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1

Breakdown voltages for discharges initiated from plasma pulses produced by high-frequency excimer lasers  

SciTech Connect

The triggering ability under the different electric field was investigated using a KrF excimer laser with a high repetition rate of kilohertz order. Measurements were made of the magnitude of impulse voltages that were required to initiate a discharge from plasmas produced by a high-frequency excimer laser. Breakdown voltages were found to be reduced by 50% through the production of plasmas in the discharge gap by a high-frequency excimer laser. However, under direct-current electric field, triggering ability decreased drastically due to low plasma density. It is considered that such laser operation applied for laser-triggered lightning due to the produced location of plasma channel is formed under the impulse electric field since an electric field of the location drastically reduces temporary when the downward leader from thunderclouds propagates to the plasma channel.

Yamaura, Michiteru [Department of Electrical and Electronic Engineering, Faculty of Science and Engineering, Saga University, 1 Honjo-machi, Saga 840-8502 (Japan)

2006-06-19

2

Breakdown voltages for discharges initiated from plasma pulses produced by high-frequency excimer lasers  

NASA Astrophysics Data System (ADS)

The triggering ability under the different electric field was investigated using a KrF excimer laser with a high repetition rate of kilohertz order. Measurements were made of the magnitude of impulse voltages that were required to initiate a discharge from plasmas produced by a high-frequency excimer laser. Breakdown voltages were found to be reduced by 50% through the production of plasmas in the discharge gap by a high-frequency excimer laser. However, under direct-current electric field, triggering ability decreased drastically due to low plasma density. It is considered that such laser operation applied for laser-triggered lightning due to the produced location of plasma channel is formed under the impulse electric field since an electric field of the location drastically reduces temporary when the downward leader from thunderclouds propagates to the plasma channel.

Yamaura, Michiteru

2006-06-01

3

Fusion reactions initiated by laser-accelerated particle beams in a laser-produced plasma  

E-print Network

The advent of high-intensity pulsed laser technology enables the generation of extreme states of matter under conditions that are far from thermal equilibrium. This in turn could enable different approaches to generating energy from nuclear fusion. Relaxing the equilibrium requirement could widen the range of isotopes used in fusion fuels permitting cleaner and less hazardous reactions that do not produce high energy neutrons. Here we propose and implement a means to drive fusion reactions between protons and boron-11 nuclei, by colliding a laser-accelerated proton beam with a laser-generated boron plasma. We report proton-boron reaction rates that are orders of magnitude higher than those reported previously. Beyond fusion, our approach demonstrates a new means for exploring low-energy nuclear reactions such as those that occur in astrophysical plasmas and related environments.

Labaune, C; Depierreux, S; Goyon, C; Loisel, G; Yahia, V; Rafelski, J

2013-01-01

4

Fusion reactions initiated by laser-accelerated particle beams in a laser-produced plasma.  

PubMed

The advent of high-intensity-pulsed laser technology enables the generation of extreme states of matter under conditions that are far from thermal equilibrium. This in turn could enable different approaches to generating energy from nuclear fusion. Relaxing the equilibrium requirement could widen the range of isotopes used in fusion fuels permitting cleaner and less hazardous reactions that do not produce high-energy neutrons. Here we propose and implement a means to drive fusion reactions between protons and boron-11 nuclei by colliding a laser-accelerated proton beam with a laser-generated boron plasma. We report proton-boron reaction rates that are orders of magnitude higher than those reported previously. Beyond fusion, our approach demonstrates a new means for exploring low-energy nuclear reactions such as those that occur in astrophysical plasmas and related environments. PMID:24104859

Labaune, C; Baccou, C; Depierreux, S; Goyon, C; Loisel, G; Yahia, V; Rafelski, J

2013-01-01

5

Initial measurements in the Fisk Plasma Source  

NASA Astrophysics Data System (ADS)

A new plasma source, the Fisk Plasma Source (FPS), has been developed at Fisk University. This plasma device will be used to study the physics of low temperature plasmas and plasma-materials interactions. The FPS device is a stainless steel 6-way cross vacuum vessel with a 10 inch inner diameter. Low temperature argon plasmas are generated using a DC glow discharge technique. Two selenoid electromagnets are wound directly on to the exterior of the vacuum vessel to produce magnetic fields of up to 200 Gauss. Langmuir probe measurements are used to determine spatial profiles of the plasma density and the electron temperature. We present experimental measurements of density and temperature profiles in the FPS device. We will also present the results of initial plasma-material interaction studies.

Wallace, Kent; Lampkin, Gregory; Thomas, Edward; Chen, Henry

1997-11-01

6

Laser-produced plasmas in medicine  

Microsoft Academic Search

The authors have examined the characteristics of plasmas that are produced in laser medicine. In particular, they considered plasmas produced in laser lithotripsy (stone ablation and fragmentation by dye laser) and in ocular photodisruption (lens membrane destruction by Nd:YAG lasers following cataract surgery). Their interest was in what aspects of these plasmas make them useful to these applications. Experimental data

S. J. Gitomer; R. D. Jones; C. Howsare

1989-01-01

7

Laser-produced plasmas in medicine  

Microsoft Academic Search

The authors examine those areas of laser medicine in which plasmas (ionized gases) are produced. In fact, the presence of a plasma is essential for the various applications to succeed. The authors consider examples of the plasmas produced in ophthalmology (e.g., lens membrane destruction following cataract surgery), in urology and gastroenterology (e.g., kidney and gall stone ablation and fragmentation), and

Steven J. Gitomer; Roger D. Jones

1991-01-01

8

Gas lens laser produced plasma.  

PubMed

A gas lens is used to focus a megawatt ruby laser beam on to a target to create a plasma. By using focal plane photographs and Faraday cup plasma diagnostics, the focusing ability of a gas lens is compared with an equivalent glass lens. In this experiment the gas lens compares favorably when the laser beam has a divergence of ~1 mrad. PMID:20555544

Notcutt, M; Waltham, J A; Michaelis, M M; Cunningham, P F; Cazalet, R S

1989-07-01

9

Laser-produced plasmas in medicine  

Microsoft Academic Search

The laser has found numerous applications in medicine, beginning with uses in ophthalmology in the 1960's. Today, lasers are used in tissue cutting, blood coagulation, photo-dynamic cancer therapy, arterial plaque removal, dental drilling, etc. In this paper, we examine those areas of laser medicine in which plasmas (ionized gases) are produced. In fact, the presence of a plasma is essential

Steven J. Gitomer; Roger D. Jones

1990-01-01

10

Double layers in laser-produced plasmas  

NASA Astrophysics Data System (ADS)

Double layers (DLs) are defined as discontinuities in the plasma potential and are related to regions of plasma without space charge neutrality. In this review the knowledge of double layers in laser-produced plasmas is summarized. It has been shown that DLs are generated in the coronal or outer region of the laser-plasma system. The space charges there were detected experimentally. The simultaneous existence of “hot” electrons and “cold” electrons may induce rarefaction shock waves with discontinuities in the plasma potential. There have been indirect measurements of this phenomenon in the expanding corona of laser-heated plasmas when the ratio of the electron temperatures exceeds an order of magnitude. The energy transport and the laser absorption processes are strongly related to the density, temperature and potential structure at the critical density. Experiments and simulations show steep profile jumps at the critical surface with regions of nearly uniform profiles above and below the jump. These steep profiles are intimately related to the existence of double layers at the critical surface. Poisson's equation implies a self-consistent electric field even for neutral plasmas; this neutrality condition limits the possible DL solutions and, in particular, the discontinuities in the plasma potential cannot be treated properly with the assumption of charge neutrality. Therefore, we report on discussions of generalized analytical models and numerical hydrodynamic simulations for electrons and ions coupled by the Poissin equation, so that the space charge quasi-neutrality is no longer assumed. This is a further example of how a generalization of plasma theory was enforced by the problems of laser interaction. The fast electrons generated by the laser field in the plasma create electric fields by charge separation which accelerate positive ions. Fast electron and ion generation is a characteristic effect observed in plasmas produced by high irradiance lasers. The possibility of two-temperature electron distributions, the generation of cavitons and of fast ions and the development of DLs in laser-produced plasma seem to be correlated phenomena. Further results on second harmonics generation resonances, the unexpected phenomenon of surface tension of plasmas with stabilizing forces, and pseudo-Langmuir waves were derived from the DL studies.

Eliezer, S.; Hora, H.

1989-01-01

11

Tholins produced by a RF plasma  

NASA Astrophysics Data System (ADS)

Photochemistry by solar photons induces the formation of solid aerosols in the atmosphere of Titan. During the descent of the probe Huygens in 2005, a lot of data were collected. Among these data, the interesting ones for Titan's aerosols were produced by : i) the DISR experiment that provided optical data on the aerosols and on Titan's surface; ii) the ACP experiment, which provided compositional aerosols data [2]; iii) the HASI experiment [3] which measures the electrical properties of Titan's ground. Some properties of Titan's aerosols have been already deduced from Huygens data. However, a lot of data remains difficult to be interpreted without reference. These data do not allow to understand the formation of Titan's aerosols. Laboratory simulations of the chemical-physics of Titan's atmosphere are thus of primary interest. The equivalents of Titan's aerosols produced in laboratory are named tholins. Up to now, most of tholins are produced as films deposited on solid surfaces. They do not reproduce the fractal form of Titan's aerosols, and solid substrate can influence the chemistry. The SA team has started to produce analogues of Titan's aerosols in laboratory, using a Radio-Frequency (RF) Capacitively Coupled Plasma (CCP). This kind of plasma produces solid particles in the gas phase. It also allows producing sufficient amounts of tholins which can be provided to laboratories collaborating in the field of planetology/astrobiology. We present the correlations between the plasma conditions and tholins properties.

Alcouffe, G.; Ouni, F.; Hadamcik, E.; Szopa, C.; Cernorgora, G.

2007-08-01

12

Adventures in Laser Produced Plasma Research  

SciTech Connect

In the UK the study of laser produced plasmas and their applications began in the universities and evolved to a current system where the research is mainly carried out at the Rutherford Appleton Laboratory Central Laser Facility ( CLF) which is provided to support the universities. My own research work has been closely tied to this evolution and in this review I describe the history with particular reference to my participation in it.

Key, M

2006-01-13

13

ccsd00001732, Development behavior of liquid plasma produced by  

E-print Network

ccsd­00001732, version 2 ­ 7 Nov 2004 Development behavior of liquid plasma produced by YAG laser behavior of liquid plasma produced by YAG laser 2 NaCl is used as a test liquid. The YAG laser light development is compared with the theory. 3.2. Plasma number The number of backward plasma produced

14

Plasma injector to initiate breakdown in SSPX  

NASA Astrophysics Data System (ADS)

A plasma injector is being developed for the SSPX (Sustained Spheromak Physics Experiment). The injector will provide a plasma pulse, which will initiate ionization of gas in the gun, and is expected to provide much better control over formation, fueling, and density. The previous method relied solely on gas injection. This prototype injector is based on a design used at the University of Wisconsin at Madison and has been modified for employment on the SSPX. Injected plasma is created by a pulsed high current, high-pressure gas discharge. In addition to the injector, a compact and flexible gas valve with variable gas-pulse duration is being investigated to supply gas to the injector.

Coleman, J. E.; Morse, E. C.; McLean, H. S.; Hooper, E. B.; Hill, D. N.; Wood, R. D.

2004-11-01

15

Magnetic reconnection between colliding magnetized laser-produced plasma plumes.  

PubMed

Observations of magnetic reconnection between colliding plumes of magnetized laser-produced plasma are presented. Two counterpropagating plasma flows are created by irradiating oppositely placed plastic (CH) targets with 1.8-kJ, 2-ns laser beams on the Omega EP Laser System. The interaction region between the plumes is prefilled with a low-density background plasma and magnetized by an externally applied magnetic field, imposed perpendicular to the plasma flow, and initialized with an X-type null point geometry with B=0 at the midplane and B=8??T at the targets. The counterflowing plumes sweep up and compress the background plasma and the magnetic field into a pair of magnetized ribbons, which collide, stagnate, and reconnect at the midplane, allowing the first detailed observations of a stretched current sheet in laser-driven reconnection experiments. The dynamics of current sheet formation are in good agreement with first-principles particle-in-cell simulations that model the experiments. PMID:25238366

Fiksel, G; Fox, W; Bhattacharjee, A; Barnak, D H; Chang, P-Y; Germaschewski, K; Hu, S X; Nilson, P M

2014-09-01

16

Laser produced plasmas in medicine. II. Properties and effects  

Microsoft Academic Search

Summary form only given. In order to better understand laser-produced plasmas and their effects, researchers have performed experiments in fluids and in vitro on human stones and arterial samples. These plasmas have been studied with regard to production thresholds, temperatures and densities, optical emission, shock waves, acoustic transients, and cavitation bubbles. In addition, the effects of the laser-produced plasmas on

S. J. Gitomer; R. D. Jones

1990-01-01

17

An investigation of the structure of plasma produced by reflected shock waves  

Microsoft Academic Search

Space and time resolved measurements of electron density and temperature have been made in the reflected shock plasma produced by a Mach 20 incident shock wave propagating in argon at an initial pressure of 1.5 Torr. The peak electron density was found to decrease away from the reflecting wall in such a way that the plasma was fairly uniform at

M. G. R. Phillips; A. A. Pugatschew

1980-01-01

18

Microwave produced plasma in a Toroidal Device  

NASA Astrophysics Data System (ADS)

A currentless toroidal plasma device exhibits a large range of interesting basic plasma physics phenomena. Such a device is not in equilibrium in a strict magneto hydrodynamic sense. There are many sources of free energy in the form of gradients in plasma density, temperature, the background magnetic field and the curvature of the magnetic field. These free energy sources excite waves and instabilities which have been the focus of studies in several devices in last two decades. A full understanding of these simple plasmas is far from complete. At Utah State University we have recently designed and installed a microwave plasma generation system on a small tokamak borrowed from the University of Saskatchewan, Saskatoon, Canada. Microwaves are generated at 2.45 GHz in a pulsed dc mode using a magnetron from a commercial kitchen microwave oven. The device is equipped with horizontal and vertical magnetic fields and a transformer to impose a toroidal electric field for current drive. Plasmas can be obtained over a wide range of pressure with and without magnetic fields. We present some preliminary measurements of plasma density and potential profiles. Measurements of plasma temperature at different operating conditions are also presented.

Singh, A. K.; Edwards, W. F.; Held, E. D.

2010-11-01

19

Oxide cathodes produced by plasma deposition  

SciTech Connect

These are two distinct applications for high-current-density, long-life thermionic cathodes. The first application is as a substitute for explosive emission cathodes used in high-power microwave (HPM) devices being developed for Air Force programs. The second application is in SLAC`s X-band klystrons for the Next Linear Collider (NLC). SLAC, UCD, and LBL are developing a plasma deposition process that eliminates the problems with binders, carbonate reduction, peeling, and porosity. The emission layer is deposited using plasma deposition of metallic barium in vacuum with an oxygen background gas. An applied bias voltage drives the oxide plasma into the nickel surface. Since the oxide is deposited directly, it does not have problems with poisoning from a hydrocarbon binder. The density of the oxide layer is increased from the 40--50% for standard oxide cathodes to nearly 100% for plasma deposition.

Scheitrum, G.; Caryotakis, G. [Stanford Linear Accelerator Center, Menlo Park, CA (United States); Pi, T.; Umstattd, R. [Univ. of California, Davis, CA (United States); Brown, I.; Montiero, O. [Lawrence Berkeley Lab., CA (United States)

1997-12-31

20

The effect of excitation wavelength on dynamics of laser-produced tin plasma  

SciTech Connect

We investigated the effect of the excitation wavelength on the density evolution of laser-produced tin plasmas, both experimentally and numerically. For producing plasmas, Sn targets were excited with either 10.6 {mu}m CO{sub 2} laser or 1.06 {mu}m Nd:yttrium aluminum garnet laser; both are considered to be potential excitation lasers for extreme ultraviolet lithography laser-produced plasma light sources. The electron density of the plasma during the isothermal expansion regime was estimated using an interferometric technique. The Stark broadening of isolated singly-ionized emission was employed for deducing the density during the plasma adiabatic expansion regime. Our results indicate that the excitation source wavelength determines the initial density of the plasma, as well the plume expansion dynamics. Numerical simulation using HEIGHTS simulation package agrees well with the experimentally measured density profile.

Harilal, S. S.; Sizyuk, T.; Hassanein, A.; Campos, D.; Sizyuk, V. [School of Nuclear Engineering and Center for Materials Under Extreme Environment, Purdue University, 400 Central Dr., West Lafayette, Indiana 47907 (United States); Hough, P. [School of Physical Sciences and National Centre for Plasma Science and Technology, Dublin City University, Glasnevin, Dublin 9 (Ireland)

2011-03-15

21

Experiments on Initial Formation of Plasma Flow Switches.  

NASA Astrophysics Data System (ADS)

Plasma flow switches have been used to shorten the current pulse for inductive storage capacitor banks to implode plasmas for producing radiation.(J.H.Degnan, et.al., IEEE Trans. Plasma Sci., PS-15, 760(1987).)They consist of two components, an aluminum wire array and a plastic barrier film separated by a few mm. We have performed a series of experiments at Los Alamos to understand the sensitivity of the performance of plasma flow switches to their initial conditions. These experiments were done on two facilities, one a 250 kJ capacitor bank called the Colt facility with a maximum current of 1.0 MA in 2.5 microseconds. The other is the Pegasus II facility with a maximum current of 10 MA in a time of 4 microseconds. The overall performance of the switch as determined by the voltage developed was measured as a function of the mass of the switch, the distribution of the mass among the switch components, and the separation of the components. A preliminary understanding of the important parameters and the physical basis for their importance will be given. (This worked performed under the auspices of the Department of Energy.)

Benage, John F., Jr.; Bowers, Richard; Oona, Hank; Wysocki, Fred; Broste, William B.; Harper, Ron; Roderick, Norm

1996-11-01

22

Analysis of the Inverted Double Layers Produced by Nonlinear Forces in a Laser-Produced Plasma  

Microsoft Academic Search

By use of a hydrocode it is shown that the interaction of high-intensity light with an expanding plasma surface produces a positive plasma cloud followed by a negative plasma cloud. This result, which is opposite to that without the laser light, is the result of the non-linear (ponderomotive) force.

Heinrich Hora; Paraskevas Lalousis; Shalom Eliezer

1984-01-01

23

Light source employing laser-produced plasma  

DOEpatents

A system and a method of generating radiation and/or particle emissions are disclosed. In at least some embodiments, the system includes at least one laser source that generates a first pulse and a second pulse in temporal succession, and a target, where the target (or at least a portion the target) becomes a plasma upon being exposed to the first pulse. The plasma expand after the exposure to the first pulse, the expanded plasma is then exposed to the second pulse, and at least one of a radiation emission and a particle emission occurs after the exposure to the second pulse. In at least some embodiments, the target is a solid piece of material, and/or a time period between the first and second pulses is less than 1 microsecond (e.g., 840 ns).

Tao, Yezheng; Tillack, Mark S

2013-09-17

24

Ablation and plasma emission produced by dual femtosecond laser pulses  

NASA Astrophysics Data System (ADS)

Pairs of 80fs, 800nm laser pulses were used to ablate Si, Cu, and CaF2 in air. The spectrally resolved plasma emission was measured as a function of laser fluence and pulse delay. After an initial dip, the fluorescence was found to increase monotonically with pulse delay, reaching a plateau after some tens of picoseconds, depending on the material and fluence. The enhancement ratio (defined as the ratio of the fluorescence produced by the pulse pair to that produced by a single pulse of the same total fluence) reaches a maximum value of 6 and 11 at a fluence of ˜6J /cm2 for Si and Cu, respectively, and declines to a value below 2 at higher fluences. In contrast, the enhancement for CaF2 increases slowly from zero near threshold to a broad maximum value of 2 near 50J /cm2. Using reflectivity and atomic force microscopy measurements as diagnostics, we interpret the Si and Cu behavior in terms of a two phase mechanism, in which the first pulse melts the surface of the crystal and the second pulse ablates the resulting liquid film. A qualitatively different mechanism initiated by multiphoton absorption is involved in CaF2 ablation.

Singha, Sima; Hu, Zhan; Gordon, Robert J.

2008-12-01

25

Laser produced plasma for efficient extreme ultraviolet light sources  

SciTech Connect

Extreme ultraviolet emission from laser produced plasma and their relevance to EUV source development is discussed. The current state of the field for Sn LPP sources operating at 13.5 nm is described and initial results are given for EUV emission from CO{sub 2} laser irradiation of a bulk Sn target. A maximum conversion efficiency of 1.7% has been measured and the influence of the CO{sub 2} laser temporal profile on the CE is discussed. A double pulse irradiation scheme is shown to increase CE up to a maximum value of 2.1% for an optimum prepulse - pulse delay of 150 ns. The emergence of a new EUVL source wavelength at 6.7 nm based on Gd and Tb LPPs has been outlined. An initial experiment investigating picosecond laser irradiation as a means to produce strong 6.7 nm emission from a Gd{sub 2}O{sub 3} target has been performed and verified.

Donnelly, Tony; Cummins, Thomas; O' Gorman, Colm; Li Bowen; Harte, Colm S.; O'Reilly, Fergal; Sokell, Emma; Dunne, Padraig; O'Sullivan, Gerry [School of Physics, University College Dublin, Belfield, Dublin 4 (Ireland)

2012-05-25

26

Laser-pulsed plasma chemistry: Laser-initiated plasma oxidation of niobium  

Microsoft Academic Search

We report the first observation of the chemical modification of a solid surface exposed to an ambient gas plasma initiated by the interaction of laser radiation with the same surface. A new technique, which we designate laser-pulsed plasma chemistry (LPPC), is proposed for activating heterogeneous chemical reactions at solid surfaces in a gaseous ambient by means of a plasma initiated

R. F. Marks; R. A. Pollak; Ph. Avouris; C. T. Lin; Y. J. The´faine

1983-01-01

27

Attenuated APC alleles produce functional protein from internal translation initiation  

PubMed Central

Some truncating mutations of the APC tumor suppressor gene are associated with an attenuated phenotype of familial adenomatous polyposis coli (AAPC). This work demonstrates that APC alleles with 5? mutations produce APC protein that down-regulates ?-catenin, inhibits ?-catenin/T cell factor-mediated transactivation, and induces cell-cycle arrest. Transfection studies demonstrate that cap-independent translation is initiated internally at an AUG at codon 184 of APC. Furthermore, APC coding sequence between AAPC mutations and AUG 184 permits internal ribosome entry in a bicistronic vector. These data suggest that AAPC alleles in vivo may produce functional APC by internal initiation and establish a functional correlation between 5? APC mutations and their associated clinical phenotype. PMID:12034871

Heppner Goss, Kathleen; Trzepacz, Chris; Tuohy, Thérèse M. F.; Groden, Joanna

2002-01-01

28

Intense terahertz emission from atomic cluster plasma produced by intense femtosecond laser pulses  

SciTech Connect

Terahertz (THz) emission from argon cluster plasma, generated by intense femtosecond laser pulses in the energy range of 10-70 mJ, has been investigated. THz polarization, energy dependence, and angular distribution were measured to provide an initial discussion on the mechanisms of THz emission. THz pulses of much higher energy were generated from argon clusters than from argon gas, which indicates that plasma produced from atomic clusters holds considerable promise as an intense THz source.

Jahangiri, Fazel; Hashida, Masaki; Tokita, Shigeki; Sakabe, Shuji [Advanced Research Center for Beam Science, ICR, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan and Department of Physics, GSS, Kyoto University, Kitashirakawa, Sakyo, Kyoto 606-7501 (Japan); Nagashima, Takeshi; Hangyo, Masanori [Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871 (Japan)

2011-12-26

29

Plasma waves near Saturn: initial results from Voyager 1  

Microsoft Academic Search

The Voyager 1 encounter with Saturn provided the first opportunity to investigate plasma wave interactions in the magnetosphere of Saturn. An overview of the principal results from the Voyager 1 plasma wave instrument is presented starting with the initial detection of Saturn and ending about four weeks after closest approach. A survey plot of the electric field intensities detected during

D. A. Gurnett; W. S. Kurth; F. L. Scarf

1981-01-01

30

A new method to produce an annular cylindrical plasma for imploding plasma experiments  

NASA Astrophysics Data System (ADS)

A new method to produce a hollow cylindrical metallic plasma is presented. A metallic foil is exploded by discharging a capacitor bank; the vapor which is produced expands through an annular diaphragm and forms a cylindrical shell of weakly ionized gas, which can be imploded to produce a hot, dense plasma, resulting in a high-power soft X-ray pulse. The density of the hollow cylindrical plasma is measured by resonant interferometry, a new and powerful diagnostic for probing the plasma mass density before the compression (neutral density approximately 10 to the 16th per cu cm). The device is complementary to supersonic gas-puff or exploding wires experiments.

Gazaix, M.; Doucet, H. J.; Etlicher, B.; Lamain, H.; Rouille, C.; Furtlehner, J. P.

1984-12-01

31

Experimental and theoretical aspects of a laser produced plasma  

NASA Astrophysics Data System (ADS)

We report certain complex behaviors of a nanosecond Nd:YAG laser produced plasma on a Ni target. For high laser fluences, a split in the transversal expansion plane along with oscillatory regimes of the ablation plasma were observed and investigated. These complex phenomena, which take place at various interaction time scales, are described using a fractal theoretical model based on continuous but non-differentiable curves of particle movement.

Irimiciuc, ?. A.; Mih?il?, I.; Agop, M.

2014-09-01

32

Non-equilibrium Ta plasmas produced by fast pulsed lasers  

NASA Astrophysics Data System (ADS)

A Nd:YAG laser, 9 ns pulse width, 30 Hz repetition rate, a maximum pulse density of 10 10 W/cm 2 and an iodine laser, 400 ps pulse, operating in single pulse width with a maximum power density of 10 16 W/cm 2, are employed to produce pulsed plasmas in vacuum. A comparison of the results obtained for the ablation of tantalum targets is presented, including the ablation yields, the ion and neutral emissions and the angular distributions. A plasma plume is produced along the normal to the target surface; it expands adiabatically at supersonic velocity carrying neutral and charged particles and emits visible light, UV and X-rays as well. The plasma has been characterised in terms of an equivalent ion and electron temperature (˜10 7 K), density (˜10 17 cm -3), and fractional ionisation, which is proportional to the laser intensity. A special attention is devoted to the ion production and to ion kinetic energy, which can reach values of the order of 1 MeV. Such an ion acceleration is due to high electric fields generated inside the non-equilibrium plasma, which can reach values of the order of GV/cm at high laser intensities. Finally, some applications of the laser-produced plasma for the ion injection into ion sources and for the multi-energetic ion implantation plasma-laser are presented.

Torrisi, L.; Gammino, S.

2006-01-01

33

Using Laser-produced Plasmas to Study Magnetized Collisionless Shocks  

NASA Astrophysics Data System (ADS)

A new laser experiment to study the interaction of an energetic laser plasma with a large magnetized ambient plasma is now operational at the Large Plasma Device (LAPD) at UCLA. A rapidly exploding, and super-Alfvénic (MA>2) plasma-plume is created by irradiating a solid target within the preformed magnetized plasma with an energetic laser pulse (200 J in 20 ns). The ambient plasma (1013 cm-3, 5 eV) is current free, stationary, quiescent, and large enough (17x0.5 m) to support Alfvén waves. The dynamics of the laser-plasma piston and formation and structure of the shock is measured with magnetic flux-probes, spectroscopy, and Thomson scattering. We observe how the initial magnetic pulse steepens into a collisionless shock and separates from the piston by several ion Larmor radii. Hybrid simulations indicate that these features can be directly related to the degree of collisionless plasma coupling. The results will be discussed in the context of debris-ambient coupling in space and astrophysical explosions and other laboratory experiments.

Niemann, Christoph; Schaeffer, Derek; Everson, Erik; Clark, E.; Bondarenko, Anton; Constantin, Carmen; Gekelman, Walter; Winske, Dan

2014-06-01

34

Ramp-up of CHI Initiated Plasmas on NSTX  

SciTech Connect

Experiments on the National Spherical Torus (NSTX) have now demonstrated flux savings using transient coaxial helicity injection (CHI). In these discharges, the discharges initiated by CHI are ramped up with an inductive transformer and exhibit higher plasma current than discharges without the benefit of CHI initiation.

Mueller, D; Bell, R E; LeBlanc, B; Roquemore, A L; Raman, R; Jarboe, T R; Nelson, B A

2009-10-29

35

Plasma double-layers produced by ponderomotive force  

NASA Technical Reports Server (NTRS)

Non-linear rectification of the RF electric fields excited in a convectively amplifying electron beam-plasma interaction results in a dc electric field, and a corresponding ponderomotive force acting on the charged particles to produce a space-charge separation, i.e. a type of plasma double-layer. This paper analyses the effect, taking into account plasma electron temperature and electron-neutral collisions. To measure such double-layers, an electron beam probe constitutes a convenient non-perturbing diagnostic technique, but great care is required in its calibration. An analysis is presented taking into account significant non-linear effects which had been neglected in previous work. The paper concludes with some preliminary experimental results illustrating the use of the technique in a beam-plasma interaction for which a weak double-layer electric field is predicted.

Levine, J. S.; Crawford, F. W.

1980-01-01

36

Relativistic Electromagnetic Solitons Produced by Ultrastrong Laser Pulses in Plasmas  

NASA Astrophysics Data System (ADS)

Low frequency, relativistic sub-cycle localised (soliton-like) concentrations of the electromagnetic (em) energy are found in two-dimensional (2D) and in three-dimensional (3D) Particle in Cell simulations of the interaction of ultra-short, high-intensity laser pulses with homogeneous and inhomogeneous plasmas. These solitons consist of electron and ion density depressions and intense em field concentrations with a frequency definitely lower than that of the laser pulse. The downshift of the pulse frequency, due to the depletion of the pulse energy, causes a significant portion of the pulse em energy to become trapped as solitons, slowly propagating inside the plasma. In an earlier phase solitons are formed due to the trapping of the em radiation inside an electron cavity, while ions can be assumed to remain at rest. Later on, after (mi/me)1/2 times the laser period, ions start to move and the ion depletion occurs producing a slowly growing hole in the plasma density. In inhomogeneous plasmas the solitons are accelerated toward the plasma vacuum interface where they radiate away their energy in the form of bursts of low frequency em radiation. In the frame of a 1D cold hydrodynamic model for an electron-ion plasma, the existence of multipeaked em solitons has been investigated both analytically and numerically. The analytical expression for a sub-cycle relativistic soliton has been derived for circularly polarized pulses in a cold isotropic plasma, and in the presence of an externally applied magnetic field. Recently, em relativistic solitons in a hot multi-component plasma have been investigated in the frame of an hydrodynamic (adiabatic) model and of a kinetic (isothermal) model. An overview of the most recent analytical and numerical results on the soliton dynamics is given.

Lontano, M.; Bulanov, S. V.; Califano, F.; Esirkepov, T. Zh.; Farina, D.; Koga, J.; Liseikina, T. V.; Mima, K.; Nakajima, K.; Naumova, N. M.; Nishihara, K.; Passoni, M.; Pegoraro, F.; Ruhl, H.; Sentoku, Y.; Tajima, T.; Vshivkov, V. A.

2002-10-01

37

Transient processes in plasmas produced by surface waves  

NASA Astrophysics Data System (ADS)

The rise time of a wave electric field tau(HF) and the ionization front velocity nu(f) are measured in a pulsed plasma produced by a surface wave. Different behaviors of tau(HF) and nu(f) are observed when the pressure is varied. The passage from a collisional to a non-collisional mode may be identified, in accordance with the electronic mean free path estimated for the discharge. The variations of nu(f) and tau(HF) with power corroborate this classification. The electron density along the plasma column is also measured for different instants tau(i) from the beginning of the pulse. Thus the discharge stabilization can be identified by its behavior in analogy with the stationary plasma.

Llamas, M.; Rodriguez-Vidal, M.; Colomer, V.

1985-11-01

38

Electrostatic instabilities in circularly polarized microwave produced magnetized plasmas  

SciTech Connect

The growth rate of electrostatic instabilities of electron oscillation and low-frequency (LF) ion oscillation are investigated for a plasma produced by a circularly polarized microwave field during the breakdown process. The plasma is magnetized by an external homogenous static magnetic field on the direction of microwave field propagation. Numerical calculations show that the electron and ion perturbations are unstable in such an anisotropic plasma. Electron perturbations have the maximum growth rate across the magnetic field. In addition, ion perturbation growth rate is minimum on this direction. The LF ion oscillation is excited by Cherenkov emission mechanism due to the nonequilibrium form of the electron velocity distribution function. Electron oscillation growth rate decreases by increasing the external magnetic field, while the LF ion oscillation increases smoothly and reaches a maximum when the electron oscillation is stopped.

Ghorbanalilu, M. [Department of Physics, Azarbaijan University of Tarbiat Moallem, Tabriz, Iran and Research Institute of Astronomy and Astrophysics of Maragha, P.O. Box 55134-44, Maragha (Iran, Islamic Republic of); Shokri, B. [Department of Physics and Laser-Plasma Research Institute, Shahid Beheshti University, G. C., Evin, Tehran (Iran, Islamic Republic of)

2009-12-15

39

Plasma irregularities in the D-region ionosphere in association with sprite streamer initiation  

NASA Astrophysics Data System (ADS)

Sprites are spectacular optical emissions in the mesosphere induced by transient lightning electric fields above thunderstorms. Although the streamer nature of sprites has been generally accepted, how these filamentary plasmas are initiated remains a subject of active research. Here we present observational and modelling results showing solid evidence of pre-existing plasma irregularities in association with streamer initiation in the D-region ionosphere. The video observations show that before streamer initiation, kilometre-scale spatial structures descend rapidly with the overall diffuse emissions of the sprite halo, but slow down and stop to form the stationary glow in the vicinity of the streamer onset, from where streamers suddenly emerge. The modelling results reproduce the sub-millisecond halo dynamics and demonstrate that the descending halo structures are optical manifestations of the pre-existing plasma irregularities, which might have been produced by thunderstorm or meteor effects on the D-region ionosphere.

Qin, Jianqi; Pasko, Victor P.; McHarg, Matthew G.; Stenbaek-Nielsen, Hans C.

2014-05-01

40

Plasma irregularities in the D-region ionosphere in association with sprite streamer initiation.  

PubMed

Sprites are spectacular optical emissions in the mesosphere induced by transient lightning electric fields above thunderstorms. Although the streamer nature of sprites has been generally accepted, how these filamentary plasmas are initiated remains a subject of active research. Here we present observational and modelling results showing solid evidence of pre-existing plasma irregularities in association with streamer initiation in the D-region ionosphere. The video observations show that before streamer initiation, kilometre-scale spatial structures descend rapidly with the overall diffuse emissions of the sprite halo, but slow down and stop to form the stationary glow in the vicinity of the streamer onset, from where streamers suddenly emerge. The modelling results reproduce the sub-millisecond halo dynamics and demonstrate that the descending halo structures are optical manifestations of the pre-existing plasma irregularities, which might have been produced by thunderstorm or meteor effects on the D-region ionosphere. PMID:24806314

Qin, Jianqi; Pasko, Victor P; McHarg, Matthew G; Stenbaek-Nielsen, Hans C

2014-01-01

41

Plasma-puff initiation of high Coulomb transfer switches  

NASA Technical Reports Server (NTRS)

The plasma-puff triggering mechanism based on a hypocycloidal pinch geometry was investigated to determine the optimal operating conditions for an azimuthally uniform surface flashover which initiates plasma-puff under wide ranges of fill gas pressures of Ar, He and N2. The optimal fill gas pressures for the azimuthally uniform plasma-puff were about 120 mTorr less than P(opt) less than 450 Torr for He and N2. For Argon 120 mTorr less than P(opt) less than 5 Torr for argon. The inverse pinch switch was triggered with the plasma-puff and the switching capability under various electrical parameters and working gas pressures of Ar, He and N2 was determined. It was also shown that the azimuthally uniform switching discharges were dependent on the type of fill gas and its fill pressure. A new concept of plasma-focus driven plasma-puff was also discussed in comparison with hypocycloidal pinch plasma-puff triggering. The main discharge of the inverse pinch switch with the plasma-focus driven plasma-puff trigger is found to be more azimuthally uniform than that with the hypocycloidal pinch plasma-puff trigger in a gas pressure region between 80 mTorr and 1 Torr. In order to assess the effects of plasma current density on material erosion of electrodes, emissions from both an inverse-pinch plasma switch (INPIStron) and from a spark gap switch under test were studied with an optical multichannel analyzer (OMA). The color temperature of the argon plasma was approximately 4,000 K which corresponded with the peak continuum emission near 750 nm. There are the strong line emissions of argon in the 650 - 800 nm range and a lack of line emissions of copper and other solid material used in the switch. This indicates that the plasma current density during closing is low and the hot spot or hot filament in the switch is negligible. This result also indicates considerable reduction of line emission with the INPIStron switch over that of a spark-gap switch. However, a strong carbon line emission exists due to vaporization of the plastic insulator used. In order to reduce the vaporization of the insulator, the plexiglass insulating material of INPIStron was replaced with Z-9 material. A comparative study of the INPIStron and a spark gap also reveals that the INPIStron, with a low impedance of Z equals 9 ohms, can transfer a high voltage pulse with a superior pulse-shape fidelity over that of a spark gap with Z equals 100 ohms.

Venable, D. D.; Han, K. S.

1993-01-01

42

Plasma-puff initiation of high Coulomb transfer switches  

NASA Technical Reports Server (NTRS)

The plasma-puff triggering mechanism based on a hypocycloidal pinch geometry was investigated to determine the optimal operating conditions for an azimuthally uniform surface flashover which initiates plasma-puff under wide ranges of fill gas pressures of Ar, He and N2. The optimal fill gas pressures for the azimuthally uniform plasma-puff were about 120 mTorr less than P(sub opt) less than 450 Torr for He and N2. For Argon 20 mTorr is less than P(sub opt) is less than 5 Torr. The inverse pinch switch was triggered with the plasma-puff and the switching capability under various electrical parameters and working gas pressures of Ar, He and N2 was determined. It was also shown that the azimuthally uniform switching discharges were dependent on the type of fill gas and its fill pressure. A new concept of plasma-focus driven plasma-puff was also discussed in comparison with hypocycloidal pinch plasma-puff triggering. The main discharge of the inverse pinch switch with the plasma-focus driven plasma-puff trigger is found to be more azimuthally uniform than that with the hypocycloidal pinch plasma-puff trigger in a gas pressure region between 80 mTorr and 1 Torr. In order to assess the effects of plasma current density on material erosion of electrodes, emissions from both an inverse-pinch plasma switch (INPIStron) and from a spark gap switch under test were studied with an optical multichannel analyzer (OMA). The color temperature of the argon plasma was approximately 4,000 K which corresponded with the peak continuum emission near 750 nm. There are the strong line emissions of argon in the 650 - 800 nm range and a lack of line emissions of copper and other solid material used in the switch. This indicates that the plasma current density during closing is low and the hot spot or hot filament in the switch is negligible. This result also indicates considerable reduction of line emission with the INPIStron switch over that of a spark-gap switch. However, a strong carbon line emission exists due to vaporization of the plastic insulator used. In order to reduce the vaporization of the insulator, the plexiglass insulating material of INPIStron was replaced with Z-9 material. A comparative study of the INPIStron and a spark gap also reveals that the INPIStron, with a low impedance of Z = 9 ohms, can transfer a high voltage pulse with a superior pulse-shape fidelity over that of a spark gap with Z = 100 ohms.

Han, Kwang S.; Venable, Demetrius D.; Lee, Ja H.; Choi, Eun H.; Kim, Y. K.; Kim, J. H.; Nguyen, D. X.

1993-01-01

43

Thermalization of anisotropic quark-gluon plasma produced by decays of color flux tubes  

NASA Astrophysics Data System (ADS)

Kinetic equations are used to study the thermalization of an anisotropic quark-gluon plasma produced by decays of color flux tubes possibly created during the very early stages of relativistic heavy-ion collisions. The decay rates of the initial color tubes are given by the Schwinger formula, while the collision terms are taken in the relaxation time approximation. By connecting the relaxation time with viscosity we analyze production and thermalization processes in the plasma characterized by different values of the ratio of the shear viscosity to entropy density.

Florkowski, Wojciech; Ryblewski, Radoslaw

2014-11-01

44

Charge-exchange collisions in interpenetrating laser-produced magnesium plasmas  

E-print Network

Charge-exchange collisions in interpenetrating laser-produced magnesium plasmas S.S. HARILAL,1 C charge-exchange collisions between highly charged Mg ions in colliding laser-produced magnesium plasmas magnesium plasmas. 1. INTRODUCTION Several applications of laser-produced plasmas involve an experimental

Harilal, S. S.

45

ccsd-00001732,version2-7Nov2004 Development behavior of liquid plasma produced by  

E-print Network

ccsd-00001732,version2-7Nov2004 Development behavior of liquid plasma produced by YAG laser Jun behavior of liquid plasma produced by YAG laser 2 NaCl is used as a test liquid. The YAG laser light is compared with the theory. 3.2. Plasma number The number of backward plasma produced by fundamental wave

Paris-Sud XI, Université de

46

Microwave Reflection Measurements of Electron Densities in Electromagnetically Driven Shock-Produced Plasmas  

Microsoft Academic Search

The electron densities from 1013 to 1017 cm?3 in plasmas produced by electromagnetically driven, propagating, or reflected shock waves are measured by a microwave reflection method. The Mach number of the shock waves is varied from 9 to 25 in argon, air, and helium at initial pressures from 0.4 to 2.0 Torr. A 35-GHz microwave reflection probe is inserted into

Akimasa Funahashi; Susumu Takeda

1968-01-01

47

Plasma observations near Saturn - Initial results from Voyager 2  

NASA Technical Reports Server (NTRS)

Results of plasma measurements made by Voyager 2 in the vicinity of Saturn are discussed and compared with those made by Pioneer 11 and Voyager 1 in a more limited range of latitudes. The initial bow shock crossing on the inbound trajectory closely agreed with the shock position inferred from the external ram pressure in the solar wind, although boundaries on the outbound pass were much further out than expected. Magnetospheric plasma observations reveal the presence of (1) shocked solar wind plasma in the magnetosheath between 30 and 22 Saturn radii; (2) a variable density region between 17 Saturn radii and the magnetopause; (3) an extended thick plasma sheet between 17 and 7 Saturn radii; and (4) an inner plasma torus probably originating from local sources. The ratio of heavy to light ions was observed to vary with distance to the equatorial plane in the dayside magnetosphere, with the heavy ions, probably O(+), more closely confined to the equatorial plane. The plasma data also account for the observed inner boundary of the neutral hydrogen torus discovered by Voyager 1.

Bridge, H. S.; Bagenal, F.; Belcher, J. W.; Lazarus, A. J.; Mcnutt, R. L.; Sullivan, J. D.; Gazis, P. R.; Hartle, R. E.; Ogilvie, K. W.; Scudder, J. D.

1982-01-01

48

Hydrolysis of hemicellulose to produce fermentable monosaccharides by plasma acid.  

PubMed

In this paper, plasma acid was obtained by treating distilled water with dielectric barrier discharge to hydrolyze hemicellulose. The orthogonal experiment L??(5(6)) was used to optimize such hydrolysis conditions. The total reducing sugar (TRS) was measured by the DNS method. To determine whether the oligosaccharide existed in the hydrolysis products, it was hydrolyzed by sulfuric acid for a second time following the same procedure as reported earlier. The monosaccharide compositions of the hydrolyzed sample were analyzed by high-performance liquid chromatography (HPLC) and Fourier transformed infrared spectroscopy (FTIR). The results showed that pH 2.81 of plasma acid, 100 °C and 50 min were assigned as an optimal hydrolysis condition by plasma acid. Under this condition, the hemicellulose was hydrolyzed completely to produce monosaccharides including xylose, glucose, and galactose with the mole ratio being 17:3:1. The yields of xylose, glucose, and galactose were 38.67%, 9.28% and 3.09%, respectively. Compared with the hemicellulose hydrolysis results by sulfuric acid, it is concluded that plasma acid is an environmental-friendly and efficient method to explore and hydrolyze the hemicellulose existed in biomass. PMID:23911479

Wang, Ying; Yuan, Bo; Ji, Yingchao; Li, Hong

2013-09-12

49

On a characteristic initial value problem in Plasma physics  

E-print Network

The relativistic Vlasov-Maxwell system of plasma physics is considered with initial data on a past light cone. This characteristic initial value problem arises in a natural way as a mathematical framework to study the existence of solutions isolated from incoming radiation. Various consequences of the mass-energy conservation and of the absence of incoming radiation condition are first derived assuming the existence of global smooth solutions. In the spherically symmetric case, the existence of a unique classical solution in the future of the initial cone follows by arguments similar to the case of initial data at time $t=0$. The total mass-energy of spherically symmetric solutions equals the (properly defined) mass-energy on backward and forward light cones.

Simone Calogero

2005-06-01

50

Characteristics of argon plasma waveguide produced by alumina capillary discharge for short wavelength laser application  

SciTech Connect

We have reported the argon (Ar) plasma waveguide produced in an alumina (Al{sub 2}O{sub 3}) capillary discharge and used to guide ultrashort laser pulses at intensities of the order of 10{sup 16} W/cm{sup 2}. The electron density in the plasma waveguide was measured to be 1x10{sup 18} cm{sup -3}, in agreement with one-dimensional magnetrohydrodynamic (MHD) simulations. The MHD code was also used to evaluate the degree of ionization of argon (Ar) in the preformed plasma waveguide. The maximum ion charge state of Ar{sup 3+} in capillary discharge was measured and obtained in the MHD simulations. The spectrum of the propagated laser pulse in the Ar plasma waveguide was not modified and was well reproduced by a particle-in-cell simulations under initial ion charge state of Ar{sup 3+} in the preformed plasma waveguide. The optimum timing for the laser pulse injection was around 150 ns after initiation of a discharge with a peak current of 200 A.

Higashiguchi, Takeshi; Yugami, Noboru [Department of Advanced Interdisciplinary Sciences, Center for Optical Research and Education (CORE), and Optical Technology Innovation Center (OpTIC), Utsunomiya University, Yoto 7-1-2, Utsunomiya, Tochigi 321-8585 (Japan); Japan Science and Technology Agency, CREST, 4-1-8 Honcho, Kanagawa, Saitama 332-0012 (Japan); Bobrova, Nadezhda; Sasorov, Pavel [Institute for Theoretical and Experimental Physics, B. Cheremushkinskaya Str. 25, 117218 Moscow (Russian Federation); Sakai, Shohei [Department of Advanced Interdisciplinary Sciences, Center for Optical Research and Education (CORE), and Optical Technology Innovation Center (OpTIC), Utsunomiya University, Yoto 7-1-2, Utsunomiya, Tochigi 321-8585 (Japan); Sentoku, Yasuhiko [Department of Physics, University of Nevada, Mail Stop 220, Reno, Nevada 89506 (United States); Kodama, Ryosuke [Japan Science and Technology Agency, CREST, 4-1-8 Honcho, Kanagawa, Saitama 332-0012 (Japan); Graduate School of Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan)

2012-05-01

51

Characterization of a streamer-initiated atmospheric pressure plasma jet for spatially guided pulsed plasma generation  

Microsoft Academic Search

We examine the characteristics of a streamer-initiated atmospheric pressure plasma jet (APPJ) terminated by a cathode ground plane in air. The plasma jet is generated using a 12 kV submicrosecond voltage pulse exciting a single positively biased electrode wrapped around a 3 mm diameter glass capillary with a 2 slm, 5% Ar\\/He mixture, gas flow. This APPJ device is distinguished

Brian Sands; Biswa Ganguly

2008-01-01

52

Saturation of Langmuir waves in laser-produced plasmas  

SciTech Connect

This dissertation deals with the interaction of an intense laser with a plasma (a quasineutral collection of electrons and ions). During this interaction, the laser drives large-amplitude waves through a class of processes known as parametric instabilities. Several such instabilities drive one type of wave, the Langmuir wave, which involves oscillations of the electrons relative to the nearly-stationary ions. There are a number of mechanisms which limit the amplitude to which Langmuir waves grow. In this dissertation, these mechanisms are examined to identify qualitative features which might be observed in experiments and/or simulations. In addition, a number of experiments are proposed to specifically look for particular saturation mechanisms. In a plasma, a Langmuir wave can decay into an electromagnetic wave and an ion wave. This parametric instability is proposed as a source for electromagnetic emission near half of the incident laser frequency observed from laser-produced plasmas. This interpretation is shown to be consistent with existing experimental data and it is found that one of the previous mechanisms used to explain such emission is not. The scattering version of the electromagnetic decay instability is shown to provide an enhanced noise source of electromagnetic waves near the frequency of the incident laser.

Baker, K.L.

1996-04-01

53

An investigation of the structure of plasma produced by reflected shock waves  

NASA Astrophysics Data System (ADS)

Space and time resolved measurements of electron density and temperature have been made in the reflected shock plasma produced by a Mach 20 incident shock wave propagating in argon at an initial pressure of 1.5 Torr. The peak electron density was found to decrease away from the reflecting wall in such a way that the plasma was fairly uniform at all times. Close to the reflecting wall (0.2 cm away) the measured peak electron density was close to (i.e, about 20% lower than) the predicted equilibrium value but farther away (1.0 cm) it was lower by a factor of 4. Possible reasons for this discrepancy are discussed. Calculations of reflected shock plasma structure based on incident shock structure are only partially supported by available experimental evidence.

Phillips, M. G. R.; Pugatschew, A. A.

1980-01-01

54

Observation and numerical analysis of plasma parameters in a capillary discharge-produced plasma channel waveguide  

NASA Astrophysics Data System (ADS)

We observed the parameters of the discharge-produced plasma in cylindrical capillary. Plasma parameters of the waveguide were investigated by use of both a Normarski laser interferometer and a hydrogen plasma line spectrum. A space-averaged maximum temperature of 3.3 eV with electron densities of the order of 1017 cm-3 was observed at a discharge time of 150 ns and a maximum discharge current of 200 A. One-dimensional dissipative magnetohydrodynamic (MHD) code was used to analyze the discharge dynamics in the gas-filled capillary discharge waveguide for high-intensity laser pulses. Simulations were performed for the conditions of the experiment. We compared the temporal behavior of the electron temperature and the radial electron density profiles, measured in the experiment with the results of the numerical simulations. They occurred to be in a good agreement. An ultrashort, intense laser pulse was guided by use of this plasma channel.

Terauchi, Hiromitsu; Bobrova, Nadezhda; Sasorov, Pavel; Kikuchi, Takashi; Sasaki, Toru; Higashiguchi, Takeshi; Yugami, Noboru; Kodama, Ryosuke

2011-03-01

55

Detection of electromagnetic pulses produced by hypervelocity micro particle impact plasmas  

SciTech Connect

Hypervelocity micro particles (mass < 1 ng), including meteoroids and space debris, routinely impact spacecraft and produce plasmas that are initially dense (?10{sup 28} m{sup ?3}), but rapidly expand into the surrounding vacuum. We report the detection of radio frequency (RF) emission associated with electromagnetic pulses (EMPs) from hypervelocity impacts of micro particles in ground-based experiments using micro particles that are 15 orders of magnitude less massive than previously observed. The EMP production is a stochastic process that is influenced by plasma turbulence such that the EMP detection rate that is strongly dependent on impact speed and on the electrical charge conditions at the impact surface. In particular, impacts of the fastest micro particles occurring under spacecraft charging conditions representative of high geomagnetic activity are the most likely to produce RF emission. This new phenomenon may provide a source for unexplained RF measurements on spacecraft charged to high potentials.

Close, Sigrid; Lee, Nicolas; Johnson, Theresa; Goel, Ashish; Fletcher, Alexander [Department of Aeronautics and Astronautics, Stanford University, Stanford, California 94305 (United States)] [Department of Aeronautics and Astronautics, Stanford University, Stanford, California 94305 (United States); Linscott, Ivan; Strauss, David; Lauben, David [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States)] [Department of Electrical Engineering, Stanford University, Stanford, California 94305 (United States); Srama, Ralf; Mocker, Anna; Bugiel, Sebastian [Institut für Raumfahrtsysteme, Universität Stuttgart, Pfaffenwaldring 29, 70569 Stuttgart (Germany)] [Institut für Raumfahrtsysteme, Universität Stuttgart, Pfaffenwaldring 29, 70569 Stuttgart (Germany)

2013-09-15

56

Plasma waves near Saturn: Initial results from Voyager 1  

NASA Technical Reports Server (NTRS)

The Voyager 1 encounter with Saturn provided the first opportunity to investigate plasma wave interactions in the magnetosphere of Saturn. An overview of the principal results from the Voyager 1 plasma wave instrument is presented starting with the initial detection of Saturn and ending about four weeks after closest approach. A survey plot of the electric field intensities detected during the Saturn encounter is shown starting shortly before the inbound shock crossing and ending shortly after the outbound magnetopause crossing. Many intense waves were observed in the vicinity of Saturn. To provide a framework for presenting the observations, the results are discussed more or less according to the sequence in which the data were obtained.

Gurnett, D. A.; Kurth, W. S.; Scarf, F. L.

1981-01-01

57

Producing the Initial State of X1 Cryogenic ICF Targets  

NASA Astrophysics Data System (ADS)

The proposed X1 Advanced Radiation Source is an enlarged version of Sandia National Laboratories' Z pulsed power facility designed to achieve high yield fusion. The ignition and high gain targets proposed for use in the X1 utilize, in their interior, a spherical shell layer of solid cryogenic DT inside of a capsule. The target's DT layer must be cooled to below 19.7 K to solidify the DT. The thermal environment at the outer surface of the DT layer must be as uniform as the required DT layer uniformity. The heat generated in the DT by its radioactive beta decay and the cylindrical symmetry of the target's outer walls work against meeting these two requirements for producing a target with a DT layer acceptable for imploding. Thermal models were made using X1 target geometry. These show that high gain targets will likely be too hot to solidify the DT layer if the capsule cooling occurs solely via thermal conduction through the foam holding it in place inside of the target. A small amount of helium gas within the foam was shown to provide sufficient conductivity to allow solidification of the DT within the capsule. Too high a density of helium in the foam causes a strong thermal link between the cylindrical target walls and the capsule, which results in a non-uniform DT layer. Models were produced for which the DT layer uniformity and the temperature were acceptable over a reasonable range of helium density.

Alexander, N. B.

1998-11-01

58

Beam Model for Energetic Electron Transport in Laser Produced Plasmas  

NASA Astrophysics Data System (ADS)

Energetic electron transport,in laser target implosion codes, is generally handled with a phenominological flux limit . Other techniques include nonlocal transport algorithms (1), although issues have been raised about both their numerical stability and accuracy (2). We have explored a different approach, a beam deposition model. It reduces to Spitzer thermal conduction in the short mean free path limit, is intuitively reasonable, and with suitable approximations, can be economically incorporated into existing implicit numerical algorithms for the electron heat conduction. While our first formulation is for one dimensional plasmas, the model extends easily to two or three dinensions. Initial results appear to be reasonable, and will be presented. 1. Luciani et al, Phys. Rev. Let., 51, 1664, 1983 2.Prasad and Kershaw, Phys. Fluids. B 1, 2430, 1989, and B3, 3087, 1991

Manheimer, Wallace; Colombant, Denis

2002-11-01

59

Plasma processes for producing silanes and derivatives thereof  

DOEpatents

The invention is generally related to process for generating one or more molecules having the formula Si.sub.xH.sub.y, Si.sub.xD.sub.y, Si.sub.xH.sub.yD.sub.z, and mixtures thereof, where x,y and z are integers .gtoreq.1, H is hydrogen and D is deuterium, such as silane, comprising the steps of: providing a silicon containing material, wherein the silicon containing material includes at least 20 weight percent silicon atoms based on the total weight of the silicon containing material; generating a plasma capable of vaporizing a silicon atom, sputtering a silicon atom, or both using a plasma generating device; and contacting the plasma to the silicon containing material in a chamber having an atmosphere that includes at least about 0.5 mole percent hydrogen atoms and/or deuterium atoms based on the total moles of atoms in the atmosphere; so that a molecule having the formula Si.sub.xH.sub.y; (e.g., silane) is generated. The process preferably includes a step of removing one or more impurities from the Si.sub.xH.sub.y (e.g., the silane) to form a clean Si.sub.xH.sub.y, Si.sub.xD.sub.y, Si.sub.xH.sub.yD.sub.z (e.g., silane). The process may also include a step of reacting the Si.sub.xH.sub.y, Si.sub.xD.sub.y, Si.sub.xH.sub.yD.sub.z (e.g., the silane) to produce a high purity silicon containing material such as electronic grade metallic silicon, photovoltaic grade metallic silicon, or both.

Laine, Richard M; Massey, Dean Richard; Peterson, Peter Young

2014-03-25

60

[Testing of medicinal products produced from pooled plasma].  

