Results Plasma irisin increased above baseline during ModEx and IntEx (P0.05). Peak irisin levels during ModEx and IntEx exercise were 11.9± 3.4% and 12.3 ± 4.1% relative to baseline (Pexercise intensities (P>0.05). Irisin levels remained elevated above resting for 125 minutes post-exercise during ModEx, whereas levels returned to baseline within 15 minutes post-exercise during IntEx. Similarly, no associations were found between plasma irisin levels and circulating lactate, glucose, insulin, c-peptide, or glucagon among study days (P>0.05). However, there was an inverse association between basal irisin and lean mass (r = -0.70, P = 0.01). Conclusion A single bout of moderate and high intensity afternoon exercise induces modest increases in circulating irisin concentrations during exercise; however the regulation post-exercise appears to be dimorphic between exercise intensity in obese females. Future studies are needed to compare morning and afternoon exercise on irisin secretion. PMID:28125733

Observations of MeV electrons and scattered light from intense, subpicosecond laser-plasma interactions

International Nuclear Information System (INIS)

Darrow, C.; Lane, S.; Klem, D.; Perry, M.D.

1993-01-01

In this paper the authors present work in progress in their experimental investigation of the coupling of intense, subpicosecond laser pulses with plasmas preformed on solid targets. (This situation is to be contrasted with the interaction of intense laser fields with solid-density matter. A subject which has generated considerable interest in the last several years.) The characterization of the energy distribution of energetic electrons which escape a solid target irradiated by an intense laser is discussed. The authors have also performed experiments to study the excitation of parametric instabilities near the quarter-critical layer and second-harmonic generation near the critical layer in the plasma. They discuss some preliminary scattered light spectroscopy measurements

Combination of the ionic-to-atomic line intensity ratios from two test elements for the diagnostic of plasma temperature and electron number density in Inductively Coupled Plasma Atomic Emission Spectroscopy

Energy Technology Data Exchange (ETDEWEB)

Tognoni, E. [Istituto per i Processi Chimico-Fisici, Area della Ricerca del Consiglio Nazionale delle Ricerche Via Moruzzi 1, 56124 Pisa (Italy)], E-mail: tognoni@ipcf.cnr.it; Hidalgo, M.; Canals, A. [Departamento de Quimica Analitica, Nutricion y Bromatologia. Universidad de Alicante. Apdo. 99, 03080, Alicante (Spain); Cristoforetti, G.; Legnaioli, S.; Salvetti, A.; Palleschi, V. [Istituto per i Processi Chimico-Fisici, Area della Ricerca del Consiglio Nazionale delle Ricerche Via Moruzzi 1, 56124 Pisa (Italy)

2007-05-15

In Inductively Coupled Plasma-Atomic Emission Spectroscopy (ICP-AES) spectrochemical analysis, the MgII(280.270 nm)/MgI(285.213 nm) ionic to atomic line intensity ratio is commonly used as a monitor of the robustness of operating conditions. This approach is based on the univocal relationship existing between intensity ratio and plasma temperature, for a pure argon atmospheric ICP in thermodynamic equilibrium. In a multi-elemental plasma in the lower temperature range, the measurement of the intensity ratio may not be sufficient to characterize temperature and electron density. In such a range, the correct relationship between intensity ratio and plasma temperature can be calculated only when the complete plasma composition is known. We propose the combination of the line intensity ratios of two test elements (double ratio) as an effective diagnostic tool for a multi-elemental low temperature LTE plasma of unknown composition. In particular, the variation of the double ratio allows us discriminating changes in the plasma temperature from changes in the electron density. Thus, the effects on plasma excitation and ionization possibly caused by introduction of different samples and matrices in non-robust conditions can be more accurately interpreted. The method is illustrated by the measurement of plasma temperature and electron density in a specific analytic case.

Fast photography of XeCl laser-induced plasma of graphite in vacuum and in nitrogen atmosphere

International Nuclear Information System (INIS)

Acquaviva, S; De Giorgi, M L

2003-01-01

Fast photography with a gated intensified close-coupled device camera was applied to provide a visualization of the temporal and spatial evolution of chemical species in a plasma induced by a 308 nm laser during graphite ablation, in vacuum and in nitrogen atmosphere. A sequence of frames of the luminous plume was recorded, using narrow interference filters, and plasma expansion velocity was estimated from the acquired images. Present observations agree with optical emission spectroscopic investigations performed under the same experimental conditions

Diagnosis of high-intensity pulsed heavy ion beam generated by a novel magnetically insulated diode with gas puff plasma gun.

Science.gov (United States)

Ito, H; Miyake, H; Masugata, K

2008-10-01

Intense pulsed heavy ion beam is expected to be applied to materials processing including surface modification and ion implantation. For those applications, it is very important to generate high-purity ion beams with various ion species. For this purpose, we have developed a new type of a magnetically insulated ion diode with an active ion source of a gas puff plasma gun. When the ion diode was operated at a diode voltage of about 190 kV, a diode current of about 15 kA, and a pulse duration of about 100 ns, the ion beam with an ion current density of 54 A/cm(2) was obtained at 50 mm downstream from the anode. By evaluating the ion species and the energy spectrum of the ion beam via a Thomson parabola spectrometer, it was confirmed that the ion beam consists of nitrogen ions (N(+) and N(2+)) of energy of 100-400 keV and the proton impurities of energy of 90-200 keV. The purity of the beam was evaluated to be 94%. The high-purity pulsed nitrogen ion beam was successfully obtained by the developed ion diode system.

Plasma hydrodynamics of the intense laser-cluster interaction*

Science.gov (United States)

Milchberg, Howard

2002-11-01

We present a 1D hydrodynamic model of the intense laser-cluster interaction in which the laser field is treated self-consistently. We find that for clusters initially as small as 25Å in radius, for which the hydrodynamic model is appropriate, nonuniform expansion of the heated material results in long-time resonance of the laser field at the critical density plasma layer. A significant result of this is that the ponderomotive force, which is enhanced at the critical density surface, can be large enough to strongly modify the plasma hydrodynamics, even at laser intensities as low as 10^15 W/cm^2 for 800 nm laser pulses. Recent experiments in EUV and x-ray generation as a function of laser pulsewidth [1], and femtosecond time-resolved measurements of cluster transient polarizability [2] provide strong support for the basic physics of this model. Recent results using a 2D hybrid fluid/PIC code show qualitative agreement with the 1D hydrocode [3]. *Work supported by the National Science Foundation and the EUV-LLC. 1. E. Parra, I. Alexeev, J. Fan, K. Kim, S.J. McNaught, and H. M. Milchberg, Phys. Rev. E 62, R5931 (2000). 2. K.Y. Kim, I. Alexeev, E. Parra, and H.M. Milchberg, submitted for publication. 3. T. Taguchi, T. Antonsen, and H.M Milchberg, this meeting.

Impact of nitrogen plasma passivation on the Al/n-Ge contact

Energy Technology Data Exchange (ETDEWEB)

Lai, Shumei; Mao, Danfeng [Department of Physics, Xiamen University, Xiamen, Fujian 361005 (China); Ruan, Yujiao [Xiamen Institute of Measurement and Testing, Xiamen, Fujian 361004 (China); Xu, Yihong; Huang, Zhiwei; Huang, Wei [Department of Physics, Xiamen University, Xiamen, Fujian 361005 (China); Chen, Songyan, E-mail: sychen@xmu.edu.cn [Department of Physics, Xiamen University, Xiamen, Fujian 361005 (China); Li, Cheng; Wang, Jianyuan [Department of Physics, Xiamen University, Xiamen, Fujian 361005 (China); Tang, Dingliang [College of Chemistry and Chemical Engineering, Xiamen University, Xiamen, Fujian 361005 (China)

2016-09-15

Highlights: • A thin GeO{sub x}N{sub y} layer was formed by N{sub 2} plasma. • The principal parameters of N{sub 2} plasma treatment and additional post anneal have a great impact on the Al/n-Ge contact. • A model was proposed to explain the variation of Schottky barrier height. • The GeO{sub x}N{sub y} layer was also benefit to achieve a low leakage current density for HfO{sub 2}/Ge MOS capacitors. - Abstract: Severe Fermi level pinning at the interface of metal/n-Ge leads to the formation of a Schottky barrier. Therefore, a high contact resistance is introduced, debasing the performance of Ge devices. In this study, a Ge surface was treated by nitrogen plasma to form an ultra-thin Germanium oxynitride (GeO{sub x}N{sub y}) passivation layer. It was found that the Schottky barrier height (SBH) of metal/n-Ge contact was strongly modulated by the GeO{sub x}N{sub y} interlayer, indicating alleviation of Fermi-level pinning effect. By adjusting the principal parameters of N{sub 2} plasma treatment and additional post anneal, a Quasi-ohmic Al/n-Ge contact was achieved. Furthermore, the introduced GeO{sub x}N{sub y} layer gave extremely lower leakage current density of the gate stack for HfO{sub 2}/Ge devices. These results demonstrate that GeO{sub x}N{sub y} formed by N{sub 2} plasma would be greatly beneficial to the fabrication of the Ge-based devices.

Numerical modelling of radiation in 2+ and- systems of nitrogen accounting non-stationary excited states population in a streamer discharge

International Nuclear Information System (INIS)

Djakov, A.F.; Bobrov, J.K.; Jourguelenas, J.V.

2000-01-01

Measurement of spectral bands intensity allows to obtain a valuable information on plasma temperature and electron density - the parameters having critical influence on chemical reactions and efficiency of plasma chemistry applications. At present the interest in streamer discharges is becoming more important because of their applications to flue gas treatment and ozone generation. For a streamer discharge in air the molecular spectral bands of the second positive and first negative systems of nitrogen are the most intensive ones. However, both the registration of radiation and interpretation of the received data are very complicated problems. (Authors)

Enhancing Plasma Surface Modification using high Intensity and high Power Ultrasonic Acoustic Waves

DEFF Research Database (Denmark)

2010-01-01

high intensity and high power acoustic waves (102) by at least one ultrasonic high intensity and high power acoustic wave generator (101 ), wherein the ultrasonic acoustic waves are directed to propagate towards said surface (314) of the object (100) so that a laminar boundary layer (313) of a gas...... or a mixture of gases (500) flow in contact with said solid object (100) is thinned or destructed for at least a part of said surface (314). In this way, the plasma can more efficiently access and influence the surface of the solid object to be treated by the plasma, which speeds the process time up...

Photooptical response of the blood plasma to the low-intensity red light

International Nuclear Information System (INIS)

Mints, R.I.; Skopinov, S.A.; Yakovleva, S.V.

1990-01-01

Photooptical response to low-intensity red light by irradiation of the whole blood as well as of its pigmentless plasma part is investigated. It is shown by the example of blood irradiation that the mechanism of action of low-intensity red light on the blood is not directly related to pigmented molecular complexes. The conclusion is made, that the effect of low-intensity red light on living organisms includes mechanism not utilizing light absorption by a specialized molecule-photoreceptor as a primary photophysical act

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

Propagation of an intense laser beam in a tapered plasma channel

International Nuclear Information System (INIS)

Jha, Pallavi; Singh, Ram Gopal; Upadhyaya, Ajay K.; Mishra, Rohit K.

2008-01-01

Propagation characteristics and modulation instability of an intense laser beam propagating in an axially tapered plasma channel, having a parabolic radial density profile, are studied. Using the source-dependent expansion technique, the evolution equation for the laser spot is set up and conditions for propagation of the laser beam with a constant spot size (matched beam) are obtained. Further, the dispersion relation and growth rate of modulation instability of the laser pulse as it propagates through linearly and quadratically tapered plasma channels, have been obtained

Using self-generated harmonics as a diagnostic of high intensity laser-produced plasmas

International Nuclear Information System (INIS)

Krushelnick, K; Watts, I; Tatarakis, M; Gopal, A; Wagner, U; Beg, F N; Clark, E L; Clarke, R J; Dangor, A E; Norreys, P A; Wei, M S; Zepf, M

2002-01-01

The interaction of high intensity laser pulses (up to I∼10 20 W cm -2 ) with plasmas can generate very high order harmonics of the laser frequency (up to the 75th order have been observed). Measurements of the properties of these harmonics can provide important insights into the plasma conditions which exist during such interactions. For example, observations of the spectrum of the harmonic emission can provide information of the dynamics of the critical surface as well as information on relativistic non-linear optical effects in the plasma. However, most importantly, observations of the polarization properties of the harmonics can provide a method to measure the ultra-strong magnetic fields (greater than 350 MG) which can be generated during these interactions. It is likely that such techniques can be scaled to provide a significant amount of information from experiments at even higher intensities

Nonlinear interaction of an intense radio wave with ionospheric D/E layer plasma

Science.gov (United States)

Sodha, Mahendra Singh; Agarwal, Sujeet Kumar

2018-05-01

This paper considers the nonlinear interaction of an intense electromagnetic wave with the D/E layer plasma in the ionosphere. A simultaneous solution of the electromagnetic wave equation and the equations describing the kinetics of D/E layer plasma is obtained; the phenomenon of ohmic heating of electrons by the electric field of the wave causes enhanced collision frequency and ionization of neutral species. Electron temperature dependent recombination of electrons with ions, electron attachment to O 2 molecules, and detachment of electrons from O2 - ions has also been taken into account. The dependence of the plasma parameters on the square of the electric vector of the wave E0 2 has been evaluated for three ionospheric heights (viz., 90, 100, and 110 km) corresponding to the mid-latitude mid-day ionosphere and discussed; these results are used to investigate the horizontal propagation of an intense radio wave at these heights.

Irradiation of intense characteristic x-rays from weakly ionized linear molybdenum plasma

International Nuclear Information System (INIS)

Sato, Eiichi; Hayasi, Yasuomi

2003-01-01

In the plasma flash x-ray generator, a high-voltage main condenser of approximately 200 nF is charged up to 55 kV by a power supply, and electric charges in the condenser are discharged to an x-ray tube after triggering the cathode electrode. The flash x-rays are then produced. The x-ray tube is a demountable triode that is connected to a turbo molecular pump with a pressure of approximately 1 mPa. As electron flows from the cathode electrode are roughly converged to a rod molybdenum target of 2.0 mm in diameter by the electric field in the x-ray tube, weakly ionized linear plasma, which consists of molybdenum ions and electrons, forms by target evaporation. At a charging voltage of 55 kV, the maximum tube voltage was almost equal to the charging voltage of the main condenser, and the peak current was about 20 kA. When the charging voltage was increased, the linear plasma formed, and the K-series characteristic x-ray intensities increased. The K lines were quite sharp and intense, and hardly any bremsstrahlung rays were detected. The x-ray pulse widths were approximately 700 ns, and the time-integrated x-ray intensity had a value of approximately 35 μC/kg at 1.0 m from the x-ray source with a charging voltage of 50 kV. (author)

Experimental platform for investigations of high-intensity laser plasma interactions in the magnetic field of a pulsed power generator

Science.gov (United States)

Ivanov, V. V.; Maximov, A. V.; Swanson, K. J.; Wong, N. L.; Sarkisov, G. S.; Wiewior, P. P.; Astanovitskiy, A. L.; Covington, A. M.

2018-03-01

An experimental platform for the studying of high-intensity laser plasma interactions in strong magnetic fields has been developed based on the 1 MA Zebra pulsed power generator coupled with the 50-TW Leopard laser. The Zebra generator produces 100-300 T longitudinal and transverse magnetic fields with different types of loads. The Leopard laser creates plasma at an intensity of 1019 W/cm2 in the magnetic field of coil loads. Focusing and targeting systems are integrated in the vacuum chamber of the pulsed power generator and protected from the plasma debris and strong mechanical shock. The first experiments with plasma at laser intensity >2 × 1018 W/cm2 demonstrated collimation of the laser produced plasma in the axial magnetic field strength >100 T.

Propagation of intense laser pulses in an underdense plasma

International Nuclear Information System (INIS)

Monot, P.; Auguste, T.; Gibbon, P.; Jakober, F.; Mainfray, G.

1994-01-01

Experiments carried out with a laser beam focused into a vacuum chamber onto a 3-mm long, pulsed hydrogen jet, at powers close to the critical power required for relativistic self focusing, have shown that an underdense plasma is able to significantly reduce the divergence of an intense laser pulse. The propagation mode is in good agreement with theoretical predictions of relativistic self focusing. 2 figs., 8 refs

Ion-beam plasma and propagation of intense compensated ion beams

Energy Technology Data Exchange (ETDEWEB)

Gabovich, M D [AN Ukrainskoj SSR, Kiev. Inst. Fiziki

1977-02-01

Discussed are the results of investigation of plasma properties received by neutralization of intense ion beam space charge. Considered is the process of ion beam compensation by charges, formed as a result of gas ionization by this beam or by externally introduced ones. Emphasis is placed on collective phenomena in ion-beam plasma, in particular on non-linear effects limiting amplitude of oscillations. It is shown that not only dynamic decompensation but the Coulomb collisions of ions with electrons as well as other collective oscillations significantly affects the propagation of compensated ion beams. All the processes are to be taken into account in solving the problem of obtaining ''superdense'' compensated beams.

Ion-beam plasma and propagation of intense compensated ion beams

International Nuclear Information System (INIS)

Gabovich, M.D.

1977-01-01

Discussed are the results of investigation of plasma properties recieved by neutralization of intensive ion beam space charge. Considered is the process of ion beam compensation by charges, formed as a result of gas ionization by this beam or by externally introduced ones. Emphasis is placed on collective phenomena in ion-beam plasma, in particular on non-linear effects limiting amplitude of oscillations. It is shown, that not only dinamic decompensation but the Coulomb collisions of ions with electrons as well as other collective oscillations significantly affects the propagation of compensated ion beams. All the processes are to be taken into account at solving the problem of obtaining ''superdense'' compensated beams

Benefits of oxygen and nitrogen plasma treatment in Vero cell affinity to poly(lactide-co-glycolide acid

Directory of Open Access Journals (Sweden)

Andrea Rodrigues Esposito

2013-01-01

Full Text Available Cell adhesion on materials surface is critical because this phenomenon occurs before other events, as cell spreading, cell migration and cell differentiation. it is commonly accepted that the adhesion of cells on solid substrate is influenced by several substratum surface properties, such as wettability, surface charge, roughness and topography. plasma technique is a convenient method for modifying surface properties of materials without affecting physical properties. in this study, poly(lactide-co-glycolide, plga, membranes were modified by oxygen and nitrogen plasma to improve polymer hydrophilicity and verify their effect on vero cells culture. the plga membranes, which were characterized by sem and contact angle, showed increased surface rugosity and narrower contact angles. cell adhesion, cytotoxicity assay, sem and cytochemistry analysis showed that plasma treatment was beneficial to cell growth by improving cell-polymer interaction. Cell adhesion on materials surface is critical because this phenomenon occurs before other events, as cell spreading, cell migration and cell differentiation. It is commonly accepted that the adhesion of cells on solid substrate is influenced by several substratum surface properties, such as wettability, surface charge, roughness and topography. Plasma technique is a convenient method for modifying surface properties of materials without affecting physical properties. In this study, poly(lactide-co-glycolide, PLGA, membranes were modified by oxygen and nitrogen plasma to improve polymer hydrophilicity and verify their effect on Vero cells culture. The PLGA membranes, which were characterized by SEM and contact angle, showed increased surface rugosity and narrower contact angles. Cell adhesion, cytotoxicity assay, SEM and cytochemistry analysis showed that plasma treatment was beneficial to cell growth by improving cell-polymer interaction.

Dynamics of triacylglycerol and EPA production in Phaeodactylum tricornutum under nitrogen starvation at different light intensities.

Directory of Open Access Journals (Sweden)

Ilse M Remmers

Full Text Available Lipid production in microalgae is highly dependent on the applied light intensity. However, for the EPA producing model-diatom Phaeodactylum tricornutum, clear consensus on the impact of incident light intensity on lipid productivity is still lacking. This study quantifies the impact of different incident light intensities on the biomass, TAG and EPA yield on light in nitrogen starved batch cultures of P. tricornutum. The maximum biomass concentration and maximum TAG and EPA contents were found to be independent of the applied light intensity. The lipid yield on light was reduced at elevated light intensities (>100 μmol m-2 s-1. The highest TAG yield on light (112 mg TAG molph-1 was found at the lowest light intensity tested (60 μmol m-2 s-1, which is still relatively low to values reported in literature for other algae. Furthermore, mass balance analysis showed that the EPA fraction in TAG may originate from photosynthetic membrane lipids.

Nuclear Fusion Effects Induced in Intense Laser-Generated Plasmas

Directory of Open Access Journals (Sweden)

Lorenzo Torrisi

2013-01-01

Full Text Available Deutered polyethylene (CD2n thin and thick targets were irradiated in high vacuum by infrared laser pulses at 1015W/cm2 intensity. The high laser energy transferred to the polymer generates plasma, expanding in vacuum at supersonic velocity, accelerating hydrogen and carbon ions. Deuterium ions at kinetic energies above 4 MeV have been measured by using ion collectors and SiC detectors in time-of-flight configuration. At these energies the deuterium–deuterium collisions may induce over threshold fusion effects, in agreement with the high D-D cross-section valuesaround 3 MeV energy. At the first instants of the plasma generation, during which high temperature, density and ionacceleration occur, the D-D fusions occur as confirmed by the detection of mono-energetic protonsand neutrons with a kinetic energy of 3.0 MeV and 2.5 MeV, respectively, produced by the nuclear reaction. The number of fusion events depends strongly on the experimental set-up, i.e. on the laser parameters (intensity, wavelength, focal spot dimension, target conditions (thickness, chemical composition, absorption coefficient, presence of secondary targets and used geometry (incidence angle, laser spot, secondary target positions.A number of D-D fusion events of the order of 106÷7 per laser shot has been measured.

Ultra-intense, short pulse laser-plasma interactions with applications to the fast ignitor

International Nuclear Information System (INIS)

Wilks, S.C.; Kruer, W.L.; Young, P.E.; Hammer, J.; Tabak, M.

1995-04-01

Due to the advent of chirped pulse amplification (CPA) as an efficient means of creating ultra-high intensity laser light (I > 5x10 17 W/cm 2 ) in pulses less than a few picoseconds, new ideas for achieving ignition and gain in DT targets with less than 1 megajoule of input energy are currently being pursued. Two types of powerful lasers are employed in this scheme: (1) channeling beams and (2) ignition beams. The current state of laser-plasma interactions relating to this fusion scheme will be discussed. In particular, plasma physics issues in the ultra-intense regime are crucial to the success of this scheme. We compare simulation and experimental results in this highly nonlinear regime

Control of ion content and nitrogen species using a mixed chemistry plasma for GaN grown at extremely high growth rates >9 μm/h by plasma-assisted molecular beam epitaxy

Energy Technology Data Exchange (ETDEWEB)

Gunning, Brendan P.; Clinton, Evan A.; Merola, Joseph J.; Doolittle, W. Alan, E-mail: alan.doolittle@ece.gatech.edu [Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); Bresnahan, Rich C. [Veeco Instruments, St. Paul, Minnesota 55127 (United States)

2015-10-21

Utilizing a modified nitrogen plasma source, plasma assisted molecular beam epitaxy (PAMBE) has been used to achieve higher growth rates in GaN. A higher conductance aperture plate, combined with higher nitrogen flow and added pumping capacity, resulted in dramatically increased growth rates up to 8.4 μm/h using 34 sccm of N{sub 2} while still maintaining acceptably low operating pressure. It was further discovered that argon could be added to the plasma gas to enhance growth rates up to 9.8 μm/h, which was achieved using 20 sccm of N{sub 2} and 7.7 sccm Ar flows at 600 W radio frequency power, for which the standard deviation of thickness was just 2% over a full 2 in. diameter wafer. A remote Langmuir style probe employing the flux gauge was used to indirectly measure the relative ion content in the plasma. The use of argon dilution at low plasma pressures resulted in a dramatic reduction of the plasma ion current by more than half, while high plasma pressures suppressed ion content regardless of plasma gas chemistry. Moreover, different trends are apparent for the molecular and atomic nitrogen species generated by varying pressure and nitrogen composition in the plasma. Argon dilution resulted in nearly an order of magnitude achievable growth rate range from 1 μm/h to nearly 10 μm/h. Even for films grown at more than 6 μm/h, the surface morphology remained smooth showing clear atomic steps with root mean square roughness less than 1 nm. Due to the low vapor pressure of Si, Ge was explored as an alternative n-type dopant for high growth rate applications. Electron concentrations from 2.2 × 10{sup 16} to 3.8 × 10{sup 19} cm{sup −3} were achieved in GaN using Ge doping, and unintentionally doped GaN films exhibited low background electron concentrations of just 1–2 × 10{sup 15} cm{sup −3}. The highest growth rates resulted in macroscopic surface features due to Ga cell spitting, which is an engineering challenge still to be

Control of ion content and nitrogen species using a mixed chemistry plasma for GaN grown at extremely high growth rates >9 μm/h by plasma-assisted molecular beam epitaxy

International Nuclear Information System (INIS)

Gunning, Brendan P.; Clinton, Evan A.; Merola, Joseph J.; Doolittle, W. Alan; Bresnahan, Rich C.

2015-01-01

Utilizing a modified nitrogen plasma source, plasma assisted molecular beam epitaxy (PAMBE) has been used to achieve higher growth rates in GaN. A higher conductance aperture plate, combined with higher nitrogen flow and added pumping capacity, resulted in dramatically increased growth rates up to 8.4 μm/h using 34 sccm of N 2 while still maintaining acceptably low operating pressure. It was further discovered that argon could be added to the plasma gas to enhance growth rates up to 9.8 μm/h, which was achieved using 20 sccm of N 2 and 7.7 sccm Ar flows at 600 W radio frequency power, for which the standard deviation of thickness was just 2% over a full 2 in. diameter wafer. A remote Langmuir style probe employing the flux gauge was used to indirectly measure the relative ion content in the plasma. The use of argon dilution at low plasma pressures resulted in a dramatic reduction of the plasma ion current by more than half, while high plasma pressures suppressed ion content regardless of plasma gas chemistry. Moreover, different trends are apparent for the molecular and atomic nitrogen species generated by varying pressure and nitrogen composition in the plasma. Argon dilution resulted in nearly an order of magnitude achievable growth rate range from 1 μm/h to nearly 10 μm/h. Even for films grown at more than 6 μm/h, the surface morphology remained smooth showing clear atomic steps with root mean square roughness less than 1 nm. Due to the low vapor pressure of Si, Ge was explored as an alternative n-type dopant for high growth rate applications. Electron concentrations from 2.2 × 10 16 to 3.8 × 10 19 cm −3 were achieved in GaN using Ge doping, and unintentionally doped GaN films exhibited low background electron concentrations of just 1–2 × 10 15 cm −3 . The highest growth rates resulted in macroscopic surface features due to Ga cell spitting, which is an engineering challenge still to be addressed. Nonetheless, the

Temporal evolution of plasma density in femtosecond light filaments

International Nuclear Information System (INIS)

Wang Haitao; Fan Chengyu; Shen Hong; Qiao Chunhong; Zhang Jinghui; Zhang Pengfei; Ma Huimin; Xu Huiling

2012-01-01

By using a legible and comprehensive physical model describing the generation and evolvement of ion densities in the plasma channel induced by intense femtosecond laser pulse, the work studied the temporal evolution of the plasma densities in femtosecond light filaments. It shows that the contribution of the ionization of oxygen and nitrogen molecules to the total electron densities varies much for different laser pulse shapes, and the pulse shapes have more effects on the lifetime of the higher density plasma. It is necessary to control the pulse shape for efficient using of the plasma channel. Pulses of long duration and short wavelength can obtain a plasma channel with higher electron density, but the channel lifetime thoroughly depends on the later evolution of the self-guided channel. (authors)

Intense microwave pulse propagation through gas breakdown plasmas in a waveguide

International Nuclear Information System (INIS)

Byrne, D.P.

1986-01-01

High-power microwave pulse-compression techniques are used to generate 2.856 GHz pulses which are propagated in a TE 10 mode through a gas filled section of waveguide, where the pulses interact with self-generated gas-breakdown plasmas. Pulse envelopes transmitted through the plasmas, with duration varying from 2 ns to greater than 1 μs, and peak powers of a few kW to nearly 100 MW, are measured as a function of incident pulse and gas pressure for air, nitrogen, and helium. In addition, the spatial and temporal development of the optical radiation emitted by the breakdown plasmas are measured. For transmitted pulse durations ≥ 100 ns, good agreement is found with both theory and existing measurements. For transmitted pulse duration as short as 2 ns (less than 10 rf cycles), a two-dimensional model is used in which the electrons in the plasma are treated as a fluid whose interactions with the microwave pulse are governed by a self-consistent set of fluid equations and Maxwell's equations for the electromagnetic field. The predictions of this model for air are compared with the experimental results over a pressure range of 0.8 torr to 300 torr. Good agreement is obtained above about 1 torr pressure, demonstrating that microwave pulse propagation above the breakdown threshold can be accurately modeled on this time scale. 63 refs., 44 figs., 2 tabs

A tesselation-based model for intensity estimation and laser plasma interactions calculations in three dimensions

Science.gov (United States)

Colaïtis, A.; Chapman, T.; Strozzi, D.; Divol, L.; Michel, P.

2018-03-01

A three-dimensional laser propagation model for computation of laser-plasma interactions is presented. It is focused on indirect drive geometries in inertial confinement fusion and formulated for use at large temporal and spatial scales. A modified tesselation-based estimator and a relaxation scheme are used to estimate the intensity distribution in plasma from geometrical optics rays. Comparisons with reference solutions show that this approach is well-suited to reproduce realistic 3D intensity field distributions of beams smoothed by phase plates. It is shown that the method requires a reduced number of rays compared to traditional rigid-scale intensity estimation. Using this field estimator, we have implemented laser refraction, inverse-bremsstrahlung absorption, and steady-state crossed-beam energy transfer with a linear kinetic model in the numerical code Vampire. Probe beam amplification and laser spot shapes are compared with experimental results and pf3d paraxial simulations. These results are promising for the efficient and accurate computation of laser intensity distributions in holhraums, which is of importance for determining the capsule implosion shape and risks of laser-plasma instabilities such as hot electron generation and backscatter in multi-beam configurations.

Yield of Ozone, Nitrite Nitrogen and Hydrogen Peroxide Versus Discharge Parameter Using APPJ Under Water

International Nuclear Information System (INIS)

Chen Bingyan; Wen Wen; Zhu Changping; Wang Yuan; Gao Ying; Fei Juntao; He Xiang; Yin Cheng; Jiang Yongfeng; Chen Longwei

2016-01-01

Discharge plasma in and in contact with water can be accompanied with ultraviolet radiation and electron impact, thus can generate hydroxyl radicals, ozone, nitrite nitrogen and hydrogen peroxide. In this paper, a non-equilibrium plasma processing system was established by means of an atmospheric pressure plasma jet immersed in water. The hydroxyl intensities and discharge energy waveforms were tested. The results show that the positive and negative discharge energy peaks were asymmetric, where the positive discharge energy peak was greater than the negative one. Meanwhile, the yield of ozone and nitrite nitrogen was enhanced with the increase of both the treatment time and the discharge energy. Moreover, the pH value of treated water was reduced rapidly and maintained at a lower level. The residual concentration of hydrogen peroxide in APPJ treated water was kept at a low level. Additionally, both the efficiency energy ratio of the yield of ozone and nitrite nitrogen and that of the removal of p-nitrophenol increased as a function of discharge energy and discharge voltage. The experimental results were fully analyzed and the chemical reaction equations and the physical processes of discharges in water were given. (paper)

[Measurement of plasma parameters in cluster hexagon pattern discharge by optical emission spectrum].

Science.gov (United States)

Dong, Li-Fang; Shen, Zhong-Kai; Li, Xin-Chun; Liu, Liang; Lu, Ning; Shang, Jie

2012-09-01

The cluster hexagon pattern was obtained in a dielectric barrier discharge in air/argon for the first time. Three plasma parameters, i. e. the molecular vibrational temperature, the molecular rotational temperature and the average electron energy of individual cluster in cluster hexagon pattern discharge, were studied by changing the air content. The molecular vibrational temperature and the molecular rotational temperature were calculated using the second positive band system of nitrogen molecules (C 3IIu --> B 3IIg) and the first negative band system of nitrogen molecular ions (B 2Sigma(u)+ --> Chi2 Sigma(g)+). The relative intensities of the first negative system of nitrogen molecular ions (391. 4 nm) and nitrogen molecules emission spectrum line (337.1 nm) were analyzed for studying the variations of the electron energy. It was found that the three plasma parameters of individual cluster in cluster hexagon pattern increase with air content increasing from 16% to 24%.

Plasma streams mixing in two-channel t-shaped magnetic filter

International Nuclear Information System (INIS)

Aksyonov, D.S.; Aksenov, I.I.; Luchaninov, A.A.; Reshetnyak, E.N.; Strel'nitskij, V.E.

2011-01-01

Ti-Al-N films were deposited by vacuum arc method. T-shaped magnetic filter with two channels was used for films preparation. Deposition was performed after aluminum and titanium separate plasma streams from two plasma sources were mixed into single one inside plasma duct having weakened magnetic field near its output. Obtained films have uniform distribution of composition and thickness on 180 mm diameter substrate surface. It was found that mixing and homogenization degree depends on nitrogen pressure, output magnetic field intensity and output- to-substrate distance. Film self-sputtering and aluminum preferential sputtering were observed for elevated negative substrate bias potentials.

Isotope exchange investigation of nitrogen redistribution in expanded austenite

International Nuclear Information System (INIS)

Christiansen, T.L.; Drouet, M.; Martinavičius, A.; Somers, M.A.J.

2013-01-01

Sequential plasma and gaseous nitriding of Fe–18Cr–10Ni–3Mo stainless steel at 390 °C with 14 N and 15 N isotopes followed by denitriding in flowing hydrogen was investigated. Redistribution of plasma-inserted nitrogen atoms ( 15 N) by subsequent gaseous nitriding ( 14 N) was observed. Denitriding after plasma- and gaseous nitriding resulted in predominant retraction of 14 N, and only a minor amount of 15 N. The nitrogen isotope diffusion behaviour is explained by two different states of nitrogen bonding and short-range ordering between nitrogen and chromium

Surface modification by nitrogen plasma immersion ion implantation into new steel 460Li–21Cr in a capacitively coupled radio frequency discharge

International Nuclear Information System (INIS)

Bhuyan, H.; Mändl, S.; Bora, B.; Favre, M.; Wyndham, E.; Maze, J.R.; Walczak, M.; Manova, D.

2014-01-01

Highlights: • Nitriding of a novel steel has been done in a RF plasma by PIII technique. • Improved hardness and wear behavior have been observed. • Hardness was improved by a factor 4 and the wear by 2 orders of magnitude. • Fast, anomalous diffusion, similar to nitrogen in expanded austenite is observed. - Abstract: A novel steel 460Li–21Cr belonging to a new generation of superferritic grade steel has been implanted with nitrogen in a low power 13.56 MHz radio frequency plasma by the plasma immersion ion implantation (PIII) technique in order to study its physical and chemical properties under different experimental conditions. We observed improved hardness and wear behavior of 460Li–21Cr steel with a layer thickness between 1.5 and 4.0 μm after 60 min implantation in the temperature range from 350 to 550 °C. The modified surface layer containing nitrogen does not show CrN in X-ray diffraction (XRD). Compared to untreated substrates, the hardness can be increased by a factor of 4, depending on the experimental conditions, and the wear behavior was also improved by two orders of magnitude. The results are very similar to those for austenitic stainless steel with a similar pronounced increase in wear resistance and plateau-like nitrogen depth profiles

Nitrogen deposition and its contribution to nutrient inputs to intensively managed agricultural ecosystems.

Science.gov (United States)

He, Chun-E; Wang, Xin; Liu, Xuejun; Fangmeier, Andreas; Christie, Peter; Zhang, Fusuo

2010-01-01

Interest in nitrogen inputs via atmospheric deposition to agricultural ecosystems has increased recently, especially on the North China Plain because of extremely intensive agricultural systems and rapid urbanization in this region. Nitrogen deposition may make a significant contribution to crop N requirements but may also impose a considerable nutrient burden on the environment in general. We quantified total N deposition at two locations, Dongbeiwang near Beijing and Quzhou in Hebei province, over a two-year period from 2005 to 2007 using an 15N tracer method, the integrated total N input (ITNI) system. Total airborne N inputs to a maize wheat rotation system at both locations ranged from 99 to 117 kg N x ha(-1) x yr(-1), with higher N deposition during the maize season (57-66 kg N/ha) than the wheat season (42-51 kg N/ha). Plant available N from deposition for maize and wheat was about 52 kg N x ha(-1) x yr(-1), accounting for 50% of the total N deposition or 31% of total N uptake by the two crop species. In addition, a correction factor was derived for the maize season to adjust values obtained from small pots (0.057 m2) compared with field trays (0.98 m2) because of higher plant density in the pots. The results indicate that atmospheric N deposition is a very important N input and must be taken into account when calculating nutrient budgets in very intensively managed agricultural ecosystems.

Ultra-intense, short pulse laser-plasma interactions with applications to the fast ignitor

Energy Technology Data Exchange (ETDEWEB)

Wilks, S.C.; Kruer, W.L.; Young, P.E.; Hammer, J.; Tabak, M.

1995-04-01

Due to the advent of chirped pulse amplification (CPA) as an efficient means of creating ultra-high intensity laser light (I > 5{times}10{sup 17} W/cm{sup 2}) in pulses less than a few picoseconds, new ideas for achieving ignition and gain in DT targets with less than 1 megajoule of input energy are currently being pursued. Two types of powerful lasers are employed in this scheme: (1) channeling beams and (2) ignition beams. The current state of laser-plasma interactions relating to this fusion scheme will be discussed. In particular, plasma physics issues in the ultra-intense regime are crucial to the success of this scheme. We compare simulation and experimental results in this highly nonlinear regime.

Raising the Corrosion Resistance of Low-Carbon Steels by Electrolytic-Plasma Saturation with Nitrogen and Carbon

Science.gov (United States)

Kusmanov, S. A.; Grishina, E. P.; Belkin, P. N.; Kusmanova, Yu. V.; Kudryakova, N. O.

2017-05-01

Structural features of the external oxide layer and internal nitrided, carbonitrided and carburized layers in steels 10, 20 and St3 produced by the method of electrolytic plasma treatment are studied. Specimens of the steels are tested for corrosion in a naturally aerated 1-N solution of sodium chloride. The condition of the metal/sodium chloride solution interface is studied by the method of electrochemical impedance spectroscopy. It is shown that the corrosion resistance of low-carbon steels can be raised by anode electrolytic-plasma saturation with nitrogen and carbon. Recommendations are given on the choice of carbonitriding modes for structural steels.

Nitrogen binding behavior in ZnO films with time-resolved cathodoluminescence

International Nuclear Information System (INIS)

Mei, Y.F.; Fu, Ricky K.Y.; Siu, G.G.; Wong, K.W.; Chu, Paul K.; Wang, R.S.; Ong, H.C.

2006-01-01

ZnO film with (1 0 0) orientation was produced on silicon substrate and doped with nitrogen using plasma immersion ion implantation. The effects due to N doping were investigated using cathodoluminescence (CL). In the heavily nitrogen-doped ZnO film, the intensity of ultraviolet (UV) band decreases and that of the visible band increases as a function of the electron bombardment cycle i.e. time. Based on the X-ray photoelectron spectroscopy (XPS) analysis, the unstable Zn-N bond is responsible for the CL behavior and the experimental results agree well with the first-principle calculation. Our work is helpful to our understanding of the role of p-type dopants in ZnO

Effects induced by high and low intensity laser plasma on SiC Schottky detectors

Directory of Open Access Journals (Sweden)

Sciuto Antonella

2018-01-01

Full Text Available Silicon-Carbide detectors are extensively employed as diagnostic devices in laser-generated plasma, allowing the simultaneous detection of photons, electrons and ions, when used in time-of-flight configuration. The plasma generated by high intensity laser (1016 W/cm2 producing high energy ions was characterized by SiC detector with a continuous front-electrode, and a very thick active depth, while SiC detector with an Interdigit front-electrode was used to measure the low energy ions of plasma generated by low intensity laser (1010 W/cm2. Information about ion energy, number of charge states, plasma temperature can be accurately obtained. However, laser exposure induces the formation of surface and bulk defects whose concentration increases with increasing the time to plasma exposure. The surface defects consist of clusters with a main size of the order of some microns and they modify the diode barrier height and the efficiency of the detector as checked by alpha spectrometry. The bulk defects, due to the energy loss of detected ions, strongly affect the electrical properties of the device, inducing a relevant increase of the leakage (reverse current and decrease the forward current related to a deactivation of the dopant in the active detector region.

Effects induced by high and low intensity laser plasma on SiC Schottky detectors

Science.gov (United States)

Sciuto, Antonella; Torrisi, Lorenzo; Cannavò, Antonino; Mazzillo, Massimo; Calcagno, Lucia

2018-01-01

Silicon-Carbide detectors are extensively employed as diagnostic devices in laser-generated plasma, allowing the simultaneous detection of photons, electrons and ions, when used in time-of-flight configuration. The plasma generated by high intensity laser (1016 W/cm2) producing high energy ions was characterized by SiC detector with a continuous front-electrode, and a very thick active depth, while SiC detector with an Interdigit front-electrode was used to measure the low energy ions of plasma generated by low intensity laser (1010 W/cm2). Information about ion energy, number of charge states, plasma temperature can be accurately obtained. However, laser exposure induces the formation of surface and bulk defects whose concentration increases with increasing the time to plasma exposure. The surface defects consist of clusters with a main size of the order of some microns and they modify the diode barrier height and the efficiency of the detector as checked by alpha spectrometry. The bulk defects, due to the energy loss of detected ions, strongly affect the electrical properties of the device, inducing a relevant increase of the leakage (reverse) current and decrease the forward current related to a deactivation of the dopant in the active detector region.

Plasma uric acid, creatinine, and urea nitrogen concentrations after whole blood administration via the gastrointestinal tract in domestic pigeons (Columba livia).

Science.gov (United States)

Sheldon, Julie; Hoover, John P; Payton, Mark E

2007-06-01

To determine if blood administered to pigeons by gavage tube would simulate gastrointestinal hemorrhage in a noncarnivorous avian model, be digested in the gastrointestinal tract, and subsequently alter concentrations of plasma urea nitrogen, creatinine, or uric acid, blood from common peacocks (Pavo cristatus) was administered by gavage tube to 5 healthy domestic pigeons (Columba livia) at doses of 0.5, 1.0, 2.0, 4.0, and 8.0 ml/kg. No significant difference in plasma concentrations of urea nitrogen, creatinine, or uric acid was seen 4-6 hours after gavage. The findings did not support or rule out the presence of gastrointestinal blood in pigeons as a model for hemorrhage in noncarnivorous avian species.

Control over the morphology of AlN during molecular beam epitaxy with the plasma activation of nitrogen on Si (111) substrates

International Nuclear Information System (INIS)

Mizerov, A. M.; Kladko, P. N.; Nikitina, E. V.; Egorov, A. Yu.

2015-01-01

The results of studies of the growth kinetics of AlN layers during molecular beam epitaxy with the plasma activation of nitrogen using Si (111) substrates are presented. The possibility of the growth of individual AlN/Si (111) nanocolumns using growth conditions with enrichment of the surface with metal near the formation mode of Al drops, at a substrate temperature close to maximal, during molecular beam epitaxy with the plasma activation of nitrogen (T s ≈ 850°C) is shown. The possibility of growing smooth AlN layers on a nanocolumnar AlN/Si (111) buffer with the use of T s ≈ 750°C and growth conditions providing enrichment with metal is shown

Control over the morphology of AlN during molecular beam epitaxy with the plasma activation of nitrogen on Si (111) substrates

Energy Technology Data Exchange (ETDEWEB)

Mizerov, A. M., E-mail: mizerov@beam.ioffe.ru; Kladko, P. N.; Nikitina, E. V.; Egorov, A. Yu. [Russian Academy of Sciences, St. Petersburg Academic University-Nanotechnology Research and Education Centre (Russian Federation)

2015-02-15

The results of studies of the growth kinetics of AlN layers during molecular beam epitaxy with the plasma activation of nitrogen using Si (111) substrates are presented. The possibility of the growth of individual AlN/Si (111) nanocolumns using growth conditions with enrichment of the surface with metal near the formation mode of Al drops, at a substrate temperature close to maximal, during molecular beam epitaxy with the plasma activation of nitrogen (T{sub s} ≈ 850°C) is shown. The possibility of growing smooth AlN layers on a nanocolumnar AlN/Si (111) buffer with the use of T{sub s} ≈ 750°C and growth conditions providing enrichment with metal is shown.

A stable production of intense electron beam plasma with ion back stream

International Nuclear Information System (INIS)

Uramoto, Johshin.

1975-12-01

An intense electron beam is extracted without space charge limit from a dc plasma source along a magnetic field. The beam space charge is neutralized stably through back streaming of self-ionized ions from the beam extracting anode region where a neutral gas is fed locally. In Appendix I, a space charge free electron gun is designed under this neutralization method. In Appendix II, a dynamic discharge through a series resistance is described, where an operative mechanism of the well-known TP-D plasma is clarified. (auth.)

Effect of Low-Pressure Nitrogen DC Plasma Treatment on the Surface Properties of Biaxially Oriented Polypropylene, Poly (Methyl Methacrylate) and Polyvinyl Chloride Films

International Nuclear Information System (INIS)

Mortazavi, S. Hamideh; Ghoranneviss, Mahmood; Pilehvar, Soheil; Esmaeili, Sina; Zargham, Shamim; Hashemi, S. Ebrahim; Jodat, Hamzeh

2013-01-01

In this study, commercial biaxially oriented polypropylene (BOPP), polyvinyl chloride (PVC) and poly (methyl methacrylate) (PMMA) films were treated with nitrogen plasma over different exposure times in a Pyrex tube surrounded by a DC variable magnetic field. The chemical changes that appeared on the surface of the samples were investigated using Fourier transform infrared (FT-IR) spectroscopy and attenuated total reflectance Fourier transform infrared (ATR-FTIR) spectroscopy after treatment for 2 min, 4 min and 6 min in a nitrogen plasma chamber. Effects of the plasma treatment on the surface topographies and contact angles of the untreated and plasma treated films were also analyzed by atomic force microscopy (AFM) and a contact angle measuring system. The results show that the plasma treated films become more hydrophilic with an enhanced wettability due to the formation of some new polar groups on the surface of the treated films. Moreover, at higher exposure times, the total surface energy in all treated films increased while a reduction in contact angle occurred. The behavior of surface roughness in each sample was completely different at higher exposure times. (plasma technology)

Correlation Between Protein Intake and Nitrogen Balance of Surgical Patients in Anesthesiology and Intensive Care Installation, Sanglah General Hospital, Denpasar, Bali, Indonesia

Directory of Open Access Journals (Sweden)

Made Wiryana

2016-06-01

Full Text Available Background: A cell injury from surgical stress in a trauma or a non-trauma case will induce a hyper metabolic response in which the protein degradation increases, the somatic protein synthesis decreases and the amino acid catabolism increases. Thus, the pyper metabolic response contributes to nitrogen loss in urine. This response, without an adequate nutrition, will lead an iatrogenic malnutrition and deterioration. A balance nitrogen formula through urinary urea nitrogen is one of many nutrition evaluation methods. This method aids in evaluating the daily nutrition status and it can be the baseline data for daily intake. Objective: To find a correlation between the protein intake and the nitrogen balance of the surgical patients in anesthesiology and intensive care installation, Sanglah General Hospital, Denpasar, Bali. Methods: Fifty-one surgical patients with trauma and non-trauma cases were observed for their protein intake for 2-3 days continuously. Moreover, they were evaluated for their nitrogen balance based on the urinary urea nitrogen per 24 hours for 2-3 days. For statistical analysis, we utilized Shapiro-Francia, Shapiro-Wilk, Spearman Frank correlation, two-sample t test, and multivariate regression analysis in Strata SE 12.1. Results: The correlation between the protein intake and the nitrogen balance on the first day was ra=0.50 (p<0.05, on the second day ra=0.70 (p<0,05, and on the third day ra=0.740 (p<0,05. Conclusions: There is a correlation between the protein intake and the nitrogen balance of surgical patients in Anesthesiology and Intensive Care Installation Sanglah General Hospital Denpasar. 

High-intensity laser for Ta and Ag implantation into different substrates for plasma diagnostics

Energy Technology Data Exchange (ETDEWEB)

Cutroneo, M., E-mail: cutroneo@ujf.cas.cz [Nuclear Physics Institute, AS CR, 25068 Rez (Czech Republic); Mackova, A.; Malinsky, P. [Nuclear Physics Institute, AS CR, 25068 Rez (Czech Republic); Department of Physics, Faculty of Science, J.E. Purkinje University, Ceske mladeze 8, 400 96 Usti nad Labem (Czech Republic); Matousek, J. [Department of Physics, Faculty of Science, J.E. Purkinje University, Ceske mladeze 8, 400 96 Usti nad Labem (Czech Republic); Torrisi, L. [Department of Physics and Earth Sciences, Messina University, V.le F.S. d’Alcontres 31, 98166 S. Agata, Messina (Italy); Ullschmied, J. [Institute of Physics, ASCR, v.v.i., 182 21 Prague 8 (Czech Republic)

2015-07-01

High-intensity lasers generating non-equilibrium plasma, can be employed to accelerate ions in the keV–MeV region, useful for many applications. In the present work, we performed study of ion implantation into different substrates by using a high-intensity laser at the PALS laboratory in Prague. Multi-energy ions generated by plasma from Ta and Ag targets were implanted into polyethylene and metallic substrates (Al, Ti) at energies of tens of keV per charge state. The ion emission was monitored online using time-of-flight detectors and electromagnetic deflection systems. Rutherford Backscattering Spectrometry (RBS) was used to characterise the elemental composition in the implanted substrates by ion plasma emission and to provide the implanted ion depth profiling. These last measurements enable offline plasma characterisation and provide information on the useful potentiality of multi-ion species and multi-energy ion implantation into different substrates. XPS analysis gives information on the chemical bonds and their modifications in the first superficial implanted layers. The depth distributions of implanted Ta and Ag ions were compared with the theoretical ones achieved by using the SRIM-2012 simulation code.

Target Surface Area Effects on Hot Electron Dynamics from High Intensity Laser-Plasma Interactions

Science.gov (United States)

2016-08-19

Science, University ofMichigan, AnnArbor,MI 48109-2099, USA E-mail: czulick@umich.edu Keywords: laser- plasma ,mass-limited, fast electrons , sheath...New J. Phys. 18 (2016) 063020 doi:10.1088/1367-2630/18/6/063020 PAPER Target surface area effects on hot electron dynamics from high intensity laser... plasma interactions CZulick, ARaymond,AMcKelvey, VChvykov, AMaksimchuk, AGRThomas, LWillingale, VYanovsky andKKrushelnick Center forUltrafast Optical

Angular distributions of plasma edge velocity and integrated intensity: Update on specific impulse for Ablative Laser Propulsion

Science.gov (United States)

Lin, Jun; Pakhomov, Andrew V.

2005-04-01

This work concludes our discussion of the image processing technique developed earlier for determination of specific impulse (Isp) for Ablative Laser Propulsion (ALP). The plasma plumes are recorded with a time-resolved intensified charge-coupled device (ICCD) camera. The plasma was formed in vacuum (˜ 3×10-3 Torr) by focusing output pulses of a laser system (100-ps pulsewidth at 532 nm wavelength and ˜35 mJ energy) on surfaces of C (graphite), Al, Si, Fe, Cu, Zn, Sn, and Pb elements. Angular profiles for integrated intensity and plasma expansion velocity were determined for the tested elements. Such profiles were used further for assessment of specific impulse. Specific impulses derived from angular distributions of plasma expansion velocity and integral intensity appeared in excellent agreement with the data derived earlier from force measurements.

Angular distributions of plasma edge velocity and integrated intensity: Update on specific impulse for Ablative Laser Propulsion

International Nuclear Information System (INIS)

Lin Jun; Pakhomov, Andrew V.

2005-01-01

This work concludes our discussion of the image processing technique developed earlier for determination of specific impulse (Isp) for Ablative Laser Propulsion (ALP). The plasma plumes are recorded with a time-resolved intensified charge-coupled device (ICCD) camera. The plasma was formed in vacuum (∼ 3x10-3 Torr) by focusing output pulses of a laser system (100-ps pulsewidth at 532 nm wavelength and ∼35 mJ energy) on surfaces of C (graphite), Al, Si, Fe, Cu, Zn, Sn, and Pb elements. Angular profiles for integrated intensity and plasma expansion velocity were determined for the tested elements. Such profiles were used further for assessment of specific impulse. Specific impulses derived from angular distributions of plasma expansion velocity and integral intensity appeared in excellent agreement with the data derived earlier from force measurements

Expansion of a nitrogen discharge by sound

International Nuclear Information System (INIS)

Antinyan, M.A.; Galechyan, G.A.; Tavakalyan, L.B.

1992-01-01

When the background pressure and the discharge current in a gas discharge are raised the plasma column is tightened up into a filament. Then the discharge occupies a region of the discharge tube whose transverse dimensions are substantially less than those of the tube. This contraction phenomenon in discharges restricts the range of parameters used in various devices to the range of relatively low discharge currents and low gas pressures. This contraction interferes with creating high-power gas lasers, since it acts destructively on the lasing process. In order to suppress filamentation of discharges the working gas has been pumped through the system at high speed, with considerable success. The turbulent mixing in the stream plays an important role in creating an uncontracted discharge at high pressures. The purpose of the present work is to study the possibility of undoing the contraction of a nitrogen discharge, which is one of the main components in the operation of a CO 2 laser, by introducing an intense sound wave in the discharge tube. Discharge contraction and the effect of a sound wave propagating along the plasma column have been investigated experimentally in nitrogen by studying the current-voltage characteristics of a contracted discharge. 6 refs., 3 figs

Observation of intense beam in low pressure from IPR Plasma Focus facility

International Nuclear Information System (INIS)

Kumar, R.; Shyam, A.; Chaturvedi, S.; Lathi, D.; Sarkar, Partha; Chaudhari, V.; Verma, R.; Shukla, R.; Debnath, K.; Sonara, J.; Shah, K.; Adhikary, B.

2004-01-01

Full text: Plasma focus (PF) is a powerful source of various ionizing radiation such as charged particles beam (ions and electrons), X-ray, neutrons etc. This device can operate from energy level of 50J to 1MJ. Plasma Focus is relatively small, simple and cheap in comparison with other radiation sources based on isotopes, accelerators and fusion reactors. Radiation pulse from PF is strong and very short. Now with the new pulsed power technology this device can be operated repeatedly with enhanced lifetime. All these features make plasma focus a versatile device for academic as well as industrial interest such as hot plasma physics and plasma collective processes, equation of state of matter under extreme conditions, material science including material characterization, dynamic equation control, and surface modification and destruction test. Intense burst of neutrons have been observed from a low energy (3.6 kJ) Mather type plasma focus device operated in 0.4 Torr pressure of deuterium medium at IPR. The emitted neutrons (10 9 /shot), that are accompanied by a strong hard X-ray pulse, were found to be having energy up to 3.26 MeV in the axial direction of the device

Does high intensity exercise affects irisin plasma levels in hemodialysis patients? A pilot study

Directory of Open Access Journals (Sweden)

Marta Gormicho Boavida Marques Esgalhado

2018-04-01

Full Text Available ABSTRACT Background: Irisin is a recently identified exercise-induced hormone that stimulates the "browning" of the white adipose tissue, at least in mice. In chronic kidney disease (CKD patients, irisin regulation is not fully understood, and little attention has been given to the effects of exercise on irisin levels in these patients. The purpose of this study was to assess the effects of high intensity exercise on irisin plasma levels in CKD patients under hemodialysis (HD. Methods: Fifteen HD patients (5 men, 44.4 ± 15.1 years old were studied and served as their own controls. High intensity (single session intradialytic strength exercises consisted of three sets of ten repetitions with four different movements in both lower limbs during 30 minutes. Blood samples were collected on different days (exercise and non-exercise day at exactly the same time (30 and 60 minutes after the start of dialysis session. Plasma irisin levels were measured by ELISA assay and anthropometric and biochemical parameters were evaluated. Results: Irisin plasma levels were significantly reduced in both exercise day (125.0 ± 18.5 to 117.4 ± 15.0 ng/mL, p=0.02 and non-exercise day (121.5 ± 13.7 to 115.4 ± 17.2 ng/mL, p=0.02 after 60 minutes of dialysis. Conclusion: These data suggest that intense intradialytic strength exercise was unable to increase the circulating concentration of irisin in HD patients. Moreover, our data show that after one hour of dialysis session, irisin plasma levels may be reduced.

Study on intense relativistic electron beam propagation in a low density collisionless plasma

International Nuclear Information System (INIS)

Korenev, S.A.; Rubin, N.B.; Khodataev, K.V.

1982-01-01

The results of investigations into the increase in effectivity of transport of an intensive relativistic electron beam (IREB) in a collisionless plasma of low density are presented. The electron beam with the current of 1.5 kA, energy of 300 keV, radius of 1.5 cm is in ected into a plasma channel 180 cm long which is a metallic cylinder covered with a biniplast layer from inside 0.5 cm thickness on which there is a metallic net from the vacuum side. Plasma production is carried out during the supply of voltage pulse to the net. A condition of the optimum IREB distribution is found. It is sohwn that self-focusing IREB transport in plasma of low density can be effective if equilibrium conditions are carried out in plasma with the concentration of electrons less (or equal) to the concentration of electrons in a beam

Spectroscopic properties of nitrogen doped hydrogenated amorphous carbon films grown by radio frequency plasma-enhanced chemical vapor deposition

International Nuclear Information System (INIS)

Hayashi, Y.; Yu, G.; Rahman, M. M.; Krishna, K. M.; Soga, T.; Jimbo, T.; Umeno, M.

2001-01-01

Nitrogen doped hydrogenated amorphous carbon thin films have been deposited by rf plasma-enhanced chemical vapor deposition using CH 4 as the source of carbon and with different nitrogen flow rates (N 2 /CH 4 gas ratios between 0 and 3), at 300 K. The dependence modifications of the optical and the structural properties on nitrogen incorporation were investigated using different spectroscopic techniques, such as, Raman spectroscopy, Fourier transform infrared spectroscopy, x-ray photoelectron spectroscopy, ultraviolet-visible (UV-VIS) spectroscopy, electron spin resonance (ESR), photoluminescence (PL) and spectroscopic ellipsometry (SE). Raman spectroscopy and IR absorption reveal an increase in sp 2 -bonded carbon or a change in sp 2 domain size with increasing nitrogen flow rate. It is found that the configuration of nitrogen atoms incorporated into an amorphous carbon network gradually changes from nitrogen atoms surrounded by three (σ bonded) to two (π bonded) neighboring carbons with increasing nitrogen flow rate. Tauc optical gap is reduced from 2.6 to 2.0 eV, and the ESR spin density and the peak-to-peak linewidth increase sharply with increasing nitrogen flow rate. Excellent agreement has been found between the measured SE data and modeled spectra, in which an empirical dielectric function of amorphous materials and a linear void distribution along the thickness have been assumed. The influence of nitrogen on the electronic density of states is explained based on the optical properties measured by UV-VIS and PL including nitrogen lone pair band. [copyright] 2001 American Institute of Physics

A Revival of Waste: Atmospheric Pressure Nitrogen Plasma Jet Enhanced Jumbo Silicon/Silicon Carbide Composite in Lithium Ion Batteries.

Science.gov (United States)

Chen, Bing-Hong; Chuang, Shang-I; Liu, Wei-Ren; Duh, Jenq-Gong

2015-12-30

In this study, a jumbo silicon/silicon carbide (Si/SiC) composite (JSC), a novel anode material source, was extracted from solar power industry cutting waste and used as a material for lithium-ion batteries (LIBs), instead of manufacturing the nanolized-Si. Unlike previous methods used for preventing volume expansion and solid electrolyte interphase (SEI), the approach proposed here simply entails applying surface modification to JSC-based electrodes by using nitrogen-atmospheric pressure plasma jet (N-APPJ) treatment process. Surface organic bonds were rearranged and N-doped compounds were formed on the electrodes through applying different plasma treatment durations, and the qualitative examinations of before/after plasma treatment were identified by X-ray photoelectron spectroscopy (XPS) and electron probe microanalyzer (EPMA). The surface modification resulted in the enhancement of electrochemical performance with stable capacity retention and high Coulombic efficiency. In addition, depth profile and scanning electron microscope (SEM) images were executed to determine the existence of Li-N matrix and how the nitrogen compounds change the surface conditions of the electrodes. The N-APPJ-induced rapid surface modification is a major breakthrough for processing recycled waste that can serve as anode materials for next-generation high-performance LIBs.

Effect of nitrogen plasma treatment at the Al2O3/Fe interface in magnetic tunnel junction

International Nuclear Information System (INIS)

Shim, Heejae; Cho, B. K.; Kim, Jin-Tae; Kim, T. W.; Park, W. J.

2003-01-01

We investigated the effects of nitrogen plasma treatment on top surface of Fe pinned layer for short times (t ex =0, 10, 30, and 60 s) in magnetic tunnel junctions and annealing of the junctions. The nitrogen-treated junctions show much reduced magnetoresistance (MR) ratio and significantly lower resistance-area (RA) products compared with the untreated junction, i.e., MR≅3%, RA≅30 kΩ μm 2 for t ex =10 s and MR≅10%, RA≅60 kΩ μm 2 for t ex =0 s. The untreated junction showed enhanced MR ratio up to about 17% and higher RA (≅70 kΩ μm2) upon thermal annealing at T a =230 deg. C, as expected. For the nitrogen-treated junctions, while the MR ratio also increases up to about 16% upon annealing at T a =230 deg. C, which is almost the same value as the one of the optimal reference junction, the RA values of the annealed junctions still keep as low as their initial values. We believe that the redistribution of nitrogen during the annealing process is responsible for the change of properties of nitrogen-treated junction. The bias dependence of MR and the estimation of effective barrier height and thickness are studied and found to be consistent with the observed changes in nitrogen-treated junctions

Oxygen and nitrogen plasma etching of three-dimensional hydroxyapatite/chitosan scaffolds fabricated by additive manufacturing

Science.gov (United States)

Myung, Sung-Woon; Kim, Byung-Hoon

2016-01-01

Three-dimensional (3D) chitosan and hydroxyapatite (HAp)/chitosan (CH) scaffolds were fabricated by additive manufacturing, then their surfaces were etched with oxygen (O2) and nitrogen (N2) plasma. O2 and N2 plasma etching was performed to increase surface properties such as hydrophilicity, roughness, and surface chemistry on the scaffolds. After etching, hydroxyapatite was exposed on the surface of 3D HAp/CH scaffolds. The surface morphology and chemical properties were characterized by contact angle measurement, scanning electron microscopy, X-ray diffraction, and attenuated total reflection Fourier infrared spectroscopy. The cell viability of 3D chitosan scaffolds was examined by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay. The differentiation of preosteoblast cells was evaluated by alkaline phosphatase assay. The cell viability was improved by O2 and N2 plasma etching of 3D chitosan scaffolds. The present fabrication process for 3D scaffolds might be applied to a potential tool for preparing biocompatible scaffolds.

Manipulation of the polarization of intense laser beams via optical wave mixing in plasmas

Science.gov (United States)

Michel, Pierre; Divol, Laurent; Turnbull, David; Moody, John

2014-10-01

When intense laser beams overlap in plasmas, the refractive index modulation created by the beat wave via the ponderomotive force can lead to optical wave mixing phenomena reminiscent of those used in crystals and photorefractive materials. Using a vector analysis, we present a full analytical description of the modification of the polarization state of laser beams crossing at arbitrary angles in a plasma. We show that plasmas can be used to provide full control of the polarization state of a laser beam, and give simple analytical estimates and practical considerations for the design of novel photonics devices such as plasma polarizers and plasma waveplates. This work was performed under the auspices of the U.S. Department of Energy by Lawrence Livermore National Laboratory under Contract No. DE-AC52-07NA27344.

On the control of filamentation of intense laser beams propagating in underdense plasma

International Nuclear Information System (INIS)

Williams, E.A.

2006-01-01

In indirect drive inertial confinement fusion ignition designs, the laser energy is delivered into the hohlraum through the laser entrance holes (LEHs), which are sized as small as practicable to minimize x-ray radiation losses. On the other hand, deleterious laser plasma processes, such as filamentation and stimulated backscatter, typically increase with laser intensity. Ideally, therefore, the laser spot shape should be a close fit to the LEH, with uniform (envelope) intensity in the spot and minimal energy at larger radii spilling onto the LEH material. This keeps the laser intensity as low as possible, consistent with the area of the LEH aperture and the power requirements of the design. This can be achieved (at least for apertures significantly larger than the laser's aberrated focal spot) by the use of custom-designed phase plates. However, outfitting the 192-beam National Ignition Facility [J. A. Paisner, E. M. Campbell, and W. J. Hogan, Fusion Tech. 26, 755 1994)] laser with multiple sets of phase plates optimized for a variety of different LEH aperture sizes is an expensive proposition. It is thus important to assess the impact on laser-plasma interaction processes of using phase plates with a smaller than optimum focal spot (or even no phase plates at all!) and then defocusing the beam to expand it to fill the LEH and lower its intensity. Significant effects are found from changes in the characteristic sizes of the laser speckle, from the lack of uniformity of the laser envelope out of the focal plane and on the efficacy of additional polarization smoothing and/or smoothing by spectral dispersion (SSD). These effects are quantified with analytic estimates and simulations using PF3D, our laser-plasma interaction code

Guiding of short, intense laser pulses through solid guides and preformed plasma channels

International Nuclear Information System (INIS)

Borghesi, M.; Mackinnon, A.J.; Gaillard, R.; Malka, G.; Vickers, C.; Willi, O.; Blanchot, N.; Miquel, J.L.; Canaud, B.; Davies, J.R.; Malka, G.; Offenberger, A.A.

2000-01-01

In a series of experiments carried out at the Rutherford Appleton Laboratory, Chilton (UK) and at the Commissariat a l'Energie Atomique, Limeil (France), various techniques of guiding ultra-intense laser pulses over distances exceeding the natural diffraction length were investigated. Efficient guiding was demonstrated both through density channels formed in an underdense plasma by an intense prepulse and through solid guides (hollow capillary tubes). Indication of collimated fast electron propagation though solid targets has also been obtained. (authors)

Propagation of an intense laser pulse in an under-dense plasma: channeling and stimulated Raman scattering

International Nuclear Information System (INIS)

Friou, A.