PubMed

Medicinal products produced from human plasma fall under the administrative batch release procedure of the competent authority. In Germany, this has been carried out since 1995 by the Paul Ehrlich Institute (PEI), the responsible state control agency for blood products. Medicinal products released for the European and national market are tested for quality, efficacy and safety. Experimental testing of the final product and the starting materials, the plasma pools, as well as control of the production documentation guarantee a constantly high product safety. In the 28,000 batches tested since the beginning of the state controlled batch release testing of these blood products at the PEI, there has been no transmission of infectious viruses (HIV, HBV and HCV) to any patient. The batch release has made a contribution to the improvement of product quality. This procedure is still an important tool to ensure safety of blood products. The PEI is integrated in the batch release network of the European Directorate for the Quality of Medicines & Health Care (EDQM) in Strasbourg. Regulations and guidelines for official control authority batch release (OCABR) ensure harmonized procedures for mutual recognition of batch release on the European level. The EU certificates and German national certificates are requested and accepted in over 70 countries worldwide. Experimental testing in the EU and the requisite certificates have developed into a seal of quality for the world market. PMID:25213735

Unkelbach, U; Hunfeld, A; Breitner-Ruddock, S

2014-10-01

61

Enhancements of extreme ultraviolet emission using prepulsed Sn laser-produced plasmas for advanced lithography applications  

SciTech Connect

Laser-produced plasmas (LPP) from Sn targets are seriously considered to be the light source for extreme ultraviolet (EUV) next generation lithography, and optimization of such a source will lead to improved efficiency and reduced cost of ownership of the entire lithography system. We investigated the role of reheating a prepulsed plasma and its effect on EUV conversion efficiency (CE). A 6 ns, 1.06 {mu}m Nd:yttrium aluminum garnet laser was used to generate the initial plasma that was then reheated by a 40 ns, 10.6 {mu}m CO{sub 2} laser to generate enhanced EUV emission from a planar Sn target. The effects of prepulsed laser intensity and delay timings between the prepulsed and the pumping pulse were investigated to find the optimal pre-plasma conditions before the pumping pulse. The initial optimization of these parameters resulted in 25% increase in CE from the tin LPP. The cause of increased EUV emission was identified from EUV emission spectra and ion signal data.

Freeman, J. R.; Harilal, S. S.; Hassanein, A. [Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)

2011-10-15

62

Molten metal analysis by laser produced plasmas. Technical progress report  

SciTech Connect

A new method of molten metal analysis, based on time- and space-resolved spectroscopy of a laser-produced plasma (LPP) plume of a molten metal surface, has been implemented in the form of a prototype LPP sensor-probe, allowing in-situ analysis in less than 1 minute. The research at Lehigh University has been structured in 3 phases: laboratory verification of concept, comparison of LPP method with conventional analysis of solid specimens and field trials of prototype sensor-probe in small-scale metal shops, and design/production/installation of two sensor-probes in metal production shops. Accomplishments in the first 2 phases are reported. 6 tabs, 3 figs.

Kim, Yong W.

1994-02-01

63

Suprathermal electron transport in laser-produced plasmas  

SciTech Connect

A self-consistent, collisional, particle-in-cell scheme has been developed to model the one dimensional transport of suprathermal electrons in laser produced plasmas. This full Monte Carlo approach was taken, since earlier, simpler models have failed to explain an experimentally almost universal anomalous inhibition of thermal transport. The Monte Carlo scheme allows for free-streaming, ion scatter, and self thermalization of the electrons, which are moved in self-consistent E-fields computed with the aid of implicit fluid moments. PIC hydrodynamics for the ions, ponderomotive forces, and resonance and inverse-bremsstrahlung absorption of the light are all accommodated. In application to the anomalous inhibition problem, use of the scheme demonstrates that intrinsic differences in the Monte Carlo, and conventional flux-limited diffusion modelling of the transport results in apparent and real inhibition, explaining the need for strong flux-limiting in the simpler diffusion modelling of experiments.

Mason, R.J.

1981-01-01

64

Atmospheric plasma inactivation of foodborne pathogens on fresh produce surfaces.  

PubMed

A study was conducted to determine the effect of one atmosphere uniform glow discharge plasma (OAUGDP) on inactivation of Escherichia coli O157:H7, Salmonella, and Listeria monocytogenes on apples, cantaloupe, and lettuce, respectively. A five-strain mixture of cultured test organisms was washed, suspended in phosphate buffer, and spot inoculated onto produce (7 log CFU per sample). Samples were exposed inside a chamber affixed to the OAUGDP blower unit operated at a power of 9 kV and frequency of 6 kHz. This configuration allows the sample to be placed outside of the plasma generation unit while allowing airflow to carry the antimicrobial active species, including ozone and nitric oxide, onto the food sample. Cantaloupe and lettuce samples were exposed for 1, 3, and 5 min, while apple samples were exposed for 30 s, 1 min, and 2 min. After exposure, samples were pummeled in 0.1% peptone water-2% Tween 80, diluted, and plated in duplicate onto selective media and tryptic soy agar and incubated as follows: E. coli O157:H7 (modified eosin methylene blue) and Salmonella (xylose lysine tergitol-4) for 48 h at 37 degrees C, and L. monocytogenes (modified Oxford medium) at 48 h for 32 degrees C. E. coli O157:H7 populations were reduced by >1 log after 30-s and 1-min exposures and >2 log after a 2-min exposure. Salmonella populations were reduced by >2 log after 1 min. Three- and 5-min exposure times resulted in >3-log reduction. L. monocytogenes populations were reduced by 1 log after 1 min of exposure. Three- and 5-min exposure times resulted in >3- and >5-log reductions, respectively. This process has the capability of serving as a novel, nonthermal processing technology to be used for reducing microbial populations on produce surfaces. PMID:17969610

Critzer, Faith J; Kelly-Wintenberg, Kimberly; South, Suzanne L; Golden, David A

2007-10-01

65

Bragg Scattering of Electromagnetic Wave by Microwave Produced Periodic Plasma Layers  

NASA Astrophysics Data System (ADS)

The feasibility of using artificial atmospheric plasma as a Bragg reflector in the upper atmosphere to relay electromagnetic wave is studied. The research includes three parts, (1) the generation of periodic plasma layers and their reflectivity; (2) the lifetime of plasma electrons; and (3) the propagation of high power microwave pulse in air breakdown environment. A set of parallel plasma layers is generated by the intersecting high power microwave pulses in the center region of a Plexiglass chamber. A Bragg scattering experiment, using the plasma layers as a Bragg reflector is then performed. Both time domain and frequency domain measurements of wave scattering are conducted. The experiment results are found to agree very well with the theory. Moreover, the time domain measurement of wave scattering provides an unambiguous way for determining the temporal evolution of electron density during the first 100mus period. The results of measurement show that the electrons decay initially at the attachment rate. However, when enough negative molecule ions are produced through the electron attachment process, the regeneration of electrons via detachment process is increased and eventually balances out the electron attachment loss. The net electron loss is then determined by the recombination rate. The propagation of high power microwave pulses is studied experimentally. The mechanisms responsible for two different degree of tail erosion are identified. Using a forward wave approximation model, the propagation of a high power microwave pulse is also studied numerically. The numerical results are shown to agree very well with the experimental results.

Zhang, Yong-Shan

66

Detailed energy distributions in laser-produced plasmas of solid gold and foam gold planar targets  

SciTech Connect

Foam gold was proposed to increase the laser to x-ray conversion efficiency due to its important applications. To understand the mechanism of x-ray enhancement, the detailed energy distributions and plasma profiles for laser-irradiated solid gold and foam gold targets were studied comparatively by hydrodynamic simulations using the code Multi-1D. It is confirmed that the radiation heat wave is subsonic for the normal solid gold target, while supersonic for the foam gold target. The shock wave, which is behind the supersonic radiation heat wave for the foam gold target, generates a plasma temperature gradient with high temperature near the shock wave front to produce an additional net outward radiation for enhancement of the x-ray emission. Much larger inward plasma velocity is also driven by the shock wave as an initial plasma velocity for the laser deposition and electron thermal conduct zone, which decreases the expanding plasma kinetic energy loss and helps to increase the x-ray radiation.

Dong, Yunsong [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China) [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Zhang, Lu; Yang, Jiamin; Shang, Wanli [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China)] [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China)

2013-12-15

67

Focused excimer laser initiated, radio frequency sustained high pressure air plasmas  

NASA Astrophysics Data System (ADS)

Measurements and analysis of air breakdown processes and plasma production by focusing 193 nm, 300 mJ, 15 MW high power laser radiation inside a 6 cm diameter helical radio frequency (RF) coil are presented. Quantum resonant multi-photon ionization (REMPI) and collisional cascade laser ionization processes are exploited that have been shown to produce high-density (ne ˜ 7 × 1016/cm3) cylindrical seed plasmas at 760 Torr. Air breakdown in lower pressures (from 7-22 Torr), where REMPI is the dominant laser ionization process, is investigated using an UV 18 cm focal length lens, resulting in a laser flux of 5.5 GW/cm2 at the focal spot. The focused laser power absorption and associated shock wave produce seed plasmas for sustainment by the RF (5 kW incident power, 1.5 s) pulse. Measurements of the helical RF antenna load impedance in the inductive and capacitive coupling regimes are obtained by measuring the loaded antenna reflection coefficient. A 105 GHz interferometer is used to measure the plasma electron density and collision frequency. Spectroscopic measurements of the plasma and comparison with the SPECAIR code are made to determine translational, rotational, and vibrational neutral temperatures and the associated neutral gas temperature. From this and the associated measurement of the gas pressure the electron temperature is obtained. Experiments show that the laser-formed seed plasma allows RF sustainment at higher initial air pressures (up to 22 Torr) than that obtained via RF-only initiation (<18 Torr) by means of a 0.3 J UV laser pulse.

Giar, Ryan; Scharer, John

2011-11-01

68

Focused excimer laser initiated, radio frequency sustained high pressure air plasmas  

SciTech Connect

Measurements and analysis of air breakdown processes and plasma production by focusing 193 nm, 300 mJ, 15 MW high power laser radiation inside a 6 cm diameter helical radio frequency (RF) coil are presented. Quantum resonant multi-photon ionization (REMPI) and collisional cascade laser ionization processes are exploited that have been shown to produce high-density (n{sub e} {approx} 7 x 10{sup 16}/cm{sup 3}) cylindrical seed plasmas at 760 Torr. Air breakdown in lower pressures (from 7-22 Torr), where REMPI is the dominant laser ionization process, is investigated using an UV 18 cm focal length lens, resulting in a laser flux of 5.5 GW/cm{sup 2} at the focal spot. The focused laser power absorption and associated shock wave produce seed plasmas for sustainment by the RF (5 kW incident power, 1.5 s) pulse. Measurements of the helical RF antenna load impedance in the inductive and capacitive coupling regimes are obtained by measuring the loaded antenna reflection coefficient. A 105 GHz interferometer is used to measure the plasma electron density and collision frequency. Spectroscopic measurements of the plasma and comparison with the SPECAIR code are made to determine translational, rotational, and vibrational neutral temperatures and the associated neutral gas temperature. From this and the associated measurement of the gas pressure the electron temperature is obtained. Experiments show that the laser-formed seed plasma allows RF sustainment at higher initial air pressures (up to 22 Torr) than that obtained via RF-only initiation (<18 Torr) by means of a 0.3 J UV laser pulse.

Giar, Ryan; Scharer, John [Department of Electrical Engineering, University of Wisconsin-Madison, 506 Engineering Research Building, 1500 Engineering Drive, Madison, Wisconsin 53706 (United States)

2011-11-15

69

Focused excimer laser initiated and radio frequency sustained plasma formation in high pressure air  

NASA Astrophysics Data System (ADS)

A doctoral thesis project was performed to experimentally investigate the feasibility of focused excimer laser initiation of air plasmas for radio frequency sustainment. A 193 nm, 15 MW, 300 mJ laser was focused with a 18 cm focal length lens to form a small, high density (ne ~ 10 14 cm--3) seed plasma. These laser plasmas were produced inside a borosilicate glass tube around which was wrapped a 5 turn helical antenna. This antenna was powered with 5 kW of 13.56 MHz of radiation for 1.5 s. This was accomplished at a pressure of 22 Torr, resulting in a large volume (300 cm3) air plasma. Diagnostic measurements of this air plasma determined an electron density of 5E10 cm-3 and an electron temperature 1.3 eV with a neutral temperature of 3500 K. The collision frequency was measured to be 9E10 Hz which resulted in a plasma-loaded antenna resistance of 6 O with a voltage reflection coefficient of 0.7.

Giar, Ryan

70

Dynamics of quark-gluon plasma produced in heavy ion collisions  

NASA Astrophysics Data System (ADS)

In this talk, we report on our results about the computation of isotropization and thermalization times of the quark-gluon plasma produced in relativistic heavy ion collisions, as well as of the elliptic flow. Simulation of the evolving fireball is achieved by solving the relativistic Boltzmann equation for the parton distribution function tuned at a fixed shear viscosity to entropy density ratio ?/s. Our results show that the saturation in the initial spectrum reduces the efficiency in building-up the elliptic flow. Moreover both thermalization and isotropization times are quite small, approximately of 1 fm/c, if the system is in a strong coupling regime.

Ruggieri, M.; Scardina, F.; Plumari, S.; Greco, V.

2014-11-01

71

Visible spectral power emitted from a laser produced uranium plasma  

NASA Technical Reports Server (NTRS)

The development of plasma-core nuclear reactors for advanced terrestrial and space-power sources is researched. Experimental measurements of the intensity and the spectral distribution of radiation from a nonfissioning uranium plasma are reported.

Williams, M. D.; Jalufka, N. W.

1975-01-01

72

Pressure-driven, resistive magnetohydrodynamic interchange instabilities in laser-produced high-energy-density plasmas  

E-print Network

Recent experiments using proton backlighting of laser-foil interactions provide unique opportunities for studying magnetized plasma instabilities in laser-produced high-energy-density plasmas. Time-gated proton radiograph ...

Li, Chikang

73

Soft x-ray spectral measurements for temperature determination of laser produced aluminum plasmas  

SciTech Connect

Time and space resolved measurements were made on plasmas produced by the SPRITE laser focused on aluminum targets. The experimental spectra are compared to theory in order to determine a characteristic plasma temperature. 4 refs., 8 figs.

Mitchell, K.B.; Abdallah, J. Jr.; Peek, J.M.

1986-01-01

74

Initial Studies of Core and Edge Transport of NSTX Plasmas  

SciTech Connect

Rapidly developing diagnostic, operational, and analysis capability is enabling the first detailed local physics studies to begin in high-beta plasmas of the National Spherical Torus Experiment (NSTX). These studies are motivated in part by energy confinement times in neutral-beam-heated discharges that are favorable with respect to predictions from the ITER-89P scaling expression. Analysis of heat fluxes based on profile measurements with neutral-beam injection (NBI) suggest that the ion thermal transport may be exceptionally low, and that electron thermal transport is the dominant loss channel. This analysis motivates studies of possible sources of ion heating not presently accounted for by classical collisional processes. Gyrokinetic microstability studies indicate that long wavelength turbulence with k(subscript ''theta'') rho(subscript ''i'') {approx} 0.1-1 may be suppressed in these plasmas, while modes with k(subscript ''theta'') rho(subscript ''i'') {approx} 50 may be robust. High-harmonic fast-wave (HHFW) heating efficiently heats electrons on NSTX, and studies have begun using it to assess transport in the electron channel. Regarding edge transport, H-mode [high-confinement mode] transitions occur with either NBI or HHFW heating. The power required for low-confinement mode (L-mode) to H-mode transitions far exceeds that expected from empirical edge-localized-mode-free H-mode scaling laws derived from moderate aspect ratio devices. Finally, initial fluctuation measurements made with two techniques are permitting the first characterizations of edge turbulence.

E.J. Synakowski; M.G. Bell; R.E. Bell; C.E. Bush; C. Bourdelle; D. Darrow; W. Dorland; A. Ejiri; E.D. Fredrickson; D.A. Gates; S.M. Kaye; S. Kubota; H.W. Kugel; B.P. LeBlanc; R. Maingi; R.J. Maqueda; J.E. Menard; D. Mueller; A. Rosenberg; S.A. Sabbagh; D. Stutman; G. Taylor; D.W. Johnson; R. Kaita; M. Ono; F. Paoletti; W. Peebles; Y-K.M. Peng; A.L. Roquemore (a), C.H. Skinner; V.A. Soukhanovskii; and the NSTX Research Team

2001-09-19

75

Studies on the propagation of relativistic plasma waves in high density plasmas produced by hypersonic ionizing shock waves  

Microsoft Academic Search

Summary form only given. The feasibility of using an ionizing shock wave to produce high-density plasmas suitable for the propagation of large-amplitude relativistic plasma waves is being investigated. A 20-kV arc-driven shock tube of coaxial geometry produces a hypersonic shock wave (10 < Mach < 60) in argon gas, which leaves in its wake a high-density plasma (np > 1017

R. L. Williams

1993-01-01

76

Metallic nanocluster formation in neutral gas-confined laser produced plasma afterglow  

SciTech Connect

Dense atom vapors are created as remnants of a three-dimensional (3D) laser-produced plasma (LPP) plume driven from a solid aluminum target by a gigawatt-class Nd:glass laser pulse. Formation of nanoclusters as the terminal state of aluminum vapors has been investigated. By plasma structure diagnosis, we have fully characterized the LPP plume in 3D as a function of time and from its evolution modeled its cooling to the critical point in more than 110 000 vapor cells. Clustering of atoms is calculated by numerical simulation of interparticle collisions. When the cluster size histogram is rescaled relative to the maximum population and the maximal radius, the rescaled histograms all collapse into a single functional form regardless of the time or the initial atom vapor density. The cluster size distribution for the entire plasma plume is obtained by summing over all plasma cells. Independently, the clusters are captured onto electron microscope grids and size analyzed by means of transmission electron microscopy. The computed result is in excellent agreement with the measured histograms of clusters by size.

Kim, Yong W.; Lee, Hedok; Belony, Paul Jr. [Department of Physics, Lehigh University, Bethlehem, Pennsylvania 18015 (United States)

2006-10-15

77

Characterization of linear plasma synthetic jet actuators in an initially quiescent medium  

SciTech Connect

The plasma synthetic jet actuator (PSJA) is a geometrical variant of the aerodynamic plasma actuator that can be used to produce zero-mass flux jets similar to those created by mechanical devices. This jet can be either three-dimensional using annular electrode arrays (annular PSJA) or nearly two dimensional using two rectangular-strip exposed electrodes and one embedded electrode (linear PSJA). Unsteady pulsing of the PSJA at time scales decoupled to the ac input frequency results in a flow field dominated by counter-rotating vortical structures similar to conventional synthetic jets, and the peak velocity and momentum of the jet is found to be affected by a combination of the pulsing frequency and input power. This paper investigates the fluid dynamic characteristics of linear plasma synthetic jet actuators in an initially quiescent medium. Two-dimensional particle image velocimetry measurements on the actuator are used to validate a previously developed numerical model wherein the plasma behavior is introduced into the Navier-Stokes equations as an electrohydrodynamic force term calculated from Maxwell's equations and solved for the fluid momentum. The numerical model was implemented in an incompressible, unstructured grid code. The results of the simulations are observed to reproduce some aspects of the qualitative and quantitative experimental behavior of the jet for steady and pulsed modes of actuator operation. The self-similarity behavior of plasma synthetic jets are examined and compared to mechanically driven continuous and synthetic jets.

Santhanakrishnan, Arvind [Department of Mathematics, Phillips Hall, CB 3250, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599-3250 (United States); Reasor, Daniel A. Jr. [School of Mechanical Engineering, Georgia Institute of Technology, Atlanta, Georgia 30332 (United States); LeBeau, Raymond P. Jr. [Department of Mechanical Engineering, University of Kentucky, Lexington, Kentucky 40506 (United States)

2009-04-15

78

Initial study of the optical spectrum of the ISIS H{sup -} ion source plasma  

SciTech Connect

The front end test stand is being constructed at the Rutherford Appleton Laboratory, with the aim of producing a 60 mA, 2 ms, 50 Hz, perfectly chopped H{sup -} ion beam. To meet the beam requirements, a more detailed understanding of the ion source plasma is required. To this end, an initial study is made of the optical spectrum of the plasma using a digital spectrometer. The atomic and molecular emission lines of hydrogen and caesium are clearly distinguished and a quantitative comparison is made when the ion source is run in different conditions. The electron temperature is 0.6 eV and measured line widths vary by up to 75%.

Lawrie, S. R.; Faircloth, D. C. [ISIS Pulsed Neutron and Muon Source, Rutherford Appleton Laboratory, Oxfordshire, OX11 0QX (United Kingdom); Philippe, K. [Institut Universitaire de Technologie Paris Jussieu, University of Paris Diderot, 75205 Paris Cedex 13 (France)

2012-02-15

79

Initial study of the optical spectrum of the ISIS H- ion source plasma.  

PubMed

The front end test stand is being constructed at the Rutherford Appleton Laboratory, with the aim of producing a 60 mA, 2 ms, 50 Hz, perfectly chopped H(-) ion beam. To meet the beam requirements, a more detailed understanding of the ion source plasma is required. To this end, an initial study is made of the optical spectrum of the plasma using a digital spectrometer. The atomic and molecular emission lines of hydrogen and caesium are clearly distinguished and a quantitative comparison is made when the ion source is run in different conditions. The electron temperature is 0.6 eV and measured line widths vary by up to 75%. PMID:22380213

Lawrie, S R; Faircloth, D C; Philippe, K

2012-02-01

80

ccsd00001731, Study on high pressure plasma produced by ArF  

E-print Network

ccsd­00001731, version 2 ­ 7 Nov 2004 Study on high pressure plasma produced by ArF laser Norio side window of chamber. The high pressure ArF laser plasma develops symmetrically and the plasma energy of ArF laser light is higher than the XeCl laser. The transmittance of ArF laser light

81

Plasma produced by impacts of fast dust particles on a thin film  

NASA Technical Reports Server (NTRS)

The thin-film impact plasma detector was pioneered by Berg for detecting small cosmic dust particles and measuring their approximate velocities in a time-of-flight configuration. While Berg's device was highly successful in establishing the flux of interplanetary dust, the accuracy of measuring the velocities of individual particles was a moderate 18 percent in magnitude and 27 degrees in angle. A much greater accuracy of less than or equal to 1 percent in determining the velocity components appears desirable in order to associate a particle with its parent body. In order to meet that need, research was initiated to determine if a thin-film detector can be designed to provide such accurate velocity measurements. Previous laboratory investigations of the impact plasma uncovered two difficulties: (1) solid or liquid spray is ejected from a primary impact crater and strikes neighboring walls where it produces secondary impact craters and plasma clouds; as a result, both quantity and time of detection of the plasma can vary significantly with the experiment configuration. Particles from an accelerator rarely have speeds v greater than or equal to 10-15 km/s, while cosmic dust particles typically impact at v = 10-72 km/s. The purpose of the tests discussed in this paper was to resolve the two difficulties mentioned. That is, the experiment configuration was designed to reduce the contribution of plasma from secondary impacts. In addition, most particles with v less than or equal to 25 km/s and all particles with v less than or equal to 10 km/s were eliminated from the beam.

Auer, Siegfried

1994-01-01

82

Jupiter plasma wave observations: an initial Voyager 1 overview  

Microsoft Academic Search

The Voyager 1 plasma wave instrument detected low-frequency radio emissions, ion acoustic waves, and electron plasma oscillations for a period of months before encountering Jupiter's bow shock. In the outer magnetosphere, measurements of trapped radio waves were used to derive an electron density profile. Near and within the Io plasma torus the instrument detected high-frequency electrostatic waves, strong whistler mode

F. L. Scarf; D. A. Gurnett; W. S. Kurth

1979-01-01

83

Research on plasma-puff initiation of high Coulomb transfer switches  

NASA Technical Reports Server (NTRS)

The plasma-puff triggering mechanism based on hypocycloidal pinch geometry was investigated to determine the optimal operating conditions for an azimuthally uniform surface flashover which initiates plasma-puff under wide ranges of fill gas pressures of Ar, He and N2. Research is presented and resulting conference papers are attached. These papers include 'Characteristics of Plasma-Puff Trigger for an Inverse-Pinch Plasma Switch'; 'Ultra-High-Power Plasma Switch INPUTS for Pulse Power Systems'; 'Characteristics of Switching Plasma in an Inverse-Pinch Switch'; 'Comparative Study of INPIStron and Spark Gap'; and 'INPIStron Switched Pulsed Power for Dense Plasma Pinches.'

Venable, Demetrius D.; Han, Kwang S.

1993-01-01

84

Theoretical and Experimental Databases for High Average Power EUV Light Source by Laser Produced Plasma  

Microsoft Academic Search

Extreme ultraviolet (EUV) radiation from laser-produced plasma has been thoroughly studied for application in mass-production of the next generation semiconductor devices. Comprehensive experimental databases are provided for a wide range of parameters of lasers and targets. The atomic models are benchmarked with spectroscopic measurements not only for laser-produced plasma (LPP) but also for EUV emissions from magnetic-confinement plasmas or the

H. Nishimura; K. Nishihara; S. Fujioka; T. Aota; T. Ando; M. Shimomura; K. Sakaguchi; Y. Simada; M. Yamaura; K. Nagai; T. Norimatsu; A. Sunahara; M. Murakami; A. Sasaki; H. Tanuma; F. Koike; K. Fuijma; C. Suzuki; S. Morita; T. Kato; T. Kagawa; T. Nishikawa; N. Miyanaga; Y. Izawa; K. Mima

2007-01-01

85

Plasma Choline Metabolites and Colorectal Cancer Risk in the Women's Health Initiative Observational Study.  

PubMed

Few studies have examined associations between plasma choline metabolites and risk of colorectal cancer. Therefore, we investigated associations between plasma biomarkers of choline metabolism [choline, betaine, dimethylglycine, and trimethylamine N-oxide (TMAO)] and colorectal cancer risk among postmenopausal women in a case-control study nested within the Women's Health Initiative Observational Study. We selected 835 matched case-control pairs, and cases were further stratified by tumor site (proximal, distal, or rectal) and stage (local/regional or metastatic). Colorectal cancer was assessed by self-report and confirmed by medical records over the mean of 5.2 years of follow-up. Baseline plasma choline metabolites were measured by LC/MS-MS. In multivariable-adjusted conditional logistic regression models, plasma choline tended to be positively associated with rectal cancer risk [OR (95% confidence interval, CI)highest vs. lowest quartile = 2.44 (0.93-6.40); P trend = 0.08], whereas plasma betaine was inversely associated with colorectal cancer overall [0.68 (0.47-0.99); P trend = 0.01] and with local/regional tumors [0.64 (0.42-0.99); P trend = 0.009]. Notably, the plasma betaine:choline ratio was inversely associated with colorectal cancer overall [0.56 (0.39-0.82); P trend = 0.004] as well as with proximal [0.66 (0.41-1.06); P trend = 0.049], rectal [0.27 (0.10-0.78); P trend = 0.02], and local/regional [0.50 (0.33-0.76); P trend = 0.001] tumors. Finally, plasma TMAO, an oxidative derivative of choline produced by intestinal bacteria, was positively associated with rectal cancer [3.38 (1.25-9.16); P trend = 0.02] and with overall colorectal cancer risk among women with lower (vs. higher) plasma vitamin B12 levels (P interaction = 0.003). Collectively, these data suggest that alterations in choline metabolism, which may arise early in disease development, may be associated with higher risk of colorectal cancer. The positive association between plasma TMAO and colorectal cancer risk is consistent with an involvement of the gut microbiome in colorectal cancer pathogenesis. Cancer Res; 74(24); 7442-52. ©2014 AACR. PMID:25336191

Bae, Sajin; Ulrich, Cornelia M; Neuhouser, Marian L; Malysheva, Olga; Bailey, Lynn B; Xiao, Liren; Brown, Elissa C; Cushing-Haugen, Kara L; Zheng, Yingye; Cheng, Ting-Yuan David; Miller, Joshua W; Green, Ralph; Lane, Dorothy S; Beresford, Shirley A A; Caudill, Marie A

2014-12-15

86

Energy loss of heavy ions in laser-produced plasmas  

NASA Astrophysics Data System (ADS)

The unique combination of a high-energy Nd:glass laser system and the intense heavy-ion beam at Gesellschaft für Schwerionenforschung (GSI) allowed for the first time the measurement of the stopping power of heavy ions in plasmas at the level of one percent solid-state density and temperatures of about 60 eV. Energy loss measurements of swift heavy ions (5 6 MeV/u) in a carbon plasma revealed a stopping power exceeding theoretical predictions which was not observed in earlier experiments at lower plasma densities. This discrepancy can be resolved assuming higher effective charge states of the projectiles resulting in a consistent picture for the measured parameter range.

Roth, M.; Stöckl, C.; Süß, W.; Iwase, O.; Gericke, D. O.; Bock, R.; Hoffmann, D. H. H.; Geissel, M.; Seelig, W.

2000-04-01

87

Diamond-like carbon sputtering by laser produced Xe plasma  

NASA Astrophysics Data System (ADS)

The sputtering of diamond-like carbon (DLC) was investigated using Xe ion bombardment from the laser plasma X-ray source (LPX). The LPX we developed uses a solid Xe target and emits UV-X-rays and Xe ions. Using the LPX as an ion source, we measured etching depths of DLC, Ru, and Au films using a quartz crystal microbalance (QCM) to determine their ion sputtering rates at incident angles of 0° and 70°. The calculated results by the SRIM code were able to predict the measured results, except for the case of the DLC film at 0° incident. Our measured result indicated that the DLC sputtering at 0° was ten times larger than previously reported data, in which an ion gun was used. We consider that the difference was a characteristic effect of the laser plasma, and can be explained as a synergistic effect of ion bombardment and UV radiation from the Xe plasma.

Amano, Sho; Inoue, Tomoaki

2013-11-01

88

Multilayer refractory nozzles produced by plasma-spray process  

NASA Technical Reports Server (NTRS)

Multilayer rocket nozzles formed by plasma spraying have good thermal shock resistance and can be reheated in an oxidizing environment without loss of coating adherence. Suggested application of this process are for the production of refractory components, which can be formed as surfaces of revolution.

Bliton, J. L.; Rausch, J. L.

1966-01-01

89

Characterisation of plasmas produced by the “Torche a Injection Axiale”  

Microsoft Academic Search

Summary form only given. The Torche a Injection Axiale (TIA), i.e. torch with axial gas injection, was developed by the group of Moisan in 1993. We report on the investigations on two different kind of plasmas created by the TIA: one with helium and the other with argon as main gas. Using absolute line intensity measurements the densities of the

J. Jonkers; L. J. M. Selen; Mullen van der JJAM; J. M. De Regt; E. A. H. Timmermans; D. C. Schram

1996-01-01

90

Plasma observations near Saturn - Initial results from Voyager 1  

Microsoft Academic Search

The Voyager 1 encounter with Saturn and its satellites yielded extensive measurements of magnetospheric low-energy plasma electrons and positive ions, both heavy and light, probably of hydrogen and nitrogen or oxygen. At radial distances between 15 and 7 Saturn radii on the inbound trajectory, the plasma appears to corotate with a velocity within 20% of that theoretically expected for rigid

H. S. Bridge; J. W. Belcher; A. J. Lazarus; S. Olbert; J. D. Sullivan; F. Bagenal; P. R. Gazis; R. E. Hartle; K. W. Ogilvie; J. D. Scudder; E. C. Sittler; A. Eviatar; G. L. Siscoe; C. K. Goertz; V. M. Vasyliunas

1981-01-01

91

Plasma observations near Neptune - Initial results from Voyager 2  

Microsoft Academic Search

The plasma science experiment on Voyager 2 made observations of the plasma environment in Neptune's magnetosphere and in the surrounding solar wind. Because of the large tilt of the magnetic dipole and fortuitous timing, Voyager entered Neptune's magnetosphere through the cusp region, the first cusp observations at an outer planet. Thus the transition from the magnetosheath to the magnetosphere observed

J. W. Belcher; H. S. Bridge; B. Coppi; G. S. Gordon Jr.; A. J. Lazarus; R. L. McNutt Jr.; F. Bagenal; O. Divers; A. Eviatar; K. W. Ogilvie; L. Villanueva; M. Zhang; E. C. Jr. Sittler; G. L. Siscoe; V. M. Vasyliunas

1989-01-01

92

Robe Development for Electrical Conductivity Analysis in an Electron Gun Produced Helium Plasma  

NASA Technical Reports Server (NTRS)

The use of magnetohydrodynamic (MHD) power conversion systems, potentially coupled with a fission power source, is currently being investigated as a driver for an advanced propulsion system, such as a plasma thruster. The efficiency of a MHD generator is strongly dependent on the electrical conductivity of the fluid that passes through the generator; power density increases as fluid conductivity increases. Although traditional MHD flows depend on thermal ionization to enhance the electrical conductivity, ionization due to nuclear interactions may achieve a comparable or improved conductivity enhancement while avoiding many of the limitations inherent to thermal ionization. Calculations suggest that nuclear-enhanced electrical conductivity increases as the neutron flux increases; conductivity of pure He-3 greater than 10 mho/m may be achievable if exposed to a flux greater than 10(exp 12) neutrons/cm2/s.) However, this remains to be demonstrated experimentally. An experimental facility has been constructed at the Propulsion Research Center at the NASA Marshall Space Flight Center, using helium as the test fluid. High energy electrons will be used to simulate the effects of neutron-induced ionization of helium gas to produce a plasma. These experiments will be focused on diagnosis of the plasma in a virtually static system; results will be applied to future tests with a MHD system. Initial experiments will utilize a 50 keV electron gun that can operate at up to a current of 200 micro A. Spreading the electron beam over a four inch diameter window results in an electron flux of 1.5x 10(exp 13) e/sq cm/s. The equivalent neutron flux that would produce the same ionization fraction in helium is 1x10(exp 12) n/sq cm/s. Experiments will simulate the neutron generated plasma modeled by Bitteker, which takes into account the products of thermal neutron absorption in He-3, and includes various ion species in estimating the conductivity of the resulting plasma. Several different probes will be designed and implemented to verify the plasma kinetics model. System parameters and estimated operating ranges are summarized. The predicted ionization fraction, electron density, and conductivity levels are provided in for an equivalent neutron flux of 1x10(exp 12) n/cm2/s. Understanding the complex plasma kinetics throughout a MHD channel is necessary to design an optimal power conversion system for space propulsion applications. The proposed experiments seek to fully characterize the helium plasma and to determine the reliability of each measurement technique, such that they may be applied to more advanced MHD studies. The expected value of each plasma parameter determined from theoretical models will be verified experimentally by several independent techniques to determine the most reliable method of obtaining each parameter. The results of these experiments will be presented in the final paper.

Bragg-Sitton, Shannon M.; Bitteker, Leo; Rodgers, Stephen L. (Technical Monitor)

2002-01-01

93

INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Composition and dynamics of an erosion plasma produced by microsecond laser pulses  

NASA Astrophysics Data System (ADS)

The ion and energy compositions were determined and the dynamics was studied of an erosion plume formed by microsecond CO2 laser pulses incident on a graphite target. The ionic emission lines were used to find the electron density and temperature of the plasma on the target surface. The temperature of the plasma source did not change throughout the line emission time (4 ?s). At the plasma recombination stage the lines of the C II, C III, and C IV ions were accompanied by bands of the C2 molecule near the target surface and also near the surface of an substrate when a plasma flow interacted with it. Ways were found for controlling the plume expansion anisotropy and for producing plasma flows with controlled parameters by selection of the conditions during formation of a quasisteady erosion plasma flow.

Anisimov, V. N.; Grishina, V. G.; Derkach, O. N.; Sebrant, A. Yu; Stepanova, M. A.

1995-08-01

94

Features of plasma produced by excimer laser at low intensities  

Microsoft Academic Search

A plasma, created at interaction of short-wavelength excimer laser radiation with flat targets was investigated (tlas = 12 ns, lambdalas = 0.308 mum, qlas = 4 - 8 × 1012 W\\/cm2) with the help of various x-ray spectroscopic methods. The comparison of shapes and intensities of some observable spectral lines of H-, He and Li-like ions of Na, Mg and

G. A. Vergunova; A. I. Magunov; V. M. Dyakin; A. Ya Faenov; T. A. Pikuz; I. Yu Skobelev; D. Batani; S. Bossi; A. Bernardinello; F. Flora; P. di Lazzaro; S. Bollanti; N. Lisi; T. Letardi; A. Reale; L. Palladino; A. Scafati; L. Reale; A. L. Osterheld; W. H. Goldstein

1997-01-01

95

Topical applications of resonance internal conversion in laser produced plasma  

NASA Astrophysics Data System (ADS)

Physical aspects of resonance effects arising in plasma due to interactions of nuclei with the electrons are considered. Among them are resonance conversion (TEEN) and the reverse process of NEET. These processes are of great importance for pumping the excited nuclear states (isomers) and for accelerating their decay. Experiment is discussed on studying the unique 3.5-eV 229m Th nuclide.

Karpeshin, F. F.

2007-04-01

96

Astrophysical Weibel instability in counterstreaming laser-produced plasmas  

NASA Astrophysics Data System (ADS)

Astrophysical shock waves play diverse roles, including energizing cosmic rays in the blast waves of astrophysical explosions, and generating primordial magnetic fields during the formation of galaxies and clusters. These shocks are typically collisionless and require collective electromagnetic fields to couple the upstream and downstream plasmas. The Weibel instability has been proposed to provide the requisite interaction mechanism for shock formation in weakly-magnetized shocks by generating turbulent electric and magnetic fields in the shock front. This work presents the first laboratory identification of this Weibel instability between counterstreaming supersonic plasma flows and confirms its basic features, a significant step towards understanding these shocks. In the experiments, conducted on the OMEGA EP laser facility at the University of Rochester, a pair of plasmas plumes are generated by irradiating of a pair of opposing parallel plastic (CH) targets. The ion-ion interaction between the two plumes is collisionless, so as the plumes interpenetrate, supersonic, counterstreaming ion flow conditions are obtained. Electromagnetic fields formed in the interaction of the two plumes were probed with an ultrafast laser-driven proton beam, and we observed the growth of a highly striated, transverse instability with extended filaments parallel to the flows. The instability is identified as an ion-driven Weibel instability through agreement with analytic theory and particle-in-cell simulations, paving the way for further detailed laboratory study of this instability and its consequences for particle energization and shock formation.[1] W. Fox, G. Fiksel, A. Bhattacharjee, P. Y. Chang, K. Germaschewski, S. X. Hu, and P. M. Nilson, “Filamentation instability of counterstreaming laser-driven plasmas,” Phys. Rev. Lett. 111, 225002 (2013).

Fox, William; Fiksel, Gennady; Bhattacharjee, Amitava; Change, Po-Yu; Germaschewski, Kai; Hu, Suxing; Nilson, Philip

2014-06-01

97

Feasibility of measuring density and temperature of laser produced plasmas using spectroscopic techniques.  

SciTech Connect

A wide variety of experiments on the Z-Beamlet laser involve the creation of laser produced plasmas. Having a direct measurement of the density and temperature of these plasma would an extremely useful tool, as understanding how these quantities evolve in space and time gives insight into the causes of changes in other physical processes, such as x-ray generation and opacity. We propose to investigate the possibility of diagnosing the density and temperature of laser-produced plasma using temporally and spatially resolved spectroscopic techniques that are similar to ones that have been successfully fielded on other systems. Various researchers have measured the density and temperature of laboratory plasmas by looking at the width and intensity ratio of various characteristic lines in gases such as nitrogen and hydrogen, as well as in plasmas produced off of solid targets such as zinc. The plasma conditions produce two major measurable effects on the characteristic spectral lines of that plasma. The 1st is the Stark broadening of an individual line, which depends on the electron density of the plasma, with higher densities leading to broader lines. The second effect is a change in the ratio of various lines in the plasma corresponding to different ionization states. By looking at the ratio of these lines, we can gain some understanding of the plasma ionization state and consequently its temperature (and ion density when coupled with the broadening measurement). The hotter a plasma is, the higher greater the intensity of lines corresponding to higher ionization states. We would like to investigate fielding a system on the Z-Beamlet laser chamber to spectroscopically study laser produced plasmas from different material targets.

Edens, Aaron D.

2008-09-01

98

Plasma observations near Saturn - Initial results from Voyager 1  

NASA Technical Reports Server (NTRS)

The Voyager 1 encounter with Saturn and its satellites yielded extensive measurements of magnetospheric low-energy plasma electrons and positive ions, both heavy and light, probably of hydrogen and nitrogen or oxygen. At radial distances between 15 and 7 Saturn radii on the inbound trajectory, the plasma appears to corotate with a velocity within 20% of that theoretically expected for rigid corotation. The Titan data, taken while the moon was inside the Saturn magnetosphere, shows a clear signature characteristic of the interaction between a subsonic corotating magnetospheric plasma and the atmospheric or ionospheric exosphere of Titan.

Bridge, H. S.; Belcher, J. W.; Lazarus, A. J.; Olbert, S.; Sullivan, J. D.; Bagenal, F.; Gazis, P. R.; Hartle, R. E.; Ogilvie, K. W.; Scudder, J. D.

1981-01-01

99

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

SciTech Connect

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

Kitazaki, Satoshi; Hayashi, Nobuya [Faculty of Science and Engineering, Saga University, 1 Honjo-machi, Saga-shi, Saga, 840-8502 (Japan); Goto, Masaaki [Faculty of Medicine, Saga University, 5-1-1 Nabeshima, Saga-shi, Saga, 849-8501 (Japan)

2010-10-13

100

The model of plasma-electronic technology of producing electricity from electron beams  

NASA Astrophysics Data System (ADS)

The article obtains the main results of the research on plasma- electronic technology for producing electricity from electronic beams, based on the electrical properties of electrons and their combination in the form of electron beams. The functional diagram of the experimental setup implementing plasma-electronic technology that proves the possibility of electricity generation by electrical installations, based on plasma-electronic technology is described.

Ryzhov, D. R.; Kazmin, B. N.; Trifanov, I. V.

2015-01-01

101

Ion beam and plasma methods of producing diamondlike carbon films  

NASA Technical Reports Server (NTRS)

A variety of plasma and ion beam techniques was employed to generate diamondlike carbon films. These methods included the use of RF sputtering, dc glow discharge, vacuum arc, plasma gun, ion beam sputtering, and both single and dual ion beam deposition. Since films were generated using a wide variety of techniques, the physico-chemical properties of these films varied considerably. In general, these films had characteristics that were desirable in a number of applications. For example, the films generated using both single and dual ion beam systems were evaluated for applications including power electronics as insulated gates and protective coatings on transmitting windows. These films were impervious to reagents which dissolve graphitic and polymeric carbon structures. Nuclear reaction and combustion analysis indicated hydrogen to carbon ratios to be 1.00, which allowed the films to have good transmittance not only in the infrared, but also in the visible. Other evaluated properties of these films include band gap, resistivity, adherence, density, microhardness, and intrinsic stress. The results of these studies and those of the other techniques for depositing diamondlike carbon films are presented.

Swec, Diane M.; Mirtich, Michael J.; Banks, Bruce A.

1988-01-01

102

Activation of K+ Channels in the Plasma Membrane of Arabidopsis by ATP Produced Photosynthetically  

Microsoft Academic Search

Light activates a K+ channel and transiently depolarizes the plasma membrane of Arabidopsis mesophyll cells. Geneti- cally or chemically impairing photosynthesis abolished this electrical response to light. These results indicate that illuminated chloroplasts produce a factor that activated K+ channels in the plasma membrane. By patch clamping at the single-channel levei, we have obtained evidence that ATP is one such

Edgar P. Spalding; Mary Helen; M. Goldsmith

1993-01-01

103

System to continuously produce carbon fiber via microwave assisted plasma processing  

Microsoft Academic Search

A system to continuously produce fully carbonized or graphitized carbon fibers using microwave-assisted plasma (MAP) processing comprises an elongated chamber in which a microwave plasma is excited in a selected gas atmosphere. Fiber is drawn continuously through the chamber, entering and exiting through openings designed to minimize in-leakage of air. There is a gradient of microwave power within the chamber

Terry L. White; Felix L. Paulauskas; Timothy S. Bigelow

2010-01-01

104

Spatio-temporal mapping of ablated species in ultrafast laser-produced graphite plasmas  

E-print Network

Spatio-temporal mapping of ablated species in ultrafast laser-produced graphite plasmas K. F. Al pressures. Plasmas were generated by irradiating planar graphite targets using 40 fs pulses of 800 nm species popu- lations, emission, and kinetics. In recent years, graphite based nanomaterials (graphene

Harilal, S. S.

105

On the atomic state densities of plasmas produced by the “torche à injection axiale”  

Microsoft Academic Search

The atomic state densities of helium and argon plasmas produced by the microwave driven plasma torch called the “torche à injection axiale” are presented. They are obtained by absolute line intensity measurements of the excited states and by applying the ideal gas law to the ground state. It will be shown that the atomic state distribution function (ASDF) does not

J. Jonkers; H. P. C. Vos; Mullen van der JJAM; E. A. H. Timmermans

1996-01-01

106

Ballistic pendula for measuring the momentum of a laser-produced plasma  

SciTech Connect

We describe the use of a ballistic pendulum array to measure the momentum of a laser-produced plasma. An insitu calibration method is described and the pendulum results are compared to measurements made with other diagnostics.

Grun, J.; Ripin, B.H.

1982-09-17

107

Ballistic pendula for measuring the momentum of a laser-produced plasma  

SciTech Connect

We describe the use of a ballistic pendulum array to measure the momentum of a laser-produced plasma. An in situ calibration method is described and the pendulum results are compared to measurements made with other diagnostics.

Grun, J.; Ripin, B.H.

1982-12-01

108

Soft x-ray amplification in laser-produced recombination plasma  

NASA Astrophysics Data System (ADS)

We made a 2-D simulation of a laser-produced recombination plasma on a magnesium gutter target for the purpose of moderating a steep density gradient produced in the freely expanding plasma. As a result, it was found that a spatially uniform density region is formed in the neighborhood of the wall of the gutter, still providing a comparatively high gain for the Balmer-? transition in hydrogenic ions.

Takakuwa, H.; Kobayashi, Y.; Nozawa, O.; Shimizu, K.; Go, K.; Kitazawa, H.; Karashima, S.

1996-05-01

109

Initial elementary processes in tetrafluoroethylene plasma: An ab initio molecular orbital study  

NASA Astrophysics Data System (ADS)

Initial elementary processes in tetrafluoroethylene plasma are studied by using an ab initio molecular orbital method. The energy-surfaces at excited states are obtained by the Hartree-Fock method with a double zeta basis set, plus Rydberg orbitals. A ?-?* transition is low-lying both at singlet and triplet excited states. Vinyl-polymerization-type reactions are expected in the presence of some radical species via these transitions. The C=C bond cleaves via a triplet ?-?* transition to form CF2. The predicted elementary processes via these states are compatible with experimental results that C2F4* and CF2 are primary precursors. No excited states that bring about a C—F bond cleavage are obtained within 10 eV of the ground state. As a path for a C—F bond cleavage, a dissociative electron attachment process is found in a low energy region. This process is considered to be important for producing fluorine anions.

Sato, Kota; Komatsu, Toru; Iwabuchi, Susumu

1993-12-01

110

Plasma observations near saturn: initial results from voyager 1.  

PubMed

Extensive measurements of low-energy plasma electrons and positive ions were made during the Voyager 1 encounter with Saturn and its satellites. The magnetospheric plasma contains light and heavy ions, probably hydrogen and nitrogen or oxygen; at radial distances between 15 and 7 Saturn-radii (Rs) on the inbound trajectory, the plasma appears to corotate with a velocity within 20 percent of that expected for rigid corotation. The general morphology of Saturn's magnetosphere is well represented by a plasma sheet that extends from at least 5 to 17 Rs, is symmetrical with respect to Saturn's equatorial plane and rotation axis, and appears to be well ordered by the magnetic shell parameter L (which represents the equatorial distance of a magnetic field line measured in units of Rs). Within this general configuration, two distinct structures can be identified: a central plasma sheet observed from L = 5 to L = 8 in which the density decreases rapidly away from the equatorial plane, and a more extended structure from L = 7 to beyond 18 Rs in which the density profile is nearly flat for a distance +/- 1.8 Rs off the plane and falls rapidly thereafter. The encounter with Titan took place inside the magnetosphere. The data show a clear signature characteristic of the interaction between a subsonic corotating magnetospheric plasma and the atmospheric or ionospheric exosphere of Titan. Titan appears to be a significant source of ions for the outer magnetosphere. The locations of bow shock crossings observed inbound and outbound indicate that the shape of the Saturnian magnetosphere is similar to that of Earth and that the position of the stagnation point scales approximately as the inverse one-sixth power of the ram pressure. PMID:17783833

Bridge, H S; Belcher, J W; Lazarus, A J; Olbert, S; Sullivan, J D; Bagenal, F; Gazis, P R; Hartle, R E; Ogilvie, K W; Scudder, J D; Sittler, E C; Eviatar, A; Siscoe, G L; Goertz, C K; Vasyliunas, V M

1981-04-10

111

Emittance of positron beams produced in intense laser plasma interaction  

NASA Astrophysics Data System (ADS)

The first measurement of the emittance of intense laser-produced positron beams has been made. The emittance values were derived through measurements of positron beam divergence and source size for different peak positron energies under various laser conditions. For one of these laser conditions, we used a one dimensional pepper-pot technique to refine the emittance value. The laser-produced positrons have a geometric emittance between 100 and 500 mm.mrad, comparable to the positron sources used at existing accelerators. With 1010-1012 positrons per bunch, this low emittance beam, which is quasi-monoenergetic in the energy range of 5-20 MeV, may be useful as an alternative positron source for future accelerators.

Chen, Hui; Sheppard, J. C.; Meyerhofer, D. D.; Hazi, A.; Link, A.; Anderson, S.; Baldis, H. A.; Fedosejev, R.; Gronberg, J.; Izumi, N.; Kerr, S.; Marley, E.; Park, J.; Tommasini, R.; Wilks, S.; Williams, G. J.

2013-01-01

112

Emittance of positron beams produced in intense laser plasma interaction  

SciTech Connect

The first measurement of the emittance of intense laser-produced positron beams has been made. The emittance values were derived through measurements of positron beam divergence and source size for different peak positron energies under various laser conditions. For one of these laser conditions, we used a one dimensional pepper-pot technique to refine the emittance value. The laser-produced positrons have a geometric emittance between 100 and 500 mm{center_dot}mrad, comparable to the positron sources used at existing accelerators. With 10{sup 10}-10{sup 12} positrons per bunch, this low emittance beam, which is quasi-monoenergetic in the energy range of 5-20 MeV, may be useful as an alternative positron source for future accelerators.

Chen Hui; Hazi, A.; Link, A.; Anderson, S.; Gronberg, J.; Izumi, N.; Tommasini, R.; Wilks, S. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Sheppard, J. C. [SLAC, Standford University, Menlo Park, California 94025 (United States); Meyerhofer, D. D. [Laboratory for Laser Energetics, University of Rochester, Rochester, New York 14623 (United States); Baldis, H. A.; Marley, E.; Park, J.; Williams, G. J. [Department of Electrical and Computer Engineering, University of California, Davis, California 95616 (United States); Fedosejev, R.; Kerr, S. [Department of Applied Science, University of Alberta, Alberta T6G 2R3 (Canada)

2013-01-15

113

Thomson scattering measurement of a shock in laser-produced counter-streaming plasmas  

SciTech Connect

We report the first direct measurement of temporally and spatially resolved plasma temperatures at a shock as well as its spatial structure and propagation in laser-produced counter-streaming plasmas. Two shocks are formed in counter-streaming collisionless plasmas early in time, and they propagate opposite directions. This indicates the existence of counter-streaming collisionless flows to keep exciting the shocks, even though the collisional effects increase later in time. The shock images are observed with optical diagnostics, and the upstream and downstream plasma parameters of one of the shocks are measured using Thomson scattering technique.

Morita, T.; Kuramitsu, Y.; Moritaka, T. [Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan)] [Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan); Sakawa, Y.; Takabe, H. [Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan) [Institute of Laser Engineering, Osaka University, 2-6 Yamada-oka, Suita, Osaka 565-0871 (Japan); Graduate School of Science, Osaka University, 1-1 Machikane-yama, Toyonaka, Osaka 560-0043 (Japan); Tomita, K.; Nakayama, K.; Inoue, K.; Uchino, K. [Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 6-1, Kasugakoen, Kasuga, Fukuoka 816-8580 (Japan)] [Interdisciplinary Graduate School of Engineering Sciences, Kyushu University, 6-1, Kasugakoen, Kasuga, Fukuoka 816-8580 (Japan); Ide, T.; Tsubouchi, K. [Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan)] [Graduate School of Engineering, Osaka University, 2-1 Yamada-oka, Suita, Osaka 565-0871 (Japan); Nishio, K.; Ide, H.; Kuwada, M. [Graduate School of Science, Osaka University, 1-1 Machikane-yama, Toyonaka, Osaka 560-0043 (Japan)] [Graduate School of Science, Osaka University, 1-1 Machikane-yama, Toyonaka, Osaka 560-0043 (Japan)

2013-09-15

114

Ultrafast gated imaging of laser produced plasmas using the optical Kerr effect  

SciTech Connect

Optical imaging is a versatile diagnostic for investigations of plasmas generated under intense laser irradiation. Electro-optic gating techniques operating on the >100 ps timescale are commonly used to reduce the amount of light detected from self-emission of hot plasma or improve the temporal resolution of the detector. The use of an optical Kerr gate enables a superior dynamic range and temporal resolution compared to electronically gated devices. The application of this method for enhanced imaging of laser produced plasmas with gate time approx100 fs is demonstrated, and the possibility to produce a sub-10 fs, high dynamic range 'all optical' streak camera is discussed.

Symes, D. R.; Wegner, U.; Ahlswede, H.-C.; Streeter, M. J. V.; Gallegos, P. L.; Divall, E. J.; Rajeev, P. P.; Neely, D. [Central Laser Facility, Rutherford Appleton Laboratory, Chilton, Oxon OX11 0QX (United Kingdom); Smith, R. A. [Blackett Laboratory, Imperial College of Science, Technology and Medicine, Prince Consort Road, London SW7 2BZ (United Kingdom)

2010-01-04

115

Ultrafast gated imaging of laser produced plasmas using the optical Kerr effect  

NASA Astrophysics Data System (ADS)

Optical imaging is a versatile diagnostic for investigations of plasmas generated under intense laser irradiation. Electro-optic gating techniques operating on the >100 ps timescale are commonly used to reduce the amount of light detected from self-emission of hot plasma or improve the temporal resolution of the detector. The use of an optical Kerr gate enables a superior dynamic range and temporal resolution compared to electronically gated devices. The application of this method for enhanced imaging of laser produced plasmas with gate time ˜100 fs is demonstrated, and the possibility to produce a sub-10 fs, high dynamic range "all optical" streak camera is discussed.

Symes, D. R.; Wegner, U.; Ahlswede, H.-C.; Streeter, M. J. V.; Gallegos, P. L.; Divall, E. J.; Smith, R. A.; Rajeev, P. P.; Neely, D.

2010-01-01

116

Influence of Plasma Temperature on the Concentration of NO Produced by Pulsed Arc Discharge  

NASA Astrophysics Data System (ADS)

This study conducted experiments on producing inhaled medical nitric oxide (iNO) by pulsed arc discharge in dry and clean air under different discharge current. The concentration of NO and NO2 produced by air discharge, as well as the change of the ratio of NO2/NO under different discharge current were investigated. Through the analysis of plasma emission spectrum, the relationship between discharge current and arc plasma temperature was studied. The results indicate that, as discharge current increases, the arc plasma temperature increases, which then leads to the increase of NO concentration, the decrease of NO2 concentration, and the rapid decrease of the ratio of NO2/NO. When the plasma temperature is 9000 K, the ratio of NO2/NO is approximately 60%, while when the plasma temperature varies between 10550 K and 11300 K, the NO2/NO ratio is within the range of 4.2% to 4.6%.

Hu, Hui; Chen, Weipeng; Zhang, Jinli; Lu, Xi; He, Junjia

2012-03-01

117

Initiation, growth and plasma characteristics of ‘Gatchina’ water plasmoids  

NASA Astrophysics Data System (ADS)

Plasmoids generated by discharging a high-voltage capacitor through electrodes submerged in a weak aqueous electrolyte have attracted attention because of their resemblance to the natural phenomenon of ball lightning. We describe an extensive series of experimental studies which elucidate the mechanism responsible for the production of water plasmoids. We show that a plasma jet from a cathode spot is responsible for the formation of the main plasmoid, which grows in accordance with a current surge due to increasing contact area of the plasma with the liquid-air surface of the electrolyte. Spectra of optical emissions and scanning electron microscope studies indicate that the plasmoids glow because of a combination of chemiluminescence, atomic and molecular excitation, and possible incandescence from small particulates.

Stephan, Karl D.; Dumas, Shelby; Komala-Noor, Laurence; McMinn, Jonathan

2013-04-01

118

Equivalent ion temperature in Ta plasma produced by high energy laser ablation  

Microsoft Academic Search

High energy laser, 400 ps pulse duration, irradiating heavy targets in vacuum produce intense plasma and generate emission of various energetic ion groups. The ion intensity is high along the normal to the irradiated target surface and high charge state and high velocity ions are produced. The characteristics of the ion streams were investigated by using an electrostatic ion energy

L. Torrisi; S. Gammino; L. Andó; L. Laska; J. Krasa; K. Rohlena; J. Ullschmied; J. Wolowski; J. Badziak; P. Parys

2006-01-01

119

Precision closed bomb calorimeter for testing flame and gas producing initiators  

NASA Technical Reports Server (NTRS)

A calorimeter has been developed under this study to help meet the needs of accurate performance monitoring of electrically or mechanically actuated flame and gas producing devices, such as squib-type initiators. A ten cubic centimeter closed bomb (closed volume) calorimeter was designed to provide a standard pressure trace and to measure a nominal 50 calorie output, using the basic components of a Parr Model 1411 calorimeter. Two prototype bombs were fabricated, pressure tested to 2600 psi, and extensively evaluated.

Carpenter, D. R., Jr.; Taylor, A. C., Jr.