2012-01-01

This thesis is divided in two parts: i) the laser channeling in hundreds of microns long under-dense plasmas (0.1 nc ≤ n ≤ nc, nc being the critical density) of a laser pulse of intensity 10 18-20 W/cm 2 and duration 1-10 ps; ii) the saturation mechanisms of stimulated Raman back-scattering of a laser pulse of intensity 10 14 to 10 16 W/cm 2 and duration of about 1 ps. A parametric study was performed to study the channeling of a very intense laser pulse, using a 2D PIC (Particle In Cell) code. Various kinds of channels were obtained depending on the laser and plasma parameters, thereby reproducing and enlarging previous studies. Moreover, the channeling velocity was measured and scaling laws were established for homogeneous plasmas. They are then applied to inhomogeneous plasmas, similar to those encountered in inertial confinement fusion (ICF). It is then possible to estimate the energy necessary to channel to the critical density, an important step for the fast ignition scheme of ICF. Raman saturation was studied using numerical simulations, in order to determine if it is due to dephasing or to the growth of sidebands, using different approaches. The first is to study Raman simulations (electromagnetic) performed with kinetic PIC and Vlasov codes. The second, is to study the evolution of a plasma initialized with a distribution function after the adiabatic theory, using a Vlasov code (electrostatic). In this case, we observe the growth of a sideband, with dominant wave number and growth rate in good agreement with kinetic simulations. The saturation of the plasma wave can be caused by both saturation mechanisms. [fr

Langmuir probe diagnostics of an atmospheric pressure, vortex-stabilized nitrogen plasma jet

Energy Technology Data Exchange (ETDEWEB)

Prevosto, L.; Mancinelli, B. R. [Grupo de Descargas Electricas, Departamento Ingenieria Electromecanica, Facultad Regional Venado Tuerto (UTN), Laprida 651, (2600) Venado Tuerto, Santa Fe (Argentina); Kelly, H. [Grupo de Descargas Electricas, Departamento Ingenieria Electromecanica, Facultad Regional Venado Tuerto (UTN), Laprida 651, (2600) Venado Tuerto, Santa Fe (Argentina) and Instituto de Fisica del Plasma (CONICET), Departamento de Fisica, Facultad de Ciencias Exactas y Naturales UBA Ciudad Universitaria Pab. I, (1428) Buenos Aires (Argentina)

2012-09-15

Langmuir probe measurements in an atmospheric pressure direct current (dc) plasma jet are reported. Sweeping probes were used. The experiment was carried out using a dc non-transferred arc torch with a rod-type cathode and an anode of 5 mm diameter. The torch was operated at a nominal power level of 15 kW with a nitrogen flow rate of 25 Nl min{sup -1}. A flat ion saturation region was found in the current-voltage curve of the probe. The ion saturation current to a cylindrical probe in a high-pressure non local thermal equilibrium (LTE) plasma was modeled. Thermal effects and ionization/recombination processes inside the probe perturbed region were taken into account. Averaged radial profiles of the electron and heavy particle temperatures as well as the electron density were obtained. An electron temperature around 11 000 K, a heavy particle temperature around 9500 K and an electron density of about 4 Multiplication-Sign 10{sup 22} m{sup -3}, were found at the jet centre at 3.5 mm downstream from the torch exit. Large deviations from kinetic equilibrium were found throughout the plasma jet. The electron and heavy particle temperature profiles showed good agreement with those reported in the literature by using spectroscopic techniques. It was also found that the temperature radial profile based on LTE was very close to that of the electrons. The calculations have shown that this method is particularly useful for studying spraying-type plasma jets characterized by electron temperatures in the range 9000-14 000 K.

Comparative Analysis of Carbon Plasma in Arc and RF Reactors

International Nuclear Information System (INIS)

Todorovic-Markovic, B.; Markovic, Z.; Mohai, I.; Szepvolgyi, J.

2004-01-01

Results on studies of molecular spectra emitted in the initial stages of fullerene formation during the processing of graphite powder in induction RF reactor and evaporation of graphite electrodes in arc reactor are presented in this paper. It was found that C2 radicals were dominant molecular species in both plasmas. C2 radicals have an important role in the process of fullerene synthesis. The rotational-vibrational temperatures of C2 and CN species were calculated by fitting the experimental spectra to the simulated ones. The results of optical emission study of C2 radicals generated in carbon arc plasma have shown that rotational temperature of C2 species depends on carbon concentration and current intensity significantly. The optical emission study of induction RF plasma and SEM analysis of graphite powder before and after plasma treatment have shown that evaporation of the processed graphite powder depends on feed rate and composition of gas phase significantly. Based on the obtained results, it was concluded that in the plasma region CN radicals could be formed by the reaction of C2 species with atomic nitrogen at smaller loads. At larger feed rate of graphite powder, CN species were produced by surface reaction of the hot carbon particles with nitrogen atoms. The presence of nitrogen in induction RF plasma reduces the fullerene yield significantly. The fullerene yield obtained in two different reactors was: 13% in arc reactor and 4.1% in induction RF reactor. However, the fullerene production rate was higher in induction RF reactor-6.4 g/h versus 1.7 g/h in arc reactor

Technical note: Nitrogen isotopic fractionation can be used to predict nitrogen-use efficiency in dairy cows fed temperate pasture.

Science.gov (United States)

Cheng, L; Sheahan, A J; Gibbs, S J; Rius, A G; Kay, J K; Meier, S; Edwards, G R; Dewhurst, R J; Roche, J R

2013-12-01

The objective of this study was to investigate the relationship between nitrogen isotopic fractionation (δ(15)N) and nitrogen-use efficiency (milk nitrogen/nitrogen intake; NUE) in pasture-fed dairy cows supplemented with increasing levels of urea to mimic high rumen degradable protein pastures in spring. Fifteen cows were randomly assigned to freshly cut pasture and either supplemented with 0, 250, or 336 g urea/d. Feed, milk, and plasma were analyzed for δ(15)N, milk and plasma for urea nitrogen concentration, and plasma for ammonia concentration. Treatment effects were tested using ANOVA and relationships between variables were established by linear regression. Lower dry matter intake (P = 0.002) and milk yield (P = 0.002) occurred with the highest urea supplementation (336 g urea/d) compared with the other two treatments. There was a strong linear relationship between milk δ(15)N - feed δ(15)N and NUE: [NUE (%) = 58.9 - 10.17 × milk δ(15)N - feed δ(15)N (‰) (r(2) = 0.83, P < 0.001, SE = 1.67)] and between plasma δ(15)N - feed δ(15)N and NUE: [NUE (%) = 52.4 - 8.61 × plasma δ(15)N - feed δ(15)N (‰) (r(2) = 0.85, P < 0.001, SE = 1.56)] . This study confirmed the potential use of δ(15)N to predict NUE in cows consuming different levels of rumen degradable protein.

Nitrogen gas plasma treatment of bacterial spores induces oxidative stress that damages the genomic DNA.

Science.gov (United States)

Sakudo, Akikazu; Toyokawa, Yoichi; Nakamura, Tetsuji; Yagyu, Yoshihito; Imanishi, Yuichiro

2017-01-01

Gas plasma, produced by a short high‑voltage pulse generated from a static induction thyristor power supply [1.5 kilo pulse/sec (kpps)], was demonstrated to inactivate Geobacillus stearothermophilus spores (decimal reduction time at 15 min, 2.48 min). Quantitative polymerase chain reaction and enzyme‑linked immunosorbent assays further indicated that nitrogen gas plasma treatment for 15 min decreased the level of intact genomic DNA and increased the level of 8-hydroxy-2'-deoxyguanosine, a major product of DNA oxidation. Three potential inactivation factors were generated during operation of the gas plasma instrument: Heat, longwave ultraviolet-A and oxidative stress (production of hydrogen peroxide, nitrite and nitrate). Treatment of the spores with hydrogen peroxide (3x2‑4%) effectively inactivated the bacteria, whereas heat treatment (100˚C), exposure to UV-A (75‑142 mJ/cm2) and 4.92 mM peroxynitrite (•ONOO‑), which is decomposed into nitrite and nitrate, did not. The results of the present study suggest the gas plasma treatment inactivates bacterial spores primarily by generating hydrogen peroxide, which contributes to the oxidation of the host genomic DNA.

Effect of radiation damping on the interaction of ultra-intense laser pulses with an overdense plasma

International Nuclear Information System (INIS)

Zhidkov, Alexei; Koga, James; Sasaki, Akira; Ueshima, Yutaka

2001-01-01

The effect of radiation damping on the interaction of an ultra-intense laser pulse with an overdense plasma is studied via relativistic particle-in-cell simulation. The calculation is performed for a Cu solid slab including ionization. We find a strong effect from radiation damping on the electron energy cut-off at about 150 MeV and on the absorption of a laser pulse with an intensity I=5x10 22 W/cm 2 and duration of 20 fs. Hot electrons reradiate more then 10% of the laser energy during the laser pulse. With the laser intensity, the energy loss due to the radiation damping increases as I 3 . In addition, we observe that the laser pulse may not propagate in the plasma even if ω pl 2 /ω 2 γ<1. The increase of skin depth with the laser intensity due to relativistic effects gives rise to the absorption efficiency. (author)

Particle-in-cell modeling of laser Thomson scattering in low-density plasmas at elevated laser intensities

Science.gov (United States)

Powis, Andrew T.; Shneider, Mikhail N.

2018-05-01

Incoherent Thomson scattering is a non-intrusive technique commonly used for measuring local plasma density. Within low-density, low-temperature plasmas and for sufficient laser intensity, the laser may perturb the local electron density via the ponderomotive force, causing the diagnostic to become intrusive and leading to erroneous results. A theoretical model for this effect is validated numerically via kinetic simulations of a quasi-neutral plasma using the particle-in-cell technique.

Relativistic effects in ultra-high-intensity laser-plasma interaction: electron parametric instabilities and ponderomotive force

International Nuclear Information System (INIS)

Quesnel, Brice

1998-01-01

This research thesis reports a theoretical and numeric study of the behaviour of two non linear phenomena of the laser-plasma interaction physics in a relativistic regime: the electronic parametric instabilities, and the ponderomotive force. In a first part, the author establishes the three-dimensional scattering relationship of electron parametric instabilities for a circularly polarised wave propagating in a homogeneous and cold plasma, without limitations of wave intensity, nor of plasma density. Results are verified by comparison with those of two-dimensional numerical simulations. The Weibel instability is also briefly studied in relativistic regime. In the second part, the author establishes an expression of the ponderomotive force exerted by an ultra-intense laser pulse in the vacuum about the focus point. A numerical code of integration of equations of motion of an electron in the laser field is used for the different expressions corresponding different approximation degrees. Results are used to interpret a recent experiment, and to critic other theoretical works [fr

21 CFR 862.1770 - Urea nitrogen test system.

Science.gov (United States)

2010-04-01

... 21 Food and Drugs 8 2010-04-01 2010-04-01 false Urea nitrogen test system. 862.1770 Section 862....1770 Urea nitrogen test system. (a) Identification. A urea nitrogen test system is a device intended to measure urea nitrogen (an end-product of nitrogen metabolism) in whole blood, serum, plasma, and urine...

[Measurement of plasma parameters in slot microplasma by optical emission spectrum].

Science.gov (United States)

Dong, Li-Fang; Lü, Ying-Hui; Liu, Wei-Yuan; Yue, Han; Lu, Ning; Li, Xin-Chun

2010-12-01

Slot microplasma was generated in argon and air mixture by using dielectric barrier discharge device with two parallel water electrodes. The molecular vibrational temperature, molecular rotational temperature and average electron energy of the slot plasma were studied by optical emission spectrum. The molecular vibrational temperature was calculated using the second positive system of nitrogen molecules ( C3 pi(u) --> B3 pi(g)). The molecular rotational temperature was calculated using the first negative system of nitrogen molecular ions ( B 2sigma(u)+ --> X sigma(g)+). The relative intensities of the first negative system of nitrogen molecular ions (391.4 nm) and nitrogen molecules in the excitation level (337.1 nm) emission spectrum line were measured for studying the variations of electron energy. It was found that the molecular vibrational temperature, molecular rotational temperature and average electron energy decrease with gas pressure increasing.

Bright ultrashort x-rays from intense subpicosecond laser-plasma interactions

International Nuclear Information System (INIS)

Umstadter, D.

1995-01-01

Short-pulse, high-intensity lasers interacting with solid targets make possible the study of a new class of laser-plasma interactions. They are unique because during the ultrashort laser pulse relatively little expansion occurs, and the density scale length remains much less than the laser wavelength. This makes possible the direct deposition of a significant amount of the laser energy at close to solid density. Steep plasma temperature and density gradients subsequently cause rapid cooling, resulting in highly non-equilibrium conditions and the concurrent emission of extremely bright ultrashort x-ray pulses. In this study, the latter are investigated experimentally with temporally and spectrally resolved soft x-ray diagnostics. The emitted x-ray spectra from solid targets with various atomic numbers are characterized for a laser pulse width τ l ∼ 400 fs. These ultrashort x rays may be used as (1) a diagnostic of solid-density plasma conditions, (2) a tool for the study of radiation hydrodynamics in a parameter regime that is otherwise inaccessible, and (3) a source for time-resolved diffraction, spectroscopy, or microscopy studies of transient chemical, biological or physical phenomena

Experimental investigation of the interaction of an intense laser beam with a long and hot plasma in the context of shock ignition

International Nuclear Information System (INIS)

Goyon, Clement

2014-01-01

Shock ignition is an alternative direct-drive scheme for inertial fusion that consists in two steps. The first one is a several nanoseconds long compression with low intensity beams. The second one is a several hundred of picoseconds stage using high intensity beams to create a converging shock leading to ignition. During the second phase, the laser beam goes through a long and hot under-critical plasma. However, the coupling of this intense pulse with the coronal plasma has not been much studied experimentally or numerically. Then, the energy absorbed as well as the role of parametric instabilities regarding reflected or transmitted intensity cannot be predicted. In this PhD dissertation, we describe an experimental study of an intense laser pulse between 2.10 15 W/cm 2 and 2.10 16 W/cm 2 interacting with millimetric plasma heated close to one keV. We begin with a theoretical description of the interaction conditions in the coronal plasma. Brillouin scattering is in strongly coupled regime, Raman instability is kinetic regime and laser intensity is above ponderomotive filamentation threshold. We recreate these interaction conditions experimentally by means of pre-heated targets which are foams or thin plastic foils. Then, we present the first measurements of time resolved backscattered spectra from the smoothed picosecond beam as well as transmitted intensity distribution through the plasma. We find that Brillouin instability can be responsible for up to 60% reflectivity in plasmas with electronic density close to critical while Raman reflectivity stays at low levels. Transmitted intensity distribution is smoothed by the propagation and its diameter increases compared to the laser focal spot in vacuum. Finally, we discuss interaction measurements in nanosecond regime to highlight the fact that parametric instabilities reduction is essential for shock ignition to be a successful scheme. (author) [fr

Capacitively coupled radio-frequency discharges in nitrogen at low pressures

KAUST Repository

Alves, Luís Lemos

2012-07-06

This paper uses experiments and modelling to study capacitively coupled radio-frequency (rf) discharges in pure nitrogen, at 13.56MHz frequency, 0.11 mbar pressures and 230W coupled powers. Experiments performed on two similar (not twin) setups, existing in the LATMOS and the GREMI laboratories, include electrical and optical emission spectroscopy (OES) measurements. Electrical measurements give the rf-applied and the direct-current-self-bias voltages, the effective power coupled to the plasma and the average electron density. OES diagnostics measure the intensities of radiative transitions with the nitrogen second-positive and first-negative systems, and with the 811.5 nm atomic line of argon (present as an actinometer). Simulations use a hybrid code that couples a two-dimensional time-dependent fluid module, describing the dynamics of the charged particles (electrons and positive ions N 2 + and N 4 + ), and a zero-dimensional kinetic module, describing the production and destruction of nitrogen (atomic and molecular) neutral species. The coupling between these modules adopts the local mean energy approximation to define spacetime-dependent electron parameters for the fluid module and to work out spacetime-averaged rates for the kinetic module. The model gives general good predictions for the self-bias voltage and for the intensities of radiative transitions (both average and spatially resolved), underestimating the electron density by a factor of 34. © 2012 IOP Publishing Ltd.

Effect of nitrogen-starvation, light intensity and iron on triacylglyceride/carbohydrate production and fatty acid profile of Neochloris oleoabundans HK-129 by a two-stage process.

Science.gov (United States)

Sun, Xian; Cao, Yu; Xu, Hui; Liu, Yan; Sun, Jianrui; Qiao, Dairong; Cao, Yi

2014-03-01

Triacylglyceride (TAG) and carbohydrate are potential feedstock for biofuels production. In this study, a two-stage process was applied for enhancing TAG/carbohydrate production in the selected microalgae - Neochloris oleoabundans HK-129. In stage I, effects of nitrogen, light intensity and iron on cell growth were investigated, and the highest biomass productivity of 292.83±5.83mg/L/d was achieved. In stage II, different nitrogen-starvation periods, light intensities and iron concentrations were employed to trigger accumulation of TAG and carbohydrate. The culture under 2-day N-starvation, 200μmol/m(2)/s light intensity and 0.037mM Fe(3+) concentration produced the maximum TAG and carbohydrate productivity of 51.58mg/L/d and 90.70mg/L/d, respectively. Nitrogen starvation period and light intensity had marked effects on TAG/carbohydrate accumulation and fatty acids profile, compared to iron concentration. The microalgal lipid was mainly composed of C16/C18 fatty acids (90.02%), saturated fatty acids (29.82%), and monounsaturated fatty acids (32.67%), which is suitable for biodiesel synthesis. Copyright © 2014 Elsevier Ltd. All rights reserved.

PLASMA PROTEIN AND HEMOGLOBIN PRODUCTION : DELETION OF INDIVIDUAL AMINO ACIDS FROM GROWTH MIXTURE OF TEN ESSENTIAL AMINO ACIDS. SIGNIFICANT CHANGES IN URINARY NITROGEN.

Science.gov (United States)

Robscheit-Robbins, F S; Miller, L L; Whipple, G H

1947-02-28

Given healthy dogs fed abundant iron and protein-free or low protein diets with sustained anemia and hypoproteinemia, we can study the capacity of these animals to produce simultaneously new hemoglobin and plasma protein. Reserve stores of blood protein-building materials are measurably depleted and levels of 6 to 8 gm. per cent for hemoglobin and 4 to 5 gm. per cent for plasma protein can be maintained for weeks or months depending upon the intake of food proteins or amino acid mixtures. These dogs are very susceptible to infection and various poisons. Dogs tire of these diets and loss of appetite terminates many experiments. Under these conditions (double depletion) standard growth mixtures of essential amino acids are tested to show the response in blood protein output and urinary nitrogen balance. As a part of each tabulated experiment one of the essential amino acids is deleted from the complete growth mixture to compare such response with that of the whole mixture. Methionine, threonine, phenylalanine, and tryptophane when singly eliminated from the complete amino acid mixture do effect a sharp rise in urinary nitrogen. This loss of urinary nitrogen is corrected when the individual amino acid is replaced in the mixture. Histidine, lysine, and valine have a moderate influence upon urinary nitrogen balance toward nitrogen conservation. Leucine, isoleucine, and arginine have minimal or no effect upon urinary nitrogen balance when these individual amino acids are deleted from the complete growth mixture of amino acids during 3 to 4 week periods. Tryptophane and to a less extent phenylalanine and threonine when returned to the amino acid mixture are associated with a conspicuous preponderance of plasma protein output over the hemoglobin output (Table 4). Arginine, lysine, and histidine when returned to the amino acid mixture are associated with a large preponderance of hemoglobin output. Various amino acid mixtures under these conditions may give a positive

Non-platinum nanocatalyst on porous nitrogen-doped carbon fabricated by cathodic vacuum arc plasma technique

Energy Technology Data Exchange (ETDEWEB)

Sirirak, Reungruthai [Material Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Department of Chemistry and Center of Excellence for Innovation in Chemistry (PERCH-CIC), Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Sarakonsri, Thapanee, E-mail: tsarakonsri@gmail.com [Material Science Research Center, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Department of Chemistry and Center of Excellence for Innovation in Chemistry (PERCH-CIC), Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand); Medhesuwakul, Min [Plasma & Beam Physics Research Facility, Department of Physics and Materials Science, Faculty of Science, Chiang Mai University, Chiang Mai 50200 (Thailand)

2015-11-30

Highlights: • High surface area porous coral-like nitrogen-doped carbon (NC) and non-platinum nanocatalysts were fabricated on proton exchange membrane using the cathodic vacuum arc plasma (CVAP) technique. • It is a one-step catalysts preparation directly on nafion proton exchange membrane. This CVAP technique is the first new method that was applied in a polymer electrolyte membrane fuel cells (PEMFCs) catalysts preparation. • Due to these excellent characteristics of nitrogen-doped carbon, it is expected to exhibit a good catalyst supporter for PEMFC. • In addition, the Fe–NC catalysts fabricated via this CVAP technique are sphere-like nanoparticle and well disperse on coral-like NC film, which particularity exhibits that these prepared catalysts ought to be a good oxygen reduction reaction (ORR) catalyst for PEMFC. • This approach can be extended to the synthesis of other non-platinum ORR catalyst for broad range applications in energy conversion. - Abstract: Polymer electrolyte membrane fuel cells (PEMFCs) convert chemical energy directly into electrical energy where catalysts composing of non-noble transition metals, nitrogen, and carbon compounds are the most promising materials to replace the expensive platinum catalysts for oxygen reduction reaction (ORR). In this research, cathodic vacuum arc plasma (CVAP) technique was used to fabricate porous nitrogen doped carbon (NC) and non-platinum catalyst on porous NC (Fe–NC) directly on ion exchange membrane for being used as an ORR catalyst at the cathode. The porous NC layer was fabricated on silicon wafer at 0.05 mTorr, 0.1 mTorr, 0.5 mTorr, 1 mTorr, and 5 mTorr of nitrogen gas inlet. The AFM, and SEM images are observed to be regularly big with quite high hillocks and thin NC layers; these results indicate that the optimum process pressure of nitrogen gas inlet is 5 mTorr for porous NC fabrication. The SEM–EDS detects Fe, N, and C elements in the prepared catalysts, and the XRD pattern reviews

Non-platinum nanocatalyst on porous nitrogen-doped carbon fabricated by cathodic vacuum arc plasma technique

International Nuclear Information System (INIS)

Sirirak, Reungruthai; Sarakonsri, Thapanee; Medhesuwakul, Min

2015-01-01

Highlights: • High surface area porous coral-like nitrogen-doped carbon (NC) and non-platinum nanocatalysts were fabricated on proton exchange membrane using the cathodic vacuum arc plasma (CVAP) technique. • It is a one-step catalysts preparation directly on nafion proton exchange membrane. This CVAP technique is the first new method that was applied in a polymer electrolyte membrane fuel cells (PEMFCs) catalysts preparation. • Due to these excellent characteristics of nitrogen-doped carbon, it is expected to exhibit a good catalyst supporter for PEMFC. • In addition, the Fe–NC catalysts fabricated via this CVAP technique are sphere-like nanoparticle and well disperse on coral-like NC film, which particularity exhibits that these prepared catalysts ought to be a good oxygen reduction reaction (ORR) catalyst for PEMFC. • This approach can be extended to the synthesis of other non-platinum ORR catalyst for broad range applications in energy conversion. - Abstract: Polymer electrolyte membrane fuel cells (PEMFCs) convert chemical energy directly into electrical energy where catalysts composing of non-noble transition metals, nitrogen, and carbon compounds are the most promising materials to replace the expensive platinum catalysts for oxygen reduction reaction (ORR). In this research, cathodic vacuum arc plasma (CVAP) technique was used to fabricate porous nitrogen doped carbon (NC) and non-platinum catalyst on porous NC (Fe–NC) directly on ion exchange membrane for being used as an ORR catalyst at the cathode. The porous NC layer was fabricated on silicon wafer at 0.05 mTorr, 0.1 mTorr, 0.5 mTorr, 1 mTorr, and 5 mTorr of nitrogen gas inlet. The AFM, and SEM images are observed to be regularly big with quite high hillocks and thin NC layers; these results indicate that the optimum process pressure of nitrogen gas inlet is 5 mTorr for porous NC fabrication. The SEM–EDS detects Fe, N, and C elements in the prepared catalysts, and the XRD pattern reviews

Designing plasmas for chronic wound disinfection

International Nuclear Information System (INIS)

Nosenko, T; Shimizu, T; Morfill, G E

2009-01-01

Irradiation with low-temperature atmospheric-pressure plasma provides a promising method for chronic wound disinfection. To be efficient for this purpose, plasma should meet the following criteria: it should significantly reduce bacterial density in the wounded area, cause a long-term post-irradiation inhibition of bacterial growth, yet without causing any negative effect on human cells. In order to design plasmas that would satisfy these requirements, we assessed the relative contribution of different components with respect to bactericidal properties due to irradiation with argon plasma. We demonstrate that plasma-generated UV radiation is the main short-term sterilizing factor of argon plasma. On the other hand, plasma-generated reactive nitrogen species (RNS) and reactive oxygen species (ROS) cause a long-term 'after-irradiation' inhibition of bacterial growth and, therefore, are important for preventing wound recolonization with bacteria between two treatments. We also demonstrate that at certain concentrations plasma-generated RNS and ROS cause significant reduction of bacterial density, but have no adverse effect on human skin cells. Possible mechanisms of the different effects of plasma-generated reactive species on bacteria and human cells are discussed. The results of this study suggest that argon plasma for therapeutic purposes should be optimized in the direction of reducing the intensity of plasma-generated UV radiation and increasing the density of non-UV plasma products.

Designing plasmas for chronic wound disinfection

Energy Technology Data Exchange (ETDEWEB)

Nosenko, T; Shimizu, T; Morfill, G E [Max-Planck Institute for Extraterrestrial Physics, Garching (Germany)], E-mail: tnosenko@mpe.mpg.de

2009-11-15

Irradiation with low-temperature atmospheric-pressure plasma provides a promising method for chronic wound disinfection. To be efficient for this purpose, plasma should meet the following criteria: it should significantly reduce bacterial density in the wounded area, cause a long-term post-irradiation inhibition of bacterial growth, yet without causing any negative effect on human cells. In order to design plasmas that would satisfy these requirements, we assessed the relative contribution of different components with respect to bactericidal properties due to irradiation with argon plasma. We demonstrate that plasma-generated UV radiation is the main short-term sterilizing factor of argon plasma. On the other hand, plasma-generated reactive nitrogen species (RNS) and reactive oxygen species (ROS) cause a long-term 'after-irradiation' inhibition of bacterial growth and, therefore, are important for preventing wound recolonization with bacteria between two treatments. We also demonstrate that at certain concentrations plasma-generated RNS and ROS cause significant reduction of bacterial density, but have no adverse effect on human skin cells. Possible mechanisms of the different effects of plasma-generated reactive species on bacteria and human cells are discussed. The results of this study suggest that argon plasma for therapeutic purposes should be optimized in the direction of reducing the intensity of plasma-generated UV radiation and increasing the density of non-UV plasma products.

Effect of near atmospheric pressure nitrogen plasma treatment on Pt/ZnO interface

International Nuclear Information System (INIS)

Nagata, Takahiro; Haemori, Masamitsu; Chikyow, Toyohiro; Yamashita, Yoshiyuki; Yoshikawa, Hideki; Kobayashi, Keisuke; Uehara, Tsuyoshi

2012-01-01

The effect of near atmospheric pressure nitrogen plasma (NAP) treatment of platinum (Pt)/zinc oxide (ZnO) interface was investigated. NAP can nitride the ZnO surface at even room temperature. Hard x-ray photoelectron spectroscopy revealed that NAP treatment reduced the surface electron accumulation at the ZnO surface and inhibited the Zn diffusion into the Pt electrode, which are critical issues affecting the Schottky barrier height and the ideality factor of the Pt/ZnO structure. After NAP treatment, the Pt Schottky contact indicated an improvement of electrical properties. NAP treatment is effective for the surface passivation and the Schottky contact formation of ZnO.

Control of proton beam divergence in intense-laser foil-plasma interaction

International Nuclear Information System (INIS)

Kawata, S.; Sonobe, R.; Miyazaki, S.; Sakai, K.; Kikuchi, T.

2006-01-01

Quality of an ion beam is one of the critical factors in intense-laser ion beam generation. A purpose of this study is the suppression of transverse proton divergence by a controlled electron cloud in laser-foil interactions. In this study, the foil target has a hole at the opposite side of the laser illumination. The electrons accelerated by an intense laser are limited in transverse by a neutral plasma at a protuberant part. Therefore the protons are accelerated and also controlled transversely by the electron cloud structure. In our 2.5-dimensional Particle-in-Cell simulations we demonstrate that the transverse shape of the electron cloud is well controlled and the collimated proton beam is generated successfully in the target with the hole. (authors)

Line intensity ratios of helium atom in an ionizing plasma

International Nuclear Information System (INIS)

Sasaki, Satoshi; Goto, Motoshi; Kato, Takako; Takamura, Shuichi

1998-10-01

Effective emission rate coefficients C em eff (λ), line intensity ratios, C em eff (λ 1 )/C em eff (λ 2 ), and S eff /C em eff (λ), with S eff the ionization rate coefficient, are obtained by the collisional radiative model for an ionizing plasma using new excitation and ionization rate coefficients. In the plasma with electron density n e > 10 4 cm -3 , C em eff (λ) for various lines are enlarged, since the normalized population densities for the metastable states, n(2 1,3 S)/n He , becomes large, and the excitation rate coefficients from 2 1,3 S, C 21,3S→i , are large compared to that from the ground state C 11S→i . In high n e plasma (n e > 10 12 cm -3 ), with frequent electron impacts on the excited heliums, n(i)/n He become constant to n e , which results in the decrease of C em eff (λ). Hot electrons and resonance scattering, which are often important for the experimental applications, are included in this model. A small amount of hot electrons (several percents) can enhance the line emission and ionization rates for low electron temperature plasma with T e (T e 1 S - n 1 P) and enlarges n 1 P and 2 1 S populations when the column density of helium gas n He x L exceeds 2x10 13 [cm -2 ]. (author)

Development of bipolar-pulse accelerator for intense pulsed ion beam acceleration

Energy Technology Data Exchange (ETDEWEB)

Masugata, Katsumi [Department of Electrical and Electronic System Engineering, Toyama University, 3190 Gofuku, Toyama 930-8555 (Japan)]. E-mail: masugata@eng.toyama-u.ac.jp; Shimizu, Yuichro [Department of Electrical and Electronic System Engineering, Toyama University, 3190 Gofuku, Toyama 930-8555 (Japan); Fujioka, Yuhki [Department of Electrical and Electronic System Engineering, Toyama University, 3190 Gofuku, Toyama 930-8555 (Japan); Kitamura, Iwao [Department of Electrical and Electronic System Engineering, Toyama University, 3190 Gofuku, Toyama 930-8555 (Japan); Tanoue, Hisao [National Institute of Advanced Industry Science and Technology, 1-1-1, Umezono, Tsukuba-shi, Ibaraki 305-8568 (Japan); Arai, Kazuo [National Institute of Advanced Industry Science and Technology, 1-1-1, Umezono, Tsukuba-shi, Ibaraki 305-8568 (Japan)

2004-12-21

To improve the purity of intense pulsed ion beams, a new type of pulsed ion beam accelerator named 'bipolar pulse accelerator' was proposed. To confirm the principle of the accelerator a prototype of the experimental system was developed. The system utilizes By type magnetically insulated acceleration gap and operated with single polar negative pulse. A coaxial gas puff plasma gun was used as an ion source, which was placed inside the grounded anode. Source plasma (nitrogen) of current density {approx}25A/cm2, duration {approx}1.5{mu}s was injected into the acceleration gap by the plasma gun. The ions were successfully accelerated from the grounded anode to the drift tube by applying negative pulse of voltage 240kV, duration 100ns to the drift tube. Pulsed ion beam of current density {approx}40A/cm2, duration {approx}50ns was obtained at 41mm downstream from the anode surface. To evaluate the irradiation effect of the ion beam to solid material, an amorphous silicon thin film of thickness {approx}500nm was used as the target, which was deposited on the glass substrate. The film was found to be poly-crystallized after 4-shots of the pulsed nitrogen ion beam irradiation.

Suppression of carbon desorption from 4H-SiC by irradiating a remote nitrogen plasma at a low temperature

Science.gov (United States)

Shimabayashi, Masaharu; Kurihara, Kazuaki; Sasaki, Koichi

2018-05-01

We remotely irradiated a nitrogen plasma onto the carbon-side surface of 4H-SiC at a low temperature, and examined the effect of sample cooling on the characteristics of the nitride layer. An improved nitride layer, which had higher concentrations of carbon and silicon and a lower concentration of oxygen, was formed in the region at depths of more than 0.6–0.9 nm from the top surface. The depth of the fragile nitride layer in the top region, where no improved characteristics of the nitride layer were observed, became smaller with sample cooling. In addition, on the basis of the experimental results, we discussed the difference in the activation energy of the nitriding reaction of 4H-SiC supported by atomic nitrogen and molecular nitrogen in the metastable \\text{A}3Σ \\text{u} + state.

Nitrogen plasma immersion ion implantation for surface treatment and wear protection of austenitic stainless steel X6CrNiTi1810

International Nuclear Information System (INIS)

Blawert, C.; Mordike, B.L.

1999-01-01

Plasma immersion ion implantation is an effective surface treatment for stainless steels. The influence of treatment parameters (temperature, plasma density and pressure) on the sliding wear resistance are studied here. At moderate temperatures, nitrogen remains in solid solution without forming nitrides. This increases the surface hardness and the wear resistance without affecting the passivation of the steel. This may allow the use of such steels in applications where their poor wear resistance would normally prohibit their use. (orig.)

On the inversion problem of the plasma line intensity measurements in terms of photoelectron fluxes

International Nuclear Information System (INIS)

Lejeune, G.

1979-01-01

Assuming that the unidimensional distribution function of the photoelectron flux can be determined from plasma line intensity measurement, it is shown that the photoelectron flux distribution is not uniquely determined if additional hypotheses are not made. The limitations of the inversion procedure are shown: in particular, plasma line measurements cannot allow the determination of more than the first two Legendre components of the photoelectron flux. Experimental procedures for this determination are finally reviewed. (author)

Plasma exchange in the intensive care unit: Technical aspects and complications.

Science.gov (United States)

Lemaire, Aurélie; Parquet, Nathalie; Galicier, Lionel; Boutboul, David; Bertinchamp, Rémi; Malphettes, Marion; Dumas, Guillaume; Mariotte, Eric; Peraldi, Marie-Noëlle; Souppart, Virginie; Schlemmer, Benoit; Azoulay, Elie; Canet, Emmanuel

2017-12-01

Data on plasma exchange therapy in the intensive care unit (ICU) setting are scarce. We aimed to describe the technical aspects and the adverse events associated with the procedure in critically ill patients. All adult patients treated by plasma exchange in the medical ICU of the Saint-Louis university hospital between January 1, 2013 and March 31, 2015 were prospectively included. We report on 260 plasma exchange procedures performed in 50 patients. The centrifugation technique was used for 159 (61%) procedures and the filtration technique for the other 101 (39%) procedures. Both techniques had similar efficacy to treat hyperviscosity syndrome (n = 18). Seventy (26.9%) of the 260 plasma exchange procedures were reported with at least one adverse reaction. Centrifugation and filtration techniques had similar rates of adverse reactions (23.9 vs. 31.7%, P = .19). Hypotension was the most reported (n = 21, 8%) and correlates with a low hematocrit before therapy. Most complications were related to allergic reactions to the replacement fluids. Coagulation disorders depended on the type of replacement fluid. The post-exchange fibrinogen level was decreased by 54% [48;66] with albumin 5%, and 4% [-5;17] with plasma frozen within 24 h. Twenty-three (22.8%) of the 101 filtration procedures experienced filter clotting. Filter clotting was associated with a higher volume exchange prescribed when compared to procedures without filter clotting (4600 [4000;5000] ml vs. 3900 [3600;4800] ml, P < .01). Plasma exchange is a relatively safe and generally well-tolerated procedure in the ICU setting. Most adverse events are unpredictable and related to minor allergic reactions. © 2017 Wiley Periodicals, Inc.

High-intensity interval training lowers blood pressure and improves apelin and NOx plasma levels in older treated hypertensive individuals.

Science.gov (United States)

Izadi, Mohammad Reza; Ghardashi Afousi, Alireza; Asvadi Fard, Maryam; Babaee Bigi, Mohammad Ali

2018-02-01

Hypertension is the major risk factor for cardiovascular diseases and is one of the primary causes of morbidity and mortality worldwide. Apelin levels and NO bioavailability are impaired in older hypertensive patients. Exercise is an effective intervention for treating hypertension. Our purpose was to evaluate the effect of high-intensity interval training on blood pressure, apelin, and NOx plasma levels in older treated hypertensive individuals. Thirty treated hypertensive subjects (61.70 ± 5.78 years, 17 males, 13 females) were randomly divided into 6 weeks of high-intensity interval training (n = 15) and control (n = 15). The exercise training was conducted for three 35-min sessions a week (1.5-min interval at 85-90% of heart rate reserve [HRR] and 2 min active phase at 50-55% of HRR). Assessment of plasma apelin, nitrite/nitrate (NOx), and endothelin-1 (ET-1) was performed before and after the intervention. At the end of the study, apelin, and NOx plasma levels increased significantly in the high-intensity interval training (HIIT) group (P = 0.021, P = 0.003, respectively). Conversely, ET-1 plasma levels significantly decreased in the training group after the intervention (P = 0.015). Moreover, there was a positive correlation between the change of plasma apelin and change of plasma NOx (r = 0. 771, P = 0.0008). In addition, there was a negative correlation between the change of plasma ET-1, change of plasma apelin (r = - 0.595, P = 0.019), and variation of NOx (r = - 0.572, P = 0.025). This study indicates that, by increasing of apelin and NOx plasma levels, HIIT may be effective in reducing blood pressure.

Laser plasma as a source of intense attosecond pulses via high-order harmonic generation

International Nuclear Information System (INIS)

Ozaki, T.

2013-01-01

The incredible progress in ultrafast laser technology and Ti:sapphire lasers have lead to many important applications, one of them being high-order harmonic generation (HHG). HHG is a source of coherent extreme ultraviolet (XUV) radiation, which has opened new frontiers in science by extending nonlinear optics and time-resolved spectroscopy to the XUV region, and pushing ultrafast science to the attosecond domain. Progress in attosecond science has revealed many new phenomena that have not been seen with femtosecond pulses. Clearly, the next frontier is to study nonlinear effects at the attosecond timescale and in the XUV. However, a problem with present-day attosecond pulses is that they are just too weak to induce measurable nonlinearities, which severely limits the application of this source. While HHG from solid targets has shown promise for higher conversion efficiency, there is no experiment so far that demonstrates isolated attosecond pulse generation. The generation of isolated, several 100-as pulses with few-µJ energy will enable us to enter a completely new phase in attoscience. In past works, we have demonstrated that high-order harmonics from lowly ionized plasma is a highly efficient method to generate coherent XUV pulses. For example, indium plasma has been shown to generate intense 13th harmonic of the Ti:sapphire laser, with conversion efficiency of 10-4. However, the quasi-monochromatic nature of indium harmonics would make it difficult to generate attosecond pulses. We have also demonstrated that one could increase the harmonic yield by using nanoparticle targets. Specifically, we showed that by using indium oxide nanoparticles or C60 film, we could obtain intense harmonics between wavelengths of 50 to 90 nm. The energy in each of these harmonic orders was measured to be a few µJ, which is sufficient for many applications. However, the problem of using nanoparticle or film targets is the rapid decrease in the harmonic intensity, due to the rapid

Tribological properties of nitrogen-containing amorphous carbon film produced by dc plasma chemical vapor deposition

International Nuclear Information System (INIS)

Zhang Wei; Wazumi, Koichiro; Tanaka, Akihiro; Koga, Yoshinori

2003-01-01

The nitrogen-contained amorphous carbon (a-C:N) films were deposited in a dc plasma chemical vapor deposition system with different substrate bias voltages. The structural, mechanical, and tribological properties of the a-C:N films were investigated. The influence of the bias voltage on the tribological behaviors of the a-C:N films was evaluated under various environments (dry air, O 2 , N 2 , and vacuum) using a ball-on-disk friction tester. It showed that the sp 3 C and hydrogen concentration of the a-C:N films decreases with increasing the bias voltage. However, the nitrogen concentration increases with increasing the bias voltage. As a result, the hardness and internal stress decrease and the critical load for fracturing increases as the substrate bias increases. For the tribological properties of the a-C:N films, the friction coefficient of the films slightly decreases in the environments of N 2 , O 2 , or dry air, but increases slightly in the vacuum environment by increasing the bias voltage. It indicates that the incorporated nitrogen in the a-C:N films would decrease the friction coefficient of the films in N 2 or O 2 environments, but slightly increases the friction coefficient of the films in a vacuum. The excellent wear resistance of the a-C:N films, in the level of 10 -9 -10 -8 mm 3 /Nm, can be observed in N 2 , vacuum, and dry air environments. In addition, the effect of the bias voltage on the wear rate of the a-C:N films becomes less obvious by nitrogen incorporation. So, we suggest the incorporated nitrogen, which bonded to carbon and restrained the increase of the fraction of sp 2 C-C, would restrain the wear of the a-C:N films in different environments, especially in dry air

Exercise-intensity dependent alterations in plasma redox status do not reflect skeletal muscle redox-sensitive protein signaling.

Science.gov (United States)

Parker, Lewan; Trewin, Adam; Levinger, Itamar; Shaw, Christopher S; Stepto, Nigel K

2018-04-01

Redox homeostasis and redox-sensitive protein signaling play a role in exercise-induced adaptation. The effects of sprint-interval exercise (SIE), high-intensity interval exercise (HIIE) and continuous moderate-intensity exercise (CMIE), on post-exercise plasma redox status are unclear. Furthermore, whether post-exercise plasma redox status reflects skeletal muscle redox-sensitive protein signaling is unknown. In a randomized crossover design, eight healthy adults performed a cycling session of HIIE (5×4min at 75% W max ), SIE (4×30s Wingate's), and CMIE work-matched to HIIE (30min at 50% of W max ). Plasma hydrogen peroxide (H 2 O 2 ), thiobarbituric acid reactive substances (TBARS), superoxide dismutase (SOD) activity, and catalase activity were measured immediately post, 1h, 2h and 3h post-exercise. Plasma redox status biomarkers were correlated with phosphorylation of skeletal muscle p38-MAPK, JNK, NF-κB, and IκBα protein content immediately and 3h post-exercise. Plasma catalase activity was greater with SIE (56.6±3.8Uml -1 ) compared to CMIE (42.7±3.2, pexercise plasma TBARS and SOD activity significantly (pexercise protocol. A significant positive correlation was detected between plasma catalase activity and skeletal muscle p38-MAPK phosphorylation 3h post-exercise (r=0.40, p=0.04). No other correlations were detected (all p>0.05). Low-volume SIE elicited greater post-exercise plasma catalase activity compared to HIIE and CMIE, and greater H 2 O 2 compared to CMIE. Plasma redox status did not, however, adequately reflect skeletal muscle redox-sensitive protein signaling. Copyright © 2017 Sports Medicine Australia. Published by Elsevier Ltd. All rights reserved.

Heating of a dense plasma with an intense relativistic electron beam: initial observations

International Nuclear Information System (INIS)

Montgomery, M.D.; Parker, J.V.; Riepe, K.B.; Sheffield, R.L.

1981-01-01

A dense (approx. 10 17 cm -3 ) plasma has been heated via the relativistic two-stream instability using a 3 MeV, intense (5 x 10 5 A/cm 2 ) electron beam. Evidence for heating has been obtained with diamagnetic loops, thin-foil witness plates, and a 2-channel, broad-band soft x-ray detector. Measurements of energy loss from the beam using calorimetry techniques have been attempted. The measured strong dependence of heating on beam transverse temperature and the very short interaction length ( 100 ns after the beam pulse are consistent with a plasma temperature <150 eV and line emission near 80 to 90 eV

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.

Probing ultrafast dynamics of solid-density plasma generated by high-contrast intense laser pulses

Science.gov (United States)

Jana, Kamalesh; Blackman, David R.; Shaikh, Moniruzzaman; Lad, Amit D.; Sarkar, Deep; Dey, Indranuj; Robinson, Alex P. L.; Pasley, John; Ravindra Kumar, G.

2018-01-01

We present ultrafast dynamics of solid-density plasma created by high-contrast (picosecond contrast ˜10-9), high-intensity (˜4 × 1018 W/cm2) laser pulses using time-resolved pump-probe Doppler spectrometry. Experiments show a rapid rise in blue-shift at early time delay (2-4.3 ps) followed by a rapid fall (4.3-8.3 ps) and then a slow rise in blue-shift at later time delays (>8.3 ps). Simulations show that the early-time observations, specifically the absence of any red-shifting of the reflected probe, can only be reproduced if the front surface is unperturbed by the laser pre-pulse at the moment that the high intensity pulse arrives. A flexible diagnostic which is capable of diagnosing the presence of low-levels of pre-plasma formation would be useful for potential applications in laser-produced proton and ion production, such as cancer therapy and security imaging.

The Modeling of Nitrogen Mass Transport in CoCr Alloys

Directory of Open Access Journals (Sweden)

Petraitienė Akvilė

2016-12-01

Full Text Available The kinetics of plasma nitriding of CoCr alloy below temperatures of nitrides formation and mechanisms of nitrogen penetration are analyzed by proposed kinetic modeling in this article. Proposed nitrogen diffusion model is based on the trapping – detrapping (TD model and developed taking into account the effect of the concentration dependent diffusivity of nitrogen, nitrogen adsorption on the surface of alloy and surface swelling process. The model indicates the influence of chromium atoms to nitrogen atoms diffusivity. The model consists of time and depth dependent diffusion, which is described by a partial differential equation, and it is solved by using Crank – Nicolson finite difference method. By fitting of experimental nitrogen depth profiles, it is shown that nitrogen diffusion coefficient varies with nitrogen concentration according to Einstein-Smoluchowski relation. Nitrogen depth profiles in plasma nitrided medical grade CoCr alloy (ISO 5831 – 12 at T = 400 °C for 1, 4 and 20 hours calculated on the basis of this model are in good agreement with experimental nitrogen profiles. Furthermore, the swelling process is showed and analyzed, derived the dependency of swelling rate on nitriding duration – the swelling rate is inversely proportional to the square root of nitriding duration. The obtained diffusion coefficient value and the swelling process rates satisfy the experimental data form Ref. The derived model explains physical processes during plasma nitriding and allows obtaining nitrogen depth profiles for any requisite nitriding duration.

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

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

Time-dependent simulation of plasma and electrodes in high-intensity discharge lamps with different electrode shapes

CERN Document Server

Flesch, P

2003-01-01

The subject of this paper is the modelling of d.c. and a.c. high-intensity Hg-discharge lamps with differently shaped electrodes. Different arc attachments on the electrodes are studied and insight for the development of new electrodes is gained. The model includes the entire discharge plasma (plasma column, hot plasma spots in front of electrodes, near-electrode non-LTE-plasma) as well as anode and cathode. No subdivision of the discharge space into different regions is necessary (like space charge layer, ionization zone, plasma column). This is achieved by using a differential equation for a non-LTE electrical conductivity which is applicable for local thermal equilibrium (LTE-)regions as well as for non-LTE plasma regions close to the electrodes in a high pressure plasma. Modelling results for a 0.6 MPa mercury discharge considering six different electrode shapes (anode and cathode) are presented and compared with experimental results. The electrodes have different diameters and different electrode tips, s...

Diagnostics of N2 Ar plasma mixture excited in a 13.56 MHz hollow cathode discharge system: application to remote plasma treatment of polyamide surface

Science.gov (United States)

Saloum, S.; Naddaf, M.; Alkhaled, B.

2008-02-01

N2-x% Ar plasma gas mixture, generated in a hollow cathode RF discharge system, has been characterized by both optical emission spectroscopy (OES) and double Langmuir probe, as a function of experimental parameters: total pressure (5-33 Pa), and different fractions of argon (7 <= x <= 80), at a constant applied RF power of 300 W. N2 dissociation degree has been investigated qualitatively by both the actinometry method and the ratio I_N/I_{N_2} of the atomic nitrogen line emission intensity at 672.3 nm to the vibrational band (0-0) of the N2 second positive system at 337.1 nm. Both methods showed that the increase in argon fraction enhances the dissociation of N2, with a maximum at x = 50 for the pressure of 5 Pa, although the two methods give two opposite trends as a function of total pressure. Spectroscopic measurements showed that the vibrational temperature of the N2 second positive system increases with both argon fraction and total pressure increase, it lies between 4900 and 12 300 K. Langmuir probe measurements showed that, in the remote zone, the electron temperature falls in the range 1.57-1.75 eV, the N_{2}^{+} density varies between 5 × 109 and 1.4 × 1010 cm-3 and that both the plasma ionization degree and electron temperature increase towards the source. In addition, the process of plasma-polyamide (PA) surface interaction, in the remote plasma zone, has been studied through OES analysis during plasma treatment of PA to monitor the possible emissions due to the polymer etching. An increase in atomic nitrogen line (672.3 nm) intensity is obtained, atomic carbon line (833.52 nm) and the band emission (0-0) from the CN (B 2Σ+-X 2Σ+) violet system were observed. The PA surface modification has been confirmed through the improvement of its hydrophilic character as the water contact angle measured after the plasma treatment significantly decreased.

Diagnostics of N2-Ar plasma mixture excited in A 13.56 MHz hollow cathode discharge system: Application to remote plasma treatment of polyamide surface

International Nuclear Information System (INIS)

Saloum, S.; Naddaf, M.; Al-khaled, B.

2009-01-01

N 2 -x % Ar plasma gas mixture, generated in a hollow cathode RF discharge system, has been characterized by both optical emission spectroscopy (OES) and double langmuir probe, as a function of experimental parameters: Total pressure (5-33 Pa), and different fractions of argon (7≤ x ≤ 80), at a constant applied RF power of 300 W. N 2 dissociation degree has been investigated qualitatively by both actinometry method and the ratio of the atomic nitrogen line emission intensity at 672.3 nm to the vibrational band (0-0) of the N 2 second positive system at 337.1 nm. Both methods showed that the increase of argon fraction enhances the dissociation of N 2 , with a maximum at x=50 for the pressure of 5 Pa, although the two methods give two opposite trends as a function of total pressure. Spectroscopic measurements showed that the vibrational temperature of N 2 second positive system increases with both argon fraction and total pressure increase, it lies between 4900 K and 12300 K. Langmuir probe measurements showed that, in the remote zone, the electron temperature falls in the range 1.57-1.75 eV, the N 2 + density varies between 5.10 9 cm-3 and 1.4 10 10 cm -3 , and that both the plasma ionization degree and electron temperature increase towards the source. In addition, the process of plasma-polyamide surface interaction, in the remote plasma zone, has been studied through optical emission spectroscopy analysis during plasma treatment of polyamide to monitor the possible emissions due to the polymer etching. An increase of atomic nitrogen line (672.3 nm) intensity is obtained, atomic carbon line (833.52 nm) and the band emission (0-0) from CN (B 2 Σ + -X 2 Σ + ) violet system were observed. The polyamide surface modification has been confirmed through the improvement of its hydrophilic character as the water contact angle measured after the plasma treatment significantly decreased. (author)

Diagnostics of N2-Ar plasma mixture excited in a 13.56 MHz hollow cathode discharge system: application to remote plasma treatment of polyamide surface

International Nuclear Information System (INIS)

Saloum, S; Naddaf, M; Alkhaled, B

2008-01-01

N 2 -x% Ar plasma gas mixture, generated in a hollow cathode RF discharge system, has been characterized by both optical emission spectroscopy (OES) and double Langmuir probe, as a function of experimental parameters: total pressure (5-33 Pa), and different fractions of argon (7 ≤ x ≤ 80), at a constant applied RF power of 300 W. N 2 dissociation degree has been investigated qualitatively by both the actinometry method and the ratio I N /I N 2 of the atomic nitrogen line emission intensity at 672.3 nm to the vibrational band (0-0) of the N 2 second positive system at 337.1 nm. Both methods showed that the increase in argon fraction enhances the dissociation of N 2 , with a maximum at x = 50 for the pressure of 5 Pa, although the two methods give two opposite trends as a function of total pressure. Spectroscopic measurements showed that the vibrational temperature of the N 2 second positive system increases with both argon fraction and total pressure increase, it lies between 4900 and 12 300 K. Langmuir probe measurements showed that, in the remote zone, the electron temperature falls in the range 1.57-1.75 eV, the N 2 + density varies between 5 x 10 9 and 1.4 x 10 10 cm -3 and that both the plasma ionization degree and electron temperature increase towards the source. In addition, the process of plasma-polyamide (PA) surface interaction, in the remote plasma zone, has been studied through OES analysis during plasma treatment of PA to monitor the possible emissions due to the polymer etching. An increase in atomic nitrogen line (672.3 nm) intensity is obtained, atomic carbon line (833.52 nm) and the band emission (0-0) from the CN (B 2 Σ + -X 2 Σ + ) violet system were observed. The PA surface modification has been confirmed through the improvement of its hydrophilic character as the water contact angle measured after the plasma treatment significantly decreased

Pulsed, atmospheric pressure plasma source for emission spectrometry

Science.gov (United States)

Duan, Yixiang; Jin, Zhe; Su, Yongxuan

2004-05-11

A low-power, plasma source-based, portable molecular light emission generator/detector employing an atmospheric pressure pulsed-plasma for molecular fragmentation and excitation is described. The average power required for the operation of the plasma is between 0.02 W and 5 W. The features of the optical emission spectra obtained with the pulsed plasma source are significantly different from those obtained with direct current (dc) discharge higher power; for example, strong CH emission at 431.2 nm which is only weakly observed with dc plasma sources was observed, and the intense CN emission observed at 383-388 nm using dc plasma sources was weak in most cases. Strong CN emission was only observed using the present apparatus when compounds containing nitrogen, such as aniline were employed as samples. The present apparatus detects dimethylsulfoxide at 200 ppb using helium as the plasma gas by observing the emission band of the CH radical. When coupled with a gas chromatograph for separating components present in a sample to be analyzed, the present invention provides an apparatus for detecting the arrival of a particular component in the sample at the end of the chromatographic column and the identity thereof.

Anomalous intensities of Ne-like ion resonance line in plasma produced by picosecond laser pulse

International Nuclear Information System (INIS)

Bryunetkin, B.A.; Skobelev, I.Yu.; Faenov, A.Ya.; Kalashnikov, M.P.; Nikles, P.; Shnyupep, M.

1995-01-01

An anomalous structure of intensities of spectral lines of CuXX and GeXXX Ne-like ions emitted by plasma produced by laser pulses of picosecond duration and up to 2x10 18 W/cm 2 flux density is recorded for the first time. It is shown that spectrum maximum of these ions is emitted from a plasma region whose density is significantly above the critical value of the length of heating laser radiation wave. 9 refs.; 3 figs

A novel femtosecond-gated, high-resolution, frequency-shifted shearing interferometry technique for probing pre-plasma expansion in ultra-intense laser experiments

Energy Technology Data Exchange (ETDEWEB)

Feister, S., E-mail: feister.7@osu.edu; Orban, C. [Department of Physics, The Ohio State University, Columbus, Ohio 43210 (United States); Innovative Scientific Solutions, Inc., Dayton, Ohio 45459 (United States); Nees, J. A. [Innovative Scientific Solutions, Inc., Dayton, Ohio 45459 (United States); Center for Ultra-Fast Optical Science, University of Michigan, Ann Arbor, Michigan 48109 (United States); Morrison, J. T. [Fellow, National Research Council, Washington, D.C. 20001 (United States); Frische, K. D. [Innovative Scientific Solutions, Inc., Dayton, Ohio 45459 (United States); Chowdhury, E. A. [Department of Physics, The Ohio State University, Columbus, Ohio 43210 (United States); Intense Energy Solutions, LLC., Plain City, Ohio 43064 (United States); Roquemore, W. M. [Air Force Research Laboratory, Dayton, Ohio 45433 (United States)

2014-11-15

Ultra-intense laser-matter interaction experiments (>10{sup 18} W/cm{sup 2}) with dense targets are highly sensitive to the effect of laser “noise” (in the form of pre-pulses) preceding the main ultra-intense pulse. These system-dependent pre-pulses in the nanosecond and/or picosecond regimes are often intense enough to modify the target significantly by ionizing and forming a plasma layer in front of the target before the arrival of the main pulse. Time resolved interferometry offers a robust way to characterize the expanding plasma during this period. We have developed a novel pump-probe interferometry system for an ultra-intense laser experiment that uses two short-pulse amplifiers synchronized by one ultra-fast seed oscillator to achieve 40-fs time resolution over hundreds of nanoseconds, using a variable delay line and other techniques. The first of these amplifiers acts as the pump and delivers maximal energy to the interaction region. The second amplifier is frequency shifted and then frequency doubled to generate the femtosecond probe pulse. After passing through the laser-target interaction region, the probe pulse is split and recombined in a laterally sheared Michelson interferometer. Importantly, the frequency shift in the probe allows strong plasma self-emission at the second harmonic of the pump to be filtered out, allowing plasma expansion near the critical surface and elsewhere to be clearly visible in the interferograms. To aid in the reconstruction of phase dependent imagery from fringe shifts, three separate 120° phase-shifted (temporally sheared) interferograms are acquired for each probe delay. Three-phase reconstructions of the electron densities are then inferred by Abel inversion. This interferometric system delivers precise measurements of pre-plasma expansion that can identify the condition of the target at the moment that the ultra-intense pulse arrives. Such measurements are indispensable for correlating laser pre-pulse measurements

Emission spectra from super-critical rippled plasma density profiles illuminated by intense laser pulses

International Nuclear Information System (INIS)

Ondarza R, R.; Boyd, T.J.M.

2000-01-01

High-order harmonic emission from the interaction of intense femtosecond laser pulses with super-critical plasmas characterized by a rippled density profile at the vacuum-plasma interface has been observed from particle-in-cell (PIC) simulations. A plasma simulation box several laser wavelengths in extent was prepared with a rippled density of a fraction of a laser wavelength. Emission spectra at the very initial stage of the interaction were recorded with spectral characteristics dissimilar to those previously reported in the literature. The reflected light spectra were characterized by a strong emission at the plasma line and by a series of harmonics at multiples of the ripple frequency. Harmonic spectra were obtained for different values of the plasma ripple frequency. In all cases the harmonics were emitted at the precise multiple harmonic number of the ripple frequency. Another important feature apparent from the simulations was that the emission peaks appeared to havea complex structure as compared with those for unrippled plasmas. For the cases when the plasma was rippled the peaks that corresponded to the multiples of the rippled density typically showed a double peak for the first few harmonics. The reflected emission plots for the main laser pulse showed strong emission at the plasma frequency and at multiples of that frequency as reported by the authors in the literature. (Author)

The effect of high intensity laser propagation instabilities on channel formation in underdense plasmas

International Nuclear Information System (INIS)

Najmudin, Z.; Krushelnick, K.; Tatarakis, M.; Clark, E.L.; Danson, C.N.; Malka, V.; Neely, D.; Santala, M.I.K.; Dangor, A.E.

2003-01-01

Experiments have been performed using high power laser pulses (up to 50 TW) focused into underdense helium plasmas (n e ≤5x10 19 cm -3 ). Using shadowgraphy, it is observed that the laser pulse can produce irregular density channels, which exhibit features such as long wavelength hosing and 'sausage-like' self-focusing instabilities. This phenomenon is a high intensity effect and the characteristic period of oscillation of these instabilities is typically found to correspond to the time required for ions to move radially out of the region of highest intensity

Hydrophobic recovery of repeatedly plasma-treated silicone rubber .2. A comparison of the hydrophobic recovery in air, water, or liquid nitrogen

NARCIS (Netherlands)

Everaert, EP; VanderMei, HC; Busscher, HJ

1996-01-01

Surfaces of medical grade silicone rubber (Q7-4750, Dow Coming) were modified by repeated (six times) RF plasma treatments using various discharge gases: oxygen, argon, carbon dioxide, and ammonia. The treated samples were stored for a period of 3 months in ambient air, water, or liquid nitrogen.

Measurements of magnetic fields generated in underdense plasmas by intense lasers

International Nuclear Information System (INIS)

Najmudin, Z.; Walton, B. R.; Mangles, S. P. D.; Dangor, A. E.; Krushelnick, K.; Fritzler, S.; Malka, V.; Faure, J.; Tatarakis, M.

2006-01-01

Measurements have been made of the magnetic field generated by the passage of high intensity short laser pulses through underdense plasmas. For a 30 fs, 1 J, 800 nm linearly-polarised laser pulse, an azimuthal magnetic field is observed at a radial extent of approximately 200 μm. The field is found to exceed 2.8 MG. For a 1 ps, 40 J, 1054 nm circularly-polarised laser pulse, a solenoidal field is observed that can exceed 7 MG. This solenoidal field is absent with linear polarised light, and hence can be considered as an Inverse Faraday effect. Both types of field are found to decay on the picosecond timescale. For both the azimuthal and solenoidal fields produced by such intense lasers, the production of energetic electrons by the interaction is thought to be vital for magnetic field generation

Instabilities in superconductors and in intense laser produced plasma's

International Nuclear Information System (INIS)

Banerjee, Satyajit S.; Mohan, Shyam; Sinha, Jaivardhan; Kahaly, Subendhu; Ravindra Kumar, G.

2007-01-01

In this talk I will attempt to discuss phenomena's in two areas of physics which appear quite divorced from each other, viz., superconductivity and plasma's. The first portion of the talk will describe the behavior of a collection of vortices in superconductors in a random pinning environment. Vortices manifest themselves in a variety of systems, like in fluids and in type II superconductors. A collection of vortices inside superconductors behaves like an elastic media. Investigating this elastic medium of the vortex state is a convenient prototype for investigating similar physics in a wide variety of systems, viz., charge density waves, Wigner crystals, magnetic domains, etc. The behavior of all these systems can be generalized under, nature of elastic media in the presence of a random pinning environment and thermal fluctuations. Based on the idea that softer matter is easy to pin we have attempted to investigate how the vortex lattice disorders as its gets softer. Surprisingly we find evidence to two distinct types of instabilities in the vortex lattice instead of one. These two instabilities produce vastly different effects on certain quantities associated with the extent of disorder in the superconductor. It appears that prior to softening of the vortex state, a heterogeneously pinned state of the vortex matter appears, perhaps through a KT like transition. In the second part of the talk, I will attempt to describe some of our recent results pertaining to instabilities and the appearance of giant magnetic fields in plasma's. These results have been obtained with a high sensitivity magneto-optical imaging setup we have developed at IIT Kanpur. Using the setup, we investigate distribution of magnetic fields around dense solid plasmas generated by intense p-polarized laser (∼10 16 Wcm -2 , 100 fs) irradiation of magnetic tapes, using high sensitivity magneto optical imaging technique. We demonstrate giant axial magnetic fields and map out for the first time

Treatment of methyl orange by nitrogen non-thermal plasma in a corona reactor: The role of reactive nitrogen species

Energy Technology Data Exchange (ETDEWEB)

Cadorin, Bruno Mena, E-mail: brunomenacadorin@gmail.com [Department of Chemistry, Universidade Federal de Santa Catarina (Brazil); Tralli, Vitor Douglas [Department of Chemistry, Universidade Federal de Santa Catarina (Brazil); Ceriani, Elisa [Department of Chemical Sciences, Università di Padova (Italy); Benetoli, Luís Otávio de Brito [Department of Chemistry, Universidade Federal de Santa Catarina (Brazil); Marotta, Ester, E-mail: ester.marotta@unipd.it [Department of Chemical Sciences, Università di Padova (Italy); Ceretta, Claudio [Department of Industrial Engineering, Università di Padova (Italy); Debacher, Nito Angelo [Department of Chemistry, Universidade Federal de Santa Catarina (Brazil); Paradisi, Cristina [Department of Chemical Sciences, Università di Padova (Italy)

2015-12-30

Highlights: • Nitration of methyl orange is one of the main processes in treatment with N{sub 2}-plasma. • MS/MS analysis shows preferred nitration of methyl orange in ortho position. • N{sub 2} plasma, N{sub 2}-PAW, reaction with NO{sub 2}{sup −} or NO{sub 2}{sup −}/H{sub 2}O{sub 2} at pH 2 give the same products. - Abstract: Methyl orange (MO) azo dye served as model organic pollutant to investigate the role of reactive nitrogen species (RNS) in non-thermal plasma (NTP) induced water treatments. The results of experiments in which MO aqueous solutions were directly exposed to N{sub 2}-NTP are compared with those of control experiments in which MO was allowed to react with nitrite, nitrate and hydrogen peroxide, which are species formed in water exposed to N{sub 2}-NTP. Treatment of MO was also performed in PAW, Plasma Activated Water, that is water previously exposed to N{sub 2}-NTP. Both direct N{sub 2}-NTP and N{sub 2}-PAW treatments induced the rapid decay of MO. No appreciable reaction was instead observed when MO was treated with NO{sub 3}{sup −} and H{sub 2}O{sub 2} either under acidic or neutral pH. In contrast, in acidic solutions MO decayed rapidly when treated with NO{sub 2}{sup −} and with a combination of NO{sub 2}{sup −} and H{sub 2}O{sub 2}. Thorough product analysis was carried out by HPLC coupled with UV–vis and ESI–MS/MS detectors. In all experiments in which MO reaction was observed, the major primary product was a derivative nitro-substituted at the ortho position with respect to the N,N-dimethylamino group of MO. The reactions of RNS are discussed and a mechanism for the observed nitration products is proposed.

Effects of endurance training on reduction of plasma glucose during high intensity constant and incremental speed tests in Wistar rats

Directory of Open Access Journals (Sweden)

P. Abreu

Full Text Available The aim of this research was to investigate the effects of endurance training on reduction of plasma glucose during high intensity constant and incremental speed tests in Wistar rats. We hypothesized that plasma glucose might be decreased in the exercised group during heavy (more intense exercise. Twenty-four 10-week-old male Wistar rats were randomly assigned to sedentary and exercised groups. The prescription of endurance exercise training intensity was determined as 60% of the maximum intensity reached at the incremental speed test. The animals were trained by running on a motorized treadmill, five days/week for a total period of 67 weeks. Plasma glucose during the constant speed test in the exercised group at 20 m/min was reduced at the 14th, 21st and 28th min compared to the sedentary group, as well at 25 m/min at the 21st and 28th min. Plasma glucose during the incremental speed test was decreased in the exercised group at the moment of exhaustion (48th min compared to the sedentary group (27th min. Endurance training positively modulates the mitochondrial activity and capacity of substrate oxidation in muscle and liver. Thus, in contrast to other studies on high load of exercise, the effects of endurance training on the decrease of plasma glucose during constant and incremental speed tests was significantly higher in exercised than in sedentary rats and associated with improved muscle and hepatic oxidative capacity, constituting an important non-pharmacological intervention tool for the prevention of insulin resistance, including type 2 diabetes mellitus.

Pulsed hollow cathode discharge: intense electron beam and filamentary plasma

International Nuclear Information System (INIS)

Modreanu, Gabriel

1998-01-01

This work deals with a transient hollow cathode discharge optimised by a preionization one and providing intense electron beams. It exists a preionization current value for which the pulsed discharge becomes a very straight and bright filament, well collimated on the discharge tube axis for some tenths of centimeters. A remarkable feature of this discharge is that, without internal metallic electrodes very pure plasma could be produced. Using self-biasing by the beam of a Faraday cup placed only few millimeters behind the anode, we deduced the beam electron's distribution function and its temporal behavior for two radial positions, on the axis and 1 millimeter off-axis, respectively. The real advantage of this measurement technique is the transient polarization character, which allows analysis very closely from the electron beam extraction hole. On the other side, using the emission spectroscopy, we have studied the plasma produced in electron beam - gas interaction and deduced the temporal evolution of the electron temperature. The temporal behavior of the filamentary plasma diameter shows a constriction at the last moments of the beam existence, followed by diffusion controlled expansion. The ambipolar diffusion coefficient corresponding to the estimated electron temperature describes quite well this expansion and allows a quantitative interpretation of the measured temperature diminution, with taking into account the preferential fast electrons escape. The analysis of both beam and post-beam plasma phases suggests potential applications of this robust, very reproducible and not expensive discharge also susceptible to be external monitored. The beam - target interaction could be used for PVD, elementary analysis and filamentary or point-like X-ray emission. (author) [fr

Temporal development of the plasma composition of Zr and Cr metal plasma streams in a N2 environment

International Nuclear Information System (INIS)

Rosen, Johanna; Anders, Andre; Hultman, Lars; Schneider, Jochen M.