1972-01-01

120

Optimizing laser produced plasmas for efficient extreme ultraviolet and soft X-ray light sources  

SciTech Connect

Photon sources produced by laser beams with moderate laser intensities, up to 10{sup 14?}W/cm{sup 2}, are being developed for many industrial applications. The performance requirements for high volume manufacture devices necessitate extensive experimental research supported by theoretical plasma analysis and modeling predictions. We simulated laser produced plasma sources currently being developed for several applications such as extreme ultraviolet lithography using 13.5%?±?1% nm bandwidth, possibly beyond extreme ultraviolet lithography using 6.× nm wavelengths, and water-window microscopy utilizing 2.48?nm (La-?) and 2.88?nm (He-?) emission. We comprehensively modeled plasma evolution from solid/liquid tin, gadolinium, and nitrogen targets as three promising materials for the above described sources, respectively. Results of our analysis for plasma characteristics during the entire course of plasma evolution showed the dependence of source conversion efficiency (CE), i.e., laser energy to photons at the desired wavelength, on plasma electron density gradient. Our results showed that utilizing laser intensities which produce hotter plasma than the optimum emission temperatures allows increasing CE for all considered sources that, however, restricted by the reabsorption processes around the main emission region and this restriction is especially actual for the 6.×?nm sources.

Sizyuk, Tatyana; Hassanein, Ahmed [Center for Materials under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)

2014-08-15

121

Optimizing laser produced plasmas for efficient extreme ultraviolet and soft X-ray light sources  

NASA Astrophysics Data System (ADS)

Photon sources produced by laser beams with moderate laser intensities, up to 1014 W/cm2, are being developed for many industrial applications. The performance requirements for high volume manufacture devices necessitate extensive experimental research supported by theoretical plasma analysis and modeling predictions. We simulated laser produced plasma sources currently being developed for several applications such as extreme ultraviolet lithography using 13.5% ± 1% nm bandwidth, possibly beyond extreme ultraviolet lithography using 6.× nm wavelengths, and water-window microscopy utilizing 2.48 nm (La-?) and 2.88 nm (He-?) emission. We comprehensively modeled plasma evolution from solid/liquid tin, gadolinium, and nitrogen targets as three promising materials for the above described sources, respectively. Results of our analysis for plasma characteristics during the entire course of plasma evolution showed the dependence of source conversion efficiency (CE), i.e., laser energy to photons at the desired wavelength, on plasma electron density gradient. Our results showed that utilizing laser intensities which produce hotter plasma than the optimum emission temperatures allows increasing CE for all considered sources that, however, restricted by the reabsorption processes around the main emission region and this restriction is especially actual for the 6.× nm sources.

Sizyuk, Tatyana; Hassanein, Ahmed

2014-08-01

122

HEIGHTS initial simulation of discharge-produced plamsa hydrodynamics and radiation transport for EUV lithography  

NASA Astrophysics Data System (ADS)

Discharge produced plasma (DPP) devices have been proposed as a light source for EUV lithography. A key challenge for DPP is achieving sufficient brightness to support the throughput requirements of exposure tools for high-volume manufacturing lithography. To simulate the environment of the EUV source and optimize the output of the source, an integrated model is being developed to describe the hydrodynamic and optical processes that occur in DPP devices. The model includes both plasma evolution and magnetohydrodynamic processes as well as detailed photon radiation transport. The total variation diminishing scheme in the Lax-Friedrich formulation for the description of magnetic compression and diffusion in a cylindrical geometry is used. Several models are being developed for opacity calculations; a collisional radiation equilibrium model, a self-consistent field model with Auger processes, and a non-stationary kinetic model. Radiation transport for both continuum and lines with detailed spectral profiles are taken into account. The developed models are integrated into the HEIGHTS-EUV computer simulation package. Preliminary results of a numerical simulation of xenon gas hydrodynamics and line radiation output are presented for various plasma conditions.

Hassanein, Ahmed; Sizyuk, Valeryi; Tolkach, Vladimir; Morozov, Vitali; Rice, Bryan J.

2003-06-01

123

Experimental Results from Initial Operation of Plasma Injector 1  

NASA Astrophysics Data System (ADS)

General Fusion has begun operation of its first full-scale plasma injector, designed to accelerate high density spheromak plasmas into the compression chamber of a proposed MTF reactor. The geometry of Plasma Injector 1 (PI-1) is that of a two stage coaxial Marshal gun with a conical converging accelerator electrodes, similar in shape to the MARAUDER device, while pulsed power is applied in the same configuration as the RACE device. PI-1 is 5 meters in length and 1.9 m in diameter at the expansion region where a high aspect ratio (4.4) spheromak is formed with a minimum lambda of 9 m-1. The acceleration/compression stage is 4 m long and tapers to a final outer diameter of 40 cm. PI-1 is now operating at 1 MJ of total capacitor power, which will be doubled again before it reaches its design parameters. Diagnostics include 3 interferometer chords, 21 magnetic probes (2 axis poloidal/toroidal), 13 fast photodiode chords, as well as one Thomson scattering chord, a visible light survey spectrometer, and a Langmuir triple probe. Electrode voltage and current are also monitored. So far spheromaks of poloidal flux exceeding 100 mWb have been formed in the expansion region, and spheromaks of 40-50 mWb have been formed and accelerated out the end of the accelerator into a flux conserving target chamber. Expansion region densities are typically ˜5 x10^14cm-3, while conditions in the target chamber have reached ne˜10^16cm-3, and lifetimes of 300 ?s.

Howard, Stephen

2010-11-01

124

Comparison of initial value and eigenvalue codes for kinetic toroidal plasma instabilities  

Microsoft Academic Search

In plasma physics, linear instability calculations can be implemented either as initial value calculations or as eigenvalue calculations. Here, comparisons between comprehensive linear gyrokinetic calculations employing the ballooning formalism for high-n (toroidal mode number) toroidal instabilities are described. One code implements an initial value calculation on a grid using a Lorentz collision operator and the other implements an eigenvalue calculation

Mike Kotschenreuther; G. Rewoldt; W. M. Tang

1995-01-01

125

Stimulated forward Raman scattering in large scale-length laser-produced plasmas  

NASA Astrophysics Data System (ADS)

A forward stimulated Raman scattering (FSRS) diagnostic was developed for the 60 beam Omega laser facility to investigate the propagation of an intense ( ~ 8 × 1014 W/cm2), frequency doubled Nd:glass laser beam ( <= 360 J, 527 nm, 1 ns) through a mm-scale laser-produced plasma. Forward scattered light was measured with spectral, and temporal resolution using a streaked spectrometer and an absolutely calibrated photo-multiplier. We present a detailed description of the instrument, the calibration methods, as well as the first forward Raman scattering measurements from hot ( ~ 2 keV), dense (5.5 × 1020 cm-3) laser-produced plasmas. These results are of interest to laser-driven inertial fusion at the National Ignition Facility where larger plasma scales could potentially lead to higher FSRS gains. In addition, simultaneous measurements of stimulated forward and backward scattered light present an unambiguous method for determining plasma density and temperature.

Niemann, C.; Berger, R. L.; Divol, L.; Kirkwood, R. K.; Moody, J. D.; Sorce, C. M.; Glenzer, S. H.

2011-10-01

126

Late-time particle emission from laser-produced graphite plasma  

SciTech Connect

We report a late-time ''fireworks-like'' particle emission from laser-produced graphite plasma during its evolution. Plasmas were produced using graphite targets excited with 1064 nm Nd: yttrium aluminum garnet (YAG) laser in vacuum. The time evolution of graphite plasma was investigated using fast gated imaging and visible emission spectroscopy. The emission dynamics of plasma is rapidly changing with time and the delayed firework-like emission from the graphite target followed a black-body curve. Our studies indicated that such firework-like emission is strongly depended on target material properties and explained due to material spallation caused by overheating the trapped gases through thermal diffusion along the layer structures of graphite.

Harilal, S. S.; Hassanein, A.; Polek, M. [School of Nuclear Engineering, Center for Materials Under Extreme Environment, Purdue University, West Lafayette, Indiana 47907 (United States)

2011-09-01

127

Plasma catalytic hybrid processes: gas discharge initiation and plasma activation of catalytic processes  

Microsoft Academic Search

Catalytic reactions of a gas mixture can efficiently be induced by pre-treatment using a gas discharge plasma or by combined treatment in a plasma catalytic hybrid reactor. The effects of plasma treatment can be excitation of molecules, formation of short lived radicals, formation of long lived intermediate species, emission of UV-radiation, or simply gas heating.By dielectric barrier discharge (DBD) pre-treatment

Th. Hammer; Th. Kappes; M. Baldauf

2004-01-01

128

Measurement of Noise Produced by a Plasma Contactor Operating in Ground Based Facilities  

NASA Technical Reports Server (NTRS)

Methods to measure electric field fluctuations accurately in a plasma with an active monopole antenna are described. It is shown that the conductive surfaces of the antenna must be adequately isolated from the ambient plasma and that the monopole must be sufficiently short to avoid antenna amplifier saturation. Experimental results illustrate that the noise produced by plasma contactor operation and sensed by the antenna is due to plasma phenomena and is not induced by laboratory power supplies. A good correlation is shown between the current fluctuations in the contactor electrical circuit and the noise detected by the antenna. A large body of experimental data support the conclusion that the majority of noise sensed by the antenna at frequencies less than 1 MHz is due to current fluctuations (electrostatic waves) in the plasma adjacent to the antenna and not to electromagnetic wave radiation. Caution is suggested when comparing antenna noise measurements to conventional specifications for radiated emissions.

Snyder, Steve

1996-01-01

129

Laser beam propagation, filamentation and channel formation in laser-produced plasmas  

SciTech Connect

The understanding of laser beam propagation through underdense plasmas is of vital importance to laser-plasma interaction experiments, as well as being a fundamental physics issue. Formation of plasma channels has numerous applications including table-top x- ray lasers and laser-plasma-produced particle accelerators. The fast ignitor concept, for example, requires the formation of an evacuated channel through a large, underdense plasma. Scaled experiments have shown that the axial extent of a channel formed by a 100 ps pulse is limited by the onset of the filamentation instability. We have obtained quantitative comparison between filamentation theory and experiment. More recent experiments have shown that by increasing the duration of the channel-forming pulse, the filamentation instability is overcome and the channel extent is substantially increased. This result has important implications for the fast ignitor design and the understanding of time-dependent beam dynamics.

Young, P.E.; Wilks, S.C.; Kruer, L.L.; Hammer, J.H.; Guethlein, G.; Foord, M.E.

1996-03-01

130

Rapidly solidified thick stainless cast iron alloy deposit with niobium carbide particles produced by plasma spraying  

Microsoft Academic Search

In plasma spraying process, spray material is heated, melted and accelerated by a high temperature flame. Low-pressure plasma spraying can produce rapidly solidified thick materials because alloy droplets accumulate successively on the substrate, and solidify at a cooling rate in the range of 105–108ks?1. Depending on the cooling conditions of the substrate and on the alloy composition, deposits can be

Yasuhiro Hoshiyama; Tsutomu Miyazaki; Hidekazu Miyake

2011-01-01

131

Modeling X-Ray Photoionized Plasmas Produced at the Sandia Z-Facility  

Microsoft Academic Search

In experiments at the high-power Z-facility at Sandia National Laboratory in Albuquerque, New Mexico, we have been able to produce a low density photoionized laboratory plasma of Fe mixed with NaF. The conditions in the experiment allow a meaningful comparison with X-ray emission from astrophysical sources. The charge state distributions of Fe, Na and F are determined in this plasma

P. A. M. Hoof; M. E. Foord; R. F. Heeter; J. E. Bailey; H.-K. Chung; M. E. Cuneo; W. H. Goldstein; V. Jonauskas; F. P. Keenan; R. Kisielius; D. A. Liedahl; C. Ramsbottom; S. J. Rose; P. T. Springer; R. S. Thoe

2005-01-01

132

On the atomic state densities of plasmas produced by the ``torche à injection axiale''  

NASA Astrophysics Data System (ADS)

The atomic state densities of helium and argon plasmas produced by the microwave driven plasma torch called the "torche à injection axiale" are presented. They are obtained by absolute line intensity measurements of the excited states and by applying the ideal gas law to the ground state. It will be shown that the atomic state distribution function (ASDF) does not obey the Saha-Boltzmann law: the ASDF cannot be described by one temperature. From the shape of the ASDF it can be concluded that the plasma is ionising. By extrapolating the measured state densities towards the ionisation limit, a minimum value of the electron density can be determined.

Jonkers, J.; Vos, H. P. C.; van der Mullen, J. A. M.; Timmermans, E. A. H.

1996-04-01

133

Medium- and long-wavelength infrared emission from a laser-produced oxygen plasma  

NASA Astrophysics Data System (ADS)

Experiments on a laser-produced oxygen plasma were observed by medium wavelength (MWIR) and long wavelength (LWIR) infrared emission. This research is part of a continuing series of LINUS (Laser Induced Nuclear Simulation) experiments starting in the short wavelength infrared (SWIR) and extended to longer wavelengths to continue studies on highly excited oxygen atom states produced by three-body recombination in a highly ionized, laser-produced plasma. The first observations of emission in the 5 to 8 micron region from a recombining oxygen plasma are reported, including the first experimental observation of 6h sup 3,5H yields 5g sup 3,5G sup 0 and 6g sup 3,5G sup 0 yields 5f sup 3,5 F calculated to be at 7.450 microns and 7.426 microns, respectively. The observed linewidths of these MWIR emissions are discussed using a Stark lineshape analysis.

Lurie, J. B.; Baird, J. C.

1985-12-01

134

Convection of Plasmaspheric Plasma into the Outer Magnetosphere and Boundary Layer Region: Initial Results  

NASA Technical Reports Server (NTRS)

We present initial results on the modeling of the circulation of plasmaspheric-origin plasma into the outer magnetosphere and low-latitude boundary layer (LLBL), using a dynamic global core plasma model (DGCPM). The DGCPM includes the influences of spatially and temporally varying convection and refilling processes to calculate the equatorial core plasma density distribution throughout the magnetosphere. We have developed an initial description of the electric and magnetic field structures in the outer magnetosphere region. The purpose of this paper is to examine both the losses of plasmaspheric-origin plasma into the magnetopause boundary layer and the convection of this plasma that remains trapped on closed magnetic field lines. For the LLBL electric and magnetic structures we have adopted here, the plasmaspheric plasma reaching the outer magnetosphere is diverted anti-sunward primarily along the dusk flank. These plasmas reach X= -15 R(sub E) in the LLBL approximately 3.2 hours after the initial enhancement of convection and continues to populate the LLBL for 12 hours as the convection electric field diminishes.

Ober, Daniel M.; Horwitz, J. L.

1998-01-01

135

Convection of Plasmaspheric Plasma into the Outer Magnetosphere and Boundary Layer Region: Initial Results  

NASA Technical Reports Server (NTRS)

We present initial results on the modeling of the circulation of plasmaspheric- origin plasma into the outer magnetosphere and low-latitude boundary layer (LLBL), using a dynamic global core plasma model (DGCPM). The DGCPM includes the influences of spatially and temporally varying convection and refilling processes to calculate the equatorial core plasma density distribution throughout the magnetosphere. We have developed an initial description of the electric and magnetic field structures in the outer magnetosphere region. The purpose of this paper is to examine both the losses of plasmaspheric-origin plasma into the magnetopause boundary layer and the convection of this plasma that remains trapped on closed magnetic field lines. For the LLBL electric and magnetic structures we have adopted here, the plasmaspheric plasma reaching the outer magnetosphere is diverted anti-sunward primarily along the dusk flank. These plasmas reach X = -15 R(sub E) in the LLBL approximately 3.2 hours after the initial enhancement of convection and continues to populate the LLBL for 12 hours as the convection electric field diminishes.

Ober, Daniel M.; Horwitz, J. L.; Gallagher, D. L.

1998-01-01

136

Apparatus and method to enhance X-ray production in laser produced plasmas  

DOEpatents

Method and apparatus for generating x-rays for use in, for instance, x-ray photolithography. The method of generating x-rays includes the steps of providing a target and irradiating the target with a laser system which produces a train of sub-pulses to generate an x-ray producing plasma. The sub-pulses are of both high intensity and short duration. The apparatus for generating x-rays from a plasma includes a vacuum chamber, a target supported within the chamber and a laser system, including a short storage time laser.

Augustoni, Arnold L. (Albuquerque, NM); Gerardo, James B. (Albuquerque, NM); Raymond, Thomas D. (Albuquerque, NM)

1992-01-01

137

Efficient extreme ultraviolet emission from one-dimensional spherical plasmas produced by multiple lasers  

NASA Astrophysics Data System (ADS)

We demonstrate high conversion efficiency for extreme ultraviolet (EUV) emission at 6.5-6.7 nm from multiple laser beam-produced one-dimensional spherical plasmas. Multiply charged-state ions produce strong resonance emission lines, which combine to yield intense unresolved transition arrays (UTAs) in Gd, Tb, and Mo. At an optimum laser intensity of 1 × 1012 W/cm2, which is estimated to yield an electron temperature of around 100 eV, the maximum in-band EUV conversion efficiency (CE) was observed to be 0.8%, which is one of the highest values ever reported due to the reduction of plasma expansion loss.

Yoshida, Kensuke; Fujioka, Shinsuke; Higashiguchi, Takeshi; Ugomori, Teruyuki; Tanaka, Nozomi; Ohashi, Hayato; Kawasaki, Masato; Suzuki, Yuhei; Suzuki, Chihiro; Tomita, Kentaro; Hirose, Ryoichi; Ejima, Takeo; Nishikino, Masaharu; Sunahara, Atsushi; Scally, Enda; Li, Bowen; Yanagida, Tatsuya; Nishimura, Hiroaki; Azechi, Hiroshi; O'Sullivan, Gerry

2014-08-01

138

[Preliminary study of atomic emission spectrometry of Ti (H) plasma produced by vacuum arc ion source].  

PubMed

In order to study the discharge process of vacuum arc ion source, make a detail description of the discharge plasma, and lay the foundation for further research on ion source, atomic emission spectrometry was used to diagnose the parameters of plasma produced by vaccum arc ion source. In the present paper, two kinds of analysis method for the emission spectra data collected by a spectrometer were developed. Those were based in the stark broadening of spectral lines and Saba-Boltzmann equation. Using those two methods, the electron temperature, electron number density and the ion temperature of the plasma can be determined. The emission spectroscopy data used in this paper was collected from the plasma produced by a vacuum are ion source whose cathode was made by Ti material (which adsorbed hydrogen during storage procedure). Both of the two methods were used to diagnose the plasma parameters and judge the thermal motion state of the plasma. Otherwise, the validity of the diagnostic results by the two methods were analyzed and compared. In addition, the affection from laboratory background radiation during the spectral acquisition process was discussed. PMID:25208416

Deng, Chun-Feng; Wu, Chun-Lei; Wang, Yi-Fu; Lu, Biao; Wen, Zhong-Wei

2014-03-01

139

Production of geopolymers using glass produced from DC plasma treatment of air pollution control (APC) residues  

Microsoft Academic Search

Air pollution control (APC) residues are the hazardous waste produced from cleaning gaseous emissions at energy-from-waste (EfW) facilities processing municipal solid waste (MSW). APC residues have been blended with glass-forming additives and treated using DC plasma technology to produce a high calcium alumino-silicate glass. This research has investigated the optimisation and properties of geopolymers prepared from this glass. Work has

Ioanna Kourti; D. Amutha Rani; D. Deegan; A. R. Boccaccini; C. R. Cheeseman

2010-01-01

140

X-Ray Crystal Spectroscopy of Subpicosecond Laser-Produced Plasmas beyond 50 keV  

Microsoft Academic Search

The interaction of a sub-picosecond (sub-ps) laser with a high-Ztarget produces a hard x-ray continuum, but to our knowledge no high-resolution study of the line emission is known. We present here crystal spectroscopy as a tool for the observation of energetic line x-radiation from a sub-ps laser-produced plasma. Reflection properties of flat and bent crystals for x-ray spectroscopy are analyzed

G. Hölzer; E. Förster; M. Grätz; C. Tillman; S. Svanberg

1997-01-01

141

Three-dimensional simulation of laser-produced plasma for extreme ultraviolet lithography applications  

SciTech Connect

Laser-produced plasma (LPP) from a tin target is being considered as the light source for the next generation of extreme ultraviolet (EUV) lithography. An integrated model was developed to simulate the plasma behavior and the EUV radiation output in LPP devices. The model includes plasma heat conduction and hydrodynamic processes in a two-temperature approximation, as well as detailed photon radiation transport using Monte Carlo methods. Multiple laser beams incident on a single target have been simulated in full three-dimensional geometry, using the total variation-diminishing scheme for the plasma hydrodynamics and an implicit scheme for heat conduction processes. Numerical simulations showed that EUV conversion efficiency increases for multiple-beam devices with specific optimum laser locations and direction compared to a single-beam device.

Sizyuk, V.; Hassanein, A.; Sizyuk, T. [Argonne National Laboratory, 9700 South Cass Avenue, Argonne, Illinois 60439 (United States)

2006-11-15

142

Analysis of atomic and ion debris features of laser-produced Sn and Li plasmas  

SciTech Connect

Tin and lithium plasmas emit efficiently in the in-band region (13.5 nm with 2% bandwidth) necessary for extreme ultraviolet (EUV) lithography. We have made a detailed comparison of the atomic and ionic debris, as well as the emission features of Sn and Li plasmas under identical experimental conditions. Planar slabs of pure Sn and Li were irradiated with 1064 nm, 9 ns neodymium-doped yttrium aluminum garnet laser pulses for producing plasmas. A suite of diagnostics were used to analyze the emission and debris features, including optical emission spectroscopy (OES), a Faraday cup, an EUV pinhole camera, the absolute measurement of EUV conversion efficiency (CE), etc. Our results show that Sn plasmas provide a CE nearly twice that of Li. However, the kinetic energies of Sn ions are considerably higher, though with a lower flux. OES studies have showed that the kinetic energies of neutral species are substantially lower compared to that of the charged particle species.

Coons, R. W.; Harilal, S. S.; Campos, D.; Hassanein, A. [School of Nuclear Engineering and Center for Materials Under Extreme Environment, Purdue University, West Lafayette, Indiana 47907 (United States)

2010-09-15

143

Ion shock acceleration by large amplitude slow ion acoustic double layers in laser-produced plasmas  

SciTech Connect

A kinetic model for the shock acceleration of ions in laser-produced plasmas is developed. A fraction of the warm ions are accelerated by the large amplitude monotonic potential of the shock created due the plasma compression and electron heating by the laser. The kinetic model for the monotonic shock is based on the slow ion acoustic double layer (SIADL). It is found that the amplitude of the large amplitude SIADL is almost uniquely defined by the electron temperature. Therefore, a balance between electron heating and plasma compression is needed for optimal ion acceleration by this scheme. Typical Mach numbers of the monotonic shocks are close to 1.5. The scheme could potentially produce monoenergetic ions with a relative energy spread of less than 1%. The model is compared with recent simulations and experiments, where efficient shocks acceleration and production of monoenergetic protons have been observed. Similarities and differences with other shock models are pointed out and discussed.

Eliasson, B. [SUPA, Physics Department, University of Strathclyde, John Anderson Building, Glasgow G4 0NG (United Kingdom)] [SUPA, Physics Department, University of Strathclyde, John Anderson Building, Glasgow G4 0NG (United Kingdom)

2014-02-15

144

Ion shock acceleration by large amplitude slow ion acoustic double layers in laser-produced plasmas  

NASA Astrophysics Data System (ADS)

A kinetic model for the shock acceleration of ions in laser-produced plasmas is developed. A fraction of the warm ions are accelerated by the large amplitude monotonic potential of the shock created due the plasma compression and electron heating by the laser. The kinetic model for the monotonic shock is based on the slow ion acoustic double layer (SIADL). It is found that the amplitude of the large amplitude SIADL is almost uniquely defined by the electron temperature. Therefore, a balance between electron heating and plasma compression is needed for optimal ion acceleration by this scheme. Typical Mach numbers of the monotonic shocks are close to 1.5. The scheme could potentially produce monoenergetic ions with a relative energy spread of less than 1%. The model is compared with recent simulations and experiments, where efficient shocks acceleration and production of monoenergetic protons have been observed. Similarities and differences with other shock models are pointed out and discussed.

Eliasson, B.

2014-02-01

145

Influence of spot size on extreme ultraviolet efficiency of laser-produced Sn plasmas  

SciTech Connect

We have investigated the spot size effects on the extreme ultraviolet conversion efficiency (CE) of CO{sub 2} laser-produced Sn plasmas. The estimated CE of the laser to 13.5 nm radiation, within a 2% bandwidth, using a 10.6 {mu}m CO{sub 2} laser with various pulse widths (25-55 ns) showed a double hump structure during a target-lens scan, where the CE is nearly 25% lower at the best focal position. Density analysis of the CO{sub 2} laser-produced plasma showed steep density gradients at the best focal position, and a reduction in CE at the best focal position, which is explained by the lack of efficient coupling between the laser and the plasma.

Harilal, S. S.; Coons, R. W.; Hassanein, A. [School of Nuclear Engineering and Center for Materials Under Extreme Environment, Purdue University, 400 Central Dr., West Lafayette, Indiana 47907 (United States); Hough, P. [School of Physical Sciences and National Centre for Plasma Science and Technology, Dublin City University, Dublin 9 (Ireland)

2009-11-30

146

Experimental studies of radiatively cooled supersonic plasma jets produced in wire array z-pinches  

NASA Astrophysics Data System (ADS)

We will present results of recent experiments with radiatively cooled supersonic plasma jets performed on the pulsed power MAGPIE facility (1.5MA, 250ns) at Imperial College. The jets are produced by the plasma ablated from the wires arranged in conical or radial configurations. Convergence of the flow on the axis of symmetry of the system produces plasma jets with dimensionless parameters (Mach number ˜20, cooling parameter ˜1) similar to those in proto-stellar jets, and the flow has high Reynolds number (>10^5). We will present measurements of the jet parameters obtained with laser and XUV diagnostics providing high spatial resolution, and will discuss how this set-up can be scaled to 20MA Z facility.

Lebedev, Sergey; Suzuki-Vidal, F. A.; de Grouchy, P.; Swadling, G.; Bocchi, M.; Ciardi, A.; Bland, S. N.; Bott, S.; Burdiak, G.; Chittenden, J. P.; Hall, G. N.; Harvey-Thomson, A.; Frank, A.

2010-11-01

147

Signal processing algorithm for simultaneous multielement analysis by laser-produced plasma spectroscopy  

NASA Astrophysics Data System (ADS)

We developed a signal processing algorithm to analyze the signals obtained by an OMA system for laser-produced plasmas. This signal processing program is applied for multi- component analysis of trace elements in particulate materials (e.g. soils and industrial wastes) and is designed to overcome signal fluctuations due to instability of the plasma characteristics and due to some of the matrix effects. The program involves a constrained normalization algorithm, an automatic peak assignment, a functional fit of all peaks of interest and their surroundings, and a principal components regression calibration model. These algorithms, together with experimental optimizations, are shown to solve most of the problems present in laser plasma analysis of particulate material and to produce detection limits in the ppm range.

Schechter, Israel; Wisbrun, Richard W.; Niessner, Reinhard; Schroeder, Hartmut; Kompa, Karl L.

1994-02-01

148

Transient loss of plasma from a theta pinch having an initially reversed magnetic field  

SciTech Connect

The results of an experimental study of the transient loss of plasma from a 25-cm-long theta pinch initially containing a reversed trapped magnetic field are presented. The plasma, amenable to MHD analyses, was a doubly ionized helium plasma characterized by an ion density N/sub i/ = 2 x 10/sup 16/ cm/sup -3/ and an ion temperature T/sub i/ = 15 eV at midcoil and by N/sub i/ = 0.5 x 10/sup 16/ cm/sup -3/ and T/sub i/ = 6 eV at a position 2.5 cm beyond the end of the theta coil.

Heidrich, J. E.

1981-01-01

149

Direct energy converter from laser energy to electricity with laser-produced plasma  

Microsoft Academic Search

A method of power transmission using a laser beam for a very long distance has been proposed. The characteristics of the direct energy converter from laser energy to electricity with laser-produced plasma are reported here. It is found that the efficiency of eta 1. eta 3(max) (where eta 1 and eta 3 are the conversion efficiency from laser energy to

Hiroshi Homma; Tatsuo Okamoto; Masao Yamauchi; Chobei Yamabe; Kenji Horii

1988-01-01

150

Observation of laser satellites in a plasma produced by a femtosecond laser pulse  

E-print Network

Observation of laser satellites in a plasma produced by a femtosecond laser pulse S. A. Pikuz P. N­459 10 October 1997 Laser satellites are detected in the emission spectra of magnesium and aluminum they called laser satellites, should appear in the emission spectrum of an ion placed in a strong laser field

Umstadter, Donald

151

Emission characteristics and dynamics of C2 from laser produced graphite plasma  

E-print Network

Emission characteristics and dynamics of C2 from laser produced graphite plasma S. S. Harilal, Riju 1996; accepted for publication 20 December 1996 The emission features of laser ablated graphite plume. INTRODUCTION Pulsed laser ablation of graphite has become well estab- lished as a reliable method

Harilal, S. S.

152

Single-shot two-dimensional spectral interferometry for ultrafast laser-produced plasmas.  

PubMed

Coherent white light was used as a light source for spectral interferometry of ultrafast laser-produced plasmas. Using a narrowband filter, two-dimensional images of field ionization in helium were obtained with a 14 fs time resolution. PMID:16729114

Hama, Y; Kondo, K; Zoubir, A; Honda, T; Kodama, R; Tanaka, K A; Mima, K

2006-06-15

153

Effects of plasma treatment to nanofibers on initial cell adhesion and cell morphology.  

PubMed

Poly-L-lactic acid (PLLA) nanofibers were fabricated by electrospinning and treated with O2 plasma. The surface properties of PLLA nanofibers before and after plasma treatment were characterized by water contact angle measurement and X-ray photoelectron spectroscopy (XPS). It was found that the hydrophilicity of PLLA nanofibers was improved and the amount of oxygen-containing groups increased after plasma treatment. Initial cell adhesion was evaluated by cell capture efficiency based on the cell count method. The results showed that initial porcine mesenchymal stem cells (pMSCs) adhesion to plasma-treated nanofibers was significantly enhanced. Moreover, the morphology of pMSCs on PLLA nanofibers (PLLA NFS) and plasma-treated PLLA nanofibers (P-PLLA NFS) were observed by scanning electron microscope (SEM) after 10 min, 20 min, 30 min and 60 min cell adhesion. It was found that plasma treatment to electrospun nanofibers had a great effect on pMSCs morphology at earlier time points. Therefore, plasma treatment is an efficient surface modification strategy to improve cell adhesion in earlier culture time intervals. It may be a promising method in the design of novel tissue-engineered scaffolds. PMID:24060934

Liu, Wei; Zhan, Jianchao; Su, Yan; Wu, Tong; Wu, Chunchen; Ramakrishna, Seeram; Mo, Xiumei; Al-Deyab, Salem S; El-Newehy, Mohamed

2014-01-01

154

Plasma Reforming And Partial Oxidation Of Hydrocarbon Fuel Vapor To Produce Synthesis Gas And/Or Hydrogen Gas  

DOEpatents

Methods and systems are disclosed for treating vapors from fuels such as gasoline or diesel fuel in an internal combustion engine, to form hydrogen gas or synthesis gas, which can then be burned in the engine to produce more power. Fuel vapor, or a mixture of fuel vapor and exhaust gas and/or air, is contacted with a plasma, to promote reforming reactions between the fuel vapor and exhaust gas to produce carbon monoxide and hydrogen gas, partial oxidation reactions between the fuel vapor and air to produce carbon monoxide and hydrogen gas, or direct hydrogen and carbon particle production from the fuel vapor. The plasma can be a thermal plasma or a non-thermal plasma. The plasma can be produced in a plasma generating device which can be preheated by contact with at least a portion of the hot exhaust gas stream, thereby decreasing the power requirements of the plasma generating device.

Kong, Peter C. (Idaho Falls, ID); Detering, Brent A. (Idaho Falls, ID)

2004-10-19

155

System to continuously produce carbon fiber via microwave assisted plasma processing  

DOEpatents

A system to continuously produce fully carbonized or graphitized carbon fibers using microwave-assisted plasma (MAP) processing comprises an elongated chamber in which a microwave plasma is excited in a selected gas atmosphere. Fiber is drawn continuously through the chamber, entering and exiting through openings designed to minimize in-leakage of air. There is a gradient of microwave power within the chamber with generally higher power near where the fiber exits and lower power near where the fiber enters. Polyacrylonitrile (PAN), pitch, or any other suitable organic/polymeric precursor fibers can be used as a feedstock for the inventive system. Oxidized or partially oxidized PAN or pitch or other polymeric fiber precursors are run continuously through a MAP reactor in an inert, non-oxidizing atmosphere to heat the fibers, drive off the unwanted elements such as oxygen, nitrogen, and hydrogen, and produce carbon or graphite fibers faster than conventionally produced carbon fibers.

White, Terry L. (Knoxville, TN) [Knoxville, TN; Paulauskas, Felix L. (Knoxville, TN) [Knoxville, TN; Bigelow, Timothy S. (Knoxville, TN) [Knoxville, TN

2010-11-02

156

Numerical modeling of initiation of lightning leaders from tall structures by sprite-producing lightning discharges  

NASA Astrophysics Data System (ADS)

It is well established by now that large charge transfers between cloud and ground in positive cloud-to-ground lightning discharges (+CGs) can lead to transient electric field enhancements at mesospheric and lower ionospheric altitudes. In these events the electric field can exceed the conventional breakdown field and lead to formation of transient luminous events referred to as sprites and sprite halos [e.g., Qin et al., JGR, 116, A06305, 2011, and references therein]. Stanley and Heavner [Proc. 12th International Conference on Atmospheric Electricity, Versailles, France, 2003] reported that the large and rapid charge transfer of +CGs producing sprites can also initiate upward positive leaders from tall structures. These authors also presented data analysis indicating that structures with >400 m height have a significantly enhanced probability of launching upward positive leaders that may culminate in a -CG return stroke to the structure. The effect can be understood by considering the field intensification at the top of the tall structure combined with fast application of the field preventing formation and shielding effects of ion corona [Brook et al., JGR, 66, 3967, 1961]. In the present work we utilize the most recent modeling approaches developed at Penn State [e.g., Riousset et al., JGR, 115, A00E10, 2010] to quantify the conditions leading to initiation of positive leaders from tall structures following sprite-producing +CGs. Experiments show that the streamer zone transforms into leader when voltage drop along the streamer zone exceeds 400 kV [e.g., Aleksandrov et al., J. Phys. D: Appl. Phys., 38, 1225, 2005]. For a formed leader half of the voltage drops in the streamer zone, and another half in free space ahead of the streamer zone [Bazelyan and Raizer, Lightning physics and lightning protection, p. 62, 2000]. In our analysis therefore we assume that minimum voltage at the tip of the tower should exceed 800 kV for sustainment of upward propagating leader. The results indicate, in particular, that a charge moment change of 390 C km in a +CG can lead to leader initiation from a 457 m tower approximately 15 km from the +CG, in good agreement with observations reported in [Stanley and Heavner, 2003]. We report detailed relationships, including analytical estimates and numerical modeling results, providing information on the charge moment charges versus tower height and radial position with respect to +CG required for initiation of upward leaders.

Pasko, V. P.

2011-12-01

157

Pilot scale test of a produced water-treatment system for initial removal of organic compounds  

SciTech Connect

A pilot-scale test to remove polar and non-polar organics from produced water was performed at a disposal facility in Farmington NM. We used surfactant-modified zeolite (SMZ) adsorbent beds and a membrane bioreactor (MBR) in combination to reduce the organic carbon content of produced water prior to reverse osmosis (RO). Reduction of total influent organic carbon (TOC) to 5 mg/L or less is desirable for efficient RO system operation. Most water disposed at the facility is from coal-bed gas production, with oil production waters intermixed. Up to 20 gal/d of produced water was cycled through two SMZ adsorbent units to remove volatile organic compounds (BTEX, acetone) and semivolatile organic compounds (e.g., napthalene). Output water from the SMZ units was sent to the MBR for removal of the organic acid component of TOC. Removal of inorganic (Mn and Fe oxide) particulates by the SMZ system was observed. The SMZ columns removed up to 40% of the influent TOC (600 mg/L). BTEX concentrations were reduced from the initial input of 70 mg/L to 5 mg/L by the SMZ and to an average of 2 mg/L after the MBR. Removal rates of acetate (input 120-170 mg/L) and TOC (input up to 45 mg/L) were up to 100% and 92%, respectively. The water pH rose from 8.5 to 8.8 following organic acid removal in the MBR; this relatively high pH was likely responsible for observed scaling of the MBR internal membrane. Additional laboratory studies showed the scaling can be reduced by metered addition of acid to reduce the pH. Significantly, organic removal in the MBR was accomplished with a very low biomass concentration of 1 g/L throughout the field trial. An earlier engineering evaluation shows produced water treatment by the SMZ/MBR/RO system would cost from $0.13 to $0.20 per bbl at up to 40 gpm. Current estimated disposal costs for produced water are $1.75 to $4.91 per bbl when transportation costs are included, with even higher rates in some regions. Our results suggest that treatment by an SMZ/MBR/RO system may be a feasible alternative to current methods for produced water treatment and disposal.

Sullivan, Enid J [Los Alamos National Laboratory; Kwon, Soondong [UT-AUSTIN; Katz, Lynn [UT-AUSTIN; Kinney, Kerry [UT-AUSTIN

2008-01-01

158

Studies of extreme ultraviolet emission from laser produced plasmas, as sources for next generation lithography  

NASA Astrophysics Data System (ADS)

The work presented in this thesis is primarily concerned with the optimisation of extreme ultraviolet (EUV) photoemission around 13.5 nm, from laser produced tin (Sn) plasmas. EUV lithography has been identified as the leading next generation technology to take over from the current optical lithography systems, due to its potential of printing smaller feature sizes on integrated circuits. Many of the problems hindering the implementation of EUV lithography for high volume manufacturing have been overcome during the past 20 years of development. However, the lack of source power is a major concern for realising EUV lithography and remains a major roadblock that must be overcome. Therefore in order to optimise and improve the EUV emission from Sn laser plasma sources, many parameters contributing to the make-up of an EUV source are investigated. Chapter 3 presents the results of varying several different experimental parameters on the EUV emission from Sn laser plasmas. Several of the laser parameters including the energy, gas mixture, focusing lens position and angle of incidence are changed, while their effect on the EUV emission is studied. Double laser pulse experiments are also carried out by creating plasma targets for the main laser pulse to interact with. The resulting emission is compared to that of a single laser pulse on solid Sn. Chapter 4 investigates tailoring the CO2 laser pulse duration to improve the efficiency of an EUV source set-up. In doing so a new technique for shortening the time duration of the pulse is described. The direct effects of shortening the CO2 laser pulse duration on the EUV emission from Sn are then studied and shown to improve the efficiency of the source. In Chapter 5 a new plasma target type is studied and compared to the previous dual laser experiments. Laser produced colliding plasma jet targets form a new plasma layer, with densities that can be optimised for re-heating with the main CO2 laser pulse. Chapter 6 will present some experiments carried out on laser produced gadolinium plasmas, with its photoemission around 6.7 nm seen as a potential beyond EUV source. Three different laser pulse durations and a range of laser intensities are utilised in experiments to try to optimise the in-band emission, while also observing the effect on ion emission from the plasma. Finally, the experiments presented in thesis and their results are summarised in Chapter 7, along with presenting possible future work.

Cummins, Thomas

159

Directional elliptically polarized terahertz emission from air plasma produced by circularly polarized intense femtosecond laser pulses  

SciTech Connect

We have observed directional elliptically polarized terahertz (THz) waves emitted from air plasma produced by circularly polarized femtosecond laser pulses. The spatial distribution of the THz waves shows that the radiation is strongly directed forward with a peak around the laser propagation direction. Measured THz power shows a square dependence on laser energy. We consider the parametric decay of laser light to R-waves in plasma in the presence of a spontaneous magnetic field as a possible explanation for the polarization, power dependence, and direction of the THz beam.

Jahangiri, Fazel; Hashida, Masaki; Tokita, Shigeki; Sakabe, Shuji [Advanced Research Center for Beam Science, ICR, Kyoto University, Gokasho, Uji, Kyoto 611-0011, Japan and Department of Physics, GSS, Kyoto University, Kitashirakawa, Sakyo, Kyoto 606-7501 (Japan); Nagashima, Takeshi; Hangyo, Masanori [Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka, Suita, Osaka 565-0871 (Japan)

2011-10-17

160

Design of a Microwave-Initiated Pulsed Plasma Thruster Jian F. Li, Class of 2006  

E-print Network

the inductance of the discharge circuit, improving tuning of the microwave cavity, and developing a system of discharge symmetry in the spark-ignition mechanism of GFPPTs has lead to non-uniform current sheet formation microwave discharges as an plasma initiation source in GFPPTs. The purpose of this project is to design

Choueiri, Edgar

161

Epithelial overexpression of BDNF and NT4 produces distinct gustatory axon morphologies that disrupt initial targeting  

PubMed Central

Most fungiform taste buds fail to become innervated when BDNF or NT4 is overexpressed in the basal layer of tongue epithelium. Here, we examined when and how overexpression of BDNF and NT4 disrupt innervation to fungiform papillae. Overexpression of either factor disrupted chorda tympani innervation patterns either before or during the initial innervation of fungiform papillae. NT4 and BDNF overexpression each disrupted initial innervation by producing different gustatory axon morphologies that emerge at distinct times (E12.5 and E14.5, respectively). Chorda tympani nerve branching was reduced in NT4 overexpressing mice, and neuronal fibers in these mice were fasciculated and remained below the epithelial surface, as if repelled by NT4 overexpression. In contrast, many chorda tympani nerve branches were observed near the epithelial surface in mice overexpressing BDNF, and most were attracted to and invaded non-taste filiform papillae instead of gustatory papillae. These results suggest that BDNF, but not NT4, normally functions as a chemoattractant that allows chorda tympani fibers to distinguish their fungiform papillae targets from non-gustatory epithelium. Since BDNF and NT4 both signal through the p75 and TrkB receptors, trophin-specific activation of different internal signaling pathways must regulate the development of the distinct gustatory axon morphologies in neurotrophin-overexpressing mice. PMID:16500639

Lopez, Grace F.; Krimm, Robin F.

2007-01-01

162

PHYSICAL REVIEW E 86, 056407 (2012) Characterization of single and colliding laser-produced plasma bubbles using Thomson  

E-print Network

plasma, where the release of magnetic energy (thermal energy) does not appreciablyPHYSICAL REVIEW E 86, 056407 (2012) Characterization of single and colliding laser-produced plasma. J. Town,2 F. H. S´eguin,1 J. A. Frenje,1 D. H. Froula,3 and R. D. Petrasso1 1 Plasma Science

163

Plasma potential control: initial results from tandem mirror experiment-upgrade  

SciTech Connect

Initial plasma potential control experiments used plates in the end fan, insulated from the end walls of TMX-U, which mapped along field lines to the plasma core (r/sub c/ less than or equal to 12.9 cm). Measurements in which these plates are shorted to ground during plugging demonstrate that floating the plates increases the buildup rate of the central cell plasma, steepens the core density profile, and affects the plasma throughout the entire cross section. Floating the plates decreases the ion radial transport rate in the core by a factor of at least 1.5. Because of these encouraging results, in the next series of experiments more plates will be added, extending to a larger radius (r/sub c/ less than or equal to 19.4 cm).

Hopper, E.B. Jr.

1984-02-28

164

Initial Speed of Knots in the Plasma Tail of C/2013 R1(Lovejoy)  

E-print Network

We report short-time variations in the plasma tail of C/2013 R1(Lovejoy). A series of short (2-3 minutes) exposure images with the 8.2-m Subaru telescope shows faint details of filaments and their motions. We identified rapid movements of two knots in the plasma tail near the nucleus (~ 3x10^5 km). Their speeds are 21 and 24 km/s along the tail and 4.4 and 2.2 km/s across it, respectively. These measurements set a constraint on an acceleration model of plasma tail and knots as they set the initial speed just after their formation. We also found a rapid narrowing of the tail. After correcting the motion along the tail, the narrowing speed is estimated to be ~ 8 km/s. These rapid motions altogether suggest the need for high time-resolution studies of comet plasma tails with a large telescope.

Yagi, Masafumi; Furusho, Reiko; Terai, Tsuyoshi; Fujiwara, Hideaki; Watanabe, Jun-ichi

2014-01-01

165

Plasma Transition Across the Bow Shock at Saturn: Initial Results From the Cassini Plasma Spectrometer  

NASA Astrophysics Data System (ADS)

The Cassini spacecraft entered the Saturn system in June 2004. The first observation of Saturn's bow shock occurred at 09:48 UT on 27 June 2004 at an absolute distance of 49.2 Rs from the planet. At this time Cassini was approaching Saturn towards dawn, ~30 degrees below the orbital plane with a velocity of ~7.3 kms-1. During this, and six subsequent crossings on the inbound leg, the Cassini plasma spectrometer (CAPS) measured the flux of 0.5 eV to 28.0 keV electrons as they were slowed and heated at the shock front and made some measurements of ions in the downstream region. After the successful insertion burn Cassini encountered the bow shock a further ten times from 82.5 to 87.0 Rs. At this time the orbiter was exiting the Saturn system with a velocity of ~2.6 kms-1 within ~15 degrees of Saturn's equator. During these crossings CAPS was oriented such that the instrument was able to measure the fluxes of 1 eV to 50 keV ions in addition to the electron measurements (which are always available irrespective of spacecraft pointing). The CAPS observations show that the solar wind plasma is strongly modified at the bow shock with electron density enhancements up to a factor of 4 and electron temperature increasing by as much as a factor of ~20. The ion bulk flow in the sheath was typically ~250 kms-1 with a thermal speed of ~100 kms-1. In this presentation we will characterise the plasma transitions observed and compare them with previous studies made by the same instrument at Jupiter. Supporting data from the Cassini magnetometer and the radio and plasma wave instruments will also be presented where appropriate.

Rymer, A. M.; Coates, A. J.; Szego, K.; Bebesi, Z.; Thomsen, M. F.; Gosling, J. T.; Steinberg, J.; McComas, D. J.; Kurth, W. S.; Crary, F. J.

2004-12-01

166

Structure of the plasma fireball produced by a CO2 laser.  

NASA Technical Reports Server (NTRS)

Study of the space and time resolved structure of a helium plasma produced with a repetitive CO2 laser during the first 15 microsec of the afterglow period. The spectra of several neutral and ionized helium lines are used in the determination of the density and temperature profiles of the luminous fireball. It is found that the plasma is comprised of a dense hot core, which emits primarily ionic lines, and a well-defined tenuous outer shell, which is primarily the source of neutral emission lines. This ?two-component' plasma structure develops at about 0.4 microsec after breakdown, at about the time when the luminous fireball dissipates its expansion energy and comes to a virtual standstill.

George, E. V.; Bekefi, G.; Ya'akobi, B.

1971-01-01

167

Plasma-wall interaction studies with optimized laser-produced jets  

NASA Astrophysics Data System (ADS)

The production of the laser-produced plasma jets at burnt-through low-Z foils was optimized by using three-frame interferometry. When striking secondary targets, these jets of energetic particles represent an efficient tool for the investigation of transient phenomena at surfaces of the plasma-exposed solids. Two sets of precisely measured x-ray spectroscopic data demonstrate diagnostic potential of the collimated jets in the plasma-wall interaction studies: Blue Doppler shifts of the Al jet self-emission visualize ion deceleration in the near-wall region. Local depressions found in Al Ly? profiles emitted from Al/Si(PMMA) targets indicate charge exchange between the Al XIII and fully stripped C ions.

Renner, O.; Pisarczyk, T.; Chodukowski, T.; Kalinowska, Z.; Krouský, E.; Pisarczyk, P.; Šmíd, M.; Ullschmied, J.; Dalimier, E.

2011-09-01

168

Application of electrostatic Langmuir probe to atmospheric arc plasmas producing nanostructures  

SciTech Connect

The temporal evolution of a high pressure He arc producing nanotubes was considered and the Langmuir probe technique was applied for plasma parameter measurements. Two modes of arc were observed: cathodic arc where discharge is supported by erosion of cathode material and anodic arc which is supported by ablation of the anode packed with carbon and metallic catalysts in which carbon nanotubes are synthesized. Voltage-current (V-I) characteristics of single probes were measured and unusually low ratio of saturation current on positively biased probe to that on negatively biased of about 1-4 was observed. This effect was explained by increase of measured current at the negatively biased probe above the level of ion saturation current due to secondary electron emission from the probe surface. Since utilization of standard collisionless approach to determine plasma parameters from the measured V-I characteristic is not correct, the electron saturation current was used to estimate the plasma density.

Shashurin, A.; Li, J.; Zhuang, T.; Keidar, M. [Department of Mechanical and Aerospace Engineering, School of Engineering and Applied Science, George Washington University, Washington, District of Columbia 20052 (United States); Beilis, I. I. [School of Electrical Engineering, Tel Aviv University, Ramat Aviv 69978 (Israel)

2011-07-15

169

Application of electrostatic Langmuir probe to atmospheric arc plasmas producing nanostructures  

NASA Astrophysics Data System (ADS)

The temporal evolution of a high pressure He arc producing nanotubes was considered and the Langmuir probe technique was applied for plasma parameter measurements. Two modes of arc were observed: cathodic arc where discharge is supported by erosion of cathode material and anodic arc which is supported by ablation of the anode packed with carbon and metallic catalysts in which carbon nanotubes are synthesized. Voltage-current (V-I) characteristics of single probes were measured and unusually low ratio of saturation current on positively biased probe to that on negatively biased of about 1-4 was observed. This effect was explained by increase of measured current at the negatively biased probe above the level of ion saturation current due to secondary electron emission from the probe surface. Since utilization of standard collisionless approach to determine plasma parameters from the measured V-I characteristic is not correct, the electron saturation current was used to estimate the plasma density.

Shashurin, A.; Li, J.; Zhuang, T.; Keidar, M.; Beilis, I. I.

2011-07-01

170

The reflection of an electromagnetic wave from the self-produced plasma  

SciTech Connect

The dynamic behavior of a high power microwave beam propagating through a gaseous medium, which is ionized in the wave field is investigated. By solving the wave equation, the reflection index of the produced plasma is obtained. It is shown that the cut off condition is different from that of the steady state approximation. The reflection index is less than unity when the plasma density reaches the critical value estimated in the steady state approximation. So, the wave can still propagate through the plasma. By comparing the reflection indexes in the presence and absence of the time delay of the ionization process at different points of the medium, it is shown that it becomes unity much later in the first case. Therefore, the wave propagation takes much more time and consequently the medium is ionized much more.

Mirzaie, M. [Department of Physics, Shahid Beheshti University, G. C., Evin, 1983963113 Tehran (Iran, Islamic Republic of); Shokri, B. [Department of Physics and Laser-Plasma Research Inst., Shahid Beheshti University, G. C., Evin, 1983963113 Tehran (Iran, Islamic Republic of); Rukhadze, A. A. [General Physics Institute, 38-117942 Vavilova St., Moscow (Russian Federation)

2010-01-15

171

High-quality electron beam from laser wake-field acceleration in laser produced plasma plumes  

SciTech Connect

Generation of highly collimated ({theta}{sub div}{approx}10 mrad), quasi-monoenergetic electron beam with peak energy 12 MeV and charge {approx}50 pC has been experimentally demonstrated from self-guided laser wake-field acceleration (LWFA) in a plasma plume produced by laser ablation of solid nylon (C{sub 12}H{sub 22}N{sub 2}O{sub 2}){sub n} target. A 7 TW, 45 fs Ti:sapphire laser system was used for LWFA, and the plasma plume forming pulse was derived from the Nd:YAG pump laser of the same system. The results show that a reproducible, high quality electron beam could be produced from this scheme which is simple, low cost and has the capability for high repetition rate operation.

Sanyasi Rao, Bobbili; Moorti, Anand; Rathore, Ranjana; Ali Chakera, Juzer; Anant Naik, Prasad; Dass Gupta, Parshotam [Laser Plasma Division, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India)] [Laser Plasma Division, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India)

2013-06-10

172

Analysis of the x-ray spectrum emitted by laser-produced plasma of dysprosium  

SciTech Connect

A detailed analysis of the x-ray spectrum (5-10.2 A ring ) emitted by laser-produced plasma of dysprosium (Dy) is given using ab initio calculations with the HULLAC relativistic code and isoelectronic trends. Resonance 3d-4p, 3d-nf (n=4 to 7), 3p-4s, and 3p-4d transitions of Ni I-like Dy XXXIX and neighboring ion satellite transitions (from Dy XXXIV to Dy XL) are identified.

Marcus, Gilad; Louzon, Einat; Henis, Zohar; Maman, Shlomo; Mandelbaum, Pinchas [Soreq Research Center, 81800 Yavne (Israel); Jerusalem College of Engineering, Ramat Beth Hakerem, 91035 Jerusalem (Israel)

2007-05-15

173

Spectra of Mo XXX, XXXI, and XXXII from a laser-produced plasma  

Microsoft Academic Search

Spectra of highly charged Mo ions generated in a laser-produced plasma were observed from 10 to 190 A with a 3 m grazing- incidence spectrograph. Line identifications in Mo XXX-- XXXII were made with the help of relativistic Hartree-Fock calculations. In Mo XXXI (Mg-like) the 3s² ¹Sâ--3s3p ¹P⁠resonance line was found to be at 115.944 A. In Mo XXXII

P. G. Burkhalter; Joseph Reader; Robert D. Cowan

1977-01-01

174

Diagnostic of an expanding laser-produced lithium plasma using ICCD frame photography and shadowgraphy  

Microsoft Academic Search

The expansion of a laser-produced lithium plasma is characterized using two different high-speed imaging techniques. Firstly, a sequence of frames of the luminous plume is recorded using an interference filter\\/gated ICCD camera combination. Expansion velocities are estimated from these images. The conditions, in which the radial distributions of emitters could be recovered using Abel inversion, are discussed. Secondly, shadowgraphs obtained

William Whitty; Jean-Paul Mosnier

1998-01-01

175

Development of a laser-produced-plasma x-ray backlighter for Z  

Microsoft Academic Search

We are in the process of designing and installing a flexible x-ray backlighter on the Z facility at Sandia National Laboratories in Albuquerque, NM. The backlighter system that we are building for Z uses a laser-produced-plasma as the backlighter x-ray source and can be used in either point-projection or area backlighting configurations. The most demanding design criteria of the backlighter

J. L. Porter Jr.; R. G. Adams; J. A. Hands; M. J. Hurst; H. C. Ives; I. L. Martinez; L. E. Ruggles; W. W. Simpson; J. A. Caird; O. L. Landen

1998-01-01

176

PLASMA CELL NEOPLASIA IN A SINGLE HOST: A MOSAIC OF DIFFERENT PROTEIN-PRODUCING CELL TYPES  

PubMed Central

The peritoneal plasma cell neoplasias that develop in strain BALB/c mice after the injection of adjuvant-staphylococcus mixtures or mineral oil alone appear in the form of multiple nodules in the mesentery and on peritoneal surfaces. Experiments were done to determine if these nodules were metastases or multiple primary neoplasms. Nodules or pieces of masses were transplanted subcutaneously by the trochar method or by insertion of tissue under the kidney capsule from 6 primary cases and parallel transplant lines were established. The serum and urinary protein abnormality (a stable heritable characteristic) of each of the various transplant lines was characterized by agar gel electrophoresis and immunoelectrophoresis. Different protein-producing lines were found in 3 cases; in one case 5 different protein-producing lines were isolated. Two different lines were found for each of the other 2 cases. When transplantation studies were begun early, it was demonstrated that the nodules were multiple primary plasma cell neoplasms; when delayed, only one protein-producing plasma cell neoplasm was found. PMID:14488298

Potter, Michael

1962-01-01

177

ELM simulation experiments using transient heat and particle load produced by a magnetized coaxial plasma gun  

NASA Astrophysics Data System (ADS)

It is considered that thermal transient events such as type I edge-localized modes (ELMs) and disruptions will limit the lifetime of plasma-facing components (PFCs) in ITER. It is predicted that the heat load onto the PFCs during type I ELMs in ITER is 0.2-2MJ/m2 with pulse length of ˜0.1-1ms. We have investigated interaction between transient heat and particle load and the PFCs by using a magnetized coaxial plasma gun (MCPG) at University of Hyogo. In the experiment, a pulsed plasma with duration of ˜0.5ms, incident ion energy of ˜30eV, and surface absorbed energy density of ˜0.3-0.7MJ/m2 was produced by the MCPG. However, no melting occurred on a tungsten surface exposed to a single plasma pulse of ˜0.7MJ/m2, while cracks clearly appeared at the edge part of the W surface. Thus, we have recently started to improve the performance of the MCPG in order to investigate melt layer dynamics of a tungsten surface such as vapor cloud formation. In the modified MCPG, the capacitor bank energy for the plasma discharge is increased from 24.5 kJ to 144 kJ. In the preliminary experiments, the plasmoid with duration of ˜0.6 ms, incident ion energy of ˜ 40 eV, and the surface absorbed energy density of ˜2 MJ/m2 was successfully produced at the gun voltage of 6 kV.

Shoda, K.; Sakuma, I.; Iwamoto, D.; Kikuchi, Y.; Fukumoto, N.; Nagata, M.