2003-01-01

We describe the temporal development of the plasma composition in a pulsed plasma stream generated by cathodic arc. Cathodes of Zr and Cr were operated at various nitrogen pressures. The time resolved plasma composition for the cathode materials was analyzed with time-of-flight charge-to-mass spectrometry, and was found to be a strong function of the nitrogen pressure. Large plasma composition gradients were detected within the first 60 (micro)s of the pulse, the nitrogen ion concentration increasing with increasing pressure. The results are explained by the formation and erosion of a compound layer formed at the cathode surface in the presence of a reactive gas. The average charge state was also found to be affected by the reactive gas pressure as well as by the time after ignition. The charge states were highest in the beginning of the pulse at low nitrogen pressure, decreasing to a steady-state value at higher pressure. These results are of importance for reactive plasma processing and for controlling of the evolution of thin film composition and microstructure

Electron Acceleration and the Propagation of Ultrashort High-Intensity Laser Pulses in Plasmas

International Nuclear Information System (INIS)

Wang, Xiaofang; Krishnan, Mohan; Saleh, Ned; Wang, Haiwen; Umstadter, Donald

2000-01-01

Reported are interactions of high-intensity laser pulses (λ=810 nm and I≤3x10 18 W /cm 2 ) with plasmas in a new parameter regime, in which the pulse duration (τ=29 fs ) corresponds to 0.6-2.6 plasma periods. Relativistic filamentation is observed to cause laser-beam breakup and scattering of the beam out of the vacuum propagation angle. A beam of megaelectronvolt electrons with divergence angle as small as 1 degree sign is generated in the forward direction, which is correlated to the growth of the relativistic filamentation. Raman scattering, however, is found to be much less than previous long-pulse results. (c) 2000 The American Physical Society

Nitrogen implantation in tungsten and migration in the fusion experiment ASDEX upgrade

International Nuclear Information System (INIS)

Meisl, Gerd Korbinian

2015-01-01

The implantation of nitrogen ions into tungsten was studied in laboratory experiments to understand the interaction of nitrogen containing fusion plasmas with tungsten walls. The resulting model of W-N interaction was tested by experiments in the tokamak ASDEX Upgrade. Using the measurements from these experiments as boundary condition, nitrogen transport and re-distribution in the plasma were modeled by self-consistent WallDYN-DIVIMP simulations.

Characterization of a Low Intensity Plasma Jet

International Nuclear Information System (INIS)

Urruchi, W. I.; Maciel, H.S.; Petraconi, G.; Otani, C.

1999-01-01

A source of streaming plasma having charged particles energies in the range of tens of electron volts has been built and characterized. The source is based on a dc glow discharge in a cylindrical tube which is connected to a vacuum chamber through a small orifice. A streaming plasma of conical shape emerging from the orifice is formed when the discharge is run between the cathode located inside the tube and the anode located in the vacuum chamber. The strong constriction of the discharge leads to the formation of a plasma sac, in the orifice region, between the positive column and the plasma beam. Properties of these plasmas were investigated using a movable Langmuir probe and an electrostatic energy analyzer. A mechanism based on the formation of double-layers (DL) between the ''plasma sac'' and the adjacent plasmas is proposed to explain the acceleration of the plasma jet charged particles. (author)

Different Land Use Intensities in Grassland Ecosystems Drive Ecology of Microbial Communities Involved in Nitrogen Turnover in Soil

OpenAIRE

Meyer, Annabel; Focks, Andreas; Radl, Viviane; Keil, Daniel; Welzl, Gerhard; Sch?ning, Ingo; Boch, Steffen; Marhan, Sven; Kandeler, Ellen; Schloter, Michael

2013-01-01

Understanding factors driving the ecology of N cycling microbial communities is of central importance for sustainable land use. In this study we report changes of abundance of denitrifiers, nitrifiers and nitrogen-fixing microorganisms (based on qPCR data for selected functional genes) in response to different land use intensity levels and the consequences for potential turnover rates. We investigated selected grassland sites being comparable with respect to soil type and climatic conditions,...

Studies of intense-laser plasma instabilities

Czech Academy of Sciences Publication Activity Database

Láska, Leoš; Krása, Josef; Badziak, J.; Jungwirth, Karel; Krouský, Eduard; Margarone, Daniele; Parys, P.

2013-01-01

Roč. 272, May (2013), 94-98 ISSN 0169-4332 R&D Projects: GA MŠk(CZ) 7E09092; GA MŠk(CZ) LC528; GA AV ČR IAA100100715 Institutional research plan: CEZ:AV0Z10100523 Keywords : laser plasma instabilities * self-generated magnetic field * longitudinal structure of the expanding plasma Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 2.538, year: 2013

A comparative study of nitrogen plasma effect on field emission characteristics of single wall carbon nanotubes synthesized by plasma enhanced chemical vapor deposition

Energy Technology Data Exchange (ETDEWEB)

Kumar, Avshish; Parveen, Shama; Husain, Samina; Ali, Javid [Department of Physics, Jamia Millia Islamia (A Central University), New Delhi 110025 (India); Zulfequar, Mohammad [Department of Physics, Jamia Millia Islamia (A Central University), New Delhi 110025 (India); Centre for Nanoscience and Nanotechnology, Jamia Millia Islamia (A Central University), New Delhi 110025 (India); Harsh [Centre for Nanoscience and Nanotechnology, Jamia Millia Islamia (A Central University), New Delhi 110025 (India); Husain, Mushahid, E-mail: mush_reslab@rediffmail.com [Department of Physics, Jamia Millia Islamia (A Central University), New Delhi 110025 (India); Centre for Nanoscience and Nanotechnology, Jamia Millia Islamia (A Central University), New Delhi 110025 (India)

2014-12-15

Highlights: • Vertically aligned single wall carbon nanotubes (SWCNTs) have been successfully grown on nickel (Ni) deposited silicon substrate. • The diameter distribution of the grown (SWCNTs) is in the range 1–2 nm. • A current density of 25.0 mA/cm{sup 2} at 1.9 V/μm of the grown SWCNTs is observed with a high turn-on field (E{sub to}) of 1.3 V/μm. • After N{sub 2} nitrogen plasma treatment, huge current density of 81.5 mA/cm{sup 2} at 2.0 V/μm was recorded with low E{sub to} of 1.2 V/μm. • The comparison of these two typical results indicates a drastic enhancement in the field emission properties after plasma treatments. - Abstract: Vertically aligned single wall carbon nanotubes (SWCNTs) with large scale control of diameter, length and alignment have successfully been grown by plasma enhanced chemical vapor deposition (PECVD) system. The nickel (Ni) as catalyst deposited on silicon (Si) substrate was used to grow the SWCNTs. Field emission (FE) characteristics of the as grown SWCNTs were measured using indigenously designed setup in which a diode is configured in such a way that by applying negative voltage on the copper plate (cathode) with respect to stainless steel anode plate, current density can be recorded. To measure the FE characteristics, SWCNTs film pasted on the copper plate with silver epoxy was used as electron emitter source. The effective area of anode was ∼78.5 mm{sup 2} for field emission measurements. The emission measurements were carried out under high vacuum pressure of the order of 10{sup −6} Torr to minimize the electron scattering and degradation of the emitters. The distance between anode and cathode was kept 500 μm (constant) during entire field emission studies. The grown SWCNTs are excellent field emitters, having emission current density higher than 25 mA/cm{sup 2} at turn-on field 1.3 V/μm. In order to enhance the field emission characteristics, the as grown SWCNTs have been treated under nitrogen (N{sub 2

Performance of plasma facing materials under intense thermal loads in tokamaks and stellarators

Energy Technology Data Exchange (ETDEWEB)

Linke, J.; Hirai, T.; Roedig, M.; Singheiser, L. [Forschungszentrum Juelich GmbH, EURATOM Association, Juelich (Germany)

2003-07-01

Beside quasi-stationary plasma operation, short transient thermal pulses with deposited energy densities in the order of several ten MJm{sup -2} are a serious concern for next step devices, in particular for tokamak devices such as ITER. The most serious of these transient events are plasma disruptions. Here a considerable fraction of the plasma energy is deposited on a localized surface area in the divertor strike zone region; the time scale of these events is typically in the order of 1 ms. In spite of the fact that a dense cloud of ablation vapour will form above the strike zone, only partial shielding of the divertor armour from incident plasma particles will occur. As a consequence, thermal shock induced crack formation, vaporization, surface melting, melt layer ejection, and particle emission induced by brittle destruction processes will limit the lifetime of the components. In addition, dust particles (neutron activated metals or tritium enriched carbon) are a serious concern form a safety point of view. Other transient heat loads which occasionally occur in magnetic confinement experiments such as instabilities in the plasma positioning (vertical displacement events) also may cause irreversible damage to plasma facing components (PFC), particularly to metals such as beryllium and tungsten. Another serious damage to PFCs is due to intense fluxes of 14 MeV neutrons in D-T-burning plasma devices. Integrated neutron fluence of several ten dpa in future thermonuclear fusion reactors will degrade essential physical properties of the components (e.g. thermal conductivity); another serious concern is the embrittlement of the heat sink and the plasma facing materials (PFM). (orig.)

Ion energy distributions from laser-generated plasmas at two different intensities

Science.gov (United States)

Ceccio, Giovanni; Torrisi, Lorenzo; Okamura, Masahiro; Kanesue, Takeshi; Ikeda, Shunsuke

2018-01-01

Laser-generated non-equilibrium plasmas were analyzed at Brookhaven National Laboratory (NY, USA) and MIFT Messina University (Italy). Two laser intensities of 1012 W/cm2 and 109 W/cm2, have been employed to irradiate Al and Al with Au coating targets in high vacuum conditions. Ion energy distributions were obtained using electrostatic analyzers coupled with ion collectors. Time of flight measurements were performed by changing the laser irradiation conditions. The study was carried out to provide optimum keV ions injection into post acceleration systems. Possible applications will be presented.

Experimental Simulation of Beryllium Armour Damage Under ITER-like Intense Transient Plasma Loads

Energy Technology Data Exchange (ETDEWEB)

Kupriyanov, I.; Basaleev, E.; Nikolaev, G.; Kurbatova, L., E-mail: igkupr@gmail.com [A.A. Bochvar High Technology Research Institute of Inorganic Material, Moscow (Russian Federation); Podkovyrov, V.; Zhitlukhin, A. [SRC RF TRINITI, Troitsk (Russian Federation); Khimchenko, L. L. [Project Centre of ITER, Moscow (Russian Federation)

2012-09-15

Full text: Beryllium will be used as a plasma facing material in the next generation of tokamaks such as ITER. During plasma operation in ITER, the plasma facing materials and components will be suffered by different kinds of loading which may affect their surface or their joint to the heat sink. In addition to quasi-stationary loadings which are caused by the normal cycling operation, the plasma facing components and materials may also be exposed to the intense short transient loads like disruptions, ELMs. All these events may lead to beryllium surface melting, cracking, evaporation and erosion. It is expected that the erosion of beryllium under transient plasma loads such as ELMs and disruptions will mainly determine a lifetime of ITER first wall. To obtain the experimental data for the evaluation of the beryllium armor lifetime and dust production under ITER-relevant transient loads, the advanced plasma gun QSPA-Be facility has been constructed in Bochvar Institute. This paper presents recent results of the experiments with Russian beryllium of TGP-56FW ITER grade. The mock-ups of a special design armored with two beryllium targets (80 x 80 x 10 mm{sup 3}) were tested by hydrogen plasma streams (5 cm in diameter) with pulse duration of 0.5 ms and heat load of 0.5 and 1.0 MJ/m{sup 2}. Experiments were performed at RT temperature. The evolution of surface microstructure and profile, cracks morphology and mass loss/gain under erosion process on the beryllium surface exposed to up to 250 shots will be presented and discussed. (author)

Trends in nitrogen concentrations and load in 48 minor streams draining intensively farmed Danish catchments, 1990-2014. How can the observed trend be explained?

Science.gov (United States)

Windolf, Jørgen; Børgesen, Christen; Blicher-Mathiesen, Gitte; Kronvang, Brian; Larsen, Søren E.; Tornbjerg, Henrik

2016-04-01

The total land-based nitrogen load to Danish coastal waters has decreased by 50% since 1990 through a reduction of the outlet of nitrogen from sewage point sources and diffuse sources. On a national scale nitrogen load from diffuse sources, has been reduced by 43% , mainly due to limitation of the amount of N input to different crops, rules for timing and application of manure, mandatory demands for catch crops and restoration of wetlands. The latter increasing the nitrogen retention capacity in surface waters. However, on a local scale huge variations exist in the reduction of the diffuse nitrogen load. Since 1990, an important part of the Danish national monitoring program on the aquatic environment (NOVANA) has been directed at quantifying the nitrogen concentrations and load in 48 minor streams draining small intensively farmed catchments. The 48 catchments have a mean size of 18 km2, farmed area constitutes more than 60% of the catchment area and the catchments have no significant outlets of sewage to the streams. The statistical trend results (based on a seasonal Mann-Kendall) from these 48 streams show a 9-65% reduction in the diffuse nitrogen load (mean: 48%). The large differences in trends in the diffuse N load are related to differences in catchment-specific variables such as nitrogen surpluses, nitrogen leaching from the root zone, hydrogeology and nitrogen retention in ground and surface waters.

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

Study in the plasma with non-equilibrium ionization state by relative intensities in K-spectra of multicharged ions

International Nuclear Information System (INIS)

Bojko, V.A.; Skobelev, I.Yu.; Faenov, A.Ya.

1984-01-01

The pressure of the K-spectra formation of multicharge h-, He-, Li-like ions in a plasma with an arbitrary ionization state are considered. It is shown that comparison of experimental and theoretical data on the intensities of f a number of spectral lines belonging to such ions allows one to determine both the plasma electron temperature and ion distribution versus the ionization degre ees. The proposed method of plasma diagnostics is used for measuring parameters of the expanding laser-produced magnesium plasme

High-intensity laser physics

International Nuclear Information System (INIS)

Mohideen, U.

1993-01-01

This thesis is a study of the effect of high intensity lasers on atoms, free electrons and the generation of X-rays from solid density plasmas. The laser produced 50 milli Joule 180 femto sec pulses at 5 Hz. This translates to a maximum intensity of 5 x 10 18 W/cm 2 . At such high fields the AC stark shifts of atoms placed at the focus is much greater than the ionization energy. The characteristics of multiphoton ionization of atoms in intense laser fields was studied by angle resolved photoelectron spectroscopy. Free electrons placed in high intensity laser fields lead to harmonic generation. This phenomenon of Nonlinear Compton Scattering was theoretically investigated. Also, when these high intensity pulses are focused on solids a hot plasma is created. This plasma is a bright source of a short X-ray pulse. The pulse-width of X-rays from these solid density plasmas was measured by time-resolved X-ray spectroscopy

Study on the intense relativistic electron beam propagation in a collisionless plasma of small density

International Nuclear Information System (INIS)

Korenev, S.A.; Rubin, N.B.; Khodataev, K.V.

1982-01-01

The results of the experimental studies of the intense relativistic electron beam (IREB) propagation with ν/γ approximately 0.1, and γ approximately 1.6 (γ is an electron beam relativistic factor) in a collisionless plasma of small density over the 180 cm length are presented. Plasma is generated with the incomplete discharge over dielectric surface at the residual gas pressure of P approximately 10 -5 Torr. It is shown that the transportation efficiency may be essentially high, if the electron concentration in plasma satisfies the equilibrium conditions and if it is less or equal to the electron concentration in a beam. At concentration less than optimum one, the transportation efficiency decreases due to violations of equilibrium conditions. At high concentration the transportation efficiency also decreased due to the scattering and breaking on excited small-scale and plasma oscillations. The IREB propagation occurs without essential time delay under optimum conditions

Surfaces in the interaction of intense long wavelength laser light with plasmas

International Nuclear Information System (INIS)

Jones, R.D.

1985-01-01

The role of surface in the interaction of intense CO 2 laser light with plasmas is reviewed. The collisionless absorption of long wavelength light is discussed. Specific comments on the role of ponderomotive forces and profile steepening on resonant absorption are made. It is shown that at intensities above 10 15 W/cm 2 the absorption is determined by ion acoustic-like surface modes. It is demonstrated experimentally that harmonics up to the forty-sixth can be generated in steep density profiles. Computer simulations and theoretical mechanisms for this phenomena are presented. The self generation of magnetic fields on surfaces is discussed. The role these fields play in the lateral transport of energy, the insulation of the target from hot electrons, and the acceleration of fast ions is discussed

Tungsten oxide coatings deposited by plasma spray using powder and solution precursor for detection of nitrogen dioxide gas

Energy Technology Data Exchange (ETDEWEB)

Zhang, Chao, E-mail: zhangc@yzu.edu.cn [College of Mechanical Engineering, Yangzhou University, Yangzhou 225127 (China); Wang, Jie [College of Mechanical Engineering, Yangzhou University, Yangzhou 225127 (China); Geng, Xin [College of Mechanical Engineering, Yangzhou University, Yangzhou 225127 (China); College of Chemistry and Chemical Engineering, Yangzhou University, Yangzhou 225002 (China)

2016-05-25

Increasing attention has been paid on preparation methods for resistive-type gas sensors based on semiconductor metal oxides. In this work, tungsten oxide (WO{sub 3}) coatings were prepared on alumina substrates and used as gas sensitive layers. The coatings were deposited by atmospheric plasma spray using powder, solution precursor, or a combination of both. Tungsten oxide powder through a powder port and ammonium tungstate aqueous solution through a liquid port were injected into plasma stream respectively or together to deposit WO{sub 3} coatings. Phase structures in the coatings were characterized by X-ray diffraction analyzer. The field-emission scanning electron microscopy images confirmed that the coatings were in microstructure, nanostructure or micro-nanostructure. The sensing properties of the sensors based on the coatings exposed to 1 ppm nitrogen dioxide gas were characterized in a home-made instrument. Sensing properties of the coatings were compared and discussed. The influences of gas humidity and working temperature on the sensor responses were further studied. - Highlights: • Porous gas sensitive coatings were deposited by plasma spray using powder and solution precursor. • Crystallized WO{sub 3} were obtained through hybrid plasma spray plus a pre-conditioned step. • Plasma power had an important influence on coating microstructure. • The particle size of atmospheric plasma-sprayed microstructured coating was stable. • Solution precursor plasma-sprayed WO{sub 3} coatings had nanostructure and showed good responses to 1 ppm NO{sub 2}.

Plasma ion emission from high intensity picosecond laser pulse interactions with solid targets

International Nuclear Information System (INIS)

Fews, A.P.; Norreys, P.A.; Beg, F.N.; Bell, A.R.; Dangor, A.E.; Danson, C.N.; Lee, P.; Rose, S.J.

1994-01-01

The fast ion emission from high intensity, picosecond laser plasmas has been measured to give the characteristic ion energy and the amount of laser energy transferred to ions with energies ≥100 keV/nucleon as a function of incident intensity. The characteristic ion energy varies from 0.2 to 1.3 MeV over the range 2.0x10 17 --2.0x10 18 W cm -2 . Ten percent of the laser energy is transferred into MeV ions at 2.0x10 18 W cm -2 . Calculations of stopping power in high density materials are presented that show that fast ions cannot be ignored in modeling fast ignitor schemes

Magnetic properties of Co-N films deposited by ECR nitrogen/argon plasma with DC negative-biased Co target

Energy Technology Data Exchange (ETDEWEB)

Li, H.; Zhang, Y.C.; Yang, K.; Liu, H.X.; Zhu, X.D., E-mail: xdzhu@ustc.edu.cn; Zhou, H.Y.

2017-06-01

Highlights: • A new method of synthesizing Co-N films containing Co{sub 4}N phase. • Tunable magnetic properties achieved in ECR plasma CVD. • The change of magnetic properties is related to atoms mobility on substrate and the concentration of active species in plasma vapor. - Abstract: By introducing DC negative-biased Co target in the Electron Cyclotron Resonance (ECR) nitrogen/argon plasma, the Co-N films containing Co{sub 4}N phase were synthesized on Si(100) substrate. Effects of processing parameters on magnetic properties of the films are investigated. It is found that magnetic properties of Co-N films vary with N{sub 2}/Ar flow ratio, substrate temperature, and target biasing voltage. The saturation magnetization M{sub s} decreased by increasing the N{sub 2}/Ar gas flow ratio or decreasing target biasing voltage, while the coercive field H{sub c} increased, which is ascribed to the variation of relative concentration for N or Co active species in plasma vapor. The magnetic properties present complex dependency with growth temperature, which is related to the atom mobility on the substrate affected by the growth temperature. This study exhibits a potential of ECR plasma chemical vapor deposition to synthesize the interstitial compounds and tune magnetic properties of films.

Characteristics of an Electron Cyclotron Resonance Plasma Source for the Production of Active Nitrogen Species in III-V Nitride Epitaxy

Science.gov (United States)

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

1997-01-01

A simple analysis is provided to determine the characteristics of an electron cyclotron resonance (ECR) plasma source for the generation of active nitrogen species in the molecular beam epitaxy of III-V nitrides. The effects of reactor geometry, pressure, power, and flow rate on the dissociation efficiency and ion flux are presented. Pulsing the input power is proposed to reduce the ion flux.

Nitrogen balance and groundwater nitrate contamination: Comparison among three intensive cropping systems on the North China Plain

Energy Technology Data Exchange (ETDEWEB)

Ju, X.T. [Key Laboratory of Plant-Soil Interactions, Ministry of Education, College of Agricultural Resources and Environmental Sciences, China Agricultural University, Beijing 100094 (China); Kou, C.L. [Key Laboratory of Plant-Soil Interactions, Ministry of Education, College of Agricultural Resources and Environmental Sciences, China Agricultural University, Beijing 100094 (China); Institute of Soils and Fertilizers, Henan Academy of Agricultural Sciences, Zhengzhou 450002 (China); Zhang, F.S. [Key Laboratory of Plant-Soil Interactions, Ministry of Education, College of Agricultural Resources and Environmental Sciences, China Agricultural University, Beijing 100094 (China)]. E-mail: zfs@cau.edu.cn; Christie, P. [Key Laboratory of Plant-Soil Interactions, Ministry of Education, College of Agricultural Resources and Environmental Sciences, China Agricultural University, Beijing 100094 (China); Agricultural and Environmental Science Department, Queen' s University Belfast, Belfast BT9 5PX (United Kingdom)

2006-09-15

The annual nitrogen (N) budget and groundwater nitrate-N concentrations were studied in the field in three major intensive cropping systems in Shandong province, north China. In the greenhouse vegetable systems the annual N inputs from fertilizers, manures and irrigation water were 1358, 1881 and 402 kg N ha{sup -1} on average, representing 2.5, 37.5 and 83.8 times the corresponding values in wheat (Triticum aestivum L.)-maize (Zea mays L.) rotations and 2.1, 10.4 and 68.2 times the values in apple (Malus pumila Mill.) orchards. The N surplus values were 349, 3327 and 746 kg N ha{sup -1}, with residual soil nitrate-N after harvest amounting to 221-275, 1173 and 613 kg N ha{sup -1} in the top 90 cm of the soil profile and 213-242, 1032 and 976 kg N ha{sup -1} at 90-180 cm depth in wheat-maize, greenhouse vegetable and orchard systems, respectively. Nitrate leaching was evident in all three cropping systems and the groundwater in shallow wells (<15 m depth) was heavily contaminated in the greenhouse vegetable production area, where total N inputs were much higher than crop requirements and the excessive fertilizer N inputs were only about 40% of total N inputs. - Intensive greenhouse vegetable production systems may pose a greater nitrogen pollution threat than apple orchards or cereal rotations to soil and water quality in north China.

Nitrogen balance and groundwater nitrate contamination: Comparison among three intensive cropping systems on the North China Plain

International Nuclear Information System (INIS)

Ju, X.T.; Kou, C.L.; Zhang, F.S.; Christie, P.

2006-01-01

The annual nitrogen (N) budget and groundwater nitrate-N concentrations were studied in the field in three major intensive cropping systems in Shandong province, north China. In the greenhouse vegetable systems the annual N inputs from fertilizers, manures and irrigation water were 1358, 1881 and 402 kg N ha -1 on average, representing 2.5, 37.5 and 83.8 times the corresponding values in wheat (Triticum aestivum L.)-maize (Zea mays L.) rotations and 2.1, 10.4 and 68.2 times the values in apple (Malus pumila Mill.) orchards. The N surplus values were 349, 3327 and 746 kg N ha -1 , with residual soil nitrate-N after harvest amounting to 221-275, 1173 and 613 kg N ha -1 in the top 90 cm of the soil profile and 213-242, 1032 and 976 kg N ha -1 at 90-180 cm depth in wheat-maize, greenhouse vegetable and orchard systems, respectively. Nitrate leaching was evident in all three cropping systems and the groundwater in shallow wells (<15 m depth) was heavily contaminated in the greenhouse vegetable production area, where total N inputs were much higher than crop requirements and the excessive fertilizer N inputs were only about 40% of total N inputs. - Intensive greenhouse vegetable production systems may pose a greater nitrogen pollution threat than apple orchards or cereal rotations to soil and water quality in north China

Time-resolved plasma spectroscopy of thin foils heated by a relativistic-intensity short-pulse laser

International Nuclear Information System (INIS)

Audebert, P.; Gauthier, J.-C.; Shepherd, R.; Fournier, K.B.; Price, D.; Lee, R.W.; Springer, P.; Peyrusse, O.; Klein, L.

2002-01-01

Time-resolved K-shell x-ray spectra are recorded from sub-100 nm aluminum foils irradiated by 150-fs laser pulses at relativistic intensities of Iλ 2 =2x10 18 W μm 2 /cm 2 . The thermal penetration depth is greater than the foil thickness in these targets so that uniform heating takes place at constant density before hydrodynamic motion occurs. The high-contrast, high-intensity laser pulse, broad spectral band, and short time resolution utilized in this experiment permit a simplified interpretation of the dynamical evolution of the radiating matter. The observed spectrum displays two distinct phases. At early time, ≤500 fs after detecting target emission, a broad quasicontinuous spectral feature with strong satellite emission from multiply excited levels is seen. At a later time, the He-like resonance line emission is dominant. The time-integrated data is in accord with previous studies with time resolution greater than 1 ps. The early time satellite emission is shown to be a signature of an initial large area, high density, low-temperature plasma created in the foil by fast electrons accelerated by the intense radiation field in the laser spot. We conclude that, because of this early time phenomenon and contrary to previous predictions, a short, high-intensity laser pulse incident on a thin foil does not create a uniform hot and dense plasma. The heating mechanism has been studied as a function of foil thickness, laser pulse length, and intensity. In addition, the spectra are found to be in broad agreement with a hydrodynamic expansion code postprocessed by a collisional-radiative model based on superconfiguration average rates and on the unresolved transition array formalism

Intense Magnetized Plasma-Wall Interaction

Energy Technology Data Exchange (ETDEWEB)

Bauer, Bruno S. [UNR; Fuelling, Stephan [UNR

2013-11-30

This research project studied wall-plasma interactions relevant to fusion science. Such interactions are a critical aspect of Magneto-Inertial Fusion (MIF) because flux compression by a pusher material, in particular the metal for the liner approach to MIF, involves strong eddy current heating on the surface of the pusher, and probably interactions and mixing of the pusher with the interior fuel during the time when fusion fuel is being burned. When the pusher material is a metal liner, high-energy-density conditions result in fascinating behavior. For example, "warm dense matter" is produced, for which material properties such as resistivity and opacity are not well known. In this project, the transformation into plasma of metal walls subjected to pulsed megagauss magnetic fields was studied with an experiment driven by the UNR 1 MA Zebra generator. The experiment was numerically simulated with using the MHRDR code. This simple, fundamental high-energy-density physics experiment, in a regime appropriate to MIF, has stimulated an important and fascinating comparison of numerical modeling codes and tables with experiment. In addition, we participated in developing the FRCHX experiment to compress a field-reversed-configuration (FRC) plasma with a liner, in collaboration with researchers from Air Force Research Laboratory and Los Alamos National Lab, and we helped develop diagnostics for the Plasma Liner Experiment (PLX) at LANL. Last, but not least, this project served to train students in high-energy-density physics.

Generation of shock fronts in the interaction of the short pulses of intense laser light in supercritical plasma

International Nuclear Information System (INIS)

Lopez V, V.E.

2004-01-01

The plasma is the state of the matter but diffused in the nature. The sun and the stars big heaps of hot plasma can be considered. The external surface of the terrestrial atmosphere this recovered by a layer of plasma. All gassy discharge (lightning spark arch etc.) this related with the formation of plasma. This way, 99 percent of our environment this formed almost of plasma. It is denominated plasma to the ionized gas in the one which all or most of the atoms have lost one or several of the electrons that belonged him, becoming positive ions and free electrons. In the plasma certain physical characteristics exist as for their behavior like they are the collective movements the quasi neutrality, the Debye length, the uncertainty etc. All these behaviors make that the study of the plasma is complex. For this they exist technical of numeric simulation joined to the technological advance of big computers of more capacity and prosecution speed. The simulation techniques of particles are those where a numeric code is built based on a model or theory of a system that it is wanted to investigate. This way through the simulation the results are compared with those theoretical predictions based on an analytic model. The applications of the physics of the plasma are multiple however we focus ourselves in the interaction laser-plasma. Both finish decades of investigation in the interaction of lasers with plasma they have been carried out in laboratories of Europe, Japan, United States. This studies concern the propagation of intense light laser in dense plasma homogeneous, the radiation absorption in cold plasma and problems related with the generation of suprathermal electrons among others. Other areas of the physics of the plasma-laser interaction that it has been considerable attention is the broadly well-known field as parametric uncertainties induced instabilities by the light and that they include the dispersions for example stimulated Raman and Brillouin being able to

Enhanced cytocompatibility of silver-containing biointerface by constructing nitrogen functionalities

Energy Technology Data Exchange (ETDEWEB)

Zhang, Wei, E-mail: weizhang@mail.ipc.ac.cn [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Liu, Jun [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Wang, Huaiyu [Department of Physics & Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China); Xu, Ying; Wang, Pingli [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Ji, Junhui, E-mail: jhji@mail.ipc.ac.cn [Technical Institute of Physics and Chemistry, Chinese Academy of Sciences, Beijing 100190 (China); Chu, Paul K. [Department of Physics & Materials Science, City University of Hong Kong, Tat Chee Avenue, Kowloon, Hong Kong (China)

2015-09-15

Graphical abstract: Constructing nitrogen functionalities is promising method to enhance cytocompatibility of the biointerface by simultaneous Ag and N{sub 2} plasma modification. - Highlights: • N{sub 2} plasma immersion ion implantation (PIII) treatment generates plenty of nitrogen functionalities on polymer substrate. • N{sub 2} PIII treatment increases surface roughness and hydrophilicity and improves its capability to adsorb protein. • Simultaneous Ag and N{sub 2} plasma modification constructs nitrogen functionalities to enhance cytocompatibility of the biointerface. - Abstract: Silver (Ag) has recently been introduced into polymeric biomedical implants by plasma immersion ion implantation (PIII) to enhance the antibacterial capability. However, Ag ions and nanoparticles can increase the cytotoxicity and inhibit cellular proliferation and the relationship is time- and dose-dependent. In this study, Ag and N{sub 2} PIII is conducted in concert to produce nitrogen functional groups as well as Ag-containing biointerface. In addition to the creation of nitrogen functionalities, the surface roughness and hydrophilicity are improved in favor of protein adsorption. Compared to the biointerface created by Ag PIII only, the nitrogen functionalities generated by N{sub 2} co-PIII do not affect DNA synthesis and the total protein level but evidently enhance cellular adhesion, viability, and proliferation at the biointerface. The modified surface is observed to upregulate the osteogenesis-related marker expression of bone cells in contact. Our findings suggest that dual Ag and N{sub 2} PIII is a desirable technique to enhance both the cytocompatibility and antibacterial capability of medical polymers.

Effect of whole body gamma-irradiation and/or dietary protein deficiency on the levels of plasma non-protein nitrogen and amino acids; plasma and urinary ammonia and urea in desert rodent and albino rats

International Nuclear Information System (INIS)

Roushdy, H.M.; El-Husseini, M.; Saleh, F.

1984-01-01

The effect of gamma-irradiation exposure on the levels of non-protein nitrogen (N.P.N.) and amino acids in plasma; ammonia and urea in plasma and urine was studied in the desert rodent, Psammomys obesus obesus and albino rats subjected to dietary protein deficiency, N.P.N. and amino acids in plasma were shown to increase by irradiation exposure. The effect of radiation on blood ammonia was less marked, but it caused a significant increase in ammonia excretion in urine. Radiation exposure in albino rats caused a marked increase in urea concentration in plasma of animals fed the high protein diet and irradiated at 780 r. In urine, the tested radiation levels caused an initial increase in urea concentration followed by a subsequent decrease. In psammomys, radiation exposure exerted a little effect on the plasma urea level, whereas significant increase in the daily urea excretion was recorded. It seems that urea level in plasma is more stabilized in psammomys than in albino rats

Forest fuel reduces the nitrogen load - calculations of nitrogen flows

International Nuclear Information System (INIS)

Burstroem, F.; Johansson, Jan.

1995-12-01

Nitrogen deposition in Sweden has increased strongly during recent decades, particularly in southern Sweden. Nitrogen appears to be largely accumulated in biomass and in the soil. It is therefore desirable to check the accumulation of nitrogen in the forest. The most suitable way of doing this is to remove more nitrogen-rich biomass from the forest, i.e., increase the removal of felling residues from final fellings and cleanings. An ecological condition for intensive removal of fuel is that the ashes are returned. The critical load for nitrogen, CL(N), indicates the level of nitrogen deposition that the forest can withstand without leading to ecological changes. Today, nitrogen deposition is higher than the CL(N) in almost all of Sweden. CL(N) is calculated in such a manner that nitrogen deposition should largely be balanced by nitrogen losses through harvesting during a forest rotation. The value of CL(N) thus largely depends on how much nitrogen is removed with the harvested biomass. When both stems and felling residues are harvested, the CL(N) is about three times higher than in conventional forestry. The increase is directly related to the amount of nitrogen in the removed biofuel. Use of biofuel also causes a certain amount of nitrogen emissions. From the environmental viewpoint there is no difference between the sources of the nitrogen compounds. An analysis of the entire fuel chain shows that, compared with the amount of nitrogen removed from the forest with the fuel, about 5 % will be emitted as nitrogen oxides or ammonia during combustion, and a further ca 5 % during handling and transports. A net amount of about 90 % of biomass nitrogen is removed from the system and becomes inert nitrogen (N 2 ). 60 refs, 3 figs, 4 tabs, 11 appendices

High excitation of the species in nitrogen–aluminum plasma generated by electron cyclotron resonance microwave discharge of N2 gas and pulsed laser ablation of Al target

International Nuclear Information System (INIS)

Liang, Peipei; Li, Yanli; Cai, Hua; You, Qinghu; Yang, Xu; Huang, Feiling; Sun, Jian; Xu, Ning; Wu, Jiada

2014-01-01

A reactive nitrogen–aluminum plasma generated by electron cyclotron resonance (ECR) microwave discharge of N 2 gas and pulsed laser ablation of an Al target is characterized spectroscopically by time-integrated and time-resolved optical emission spectroscopy (OES). The vibrational and rotational temperatures of N 2 species are determined by spectral simulation. The generated plasma strongly emits radiation from a variety of excited species including ambient nitrogen and ablated aluminum and exhibits unique features in optical emission and temperature evolution compared with the plasmas generated by a pure ECR discharge or by the expansion of the ablation plume. The working N 2 gas is first excited by ECR discharge and the excitation of nitrogen is further enhanced due to the fast expansion of the aluminum plume induced by target ablation, while the excitation of the ablated aluminum is prolonged during the plume expansion in the ECR nitrogen plasma, resulting in the formation of strongly reactive nitrogen–aluminum plasma which contains highly excited species with high vibrational and rotational temperatures. The enhanced intensities and the prolonged duration of the optical emissions of the combined plasma would provide an improved analytical capability for spectrochemical analysis. - Highlights: • ECR discharge and pulsed laser ablation generate highly excited ECR–PLA plasma. • The expansion of PLA plasma results in excitation enhancement of ECR plasma species. • The ECR plasma leads to excitation prolongation of PLA plasma species. • The ECR–PLA plasma emits strong emissions from a variety of excited species. • The ECR–PLA plasma maintains high vibrational–rotational temperatures for a long time

Foliage nitrogen turnover: differences among nitrogen absorbed at different times by Quercus serrata saplings

Science.gov (United States)

Ueda, Miki U.; Mizumachi, Eri; Tokuchi, Naoko

2011-01-01

Background and Aims Nitrogen turnover within plants has been intensively studied to better understand nitrogen use strategies. However, differences among the nitrogen absorbed at different times are not completely understood and the fate of nitrogen absorbed during winter is largely uncharacterized. In the present study, nitrogen absorbed at different times of the year (growing season, winter and previous growing season) was traced, and the within-leaf nitrogen turnover of a temperate deciduous oak Quercus serrata was investigated. Methods The contributions of nitrogen absorbed at the three different times to leaf construction, translocation during the growing season, and the leaf-level resorption efficiency during leaf senescence were compared using 15N. Key Results Winter- and previous growing season-absorbed nitrogen significantly contributed to leaf construction, although the contribution was smaller than that of growing season-absorbed nitrogen. On the other hand, the leaf-level resorption efficiency of winter- and previous growing season-absorbed nitrogen was higher than that of growing season-absorbed nitrogen, suggesting that older nitrogen is better retained in leaves than recently absorbed nitrogen. Conclusions The results demonstrate that nitrogen turnover in leaves varies with nitrogen absorption times. These findings are important for understanding plant nitrogen use strategies and nitrogen cycles in forest ecosystems. PMID:21515608

Variations in plasma wave intensity with distance along the electron foreshock boundary at Venus

Science.gov (United States)

Crawford, G. K.; Strangeway, R. J.; Russell, C. T.

1991-01-01

Plasma waves are observed in the solar wind upstream of the Venus bow shock by the Pioneer Venus Orbiter. These wave signatures occur during periods when the interplanetary magnetic field through the spacecraft position intersects the bow shock, thereby placing the spacecraft in the foreshock region. Wave intensity is analyzed as a function of distance along the electron foreshock boundary. It is found that the peak wave intensity may increase along the foreshock boundary from the tangent point to a maximum value at several Venus radii, then decrease in intensity with subsequent increase in distance. These observations could be associated with the instability process: the instability of the distribution function increasing with distance from the tangent point to saturation at the peak. Thermalization of the beam for distances beyond this point could reduce the distribution function instability resulting in weaker wave signatures.

Laser induced aluminiun plasma analysis by optical emission spectroscopy in a nitrogen background gas

International Nuclear Information System (INIS)

Chamorro, J C; Uzuriaga, J; Riascos, H

2012-01-01

We studied an Al plasma generated by a Nd:YAG laser with a laser fluence of 4 J/cm 2 , a wavelength of 1064 nm, energy pulse of 500 mJ and 10 Hz repetition rate. We studied their spectral characteristics at various ambient nitrogen pressures by optical emission spectroscopy (OES). The N 2 gas pressure was varied from 20 mTorr to 150 mTorr. In Al plume, both atomic and ionic spectra were observed. The electron temperature and electron number density of the plume as of the function ambient gas pressure were determined. The electron temperature was calculated by using the Boltzmann-plot method and the number density was calculated considering the stark effect as dominating on the emission lines.

Aluminium Morphological Modification by Nitrogen-Argon Mixture PIII

International Nuclear Information System (INIS)

Munnoz-Castro, A.E.; Valencia Alvarado, R.; Penna-Eguiluz, R.; Mercado-Cabrera, A.; Barocio, S.R.; Rodriguez-Mendez, B.G.; Lopez-Callejas, R.; Piedad-Beneitez, A. de la

2011-01-01

With incident fluences of ∼ 10 12 atoms/cm 2 aluminium samples have been plasma immersion ion implanted with either pure nitrogen or argon/nitrogen mixtures at temperatures around 450 o C. X-ray diffraction studies have validated the formation of the cubic phase of AlN, in samples treated with both the gas mixtures and pure nitrogen. Likewise, the presence of the hexagonal phase of AlN has been detected when either pure nitrogen or a 70% N/30% Ar mixture have been used. The signature peak of AlN has also been confirmed by the Raman spectroscopy. The maximal microhardness values were found in samples treated with the mixture. The maximal roughness was achieved with the equal part mixture in all cases, although increasing with the implantation pulse width up to a 300 nm peak at 150 μs. The latter critical value remains invariant under the pure nitrogen plasma treatment, provided that implantation periods in the order of 4.5 h are carried out. (author)

Ion Acceleration by Ultra-intense Laser Pulse Interacting with Double-layer Near-critical Density Plasma

International Nuclear Information System (INIS)

Gu, Y. J.; Kong, Q.; Li, X. F.; Yu, Q.; Wang, P. X.; Kawata, S.; Izumiyama, T.; Nagashima, T.; Takano, M.; Barada, D.; Ma, Y. Y.

2016-01-01

A collimated ion beam is generated through the interaction between ultra-intense laser pulse and a double layer plasma. The maximum energy is above 1 GeV and the total charge of high energy protons is about several tens of nC/μm. The double layer plasma is combined with an underdense plasma and a thin overdense one. The wakefield traps and accelerates a bunch of electrons to high energy in the first underdense slab. When the well collimated electron beam accelerated by the wakefield penetrates through the second overdense slab, it enhances target normal sheath acceleration (TNSA) and breakout after-burner (BOA) regimes. The mechanism is simulated and analyzed by 2.5 dimensional Particle-in-cell code. Compared with single target TNSA or BOA, both the acceleration gradient and energy transfer efficiency are higher in the double layer regime. (paper)

Intense lower-hybrid wave penetration and current drive in reactor-grade plasmas

International Nuclear Information System (INIS)

Cohen, R.H.; Rognlien, T.D; Bonoli, P.T.; Porkolab, M.

1990-01-01

Apply lower-hybrid power in short, intense pulses can overcome Landau damping, allowing penetration into the core of reactor-grade plasmas. We present a theoretical description of the absorption and parametric stability of the pulses, and show results of ray-tracing calculations which include the absorption calculation. Consideration of the absorption and potential source availability lead to the consideration of 5--10 GW peak power, 30--100 μs pulses for ITER, and ∼ 2 MW, 20 μs pulses for a proof-of-principle experiment in the Microwave Tokamak Experiment (MTX)

Intense lower-hybrid wave penetration and current drive in reactor-grade plasmas

Energy Technology Data Exchange (ETDEWEB)

Cohen, R.H.; Rognlien, T.D (Lawrence Livermore National Lab., CA (USA)); Bonoli, P.T.; Porkolab, M. (Massachusetts Inst. of Tech., Cambridge, MA (USA). Plasma Fusion Center)

1990-01-01

Apply lower-hybrid power in short, intense pulses can overcome Landau damping, allowing penetration into the core of reactor-grade plasmas. We present a theoretical description of the absorption and parametric stability of the pulses, and show results of ray-tracing calculations which include the absorption calculation. Consideration of the absorption and potential source availability lead to the consideration of 5--10 GW peak power, 30--100 {mu}s pulses for ITER, and {approximately} 2 MW, 20 {mu}s pulses for a proof-of-principle experiment in the Microwave Tokamak Experiment (MTX).

Oxygen reduction reaction properties of nitrogen-incorporated nanographenes synthesized using in-liquid plasma from mixture of ethanol and iron phthalocyanine

Science.gov (United States)

Amano, Tomoki; Kondo, Hiroki; Takeda, Keigo; Ishikawa, Kenji; Hiramatsu, Mineo; Sekine, Makoto; Hori, Masaru

2018-04-01

Nanographenes were synthesized using in-liquid plasma from a mixture of iron phthalocyanine and ethanol. In a previous study, micrometer-scale flakes with nitrogen incorporation were obtained. A nonprecious metal catalytic activity was observed with 3.13 electrons in an oxygen reduction reaction under an acidic solute condition. Large-surface-area, high-graphene-crystallinity, and iron-carbon-bonding sites were found owing to a high catalytic activity in Fe-N/nanographene.

Erythropoietin does not reduce plasma lactate, H+, and K+ during intense exercise

DEFF Research Database (Denmark)

Nordsborg, Nikolai Baastrup; Robach, P; Boushel, R

2015-01-01

It is investigated if recombinant human erythropoietin (rHuEPO) treatment for 15 weeks (n = 8) reduces extracellular accumulation of metabolic stress markers such as lactate, H(+) , and K(+) during incremental exhaustive exercise. After rHuEPO treatment, normalization of blood volume...... and composition by hemodilution preceded an additional incremental test. Group averages were calculated for an exercise intensity ∼80% of pre-rHuEPO peak power output. After rHuEPO treatment, leg lactate release to the plasma compartment was similar to before (4.3 ± 1.6 vs 3.9 ± 2.5 mmol/min) and remained similar...... after hemodilution. Venous lactate concentration was higher (P release to the plasma compartment after rHuEPO was similar to before (19.6 ± 5.4 vs 17.6 ± 6.0 mmol/min) and remained similar after hemodilution. Nevertheless, venous p...

Equation for calculation of nitrogen solubility in iron alloys

International Nuclear Information System (INIS)

Pomarin, Yu.M.; Grigorenko, G.M.

1989-01-01

Equation for calculating nitrogen solubility in multicomponent iron melts in a wide range of partial pressures (1-1600 kPa), of doping component concentrations and temperatures (1773-2373 K) is proposed. Comparative analysis of experimental and calculated values of nitrogen solubility has demonstrated a principle possibility of applying the equation proposed for evaluating absorption ability to nitrogen of industrial nitrogen containing steels and ferroalloys subjected to melting or remelting in plasma or other melting devices

The Effects of Combination of High Intensity Intermittent Exercise and Supplement Flaxseed Oil 1 ICAM- Plasma Concentration in Male Rats

Directory of Open Access Journals (Sweden)

Y Khademi

2017-01-01

Full Text Available Introduction: Prevalence of cardiovascular diseases is rooted in inflammation and inflammation is along with the increase of ICAM-1. The aim of the present study was to review the effect of combination of high interval training and flaxseed oil supplementation on plasma concentration of ICAM-1 of rats. Methods: In this experimental study, 30 rats were selected and divided into six groups of five male rats, including (1 control, (2 training, (3 10 mg/kg Flaxseed oil, (4 30 mg/kg Flaxseed oil, (5 training with 10 mg/kg Flaxseed oil and (6 training with 30 mg/kg Flaxseed oil. Groups of 2, 5 and 6 were trained with high intensity interval training for 10 weeks and five sessions per week, also groups 3 to 6 received flaxseed oil for 10 weeks. For statistical analysis of data two way ANOVA test was used (p≤0.05. Results: 10 weeks  treating high intensity interval training  for 10 weeks had significant effect on the increase of the plasma concentration of ICAM-1 of male rats (p=0.001. Nevertheless, Taking 10 weeks 10 and 30 mg/kg flaxseed oil supplementation for 10 weeks has significant effect on reducing  the plasma concentration of ICAM-1 of rats (p=0.001. Training and taking flaxseed oil supplementation have interactional effect on reduingc the plasma concentration of ICAM-1 of male rats (p=0.001. Conclusion: Combination of high intensity interval training and flaxseed oil supplementation has interactional effects on the improvement of plasma concentration of ICAM-1 in male rats.

Synthesis of high Al content AlxGa1−xN ternary films by pulsed laser co-ablation of GaAs and Al targets assisted by nitrogen plasma

International Nuclear Information System (INIS)

Cai, Hua; You, Qinghu; Hu, Zhigao; Guo, Shuang; Yang, Xu; Sun, Jian; Xu, Ning; Wu, Jiada

2014-01-01

Highlights: • Al x Ga 1−x N films were synthesized by co-ablation of an Al target and a GaAs target. • Nitrogen plasma was used to assist the synthesis of Al x Ga 1−x N ternary films. • The Al x Ga 1−x N films are slightly rich in N with an Al content above 0.6. • The Al x Ga 1−x N films are hexagonal wurtzite in crystal structure. • The Al x Ga 1−x N films have an absorption edge of 260 nm and a band gap of 4.7 eV. - Abstract: We present the synthesis of Al x Ga 1−x N ternary films by pulsed laser co-ablation of a polycrystalline GaAs target and a metallic Al target in the environment of nitrogen plasma which provides nitrogen for the films and assists the formation of nitride films. Field emission scanning electron microscopy exposes the smooth surface appearance and dense film structure. X-ray diffraction, Fourier-transform infrared spectroscopy and Raman scattering spectroscopy reveal the hexagonal wurtzite structure. Optical characterization shows high optical transmittance with an absorption edge of about 260 nm and a band gap of 4.7 eV. Compositional analysis gives the Al content of about 0.6. The structure and optical properties of the Al x Ga 1−x N films are compared with those of binary GaN and AlN films synthesized by ablating GaAs or Al target with the same nitrogen plasma assistance

Characteristics of ion spectrum in a low energy nitrogen operated plasma focus: application to the metallic substrates thermal treatment

International Nuclear Information System (INIS)

Kelly, H.; Lepone, A.; Marquez, A.

1998-01-01

Full text: This work presents the nitrogen ion spectrum characteristics in a Plasma Focus device, determined using a Thomson spectrometer and a Faraday cup, operated in the secondary electron collective mode. It is also discussed the thermal treatment and the re coating induce by ions incident on a metallic surface (AISI 304 steel) placed in front of the coaxial gun, when the device is operated with a Ti implant at the end of the central electrode

Diagnostics of N{sub 2}-Ar plasma mixture excited in a 13.56 MHz hollow cathode discharge system: application to remote plasma treatment of polyamide surface

Energy Technology Data Exchange (ETDEWEB)

Saloum, S; Naddaf, M; Alkhaled, B [Atomic Energy Commission of Syria (AECS), Physics Department, PO Box 6091, Damascus (Syrian Arab Republic)], E-mail: scientific@aec.org.sy

2008-02-21

N{sub 2}-x% Ar plasma gas mixture, generated in a hollow cathode RF discharge system, has been characterized by both optical emission spectroscopy (OES) and double Langmuir probe, as a function of experimental parameters: total pressure (5-33 Pa), and different fractions of argon (7 {<=} x {<=} 80), at a constant applied RF power of 300 W. N{sub 2} dissociation degree has been investigated qualitatively by both the actinometry method and the ratio I{sub N}/I{sub N{sub 2}} of the atomic nitrogen line emission intensity at 672.3 nm to the vibrational band (0-0) of the N{sub 2} second positive system at 337.1 nm. Both methods showed that the increase in argon fraction enhances the dissociation of N{sub 2}, with a maximum at x = 50 for the pressure of 5 Pa, although the two methods give two opposite trends as a function of total pressure. Spectroscopic measurements showed that the vibrational temperature of the N{sub 2} second positive system increases with both argon fraction and total pressure increase, it lies between 4900 and 12 300 K. Langmuir probe measurements showed that, in the remote zone, the electron temperature falls in the range 1.57-1.75 eV, the N{sub 2}{sup +} density varies between 5 x 10{sup 9} and 1.4 x 10{sup 10} cm{sup -3} and that both the plasma ionization degree and electron temperature increase towards the source. In addition, the process of plasma-polyamide (PA) surface interaction, in the remote plasma zone, has been studied through OES analysis during plasma treatment of PA to monitor the possible emissions due to the polymer etching. An increase in atomic nitrogen line (672.3 nm) intensity is obtained, atomic carbon line (833.52 nm) and the band emission (0-0) from the CN (B {sup 2}{sigma}{sup +}-X {sup 2}{sigma}{sup +}) violet system were observed. The PA surface modification has been confirmed through the improvement of its hydrophilic character as the water contact angle measured after the plasma treatment significantly decreased.

Interaction of intense laser pulses with neutral gases and preformed plasmas

International Nuclear Information System (INIS)

Mackinnon, A. J.; Borghesi, M.; Iwase, A.; Jones, M. W.; Willi, O.

1998-01-01

The interaction of a high intensity laser pulse with a neutral gas or preformed plasma has been studied over a wide range of target and laser conditions. It was found that the propagation of 2ps laser pulses (λ=1.054μm, P=5-10TW, I∼5x10 14 -1x10 14 -1x10 18 Wcm -2 ) in neutral gases with atomic densities greater than 0.001 of critical was strongly influenced by ionisation induced refraction. Preformed density channels were effective in overcoming refraction but the channel length was found to be limited by ionization induced defocusing of the prepulse

Spectrum of harmonic emission by inhomogeneous plasma in intense electromagnetic wave

International Nuclear Information System (INIS)

Kovalev, V.F.; Pustovalov, V.V.

1989-01-01

The spectrum and angular distribution of the harmonics of arbitrary index emitted by a cold, inhomogeneous electron plasma subjected to a p-polarized electromagnetic wave have been studied analytically. The results are shown in graphical form. The intensity of the wave was varied over a wide range. At energy flux densities of the electromagnetic wave at which the inverse effect of the higher harmonics on the lower harmonics becomes appreciable, it becomes possible to observe a decay of the absolute value of the complex amplitude of a harmonic with increasing harmonic index in vacuum which is substantially slower than that predicted by the theory for a weak nonlinearity

Special issue: Plasma Conversion

NARCIS (Netherlands)

Nozaki, T.; Bogaerts, A.; Tu, X.; van de Sanden, M. C. M.

2017-01-01

With growing concern of energy and environmental issues, the combination of plasma and heterogeneous catalysts receives special attention in greenhouse gas conversion, nitrogen fixation and hydrocarbon chemistry. Plasma gas conversion driven by renewable electricity is particularly important for the

Study on re-sputtering during CN{sub x} film deposition through spectroscopic diagnostics of plasma

Energy Technology Data Exchange (ETDEWEB)

Liang, Peipei; Yang, Xu; Li, Hui; Cai, Hua [Department of Optical Science and Engineering, Fudan University, Shanghai 200433 (China); Sun, Jian; Xu, Ning [Department of Optical Science and Engineering, Fudan University, Shanghai 200433 (China); Shanghai Engineering Research Center of Ultra-Precision Optical Manufacturing, Fudan University, Shanghai 200433 (China); Wu, Jiada, E-mail: jdwu@fudan.edu.cn [Department of Optical Science and Engineering, Fudan University, Shanghai 200433 (China); Shanghai Engineering Research Center of Ultra-Precision Optical Manufacturing, Fudan University, Shanghai 200433 (China); Engineering Research Center of Advanced Lighting Technology, Ministry of Education, Fudan University, Shanghai 200433 (China)

2015-10-15

A nitrogen-carbon plasma was generated during the deposition of carbon nitride (CN{sub x}) thin films by pulsed laser ablation of a graphite target in a discharge nitrogen plasma, and the optical emission of the generated nitrogen-carbon plasma was measured for the diagnostics of the plasma and the characterization of the process of CN{sub x} film deposition. The nitrogen-carbon plasma was recognized to contain various species including nitrogen molecules and molecular ions excited in the ambient N{sub 2} gas, carbon atoms and atomic ions ablated from the graphite target and CN radicals. The temporal evolution and spatial distribution of the CN emission and their dependence on the substrate bias voltage show two groups of CN radicals flying in opposite directions. One represents the CN radicals formed as the products of the reactions occurring in the nitrogen-carbon plasma, revealing the reactive deposition of CN{sub x} film due to the reactive expansion of the ablation carbon plasma in the discharge nitrogen plasma and the effective formation of gaseous CN radicals as precursors for CN{sub x} film growth. The other one represents the CN radicals re-sputtered from the growing CN{sub x} film by energetic plasma species, evidencing the re-sputtering of the growing film accompanying film growth. And, the re-sputtering presents ion-induced sputtering features.

Analysis of the tuning characteristics of microwave plasma source

International Nuclear Information System (INIS)

Miotk, Robert; Jasiński, Mariusz; Mizeraczyk, Jerzy

2016-01-01

In this paper, we present an analysis of the tuning characteristics of waveguide-supplied metal-cylinder-based nozzleless microwave plasma source. This analysis has enabled to estimate the electron concentration n_e and electron frequency collisions ν in the plasma generated in nitrogen and in a mixture of nitrogen and ethanol vapour. The parameters n_e and ν are the basic quantities that characterize the plasma. The presented new plasma diagnostic method is particularly useful, when spectroscopic methods are useless. The presented plasma source is currently used in research of a hydrogen production from liquids.

Preparation of a liquid nitrogen target for measurement of γ-ray in the 14N(n,γ)15N reaction as an intensity standard in energy region up to 11 MeV

International Nuclear Information System (INIS)

Hirano, M.; Obayashi, H.; Sakane, H.; Shibata, M.; Kawade, K.; Taniguchi, A.

2001-01-01

For determination of relative γ-ray intensities up to 11 MeV in the 14 N(n,γ) 15 N reaction, we have developed a liquid nitrogen (N 2 ) target which contain no hydrogen (H) to improve the accuracy of γ-ray intensities. The ratio of the relative uncertainties for the liquid nitrogen to that for the melamine (C 3 H 6 N 6 ) widely used was improved by a factor of 2 above 2.2 MeV and a factor of 3 - 6 below 2.2 MeV. It has been shown that the liquid nitrogen target is useful for reduction of the 2.2 MeV γ-ray from the 1 H(n,γ) 2 H reaction and improvement of statistics. (author)

Tribological behavior of plasma-polymerized aminopropyltriethoxysilane films deposited on thermoplastic elastomers substrates

Energy Technology Data Exchange (ETDEWEB)

Alba-Elías, Fernando, E-mail: fernando.alba@unirioja.es [Department of Mechanical Engineering, University of La Rioja, c/Luis de Ulloa 20, 26004 Logroño, La Rioja (Spain); Sainz-García, Elisa; González-Marcos, Ana [Department of Mechanical Engineering, University of La Rioja, c/Luis de Ulloa 20, 26004 Logroño, La Rioja (Spain); Ordieres-Meré, Joaquín [ETSII, Polytechnic University of Madrid, c/José Gutiérrez Abascal 2, 28006 Madrid (Spain)

2013-07-01

Thermoplastic elastomers (TPE) are multifunctional polymeric materials that are characterized by moderate cost, excellent mechanical properties (high elasticity, good flexibility, hardness, etc.), high tensile strength, oxidation and wettability. With an objective of reducing the superficial friction coefficient of TPE, this work analyzes the characteristics of coating films that are based on aminopropyltriethoxysilane (APTES) over a TPE substrate. Since this material is heat-sensitive, it is necessary to use a technology that permits the deposition of coatings at low temperatures without affecting the substrate integrity. Thus, an atmospheric-pressure plasma jet system (APPJ) with a dielectric barrier discharge (DBD) was used in this study. The coated samples were analyzed by Scanning Electron Microscopy, Atomic Force Microscopy, Fourier-Transform Infrared with Attenuated Total Reflectance Spectroscopy, X-ray Photoelectron Spectroscopy and tribological tests (friction coefficient and wear rate). The studies showed that the coated samples that contain a higher amount of forms of silicon (SiOSi) and nitrogen (amines, amides and imines) have lower friction coefficients. The sample coated at a specific plasma power of 550 W and an APTES flow rate of 1.5 slm had the highest values of SiOSi and nitrogen-containing groups peak intensity and atomic percentages of Si2p and SiO{sub 4}, and the lowest percentages of C1s and average friction coefficient. The results of this research permit one to conclude that APPJ with a DBD is a promising technique to use in coating SiO{sub x} and nitrogen-containing groups layers on polymeric materials. - Highlights: • SiO{sub x} thin films on thermoplastic elastomers by atmospheric pressure plasma jet. • Study of influence of plasma power and precursor flow rate on film's properties. • Friction coefficient is inversely related to the amount of SiOSi and N groups. • Nitrogen groups from the ionization gas (N{sub 2}) seem to

Absolute atomic oxygen and nitrogen densities in radio-frequency driven atmospheric pressure cold plasmas: Synchrotron vacuum ultra-violet high-resolution Fourier-transform absorption measurements

International Nuclear Information System (INIS)

Niemi, K.; O'Connell, D.; Gans, T.; Oliveira, N. de; Joyeux, D.; Nahon, L.; Booth, J. P.

2013-01-01

Reactive atomic species play a key role in emerging cold atmospheric pressure plasma applications, in particular, in plasma medicine. Absolute densities of atomic oxygen and atomic nitrogen were measured in a radio-frequency driven non-equilibrium plasma operated at atmospheric pressure using vacuum ultra-violet (VUV) absorption spectroscopy. The experiment was conducted on the DESIRS synchrotron beamline using a unique VUV Fourier-transform spectrometer. Measurements were carried out in plasmas operated in helium with air-like N 2 /O 2 (4:1) admixtures. A maximum in the O-atom concentration of (9.1 ± 0.7)×10 20 m −3 was found at admixtures of 0.35 vol. %, while the N-atom concentration exhibits a maximum of (5.7 ± 0.4)×10 19 m −3 at 0.1 vol. %

Plasma properties during magnetron sputtering of lithium phosphorous oxynitride thin films

DEFF Research Database (Denmark)

Christiansen, Ane Sælland; Stamate, Eugen; Thydén, Karl Tor Sune

2015-01-01

The nitrogen dissociation and plasma parameters during radio frequency sputtering of lithium phosphorus oxynitride thin films in nitrogen gas are investigated by mass appearance spectrometry, electrostatic probes and optical emission spectroscopy, and the results are correlated with electrochemical...... properties and microstructure of the films. Low pressure and moderate power are associated with lower plasma density, higher electron temperature, higher plasma potential and larger diffusion length for sputtered particles. This combination of parameters favors the presence of more atomic nitrogen, a fact...

Sterilization and decontamination of medical instruments by low-pressure plasma discharges: application of Ar/O2/N2 ternary mixture

International Nuclear Information System (INIS)

Kylian, O; Rossi, F

2009-01-01

A low-pressure inductively coupled plasma discharge sustained in an argon-oxygen-nitrogen ternary mixture is studied in order to evaluate its properties in terms of sterilization and decontamination of surfaces of medical instruments. It is demonstrated by direct comparison with discharges operated in oxygen-nitrogen and oxygen-argon mixtures that application of an Ar/O 2 /N 2 mixture offers the possibility to combine advantageous properties of the binary mixtures, namely, the capability of an O 2 /N 2 plasma to emit intense UV radiation needed for effective inactivation of bacterial spores together with high removal rates of biological substances from Ar/O 2 discharge. Moreover, optimal conditions for both effects are obtained at a similar ternary discharge mixture composition, which is of much interest for real applications, since it offers a highly effective process desired for the safety of medical instruments.

Deposition of silicon films in presence of nitrogen plasma— A ...

Indian Academy of Sciences (India)

Unknown

Abstract. A design, development and validation work of plasma based 'activated reactive evaporation (ARE) system' is implemented for the deposition of the silicon films in presence of nitrogen plasma on substrate maintained at room temperature. This plasma based deposition system involves evaporation of pure silicon by.

Resonant heating of a cluster plasma by intense laser light

International Nuclear Information System (INIS)

Antonsen, Thomas M. Jr.; Taguchi, Toshihiro; Gupta, Ayush; Palastro, John; Milchberg, Howard M.

2005-01-01

Gases of atomic clusters are interaction media for laser pulse propagation with properties useful for applications such as extreme ultraviolet (EUV) and x-ray microscopy, harmonic generation, EUV lithography, and laser plasma acceleration. To understand cluster heating and expansion, a series of two- and three-dimensional electrostatic particle in cell simulations of the explosion of argon clusters of diameter in the range 20 nm-53 nm have been preformed. The studies show that heating is dominated by a nonlinear, resonant absorption process that gives rise to a size-dependent intensity threshold for strong absorption and that controls the dielectric properties of the cluster. Electrons are first accelerated out from the cluster and then driven back into it by the combined effects of the laser field and the electrostatic field produced by the laser-driven charge separation. Above the intensity threshold for strong heating there is a dramatic increase in the production of energetic particles and harmonic radiation. The dielectric properties of a gas of clusters are determined by the ensemble average cluster polarizability. Individual electrons contribute to the polarizability differently depending on whether they are in the core of the cluster or in the outer edge. Consequently, there can be large fluctuations in polarizability during the heating of a cluster

Production of nitrogen containing chemicals from cyanophycin

NARCIS (Netherlands)

Könst, P.M.

2011-01-01

Currently nitrogen containing bulk chemicals are produced from naphtha. However, as explained in Chapter 1 it would be more energy efficient, less capital intensive and eventually more economical to start from functionalized compounds that already have nitrogen incorporated, such as amino

Analysis of nitrogen species in titanium oxynitride ALD films

Energy Technology Data Exchange (ETDEWEB)

Sowińska, Małgorzata, E-mail: Malgorzata.Sowinska@b-tu.de [Brandenburgische Technische Universität Cottbus-Senftenberg, Angewandte Physik-Sensorik, Konrad-Wachsmann-Allee 17, 03046 Cottbus (Germany); Brizzi, Simone; Das, Chittaranjan [Brandenburgische Technische Universität Cottbus-Senftenberg, Angewandte Physik-Sensorik, Konrad-Wachsmann-Allee 17, 03046 Cottbus (Germany); Kärkkänen, Irina; Schneidewind, Jessica; Naumann, Franziska; Gargouri, Hassan [SENTECH Instruments GmbH, Schwarzschildstraße 2, 12489 Berlin (Germany); Henkel, Karsten; Schmeißer, Dieter [Brandenburgische Technische Universität Cottbus-Senftenberg, Angewandte Physik-Sensorik, Konrad-Wachsmann-Allee 17, 03046 Cottbus (Germany)

2016-09-15

Titanium oxynitride films are prepared by plasma enhanced atomic layer deposition method using two different precursors and nitrogen sources. Synchrotron radiation-based X-ray photoelectron spectroscopy and X-ray absorption spectroscopy are used to characterize the nitrogen species incorporated within these films depending on the deposition parameters. It is found that nitrogen atoms in these films are differently bonded. In particular, it can be distinguished between Ti−ON and Ti−N bonding configurations and molecular nitrogen species caused by precursor fragments.

The nitrogen cascade from agricultural soils to the sea: modelling nitrogen transfers at regional watershed and global scales

OpenAIRE

Billen, Gilles; Garnier, Josette; Lassaletta, Luis

2013-01-01

The nitrogen cycle of pre-industrial ecosystems has long been remarkably closed, in spite of the high mobility of this element in the atmosphere and hydrosphere. Inter-regional and international commercial exchanges of agricultural goods, which considerably increased after the generalization of the use of synthetic nitrogen fertilizers, introduced an additional type of nitrogen mobility, which nowadays rivals the atmospheric and hydrological fluxes in intensity, and causes their enhancement a...