2011-11-01

178

3-D simulations of magnetic reconnection in high-energy-density laser-produced plasmas  

NASA Astrophysics Data System (ADS)

Magnetic reconnection has recently been observed and studied in high-energy-density, laser-produced plasmas, in a regime characterized by extremely high magnetic fields, high plasma beta and strong, supersonic plasma inflow. These experiments are interesting both for obtaining fundamental data on reconnection, and may also be relevant for inertial fusion, as this magnetic reconnection geometry, with multiple, colliding, magnetized plasma bubbles occurs naturally inside ICF hohlraums. Previous 2-d particle-in-cell reconnection simulations, with parameters and geometry relevant to the experiments, identified key ingredients for obtaining the very fast reconnection rates, namely two-fluid reconnection mediated by collisionless effects (the Hall current and electron pressure tensor), and strong flux pile-up of the inflowing magnetic field [1]. We present results from extending the previous simulations to 3-d, and discuss 3-d effects in the experiments, including instabilities in the reconnection layer, the topological skeleton of null-null lines, and field-generation from the Biermann battery effect. [4pt] [1] W. Fox, A. Bhattacharjee, and K. Germaschewski, PRL 106, 215003 (2011).

Fox, W.; Bhattacharjee, A.; Germaschewski, K.

2012-10-01

179

Nickel plasma produced by 532-nm and 1064-nm pulsed laser ablation  

NASA Astrophysics Data System (ADS)

A comparison between laser ablation of nickel in vacuum by using 532-and 1064-nm Nd:YAG (Yttrium Aluminium Garnet) laser wavelengths, with an intensity of 5 × 109 W/cm2, is reported. Nanosecond pulsed ablation produces high nonisotropic emission of neutrals and ionic species. For 532-nm laser irradiation, mass quadrupole spectrometry, coupled to electrostatic ion deflection and time-of-flight measurements, allows estimation of the energy distributions of the emitted species from plasma. For 1064-nm laser ablation, a cylindrical electrostatic ion analyzer permits one to measure the yield and the charge state of the emitted ions and reconstruct the ion energy and charge state distributions. Neutrals show typical Boltzmann-like distributions, while ions show Coulomb-Boltzmann-shifted distributions depending on their charge state. Surface profiles of the ablated craters permitted study of the ablation threshold and yields of nickel in vacuum versus the laser fluence. The plasma temperature was evaluated using experimental data. Special regard is given to the ion acceleration process occurring inside the plasma due to the high electrical field generated at nonequilibrium plasma conditions and the angular distribution of the emitted species.

Torrisi, L.; Caridi, F.; Margarone, D.; Giuffrida, L.

2008-07-01

180

Kinetic effects and nonlinear heating in intense x-ray-laser-produced carbon plasmas.  

PubMed

The x-ray laser-matter interaction for a low-Z material, carbon, is studied with a particle-in-cell code that solves the photoionization and x-ray transport self-consistently. Photoionization is the dominant absorption mechanism and nonthermal photoelectrons are produced with energy near the x-ray photon energy. The photoelectrons ionize the target rapidly via collisional impact ionization and field ionization, producing a hot plasma column behind the laser pulse. The radial size of the heated region becomes larger than the laser spot size due to the kinetic nature of the photoelectrons. The plasma can have a temperature of more than 10 000 K (>1eV), an energy density greater than 10^{4} J/cm^{3}, an ion-ion Coulomb coupling parameter ??1, and electron degeneracy ??1, i.e., strongly coupled warm dense matter. By increasing the laser intensity, the plasma temperature rises nonlinearly from tens of eV to hundreds of eV, bringing it into the high energy density matter regime. The heating depth and temperature are also controllable by changing the photon energy of the incident laser light. PMID:25493733

Sentoku, Y; Paraschiv, I; Royle, R; Mancini, R C; Johzaki, T

2014-11-01

181

Light scattering measurements with Titan's aerosols analogues produced by dusty plasma  

NASA Astrophysics Data System (ADS)

The Titan s atmosphere contains solid aerosols produced by the photochemistry of nitrogen and methane These aerosols are at the origin of the characteristic brown yellow colour of Titan During the descent of the Huygens probe the 14 th January 2005 optical measurements of the Titan s haze and Titan s surface have been done In order to explain the obtained results laboratory simulations are necessary We produce analogues of the Titan s aerosols in a RF capacitively coupled low-pressure plasma in a N 2 --CH 4 mixture representative of the Titan s atmosphere Szopa et al 2006 Szopa et al this conference The morphology of the produced solid aerosols is observed by SEM analyses They are quasi spherical and their mean size is function of the plasma conditions Moreover their colour changes from yellow to brown as a function of CH 4 ratio in the plasma In order to have information on the optical properties of the produced aerosols measurements have been performed with the PROGRA2 experiment Renard et al 2002 The PROGRA2 experiment measures the phase dependence of the linear polarization of the light scattered by dust particles for two wavelengths 543 5 nm and 632 8 nm The particles are lifted either in microgravity in the CNES ESA dedicated airplane or by an air-draught in ground-based conditions The aim of this work is to build a database for further modelling of the optical properties of Titan s in connection with the Huygens data These particles have also an astrophysical interest as organic compounds Hadamcik et

Hadamcik, E.; Renard, J.-B.; Szopa, C.; Cernogora, G.; Levasseur-Regourd, A. C.

182

Estimation of the initial amplitude of perturbation and its use in numerical simulation of plasma bubbles  

NASA Astrophysics Data System (ADS)

This work describes an experimental method for the calculation of the initial amplitude of plasma bubble seed perturbation in the bottomside F layer from ionograms. The observations show that after sunset the ionograms exhibit irregularities in the base of the F trace. In the context of the plasma depletion in the bottomside F-layer, the irregularities in ionograms can be seen like isodensity contour in evolution (in space and time). The initial amplitudes, calculated using the methodology, were used to simulate plasma bubbles through the use of flux corrected transport method with Boris-Book's flux limiter for the spatial integration and a predictor-corrector method for the direct time integration of the continuity equation of {O}^{+} and the SOR method for electric potential equation. Generalized Rayleigh-Taylor instability plays a predominant role in the evolution of long-wavelength irregularities in the equatorial ionosphere. This instability is influenced by the vertical density gradient at bottom of the F layer, and the magnitude and shape of the density perturbation that seeds the instability. The code is tested with different enhanced evening eastward electric fields to study the influences of pre-reversal enhancement in the zonal electric field on plasma bubble formation and development. The values of the zonal electric fields are based on Digisonde observations over the dip equatorial station of Cachimbo (9.5° S, 54.8° W) during the 2002 COPEX (Conjugate Point Equatorial Experiment) campaign in Brazil.

Batista, Inez S.; Carrasco, Alexander J.; Abdu, Mangalathayil A.

2012-07-01

183

Study of nanosecond laser-produced plasmas in atmosphere by spatially resolved optical emission spectroscopy  

SciTech Connect

We investigate the evolution of the species from both the target and the air, and the plasma parameter distribution of the nanosecond laser-produced plasmas in atmospheric air. The technique used is spatially resolved optical emission spectroscopy. It is argued that the N II from the air, which is distributed over a wider region than the target species in the early stages of the discharge, is primarily formed by the shock wave. The ionized species have a larger expansion velocity than the excited atoms in the first ?100 ns, providing direct evidence for space-charge effects. The electron density decreases with the distance from the target surface in the early stages of the discharge, and both the electron density and the excited temperature variation in the axial direction are found to become insignificant at later stages.

Wei, Wenfu; Wu, Jian; Li, Xingwen; Jia, Shenli; Qiu, Aici [State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, No. 28 XianNing West Road, Xi'an, Shaanxi Province 710049 (China)] [State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, No. 28 XianNing West Road, Xi'an, Shaanxi Province 710049 (China)

2013-09-21

184

Spectroscopic study of emission coal mineral plasma produced by laser ablation  

NASA Astrophysics Data System (ADS)

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 C2 Swan System (d3?g?a3?u), the First Negative System N2 (Band head at 501,53 nm) and emission lines of the C I, C II, were investigated using the optical emission spectroscopy technique. The C2 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 x1018 cm-3 respectively.

Vera, L. P.; Pérez, J. A.; Riascos, H.

2014-05-01

185

Properties of surface layers on titanium alloys produced by plasma carboxynitriding process  

SciTech Connect

The recent rapid progress in technique requires that the titanium alloys should have better resistance to frictional wear and to the action of corrosive agents. These requirements can be satisfied by producing surface layers of specified microstructure and phase composition. The present paper describes a modification of the plasma discharge nitriding treatment of titanium alloys, i.e., the glow discharge assisted oxycarbonitriding, which by introducing oxygen, nitrogen and carbon into the surface zone of the layer (a TI(NCO) type layer) improves its useful properties, primarily the resistance to frictional wear and the resistance to corrosion. This is so since titanium shows a good affinity to oxygen, carbon and nitrogen, whereas the chemical composition of the layer depends on the chemical composition of the low-temperature plasma that forms under the conditions of glow discharge.

Wierzchon, T.; Fleszar, A.; Krupaand, D.; Narbutta, L. [Warsaw Univ. of Technology (Poland)

1995-12-31

186

Development of a time-resolved soft x-ray spectrometer for laser produced plasma experiments  

SciTech Connect

A 2400 lines/mm variable-spaced grating spectrometer has been used to measure soft x-ray emission (8-22 A) from laser-produced plasma experiments at Lawrence Livermore National Laboratory's Compact Multipulse Terrawatt (COMET) Laser Facility. The spectrometer was coupled to a Kentech x-ray streak camera to study the temporal evolution of soft x rays emitted from the back of the Mylar and the copper foils irradiated at 10{sup 15} W/cm{sup 2}. The instrument demonstrated a resolving power of {approx}120 at 19 A with a time resolution of 31 ps. The time-resolved copper emission spectrum was consistent with a photodiode monitoring the laser temporal pulse shape and indicated that the soft x-ray emission follows the laser heating of the target. The time and spectral resolutions of this diagnostic make it useful for studies of high temperature plasmas.

Cone, K. V.; Park, J. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); University of California at Davis, Davis, California 95616 (United States); Dunn, J.; Schneider, M. B.; Brown, G. V.; Emig, J.; James, D. L.; May, M. J.; Shepherd, R.; Widmann, K. [Lawrence Livermore National Laboratory, Livermore, California 94551 (United States); Baldis, H. A. [University of California at Davis, Davis, California 95616 (United States)

2010-10-15

187

Diagnostic of an expanding laser-produced lithium plasma using ICCD frame photography and shadowgraphy  

NASA Astrophysics Data System (ADS)

The expansion of a laser-produced lithium plasma is characterized using two different high-speed imaging techniques. Firstly, a sequence of frames of the luminous plume is recorded using an interference filter/gated ICCD camera combination. Expansion velocities are estimated from these images. The conditions, in which the radial distributions of emitters could be recovered using Abel inversion, are discussed. Secondly, shadowgraphs obtained with a synchronized tunable dye laser light source are recorded at different probe wavelengths in the vicinity of the Li 0 670.7-nm resonance. The fringe patterns observed in these images are interpreted in terms of strong refractive index gradients within the plasma. The effect of anomalous dispersion is observed and strongly modifies the appearance of the shadowgraphs.

Whitty, William; Mosnier, Jean-Paul

1998-05-01

188

Behavior of porosity and copper oxidation in W/Cu composite produced by plasma spray  

NASA Astrophysics Data System (ADS)

A spherical tungsten (W)/copper (Cu) composite powder was plasma-sprayed onto a boron-nitride-coated graphite substrate to produce heat sink material for the electronic packaging by atmospheric plasma spray using different input powers. At the surface of the deposited layer, Cu became oxidized to cuprite (Cu2O). The degree of oxidation at the surface layer did not vary significantly with input power. Very little Cu2O was detected at the inner layers after grinding off the 70 µm from the surface. The input powers had a strong effect on the porosity in the deposit layers. The porosity in the deposit layers at 25 kW was very small, about 3 vol%. The microstructures of W/Cu composite were discussed.

Kang, Hyun-Ki; Kang, Suk Bong

2004-06-01

189

Development of a Time-resolved Soft X-ray Spectrometer for Laser Produced Plasma Experiments  

SciTech Connect

A 2400 line/mm variable spaced grating spectrometer (VSG) has been used to measure soft x-ray emission (8-22 {angstrom}) from laser-produced plasma experiments at Lawrence Livermore National Laboratory's Compact Multipulse Terrawatt (COMET) Laser Facility. The spectrometer was coupled to a Kentech x-ray streak camera to study the temporal evolution of soft x-rays emitted from the back of mylar and copper foils irradiated at 10{sup 15} W/cm{sup 2}. The instrument demonstrated a resolving power of {approx} 120 at 19 {angstrom} with a time resolution of 31 ps. The time-resolved copper emission spectrum was consistent with a photodiode monitoring the laser temporal pulse shape and indicated that the soft x-ray emission follows the laser heating of the target. The time and spectral resolution of this diagnostic make it useful for studies of high temperature plasmas.

Cone, K V; Dunn, J; Schneider, M B; Baldis, H A; Brown, G V; Emig, J; James, D L; May, M J; Park, J; Shepherd, R; Widmann, K

2010-05-12

190

Investigation of nanoparticle formation in a plasma produced by femtosecond laser ablation of gold  

SciTech Connect

The formation of nanoparticles in a plasma produced by the interaction of ultrashort laser pulses with gold has been investigated. Three different experimental techniques were employed. (i) The plume expansion was characterized using fast imaging with the aid of an intensified charge-coupled device. (ii) The plasma composition was analyzed using time- and space-resolved optical emission spectroscopy. (iii) The ablated material was deposited on mica substrates and analyzed by means of atomic force microscopy. As a result, the size-distribution and the overall number of nanoparticles were determined as a function of the laser energy density incident on the target surface. The detection of particles with sizes in the nanometer range supports theoretical modeling according to which phase explosion is the dominant mechanism of metal ablation by ultrashort laser pulses.

Spiga, P.; Hermann, J.; Itina, T.; Grojo, D. [LP3, UMR 6182 CNRS-Faculte des Sciences de Luminy, Case 917, F-13288 Marseille (France); Neamtu, D. [NILPRP- Laser Department, P.O. Box MG-36, R-76900 Bucharest (Romania); Pailharey, D.; Marine, W. [CRMCN, UPR CNRS 7251-Faculte des Sciences de Luminy, Case 901, F-13288 Marseille (France)

2005-10-31

191

Extreme ultraviolet spectra from highly charged gadolinium and neodymium ions in the Large Helical Device and laser produced plasmas  

NASA Astrophysics Data System (ADS)

We have observed extreme ultraviolet spectra from highly charged gadolinium (Gd) and neodymium (Nd) ions produced in two different types of light sources for comparative studies. Only broad quasicontinuum feature arising from unresolved transition array was observed in high-density laser produced plasmas of pure/diluted Gd and Nd targets at the University College Dublin, and the spectral feature largely depends on electron temperature in optically thin plasmas produced in the Large Helical Device at the National Institute for Fusion Science. The difference in spectral feature among a number of spectra can be qualitatively interpreted by considering dominant ion stages and opacity effects in the plasmas.

Suzuki, C.; Koike, F.; Murakami, I.; Tamura, N.; Sudo, S.; O'Gorman, C.; Li, B.; Harte, C. S.; Donnelly, T.; O'Sullivan, G.

2013-09-01

192

Production of geopolymers using glass produced from DC plasma treatment of air pollution control (APC) residues.  

PubMed

Air pollution control (APC) residues are the hazardous waste produced from cleaning gaseous emissions at energy-from-waste (EfW) facilities processing municipal solid waste (MSW). APC residues have been blended with glass-forming additives and treated using DC plasma technology to produce a high calcium alumino-silicate glass. This research has investigated the optimisation and properties of geopolymers prepared from this glass. Work has shown that high strength geopolymers can be formed and that the NaOH concentration of the activating solution significantly affects the properties. The broad particle size distribution of the APC residue glass used in these experiments results in a microstructure that contains unreacted glass particles included within a geopolymer binder phase. The high calcium content of APC residues may cause the formation of some amorphous calcium silicate hydrate (C-S-H) gel. A mix prepared with S/L=3.4, Si/Al=2.6 and [NaOH]=6M in the activating solution, produced high strength geopolymers with compressive strengths of approximately 130 MPa. This material had high density (2070 kg/m(3)) and low porosity. The research demonstrates for the first time that glass derived from DC plasma treatment of APC residues can be used to form high strength geopolymer-glass composites that have potential for use in a range of applications. PMID:20022170

Kourti, Ioanna; Rani, D Amutha; Deegan, D; Boccaccini, A R; Cheeseman, C R

2010-04-15

193

On the microstructural and magnetic properties of fine-grained CoFe2O4 ceramics produced by combining polyol process and spark plasma sintering  

NASA Astrophysics Data System (ADS)

Starting from polyol-made CoFe2O4 ferrite nanoparticles of different aggregation states, high-density fine-grained ceramics were produced using Spark Plasma Sintering technique at 600 and 500 °C, under vacuum and applying a uniaxial pressure of more than 80 MPa. The grain growth of thus produced ceramics appears to be proportional to the temperature plateau and inversely proportional to the aggregation state of the initial powders. Average grain sizes ranging between about 50 and 350 nm were obtained. In all the cases, magnetic measurements evidenced a ferrimagnetic behavior at room temperature with non-zero coercivity, while their starting powders exhibited superparamagnetic features.

Gaudisson, T.; Artus, M.; Acevedo, U.; Herbst, F.; Nowak, S.; Valenzuela, R.; Ammar, S.

2014-12-01

194

SiC/C nanocable structure produced in silicon carbide by arc plasma heating  

NASA Astrophysics Data System (ADS)

Defect-free and long SiC/C nanocables have been produced by heating SiC powder at 3000°C by employing dc arc plasma (Ar) in a specially designed configuration of graphite arc. Microstructural characterizations of the heat-treated powder carried out by TEM, HRTEM, SAED, EDS, and micro Raman spectroscopy showed the nanocables to consist of a SiC shell/sheath stuffed with wire type solid C core. A possible mechanism is discussed to explain the cable-type growth.

Nayak, B. B.

2012-01-01

195

[Aspergillus ochraceus myxomycetes produce extracellular proteinases--protein C activators of blood plasma].  

PubMed

Natural isolates of Aspergillus ochraceus myxomycetes from soil and plant remains from various regions have been screened. The isolated strains were characterized by similar cultural and morphological features and an identical nucleotide sequence in the ITS1-5,8S-ITS2 region of rDNA. The ability of the extracellular proteinases of A. ochraceus myxomycetes to activate protein C of blood plasma has been established. Differences are revealed in the accumulation of proteinases activating protein C and proteinases with thrombin- and plasmin-like activities in the growth dynamics of producers. PMID:23101392

Osmolovski?, A A; Kre?er, V G; Kurakov, A V; Baranova, N A; Egorov, N S

2012-01-01

196

Temporal and spatial evolution of Si atoms in plasmas produced by a nanosecond laser ablating silicon carbide crystals.  

PubMed

Optical emission spectroscopy (OES) was used to study the evolution behavior of the neutral Si atoms in the plasma produced by nanosecond pulsed-laser beam irradiating on SiC crystal targets. The OES measurements indicated that the electron temperature and density in the plasma had maximum values around a region about 2mm from the target surface. Based on the temporal and spatial evolution of the spectral line at 633.19 nm originating from excited Si atoms, it was found that these Si atoms have short decay times and long range spatial distribution in vacuum. At the initial growth stage of SiC thin films using pulsed-laser deposition (PLD) technique, these Si atoms were found possibly to arrive at the Si substrate to form defects near the SiC/Si interface. By comparing the OES result measured in vacuum and that measured in ambient air, it was deduced that by properly adjusting the background gas species and pressure, the quality of the films prepared by PLD technique may be improved. PMID:19658821

Chen, Ming; Liu, Xiangdong; Zhao, Mingwen; Chen, Chuansong; Man, Baoyuan

2009-07-01

197

Generation of metal ions in the beam plasma produced by a forevacuum-pressure electron beam source  

NASA Astrophysics Data System (ADS)

We report on the production of metal ions of magnesium and zinc in the beam plasma formed by a forevacuum-pressure electron source. Magnesium and zinc vapor were generated by electron beam evaporation from a crucible and subsequently ionized by electron impact from the e-beam itself. Both gaseous and metallic plasmas were separately produced and characterized using a modified RGA-100 quadrupole mass-spectrometer. The fractional composition of metal isotopes in the plasma corresponds to their fractional natural abundance.

Tyunkov, A. V.; Yushkov, Yu. G.; Zolotukhin, D. B.; Savkin, K. P.; Klimov, A. S.

2014-12-01

198

Initial reaction of hafnium oxide deposited by remote plasma atomic layer deposition method  

SciTech Connect

A remote plasma atomic layer deposition (RPALD) method has been applied to grow a hafnium oxide thin film on the Si substrate. The deposition process was monitored by in situ XPS and the as-deposited structure and chemical bonding were examined by TEM and XPS. The in situ XPS measurement showed the presence of a hafnium silicate phase at the initial stage of the RPALD process up to the 20th cycle and indicated that no hafnium silicide was formed. The initial hafnium silicate was amorphous and grew to a thickness of approximately 2 nm. Based on these results and model reactions for silicate formation, we proposed an initial growth mechanism that includes adatom migration at nascent step edges. Density functional theory calculations on model compounds indicate that the hafnium silicate is thermodynamically favored over the hafnium silicide by as much as 250 kJ/mol.

Won, Youngdo; Park, Sangwook; Koo, Jaehyoung; Kim, Seokhoon; Kim, Jinwoo; Jeon, Hyeongtag [Department of Chemistry, Hanyang University, Seoul 133-791 (Korea, Republic of); Division of Materials Science and Engineering, Hanyang University, Seoul 133-791 (Korea, Republic of)

2005-12-26

199

Soft-x-ray amplification in a laser-produced strontium plasma  

SciTech Connect

Amplification of soft x rays in Sr ({ital Z}=38) plasmas produced by second-harmonic laser irradiation of exploding foil targets is studied. Gains of 4.4 and 4.0 cm{sup {minus}1}, respectively, have been measured for the 164.1- and 166.5-A {ital J}=2 to 1 transitions in Ne-like Sr at laser intensities of 1.3{times}10{sup 14} W/cm{sup 2}. Numerous x-ray and soft-x-ray transitions were identified in order to demonstrate typical spectra from x-ray laser plasmas and infer information regarding the plasma ionization balance. The {ital J}=0 to 1 transition at 159.8 A, analogous to the well-known Se {ital J}=0 to 1 line at 182.4 A, was not definitively observed due to a wavelength overlap with a Na-like Sr line. Two other {ital J}=0 to 1 transitions of interest at 84.9 and 133.0 A were not observed. Reduced gain on the {ital J}=2 to 1 lasing lines was seen for several shots taken at a lower pump laser intensity of 7.0{times}10{sup 13} W/cm{sup 2}. Possible reasons for this are considered. The results of this work imply the feasibility of a high-output-power cavity geometry Ne-like Sr x-ray laser operating at 164.1 and 166.5 A.

Keane, C.J.; Matthews, D.L.; Rosen, M.D.; Phillips, T.W.; MacGowan, B.J.; Whitten, B.L. (Lawrence Livermore National Laboratory, University of California, Livermore, CA (USA)); Louis-Jacquet, M.; Bourgade, J.L.; DeCoster, A.; Jacquemot, S.; Naccache, D.; Thiell, G. (Centre d'Etudes de Limeil-Valenton, Villeneuve, St. Georges (France))

1990-08-15

200

Temporal and spatial dynamics of a laser-produced plasma through a multiple Langmuir probe detector  

NASA Astrophysics Data System (ADS)

At the Laboratory for Energy Conversion (LEC), ETH Zurich, droplet-based LPP-EUV light sources have been developed since 2007. The main LPP source is ALPS II, which is fully operational since more than one year. The facility is an engineering test stand for long-term effect studies. In order to improve the debris mitigation techniques, it is essential to investigate the droplet plasma dynamics in time and space. Recently a new diagnostic tool based on a multiple array of motorized Langmuir probes has been constructed for this purpose. The detector has been used to map the angular and radial distribution of the ion and electron dynamics around the droplet target. In this paper, some of the experimental results obtained with the new detector are reported. The angular and radial distribution of the ion flux and kinetic energy of the droplet plasma reveals an anisotropic expansion of the ions in terms of kinetic energy and amount of ion charge around the droplet target. These results have been obtained during continuous source operation and for the first time on droplet-based laser produced plasmas.

Gambino, Nadia; Brandstätter, Markus; Rollinger, Bob; Abhari, Reza S.

2014-04-01

201

Ion flux enhancements and oscillations in spatially confined laser produced aluminum plasmas  

NASA Astrophysics Data System (ADS)

Ion signals from laser produced plasmas (LPPs) generated inside aluminum rectangular cavities at a fixed depth d = 2 mm and varying width, x = 1.0, 1.6, and 2.75 mm were obtained by spatially varying the position of a negatively biased Langmuir probe. Damped oscillatory features superimposed on Maxwellian distributed ion signals were observed. Depending on the distance of the probe from the target surface, three to twelve fold enhancements in peak ion density were observed via confinement of the LPP, generated within rectangular cavities of varying width which constrained the plasma plume to near one dimensional expansion in the vertical plane. The effects of lateral spatial confinement on the expansion velocity of the LPP plume front, the temperature, density and expansion velocity of ions, enhancement of ion flux, and ion energy distribution were recorded. The periodic behavior of ion signals was analyzed and found to be related to the electron plasma frequency and electron-ion collision frequency. The effects of confinement and enhancement of various ion parameters and expansion velocities of the LPP ion plume are explained on the basis of shock wave theory.

Singh, S. C.; Fallon, C.; Hayden, P.; Mujawar, M.; Yeates, P.; Costello, J. T.

2014-09-01

202

Vacuum laser-initiated plasma shutters for retropulse isolation in Antares  

SciTech Connect

We have demonstrated that sintered LiF spatial filters may be used in a 10/sup -6/-torr vacuum environment as laser-initiated plasma shutters for retropulse isolation in the Antares high-energy laser fusion system. In our experiments, a 1.1-ns pulsed CO/sub 2/ laser, at a 10-..mu..m wavelength and an energy of up to 3.0 J, was used for plasma initiation; a chopped probe laser tuned to a 9l6-..mu..m wavelength was used in determining the blocking time of the plasma. We measured the 10.6- and 9.6-..mu..m beam transmissions as a function of fluence on the aperture edge. For an 800-..mu..m-diam aperture and a 1.2-mm-diam Gaussian beam determined at the 1/e/sup 2/ intensity points, we observed blocking times in excess of 1.0 ..mu..s.

Sheheen, T.W.; Czuchlewski, S.J.; Hyde, J.; Ainsworth, R.L.

1983-03-01

203

Radiative properties of Z-pinch and laser produced plasmas from mid-atomic-number materials  

NASA Astrophysics Data System (ADS)

The investigation of Z-pinches on university-scale pulsed power generators allows for the study of plasmas with a broad range of temperatures, densities, and sizes in cost effective experiments. In particular, X-pinches produce the hottest and densest plasma and are very suitable for x-ray radiation studies. The planar wire array has shown to be a powerful radiation source on the 1 MA Zebra generator at UNR. The radiative and implosion dynamics from such loads with mid-atomic-number materials were not studied previously in detail and are a topic of this dissertation. Specifically, the radiative and implosion characteristics of Z-pinch and X-pinch plasmas with mid-atomic-number materials (iron, nickel, copper, and zinc) will be discussed. The theoretical tool used to accomplish this is non-LTE kinetic modeling. This tool is not limited to Z-pinches, but can be applied to any plasma radiation source like laser produced plasmas which will be demonstrated. In addition, since the radiative characteristics of wire arrays are connected with the implosion characteristics, another theoretical tool, the Wire Ablation Dynamics Model was used in this dissertation to understand the ablation and implosion dynamics of wire arrays. The experiments were analyzed from two university-scale pulsed power machines: the 1 MA Zebra and COBRA generators. The research completed in this dissertation emphasizes the unique capabilities and usefulness of spectroscopy, particularly time-gated x-ray spectroscopy. For example, modeling of time-gated L-shell spectra captured from the precursor column of low-wire-number copper cylindrical wire arrays reveals electron temperatures ˜400 eV, which is significantly higher than any previous precursor measurements. From the analysis of experiments on COBRA, total energy was higher for the implosion of a compact cylindrical wire array made with alternating brass and aluminum wires than a uniform wire array made with just brass or aluminum. Comparison of L-shell radiation from mid-atomic-number wires placed in the inner or outer array from nested wire array implosions on COBRA shows that the material radiates more when placed on the outer array. Using different materials on the outer and inner arrays provides a unique opportunity to study the implosion dynamics of nested wire arrays, especially when using time-gated spectroscopy. Brass planar wire arrays represent a unique opportunity to study the performance of two L-shell radiators from mid-atomic-number materials (copper and zinc) at the same time in experiments on Zebra. The ablation and implosion dynamics of the single- and double-planar wire arrays was investigated and completed. Non-LTE kinetic modeling was used to describe the radiation from simultaneous measurements of K- and L-shell radiation from the interaction of a femtosecond laser system with an iron target. The K- and L-shell radiation originates from two distinct plasma regions. The L-shell radiation was emitted from a region of plasma created by the prepulse and modeling showed moderate electron temperatures and electron densities. The cold iron Kalpha line manifested from a region of plasma that was heated by hot electrons interacting with the solid dense iron target. K-shell modeling showed electron temperatures of tens of eV and less than 1% hot electrons. To study the time history of cold Kalpha lines for mid-atomic-number materials, experiments with planar wire arrays were performed on Zebra. Continuation of this study was accomplished using X-pinches to allow for the simultaneous measurements in time of hotter ionic and cold K-shell lines.

Ouart, Nicholas D.

204

Identification of hydrogenlike and heliumlike transitions in the spectrum of laser-produced magnesium plasmas  

NASA Technical Reports Server (NTRS)

Nonresonance spectral lines of Mg XII and Mg XI emitted by magnesium laser-produced plasmas have been observed in the extreme-vacuum-ultraviolet region and their transitions classified. As many as eight beams of the Omega laser system of the Laboratory for Laser Energetics at the University of Rochester were linearly focused onto magnesium-coated flat targets to produce linear plasma radiation sources from 3 to 6 mm long. The spectra were photographed end-on with a grazing-incidence spectrograph. The identified Mg XII lines are classified as 2s-3p, 2p-3d, 2s-4p, 2p-4d, and 3d-4f transitions. The identified Mg XI lines are classified as 1s2s-1s3p, 1s2p-1s3d, 1s2p-1s4d, 1s3p-1s4d, and 1s3d-1s4f.

Moreno, J. C.; Goldsmith, S.; Griem, H. R.; Cohen, Leonard; Knauer, J.

1990-01-01

205

Time of flight emission spectroscopy of laser produced nickel plasma: Short-pulse and ultrafast excitations  

NASA Astrophysics Data System (ADS)

We report the experimental investigation and comparison of the temporal features of short-pulse (7 ns) and ultrafast (100 fs) laser produced plasmas generated from a solid nickel target, expanding into a nitrogen background. When the ambient pressure is varied in a large range of 10-6 Torr to 102 Torr, the plume intensity is found to increase rapidly as the pressure crosses 1 Torr. Time of flight (TOF) spectroscopy of emission from neutral nickel (Ni I) at 361.9 nm (3d9(2D) 4p ? 3d9(2D) 4s transition) reveals two peaks (fast and slow species) in short-pulse excitation and a single peak in ultrafast excitation. The fast and slow peaks represent recombined neutrals and un-ionized neutrals, respectively. TOF emission from singly ionized nickel (Ni II) studied using the 428.5 nm (3p63d8(3P) 4s? 3p63d9 4s) transition shows only a single peak for either excitation. Velocities of the neutral and ionic species are determined from TOF measurements carried out at different positions (i.e., at distances of 2 mm and 4 mm, respectively, from the target surface) on the plume axis. Measured velocities indicate acceleration of neutrals and ions, which is caused by the Coulomb pull of the electrons enveloping the plume front in the case of ultrafast excitation. Both Coulomb pull and laser-plasma interaction contribute to the acceleration in the case of short-pulse excitation. These investigations provide new information on the pressure dependent temporal behavior of nickel plasmas produced by short-pulse and ultrafast laser pulses, which have potential uses in applications such as pulsed laser deposition and laser-induced nanoparticle generation.

Smijesh, N.; Chandrasekharan, K.; Joshi, Jagdish C.; Philip, Reji

2014-07-01

206

Diamond-like carbon produced by plasma source ion implantation as a corrosion barrier  

SciTech Connect

There currently exists a broad range of applications for which the ability to produce an adherent, hard, wear and, corrosion-resistant coating plays a vital role. These applications include engine components, orthopedic devices, textile manufacturing components, hard disk media, optical coatings, and cutting and machining tools (e.g., punches, taps, scoring dies, and extrusion dies). Ion beam processing can play an important role in all of these technologies. Plasma source ion implantation (PSII) is an emerging technology which has the potential to overcome the limitations of conventional ion implantation by: (1) reducing the time and expense for implanting onto complex shapes and large areas and (2) extending the thickness of the modification zone through ion beam enhanced plasma growth of surface coatings. In PSII, targets are placed directly in a plasma source and then pulse biased to produce a non-line-of-sight process for complex-shaped targets without complex fixturing. If the pulse bias is a relatively high negative potential (20 to 100 kV) ion implantation will result. If however, a low voltage (50--1,200 eV) high duty cycle pulse bias is applied, film deposition from the chamber gas will result, thereby increasing the extent of the surface modification into the 1--10 micron regime. To evaluate the potential for DLC to be used as a corrosion barrier, Electrochemical Impedance Spectroscopy (EIS) and traditional electrochemistry techniques were used to investigate the breakdown mechanism in chloride and nonchloride containing environments. The effect of surface preparation on coating breakdown was also evaluated.

Lillard, R.S.; Butt, D.P.; Taylor, T.N.; Walter, K.C.; Nastasi, M.

1998-03-01

207

High-order harmonic generation during propagation of femtosecond pulses through the laser-produced plasmas of semiconductors  

NASA Astrophysics Data System (ADS)

The generation of high-order harmonics of the ultrashort pulses of Ti:sapphire laser in the plasma plumes produced during laser ablation of various semiconductors (Te, Se, Si, As, Sb, and Ge) is reported. Application of two-color pump allowed the generation of enhanced odd and even harmonics. The resonance-induced enhancement of single harmonics was observed in the Ge, Se, Sb, As, and Te plasmas. The enhanced 35th harmonic obtained from selenium plasma was twelve times stronger than the neighboring harmonics. We also demonstrate the quasi-phase-matching of the harmonics generated in the As plasma.

Ganeev, R. A.; Suzuki, M.; Yoneya, S.; Kuroda, H.

2015-01-01

208

Enhancing extreme ultraviolet photons emission in laser produced plasmas for advanced lithography  

SciTech Connect

Current challenges in the development of efficient laser produced plasma sources for the next generation extreme ultraviolet lithography (EUVL) are increasing EUV power and maximizing lifetime and therefore, reducing cost of devices. Mass-limited targets such as small tin droplets are considered among the best choices for cleaner operation of the optical system because of lower mass of atomic debris produced by the laser beam. The small diameter of droplets, however, decreases the conversion efficiency (CE) of EUV photons emission, especially in the case of CO{sub 2} laser, where laser wavelength has high reflectivity from the tin surface. We investigated ways of improving CE in mass-limited targets. We considered in our modeling various possible target phases and lasers configurations: from solid/liquid droplets subjected to laser beam energy with different intensities and laser wavelength to dual-beam lasers, i.e., a pre-pulse followed by a main pulse with adjusted delay time in between. We studied the dependence of vapor expansion rate, which can be produced as a result of droplet heating by pre-pulse laser energy, on target configuration, size, and laser beam parameters. As a consequence, we studied the influence of these conditions and parameters on the CE and debris mass accumulation. For better understanding and more accurate modeling of all physical processes occurred during various phases of laser beam/target interactions, plasma plume formation and evolution, EUV photons emission and collection, we have implemented in our heights package state-of-the art models and methods, verified, and benchmarked against laboratory experiments in our CMUXE center as well as various worldwide experimental results.

Sizyuk, T.; Hassanein, A. [Center for Materials under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)

2012-08-15

209

The Ulysses solar wind plasma investigation: Description and initial in-ecliptic results  

SciTech Connect

During the in-ecliptic flight of Ulysses from the Earth toward its encounter with Jupiter, the Los Alamos solar wind plasma experiment has performed well. Briefly described, the instrumentation contains two independent electrostatic analyzers, one for ions and one for electrons. Initial analysis of solar wind electron core temperatures obtained between 1.15 and 3.76 AU yields a gradient of T {proportional to} R{sup {minus}0.7} which is flatter than expected for adiabatic expansion of a single-temperature Maxwellian velocity distribution and steeper than that obtained from Mariner-Voyager.

Bame, S.J.; Phillips, J.L.; McComas, D.J.; Gosling, J.T. (Los Alamos National Lab., NM (United States)); Goldstein, B.E. (Jet Propulsion Lab., Pasadena, CA (United States))

1991-01-01

210

Optimization of laser-produced plasmas for nanolithography and materials detection  

NASA Astrophysics Data System (ADS)

In this work, laser-matter interactions and resultant plasma emission using traditional short pulsed lasers are studied in the context of semiconductor lithography and material sensing applications. Ultrafast laser ablation and plasma emission results are then compared to those using traditional short pulsed lasers. Then fundamental laser-matter interactions and ablation processes of ultrafast lasers are investigated. This work focuses on laser-produced plasma (LPP) light sources at extreme ultraviolet (EUV) wavelengths. The out-of-band (OoB) light emission as well as ionic and atomic debris from the plasma source, which are capable of damaging collection optics, have been studied as a function of incident laser wavelength to characterize the angular distributions of debris and identify the differences in debris from longer and shorter laser excitation wavelengths. By applying a prepulse to create improved laser-target coupling conditions, conversion efficiency (CE) from laser energy to 13.5 nm light emission from the plasma source can be improved by 30% or higher. Energetic ions escaping from the plasma can cause significant damage to light collection optics, greatly reducing their lifetimes, but by implementing a prepulse, it has been shown that most-probable ion energies can be reduced significantly, minimizing damage caused to collection optics. Laser-induced breakdown spectroscopy (LIBS) is a technique used to identify the elemental constituents of unknown samples by studying the optical light spectra emitted from a LPP. Despite advantages such as in situ capabilities and near-instant results, detection limits of LIBS systems are not as competitive as other laboratory-based systems. To overcome such limitations, a double pulse (DP) LIBS system is arranged using a long-wavelength laser for the second pulse and heating of the plume created by the first pulse. Detector gating parameters were optimized and different first-pulse laser energies were investigated to study improvements with increasing mass ablation. The long-wavelength laser does not increase mass ablation in DP-LIBS and through optimization, it is found that maximum enhancements are observed for cases of smallest mass ablation; an important consideration for analysis of delicate samples. For bulk element analysis, enhancements of 14 and 10 times for S/N and S/B, respectively, are seen, and for trace element analysis, enhancements of 7 and 3 times for S/N and S/B, respectively, are seen. Due to extremely short pulse durations, the ablation mechanisms for ultrafast lasers are not fully understood, meaning their implementation in existing and novel laser applications are hindered. The differences in visible emission dynamics from nanosecond (ns) and femtosecond (fs) laser ablation (LA) plumes are reported and the effects that vacuum and ambient pressure environments play on plasma plume expansion dynamics. Lastly, a fundamental study of ultrafast laser ablation is performed to better understand ablation mechanisms and resultant plasma plume properties. Under ns laser ablation, ion time of flight analysis typically shows a single-peak profile, however, under fs laser ablation a double-peak profile is observed and the source of the faster peak is heavily disputed. To better understand the nature of the fast peak, ion time of flight profiles are investigated for several high-purity metals under ns and fs laser irradiation. Ion peak velocities are compared to material thermal properties to confirm the thermal nature of the slower peak observed under fs laser ablation and its correlation to the ns laser ablation results. The faster ion peak from fs laser ablation does not show any relation to thermal properties and in fact shows similar velocity for all elements investigated, despite widely varying atomic mass. The results combine to confirm the non-thermal nature of the fast ion peak observed under ultrafast laser ablation. (Abstract shortened by UMI.).

Freeman, Justin R.

211

Physical and chemical properties of dust produced in a N{sub 2}-CH{sub 4} RF plasma discharge  

SciTech Connect

Titan's atmospheric chemistry is simulated using a Capacitively Coupled Plasma discharge produced in a N{sub 2}-CH{sub 4} mixture. The produced solid particles are analysed ex-situ. Chemical properties are deduced from: elemental composition, FTIR and LTQ-Orbitrap mass spectrometer. Optical properties are deduced from reflectivity in visible and IR range.

Ouni, F.; Alcouffe, G.; Szopa, C.; Carrasco, N.; Cernogora, G. [Universite de Versailles St Quentin, Service d'Aeronomie, BP 3-91371 Verrieres le Buisson (France); Adande, G.; Thissen, R.; Quirico, E.; Brissaud, O. [LPG-BP 5338041 Grenoble Cedex 9 (France); Schmitz-Afonso, I.; Laprevote, O. [ICSN-CNRS Avenue de la Terrasse, 91198 Gif sur Yvette (France)

2008-09-07

212

Combinatorial plasma polymerization approach to produce thin films for testing cell proliferation.  

PubMed

Plasma enhanced physical vapor depositions are extensively used to fabricate substrates for cell culture applications. One peculiarity of the plasma processes is the possibility to deposit thin films with reproducible chemical and physical properties. In the present work, a combinatorial plasma polymerization process was used to deposit thin carbon based films to promote cell adhesion, in the interest of testing cell proliferation as a function of the substrate chemical properties. Peculiarity of the combinatorial approach is the possibility to produce in just one deposition experiment, a set of surfaces of varying chemical moieties by changing the precursor composition. A full characterization of the chemical, physical and thermodynamic properties was performed for each set of the synthesized surfaces. X-ray photoelectron spectroscopy was used to measure the concentration of carboxyl, hydroxyl and amine functional groups on the substrate surfaces. A perfect linear trend between polar groups' density and precursors' concentration was found. Further analyses reveled that also contact angles and the correspondent surface energies of all deposited thin films are linearly dependent on the precursor concentration. To test the influence of the surface composition on the cell adhesion and proliferation, two cancer cell lines were utilized. The cell viability was assessed after 24 h and 48 h of cell culture. Experiments show that we are able to control the cell adhesion and proliferation by properly changing the thin film deposition conditions i.e. the concentration and the kind of chemical moiety on the substrate surface. The results also highlight that physical and chemical factors of biomaterial surface, including surface hydrophobicity and free energy, chemical composition, and topography, can altered cell attachment. PMID:24121075

Antonini, V; Torrengo, S; Marocchi, L; Minati, L; Dalla Serra, M; Bao, G; Speranza, G

2014-01-01

213

Research of elliptical curved crystal spectrometer for measuring laser-produced plasma x-ray  

NASA Astrophysics Data System (ADS)

A new space and time resolved focusing elliptical curved crystal spectrometer has been developed and applied to diagnose X-ray of laser-produced plasma in 0. 2~2 nm region. According to the theory of Bragg diffraction, four kinds of crystal including LiF, PET, KAP, and MiCa were choosed as dispersive elements.The distance of crystal lattice varies from 0.4 to 2.6 nm. Bragg angle is in the range of 30°~67.5°, the spectral detection angle is in 55.4°~134°. The dispersive crystal sizes are 120×8×0.2mm.The characteristic of optical system is an elliptical geometry.The X-ray source is located at the front focal point.The X-rays diffracted by the elliptically curved crystal are focused at the rear focal point where a width-adjustable exit slit is positioned.The Curved crystal spectrometer mainly consists of dispersive elements, vacuum configuration, aligning device, spectral detectors and three dimensional (3D) micro-adjustment devices. The spectrographic experiment was carried out on the XG-2 laser facility.The PET and KAP crystals are adopted as the dispersive elements,which measure X-ray in the 0.44~0.81 and 1.33~2.46nm region. Emission spectrum of Al plasmas and Ti plasmas have been successfully recorded by using X-ray CCD camera. It is demonstrated experimentally that the measured wavelength is accorded with the theoretical value. At the same time, experimental result shows that spectral resolution of PET and KAP crystals is 956 and 1123.

Zhu, Gang; Zhong, Xian-xin; Xiong, Xian-cai; Feng, Wen-jie

2007-12-01

214

Laser produced plasma sources for nanolithography--Recent integrated simulation and benchmarking  

NASA Astrophysics Data System (ADS)

Photon sources for extreme ultraviolet lithography (EUVL) are still facing challenging problems to achieve high volume manufacturing in the semiconductor industry. The requirements for high EUV power, longer optical system and components lifetime, and efficient mechanisms for target delivery have narrowed investigators towards the development and optimization of dual-pulse laser sources with high repetition rate of small liquid tin droplets and the use of multi-layer mirror optical system for collecting EUV photons. We comprehensively simulated laser-produced plasma sources in full 3D configuration using 10-50 ?m tin droplet targets as single droplets as well as, for the first time, distributed fragmented microdroplets with equivalent mass. The latter is to examine the effects of droplet fragmentation resulting from the first pulse and prior to the incident second main laser pulse. We studied the dependence of target mass and size, laser parameters, and dual pulse system configuration on EUV radiation output and on atomic and ionic debris generation. Our modeling and simulation included all phases of laser target evolution: from laser/droplet interaction, energy deposition, target vaporization, ionization, plasma hydrodynamic expansion, thermal and radiation energy redistribution, and EUV photons collection as well as detail mapping of photons source size and location. We also simulated and predicted the potential damage to the optical mirror collection system from plasma thermal and energetic debris and the requirements for mitigating systems to reduce debris fluence. The debris effect on mirror collection system is analyzed using our three-dimensional ITMC-DYN Monte Carlo package. Modeling results were benchmarked against our CMUXE laboratory experimental studies for the EUV photons production and for debris and ions generation.

Hassanein, A.; Sizyuk, T.

2013-05-01

215

Possible role of ionospheric oxygen in the initiation and development of plasma sheet instabilities  

SciTech Connect

We relate measurements made during substorm growth and expansion to available plasma compositional observations and propose that asymmetries in the distribution of enhanced densities of O/sup +/ (of ionospheric origin) may define regions of the plasma sheet in which tearing mode growth rates are increased and the instability threshold is lowered. We make qualitative estimates of the growth rates of the linear ion tearing mode using statistical models of the dusk-dawn and earthward-tailward distributions of O/sup +/. The theoretical results predict maximum ion tearing growth rate in the range X/sub GSM/ = -10 to -15 R/sub E/ and Y/sub GSM/approx.5 R/sub E/. These values are in reasonable accord with substorm observations since many asymmetries in particle and field phenomena associated with substorms favor the interpretation that substorm onset occurs in the dusk sector of the near-earth plasma sheet. Present results therefore suggest that substorm initiation and development may be closely related to distribution patterns of ionospheric ions.

Baker, D.N.; Hones, E.W. Jr.; Young, D.T.; Birn, J.

1982-12-01

216

Initiation and propagation of coagulation from tissue factor-bearing cell monolayers to plasma: initiator cells do not regulate spatial growth rate.  

PubMed

Exposure of tissue factor (TF)-bearing cells to blood is the initial event in coagulation and intravascular thrombus formation. However, the mechanisms which determine thrombus growth remain poorly understood. To explore whether the procoagulant activity of vessel wall-bound cells regulates thrombus expansion, we studied in vitro spatial clot growth initiated by cultured human cells of different types in contact pathway-inhibited, non-flowing human plasma. Human aortic endothelial cells, smooth muscle cells, macrophages and lung fibroblasts differed in their ability to support thrombin generation in microplate assay with peaks of generated thrombin of 60 +/- 53 nmol L(-1), 135 +/- 57 nmol L(-1), 218 +/- 55 nmol L(-1) and 407 +/- 59 nmol L(-1) (mean +/- SD), respectively. Real-time videomicroscopy revealed the initiation and spatial growth phases of clot formation. Different procoagulant activity of cell monolayers was manifested as up to 4-fold difference in the lag times of clot formation. In contrast, the clot growth rate, which characterized propagation of clotting from the cell surface to plasma, was largely independent of cell type (< or = 30% difference). Experiments with factor VII (FVII)-, FVIII-, FX- or FXI-deficient plasmas and annexin V revealed that (i) cell surface-associated extrinsic Xase was critical for initiation of clotting; (ii) intrinsic Xase regulated only the growth phase; and (iii) the contribution of plasma phospholipid surfaces in the growth phase was predominant. We conclude that the role of TF-bearing initiator cells is limited to the initial stage of clot formation. The functioning of intrinsic Xase in plasma provides the primary mechanism of sustained and far-ranging propagation of coagulation leading to the physical expansion of a fibrin clot. PMID:15670039

Ovanesov, M V; Ananyeva, N M; Panteleev, M A; Ataullakhanov, F I; Saenko, E L

2005-02-01

217

Plasma waves produced by an ion beam: Observations by the VLF experiment on Porcupine  

NASA Astrophysics Data System (ADS)

Results are presented from the VLF electric field experiments flown on Porcupine flights F3 and F4, which also had ejectable xenon ion sources. The xenon ion beam was found to produce plasma instabilities whose frequencies could be linked to the local proton gyrofrequency. The main energy in the instabilities lies at 3kHz for events when the Xe+ source is close to the rocket, and at 7kHz when the source is farther away. Theory predicts that these frequencies should be the lower-hybrid-resonance and this implies that Xe+ is the dominant ion in the first case and that it is the ambient plasma that dominates later. There is no discernable antenna spin-modulation during the Xe events which indicates that the wave k-vectors are not unidirectional. A theory is cited based on the setting up of the proton cyclotron harmonic waves by the Xe+ or 0+ cyclotron harmonic waves. The second Xe+ event on both flights exhibited an, as yet, unexplained harmonic structure related to half the local proton gyrofrequency.

Jones, D.

1980-06-01

218

Simulation of particle velocity in a laser-produced tin plasma extreme ultraviolet source  

SciTech Connect

In connection with fast heating in a laser produced plasma (LPP) extreme ultraviolet (EUV) source, the superheating behavior of bulk tin (Sn) at high heating rates is investigated. A constant temperature and pressure molecular dynamics simulation using modified Lennard-Jones and Coulomb potentials suitable for studying the liquid structure of Sn is employed in order to derive the caloric curves of the solid and liquid phases. The results have shown transient effects on the phase transitions. Superheating is observed during the melting and vaporizing processes. The velocity distribution of Sn particles against typical laser fluence in a LPP EUV light source has been numerically investigated using a simplified method including a one-dimensional, two-temperature, molecular dynamics, and steady-state ionization model. In the framework of our model, it was found that ejected Sn particles have a maximum velocity on the order of 10 to 40 km/s in plasma created using a nanosecond pre-pulse neodymium-doped yttrium aluminum garnet (Nd:YAG, 1.06 {mu}m) laser in EUV lithography experiments.

Masnavi, Majid; Nakajima, Mitsuo; Horioka, Kazuhiko [Department of Energy Sciences, Tokyo Institute of Technology, 4259 Nagatsuta, Midori-ku, Yokohama 226-8502 (Japan); Araghy, Homaira Parchamy [Plasma Physics Research Center, Azad University, Tehran (Iran, Islamic Republic of); Endo, Akira [Friedrich-Schiller University, Institute of Applied Physics, Jena (Germany)

2011-06-15

219

Kinetics of ion and prompt electron emission from laser-produced plasma  

SciTech Connect

We investigated ion emission dynamics of laser-produced plasma from several elements, comprised of metals and non-metals (C, Al, Si, Cu, Mo, Ta, W), under vacuum conditions using a Faraday cup. The estimated ion flux for various targets studied showed a decreasing tendency with increasing atomic mass. For metals, the ion flux is found to be a function of sublimation energy. A comparison of temporal ion profiles of various materials showed only high-Z elements exhibited multiple structures in the ion time of flight profile indicated by the observation of higher peak kinetic energies, which were absent for low-Z element targets. The slower ions were seen regardless of the atomic number of target material propagated with a kinetic energy of 1–5 keV, while the fast ions observed in high-Z materials possessed significantly higher energies. A systematic study of plasma properties employing fast photography, time, and space resolved optical emission spectroscopy, and electron analysis showed that there existed different mechanisms for generating ions in laser ablation plumes. The origin of high kinetic energy ions is related to prompt electron emission from high-Z targets.

Farid, N. [Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States) [Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, School of Physics and Optical Engineering, Dalian University of Technology, Dalian (China); Harilal, S. S.; Hassanein, A. [Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)] [Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States); Ding, H. [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, School of Physics and Optical Engineering, Dalian University of Technology, Dalian (China)] [Key Laboratory of Materials Modification by Laser, Ion and Electron Beams, School of Physics and Optical Engineering, Dalian University of Technology, Dalian (China)

2013-07-15

220

Calibration of a Flat Field Soft X-ray Grating Spectrometer for Laser Produced Plasmas  

SciTech Connect

We have calibrated the x ray response of a variable line spaced grating spectrometer, known as the VSG, at the Fusion and Astrophysics Data and Diagnostic Calibration Facility at the Lawrence Livermore National Laboratory (LLNL). The VSG has been developed to diagnose laser produced plasmas, such as those created at the Jupiter Laser Facility and the National Ignition Facility at LLNL, and at both the Omega and Omega EP lasers at University of Rochester's Laboratory for Laser Energetics. The bandwidth of the VSG spans the range from {approx} 6 to 60 {angstrom}. The calibration results present here include the VSG's dispersion and quantum efficiency. The dispersion is determined by measuring the x rays emitted from hydrogen-like and helium-like ions of carbon, nitrogen, oxygen, neon, and aluminum. The quantum efficiency is calibrated to an accuracy of 30% or better by normalizing the x ray intensities recorded by the VSG to those simultaneously recorded by an x ray microcalorimeter spectrometer.

Park, J; Brown, G V; Schneider, M B; Baldis, H A; Beiersdorfer, P; Cone, K V; Kelley, R L; Kilbourne, C A; Magee, E; May, M J; Porter, F S

2010-05-12

221

3-D effects in magnetic reconnection of laser-produced plasma bubbles  

NASA Astrophysics Data System (ADS)

Recent experiments have observed magnetic reconnection in high-energy-density, laser-produced plasma bubbles. It is of great interest to extend previous 2-D simulations [1] to understand the full 3-D evolution of the bubbles. This 3-D evolution, studied by PIC simulations, includes the 3-D spherical expansion of the bubbles and 3-D geometry of the interaction, including the formation of isolated magnetic nulls and null-null lines. In cylindrical 3-D geometry, we study the dynamics of long-wavelength kink instabilities and short-wavelength lower-hybrid instabilities in the return currents, over a range of parameters characteristic of the experiments. Observational signatures of 3-D dynamics in the experiments will be discussed.[4pt] [1] W. Fox, A. Bhattacharjee, K. Germaschewski, Phys. Rev. Lett. 106, 215003 (2011).

Fox, W.; Mollica, F.; Bhattacharjee, A.; Germaschewski, K.

2011-11-01

222

Magnetic properties of Co-Zr-B magnets produced by spark plasma sintering method  

NASA Astrophysics Data System (ADS)

Magnets of Co-Zr-B, one of the permanent magnetic compounds without rare-earth elements, were successfully produced by the spark plasma sintering method. The resultant Co-Zr-B magnets had high densities of 92%-96% and consisted mainly of the CoxZr (x ? 5) phase. The coercivity of the Co-Zr-B magnets was highly dependent on the consolidation temperature and the boron content. The highest maximum energy product of 6.0 MGOe, with a remanence of 6.4 kG and the coercivity of 4.0 kOe, was achieved by the Co80Zr18B2 magnets consolidated at 873 K.

Saito, Tetsuji; Akiyama, Tomoya

2014-05-01

223

Calibration of a flat field soft x-ray grating spectrometer for laser produced plasmas  

SciTech Connect

We have calibrated the x-ray response of a variable line spaced grating spectrometer, known as the VSG, at the Fusion and Astrophysics Data and Diagnostic Calibration Facility at the Lawrence Livermore National Laboratory (LLNL). The VSG has been developed to diagnose laser produced plasmas, such as those created at the Jupiter Laser Facility and the National Ignition Facility at LLNL and at both the Omega and Omega EP lasers at the University of Rochester's Laboratory for Laser Energetics. The bandwidth of the VSG spans the range of {approx}6-60 A. The calibration results presented here include the VSG's dispersion and quantum efficiency. The dispersion is determined by measuring the x rays emitted from the hydrogenlike and heliumlike ions of carbon, nitrogen, oxygen, neon, and aluminum. The quantum efficiency is calibrated to an accuracy of 30% or better by normalizing the x-ray intensities recorded by the VSG to those simultaneously recorded by an x-ray microcalorimeter spectrometer.

Park, J.; Cone, K. V. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551-0808 (United States); University of California, Davis, One Shields Avenue, Davis, California 95616 (United States); Brown, G. V.; Schneider, M. B.; Beiersdorfer, P.; Magee, E. W.; May, M. J. [Lawrence Livermore National Laboratory, P.O. Box 808, Livermore, California 94551-0808 (United States); Baldis, H. A. [University of California, Davis, One Shields Avenue, Davis, California 95616 (United States); Kelley, R. L.; Kilbourne, C. A.; Porter, F. S. [NASA Goddard Space Flight Center, Greenbelt, Maryland 20770 (United States)

2010-10-15

224

Gas dynamic effects on formation of carbon dimers in laser-produced plasmas  

SciTech Connect

We investigated the effect of helium and nitrogen pressures on the dynamics of molecular species formation during laser ablation of carbon. For producing plasmas, planar carbon targets were irradiated with 1064 nm, 6 ns pulses from an Nd:yttrium aluminum garnet laser. The emission from excited C{sub 2} and CN molecules was studied using space resolved optical time-of-flight emission spectroscopy and spectrally resolved fast imaging. The intensity oscillations in C{sub 2} and CN monochromatic fast imaging and their emission space-time contours suggest that recombination is the major mechanism of C{sub 2} formation within the laser ablation carbon plumes in the presence of ambient gas.

Al-Shboul, K. F.; Harilal, S. S.; Hassanein, A.

2011-09-26

225

Study of ozone-initiated limonene reaction products by low temperature plasma ionization mass spectrometry.  

PubMed

Limonene and its ozone-initiated reaction products were investigated in situ by low temperature plasma (LTP) ionization quadrupole time-of-flight (QTOF) mass spectrometry. Helium was used as discharge gas and the protruding plasma generated ~850 ppb ozone in front of the glass tube by reaction with the ambient oxygen. Limonene applied to filter paper was placed in front of the LTP afterglow and the MS inlet. Instantly, a wide range of reaction products appeared, ranging from m/z 139 to ca. 1000 in the positive mode and m/z 115 to ca. 600 in the negative mode. Key monomeric oxidation products including levulinic acid, 4-acetyl-1-methylcyclohexene, limonene oxide, 3-isopropenyl-6-oxo-heptanal, and the secondary ozonide of limonene could be identified by collision-induced dissociation. Oligomeric products ranged from the nonoxidized dimer of limonene (C20H30) and up to the hexamer with 10 oxygen atoms (C60H90O10). The use of LTP for in situ ozonolysis and ionization represents a new and versatile approach for the assessment of ozone-initiated terpene chemistry. PMID:23666602

Nørgaard, Asger W; Vibenholt, Anni; Benassi, Mario; Clausen, Per Axel; Wolkoff, Peder

2013-07-01

226

Study of Ozone-Initiated Limonene Reaction Products by Low Temperature Plasma Ionization Mass Spectrometry  

NASA Astrophysics Data System (ADS)

Limonene and its ozone-initiated reaction products were investigated in situ by low temperature plasma (LTP) ionization quadrupole time-of-flight (QTOF) mass spectrometry. Helium was used as discharge gas and the protruding plasma generated ~850 ppb ozone in front of the glass tube by reaction with the ambient oxygen. Limonene applied to filter paper was placed in front of the LTP afterglow and the MS inlet. Instantly, a wide range of reaction products appeared, ranging from m/ z 139 to ca. 1000 in the positive mode and m/ z 115 to ca. 600 in the negative mode. Key monomeric oxidation products including levulinic acid, 4-acetyl-1-methylcyclohexene, limonene oxide, 3-isopropenyl-6-oxo-heptanal, and the secondary ozonide of limonene could be identified by collision-induced dissociation. Oligomeric products ranged from the nonoxidized dimer of limonene (C20H30) and up to the hexamer with 10 oxygen atoms (C60H90O10). The use of LTP for in situ ozonolysis and ionization represents a new and versatile approach for the assessment of ozone-initiated terpene chemistry.

Nørgaard, Asger W.; Vibenholt, Anni; Benassi, Mario; Clausen, Per Axel; Wolkoff, Peder

2013-07-01

227

Epithelial overexpression of BDNF and NT4 produces distinct gustatory axon morphologies that disrupt initial targeting  

E-print Network

Epithelial overexpression of BDNF and NT4 produces distinct gustatory axon morphologies Most fungiform taste buds fail to become innervated when BDNF or NT4 is overexpressed in the basal layer of tongue epithelium. Here, we examined when and how overexpression of BDNF and NT4 disrupt

Krimm, Robin

228

Rayleigh-Taylor-Induced Electromagnetic Fields in Laser-Produced Plasmas  

NASA Astrophysics Data System (ADS)

Spontaneous electromagnetic fields can be important to the dynamic evolution of a plasma by directing heat flow as well as providing additional pressures on the conducting fluids through the Lorentz force. Electromagnetic fields are predicted to affect fluid behavior during the core-collapse of supernovae through generation of fields due to hydrodynamic instabilities. In the coronae of stars, self-generated magnetic fields lead to filamentary structure in the hot plasma. Recent experiments by Gregori et al. investigated sources of protogalactic magnetic fields generated by laser-produced shock waves. In inertial confinement fusion experiments, self-generated electromagnetic fields can also play a role and have recently become of great interest to the community. Present day laser facilities provide a unique opportunity to study spontaneous field-generation in these extreme environments under controlled conditions. Instability-induced electromagnetic fields were investigated using a novel monoenergetic-proton radiography system. Fusion protons generated by an 'exploding-pusher' implosion were used to probe laser-irradiated plastic foils with various preimposed surface perturbations. Imaging protons are sensitive to electromagnetic fields and density modulations in the plasma through the Lorentz force and Coulomb collisions, respectively. Corresponding x-ray radiographs of these targets provided mass density distributions and Coulomb effects on protons were assessed using a Monte Carlo code written using the Geant4 framework. Proton fluence distributions were recorded on CR-39 detectors and Fourier analyzed to infer path-integrated field strengths. Rayleigh-Taylor (RT) growth of preimposed surface perturbations generated magnetic fields by the RT-induced Biermann battery and were measured for the first time. Good data were obtained during linear growth and when compared to ideal calculations, demonstrated that field diffusion near the source played an important role. At later times in the plasma evolution, 3-D cellular structures were observed for all foil types. These features were found to be analogous to previously observed filamentary field structures by Seguin et al. in laser-driven spherical targets. Face-on images of these field structures provided good data to quantitatively analyze the size of these features, not previously attainable due to the complexity of the 3-D spherical data. Work presented here demonstrates that these field structures are likely caused by the magnetothermal instability in the underdense corona. (Copies available exclusively from MIT Libraries, libraries.mit.edu/docs - docs mit.edu)

Manuel, Mario J.-E.

229

ROLE OF INITIAL SUCROSE AND PH LEVELS ON NATURAL, HYDROGEN-PRODUCING, ANAEROBE GERMINATION  

Microsoft Academic Search

Anaerobic batch cultures were established to assess natural anaerobic sporulation, germination, and hydrogen production. Heat-shocked soil inocula obtained from a potato field was cultured using sucrose as the substrate. Eleven batch experimental results suggested that baking was an excellent heat-shock treatment to select for spore forming hydrogen-producing bacteria i.e. clostridia from the soil. Sucrose could induce clostridial spore germination and

Steven Van Ginkel; ShihWu Sung; Ling Li

2001-01-01

230

From the regulatory functions of B cells to the identification of cytokine-producing plasma cell subsets.  

PubMed

B lymphocytes have a unique role as antibody-producing cells. Antibodies are key mediators of humoral immunity against infections, and are thought to account for the protection afforded by successful vaccines. B cells can also secrete cytokines and subsequently regulate immune responses mediated by T and innate cells. Remarkably, recent studies identified plasma blasts/plasma cells as the main types of activated B cells producing the cytokines interleukin (IL)-10, IL-35, tumor necrosis factor (TNF)-?, IL-17, and GM-CSF in various contexts in mice. Here, we discuss these observations, which suggest the existence of various subsets of plasma blast/plasma cells distinguishable through their cytokine expression pattern. PMID:24637161

Dang, Van Duc; Hilgenberg, Ellen; Ries, Stefanie; Shen, Ping; Fillatreau, Simon

2014-06-01

231

New scaling relation for ion extraction by external electric field on a barium plasma produced between parallel-plate electrodes  

NASA Astrophysics Data System (ADS)

Parameter dependencies of ion extraction time by an external electric field have been investigated by using barium plasmas suddenly produced between parallel-plate electrodes under a variety of experimental conditions. It is concluded that the ion extraction time can be expressed as the product of exponents of the three controllable parameters, applied voltage, plasma width, and ion density. This scaling relation can estimate the ion extraction time with an accuracy of 15% for a given controllable parameter set, supporting its universality.

Yamada, Kimio; Tetsuka, Tsutomu; Deguchi, Yoshihiro

1991-05-01

232

Traveling-wave laser-produced-plasma energy source for photoionization laser pumping and lasers incorporating said  

DOEpatents

A traveling-wave, laser-produced-plasma, energy source used to obtain single-pass gain saturation of a photoionization pumped laser. A cylindrical lens is used to focus a pump laser beam to a long line on a target. Grooves are cut in the target to present a surface near normal to the incident beam and to reduce the area, and hence increase the intensity and efficiency, of plasma formation.

Sher, Mark H. (Los Altos, CA); Macklin, John J. (Stanford, CA); Harris, Stephen E. (Palo Alto, CA)

1989-09-26

233

Increasing Stabilized Performance Of Amorphous Silicon Based Devices Produced By Highly Hydrogen Diluted Lower Temperature Plasma Deposition.  

DOEpatents

High quality, stable photovoltaic and electronic amorphous silicon devices which effectively resist light-induced degradation and current-induced degradation, are produced by a special plasma deposition process. Powerful, efficient single and multi-junction solar cells with high open circuit voltages and fill factors and with wider bandgaps, can be economically fabricated by the special plasma deposition process. The preferred process includes relatively low temperature, high pressure, glow discharge of silane in the presence of a high concentration of hydrogen gas.

Li, Yaun-Min (Langhorne, PA); Bennett, Murray S. (Langhorne, PA); Yang, Liyou (Plainsboro, NJ)

1999-08-24

234

Increased Stabilized Performance Of Amorphous Silicon Based Devices Produced By Highly Hydrogen Diluted Lower Temperature Plasma Deposition.  

DOEpatents

High quality, stable photovoltaic and electronic amorphous silicon devices which effectively resist light-induced degradation and current-induced degradation, are produced by a special plasma deposition process. Powerful, efficient single and multi-junction solar cells with high open circuit voltages and fill factors and with wider bandgaps, can be economically fabricated by the special plasma deposition process. The preferred process includes relatively low temperature, high pressure, glow discharge of silane in the presence of a high concentration of hydrogen gas.

Li, Yaun-Min (Langhorne, PA); Bennett, Murray S. (Langhorne, PA); Yang, Liyou (Plainsboro, NJ)

1997-07-08

235

Solution of the explosive percolation quest. II. Infinite-order transition produced by initial distributions of clusters  

E-print Network

We describe the effect of power-law initial distributions of clusters on ordinary percolation and its generalizations, specifically, models of explosive percolation processes based on local optimization. These aggregation processes were shown to exhibit continuous phase transitions if the evolution starts from a set of disconnected nodes. Since the critical exponents of the order parameter in explosive percolation transitions turned out to be very small, these transitions were first believed to be discontinuous. In this article we analyze the evolution starting from clusters of nodes whose sizes are distributed according to a power law. We show that these initial distributions change dramatically the position and order of the phase transitions in these problems. We find a particular initial power-law distribution producing a peculiar effect on explosive percolation, namely before the emergence of the percolation cluster, the system is in a "critical phase" with an infinite generalized susceptibility. This cri...

da Costa, R A; Goltsev, A V; Mendes, J F F

2015-01-01

236

Measurements of ion temperature and flow of pulsed plasmas produced by a magnetized coaxial plasma gun device using an ion Doppler spectrometer  

NASA Astrophysics Data System (ADS)

It is important to know surface damage characteristics of plasma-facing component materials during transient heat and particle loads such as type I ELMs. A magnetized coaxial plasma gun (MCPG) device has been used as transient heat and particle source in ELM simulation experiments. Characteristics of pulsed plasmas produced by the MCPG device play an important role for the plasma material interaction. In this study, ion temperature and flow velocity of pulsed He plasmas were measured by an ion Doppler spectrometer (IDS). The IDS system consists of a light collection system including optical fibers, 1m-spectrometer and a 16 channel photomultiplier tube (PMT) detector. The IDS system measures the width and Doppler shift of HeII (468.58 nm) emission line with the time resolution of 1 ?s. The Doppler broadened and shifted spectra were measured with 45 and 135 degree angles with respect to the plasmoid traveling direction. The observed emission line profile was represented by sum of two Gaussian components to determine the temperature and flow velocity. The minor component at around the wavelength of zero-velocity was produced by the stationary plasma. As the results, the ion velocity and temperature were 68 km/s and 19 eV, respectively. Thus, the He ion flow energy is 97 eV. The observed flow velocity agrees with that measured by a time of flight technique.

Kitagawa, Y.; Sakuma, I.; Iwamoto, D.; Kikuchi, Y.; Fukumoto, N.; Nagata, M.

2012-10-01

237

Effects of initially energetic electrons on relativistic laser-driven electron plasma waves  

SciTech Connect

In this paper, using kinetic calculations and accurate 1D2V particle-in-cell simulations, we point out the important role of initially energetic electrons of the distribution tail in the behavior of high amplitude electron plasma waves (EPWs). In the presence of these electrons, the conventional warm fluid theory (WFT) breaks at very high wave amplitudes that are still noticeably lower than the wave breaking amplitude (WBA). The fluid breakdown results in electron super-heating with respect to the adiabatic laws. Indeed, a new kinetic regime of the relativistic EPWs appears below the WBA. It is argued that the mentioned super-heating results in WBA values lower than the corresponding WFT prediction.

Yazdanpanah, J., E-mail: jamal.yazdan@gmail.com; Anvari, A. [Department of Physics, Sharif University of Technology, P.O. Box 1155-4161, Tehran (Iran, Islamic Republic of)] [Department of Physics, Sharif University of Technology, P.O. Box 1155-4161, Tehran (Iran, Islamic Republic of)

2014-02-15

238

Neutropenia-associated ELANE mutations disrupting translation initiation produce novel neutrophil elastase isoforms  

PubMed Central

Hereditary neutropenia is usually caused by heterozygous germline mutations in the ELANE gene encoding neutrophil elastase (NE). How mutations cause disease remains uncertain, but two hypotheses have been proposed. In one, ELANE mutations lead to mislocalization of NE. In the other, ELANE mutations disturb protein folding, inducing an unfolded protein response in the endoplasmic reticulum (ER). In this study, we describe new types of mutations that disrupt the translational start site. At first glance, they should block translation and are incompatible with either the mislocalization or misfolding hypotheses, which require mutant protein for pathogenicity. We find that start-site mutations, instead, force translation from downstream in-frame initiation codons, yielding amino-terminally truncated isoforms lacking ER-localizing (pre) and zymogen-maintaining (pro) sequences, yet retain essential catalytic residues. Patient-derived induced pluripotent stem cells recapitulate hematopoietic and molecular phenotypes. Expression of the amino-terminally deleted isoforms in vitro reduces myeloid cell clonogenic capacity. We define an internal ribosome entry site (IRES) within ELANE and demonstrate that adjacent mutations modulate IRES activity, independently of protein-coding sequence alterations. Some ELANE mutations, therefore, appear to cause neutropenia via the production of amino-terminally deleted NE isoforms rather than by altering the coding sequence of the full-length protein. PMID:24184683

Tidwell, Timothy; Wechsler, Jeremy; Nayak, Ramesh C.; Trump, Lisa; Salipante, Stephen J.; Cheng, Jerry C.; Donadieu, Jean; Glaubach, Taly; Corey, Seth J.; Grimes, H. Leighton; Lutzko, Carolyn; Cancelas, Jose A.

2014-01-01

239

Evolution of Plasma Waveguide Produced by a Relativistically Self-Guided Laser Pulse  

Microsoft Academic Search

A channel of plasma density depression was created in an underdense plasma by a relativistically self-guided laser pulse(R. Wagner et al.), Phys. Rev. Lett. 78, 3125 (1997).. The hydrodynamic evolution of this channel following electron cavitation and rapid heating was investigated by use of interferometric probing. Guiding of a second pulse in this plasma depression channel and its effect on

A. Maksimchuk; G. S. Sarkisov; S.-Y. Chen; R. Wagner; N. Saleh; D. Umstadter

1997-01-01

240

Investigation on recovery of gap insulation strength and EUV radiation in the post-discharge stage of a laser-triggered discharge produced tin plasma EUV source  

NASA Astrophysics Data System (ADS)

This paper presents an investigation on the recovery of gap insulation strength and extreme ultraviolet (EUV) radiation in the post-discharge stage of a laser-triggered discharge produced tin plasma (LTDPP) EUV source. Gap insulation strength recovers more quickly under a shorter gap length. The gap breakdown voltage recovered to 19.4?kV with a breakdown probability of 25% at 80?µs after an 8?J discharge under a 2.5?mm gap. The same discharge energy under a 5?mm gap required 140?µs for equal recovery. The EUV radiation recovery process was measured utilizing a double laser triggered discharge system. EUV radiation recovery lagged behind the gap insulation strength recovery for both the 2.5 and 5?mm gap. In the case of the 8?J input pulse energy, EUV radiation recovered to the same level as the first EUV pulse at about 600 and 160?µs for the 5 and 2.5?mm gaps, corresponding to a 1.67?kHz and 6.25?kHz repetition rate, respectively. In the case of the 2.5?mm gap and 4?J input pulse energy, our EUV source could work with a repetition rate of upto 23?kHz, enabling the EUV output to reach 345?W/2?sr which was 4.5 times as the value of the 5?mm gap and 8?J input energy. To discuss the slower EUV radiation process, the initial laser trigger phase and plasma pinch stage during the first and second laser-triggered discharge were visualized by means of high speed visible light imaging and laser Schlieren imaging. Comparative results suggest that tin droplets influenced the initial laser-produced plasma plume, consequently affecting the Z-pinch plasma dynamics and its EUV radiation which resulted in the delayed EUV recovery process.

Lu, P.; Kitajima, S.; Lim, S.; Katsuki, S.; Akiyama, H.; Teramoto, Y.

2014-10-01

241

Solid oxide fuel cell electrolytes produced by a combination of suspension plasma spray and very low pressure plasma spray.  

SciTech Connect

Plasma spray coating techniques allow unique control of electrolyte microstructures and properties as well as facilitating deposition on complex surfaces. This can enable significantly improved solid oxide fuel cells (SOFCs), including non-planar designs. SOFCs are promising because they directly convert the oxidization of fuel into electrical energy. However, electrolytes deposited using conventional plasma spray are porous and often greater than 50 microns thick. One solution to form dense, thin electrolytes of ideal composition for SOFCs is to combine suspension plasma spray (SPS) with very low pressure plasma spray (VLPPS). Increased compositional control is achieved due to dissolved dopant compounds in the suspension that are incorporated into the coating during plasma spraying. Thus, it is possible to change the chemistry of the feed stock during deposition. In the work reported, suspensions of sub-micron diameter 8 mol.% Y2O3-ZrO2 (YSZ) powders were sprayed on NiO-YSZ anodes at Sandia National Laboratories (SNL) Thermal Spray Research Laboratory (TSRL). These coatings were compared to the same suspensions doped with scandium nitrate at 3 to 8 mol%. The pressure in the chamber was 2.4 torr and the plasma was formed from a combination of argon and hydrogen gases. The resultant electrolytes were well adhered to the anode substrates and were approximately 10 microns thick. The microstructure of the resultant electrolytes will be reported as well as the electrolyte performance as part of a SOFC system via potentiodynamic testing and impedance spectroscopy.

Slamovich, Elliot (Purdue University, West Lafayette, IN); Fleetwood, James (Purdue University, West Lafayette, IN); McCloskey, James F.; Hall, Aaron Christopher; Trice, Rodney Wayne (Purdue University, West Lafayette, IN)

2010-07-01

242

Initial results of strand produced in Phase 2 of the SSCL Vendor Qualification Program  

SciTech Connect

In 1991, the Superconducting Super Collider Laboratory (SSCL) instituted a program to qualify specific superconductor manufacturers for production of cable acceptable for use in both Collider Dipole (CDM) and Quadrupole (CQM) magnets. The SSCL Vendor Qualification Program (VQP) was designed with two Phases. Phase 1 was divided into two additional phases, 1A and 1B, which ran concurrently. In Phase 1B, each vendor was directed to manufacture roughly 3000 kg of cable using a ``baseline`` process. The baseline process was agreed to by both the SSCL and the vendor at the beginning of the VQP. In this phase, process control was closely monitored with the use of statistical methods and each vendor was graded based on these results. Phase 1A, known as the R&D phase, was developed to allow each vendor an opportunity to optimize and improve on their baseline process in terms of both cost and manufacturability. In this phase, multifilament billets were designed to explore several key variables such as alternate alloy sources, process modifications and improved billet designs. At the end of Phase 1, the results from both 1A and 1B were evaluated at a review between the SSCL and each vendor, and a final Phase 2 process was generated and fixed using the best results. In Phase 2, each vendor is required to manufacture roughly 6000 kg of superconducting cable under a firm fixed price contract which can then be used to create an accurate price estimate for competitive bidding on the full rate production CDM and CQM contracts. At the end of Phase 2, each vendor must meet the minimum requirements outlined in the contract to become a qualified superconducting cable supplier. For one requirement, critical process variables identified by the SSCL Conductor Department at the beginning of the VQP will be evaluated to determine the quality and uniformity of the material produced during Phase 2 of the program.

Erdmann, M.; Capone, D. II; Coleman, S.; Jones, B.; Seuntjens, J.

1993-05-01

243

Structural and optical properties of CR-39 polymer implanted with laser produced plasma ions of iron  

NASA Astrophysics Data System (ADS)

A passive Q-switched Nd:YAG pulsed laser was used to irradiate 99.99% pure Fe target in vacuum ~10-3 Torr. The CR-39 specimens were exposed to laser produced plasma ions (40-250 keV) emitted along the normal to the Fe target surface. The flux of Fe ions was varied by varying the number of laser shots in the range 500-1500 with an increment of 250. A comparison of structural and optical properties of CR-39 polymer before and after ion implantation was made. The increase in ion flux leads to the transformation of polymer into rather more disordered amorphous state leading to the broadening of XRD peaks. The crystallite size decreases (3.547 to 1.618 nm) and Urbach energy increases (0.232 to 0.291 eV) exponentially with the increase in ion flux (0 to 6.07×105 ions/cm2). Indirect optical band gap is found to decrease (4.118 to 3.917 eV) linearly with the increase in ion flux (3.03×105 to 6.07×105 ions/cm2).

Butt, M. Z.; Ali, Dilawar; Najm-ul-Aarifeen; Naseem, S.

2014-12-01

244

Laser-produced plasma measurement of thermal diffusivity of molten metals  

SciTech Connect

We have shown that a laser-produced plasma plume which is representative in composition of the condensed phase target can be reproducibly generated if the movement of the surface due to evaporation is kept in pace with the thermal diffusion front propagating into the bulk. The resulting mass loss is then strongly controlled by the thermal diffusivity of the target matter, and this relationship has been exploited to measure the thermal diffusivity of metallic alloys. We have developed a novel RF levitator-heater as a contamination-free molten metal source to be used as a target for LPP plume generation. In order to determine the mass loss due to LPP excitation, a new high sensitivity transducer has been constructed for measurement of the resulting impulse imparted on the specimen. The impulse transducer is built onto the specimen holder within the levitation-assisted molten metal source. The LPP method has been fully excercised for measurement of the thermal diffusivity of a molten specimen relative to the value for its room temperature solid. The results for SS304 and SS316 are presented together with a critique of the results. A numerical modeling of specimen heating in the molten metal source and the physical basis of the new hod are also presented.

Kim, Yong W.; Park, C.S. [Lehigh Univ., Bethlehem, PA (United States)

1995-12-01

245

Instantaneous x-ray radiation energy from laser produced polystyrene plasmas for shock ignition conditions  

SciTech Connect

Laser target energy coupling mechanism is crucial in the shock ignition (SI) scheme, and x-ray radiation energy is a non-negligible portion of the laser produced plasma energy. To evaluate the x-ray radiation energy amount at conditions relevant to SI scheme, instantaneous x-ray radiation energy is investigated experimentally with continuum phase plates smoothed lasers irradiating layer polystyrene targets. Comparative laser pulses without and with shock spike are employed. With the measured x-ray angular distribution, full space x-ray radiation energy and conversion efficiency are observed. Instantaneous scaling law of x-ray conversion efficiency is obtained as a function of laser intensity and time. It should be pointed out that the scaling law is available for any laser pulse shape and intensity, with which irradiates polystyrene planar target with intensity from 2 × 10{sup 14} to 1.8 × 10{sup 15} W/cm{sup 2}. Numerical analysis of the laser energy transformation is performed, and the simulation results agree with the experimental data.

Shang, Wanli; Wei, Huiyue; Li, Zhichao; Yi, Rongqing; Zhu, Tuo; Song, Tianmin; Huang, Chengwu; Yang, Jiamin [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China)] [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China)

2013-10-15

246

Chemically produced nanostructured ODS-lanthanum oxide-tungsten composites sintered by spark plasma  

NASA Astrophysics Data System (ADS)

High purity W and W-0.9La 2O 3 (wt.%) nanopowders were produced by a wet chemical route. The precursor was prepared by the reaction of ammonium paratungstate (APT) with lanthanum salt in aqueous solutions. High resolution electron microscopy investigations revealed that the tungstate particles were coated with oxide precipitates. The precursor powder was reduced to tungsten metal with dispersed lanthanum oxide. Powders were consolidated by spark plasma sintering (SPS) at 1300 and 1400 °C to suppress grain growth during sintering. The final grain size relates to the SPS conditions, i.e. temperature and heating rate, regardless of the starting powder particle size. Scanning electron microscopy revealed that oxide phases were mainly accumulated at grain boundaries while the tungsten matrix constituted of nanosized sub-grains. The transmission electron microscopy revealed that the tungsten grains consist of micron-scale grains and finer sub-grains. EDX analysis confirmed the presence of W in dispersed oxide phases with varying chemical composition, which evidenced the presence of complex oxide phases (W-O-La) in the sintered metals.

Yar, Mazher Ahmed; Wahlberg, Sverker; Bergqvist, Hans; Salem, Hanadi G.; Johnsson, Mats; Muhammed, Mamoun

2011-01-01

247

Man-made vitreous fiber produced from incinerator ash using the thermal plasma technique and application as reinforcement in concrete.  

PubMed

This study proposes using thermal plasma technology to treat municipal solid waste incinerator ashes. A feasible fiberization method was developed and applied to produce man-made vitreous fiber (MMVF) from plasma vitrified slag. MMVF were obtained through directly blending the oxide melt stream with high velocity compressed air. The basic technological characteristics of MMVF, including morphology, diameter, shot content, length and chemical resistance, are described in this work. Laboratory experiments were conducted on the fiber-reinforced concrete. The effects of fibrous content on compressive strength and flexural strength are presented. The experimental results showed the proper additive of MMVF in concrete can enhance its mechanical properties. MMVF products produced from incinerator ashes treated with the thermal plasma technique have great potential for reinforcement in concrete. PMID:20580155

Yang, Sheng-Fu; Wang, To-Mai; Lee, Wen-Cheng; Sun, Kin-Seng; Tzeng, Chin-Ching

2010-10-15

248

Solution of the explosive percolation quest. II. Infinite-order transition produced by initial distributions of clusters  

E-print Network

We describe the effect of power-law initial distributions of clusters on ordinary percolation and its generalizations, specifically, models of explosive percolation processes based on local optimization. These aggregation processes were shown to exhibit continuous phase transitions if the evolution starts from a set of disconnected nodes. Since the critical exponents of the order parameter in explosive percolation transitions turned out to be very small, these transitions were first believed to be discontinuous. In this article we analyze the evolution starting from clusters of nodes whose sizes are distributed according to a power law. We show that these initial distributions change dramatically the position and order of the phase transitions in these problems. We find a particular initial power-law distribution producing a peculiar effect on explosive percolation, namely before the emergence of the percolation cluster, the system is in a "critical phase" with an infinite generalized susceptibility. This critical phase is absent in ordinary percolation models with any power-law initial conditions. The transition from the critical phase is an infinite order phase transition, which resembles the scenario of the Berezinskii-Kosterlitz-Thouless phase transition. We obtain the critical singularity of susceptibility at this peculiar infinite-order transition in explosive percolation. It turns out that the susceptibility in this situation does not obey the Curie-Weiss law.

R. A. da Costa; S. N. Dorogovtsev; A. V. Goltsev; J. F. F. Mendes

2015-01-06

249

Charged-particle acceleration and energy loss in laser-produced plasmas D. G. Hicks,a)  

E-print Network

Charged-particle acceleration and energy loss in laser-produced plasmas D. G. Hicks,a) C. K. Li, F, particle energy shifts were dominated by acceleration effects. Using a simple model for the accelerating T. R. Boehly et al., Opt. Commun. 133, 495 1997 . Comparing the energy shifts of four particle types

250

Excitation wavelength dependence of water-window line emissions from boron-nitride laser-produced plasmas  

E-print Network

Excitation wavelength dependence of water-window line emissions from boron-nitride laser of laser excitation wavelength on water-window emission lines of laser- produced boron-nitride plasmas:YAG laser on BN target in vacuum. Soft x-ray emission lines in the water-window region are recorded using

Harilal, S. S.

251

PUBLISHED ONLINE: 13 NOVEMBER 2011 | DOI: 10.1038/NPHYS2130 Collisionless shocks in laser-produced plasma  

E-print Network

of focusable, high-energy proton beams. In addition, certain ap- plications such as hadron therapy-produced plasma generate monoenergetic high-energy proton beams Dan Haberberger1 , Sergei Tochitsky1 , Frederico accelerate proton beams to 20 MeV with extremely narrow energy spreads of about 1% and low emittances

Loss, Daniel

252

Persistence of uranium emission in laser-produced plasmas N. L. LaHaye, S. S. Harilal,a)  

E-print Network

Persistence of uranium emission in laser-produced plasmas N. L. LaHaye, S. S. Harilal,a) P. K; published online 22 April 2014) Detection of uranium and other nuclear materials is of the utmost importance of special nuclear materials (SNMs), such as uranium and thorium, is of particular interest to many agen

Harilal, S. S.

253

LASERS: Self-initiating volume discharge in iodides used for producing atomic iodine in pulsed chemical oxygen — iodine lasers  

NASA Astrophysics Data System (ADS)

A volume self-sustained discharge (VSD) in iodides (C3H7I, C4H9I) and in their mixtures with SF6, N2, and O2 in the presence of small-scale inhomogeneities on the cathode surface is shown to develop in the form of a self-initiating volume discharge (SIVD), i.e., a volume discharge without any preionisation including discharge gaps with a strong edge enhancement of the electric field. Additions of SF6 or N2 to the iodides improves the stability and homogeneity of the SIVD, while adding up to 300 % (relative to the partial iodide pressure) of O2 to these mixtures has only an insignificant effect on the discharge stability. The possibility of SIVD initiation was modelled experimentally in a 1.5-L discharge volume. For the C4H9I:O2:SF6=0.083:0.25:0.67 mixture at a pressure of 72 Torr, the specific energy input into the discharge plasma ranged up to 130 J L-1 in this geometry. A conclusion was drawn that the SIVD is promising for the production of atomic iodine in the pulsed and repetitively pulsed operating regimes of a chemical oxygen — iodine laser.

Belevtsev, A. A.; Kazantsev, S. Yu; Saifulin, A. V.; Firsov, K. N.

2003-06-01

254

Development of a Laser-Produced Plasma X-ray source for Phase-Contrast Radiography of DT Ice layers  

SciTech Connect

Refraction enhanced x-ray phase contrast imaging is crucial for characterization of deuterium-tritium (DT) ice layer roughness in optically opaque inertial confinement fusion capsules. To observe the time development of DT ice roughness over {approx} second timescales, we need a bright x-ray source that can produce an image faster than the evolution of the ice surface roughness. A laser produced plasma x-ray source is one of the candidates that can meet this requirement. We performed experiments at the Janus laser facility at Lawrence Livermore National Laboratory and assessed the characteristics of the laser produced plasma x-ray source as a potential backlight for in situ target characterization.

Izumi, N; Dewald, E; Kozioziemski, B; Landen, O L; Koch, J A

2008-07-21

255

Excitation wavelength dependence of water-window line emissions from boron-nitride laser-produced plasmas  

SciTech Connect

We investigated the effects of laser excitation wavelength on water-window emission lines of laser-produced boron-nitride plasmas. Plasmas are produced by focusing 1064 nm and harmonically generated 532 and 266 nm radiation from a Nd:YAG laser on BN target in vacuum. Soft x-ray emission lines in the water-window region are recorded using a grazing-incidence spectrograph. Filtered photodiodes are used to obtain complementary data for water-window emission intensity and angular dependence. Spectral emission intensity changes in nitrogen Ly-{alpha} and He-{alpha} are used to show how laser wavelength affects emission. Our results show that the relative intensity of spectral lines is laser wavelength dependent, with the ratio of Ly-{alpha} to He-{alpha} emission intensity decreasing as laser wavelength is shortened. Filtered photodiode measurements of angular dependence showed that 266 and 532 nm laser wavelengths produce uniform emission.

Crank, M.; Harilal, S. S.; Hassan, S. M.; Hassanein, A. [Center for Materials Under Extreme Environment, School of Nuclear Engineering, Purdue University, West Lafayette, Indiana 47907 (United States)

2012-02-01

256

Real-time measurement of materials properties at high temperatures by laser produced plasmas  

NASA Technical Reports Server (NTRS)

Determination of elemental composition and thermophysical properties of materials at high temperatures, as visualized in the context of containerless materials processing in a microgravity environment, presents a variety of unusual requirements owing to the thermal hazards and interferences from electromagnetic control fields. In addition, such information is intended for process control applications and thus the measurements must be real time in nature. A new technique is described which was developed for real time, in-situ determination of the elemental composition of molten metallic alloys such as specialty steel. The technique is based on time-resolved spectroscopy of a laser produced plasma (LPP) plume resulting from the interaction of a giant laser pulse with a material target. The sensitivity and precision were demonstrated to be comparable to, or better than, the conventional methods of analysis which are applicable only to post-mortem specimens sampled from a molten metal pool. The LPP technique can be applied widely to other materials composition analysis applications. The LPP technique is extremely information rich and therefore provides opportunities for extracting other physical properties in addition to the materials composition. The case in point is that it is possible to determine thermophysical properties of the target materials at high temperatures by monitoring generation and transport of acoustic pulses as well as a number of other fluid-dynamic processes triggered by the LPP event. By manipulation of the scaling properties of the laser-matter interaction, many different kinds of flow events, ranging from shock waves to surface waves to flow induced instabilities, can be generated in a controllable manner. Time-resolved detection of these events can lead to such thermophysical quantities as volume and shear viscosities, thermal conductivity, specific heat, mass density, and others.

Kim, Yong W.

1990-01-01

257

Carbon/platinum nanotextured films produced by plasma sputtering Herv Rabat1,2  

E-print Network

to the film/support interface. Optimized catalytic layers were formed at low plasma pressure operation ( of catalytic reactions [15,16]. Although very few studies are devoted to low pressure plasma deposition of catalytic thin films, the latter is expected to be advantageous for controlling low catalyst content

Paris-Sud XI, Université de

258

Cold Plasma Inactivates Salmonella and Escherichia coli O157:H7 on Fresh Produce  

Technology Transfer Automated Retrieval System (TEKTRAN)

This presentation will summarize recent advances in cold plasma technology at the USDA’s Eastern Regional Research Center. Cold plasma generated in a gliding arc was applied to outbreak strains of Escherichia coli O157:H7 and Salmonella Stanley inoculated on the surfaces of golden delicious apples. ...

259

Structural analysis of silicon dioxide and silicon oxynitride films produced using an oxygen plasma  

Microsoft Academic Search

Plasma grown silicon dioxide and oxynitride layers are shown to represent, for microelectronic applications, a good alternative method to conventional thermally grown layers. Fast growth rates, together with good electrical properties are demonstrated, at low process temperatures. Growth kinetics of SiO2 layers synthesized both in RF and microwave plasma anodization systems are presented for a wide range of substrate temperatures

Octavian Buiu; Gary P. Kennedy; Mariuca Gartner; Stephen Taylor

1998-01-01

260

Propagation of charge-exchange plasma produced by an ion thruster  

NASA Technical Reports Server (NTRS)

Under the proper conditions there is an end-effect of a long, cylindrical Langmuir probe which allows a significant increase in collected ion current when the probe is aligned with a flowing plasma. This effect was used to determine the charge-exchange plasma flow direction at various locations relative to the ion thruster. The ion current collected by the probe as a function of its angle with respect to the plasma flow allows determination of the plasma density and plasma flow velocity at the probe's location upstream of the ion thruster optics. The density values obtained from the ion current agreed to within a factor of two of density values obtained by typical voltage-current Langmuir probe characteristics.

Carruth, M. R., Jr.; Brady, M. E.

1981-01-01

261

The initial events in myelin synthesis: orientation of proteolipid protein in the plasma membrane of cultured oligodendrocytes  

Microsoft Academic Search

Proteolipid protein (PLP) is the most abun- dant transmembrane protein in myelin of the central nervous system. Conflicting models of PLP topology have been generated by computer predictions based on its primary sequence and experiments with purified myelin. We have examined the initial events in myelin synthesis, including the insertion and orientation of PLP in the plasma membrane, in rat

Lynn D. Hudson; Victor L. Friedrich; Toby Behar; Monique Dubois-Dalcq; Robert A. Lazzarini

1989-01-01

262

The Influence of spot size on the expansion dynamics of nanosecond-laser-produced copper plasmas in atmosphere  

SciTech Connect

Laser produced copper plasmas of different spot sizes in air were investigated using fast photography and optical emission spectroscopy (OES). The laser energy was 33 mJ. There were dramatic changes in the plasma plume expansion into the ambient air when spot sizes changed from {approx}0.1 mm to {approx}0.6 mm. A stream-like structure and a hemispherical structure were, respectively, observed. It appeared that the same spot size resulted in similar expansion dynamics no matter whether the target was located in the front of or behind the focal point, although laser-induced air breakdown sometimes occurred in the latter case. Plasma plume front positions agree well with the classic blast wave model for the large spot-size cases, while an unexpected stagnation of {approx}80 ns occurred after the laser pulse ends for the small spot size cases. This stagnation can be understood in terms of the evolution of enhanced plasma shielding effects near the plasma front. Axial distributions of plasma components by OES revealed a good confinement effect. Electron number densities were estimated and interpreted using the recorded Intensified Charge Coupled Device (ICCD) images.

Li, Xingwen; Wei, Wenfu; Wu, Jian; Jia, Shenli; Qiu, Aici [State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, No. 28 XianNing West Road, Xi'an, Shaanxi Province 710049 (China)] [State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, No. 28 XianNing West Road, Xi'an, Shaanxi Province 710049 (China)

2013-06-28

263

The Influence of spot size on the expansion dynamics of nanosecond-laser-produced copper plasmas in atmosphere  

NASA Astrophysics Data System (ADS)

Laser produced copper plasmas of different spot sizes in air were investigated using fast photography and optical emission spectroscopy (OES). The laser energy was 33 mJ. There were dramatic changes in the plasma plume expansion into the ambient air when spot sizes changed from ˜0.1 mm to ˜0.6 mm. A stream-like structure and a hemispherical structure were, respectively, observed. It appeared that the same spot size resulted in similar expansion dynamics no matter whether the target was located in the front of or behind the focal point, although laser-induced air breakdown sometimes occurred in the latter case. Plasma plume front positions agree well with the classic blast wave model for the large spot-size cases, while an unexpected stagnation of ˜80 ns occurred after the laser pulse ends for the small spot size cases. This stagnation can be understood in terms of the evolution of enhanced plasma shielding effects near the plasma front. Axial distributions of plasma components by OES revealed a good confinement effect. Electron number densities were estimated and interpreted using the recorded Intensified Charge Coupled Device (ICCD) images.

Li, Xingwen; Wei, Wenfu; Wu, Jian; Jia, Shenli; Qiu, Aici

2013-06-01

264

Channeling of microwave radiation in a double line containing a plasma filament produced by intense femtosecond laser pulses in air  

SciTech Connect

The channeling of microwave radiation is demonstrated experimentally in a double line in which a plasma filament produced in air by intense femtosecond laser pulses serves as one of the conductors. It is shown that during the propagation of microwave radiation in this line, ultrashort pulses are formed, their duration monotonically decreasing with increasing the propagation length (down to the value comparable with the microwave field period). These effects can be used for diagnostics of plasma in a filament. (laser applications and other topics in quantum electronics)

Bogatov, N A; Kuznetsov, A I; Smirnov, A I; Stepanov, A N [Institute of Applied Physics, Russian Academy of Sciences, Nizhnii Novgorod (Russian Federation)

2009-10-31

265

Plasma zinc concentration responds rapidly to the initiation and discontinuation of short-term zinc supplementation in healthy men.  

PubMed

To assist with the evaluation of zinc (Zn) intervention programs, information is needed on the magnitude and velocity of response of plasma Zn concentration following changes in Zn intake. Our objective in this study was to measure plasma Zn concentration of healthy adult men before and after initiation and discontinuation of 1 of 2 dosages of Zn supplements or placebo. We conducted a randomized, double-blind, placebo-controlled trial in 58 apparently healthy males aged 19-54 y. Participants received 1 of 3 liquid supplements daily for 21 d: 10 or 20 mg Zn/d, as Zn sulfate, or placebo. Fasting plasma Zn concentrations were measured on 14 occasions before, during, and after supplementation. Data were analyzed using mixed-model ANCOVA. The plasma Zn concentration was related to day of study (P < 0.0001) and study group (P < 0.0001). Controlling for baseline concentrations, plasma Zn concentrations were consistently elevated above baseline by d 5 among individuals in both of the Zn-supplemented groups compared with those receiving placebo supplements, regardless of their initial plasma Zn concentration. There were no significant group-wise differences between those who received either 10 or 20 mg/d Zn. Plasma Zn concentrations of supplemented individuals declined following withdrawal of supplementation and within 2 wk no longer differed from those of the placebo group. Change in the plasma Zn concentration is a useful indicator to monitor compliance with, and possibly effectiveness of, Zn supplementation programs. To ensure accurate interpretation of the results, samples should be collected while the intervention is still in progress. PMID:20943956

Wessells, K Ryan; Jorgensen, Joshua M; Hess, Sonja Y; Woodhouse, Leslie R; Peerson, Janet M; Brown, Kenneth H

2010-12-01

266

Dependence of terahertz power from laser-produced plasma on laser intensity  

SciTech Connect

Power of terahertz radiation from plasma which is generated from air irradiated by coupled ({omega}, 2{omega}) femtosecond laser pulses is analyzed for high laser intensities, for which non-linear plasma effects on the pulse propagation become essential, with multidimensional particle-in-cell simulations including the self-consistent plasma kinetics. The growth rate of THz power becomes slower as the laser intensity increases. A reason of such a lowering of efficiency in THz emission is found to be ionization of air by the laser pulse, which results in poor focusing of laser pulses.

Shin, J.-H.; Zhidkov, A.; Jin, Z.; Hosokai, T.; Kodama, R. [Graduate School of Engineering, Osaka University, 2-1, Yamadaoka, Suita, Osaka 565-0871 (Japan); Photon Pioneers Center, Osaka University, 2-1, Yamadaoka, Suita, Osaka 565-0871 (Japan); Japan Institute of Laser Engineering, Osaka University, 2-6 Yamadaoka (Japan)

2012-07-11

267

Rayleigh-Taylor-Induced electromagnetic fields in laser-produced plasmas  

E-print Network

Spontaneous electromagnetic fields can be important to the dynamic evolution of a plasma by directing heat flow as well as providing additional pressures on the conducting fluids through the Lorentz force. Electromagnetic ...

Manuel, Mario John-Errol

2013-01-01

268

Refraction-enhanced x-ray radiography for inertial confinement fusion and laser-produced plasma applications  

SciTech Connect

We explore various laser-produced plasma and inertial confinement fusion applications of phase-contrast x-ray radiography, and we show how the main features of these enhancements can be considered from a geometrical optics perspective as refraction enhancements. This perspective simplifies the analysis and often permits simple analytical formulas to be derived that predict the enhancements. We explore a raytrace approach to various material interface applications, and we explore a more general example of refractive bending of x rays by an implosion plasma. We find that refraction-enhanced x-ray radiography of implosions may provide a means to quantify density differences across shock fronts as well as density variations caused by local heating due to high-Z dopants. We also point out that refractive bending by implosions plasmas can blur fine radiograph features and can also provide misleading contrast information on area-backlit pinhole imaging experiments unless its effects are taken into consideration.

Koch, Jeffrey A.; Landen, Otto L.; Kozioziemski, Bernard J.; Izumi, Nobuhiko; Dewald, Eduard L.; Salmonson, Jay D.; Hammel, Bruce A. [Lawrence Livermore National Laboratory, P.O. Box 808, L-481, Livermore, California 94551 (United States)

2009-06-01

269

Imaging X-ray crystal spectrometer for laser-produced plasmas  

Microsoft Academic Search

X-ray Thomson scattering (XRTS) is a powerful technique for measuring state variables in dense plasmas. In this paper, we report on the development of a one-dimensional imaging spectrometer for use in characterizing spatially nonuniform, dense plasmas using XRTS. Diffraction of scattered x-rays from a toroidally curved crystal images along a one-dimensional spatial profile while simultaneously spectrally resolving along the other.

E. J. Gamboa; D. S. Montgomery; I. M. Hall; R. P. Drake

2011-01-01

270

Emission Produced at Compression of Deuterium Current-Sheath with Wire in Plasma Focus Discharge  

Microsoft Academic Search

The implosion of a deuterium plasma toward an Al wire was performed at the current amplitudes of 1.5-1.8 MA. The Al wire of 120 mum diameter and 4-5 cm length was placed on the top of the inner electrode. Pulses of XUV radiation and soft X-rays were detected at the maximum compression of the plasma focus column. They contained lines

Pavel Kubes; Jozef Kravárik; Daniel Klír; Marek Scholz; Marian Paduch; Krzysztof Tomaszewski; Irena Ivanova-Stanik; Barbara Bienkowska; Leslaw Karpinski; Leszek Ryc; Libor Juha; Josef Krása; Marek J. Sadowski; Lech Jakubowski; Adam Szydlowski; Aneta Banaszak; Hellmut Schmidt; Vera M. Romanova

2002-01-01

271

Characteristics of ICR-produced peripheral plasma in the Uragan-3M torsatron  

NASA Astrophysics Data System (ADS)

Some plasma parameters outside the confinement volume near the last closed magnetic surface (LCMS) and in the divertor fluxes were studied by probe and microwave techniques during ICR production and heating of the plasma in the Uragan-3M torsatron. When moving around the LCMS, the steepness of the radial density, electron temperature, and potential profiles increase with distance away from the 'rib' of the LCMS. The quasi-steady radial electric field E(sub r) near the LCMS exceeds 100 V/cm and is directed outwards, opposite to the calculated ambipolar electric field inside the confinement volume. It is shown that the total flow of the diverted plasma in the spacing between two helical windings consists of a weakly mobile non-resonant component which is presumably formed at the periphery due to ionization, and a component whose value and poloidal location are sensitive to resonance conditions for RF power absorption, this flow being apparently formed by a plasma diffusing through the LCMS and/or generated near the LCMS, where the filed E(sub r) is localized. Based on plasma parameters measurements after the RF pulse is switched off, a qualitative model of peripheral plasma dynamics after the end of the RF heating is constructed.

Besedin, N. T.; Chechkin, V. V.; Fomin, I. P.

272

Seasonal ultrastructural alterations in the plasma membrane produced by slow freezing in cortical tissues of mulberry ( Morus bombyciz Koidz. cv. Goroji)  

Microsoft Academic Search

Seasonal alterations in the ultrastructure of the plasma membrane produced by slow freezing were examined in cortical parenchyma cells of mulberry twigs (Morus bombyciz Koidz. cv. Goroji) grown in northern Japan. In freezing-sensitive summer, freezing produced distinct aparticulate domains with accompanying inverted hexagonalII (HII) phase transitions in the plasma membrane. In autumn and spring, during cold acclimation and deacclimation, freezing

Scizo Fujikawa

1994-01-01

273

Time-gated imaging with an ultrashort-pulse, laser-produced-plasma x-ray source  

NASA Astrophysics Data System (ADS)

We demonstrate a contrast improvement of nearly a factor of 5 in a phantom medical x-ray image, using time-gated detection. This improvement is accomplished by temporal discrimination against scattered x-ray flux and may permit a significant reduction in patient x-ray exposure. A multiterawatt ultrashort-pulse laser-produced-plasma x-ray source (<1 ps) and a time-gated microchannel plate detector ( \\similar 100 ps ) are used.

Gordon, C. L., III; Yin, G. Y.; Lemoff, B. E.; Bell, Perry M.; Barty, C. P. J.

1995-05-01

274

Fundamental Emission of Type III Bursts Produced in Non-Maxwellian Coronal Plasmas with Kappa-Distributed Background Particles  

NASA Astrophysics Data System (ADS)

Detailed simulations based on quasi-linear theory are presented for fundamental () emission of type III bursts produced in non-Maxwellian, suprathermal, background coronal plasma by injection of energetic electrons during flares with a power-law or Maxwellian velocity distribution, where is the electron plasma frequency. The background plasma is assumed to have a kappa ( ?) distribution, as inferred from solar wind data and proposed by theories for the corona and solar wind. The predicted type III beam speeds, Langmuir wave levels, and the drift rate and flux of emission are strongly sensitive to the presence of suprathermal background electrons in the corona. The simulations show the following results. i) Fast beams with speeds are produced for coronal background electrons with small ? ( ??5) by injected electrons with power-law spectra. ii) Moderately fast beams with are generated in coronal plasma with ??8 by injections of power-law or Maxwellian electrons. iii) Slow beams with are produced for coronal background electrons with large ? ( ?>8), including the asymptotic limit ??? where the electrons are Maxwellian, for both power-law and Maxwellian injections. The observation of fast type III beams (with ) thus suggests that these beams are produced in coronal regions where the background electron distribution has small ? by injected electrons with power-law spectra, at least when such beams are observed. The simulations, from the viewpoint of type III bursts, thus support: i) the presence, at least sometimes, of suprathermal background electrons in the corona and the associated mechanisms for coronal heating and solar wind acceleration; ii) power-law spectra for injected energetic electrons, consistent with observations of such electrons in situ and of X-ray emission.

Li, B.; Cairns, Iver H.

2014-03-01

275

Hard X-ray emission from laser-produced plasmas of U and Pb recorded by a transmission crystal spectrometer  

Microsoft Academic Search

Hard X-ray spectra from laser-produced plasmas were recorded by a transmission crystal survey spectrometer covering the 12–60keV energy range with a resolving power of E\\/?E?100. This emission is of interest for the development of hard X-ray backlighters and hot electron diagnostics. Foils of U and Pb were irradiated at the OMEGA laser facility by 24 beams (12 on each side),

J. F. Seely; R. Doron; A. Bar-Shalom; L. T. Hudson; C. Stoeckl

2003-01-01

276

NiAl–Al 2O 3 composites produced by pulse plasma sintering with the participation of the SHS reaction  

Microsoft Academic Search

The paper presents the results of examinations of the NiAl–Al2O3 sinters (13, 38 and 55vol% of Al2O3) produced from a mixture of nickel, aluminum and alumina powders in a single technological process, using the pulse plasma sintering (PPS) method. By subjecting the elemental powders to a PPS process for 900s, we obtained NiAl–Al2O3 composites of a hardness ranging from 480

A. Michalski; J. Jaroszewicz; M. Rosi?ski; D. Siemiaszko

2006-01-01

277

Infrared nanosecond laser-metal ablation in atmosphere: Initial plasma during laser pulse and further expansion  

SciTech Connect

We have investigated the dynamics of the nanosecond laser ablated plasma within and after the laser pulse irradiation using fast photography. A 1064 nm, 15 ns laser beam was focused onto a target made from various materials with an energy density in the order of J/mm{sup 2} in atmosphere. The plasma dynamics during the nanosecond laser pulse were observed, which could be divided into three stages: fast expansion, division into the primary plasma and the front plasma, and stagnation. After the laser terminated, a critical moment when the primary plasma expansion transited from the shock model to the drag model was resolved, and this phenomenon could be understood in terms of interactions between the primary and the front plasmas.

Wu, Jian; Wei, Wenfu; Li, Xingwen; Jia, Shenli; Qiu, Aici [State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Shaanxi 710049 (China)] [State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University, Shaanxi 710049 (China)

2013-04-22

278

Spatial coherence properties of a compact and ultrafast laser-produced plasma keV x-ray source  

SciTech Connect

The authors use Fresnel diffraction from knife-edges to demonstrate the spatial coherence of a tabletop ultrafast x-ray source produced by laser-plasma interaction. Spatial coherence is achieved in the far field by producing micrometer-scale x-ray spot dimensions. The results show an x-ray source size of 6 {mu}m that leads to a transversal coherence length of 20 {mu}m at a distance of 60 cm from the source. Moreover, they show that the source size is limited by the spatial spread of the absorbed laser energy.

Boschetto, D.; Mourou, G.; Rousse, A.; Mordovanakis, A.; Hou, Bixue; Nees, J.; Kumah, D.; Clarke, R. [Laboratoire d'Optique Appliquee, ENSTA-Ecole Polytechnique, Chemin de la Huniere, 91761 Palaiseau (France); FOCUS Center, University of Michigan, 2200 Banisteel Boulevard, Ann Arbor, Michigan 48109-2099 and Center for Ultrafast Optical Science, University of Michigan, 2200 Bonisteel Boulevard, Ann Arbor, Michigan 48109-2099 (United States); Applied Physics Program, University of Michigan, Ann Arbor, Michigan 48109-1040 (United States)

2007-01-01

279

Sweep Langmuir Probe and Triple Probe Diagnostics for Transient Plasma Produced by Hypervelocity Impact  

NASA Astrophysics Data System (ADS)

Two techniques are applied to diagnose characteristic parameters of plasma created by hypervelocity impact, such as electron temperature and electron density. The first technique is a sweep Langmuir probe (SLP), which is a new apparatus based on a dual channel circuit that can compensate for stray capacitance and obtain a good synchronicity, so that electrostatic turbulence with a good temporal resolution can be acquired. The second technique is a triple Langmuir probe (TLP), which is an electrostatic triple Langmuir probe diagnostic system, in which no voltage and frequency sweep is required. This technique allows to measure electron temperature, electron density as a function of time. Moreover, the triple Langmuir probe diagnostic system allows the direct display of electron temperature and semidirect display of electron density by an appropriate display system, the system permits us to eliminate almost all data processing procedures. SLP and TLP were applied to obtain fluctuations of the characteristic parameters of plasma generated by hypervelocity impact. As an example of their application to time-dependent plasma measurement, the electron temperature and electron density of plasmas were acquired in hypervelocity impact experiments. Characteristic parameters of plasma generated by hypervelocity impact were compared by the two kinds of diagnostic techniques mentioned above.

Tang, Enling; Xiang, Shenghai; Yang, Minghai; Li, Lexin

2012-08-01

280

Injection and acceleration of electron bunch in a plasma wakefield produced by a chirped laser pulse  

SciTech Connect

An ultrashort laser pulse propagating in plasma can excite a nonlinear plasma wakefield which can trap and accelerate charged particles up to GeV. One-dimensional analysis of electron injection, trapping, and acceleration by different chirped pulses propagating in plasma is investigated numerically. In this paper, we inject electron bunches in front of the chirped pulses. It is indicated that periodical chirped laser pulse can trap electrons earlier than other pulses. It is shown that periodical chirped laser pulses lead to decrease the minimum momentum necessary to trap the electrons. This is due to the fact that periodical chirped laser pulses are globally much efficient than nonchirped pulses in the wakefield generation. It is found that chirped laser pulses could lead to much larger electron energy than that of nonchirped pulses. Relative energy spread has a lower value in the case of periodical chirped laser pulses.

Afhami, Saeedeh; Eslami, Esmaeil, E-mail: eeslami@iust.ac.ir [Department of Physics, Iran University of Science and Technology (IUST), Narmak, Tehran 16846-13114 (Iran, Islamic Republic of)

2014-06-15

281

A Black-box Modelling Engine for Discharge Produced Plasma Radiation Sources  

SciTech Connect

A Blackbox Modelling Engine (BME), is an instrument based on the adaptation of the RMHD code Z*, integrated into a specific computation environment to provide a turn key simulation instrument and to enable routine plasma modelling without specialist knowledge in numerical computation. Two different operating modes are provided: Detailed Physics mode and Fast Numerics mode. In the Detailed Physics mode, non-stationary, non-equilibrium radiation physics have been introduced to allow the modelling of transient plasmas in experimental geometry. In the Fast Numerics mode, the system architecture and the radiation transport is simplified to significantly accelerate the computation rate. The Fast Numerics mode allows the BME to be used realistically in parametric scanning to explore complex physical set up, before using the Detailed Physics mode. As an example of the results from the BME modelling, the EUV source plasma dynamics in the pulsed capillary discharge are presented.

Zakharov, S.V.; Choi, P.; Krukovskiy, A.Y.; Zhang, Q. [EPPRA sas, 91961 Courtaboeuf (France); Novikov, V.G.; Zakharov, V.S. [KIAM RAS, 125047 Moscow (Russian Federation)

2006-01-05

282

INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: X-ray emission spectra of the plasma produced by an ultrashort laser pulse in cluster targets  

NASA Astrophysics Data System (ADS)

The first observation of x-ray emission spectra of multiply charged ions in the plasma produced by a 35-fs laser pulse with an intensity up to 1017 W cm-2 in CO2 and Kr gas jet targets is reported. The emission in the wavelength ranges of the 1snp—1s2(n=3-6) transitions of O VII ions and the Ly? line of O VIII ions, as well as of the (2s1/22p63p3/2)1—2s22p6 1S0 and (2s1/22p63p1/2)1—2s22p6 1S0 lines of Ne-like KrXXVII ions testifies that the highly ionised plasma is formed by collision processes in clusters. Modelling the shape of the spectral lines of oxygen ions by including the principal mechanisms of broadening and absorption in optically dense plasmas reveals that the main contribution to the time-integrated intensity is made by the plasma with the parameters Ne=(2-20)×1020 cm-3 and Te=100 — 115 eV.