Analysis of the tuning characteristics of microwave plasma source

Energy Technology Data Exchange (ETDEWEB)

Miotk, Robert, E-mail: rmiotk@imp.gda.pl; Jasiński, Mariusz [Centre for Plasma and Laser Engineering, The Szewalski Institute of Fluid-Flow Machinery, Polish Academy of Sciences, Fiszera 14, 80-231 Gdańsk (Poland); Mizeraczyk, Jerzy [Department of Marine Electronics, Gdynia Maritime University, Morska 81-87, 81-225 Gdynia (Poland)

2016-04-15

In this paper, we present an analysis of the tuning characteristics of waveguide-supplied metal-cylinder-based nozzleless microwave plasma source. This analysis has enabled to estimate the electron concentration n{sub e} and electron frequency collisions ν in the plasma generated in nitrogen and in a mixture of nitrogen and ethanol vapour. The parameters n{sub e} and ν are the basic quantities that characterize the plasma. The presented new plasma diagnostic method is particularly useful, when spectroscopic methods are useless. The presented plasma source is currently used in research of a hydrogen production from liquids.

The effect of nitrogen and oxygen plasma on the wear properties and adhesion strength of the diamond-like carbon film coated on PTFE

International Nuclear Information System (INIS)

Ozeki, K.; Hirakuri, K.K.

2008-01-01

Diamond-like carbon (DLC) films were deposited on polytetrafluoroethylene (PTFE) using a radiofrequency plasma chemical vapour deposition method. Prior to DLC coating, the PTFE substrates were modified with O 2 and N 2 plasma to enhance the adhesion strength of the DLC film to the substrate. The effect of the plasma pre-treatment on the chemical composition and the surface energy of the plasma pre-treated PTFE surface was investigated by X-ray photoelectron spectroscopy (XPS) and static water contact angle measurement, respectively. A pull-out test and a ball-on-disc test were carried out to evaluate the adhesion strength and the wear properties of the DLC-coated PTFE. In the N 2 plasma pre-treatment, the XPS result indicated that defluorination and the nitrogen grafting occurred on the plasma pre-treated PTFE surface, and the water contact angle decreased with increasing the plasma pre-treatment time. In the O 2 plasma pre-treatment, no grafting of the oxygen occurred, and the water contact angle slightly increased with the treatment time. In the pull-out test, the adhesion strength of the DLC film to the PTFE substrate was improved with the plasma pre-treatment to the PTFE substrate, and N 2 plasma pre-treatment was more effective than the O 2 plasma pre-treatment. In the ball-on-disc test, the DLC film with the N 2 plasma pre-treatment showed good wear resistance, compared with that with O 2 plasma pre-treatment

Plasma Wakefield Acceleration of an Intense Positron Beam

Energy Technology Data Exchange (ETDEWEB)

Blue, B

2004-04-21

The Plasma Wakefield Accelerator (PWFA) is an advanced accelerator concept which possess a high acceleration gradient and a long interaction length for accelerating both electrons and positrons. Although electron beam-plasma interactions have been extensively studied in connection with the PWFA, very little work has been done with respect to positron beam-plasma interactions. This dissertation addresses three issues relating to a positron beam driven plasma wakefield accelerator. These issues are (a) the suitability of employing a positron drive bunch to excite a wake; (b) the transverse stability of the drive bunch; and (c) the acceleration of positrons by the plasma wake that is driven by a positron bunch. These three issues are explored first through computer simulations and then through experiments. First, a theory is developed on the impulse response of plasma to a short drive beam which is valid for small perturbations to the plasma density. This is followed up with several particle-in-cell (PIC) simulations which study the experimental parameter (bunch length, charge, radius, and plasma density) range. Next, the experimental setup is described with an emphasis on the equipment used to measure the longitudinal energy variations of the positron beam. Then, the transverse dynamics of a positron beam in a plasma are described. Special attention is given to the way focusing, defocusing, and a tilted beam would appear to be energy variations as viewed on our diagnostics. Finally, the energy dynamics imparted on a 730 {micro}m long, 40 {micro}m radius, 28.5 GeV positron beam with 1.2 x 10{sup 10} particles in a 1.4 meter long 0-2 x 10{sup 14} e{sup -}/cm{sup 3} plasma is described. First the energy loss was measured as a function of plasma density and the measurements are compared to theory. Then, an energy gain of 79 {+-} 15 MeV is shown. This is the first demonstration of energy gain of a positron beam in a plasma and it is in good agreement with the predictions

Investigation of a measure of robustness in inductively coupled plasma mass spectrometry

Science.gov (United States)

Makonnen, Yoseif; Beauchemin, Diane

2015-01-01

In industrial/commercial settings where operators often have minimal expertise in inductively coupled plasma (ICP) mass spectrometry (MS), there is a prevalent need for a response factor indicating robust plasma conditions, which is analogous to the Mg II/Mg I ratio in ICP optical emission spectrometry (OES), whereby a Mg II/Mg I ratio of 10 constitutes robust conditions. While minimizing the oxide ratio usually corresponds to robust conditions, there is no specific target value that is widely accepted as indicating robust conditions. Furthermore, tuning for low oxide ratios does not necessarily guarantee minimal matrix effects, as they really address polyatomic interferences. From experiments, conducted in parallel for both MS and OES, there were some element pairs of similar mass and very different ionization potential that were exploited for such a purpose, the rationale being that, if these elements were ionized to the same extent, then that could be indicative of a robust plasma. The Be II/Li I intensity ratio was directly related to the Mg II/Mg I ratio in OES. Moreover, the 9Be+/7Li+ ratio was inversely related to the CeO+/Ce+ and LaO+/La+ oxide ratios in MS. The effects of different matrices (i.e. 0.01-0.1 M Na) were also investigated and compared to a conventional argon plasma optimized for maximum sensitivity. The suppression effect of these matrices was significantly reduced, if not eliminated in the case of 0.01 M Na, when the 9Be+/7Li+ ratio was around 0.30 on the Varian 820 MS instrument. Moreover, a very similar ratio (0.28) increased robustness to the same extent on a completely different ICP-MS instrument (PerkinElmer NEXION). Much greater robustness was achieved using a mixed-gas plasma with nitrogen in the outer gas and either nitrogen or hydrogen as a sheathing gas, as the 9Be+/7Li+ ratio was then around 1.70. To the best of our knowledge, this is the first report on using a simple analyte intensity ratio, 9Be+/7Li+, to gauge plasma robustness.

Inductively coupled plasma as atomization, excitation and ionization sources in analytical atomic spectrometry

International Nuclear Information System (INIS)

Kawaguchi, Hiroshi

1996-01-01

Studies on inductively coupled plasma (ICP) for atomic emission and mass spectrometry accomplished in our laboratory since 1978 are reviewed. In emission spectrometry, the characteristics of the plasma are studied concerning the spatial profiles of spectral line intensity, axial profiles of gas and excitation temperatures, spectral line widths and matrix effect. The studies are particularly emphasized on the instrumentation such as developments of plasma generator, emission spectrometers, water-cooled torches and sample introduction methods. A slew-scan type spectrometer developed in these works represents a predecessor of the current commercial spectrometers. An ICP mass spectrometer was first developed in Japan in this laboratory in 1984. Non-spectroscopic interference of this method was found to have the correlation with the atomic weight of the matrix element. Plasma gases other than argon such as nitrogen and oxygen were used for the ICP to evaluate their performance in mass spectrometry as for the sensitivity and interferences. (author). 63 refs

A Planar Source of Atmospheric-Pressure Plasma Jet

Science.gov (United States)

Zhdanova, O. S.; Kuznetsov, V. S.; Panarin, V. A.; Skakun, V. S.; Sosnin, E. A.; Tarasenko, V. F.

2018-01-01

In a single-barrier discharge with voltage sharpening and low gas consumption (up to 1 L/min), plane atmospheric pressure plasma jets with a width of up to 3 cm and length of up to 4 cm in air are formed in the slit geometry of the discharge zone. The energy, temperature, and spectral characteristics of the obtained jets have been measured. The radiation spectrum contains intense maxima corresponding to vibrational transitions of the second positive system of molecular nitrogen N2 ( C 3Π u → B 3Π g ) and comparatively weak transition lines of the first positive system of the N 2 + ion ( B 2Σ u + → X 2Σ g ). By an example of inactivation of the Staphylococcus aureus culture (strain ATCC 209), it is shown that plasma is a source of chemically active particles providing the inactivation of microorganisms.

The plasma membrane H⁺ -ATPase AHA2 contributes to the root architecture in response to different nitrogen supply

DEFF Research Database (Denmark)

Młodzińska, Ewa; Kłobus, Grażyna; Christensen, Monica Daugbjerg

2015-01-01

of lateral root primordia, root elongation and increase the root biomass. However, the signal transduction mechanisms, which enable roots to sense changes in different mineral environments and match their growth and development patterns to actual conditions in the soil, are still unknown. Most recent...... comments have focused on one of the essential macroelements, namely nitrogen, and its role in the modification of the root architecture of Arabidopsis thaliana. As yet, not all elements of the signal transduction pathway leading to the perception of the nitrate stimulus, and hence to anatomical changes...... of the root, which allow for adaptation to variable ion concentrations in the soil, are known. Our data demonstrate that primary and lateral root length were shorter lower in aha2 mutant lines compared to wild-type plants in response to a variable nitrogen source. This suggests that the plasma membrane proton...

Interferometric analysis of laboratory photoionized plasmas utilizing supersonic gas jet targets.

Science.gov (United States)

Swanson, Kyle James; Ivanov, Vladimir; Mancini, Roberto; Mayes, Daniel C.

2018-06-01

Photoionized plasmas are an important component of active galactic nuclei, x-ray binary systems and other astrophysical objects. Laboratory produced photoionized plasmas have mainly been studied at large scale facilities, due to the need for high intensity broadband x-ray flux. Using supersonic gas jets as targets has allowed university scale pulsed power generators to begin similar research. The two main advantages of this approach with supersonic gas jets include: possibility of a closer location to the x-ray source and no attenuation related to material used for containment and or tamping. Due to these factors, this experimental platform creates a laboratory environment that more closely resembles astrophysical environments. This system was developed at the Nevada Terawatt Facility using the 1 MA pulsed power generator Zebra. Neon, argon, and nitrogen supersonic gas jets are produced approximately 7-8mm from the z-pinch axis. The high intensity broadband x-ray flux produced by the collapse of the z-pinch wire array implosion irradiates the gas jet. Cylindrical wire arrays are made with 4 and 8 gold 10µm thick wire. The z-pinch radiates approximately 12-16kj of x-ray energy, with x-ray photons under 1Kev in energy. The photoionized plasma is measured via x-ray absorption spectroscopy and interferometry. A Mach-Zehnder interferometer is used to the measure neutral density of the jet prior to the zebra shot at a wavelength of 266 nm. A dual channel air-wedge shearing interferometer is used to measure electron density of the ionized gas jet during the shot, at wavelengths of 532nm and 266nm. Using a newly developed interferometric analysis tool, average ionization state maps of the plasma can be calculated. Interferometry for nitrogen and argon show an average ionization state in the range of 3-8. Preliminary x-ray absorption spectroscopy collected show neon absorption lines. This work was sponsored in part by DOE Office of Science Grant DE-SC0014451.

Coupled effects of light and nitrogen source on the urea cycle and nitrogen metabolism over a diel cycle in the marine diatom Thalassiosira pseudonana.

Science.gov (United States)

Bender, Sara J; Parker, Micaela S; Armbrust, E Virginia

2012-03-01

Diatoms are photoautotrophic organisms capable of growing on a variety of inorganic and organic nitrogen sources. Discovery of a complete urea cycle in diatoms was surprising, as this pathway commonly functions in heterotrophic organisms to rid cells of waste nitrogen. To determine how the urea cycle is integrated into cellular nitrogen metabolism and energy management, the centric diatom Thalassiosira pseudonana was maintained in semi-continuous batch cultures on nitrate, ammonium, or urea as the sole nitrogen source, under a 16: 8 light: dark cycle and at light intensities that were low, saturating, or high for growth. Steady-state transcript levels were determined for genes encoding enzymes linked to the urea cycle, urea hydrolysis, glutamine synthesis, pyrimidine synthesis, photorespiration, and energy storage. Transcript abundances were significantly affected by nitrogen source, light intensity and a diel cycle. The impact of N source on differential transcript accumulation was most apparent under the highest light intensity. Models of cellular metabolism under high light were developed based on changes in transcript abundance and predicted enzyme localizations. We hypothesize that the urea cycle is integrated into nitrogen metabolism through its connection to glutamine and in the eventual production of urea. These findings have important implications for nitrogen flow in the cell over diel cycles at surface ocean irradiances. Copyright © 2011 Elsevier GmbH. All rights reserved.

Defect-induced Catalysis toward the Oxygen Reduction Reaction in Single-walled Carbon Nanotube: Nitrogen doped and Non-nitrogen doped

International Nuclear Information System (INIS)

Lu, Di; Wu, Dan; Jin, Jian; Chen, Liwei

2016-01-01

Single-walled carbon nanotubes (SWNTs) are post-treated by argon (Ar) or ammonia (NH 3 ) plasma irradiation to introduce defects that are potentially related to catalysis towards the oxygen reduction reaction (ORR). Electrochemical characterization in alkali medium suggests that the plasma irradiated SWNTs demonstrate enhanced catalytic activity toward the ORR with a positively shifted threshold potential. Moreover the enhanced desired four-electron pathway catalytic activity, which exhibited as the positive shifted threshold potential, is independent of the nitrogen dopant. The nature of the defects is probed with Raman and X-ray photoelectron spectroscopy. The results indicate that the non-nitrogen doped defects of SWNTs contribute to the actual active site for the ORR.

Particle-in-cell simulations of high energy electron production by intense laser pulses in underdense plasmas

International Nuclear Information System (INIS)

Susumu, Kato; Eisuke, Miura; Kazuyoshi, Koyama; Mitsumori, Tanimoto; Masahiro, Adachi

2004-01-01

The propagation of intense laser pulses and the generation of high energy electrons from underdense plasmas are investigated using two dimensional particle-in-cell simulations. When the ratio of the laser power to the critical power of relativistic self-focusing gets the optimal value, the laser pulse propagates in a steady way and electrons have maximum energies. (author)

Particle-in-cell simulations of high energy electron production by intense laser pulses in underdense plasmas

Energy Technology Data Exchange (ETDEWEB)

Susumu, Kato; Eisuke, Miura; Kazuyoshi, Koyama [National Institute of Advanced Industrial Science and Technology (AIST), Tsukuba, Ibaraki (Japan); Mitsumori, Tanimoto [Meisei Univ., Dept. of Electrical Engineering, Hino, Tokyo (Japan); Masahiro, Adachi [Hiroshima Univ., Graduate school of Advanced Science of Matter, Higashi-Hiroshima, Hiroshima (Japan)

2004-07-01

The propagation of intense laser pulses and the generation of high energy electrons from underdense plasmas are investigated using two dimensional particle-in-cell simulations. When the ratio of the laser power to the critical power of relativistic self-focusing gets the optimal value, the laser pulse propagates in a steady way and electrons have maximum energies. (author)

Influence of inlet concentration and light intensity on the photocatalytic oxidation of nitrogen(II) oxide at the surface of Aeroxide® TiO2 P25

International Nuclear Information System (INIS)

Dillert, Ralf; Stötzner, Julia; Engel, Astrid; Bahnemann, Detlef W.

2012-01-01

Highlights: ► The photocatalytic oxidation of nitrogen(II) oxide at the TiO 2 surface was studied. ► The effect of the UV(A) light intensity on the reaction rate was evaluated. ► The effect of the NO concentration on the reaction rate was evaluated. ► A mechanistic model for the heterogeneous NO oxidation is presented. ► A rate law describing the influence of NO concentration and light intensity is given. - Abstract: Air pollution by nitrogen oxides represents a serious environmental problem in urban areas where numerous sources of these pollutants are concentrated. One approach to reduce the concentration of these air pollutants is the light-induced oxidation in the presence of molecular oxygen and a photocatalytically active building material, e.g., paints, roof tiles, or pavement stones. Herein, results of an investigation concerning the photocatalytic oxidation of nitrogen(II) oxide (NO) in the presence of molecular oxygen and UV(A) irradiated TiO 2 powder are presented. The standard operating procedure described in ISO 22197-1 which was developed to characterize the photocatalytic activity of air-cleaning products was successfully applied to determine the photocatalytic activity of a bare TiO 2 powder. The experimental data reveal that at the light intensity stipulated by the operation procedure the amount of NO removed from the gas phase by photocatalytic oxidation is strongly affected by small changes of this light intensity as well as of the NO concentration in the gas stream in the photoreactor. Therefore, these parameters have to be controlled very carefully. Based upon the experimental data obtained in this study a rate law for the photocatalytic NO oxidation inside the photoreactor is derived.

Intensity limits for propagation of 0.527 μm laser beams through large-scale-length plasmas for inertial confinement fusion

International Nuclear Information System (INIS)

Niemann, C.; Divol, L.; Froula, D.H.; Gregori, G.; Jones, O.; Kirkwood, R.K.; MacKinnon, A.J.; Meezan, N.B.; Moody, J.D.; Sorce, C.; Suter, L.J.; Glenzer, S.H.; Bahr, R.; Seka, W.

2005-01-01

We have established the intensity limits for propagation of a frequency-doubled (2ω, 527 nm) high intensity interaction beam through an underdense large-scale-length plasma. We observe good beam transmission at laser intensities at or below 2x10 14 W/cm 2 and a strong reduction at intensities up to 10 15 W/cm 2 due to the onset of parametric scattering instabilities. We show that temporal beam smoothing by spectral dispersion allows a factor of 2 higher intensities while keeping the beam spray constant, which establishes frequency-doubled light as an option for ignition and burn in inertial confinement fusion experiments

Experiments on the interaction of intense femtosecond radiation with dense plasmas. Final report

International Nuclear Information System (INIS)

Rhodes, C.K.

1996-01-01

An upgraded KrF * (248 nm) system producing a pulse energy of ∼ 400 mJ, a pulse width of ∼ 220 fs, and focal intensities above 10 19 W/cm 2 , has been constructed, tested, operated, and used in experimental studies. The spatial morphology of channeled radiation in plasmas has been measured with a spatial resolution of ∼ 30 μm and damage studies of fused silica indicate that femtosecond (200 - 300 fs) 248 nm radiation has a damage limit not exceeding ∼ 50 GW/cm 2 , an unfavorably low level. 2 figs

Initial development of ponderomotive filaments in plasma from intense hot spots produced by a random phase plate

International Nuclear Information System (INIS)

Rose, H.A.; DuBois, D.F.

1993-01-01

Local intensity peaks, hot spots, in laser beams may initiate self-focusing, in lieu of linear instabilities. If the hot spot power, P, contains several times the critical power, P c , and if the plasma density, n, is small compared to the critical density, n c , then on a time scale less than an acoustic transit time across the hot spot radius, τ ia , the hot spot collapses, capturing order unity of the initial hot spot power. The collapse time is determined as a universal function of P/P c and τ ia . The focal region moves towards the laser with an initially supersonic speed, and decelerates as it propagates. The power of this back propagating focus decreases monotonically until the critical power is reached. This limiting, shallowest, focus develops on a time scale long compared to τ ia and corresponds to the focus obtained in a model with adiabatically responding ions. For low-density plasma nonlinear ion effects terminate collapse and a bound on the transient intensity amplification is obtained as a universal function of the optics f/number, F, and n/n c . The boundary between thermal and ponderomotive regimes depends upon F and not the laser intensity

Characterization of transient discharges under atmospheric-pressure conditions applying nitrogen photoemission and current measurements

International Nuclear Information System (INIS)

Keller, Sandra; Rajasekaran, Priyadarshini; Bibinov, Nikita; Awakowicz, Peter

2012-01-01

The plasma parameters such as electron distribution function and electron density of three atmospheric-pressure transient discharges namely filamentary and homogeneous dielectric barrier discharges in air, and the spark discharge of an argon plasma coagulation (APC) system are determined. A combination of numerical simulation as well as diagnostic methods including current measurement and optical emission spectroscopy (OES) based on nitrogen emissions is used. The applied methods supplement each other and resolve problems, which arise when these methods are used individually. Nitrogen is used as a sensor gas and is admixed in low amount to argon for characterizing the APC discharge. Both direct and stepwise electron-impact excitation of nitrogen emissions are included in the plasma-chemical model applied for characterization of these transient discharges using OES where ambiguity arises in the determination of plasma parameters under specific discharge conditions. It is shown that the measured current solves this problem by providing additional information useful for the determination of discharge-specific plasma parameters. (paper)

Theoretical investigation of dielectric corona pre-ionization TEA nitrogen laser based on transmission line method

Science.gov (United States)

Bahrampour, Alireza; Fallah, Robabeh; Ganjovi, Alireza A.; Bahrampour, Abolfazl

2007-07-01

This paper models the dielectric corona pre-ionization, capacitor transfer type of flat-plane transmission line traveling wave transverse excited atmospheric pressure nitrogen laser by a non-linear lumped RLC electric circuit. The flat-plane transmission line and the pre-ionizer dielectric are modeled by a lumped linear RLC and time-dependent non-linear RC circuit, respectively. The main discharge region is considered as a time-dependent non-linear RLC circuit where its resistance value is also depends on the radiated pre-ionization ultra violet (UV) intensity. The UV radiation is radiated by the resistance due to the surface plasma on the pre-ionizer dielectric. The theoretical predictions are in a very good agreement with the experimental observations. The electric circuit equations (including the ionization rate equations), the equations of laser levels population densities and propagation equation of laser intensities, are solved numerically. As a result, the effects of pre-ionizer dielectric parameters on the electrical behavior and output laser intensity are obtained.

Geometrical optimization of an ellipsoidal plasma mirror toward tight focusing of ultra-intense laser pulse

International Nuclear Information System (INIS)

Kon, A; Nakatsutsumi, M; Chen, Z L; Kodama, R; Buffechoux, S; Fuchs, J; Jin, Z

2010-01-01

We developed for the first time, very compact ( 3 ) extremely low f-number (f/number = 0.4) confocal ellipsoid focusing systems. Direct measurement of the laser focal spot using a low-energy laser beam indicates 1/5 reduction of the spot size compared to standard focusing (using a f/2.7 optics). Such mirror is thus able to achieve significant enhancement of the focused laser intensity without modifying the laser system itself. The mirror is then used under plasma mirror regime which enables us to compactify the size, to liberate us from the anxiety of protecting the optics from target debris after shots, and to enhance the temporal contrast. In this paper, we focus our attention to designing and optimizing the geometry of such innovative plasma optics.

Radiofrequency cold plasma nitrided carbon steel: Microstructural and micromechanical characterizations

International Nuclear Information System (INIS)

Bouanis, F.Z.; Bentiss, F.; Bellayer, S.; Vogt, J.B.; Jama, C.

2011-01-01

Highlights: → C38 carbon steel samples were plasma nitrided using a radiofrequency (rf) nitrogen plasma discharge. → RF plasma treatment enables nitriding for non-heated substrates. → The morphological and chemical analyses show the formation of a uniform thickness on the surface of the nitrided C38 steel. → Nitrogen plasma active species diffuse into the samples and lead to the formation of Fe x N. → The increase in microhardness values for nitrided samples with plasma processing time is interpreted by the formation of a thicker nitrided layer on the steel surface. - Abstract: In this work, C38 carbon steel was plasma nitrided using a radiofrequency (rf) nitrogen plasma discharge on non-heated substrates. General characterizations were performed to compare the chemical compositions, the microstructures and hardness of the untreated and plasma treated surfaces. The plasma nitriding was carried out on non-heated substrates at a pressure of 16.8 Pa, using N 2 gas. Surface characterizations before and after N 2 plasma treatment were performed by means of the electron probe microanalysis (EPMA), X-ray photoelectron spectroscopy (XPS) and Vickers microhardness measurements. The morphological and chemical analysis showed the formation of a uniform structure on the surface of the nitrided sample with enrichment in nitrogen when compared to untreated sample. The thickness of the nitride layer formed depends on the treatment time duration and is approximately 14 μm for 10 h of plasma treatment. XPS was employed to obtain chemical-state information of the plasma nitrided steel surfaces. The micromechanical results show that the surface microhardness increases as the plasma-processing time increases to reach, 1487 HV 0.005 at a plasma processing time of 8 h.

Radiofrequency cold plasma nitrided carbon steel: Microstructural and micromechanical characterizations

Energy Technology Data Exchange (ETDEWEB)

Bouanis, F.Z. [Universite Lille Nord de France, F-59000 Lille (France); Unite Materiaux et Transformations (UMET), Ingenierie des Systemes Polymeres, CNRS UMR 8207, ENSCL, BP 90108, F-59652 Villeneuve d' Ascq Cedex (France); Bentiss, F. [Laboratoire de Chimie de Coordination et d' Analytique, Faculte des Sciences, Universite Chouaib Doukkali, B.P. 20, M-24000 El Jadida (Morocco); Bellayer, S.; Vogt, J.B. [Universite Lille Nord de France, F-59000 Lille (France); Unite Materiaux et Transformations (UMET), Ingenierie des Systemes Polymeres, CNRS UMR 8207, ENSCL, BP 90108, F-59652 Villeneuve d' Ascq Cedex (France); Jama, C., E-mail: charafeddine.jama@ensc-lille.fr [Universite Lille Nord de France, F-59000 Lille (France); Unite Materiaux et Transformations (UMET), Ingenierie des Systemes Polymeres, CNRS UMR 8207, ENSCL, BP 90108, F-59652 Villeneuve d' Ascq Cedex (France)

2011-05-16

Highlights: {yields} C38 carbon steel samples were plasma nitrided using a radiofrequency (rf) nitrogen plasma discharge. {yields} RF plasma treatment enables nitriding for non-heated substrates. {yields} The morphological and chemical analyses show the formation of a uniform thickness on the surface of the nitrided C38 steel. {yields} Nitrogen plasma active species diffuse into the samples and lead to the formation of Fe{sub x}N. {yields} The increase in microhardness values for nitrided samples with plasma processing time is interpreted by the formation of a thicker nitrided layer on the steel surface. - Abstract: In this work, C38 carbon steel was plasma nitrided using a radiofrequency (rf) nitrogen plasma discharge on non-heated substrates. General characterizations were performed to compare the chemical compositions, the microstructures and hardness of the untreated and plasma treated surfaces. The plasma nitriding was carried out on non-heated substrates at a pressure of 16.8 Pa, using N{sub 2} gas. Surface characterizations before and after N{sub 2} plasma treatment were performed by means of the electron probe microanalysis (EPMA), X-ray photoelectron spectroscopy (XPS) and Vickers microhardness measurements. The morphological and chemical analysis showed the formation of a uniform structure on the surface of the nitrided sample with enrichment in nitrogen when compared to untreated sample. The thickness of the nitride layer formed depends on the treatment time duration and is approximately 14 {mu}m for 10 h of plasma treatment. XPS was employed to obtain chemical-state information of the plasma nitrided steel surfaces. The micromechanical results show that the surface microhardness increases as the plasma-processing time increases to reach, 1487 HV{sub 0.005} at a plasma processing time of 8 h.

Application to cleaning of waste plastic surfaces using atmospheric non-thermal plasma jets

Energy Technology Data Exchange (ETDEWEB)

Araya, Masayuki [Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502 (Japan); Yuji, Toshifumi [Graduate School of Science and Engineering, Tokyo Institute of Technology, 2-12-1 O-okayama, Meguro-ku, Tokyo 152-8550 (Japan)]. E-mail: t-yuji@hiroshima-cmt.ac.jp; Watanabe, Takayuki [Interdisciplinary Graduate School of Science and Engineering, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502 (Japan); Kashihara, Junzou [SHARP corporation, 1-9-2 Nakase, Mihama-Ku, Chiba 261-8520 (Japan); Sumida, Yoshitake [SHARP corporation, 2613-1 Ichinomoto-cho, Tenri 632-8567 (Japan)

2007-03-12

The removal of paint on the surface of waste plastics is difficult by the conventional process; in this research, a new cleaning mechanism using atmospheric plasmas was examined through optical emission spectroscopy, electron spectroscopy for chemical analysis, and scanning electron microscopy. Results indicate that an increase of pulse frequency enables for a short processing time for the removal of the paint film, signifying that the production of radicals in plasma, especially oxygen radicals, can be controlled by pulse frequency. Plasma jets were generated under the experimental conditions of an input power of 250 W to 400 W, a pulse frequency of 2 kHz to 12 kHz, and a plasma gas flow rate of 30 L/min. Examination of the intensity ratio of the reactive species, as measured by emission spectroscopy, showed that the O/N value increased with an increase in pulse frequency. Results of analysis with electron spectroscopy for chemical analysis show that nitrogen atoms and molybdenum in only the paint film decreased through plasma processing.

Application to cleaning of waste plastic surfaces using atmospheric non-thermal plasma jets

International Nuclear Information System (INIS)

Araya, Masayuki; Yuji, Toshifumi; Watanabe, Takayuki; Kashihara, Junzou; Sumida, Yoshitake

2007-01-01

The removal of paint on the surface of waste plastics is difficult by the conventional process; in this research, a new cleaning mechanism using atmospheric plasmas was examined through optical emission spectroscopy, electron spectroscopy for chemical analysis, and scanning electron microscopy. Results indicate that an increase of pulse frequency enables for a short processing time for the removal of the paint film, signifying that the production of radicals in plasma, especially oxygen radicals, can be controlled by pulse frequency. Plasma jets were generated under the experimental conditions of an input power of 250 W to 400 W, a pulse frequency of 2 kHz to 12 kHz, and a plasma gas flow rate of 30 L/min. Examination of the intensity ratio of the reactive species, as measured by emission spectroscopy, showed that the O/N value increased with an increase in pulse frequency. Results of analysis with electron spectroscopy for chemical analysis show that nitrogen atoms and molybdenum in only the paint film decreased through plasma processing

Gas injected washer plasma gun

International Nuclear Information System (INIS)

Jain, K.K.; John, P.I.; Punithavelu, A.M.; Rao, P.P.

1980-01-01

A plasma gun similar in geometry to the washer plasma gun has been operated with gas injected externally. hydrogen, nitrogen and argon plasmas have been ionised and accelerated to velocities of the order of 10 7 mm s -1 and densities 10 11 mm -3 . Higher parameter range is possible with higher electrical input power. (author)

Development of bipolar pulse accelerator for intense pulsed ion beam acceleration

International Nuclear Information System (INIS)

Fujioka, Y.; Mitsui, C.; Kitamura, I.; Takahashi, T.; Masugata, K.; Tanoue, H.; Arai, K.

2003-01-01

To improve the purity of an intense pulsed ion beams a new type of pulsed ion beam accelerator named 'bipolar pulse accelerator (BPA)' was proposed. In the accelerator purity of the beam is expected. To confirm the principle of the accelerator experimental system was developed. The system utilizes B y type magnetically insulated acceleration gap and operated with single polar negative pulse. A coaxial gas puff plasma gun placed in the grounded anode was used as an ion source, and source plasma (nitrogen) of current density approx. = 25 A/cm 2 , duration approx. = 1.5 μs was injected into the acceleration gap. The ions are successfully accelerated from the grounded anode to the drift tube by applying negative pulse of voltage 180 kV, duration 60 ns to the drift tube. Pulsed ion beam of current density approx. = 40 A/cm 2 , duration approx. 60 ns was obtained at 42 mm downstream from the anode surface. (author)

Generation of shock fronts in the interaction of short pulses of intense laser light in supercritical plasma

International Nuclear Information System (INIS)

Lopez V, V.E.; Ondarza R, R.

2004-01-01

The investigation of the laser interaction with plasma has been carried out mainly in laboratories of Europe, Japan and United States during the last decades. This studies concern the propagation of intense light laser in a non homogeneous plasma, the radiation absorption and the generation of suprathermal electrons, among others. Numerical simulations made by Denavit, for radiation pulses for up of 10 20 W/cm 2 on solid targets, have allowed to observe the generation of ionic crash fronts with high propagation speeds. In this work it is expanded the study of this effect through algorithms of particles simulation. (Author)

Errors and limits in the determination of plasma electron density by measuring the absolute values of the emitted continuum radiation intensity

International Nuclear Information System (INIS)

Bilbao, L.; Bruzzone, H.; Grondona, D.

1994-01-01

The reliable determination of a plasma electron structure requires a good knowledge of the errors affecting the employed technique. A technique based on the measurements of the absolute light intensity emitted by travelling plasma structures in plasma focus devices has been used, but it can be easily modified to other geometries and even to stationary plasma structures with time-varying plasma densities. The purpose of this work is to discuss in some detail the errors and limits of this technique. Three separate errors are shown: the minimum size of the density structure that can be resolved, an overall error in the measurements themselves, and an uncertainty in the shape of the density profile. (author)

Plasma source ion implantation

International Nuclear Information System (INIS)

Conrad, J.R.; Forest, C.

1986-01-01

The authors' technique allows the ion implantation to be performed directly within the ion source at higher currents without ion beam extraction and transport. The potential benefits include greatly increased production rates (factors of 10-1000) and the ability to implant non-planar targets without rastering or shadowing. The technique eliminates the ion extractor grid set, beam raster equipment, drift space and target manipulator equipment. The target to be implanted is placed directly within the plasma source and is biased to a large negative potential so that plasma ions gain energy as they accelerate through the potential drop across the sheath that forms at the plasma boundary. Because the sheath surrounds the target on all sides, all surfaces of the target are implanted without the necessity to raster the beam or to rotate the target. The authors have succeeded in implanting nitrogen ions in a silicon target to the depths and concentrations required for surface treatment of materials like stainless steel and titanium alloys. They have performed ESCA measurements of the penetration depth profile of a silicon target that was biased to 30 kV in a nitrogen discharge plasma. Nitrogen ions were implanted to a depth of 700A at a peak concentration of 30% atomic. The measured profile is quite similar to a previously obtained profile in titanium targets with conventional techniques

Plasma immersion ion implantation: duplex layers from a single process

International Nuclear Information System (INIS)

Hutchings, R.; Collins, G.A.; Tendys, J.