Stenz, C.; Bagnoud, V.; Blasco, F.; Roche, J. R.; Salin, F.; Faenov, A. Ya; Magunov, A. I.; Pikuz, T. A.; Skobelev, I. Yu

2000-08-01

283

Plasma waves near Saturn: initial results from Voyager 1. Progress report  

SciTech Connect

The Voyager 1 plasma wave instrument detected many familiar types of plasma waves during the encounter with Saturn, including ion-acoustic waves and electron plasma oscillations upstream of the bow shock, an intense burst of electrostatic noise at the shock, and chorus, hiss, electrostatic (n + 1/2)fg waves and UHR emissions in the inner magnetosphere. A clock-like Saturn rotational control of low-frequency radio emissions was observed, and evidence was obtained of possible control by the moon Dione. Strong plasma wave emissions were detected at the Titan encounter indicating the presence of a turbulent sheath extending around Titan, and UHR measurements of the electron density show the existence of a dense plume of plasma being carried downstream of Titan by the interaction with the rapidly rotating magnetosphere of Saturn.

Gurnett, D.A.; Kurth, W.S.; Scarf, F.L.

1981-01-31

284

High-resolution imaging spectrometer for recording absolutely calibrated far ultraviolet spectra from laser-produced plasmas  

SciTech Connect

An imaging spectrometer was designed and fabricated for recording far ultraviolet spectra from laser-produced plasmas with wavelengths as short as 155 nm. The spectrometer implements a Cassegrain telescope and two gratings in a tandem Wadsworth optical configuration that provides diffraction limited resolution. Spectral images were recorded from plasmas produced by the irradiation of various target materials by intense KrF laser radiation with 248 nm wavelength. Two pairs of high-resolution gratings can be selected for the coverage of two wavebands, one grating pair with 1800 grooves/mm and covering approximately 155-175 nm and another grating pair with 1200 grooves/mm covering 230-260 nm. The latter waveband includes the 248 nm KrF laser wavelength, and the former waveband includes the wavelength of the two-plasmon decay instability at (2/3) the KrF laser wavelength (165 nm). The detection media consist of a complementary metal oxide semiconductor imager, photostimulable phosphor image plates, and a linear array of 1 mm{sup 2} square silicon photodiodes with 0.4 ns rise time. The telescope mirrors, spectrometer gratings, and 1 mm{sup 2} photodiode were calibrated using synchrotron radiation, and this enables the measurement of the absolute emission from the laser-produced plasmas with temporal, spatial, and spectral resolutions. The spectrometer is capable of measuring absolute spectral emissions at 165 nm wavelength as small as 5x10{sup -7} J/nm from a plasma source area of 0.37 mm{sup 2} and with 0.4 ns time resolution.

Brown, Charles M.; Seely, John F. [Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States); Feldman, Uri [ARTEP Inc., Ellicott City, Maryland 21042 (United States); Holland, Glenn E. [SFA Inc., 2200 Defense Highway, Suite 405, Crofton, Maryland 21114 (United States); Weaver, James L.; Obenschain, Steven P. [Plasma Physics Division, Naval Research Laboratory, Washington, DC 20375 (United States); Kjornrattanawanich, Benjawan [National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York 11973, USA and Universities Space Research Associates, Columbia, Maryland 21044 (United States); Fielding, Drew [Commonwealth Technologies Inc., 5775 Barclay Drive, Alexandria, Virginia 22315 (United States)

2008-10-15

285

Observation of Megagauss-Field Topology Changes due to Magnetic Reconnection in Laser-Produced Plasmas  

E-print Network

Center, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, USA R. P. J. Town and O. L reconnection physics in all regimes. In addition, the methodology is quite general and is appli- cable,18]. It follows that the ratio of thermal pressure to field pressure was #12; 1, indicating that plasma motion

286

Rheological characterization of a gel produced using human blood plasma and alginate mixtures.  

PubMed

Human blood plasma is a material used to generate tissue equivalents due to presence of fibrinogen. However, gels formed using human blood plasma has weak mechanical properties. In this study, different mixtures of sodium alginate and blood plasma were performed and evaluated. By determining ? potential can be established the stability of the plasma-alginate mixture and by dynamic rheology can determine the most suitable parameters for the gelation of the above mixtures, when calcium chloride is used as a crosslinker. Experimental results evidence an increment in ? potential at alginate concentrations of 0.8% and 1.6% with a resulting pseudoplastic behavior of evaluated mixtures, which described the homogenization of the mixture. On the other hand, mixtures were gelled by using aspersion of calcium chloride and characterized by dynamic rheology. Solid behavior is dominant in all range of frequency sweep test between 0.1Hz and 100Hz. Finally, the ultimate tensile strength of a gel reach 6.36938±0.24320kPa, which is enough for manual handling of the gel. Between the tasks of the gel would be used for cell entrapment, for controlled release of drugs or in the manufacture of wound dressings. PMID:24603213

Malagón-Romero, Dionisio; Hernández, Nicolás; Cardozo, Carmen; Godoy-Silva, Rubén D

2014-06-01

287

Guiding of terawatt laser pulses in a plasma waveguide produced in an elongated pulsed gas jet  

Microsoft Academic Search

We have recently demonstrated a high repetition rate gas jet, designed to eliminate the problem of refraction in the injection of high intensity laser pulses into plasma waveguides. A sequence of measured electron density from a 1.5 cm long argon jet waveguide is shown. We show electron density profiles as a function of axial distance at the end of the

I. Alexeev; S. Nikitin; I. Fan; H. M. Milchberg

1999-01-01

288

The diagnostics of ultra-short pulse laser-produced plasma  

Microsoft Academic Search

Since the invention of the laser, coherent light has been used to break down solid or gaseous material and transform it into a plasma. Over the last three decades two things have changed. Due to multiple advancements and design of high power lasers it is now possible to increase the electric and magnetic field strength that pushed the electron motion

Markus Roth

2011-01-01

289

INTEGRATED SIMULATION OF DISCHARGE AND LASER PRODUCED PLASMAS IN EUV LITHOGRAPHY DEVICES  

E-print Network

of several main tasks: plasma evolution and magnetohydrodynamic (MHD) processes; detailed photon radiation efficiency of laser light into soft X-rays within a 2% bandwidth at 13.5 nm, where multilayer reflectivity, device design, etc. In this work, we present our simulation model of the MHD and optical processes

Harilal, S. S.

290

Dynamical behavior of higher harmonic generation from a picosecond laser produced solid surface plasma  

Microsoft Academic Search

We have investigated the efficiency of the fifth order harmonics from solid surface plasma by varying the electron density gradient using two 2.2 ps, 1054 nm laser pulses. A 5 ps time difference between the prepulse and main pulse results in an increase in the harmonic signal by a factor of 2–3, which then decreases for time delays greater than

A. Ishizawa; T. Kanai; T. Ozaki; H. Kuroda

2000-01-01

291

Supersonic Ionization Wave Driven by Radiation Transport in a Short-Pulse Laser-Produced Plasma  

Microsoft Academic Search

Through the use of an ultrashort (2ps) optical probe, we have time resolved the propagation of an ionization wave into solid fused silica. This ionization wave results when a plasma is created by the intense irradiation of a solid target with a 2ps laser pulse. We find that the velocity of the ionization wave is consistent with radiation driven thermal

T. Ditmire; E. T. Gumbrell; R. A. Smith; L. Mountford; M. H. Hutchinson

1996-01-01

292

Different approaches to produce coatings with bioactive glasses: Enamelling vs plasma spraying  

Microsoft Academic Search

Two alternative approaches, enamelling and plasma spraying, were tested to deposit coatings made with two different bioactive glasses: the established Bioglass® 45S5, which is considered as a term of comparison, and the experimental BioK. The strong points and weaknesses of the two methods were highlighted. From the analysed samples, it resulted that the enamelling approach works well on thermally stable

V. Cannillo; A. Sola

2010-01-01

293

Multiple solutions in the theory of direct current glow discharges: Effect of plasma chemistry and nonlocality, different plasma-producing gases, and 3D modelling  

NASA Astrophysics Data System (ADS)

The work is aimed at advancing the multiple steady-state solutions that have been found recently in the theory of direct current (DC) glow discharges. It is shown that an account of detailed plasma chemistry and non-locality of electron transport and kinetic coefficients results in an increase of the number of multiple solutions but does not change their pattern. Multiple solutions are shown to exist for discharges in argon and helium provided that discharge pressure is high enough. This result indicates that self-organization in DC glow microdischarges can be observed not only in xenon, which has been the case until recently, but also in other plasma-producing gases; a conclusion that has been confirmed by recent experiments. Existence of secondary bifurcations can explain why patterns of spots grouped in concentric rings, observed in the experiment, possess in many cases higher number of spots in outer rings than in inner ones.

Almeida, P. G. C.; Benilov, M. S.

2013-10-01

294

Multiple solutions in the theory of direct current glow discharges: Effect of plasma chemistry and nonlocality, different plasma-producing gases, and 3D modelling  

SciTech Connect

The work is aimed at advancing the multiple steady-state solutions that have been found recently in the theory of direct current (DC) glow discharges. It is shown that an account of detailed plasma chemistry and non-locality of electron transport and kinetic coefficients results in an increase of the number of multiple solutions but does not change their pattern. Multiple solutions are shown to exist for discharges in argon and helium provided that discharge pressure is high enough. This result indicates that self-organization in DC glow microdischarges can be observed not only in xenon, which has been the case until recently, but also in other plasma-producing gases; a conclusion that has been confirmed by recent experiments. Existence of secondary bifurcations can explain why patterns of spots grouped in concentric rings, observed in the experiment, possess in many cases higher number of spots in outer rings than in inner ones.

Almeida, P. G. C.; Benilov, M. S. [Departamento de Física, CCCEE, Universidade da Madeira, Largo do Município, 9000 Funchal (Portugal)] [Departamento de Física, CCCEE, Universidade da Madeira, Largo do Município, 9000 Funchal (Portugal)

2013-10-15

295

Experimental observation of left polarized wave absorption near electron cyclotron resonance frequency in helicon antenna produced plasma  

SciTech Connect

Asymmetry in density peaks on either side of an m = +1 half helical antenna is observed both in terms of peak position and its magnitude with respect to magnetic field variation in a linear helicon plasma device [Barada et al., Rev. Sci. Instrum. 83, 063501 (2012)]. The plasma is produced by powering the m = +1 half helical antenna with a 2.5 kW, 13.56 MHz radio frequency source. During low magnetic field (B < 100 G) operation, plasma density peaks are observed at critical magnetic fields on either side of the antenna. However, the density peaks occurred at different critical magnetic fields on both sides of antenna. Depending upon the direction of the magnetic field, in the m = +1 propagation side, the main density peak has been observed around 30 G of magnetic field. On this side, the density peak around 5 G corresponding to electron cyclotron resonance (ECR) is not very pronounced, whereas in the m = -1 propagation side, very pronounced ECR peak has been observed around 5 G. Another prominent density peak around 12 G has also been observed in m = -1 side. However, no peak has been observed around 30 G on this m = -1 side. This asymmetry in the results on both sides is explained on the basis of polarization reversal of left hand polarized waves to right hand polarized waves and vice versa in a bounded plasma system. The density peaking phenomena are likely to be caused by obliquely propagating helicon waves at the resonance cone boundary.

Barada, Kshitish K.; Chattopadhyay, P. K.; Ghosh, J.; Kumar, Sunil; Saxena, Y. C. [Institute for Plasma Research, Bhat, Gandhinagar 382428 (India)

2013-01-15

296

K-shell emission from 140 femtosecond laser-produced plasmas created from porous aluminum targets  

Microsoft Academic Search

The K-shell emission from flat and porous aluminum targets is used to infer the efficiency of creating a high temperature (>100eV), thermal plasma with 800 nm, 140 fs laser light. The K-shell emission from flat aluminum targets is fond to be significantly less than that of the porous targets, implying a lower temperature and less efficient coupling between the target

R. Shepherd; D. Price; B. White; A. Osterheld; R. Walling; D. Slaughter; R. Stewart; S. Gordan

1992-01-01

297

Data elaboration of proton beams produced by high-energy laser-generated plasmas  

Microsoft Academic Search

The proton beam production from high-energy laser-generated plasma is increasingly becoming of special interest for investigations in the field of new techniques of ion acceleration, nuclear physics, astrophysics and radiotherapy. The evolution of short-pulsed lasers, from the nanosecond to the femtosecond pulse scale, has allowed for an increase in intensity from about 10 W\\/cm to about 10 W\\/cm with a consequent increase

L. Torrisi; T. Minniti; L. Giuffrida

2010-01-01

298

An in vitro investigation of plasma sprayed hydroxyapatite (HA) coatings produced with flame-spheroidized feedstock  

Microsoft Academic Search

The in vitro behaviour and characteristics of plasma sprayed hydroxyapatite (HA) coatings using flame-spheroidized HA feedstock powder on titanium alloy (Ti-6Al-4V) substrates were investigated in a simulated physiological environment as an attempt to reflect the actual incubational condition of an implant in a human body system. As-sprayed and heat-treated HA coatings were immersed in a simulated body fluid with ionic

S. W. K Kweh; K. A Khor; P Cheang

2002-01-01

299

Expansion Dynamics of Ultrafast Laser Produced Plasmas in the Presence of Ambient Argon  

SciTech Connect

In this paper, we report the emission features of fs laser ablated brass plasma plumes at various Ar background pressure levels ranging from vacuum to atmospheric conditions. Spectrally integrated 2D-imaging of plasma self-emission showed several interesting features at various pressure levels which consists of plume morphological changes, increase in persistence, confinement, and internal structures. Spatially resolved wavelength dispersed images of the plume were recorded for characterizing the spectral features at various pressure levels and also used for obtaining spatial distribution of Cu I and Zn I species in the plume, signal to noise ratios and fundamental parameters of the plasma; viz. temperature and density. The spatial evolution of excitation temperature and density showed significant changes at various ambient pressure levels and these results were correlated to morphological changes seen in the plume images. Optimum signal to background ratios for emission lines were observed in the moderate pressure range (~ 1-10 Torr). Optical time-of-flight profiles were used to study time evolution of various species in the plume and noticed oscillations at intermediate pressure levels. Possible mechanisms for observed changes in plume shape, optical emission intensity, and dual peak structures in time-of-flight profiles were discussed.

Diwakar, P. K.; Harilal, Sivanandan S.; Hassanein, A.; Phillips, Mark C.

2014-10-07

300

Study of self-generated magnetic fields in laser produced plasmas using a three-channel polaro-interferometer  

SciTech Connect

Self-generated magnetic fields produced in laser plasmas at moderate laser intensities have been measured using a three-channel polaro-interferometer. The main elements of this device are two birefringent calcite wedges placed between two crossed polarizers. Using this device, the spatial profiles of (a) the rotation angle (polarometry), (b) the electron density (interferometry), and (c) the transmitted probe beam intensity (shadowgraphy) are recorded simultaneously using a digital camera with a large format CCD in a single laser shot. Magnetic fields of 2-4 MG had been estimated in aluminum plasma at laser intensities {approx}10{sup 13} W/cm{sup 2}. It is also possible to use this device in other configurations to get time resolved information.

Prasad, Y. B. S. R.; Barnwal, S.; Naik, P. A.; Kamath, M. P.; Joshi, A. S.; Kumbhare, S. R.; Gupta, P. D. [Laser Plasma Division, Raja Ramanna Centre for Advanced Technology, Indore 452013 (India); Bolkhovitinov, E. A.; Rupasov, A. A. [Laboratory of Plasma Diagnostics, P.N. Lebedev Physical Institute, 53 Leninsky Prospekt, Moscow 117924 (Russian Federation)

2011-12-15

301

Study of self-generated magnetic fields in laser produced plasmas using a three-channel polaro-interferometer.  

PubMed

Self-generated magnetic fields produced in laser plasmas at moderate laser intensities have been measured using a three-channel polaro-interferometer. The main elements of this device are two birefringent calcite wedges placed between two crossed polarizers. Using this device, the spatial profiles of (a) the rotation angle (polarometry), (b) the electron density (interferometry), and (c) the transmitted probe beam intensity (shadowgraphy) are recorded simultaneously using a digital camera with a large format CCD in a single laser shot. Magnetic fields of 2-4 MG had been estimated in aluminum plasma at laser intensities ~10(13) W/cm(2). It is also possible to use this device in other configurations to get time resolved information. PMID:22225217

Prasad, Y B S R; Barnwal, S; Bolkhovitinov, E A; Naik, P A; Kamath, M P; Joshi, A S; Kumbhare, S R; Rupasov, A A; Gupta, P D

2011-12-01

302

Neutron Emission Characteristics of a High-Current Plasma Focus: Initial Studies  

SciTech Connect

The Texas A and M University plasma focus machine is operational and is beginning to provide good experimental data. It has its origins in several earlier machines and is located in a former service station building with a shield wall that provides a good geometry for neutron measurements. We are operating in the high pressure mode for a plasma focus, similar to previous efforts in the US. Early neutron measurements are providing some insight for the machine's operation.

L. H. Ziegler; B. L. Freeman; J. C. Boydston

2002-06-01

303

Initial Operation of the Miniaturized Inductively Heated Plasma Generator IPG6  

NASA Astrophysics Data System (ADS)

In close collaboration between the Center for Astrophysics, Space Physics and Engineering Research (CASPER) at Baylor University, Texas, and the Institute of Space Systems (IRS) at the University of Stuttgart, Germany, two plasma wind tunnel facilities of similar type have been established using the inductively heated plasma source IPG6 which is based on proven IRS designs. The facility at Baylor University (IPG6-B) works at a frequency of 13.56 MHz and a maximum power of 15 kW. A vacuum pump of 160m^3/h in combination with a butterfly valve allows pressure control in a wide range. First experiments have been conducted with Air, O2 and N2 as working gases and volumetric flow rates of up to 14 L/min at pressures of a few 100 Pa, although pressures below 1 Pa are achievable at lower flow rates. The maximum tested electric power so far was 8 kW. Plasma powers and total pressures in the plasma jet have been obtained. In the near future the set up of additional diagnostics, the use of other gases (i.e. H2, He), and the integration of a dust particle accelerator are planned. The intended fields of research are basic investigation in thermo-chemistry and plasma radiation, space plasma environments and high heat fluxes e.g. in fusion devices or during atmospheric entry of spacecraft.

Dropmann, Michael; Herdrich, Georg; Laufer, Rene; Koch, Helmut; Gomringer, Chris; Cook, Mike; Schmoke, Jimmy; Matthews, Lorin; Hyde, Truell

2012-10-01

304

Photoconductive Detectors with Fast Temporal Response for Laser Produced Plasma Experiments.  

SciTech Connect

Processes during laser plasma experiments typically have time scales that are less than 100 ps. The measurement of these processes requires X-ray detectors with fast temporal resolution. We have measured the temporal responses and linearity of several different X-ray sensitive Photoconductive Detectors (PCDs). The active elements of the detectors investigated include both diamond (natural and synthetic) and GaAs crystals. The typical time responses of the GaAs PCDs are approximately 60 ps, respectively. Some characterizations using X-ray light from a synchrotron light source are presented.

May, M; Halvorson, C; Perry, T; Weber, F; Young, P; Silbernagel, C

2008-05-06

305

Photoconductive Detectors with Fast Temporal Response for Laser Produced Plasma Experiments  

SciTech Connect

Processes during laser plasma experiments typically have time scales that are less than 100 ps. The measurement of these processes requires X-ray detectors with fast temporal resolution. We have measured the temporal responses and linearity of several different Xray sensitive Photoconductive Detectors (PCDs). The active elements of the detectors investigated include both diamond (natural and synthetic) and GaAs crystals. The typical time responses of the GaAs PCDs are approximately 60 ps, respectively. Some characterizations using X-ray light from a synchrotron light source are presented.

M. J. May, C. Halvorson, T. Perry, F. Weber, P. Young, C. Silbernagel

2008-06-01

306

Photoconductive detectors with fast temporal response for laser produced plasma experiments  

SciTech Connect

Processes during laser plasma experiments typically have time scales that are less than 100 ps. The measurement of these processes requires x-ray detectors with fast temporal resolution. We have measured the temporal responses and linearity of several different x-ray sensitive photoconductive detectors (PCDs). The active elements of the detectors investigated include both diamond (natural and synthetic) and GaAs crystals. The typical time responses of the GaAs PCDs are approximately 60 ps, respectively. Some characterizations using x-ray radiation from a synchrotron radiation source are presented.

May, M. J.; Halvorson, C.; Perry, T.; Weber, F.; Young, P. [Lawrence Livermore National Laboratory, 7000 East Ave., Livermore, California 94550 (United States); Silbernagel, C. [National Security Technologies LLC, P.O. Box 2710, Livermore, California 94550 (United States)

2008-10-15

307

Direct observation of high-speed plasma outflows produced by magnetic reconnection in solar impulsive events  

E-print Network

Spectroscopic observations of a solar limb flare recorded by SUMER on SOHO reveal, for the first time, hot fast magnetic reconnection outflows in the corona. As the reconnection site rises across the SUMER spectrometer slit, significant blue- and red-shift signatures are observed in sequence in the Fe XIX line, reflecting upflows and downflows of hot plasma jets, respectively. With the projection effect corrected, the measured outflow speed is between 900-3500 km/s, consistent with theoretical predictions of the Alfvenic outflows in magnetic reconnection region in solar impulsive events. Based on theoretic models, the magnetic field strength near the reconnection region is estimated to be 19-37 Gauss.

Tongjiang Wang; Linhui Sui; Jiong Qiu

2007-09-14

308

Processes for forming exoergic structures with the use of a plasma and for producing dense refractory bodies of arbitrary shape therefrom  

DOEpatents

Plasma spraying methods of forming exoergic structures and coatings, as well as exoergic structures produced by such methods, are provided. The methods include the plasma spraying of reactive exoergic materials that are capable of sustaining a combustion synthesis reaction onto a flat substrate or into molds of arbitrary shape and igniting said plasma sprayed materials, either under an inert gas pressure or not, to form refractory materials of varying densities and of varying shapes.

Holt, J. Birch (San Jose, CA); Kelly, Michael D. (West Alexandria, OH)

1990-01-01

309

Atmospheric Pressure Plasma Jet in Organic Solution: Spectra, Degradation Effects of Solution Flow Rate and Initial pH Value  

NASA Astrophysics Data System (ADS)

The organic compounds of p-nitrophenol (PNP) solution was treated by the active species generated in a stirred reactor by an atmospheric pressure plasma jet (APPJ). The emission intensities of hydroxyl (OH), oxygen (O), nitric oxide (NO), hydrogen (H) and molecular (N2) were measured by optical emission spectroscopy (OES). The relations between the flow rates of the PNP solution and degradation, the degradation effects and initial pH value of the solution were also investigated. Experimental results show that there exist intense emissions of O (777.1 nm), N2 (337.1 nm), OH (306–310 nm) and NO band (200–290 nm) in the region of plasma. Given the treatment time and gas flow rate, the degradation increased as a function of discharge energy and solution flow rate, respectively. The solution flow rate for the most efficient degradation ranged from 1.414 m/s to 1.702 m/s, and contributed very little when it exceeded 2.199 m/s. This indicates the existence of diffusion-controlled reactions at a low solution flow rate and activation-controlled reactions at a high solution flow rate. Moreover, increasing or decreasing the initial pH value of neutral PNP solution (pH=5.95) could improve the degradation efficiency. Treated by APPJ, the PNP solutions with different initial pH values of 5.95, 7.47 and 2.78 turned more acidic in the end, while the neutral solution had the lowest degradation efficiency. This work clearly demonstrates the close coupling of active species, photolysis of ultraviolet, the organic solution flow rate and the initial pH value, and thus is helpful in the study of the mechanism and application of plasma in wastewater treatment.

Chen, Bingyan; Zhu, Changping; Chen, Longwei; Fei, Juntao; Gao, Ying; Wen, Wen; Shan, Minglei; Ren, Zhaoxing

2014-12-01

310

Plasma-produced phase-pure cuprous oxide nanowires for methane gas sensing  

SciTech Connect

Phase-selective synthesis of copper oxide nanowires is warranted by several applications, yet it remains challenging because of the narrow windows of the suitable temperature and precursor gas composition in thermal processes. Here, we report on the room-temperature synthesis of small-diameter, large-area, uniform, and phase-pure Cu{sub 2}O nanowires by exposing copper films to a custom-designed low-pressure, thermally non-equilibrium, high-density (typically, the electron number density is in the range of 10{sup 11}–10{sup 13}?cm{sup ?3}) inductively coupled plasmas. The mechanism of the plasma-enabled phase selectivity is proposed. The gas sensors based on the synthesized Cu{sub 2}O nanowires feature fast response and recovery for the low-temperature (?140?°C) detection of methane gas in comparison with polycrystalline Cu{sub 2}O thin film-based gas sensors. Specifically, at a methane concentration of 4%, the response and the recovery times of the Cu{sub 2}O nanowire-based gas sensors are 125 and 147?s, respectively. The Cu{sub 2}O nanowire-based gas sensors have a potential for applications in the environmental monitoring, chemical industry, mining industry, and several other emerging areas.

Cheng, Qijin, E-mail: ijin.cheng@xmu.edu.cn; Zhang, Fengyan [School of Energy Research, Xiamen University, Xiamen City, Fujian Province 361005 (China); Yan, Wei [School of Electrical Engineering and Telecommunications, University of New South Wales, Sydney, New South Wales 2052 (Australia); Plasma Nanoscience Laboratories, CSIRO Materials Science and Engineering, Lindfield, New South Wales 2070 (Australia); Randeniya, Lakshman [Plasma Nanoscience Laboratories, CSIRO Materials Science and Engineering, Lindfield, New South Wales 2070 (Australia); Ostrikov, Kostya [Plasma Nanoscience Laboratories, CSIRO Materials Science and Engineering, Lindfield, New South Wales 2070 (Australia); Plasma Nanoscience, School of Physics, The University of Sydney, Sydney, New South Wales 2006 (Australia)

2014-03-28

311

Radio-Frequency Sustainment of Laser Initiated, High-Pressure Air Constituent Plasmas  

NASA Astrophysics Data System (ADS)

In this paper we investigate the feasibility of creating a high-density ˜ 1012-1014 cm-3, large volume seed plasma in air constituents by laser (300 mJ, 20(±2) ns) preionization of an organic gas seeded in high-pressure gas mixtures and then sustained by efficient absorption of rf power (1-25 kW pulsed) through inductive coupling of the wave fields. A multi-turn helical antenna is used to couple radio-frequency power through a capacitive matching network. A 105 GHz interferometer is employed to obtain the plasma density in the presence of high collisionality utilizing phase shift and amplitude attenuation data. TMAE Plasma decay mechanisms with and without the background gas are examined.

Akhtar, Kamran; Scharer, John E.; Tysk, Shane M.; Denning, Mark

2003-12-01

312

INTERACTION OF LASER RADIATION WITH MATTER. LASER PLASMA: Quasi-stationary magnetic and electric waves produced by a pulsed shock-wave source  

NASA Astrophysics Data System (ADS)

A merging mechanism of shock waves in a plasma with a magnetic field is considered. The merging criterion is found at which a point source produces low-frequency waves of magnetic and vortex electric fields in the surroundings.

Tishchenko, V. N.; Shaikhislamov, I. F.

2006-01-01

313

Biostability of Batracylin: Incubation of batracylin in mouse and human plasma for as long as 48 h did not produce significant degradation  

Cancer.gov

Batracyclin Pharmacology Abstract Division of Cancer Treatment and Diagnosis National Cancer Institute Biostability of Batracylin: Incubation of batracylin in mouse and human plasma for as long as 48 h did not produce significant degradation.

314

Microstructural, mechanical and oxidation features of NiCoCrAlY coating produced by plasma activated EB-PVD  

NASA Astrophysics Data System (ADS)

NiCoCrAlY coatings produced by electron beam-physical vapor deposition (EB-PVD) have been extensively used as the oxidation resistance coatings or suitable bond coats in thermal barrier coating (TBC) system. However, the inherent imperfections caused by EB-PVD process degrade the oxidation resistance of the coatings. In the present work, NiCoCrAlY coatings were creatively produced by plasma activated electron beam-physical vapor deposition (PA EB-PVD). The novel coatings showed a terraced substructure on the surface of each grain due to the increased energy of metal ions and enhanced mobility of adatoms. Also a strong (1 1 1) crystallographic texture of ?/?' grains was observed. The toughness of the coatings got remarkably improved compared with the coatings deposited by conventional EB-PVD and the oxidation behavior at 1373 K showed that the novel coatings had excellent oxidation resistance. The possible mechanism was finally discussed.

He, Jian; Guo, Hongbo; Peng, Hui; Gong, Shengkai

2013-06-01

315

Natural IgM Is Produced by CD5- Plasma Cells That Occupy a Distinct Survival Niche in Bone Marrow.  

PubMed

Natural IgM is constitutively present in the serum, where it aids in the early control of viral and bacterial expansions. Natural IgM also plays a significant role in the prevention of autoimmune disease by promoting the clearance of cellular debris. Nevertheless, the origins of natural IgM have not been precisely defined. Previous studies focused on the role of CD5(+) B1 cells in the production of natural IgM, but we show in this article that a discrete population of CD5(-) IgM plasmablasts and plasma cells in the bone marrow (BM) produces the majority of serum IgM in resting mice. These Ab-secreting cells (ASC) originate from peritoneal cavity-resident cells, because transfer of peritoneal cells completely restores serum IgM and the specific compartment of BM ASC in Rag1-deficient mice. We show that BM natural IgM ASC arise from a fetal-lineage progenitor that is neither B1a nor B1b, and that this IgM ASC compartment contains a substantial fraction of long-lived plasma cells that do not occupy the IgG plasma cell survival niche in the BM; instead, they are supported by IL-5. In summary, we identified the primary source of natural IgM and showed that these ASC are maintained long-term in a unique survival niche within the BM. PMID:25429072

Reynolds, Alexander E; Kuraoka, Masayuki; Kelsoe, Garnett

2015-01-01

316

Formation of hot spots in the plasma of a Z-pinch produced from low-density deuterated polyethylene  

NASA Astrophysics Data System (ADS)

Results are presented from experimental studies of the plasma formation dynamics in a Z-pinch produced from a cylindrical microporous agar-agar load. The experiments were performed on the S-300 facility at a current of 2 MA and current rise time of 100 ns. To enhance the energy concentration, a deuterated polyethylene neck with a mass density of 50-75 ?g/cm3 and diameter of 1-2 mm was made in the central part of the load. The spatiotemporal characteristics of the Z-pinch were studied using an optical streak camera and fast frame photography in the optical and soft X-ray spectral ranges. X-ray emission was detected using semiconductor and vacuum diodes, and neutron emission was studied by means of the time-of-flight method. It is found that, in the course of continuous plasma production, hot spots with a diameter of 100 ?m form in the pinch plasma. The hot spots emit short soft X-ray pulses with a duration of 2-4 ns, as well as neutron pulses with an average neutron energy of about 2.45 MeV. The maximum neutron yield was found to be 4.5 × 109 neutrons per shot. The scenario of hot spot formation is adequately described by two-dimensional MHD simulations.

Akunets, A. A.; Anan'ev, S. S.; Bakshaev, Yu. L.; Blinov, P. I.; Bryzgunov, V. A.; Vikhrev, V. V.; Volobuev, I. V.; Dan'ko, S. A.; Zelenin, A. A.; Kazakov, E. D.; Korolev, V. D.; Meshcherov, B. R.; Nedoseev, S. L.; Pimenov, V. G.; Smirnova, E. A.; Ustroev, G. I.; Chernenko, A. S.; Shchagin, V. A.

2010-08-01

317

High resolution soft x-ray spectroscopy of low Z K-shell emission from laser-produced plasmas  

SciTech Connect

A large radius, R = 44.3 m, High Resolution Grating Spectrometer (HRGS) with 2400 line/mm variable line spacing has been designed for laser-produced plasma experiments conducted at the Lawrence Livermore National Laboratory Jupiter Laser Facility. The instrument has been run with a low-noise, charge-coupled device detector to record high signal-to-noise spectra in the 10-50 {angstrom} wavelength range. The instrument can be run with a 10-20 {micro}m wide slit to achieve the best spectral resolving power, approaching 1000 and similar to crystal spectrometers at 12-20 {angstrom}, or in slitless operation with a small symmetrical emission source. We describe preliminary spectra emitted from various H-like and He-like low Z ion plasmas heated by 100-500 ps (FWHM), 527 nm wavelength laser pulses. This instrument can be developed as a useful spectroscopy platform relevant to laboratory-based astrophysics as well as high energy density plasma studies.

Dunn, J; Magee, E W; Shepherd, R; Chen, H; Hansen, S B; Moon, S J; Brown, G V; Gu, M; Beiersdorfer, P; Purvis, M A

2008-05-21

318

Optical observations of post-discharge phenomena of laser-triggered discharge produced plasma for EUV lithography  

NASA Astrophysics Data System (ADS)

This paper reports the dynamic post-discharge phenomena of laser-triggered discharge-produced plasmas (LTDPP) for extreme ultraviolet lithography (EUVL) sources. A pulsed laser was focused on the high-voltage tin cathode surface to form tin vapor jet across a 5 mm long anode–cathode gap, which leads to the electrical breakdown. The post-discharge phenomena were observed using both of the Schlieren method and high-speed camera. Schlieren images show the dynamic evolution of the discharge plasma and the development of tin droplets. Visible emission from the plasma lasted for more than 1 µs after the current stopped. The droplets emerged from the cathode approximately 100 µs after discharge and spread throughout the electrodes gap. Various sizes of droplets stagnate in the gap for milliseconds. The subsequent laser pulse and voltage application show an interaction between the droplets and the subsequent discharge. The subsequent laser pulse evaporates not only the cathode surface but also the droplets, which influence the tin vapor distribution in the gap. This uncertain vapor distribution affects the formation process of microplasmas that emit EUV.

Lim, Soowon; Kitajima, Seiya; Lu, Peng; Sakugawa, Takashi; Akiyama, Hidenori; Katsuki, Sunao; Teramoto, Yusuke

2015-01-01

319

New method to produce equine antirabies immunoglobulin F(ab')? fragments from crude plasma in high quality and yield.  

PubMed

Rabies is still a major cause of human deaths in several developing countries. According to the World Health Organization, administration of antirabies serum or antirabies immunoglobulin is recommended for patients who have experienced a category-III exposure to rabies. Improvement of antirabies immunoglobulin production is required to enhance safety and efficacy of the products. In this paper, a new method to produce equine antirabies immunoglobulin F(ab')(2) fragments from crude plasma is proposed. First, protein G affinity chromatography was used to purify IgG from equine plasma. Moreover, purification of IgG was shown to facilitate its digestion by pepsin. Compared to the direct digestion of crude plasma, a lower amount of pepsin and a shorter digestion time were required to completely digest the purified IgG to F(ab')(2). Complete digestion of purified IgG to F(ab')(2) was achieved at a pepsin/IgG (w/w) ratio of 5:45 with preservation of structure and potency. Finally, purification of F(ab')(2) was accomplished by a combination of protein A affinity chromatography and ultrafiltration with a 50-kDa nominal molecular weight cut-off membrane. The new process resulted in 68.9±0.6 (%) total recovery of F(ab')(2) and a F(ab')(2) product of high potency. PMID:21414404

Kittipongwarakarn, Sukanda; Hawe, Andrea; Tantipolphan, Ruedeeporn; Limsuwun, Kornvika; Khomvilai, Sumana; Puttipipatkhachorn, Satit; Jiskoot, Wim

2011-06-01

320

Diamond-like carbon produced by plasma source ion implantation as a corrosion barrier  

Microsoft Academic Search

There currently exists a broad range of applications for which the ability to produce an adherent, hard, wear and, corrosion-resistant coating plays a vital role. These applications include engine components, orthopedic devices, textile manufacturing components, hard disk media, optical coatings, and cutting and machining tools (e.g., punches, taps, scoring dies, and extrusion dies). Ion beam processing can play an important

R. S. Lillard; D. P. Butt; T. N. Taylor; K. C. Walter; M. Nastasi

1998-01-01

321

System to continuously produce carbon fiber via microwave assisted plasma processing  

DOEpatents

A method for continuously processing carbon fiber including establishing a microwave plasma in a selected atmosphere contained in an elongated chamber having a microwave power gradient along its length defined by a lower microwave power at one end and a higher microwave power at the opposite end of the elongated chamber. The elongated chamber having an opening in each of the ends of the chamber that are adapted to allow the passage of the fiber tow while limiting incidental gas flow into or out of said chamber. A continuous fiber tow is introduced into the end of the chamber having the lower microwave power. The fiber tow is withdrawn from the opposite end of the chamber having the higher microwave power. The fiber to is subjected to progressively higher microwave energy as the fiber is being traversed through the elongated chamber.

White, Terry L; Paulauskas, Felix L; Bigelow, Timothy S

2014-03-25

322

Signature of superradiance from a nitrogen gas plasma channel produced by strong field ionization  

E-print Network

Recently, Yao et al. demonstrated the creation of coherent emissions in nitrogen gas with two-color (800 nm + 400 nm) ultrafast laser pulses [New J. Phys. 15, 023046 (2013)]. Based on this two-color scheme, here we report on systematic investigation of temporal characteristics of the coherent emission at 391 nm by experimentally examining its evolution with the increase of the plasma channel induced by the intense 800 nm femtosecond laser pulses at a nitrogen gas pressure of ~25 mbar. We reveal unexpected temporal profiles of the coherent emissions, which show significant superradiance signatures owing to the quantum coherence via cooperation of an ensemble of excited N2+ molecules. Our findings shed more light on the mechanisms behind the laser-like emissions induced by strong-field ionization of molecules.

Li, Guihua; Zeng, Bin; Xie, Hongqiang; Yao, Jinping; Chu, Wei; Ni, Jielei; Zhang, Haisu; Xu, Huailiang; Cheng, Ya; Xu, Zhizhan

2013-01-01

323

A source mechanism producing HF-induced plasma lines (HFPLS) with up-shifted frequencies  

NASA Technical Reports Server (NTRS)

Attention is given to a nonlinear scattering process analyzed as a source mechanism producing the frequency up-shifted HFPLs observed in the Arecibo ionospheric heating experiments. A physical picture is offered to explain how Langmuir waves with frequencies greater than the HF heater wave frequency can be produced in the heating experiments and be detected by incoherent radars as frequency up-shifted HFPLs. Since the considered scattering process occurs in a region near the reflection height, it explains why the frequency up-shifted HFPLs should originate from the altitude near the reflection height as observed. The theory also shows that the amount of frequency up-shift is inversely proportional to the frequency of the HF heater and increases linearly with the electron temperature. The quantitative analysis of the theory shows a good agreement with the experimental results.

Kuo, S. P.; Lee, M. C.

1992-01-01

324

Filamentary structure of plasma produced by compression of puffing deuterium by deuterium or neon plasma sheath on plasma-focus discharge  

NASA Astrophysics Data System (ADS)

The present experiments were performed on the PF-1000 plasma focus device at a current of 2 MA with the deuterium injected from the gas-puff placed in the axis of the anode face. The XUV frames showed, in contrast with the interferograms, the fine structure: filaments and spots up to 1 mm diameter. In the deuterium filling, the short filaments are registered mainly in the region of the internal plasmoidal structures and their number correlates with the intensity of neutron production. The longer filamentary structure was recorded close to the anode after the constriction decay. The long curve-like filaments with spots were registered in the big bubble formed after the pinch phase in the head of the umbrella shape of the plasma sheath. Filaments can indicate the filamentary structure of the current in the pinch. Together with the filaments, small compact balls a few mm in diameter were registered by both interferometry and XUV frame pictures. They emerge out of the dense column and their life-time can be greater than hundreds of ns.

Kubes, P.; Paduch, M.; Cikhardt, J.; Kortanek, J.; Cikhardtova, B.; Rezac, K.; Klir, D.; Kravarik, J.; Zielinska, E.

2014-12-01

325

High Amount Cluster Incorporation in Initial Si Film Deposition by SiH4 Plasma Chemical Vapor Deposition  

NASA Astrophysics Data System (ADS)

We have carried out in-situ measurements of Si cluster volume fraction in Si films during plasma chemical vapor deposition by using quartz crystal microbalances (QCM's) together with a cluster-eliminating filter. The cluster volume fraction in films is deduced from film deposition rates with and without Si clusters using QCM's. By employing this method we have revealed a depth profile of the Si cluster volume fraction. A high cluster volume fraction is observed in the initial phase of film deposition. This behavior is compared with time evolution of SiH*, Si* emission intensities and their intensity ratio.

Kim, Yeonwon; Hatozaki, Kosuke; Hashimoto, Yuji; Uchida, Giichiro; Kamataki, Kunihiro; Itagaki, Naho; Seo, Hyunwoong; Koga, Kazunori; Shiratani, Masaharu

2013-01-01

326

Development and initial operating characteristics of the 20 megawatt linear plasma accelerator facility  

NASA Technical Reports Server (NTRS)

A 20-megawatt linear plasma accelerator facility, a steady flow, Faraday-type plasma accelerator facility for high velocity aerodynamic testing, was constructed, developed, and brought to an operational status. The accelerator has a 63.5-mm-square and 0.5-meter-long channel and utilizes nitrogen-seeded with 2 % mole fraction of cesium vapor. Modification of the original accelerator design characteristics and the improvements necessary to make the arc heater a suitable plasma source are described. The measured accelerator electrode current distribution and the electrode-wall potential distributions are given. The computed and the measured values are in good agreement. Measured pitot pressure indicates that an accelerator exit velocity of 9.2 km/sec, is obtained with 30 of the 36 electrode pairs powered and corresponds to a velocity increase to about 2 1/4 times the computed entrance velocity. The computed stagnation enthalpy at the accelerator exit is 92 MJ/kg, and the mass density corresponds to an altitude of about 58 km. The 92 MJ/kg stagnation enthalpy corresponds to a kinetic energy content at low temperature equivalent to a velocity of 13.6 km/sec.

Carter, A. F.; Weaver, W. R.; Mcfarland, D. R.; Wood, G. P.

1971-01-01

327

Effect of quark gluon plasma on charm quark produced in relativistic heavy ion collision  

NASA Astrophysics Data System (ADS)

Charm quarks are produced mainly in the pre-equilibrium stage of heavy ion collision and serve as excellent probes entering the thermalized medium. They come out with altogether different momenta and energies and fragments into D-mesons and decay into non-photonic electrons which are observed experimentally. Here we present the effect of QGP on charm quark production using two different models: first one based on Wang-Huang-Sarcevic model of multiple scattering of partons and the second one is based on Parton Cascade Model with Boltzmann transport equation used for charm quark evolution in QGP.

Younus, Mohammed; Srivastava, Dinesh K.; Bass, Steffen A.

2014-05-01

328

Ionic regulation of the plasma membrane potential of rainbow trout (Salmo gairdneri) spermatozoa: Role in the initiation of sperm motility  

SciTech Connect

The ionic dependence of the trout sperm plasma membrane potential was analysed by measuring the accumulation of the lipophilic ions {sup 3}H-tetraphenylphosphonium (TPP) and {sup 14}C-thiocyanate (SCN) following dilution in artificial media isotonic to the seminal fluid. Our data showed that the trout sperm plasma membrane has a mixed conductance: the plasma membrane potential is sensitive upon the transmembrane gradients of K+, Na+, and H+. This potential is negative (less than -40 mV) in a 125 mM choline chloride media (ChM) at pH 8.5. Replacement of choline by sodium has a small depolarizing effect. The membrane potential is about -15 mV in a 125 mM potassium chloride and falls near zero mV only if valinomycin is added. In ChM changing the external pH (pHe) greatly affects the membrane potential: its value rises from less than -40 mV at pHe 9.0 to -17 mV at pHe 5.0. This pH effect is observed also in presence of sodium or potassium. A decrease in the transmembrane proton gradient produced by increasing internal pH without changing pHe induces also a depolarisation of the plasma membrane. In the different media in which trout sperm remain immotile after dilution (media with (K+) greater than 20-40 mM or a pH less than 7.5) the plasma membrane is more depolarized than in media allowing motility, suggesting a relationship between the state of membrane polarization and the intracellular effectors of the axonemal movement.

Gatti, J.L.; Billard, R.; Christen, R. (Laboratoire de Physiologie de la Reproduction, Nouzilly (France))

1990-06-01

329

Measurement on the lunar surface of impact-produced plasma clouds.  

NASA Technical Reports Server (NTRS)

Simultaneous enhancements of low-energy ions and negative-particle fluxes due to the impact of the Apollo 14 lunar module were observed by the lunar-based charged-particle lunar-environment experiment (CPLEE). The impact occurred 66 km away from CPLEE, and the time delay between impact and flux onset was approximately 1 min. It is argued that the observed charged particles could not have energized at the instant of impact but rather that the impact produced expanding gas clouds and that constituents of these clouds were ionized and accelerated by some continuously active acceleration mechanism. It is further shown that the acceleration mechanism could not have been a static electric field but rather is possibly a consequence of interaction between the solar wind and the gas cloud.

Reasoner, D. L.; O'Brien, B. J.

1972-01-01

330

An ecotoxic risk assessment of residue materials produced by the plasma pyrolysis/vitrification (PP/V) process.  

PubMed

Plasma is the fourth state of matter, following the three states of solid, liquid and gas. Experience has amply demonstrated that solids exposed to the oxygen-deficient plasma flame are converted to liquid, and liquid exposed to the same flame is converted to gas. A low amount of vitrified solid residue material usually remains at the end of this process. Plasma pyrolysis/vitrification (PP/V) has been demonstrated as a safe, efficient, cost-effective technology for the treatment of wastes, including hazardous wastes. Besides the low amounts of gaseous byproducts that PP/V produces, the solid vitrified residue presents a low leachability of pollutants. Studies have been performed in many countries in order to assess the leachability of chemical substances. But from the results of identified studies, none has reported results on the ecotoxicological properties of the leachates. The aim of this study was to contribute to the assessment of ecotoxic risk of four different vitrified materials. Vitrified samples of contaminated soils, municipal solid wastes, and incinerator bottom ashes were submitted to the European leaching pre-standard test number prEN 12457-2. The leachates were analyzed for 22 chemical parameters. The biological characterization comprised the assessment of bioluminescence inhibition of Photobacterium phosphoreum bacterium, growth inhibition of Pseudokirchneriella subcapitata algae and the germination inhibition of Lactuca sativa vegetable. The chemical and ecotoxicological results were analyzed according to the French proposal of Criteria on the Evaluation Methods of Waste Toxicity (CEMWT) and a Toxicity Classification System (TCS). The chemical and ecotoxicological results indicated a low leachability of pollutants and a low toxicity level of leachates. All samples studied were as below the TCS class 1 level (no significant toxicity observed) and as non-ecotoxic for CEMWT. Therefore, the environmental ecotoxic risk of the analyzed vitrified samples was determined to be very low. PMID:11952180

Lapa, N; Santos, Oliveira J F; Camacho, S L; Circeo, L J

2002-01-01

331

Antibody-integrated and functionalized graphite-encapsulated magnetic beads, produced using ammonia gas plasma technology, for capturing Salmonella.  

PubMed

Salmonella spp. is the single and most important causative agent of foodborne infections, especially involving foods such as eggs, milk and meat. To prevent infection, a reliable surveillance system is required that can quickly and sensitively detect Salmonella. Here, we describe the development of antibody-integrated magnetic beads that are functionalized by a novel strategy using ammonia gas plasma. Ammonia plasma, produced by a radio frequency (RF) power supply, was allowed to react with the surface of graphite-encapsulated magnetic beads, resulting in the introduction of amino groups. An anti-Salmonella antibody was then anchored by sulfide groups present on the protein surface to the amino groups of the magnetic beads via N-succinimidyl 3-(2-pyridyldithio) propionate (SPDP). The potential usefulness of these magnetic beads for capturing Salmonella was examined as follows. The beads were incubated with Salmonella in liquid medium and then separated from the supernatant by applying a magnetic field. After thorough washing, adsorption of Salmonella to the beads was confirmed by immunochromatography, polymerase chain reaction and a direct culture assay. Our findings indicate that the capture and concentration of Salmonella using the antibody-integrated magnetic beads was more efficient than commercial Dynabeads® anti-Salmonella, which are conventionally used for concentrating Salmonella from liquid cultures. We believe this novel bead technology will contribute to the enhanced detection of Salmonella. PMID:25660257

Sakudo, Akikazu; Chou, Han; Nagatsu, Masaaki

2015-03-01

332

Formation of metal nanoparticles of various sizes in plasma plumes produced by Ti:sapphire laser pulses  

SciTech Connect

In this paper, an experimental study on generation of nanoparticle various sizes using Ti:sapphire laser pulses, is reported. Nanoparticle formation in plasma plumes of metals like silver and copper, expanding in vacuum, has been studied using stretched pulses of 300 ps duration [subnanoseconds (sub-ns)] from a Ti:sapphire laser. It has been compared with the nanoparticle formation (of the same materials) when compressed pulses of 45 fs duration were used under similar focusing conditions. Nanoparticle formation is observed at intensities as high as 2x10{sup 16} W/cm{sup 2}. The structural analysis of the nanoparticle deposition on a silicon substrate showed that, using 45 fs pulses, smaller nanoparticles of average size {approx}20 nm were generated, whereas on using the sub-ns pulses, larger particles were produced. Also, the visible light transmission and reflection from the nanoparticle film of Ag on glass substrate showed surface plasmon resonance (SPR). The SPR curves of the films of nanoparticles deposited by femtosecond pulses were always broader and reflection/transmission was always smaller when compared with the films formed using the sub-ns pulses, indicating smaller size particle formation by ultrashort pulses. Thus, it has been demonstrated that variation in the laser pulse duration of laser offers a simple tool for varying the size of the nanoparticles generated in plasma plumes.

Chakravarty, U.; Naik, P. A.; Mukherjee, C.; Kumbhare, S. R.; Gupta, P. D. [Raja Ramanna Centre for Advanced Technology, Indore 452 013 (India)

2010-09-15

333

The interaction of polarized microwaves with planar arrays of femtosecond laser-produced plasma filaments in air  

SciTech Connect

The interaction of polarized microwaves with subwavelength arrays of parallel plasma filaments, such as those produced by the propagation of high-power femtosecond laser pulses in ambient air, was investigated by calculating the reflection and transmission coefficients as a function of the incidence angles using the finite-difference time-domain (FDTD) method. The time evolution of these coefficients was calculated and compared with experiments. It is found that the plasma filaments array becomes transparent when the polarization of the microwave radiation is perpendicular to the filaments axis, regardless the incidence angle of the microwave with respect to the filaments, except near grazing incidence. Increasing the filaments electron density or diameter, or decreasing the electron collision frequency or filaments spacing, decreases the transmission and increases the reflection. Transmission decreases when increasing the number of filament layers while reflection remains unchanged as the number of filament layers exceeds a given number ({approx}3 in our case). Transmission slightly increases when disorder is introduced in the filament arrays. The detailed calculation results are compared with those obtained from the simple birefringent slab model, which provides a convenient framework to calculate approximately the properties of filament arrays.

Marian, Anca; El Morsli, Mbark; Vidal, Francois; Payeur, Stephane; Kieffer, Jean-Claude [INRS-Energie, Materiaux et Telecommunications, Universite du Quebec, Varennes, Quebec J3X 1S2 (Canada); Chateauneuf, Marc; Theberge, Francis; Dubois, Jacques [Defense R and D Canada Valcartier, Quebec G3J 1X5 (Canada)

2013-02-15

334

Effects of the dynamics of droplet-based laser-produced plasma on angular extreme ultraviolet emission profile  

SciTech Connect

The emission distribution of extreme ultraviolet (EUV) radiation from droplet targets is dependent on the dynamics of the laser-produced plasma. The EUV emission is measured on a 2% bandwidth centered at 13.5?nm (in-band). The targets of the laser are small (sub-50 ?m) tin droplets, and the in-band emission distribution is measured for different laser irradiances and droplet sizes at various angular positions. Larger droplets lead to a faster decay of EUV emission at larger angles with respect to the laser axis. A decrease in laser irradiance has the opposite effect. The measurements are used together with an analytical model to estimate plume dynamics. Additionally, the model is used to estimate EUV emission distribution for a desired droplet diameter and laser irradiance.

Giovannini, Andrea Z.; Abhari, Reza S. [Laboratory for Energy Conversion, ETH Zurich, 8092 Zurich (Switzerland)

2014-05-12

335

Soft x-ray characterization of a silicon p-n photodiode using a laser produced plasma source (abstract)  

NASA Astrophysics Data System (ADS)

Silicon p-n diodes have proved to be excellent soft x-ray detectors due to their high sensitivity, nominally flat response, and long term stability. Advances in fabrication techniques have overcome many of the limitations of older silicon diodes by minimizing the thickness of the surface dead layer which would otherwise absorb low energy x-ray photons. Silicon photodiodes with extremely thin (80 Å) surface dead layers are now available.1 One of these diodes has been characterized for spectral sensitivity at x-ray photon energies of 163 eV and 1.4 keV using a laser produced plasma soft x-ray source. Measurements have also been made to characterize the impulse response using fourth harmonic laser light from a short pulse (80 ps full width half maximum) NdYAG laser.

Eagleton, R. T.; Ruggles, L. E.

2001-01-01

336

Directed transfer of microwave radiation in sliding-mode plasma waveguides produced by ultraviolet laser in atmospheric air.  

PubMed

Experiments have been performed at hybrid Ti:sapphire/KrF laser facility GARPUN-MTW to develop a novel technique to create a hollow-core sliding-mode plasma-filament waveguide for directed transfer of microwave radiation. Efficient multiphoton air ionization was produced by a train of picosecond 1-TW UV pulses at 248 nm wavelength, or by amplitude-modulated 100 ns pulse combining a short-pulse train with a free-running 1-GW pulse, which detached electrons off O2- ions. Multiple filamentation of UV laser radiation in air was observed, and filamentation theory based on resonance-enhanced ionization was developed to explain the experimental results. PMID:25402935

Zvorykin, Vladimir D; Ionin, Andrei A; Levchenko, Alexei O; Seleznev, Leonid V; Sinitsyn, Dmitrii V; Smetanin, Igor' V; Ustinovskii, Nikolai N; Shutov, Alexei V

2014-11-01

337

Note: Study of extreme ultraviolet and soft x-ray emission of metal targets produced by laser-plasma-interaction  

SciTech Connect

Different metal targets were investigated as possible source material for tailored laser-produced plasma-sources. In the wavelength range from 1 to 20 nm, x-ray spectra were collected with a calibrated spectrometer with a resolution of {lambda}/{Delta}{lambda}= 150 at 1 nm up to {lambda}/{Delta}{lambda}= 1100 at 15 nm. Intense line emission features of highly ionized species as well as continuum-like spectra from unresolved transitions are presented. With this knowledge, the optimal target material can be identified for the envisioned application of the source in x-ray spectrometry on the high energy side of the spectra at about 1 keV. This energy is aimed for because 1 keV-radiation is ideally suited for L-shell x-ray spectroscopy with nm-depth resolution.

Mantouvalou, I.; Bidu, T.; Malzer, W.; Kanngiesser, B. [Institute for Optics and Atomic Physics, Technical University of Berlin, 10623 Berlin (Germany); Jung, R.; Tuemmler, J.; Legall, H.; Stiel, H.; Sandner, W. [Max-Born-Insitute, 12489 Berlin (Germany)

2011-06-15

338

Dynamics and control of the expansion of finite-size plasmas produced in ultraintense laser-matter interactions  

NASA Astrophysics Data System (ADS)

The expansion dynamics of nanometer-sized plasmas is a key issue for applications involving the interaction of ultraintense infrared laser pulses with cluster jets [1], or the irradiation of biological samples with ultraintense x-ray pulses, for biomolecular imaging purposes [2]. Typically, these scenarios involve the prompt formation and expansion of dense plasmas, composed of cold ions and hot electrons. Control over the expansion can be achieved by exploiting the role of the electron dynamics: in particular, using suitable sequences of laser pulses, one can tailor the phase-space dynamics of the ions [3]. This provides the ability to generate large-scale shock shells [4], and opens the way towards intracluster fusion reactions within large D or D-T clusters [3]. Such new possibilities urge the need for a deeper comprehension of the expansion process, in regimes far from that of a pure Coulomb explosion. To this end, a novel Lagrangian model is used, which provides a self-consistent, kinetic description of the collisionless expansion of spherical nanoplasmas: simple relationships are deduced for the key expansion features, valid for a wide range of initial conditions [5], and a threshold in the electron energy is identified, beyond which the energy spectrum becomes monotonic and the Coulomb explosion regime is approached. [1] T. Ditmire et al., Nature 386, 54 (1997); T. Ditmire et al., Nature 398, 489 (1999). [2] R. Neutze et al., Nature 406, 752 (2000); H. Wabnitz et al., Nature 420, 482 (2002). [3] F. Peano et al., Phys. Rev. Lett. 94, 033401 (2005); Phys. Rev. A, 73 , 053202 (2006). [4] A. E. Kaplan et al., Phys. Rev. Lett. 91, 143401 (2003) [5] F. Peano et al., Phys. Rev. Lett. 96, 175002 (2006).

Peano, Fabio

2006-10-01

339

Numerical simulation of microwave amplification in a plasma channel produced in a gas via multiphoton ionisation by a femtosecond laser pulse  

NASA Astrophysics Data System (ADS)

This paper examines the evolution of a nonequilibrium plasma channel produced in xenon by a femtosecond KrF laser pulse. We demonstrate that such a channel can be used to amplify microwave pulses over times of the order of the relaxation time of the photoelectron energy spectrum in xenon. Using the slowly varying amplitude approximation, we analyse the propagation and amplification of an rf pulse in a plasma channel, in particular when the rf field influences the electron energy distribution function in the plasma.

Bogatskaya, A. V.; Volkova, E. A.; Popov, A. M.

2014-12-01

340

LASERS: Self-initiating volume discharge in iodides used for producing atomic iodine in pulsed chemical oxygen --- iodine lasers  

Microsoft Academic Search

A volume self-sustained discharge (VSD) in iodides (C3H7I, C4H9I) and in their mixtures with SF6, N2, and O2 in the presence of small-scale inhomogeneities on the cathode surface is shown to develop in the form of a self-initiating volume discharge (SIVD), i.e., a volume discharge without any preionisation including discharge gaps with a strong edge enhancement of the electric field.

A. A. Belevtsev; S. Yu Kazantsev; A. V. Saifulin; K. N. Firsov

2003-01-01

341

Self-initiating volume discharge in iodides used for producing atomic iodine in pulsed chemical oxygen — iodine lasers  

Microsoft Academic Search

A volume self-sustained discharge (VSD) in iodides (C3H7I, C4H9I) and in their mixtures with SF6, N2, and O2 in the presence of small-scale inhomogeneities on the cathode surface is shown to develop in the form of a self-initiating volume discharge (SIVD), i.e., a volume discharge without any preionisation including discharge gaps with a strong edge enhancement of the electric field.

A A Belevtsev; S Yu Kazantsev; A V Saifulin; K N Firsov

2003-01-01

342

Self-initiating volume discharge in iodides used for producing atomic iodine in pulsed chemical oxygen - iodine lasers  

Microsoft Academic Search

A volume self-sustained discharge (VSD) in iodides (CHI, CHI) and in their mixtures with SF, N, and O in the presence of small-scale inhomogeneities on the cathode surface is shown to develop in the form of a self-initiating volume discharge (SIVD), i.e., a volume discharge without any preionisation including discharge gaps with a strong edge enhancement of the electric field.

A A Belevtsev; S Yu Kazantsev; A V Saifulin; K N Firsov

2003-01-01

343

Chronic vasodilation produces plasma volume expansion and hemodilution in rats: consequences of decreased effective arterial blood volume  

PubMed Central

Plasma volume (PV) expansion is required for optimal pregnancy outcomes; however, the mechanisms responsible for sodium and water retention in pregnancy remain undefined. This study was designed to test the “arterial underfill hypothesis” of pregnancy which proposes that an enlarged vascular compartment (due to systemic vasodilation and shunting of blood to the placenta) results in renal sodium and water retention and PV expansion. We produced chronic vasodilation by 14 days administration of nifedipine (NIF; 10 mg·kg?1·day?1) or sodium nitrite (NaNO2; 70 mg·kg?1·day?1) to normal, nonpregnant female Sprague-Dawley rats. Mean arterial pressure, monitored by telemetry, was reduced by both NIF and NaNO2 but was unchanged in control rats. At day 14, vasodilator treatment lowered hematocrit and increased PV (determined by Evans blue dye dilution). Plasma osmolarity (Posm), sodium (PNa), and total protein concentrations all fell. These responses resemble the responses to normal pregnancy with hemodilution, marked PV expansion, and decreased Posm and PNa. Our previous work indicates a role of increased inner medullary phosphodiesterase-5 (PDE5) in the sodium retention of pregnancy. Here, we found that inner medullary PDE5A mRNA and protein expression were increased by both NIF and NaNO2 treatment vs. control; however, neither renal cortical nor aortic PDE5 expression was changed by vasodilator treatment. We suggest that a primary, persistent vasodilation drives increased inner medullary PDE5 expression which facilitates continual renal Na retention causing “refilling” of the vasculature and volume expansion. PMID:20980409

Fekete, Andrea; Baylis, Chris

2011-01-01

344

Control of translational initiation in the wheat-embryo cell-free protein expression system for producing homogenous products.  

PubMed

Wheat-embryo cell-free protein expression system allows efficient production of a wide variety of proteins. Homogeneity of the end products is an important characteristic of an advanced cell-free system that will be used in a field of protein science such as structural biology. A translation enhancer such as the omega sequence derived from tobacco mosaic virus, that allows cap-independent translation of the mRNA in the cell-free system, is required for low-cost preparation of template mRNAs in the cell-free translation system. However, the use of translational enhancers often leads to unexpected byproducts. Several AUU codons in the omega sequence can potentially function as translation initiators. We confirmed that the in-frame AUU in the omega sequence functions as a non-canonical start codon and results in the extension of the N-terminus of the target protein in some cases. Investigation of the selectivity of non-canonical initiation codon under the control of omega sequence in the wheat-embryo cell-free system revealed that seven non-AUG codons, CUG, AUA, AUU, GUG, ACG, AUC, and UUG, are recognized as translation initiators. We found that the introduction of an in-frame stop codon just upstream of the target open reading frame is an efficient way to avoid unexpected byproducts. This minor but effective modification facilitates production of homogeneous proteins within the wheat-embryo cell-free protein expression system at the preparative scale. PMID:20304073

Ohta, Takashi; Matsuoka, Hiroki; Nomura, Yuhta; Tozawa, Yuzuru

2010-09-01

345

HEAVY ION FUSION SCIENCE VIRTUAL NATIONAL LABORATORY 3nd QUARTER 2009 MILESTONE REPORT: Upgrade plasma source configuration and carry out initial experiments. Characterize improvements in focal spot beam intensity  

SciTech Connect

Simulations suggest that the plasma density must exceed the beam density throughout the drift compression and focusing section in order to inhibit the space charge forces that would limit the spot size and beam intensity on the target. WDM experiments will therefore require plasma densities up to 10{sup 14}/cm{sup 3}, with the highest density in the last few centimeters before the target. This work was guided by the simulations performed for the FY09 Q1 milestone. This milestone has been met and we report results of modifications made to the NDCX beamline to improve the longitudinal and radial distribution of the neutralizing plasma in the region near the target plane. In Section 2, we review pertinent simulation results from the FY09 Q1 milestone. Section 3 describes the design, and beam measurements following installation, of a biased, self-supporting metal grid that produces neutralizing electrons from glancing interception of beam ions. Section 4 describes the design and initial testing of a compact Ferro-Electric Plasma Source (FEPS) that will remove the remaining 'exclusion zone' in the neutralizing plasma close to the target plane. Section 5 describes the modification of the beamline to decrease the gap between the FEPS section exit and the final focus solenoid (FFS). Section 6 presents a summary and conclusions.

Lidia, S.; Anders, A.; Barnard, J.J.; Bieniosek, F.M.; Dorf, M.; Faltens, A.; Friedman, A.; Gilson, E.; Greenway, W.; Grote, D.; Jung, J.Y.; Katayanagi, T.; Logan, B.G.; Lee, C.W.; Leitner, M.; Ni, P.; Pekedis, A.; Regis, M. J.; Roy, P. K.; Seidl, P. A.; Waldron, W.

2009-06-30

346

Similar proportions of immunoglobulin A1 (IgA1) protease-producing streptococci in initial dental plaque of selectively IgA-deficient and normal individuals.  

PubMed Central

By comparing the initial colonization of cleaned teeth in immunoglobulin A (IgA)-deficient, IgM-compensating individuals with that in normal individuals, no significant difference in the proportion of IgA1 protease-producing streptococci was found. Thus, as one of several bacterial means of immune evasion, the ability to cleave secretory IgA1 does not appear essential to the successful adherence of oral streptococci. PMID:8359924

Reinholdt, J; Friman, V; Kilian, M

1993-01-01

347

Patient-centered medical home initiative produced modest economic results for Veterans Health Administration, 2010-12.  

PubMed

In 2010 the Veterans Health Administration (VHA) began a nationwide initiative called Patient Aligned Care Teams (PACT) that reorganized care at all VHA primary care clinics in accordance with the patient-centered medical home model. We analyzed data for fiscal years 2003-12 to assess how trends in health care use and costs changed after the implementation of PACT. We found that PACT was associated with modest increases in primary care visits and with modest decreases in both hospitalizations for ambulatory care-sensitive conditions and outpatient visits with mental health specialists. We estimated that these changes avoided $596 million in costs, compared to the investment in PACT of $774 million, for a potential net loss of $178 million in the study period. Although PACT has not generated a positive return, it is still maturing, and trends in costs and use are favorable. Adopting patient-centered care does not appear to have been a major financial risk for the VHA. PMID:24889947

Hebert, Paul L; Liu, Chuan-Fen; Wong, Edwin S; Hernandez, Susan E; Batten, Adam; Lo, Sophie; Lemon, Jaclyn M; Conrad, Douglas A; Grembowski, David; Nelson, Karin; Fihn, Stephan D

2014-06-01

348

Application of an enzyme-labeled antigen method for visualizing plasma cells producing antibodies against Strep A, a carbohydrate antigen of Streptococcus pyogenes, in recurrent tonsillitis.  

PubMed

Streptococcus pyogenes is the main causative pathogen of recurrent tonsillitis. Histologically, lesions of recurrent tonsillitis contain numerous plasma cells. Strep A is an antigenic carbohydrate molecule on the cell wall of S. pyogenes. As expected, plasma cells in subjects with recurrent tonsillitis secrete antibodies against Strep A. The enzyme-labeled antigen method is a novel histochemical technique that visualizes specific antibody-producing cells in tissue sections by employing a biotin-labeled antigen as a probe. The purpose of the present study was to visualize plasma cells producing antibodies reactive with Strep A in recurrent tonsillitis. Firstly, the lymph nodes of rats immunized with boiled S. pyogenes were paraformaldehyde-fixed and specific plasma cells localized in frozen sections with biotinylated Strep A. Secondly, an enzyme-labeled antigen method was used on human tonsil surgically removed from 12 patients with recurrent tonsillitis. S. pyogenes genomes were PCR-detected in all 12 specimens. The emm genotypes belonged to emm12 in nine specimens and emm1 in three. Plasma cells producing anti-Strep A antibodies were demonstrated in prefixed frozen sections of rat lymph nodes, 8/12 human specimens from patients with recurrent tonsillitis but not in two control tonsils. In human tonsils, Strep A-reactive plasma cells were observed within the reticular squamous mucosa and just below the mucosa, and the specific antibodies belonged to either IgA or IgG classes. Our technique is effective in visualizing immunocytes producing specific antibodies against the bacterial carbohydrate antigen, and is thus a novel histochemical tool for analyzing immune reactions in infectious disorders. PMID:25403787

Onouchi, Takanori; Mizutani, Yasuyoshi; Shiogama, Kazuya; Inada, Ken-Ichi; Okada, Tatsuyoshi; Naito, Kensei; Tsutsumi, Yutaka

2015-01-01

349

Al2O3 Growth on (100) In0:53Ga0:47As Initiated by Cyclic Trimethylaluminum and Hydrogen Plasma Exposures  

E-print Network

Al2O3 Growth on (100) In0:53Ga0:47As Initiated by Cyclic Trimethylaluminum and Hydrogen Plasma) GdGaOx dielectrics,10) and in situ Al2O3 growth.11) MOS capacitors (MOSCAPs) on In0:53Ga0:47As using report measurements on In0:53Ga0:47As/Al2O3 MOSCAPs for alternative dielectric growth initiation

Rodwell, Mark J. W.

350

Comparative study of atmospheric pressure low and radio frequency microjet plasmas produced in a single electrode configuration  

SciTech Connect

Microsize jet-type plasmas were generated in a single pin electrode structure source for two separate input frequencies of 50 kHz and 13.56 MHz in the ambient air. The copper pin electrode radius was 360 {mu}m, and it was placed in a Pyrex tube with a radius of 3 mm for helium gas supply. Due to the input frequency difference, the generated plasmas showed distinct discharge characteristics for their plasma physical appearances, electrical properties, gas temperatures, and optical properties. Strengths and weaknesses of both plasmas were discussed for further applications.

Kim, Dan Bee; Rhee, J. K.; Gweon, B.; Moon, S. Y.; Choe, W. [Department of Physics, Korea Advanced Institute of Science and Technology, 335 Gwahangno, Yuseong-gu, Daejeon 305-701 (Korea, Republic of)

2007-10-08

351

The use of neutral beam heating to produce high performance fusion plasmas, including the injection of tritium beams into the Joint European Torus (JET)  

SciTech Connect

The neutral beam injection (NBI) system of the Joint European Torus (JET) [[ital Plasma] [ital Physics] [ital and] [ital Controlled] [ital Nuclear] [ital Fusion] [ital Research] (International Atomic Energy Agency, Vienna, 1985), Vol. 1, p. 11] has proved to be an extremely effective and flexible heating method capable of producing high performance plasmas and performing a wide range of related physics experiments. High fusion performance deuterium plasmas have been obtained in the hot-ion (HI) H-mode regime, using the central particle fueling and ion heating capabilities of the NBI system in low target density plasmas, and in the pellet enhanced plasma (PEP) H-mode regime, where the good central confinement properties of pellet fueled plasmas are exploited by additional heating and fueling as well as the transition to H mode. The HI H-mode configuration was used for the First Tritium Experiment (FTE) in JET in which NBI was used to heat the plasma using 14 D[sup 0] beams and, for the first time, to inject T[sup 0] using the two remaining beams. These plasmas had a peak fusion power of 1.7 MW from deuterium--tritium (D--T) fusion reactions. The capability for injection of a variety of beam species (H[sup 0], D[sup 0], [sup 3]He[sup 0], and [sup 4]He[sup 0]) has allowed the study of confinement variation with atomic mass and the simulation of [alpha]-particle transport. Additionally, the use of the NBI system has permitted an investigation of the plasma behavior near the toroidal [beta] limit over a wide range of toroidal field strengths.

Thompson, E.; Stork, D.; de Esch, H.P.L. (JET Joint Undertaking, Abingdon, Oxon 0X14 3EA (United Kingdom)); the JET Team

1993-07-01

352

Studies of the initial phases of exploding W and Al wire and wire-array plasma formation using x-ray backlighting  

SciTech Connect

Exploding W and Al wires and wire arrays have been investigated using direct (point-projection) x-ray backlighting as the principal diagnostic method. A 4.5 kA amplitude, 350 ns quarter-period rise time sinusoidal current source which damps in about 5 {micro}s is delivered to one or more fine W (7.5, 10 or 13.5 {micro}m) or Al (13.5 or 25 {micro}m) wires approximately 6 cm away from one or two Mo X-pinch x-ray backlighter sources. The X-pinches are placed in parallel between the output electrodes of the 450 kA, 100 ns XP pulser at Cornell University, each thereby producing a sub-nanosecond x-ray pulse. The source size is small enough to permit micron-scale spatial resolution images of the exploding wires on x-ray film. By varying the relative timing between pulsing the current source for the W or Al wire or wires and the XP pulser, images of the initial explosion phase of W and Al wires have been obtained at times ranging upwards from about 100 ns after the start of the 4.5 kA current source. Al wires expand substantially with the linear current rise for 100 ns to 1 kA in a single wire. By the time (350 ns) of peak current in a single Al wire, the Al has expanded sufficiently to be undetectable using the 3--4.8 keV x-ray backlighter source. However, two Al wires with 2 kA per wire expand more slowly and are still visible up to at least 450 ns. By contrast, W wires do not expand significantly during the first {approximately} 1 {micro}s. A laser schlieren imaging system to image the coronal plasma around the wire cores has been synchronized with the x-ray backlighter sources in order to see the tenuous outer coronal plasma which is invisible in the x-rays images. Comparisons of schlieren and x-ray backlighting images will be presented. The implications of these results to cylindrical plasma formation in exploding wire arrays by the prepulse on the Z accelerator, and to 2 and 3 D MHD code validation will be discussed.

Sinars, D.B.; Greenly, J.B.; Pikuz, S.A.; Shelkovenko, T.A.; Hammer, D.A.; Kusse, B.R.

1999-07-01

353

Thermophilic-anaerobic digestion to produce class A biosolids: initial full-scale studies at Hyperion Treatment Plant.  

PubMed

The highest quality of biosolids is called exceptional quality. To qualify for this classification, biosolids must comply with three criteria: (1) metal concentrations, (2) vector-attraction reduction, and (3) the Class A pathogen-density requirements. The City of Los Angeles Bureau of Sanitation Hyperion Treatment Plant (HTP) (Playa del Rey, California) meets the first two requirements. Thus, the objective of this study was to ensure that HTP's biosolids production would meet the Class A pathogen-reduction requirements following the time-temperature regimen for batch processing (U.S. EPA, 1993; Subsection 32, Alternative 1). Because regulations require the pathogen limits to be met at the last point of plant control, biosolids sampling was not limited to immediately after the digesters, i.e., the digester outflows. The sampling extended to several locations in HTP's postdigestion train, in particular, the last points of plant control, i.e., the truck loading facility and the farm for land application. A two-stage, thermophilic-continuous-batch process, consisting of a battery of six egg-shaped digesters, was established in late 2001 for phase I of this study and modified in early 2002 for phase II. As the biosolids were discharged from the second-stage digesters, the Salmonella sp. (pathogen) and fecal-coliform (indicator) densities were well below the limits for Class A biosolids, even though the second-stage-digester temperatures were a few degrees below the temperature required by Alternative 1. Salmonella sp. densities remained below the Class A limit at all postdigestion sampling locations. Fecal-coliform densities were also below the Class A limit at postdigestion-sampling locations, except the truck-loading facility (phases I and II) and the farm for final use of the biosolids (phase II). Although federal regulations require one of the limits for either fecal coliforms or Salmonella sp. to be met, local regulations in Kern County, California, where the biosolids are land-applied, require compliance with both bacterial limits. Additional work identified dewatering, cooling of biosolids after the dewatering centrifuges, and contamination as possible factors in the rise in density of fecal coliforms. These results provided the basis for the full conversion of HTP to the Los Angeles continuous-batch, thermophilic-anaerobic-digestion process. During later phases of testing, this process was demonstrated to produce fully disinfected biosolids at the farm for land application. PMID:16566524

Iranpour, R; Cox, H H J; Oh, S; Fan, S; Kearney, R J; Abkian, V; Haug, R T

2006-02-01

354

Laser-produced plasma sensor-probe system for in situ molten metal analysis. Final technical report  

SciTech Connect

The radically new methodology of in-situ laser-produced plasma (LPP) analysis of molten metals, as developed at Lehigh University, has been implemented into an LPP sensor-probe system, ready for deployment at steelmaking facilities. The system consists of an LPP sensor-probe head, which is immersed into the molten metal bath for the short duration of measurement, a control console, an umbilical cord connecting the above two units, and a support console providing coolants and pneumatic supports to the control console. The Department of Energy funding has supported Phase III-A and -B of the project in a joint sponsorship with AISI, CTU 5-2 Consortium, and Lehigh University. The objectives have been to: (1) implement the molten metal calibration protocol for the LPP analysis methodology; (2) implement the methodology in the form of a second-generation LPP sensor-probe system, which facilitates real-time process control by in-situ determination of elemental composition of molten steel alloys; (3) deploy such developmental systems in steelmaking facilities; (4) upgrade the systems to a third-generation design; and (5) effect technology transfer by selecting a manufacturer of commercial LPP sensor-probe systems. Four of the five objectives have been fully met. The deployment objective has been partially realized at present. The full LPP sensor-probe system has been put through trial immersion runs at a foundry, but its deployment at steelmaking facilities has progressed to a stage where various issues of financial and legal nature are being codified into a formal agreement between a host site and Lehigh University.

Kim, Y.W.

1997-01-28

355

Analysis of laser-produced aerosols by inductively coupled plasma mass spectrometry: transport phenomena and elemental fractionation.  

PubMed

The transport phenomena of laser-produced aerosols prior to analysis by inductively coupled plasma mass spectrometry (ICPMS) were examined. Aerosol particles were visualized over the cross section of a transport tube attached to the outlet of a conventional ablation cell by light scattering using a pulsed laser source. Experiments were carried out under laminar or turbulent in-cell flow conditions applying throughputs of up to 2.0 L/min and reveal the nature of aerosol transportation to strongly depend on both flow rate and carrier gas chosen. For instance, laser ablation (LA) using laminar in-cell flow and helium as aerosol carrier resulted in stationary but inhomogeneous dispersion patterns. In addition, aerosols appear to be separated into two coexisting phases consisting of (i) dispersed particles that accumulate at the boundary layer of several vortex channel flows randomly arranged along the tube axis and (ii) larger fragments moving inside. The occurrence of these fragments was found to affect the accuracy of Si-, Zn-, and Cd-specific ICPMS analyses of aerosols released by LA of silicate glass (SRM NIST610). Accuracy drifts of more than 10% were observed for helium flow rates of >1 L/min, most probably, due to preferential evaporation and diffusion losses of volatile constituents inside the ICP. The utilization of turbulent in-cell flow made the vortex channels collapse and resulted in an almost complete aerosol homogenization. In contrast, LA using argon as aerosol carrier generally yielded a higher degree of dispersion, which was nearly independent of the flow conditions applied. To illustrate the differences among laminar and turbulent in-cell flow, furthermore, the velocity field inside the ablation cell was simulated by computational fluid dynamics. PMID:18205331

Koch, J; Wälle, M; Dietiker, R; Günther, D

2008-02-15

356

Multivariate Protein Signatures of Pre-Clinical Alzheimer's Disease in the Alzheimer's Disease Neuroimaging Initiative (ADNI) Plasma Proteome Dataset  

E-print Network

Medicine [9], proposed that the abundance of 18 proteins in plasmaPlasma samples were assayed for 190 analytes using the ‘Human DiscoveryMAP’, developed on the Luminex xMAP platform by Rules-Based Medicine.

Johnstone, Daniel; Milward, Elizabeth A.; Berretta, Regina; Moscato, Pablo

2012-01-01

357

Low- and high-order harmonic generation in the extended plasmas produced by laser ablation of zinc and manganese targets  

NASA Astrophysics Data System (ADS)

The systematic studies of the harmonic generation of ultrashort laser pulses in the 5-mm-long Zn and Mn plasmas (i.e., application of nanosecond, picosecond, and femtosecond pulses for ablation, comparison of harmonic generation from atomic, ionic, and cluster-contained species of plasma, variation of plasma length, two-color pump of plasmas, etc.) are presented. The conversion efficiency of the 11th-19th harmonics generated in the Zn plasma was ˜5 × 10-5. The role of the ionic resonances of Zn near the 9th and 10th harmonics on the enhancement of harmonics is discussed. The enhancement of harmonics was also analyzed using the two-color pump of extended plasmas, which showed similar intensities of the odd and even harmonics along the whole range of generation. The harmonics up to the 107th order were demonstrated in the case of manganese plasma. The comparison of harmonic generation in the 5-mm-long and commonly used short (?0.5 mm) plasma plumes showed the advanced properties of extended media.

Ganeev, R. A.; Baba, M.; Suzuki, M.; Yoneya, S.; Kuroda, H.

2014-12-01

358

Use of free radicals on the surface of plasma polymer for the initiation of a polymerization reaction.  

PubMed

A novel approach to functionalize plasma polymer films (PPFs) through the grafting polymerization initiated from free radicals trapped in the film was developed in this work. 2-Ethylhexyl acrylate (EHA) was chosen as radically polymerizable monomer given the wide use of its corresponding polymer in coating and adhesive applications. The occurrence of the grafting was first confirmed by time-of-flight secondary ion mass spectrometry (ToF-SIMS) and X-ray photoelectron spectroscopy (XPS). Then grafted chains were studied in more detail. The thickness of grafted chains was quantitatively estimated by angle-resolved XPS (ARXPS), while their morphology and interfacial behavior were qualitatively investigated by atomic force microscopy (AFM), contact angle measurements, and quartz crystal microbalance (QCM). The latter technique provided additional insights regarding the swelling behavior of the grafted layer and its stability upon exposure to challenging environments. Reported scientific findings suggest to use this approach for the covalent binding of a very thin layer on the top surface of a PPF without affecting its bulk properties. PMID:24143897

Khelifa, Farid; Ershov, Sergey; Habibi, Youssef; Snyders, Rony; Dubois, Philippe

2013-11-27

359

Characteristic of the high-density core plasma produced by non-spherical implosion for fast ignition  

NASA Astrophysics Data System (ADS)

For the fast ignition scheme, formation of a high-density core plasma is one of the critical issues. Using 2-D integrated implosion code PINOCO, we have simulated the cone-guided implosion and observed the existence of high-density core plasma. The characteristic of the core plasma affects the burning efficiency of DT fuel heated by the ultra-intense laser. Therefore, we have investigated the detail properties of core plasma which is imploded by non-spherical implosion. Those simulations are same scale size as the FIREX-I experiment at ILE Osaka Univ. Especially, a jet formation and hydrodynamic around the tip of the cone is important. We will show the simulated result of implosion of cone-guided target, and discuss the optimized laser pulse and target parameters for fast ignition. This work was supported by MEXT, Grant-in Aid for Creative Scientific Research(15GS0214).

Nagatomo, Hideo; Johzaki, Tomoyuki; Sunahara, Atsushi; Takeda, Daisuke; Mima, Kunioki

2004-11-01

360

Figure 1: Artificially colored image of the plasma produced with a cylindrical lens. The laser travels in the Z-  

E-print Network

. Whittum13, R. Williams3, J. Wurtele6. Abstract The proposal to perform a series of plasma lens experiments of Tennessee, Knoxville, Tennessee 15Utsunomiya University, Utsunomiya, Japan length of 1.3 ps, and is similar

McDonald, Kirk

361

Crystal structure and oxidation behavior of Aluminum-containing stainless steel coatings produced by cryomilling and spark plasma sintering  

NASA Astrophysics Data System (ADS)

Three austenitic 316LSS alloys containing 0, 2 and 6wt% Al were prepared by cryomilling and Spark Plasma Sintering (SPS). It was shown that aluminum influences the FCC to BCC strain induced phase transformation that occurs during milling and also the FCC recovery during heat treatment and SPS consolidation. The Al-containing SS had accelerated strain induced transformation in the early stage of milling, while the rate of transformation became similar thereafter for all systems. The degree to which the induced BCC structure reverted to FCC was found dependent upon the Al content. Complete recovery of the FCC during heat treatment was achieved between 565 to 594°C for nSS6Al and 605 to 618°C for nSS2Al, depending on the heating rate. However, heat treatment of nSS0Al up to 1000°C resulted in incomplete reversion of the strain induced structure. The SPS process was found to minimally influence the FCC recovery compared to conventional powder consolidation heat treatments. The energy supplied by the SPS process was insufficient to overcome the activation energy governing the rearrangement of dislocations required to complete the FCC recovery. The modification of the composition of 316LSS combined with a grain refinement to the nanometer level was investigated to determine the potential gain in oxidation resistance on coatings produced using the SPS technique. For the base alloy, the increased number of diffusion paths present in nanostructured materials yielded a thicker oxide scale, when compared to conventional SS, and this independently on the tested oxidation temperature (500°C, 800°C and 1000°C). For the nanostructured SS, the scale had an enriched Cr-content which improves the resistance to static and cyclic oxidation, and adherence to the substrate. Aluminum was also added at concentrations of 2 and 6 wt% to the base SS, which caused the scale composition to change to a continuous double layer consisting of an inner Al2O3 and an outer Cr2O3 for both alloys when oxidized at 1000°C and for the 6 wt% Al sample when oxidized at 800°C. The activation energy for oxidation of the nanostructured coatings was approximately half of the one for the conventional SS. The oxidation rate constant for the Al-containing SS alloys studied was found to be lower than for the Al-free grades, which is associated with the Al2O3 layer providing a diffusion barrier. However, the conventional SS had a lower oxidation rate constant than the nanostructured alloy because of the lower volume fraction of grain boundaries providing a slower diffusion of the same elements composing the scale.

Abdulaziz, Al-Mathami

362

In situ visualization of plasma cells producing antibodies reactive to Porphyromonas gingivalis in periodontitis: the application of the enzyme-labeled antigen method  

PubMed Central

Porphyromonas gingivalis is a keystone periodontal pathogen. Histologocally, the gingival tissue in periodontitis shows dense infiltration of plasma cells. However, antigens recognized by antibodies secreted from the immunocytes remain unknown. The enzyme-labeled antigen method was applied to detecting plasma cells producing P. gingivalis-specific antibodies in biopsied gingival tissue of periodontitis. N-terminally biotinylated P. gingivalis antigens, Ag53 and four gingipain domains (Arg-pro, Arg-hgp, Lys-pro and Lys-hgp) were prepared by the cell-free protein synthesis system using wheatgerm extract. With these five labeled proteins as probes, 20 lesions of periodontitis were evaluated. With the AlphaScreen method, antibodies against any one of the five P. gingivalis antigens were detected in 11 (55%) serum samples and 17 (85%) tissue extracts. Using the enzyme-labeled antigen method on paraformaldehyde-fixed frozen sections of gingival tissue, plasma cells were labeled with any one of the five antigens in 17 (94%) of 18 specimens, in which evaluable plasma cells were detected. The positivity rates in periodontitis were significantly higher than those found previously in radicular cysts (20% in sera and 33% in tissue extracts with the AlphaScreen method, and 25% with the enzyme-labeled antigen method). Our findings directly indicate that antibodies reactive to P. gingivalis are locally produced in the gingival lesions, and that inflammatory reactions against P. gingivalis are involved in periodontitis. PMID:24698402

Mizutani, Y; Tsuge, S; Takeda, H; Hasegawa, Y; Shiogama, K; Onouchi, T; Inada, K; Sawasaki, T; Tsutsumi, Y

2014-01-01

363

Stable HIV-1 integrase diversity during initial HIV-1 RNA Decay suggests complete blockade of plasma HIV-1 replication by effective raltegravir-containing salvage therapy  

PubMed Central

Background There is legitimate concern that minority drug-resistant mutants may be selected during the initial HIV-1 RNA decay phase following antiretroviral therapy initiation, thus undermining efficacy of treatment. The goal of this study was to characterize viral resistance emergence and address viral population evolution during the first phase of viral decay after treatment containing initiation. Findings 454 sequencing was used to characterize viral genetic diversity and polymorphism composition of the HIV-1 integrase gene during the first two weeks following initiation of raltegravir-containing HAART in four ART-experienced subjects. No low-prevalence Raltegravir (RAL) drug resistance mutations (DRM) were found at baseline. All patients undergoing treatment received a fully active ART according to GSS values (GSS???3.5). No emergence of DRM after treatment initiation was detected. Longitudinal analysis showed no evidence of any other polymorphic mutation emergence or variation in viral diversity indexes. Conclusions This suggests that fully active salvage antiretroviral therapy including raltegravir achieves a complete blockade of HIV-1 replication in plasma. It is unlikely that raltegravir-resistant HIV-1 may be selected in plasma during the early HIV-1 RNA decay after treatment initiation if the administered therapy is active enough. PMID:24304606

2013-01-01

364

Study of plasma start-up initiated by second harmonic electron cyclotron resonance heating on WEGA experiment  

SciTech Connect

Although both 1st harmonic ordinary mode (O1) and 2nd harmonic extra-ordinary mode (X2) have been successfully used to initiate pre-ionization and breakdown in many devices, a complete theoretical model is still missing to explain the success of this method. Moreover, some experimental observations are not completely understood, such as what occurs during the delay time between the turn-on of ECRH power and first signals of density or light measurements. Since during this free period the ECRH power has to be absorbed by in-vessel components, it is of prime importance to know what governs this delay time. Recently, dedicated start-up experiments have been performed on WEGA, using a 28 GHz ECRH system in X2-mode. This machine has the interesting capability to be run also as a tokamak allowing comparative experiments between stellarator (?/2? > 0) and tokamak (?/2? = 0) configurations. Different scans in heating power, neutral gas pressure, and rotational transform (?) show clearly that the start-up is a two step process. A first step following the turn-on of the ECRH power during which no measurable electron density (or just above the noise level in some cases), ECE and radiated power is detected. Its duration depends strongly on the level of injected power. The second step corresponds to the gas ionization and plasma expansion phase, with a velocity of density build-up and filling-up of the vessel volume depending mainly on pressure, gas and rotational transform. Moreover, an interesting scenario of ECRH pre-ionization without loop voltage in tokamak configuration by applying a small optimal vertical field is relevant for start-up assistance on future experiments like ITER. The results from this experimental parametric study are useful for the modeling of the start-up assisted by the second harmonic electron cyclotron resonance heating. The aim of this work is to establish predictive scenarios for both ITER and W7-X operation.

Preynas, M.; Laqua, H. P.; Otte, M.; Stange, T.; Aßmus, D. [Max Planck Institut für Plasmaphysik, EURATOM Association, D-17491 Greifswald (Germany); Wauters, T. [Association Euratom-Belgian State, LPP-ERM/KMS, 1000 Brussels (Belgium)

2014-02-12

365

Study of plasma start-up initiated by second harmonic electron cyclotron resonance heating on WEGA experiment  

NASA Astrophysics Data System (ADS)

Although both 1st harmonic ordinary mode (O1) and 2nd harmonic extra-ordinary mode (X2) have been successfully used to initiate pre-ionization and breakdown in many devices, a complete theoretical model is still missing to explain the success of this method. Moreover, some experimental observations are not completely understood, such as what occurs during the delay time between the turn-on of ECRH power and first signals of density or light measurements. Since during this free period the ECRH power has to be absorbed by in-vessel components, it is of prime importance to know what governs this delay time. Recently, dedicated start-up experiments have been performed on WEGA, using a 28 GHz ECRH system in X2-mode. This machine has the interesting capability to be run also as a tokamak allowing comparative experiments between stellarator (?/2? > 0) and tokamak (?/2? = 0) configurations. Different scans in heating power, neutral gas pressure, and rotational transform (?) show clearly that the start-up is a two step process. A first step following the turn-on of the ECRH power during which no measurable electron density (or just above the noise level in some cases), ECE and radiated power is detected. Its duration depends strongly on the level of injected power. The second step corresponds to the gas ionization and plasma expansion phase, with a velocity of density build-up and filling-up of the vessel volume depending mainly on pressure, gas and rotational transform. Moreover, an interesting scenario of ECRH pre-ionization without loop voltage in tokamak configuration by applying a small optimal vertical field is relevant for start-up assistance on future experiments like ITER. The results from this experimental parametric study are useful for the modeling of the start-up assisted by the second harmonic electron cyclotron resonance heating. The aim of this work is to establish predictive scenarios for both ITER and W7-X operation.

Preynas, M.; Laqua, H. P.; Otte, M.; Stange, T.; Wauters, T.; Aßmus, D.

2014-02-01

366

Influence of Non-MHD Flutes on the Efficiency of Energy Transfer from the Laser-Produced, ICF and Space Exploding Plasmas to Magnetic Field  

SciTech Connect

The results of <> experiment with quasispherical Laser-produced Plasma Clouds (LPC) expanding into strong (B{sub 0} {approx}10 kG) and uniform magnetic field at KI-1 facility of ILP are presented. Main characteristics and the influence of non-MHD flute instability onto effectiveness of plasma-field interaction were studied especially for the purpose of plasma confinement and the direct conversion of its kinetic energy into magnetic and electric ones (of pick-up coils). A new model of enhanced field penetration into plasma due to Hall-effect in its flutes and under conditions of finite ion Larmor radius is discussed. The data obtained on the current generation by LPC in short-circuited surrounding coils (with total conversion efficiency up to {approx}10%) are compared with the models of ILP and last results of relevant 3D/PIC calculations done at KU. All these results show the opportunities of LPC-experiments to simulate both space exploding plasmas (AMPTE) and MHD-effects of ICF micro-explosions in planned NIF experiments for study Laser Fusion Rocket like a VISTA.

Zakharov, Yuri P.; Antonov, Vladimir M.; Boyarintsev, Eduard L.; Melekhov, Alexandr V.; Posukh, Vitaliy G.; Shaikhislamov, Ildar F.; Nakashima, Hideki; Vchivkov, Konstantin V

2005-01-15

367

Subpicosecond 41.8-nm X-ray laser in the plasma produced by femtosecond laser irradiation of a xenon cluster jet  

SciTech Connect

Model calculations are performed of the radiation gain for the 4d5d (J = 0) - 4d5p (J = 1) transition with a wavelength of 41.8 nm in Pd-like xenon ions in the plasma produced by femtosecond laser irradiation of a xenon cluster jet. Conditions for the excitation of an ultrashort-pulse ({approx}1 ps) X-ray laser are discussed. (lasers)

Ivanova, E P [Institute of Spectroscopy, Russian Academy of Sciences, Troitsk, Moscow region (Russian Federation)

2012-12-31

368

Plasma transferred arc surface alloying of a construction steel to produce a metal matrix composite tool steel with TiC as reinforcing particles  

Microsoft Academic Search

A wear resistant metal matrix composite with a hard tool steel matrix and titanium carbides (TiCs) as reinforcing particles was produced on the surface of a plain carbon steel, using the technique of plasma transferred arc alloying. An almost uniform alloyed layer free of cracks and porosities having a thickness of 0.8–1.0 mm and a hardness of 850–900 HV was

L Bourithis; Ath Milonas; G. D Papadimitriou

2003-01-01

369

Bio-modulators in platelet-rich plasma: a comparison of the amounts in products from healthy donors and patients produced with three different techniques  

PubMed Central

Background Platelet-rich plasma consists of platelets concentrated in a small volume of plasma and constitutes a reservoir of bio-modulators potentially useful in tissue repair. The amounts of bio-modulators detectable in platelet-rich plasma prepared with various commercial or “in house” methods have been reported, but virtually all the analyses described have been performed on platelet-rich plasma derived from healthy donors. Since leucocyte contamination is technically unavoidable, we investigated whether platelet-rich plasma prepared from patients could contain different amounts of bio-modulators because of a possible activated status of the leucocytes. Materials and methods We evaluated platelet-rich plasma prepared with three different techniques (the commercial Vivostat and Biomet recover GPS II systems and an “in house” method) starting from whole blood from healthy donors and patients. Specifically, we compared the levels of sHLA-I, sFasL, platelet-derived growth factor, transforming growth factors-beta and vascular endothelial growth factor in the platelet-rich plasma releasates according to the method of preparation and to the immune system activation status of the subjects. Results With the exception of sHLA-I levels, no differences were found in the surrogate indices of lymphocyte activation between healthy donors and patients. No significant differences were found in sHLA-I, sFasL, platelet-derived growth factor, transforming growth factors-beta and vascular endothelial growth factor levels detectable in platelet-rich plasma produced with the three different methods in either healthy donors or patients. Discussion On the whole our findings indicate that the overall content of bio-modulators in autologous platelet-rich plasma is not influenced by T-lymphocyte activation status, at least in patients with uncomplicated femoral fractures. The amounts of sFasL and sHLA-I detected in all the platelet-rich plasma releasates studied were very small, far below the amounts detectable in all clinically available blood derivatives and absolutely insufficient to induce sHLA-I and/or sFasL mediated immunomodulation. PMID:23399357

Ubezio, Gianluca; Ghio, Massimo; Contini, Paola; Bertorello, Roberta; Marino, Gennaro; Tomasini, Andrea; Tripodi, Gino

2014-01-01

370

Guiding of high intensity ultrashort laser pulses in plasma channels produced with the dual laser pulse ignitor-heater technique  

SciTech Connect

The authors present results of experimental investigations of laser guiding in plasma channels. A new technique for plasma channel creation, the Ignitor-Heater scheme is proposed and experimentally tested in hydrogen and nitrogen. It makes use of two laser pulses. The Ignitor, an ultrashort (< 100 fs) laser pulse, is brought to a line focus using a cylindrical lens to ionize the gas. The Heater pulse (160 ps long) is used subsequently to heat the existing spark via inverse Bremsstrahlung. The hydrodynamic shock expansion creates a partially evacuated plasma channel with a density minimum on axis. Such a channel has properties of an optical waveguide. This technique allows creation of plasma channels in low atomic number gases, such as hydrogen, which is of importance for guiding of highly intense laser pulses. The channel density was diagnosed with time resolved longitudinal interferometry. From these measurements the plasma temperature was inferred. The guiding properties of the channels were tested by injecting a > 5 {times} 10{sup 17} W/cm{sup 2}, 75 fs laser pulse.

Volfbeyn, P.; Leemans, W.P.

1998-07-01

371

Production of large volume, strongly magnetized laser-produced plasmas by use of pulsed external magnetic fields.  

PubMed

The production of strongly magnetized laser plasmas, of interest for laboratory astrophysics and inertial confinement fusion studies, is presented. This is achieved by coupling a 16 kV pulse-power system. This is achieved by coupling a 16 kV pulse-power system, which generates a magnetic field by means of a split coil, with the ELFIE laser facility at Ecole Polytechnique. In order to influence the plasma dynamics in a significant manner, the system can generate, repetitively and without debris, high amplitude magnetic fields (40 T) in a manner compatible with a high-energy laser environment. A description of the system and preliminary results demonstrating the possibility to magnetically collimate plasma jets are given. PMID:23635194

Albertazzi, B; Béard, J; Ciardi, A; Vinci, T; Albrecht, J; Billette, J; Burris-Mog, T; Chen, S N; Da Silva, D; Dittrich, S; Herrmannsdörfer, T; Hirardin, B; Kroll, F; Nakatsutsumi, M; Nitsche, S; Riconda, C; Romagnagni, L; Schlenvoigt, H-P; Simond, S; Veuillot, E; Cowan, T E; Portugall, O; Pépin, H; Fuchs, J

2013-04-01

372

The Use of Ultraviolet Thomson Scattering as a Versatile Diagnostic for Detailed Measurements of a Collisional Laser Produced Plasma.  

NASA Astrophysics Data System (ADS)

Collective Thomson scattering from ion-acoustic waves at 266nm is used to obtain spatially resolved, two -dimensional electron density, sound speed, and radial drift profiles of a collisional laser plasma (critical density, n_{rm c} = 1 times 10^{21} cm^{-3}). An ultraviolet diagnostic wavelength minimizes the complicating effects of inverse bremsstrahlung and refractive turning in the coronal region of interest, where the electron densities approach n_{rm c}/10. Laser plasmas of this type are important because they model some of the aspects of the plasmas found in high-gain laser -fusion pellets irradiated by long pulse widths (t _{rm L} >= 10nsec), where the laser light is absorbed mostly in the corona. The experimental results and LASNEX (Comments Plasma Phys. Controlled Fusion 2, 51 (1975)) simulations agree within a percent standard deviation of 40% for the electron density and 50% for the sound speed and radial drift velocity. Thus it is shown that the hydrodynamics equations with classical coefficients and the numerical approximations in LASNEX are valid models of laser-heated, highly collisional plasmas. The versatility of Thomson scattering is expanded upon by extending existing theory with a Fokker-Planck based model to include plasmas that are characterized by (0 <= k_{rm ia}lambda_{rm ii} <= infty) and ZT_{rm e}/T_{rm i} , where k_{rm ia} is the ion-acoustic wave number, lambda _{rm ii} is the ion-ion mean free path, Z is the ionization state of the plasma, and T_{rm e}, T _{rm i} are the electron and ion temperatures in electron volts (eV), respectively. The model is valid for plasmas in which the electrons are approximately collisionless (k_{rm ia} lambda_{rm ei},k _{rm ia}lambda_{ rm ee} >= 1), and quasineutrality holds, (alpha gg 1), where alpha = 1/klambda_ {rm DE} and lambda _{rm DE} is the electron Debye length. This newly developed model predicts the lineshape of the ion-acoustic Thomson spectra and when fit to experimental data provides a direct measurement of the relative thermal flow velocity between the electrons and ions. The model also correctly predicts the appearance of a zero-frequency or entropy peak in the Thomson spectra in the ion-ion collisional limit.

Tracy, Mark David

1993-01-01

373

EBT2 dosimetry of x-rays produced by the electron beam from a Plasma Focus for medical applications  

SciTech Connect

The electron beam emitted from the back of Plasma Focus devices is being studied as a radiation source for intraoperative radiation therapy applications. A Plasma Focus device is being developed to this aim, to be utilized as an x-ray source. The electron beam is driven to impinge on 50 {mu}m brass foil, where conversion x-rays are generated. Measurements with gafchromic film are performed to analyse the attenuation of the x-rays beam and to predict the dose given to the culture cell in radiobiological experiments to follow.

Ceccolini, E.; Mostacci, D.; Sumini, M. [Montecuccolino Nuclear Engineering Laboratory - DIENCA, University of Bologna, via dei Colli 16, I-40136 Bologna (Italy); Rocchi, F. [Montecuccolino Nuclear Engineering Laboratory - DIENCA, University of Bologna, via dei Colli 16, I-40136 Bologna (Italy); UTFISSM-PRONOC, ENEA, via Martiri di Monte Sole 4, I-40129 Bologna (Italy); Tartari, A. [Department of Physics, Ferrara University, via Saragat 1, I-44122 Ferrara (Italy); Mariotti, F. [ENEA, IRP-DOS, via dei Colli 16, I-40136 Bologna (Italy)

2012-09-01

374

Quasi-phase-matching induced enhancement of the groups of high-order harmonics generating in various multi-jet plasmas produced using perforated targets and modulated heating pulses  

NASA Astrophysics Data System (ADS)

Quasi-phase-matching (QPM) of the harmonics of ultrashort pulses in the perforated aluminum, indium, and chromium plasma plumes produced by different techniques is analyzed. We extend our recent studies (2014 J. Phys. B: At. Mol. Opt. Phys. 47 105401) to other plasma ablations and show the advantages of modulated plasma profiles for the harmonic generation. We demonstrate the 20 × growth of QPM-enhanced harmonics in the plasma produced on the perforated aluminum surface. The calculations of plasma concentrations at different delays and distances from ablating targets are presented. We show the tuning of maximally enhanced harmonics using variable excitation of metallic targets at the conditions of QPM, as well as demonstrate the use of a two-color pump of the four-jet indium plasma for enhancement of the harmonics, which were not present in the spectra obtained from the extended indium plasma.

Ganeev, R. A.; Suzuki, M.; Yoneya, S.; Kuroda, H.

2014-11-01

375

A Experimental Investigation of Stimulated Brillouin Scattering in Laser-Produced Plasmas Relevant to Inertial Confinement Fusion  

Microsoft Academic Search

Despite the apparent simplicity of controlled fusion, there are many phenomena which have prevented its achievement. One phenomenon is laser-plasma instabilities. An investigation of one such instability, stimulated Brillouin scattering (SBS), is reported here. SBS is a parametric process whereby an electromagnetic wave (the parent wave) decays into another electromagnetic wave and an ion acoustic wave (the daughter waves). SBS

Keith Stanley Bradley

1993-01-01

376

An experimental investigation of stimulated Brillouin scattering in laser-produced plasmas relevant to inertial confinement fusion  

SciTech Connect

There are many phenomena which have prevented its achievement of controlled fusion. One phenomenon is laser-plasma instabilities. An investigation of one such instability, stimulated Brillouin scattering (SBS), is reported here. SBS is a parametric process whereby an electromagnetic wave (the parent wave) decays into another electromagnetic wave and an ion acoustic wave (the daughter waves). SBS impedes controlled fusion since it can scatter much or all of the incident laser light, resulting in poor drive symmetry and inefficient laser-plasma coupling. It is widely believed that SBS becomes convectively unstable. Convective theory is often invoked to explain experimental observations, even when one or more of the theory's assumptions are violated. The experiments reported not only obeyed the assumptions of the theory, but were also conducted in plasmas with peak densities well below quarter-critical density. This prevented other competing or coexisting phenomena from occurring. These are the first SBS experiments designed to be both a clear test of linear convective theory and pertinent to controlled fusion research. A crucial part of this series of experiments was the development of a new instrument, the Multiple Angle Time Resolving Spectrometer (MATRS). MATRS has the unique capability of both spectrally and temporally resolving absolute levels of scattered light at many angles simultaneously, and is the first of its kind used in laser-plasma experiments. A detailed comparison of the theoretical predictions and the experimental observations is made. There are qualitative and quantitative differences in the levels of scattered light, as well as the shapes of the spectra and the evolutions of the peak scattered power. Several possible mechanisms are considered to explain these discrepancies. The theory may fail to predict the observations because it does not incorporate many of the plasma details, as well as the early-time (non-steady-state) behavior of SBS.

Bradley, K.S.

1993-01-01

377

An experimental investigation of stimulated Brillouin scattering in laser-produced plasmas relevant to inertial confinement fusion  

SciTech Connect

Despite the apparent simplicity of controlled fusion, there are many phenomena which have prevented its achievement. One phenomenon is laser-plasma instabilities. An investigation of one such instability, stimulated Brillouin scattering (SBS), is reported here. SBS is a parametric process whereby an electromagnetic wave (the parent wave) decays into another electromagnetic wave and an ion acoustic wave (the daughter waves). SBS impedes controlled fusion since it can scatter much or all of the incident laser light, resulting in poor drive symmetry and inefficient laser-plasma coupling. It is widely believed that SBS becomes convectively unstable--that is, it grows as it traverses the plasma. Though it has yet to be definitively tested, convective theory is often invoked to explain experimental observations, even when one or more of the theory`s assumptions are violated. In contrast, the experiments reported here not only obeyed the assumptions of the theory, but were also conducted in plasmas with peak densities well below quarter-critical density. This prevented other competing or coexisting phenomena from occurring, thereby providing clearly interpretable results. These are the first SBS experiments that were designed to be both a clear test of linear convective theory and pertinent to controlled fusion research. A crucial part of this series of experiments was the development of a new instrument, the Multiple Angle Time Resolving Spectrometer (MATRS). MATRS has the unique capability of both spectrally and temporally resolving absolute levels of scattered light at many angles simultaneously, and is the first of its kind used in laser-plasma experiments. A detailed comparison of the theoretical predictions and the experimental observations is made.

Bradley, K.S. [Univ. of California, Davis, CA (US)] [Univ. of California, Davis, CA (US)

1993-02-11

378

Femtosecond-laser-produced low-density plasmas in transparent biological media: a tool for the creation of chemical, thermal, and thermomechanical effects below the optical breakdown threshold  

NASA Astrophysics Data System (ADS)

The irradiance threshold for femtosecond optical breakdown in aqueous media is approximately equals 1.0x1013W cm-2. At the breakdown threshold, a plasma with a free electron density of about 1021cm-3 is generated, and the energy density in the breakdown region is sufficiently high to cause the formation of a bubble which can be experimentally observed. We found previously that plasmas with a free electron density <1021cm-3 are formed also in a fairly large irradiance range below the breakdown threshold. The present study investigates the chemical, thermal, and thermomechanical effects produced by these low-density plasmas. We use a rate equation model considering multiphoton ionization and produced by these low-density plasmas. We use a rate equation model considering multiphoton ionization and avalanche ionization to numerically simulate the temporal evolution of the free electron density during the laser pulse for a given irradiance, and to calculate the irradiance dependence of the free-electron density and volumetric energy density reached at the end of the laser pulse. The value of the energy density created by each laser pulse is then used to calculate the temperature distribution in the focal region after application of a single laser pulse and of series of pulses. The results of the temperature calculations yield, finally, the starting point for calculations of the thermoelastic stresses that are generated during the formation of the low-density plasmas. We found that, particularly for short wavelengths, a large 'tuning range' exists for the creation of spatially extremely confined chemical, thermal and mechanical effects via free electron generation through nonlinear absorption. Photochemical effects dominate at the lower end of this irradiance range, whereas at the upper end they are mixed with thermal effects and modified by thermoelastic stresses. Above the breakdown threshold, the spatial confinement is partly destroyed by cavitation bubble formation, and the laser-induced effects become more disruptive. Our simulations revealed that the highly localized ablation of intracellular structures and intranuclear chromosome dissection recently demonstrated by other researchers are probably mediated by free-electron- induced chemical bond breaking and not related to heating or thermoelastic stresses. We conclude that low density plasmas below the optical breakdown threshold can be a versatile tool for the manipulation of transparent biological media and other transparent materials. (enabling, e.g., the generation of optical waveguides in bulk glass). Low density plasmas may, however, also be a potential hazard in multiphoton microscopy and higher harmonic imaging.

Vogel, Alfred; Noack, Joachim; Huettmann, Gereon; Paltauf, Guenther

2002-04-01

379

Specific in situ visualization of plasma cells producing antibodies against Porphyromonas gingivalis in gingival radicular cyst: application of the enzyme-labeled antigen method.  

PubMed

The enzyme-labeled antigen method was applied to visualize plasma cells producing antibodies to Porphyromonas gingivalis, flora of the human oral cavity. Antibodies to P. gingivalis have reportedly been detected in sera of patients with periodontitis. Biotinylated bacterial antigens, Ag53, and four gingipain domains (Arg-pro, Arg-hgp, Lys-pro, and Lys-hgp) were prepared by the cell-free protein synthesis system using the wheat germ extract. In paraformaldehyde-fixed frozen sections of rat lymph nodes experimentally immunized with Ag53-positive and Ag53-negative P. gingivalis, plasma cells were labeled with biotinylated Arg-hgp and Lys-hgp. Antibodies to Ag53 were detected only in the nodes immunized with Ag53-positive bacteria. In two of eight lesions of gingival radicular cyst with inflammatory infiltration, CD138-positive plasma cells in frozen sections were signalized for Arg-hgp and Lys-hgp. An absorption study using unlabeled antigens confirmed the specificity of staining. The AlphaScreen method identified the same-type antibodies in tissue extracts but not in sera. Antibodies to Ag53, Arg-pro, and Lys-pro were undetectable. In two cases, serum antibodies to Arg-hgp and Lys-hgp were AlphaScreen positive, whereas plasma cells were scarcely observed within the lesions. These findings indicate the validity of the enzyme-labeled antigen method. This is the very first application of this novel histochemical technique to human clinical samples. PMID:21525188

Tsuge, Shinya; Mizutani, Yasuyoshi; Matsuoka, Kazuhiro; Sawasaki, Tatsuya; Endo, Yaeta; Naruishi, Koji; Maeda, Hiroshi; Takashiba, Shogo; Shiogama, Kazuya; Inada, Ken-Ichi; Tsutsumi, Yutaka

2011-07-01

380

A Experimental Investigation of Stimulated Brillouin Scattering in Laser-Produced Plasmas Relevant to Inertial Confinement Fusion  

NASA Astrophysics Data System (ADS)

Despite the apparent simplicity of controlled fusion, there are many phenomena which have prevented its achievement. One phenomenon is laser-plasma instabilities. An investigation of one such instability, stimulated Brillouin scattering (SBS), is reported here. SBS is a parametric process whereby an electromagnetic wave (the parent wave) decays into another electromagnetic wave and an ion acoustic wave (the daughter waves). SBS impedes controlled fusion since it can scatter much or all of the incident laser light, resulting in poor drive symmetry and inefficient laser-plasma coupling. It is widely believed that SBS becomes convectively unstable--that is, it grows as it traverses the plasma. Though it has yet to be definitively tested, convective theory is often invoked to explain experimental observations, even when one or more of the theory's assumptions are violated. In contrast, the experiments reported here not only obeyed the assumptions of the theory, but were also conducted in plasmas with peak densities well below quarter -critical density. This prevented other competing or coexisting phenomena from occurring, thereby providing clearly interpretable results. These are the first SBS experiments that were designed to be both a clear test of linear convective theory and pertinent to controlled fusion research. A crucial part of this series of experiments was the development of a new instrument, the Multiple Angle Time Resolving Spectrometer (MATRS). MATRS has the unique capability of both spectrally and temporally resolving absolute levels of scattered light at many angles simultaneously, and is the first of its kind used in laser-plasma experiments. A detailed comparison of the theoretical predictions and the experimental observations is made. It is determined that there are significant qualitative and quantitative differences in the levels of scattered light, as well as the shapes of the spectra and the evolutions of the peak scattered power. Several possible mechanisms are considered to explain these discrepancies. It is believed that the theory fails to predict the observations because it does not incorporate many of the plasma details, as well as the early-time (non-steady-state) behavior of SBS.

Bradley, Keith Stanley

381

Variation of harmonic spectra in laser-produced plasmas at variable phase of femtosecond laser pulses of different bandwidth  

SciTech Connect

The intensity enhancement of harmonics and change in harmonic profiles have been observed in a few plasma plumes (La, In, Mn) under variable phase modulation of Ti:sapphire laser pulses. It is seen that variation of relative harmonic intensities in the plateau region could be achieved by chirp variation of narrowband ({approx}10 nm bandwidth) radiation. The effect of the self-phase modulation (SPM) of broadband ({approx}20 nm bandwidth) laser radiation on the harmonic emission from nanoparticles, C{sub 60}, and Ag plasma while passing through a glass slab is also studied. The observation of broadband harmonic emission and redshift in harmonic wavelengths for an unchirped laser pulse are explained in terms of SPM. The observation of blueshift of harmonic radiation with both positively and negatively chirped pulses was attributed to the different effects of SPM on the chirped pulses.