1992-01-01

Plasma immersion ion implantation (PI 3 ) is an alternative non-line-of-sight technique for implanting ions directly from a plasma which surrounds the component to be treated. In contrast to plasma source ion implantation, the PI 3 system uses an inductively coupled r.f. plasma. It is shown that nitrogen can be retained during implantation at elevated temperatures, even for unalloyed steels. This allows controlled diffusion of nitrogen to greater depths, thereby improving the load bearing capacity of the implanted layer. Components can be heated directly, using the energy deposited by the incident ions during the pulsed implantation. The necessary temperature control can be accomplished simply by regulating the frequency and length of the high voltage pulses applied to the component. Chemical depth profiles and microstructural data obtained from H13 tool steel are used to show that PI 3 can, in a single process, effectively produce a duplex subsurface structure. This structure consists of an outer non-equilibrium layer typical of nitrogen implantation (containing in excess of 20 at.% nitrogen) backed by a substantial diffusion zone of much lower nitrogen content. The relationship between implantation temperature and the resultant subsurface microstructure is explored. (orig.)

Plasma Channel Lenses and Plasma Tornadoes for Optical Beam Focusing and Transport

Science.gov (United States)

Hubbard, R. F.; Kaganovich, D.; Johnson, L. A.; Gordon, D. F.; Penano, J. R.; Hafizi, B.; Helle, M. H.; Mamonau, A. A.

2017-10-01

Shaped plasmas offer the possibility of manipulating laser pulses at intensities far above the damage limits for conventional optics. An example is the plasma channel, which is a cylindrical plasma column with an on-axis density minimum. Long plasma channels have been widely used to guide intense laser pulses, particularly in laser wakefield accelerators. A new concept, the ``plasma tornado'', offers the possibility of creating long plasma channels with no nearby structures and at densities lower than can be achieved by capillary discharges. A short plasma channel can focus a laser pulse in much the same manner as a conventional lens or off-axis parabola. When placed in front of the focal point of an intense laser pulse, a plasma channel lens (PCL) can reduce the effective f-number of conventional focusing optics. When placed beyond the focal point, it can act as a collimator. We will present experimental and modeling results for a new plasma tornado design, review experimental methods for generating short PCLs, and discuss potential applications. Supported by the Naval Research Laboratory Base Program.

Simulation of damage to tokamaks plasma facing components during intense abnormal power deposition

International Nuclear Information System (INIS)

Genco, F.; Hassanein, A.

2014-01-01

Highlights: • HEIGHTS-PIC a new technique based on particle in cell method to study disruptions events, ELMS and VDE is benchmarked in this paper with the use of the MK-200 experiments. • Disruptions simulations results for erosion and erosion rate are proposed showing good agreement with published experimental available data for such conditions. • Results are also compared with other published results produced by FOREV1/FOREV2 computer package and the original HEIGHTS computer package. • Accuracy of the simulations results is proposed with specific aim to address the use of number of super particles adopted versus computational time. - Abstract: Intense power deposition on plasma facing components (PFC) is expected in tokamaks during loss of confinement events such as disruptions, vertical displacement events (VDE), runaway electrons (RE), or during normal operating conditions such as edge-localized modes (ELM). These highly energetic events are damaging enough to hinder long term operation and may not be easily mitigated without loss of structural or functional performance of the PFC. Surface erosion, melted/ablated-vaporized material splashing, and material transport into the bulk plasma are reliability-threatening for the machine and system performance. A novel particle-in-cell (PIC) technique has been developed and integrated into the existing HEIGHTS package in order to obtain a global view of the plasma evolution upon energy impingement. This newly developed PIC technique is benchmarked against plasma gun experimental data, the original HEIGHTS computer package, and laser experiments. Benchmarking results are shown in this paper for various relevant reactor and experimental devices. The evolution of the plasma vapor cloud is followed temporally and results are explained and commented as a function of the computational time needed and the accuracy of the calculation

Influence of plasma parameters in pulsed plasma gun on modification processes in exposed structural materials

International Nuclear Information System (INIS)

Byrka, O.V.; Bandura, A.N.; Chebotarev, V.V.; Garkusha, I.E.; Garkusha, V.V.; Makhai, V.A.; Tereshin, V.I.

2011-01-01

This paper is focused on investigation of helium, nitrogen and krypton plasma streams generated by pulsed plasma gun (PPA). The main objection of this study is adjustment of plasma treatment regimes for different materials that allows achieving optimal thickness of modified layer with simultaneously minimal value of surface roughness. Features of materials alloying from gas and metallic plasma as a result of the plasma ions mixing with the steel substrate in liquid phase are discussed also.

Influence of temperature on properties of nitrogen plasma source ion implantation (N-PSII) of Ti6A14V alloy

CERN Document Server

Geng Man; Zhao Qing

2001-01-01

Specimens of Ti6Al4V alloy were implanted with nitrogen plasma source ion implantation (N-PSII) at temperatures between 100 degree C and 600 degree C to a ion dose of 4 x 10 sup 1 sup 7 cm sup - sup 2. Auger Electron Spectroscopy (AES) was used to determine the nitrogen concentration depth profiles. Microhardness measurements and pin-on-disk wear test were performed to evaluate the improvements of the surface modification. Glancing angle X-ray diffraction (XRD) was employed to determine the phases presented in the surface modified layer. The thickness of implanted layer increased by about an order of magnitude when the temperature was elevated from 100 degree C to 600 degree C. Higher surface hardness and wear resistance was also obtained at higher temperature. Scanning electron microscopy (SEM) showed distinct microstructural changes and the presence of titanium nitrides in the implanted surface

Analysis of the polymeric film and fine dust obtained in plasma of acetylene and acetylene-nitrogen

International Nuclear Information System (INIS)

Rojas, Andres F; Ortiz, Jairo A; Devia Alfonso

1998-01-01

The results are presented from the resistance analyses to the corrosion of the polymeric covering obtained in plasma of acetylene, on a substrata of aluminum alloy, with the techniques of metallographic analysis, infrared and electrochemical, as much for the fine dust as for the grown film on aluminum. Also, the results of the electrochemical test of polarization made to these films will be shown, which demonstrated an improvement of 2.6 and 4.6 times in the resistance to the corrosion when the material treaty is exposed NaCl 0.2 N and Na H2 PO4 01 M, respectively, in comparison with the substrata without recovering. For the movie obtained in acetylene /nitrogen plasma on steel 1016 the micrographs of the superficial structure of the material they will be shown before and after being treated, which were used to measure the thickness of the cover; also, it will be given to know the results of the tests of adhesion and qualitative analysis of resistance before diverse chemical agents (such as: Benzene, Toluene, H2SO4, HNO3, NaCl, CACO3 NaOH and KOH) and the resistance results are presented from the cover to them

Spatial variation in atmospheric nitrogen deposition on low canopy vegetation

International Nuclear Information System (INIS)

Verhagen, Rene; Diggelen, Rudy van

2006-01-01

Current knowledge about the spatial variation of atmospheric nitrogen deposition on a local scale is limited, especially for vegetation with a low canopy. We measured nitrogen deposition on artificial vegetation at variable distances of local nitrogen emitting sources in three nature reserves in the Netherlands, differing in the intensity of agricultural practices in the surroundings. In the nature reserve located in the most intensive agricultural region nitrogen deposition decreased with increasing distance to the local farms, until at a distance of 1500 m from the local nitrogen emitting sources the background level of 15 kg N ha -1 yr -1 was reached. No such trend was observed in the other two reserves. Interception was considerably lower than in woodlands and hence affected areas were larger. The results are discussed in relation to the prospects for the conservation or restoration of endangered vegetation types of nutrient-poor soil conditions. - Areas with low canopy vegetation are affected over much larger distances by nitrogen deposition than woodlands

E-H mode transition in low-pressure inductively coupled nitrogen-argon and oxygen-argon plasmas

International Nuclear Information System (INIS)

Lee, Young Wook; Lee, Hye Lan; Chung, T. H.

2011-01-01

This work investigates the characteristics of the E-H mode transition in low-pressure inductively coupled N 2 -Ar and O 2 -Ar discharges using rf-compensated Langmuir probe measurements and optical emission spectroscopy (OES). As the ICP power increases, the emission intensities from plasma species, the electron density, the electron temperature, and the plasma potential exhibit sudden changes. The Ar content in the gas mixture and total gas pressure have been varied in an attempt to fully characterize the plasma parameters. With these control parameters varying, the changes of the transition threshold power and the electron energy distribution function (EEDF) are explored. In N 2 -Ar and O 2 -Ar discharges at low-pressures of several millitorr, the transition thresholds are observed to decrease with Ar content and pressure. It is observed that in N 2 -Ar plasmas during the transition, the shape of the EEDF changes from an unusual distribution with a flat hole near the electron energy of 3 eV in the E mode to a Maxwellian distribution in the H mode. However, in O 2 -Ar plasmas, the EEDFs in the E mode at low Ar contents show roughly bi-Maxwellian distributions, while the EEDFs in the H mode are observed to be nearly Maxwellian. In the E and H modes of O 2 -Ar discharges, the dissociation fraction of O 2 molecules is estimated using optical emission actinometry. During the E-H mode transition, the dissociation fraction of molecules is also enhanced.

Plasma polarization spectroscopy

International Nuclear Information System (INIS)

Iwamae, Atsushi; Horimoto, Yasuhiro; Fujimoto, Takashi; Hasegawa, Noboru; Sukegawa, Kouta; Kawachi, Tetsuya

2005-01-01

The electron velocity distribution function (EVDF) in plasma can be anisotropic in laser-produced plasmas. We have developed a new technique to evaluate the polarization degree of the emission lines in the extreme vacuum ultra violet wavelength region. The polarization of the emission lines and the continuums from the lithium-like nitrogen and from helium- and hydrogen-like carbon in recombining plasma is evaluated. Particle simulation in the velocity space gives the time scale for relaxation of anisotropic EVDFs. (author)

Surface modification of biphasic calcium phosphate scaffolds by non-thermal atmospheric pressure nitrogen and air plasma treatment for improving osteoblast attachment and proliferation

International Nuclear Information System (INIS)

Choi, Yu-Ri; Kwon, Jae-Sung; Song, Doo-Hoon; Choi, Eun Ha; Lee, Yong-Keun; Kim, Kyoung-Nam; Kim, Kwang-Mahn

2013-01-01

Surface modifications induced by non-thermal plasma have been used extensively in biomedical applications. The attachment and proliferation of osteoblast cells are important in bone tissue engineering using scaffolds. Hence the effect of non-thermal plasma on hydroxyapatite/β-tri-calcium phosphate (HA/β-TCP) scaffolds in terms of improving osteoblast attachment and proliferation was investigated. Experimental groups were treated with non-thermal plasma for 10 min and 20 min and a control group was not treated with non-thermal plasma. For surface chemistry analysis, X-ray photoelectron spectroscopy (XPS) analysis was carried out. The hydrophilicity was determined from contact angle measurement on the surface. Atomic force microscopy analysis (AFM) was used to test the change in surface roughness and cell attachment and proliferation were evaluated using MC3T3-E1 osteoblast cells. XPS spectra revealed a decreased amount of carbon on the surface of the plasma-treated sample. The contact angle was also decreased following plasma treatment, indicating improved hydrophilicity of plasma-treated surfaces compared to the untreated disc. A significant increase in MC3T3E-1 cell attachment and proliferation was noted on plasma-treated samples as compared to untreated specimens. The results suggest that non-thermal atmospheric pressure nitrogen and air plasma treatments provide beneficial surface characteristics on HA/β-TCP scaffolds. - Highlights: ► Non-thermal plasma increased OH- and decreased C on biphasic scaffold. ► Non-thermal plasma had no effect on surface roughness. ► Non-thermal plasma resulted in hydrophilic surface. ► Non-thermal plasma resulted in better cell attachment and proliferation. ► Non-thermal plasma treatment on biphasic scaffold is useful for tissue engineering

On-line depth measurement for laser-drilled holes based on the intensity of plasma emission

Science.gov (United States)

Ho, Chao-Ching; Chiu, Chih-Mu; Chang, Yuan-Jen; Hsu, Jin-Chen; Kuo, Chia-Lung

2014-09-01

The direct time-resolved depth measurement of blind holes is extremely difficult due to the short time interval and the limited space inside the hole. This work presents a method that involves on-line plasma emission acquisition and analysis to obtain correlations between the machining processes and the optical signal output. Given that the depths of laser-machined holes can be estimated on-line using a coaxial photodiode, this was employed in our inspection system. Our experiments were conducted in air under normal atmospheric conditions without gas assist. The intensity of radiation emitted from the vaporized material was found to correlate with the depth of the hole. The results indicate that the estimated depths of the laser-drilled holes were inversely proportional to the maximum plasma light emission measured for a given laser pulse number.

Dynamic behaviour of dc double anode plasma torch at atmospheric pressure

International Nuclear Information System (INIS)

Tu, X; Cheron, B G; Yan, J H; Cen, K F

2007-01-01

An original dc double anode plasma torch which provides a long-time and highly stable atmospheric plasma jet has been devised for the purpose of hazardous waste treatment. The arc fluctuations and dynamic behaviour of the argon and argon-nitrogen plasma jets under different operating conditions have been investigated by means of classical tools, such as the statistic method, fast Fourier transform (FFT) and correlation analysis. In our experiments, the takeover mode is identified as the fluctuation characteristic of the argon plasma jet while the restrike mode is typical in the argon-nitrogen plasma dynamic behaviour. In the case of pure argon, the FFT and correlation calculation results of electrical signals exhibit the only characteristic frequency of 150 Hz, which originates from the torch power and is independent of any change in the operating conditions. It indicates that the nature of fluctuations in an argon plasma jet is mainly induced by the undulation of the tri-phase rectified power supply. In contrast, besides the same low frequency bulk fluctuation, the dynamic behaviour of the argon-nitrogen plasma jet at high frequency (4.1 kHz) is ascribed to the rapid motion of both arc roots on the anode surface. In addition, it is found that each arc root attachment is rather diffused than located at a fixed position on the anode wall in the argon plasma jet, while constricted arc roots occur when nitrogen is added into argon as the plasma working gas

Ultraviolet electroluminescence from nitrogen-doped ZnO-based heterojuntion light-emitting diodes prepared by remote plasma in situ atomic layer-doping technique.

Science.gov (United States)

Chien, Jui-Fen; Liao, Hua-Yang; Yu, Sheng-Fu; Lin, Ray-Ming; Shiojiri, Makoto; Shyue, Jing-Jong; Chen, Miin-Jang

2013-01-23

Remote plasma in situ atomic layer doping technique was applied to prepare an n-type nitrogen-doped ZnO (n-ZnO:N) layer upon p-type magnesium-doped GaN (p-GaN:Mg) to fabricate the n-ZnO:N/p-GaN:Mg heterojuntion light-emitting diodes. The room-temperature electroluminescence exhibits a dominant ultraviolet peak at λ ≈ 370 nm from ZnO band-edge emission and suppressed luminescence from GaN, as a result of the decrease in electron concentration in ZnO and reduced electron injection from n-ZnO:N to p-GaN:Mg because of the nitrogen incorporation. The result indicates that the in situ atomic layer doping technique is an effective approach to tailoring the electrical properties of materials in device applications.

Investigation on the Assimilation of Nitrogen by Maize Roots and the Transport of Some Major Nitrogen Compounds by Xylem Sap

DEFF Research Database (Denmark)

Ivanko, S.; Ingversen, J.

1971-01-01

The uptake and assimilation of nitrate and ammonia have been studied in Zea mays. Nitrogen-starved maize roots are capable of accumulating a potential capacity for nitrogen uptake and assimilation. Reestablishment of nitrogen supply leads to intense uptake, reaching 154 % of the reference variant...... level after 24 hours when nitrate is supplied, and 121 % when ammonia is supplied. After 24 hours the insoluble nitrogen fraction accounts for 80, 54 and 55 % of the total taken up in the PK + NO3-, PK + NH4+ and NPK variants respectively....

CN molecule vibrational spectra excitation in several LTE plasma sources conditions

International Nuclear Information System (INIS)

Iova, I.; Iova, Floriana; Ionita, I.; Bazavan, M.; Ilie, Gh.; Stanescu, G.

2001-01-01

Our interest in CN plasma study steams of the facilities to obtain the CN radicals in a free atmosphere electric discharge where the C of the coal electrodes can to combine in the enough high temperature plasma with the atmospheric nitrogen. Also of much interest is the very important phenomena in which the CN vibrational spectra can be implied and used as a diagnostic tool (plasma chemistry, astrophysics and so on). A peculiar importance presents the CN vibrational spectra in the transient plasmas. It is the reason why we have investigated here some internal processes of a continued and interrupted arc of various pulse lengths. To these purposes we present with enough accuracy the behaviour of the relative band head intensities of the sequences Δ v = +1 and Δ v = 0 belonging to the CN electronic transition (B 2 Σ - X 2 Σ), as a function of the pulse length (50 - 200 ms) as well as a function of the cathode to anode separation. These behaviours give us indications on the vibrational levels of the electronic state populations in several regions of the arc plasma as well on the efficiency of these levels excitation for several plasma pulse lengths. (authors)

Metal surface nitriding by laser induced plasma

Science.gov (United States)

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

1996-10-01

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

Proton emission from laser-generated plasmas at different intensities

Czech Academy of Sciences Publication Activity Database

Torrisi, L.; Cutroneo, M.; Cavallaro, S.; Giuffrida, L.; Margarone, Daniele

2012-01-01

Roč. 57, č. 2 (2012), s. 237-240 ISSN 0029-5922. [International Conference on Research and Applications of Plasmas (PLASMA). Warsaw, 12.09.2011-16.09.2011] Institutional support: RVO:68378271 Keywords : laser-generated plasma * hydrogenated targets * proton acceleration Subject RIV: BL - Plasma and Gas Discharge Physics Impact factor: 0.507, year: 2012

Spectroscopic study of emission coal mineral plasma produced by laser ablation

International Nuclear Information System (INIS)

Vera, L P; Pérez, J A; Riascos, H

2014-01-01

Spectroscopic analysis of plasma produced by laser ablation of coal samples using 1064 nm radiation pulses from a Q-switched Nd:YAG on different target under air ambient, was performed. The emission of molecular band systems such as C 2 Swan System (d 3 Π g →a 3 Π u ), the First Negative System N 2 (Band head at 501,53 nm) and emission lines of the C I, C II, were investigated using the optical emission spectroscopy technique. The C 2 molecular spectra (Swan band) were analyzed to determine vibrational temperature (0,62 eV); the density and electron temperature of the plasma have been evaluated using Stark broadening and the intensity of the nitrogen emission lines N II, the found values of 1,2 eV and 2,2 x10 18 cm −3 respectively.

Extremely high-power-density atmospheric-pressure thermal plasma jet generated by the nitrogen-boosted effect

Science.gov (United States)

Hanafusa, Hiroaki; Nakashima, Ryosuke; Nakano, Wataru; Higashi, Seiichiro

2018-06-01

In this study, the effect of N2 addition to an atmospheric-pressure Ar thermal plasma jet (TPJ) on ultrarapid heating was investigated. With increasing N2 flow rate, a boost of arc voltage to ∼36 V was observed, which significantly improved heating characteristics. As a result, a drastic power density increase from 10 to 125 kW/cm2 was achieved with the addition of 2.0 L/min N2 to 3.0 L/min Ar. The results of optical emission analysis and heating characteristics evaluation implied that dissociation and recombination of N2 molecules and the high thermal transport property of nitrogen gas play important roles in the increase in TPJ power density. Furthermore, we obtained TPJ extension with N2 addition that reached 300 mm, and it showed spatial enhancement of heat transport characteristics.

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.)

Sterilization and decontamination of medical instruments by low-pressure plasma discharges: application of Ar/O{sub 2}/N{sub 2} ternary mixture

Energy Technology Data Exchange (ETDEWEB)

Kylian, O [Charles University, Faculty of Mathematics and Physics, V Holesovickach 2, Prague 8, 180 00 (Czech Republic); Rossi, F, E-mail: francois.rossi@jrc.i [European Commission, Joint Research Centre, Institute for Health and Consumer Protection, Via E Fermi 2749, 21027 Ispra (Vatican City State, Holy See) (Italy)

2009-04-21

A low-pressure inductively coupled plasma discharge sustained in an argon-oxygen-nitrogen ternary mixture is studied in order to evaluate its properties in terms of sterilization and decontamination of surfaces of medical instruments. It is demonstrated by direct comparison with discharges operated in oxygen-nitrogen and oxygen-argon mixtures that application of an Ar/O{sub 2}/N{sub 2} mixture offers the possibility to combine advantageous properties of the binary mixtures, namely, the capability of an O{sub 2}/N{sub 2} plasma to emit intense UV radiation needed for effective inactivation of bacterial spores together with high removal rates of biological substances from Ar/O{sub 2} discharge. Moreover, optimal conditions for both effects are obtained at a similar ternary discharge mixture composition, which is of much interest for real applications, since it offers a highly effective process desired for the safety of medical instruments.

An application of nitrogen microwave-induced plasma mass spectrometry to isotope dilution analysis of selenium in marine organisms

Energy Technology Data Exchange (ETDEWEB)

Shirasaki, Toshihiro [Hitachi Instruments Engineering Co. Ltd., Hitachinaka, Ibaraki (Japan); Yoshinaga, Jun; Morita, Masatoshi; Okumoto, Toyoharu; Oishi, Konosuke

1996-01-01

Nitrogen microwave-induced plasma mass spectrometry was studied for its applicability to the isotope dilution analysis of selenium in biological samples. Spectroscopic interference by calcium, which is present in high concentrations in biological samples, was investigated. No detectable background spectrum was observed for the major selenium isotopes of {sup 78}Se and {sup 80}Se. No detectable interferences by sodium, potassium, calcium and phosphorus on the isotope ratio {sup 80}Se/{sup 78}Se were observed up to concentration of 200 mg/ml. The method was applied to the analysis of selenium in biological reference materials of marine organisms. The results showed good agreement between the certified and found values. (author).

The origin of traps and the effect of nitrogen plasma in oxide-nitride-oxide structures for non-volatile memories

International Nuclear Information System (INIS)

Kim, W. S.; Kwak, D. W.; Oh, J. S.; Lee, D. W.; Cho, H. Y.

2010-01-01

Ultrathin oxide-nitride-oxide (ONO) dielectric stacked layers are fundamental structures of silicon-oxide-nitride-oxide-silicon (SONOS) non-volatile memory devices in which information is known to be stored as charges trapped in silicon nitride. Deep-level transient spectroscopy (DLTS) and a capacitance-voltage (CV) analysis were introduced to observe the trap behavior related to the memory effect in memory devices. The DLTS results verified that the nitride-related traps were a dominant factor in the memory effect. The energy of hole traps was 0.307 eV above the balance band. To improve the memory effects of the non-volatile memory devices with ONO structures, we introduced a nitrogen plasma treatment. After the N-plasma treatment, the flat-band voltage shift (ΔV FB ) was increased by about 1.5 times. The program and the erase (P-E) characteristics were also shown to be better than those for the as-ONO structure. In addition, the retention characteristics were improved by over 2.4 times.

Commercial and home-made nitrogen modified titanias. A short reflection about the advantageous/disadvantageous properties of nitrogen doping in the frame of their applicability

Science.gov (United States)

Pap, Zs.; Mogyorósi, K.; Veréb, G.; Dombi, A.; Hernádi, K.; Danciu, V.; Baia, L.

2014-09-01

As visible light driven photocatalysis became more and more intensively studied, the first commercial products showed up on the market. Simultaneously controversial results appeared in the literature generating an intensive debate regarding the advantages and draw-backs of nitrogen doping of titania. Hence, the present work focuses on two commercially available and four sol-gel made nitrogen modified titania powders regarding their structure and activity. It is demonstrated that the interstitial nitrogen entities “leak out” from the catalysts if the material is irradiated with UV light, while substitutional nitrogen remains stable. However, the latter one was proven to be less important in the photocatalytic point of view. These observations were also valid in the case of sol-gel made nitrogen modified titanias. Furthermore, the results obtained after applying different spectroscopic methods (IR, XPS and DRS) shown that the yellow color of the titanias, does not necessary mean that a successful doping is achieved.

Pulsed-Plasma Disinfection of Water Containing Escherichia coli

Science.gov (United States)

Satoh, Kohki; MacGregor, Scott J.; Anderson, John G.; Woolsey, Gerry A.; Fouracre, R. Anthony

2007-03-01

The disinfection of water containing the microorganism, Escherichia coli (E. coli) by exposure to a pulsed-discharge plasma generated above the water using a multineedle electrode (plasma-exposure treatment), and by sparging the off-gas of the pulsed plasma into the water (off-gas-sparging treatment), is performed in the ambient gases of air, oxygen, and nitrogen. For the off-gas-sparging treatment, bactericidal action is observed only when oxygen is used as the ambient gas, and ozone is found to generate the bactericidal action. For the plasma-exposure treatment, the density of E. coli bacteria decreases exponentially with plasma-exposure time for all the ambient gases. It may be concluded that the main contributors to E. coli inactivation are particle species produced by the pulsed plasma. For the ambient gases of air and nitrogen, the influence of acidification of the water in the system, as a result of pulsed-plasma exposure, may also contribute to the decay of E. coli density.

Behavior of an indigenously fabricated transferred arc plasma furnace for smelting studies

Science.gov (United States)

A, K. MANDAL; R, K. DISHWAR; O, P. SINHA

2018-03-01

The utilization of industrial solid waste for metal recovery requires high-temperature tools due to the presence of silica and alumina, which is reducible at high temperature. In a plasma arc furnace, transferred arc plasma furnace (TAP) can meet all requirements, but the disadvantage of this technology is the high cost. For performing experiments in the laboratory, the TAP was fabricated indigenously in a laboratory based on the different inputs provided in the literature for the furnace design and fabrication. The observed parameters such as arc length, energy consumption, graphite electrode consumption, noise level as well as lining erosion were characterized for this fabricated furnace. The nitrogen plasma increased by around 200 K (200 °C) melt temperature and noise levels decreased by ∼10 dB compared to a normal arc. Hydrogen plasma offered 100 K (100 °C) higher melt temperature with ∼5 dB higher sound level than nitrogen plasma. Nitrogen plasma arc melting showed lower electrode and energy consumption than normal arc melting, whereas hydrogen plasma showed lower energy consumption and higher electrode consumption in comparison to nitrogen plasma. The higher plasma arc temperature resulted in a shorter meltdown time than normal arc with smoother arcing. Hydrogen plasma permitted more heats, reduced meltdown time, and lower energy consumption, but with increased graphite consumption and crucible wear. The present study showed that the fabricated arc plasma is better than the normal arc furnace with respect to temperature generation, energy consumption, and environmental friendliness. Therefore, it could be used effectively for smelting-reduction studies.

Isotope exchange investigation of nitrogen redistribution in expanded austenite

DEFF Research Database (Denmark)

Christiansen, Thomas Lundin; Drouet, M.; Martinavičius, A.

2013-01-01

Sequential plasma and gaseous nitriding of Fe–18Cr–10Ni–3Mo stainless steel at 390°C with 14N and 15N isotopes followed by denitriding in flowing hydrogen was investigated. Redistribution of plasma-inserted nitrogen atoms (15N) by subsequent gaseous nitriding (14N) was observed. Denitriding after...

Wet nitrogen deposition across the urban-intensive agricultural-rural transect of a small urban area in southwest China.

Science.gov (United States)

Deng, Ouping; Zhang, Shirong; Deng, Liangji; Zhang, Chunlong; Fei, Jianbo

2018-03-01

Understanding of the spatial and temporal variation of the flux of atmospheric nitrogen (N) deposition is essential for assessment of its impact on ecosystems. However, little attention has been paid to the variability of N deposition across urban-intensive agricultural-rural transects. A continuous 2-year observational study (from January 2015 to December 2016) was conducted to determine wet N deposition across the urban-intensive agricultural-rural transect of a small urban area in southwest China. Significantly spatial and temporal variations were found in the research area. Along the urban-intensive agricultural-rural transect, the TN and NH 4 + -N deposition first increased and then decreased, and the NO 3 - -N and dissolved organic N (DON) deposition decreased continuously. Wet N deposition was mainly affected by the districts of agro-facilities, roads and build up lands. Wet NH 4 + -N deposition had non-seasonal emission sources including industrial emissions and urban excretory wastes in urban districts and seasonal emission sources such as fertilizer and manure volatilization in the other districts. However, wet NO 3 - -N deposition had seasonal emission sources such as industrial emissions and fireworks in urban district and non-seasonal emission sources such as transportation in the other districts. Deposition of DON was likely to have had similar sources to NO 3 - -N deposition in rural district, and high-temperature-dependent sources in urban and intensive agricultural districts. Considering the annual wet TN deposition in the intensive agricultural district was about 11.1% of the annual N fertilizer input, N fertilizer rates of crops should be reduced in this region to avoid the excessive application, and the risk of N emissions to the environment.

Some estimates of mirror plasma startup by neutral beam heating of pellet and gas cloud targets

International Nuclear Information System (INIS)

Shearer, J.W.; Willmann, P.A.

1978-01-01

Hot plasma buildup by neutral beam injection into an initially cold solid or gaseous target is found to be conceivable in large mirror machine experiments such as 2XIIB or MFTF. A simple analysis shows that existing neutral beam intensities are sufficient to ablate suitable targets to form a gas or vapor cloud. An approximate rate equation model is used to follow the subsequent processes of ionization, heating, and hot plasma formation. Solutions of these rate equations are obtained by means of the ''GEAR'' techniques for solving ''stiff'' systems of differential equations. These solutions are in rough agreement with the 2XIIB stream plasma buildup experiment. They also predict that buildup on a suitable nitrogen-like target will occur in the MFTF geometry. In 2XIIB the solutions are marginal; buildup may be possible, but is not certain

Research on atmospheric pressure plasma processing sewage

Science.gov (United States)

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

2013-08-01

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

Designing Neutralized Drift Compression for Focusing of Intense Ion Beam Pulses in a Background Plasma

International Nuclear Information System (INIS)

Kaganovich, I.D.; Davidson, R.C.; Dorf, M.; Startsev, E.A.; Barnard, J.J.; Friedman, A.; Lee, E.P.; Lidia, S.M.; Logan, B.G.; Roy, P.K.; Seidl, P.A.; Welch, D.R.; Sefkow, A.B.

2009-01-01

Neutralized drift compression offers an effective method for particle beam focusing and current amplification. In neutralized drift compression, a linear radial and longitudinal velocity drift is applied to a beam pulse, so that the beam pulse compresses as it drifts in the drift-compression section. The beam intensity can increase more than a factor of 100 in both the radial and longitudinal directions, resulting in more than 10,000 times increase in the beam number density during this process. The self-electric and self-magnetic fields can prevent tight ballistic focusing and have to be neutralized by supplying neutralizing electrons. This paper presents a survey of the present theoretical understanding of the drift compression process and plasma neutralization of intense particle beams. The optimal configuration of focusing and neutralizing elements is discussed in this paper.

Toward a Mechanistic Modeling of Nitrogen Limitation on Vegetation Dynamics

OpenAIRE

Xu, Chonggang; Fisher, Rosie; Wullschleger, Stan D.; Wilson, Cathy J.; Cai, Michael; McDowell, Nate G.

2012-01-01

Nitrogen is a dominant regulator of vegetation dynamics, net primary production, and terrestrial carbon cycles; however, most ecosystem models use a rather simplistic relationship between leaf nitrogen content and photosynthetic capacity. Such an approach does not consider how patterns of nitrogen allocation may change with differences in light intensity, growing-season temperature and CO(2) concentration. To account for this known variability in nitrogen-photosynthesis relationships, we deve...

The relation between the production efficiency of nitrogen atoms and the electrical characteristics of a dielectric barrier discharge

NARCIS (Netherlands)

Peeters, F.J.J.; Yang, R.; van de Sanden, M.C.M.

2015-01-01

In a nitrogen plasma jet, atomic nitrogen is the longest lived radical species and, through recombination, gives rise to highly reactive excited nitrogen species. In this paper, the atomic nitrogen concentration in the effluent of a nitrogen-fed dielectric barrier discharge (DBD) is determined by

Plasma satellites of X-ray lines of ions in a picosecond laser plasma

International Nuclear Information System (INIS)

Belyaev, V.S.; Vinogradov, V.I.; Kurilov, A.S.; Matafonov, A.P.; Lisitsa, V.S.; Gavrilenko, V. P.; Faenov, A.Ya.; Pikuz, T.A.; Skobelev, I.Yu.; Magunov, A.I.; Pikuz, S.A. Jr.

2004-01-01

We present the results of our measurements of the spectra for multicharged ions in a plasma produced by moderately intense (about 10 17 W cm -2 ) picosecond laser pulses. They suggest the existence of intense plasma oscillations with a frequency appreciably lower than the frequency of the laser radiation. The observed spectrum for the plasma satellites of the Lyman Ly α doublet of the hydrogenic F IX ion in a dense plasma was modeled theoretically. The resulting doublet profile was shown to have a complex structure that depends nontrivially both on the plasma density and on the frequency and amplitude of the plasma oscillations. The positions of the satellites and their separations allowed them to be associated with intense electrostatic oscillations with an amplitude of (4-6) x 10 8 V cm -1 and a frequency near (0.7-1) x 10 15 s -1 . Assuming the oscillation frequency to be determined by the strength of the magnetic field B generated in the plasma, we obtained an estimate of B that is in reasonable agreement with other measurements and estimates of this quantity. Our theoretical analysis allowed explanation of the emission spectra observed when flat fluoroplastic targets were heated by intense picosecond laser pulses

Simulation of N-atom production in dielectric-barrier discharge in nitrogen at atmospheric pressure

International Nuclear Information System (INIS)

Tsyganov, Dmitry; Pancheshnyi, Sergey

2012-01-01

A plasma-chemical model of atomic nitrogen production in a Townsend dielectric-barrier discharge in nitrogen at atmospheric pressure is presented. On the basis of the comparison with measured densities, a significant discrepancy between the calculated and the measured production rate of nitrogen atoms is observed and discussed. (paper)