Ganeev, R. A. [Raja Ramanna Centre for Advanced Technology, Indore 452013 (India); Institute of Electronics, Uzbekistan Academy of Sciences, Akademgorodok, 33, Dormon Yoli Street, Tashkent 100125 (Uzbekistan); Institute for Solid State Physics, University of Tokyo, 5-1-5 Kashiwanoha, Kashiwa, Chiba 277-8581 (Japan); Singhal, H.; Naik, P. A.; Chakera, J. A.; Tayyab, M.; Gupta, P. D. [Raja Ramanna Centre for Advanced Technology, Indore 452013 (India); Baba, M.; Kuroda, H. [Institute of Electronics, Uzbekistan Academy of Sciences, Akademgorodok, 33, Dormon Yoli Street, Tashkent 100125 (Uzbekistan)

2009-11-15

382

Effect of niobium on the microstructure and wear resistance of iron-based alloy coating produced by plasma cladding  

Microsoft Academic Search

The iron-based alloy coatings have been deposited on plain steel using plasma cladding technique. The effects of niobium element on the microstructure and wear resistance property of the iron-based coatings were investigated using scanning electron microscopy (SEM) with energy dispersive spectrum (EDS), X-ray diffraction (XRD) and ball-on-disc wear tester. Results showed that there were ?-(Fe,Ni) austenite and lots of compounds

Limin Zhang; Dongbai Sun; Hongying Yu

2008-01-01

383

Efficient X-ray short pulse generation from femtosecond laser-produced plasma for pump-probe spectroscopy  

Microsoft Academic Search

X-rays emitted from high-density plasmas created by femtosecond laser pulses are of great interest. Since such X-rays are synchronized to the laser pulse, these sources in the short pulse regime are expected to provide high temporal resolution in X-ray diffraction, absorption spectroscopy, and other applications used to measure the dynamic processes in optically excited materials. In this paper, we describe

H. Nakano; T. Nishikawa; K. Oguri; N. Uesugi

2000-01-01

384

X-ray spectroscopy of a thin foil plasma produced by a short-pulse high-intensity laser  

Microsoft Academic Search

High density and temperature plasmas have been generated by irradiating thin foils of various elements with a high-energy subpicosecond laser pulse. The X-ray emission duration was studied by time-resolved X-ray spectroscopy. Frequency domain interferometry provided a measurement of the hydrodynamic expansion of the back of the foil as a function of time. The effect of longitudinal temperature gradients, i.e., gradients

P. Audebert; V. Nagels; J. P. Geindre; F. Dorchies; O. Peyrusse; S. Gary; F. Girard; R. Shepherd; J. C. Gauthier; C. Chenais-Popovics

2003-01-01

385

Analytical theory of charge-exchange-caused dips in spectral lines of He-like ions from laser-produced plasmas  

NASA Astrophysics Data System (ADS)

Previously we discovered a way for producing not-yet-available fundamental data on charge exchange between multicharged ions, virtually inaccessible by other experimental methods. It was based on the formation of dips (called x-dips) in spectral lines of hydrogen-like ions from laser-produced plasmas. At that time the x-dip phenomenon was considered to be possible only in spectral lines of hydrogenic systems: due to the existence of exact algebraic (higher than geometrical) symmetries relevant only to hydrogenic systems and to the corresponding two-Coulomb-centre systems (dicentres) having one electron. In the present paper, by engaging the concept of an approximate algebraic symmetry of two-electron dicentres (and of helium-like ions), we opened up the way to significantly broaden the scope of experimental studies of the x-dip phenomenon—to studies of possible x-dips in spectral line profiles emitted by He-like ions in laser-produced plasmas. We identified three prospective two-electron dicentres and calculated analytically theoretical positions of the x-dips in the corresponding He-like spectral lines (though future experimental and theoretical studies should not be limited to these three two-electron dicentres). Since future experimental and theoretical studies should not be limited to these three two-electron dicentres, we presented also a table containing 15 prospective He-like spectral lines and 10 corresponding solid targets for observing x-dips in laser-produced plasmas. For completeness we presented also a similar table for H-like lines. It presented 16 prospective H-like spectral lines and 11 corresponding solid targets for observing x-dips in laser-produced plasmas. From the shape of experimental x-dips it is possible to determine the rate coefficient of charge exchange in the corresponding dicentre, as demonstrated previously. Therefore the results of the present paper should very significantly extend the range of fundamental data on charge exchange between multicharged ions that can be obtained via the x-dip phenomenon, but not by any other method.

Dalimier, E.; Oks, E.

2014-05-01

386

A proposed technique for creation and detection of hot electron ionization and gain effects in a laser-produced tin plasma  

NASA Astrophysics Data System (ADS)

It has recently been demonstrated that suprathermal electrons, while deleterious to laser fusion, may have significant and beneficial effects in plasma ionization and promoting population inversions in neon-like ions. This report considers experimental demonstration of these effects. Using linearly focused and aligned beams, a series of shots with planar in tin targets (Z=50) is proposed. At irradiances of approx. = 1-4 X 10 to the 14th power W 1/cm, both the energies and numbers of hot electrons produced by a 1.05 micron laser beam should be appropriate for substantial enhancement of gain in the 3s-3p transition of neon-like tin at 118.2A. If possible a quiescent plasma should be prepared with a 0.35 micron beam, which would be followed by a 1.05 micron pulse to create a burst of hot electrons at 4-5 keV to pump the upper leasing state.

Apruzese, J. P.; Davis, J.

1984-07-01

387

Microstructure and wear properties of WC particle reinforced composite coating on Ti6Al4V alloy produced by the plasma transferred arc method  

NASA Astrophysics Data System (ADS)

The microstructure and wear properties of a WC particle reinforced composite coating produced by the plasma transferred arc (PTA) method on Ti6Al4V alloy were investigated in this study. PTA processing was carried out using argon as the plasma gas at arc current values of 70 A, 80 A and 90 A. Scanning electron microscopy (SEM), X-ray energy dispersive spectroscopy (EDS) and X-ray diffraction (XRD) were used to characterize the microstructure of the composite layer formed on the surface of a Ti6Al4V substrate. The results indicate that the WC, TiC and W2C carbide phases formed in the composite layers produced by PTA on the surface of the Ti6Al4V alloy. The distributions and volume fractions of these phases were found to vary with the arc current values. Wear tests were performed under dry sliding conditions using a linear ball-on-disc geometry. The microhardness and wear resistances of all of the composite layers produced by the PTA process were enhanced relative to those of the Ti6Al4V substrate. The homogeneity and volume fractions of the carbide phases in the composite layers were responsible for the improvement in the wear resistance of the alloy. The wear test results indicate that the alloy modified at 70 A shows better wear resistance than the alloys modified at 80 A and 90 A.

Çelik, Osman Nuri

2013-06-01

388

The impact of low-Z impurities on x-ray conversion efficiency from laser-produced plasmas of low-density gold foam targets  

SciTech Connect

It is an important approach to improve the x-ray conversion efficiency of laser-ablated high-Z plasmas by using low initial density materials for various applications. However, unavoidable low-Z impurities in the manufacture process of low-density high-Z foam targets will depress this effect. A general easy-to-use analytical model based on simulations was developed to evaluate the quantitative impact of impurities within the gold foam target on laser to x-ray conversion efficiency. In addition, the x-ray conversion efficiencies of 1 g/cm{sup 3} gold foams with two different initial contents of impurities were experimentally investigated. Good agreements have been achieved between the model results and experiments.

Dong, Yunsong [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China) [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Department of Engineering Physics, Tsinghua University, Beijing 100084 (China); Shang, Wanli; Yang, Jiamin; Zhang, Lu; Zhang, Wenhai; Li, Zhichao; Guo, Liang; Zhan, Xiayu; Du, Huabing; Deng, Bo [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China)] [Research Center of Laser Fusion, China Academy of Engineering Physics, Mianyang 621900 (China); Pu, Yikang [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China)] [Department of Engineering Physics, Tsinghua University, Beijing 100084 (China)

2013-12-15

389

Spectroscopic investigations of hard x-ray emission from 120 ps laser-produced plasmas at intensities near 10{sup 17} W cm{sup {minus}2}  

SciTech Connect

Spectroscopic investigations of the x-ray emission of plasmas heated by 120 ps, frequency doubled pulses from the JANUS Nd: glass laser are presented. High Z K-shell spectra emitted from slab targets heated to near 10{sup 17} W cm{sup {minus}2} intensity are investigated. High resolution ({gamma}/{Delta}{gamma}>5000) x-ray spectra of multicharged ions of H-like Ti, Co, Ni, Cu, and also H-like Sc in the spectral range 1.5--3.0 {angstrom} are obtained in single laser shots using a spherically bent Mica crystal spectrograph with a 186 mm radius of curvature. The spectra- have one dimensional spatial resolution of about 25{mu}m and indicate that the size of the emission zone of the resonance, transitions is <25{mu}m. Simultaneous x-ray images of the plasma from a charge-coupled device pinhole camera confirmed that the plasma x-ray emission is from a similar sized source. Survey spectra {gamma}/{Delta}{gamma}=500--1000) taken with a flat LiF (200) crystal spectrometer with a charge-coupled device detector complement the high resolution data. Two dimensional LASNEX modeling of the laser target conditions indicate that the high K-shell charge states are produced in the hot dense region of the plasma with electron temperature >2 keV and density{approximately}10{sup 22} cm{sup {minus}3}. These experiments demonstrate that with modest laser energy, plasmas heated by high-intensity 120 ps lasers provide a very bright source of hard {approximately}8 keV x-ray emission.

Dunn, J.; Young, B.K.F.; Osterheld, A.L.; Foord, M.E.; Walling, R.S.; Stewart, R.E. [Lawrence Livermore National Lab., CA (United States); Faenov, A.Y. [VINIFTRI, Mendeleevo, Moscow Region (Russian Federation)

1995-11-01

390

APPLICATIONS OF LASERS AND OTHER TOPICS IN QUANTUM ELECTRONICS: Mass spectra of multiply charged ions in a laser produced plasma  

NASA Astrophysics Data System (ADS)

The mass spectrometric method was used in an experimental investigation of the fast ions in a plasma generated using moderate laser radiation power densities (q = 1010-1012 W/cm2). It was found that, for power densities of (q app_gt.gif 0.5 TW/cm2 and p-polarized laser radiation incident at angles of ? = 18 ± 5°, two groups of ions appeared and these differed in both energy and charge multiplicity. For q = 1 TW/cm2 the ion velocity was ~ 108 cm/s.

Bedilov, M. R.; Kholbaev, A.

1988-01-01

391

INTERACTION OF LASER RADIATION WITH MATTER: Highly stable plasma source produced on the liquid-gallium surface by a femtosecond laser pulse  

NASA Astrophysics Data System (ADS)

Experimental results are presented which demonstrate that a plasma produced on the melted-gallium surface by a femtosecond laser pulse of intensity above 1016 W cm-2 is an efficient and stable source of incoherent hard X-rays with a pulse repetition rate of 10 Hz. For gallium heated up to 270°C, the X-ray yield decreased by ~25% [from (2.2 ± 0.4) × 10-4 % to (1.7 ± 0.4) × 10-4 %] after 50000 laser shots, while the average energy of hot electrons decreased from 9.3 ± 0.9 to 9.0 ± 1.1 keV.

Gordienko, Vyacheslav M.; Kurilova, M. V.; Rakov, Evegenii V.; Savel'ev, Andrei B.; Uryupina, D. S.

2007-07-01

392

Singled-walled carbon nanotubes produced by induction thermal plasma: Cytotoxicity evaluation of the feedstock materials and the final product for a potential bone application  

NASA Astrophysics Data System (ADS)

One of the most challenging issues that the technologies related to nanomaterials face is the impact they have on human health and environment. It is therefore of great importance to investigate the toxicological impacts of these technologies prior to their widespread utilization in different fields of application. Therefore, in this study, the cytotoxicity of the materials present throughout the process of single-walled carbon nanotubes (SWCNTs) synthesis by induction thermal plasma (from the feedstock materials to the final product) was evaluated. First of all, the influence of the induction thermal plasma process on the physico-chemical and cytotoxic properties of feedstock materials (i.e. commercial Co, Ni, Y2O3, Mo catalysts and carbon black) was investigated. The strongest cytotoxicity was observed for commercial Co compared to other catalysts. Although the thermal plasma process affected the properties of all catalysts, only the cytotoxicity of Ni was increased. Comparing the properties and cytotoxicity of the plasma treated Ni particles with commercial Ni nanoparticles revealed that the particles with similar surface area had different cytotoxicities. Plus, the observed cytotoxicity of the catalysts was not mainly due to the release of ions. In order to evaluate the capacity of the RF induction thermal plasma process to produce high quality SWCNTs using non-toxic catalysts, the effects of the type and quantity of three catalyst mixtures (Ni-Y2O 3, Ni-Co-Y2O3, and Ni-Mo-Y2O3 ) on SWCNTs synthesis were examined. Thermodynamic calculations, in gas and particularly in liquid solution phases, were also performed. The results showed that catalyst type affected the quality of the SWCNT final product and similar quality SWCNTs was produced when the same amount of Co was replaced by Ni. Then, to investigate the cytotoxicity of the SWCNTs produced with the three catalyst mixtures, their effect was evaluated on the behavior of murine MC3T3-E1 preosteoblasts. Either SWCNTs were added on the attached cells or cells were seeded on the SWCNT-covered culture plates. SWCNTs which were added on the attached cells reduced cell viability drastically in a dose-dependent manner. However, the viability of the cells seeded on SWCNTs was only slightly decreased at 24 h, even on those produced with Ni-Co-Y2O3 . Moreover, cells could proliferate within 48 h. Thus, except mechanical membrane disturbance, thermal plasma grown SWCNTs seemed to induce no severe cytotoxicity on MC3T3-E1 preosteoblasts. Consequently, SWCNTs were purified and their influence on the viability and proliferation of MC3T3-E1 preosteoblasts was determined. The impact of SWCNTs on Smad activation and cell differentiation induced by BMP-2 and BMP-9 was also studied. SWCNTs pre-treatment accelerated the Smad1/5/8 activation induced by both BMP-2 and BMP-9. It did not reduce the viability of preosteoblasts but slightly affected their proliferation at 48 h. Furthermore, after 72 h incubation with BMP-2 or BMP-9, preosteoblasts pre-treated with SWCNTs for 24 h could express genes encoding osteogenic markers such as osterix and osteocalcin and showed high alkaline phosphatase activity. Interestingly, BMP-9 favored the differentiation of preosteoblasts pre-treated with SWCNTs more remarkably than BMP-2. Therefore, combination of BMP-9 with SWCNTs seems to be a promising avenue for bone regeneration. Keywords: Carbon nanotubes, metallic nanoparticles, induction thermal plasma, cytotoxicity, cell proliferation, mitochondrial enzymatic activity, lactate dehydrogenase, osteogenesis.

Alinejad, Yasaman

393

Synthesis and investigation of reaction mechanisms of diamondoids produced using plasmas generated inside microcapillaries in supercritical xenon  

NASA Astrophysics Data System (ADS)

We have synthesized diamondoids using dielectric barrier discharge microplasmas generated inside a microcapillary reactor in supercritical xenon. The plasmas were generated near the critical temperature (T_{\\text{crit}} = 389.75\\,\\text{K}) and pressure (p_{\\text{crit}} = 5.84\\,\\text{MPa}) of xenon in the ranges of T/T_{\\text{crit}} = 0.964-0.983 and p/p_{\\text{crit}} = 0.998\\text-1.026 under both batch-type and continuous flow conditions with gas flow rates of 0.01-0.5 mL min-1. Micro-Raman spectra of the synthesized particles showed features characteristic of diamondoids, while gas chromatography-mass spectrometry measurements revealed that diamondoids up to undecamantane were possibly synthesized. Further, the amount of obtained diamantane was greater than those obtained using previously reported diamondoid synthesis processes that involve plasmas in supercritical fluids. This increase is attributed to the higher solubility of the supercritical medium, i.e., xenon, and the higher efficiency of the microreactor. A detailed gas chromatography-mass spectrometry analysis showed that higher diamondoids grow in a stepwise manner via the alternate removal of hydrogen atoms and the addition of methyl groups.

Oshima, Fumito; Stauss, Sven; Inose, Yoshifumi; Terashima, Kazuo

2014-01-01

394

Measurement of attractive interactions produced by the ion wakefield in dusty plasmas using a constrained collision geometry.  

PubMed

Plasma dust particle interactions, charges, and screening lengths are derived from measurements of time-dependent particle positions in a simplified geometry. The magnitude and structure of the ion wakefield potential below a negatively charged dust particle levitated in the plasma sheath region were measured as functions of the pressure and interparticle spacing. Attractive and repulsive components of the interaction force were extracted from a trajectory analysis of low-energy dust collisions between different mass particles in a well-defined electrostatic potential that constrained the dynamics of the collisions to be one-dimensional. Typical peak attractions varied between 60 and 230 fN while the peak particle-particle repulsion was on the order of 60 fN. Random thermal motion of the particles contributed to observable rates for transitions between different equilibrium configurations of vertically separated particles. The influence of nearest- and non-nearest-neighbor interactions on calculated particle parameters is examined using several methods. PMID:14683048

Hebner, G A; Riley, M E

2003-10-01

395

PHYSIOLOGICAL RISE IN PLASMA LEUCINE STIMULATES MUSCLE PROTEIN SYNTHESIS IN NEONATAL PIGS BY ENHANCING TRANSLATION INITIATION FACTOR ACTIVATION  

Technology Transfer Automated Retrieval System (TEKTRAN)

Protein synthesis in skeletal muscle of adult rats increases in response to oral gavage of supraphysiological doses of leucine. However, the effect on protein synthesis of a physiological rise in plasma leucine has not been investigated in neonates, an anabolic population highly sensitive to amino a...

396

Drift wave and its stability analysis in ECR produced plasma of MaPLE device at Saha Institute of Nuclear Physics  

NASA Astrophysics Data System (ADS)

Cross-field transport due to the low frequency drift modes destroys the plasma confinement [W. Horton, Rev. Mod. Phys. 71, 735(1999)] and is one of the main barriers to achieve thermonuclear power in nuclear fusion. In the present experiment with the MaPLE (Magnetized Plasma Linear Experimental) device [R. Pal, S. Biswas et. al., Rev. Sci. Instrum. 81, 73507(2011)] where plasma is produced by Electron Cyclotron Resonance (ECR) method using 2.45 GHz microwave, modulation of density at 300 Hz excites the drift wave in its second harmonic. Measurement of poloidal propagation and density gradient scale length confirms it to be a drift wave with mode number m=2. Stability analysis shows that parallel electron flow excites this mode. Growth rate also depends on magnetic field value. At a critical magnetic field value, the growth rate is maximum. Parametric couple of this mode with 300 Hz mode also excites 900 Hz mode. Details results will be presented.

Biswas, Subir; Pal, Rabindranath; Chakrabarti, Nikhil

2012-10-01

397

Open field equilibrium current and cross-field passing electrons as an initiator of a closed flux surface in EC-heated toroidal plasmas  

NASA Astrophysics Data System (ADS)

A model for the non-inductive initiation of a closed flux surface observed in electron cyclotron (EC) heated toroidal plasmas is presented. First, a pressure-driven equilibrium toroidal current develops under a weak external vertical field so as to counter balance the pressure-ballooning and current-hoop forces. When the self-field from the current almost cancels out the external vertical field, a forward energetic part of electrons in the velocity space begins to make cross-field passing (CFP) orbits. The CFP electrons are generated by the EC heating of bulk electrons and subsequent pitch-angle scattering, which is analyzed using the Fokker-Planck equation. They provide an additional current that closes the field lines. The model is examined for experiments in the small low aspect ratio device of LATE and in the large conventional device of JT-60U with a search for appropriate modes of EC heating. Simultaneous coincidence of the model with these two experiments is obtained in terms of microwave power and driven current. The results predict that initiation of a closed flux surface requires more and more EC power as the plasma major radius increases. In particular, careful injection of high N? EC waves is needed for large devices, both for initiation of a closed flux surface and for subsequent enlargement of the flux surface by the usual EC current drive onto the closed flux area.

Maekawa, T.; Yoshinaga, T.; Uchida, M.; Watanabe, F.; Tanaka, H.

2012-08-01

398

Research on anisotropy of fusion-produced protons and neutrons emission from high-current plasma-focus discharges  

NASA Astrophysics Data System (ADS)

The paper concerns fast protons and neutrons from D-D fusion reactions in a Plasma-Focus-1000U facility. Measurements were performed with nuclear-track detectors arranged in "sandwiches" of an Al-foil and two PM-355 detectors separated by a polyethylene-plate. The Al-foil eliminated all primary deuterons, but was penetrable for fast fusion protons. The foil and first PM-355 detector were penetrable for fast neutrons, which were converted into recoil-protons in the polyethylene and recorded in the second PM-355 detector. The "sandwiches" were irradiated by discharges of comparable neutron-yields. Analyses of etched tracks and computer simulations of the fusion-products behavior in the detectors were performed.

Malinowski, K.; Skladnik-Sadowska, E.; Sadowski, M. J.; Szydlowski, A.; Czaus, K.; Kwiatkowski, R.; Zaloga, D.; Paduch, M.; Zielinska, E.

2015-01-01

399

Research on anisotropy of fusion-produced protons and neutrons emission from high-current plasma-focus discharges.  

PubMed

The paper concerns fast protons and neutrons from D-D fusion reactions in a Plasma-Focus-1000U facility. Measurements were performed with nuclear-track detectors arranged in "sandwiches" of an Al-foil and two PM-355 detectors separated by a polyethylene-plate. The Al-foil eliminated all primary deuterons, but was penetrable for fast fusion protons. The foil and first PM-355 detector were penetrable for fast neutrons, which were converted into recoil-protons in the polyethylene and recorded in the second PM-355 detector. The "sandwiches" were irradiated by discharges of comparable neutron-yields. Analyses of etched tracks and computer simulations of the fusion-products behavior in the detectors were performed. PMID:25638081

Malinowski, K; Skladnik-Sadowska, E; Sadowski, M J; Szydlowski, A; Czaus, K; Kwiatkowski, R; Zaloga, D; Paduch, M; Zielinska, E

2015-01-01

400

Increasing the output power of single 808-nm laser diodes using diamond submounts produced by microwave plasma chemical vapour deposition  

SciTech Connect

We have designed and fabricated submounts from synthetic diamond grown by microwave plasma chemical vapour deposition and developed an economical process for metallising such submounts. Laser diode chips having an 808-nm emission wavelength, 3-mm-long cavity and 130-mm-wide stripe contact were mounted on copper heat sinks with the use of diamond submounts differing in quality. The devices were tested for more than 150 h in continuous mode at an output power of 8 W on diamond with a thermal conductivity of 700 W m{sup -1} K{sup -1}, and no changes in their output power were detected. On diamond with a thermal conductivity of 1600 W m{sup -1} K{sup -1}, stable cw operation for 24 h at an output power of 12 W was demonstrated. (letters)

Ashkinazi, E E; Bezotosnyi, V V; Bondarev, Vadim Yu; Kovalenko, V I; Konov, Vitalii I; Krokhin, Oleg N; Oleshchenko, V A; Pevtsov, Valerii F; Popov, Yurii M; Popovich, A F; Ral'chenko, Viktor G; Cheshev, E A

2012-11-30

401

A comparative study of the inner-shell and the ionic line radiation from ultra-short laser-produced magnesium plasma  

NASA Astrophysics Data System (ADS)

The inner-shell radiation (K-?) and the ionic line radiation (He-?) from magnesium plasma, generated by the interaction of a 3 TW, 45 fs laser, have been studied simultaneously using an x-ray crystal spectrograph. The effect of the variation of the laser intensity and its offset from the best focus position has been studied. He-? and K-? x-ray yields are found to scale with the laser intensity as IL1.5 and IL0.6 respectively. The K-? x-ray conversion shows a maximum at the best focus and reduces symmetrically on either side of the best focus position, whereas the He-? conversion peaks when the target is placed before the focused laser beam. The angular distribution for the He-? as well as the K-? emissions shows a maximum in the forward direction and the intensity reduces with the increase in angle ? with respect to the target normal as cos? ?. The value of ? is 0.7 and 3 for He-? and K-? respectively. The experimentally observed variation of the He-? line conversion for different laser parameters has been explained by considering the change in preformed plasma conditions, and the variation in the K-? emission has been explained by considering hot electron generation and their propagation in the bulk solid target. The plasma conditions prevalent during the emission of the x-ray spectrum were identified by comparing the experimental spectra with the synthetic spectra generated using the spectroscopic analysis code PrismSPECT. The results will be useful in designing laser-produced plasma x-ray line radiation sources of photon energy in the range of 1–2 keV, for its potential use as a probe pulse in x-ray backlighting, or time-resolved x-ray diffraction studies.

Arora, Vipul; Anant Naik, Prasad; Chakravarty, Uday; Singhal, Himanshu; Sanyasi Rao, Bobbili; Chakera, Juzer Ali; Prasad Singh, Manoranjan; Dass Gupta, Parshottam

2014-11-01

402

Characteristics of a cylindrical collector mirror for laser-produced xenon plasma soft X-rays and improvement of mirror lifetime by buffer gas  

SciTech Connect

The focusing characteristics of a ruthenium-coated cylindrical mirror were investigated on the basis of its ability to collect and focus broadband 5-17-nm soft X-rays emitted from a laser-produced plasma. Based on the plasmas spectral intensity distribution and the reflectivity function of the mirror, we defined the optimum position of the integrated cylindrical mirror at which the X-ray energy flux transported and focused through the mirror was maximum. A minimum spot diameter of 22 mm at a distance of approximately 200 mm from a soft X-ray source was confirmed. The maximum intensity of the collected soft X-rays was 1.3 mJ/cm{sup 2} at the center of the irradiation zone. Thus, the irradiation intensity was improved by approximately 27 times when compared to that of 47 {mu}J/cm{sup 2} without the mirror. The debris sputtering rate on the reflection surface of the mirror can be reduced to 1/110 by argon gas at 11 Pa, while the attenuation rate of the soft X-rays due to absorption by the buffer gas can be suppressed to less than 10% at the focal point. The focusing property of the mirror is expected to be maintained for 3000 h or longer without significant degradation for a 100 W/320 pps laser shot if the ruthenium layer is thicker than 10 {mu}m. These results suggest that a stand-alone broadband soft X-ray processing system can be realized by using laser-produced plasma soft X-rays.

Inoue, Tomoaki; Mochizuki, Takayasu; Miyamoto, Shuji; Masuda, Kazuya; Amano, Sho; Kanda, Kazuhiro [Laboratory of Advanced Science and Technology for Industry, University of Hyogo, 3-1-2 Kouto, Kamigori, Ako-gun, Hyogo 678-1205 (Japan)

2012-12-15

403

Characteristics of a cylindrical collector mirror for laser-produced xenon plasma soft X-rays and improvement of mirror lifetime by buffer gas  

NASA Astrophysics Data System (ADS)

The focusing characteristics of a ruthenium-coated cylindrical mirror were investigated on the basis of its ability to collect and focus broadband 5-17-nm soft X-rays emitted from a laser-produced plasma. Based on the plasmas spectral intensity distribution and the reflectivity function of the mirror, we defined the optimum position of the integrated cylindrical mirror at which the X-ray energy flux transported and focused through the mirror was maximum. A minimum spot diameter of 22 mm at a distance of approximately 200 mm from a soft X-ray source was confirmed. The maximum intensity of the collected soft X-rays was 1.3 mJ/cm2 at the center of the irradiation zone. Thus, the irradiation intensity was improved by approximately 27 times when compared to that of 47 ?J/cm2 without the mirror. The debris sputtering rate on the reflection surface of the mirror can be reduced to 1/110 by argon gas at 11 Pa, while the attenuation rate of the soft X-rays due to absorption by the buffer gas can be suppressed to less than 10% at the focal point. The focusing property of the mirror is expected to be maintained for 3000 h or longer without significant degradation for a 100 W/320 pps laser shot if the ruthenium layer is thicker than 10 ?m. These results suggest that a stand-alone broadband soft X-ray processing system can be realized by using laser-produced plasma soft X-rays.

Inoue, Tomoaki; Mochizuki, Takayasu; Miyamoto, Shuji; Masuda, Kazuya; Amano, Sho; Kanda, Kazuhiro

2012-12-01

404

Radiofrequency plasma antenna generated by femtosecond laser filaments in air  

SciTech Connect

We demonstrate tunable radiofrequency emission from a meter-long linear plasma column produced in air at atmospheric pressure. A short-lived plasma column is initially produced by femtosecond filamentation and subsequently converted into a long-lived discharge column by application of an external high voltage field. Radiofrequency excitation is fed to the plasma by induction and detected remotely as electromagnetic radiation by a classical antenna.

Brelet, Y.; Houard, A.; Point, G.; Prade, B.; Carbonnel, J.; Andre, Y.-B.; Mysyrowicz, A. [Laboratoire d'Optique Appliquee, ENSTA ParisTech, Ecole Polytechnique, CNRS, 91761 Palaiseau (France); Arantchouk, L. [Laboratoire de Physique des Plasmas, Ecole Polytechnique, CNRS, Palaiseau (France); Pellet, M. [Etat-major de la Marine Nationale, Paris (France)

2012-12-24

405

Initial exposure to 30 kV/m or 60 kV/m 60 Hz electric fields produces temporary cessation of operant behavior of nonhuman primates  

SciTech Connect

In two separate experiments, the authors examined the effects of a 60 Hz electric field (EF) on performance of an operant schedule consisting of two signaled components: fixed-ratio (FR30) and differential reinforcement of low-rate (DRL20). In each experiment, 12 naive baboons (Papio cynocephalus) were assigned randomly to either an EF-exposed experimental group or a sham-exposed control group. A homogeneous vertical EF of 30 kV/m was used in one experiment; 60 kV/m was used in the other. The experimental design for both experiments included 6 week preexposure, exposure, and postexposure periods. The planned analyses indicated no evidence of statistically significant (P < .05) effects of EF exposure. However, exploratory analyses comparing performance during the last week of preexposure and the first week of exposure revealed statistically significant acute effects (work stoppage): The mean response rates of the EF-exposed groups were greatly reduced on day 1 of exposure but were normal by the end of day 2 of EF exposure. The authors hypothesize that introduction of a highly unusual stimulus, the EF, temporarily interfered with normal operant behavior to produce a primary work stoppage. Supplementary cross-over experiments added at the end of each main experiment indicated that work stoppage occurred again when formerly EF-exposed subjects served as sham-exposed controls, while other subjects received their first EF exposure. Presumably, reoccurrence of other stimuli correlated with initial exposure to the EF became sufficient to subsequently cause secondary work stoppage in the absence of direct EF exposure. The primary and secondary work-stoppage effects were reproducible.

Rogers, W.R.; Orr, J.L.; Smith, H.D. [Southwest Research Inst., San Antonio, TX (United States). Biosciences and Bioengineering Dept.

1995-12-31

406

Broadband time-resolved elliptical crystal spectrometer for X-ray spectroscopic measurements in laser-produced plasmas  

NASA Astrophysics Data System (ADS)

The X-ray spectrometer used in high-energy-density plasma experiments generally requires both broad X-ray energy coverage and high temporal, spatial, and spectral resolutions for overcoming the difficulties imposed by the X-ray background, debris, and mechanical shocks. By using an elliptical crystal together with a streak camera, we resolve this issue at the SG-II laser facility. The carefully designed elliptical crystal has a broad spectral coverage with high resolution, strong rejection of the diffuse and/or fluorescent background radiation, and negligible source broadening for extended sources. The spectra that are Bragg reflected (23° < ? < 38°) from the crystal are focused onto a streak camera slit 18 mm long and about 80 ?m wide, to obtain a time-resolved spectrum. With experimental measurements, we demonstrate that the quartz(1011) elliptical analyzer at the SG-II laser facility has a single-shot spectral range of (4.64–6.45) keV, a typical spectral resolution of E/?E = 560, and an enhanced focusing power in the spectral dimension. For titanium (Ti) data, the lines of interest show a distribution as a function of time and the temporal variations of the He-? and Li-like Ti satellite lines and their spatial profiles show intensity peak red shifts. The spectrometer sensitivity is illustrated with a temporal resolution of better than 25 ps, which satisfies the near-term requirements of high-energy-density physics experiments.

Wang, Rui-Rong; Jia, Guo; Fang, Zhi-Heng; Wang, Wei; Meng, Xiang-Fu; Xie, Zhi-Yong; Zhang, Fan

2014-11-01

407

The Verwey transition in nanostructured magnetite produced by a combination of chimie douce and spark plasma sintering  

NASA Astrophysics Data System (ADS)

Magnetite nanoparticles about 10 nm sized were synthesized by the polyol method. Zero-field-cooled (ZFC)-FC measurements showed a blocking temperature ˜170 K and the absence of the Verwey transition. They were subsequently consolidated by spark plasma sintering at 750 °C for 15 min, leading to a high density (92% of the theoretical density), solid body, with grains in the 150 nm range. X-ray diffraction patterns exhibited a spinel single phase with cell parameters corresponding to the magnetite structure. Magnetic measurements showed a decrease of coercivity from 685 Oe (54.5 kA/m) at 118 K to 90 Oe (7.2 kA/m) at 139 K. ZFC measurements at 25 Oe presented a three-fold magnetization increase as temperature increased; a small transition between 116 and 117.5 K, followed by a larger one from 117.6 to 124 K. The first transition can be associated with a complex crystallographic transition and delocalization of Fe2+-Fe3+, while the second one can be attributed to spin reorientation due to the magnetocrystalline anisotropy constant (K1) change of sign as previously observed only in magnetite single crystals.

Gaudisson, T.; Vázquez-Victorio, G.; Bañobre-López, M.; Nowak, S.; Rivas, J.; Ammar, S.; Mazaleyrat, F.; Valenzuela, R.

2014-05-01

408

X-ray spectroscopy of 1 cm plasma channels produced by self-guided pulse propagation in elongated cluster jets.  

PubMed

We diagnose the self-channeled propagation of intense femtosecond pulses over an extended distance in a N2O cluster gas target using high resolution kilovolt x-ray pinhole images of the channel and spatially resolved x-ray spectra. The x-ray images are consistent with femtosecond optical scattering, shadowgraphy, and interferometry images. We observe extended plasma channels (approximately 9 mm) limited either by the cluster jet length or by absorption, for injected laser intensities in the range of 10(16)-10(17) W/cm2. Spectral line shapes for the OVII 1s2-1s3p and OVIII 1s-2p transitions (at 1.8627 and 1.8969 nm, respectively) show significant broadening to the blue side and with truncated emission on the red side. We attribute this effect to Doppler blueshifted emission from fast ions from exploding clusters moving toward the spectrometer; redshifted emission from the opposite side of the cluster is absorbed. PMID:16906984

Kim, K Y; Milchberg, H M; Faenov, A Ya; Magunov, A I; Pikuz, T A; Skobelev, I Yu

2006-06-01

409

The Verwey transition in nanostructured magnetite produced by a combination of chimie douce and spark plasma sintering  

SciTech Connect

Magnetite nanoparticles about 10?nm sized were synthesized by the polyol method. Zero-field-cooled (ZFC)-FC measurements showed a blocking temperature ?170?K and the absence of the Verwey transition. They were subsequently consolidated by spark plasma sintering at 750?°C for 15?min, leading to a high density (92% of the theoretical density), solid body, with grains in the 150?nm range. X-ray diffraction patterns exhibited a spinel single phase with cell parameters corresponding to the magnetite structure. Magnetic measurements showed a decrease of coercivity from 685?Oe (54.5?kA/m) at 118?K to 90?Oe (7.2?kA/m) at 139?K. ZFC measurements at 25?Oe presented a three-fold magnetization increase as temperature increased; a small transition between 116 and 117.5?K, followed by a larger one from 117.6 to 124?K. The first transition can be associated with a complex crystallographic transition and delocalization of Fe{sup 2+}-Fe{sup 3+}, while the second one can be attributed to spin reorientation due to the magnetocrystalline anisotropy constant (K{sub 1}) change of sign as previously observed only in magnetite single crystals.

Gaudisson, T.; Nowak, S.; Ammar, S. [ITODYS, Université Paris Diderot, PRES Sorbonne Paris Cité, CNRS-UMR 7086, 75205 Paris Cedex (France); Vázquez-Victorio, G.; Valenzuela, R., E-mail: raulvale@yahoo.com [Depto Materiales Metálicos y Cerámicos, Instituto de Investigaciones en Materiales, Universidad Nacional Autónoma de México, Mexico 04510 (Mexico); Bañobre-López, M.; Rivas, J. [International Iberian Nanotechnology Laboratory, 4715-310 Braga (Portugal); Mazaleyrat, F. [SATIE, ENS Cachan, CNRS, UniverSud, F-94230 Cachan (France)

2014-05-07

410

Dynamic Contrast-Enhanced MRI Assessment of Hyperemic Fractional Microvascular Blood Plasma Volume in Peripheral Arterial Disease: Initial Findings  

PubMed Central

Objectives The aim of the current study was to describe a method that assesses the hyperemic microvascular blood plasma volume of the calf musculature. The reversibly albumin binding contrast agent gadofosveset was used in dynamic contrast-enhanced magnetic resonance imaging (DCE MRI) to assess the microvascular status in patients with peripheral arterial disease (PAD) and healthy controls. In addition, the reproducibility of this method in healthy controls was determined. Materials and Methods Ten PAD patients with intermittent claudication and 10 healthy control subjects were included. Patients underwent contrast-enhanced MR angiography of the peripheral arteries, followed by one DCE MRI examination of the musculature of the calf. Healthy control subjects were examined twice on different days to determine normative values and the interreader and interscan reproducibility of the technique. The MRI protocol comprised dynamic imaging of contrast agent wash-in under reactive hyperemia conditions of the calf musculature. Using pharmacokinetic modeling the hyperemic fractional microvascular blood plasma volume (Vp, unit: %) of the anterior tibial, gastrocnemius and soleus muscles was calculated. Results Vp was significantly lower for all muscle groups in PAD patients (4.3±1.6%, 5.0±3.3% and 6.1±3.6% for anterior tibial, gastrocnemius and soleus muscles, respectively) compared to healthy control subjects (9.1±2.0%, 8.9±1.9% and 9.3±2.1%). Differences in Vp between muscle groups were not significant. The coefficient of variation of Vp varied from 10–14% and 11–16% at interscan and interreader level, respectively. Conclusions Using DCE MRI after contrast-enhanced MR angiography with gadofosveset enables reproducible assessment of hyperemic fractional microvascular blood plasma volume of the calf musculature. Vp was lower in PAD patients than in healthy controls, which reflects a promising functional (hemodynamic) biomarker for the microvascular impairment of macrovascular lesions. PMID:22662212

Versluis, Bas; Dremmen, Marjolein H. G.; Nelemans, Patty J.; Wildberger, Joachim E.; Schurink, Geert-Willem; Leiner, Tim; Backes, Walter H.

2012-01-01

411

Preparation and properties of the Ni-Al/Fe-Al intermetallics composite coating produced by plasma cladding  

NASA Astrophysics Data System (ADS)

A novel approach to produce an intermetallic composite coating was put forward. The microstructure, microhardness, and dry-sliding wear behavior of the composite coating were investigated using X-ray diffraction (XRD), scanning electron microscopy (SEM), energy dispersive spectrum (EDS) analysis, microhardness test, and ball-on-disc wear experiment. XRD results indicate that some new phases FeAl, Fe0.23Ni0.77Al, and Ni3Al exit in the composite coating with the Al2O3 addition. SEM results show that the coating is bonded with carbon steel metallurgically and exhibits typical rapid directional solidification structures. The Cr7C3 carbide and intermetallic compounds co-reinforced composite coating has a high average hardness and exhibits an excellent wear resistance under dry-sliding wear test compared with the Cr7C3 carbide-reinforced composite coating. The formation mechanism of the intermetallic compounds was also investigated.

Zhang, Li-Min; Liu, Bang-Wu; Sun, Dong-Bai

2011-12-01

412

Study of 1–8 keV K-? x-ray emission from high intensity femtosecond laser produced plasma  

SciTech Connect

We report an experimental study on the optimization of a laser plasma based x-ray source of ultra-short duration K-? line radiation. The interaction of pulses from a CPA based Ti:sapphire laser (10 TW, 45 fs, 10 Hz) system with magnesium, titanium, iron and copper solid target generates bright 1-8 keV K-? x-ray radiation. The x-ray yield was optimized with the laser pulse duration (at fixed fluence) which is varied in the range of 45 fs to 1.4 ps. It showed a maximum at laser pulse duration of ?740 fs, 420 fs, 350 and 250 fs for Mg (1.3 keV), Ti (4.5 keV), Fe (6.4 keV) and Cu (8.05 keV) respectively. The x-ray yield is observed to be independent of the sign of the chirp. The scaling of the K-? yield (I{sub x} ? I{sub L}{sup ?}) for 45 fs and optimized pulse duration were measured for laser intensities in the region of 3 × 10{sup 14} – 8 × 10{sup 17}. The x-ray yield shows a much faster scaling exponent ? = 1.5, 2.1, 2.4 and 2.6 for Mg, Ti, Fe and Cu respectively at optimized pulse duration compared to scaling exponent of 0.65, 1.3, 1.5, and 1.7 obtained for 45 fs duration laser pulses. The laser to x-ray energy conversion efficiencies obtained for different target materials are ?{sub Mg} = 1.2 × 10{sup ?5}, ?{sub Ti} = 3.1 × 10{sup ?5}, ?{sub Fe} = 2.7 × 10{sup ?5}, ?{sub Cu} = 1.9 × 10{sup ?5}. The results have been explained from the efficient generation of optimal energy hot electrons at longer laser pulse duration. The faster scaling observed at optimal pulse duration indicates that the x-ray source is generated at the target surface and saturation of x-ray emission would appear at larger laser fluence. An example of utilization of the source for measurement of shock-wave profiles in a silicon crystal by time resolved x-ray diffraction is also presented.

Arora, V., E-mail: arora@rrcat.gov.in; Naik, P. A.; Chakera, J. A.; Bagchi, S.; Tayyab, M.; Gupta, P. D. [Laser Plasma Division, Raja Rammana Centre for Advanced Technology, Indore 452 013 (India)] [Laser Plasma Division, Raja Rammana Centre for Advanced Technology, Indore 452 013 (India)

2014-04-15

413

Initial indications for the production of a strongly coupled plasma in Pb+Pb collisions at {radical}(s{sub NN})=2.76 TeV  

SciTech Connect

Results from first measurements of charged-particle differential elliptic flow, obtained in Pb+Pb collisions at {radical}(s{sub NN})=2.76 TeV with the ALICE detector at CERN's Large Hadron Collider (LHC), are compared to those obtained for Au+Au collisions at {radical}(s{sub NN})=0.2 TeV with the PHENIX detector at BNL's Relativistic Heavy Ion Collider (RHIC). The comparisons, made as a function of centrality (cent) or the number of participant pairs (N{sub part}) and particle transverse momentum p{sub T}, indicate an excellent agreement between the magnitude and trends for the flow coefficients v{sub 2}(p{sub T},cent). Analysis indicates that the averaged specific viscosity of the quark gluon plasma (QGP) produced in LHC collisions is similar to that for the strongly coupled QGP produced in RHIC collisions.

Lacey, Roy A.; Taranenko, A.; Ajitanand, N. N.; Alexander, J. M. [Department of Chemistry, Stony Brook University, Stony Brook, New York 11794-3400 (United States)

2011-03-15

414

Fabrication of nanoscale patterns in lithium fluoride crystal using a 13.5 nm Schwarzschild objective and a laser produced plasma source  

SciTech Connect

Lithium fluoride (LiF) crystal is a radiation sensitive material widely used as EUV and soft x-ray detector. The LiF-based detector has high resolution, in principle limited by the point defect size, large field of view, and wide dynamic range. Using LiF crystal as an imaging detector, a resolution of 900 nm was achieved by a projection imaging of test meshes with a Schwarzschild objective operating at 13.5 nm. In addition, by imaging of a pinhole illuminated by the plasma, an EUV spot of 1.5 {mu}m diameter in the image plane of the objective was generated, which accomplished direct writing of color centers with resolution of 800 nm. In order to avoid sample damage and contamination due to the influence of huge debris flux produced by the plasma source, a spherical normal-incidence condenser was used to collect EUV radiation. Together with a description of experimental results, the development of the Schwarzschild objective, the influence of condenser on energy density and the alignment of the imaging system are also reported.

Wang Xin [Key Laboratory of Advanced Micro-structured Materials, MOE, Department of Physics, Institute of Precision Optical Engineering, Tongji University, Shanghai 200092 (China); School of Aerospace Engineering and Applied Mechanics, Tongji University, Shanghai 200092 (China); Mu Baozhong; Jiang Li; Zhu Jingtao; Yi Shengzhen; Wang Zhanshan [Key Laboratory of Advanced Micro-structured Materials, MOE, Department of Physics, Institute of Precision Optical Engineering, Tongji University, Shanghai 200092 (China); He Pengfei [School of Aerospace Engineering and Applied Mechanics, Tongji University, Shanghai 200092 (China)

2011-12-15

415

Heights integrated model as instrument for simulation of hydrodynamic, radiation transport, and heat conduction phenomena of laser-produced plasma in EUV applications.  

SciTech Connect

The HEIGHTS integrated model has been developed as an instrument for simulation and optimization of laser-produced plasma (LPP) sources relevant to extreme ultraviolet (EUV) lithography. The model combines three general parts: hydrodynamics, radiation transport, and heat conduction. The first part employs a total variation diminishing scheme in the Lax-Friedrich formulation (TVD-LF); the second part, a Monte Carlo model; and the third part, implicit schemes with sparse matrix technology. All model parts consider physical processes in three-dimensional geometry. The influence of a generated magnetic field on laser plasma behavior was estimated, and it was found that this effect could be neglected for laser intensities relevant to EUV (up to {approx}10{sup 12} W/cm{sup 2}). All applied schemes were tested on analytical problems separately. Benchmark modeling of the full EUV source problem with a planar tin target showed good correspondence with experimental and theoretical data. Preliminary results are presented for tin droplet- and planar-target LPP devices. The influence of three-dimensional effects on EUV properties of source is discussed.

Sizyuk, V.; Hassanein, A.; Morozov, V.; Sizyuk, T.; Mathematics and Computer Science

2007-01-16

416

Initiation of rubber biosynthesis: in vitro comparisons of benzophenone-modified diphosphate analogue structure in three natural rubber-producing species  

Technology Transfer Automated Retrieval System (TEKTRAN)

Natural rubber is synthesized by initiation with one allylic pyrophosphate (APPs) molecule followed by elongation with thousands of isopentenyl pyrophosphate (IPP) molecules by the enzyme rubber transferase (a cis-prenyl transferase). To better understand how rubber transferase initiates and binds A...

417

Some preliminary evaluations of black coating on aluminium AA2219 alloy produced by plasma electrolytic oxidation (PEO) process for space applications  

NASA Astrophysics Data System (ADS)

This paper describes the results of a study of a black coating produced on aluminium AA2219 alloy using a process that involves creation of a hard ceramic oxide layer on the surface of the alloy by plasma electrolytic oxidation (PEO) known as the 'KERONITE®' process. Coating microstructure has been examined and the coating characteristics such as porosity, hardness, adhesion and phase composition were measured. The thermo-optical properties such as solar absorptance 'as' and normal infrared emittance 'en-IR' of the coating were measured in the 'as-prepared' condition and after environmental exposures to humidity, thermal cycling and UV-radiation in vacuum and to thermal shock. Comparison was made with alternative coatings produced using standard black anodising processes. The study also looked at the cold welding and friction behaviours of the coated alloy in vacuum and in an ambient laboratory environment. Standard spacecraft materials tests were conducted on the coated disc against an AISI 52100 steel ball and also against a coated pin using a pin-on-disc apparatus. Parameters such as friction coefficient and wear depth were measured and the cold welding behaviours were investigated. Test results were compared with the data generated for NiCr plated and anodised coatings. Corrosion performance was assessed using a salt spray exposure test and using an accelerated electrochemical test method. In addition, the study looked at the effect of post coating sealing with a sol-gel solution.

Shrestha, S.; Merstallinger, A.; Sickert, D.; Dunn, B. D.

2003-09-01

418

Using a dual plasma process to produce cobalt--polypyrrole catalysts for the oxygen reduction reaction in fuel cells -- part II: analysing the chemical structure of the films  

E-print Network

The chemical structure of cobalt--polypyrrole -- produced by a dual plasma process -- is analysed by means of X-ray photoelectron spectroscopy (XPS), near edge X-ray absorption spectroscopy (NEXAFS), X-ray diffraction (XRD), energy-dispersive X-Ray spectroscopy (EDX) and extended x-ray absorption spectroscopy (EXAFS).It is shown that only nanoparticles of a size of 3\\,nm with the low temperature crystal structure of cobalt are present within the compound. Besides that, cobalt--nitrogen and carbon--oxygen structures are observed. Furthermore, more and more cobalt--nitrogen structures are produced when increasing the magnetron power. Linking the information on the chemical structure to the results about the catalytic activity of the films -- which are presented in part I of this contribution -- it is concluded that the cobalt--nitrogen structures are the probable catalytically active sites. The cobalt--nitrogen bond length is calculated as 2.09\\,\\AA\\ and the carbon--nitrogen bond length as 1.38\\,\\AA.

Walter, Christian; Vyalikh, Denis; Brüser, Volker; Quade, Antje; Weltmann, Klaus-Dieter; 10.1149/2.043209jes

2012-01-01

419

Plasma medicine  

Microsoft Academic Search

Different aspects of plasma medicine, the new branch interdisciplinary between plasma chemistry and medicine, are considered.\\u000a It was shown that complex biological processes in living tissues and bodies can be controlled, stimulated, catalyzed, and\\u000a diagnosed with the use of low-temperature, atmospheric-pressure air plasma. It was found that discharge plasma can produce\\u000a the desired therapeutic effect in wound sterilization and healing,

V. N. Vasilets; A. Gutsol; A. B. Shekhter; A. Fridman

2009-01-01

420

Simulation results of an inductively-coupled rf plasma torch in two and three dimensions for producing a metal matrix composite for nuclear fuel cladding  

E-print Network

I propose to develop a new method for the synthesis of metal matrix composites (MMC) using aerosol reactants in a radio frequency (RF) plasma torch. An inductivelycoupled RF plasma torch (ICPT) may potentially be designed to maintain laminar flow...

Holik III, Eddie Frank (Trey)

2009-05-15

421

First Initial community-acquired meningitis due to extended-spectrum beta-lactamase producing Escherichia coli complicated with multiple aortic mycotic aneurysms  

PubMed Central

We report the first case of extended-spectrum beta-lactamase producing E. coli community-acquired meningitis complicated with multiple aortic mycotic aneurysms. Because of the acute aneurysm expansion with possible impending rupture on 2 abdominal CT scan, the patient underwent prompt vascular surgery and broad spectrum antibiotic therapy but he died of a hemorrhagic shock. Extended-spectrum beta-lactamase producing E. coli was identified from both blood and cerebrospinal fluid culture before vascular treatment. The present case report does not however change the guidelines of Gram negative bacteria meningitis in adults. PMID:22321435

2012-01-01

422

First initial community-acquired meningitis due to extended-spectrum beta-lactamase producing Escherichia coli complicated with multiple aortic mycotic aneurysms.  

PubMed

We report the first case of extended-spectrum beta-lactamase producing E. coli community-acquired meningitis complicated with multiple aortic mycotic aneurysms. Because of the acute aneurysm expansion with possible impending rupture on 2 abdominal CT scan, the patient underwent prompt vascular surgery and broad spectrum antibiotic therapy but he died of a hemorrhagic shock. Extended-spectrum beta-lactamase producing E. coli was identified from both blood and cerebrospinal fluid culture before vascular treatment. The present case report does not however change the guidelines of Gram negative bacteria meningitis in adults. PMID:22321435

Weyrich, Pierre; Ettahar, Nicolas; Legout, Laurence; Meybeck, Agnes; Leroy, Olivier; Senneville, Eric

2012-01-01

423

Concomitant angiotensin AT1 receptor antagonism and neprilysin inhibition produces omapatrilat-like antihypertensive effects without promoting tracheal plasma extravasation in the rat.  

PubMed

Dual inhibition of angiotensin-converting enzyme (ACE) and neprilysin (NEP) by drugs such as omapatrilat produces superior antihypertensive efficacy but cause high incidence of angioedema. We examined whether dual inhibition of angiotensin AT1 receptor (ARB) and NEP (ARB-NEPI, valsartan-candoxatril) provides similar efficacy to omapatrilat without the risk of angioedema. Activity of test compounds at the targets was assayed using fluorescence-based enzyme assays (ACE, NEP, aminopeptidase P) or competition binding assays (AT1). Target engagement in vivo (ACE, AT1, and NEP) was quantified by measuring inhibition of angiotensin-pressor responses and potentiation of atrial natriuretic peptide-induced urinary cyclic guanosine monophosphate (cGMP) output in rats. Tracheal plasma extravasation (TPE) was used as a surrogate to assess propensity of compounds to promote upper airway angioedema. Antihypertensive efficacy in renin-dependent and -independent states was measured in spontaneously hypertensive rats and deoxycorticosterone acetate salt hypertensive rats, respectively. Administration of omapatrilat and coadministration of valsartan and candoxatril blocked angiotensin induced vasopressor responses and potentiated atrial natriuretic peptide-induced increase in urinary cGMP output. In spontaneously hypertensive rats, valsartan, omapatrilat, and valsartan-candoxatril combination all produced reduction in blood pressure to a similar extent, whereas candoxatril was ineffective. In deoxycorticosterone acetate rats, omapatrilat, candoxatril, and valsartan-candoxatril combination but not valsartan produced reduction in blood pressure. Antihypertensive doses of omapatrilat produced robust increases in TPE; by contrast, valsartan, candoxatril, or their combination did not increase TPE. Pretreatment with icatibant, a bradykinin B2 antagonist, abolished omapatrilat-induced TPE but not its antihypertensive effects. On the background of NEP inhibition, suppression of the renin-angiotensin system through ARB and ACE inhibition shows a similar antihypertensive efficacy but exerts differential effects on bradykinin metabolism and TPE indicative of reduced risk of angioedema. Thus, dual AT1 receptor blockade and NEP inhibition is potentially an attractive approach to retain the excellent antihypertensive effects of omapatrilat but with a superior safety profile. PMID:21297495

Hegde, Laxminarayan G; Yu, Cecile; Renner, Travis; Thibodeaux, Harold; Armstrong, Scott R; Park, Timothy; Cheruvu, Madhavi; Olsufka, Rachael; Sandvik, Erik R; Lane, Cassie E; Budman, Joe; Hill, Craig M; Klein, Uwe; Hegde, Sharath S

2011-04-01

424

Characterization of a Target Plasma for MTF  

NASA Astrophysics Data System (ADS)

Magnetized Target Fusion (MTF) target plasmas are being characterized at the Los Alamos National Laboratory Colt facility. The goal of this project is to demonstrate plasma conditions meeting the requirements for an MTF initial target plasma. In the experiments discussed, a z-directed current is driven through a polyethylene fiber that explodes, producing a plasma which is subsequently contained in a 2 cm radius by 2 cm high cylindrical metal wall. Technical limitations prevented the use of a cryogenically frozen deuterium fiber, as originally planned. Therefore, a polyethylene fiber was used to study plasma dynamics and to look for evidence that an exploding-fiber plasma would eventually become quiescent as the plasma expands and contacts the containing metal wall; i.e., becomes wall-confined and wall-stabilized.

Wysocki, F. J.; Taccetti, J. M.; Idzorek, G.; Oona, H.; Kirkpatrick, R. C.; Lindemuth, I. R.; Sheehey, P. T.; Thio, Y. C. F.

2004-11-01

425

Magnetocaloric properties of La0.67Ca0.33MnO3 produced by reactive spark plasma sintering and by conventional ceramic route  

NASA Astrophysics Data System (ADS)

The structural properties of ferromagnetic La0.67Ca0.33MnO3 perovskite ceramics, produced by reactive spark plasma sintering (R-SPS) and conventional solid state reaction (SSR) methods, have been investigated by combined x-ray diffraction (XRD), Mn K-edge x-ray absorption near-edge structure (XANES) and magnetometry. All the samples are single phases and crystallize in the orthorhombic structure with a Pbnm space group. A slight unit cell dilatation is observed in the R-SPS sample compared to the SSR sample. The qualitative and quantitative analyses of the XANES spectra of both samples allow us to attribute this discrepancy to a manganese electronic state change in relation to the used experimental reaction conditions: the Mn3+/Mn4+ atomic ratio is found to be equal to 0.74/0.26 and 0.66/0.34, for the R-SPS and SSR samples, respectively, the former being significantly different from that expected for stoichiometric manganite. R-SPS material processing conditions affect also the microstructure of the considered manganite. The produced ceramic is dense and fine grained, with an average grain size of about 100 nm. Consequently, the measured values of the Curie temperature, TC, and of the saturation magnetization, Ms, at low temperature decrease significantly in the former compared to the latter. The maximum of the magnetic entropy change, -? SMMax, is lower in the R-SPS sample than in the SSR sample, but the thermal variation of ??SM is broader, resulting in a higher relative cooling power (RCP) in the former.

Regaieg, Y.; Ayadi, F.; Monnier, J.; Reguer, S.; Koubaa, M.; Cheikhrouhou, A.; Nowak, S.; Sicard, L.; Ammar-Merah, S.

2014-12-01

426

Optimization of initial substrate and pH levels for germination of sporing hydrogen-producing anaerobes in cow dung compost  

Microsoft Academic Search

Biohydrogen production by anaerobic microbes enriched from heat-shocked cow dung compost was studied by using an artificial medium containing sucrose. Initial pH and substrate levels were selected as target factors in this study. Our experimental results demonstrated that optimal substrate concentration and pH for the composts generating hydrogen gas were 4.0±0.5 g sucrose\\/l and 5.4±0.2, respectively. Supplementary experiments confirmed that

Yaoting Fan; Chenlin Li; Jiunn-Jyi Lay; Hongwei Hou; Gaosheng Zhang

2004-01-01

427

Ne-like ion x-ray laser experiments in plasmas produced by 0. 53-. mu. m and 0. 35-. mu. m laser light  

SciTech Connect

Recent Ne-like ion x-ray laser experiments carried out at the Centre d'Etudes de Limeil-Valenton (CEL-V) with both 0.53-..mu..m and 0.35-..mu..m laser light will be described. This paper will concentrate primarily on the observation of amplification in Ne-like Sr (Z = 38) in plasmas produced by 0.53-..mu..m laser light. Small signal gains of 4.4 cm/sup /minus/1/ and 4.0 cm/sup /minus/1/ have been measured for the Ne-like Sr J = 2--1 transitions at 164.1 and 166.5 /angstrom/, respectively. In addition, the effects of pumping the Ne-like Se laser with 0.35-..mu..m light have been investigated. The resulting Se spectra do not differ significantl